Preferential occupation of Na in P3-type layered cathode material for sodium ion batteries
Preferential occupation of Na in P3-type layered cathode material for sodium ion batteries
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DOI：
10.1016/j.nanoen.2020.104535
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发表时间：
2020-04
期刊：
影响因子：
17.6
通讯作者：
Li Zhang;Jun Wang;Jinke Li;G. Schuck;M. Winter;G. Schumacher;Jie Li
中科院分区：
文献类型：
--
作者：
Li Zhang;Jun Wang;Jinke Li;G. Schuck;M. Winter;G. Schumacher;Jie Li
层状NaxTMO2（0 < x ≤ 1，TM=过渡金属）材料作为钠离子电池的阴极已被广泛研究。然而，在循环过程中容量衰减阻碍了它们在钠离子电池中的实际应用。层状NaxTMO2材料的容量衰减通常是由于TMO2层的滑移引起的不利的结构相变引起的，而TMO2层的收缩和膨胀尚不清楚。通过X射线吸收光谱（XAS）研究了在750 °C下合成的P3型Na 0.67Mn 0.67Ni 0.33O2的电化学行为。实验结果解释了P3型材料在循环过程中TMO 6单元的原子间距离和键角的变化。由于Mn和Ni的有序排列，Na优先占据P3型材料中Ni周围，这是导致不同TMO6单元不同尺寸变化的原因，从而导致整体结构中的应力和容量衰减。
Layered NaxTMO2(0 < x ≤ 1,TM= transition metal) materials have been extensively investigated as cathodes for sodium ion batteries. However, capacity fading during cycling hinders their practical utilization in sodium ion batteries. The capacity fading of layered NaxTMO2materials is normally reasoned by unfavorable structural phase transitions accompanied by the slide ofTMO2layers, while the shrinkage and expansion ofTMO2layers is still unclear. P3-type Na0.67Mn0.67Ni0.33O2, synthesized at 750 °C and demonstrating attractive electrochemical behaviour, is investigated by X-ray absorption spectroscopy (XAS). Experimental results explain changes in interatomic distance and bond angle ofTMO6units during cycling of P3-type material. The preferential occupancy of Na around Ni in P3-type material is observed as a result of an ordered arrangement of Mn and Ni, which is responsible for different dimensional changes of variousTMO6units resulting in stress in the overall structure and capacity fading.