Patent ID: 6447957
Filing Date: 2002-09-10
Classification: H01M

Abstract:
A current collector for a secondary battery, comprising a metal foil, wherein:said metal foil has a thickness of at least 5 &mgr;m and at most 200 &mgr;m; said metal foil contains at least one of aluminum and copper; said metal foil has therein a plurality of throughholes including first throughholes and second throughholes; said plurality of throughholes has a total hole area corresponding to a hole area ratio of at least 40% relative to a total area of said metal foil; each one of said first throughholes has a largest dimension of at least 1.55 mm and not more than 5.0 mm; each one of said first throughholes has a first peripheral shape including at least four substantially straight sides; at least respectively a first pair of said substantially straight sides adjoin each other to form a respective first acute corner of said first peripheral shape and respectively extend along two lines that intersect each other to form an acute angle spanning said first acute corner; and each one of said second throughholes has a second peripheral shape that is different from said first peripheral shape of said first throughholes.