Abstract: An alkali metal energy conversion device, particularly a sodium sulphur cell has a cylindrical outer casing (18) containing a tubular solid electrolyte (10) of beta alumina. An outer cathode region between the electrolyte (10) and the casing (18) contains sulphur, and an inner anode region in the electrolye tube contains sodium. An alpha alumina lid (12) closes the tube (10) and holds a current collector (15). The cathode region is sealed by an annular metal element (23) which is thermocompression bonded about its inner periphery to the lid (12) and is welded about its outer periphery to the casing (18). A second annular metal element (26) is thermocompression bonded to the lid (12) wholly inside the first annular element (23) and is welded to the current collector.The metal elements (23,26) are bonded to the lid (12) before the lid is glazed to the electrolyte tube (10) and before the first element (23) is welded to the casing (18).

Abstract: An alkali metal energy conversion device, particularly a sodium sulphur cell has a cylindrical outer casing (18) containing a tubular solid electrolyte (10) of beta alumina. An outer cathode region between the electrolyte (10) and the casing (18) contains sulphur, and an inner anode region in the electrolyte tube contains sodium. An alpha alumina lid (12) closes the tube (10) and holds a current collector (15). The cathode region is sealed by an annular metal element (23) which is thermocompression bonded about its inner periphery to the lid (12) and is welded about its outer periphery to the casing (18). A second annular metal element (26) is thermocompression bonded to the lid (12) wholly inside the first annular element (23) and is welded to the current collector.The metal elements (23, 26) are bonded to the lid (12) before the lid is glazed to the electrolyte tube (10) and before the first element (23) is welded to the casing (18).