A Solubility Study of Prelithiated NiO and Prelithiated Cobaltite as Cathode Materials for MCFC in 62 Li-38 K Eutectic Carbonate Melts

The solubility of prelithiated NiO and prelithiated cobaltite as cathode materials for MCFC in 62 Li-38 K eutectic carbonate melts was studied with immersion test method. It was found that the solubility of either prelithiated NiO or prelithiated cobaltite was affected by its lithium (Li) content. The higher Li content was, the lower solubility could be in the range of 0∼0.25 mole fraction of Li. With the prelithiated NiO at Li content of 0.2 mole fraction, Ni solubility was reduced to 3∼4 × 10−6 mole fraction, which was only one-third of that of the normal NiO cathode in 30% CO2-70% air at 1 atm. It was obtained that the solubility of prelithiated cobaltite and even LiCoO2 were higher than the prelithiated NiO in the low O2 concentration gas. This suggested that even LiCoO2 was not stable in the O2 depleting condition, and more soluble than NiO.