Research On Battery Thermal Management Of Large-Capacity Lithium-ion Battery Based On Phase Change Material And Heat Pipe

The development of energy storage system is the key support and guarantee to achieve the carbon peak and neutrality targets,and promote energy transformation.The lithium-ion battery is the most advantageous energy storage technology,widely used in new energy vehicles,energy storage systems and consumable electronic products and other systems.Suitable temperature scales and small temperature differences are the premise to ensure high performance and long life of lithium-ion battery,so it is particularly important to development the efficient battery thermal management system(BTMS).In this thesis,large-capacity pouch lithium-ion battery of 500Ah is selected as the research object.The combination of composite phase change microcapsule material(PCM)and flat heat pipe is selected to verify the effect of BTMS,and it is expected to reduce the maximum temperature rise,and improve the temperature uniformity on battery and between batteries in series.The main research contents are as follows:In First part,the experimental testing platform is built to test the basic parameters and temperature rise characteristics of large-capacity lithium battery.The relationship between ohmic resistance and polarization resistance,as well as the mathematical model of total heat production composed of reversible heat and irreversible heat,are established at different temperatures and different charge-discharge rates.Secondly,the heat dissipation effect of BTMS based on the combination of PCM and heat pipe is verified by experiments.For high discharge rates,increasing the thickness of PCM can reduce the temperature rise and temperature difference,and the thicker the thickness,the more obvious the effect is.10mm PCM can reduce the temperature rise of the battery by 4.2℃ at 1C discharge rate.The addition of heat pipe can further reduce the temperature rise of the battery by 0.5℃ and the temperature difference by 2.7℃.The optimal configuration of BTMS is obtained through comparative experiments.Experiments are carried out to verify the heat dissipation effect of BTMS during six consecutive 1C high-rate charge and discharge cycles of one battery and threebatteries in series.The results show that the maximum temperature of the battery could be stabilized from 43℃ to 37.5℃,and the maximum temperature difference fluctuated from 8℃ to 3.5℃ after adding BTMS.The maximum temperature rise of the triple series battery is reduced by 6 ℃,the temperature difference is maintained below 6℃and the safe working time of is prolonged.The transient simulation model of thermo-electric coupling of lithium-ion battery is built.By comparing with the experimental data,the effectiveness of BTMS in continuous charging and discharge is verified.At the end of continuous charging and discharging,the maximum temperature of the top battery in three-series decreases from 59.3℃ to 50.70℃,and the center battery decreases from 62.5℃ to 51.73℃.The maximum temperature difference between modules decreases from 3.2℃ to 1.03℃,which improves the temperature uniformity.Finally,this thesis anallyzes the influence of phase change temperature on BTMS,higher phase change temperature will start to occur later,so that the temperature of the battery remains at a higher level,lower phase change temperature can control the battery temperature in advance,but the high temperature zone will completely melt too early to absorb the latent heat,the temperature and temperature difference gradually increase.The phase change temperature of 35℃ is more suitable for continuous charge and discharge of 1C.