High Stability/Catalytic Activity Co-based Perovskite as SOFC Anode:In-situ Preparation by Fuel Reducing Method
Taking inspiration from the in-situ reduction technique employed for exsolved nano-metal as anodes in solid oxide fuel cells(SOFCs),this study utilized Sr2V0.1Co0.9MoO6,which was synthesized in an ambient air environment,with perovskites of other phases to co-fire with the electrolyte under atmospheric conditions for direct fabrication of a single cell.By this way,the procedure of subjecting the cell to harsh preparative conditions in a reducing/inert atmosphere to prevent its anodic oxidation can be circumvented.After preparation of the anode precursor on the electrolyte sheet,we adopted a simple process of in-situ reduction at 750℃for 4 h on the fuel side to achieve formation of a pure phase Sr2V0.1Co0.9MoO6(R-SVCMO)as anode.The results demonstrate a significant reduction in the activation energy of R-SVCMO,accompanied by an increase in conductivity from 2.7 to 21.6 S.cm-1.Moreover,when employing R-SVCMO as anode in a single cell with H2 and wet CH4 as fuel gases,the maximum power density(Pmax)at 850℃can reach up to 862 and 514 mW·cm-2,respectively,showcasing exceptional catalytic performance.The anodes before and after reduction exhibit average thermal expansion coefficient(TEC)of 1.15×10-5 and 1.23×10-5 K-1,respectively,within the temperature range of 100-850℃,comparable to those observed in conventional SOFC electrolytes.Therefore,the reduction process does not induce any volumetric changes in the anode layer,significantly enhancing its structural stability.Meanwhile,degradation rate of only 0.13%is occurred.It is worth noting that this R-SVCMO synthesis method can result in remarkable long-term stability and high catalytic activity as an anode material.The obtained R-SVCMO can achieve a 60%catalytic efficiency for wet CH4 and last for 1450 h.Based on this R-SVCMO,the single cell can maintain stability for 450 h at 0.7 V.In conclusion,this study demonstrates an effective way of employing an in-situ fuel reduction method to prepare a single cell with exceptional electrochemical performance and structural stability.
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