Cathode electrode for operation under conditions of reverse polarity voltage

Abstract

Abstract A cathode electrode surface is composed of an Au-Ag alloy of 40 to 90 wt. percent Au, the remainder Ag. The Ag ions are effectively locked into (bound into) the alloy of the cathode electrode surface by the Au constituent so that when the surface is contacted by a liquid or semi-liquid electrolyte, such as sulfuric acid and the like, and subjected to reverse polarity voltage conditions so that the cathode electrode functions as an anode electrode, harmful amounts of Ag are not dissolved in the electrolyte and deposited on the anode electrode. Under conditions of reverse polarity voltage, the anode electrode tends to function like a cathode electrode and the cathode electrode tends to function like an anode electrode. A Au content of less than about 40 wt. percent in the Au-Ag alloy intended for use as a cathode electrode is insufficient to effectively lock Ag ions in the alloy under conditions of reverse polarity. Consequently, harmful amounts of Ag may be dissolved in the electrolyte from the surface of a Ag containing cathode electrode when subjected to a reverse polarity voltage and deposited on the anode electrode. A Au-Ag alloy wherein the Au content is greater than about 90 wt. percent of the alloy, a loss is experienced in effective cathode capacitance over extended life of the capacitor.

Inventors

• 👤 L Shoot

Bibliographic Details