18650型锂电池放电过程的瞬态热模型与电压模拟

Dynamic Thermal Modeling and Voltage Distribution Simulation for 18650-type Lithium-ion Battery Under Discharge Cycles

锂电池的热性能研究直接影响纯电动和混合动力汽车运行的安全性,目前多数锂电池单体的热模型仅能够预测稳态温度场,很难模拟和估计工作状态较长的瞬态温度场。本文针对18650型锂电池的电化学特性,建立单体电池在不同放电倍率工况下的瞬态温度模型,并进行电压分布模拟比较。充放电实验的电流倍率为1C恒流小电流和4C恒流大电流,在风冷方式下获得实验数据,提供单体电池热行为和瞬态温度场的基础数据,利用ANSYS CFD软件建立瞬态温度场的数学模型,并拟合电压分布曲线。实验结果表明,本文提出的瞬态热模型具有较高的估计精度,并得出随着充放电倍率增加单体电池表面温度的变化规律。

Study of thermal performance in lithium-ion battery cell is crucial which directly affects the vehicles safety.Most available thermal models for lithium-ion battery cell predicts only steady-state temperature field.This paper presents a mathematical model to predict the transient temperature and voltage distributions of 18650 lithium-ion battery at different discharge rates.In order to provide quantitative data regarding thermal behavior of lithium-ion batteries,the lithium-ion battery cell is tested inside the lab with an air-cooling method by four thermocouples mounted on the battery surface under constant current discharge rates of 1 C and 4 C.The experimental results show that the model predictions are in good agreement with experimental data for temperature and voltage profiles.The highest temperature is 46.86°C at 4 C discharge rate as obtained from simulation.The results also indicate the change rule of the battery surface temperature with the increased C-rates.