Influences of Na-Mn Ratio on Electrochemical Performances and Intercalation-Deintercalation Processes of Sodium Ion in Na_xMnO₂

Authors

Yong-chun XIE, 1. School of Chemistry of and Chemical Engineering, Guangxi University, Nanning 530004, China;
Cheng WANG, 1. School of Chemistry of and Chemical Engineering, Guangxi University, Nanning 530004, China;
Fang JIANG, 1. School of Chemistry of and Chemical Engineering, Guangxi University, Nanning 530004, China;
Yang YANG, 1. School of Chemistry of and Chemical Engineering, Guangxi University, Nanning 530004, China;
Jing SU, 1. School of Chemistry of and Chemical Engineering, Guangxi University, Nanning 530004, China;Guangxi Novel Battery Materials Research Center of Engineering Technology, Nanning 530004, China;Guangxi Colleges and Universities Key Laboratory of Novel Energy Materials and Related Technology, Nanning 530004, China
Yun-fei LONG, 1. School of Chemistry of and Chemical Engineering, Guangxi University, Nanning 530004, China;
Yan-xuan WEN, 1. School of Chemistry of and Chemical Engineering, Guangxi University, Nanning 530004, China;Guangxi Key Laboratory of Processing for Non-ferrous Metallic and Featured Materials, Guangxi University, Nanning 530004, China;Guangxi Novel Battery Materials Research Center of Engineering Technology, Nanning 530004, China;Guangxi Colleges and Universities Key Laboratory of Novel Energy Materials and Related Technology, Nanning 530004, ChinaFollow

Corresponding Author

Yan-xuan WEN(wenyanxuan@vip.163.com)

Abstract

In this work, Na_xMnO₂ was synthesized by a solid-state reaction. The influences of Na:Mn ratio on the structure, morphology and electrochemical performance, and sodium ion intercalation/deintercalation processes were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge test. The prepared Na_xMnO₂ was mainly composed of Na_0.7MnO₂ and Na_0.91MnO₂, and the content of Na_0.91MnO₂ increased with the increase of Na:Mn ratio. However, the activation energy values of surface membrane diffusion, interfacial electrochemical reaction and Na⁺ diffusion in the bulk material first decreased and then increased with the increase of Na:Mn ratio, while the discharge capability first increasedand then decreased with the increase of Na:Mn ratio. The sample synthesized with the Na:Mn ratio of 0.80 delivered a discharge capacity of 152.8 mAh·g^-1 with a capacity retention of 80.6% after 50 cycles at 1C. Even being charged/discharged at 5C, this sample still provided a discharge capacity of 88.3 mAh·g^-1, showing good cycle-stability and rate performance. The activation energy values of surface membrane diffusion, interfacial electrochemical reaction and solid-phase diffusion were found to be 68.23, 40.07 and 57.62 kJ·mol^-1, respectively.

Graphical Abstract

Keywords

sodium-ion battery, cathode, NaxMnO2, sodium-ion intercalation/deintercalation

DOI Link

https://doi.org/10.13208/j.electrochem.180207

Publication Date

2018-08-28

Online Available Date

2018-04-25

Revised Date

2018-03-26

Received Date

2018-02-07

Recommended Citation

Yong-chun XIE, Cheng WANG, Fang JIANG, Yang YANG, Jing SU, Yun-fei LONG, Yan-xuan WEN. Influences of Na-Mn Ratio on Electrochemical Performances and Intercalation-Deintercalation Processes of Sodium Ion in Na_xMnO₂[J]. Journal of Electrochemistry, 2018 , 24(4): 375-384.
DOI: 10.13208/j.electrochem.180207
Available at: https://jelectrochem.xmu.edu.cn/journal/vol24/iss4/9