非水溶剂锂-空气电池中的氧气电极反应

Oxygen Electrode Reactions in Nonaqueous Li-Air Batteries

基于锂-氧气反应的锂-空气电池在所有的锂电池体系中具有最大的理论容量和能量密度,认识锂-空气电池中的氧气电极反应对锂-空气电池的研发具有指导意义。本文以金电极/乙腈电解液为模型体系,介绍了锂-空气电池在放电和充电过程中的氧气电极反应机理。电池放电时,氧气还原成超氧自由基,超氧自由基与锂离子结合生成不稳定的超氧化锂;通过歧化反应,超氧化锂生成放电反应最终产物过氧化锂。电池充电时,过氧化锂通过一步两电子直接氧化生成氧气,不经过超氧化锂中间态。在阐述氧气电极反应机理的同时,还对研究氧气反应的各种电化学方法作了介绍。

Li-air batteries utilizing Li-O2 reactions have the highest theoretical capacity and energy density in the Li-battery family, and potentially have the ability to transform energy storage. Thus, it is crucial to understand the oxygen reaction mechanism in Li＋ electrolyte because it is the core reaction occurring in the Liair ceils currently under intense R＆D. This review summarized the oxygen reaction mechanism during discharge and charge of a nonaqueous Li-air cell by taking Au/CH3 CN as a model system： On discharge, O2 is reduced to O2, which then forms LiO2 on the electrode surface which disproportionates to Li2O2. On charging, Li2O2 decomposes directly, in a one-step reaction to evolve O2 and does not pass through LiO2 as an intermediate. Along with presenting the oxygen reaction mechanism, the relevant electrochemical methods are also described.