Acid resistant PVDF-co-HFP based copolymer proton exchange membrane for electro-chemical application

Abstract Acid resistant proton exchange membranes (PEMs) are synthesized from aliphatic highly hydrophobic polyvinylidene-co-hexafluoropropylene (PVDF-co-HFP) and aromatic hydrophilic sodium- p -styrene sulfonate at nanostructure level modification. Synthesized copolymer PEMs are analyzed for their chemical structure to confirm the presence of functional groups. Electrochemical characterizations are carried out in terms ion-exchange capacity, ionic conductivity and water content. Maximum IEC value 1.91 meq/gm is observed for PDSt-40 copolymer PEM with 1.58 × 10 −2 S/cm proton conductivity and 29.1% of water content. Vanadium ion permeability is also checked for copolymer membranes in terms of applicability for vanadium redox flow batteries. PDSt-40 copolymer PEM shows lowest value of VO 2+ ion permeability 2.87 × 10 −7 cm 2 min −1 , which is about 40% less compared to Nafion membrane. Further all synthesized PEMs are checked for charging-discharging performance for single cell VRFB. PDSt-40 PEM shows better performance in term of columbic and voltage efficiency. Copolymer membranes found to be stable thermally and mechanically and also in harass condition with 18 M H 2 SO 4 for 24 h. Results indicate that synthesized copolymer PEMs can be a good candidate for electrochemical energy systems as well as high temperature applications.