Composite electrolytes engineered by anion acceptors for boosted high-voltage solid-state lithium metal batteries

Solid-state batteries (SSBs) are considered as the most promising option to replace commercial lithium-ion batteries due to their ability to address the flammability of liquid organic electrolytes and facilitate the energy density of lithium batteries. Herein, by introducing tris(trimethylsilyl) borate (TMSB) as anion acceptors, we successfully develop the light and thin electrolyte (TMSB-PVDF-HFP-LLZTO-LiTFSI, PLFB) with a wide voltage window to couple the lithium metal anode with the high-voltage cathodes. Consequently, as-prepared PLFB can greatly boost the generation of free Li⁺ and improve the Li⁺ transference numbers (t_Li+=0.92) at room temperature. Moreover, combined with theoretical calculation and experimental results, the changes in the composition and properties of the composite electrolyte membrane with the addition of anionic receptors are systematically studied, which further implies the intrinsic mechanism of the stability difference. In addition, the PLFB-based SSB assembled by LiNi_0.8Co_0.1Mn_0.1O₂ cathode and lithium anode exhibits a high capacity retention of 86% after loop 400 cycles. This investigation on boosted battery performance by immobilized anions not only contributes to the directional construction of dendrite-free and lithium-ion permeable interface, but also brings new opportunities for the screening and design of the next generation of high-energy SSBs.