Intercalation and exfoliation syntheses of high specific surface area graphene and FeC2O4/graphene composite for anode material of lithium ion battery
The high specific surface area graphene sheets with good crystallization could readily be obtained from graphite through weak oxidation, intercalation and exfoliation in alkaline solution. The influence factors of the ratio of C to KMnO4 and the water bath temperature for synthesis of few-layers graphene (FLG) have been systematically investigated. The graphene with high specific surface area of 2013 m2·g−1 and layer numbers of 4–6 were obtained under the ratio of C to KMnO4 of 1:1 and the water bath temperature of 15 °C. In addition, the synthesis mechanism of FLG was analyzed in details. The oxidation occurred in interface locations while sulfate radicals were simultaneously intercalated into the graphite flake, and finally FLG was formed in alkaline condition with the aid of ultrasound. Meanwhile, the electrochemical properties of FLG were investigated as FeC2O4/graphene composite (FGC) for the anode of lithium ion battery. Graphene with a few layers, large specific surface area, and high electrical conductivity was beneficial to improve the cycling performance of FeC2O4 anode. Therefore, the FGC displayed a large reversible capacity of 903 mAh·g−1 in the initial cycle at a current density of 500 mA·g−1 and an excellent cyclic performance of 737 mAh·g−1 after 200 cycles.