Nanocrystalline ZnFe 2 O 4 and Ag x ZnFe 2 O 4 (x ϭ 0.16, 0.37, 0.50) thin films have been prepared by reactive pulsed laser deposition, and used as anode materials for Li-ion batteries for the first time. X-ray diffraction ͑XRD͒ and scanning electron microscopy measurements showed that the prepared films were composed of a nanocrystalline structure with the average particle size less than 100 nm. The initial reversible capacity of ZnFe 2 O 4 and Ag 0.37 ZnFe 2 O 4 film electrodes reached 556 and 700 mAh/g, respectively, at a current density of 10 A cm Ϫ2 between 0.01 and 3.0 V. The Ag 0.37 ZnFe 2 O 4 film electrode exhibited better cyclability than ZnFe 2 O 4 film electrode, and retained 91% of the reversible capacity up to 100 cycles. According to our results on cyclic voltammetry of Li/ZnFe 2 O 4 cell coupled with ex situ photoelectron spectroscopy and XRD measurements of as-deposited and lithiated film electrodes, we suggest that the mechanism of ZnFe 2 O 4 film reacted with lithium involves reduction of Zn 2ϩ and Fe 3ϩ to metallic Zn and Fe 2ϩ , accompanying the formation of Li-Zn alloy. The dramatically improved electrochemical performance of Ag 0.37 ZnFe 2 O 4 film electrode might be related to the change of the reaction process after silver doping.

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The binding constants of non-covalent cyclodextrin-alkali cation complexes have been systematically studied by an improved mass spectrometric titration and competitive ESI-MS. Also, the structural features of the complexes were discussed. Our results are valuable for better understanding of mechanisms driving inclusion chemistry under well-defined conditions.

Amorphous Ta 2 O 5 film has been fabricated by reactive pulsed laser deposition and used for the first time as an anode material for the lithium ion rechargeable batteries. This thin film of anode material exhibits a reversible capacity of 400 mAh/g and a low initial irreversible capacity of ϳ100 mAh/g. Spectroelectrochemical measurements coupled with X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, and electron diffraction have been employed to characterize the as-deposited tantalum oxide film electrode and its lithiated electrode. According to results of the XPS and measured high reversible capacity corresponding to more than 6 Li per Ta 2 O 5 , the reversible reaction of an amorphous tantalum oxide film with lithium different from the lithium ion insertion/extraction process for Li ion anodes is proposed.Many efforts have been devoted to the search for new anode materials for lithium batteries instead of carbonaceous and graphite electrode, because these electrodes during charging of the Li-ion battery may produce metallic lithium and then give rise to safety problem. 1 Amorphous tin-based composite oxide ͑TCO͒ as an anode material showed some promise due to good stability and a high reversible capacity of 600 mAh/g. However, a large initial irreversible capacity of ϳ380 mAh/g related to the irreversible reaction of lithium with tin oxide are inherent drawback. 2-4 Transition metal oxides such as iron-based oxides, 5 Nb 2 O 5 , 6 and CoO, NiO, CuO, FeO 7 have also been proposed as an anode electrode and have received considerable attention. In the meantime, the lithiation mechanism of these electrodes has been studied in order to understand the electrochemical properties. Recently, Tarascon et al. reported a new reaction mechanism for the transition metal oxides ͑MO, M ϭ Co, Ni, Fe, Cu͒ reacted with lithium involving the reversible formation and decomposition of Li 2 O, accompanying the reduction and oxidation of metal nanoparticles. 7 Thin-film electrodes with promising electrochemical performance have been widely studied for developing all-solid-state thinfilm lithium-ion batteries. 8 Pulsed laser deposition ͑PLD͒ has been employed to fabricate LiMn 2 O 4 , LiCoO 2 , Nb 2 O 5 , V 2 O 5 , and TCO thin-film electrodes with high-quality electrochemical properties. 3,[9][10][11] By using this technique, we have fabricated Ta 2 O 5 thin-film electrodes and investigated their electrochromics and lithium-ion transport in thin-film electrodes. 12,13 However, there is no available information on the characterization of tantalum oxides as electrodes for the application in all-solid-state thin-film lithiumion batteries. In this paper, considering inherent features such as the safety, low cost, and low toxicity of tantalum oxide, an attempt is made to characterize the Ta 2 O 5 film as an anode material fabricated by PLD, and the specific capacity, rate capability, and long-term cycleability of this film anode are presen...

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