(189u) A Combined Molecular Dynamics and Experimental Study of an Imidazolium Based Ionic Liquid Electrolyte Solution for Low Temperature Applications

Imidazolium based ionic liquids are well known for their versatility as a solvent for room temperature and high temperature applications; however, their low temperature characteristics have not been studied. This investigation utilizes computational and experimental work to further study and design an imidazolium based ionic liquid electrolyte solution for space applications that can retain liquid properties at extremely low temperatures. The solution, containing an imidazolium based ionic liquid, water, lithium salt, and ionic liquid co-solvent, was modeled using the Gromacs 5.1.4 package in a temperature range of 25 ºC to -120 ºC. For each simulation, the molecules were randomly inserted into a 5x5x5 nm box and simulated under an NPT ensemble. Radial distribution functions indicate increased interactions and possible hydrogen bonding between water molecules and anions as temperature and water content is decreased. Self-diffusion coefficients were also calculated and show a nonlinear decline as the solution reaches colder temperatures. Experimental data including differential scanning calorimetry curves, viscosity, and conductivity measurements further support the trends from the simulations. Water concentration has a strong effect on glass transition temperature, viscosity and conductivity of the studied system. The results from this investigation show potential for ionic liquid electrolyte systems to be employed in low temperature applications.