Effect of macrocyclic compounds on the electrode processes in the lithium-thionyl chloride cells

Effect of metal complexes of the porphyrin series on reduction of thionyl chloride at smooth glassy-carbon and porous carbon black electrodes is studied by cyclic voltammetry and chronopotentiometry. Two effects are discovered: a proper catalytic effect and depassivation of the carbon cathode. It is found that the most active catalyst is cobalt tetraphenylporphyrin and the best depassivating agent is nickel tetraphenylporphyrin. The impedance technique and the discharge curves are used to show that introducing porphyrins into a thionyl chloride electrolyte alters the state of the passivating film on the lithium electrode and decreases the voltage dip. The theoretical conclusions obtained are confirmed by the tests conducted on model lithium-thionyl chloride cells.