Integrally heated electrochemical cell method and apparatus

Abstract

A novel electrochemical cell including a solid electrolyte heated to an elevated temperature for operation and an integral cell electrode/heater for heating the electrolyte. Solid electrolyte embodiments are described. The integral electrode/heater is applied to a surface of the solid electrolyte and is resistively heated by an alternating electric current. A portion of the solid electrolyte may also be resistively heated. The described or comparable cells may be incorporated into an oxygen detector or similar apparatus where the apparatus is operated by alternately heating the cell and measuring the emf developed by the cell across its electrode. The invention is also, in part, a unique, solid electrolyte-integral cell electrode/heater configuration which provides a zone of uniform maximum heating at a predetermined location within the electrolyte and which, when used with a suitable resistive heating electric current, confines the current to the integral electrode/heater prolonging cell life. Another aspect of the invention is the use of a radio frequency alternating electric current for resistively heating an electrochemical cell. Preferably, the radio frequency selected is sufficiently high so as to eliminate any offsets in the emf developed by the cell which are caused by the heater current. The invention also includes an apparatus for measuring the concentration of particular gases, such as oxygen, incorporating either and, preferably, both other inventive aspects of the invention. The preferred cell configuration reduces the complexity of such an apparatus by eliminating the auxiliary heat source and provides a more accurate and reliable electrochemical sensing cell. Radio frequency heating allows the operations of cell heating and emf measurement to proceed independent and concurrently and provides a continuously responding, self-heating detection apparatus.