An apparatus for inerting a space includes a metal-air battery, a feed channel for the introduction of air from an air source to the metal-air battery, and a discharge channel for the discharge of air from the metal-air battery to a volume of the space. A control unit controls an electrochemical reaction of the metal-air battery as a function of a fire situation within the space. A method for inerting a space, an inerting system, an inerting method and an aircraft or spacecraft are also provided.