Supercapacitors are high power energy storage devices that store charge by the electrostatic adsorption of ions at the electrode-‐electrolyte interface. NMR methods have recently been developed to study the structure and dynamics of this interface in porous carbon electrode materials.[2,3] Density functional theory calculations and experimental NMR spectra have shown that the chemical shifts observed for adsorbed ions are sensitive to the local structure of the carbon surfaces, aﬀording a new method to characterise carbon structures. In situ NMR experiments performed on working supercapacitors have then allowed us to study the mechanisms of charge storage. Measurements at diﬀerent charge states have revealed that a number of diﬀerent charging mechanisms can operate.[5,6] Ion adsorption, desorption and exchange can all contribute, with the exact mechanism depending on the electrode polarisation and the choice of electrolyte. Further experiments, as well as lattice simulations, on ionic liquids have shown that the lineshape of the resonance arising from adsorbed ions is related to their mobility. This has allowed us to rationalise the diﬀerent power performances of supercapacitors with diﬀerent electrolytes.
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2. Forse, A. C.; Griﬃn, J. M.; Wang, H.; Trease, N. M.; Presser, V.; Gogotsi, Y.; Simon, P.; Grey, C. P. Phys. Chem. Chem. Phys.
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3. Borchardt, L.; Oschatz, M.; Paasch, S.; Kaskel, S.; Brunner, E. Phys. Chem. Chem. Phys. 2013, 15, 15177.
4. Forse, A. C.; Griﬃn, J. M.; Presser, V.; Gogotsi, Y.; Grey, C. P. J. Phys. Chem. C 2014, 118, 7508.
5. Wang, H.; Forse, A. C.; Griﬃn, J. M.; Trease, N. M.; Trognko, L.; Taberna, P.-‐L.; Simon, P.; Grey, C. P. J. Am. Chem. Soc. 2013,
6. Griﬃn, J. M.; Forse, A. C.; Wang, H.; Trease, N. M.; Simon, P.; Grey, C. P. Faraday Disc. 2014, 176, 49.
7. Forse, A. C.; Griﬃn, J. M.; Merlet, C.; Bayley, P. M.; Wang, H.; Simon, P.; Grey, C. P. unpublished-‐work 2015.