A metal-ion battery is provided. The metal-ion secondary battery includes a positive electrode, a first negative electrode, a first separator, a second negative electrode, a second separator, and a control element, wherein the first separator is disposed between the positive electrode and the first negative electrode, and the second separator is disposed between the first negative electrode and the second negative electrode. Furthermore, the control element is coupled to the first negative electrode and the second negative electrode, wherein the control element determines whether to electrically connect the first negative electrode to the second negative electrode.