储能科学与技术

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储能电池模组膨胀力特性研究及仿真分析

樊慧敏1(), 彭浩鸿1, 孟辉1, 唐梦宏1, 易昊昊1, 丁静1, 刘金成1, 徐成善2, 冯旭宁2   

  1. 1.惠州亿纬锂能股份有限公司,广东 惠州 516000
    2.清华大学,北京 100084
  • 收稿日期:2021-11-30 修回日期:2021-11-30
  • 通讯作者: 樊慧敏 E-mail:115279@evebattery.com
  • 作者简介:樊慧敏(1994—),女,博士,研究方向为储能电池在系统的应用,E-mail:115279@evebattery.com

The Research and Simulation Analysis of Swelling Force Characteristics in Energy Storage Battery Modules

Huimin FAN1(), Haohong PENG1, Hui MENG1, Menghong TANG1, Haohao YI1, Jing DING1, Jincheng LIU1, Chengshan XU2, Xuning FENG2   

  1. 1.EVE Energy Co. , Huizhou 516006, Guangdong, China
    2.School of Vehicle and Mobility, Tsinghua University, Beijing 100084, China
  • Received:2021-11-30 Revised:2021-11-30
  • Contact: Huimin FAN E-mail:115279@evebattery.com

摘要:

锂离子电池在充放电过程中存在膨胀力,其受电池的荷电状态(State of Charge, SOC)和健康状态(State of Health, SOH)影响。对于储能磷酸铁锂电池,其膨胀力特性是有关储能电池系统电性能及安全性能的重要特性之一, 而大容量储能磷酸铁锂电池在全生命周期内膨胀力的演变特性及机理尚不清晰。本工作选择一款容量为280安时的磷酸铁锂电池为研究对象,将其组装成不同串数的模组,采用膨胀力夹具模拟其在实际储能模组中的应用场景,开展了循环耐久性测试,并对全SOC及全生命周期下电池模组膨胀力的演变规律进行了分析。研究结果显示:由于石墨和磷酸铁锂材料的结构特性,充电过程在~30%SOC和100%SOC有2次膨胀力峰值,放电过程也在100%SOC和30%SOC有2次膨胀力峰值。各膨胀力峰值随着电池的衰减呈现不同的演变规律,100%SOC时的膨胀力由最大值逐渐演变成最小值,30%SOC时的膨胀力演变成最大值。此外,在SOH衰减至约90%后,模组膨胀力与SOH呈线性相关,且电芯串联数量的增加没有改变模组最大膨胀力的增长趋势,1P12S模组的最大膨胀力在70%SOH时达到了2365kgf。根据实测数据对模组的膨胀力仿真分析表明,模组主要零部件的设计能够满足全生命周期内的结构安全性能。该工作初步探究了磷酸铁锂电池模组的膨胀力特性,有助于为模组层级的膨胀力仿真和预测提供参考,为后期磷酸铁锂电池在储能系统模组的安全设计开发提供了支撑。

关键词: 磷酸铁锂电池, 膨胀力, 储能模组, SOC, SOH

Abstract:

The swelling force characteristic is one of the important characteristics for studying the performance and safety of energy storage LiFePO4 batteries, which is affected by the state of charge (SOC) and state of health (SOH) of the battery. However,evolution and mechanisms of swelling force over the full life cycle of large-capacity LiFePO4 batteries are not well understood now. In this study, we investigate the variation of swelling force of 280Ah LiFePO4 battery in a special fixture, which was assembled into modules with different string numbers, and we analyze the evolution of swelling force under the full-SOC and the full-life cycle. The results show that the swelling force changes with the SOC during a single cycle. Due to the structural characteristics of graphite and lithium iron phosphate materials, there were two swelling peaks during the charging process at approximately 30% SOC and 100% SOC, and two peaks during the discharging process at 100% SOC and 30% SOC. These peaks evolved differently as the battery degraded. The force at 100%SOC gradually changes from the maximum value to the minimum value, while at 30%SOC, the force gradually becomes the largest. In addition, after the SOH dropped to around 90%, the expansion force showed a linear correlation with SOH. The swelling force growth trend maintained as increase the series number, the maximum expansion force of the 1P12S module reached 2365 kgf when the SOH was 70%. Based on the measured data, the simulation analysis of the swelling force of the module indicates that the design of the module's main components can meet the structural safety performance requirements throughout its entire lifecycle. This work preliminarily explores the swelling force characteristics of LFP battery modules, which is conducive to providing reference for swelling force simulation at the module level. It provides support for the safe design and development of LFP battery modules in energy storage system.

Key words: LFP battery, swelling force, energy storage module, State of Charge (SOC), State of Health (SOH)

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