Multi‐Faceted Binder Enhancement via Slurry‐Applicable Thiol‐Ene Click Chemistry for Low‐Pressure‐Operable All‐Solid‐State Batteries

Abstract Ensuring low‐pressure operability is imperative in the practical deployment of all‐solid‐state batteries (ASSBs) with sulfide solid electrolytes, highlighting the pivotal roles of functional binders. Herein, slurry‐applicable thiol‐ene click reaction‐derived modifications of styrene‐butadiene rubber (SBR) binders are introduced to enhance the electrochemo‐mechanical stabilities of composite cathodes under low operating pressures. Two key modifications are realized: the grafting of carboxylate functional groups to improve the adhesion and cross‐linking to enhance the modulus and elasticity. A key insight gained is that cross‐linking is considerably more critical in improving the low‐pressure performance than adhesion enhancement. Electrochemical evaluations using single‐crystalline LiNi 0.8 Co 0.1 Mn 0.1 O 2 |Li 6 PS 5 Cl|(Li‐In) half‐cells at 0.3 MPa indicate that LiNi 0.8 Co 0.1 Mn 0.1 O 2 electrodes with the cross‐linked binder exhibit superior electrochemical performances, including higher initial discharge capacities and improved initial Coulombic efficiencies and capacity retentions compared to those of the unmodified‐SBR‐based electrodes (163 vs. 133 mA h g −1 , 68% vs. 73%, and 67% vs. 75% at the 100th cycle, respectively). Comprehensive analyses, including operando electrochemical pressiometry, reveal that cross‐linking effectively maintains the electrode integrity, thereby stabilizing the interfacial resistance during cycling. These findings offer critical design guidelines for practical, high‐performance ASSB systems.