▎ 摘　　要

Ultrathin Co3O4 nanotube-intercalated graphene composites were synthesized using a facile one-step hydrothermal method in a mixture of ionic liquid and ethanol. No templates were used to form the Co3O4 nanotubes. The electrode modified as-prepared composites exhibited a high specific capacitance of 1010 F g(-1) at a high discharge current of 5 A g(-1), as well as excellent cycling stability (89.2% capacitance retention after 5000 cycles). (C) 2015 Elsevier B.V. All rights reserved.