Enhanced electrochemical performance of nickel-cobalt-oxide@reduced graphene oxide//activated carbon asymmetric supercapacitors by the addition of a redox-active electrolyte

Charmaine Lamiel; Yong Rok Lee; Moo Hwan Cho; Dirk Tuma; Jae-Jin Shim

doi:10.1016/j.jcis.2017.08.003

Enhanced electrochemical performance of nickel-cobalt-oxide@reduced graphene oxide//activated carbon asymmetric supercapacitors by the addition of a redox-active electrolyte

J Colloid Interface Sci. 2017 Dec 1:507:300-309. doi: 10.1016/j.jcis.2017.08.003. Epub 2017 Aug 2.

Authors

Charmaine Lamiel¹, Yong Rok Lee¹, Moo Hwan Cho¹, Dirk Tuma², Jae-Jin Shim³

Affiliations

¹ School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeongbuk 38541, Republic of Korea.
² BAM Federal Institute for Materials Research and Testing, D-12200 Berlin, Germany.
³ School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeongbuk 38541, Republic of Korea. Electronic address: jjshim@yu.ac.kr.

PMID: 28802197
DOI: 10.1016/j.jcis.2017.08.003

Abstract

Supercapacitors are an emerging energy-storage system with a wide range of potential applications. In this study, highly porous nickel-cobalt-oxide@reduced graphene oxide (Ni-Co-O@RGO-s) nanosheets were synthesized as an active material for supercapacitors using a surfactant-assisted microwave irradiation technique. The RGO-modified nanocomposite showed a larger specific area, better conductivity, and lower resistivity than the unmodified nanocomposite because the RGO facilitated faster ion diffusion/transport for improved redox activity. The synergistic effect of Ni-Co-O@RGO-s resulted in a high capacitance of 1903Fg^-1 (at 0.8Ag^-1) in a mixed KOH/redox active K₃Fe(CN)₆ electrolyte. The asymmetric Ni-Co-O@RGO-s//AC supercapacitor device yielded a high energy density and power density of 39Whkg^-1 and 7500Wkg^-1, respectively. The porous structure and combination of redox couples from both the electrode and electrolyte provided a highly synergistic effect, which improved the performance of the supercapacitor device.

Keywords: Asymmetric supercapacitor; Nanocomposite; Nickel-cobalt oxide; Redox-active electrolyte; Reduced graphene oxide; Surfactant.