A high-rate aqueous symmetric pseudocapacitor based on highly graphitized onion-like carbon/birnessite-type manganese oxide nanohybrids

Makgopa, KEjikeme, PMJafta, CJRaju, KumarZeiger, MPresser, VOzoemena, KI2016-04-142016-04-142015-01Makgopa, K, Ejikeme, P.M, Jafta, C.J, Raju, K, Zeiger, M, Presser, V and Ozoemena, K.I. 2015. A high-rate aqueous symmetric pseudocapacitor based on highly graphitized onion-like carbon/birnessite-type manganese oxide nanohybrids. Journal of Materials Chemistry A, vol. 3, pp 3480-34902050-7488http://pubs.rsc.org/en/content/articlehtml/2015/TA/C4TA06715Khttp://hdl.handle.net/10204/8477Copyright: 2015 Royal Society of ChemistryWe present a study on the pseudocapacitive properties of birnessite-type MnO(sub2) grafted on highly graphitized onion-like carbon (OLC/MnO(sub2)). In a three-electrode setup, we evaluated two different substrates, namely a platinum disc and nickel foam. The OLC/MnO2 nanohybrid exhibited a large specific capacitance (C(subsp)) of 295 and 323 F g(sup-1) (at 1 A g(sup-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(subsp) of 254 F g(sup-1), a specific energy density of 5.6 W h kg(sup-1), and a high power density of 74.8 kW kg(sup-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 (t=40 ms). This high rate handling ability of the OLC/MnO(sub2) nanohybrid, compared to literature reports, promises new opportunities for the development of aqueous-based pseudocapacitors.enSymmetric pseudocapacitorOnion-like carbonNanohybridsOLC/MnO2Manganese oxideA high-rate aqueous symmetric pseudocapacitor based on highly graphitized onion-like carbon/birnessite-type manganese oxide nanohybridsArticleMakgopa, K., Ejikeme, P., Jafta, C., Raju, K., Zeiger, M., Presser, V., & Ozoemena, K. (2015). A high-rate aqueous symmetric pseudocapacitor based on highly graphitized onion-like carbon/birnessite-type manganese oxide nanohybrids. http://hdl.handle.net/10204/8477Makgopa, K, PM Ejikeme, CJ Jafta, Kumar Raju, M Zeiger, V Presser, and KI Ozoemena "A high-rate aqueous symmetric pseudocapacitor based on highly graphitized onion-like carbon/birnessite-type manganese oxide nanohybrids." (2015) http://hdl.handle.net/10204/8477Makgopa K, Ejikeme P, Jafta C, Raju K, Zeiger M, Presser V, et al. A high-rate aqueous symmetric pseudocapacitor based on highly graphitized onion-like carbon/birnessite-type manganese oxide nanohybrids. 2015; http://hdl.handle.net/10204/8477.TY - Article AU - Makgopa, K AU - Ejikeme, PM AU - Jafta, CJ AU - Raju, Kumar AU - Zeiger, M AU - Presser, V AU - Ozoemena, KI AB - We present a study on the pseudocapacitive properties of birnessite-type MnO(sub2) grafted on highly graphitized onion-like carbon (OLC/MnO(sub2)). In a three-electrode setup, we evaluated two different substrates, namely a platinum disc and nickel foam. The OLC/MnO2 nanohybrid exhibited a large specific capacitance (C(subsp)) of 295 and 323 F g(sup-1) (at 1 A g(sup-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(subsp) of 254 F g(sup-1), a specific energy density of 5.6 W h kg(sup-1), and a high power density of 74.8 kW kg(sup-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 (t=40 ms). This high rate handling ability of the OLC/MnO(sub2) nanohybrid, compared to literature reports, promises new opportunities for the development of aqueous-based pseudocapacitors. DA - 2015-01 DB - ResearchSpace DP - CSIR KW - Symmetric pseudocapacitor KW - Onion-like carbon KW - Nanohybrids KW - OLC/MnO2 KW - Manganese oxide LK - https://researchspace.csir.co.za PY - 2015 SM - 2050-7488 T1 - A high-rate aqueous symmetric pseudocapacitor based on highly graphitized onion-like carbon/birnessite-type manganese oxide nanohybrids TI - A high-rate aqueous symmetric pseudocapacitor based on highly graphitized onion-like carbon/birnessite-type manganese oxide nanohybrids UR - http://hdl.handle.net/10204/8477 ER -