材料科学
上部结构
阴极
中子衍射
衍射
电化学
透射电子显微镜
超单元
相(物质)
选区衍射
电子衍射
离子
高分辨率透射电子显微镜
化学工程
纳米技术
结晶学
电极
物理化学
光学
工程类
地质学
物理
有机化学
化学
海洋学
雷雨
量子力学
作者
Zheng-Yao Li,Xiaobai Ma,И.А. Бобриков,Kai Sun,Hongliang Wang,Linfeng He,Yuqing Li,Dongfeng Chen
标识
DOI:10.1021/acsami.1c20757
摘要
Layered cathodes have been recognized as potential advanced candidates for sodium-ion batteries (SIBs), but the poor electrochemical performance has seriously hindered their further development. Herein, an ordered Na2/3[Ni2/9Mg1/9Mn5/9Ti1/9]O2 (NMMT) is designed and investigated as a high-performance cathode for SIBs through the synergistic effect of Mg and Ti codoping. Compared to the single Mg- or Ti-doped materials, NMMT clearly exhibits superstructure ordering diffraction peaks, and neutron diffraction further confirms that the diffraction peaks can be well indexed by a larger supercell P63, rather than the common unit cell P63/mmc by X-ray diffraction (XRD). High-resolution transmission electron microscopy also approves the ordering arrangement. This material shows an obvious capacity activation process during the first cycles, thus delivering 113 mA h g-1 specific capacity at 0.1 C (close to the theoretical value). Excellent rate capability even at 15 C and cycling stability after 500 cycles between 2.0 and 4.3 V can also be achieved, indicating that an ordered cathode is still promising. Besides, a single-phase reaction mechanism is revealed by ex situ/in situ XRD experiments. This study offers some insights into the material design and characterization of layered oxide cathodes for high-performance SIBs in the future.
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