Dynamic Microcalorimetry: Thermal Effects of Miniature Alkaline Cells under Load

A nonrigorous thermodynamic calculation is performed yielding an expression which relates the rate of heat evolution by a miniature battery under load to the current flowing through the cell. At small values of , the expression predicts a linear plot of vs. . To demonstrate this behavior, thermal effects of an cell are measured under various conditions of constant load. The heat evolution data vary linearly with over the range 0.300 μA, with a slope of 74.3 mV and an intercept of 2.1 μW. The slope gives a value of −0.175 mV/K for , corresponding to the formation of inactive as a discharge product at the anode. Additional data obtained for and cells with alkaline electrolytes are present. The heat release data do not vary linearly with current. Analysis of the discharge mechanism for the system is possible. The discharge mechanism for the, cathode can be represented by a simple reduction to elemental mercury with formation of inactive as the discharge product at the anode.