Mitsubishi Chemical Corporation

Taisuke Nose

Hideharu Sato

Shunsuke Yamada

Keita Yamaguchi

To provide a negative electrode material capable of giving a lithium ion secondary battery that is sufficiently small in the charge/discharge irreversible capacity observed at the initial cycle stage, has excellent high-temperature storage characteristics, and reduced in the gas generation at the initial cycle stage as well as during high-temperature storage. A carbon material for lithium ion secondary battery, wherein the surface functional group amount O/C value represented by the following formula 1 is from 1 to 4% and the sum (Cl/C+S/C) of the surface functional group amount Cl/C value represented by the following formula 2 and the surface functional group amount S/C value represented by the following formula 3 is from 0.05 to 0.5%:O/C value (%)=O atom concentration determined based on the peak area of the spectrum of O1s in X-ray photoelectron spectroscopy (XPS) analysis/C atom concentration determined based on the peak area of the spectrum of C1s in XPS analysis&#xd7;100&#x2003;&#x2003;Formula 1:Cl/C value (%)=Cl atom concentration determined based on the peak area of the spectrum of Cl2p in XPS analysis/C atom concentration determined based on the peak area of the spectrum of C1s in XPS analysis&#xd7;100&#x2003;&#x2003;Formula 2:S/C value (%)=Satom concentration based on the peak area of the peak near 165 eV in the spectrum corresponding to S2p in XPS analysis/C atom concentration determined based on the peak area of the spectrum of C1s in XPS analysis&#xd7;100&#x2003;&#x2003;Formula 3.

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Kagawa, Japan

Taisuke Nose