Electrode for secondary battery and manufacturing method thereof

1 . An electrode comprising:

a substrate;

a first coated portion disposed on a first surface of the substrate, the first coated portion comprising an active material; and

a first uncoated portion disposed on the first surface of the substrate, the first uncoated portion being in contact with the first coated portion and exposing the substrate,

wherein a first side portion of the first coated portion in contact with the first uncoated portion has a stepped surface;

the first side portion comprises first and second side walls joined together by the stepped surface; and

the first and second side walls are substantially perpendicular to the first surface of the substrate,

wherein the first coated portion comprises a first zone that is a central region spaced apart from the first side portion, and a second zone that includes the first side portion and is positioned between the first zone and the first uncoated portion, and

wherein a hardness of at least a portion of the second zone is greater than a hardness of the first zone.

2 . The electrode as claimed in claim 1 , wherein the substrate comprises a plurality of first uncoated portions each of which corresponds to the first uncoated portion disposed on the first surface of the substrate.

3 . The electrode as claimed in claim 1 , further comprising:

a second coated portion disposed on a second surface of the substrate; and

a second uncoated portion disposed on the second surface of the substrate, the second uncoated portion exposing the substrate,

wherein a second side portion of the second coated portion in contact with the second uncoated portion has a stepped surface.

4 . The electrode as claimed in claim 3 , wherein the second uncoated portion is formed at a position corresponding to the first uncoated portion.

5 . The electrode as claimed in claim 4 , wherein the substrate includes a plurality of first uncoated portions, each of which corresponds to the first uncoated portion disposed on the first surface of the substrate, and a plurality of second uncoated portions, each of which corresponds to the second uncoated portion disposed on the second surface of the substrate.

6 . An electrode assembly comprising:

a first electrode;

a second electrode; and

a separator disposed between the first electrode and the second electrode,

wherein the first electrode comprises:

a substrate having a first uncoated portion and a second uncoated portion respectively disposed on a first surface and a second surface thereof,

a first coated portion disposed on the first surface of the substrate, the first coated portion comprising a first active material, and

a second coated portion disposed on the second surface of the substrate, the second coated portion comprising a second active material,

wherein a first side portion of the first coated portion in contact with the first uncoated portion has a stepped surface;

the first side portion comprises first and second side walls joined together by the stepped surface; and

the first and second side walls are substantially perpendicular to the first surface of the substrate,

wherein the first coated portion comprises a first zone that is a central region spaced apart from the first side portion, and a second zone that includes the first side portion and is positioned between the first zone and the first uncoated portion, and

wherein a hardness of at least a portion of the second zone is greater than a hardness of the first zone.

7 . The electrode assembly as claimed in claim 6 , wherein a second side portion of the second coated portion in contact with the second uncoated portion has a stepped surface.