Hydrogen–Air Fuel Cells with Open Cathode for High-Rate Electric Energy Systems

The results of R&D of electrochemical components of an energy system based on hydrogen–air open cathode fuel cells with proton-exchange membrane are presented. The scheme is shown being capable of realizing electrical power system with high specific energies (up to 700 W h/kg) on the condition that it contains no humidifiers and heaters, light metals are used as the material of bipolar plates, and the fuel cell operates in the mode of self-humidification of the membrane using only the reaction water therefor. Under these conditions, at operating temperatures up to 50°C, the air consumption is 50–100 times higher than the stoichiometric value; there appears a danger of the membrane drying-out. To improve the current–voltage characteristics, a combined method of manufacturing membrane–electrode assembles is used, according to which the catalytic layer was applied by screen printing, and the membrane is formed by direct application of an ionomer to the electrode. The properties of C–Pt- and TiN-based protective coatings on the surface of a titanium bipolar plate are also investigated. The dynamics of changes in the potentials of the electrodes is investigated at “critical” modes of the fuel cell operation and the process stabilization at the nominal mode. Using the experimental data for a fuel cell stack with a power of 1.2 kW and the specific enthalpy–temperature–air humidity diagram, the fuel-cell-operating temperature limits are calculated, at which the process of the membrane self-humidification with reaction water is maintained. The improving of electrochemical components of an open-cathode fuel cell stack is shown to allow achieving a specific power of the power modulus as high as 1 kW/kg.