Structure and electrochemical performance of graphene/porous carbon coated carbon nanotube composite for supercapacitors

• A facile route for preparing RGO/CNT@AC composite is developed.
• Introducing CNT@AC instead of CNT among RGOs is beneficial to specific capacitance.
• RGO/CNT@AC composite exhibits superior specific capacitance and rate performance.

A composite of graphene/porous carbon coated carbon nanotube (denoted as RGO/CNT@AC) is synthesized. Microstructural characterization of the RGO/CNT@ AC composite shows that the CNTs are uniformly coated by activated porous carbons, and the porous carbon coated CNTs are inserted among graphene sheets. Electrochemical investigations indicate that the specific capacitance of the RGO/CNT@AC composite is up to 147 F g−1 at 10 mV s−1, an 56% improvement compared with that of graphene/pure CNT (denoted as RGO/CNT) composite. Furthermore, the cyclic voltammogram curves of the RGO/CNT@AC composite can keep a rectangular-like shape even at a scan rate of 5000 mV s−1, showing a significantly better rate capability. The improvement in supercapacitive performance of the RGO/CNT@AC composite may be attributable to the contribution of porous carbon to specific capacitance, the effective inhibition the restacking of graphene sheets and the construction of more mutually connected electrolyte ions transport paths by the shortened porous carbon coated CNTs among graphene sheets. The superior specific capacitance and rate performance imply that the RGO/CNT@AC composite is promising for supercapacitors.