Synthesis of carbon nanotube/graphene composites on Ni foam without additional catalysts by CVD and their nitrogen-plasma treatment for anode materials in lithium-ion batteries

Abstract

To simultaneously synthesize carbon nanotubes and graphene on nickel foam without additional catalysts, one-step ambient pressure chemical vapor deposition (CVD) is used to grow them at different temperatures. Next, adding nitrogen-doped defects to the surface of the carbon nanotube/graphene composites, the carbon nanotube/ graphene composites are modified by RF (radio frequency) nitrogen-plasma treatment at different power levels and time periods. Carbon nanotubes and graphene are simultaneously synthesized by CVD at 800°C. Furthermore, the specific capacity (618 mAh g-1) reaches a maximum at the nitrogen-plasma treatment conditions (power = 100W and time = 15 min). Moreover, it also shows the nearly double improvement of the specific capacity and higher electrochemical stability after carbon nanotube/graphene composites are treated by nitrogen-plasma.