Because of the low cost and high abundance of sodium, room-temperature sodium-ion batteries have recently been considered as an alternative power source to lithium-ion batteries. In contrast to the electrochemical performance of the batteries, safety has been paid much less attention, but safety is a critical consideration because sodium-ion batteries are intended for large-scale electrochemical energy storage applications. Herein, we have reported a NaNi_1/3Fe_1/3Mn_1/3O₂/hard carbon full cell with a good cycling performance and high Coulombic efficiency. The energy density of this pouch cell is close to 95 Wh/kg, and the capacity retention of the NFM full cell attained at 92.6% after 100 cycle numbers. Moreover, we have further used accelerating rate calorimetry, scanning electron microscopy, and operando synchrotron high-energy X-ray diffraction to investigate the thermal/chemical stability of charged Na_xNi_1/3Fe_1/3Mn_1/3O₂ cathode material at both cell and component level. It is found that the thermal decomposition of desodiated Na_xNi_1/3Fe_1/3Mn_1/3O₂ is a redox reaction that can be facilitated with the presence of either a reductive environment, such as electrolytes, or a strong oxidative environment that can result from a higher degree of desodiation. The findings presented in this work can guide future development of advanced sodium-ion batteries for practical application.

中文翻译：

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Na _x Ni _1/3 Fe _1/3 Mn _1/3 O ₂阴极材料对安全钠离子电池的热稳定性和化学稳定性的探讨

由于钠的低成本和高丰度，最近已考虑将室温钠离子电池作为锂离子电池的替代电源。与电池的电化学性能相比，安全性受到的关注要少得多，但是安全性是至关重要的考虑因素，因为钠离子电池旨在用于大规模的电化学储能应用。在这里，我们报道了NaNi _1/3 Fe _1/3 Mn _1/3 O ₂/硬碳全电池，具有良好的循环性能和高库仑效率。该袋式电池的能量密度接近95 Wh / kg，经过100次循环后，NFM满电池的容量保持率达到92.6％。此外，我们还使用了加速量热法，扫描电子显微镜和操作同步加速器高能X射线衍射技术来研究带电的Na _x Ni _1/3 Fe _1/3 Mn _1/3 O ₂阴极的热/化学稳定性。单元和组件级别的材料。发现脱氮的Na _x Ni _1/3 Fe _1/3 Mn _1/3 O ₂的热分解氧化还原反应是一种氧化还原反应，可通过存在还原性环境（例如电解质）或强氧化性环境（可能由较高的脱氧度导致）来促进。这项工作中提出的发现可以指导高级钠离子电池在实际应用中的未来发展。