Zuo Wenhua, Qiu Jimin, Liu Xiangsi, Ren Fucheng, Liu Haodong, He Huajin, Luo Chong, Li Jialin, Ortiz Gregorio F, Duan Huanan, Liu Jinping, Wang Ming-Sheng, Li Yangxing, Fu Riqiang, Yang Yong
State Key Laboratory for Physical Chemistry of Solid Surfaces, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, People's Republic of China.
School of Energy Research, Xiamen University, 361005, Xiamen, People's Republic of China.
Nat Commun. 2020 Jul 15;11(1):3544. doi: 10.1038/s41467-020-17290-6.
Air-stability is one of the most important considerations for the practical application of electrode materials in energy-harvesting/storage devices, ranging from solar cells to rechargeable batteries. The promising P2-layered sodium transition metal oxides (P2-NaTmO) often suffer from structural/chemical transformations when contacted with moist air. However, these elaborate transitions and the evaluation rules towards air-stable P2-NaTmO have not yet been clearly elucidated. Herein, taking P2-NaMnO and P2-NaNiMnO as key examples, we unveil the comprehensive structural/chemical degradation mechanisms of P2-NaTmO in different ambient atmospheres by using various microscopic/spectroscopic characterizations and first-principle calculations. The extent of bulk structural/chemical transformation of P2-NaTmO is determined by the amount of extracted Na, which is mainly compensated by Na/H exchange. By expanding our study to a series of Mn-based oxides, we reveal that the air-stability of P2-NaTmO is highly related to their oxidation features in the first charge process and further propose a practical evaluating rule associated with redox couples for air-stable NaTmO cathodes.
对于电极材料在从太阳能电池到可充电电池等能量收集/存储设备中的实际应用而言，空气稳定性是最重要的考虑因素之一。有前景的P2层状钠过渡金属氧化物（P2-NaTmO）在与潮湿空气接触时常常会发生结构/化学转变。然而，这些复杂的转变以及针对空气稳定的P2-NaTmO的评估规则尚未得到清晰阐明。在此，以P2-NaMnO和P2-NaNiMnO为关键示例，我们通过使用各种微观/光谱表征和第一性原理计算，揭示了P2-NaTmO在不同环境气氛中的全面结构/化学降解机制。P2-NaTmO的整体结构/化学转变程度由提取的Na的量决定，其主要通过Na/H交换来补偿。通过将我们的研究扩展到一系列锰基氧化物，我们揭示了P2-NaTmO的空气稳定性与其首次充电过程中的氧化特性高度相关，并进一步提出了一种与氧化还原对相关的实用评估规则，用于评估空气稳定的NaTmO阴极。
