Layered Na_xTMO₂ (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 Na_xTMO₂ materials is normally reasoned by unfavorable structural phase transitions accompanied by the slide of TMO₂ layers, while the shrinkage and expansion of TMO₂ layers is still unclear. P3-type Na_0.67Mn_0.67Ni_0.33O₂, synthesized at 750 ˚C and demonstrating attractive electrochemical behavior, is investigated by X-ray absorption spectroscopy (XAS). Experimental results explain changes in interatomic distance and bond angle of TMO₆ units 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 various TMO₆ units resulting in stress in the overall structure and capacity fading.

层状Na _x TM O ₂（0 <x≤1，TM =过渡金属）材料已被广泛研究作为钠离子电池的阴极。但是，循环过程中的容量衰减会阻碍其在钠离子电池中的实际使用。层状的Na衰落的能力_X TM Ò _2种材料通常是通过伴随的滑动不利结构相变的理由TM Ò ₂层，而的收缩和膨胀TM ö ₂层目前还不清楚。P3型Na _0.67 Mn _0.67 Ni _0.33 O ₂用X射线吸收光谱法（XAS）研究了在750℃合成的具有良好电化学行为的，。实验结果解释了P3型材料循环过程中TM O ₆单元的原子间距离和键角的变化。由于Mn和Ni有序排列，观察到P3型材料中Ni周围的Na优先占据，这导致了各种TM O ₆单元的尺寸发生变化，从而导致整体结构中的应力和容量衰减。