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H Perrot - One of the best experts on this subject based on the ideXlab platform.
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scrutiny of the licoo2 composite electrode electrolyte interface by advanced Electrogravimetry and implications for aqueous li ion batteries
Journal of Physical Chemistry C, 2021Co-Authors: Wanli Gao, H Perrot, Christel Labertyrobert, Natacha Krins, Ozlem SelAbstract:The recent tendency in the battery field toward the use of aqueous electrolytes stimulated several studies searching for compatible electrode materials and charge carriers. Still, another aspect to...
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elucidating the origin of the electrochemical capacity in a proton based battery hxiro4 via advanced Electrogravimetry
ACS Applied Materials & Interfaces, 2020Co-Authors: Ozlem Sel, H Perrot, Pierre Lemaire, Daniel Alves Dalla Corte, Jeanmarie Tarascon, Antonella IadecolaAbstract:Recently, because of sustainability issues dictated by societal demands, more importance has been given to aqueous systems and especially to proton-based batteries. However, the mechanisms behind t...
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Ion Dynamics at the Single Wall Carbon Nanotube Based Composite Electrode/Electrolyte Interface: Influence of the Cation Size and Electrolyte pH
2019Co-Authors: F. Escobar-teran, H Perrot, O. SelAbstract:Electrochemical quartz crystal microbalance and ac-Electrogravimetry methods were employed to study ion dynamics in single wall carbon nanotube (SWCNT) based electrodes in various aqueous electrolytes and different electrolyte pH values. The pH dependence of the electroadsorption phenomena studied in NaCl at pH 2, pH 7, and pH 10 indicated that low and high pH values amplify the anion and cation contribution, respectively, which means that in the same potential range, the pH of the aqueous electrolyte is adjustable to preferentially electroadsorb cations or anions. The cation size dependence of the electrodeposition phenomena was also studied by changing the electrolyte cation from Li+, Na+ to K+. The results indicated that Li+ and Na+ species are more tightly bonded to their water molecules in their hydration shell compared to the potassium species; i.e., dehydration of K+ is easier than that of Na+ and Li+. K+ ions due their completely dehydrated state probably become equivalent to partially dehydrated Na+·nH2O, in terms of kinetics. Li+·nH2O ions dynamics is slower since it is much more difficult for them to get rid of their hydration shell, making their transfer the slowest among the other cations. Our electrogravimetric results clearly indicate that the dehydration affinity and the ions’ size play a role in the electroadsorption dynamics of the species on the SWCNT based composite electrodes
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Unveiling the ionic exchange mechanisms in vertically-oriented graphene nanosheet supercapacitor electrodes with electrochemical quartz crystal microbalance and ac-Electrogravimetry
Elsevier, 2018Co-Authors: D. Aradilla, H Perrot, G. Bidan, F. Billon, M. Delaunay, J.m. Gérard, O. SelAbstract:This work presents the first electrochemical quartz crystal microbalance (EQCM) results for vertically-oriented graphene nanosheets (VOGNs) as supercapacitor electrodes. Conventional EQCM technique delivered primary insights on the ionic exchange mechanisms between VOGNs and organic electrolytes, showing a major contribution of anions. A more advanced electrogravimetric methodology, ac-Electrogravimetry, was then used to access specific dynamic attributes for each species exchanged at the VOGN electrode surface. Accordingly, under the conditions of this study, anions were confirmed to be the major energy storage vector with high kinetic values and low transfer resistance while cations and free solvent molecules are given non-negligible supporting roles. Keywords: Supercapacitors, Microbalance, ac-Electrogravimetry, Graphen
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gravimetric and dynamic deconvolution of global eqcm response of carbon nanotube based electrodes by ac Electrogravimetry
Electrochemistry Communications, 2016Co-Authors: Freddy Escobarteran, H Perrot, J.v. Garcia, Y. Jiménez, Antonio Arnau, Ozlem SelAbstract:The capacitive charge storage of carbon nanotube (CNT) based electrodes was investigated by ac-Electrogravimetry which couples fast quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS). In contact with an aqueous NaCl electrolyte, evidence was found that there are two types of cations (Na + .H 2 O and H +) electroadsorbed with different kinetics for cathodic potentials and the Cl-ions for anodic potentials together with free water molecules. The reconstruction of the total mass response from independent ac-Electrogravimetry measurements agrees perfectly well with the global EQCM response. Our findings reveal the unique sensitivity of the ac-Electrogravimetry to provide a fair gravimetric and dynamic deconvolution of the global EQCM responses.
C Gabrielli - One of the best experts on this subject based on the ideXlab platform.
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influence of the incorporation of ceo2 nanoparticles on the ion exchange behavior of dodecylsulfate doped polypyrrole films ac Electrogravimetry investigations
Electrochimica Acta, 2014Co-Authors: Jerónimo Agrisuelas, C Gabrielli, Chabba Benmouhoub, N Benbrahim, Francoise Pillier, A Kadri, Alain PailleretAbstract:Cerium oxide (CeO2) nanoparticles (NPs) possessing defined size and crystallinity have been synthe-sised by a co-precipitation method. The effect of several parameters, such as the nature of the solventand the calcination process, on the crystallite size was studied by XRD, TEM and BET methods. TheseCeO2nanoparticles were then incorporated in dodecylsulfate (DS) doped PPy films during their elec-trodeposition in potentiodynamic conditions in order to produce PPy-DS/CeO2NPs nanocomposite thinfilms on gold coated quartz crystals. Simultaneous EQCM experiments revealed successful incorpora-tion of increasing amounts of cerium oxide nanoparticles in the polypyrrole matrix during each of theconsecutive CV scans. This was confirmed using FEG-SEM and EDS microanalysis.The ion exchange phenomena occurring in the resulting nanocomposite materials were studied byac-Electrogravimetry in NaCl aqueous electrolyte. PPy-DS films appear to be mainly cation exchang-ers, independently from the incorporation of CeO2nanoparticles (NPs), even though chloride anions insmaller amounts, and free water molecules, are simultaneously transferred at the film/electrolytic solu-tion interface. This study also reveals that the kinetics of Cl−ion insertion occurring at the film/electrolyteinterface upon oxidation is persistently slower in PPy-DS/CeO2NPs films than in PPy-DS films through-out the entire potential window of investigation. However, the relative concentration changes of Cl−ions in PPy-DS/CeO2NPs films is about two times greater than that occurring in pristine PPy-DS films.Such conclusion tends to demonstrate that CeO2NPs have the ability to modify the morphology of elec-trodeposited PPy-DS thin films as well as their subsequent permeability towards ions contained in theelectrolytic solution, possibly via the perturbation of polymer chain interactions and organisation.
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effects of anion size on the electrochemical behavior of h2so4 structured poly o toluidine films an ac Electrogravimetry study in acid solutions
Electrochimica Acta, 2014Co-Authors: J J Garciajareno, Jerónimo Agrisuelas, C Gabrielli, H Perrot, F. VicenteAbstract:Abstract ac-Electrogravimetry has allowed an easy separation of kinetic information to be evaluated for all the transferred species in three different H2SO4-structured poly(o-toluidine) or POT films, POT- N O 3 − , POT- C l O 4 − and POT-Cl− films when they are polarized between the pernigraniline (oxidized) and leucoemeraldine (reduced) forms. It is clear that larger anions slow down the electrochemical transitions of POT films, but the effects of anion transfer on hydrated protons and free solvent transfers are affected. For the same polymeric structure of a POT film, the kinetics of all specie transfers have been evaluated considering the size of species, geometric molecular structure, the interactions with the polymer structure of POT, the hydrophobicity of species transferred, the polymeric rearrangements and the oxidation state of the film. When the polymeric structure is not adapted to the anion in solution, the transfer of non-charged molecules has a mixed kinetic control depending on anion transfer and mechanical contractions/expansions of film. By taking into account all these considerations, the versatility of one type of sensor device could be improved and extended to different analytical situations.
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determination of the diffusion coefficient of protons in nafion thin films by ac Electrogravimetry
Langmuir, 2013Co-Authors: Ozlem Sel, C Gabrielli, Christel Labertyrobert, To Thi L. Kim, Catherine Debiemmechouvy, H PerrotAbstract:This letter deals with an adaptation of the ac-Electrogravimetry technique to extract separately the dynamic properties of H+ and water in Nafion nanometric thin films (average thickness of 400 nm)...
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frequency voltage conversion circuit for alternating current Electrogravimetry
Electronics Letters, 2013Co-Authors: D Vazquezuzal, C Gabrielli, H Perrot, L Rodriguezpardo, D Rose, Ozlem SelAbstract:A frequency/voltage conversion circuit for alternating current electrogravimetric measurements based on quartz crystal microbalance oscillators is proposed. This circuit improves the sensitivity and the bandwidth of the conversion systems proposed until now. Static and dynamic calibration results of the circuit are reported. These results prove its reliability for alternating current-electrogravimetric measurements and will allow the development of new applications in various electrochemical fields.
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electrogravimetric methods an attractive tool for investigating solid electrolytes for electrochemical conversion devices
223rd ECS Meeting (May 12-17 2013), 2013Co-Authors: Ozlem Sel, C Gabrielli, Christel Labertyrobert, H PerrotAbstract:The need for new solid electrolytes with improved ion-conducting properties continues to be one of the main pressing concerns in fuel cell research. In accompanying this search for optimal materials, appropriate characterization tools to assess key parameters of newly developed solid electrolytes are required. This tutorial paper will focus on electrochemical impedance spectroscopy (EIS), which has been established as a powerful technique in the characterization of electrochemical conversion devices such as fuel cells. Further attention will focus on coupling EIS with gravimetric methods (fast quartz crystal microbalance (QCM)) under dynamic regime. This coupling, so called ac-Electrogravimetry measures the usual electrochemical impedance, ΔE/ΔI (ω), and the mass/potential transfer function, Δm/ΔE (ω), simultaneously. The main interests of this coupling are its ability to indicate the contribution of the charged and uncharged species and to separate the anionic, cationic, and free solvent contributions during the electrochemical/chemical processes. These features make the ac-Electrogravimetry an attractive and appropriate tool to investigate transfer/transport phenomena of charged and uncharged species in ion-conducting membranes/electrolytes. As a pertinent example, the adaptation of acElectrogravimetry to evaluate the H diffusion and insertion in polymer electrolyte membranes (PEMs) will be discussed. The species that are essentially not easy to detect gravimetrically, such as protons, could be studied due to the high precision and sensitivity of these coupled techniques. To perform such experiments, an electroactive film mediator has to be inserted between the working electrode of the microbalance and the proton conducting membrane. This mixed conductor mediator is necessary to provide transfer of protons between the different interfaces and therefore, to study the proton transport inside PEMs which are only ionic conductors. The results of a new class of hybrid membranes (HMs) based on a fluorinated polymer associated with mesostructured silica (Fig. 1) will be compared to model materials such as perfluorosulfonic acid based membranes (PFSA). An original theoretical approach will be discussed for extracting the key parameters (such as concentration change of the exchanged species and the diffusion coefficient of the protons in PEMs) from coupled EIS and QCM data. The characterization of new membranes with these novel techniques can explain the ion conduction behavior and can determine whether the limiting mechanism, if there is any, is the proton insertion or diffusion. By evaluating the potential of these new materials via coupled EIS methods, specific materials can be effectively and quickly chosen based on their properties. 0 20 40 60 80 100 0 20 40 60 80 100 a
F. Vicente - One of the best experts on this subject based on the ideXlab platform.
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alternating current Electrogravimetry of copper electrodissolution in a sulfuric acid solution
Electrochimica Acta, 2017Co-Authors: Alejandro Cuenca, J J Garciajareno, Jerónimo Agrisuelas, F. VicenteAbstract:Abstract Copper electrodissolution processes have been studied by means of electrochemical impedance spectroscopy and ac-Electrogravimetry (mass impedance). During ac-Electrogravimetry acquisition, mass decreases or increases due to the electrodissolution or the electrodeposition of copper, respectively. As a result, this continuous mass drift makes impossible obtaining a true ac-Electrogravimetry response unless a numerical correction was applied. It has been compared the electrochemical behavior of copper layers previously treated and other freshly deposited on the gold electrode of the quartz crystal microbalance. The simultaneous analysis of both impedance functions has allowed separating between contributions to the current response (electrochemical impedance spectroscopy) and contributions to the mass on the electrode surface (corrected ac-Electrogravimetry). It has been possible obtaining information about the relative rate of transport of charged species at different potentials for both, Cu and Cu/layer electrodes. The dependence of the mass dissolution rate on the applied potential suggests that the Cu(I) intermediate species play no important role in these experimental conditions. It has been measured both, the open circuit potential at which current equals to zero and the potential at which the change of mass on the electrode equals to zero.
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evaluation of the electrochemical anion recognition of no3 imprinted poly azure a in no3 cl mixed solutions by ac Electrogravimetry
Electrochimica Acta, 2016Co-Authors: Jerónimo Agrisuelas, Roger Sanchisgual, J J Garciajareno, Claude Gabrielli, Hubert Perrot, F. VicenteAbstract:Abstract During the reversible electrochemical reactions of the intrinsically conducting polymer (ICP) films, ions are inserted in them to balance the inner charge site of the polymer. For this reason, doped ICP films with anions or cations can be good candidates for the electrochemical removal of contaminant ions from wastewater. In this work, a polymer of a phenothiazine derivative (poly(Azure A or PAA)) was electrosynthesized by cyclic voltammetry in aqueous solutions using nitrate ions as a structural template. After that, PAA film was repeatedly cycled in identical conditions in a monomer-free solution. The electrochemical anion recognition of the nitrate-imprinted poly(Azure A) ( N O 3 − − PAA ) was evaluated by the combination of electrochemical and mass impedance spectroscopy, the so called ac-Electrogravimetry method. Ac-Electrogravimetry allows the selectivity of N O 3 − − PAA to be quantified. N O 3 − − PAA exhibited a special sensitivity and selectivity for the nitrate ions over the interfering chloride ions in mixed N O 3 − and Cl − containing solutions. The Dixon plots of the kinetic constants obtained by ac-Electrogravimetry were used as a graphical method to reveal that N O 3 − and Cl − transfers are non-competitive at lower doped states of the polymer but competitive at higher doped states. The reversibility of nitrate incorporation controlled by an external potential modulation, the relative low cost and easy synthesis render the N O 3 − − PAA film suitable in practical implications such as nitrate scavenger in aqueous contaminated environments.
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electrochemistry and electrocatalysis of a pt poly neutral red hybrid nanocomposite
Electrochimica Acta, 2015Co-Authors: Jerónimo Agrisuelas, J J Garciajareno, P Rivas, J M Rodriguezmellado, F. VicenteAbstract:Abstract Platinum nanoparticles have been deposited on a scaffold of electrosynthetized phenazine-type polymer, the poly(neutral red). This work discusses the role of poly(neutral red) in the electrochemistry and electrocatalysis properties of the hybrid nanocomposite. In situ combination of electrochemical quartz crystal microbalance and visible-near infrared spectroscopy (cyclic Vis-NIR spectroElectrogravimetry) and a combination of electrochemical impedance spectroscopy and mass impedance spectroscopy ( ac -Electrogravimetry) were employed. Two electrochemical processes have been identified in our experimental conditions. On the one hand, the radical cations (polarons) localized in the inter-monomer bonds of poly(neutral red) are identities stabilized by platinum nanoparticles. The polaron charge is balanced by the relative slow transfer of anions between the hybrid nanocomposite and solution. On the other hand, a relative fast transfer of cation (but not H 3 O + ) is involved in the second electrochemical process. H 2 O 2 was used as the target analyteto study the electrocatalytic reaction. The hybrid nanocomposite catalyzes the H 2 O 2 reduction in phosphate buffer solutions at neutral pH . Polarons have been identified as the electrocatalytic sites. Poly(neutral red) would act as a proton reservoir used during the H 2 O 2 reduction. The excellent electrocatalytic response and the knowledge of its electrochemical mechanism can help to developbiosensors for other analytes which react with radical species.
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Polymer dynamics in thin p-type conducting films investigated by ac-Electrogravimetry. Kinetics aspects on anion exclusion, free solvent transfer, and conformational changes in poly(o-toluidine)
Electrochimica Acta, 2015Co-Authors: Jerónimo Agrisuelas, Claude Gabrielli, Hubert Perrot, Ozlem Sel, J.j. García-jareño, F. VicenteAbstract:A new transfer model is proposed to explain ac-Electrogravimetry response of p-doped films. This model takes into account the exclusion effect occurring as a result of the anion transfer. The insertion/expulsion of anions inside a film involves simultaneously the expulsion/insertion of free solvent molecules. The number of solvent molecules excluded depends on the volume of anion transferred. Solvent transfer stimulated by the conformational changes of films constitutes the remaining electrogravimetric response when the exclusion process cannot explain by itself this response. Consequently, the kinetics of this free solvent transfer can be directly related to the kinetics of conformational changes. This model was validated in poly(o-toluidine) thin films where electrochemical kinetics were quantitatively investigated as a function of the applied potential. As far as we know, for the first time, charge transfer and conformational changes could be kinetically separated. This new transfer model may respond to fundamental questions on the electrochemistry of conducting polymers, which may have a significant impact on a large number of applications.
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correction of mass drift in ac Electrogravimetry of prussian yellow films mass impedance under apparently non steady state condition
Electrochimica Acta, 2014Co-Authors: Jerónimo Agrisuelas, J J Garciajareno, C Moreno, F. VicenteAbstract:Abstract Mass impedance spectroscopy allows the modulated response of mass of a resonant electrode to be followed at different perturbation frequencies during electrochemical impedance spectroscopy experiments (ac-Electrogravimetry). However, some difficulties appear if a continuous mass change takes place foreign to the mass changes due to the ac-modulated electrochemical processes. A new strategy is proposed to solve this limitation. Both, mass and potential analog signals are recorded frequency by frequency from 100 Hz up to the lowest frequencies. Then, a numerical procedure based on a multiparametric fitting of raw data against the elapsed time allows the contribution due to the modulated ac-potential perturbation to be separated from other contributions. Thus, a true impedance value is obtained. This procedure is tested and validated for electrochemical impedance spectroscopy of Prussian Blue films at potentials where no continuous electric current change has been detected. The same procedure was applied to the study of mass impedance of Prussian Yellow films where in some experimental conditions mass continuously decreases. Valuable information about the role of potassium cation and nitrate anion in the electrochemistry of this film was obtained. This procedure also opens a new way to obtain reliable kinetic interpretations in other similar cases such as electrochemical dissolution and deposition of metals as well as electrochemical polymerization or formation and dissolution of passive layers.
Hubert Perrot - One of the best experts on this subject based on the ideXlab platform.
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making advanced Electrogravimetry as an affordable analytical tool for battery interface characterization
Analytical Chemistry, 2020Co-Authors: Hubert Perrot, Ozlem Sel, Pierre Lemaire, Thomas Dargon, Daniel Alves Dalla Corte, Jeanmarie TarasconAbstract:Numerous sophisticated diagnostic techniques have been designed to monitor electrode-electrolyte interfaces that mainly govern the lifetime and reliability of batteries. Among them is the electrochemical quartz crystal microbalance (EQCM) that offers valuable insights of the interfaces once the required conditions of the deposited film in terms of viscoelastic and hydrodynamic properties are fulfilled. Herein, we propose a friendly protocol that includes the elaboration of a homogeneous deposit by spray coating followed by QCM measurements at multiharmonic frequencies to ensure the film flatness and rigidity for collecting meaningful data. Moreover, for easiness of the measurements, we report the design of a versatile and airtight EQCM cell setup that can be used either with aqueous or non-aqueous electrolytes. We also present, using a model battery material, LiFePO4, how dual frequency and motional resistance monitoring during electrochemical cycling can be used as a well-suitable indicator for achieving reliable and reproducible electrogravimetric measurements. We demonstrate through this study the essential role of the solvent assisting lithium-ion insertion at the LiFePO4 interface with a major outcome of solvent-dependent interfacial behavior. Namely, in aqueous media, we prove a near-surface desolvation of lithium ions from their water solvation shell as compared with organic molecules. This spatial dissimilarity leads to a smoother Li-ion transport across the LFP-H2O interface, hence accounting for the difference in rate capability of LFP in the respective electrolytes. Overall, we hope our analytical insights on interfacial mechanisms will help in gaining a wider acceptance of EQCM-based methods from the battery community.
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Charge Storage Properties of Nanostructured Poly (3,4–ethylenedioxythiophene) Electrodes Revealed by Advanced Electrogravimetry
Nanomaterials, 2019Co-Authors: D. Aradilla, Hubert Perrot, G. Bidan, F. Billon, Catherine Debiemme, Ozlem SelAbstract:PEDOT nanowires (NWs) directly grown on the conducting electrode of quartz resonators enable an advanced electrogravimetric analysis of their charge storage behavior. Electrochemical quartz crystal microbalance (EQCM) and its coupling with electrochemical impedance spectroscopy (ac-Electrogravimetry or AC-EG) were used complementarily and reveal that TBA + , BF 4 − and ACN participate in the charge compensation process with different kinetics and quantity. BF 4 − anions were dominant in terms of concentration over TBA + cations and the anion transfer results in the exclusion of the solvent molecules. TBA + concentration variation in the electrode was small compared to that of the BF 4 − counterpart. However, M w of TBA + is much higher than BF 4 − (242.3 vs. 86.6 g·mol −1). Thus, TBA + cations' gravimetric contribution to the EQCM response was more significant than that of BF 4 −. Additional contribution of ACN with an opposite flux direction compared with BF 4 − , led to a net mass gain/lost during a negative/positive potential scan, masking partially the anion response. Such subtleties of the interfacial ion transfer processes were disentangled due to the complementarity of the EQCM and AC-EG methodologies, which were applied here for the characterization of electrochemical processes at the PEDOT NW electrode/organic electrolyte interface.
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ion dynamics at the single wall carbon nanotube based composite electrode electrolyte interface influence of the cation size and electrolyte ph
Journal of Physical Chemistry C, 2019Co-Authors: Freddy Escobarteran, Hubert Perrot, Ozlem SelAbstract:Electrochemical quartz crystal microbalance and ac-Electrogravimetry methods were employed to study ion dynamics in single wall carbon nanotube (SWCNT) based electrodes in various aqueous electrolytes and different electrolyte pH values. The pH dependence of the electroadsorption phenomena studied in NaCl at pH 2, pH 7, and pH 10 indicated that low and high pH values amplify the anion and cation contribution, respectively, which means that in the same potential range, the pH of the aqueous electrolyte is adjustable to preferentially electroadsorb cations or anions. The cation size dependence of the electrodeposition phenomena was also studied by changing the electrolyte cation from Li+, Na+ to K+. The results indicated that Li+ and Na+ species are more tightly bonded to their water molecules in their hydration shell compared to the potassium species; i.e., dehydration of K+ is easier than that of Na+ and Li+. K+ ions due their completely dehydrated state probably become equivalent to partially dehydrated ...
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Tuning Charge Storage Properties of Supercapacitive Electrodes Evidenced by In Situ Gravimetric and Viscoelastic Explorations
2019Co-Authors: Wanli Gao, Hubert Perrot, Catherine Debiemme-chouvy, Mohammed Lahcini, Ozlem SelAbstract:Revealed by an integrated electrogravimetric and viscoelastic method, slightly electrochemically reduced graphene oxide (ERGO) presents an anion preference for charge storage and delivery, while with the progressive removal of oxygen functionalities on its basal planes, cations begin to predominate in charge compensation. This “anion-to-cation” evolution in neutral aqueous media can not only affect the electrochemical charge storage, but also play an important role in electrode’s viscoelasticity. It was demonstrated that oxygen functionalities could modify the interactions between graphene layers and even contribute to pseudocapacitances. However, the role of oxygen functionalities in species transfer and viscoelastic variations still remains poorly understood. Herein, a combined methodology of electrochemical quartz crystal microbalance (EQCM), ac-Electrogravimetry and electroacoustic impedance measurements was proposed for characterizing the electrochemical and viscoelastic responses of graphene oxides with various degree of electrochemical reduction. With the removal of oxygen containing functional groups, ERGO electrode exhibits (i) a gradually enhanced specific capacitance (Cs) with increased flexibility (decreased storage moduli, G′); (ii) a dehydration process of cations (i.e., from Na+·2H2O to Na+·H2O); and (iii) a potential-dependent “stiffened-softened” behavior. These results open the door for a suitable design of GO-based materials for electrochemical energy storage and shed light on electronic devices where ion-selective behavior plays a key role
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Unveiling the ionic exchange mechanisms in vertically-oriented graphene nanosheet supercapacitor electrodes with electrochemical quartz crystal microbalance and ac -Electrogravimetry
Electrochemistry Communications, 2018Co-Authors: D. Aradilla, Hubert Perrot, G. Bidan, F. Billon, M. Delaunay, J.m. Gérard, Ozlem SelAbstract:This work presents the first electrochemical quartz crystal microbalance (EQCM) results for vertically-oriented graphene nanosheets (VOGNs) as supercapacitor electrodes. Conventional EQCM technique delivered primary insights on the ionic exchange mechanisms between VOGNs and organic electrolytes, showing a major contribution of anions. A more advanced electrogravimetric methodology, ac-Electrogravimetry, was then used to access specific dynamic attributes for each species exchanged at the VOGN electrode surface. Accordingly, under the conditions of this study, anions were confirmed to be the major energy storage vector with high kinetic values and low transfer resistance while cations and free solvent molecules are given non-negligible supporting roles.
Ozlem Sel - One of the best experts on this subject based on the ideXlab platform.
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scrutiny of the licoo2 composite electrode electrolyte interface by advanced Electrogravimetry and implications for aqueous li ion batteries
Journal of Physical Chemistry C, 2021Co-Authors: Wanli Gao, H Perrot, Christel Labertyrobert, Natacha Krins, Ozlem SelAbstract:The recent tendency in the battery field toward the use of aqueous electrolytes stimulated several studies searching for compatible electrode materials and charge carriers. Still, another aspect to...
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making advanced Electrogravimetry as an affordable analytical tool for battery interface characterization
Analytical Chemistry, 2020Co-Authors: Hubert Perrot, Ozlem Sel, Pierre Lemaire, Thomas Dargon, Daniel Alves Dalla Corte, Jeanmarie TarasconAbstract:Numerous sophisticated diagnostic techniques have been designed to monitor electrode-electrolyte interfaces that mainly govern the lifetime and reliability of batteries. Among them is the electrochemical quartz crystal microbalance (EQCM) that offers valuable insights of the interfaces once the required conditions of the deposited film in terms of viscoelastic and hydrodynamic properties are fulfilled. Herein, we propose a friendly protocol that includes the elaboration of a homogeneous deposit by spray coating followed by QCM measurements at multiharmonic frequencies to ensure the film flatness and rigidity for collecting meaningful data. Moreover, for easiness of the measurements, we report the design of a versatile and airtight EQCM cell setup that can be used either with aqueous or non-aqueous electrolytes. We also present, using a model battery material, LiFePO4, how dual frequency and motional resistance monitoring during electrochemical cycling can be used as a well-suitable indicator for achieving reliable and reproducible electrogravimetric measurements. We demonstrate through this study the essential role of the solvent assisting lithium-ion insertion at the LiFePO4 interface with a major outcome of solvent-dependent interfacial behavior. Namely, in aqueous media, we prove a near-surface desolvation of lithium ions from their water solvation shell as compared with organic molecules. This spatial dissimilarity leads to a smoother Li-ion transport across the LFP-H2O interface, hence accounting for the difference in rate capability of LFP in the respective electrolytes. Overall, we hope our analytical insights on interfacial mechanisms will help in gaining a wider acceptance of EQCM-based methods from the battery community.
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elucidating the origin of the electrochemical capacity in a proton based battery hxiro4 via advanced Electrogravimetry
ACS Applied Materials & Interfaces, 2020Co-Authors: Ozlem Sel, H Perrot, Pierre Lemaire, Daniel Alves Dalla Corte, Jeanmarie Tarascon, Antonella IadecolaAbstract:Recently, because of sustainability issues dictated by societal demands, more importance has been given to aqueous systems and especially to proton-based batteries. However, the mechanisms behind t...
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Charge Storage Properties of Nanostructured Poly (3,4–ethylenedioxythiophene) Electrodes Revealed by Advanced Electrogravimetry
Nanomaterials, 2019Co-Authors: D. Aradilla, Hubert Perrot, G. Bidan, F. Billon, Catherine Debiemme, Ozlem SelAbstract:PEDOT nanowires (NWs) directly grown on the conducting electrode of quartz resonators enable an advanced electrogravimetric analysis of their charge storage behavior. Electrochemical quartz crystal microbalance (EQCM) and its coupling with electrochemical impedance spectroscopy (ac-Electrogravimetry or AC-EG) were used complementarily and reveal that TBA + , BF 4 − and ACN participate in the charge compensation process with different kinetics and quantity. BF 4 − anions were dominant in terms of concentration over TBA + cations and the anion transfer results in the exclusion of the solvent molecules. TBA + concentration variation in the electrode was small compared to that of the BF 4 − counterpart. However, M w of TBA + is much higher than BF 4 − (242.3 vs. 86.6 g·mol −1). Thus, TBA + cations' gravimetric contribution to the EQCM response was more significant than that of BF 4 −. Additional contribution of ACN with an opposite flux direction compared with BF 4 − , led to a net mass gain/lost during a negative/positive potential scan, masking partially the anion response. Such subtleties of the interfacial ion transfer processes were disentangled due to the complementarity of the EQCM and AC-EG methodologies, which were applied here for the characterization of electrochemical processes at the PEDOT NW electrode/organic electrolyte interface.
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ion dynamics at the single wall carbon nanotube based composite electrode electrolyte interface influence of the cation size and electrolyte ph
Journal of Physical Chemistry C, 2019Co-Authors: Freddy Escobarteran, Hubert Perrot, Ozlem SelAbstract:Electrochemical quartz crystal microbalance and ac-Electrogravimetry methods were employed to study ion dynamics in single wall carbon nanotube (SWCNT) based electrodes in various aqueous electrolytes and different electrolyte pH values. The pH dependence of the electroadsorption phenomena studied in NaCl at pH 2, pH 7, and pH 10 indicated that low and high pH values amplify the anion and cation contribution, respectively, which means that in the same potential range, the pH of the aqueous electrolyte is adjustable to preferentially electroadsorb cations or anions. The cation size dependence of the electrodeposition phenomena was also studied by changing the electrolyte cation from Li+, Na+ to K+. The results indicated that Li+ and Na+ species are more tightly bonded to their water molecules in their hydration shell compared to the potassium species; i.e., dehydration of K+ is easier than that of Na+ and Li+. K+ ions due their completely dehydrated state probably become equivalent to partially dehydrated ...