Li is intercalated into V205 (XRG) films up to a stoichiometry of 3.3 moles Li/mole V205 (XRG) (3.8 < V vs. Li ~< 1.9). The spin-coated films are highly reversible hosts for Li and do not support cointercalation of solvent molecules. The specific energy (1137 Wh/kg), and specific capacity (1682 C/g) are higher than any reported previously for V205 xerogel materials or for other vanadium oxides. It is noted that VzO~ (XRG) resembles amorphous V205 modified to some extent by the ordered arrangement of ribbons and fibrils in the dried films. * Electrochemical Society Student Member.

Amorphous vanadium pentoxide false(V2O5false) has been investigated as an intercalation material for Li‐ion batteries due to its high specific energy and high capacity for Li intercalation. However, the rate of insertion is typically limited by lithium diffusion in the host and by its modest conductivity. The present work demonstrates that high intercalation rates are possible if the host microstructure is modified to decrease the characteristic lithium diffusion distance and the characteristic conduction distance. Thin films of V2O5 were grown by preferential gelation on sintered nickel fibers via a sol‐gel route. Electrochemical impedance measurements of the composite electrodes indicated that diffusion limitations in the host were successfully avoided. Constant current cycling and cyclic voltammetry were also used to characterize the composites. Specific powers, based on mass of active material, of almost 6 MW/kg were observed. © 1999 The Electrochemical Society. All rights reserved.

Photoelectrochemical microscopy (PEM) was used to locate pitting precursor sites on polycrystalline titanium immersed in sulfuric acid and in ferrocyanide solutions. PEM imaging was done with both a conventional method and a new shear-force feedback method. The resolution of the PEM images obtained are highly dependent upon the size and preparation procedure of the optical fiber used for the test. 1 m diam etched tips yield higher lateral resolution images compared to commercially available "pulled" tips. PEM with simultaneous independent topography (using the tuning fork method) resolved submicron features at precursor sites at inclusions and grain boundaries. Both PEM and topographic images were obtained in situ with high lateral resolution by using specially fabricated tips with 100 nm aperture.

1428iconductor surface. However, when there is no interaction between the semiconductor and the sensitizer, one can expect the triplet excited state to participate in a diffusionantrolled charge injection process. The charge injection from the triplet excited thionine into ZnO colloids ( k = 6.7 X lo4 s-I) and a quantum yield for the net charge transfer (4 = 0.1) were found to be maximum at monolayer werage of thionine. Reverse electron transfer between J. Phys. Chem. 1992, 96, 1428-1430 the injected charge and the dye cation radical is still a limiting factor in controlling the efficiency of net charge transfer.Scanning tunneling spectroscopy (STS) has been used to determine the band structure of polypyrrole. The polypyrrole films were electropolymerid onto a highly oriented pyrolytic graphite surface using a rotating disk electrode. Differential conductance spectra measurements allowed us to follow the evolution of the band gap as a function of doping level. Before and after the STS measurements, the film structure was imaged by scanning tunneling microscopy. The STS results agree with data obtained by inverse photoemission spectroscopy. IntroductionScanning tunneling spectroscopy (STS) is a new technique

High Surface Area V2O5 Aerogel Intercalation Electrodes.-Amorphous V2O5 aerogels are prepared by supercritical drying of V2O5/ acetone gels with liquid CO2 (1200 pci, 32 • C). The aerogel consists of a highly interconnected solid network and has a surface area of ≤ 450 m2/g and a specific pore volume of 2.3 cm3/g. A study of the lithiation of this material shows that up to 4 Li+ per V2O5 unit can be intercalated both chemically by reaction with nBuLi and electrochemically from nonaqueous LiClO4 containing electrolytes. The V2O5 aerogel has the highest specific energy (¿ 1600 Wh/kg) ever reported for the different forms of V2O5 (e.g., crystallinesplat-cooled, sputtered amorphous, xerogel). -(LE, D. B.; PASSERINI, S.; GUO, J.; RESSLER, J.; OWENS, B. B.; SMYRL, W. H.; J.