A method for lithiation of an electrode includes providing an electrode to be lithiated, providing a piece of lithium metal with predetermined weight attached to a conductive material, attaching the conductive material to a current collector of the electrode to be lithiated or to a metal tab connected to or from the electrode to be lithiated, placing the electrode to be lithiated, the piece of lithium, and the conductive material in a container, and filling the container with an electrolyte containing a lithium salt.