uu.seUppsala universitets publikasjoner
Endre søk
Begrens søket
12 1 - 50 of 92
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Abbrent, Sabina
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen.
    Lindgren, J
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen.
    Tegenfeldt, J
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen.
    Wendsjö, Å
    Gel electrolytes prepared from oligo(ethylene glycol)dimethacrylate: glass transition, conductivity and Li+-coordination1998Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 43, nr 10-11, s. 1185-1191s. 1185-1191Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of two plasticizers, propylene carbonate and dimethyl sulphoxide, as well as different salt concentrations of Li(TFSI), on properties of a polymer gel electrolyte material has been studied using differential scanning calorimetry (DSC) and ac impedance and FTIR spectroscopy. Variations of glass transition temperature and the conductivity behaviours of the systems were examined, and found to be highly dependent on the amount and type of the plasticizer used. Characteristic band-shifts in FTIR spectra, indicating coordination of lithium ions, have been found for the polymer and both the plasticizers in the corresponding binary solutions. These shifts were used to study the coordination preferences in the complete ternary electrolyte system. The combined results from the three experimental techniques have been discussed.

  • 2. Abyaneh, Morteza Y
    Electrocrystallization of lead dioxide: Analysis of the early stages of nucleation and growth2010Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 55, s. 3572-3579Artikkel i tidsskrift (Fagfellevurdert)
  • 3.
    Abyaneh, Morteza Y
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Historisk-filosofiska fakulteten, Filosofiska institutionen.
    Homogeneous and Heterogeneous Nucleation in ElectrocrystallizationInngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The belief amongst most electrochemists that the appropriate models, representing “homogeneous” and “heterogeneous” nucleation in the context of electrocrystallization, are spherical and spherical-cap shapes, respectively, is challenged. A proper foundation for modelling heterogeneous nucleation is introduced. The free energy required for the formation of a nucleus within an indent is derived and compared with that required for the formation of a nucleus onto a flat surface of an electrode. It is shown for the first time, using the classical theory of nucleation, that a much smaller free energy is required for nucleating within an indent on the surface of an electrode than nucleating onto a flat electrode surface. The applicability of the model, with the corresponding equations, to nucleation in the context of electrocrystallization is established. 

  • 4.
    Aitola, Kerttu
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Halme, Janne
    Feldt, Sandra
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Lohse, Peter
    Borghei, Maryam
    Kaskela, Antti
    Nasibulin, Albert G.
    Kauppinen, Esko I.
    Lund, Peter D.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Highly catalytic carbon nanotube counter electrode on plastic for dye solar cells utilizing cobalt-based redox mediator2013Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 111, s. 206-209Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A flexible, slightly transparent and metal-free random network of single-walled carbon nanotubes (SWCNTs) on plain polyethylene terephthalate (PET) plastic substrate outperformed platinum on conductive glass and on plastic as the counter electrode (CE) of a dye solar cell employing a Co(II/III)tris(2,2'-bipyridyl) complex redox mediator in 3-methoxypropionitrile solvent. The CE charge-transfer resistance of the SWCNT film was 0.60 Omega cm(2), 4.0 Omega cm(2) for sputtered platinum on indium tin oxide-PET substrate and 1.7 Omega cm(2) for thermally deposited Pt on fluorine-doped tin oxide glass, respectively. The solar cell efficiencies were in the same range, thus proving that an entirely carbon-based SWCNT film on plastic is as good CE candidate for the Co electrolyte. (C) 2013 Elsevier Ltd. All rights reserved.

  • 5. Bagheri, Narjes
    et al.
    Aghaei, Alireza
    Ghotbi, Mohammad Yeganeh
    Marzbanrad, Ehsan
    Vlachopoulos, Nick
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Haggman, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Wang, Michael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Skunik-Nuckowska, Magdalena
    Kulesza, Pawel. J.
    Combination of Asymmetric Supercapacitor Utilizing Activated Carbon and Nickel Oxide with Cobalt Polypyridyl-Based Dye-Sensitized Solar Cell2014Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 143, s. 390-397Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A dye-sensitized solar cell (DSC) based on the metal-free organic sensitizer and the cobalt (II, III) polypyridyl electrolyte was integrated here within an asymmetric supercapacitor utilizing cobalt-doped nickel oxide and activated carbon as positive and negative electrodes, respectively. A low cost nickel foil served as intermediate (auxiliary) bifunctional electrode separating two parts of the device and permitting the DSC electrolyte regeneration at one side and charge storage within cobalt-doped nickel oxide at the other. The main purpose of the research was to develop an integrated photocapacitor system capable of both energy generation and its further storage. Following irradiation at the 100 mW cm(-2) level, the solar cell generated an open-circuit voltage of 0.8 V and short-circuit current of 8 mA cm(-2) which corresponds to energy conversion efficiency of 4.9%. It was further shown that upon integration with asymmetric supercapacitor, the photogenerated energy was directly injected into porous charge storage electrodes thus resulting in specific capacitance of 32 F g(-1) and energy density of 2.3 Wh kg(-1). The coulumbic and total (energy conversion and charge storage) efficiency of photocapacitor were equal to 54% and 0.6%, respectively.

  • 6.
    Bagheri, Narjes
    et al.
    Mat & Energy Res Ctr, Div Ceram, POB 31787-316, Karaj, Iran..
    Aghaei, Alireza
    Mat & Energy Res Ctr, Div Ceram, POB 31787-316, Karaj, Iran..
    Vlachopoulos, Nick
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Skunik-Nuckowska, Magdalena
    Univ Warsaw, Fac Chem, Pasteura 1, PL-02093 Warsaw, Poland..
    Kulesza, Pawel J.
    Univ Warsaw, Fac Chem, Pasteura 1, PL-02093 Warsaw, Poland..
    Häggman, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Univ Paris 07, Sorbonne Paris Cite, CNRS, UMR 7086,ITODYS, 15 Rue Jean Antoinede Baif, F-75205 Paris 13, France.;Sungkyankwan Univ, Sch Chem Engn, Suwon 440746, South Korea..
    Physicochemical identity and charge storage properties of battery-type nickel oxide material and its composites with activated carbon2016Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 194, s. 480-488Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structural properties of annealed nickel oxide and its composites with activated carbon (synthesized via simple precipitation methods) have been addressed using X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption/desorption method and scanning electron microscopy. The charge storage properties of materials have also been investigated in three-and two-electrode configurations by means of cyclic voltammetry and galvanostatic charging/discharging in alkaline media. The results are consistent with the view that, depending on a method of preparation, the resulting nickel oxide films may exhibit redox characteristics different from that typically observed for nickel oxide-based materials. It is demonstrated that faradaic-type (redox) reactions, that are typical for battery-like materials, contribute predominantly to the high electrode capacity of 257C g(-1) (at 0.1 A g(-1)). By combining nickel oxide with a capacitive material such as activated carbon within the two-electrode symmetric cell, systems with increased charge-storage capabilities have been obtained. The fact, that the voltage window of nickel oxide-based cell has been broadened positively from 0.6 V to 1 V upon introduction of activated carbon, has also resulted in the increase of the cell's energy and power densities as well. 

  • 7.
    Bayrak Pehlivan, Ilknur
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Georén, Peter
    Marsal, Roser
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ion conduction of branched polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide electrolytes2011Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 57, s. 201-206Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ionic conductivity of polymer electrolytes containing branched poly (ethylene imine) (BPEI) and lithium bis(trifluoromethyl sulfonyl)imide (LiTFSI) was measured between temperatures of 20 and 70◦C and molar ratios of 20:1 and 400:1. The electrolytes were characterized by impedance spectroscopy, differential scanning calorimetry, and viscosity measurements. At room temperature, the maximum conductivity was 2×10−6 S/cm at a molar ratio of 50:1. The molar conductivity of the electrolytes displayed first a minimum and then a maximum upon increasing salt concentration. A proportionality of molar conductivity to segmental mobility was seen from glass transition temperature and viscosity measurements. Analysis of the Walden product and isoviscosity conductivity showed that the percentage of ions bound in ion pairs increased at low concentrations below 0.1 mol/kg. The average dipole moment decreased with salt concentration. The temperature dependence of the ionic conductivity showed an Arrhenius behavior.

  • 8.
    Bayrak Pehlivan, Ilknur
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ion conduction mechanism of nanocomposite polymer electrolytes comprised of polyethyleneimine–lithium bis(trifluoromethylsulfonyl)imide and silica2014Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 119, s. 164-168Artikkel i tidsskrift (Fagfellevurdert)
  • 9.
    Bergman, Martin
    et al.
    Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden..
    Bergfelt, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Polymerkemi.
    Sun, Bing
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Bowden, Tim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Polymerkemi.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. Uppsala Univ, Dept Chem, Angstrom Lab, SE-75121 Uppsala, Sweden..
    Johansson, Patrik
    Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden..
    Graft copolymer electrolytes for high temperature Li-battery applications, using poly(methyl methacrylate) grafted poly(ethylene glycol)methyl ether methacrylate and lithium bis(trifluoromethanesulfonimide)2015Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 175, s. 96-103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For successful hybridization of heavy vehicles, high temperature batteries might be the solution. Here, high temperature solid polymer electrolytes (SPE's) based on different ratios of poly(methyl methacrylate) (PMMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA), with LiTFSI salt (at a fixed ether oxygen (EO):Li ratio of 20:1) have been prepared and investigated. The copolymers comprise PMMA backbones with grafted PEGMA side-chains containing 9 EO units. The SPE systems were characterized using Raman spectroscopy, broadband dielectric spectroscopy, differential scanning calorimetry, thermal gravimetric analysis, and electrochemical cycling in prototype cells, with a particular focus on the 83 wt% PEGMA system. The electrolytes have good thermal stabilities and dissociate the LiTFSI salt easily, while at the same time maintaining low glass transition temperatures (T-g's). Depending on the polymeric structure, ionic conductivities >1 mS cm(-1) at 110 degrees C are detected, thus providing ion transport properties for a broad range of electrochemical applications. Prototype Li vertical bar polymer electrolyte vertical bar LiFePO4 cells utilizing the SPE at 60 degrees C showed surprisingly low capacities (<20 mA h g(-1) LiFePO4), which could be due to poor electrode/electrolyte contacts.

  • 10.
    Brandell, Daniel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Joemetsa, Silver
    Kasemaegi, Heiki
    Aabloo, Alvo
    Molecular Dynamics modelling a small-molecule crystalline electrolyte: LiBF4(CH3O(CH2CH2O)(4)CH3)(0.5)2013Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 104, s. 33-40Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Molecular Dynamics techniques have been used to investigate structure and ion conductivity in the glyme-based crystalline electrolyte LiBF4(CH3O(CH2CH2O)(4)CH3)(0.5). The structure allows ionic transport in two distinct directions in the structure, y or z, resulting in anisotropic effects. MD simulations have also been carried out under external electric fields of 1-5 x 10(6) V/m, imposed in y- or z-directions, to induce ion transport on a short time-space scale at room temperature conditions. The MD simulations reproduce the experimentally determined structure satisfactorily, and also the unusually high cationic transport numbers (t(+) > 0.6). The simulations suggest that the ion transport is dominated by the Li-ions inside the glyme complexes, while the Li-ions outside comprise stable complexes with the generally immobilized anions. 

  • 11.
    Brandell, Daniel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Kasemägi, Heiki
    Aabloo, Alvo
    Poly(ethylene oxide)-poly(butadiene) interpenetrated networks as electroactive polymers for actuators: a molecular dynamics study2010Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 55, nr 4, s. 1333-1337Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Molecular dynamics (MD)techniques have been used to study ionic transport and coordination stability in an interpenetrating polymer (IPN) network used as electrolyte for actuator devices. The system consisted of poly(ethylene oxide) (PEO) and poly(butadiene) (PB) in a 80/20% weight ratio at a total polymer of 32%, immersed into propylene carbonate (PC) solutions of LiClO4. The system has been studied for five different concentrations of LiClO4 in PC: 0.25, 0.5, 0.75, 1.0 and 1.25 M, and with applied external electric fields of 0. 1 and 5 MV/m. It is shown that the polymer matrix has little involvement in the movement of ions and solvent, but that the polymer arrangement is important for the solvent phase nano-structure, and thereby influences the mobility. The mobility of PC is higher than of the other species in the system, but the charged species display higher mobility under external field. The field threshold level for conductivity processes is between 1 and 5 MV/m. It is argued that ion pairing, phase separation and coordination stability are important for the overall dynamic properties.

  • 12.
    Brandell, Daniel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Priimaegi, Priit
    Kasemaegi, Heiki
    Aabloo, Alvo
    Branched polyethylene/poly(ethylene oxide) as a host matrix for Li-ion battery electrolytes: A molecular dynamics study2011Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 57, s. 228-236Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article discusses the structural and dynamic properties of a model polymer electrolyte system suitable for Li-ion batteries, investigated by Molecular Dynamics simulations at 293 K. It consists of a non-polar polyethylene backbone, onto which polar oligomeric polyethylene oxide side-chains of length 4-15 EO units are attached. LiPF(6) salt is dissolved into the matrix to a concentration corresponding to a Li:EO ratio of 1:12. It is found that the system display significantly higher mobility values that linear PEO using the same concentration, which is attributed to the high side-chain dynamics and the polar/non-polar topology of the system. An optimum side-chain length of 10 EO units is found for many properties, such as the dissolution of salt, although the Li(+) ion diffusion was found to be the highest for side-chain lengths of 15 EO units: 1.54 x 10(-13) m(2) s(-1).

  • 13.
    Bryngelsson, Hanna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Eskhult, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Electrodeposition and electrochemical characterisation of thick and thin coatings of Sb and Sb/Sb2O3 particles for Li-ion battery anodes2007Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 53, nr 3, s. 1062-1073Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The possibilities to electrodeposit thick coatings composed of nanoparticles of Sb and Sb2O3 for use as high-capacity anode materials in Li-ion batteries have been investigated. It is demonstrated that the stability of the coatings depends on their Sb2O3 concentrations as well as microstructure. The electrodeposition reactions in electrolytes with different pH and buffer capacities were studied using chronopotentiometry and electrochemical quartz crystal microbalance measurements. The obtained deposits, which were characterised with XRD and SEM, were also tested as anode materials in Li-ion batteries. The influence of the pH and buffer capacity of the deposition solution on the composition and particle size of the deposits were studied and it is concluded that depositions from a poorly buffered solution of antimony-tartrate give rise to good anode materials due to the inclusion of precipitated Sb2O3 nanoparticles in the Sb coatings. Depositions under conditions yielding pure Sb coatings give rise to deposits composed of large crystalline particles with poor anode stabilities. The presence of a plateau at about 0.8V versus Li+/Li due to SEI forming reactions and the origin of another plateau at about 0.4 V versus Li+/Li seen during the lithiation of thin Sb coatings are also discussed. It is demonstrated that the 0.4 V plateau is present for Sb coatings for which the (0 1 2) peak is the main peak in the XRD diffractogram.

  • 14.
    Bryngelsson, Hanna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Eskhult, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Thin films of Cu2Sb and Cu9Sb2 as anode materials in Li-ion batteries2008Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 53, nr 24, s. 7226-7234Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thin Cu2Sb films have been prepared by heat-treating Sb films. electrodeposited on Cu substrates. The influence of the electrodeposition conditions and the heat-treatment period on composition and morphology of the films were investigated (SEM and XRD) and the obtained films were tested as anode materials for Li-ion batteries. The Cu2Sb material showed a stable capacity of 290 mAh g(-1) (close to the theoretical capacity of 323 mAh g-1) during more than 60 cycles. The presence of 9-11% (w/w) Sb2O3 in the electrodeposited films resulted in smaller particles but also slowed down formation of Cu2Sb during the heat-treatment step. The presence of Sb2O3 was found to decrease the cycling stability although structural reversibility of Cu2Sb was obtained both with and without Sb2O3. Longer heat-treatment of pure Sb films resulted in the formation of Cu9Sb2 which was shown to be reduced at a lower potential than Cu2Sb. The Cu9Sb2 was converted to Cu2Sb during repeated cycling and the capacity of the latter Cu2Sb material was found to be 230 mAh g(-1). While reduction of the materials was complicated by simultaneous formation of an SEI layer, three plateaus Could be identified during the oxidation of Li3Sb, indicating the presence of three separate one-electron oxidation reactions.

  • 15.
    Bucur, R. V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    State of the pre-adsorbed sulfur on a rough platinum electrode in voltammetric conditions: Microgravimetric measurements with electrochemical quartz crystal microbalance2013Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 87, s. 186-193Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The removal of the chemisorbed sulfur from the surface of the rough Pt electrode was investigated by combined coulometric and gravimetric measurements using the cyclic voltammetry (CV) and the electrochemical quartz crystal microbalance (EQCMB) methods. Pt surface was covered with elemental sulfur in 1 M solutions of Na2S and tiourea (TU) at open circuit potential, for a period between 60 s and 300 s. CV was performed in 0.1 M HClO4, 0.1 M NaOH and 1 M NaOH solutions, while EQCM in 1 M NaOH solution, in the air, at 296 K. The balance of the oxidation reaction was calculated with the anodic and cathodic charges involved in CV and the mass variation of the rough Pt electrode through the frequency shift of the piezoelectric sensor. Discrepancies in the mass balance calculated by coulometry and microgravimetry were ascribed to the complexity of the removal mechanism. By each cycle, S is removed from the surface as SO3 in two stages: a fraction in the anodic scan, simultaneous with the oxidation process (faradaic process) and a remaining fraction in the cathodic scan, by electro-desorption (non-faradaic process). The whole process is biased by the potential of the electrode (the electrical field at the interface). The balance can be thoroughly equilibrated by invoking a "hidden" process embedded in the cathodic scan, accountable for the non-faradaic removal of additional mass of sulfur. This process could be caused by the adsorbate-adsorbate (S*/SO3* or S*/O*) interaction and is not detectable in CV measurements. Consequently, the S coverage calculated in CV by anodic and cathodic charge balance yields lower values than the real chemisorbed amount (the symbol * represents the adsorbed state of the element).

  • 16.
    Bucur, R. V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Structure of the Voltammograms of the Platinum-Black Electrodes: Derivative Voltammetry and Data Fitting Analysis2014Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 129, s. 76-84Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Voltammograms of Pt-black electrodes were recorded in aerated 1 M HClO4 solution, at T = 298 K, for three different upper values of the oxidation potential, E-max = 1.6 V, 1.44 V and 1.39 V. Numerical differentiation of the raw data enhanced details which hardly were visible in the original voltammograms. The derivative of the anodic current resided in well defined peaks attributed to two peaks-like electrode reactions (potential range 0.6 V-1.0 V) and a smooth reaction generating the anodic current plateau, at potential higher than IV. The derivative of the cathodic peaks revealed that the cathodic current results from two reactions occurring simultaneously, but with different rates: the reduction of the adsorbed - OH* followed by that of the adsorbed-O*. The data fitting analysis was performed with the empirical kinetic equations based upon the sigmoid-like functions. The analysis confirmed the results found on the derivative voltammograms and enabled to compute the individual component of the anodic and cathodic branches. Complementary mass measurements with the electrochemical quartz crystal microbalance (EQCM) confirmed that both the oxidation and the reduction processes on the Pt-black electrodes consist of a complex succession of overlapping reactions associated with both the adsorbed - OH* and - O* species. (c) 2014 Elsevier Ltd. All rights reserved.

  • 17.
    Bucur, Romulus V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    The resting-state of the Pt-black electrode in acid solution and the structure of the adsorption layer: Coulometric and electrochemical quartz crystal microbalance measurements2012Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 62, s. 354-361Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The properties of Pt-electrodes in 1 M HClO4 solution, in air, were studied both in the resting-state and mild oxidation conditions, within the potential range of 1000 mV and 1600 mV. Cyclic voltammetry (CV) and cathodic stripping voltammetry (CSV) were used for coulometric determination of the amount of O-containing species adsorbed on the electrode surface during the oxidation-reduction reactions. Simultaneously, the mass of the adsorption layer was measured in situ, with the electrochemical quartz crystal microbalance (EQCM). The surface of the Pt-black electrode in the resting-state is covered with OH*-species (apparently a ML), which are spontaneously generated by immersion in the aqueous solution without any polarization potential. The surface of the Pt smooth electrode is covered uppermost by a sub-monolayer of oxygen, in similar conditions. The resting-state of the Pt-black electrode is characterized by a reproducible value of the rest potential, E-r = 1040 +/- 5 mV (average of 10 samples) and a reduction peak in CV mode at E'(p) = 791 +/- 7 mV (average of 10 samples). In anodic polarization conditions, PtOH* is oxidized to PtO*, in CV mode, and to Pt(O-2)*, in the potentiostatic mode. The reduction peak of PtO* in CV mode is E ''(p) = 694 +/- 9 mV (average of 10 samples), indicating a stronger bond to the surface of the electrode. The yielding of Pt(O-2)* is not fast enough to accommodate the increase of the oxidation potential by finite sweep rate of the CV mode at 10 mVs(-1). Therefore this oxidation level could not be achieved in CV mode. The prolonged oxidation in the potentiostatic mode results in the coverage of the surface of Pt-black electrode with a monolayer of (O-2)*-species.

  • 18.
    Böhme, Solveig
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    On the electrochemistry of tin oxide coated tin electrodes in lithium-ion batteries2015Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 179, s. 482-494Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As tin based electrodes are of significant interest in the development of improved lithium-ion batteries it is important to understand the associated electrochemical reactions. In this work it is shown that the electrochemical behavior of SnO2 coated tin electrodes can be described based on the SnO2 and SnO conversion reactions, the lithium tin alloy formation and the oxidation of tin generating SnF2. The CV, XPS and SEM data, obtained for electrodeposited tin crystals on gold substrates, demonstrates that the capacity loss often observed for SnO2 is caused by the reformed SnO2 layer serving as a passivating layer protecting the remaining tin. Capacities corresponding up to about 80 % of the initial SnO2 capacity could, however, be obtained by cycling to 3.5 V vs. Li+/Li. It is also shown that the oxidation of the lithium tin alloy is hindered by the rate of the diffusion of lithium through a layer of tin with increasing thickness and that the irreversible oxidation of tin to SnF2 at potentials larger than 2.8 V vs. Li+/Li is due to the fact that SnF2 is formed below the SnO2 layer. This improved electrochemical understanding of the SnO2/Sn system should be valuable in the development of tin based electrodes for lithium-ion batteries.

  • 19.
    Ciosek Högström, Katarzyna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Malmgren, Sara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Hahlin, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Gorgoi, Mihaela
    Helmholtz Zentrum Berlin Germany.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Rensmo, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    The Buried Carbon/Solid Electrolyte Interphase in Li-ion Batteries Studied by Hard X-ray Photoelectron Spectroscopy2014Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 138, s. 430-436Artikkel i tidsskrift (Fagfellevurdert)
  • 20. Dahbi, Mohammed
    et al.
    Wikberg, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Saadoune, Ismael
    LCME, University Cadi Ayyad, Marrakech, Morocco.
    Gustafsson, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Svedlindh, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    A delithiated LiNi0.65Co0.25Mn0.10O2 electrode material: A structural, magnetic and electrochemical study2009Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 54, nr 11, s. 3211-3217Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A crystalline LiNi0.65Co0.25Mn0.10O2 electrode material was synthesized by the combustion method at 900 °C for 1 h. Rietveld refinement shows less than 3% of Li/Ni disorder in the structure. Lithium extraction involves only the Ni2+/Ni4+ redox couple while Co3+ and Mn4+ remain electrochemically inactive. No structural transition was detected during cycling in the whole composition range 0 < x < 1.0. Furthermore, the hexagonal cell volume changes by only 3% when all lithium was removed indicating a good mechanical stability of the studied compound. LiNi0.65Co0.25Mn0.10O2 has a discharge capacity of 150 mAh/g in the voltage range 2.5–4.5 V, but the best electrochemical performance was obtained with an upper cut-off potential of 4.3 V. Magnetic measurements reveal competing antiferromagnetic and ferromagnetic interactions – varying in strength as a function of lithium content – yielding a low temperature magnetically frustrated state. The evolution of the magnetic properties with lithium content confirms the preferential oxidation of Ni ions compared to Co3+ and Mn4+ during the delithiation process.

  • 21.
    Deak, Peter
    et al.
    Univ Bremen, Bremen Ctr Computat Mat Sci, POB 330440, D-28334 Bremen, Germany..
    Kullgren, Jolla
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Aradi, Balint
    Univ Bremen, Bremen Ctr Computat Mat Sci, POB 330440, D-28334 Bremen, Germany..
    Frauenheim, Thomas
    Univ Bremen, Bremen Ctr Computat Mat Sci, POB 330440, D-28334 Bremen, Germany..
    Kavan, Ladislaw
    Acad Sci Czech Republic, J Heyrovsky Inst Phys Chem, Dolejkova 3, CZ-18223 Prague 8, Czech Republic..
    Water splitting and the band edge positions of TiO22016Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 199, s. 27-34Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The possibility of splitting water by UV-light on a TiO2 electrode has created great interest in the material, however, it has been later questioned whether rutile can do the job at all without external bias. Anatase was suggested instead, but its efficiency is still a subject of debate. The problem is related to the position of the band edges, that is, of the Fermi-level (E-F), with respect to the redox potentials of water. Here we present hybrid-functional calculations to align the band structures with the vacuum level, assuming the rutile (110) and anatase (101) surface being exposed to water. Our results show that both are capable of water splitting if no adsorbates other than molecular water are present. On a fully hydroxylated surface (i.e., H+ and OH adsorption on undercoordinated surface oxygen and titanium atoms, respectively), E-F is only similar to 0.5 eV above the H+/H-2 potential in case of anatase, and - depending on the level of reduction roughly at, or below it for rutile. We also show, that the band edges (and E-F) shift up if OH+ groups dominate the surface, increasing the driving force for water splitting. This is in line with the experience on titania reduced in hydrogen. Our results are further confirmed by calculating E-F without the presence of water, and comparing it to work function measurements by photoelectron spectroscopy.

  • 22.
    Delices, Annette
    et al.
    Univ Paris Diderot Paris, Sorbonne Paris Cite, ITODYS UMR CNRS 7086, 15 Rue Jean Antoine de Baif, F-75205 Paris 13, France..
    Zhang, Jinbao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Santoni, Marie-Pierre
    Univ Paris Diderot Paris, Sorbonne Paris Cite, ITODYS UMR CNRS 7086, 15 Rue Jean Antoine de Baif, F-75205 Paris 13, France..
    Dong, Chang-Zhi
    Univ Paris Diderot Paris, Sorbonne Paris Cite, ITODYS UMR CNRS 7086, 15 Rue Jean Antoine de Baif, F-75205 Paris 13, France..
    Maurel, Francois
    Univ Paris Diderot Paris, Sorbonne Paris Cite, ITODYS UMR CNRS 7086, 15 Rue Jean Antoine de Baif, F-75205 Paris 13, France..
    Vlachopoulos, Nick
    Ecole Polytech Fed Lausanne, EPFL FSB ISIC LSPM, Inst Chem Sci & Engn, Lab Photomol Sci, Chemin Alambics,Stn 6, CH-1015 Lausanne, Switzerland..
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, EPFL FSB ISIC LSPM, Inst Chem Sci & Engn, Lab Photomol Sci, Chemin Alambics,Stn 6, CH-1015 Lausanne, Switzerland..
    Jouini, Mohamed
    Univ Paris Diderot Paris, Sorbonne Paris Cite, ITODYS UMR CNRS 7086, 15 Rue Jean Antoine de Baif, F-75205 Paris 13, France..
    New covalently bonded dye/hole transporting material for better charge transfer in solid-state dye-sensitized solar cells2018Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 269, s. 163-171Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel metal-free organic dye based on triarylamine functionalized by a carbazole unit is synthesized and used in solid state dye sensitized solar cells (sDSC). The carbazole is co-polymerized with bis-EDOT by in-situ photo-electrochemical polymerization leading to a hole transporting polymer material covalently bonded to the light active centre. These first photovoltaic performances results are promising in sDSCs applications.

  • 23.
    Diklic, Natasa P.
    et al.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia.
    Dobrota, Ana S.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia.
    Pasti, Igor A.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia;Royal Inst Technol, Sch Ind Engn & Management, Dept Mat Sci & Engn, KTH, Brinellvagen 23, S-10044 Stockholm, Sweden.
    Mentus, Slavko, V
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia;Serbian Acad Arts & Sci, Knez Mihajlova 35, Belgrade 11000, Serbia.
    Johansson, Börje
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi. Royal Inst Technol, Sch Ind Engn & Management, Dept Mat Sci & Engn, KTH, Brinellvagen 23, S-10044 Stockholm, Sweden.
    Skorodumova, Natalia V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Royal Inst Technol, Sch Ind Engn & Management, Dept Mat Sci & Engn, KTH, Brinellvagen 23, S-10044 Stockholm, Sweden.
    Sodium storage via single epoxy group on graphene: The role of surface doping2019Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 297, s. 523-528Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Due to its unique physical and chemical properties, graphene is being considered as a promising material for energy conversion and storage applications. Introduction of functional groups and dopants on/in graphene is a useful strategy for tuning its properties. In order to fully exploit its potential, atomic-level understanding of its interaction with species of importance for such applications is required. We present a DFT study of the interaction of sodium atoms with epoxy-graphene and analyze how this interaction is affected upon doping with boron and nitrogen. We demonstrate how the dopants, combined with oxygen-containing groups alter the reactivity of graphene towards Na. Dopants act as attractors of epoxy groups, enhancing the sodium adsorption on doped oxygen-functionalized graphene when compared to the case of non-doped epoxy-graphene. Furthermore, by considering thermodynamics of the Na interaction with doped epoxy-graphene it has been concluded that such materials are good candidates for Na storage applications. Therefore, we suggest that controlled oxidation of doped carbon materials could lead to the development of advanced anode materials for rechargeable Na-ion batteries.

  • 24.
    Dobrota, Ana S.
    et al.
    Univ Belgrade, Fac Phys Chem, Belgrade 11158, Serbia..
    Pasti, Igor A.
    Univ Belgrade, Fac Phys Chem, Belgrade 11158, Serbia..
    Mentus, Slavko V.
    Univ Belgrade, Fac Phys Chem, Belgrade 11158, Serbia.;Serbian Acad Arts & Sci, Knez Mihajlova 35, Belgrade 11000, Serbia..
    Johansson, Börje
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Skorodumova, Natalia V.
    Uppsala Univ, Dept Phys & Astron, Box 516, S-75120 Uppsala, Sweden.;KTH Royal Inst Technol, Sch Ind Engn & Management, Dept Mat Sci & Engn, Brinellvagen 23, S-10044 Stockholm, Sweden..
    Functionalized graphene for sodium battery applications: the DFT insights2017Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 250, s. 185-195Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Considering the increasing interest in the use of graphene-based materials for energy conversion and storage applications, we have performed a DFT study of Na interaction with doped graphene, both in non-oxidized and oxidized forms. Oxidation seems to play the crucial role when it comes to the interaction of doped graphene materials with sodium. The dopants act as attractors of OH groups, making the material prone to oxidation, and therefore altering its affinity towards Na. In some cases, this can result in hydroxide or water formation - an irreversible change lethal for battery performance. Our results suggest that one should carefully control the oxidation level of doped graphene-based materials if they are to be used as sodium battery electrode materials as the optimal oxidation level depends on the dopant type.

  • 25.
    Dobrota, Ana S.
    et al.
    Univ Belgrade, Fac Phys Chem, Belgrade 11158, Serbia..
    Pasti, Igor A.
    Univ Belgrade, Fac Phys Chem, Belgrade 11158, Serbia..
    Skorodumova, Natalia V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. KTH Royal Inst Technol, Sch Ind Engn & Management, Dept Mat Sci & Engn, Multiscale Mat Modelling Grp, S-10044 Stockholm, Sweden.;Uppsala Univ, Dept Phys & Astron, S-75120 Uppsala, Sweden..
    Oxidized graphene as an electrode material for rechargeable metal-ion batteries - a DFT point of view2015Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 176, s. 1092-1099Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In line with a growing interest in the use of graphene-based materials for energy storage applications and active research in the field of rechargeable metal-ion batteries we have performed a DFT based computational study of alkali metal atoms (Li, Na and K) interaction with an oxidized graphene. The presence of oxygen surface groups (epoxy and hydroxyl) alters the chemisorption properties of graphene. In particular, we observe that the epoxy groups are redox active and enhance the alkali metal adsorption energies by a factor of 2 or more. When an alkali metal atom interacts with hydroxyl-graphene the formation of metal-hydroxide is observed. In addition to a potential boost of metal ion storage capability, oxygen functional groups also prevent the precipitation of the metal phase. By simulating lithiation/de-lithiation process on epoxy-graphenes, it was concluded that the oxidized graphene can undergo structural changes during battery operation. Our results suggest that the content and the type of oxygen surface groups should be carefully tailored to maximize the performance of metal-ion batteries. This is mainly related to the control of the oxidation level in order to provide enough active centers for metal ion storage while preserving sufficient electrical conductivity.

  • 26.
    Ebadi, Mahsa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Costa, Luciano T.
    Univ Fed Fluminense, Dept Fis Quim, Inst Quim, Outeiro Sao Joao Batista S-N, BR-24020150 Niteroi, RJ, Brazil..
    Araujo, C. Moyses
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Modelling the Polymer Electrolyte/Li-Metal Interface by Molecular Dynamics simulations2017Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 234, s. 43-51Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Solid polymer electrolytes are considered promising candidates for application in Li-metal batteries due to their comparatively high mechanical strength, which can prevent dendrite formation. In this study, we have performed Molecular Dynamics simulations to investigate structural and dynamical properties of a common polymer electrolyte, poly(ethylene oxide) (PEO) doped with LiTFSI salt in the presence of a Li metal surface. Both a physical (solid wall) and a chemical (slab) model of the Li (100) surface have been applied, and the results are also compared with a model of the bulk electrolyte. The average coordination numbers for oxygen atoms around the Li ions are ca. 6 for all investigated systems. However, the calculated Radial Distribution Functions (RDFs) for Li+-(OPEO) and Li+-(OTFSI) show sharper peaks for the Li slab model, indicating a more well-defined coordination sphere for Li+ in this system. This is clearly a surface effect, since the RDF for Li+ in the interface region exhibits sharper peaks than in the bulk region of the same system. The simulations also display a high accumulation of TFSI anions and Li+ cations close to interface regions. This also leads to slower dynamics of the ionic transport in the systems, which have a Li-metal surface present, as seen from the calculated mean-square-displacement functions. The accumulation of ions close to the surface is thus likely to induce a polarization close to the electrode.

  • 27. Ek, Gustav
    et al.
    Jeschull, Fabian
    Bowden, Tim
    Brandell, Daniel
    Li-ion batteries using electrolytes based on mixtures of poly(vinyl alcohol) and lithium bis(triflouromethane) sulfonamide salt2017Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 246, s. 208-212Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Poly(vinyl alcohol) (PVA) has, to a limited degree, previously been investigated as an alternative host material to the dominating poly(ethylene oxide)-(PEO)-based polymer electrolytes used in electrochemical applications. These PVA-materials were found to be highly ionically conducting for a number of different salts at temperatures below the glass transition temperature, but in the presence of DMSO (dimethyl sulfoxide) residues. Here, we investigate the PVA:LiTFSI (lithium bis(triflouromethane) sulfonamide) electrolytes system, thereby for the first time using the salt most commonly explored in PEO-based systems also in PVA. It is shown that this results in significantly higher conductivities than for alternative Li salts. Comparisons between electrolytes casted in DMSO, H2O and hot-pressed samples confirm the necessity of solvent residues present in the DMSO casted films for the ionic transport, although no obvious liquid phase is formed. Moreover, we also show the feasibility of PVA-based electrolytes by construction of functional Li-metal broken vertical bar PVA-LiTFSI (DMSO) broken vertical bar LiFePO4 batteries operating at 60 degrees C, displaying stable capacities of 136 mAh/g LiFePO4 at a rate of C/20. (C) 2017 Elsevier Ltd. All rights reserved.

  • 28.
    Ellis, Hanna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Vlachopoulos, Nick
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Häggman, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Perruchot, Christian
    Jouini, Mohamed
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    PEDOT counter electrodes for dye-sensitized solar cells prepared by aqueous micellar electrodeposition2013Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 107, s. 45-51Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electropolymerization of 3,4-ethylenedioxythiophene (EDOT) was performed in an aqueous micellar solution onto conducting glass and conducting flexible plastic substrates using a simple, scalable process. The background electrolyte in the process consisted merely of a micellar aqueous sodium dodecyl sulfate (SDS) solution. Electrodeposition of poly(3,4-ethylenedioxythiophene) (PEDOT) was conducted at constant current, resulting in homogeneous films, even on large sized conducting glass and plastic substrates (9 cm x 9 cm). The use of water as electrolyte, application on large substrates and applicability on flexible plastic substrates demonstrates the feasibility of this method for upscaling and use in industrial fabrication of DSCs. DSCs were assembled using three different PEDOT thicknesses on conducting glass as counter electrodes and a comparison was made with thermally platinized conducting glass counter electrodes. In cobalt tris(bipyridine)-based electrolyte, the catalytic performance of the PEDOT counter electrodes was significantly higher than that of platinized counter electrodes. DSCs with PEDOT counter electrodes gave higher efficiencies due to higher fill factors and a lower charge transfer resistance. The low charge transfer resistance and good catalytic performance of the PEDOT counter electrodes can be related to its mesoporous morphology resembling crumpled sheets of paper. 

  • 29.
    Ergeneman, O.
    et al.
    ETH, Inst Robot & Intelligent Syst IRIS, CH-8092 Zurich, Switzerland..
    Sivaraman, K. M.
    ETH, Inst Robot & Intelligent Syst IRIS, CH-8092 Zurich, Switzerland..
    Pane, S.
    ETH, Inst Robot & Intelligent Syst IRIS, CH-8092 Zurich, Switzerland..
    Pellicer, E.
    Univ Autonoma Barcelona, Dept Fis, Fac Ciencies, E-08193 Barcelona, Spain..
    Teleki, A.
    ETH, Particle Technol Lab, CH-8092 Zurich, Switzerland..
    Hirt, A. M.
    ETH, Inst Geophys, CH-8092 Zurich, Switzerland..
    Baro, M. D.
    Univ Autonoma Barcelona, Dept Fis, Fac Ciencies, E-08193 Barcelona, Spain..
    Nelson, B. J.
    ETH, Inst Robot & Intelligent Syst IRIS, CH-8092 Zurich, Switzerland..
    Morphology, structure and magnetic properties of cobalt-nickel films obtained from acidic electrolytes containing glycine2011Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 56, nr 3, s. 1399-1408Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper focuses on the development and optimization of electroplated cobalt-nickel (CoNi) alloys for use in biomedical microdevices. CoNi films were electrodeposited from glycine-containing electrolyte solutions at acidic pH. The influence of pH (2.5-5), temperature (55 and 80 degrees C). current density (from -5 to -40 mA cm(-2)), glycine concentration (0.5 and 1 mol dm(-3)) and the nature of the metal salts (chlorides or sulphates) on the composition and the magnetic properties of the films were systematically analyzed. The cobalt content varied between 50 and 83 wt% depending on the applied conditions. As a result, deposits showed variable morphologies, different structures (either hexagonal close-packed (hcp) or mixed hcp and face-centered cubic phases) and tunable magnetic properties, ranging from semi-hard (18.51 kA m(-1). i.e. 233 Oe) to very soft (1.43 kA m(-1), i.e. 18 Oe). To understand the role of glycine in this system, a comparison of the electrochemical processes, and the structural and magnetic properties is made for samples produced in glycine-containing and glycine-free baths. (C) 2010 Elsevier Ltd. All rights reserved.

  • 30.
    Eriksson, Therese
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Mindemark, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Yue, Ma
    Northwestern Polytech Univ, Ctr Nano Energy Mat, Sch Mat Sci & Engn, Youyi West Rd 127, Xian, Shaanxi, Peoples R China.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Effects of nanoparticle addition to poly(epsilon-caprolactone) electrolytes: Crystallinity, conductivity and ambient temperature battery cycling2019Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 300, s. 489-496Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It has previously been shown that nanoparticle additives can, in a simple way, significantly improve the ionic conductivity in solid polymer electrolyte systems with the semi-crystalline poly(ethylene oxide) (PEO) as a host material. It has been suggested that the improved ionic conductivity is a result of reduced degree of crystallinity and additional conductivity mechanisms occurring in the material. In this work, this principle is applied to another semi-crystalline polymer host: poly(epsilon-caprolactone) (PCL). This is a polymer with comparable properties (T-g, T-m, etc.) as PEO, and constitute a promising material for use in solid polymer electrolytes for lithium ion batteries. 15 wt% of the respective nanoparticles TiO2, Al2O3 and h-BN have been added to the PCL-LiTFSI solid polymer electrolyte in an attempt to increase the conductivity and achieve stable room temperature cyclability. The crystallinity, ionic conductivity and electrochemical properties were investigated by differential scanning calorimetry, electrochemical impedance spectroscopy and galvanostatic cycling of cells. The results showed that with an addition of 15 wt% Al2O3, the degree of crystallinity is reduced to 6-7% and the ionic conductivity increased to 6-7 x 10(-6) S cm(-1) at room temperature, allowing successful cycling of cells at 30 degrees C, while h-BN did not contribute to similar improvements. The effect of nanoparticles, however, differ significantly from previous observations in PEO systems, which could be explained by different surface-polymer interactions or the degree of ordering in the amorphous phases of the materials.

  • 31.
    Eskhult, Jonas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Ulrich, Christian
    Björefors, Fredrik
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Current oscillations during chronoamperometric and cyclic voltammetric measurements in alkaline Cu(II)-citrate solutions2008Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 53, nr 5, s. 2188-2197Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is demonstrated that current oscillations can be observed during chronoamperometric and cyclic voltammetric experiments in solutions containing 0.4 M CuSO4 and 1.2 M citrate at pH 11 and 50 degrees C. The oscillations, which are shown to originate from local variations in the pH, result in the deposition of nanostructured Cu and Cu2O materials. It is concluded that the current oscillations are analogous to the previously described potential oscillations obtained under controlled current conditions in alkaline Cu(II)-lactate, -tartrate and -citrate solutions. Rotating disk electrode results clearly show that the reduction of the Cu(II)-complexes is kinetically controlled and that the rate of the reduction increases with increasing pH and temperature. It is also shown that the presence of a cathodic peak on the anodic scan in the cyclic voltammograms can be used to identify the experimental conditions leading to the spontaneous current (or potential) oscillations. Electrochemical quartz crystal microbalance results indicate that the cathodic peak stems from an increased rate of the reduction of the Cu(II)-citrate complexes due to a rapid increase in the local pH. This causes Cu2O rather than Cu to be deposited which, however, results in a decrease in the local pH and a decreasing current. In situ ellipsometry data confirm that Cu2O deposition replaces that of Cu in the potential region of the cathodic peak. The present findings should facilitate syntheses of nanolayered materials based on spontaneous potential or current oscillations.

  • 32.
    Etman, Ahmed
    et al.
    Stockholm University.
    Inge, Ken
    Stockholm University.
    Jiaru, Xu
    Peking University.
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Sun, Junliang
    Stockholm University, Peking University.
    A Water Based Synthesis of Ultrathin Hydrated Vanadium Pentoxide Nanosheets for Lithium Battery Application: Free Standing Electrodes or Conventionally Casted Electrodes?2017Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 252, s. 254-260Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Abstract: Ultrathin hydrated vanadium pentoxide (V2O5·nH2O) nanosheets are fabricated via a water based exfoliation technique. The exfoliation process involves reflux of the precursor, 1:4 mixture of VO2 and V2O5, in water at 80 °C for 24 h. Operando and ex situ X-ray diffraction (XRD) studies are conducted to follow the structural changes during the exfoliation process. The chemical and thermal analyses suggest that the molecular formula of the nanosheet is H 0.2 V 1.8 V V 0.2 IV O 5 ⋅ 0.5 H 2 O . The V2O5·nH2O nanosheets are mixed with 10% of multi-walled carbon nanotube (MW-CNT) to form a composite material assigned as (VOx-CNT). Free standing electrodes (FSE) and conventionally casted electrodes (CCE) of VOx-CNT are fabricated and then tested as a positive electrode material for lithium batteries. The FSE shows reversible capacities of 300 and 97 mAhg-1 at current densities of 10 and 200 mAhg-1, respectively. This is better than earlier reports for free-standing electrodes. The CCE delivers discharge capacities of 175 and 93 mAhg-1 at current densities of 10 and 200 mAhg-1, respectively.

  • 33.
    Farhat, Douaa
    et al.
    Univ Francois Rabelais Tours, UFR Sci & Tech, Lab PCM2E, EA 6296, Parc Grandmont, F-37200 Tours, France.
    Maibach, Julia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Eriksson, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Lemordant, Daniel
    Univ Francois Rabelais Tours, UFR Sci & Tech, Lab PCM2E, EA 6296, Parc Grandmont, F-37200 Tours, France.
    Ghamouss, Fouad
    Univ Francois Rabelais Tours, UFR Sci & Tech, Lab PCM2E, EA 6296, Parc Grandmont, F-37200 Tours, France.
    Towards high-voltage Li-ion batteries: Reversible cycling of graphite anodes and Li-ion batteries in adiponitrile-based electrolytes2018Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 281, s. 299-311Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Due to their low vapor pressure and their promising electrochemical and thermal stability, N C- (CH2)n-C N dinitriles are proposed as an electrolyte solvent for Li-ion batteries. Adiponitrile (ADN) has substantial advantages, especially for applications requiring high potential cathodes, because it has high electrochemical/thermal stability (up to 6 V vs. Li/Li+, > 120 degrees C). However, to obtain very high voltage batteries, ADN electrolytes must also passivate the anode of the battery. In this work, reversible cycling of graphite in adiponitrile was successfully achieved by adding a few percent of fluoroethylene carbonate allowing the realization of Graphite/NMC Li-ion battery. The battery of specific capacity of 135 mAhh.g(-1) showed a cycling stability for more than 40 cycles. The composition of the solid electrolyte interphase (SEI) was determined as a function of the FEC concentration as well as the state of charge of the graphite anode using hard X-ray photoelectron spectroscopy (HAXPES) and XPS. With FEC, the SEI layer is thinner and depends on the SOC of the anode, but does not depend on the FEC concentration. SEM characterizations clearly showed that the surface of the anode is completely covered by the SEI layer, regardless of the concentration of FEC. Indeed, 2% of FEC is sufficient to suppress the reduction of adiponitrile which is explained by a specific adsorption of FEC on the graphite anode.

  • 34.
    Fredriksson, Wendy
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    XPS study of duplex stainless steel as a possible current collector in a Li-ion battery2012Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 79, s. 82-94Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The surface chemistry and corrosion property of a duplex LDX 2101 steel that had been cycled in a Li-ion battery with a 1 M LiPF6 in EC/DMC 1:1 electrolyte was studied. The results are compared to those of steel stored for the same length of time. Cyclic voltammetry was used to sweep the steel between 0 V and 5 V and the different reduction products were identified with SEM, XRD and XPS. A conversion reaction occurred during the cathodic sweep between 2.0 and 1.5 V where chromium and iron oxides were reduced forming Li2O and metal. At 0.5 V vs. Li+/Li a Solid Electrolyte Interface (SEI) was irreversibly formed predominantly during the first cycle. During the oxidation sweep the typical stainless steel passive layer of chromium and iron oxides/hydroxides formed at 2.5 V vs. Li/Li+. Li2O also decomposed at this potential. Simultaneously metal fluorides are formed. The XPS revealed a thicker SEI containing organic and inorganic species on the cycled electrode than on the stored. The stored sample showed chemical formation of CrF3 on the surface. Depth profiling of the cycled electrode by Ar+ etching showed a thick layer of CrF3 and a thin layer of FeF3. We conclude that the level of corrosion of this duplex steel is acceptable in the 3–4.5 V vs. Li+/Li region. However, in a Li-ion battery it is too reactive at low potentials to be considered as a replacement for copper as an anode current collector. We also observe that the PF6 anion from the electrolyte salt plays an important role in the formation of metal fluorides which is a fact generally neglected in the discussion of conversion reactions of metal-oxide anodes for Li-ion batteries. For stainless steel to be considered as current collectors for Li-ion batteries optimisation of alloy compositions need to be made to reduce corrosion occurring during cycling in organic solvents.

  • 35.
    Frenning, Göran
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap.
    Nilsson, M
    Westlinder, Jörgen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap.
    Strømme Mattsson, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap.
    Dielectric and Li transport properties of electron conducting and non-conducting sputtered amorphous Ta2O5 films2001Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 46, nr 13-14, s. 2041-2046Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two types of sputtered thin film amorphous tantalum oxide (Ta2O5) were studied: one electron conducting Ta2O5 (ec-Ta2O5) and the other non-conducting Ta2O5 (nc-Ta2O5). The as-deposited films were characterized by impedance spectroscopy (IS) and isothermal transient ionic current (ITIC) measurements. From IS, the dc conductivity 2×10−14 S/cm was obtained for the ec-Ta2O5 film at an applied ac potential of 50 mV whereas a value ≤1×10−17 S/cm was obtained for the nc-Ta2O5 film. Li conducting properties were studied using the galvanostatic intermittent titration technique and ITIC measurements on the intercalated samples. Despite the very dissimilar dc conductivities of the as-deposited films, the two Ta2O5 samples showed surprisingly similar Li ion conducting properties for small Li/Ta2O5 ratios. The Li ion mobility was in the range 1.1×10−9–3.0×10−9 cm2/V s for both films. However, the Li storage behaviour as well as the chemical diffusion coefficient differed. For the nc-Ta2O5 film a plateau was observed in the equilibrium potential vs. composition curve for Li/Ta2O5 ratios between 7×10−5 and 2×10−3. This plateau was likely to have been caused by attractive interactions between the intercalated ions, possibly large enough to cause phase separation. The attractive interactions were shown to suppress the chemical diffusion coefficient in this composition range.

  • 36.
    Gelin, Kristina
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi.
    Mihranyan, Albert
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Razaq, Aamir
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Potential controlled anion absorption in a novel high surface area composite of Cladophora cellulose and polypyrrole2009Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 54, nr 12, s. 3394-3401Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The electrochemical properties of a novel composite paper material of high surface area consisting of polypyrrole (PPy) deposited on cellulose derived from Cladophora sp. algae have been investigated in electrolytes containing different concentrations of nitrate, chloride and p-toluene sulfonate, as well as in solutions containing both p-toluene sulfonate and chloride. The oxidation mechanism and the dependence of the oxidation behavior of the polypyrrole, which was obtained by oxidation of pyrrole with iron(III) chloride, on the anion type and concentration have been studied. Current nucleation maxima, appearing at different times depending on the anion concentration, were obtained during the oxidation of the reduced polymers as a result of the combined action of the formation and growth of conducting polymer strands and anion diffusion. No loss of capacity was seen during repeated oxidation and reduction of the polymer indicating that trapping of anions in the reduced polymer did not limit the electroactivity of the present material. The latter can be explained by the thin polymer layer present on the cellulose substrate. During the oxidation of the polymer, the anions most likely first cover most of the surface of the composite before diffusing into the bulk of the polymer. The estimated distance between these surface sites was also found to match the size of the anions. For electrolytes containing a mixture of anions, the oxidation charge depends on the concentration and size of the different anions.

    The combination of the thin polymer coating and the large specific surface area of the composite give rise to a high ion absorption capacity even for large anions. Hence, the investigated material should be well-suited for use in biotechnological applications involving, e.g., desalting and extraction of proteins and DNA from biological samples.

  • 37.
    Granqvist, Claes Göran
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Arvizu, Miguel A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Bayrak Pehlivan, Ilknur
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Qu, Hui-Ying
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Harbin Institute of Technology, School of Chemistry and Chemical Engineering, MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, Harbin, China.
    Wen, Rui-Tao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Electrochromic materials and devices for energy efficiency and human comfort in buildings: A critical review2018Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 259, s. 1170-1182Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Electrochromic (EC) materials can be integrated in thin-film devices and used for modulating optical transmittance. The technology has recently been implemented in large-area glazing (windows and glass facades) in order to create buildings which combine energy efficiency with good indoor comfort. This critical review describes the basics of EC technology, provides a case study related to EC foils for glass lamination, and discusses a number of future aspects. Ample literature references are given with the object of providing an easy entrance to the burgeoning research field of electrochromics.

  • 38. Guo, Wei
    et al.
    Shen, Yihua
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi.
    Ma, Tingli
    Influence of nitrogen dopants on N-doped TiO2 electrodes and their applications in dye-sensitized solar cells2011Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 56, nr 12, s. 4611-4617Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three different types of nanocrystalline, N-doped TiO2 electrodes were synthesized using several nitrogen dopants through wet methods. The obtained nanocrystalline, N-doped TiO2 electrodes possessed different crystallite sizes, surface areas, and N-doping amounts. Characterizations were performed to reveal the nitrogen-doping processes for the wet methods using ammonia, urea, and triethylamine as the nitrogen dopants. Additionally, a high conversion efficiency of 8.32% was achieved by the dye-sensitized solar cells, based on the N-doped TiO2 electrodes. For instance, in comparison with the commercial P25 (5.76%) and pure anatase TiO2 electrodes (7.14%), significant improvements (44% and 17%, respectively) in the efficiencies were obtained. The findings also indicated that the ammonia nitrogen dopant was more efficient than other two nitrogen dopants. The electron transports, electron lifetimes, and charge recombination in the dye-sensitized N-doped TiO2 solar cells also differed from those in the pure TiO2-based dye-sensitized solar cells (DSCs). Specifically, an enhanced photocurrent of ca. 36% in N-doped DSCs resulted from the synergistic effects of the high dye uptake and the efficient electron transport. Moreover, the relationship between charge and voltage revealed that less charge was needed to get a high open-circuit voltage in the N-doping films.

  • 39.
    Högström, Jonas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Andersson, Matilda
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Björefors, Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    On the evaluation of corrosion resistances of amorphous chromium carbide thin-films2014Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 122, nr SI, s. 224-233Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The possibilities of evaluating the corrosion resistance of amorphous chromium carbide (Cr-C) films containing nanometre-sized carbide grains embedded in an amorphous carbon matrix on the basis of polarization curves, voltammograms and the oxidation charge have been studied for Cr-C films with different carbon concentrations. The films, which were manufactured by non-reactive directcurrent magnetron sputtering, were studied in 1.0 mM H2SO4 at both 22 °C and 80 °C, and with scanning electron microscopy and X-ray photoelectron spectroscopy prior to and after the electrochemical experiments. It is demonstrated that the oxidation of these Cr-C films gives rise to a surface composed of Cr2O3 and partially oxidized carbon and that the non-corroding oxidation current due to the carbon oxidation increases with increasing carbon concentration in the films as well as with the electrolyte temperature. Since the oxidation current is composed of contributions from both Cr-C and carbon oxidation it is not straightforward to evaluate the corrosion resistances of these films based on the current in the passive region, the mixed potential (i.e., the corrosion potential) or the open circuit potential. The present results in fact indicate that Cr-C films with high carbon concentrations may have better corrosion resistances than the corresponding films with lower carbon concentrations although larger currents in the passive region can be seen in polarization curves.

  • 40.
    Jeschull, Fabian
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Lacey, Matthew J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Functional binders as graphite exfoliation suppressants in aggressive electrolytes for lithium-ion batteries2015Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 175, s. 141-150Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A comparative study of various electrode binders for graphite electrodes was conducted in a carbonate-based electrolyte with a high content of propylene carbonate (PC) as a means to evaluate anode degradation in presence of different binders. Because of its direct contact with the active material, a binder can be interpreted as an interfacial layer and as a local part of the electrolyte, the properties of which greatly depend on the interaction with the liquid electrolyte. In this work we demonstrate how a carefully chosen binder can create a specific surface environment that can protect graphite from exfoliation when the binder exhibits poor solubility in the electrolyte solvent and good surface adhesion to the active material. The exceptional stability of graphite electrodes containing poly(acrylic acid) sodium salt (PAA-Na) and carboxymethyl cellulose sodium salt (CMC-Na), respectively, in a PC-rich electrolyte is explained through the understanding of binder swelling and functionality. Interfacial resistances and electrochemical stability were investigated with impedance spectroscopy and galvanostatic cycling. Electrode morphologies and distributions of material were analysed with SEM and EDX. Evidence is presented that the surface selectivity increases with concentration of functional groups and polymer flexibility. Therefore only the less selective, stiff polymer with less functional groups, CMC-Na, provides sufficient protection at low binder contents.

  • 41.
    Johansson, Patrik
    et al.
    Chalmers Univ. of Technol., Gothenburg, Sweden.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Polymer Electrolytes (ISPE 2016)2017Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 247, s. 564-568Artikkel i tidsskrift (Fagfellevurdert)
  • 42.
    Karacic, Dalibor
    et al.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia.
    Korac, Selma
    Univ Sarajevo, Fac Sci, Dept Chem, Zmaja Bosne 33-35, Sarajevo 71000, Bosnia & Herceg.
    Dobrota, Ana S.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia.
    Pasti, Igor A.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia;KTH Royal Inst Technol, Dept Mat Sci & Engn, Sch Ind Engn & Management, Brinellvagen 23, S-10044 Stockholm, Sweden.
    Skorodumova, Natalia V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi. KTH Royal Inst Technol, Dept Mat Sci & Engn, Sch Ind Engn & Management, Brinellvagen 23, S-10044 Stockholm, Sweden.
    Gutic, Sanjin J.
    Univ Sarajevo, Fac Sci, Dept Chem, Zmaja Bosne 33-35, Sarajevo 71000, Bosnia & Herceg.
    When supporting electrolyte matters: Tuning capacitive response of graphene oxide via electrochemical reduction in alkali and alkaline earth metal chlorides2019Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 297, s. 112-117Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ability to tune charge storage properties of graphene oxide (GO) is of utmost importance for energy conversion applications. Here we show that the electrochemical reduction of GO is highly sensitive to the cations present in the solution. GO is reduced at more negative potential in alkali metal chloride solutions than in alkaline earth metal chlorides. During the reduction, the capacitance of GO increases from 10 to 70 times. The maximum capacitances of reduced GO are between 65 and 130 F g-1, depending on the electrolyte and the presence of conductive additive. We propose that different interactions of cations with oxygen functional groups of GO during the reduction are responsible for the observed effect. This hypothesis has been confirmed by Density Functional Theory calculations of alkali and alkaline earth metals interactions with epoxy-functionalized graphene sheet.

  • 43.
    Karlsson, Christoffer
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Huang, Hao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Gogoll, Adolf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Syntetisk organisk kemi.
    Sjödin, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Ion- and Electron Transport in Pyrrole/Quinone Conducting Redox Polymers Investigated by In Situ Conductivity Methods2015Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 179, s. 336-342Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Polypyrrole functionalized with redox active pendant groups constitutes a so called conducting redox polymer, and functions both as a conducting polymer and as a redox polymer. The electrochemical response reveals capacitive charging of the conducting backbone as well as redox cycling of the pendant groups. While the backbone provides an electrically conducting matrix for fast electron transport through the material, the pendant groups offer a large charge storage capacity, much greater than that of polypyrrole itself. We have investigated such polypyrrole-hydroquinone conducting redox polymers, with focus on their in situ conductivity during electrochemical cycling, in order to understand the charge transport mechanisms in this type of system. The most notable feature is that oxidation of the pendant groups leads to a large decrease in the polymer conductivity. The causes of this phenomenon are discussed, as well as the rate limitations of fast redox cycling of the polymer, which are investigated through a combination of bipotentiostat cyclic voltammetry and potential steps of polymer films on interdigitated array electrodes.

  • 44.
    Kasemaegi, Heiki
    et al.
    Univ Tartu, Inst Technol, Tartu, Estonia..
    Ollikainen, Madis
    Univ Tartu, Inst Technol, Tartu, Estonia..
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Aabloo, Alvo
    Univ Tartu, Inst Technol, Tartu, Estonia..
    Molecular Dynamics Modelling of Block-Copolymer Electrolytes with High t(+) Values2015Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 175, s. 47-54Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Molecular Dynamics simulations of the BAB type triblock copolymer lithium poly[(4-styrenesulfonyl) (trifluoromethylenesulfonyl) imide)]-block-poly(ethylene oxide)-block-lithium poly[(4-stryrenesylfonyl) (trifluoromethanesulfonyl) imide] (P(STFSILi)-b-PEO-b-P(STFSILi)) were carried out for different simulation temperatures and B-block lengths. By covalently binding the anion to the polymer backbone, it is immobilised and the cation transference number thereby raised significantly. It was found that the Li-ion diffusion decreases exponentially with growth of the B-block length. The poly(ethylene oxide) matrix dissolves Li-ions already during the equilibration stage of the simulation, and no Li-ion diffusion pathways were identified along the STFSI branches, which significantly influence the transport properties of the material.

  • 45.
    Kavan, Ladislav
    et al.
    Acad Sci Czech Republ, Vvi, J Heyrovsky Inst Phys Chem, Dolejskova 3, CZ-18223 Prague 8, Czech Republic.;Swiss Fed Inst Technol, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland..
    Krysova, Hana
    Acad Sci Czech Republ, Vvi, J Heyrovsky Inst Phys Chem, Dolejskova 3, CZ-18223 Prague 8, Czech Republic..
    Janda, Pavel
    Acad Sci Czech Republ, Vvi, J Heyrovsky Inst Phys Chem, Dolejskova 3, CZ-18223 Prague 8, Czech Republic..
    Tarabkova, Hana
    Acad Sci Czech Republ, Vvi, J Heyrovsky Inst Phys Chem, Dolejskova 3, CZ-18223 Prague 8, Czech Republic..
    Saygili, Yasemin
    Swiss Fed Inst Technol, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Freitag, Marina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Swiss Fed Inst Technol, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland.
    Zakeeruddin, Shaik M.
    Swiss Fed Inst Technol, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland..
    Hagfeldt, Anders
    Swiss Fed Inst Technol, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Gratzel, Michael
    Swiss Fed Inst Technol, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland..
    Novel highly active Pt/graphene catalyst for cathodes of Cu(II/I)-mediated dye-sensitized solar cells2017Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 251, s. 167-175Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Novel highly active, optically-transparent electrode catalyst containing Pt, PtOx, graphene oxide and stacked graphene platelet nanofibers is developed for a cathode of Cu(II/I)-mediated dye-sensitized solar cells. The catalyst layer is deposited on a FTO substrate, which thus becomes smoother than the parent FTO, but the button-like Pt/PtOx nanoparticles are still distinguishable. The found electrocatalytic activity for the Cu(tmby)(2)(2+/+) redox couple (tmby is 4,4', 6,6'-tetramethyl-2,2'-bipyridine) is outperforming that of alternative catalysts, such as PEDOT or platinum. Exchange current densities exceeding 20 mA/cm(2) are provided exclusively by our novel catalyst. The synergic boosting of electrocatalytic activity is seen, if we normalize it to the catalytic performance of individual components, i.e. Pt and graphene nanofibers. The outstanding properties of our cathode are reflected by the performance of the corresponding solar cells using the Y123-sensitized titania photoanode. Champion solar-conversion efficiency (11.3% at 0.1 sun) together with a fill factor of 0.783 compare favorably to all other so far reported best values for this kind of solar cells and the given experimental conditions.

  • 46.
    Kavan, Ladislav
    et al.
    Acad Sci Czech Republic, Vvi, J Heyrovsky Inst Phys Chem, Dolejskova 3, CZ-18223 Prague 8, Czech Republic.;Swiss Fed Inst Technol, Inst Chem Sci & Engn, Lab Photon & Interfaces, CH-1015 Lausanne, Switzerland..
    Saygili, Yasemin
    Swiss Fed Inst Technol, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Freitag, Marina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Swiss Fed Inst Technol, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Zakeeruddin, Shaik M.
    Swiss Fed Inst Technol, Inst Chem Sci & Engn, Lab Photon & Interfaces, CH-1015 Lausanne, Switzerland..
    Hagfeldt, Anders
    Swiss Fed Inst Technol, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Gratzel, Michael
    Swiss Fed Inst Technol, Inst Chem Sci & Engn, Lab Photon & Interfaces, CH-1015 Lausanne, Switzerland..
    Electrochemical Properties of Cu(II/I)-Based Redox Mediators for Dye-Sensitized Solar Cells2017Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 227, s. 194-202Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three Cu(II/I)-phenanthroline and Cu(II/I)-bipyridine redox mediators are studied on various electrodes and in variety of electrolyte solutions using cyclic voltammetry and impedance spectroscopy on symmetrical dummy cells. Graphene-based catalysts provide comparably high activity to PEDOT, and both catalysts outperform the activity of platinum. The charge-transfer kinetics and the diffusion rate significantly slowdown in the presence 4-tert-butylpyridine. This effect is specific only for Cu-mediators (is missing for Co-mediators), and is ascribed to a sensitivity of the coordination sphere of the Cu(II)-species to structural and substitutional changes. The 'Zombie Cells' made from symmetrical PEDOT/PEDOT devices exhibit enhanced charge-transfer rate and enhanced diffusion resistance. Electrochemically clean Cu(II)-bipyridine species are prepared, for the first time, by electrochemical oxidation of the parent Cu(I) complexes. Our preparative electrolysis brings numerous advantages over the standard chemical syntheses of the Cu(II)-bipyridine complexes. The superior performance of electrochemically grown clean Cu(II)-bipyridine complex is demonstrated on practical dye-sensitized solar cells. (C) 2016 Elsevier Ltd. All rights reserved.

  • 47.
    Kostela, Johan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Elmgren, Maja
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Almgren, Mats
    Electrochemistry and diffusion of a redox active surfactant in bicontinuous cubic and lamellar phase2005Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 50, nr 16-17, s. 3333-3340Artikkel i tidsskrift (Fagfellevurdert)
  • 48.
    Lee, Tian Khoon
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. Univ Kebangsaan Malaysia, Fuel Cell Inst, Bangi 43600, Selangor, Malaysia.
    Zaini, Nur Farahidayu Mohd
    Univ Kebangsaan Malaysia, Fac Sci & Technol, Sch Chem Sci & Food Technol, Bangi 43600, Selangor, Malaysia.
    Mobarak, Nadharatun Naiim
    Univ Kebangsaan Malaysia, Fac Sci & Technol, Sch Chem Sci & Food Technol, Bangi 43600, Selangor, Malaysia.
    Hassan, Nur Hasyareeda
    Univ Kebangsaan Malaysia, Fac Sci & Technol, Sch Chem Sci & Food Technol, Bangi 43600, Selangor, Malaysia.
    Noor, Siti Aminah Mohd
    Natl Def Univ Malaysia, Ctr Def Fdn Studies, Chem Dept, Kuala Lumpur 57000, Malaysia.
    Mamat, Shuhib
    Univ Kebangsaan Malaysia, Solar Energy Res Inst, Bangi 43600, Selangor, Malaysia.
    Loh, Kee Shyuan
    Univ Kebangsaan Malaysia, Fuel Cell Inst, Bangi 43600, Selangor, Malaysia.
    KuBulat, Ku Halim
    Univ Malaysia Terengganu, Sch Fundamental Sci, Kuala Nerus 21030, Terengganu, Malaysia.
    Su'ait, Mohd Sukor
    Univ Kebangsaan Malaysia, Solar Energy Res Inst, Bangi 43600, Selangor, Malaysia.
    Ahmad, Azizan
    Univ Kebangsaan Malaysia, Fac Sci & Technol, Sch Chem Sci & Food Technol, Bangi 43600, Selangor, Malaysia.
    PEO based polymer electrolyte comprised of epoxidized natural rubber material (ENR50) for Li-Ion polymer battery application2019Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 316, s. 283-291Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Solid polymer electrolytes (SPE) of poly (ethylene oxide) (PEO) - 50% epoxidized natural rubber (ENR50) polymer blend doped with lithium bis(trifluoromethanesulfonyl) imide salt (LiTFSI) have achieved an optimum ionic conductivity value of 6.45 x 10(-5) S cm(-1) at 25 wt % of LiTFSI salt (room temperature). The chronoamperometry analysis indicated that the charge transport in polymer electrolyte is near-dominated by ion with lithium transference numbers (T-Li(+)) of 0.29. Notably, this electrolyte exhibits a good electrochemical stability of 4.2 V (vs. Li/Li+). Further investigation by IR has indicated that polymer-salt complexation occurred between Li+ from dopant salt with oxygen from the ether group (C-O-C). These have weaken the vibrational mode of methylene group (CH2); scissoring and rocking mode on plane as well as twisting mode for out of the plane. The strong complexation between the cations with the polymeric segments have indirectly increased the thermal stability of the polymer electrolytes. Nevertheless, using the facile blending method, the addition of environment benign and natural material of ENR50 has improved the PEO-based electrolyte system. 

  • 49.
    Liivat, Anti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    New crystalline NaAsF(6)-PEO(8) complex: A Density Functional Theory study2011Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 57, s. 244-249Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    DFT calculations of new polymer salt complex NaAsF(6)center dot PEO(8) have been carried out in its low-temperature (LT) phase for the purpose of understanding the relationship between the structure and ionic transport in this material. Both relaxation at OK and finite-temperature ab initio molecular dynamics approach up to 273 K reproduced the LT structure very well. Nudged elastic band method has been used for estimating the migration barriers for collective migration of cations or anions in PEO tunnel-direction. The migration barriers were 1.25 eV per anion and 1.6 eV per cation which could explain the lower t(+) value as reported from experiments. AsF(6)(-) anion exhibits rotational disorder about the three crystallographic directions of which the y-direction is least hindered.

  • 50.
    Liivat, Anti
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Thomas, Josh
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Guo, Jianghuai
    Xiamen Univ, Dept Chem, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China..
    Yang, Yong
    Xiamen Univ, Dept Chem, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China..
    Novel insights into higher capacity from the Li-ion battery cathode material Li2FeSiO42017Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 223, s. 109-114Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A highly reactive composite cathode material incorporating nano-particles of the popular Li-ion battery cathode material Li2FeSiO4 (LFS) is here studied to probe the activation of the controversial Fe3+/Fe4+ redox couple in exploiting the second Li-ion in the formula unit - for use in rechargeable Li-ion batteries. A novel form of in situ Mossbauer spectroscopy is used to monitor the oxidation state of the Fe-ions in symmetric LFS LFS cells. This is based on mapping the poorly resolvable Mossbauer spectra from the expected Fe3+/Fe4+ redox couple in the working electrode onto the highly resolvable Fe2+/Fe3+ spectra from the counter electrode. Comparison of such data from half-delithiated Li(1)Fe3+SiO4 parallel to Li(1)Fe3+SiO4 and almost lithium-free "Li(0)Fe4+SiO4 parallel to Li(0)Fe4+SiO4" symmetric cells is demonstrated - to distinguish the electrode reactions from the those involving the electrolyte. Lithium is shown to cycle reversibly in the symmetric cells. However, a large proportion of the cycled lithium (similar to 70%) does not derive from the bulk of the electrodes, but is rather a result of high-V electrolyte degradation, where charge balance is maintained by leaching lithium from the electrolyte and inserting it into the electrodes.

12 1 - 50 of 92
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf