Additive for electrolytic copper foil, electrolyte and application

Abstract

This invention belongs to the field of electrolytic copper foil production technology, specifically relating to an additive, electrolyte, and application for electrolytic copper foil. The additive includes sulfur-containing organic compounds, polyethylene glycol, and quaternary ammonium salt-modified polyetheramine. The quaternary ammonium salt-modified polyetheramine is prepared by a ring-opening grafting reaction between polyetheramine and 2,3-epoxypropyltrimethylammonium chloride. The electrolyte contains 70-100 g / L Cu. 2+ 90-150 g / L SO4 2‑ 15-30 mg / L Cl ‑ The additives and electrolyte of this invention utilize polyethylene glycol and quaternary ammonium salt-modified polyetheramine in combination, which can synergistically reduce the roughness of electrolytic copper foil and improve its mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of electrolytic copper foil production technology, specifically relating to an additive, electrolyte, and application for electrolytic copper foil. Background Technology

[0002] With the rapid development of the lithium battery industry, the technology of lithium batteries has gradually moved from low-end to high-end. In the process of technological development, low profile, high tensile strength, and ultra-thin electrolytic copper foil for lithium batteries are the mainstream direction of future research and development.

[0003] In the preparation of electrolytic copper foil, electrolyte additives have a crucial impact on its performance. Currently, the main electrolyte additives include sulfur-containing organic compounds, polyether organic compounds, and amine organic compounds. Sulfur-containing organic compounds primarily improve the surface gloss and roughness of the electrolytic copper foil through synergistic adsorption and complexation effects with chloride ions. Polyether organic compounds mainly act as wetting agents, adsorbing onto the metal surface to reduce interfacial surface tension, promoting the expulsion of gases generated by the hydrogen evolution side reaction, and preventing pinhole defects. Simultaneously, they inhibit abnormal copper deposition through steric hindrance effects, enhance cathodic polarization, and result in finer and denser copper foil crystals, thereby improving the mechanical properties of the electrolytic copper foil. The mechanism of action of amine organic compounds utilizes amino cations [NR4] during the electrolysis process. + Or it may accept hydrogen ions to form amino cations NH3. + An adsorption layer forms at the active sites on the electrode surface (generally raised areas with concentrated negative charges). This adsorption layer inhibits initial nucleation, suppressing deposition at these sites while allowing normal deposition at the recesses. This reduces the peak height and raises the valleys on the copper foil surface, macroscopically resulting in reduced profile undulation and surface roughness. Commonly used amine-based organic leveling agents include gelatin, collagen and other amino acid polymers, polyethyleneimine and its derivatives, and long-chain alkyl quaternary ammonium salts. However, the positions of active sites constantly change during copper deposition, necessitating effective additives for adsorption and desorption processes. While gelatin, collagen and other amino acid polymers, and polyethyleneimine and their derivatives can form good adsorption layers, their large molecular weight and high steric hindrance make desorption and migration difficult. This reduces the leveling effect and makes them prone to binding as adsorbed impurities into the deposit, lowering the mechanical strength of the copper foil. Long-chain alkyl quaternary ammonium salts, on the other hand, have a weaker adsorption layer formation ability due to their low amino ion density and few polar adsorption groups. In addition, existing amine-based organic leveling agents (especially long-chain alkyl quaternary ammonium salts) generally have poor compatibility with polyether-based organic wetting agents, and they are prone to competitive adsorption during electrolysis, making it difficult to achieve a synergistic improvement effect. Summary of the Invention

[0004] To address the aforementioned problems, the primary objective of this invention is to provide an additive for electrolytic copper foil. The additive of this invention utilizes a combination of polyethylene glycol and quaternary ammonium salt-modified polyetheramine, which synergistically reduces the roughness of electrolytic copper foil and improves its mechanical properties.

[0005] Another object of the present invention is to provide an electrolyte containing the above-mentioned additives.

[0006] Another object of the present invention is to provide the application of the above-mentioned electrolyte in the preparation of electrolytic copper foil.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] An additive for electrolytic copper foil comprises a sulfur-containing organic compound, polyethylene glycol, and a quaternary ammonium salt-modified polyetheramine, wherein the quaternary ammonium salt-modified polyetheramine has the following general chemical formula:

[0009] Cl - (CH3)3N + CH2(OH)CHCH2-(R3)N[CH2CH2O] x [CH2CH(CH3)O] y CH2CH(R1)N(R2)-CH2CH(OH)CH2N + (CH3)3Cl - ,

[0010] In the formula, x is an integer from 0 to 100, y is an integer from 0 to 100, and x + y ≥ 5; R1 is -H or -CH3, and R2 and R3 are the same or different -H or -CH2CH(OH)CH2N. + (CH3)3Cl - .

[0011] The quaternary ammonium salt modified polyetheramine can be a conventional industrial-grade polyetheramine (with the general molecular formula H2N[CH2CH2O)). x [CH2CH (CH3)O] y CH2CH(R1)NH2) and 2,3-epoxypropyltrimethylammonium chloride (molecular formula: It was obtained through a ring-opening grafting reaction.

[0012] As a general example, the preparation method of the quaternary ammonium salt modified polyetheramine is as follows:

[0013] Polyetheramine and 2,3-epoxypropyltrimethylammonium chloride were dissolved in an ethanol aqueous solution at a molar ratio of 1:2-4, and then heated to carry out a ring-opening grafting reaction. After the reaction was completed, the solvent was removed to obtain quaternary ammonium salt modified polyetheramine.

[0014] Preferably, the ethanol content of the aqueous ethanol solution is 75-90 wt%.

[0015] Preferably, the ring-opening grafting reaction is carried out at a temperature of 60-90°C for 2-5 hours. The reaction endpoint can be determined by measuring the ammonia and epoxy values ​​in the product.

[0016] Preferably, the sulfur-containing organic compound is one or more of thiourea, N-allyl thiourea, ethylene thiourea, sodium polydisulfide dipropane sulfonate, sodium allyl sulfonate, sodium dimethylformamidopropane sulfonate, and sodium 3-mercapto-1-propane sulfonate.

[0017] Preferably, the number average molecular weight of the polyethylene glycol is 1000-8000.

[0018] An electrolyte containing the above-mentioned additives.

[0019] Preferably, the electrolyte further includes copper sulfate, sulfuric acid, and a chloride ion source, wherein the chloride ion source is one or more of hydrogen chloride, sodium chloride, and potassium chloride.

[0020] Preferably, the electrolyte contains 70-100 g / L Cu. 2+ 90-150 g / L SO4 2- 15-30 mg / L Cl - 10-80 mg / L sulfur-containing organic matter, 2-20 mg / L polyethylene glycol, 1-10 mg / L quaternary ammonium salt modified polyetheramine.

[0021] The application of the above-mentioned electrolyte in the preparation of electrolytic copper foil, wherein the application method is as follows:

[0022] The electrolyte is introduced into the foil electrolytic cell at a flow rate of 40-70 m³ / h. 3 / h, current density 50-90A / dm 2 Electrodeposition was performed under specific conditions to obtain electrolytic copper foil.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] (1) The quaternary ammonium salt modified polyether amine end groups used in this invention contain multiple amino cations [NR4]. + Furthermore, the secondary or tertiary amines contained therein can further accept hydrogen ions to form amino cations during electrolysis, which can better form an adsorption layer at the active sites on the electrode surface, thereby significantly improving the leveling effect.

[0025] (2) The main chain of the quaternary ammonium salt modified polyetheramine used in this invention is a flexible polyether chain, which has good compatibility with polyethylene glycol wetting adsorbent. There is no competitive adsorption during the electrolysis process. It can be desorbed and migrated synchronously with the polyethylene glycol dynamic adsorption layer. While enhancing the cathode polarization effect, it can form an adsorption layer more uniformly on the active sites of the electrode surface, thereby synergistically improving the uniformity and smoothness of the coating. Detailed Implementation

[0026] The following specific examples illustrate embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments.

[0027] Example 1

[0028] An additive for electrolytic copper foil includes N-allyl thiourea, sodium polydithiopropane sulfonate, polyethylene glycol-4000, and quaternary ammonium salt modified polyetheramine (chemical formula: Cl). - (CH3)3N + CH2(OH)CHCH2-HN[CH2CH2O] x CH2CH2NH-CH2CH(OH)CH2N + (CH3)3Cl - The product was obtained by reacting industrial-grade amino-terminated polyethylene glycol (NH2-PEG-NH2) with 2,3-epoxypropyltrimethylammonium chloride at a molar ratio of 1:2 in an 80 wt% ethanol aqueous solution, heating to 75°C for 3 h, followed by vacuum solvent removal.

[0029] An electrolyte containing the above-mentioned additives, comprising the above-mentioned additives, copper sulfate, sulfuric acid, and hydrochloric acid. The amount of each material added is controlled to ensure that the electrolyte contains 80 g / L Cu. 2+ 110 g / L SO4 2- 20 mg / L Cl - 20 mg / L N-allyl thiourea, 20 mg / L sodium dithiodipropane sulfonate, 10 mg / L polyethylene glycol-4000, 8 mg / L quaternary ammonium salt modified polyetheramine.

[0030] The application of the above-mentioned electrolyte in the preparation of electrolytic copper foil is as follows:

[0031] The electrolyte is introduced into a foil electrolytic cell, which uses a titanium-coated roller as the cathode and a titanium-coated material as the anode. The electrolyte flow rate is 50 m³ / min. 3 / h, current density 60A / dm 2Electrodeposition was performed under specific conditions to obtain an ultrathin electrolytic copper foil with a target thickness of 6 μm.

[0032] Example 2

[0033] An additive for electrolytic copper foil includes sodium polydisulfide dipropane sulfonate, sodium allyl sulfonate, polyethylene glycol-4000, and quaternary ammonium salt modified polyetheramine (chemical formula: [Cl... - (CH3)3N + CH2(OH)CHCH2]2-N[CH2CH2O x CH2CH2NH-CH2CH(OH)CH2N + (CH3)3Cl - The product was obtained by reacting industrial-grade amino-terminated polyethylene glycol (NH2-PEG-NH2) with 2,3-epoxypropyltrimethylammonium chloride at a molar ratio of 1:3 in an 80 wt% ethanol aqueous solution, heating to 80 °C for 3 h, followed by vacuum solvent removal.

[0034] An electrolyte containing the above-mentioned additives, comprising the above-mentioned additives, copper sulfate, sulfuric acid, and hydrochloric acid. The amount of each material added is controlled to ensure that the electrolyte contains 70 g / L Cu. 2+ 90 g / L SO4 2- 15 mg / L Cl - 10 mg / L sodium dithiopropane sulfonate, 10 mg / L sodium allyl sulfonate, 5 mg / L polyethylene glycol-4000, 5 mg / L quaternary ammonium salt modified polyetheramine.

[0035] The application of the above-mentioned electrolyte in the preparation of electrolytic copper foil is as follows:

[0036] The electrolyte is introduced into a foil electrolytic cell, which uses a titanium-coated roller as the cathode and a titanium-coated material as the anode. The electrolyte flow rate is 70 m³ / min. 3 / h, current density 90A / dm 2 Electrodeposition was performed under specific conditions to obtain an ultrathin electrolytic copper foil with a target thickness of 6 μm.

[0037] Example 3

[0038] An additive for electrolytic copper foil includes sodium polydithiopropane sulfonate, polyethylene glycol-4000, and quaternary ammonium salt modified polyetheramine (chemical formula: [Cl... - (CH3)3N + CH2(OH)CHCH2]2-N[CH2CH2O x CH2CH2N-[CH2CH(OH)CH2N + (CH3)3Cl- 2. The product was obtained by reacting industrial-grade amino-terminated polyethylene glycol (NH2-PEG-NH2) with 2,3-epoxypropyltrimethylammonium chloride at a molar ratio of 1:4 in an 80 wt% ethanol aqueous solution, heating to 85°C for 3 h, and then removing the solvent under vacuum.

[0039] An electrolyte containing the above-mentioned additives, comprising the above-mentioned additives, copper sulfate, sulfuric acid, and hydrochloric acid. The amount of each material added is controlled to ensure that the electrolyte contains 90 g / L Cu. 2+ 130 g / L SO4 2- 25 mg / L Cl - 50 mg / L sodium dithiodipropane sulfonate, 15 mg / L polyethylene glycol-4000, 1 mg / L quaternary ammonium salt modified polyetheramine.

[0040] The application of the above-mentioned electrolyte in the preparation of electrolytic copper foil is as follows:

[0041] The electrolyte is introduced into a foil electrolytic cell, which uses a titanium-coated roller as the cathode and a titanium-coated material as the anode. The electrolyte flow rate is 60 m³ / min. 3 / h, current density 50A / dm 2 Electrodeposition was performed under specific conditions to obtain an ultrathin electrolytic copper foil with a target thickness of 6 μm.

[0042] Example 4

[0043] An additive for electrolytic copper foil includes N-allylthiourea, sodium 3-mercapto-1-propanesulfonate, polyethylene glycol-4000, and quaternary ammonium salt modified polyetheramine (chemical formula: Cl). - (CH3)3N + CH2(OH)CHCH2-HN[CH2CH(CH3)O] y CH2CH(CH3)NH-CH2CH(OH)CH2N + (CH3)3Cl - The product was obtained by reacting industrial-grade amino-terminated polypropylene glycol (NH2-PPG-NH2) with 2,3-epoxypropyltrimethylammonium chloride at a molar ratio of 1:2 in an 80 wt% aqueous ethanol solution, heating to 85°C for 3 h, followed by vacuum solvent removal.

[0044] An electrolyte containing the above-mentioned additives, comprising the above-mentioned additives, copper sulfate, sulfuric acid, and hydrochloric acid. The amount of each material added is controlled to ensure that the electrolyte contains 100 g / L Cu. 2+ 150 g / L SO4 2- 30 mg / L Cl -40 mg / L N-allyl thiourea, 20 mg / L sodium 3-mercapto-1-propanesulfonate, 20 mg / L polyethylene glycol-4000, 10 mg / L quaternary ammonium salt modified polyetheramine.

[0045] The application of the above-mentioned electrolyte in the preparation of electrolytic copper foil is as follows:

[0046] The electrolyte is introduced into a foil electrolytic cell, which uses a titanium-coated roller as the cathode and a titanium-coated material as the anode. The electrolyte flow rate is 40 m³ / min. 3 / h, current density 50A / dm 2 Electrodeposition was performed under specific conditions to obtain an ultrathin electrolytic copper foil with a target thickness of 6 μm.

[0047] Comparative Example 1

[0048] In this comparative example, gelatin was used to replace the quaternary ammonium salt modified polyetheramine in Example 1, and the rest were the same.

[0049] Comparative Example 2

[0050] In this comparative example, the additive used was hexadecyltrimethylammonium chloride, which replaced the quaternary ammonium salt modified polyetheramine in Example 1; otherwise, the additives were the same.

[0051] Comparative Example 3

[0052] In this comparative example, the additive used was a mixture of polyetheramine (industrial grade NH2-PEG-NH2 with a number average molecular weight of 3000) and hexadecyltrimethylammonium chloride (molar ratio of 1:2) to replace the quaternary ammonium salt modified polyetheramine in Example 1, and the rest were the same.

[0053] The ultrathin electrolytic copper foils obtained in the above embodiments and comparative examples were subjected to the following performance tests:

[0054] Roughness testing, the test method refers to IPC-TM-650 2.4.17;

[0055] For tensile strength and elongation testing, refer to IPC-TM-650 2.4.18 for the test method.

[0056] The corresponding test results are shown in Table 1 below:

[0057] Table 1 Comparison of the performance of ultrathin electrolytic copper foils obtained in Examples 1-4 and Comparative Examples 1-3

[0058] Test Example Surface roughness Rz / μm Tensile strength (at room temperature) / MPa Elongation (at room temperature) / % Example 1 1.0 672 8.5 Example 2 1.1 635 9.1 Example 3 1.5 594 6.6 Example 4 0.9 640 7.9 Comparative Example 1 2.4 495 8.1 Comparative Example 2 2.7 528 8.2 Comparative Example 3 1.8 536 8.2

[0059] The comparison results between Comparative Examples 1-2 and Example 1 in Table 1 show that the quaternary ammonium salt-modified polyetheramine of the present invention can significantly reduce the roughness and increase the tensile strength of copper foil compared with conventional amine organic compounds. This is because it can better synergize with the polyethylene glycol wetting adsorbent to improve the uniformity and smoothness of the coating. The results of Comparative Example 3 show that although the mixture of polyetheramine and hexadecyltrimethylammonium chloride can reduce roughness to some extent, the improvement effect is not as good as in Example 1, and the effect on improving tensile strength is not significant.

[0060] The above description, in conjunction with specific embodiments, further illustrates the present invention. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope thereof, but all such modifications and substitutions are included within the protection scope of the present invention.

Claims

1. An additive for electrolytic copper foil, characterized in that: It includes sulfur-containing organic compounds, polyethylene glycol, and quaternary ammonium salt-modified polyetheramines, wherein the quaternary ammonium salt-modified polyetheramines have the following general chemical formula: Cl - (CH3)3N + CH2(OH)CHCH2-(R3)N[CH2CH2O] x [CH2CH(CH3)O] y CH2CH(R1)N(R2)-CH2CH(OH)CH2N + (CH3)3Cl - , In the formula, x is an integer from 0 to 100, y is an integer from 0 to 100, and x + y ≥ 5; R1 is -H or -CH3, and R2 and R3 are the same or different -H or -CH2CH(OH)CH2N. + (CH3)3Cl - .

2. The additive for electrolytic copper foil according to claim 1, characterized in that: The preparation method of the quaternary ammonium salt modified polyetheramine is as follows: Polyetheramine and 2,3-epoxypropyltrimethylammonium chloride were dissolved in an ethanol aqueous solution at a molar ratio of 1:2-4, and then heated to carry out a ring-opening grafting reaction. After the reaction was completed, the solvent was removed to obtain quaternary ammonium salt modified polyetheramine.

3. The additive for electrolytic copper foil according to claim 2, characterized in that: The ethanol aqueous solution has an ethanol content of 75-90 vt.

4. The additive for electrolytic copper foil according to claim 2, characterized in that: The ring-opening grafting reaction is carried out at a temperature of 60-90℃ for 2-5 hours.

5. The additive for electrolytic copper foil according to claim 1, characterized in that: The sulfur-containing organic compound is one or more of thiourea, N-allyl thiourea, ethylene thiourea, sodium polydisulfide dipropane sulfonate, sodium allyl sulfonate, sodium dimethylformamidopropane sulfonate, and sodium 3-mercapto-1-propane sulfonate.

6. The additive for electrolytic copper foil according to claim 1, characterized in that: The number average molecular weight of the polyethylene glycol is 1000-8000.

7. An electrolyte containing the additive according to any one of claims 1-6.

8. The electrolyte according to claim 7, characterized in that: The electrolyte also includes copper sulfate, sulfuric acid, and a chloride ion source, wherein the chloride ion source is one or more of hydrogen chloride, sodium chloride, and potassium chloride.

9. An electrolyte according to claim 8, characterized in that: The electrolyte contains 70-100 g / L Cu 2 + 90-150 g / L SO4 2- 15-30 mg / L Cl - 10-80 mg / L sulfur-containing organic matter, 2-20 mg / L polyethylene glycol, 1-10 mg / L quaternary ammonium salt modified polyetheramine.

10. The application of the electrolyte according to any one of claims 7-9 in the preparation of electrolytic copper foil, characterized in that... The application method is as follows: The electrolyte is introduced into the foil electrolytic cell at a flow rate of 40-70 m³ / h. 3 / h, current density 50-90A / dm 2 Electrodeposition was performed under specific conditions to obtain electrolytic copper foil.