Dual Passivation of Cathode and Anode through Electrode–Electrolyte Interface Engineering Enables Long-Lifespan Li Metal–SPAN Batteries

The reliability and durability of lithium metal (Li0)–sulfur batteries are largely limited by the undesired Li0 plating-stripping irreversibility and the detrimental polysulfide dissolution, yet approaches that can simultaneously address the above anodic and cathodic problems are scarce. Herein, we report the stable operation of a Li0-SPAN (sulfurized polyacrylonitrile) battery via an anode–cathode dual-passivation approach. By combination of a fluorinated localized high concentration electrolyte (LHCE) and a Li3N-forming additive (TMS-N3), robust and highly conductive electrode passivation layers are formed in situ on the surface of both the Li0 anode and the SPAN cathode. The resulting highly reversible, dendrite-free, and high-density Li0 plating morphology enables a high Coulombic efficiency of 99.4%. Advanced tender energy X-ray spectroscopy also reveals the eliminated Li2S formation and minimized polysulfide dissolution in SPAN cathodes, leading to a high capacity of 580 mAh/gSPAN and stable cycling with negligible capacity decay (0.7%) for 800 cycles. This electrode–electrolyte interphase engineering strategy has tackled the major limitations of Li–S batteries in both ether- and carbonate-based electrolyte systems and under a wide temperature range from −10 to +50 °C, thus providing insightful guidelines for the rational design of highly durable and high-energy-density Li0-S batteries.