TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Components: The bipolar plate closest to the negative terminal is free of passage openings. The lateral migration of ions is prevented by a physical isolation of the ion-exchange membranes from the thermostatting fluid. The thermostatting fluid is demineralized water circulating in a close circuit. The perimeter of the ion-exchange membranes is located in an intermediate region of the perimetrical sealing gaskets between the edge of the central hollow portion and the circumference of the passage openings. The ion-exchange membranes are isolated from the thermostatting fluid by sealing components located in the intermediate region, optionally comprising ridges or rings. The ion-exchange membranes are provided with passage holes matching the passage openings of the gaskets and having a greater section than the openings, which are isolated from the thermostatting fluid by sealing components located between the edges of the passage holes of the membranes and the passage openings of the gaskets optionally comprising ridges or rings of non-conductive material in form of planar gaskets or O-rings. The rings of non-conductive material consist of a liquid film applied at the moment of assembling the stack and polymerized with a catalyst contained in the liquid film or by UV irradiation or thermal treatment.    TECHNOLOGY FOCUS - METALLURGY - Preferred Materials: The construction material of the metal bipolar plates is stainless steel containing 16-26% chromium, 10-22% nickel, and optionally molybdenum. The stainless steel is AISI 316L and the steel of chromium nickel (CrNi) 2520 series according to DIN.    TECHNOLOGY FOCUS - POLYMERS - Preferred Materials: The rings of non-conductive material are made of low hardness rubbers, optionally ethylene propylene monomer (EPM) or ethylene propylene diene monomer (EPDM). The liquid film consists of a silicone resin-based polymerizable material. The film is provided with elasticity and reduced hardness after polymerization.