高等学校化学学报 ›› 2019, Vol. 40 ›› Issue (6): 1280-1287.doi: 10.7503/cjcu20180694

• 物理化学 • 上一篇    下一篇

Na掺杂Li2-xNaxMnSiO4/C正极材料的微波辅助合成与电化学性能

马东玮, 田润赛, 刘振江, 冯源源, 丁泓宇, 冯季军()   

  1. 济南大学化学化工学院, 济南 250022
  • 收稿日期:2018-10-16 出版日期:2019-06-10 发布日期:2019-03-27
  • 作者简介:

    联系人简介: 冯季军, 女, 博士, 教授, 主要从事锂离子电池关键材料及电池工艺技术和新型储能系统及关键材料研究.E-mail: chm_fengjj@ujn.edu.cn

  • 基金资助:
    国家自然科学基金(批准号: 51102114)和济南市科技发展计划项目(批准号: 201401234)资助.

Microwave-assisted Synthesis and Electrochemical Performance of Na-Doped Cathode Materials Li2-xNaxMnSiO4/C

MA Dongwei, TIAN Runsai, LIU Zhenjiang, FENG Yuanyuan, DING Hongyu, FENG Jijun()   

  1. School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, China
  • Received:2018-10-16 Online:2019-06-10 Published:2019-03-27
  • Supported by:
    † Supported by the National Natural Science Foundation of China(No.51102114) and the Sci-Tech Development Project of Jinan, China(No.201401234).

摘要:

采用溶胶-凝胶法并辅以微波热处理合成了Na掺杂改性的Li2-xNaxMnSiO4/C(x=0, 0.05, 0.09, 0.13)复合正极材料. 利用X射线衍射(XRD)、 扫描电子显微镜(SEM)、 恒电流充放电测试、 循环伏安(CV)和交流阻抗(EIS)测试等对材料进行了表征. 结果表明, 经微波辐射后得到的电极材料具有Pmn21型空间结构, 其碳层分布均匀, 粒径细小均匀, 约为15~30 nm. 在微波辅助原位碳包覆和Na掺杂共同作用下, 复合材料的电荷转移电阻明显降低, Li+扩散速率增大, 展现出优良的电化学性能. 在0.1C倍率下Li1.91Na0.09MnSiO4/C样品首次放电比容量为211 mA∙h/g, 50次循环后仍保持80 mA∙h/g的可逆容量; 0.5C和2.0C倍率下的放电比容量分别为106和53 mA∙h/g, 大电流下的可逆容量明显提高.

关键词: 正极材料, Li2MnSiO4, 微波辅助合成, 原位碳包覆, 钠掺杂

Abstract:

Li2-xNaxMnSiO4/C(x=0, 0.05, 0.09, 0.13) composite cathode materials were synthesized with microwave assisted sol-gel method. The crystal structure, morphology and electrochemical performance were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), galvanostatic charge-discharge test, cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS). The results indicate that the as-prepared materials can be well indexed to Pmn21 space group. The particles are fine with carbon layer coated uniformity and their size are evenly distributed in the range of 15—30 nm. With the synergistic effects of Na+ doping and microwave assisted in-situ carbon coating, the charge transfer resistance is reduced while the diffusion of Li+ is enhanced significantly, leading to excellent electrochemical performance. The Li1.91Na0.09MnSiO4/C exhibits an initial discharge capacity as high as 211 mA∙h/g at 0.1C and retained 80 mA∙h/g after 50 cycles. The reversible capacities at high rate currents are also improved obviously, with discharge capacities of 106 mA∙h/g and 53 mA∙h/g at 0.5C and 2.0C separately.

Key words: Cathode material, Li2MnSiO4, Microwave assisted synthesis, in-situ carbon coating, Na-doping

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