锂离子电池多物理场耦合模型中的粒径分析

Particle Size Analysis in A Coupled Multi-Physics Models for Lithium-Ion Batteries

为深入理解锂离子电池(Lithium-Ion Battery,LIB)内部的多物理场耦合行为,更好地为锂离子电池的生产制造及优化等工作提供参考,文中通过数值模拟方式,在有限元仿真软件COMSOL Multiphysics中建立了更符合物理实际的锂离子电池电化学-热-力(Electrochemical-Thermal-Mechanical,ETM)耦合模型,并进行求解。该模型考虑了电池工作时电极与颗粒两个尺度中的应力生成,解决了以往模型中电极层面应力难以计算的问题。同时通过考虑应力对锂离子扩散及过电位的修正,更好地关联了应力与电化学间的关系。基于该模型,文中讨论了不同正极粒径对电池性能的影响。数值结果表明,当正极粒径小时,锂离子电池放电过程中各物理场的性能指标较好,电池能量密度增大,证明采用较小的正极粒径可提升锂离子电池性能。

In order to deeply understand the multi-physical field coupling behavior inside the LIB(Lithium-Ion Battery)and better provide reference for the manufacturing and optimization design of the LIB,a more physically realistic coupled ETM(Electrochemical-Thermal-Mechanical)model of the LIB is established and solved in the finite element simulation software COMSOL Multiphysics by means of numerical simulation in the present study.The model takes into account the stress generation in both electrode and particle scales during battery operation,which solves the problem of difficult calculation of stress at the electrode level in previous models,and better correlates the relationship between stress and electrochemistry by considering the correction of stress on lithium diffusion and overpotential.Based on this model,the effect of different positive electrode particle sizes on the battery performance is discussed in the study.The numerical results show that the performance index of each physical field during the discharge of LIB is better and the energy density of the battery is improved when the positive electrode particle size is small,which proves that the use of smaller positive electrode particle size can improve the performance of LIB.