Carbon dioxide electrolysis device and method of operating carbon dioxide electrolysis device

Abstract

A carbon dioxide electrolysis device includes: a cathode configured to reduce carbon dioxide and thus form a carbon compound; an anode configured to oxidize water and thus generate oxygen; a cathode gas flow path facing on the cathode and configured to supply gas containing carbon dioxide; an anode solution flow path facing on the anode and configured to supply an electrolytic solution containing water; and a separator provided between the anode and the cathode. An aspect ratio of the cathode gas flow path is greater than 1 and 3 or less. In a cross-section along a direction perpendicular to a facing surface between the cathode and the cathode gas flow path in the cathode gas flow path, a fluid mean depth M of the cathode gas flow path and a depth h of the cathode gas flow path satisfy a formula: h/8≤M<h/4.

What is claimed is: 
     
         1 . A carbon dioxide electrolysis device, comprising:
 a cathode configured to reduce carbon dioxide and thus form a carbon compound;   an anode configured to oxidize water and thus generate oxygen;   a cathode gas flow path facing on the cathode and configured to supply gas containing carbon dioxide;   an anode solution flow path facing on the anode and configured to supply an electrolytic solution containing water; and   a separator provided between the anode and the cathode, wherein   an aspect ratio of the cathode gas flow path is greater than 1 and 3 or less, the aspect ratio being defined by a ratio of a depth of the cathode gas flow path to a width of the cathode gas flow path, and   in a cross-section along a direction perpendicular to a facing surface between the cathode and the cathode gas flow path in the cathode gas flow path, a fluid mean depth M of the cathode gas flow path and a depth h of the cathode gas flow path satisfy a formula: h/8≤M<h/4, the fluid mean depth M being defined by a ratio of a circumferential length of the cathode gas flow path to a cross-sectional area of the cathode gas flow path.   
     
     
         2 . The device according to  claim 1 , wherein
 the cathode gas flow path includes:   a first region facing on the cathode; and   a second region provided between the first region and an inner bottom surface of the cathode gas flow path, wherein   a width of the second region is wider than a width of the first region.   
     
     
         3 . The device according to  claim 1 , wherein
 the cathode gas flow path includes:   a first region facing on the cathode and having a hydrophilic first inner wall surface; and   a second region provided between the first region and an inner bottom surface of the cathode gas flow path and having a water-repellent second inner wall surface.   
     
     
         4 . The device according to  claim 1 , wherein
 the electrolytic solution contains a metal ion.   
     
     
         5 . The device according to  claim 1 , wherein
 the cathode contains at least one catalyst selected from the group consisting of copper, gold, and silver.   
     
     
         6 . The device according to  claim 1 , further comprising:
 an electrolysis cell including the cathode, the anode, the cathode gas flow path, the anode solution flow path, and the separator;   a gas supply configured to supply the gas to the cathode gas flow path;   a solution supply configured to supply the electrolytic solution to the anode solution flow path;   a power supply configured to apply a voltage between the anode and the cathode;   a refresh material supply including a solution supply source configured to supply a rinse solution to the cathode gas flow path; and   a controller configured to control operations of stopping the supply of the gas by the gas supply, stopping the supply of the electrolytic solution by the solution supply, and supplying the rinse solution to the cathode by the refresh material supply in accordance with request criteria of performance of the electrolysis cell.   
     
     
         7 . A method of operating a carbon dioxide electrolysis device,
 the carbon dioxide electrolysis device including:
 a cathode configured to reduce carbon dioxide and thus form a carbon compound; 
 an anode configured to oxidize water and thus generate oxygen; 
 a cathode gas flow path facing on the cathode and configured to supply gas containing carbon dioxide; 
 an anode solution flow path facing on the anode and configured to supply an electrolytic solution containing water; and 
 a separator provided between the anode and the cathode, wherein 
 an aspect ratio of the cathode gas flow path is greater than 1 and 3 or less, the aspect ratio being defined by a ratio of a depth of the cathode gas flow path to a width of the cathode gas flow path, and 
 in a cross-section along a direction perpendicular to a facing surface between the cathode and the cathode gas flow path in the cathode gas flow path, a fluid mean depth M of the cathode gas flow path and a depth h of the cathode gas flow path satisfy a formula: h/8≤M<h/4, the fluid mean depth M being defined by a ratio of a circumferential length of the cathode gas flow path to a cross-sectional area of the cathode gas flow path, 
   the method comprising:   supplying gas containing carbon dioxide to the cathode gas flow path and supplying an electrolytic solution to the anode solution flow path;   applying a voltage between the anode and the cathode to reduce carbon dioxide near the cathode of the electrolysis cell to form a carbon compound and to oxidize water or hydroxide ions near the anode to generate oxygen; and   stopping the supply of the gas and the electrolytic solution and supplying a rinse solution to the cathode gas flow path, in accordance with request criteria of performance of the electrolysis cell.