References of "Job, Nathalie"
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See detailCarbon gels for electrochemical applications
Job, Nathalie ULiege

in Prassas, Michel; Aegerter, Michel (Eds.) Carbon gels: from synthesis to applications (in press)

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See detailSi-Doped Carbon Xerogels for Li/Na-ion Batteries
Carabetta, Joseph ULiege; Job, Nathalie ULiege

Poster (2019, May 30)

The use of dopants such as silicon, tin, and, more recently, antimony in carbonaceous anodes is a promising area of research to increase the performance of lithium and sodium ion batteries [1-3]. The ... [more ▼]

The use of dopants such as silicon, tin, and, more recently, antimony in carbonaceous anodes is a promising area of research to increase the performance of lithium and sodium ion batteries [1-3]. The biggest obstacle to the progress of this technology is the stability of these inclusions in the carbon material during charging and discharging, most notably the volume change of the active material [4-8]. An electrode design was synthesized that consists of a carbon xerogel via a sol-gel process (CX), which acts as a support structure for a dopant, silicon nanoparticles (SiNPs), and provides electronic conductivity. Syntheses have been made using poly(sodium 4-styrenesulfonate) (PSS) as a coating or binder. These syntheses showed positive results on the cyclability of the CX/SiNPs composite. A 5-fold increase was observed in the number of charge/discharge cycles before the reversible capacity was less than 80% the initial capacity when compared with a composite with no coating and conventional binder. The gradual loss in capacity in the coated composite is still unknown, but may be due to the interplay between SEI formation and the volume expansion of the SiNPs. These problems are now being addressed by various techniques to improve the chemical and mechanical stability, and tailoring the microporosity and mesoporosity to reduce the irreversibly capacity loss and increase the accessibility to the dopant material. References: [1] W. Luo et al. Journal of Power Sources 304 (2016) 340–345 [2] B. Guo et al. Journal of Power Sources 177 (2008) 205–210 [3] RSC Advances, 2012, 2, 4311–431 [4] W.J. Zhang, J. Power Sources 196 (2011) 13–24 [5] H. Wu, Y. Cui, Nano Today 7 (2012) 414–429. [6] L.Y. Beaulieu, K.W. Eberman, R.L., et al. Electrochem. Solid-State Lett. 4 (2001) A137–A140. [7] J.H. Ryu, J.W. Kim, et al. Electrochem. Solid-State Lett. 7 (2004) A306–A309. [8] M.A. Rahman, G. Song, A.I. Bhatt, et al. Adv. Funct. Mater. 26 (2016) 647–678. [less ▲]

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See detailTunable carbon-supported catalyst materials processed by low-pressure plasma treatments of solid precursors
Pireaux, Jean-Jacques; da Silva Pires, Mathieu; Bocchese, Fabrice et al

Conference (2019, February)

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See detailInsights on palladium decorated nitrogen-doped carbon xerogels for the hydrogen production from formic acid
Navlani-Garcia, Miriam; Salinas-Torres, David; Mori, Kohsuke et al

in Catalysis Today (2019), 324

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See detailState of health estimation for lithium ion batteries based on an equivalenthydraulic model: An iron phosphate application
Couto, Luis; Schorsch, Julien; Job, Nathalie ULiege et al

in Journal of Energy Storage (2019), 21

A two-step approach for state-of-health (SOH) estimation of a lithium-ion (Li-ion) battery is developed. In the first step, state-of-charge (SOC) estimation is performed by a constrained extended Kalman ... [more ▼]

A two-step approach for state-of-health (SOH) estimation of a lithium-ion (Li-ion) battery is developed. In the first step, state-of-charge (SOC) estimation is performed by a constrained extended Kalman filter (EKF) based on the so-called equivalent-hydraulic model. The latter model allows to characterize the internal battery state and main physical parameters while being suitable for on-line computation. The internal battery states are further exploited in the second step of the approach to obtain parameter-based SOH indicators that characterize the long term evolution of the diffusion and charge transfer processes associated to aging. Capacity and power fade indicators are determined by using notably an instrumental variable method in order to obtain unbiased parameter estimates in the presence of heteroscedastic colored noise. The methodology is validated on both simulation and experimental data for a lithium iron phosphate (LFP) half battery cell. This also provides insight on the properties of the LFP electrodes [less ▲]

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See detailSafe and green Li-ion batteries based on LiFePO4 and Li4Ti5O12 sprayed as aqueous slurries with xanthan gum as a common binder
Léonard, Alexandre ULiege; Job, Nathalie ULiege

in Materials Today Energy (2019), 12

Li-ion batteries based on LiFePO4 positive electrodes and Li4Ti5O12 negative electrodes, both processed via an aqueous slurry preparation pathway, are presented. In this respect, xanthan gum, a cheap and ... [more ▼]

Li-ion batteries based on LiFePO4 positive electrodes and Li4Ti5O12 negative electrodes, both processed via an aqueous slurry preparation pathway, are presented. In this respect, xanthan gum, a cheap and water-soluble polysaccharide, is shown to be a suitable binder for both electrodes, allowing for a simplified and common preparation method. The electrodes, obtained by spray-coating, show an improved adhesion to the current collectors. The performance of the water-processed electrodes have been investigated in half-cells and compared to similar electrodes prepared upon using PVDF as a binder and N-methyl-pyrrolidone as a solvent. Electrochemical characterizations point to similar performance in terms of (dis-)charge capacities and a good cycling stability. Full-cells based on the obtained electrodes also show stable cycling, with a capacity of ~110 mA.h/g at C/2. The procedure was further extended to the use of stainless-steel as current collectors, with similar results in terms of electrochemical behavior. A relationship was established between the (dis-)charge capacity and the loading of active material for both the positive and negative electrodes, demonstrating the need to take this parameter into account when comparing data in terms of performance of the cells. Finally, the spent electrode substrates can easily be recycled upon immersion in water. [less ▲]

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See detailDisentangling the Degradation Pathways of Highly Defective PtNi/C Nanostructures - An Operando Wide and Small Angle X-ray Scattering Study
Asset, Tristan; Gommes, Cédric ULiege; Drnec, Jakub et al

in ACS Catalysis (2019), 9

Hollow bimetallic nanostructures are perfect systems to unravel the aging mechanisms of both Pt-based alloys and highly defective nanostructures used in proton-exchange membrane fuel cell (PEMFC) cathodes ... [more ▼]

Hollow bimetallic nanostructures are perfect systems to unravel the aging mechanisms of both Pt-based alloys and highly defective nanostructures used in proton-exchange membrane fuel cell (PEMFC) cathodes, since the mobility of their surface and bulk atoms leads to detectable chemical (i.e., Ni dissolution) and physical (i.e., decrease of the density of structural defects, collapse of the nanostructure, etc.) changes. In this study, we precisely and dynamically monitored these physicochemical changes on porous hollow PtNi/C nanoparticles during an aging procedure composed of 5000 potential cycles with linear ramps between 0.6 and 1.0 or 1.1 V vs RHE by using (i) synchrotron operando wide- and small-angle X-ray scattering (WAXS and SAXS), (ii) scanning transmission electron microscopy (STEM) in combination with X-ray energy dispersive spectroscopy (X-EDS), and (iii) electrochemical measurements. The synchrotron operando WAXS and SAXS results dynamically correlated the structural changes of the hollow NPs at both the atomic (Ni depletion, lattice parameter relaxation, variation in the density of structural defects, etc.) and nanometric (restructuring of the nanoparticles/collapse of the hollow nanostructure) level. They revealed that the collapse of the hollow nanostructure was always accompanied by a significant loss of the Ni content. The 0.6-1.1 V vs RHE aging protocol resulted in a more severe depreciation of the ORR associated with a larger restructuring of the nanoparticles in comparison to the 0.6-1.0 V vs RHE aging protocol, thus providing evidence that a critical potential exists for the stability of highly defective nanoalloys. [less ▲]

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See detailHow do the micropores of carbon xerogels influence their electrochemical behavior as anodes for lithium-ion batteries?
Piedboeuf, Marie-Laure; Léonard, Alexandre ULiege; Reichenauer, Gudrun et al

in Microporous and Mesoporous Materials (2019), 275

This work aims at shedding light on how the microporous texture of porous carbons influences their electrochemical behavior when used as anodes for Li-ion batteries. To this aim, a synthetic hard carbon ... [more ▼]

This work aims at shedding light on how the microporous texture of porous carbons influences their electrochemical behavior when used as anodes for Li-ion batteries. To this aim, a synthetic hard carbon (carbon xerogel, CX), prepared from a resorcinol-formaldehyde precursor gel, underwent several post-synthesis treatments in order to modulate its micropore to total pore volume ratio. The micropore volume was either expanded by physical activation or decreased using chemical vapor deposition (CVD) of a carbon layer. Several variables other than the micropore texture of the obtained carbons, which could influence their behavior as anode active materials for Li-ion batteries, such as the particle size or the electrode characteristics, were carefully controlled. The thickness of electrode coatings and the pore texture of the active material-binder composite were analyzed. It was shown that CX-binder composites resulting from water-based slurries preserve the microporosity of the starting materials. Detailed electrochemical characterization of the electrodes prepared with carbon xerogels displaying various defined micropore textures was performed. A clear linear dependency could be evidenced between the Li+ insertion and de-insertion in half-cell configuration with the increase of the volume of supermicropores (0.7 – 2 nm), demonstrating the effect of micropore enlargement by activation on the storage capacity, provided the maximum charge potential value is set at 3.0 V vs. Li+/Li. [less ▲]

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See detailCr/C multilayer coatings for proton exchange membrane fuel cell bipolar plate
Haye, Emile; Job, Nathalie ULiege; Deschamps, Fabien ULiege et al

Poster (2018, September)

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See detailSynthesis, characterization, and durability study of PtCo hollow nanoparticles deposited on carbon xerogel as electrocatalysts for Proton Exchange Membrane Fuel Cells
Zubiaur, Anthony ULiege; Asset, Tristan; Deschamps, Fabien ULiege et al

Poster (2018, July)

Proton exchange membrane fuel cell (PEMFC) catalysts are generally made of carbon black (CB)-supported platinum-based nanoparticles, and the PEMFC electrodes display high Pt loading (up to 0.5 mgPt/cm² ... [more ▼]

Proton exchange membrane fuel cell (PEMFC) catalysts are generally made of carbon black (CB)-supported platinum-based nanoparticles, and the PEMFC electrodes display high Pt loading (up to 0.5 mgPt/cm²) to reach high current without severe mass transport issues. To decrease the system cost, the decrease of the Pt mass contained in the PEMFC electrodes, in particular at the cathode where the oxygen reduction reaction (ORR) proceeds, remains a major challenge. Improving the mass activity of the catalyst towards ORR is currently best achieved by alloying Pt with 3d-transition metal atoms such as cobalt or nickel. These alloys perform better for the ORR because the substitution of some Pt atoms by 3d-metal atoms with smaller radius leads to a modified Pt electronic structure [1]. Therefore, the Pt loading of the electrode can be decreased by increasing the catalyst mass activity through alloying. Moreover, the properties of CBs, as described by Rodríguez-Reinoso [2], are not optimal for electrocatalysis; in particular, the electrode pore texture after processing (which includes hot-pressing) cannot be controlled. A possible solution to the drawbacks of CBs is the use of synthetic nanostructured materials with a controllable and reproducible pore texture and with a pure, known and constant chemical composition; carbon xerogels (CX) exhibit such properties [3]. Recently, various highly dispersed CX-supported Pt catalysts (Pt/CX), made of 3-4 nm metal nanoparticles, have been synthesized via several methods, such as the strong electrostatic adsorption (SEA), the charge enhanced dry impregnation (CEDI), or the liquid phase reduction of Pt ions with formic acid [4]. Their performances were found quite comparable to those of up-to-date commercial Pt/carbon black electrocatalysts. Another major challenge for the extensive worldwide commercialization of PEMFCs is the stability of the catalysts. Indeed, the stability of the Pt-based nanoparticles, as shown in Fig. 1a and 1b, has to be improved in order to increase the lifetime of PEMFCs [5]. A way to improve the durability of the catalyst is to use new and stable particle structures, such as hollow nanoparticles. The synthesis and performance of hollow PtCo nanoparticles/CX (Fig. 1c) are currently studied by our group. The synthesis consists in the formation of a Co nanoparticle colloid using citrate molecules as complexing agents, followed by the galvanic replacement of Co atoms by Pt ions and, then, by the diffusion of the remaining core Co atoms through/in the Pt shell. The results indicate that the ORR specific activity (expressed in A/mPt²) and the ORR mass activity (expressed in A/gPt) of the bimetallic hollow particles dispersed on CX are ca. 15 or 7 times higher than that of commercial pure Pt/CB, respectively. The durability of the hollow PtCo/CX catalyst was studied in a three-electrode cell and in a PEMFC electrode. In particular, accelerated stress tests (ASTs, i.e. 30,000 potential cycles between 0.6 and 1.0 V), performed in PEMFC assemblies, show that the hollow structure is stable: hollow particles present in the pristine catalyst (Fig. 1c) are still observed after cycling (Fig. 1d). Moreover, the performance of the cell constituted of the hollow PtCo/CX catalyst stabilizes: while Pt/C catalyst show a continuous performance drop, no further performance decrease is observed after the 10,000 first AST cycles, proving the good stability of this catalyst (Fig. 2). [less ▲]

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See detailDry plasma treatment of organometallic precursor for the synthesis of fuel cells catalyst material
da Silva Pires, Mathieu; Busby, Yan; Job, Nathalie ULiege et al

Poster (2018, July)

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See detailCatalytic layers of Proton Exchange Membrane Fuel Cells based on carbon xerogel supports
Job, Nathalie ULiege

Conference (2018, June 30)

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See detailCatalyseurs pour piles à combustible fabriqués par degradation plasma de précurseurs organométalliques
da Silva Pires, Mathieu; Busby, Yan; Haye, Emile et al

Conference (2018, June 05)

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See detailStreamlining of the synthesis process of Pt/carbon xerogel electrocatalysts with high Pt loading for the oxygen reduction reaction in proton exchange membrane fuel cells applications
Zubiaur, Anthony ULiege; Job, Nathalie ULiege

in Applied Catalysis B: Environmental (2018)

Pt/carbon xerogel catalysts were synthesized by different methods. The strong electrostatic adsorption (SEA) method, which consists in enhancing electrostatic interactions between the support and the ... [more ▼]

Pt/carbon xerogel catalysts were synthesized by different methods. The strong electrostatic adsorption (SEA) method, which consists in enhancing electrostatic interactions between the support and the precursor, was first modified in order to avoid any Pt loss (charge enhanced dry impregnation, CEDI). In a second step, the synthesis was rationalized to speed up the reduction (liquid phase reduction with sodium borohydride, NaBH4). The synthesis procedure was further simplified in order to obtain one-step procedures, such as (i) reduction of highly loaded platinum solution by sodium borohydride, (ii) formic acid reduction, and (iii) colloid synthesis. All the catalysts were analyzed by physicochemical and electrochemical methods. They are compared to a reference commercial catalyst (Tanaka). The best performances are obtained by the SEA, the CEDI and the formic acid reduced catalysts, the performance of which are at least equal to, or even higher (up to 20–25% in mass activity) than those of the commercial reference. From these three methods, the only one-step method is the formic acid reduction, which allows avoiding time-consuming drying and H2 reduction steps. [less ▲]

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See detailLes gels de carbone: de la maîtrise de la texture à l’amélioration de procédés
Job, Nathalie ULiege

Scientific conference (2018, May 30)

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See detailPorous hollow PtNi/C electrocatalysts: carbon support considerations to meet stability requirements
Asset, Tristan; Job, Nathalie ULiege; Busby, Yan et al

Conference (2018, May 13)

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See detailContinuous-porous N-doped carbon network as high-performance electrode for lithium-ion batteries
Alkarmo, Walid ULiege; Ouhib, Farid ULiege; Aqil, Abdelhafid ULiege et al

in Journal of Materials Science (2018), 53(8), 6135-6146

Hierarchical porous N-doped carbon (NPC) is prepared by pyrolysis of poly(- methyl methacrylate) (PMMA) particles decorated by graphene oxide (GO) and polypyrrole (PPy) as precursors and used as anode for ... [more ▼]

Hierarchical porous N-doped carbon (NPC) is prepared by pyrolysis of poly(- methyl methacrylate) (PMMA) particles decorated by graphene oxide (GO) and polypyrrole (PPy) as precursors and used as anode for lithium-ion batteries. The composite precursors with different diameter and composition (PMMA/GO/ PPy-A and B) were conveniently prepared by dispersion polymerization of methyl methacrylate in the presence of graphene oxide as stabilizer in aqueous medium, followed by addition of pyrrole and its oxidative polymerization. After pyrolysis, the resulting NPC composites with hierarchically structured macro- and mesopores exhibit high surface area (289–398 m2/g) and different N-doping levels (7.46 and 4.22 wt% of nitrogen content). The NPC with the highest N-doping level (7.46 wt%) shows high reversible capacities of 831 mAh/g at 74.4 mA/g (C/5) after 50 cycles and excellent rate performances. [less ▲]

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See detailAmbient oxidation of ultrasmall platinum nanoparticles on microporous carbon catalyst supports
Banerjee, Ritubarna; Chen, Donna; Karakalos, Stavros et al

in ACS Applied Nano Materials (2018), 1

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See detailPorous hollow PtNi/C electrocatalysts: carbon support considerations to meet performance and stability requirements
Asset, Tristan; Job, Nathalie ULiege; Busby, Yan et al

in ACS Catalysis (2018), 8

Detailed reference viewed: 28 (2 ULiège)