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

4.3. Reaction Mechanism 2373 4.4. Asymmetric Synthesis 2374 4.5. Outlook 2374 5. Alternating Polymerization of Oxiranes and CO2 2374 5.1. Reaction Outlines 2374 5.2. Catalyst 2376 5.3. Asymmetric Polymerization 2377 5.4. Immobilized Catalysts 2377 6. Synthesis of Urea and Urethane Derivatives 2378 7. Synthesis of Carboxylic Acid 2379 8. Synthesis of Esters and Lactones 2380 9. Synthesis of Isocyanates 2382 10. Hydrogenation and Hydroformylation, and Alcohol Homologation 2382

Transformation of carbon dioxide.

Background Since at least 400 C.E., when the Mayans first used layered clays to make dyes, people have been harnessing the properties of layered materials. This gradually developed into scientific research, leading to the elucidation of the laminar structure of layered materials, detailed understanding of their properties, and eventually experiments to exfoliate or delaminate them into individual, atomically thin nanosheets. This culminated in the discovery of graphene, resulting in a new explosion of interest in two-dimensional materials. Layered materials consist of two-dimensional platelets weakly stacked to form three-dimensional structures. The archetypal example is graphite, which consists of stacked graphene monolayers. However, there are many others: from MoS 2 and layered clays to more exotic examples such as MoO 3 , GaTe, and Bi 2 Se 3 . These materials display a wide range of electronic, optical, mechanical, and electrochemical properties. Over the past decade, a number of methods have been developed to exfoliate layered materials in order to produce monolayer nanosheets. Such exfoliation creates extremely high-aspect-ratio nanosheets with enormous surface area, which are ideal for applications that require surface activity. More importantly, however, the two-dimensional confinement of electrons upon exfoliation leads to unprecedented optical and electrical properties. Liquid exfoliation of layered crystals allows the production of suspensions of two-dimensional nanosheets, which can be formed into a range of structures. (A) MoS 2 powder. (B) WS 2 dispersed in surfactant solution. (C) An exfoliated MoS 2 nanosheet. (D) A hybrid material consisting of WS 2 nanosheets embedded in a network of carbon nanotubes. Advances An important advance has been the discovery that layered crystals can be exfoliated in liquids. There are a number of methods to do this that involve oxidation, ion intercalation/exchange, or surface passivation by solvents. However, all result in liquid dispersions containing large quantities of nanosheets. This brings considerable advantages: Liquid exfoliation allows the formation of thin films and composites, is potentially scaleable, and may facilitate processing by using standard technologies such as reel-to-reel manufacturing. Although much work has focused on liquid exfoliation of graphene, such processes have also been demonstrated for a host of other materials, including MoS 2 and related structures, layered oxides, and clays. The resultant liquid dispersions have been formed into films, hybrids, and composites for a range of applications. Outlook There is little doubt that the main advances are in the future. Multifunctional composites based on metal and polymer matrices will be developed that will result in enhanced mechanical, electrical, and barrier properties. Applications in energy generation and storage will abound, with layered materials appearing as electrodes or active elements in devices such as displays, solar cells, and batteries. Particularly important will be the use of MoS 2 for water splitting and metal oxides as hydrogen evolution catalysts. In addition, two-dimensional materials will find important roles in printed electronics as dielectrics, optoelectronic devices, and transistors. To achieve this, much needs to be done. Production rates need to be increased dramatically, the degree of exfoliation improved, and methods to control nanosheet properties developed. The range of layered materials that can be exfoliated must be expanded, even as methods for chemical modification must be developed. Success in these areas will lead to a family of materials that will dominate nanomaterials science in the 21st century.

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Liquid Exfoliation of Layered Materials

Due to their abundance, high strength and stiffness, low weight and biodegradability, nano-scale cellulose fiber materials (e.g., microfibrillated cellulose and bacterial cellulose) serve as promising candidates for bio-nanocomposite production. Such new high-value materials are the subject of continuing research and are commercially interesting in terms of new products from the pulp and paper industry and the agricultural sector. Cellulose nanofibers can be extracted from various plant sources and, although the mechanical separation of plant fibers into smaller elementary constituents has typically required high energy input, chemical and/or enzymatic fiber pre-treatments have been developed to overcome this problem. A challenge associated with using nanocellulose in composites is the lack of compatibility with hydrophobic polymers and various chemical modification methods have been explored in order to address this hurdle. This review summarizes progress in nanocellulose preparation with a particular focus on microfibrillated cellulose and also discusses recent developments in bio-nanocomposite fabrication based on nanocellulose.

Microfibrillated cellulose and new nanocomposite materials: a review

Hyperbranched polymers: from synthesis to applications

Decomposition of polycarbonate in subcritical and supercritical water

Preparation of cellulose-polymerized ionic liquid composite by in-situ polymerization of polymerizable ionic liquid in cellulose-dissolving solution

In this study, a new preparation method of hydroxy double salts (HDSs) including organic compounds between layers has been established in which the HDSs were prepared by reacting ZnO with organic metal salts in water. This method does not need an anion-exchange reaction to incorporate organic compounds into the HDS layers. Moreover, the reaction proceeds under mild conditions around room temperature, and the obtained HDSs showed high crystallinity compared to those obtained by an anion-exchange reaction. We prepared ZnO crystals having a thin-plate structure by the thermal treatment of hydroxy zinc acetate at 873 K.

Effects of Zinc on the New Preparation Method of Hydroxy Double Salts

In this article we describe a new method of polymerization called “vine-twining polymerization” for preparation of well-defined supramolecules, which are amylose–polymer inclusion complexes. The method was achieved by enzymatic polymerization of α-D-glucose-1-phosphate catalyzed by phosphorylase in the presence of various synthetic polymers such as polyethers, polyesters, poly(ester–ether), and amphiphilic block copolymer. Powder X-ray diffraction (XRD) and 1H-NMR measurements determined the structures of the products to be inclusion complexes. The XRD patterns were completely different from those of amylose and guest polymers. The 1H-NMR spectra of the products indicated that the structures were composed of amylose and guest polymers. The formation process of the inclusion complexes during the enzymatic polymerization was also evaluated. In addition, we revealed that the bulkiness of the end groups and the hydrophobicity of the guest polymers strongly affected the formation of the inclusion complexes. By means of this method of polymerization, a graft polymer having inclusion complexes as side chains was prepared. Furthermore, as an evolution of the “vine-twining polymerization,” we attempted a system of parallel polymerization to form an inclusion complex of amylose with a strongly hydrophobic guest polymer. © 2005 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 5: 36–46; 2005: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20031

Vine-twining polymerization: a new preparation method for well-defined supramolecules composed of amylose and synthetic polymers.

Synthesis of an amylose–polymer inclusion complex by enzymatic polymerization of glucose 1-phosphate catalyzed by phosphorylase enzyme in the presence of polyTHF: a new method for synthesis of polymer–polymer inclusion complexes

Jun-ichi Kadokawa

Papers

Decomposition of polycarbonate in subcritical and supercritical water

Preparation of cellulose-polymerized ionic liquid composite by in-situ polymerization of polymerizable ionic liquid in cellulose-dissolving solution

Effects of Zinc on the New Preparation Method of Hydroxy Double Salts

Vine-twining polymerization: a new preparation method for well-defined supramolecules composed of amylose and synthetic polymers.

Synthesis of an amylose–polymer inclusion complex by enzymatic polymerization of glucose 1-phosphate catalyzed by phosphorylase enzyme in the presence of polyTHF: a new method for synthesis of polymer–polymer inclusion complexes