Unraveling the catalytic redox mechanism of lithium-sulfur batteries through advanced in-situ/operando characterizations

Accelerating the redox conversion of lithium polysulfides (LiPSs) with electrocatalysts has been regarded as an effective avenue to surmount the shuttle effect and realize high-performance lithium-sulfur (Li-S) batteries. However, the complicated reaction process, especially the real-time evolution of sulfur-containing species and electrocatalysts under working conditions, has brought great difficulties in the explicit understanding of reaction mechanism of Li-S batteries, thereby severely hampering the design of highly efficient electrocatalysts. Therefore, a crucial prerequisite for correctly identifying the reaction mechanism is an in-depth analysis of the dynamic evolution of reaction intermediates and their structure-performance relationships. In this review, we comprehensively summarized the most recent progress in the dynamic behaviors of LiPSs and electrocatalysts of Li-S batteries under working conditions in conjunction with closely related in-situ/operando characterizations to recognize the realtime evolution of phase, composition, and atomic/electronic structure, thereby unraveling the corresponding catalytic mechanism. In addition, the major challenges and unexplored issues of catalytic conversion of LiPSs were summarized and discussed, aiming to provide perspectives into the development of highly efficient electrocatalysts in Li-S chemistry. Based on this review, we believe that reasonable regulation of reconstruction behaviors can achieve satisfactory electrocatalysts with high catalytic activity, accelerating the development of green energy.