A crosslinking hydrogel binder for high-sulfur content S@pPAN cathode in rechargeable lithium batteries

High-energy density lithium-sulfur (Li-S) batteries have received intensive attention as promising energy storage system. Among diverse sulfur-based cathodes, sulfurized pyrolyzed poly(acrylonitrile) (S@pPAN) cathode delivered superior electrochemical performance. However, the sulfur content of S@pPAN is relatively low (<50 wt%), which significantly limits the energy density. Herein, a hydrogel SA-Cu binder was proposed with a crosslinking network constructed by Cu 2+ ions. The introduction of Cu 2+ ions enabled excellent electrochemical behaviors of S@pPAN cathode even with high sulfur content of 52.6 wt% via chemical interaction with sulfur and polysulfide. Moreover, a favorable cathode interphase was formed containing electrochemically active and conductive CuS x . S@pPAN/SA-Cu exhibited a high sulfur utilization of 85.3%, long cycling stability over 1000 cycles and remarkable capacity of 1200 mAh g s −1 even at 10 C. Furthermore, ascribed to the improved electrode structure, high-loading electrode (sulfur loading: 4 mg cm −2 ) displayed stable cycling with areal capacity of 5.26 mAh cm −2 (1315 mAh g s −1 ) after 40 cycles. This study provides new directions to prepare high-sulfur content and high-loading S@pPAN cathode for higher energy density.