Ni Foam-Ni3S2@Ni(OH)2-Graphene Sandwich Structure Electrode Materials: Facile Synthesis and High Supercapacitor Performance

A novel Ni foam-Ni3S2@Ni(OH)(2)-graphene sandwich- structured electrode (NF-NN-G) with high areal mass loading (8.33 mgcm(-2)) has been developed by sulfidation and hydrolysis reactions. The conductivity of Ni3S2 and Ni(OH)(2) were both improved. The upper layer of Ni(OH)(2), covered with a thin graphene film, is formed in situ from the surface of the lower layer of Ni3S2, whereas the Ni3S2 grown on Ni foam substrate mainly acts as a rough support bridging the Ni(OH)(2) and Ni foam. The graphene stabilized the Ni(OH)(2) and the electrochemical properties were effectively enhanced. The as-synthesized NF-NN-G-5mg electrode shows a high specific capacitance (2258 Fg(-1) at 1 Ag-1 or 18.81 F cm(-2) at 8.33 mAcm(-2)) and an outstanding rate property (1010 Fg(-1) at 20 Ag-1 or 8.413 Fcm(-2) at 166.6 mAcm(-2)). This result is around double the capacitance achieved in previous research on Ni3S2@ Ni(OH)(2)/3 DGN composites (3DGN= three-dimensional graphene network). In addition, the asfabricated NF-NN-G-5mg composite electrode has an excellent cycle life with no capacitance loss after 3000 cycles, indicating a potential application as an efficient electrode.