CONDUCTIVITY OF LOW-TEMPERATURE ELECTROLYTES FOR MAGNESIUM BATTERIES

Specific conductivities have been determined for MgCl2, MgBr2, Mg(ClO4)2, 2 M Mg(ClO4)2 + x M MgCl2, and 2 M Mg(ClO4)2 + x M MgBr2 (where x = 0.1 to 2 M) in pure water over the concentration range 0.1 to 3 M at +20, + 10, 0, -10 and -20-degrees-C. The conductivities increase in the order MgBr2 > MgCl2 > Mg(ClO4)2. Conductance maxima have been evaluated and the values of the 'a' and 'b' constants of Casteel-Amis equation have been obtained. A comparative study with the available literature data for MgCl2 has been undertaken. Cells comprising Mg/electrolyte/m-dinitrobenzene (1 V; 3 A h) have been fabricated and tested at +20 and -20-degrees-C using the maximum conductivity of the different electrolytes. Mixed electrolytes have also been investigated. From the observed discharge behaviour, 2.0 M Mg(ClO4)2 appears to be the most promising electrolyte solution for practical magnesium batteries that are required to operate over a wide temperature range.