物理化学学报 >> 2017, Vol. 33 >> Issue (8): 1605-1613.doi: 10.3866/PKU.WHXB201704145

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LiFePO4包覆的Li1.2Mn0.54Ni0.13Co0.13O2锂离子电池正极材料:增强的库伦效率和循环性能

何磊.1,徐俊敏.1,2,*(),王永建.1,张昌锦.1,3,*()   

  1. 1 中国科学院强磁场科学中心,合肥230031
    2 郑州大学物理工程学院,材料物理教育部重点实验室,郑州450052
    3 南京大学人工微结构科学与技术协同创新中心,南京210093
  • 收稿日期:2017-03-02 发布日期:2017-06-14
  • 通讯作者: 徐俊敏.,张昌锦. E-mail:junminxu@zzu.edu.cn;zhangcj@hmfl.ac.cn
  • 基金资助:
    中国科学院合肥科学中心科学研究项目(2015SRG-HSC025);和国家自然科学基金(U1532267);和国家自然科学基金(U11504379)

LiFePO4-Coated Li1.2Mn0.54Ni0.13Co0.13O2 as Cathode Materials with High Coulombic Efficiency and Improved Cyclability for Li-Ion Batteries

Lei. HE1,Jun-Min. XU1,2,*(),Yong-Jian. WANG1,Chang-Jin. ZHANG1,3,*()   

  1. 1 High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, P. R. China
    2 School of Physical Engineering, Key Laboratory of Material Physics of Ministry of Education of China, Zhengzhou University, Zhengzhou 450052, P. R. China
    3 Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, P. R. China
  • Received:2017-03-02 Published:2017-06-14
  • Contact: Jun-Min. XU,Chang-Jin. ZHANG E-mail:junminxu@zzu.edu.cn;zhangcj@hmfl.ac.cn
  • Supported by:
    The project was supported by the Scientific Research Grant of Hefei Science Center of Chinese Academy of Sciences(2015SRG-HSC025);and National Natural Science Foundation of China(U1532267);and National Natural Science Foundation of China(U11504379)

摘要:

采用简单水溶液法制备LiFePO4包覆的Li1.2Mn0.54Ni0.13Co0.13O2富锂正极材料,包覆后的材料分别经过400℃或500℃煅烧处理5 h。测试结果显示,400℃煅烧处理的包覆样品在0.1 C(1 C=300 mA·g-1)电流密度下充放电时,首次库仑效率可以高达91.9%,同时,首次放电比容量可达到295.0 mAh·g-1。此外,该包覆样品还具有良好的循环性能,在1 C电流密度下循环100次放电比容量仍可保持在206.7 mAh·g-1。进一步的研究发现LiFePO4的包覆不仅可以提高Li1.2Mn0.54Ni0.13Co0.13O2富锂材料的首次库仑效率和循环稳定性能,而且还能够有效抑制材料在充放电过程中的电压衰减。上述电化学性能的有效提升主要归因于LiFePO4包覆层可以阻碍Li1.2Mn0.54Ni0.13Co0.13O2富锂材料与电解液之间的直接接触,减少副反应的发生,增强材料表面的结构稳定性,同时还可以为富锂材料提供额外的可逆容量。

关键词: 锂离子电池, 富锂正极材料, 磷酸铁锂包覆, 高库仑效率, 循环性能

Abstract:

In this work, we present a new design for a surface protective layer formed by a facile aqueous solution process in which a nano-architectured layer of LiFePO4 is grown on a Li-rich cathode material, Li1.2Mn0.54Ni0.13Co0.13O2. The coated samples are then calcined at 400 or 500℃ for 5 h. The sample after calcination at 400℃ demonstrates a high initial columbic efficiency of 91.9%, a large reversible capacity of 295.0 mAh·g-1 at 0.1 C (1 C=300 mA·g-1), and excellent cyclability with a capacity of 206.7 mAh·g-1after 100 cycles at 1 C. Meanwhile, voltage fading of the coated sample is effectively suppressed by protection offered by a LiFePO4 coating layer. These superior electrochemical performances are attributed to the coating layer, which not only protects the Li-rich cathode material from side reaction with the electrolyte and maintains the stability of the interface structure, but also provides excess reversible capacity.

Key words: Lithium-ion battery, Lithium-rich cathode materials, LiFePO4 coating, High Columbic efficiency, Cyclability

MSC2000: 

  • O646