New inverse spinel cathode materials for rechargeable lithium batteries

The synthesis, characterization, and electrochemical properties of LiNiyCo1-yVO4(0 less than or equal to y less than or equal to) as the new cathode materials for rechargeable Lithium batteries were investigated. A series of LiNiyCo1-yVO4 (y = 0.1-0.9) compounds were synthesized by either a solid-state reaction of LiNiyCo1-yO2 and V2O5 at 800 degrees C for 12 h or a solution coprecipitation of LiOH . H2O, Ni(NO3)(2) . 6H(2)O, Co(NO3)(2) . 6H(2)O and NH4VO3, followed by heating the precipitate at 500 . C for 48 h. The products from both preparation methods were analyzed by scanning electron microcopy and inductively-coupled plasma-atomic emission spectroscopy. These compounds are inverse spinels based on the results from Rietveld analysis and the fact that the cubic lattice constant a is a Linear function of stoichiometry y in LiNiyCo1-yVO4. Either a 1 M LiClO4-EC + PC ( 1:1) or 1 M LlBF(4)-EC + PC + DMC (1:1:4) electrolyte can be used as the electrolyte for Li/LiNiyCo1-yVO4 cells up to y = 0.7. The charge and discharge capacity of a Li/1 M LiBF4-EC + PC + DMC ( 1:1:4) /LiNi0.5Co0.5VO4 cell were 43.8 and 34.8 mAh/g, respectively, when the cathode material was prepared by the low temperature coprecipitation method. (C) 1997 Elsevier Science S.A.