Aqua-processable carbon quantum dot-assisted resilient polymer binder for advanced lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) with outstanding theoretical capacity and environmentally friendly properties are regarded as next-generation energy storage devices. However, the shuttle effect of lithium polysulfide (LPS) limits the practical application of LSBs. Herein, we introduce an aqua-processable carbon quantum dot (CQD)-assisted resilient waterborne polyurethane (WPU) network binder for sulfur cathodes. WPU is a well-dispersed colloidal system with abundant polar groups that is suitable for regulating LPS shuttle effects. CQDs were prepared from WPU by hydrothermal treatment. The CQDs enabled facile electron/ion transport, enhanced the adsorption capability of LPS, and formed a robust network. Moreover, the chemical similarity between WPU and CQDs enabled the formation of a well-dispersed system, thereby affording optimal electrochemical performance. The WPU-CQD binder systems exhibited stable cycling performance at a high rate of 2C, with only 0.028% retention decay per cycle over 1000 cycles.