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Abstract:
This paper critically evaluates the current state-of-the-art material, LiAlO2, used in the matrices of molten carbonate fuel cells (MCFC) and explores alternative material solutions to extend their operational lifetime and efficiency. Despite its prevalent use due to high stability and corrosion resistance, LiAlO2 fails to meet the long-term operational demands of MCFCs. This study extends the discourse beyond the conventional LiAlO2/K2CO3: Li2CO3 system, proposing optimizations in matrix structures through the integration of various material-matrix solutions. We delve into the fundamental aspects influencing matrix strength, including particle size, surface tension, and thermal expansion coefficients, to understand their impact on the mechanical integrity and functionality of the matrix in highly corrosive environments. Theoretical insights and experimental validations are presented to support the feasibility of alternative materials in enhancing MCFC performance. This paper not only contributes to the material science field by addressing the limitations of current MCFC technologies but also opens new avenues for the development of more robust and efficient fuel cell systems.

Keywords:
Molten carbonate fuel cells (MCFC), LiAlO2 matrix, Material optimization, Surface tension, Thermal expansion coefficients, Mechanical strength

Abstract:
Considerable efforts have been made in recent years to assess the mechanical strength of the matrix in molten carbonate fuel cells (MCFCs), however most studies have been limited to room-temperature testing. This paper introduces methodologies for measuring the compressive strength of the matrix at operational temperatures of 650 °C. The investigation focuses on the fundamental properties of matrices made from different ceramic powders, such as lithium aluminide, aluminium oxide, and yttria-stabilized zirconia (YSZ), which have various powder morphologies. The experimental results were combined with theoretical predictions derived from the classical Young–Laplace law to quantify capillary forces. The findings demonstrate the significant influence of carbonates on the mechanical integrity of the matrix and suggest that structural damage predominantly occurs during assembly or startup of the MCFC. The results show that the morphology of the powder, including particle size and shape, are the key factors reflecting in the final stress-strain response of the matrix. This approach highlights the objective of the present work, which was to integrate the pressureless infiltration of the fabricated porous ceramic pellets with a eutectic carbonate mixture of Li2/K2CO3 and the uniaxial compression at an operating temperature of 650 °C, thereby mimicking the operational conditions of an MCFC.

Keywords:
Molten Carbonate Fuel Cells (MCFC), Ceramic matrices, Compressive strength, Capillary forces