| 摘要 |
[Problem] To provide a means for improving cycle durability of an electrical device such as a lithium-ion secondary cell. [Solution] A negative electrode active material that comprises a silicon-containing alloy having a composition represented by chemical formula (I): SixSnyMzAa (where A represents unavoidable impurities, M represents one or more transition metal elements, and x, y, z, and a represent values in mol%, such that 0 < x < 100, 0 < y < 100, 0 < z < 100, 0 ≤ a < 0.5, and x + y + z + a = 100), and that has a size of 10 nm or less, which size is obtained by performing a Fourier transform process from a lattice image of the silicon-containing alloy obtained using a transmission electron microscope, to obtain a diffraction pattern, performing an inverse Fourier transform process of a diffraction ring section present in a width of 0.7-1.0 within the diffraction pattern, where the distance between Si regular tetrahedrons in the diffraction image is assigned a value of 1.0, and from the Fourier image so obtained, taking the average value of the long-axis diameters of areas at five points of maximum long-axis diameter among areas having a periodic array, is used in an electrical device. |
