Fire retardant, superionic solid state polymer electrolyte membranes for lithium ion batteries

Recent advances on polymer electrolyte membranes (PEM) are reviewed with emphasis on fabrication and evaluation of electrochemical performance of solid PEMs consisted of photo-curable polymer precursor, lithium salt, and solid plasticizer. Guided by the phase diagram of ternary mixtures of poly(ethylene glycol) derivatives, lithium bis(trifluoromethane)sulfony imide (LiTFSI) salt, and succinonitrile (SCN) plasticizer, the achievement of completely amorphous, solid PEMs has been demonstrated. These solid PEM films are stretchable, thermally stable, and flame-retardant, showing enhanced high ionic conductivity on the level of superionic conductors. Electrochemical stability of the PEM has been tested in half-cell configurations using LiFePO4 and Li4Ti5O12 electrodes against lithium foil counter electrode and their future prospects are discussed.