CN118028918A - A copper foil composite additive and a method for preparing a highly oriented electrolytic copper foil - Google Patents

Abstract

The invention discloses a copper foil composite additive and a method for preparing a crystal face highly oriented electrolytic copper foil, wherein the composite additive comprises the following components: an additive A, wherein the additive A is at least one of sulfonated thiacalix [4] arene, sulfonated thiacalix [6] arene and sulfonated thiacalix [8] arene; due to the rigid structure of the sulfonated thiacalixarene, the calixarene adsorbed on the cathode forms an oriented arrangement with the sulfonic acid groups upwards. The thiaaromatics can absorb water molecules in the hydrated copper ions by utilizing sulfonic acid groups and hydroxyl groups to obtain exposed copper ions. Copper ions entering the annular cavity through the upper edge can be complexed with the sulfur bridge bond of the calixarene, and the annular cavity at the lower edge of the calixarene is smaller, so that copper cannot be separated out on the cathode. Copper ions can only approach the cathode from the edge of calixarene, so that copper grains grow directionally, meanwhile, the overpotential for copper ion precipitation is increased, and according to the principle of lowest energy, the (111) crystal face precipitation of copper is facilitated, and the tensile strength of the copper foil is further improved.

Description

A copper foil composite additive and a method for preparing a highly oriented crystal surface electrolytic copper foil

Technical Field

The invention relates to the technical field of copper foil production, and more specifically to a copper foil composite additive and a method for preparing a crystal plane highly oriented electrolytic copper foil.

Background technique

In recent years, as the requirements for lithium batteries have become increasingly higher, higher requirements have been placed on the performance of lithium battery copper foil. For example, in response to the demand for high energy density, copper foil is required to be thinner on the one hand, so that the unit mass of copper foil has a larger area that can be coated with negative electrode materials; on the other hand, copper foil is required to coat more active materials on a fixed coating area. Copper foil coated with more negative electrode active materials needs to withstand greater pressure in the subsequent rolling step of the battery manufacturing process, so copper foil with high tensile strength is required.

Currently, sulfur-containing organic additives are commonly used as copper foil additives, such as sodium polydisulfide propane sulfonate, sodium 3-mercapto-1-propane sulfonate and thiourea, etc., which control the nucleation and growth rate of copper foil grains, thereby controlling the size of copper foil particles and the flatness of the copper foil surface, thereby controlling the tensile strength and elongation of copper foil. However, after these traditional additive raw materials are used to prepare additives, the tensile strength of copper foil is generally 320-370MPa, and the tensile strength needs to be improved.

According to literature records, the higher the proportion of (111) planes in copper foil grains, the higher the tensile strength of the copper foil. Therefore, an additive is developed that can effectively promote the highly oriented growth of the (111) planes of the copper foil, thereby achieving the production of high tensile strength copper foil.

Summary of the invention

In view of the problems existing in the prior art, the purpose of the present invention is to provide a composite additive, which is then mixed and added to the main electrolyte, thereby changing the microstructure and morphology of the coating by affecting the copper ion deposition reaction rate, thereby preparing a high tensile strength electrolytic copper foil.

In order to solve the above problems, the present invention adopts the following technical solutions: A composite additive for electrolytic copper foil, the composite additive comprising:

Additive A, wherein the additive A is at least one of sulfonated thiacalix[4]arene, sulfonated thiacalix[6]arene and sulfonated thiacalix[8]arene, as a brightener;

Additive B, as a wetting agent;

Additive C acts as a leveling agent.

Preferably, the additive B is at least one of ethylene glycol, polyoxyethylene ether, polyacrylamide and xanthan gum.

Preferably, the additive C is gelatin or collagen.

Preferably, in the additive B, the molecular weight of ethylene glycol is 6000-9000 Mw.

Preferably, in the additive C, the molecular weight of gelatin or collagen is 2000-5000Mw.

A method for preparing a high-tensile electrolytic copper foil comprises the following steps:

S1, preparation of electrolyte, adding metallic copper into a copper dissolving tank containing sulfuric acid, blowing air into it, and dissolving to obtain copper sulfate electrolyte;

S2, adding ammonium chloride in step S1 to obtain a main electrolyte;

S3, adding the composite additive in step S2;

S4, the electrolyte obtained in step S3 is transported to a foil machine to obtain copper foil.

Preferably, the temperature of the heat exchanger is set at 50-55°C, the flow rate is 46-58m ³ /h, and the current density is 40-46A/dm ² during the platinum production process.

Preferably, after completing step S, the concentration of the additive A in the electrolyte is 100-160 ppm; the concentration of the additive B in the electrolyte is 20-40 ppm; the concentration of the additive C in the electrolyte is 5-45 ppm; the copper ion concentration is 70-130 g/L, the hydrogen ion concentration is 80-130 g/L, and the chloride ion concentration is 15-35 ppm.

Preferably, the additive A, additive B and additive C are first stirred and dissolved at 50-55° C., and then added to the main electrolyte in sequence.

Preferably, the metallic copper is a metallic copper wire, the copper content of which is ≥99.5%, and the iron content of which is no more than 0.5%, and the thickness of the copper foil is 6 um.

Compared with the prior art, the present invention has the following beneficial effects:

Sulfonated sulfur calixarene, represented by water-soluble calixarene, has become a substitute for SPS sulfur-containing chemicals due to its strong inclusion coordination ability and good bonding selectivity for metals. Sulfonated sulfur calixarene can be adsorbed on the cathode surface using hydroxyl and sulfur functional groups, and the sulfonic acid anion at the other end adsorbs copper ions. Due to the rigid structure of sulfonated sulfur calixarene, the calixarene adsorbed on the cathode forms a directional arrangement with the sulfonic acid group facing upward. Sulfur calixarene can use sulfonic acid groups and hydroxyl groups to adsorb water molecules in hydrated copper ions to obtain naked copper ions. Copper ions entering the ring cavity through the upper edge will be complexed with the sulfur bridge bond of the calixarene, and the ring cavity at the lower edge of the calixarene is small, so that copper cannot be precipitated on the cathode. Copper ions can only approach the cathode from the edge of the calixarene, resulting in directional growth of copper grains. At the same time, the overpotential for copper ion precipitation increases. According to the principle of minimum energy, it is beneficial to the precipitation of copper (111) crystal plane, thereby improving the tensile strength of copper foil.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the adsorption of sulfonated thiacalix[4]arene on a titanium roller and the adsorption of metal ions.

FIG. 2 is a comparative characteristic diagram of Example 1 and Comparative Example 1 of the present invention.

Description of the numbers in the figure:

Detailed ways

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

In a first aspect, an embodiment of the present application provides a composite additive for electrolytic copper foil, the composite additive comprising: additive A, which is at least one of sulfonated thiacalix[4]arene, sulfonated thiacalix[6]arene and sulfonated thiacalix[8]arene, as a brightener; additive B, as a wetting agent; and additive C, as a leveling agent. It is understandable that additive A can be a single sulfonated thiacalix[4]arene, a single sulfonated thiacalix[6]arene, a single sulfonated thiacalix[8]arene; it can also be a mixture of sulfonated thiacalix[4]arene and sulfonated thiacalix[6]arene, a mixture of sulfonated thiacalix[4]arene and sulfonated thiacalix[8]arene, a mixture of sulfonated thiacalix[6]arene and sulfonated thiacalix[8]arene; it can also be a mixture of sulfonated thiacalix[4]arene, sulfonated thiacalix[6]arene and sulfonated thiacalix[8]arene.

In some embodiments, the additive B is at least one of ethylene glycol, polyoxyethylene ether, polyacrylamide, and xanthan gum. It is understandable that the additive B can be one of ethylene glycol, polyoxyethylene ether, polyacrylamide, and xanthan gum, or a mixture of ethylene glycol and polyoxyethylene ether, ethylene glycol and polyacrylamide, ethylene glycol and xanthan gum, polyoxyethylene ether and polyacrylamide, or a mixture of two or three thereof; or a mixture of all four of ethylene glycol, polyoxyethylene ether, polyacrylamide, and xanthan gum.

In some embodiments, the additive C is gelatin or collagen. It is understandable that, since collagen is an upgraded version of gelatin, the additive C is a single gelatin or a single collagen, and the two cannot be mixed for use.

In some embodiments, in the additive B, the molecular weight of ethylene glycol is 6000-9000Mw, for example: 6000Mw, 6500Mw, 7000Mw, 7500Mw, 8000Mw, 8500Mw, 9000Mw, etc.

In some embodiments, in the additive C, the molecular weight of gelatin or collagen is 2000-5000Mw, for example: 2000Mw, 2500Mw, 3000Mw, 3500Mw, 4000Mw, 4500Mw, 5000Mw, etc.

A second aspect of the embodiment of the present application provides a method for preparing a high tensile strength electrolytic copper foil, comprising the following steps:

S1, preparation of electrolyte, adding metallic copper into a copper dissolving tank containing sulfuric acid, blowing air into it, and dissolving to obtain copper sulfate electrolyte;

S2, adding ammonium chloride in step S1 to obtain a main electrolyte;

S3, adding the composite additive in step S2;

S4, the electrolyte obtained in step S3 is transported to a foil machine to obtain copper foil.

In some embodiments, during the platinum production process of the platinum production machine, the temperature of the heat exchanger is set to 50-55°C, for example, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, etc.; the delivery flow rate is 46-58m ³ /h, for example, 46m ³ /h, 47m ³ /h, 48m ³ /h, 49m ³ /h, 50m ³ /h, 51m ³ /h, 52m ³ /h, 53m ³ /h, 54m ³ /h, 55m ³ /h, 56m ³ /h, 57m ³ /h, 58m ³ /h, etc.; the current density is 40-46A/dm ² , for example, 40A/dm ² , 41A/dm ² , 42A/dm ² , 43A/dm ² , 44A/dm ² , 45A/dm ² , 46A/ ^dm2 , 47A/ ^dm2 , etc.

In some embodiments, after completing step S, the concentration of the additive A in the electrolyte is 100-160ppm; for example; 100ppm, 110ppm, 120ppm, 130ppm, 140ppm, 150ppm, 160ppm, etc. The concentration of the additive B in the electrolyte is 20-40ppm; for example: 20ppm, 25ppm, 30ppm, 35ppm, 40ppm, etc. The concentration of the additive C in the electrolyte is 5-45ppm; for example: 5ppm, 10ppm, 15ppm, 20ppm, 25ppm, 30ppm, 35ppm, 40ppm, 45ppm, etc. The copper ion concentration is 70-130g/L, for example: 70g/L, 80g/L, 90g/L, 100g/L, 110g/L, 120g/L, 130g/L, etc. The hydrogen ion concentration is 80-130 g/L, for example: 80 g/L, 90 g/L, 100 g/L, 110 g/L, 120 g/L, 130 g/L, etc. The chloride ion concentration is 15-35 ppm, for example: 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, etc.

In some embodiments, the additives A, B, and C are stirred and dissolved at 50-55° C., and then added to the main electrolyte in sequence. It is understandable that in order to ensure stability, before the additives A, B, and C are added to the main electrolyte, their temperatures need to be controlled to be the same as the temperature of the main electrolyte.

In some embodiments, the metal copper is a metal copper wire, and the copper content is ≥99.5%, for example: 99.5%, 99.6%, 99.7%, 99.8%, 100%. The iron content does not exceed 0.5%, for example: 0.5%, 0.4%, 0.3%, 0.2%, 0.1%, 0%. The thickness of the copper foil is 6um. It is understandable that the metal copper can also be a copper block, a copper rod, a copper sheet, etc.

Embodiment 1:

Metal copper is added into a copper dissolving tank containing sulfuric acid, air is blown in, and copper sulfate electrolyte is obtained by dissolving the metal copper. Ammonium chloride is then added to obtain a main electrolyte. Additive A (sulfonated thiacalix[4]arene), additive B (ethylene glycol), and additive C (gelatin) are stirred and dissolved at 50°C, and added into the main electrolyte in sequence. The concentrations of additive A, additive B, and additive C in the electrolyte are 100ppm, 20ppm, and 5ppm, respectively. The concentrations of copper ions, hydrogen ions, and chloride ions in the electrolyte are 70g/L, 80g/L, and 15ppm, respectively. Finally, the electrolyte is transported to a foil making machine. The heat exchanger temperature of the platinum making machine is set to 50°C, the transport flow rate is ^46m3 /h, and the current density is 40A/ ^dm2 , so as to obtain a copper foil with a thickness of 6um.

Embodiment 2:

Metal copper is added into a copper dissolving tank containing sulfuric acid, air is blown in, and copper sulfate electrolyte is obtained by dissolving. Ammonium chloride is then added to obtain a main electrolyte. Additive A sulfonated thiacalix[6]arene, additive B ethylene glycol, and additive C gelatin are stirred and dissolved at 51°C, and added to the main electrolyte in sequence. The concentrations of additive A, additive B, and additive C in the electrolyte are 110ppm, 20ppm, and 10ppm, respectively. The concentrations of copper ions, hydrogen ions, and chloride ions in the electrolyte are 80g/L, 90g/L, and 20ppm, respectively. Finally, the electrolyte is transported to a foil making machine. The heat exchanger temperature of the platinum making machine is set to 51°C, the transport flow rate is ^48m3 /h, and the current density is 42A/ ^dm2 , so as to obtain a copper foil with a thickness of 6um.

Embodiment 3:

Metal copper is added into a copper dissolving tank containing sulfuric acid, air is blown in, and copper sulfate electrolyte is obtained by dissolving the metal copper. Ammonium chloride is then added to obtain a main electrolyte. Additive A (sulfonated thiacalix[8]arene), additive B (ethylene glycol), and additive C (gelatin) are stirred and dissolved at 52°C, and added into the main electrolyte in sequence. The concentrations of additive A, additive B, and additive C in the electrolyte are 120ppm, 30ppm, and 15ppm, respectively. The concentrations of copper ions, hydrogen ions, and chloride ions in the electrolyte are 90g/L, 100g/L, and 25ppm, respectively. Finally, the electrolyte is transported to a foil making machine. The heat exchanger temperature of the platinum making machine is set to 52°C, the transport flow rate is ^50m3 /h, and the current density is 43A/ ^dm2 , so as to obtain a copper foil with a thickness of 6um.

Embodiment 4:

Metal copper is added into a copper dissolving tank containing sulfuric acid, air is blown in, and copper sulfate electrolyte is obtained by dissolving the metal copper. Ammonium chloride is then added to obtain a main electrolyte. Additive A, a mixture of sulfonated thiacalix[4]arene and sulfonated thiacalix[6]arene, additive B, a mixture of ethylene glycol and polyoxyethylene ether, and additive C, gelatin are stirred and dissolved at 53°C, and added into the main electrolyte in sequence. The concentrations of additive A, additive B, and additive C in the electrolyte are 130ppm, 35ppm, and 25ppm, respectively. The concentrations of copper ions, hydrogen ions, and chloride ions in the electrolyte are 100g/L, 110g/L, and 30ppm, respectively. Finally, the electrolyte is transported to a foil making machine. The heat exchanger temperature of the platinum making machine is set to 53°C, the transport flow rate is ^52m3 /h, and the current density is 44A/ ^dm2 , so as to obtain a copper foil with a thickness of 6um.

Embodiment 5:

Metal copper is added into a copper dissolving tank containing sulfuric acid, air is blown in, and copper sulfate electrolyte is obtained by dissolving. Ammonium chloride is then added to obtain a main electrolyte. Then, additive A, a mixture of sulfonated thiacalix [4]arene and sulfonated thiacalix [8]arene, additive B, a mixture of ethylene glycol, polyoxyethylene ether and polyacrylamide, and additive C, collagen are stirred and dissolved at 54° C., and added to the main electrolyte in sequence. The concentrations of additive A, additive B and additive C in the electrolyte are 140 ppm, 35 ppm and 35 ppm, respectively. The concentrations of copper ions, hydrogen ions and chloride ions in the electrolyte are 120 g/L, 120 g/L and 30 ppm, respectively. Finally, the electrolyte is transported to a foil making machine. The heat exchanger temperature of the platinum making machine is set to 54° C., the transport flow rate is 55 m ³ /h, and the current density is 45 A/dm ^2. A copper foil with a thickness of 6 um is obtained.

Embodiment 6:

Metal copper is added into a copper dissolving tank containing sulfuric acid, air is blown in, and copper sulfate electrolyte is obtained by dissolving the metal copper into the copper dissolving tank, and ammonium chloride is added to obtain a main electrolyte. Then, an agent A, a mixture of sulfonated thiacalix [4]arene, sulfonated thiacalix [6]arene and sulfonated thiacalix [8]arene, an additive B, a mixture of ethylene glycol and polyoxyethylene ether, polyacrylamide and xanthan gum, and an additive C, collagen are stirred and dissolved at 55° C., and added into the main electrolyte in sequence, and the concentrations of the additive A, additive B and additive C in the electrolyte are 160 ppm, 40 ppm and 45 ppm respectively. The concentrations of copper ions, hydrogen ions and chloride ions in the electrolyte are 130 g/L, 130 g/L and 35 ppm respectively. Finally, the electrolyte is transported to a foil making machine, the heat exchanger temperature of the platinum making machine is set to 55° C., the transport flow rate is 58 m ³ /h, and the current density is 46 A/dm ² , to obtain a copper foil with a thickness of 6 um.

Referring to Figure 1, due to the rigid structure of sulfonated thiacalixarene, the thiacalixarene adsorbed on the cathode forms a directional arrangement with the sulfonic acid group facing upward. The thiacalixarene can use the sulfonic acid group and the hydroxyl group to adsorb the water molecules in the hydrated copper ions to obtain naked copper ions. The copper ions that enter the ring cavity through the upper edge will be complexed with the sulfur bridge bond of the thiacalixarene, and the ring cavity at the lower edge of the thiacalixarene is small, so that copper cannot be precipitated on the cathode. The copper ions can only approach the cathode from the edge of the thiacalixarene, resulting in the directional growth of copper grains. At the same time, the overpotential of copper ion precipitation increases. According to the minimum energy principle, it is beneficial to the precipitation of copper on the (111) crystal plane.

Comparative Example 1:

Metal copper is added into a copper dissolving tank containing sulfuric acid, air is blown in, and copper sulfate electrolyte is obtained by dissolving. Ammonium chloride is then added to obtain a main electrolyte. SPS as a brightener, ethylene glycol as an additive B, and gelatin as an additive C are stirred and dissolved at 50°C, and added to the main electrolyte in sequence. The concentrations of SPS brightener, additive B, and additive C in the electrolyte are 100ppm, 20ppm, and 5ppm, respectively. The concentrations of copper ions, hydrogen ions, and chloride ions in the electrolyte are 70g/L, 80g/L, and 15ppm, respectively. Finally, the electrolyte is transported to a foil making machine, the heat exchanger temperature of the platinum making machine is set to 50°C, the transport flow rate is ^46m3 /h, and the current density is 40A/ ^dm2 , so as to obtain a copper foil with a thickness of 6um.

Referring to Figure 2, Comparative Example 1 is the trend curve No. 1 of Figure 2; Example 1 is the trend curve No. 2 of Figure 2. The characteristic peak height ratios I(111)/I(220) of samples No. 1 and No. 2 are 1.748 and 1.618, respectively, indicating that the use of sulfonated thiacalix[4]arene promotes the secondary orientation growth of copper grains inside the copper foil and improves the crystallization degree of copper grains. The more (111) crystal planes in the copper grains, the higher the tensile strength of the copper foil.

The lithium battery copper foil prepared by the electrolytic copper foil composite additive used in the present invention has the advantages of high tensile strength and uniform thickness. It has been measured that the tensile strength is ≥680Mpa under 3% elastic deformation at room temperature, and the tensile strength of the copper foil is ≥450Mpa after baking at 300°C under nitrogen protection for 16 hours.

The above is only a preferred specific implementation of the present invention; however, the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solution and its improved conception within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims (10)

1. An electrolytic copper foil composite additive, the composite additive comprising: Additive A, wherein the additive A is at least one of sulfonated thiacalix[4]arene, sulfonated thiacalix[6]arene and sulfonated thiacalix[8]arene, as a brightener; Additive B, as a wetting agent; Additive C acts as a leveling agent. 2. The electrolytic copper foil additive according to claim 1, characterized in that the additive B is at least one of ethylene glycol, polyoxyethylene ether, polyacrylamide, and xanthan gum. 3. The electrolytic copper foil additive according to claim 1, characterized in that the additive C is gelatin or collagen. 4. The electrolytic copper foil additive according to claim 2, characterized in that the molecular weight of ethylene glycol in the additive B is 6000-9000Mw. 5. The electrolytic copper foil additive according to claim 3, characterized in that: in the additive C, the molecular weight of gelatin or collagen is 2000-5000Mw. 6. A method for preparing a highly oriented electrolytic copper foil, characterized in that the electrolytic copper foil additive according to any one of claims 1 to 5 is used, comprising the following steps: S1, preparation of electrolyte, adding metallic copper into a copper dissolving tank containing sulfuric acid, blowing air into it, and dissolving to obtain copper sulfate electrolyte; S2, adding ammonium chloride in step S1 to obtain a main electrolyte; S3, adding the composite additive in step S2; S4, the electrolyte obtained in step S3 is transported to a foil machine to obtain copper foil. 7. A method for preparing a highly oriented electrolytic copper foil according to claim 6, characterized in that: during the platinum production process of the platinum production machine, the heat exchanger temperature is set to 50-55°C, the delivery flow is ^46-58m3 /h, and the current density is 40-46A/ ^dm2 8. A method for preparing a highly oriented electrolytic copper foil according to claim 6, characterized in that: after completing step S, the concentration of the additive A in the electrolyte is 100-160 ppm; the concentration of the additive B in the electrolyte is 20-40 ppm; the concentration of the additive C in the electrolyte is 5-45 ppm; the copper ion concentration is 70-130 g/L, the hydrogen ion concentration is 80-130 g/L, and the chloride ion concentration is 15-35 ppm. 9. A method for preparing a highly oriented electrolytic copper foil according to claim 6, characterized in that the additive A, additive B and additive C are first stirred and dissolved at 50-55°C, and then added to the main electrolyte in sequence. 10. A method for preparing a highly oriented electrolytic copper foil according to claim 6, characterized in that: the metal copper is a metal copper wire, the copper content is ≥99.5%, and the iron content does not exceed 0.5%, and the thickness of the copper foil is 6um.