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Wearable electronics require lightweight and flexible batteries, of which lithium‐sulfur (Li‐S) batteries are of great interest due to their high gravimetric energy density. Nevertheless, flexible Li‐S batteries have unsatisfactory electrochemical performance owing to electrode fracture during repeated bending, the volume change of sulfur species and the severe shuttle effect. Binders play essential roles in these batteries but have always lacked attention. Herein, a self‐healing polyvinylpyrrolidone‐polyethyleneimine (PVP‐PEI) binder cross‐linked by hydrogen bonds, which also regulates polysulfide redox kinetics, is reported. The dynamic hydrogen‐bonding networks repair the cracks and ensure the integrity of the electrode while numerous polar groups such as CO and ‐NH2 suppress the shuttle effect by immobilizing polysulfides. Therefore, Li‐S batteries with the PVP‐PEI binder exhibit excellent cycling stability (a capacity decay rate of 0.0718% per cycle at 1 C after 450 cycles), an outstanding areal capacity of 7.67 mAh cm−2 even under a high sulfur loading (7.1 mg cm−2) and relatively lean electrolyte conditions (E/S ratio = 8 µL mg−1). Flexible Li‐S pouch cells using the PVP‐PEI binder show a stable performance for 140 cycles and a favorable capacity retention of over 95% after 2800 bending cycles, confirming its application potential in high‐performance flexible Li‐S batteries. [ABSTRACT FROM AUTHOR]

Abstract: Due to high energy density, low cost, and nontoxicity, lithium–sulfur (Li–S) batteries are considered as the most promising candidate to satisfy the requirement from the accelerated development of electric vehicles. However, Li–S batteries are subjected to lithium polysulfides (LiPSs) shuttling due to their high dissolution in liquid electrolyte, resulting in low columbic efficiency and poor cycling performance. Moreover, the Li metal as an indispensable anode of Li–S batteries shows serious safety issues derived from the lithium dendrite formation. The replacement of liquid electrolytes with solid‐state electrolytes (SSEs) has been recognized as a fundamental approach to effectively address above problems. In this review, the progress on applying various classes of SSEs including gel, solid‐state polymer, ceramic, and composite electrolytes to solve the issues of Li–S batteries is summarized. The specific capacity of Li–S batteries is effectively improved due to the suppression of LiPSs shuttling by SSEs, while the rate and cycling performance remain relatively poor owing to the limited ionic conductivity and high interfacial resistance. Designing smart electrode/electrolyte integrated architectures, enabling the high ionic transportation pathway and compatible electrode/electrolyte interface, may be an effective way to achieve high performance solid‐state Li–S batteries. [ABSTRACT FROM AUTHOR]