TY  - JOUR
U1  - Zeitschriftenartikel, wissenschaftlich - begutachtet (reviewed)
A1  - Makgopa, Katlego
A1  - Ejikeme, Paul M.
A1  - Jafta, Charl J.
A1  - Raju, Kumar
A1  - Zeiger, Marco
A1  - Presser, Volker
A1  - Ozoemena, Kenneth I.
T1  - A high-rate aqueous symmetric pseudocapacitor based on highly graphitized onion-like carbon/birnessite-type manganese oxide nanohybrids
JF  - Journal of Materials Chemistry A
N2  - We present a study on the pseudocapacitive properties of birnessite-type MnO 2 grafted on highly graphitized onion-like carbon (OLC/MnO 2 ). In a three-electrode setup, we evaluated two different substrates, namely a platinum disc and nickel foam. The OLC/MnO 2 nanohybrid exhibited a large specific capacitance (C sp ) of 295 and 323 F g -1 (at 1 A g -1 ) for the Pt disc and Ni foam, respectively. In addition, the Ni foam substrate exhibited much higher rate capability (power density) than the Pt disc. A symmetrical two-electrode device, fabricated with the Ni foam, showed a large C sp of 254 F g -1 , a specific energy density of 5.6 W h kg -1 , and a high power density of 74.8 kW kg -1 . These values have been the highest for onion-based electrodes so far. The device showed excellent capacity retention when subjected to voltage-holding (floating) experiments for 50 h. In addition, the device showed a very short time constant ([small tau] = 40 ms). This high rate handling ability of the OLC/MnO 2 nanohybrid, compared to literature reports, promises new opportunities for the development of aqueous-based pseudocapacitors.
Y1  - 2015
UN  - https://nbn-resolving.org/urn:nbn:de:bsz:291:415-3994
SN  - 2050-7488
SS  - 2050-7488
U6  - https://doi.org/10.1039/c4ta06715k
DO  - https://doi.org/10.1039/c4ta06715k
VL  - 3
IS  - 7
SP  - 3480
EP  - 3490
ER  -