THE DISSOLUTION PROPERTIES OF LICOO2 IN MOLTEN 62-38 MOL-PERCENT LI-K CARBONATE

The lifetime of a Molten Carbonate Fuel Cell (MCFC) is reduced by the slow dissolution of the state-of-the-art lithiated nickel oxide cathode material. LiCoO2 is considered to be an alternative cathode material by its good performance in MCFC tests. However, its dissolution rate was not known. In this letter the dissolution properties of LiCoO2 in 62:38 (Li:K)2CO3 at 923 K are reported. The concentration of the dissolved Co2+ ions in the molten carbonate was determined electrochemically and by ICP-AES. The solubility depends on [pCO2]1/2 and [pO2]1/4. Under cathode-gas conditions the solubilities ranged from 2 to 13 wt ppm, whereas the corresponding values for lithiated nickel oxide ranged from 7 to 20 wt ppm. The dissolution rate was determined from post-test analyses of small scale MCFC tests to be less than 0.5-mu-g Co/cm2 h, which is about an order of magnitude lower than that for nickel oxide.