Elucidating the Mechanism of Oxygen Reduction for Lithium-Air Battery Applications

作者：Cormac O. Laoire, Sanjeev Mukerjee, K. M. Abraham, Edward J. Plichta, Mary A. Hendrickson · 发表于：The Journal of Physical Chemistry C · 年份：2009 · DOI：10.1021/jp908090s · 被引用次数：667 · 研究领域：Advanced Battery Materials and Technologies、Conducting polymers and applications、Advanced battery technologies research

Unlocking the true energy capabilities of the lithium metal negative electrode in a lithium battery has until now been limited by the low capacity intercalation and conversion reactions at the positive electrodes. Abraham et al. (Abraham, K. M.; Jiang, Z. J. Electrochem. Soc. 1996, 143, 1−5) overcame this limitation by removing these electrodes and allowing lithium to react directly with oxygen in the atmosphere, forming the Li-air battery. The Li/O 2 battery redox couple has a theoretical specific energy of 5200 W h/kg and represents the ultimate, environmentally friendly electrochemical power source. In this work, we report for the first time the intimate role of electrolyte, in particular the role of ion conducting salts, in determining the reversibility and kinetics of oxygen reduction in nonaqueous electrolytes designed for such applications. Such fundamental understanding of this high energy density battery is crucial to harnessing its full energy potential. The kinetics and mechanisms of O 2 reduction in solutions of hexafluorophosphate of the general formula A + PF 6 −, where A = tetrabutylammonium (TBA), K, Na, and Li, in acetonitrile are reported on glassy carbon electrodes using cyclic voltammetry (CV) and rotating disk electrode (RDE) techniques. The results show that the cations in the electrolyte strongly influence the reduction mechanism of O 2 . Larger cations represented by TBA salts displayed reversible O 2 /O 2 − redox couple, in contrast to those containin...