Constructing lithium oxysulfide-rich solid electrolyte interphase to shield polysulfides in practical lithium–sulfur batteries

Long-cycling practical lithium–sulfur batteries are hindered by the parasitic reactions between lithium polysulfide (LiPS) intermediates and lithium metal anodes. Solid electrolyte interphase (SEI) on lithium metal anodes plays a crucial role in shielding the parasitic reactions of LiPSs. Herein, a lithium oxysulfide-rich SEI is demonstrated to shield polysulfides for stabilizing lithium metal anodes in working lithium–sulfur batteries. Li2SO4 is sustainably released as an additive to introduce abundant lithium oxysulfide components, such as sulfates, sulfites, and other Li2SxOy in SEI. The lithium oxysulfide-rich SEI effectively shields the parasitic reactions of LiPSs and the lifespan of lithium–sulfur batteries increases by 60% under demanding conditions of ultrathin Li anodes (50 μm) and high-loading S cathodes (4.0 mg cm−2). Furthermore, a practical 2.59 Ah lithium–sulfur pouch cell with the lithium oxysulfide-rich SEI delivers 25 cycles with an initial specific energy of 352 Wh kg−1. This work provokes insights into the role of lithium oxysulfide in SEI and inspires rational regulation of SEI to stabilize lithium–sulfur batteries.