SODIUM RECHARGEABLE BATTERY

摘要

The present invention provides a sodium secondary battery having a superior cycling performance as compared with conventional techniques. A sodium secondary battery of the present invention comprises a positive electrode comprising a mixed metal oxide which comprises Na and M 1 wherein M 1 represents two or more elements selected from the group consisting of Mn, Fe, Co and Ni, with an Na:M 1 molar ratio being a:1 wherein a is a value falling within the range of more than 0.5 and less than 1, a negative electrode comprising a carbonaceous material capable of storing and releasing Na ions, and an electrolyte. Further, the sodium secondary battery of the present invention may comprise a separator, and the separator may be a separator comprising a porous laminated film in which a heat-resistant porous layer comprising a heat-resistant resin and a porous film comprising a thermoplastic resin are stacked each other.