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

Author： Belhomme C. Cassir M. Devynck J. Gregoire G.

Publisher： Springer Publishing Company

ISSN： 0022-2461

Source： Journal of Materials Science, Vol.35, Iss.11, 2000-06, pp. : 2683-2688

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Abstract

Li_xNi_1 − xO powders and Li_xNi_1 − xO/Au with 0 < x < 0.5 are synthesized by a soft chemistry route. Analysis of Li_xNi_1 − xO by XRD shows an evolution from NiO (0 < x < 0.3) to LiNiO_2 (0.3 < x < 0.5) structures. The stability of Li_xNi_1 − xO/Au (0 < x 0.5) compounds synthesized by soft chemistry is studied in molten (Li_0.52Na_0.48)_2CO_3 eutectic at 650°C, under the cathode atmosphere used in molten carbonate fuel cells (air/CO_2: 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. Li_xNi_1 − xO is rapidly transformed confirming the very high stability of Ni(II) in the working conditions.