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Nitrogen-doped graphene encapsulated cobalt iron sulfide as an advanced electrode for high-performance asymmetric supercapacitors

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Abstract

To develop supercapacitors (SCs) with high energy and power densities, a new type of electrode material with unique properties is strongly required. Metal sulfides (MSs) have been recently studied as promising electrode materials for high-performance SCs because they have excellent redox properties, outstanding electrical conductivity, exceptional catalytic activity, and ultra-high specific capacity. However, their large volume changes and poor rate performances seriously hinder their commercial applications. Herein, a novel nitrogen-doped graphene encapsulated cobalt iron sulfide core–shell (Co8FeS8@NG) hybrid was successfully synthesized through a facile, scalable, and single-step in situ hydrothermal technique. The hierarchical core–shell Co8FeS8@NG hybrid was employed as an advanced electrode material for high-performance solid-state asymmetric SCs (ASCs). The Co8FeS8@NG electrode delivers an ultra-high specific capacitance of ∼1374 F g−1 at a current density of 2 A g−1, with tremendous rate capability (∼71.69% of capacitance retention at 40 A g−1) and excellent cycling stability (∼96.1% of capacitance retention after 10 000 cycles). Furthermore, the assembled Co8FeS8@NG//FeS@NG ASC device exhibits an ultra-high energy density of ∼70.4 W h kg−1 at a power density of 0.598 kW kg−1, exceptional power density (∼22.55 kW h kg−1 at 49.5 W h kg−1), and outstanding cycling stability (∼93.7% of initial capacitance after 10 000 cycles). Therefore, these results demonstrate a simple and cost-effective route for the development of new types of NG encapsulated ternary MSs for future electronics.

Graphical abstract: Nitrogen-doped graphene encapsulated cobalt iron sulfide as an advanced electrode for high-performance asymmetric supercapacitors

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Publication details

The article was received on 24 Dec 2018, accepted on 23 Jan 2019 and first published on 23 Jan 2019


Article type: Paper
DOI: 10.1039/C8TA12396A
Citation: J. Mater. Chem. A, 2019, Advance Article

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    Nitrogen-doped graphene encapsulated cobalt iron sulfide as an advanced electrode for high-performance asymmetric supercapacitors

    Y. Al Haj, J. Balamurugan, N. H. Kim and J. H. Lee, J. Mater. Chem. A, 2019, Advance Article , DOI: 10.1039/C8TA12396A

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