Effect of Acetonitrile on the Interfacial Microstructure of Aqueous Ionic Liquids/Graphene in Supercapacitor
The wetting properties of ionic liquid electrolytes on the graphene surface are crucial for the energy storage performance of graphene/ionic liquids supercapacitors.Due to the hygroabsorp-tion of ionic liquids,it inevitably absorbs water during the process of preparation and application,and the existence of water affects the distribution of ions at the solid-liquid interface and the wetting properties of ionic liquids on the graphene surface.The organic solvent acetonitrile is anticipated to decrease the viscosity of ionic liquids and mitigate the impact of water on the capacitive properties.In this paper,the microscopic mechanism of acetonitrile on the wetting characteristics of ionic liquids on the graphene surface.The results revealed that as the acetonitrile content increased,specifically when the ratio of nH2O to nACN varies from 1∶1 to 1∶8,the wettability of both hydrophilic and hydropho-bic aqueous ionic liquid droplets on the graphene surface was notably improved,the corresponding contact angles decreased by 42.46° and 24.30° respectively.And the wettability enhancement was more pronounced in the hydrophilic ionic liquids system.Through analysis of the one-dimensional and two-dimensional density profiles of each ion and molecule,as well as the radial distribution func-tion between ions/molecules,it was observed that acetonitrile molecules are distributed near the wall layer,and the addition of acetonitrile changes the distribution and interaction of cations,an-ions and water molecules at the solid-liquid interface,forming a partial desolvation structure,which is conducive to improving the energy storage performance.Moreover,the existence of acetonitrile increases the diffusion rate of ions,and the interactions among cations,anions,water,acetonitrile,and solid wall effect the wettability of aqueous ionic liquids droplets on the graphene surface.The results deeply explore the interfacial microstructure of ionic liquids droplet on graphene,and provide an important guidance for the development and design of high-performance graphene/ionic liquids supercapacitors.
NETL
NSTL
万方数据
