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URN etd-0710118-121934
Author Hua-sheng Hsieh
Author's Email Address hsieh.hs98@gmail.com
Statistics This thesis had been viewed 5563 times. Download 157 times.
Department Mechanical and Electro-Mechanical Engineering
Year 2017
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Investigate the Adsorption and Diffusion Behaviors of Organic Molecules in Electric Double Layer Capacitors by Molecular Dynamics Simulation
Date of Defense 2018-07-20
Page Count 79
Keyword
  • Microstructure
  • CPM
  • Coarse-graining
  • EDLC
  • Molecular dynamics
  • Abstract Combining the advantages of constant potential method (CPM) and molecular dynamics (Molecular Dynamics, MD) simulation technology, this study constructs a new electric- double layer capacitor model that can observe the adsorption of molecules on the surface of the electrode and the diffusion process of ions internal microscopic structure, which can predicts the capacitance and charge and discharge rate of the supercapacitor. In the electrolyte part, the OPLS-AA (Optimized Potentials for Liquid Simulations All Atom) force field is used to describe the interaction between atoms in all-atom model, which was proven as good describing for organic liquid in previous work. So this study uses OPLS-AA as a force field to construct a topological structure, through molecular dynamics simulation to balance and generate a reference trajectory file, then refer to the Multi-Scale Coarse-Grained method (MSCG) developed by the Voth group, fitting the effective parameters of the Coarse grained (CG) model. In terms of electrode materials, two-dimensional graphene and three-dimensional activated carbon structure are used as electrode materials for symmetrical electric double layer capacitors. In this study, we aim to store the maximum capacitance. The first step is to compare the average squared displacement and the diffusion number of different concentrations in the three-dimensional periodic boundary system. The results show that as the concentration increases, the capacitance decreases, but the diffusion number decreases. The average number density distribution and capacitance of electrolytes in different concentrations were investigated in a graphene electrode system. The third step was to construct three density activated carbon electrode systems, we analyzed the molecular adsorption behavior of the microstructure in activated carbon electrodes at different electric potential. The results are closely related to the changes in the number density and capacitance. The aim of this project is to develop a powerful tool and provide some useful information for study the charging mechanism of supercapacitor and screen optimal electrode material and electrolyte solution.
    Keywords: Molecular dynamics, EDLC, Coarse-graining, CPM, Microstructure
    Advisory Committee
  • Shih-Jye Sun - chair
  • Chia-Hao Su - co-chair
  • Hsin-Tsung Chen - co-chair
  • Hui-Lung Chen - co-chair
  • Shin-pon Ju - advisor
  • Files
  • etd-0710118-121934.pdf
  • indicate access worldwide
    Date of Submission 2018-08-10

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