Fabrication Of Graphene And Its Application In Lithium Ion Batteries

Graphene, a new carbon material with two-dimensional crystal structure, has excellent physical and chemical properties. Lithium ion batteries, with advantages like high energy density, long cycle life, no memory effect, are one of the most mainstream energy storage devices. Graphene can be directly used as anode material for lithium ion batteris. In addition, graphene can be combined with cathode materials of lithium ion batteris, especially the LiFePO4, to improve the transport capacity of electrons and ions in the cathode materials.Based on the natural flake graphite as raw materials, graphene powder was fabricated by the thermal expansion stripping method and graphene paper material was prepared by the thermal reduction method, whose electrochemical performances were respectively studied as anode materials in lithium ion batteris. The results indicated that graphene powder was graphene with about2layers of worm-like folds. Under0.2C charge and discharge rate, its reversible capacity stabilized at about780mAh/g, and stabilized at about520mAh/g under0.5C rate. The prepared graphene paper material was holistic layer-shape structure, whose reversible capacity stabilized at about580mAh/g at a current density of50mA/g. Using mechanical mixing method and thermal reduction method, the LiFePO4/graphene composites were prepared and their electrochemical performances were studied as cathode material of lithium ion batteris. Results showed that the prepared LiFePO4/graphene composites compounded in good condition, in which graphene was coated on the surface of LiFePO4particles, and the graphene could connect with the particles. The LiFePO4/graphene composites exhibited a capability of116mAh/g under2C rate. Totally, there are38pieces of figures,4sheets of stables and123pieces of references.