Process of operating fuel-cell half cell with cupric-cuprous redox couple

Claim 1

In a process for operating an independent electrochemical oxygen-reducing fuel cell half-cell arrangement which utilizes a cupric-cuprous redox couple wherein Cuprous complex anions are converted to cupric complex anions by a continuously supplied stream of an oxidant to achieve an open circuit half-cell potential of at least 0.56 volts (v. S.C.E.) at 65* C., said process further comprising maintaining an electrical conductive electrode member in contact with an acidic catholyte having an excess of chloride ions, and maintaining in said catholyte a cupric-cuprous redox couple, said process further comprising during closed circuit conditions supplying electrons to the electrode member and converting cupric complex anions in the catholyte and in operative association with said electrode member to cuprous complex anions, said catholyte formed by dissolving cupric chloride, essentially free of cuprous chloride, in hydrochloric acid, the concentration of cupric chloride being at least 20 grams per liter, the concentration of the hydrochloric acid being at least 1%, and said electrode member being formed of graphite; the improvement which comprises maintaining the temperature of the catholyte, just prior to and during operation of the half cell, between about 65* C. and about 115* C. and continuously supplying sufficient amounts of oxidant and sufficiently well distributing said oxidant throughout the catholyte just prior to and during closed circuit operation to convert the cuprous complex anions back to cupric complex anions substantially instantaneously to prevent a buildup of any significant amount of nontransitory cuprous complex anions in the catholyte.