Polyvinylidene fluoride, or polyvinylidene difluoride, (PVDF) is a highly non-reactive thermoplastic fluoropolymer produced by the polymerization of vinylidene difluoride.
P 7121 (OTTO) Poly(vinylidene fluoride) average Mw ~534,000 by GPC Cas 24937-79-9 - used because it is chemically inert over the potential range used, and does not react with the electrolyte or lithium.