Mechanism of Crystal Growth of Lithium Aluminate Particles in Molten Lithium and Potassium Carbonates

Abstract

The growth of particles of lithium aluminate in the electrolyte matrix of molten carbonate fuel cells is problematic in that the particles agglomerate in the electrolyte with the passage of time, thereby decreasing retention of the alkali carbonate melt. To further elucidate the growth mechanism of lithium aluminate particles, the effects of temperature, Pco2, and Li/K ratio in the melt on particle growth were determined. Equilibrium solubility measurements of lithium aluminate in a molten carbonate were also performed under various conditions. The results indicated that particle growth depends on the basicity of the electrolyte.

Lithiation of Alumina in Molten Li/K Carbonates

“…4 It is considered that in this phenomenon, small lithium aluminate particles dissolve into the molten carbonates as aluminate ions, which are then transported to the surface of large lithium aluminate particles where they deposit on the surface. Therefore, the results of experiment 3 indicate that the rate of corrosion of the sapphire plate surface increases under conditions where an increase in the solubility of lithium aluminate makes it easier for it to be transported as aluminate ions within molten carbonates.…”

“…The prepared polyaniline/Ti02 composite film was found to possess the ability to form images of high resolution with irradiation. [3][4][5][6] In order to demonstrate the utility of combining electrochromic materials with semiconductor particles for photoimage formation by irradiation without assistance of any electrical bias, we have studied an electrochromic material, prussian Nue (PB). PB is a mixed-valent iron cyanide complex formulated as Fe11[Fe'1(CN)6]3, which can be electrochemically deposited on several kinds of electrodes as a thin blue film.7-9 It is easily reduced to colorless prussian white (PW), and PW is oxidized to PB with high reversibility.…”

Carbonate Fuel Cell Matrix and Electrolyte Developments

“…Several studies in the literature have shown the particle coarsening of LiAlO 2 material in the liquid electrolyte (1)(2)(3)(4). Such coarsening appears to lower capillary force leading to drying of the matrix, resulting in accelerated increase in ohmic resistance and gas crossover.…”

“…However, the LiAlO 2 morphology may also play an important role to the coarsening rate, LiAlO 2 powder with a broad particle size distribution tends to show accelerated coarsening rate (8). Sotuchi et al (2) investigated the mechanism of LiAlO 2 solubility and crystal growth in carbonate electrolyte and proposed the following dissolution mechanism:…”

Conversion of gamma lithium aluminate to lithium aluminum carbonate hydroxide hydrate

“…For MCFC applications, it is generally agreed that gamma phase material with a surface area of about 10 m 2 /g is required. Changes in the physical properties of gamma-LiAlO 2 have been discussed by Sotouchi et al (1992) as a potential problem in MCFC life and performance. We have observed that lithium aluminum carbonate hydroxide hydrate, Li 2 Al 4 (CO 3 )(OH) 12 -3H 2 O (LACHH), forms when gamma LiAlO 2 is exposed to moisture and CO 2 at 25 °C.…”