Activated carbons from biomass (grass and Camellia japonica) exhibit enhanced CO2 uptake at 25 °C; up to 1.5 mmol g−1 at 0.15 bar, 5.0 mmol g−1 at 1 bar and 21.1 mmol g−1 at 20 bar, and depending on level of activation, have excellent uptake at both low (≤1 bar) and high (20 bar) pressure.

. (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,

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