Negative electrode active material for secondary battery and manufacturing method thereof

A negative electrode active material for a secondary battery, wherein the negative electrode active material comprises silicon-based primary particles,

• a particle size distribution of the silicon-based primary particles is 50 nm≤D10<80 nm, 80 nm≤D50 (median particle diameter)≤100 nm, and 105 nm<D90≤150 nm,
• the particle size distribution width (D90−D10)/D50 of the silicon-based primary particles is 1.0 or less,
• circularity of the silicon-based primary particles is in a range of 0.6 to 0.8, wherein the circularity is defined as:
• circularity
• =
• 2
• ⁢
• π
• ⁢
• A
• P
• where A is a projected area of the two-dimensionally projected silicon-based primary particles, and P is a perimeter of the two-dimensionally projected silicon-based primary particles, and
• wherein the silicon-based primary particles comprise a silicon particle core and a silicon oxide layer formed on the core.