Chin. Phys. Lett.  2018, Vol.35 Issue (4): 048801  DOI:10.1088/0256-307X/35/4/048801
A High-Temperature $\beta$-Phase NaMnO$_{2}$ Stabilized by Cu Doping and Its Na Storage Properties
1Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 1001902School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049>

### Abstract

The high-temperature $\beta$-phase NaMnO$_{2}$ is a promising material for Na-ion batteries (NIBs) due to its high capacity and abundant resources. However, the synthesis of phase-pure $\beta$-NaMnO$_{2}$ is burdensome and cost-ineffective because it needs to be sintered under oxygen atmosphere at high temperature and followed by a quenching procedure. Here we first report that the pure $\beta$ phase can be stabilized by Cu-doping and easily synthesized by replacing a proportion of Mn with Cu via a simplified process including sintering in air and cooling to room temperature naturally. Based on the first-principle calculations, the band gap decreases from 0.7 eV to 0.3 eV, which indicates that the electronic conductivity can be improved by Cu-doping. The designed $\beta$-NaCu$_{0.1}$Mn$_{0.9}$O$_{2}$ is applied as cathode in NIBs, exhibiting an energy density of 419 Wh/kg and better performance in terms of rate capability and cycling stability than those in the undoped case.

### 基金资助

Supported by the National Key Technologies R&D Program of China under Grant No 2016YFB0901500, and the National Nature Science Foundation of China under Grant Nos 51725206 and 51421002.

### 引用本文

[英文]
Li-Wei Jiang, Ya-Xiang Lu, Yue-Sheng Wang, Li-Lu Liu, Xing-Guo Qi, Cheng-Long Zhao, Li-Quan Chen, Yong-Sheng Hu. A High-Temperature $\beta$-Phase NaMnO$_{2}$ Stabilized by Cu Doping and Its Na Storage Properties[J]. CPL, 2018, 35(4): 048801.

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