Tag Archive for: Keyhole 9 MHz QCM

Publication on AWSensors technology

Highly Ordered Graphene Polydopamine Composite Allowing Fast Motion of Cations: Toward a High-Performance Microsupercapacitor

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Authors: Adnane Bouzina, René Meng, Cyrille Bazin, Hubert Perrot, Ozlem Sel, Catherine Debiemme-Chouvy

Journal: Adv. Mater. Interfaces (2023)

 

Abstract

The simple and eco-friendly preparation of microsupercapacitor remains a great challenge. Here are presented the preparation and the characterizations of an all-solid symmetric micro-supercapacitor based on a new composite formed of highly ordered graphene sheets due to the presence of polydopamine between the layers, which present a d-spacing of 0.356 nm. This graphene-polydopamine composite is prepared by electroreduction of graphene oxide (GO) followed by the electrooxidation of dopamine added into the initial solution, i.e., after GO reduction. In Na2SO4 solution, this composite material shows excellent capacitance and stability even at a high scan rate (2 V s−1) and a very low relaxation time (τ0) of 62 ms. This value is in very good agreement with the high transfer kinetic and low transfer resistance values of the ions implied in the charge storage process (Na+·2H2O and Na+) determined by ac-electrogravimetry. Finally, it is shown that the all-solid micro-supercapacitor (interdigitated electrodes obtained using a CO2 laser and Na2SO4/PVA hydrogel) prepared with this new composite delivers a remarkable energy density of 6.36 mWh cm−3 for a power density of 0.22 W cm−3 and exhibits excellent cycling stability (98% of retention after 10 000 cycles at 2 V s−1).

 

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Publication on AWSensors technology

Interface Properties of 2D Graphene–Polydopamine Composite Electrodes in Protic Ionic Liquid-Based Electrolytes Explored by Advanced Electrogravimetry

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Authors: Adnane Bouzina, Hubert Perrot, Catherine Debiemme-Chouvy, and Ozlem Sel

Journal: ACS Appl. Energy Mater. (2022)

 

Abstract

A fundamental understanding of the processes occurring at the electrode/electrolyte interfaces is of paramount importance to enhance the performance of energy storage devices. Addressing this issue requires suitable characterization tools, due to the complex nature of such interfaces. By means of electrochemical quartz crystal microbalance (EQCM) and its advanced mode, the so-called ac-electrogravimetry, herein, we report on the interfacial properties of two-dimensional (2D) graphene–polydopamine (ERGO-PDA) composite electrodes in diverse electrolyte compositions including a protic ionic liquid (PIL), pyrrolidinium hydrogen sulfate [Pyr+][HSO4–]. We have performed a comparative study in a [Pyr+][HSO4–]–water binary mixture in the absence and presence of Na2SO4 and compared it with the interfacial behavior of ERGO-PDA in a 0.5 M Na2SO4 (pH = 2) pristine electrolyte. Our EQCM and ac-electrogravimetric analyses reveal that the [Pyr+] ions, due to their chaotropic nature, inhibit the approach of kosmotropic Na+ ions and water molecules to the interface, suppressing the contribution of electrodragged water molecules, substantially observed in the case of pristine aqueous electrolyte. Despite the dissimilarity of the charge compensation process occurring in the presence of [Pyr+][HSO4–], the ERGO-PDA electrode is able to maintain similar cycling stability (99% for 10,000 cycles at 1000 mV·s–1) and specific capacitance values (325 F·cm–3) compared with the pristine aqueous electrolyte, with the advantage of superior energy density (16.3 versus 8.7 mWh·cm–3) due to a noticeably enlarged potential window in [Pyr+][HSO4–]–water binary mixtures.

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Publication on AWSensors technology

Interfacial charge storage mechanisms of composite electrodes based on poly(ortho-phenylenediamine)/carbon nanotubes via advanced electrogravimetry

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Authors: El Mahdi Halim, Rezan Demir-Cakan, Hubert Perrot, Mama El Rhazi, Ozlem Sel

Journal: The Journal of Chemical Physics (2022)

 

Abstract

To reach a deeper understanding of the charge storage mechanisms of electrode materials is one of the challenges toward improving their energy storage performance. Herein, we investigate the interfacial ion exchange of a composite electrode made of carbon nanotube/poly( ortho-phenylenediamine) (CNT/P oPD) in a 1M NaCl aqueous electrolyte via advanced electrogravimetric analyses based on electrochemical quartz crystal microbalance (EQCM). Classical EQCM at different scan rates of the potential revealed the complex electrogravimetric behavior likely due to multi-species participation at different temporal scales. Thereafter, in order to better understand the behavior of each species (ions, counter ions, and co-ions) in the charge compensation mechanism, the electrogravimetric impedance spectroscopy analysis (also called ac-electrogravimetry) was pursued. Ac-electrogravimetry revealed the role of each species where Na + cations and Cl − anions as well as protons participate in the charge compensation mechanism of the CNT/P oPD composite with different kinetics and proportions. The water molecules with opposite flux direction with the cations are also detected, suggesting their exclusion during cationic species transfer. Having analyzed ac-electrogravimetry responses in depth, the synergistic interaction between the CNT and P oPD is highlighted, revealing the improved accessibility of species to new sites in the composite.

 

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Scientific publication

Interface evolution and performance degradation in LiCoO2 composite battery electrodes monitored by advanced EQCM

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Authors: Wanli Gao, Christel Laberty-Robert, Natacha Krins, Catherine Debiemme-Chouvya, Hubert Perrot and Ozlem Sel.
Journal: Electrochimica Acta (2022)

 

Abstract

Unravelling the underlying reasons for degradation mechanism of battery materials is of great fundamental and practical importance. For a classical electrode consisting of an active material, a conductive additive, and a polymeric binder, its capacity fading is commonly related with (i) mechanical degradation of polymeric binder and/or (ii) structural and compositional degradation of active materials. The former is more relevant for electrodes showing volume expansion and represented by the progressive breakage of polymeric binder network during battery operation, leading to the dissolution of the other two components into electrolytes. The latter is generally reflected by an irreversible phase transition in active materials, which may affect the species exchanged at the electrode/electrolyte interface and their interfacial transfer dynamics. By employing a coupled methodology pairing electrochemical techniques with piezoelectric probes derived from quartz crystal microbalance (QCM), this work reports on the evolution of the interfacial processes during electrochemical cycling and correlates to the performance degradation of the electrodes. Shown on a LiCoO2 (LCO) composite electrode as a model system, it was revealed that bare Li+ without a hydration sheath plays a dominant role in charge balance irrespective of the aging degree of the electrode under the experimental conditions of this work. However, Li+ transfer is closely accompanied with free H2O molecules with a Li+:H2O ratio around 10:1 at a polarization state close to LCO redox potential (0.65 V vs. Ag/AgCl). This ratio persists in all cycled electrodes with gradually faded interfacial transfer kinetics of Li+ and H2O along cycling. Such a fading in species interfacial transfer kinetics driven by the surficial evolution from LiCoO2 to CoO plays a major role in the electrode performance degradation during cycling.

LiCoO2 composite battery electrodes

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Scientific publication

Ion Dynamics at the Carbon Electrode/Electrolyte Interface: Influence of Carbon Nanotubes Types

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Authors: Freddy Escobar-Teran, Hubert Perrot and Ozlem Sel.
Journal: Materials (2022)

 

Abstract

Electrochemical quartz crystal microbalance (EQCM) and AC-electrogravimetry methods were employed to study ion dynamics in carbon nanotube base electrodes in NaCl aqueous electrolyte. Two types of carbon nanotubes, Double Wall Carbon Nanotube (DWCNT) and Multi Wall Carbon Nanotube (MWCNT), were chosen due to their variable morphology of pores and structure properties. The effect of pore morphology/structure on the capacitive charge storage mechanisms demonstrated that DWCNT base electrodes are the best candidates for energy storage applications in terms of current variation and specific surface area. Furthermore, the mass change obtained via EQCM showed that DWCNT films is 1.5 times greater than MWCNT films in the same potential range. In this way, the permselectivity of DWCNT films showed cation exchange preference at cathode potentials while MWCNT films showed anion exchange preference at anode potentials. The relative concentration obtained from AC-electrogravimetry confirm that DWCNT base electrodes are the best candidates for charge storage capacity electrodes, since they can accommodate higher concentration of charged species than MWCNT base electrodes.

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Publication on AWSensors technology

Correlation between the interfacial ion dynamics and charge storage properties of poly(ortho-phenylenediamine) electrodes exhibiting high cycling stability

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Authors: El Mahdi Halim, Rezan Demir-Cakan, Hubert Perrot, Mama El Rhazi, Ozlem Sel

Journal: The Journal of Power Sources (2019)

 

Abstract

An integrated electrogravimetric study based on electrochemical quartz crystal microbalance (EQCM) unravels the interfacial ion transfer phenomena of the poly(ortho-phenylenediamine) (PoPD) thin film electrodes. Through a methodology coupling QCM with electrochemical impedance spectroscopy (ac-electrogravimetry), our work indicates that charge compensation process of PoPD in aqueous electrolytes (in acidified NaCl) occurs with the participation of multiple species, each playing a role at different temporal scales. The PoPD films are tested in a 2 electrode Swagelok cell in which Zn is used as both reference and counter electrodes and exhibit excellent stability over 8000 cycles with a relatively high specific capacitance of about 110 F g−1 at 30 C (0.63 mA cm−2) current density. The high rate capability and the excellent cycling stability of the PoPD electrodes are correlated to the electrolyte composition and the significant role of H+ to the charge compensation process is unravelled, which is made possible with coupled electrogravimetric methods of our study. By determining the interfacial flux dynamics and as well as the relative proportions of species transferred at the electrode/electrolyte interface, our results contribute to the understanding of the charge-discharge process of PoPD polymer, yet underexplored but emerging as a pseudo-capacitive electrode material.

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