The invention discloses safe modified
graphite, which is characterized in that the
graphite is a
graphite negative
electrode material coated by NTC at normal temperature and belongs to the field of
lithium battery negative
electrode materials. The preparation method comprises the steps of firstly, mixing a
mixed solution of a normal-temperature NTC
raw material containing Zn, Cd, Ga, In, Mn, Fe, Mg, Cu, Co, Ti, Ni, Cr, Si or Be elements with a dispersion solution of graphite, and then
coating through
spray drying and scattering procedures to form a precursor of normal-temperature NTC materialcoated graphite; placing the precursor in an
atmosphere furnace for high-temperature
calcination; and finally, mixing, sieving and demagnetizing to obtain the NTC-coated graphite negative
electrode material. According to the method disclosed by the invention, the characteristics of
high resistivity at normal temperature and low resistivity at high temperature of the normal-temperature NTC materialare utilized, so that the prepared graphite is relatively low in activity at a low temperature or normal temperature and shows normal activity at a high temperature. If the graphite negative
electrode material is used in a battery with a heating function, low-temperature and normal-temperature
low activity can be achieved, the graphite negative
electrode material shows normal activity when the battery is heated, and meanwhile, the graphite negative
electrode material has better safety and
cycling stability than conventional graphite at a high temperature.