Fabrication and performance evaluation of electrolyte-combined α-LiAlO2 matrices for molten carbonate fuel cells

To improve the unit cell performance and stability, molten carbonate fuel cell (MCFC) matrices were fabricated using synthetic α-LiAlO2 powder and they showed mechanical and microstructural stability under thermal cycle tests. The pure α-LiAlO2 matrix demonstrated stability with high open-circuit voltage (OCV) and maximum power density during many thermal cycle tests (more than 15 repetitions). Furthermore, to minimize the change in stack height during stack start-up and to improve mechanical and microstructural stabilities of the matrix, the electrolyte-combined α-LiAlO2 matrix was optimized by controlling the mixing ratio of synthetic α-LiAlO2 and Li/K carbonate powders. The suitable electrolyte content was fixed at approximately 50 vol.% for the homogeneously filled pores of the pure α-LiAlO2 matrix. These matrices showed good microstructural stability during five thermal cycle tests in an air atmosphere at 923 K and with improved unit cell performance (0.127 W cm−2) under MCFC operating conditions.In unit cell and thermal cycling tests, the optimized matrices were stable through more than 20 repetitions.

► Slurry compositions of the α-LiAlO2 matrices were optimized using the tape casting. ► The unit cell had a high OCV and cell voltage during 19 thermal cycle tests. ► Electrolyte-combined α-LiAlO2 matrices were fabricated with electrolyte materials for 40–60 vol% of solids. ► The 50 vol% electrolyte-combined α-LiAlO2 matrices exhibited the best unit cell performance.