title: Engineering three-dimensional hybrid supercapacitors and microsupercapacitors for high-performance integrated energy storage.
abstract: Supercapacitors now play an important role in the progress of hybrid and electric vehicles, consumer electronics, and military and space applications. There is a growing demand in developing hybrid supercapacitor systems to overcome the energy density limitations of the current generation of carbon-based supercapacitors. Here, we demonstrate 3D high-performance hybrid supercapacitors and microsupercapacitors based on graphene and MnO2 by rationally designing the electrode microstructure and combining active materials with electrolytes that operate at high voltages. This results in hybrid electrodes with ultrahigh volumetric capacitance of over 1,100 F/cm(3). This corresponds to a specific capacitance of the constituent MnO2 of 1,145 F/g, which is close to the theoretical value of 1,380 F/g. The energy density of the full device varies between 22 and 42 Wh/l depending on the device configuration, which is superior to those of commercially available double-layer supercapacitors, pseudocapacitors, lithium-ion capacitors, and hybrid supercapacitors tested under the same conditions and is comparable to that of lead acid batteries. These hybrid supercapacitors use aqueous electrolytes and are assembled in air without the need for expensive "dry rooms" required for building today's supercapacitors. Furthermore, we demonstrate a simple technique for the fabrication of supercapacitor arrays for high-voltage applications. These arrays can be integrated with solar cells for efficient energy harvesting and storage systems.
authors.affiliation: Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles, CA 90095; Department of Chemistry, Faculty of Science, Cairo University, Giza 12613, Egypt;
authors.forename: Maher F
authors.initials: MF
authors.lastname: El-Kady
authors.affiliation: Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles, CA 90095;
authors.forename: Melanie
authors.initials: M
authors.lastname: Ihns
authors.affiliation: Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles, CA 90095;
authors.forename: Mengping
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles, CA 90095;
authors.forename: Jee Youn
authors.initials: JY
authors.lastname: Hwang
authors.affiliation: Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles, CA 90095; Department of Chemistry, Tarbiat Modares University, Tehran 14115-175, Iran; and.
authors.forename: Mir F
authors.initials: MF
authors.lastname: Mousavi
authors.affiliation: Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles, CA 90095;
authors.forename: Lindsay
authors.initials: L
authors.lastname: Chaney
authors.affiliation: Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles, CA 90095;
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Lech
authors.affiliation: Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles, CA 90095; Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095 kaner@chem.ucla.edu.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Kaner
keywords: graphene; metal oxide; microsupercapacitor; supercapacitor
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