On-chip micro-supercapacitors for operation in a wide temperature range

Onion-like carbon (OLC) based micro-supercapacitor electrodes prepared by electrophoretic deposition (EPD) were combined with a eutectic mixture of ionic liquids (IL), producing a micro-supercapacitor which is able to function from -50 degrees C to 80 degrees C. This device was electrochemically characterized by cyclic voltammetry and electrochemical impedance spectroscopy at different scan rates and different temperatures. At 20 degrees C, a capacitance of 1.1 mF.cm(-2) per footprint area of device at 200 mV.s(-1) within 3.7 V was measured, hence a specific energy of 15 mJ.cm(-2) and a specific power of 240 mW.cm(-2). At -50 degrees C, 76% of the capacitance was maintained at 10 mV.s(-1) within 3.7 V. By integrating with IL, this micro-supercapacitor can be potentially used in portable electronic devices that are required to work under temperature extremes. (C) 2013 Elsevier B.V. All rights reserved.