Phase regulation to obtain dense composite polymer-based electrolytes for high-voltage solid-state lithium metal batteries

Abstract Solid polymer electrolytes are accepted as promising candidates for solid-state lithium metal batteries due to the flexibility and large-scale manufacturability. In particular, poly(vinylidene fluoride)-based polymer electrolytes with unique “salt-polymer-trace residual solvent” configuration exhibit attractive for batteries’ room-temperature operations. However, the porous structure and the still limited ionic conductivity prevent their further advancement. Herein, we proposed a phase regulation strategy to disrupt the symmetry of PVDF chains by coupling with ferroelectric MoSe 2 sheets, in which the asymmetric adsorption interactions result in the formation of all trans (TTTT) conformation of PVDF and dense structure of composite electrolyte. The developed β-phase-rich electrolyte provides a high dielectric environment to optimize the solvation structures that form abundant solvent-separated ion pairs, achieving high ionic conductivity (6.5×10 − 4 S cm − 1 ) with low activation energy (0.07 eV). Further, the in-situ reactions between MoSe 2 and Li metal construct fast conductor Li 2 Se in the interfaces, which significantly enhances the interfacial transport kinetics and electrochemical stability. Therefore, the Li||Li cells achieve record cycling of 480 hours at 1 mA cm − 2 , and the Li||LiNi 0.8 Co 0.1 Mn 0.1 O 2 full cells show ultra-long lifespan of 2000 times at 3C. This work provides an encouraging strategy contributing to large-scale production towards their practical applications.