| Summary: | 碩士 === 國立清華大學 === 動力機械工程學系 === 102 === The main propose of this thesis is to simulate blend molten salts by molecular dynamics (MD) and first principles molecular dynamics (FPMD) techniques. It is followed by calculating the ionic conductivity and thermal conductivity in order to analyze how the molten electrolyte affect the operation of a thermal battery. Furthermore, we compare our simulation results with literatures to verify the pros and cons of different methods.
According to the literature survey, whether a thermal battery is good or not is based on the discharging life and efficiency. The important factors to the battery efficiency are ionic conductivity and thermal conductivity. They both will affect the ionic transportation. The battery life time and the melting point are also influential factors. In the simulation of ionic conductivity, we use both classical molecular dynamics and first principles molecular dynamics to simulate the behavior at high temperature. Then we calculate the ionic conductivity with Nernst-Einstein relation and thermal conductivity with reversed non-equilibrium molecular dynamics (RNEMD) algorithm. Comparing to some other non-equilibrium molecular dynamics (NEMD) methods, RNEMD has been found to have better convergence.
Finally, we try to simulate the process of cooling down temperature of eutectic-salts electrolyte and observe the region of discontinuation to evaluate the melting point. It is expected to build a complete software tool for molten salt simulation to replace the costive in experiments and to optimize the battery design in a more efficient way.
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