Application Research Of Graphene As Anode Material For Lithium Ion Batteries

LTO/Graphene and F-graphene nanosheets were prepared to improve deficiency of LTO and graphene used as anode material for lithium ion batteries based on the unique property of graphene. The electrochemical performance of different samples was investigated. The innovation lies in:1) Based on the unique2D nanostructure and excellent electrical conductivity of graphene, rate performance of LTO is improved by in-situ growing LTO nanoparticles on the surface of graphene sheets, effectively solving the low electrical conductivity and coacervate problem of LTO.2) F-graphene with a high fluorine content (49.7%) was prepared with liquid exfoliation method using F-graphite as raw material. The capacity of graphene and diffusion rate of Li+are improved by the collaborative mechanism of lithium storage and the unique2D nanostructure of F-graphene. Based on control of microstructure and surface chemical properties of LTO/Graphene nanocomposite and F-graphene, electrochemical performance of different samples were investigated. The main results are as follows.1) LTO nanoparticles prepared with hydrothermal method are distributed on the surface of the graphene intensively and evenly.The thickness of the graphene is about5nm, the size of LTO nanoparticles is about20nm.2) In-situ growth of LTO on the surface of graphene avoids the coacervate of LTO and provides a larger contact area for electrolyte and electrode. The reversible capacity and capacity retention of LTO/graphene nanocomposite material are159mAh/g and90.4%after100cycles, higher than pure LTO(95mAh/g,77.8%). Its reversible capacity at2A/g matains at151.6mAh/g, higher than LTO(24.8mAh/g).3) F-graphene prepared with liquid exfoliation method has a fluorine content of49.7%. The resulted material is2D nanostructure with thickness of4nm, width of1～3μm. Every fluorine atom is combined with a C atom.4) F-graphene has high fluorine content and collaborative lithium storage mechanism, improving its discharge capacity and cyclic performance. The capacity of F-graphene after50cycles at50mA/g and2A/g are793mAh/g and200.3mAh/g, respectively. After50cycles at50mA/g, the capacity of F-graphene composite with40%graphene is910mAh/g.