Durability evaluation of PEM fuel cell components

Sammanfattning: Proton exchange membrane fuel cells (PEMFCs) are used to convert hydrogen and oxygen to electricity, heat, and water. There are no greenhouse gas emissions, given that the hydrogen is produced from renewable sources, such as water electrolysis from wind, hydro or solar energy. PEMFCs can be found on the commercial market today, predominantly in applications such as forklifts, passenger cars and combined heat and power units. The PEMFC is a new technology, and there are hurdles to overcome, mainly with regard to price and durability.In this work, two PEMFC components are the main focus: the bipolar plate and the catalyst. For the bipolar plate, the effect of defects from fabrication is investigated to further understand the critical factors for corrosion and how to avoid it. Droplets from laser cutting and cracks in the coating due to the forming of pre-coated plates are both identified as possible sources of corrosion. However, by correct design, both can be avoided or made less critical. Laser welding stainless steel 304 is, on the other hand, found not to be a source of corrosion under simulated PEMFC bipolar plate conditions. Furthermore, tailoring the properties of a multicomponent alloy coating by additions of Ta and W is explored to stabilise the coating at higher potentials in the acidic environment of the PEMFC. Ta is found to achieve a protective passive layer at a lower concentration than W. However, it does significantly increase the interfacial contact resistance. One-step synthesis of a ternary alloy by electrodeposition is studied for the catalyst to allow for facile screening of new alloy compositions, both in- and ex-situ. The ternary alloy gives comparable results to the binary alloy even at lower Pt content.As the PEMFC has entered the commercial market relatively quickly, there is a lack of standardised tests, both on the component and system level. The procedure for testing the interfacial contact resistance of the bipolar plate is studied in detail, and the methodology is further developed to ensure reliable and comparable results.