Synthesis of fine particle size lithium aluminate for application in molten carbonate fuel cells

Abstract

Lithium aluminate (LiAlO 2) was synthesized by heat treatment of various types of aluminas (γAl 2O 3, αAl 2O 3, γAlOOH, and Al (OH) 3), Li 2CO 3 or LiOH, and Li 2CO 3K 2CO 3. For this procedure, the temperature (625 to 975 K) and time (1.5 to 90 h) of heat treatment were varied to determine the optimum conditions to obtain γLiAlO 2 of high surface area, which was suitable for electrolyte structures in molten carbonate fuel cells. A mixture of Li 2CO 3K 2CO 3 and high-surface area γLiAlO 2 was obtained by the heat treatment of γAl 2O 3, LiOH, and Li 2CO 3K 2CO 3 at 775 K for 2 h, then at 975 K for 16 h. However, when γAlOOH, Al (OH) 3, and αAl 2O 3 were substituted for γAl 2O 3 in the synthesis procedure, α, β, and γLiAlO 2 were obtained. A mixture of Li 2CO 3K 2CO 3 and a major phase of αLiAlO 2 was obtained by heat treatment of alumina, Li 2CO 3, and Li 2CO 3K 2CO 3 at 875 to 975 K for 23 to 90 h; this material is not suitable for electrolyte structures.