Preparation of Ni(OH)2-graphene sheet-carbon nanotube composite as electrode material for supercapacitors

• Published in: Journal of alloys and compounds Vol. 618; pp. 37 - 43
• Main Authors: Liu, Y.F., Yuan, G.H., Jiang, Z.H., Yao, Z.P., Yue, M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.01.2015
• Subjects: Carbon nanotube; Graphene sheets; Ni(OH)2; Solvothermal reaction; Supercapacitor; Carbon nanotube; Supercapacitor; Ni(OH)2; Solvothermal reaction; Graphene sheets
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2014.08.167

•CNT is introduced into graphene to prevent restacking by solvothermal reaction.•Ethanol as a low cost and green solvent is used in solvothermal reaction.•Ni(OH)2 nanosheets were chemically precipitated into GS-CNT to increase the capacitance. Ni(OH)2-graphene sheet-carbon nanotube composite was prepared for supercapacitance materials through a simple two-step process involving solvothermal synthesis of graphene sheet-carbon nanotube composite in ethanol and chemical precipitation of Ni(OH)2. According to N2 adsorption/desorption analysis, the Brunauer–Emmett–Teller surface area of graphene sheet-carbon nanotube composite (109.07m2g−1) was larger than that of pure graphene sheets (32.06m2g−1), indicating that the added carbon nanotubes (15wt.%) could prevent graphene sheets from restacking in the solvothermal reaction. The results of field emission scanning electron microscopy and transmission electron microscopy showed that Ni(OH)2 nanosheets were uniformly loaded into the three-dimensional interconnected network of graphene sheet-carbon nanotube composite. The microstructure enhanced the rate capability and utilization of Ni(OH)2. The specific capacitance of Ni(OH)2-graphene sheet-carbon nanotube composite was 1170.38Fg−1 at a current density of 0.2Ag−1 in the 6molL−1 KOH solution, higher than those provided by pure Ni(OH)2 (953.67Fg−1) and graphene sheets (178.25Fg−1). After 20cycles at each current density (0.2, 0.4, 0.6, 0.8, 1.0 and 1.2Ag−1), the capacitance of Ni(OH)2-graphene sheet-carbon nanotube composite decreased 26.96% of initial capacitance compared to 74.52% for pure Ni(OH)2.