Hydrogen fuel cells are a promising candidate to replace internal combustion engines, especially for heavy-duty vehicles like long-haul trucks and forklifts. Rather than burning fuel, the hydrogen reacts with oxygen to produce electricity much like a battery, while creating no carbon dioxide emissions.
But as the fuel cells operate, they get contaminated by tiny, positively-charged particles of metal – also known as metal cations – that can degrade their performance. These particles can come from anywhere – impurities in the hydrogen, degradation of metal parts of the cell, or even the air – and they are “bad news,” says ChungHyuk Lee, a chemical engineer at Toronto Metropolitan University.
“They accumulate in the catalyst layers of the cell, and get in the way of the chemical reaction,” he says.
To figure out how exactly these cations behave in a fuel cell, Lee and his colleagues added cobalt ions to a fuel cell and used the ultrabright light of the Canadian Light Source (CLS) at the University of Saskatchewan to track their movement through a simplified version of a fuel cell. Using the BioXAS beamline at the CLS was critical for the experiment, said Lee, because the cations move so quickly that no other device is fast enough to record their movement.
They used those measurements collected at CLS to build a mathematical model to predict how far and how fast they would travel in a real cell under different conditions.
They found that the cations were particularly mobile under more humid conditions, which are common in fuel cells and thus make it more difficult to control the contaminants. And they tended to get stuck within the thin but “twisty and tortuous” catalyst layers, where they interfere with the reactions that produce electricity.
Read more on CLS website