Grand canonical Monte Carlo investigations of electrical double layer in molten salts

Results of the Monte Carlo simulation of the electrode/molten salt interface are reported. The system investigated was modeled by the restricted primitive model of electrolyte being in contact with the charged hard wall (hard spheres of diameter d=400 pm and relative permittivity epsilon(r)=10). The temperature analysis of the mean activity coefficient gamma(+/-), heat capacity C(v) and radial distribution function, g, indicated the range of temperatures of the study. Calculations for the electrode/electrolyte interface were carried out for temperatures 1300, 1400, and 1500 K and in the range of the electrode charge densities sigma from 0.025 to 0.5 C m(-2). Singlet distribution functions showed a multilayer structure of the electrolyte in the vicinity of the electrode surface. The structure depended on the electrode charge, but not much on temperature. The capacitance curves had a parabolalike shape with the maximum located at sigma=0. This result is not consistent with the Gouy-Chapman theory, but has been confirmed by the modified Poisson-Boltzmann theory, which includes the correlation and exclusion volume effects.