NOVELTY - Lithium ion battery comprises a battery shell, a battery group and an electrolyte.    USE - The lithium ion battery is useful for industrial and commercial applications.    ADVANTAGE - The battery increases the high temperature safety of the battery and the insulating coating has a certain penetrating ability of the lithium ion so as to increase the initial volume of the battery.    DETAILED DESCRIPTION - Lithium ion battery comprises a battery shell, a battery group and an electrolyte; the battery group and the electrolyte are sealed in the battery shell; the battery group includes an anode sheet, a cathode sheet and a separation film; the anode sheet includes an anode flow collector, an anode material layer attached on the surface of the anode flow collector and an anode tag attached with the surface on one end of the anode flow collector; the cathode sheet includes a cathode flow collector, a cathode material layer attached on the cathode flow collector and a cathode tag attached with the surface on one end of the cathode flow collector; the following areas of the battery are provided with insulating coating layers: (a) the area corresponding to the other surface of the anode sheet in the bonding area of the anode tag and the anode flow collector; and (b) the area corresponding to the other surface of the cathode tag and cathode flow collector and the area corresponding to the other surface of the cathode sheet in the cathode tag and cathode flow collector; the area of the insulating coating layer on the anode is smaller than that of the anode material layer; the area of the insulating coating layer on the cathode is smaller than that of the cathode material layer; and the insulating coating layer contains an inorganic oxide and bonding agent. An INDEPENDENT CLAIM is a preparation method of lithium ion battery comprising: attaching anode material and cathode material on two surfaces of the anode flow collector and the cathode flow collector, connecting the anode tag and cathode tag on the surface of one end of the anode flow collector and the surface of one end of the cathode flow collector, preparing the anode sheet and cathode sheet; setting the separation film between the anode sheet and the cathode sheet to roll into an electrode group; assembling the battery group to the battery shell and injecting the electrolyte, wherein the method also includes after connecting the tag and before preparing the electrode group, forming insulating coating layer in at least the following areas by the insulating material: (a) the area corresponding to the other surface of the anode sheet in the bonding area of the anode tag and the anode flow collector; and (b) the area corresponding to the other surface of the cathode tag and cathode flow collector and the area corresponding to the other surface of the cathode sheet in the cathode tag and cathode flow collector; the area of the insulating coating layer on the anode is smaller than that of the anode material layer; the area of the insulating coating layer on the cathode is smaller than that of the cathode material layer; the insulating coating layer contains an inorganic oxide and bonding agent.