A morphological investigation of electrodes for solid electrolytes

Abstract

using the techniques of image analysis, profilometry, gas permeability, mercury porosimetry, and gas adsorption, the morphological properties of porous electrode film (1 to 300/~m) materials are discussed. The materials include platinum paste which is utilized as electrodes for high-temperature oxygen-ion-conducting ZrO 2 electrolytes and for low-temperature solid-state protonic electrolytes. Also considered are plasma-sprayed nickel layers and silver membranes. It is shown that each of the five methods can be used to make quantitative evaluations of film electrodes. The electrode morphological parameters measured include particle diameter, pore diameter, porosity, three-phase line, thickness, surface texture, gas-flow/pressure, pore area, and surface area. A discussion of these properties as they relate to activation and concentration polarization of electrochemical cells is also presented. IntroductionThe morphology of the electrodes used in certain types of electrochemical cells has been known [1-9] to affect the performance of these devices. Of particular interest here is the three-phase cell consisting of a solid (ceramic) electrolyte (in which mobile ionic species migrate or diffuse), porous metal electrodes and reactant gas species. This structure may be compared with two-phase electrochemical cells containing a liquid or solid electrolyte and non-porous metal electrodes.A number of three-phase cells has been under intensive study. The cell with doped ZrO2 [1-9] as the electrolyte is an anionic conductor, having 02 ions as the mobile species. The operating temperatures of this cell is 800 to 1000 ° C. A cationically conducting cell based on the SrCeO3 electrolyte [10-13] also operates in this temperature range and has protons as its mobile species.Two protonic conductors which operate at 25 to 300°C have also been developed. The fl/fl"-A1203 [14][15][16] and Nasicon [17,18] formulations show promise as precursor electrolytes for fuel cells, electrolysers and sensors. In order for these materials to be used in hydrogen cells, it is necessary for the mobile cationic species to be exchanged for hydronium, H30 + , ions. A method for ion-exchanging the precursor material in powder form and then bonding the exchanged powder with an inorganic substance has been developed [19].A number of electrochemical devices have been reported which utilize the hydronium electrolyte;

Room Ionic Conduction in Beta Alumina Cell with Nanocomposite Electrodes

“…As opposed to previous work (9), both conventional and nanocomposite electrodes were deposited onto as-sintered membranes using a thick film technique. It is known that such technique provides very homogeneous partially sintered silver particles with submicron particle size (12). One of two identical membranes was painted with such paste from both sides with unpainted guard rings 3 mm in width.…”