Electrolyte Anion-Initiated In Situ Polymerization of Dioxolane-Derived Gel Electrolytes for Dendrite-Resistant and Separator-Free Lithium Metal Batteries
Tianyu Shen, Qianchuan Yu, Jie Wei, Yaoda Wang, Huaizhu Wang, Zhenchao Li, Xingkai Ma, Jingjie Sun, Jing Ma, Zuoxiu Tie, Zhong Jin
Abstract
The practicality of solid-state lithium metal batteries is limited by poor interfacial contact and low ion conductivity of solid-state electrolytes. Herein, we report a gel polymer electrolyte composed of LiN(SO 2 F) 2 and polymerized dioxolane prepared via in situ ring-opening polymerization triggered by radicals without the need for additional initiators and separators. Theoretical and experimental studies revealed a polymerization mechanism involving S–F bond rupture in LiN(SO 2 F) 2, followed by attack of a Lewis-acidic S atom in the •(SO 2 )(FSO 2 )N – radical on a Lewis-basic O atom in dioxolane. The electrolyte demonstrated high ion conductivity (1.836 mS cm –1 ) and Li-ion transference number (0.705), significantly improving the Li plating/stripping uniformity and long-term stability. Batteries with such electrolytes exhibited high-rate capability, high Coulombic efficiency, high capacity retention (75.1% after 3000 cycles), and broad temperature tolerance (−15 to 70 °C). Our research underscores the potential of in situ polymerization in fabricating gel polymer electrolytes to promote the development of secondary alkali metal batteries with exceptional energy density and stability.