储能科学与技术 ›› 2024, Vol. 13 ›› Issue (1): 57-71.doi: 10.19799/j.cnki.2095-4239.2023.0213

• 高比能二次电池关键材料与先进表征专刊 • 上一篇    下一篇

高比能量锂离子软包电池针刺测试的影响因素研究

李召阳1(), 刘定宏1, 赵岩岩1, 陈满2, 雷旗开2, 彭鹏2, 刘磊1()   

  1. 1.中汽研汽车检验中心(常州)有限公司,江苏 常州 213000
    2.南方电网调峰调频发电 有限公司储能科研院,广东 广州 510000
  • 收稿日期:2023-04-10 修回日期:2023-06-30 出版日期:2024-01-05 发布日期:2024-01-22
  • 通讯作者: 刘磊 E-mail:lizhaoyang@catarc.ac.cn;liulei2013@catarc.ac.cn
  • 作者简介:李召阳(1993—),男,硕士,工程师,研究方向为锂电池测评技术,E-mail:lizhaoyang@catarc.ac.cn
  • 基金资助:
    常州市科技支撑计划(CE20220020┫基金项目:)

Nail penetration characteristics of high-energy-density lithium-ion pouch cell

Zhaoyang LI1(), Dinghong LIU1, Yanyan ZHAO1, Man CHEN2, Qikai LEI2, Peng PENG2, Lei LIU1()   

  1. 1.CATARC Automotive Test Center (Changzhou) Company Limited, Changzhou 213000, Jiangsu, China
    2.China Southern Power Grid Power Generation Co. Ltd. , Guangzhou 510000, Guangdong, China
  • Received:2023-04-10 Revised:2023-06-30 Online:2024-01-05 Published:2024-01-22
  • Contact: Lei LIU E-mail:lizhaoyang@catarc.ac.cn;liulei2013@catarc.ac.cn

摘要:

通过高重复性的针刺试验平台对两款高镍三元体系的高比能量(260~300 Wh/kg)软包锂离子动力电池进行试验,基于针刺内短路的电子流向模型,分析了不同针刺速度、针尖角度、夹具形式和针刺位置的影响和作用规律,并提出针刺安全性能的量化评估参数。试验结果表明:测试使用的夹具孔径越小、针刺速度越快,电池在针刺过程中的内短路放电就越严重,针刺后的温升和压降也越大,特别是使用20 mm以下孔径夹具对高比能软包电池进行高速针刺时有较大概率触发热失控并起火;然而由于软包电池的层间导热系数较低,此时电芯外部温升相对起火存在一定滞后性;在其他条件相同时,刺针针尖角度的变化并不会给内短路放电的能量损耗带来太大差异,反而是针刺位置的偏离会大大提高失效起火的风险,这再次印证了隔膜对刺针的包裹和阻隔作用是高比能量软包电池针刺起火与否的重要影响因素;区别于传统的测试现象描述和Hazard Level等级评价,针对内短路发热导致集流体熔融这一过程,可以根据其特征电压参数计算短路恶劣指数,能够为产品的针刺安全性能提供量化的评价指标。本研究有助于锂离子软包电池的针刺测评技术开发,并可以为高比能量电池在面临机械应力破坏或枝晶过度生长时的安全性提供试验参考。

关键词: 高能量密度, 锂离子电池, 针刺测试, 热失控

Abstract:

This study examines two types of high-energy-density lithium-ion pouch cells designed for electric vehicles using a highly repeatable test platform. Employing an electronic flow direction model for internal short circuits caused by nail penetration, we investigate the impact of various factors, including nail tip angles, fixture forms, penetration speed, and positions. In addition, we propose quantitative evaluation parameters for assessing the safety performance of nail penetration. The findings reveal that a smaller hole diameter in the fixture and faster penetration speed intensify the discharge during internal short circuits, leading to a rise in temperature and voltage drop. Notably, when a high-energy-density pouch cell is penetrated at high speed with a hole diameter below 20 mm, there is a higher probability of thermal runaway and fire. Despite the significant fire risk, the pouch cell's low interlayer thermal conductivity results in a delayed external temperature rise compared with the onset of fire. Moreover, altering the angle of the nail tip does not significantly affect the energy loss in internal short circuits under similar conditions. However, a deviation in the penetration position increases the risk of failure and fire, underscoring the impact of the separator's wrapping and blocking effect on the nail and subsequent fire in high-energy-density pouch cells. In contrast to the traditional description of test phenomena and hazard level evaluation, we introduce the short-circuit severity index. Calculated on the basis of characteristic voltage parameters in internal short circuits, this index serves as a quantitative evaluation metric for the safety performance of products. Our study contributes to the advancement of penetration evaluation technology for lithium-ion cells, offering valuable insights for enhancing the safety of high-energy-density cells when subjected to mechanical stress damage or dendrite overgrowth.

Key words: high-energy-density, lithium-ion battery, nail penetration, thermal runaway

中图分类号: