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Free-standing, flexible, and binderless binary ZnO-reduced graphene oxide (rGO), SnO2-rGO, and ternary ZnO-SnO2-rGO Li-ion anodes were produced by vacuum filtrating the mixture of metal oxides synthesized by sol-gel method and graphene oxide produced by Hummers method. These paper anodes were designed by being decorated with metal oxides between rGO layers. To compare nanocomposite anode structures, field emission gun-scanning electron microscopy, energy dispersive X-ray spectrometer, X-ray diffraction, and electrochemical analyses were applied. The results suggested that ternary ZnO-SnO2-rGO paper anode exhibited larger discharge capacity and capacity retention than the binary anodes even after 100 cycles. This finding is attributed to buffering effect of rGO on volume expansion of the anode structure designed by sandwich-type production and the synergic effect of ZnO-SnO2 oxides.

Freestanding tin oxide-boron oxide/reduced graphene oxide (SnO$_{2}$-B$_{2}$O$_{3}$/rGO) nanocomposite anode was produced for Li-ion cells. This binder-free flexible paper anode structure was fabricated by combining SnO$_{2}$-B$_{2}$O$_{3}$ composite and graphene oxide which were synthesized through the sol-gel method and Hummers' method, respectively. Field emission gun scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectrometer, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray diffraction were utilized to characterize anode materials. The Williamson-Hall (W-H) analysis was applied using XRD data to determine crystal size and strain of the lattice. Electrochemical tests, cyclic voltammetry, and electrochemical impedance spectroscopy measurements were performed to determine electrochemical properties of the anodes. The results indicated that the anode formed with SnO$_{2}$-B$_{2}$O$_{3\, }$particles anchored on the rGO layers provided higher discharge capacity (838 mAh g$^{-1})$ than that of SnO$_{2}$/rGO (395 mAh g$^{-1})$ after 100 cycles. The electron-deficient nature of boron supplied an effective increase in electrochemical energy storage performance.

Free standing zinc oxide (ZnO) and multiwalled carbon nanotube (MWCNT) nanocomposite materials are prepared by a sol gel technique giving a new high capacity anode material for lithium ion batteries. Freestanding ZnO/MWCNT nanocomposite anodes with two different chelating agent additives, triethanolamine (TEA) and glycerin (GLY), yield different electrochemical performances. Field emission gun scanning electron microscopy (FEG-SEM), energy dispersive X-ray spectrometer (EDS), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) analyses reveal the produced anode electrodes exhibit a unique structure of ZnO coating on the MWCNT surfaces. Li-ion cell assembly using a ZnO/MWCNT/GLY free-standing anode and Li metal cathode possesses the best discharge capacity, remaining as high as 460 mAh g(-1) after 100 cycles. This core-shell structured anode can offer increased energy storage and performance over conventional anodes in Li-ion batteries. (C) 2015 Elsevier B.V. All rights reserved.

Different morphologies of thermoelectric Bi(1-x)Sb(x) and Bi(2-x)Sb(x)Te(3) thin films, including rods, dendrites, thin sheets, and spherical particles, were selectively obtained by an electrodeposition method at room temperature (25 degrees C). Cyclic voltammetry was used for determination of the deposition potentials of thin films. The influences of the deposition potential and the electrolyte composition on the films were studied. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) were employed to characterize the thin films. It was found that the different shaped Bi-rich Bi(1-x)Sb(x) films can be obtained by tuning the electrolyte composition. However, the Bi(2-x)Sb(x)Te(3) films can be fabricated by changing the deposition potential. In underpotentials (UPD), the reduction reactions of Bi(3+), Te(4+), and Sb(3+) take place to form (Bi(0.5)Sb(0.5))(2)Te(3). When the potential shifts into overpotentials (OPD), Bi(0.5)Sb(1.5)Te(3) is formed on the electrode surface. The EDS data indicates that the composition of the films is consistent with XRD results. The SEM investigations show that the growth mechanism of deposited Bi(1-x)Sb(x) and Bi(2-x)Sb(x)Te(3) films depends on the electrolyte composition and the deposition potential, respectively.

Bi2Te3-7Sey thin films were grown on Au(1 1 1) substrates using an electrochemical co-deposition method at 25 degrees C. The appropriate co-deposition potentials based on the underpotential deposition (upd) potentials of Bi, Te and Se have been determined by the cyclic voltammetric studies. The films were grown from an electrolyte of 2.5 mM Bi(NO3)(3), 2 mM TeO2, and 0.3 mM SeO2 in 0.1 M HNO3 at a potential of -0.02 V vs. Ag/AgCl (3 M NaCl). X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were employed to characterize the thin films. XRD and EDS results revealed that the films are single phase with approximate composition of Bi2Te2.7Se0.3. SEM studies showed that the films are homogeneous and have micronsized granular crystallites. (C) 2008 Elsevier Ltd. All rights reserved.

Electrolytes which have different LiBF4 salt concentrations (0.8 m, 1.0 m, 1.2 m and 1.4 m) in the ratio of 2:1 (w/w) Ethylene Carbonate (EC): Dimethyl Carbonate (DMC) solvents were prepared. Obtained electrolytes were used to assemble half-cells containing metallic Li anode and nanostructured LiMn2O4 cathode material. In order to investigate the effect of LiBF4 salt concentration on the stability of LiMn2O4 cathode material after electrochemical tests with 100 cycles, the cells were disassembled and the cathode materials were taken out to examine the effect of electrolyte solutions on the stability of nanostructured LiMn2O4 cathode materials via Raman, XRD and FEG-SEM methods. The optimum LiBF4 salt concentration was found for LiBF4-EC-DMC based electrolyte solutions and results showed that higher salt concentration contributes to the stability of the bare nanostructured LiMn2O4 cathode material even after 100 cycles charge-discharge test. In addition, the electrode degradation arising from the lower LiBF4 salt concentration is compatible with the electrochemical capacity fading for the cathode materials compared with our previous work. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

In this work, sol-gel method was used in order to synthesize ZnO nanoparticles. Zn(CH3COO)(2)center dot 2H(2)O was used to obtain ZnO precursor solution. To investigate the effect of organic gelating agents on grain size, various organic gelating agents such as triethanolamine (TEA), glycerin (GLY), ethylene glycol (EG), citric acid (CA) and tartaric acid (TA) were used. X-ray diffraction analysis was used for phase identification and grain size calculation. ZnO powders were characterized by using Fourier-transform infrared spectroscopy, scanning electron microscopy and atomic force microscopy.

Electrolytes were prepared with different LiBF4 salt concentrations in the ratio of 2:1 (w/w) Ethylene Carbonate (EC): Dimethyl Carbonate (DMC) solvents. Different LiBF4 concentrations were used in the electrolytes to assemble half-cells containing metallic Li anode and nanostructured LiMn2O4 cathode material. To investigate the effect of LiBF4 salt concentration on the electrochemical performance of nanostructured LiMn2O4 cathode material, electrochemical tests were performed at room temperature. For LiBF4-EC-DMC based electrolytes, the optimum LiBF4 salt concentration was found and results showed that higher salt concentration provides higher electrochemical capacity for the bare nanostructured LiMn2O4 cathode materials but did not result in preventing capacity fade due to electrode degradation. (C) 2015 Elsevier Ltd. All rights reserved.