Graphene Based Electrode Using In Rechargeable Lithium Ion Batteries

ABSTRACT:Conventional carbon material (natural graphite) is a practical anode material used for Lithium ion batteries (LIBs), because of its low cost, safety, cycle stability and other characteristics. Graphite using in LIBs have disadvantage of low capacity and low discharge rate. And another anode material of LIBs is Nitride, Silicide Tin-based oxides or compounds. They have higher capacity and discharge rate than graphite. However, Nitride, Silicide, Tin-based oxides or compounds using in LIBs, the decisive problem of the anode materials is the large volume change during the Li ion insertion and extraction. The electrode structural stability and cost limited the use in LIBs. So the preparation of graphene(GNS) and modified graphene (graphene and fullerenes, carbon nanotubes composite, respectively) becomes necessary to overcome the insufficient of anode materials.Therefore, this paper made the following research:(1) GNS were prepared through the thermal exfoliation of OGS, which was synthesized by a modified Hummers’method. The structure of the pristine GNS was analyzed by atomic force microscope (AFM), scanning electron microscope (SEM), X-ray diffraction (XRD) and Raman spectroscopy.(2) Studied the electrochemical properties of GNS as an anode material for lithium ion batteries. Analyzed by specific capacity, cycles, coulombic efficiencyjetc. The results showed that the specific capacity of GNS is higher than graphite. The theoretical capacity of graphite is372mAh/g, the theoretical capacity of GNS is744mAh/g. GNS’s first average capacity is861.5mAh/g. The specific capacity of GNS was found to be280mAh/g after100cycles at2C;(3) Studied the electrochemical properties of GNS+C60as an anode material for lithium ion batteries. Analyzed by specific capacity, cycles, coulombic efficiency etc. The results showed that the specific capacity of GNS+C60is higher than GNS. The first specific capacity of GNS was found to be861.5mAh/g, and this was increased up to1026.6mAh/g by the incorporation of macromolecules of C60to the GNS. The specific capacity of GNS+C60was found to be301mAh/g after100cycles at2C. This is higher than280mAh/g of GNS under the same conditions. The coulomb efficiency of GNS was found to be97.7%, and this was increased up to97.9%by the incorporation of macromolecules of C60to the GNS.(4) Studied the electrochemical properties of GNS+CNT as an anode material for lithium ion batteries. Analyzed by specific capacity, cycles, coulombic efficiency etc. The results showed that the specific capacity of GNS+CNT is higher than GNS+C60-The first specific capacity of GNS+C60was found to be1026.6mAh/g, and this was increased up to1270.6mAh/g by the incorporation of macromolecules of CNT to the GNS. The specific capacity of GNS+CNT was found to be365mAh/g after100cycles at2C. This is higher than301mAh/g of GNS+C60under the same conditions. The coulomb efficiency of GNS+C60was found to be97.9%, and this was increased up to98.0%by the incorporation of macromolecules of CNT to the GNS.