GRAPHITE MATERIAL FOR LITHIUM ION SECONDARY BATTERY NEGATIVE ELECTRODE, METHOD OF MANUFACTURING THE SAME, AND LITHIUM ION SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide a graphite material for a lithium ion secondary battery negative electrode which enables the suppression of the deterioration in capacity associated with the iteration of charge and discharge cycles, the storage of a battery in its charged condition, the floating charge, etc.

SOLUTION: Provided is a graphite material for a lithium ion secondary battery negative electrode which is characterized in: the size Lc(112) of a crystallite of the c-axial direction calculated from (112) diffraction line measured by X-ray powder diffraction is 4.0-30 nm; a spectrum originating from carbon which arises in an electron spin resonance spectroscopy by which measurement is conducted using X band is within a range of 3200-3400 gausses(G); the relative signal intensity ratio (I4.8K/I40K) of the signal intensity (I4.8K) of the spectrum measured at a temperature of 4.8K to the signal intensity (I40K) of the spectrum measured at a temperature of 40K is 1.5-3.0; and the line width ▵Hpp of the spectrum calculated from the primary differential spectrum at the temperature of 4.8K is 20-40 gausses(G).

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