CPC H01G 11/38 (2013.01) [H01G 11/24 (2013.01); H01G 11/48 (2013.01); H01G 11/52 (2013.01); H01G 11/58 (2013.01); H01G 11/86 (2013.01)] | 8 Claims |
1. A supercapacitor comprising one or more units comprising an ionic liquid electrolyte, a membrane separator, and a self-supporting, free-standing supercapacitor electrode adapted for attachment to an electrical circuit characterised by comprising a free-standing rigid or mechanically resilient, electrically-conductive sheet consisting essentially of a matrix of from 70-90% by weight of activated carbon and 5 to 25% by weight conductive carbon; wherein the activated carbon and conductive carbon are uniformly dispersed in from 5 to 20% by weight of a polymer binder; wherein the electrodes are free-standing in that they are not supported by a metal current collector or a metal supporting substrate within the unit; and
wherein the electrodes comprise a main body and a metallised or metallic tab for providing electrical connection to an external circuit; wherein the electrode sheet has a density of greater than 0.4 grams per cm3; the electrode has a specific capacitance of greater than 100 Farads per gram; and the binder comprises a mixture of (i) a conducting polymer; and (ii) a fluorinated polymer, cellulosic material and/or an elastomer.
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