Impressive capacity improvements can be obtained by wrapping insulating crystallites of Li3V2(PO4)3 within a conductive carbon web. The single crystal analysis (see Figure) and electrochemical characteristics of Li3V2(PO4)3 are reported. X‐ray diffraction analysis of the single phases formed on Li extraction shows that the framework is maintained with a little loss of crystallinity; on re‐insertion of Li, the Li3.0V2(PO4)3 framework is fully recrystallized.

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We have developed a novel nanocomposite material, [PANI]0.24MoO3, comprised of poly(aniline) chains interleaved with the layers of MoO3, using concomitant ion exchange−polymerization in the presence of an external oxidizing agent. The characterization of this material using SEM, FTIR spectroscopy, powder XRD, and thermal analysis shows that the poly(aniline) is present primarily in the emeraldine salt form. The high degree of ordering evident from the oriented film XRD patterns suggests that the PANI chains are at least partially aligned in the ac (basal) plane. The properties of the polymer nanocomposite for electrochemical lithium insertion were compared to those of the alkali molybdenum oxide using the materials as cathodes in conventional lithium cells. The polymer/oxide battery demonstrated substantially reduced cell polarization on galvanostatic cycling, compared to the alkali molybdenum oxide in the absence of PANI. The resultant enhanced ion and/or electron transport induced by incorporation of the polymer, in addition to the redox capacity of the intercalated PANI, provided a moderate increase in cell capacity and improved the reversibility of the Li insertion reaction.

Electrochemical (and chemical) lithium intercalation into a new vanadium phosphate, ε-VOPO 4 , is a two-phase process involving reduction of V V to V IV at an attractive potential (3.95V). X-ray diffraction shows that this material and that obtained from LiI reduction are structurally similar to high-temperature α-LiVOPO 4 . Increased stability and capacity are achieved with chemically lithiated ε-VOPO 4 when contact with the conductive additive is enhanced by mechanical grinding. Following the first charge cycle, reversible electrochemical lithium extraction/insertion at a cycling rate of C/10 affords a specific capacity of over 100 mAh/g (3.0-4.5 V window) that is stable for at least 100 cycles. This material demonstrates the best overall properties, thus far, of any polyanionic vanadium phosphate structure.Commercially available secondary lithium-ion batteries employ a transition metal oxide insertion host as the positive electrode. 1 Recently, transition metal phosphates have also been shown to be viable cathode materials, 2,3 especially where kinetic limitations to electronic conductivity can be surmounted. 4 Part of their appeal lies in the ability to tune the redox potential: in such materials as Li x M 2 (XO 4 ) 3 (M = transition metal; X = S, P, As), 2 and VOXO 4 (X = S, P, As) 3,5 for example, the induction effect of the anionic units has been shown to raise the potential of the redox couples compared to oxides by displacing electron density away from the metal center. The extent of the potential adjustment depends on X and the framework structure. Many of these compounds are synthesized via hightemperature solid-state routes. Recently, synthesis of a new VOPO 4 polymorph, designated ε-VOPO 4 , was reported by Lim et al. 6 They used hydrothermal methods to produce the VPO 4 ·H 2 O precursor that is thermally oxidized to yield ε-VOPO 4 . Herein we report on the first electrochemical studies of the ε-VOPO 4 phase and examine the use of chemical reduction and mechanical grinding on performance improvement. We show that this VOPO 4 phase, when chemically lithiated to produce Li x VOPO 4 , displays electrochemical properties superior to previously reported materials. We suggest this may be a consequence of relatively facile Li ion transport, and structural similarity of the lithiated and delithiated phases.The ε-VOPO 4 phase was prepared as previously reported, by treatment of the hydrothermally prepared precursor VPO 4 ·H 2 O at 500°C for 6 h in a flow of oxygen. 6 The general morphology and size of the particles remained unchanged from VPO 4 ·H 2 O after oxidation. The precise structure of this material has yet to be determined, although on the basis of Rietveld refinement studies, it is thought to be intermediate between VPO 4 ·H 2 O 7 and β-VOPO 4 . 8 Full profile fitting of our powder X-ray diffraction (XRD) data (Fig. 1a) gave an excellent fit to a monoclinic cell; P2 1 /n, with a = 7.268 Å, b = 6.882 Å, c = 7.265 Å, β = 115.36°similar to the parameters obtained by indexing reported by Lim et al. 6 Fu...

Surfactant-mediated transport of insoluble, hydrophobic polymers can be exploited to produce a novel interleaved metal oxide/polymer composite containing poly(p-phenylene). The synthetic route is illustrated in the scheme, whereby a surfactant bilayer between the MoO3 layers is displaced by the PPP/surfactant dispersion. Subsequent heat treatment results in concomitant combustion of the surfactant and collapse of the oxide layers, thus entrapping the PPP chains as a polymer monolayer in the interlamellar gap.