Rejuvenation of Fuel Cells

The deliverable presents the obtained measurement and analysis results of the accelerated stress test protocols consisting of voltage cycling, designed to target electrocatalyst degradation, with the intentional recovery periods (so-called soak time steps) every 2500 voltage cycles on an already conditioned 50 cm2 (single) fuel cell provided by ElringKlinger. Before and after every intentional stop, a series of diagnostic methods (polarization curves, electrochemical impedance spectroscopy, cyclic voltammetry, linear sweep voltammetry) were performed. During the conducted durability test, different shutdown procedures, as well as different duration of the soak time period were tested with their impact on performance recovery phenomenon. The results suggest that cause of the reversible degradation could be accumulated water within the cell and/or presence of oxygen within the catalyst layer. The prolonged soak time step reduces recovery effect, while rapid reduction of the cell temperature with ice proved to be counterproductive for performance recovery. Shutdown procedure without shortly-connected resistor has shown no effect on recovery. Shutdown procedure without nitrogen purge proved to be the most effective for performance recovery.