Patent ID: 7037623

Claim:
A method for making a negative electrode carbonaceous material comprising the steps of: (a) carbonizing a raw material, (b) heating the product of step (a) at a temperature of at most 200° , in the presence of an oxidizer; and (c) graphitizing the product of step (b), wherein a ratio RG=Gs/Gb of the product of step (c) is at least 4.5, wherein: Gb=Hbb/Hba ; and Gs=Hsb/Hsa ; wherein: Hba is the height of a peak lying in a range of 1,580 cm −1 to 1,620 cm −1 in a first Raman spectrum, said first Raman spectrum being measured by means of an argon laser Raman spectrometer of a wavelength of 514.5 nm and a wavelength resolution of 4 cm −1 ; Hbb is the height of a peak lying in a range of 1,350 cm−1 to 1,400 cm−1 in a second Raman spectrum, said second Raman spectrum being measured by means of an argon laser Raman spectrometer of a wavelength of 514.5 nm and a wavelength resolution of 4 cm −1 ; Hsa is the height of a peak lying in a range of 1,580 cm −1 to 1,620 cm −1 in a first surface-enhanced Raman spectrum, said first surface-enhanced Raman spectrum being measured by means of an argon laser Raman spectrometer of a wavelength of 514.5 nm and a wavelength resolution of 4 cm −1 when silver having a thickness of 10 nm is deposited on the product of step c.; and Hsb is the height of a peak lying in a range of 1,350 cm −1 to 1,400 cm −1 in a second surface-enhanced Raman spectrum, said second surface-enhanced Raman spectrum being measured by means of an argon laser Raman spectrometer of a wavelength of 514.5 nm and a wavelength resolution of 4 cm −1 when silver having a thickness of 10 nm is deposited on the product of step c.