| 摘要 |
PROBLEM TO BE SOLVED: To provide a battery long in cycle life by providing an electrolyte holding portion at a part other than the parts where a positive electrode faces a negative electrode, in a battery element comprising a winding body where a band-shaped positive electrode and a band-shaped negative electrode are wound through a separator. SOLUTION: In this secondary battery 1, a battery element 3 is stored in a cylindrical battery can 2. The battery element 3 comprises a band-shaped positive electrode 4 mainly containing lithium manganate, a band-shaped negative electrode 5 mainly containing a carbon material capable of doping or de- doping lithium, and band-shaped separators 6, 7, the positive electrode 4 and the negative electrode 5 are wound in a state that they are laminated through the separators 6, 7. An electrolyte-holding portion 10 is formed by forming a part of only separators 6, 7 in the tip part or the final part of the winding body of the battery element 3, or providing a porous body for holding electrolyte in a portion other than a power generation element. Hole volume of the battery element 3 is preferably 10-50% of total hole volume in an electrode group where the positive electrode 4 faces the negative electrode 5. |
