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

摘要

PROBLEM TO BE SOLVED: To provide a graphite material for the negative electrode of a lithium ion secondary battery, there a strength ratio I101/I100 of a plane 101 to a plane 100 is not less than 1.2 in X-ray diffraction measurement, and initial charging/ discharging efficiency and initial charging/discharging capacity, when soaked in electrolyte solution then charged at 30 to 50 degrees centigrade, are higher than those when soaked in electrolyte solution then charged at 25 degrees centigrade. SOLUTION: By using a graphite material for a negative electrode which contains a high ratio of graphite and has specific charging/discharging characteristic at high temperatures, a lithium ion secondary battery which shows high charging/discharging efficiency and has high discharging capacity after being charged or discharged especially at high temperatures can be provided.