GRAPHITE-BASED NEGATIVE ELECTRODE ACTIVE MATERIAL, NEGATIVE ELECTRODE, AND LITHIUM ION SECONDARY BATTERY

摘要

This graphite-based negative electrode active material includes first graphite particles which are spherically formed; and second graphite particles having a lower roundness than the first graphite particles. The content of the second graphite particles is 1-30 mass% of the sum total of the first graphite particles and the second graphite particles. The ratio (D50/D5) of the median particle size (D50) of the first graphite particles to the particle size (D5) of the first graphite particles at 5 cumulative% in the cumulative distribution thereof is less than the ratio (D50/D5) of the median particle size (D50) of the second graphite particles to the particle size (D5) of the second graphite particles at 5 cumulative% in the cumulative distribution thereof. The saturated tap density of mixed particles obtained by mixing the first graphite particles and the second graphite particles is greater than both the saturated tap density of the first graphite particles and the saturated tap density of the second graphite particles.