Abstract: Boron-substituted graphite, which contains N-bonded boron atoms in a small proportion relative to whole substituted boron atoms, is produced by heating a feed fine particulate mixture of an infusibilized carbonaceous material and a boron compound such that the carbonaceous material is carbonized into a carbon structure, raising a temperature of the resulting heated fine particulate mixture promptly to a graphitization treatment temperature in an inert atmosphere unreactive with boron, retaining the graphitization treatment temperature for a time sufficient to allow graphitization of the carbon structure to proceed to a desired extent, and then quickly cooling the resulting graphitized mixture. The boron-substituted graphite is useful as a negative electrode in a lithium-ion secondary battery.

Abstract: A process is provided for the production of a carbonaceous material. The process comprises the following steps: subjecting a vacuum distillation residual pitch to heat treatment until the content of quinoline-insoluble components thereof becomes 50 to 85 wt. %, whereby the pitch is converted into a mesophase pitch; grinding the thus-obtained mesophase pitch into fine particles having an aspect ratio not greater than 2; subjecting the thus-ground product to oxidation treatment; and subjecting the thus-oxidized product to carbonization or graphitization treatment. A lithium ion secondary battery comprises a negative pole made of the carbonaceous material.