锂电池温度分析及内部结构散热优化

TEMPERATURE ANALYSIS OF LITHIUM BATTERY AND HEAT DISSIPATION OPTIMIZATION OF ITS INTERNAL STRUCTURE

储能技术的引入有效提高了可再生能源发电接入电力系统的效率与安全稳定性,但目前在电力系统的储能系统中广泛使用的锂电池存在的热失控问题还有待进一步解决。对特定型号的锂电池进行了在室温、无散热条件下,充电倍率为0.2 C,放电倍率分别为0.2、0.3、0.4和0.5 C时的充放电温升实验,并得到了相应的实验数据。建立上述锂电池的热效应三维模型后,根据实验数据来确定仿真模拟中对应的热物性参数;随后通过ANSYS仿真软件模拟改变电池组内部单体电芯的截面形状,探究可改善锂电池工作温度的内部结构形式。仿真结果表明,保持电池组内部单体电芯的截面积基本不变和长度不变,将截面形状由矩形改为正方形,并维持单体电芯的数量和间隙、外表面铝合金外壳厚度、环境温度、各项散热系数和电池的生热速率不变,此时由于电池组内部流道空间增大,会相应增大电池组内部的对流传热效果,从而带走更多热量。因此相较于矩形截面的锂电池热效应模型,正方形截面的锂电池热效应模型在由表面积减小而引起的整体散热量降低的情况下,在相同放电倍率时引起的温升更小,可优化锂电池的工作温度。

Energy storage technology can effectively improve the power system efficiency,safety and stability,when renewable energy power generation connected to power system.The problem of thermal runaway in lithium batteries which are widely used in energy storage system of power system,needs to be further resolved.In this paper,the temperature rise experiment of specific type of lithium battery during charging and discharging was carried out,at room temperature without heat dissipation,with charge rate of 0.2 C,discharge rate of 0.2,0.3,0.4,and 0.5 C.The corresponding experimental data were obtained.After the thermal effect 3D model of the corresponding lithium battery is established,the corresponding thermophysical parameters in the simulation are determined according to the experimental data.Changing the cross-section shape of the single cell in the battery pack by ANSYS software,to explore the internal structure which can improve the working temperature of the lithium battery.In the case of a fixed cross-sectional area and length of the internal single cell in battery pack,the number of single cell and the gap,the thickness of the outer surface aluminum alloy shell,the ambient temperature,the heat dissipation coefficient and the heat generation rate of the battery,the simulation results show that the cross-section shape is determined by if a square replaces a rectangle,the flow channel space inside the battery pack will increase,which will increase the convective heat transfer effect inside the battery pack to take away more heat.Therefore,the overall heat dissipation of the thermal effect model of lithium battery with a square cross-section is reduced,and a smaller temperature rise can be obtained at the same discharge rate,which can optimize the working temperature of the lithium battery.