An artificial cathode-electrolyte interphase enabling one-step sulfur transition in polyethylene oxide-based solid-state lithium-sulfur batteries

All-solid-state lithium-sulfur (Li-S) batteries using polyethylene oxide (PEO)-based electrolytes hold the advantages of high theoretical energy density, cost-effectiveness, and high safety. However, the drawback of polysulfide dissolution in PEO results in a short battery lifespan. Here, we propose to construct an artificial cathode-electrolyte interphase (CEI) on the S cathode, which converts the S speciation pathway to a one-step solid transition, significantly mitigating the polysulfide migration in PEO. Surface analyses and theoretical calculations reveal the composition of the CEI and its effect on the reaction mechanism. As a result, the all-solid-state Li-S cell with the artificial CEI is able to deliver 873 mA h g⁻¹ at 100 mA g⁻¹ and maintain 739 mA h g⁻¹ after 50 cycles, whereas the cell using the pristine S cathode retains only 364 mA h g⁻¹. More remarkably, the artificial CEI enables the cell to achieve a high capacity retention rate of 83.1% at 300 mA g⁻¹ over 200 cycles, demonstrating that our strategy of CEI manipulation effectively enhances the cycling reversibility of PEO-based solid-state Li-S batteries.