Method for manufacturing a high-temperature electrolyser or a high-temperature fuel cell comprising a stack of elementary cells

A method of manufacturing a high temperature electrolyzer (HTE) or a high temperature fuel cell, comprising a vertical stack of n elementary planar cells alternating with n+1 interconnection plates, each of the elementary cells comprising a planar porous anode and a planar porous cathode respectively positioned on each of the faces of a planar dense electrolyte, and brazed joints being provided at contact points between the elementary cells and the interconnection plates, the method comprising the following steps:

• a) preparing the planar porous anode and the planar porous cathode on each face of the electrolyte, the planar porous anode being an openworked anode with through holes, and the planar porous cathode being an openworked cathode with through holes, so as to leave exposed first surface areas of each of the faces of the electrolyte corresponding to the through holes in the anode and the cathode, the exposed first surface areas delimiting second surface areas of each of the faces of the electrolyte covered by the anode or the cathode at the locations provided for the brazed joints, wherein an elementary cell is obtained comprising the openworked anode and the openworked cathode, each having a thickness;
• b) depositing a brazing composition layer on the surfaces of the anode and of the cathode corresponding to the second surface areas, the brazing composition amount corresponding to an amount that, in the molten state, fills the whole porosity in the thickness of the anode or of the cathode to a level corresponding to the surface of the electrolyte in the second surface areas without protruding beyond the surface of the anode or of the cathode by a thickness of more than about 20% of the thickness of the anode or of the cathode, thereby forming an elementary cell provided with a brazing composition;
• c) repeating the preparing and depositing n times;
• d) successively stacking an interconnection plate and a cell, the interconnection plate and the cell being vertically stacked;
• e) repeating the successive stacking n times;
• f) stacking an n+1th interconnection plate;
• g) heating the stack formed by the elementary cells provided with the brazing composition and by the interconnection plates to a brazing temperature in order to melt the brazing composition, wherein the brazing composition fills the whole porosity in the thickness of the anode or of the cathode from their surface as far as the surface of the electrolyte in the second surface areas, without protruding beyond the surface of the anode and of the cathode by a thickness of more than about 20% of the thickness of the anode or of the cathode;
• h) cooling the stack from the brazing temperature to room temperature;
• and
• i) forming the electrolytes and the interconnectors with brazed joints.