Investigation of self-humidified and dead-ended anode proton exchange membrane fuel cell performance using electrochemical impedance spectroscopy

Self-humidified dead-ended anode proton exchange membrane fuel cell is increasingly being used in some special applications due to its need for simpler and lower cost subsystems. However, the performance of such a fuel cell is more affected by the operational parameters and conditions than the traditional proton exchange membrane fuel cells. Therefore, realizing the most effective parameters and determining their optimum values are essential. In the present study, electrochemical impedance spectroscopy is used to examine the effect of working conditions on the performance of a self-humidified dead-ended anode fuel cell. Working temperature, air stoichiometry, and purge interval are selected to assess their effects on the fuel cell performance. The results show that the performance enhances by increasing the working temperature up to 50 °C, but further increase of the temperature causes an intense reduction in the performance due to a combination of severe membrane drying and build-up of nitrogen in the anode side. The impedance spectra are greatly influenced by the air stoichiometry since increasing the air stoichiometry may lead to severe membrane drying in one hand and increasing mass transport resistance due to accumulation of N2 in the anode side, on the other hand. While the impedance spectra are less affected by the purge interval at its low values, large values of the purge interval lead to significant mass transport issues. Wasted electrical energy and wasted energy due to hydrogen purging are calculated and compared at different purge intervals.