Research On The Cooling Methods Of Lithium-ion Battery Thermal Management System

In recent years,resource consumption and environmental pollution have brought great challenges to all countries in the world,especially petroleum consumption and exhaust emissions.In order to improve resource consumption and environmental pollution,countries around the world have issued corresponding policies,including the development and application of new energy vehicles.As the core power source of new energy vehicles,lithium-ion battery has the advantages of long service life,strong adaptability and high energy density.However,it also has the disadvantages of high temperature inside the battery module and heat cannot be emitted in time,which leads to the danger of battery combustion or even explosion.Therefore,it is necessary to study the thermal management of lithium-ion batteries and battery modules.Firstly,18650 single lithium-ion battery and battery module are taken as the research object to analyze its working principle and heat generation mechanism.Secondly,the accuracy of temperature field simulation of single cell is verified on the basis of single cell experiment.Finally,the temperature field of the battery module is simulated under different cooling modes,and the optimal cooling model is selected.The main research contents of this paper are as follows:(1)Through the temperature field simulation and experiment of single lithium-ion battery at different discharge rate,it was found that the relative error of simulation and experimental results is not more than 5%,which verified the accuracy of temperature field simulation of single lithium-ion battery,and laid a foundation for the temperature field simulation of battery module in the future.(2)According to the different cooling methods,air cooling battery module,liquid cooling battery module,phase-change material cooling battery module and heat pipe cooling battery module were constructed respectively.The four battery modules were divided into single-layer battery modules and double-layer battery modules according to different battery arrangement modes.The temperature fields of discharge rate and initial temperature of the four battery modules were simulated at 2C and 298.15 K,respectively.The optimal battery modules for each cooling mode were selected according to various temperature indexes.Combined with the cooling conditions of different cooling modes,the temperature field of four optimal battery modules was simulated respectively.The optimal cooling conditions of each battery module were selected by combining the simulation results and the actual situation of vehicle running.(3)Through the simulation results,it was found that the maximum temperature and average temperature of the heat pipe battery module exceed the safe operating temperature range,so the heat pipe cooling and liquid cooling coupling method was adopted to improve the heat dissipation capacity of the battery module.The temperature indexe of the above four optimal battery modules were compared with those of the heat pipe/liquid cooling coupling battery module.The results showed that the heat pipe/liquid cooling coupling battery module can obtain better heat dissipation effect under the premise of ensuring the temperature uniformity.There were 83 figures,9 tables and 75 references.