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515. Electrochemical and Thermal Studies of Carbon-Coated LiFePO[sub 4] Cathode

Author

Karim Zaghib, Jai Prakash, Humberto Joachin, and Thomas D. Kaun

Subjects
Renewable Energy, Sustainability and the Environment, Chemistry, Analytical chemistry, Condensed Matter Physics, Electrochemistry, Cathode, Isothermal process, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, law.invention, Calorimeter, Dielectric spectroscopy, Differential scanning calorimetry, Chemical engineering, law, Heat generation, Electrode, Materials Chemistry
Abstract

The carbon-coated LiFeP0 4 Li-ion cathode material was studied for its electrochemical and thermal performance. This electrode exhibited a reversible capacity corresponding to more than 90% of the theoretical capacity when cycled between 2.5 and 4.0 V. The material also showed good capacity retention at high powers, implying that the carbon coating improves the electronic conductivity and hence the cycling of this material. The diffusion coefficient of this material was calculated from its electrochemical impedance spectroscopy. The heat generation during charge and discharge was studied using an isothermal microcalorimeter. Thermal studies were also investigated by using a differential scanning calorimeter and an accelerating rate calorimeter, which showed that LiFePO 4 is safer than the commonly used lithium metal oxide cathodes with layered structures.

Published
2009
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521. LiFePO4 Surface Reactivity

Author

Karim Zaghib, Abdelbast Guerfi, Patrick Charest, Martin Dontigny, Jean-Francois Labrecque, Alain Mauger, Monika Kopec, Francois Gendron, and Christian M. Julien

Abstract

not Available.

Published
2008
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532. Electronic Structure of the Electrochemically Delithiated Li[sub 1−x]FePO[sub 4] Electrodes Investigated by P K-edge X-Ray Absorption Spectroscopy

Author

Won-Sub Yoon, Kyung Yoon Chung, Xiao-Qing Yang, James McBreen, and Karim Zaghib

Subjects
X-ray absorption spectroscopy, Materials science, Absorption spectroscopy, General Chemical Engineering, Analytical chemistry, chemistry.chemical_element, Electronic structure, Electrochemistry, K-edge, chemistry, Covalent bond, General Materials Science, Lithium, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, Inductive effect
Abstract

P K-edge X-ray absorption spectroscopy (XAS) has been carried out to investigate the electronic structure of the electrochemically delithiated Li{sub 1-x}FePO{sub 4} for Li rechargeable batteries. The gradual shift of main edge features to higher energy side showed that P-O bonds become less covalent during delithiation due to the more covalent Fe{sup 3+}-O bonds via the inductive effect. A principal component analysis of P K-edge XAS spectra of the electrochemically delithiated Li{sub 1-x}FePO{sub 4} reveals that this set of spectra can be well represented by two primary components, in good agreement with a first-order phase transition involving the LiFePO{sub 4} and FePO{sub 4} phases. From the observation of pre-edge peaks, it is concluded that electrochemical delithiation of Li{sub 1-x}FePO{sub 4} results in the hybridization of P 3p states with the Fe 3d states.

Published
2006
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533. Effect of Carbon Source as Additives in LiFePO[sub 4] as Positive Electrode for Lithium-Ion Batteries

Author

Patrick Charest, Abdelbast Guerfi, Karim Zaghib, Joongpyo Shim, and K. A. Striebel

Subjects
Materials science, General Chemical Engineering, chemistry.chemical_element, Carbon black, Electrochemistry, Cathode, law.invention, chemistry, Chemical engineering, law, Electrical resistivity and conductivity, Electrode, General Materials Science, Lithium, Graphite, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, Carbon
Abstract

The electrochemical properties of LiFePO4 cathodes with different carbon contents were studied to determine the role of carbon as conductive additive. LiFePO4 cathodes containing from 0 to 12% of conductive additive ~carbon black or mixture of carbon black and graphite! were cycled at different C rates. The capacity of the LiFePO4 cathode increased as conductive additive content increased. Carbon increased the utilization of active material and the electrical conductivity of electrode, but decreased volumetric capacity of electrode. This composition ~LiFePO4 with 3 wt % of carbon and 3 wt % of Graphite! is suitable for HEV application.

Published
2005
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534. Effect of Graphite Particle Size on Irreversible Capacity Loss

Author

Karim Zaghib, Gabrielle Nadeau, and Kimio Kinoshita

Subjects
Renewable Energy, Sustainability and the Environment, Mineralogy, chemistry.chemical_element, Electrolyte, Condensed Matter Physics, Decomposition, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Electrochemical cell, Chemical engineering, chemistry, Electrode, Materials Chemistry, Electrochemistry, Graphite, Particle size, Capacity loss, Carbon
Abstract

Electrolyte decomposition and irreversible capacity loss (ICL) occur on carbon electrodes in Li‐ion cells. The nature of the surface sites and their role in the amount of electrolyte decomposition on carbon electrodes is not fully understood. Therefore, a study was undertaken to analyze the relationship between the ICL and the active sites on natural graphite of prismatic structure. The ICL was measured on natural graphite of predominantly two‐dimensional platelets of average particle size varying from 2 to 40 μm. The fraction of edge and basal plane sites was determined for ideal prismatic structures of different particle size and used as a model for the natural graphite particles. This analysis permitted an analysis of the relationship between the electrolyte decomposition and the distribution of surface sites. From this analysis we conclude that these sites play an important role in the magnitude of the irreversible capacity loss on natural graphite. © 2000 The Electrochemical Society. All rights reserved.

Published
2000
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536. Electrochemical features of Li-Ni-Mn-Co oxides

Author

Karim Zaghib, H. Abbas, Chintalapalle V. Ramana, Christian M. Julien, A. E. Eid, Francois Gendron, Alain Mauger, Ashraf Adbel-Ghany, and Ahmed M. Hashem

Subjects
Materials science, Intercalation (chemistry), Inorganic chemistry, chemistry.chemical_element, Electrochemistry, Cathode, law.invention, chemistry, law, Electrode, Gravimetric analysis, Lithium, Sol-gel, Voltage
Abstract

We report the electrochemical behavior of various layered oxides in Li cells. A series of LiNiyMnyCozO2 materials (with z=1-2y) was synthesized by “chimie douce” and investigated as positive electrodes in rechargeable lithium batteries. Electrochemical performances of LiNiyMnyCozO2 oxides are tested cell using non-aqueous 1M LiPF6 dissolved in EC-DEC. Charge discharge profiles are investigated as a function of the rate capability, the voltage window and the synthesis parameters of the cathode. A relation is found between the gravimetric capacity and the cation disorder of materials as indicated by magnetometry analysis.

537. Identification of the active triple-phase boundary of a non-Pt catalyst layer in fuel cells.

Author

Yu-Cheng Wang, Wen Huang, Li-Yang Wan, Jian Yang, Rong-Jie Xie, Yan-Ping Zheng, Yuan-Zhi Tan, Yue-Sheng Wang, Karim Zaghib, Li-Rong Zheng, Shu-Hui Sun, Zhi-You Zhou, and Shi-Gang Sun

Subjects
*OXYGEN reduction, *PROTON exchange membrane fuel cells, *PLATINUM catalysts, *FUEL cells, *ELECTRODES in proton exchange membrane fuel cells, *CATALYSTS
Abstract

The article presents an electrochemistry research study on identification of triple-phase boundary of a non-Pt catalyst layer in fuel cells. Topics include rational design of non-Pt oxygen reduction reaction catalysts and catalyst layers in fuel cells is impeded by insufficient knowledge of triple-phase boundaries (TPBs) in the micropore and mesopore range; and concept of inactive TPBs provides a previously unidentified design principle for non-Pt catalyst and catalyst layers in fuel cells.

Published
2022
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538. Hydro thermal synthesis and electrochemical characterization of (V1/2Sb1/2Sn)O4 and (Fe1/2Sb1/2Sn)O4 as energy storage materials.

Author

R., Anil Kumar M., Elim, Hendry Izaac, Idris, Mohd Sobri, Yuwono, Akhmad Herman, Yuliarto, Brian, Rompas, P. T. D., Barzinjy, Azeez Abdullah, Hamed, Fathalla, Jose, Rajan, Karim, Zaghib, and Reddy, M.V.

Subjects
*HYDROTHERMAL synthesis, *ENERGY storage, *ANODES, *HEAT treatment, *CYCLIC voltammetry
Abstract

This paper reports the hydrothermal synthesis of alloy anode materials (V1/2Sb1/2Sn)O4 and (Fe1/2Sb1/2Sn)O4 and determine the effect of heat treatment on reversible capacities of the two oxides, and evaluation of their electrochemical properties. The compounds were initially prepared using the hydrothermal method at 180°C, and part of the active materials were reheated at 500°C in the air to improve the crystallinity and reduce the impurities. The materials were characterized by X-ray diffraction, scanning electron microscopy (SEM), Raman spectroscopy, and BET surface area. Anodic electrochemical behavior was examined by cyclic voltammetry (CV), galvanostatic cycling, and electrochemical impedance spectroscopy (EIS). Results show that (Fe1/2Sb1/2Sn)O4 reheated at 500°C delivers a better capacity of ∼400 mAh/g at 0.005-1.0 V voltage range up to 60th cycle. When we cycled a higher cut-off voltage of 0.005-3.0V, higher reversible capacity and higher capacity fading were noted due to alloying and conversion reaction of these mixed oxides. Cyclic voltammetry studies show reversible alloying/de-alloying peaks at ∼0.25 and ∼0.5 V vs. Li [ABSTRACT FROM AUTHOR]

Published
2021
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539. Molten salt synthesis of CoFe2O4 and its energy storage properties.

Author

Kulkarni, Pranav, Balkrishna, R. Geetha, Ghosh, Debasis, Rawat, R.S., Medwal, Rohit, Chowdari, B.V.R., Karim, Zaghib, and Reddy, M.V.

Subjects
*ENERGY storage, *FUSED salts, *LITHIUM-ion batteries, *RIETVELD refinement, *TRANSMISSION electron microscopy, *METAL nanoparticles
Abstract

In this article, we report simple and scalable one-pot molten salt synthesis of CoFe 2 O 4 as electrode material for Lithium ion batteries. X-ray diffraction studies along with Rietveld analysis showed a pure phase of CoFe 2 O 4 with space group Fd-3m and crystallite size of 54 nm. As an anode material CoFe 2 O 4 showed high initial discharge/charge capacity of 1556/1093 mA h g−1 and a reversible capacity of 926 mA h g−1 after 30 cycles with columbic efficiency of 99%. A relatively high reversible capacity of 594 mA h g−1 was observed at high current density of 1C (916 mA g−1) which shows the better reversibility of CoFe 2 O 4 at high current density. As the current was reduced to 0.1C reversible capacity of 899 mA h g−1 was retained suggesting high rate performance of CoFe 2 O 4. The long-term stability test, carried out using galvanostatic charge/discharge (GC) at a current density of 0.5C, showed a reversible capacity of 369 mA h g−1 at the end of 200th cycle. The structural and morphological evaluation of the sample after cycling, using ex-situ X-ray diffraction and ex-situ transmission electron microscopy, confirmed structural degradation and formation of metal nanoparticles, Li 2 O and amorphous nature of electrode material. The one-pot molten salt synthesis approach is quite simple and can be extended for large-scale production of electrode materials. Image 1 • One Pot molten salt synthesis of CoFe 2 O 4. • Uniform Cubic morphology was obtained without any use of surfactants. • Good reversible capacity of 540 mA h g−1 was obtained at 1C. • Ex-situ XRD and TEM showed the structural destruction and amorphous nature after cycling. [ABSTRACT FROM AUTHOR]

Published
2021
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540. Electrochromic properties of modified NiO thin films

Author

MOULKI, Hakim, STAR, ABES, Aline Rougier, Guy Campet, Mario Maglione [Président], Frédéric Le Cras [Rapporteur], Karim Zaghib [Rapporteur], Corinne Marcel, Rougier, Aline, Campet, Guy, Le Cras, Frédéric, Zaghib, Karim, Marcel, Corinne, and Maglione, Mario

Subjects
[CHIM.MATE] Chemical Sciences/Material chemistry, Electrochromic devices, Couches minces, Lithium free Ionic liquid, Thin films, Oxyde de nickel modifié, Dispositifs électrochromes, Coloration neutre, Liquides ioniques non lithiés, Modified Nickel oxide, Neutral color
Abstract

Electrochromic devices, ECDs, are able to change their optical properties under an applied voltage. In the framework of the European project INNOSHADE, the aim of the current work is the development of neutral color ECDs based on nickel oxide thin films as counter electrode. Ni3+ containing NiO thin films, called modified NiO thin films, were deposited both by Pulsed Laser Deposition and chemical route. When cycled in lithium based electrolyte, the comparison of the EC behavior of non-stoichiometric NiO thin films points out a higher electrochemical capacity associated with a larger optical contrast for the films synthesized by chemical route due in particular to a larger porosity. Highlighting a novel approach, herein we demonstrate faster kinetics for modified NiO thin films cycled in lithium ion free electrolyte and suggest the participation of anions. High electrochromic efficiency and nice durability of all-solid state devices associating modified NiO and WO3 or Poly(3,4 –ethylenedioxythiophene) PEDOT layers are reported., Ce travail de thèse a été réalisé dans le cadre du programme européen INNOSHADE, dont l’objectif était la réalisation de dispositifs électrochromes à coloration neutre. Cette coloration neutre est le résultat de l’association dans un même dispositif de la couleur marron de films à base d’oxyde de nickel avec celle bleue de films d’oxyde de tungstène ou de PEDOT. Nos recherches ont été orientées vers des films minces d’oxyde de nickel modifié contenant des ions nickel trivalent, alliant porosité et désordre structural. Deux techniques de dépôt ont été utilisées : l’ablation laser et le trempage-retrait (dip-coating). Des processus de coloration et de décoloration de ces films en milieux liquides ioniques hydrophobes lithiés et non lithiés, faisant intervenir la participation d’anions tels que TFSI-, ont été mis en évidence pour la première fois dans cette thèse. Les dispositifs tout solides correspondants présentent des efficacités optiques élevées et une bonne durabilité.

Published
2013

541. Capacity Contribution Induced by Pseudo-Capacitance Adsorption Mechanism of Anode Carbonaceous Materials Applied in Potassium-ion Battery.

Author

Liu J, Xu Z, Wu M, Wang Y, and Karim Z

Abstract

The intrinsic bottleneck of graphite intercalation compound mechanism in potassium-ion batteries necessitates the exploitation of novel potassium storage strategies. Hence, utmost efforts have been made to efficiently utilize the extrinsic pseudo-capacitance, which offers facile routes by employing low-cost carbonaceous anodes to improve the performance of electrochemical kinetics, notably facilitating the rate and power characteristics for batteries. This mini-review investigates the methods to maximize the pseudo-capacitance contribution based on the size control and surface activation in recent papers. These methods employ the use of cyclic voltammetry for kinetics analysis, which allows the quantitative determination on the proportion of diffusion-dominated vs. pseudo-capacitance by verifying a representative pseudo-capacitive material of single-walled carbon nanotubes. Synergistically, additional schemes such as establishing matched binder-electrolyte systems are in favor of the ultimate purpose of high-performance industrialized potassium-ion batteries., (Copyright © 2019 Liu, Xu, Wu, Wang and Karim.)

Published
2019
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