123rd General Meeting of the KCS

Type Poster Presentation
Area Electrochemistry
Room No. Exhibition Hall 2
Time 4월 18일 (목요일) 11:00~12:30
Code ELEC.P-480
Subject Facile synthesis of nickel cobalt hydroxide nanoneedle/graphene hydrogel composite as a binder-free electrode for asymmetric supercapacitor
Authors Jeongmin Kang, Yuanzhe Piao*
Graduate School of Convergence Science and Technol, Seoul National University, Korea
Abstract Nickel cobalt hydroxide nanoneedle/graphene hydrogel nanocomposite is prepared by using a facile two-step method and further explored as a binder-free electrode for asymmetric supercapacitor. First, freestanding graphene hydrogel is prepared at low temperature using mild reducing agent. Second, nickel cobalt hydroxide nanoneedles are embedded in the graphene hydrogel by using hydrothermal method. Hydrophilic functional groups in graphene hydrogel make nickel cobalt hydroxide nanoneedles to be well-dispersed on the graphene nanosheet surface. Additionally, the freestanding property of graphene hydrogel is used to prepare a binder-free electrode, which can improve the energy density of the final generated asymmetric supercapacitors. The nanocomposite shows an excellent capacity of 544 C g-1 at 2 A g-1 in a three-electrode system. Moreover, the binder-free asymmetric supercapacitor achieves excellent performance with an energy density of 32.74 Wh kg-1 at a power density of 320 W kg-1 and good cycling stability with 85% capacitance retention at a current density of 10 mA cm-2 after 5,000 cycles. These excellent electrochemical performances are attributed to the synergistic effects of (1) high redox active material of nickel cobalt hydroxide, (2) hydrophilic functional group in graphene hydrogel for stable growth of nickel cobalt hydroxide, and (3) fast ion transport by the 3D porous network structure of graphene hydrogel. It is expected that the preparation strategy shown in this work can be used to fabricate other 3D structured nanocomposite for related energy devices.
E-mail kjm1222k@snu.ac.kr