title: 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.
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-1at 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-1at a 670.7 W kg-1power density at 1 A g-1with an excellent rate capability as well as a robust long-term cycling stability of up to 10 000 cycles.
authors.affiliation: Department of Materials Science and Engineering, Pusan National University , San 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735, Republic of Korea.
authors.forename: Shuxing
authors.initials: S
authors.lastname: Wu
authors.affiliation: School of Mathematics, University of East Anglia , Norwich NR4 7TJ, United Kingdom.
authors.forename: Kwan San
authors.initials: KS
authors.lastname: Hui
authors.affiliation: Institute of Applied Physics and Materials Engineering, University of Macau , Avenida da Universidade, Macau, China.
authors.forename: Kwun Nam
authors.initials: KN
authors.lastname: Hui
authors.affiliation: Department of Materials Science and Engineering, Pusan National University , San 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735, Republic of Korea.|Global Frontier R&D Center for Hybrid Interface Materials, Pusan National University , 30 Jangjeon-dong, Geumjung-gu, Busan 609-735, South Korea.
authors.forename: Kwang Ho
authors.initials: KH
authors.lastname: Kim
keywords: asymmetric supercapacitor; carbon sphere; electrostatic assembly; graphene; nickel−aluminum layered double hydroxide