IR OXIDE ELECTRODE IN WATER, ORGANIC-SOLVENTS AND IN ROOM-TEMPERATUREMOLTEN-SALTS

The kinetics of oxidation and reduction of electrochemically formed Ir oxide films has been studied in organic solvents and in room temperat ure molten salts from the point of view of application of the Ir oxide electrode as a cathode in advanced rechargeable batteries. It has bee n shown that a stable and fast kinetic response of this electrode can be obtained in methanolic, acetonitrile and dimethylformamide solution s, provided the oxide is kept in its unaged form before the transfer t o the organic solution, and the resolvation of the Ir oxide film is fa cilitated either by prolonged cycling in the organic solution or by lo wering the water content of the solution and the oxide. In room temper ature molten salts, the Ir oxide is inactive, unless an organic solven t (acetonitrile) is added. The results are discussed in terms of the l imitation of the kinetics of the Ir oxide redox process by a diffusion of electrons through the oxide film and the need of small ions to bal ance the charge within the oxide film.