Department of Materials Science and Engineering, Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul, Republic of Korea.
Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul National University, Seoul, Republic of Korea.
Nat Mater. 2022 Jun;21(6):664-672. doi: 10.1038/s41563-022-01209-1. Epub 2022 Mar 17.
Lattice oxygen redox offers an unexplored way to access superior electrochemical properties of transition metal oxides (TMOs) for rechargeable batteries. However, the reaction is often accompanied by unfavourable structural transformations and persistent electrochemical degradation, thereby precluding the practical application of this strategy. Here we explore the close interplay between the local structural change and oxygen electrochemistry during short- and long-term battery operation for layered TMOs. The substantially distinct evolution of the oxygen-redox activity and reversibility are demonstrated to stem from the different cation-migration mechanisms during the dynamic de/intercalation process. We show that the π stabilization on the oxygen oxidation initially aids in the reversibility of the oxygen redox and is predominant in the absence of cation migrations; however, the π-interacting oxygen is gradually replaced by σ-interacting oxygen that triggers the formation of O-O dimers and structural destabilization as cycling progresses. More importantly, it is revealed that the distinct cation-migration paths available in the layered TMOs govern the conversion kinetics from π to σ interactions. These findings constitute a step forward in unravelling the correlation between the local structural evolution and the reversibility of oxygen electrochemistry and provide guidance for further development of oxygen-redox layered electrode materials.
晶格氧氧化还原为可充电电池提供了一种探索过渡金属氧化物 (TMO) 优越电化学性能的新途径。然而，该反应通常伴随着不利的结构转变和持续的电化学降解，从而阻碍了该策略的实际应用。在这里，我们探索了层状 TMO 在短时间和长时间电池运行过程中局部结构变化和氧电化学之间的紧密相互作用。结果表明，氧氧化还原活性和可逆性的显著不同源于动态脱插过程中不同的阳离子迁移机制。我们表明，氧氧化过程中的π 稳定作用最初有助于氧氧化还原的可逆性，在没有阳离子迁移的情况下占主导地位；然而，随着循环的进行，与π 相互作用的氧逐渐被触发 O-O 二聚体形成和结构失稳的σ 相互作用氧取代。更重要的是，揭示了层状 TMO 中可用的不同阳离子迁移路径控制着从π 相互作用到σ 相互作用的转化动力学。这些发现为揭示局部结构演变与氧电化学可逆性之间的相关性迈出了一步，并为进一步开发氧氧化还原层状电极材料提供了指导。
