Preparation of high-crystallinity synthetic graphite from hard carbon-based carbon black

Hard carbon is difficult to prepare as high-crystallinity synthetic graphite even with graphitization (over 2400 °C), so only soft carbon has been used as a raw material for the preparation of synthetic graphite. Therefore, the selection of raw materials for synthetic graphite preparation is limited. In this study, synthetic graphite was prepared from hard carbon-based carbon black (HCCB) to overcome the issue of the limited selection of synthetic graphite raw materials. Synthetic graphite was prepared by a 3-step heat treatment from a mixture of HCCB and Si. SiC was synthesized from HCCB by a first heat treatment, and unreacted HCCB was removed through a second heat treatment. In a third heat treatment, synthetic graphite was prepared by removing Si from SiC. The prepared synthetic graphite had a high-crystallinity and few defects, and the powder electrical conductivity was approximately 22.7 times higher than that of graphitized HCCB. The introduced new method is expected to induce diversification of raw materials for the preparation of synthetic graphite, thereby solving the problems of the traditional preparation method.