Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices.

https://hal.archives-ouvertes.fr/hal-02417326/document

Materials for electrochemical capacitors

In this critical review, metal oxides-based materials for electrochemical supercapacitor (ES) electrodes are reviewed in detail together with a brief review of carbon materials and conducting polymers. Their advantages, disadvantages, and performance in ES electrodes are discussed through extensive analysis of the literature, and new trends in material development are also reviewed. Two important future research directions are indicated and summarized, based on results published in the literature: the development of composite and nanostructured ES materials to overcome the major challenge posed by the low energy density of ES (476 references).

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A review of electrode materials for electrochemical supercapacitors

The surface area of a single graphene sheet is 2630 m2/g, substantially higher than values derived from BET surface area measurements of activated carbons used in current electrochemical double layer capacitors. Our group has pioneered a new carbon material that we call chemically modified graphene (CMG). CMG materials are made from 1-atom thick sheets of carbon, functionalized as needed, and here we demonstrate in an ultracapacitor cell their performance. Specific capacitances of 135 and 99 F/g in aqueous and organic electrolytes, respectively, have been measured. In addition, high electrical conductivity gives these materials consistently good performance over a wide range of voltage scan rates. These encouraging results illustrate the exciting potential for high performance, electrical energy storage devices based on this new class of carbon material.

Graphene-Based Ultracapacitors

The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties * To whom correspondence should be addressed. Phone, 404-8940292; fax, 404-894-0294; e-mail, mostafa.el-sayed@ chemistry.gatech.edu. † Case Western Reserve UniversitysMillis 2258. ‡ Phone, 216-368-5918; fax, 216-368-3006; e-mail, burda@case.edu. § Georgia Institute of Technology. 1025 Chem. Rev. 2005, 105, 1025−1102

Chemistry and properties of nanocrystals of different shapes.

This tutorial review provides a brief summary of recent research progress on carbon-based electrode materials for supercapacitors, as well as the importance of electrolytes in the development of supercapacitor technology. The basic principles of supercapacitors, the characteristics and performances of various nanostructured carbon-based electrode materials are discussed. Aqueous and non-aqueous electrolyte solutions used in supercapacitors are compared. The trend on future development of high-power and high-energy supercapacitors is analyzed.

Carbon-based materials as supercapacitor electrodes

LaCo(fsa) 2 en-Montmorillonite and LaCo(fsa) 2 en-Taeniolite ((fsa) 2 en = N,N'-bis(3-carboxysalicydene)ethylenediamine) derivatives have been synthesized by cationic exchange and characterized. The thermal treatment of the exchanged clays under oxidizing atmosphere led to the formation of nanocomposites above about 300°C. It has been shown that the LaCoO y -Montmorillonite nanocomposite is stable up to about 550°C versus 700°C for the LaCoO y -Taeniolite nanocomposite. Both are constituted of oxide pillars (diameter 20-40A) intercalated within the silicate matrix.

A Comparative Study of Silicate-Oxide Nanocomposites

Process for the opening of carbon nanotubes to remove impurities comprise a liquid phase oxidation stage followed by a gaseous phase oxidation. An Independent claim is also included for the use of the nanotubes obtained.

Process for the opening of the extremities of carbon nanotubes obtained by catalytic preparation by two stages of liquid and gaseous phase oxidation

BxC1−x (x = 0.1 and 0.25) oriented platelets were intercalated with alkali metal vapor (M = K, Rb, Cs), giving first-stage M(B0.1C0.9)8 and M(B0.25C0.75)10. The presence of M(BxC1−x)5 dense domains interstratified in the first-stage structure were brought out from the 00.l simulations. The presence of these domains is attributed to the acceptor electron effect of boron, which slightly enhances the intercalation rate as compared to pure carbon. Intercalation of Cs in liquid ammonia is improved using 1600 °C heat-treated B0.25C0.75 as a host material, and the composition Cs(B0.25C0.75)12 is reached after intercalation. In intercalation compounds of Cs in liquid ammonia obtained from heat-treated B0.25C0.75, as the heat-treatment temperature (HTT) was increased from 1600 to 2000 °C, the segregation of first stage was observed in two structures Cs(BxC1−x)8 and Cs(BxC1−x)10 with the respective 2 × 2 0° and 2.23 × 2.23 two-dimensional lattices of the cesium atoms. The presence of these two structures is assigned to the heterogeneity of the host material induced by the formation of B4C boron carbide domains and the consecutive boron elimination of the BxC1−x lamellar phase with increasing HTT.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0884291400055448

Synthesis and Structure of BxC1−x Intercalation Compounds with Heavy Alkali Metals (K, Rb, and Cs)

Graphite Insertion Compounds as Precursors of Highly Dispersed Metals. Part 1. Coupling of Benzylic Halides.

Procede cyclique d'adsorption reversible de polluants emergents ou de micropolluants pour la depollution d'un milieu aqueux contamine par lesdits polluants emergents ou lesdits micropolluants, ledit procede etant realise sans apport de gaz contenant de l'oxygene, sans apport d'initiateurs de radicaux, et comprenant une pluralite de cycles, chaque cycle comprenant les etapes suivantes : a. l'adsorption desdits polluants emergents et micropolluants contenus dans ledit milieu aqueux sur une electrode en feutre de carbone active par mise en contact dudit milieu aqueux contamine avec ladite electrode de feutre de carbone active permettant d'adsorber lesdits polluants emergents et micropolluants contenus dans ledit milieu aqueux sur ladite electrode en feutre de carbone active, et b. la regeneration in situ de ladite electrode en feutre de carbone active par polarisation negative permettant la desorption electrochimique desdits polluants emergents et micropolluants adsorbes a l'etape a) et la reutilisation de ladite electrode en feutre de carbone active dans le cycle suivant. et son utilisation pour la depollution de milieux aqueux.

François Béguin

Papers

A Comparative Study of Silicate-Oxide Nanocomposites

Process for the opening of the extremities of carbon nanotubes obtained by catalytic preparation by two stages of liquid and gaseous phase oxidation

Synthesis and Structure of BxC1−x Intercalation Compounds with Heavy Alkali Metals (K, Rb, and Cs)

Graphite Insertion Compounds as Precursors of Highly Dispersed Metals. Part 1. Coupling of Benzylic Halides.

Piegeage reversible sur carbone actif