| dc.description.abstract | The ever-growing global demand for clean and sustainable energy sources has sparked considerable interest in the development of fuel cell technologies. PEMFCs have gained widespread popularity due to their versatile applications, from stationary applications to being a promising alternative to the internal combustion engine. PEMFC converts hydrogen and oxygen to electricity, heat, and water and will significantly accelerate the transition into a hydrogen-based economy. The bipolar plate is an essential element of the proton exchange membrane fuel cell, accounting for 60\% of the overall weight and around 30% of the total cost. Metallic bipolar plates such as stainless steel are popular thanks to their high conductivity. However, the biggest challenge facing PEMFCs in automotive applications is their weight.
In this work, the performance of carbon-coated aluminum bipolar plates as a lightweight alternative to stainless steel is investigated under accelerated stress test conditions. The accelerated stress test designed for this work incorporates load cycling in wet and dry conditions and includes some MEA stress mitigation techniques.
In-situ electrochemical tests, voltage readings, scanning electron microscopy, and ex-situ interfacial contact resistance were used. The aim was to examine the deterioration of the BPPs and MEA to validate the AST. Results showed an increase in the ohmic losses after 1250 cycles in dry/wet conditions. Interfacial contact resistance measurements demonstrated a slight increase in the anode bipolar plates, while the cathode remained unchanged. SEM showed the wearing of the coating mainly on the lands of the anode bipolar plates, while EDS was used to confirm the formation of an oxide later in the same areas. No trace metal contamination was recorded in MEA and GDLs. However, 50 \% of the electrochemically active surface was lost. This indicates that combining the load and hygrothermal cycling increases the degradation of the catalyst later. Further work should focus on testing Aluminium bipolar plates with different coatings under wet/dry cycling and constant load. This would alleviate the MEA degradation and allow for more cycles before the failure of the cell. | |