Patent ID: 7041415

Claim:
A method for making a negative electrode component used in a nonaqueous secondary battery comprising the step of annealing natural graphite having a rhombic structure at a temperature of at least 2,000° C. to produce a negative electrode comprising a negative electrode comprising a carbonaceous material in which the ratio RG=Gs/Gb of the degree of graphitization Gs of the carbonaceous material, determined by a surface-enhanced Raman spectrum, to the degree of graphitization Gb, determined by a Raman spectrum measured using argon laser light, is at least 4.5, based on the following conditions: 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 Raman spectrum which is measured using 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 Raman spectrum which is measured using 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 surface-enhanced Raman spectrum which is measured using 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 carbonaceous material; and Hsb is the height of a peak lying in a range of 1,350 cm −1 to 1,400 cm −1 in a surface-enhanced Raman spectrum which is measured using 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 carbonaceous material.