Combination of 1D Ni(OH)2 nanobelts and 2D graphene sheets to fabricate 3D composite hydrogel electrodes with ultrahigh capacitance and superior rate capability. (20th October 2018)

• Record Type: Journal Article
• Authors: He, Chengen; Qiu, Shengqiang; Peng, Haiyan; Zhang, Qing; Han, Xiaoyan; Yang, Yingkui; Shi, Dean; Xie, Xiaolin
• Is Part Of: Composites science and technology. Volume 167(2018)
• Page Start: 155
• Page End: 163
• Publication Date: 2018-10-20
• Subjects: Graphene -- Nickel hydroxide -- Composite hydrogels -- Supercapacitors; Composite materials -- Periodicals; Composite materials; Fibrous composites; Periodicals; 620.118
• DOI: 10.1016/j.compscitech.2018.07.045
• Languages: English
• ISSNs: 0266-3538

Abstract

Abstract: Metal compound/graphene composites have been dominantly fabricated by in-situ intercalation of metal-containing precursors into graphene or graphene oxide (GO) followed by chemical and/or thermal treatment. This process usually leads to the formation of 0D oxide nanoparticles/2D graphene composites with the limited improvements in the supercapacitor performance. Herein a facile two-step method was reported to fabricate 3D porous Ni(OH)2 /graphene composite hydrogels (NiGH) by incorporating the pre-synthesized 1D Ni(OH)2 nanobelts into a GO suspension followed by the hydrothermal process. The resulted hydrogels show large specific surface area (370.6 m 2 /g) and can be directly used as the self-supported electrodes. The NiGH electrode exhibits the specific capacitance up to 1738.3 F/g at 10 mV/s and 1701.5 F/g at 1 A/g, retains 1385.0 F/g at 100 mV/s and 1152.0 F/g at 8 A/g, respectively. The capacitance and rate performance of NiGH are far superior to those of Ni(OH)2 (841.2 F/g at 10 mV/s; 592.5 F/g at 1.0 A/g), graphene hydrogel (207.5 F/g at 10 mV/s), and the control Ni(OH)2 nanoparticle/graphene composite powder (NiGP: 1045.8 F/g at 10 mV/s; 950.8 F/g at 1.0 A/g) prepared by the one-pot hydrothermal processing of Ni salt and GO. Meanwhile, the NiGH electrode also shows lower resistance and higher cycling stability (retaining 100.8% of initial capacitance over 5000 cycles at 5 A/g) as compared to Ni(OH)2, graphene hydrogel, and NiGP due to the efficient combination of pseudo-capacitive 1D Ni(OH)2 nanobelts and conductive 2D graphene sheets to create 3D architectures. Such a facile two-step protocol enables the superiority of ultrathin oxide nanobelts to fabricate 3D graphene-based composite hydrogels for high-performance supercapacitor electrodes. Graphical abstract: 3D Ni(OH)2 nanobelt/graphene composite hydrogels were fabricated by incorporating the pre-synthesized Ni(OH)2 nanobelts into a suspension of graphene oxide followed by hydrothermal treatment. The resulting self-supported electrodes show much better electrochemical performance compared to the powdery Ni(OH)2 nanoparticle/graphene composites prepared by one-pot hydrothermal processing of Ni salts and graphene oxide. Image 1 Highlights: Combining quasi-1D Ni(OH)2 nanobelts with 2D graphene to fabricate 3D hydrogels. Free-standing electrodes with large specific surface area and ultrahigh capacitance. Synergistic improvements in rate capability, interface resistance, and cyclability.