In the active material of a lithium-ion secondary battery, electrons and lithium-ions react at the same time. The fact that the active material can transfer electrons with a small reaction overvoltage leads to a reduction in the internal resistance of the battery. Therefore, when the electrical resistance was measured by changing the electrode material in contact with the active material, it was found that the electrical resistance of the active material was reduced depend on the carbon materials make contact with the active material.