Shanghai Electrochemical Energy Devices Research Center, Department of Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China.
Key Laboratory for Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Nanjing 210094, People's Republic of China.
Nano Lett. 2023 Mar 8;23(5):1743-1751. doi: 10.1021/acs.nanolett.2c04465. Epub 2023 Feb 22.
P2-NaNiMnO represents a promising cathode for Na-ion batteries, but it suffers from severe structural degradation upon storing in a humid atmosphere and cycling at a high cutoff voltage. Here we propose an in situ construction to achieve simultaneous material synthesis and Mg/Sn cosubstitution of NaNiMnO via one-pot solid-state sintering. The materials exhibit superior structural reversibility and moisture insensitivity. In-operando XRD reveals an essential correlation between cycling stability and phase reversibility, whereas Mg substitution suppressed the P2-O2 phase transition by forming a new Z phase, and Mg/Sn cosubstitution enhanced the P2-Z transition reversibility benefiting from strong Sn-O bonds. DFT calculations disclosed high chemical tolerance to moisture, as the adsorption energy to HO was lower than that of the pure NaNiMnO. A representative NaNiMgMnSnO cathode exhibits high reversible capacities of 123 mAh g (10 mA g), 110 mAh g (200 mA g), and 100 mAh g (500 mA g) and a high capacity retention of 80% (500 mA g, 500 cycles).
P2-NaNiMnO 是一种很有前途的钠离子电池正极材料，但在高截止电压下存储于高湿度环境中时，其结构会严重降解。在这里，我们通过一步固相烧结法提出了一种原位构建方法，实现了 NaNiMnO 的同时材料合成和 Mg/Sn 共取代。该材料表现出优异的结构可逆性和抗湿能力。原位 XRD 揭示了循环稳定性和相可逆性之间的基本相关性，而 Mg 取代通过形成新的 Z 相抑制了 P2-O2 相变，并且 Mg/Sn 共取代增强了 P2-Z 转变的可逆性，这得益于强 Sn-O 键。DFT 计算表明该材料对水分具有较高的化学耐受性，因为其对 HO 的吸附能低于纯 NaNiMnO。一个代表性的 NaNiMgMnSnO 正极材料在 10 mA g（10 mA g）、200 mA g（200 mA g）和 500 mA g（500 mA g）的电流密度下分别表现出 123 mAh g、110 mAh g 和 100 mAh g 的可逆容量以及 80%的容量保持率（500 mA g，500 个循环）。
