Carbon materials for negative electrode of secondary battery and manufacturing process

Abstract

A carbon material for negative electrode of a secondary battery, in particular lithium-ion secondary battery, is prepared by pyrolysis in an inert gas atmosphere or in a vacuum of a composite resin obtained by dissolving pitch in a pitch-soluble resin such as a nobolac phenol resin as it is, or a resin solidified by curing treatment in a state in which the above composite resin is dispersed in a resin solidified by curing treatment or in an uncured resin having a phenol hydroxyl radical such as resol type phenol resin, followed by pulverization in an inert gas, and further heat treatment in an inert gas atmosphere or in a vacuum. Also, a negative electrode material with which irreversible capacity is small, initial discharge capacity is large, and capacity decrease due to cycles is small can be provided by pyrolyzing in an inert gas atmosphere or in a vacuum powder of a resin such as a resol type phenol resin the primary chain of which containing an aromatic compound, or pyrolyzing in an inert gas atmosphere or in a vacuum in a first step, followed by heat treatment in a vacuum in a second step. By employing these negative electrode materials, it is possible to achieve a higher capacity in lithium-ion secondary batteries.