In this work, a direct ammonia fuel
cell, which consists of an
anion exchange membrane and commercially available PtRu/C and Pd/C
catalysts at the anode and cathode, respectively, is developed. Experimental
results demonstrate that the direct ammonia fuel cell exhibits a peak
power density of 20.7 mW cm–2 and an open-circuit
voltage of 0.67 V at 95 °C when fed with 3.0 M ammonia and 3.0
M KOH. Besides, the durability test results reveal that the developed
direct ammonia fuel cell can maintain stable operation for more than
25 h. In addition, the effects of operating parameters, such as the
concentrations of ammonia and KOH, flow rates of anolyte and oxygen,
and operating temperatures on the cell performance, are experimentally
examined. A higher KOH concentration is observed to increase the cell
voltage by enhancing the kinetics of ammonia oxidation, which is facilitated
by the higher concentration of OH– in the catalyst
layer. However, increasing the KOH concentration leads to higher internal
resistance in the cell as a result of the increased viscosity of the
anolyte. Besides, the analysis of results suggests that a moderate
flow rate of both anolyte and gaseous oxygen can also enhance the
cell performance by reducing ammonia crossover and preventing membrane
dehydration, respectively. Moreover, increasing the operating temperature
of the cell also promotes the kinetics of the electrochemical reactions
at the catalyst layers, which is also associated with an enhanced
mass transfer within the electrodes. In summary, a direct ammonia
fuel cell, using an anion exchange membrane, with relatively high
performance has been developed. The study provides insights into the
performance-enhancing strategies, via operating conditions, toward
the further development of the cell.