Fabrication and microstructure of lithium nickel vanadium oxide prepared by solid-state reaction

Abstract

The synthesis process and microstructural evolution of LiNiVO 4, a potential cathode material used in lithium ion secondary batteries, prepared by solid-state reaction have been investigated in this study. The formation processes of LiNiVO 4 are characterized to be an initial dissociation of LiVO 3 .0.5H 2O to form LiVO 3, followed by a subsequent reaction between LiVO 3 and NiO to produce LiNiVO 4 from above 600°C. After calcination at 700°C for 6 h, monophasic LiNiVO 4 has been successfully prepared. Further raising the temperature to 800°C reduces the required heating time to 4 h. In comparison with the results in previous reports, the heating time for synthesizing LiNiVO 4 is significantly reduced in the study. The microstructure of LiNiVO 4 is found to markedly depend on the heating processes. Increasing heating temperature as well as soaking time results in non-uniform microstructure of the specimens. In the regions having nonstoichiometric composition, the microstructure of the specimens becomes well densified and experiences exaggerated grain-growth. The above phenomena imply that liquid-phase sintering has occurred in the above regions.