Investigations of Fundamental Li-O2 Electrochemistry by In Situ Liquid Cell Transmission Electron Microscopy

利用原位液胞透射电子显微镜，我们成功地实时和实时地研究了Li-O2电池的反应动力学。直观地显示了电极-电解液界面上与固体Li2O_2相的形成和分解有关的纳米级反应。我们发现放电和充电率对Li-O2反应的基本机理有显著影响。在低速率下，Li-O2反应以溶液机制进行，形成厚度为~500 nm的Li2O2层。而在高过电位条件下，通过电极表面快速钝化的表面机制形成了非常薄的Li2O2层。这些发现促进了我们对基础Li-O2电化学的理解。

Using in situ liquid cell transmission electron microscopy, we have successfully investigated the reaction dynamics of Li-O2 battery in real-time and real-space. The nanoscale reactions at the electrode-electrolyte interfaces, associated with the formation and decomposition of solid Li2O2 phase, were directly visualized. We found that discharge and charge rate can significantly affect the fundamental mechanisms of Li-O2 reactions. At low rates, the Li-O2 reaction proceeds via a solution mechanism with the formation of Li2O2 layers as thick as ~500 nm. While under high overpotential conditions, a very thin Li2O2 layer forms through a surface mechanism with fast passivation of the electrode surfaces. These findings have advanced our understandings of the fundamental Li-O2 electrochemistry.