First-principles comparative study of Cr migration in O3 and O/P hybrid-phased NaCrO2
First-principles comparative study of Cr migration in O3 and O/P hybrid-phased NaCrO2
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DOI：
10.1103/physrevmaterials.6.095403
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发表时间：
2022-09
影响因子：
3.4
通讯作者：
Jialiang Wei;L. Shaw;Wei Chen
中科院分区：
文献类型：
--
作者：
Jialiang Wei;L. Shaw;Wei Chen
在层状Na过渡金属氧化物（TM）中，TM迁移通常发生在高电荷状态，严重恶化了容量和可逆性。同时，在高荷电态下，八面体（o型）和棱柱体（p型）钠层共生形成杂化相。这些杂化相通常比简单的O3或P3堆叠更稳定。然而，对TM在这些杂交阶段的迁移机制和影响知之甚少。在这项工作中，进行了比较第一性原理研究，以了解层状O3和混合相结构变化与Cr迁移之间的联系。Cr迁移后，杂化相的层收缩比O3相大。影响Cr迁移能的因素有三个：Na浓度、局部三维构型和二维平面几何形状。低钠浓度和某些局部三维构型有利于Cr的迁移。在O3和混合相中，Cr迁移障碍均与温度呈正相关。研究了Cr在17种掺杂O3和杂化相中的迁移。在这些掺杂中，Cr - o键长度分布更均匀通常表明Cr迁移受到抑制。通过对Cr和掺杂剂的综合考虑，确定了抑制Cr迁移的最佳掺杂剂。我们对Cr在O3和杂相结构中的迁移进行了比较研究，揭示了杂相结构在层状阴极材料发展中的重要作用。
In layered Na transition-metal (TM) oxides, TM migration usually occurs at highly charged states and severely deteriorates the capacity and reversibility. Meanwhile, the formation of hybrid phases with the intergrowth of octahedral (O-type) and prismatic (P-type) Na layers also takes place at highly charged states. These hybrid phases are often more stable than simple O3 or P3 stackings. However, little is known about the mechanism and impact of TM migration in these hybrid phases. In this work, a comparative first-principles study is performed to understand the connections between structural changes and Cr migration in layered O3 and hybrid-phased. After Cr migration, the hybrid-phasedsuffers from greater layer shrinkage than the O3 phase. Three factors affect the Cr migration energy: the Na concentration, local 3D configurations, and 2D in-plane geometries. Low Na concentrations and certain local 3D configurations facilitate the Cr migration. The Cr migration barriers in both O3 and hybrid-phasedare positively correlated with the. The Cr migration in 17 doped O3 and hybrid-phasedis surveyed. In these doped, a more uniform distribution of the Cr–O bond lengths usually suggests suppressed Cr migration. Optimal dopants for suppressing Cr migration are identified by consideringfor both Cr and the dopant. Our comparative study on Cr migration in O3 and hybrid-phasedreveals the significant role of hybrid-phased structures in the development of layered cathode materials.