Theoretical study of CH4 intercalation in sI clathrate hydrates for energy storage

Abstract

The sI methane clathrate hydrate system has been identified as a potential candidate for application as an energy storage material. Previous studies have utilized Monte Carlo (MC) simulations of this system, assuming it to be a two-dimensional (2D) lattice gas. Density Functional Theory (DFT) studies can be performed to enhance our understanding of the interaction of guest species, such as methane in different concentrations, and to facilitate comparison with MC simulations and the acquisition of different properties. DFT simulations were conducted to study the stability of methane in the sI clathrate hydrate, finding that one molecule per cavity in the system is the most stable configuration found, which is in agreement with MC. The configurations obtained validate previous studies from our group that model methane clathrate hydrates using a 2D lattice gas. Novel electronic density of states, bond order and charge density difference analysis with and without methane are performed. The intercalated system shows that it has van der Waals interactions, and there is a lower bond strength for the intercalated material, which could allow diffusion. The material has favorable interaction energy and stability, so further experimental and theoretical studies are suggested.