Study On Mechanism Of Microprocess In Membrane Separation And Lithium-Ion Battery By Multiscale Simulations

With the rapid economic development, environmental pollution is increasingly serious and the energy crisis is gradually highlighted, the challenges faced by humanity are more austere. Therefore, environmentally friendly technologies and green energy attract much attention and are urgently needed. Membrane separation and lithium-ion battery are considered to be cutting-edge technologies, which effectively address the problems of environment and energy. A profound understanding on mechanism of microprocess will greatly promote the development of these cutting-edge technologies. Meanwhile, with the development of computer hardware and software technologies as well as computational simulation theory, multiscale simulation could play a more important role in these studies. Therefore, this paper studies mechanism of microprocess in membrane separation and lithium-ion battery by multiscale simulation. This study provides some useful information for promoting membrane separation and lithium battery technology and resolving environmental and energy issues.In the membrane separation aspect, this paper studies the effect of pore size and shape, adsorption of gas molecules and bias pressure on the separation process with porous graphene to separate hydrogen from coal gas, and explores the mechanisms of porous graphene membrane separation process. Studies have revealed that pore size and shape and bias pressure could significantly affect the efficiency of the membrane separation. The impact of adsorption of gas molecules in the system, however, is very weak. The process through the porous graphene for H2 is controlled by the entropy change; however, the processes through the porous graphene for CO, CH4 and H2S are dominated by the internal energy change. The results indicate the porous graphene effectively separate hydrogen from coal gas. A pore structure with high permeability and high selectivity has been obtained in this study.In the lithium-ion battery aspect, the paper studies the microscopic structure of a conventional carbonate electrolyte, the type, distribution and oxidation potential of clusters. The effect of Fluoroethylene Carbonate on microstructure and properties of traditional carbonate electrolyte has also been investigated. Our studies have revealed that short-range of electrolyte is structural ordering, ions and solvents competitively participate in lithium-ion coordinated. The oxidation potential of the electrolyte is determined by the oxidation potential of various clusters in the system. The addition of Fluoroethylene Carbonate almost dose not change in short-range order of the lithium-ion surrounding structure, but it has changed the type and the relative number of clusters in system. This makes the addition of FEC improve the performance of high-voltage lithium-ion batteries.