Electrocatalytic Activity of Phthalocyanines in Secondary Lithium Cells

The feasibility of cathodes containing low molecular unsubstituted phthalocyanines in secondary lithium cells was studied by Yamaki and Yamaji. They reported values of discharge capacities of more than 17 electrons per molecule of phthalocyanine requiring the intercalation of the equivalent number of charge compensating lithium cations. The extensive literature concerning the properties of phthalocyanines, namely, electrochemical and chemical redox equilibria, suggests a reversible reduction of up to four electrons per molecule. The apparent discrepancies gave rise to a more detailed investigation of the electrochemistry of the cell. At the same time, the properties of low molecular copper octacyanophthalocyanine 2 and copperpolyphthalocyanine 3 were tested in the same cell reaction. The structures of the compounds are given.