| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a sodium secondary battery having better cycle characteristics than the conventional one. <P>SOLUTION: The sodium secondary battery comprises a positive electrode containing a composite metal oxide, a negative electrode containing a carbon material capable of absorbing and releasing sodium ions, and an electrolyte. The composite metal oxide contains Na and M<SP>1</SP>, where M<SP>1</SP>represents two or more elements selected from the group comprising Mn, Fe, Co, and Ni, has a Na:M<SP>1</SP>molar ratio of a:1 wherein a is a value in a range of more than 0.5 and less than 1. The sodium secondary battery further has a separator. The separator has a laminated porous film formed by laminating a heat-resistant resin-containing heat-resistant porous layer and a thermoplastic resin-containing porous film. <P>COPYRIGHT: (C)2010,JPO&INPIT |
