FLUORIDE ION SECONDARY BATTERY

The present invention provides a fluoride ion secondary battery which has high initial charge/discharge efficiency, while starting with a charged state and having a high voltage. According to the present invention, a composite body is formed using, as negative electrode active materials, nanometer-sized aluminum particles and modified aluminum fluoride together with the other constituents of a negative electrode mixture, said modified aluminum fluoride having voids that are formed by deintercalation of fluoride ions; and a fluoride ion secondary battery is configured by combining a negative electrode, which uses this composite body, with a positive electrode that contains a specific substance as a positive electrode active material.