High-performance shuttle-free quasi-solid-state room temperature Na-S batteries using a high sulfur-loaded organosulfur cathode

Room-temperature sodium-sulfur (RT-Na/S) battery technology is a promising alternative to conventional batteries. Unlike high-temperature Na-S batteries, RT-Na/S batteries are safer and cheaper but have limitations such as polysulfide dissolution and low energy density, which hinder their industrial development. Herein, sulfurized poly(vinylpyridine) (SPVP) was used for the first time as an efficient cathode material in RT-Na/S batteries. SPVP, synthesized by a scalable one-step method, contains 60 wt% covalently bound sulfur in the form of short-chain polysulfides, which, together with a gel electrolyte, synergistically surpass polysulfide dissolution and hence eliminate the shuttle effect. The quasi-solid-state Na-S cells achieve a high capacity of 900 mAh g s −1 (535.5 mAh g −1 @total active materials and 247.2 mAh g −1 @total cathode) with 80% capacity retention after 200 cycles. The covalently bound sulfur and the porous polymeric structure in SPVP materials enable high charge storage and stable cycling in RT-Na/S systems. Further, post-mortem analysis revealed that the electrodes retain their structural integrity and robustness during cycling, thereby avoiding degradation.