Small fuel cell system with cartridges for controlled hydrogen generation

Galvanic cells are investigated which can be used as a hydrogen source for small fuel cell systems. Hydrogen is produced by the reaction of zinc and water in a cell which consist of zinc powder as negative electrode and a hydrogen evolution cathode in form of a gas diffusion electrode. In comparison to a zinc air primary battery the KOH electrolyte contains additional water and the ingress of oxygen is prevented. Therefore, the large energy density of the zinc air battery can be maintained to a great extend while the life time of the system is considerably higher. This is achieved by complete separation of the cell from ambient air. Based on the material improvements of Zn powders and separation membranes demountable cells of 70 Ah capacity were designed and tested in combination with micro fuel cells. A control algorithm for the hydrogen generation rate were developed and tested, to achieve stable fuel cell performance at lowest possible hydrogen consumption. The system can be miniaturized and is well suited for mobile and portable power supplies.