(174ag) Study the Diffusion Mechanism and Diffusivity of Lithium Ions in the Ionic-Liquids-Added Electrolytes Using Molecular Simulation

For lithium ion batteries, traditional organic electrolytes suffer from the reactions between Li anodes and electrolytes. Ionic liquids were considered as additives as this problem was effectively relieved in the ionic-liquids-added electrolytes. However, the sluggish Li ion diffusion in ionic liquids has impeded the applications owing to its high viscosity. Therefore, it is necessary to study the diffusion mechanism of Li ions in the ionic-liquids-added electrolytes. In this study, dicationic ionic liquid(DIL) 1,n-bi (3-methylimidazolium-1-yl) alkane tetrafluoroborate (Cn(mim)2(BF4)2) were investigated as an additives in the propylene carbonate (PC) electrolyte. Molecular simulation results show that the solvation layer changed with the addition of DILs. Coordination numbers of anions in the Li ion solvation layer were reduced when there are a few DILs in the electrolyte, and then the diffusivity of Li ion was strengthened. With the increase of concentration of DILs, the viscosity of the system becomes the dominating factor affect the ions diffusivity. This work is expected to provide guidance for the development of new electrolyte additives.