Urea chain extension reinforced high-elastic polymer electrolyte for solid-state lithium metal batteries

Solid polymer electrolytes have attracted much attention due to they can greatly improve the energy density and safety performance of batteries. However, solid polymer electrolytes suffer from low ionic conductivity and poor interfacial stability, so solving the problems of ionic conductivity and high elasticity of solid polymer electrolytes to cope with volume expansion remains a challenge. Herein, a highly elastic polyurea electrolyte was prepared, which was crosslinked by urea chain extension and epoxy ring-opening polymerization. The high polarity of urea group made the electrolyte have high ionic conductivity of 4.4 × 10−4 S cm−1 and high ion migration number of 0.76, and its excellent mechanical properties. In particular, the high resilience can effectively resist the volume expansion problem during the battery cycle. The capacity retention rate of the prepared Li| polyurea-CPE-10%SN |LiFePO4 battery reached 75 % after 500 cycles at 1 C and 25 °C.