Binary Solvophilic/Solvophobic Network-Based Nonswelling Hybrid Electrolytes for Stable Lithium-Metal Batteries

Abstract

Nowadays, in the transition stage between the liquid electrolyte and solid electrolyte, the lean electrolyte strategy developed based on ceramic-polymer composite electrolytes (CPEs) has important practical significance to make up for their shortcomings and realize coordinated improvement of safety performance and electrochemical performance. However, the lean electrolyte CPE system is seriously limited by the contradiction between ion transport and swelling of polymer components in CPEs in practical applications. Polymers with high ionic conductivity tend to absorb the few liquid electrolytes and subsequently swell, resulting in reduced electrode wettability and electrical properties, while polymers that do not swell usually have poor ionic conductivity, reducing the intrinsic conductivity of CPEs. Herein, a binary solvophilic/solvophobic polymer network of CPEs is constructed under lean electrolyte condition. As a solvophilic segment, the urea-functionalized poly(propylene oxide) can not only improve the Li + transport capacity but also form hydrogen bonds with the fluorine on the solvophobic poly(vinylidene fluoride-co-trifluoroethylene) (PVDF−TrFE) segment, thereby forming a hydrophobic composite network at the molecular scale. Then, the epoxidized Li 1+x Al x Ti 2−x (PO 4 ) 3 (LATP) is further cross-linked with the urea amino groups on the polymer chain. This can significantly inhibit swelling and improve the ion transmission performance, endowing lithium-metal batteries with excellent electrochemical properties.