| 摘要 |
PROBLEM TO BE SOLVED: To provide a secondary battery, having Ion internal resistance and capable of large- current discharge by providing a current collecting plate having a diameter smaller than that of an electrode group, by forming lead parts of a positive and negative electrodes in the peripheral part of the end part of the electrode group by projecting them from the end part, and by welding the lead parts to the current collecting plate in a form bent toward the current collecting plate. SOLUTION: Each lower end part 4B of a negative electrode 4 is shifted downward, rolled and projected from a positive electrode 2, and a current collecting plate 6b is welded to the projecting part and thus electrically connected to the negative electrode 4. Similarly, each upper end part 2A of the positive electrode is projected from the negative electrode 4 and welded to a current collecting plate 6a. The diameter of the current collecting plate 6a is smaller than that of an electrode group 5, so that the peripheral part of the positive electrode 2 is exposed. A plurality of lead parts 2L projected from the upper end parts 2A are formed in the peripheral part, and the lead parts 2L are welded to the current collecting plate 6a by bending them toward the current collecting plate 6a. A connection area is increased, as compared with the case in which the peripheral part of the upper end parts 2A are directly abutted on the current collecting plate 6a, and welding heat is easy to outflow, and welding defects are reduced. Likewise, lead parts 4L are formed on the lower end parts 4B of the negative electrode 4.
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