| In this article, two kinds of carbon materials were synthesized through chemical vapor deposition(CVD):carbon nanofiber-graphene(CNF/GN)hybrid and ribbon graphene nanofiber(GNF), the electrochemical properties of the two kinds of carbon materials and graphene were studied, and the two materials exhibit excellent lithium storage performance.The main research content is divided into three parts.The first part, graphite oxide(GO) was synthesized from natural graphite powder using a modified Hummers method at first, and the graphene obtained through the high temperature thermal reduction of GO. Then using GO as catalyst carrier synthesised Ni/GO as catalyst and the catalysts were characterized and analysis. Under different temperature, the carbon nanofiber-graphene(CNF/GN)were prepared via CVD reaction in a vertical furnace. Ultimately obtained the optimum growth temperature for CNF when Ni as catalyst is 600 ℃. The second part is on the basis of the previous research. Hybrid carbon nanofiber-graphene nanosheet (CNF/GN) materials with different morphologies were synthesized by CVD method using ethyne as the carbon source and Ni as a catalyst.By adjusting the ethyne flow rate, hybrid materials with different CNF diameters and CNF/GN weight ratios were prepared. The cycling performance and rate capability of the products as electrodes for lithium-ion batteries were investigated and compared. We found that the CNF/GN anodes we synthesized exhibited better lithium storage properties. The materials with a relatively smaller CNF diameter and a lower CNF/GN weight ratio in GN-supported CNF architectures achieved high performance for reversible lithium storage. Optimum synthesis conditions for the experiments is 600 ℃, at the acetylene flow rate of 2 ml min-1. The third part is the synthesis of cubic phase magnesium carbonate as a template, with ethanol as carbon source,through a CVD method at 800 ℃ in the horizontal furnace and finally got a ribbon graphene fiber material. On the electrochemical performance test,we found that compared with the GN obtained from chemical oxidation reduction method,the GNF synthesized via CVD method have better electrical conductivity and better rate performance than the GN. |
