Electrolyte Lubricants for Solid-State Batteries.

Abstract

Solid-state batteries (SSBs) promise higher energy density and improved safety, but interparticle voids and unstable solid-solid interfaces still limit their performance. Here, we translate the concept of lubrication into an electrolyte-lubrication strategy for SSBs. We design a solvation-tailored electrolyte lubricant, termed ACE (aggregate cluster electrolyte), in which spatially structured ion-pair clusters direct interphase formation. In ACE, molecular-orbital reconfiguration within Li+-anion clusters favors the growth of a thin, electronically insulating, inorganic-rich solid-liquid electrolyte interphase (SLEI) on sulfide electrolytes, mitigating their intrinsic instability. The fluid ACE infiltrates interparticle voids, forming percolating Li+-conduction networks and facilitating dynamic reconstruction of the solid-electrolyte interphase during cycling. These attributes enable stable Li-metal cycling at reduced external pressure and enhance cathode active-material utilization. Electrochemical-thermal simulations further show that ACE homogenizes ionic fluxes and thermal gradients at the cell scale. Electrolyte lubrication thus emerges as a scalable interfacial-engineering approach for making sulfide-based SSBs operate under more practical conditions.