Negative electrode active material for non-aqueous electrolyte secondary batteries, and non-aqueous electrolyte secondary battery

Abstract

The initial charge/discharge efficiency and cycle characteristics of a non-aqueous electrolyte secondary battery that contains a silicon material as a negative-electrode active material are improved. A negative-electrode active material particle (10) according to an embodiment contains a base particle (13), which includes a lithium silicate phase (11) represented by Li2zSiO(2+z) {0<z<2} and silicon particles (12) dispersed in the lithium silicate phase (11). The symmetry determined by an image analysis of a backscattered electron image of a cross section of the base particle (13) is 1.5 or less. The symmetry refers to the ratio (b/a) of the half width at half maximum b of a peak on the high-gray-scale side to the half width at half maximum a of the peak on the low-gray-scale side in a histogram of color distinction based on 256 gray levels for each pixel of the backscattered electron image.

Dependencies are inferred from the claim text.