| 钠锰比对NaxMnO2的性能和钠离子脱嵌过程的影响 |
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| 引用本文： | 谢永纯,王成,蒋芳,杨洋,苏静,龙云飞,文衍宣. 钠锰比对NaxMnO2的性能和钠离子脱嵌过程的影响[J]. 电化学, 2018, 24(4): 375. DOI: 10.13208/j.electrochem.180207 |
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| 作者姓名： | 谢永纯 王成 蒋芳 杨洋 苏静 龙云飞 文衍宣 |
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| 作者单位： | 广西大学化学化工学院;广西新型电池材料工程技术研究中心;广西有色金属及特色材料加工重点实验室;广西高校新能源材料及相关技术重点实验室 |
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| 基金项目： | 国家自然科学基金资助项目(No. 51564002)资助 |
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| 摘 要： | 采用高温固相法合成了NaxMnO2,并用X-射线衍射、X-射线光电子能谱、场发射扫描电镜、循环伏安、电化学阻抗谱和恒流充放电技术研究了钠锰比对材料的形态结构、电化学性能和钠离子脱嵌过程的影响. 结果表明,NaxMnO2 主要由Na0.7MnO2 和Na0.91MnO2 组成,且Na0.91MnO2 的量随着钠锰比的增加而增加. 随着钠锰比的增加,SEI 膜扩散、界面电化学反应和固相扩散的活化能先减少后增大,而材料的放电比容量则先增大后减少. 当钠锰比为0.80 时,合成的材料1C 倍率下首次放电比容量为152.8 mAh·g-1,50 次循环容量保持率为80.6%,5C 大倍率下放电比容量为88.3 mAh·g-1,表现出了良好的循环性能和倍率性,相应的SEI 膜扩散、界面电化学反应和固相扩散过程的活化能分别为68.23、40.07 和57.62 KJ·mol-1.
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| 关 键 词： | 钠离子电池 正极材料 NaxMnO2 钠离子脱嵌 |
| 收稿时间： | 2018-02-07 |
Influences of Na-Mn Ratio on Electrochemical Performances and Intercalation-Deintercalation Processes of Sodium Ion in NaxMnO2 |
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| Abstract: | In this work, NaxMnO2 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 preparedNaxMnO2 was mainly composed of Na0.7MnO2 and Na0.91MnO2, and the content of Na0.91MnO2 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. |
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| Keywords: | sodium-ion battery cathode NaxMnO2 sodium-ion intercalation/deintercalation |
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