An ion-conducting material, a core-shell structure containing the ion-conducting material, an electrode prepared with the core-shell structure and a metal-ion battery employing the electrode are provided. The core-shell structure includes a core particle and an organic-inorganic composite layer formed on the surface of the core particle for encapsulating the core particle. The core particle includes lithium cobalt oxide, lithium nickel cobalt oxide, lithium nickel cobalt manganese oxide, or lithium nickel cobalt aluminum oxide. Also, the organic-inorganic composite layer includes nitrogen-containing hyperbranched polymer and an ion-conducting material. The ion-conducting material is a lithium-containing linear polymer or a modified Prussian blue, wherein the modified Prussian blue has an ion-conducting group and the lithium-containing linear polymer has an ion-conducting segment.