NEGATIVE ELECTRODE ACTIVE MATERIAL, NEGATIVE ELECTRODE INCLUDING NEGATIVE ELECTRODE ACTIVE MATERIAL, AND SECONDARY BATTERY INCLUDING NEGATIVE ELECTRODE

A negative electrode active material including silicon-based active material particles each including a core including SiO, wherein 0≤x≤2, and a coating layer present on the core. Also, a negative electrode active material in which the coating layer is any one of a carbon coating layer or a polymer coating layer, and the coating layer includes a fluorinated material including at least one of an alkali metal or an alkaline earth metal.