Phase and microstructure stabilities of LiAlO2 in molten Li/Na carbonate for molten carbonate fuel cells

Abstract

The phase and microstructure stabilities of LiAlO2 (for improving the matrix reliability of molten carbonate fuel cells are investigated. The phase transformation and particle growth of LiAlO)(2) (are examined via immersion tests of pure g-LiAlO)(2) (an a-/g-LiAlO)(2) (mixture and pure a-LiAlO)(2) (in molten carbonate at 650C in an air atmosphere. Dissolution of Li+ ions occurs mainly from y-LiAlO)(2) (over an 18 000 h period, and the dissolved Li+ ions precipitate as LiNaCO)(3) (and a-LiAlO)(. Particle growth takes place continuously from an early stage of heat-treatment and quickly progresses by the accelerated dissolution and precipitation of Li+ ions after 10000h. By contrast, the particle size and the crystalline phase of a-LiAlO)(2)(2) (do not change during 3000 h of immersion. These results show that a-LiAlO)(2) (is less soluble than g-LiAlO)(2) and is more stable in molten carbonate. 2005 Elsevier B.V. All rights reserved.