氧化还原
材料科学
上部结构
锂(药物)
氧气
过渡金属
化学
金属
离子
丝带
化学物理
无机化学
催化作用
热力学
有机化学
复合材料
冶金
内分泌学
物理
医学
生物化学
作者
Eun Jeong Kim,Philip A. Maughan,Euan N. Bassey,Raphaële J. Clément,Le Anh,Laurent C. Duda,Divya Sehrawat,Reza Younesi,Neeraj Sharma,Clare P. Grey,A. Robert Armstrong
标识
DOI:10.1002/aenm.202102325
摘要
Abstract Activation of oxygen redox represents a promising strategy to enhance the energy density of positive electrode materials in both lithium and sodium‐ion batteries. However, the large voltage hysteresis associated with oxidation of oxygen anions during the first charge represents a significant challenge. Here, P3‐type Na 0.67 Li 0.2 Mn 0.8 O 2 is reinvestigated and a ribbon superlattice is identified for the first time in P3‐type materials. The ribbon superstructure is maintained over cycling with very minor unit cell volume changes in the bulk while Li ions migrate reversibly between the transition metal and Na layers at the atomic scale. In addition, a range of spectroscopic techniques reveal that a strongly hybridized Mn 3d–O 2p favors ligand‐to‐metal charge transfer, also described as a reductive coupling mechanism, to stabilize reversible oxygen redox. By preparing materials under three different synthetic conditions, the degree of ordering between Li and Mn is varied. The sample with the maximum cation ordering delivers the largest capacity regardless of the voltage windows applied. These findings highlight the importance of cationic ordering in the transition metal layers, which can be tuned by synthetic control to enhance anionic redox and hence energy density in rechargeable batteries.
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