Selenium-Doped\nSulfurized Polyacrylonitrile Hybrid\nCathodes with Ultrahigh Sulfur Content for High-Performance Solid-State\nLithium Sulfur Batteries

Abstract

The solid-state lithium sulfur battery (SSLSB) is an\nattractive\nnext-generation energy storage system by reason of its remarkably\nhigh energy density and safety. However, the SSLSB still faces critical\nchallenges, such as sluggish reaction kinetics, mismatched interface,\nand undesirable reversible capacity. Herein, a high-performance SSLSB\nis reported using sulfurized polyacrylonitrile with rich selenium-doped\nsulfur (Se/S–S@pPAN) as a cathode and poly(ethylene oxide)/Li₇La₃Zr_1.4Ta_0.6O₁₂ (PEO-LLZTO) as an electrolyte. The sulfur content of the cathode\nup to 60.9 wt % can be achieved by dispersing selenium sulfide (SeS_<i>x</i>) species in the sulfurized polyacrylonitrile\n(S@pPAN) skeleton at a molecular level. Selenium as a eutectic accelerator\ncan be uniformly distributed in the composite through the Se–S\nbond and can accelerate the reaction kinetics. The PEO-LLZTO hybrid\nsolid-state electrolyte (SSE) displays an attractive electrochemical\nperformance and provides an intimate contact with electrodes. At 60\n°C, Se/S–S@pPAN delivers an impressive discharge capacity\nof 1042 mAh g^–1 at 0.1C and 445 mAh g^–1 at 1C. Additionally, the LiFePO₄ cathodes combined with\nPEO-LLZTO deliver a high reversible capacity (158.9 mAh g^–1, 1C) and an ultralong lifespan (a capacity retention of 80%, 1000\ncycles) at 1C. The synergetic design of the high-performance sulfur\ncathode and the organic/inorganic hybrid electrolyte is crucial for\nenabling the high-performance SSLSB.