Investigation On The Thermal Management System Of Li-ion Battery Based On Phase-change Material Suitable For Climatic Conditions In Central South China

With the wide application of electric vehicles,the threat brought by the shortage of oil resources has been alleviated to a certain extent,and the clean power generation method has been re-emphasized,bringing new vitality to the development of the energy industry.However,the energy storage capacity and temperature sensitivity of lithium-ion batteries limit the development of electric vehicles.Improving the energy storage capacity of li-ion batteries is mainly by using new materials,while reducing the impact of temperature on the use of li-ion batteries can be achieved through thermal management.The thermal management strategy of phase-change material is characterized by simple structure,low cost,strong ability of temperature control,uniform battery temperature distribution and no additional energy consumption,so it is an ideal battery thermal management strategy.However,in the application of phase change material thermal management strategy,the key issues are selecting the appropriate type of phase change material,the amount of phase change material,and overcoming the disadvantages of passive thermal management strategy in low temperature environment.For this purpose,the thesis is supported by Changsha Technology Division Major Project [kh1601129].By means of theoretical analysis,numerical simulation and experimental verification,a 3×4 arranged cylindrical battery box was modeled,and the results of different cooling strategies and heat preservation strategies were compared.The main research work and innovation points of this paper are as follows:(1)The model of 18650 lithium-ion single battery and a 3×4 battery box was established,and computational fluid dynamics(CFD)software was used to simulate the temperature changes of single battery and battery box under different ambient temperatures and discharge rates,and the temperature distribution,rising situation and shortage of natural cooling of the battery were obtained.(2)In order to control the temperature rise and temperature difference of the battery,a PCM cooling model was established.By compared the temperature rise and temperature difference of battery boxes with different battery gaps,the influence of PCM dosage on cooling performance was analyzed.The results showed that the battery clearance should not be less than 3mm when using PCM1 and not less than2 mm when using PCM2.(3)In order to find the best cooling scheme,the two optimization schemes andthe original scheme are compared by simulation.The results showed that the scheme using 3mm thick PCM1 material had the best temperature distribution uniformity,while the scheme using 2mm thick PCM2 material had the lowest average temperature and the minimum volume.(4)For the battery box to be suitable for the climate of central south region,a PCM cooling battery case covered with an open insulation layer was designed through the test of insulation properties of different material types and thicknesses,as well as the analysis of the influence of the thermal insulation layer position,area,the temperature range on the heat dissipation performance.An all-weather thermal management solution that meets the requirement for insulation in low temperature environment and heat dissipation in high temperature environments was obtained.