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汽车安全与节能学报

JASE ›› 2016, Vol. 07 ›› Issue (03): 313-321.DOI: 10.3969/j.issn.1674-8484.2016.03.010

• 汽车节能与环保 • 上一篇    下一篇

LMO 和 NMC 混合正极动力锂离子电池的衰减机理

刘宇隆1，娄忠良1，宋韶灵1，吴可1，吴宁宁1*，黄 俊2，张剑波2*，LIAW Bor yann3*   

  1. 1. 中信国安盟固利动力科技有限公司，北京 102200，中国；2. 清华大学 汽车工程系，北京100084，中国；
    3. 夏威夷大学马诺阿分校 海洋与土地科学技术学院，夏威夷自然能源研究中心，檀香山市，夏威夷96822，美国
  • 收稿日期:2015-10-29 出版日期:2016-09-25 发布日期:2016-09-30
  • 通讯作者: 张剑波(1967—)，男( 汉)，河南，教授。E-mail: jbzhang@mail.tsinghua.edu.cn
  • 作者简介:第一作者 / First author ： 刘宇隆(1989—)，男( 汉)，辽宁，工程师。E-mail: liuyulong@mgl.com.cn
  • 基金资助:

    汽车安全与节能国家重点实验室开放基金(KF14041)

Degradation mechanism of lithium-ion power battery with LMO + NMC blended positive electrode

LIU Yulong 1, LOU Zhongliang 1, SONG Shaoling 1, WU Ke 1, WU Ningning 1*, HUANG Jun 2,#br# ZHANG Jianbo 2*, LIAW Bor yann 3*,ZHANG Jianbo 2*, LIAW Bor yann 3*   

  1. 1. CITIC Guo'an MGL Power Science & Technology Co., Ltd., Beijing 10220, China; 2. Department of Automotive
    Engineering, Tsinghua University, Beijing 100084, China; 3. Hawaii Natural Energy Institute, School of Ocean and Earth
    Science and Technology, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA
  • Received:2015-10-29 Online:2016-09-25 Published:2016-09-30

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摘要：

实验并分析了石墨负极与LMO (LiMn2O4) 和 NMC (LiNi1/3Mn1/3Co1/3O2) 构成的混合正极体系全电池的衰减规律和机理。借助内置锂金属参比电极，通过测量在不同循环次数下全电池以及正负极的充放电曲线、直流内阻和交流阻抗谱，区分了正负极各自对全电池衰减的贡献。结果表明：1) 混合正极中，NMC 组分受可逆锂减少和石墨负极极化增大的共同影响，容量发挥受到限制，造成在循环后期混合正极的放电容量发挥逐渐变为由单一组分LMO 单独贡献；2) 循环过程中，全电池容量衰
减、阻抗增大，并且相比于正极，负极阻抗增大是全电池阻抗增大的主要原因。该结果可为改善石墨/混合正极体系的电池循环性能提供依据。

关键词: 电动汽车, 动力电池, 衰减机理, 混合正极, 参比电极, LMO (LiMn2O4) , NMC (LiNi1/3Mn1/3Co1/3O2)

Abstract:

The capacity degradation patterns and mechanisms of a cell comprising graphite negative electrodes and {LiMn2O4 (LMO) + LiNi1/3Mn1/3Co1/3O2 (NMC)} blended positive electrodes were investigated and analyzed. The contributions of positive and negative electrodes to the full cell degradation were distinguished by
measuring the charge/discharge curves, direct current resistance and electrochemical impedance spectroscopy, via embedded lithium metal reference electrode, as a function of cycle number during cycle aging. The results show that 1) In the blended positive electrodes, the lithiation of NMC was hindered by the progressive loss of lithium inventory as well as the growing graphite impedance. Gradually, LMO became the predominant capacity contributor in the blended positive electrodes in the later stage of cycle aging; 2) During cycle aging, the cell capacity faded along with the impedance increase largely at the negative electrode. These results provide evidence for improving the cycling performance of graphite/{LMO + NMC} cells.

Key words: electric vehicles, power batteries, degradation mechanism, blended positive electrodes, reference electrodes, LMO (LiMn2O4), NMC (LiNi1/3Mn1/3Co1/3O2)