Polymeric Materials for Scalable, Reliable Sulfide-Based All-Solid-State Batteries

Sulfide-based all-solid-state batteries (ASSBs) are considered to be a next-generation energy storage concept that offers enhanced safety and potentially high energy density. Despite considerable progress in the development of materials, sulfide-based ASSB technology still remains at research stage without solution-based scalable manufacturing schemes having been established because of the incompatible polarity of binder, solvent, and sulfide electrolyte during slurry preparation. In this talk, I will introduce a novel binder design based on protection-deprotection chemistry, which resolves the tricky issue of polarity compatibility among the three electrode components (solvent, binder, and SE) in the slurry solution. Protection by the tert-butyl group allows for homogeneous dispersion of the binder in the slurry based on a relatively less polar solvent, with subsequent heat-treatment during the drying process to cleave the tert-butyl group. Upon deprotection, the polar carboxylic acid group is exposed, which enables hydrogen bonding interaction with the high-nickel layered oxide active material. Deprotection strengthens the electrode adhesion drastically, even beyond the levels of commercial LIB electrodes, and the key electrochemical performance parameters are improved markedly in both half-cell and full-cell settings. This study highlights the potential of sulfide-based ASSBs for scalable manufacturing and also provides insights that protection-deprotection chemistry could generally be used for various battery cells that suffer from polarity incompatibility among multiple electrode components.