锂离子电池不可逆膨胀模型及应用

Irreversible Expansion Model for Lithium-Ion Batteries and its Application

针对锂离子电池多次充放电循环后容量衰减量的快速估算问题,文中基于锂离子电池(Lithium-Ion Battery,LIB)容量衰减模型提出了一种利用电池外部膨胀位移快速估算其内部容量衰减的方法。在锂离子电池容量衰减模型的基础上推导其径向不可逆膨胀模型,通过COMSOL Multiphysics对圆柱形锂离子电池Sanyo UR18650E进行建模和求解,并对比数值结果与实验数据,从而对所提模型进行验证。基于上述模型,分析了电池在充放电循环过程中由于副反应参与而造成的容量衰减和不可逆膨胀行为的原因。结果表明,副反应速率变化造成了副反应产物浓度在负极的梯度分布,副反应产物堆积使电池膨胀位移随循环线性增长。文中还利用副反应产物作为桥梁得到电池容量衰减与其径向位移的函数计算式,为容量衰减量的快速估算提供了新方法。

In view of the problem of rapid estimation of capacity attenuation after multiple charge and discharge cycles of LIB(lithium-ion battery),a new method based on the capacity attenuation model of lithium-ion battery is proposed to rapidly estimate its internal capacity attenuation using the external expansion displacement of the battery.Based on the capacity attenuation model of LIB,the radial irreversible expansion model is derived,and the cylindrical LIB Sanyo UR18650E is modeled and solved by COMSOL Multiphysics,and the numerical results are compared with the experimental data,so as to verify the proposed model.Based on the above model,the causes of capacity attenuation and irreversible expansion of battery due to side reactions during the charge-discharge cycle are analyzed.The results show that the change of side reaction rate causes the gradient distribution of the concentration of side reaction products in the negative electrode,and the accumulation of side reaction products causes the expansion displacement of the battery to increase linearly with the cycle.The function formula of the cell capacity attenuation and its radial displacement is obtained by using the side reaction product as a bridge,which provides a new method for the rapid estimation of the capacity attenuation.