High-valence sulfur-containing species in solid electrolyte interphase stabilizes lithium metal anodes in lithium–sulfur batteries

The interfacial stability of lithium metal anodes dictated by solid electrolyte interphase (SEI) is essential for long-cycling high-energy-density lithium–sulfur batteries. Nevertheless, critical components of SEI for interfacial stabilization are particularly indistinct. Herein, the effect of various sulfur-containing components in SEI for stabilizing lithium metal anodes is disclosed in lithium–sulfur batteries. High-valence sulfur-containing species (Li₂SO₃ and Li₂SO₄) in SEI are conducive to uniform lithium deposition and stabilizing lithium metal anodes. In contrast, low-valence sulfur-containing species (Li₂S and Li₂S₂) in SEI result in aggressive lithium dendrites and dead lithium. This work identifies the role of sulfur-containing components in SEI for stabilizing lithium metal anodes and provides rational design principles of SEI for protecting lithium metal anodes in practical lithium–sulfur batteries.