Researchers at Kyushu University have developed solid oxidized fuel cells (SOFCs) with high proton conductivity at 300°C to help them move away from fossil fuels.
As global energy demand increases, researchers, industry, governments and stakeholders are working together to develop new ways to meet that demand.
Solid oxidized fuels are promising due to their high efficiency and long life, but one major drawback is that they need to operate at high temperatures of around 700-800°C. Therefore, the utility of these devices requires expensive heat-resistant materials.
Currently, researchers at Kyushu University report that they have successfully developed a new SOFC with an efficient operating temperature of 300°C.
The team hopes that the new findings will lead to the development of low-cost, low-temperature solid oxidized fuel cells, significantly accelerating the practical applications of these devices.
How do solid oxidized fuels work?
Unlike batteries that emit stored chemical energy as electricity, fuel cells convert chemical fuels directly into electricity and continue to do so as long as the fuel is provided.
The heart of a SOFC is an electrolyte, a ceramic layer that carries charged particles between two electrodes.
In hydrogen fuel cells, electrolytes transport hydrogen ions (also known as protons) to generate energy. However, fuel cells must operate at very high temperatures to operate efficiently.
“Reducing the working temperature to 300°C reduces material costs and opens the door to consumer-level systems,” explained Professor Yoshihiro Yamazaki, Kyoto University’s interdisciplinary energy research platform, which led the research.
“However, known ceramics could not carry enough protons to speed up in such “warm” conditions. So we set out to break that bottleneck. ”
Change the physical properties of the material
Researchers have investigated various combinations of materials and chemical dopants. This can alter the physical properties of solid oxide fuel cells. This increases the speed at which protons pass through the electrolyte.
Yamazaki said: “Addition of chemical dopants can increase the number of mobile protons passing through the electrolyte, but it usually clogs the crystal lattice and slows the protons.
“We looked for a free-moving oxide crystal that houses many protons and can move. The balance that has finally hit new research.”
The team found that doping with a high concentration of scandium (SC) allows two compounds, barium stunnert (BASNO3) and barium titanate (BATIO3), to achieve SOFC benchmark proton conductivity of 0.01 S/cm or more at 300°C.
“The data on lattice dynamics reveal that basno and batio are essentially “softer” than traditional SOFC materials, absorbing much more SC than previously assumed,” Yamazaki said.
Long-term applications for decarbonization
The findings reverse the trade-off between dopant levels and ion transport and provide a clear pathway for low-cost, intermediate-temperature solid oxidation fuel cells.
Yamazaki concluded: “Beyond fuel cells, the same principles can be applied to other technologies, such as cryo-electrolytic agents, hydrogen pumps, and nuclear reactors that convert Co into valuable chemicals.
“Our work transforms long-standing scientific paradoxes into practical solutions, bringing affordable hydrogen power closer to everyday life.”
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