Novel conglomeration graphite, secondary battery including same as anode active material, and method for producing conglomeration graphite

A method for producing conglomeration graphite, comprising steps of:

• (a) pulverizing flaky natural graphite and pitch, respectively (‘natural graphite and pitch pulverization step’);
• (b) mixing the natural graphite and the pitch respectively pulverized at the step (a) (‘natural graphite and pitch mixing step’);
• (c) further mixing a mixture of the step (b) with a solvent (‘solvent mixing step’);
• (d) preparing a conglomerated first graphite composite by conglomerating the mixture of the step (c) (‘conglomeration step’);
• (e) adding and mixing-coating additional pitch to the first graphite composite in which conglomeration of the step (d) is completed (‘additional pitch adding and mixing-coating step’);
• (f) preparing a second composite in which the additional pitch is coated on an outside of the conglomerated first graphite composite by completing additional mixing of the mixture of the step (e) (‘additional mixing completion step’);
• (g) performing a first heat treatment on the second composite of the step (f) (‘first heat treatment step’);
• and
• (h) after the first heat treatment of the step (g), cooling to room temperature and then performing a second heat treatment,
• wherein at the step (e), an amount of the additional pulverized pitch is determined such that the sum of the pulverized pitch of the step (a) and the additional pulverized pitch of the step (e) exceeds 25% by weight out of the total weight part of the sum of the pulverized natural graphite and pulverized pitch of the step (a) and the additional pulverized pitch,
• wherein at the step (g), the first heat treatment is performed under heat treatment conditions of 1,000° C. or more for 30 minutes or more, and
• wherein at the step (h), the second heat treatment is performed under heat treatment conditions of 2,000° C. or more for 30 minutes or more.