Yoshikazu Yoshimoto

Rechargeable lithium battery based on pyrolytic carbon as a negative electrode

Abstract We have developed a new type of rechargeable lithium battery composed of a pyrolytic carbon as negative electrode, a metal oxide as positive electrode, and a nonaqueous electrolytic solution. The main feature of this battery is the use of a new pyrolytic carbon, obtained by chemical vapor deposition of hydrocarbon, as a lithium intercalation electrode. The pyrolytic carbon has a layered structure whose interplanar spacing is larger than that of graphite. The size of the crystallites is extremely small. Lithium can be electrochemically intercalated into this carbon electrode in a nonaqueous electrolytic solution such as LiClO 4 in propylene carbonate at room temperature. The electrode shows good reversibility and its coulombic efficiency is greater than 99%. The battery has a long cycle life and endures deep discharge.

Low temperature growth of pyrolytic carbon with well-ordered graphite structure by chemical vapour deposition methods

Abstract Carbon films with well-ordered graphite structure were successfully deposited on a quartz substrate by thermal decomposition of benzene gas at 1000°C. The improvement in the degree of preferred orientation to the substrate surface was verified by reflection high energy electron diffraction observations. Such good crystallinity of the films was shown to be responsible for high in-plane electrical conductivity ( σ | = 2.2 × 10 3 Ω -1 cm -1 ). Investigations concerning the film properties and their dependence on the deposition conditions will be described.

Method for the production of carbon films having an oriented graphite structure

A method for preparing pyrolytic carbon film having a highly ordered graphite structure which comprises introducing an aromatic compound not having a condensed ring, together with a carrier gas into a reaction chamber, thermally decomposing the aromatic compound at a temperature up to 1,000° C., and depositing the carbon film onto a single-crystalline substrate.

The Formation of Pyrolytic Carbon on a Nickel Sheet

Pyrolytic carbon films were deposited on nickel sheets by pyrolysis of benzene at 1000°C. The surface morphology and the degree of graphitization of the deposited carbon films depended on the benzen concentration of the supplied gas. A large amount of nickel was extruded from the nickel substrate to the surface of the carbon film at a certain concentration of benzene.

Electrochemical characterization of Li-intercalated pyrolytic graphite

Abstract A new type of Li-intercalated graphite C 9 Li as well as thermodynamic data have been obtained from the study of characteristics of electrochemical deintercalation for the Li-intercalated graphites made by vapor transport method.