Activating Interfacial Ion Exchange in Composite Electrolytes to Realize High-Rate and Long-Cycling Solid-State Lithium Batteries.

Composite solid electrolytes (CSEs) are promising candidates for solid-state lithium metal batteries. However, the poor cross-phase Li transport restricts the rate performance and cycle life of the batteries. Herein, we revealed the Li percolation behavior in poly(vinylidene fluoride) (PVDF)-based CSEs with LiLaZrTaO filler. The de-coordination barrier from Li clusters determines interfacial Li transport capability. We then employed a designed N-methyl-2,2,2-trifluoroacetamide (NMTFA) ligand to lower the de-coordination energy and activate interfacial Li exchange. The ionic conductivity is therefore increased from 3.32 × 10 to 7.30 × 10 S cm. By tracking the Li and Li substitution process, it was identified that the proportion of interfacial Li transport increases from 11% to 26%. The NMTFA also contributes to the formation of inorganic-rich interphases with electrodes. As a result, the Li||LiNiCoMnO solid-state batteries exhibit ultra-long lifespans of 2400, 3000, and 10 000 times at 2, 5, and 10C, respectively, as well as achieve 1000 cycles at 50 °C and 300 cycles at -30 °C. This work highlights the critical role of interfacial Li transport for the CSEs with "polymer-Li clusters-filler" configuration to realize high-rate and long-cycling solid-state lithium batteries.