State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
National Laboratory of Solid State Microstructures and College of Engineering and Applied Sciences, Nanjing University, Jiangsu 210093, China.
ACS Nano. 2023 Feb 14;17(3):3143-3152. doi: 10.1021/acsnano.2c12436. Epub 2023 Jan 30.
The slow conversion and rapid shuttling of polysulfides remain major challenges that hinder the practical application of lithium-sulfur (Li-S) batteries. Efficient catalysts are needed to accelerate the conversion and suppress the shuttling. However, the lack of a rational understanding of catalysis poses obstacles to the design of catalysts, thereby limiting the rapid development of Li-S batteries. Herein, we theoretically analyze the modulation of the electronic structure of CoPS caused by the NiAs-to-MnP-type transition and its influence on catalytic activity. We found that the interacting d-orbitals of the active metal sites play a determining role in adsorption and catalysis, and the optimal d-, d-, and d-orbitals in an appropriately distorted five-coordinate pyramid enable higher catalytic activity compared with their parent structures. Finally, rationally designed catalysts and S were electrospun into carbonized nanofibers to form nanoreactor chains for use as cathodes. The resultant Li-S batteries exhibited superior properties over 1000 cycles with only a decay rate of 0.031% per cycle and demonstrated a high capacity of 887.4 mAh g at a high S loading of 10 mg cm. The structural modulation and bonding analyses in this study provide a powerful approach for the rational design of Li-S catalysts.
多硫化物的缓慢转化和快速穿梭仍然是阻碍锂硫（Li-S）电池实际应用的主要挑战。需要高效的催化剂来加速转化并抑制穿梭。然而，对催化作用缺乏合理的理解阻碍了催化剂的设计，从而限制了 Li-S 电池的快速发展。在此，我们从理论上分析了 NiAs 到 MnP 型转变引起的 CoPS 电子结构的调制及其对催化活性的影响。我们发现，活性金属位点的相互作用 d 轨道在吸附和催化中起着决定性的作用，在适当扭曲的五配位金字塔中，最佳的 d、d 和 d 轨道可以比其母体结构具有更高的催化活性。最后，合理设计的催化剂和 S 被电纺成碳化纳米纤维，形成纳米反应器链作为阴极。所得 Li-S 电池在 1000 次循环后表现出优异的性能，循环衰减率仅为 0.031%/循环，在高 S 负载量为 10 mg cm 时表现出 887.4 mAh g 的高容量。本研究中的结构调制和键合分析为 Li-S 催化剂的合理设计提供了一种强大的方法。
