KIST, KAIST team develops SOFC anode that addresses problem with intermittent operation; potential applications for mobility
High-temperature solid oxide fuel cells (SOFCs) are very efficient for the direct conversion of chemical fuels to electricity. Inexpensive catalysts, such as nickel, can be used in these cells, as opposed to low-temperature polymer electrolyte fuel cells, which use expensive platinum catalysts. Nickel usually comprises approximately 40% of the anode volume of a ceramic fuel cell.
However, since nickel agglomerates at high temperatures, when the ceramic fuel cell is exposed to the oxidation and reduction processes which accompany stop-restart cycles, uncontrollable expansion occurs. Repeated on and off switching induces reduction–oxidation (redox) cycles at the anode, causing catastrophic failure of the SOFC cell. This limits the use of SOFCs in use cases with intermittent operation.
Now, a team led by Dr. Ji-Won Son at the Korea Institute of Science and Technology (KIST) Center for Energy Materials Research, through joint research with Professor Seung Min Han at the Korea Advanced Institute of Science and Technology (KAIST), has developed a new anode that suppresses the deterioration brought on by the reduction-oxidation cycle by significantly reducing the quantity and size of the nickel catalyst in the anode by using a thin-film technology. The research results were published in Acta Materialia.
Ni content was reduced to 2 vol%, and nanosized Ni particles were uniformly dispersed in a mixed ionic-electronic conducting matrix comprising gadolinium-doped ceria (GDC) using a thin-film technique. Remarkable stability with no performance deterioration even after 100 reduction-oxidation cycles could be observed for the optimized nanostructured anodes. Cell performance at 500 °C was enhanced, exceeding 650 mW/cm2.—Park et al.
Conceptual diagram of oxidation-reduction cycle of ceramic fuel cells and comparison of new concept vs. deterioration rate of conventional fuel plates. Credit: Korea Institute of Science and Technology (KIST)
Dr. Ji-Won Son’s team at KIST developed a new concept for an anode which contains significantly less nickel—1/20 that of a conventional SOFC. This reduced amount of nickel enables the nickel particles in the anode to remain isolated from one another.
To compensate for the reduced amount of the nickel catalyst, the nickel’s surface area is increased significantly through the realization of an anode structure in which nickel nanoparticles are evenly distributed throughout the ceramic matrix using a thin-film deposition process.
Schematic of design and fabrication processes for proposed anode. Credit: Korea Institute of Science and Technology (KIST)
In ceramic fuel cells utilizing this novel anode, no deterioration or performance degradation of the ceramic fuel cells was witnessed, even after more than 100 reduction-oxidation cycles, in comparison with conventional ceramic fuel cells, which failed after fewer than 20 cycles.
Moreover, the power output of the novel anode ceramic fuel cells was improved by 1.5 times compared to conventional cells, despite the substantial reduction of the nickel content.
The potential to apply these ceramic fuel cells to fields other than power plants, such as for mobility, is tremendous.—Dr. Son
This study was financially supported through the Global Frontier Center for Multiscale Energy Systems R&D Program, an Institutional Research Project by KIST, and the Ministry of Science and ICT (MSIT) Midcareer Researcher Project.
Jung Hoon Park, Jong-Ho Lee, Kyung Joong Yoon, Hyoungchul Kim, Ho-Il Ji, Sungeun Yang, Sangbaek Park, Seung Min Han, Ji-Won Son (2021) “A nanoarchitectured cermet composite with extremely low Ni content for stable high-performance solid oxide fuel cells,” Acta Materialia, Volume 206, doi: 10.1016/j.actamat.2020.116580