无机盐工业
主管:中海油天津化工研究设计院有限公司
主办:中海油天津化工研究设计院有限公司
   中海油炼油化工科学研究院(北京)有限公司
   中国化工学会无机酸碱盐专业委员会
ISSN 1006-4990 CN 12-1069/TQ

无机盐工业 ›› 2024, Vol. 56 ›› Issue (8): 67-73.doi: 10.19964/j.issn.1006-4990.2023-0520

• 研究与开发 • 上一篇    下一篇

铕掺杂改善锂离子电池正极材料LiFePO4电化学性能研究

薛山1,2(), 刘璐2, 戴建升2, 李晴2, 冯泽2, 李意能2()   

  1. 1.曲靖市德方纳米科技有限公司,云南 曲靖 655000
    2.深圳市德方纳米科技股份有限公司,广东 深圳 518000
  • 收稿日期:2023-11-02 出版日期:2024-08-10 发布日期:2024-09-26
  • 通讯作者: 李意能(1985— ),男,主要研究方向为锂离子电池正极材料的开发及应用;E-mail:liyineng@dynanonic.com
  • 作者简介:薛山(1993— ),男,博士,主要研究方向为锂离子电池正极材料的开发及应用;E-mail:shanxue1993@163.com
  • 基金资助:
    云南省科技厅科技计划项目(202103AA080009)

Study on electrochemical properties of europium⁃doped LiFePO4 cathode material for lithium⁃ion battery

XUE Shan1,2(), LIU Lu2, DAI Jiansheng2, LI Qing2, FENG Ze2, LI Yineng2()   

  1. 1.Qujing Dynanonic Co. ,Ltd. ,Qujing 655000,China
    2.Shenzhen Dynanonic Co. ,Ltd. ,Shenzhen 518000,China
  • Received:2023-11-02 Published:2024-08-10 Online:2024-09-26

摘要:

橄榄石结构的LiFePO4正极材料因其多重优势被广泛应用于新能源汽车和储能领域,但其较差的电导率和缓慢的锂离子扩散速率限制了其低温和倍率等性能。元素掺杂被认为是一种改善正极材料倍率、低温等性能的有效策略。采用固相法合成了稀土金属铕掺杂的LiFe1-x Eu x PO4/C正极材料,并研究了铕掺杂量对LiFePO4形貌、结构和电化学性能的影响。结果表明,铕掺杂能够改善LiFePO4/C的电化学性能,其中LiFe0.97Eu0.03PO4/C表现出最佳的倍率、低温和循环性能,其组成的纽扣电池在20C高倍率下放电比容量为95.1 mA·h/g(较LiFePO4/C提升57.7%),在低温(-20 ℃、0.1C)下的放电比容量为81.5 mA·h/g(较LiFePO4/C提升73.8%),1C下经200次循环后其容量保持率为96.43%(较LiFePO4/C高出2.46%)。X射线衍射分析和扫描电镜分析结果表明,铕的掺入能增大LiFePO4的晶胞体积,降低Li和O原子之间的结合能,从而提高锂离子的扩散速率。电化学交流阻抗测试结果表明,LiFe0.97Eu0.03PO4/C表现出最低的电荷转移电阻和最高的锂离子扩散系数,其锂离子扩散系数比未掺杂的LiFePO4/C高出2个数量级,这解释了其出色的倍率、低温和循环性能。

关键词: LiFePO4, 锂离子电池, 铕掺杂, 倍率性能, 循环性能

Abstract:

The olivine LiFePO4 cathode material is widely used in the field of electric vehicles and energy storage due to its multiple advantages,however,its low temperature and rate performance are limited by poor electrical conductivity and sluggish lithium ions diffusion kinetics.Elemental doping is considered to be an effective strategy to improve the properties of cathode materials such as multiplicity and low temperature performance.Here,rare earth metal europium⁃doped LiFe1-x Eu x PO4/C cathode materials were synthesized by solid⁃phase method,and the effects of europium doping on the morphology,structure,and electrochemical properties of LiFePO4 were investigated.The results showed that europium doping could improve the electrochemical properties of LiFePO4/C.The LiFe0.97Eu0.03PO4/C showed the best rate,low temperature and cycling performance,with its discharge capacity of 95.1 mA·h/g at high rate of 20C(57.7% enhancement compared with that of LiFePO4/C),discharge capacity of 81.5 mA·h/g(73.8% enhancement compared with that of LiFePO4/C) at low temperature of -20 ℃,and capacity retention rate of 96.43%(26.2% enhancement compared with that of LiFePO4/C) after 200 cycles at 1C.X-ray diffraction(XRD) and scanning electron microscopy(SEM) results showed that the europium doping could increase the cell volume of LiFePO4 and decrease the binding energy between Li and O atoms,which could improve the diffusion rate of lithium ions.Electrochemical alternating impedance(EIS) test results showed that LiFe0.97Eu0.03PO4/C exhibited the lowest charge transfer resistance,and the highest lithium ion diffusion coefficient that was two orders of magnitude higher than that of the undoped LiFePO4/C,which explained its excellent rate,low⁃temperature and cycling performance.

Key words: LiFePO4, lithium?ion batteries, europium doping, rate, cycling

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