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Stancovski V.,LogiCoul Solutions LLC | Badilescu S.,Concordia University at Montreal
Journal of Applied Electrochemistry | Year: 2014

In this review, the recent advances in the development of in situ Raman spectroscopy and electrochemical techniques and their application for the study of lithium-ion batteries are revisited. It is demonstrated that, during a relatively short period of time (1995-2013), the spectroelectrochemical techniques used for the investigation of battery components, benefited directly from the tremendous advances of Raman technology. The most important step was the implementation of confocal Raman microscopy in the battery research, which opened the way to new and more sophisticated applications. This review shows how the discovery of new Raman techniques such as surface-enhanced Raman scattering, tip-enhanced Raman spectroscopy, spatially offset Raman spectroscopy as well as the integration of Raman spectrometers into non-optical microscopes, for example AFM and SEM, allowed to perform two or more analytical techniques on the same sample region, with an exceptionally high resolution. All these progresses led to new insights into battery materials and components such as electrodes and electrolytes, and helped to understand the electrode/electrolyte interface phenomena. This enhanced understanding allowed a deeper insight into important phenomena, as e.g., battery aging and the dynamic nature of the solid electrolyte interfaces in lithium batteries. The high relevance of the information provided by these techniques in the progress of battery modeling is another positive contribution. Another area of high practical significance for the battery field is the screening of electrode materials, which is facilitated by the availability of the data provided by spectroscopic methods. © 2013 Springer Science+Business Media Dordrecht. Source


Almoabadi A.,Concordia University at Montreal | Badilescu S.,Concordia University at Montreal | Truong V.-V.,Concordia University at Montreal | Alsawafta M.,American University of Kuwait | And 3 more authors.
2015 Photonics North | Year: 2015

Due to its lithium ion intercalation capability, vanadium pentoxide is extensively studied for applications such as electrode material for pseudocapacitors, electrochromic devices, and cathodes in high capacity lithium ion batteries. Vanadium oxide has a layered structure and, in order to enhance lithium ion intercalation, templating methods are proposed in this work to create porosity in the film. The aim of this work is to evaluate how the morphology of vanadium pentoxide thin films is instrumental in obtaining a material with a high lithium ion intercalation capacity. With an appropriate morphology, the performance of vanadium oxide as electrochromic material and as cathode in lithium ion batteries can be improved significantly. For this purpose, both layered (dense and porous) and nanorod films were prepared and characterized. Scanning electron microscopy, cyclic voltammetry and electrical impedance spectroscopy measurements were used for the characterization of the different V2O5 films. The results showed the very good electrochromic properties of the porous film built up with polystyrene microspheres and triblock copolymer as templating materials as well as of the nanorod films fabricated by thermal annealing. © 2015 IEEE. Source


Almoabadi A.,Concordia University at Montreal | Alsawafta M.,Concordia University at Montreal | Alsawafta M.,American University of Kuwait | Badilescu S.,Concordia University at Montreal | And 4 more authors.
Journal of Nanomaterials | Year: 2016

Vanadium pentoxide sol-gel prepared thin films were deposited on indium-tin-oxide (ITO) substrates by dip-coating at a subzero temperature (-10°C). The structure, morphology, and optical and electrochromic properties of dense and porous vanadium oxide films coated at low temperature were determined and compared to those of the corresponding films deposited under room-temperature conditions. The results indicated that, in the films coated at-10°C, a residual compressive stress exists that would originate from the formation of microvoids during the deposition. These microvoids are preserved during the heat treatment of the films. The microvoid morphology would favor the formation of nanostructures that would be responsible for the improved electrochromic properties of the subzero dip-coated films. Low-temperature coated films, heated at 450°C for several hours, undergo the transformation from a layered to a highly uniform nanorod structure that would be an important feature for different applications. © 2016 Afaf Almoabadi et al. Source


Mosaddeghian Golestani Y.,Concordia University at Montreal | Mosaddeghian Golestani Y.,Kent State University | Alsawafta M.,American University of Kuwait | Badilescu S.,Concordia University at Montreal | And 2 more authors.
Journal of the Electrochemical Society | Year: 2014

Nanostructured tungsten oxide films for electrochromic applications are fabricated by using a new method - vacuum filtration and transfer onto Indium Tin Oxide (ITO) substrates. It is found that the thickness and morphology of the film depend on the size of nanoparticles, the amount of the filtrated material, the pore size of the membrane, and the temperature of the post-deposition heat-treatment. The films show interesting and quite unexpected electrochromic properties, especially regarding the response time. Compared to films fabricated through sol-gel methods, the response time, especially, the bleaching time, is considerably shorter, in spite of the larger thickness of the filtrated films. As shown by chronoamperometry measurements, the bleaching process is considerably faster than the coloring. This characteristic is reinforced by the diffusion coefficients calculated from both cyclic voltammetry and electrical impedance spectroscopy data. The vacuum filtration method proved to be well-suited for the fabrication of electrochromic films based on single materials and can be easily extended to doped materials and mixtures. © 2014 The Electrochemical Society. Source


Alsawafta M.,Concordia University at Montreal | Golestani Y.M.,Concordia University at Montreal | Phonemac T.,Concordia University at Montreal | Badilescu S.,Concordia University at Montreal | And 2 more authors.
Journal of the Electrochemical Society | Year: 2014

Macroporous tungsten oxide thin films were prepared by using a polystyrene microsphere template and the peroxitungstic acid precursor. Gold nanoparticles were introduced into the tungsten oxide film by two different methods, either in the polystyrene template, through a self-assembly process, or they were cast on the surface of the annealed film. Raman imaging experiments showed an enhancement effect of the intensity of the major tungsten oxide bands by the gold nanoislands. The electrochromic properties of gold-doped macroporous tungsten oxide are described and compared to those of the standard porous sol-gel film. The films with gold nanoparticles on the surface of the tungsten oxide film were found to have better electrochromic properties than the standard sol-gel tungsten oxide films and the ones doped with gold in the polystyrene template. The diffusion coefficients of protons in the gold-doped tungsten oxide films were determined from both Cyclic Voltammetry (CV) and Electrical Impedance Spectroscopy (EIS) measurements. The results indicate a faster diffusion of the proton in the porous film, compared with a compact tungsten oxide film. The model that evolves from the EIS data, involves fast charge transfer rates at the electrolyte/tungsten oxide film interface. The results demonstrated an enhancement of the coloration efficiency of the macroporous tungsten oxide films with Au nanoparticles on the surface of the film. The possible involvement of plasmon resonance of Au nanoparticles in the electrochromic process is discussed. © 2014 The Electrochemical Society. All rights reserved. Source

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