Fig. 1: Challenges and requirements of QSSEs in solid-state batteries.

a Oxidation of VEC, VC and PEGMA in high-voltage positive electrode cells. b Unclear Li-migration mechanism in polymer-based quasi-solid-state electrolytes (QSSE). c Late release of liquid on the interface with Li-metal and increased resistance. d The requirements of desired QSSEs in high-voltage cells. e The cost comparison of various solid electrolytes, including sulfide electrolytes, oxide electrolytes, polymer, and Li-salt. All price was calculated from industrial products in Chinese Yuan (¥).