Electroactive edge site-enriched nickel–cobalt sulfide into graphene frameworks for high-performance asymmetric supercapacitors
Electroactive edge site-enriched nickel–cobalt sulfide into graphene frameworks for high-performance asymmetric supercapacitors
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DOI：
10.1039/c5ee03633j
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发表时间：
2016-04
影响因子：
32.5
通讯作者：
Juan-Yu Yang;Chang Yu;Xiaoming Fan;Suxia Liang;Shaofeng Li;Huawei Huang;Zheng Ling;C. Hao;J. Qi
中科院分区：
文献类型：
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作者：
Juan-Yu Yang;Chang Yu;Xiaoming Fan;Suxia Liang;Shaofeng Li;Huawei Huang;Zheng Ling;C. Hao;J. Qi
定制的边缘位点富集的无机物偶联石墨烯杂化物为高性能超级电容器提供了有前途的平台材料。在此，我们报告了一种简单的策略，通过原位化学转化的方法制备边缘位点富集的镍钴硫化物（Ni-Co-S）纳米颗粒修饰在石墨烯框架上，形成集成的混合架构（Ni-Co-S/G）。与柯肯达尔效应相关的阴离子交换反应，例如S2−离子的蚀刻作用，对于边缘位点富集的纳米结构的形成起着至关重要的作用。密度泛函理论（DFT）计算表明，Ni-Co-S边缘位具有较高的电化学活性和对电解液中OH−的强亲和力，这是其电化学性能增强的原因。得益于Ni-Co-S纳米颗粒和导电石墨烯基底的一体化结构，所得Ni-Co-S/G混合电极在电流密度为1 A g-1时具有1492 F g-1的高比电容，当电流密度增加到50 A g-1时，具有96%的上级倍率性能，并且具有优异的电化学稳定性。使用边缘位点富集的Ni-Co-S/G杂化物作为正极和多孔碳纳米片（PCNS）作为负极制造的非对称超级电容器在0.8kW kg-1的功率密度下显示出43.3W h kg-1的高能量密度，并且即使在22.1kW kg-1的高功率密度下也可以保持28.4W h kg-1的能量密度。
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 S2− 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.