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 the negative electrode active material particles have a maximum peak position by a Raman spectrum of more than 460 cm−1 and less than 500 cm−1, and
• wherein the negative electrode active material particles have a peak area ratio C/D according to the X-ray diffraction analysis method of less than 45.99 (C is an area of a Si peak positioned at 28.4±0.3°, and D is an area of a Li2Si2O5 peak positioned at 24.9±0.3° in the X-ray diffraction analysis).

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 the negative electrode active material particles have a maximum peak position by a Raman spectrum of more than 460 cm−1 and less than 500 cm−1, and
• wherein the negative electrode active material particles have a peak area ratio C/E according to the X-ray diffraction analysis method of less than 8.75 (C is an area of a Si peak positioned at 28.4±0.3°, and E is an area of a Li2SiO3 peak positioned at 26.9±0.3° in the X-ray diffraction analysis).