Tag Archive for: electrode/electrolyte interface

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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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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