Thiol–Ene Click Reaction for Fine Polarity Tuning of Polymeric Binders in Solution-Processed All-Solid-State Batteries

Recent studies of all-solid-state batteries (ASSBs) have identified sulfide-based electrolytes with comparable ionic conductivities as those of liquid counterparts. Nevertheless, solution-based manufacturing is unestablished, since it is challenging to find adhesive polymeric binders that can be dispersed in common solvents with sulfide electrolytes. Currently available binders exhibit insufficient electrode adhesion due to their low polarity and are compromised by the chemical stability of a slurry. Here, we report a thiol-ene click reaction used to graft styrene-butadiene-block-copolymer with carboxylic acid at an optimal concentration. With polarity tuning, the click binder results in a uniform electrode slurry without ruining the structure of the sulfide electrolytes, while enabling electrode adhesion 1.4 times as high as that of commercial lithium-ion battery electrodes. The click binder also allows ASSBs to deliver decent electrochemical performance, implying that fine polarity tuning of functional binders can constitute an important step forward in advancing ASSBs to a real scalable technology.