Provided is a negative electrode material for a lithium-ion secondary battery having a sufficient strength capable of exerting a certain resistance to the applied pressure to maintain the electrolytic solution flow path and maintain the non-parallel orientation of the flat graphite constituting the graphite particle spherical aggregates when pressed during electrode formation while being deformed such that the graphite particle spherical aggregates reach a certain density or more, and thus capable of increasing the electrode density and improving discharge capacity and excellent in cycle characteristics.
A negative electrode material for a lithium-ion secondary battery contains a mass of graphite particle spherical aggregates in which a plurality of flat graphite particles are aggregated. The mass of the graphite particle spherical aggregates has an average circularity, D 90 /D 10 , and a crystallite size Lc (004) within a predetermined range, and the proportion of the graphite particle spherical aggregates in which the largest flat graphite particle observed on the outermost surface has a circle equivalent diameter of 2 µm to 12 µm in graphite particle spherical aggregates having a circle equivalent diameter of 10 µm or more when observed by SEM is 80% or more.