Electrochemical Lithium Intercalation into Vanadium Pentoxide Xerogel Film

Abstract

The lithium-ion transport in vanadium pentoxide xerogel film electrodes has been investigated by using cyclic voltammetry and electrochemical impedance spectroscopy. The oxide xerogel film electrodes were prepared by spin-coating a viscous gel on an indium tin oxide (ITO) substrate. The spin-coated xerogel films were dried under vacuum at 130 and 270 degrees C, respectively, The lithium intercalation into the xerogel film electrode dried at 270 degrees C is limited by the interfacial reaction at the electrolyte/electrode interface rather than the lithium-ion transport in the oxide electrode. On the other hand, lithium intercalation into the film electrode dried at 130 degrees C is largely limited by the lithium transport in the oxide film, and the chemical diffusivity of the lithium ion in the oxide film was determined to decrease from 10(-10) to 10(-12) cm(2) s(-1) as the electrode potential of the oxide film fell from 3.0 to 2.2 VLi/Li+. The transition of the diffusion-controlled intercalation to the interfacial reaction-controlled intercalation into the oxide xerogel film with decreasing drying temperature was explained in terms of the modification of the oxide lattice to a more open-structured lattice by structural modification of the oxide film by water molecules incorporated into the film. (C) 1997 Elsevier Science S.A.