Development and tribological characterisation of nanostructured Zn-Ni and Zn-Co coatings: a comparative study

International audienceZn-Ni and Zn-Co alloy coatings were electrodeposited on mild steel from sulphate-based baths. The morphology, microstructure, microhardness and tribological behaviours of the coatings have been studied and discussed. While the Zn-5wt-% Co layers presented a nanocrystalline simple nodular structure (45 ± 5 nm), the Zn-14wt-% Ni showed a particular structure called cauliflower morphology (30 ± 7 nm). The X-ray diffraction analysis showed that each of the electrodeposits was formed from zinc solid solution with a uniform zinc-cobalt intermetallic phase γ 2 (CoZn 13) for Zn-5wt-% Co alloy. However, a single γ-phase (intermetallic compound Ni 5 Zn 21) was presented for the Zn-14wt-% Ni alloys. The Zn-14wt-% Ni films were found to be harder and rougher than the Zn-5wt-% Co layers. Plastic deformation and oxide layers production were the main wear mechanisms for the investigated coatings. The Zn-14wt-% Ni coatings were found to have the best wear resistance due to their microhardness and particular structure. ARTICLE HISTOR

Voltammetric determination of ascorbic acid with zinc oxide modified glassy carbon electrode

International audienc

Optical and Electrochemical Properties of Self-Organized TiO2 Nanotube Arrays From Anodized Ti−6Al−4V Alloy

Due to their high specific surface area and advanced properties, TiO2 nanotubes (TiO2 NTs) have a great significance for production and storage of energy. In this paper, TiO2 NTs were synthesized from anodization of Ti-6Al-4V alloy at 60 V for 3 h in fluoride ethylene glycol electrolyte by varying the water content and further annealing treatment. The morphological, structural, optical and electrochemical performances of TiO2 NTs were investigated by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), UV-Visible spectroscopy and electrochemical characterization techniques. By varying the water content in the solution, a honeycomb and porous structure was obtained at low water content and the presence of (α + β) phase in Ti-6Al-4V alloy caused not uniform etching. With an additional increase in water content, a nanotubular structure is formed in the (α + β) phases with different morphological parameters. The anatase TiO2 NTs synthesized with 20 wt% H2O shows an improvement in absorption band that extends into the visible region due the presence of vanadium oxide in the structure and the effective band gap energy (Eg) value of 2.25 eV. The TiO2 NTs electrode also shows a good cycling performance, delivering a reversible capacity of 82 mAh.g−1 (34 μAh.cm−2.μm−1) at 1C rate over 50 cycles

Direct Pre-lithiation of Electropolymerized Carbon Nanotubes for Enhanced Cycling Performance of Flexible Li-Ion Micro-Batteries

International audienceCarbon nanotubes (CNT) are used as anodes for flexible Li-ion micro-batteries. However, one of the major challenges in the growth of flexible micro-batteries with CNT as the anode is their immense capacity loss and a very low initial coulombic efficiency. In this study, we report the use of a facile direct pre-lithiation to suppress high irreversible capacity of the CNT electrodes in the first cycles. Pre-lithiated polymer-coated CNT anodes displayed good rate capabilities, studied up to 30 C and delivered high capacities of 850 mAh g −1 (313 μAh cm −2) at 1 C rate over 50 charge-discharge cycles

TiO2 Nanotubes with Nanograss Structure: The Effect of the Anodizing Voltage on the Formation Mechanism and Structure Properties

International audienc

Comportement électochimique de revêtements de nitrure d'aluminium élaborés par pulvérisation cathodique réactive

AIX-MARSEILLE1-BU Sci.St Charles (130552104) / SudocSudocFranceF

All-Solid-State Lithium Ion Batteries Using Self-Organized TiO2 Nanotubes Grown from Ti-6Al-4V Alloy

International audienceAll-solid-state batteries were fabricated by assembling a layer of self-organized TiO 2 nanotubes grown on as anode, a thin-film of polymer as an electrolyte and separator, and a layer of composite LiFePO 4 as a cathode. The synthesis of self-organized TiO 2 NTs from Ti-6Al-4V alloy was carried out via one-step electrochemical anodization in a fluoride ethylene glycol containing electrolytes. The electrodeposition of the polymer electrolyte onto anatase TiO 2 NTs was performed by cyclic voltammetry. The anodized Ti-6Al-4V alloys were characterized by scanning electron microscopy and X-ray diffraction. The electrochemical properties of the anodized Ti-6Al-4V alloys were investigated by cyclic voltammetry and chronopotentiometry techniques. The full-cell shows a high first-cycle Coulombic efficiency of 96.8% with a capacity retention of 97.4% after 50 cycles and delivers a stable discharge capacity of 63 µAh cm −2 µm −1 (119 mAh g −1) at a kinetic rate of C/10

Sputter-Deposited Amorphous LiCuPO 4 Thin Film as Cathode Material for Li-ion Microbatteries

International audienceWe report the electrochemical performance of amorphous LiCuPO 4 thin films obtained by radio frequency sputtering as a cathode material for Li-ion microbatteries. The thin films were characterized by X-ray diffraction, scanning electron micro-scopy, profilometry and electrochemical techniques. Charge/ discharge profiles and cycling performance were evaluated in lithium electrochemical test cells. Cyclic voltammogram of the LiCuPO 4 film shows the typical redox reaction peak at~1.9 V vs. Li/Li +. A discharge capacity of 160 mAh g À1 (50 mAh cm À2) is attained for the first cycle at C/10 to reach a stable capacity of 70 mAh g À1 (22 mAh cm À2) with good stability over 160 cycles. For comparison, the electrochemical performance of a crystalline LiCuPO 4 film was investigated. The first discharge could deliver a high capacity of around 375 mAh g À1 at C/10, but the capacity decayed quickly to a low capacity of 11 mAh g À1 over 50 cycles. The results show that the LiCuPO 4 amorphous materials can be considered as the exciting cathode candidate for Li-ion microbatteries

A humidity-sensitive nanocomposite solid ion conductor: sulfonated poly- ether-ether-ketone in nanotubular TiO2 or ZrO2 matrix CITATIONS 0 READS 95 Flexible and Stretchable Batteries View project Improving the corrosion resistance of electronic modules View project

International audienceA nanocomposite solid ion conductor was prepared by infiltrating zirconia or titania nanotube arrays, made by electrochemical anodization of Zr or Ti metal, with proton-conducting sulfonated poly(ether-ether-ketone) (SPEEK) ionomer. The resulting material was characterized using scanning electron microscopy, X-ray diffraction, and infrared spectroscopy showing the successful filling of the nanotubular matrix with the ionomer. Impedance spectroscopy revealed a conductivity increase by several orders of magnitude after infiltration; furthermore, the impedance of the TiO2nt-SPEEK nanocomposite is very sensitive to the relative humidity. Possible applications of these ionic conducting nanocomposites include solid-state humidity sensors or heterogeneous catalytic materials