Electrode for secondary battery having fine holes
Disclosed herein is an electrode for a secondary battery including an electrode mixture layer including an electrode active material on one surface or both surfaces of a current collector, wherein the electrode mixture layer includes a plurality of fine holes recessed toward the current collector from a vertical cross-sectional surface, and each of the fine holes is a horn-shaped hole whose diameter is gradually decreased from the vertical cross-sectional surface toward the current collector in the electrode mixture layer.
1. An electrode for a secondary battery comprising: an electrode mixture layer including an electrode active material on one surface or both surfaces of a current collector, wherein the electrode mixture layer includes a plurality of fine holes recessed toward the current collector from a vertical cross-sectional surface thereof, and each of the fine holes is a horn-shaped hole whose diameter is linearly decreased from the vertical cross-sectional surface to an inner end part having a circular arc shape.
2. The electrode of claim 1 , wherein the fine holes are formed in an electrode mixture layer having a loading amount of about 3.5 to 5.5 mAh/cm2 and a porosity of about 25 to 35%.
3. The electrode of claim 1 , wherein a depth of each of the fine holes formed from the vertical cross-sectional surface toward the current collector is about 80 to 90% of a thickness of the electrode mixture layer corresponding thereto.
4. The electrode of claim 1 , wherein the fine holes have the shape of a triangle, a quadrangle, a pentagon, a hexagon, a circle, a semicircle, or an ellipse on a plane on a surface part of the electrode mixture layer.
5. The electrode of claim 1 , wherein the fine holes have an average diameter of about 100 to 200 micrometers at the vertical cross-sectional surface, and have an average diameter of about 20 to 50 micrometers at an inner end part thereof.
6. The electrode of claim 1 , wherein the fine holes have a regular array structure on a plane on a surface part of the electrode mixture layer.
7. The electrode of claim 1 , wherein the fine holes have a structure in which a diameter is continuously or discontinuously decreased from the vertical cross-sectional surface toward the current collector.
8. A device for manufacturing the electrode for a secondary battery according to claim 1 , comprising: a fine hole forming mold, wherein the fine hole forming mold has a structure in which horn-shaped protrusions corresponding to fine holes protrude from one surface thereof so that, when the one surface is pressed against a surface of an electrode mixture layer, horn-shaped fine holes recessed from a surface part of the electrode mixture layer toward a current collector are formed.
9. A device for manufacturing the electrode for a secondary battery according to claim 1 , comprising: a fine hole forming roller, wherein the fine hole forming roller has a structure in which horn-shaped protrusions corresponding to fine holes protrude from an outer surface thereof so that, when the outer surface is pressed against a surface of an electrode mixture layer, horn-shaped fine holes recessed from a surface part of the electrode mixture layer toward a current collector are formed.
10. The device of claim 8 , wherein the horn-shaped protrusions have an average diameter of about 100 to 200 micrometers at an end part having a relatively large diameter, and an average diameter of about 20 to 50 micrometers at an end part having a relatively small diameter in a vertical cross-sectional surface thereof.
11. The device of claim 9 , wherein the horn-shaped protrusions have an average diameter of about 100 to 200 micrometers at an end part having a relatively large diameter, and an average diameter of about 20 to 50 micrometers at an end part having a relatively small diameter in a vertical cross-sectional surface thereof.
12. A method of manufacturing the electrode for a secondary battery according to claim 1 , comprising: coating an electrode mixture slurry including an electrode active material on a current collector; drying and rolling the current collector coated with the electrode mixture slurry to form an electrode mixture layer; and forming a plurality of horn-shaped fine holes recessed into the electrode mixture layer by pressing a mold or a roller against a surface of the electrode mixture layer.
13. The method of claim 12 , wherein the electrode mixture layer formed in the above process has a loading amount of about 3.5 to 5.5 mAh/cm2 and a porosity of about 25 to 35%.
14. The method of claim 12 , wherein the mold or the roller includes fine hole forming protrusions in a shape corresponding to the horn-shaped fine holes at a part facing the surface of the dried and rolled electrode mixture layer.
15. The method of claim 14 , wherein each of the horn-shaped protrusions has an average diameter of about 100 to 200 micrometers at an end part thereof having a relatively large diameter, and an average diameter of about 20 to 50 micrometers at an end part having a relatively small diameter in a vertical cross-sectional surface thereof.