Composite particles, negative electrode mixture layer and lithium-ion secondary battery

Abstract

One embodiment of the present invention is composite particles containing silicon and carbon, which are characterized as follows. When the cross-sectional diameter and the silicon content rate of the composite particles are measured by cross-sectional SEM-EDS and composite particles having a cross-sectional diameter of half or less than the number average of the cross-sectional diameter are defined as small diameter composite particles, the proportion of the number of the small diameter composite particles in the number of the composite particles measured is 5% or more and 50% or less, the ratio of the average silicon content rate (% by mass) of particles other than the small diameter composite particles to the average silicon content rate (% by mass) of the small diameter composite particles is 0.90 or less, and the silicon content rate of the entire composite particles is 45% by mass or more.

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