NOVELTY - The foil (8) is arranged in a sealing electrolyte matrix plate (7) on which electrodes (2,3) abut on either side. Support plates (10,11) supporting the electrodes are provided close to gas supply openings in the matrix plate. The foil extends over the transition (14,15) between the support plates and the electrodes.    USE - For electrochemical cells.    ADVANTAGE - Since the foil is not extended over the entire cell surface and is applied only locally, a higher pressure is generated locally. Therefore, a certain degree of compression is produced in the matrix and hence cracking in the matrix at high temperatures during operation of the electrochemical cell is reduced or eliminated. Noble metals are used as the foil material for high temperature operation in the electrochemical cell but plastics materials are used if operating at relatively low temperatures. Since the electrode-support plate transition area is arranged on either side of the matrix plate offset with respect to one another and perpendicular to the matrix plate, local high stress concentration does not arise in the matrix and hence cracking of the matrix plate is prevented. The adaptability of the construction of the electrochemical cell is increased by making one or both gas distribution elements offset with respect to the electrode current collector assembly. Since the risk of the occurrence of fracture in the matrix during the warm-up phase of the cell from the green state to approximately 650 degrees C, is reduced, the gas leakage caused by fracture is completely prevented by the presence of the foil.    DETAILED DESCRIPTION - The matrix plate provides a seal in operation and is delimited on either side by the cathode and the anode and a gas distribution device (4,5) enclosed between separator plates. The gas supply openings in the matrix are provided in a direction perpendicular to the matrix plate. The foil seals the transition area between the support plates and the electrodes. The foil is arranged at least partially in contact with the matrix plate and between the support plate and electrode. The foil comprises a semi-noble metal or a stainless steel coated with an aluminum-containing layer. The foil thickness is between 0.05-0.6 mm, and the foil length is between 5 and 21 mm. The total thickness of the matrix and the foil at the transition area is not more than 30% thicker than the rest of the matrix. By applying the foil in the matrix, a certain degree of compression is produced in the matrix. The compression is achieved if at least 50% of the thickness of the foil is taken up in the surrounding matrix material.    DESCRIPTION OF DRAWING(S) - The figure shows the expanded view of a portion of an electrochemical cell.    electrodes (2,3)    gas distribution device (4,5)    matrix plate (7)    foil (8)    support plates (10,11)    transition (14,15)