Carbon nanotube/graphene composites were directly grown on cobalt (Co) catalysts-coated nickel foam by one-step ambient pressure CVD. Next, The silicon film was deposited on the carbon nanotube/graphene composites by RF magnetron sputtering at different power levels (150 and 200 W). Finally, the silicon/carbon nanotube/graphene composites were modified by RF nitrogen-plasma treatment at different power levels (50, 75, and 100 W). The silicon film sputtered on the carbon nanotube/graphene composites at a lower power level possessed higher specific capacity and cyclic stability due to the silicon thin film sputtered on the carbon nanotube/graphene composites at 150 W with loose microstructure . Furthermore, the higher the nitrogen-plasma power, the higher the cyclic stability because a conductive Li3N matrix primarily was derived from SiN0.73 , the higher the power, the higher the percentage of SiN0.73 as well as then the higher the percentage of ductile and conductive Li3N which buffered volume expansion of the Si-Li alloy as well as prevented aggregation of the Si nanoparticles [4, 5]. However, the higher the nitrogen-plasma power, the lower the specific capacity since the higher the power, the higher the percentage of nonconductive SiN1.33 which led to the lower specific capacity . Moreover, silicon/carbon nanotube/graphene composites modified by nitrogen-plasma showed a stable cyclic performance in comparison to silicon/carbon nanotube/graphene composites since the incorporation of nitrogen improved the cyclic stability of the anode [4, 5].
Keywords: silicon/carbon nanotube/graphene composites; chemical vapor deposition; magnetron sputtering; nitrogen-plasma treatment; lithium-ion batteries
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