储能科学与技术 ›› 2017, Vol. 6 ›› Issue (4): 770-775.doi: 10.12028/j.issn.2095-4239.2017.0004

• 研究开发 • 上一篇    下一篇

高镍三元锂离子电池高温存储性能衰退机理

王嗣慧，徐中领，杜  锐，孟焕平，刘  永，柳  娜，梁成都   

  1. 宁德时代新能源科技股份有限公司，福建 宁德 352106
  • 收稿日期:2017-01-12 修回日期:2017-03-27 出版日期:2017-07-01 发布日期:2017-07-01
  • 通讯作者: 柳娜，博士，从事锂离子电池相关材料的应用研究，E-mail：liun@catlbattery.com。
  • 作者简介:王嗣慧（1986—），女，博士，从事锂离子电池正极材料研究，E-mail：wangsih@catlbattery.com

Degradation study of Ni-rich NCM batteries operated at high tempertures

WANG Sihui, XU Zhongling, DU Rui, MENG Huanping, LIU Yong, LIU Na, LIANG Chengdu   

  1. Contemporary Amperex Technology Ltd., Ningde 352106, Fujian, China
  • Received:2017-01-12 Revised:2017-03-27 Online:2017-07-01 Published:2017-07-01

PDF

3062

被引次数

6

摘要： 随着动力电池市场对长续航里程需求的不断提升，高能量密度的高镍三元材料已逐渐成为动力电池正极材料的开发热点之一。动力电池使用寿命一般要求10年以上，考虑到产品开发的时效性，目前一般采用加速寿命试验的方法来评估动力电池的长期使用寿命。本工作以共沉淀-高温烧结法自主合成的高镍NCM811材料为研究体系，将NCM811/石墨软包电池在60 ℃满充条件下进行存储实验，电池的高温存储寿命约为180天；采用XRD、SEM、ICP-AES、XPS和HRTEM等方法对存储前（BOL）和存储后（EOL）的极片进行表征，研究结果表明高镍材料电池高温存储失效主要与以下因素有关：存储后高镍三元材料表面副产物累积，材料表面岩盐相增加，导致电池阻抗增加；溶出的过渡金属元素在负极石墨上沉积，破坏负极表面的SEI，从而加速了活性锂的消耗。对材料进行有效的表面包覆或体相掺杂是改善高镍三元材料高温存储性能的关键.

关键词: 高镍材料, 高温存储, 衰退机理

Abstract: Driven by increasing demand for long range of electric vehicles, Ni-rich cathode materials have attracted lots of attention for the development of high energy density EV batteries. As the life span of EV batteries needs to be more than 10 years and the product development time is limited, an accelerated life span testing is often used to assess the long-term performance of the batteries. In this work, we prepared NCM811 cathode material through co-precipitation and high-temperature calcination and stored NCM811/Graphite pouch-type full cells at 60 ℃ in a fully charged state for the investigation of their storage performance. It was found that the storage capacity of the cells decreased to 80% after 180-day storage. XRD, SEM, ICP-AES, XPS and HRTEM techniques were used to investigate the differences between freshly made and the degraded electrodes. The results demonstrated the formation of by-products on the surface of cathode, and cathode materials exhibited layered-spinel-rock salt phase transformation after storage, both greatly increased the cell impedance. In addition, transition metal ions dissolved from the cathode were found to accumulate on the anode, which may have destroyed the SEI, leading to the consumption of the active lithium. Surface coating and bulk doping could resolve the problem through stabilizing the surface and bulk structure of the cathode materials.

Key words: Ni-rich cathode, high temperature storage, failure mechanism