Trace Metals Improve Fuel Cell Stability
Trace Metals Improve Fuel Cell Stability
Scientists in South Korea have used doped electrode materials with small
amounts of metal to improve the chemical stability of fuel cells.
AsianScientist (Jan. 26, 2018) – Scientists in South Korea have devised
a method to improve the chemical stability of electrode materials by
introducing trace amounts of metal. They published their findings in the
journal Energy & Environmental Science. Fuel cells are emerging as
eco-friendly and renewable energy sources. In particular, solid oxide fuel
cells made of ceramic materials have been gaining attention for their ability
to directly convert various forms of fuel—such as biomass and liquid natural
gas into electric energy.
The core factor that determines the performance of solid oxide fuel
cells is the cathode at which the reduction reaction of oxygen occurs.
Conventionally, oxides of perovskite are used in cathodes. However, despite the
high performance of perovskite oxides at initial operation, the performance
decreases with time, limiting their long-term use.
In particular, the high temperature oxidation state required for cathode
operation leads to a phenomenon known as surface segregation, in which
strontium oxide accumulates on the surface of the perovskite oxides, resulting
in decreased electrode performance. The detailed mechanism of this phenomenon
remains unclear, and a way to effectively inhibit it has not been suggested. In
this study, a team of researchers led by Professor Jung WooChul at the Korea
Advanced Institute of Science and Technology (KAIST) in South Korea used
computational chemistry and experimental data to determine the parameters
affecting surface aggregation.
They observed that local compressive states around the strontium atoms
in a perovskite electrode lattice weakened the Sr-O bond strength, which in
turn promoted strontium segregation. The team identified local changes in
strain distribution in perovskite oxide as the main cause of segregation on
strontium surface. Based on these findings, the team doped the oxides with a
variety of metals to control the extent of lattice strain, effectively inhibiting
strontium segregation.
“This technology can be implemented by adding a small amount of metal
atoms during material synthesis, without any additional process,” said Jung. “I
hope this technology will be useful in developing highly durable perovskite
oxide electrodes in the future
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