Method for mounting oxygen-consuming electrodes in electrochemical cells and electrochemical cells

Abstract

Method for the gastight and liquid-tight installation of oxygen-consuming electrodes in an electrolysis apparatus, and electrolysis apparatus for use in chloralkali electrolysis, in which particular regions are covered with an additional film having a composition comparable to the oxygen-consuming electrodes

1 . Method for the gastight and liquid-tight installation of one or more joining oxygen-consuming electrodes ( 1 ,  1   a ) in an electrochemical half cell ( 2 ), wherein creased regions ( 5 ) and/or cracked regions ( 6 ) of the oxygen-consuming electrodes ( 1 ,  1   a ) and/or abutting edge regions ( 7 ) and/or overlap regions ( 8 ) of adjacent oxygen-consuming electrodes ( 1 ) and ( 1   a ) occurring when the oxygen-consuming electrodes ( 1 ,  1   a ) are brought into juxtaposition with the frame ( 3 ) of the gas compartment ( 4 ) of the cell ( 2 ) are covered with an additional film ( 9 ) which has a composition comparable to the oxygen-consuming electrodes ( 1 ,  1   a ) and is thinner than the layer thickness of the oxygen-consuming electrode ( 1 ,  1   a ). 
     
     
         2 . Method according to  claim 1 , wherein the film ( 9 ) has the same catalytically active material as the oxygen-consuming electrode ( 1 ,  1   a ). 
     
     
         3 . Method according to  claim 1 , wherein the film ( 9 ) and/or the oxygen-consuming electrodes ( 1 ,  1   a ) are, independently of one another, based on a fluorinated polymer and a silver-containing catalytically active material. 
     
     
         4 . Method according to  claim 1 , wherein the catalytically active component in the film ( 9 ) and/or in the oxygen-consuming electrodes ( 1 ,  1   a ) comprises silver, silver(I) oxide or silver(II) oxide or mixtures of silver and silver oxide. 
     
     
         5 . Method according to  claim 1 , wherein the content of the catalytically active component in the film ( 9 ) comprises at least 50% by weight of silver oxide. 
     
     
         6 . Method according to  claim 1 , wherein the film ( 9 ) and/or the oxygen-consuming electrodes ( 1 ,  1   a ) comprises mixtures which, independently of one another, contain, as catalytically active component, from 70 to 95% by weight of silver oxide, 0-15% by weight of silver metal powder and 3-15% by weight of a fluorinated polymer, in particular PTFE. 
     
     
         7 . Method according to  claim 1 , wherein the film ( 9 ) and the oxygen-consuming electrodes ( 1 ,  1   a ) are pressed together after application of the film ( 9 ). 
     
     
         8 . Method according to  claim 1 , wherein the film ( 9 ) and the oxygen-consuming electrodes ( 1 ,  1   a ) join together at their contact points after application of the film ( 9 ) when the cell ( 2 ) is started up. 
     
     
         9 . Method according to  claim 1 , wherein the film ( 9 ) has a layer thickness of from 10 μm to 800 μm. 
     
     
         10 . Method according to  claim 1 , wherein the oxygen-consuming electrodes ( 1 ,  1   a ) have a layer thickness of from 0.1 to 0.8 mm. 
     
     
         11 . Electrochemical cell ( 2 ) having one or more adjoining oxygen-consuming electrodes ( 1 ,  1   a ), characterized in that wherein the oxygen-consuming electrodes ( 1 ,  1   a ) have creased regions ( 5 ), and/or cracked regions ( 6 ) of the oxygen-consuming electrodes ( 1 ,  1   a ) and/or abutting edge regions ( 7 ) and/or overlap regions ( 8 ) of adjacent oxygen-consuming electrodes ( 1 ) and ( 1   a ) occurring on installation on the frame ( 3 ) of the gas compartment ( 4 ) of the cell ( 2 ) and these regions are covered with an additional film ( 9 ) which has a composition comparable to the oxygen-consuming electrodes ( 1 ,  1   a ) and is thinner than the layer thickness of the oxygen-consuming electrode ( 1 ,  1   a ). 
     
     
         12 . Electrochemical cell ( 2 ) according to  claim 11 , comprising polytetrafluoroethylene (PTFE) in the gas diffusion layer of the oxygen-consuming electrodes ( 1 ,  1   a ). 
     
     
         13 . Electrochemical cell ( 2 ) according to  claim 10  having an electrically conductive flexible textile structure composed of metal threads as additional support element in the oxygen-consuming electrodes ( 1 ,  1   a ) and/or in the film ( 9 ). 
     
     
         14 . Electrochemical cell ( 2 ) with installation of oxygen-consuming electrodes ( 1 ,  1   a ) according to the method of  claim 1 . 
     
     
         15 . Method the electrolysis of NaCl wherein said electrolysis is carried out in the electrochemical cell of  claim 11 .