Patent ID: 9614216
Date: 2017-04-04
CPC Classifications: H01M,Y02E

Claim:
1. A negative electrode material for a lithium ion secondary battery, the material comprising a composite particle of a first particle comprising a carbonic substance A and a second particle comprising silicon atoms, the first particle and the second particle combined by a carbonic substance B different from the carbonic substance A, wherein the first particle comprises a graphite particle having pores formed by assembling or binding a plurality of flat-shaped particles in such a manner that orientation planes thereof are nonparallel to each other, and wherein, when a cross-section of the composite particle is observed with respect to: a content of the silicon atoms included in a core region in a circle, the circle having a center thereof on a midpoint of a major axis constituting a maximum length of the composite particle, and having a radius of ⅛ of the length of a minor axis that orthogonally intersects the major axis at the midpoint thereof, and a content of the silicon atoms in a rim region of the composite particle, which extends from a circumference of the composite particle to a depth of ⅛ of the length of the minor axis, a ratio of the content of the silicon atoms in the rim region to the content of the silicon atoms in the core region is 2 or higher.