Mechanical strength improvement of aluminum foam-reinforced matrix for molten carbonate fuel cells

During the cell operation of molten carbonate fuel cells (MCFCs), matrix cracks caused by poor mechanical strength accelerate cell performance degradation. Therefore, for a stable long-term cell operation, the improvement of mechanical properties of matrix is highly required. In this study, aluminum foam was used to enhance the mechanical strength of the matrix as a 3D (three dimensional) support structure. Unlikely conventional matrix (pure α-LiAlO₂ matrix) which has paste-like structure at the MCFC operating temperature, Al foam-reinforced α-LiAlO₂ matrix has significantly strong mechanical strength because the 3D network structure of Al foam can form the harden alumina skin layer during a cell operation. As a result, the mechanical strength of the Al foam-reinforced α-LiAlO₂ matrix was enhanced by 9 times higher than the pure α-LiAlO₂ matrix in a 3-point bending test. In addition, thermal cycle test showed notable cell stability due to strong mechanical strength of Al foam-reinforced α-LiAlO₂ matrix. The Al foam-reinforced α-LiAlO₂ matrix shows appropriate microstructure to preserve the liquid electrolyte when performing the mercury porosimeter analysis and differential pressure test between anode and cathode. Moreover, evaluation of stability and durability for a long-term cell operation were demonstrated by single cell test for 1,000 h.