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Nano-structures on the surface of graphite based carbon particles have been investigated by means of high resolution transmission electron microscopy. The surfaces consist of “closed-edge” structures in a similar manner as carbon nano-tube. That is, they are composed of coaxial carbon tubes consisting of adequate coupling of graphite layer edges. These graphite particles are chemically stable and, therefore, applicable for lithium-ion secondary battery anodes. Molecular dynamics simulations based on the Tersoff potential reveal that the vibrations of the graphite layers at the free edges play an important role in the formation of the closed-edge structures. In lithium-ion secondary batteries, Li ions can intrude into bulk carbon anodes through these closed-edge structures. In order to clarify this intrusion mechanism, we have studied the barrier potentials of Li intrusion through these closed edges using the first-principles cluster calculations. From electrochemical measurements, the carbon anodes compos...

We report microstructures on the surface of graphite particles found in practicable carbon anodes by means of high-resolution transmission electron microscopy. The surfaces consist of “closed-edge” structures constructed in a similar manner as carbon nano-tube. We have also investigated the formation mechanism of these nano-structures using molecular dynamics simulations based on the Tersoff potential. From electrochemical measurements, the carbon anodes composed of these “closed-edge” structures show actually high battery performance with a large discharge capacity and a small irreversible capacity.

Cathodes composed of layered transition metal oxides LiMO2 (M = Co, Ni) and spinel manganese oxide LiMn2O4, carbon anodes, and nonaqueous electrolyte solutions have been investigated with the aim of achieving higher energy density. The lithium-ion rechargeable cell using the LiCoO2 cathode and the propylene carbonate(PC)-diethyl carbonate (DEC)/ LiPF6 electrolyte solution exhibits excellent characteristics. Furthermore, non-graphitizable carbon such as polyfurfuryl alcohol derived carbon has larger capacity and better cycleability than graphitizable carbon such as coke.