| 摘要 |
The present invention is a method for producing a negative electrode material for nonaqueous electrolyte secondary batteries, which comprises: a step for preparing base powder particles containing silicon; a step for measuring the volume average particle diameter of the prepared base powder particles by means of particle size distribution measurement using a laser diffraction method; a step for determining the circularities of a set of 5,000 or more particles randomly chosen from the base powder particles; a step for selecting base powder particles that are characterized in that the volume average particle diameter thereof is 0.5-20 μm, the average of the circularities of a set of 5,000 or more particles randomly chosen therefrom is 0.93 or more, and the number ratio of particles having a circularity of 0.85 or less is 5% or less; and a step for covering the surfaces of the thus-selected base powder particles with a carbon coating film. Consequently, there can be provided: a negative electrode material for nonaqueous electrolyte secondary batteries, which exhibits excellent cycle characteristics, while maintaining advantages of a material that contains silicon; a method for producing the negative electrode material for nonaqueous electrolyte secondary batteries; and a lithium ion secondary battery. |
