High temperature electrolyzer (HTE) having a stack of electrolysis cells and improved operating reliability and high efficiency

A module for high-temperature electrolysis, comprising:

• a sealed casing configured to contain steam containing at most 1% hydrogen, or an inert gas;
• a stack of elementary electrolysis cells, each formed of a cathode, an anode, and an electrolyte sandwiched between the cathode and the anode, wherein at least one interconnecting plate is fitted between two adjacent elementary cells, in electrical contact with an electrode of one of the two elementary cells and an electrode of the other of the two elementary cells, wherein the interconnecting plate includes at least one cathodic compartment and at least one anodic compartment for gas to flow respectively in the cathode and in the anode, and wherein the stack of electrolysis cells is housed in the sealed casing;
• in which the sealed casing includes a case including a base and a cover that are securely attached to one another, wherein the stack of elementary electrolysis cells is assembled between an upper and a lower plate, the lower plate of which is resting on the base of the box through an electrical insulator;
• in which clamping means is fitted at least partly between the upper plate and the cover of the case, wherein the clamping means is configured to provide a determined contact force by compression between the lower plate and upper plate of the stack of cells;
• in which the clamping means includes an additional plate installed with a loose fit in the case and in direct contact with the upper plate, wherein the additional plate is configured to be moved by the steam containing at most 1% hydrogen from outside the case through the cover, wherein movement of the additional plate causes a clamping force between the lower and upper plates, and wherein the fit enables the stack of cells to be supplied at least partially with steam containing at most 1% hydrogen.