Built-in single-ion-conducting polymer bridges for superior ion transport enabling long-life and high-voltage lithium–metal batteries

Abstract

Composite polymer electrolyte (CPE)-based Li metal batteries have emerged as the most promising candidates for next-generation batteries. However, intrinsic incompatibility between composite phases severely compromises electrolyte performance. Herein, we propose a built-in single-ion-conductor bridge that seamlessly links the garnet-type oxide phase with PVDF-based polymer matrixes, enabling excellent composite compatibility and superior Li⁺ fluxes throughout the bulk electrolyte. The 2-acrylamido-2-methylpropanesulfonic acid molecule is chosen to in situ convert the inert surface layer of garnet fast-ion conductors into a molecular single-ion-conducting layer with rapid ionic transport, effectively bridging ion transport among multiple components. The resulting CPE exhibits remarkable long-cycling stability under extreme conditions (e.g., high voltage of 4.5 V, high loading of 10.2 mg cm⁻², and low temperature of −30 °C). Specifically, the assembled Li‖LiNi_0.9Co_0.05Mn_0.05O₂ pouch cells delivered a stable cycling for 1200 cycles at 0.5C. Moreover, the strategy is readily applicable to sodium metal batteries, achieving decay-free performance over 2200 cycles. Thus, it offers a promising approach for fabricating high-performance solid-state batteries.