The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 10, 2012
Filed:
Nov. 08, 2007
Kenta Ishii, Tokyo, JP;
Kenta Ishii, Tokyo, JP;
Tokai Carbon Co., Ltd., Tokyo, JP;
Abstract
A negative electrode material for lithium ion secondary batteries includes core-shell composite particles prepared by covering the surface of a graphite powder with an amorphous carbon powder via a carbide of binder pitch, the graphite powder having an average particle diameter of 5 to 30 μm and an average lattice spacing d(002) of less than 0.3360 nm, and the amorphous carbon powder having an average particle diameter of 0.05 to 2 μm and an average lattice spacing d(002) of 0.3360 nm or more. A method to produce the negative electrode material includes mixing a graphite powder with pitch having a softening point of 70 to 250° C., adding an amorphous carbon powder to the resulting product, kneading the mixture while applying a mechanical impact to soften the pitch and carbonizing the pitch by heat treatment of the mixture at 750 to 2250° C. in a non-oxidizing atmosphere.