Bridging the performance gap between electric double-layer capacitors and batteries with high-energy/high-power carbon nanotube-based electrodes

Abstract

. (2016) Bridging the performance gap between electric doublelayer capacitors and batteries with high-energy/highpower carbon nanotube-based electrodes. Journal of Materials Chemistry A, 4 (38). pp. 14586-14594. ISSN 2050-7488 Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/37425/1/23_July_J_Mater_Chem_revised.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the University of Nottingham End User licence and may be reused according to the conditions of the licence. For more details see: http://eprints.nottingham.ac.uk/end_user_agreement.pdf A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. IntroductionThe development of methods for storing electrical energy from alternative but intermittent power sources such as wind turbines and solar panels is an increasingly-important challenge and two of the most promising electrochemical solutions are batteries and EDLCs (sometimes called ultracapacitors or supercapacitors). 1,2Unlike batteries, in which charge is stored through faradaic charge-transfer reactions, energy is generally stored in EDLCs through simple electrostatic accumulation of charge at the interface between carbon electrodes and liquid electrolytes so these devices can operate at higher charge/discharge rates than batteries (i.e., at higher powers). As no significant structural or chemical changes of the electrode materials occurs during charging/discharging, EDLCs also exhibit significantly longer lifetimes than batteries. 3,4However, because they only store charge at the electrode/electrolyte interface, the specific energies, E s , of EDLCs are generally significantly lower (~4-5 Wh kg −1 ) than those of batteries (~20-400 Wh kg −1 ) and increasing the energies of EDLCs is a important goal with major societal consequences. 5,6In EDLCs, E s = ½CV 2 , where C is the device capacitance and V is the voltage, so increasing E s involves increasing V and/or the specific capacitance of the electrode materials,

Cigarette butt-derived carbons have ultra-high surface area and unprecedented hydrogen storage capacity

“…83 The extent of porosity generated, as measured by the amount of nitrogen adsorbed, increases as activation temperature rises from 600 to 800 o C, which is the normal trend usually observed. 16,20,26,[84][85][86][87][88][89][90][91][92][93][94] The shape of the isotherms indicates that the pore size increases as activation temperature rises, which is the expected trend in line with the fact that increase in overall porosity in activated carbons is usually accompanied with isotherm changes arising from increase in the amount of nitrogen adsorbed, widening of the adsorption knee and increase in pore size. 16,20,26,[84][85][86][87][88][89][90][91][92][93][94] Figure 4B shows the pore size distribution (PSD) curves of the FF-4T carbons, and as expected the pore size distribution broadens as activation temperature rises.…”

A Promising Polymer Blend Electrolytes Based on Chitosan: Methyl Cellulose for EDLC Application with High Specific Capacitance and Energy Density

“…The drops in P d value were due to the re-association of cation and anion to form ion aggregation during rapid charge–discharge process, which obstructs the ionic transport [72]. According to recent study established by Coromina et al, [73], the energy stored in EDLC containing aqueous H 2 SO 4 or ionic liquid electrolytes can be delivered at power densities >1 kW kg −1 . Thus, the performance of these devices bridges the performance gap between those of EDLCs and batteries.…”

The contrasting effects of diethylmethylamine during reduction of protons and oxidation of formic acid in diethylmethylammonium-based protic ionic liquids

“…Ionic liquids are formally defined as materials that are composed entirely of ions and which are liquid below 100 °C [1]. Due to their inherent conductivities and thermal and electrochemical stabilities, ionic liquids are being used in an increasing number of electrochemical applications, including fundamental studies of the electrical double layer [2], investigations into mass and charge transport [3][4], electrochemical sensing [5], batteries [6], supercapacitors [7], and fuel cells [8]. While a large number of ionic liquids can potentially be synthesised, they can be broadly divided into two classes.…”