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How do catalysts in fuel cells age and why is this important for our environment?

Picture by Akitada31

Publish Date: 10.11.2021

Category: Interdisciplinary research, Our contribution to sustainable development goals

Sustainable development goals: 7 Affordable and clean energy, 9 Industry, innovation and infrastructure, 11 Sustainable cities and communities, 12 Responsible consumption and production, 13 Climate action, 17 Partnerships for the goals (Indicators)

Hydrogen fuel cells with proton exchange membrane are one of the key technologies of hydrogen economy and the de-fossilization of long-distance heavy-duty transport. Therefore, they contribute significantly to achieving climate neutrality and a toxic-free environment, which are important objectives of the European Green Deal. Hydrogen fuel cells enable direct transformation of chemical energy released by the reaction between hydrogen and oxygen into electrical energy, with water being the only side product. The catalyst is a crucial fuel cell component for ensuring fast and efficient dissociation reaction of hydrogen into two protons and two electrons, and subsequent recombination of oxygen, hydrogen and electrons into water molecules with minimal voltage drop of the fuel cell. The catalyst layer usually consists of platinum nanoparticles dispersed on the surface of a highly porous carbon support. Due to the high price of platinum, the catalyst has a significant impact on the price of the fuel cell and its environmental footprint.

One of the main research challenges is to reduce the price of fuel cells while optimising their performance and ensuring their expected lifetime under the envisaged operating conditions. Due to the complex interactions of chemical and physical degradation mechanisms that take place in fuel cells, these goals can only be achieved through a better understanding of these processes, which can be efficiently supported by mathematical-physical models. Researchers at the Laboratory for Internal Combustion engines and Electromobility (LICeM) at the University of Ljubljana, Faculty of Mechanical Engineering have systematically addressed this challenge by developing a framework for coupled modelling of fuel cell operation and degradation, which enables a consistent description of the entire causal chain from impact of operating conditions on degradation processes to their back influence on fuel cell operation.

In the recent paper, published in the renowned Journal of Power Sources in collaboration with researchers from the National Institute of Chemistry, Department of Materials Chemistry, they presented an experimentally verified mathematical-physical model for analysing and predicting the degradation of platinum catalysts in fuel cells. The model describes catalyst degradation caused by the growth of platinum nanoparticles due to two different processes, dissolution and redeposition, and agglomeration due to corrosion of the particle support. As the first model of its kind, the developed model consistently describes the influence of temperature on each of the degradation mechanisms, which greatly enhances its predictive capabilities. The model thus provides a better understanding of the interrelationship between fuel cell operating conditions and degradation mechanisms, which is crucial for the further development of more resilient catalyst materials and the elaboration of less detrimental operating protocols, which allow to extend their lifespan.

Strojna f. Slika1Schematic overview of modelled electrochemical mechanisms (a), which cause dissolution (b) and agglomeration (c) of platinum nanoparticles, leading to the loss of catalyst surface (d). Source 

The model represents a significant extension of the existing modelling framework for simulating coupled operation and degradation of fuel cells, which also includes a model for simulating membrane degradation. The latter model was developed within the framework of the international project SoH4PEM - State-of-health observers for PEM fuel cells, founded by the FFG (Austrian Research Promotion Agency). The importance and relevance of the research carried out in the field of fuel cell degradation modelling and the efficiency of the transfer of research results into advanced technological products is further confirmed by the integration of the developed modelling framework into the commercial simulation platform of one of the leading companies and its subsequent use in the development process of fuel cell based systems at leading automotive manufacturers. These references also positioned the LICeM as a leading partner responsible for fuel cell modelling in a recently launched research project MoreLife - Material, Operating strategy and REliability optimisation for LIFEtime improvements in heavy duty trucks founded by Fuel Cells and Hydrogen Joint Undertaking (FCH JU).


strojna Slika 2

 Schematic overview of coupling between hydrogen fuel cell operation and catalyst degradation model. Source



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