A Self‐Healable Sulfide/Polymer Composite Electrolyte for Long‐Life, Low‐Lithium‐Excess Lithium‐Metal Batteries

Abstract Solid electrolyte‐protected lithium‐metal anodes promise energy‐dense, safe cells. While sulfide solid electrolytes enable facile processability and fast ion transport, they suffer from complex chemo‐mechanical issues, including Li plating‐induced fracture and Li stripping‐induced contact loss. To address these issues, a grafting approach is implemented to functionalize the sulfide solid electrolyte (Li 3,85 Sn 0.85 Sb 0.15 S 4 ) with a self‐healing unit. This leads to a dynamic bonding between the solid electrolyte network and a mechanically robust polymer scaffold, which reversibly accommodates the volume changes of the lithium‐metal anode. Moreover, the approach improves the interfacial contact between the lithium‐metal anode and the composite electrolyte, enabling stable cycling at a mild stack pressure (160 kPa). With a negative to positive capacity ratio equals to 1, pouch full cells with a high‐nickel cathode (nickel content > 90%) and lithium‐metal anode display 92% capacity retention for 140 cycles. Engineering the interface between solid electrolyte and the polymeric binder offers a promising pathway to address the chemo‐mechanical issues.