Phase formation and electrochemical properties of cryochemically processed Li1+xV3O8 materials

Li1+xV3O8 cathode materials for secondary Li batteries are prepared by freeze drying (FD) synthesis from aqueous solutions of NH4VO3 and various Li salts at different pH values. The polyanionic forms of vanadates in the FD products are significantly different from the ones existing in the starting solutions. The degree of VO3- Polymerization is influenced both by co-existing anion and by pH value of the starting solution. The appearance of NH4V3O8 among FD products promotes a faster formation of the crystallochemically similar LiV3O8 during the following solid state metathesis reaction. LiV3O8 powders obtained by the thermal decomposition of various FD precursors at 300-400 degrees C demonstrate rather different micromorphologies and drastically dissimilar electrochemical properties. The best electrochemical performance is exhibited by poorly crystalline but faceted fine particles obtained by the thermal decomposition of nitrate-containing precursor. (c) 2006 Elsevier B.V. All rights reserved.