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

The synthesis process and microstructural evolution of LiNiVO4, a potential cathode material used in lithium ion secondary batteries, prepared by soli d-state reaction have been investigated in this study. The formation proces ses of LiNiVO4 are characterized to be an initial dissociation of LiVO3. 0. 5H(2)O to form LiVO3, followed by a subsequent reaction between LiVO3 and N iO to produce LiNiVO4 from above 600 degrees C. After calcination at 700 de grees C for 6 h, monophasic LiNiVO4 has been successfully prepared. Further raising the temperature to 800 degrees C reduces the required heating time to 4 h. In comparison with the results in previous reports, the heating ti me for synthesizing LiNiVO4 is significantly reduced in the study. The micr ostructure of LiNiVO4 is found to markedly depend on the heating processes. Increasing heating temperature as well as soaking time results in non-unif orm microstructure of the specimens. In the regions having nonstoichiometri c composition, the microstructure of the specimens becomes well densified a nd experiences exaggerated grain-growth. The above phenomena imply that liq uid-phase sintering has occurred in the above regions. (C) 1999 Elsevier Sc ience Limited and Techna S.r.l. All rights reserved.