Current Mapping of a Diagnostic Modeling Cell

Uniformity of current density across the entire active area of the electrode is crucial to the optimization of the cell performance. A non-uniform current density distribution can cause reduced reactant and catalyst utilization, limited energy efficiency, and decreased lifetime of the cell. Determination of current density distribution is vital for designing PEM fuel cells that achieve higher performance and longer life. The common current mapping techniques, such as sub-cell approach, partial MEA, and segmented current collector and flow field, are simple to perform but often compromise the normal design and operation of the fuel cell. By comparison, local current mapping by micro-thermocouples are easier to set up and can be done without disturbing the operation of the fuel cell, which opens the possibility for carrying out in situ measurements in real practical applications under various conditions. The main objective of this report is to present a simple method of measuring the temperature distribution of a diagnostic modeling cell with micro-thermocouples and relate this to current density distribution of the cell. For this purpose, the diagnostic modeling cell with an active area of 192 cm2, which incorporates the desired measurements and aims at supplying parameters to computer models, was designed and built. Altogether 18 thermocouples were embedded into the anode plate using epoxy. The temperature ramp of the diagnostic modeling cell was recorded once operation under load began for each condition, as shown in Figure 1