Ice-templated Self-assembly of VOPO4-Graphene Nanocomposites for Vertically Porous 3D Supercapacitor Electrodes.
A simple ice-templated self-assembly process is used to prepare a three-dimensional (3D) and vertically porous nanocomposite of layered vanadium phosphates (VOPO4) and graphene nanosheets with high surface area and high electrical conductivity. The resulting 3D VOPO4-graphene nanocomposite has a much higher capacitance of 527.9 F g(-1) at a current density of 0.5 A g(-1), compared with ~247 F g(-1) of simple 3D VOPO4, with solid cycling stability. The enhanced pseudocapacitive behavior mainly originates from vertically porous structures from directionally grown ice crystals and simultaneously inducing radial segregation and forming inter-stacked structures of VOPO4-graphene nanosheets. This VOPO4-graphene nanocomposite electrode exhibits high surface area, vertically porous structure to the separator, structural stability from interstacked structure and high electrical conductivity, which would provide the short diffusion paths of electrolyte ions and fast transportation of charges within the conductive frameworks. In addition, an asymmetric supercapacitor (ASC) is fabricated by using vertically porous VOPO4-graphene as the positive electrode and vertically porous 3D graphene as the negative electrode; it exhibits a wide cell voltage of 1.6 V and a largely enhanced energy density of 108 Wh kg(-1).
Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.
Kwang Hoon
KH
Lee
Department of Engineering Science, University of Oxford, Oxford OX1 3PJ, United Kingdom.
Young-Woo
YW
Lee
George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Seung Woo
SW
Lee
Department of Chemical and Biological Engineering, Korea University, Seoul 136-701, Republic of Korea.|KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701, Republic of Korea.
Jeong Sook
JS
Ha
Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.|KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701, Republic of Korea.
Sang-Soo
SS
Lee
Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.
Jeong Gon
JG
Son