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三元软包锂离子电池放电过程扩散诱导应力与热应力对比研究

A comparative study on diffusion-induced stress and thermal stress during discharge of ternary soft pack lithium-ion battery
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摘要 为了明晰锂离子电池在放电过程中产生的扩散诱导应力和热应力对电池的影响,使用Comsol Multiphysics 6.0建立了18.5 Ah软包NCM111锂离子电池的电化学-力-热耦合模型,基于该模型对不同放电倍率下电池的负极颗粒中心表面锂浓度差、扩散诱导应力、热应力及膨胀行为进行了仿真分析。扩散诱导应力可通过一维电化学模型及其衍生的颗粒维度进行仿真分析,而热应力则需要通过三维固体力学和传热模型进行仿真。研究结果表明,随着放电倍率的增加,电池产生的扩散诱导应力和热应力都会增大,因此,低放电倍率有助于降低电池产生的应力。负极颗粒产生的扩散诱导应力与颗粒中心表面锂浓度差相关,颗粒中心与表面的锂浓度差随着放电过程的进行逐渐增大。将一维模型中的负极视为由无数负极颗粒组成的线段,放电前期,靠近隔膜端的颗粒中心与表面锂浓度差高于集流体端,放电后期则相反,这个变化发生的转折点在放电深度为60%~70%之间。这也意味着放电前期隔膜端的负极颗粒产生的扩散诱导应力大于集流体端的负极颗粒,也更容易破裂,而放电后期则相反。负极颗粒产生的扩散诱导应力大小为兆帕级,远高于电芯产生的大小为千帕级的热应力。同时,电芯产生的热应力和最大位移与电池温差呈线性关系,随着放电倍率的增加而增大。值得注意的是,与圆柱形电池不同,软包电池的极耳与电芯连接处会产生较大的热应力。本研究对比分析了软包NCM111锂离子电池放电过程产生的扩散诱导应力与热应力,为电极和电芯的制造及应力监测提供理论支撑。 This study investigates the effects of diffusion-induced stress and thermal stress on lithium-ion batteries during discharge by establishing an electrochemical-mechanical-thermal coupling model for an 18.5 Ah soft-package NCM111 lithium-ion battery using Comsol Multiphysics 6.0.The analysis encompasses the lithium concentration difference between the centers and surfaces of anode particles,diffusion-induced stress,thermal stress,and expansion behavior at different discharge rates.Diffusion-induced stress is simulated using a one-dimensional electrochemical model and its derivative particle dimension,while thermal stress is addressed through a three-dimensional solid mechanics and heat transfer model.The findings indicate that both diffusion-induced and thermal stresses escalate with an increase in discharge rate,and a lower discharge rate mitigates the stress experienced by the battery.Specifically,diffusion-induced stress in the anode particles correlates with the lithium concentration difference between the centers and surfaces of these particles,intensifying progressively during discharge.In the pre-discharge phase,this concentration difference is higher near the separator than near the collector,with the situation reversing post-discharge.A critical turning point occurs at a depth of discharge(DOD)of 60%-70%,suggesting a similar trend for diffusion-induced stresses.Notably,the diffusion-induced stress in the anode particles reaches the order of MPa,substantially exceeding the thermal stress in the cell,which is on the order of kPa.Furthermore,the maximum thermal stress and displacement in the cell exhibit a linear relationship with the cell's temperature difference,escalating with discharge rate.A distinctive observation is the significant thermal stress at the connection points between the tabs and the cell in soft-pack batteries,in contrast to cylindrical batteries.This comparative analysis of diffusion-induced and thermal stresses during the discharge of ternary soft-pack NCM111 lithium-ion batteries aims
作者 王瑞梓 刘训良 豆瑞锋 周文宁 方娟 WANG Ruizi;LIU Xunliang;DOU Ruifeng;ZHOU Wenning;FANG Juan(School of Energy an Environmental Engineering,University of Science and Technology Beijing;Multi-mode Industrial Energy Storage Technology R&D Center,University of Science and Technology Beijing,Beijing 100083,China)
出处 《储能科学与技术》 CAS CSCD 北大核心 2024年第4期1128-1141,共14页 Energy Storage Science and Technology
基金 国家自然科学基金项目(52076012)。
关键词 三元软包锂电池 多物理场耦合模型 扩散诱导应力 热应力 ternary soft pack lithium-ion battery multiphysics coupling model diffusioninduced stress thermal stress
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