| 摘要 |
PROBLEM TO BE SOLVED: To provide a long lifetime and excellent discharge characteristics by setting fiber density of the side of a separator opposite to a negative electrode lower than the fiber density of a side thereof opposite to a positive electrode so as to improve the oxygen gas absorbing capability of the negative electrode, and restricting the rise of the inner pressure of a battery. SOLUTION: A separator to be interposed between a positive electrode and a negative electrode is formed of non-woven fabric. The non-woven fabric is formed into the double structure, and fiber density of the non-woven fabric to be arranged in a side opposite to the negative electrode is set lower than that of the non-woven fabric to be arranged in a side opposite to the positive electrode. Or, the fiber density of the non-woven fabric is made in such a manner as to be come lower continuously from the surface opposite to the positive electrode to the surface opposite to the negative electrode. With this structure, since the oxygen gas to be generated in the positive electrode can be efficiently absorbed by the negative electrode, the rise of the inner pressure of a battery can be restrain, and the lifetime is prolonged, and discharge characteristics can be improved. |
