Solid oxide fuel cells rely on electrochemical means for burning hydrogen or fossil fuels or hydrogen, rather than combustion. As an alternative energy technology, solid oxide fuel cells show promise as a versatile power source that can be used in a variety of applications — everything from increasing fuel efficiency in vehicles to serving as a power supply for buildings. And they are more efficient than any practical combustion engine.
So why haven’t they been widely adopted? Cost.
But materials scientists at the University of Wisconsin-Madison have used quantum mechanics-based computational techniques to search for new materials that could operate at lower temperatures, with higher efficiency and longer lifetimes — and be transformative for reducing costs.
Solid oxide fuel cells typically require temperatures around 800 degrees Celsius to operate — such high temperatures cause materials in the cells to degrade quickly, limiting the device's working life. By enabling the cells to operate at a lower temperature, that degradation could be slowed. Longer life, in turn, would lessen the need for cell replacement and increase cost-effectiveness.
The researchers screened more than 2,000 candidates from the perovskite class of compounds, which yielded 52 potential new cathode materials. Their approach also allowed them to codify material design principles that had previously been based on intuition, and to offer suggestions for improving existing materials.
The key was to search for stable compounds with high activity to catalyze the oxygen reduction reaction. Using computational modeling to quantitatively calculate a perovskite’s catalytic activity, however, is prohibitively difficult because of the high complexity of the oxygen reduction reaction. To overcome this challenge, the researchers selected a physical parameter that was more straightforward to calculate, and showed empirically its correlation with the catalytic activity. It could then serve as an effective proxy. Once experimental correlations were established, high-throughput computational tools could be used to effectively screen a large group of materials.
The researchers are collaborating with a group from the National Energy Technology Laboratory (NETL) for testing one of their candidate cathode materials. According to UW-Madison’s Professor Dane Morgan, the project is an example of the sort of advances that are aided by the Materials Genome Initiative — an ongoing national effort focused on accelerating the pace for discovery, development and manufacture of new materials.
The research was also supported by grant from the U.S. Air Force and the National Science Foundation, and was published in a recent issue of the journal Advanced Energy Materials.