Molecular Dynamics Of Organic Electrolyte In Double Carbon Layer Containers

Electric double layer capacitor, also known as supercapacitor, whose ultra high power density and long cycle life get more and more attention from people with the increasing requirements on the storage and cycle life. As the same time, the choice of capacitor material and electrolyte becomes more important. With the development of science and technology and the expansion of computer application field, it has become a trend to move traditional experiments to the computer to achieve the research goals in simulations, which can reduce unnecessary waste of resources, and also can get rid of many unreasonable experiments. Using molecular dynamics simulation method, a force field and model of an organic electrolyte are established in this work, and the structure of the organic electrolyte is studied.Spiro-(1,1’)-bipyrrolidinium tetrafluoroborate (SBP·BF4) and acetonitrile electrolyte has a good conductivity and electrochemical window. In this paper, the structure and charge distribution of [SBP][BF4] were calculated by software Material Studio 6.0 by quantization processing, combining with the published literature, an optimized force field was established, then a molecular dynamic simulation was carried out by LAMMPS software. The result shows that the calculated properties are very close with the experimental values, which proves the accuracy of the force field. The success lays the foundation for the simulation calculation of the supercapacitor.By using the organic electrolyte model, a double carbon layer model is established. Properties in different conditions of double layer capacitor are simulated under different voltages, such as distribution density and molecular structure of different levels, and the structures of different voltage are analyzed. The result shows that the charge density of the capacitor increases with the increase of voltage.