STUDY ON ANTI-LEAKAGE AND HIGH THERMAL CONDUCTIVITY COMPOSITE PHASE CHANGE MATERIAL FOR LITHIUM ION BATTERY THERMAL MANAGEMENT SYSTEM
At present,the lithium battery thermal management system using phase change materials(PCM)has been widely used,but how to solve the problems of leakage and low thermal conductivity of phase change materials is still a wide range of research prospects.Especially in high power working condition,the temperature of the battery is still not well controlled.In this paper,a new type of composite phase change material(CPCM)with excellent thermal conductivity and leak-proof performance is proposed.The joint cross-cross mesh of expanded graphite(EG)and diatomite can significantly improve the adsorption capacity and thermal conductivity of the CPCM.The results show that the CPCM containing 10%diatomite and 6%EG is heated at 50℃for 5 h and there is still no surface leakage,the PEG content reach 90%.The samples also show excellent stability in the thermal cycle test.After coupling the battery to the CPCM,we test the temperature variation of the battery under 8 different operating modes.Especially in 2C mode,when the battery is operating at a higher initial temperature(30℃),its maximum operating temperature can still be controlled below 40℃,and the temperature difference between each battery can be limited to about 2℃.At the same time,it is found that CPCM can provide excellent insulation performance for battery system at low temperature.After coupling with the CPCM,the discharge efficiency of the battery is improved by about 16.07%.When T0=30℃,the battery discharge efficiency reaches 91.67%at 1C mode.These excellent physical properties can enable CPCM-lithium battery composite model to be applied in a wider range of fields.
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