New substantially fluorinated ionomers for electrochemical applications

Novel, substantially fluorinated ionomers based on vinylidene fluoride copolymers deliver attractive properties for lithium ion battery applications. This ionomer family exhibits excellent compatibility with electrode components, high affinity for carbonate solvents, flexibility in fabrication methods, and good ionic conductivity of solvent-swollen gel films. Controlled feed of microfluidized liquid sulfonyl fluoride comonomer allows for the production of random and compositionally tapered copolymers exhibiting features of block or graft-block structures. Post-polymerization functional group transformations include sulfonate salt and sulfonyl dicyanomethide salt formation as key processes for making ionomers having high ionic conductivity. Single-crystal X-ray structure analyses of model systems CF3SO3Li and LiPF6, in the form of discrete solvates, provide a unifying view of lithium ion coordination in these systems.