Jones-Dole Coefficients and Conductivity Studies on Electrolyte Solutions of Magnesium Borohydride in Mixtures of 1,2-Dimethoxyethane–Propylene Carbonate and 2-Methoxyethyl Ether–Propylene Carbonate

Abstract

The study on the competing influences of ion-ion, ion-dipole and dipole-dipole interactions by the species in magnesium borohydride [Mg(BH4)2] organic electrolyte solutions is reported. The organic electrolyte solutions were formulated by dispersing Mg(BH4)2 salt concentrations of 0.01, 0.05, 0.10 and 0.50 M in mixed solvent systems of 1,2-dimethoxyethane (DME)-propylene carbonate (PC) and 2-methoxyethyl ether (DGM)-propylene carbonate (PC). The density, viscosity, conductivity and dielectric constant were determined at different system compositions. The measured viscosity data varied with concentration according to Jones-Dole equation, while the resolved coefficients revealed that DME-PC and DGM-PC mixtures acted as solvates in the Mg(BH4)2 organic electrolyte solutions. The A coefficient values for DME-PC and DGM-PC systems increased progressively with mole fractions over the entire range studied. The B coefficient values for the electrolyte systems were found to exhibit minimum value at 0.822 and 0.095 mole fractions of DME and DGM respectively. The experimental conductivities of the electrolyte solutions measured at temperatures of 298.15, 308.15, 318.15, 328.15 and 338.15K increased with increase in temperature from 0 -50 % vol. composition range; and thereafter, decreased for both DME-PC and DGM-PC systems. This suggests that the most preferred mix ratio of the studied systems is 50 % vol. of component (DME or DGM) for optimum battery performance.