A battery capable of reducing swelling is provided. A battery includes a cathode, an anode and an electrolyte. The anode includes a coating containing a SO3-containing compound, and the electrolyte contains an electrolyte salt having reduction power. Therefore, on the surface of the anode, the SO3-containing compound is preferentially reduced and decomposed to become a sulfur-containing compound. In the result, decomposition reaction of the electrolyte is prevented.