Fuel cells used in hydrogen vehicles has shown that when they are initiated or brought to a sudden halt (start-up/shut-down, SU/SD), external air is drawn into the vehicle. The oxygen present in this air triggers an unintended electrochemical reaction within the fuel cell, expediting the deterioration of the catalyst. Given the nature of driving conditions, frequent SU/SD occurrences are inevitable, resulting in significant catalyst degradation.
Professor Yong-Tae Kim from the Department of Materials Science and Engineering and the Graduate Institute of Ferrous & Eco Materials Technology and along with Sang-Hoon You, a doctoral candidate in the Department of Materials Science and Engineering at Pohang University of Science and Technology (POSTECH), have applied a layer of tungsten oxide (WO3) to the membrane-electrode assembly(MEA), a crucial component of hydrogen fuel cells. This innovation aims to enhance the performance and efficiency of the electrode.
The team harnessed the concept of metal-insulator transition (MIT) to tackle this challenge. MIT is a phenomenon wherein an insulator becomes capable of conducting electricity when subjected to external factors like changes in the concentration or temperature of an ambient gas. WO3 (tungsten oxide) possesses the unique property of selectively conducting electricity as protons are intercalated/deintercalated by exploiting the MIT phenomenon.
To address the issue, the team applied a coating of WO3 to the catalyst layer at the anode of the MEA. Under normal operational circumstances, this coating maintains electrical conductivity. However, it selectively obstructs current flow exclusively during start-up/shut-down (SU/SD) conditions, preventing electrochemical reactions that lead to catalyst corrosion.
When the MEA coated with WO3 was incorporated into an actual fuel cell, the catalyst remained corrosion-free during SU/SD events, exhibiting an impressive performance retention rate of 94%. The team’s technology, involving the application of WO3 to the MEA, not only enhances the cell’s durability but also offers the advantage of integration into the existing mass production process for MEAs.
Professor Yong-Tae Kim remarked, “This innovation will directly and significantly contribute to enhancing the durability of commercial hydrogen fuel cell vehicles.” He added, “What’s more, it can be readily applied to mass production processes of MEAs, simplifying its practical implementation.”
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This tech could prove to be a major milestone in commercial fuel cell development progress. With many efforts underway to get fuel cells consumer ready, this work is likely to see quite a large rate of adoption and further experimentation.
The development efforts aren’t making big news out of discoveries that hold the fuel cell tech back, so we aren’t getting a clear picture of what’s in the way. Most improvements are likely to be proprietary and patented. Time will tell, but the efficiency of fuel cells is outstanding, something that simply can not be overlooked – so progress will come.
But the problem fuel cells and all hydrogen based power systems have is the hydrogen storage.
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For that, the full solution to make hydrogen a dominant fuel is yet to be found. We may have a spectacular fuel cell technology first, which will intensify the storage effort even stronger.
By Brian Westenhaus via New Energy and Fuel
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