氧化还原
材料科学
阴极
各向异性
格子(音乐)
失真(音乐)
价(化学)
电极
化学物理
晶格扩散系数
纳米技术
活化能
电子能带结构
电子
凝聚态物理
带隙
电化学
无机化学
电极电位
标准电极电位
热传导
晶格能
结构稳定性
半反应
电子转移
化学
作者
Huangxu Li,Xu Wang,Fangyan Liu,Yulun Wu,Jingqiang Zheng,Zezhou Lin,Tiancheng Liu,Jin Xiao,Jianzhong Jiang,Haitao Huang
出处
期刊:ACS Nano
[American Chemical Society]
日期:2025-10-03
卷期号:19 (40): 35712-35723
被引量:5
标识
DOI:10.1021/acsnano.5c12007
摘要
Fe- and Mn-based polyanionic electrode materials are important cathode materials for sodium-ion batteries (SIBs) due to their low cost. However, due to the low redox potential of Fe2+/3+ and the notorious Jahn–Teller (JT) effect, severe lattice distortion that is associated with Mn2+/3+ redox hinders Fe and Mn redox activation, leading to inadequate cycling stability and rate performance. Here, we discover both high Mn2+/3+ and Fe2+/3+ redox activation in a Na4Mn1.5Fe1.5(PO4)2(P2O7) (NMFPP) material. It is revealed that the substitution of Mn reduces the Fe–O bond covalency, elevating the Fe2+/3+ redox potential to improve the energy density. Furthermore, the JT effect is accompanied by Mn eg orbital splitting, with the dx2–y2 and dz2 orbitals being positioned at the top of the valence band and the bottom of the conduction band, respectively, which primary contributes to reduce the material band gap and facilitate electron transfer. Experimental and theoretical studies discover an anisotropic lattice distortion behavior, which enlarges Na+ diffusion pathways, lowering diffusion energy barriers and enabling rapid Na+ migration. As a consequence, high Fe–Mn redox activity is achieved and the NMFPP demonstrates enhanced energy density, rate performance, and exceptional cycling stability for sodium storage. These findings prove that the JT effect and lattice distortion could synergistically make positive impacts on transition-metal redox activation, which is informative for the design of high-performance electrode materials.
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