Regulating Polysulfide Redox Kinetics on a Self‐Healing Electrode for High‐Performance Flexible Lithium‐Sulfur Batteries

• DOI: 10.1002/adfm.202110313
• Publication Date: 2021-12-29T08:39:16Z
• Authors: Runhua Gao; Qi Zhang; Yun Zhao; Zhiyuan Han; Chongbo Sun; Jinzhi Sheng; Xiongwei Zhong; Biao Chen; Chuang Li; Shuyan Ni; Zhihong Piao; Baohua Li; Guangmin Zhou
• Keywords: Polysulfide; Gravimetric analysis

Abstract Wearable electronics require lightweight and flexible batteries, of which lithium‐sulfur (Li‐S) batteries are great interest due to their high gravimetric energy density. Nevertheless, Li‐S have unsatisfactory electrochemical performance owing electrode fracture during repeated bending, the volume change sulfur species severe shuttle effect. Binders play essential roles in these but always lacked attention. Herein, a self‐healing polyvinylpyrrolidone‐polyethyleneimine (PVP‐PEI) binder cross‐linked by hydrogen bonds, also regulates polysulfide redox kinetics, is reported. The dynamic hydrogen‐bonding networks repair cracks ensure integrity while numerous polar groups such as CO ‐NH 2 suppress effect immobilizing polysulfides. Therefore, with PVP‐PEI exhibit excellent cycling stability (a capacity decay rate 0.0718% per cycle at 1 C after 450 cycles), an outstanding areal 7.67 mAh cm −2 even under loading (7.1 mg ) relatively lean electrolyte conditions ( E / S ratio = 8 µL −1 ). Flexible pouch cells using show stable for 140 cycles favorable retention over 95% 2800 bending cycles, confirming its application potential high‐performance batteries.