Elastic Binder for High-Performance Sulfide-Based All-Solid-State Batteries

Sulfide-based all-solid-state batteries (ASSBs) offer en-hanced safety and potentially high energy density. Particularly, an"anode-less"electrode containing metallic seeds that form a solid-solution with lithium was recently introduced to improve the cycle life ofsulfide-based ASSB cells. However, this anode-less electrode is graduallydestabilized because the metal particles undergo severe volumeexpansion during repeated cycling. Furthermore, the irreversibility ofthe electrode in early cycles impairs the energy density of the cellsignificantly. Herein, we introduce an elastic polymer known as"Spandex"as a binder for the silver-carbon composite. The soft andhard segments of this binder act synergistically in that the former engagesin strong hydrogen bonding with the active material and the latterpromotes elastic adjustment of the binder network. This binder designsignificantly improves the charge-discharge reversibility and long-termcyclability of the anode-less ASSB cell and provides insights into elastic binder systems for high-capacity ASSB anodes thatundergo a large volume expansion.