TiO2/MoO2 nanocomposite as anode materials for high power Li-ion batteries with exceptional capacity

Nanoparticles of molybdenum(IV) oxide (MoO 2 ) and a TiO 2 /MoO 2 nanocomposite were synthesised via a continuous hydrothermal synthesis process. Both powders were analysed using XRD, XPS, TEM, and BET and evaluated as active materials in anodes for Li-ion half-cells. Cyclic voltammetry and galvanostatic charge/discharge measurements were carried out in the potential window of 0.1 to 3.0 V vs. Li/Li+. Specific capacities of ca. 350 mAh g -1 were obtained for both materials at low specific currents (0.1 A g -1 ); TiO 2 /MoO 2 composite electrodes showed superior rate behaviour & stability under cycling (compared to MoO 2 ), with stable specific capacities of ca. 265 mAh g -1 at a specific current of 0.5 A g -1 and ca. 150 mAh g -1 after 350 cycles at a specific current of 2.5 A g -1 . The improved performance of the composite material, compared to MoO 2 , was attributed to a smaller particle size, improved stability to volume changes (during cycling), and lower charge transfer resistance during cycling. Li-ion hybrid electrochemical capacitors using TiO 2 /MoO 2 composite anodes and activated carbon (AC) cathodes were evaluated and showed excellent performance with an energy density of 44 Wh kg -1 at a power density of 600 W kg -1

Corrosion Prevention of Aluminum Nanoparticles by a Polyurethane Coating

In order to prevent corrosion, aluminum nanoparticles were coated with a polyurethane polymer. The coverage of the polyurethane polymer was controlled from 0 to 100%, which changed the corrosion rate of the nanoparticles quantitatively. The surface of the polymer coating was investigated by Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM), and the corrosion resistance of the nanoparticles was estimated by a wet/dry corrosion test on a Pt plate with a NaCl solution. From a TEM with EDAX analysis, the 10 mass% polymer coated Al particles in the synthesis were almost 100% covered on the surface by a polymer film of 10 nm thick. On the other hand, the 3 mass% polymer coated Al was almost 40% covered by a film. In the AFM, the potential around the Al particles had a relatively low value with the polymer coating, which indicated that the conductivity of the Al was isolated from the Pt plate by the polymer. Both the corrosion and H2 evolution reaction rates were quantitatively reduced by the mass% of polymer coating. In the case of the 10 mass% coated sample, there was no corrosion of Al nanoparticles. This fact suggested that the electrochemical reaction was suppressed by the polymer coating. Moreover, the reaction rate of Al nanoparticles was suppressed in proportion to the coverage percentage of the coating. Thus, to conclude, it was found that the corrosion rate of Al nanoparticles could be quantitatively suppressed by the coverage percentage of the polymer coating

Monitoring of Environmental Factors and Corrosion Analysis of Reinforcing Steel in Mortar

To understand environmental factors in mortar, the Cl ion concentration and pH were monitored by inserting microelectrodes into artificial pores in the mortar. At the same time, the corrosion behavior of the reinforcing steel was investigated by EIS. In the EIS measurements of the reinforcing steel, Warburg impedance by diffusion was confirmed in the initial period, but it could no longer be observed after 35 days. In comparison with a 10 mm cover thickness, a 20 mm cover thickness showed a higher impedance behavior. The Cl ion concentration in the mortar was obtained using Ag/AgCl microelectrodes, showing that this behavior is generally controlled by diffusion. When the diffusion equation was used in this work, the diffusion coefficient (D c ) showed a high value of D c ¼ 2 Â 10 À4 mm 2 /s. Similarly, the pH in the mortar was obtained using W/WO x microelectrodes. With a 20 mm cover thickness, pH was limited to approximately pH 11, but with a 10 mm cover thickness, pH continued to decrease to around pH 9.5. The latter phenomenon was considered to be the result of neutralization by penetration of the immersion solution from the surface. Based on the results of monitoring with the microelectrodes, solutions simulating those in the pores in mortar were prepared and used in EIS measurements. The charge transfer resistance R ct in the simulated solutions showed good correspondence with the impedance (Z 2mHz ) in the low frequency region (2 mHz) in the actual mortar. This is attributed to the fact that the corrosion of reinforcing steel was controlled by the solution conditions (mainly Cl concentration and pH) in the pores in mortar. If these solution conditions (Cl concentration, pH) exceed threshold values, it was found that the passivation film is destroyed, resulting in high corrosion

Electrochemical characterization of TiO_2/WO_x nanotubes for photocatalytic application

TiO_2/WO_x nanotubes have unique photo-energy retention properties that have gathered scientific interest. Herein, we report the synthesis, morphological characterization, and the electrochemical characterization of TiO_2/WO_x nanotubes compared with pure TiO_2 nanotubes, prepared by anodization technique. Significant structural differences were not observed in TiO_2/WO_x nanotubes as observed by using scanning electron microscopy and transmission electron microscopy. The charge transfer resistance of TiO_2/WO_x before and after photo irradiation determined by using electrochemical impedance spectroscopy proves the inherent energy retention property which was not observed in pure TiO_2 nanotubes

Lithium ion conductive behavior of TiO_2 nanotube/ionic liquid matrices

A series of TiO_2 nanotube (TNT)/ionic liquid matrices were prepared, and their lithium ion conductive properties were studied. SEM images implied that ionic liquid was dispersed on the whole surface of TNT. Addition of TNT to ionic liquid (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (BMImTFSA)) resulted in significant increase of ionic conductivity. Furthermore, lithium transference number was also largely enhanced due to the interaction of anion with TNT. Vogel-Fulcher-Tammann parameter showed higher carrier ion number for TNT/BMImTFSA in comparison with BMImTFSA

Few-Layered MoS2/Acetylene Black Composite as an Efficient Anode Material for Lithium-Ion Batteries

Abstract Novel MoS2/acetylene black (AB) composite was developed using a single-step hydrothermal method. A systematic characterization revealed a few-layered, ultrathin MoS2 grown on the surface of AB. The inclusion of AB was found to increase the capacity of the composite and achieve discharging capacity of 1813 mAhg−1

Alternating Poly(borosiloxane) for Solid State Ultrasensitivity Toward Fluoride Ions in Aqueous Media

Facile synthesis of alternating copolymer poly­(borosiloxane) via dehydrocoupling was successfully carried out in the presence of transition metal catalyst at room temperature. The polymer was characterized by NMR and IR spectroscopy. The presence of a single peak in ¹¹B NMR and ²⁹Si NMR supported the alternating sequence of the polymer which was further complimented by the study of specifically designed model reactions. Fluoride ion sensitivity was analyzed by electrochemical methods.. The anion selective electrode prepared using synthesized polymer was found to be extremely sensitive toward fluoride ions (10^–10 M in aqueous media) by potentiometric measurements using 0.1 M disodium hydrogen phosphate as supporting electrolyte, Ag/AgCl as reference electrode, and Pt wire as counter electrode

BIAN Based Electroactive Polymer with Defined Active Centers as Metal-Free Electrocatalysts for Oxygen Reduction Reaction (ORR) in Aqueous and Nonaqueous Media

We report design, synthesis, and performance evaluation of functional polymer material with defined active sites for oxygen reduction reaction (ORR) catalytic activity in aqueous as well as nonaqueous media. The BIAN-paraphenylene (BP) copolymer having an imine backbone was synthesized via solution based polycondensation. The as synthesized polymer itself showed ORR activity comparable to that of other doped carbon materials. The composites of the polymer with graphene oxide (GO) sheets (GO/BP) were also synthesized under moderate temperature conditions (400 °C) with the polymer remaining intact. The composites showed further enhanced electrochemical activity owing to the synergistic effect of GO and active site defined polymer material. We also tried to evaluate the nature and basis of catalytic activity on the polymer surface by different techniques. The cyclic voltammograms showed two distinct ORR peaks, indicating two different active sites. This was also in agreement with Mulliken charge distribution from DFT studies, which showed the presence of two different carbons next to nitrogen having different electropositive nature