NEGATIVE ELECTRODE ACTIVE MATERIAL FOR SECONDARY BATTERY, AND SECONDARY BATTERY USING SAME

A negative electrode active material for a secondary battery includes composite particles. The composite particles include a lithium silicate phase and a silicon phase dispersed in the lithium silicate phase, wherein the silicon phase has lined portions in the lithium silicate phase, a maximum diameter Dand a minimum diameter Dof the lined portions satisfy 3≤D/D. The composite particles include a metal Me dispersed in the lithium silicate phase, and the metal Me is at least one selected from the group consisting of Fe, Pb, Zn, Sn, Cu, Ni, Cr, Zr, and Ti.