Patent ID: 8182945

Claim:
A current collector comprising a substrate comprising a metal sheet, wherein said substrate has a first portion and a plurality of second portions on at least one face of said substrate, said second portions are distributed on said substrate, said first portion is the portion of said substrate excluding said second portions, said first portion has a plurality of projections, an average height of said projections is 3 to 10 μm, each of said projections has a cross-sectional diameter of 1 to 50 μm in a direction parallel to said substrate, a number of said projections is 10,000 to 10,000,000 per cm 2 of the face of said substrate on which said first and second portions are formed, each of said second portions has 2 to 100 adjacent minute projections, said minute projections have a height that is below 35% of the average height of said projections, and a number of said second portions is 5 to 1000 per cm 2 of the face of said substrate on which said first and second portions are formed wherein the tip said plurality of projections is substantially flat.