The Preparation Of Graphene-based Composites And Their Application In Supercapacitors

The motivation of this paper is focuses on exploring a low-cost, environmental, simple, and green method to prepare materials with a good capacitive performance. The structure and morphologies of the materials are investigated by various characterization methods. A super-capacitor was design to accurately evaluate the capacitive performance of the electrode materials. The relative study can be summarized as follows:We carried out a green, simple and cost-effective method to prepare high-performance electrode materials. r GO@CNF was prepared by inserting the bacterial cellulose into the layer of graphene, and then carbonizing them at a certain temperature. The specific capacitance value of r GO@CNF can be up to 263 F/g in three-electrode system because of its unique net structure. The area specific capacitance reaches 54.5 m F/cm2 in a symmetric supercapacitor and retains 95.5% capacitance after 5000 cycles.A facile, environment-friendly, and large-scale hydrothermal method is used to prepare flake-like Co/Al LDHs anode material(1158 F/g). Reduced graphene oxide(r GO) is obtained by a controlled hydrothermal reduction route to convert graphene oxide(GO) to stable graphene solution without reductant. An asymmetric capacitor incorporating the LDHs as the positive electrode and the r GO as the negative electrode and KOH as electrolyte was fabricated. Because of the synergistic effect, the experimental results indicate that the optimized asymmetric supercapacitor has intriguing performances with a maximum energy density of 34.7 Wh/kg and power density of 5.6 k W/kg. A good electrochemical stability with 93% specific capacitance retained was demonstrated after consecutive 2000 cycle numbers.The carbon cloth coated Co/Al LDHs nanosheets(CC@Co/Al LDHs) as anode material was prepare by an easy hydrothermal method. Graphene was adhered on carbon cloth by self-assembly without using binding agent, which was used as cathode. An asymmetric supercapacitor(ASC) with a sandwich structure is designed by using the anode and cathode. The experimental results indicated that the ASC have a superior electrochemical energy storage performance(0.61 m Wh/cm3).