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Issue 20, 2019
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Integrating ultrathin and modified NiCoAl-layered double-hydroxide nanosheets with N-doped reduced graphene oxide for high-performance all-solid-state supercapacitors

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Abstract

As one class of important electroactive materials, layered double-hydroxide (LDH) nanostructures show great promise for application in the fields of electrocatalysis, secondary batteries, and supercapacitors. Nonetheless, the synthesis of ultrathin multi-metallic-based LDH nanosheets or related nanohybrids (NHs) remains a challenge, and their supercapacitive performances need to be further improved for achieving both high energy and high power densities. Herein, ultrathin and modified NiCoAl-LDH (m-LDH) nanosheets and N-doped reduced graphene oxide (NRG) NHs were synthesized by an alkaline etching of pre-synthesized ultrathin NiCoAl-LDH nanosheets, followed by electrostatic assembly with NRG. The alkaline etching could efficiently modulate the chemical states of the active Ni/Co elements and create more oxygen vacancies in the m-LDH nanosheets. After integrating m-LDH with NRG, the strong interaction or efficient electronic coupling of those two constituents further mediated the surface electronic structure of the m-LDH nanosheets, improving the interfacial charge transport and offering more available electrochemical active sites for surface faradaic reactions. Thus, the obtained m-LDH/NRG NHs manifested greatly enhanced specific capacitance (1877.0 F g−1 at 1 A g−1), which was superior to that of pure m-LDH and most other reported electrode materials. Moreover, using such NHs as the positive electrode and activated carbon as the negative electrode, a fabricated asymmetric all-solid-state supercapacitor device delivered a high energy density of 19.9 W h kg−1 at a power density of 319.8 W kg−1 together with good cycling stability (76.5% capacitance retention after over 5000 cycles). Remarkably, even at a power density up to 1637.5 W kg−1, it could still retain an energy density of 13.1 W h kg−1, superior to recently reported asymmetric supercapacitors devices based on Ni, Co, and other transition metal compounds.

Graphical abstract: Integrating ultrathin and modified NiCoAl-layered double-hydroxide nanosheets with N-doped reduced graphene oxide for high-performance all-solid-state supercapacitors

  • This article is part of the themed collection: Nanocarbons
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Publication details

The article was received on 18 Mar 2019, accepted on 26 Apr 2019 and first published on 26 Apr 2019


Article type: Paper
DOI: 10.1039/C9NR02357G
Nanoscale, 2019,11, 9896-9905

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    Integrating ultrathin and modified NiCoAl-layered double-hydroxide nanosheets with N-doped reduced graphene oxide for high-performance all-solid-state supercapacitors

    F. Liu, Y. Chen, Y. Liu, J. Bao, M. Han and Z. Dai, Nanoscale, 2019, 11, 9896
    DOI: 10.1039/C9NR02357G

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