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Polymers for Supercapacitors
Published in Soney C George, Sam John, Sreelakshmi Rajeevan, Polymer Nanocomposites in Supercapacitors, 2023
Sreelakshmi Rajeevan, Sam John, Soney C George
GPEs are quasi-solid-state polymer electrolytes with substantial volumes of liquid, they differ significantly from SPEs. GPEs are made of salts and solvents that are commonly found in liquid electrolytes. The GPEs’ gel consistency is the result of a synergistic impact between solid polymer cohesive capabilities and liquid electrolyte diffusive qualities. The trapping of liquid electrolytes raises the polymer’s amorphous content and lowers the glass transition temperature to around -40 °C, increasing ion mobility and resulting in better ionic conductivity of the GPEs. The high ionic conductivity at room temperature (10–4 to 10–3 S/cm), which is nearly equivalent to liquid electrolytes has greatly enhanced the adoption of GPEs as electrolytes or separators. Polymers such as polyvinyl alcohol (PVA) (32), polymethylmethacrylate (PMMA) (33–34), PVDF (35), P(VDF-HFP) (36), polyacrylonitrile (PAN) (37), and polyethylene oxide (PEO) have all been used to create electrolyte systems.
Solid-State Electrolytes for Lithium-Ion Batteries
Published in Prasanth Raghavan, Fatima M. J. Jabeen, Ceramic and Specialty Electrolytes for Energy Storage Devices, 2021
Jabeen Fatima M. J., P. P. Abhijith, N. S. Jishnu, Das Akhila, Neethu T.M. Balakrishnan, Jou-Hyeon Ahn, Prasanth Raghavan
Lithium-ion batteries (LIBs) are the most popular among electrochemical energy storage devices and have a monopoly on powering the electronic gadgets and zero-emission automobile market due to their relatively high energy density, higher output voltage, negligible self-discharge, and lack of a memory effect [1–4]. A conventional lithium-ion battery comprises two electrodes, an anode and a cathode, and an electrolyte system, as shown in Figure 1.1. The electrolyte is one of the key components and is known as the heart of the battery, acting as the ion transport pathway between the positive and negative electrode. The cell capacity, working temperature range, safety, electrochemical performance, and cyclability of lithium-ion batteries are enhanced by adopting the electrolyte system. According to their physical state, electrolytes can be broadly classified into liquid electrolytes, quasi-solid electrolytes, gel electrolytes, and solid electrolytes (SEs).
Seeing Giant Micelles by Cryogenic-Temperature Transmission Electron Microscopy (Cryo-TEM)
Published in Raoul Zana, Eric W. Kaler, Giant Micelles, 2007
The reduction of vapor pressure and arresting supramolecular motion is called “fixation,” that can be either chemical or physical (thermal). Chemical fixation involves addition of a chemical substance alien to the sample. Because nano-structured liquids, particularly surfactant-based systems, are very sensitive to changes in composition, addition of compounds such as a stain (a substance that enhances contrast) or fixative, followed in some cases by a chemical reaction between the fixative and the specimen, and often by drying of sample, may alter the original nanostructures in the system. Thus, chemical fixation is unacceptable (in most cases) for the study of nanostructured liquids. Hence, the method of choice is thermal fixation, that is, ultrafast cooling of the liquid specimens into a vitrified or quasi-solid state. This is achieved by rapidly plunging the specimen into a suitable cryogen. Because thermal diffusivities are larger than mass diffu-sivities, thermal fixation is much more rapid than chemical fixation, and, of course, eliminates the addition of an alien compound to the system.
A review on the use of carbon matrix incorporated with macrocyclic metal complexes as counter electrodes for platinum free dye sensitized solar cells
Published in Journal of Coordination Chemistry, 2021
Kirandeep Kaur, Meenakshi Patyal, Nidhi Gupta
The electrolyte should have transparency to visible light and not react with the dye molecules [48]. Three types of electrolytes have been used in DSSCs: liquid electrolytes, solid-state electrolytes such as ionic-liquid–based imidazolinium salts, and quasi-solid gel forms of electrolytes. Organic and ionic liquid electrolytes are used, where an organic electrolyte is composed of a redox couple and solvent [49]. Among many redox couples, the most commonly used electrolyte in DSSCs is I−/I3−, as it has low light absorption in the visible region, suitable redox potential, and fast dye regeneration [50]. The most crucial component in DSSCs is the photosensitizer dye as it absorbs solar energy and converts it into electrical energy. It should possess high photo, thermal and electrochemical stability. Dye to be selected in a system must absorb maximum portion of light and show absorption in visible region [51]. Dye sensitizers are mainly classified into three groups: Ru(II) complexes, other metal complexes, and metal-free organic sensitizers [52]. Various anchoring and ancillary ligands are attached to these metal complex sensitizers. The anchoring ligand of the complex determines the attaching ability of the sensitizer to the TiO2 surface, while the ancillary ligand tunes the overall properties of the sensitizer. Thus efficiency of the DSSC depends on the type of dye selected as well as anchoring and ancillary ligands attached to it [53]. Considerable work has been done toward the optimization of sensitizers as well as transition metal complexes played a major role in DSSC development, displaying intense metal to ligand charge transfer (MLCT) transitions [11].
Lifetime assessment of structural concrete – multi-scale integrated hygro-thermal-chemo-electrical-mechanistic approach and statistical evaluation
Published in Structure and Infrastructure Engineering, 2022
Figure 10a displays the integral of the above-mentioned mesoscale substances inside crack spaces including corrosion product, ASR gel and unfrozen water (Gong & Maekawa, 2019). The driving force of migration is the gradient of pore pressure caused by each substance. Since the substances are either liquid or quasi-solid, partial pressure gradient as the gaseous mixture could no longer be applicable. In this platform, the densest substance is assumed to primarily occupy the vacant spaces followed by the rest of mixed substances.
A discrete element cohesive particle collision model for the prediction of ash-induced agglomeration
Published in International Journal of Ambient Energy, 2021
Bernhard Gatternig, Jürgen Karl
This concept is aimed at a detailed mathematical description of the single steps leading to particle cohesion resulting in agglomeration of ash-coated bed particles in fluidised bed combustion. The model is limited to cases of coating induced agglomeration, assuming particles to be enveloped in well developed ash layers (as described e.g. by Öhman et al. 2000). The above-mentioned liquid induced cohesion models assume a liquid of low viscosity to be introduced into a particle system, to (partially) cover the particles and finally to form liquid bridges, thus generating the cohesive capillary and viscous forces. This mostly happens in a capillary regime, i.e. Capillary Number . The agglomeration criteria is consequently defined as a sufficient reduction of kinetic energy of the approaching (or rebounding) particles to avoid rupture of the liquid bridge on rebound. In the case of coating induced agglomeration in combustion, however, the system starts with particles coated in a quasi-solid (amorphous) liquid of viscosity 1012 Pas and higher. So, initially, collisions will be non-cohesive and elastic. Once bed temperatures are sufficiently high to have the ash coatings assume liquid behaviour (T > ∼Tg – glass transition temperature), liquid bridges are formed and the particle relative velocity will by reduced mostly by viscous dissipation (viscous regime with ) to cause agglomeration. With even higher temperatures and certain ash compositions a non-agglomerating regime can occur when initial kinetic energy exceeds the rupture strength of liquid bridges. In the practical operating regime of combustions (700–1200°C), however, this effect is negligible. In lieu of this behaviour, the here proposed novel cohesive collision model primarily attempts to determine the transition behaviour between quasi-solid and liquid behaviour of the coatings as a criteria for agglomeration, while including the low viscosity criterion much in the same way as described by Balakin et al. (2013).