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 Cu2+ ions. The introduction of Cu2+ 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 CuSx. 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: 4mg 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. (C) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press.

Automated summary

A novel hydrogel SA-Cu binder with Cu2+ ions was proposed to enhance the electrochemical performance of high-sulfur content S@pPAN cathode, achieving a high sulfur utilization, stable cycling performance, and remarkable capacity. The introduction of Cu2+ ions enabled the formation of an ideal cathode interphase containing electrochemically active and conductive CuSx, leading to improved electrode structure and cycling stability. This study provides new directions for the preparation of high-sulfur content and high-loading S@pPAN cathode for higher energy density.