Mitigating Chemo-Mechanical Failure in Li-S Solid State Batteries with Compliant Cathodes

Solid-state sulfur cathodes based on inorganic sulfide solid electrolytes can enable energy-dense lithium batteries. However, volume changes and chemical decomposition can drive delamination and degradation during cycling. To overcome these challenges, this paper reports an in situ approach to encapsulate the solid-state sulfur cathode with a gel polymer electrolyte (GPE). The GPE is covalently bonded with the sulfide solid electrolyte and acts as a barrier that suppresses chemical decomposition between the sulfide solid electrolyte and cathode active material. The elastic GPE maintains interfacial contact within the sulfur cathode allowing for greater sulfur utilization. The solid-state sulfur cathode with GPE demonstrates capacities nearing 700 mAh g⁻¹ and capacity retention over 100 cycles.