Yang Xiao-Xia, Li Xu-Ting, Zhao Chang-Feng, Fu Zhang-Hua, Zhang Qing-Shuai, Hu Cheng
Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), School of Materials Science and Engineering, Shandong University, Ji'nan 250061, Shandong, China.
ACS Appl Mater Interfaces. 2020 Jul 22;12(29):32752-32763. doi: 10.1021/acsami.0c08027. Epub 2020 Jul 13.
The sulfur redox in Li-S batteries involves a complex sequence of solid-liquid-solid conversions, and reaction catalysis has recently become a focused area for further advancement. The deposition of solid LiS from liquid LiS contributes to three-quarters of the total theoretical capacity and is therefore of great significance over the entire cathode reaction. This study demonstrates a cathode material composed of carbon nanofibers decorated with catalytic Co phthalocyanine nanorods (CoPc@CNF), which are highly effective in promoting the deposition of LiS in three-dimensional (3D) fine particles rather than 2D thin films. This significantly alleviates cathode passivation during cell charge and discharge, leading to obviously improved sulfur utilization and cycling stability for high loading cathodes. DFT calculations indicate that the promoted 3D deposition of LiS is related to the facilitated migration of deposition precursors (LiS and Li-ions) to migrate on the CoPc nanorods. Lithium-sulfur (Li-S) pouch cells were prepared with high specific (954 mAh g), areal (4.8 mAh cm), and total (235 mAh) capacities achieved at 0.5 C under high sulfur content. As metal phthalocyanines possess a high structural variability, this study provides opportunities to the design of a new class of Li-S cathode materials.
锂硫电池中的硫氧化还原涉及一系列复杂的固-液-固转化过程，反应催化最近已成为进一步发展的重点领域。从液态硫化锂中沉积固态硫化锂占理论总容量的四分之三，因此在整个阴极反应中具有重要意义。本研究展示了一种由碳纳米纤维组成的阴极材料，其表面装饰有催化酞菁钴纳米棒（CoPc@CNF），这种材料在促进硫化锂以三维（3D）细颗粒而非二维薄膜形式沉积方面非常有效。这显著减轻了电池充放电过程中的阴极钝化，从而显著提高了高负载阴极的硫利用率和循环稳定性。密度泛函理论（DFT）计算表明，促进硫化锂的三维沉积与沉积前驱体（硫化锂和锂离子）在酞菁钴纳米棒上更容易迁移有关。制备了锂硫（Li-S）软包电池，在高硫含量下，于0.5 C时实现了高比容量（954 mAh g）、面积容量（4.8 mAh cm）和总容量（235 mAh）。由于金属酞菁具有高度的结构可变性，本研究为设计新型锂硫阴极材料提供了机会。
