A Composite of Carbon-Wrapped Mo₂C Nanoparticle and Carbon Nanotube Formed Directly on Ni Foam as a High-Performance Binder-Free Cathode for Li-O₂ Batteries

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• 作者：Qian-Cheng Zhu ; Shu-Mao Xu ; Michelle M. Harris ; Chao Ma ; Yu-Si Liu ; Xiao Wei ; Hua-Sheng Xu ; Yong-Xian Zhou ; Yu-Cai Cao ; Kai-Xue Wang and Jie-Sheng Chen
• 刊名：Advanced Functional Materials
• 出版年：2016
• 出版时间：December 13, 2016
• 年：2016
• 卷：26
• 期：46
• 页码：8514-8520
• 全文大小：1466K
• ISSN：1616-3028

文摘

Cathode design is indispensable for building Li-O₂ batteries with long cycle life. A composite of carbon-wrapped Mo₂C nanoparticles and carbon nanotubes is prepared on Ni foam by direct hydrolysis and carbonization of a gel composed of ammonium heptamolybdate tetrahydrate and hydroquinone resin. The Mo₂C nanoparticles with well-controlled particle size act as a highly active oxygen reduction reactions/oxygen evolution reactions (ORR/OER) catalyst. The carbon coating can prevent the aggregation of the Mo₂C nanoparticles. The even distribution of Mo₂C nanoparticles results in the homogenous formation of discharge products. The skeleton of porous carbon with carbon nanotubes protrudes from the composite, resulting in extra voids when applied as a cathode for Li-O₂ batteries. The batteries deliver a high discharge capacity of ≈10 400 mAh g⁻¹ and a low average charge voltage of ≈4.0 V at 200 mA g⁻¹. With a cutoff capacity of 1000 mAh g⁻¹, the Li-O₂ batteries exhibit excellent charge–discharge cycling stability for over 300 cycles. The average potential polarization of discharge/charge gaps is only ≈0.9 V, demonstrating the high ORR and OER activities of these Mo₂C nanoparticles. The excellent cycling stability and low potential polarization provide new insights into the design of highly reversible and efficient cathode materials for Li-O₂ batteries.