Hofmeister "Salting-In" Assisted Slurry Homogenization for Ultra-Thin Sulfide Solid-State Electrolytes

Sulfide-based all-solid-state batteries (ASSBs) demand ultra-thin electrolytes to achieve low impedance and high energy density, yet scalable fabrication remains bottlenecked by the incompatibility between binder/ solvent and sulfide solid-state electrolytes (SSEs). Here, we introduce a pioneering slurry-based strategy leveraging Hofmeister "salting-in" effect to disperse binders in a poor-solvent environment, dramatically expanding the applicable binder spectrum. The copolymer poly(vinylidenefluoride-trifluoroethylene-chlorotrifluoroethylene) (PVTC) was uniformly dispersed in tetrahydrofuran via Li-salts mediation, reducing chain aggregate to hundreds of nanometers. PVTC with reduced size was homo-dispersed in the Li₆PS₅Cl slurry, enabling the film-formation of SSE/ PVTC composite electrolytes (SCEs) with an ultra-low resistance of 0.69 Ω cm^-2, synchronously facilitating the formation of continuous polymer networks to provide mechanical cushioning that stabilizes interfaces during cycling. The high dielectric PVTC enhances Li-salts dissociation, eradicating conduction barriers and establishing efficient Li⁺-pathways. Notably, the excellent thermal transfer capability of SCEs enables direct lamination onto electrodes, enabling industrial manufacturing. ASSBs featuring LiNi_0.8Co_0.1Mn_0.1O₂ cathodes and silicon-based anodes exhibited energy densities exceeding 380 Wh kg^-1 and retained 80% capacity over 750 cycles. This work breakthrough traditional binder limitations for sulfide SSEs, addresses the transport obstruction through rational structure design, and ushers in a new era for scalable ASSB production.