The application discloses a battery which comprises a case provided with an opening at one end and a hollow cavity, and an upper cover of the case at the opening of the case. An electrolyte is arranged in the hollow cavity, an electrolyte is arranged in the hollow cavity, and at least one first part and at least one second part are arranged at intervals in the electrolyte, wherein the electrolyte is a halate solution, and the first part is made of magnesium. The application further discloses a battery pack which comprises a battery and a box body. The battery and the battery pack thereof solve the technical problem that the present battery technique cannot realize simple structure, convenience of preparation, safe and environment-friendly use and low cost.