A P2-Na0.67Co0.5Mn0.5O2 Cathode Material With Excellent Rate ...

A P2-Na0.67Co0.5Mn0.5O2 cathode material with excellent rate capability and cycling stability for sodium ion batteries†

Yuan-En Zhu,‡a Xingguo Qi,‡b Xiaoqing Chen,a Xianlong Zhou,a Xu Zhang,a Jinping Wei,a Yongsheng Hub and Zhen Zhou *a Author affiliations

* Corresponding authors

a Tianjin Key Laboratory of Metal and Molecule Based Material Chemistry, Institute of New Energy Material Chemistry, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Materials Science and Engineering, National Institute for Advanced Materials, Nankai University, Tianjin 300350, China E-mail: [email protected]

b Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

Abstract

Sodium ion batteries are considered as next-generation energy storage devices; however, stable cathode materials are highly desirable and challenging for sodium ion batteries. Herein, we report the preparation of a layered cathode material, P2-Na0.67Co0.5Mn0.5O2, with a hierarchical architecture, through a facile and simple sol–gel route. X-ray diffraction (XRD) and high resolution transmission electron microscopy elucidated a well-defined P2-type phase structure, and in situ XRD measurements provided further evidence about the structural stability during desodiation/sodiation. Benefiting from the structural stability, the cathode material delivered a high discharge capacity of 147 mA h g−1 at 0.1C rate, and excellent cyclic stability with nearly 100% capacity retention over at least 100 cycles at 1C. More importantly, 88 mA h g−1 was maintained when the electrode was cycled at a very high rate of 30C, and almost half of its capacity was retained over 2000 cycles, which outperforms all the reported P2-type cathode materials. With outstanding electrochemical performance and structural flexibility, the P2-Na0.67Co0.5Mn0.5O2 cathode material will promote the practical applications of sodium ion batteries.

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