Flame-retardant composite gel polymer electrolyte with a dual acceleration conduction mechanism for lithium ion batteries

Abstract

In recent years, the pursuit of high electrochemical stability and safety are considered as the newly growing and leading trend of next-generation lithium-ion batteries (LIB). The gelation of polymer electrolytes(GPEs) is the most direct and effective way to improve electrochemical performance. Herein, a novel composited polyethylene glycol (PEG) electrolyte is reported with a dual acceleration conduction effect of Li+ by the nano-TiO2 and triethyl phosphate (TEP). The negative ZETA potential of nano-TiO2/PEG internal interface promoted the dissociation of lithium salt by the unstable adsorption in diffusion layer, which enhanced the lithium ion migration and promoted the uniformity of lithium deposition. The flame retardant TEP improved safety performance, adjusted the affinity between EO and Li+, which bestowed it a high discharge 125.7mAh/g at 0.2C, with a low average capacity decay rate of 0.08% per cycle. The well-designed PEG-TEP-TiO2 GPEs showed wide electrochemical window, stable Li+ stripping/plating, smaller voltage polarizations and excellent cycling performance. The new understanding of composite electrolytes provides a powerful avenue for facilitating the gelation-solid-state lithium ion batteries.