Decorating ketjen black with ultra-small Mo2C nanoparticles to enhance polysulfides chemisorption and redox kinetics for lithium-sulfur batteries

• 来源期刊: 能源化学
• 年，卷（期）: 2020,（12）
• 页码范围: 207-215
• 页数: 9页
• 语种: 英文

摘要

The low sulfur utilization and fast capacity fading resulting from the sluggish redox reaction and abom-inable polysulfides shuttle greatly hinder the practical applications of lithium-sulfur(Li-S)batteries.Herein,we develop a facile "in-situ growth" method to decorate ultra-small M02C nanoparticles(US-M02C)on the surface of Ketjen Black(KB)to functionalize the commercial polypropylene(PP)separators,which can accelerate the redox kinetics of lithium polysulfides conversion and effectively increase the utilization of sulfur for Li-S batteries.Importantly,the US-M02C nanoparticles have abundant sites for chemical adsorption towards polysulfides and the conductive carbon networks of KB have cross-linked pore channels,which can promote electron transport and provide physical barrier and volume expansion space for polysulfides.Due to the combined effects of the US-Mo2C and KB,Li-S cells employing the mul-tifunctional PP separators modified with KB/US-Mo2C composite(KB/US-Mo2C@PP)exhibit a high specific capacity(1212.8 mAh g-1 at 0.2 C),and maintain a reversible capacity of 1053.3 mAh g-1 after 100 cycles.More importantly,the KB/US-Mo2C@PP cells with higher sulfur mass loading of 4.9 mg cm-2 have superb areal capacity of 2.3 mAh cm-2.This work offers a novel and promising perspective for high-performance Li-S batteries from both the shuttle effect and the complex polysulfides conversion.