Electrostatic-induced assembly of graphene-encapsulated carbon@nickel-aluminum layered double hydroxide core-shell spheres hybrid structure for high-energy and high-power-density asymmetric supercapacitor

Wu, Shuxing, Hui, Kwan San, Hui, Kwun Nam and Kim, Kwang Ho (2017) Electrostatic-induced assembly of graphene-encapsulated carbon@nickel-aluminum layered double hydroxide core-shell spheres hybrid structure for high-energy and high-power-density asymmetric supercapacitor. ACS Applied Materials & Interfaces, 9 (2). 1395–1406. ISSN 1944-8244

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Abstract

Achieving high energy density while retaining high power density is difficult in electrical double-layer capacitors and in pseudocapacitors considering the origin of different charge storage mechanisms. Rational structural design became an appealing strategy in circumventing these trade-offs between energy and power densities. A hybrid structure consists of chemically converted graphene-encapsulated carbon@nickel-aluminum layered double hydroxide core–shell spheres as spacers among graphene layers (G-CLS) used as an advanced electrode to achieve high energy density while retaining high power density for high-performance supercapacitors. The merits of the proposed architecture are as follows: (1) CLS act as spacers to avoid the close restacking of graphene; (2) highly conductive carbon sphere and graphene preserve the mechanical integrity and improve the electrical conductivity of LDHs hybrid. Thus, the proposed hybrid structure can simultaneously achieve high electrical double-layer capacitance and pseudocapacitance resulting in the overall highly active electrode. The G-CLS electrode exhibited high specific capacitance (1710.5 F g−1 at 1 A g−1) under three-electrode tests. An ASC fabricated using the G-CLS as positive electrode and reduced graphite oxide as negative electrode demonstrated remarkable electrochemical performance. The ASC device operated at 1.4 V, and delivered a high energy density of 35.5 Wh kg−1 at a 670.7 W kg−1 power density at 1 A g−1 with an excellent rate capability, as well as a robust long-term cycling stability of up to 10 000 cycles.

Item Type: Article
Uncontrolled Keywords: asymmetric supercapacitor,graphene,carbon sphere,nickel−aluminum layered double hydroxide,electrostatic assembly
Faculty \ School: Faculty of Science > School of Mathematics
Depositing User: Pure Connector
Date Deposited: 20 Dec 2016 00:08
Last Modified: 22 Jul 2020 01:17
URI: https://ueaeprints.uea.ac.uk/id/eprint/61782
DOI: 10.1021/acsami.6b09355

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