TiO₂ Nanoparticles Prepared by Sol-Gel Method for Anode Application in Lithium-Ion Batteries

TiO 2 nanoparticles are prepared via sol-gel method using titanium tetraisopropoxide (TTIP) as a precursor under refluxing and controlled pH. It is found that pure anatase phase is obtained with pH 10. Further characterization studies are carried out on pure nanoparticle anatase phase by XRD, SEM, and transmission electron microscope (TEM). Their electrochemical performances as anode material in lithium-ion batteries are investigated by cyclic voltammetry, galvanostatic cycling, and rate capability measurements. A high discharge capacity of 321 mAh/g (vs. 335 mAh/g theoretical) is achieved at 1C rate. After the first galvanostatic charge/discharge cycle, voltage profiles show plateaus at 1.75 and 1.95 V versus Li at discharge and charge, respectively. High Coulombic efficiency (>99%) is maintained after 300 cycles, which makes anatase TiO 2 nanoparticles prepared by sol-gel method, a very promising material for anode application in lithium rechargeable batteries

Mechanical characterization of an electrostrictive polymer for actuation and energy harvesting

Electroactive polymers have been widely used as smart material for actuators in recent years. Electromechanical applications are currently focused on energy harvesting and actuation, including the development of wireless portable electronic equipment autonomous and specific actuators such as artificial muscles. The problem to be solved is to make its devices the most efficient, as possible in terms of harvested energy and action. These two criteria are controlled by the permittivity of the electrostrictive polymer used, the Young\u27s modulus, and their dependence on frequency and level of stress. In the present paper, we presented a model describing the mechanical behaviour of electrostrictive polymers with taking into account the mechanical losses. Young\u27s modulus follows a linear function of strain and stress. However, when the elongation becomes higher, the data obtained from this strain linear trend and significant hysteresis loops appear the reflections on the existence of mechanical losses. In this work, to provide the analysis of the experimental observations, we utilized a theoretical model in order to define a constitutive law implying a representative relationship between stress and strain. After detailing this theoretical model, the simulation results are compared with experimental ones. The results show that hysteresis loss increases with the increase of frequency and strain amplitude. The model used here is in good agreement with the experimental results

Enhancement of electrostrictive polymer efficiency for energy harvesting with cellular polypropylene electrets

The purpose of this paper is to propose new means for harvesting energy using electrostrictive polymers. The recent development of electrostrictive polymers has generated new opportunities for high-strain actuators. At the current time, the investigation of using electrostrictive polymer for energy harvesting, or mechanical-to-electrical energy conversion, is beginning to show its potential for this application. The objective of this work was to study the effect of cellular polypropylene electrets after high-voltage corona poling on an electrostrictive polyurethane composite filled with 1 vol.% carbon black at a low applied voltage in order to increase the efficiency of the electromechanical conversion with electrostrictive polymers. Theoretical analysis supported by experimental investigations showed that an energy harvesting with this structure rendered it possible to obtain harvested power up to 13.93 nW using a low electric field of 0.4 V/mu m and a transverse strain of 3% at a mechanical frequency of 15 Hz. This represents an efficiency of 78.14% at low frequency. This percentage is very significant compared to other structures. Finally, it was found that the use of polypropylene electrets with electrostrictive polymers was the best way to decrease the power of polarization in order to obtain a good efficiency of the electromechanical conversion for energy harvesting

Long jumps contribution to the adatom diffusion process near the step edge: The case of Ag/Cu(110)

In this work, the diffusion of a single Ag adatom on a low-index Cu surface (110) in the presence of a step edge is studied using the embedded-atom method (EAM). Molecular static simulation is carried out in order to calculate the activation energy of different diffusion processes. Our findings are in a good agreement with results existing in the literature indicating that adatom diffusion via jump process is more favored than the other mechanisms. The activation energy corresponding to diffusing via hopping is found to be 0.25 eV (at 0 K). On the other hand, the activation barrier calculated by molecular dynamics (MD) simulation for a large range of temperature (310–500 K) is found to be around 0.25 eV for both upper and lower position leading to a good agreement between static and dynamic calculations. The prefactor for Ag adatom self-diffusion via hopping on Cu(110) surface near the step edge is examined. The results show that the prefactors are 2.7 and 3.6 × 104 cm2 s−1 for the upper and lower position, respectively. This is in line with the value of 10−3 cm2 s−1 that is generally adopted. We also found that long jumps occur frequently in this system and their contribution cannot be neglected

New insights into the electrochemical and thermodynamic properties of AB-type ZrNi hydrogen storage alloys by native defects and H-doping: Computational experiments

International audienc

Analysis of micro power generator autonomous PZT with use of sliding mode control

International audienceResearch on energy harvesting and related technologies have attracted attention and have shown their potential in a wide range of applications, the portable electronic devices (numerical telephones, diaries, microcomputers, watches, medical prostheses...) accompany us, often in a banal way, in the everyday life; they render very many services to us but, because of their insufficient autonomy, also force us in our desires of mobility and autonomy. Many mechanisms of energy conversion and device designs for vibration-based energy harvesting have been developed and reported in literature, In addition to electromagnetic and electrostatic mechanisms that have been widely applied, many other mechanisms such as electrostrictive and dielectric polymers have also been investigated. The power optimality performance of a piezoelectric energy harvester connected to a resistive load is studied. An analytical solution for the piezoelectric energy harvester based on the piezoelectric constitutive equations and the fundamental mechanics of materials relations is adapted to estimate the optimal power and vibration amplitude. The influence of geometrical parameter on the stack piezoelectric is also investigated. The power harvesting in a pressure-loaded plate depends on several factors. The dominant parameters that affect the performance are the ratio of thickness layer and the area of electrode, a designated power management module for sub mW energy harvester is proposed in this article to increase the energy conversion efficiency and extend the energy storage Life time for small input power, with use sliding mode control The specimen was simulate under tow values ratio of thickness layer and the area 1/0.09 and 0.1/0.01. The measured output voltages for two different ration is 8V and The results indicate that the electricity power output has 2.2 mW

Recent advances in magnesium hydride for solid-state hydrogen storage by mechanical treatment: A DFT study

International audienc

PU/PZT composites for vibratory energy harvesting

cited By 3International audiencePiezoelectric composites of PU/PZT with 0–3 connectivity were prepared in the film form. Homogeneous dispersion of the ceramic PZT in polyurethane matrix has been obtained and has been verified by SEM analysis. Dielectric properties reveal that under an electrical field of 1000 V the remnant polarization increased from 1.9 to 4 µC/cm−2 when the volume fraction of PZT increased from 50 to 80 %. Modeling and vibratory energy harvesting tests has been realized. At very low frequency and deformation, and without application of any static electric field, 1.15 µW of power has been obtained. The results obtained in this work contribute to demonstrate the ability of the incorporation of PZT particles in the polymer matrix to improve the conversion efficiency of the vibratory energy into electrical energy for the development of µ-generators. © 2016, Springer Science+Business Media New York

Engineering the hydrogen storage properties of the perovskite hydride ZrNiH3 by uniaxial/biaxial strain

International audienc

Enhanced thermodynamic properties of ZrNiH3 by substitution with transition metals (V, Ti, Fe, Mn and Cr)

International audienc