Meng Xueping, Li Zhonglin, Cheng Zhibin, Li Pengyue, Wang Ruihu, Li Xiaoju
Fujian Provincial Key Laboratory of Polymer Materials, College of Chemistry and Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, China.
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China and Tianjin Key Laboratory of Chemical Process Safety, School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China.
Nanoscale. 2021 Mar 18;13(10):5292-5299. doi: 10.1039/d1nr00176k.
Transition metal nitrides are promising mediators for improving the electrochemical performance of lithium-sulfur (Li-S) batteries, but the synthesis of ultrafine and durable nanoparticles in the absence of ammonia gas is still a great challenge. Herein, we reported a new method for the fabrication of ultrafine vanadium nitride (VN) nanoparticles uniformly embedded into N-doped porous carbon using a main-chain imidazolium-based ionic polymer (ImIP) containing metavanadate anions as a precursor. ImIP not only serves as sole carbon and nitrogen sources, but also effectively inhibits the aggregation and coalescence of VN nanoparticles during pyrolysis. Benefiting from the ultrafine particle size, high polarity and good electrocatalytic effects of VN, both redox kinetics of sulfur species and chemical adsorbability toward polysulfides are greatly expedited. The resultant electrode exhibits superior cycling stability with a low average capacity decay rate of 0.035% for 1200 cycles at a high rate of 5 C. This work develops a facile ammonia-free approach to fabricate ultrafine VN nanoparticles for improving electrochemical behaviors of Li-S batteries.
过渡金属氮化物有望成为改善锂硫（Li-S）电池电化学性能的介质，但在无氨气条件下合成超细且耐用的纳米颗粒仍是一项巨大挑战。在此，我们报道了一种新方法，以含有偏钒酸根阴离子的主链咪唑鎓基离子聚合物（ImIP）为前驱体，制备均匀嵌入氮掺杂多孔碳中的超细氮化钒（VN）纳米颗粒。ImIP不仅作为唯一的碳源和氮源，还能有效抑制热解过程中VN纳米颗粒的聚集和合并。受益于VN的超细粒径、高极性和良好的电催化作用，硫物种的氧化还原动力学以及对多硫化物的化学吸附性均得到极大加快。所得电极表现出优异的循环稳定性，在5 C的高倍率下1200次循环的平均容量衰减率低至0.035%。这项工作开发了一种简便的无氨方法来制备超细VN纳米颗粒，以改善Li-S电池的电化学性能。
