兴奋剂
材料科学
涂层
阴极
离子
结构稳定性
过渡金属
电化学
复合材料
化学工程
分析化学(期刊)
化学
光电子学
电极
物理化学
工程类
结构工程
生物化学
催化作用
有机化学
色谱法
作者
Yang Yu,Weijin Kong,Qingyuan Li,De Ning,Götz Schuck,G. Schumacher,Chunjian Su,Xiangfeng Liu
出处
期刊:ACS applied energy materials
[American Chemical Society]
日期:2020-01-03
卷期号:3 (1): 933-942
被引量:114
标识
DOI:10.1021/acsaem.9b02021
摘要
O3-type NaTMO2 (TM = transition metal) as cathodes for Na-ion batteries have aroused much interest. But the structural instability during charge–discharge cycles and the inferior rate capability restricts their application. In this study, we report a synergetic modification method to simultaneously increase the rate capacity and cycling stability of O3-type NaMn0.33Fe0.33Ni0.33O2(MFN) cathode material by integrating TiO2 coating and Ti4+ doping. Moreover, the synergetic mechanism has been put forward. First, the TiO2-coating layer prevents the side reactions on the surface, which can retain the structural integrity and stability. Second, TiO2-coating induces Ti4+ doping which enlarges Na–O and increases the interslab spacing d. This raises the Na+ diffusion coefficient and improves the rate performance. Third, because of the large Ti–O bond energy, the TM–O bond shrinks when Ti4+ is doped into the transition metal site. O–O is also shortened due to the Ti doping. TMO2 slabs are compressed, which benefits the structural stability and the cyclic property. Fourth, Ti doping accompanying TiO2 coating decreases Mn3+/Mn4+ and mitigates the Jahn–Teller effect. This increases the stability of the layered structure. The understanding of the multiroles of TiO2 coating is equally instructive for the exploration of other cathode materials for Na-ion or Li-ion batteries.
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