Molecular Dynamics Simulation Study Of Fundamental Properties Of Organic Electrolytes Based On Metal Ions

Energy, the foundation of human existence as well as social development, is one of the most important material basis and support for economic and social development in the world. As the fossil fuels are gradually depleted, the development of renewable energy and the hybrid vehicle put forward higher requirements for the new energy storage device. On this basis, the development of the supercapacitor is becoming increasingly important. Using molecular dynamics simulation, the fundamental properties of the metal-ions based organic electrolyte were studied under the micro/nano scale. Moreover, asymmetric behavior of positive and negative electrodes in carbon/carbon supercapacitors and its underlying mechanism were explored.In acetonitrile(AN) and propylene carbonate(PC) solvents, [Li][PF6], [Na][PF6], [K][PF6] and [TEA][BF4] were used as the electrolyte salts. With appropriate force fields, all kinds of simulations were run under different concentrations using molecular dynamics simulations. After equilibration, the radial distribution functions(RDFs) between ions and solvent molecules, as well as solvated ions' diffusion coefficient and their desolvation energy, were also calculated. In addition, molecular dynamics simulations were carried out to render a full-length understanding of experimental observations, that is, the motion and desolvation effects as well as the size of solvated ions impose influence on the asymmetric behaviors of supercapacitors. In this simulation two different electrolytes, [TEA][BF4]/PC and [Li][PF6]/PC, were employed in the electrochemical measurements.Here, many fundamental properties of solvated ions, such as solvated size, diffusion coefficient and desolvation energy were analyzed using molecular dynamics simulation. Our research would shed light on asymmetric behavior of electrodes in carbon/carbon supercapacitors and provide a possible strategy to obtain the symmetric capacitance of two electrodes in supercapacitors.