Molecular structure adjustment enhanced anti-oxidation ability of polymer electrolyte for solid-state lithium metal battery

Abstract

Poly(vinyl ethylene carbonate) (PVEC) electrolyte is one of the preferable choices for solid-state lithium metal batteries (SSLMBs). However, the poor anti-oxidation ability still hinders its practical application for high-energy SSLMBs with high-voltage cathodes. Herein, the strategy of molecular structure adjustment is proposed for improving the properties of PVEC, which exhibits the widened electrochemical stability window (4.8 V vs. Li+/Li) and high ionic conductivity (1.1 × 10−3 S cm1 at 25 °C). The compatibilities of cathode/electrolyte and anode/electrolyte interfaces are also enhanced respectively by eliminating the weak bonding of polymer molecular structure and forming LixSn alloy during the ring-opening polymerization. The solid-state batteries with LiCoO2 cathode exhibit the high capacity when charged to 4.5 V at 25 °C. Therefore, this work not only demonstrates the effective method to enhance the interfacial compatibility between electrolyte and electrode, but also affords an emerging design strategy for polymer electrolyte by breaking the unstable weak bonding for the application requirements of SSLMBs.