A D V A N C E D M A T E R I A L S & P R O C E S S E S | A P R I L 2 0 2 1 9 that suppresses the deterioration brought on by the reduction-oxidation cycle, a major cause of ceramic fuel cell degradation, by significantly reducing the quantity and size of the nickel catalyst in the anode using a thin-film technology. Ceramic fuel cells generally operate at high temperatures—800°C or higher. Therefore, inexpensive catalysts, such as nickel, can be used in these cells, as opposed to low-temperature polymer electrolyte fuel cells, which use expensive platinumcatalysts. 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 that accompany stop-restart cycles, uncontrollable expansion occurs. This results in the destruction of the entire ceramic fuel cell structure. This fatal drawback has prevented the generation of power by ceramic fuel cells from applications that require frequent start-ups. To overcome this challenge, the team developed a new concept for an anode that contains significantly less nickel, just 1/20 of a conventional ceramic fuel cell. This enables the nickel particles in the anode to remain isolated fromoneanother. Tocompensate for the reduced amount of the nickel catalyst, the nickel’s surface area is drastically increased through the realization of an anode structure where nickel nanoparticles are evenly distributed throughout the ceramic matrix using a thin-film deposition process. In ceramic fuel cells using this novel anode, no deterioration or performance degradation of the ceramic fuel cells was observed, 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 conven- tional cells, despite the substantial reduction of the nickel content. www. kaist.ac.kr/en/. Conceptual diagram of the oxidation-reduction cycle of ceramic fuel cells and new concept vs. deterioration rate of conventional fuel plates. Courtesy of Korea Institute of Science and Technology.
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