Fuel cell technology potentially provides clean and efficient energy for stationary and traction applications. A functioning fuel cell, as any other electrochemical device, requires a series of components that provide the key functions of reactant distribution (mass transport), catalytic reactivity, ionic separation, and current collection. To date, however, the efficiency of fuel cell systems remains well below its theoretical maximum due to implementation practices that result in system components that provide the means of delivering the key functions but concurrently increase the polarization of the cell (reduction in voltage due to impedance of current) due to inefficiencies of design.
Recently, incremental improvements to fuel cell design have substantially reduced polarization contributed through component properties; for example, permeable membrane technologies have been developed that provide thinner yet more robust membranes that are of lower resistance, catalyst alloys are being developed that reduce the loading necessary to achieve a given current density, and manufacturing techniques that use stamped metal plates or innovative carbon-manufacturing methods are used to improve the efficiency of the current collection. Improvements to the reactant distribution, however, have focused on flow field design and pressurization of gases. While these techniques sometimes improve the fuel/oxidant utilization, they come at a cost of reduced efficiency (from increased fluid resistance) or increased complexity (from additional components that require installation and their weight and cost).
A well-known means which is used to reduce the effects of mass transport in electrochemical systems is to use the “spinning disk” or “spinning band” technique, in which at least one of the electrodes is rotated at high speed so that concentration gradients which are established due to resistance to mass transport (diffusion) are greatly reduced by hydrodynamically varying the rate at which electroactive species are brought to the outer surface of the diffusion layer. These types of electrodes are typically used normally in liquid media for small single cells. However, in the “spinning disk” type of fuel cell electrode arrangement, the fuel and the oxidizing agent are typically not separately maintained.
Therefore, a spinning electrode fuel cell is needed in which the electrodes of the fuel cell are rotated to reduce adverse effects of resistance to gas diffusion and in which separation between the fuel and oxidizing agent in the fuel cell is maintained. Such a spinning electrode fuel cell would extend the usefulness of the spinning electrode arrangement to liquids and eliminate the predisposition of the system to extreme crossover currents, thus allowing the use of conventional catalysts.