High lithium content of LixNi1-xO (0<x<0.5) for molten carbonate fuel cell cathode

The dissolution of lithiated nickel oxide and the deposition of dissolved nickel ions in molten carbonates electrolyte under cell operating conditions is considered to be one of the most important problems concerning molten carbonate fuel cell (MCFC) development. Lithiated nickel oxide (LixNi1-xO, 0<x<0.5) has a hexagonal phase over a wide range of lithium concentrations 1). LixNi1-xO which is in-situ oxidized and lithiated from the raw materials under a cathodic condition is stabilized between 0.02 and 0.04 of the x value. Therefore, LixNi1-xO with low lithium contents (0.02<x<0.04) is ordinarily used as the MCFC cathode material. LixNi1-xO with high lithium contents (0.1<x<0.5) as an improved cathode material for MCFC was studied for solubility restraint, It was found that LixNi1-xO with high lithium contents had a relatively lower rate of solubility than LixNi1-xO with low lithium contents and the changes in the lithium content of LixNi1-xO were very slow in molten carbonates. The amount of deposited nickel in the electrolyte using LixNi1-xO with high lithium contents as the cathode material was also measured after the single cell operation. The retarding effect on the nickel deposition by using LixNi1-xO with high lithium contents was confirmed, Typical results for the amount of deposited nickel in the Li/K(62/38 mol%) carbonate Electrolyte after cell operation was as follows : 3.8 mg/cm(2) using Li0.28Ni0.72O after 3637 h and 8.3 mg/cm(2) using Li0.02Ni0.98O after 4570 h.