Applicability of double layer capacitance measurements to monitor local temperature changes at polymer electrolyte membrane fuel cell cathodes

One of the most sensitive parameters to control the performance of automotive-size polymer electrolyte membrane fuel cells (PEMFCs) is the cell temperature. For instance, when starting up the fuel cell, it is critical to know whether the cell temperature is below ~273 K or, approaches the operating conditions. The easiest way to determine this is to perform measurements using some commercially available temperature sensors at the active electrode surface. However, this only applies to single-cells and not for automotive fuel cell stacks with ~400 cells. In this case, the measurement with a standard resistive temperature sensor is practically problematic. In this paper, we demonstrate that the electric double layer capacitance of the PEMFC cathodes (geometric active area size of 43.6 cm²) increases linearly from 268 K up to 333 K; and using this information, it is possible to determine the catalyst temperature accurately within this temperature range. These results should be of particular significance for both modelling the double layer in the PEMFCs as well as for the practical use in automotive applications.