Electronic Properties of New Nano-Carbon Materials and its Application to High Capacity Li-ion Battery

Theoretical study of Li-doped nano-size PAHsThe interactions between nano-size PAHs(Polycyclic Aromatic Hydrocarbon)and Li are described by the quantum chemical method in order to clarify the Li storage mechanism in PAHs used in Li ion rechargeable batteries.The interaction of Li atoms with PAH layers proceeds preferentially up to the C_6Li configuration，followed by the adsorption of Li atoms on the surface and/or edge of the PAH accompanied with the deformation of carbon sheet。The characteristic vibronic interactions are also discussed in the negatively and positively charged PAH.The possibility of the fairly large interaction between H_2molecule and Li-doped PAH has been clarified.Preparation of PAHsThe PAHs were obtained by heat reaction of pitches in a nitrogen atmosphere at550°C或650°C for 4hrs。A large quantity of yellow vapor was produced around 350°C.The yield of the PAHs at 550℃和650℃was the same value of 43.5%.Properties of PAHsThe lattice images of the PAHs were observed by transmission electron microscope.The(002)layer distance and the crystallize size of the pitches were measured by XRD method。The crystallize size of c-axe was 3.2 nm，this value corresponds with about10layers of(002)plane.These results were reported in detail in“Synthetic metals，145(2004)31.Li ion battery using PAHs as an electrodeLi ion secondary battery cells were compounded using PAHs as activated materials of electrode.The charge and discharge characteristics of the cell using metal Li as counter electrode were measured.The charge and discharge capacity of the battery cell was 850 mAh/g and 520mAh/g，respectively.

Theoretical study of Li-doped nano-size PAHsThe interactions between nano-size PAHs (Polycyclic aromatic hydrocarbon ) and Li are described by the quantum chemical method in order to clarify the Li storage mechanism in PAHs used in Li ion rechargeable batteries. The interaction of Li atoms with PAH layers proceeds preferentially up to the C_6Li configuration, followed by the adsorption of Li atoms on the surface and/or edge of the PAH accompanied with the deformation of carbon sheet. The characteristic vibronic interactions are also discussed in the negatively and positively charged PAH. The possibility of the fairly large interaction between H_2 molecule and Li-doped PAH has been clarified.Preparation of PAHsThe PAHs were obtained by heat reaction of pitches in a nitrogen atmosphere at 550゜C or 650゜C for 4hrs. A large quantity of yellow vapor was produced around 350゜C. The yield of the PAHs at 550℃ and 650℃ was the same value of 43.5%.Properties of PAHsThe lattice images of the PAHs were observed by transmission electron microscope. The (002) layer distance and the crystallize size of the pitches were measured by XRD method. The crystallize size of c-axe was 3.2nm, this value corresponds with about 10 layers of (002) plane. These results were reported in detail in "Synthetic metals, 145(2004)31.Li ion battery using PAHs as an electrodeLi ion secondary battery cells were compounded using PAHs as activated materials of electrode. The charge and discharge characteristics of the cell using metal Li as counter electrode were measured. The charge and discharge capacity of the battery cell was 850 mAh/g and 520 mAh/g, respectively.