Long‐Life Sulfide All‐Solid‐State Battery Enabled by Substrate‐Modulated Dry‐Process Binder

Abstract Sulfide all‐solid‐state batteries (ASSBs) have been widely acknowledged as next‐generation energy‐storage devices due to their improved safety performance and potentially high energy density. Among the various fabrication methods of sulfide ASSBs, solvent‐free dry‐film processes have unique advantages including reduced costs, suppressed film delamination, thick electrodes, and high compatibility with sulfide solid electrolytes (SEs). However, the currently dominating binder for dry‐film process polytetrafluoroethylene suffers from poor voltage stability and low viscosity, which leads to low Coulombic efficiency and poor cycling stability of sulfide ASSBs. Herein, a specially‐designed treatment is developed to obtain a new type of dry binder, styrene‐butadiene rubber (SBR), exploiting paraxylene and a NaCl substrate to dissolve and re‐precipitate SBR for controlling its stacking state, micro‐structure/morphology, density, and dispersion performance. The SE membrane prepared using this processed SBR exhibits ultra‐high ionic conductivity (2.34 mS cm ‐1 ), contributing to excellent cycle stability of the corresponding sulfide ASSB (>84% capacity retention after 600 cycles at 0.3C).