Binary Solvophilic/Solvophobic\nNetwork-Based Nonswelling\nHybrid Electrolytes for Stable Lithium-Metal Batteries

Abstract

Nowadays, in the transition stage between the liquid\nelectrolyte\nand solid electrolyte, the lean electrolyte strategy developed based\non ceramic-polymer composite electrolytes (CPEs) has important practical\nsignificance to make up for their shortcomings and realize coordinated\nimprovement of safety performance and electrochemical performance.\nHowever, the lean electrolyte CPE system is seriously limited by the\ncontradiction between ion transport and swelling of polymer components\nin CPEs in practical applications. Polymers with high ionic conductivity\ntend to absorb the few liquid electrolytes and subsequently swell,\nresulting in reduced electrode wettability and electrical properties,\nwhile polymers that do not swell usually have poor ionic conductivity,\nreducing the intrinsic conductivity of CPEs. Herein, a binary solvophilic/solvophobic\npolymer network of CPEs is constructed under lean electrolyte condition.\nAs a solvophilic segment, the urea-functionalized poly(propylene oxide)\ncan not only improve the Li⁺ transport capacity but also\nform hydrogen bonds with the fluorine on the solvophobic poly(vinylidene\nfluoride-<i>co</i>-trifluoroethylene) (PVDF–TrFE)\nsegment, thereby forming a hydrophobic composite network at the molecular\nscale. Then, the epoxidized Li_1+<i>x</i>Al_<i>x</i>Ti_2–<i>x</i>(PO₄)₃ (LATP) is further cross-linked with the urea\namino groups on the polymer chain. This can significantly inhibit\nswelling and improve the ion transmission performance, endowing lithium-metal\nbatteries with excellent electrochemical properties.