Electrolytic copper foil and preparation method therefor, and lithium battery

Abstract

The present application provides an electrolytic copper foil and a preparation method therefor, and a lithium battery. The electrolytic copper foil comprises copper having a content of greater than or equal to 99.9 wt% and a chlorine element having a content of 100-200 μg / g, and further comprises a gold element having a content of 80-200 μg / g and a platinum element having a content of 80-200 μg / g. The electrolytic copper foil containing the gold element and the platinum element can mitigate breakage occurring in the calendering process of lithium-ion batteries and reduce potential safety hazards during the use of batteries, thereby improving the elongation rate and the production process efficiency; in addition, minor addition of gold and platinum exhibits good electrical conductivity, thereby improving the electrical conductivity of the foil.

Description

Electrolytic copper foil, preparation method thereof, and lithium battery

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 29, 2024, with application number 202410122292X. The entire contents of the above application are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to an electrolytic copper foil and a preparation method thereof, as well as a lithium battery. Background Art

[0003] Copper foil, used as the negative electrode current collector in lithium-ion batteries, is a key material in lithium-ion battery manufacturing due to its excellent ductility, high gloss, and superior performance. During the lithium-ion battery manufacturing process, rolling the electrode sheet improves the peel strength between the active material and the current collector foil, increasing the cell's energy density. It also reduces the porosity between the active material, conductive agent, and binder within the electrode sheet, lowering the battery's resistance and ensuring consistent battery performance and the density and thickness of the electrode sheet surface material. Technical issues

[0004] During the cold pressing process of copper foil, as the energy density increases, the foil becomes thinner and thinner, and the foil may break during the rolling process, affecting production capacity; at the same time, the charging and discharging of the finished battery during use will also cause the copper foil to break, posing a safety hazard. Technical Solutions

[0005] In a first aspect, the present application provides an electrolytic copper foil comprising: a copper content ≥ 99.9 wt %, a chlorine content of 100-200 μg / g, and further comprising: a gold content of 80-200 μg / g, and a platinum content of 80-200 μg / g.

[0006] In a second aspect, the present application also provides a method for preparing an electrolytic copper foil, wherein additives are added to a sulfuric acid-copper sulfate solution, electrolysis is performed as an electrolyte, and the obtained raw foil is washed and dried to obtain an electrolytic copper foil; the additives include graphene oxide, guar gum, hydroxypropyl methylcellulose, polyethylene glycol, polyethyleneimine and chlorine-containing compounds, and the additives also include soluble salts of gold and soluble salts of platinum.

[0007] In a third aspect, the present application also provides a lithium battery, comprising the electrolytic copper foil provided in the present application or the electrolytic copper foil prepared by the preparation method provided in the present application. Beneficial effects

[0008] The beneficial effects of the electrolytic copper foil, its preparation method, and lithium battery provided in the present application are: the electrolytic copper foil prepared in the present application can improve the breakage of the lithium-ion battery during the rolling process and the safety hazards during the use of the battery. The addition of gold and platinum during the copper foil production process can improve the elongation, improve the process production efficiency and prevent the occurrence of safety accidents; at the same time, the addition of a small amount of gold and platinum has better conductivity, thereby improving the conductivity of the foil. Modes for Carrying Out the Invention

[0009] Example 1

[0010] Add the additive to the sulfuric acid-copper sulfate solution as the electrolyte and conduct the electrolysis at 45℃ and 53A / dm 2 Electrolysis is performed at a current density of , and the obtained raw foil is washed and dried to obtain electrolytic copper foil, specifically, water washing, acid washing, re-washing, polishing, and baking to obtain high-ductility electrolytic copper foil;

[0011] In the electrolyte:

[0012] Polyethylene glycol with a molecular weight of 4000 and a concentration of 8 mg / L;

[0013] Polyethyleneimine with a molecular weight of 9000 and a concentration of 35 mg / L;

[0014] The concentration of hydroxypropyl methylcellulose was 15 mg / L;

[0015] Cu 2+ The concentration of nitric acid is 65g / L, and the concentration of sulfuric acid is 120g / L;

[0016] Chlorine compounds Cl - The concentration is 20 mg / L;

[0017] Graphene oxide concentration 5 mg / L;

[0018] Guar gum concentration 12 mg / L;

[0019] The gold concentration of potassium gold cyanide is 20 mg / L;

[0020] The platinum concentration of platinum nitrate is 35 mg / L. Example

[0021] Add additives to sulfuric acid-copper sulfate solution as electrolyte, at 55℃ and 45A / dm 2 Electrolysis is performed at a current density of , and the obtained raw foil is washed and dried to obtain electrolytic copper foil, specifically, water washing, acid washing, re-washing, polishing, and baking to obtain high-ductility electrolytic copper foil;

[0022] In the electrolyte:

[0023] Polyethylene glycol with a molecular weight of 6000 and a concentration of 10 mg / L;

[0024] The molecular weight is 8000 polyethyleneimine, the concentration is 28 mg / L;

[0025] The concentration of hydroxypropyl methylcellulose was 10 mg / L;

[0026] Cu 2+ The concentration of nitric acid is 80g / L, and the concentration of sulfuric acid is 180g / L;

[0027] Chlorine compounds Cl - The concentration is 15 mg / L;

[0028] Graphene oxide concentration 5 mg / L;

[0029] Guar gum concentration 12 mg / L;

[0030] The gold concentration of potassium gold cyanide is 25 mg / L;

[0031] The platinum concentration of platinum nitrate is 25 mg / L. Example

[0032] Add the additive to the sulfuric acid-copper sulfate solution as the electrolyte and conduct the electrolysis at 60℃ and 70A / dm 2 Electrolysis is performed at a current density of , and the obtained raw foil is washed and dried to obtain electrolytic copper foil, specifically, water washing, acid washing, re-washing, polishing, and baking to obtain high-ductility electrolytic copper foil;

[0033] In the electrolyte:

[0034] Polyethylene glycol with a molecular weight of 3000 and a concentration of 5 mg / L;

[0035] Polyethyleneimine with a molecular weight of 10,000 and a concentration of 35 mg / L;

[0036] The concentration of hydroxypropyl methylcellulose is 8 mg / L;

[0037] Cu 2+ The concentration of nitric acid is 70g / L, and the concentration of sulfuric acid is 130g / L;

[0038] Chlorine compounds Cl - The concentration is 30 mg / L;

[0039] Graphene oxide concentration 8 mg / L;

[0040] Guar gum concentration 15 mg / L;

[0041] The gold concentration of potassium gold cyanide is 30 mg / L;

[0042] The platinum element concentration of platinum nitrate is 20 mg / L. Example

[0043] Add the additive to the sulfuric acid-copper sulfate solution as the electrolyte and conduct the electrolysis at 40℃ and 80A / dm 2 Electrolysis is performed at a current density of , and the obtained raw foil is washed and dried to obtain electrolytic copper foil, specifically, water washing, acid washing, re-washing, polishing, and baking to obtain high-ductility electrolytic copper foil;

[0044] In the electrolyte:

[0045] Polyethylene glycol with a molecular weight of 5000 and a concentration of 7 mg / L;

[0046] Polyethyleneimine with a molecular weight of 6000 and a concentration of 40 mg / L;

[0047] The concentration of hydroxypropyl methylcellulose was 13 mg / L;

[0048] Cu 2+ The concentration of nitric acid is 90g / L, and the concentration of sulfuric acid is 190g / L;

[0049] Chlorine compounds Cl - The concentration is 23 mg / L;

[0050] Graphene oxide concentration 3 mg / L;

[0051] Guar gum concentration 12 mg / L;

[0052] The gold concentration of potassium gold cyanide is 37 mg / L;

[0053] The platinum concentration of platinum nitrate is 23 mg / L. Example

[0054] Add additives to sulfuric acid-copper sulfate solution as electrolyte, at 45℃ and 40A / dm 2 Electrolysis is performed at a current density of , and the obtained raw foil is washed and dried to obtain electrolytic copper foil, specifically, water washing, acid washing, re-washing, polishing, and baking to obtain high-ductility electrolytic copper foil;

[0055] In the electrolyte:

[0056] Polyethylene glycol with a molecular weight of 4300 and a concentration of 9 mg / L;

[0057] Polyethyleneimine with a molecular weight of 5600 and a concentration of 28 mg / L;

[0058] The concentration of hydroxypropyl methylcellulose is 8 mg / L;

[0059] Cu 2+The concentration of nitric acid is 85g / L, and the concentration of sulfuric acid is 175g / L;

[0060] Chlorine compounds Cl - The concentration is 33 mg / L;

[0061] Graphene oxide concentration 5 mg / L;

[0062] Guar gum concentration 17 mg / L;

[0063] The gold concentration of potassium gold cyanide is 33 mg / L;

[0064] The platinum concentration of platinum nitrate is 45 mg / L. Example

[0065] Add additives to sulfuric acid-copper sulfate solution as electrolyte, at 45℃ and 40A / dm 2 Electrolysis is performed at a current density of , and the obtained raw foil is washed and dried to obtain electrolytic copper foil, specifically, water washing, acid washing, re-washing, polishing, and baking to obtain high-ductility electrolytic copper foil;

[0066] In the electrolyte:

[0067] Polyethylene glycol with a molecular weight of 4300 and a concentration of 4 mg / L;

[0068] Polyethyleneimine with a molecular weight of 5600 and a concentration of 20 mg / L;

[0069] The concentration of hydroxypropyl methylcellulose was 4 mg / L;

[0070] Cu 2+ The concentration of nitric acid is 40g / L, and the concentration of sulfuric acid is 100g / L;

[0071] Chlorine compounds Cl - The concentration is 10 mg / L;

[0072] Graphene oxide concentration 2 mg / L;

[0073] Guar gum concentration 10 mg / L;

[0074] The gold concentration of potassium gold cyanide is 20 mg / L;

[0075] The platinum element concentration of platinum nitrate is 20 mg / L. Example

[0076] Add additives to sulfuric acid-copper sulfate solution as electrolyte, at 65℃ and 45A / dm 2 Electrolysis is performed at a current density of , and the obtained raw foil is washed and dried to obtain electrolytic copper foil, specifically, water washing, acid washing, re-washing, polishing, and baking to obtain high-ductility electrolytic copper foil;

[0077] In the electrolyte:

[0078] Polyethylene glycol with a molecular weight of 8000 and a concentration of 10 mg / L;

[0079] Polyethyleneimine with a molecular weight of 10,000 and a concentration of 50 mg / L;

[0080] The concentration of hydroxypropyl methylcellulose is 20 mg / L;

[0081] Cu 2+ The concentration of nitric acid is 105g / L, and the concentration of sulfuric acid is 200g / L;

[0082] Chlorine compounds Cl - The concentration is 40 mg / L;

[0083] Graphene oxide concentration 8 mg / L;

[0084] Guar gum concentration 18 mg / L;

[0085] The gold concentration of potassium gold cyanide is 50 mg / L;

[0086] The platinum element concentration of platinum nitrate is 50 mg / L.

[0087] Comparative Example 1

[0088] The lithium battery copper foil was prepared by the same method as in Example 1, without adding potassium gold cyanide and platinum nitrate, and other components and data remained unchanged.

[0089] Comparative Example 2

[0090] The lithium battery copper foil was prepared by the same method as in Example 1, without adding platinum nitrate, and other components and data remained unchanged.

[0091] Comparative Example 3

[0092] The lithium battery copper foil was prepared by the same method as in Example 1, without adding potassium gold cyanide, and other components and data remained unchanged.

[0093] Experimental results: The content of each element in the electrolytic copper foil obtained in Examples 1-7 and Comparative Examples 1-3 was measured. The results are shown in the following table:

[0094] Group Copper content (wt%) Chlorine content (μg / g) Gold content (μg / g) Platinum content (μg / g) Example 1 99.94 156.48 5.3 153.9 Example 2 99.96 152.8 113.5 126.8 Example 3 99.95 178.3 162.6 91.8 Example 4 99.96 161.6 182.1 123.2 Example 5 99.94 181.3 173.6 190.7 Example 6 99.92 100.78 0.48 0.2 Example 7 99.98 199.3 199.6 199.8 Comparative Example 1 99.92 145.600 Comparative Example 2 99.94 152.99 0.20 Comparative Example 3 99.93 164.60 166.3

[0095] The tensile strength and elongation of the electrolytic copper foils prepared in Examples 1-7 and Comparative Examples 1-3 were tested. The test results are shown in the following table:

[0096] Group Tensile strength (MPa) Elongation (%) Resistivity (Ωm) Example 1 540 11.8 1.63*10^-8 Example 2 530 11.3 1.65*10^-8 Example 3 490 10.4 1.68*10^-8 Example 4 510 9.9 1.66*10^-8 Example 5 570 10.2 1.67*10^-8 Example 6 50 5 10.3 1.66*10^-8 Example 7 512 10.7 1.65*10^-8 Comparative Example 1 410 5.4 1.72*10^-8 Comparative Example 2 430 7.3 1.70*10^-8 Comparative Example 3 450 8.1 1.69*10^-8

[0097] From the table above, we can see that the current density is 40-80A / dm at a temperature of 40-65℃. 2 Under these conditions, the tensile strength and elongation of electrolytic copper foil prepared with gold and platinum additives are greatly improved, the electrical conductivity is reduced, and the electrical conductivity is improved.

Claims

1. An electrolytic copper foil comprising: a copper content of ≥99.9 wt %, a chlorine content of 100-200 μg / g, and further comprising: a gold content of 80-200 μg / g and a platinum content of 80-200 μg / g.

2. A method for preparing an electrolytic copper foil according to claim 1, comprising: Additives are added to a sulfuric acid-copper sulfate solution, which is used as an electrolyte for electrolysis, and the obtained raw foil is washed and dried to obtain the electrolytic copper foil; the additives include graphene oxide, guar gum, hydroxypropyl methylcellulose, polyethylene glycol, polyethyleneimine and a chlorine-containing compound, and the additives also include a soluble salt of gold and a soluble salt of platinum.

3. The preparation method according to claim 2, wherein The soluble salt of the gold element is selected from one or more of sodium chloroaurate and potassium gold cyanide.

4. The preparation method according to claim 2, wherein The soluble salt of the platinum element is selected from one or more of platinum acetate and platinum nitrate.

5. The preparation method according to claim 2, wherein In the electrolyte, Cu 2+ The concentration of sulfuric acid is 40-105 g / L, and the concentration of sulfuric acid is 100-200 g / L.

6. The preparation method according to claim 2, wherein In the electrolyte, the concentration of graphene oxide is 2-8 mg / L, the concentration of guar gum is 10-18 mg / L, the concentration of gold element is 20-50 mg / L, the concentration of platinum element is 20-50 mg / L, the concentration of hydroxypropyl methylcellulose is 4-20 mg / L, the concentration of polyethylene glycol is 4-10 mg / L, the concentration of polyethyleneimine is 20-50 mg / L, and the concentration of chlorine-containing compounds is 10-18 mg / L. - The concentration is 10-40 mg / L.

7. The preparation method according to claim 2, wherein The molecular weight of the polyethylene glycol is 3000-8000; the molecular weight of the polyethyleneimine is 5000-10000.

8. The preparation method according to claim 2, wherein During the electrolysis process, the temperature of the electrolyte is controlled at 40-65°C, and the average current density on the cathode electrode surface is 40-80A / dm 2 .

9. The preparation method according to claim 2, wherein The process of washing the raw foil includes multiple water washes, followed by washing with dilute hydrochloric acid, and then multiple water washes.

10. A lithium battery comprising the electrolytic copper foil according to claim 1 or the electrolytic copper foil prepared by the preparation method according to any one of claims 2 to 9.