Electrodeposited copper foil and method for producing the same, and current collector for lithium secondary battery and secondary battery comprising the electrodeposited copper foil
An electrodeposited copper foil of high toughness having a lightness L* value of the deposit side in the range of 36 to 74, the copper foil having a tensile strength in the range of 40 to 70 kg/mm 2 , and a weight deviation of less than 3%. The electrodeposited copper foils are particularly useful as current collectors for anode components of rechargeable secondary batteries and tend not to form wrinkles during charge-discharge cycles of the battery and are resistant to fracture during pressing of the anode active materials onto the copper foil. Secondary batteries and methods of manufacture are also described.
1. An electrodeposited copper foil having a drum side and an opposite non-roughened deposit side;
the electrodeposited copper foil having a tensile strength in the range of 40 to 70 kg/mm 2 ;
wherein a surface roughness (Rz) of the opposite non-roughened deposit side of the electrodeposited copper foil is greater than 0.5 μm and lower than 2.0 μm;
a lightness L* value of the deposit side, based on the L*a*b* color system described in JIS Z 8729, in the range of 40.43 to 74; and,
a weight deviation (in %) calculated according to the following relationship for a 50 mm in length×50 mm in width sample:
Weight
deviation
(
%
)
=
Maximum
area
weight
(
g
/
m
2
)
-
minimum
area
weight
(
g
/
m
2
)
Average
area
weight
×
100
of less than 3.
2. The electrodeposited copper foil of claim 1 , wherein the surface roughness (Rz) of the drum side of the electrodeposited copper foil is lower than 2.5 μm.
3. The electrodeposited copper foil of claim 2 , wherein a difference in surface roughness (Rz) between the drum side and the opposite non-roughened deposit side is at most 1.3 μm.
4. The electrodeposited copper foil of claim 1 , wherein the tensile strength is in the range of 40 to 60 kg/mm 2 .
5. The electrodeposited copper foil of claim 1 , wherein the weight deviation is less than 2.
6. The electrodeposited copper foil of claim 1 , wherein an a* value of the opposite non-roughened deposit side, based on the L*a*b* color system, is in the range of 11 to 18.
7. The electrodeposited copper foil of claim 1 , wherein a b* value of the opposite non-roughened deposit side, based on the L*a*b* color system, is in the range of 9 to 13.
8. The electrodeposited copper foil of claim 1 , wherein the electrodeposited copper foil comprises an elongation in the range of 4.7 to 6%.
9. The electrodeposited copper foil of claim 2 , wherein a difference in surface roughness (Rz) between the drum side and the opposite non-roughened deposit side is in the range of 0.10 to 0.70 μm.
10. A rechargeable lithium secondary battery comprising the electrodeposited copper foil of claim 1 .
11. An anode having a layer of anode active material in contact with the electrodeposited copper foil, wherein the electrodeposited copper foil is the electrodeposited copper foil of claim 1 .
12. A laminated type lithium secondary battery comprising the electrodeposited copper foil of claim 1 .
13. An electric vehicle (EV) comprising the rechargeable lithium secondary battery of claim 10 .
14. A method of making the electrodeposited copper foil of claim 1 , the method comprising:
providing a drum, the drum capable of rotating while at least partially submerged in a copper-containing electrolytic solution;
causing the copper-containing electrolytic solution to come in contact with the drum; applying a current through the copper-containing electrolytic solution between the drum,
which acts as a cathode, and an insoluble anode in contact with the copper-containing electrolytic solution;
electrodepositing copper from the copper-containing electrolytic solution on the drum to form the electrodeposited copper foil;
separating the electrodeposited copper foil from the drum; and,
recovering the electrodeposited copper foil.
15. The method of claim 14 , further comprising applying an anti-tarnish agent on the electrodeposited copper foil.
16. The method of claim 14 , wherein the copper-containing electrolytic solution comprises copper sulfate and sulfuric acid and at least
one additive selected from the group consisting of gelatin, sulfonic acid modified polyvinyl alcohol, N, N′-diethylthiourea, sodium 3-mercapto-1-propane sulfonate, chloride ion and combinations thereof.
17. The method of claim 15 , wherein the anti-tarnish agent comprises chromium.
18. The method of claim 15 , wherein the anti-tarnish agent comprises BTA (1,2,3-benzotriazole).
19. The electrodepodsited copper foil of claim 1 , wherein the tensile strength is in the range of 51.1 to 70 kg/mm 2 .