Patent ID: 7435511

Claim:
A nickel-metal hydride storage battery comprising a spirally wound electrode group, said electrode group comprising: (a) a positive electrode comprising an active material layer containing nickel hydroxide and a positive electrode core material; (b) a negative electrode comprising an active material layer containing a hydrogen storage alloy and a negative electrode core material; and (c) a separator, said positive and negative electrodes being wound with said separator interposed therebetween, wherein said separator comprises a hydrophilicity-imparted non-woven fabric comprising polyolefin or polyamide and has a thickness of 0.04 to 0 06 mm, said positive electrode has a thickness of 0.1 to 0.4 mm, said negative electrode has a thickness of 0.1 to 0.228 mm, the total thickness of the three layers of said positive electrode, said separator and said negative electrode is 0.24 to 0.708 mm, the percentage occupied by the cross section “S p ” of said positive electrode in the transverse cross section “S” of said electrode group is not less than 40%, the percentage occupied by the cross section “S s ” of said separator in the transverse cross section “S” of said electrode group is not greater than 25%, the battery further comprising a battery case for containing said electrode group, wherein the length of said positive electrode is not less than 5 times and not more than 10 times the inner perimeter “L” in the transverse cross section of the battery case.