Toyo Tanso Co., Ltd.

Kazuhito Hoshi

Tetsuro Tojo

Toshiaki Sogabe

Naoto Ohta

Katsuhide Nagaoka

Hidehiko Nozaki

The invention provides an anode material for lithium ion secondary battery using a coated graphite powder as a raw material, which is coated thermoplastic resin of a carbonization yield of &#x2266;20 wt % in a proportion of &#x2266;10 parts by weight the carbonized material per 100 parts by weight graphite powder. Coating with thermoplastic resin increases the accumulative pore volume by &#x2266;5%, relative to the uncoated powder, and results in pore sizes of 0.012-40 &#x3bc;m via mercury porosimeter method. Calculated with the BJH method as viewed from desorption isotherm, the coated graphite powder has a mesopore volume &#x2266;0.01 cc/g or &#x2266;60% of the pore volume of the uncoated graphite powder. This coated powder also has an average particle size ranging from 10-50 &#x3bc;m measured by a laser-scattering-particle-size-distribution measuring device, and a standard deviation to the average particle size (&#x3c3;/D) ratio of &#x2266;0.02.

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Kagawa, Japan

Kazuhito Hoshi