NI-PLATED STEEL FOIL FOR NICKEL-HYDROGEN SECONDARY BATTERY CURRENT COLLECTOR, NICKEL-HYDROGEN SECONDARY BATTERY CURRENT COLLECTOR, AND NICKEL-HYDROGEN SECONDARY BATTERY

A high-strength steel foil for the positive and negative electrode current collectors of nickel-hydrogen secondary batteries which uses a light weight and economical steel foil and which is thin and strong and has excellent rust resistance and resistance to metal ion leaching. Also, a high-strength steel foil for the positive and negative electrode current collectors of nickel-hydrogen secondary batteries which has excellent elongation. The Ni-plated steel foil for hydrogen secondary battery current collectors comprises, by mass %, C: 0.0001 to 0.0200%, Si: 0.0001 to 0.0200%, Mn: 0.005 to 0.300%, P: 0.001 to 0.020%, S: 0.0001 to 0.0100%, Al: 0.0005 to 0.1000%, N: 0.0001 to 0.0040%, one or both of Ti and Nb: 0.800% or less respectively, and a balance of Fe and impurities. The Ni-plated steel foil has an Ni plating layer on both surfaces. The thickness of the Ni plating layer on both surfaces of the Ni-plated steel foil is greater than or equal to 0.15 μm, the thickness of the Ni-plated steel foil is 5 to 50 μm, the tensile strength is over 400 MPa but no greater than 1200 MPa, and the surface defect area percentage is less than or equal to 5.00% for both surfaces of the Ni-plated steel foil.