Electrochemical performance of VOMoO<inf>4</inf> as negative electrode material for Li ion batteries

Polycrystalline samples of VOMoO4 are prepared by a solid-state reaction method and their electrochemical properties are examined in the voltage window 0.005-3 V versus lithium. The reaction mechanism of a VOMoO4 electrode for Li insertion/extraction is followed by ex situ X-ray diffraction analysis. During initial discharge, a large capacity (1280 mAh g-1) is observed and corresponds to the reaction of ∼10.3 Li. The ex situ XRD patterns indicate the formation of the crystalline phase Li4MoO5 during the initial stages of discharge, which transforms irreversibly to amorphous phases on further discharge to 0.005 V. On cycling, the reversible capacity is due to the extraction/insertion of lithium from the amorphous phases. A discharge capacity of 320 mAh g-1 is obtained after 80 cycles when cycling is performed at a current density of 120 mA g-1. © 2007 Elsevier B.V. All rights reserved.