Phosphorus dual-site driven CoS2@S, N co-doped porous carbon nanosheets for flexible quasi-solid-state supercapacitors

Liu, Shude, Gao, Daqiang, Li, Junfu, Hui, Kwan San, Yin, Ying, Hui, Kwun Nam and Chan Jun, Seong (2019) Phosphorus dual-site driven CoS2@S, N co-doped porous carbon nanosheets for flexible quasi-solid-state supercapacitors. Journal of Materials Chemistry A, 7 (46). pp. 26618-26630. ISSN 2050-7488

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Abstract

Battery-type electrode materials typically suffer from intrinsically slow faradaic reaction kinetics, which severely limits the energy and power density of supercapacitors. Herein, we develop a hybrid of P-doped CoS2 (P-CoS2) nanoparticles confined in highly conductive P, S, N tri-doped carbon (P, S, N-C) porous nanosheets grown on carbon fibers through in situ thermal conversion of a metal–organic framework, followed by sulfurization and phosphorization. In this structural architecture, the heteroatom-enriched porous carbon nanosheets serve as a protective coating to inhibit changes in the volume of the P-CoS2 nanoparticles and offer efficient pathways for rapid charge transfer. The nanosized P-CoS2 substantially shortens the electrolyte ion diffusion distance and shows enhanced covalency after the introduction of P atoms, resulting in decreased migration energy of electrons during the redox reaction. In particular, the P dopants exhibit improved electrical conductivity and reduced adsorption energy between OH− and the nuclear Co atoms in P-CoS2, evidenced by density functional theory calculations. The designed P-CoS2@P, S, N-C electrode exhibits excellent rate capability and long-term cycling stability. Moreover, flexible solid-state asymmetric supercapacitor devices with P-CoS2@P, S, N-C as the cathode and Co@P, N-C as the anode deliver a high energy density of 56.4 W h kg−1 at 725 W kg−1 and a capacitance retention of 94.1% over 5000 cycles at 20 A g−1. The devices also exhibit uniform performance and outstanding bendability with slight capacitance decay under different bending conditions.

Item Type: Article
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Depositing User: LivePure Connector
Date Deposited: 24 Jan 2020 03:27
Last Modified: 11 Jun 2020 01:22
URI: https://ueaeprints.uea.ac.uk/id/eprint/73771
DOI: 10.1039/C9TA09646A

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