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.
|Number of pages||13|
|Journal||Journal of Materials Chemistry A|
|Publication status||Published - 2019|
Bibliographical noteFunding Information:
This work was partially supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MIST) (No. NRF-2019R1A2C2090443), (NRF-2017M3A7B4041987), Korea Electric Power Corporation (Grant number: R19XO01-23) and the Scholarship from China Scholarship Council of China (CSC NO. 201708260026).
© 2019 The Royal Society of Chemistry.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)