Lithium–sulfur batteries (LSBs) hold significant potential for energy storage but are hindered by challenges such as the shuttle effect and the slow conversion of soluble lithium polysulfides (LiPSs). In this study, we proposed a robust strategy of constructing redox-active metal–organic framework mediators (RM-MOFs) for use as sulfur hosts and effective redox mediators (RMs) in LSBs. The RM-MOF immobilizes the redox-active dithiothreitol (DTT) molecules on the exposed metal sites of the mesoporous MOF, which can prevent the loss of DTT, arrange it uniformly in separate pores, confine LiPSs, and continuously modulate redox kinetics during long-term cycling. Notably, the RM-MOF streamlines the redox pathways through redox reactions between LiPSs and the –SH groups of the DTT units, forming short-chain organosulfur compounds and facilitating radical reactions. Leveraging these advantages, the RM-MOF significantly enhances the performance of LSBs in both discharge capacity at various C-rates and cycling stability (over 90% reduced decay rate), enabling a high areal capacity of 13.8 mA h cm⁻² at high sulfur loading and high-energy density (316.5 W h kg⁻¹) pouch cell operation. Importantly, this work provides insight into the design and functional mechanisms of the RM-MOF, paving the way for the development of more advanced porous mediators for next-generation LSBs.

中文翻译：

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氧化还原活性金属有机框架介质可在锂硫电池中增强多硫化物限制并简化反应途径


锂硫电池 （LSB） 在储能方面具有巨大的潜力，但受到穿梭效应和可溶性多硫化锂 （LiP） 缓慢转化等挑战的阻碍。在这项研究中，我们提出了一种构建氧化还原活性金属有机框架介质 （RM-MOF） 的稳健策略，用作 LSB 中的硫宿主和有效氧化还原介质 （RM）。RM-MOF 将氧化还原活性二硫苏糖醇 （DTT） 分子固定在介孔 MOF 的裸露金属位点上，可以防止 DTT 的损失，将其均匀排列在单独的孔中，限制 LiPSs，并在长期循环过程中持续调节氧化还原动力学。值得注意的是，RM-MOF 通过 LiPSs 与 DTT 单元的 −SH 基团之间的氧化还原反应简化了氧化还原途径，形成短链有机硫化合物并促进自由基反应。利用这些优势，RM-MOF 显着提高了 LSB 在各种 C 速率下的放电容量和循环稳定性（衰减率降低 90% 以上）的性能，在高硫负载和高能量密度 （316.5 Wh kg⁻1） 软包电池操作下实现了 13.8 mAh cm⁻2 的高面容量。重要的是，这项工作提供了对 RM-MOF 设计和功能机制的见解，为开发更先进的多孔介质铺平了道路，用于下一代 LSB。