Carbon powder suitable as a negative electrode material for nonaqueous secondary batteries

摘要

Carbon powder having low temperature calcined carbon derived from pitch adhered to a portion of the surface of natural graphite powder is obtained by solids mixing of natural graphite powder and pitch powder as a carbon precursor followed by heat treatment at 900-1500° C. to carbonize the pitch. The amount of pitch powder is such that the ratio V2/V1 of the pore volume V2 of pores having a diameter of 50-200 nm to the pore volume V1 of pores having a diameter of 2-50 nm in a pore size distribution curve obtained by analysis of the nitrogen desorption isotherm of the resulting carbon powder by the BJH method is at least 1. This carbon powder can be used as a negative electrode material for a nonaqueous secondary battery able to operate at low temperatures.