Researchers at the Korea Institute of Science and Technology (KIST) have developed a high-performance, thin-film-based solid oxide fuel cell that can operate at mid-to-low temperatures below 600 °C using butane fuels.

Since butane can be liquified and thus can be stored and carried easily, the new technology could expand the application range of solid oxide fuel cells to portable and mobile applications such as electric cars, robots and drones. A paper on their work is published in the journal Applied Catalysis B: Environmental.

Previously, ceramic fuel cells had only been considered for application to large-capacity power generation systems due to their high-temperature operation.

When the nickel catalyst of ceramic fuel cells is used with hydrocarbon fuels, such as methane, propane, and butane, the carbon generated during fuel conversion is deposited on the surface of nickel. This worsens seriously as the temperature lowers, leading to the failure of the cell operation. The KIST team solved this problem by incorporating high-performance secondary catalysts, which can convert fuels more easily, by thin-film technology.
Using alternating deposition of the secondary catalyst and the main catalyst layers, the team was able to effectively distribute the secondary catalyst at the nearliest parts of the fuel electrodes to the electrolyte. By this way, controlled incorporation of small amount but effectively positioned secondary catalysts was possible. Using this procedure, the KIST research team was able to successfully apply secondary catalysts known for their high catalytic activity at low temperatures, such as palladium (Pd), ruthenium (Ru), and copper (Cu), to the nano-structure fuel electrodes. Credit: Korea Institute of Science and Technology (KIST)

Ceramic fuel cells typically operate at above 800 ˚C. This high temperature allows the use of inexpensive catalysts, such as nickel, in contrast to low-temperature fuel cells, such as polymer electrolyte fuel cells, which use high-priced platinum catalysts to supplement their low catalytic activity.

Another major advantage of high-temperature fuel cells is that they can use various fuels other than pure hydrogen—such as LPG and LNG—with low emissions due to high efficiency. However, even though high-temperature fuel cells use inexpensive catalysts, their operation requires expensive refractory materials and manufacturing technologies.

Another limiting factor is that their system on-off process takes a long time due to the characteristics of high-temperature operation, which restrict their application to large-scale stationary power generation systems.

Researchers around the world have worked on thin-film-based ceramic fuel cells, which can operate at lower temperatures without performance loss. Unfortunately, the problem has been that lower-temperature operation causes ceramic fuel cells to lose one of their important advantages—the ability to use various fuels. When the nickel catalyst of ceramic fuel cells is used with hydrocarbon fuels, such as methane, propane, and butane, the carbon generated during fuel conversion is deposited on the surface of nickel. This worsens seriously as the temperature lowers, leading to the failure of the cell operation.

Dr. Son Ji-Won’s research team at KIST’s Center for Energy Materials Research research team solved this problem by incorporating high-performance secondary catalysts, which can convert fuels more easily, by thin-film technology. Using alternating deposition of the secondary catalyst and the main catalyst layers, the team was able to effectively distribute the secondary catalyst at the nearliest parts of the fuel electrodes to the electrolyte. This way, controlled incorporation of small amount but effectively positioned secondary catalysts was possible.

Using this procedure, the KIST research team was able successfully to apply secondary catalysts known for their high catalytic activity at low temperatures, such as palladium (Pd), ruthenium (Ru), and copper (Cu), to the nano-structure fuel electrodes.

They confirmed the high-performance operation of the newly developed thin-film-based ceramic fuel cells at mid and low operation temperatures (500-600 ˚C), using butane fuel—a very affordable fuel.

Resources

• Cam-Anh Thieu, Sungeun Yang, Ho-Il Ji, Hyoungchul Kim, Kyung Joong Yoon, Jong-Ho Lee, Ji-Won Son (2020) “Effect of secondary metal catalysts on butane internal steam reforming operation of thin-film solid oxide fuel cells at 500–600 °C,” Applied Catalysis B: Environmental doi: 10.1016/j.apcatb.2019.118349