Influence of the active area shape on the performance of an open-cathode proton exchange membrane fuel cell stack

Two open-cathode proton exchange membrane fuel cell stacks with similar active area but different shape are developed to evaluate the influence of this parameter on their temperature and performance. A higher height (perpendicular to the air flow) and shorter length (parallel to the air flow) of the active area results in a more efficient heat removal leading to lower temperatures. This leads to an increase in the maximum current density and power output of the stack. With a 5.0 × 5.0 cm 2 stack, stable operation is achieved until 0.5 A cm −2 . An 8.5 × 3.0 cm 2 stack is stable until 0.8 A cm −2 . This effect is more noticeable for longer operation times. High frequency resistance tests reveal reduced ohmic resistances at lower temperatures, suggesting a better humidification of the stack membranes. The effect of the active area shape is also evaluated in the dynamic performance of the stacks. • PEMFC stacks with different active area shapes were studied. • The active area shape has a significant impact on the stack temperature. • Differences in temperature affect the ohmic resistances measured by EIS. • An elongated stack has a higher power output and stability than a quadratic one. • Differences between stacks are more pronounced for longer periods of operation.