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  • Sulfur–Carbon Electrode wit...
    Li, Ling; Nam, Jong Seok; Kim, Min Soo; Wang, Yifan; Jiang, Shaohua; Hou, Haoqing; Kim, Il‐Doo

    Advanced energy materials, 09/2023, Letnik: 13, Številka: 36
    Journal Article

    To address the problem of the serious capacity fading in lithium–sulfur batteries, a multi‐functional PEO(polyethylene oxide)/LiFSI (lithium bis(fluorosulfonyl)imide)/PVDF (polyvinylidene fluoride) (PLP) gel polymer electrolyte is exploited by coating PLP on a carbon nanotubes (CNTs) based sulfur cathode (PLP‐S/CNTs) with a controlled thermal annealing process. The annealing process leads to the conformal infusion of PLP through the matrix of S/CNTs with retaining the amorphous phase of the PLP, which enhance the rate performance compared to the bare S/CNTs. The PLP coating drives the transformation of more elemental sulfur to Li2S2/Li2S without forming intermediary product by restraining soluble‐polysulfides formation. Furthermore, the PLP coating successfully inhibits the dissolution of Li2Sx (x > 4) in PEO and prevents the loss of active material in the cathode, which is confirmed by density functional theory calculations. Comprehensively, the PLP coating applied to the surface of the S/CNTs cathode exhibit significantly suppressed shuttle effect and greatly improve long‐term cycle stability of the lithium–sulfur battery. The synthesized PLP‐coated S/CNTs composite cathode demonstrates a high specific capacity of 573.6 mAh g−1 at a current density of 0.5 C after 1 000 cycles, even achieving 318.1 mAh g−1 at an extremely high C‐rate (6 C). which is unprecedented performance among the reported studies on coating technology. A PEO‐LiFSI‐PVDF (PLP)‐coated S/CNTs retains high discharge capacity (573.6 mA h−1 at 0.5 C) after long‐term operation (1000 cycles) and even achieves a high discharge capacity of 318.1 mA h−1 at high rate operation of 6 C. Notably, simple coating of PLP may help bridge the gap between lab‐scale studies and industrialization of Li–S batteries.