Synthesis by a soft chemistry route and characterization of LixNi1-xO (0 < x < 0.5) compounds:: Behavior in molten carbonates

LixNi1-xO powders and LixNi1-xO/Au with 0 < x < 0.5 are synthesized by a soft chemistry route. Analysis of LixNi1-xO by XRD shows an evolution from NiO (0 < x < 0.3) to LiNiO2 (0.3 < x < 0.5) structures. The stability of LixNi1- O-x/Au (0 < x 0.5) compounds synthesized by soft chemistry is studied in molten (Li0.52Na0.48)(2)CO3 eutectic at 650 degrees C, under the cathode atmosphere used in molten carbonate fuel cells (air/CO2: 70/30). After a 48 h immersion, analysis by XRD of the lithiated nickel oxide shows that lithium ions diffuse from the oxide to the bulk of the melt. The major oxide detected at the surface of the sample has a composition very close to that of NiO formed in situ at the surface of a nickel foil. Hence, highly lithiated nickel oxides are not stable in the melt. LixNi1-xO is rapidly transformed confirming the very high stability of Ni(II) in the working conditions. (C) 2000 Kluwer Academic Publishers.