(591a) Molecular Dynamics Simulation Study on Dicationic Ionic Liquid Electrolytes in Supercapacitors

Room temperature ionic liquids(RTILs)-based supercapacitors has attracted increasing research interests due to the outstanding electrochemical properties of RTILs, such as high electrochemical stability and wider electrochemical windows, endowing them with high energy density. Monocationic ionicliquids(MILs) are the most frequently investigated RTIL electrolytes. Recently, dicationic ionic liquids (DILs) composed of the dication carrying two unit charges and associating with two anions are winning attentions due to their high thermal stability and low volatility. Thus, DILs can be excellent electrolyte candidates for supercapacitors working at extreme environmental conditions. In this work, we investigate the capacitive performance of DIL electrolytes in graphene electrode-based supercapacitors by molecular dynamics simulation. A variety of factors influencing the DIL performance in supercapacitors including alkyl chain length, anion type, the symmetry of dications as well as solvents are taken into account. Moreover, comparison of the interfacial behaviors of MILs and DILs in electric double layer(EDLs) of supercapacitors help reveal the hidden correlation between RTIL structures and their capacitive performance.