Developing lithiated polyvinyl formal based single-ion conductor membrane with a significantly improved ionic conductivity as solid-state electrolyte for batteries.

A novel lithiated polyvinyl formal single-ion conductor (Li-PVFM) membrane has been proposed and prepared as polymer electrolyte for Li-ion batteries with excellent mechanical strength of 11–34 MPa and good thermal stability, but the series faces the common issue of solid-state electrolyte - a low ionic conductivity about 10 −6 S cm −1 at room temperature. Herein, by purifying the polymer matrix to avoid the negative effect of the impurities on Li + diffusion, and linking more Li + from lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) on the matrix to improve the carrier concentration, the as obtained solid-state electrolyte membrane exhibits a significantly improved ambient ionic conductivity in two orders of magnitude to 10 −4 S cm −1 . The results confirm that the polymer matrix is obtained without any residual oxalate and carbonate, resulting in the increasing ionic conductivity of electrolyte membrane from 10 −6 to 10 −5 S cm −1 . Furthermore, the conductor membrane with modulating the lithium content to 0.80 mol L −1 has a high lithium-ion transference number of 0.81, wide electrochemical stability window of > 5 V (vs. Li + /Li) and excellent tensile strength of 44.8 MPa. The solid electrolyte batteries using LiFePO 4 as cathode material exhibit a reversible capacity of 130 mAh g −1 and a good cycling stability. [ABSTRACT FROM AUTHOR]