Carbon-Based Fibrous EDLC Capacitors and Supercapacitors

This paper investigates electrochemical double-layer capacitors (EDLCs) including two alternative types of carbon-based fibrous electrodes, a carbon fibre woven fabric (CWF) and a multiwall carbon nanotube (CNT) electrode, as well as hybrid CWF-CNT electrodes. Two types of separator membranes were also considered. An organic gel electrolyte PEO-LiCIO4-EC-THF was used to maintain a high working voltage. The capacitor cells were tested in cyclic voltammetry, charge-discharge, and impedance tests. The best separator was a glass fibre-fine pore filter. The carbon woven fabric electrode and the corresponding supercapacitor exhibited superior performance per unit area, whereas the multiwall carbon nanotube electrode and corresponding supercapacitor demonstrated excellent specific properties. The hybrid CWF-CNT electrodes did not show a combined improved performance due to the lack of carbon nanotube penetration into the carbon fibre fabric

Cross-linked single-walled carbon nanotube aerogel electrodes via reductive coupling chemistry

Single-walled carbon nanotube (SWCNT) anions can be cross-linked by a dielectrophile to form covalent, carbon-bonded organogels. Freeze-drying produces cryogels with low density (2.3 mg cm−3), high surface area (766 m2 g−1), and high conductivity (9.4 S m−1), showing promise as supercapacitor electrodes. Counterion concentration controls debundling, grafting ratio, as well as all the resulting properties

Design of Porous Carbons for Supercapacitor Applications for Different Organic Solvent-Electrolytes

The challenge of optimizing the pore size distribution of porous electrodes for different electrolytes is encountered in supercapacitors, lithium-ion capacitors and hybridized battery-supercapacitor devices. A volume-averaged continuum model of ion transport, taking into account the pore size distribution, is employed for the design of porous electrodes for electrochemical double-layer capacitors (EDLCs) in this study. After validation against experimental data, computer simulations investigate two types of porous electrodes, an activated carbon coating and an activated carbon fabric, and three electrolytes: 1.5 M TEABF4 in acetonitrile (AN), 1.5 M TEABF4 in propylene carbonate (PC), and 1 M LiPF6 in ethylene carbonate:ethyl methyl carbonate (EC:EMC) 1:1 v/v. The design exercise concluded that it is important that the porous electrode has a large specific area in terms of micropores larger than the largest desolvated ion, to achieve high specific capacity, and a good proportion of mesopores larger than the largest solvated ion to ensure fast ion transport and accessibility of the micropores.</jats:p

Supercapacitors with lithium-ion electrolyte: An experimental study and design of the activated carbon electrodes via modelling and simulations

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2021 roadmap on lithium sulfur batteries

Batteries that extend performance beyond the intrinsic limits of Li-ion batteries are among the most important developments required to continue the revolution promised by electrochemical devices. Of these next-generation batteries, lithium sulfur (Li–S) chemistry is among the most commercially mature, with cells offering a substantial increase in gravimetric energy density, reduced costs and improved safety prospects. However, there remain outstanding issues to advance the commercial prospects of the technology and benefit from the economies of scale felt by Li-ion cells, including improving both the rate performance and longevity of cells. To address these challenges, the Faraday Institution, the UK's independent institute for electrochemical energy storage science and technology, launched the Lithium Sulfur Technology Accelerator (LiSTAR) programme in October 2019. This Roadmap, authored by researchers and partners of the LiSTAR programme, is intended to highlight the outstanding issues that must be addressed and provide an insight into the pathways towards solving them adopted by the LiSTAR consortium. In compiling this Roadmap we hope to aid the development of the wider Li–S research community, providing a guide for academia, industry, government and funding agencies in this important and rapidly developing research space

Investigations of Activated Carbon Fabric-Based Supercapacitors with Different Interlayers Via Experiments and Modelling of Electrochemical Processes of Different Timescales

This study includes a novel approach of applying an equivalent electric circuit model of two resistors and three constant phase elements (CPEs) to the galvanostatic charge-discharge of supercapacitors which provides virtual monitoring of the electrochemical processes taking place in parallel at different timescales and offers remarkable insights into the coexistence composition and cascade of such processes during the charge-discharge of cells at different current densities. This modelling method has been applied to analyse the performance of high energy density supercapacitors based on a microporous, phenolic-derived, activated carbon fabric (ACF) with different interlayers with the current collector (CC). Associated experimental studies deal with the challenge of overcoming the high contact resistance between the ACF and the current collector (CC) by employing innovative interlayers containing conductive features or structures to fill or bridge the interface gaps between the ACF fibers and the CC foil and the pores of the activated carbon (AC) fiber surface. Such interlayers involve tree-like microstructures of carbon black nanoparticles or deflocculated graphite platelets or multiwall carbon nanotubes (MWCNTs) deposited electrophoretically on the aluminium foil and the ACF. The use of PEDOT:PSS binder in such interlayer raises performance to maximum 44 Wh/kg and 9 kW/kg for electrolyte 1.5 M TEABF4/AN. These are further raised by 17% and 13%, respectively, using electrolyte 1.5 M SBPBF4/AN, and by 19% (both) using a thin polyolefinic separator against the thicker, cellulose-based separator