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

Sulfide-based all-solid-state batteries (ASSBs) offer enhanced 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 of sulfide-based ASSB cells. However, this anode-less electrode is gradually destabilized because the metal particles undergo severe volume expansion during repeated cycling. Furthermore, the irreversibility of the electrode in early cycles impairs the energy density of the cell significantly. Herein, we introduce an elastic polymer known as "Spandex" as a binder for the silver–carbon composite. The soft and hard segments of this binder act synergistically in that the former engages in strong hydrogen bonding with the active material and the latter promotes elastic adjustment of the binder network. This binder design significantly improves the charge–discharge reversibility and long-term cyclability of the anode-less ASSB cell and provides insights into elastic binder systems for high-capacity ASSB anodes that undergo a large volume expansion.