State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , 1295 Dingxi Road, Shanghai 200050, China.
ACS Appl Mater Interfaces. 2014 Dec 10;6(23):21567-75. doi: 10.1021/am506564n. Epub 2014 Nov 24.
Surface defects on carbon nanotube cathodes have been artificially introduced by bombardment with argon plasma. Their roles in the electrochemical performance of rechargeable Li-O2 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-O2 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-O2 batteries if they are combined with a helpful electrolyte solvent such as PP13TFSI.
通过氩等离子体轰击在碳纳米管阴极上人为引入表面缺陷。研究了它们在可再充电 Li-O2 电池中的电化学性能中的作用。在基于四乙二醇二甲醚 (TEGDME) 和 N-甲基-N-丙基哌啶双（三氟甲烷磺酰基）亚胺 (PP13TFSI) 的电解质的电池中，缺陷增加了 Li2O2 颗粒生长的成核位点数量，并减小了形成的颗粒的尺寸。这导致放电容量增加和循环过电位降低。然而，在前一种电池中，缺陷诱导的亲水性表面促进了碳酸盐的形成，这对 Li-O2 电池的循环性能产生了不利影响。相比之下，在后一种情况下，缺陷阴极促进了 Li2O2 的形成，而不会增强阴极表面上碳酸盐的形成，从而延长了循环寿命。这很可能归因于离子液体对阴极表面官能团施加的钝化作用。这些结果表明，如果碳表面的缺陷与有益的电解质溶剂（如 PP13TFSI）结合使用，它们可能对 Li-O2 电池的循环性能产生积极影响。
