Research Article


2012, 5(9): 605–617


Graphene–Nickel Cobaltite Nanocomposite Asymmetrical Supercapacitor with Commercial Level Mass Loading

Huanlei Wang1,2, Chris M. B. Holt1,2, Zhi Li1,2 (*), Xuehai Tan1,2, Babak Shalchi Amirkhiz1,2, Zhanwei Xu1,2, Brian C. Olsen1,2, Tyler Stephenson1,2, and David Mitlin1,2 (*)

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1 Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 2V4, Canada
2 National Institute for Nanotechnology (NINT), National Research Council of Canada, Edmonton, Alberta T6G 2M9, Canada

Keywords: Graphene, nickel cobaltite (NiCo2O4), supercapacitor, energy density, power density
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A high performance asymmetric electrochemical supercapacitor with a mass loading of 10 mg·cm–2 on each planar electrode has been fabricated by using a graphene–nickel cobaltite nanocomposite (GNCC) as a positive electrode and commercial activated carbon (AC) as a negative electrode. Due to the rich number of faradaic reactions on the nickel cobaltite, the GNCC positive electrode shows significantly higher capacitance (618 F·g–1) than graphene–Co3O4 (340 F∙g–1) and graphene–NiO (375 F∙g–1) nanocomposites synthesized under identical conditions. More importantly, graphene greatly enhances the conductivity of nickel cobaltite and allows the positive electrode to charge/discharge at scan rates similar to commercial AC negative electrodes. This improves both the energy density and power density of the asymmetric cell. The asymmetric cell composed of 10 mg GNCC and 30 mg AC displayed an energy density in the range of 19.5 Wh∙kg–1 with an operational voltage of 1.4 V. At high sweep rate, the system is capable of delivering an energy density of 7.6 Wh∙kg–1 at a power density of about 5600 W∙kg–1. Cycling results demonstrate that the capacitance of the cell increases to 116% of the original value after the first 1600 cycles due to a progressive activation of the electrode, and maintains 102% of the initial value after 10000 cycles.
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Graphene–Nickel Cobaltite Nanocomposite Asymmetrical Supercapacitor with Commercial Level Mass Loading. Nano Res. 2012, 5(9): 605–617

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