Zhang Zichang, Liu Jiahui, Du Peng-Hu, Xia Dingguo, Sun Qiang
School of Materials Science and Engineering, Peking University, Beijing 100871, China.
Beijing Key Laboratory of Theory and Technology for Advanced Batteries Materials, Peking University, Beijing 100871, China.
ACS Nano. 2024 Nov 5;18(44):30584-30592. doi: 10.1021/acsnano.4c09285. Epub 2024 Oct 27.
The practical application of Na-ion cathode materials is currently restricted by their low energy density and sluggish dynamics, while the cation-disordered rocksalt (DRX) structures offer a possible solution to the challenge. In this study, among the 24 candidates containing elements, we use mixing temperature as a descriptor to screen the synthesizable Na-excess DRX, and we have identified NaMnMoO as the most promising candidate that exhibits a Na percolating fraction of 53%, which is higher than that of LiMnTiO (35%) proposed in the previous study due to the larger lattice constant in Na-excess DRX cathodes. More importantly, NaMnMoO is predicted to have a capacity of 228 mAh/g with an energy density of 552 Wh/kg derived from percolation theory and cluster-expansion Monte Carlo simulations, which is higher than that of NaNbMnO and NaMnTiO synthesized recently. For a better understanding, the redox mechanism is explored, which involves Mo/Mo, Mn/Mn, and O/O (0 < < 2), indicating the participation of anionic redox. Meanwhile, the Na diffusion prefers a divacancy mechanism via an o-t-o diffusion channel with a low diffusion barrier of 0.29 eV. This study expands the family of DRX for the cathode of Na-ion batteries with enhanced performance.
钠离子阴极材料的实际应用目前受到其低能量密度和缓慢动力学的限制，而阳离子无序岩盐（DRX）结构为应对这一挑战提供了一种可能的解决方案。在本研究中，在包含多种元素的24种候选材料中，我们使用混合温度作为描述符来筛选可合成的富钠DRX，并且我们已经确定NaMnMoO是最有前景的候选材料，其呈现出53%的钠渗流分数，由于富钠DRX阴极中更大的晶格常数，该分数高于先前研究中提出的LiMnTiO（35%）。更重要的是，根据渗流理论和团簇展开蒙特卡罗模拟预测，NaMnMoO具有228 mAh/g的容量和552 Wh/kg的能量密度，这高于最近合成的NaNbMnO和NaMnTiO。为了更好地理解，我们探索了氧化还原机制，其涉及Mo/Mo、Mn/Mn和O/O（0 << 2），表明存在阴离子氧化还原的参与。同时，钠扩散更倾向于通过具有0.29 eV低扩散势垒的o-t-o扩散通道的双空位机制。本研究扩展了用于高性能钠离子电池阴极的DRX家族。
