Research On Shape-stabilized Phase Change Materials Based On SEBS For Thermal Management System

Lithium-ion batteries play an important role in achieving emissions targets by integrating renewable energy technologies and electric vehicles(EVs).However,the lithium-ion batteries exhibits clearly temperature-sensitive performance.To ensure safe operation,the thermal management system(TMS)should keep the batteries within the optimal operating temperature range and maximize the temperature uniformity.In this paper,based on the modification research of PCM,the enhancement and optimization of PCM's thermal performance,and the selection of PCM's styling agent,a shape-stable composite phase change material(SCPCM)was prepared.Subsequently,the phase change process of the prepared composite phase change material was visualized.In order to further verify the feasibility of thermal management of phase change materials,SCPCM with superior comprehensive performance was selected as the heat dissipation medium of thermal management system,and SCPCM thermal management system was constructed.For high-power battery modules,an active PCM thermal management system(combination of liquid cooling and PCM)is proposed to optimize the cooling performance of the SCPCM thermal management system.The main research contents and conclusions include:1.Using expanded graphite(EG)as the main thermally conductive framework and Fe₃O₄-MGO as thermally conductive particles,a series of composite phase change materials(CPCM)with enhanced thermal conductivity were prepared.The thermal conductivity of CPCM isoptimized through reducing the particle size.Using hydrogenated styrene-butadiene block copolymer(SEBS)as the supporting material,it was compounded with the optimized CPCM to prepare a shape-stable composite phase change material(SCPCM).The results show that the addition of Fe₃O₄-MGO can improve the thermal conductivity of CPCM,and Fe₃O₄-MGO has a certain phase change enthalpy.EG-100 can further enhance the heat transfer performance of the composite material.When it is 5wt%,a heat conduction channel can be built inside the PA.Compared with EG-80,the thermal diffusion coefficient is increased by 42%.SCPCM has good thermal performance,shape stability,and thermal memory.2.A visual test platform was built to investigate the heat transfer characteristics of the phase change process of the composite material,and compare the effects of the proportion of the added material on the composite phase transition process.The results show that the comprehensive heat transfer effect during the phase transition is affected by the convection and heat conduction,and the inhibition of natural convection is positively correlated with the proportion of added materials.6wt%thermal conductivity enhancement materials(5wt% EG and 1wt% Fe₃O₄-MGO)can improve the overall heat transfer performance.For the SCPCM case,the melting process is similar to CPCM4 *(5wt% EG and 1wt% Fe₃O₄-MGO).However,due to the three-dimensional network structure of SEBS,the apparent activation energy of the phase change of the composite material is increased,and the inhibition effect and latent heat of SEBS are reduced.Compared with CPCM4* case,the melting time and maximum temperature of SCPCM are increased by 592 s and 7 ?,respectively.However,the phase change material has good shaping effect.3.The SCPCM is selected as the heat dissipation medium in the PCM thermal management system,and a PCM thermal management system is designed based on the heat generation law of the battery.During the charge and discharge cycle,the thermal characteristics and cycle performance of the three battery modules(NO-PCM,PCM and W-PCM)are compared.The results show that the W-PCM battery module shows the best heat dissipation performance among the three cooling methods.The PCM battery module shows the bestcooling effect when the discharge rate is 3C,the maximum temperature and the maximum temperature difference are 53.47 ? and4.8 ?,respectively.At 5C discharge rate,the heat dissipation effect of PCM battery module decreases due to the SCPCM material reaching thermal saturation.As for the W-PCM battery module,the maximum temperature and temperature difference of the module can be kept within 50 ? and 5 ?.