Electrodeposited copper foil and electrode, and lithium-ion secondary battery comprising the same

Abstract

Provided are an electrodeposited copper foil, an electrode comprising the same, and a lithium-ion secondary battery comprising the same. The electrodeposited copper foil has a drum side and a deposited side opposing the drum side, wherein at least one of the drum side and the deposited side exhibits a void volume value (Vv) in the range of 0.17 μm.sup.3/μm.sup.2 to 1.17 μm.sup.3/μm.sup.2; and an absolute value of a difference between a maximum height (Sz) of the drum side and a Sz of the deposited side is in the range of less than 0.60 μm.

Claims

1. An electrodeposited copper foil comprising a drum side and a deposited side opposing the drum side, wherein at least one of the drum side and the deposited side exhibits a void volume (Vv) in the range of 0.17 μm.sup.3/μm.sup.2 to 1.17 μm.sup.3/μm.sup.2; and an absolute value of a difference between a maximum height (Sz) of the drum side and a Sz of the deposited side is in the range of less than 0.60 μm; wherein a void volume is obtained according to Standard Method ISO 25178-2:2012; the Vv refers to a void volume at a material ratio of 10%; the Sz is obtained according to Standard Method ISO 25178-2:2012.

2. The electrodeposited copper foil of claim 1, wherein the drum side exhibits a Vv in the range of 0.17 μm.sup.3/μm.sup.2 to 1.17 μm.sup.3/μm.sup.2 and the deposited side exhibits a Vv in the range of 0.17 μm.sup.3/μm.sup.2 to 1.17 μm.sup.3/μm.sup.2.

3. The electrodeposited copper foil of claim 1, wherein at least one of the drum side and the deposited side exhibits a core void volume (Vvc) in the range of 0.16 μm.sup.3/μm.sup.2 to 1.07 μm.sup.3/μm.sup.2; wherein the Vvc is a difference in void volume between a first material ratio of 10% and a second material ratio of 80%.

4. The electrodeposited copper foil of claim 1, wherein the drum side exhibits a Vvc in the range of 0.16 μm.sup.3/μm.sup.2 to 1.07 μm.sup.3/μm.sup.2 and the deposited side exhibits a Vvc in the range of 0.16 μm.sup.3/μm.sup.2 to 1.07 μm.sup.3/μm.sup.2; wherein the Vvc is a difference in void volume between a first material ratio of 10% and a second material ratio of 80%.

5. The electrodeposited copper foil of claim 1, wherein at least one of the drum side and the deposited side exhibits a dale void volume (Vvv) in the range of 0.01 μm.sup.3/μm.sup.2 to 0.10 μm.sup.3/μm.sup.2; wherein the Vvv refers to a void volume at a material ratio of 80%.

6. The electrodeposited copper foil of claim 1, wherein the drum side exhibits a Vvv in the range of 0.01 μm.sup.3/μm.sup.2 to 0.10 μm.sup.3/μm.sup.2 and the deposited side exhibits a Vvv in the range of 0.01 μm.sup.3/μm.sup.2 to 0.10 μm.sup.3/μm.sup.2; wherein the Vvv refers to a void volume at a material ratio of 80%.

7. The electrodeposited copper foil of claim 4, wherein the drum side exhibits a Vvv in the range of 0.01 μm.sup.3/μm.sup.2 to 0.10 μm.sup.3/μm.sup.2 and the deposited side exhibits a Vvv in the range of 0.01 μm.sup.3/μm.sup.2 to 0.10 μm.sup.3/μm.sup.2; wherein the Vvv refers to a void volume at a material ratio of 80%.

8. The electrodeposited copper foil of claim 1, wherein at least one of the drum side and the deposited side exhibits a Sz in the range of 1.24 μm to 3.25 μm.

9. The electrodeposited copper foil of claim 1, wherein the drum side exhibits a Sz in the range of 1.24 μm to 3.25 μm and the deposited side exhibits a Sz in the range of 1.24 μm to 3.25 μm.

10. The electrodeposited copper foil of claim 1, wherein the electrodeposited copper foil has a thickness in the range of 2 μm to 25 μm.

11. The electrodeposited copper foil of claim 1, wherein the electrodeposited copper foil exhibits a ratio of a fatigue life of the electrodeposited copper foil to a thickness of the electrodeposited copper foil in the range of more than 5 times/μm.

12. The electrodeposited copper foil of claim 11, wherein the ratio of a fatigue life of the electrodeposited copper foil to a thickness of the electrodeposited copper foil is in the range of 8 times/μm to 40 times/μm.

13. The electrodeposited copper foil of claim 1, wherein the electrodeposited copper foil comprises a bare copper foil and a surface-treated layer disposed on the bare copper foil; the drum side and the deposited side are respectively on both outermost surfaces of the electrodeposited copper foil, and an outermost surface of the surface-treated layer is the drum side or the deposited side.

14. The electrodeposited copper foil of claim 13, wherein the surface-treated layer is at least one selected from the group consisting of: a zinc-chromium layer, a chromium layer, and an organic layer.

15. An electrode for a lithium-ion secondary battery comprising the electrodeposited copper foil of claim 1, at least one binder and at least one active substance.

16. The electrode for a lithium-ion secondary battery of claim 15, wherein the binder and the active substance are in contact with the deposited side of the electrodeposited copper foil.

17. The electrode for a lithium-ion secondary battery of claim 15, wherein the binder and the active substance are in contact with the drum side of the electrodeposited copper foil.

18. A lithium-ion secondary battery comprising the electrode for a lithium-ion secondary battery of claim 15.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic plot of Vv in an areal material ratio plot.

(2) FIG. 2 shows a schematic plot of Vvc and Vvv in an areal material ratio plot.

DETAILED DESCRIPTION OF THE DISCLOSURE

(3) Hereinafter, one skilled in the art can easily realize the advantages and effects of the instant disclosure from the following examples. Therefore, it should be understood that the descriptions proposed herein are just preferable examples for the purpose of illustrations only, not intended to limit the scope of the disclosure. Various modifications and variations could be made in order to practice or apply the instant disclosure without departing from the spirit and scope of the instant disclosure.

(4) <Electrodeposited Copper Foil>

Examples 1 to 7 (E1 to E7), Comparative Examples 1 to 7 (C1 to C7): Electrodeposited Copper Foil

(5) The manufacturing apparatus for preparing electrodeposited copper foils comprises an electrodeposition equipment, a series of guide rollers and a surface treatment equipment. The electrodeposition equipment comprises a rotatable cathode drum and an insoluble anode, a copper electrolyte solution and a feed pipe. The insoluble anode is arranged at the lower half of the cathode drum and surrounds the cathode drum. The cathode drum and the anode plate are spaced apart from each other and allow the copper electrolyte solution to be introduced through the feed pipe. The surface treatment equipment comprises an anti-tarnish treatment tank and electrode plates disposed therein.

(6) During the manufacturing process of preparing Examples 1, 4 to 7 and Comparative Example 4, as indicated in Table 1 below, the insoluble anode was covered with an anode bag (product model: BEIP308W10L20, manufactured by Taiwan Grace International Corp). The anode bag enclosed the insoluble anode but was open at the top, above the fluid level of the copper electrolyte solution. This allowed oxygen bubbles to flow out of the copper electrolyte solution and be away from the surface of the insoluble anode.

(7) In the electrodeposition step, a continuous direct current was applied to make the copper electrolyte solution flow between the cathode drum and the insoluble anode to make copper ions in the copper electrolyte solution continuously electrodeposited on the surface of the cathode drum and thereby forming the bare copper foil. Subsequently, the bare copper foil was peeled off from the cathode drum and guided to one of the guide rollers. After that, the bare copper foil was transported to the surface treatment equipment to undergo an anti-tarnish treatment. The bare copper foil was immersed in an anti-tarnish treatment tank filled with an anti-tarnish solution, and a continuous electroplating was applied to both of the opposite surfaces of the bare copper foil by using the electrode plates, thereby forming two surface-treated layers (i.e. anti-tarnish layers) respectively attached on both of the surfaces of the bare copper foil.

(8) The composition of the copper electrolyte solution and the manufacturing parameters of the electrodeposition step were as follows.

(9) 1. The composition of the copper electrolyte solution:

(10) (1) Sulfuric acid with a concentration of 50 wt %: 75 grams per liter (g/L);

(11) (2) Copper sulfate (CuSO.sub.4.5H.sub.2O): 280 g/L;

(12) (3) Chloride ion (derived from HCl, purchased from RCI Labscan Ltd.): 15 milligrams per liter (mg/L);

(13) (4) Cerium citrate (Ce(SO.sub.4).sub.2): 0 milligram per liter (mg/L) to 55 mg/L (purchased from Sigma-Aldrich), wherein the content ratios of the cerium citrate in the copper electrolyte solution used to prepare the electrodeposited copper foils of E1 to E7 and C1 to C7 were listed in Table 1.

(14) 2. Manufacturing parameters:

(15) (1) Temperature of the copper electrolyte solution: 40° C.;

(16) (2) Current density: 33 amperes per square decimeter (A/dm.sup.2) to 65 A/dm.sup.2.

(17) Wherein the current densities applied to prepare the electrodeposited copper foils of E1 to E7 and C1 to C7 were listed in Table 1.

(18) The composition of the anti-tarnish solution and the manufacturing parameters of the anti-tarnish treatment were listed below.

(19) 1. The composition of the anti-tarnish solution: chromic acid (CrO.sub.3): 1500 mg/L (purchased from Sigma-Aldrich).

(20) 2. Manufacturing parameters:

(21) (1) Temperature of the anti-tarnish solution: 25° C.;

(22) (2) Current density: 0.5 A/dm.sup.2;

(23) (3) Plating time: 1 second (sec).

(24) Analysis 1: Weight and Average Thickness Per Unit Area of the Electrodeposited Copper Foil

(25) Each of the electrodeposited copper foils of Examples 1 to 7 and Comparative Examples 1 to 7 was cut into a test sample of 100 mm in length and width, and each test sample was weighed by the microbalance AG-204 (purchased from Mettler Toledo International Inc.); further, the measured weight value of each test sample was divided by its area, thereby obtaining the weight per unit area of each of the electrodeposited copper foils (unit: g/m.sup.2).

(26) Moreover, according to the Standard Method of IPC-TM-650 2.4.18, the density of the electrodeposited copper foils was about 8.909 g/cm.sup.3. Then, an average thickness of each of the electrodeposited copper foils of E1 to E7 and C1 to C7 was respectively calculated by the following formula (I). Therefore, the weight per unit area and average thickness of each of the electrodeposited copper foils of E1 to E7 and C1 to C7 were listed in Table 1.
Average thickness(μm)=weight per unit area(g/m.sup.2)/density of the electrodeposited copper foil(g/m.sup.3)  (I)

(27) TABLE-US-00001 TABLE 1 With or Content ratio Current Weight per Average Example Without of Ce(SO.sub.4).sub.2 density unit area thickness No. anode bag (mg/L) (A/dm.sup.2) (g/m.sup.2) (μm) E1 With 45 33 53.5 6.0 E2 Without 15 33 53.5 6.0 E3 Without 45 33 53.5 6.0 E4 With 55 65 53.5 6.0 E5 With 0 33 53.5 6.0 E6 With 45 33 25.4 2.9 E7 With 45 33 187.1 21.0 C1 Without 0 33 53.5 6.0 C2 Without 5 33 53.5 6.0 C3 Without 55 33 53.5 6.0 C4 With 55 33 53.5 6.0 C5 Without 55 65 53.5 6.0 C6 Without 45 38 53.5 6.0 C7 Without 50 43 53.5 6.0

(28) Analysis 2: Surface Texture Analysis of the Electrodeposited Copper Foil

(29) Surface texture of each of the electrodeposited copper foils of E1 to E7 and C1 to C7 was observed by a laser scanning confocal microscope and the resulting images were taken. Moreover, the respective Vv, Vvc and Vvv of the drum side and the deposited side of the electrodeposited copper foils of E1 to E7 and C1 to C7 were analyzed in accordance with the Standard Method of ISO 25178-2: 2012, and then the analytical results were listed in Table 2. In addition, the relevant instruments and test conditions were recorded as follows.

(30) 1. Instruments:

(31) (1) Laser scanning confocal microscope: Model: LEXT OLS5000-SAF manufactured by Olympus;

(32) (2) Objective lenses: MPLAPON-100xLEXT.

(33) 2. Test conditions:

(34) (1) Analytical environment: temperature of 24±3° C. and a relative humidity of 63±3%;

(35) (2) Light source: 405 nm-wavelength;

(36) (3) Objective lens magnification: 100× magnification;

(37) (4) Optical zoom: 1.0×;

(38) (5) Image area: 129 μm×129 μm;

(39) (6) Resolution: 1024 pixels×1024 pixels;

(40) (7) Condition setting: auto tilt removal;

(41) (8) Filter setting: no filter.

(42) Vv was calculated at a material ratio of 10%.

(43) Further, Vvv was calculated at a material ratio of 80%.

(44) Further, Vvc was a difference in void volume between the material ratios of 10% and 80%.

(45) Analysis 3: Sz Analysis of the Electrodeposited Copper Foil

(46) According to the Standard Method of ISO 25178-2: 2012, the respective Sz of the drum side and the deposited side of the electrodeposited copper foils of E1 to E7 and C1 to C7 were measured, and then an absolute value of the resulting difference between the Sz of the drum side and the Sz of the deposited side in each group was respectively calculated, and the analytical results were listed in Table 2. Besides, the relevant test conditions were recorded as the same as Analysis 2.

(47) TABLE-US-00002 TABLE 2 Vv (μm.sup.3/μm.sup.2) Vvc (μm.sup.3/μm.sup.2) Vvv (μm.sup.3/μm.sup.2) Sz (μm) Example Drum Deposited Drum Deposited Drum Deposited Drum Deposited ΔSz No. Side side side side Side side side side (μm) E1 0.17 0.20 0.16 0.18 0.01 0.02 2.57 2.18 0.39 E2 1.17 1.14 1.07 1.05 0.10 0.09 1.47 1.99 0.52 E3 0.72 0.75 0.65 0.68 0.07 0.07 2.07 2.64 0.57 E4 0.33 1.02 0.29 0.92 0.04 0.10 3.25 2.99 0.26 E5 0.28 0.25 0.23 0.22 0.05 0.03 1.24 1.42 0.18 E6 0.18 0.21 0.17 0.17 0.01 0.04 2.69 2.34 0.35 E7 0.19 0.19 0.17 0.16 0.02 0.03 2.42 2.49 0.07 C1 1.44 1.47 1.29 1.31 0.15 0.16 0.66 1.37 0.71 C2 1.50 1.52 1.29 1.29 0.21 0.23 0.71 1.40 0.69 C3 0.06 0.05 0.05 0.04 0.01 0.01 3.63 3.03 0.60 C4 0.04 0.03 0.03 0.02 0.01 0.01 2.99 2.74 0.25 C5 0.43 1.33 0.38 1.21 0.05 0.12 3.76 4.41 0.65 C6 0.23 0.44 0.16 0.38 0.07 0.06 2.14 2.75 0.61 C7 0.26 0.53 0.18 0.44 0.08 0.09 2.18 2.93 0.75

(48) Analysis 4: Fatigue Life Analysis of the Electrodeposited Copper Foil

(49) According to Standard Method IPC-TM-650 2.4.2.1, respective fatigue lives of the electrodeposited copper foils of E1 to E7 and C1 to C7 were each measured by a fatigue ductility tester.

(50) Each of the electrodeposited copper foils of Examples and Comparative Examples was cut into a thin strip-shaped test sample with 200 mm at the machine direction (“MD”). Subsequently, the thin strip-shaped test sample was attached to a sample holder hung with a weight by using an adhesive tape so that the thin strip-shaped test sample did not slip from the sample holder. Then, the center of the test sample was rapidly vibrated up and down by using a mandrel with a set diameter. The fatigue ductility tester was used to count how many times of vibration while the surface of the test sample had a fracture, and the analysis results were listed in Table 3; furthermore, the ratio of the fatigue life of each electrodeposited foil to the thickness of the electrodeposited copper foil was calculated, and the ratios were also listed in Table 3. In addition, the relevant test conditions were as follows.

(51) 1. Fatigue ductility tester: Model 3FDF (purchased from Jovil Universal Manufacturing Company);

(52) 2. Size of test sample: 200 mm in length and 12.7 mm in width;

(53) 3. Diameter of mandrel: 0.8 mm;

(54) 4. Vibration frequency: 100 vibrations per minute;

(55) 5. Loading of tension: 84.6 g.

(56) TABLE-US-00003 TABLE 3 Average Ratio of Fatigue Thickness Fatigue Life Life to Thickness Example No. (μm) (times) (times/μm) E1 6.0 243 40 E2 6.0 51 8 E3 6.0 157 26 E4 6.0 163 27 E5 6.0 188 31 E6 2.9 109 38 E7 21.0 789 38 C1 6.0 29 5 C2 6.0 15 2 C3 6.0 12 2 C4 6.0 145 24 C5 6.0 10 2 C6 6.0 19 3 C7 6.0 21 4
<Electrodes for a Lithium-Ion Secondary Battery>

Examples 1-A to 7-A and Comparative Examples 1-A to 7-A: Electrodes

(57) A negative electrode slurry was coated on the two opposite outermost surfaces (i.e. the drum side and the deposited side) of each of the electrodeposited copper foils of E1 to E7 and C1 to C7 respectively. After a completion of drying, the coated electrodeposited copper foils were then pressed by a pressing machine to obtain negative electrodes for a lithium-ion secondary battery, which were electrodes of Examples 1-A to 7-A and Comparative Examples 1-A to 7-A. Wherein, the negative electrode slurry was composed of 100 parts by weight of a negative electrode active material and 60 parts by weight of 1-Methyl-2-pyrrolidone (“NMP”). The composition of the negative electrode active material and the concerned manufacturing parameters were listed below.

(58) 1. The composition of the negative electrode active material:

(59) (1) Mesophase graphite powder (“MGP”): 93.9 wt %;

(60) (2) Conductive additive: 1 wt % of conductive carbon black (Super P®);

(61) (3) Solvent-based binder: 5 wt % of poly-1,1-difluoroethene (PVDF 6020);

(62) (4) Oxalic acid: 0.1 wt %.

(63) 2. The manufacturing parameters:

(64) (1) Coating speed: 5 meters per minute (m/min);

(65) (2) Coating thickness: 200 μm;

(66) (3) Drying temperature: 160° C.;

(67) (4) Material, size and hardness of a roller of the pressing machine: high-carbon chrome bearing steel (SUJ2); 250 mm×250 mm; 62 to 65 HRC;

(68) (5) Speed and pressure: 1 m/min; 3000 pound per square inch (psi).

(69) Analysis 5: Wet Adhesion Test

(70) Each electrode was cut into a test sample with a set size and immersed in a specific electrolyte solution during a particular period. If the negative electrode material was delaminated from the electrodeposited copper foil or swollen on the electrodeposited copper foil, it was considered that the adhesive strength between the electrodeposited copper foil and negative electrode material was poor, which was evaluated as “fail.” On the contrary, if there was no delamination or swelling, it was evaluated as “pass.” In addition, the relevant test conditions were as follows.

(71) 1. Test sample size: 100 mm×100 mm;

(72) 2. Electrolyte solution: Model: LBC322-01H, manufactured by Shenzhen Capchem Technology Co, Ltd.;

(73) 3. Immersing temperature and time: 60° C. and 4 hours.

(74) The analytical results of the electrodes for a lithium-ion secondary battery of Examples 1-A to 7-A (respectively comprising the electrodeposited copper foils of E1 to E7) and Comparative Examples 1-A to 7-A (respectively comprising the electrodeposited copper foils of C1 to C7) were listed in Table 4.

(75) Analysis 6: Wrinkle Test of the Electrodeposited Copper Foil which was Comprised in the Electrode

(76) Since the electrodes for a lithium-ion secondary battery of Examples 1-A to 7-A and Comparative Examples 6-A and 7-A passed the wet adhesion test, it showed that the concerned electrodeposited copper foils and the negative electrode active material of the electrodes had a certain adhesive strength, which can ensure that the negative electrode active material would not peel off during the coating process, so the respective electrodeposited copper foils contained in the electrodes were further subjected to a wrinkle test. Accordingly, other test samples of the electrodeposited copper foils of E1 to E7, C6 and C7 were taken. Then, the negative electrode slurry was coated on both surfaces of the test samples and dried directly. After that, the aforementioned sample respectively placed between two horizontal fixed rollers with a distance of 700 mm. Then, the surface of the test samples respectively was visually observed for wrinkles when the test samples were applied a tension of 10 kg. If there was no wrinkle on the surface, it was evaluated as “pass”; however, if there was any wrinkle on the surface, it was evaluated as “fail.” The analytical results were listed in Table 4. In addition, the relevant test conditions were as follows.

(77) 1. Coating thickness of the negative electrode slurry: 200 μm;

(78) 2. Drying temperature: 160° C.

(79) <Lithium-Ion Secondary Battery>

Examples 1-B to 7-B and Comparative Examples 1-B to 7-B: Lithium-Ion Secondary Batteries

(80) The negative electrodes of the foregoing Examples 1-A to 7-A and Comparative Examples 1-A to 7-A can be further matched with the positive electrodes to form lithium-ion secondary batteries of Examples 1-B to 7-B and Comparative Examples 1-B to 7-B.

(81) Specifically, the positive electrode of the lithium-ion secondary battery could be prepared roughly through the following steps.

(82) A positive electrode slurry was coated on an aluminum foil. After the contained solvent evaporated, the coated aluminum foil was pressed by a pressing machine to obtain the positive electrode. Wherein, the positive electrode slurry was composed of 100 parts by weight of a positive electrode active material and 195 parts by weight of NMP. The composition of the positive electrode active material was listed below.

(83) 1. Positive electrode active substance: lithium cobalt(III) oxide (LiCoO.sub.2): 89 wt %;

(84) 2. Conductive additives:

(85) (1) Flaked graphite (KS6): 5 wt %;

(86) (2) Conductive carbon black (Super P®): 1 wt %;

(87) 3. Solvent-based binder: poly-1,1-difluoroethene (PVDF 1300): 5 wt %.

(88) Subsequently, the positive and negative electrodes were cut to a specific size, and then the positive and negative electrodes are alternately stacked with microporous separators (Model: Celgard 2400, manufactured by Celgard Company) sandwiched therebetween, and placed in a press mold filled with an electrolyte solution (Model: LBC322-01H, purchased from Shenzhen Capchem Technology Co, Ltd.), and then sealed to form a laminated type lithium-ion secondary battery. The size of the laminated type lithium-ion secondary battery was 41 mm×34 mm×53 mm.

(89) Analysis 7: Cycle Life Test

(90) The lithium-ion secondary batteries of the Examples 1-B to 7-B and Comparative Examples 1-B to 7-B, as the test samples, were subjected to charge-discharge cycle tests. The specific test conditions of the charge-discharge cycle test were as follows.

(91) 1. Charging mode: constant current-constant voltage (“CCCV”);

(92) (1) Charging voltage: 4.2 Volts (“V”);

(93) (2) Charging current: 5 C;

(94) 2. Discharging mode: constant current mode (“CC”);

(95) (1) Discharging voltage: 2.8 V;

(96) (2) Discharging current: 5 C;

(97) (3) Test temperature: about 55° C.

(98) The cycle life was defined as the times of the charge-discharge cycles the lithium-ion secondary battery under the test can undergo when its capacity fell to 80% of its initial capacity. The cycle life analytical results of the lithium-ion secondary batteries of Examples 1-B to 7-B (respectively comprising the electrodeposited copper foils of E1 to E7) and Comparative Examples 1-B to 7-B (respectively comprising the electrodeposited copper foils of C1 to C7) were also listed in Table 4.

(99) TABLE-US-00004 TABLE 4 Electrodeposited Lithium-Ion Cycle Life Copper Foil No. Electrode No. Wet Adhesion Test Wrinkle Test Secondary Battery No. (times) Example 1 Example 1-A Pass Pass Example 1-B 1330 Example 2 Example 2-A Pass Pass Example 2-B 819 Example 3 Example 3-A Pass Pass Example 3-B 1247 Example 4 Example 4-A Pass Pass Example 4-B 953 Example 5 Example 5-A Pass Pass Example 5-B 1352 Example 6 Example 6-A Pass Pass Example 6-B 1342 Example 7 Example 7-A Pass Pass Example 7-B 1325 Comparative Comparative Fail — Comparative Example 695 Example 1 Example 1-A 1-B Comparative Comparative Fail — Comparative Example 702 Example 2 Example 2-A 2-B Comparative Comparative Fail — Comparative Example 647 Example 3 Example 3-A 3-B Comparative Comparative Fail — Comparative Example 685 Example 4 Example 4-A 4-B Comparative Comparative Fail — Comparative Example 694 Example 5 Example 5-A 5-B Comparative Comparative Pass Fail Comparative Example 764 Example 6 Example 6-A 6-B Comparative Comparative Pass Fail Comparative Example 739 Example 7 Example 7-A 7-B

(100) (Discussion of Experimental Results)

(101) From the results of Tables 2 to 4, since the electrodeposited copper foils of E1 to E7 have at least one of the drum side and the deposited side with a Vv in an appropriate range (i.e. Vv is in the range of 0.17 μm.sup.3/μm.sup.2 to 1.17 μm.sup.3/μm.sup.2) and control a ΔSz in an appropriate range (i.e. ΔSz is smaller than 0.60 μm), the electrodeposited copper foils of E1 to E7 not only have good mechanical properties of achieving 50 and above times in the fatigue life test; more importantly, in the electrodes of Examples 1-A to 7-A, the drum side and the deposited side of the electrodeposited copper foil can have sufficient adhesion strength to the negative electrode active material, thereby passing the wet adhesion test, in addition to passing the wrinkle test. Moreover, the charge-discharge cycle life of the lithium-ion secondary batteries of Examples 1-B to 7-B can reach 800 and above times. It demonstrated that the electrodeposited copper foil of the instant disclosure indeed has improved mechanical properties and excellent anti-wrinkle properties, thereby reducing or even avoiding the occurrence of wrinkles and fractures of the electrodeposited copper foil.

(102) Referring to the electrodeposited copper foils of C1 to C7, since the drum side and the deposited side, for which the above-mentioned two characteristics were not controlled at the same time, the analytical results of the fatigue life for the electrodeposited copper foils of C1 to C7 were all worse. Besides, from the result that the electrodes of Comparative Examples 1-A to 5-A failed the wet adhesion test, it can be seen that the Vv of the at least one of the drum side and the deposited side of the electrodeposited copper foils was not controlled within the appropriate range, so the at least one of the drum side and the deposited side of the electrodeposited copper foils did not have enough adhesion strength to the negative electrode active material in the electrodes of Comparative Examples 1-A to 5-A. In addition, even though the electrodes of Comparative Examples 6-A and 7-A passed the wet adhesion test, there was still an occurrence of wrinkles. Accordingly, all the cycle lives of the lithium-ion secondary batteries of Comparative Examples 1-B to 7-B were less than 800 times, whose cycle life performances were significantly inferior to those of the lithium-ion secondary batteries of Examples 1-B to 7-B.

(103) Further analyzing the characteristics of the electrodeposited copper foils of C1 to C7, it shows that since the Vv of the at least one of the drum side and the deposited side of the electrodeposited copper foils of C6 and C7 respectively was controlled in the appropriate range but ΔSzs of the electrodeposited copper foils of C6 and C7 were not controlled within the appropriate range, the electrodeposited copper foils of C6 and C7 failed to pass the wrinkle test, and the cycle lives of the lithium-ion secondary batteries of Comparative Examples 6-B and 7-B containing the electrodeposited copper foils of C6 and C7 still did not achieve 800 times. The lithium-ion secondary batteries of Comparative Examples 6-B and 7-B still respectively had a poor cycle life. Based on the above results, it can be seen that if the Vv of one of the outermost surfaces of the electrodeposited copper foil (that is, the drum side or the deposited side) and the ΔSz of the both outermost surfaces are not simultaneously controlled within an appropriate range, when the electrodeposited copper foil is applied to a lithium-ion secondary battery, its cycle life cannot be extended.

(104) In addition, from the experimental results of Examples 1, 6 and 7, it can be seen that in the instant disclosure, either the electrodeposited copper foil of Example 6 with a thinner thickness (2.9 μm), the electrodeposited copper foil of Example 1 with a general thickness (6.0 μm) or the electrodeposited copper foil of Example 7 with a thicker thickness (21.0 μm), all three kinds of the electrodeposited copper foils can obtain the same good bending resistance. It demonstrated that the technical means of the instant disclosure indeed improve the processability and durability of electrodeposited copper foil. When the electrodeposited copper foils are prepared under the same conditions, the ratios of the fatigue life to the thickness are almost the same, which means that all electrodeposited copper foils with different thicknesses can extend their fatigue life through the technical means of the instant disclosure. Especially for the thinner electrodeposited copper foil, the traditional thinner electrodeposited copper foil mostly has the problem of poor fatigue life. However, the ratio of the fatigue life of the electrodeposited copper foil to the thickness of the electrodeposited copper foil of Example 6 was roughly the same as the ratio of the fatigue life to the thickness of the electrodeposited copper foil of Examples 1 and 7. Therefore, it can be seen that the instant disclosure has a stronger effect of extending the fatigue life of the thin electrodeposited copper foil.

(105) In summary, the instant disclosure simultaneously adjusts the surface texture characteristics (i.e. Vv) of the drum side and/or the deposited side of the electrodeposited copper foil and controls the profile characteristics of the drum side and the deposited side (i.e. ΔSz), the mechanical strength of the electrodeposited copper foil can be specifically enhanced and the adhesion strength between the electrodeposited copper foil and the active material can also be enhanced, thereby realizing an improvement in prolonging the charge-discharge cycle life of the lithium-ion secondary battery and improving the performance of the battery.

(106) The above-mentioned embodiments are merely examples for the convenience of description, but these embodiments are not used to limit the scope of the claims of the instant disclosure. All other changes or modifications completed without departing from the content of this disclosure should all be included in the scope of claims covered by this disclosure.