Molecular Dynamics Simulation Of Heat Transfer Through Solid-liquid Interface In Ionic-liquid-based Supercapacitor

In recent years,the rapid development of renewable energy has put forward higher requirements for the performance of energy storage devices.The supercapacitor is a new type of energy storage element,which has the advantages of long service life,high efficiency,and fast dynamic response,and has been widely used.As a kind of device with rapid charge and discharge as its main working form,supercapacitor will generate a lot of heat inside during its working process.Excessive heat,if not effectively distributed to the surrounding environment,will cause the operating temperature of the device to rise,which will greatly affect the performance of the supercapacitor,shorten the life of the device,and even lead to safety accidents.With the rapid increase of the scale of supercapacitor devices,it is necessary to study the heat transfer of supercapacitor.We used graphene as electrode material and ionic liquids as electrolyte,and established the corresponding molecular dynamics heat transfer model by using the classical molecular dynamics simulation method.According to the corresponding interface structure at the interface,we explored the factors affecting the heat transfer efficiency of graphene/ionic liquid interface.The main research results of this paper are as follows:When the electrode is charged,a stable electrical double layer structure will be formed near the electrode,which changes the structure distribution at the interface.The change of this structure increases the molecular tightness at the interface,which can increase the thermal conductivity of the interface by 110% at most.The existence of extra small adsorption peak at the negative electrode makes its heat transfer stronger than that at the positive electrode.Compared with the smooth interface,the heat transfer efficiency of the nanoscale rough interface is lower.This is because ions cannot enter the rough structure,resulting in fewer graphene carbon atoms participating in the heat transfer at the interface,which weakens the heat transfer at the interface.The effect of cation and cation composition on interfacial heat transfer is not as significant as that of charge,but the size of cation has little effect on interfacial heat transfer.When the electrode charge is not high,acetonitrile has little effect on the interfacial heat transfer.When the electrode charge increased to a certain extent,the effect of acetonitrile on the interface heat transfer of the negative electrode would be enhanced,but this effect would gradually weaken with the increase of the proportion of acetonitrile.When the ionic liquid contains water,the interfacial heat transfer has little effect.