An enhanced thin-film resistance temperature detector and its application for catalyst layer surface temperature measurement inside PEMFC

Abstract

Temperature detection is of vital significance for the thermal management of proton exchange membrane fuel cells (PEMFCs). In this work, a robust Au thin-film resistance temperature detector (RTD) was fabricated based on the micro-electro-mechanical system (MEMS) to achieve temperature monitoring inside PEMFC. Low-temperature heat treatment was carried out to promote the performance of RTD, and was confirmed to help achieve good linearity and small thermal hysteresis. Combined with X-ray diffusion (XRD) Rietveld refinement and morphology analysis, particularly the lattice strain and dislocation calculation, low-temperature heat treatment is supposed to help eliminate lattice defects and residual strains in the film. Subsequently, this prepared RTD was applied to measure cathode catalyst layer (CCL) temperature inside PEMFC under different relative humidity (RH) and current loads. The results show that current loads are positively related to temperature variation. The higher the current, the more Joule and irreversible heat are generated. The RH of anode and cathode has a more complex impact on temperature evolution, depending on the water concentration in the electrode sites, which is not only affected by RH, but also by the oxygen reduction reaction (ORR). Too high water contents in the electrode area would bring about flooding, while too low would result in membrane drying, so both of them cause different levels of ohmic and mass transport loss, hence inducing temperature variations. This work is supposed to benefit the research of RTD enhancement and thermal state inside PEMFC.