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  • 1.
    Bergfelt, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Mogensen, Ronnie
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lacey, Matthew
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Guiomar, Hernández
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Bowden, Tim
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Mechanically Robust and Highly Conductive Di-Block Copolymers as Solid Polymer Electrolytes for Room Temperature Li-ion Batteries2018Conference paper (Other academic)
    Abstract [en]

    Alternative solid polymer electrolytes (SPEs) hosts to the archetype poly(ethylene oxide) are gaining attention thanks to their appealing properties, such as higher cation transport number, thermal stability and electrochemical stability [1]. In addition, high mechanical stability is required in order to integrate easy-to-use materials into flexible or ‘structural’ batteries [2, 3].

     In this work, a solid polymer electrolyte (SPE) featuring high ionic conductivity and mechanical robustness at room temperature is presented. The SPE consists of a di-block copolymer, poly(benzyl methacrylate)-poly(ε-caprolactone-r-trimethylene carbonate) (BCT), mixed with different loadings of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The highest ionic conductivity achieved for these SPEs was found with 16.7 wt% LiTFSI loading (BCT17), reaching 9.1 x 10-6 S cm-1 at 30 °C. The limited current fraction (F+) for the BCT17 electrolyte was calculated to be 0.64 with the Bruce-Vincent method. Furthermore, dynamic mechanical analysis showed a storage modulus (E’) of 0.2 GPa below 40 °C and 1 MPa above 50 °C. These results indicate that BCT with LiTFSI is a competitive electrolyte, combining high ionic conductivity and modulus at ambient temperatures.

     LiFePO4|BCT17|Li half-cells showed good cycling performance at 60 °C. At 30 °C, where the SPE possessed significantly higher modulus, decent cell performance could still be achieved after several optimization steps. These included incorporating a SPE as binder, and infiltration cast the SPE on the electrode to maximize the contact between both components, thereby improving the interfacial contact and decreasing the cell resistance and overpotential when cycling the battery device.

     References

    [1] J. Mindemark, M.J. Lacey, T. Bowden, D. Brandell. Prog Polym Sci, (2018). DOI: 10.1016/j.progpolymsci.2017.12.004.

    [2] J.F. Snyder, R.H. Carter, E.D. Wetzel. Chem Mater, 19 (2007) 3793-801.

    [3] W.S. Young, W.F. Kuan, Thomas H. Epps. J Polym Sci, Part B: Polym Phys, 52 (2014) 1-16.

  • 2.
    Hernández, Guiomar
    et al.
    Univ Basque Country UPV EHU, POLYMAT, Joxe Mari Korta Ctr, Avda Tolosa 72, Donostia San Sebastian 20018, Spain.
    Lago, Nerea
    Univ Basque Country UPV EHU, POLYMAT, Joxe Mari Korta Ctr, Avda Tolosa 72, Donostia San Sebastian 20018, Spain.
    Shanmukaraj, Devaraj
    CIC EnergiGUNE, Alava Technol Pk,Albert Einstein 48, Minano 01510, Alava, Spain.
    Armand, Michel
    CIC EnergiGUNE, Alava Technol Pk,Albert Einstein 48, Minano 01510, Alava, Spain.
    Mecerreyes, David
    Ikerbasque, Basque Fdn Sci, E-48011 Bilbao, Spain;Univ Basque Country UPV EHU, POLYMAT, Joxe Mari Korta Ctr, Avda Tolosa 72, Donostia San Sebastian 20018, Spain.
    Polyimide-polyether bindersediminishing the carbon content in lithium-sulfur batteries2017In: MATERIALS TODAY ENERGY, ISSN 2468-6069, Vol. 6, p. 264-270Article in journal (Refereed)
    Abstract [en]

    Lithium-sulfur batteries are on the run to become the next generation energy storage technology. First of all due to its high theoretical energy density but also for its sustainability and low cost. However, there are still several challenges to take into account such as reducing the shuttle effect, decreasing the amount of conductive carbon to increase the energy density or enhancing the sulfur utilization. Herein, redox-active binders based on polyimide-polyether copolymers have been proposed as a solution to those drawbacks. These multiblock copolymers combine the ability of poly (ethylene oxide) to act as polysulfide trap and the properties of the imide groups to redox mediate the charge-discharge of sulfur. Thus, poly (ethylene oxide) block helps with the shuttle effect and mass transport in the electrode whereas the polyimide part enhances the charge transfer promoting the sulfur utilization. Sulfur cathodes containing pyromellitic, naphthalene or perylene polyimide-polyether binders featured improved cell performance in comparison with pure PEO binder. Among them, the electrode with naphthalene polyimide-PEO binder showed the best results with an initial capacity of 1300 mA h g(-1) at C/5, low polarization and 70% capacity retention after 30 cycles. Reducing the amount of carbon black in the cathode to 5 wt%, the cell with the redox-active binder was able to deliver 500 mA h g(-1) at C/5 with 78% capacity retention after 20 cycles. Our results demonstrate the possibility to reduce the amount of carbon by introducing polyimide-polyether copolymers as redox-active binders, increasing the sulfur utilization, redox kinetics and stability of the cell. (C) 2017 Elsevier Ltd. All rights reserved.

  • 3.
    Hernández, Guiomar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Naylor, Andrew J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Non-Fluorinated Electrolytes for Si-based Li-ion Battery Anodes2018Conference paper (Other academic)
    Abstract [en]

    Although the performance of lithium-ion batteries has been improved to some extent since the initial commercialization,1 cycling stability, safety and sustainability still present some challenges and concerns. In this regard, the battery electrolyte plays an important role. State-of-the-art electrolytes contain the electrolyte salt LiPF6, susceptible to undergo defluorination reactions and form toxic and corrosive compounds, such as HF. Yet, fluorine-containing electrolytes are often considered necessary for enhanced battery performance. On the other hand, replacing LiPF6 with fluorine-free salts would reduce cost, increase safety and decrease toxicity, both in the manufacturing and recycling processes. Among the available fluorine-free salts, lithium bis(oxalato)borate (LiBOB) is a viable candidate due to its enhanced thermal stability.2 Furthermore, additives in the electrolyte are another common source of fluorine, not least fluoroethylene carbonate (FEC) which can form a stable solid electrolyte interface (SEI).3

    Herein, we compare the cell performance of fluorinated and non-fluorinated electrolytes in NMC/Si-Graphite full cells. Three electrolytes are tested: (1) LP57 (1 M LiPF6 in ethylene carbonate (EC):ethyl methyl carbonate (EMC) 3:7 vol/vol); (2) LP57 with 10 wt% FEC and 2 wt%  vinylene carbonate (VC); and (3) 0.7 M LiBOB in EC:EMC 3:7 vol/vol and 2 wt% VC.

    The cells containing the conventional electrolyte, LP57, feature a rapid capacity fade and continuous decrease in coulombic efficiency. The cell performance is improved when adding SEI-forming additives to the electrolyte (LP57 with FEC and VC). In addition, stable cycling for over 200 cycles are obtained for both the fluorinated (LP57 with FEC and VC) and non-fluorinated (LiBOB with VC) electrolytes.

    Characterisation by X-ray photoelectron spectroscopy (XPS) of the anode surface showed higher amounts of carbonate species and a thicker SEI layer with the non-fluorinated electrolyte compared to the fluorinated one.

    1 J. Electrochem. Soc. 2017, 164, A5019-A5025.

    2 ChemSusChem 2017, 10, 2431-2448.

    3 J. Electrochem. Soc. 2014, 161, A1933-A1938.

  • 4.
    Phadatare, Manisha
    et al.
    Mid Sweden Univ, Dept Nat Sci, SE-85170 Sundsvall, Sweden;Deemed Univ, DY Patil Educ Soc, Ctr Interdisciplinary Res, Kolhapur 416006, Maharashtra, India.
    Patil, Rohan
    Mid Sweden Univ, Dept Nat Sci, SE-85170 Sundsvall, Sweden.
    Blomquist, Nicklas
    Mid Sweden Univ, Dept Nat Sci, SE-85170 Sundsvall, Sweden.
    Forsberg, Sven
    Mid Sweden Univ, Dept Nat Sci, SE-85170 Sundsvall, Sweden.
    Örtegren, Jonas
    Mid Sweden Univ, Dept Nat Sci, SE-85170 Sundsvall, Sweden.
    Hummelgård, Magnus
    Mid Sweden Univ, Dept Nat Sci, SE-85170 Sundsvall, Sweden.
    Meshram, Jagruti
    Deemed Univ, DY Patil Educ Soc, Ctr Interdisciplinary Res, Kolhapur 416006, Maharashtra, India.
    Hernández, Guiomar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Sathyanath, Sharath Kumar Manjeshwar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Olin, Håkan
    Mid Sweden Univ, Dept Nat Sci, SE-85170 Sundsvall, Sweden.
    Silicon-Nanographite Aerogel-Based Anodes for High Performance Lithium Ion Batteries2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 14621Article in journal (Refereed)
    Abstract [en]

    To increase the energy storage density of lithium-ion batteries, silicon anodes have been explored due to their high capacity. One of the main challenges for silicon anodes are large volume variations during the lithiation processes. Recently, several high-performance schemes have been demonstrated with increased life cycles utilizing nanomaterials such as nanoparticles, nanowires, and thin films. However, a method that allows the large-scale production of silicon anodes remains to be demonstrated. Herein, we address this question by suggesting new scalable nanomaterial-based anodes. Si nanoparticles were grown on nanographite flakes by aerogel fabrication route from Si powder and nanographite mixture using polyvinyl alcohol (PVA). This silicon-nanographite aerogel electrode has stable specific capacity even at high current rates and exhibit good cyclic stability. The specific capacity is 455 mAh g(-1) for 200th cycles with a coulombic efficiency of 97% at a current density 100 mA g(-1).

  • 5.
    Xu, Chao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Univ Cambridge, Dept Chem, Lensfield Rd, Cambridge CB2 1EW, England.
    Hernández, Guiomar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Abbrent, Sabina
    Czech Acad Sci, Inst Macromol Chem, Heyrovskeho Nam 2, Prague 16206 6, Czech Republic.
    Kober, Libor
    Czech Acad Sci, Inst Macromol Chem, Heyrovskeho Nam 2, Prague 16206 6, Czech Republic.
    Konefal, Rafal
    Czech Acad Sci, Inst Macromol Chem, Heyrovskeho Nam 2, Prague 16206 6, Czech Republic.
    Brus, Jiri
    Czech Acad Sci, Inst Macromol Chem, Heyrovskeho Nam 2, Prague 16206 6, Czech Republic.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Unraveling and Mitigating the Storage Instability of Fluoroethylene Carbonate-Containing LiPF6 Electrolytes To Stabilize Lithium Metal Anodes for High-Temperature Rechargeable Batteries2019In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, no 7, p. 4925-4935Article in journal (Refereed)
    Abstract [en]

    Implementing Li metal anodes provides the potential of substantially boosting the energy density of current Li-ion battery technology. However, it suffers greatly from fast performance fading largely due to substantial volume change during cycling and the poor stability of the solid electrolyte interphase (SEI). Fluoroethylene carbonate (FEC) is widely acknowledged as an effective electrolyte additive for improving the cycling performance of batteries consisting of electrode materials that undergo large volume changes during cycling such as Li metal. In this study, we report that while FEC can form a robust SEI on the electrode, it also deteriorates the shelf life of electrolytes containing LiPF6. The degradation mechanism of LiPF6 in FEC solutions is unraveled by liquid-and solid-state NMR. Specifically, traces of water residues induce the hydrolysis of LiPF6, releasing HF and PF5 which further trigger ring-opening of FEC and its subsequent polymerization. These reactions are significantly accelerated at elevated temperatures leading to the formation of a three-dimensional fluorinated solid polymer network. Moisture scavenger additives, such as lithium 4,5-dicyano-2-(trifluoromethyl)imidazole (LiTDI), can delay the degradation reaction as well as improve the cycling stability of LiNi1/3Mn1/3Co1/3O2/Li metal batteries at 55 degrees C. This work highlights the poor shelf life of electrolytes containing FEC in combination with LiPF6 and thereby the great importance of developing proper storage methods as well as optimizing the content of FEC in practical cells.

  • 6.
    Åkerlund, Lisa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Emanuelsson, Rikard
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Hernández, Guiomar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ruipérez, F.
    Casado, N.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mecerreyes, D.
    Sjödin, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    The proton trap battery: Enabling reversible hydroquinone energy storage in organic electrolytes2019In: Organic Battery Days 2019., 2019Conference paper (Refereed)
  • 7.
    Åkerlund, Lisa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Emanuelsson, Rikard
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Hernández, Guiomar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ruipérez, Fernando
    Casado, Nerea
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mecerreyes, David
    Sjödin, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    In situ Investigations of a Proton Trap Material: A PEDOT-Based Copolymer with Hydroquinone and Pyridine Side Groups Having Robust Cyclability in Organic Electrolytes and Ionic Liquids2019In: ACS Applied Energy Materials, ISSN 2574-0962, Vol. 2, no 6, p. 4486-4495Article in journal (Refereed)
    Abstract [en]

    A conducting redox polymer based on PEDOT with hydroquinone and pyridine pendant groups is reported and characterized as a proton trap material. The proton trap functionality, where protons are transferred from the hydroquinone to the pyridine sites, allows for utilization of the inherently high redox potential of the hydroquinone pendant group (3.3 V versus Li0/+) and sustains this reaction by trapping the protons within the polymer, resulting in proton cycling in an aprotic electrolyte. By disconnecting the cycling ion of the anode from the cathode, the choice of anode and electrolyte can be extensively varied and the proton trap copolymer can be used as cathode material for all-organic or metal-organic batteries. In this study, a stable and nonvolatile ionic liquid was introduced as electrolyte media, leading to enhanced cycling stability of the proton trap compared to cycling in acetonitrile, which is attributed to the decreased basicity of the solvent. Various in situ methods allowed for in-depth characterization of the polymer’s properties based on its electronic transitions (UV–vis), temperature-dependent conductivity (bipotentiostatic CV-measurements), and mass change (EQCM) during the redox cycle. Furthermore, FTIR combined with quantum chemical calculations indicate that hydrogen bonding interactions are present for all the hydroquinone and quinone states, explaining the reversible behavior of the copolymer in aprotic electrolytes, both in three-electrode setup and in battery devices. These results demonstrate the proton trap concept as an interesting strategy for high potential organic energy storage materials.

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