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Front. Mater. | doi: 10.3389/fmats.2019.00176

Controlled synthesis of NixCoyS4/rGO composites for constructing high-performance asymmetric supercapacitor

  • 1Central South University, China

Nickel-cobalt sulfides (NixCoyS4) are promising supercapacitor materials for their high capacitance, while the sluggish kinetics in terms of charge transfer limits their power density. To achieve both high energy and power density for the NixCoyS4 - based supercapacitor, sulfur-doped reduced graphene oxide (rGO) is incorporated into NixCoyS4 by an in situ growth – ion exchange strategy to synthesize NixCoyS4/rGO composites. Profited from the synergetic effect between rGO and NixCoyS4, the Ni1.64Co2.40S4/rGO electrode delivers high specific capacitance of 1089 F g-1 at 1 A g-1, and remains 92.6% of its capacitance at 20 A g-1 (1008 F g-1). Asymmetric supercapacitors assembled with active carbon (AC) and Ni1.64Co2.40S4/rGO (Ni1.64Co2.40S4/rGO // AC) offer both high specific capacitance (265.5 F g-1 at 1 A g-1) and superior rate capability at 50 A g-1 (recovering 63.6% of the capacitance determined at 1 A g-1). In addition, the assembled device exhibits a high capacitance retention of 92.6% after 10000 cycles at 10 A g-1, which implies an excellent cyclic stability. Ragone plot reveals that the energy density of Ni1.64Co2.40S4/rGO //AC asymmetric supercapacitor do not vanish as it delivers 30.4 Wh kg-1 at 10 kW kg-1, demonstrating its promising application.

Keywords: Nickel-cobalt sulfides, In-situ growth, High energy density, Asymmetric supercapacitor, High cyclic stability

Received: 29 May 2019; Accepted: 08 Jul 2019.

Edited by:

Shengkui Zhong, Soochow University, China

Reviewed by:

Biao Gao, Wuhan University of Science and Technology, China
Chaopeng Fu, Shanghai Jiao Tong University, China  

Copyright: © 2019 Dong, Wang, Wang, Guo, Li and Yan. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Guochun Yan, Central South University, Changsha, 130012, Hunan Province, China, happyygc@csu.edu.cn