NEGATIVE ELECTRODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY COMPRISING CARBON MATERIAL AND METAL OR METAL COMPOUND CAPABLE OF BEING ALLOYED WITH LITHIUM, AND PREPARATION METHOD THEREOF

摘要

PURPOSE: Provided are a negative electrode active material for a lithium secondary battery which acts as a mechanical/electrical matrix to the volume expansion of metals generated during the charging/discharging with lithium and is excellent in initial efficiency, reversible efficiency and lifetime characteristic, and its preparation method. CONSTITUTION: The negative electrode active material comprises a carbon material which can absorb and desorb lithium; and 10-80 wt% of a metal or metal compound particle which is dispersed inside the carbon material and can be alloyed with a lithium element and on the surface of which a metal oxide is formed. Preferably the metal or metal compound is represented by A_(1-x) B_x, wherein 0=x=0.9; A is at least one kind of metal selected from the group consisting of Sn, Si, Ag, Zn, Cd, Al, Ga, In, Ce, Pb, As, Bi and Sb; and B is at least one kind of element selected from the group consisting of Zr, Ti, Fe, Co, Ni, Cu, C, O, N and S. Preferably the active material has an average diameter of 10-100 micrometers; and is spherical or elliptical.