LITHIUM ION SECONDARY BATTERY

A lithium ion secondary battery is provided. The lithium ion secondary battery includes an electrolytic tank having an accommodating space, a positive electrode disposed in the accommodating space, a negative electrode disposed in the accommodating space and spaced apart from the positive electrode, and an isolation film disposed between the positive electrode and the negative electrode. In the X-ray diffraction spectrum of a first surface of the electrolytic copper foil, a ratio of the diffraction peak intensity I(200) of the (200) crystal face of the first surface relative to the diffraction peak intensity I(111) of the (111) crystal face of the first surface is between 0.5 and 2.0. A ratio of the diffraction peak intensity I(200) of the (200) crystal face of a second surface relative to the diffraction peak intensity I(111) of the (111) crystal face of the second surface is between 0.5 and 2.0.