基于三维电化学热耦合析锂模型的锂离子电池参数设计

Parameter design of lithium-ion batteries based on a three-dimensional electrochemical thermal coupling lithium precipitation model

锂离子电池负极析锂可能会诱发热失控,进而导致安全事故。而通过优化电池设计参数能够有效减少析锂副反应的发生,因此本工作提出一种基于三维电化学热耦合析锂模型的锂离子电池参数设计优化方法。首先,将模型参数进行分类,分别采用实验、精确测量、文献查找和参数辨识等方法获取相应的参数。同时加入可逆锂重嵌入机制和产热模型,建立三维电化学热耦合析锂模型。模型建立完成后,对模型精度进行验证,验证结果表明模型可以较好地模拟电池在常温和低温下端电压的变化,并且能够定量描述在低温大倍率充电期间电池内部的析锂程度、温度分布等非均一现象。最后,通过分析电极尺寸和极耳位置,研究电池设计参数对非均一析锂的影响。仿真结果表明:电极长度增加会导致电极区域温度差异和电流密度的不一致性增大,综合影响下使电池析锂时间略有提前,但对电池总体析锂程度影响较小;电池极耳位置处于长度方向的轴线对侧时能够有效缓解负极析锂,相对析锂程度降低了16.7%。

Lithium deposition on the negative electrode of lithium-ion batteries may induce thermal runaway that can lead to safety accidents.The occurrence of lithium precipitation side reactions can be reduced effectively by optimizing the battery design parameters.Therefore,this study proposes a parameter design optimization method for lithium-ion batteries based on a three-dimensional electrochemical,thermal coupled lithium precipitation model.First,the model parameters were classified,and the corresponding parameters were obtained using experiments,exact measurements,literature searches,and parameter identification,respectively.The reversible lithium re-embedding mechanism and heat production model were added to establish a three-dimensional electrochemical,thermal coupling lithium precipitation model.After constructing the model,the accuracy of the model was verified.The verification results showed that the model could simulate the changes in the terminal voltage of the battery at room temperature and low temperature and could quantitatively describe the nonhomogeneous phenomena,such as the degree of lithium precipitation and temperature distribution inside the battery during low temperature large rate charging.Finally,the effects of the battery design parameters on nonhomogeneous lithium precipitation were investigated by analyzing the electrode size and lug position.The simulation results showed that increasing the electrode length would increase the temperature difference in the electrode area and the inconsistency of the current density.The combined effect would advance the lithium precipitation time of the battery slightly,but the effect on the overall degree of lithium precipitation of the battery was relatively small.When the position of the battery tab was on the opposite side of the axis in the longitudinal direction,it could effectively alleviate lithium deposition on the negative electrode,and the relative lithium precipitation degree was reduced by 16.7%.