Application Research Of Heating Graphite Film And Thermal Conductive Graphite Film On Thermal Management Of Electric Vehicle Battery

Under the dual pressure of energy and environmental issues,the advantages of electric vehicles are increasingly prominent.When the lithium battery is charged and discharged at high power,the heat is severe,which may cause dangers such as thermal runaway,which is not conducive to the promotion of electric vehicles in all fields.Battery pack thermal management improves battery performance.The development of new types of battery thermal management is of great significance to the development of electric vehicles.Based on the excellent electrical and thermal conductivity of graphite materials,this topic prepares the heating film and high thermal conductivity film respectively,and applies it to the low temperature preheating battery for battery thermal management and high temperature heat dissipation.Design safe and efficient lithium ion battery charge/discharge circuit,using series and parallel to achieve high current charge / discharge under laboratory conditions;test charge/discharge battery heat,in the range of 12-20 A,battery charge / discharge current The larger the value,the more severe the battery heat.When the 20 A battery is discharged,the maximum battery temper ature can reach 40.7 °C.The graphite nanosheet(GNP)/polyurethane(PU)mixed slurry was prepared,and the composite heating film was prepared by film forming method.The resistance and resistivity of the heating film were controlled by changing the GNP content and film thickness.PU: GNP=10:4 preparation The heating film has a square resistance R□ of 100 Ω/□,a tensile strain value of 52%,and a tensile strength of 9.05 MPa.The prepared heat-generating film was applied to the preheating of electric vehicle battery.The results showed that the heating surface cell with a power surface density of 2000 W/m2 could heat the battery to 20 °C at 0.11 h,and the heating film was heated by 5000 W/m2 on both sides of the battery.The battery can heat all parts of the battery to 0 °C within 0.24 h,the battery temperature uniformity is good,and the maximum temperature difference is only 10 °C.The pyrolytic graphite film is used as the raw material,the polyurethane is used as the rubber layer,and the multilayer thermal conductive film is prepared by laminating hot pressing.The high thermal conductive film composite material with good thermal conductivity is prepared by the improved coating process,the lamination process and the hot pressing process.The thermal di ffusivity is 600 mm2/s,and the longitudinal thermal diffusivity is only 4.5 mm2/s.The mechanical properties and thermal conductivity of the multilayer high-thermal composite film prepared by the laminated hot pressing process are enhanced.It is found that the heat-dissipating composite film has excellent heat dissipation effect.In magnesium and aluminum alloys;in the range of 1-16 layers,the more the number of thermal conductive films,the better the heat dissipation effect;in the range of 0-15 cm,the shorter the heat conduction path,the better the heat dissipation effect;Affects heat dissipation,but bending 90 o makes the heat dissipation effect worse;the liquid cooling plate is placed at the bottom of the battery module to dissipate heat,and the heat dissipation effect is relatively poor.The maximum temperature of the battery is 27.5 °C,but the structure is simple,and the original structure of the battery pack is less changed;The liquid-cooled plate is placed on the side of the battery modul e for heat dissipation,and the heat dissipation effect is good.The maximum temperature of the battery is only 24.5 °C,but the cost is high,and the original structure of the battery system is greatly changed.