Copper foil having improved adhesive force, electrode including the same, secondary battery including the same, and method of manufacturing the same
Provided is a copper foil. The copper foil includes a copper layer and a protective layer disposed on the copper layer, wherein a surface of the protective layer has a maximum height roughness (R max ) of 0.6 μm to 3.5 μm, a peak density (PD) of 5 to 110, and an oxygen atomic amount of 22 at % (atomic %) to 67 at %.
1. A copper foil comprising:
a copper layer; and
a protective layer disposed on the copper layer,
wherein a surface of the protective layer has a maximum height roughness (R max ) of 0.6 μm to 3.5 μm, a peak density (PD) of 5 to 110, and an oxygen atomic amount of 22 at% (atomic%) to 67 at%.
2. The copper foil of claim 1 , wherein the protective layer includes at least one of chromium, a silane compound, and a nitrogen compound.
3. The copper foil of claim 1 , wherein the copper foil has a yield strength of 25 kgf/mm 2 or more at a room temperature of 25±15° C.
4. The copper foil of claim 1 , wherein the copper foil has an elongation of 2% or more at a room temperature of 25±15° C.
5. The copper foil of claim 1 , wherein the copper foil has a yield strength ratio of 0.55 kgf/mm 2 or more represented by the following Equation 1:
Yield strength ratio (kgf/mm 2 )=Yield strength(kgf/mm 2 )×Elongation value, wherein, the elongation value has no unit. [Equation 1]
6. The copper foil of claim 1 , wherein the copper foil has a thickness of 4 μm to 30 μm.
7. A secondary battery electrode comprising:
a copper foil; and
an active material layer disposed on the copper foil,
wherein the copper foil includes:
a copper layer; and
a protective layer disposed between the copper layer and the active material layer,
wherein a surface of the copper foil has a maximum height roughness (R max ) of 0.6 μm to 3.5 μm, a peak density (PD) of 5 to 110, and an oxygen atomic amount of 22 at% to 67 at%.
8. The secondary battery electrode of claim 7 , wherein the protective layer includes at least one of chromium, a silane compound, and a nitrogen compound.
9. The secondary battery electrode of claim 7 , wherein the copper foil has a yield strength of 25 kgf/mm 2 or more and an elongation of 2% or more at a room temperature of 25±15° C.
10. A secondary battery comprising:
a cathode;
an anode including the secondary battery electrode according to any one of claims 7 to 9 ;
an electrolyte configured to provide an environment in which lithium ions move between the cathode and the anode; and
a separator configured to electrically insulate the cathode from the anode.