Although lithium–sulfur (Li–S) batteries have attracted strong consideration regarding their fundamental mechanism and energy applications, the inferior cycling performance and low reaction rate caused by the “shuttling effect” and the sluggish reaction kinetics of lithium polysulfides (LiPSs) impede their practical application. In this work, graphitic C₃N₄ (g-C₃N₄) assembled with highly-dispersed nitrogen-containing carbon quantum dots (CQDs) is designed as a cooperative catalyst to accelerate the reaction kinetics of LiPS conversion, the precipitation of Li₂S during discharging, and insoluble Li₂S decomposition during the charging process. Meanwhile, the introduction of CQDs improves the conductivity of the g-C₃N₄ substrate, showing great significance for the construction of high-performance electrocatalysts. As a result, the as-obtained composite shows efficient adsorption and electrochemical conversion of LiPSs, and the Li–S batteries assembled with CQDs/g-C₃N₄ exhibit an initial specific capacity of 1300.0 mA h g⁻¹ at the current density of 0.1C and retain 582.3 mA h g⁻¹ after 200 cycles. The electrode with the modified composite displays a greater capacity contribution of Li₂S precipitation (175.7 mA h g⁻¹), indicating an enhanced catalytic activity of g-C₃N₄ decorated by CQDs. The rational design of CQDs/g-C₃N₄ as a sulfur host could be an effective strategy for developing high performance Li–S batteries.

中文翻译：

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碳量子点修饰的 g-C3N4 复合材料作为锂硫电池的硫主体材料

尽管锂硫（Li-S）电池在其基本机制和能源应用方面引起了人们的广泛关注，但由于“穿梭效应”和缓慢的反应动力学导致的较差的循环性能和低反应速率，阻碍了其在多硫化锂（LiPS）中的应用。实际应用。在这项工作中，石墨C ₃ N ₄ (gC ₃ N ₄ )与高度分散的含氮碳量子点(CQD)组装在一起被设计为协同催化剂，以加速LiPS转化、Li ₂ S沉淀的反应动力学。放电过程中不溶性Li 2 S分解，充电过程中不溶性Li _{2 S分解。同时，CQDs的引入提高了gC 3} N ₄基底的电导率，对于构建高性能电催化剂具有重要意义。结果，所获得的复合材料表现出LiPSs的高效吸附和电化学转化，并且用CQDs/gC ₃ N ₄组装的Li-S电池在0.1C的电流密度下表现出1300.0 mA hg ^-1的初始比容量并在200次循环后保留582.3 mA hg ^-1。具有改性复合材料的电极表现出更大的Li ₂ S沉淀容量贡献(175.7 mA hg ^-1 )，表明CQD装饰的gC ₃ N ₄的催化活性增强。合理设计CQDs/gC ₃ N ₄作为硫主体可能是开发高性能Li-S电池的有效策略。