Reinforcement of molten carbonate fuel cell matrixes by adding rod-shaped γ-LiAlO₂ particles

Improvement in strength of γ-LiAlO₂ matrixes for a molten carbonate fuel cell (MCFC) via addition of rod-shaped γ-LiAlO₂ particles has been investigated. The rod-shaped γ-LiAlO₂ particles with the aspect ratio of 9-15 were obtained by heat-treating rod-shaped β-LiAlO₂ particles at 800 °C for 3 h, synthesized from the reaction mixture of LiOH-γ-Al₂O₃-NaOH. The γ-form was very stable for more than 700 h in a molten carbonate environment at 650 °C, while the β-form showed both a phase change from β- to γ-LiAlO₂ and a morphology change from rod- to bipyramid-shapes. The average pore size and the porosity of the matrix (550 μm thickness) fabricated by tape-casting of the slurry with weight ratio 1.0 of rod-shaped γ-LiAlO₂ particles to commercial γ-LiAlO₂ powders (2.0 μm dia.) were about 0.12 μm and 54%, respectively, after being heat-treated at 650 °C for 2 h. The strength (197 g_f/mm²) of the rod- shaped particle reinforced matrixes was enhanced more than twice as much as that of the non-reinforced γ-LiAlO₂ matrixes (91 g_f/mm²).