Positive Role of Surface Defects on Carbon Nanotube Cathodes in Overpotential and Capacity Retention of Rechargeable Lithium鈥揙xygen Batteries

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• 作者：Shiting Huang ; Wugang Fan ; Xiangxin Guo ; Fanhao Meng ; Xuanyong Liu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2014
• 出版时间：December 10, 2014
• 年：2014
• 卷：6
• 期：23
• 页码：21567-21575
• 全文大小：800K
• ISSN：1944-8252

文摘

Surface defects on carbon nanotube cathodes have been artificially introduced by bombardment with argon plasma. Their roles in the electrochemical performance of rechargeable Li鈥揙₂ batteries have been investigated. In batteries with tetraethylene glycol dimethyl ether (TEGDME)- and N-methyl-N-propylpiperidinium bis(trifluoromethansulfonyl)imide (PP13TFSI)-based electrolytes, the defects increase the number of nucleation sites for the growth of Li₂O₂ particles and reduce the size of the formed particles. This leads to increased discharge capacity and reduced cycle overpotential. However, in the former batteries, the hydrophilic surfaces induced by the defects promote carbonate formation, which imposes a deteriorating effect on the cycle performance of the Li鈥揙₂ batteries. In contrast, in the latter case, the defective cathodes promote Li₂O₂ formation without enhancing formation of carbonates on the cathode surfaces, resulting in extended cycle life. This is most probably attributable to the passivation effect on the functional groups of the cathode surfaces imposed by the ionic liquid. These results indicate that defects on carbon surfaces may have a positive effect on the cycle performance of Li鈥揙₂ batteries if they are combined with a helpful electrolyte solvent such as PP13TFSI.

Keywords:

surface defects; argon-plasma bombardment; carbonate species; lithium鈭抩xygen batteries; carbon nanotubes; lithium peroxides