In Situ Polymerized Flame‐Retardant Crosslinked Quasi Solid‐State Electrolytes for High‐Voltage Lithium Metal Batteries

Abstract The construction of poly‐dioxolane (PDOL) solid‐state electrolytes by in situ polymerization is an effective way to achieve high performance lithium‐metal batteries. However, the poor electrochemical stability and safety issues of linear PDOL limit their further application. In this work, a multifunctional crosslinker has been introduced to construct a flame retardant crosslinked quasi solid‐state electrolyte (FCDOL). Due to the synergistic effect of the crosslinked network, the prepared FCDOL achieves excellent room temperature ionic conductivity (0.72 mS cm −1 ), high Li + transference number (0.655), wide electrochemical stabilization window (4.8 V vs Li/Li + ), and impressive performance when matched with lithium metal anodes (>4000 h plating/stripping) and high‐voltage cathodes, and the corresponding pouch cells can withstand abusive tests such as bending and cutting, encouraging that in situ polymerization of SPEs provides new insights into high‐energy density and high‐safety solid‐state batteries.