A liquid sulfur dioxide battery

Graduation date: 1965A liquid sulfur dioxide battery, such as K/KCl SbCl₅ (0.25\ud molar) + IBr₃ (15 %wt) + SO₂ (1)/carbon matrix is shown to have an\ud open circuit voltage greater than 3.70 volts and an initial voltage of\ud 3.15 volts, decreasing to 2.40 volts in 10 minutes at a current density\ud of 20 ma./sq. cm. at a temperature of 20°C. The anode and cathode\ud are in a parallel arrangement and are separated by a distance of\ud 0.15 cm. thus simulating the actual conditions in a wafer type battery.\ud The battery cell is tested at four temperatures in the range\ud 20°C to -44°C. The performance decreases at the lower temperatures.\ud The individual types of polarization, such as activation, concentration,\ud and IR drop are isolated. Activation polarization is evaluated\ud for the Br°-Br⁻ cathode and the Zn⁰-Zn⁺⁺ anode by the double\ud pulse galvanostatic method. The rate constant, k[subscript s], for the Br⁰-Br⁻ reaction\ud is evaluated to be 0.23 cm./sec. at -20°C. Concentration\ud polarization is mathematically shown to be very small at the current\ud densities studied (less than 100 millivolts at 20 ma./sq. cm.). The\ud IR drop in the electrolyte contributes appreciably to the total polarization\ud of the cell. However, the largest single factor in the total\ud polarization of the cell is the corrosion film formed on the anode surface\ud by the reaction of the anode with the liquid sulfur dioxide electrolyte.\ud Oxidizing agents, such as water, anhydrous ferric chloride,\ud and anhydrous antimony pentachloride appear to alleviate this polarization.\ud somewhat.\ud Polarization data are tabulated for the dissolution of zinc, magnesium,\ud calcium, lithium, sodium, and potassium. Data are also\ud tabulated for the reduction of IBr₃ on porous stainless steel, flat\ud stainless steel, and a porous carbon matrix