Synthesis and electrochemical properties of vanadium oxide aerogels prepared by a freeze-drying process

Vanadium oxide aerogels have received considerable interest as a reversible electrode material for lithium secondary batteries. The aerogel morphology is a critical factor in obtaining the electrochemical properties of these materials. The present paper reports on the synthesis of V2O5 by freeze-drying, an alternative approach for producing a material with an aerogel-like morphology. In this synthesis, the sublimation of cyclohexane circumvents the capillary pressures which cause pore collapse during the normal solvent removal process. The resulting materials are very porous with specific surface areas as high as 250 m(2)/g. The electrochemical properties of the freeze-dried material are strongly influenced by both the specific surface area of the solid phase and crystallite size. The controlled heat-treatment of the aerogel produces a omega-LixV2O5-type phase with improved capacity and reversibility. (C) 2004 The Electrochemical Society.