Electroactive edge site-enriched nickel–cobalt sulfide into graphene frameworks for high-performance asymmetric supercapacitors. Issue 4 (22nd January 2016)

• Record Type: Journal Article
• Authors: Yang, Juan; Yu, Chang; Fan, Xiaoming; Liang, Suxia; Li, Shaofeng; Huang, Huawei; Ling, Zheng; Hao, Ce; Qiu, Jieshan
• Is Part Of: Energy & environmental science. Volume 9:Issue 4(2016)
• Page Start: 1299
• Page End: 1307
• Publication Date: 2016-01-22
• Subjects: Energy conversion -- Periodicals; Fuel switching -- Periodicals; Environmental sciences -- Periodicals; Environmental chemistry -- Periodicals; 333.79
• DOI: 10.1039/c5ee03633j
• Languages: English
• ISSNs: 1754-5692

Abstract

Abstract : The integrated hybrid architectures composed of edge site-enriched nickel–cobalt sulfide (Ni–Co–S) nanoparticles and graphene as advanced materials for asymmetric supercapacitors are configured, delivering a superb rate capability. Abstract : Tailor-made edge site-enriched inorganics coupled graphene hybrids hold a promising platform material for high-performance supercapacitors. Herein, we report a simple strategy for fabricating edge site-enriched nickel–cobalt sulfide (Ni–Co–S) nanoparticles decorated on graphene frameworks to form integrated hybrid architectures (Ni–Co–S/G) via an in situ chemically converted method. The Kirkendall effect-involved anion exchange reaction, e.g. the etching-like effort of the S 2− ions, plays a crucial role for the formation of the edge site-enriched nanostructure. Density functional theory (DFT) calculations reveal that the Ni–Co–S edge sites have a high electrochemical activity and strong affinity for OH − in the electrolyte, which are responsible for the enhanced electrochemical performance. Benefiting from the integrated structures of Ni–Co–S nanoparticles and conductive graphene substrates, the resultant Ni–Co–S/G hybrid electrodes exhibit a high specific capacitance of 1492 F g −1 at the current density of 1 A g −1, a superior rate capability of 96% when the current density is increased to 50 A g −1, and excellent electrochemical stabilities. An asymmetric supercapacitor fabricated using the edge site-enriched Ni–Co–S/G hybrids as the positive electrode and porous carbon nanosheets (PCNS) as negative electrodes shows a high energy density of 43.3 W h kg −1 at a power density of 0.8 kW kg −1, and an energy density of 28.4 W h kg −1 can be retained even at a high power density of 22.1 kW kg −1 .