scope of the present invention subsequently as shown in fig6 to 10 in the third step 130 the unit electrode plate 58 is cut using a cutting tool 64 such that both corner regions 58 c 58 c u2032 thereof are removed thus providing a tab junction 50 c on the blank region 581 in this embodiment both corner regions 58 c 58 c u2032 which are positioned at the opposite ends of the blank region 581 formed at a side of the unit electrode plate 58 are removed however the present invention is not limited thereto and the present invention may be applied to any case in which at least one corner of the unit electrode plate 58 is removed in fig6 9 there is shown only the cutting tool 64 for clarity of explanation the cutting tool 64 may be formed to have a shape corresponding to the corner regions 58 c 58 c u2032 the term u201c shape corresponding to the corner regions u201d denotes a shape in which the corner regions 58 c 58 c u2032 are cut away according to a previously defined pattern in this embodiment the cutting tool 64 has a planar rectangular shape in which the corner regions 58 c 58 c u2032 are cut away in rectangular shapes the cutting tool 64 may include cutting knifes therein so as to remove.