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

A negative-electrode active material for a non-aqueous electrolyte secondary battery, comprising:

• a base particle, which includes
• a lithium silicate phase represented by Li2zSiO(2+z) {0<z<2} including Li2Si2O5 and
• silicon particles dispersed in the lithium silicate phase,
• wherein a symmetry determined by an image analysis of a backscattered electron image of a cross section of the base particle is 1.5 or less, and
• the symmetry refers to a ratio (b/a) of a half width at half maximum b of a peak on a high-gray-scale side to a half width at half maximum a of the peak on a low-gray-scale side in a histogram of color distinction based on 256 gray levels for each pixel of the backscattered electron image,
• wherein a half-width of a diffraction peak attributed to a (111) plane in an XRD pattern obtained by XRD measurement of the Li2Si2O5 lithium silicate phase is in a range from 0.431° to 0.55°,
• wherein the negative-electrode active material for a non-aqueous electrolyte secondary battery after charging and discharging contains no Li4SiO4.