The Thermal Analysis Of Power Li-ion Batteries

Under the age requirement of low carbon environmental protection, the Electric Vehicle(EV) emerges as a kind of new energy vehicles, meanwhile, Li-ion battery, as the most promising power plant of the EV, also has highly obtained people’s attention. Despite its good performance, the heating problem of the Li-ion battery on work has made a bottleneck problem for its development. High temperature will not only affect work performance such as the battery capacity, life, sometimes may even cause safety problems. Based on the finite element method of the thermal analysis, this paper simulated two kinds of Li-ion batteries and the temperature field distribution of batteries when finishing discharging with the ANSYS finite element analysis software, moreover, we made some simple battery cooling analysis, which aims to provide a Li-ion battery temperature rise of quantitative research.This paper firstly introduced the basic thermal analysis methods and analyzed their characters, we chose a suitable method for this research, the finite element analysis method. Based on the heat conduction theory, this paper built the3D differential model for the Li-ion battery. And then designed a charge and discharge operation test to detect temperature changes for the thin slice of lithium ion batteries in1C,3C,5C ratio, by analyzing temperature field at the same conditions with the ANSYS software, the only1~2℃error in comparison confirms the accuracy and feasibility of the method presented in this paper. After that, this paper discussed the influence of the different discharge rate, the different coefficient of convection heat and the different environmental temperature for the temperature field of the battery, and the results showed that the bigger the discharge rate, the smaller the coefficient of convection heat, the higher of the environmental temperature, the bigger the rise and difference of temperature and the bigger the area of the high temperature of the battery. Then after the establishment of the Li-ion battery cube model, we did the same temperature field of calculation, and the comparison with the temperature field of the battery at the same ratio showed that the batteries’ temperature field redistributes and the temperature had improved10℃. Finally extending to the analysis of temperature field of simple battery radiation condition and compared the heat dissipation effect of serial heat and parallel heat, and the results showed that the parallel has better effect for the rise of temperature and evenness of the battery. By using the large finite element analysis software ANSYS, this paper simplified the complex thermal conductivity and convective heat problems and also gave a solution, and again analyzed the heating effects of the Li-ion batteries, all of these will provide reference for the solution of exothermic question of the Li-ion battery and the design of the battery management system.