Graphite material for negative electrode of lithium-ion secondary battery, lithium-ion secondary battery including the graphite material, and method of manufacturing graphite material for lithium-ion secondary battery

A method of manufacturing a graphite material for a negative electrode of a lithium-ion secondary battery, the method comprising:

• processing non-needle petroleum coke to have an average particle size ranging from 3 μm to 20 μm, both inclusive by pulverization and classification, the non-needle petroleum coke containing an optically isotropic structure at 75% or higher, transition metals at a total content ranging from 1000 ppm to 2500 ppm, both inclusive, and nitrogen at a content ranging from 1 wt % to 4 wt %, both inclusive;
• and
• graphitizing the processed non-needle petroleum coke at a temperature ranging from 2300° C. to 2900° C., both inclusive.