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  • 1.
    Asfaw, Habtom D.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Valvo, Mario
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Maibach, Julia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Ångström, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Tai, Cheuk-Wai
    Bacsik, Zoltan
    Sahlberg, Martin
    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.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Boosting the thermal stability of emulsion–templated polymers via sulfonation: an efficient synthetic route to hierarchically porous carbon foams2016Inngår i: ChemistrySelect, ISSN 2365-6549, Vol. 1, nr 4, s. 784-792Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hierarchically porous carbon foams with specific surface areas exceeding 600 m2 g−1 can be derived from polystyrene foams that are synthesized via water-in-oil emulsion templating. However, most styrene-based polymers lack strong crosslinks and are degraded to volatile products when heated above 400 oC. A common strategy employed to avert depolymerization is to introduce potential crosslinking sites such as sulfonic acids by sulfonating the polymers. This article unravels the thermal and chemical processes leading up to the conversion of sulfonated high internal phase emulsion polystyrenes (polyHIPEs) to sulfur containing carbon foams. During pyrolysis, the sulfonic acid groups (-SO3H) are transformed to sulfone (-C-SO2-C-) and then to thioether (-C−S-C-) crosslinks. These chemical transformations have been monitored using spectroscopic techniques: in situ IR, Raman, X-ray photoelectron and X-ray absorption near edge structure spectroscopy. Based on thermal analyses, the formation of thioether links is associated with increased thermal stability and thus a substantial decrease in volatilization of the polymers.

  • 2.
    Asfaw, Habtom Desta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Multifunctional Carbon Foams by Emulsion Templating: Synthesis, Microstructure, and 3D Li-ion Microbatteries2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Carbon foams are among the existing electrode designs proposed for use in 3D Li-ion microbatteries. For such electrodes to find applications in practical microbatteries, however, their void sizes, specific surface areas and pore volumes need be optimized. This thesis concerns the synthesis of highly porous carbon foams and their multifunctional applications in 3D microbatteries. The carbon foams are derived from polymers that are obtained by polymerizing high internal phase water-in-oil emulsions (HIPEs).

    In general, the carbonization of the sulfonated polymers yielded hierarchically porous structures with void sizes ranging from 2 to 35 µm and a BET specific surface area as high as 630 m2 g-1. Thermogravimetric and spectroscopic evidence indicated that the sulfonic acid groups, introduced during sulfonation, transformed above 250 oC to thioether (-C-S-) crosslinks which were responsible for the thermal stability and charring tendency of the polymer precursors. Depending on the preparation of the HIPEs, the specific surface areas and void-size distributions were observed to vary considerably. In addition, the pyrolysis temperature could also affect the microstructures, the degree of graphitization, and the surface chemistry of the carbon foams.

    Various potential applications were explored for the bespoke carbon foams. First, their use as freestanding active materials in 3D microbatteries was studied. The carbon foams obtained at 700 to 1500 oC suffered from significant irreversible capacity loss during the initial discharge. In an effort to alleviate this drawback, the pyrolysis temperature was raised to 2200 oC. The resulting carbon foams were observed to deliver high, stable areal capacities over several cycles. Secondly, the possibility of using these structures as 3D current collectors for various active materials was investigated in-depth. As a proof-of-concept demonstration, positive active materials like polyaniline and LiFePO4 were deposited on the 3D architectures by means of electrodeposition and sol-gel approach, respectively. In both cases, the composite electrodes exhibited reasonably high cyclability and rate performance at different current densities. The syntheses of niobium and molybdenum oxides and their potential application as electrodes in microbatteries were also studied. In such applications, the carbon foams served dual purposes as 3D scaffolds and as reducing reactants in the carbothermal reduction process. Finally, a facile method of coating carbon substrates with oxide nanosheets was developed. The approach involved the exfoliation of crystalline VO2 to prepare dispersions of hydrated V2O5, which were subsequently cast onto CNT paper to form oxide films of different thicknesses.

    Delarbeid
    1. Boosting the thermal stability of emulsion–templated polymers via sulfonation: an efficient synthetic route to hierarchically porous carbon foams
    Åpne denne publikasjonen i ny fane eller vindu >>Boosting the thermal stability of emulsion–templated polymers via sulfonation: an efficient synthetic route to hierarchically porous carbon foams
    Vise andre…
    2016 (engelsk)Inngår i: ChemistrySelect, ISSN 2365-6549, Vol. 1, nr 4, s. 784-792Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Hierarchically porous carbon foams with specific surface areas exceeding 600 m2 g−1 can be derived from polystyrene foams that are synthesized via water-in-oil emulsion templating. However, most styrene-based polymers lack strong crosslinks and are degraded to volatile products when heated above 400 oC. A common strategy employed to avert depolymerization is to introduce potential crosslinking sites such as sulfonic acids by sulfonating the polymers. This article unravels the thermal and chemical processes leading up to the conversion of sulfonated high internal phase emulsion polystyrenes (polyHIPEs) to sulfur containing carbon foams. During pyrolysis, the sulfonic acid groups (-SO3H) are transformed to sulfone (-C-SO2-C-) and then to thioether (-C−S-C-) crosslinks. These chemical transformations have been monitored using spectroscopic techniques: in situ IR, Raman, X-ray photoelectron and X-ray absorption near edge structure spectroscopy. Based on thermal analyses, the formation of thioether links is associated with increased thermal stability and thus a substantial decrease in volatilization of the polymers.

    Emneord
    Emulsion-templated polymer, sulfonation, pyrolysis, spectroscopy, carbon foam
    HSV kategori
    Forskningsprogram
    Kemi med inriktning mot materialkemi
    Identifikatorer
    urn:nbn:se:uu:diva-283174 (URN)10.1002/slct.201600139 (DOI)000395395900026 ()
    Prosjekter
    3D microbatteries
    Tilgjengelig fra: 2016-04-11 Laget: 2016-04-11 Sist oppdatert: 2017-10-30bibliografisk kontrollert
    2. Emulsion-templated bicontinuous carbon network electrodes for use in 3D microstructured batteries
    Åpne denne publikasjonen i ny fane eller vindu >>Emulsion-templated bicontinuous carbon network electrodes for use in 3D microstructured batteries
    2013 (engelsk)Inngår i: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 1, nr 44, s. 13750-13758Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    High surface area carbon foams were prepared and characterized for use in 3D structured batteries. Twopotential applications exist for these foams: firstly as an anode and secondly as a current collector supportfor electrode materials. The preparation of the carbon foams by pyrolysis of a high internal phase emulsionpolymer (polyHIPE) resulted in structures with cage sizes of 25 mm and a surface area enhancement pergeometric area of approximately 90 times, close to the optimal configuration for a 3D microstructuredbattery support. The structure was probed using XPS, SEM, BET, XRD and Raman techniques; revealingthat the foams were composed of a disordered carbon with a pore size in the <100 nm range resultingin a BET measured surface area of 433 m2 g-1. A reversible capacity exceeding 3.5 mA h cm2 at acurrent density of 0.37 mA cm-2 was achieved. SEM images of the foams after 50 cycles showed thatthe structure suffered no degradation. Furthermore, the foams were tested as a current collector bydepositing a layer of polyaniline cathode over their surface. High footprint area capacities of500 mA h cm-2 were seen in the voltage range 3.8 to 2.5 V vs. Li and a reasonable rate performancewas observed.

    sted, utgiver, år, opplag, sider
    United Kingdom: , 2013
    Emneord
    Carbon foam, High internal phase emulsion polymer, microbattery, 3D microbattery, Lithium ion
    HSV kategori
    Forskningsprogram
    Materialvetenskap; Kemi; Materialvetenskap; Fysikalisk kemi
    Identifikatorer
    urn:nbn:se:uu:diva-210659 (URN)10.1039/C3TA12680C (DOI)000326463400009 ()
    Prosjekter
    STEM-VR-Microbattery
    Forskningsfinansiär
    Swedish Energy AgencySwedish Research Council
    Tilgjengelig fra: 2013-11-12 Laget: 2013-11-12 Sist oppdatert: 2017-12-06bibliografisk kontrollert
    3. Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteries
    Åpne denne publikasjonen i ny fane eller vindu >>Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteries
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Emneord
    carbon, foam, graphitic, anode, three-dimensional, microbattery, lithium
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-312893 (URN)
    Forskningsfinansiär
    Swedish Research Council, 2012–4681StandUp
    Tilgjengelig fra: 2017-01-14 Laget: 2017-01-14 Sist oppdatert: 2017-12-30
    4. Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance
    Åpne denne publikasjonen i ny fane eller vindu >>Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance
    Vise andre…
    2014 (engelsk)Inngår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, nr 15, s. 8804-8813Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol–gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm−2 at 0.1 mA cm−2 (lowest rate) and 1.1 mA h cm−2 at 6 mA cm−2(highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.

    sted, utgiver, år, opplag, sider
    Royal Society of Chemistry: , 2014
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-228630 (URN)10.1039/C4NR01682C (DOI)000339861500051 ()
    Prosjekter
    STEM-VR-Microbattery
    Tilgjengelig fra: 2014-07-18 Laget: 2014-07-18 Sist oppdatert: 2017-12-05bibliografisk kontrollert
    5. Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteries
    Åpne denne publikasjonen i ny fane eller vindu >>Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteries
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Emneord
    niobium, oxide, nanoparticle, power, energy, carbon, foam, lithium, microbattery
    HSV kategori
    Forskningsprogram
    Kemi med inriktning mot materialkemi
    Identifikatorer
    urn:nbn:se:uu:diva-312894 (URN)
    Prosjekter
    3D Lithium-ion microbattery
    Forskningsfinansiär
    Swedish Research Council, 2012–4681StandUp
    Tilgjengelig fra: 2017-01-14 Laget: 2017-01-14 Sist oppdatert: 2017-12-30
    6. A one-step water based strategy for synthesizing hydrated vanadium pentoxide nanosheets from VO2(B) as free-standing electrodes for lithium battery applications
    Åpne denne publikasjonen i ny fane eller vindu >>A one-step water based strategy for synthesizing hydrated vanadium pentoxide nanosheets from VO2(B) as free-standing electrodes for lithium battery applications
    Vise andre…
    2016 (engelsk)Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 46, s. 17988-18001Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The synthesis of two dimensional (2D) materials from transition metal oxides, chalcogenides, and carbides mostly involve multiple exfoliation steps in which hazardous solvents and reagents are used. In this study, hydrated vanadium pentoxide (V2O5[middle dot]nH2O) nanosheets with a thickness of a few nanometers were prepared via a facile environmentally friendly water based exfoliation technique. The exfoliation process involved refluxing the precursor, vanadium dioxide (VO2(B)), in water for a few days at 60 [degree]C. The proposed exfoliation mechanism is based on the intercalation/insertion of water molecules into the VO2(B) crystals and the subsequent cleavage of the covalent bonds holding the layers of VO2(B) together. The thermal and chemical analyses showed that the approximate chemical composition of the nanosheets is H0.4V2O5[middle dot]0.55H2O, and the percentage of VV content to that of VIV in the nanosheets is about 80(3)% to 20(3)%. The exfoliated aqueous suspension of the V2O5[middle dot]0.55H2O nanosheets was successfully deposited onto multi-walled carbon nanotube (MW-CNT) paper to form free-standing electrodes with a thickness of the V2O5[middle dot]0.55H2O layer ranging between 45 and 4 [small mu ]m. A series of electrochemical tests were conducted on the electrodes to determine the cyclability and rate capability of lithium insertion into V2O5[middle dot]0.55H2O nanosheets. The electrodes with the thinnest active material coating ([similar]4 [small mu ]m) delivered gravimetric capacities of up to 480 and 280 mA h g-1 when cycled at current densities of 10 and 200 mA g-1, respectively.

    Emneord
    2D materials, vanadium oxides, free-standing, battery, lithium
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-311357 (URN)10.1039/C6TA06571F (DOI)000388505400010 ()
    Forskningsfinansiär
    Swedish Research Council, 2012-4681Swedish Energy AgencyBerzelii Centre EXSELENTStandUp
    Tilgjengelig fra: 2016-12-24 Laget: 2016-12-24 Sist oppdatert: 2017-12-30
  • 3.
    Asfaw, Habtom Desta
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Kotronia, Antonia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Tai, Cheuk-Wai
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius laboratory, Stockholm, Sweden.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Tailoring the Microstructure and Electrochemical Performance of 3D Microbattery Electrodes Based on Carbon Foams2019Inngår i: Energy Technology, ISSN 0829-7681, E-ISSN 2057-4215, Vol. 7, nr 10, artikkel-id UNSP 1900797Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three‐dimensional (3D) carbon electrodes with suitable microstructural features and stable electrochemical performance are required for practical applications in 3D lithium (Li)‐ion batteries. Herein, the optimization of the microstructures and electrochemical performances of carbon electrodes derived from emulsion‐templated polymer foams are dealt with. Exploiting the rheological properties of the emulsion precursors, carbon foams with variable void sizes and specific surface areas are obtained. Carbon foams with an average void size of around 3.8 μm are produced, and improvements are observed both in the coulombic efficiency and the cyclability of the carbon foam electrodes synthesized at 2200 °C. A stable areal capacity of up to 1.22 mAh cm−2 (108 mAh g−1) is achieved at a current density of 50 μA cm−2. In addition, the areal capacity remains almost unaltered, i.e., 1.03 mAh cm−2 (91 mAh g−1), although the cycling current density increases to 500 μA cm−2 indicating that the materials are promising for power demanding applications.

  • 4.
    Asfaw, Habtom Desta
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Roberts, Matthew R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Tai, Cheuk-Wai
    Stockholm University.
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. DTU.
    Valvo, Mario
    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.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance2014Inngår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, nr 15, s. 8804-8813Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol–gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm−2 at 0.1 mA cm−2 (lowest rate) and 1.1 mA h cm−2 at 6 mA cm−2(highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.

  • 5.
    Asfaw, Habtom Desta
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Roberts, Matthew R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. St. Andrews.
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. DTU.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Emulsion-templated bicontinuous carbon network electrodes for use in 3D microstructured batteries2013Inngår i: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 1, nr 44, s. 13750-13758Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High surface area carbon foams were prepared and characterized for use in 3D structured batteries. Twopotential applications exist for these foams: firstly as an anode and secondly as a current collector supportfor electrode materials. The preparation of the carbon foams by pyrolysis of a high internal phase emulsionpolymer (polyHIPE) resulted in structures with cage sizes of 25 mm and a surface area enhancement pergeometric area of approximately 90 times, close to the optimal configuration for a 3D microstructuredbattery support. The structure was probed using XPS, SEM, BET, XRD and Raman techniques; revealingthat the foams were composed of a disordered carbon with a pore size in the <100 nm range resultingin a BET measured surface area of 433 m2 g-1. A reversible capacity exceeding 3.5 mA h cm2 at acurrent density of 0.37 mA cm-2 was achieved. SEM images of the foams after 50 cycles showed thatthe structure suffered no degradation. Furthermore, the foams were tested as a current collector bydepositing a layer of polyaniline cathode over their surface. High footprint area capacities of500 mA h cm-2 were seen in the voltage range 3.8 to 2.5 V vs. Li and a reasonable rate performancewas observed.

  • 6.
    Asfaw, Habtom Desta
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Tai, Cheuk-Wai
    Stockholm University.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteriesManuskript (preprint) (Annet vitenskapelig)
  • 7.
    Asfaw, Habtom Desta
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Tai, Cheuk-Wai
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Over-Stoichiometric NbO2 Nanoparticles for a High Energy and Power Density Lithium Microbattery2017Inngår i: CHEMNANOMAT, ISSN 2199-692X, Vol. 3, nr 9, s. 646-655Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Effective utilization of active materials in microbatteries can be enhanced by rational design of the electrodes. There is an increasing trend of using 3D electrodes that are coated in nanosized active materials to boost both energy and power densities. This article focuses on the fabrication of 3D electrodes based on monolithic carbon foams coated in over-stoichiometric NbO2 nanoparticles. The electrodes exhibit remarkable energy and power densities at various current densities when tested in lithium microbatteries. An areal capacity of around 0.7mAhcm(-2) and energy density up to 45mWhcm(-3) have been achieved. More than half of the areal capacity can be accessed at a current density of about 11mAcm(-2), with the corresponding energy and power densities being 21mWhcm(-3) and 1349mWcm(-3). These values are comparable to those of microsupercapacitors containing carbon and MnO2 nanomaterials. Furthermore, the electrochemical reversibility improves progressively upon cycling along with substantial increase in the charge transfer kinetics of the electrode. Based on impedance analyses almost a fourfold decrease in the charge transfer resistance has been observed over 25 cycles. Such enhancement of the electronic properties of NbO2 can account for the high electrochemical rate performance of the 3D electrodes.

  • 8.
    Asfaw, Habtom Desta
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Tai, Cheuk-Wai
    Stockholm University.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteriesManuskript (preprint) (Annet vitenskapelig)
  • 9.
    Asfaw, Habtom
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Tai, Cheuk-Wai
    Stockholm University.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteriesManuskript (preprint) (Annet vitenskapelig)
  • 10.
    Doubaji, Siham
    et al.
    LCME, University Cadi Ayyad, Marrakech, Morocco.
    Ma, Lu
    Argonne Naional Laboratory.
    Asfaw, Habtom Desta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Izanzar, Ilyasse
    LCME, University Cadi Ayyad, Marrakech, Morocco.
    Xu, Rui
    Argonne National Laboratory.
    Alami, Jones
    Mohammed VI Polytechnic University (UM6P), Ben Guerir, Morocco.
    Lu, Jun
    Argonne National Laboratory.
    Wu, Tianpin
    Argonne National Laboratory.
    Amine, Khalil
    Argonne National Laboratory.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Saadoune, Ismael
    LCME, University Cadi Ayyad, Marrakech, Morocco.; Mohammed VI Polytech Univ UM6P, Mat Sci & Nanoengn Dept, Lot 660 Hay My Rachid, Ben Guerir 43150, Morocco..
    On the P2-NaxCo1−y(Mn2/3Ni1/3)yO2 Cathode Materials for Sodium-Ion Batteries: Synthesis, Electrochemical Performance, and Redox Processes Occurring during the Electrochemical Cycling2018Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, nr 1, s. 488-501Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    P2-type NaMO2sodiated layered oxides withmixed transition metals are receiving considerable attention foruse as cathodes in sodium-ion batteries. A study on solidsolution (1−y)P2-NaxCoO2−(y)P2-NaxMn2/3Ni1/3O2(y=0,1/3, 1/2, 2/3, 1) reveals that changing the composition of thetransition metals affects the resulting structure and the stabilityof pure P2 phases at various temperatures of calcination. For 0≤y≤1.0, the P2-NaxCo(1−y)Mn2y/3Niy/3O2solid-solutioncompounds deliver good electrochemical performance whencycled between 2.0 and 4.2 V versus Na+/Na with improved capacity stability in long-term cycling, especially for electrodematerials with lower Co content (y= 1/2 and 2/3), despite lower discharge capacities being observed. The (1/2)P2-NaxCoO2−(1/2)P2-NaxMn2/3Ni1/3O2composition delivers a discharge capacity of 101.04 mAh g−1with a capacity loss of only 3% after 100cycles and a Coulombic efficiency exceeding 99.2%. Cycling this material to a higher cutoffvoltage of 4.5 V versus Na+/Naincreases the specific discharge capacity to≈140 mAh g−1due to the appearance of a well-defined high-voltage plateau, but afteronly 20 cycles, capacity retention declines to 88% and Coulombic efficiency drops to around 97%. In situ X-ray absorption near-edge structure measurements conducted on composition NaxCo1/2Mn1/3Ni1/6O2(y= 1/2) in the two potential windows studiedhelp elucidate the operating potential of each transition metal redox couple. It also reveals that at the high-voltage plateau, all ofthe transition metals are stable, raising the suspicion of possible contribution of oxygen ions in the high-voltage plateau.

  • 11.
    Etman, Ahmed S.
    et al.
    Stockholms Universitet.
    Asfaw, Habtom D.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Yuan, Ning
    Stockholm University and SLU.
    Li, Jian
    Peking University, China.
    Zhou, Zhengyang
    Peking University.
    Peng, Fei
    Stockholm University.
    Persson, Ingmar
    Swedish University of Agricultural Sciences.
    Zou, Xiaodong
    Stockholm University.
    Gustafsson, Torbjörn
    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 and Peking University.
    A one-step water based strategy for synthesizing hydrated vanadium pentoxide nanosheets from VO2(B) as free-standing electrodes for lithium battery applications2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 46, s. 17988-18001Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The synthesis of two dimensional (2D) materials from transition metal oxides, chalcogenides, and carbides mostly involve multiple exfoliation steps in which hazardous solvents and reagents are used. In this study, hydrated vanadium pentoxide (V2O5[middle dot]nH2O) nanosheets with a thickness of a few nanometers were prepared via a facile environmentally friendly water based exfoliation technique. The exfoliation process involved refluxing the precursor, vanadium dioxide (VO2(B)), in water for a few days at 60 [degree]C. The proposed exfoliation mechanism is based on the intercalation/insertion of water molecules into the VO2(B) crystals and the subsequent cleavage of the covalent bonds holding the layers of VO2(B) together. The thermal and chemical analyses showed that the approximate chemical composition of the nanosheets is H0.4V2O5[middle dot]0.55H2O, and the percentage of VV content to that of VIV in the nanosheets is about 80(3)% to 20(3)%. The exfoliated aqueous suspension of the V2O5[middle dot]0.55H2O nanosheets was successfully deposited onto multi-walled carbon nanotube (MW-CNT) paper to form free-standing electrodes with a thickness of the V2O5[middle dot]0.55H2O layer ranging between 45 and 4 [small mu ]m. A series of electrochemical tests were conducted on the electrodes to determine the cyclability and rate capability of lithium insertion into V2O5[middle dot]0.55H2O nanosheets. The electrodes with the thinnest active material coating ([similar]4 [small mu ]m) delivered gravimetric capacities of up to 480 and 280 mA h g-1 when cycled at current densities of 10 and 200 mA g-1, respectively.

  • 12.
    Kotronia, Antonia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Asfaw, Habtom Desta
    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.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    CaS- and MgS-assisted graphitization of porous carbons for energy storage applications2017Konferansepaper (Annet vitenskapelig)
  • 13.
    Kotronia, Antonia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Asfaw, Habtom Desta
    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.
    Brandell, Daniel
    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.
    The Cathode Electrolyte Interphase on Graphite Positive Electrode in Dual-ion Batteries Probed Using X-ray Photoelectron SpectroscopyManuskript (preprint) (Annet vitenskapelig)
  • 14.
    Kotronia, Antonia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Asfaw, Habtom Desta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Tai, Cheuk-Wai
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden.
    Edström, Kristina
    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.
    3D Electrodes Fabricated from Nano-graphitic Carbon Foams with Enhanced Lithium-ion StorageManuskript (preprint) (Annet vitenskapelig)
  • 15.
    Ma, Yue
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Asfaw, Habtom Desta
    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.
    A General Method to Fabricate Free-Standing Electrodes: Sulfonate Directed Synthesis and their Li+ Storage Properties2015Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, nr 11, s. 3957-3965Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For materials based on a spatially varied conversion reaction, Li+ storage properties largely hinge on the rational design of the concurrent electronic and ionic pathways in the electrode. We herein present a scalable approach for integrating size-tunable Fe3O4 nanocrystals with hierarchical porous carbon foam by employing sulfonated high internal phase emulsion polymers (polyHIPE) as the carbon source and substrate. To verify the feasibility of our configuration design, the electrodes of such a type were directly evaluated in pouch cells without using an auxiliary binder or a metallic current collector: The best performing composite electrode, with optimized oxide size range, exhibits a good capacity retention of 89.7% of the first charge capacity after 100 cycles and high rate durability up to 4 A g–1. Furthermore, this synthetic approach was also applied to develop carbon/FeS free-standing anodes using the sulfonate groups as the sulfur source, demonstrating its generic applicability to the fabrication of other free-standing electrodes with enhanced Li+ storage properties.

  • 16.
    Ma, Yue
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Asfaw, Habtom Desta
    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.
    Three-dimensional carbon foam supported tin oxide nanocrystallites with tunable size range: Sulfonate anchoring synthesis and high rate lithium storage properties2015Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 294, s. 208-215Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The development of a free-standing electrode with high rate capability requires the realization of facile electrolyte percolation, fast charge transfer at the electrode-electrolyte interface as well as the intimate electrical wiring to the current collector. Employing a sulfonated high internal phase emulsion polymer (polyHIPE) as the carbon precursor, we developed a free-standing composite of carbon foam encapsulated SnO2 nanocrystallites, which simultaneously satisfies the aforementioned requirements. When directly evaluated in the pouch cell without using the binder, carbon additive or metallic current collector; the best performing composite exhibits a good rate performance up to 8 A g(-1) and very stable cyclability for 250 cycles. This cycling performance was attributed to the synergistic coupling of hierarchical macro/mesoporous carbon foam and SnO2 nanocrystals with optimized size range. Postmortem characterizations unveiled the significant influence of subtle size variation of oxides on the electrochemical performance.

  • 17.
    Ma, Yue
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Asfaw, Habtom Desta
    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.
    Three-dimensional carbon foam supported tin oxide nanocrystallites with tunable size range: sulfonate anchoring synthesis and high rate lithium storage properties2015Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 294, s. 208-15Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The development of a free-standing electrode with high rate capability requires the realization of facile electrolyte percolation, fast charge transfer at the electrode-electrolyte interface as well as the intimate electrical wiring to the current collector. Employing a sulfonated high internal phase emulsion polymer (polyHIPE) as the carbon precursor, we developed a free-standing composite of carbon foam encapsulated SnO 2 nanocrystallites, which simultaneously satisfies the aforementioned requirements. When directly evaluated in the pouch cell without using the binder, carbon additive or metallic current collector, the best performing composite exhibits a good rate performance up to 8 A g -1 and very stable cyclability for 250 cycles. This cycling performance was attributed to the synergistic coupling of hierarchical macro/mesoporous carbon foam and SnO 2 nanocrystals with optimized size range. Postmortem characterizations unveiled the significant influence of subtle size variation of oxides on the electrochemical performance. [All rights reserved Elsevier].

  • 18.
    Ma, Yue
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Asfaw, Habtom Desta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Liu, Chenjuan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Wei, Bingqing
    Centre for Nano Energy Materials, State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China; Department of Mechanical Engineering, University of Delaware, Newark, DE 19716, United States.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Encasing Si particles within a versatile TiO2−xFx layer as an extremely reversible anode for high energy-density lithium-ion battery2016Inngår i: Nano Energy, ISSN 2211-2855, Vol. 30, s. 745-755Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The chemical phenomena occurring at the electrode-electrolyte interfaces profoundly determine the cycle behavior of a lithium ion battery. In this work, we report that silicon-based anodes can attain enhanced levels of capacity retention, rate performance and lifespan when a versatile protective layer of, F-doped anatase (TiO2−xFx), is applied towards taming the interfacial chemistry of the silicon particles. With careful choice of titanium fluoride as a precursor, internal voids can be generated upon in-situ fluoride etching of the native oxide layer and are used to alleviate the mechanical stress caused by volume expansion of silicon during cycling. In the course of F-doping, part of the Ti4+(d0) ions in anatase are reduced to Ti3+(d1), thereby increasing charge carriers in the crystal structure. Hence, the multifunctional F-doped TiO2−x coating, not only minimizes the direct exposure of the Si surface to the electrolyte, but also improves the electronic conductivity via inter-valence electron hopping. The best-performing composite electrode, Si@TiO2−xFx-3, delivered a satisfactory performance in both half-cell and full-cell configurations. Furthermore, we present a study of 1) the Si valence change at the buried interface using synchrotron based hard X-ray photoelectron spectroscopy, and 2) the phase transformation of the electrode monitored in operando using X-ray diffraction. Based on these characterizations, we observe that the Li+ conducting intermediate phase (LixTiO2−xFx) formed inside the surface coating enables deep lithiation and delithiation of the silicon during battery operation, and thus increase the capacity that can be accessed from the electrodes.

  • 19.
    Oltean, Gabriel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Desta Asfaw, Habtom
    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.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    A Li-Ion Microbattery with 3D Electrodes of Different Geometries2014Inngår i: ECS Electrochemistry Letters, ISSN 2162-8734, Vol. 3, nr 6, s. A54-A57Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A Li-ion microbattery comprising three-dimensional (3D) electrodes of different geometries is reported. While aluminum nanorods are used as the negative electrode a 3D carbon matrix with a larger surface area is used as support for the LiFePO4 positive electrode to compensate for the difference in the specific energy densities between LiFePO4 and Al. No difference in cycling behavior was observed for cells containing delithiated (Al) or partially lithiated (LixAl) nanorods as the negative electrode. The present electrode geometry concept is particularly promising for the design of Li-ion microbatteries in which 3D electrode materials with different specific energy densities are employed.

  • 20.
    Priimagi, Priit
    et al.
    Univ Tartu, Inst Technol, IMS Lab, Nooruse 1, EE-50411 Tartu, Estonia.
    Asfaw, Habtom Desta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Srivastav, Shruti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Kasemagi, Heiki
    Univ Tartu, Inst Technol, IMS Lab, Nooruse 1, EE-50411 Tartu, Estonia.
    Aabloo, Alvo
    Univ Tartu, Inst Technol, IMS Lab, Nooruse 1, EE-50411 Tartu, Estonia.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Zadin, Vahur
    Univ Tartu, Inst Technol, IMS Lab, Nooruse 1, EE-50411 Tartu, Estonia.
    Modeling 3D-microbatteries based on carbon foams2018Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 281, s. 665-675Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Porous electrodes are considered attractive for potential use as 3D current collectors in Li-ion microbatteries. Carbon foams, in particular, can be coated with a variety of active materials to prepare electrodes which can maximize energy and power density simultaneously. Modeling such electrodes will aid the selection of microstructural parameters (e.g. porosity) required to optimize their electrochemical performance. Here, experimentally-validated Finite Element Methodology (FEM) is used to simulate a 3D Li-ion microbattery featuring a carbon foam electrode coated by layers of LiFePO4 nanoparticles. The electrodes are cycled against Li-metal at various current densities, and the electrochemical data obtained are used to benchmark and parametrize the simulations. By systematic variation of the LiFePO4 coating thickness and homogeneity and the foam substrate, it is revealed that LiFePO4 exhibits a uniform delithiation process and that the electrochemical reactions favor particles closer to the carbon structure, which is due to the poor electrical conductivity of LiFePO4. Therefore, the cell capacity (mAh cm(-2)) per footprint area can be increased by using lower charging currents, smaller carbon macropore sizes and thicker LiFePO4 coatings. The porous carbon structure provides an excellent template for loadings of LiFePO4 material, which in turn allows using thicker coatings with improved cell performance.

  • 21.
    Sun, Bing
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. Paul Scherrer Inst, Electrochem Lab, Electrochem Energy Storage Sect, CH-5232 Villigen, Switzerland.
    Asfaw, Habtom Desta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. Imperial Coll London, Dept Chem, London SW7 2AZ, England.
    Rehnlund, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Mindemark, Jonas
    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.
    Edström, Kristina
    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.
    Towards Solid-State 3D-Microbatteries using Functionalized Polycarbonate-based Polymer Electrolytes2018Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, nr 3, s. 2407-2413Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    3D-microbatteries (3D-MBs) impose new demands for theselection, fabrication and compatibility of the different battery components, notleast the electrolytes. Herein, solid polymer electrolytes (SPEs) based on poly(trimethylene carbonate) (PTMC) have been implemented in 3D-MB systems. 3D electrodes of two different architectures, LiFePO4-coated carbon foams and Cu2O-coated Cu nanopillars, have been coated with SPEs and used in Li-cells. Functionalized PTMC with hydroxyl end groups was found to enable uniform and well-covering coatings on LiFePO4-coated carbon foams, although the cell cycling performance was limited by the large SPE resistance. By employing a SPE prepared from a copolymer of TMC and caprolactone (CL), with higher ionic conductivity, Li-cells composed of Cu2O-coated Cu nanopillars were constructed and tested both at room temperature and 60 °C. The footprint areal capacity of the cells was ca. 0.02 mAh cm-2 for an area gain factor (AF) of 2.5, and 0.2 mAh cm-2 for a relatively dense nanopillar-array (AF=25) at a current density of 0.008 mA cm-2at ambient temperature (22±1 °C). These results provide new routes towards the realization of all-solid-state 3D-MBs.

1 - 21 of 21
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