Microwave-assisted synthesis of CoAl-layered double hydroxide/graphene oxide composite and its application in supercapacitors

A microwave-assisted reflux method was used to rapidly synthesize CoAl-layered double hydroxide (CoAl-LDH)/graphene oxide composite. In the synthetic procedure, graphite oxide (GO) was exfoliated to graphene oxide nanosheets in company with the in situ growth of CoAl-LDH. The as-prepared products showed lamellar structures. The aggregation of LDH was effectively prevented by the presence of graphene oxide nanosheets. Electrochemical performances were evaluated by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge tests. All the composites had higher rate capability than pure CoAl-LDH, maintaining about 80% of discharge capacitance when the current density in creased from 1 A g(-1) to 20 A g(-1). A maximum specific capacitance of 772 F g(-1) was obtained at 1 A g(-1) in 6 M KOH solution for the composite containing 12.9% GO. Moreover, the composite exhibited excellent long cycle life with about 73% specific capacitance retained at 6 A g(-1) after 10,000 cycles. (C) 2012 Elsevier Ltd. All rights reserved.