Two-Dimensional Template Induced Ultradense Solid Polymer Electrolytes for High-Performance Solid-State Lithium Batteries

Solid polymer electrolytes based on PVDF-HFP (SPEs) hold great promise in the application of solid-state Li metal batteries (SSLMBs). However, phase-separation-induced inadequate mechanical robustness and compromised Li⁺ transport kinetics significantly hinder their industrial application. Herein, negatively charged Ti_0.87O₂ monolayer nanosheets were introduced as an interconnected template to suppress phase separation and guide the formation of an ultradense PVDF-HFP electrolyte (UDSPE) with enhanced mechanical properties. Besides, the strong interaction between Ti_0.87O₂ nanosheets and Li⁺ enables the rapid Li⁺ migration through the interface, resulting in high ionic conductivity (0.87 mS cm⁻¹). The homogeneously dispersed LiTFSI facilitates the formation of an inorganic solid electrolyte interphase, thus effectively suppressing interfacial side reactions and enhancing the interface stability. Consequently, the symmetric cell exhibits a 2300 h stable cycling, and the Li||LiFePO₄ full cell with UDSPE demonstrates a stable cycling performance for more than 2000 cycles. Remarkably, Ah level solid state pouch cell with a high energy density of 386 Wh kg⁻¹ was assembled and worked without any liquid addition. This work provides a rational strategy for designing high-aspect-ratio nanosheet templates to achieve homogeneous polymer electrolytes and enable high-performance SSLMBs.