Lithium-Doped Silicon-Based Oxide Negative Electrode Active Material, Method of Preparing the Same, and Negative Electrode and Secondary Battery Including the Same

A negative electrode active material comprising:

• negative electrode active material particles including a silicon oxide (SiOx, 0<x≤2) and at least one lithium silicate selected from Li2SiO3, Li2Si2O5, and Li4SiO4 in at least a part of the silicon oxide,
• wherein when a signal generated in a region of 200 to 600 cm−1 according to a Raman spectrum is subjected to deconvolution into three peaks, which are set to peak A, peak B, and peak C from lowest to highest of an absolute value of a wavenumber, the negative electrode active material particles satisfy the following Relation 1:
• 0.3≤D(=C′/B′−C″/B″)≤1.0 [Relation 1]
• wherein
• D is a difference value of a peak area ratio (C″/B″) from a peak intensity ratio (C′/B′),
• the peak intensity ratio (C′/B′) is a ratio of an intensity of the peak C to an intensity of the peak B, and
• the peak area ratio (C″/B″) is a ratio of an area of the peak C to an area of the peak B.