Electroactive Polymer Based Porous Membranes for Energy Storage Applications
Wide ranges of materials properties for cathode, anode and battery separator/electrolyte are being developments for improving characteristics and performance of the battery.
The battery separator is essential in electrochemical cells, separating the anode and cathode and controling the number and mobility of the lithium ions.
Among the materials most investigated for battery separators are the PVDF and its copolymers poly(vinylidene fluoride-co-trifluoroethylene), PVDF-TrFE, poly(vinylidene fluoride-co-hexafluoropropylene), PVDF-HFP, and poly(vinylidene fluoride-cochlorotrifluoroethylene),PVDF-CTFE .
These materials show strong advantages for their use as separator membranes in comparison to polyolefins due to their high dipolar moment and large dielectric constant for a polymer material, which can assist ionization of lithium salts.
In this work, PVDF and its copolymers have been processed by solvent cast technique with varying solvent evaporation temperature and the polymer/solvent ratio with the objective to tailor degree of porosity, mechanical, thermal and electrical properties.
Degree of porosity, uptake, tortuosity, degree of crystallinity and ionic conductivity of the different membranes are evaluated and their influence in lithium-ion battery performance presented and discussed.
This work is funded by FEDER funds through the “Programa Operacional Factores de Competitividade—COMPETE” and by national funds from FCT—Fundação para a Ciência e a Tecnologia, in the framework of the Strategic Project PEST-C/FIS/UI607/2011, project F-COMP-01-0124-FEDER-022716 and grant SFRH/BD/68499/2010 (C.M.C.). The authors also thank funding from Matepro –Optimizing Materials and Processes”, ref. NORTE-07-0124-FEDER-000037”, co-funded by the “Programa Operacional Regional do Norte” (ON.2 – O Novo Norte), under the “Quadro de Referência Estratégico Nacional” (QREN), through the “Fundo Europeu de Desenvolvimento Regional” (FEDER).
The authors thank Celgard LLC, Timcal, Solvay, Arkema and Clariant for kindly supplying their high quality membranes and excellent materials, respectively.
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