Ammonia-reformate-fueled PEMFC anode recirculation using cathode-degraded PEMFCs as electrochemical hydrogen pumps

As renewable energy use grows globally, managing waste from retired or degraded energy devices has become critical, particularly for polymer electrolyte membrane fuel cells (PEMFCs), which require sustainable and efficient recycling solutions. This study proposes a repurposing strategy that converts cathode-degraded PEMFCs directly into electrochemical hydrogen pumps (EHPs) without the need for disassembly, enabling efficient hydrogen recovery and reuse within PEMFC systems using ammonia-derived, post-purified reformate. To validate the feasibility of this approach, an PEMFC anode recirculation system was developed, in which the cathode-degraded PEMFC served as an EHP for off-gas hydrogen recovery. Accelerated stress tests were conducted to induce cathode catalyst degradation, and the performance of the cell was evaluated in both fuel cell (FC) and EHP modes using a segmented cell. In FC mode, the peak power density decreased by 10.6% and 18.2% relative to the initial performance after successive degradation cycles, accompanied by local current density deviations up to 22%. Incorporating a cathode-degraded PEMFC as an EHP increased the maximum system efficiency to 49% at an operating current of 20 A and a fuel utilization of 94%, which was 13 percentage points higher than that without hydrogen recovery, while maintaining a higher hydrogen mole fraction at the anode outlet, which may help mitigate fuel-starvation-related degradation. These findings demonstrate the feasibility of repurposing cathode-degraded PEMFCs as EHPs and provide insights into sustainable strategies for fuel cell reuse and resource circularity.