Soft-combustion synthesis of a new cathode-active material, LiVWO6, for lithium-ion batteries

Brannerite-LiVWO6, has been synthesized by employing a wet-chemical soft-co mbustion (low temperature) technique and its battery-active character as ca ndidate cathode material in lithium-containing batteries is reported in the light of electrochemical means. Structural and thermal properties have als o been studied by means of classical techniques such as XRD and thermal ana lysis. The structural features are found to be similar to its analogous cou nterpart, brannerite-LiVMoO6 previously reported. Quasi-layered type LiVWO6 crystallizes in brannerite structure of AB(2)O(6) type, having a general f ormula LiM2'O-6 (M ' = transition metal) with lattice parameters a = 9.347 Angstrom, b = 3.670 Angstrom, c = 6.593 Angstrom and beta = 111 degrees 50 '. The thermochemical reactions that occur during the soft-combustion of th e precursor mass facilitate the formation of the above compound at 434 degr eesC as deduced from TG-DTA scan. The product (LiVWO6) thus prepared (calci ned at 700 degreesC) exhibits the submicrometer grains (<1 mum) whose speci fic surface area is found to be 4.97 m(2)/g as deduced from BET analysis. T he redox behavior of the above compound has been examined for LiVWO6/Li+/Li under the wet electrolyte (1 M LiPF6: EC + DMC) environment in the voltage regime 4.0 and 1.5 V using constant current technique at a current density of 0.8 mA/cm(2). It has been found that the test cell containing LiVWO6/Li couple demonstrates excellent charge-discharge behavior in the voltage reg ime 3.0-1.5 V and the specific capacity of similar to 240 mAh/g has been de duced from the first charge-discharge cycle in the voltage regime similar t o4.0-1.5 V. (C) 2001 Elsevier Science B.V. All rights reserved.