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A conjugated aromatic compound comprising multiple fused redox centers, 5,7,12,14-tetraaza-6,13-pentacenequinone (TAPQ), is reported as an electrode of lithium-ion battery for the first time. It not only reaches a high reversible capacity but also obtains an excellent cycle ability. In addition, DFT calculations as well as FTIR, XPS and XRD analysis are performed to demonstrate the electrochemical reaction mechanism. This novel electrode can also be used in sodium and potassium batteries with a similar redox mechanism.

Tin-based composite oxide (TCO) thin films with a reversible capacity of 460 mAh/g and good stability were fabricated by pulsed laser reactive deposition in an oxygen ambient. X-ray diffraction and atomic force microscopy show that nanocrystalline SnO 2 is dispersed in an amorphous oxide matrix. The lithium ion insertion and extraction processes in a 1 M LiPF 6 nonaqueous electrolyte are examined. Cyclic voltammetry shows an irreversible reduction process in the first cycle. X-ray photospectroscopy spectra unambiguously revealed a conversion of Sn(IV) to metallic Sn. In situ spectroelectrochemical measurements demonstrate significant transmittance drops with the discharge of the Li/TCO cells. Our results show that the alloying of tin with lithium occurs reversibly following the irreversible reduction of tin oxide in the TCO film, which is consistent with the electrochemical mechanism proposed by Courtney and Dahn

Niobium oxide thin films have been successfully fabricated on the indium‐tin oxide coated glasses by pulsed laser deposition in an gas mixture. Films are characterized by X‐ray diffraction and Raman spectrometry. Electrochemical and electrochromic properties of films are examined by cyclic voltammogram and potential step coupled with an in situ charge‐coupled device spectrophotometer. The unique characteristics of absorption spectra of films are observed for the first time, and the optical absorption from the trapped electrons in the surface states plays an important role in the electrochromic phenomenon. © 1999 The Electrochemical Society. All rights reserved.

ZnO 1―x S x thin film has been successfully fabricated by pulsed laser deposition. The electrochemical properties are investigated by charge/discharge measurement and cyclic voltammograms. X-ray diffraction, x-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and selected area electron diffraction measurements are employed to explore their electrochemical reaction mechanism with lithium. Among all the ZnO 1―x S x compounds, ZnO 0.28 S 0.72 shows the best electrochemical performance with a large reversible specific capacity around 650 mAh/g and an excellent capacity retention. The electrochemical reaction mechanisms of the film in the charging and discharging processes involve the reversible decomposition/formation of ZnO 1―x S x and alloying/dealloying of ZnLi.

Nanostructured diamond like carbon (DLC) thin films were fabricated by radio frequency sputtering and their electrochemical behavior as air electrodes for Li-air batteries were investigated for the first time. These nanostructured DLC air cathodes presented high discharge plateaus around 2.7 V and large reversible capacities around 2318 mAh/g at the current rate of 220 mA/g. The reaction mechanism of DLC thin film electrodes of lithium air cells was revealed by ex situ Raman, Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) measurements. The formation of nanocrystalline Li(2)O(2) and amorphous Li(2)CO(3) was confirmed in the discharge products. Our results have demonstrated that DLC thin films with sp(3)-bonded carbon atoms due to their good cyclic performance and low polarization between discharging and charging profiles exhibit a promising candidate of air electrode materials for future lithium air batteries. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3623431] All rights reserved.

The electrochemical properties of nanocomposite Cr 2 O 3 ―InP thin film prepared by the pulsed laser deposition method have been investigated by cyclic voltammetry and charge/discharge measurements. The large reversible capacity of the nanocomposite Cr 2 O 3 ―InP thin film was 653 mAh/g. A couple of reduction and oxidation peaks at 1.45 and 1.14-2.6 V were observed from the cyclic voltammogram. The electrochemical reaction mechanisms of Cr 2 O 3 ―InP with lithium were examined by X-ray photoelectron spectroscopy, high resolution transmission electron microscopy, and selected area electron diffraction. An interesting anion exchange phenomenon was observed, wherein CrP instead of the original Cr 2 O 3 was formed as the charging product associated with the decomposition of Li 3 P rather than Li 2 O. The reversible alloying/dealloying of In with Li and the reversible formation and decomposition of CrP were involved in subsequent cycles.

The fabrication of Li 3 N-Si nanocomposite thin films is reported by pulsed laser deposition. The electrochemical properties were investigated by charge/discharge measurement and cyclic voltammograms. High-resolution transmission electron microscopy and selected area electron diffraction measurements were employed to explore the electrochemical reaction mechanism. An interesting result was achieved in that polycrystalline Si 3 N 4 was formed in the initial charge process. Afterward, a ternary compound Li 5 N 3 Si was revealed to be the lithiated product after discharge. The highly reversible processes in subsequent cycles were attributed to the reversible transition between Li 5 N 3 Si and Si 3 N 4 .

Amorphous iron phosphate (FePO 4 ) and nitrided iron phosphate (FePON) thin films have been fabricated by radio-frequency sputtering in ambience of oxygen and nitrogen, respectively. These thin film electrodes were applied in a variety of sandwich structures and all-solid-state thin film batteries of Li/LiPON/FePON (FePO 4 ) to examine the electrochemical kinetics by alternate-current impedance. Through the insertion of N, the ionic conductivity of FePON was greatly enhanced, but the electronic conductivity of FePO 4 was reduced. The charge-transfer resistance of FePON was dramatically decreased and the chemical diffusion coefficient of Li + ions into FePON was increased by the doping of N. A different electrochemical performance of FePON and FePO 4 was observed from cyclic voltammetry and charge/discharge measurements of all-solid-state batteries. The FePON, where 1.1 Li per FePON was inserted at the end of discharge, exhibited higher capacity than FePO 4 . The polarization of FePON was observed because of the asymmetrical redox peaks below 2.5 V.

An attempt was made to fabricate all-solid-state lithium-ion rechargeable batteries with amorphous iron phosphate (FePO 4 ) and iron phosphorous oxynitride (FePON) thin-film electrodes, which have been successfully fabricated by radio-frequency sputtering at oxygen and nitrogen ambient, respectively. The all-solid-state thin-film battery of Li/LiPON/FePON had a higher capacity of 63 μAh/cm 2 -μm than Li/LiPON/FePO 4 by discharge/charge measurement. For novel FePON thin-film electrode, the insertion of nitrogen into FePO 4 has been examined by X-ray photoelectron spectra and Raman spectroscopy. Our results demonstrated that FePO 4 and FePON thin film electrodes with the features of amorphous structure, good-matched interface with LiPON electrolyte, and low-temperature preparation conditions may make them attractive as cathodes for the all-solid-state thin-film lithium-ion batteries.

SnSe thin film prepared by reactive pulsed laser deposition (PLD) method was found to be a novel and promising anode material. Cyclic voltammetry (CV) and discharge and charge behaviors of Li/SnSe cells were examined, andthe reversible discharge capacities in the range from 400 to 681 mAh/g were achieved during the first 40 cycles. A reduction in oxidation peaks at 1.3 and 1.9 V from CV curves of Li/SnSe cell was first observed, indicating the reversible formation and decomposition of reaction of Li 2 Se. This feature is utterly different from those of SnO 2 or SnO and SnS 2 , in which Li 2 O and Li 2 S are inactive. The lithium electrochemical reaction of SnSe thin-film electrode has been investigated by scanning electron microscopy (SEM). X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Both classical alloying process and the selenidation-reduction of nanosized metal tin were revealed in lithium electrochemical reaction of SnSe. SnSe as the starting material for conversion to Li-Sn alloy can improve its electrochemical performance with high reversible capacity and good, stable cyclability, demonstrating a promising anode material for future rechargeable lithium batteries.

Copper selenide, Cu 2 Se, CuSe, and CuSe 2 , thin films have been successfully fabricated using pulsed laser ablation of mixed targets of Cu and Se. The substrate temperature was a key factor in preparing high-quality thin films of the copper selenides, with different crystalline structures and stoichiometries. Although these three kinds of compounds (Cu 2 Se, CuSe, and CuSe 2 ) all form thin films with the same anion and cation in their chemical formula, their electrochemical properties clearly differ from each other, evidently associated with their various compositions and structures. The galvanostatic cycling measurement indicates that a Cu 2 Se/Li cell has the best cycling performance when compared to the other two possible cells, CuSe 2 /Li and CuSe/Li. The conversion reaction mechanism between Cu 2+ (CuSe and CuSe 2 ) and Cu + (Cu 2 Se) are proposed for CuSe 2 /Li and CuSe/Li cell, while the Cu 2 Se/Li cell may undergo a "displacement" reaction mechanism according to X-ray diffraction, transmission electron microscopy, and selected area electron diffraction data. These complex and unique mechanisms make copper selenides interesting materials for rechargeable lithium batteries.

An attempt to extend the application of the electrochemical mechanism on nanosized transition metal in the range 1-5 nm to drive formation and decomposition of Li 2 O was made for other transition metal compounds. Using reactive pulsed laser deposition and dc discharge methods in a nitrogen ambient, a transition compound of Ni 3 N thin film has been fabricated successfully. The lithium electrochemical reaction of Ni 3 N thin-film electrode was first investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), the discharge and charge, cyclic voltammetry (CV), the in situ spectroelectrochemical measurements. An irreversible process in the lithium electrochemical reaction of Ni 3 N thin-film electrode was confirmed by spectroelectrochemical, CV, ex situ XRD, and XPS measurement. However, irreversible capacity loss between the first two cycles is only 5% of the first discharge. The observed diffraction peaks from metal nickel in the lithiated thin films showed good crystallinity with crystal size more than 5 nm confirmed by transmission electron microscopy (TEM) and selected area electron diffraction (SEADI). So the oxidation/reduction of nanosized metal may not be used for an explanation for the electrochemical behavior of Ni 3 N thin film. Another reaction mechanism involves rich transition metals dispersed into a lithium containing matrix, two kinds of roles of metallic nickel are revealed, one part of metallic nickel is nitrided and reduced in the lithium electrochemical reaction, another part of nickel seems to act as an active spectator to drive the formation and decomposition of Li 3 N.

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 ∼100 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.

The electrochemical and spectroelectrochemical properties of ZnO thin films prepared by reactive pulsed laser deposition in oxygen ambient have been investigated. The as-deposited and lithiated ZnO thin films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy techniques. The discharge and charge measurement indicates that the reversible capacities of the as-deposited ZnO thin-film electrodes are more than one Li per Zn atom with an initial capacity of less than 2.75 Li per Zn atom, and more than 0.75 Li per Zn atom could not be explained by the alloying process of ZnO reaction with Li. The evolution of the in situ absorbance spectra exhibits a marked boundary of lithiating 2Li per Zn atom and provides a hint about two different lithiation reactions occurring during charging of the ZnO/Li cell. A new reaction mechanism of lithium with ZnO involving both the classical alloying process and the oxidation/reduction of nanosized metal is proposed.

Electrochemical and isothermal transient ionic current (ITIC) methods have been successfully employed for the first time to investigate the lithium insertion and transport behavior in a Ta 2 O 5 film prepared by pulsed laser deposition. Cyclic voltammogram and potential step measurements were used to examine the insertion processes of Li ions into Ta 2 O 5 film electrodes. The potential step measurements showed that the Li ion diffusion constants in β-Ta 2 O 5 film electrodes were dependent on the stepping potential and found to be in the range of 5.2 × 10 -14 to 3.8 × 10 -12 cm 2 /s. Based on the ITIC measurements, the Li-ion diffusion constants in β-Ta 2 O 5 film electrodes were estimated to be in the range of 2.6∼5.2 10 -15 cm 2 /s. In addition, the trap states in β-Ta 2 O 5 film should be responsible for the typical ITIC curves.