Lithium-ion secondary battery and method of charging lithium-ion secondary battery

A lithium-ion secondary battery comprising:

• a positive electrode collector having a surface formed with a positive electrode active material layer containing a positive electrode active material;
• a negative electrode collector having a surface formed with a negative electrode active material layer containing a negative electrode active material;
• an electrically insulating porous separator;
• and
• an electrolyte containing a lithium salt and being in contact with the positive electrode active material layer, negative electrode active material layer, and separator;
• wherein the positive and negative electrode collectors are disposed such that the positive and negative electrode active material layers hold the separator therebetween;
• wherein the negative electrode active material is a carbon material having a graphite structure;
• wherein the amount of the carbon material supported by the negative electrode active material layer is 2.0 to 4.0 mg/cm2;
• and
• wherein the graphite structure in an X-ray diffraction pattern of the carbon material exhibits a peak intensity P101 of (101) plane and a peak intensity P100 of (100) plane having a ratio (P101/P100) of 2.0 to 2.8 therebetween.