NEGATIVE ELECTRODE MATERIAL FOR LITHIUM ION SECONDARY BATTERY, METHOD FOR MANUFACTURING SAME, NEGATIVE ELECTRODE FOR LITHIUM ION SECONDARY BATTERY, AND LITHIUM ION SECONDARY BATTERY

摘要

The invention provides a negative electrode material for a lithium ion secondary battery, including a composite particle of a first particle containing a carbonic substance A and a second particle containing silicon, which are combined with a carbonic substance B, wherein, when a cross-section of the composite particle is observed with respect to: the content of silicon atom in a core region in a circle having a center thereof on the midpoint of the major axis, which constitutes the maximum length, and having a radius of 1/8 of the length of the minor axis orthogonally intersecting the major axis at the midpoint thereof, and the content of silicon atom in a rim region which extends from a circumference of the composite particle to a depth of 1/8 of the length of the minor axis, the ratio of the content in the rim region to the content in the core region is 2 or higher. A production method, and a negative electrode for a lithium ion secondary battery containing the negative electrode material, as well as a lithium ion secondary battery are provided.