Enhanced high-current capacitive behavior of graphene/CoAl-layered double hydroxide composites as electrode material for supercapacitors

Graphene nanosheets (GNS)/CoAl-layered double hydroxide (CoAl-LDH) composite with a laminated structure is fabricated by a simple refluxing method. It is found that CoAl-LDH lamellar crystallites gradually self-assemble on the graphene oxide (GO) which is reduced to GNS during the refluxing procedure in the presence of urea. The GNS/CoAl-LDH composite has a higher specific surface area (23.4 m2 g−1) and superior electrochemical performance. As electrode material for supercapacitors, the composite shows a maximum specific capacitance of 711.5 F g−1 at low current density of 1 A g−1, and it remains 516.8 F g−1 when the current density increase to 10 A g−1. Furthermore, the capacitance keeps at least about 81% (compare with 64% for that of pure LDH) after 2000 cycles at 10 A g−1, indicating the composite has excellent high-current capacitive behavior.

Graphical abstractCoAl-LDH crystallites grow on graphene sheets by refluxing process and they exhibit excellent high-rate performance and good cycling ability.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Graphene sheets/CoAl-layered double hydroxide composites were synthesized in one pot. ► The composites show laminated structures without well-defined morphologies. ► The composites show superior electrochemical performance at a high current density. ► The composites could have practical applications for supercapacitors.