高等学校化学学报 ›› 2022, Vol. 43 ›› Issue (2): 20210546.doi: 10.7503/cjcu20210546

• 物理化学 • 上一篇    下一篇

磷酸钐包覆对高电压镍锰酸锂正极材料电化学性能的影响

李晓辉1,3, 魏爱佳1,2,3(), 穆金萍1,2,3, 何蕊1,3, 张利辉1,3, 王军3, 刘振法1,3()   

  1. 1.河北省科学院能源研究所, 石家庄 050081
    2.河北工业大学化学工程与技术学院, 天津 300130
    3.河北省锂电池电解液用功能材料技术创新中心, 石家庄 050081
  • 收稿日期:2021-08-02 出版日期:2022-02-10 发布日期:2021-12-04
  • 通讯作者: 刘振法 E-mail:weiaijia2012@126.com;lzf63@sohu.com
  • 作者简介:魏爱佳, 女, 硕士, 助理研究员, 主要从事新能源材料与器件研究. E-mail: weiaijia2012@126.com
  • 基金资助:
    河北省科学院科技支撑项目(21709);河北省科技重大科技成果转化专项项目(20284401Z)

Effects of SmPO4 Coatingon Electrochemical Performance of High-voltage LiNi0.5Mn1.5O4 Cathode Materials

LI Xiaohui1,3, WEI Aijia1,2,3(), MU Jinping1,2,3, HE Rui1,3, ZHANG Lihui1,3, WANG Jun3, LIU Zhenfa1,3()   

  1. 1.Institute of Energy Resources,Hebei Academy of Sciences,Shijiazhuang 050081,China
    2.School of Chemical Engineering and Technology,Hebei University of Technology,Tianjin 300130,China
    3.Hebei Functional Materials Technology Innovation Center for Lithium Battery Electrolyte,Shijiazhuang 050081,China
  • Received:2021-08-02 Online:2022-02-10 Published:2021-12-04
  • Contact: LIU Zhenfa E-mail:weiaijia2012@126.com;lzf63@sohu.com
  • Supported by:
    the Project of Hebei Academy of Sciences, China(21709);the Hebei Province Major Scientific and Technological Achievements Transformation Project, China(20284401Z)

摘要:

尖晶石型镍锰酸锂(LiNi0.5Mn1.5O4)因制备成本低、 放电平台高及循环寿命长等优点, 越来越多地应用于大型储能设备、 能量转换设备、 动力汽车等领域. 然而LiNi0.5Mn1.5O4在高电压(5 V)充电状态下电解液易分解, 从而导致比容量降低以及循环性能衰退. 针对以上问题, 采用水热法制备磷酸钐(SmPO4)表面包覆改性LiNi0.5Mn1.5O4正极材料, 研究了SmPO4包覆量对LiNi0.5Mn1.5O4材料电化学性能的影响. 结果表明, 当SmPO4包覆量为0.5%(质量分数)时, 改性材料(LNMO@SP-0.5)的电化学性能最优, 在0.2C和5C倍率下的放电比容量分别为129.2和90.9 mA?h/g, 而未包覆的材料Pristine LNMO的放电比容量分别仅有114.2和77.7 mA?h/g. 在常温1C倍率下循环200次后, LNMO@SP-0.5的容量保持率为93.4%, 而Pristine LNMO的容量保持率仅为86.6%. 这归因于SmPO4包覆能够有效缓解LiNi0.5Mn1.5O4材料与电解液之间的副反应, 降低电极的极化程度和电荷转移电阻, 增加了Li+的扩散系数.

关键词: 尖晶石型镍锰酸锂, 正极材料, 磷酸钐包覆层, 水热法

Abstract:

Spinel-type LiNi0.5Mn1.5O4 has been widely used in large-scale energy storage equipment, energy conversion equipment and power vehicle, due to its low preparation cost, high discharge platform and long cycle life. However, the electrolyte of LiNi0.5Mn1.5O4 decomposes easily under high voltage(5 V) charging, which leads to a decrease in specific capacity and a decline in cycling performance. To solve the above problems, the LiNi0.5Mn1.5O4 cathode material was successfully coated with a thin layer of SmPO4via a hydrothermal process. The influence of the coating amount of SmPO4 on the electrochemical performance of LiNi0.5Mn1.5O4 material was systematically studied. The results indicate that the as-prepared LiNi0.5Mn1.5O4 coated with 0.5%(mass fraction) SmPO4(LNMO@SP-0.5) exhibits optimal electrochemical performance. In case of 0.2C and 5C, the discharge specific capacity of LNMO@SP-0.5 was 129.2and 90.9 mA?h/g, respectively, while Pristine LNMO only had 114.2 and 77.7 mA?h/g. LNMO@SP-0.5 exhibited a capacity retention of 93.4% after 500 cycles at 5C and 25 ℃, whereas the Pristine LNMO exhibited a poor capacity retention of 86.6%. The improvement was due to SmPO4 coating can effectively alleviate the side reaction between LiNi0.5Mn1.5O4 material and electrolyte, and reduce the polarization degree and charge transfer resistance of the electrode, and increase the diffusion coefficient of Li+.

Key words: Spinel-type LiNi0.5Mn1.5O4, Coathode material, SmPO4 Coating layer, Hydrothermal method

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