A wide-temperature superior ionic conductive polymer electrolyte for lithium metal battery

Abstract

Abstract Polymer electrolytes are one of promising candidates that can meet the demands of high safety and stability of high-energy lithium metal batteries. However, the practical applications of polymer electrolytes are usually limited by the low ionic conductivity, narrow electrochemical window and highly interfacial resistance. Here we designed a poly(vinyl ethylene carbonate) polymer electrolyte for polymer lithium metal battery by in-situ polymerization method. The new polymer electrolyte provides superior ionic conductivity with 2.1 × 10−3 S cm−1 at 25 °C, wide electrochemical window up to 4.5 V (vs. Li+/Li) and excellent interfacial compatibility to electrodes. The ions transports are mainly achieved from the coupling/decoupling between Li ions and oxygen atoms in C O groups, partially from the coupling/decoupling between Li+ and oxygen atoms in C–O groups, and probably moving/exchange of Li+ between C O and C–O groups in the process of segmental motions in high and low molecular polymers of polymer electrolyte. The lithium metal batteries with LiFePO4 cathode can deliver a high discharge capacity of ~165 mA h g−1 at 25 °C, and even ~104 mA h g−1 at −15 °C with current density of 0.1C. Therefore, the novel polymer electrolyte designed in this study is a promising candidate for high performances polymer lithium metal batteries.