Electrode configuration of electrolysers to protect catalyst from oxidation

Abstract

The invention relates to an electrode configuration of electrolysers using oxygen storage material to prevent oxidation of anodic active catalyst layer where oxygen storage material will be preferentially oxidised prior to anodic active catalyst. The inventions also relates to the use of hydrogen storage material with cathodic active catalyst to supply hydrogen to react with oxygen supplied from anodes when a reduction load is connected between the anode and cathode. One configuration utilises of individual layers containing oxygen and hydrogen storage materials, active catalyst layers, perforated current collectors, monopolar plates and a porous separator. A reduction load is used during operation of the electrolyser to convert metal oxides into pure metal by consuming oxygen from the electrolyser cell during stand by mode, shut down mode and intermittent operation, which will increase the durability of electrodes.

1 . An electrolyser comprising an anode and a cathode and having an electrode configuration with oxygen storage material deposited on the positive anode of the electrolyser in contact with anodic active catalyst material to prevent oxidation of the anodic active catalyst material by means of preferential oxidation of the oxygen storage material. 
     
     
         2 . The electrolyser of  claim 1 , comprising a unidirectional, resistive reduction load across the anode and cathode to break the oxides from the anode to supply oxygen to react with hydrogen stored at the cathode. 
     
     
         3 . The electrolyser of  claim 1 , wherein the oxygen storage material and the anodic active catalyst material of the anode is deposited in one of adjacent layers in direct contact and a mixture. 
     
     
         4 . The electrolyser of  claim 3 , wherein the oxygen storage material and the anodic active catalyst material of the anode is deposited by a technique selected from the group comprising spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating and painting. 
     
     
         5 . The electrolyser of any  claim 1 , wherein the oxygen storage material and the anodic active catalyst material are provided in at least one layer having a thickness and the thickness of the layer is in the range of 0.1 microns to 10 millimetres. 
     
     
         6 . The electrolyser of  claim 1 , wherein the oxygen storage material comprises a material selected from the group comprising ceria, zirconium and other similar materials which are preferentially oxidised relative to the anodic active catalyst. 
     
     
         7 . The electrolyser of  claim 1 , wherein the anodic active catalyst comprises a material selected from the group comprising silver, nickel, alloys of silver and nickel, titanium, platinum, iridium, ruthenium, gold and other suitable catalyst materials for oxygen evolution reactions. 
     
     
         8 . The electrolyser of  claim 1 , wherein the surface area of the active catalyst material and oxygen storage material is in the range of 0.1 m 2 /g to 1000 m 2 /g. 
     
     
         9 . The electrolyser of  claim 2 , wherein the reduction load is configured for use during stand-by mode, shut down mode, at the start up stage and at open circuit voltage of the electrolyser. 
     
     
         10 . The electrolyser of  claim 2 , wherein the unidirectional reduction load comprises at least one of a diode and a resistor and another type of electronic circuit to ensure the direction of flow of electrons from the cathode which produces hydrogen to the anode which produces oxygen. 
     
     
         11 . The electrolyser of  claim 2 , wherein, in use, the open circuit voltage of the cathode against a platinum reference electrode is lowered to substantially zero volts by means of the reduction load by consuming oxygen from the metallic oxide from the anode to react with hydrogen from the cathode under the reducing voltage. 
     
     
         12 . The electrolyser of  claim 2 , wherein the reduction load is configured to be applied in one of constant current mode and constant power mode. 
     
     
         13 . The electrolyser of  claim 2 , comprising hydrogen storage material deposited on the negative cathode in contact with cathodic active catalyst material to supply hydrogen under the reduction load to react with oxygen from the anode. 
     
     
         14 . The electrolyser of  claim 13 , wherein the hydrogen storage material and the cathodic active catalyst material of the cathode is deposited in one of adjacent layers in direct contact and a mixture. 
     
     
         15 . The electrolyser of  claim 14 , wherein the hydrogen storage material and the cathodic active catalyst material of the cathode is deposited by a technique selected from the group comprising spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating and painting. 
     
     
         16 . The electrolyser of  claim 13 , wherein the hydrogen storage material and the cathodic active catalyst are mixed together and deposited onto a cathodic perforated current collector. 
     
     
         17 . The electrolyser of  claim 1 , comprising an anodic perforated current collector and a cathodic perforated current collector having porosity and open area from 10% to 90%. 
     
     
         18 . The electrolyser of  claim 1 , wherein the electrolyser is of a type selected from the group comprising alkaline, proton exchange membrane, solid oxide, other electrochemical cells, including fuel cells and batteries including alkaline, acidic, proton exchange membrane and solid oxide batteries. 
     
     
         19 . The electrolyser of  claim 2 , wherein the electrolyser is configured to apply the reduction load manually or automatically for switchover from normal operation to intermittent operation, stand-by mode and the start up stage of the electrolyser.