A metal-ion battery is provided. The metal-ion battery includes a positive electrode, a negative electrode, a separating structure, and an electrolyte, wherein the positive electrode and the negative electrode are separated by the separating structure, and the electrolyte composition is disposed between the positive electrode and the negative electrode. The separating structure includes a first separator, a second separator, and a dielectric layer, wherein the dielectric layer is disposed between the first separator and the second separator. The dielectric layer consists of a dielectric material, and the dielectric material has a dielectric constant from 10 to 200.