Hierarchical porous carbon spheres/graphene composite for supercapacitor with both aqueous solution and ionic liquid. (1st May 2017)

• Record Type: Journal Article
• Authors: Zhang, Ningshuang; Gao, Na; Fu, Chaopeng; Liu, Dan; Li, Shengcai; Jiang, Lanlan; Zhou, Haihui; Kuang, Yafei
• Is Part Of: Electrochimica acta. Volume 235(2017)
• Page Start: 340
• Page End: 347
• Publication Date: 2017-05-01
• Subjects: Hierarchical micro-nano structure -- Enhanced ion-accessible surface -- High energy density -- Supercapacitor; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2017.03.130
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: Hierarchical porous carbon spheres/graphene (CSG) composite was prepared by a simple self-assembled method for supercapacitor electrode materials. Carbon spheres (CS) was chosen as the spacer for graphene due to its submicron size. The morphology and structure of as-prepared samples were characterized by SEM, XRD and N2 adsorption/desorption techniques. As a result, the aggregation of graphene was reduced by CS effectively, which leads to an enhanced specific surface area and more ion-accessible pores. This unique structure is conducive to the penetration/mobility of ions, especially for ionic liquid with large ionic sizes. The electrochemical performance of synthesized CSG was investigated and the composite offered an outstanding capacitive behavior. In the two-electrode system, CSG electrode displayed a specific capacitance of 303.8 F g −1 in KOH and 280.0 F g −1 in [BMIM]BF4 . Remarkably, the CSG//CSG supercapacitor exhibited a high energy density of 87.5 Wh kg −1 in [BMIM]BF4 electrolyte. After 5000 cycles, the specific capacitance of CSG could still remain 95.3% in KOH and 90.1% in [BMIM]BF4 of the initial value, implying good long-term cycle stability of the composite. The outstanding electrochemical performance can be attributed to the novel hierarchical porous structure.