A method for making lithium ion battery is provided. A cathode material layer and an anode material layer are provided. A cathode current collector is formed on a surface of the cathode material layer to obtain a cathode electrode. The cathode current collector includes a graphene layer and a carbon nanotube layer stacked with the graphene layer. An anode current collector is formed on a surface of the anode material layer to obtain an anode electrode. A separator is applied between the cathode electrode and the anode electrode thereby forming a battery cell. At least one battery cell is encapsulated in an external encapsulating shell. An electrolyte solution is injected into the external encapsulating shell.