Görüryilmaz, M. T.; Kemppainen, E.; Dorbandt, I.; Dharmaraj, K.; Schultz, T.; Davis, S.; Zhou, Z.; Koch, N.; Browne, M. P.; Schlatmann, R.; Calnan, S.: Test Procedures for the Evaluation of the Performance and Stability of Direct Ammonia Fuel Cells. Energy Technology 14 (2026), p. e70564/1-21
10.1002/ente.70564
Open Accesn Version
Abstract:
The first comprehensive electrochemical test protocol for probing both steady-state and transient operations of low-temperature direct ammonia fuel cells (DAFCs) is introduced. It combines galvanostatic holds, cyclic staircase loads mimicking start-up/shut-down, long dynamic current loading representative of automotive application, and extended open-circuit periods. A hydrogen reference electrode at the anode inlet enables three-electrode operation, so anode and cathode overpotentials, impedance spectra, and polarization curves can be recorded simultaneously and de-convoluted in real time. DAFCs (25 cm2) with ultralow catalyst loading (0.3 mgPt/cm2) electrodeposited on nickel foam were operated on 1.0 M NH3 + 1.0 M KOH at 60°C. Durability measurements indicate that voltage decay is dominated by reversible anode deactivation driven by fuel depletion; full recovery upon fuel replacement confirms minimal permanent catalyst damage. Impedance analysis indicates that the cathodic double-layer capacitance increases, consistent with flooding. Mass spectrometry identifies N2 as the sole gaseous product at 0.2 V with no detectable NOx. The protocol's ability to identify these phenomena over a single campaign provides an essential tool for future DAFC development. Together, the results establish links between operating regime, fuel utilization, and degradation pathway. They furnish a benchmark for emerging membranes, catalysts, and cell architectures to be compared.