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.