CN114808046A - High-tensile-strength copper foil and preparation method thereof - Google Patents
High-tensile-strength copper foil and preparation method thereof Download PDFInfo
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- CN114808046A CN114808046A CN202210427872.0A CN202210427872A CN114808046A CN 114808046 A CN114808046 A CN 114808046A CN 202210427872 A CN202210427872 A CN 202210427872A CN 114808046 A CN114808046 A CN 114808046A
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims abstract description 118
- 239000011889 copper foil Substances 0.000 title claims abstract description 115
- 238000002360 preparation method Methods 0.000 title abstract description 10
- 239000003792 electrolyte Substances 0.000 claims abstract description 125
- PDQAZBWRQCGBEV-UHFFFAOYSA-N Ethylenethiourea Chemical compound S=C1NCCN1 PDQAZBWRQCGBEV-UHFFFAOYSA-N 0.000 claims abstract description 85
- 238000009713 electroplating Methods 0.000 claims abstract description 50
- 239000013078 crystal Substances 0.000 claims abstract description 34
- 238000000034 method Methods 0.000 claims abstract description 32
- 239000000654 additive Substances 0.000 claims abstract description 23
- 230000000996 additive effect Effects 0.000 claims abstract description 19
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 19
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 8
- 239000011593 sulfur Substances 0.000 claims abstract description 8
- 239000000243 solution Substances 0.000 claims description 24
- 239000011888 foil Substances 0.000 claims description 18
- 229910000365 copper sulfate Inorganic materials 0.000 claims description 17
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 claims description 17
- 239000010949 copper Substances 0.000 claims description 15
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 14
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 14
- 238000005868 electrolysis reaction Methods 0.000 claims description 14
- 238000005303 weighing Methods 0.000 claims description 13
- 238000004519 manufacturing process Methods 0.000 claims description 12
- 238000002156 mixing Methods 0.000 claims description 11
- 238000001179 sorption measurement Methods 0.000 claims description 11
- 239000011259 mixed solution Substances 0.000 claims description 8
- 239000002659 electrodeposit Substances 0.000 claims description 7
- 238000004070 electrodeposition Methods 0.000 claims description 7
- 238000002347 injection Methods 0.000 claims description 7
- 239000007924 injection Substances 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 125000004122 cyclic group Chemical group 0.000 claims description 5
- 239000002994 raw material Substances 0.000 claims description 3
- 230000002195 synergetic effect Effects 0.000 abstract description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 9
- 229910001416 lithium ion Inorganic materials 0.000 description 9
- 238000007747 plating Methods 0.000 description 9
- 230000000694 effects Effects 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 238000000151 deposition Methods 0.000 description 5
- 230000008021 deposition Effects 0.000 description 5
- 238000009864 tensile test Methods 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 238000001914 filtration Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 230000001965 increasing effect Effects 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 150000002500 ions Chemical group 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 description 1
- 239000005909 Kieselgur Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 239000003463 adsorbent Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- OJIJEKBXJYRIBZ-UHFFFAOYSA-N cadmium nickel Chemical compound [Ni].[Cd] OJIJEKBXJYRIBZ-UHFFFAOYSA-N 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 229910001431 copper ion Inorganic materials 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D1/00—Electroforming
- C25D1/04—Wires; Strips; Foils
Abstract
The invention discloses a copper foil with high tensile strength, which has the tensile strength of more than 800 MPa; the microstructure of the copper foil along the growth direction contains 2 types of large crystal grains and small crystal grains with different sizes, and the inside of the large crystal grains contains a nanometer twin crystal structure; the large and small crystal grains mutually surround to form a topological arrangement structure, and the density is more than 99.99%; and the crystal grains of the copper foil contain sulfur doping atoms, and the doping concentration is 5-50 ppm. The invention also discloses a preparation method of the copper foil with high tensile strength, which adopts an electrolytic method, and adopts an additive which simultaneously contains ethylene thiourea decomposition products and ethylene thiourea in electrolyte. The ethylene thiourea decomposition product is obtained by circulating electroplating: and (3) carrying out circulating electroplating by using the initial electrolyte, and forming the ethylene thiourea decomposition product when the circulating amount reaches more than or equal to 10 times of the initial electrolyte amount. The preparation method utilizes the coexistence of ethylene thiourea decomposition products and ethylene thiourea in the process of electrodepositing the copper foil to play a synergistic action to improve the tensile strength of the copper foil.
Description
Technical Field
The invention relates to the field of copper foil, and relates to an electrolytic copper foil with high tensile strength and a preparation method thereof.
Technical Field
The electrolytic copper foil has excellent heat conductivity and low resistance, and meanwhile, the manufacturing technology is mature, the yield is high, and the cost is low, so that the electrolytic copper foil is a basic functional material of the lithium ion battery in the new energy industry. Compared with the conventional alkaline battery, nickel-cadmium battery and nickel-hydrogen battery, the lithium ion battery has the advantages of small volume, light weight, high energy density, long service life, high charging speed, designable form and the like, so that the lithium ion battery becomes the preferred power supply of electronic products, electric tools and power automobiles in recent years, and the lithium ion battery industry also develops into a high and new technology industry which is mainly supported in the energy field of China. The copper foil plays the roles of a negative current collector and an active material carrier in the lithium ion battery, compared with the application scene of the copper foil in the traditional printed circuit board, the cyclic charge-discharge environment of the battery puts higher requirements on the roughness and the mechanical property of the copper foil, and the mass of the copper foil is as small as possible in the whole quality of the battery. With the development of lithium ion battery products toward high safety, high reliability, high power density and low cost, the copper foil for lithium ion batteries tends to be developed toward high performance, low thickness and low cost.
As the copper foil thickness continues to decrease, the strength of the copper foil is required to increase to offset the adverse effects of the decreasing cross-sectional area in order to meet the tension levels during application. Therefore, the development of high tensile strength copper foil is urgently needed to meet the development of lithium ion batteries. Although more technical schemes are provided for regulating and controlling the tissue morphology, structure and density of the copper foil in the electrolytic process by using various additives so as to improve the tensile strength of the copper foil, the research on the aspect is still immature, and a copper foil with extremely high tensile strength and a corresponding preparation technology thereof are still lacked.
Disclosure of Invention
The invention aims to provide a high-tensile copper foil and a preparation method thereof, aiming at the problem that the existing copper foil is not high enough in tensile strength.
The copper foil disclosed by the invention has the tensile strength of more than 800 MPa, and the microstructure of the copper foil along the growth direction (namely the thickness direction) has the following characteristics: (1) the microstructure comprises 2 types of crystal grains with different sizes, one type is large crystal grains with the size of 500-1000 nm and a nanometer twin structure in the interior, and the other type is small crystal grains with the size of 50-100 nm; (2) the large grains and the small grains in the microstructure are mutually surrounded, namely, a plurality of small grains are arranged around the large grains, and meanwhile, large grains are arranged around the small grains to form a topological arrangement structure; (3) the density is more than 99.99%; (4) the crystal grains contain sulfur doping atoms, and the doping concentration is 5-50 ppm.
The invention also discloses a preparation method of the copper foil with high tensile strength, which adopts an electrolytic method, namely an electrodeposition method, in the preparation method, the electrolyte contains an additive, and the additive contains ethylene thiourea decomposition products and ethylene thiourea.
Wherein the concentration of the ethylene thiourea in the electrolyte is as follows: 0.5-15mg/L is maintained by continuous addition during electrolysis.
The ethylene thiourea decomposition product is obtained by cyclic electroplating, and the method for obtaining the ethylene thiourea decomposition product by cyclic electroplating comprises the following steps: and (3) carrying out circulating electroplating by adopting an initial electrolyte, wherein when the circulating amount of the initial electrolyte reaches more than or equal to 10 times of the amount of the initial electrolyte, the ethylene thiourea decomposition product formed in the process is the ethylene thiourea decomposition product. Wherein the initial electrolyte contains an additive ethylene thiourea with the concentration of 0.5-15 mg/L.
Wherein, the electrolyte continuously meets the following requirements by supplementing copper sulfate in the electrolytic process: cu 2+ The concentration of (A) is 60-120g/L, H 2 SO 4 The concentration is 60-110g/L, Cl - The concentration is 10-30 mg/L.
More specifically, the invention also discloses the specific steps of the electrolytic preparation method, wherein the electrolytic deposition adopts an electrolytic circulating system which does not comprise a filter with adsorption capacity. The method at least comprises the following steps:
(1) preparing an initial electrolyte: weighing appropriate amount of copper sulfate, sulfuric acid and hydrochloric acid to form a mixed solution, wherein Cu in the mixed solution 2+ The concentration of (A) is 60-120g/L, H 2 SO 4 The concentration is 60-110g/L, Cl - The concentration is 10-30 mg/L; simultaneously weighing a proper amount of ethylene thiourea and dissolving the ethylene thiourea in water to obtain an ethylene thiourea solution; mixing the ethylene thiourea solution with the mixed solution according to the proportion of 1: 1000 volume ratio is mixed in an electrolytic tank to form initial electrolyte, wherein the concentration of ethylene thiourea in the initial electrolyte is 0.5-15mg/L, an electrolysis circulating system and a heater are started, and the temperature of the initial electrolyte is kept at 40-60 ℃.
(2) Pre-electroplating: connecting a power supply, enabling a foil generator to electrodeposit the copper foil in the electrolytic bath, keeping the initial electrolyte circulation, and performing pre-electroplating. And calculating the initial circulating amount of the electrolyte from the beginning of electrifying to deposit the copper foil, stopping the pre-electroplating when the initial circulating amount of the electrolyte is 10 times of the initial circulating amount of the electrolyte, and discarding the copper foil obtained by the pre-electroplating.
Since the electrolytic circulation system does not comprise a filter with adsorption capacity, a part of ethylene thiourea is converted into an electrolytic product during the pre-plating period, so that a certain concentration of ethylene thiourea decomposition product is obtained in the initial electrolyte at the end of the pre-plating.
(3) Electroplating of copper foil with high tensile strength: after the pre-electroplating is stopped, ethylene thiourea and copper sulfate are supplemented in the initial electrolyte to form an electrolyte II, so that the electrolyte II meets the following requirements: cu 2+ The concentration of (A) is 60-120g/L, H 2 SO 4 The concentration is 60-110g/L, Cl - The concentration is 10-30mg/L, the concentration of ethylene thiourea is 0.5-15mg/L, the electrolytic circulation system, the heater and the electroplating power supply are restarted, and electroplating is started; and in the electroplating process, the injection of ethylene thiourea and copper sulfate is continuously kept, so that the electrolyte continuously meets the following conditions: cu (copper) 2+ The concentration of (A) is 60-120g/L, H 2 SO 4 The concentration is 60-110g/L, Cl - The concentration is 10-30mg/L, the concentration of ethylene thiourea is 0.5-15mg/L, and the temperature of the electrolyte is kept at 40-60 ℃. And collecting the copper foil produced by the foil forming machine at the stage, namely the copper foil with high tensile strength. Because the electrolysis circulating system does not comprise a filter with adsorption capacity, the ethylene thiourea decomposition product newly formed in the electroplating process can be continuously supplemented into the electrolyte II, and coexists with the ethylene thiourea in the copper foil electrodeposition process, and the ethylene thiourea and the electrolyte II play a synergistic role in improving the tensile strength of the copper foil.
After extensive research, the inventors of the present invention found that ethylene thiourea is electrochemically oxidized during electrodeposition of a copper foil to form ethylene thiourea decomposition products, which can further improve the tensile strength of the copper foil. When ethylene thiourea decomposition products and ethylene thiourea coexist in the process of electrodepositing the copper foil, the copper foil structure can be more compact, and two types of crystal grains appear in the structure. One is large crystal grains with the size of 500-1000 nm and the inside of the large crystal grains contains a nanometer twin structure, and the other is small crystal grains with the size of 50-100 nm. And the large grains and the small grains are mutually surrounded in the structure, namely, a plurality of small grains are arranged around the large grains, and meanwhile, large grains are arranged around the small grains to form a topological arrangement structure. The texture structure ensures that the density of the copper foil is more than 99.99 percent, and holes or pinholes are hardly generated. And the crystal grains contain sulfur doping atoms, and the doping concentration is 5-50 ppm.
Although the electrolytic products are regarded as substances harmful to the production in the conventional concept of electrodeposited copper foil, they must be removed by various filtering means with the use of strong gas. However, the inventors have surprisingly found that the above topology and sulfur doping effects can be produced when the electrolysis product of ethylenethiourea is used in combination with ethylenethiourea. The topological structure enables the large and small crystal grains in the structure to be arranged in a coordinated manner, improves the density and avoids the defect that pinholes are easy to generate due to simple arrangement of the small crystal grains. Meanwhile, the large and small crystal grains are arranged in a coordinated manner, so that dislocation sliding resistance is increased, a twin crystal strengthening effect in the large crystal grains is superposed, and the effect of improving the dislocation sliding lattice friction force by doping sulfur elements is achieved, so that the copper foil has excellent tensile strength.
In order to obtain the above effect, it is necessary to intentionally produce a waste foil for a certain period of time in the process of preparing a copper foil as a pre-plating stage during which a part of ethylenethiourea is converted into an electrolytic product. At the same time, filters with adsorption are deliberately omitted in order to retain these electrolysis products, so that these electrolysis products can be recirculated back to the electrolysis cell. This is an important difference from the conventional electrolytic copper foil manufacturing apparatus, which often includes more than one filtering and adsorbing device for removing the electrolysis products of the additives and the surplus additives. The inventors have further found that when the circulating amount of the electrolyte is equal to 10 times the total amount of the electrolyte, the ethylene thiourea electrolytic product has a sufficient concentration to exert the synergistic effect of increasing the tensile strength of the copper foil, and the increasing effect becomes stable after a small increase with the increase of the circulating amount of the electrolyte (i.e., the foil forming time). When the circulating amount of the electrolyte is equal to 10 times of the total amount of the electrolyte, if only the concentration and acidity of copper ions are supplemented in the subsequent foil generation process, and ethylene thiourea is not supplemented, the strength of the produced copper foil tends to be stable after being gradually reduced. This also illustrates that it is difficult to obtain a high tensile strength copper foil by using only the ethylene thiourea electrolysis product or by using only ethylene thiourea, and organic combination of the two is required.
The waste foil produced during pre-plating can be replenished back to the production process by the copper dissolving device, thus saving cost without wasting raw materials except for some electric energy loss.
Compared with the prior art, the invention has the following beneficial effects:
(1) the invention provides a copper foil with high tensile strength, which has the characteristic of high tensile strength, so that the copper foil can meet the urgent requirements of the lithium ion battery industry on further reducing the thickness of the copper foil without influencing the production tension and speed.
(2) The invention also provides a method for preparing the copper foil, and the copper foil with high tensile strength can be prepared in a large scale by the method, so that the continuous development of the new energy field is promoted.
(3) According to the technical scheme, various additives are not needed, and only the ethylene thiourea is purchased from raw materials and added as the additive, so that the production controllability is greatly improved.
(4) According to the technical scheme, the synergistic enhancement effect of the ethylene thiourea electrolysis product and the ethylene thiourea is ingeniously utilized, a complicated filtering and adsorbing device is not needed, the production device is simplified, and the cost for maintaining the filtering and adsorbing device is avoided.
Drawings
Fig. 1 is a scanning electron micrograph of a cross section of the high tensile copper foil obtained in example 1.
Fig. 2 is a tensile stress strain curve of the copper foil of example 1, which was sampled and tested at the time when the circulating amount of the electrolyte was 1 time, 10 times, 20 times and 50 times the total amount of the electrolyte, respectively.
Detailed Description
The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.
Example 1
(1) Configuration ofAn electrolyte; weighing appropriate amount of copper sulfate, sulfuric acid and hydrochloric acid to prepare electrolyte, so that Cu in the electrolyte 2+ Has a concentration of 60g/L, H 2 SO 4 Concentration 60g/L, Cl - The concentration was 10 mg/L.
(2) Preparing an additive solution: weighing a proper amount of ethylene thiourea and dissolving the ethylene thiourea in water to obtain an ethylene thiourea solution.
(3) Circulating electrolyte: mixing the prepared additive solution and electrolyte according to the ratio of 1: mixing and injecting the mixture into an electrolytic tank at a volume ratio of 1000 to ensure that the concentration of ethylene thiourea in the mixed solution is 0.5mg/L, and starting an electrolyte circulating system and a heater to keep the temperature of the electrolyte at 60 ℃. The circulation system does not contain a filter having an adsorption capacity.
(4) Pre-electroplating: and connecting a power supply to ensure that the foil generator electrodeposits the copper foil in the electrolytic bath and keeps the electrolyte circulating. And calculating the circulating amount of the electrolyte from the beginning of electrifying the copper foil for deposition, and discarding the copper foil obtained by electroplating when the circulating amount of the electrolyte is less than 10 times of the total amount of the electrolyte.
(5) Formal electroplating: when the circulating amount of the electrolyte is equal to 10 times of the total amount of the electrolyte, the beginning stage of the formal electroplating is set. During the process, the continuous injection of the high-concentration ethylene thiourea solution and the high-concentration copper sulfate solution is kept, so that the Cu in the electrolytic cell is ensured 2+ Has a concentration of 60g/L, H 2 SO 4 Concentration of 60g/L, Cl - The concentration is 10mg/L, and the concentration of ethylene thiourea is 0.5 mg/L. And collecting the copper foil produced by the foil forming machine at the stage.
A scanning electron microscope is adopted to observe the cross section of the copper foil, as shown in figure 1, the topological structure characteristic that the internal structure of the copper foil is mutually surrounded by large and small crystal grains and is organically nested and distributed can be seen, and meanwhile, the straight twin boundary of the nanometer twin crystal structure in the large crystal grains can be seen. Wherein the large crystal grain size is 500-1000 nm, and the small crystal grain size is 50-100 nm. The content of sulfur element in the crystal grain is tested to be 5 ppm by adopting a flight time secondary ion mass spectrometer. The copper foil is very compact and almost has no holes or pinholes, and the density test result shows that the density of the copper foil is more than 99.99 percent.
An electronic tensile testing machine is adopted to test the tensile stress-strain curves of the copper foil obtained in different stages in the example 1, and as shown in the attached figure 2, when the circulation volume of the electrolyte is only 1 time of the total volume of the electrolyte, the strength of the copper foil is low; with the continuous proceeding of the electrodeposition process, the strength of the copper foil is remarkably improved to 800 MPa and then becomes gentle. In other examples, results consistent with example 1 were obtained.
Example 2
(1) Preparing electrolyte; weighing appropriate amount of copper sulfate, sulfuric acid and hydrochloric acid to prepare electrolyte, so that Cu in the electrolyte 2+ Has a concentration of 120g/L, H 2 SO 4 Concentration of 110g/L, Cl - The concentration was 30 mg/L.
(2) Preparing an additive solution: weighing a proper amount of ethylene thiourea, and dissolving the ethylene thiourea in water to obtain an ethylene thiourea solution.
(3) Circulating electrolyte: mixing the prepared additive solution and electrolyte according to the ratio of 1: mixing and injecting the mixture into an electrolytic tank at a volume ratio of 1000 to ensure that the concentration of ethylene thiourea in the mixture is 15mg/L, starting an electrolyte circulating system and a heater to ensure that the temperature of the electrolyte is kept at 40 ℃. The circulation system does not contain a filter having an adsorption capacity.
(4) Pre-electroplating: and connecting a power supply to ensure that the foil generator electrodeposits the copper foil in the electrolytic bath and keeps the electrolyte circulating. And calculating the circulating amount of the electrolyte from the beginning of electrifying the copper foil for deposition, and discarding the copper foil obtained by electroplating when the circulating amount of the electrolyte is less than 10 times of the total amount of the electrolyte.
(5) Formal electroplating: when the circulating amount of the electrolyte is equal to 10 times of the total amount of the electrolyte, the beginning stage of the formal electroplating is set. During the process, the continuous injection of the high-concentration ethylene thiourea solution and the high-concentration copper sulfate solution is kept, so that the Cu in the electrolytic cell is ensured 2+ Has a concentration of 120g/L, H 2 SO 4 Concentration of 110g/L, Cl - The concentration is 30mg/L, and the concentration of ethylene thiourea is 15 mg/L. And collecting the copper foil produced by the foil forming machine at the stage.
The observation result of a scanning electron microscope of the cross section of the copper foil shows that the copper foil has the same micro morphology as that of the copper foil in the embodiment 1, and the topological structure of the micro internal structure is characterized by organically nested distribution of large and small crystal grains. The content of sulfur element in the crystal grain was measured to be 50 ppm by a time-of-flight secondary ion mass spectrometer. The density test result shows that the density of the copper foil is more than 99.99 percent.
And (3) testing the copper foil in the formal electroplating stage by using an electronic tensile testing machine, wherein the result shows that the tensile strength of the copper foil reaches 825 MPa.
Comparative example 1
(1) Preparing electrolyte; weighing appropriate amount of copper sulfate, sulfuric acid and hydrochloric acid to prepare electrolyte, so that Cu in the electrolyte 2+ Has a concentration of 120g/L, H 2 SO 4 Concentration of 110g/L, Cl - The concentration was 30 mg/L.
(2) Preparing an additive solution: weighing a proper amount of ethylene thiourea, and dissolving the ethylene thiourea in water to obtain an ethylene thiourea solution.
(3) Circulating electrolyte: mixing the prepared additive solution and electrolyte according to the ratio of 1: mixing and injecting the mixture into an electrolytic tank at a volume ratio of 1000 to ensure that the concentration of ethylene thiourea in the mixture is 15mg/L, starting an electrolyte circulating system and a heater to ensure that the temperature of the electrolyte is kept at 40 ℃. The circulation system includes a filter having an adsorption capacity, and the filter contains an adsorbent such as diatomaceous earth or activated carbon.
(4) Pre-electroplating: and connecting a power supply to ensure that the foil generator electrodeposits the copper foil in the electrolytic bath and keeps the electrolyte circulating. Calculating the circulation amount of the electrolyte from the beginning of the copper foil through electrodeposition, and discarding the copper foil obtained by electroplating when the circulation amount of the electrolyte is less than 10 times of the total amount of the electrolyte.
(5) Formal electroplating: when the circulating amount of the electrolyte is equal to 10 times of the total amount of the electrolyte, the beginning stage of the formal electroplating is set. During the process, the continuous injection of the high-concentration ethylene thiourea solution and the high-concentration copper sulfate solution is kept, so that the Cu in the electrolytic cell is ensured 2+ Has a concentration of 120g/L, H 2 SO 4 Concentration of 110g/L, Cl - The concentration is 30mg/L, and the concentration of ethylene thiourea is 15 mg/L. And collecting the copper foil produced by the foil forming machine at the stage.
In this comparative example, the plating circulation system used contained a filter having adsorption capacity so that the decomposition product of ethylenethiourea during the plating process was adsorbed. The copper foil in the formal electroplating stage of the comparative example is tested by an electronic tensile testing machine, and the result shows that the tensile strength of the copper foil is 520 MPa. The density test result shows that the density of the copper foil is 99.9%.
Comparative example 2
(1) Preparing electrolyte; weighing appropriate amount of copper sulfate, sulfuric acid and hydrochloric acid to prepare electrolyte, so that Cu in the electrolyte 2+ Has a concentration of 120g/L, H 2 SO 4 Concentration of 110g/L, Cl - The concentration was 30 mg/L.
(2) Circulating electrolyte: and injecting the prepared electrolyte into an electrolytic cell, and starting an electrolyte circulation system and a heater to keep the temperature of the electrolyte at 40 ℃. The circulation system does not contain a filter having an adsorption capacity.
(3) Pre-electroplating: and connecting a power supply to ensure that the foil generator electrodeposits the copper foil in the electrolytic bath and keeps the electrolyte circulating. And calculating the circulating amount of the electrolyte from the beginning of electrifying the copper foil for deposition, and discarding the copper foil obtained by electroplating when the circulating amount of the electrolyte is less than 10 times of the total amount of the electrolyte.
(4) Formal electroplating: when the circulating amount of the electrolyte is equal to 10 times of the total amount of the electrolyte, the beginning stage of the formal electroplating is set. During the process, the continuous injection of high-concentration copper sulfate solution is maintained, so that Cu in the electrolytic cell is filled 2+ Has a concentration of 120g/L, H 2 SO 4 Concentration of 110g/L, Cl - The concentration was 30 mg/L. And collecting the copper foil produced by the foil forming machine at the stage.
In this comparative example, no additive ethylenethiourea was used in the electrolyte during both the pre-plating and the main plating. The copper foil in the formal electroplating stage of the comparative example is tested by an electronic tensile testing machine, and the result shows that the tensile strength of the copper foil is 360 MPa.
Comparative example 3
(1) Preparing electrolyte; weighing appropriate amount of copper sulfate, sulfuric acid and hydrochloric acid to prepare electrolyte, so that Cu in the electrolyte 2+ Has a concentration of 60g/L, H 2 SO 4 Concentration 60g/L, Cl - The concentration was 10 mg/L.
(2) Preparing an additive solution: weighing a proper amount of ethylene thiourea, and dissolving the ethylene thiourea in water to obtain an ethylene thiourea solution.
(3) Circulating electrolyte: mixing the prepared additive solution and electrolyte according to the ratio of 1: mixing and injecting the mixture into an electrolytic tank at a volume ratio of 1000 to ensure that the concentration of ethylene thiourea in the mixed solution is 0.5mg/L, and starting an electrolyte circulating system and a heater to keep the temperature of the electrolyte at 60 ℃. The circulation system does not contain a filter having an adsorption capacity.
(4) Pre-electroplating: and connecting a power supply to ensure that the foil generator electrodeposits the copper foil in the electrolytic bath and keeps the electrolyte circulating. And calculating the circulating amount of the electrolyte from the beginning of electrifying the copper foil for deposition, and discarding the copper foil obtained by electroplating when the circulating amount of the electrolyte is less than 10 times of the total amount of the electrolyte.
(5) Formal electroplating: when the circulating amount of the electrolyte is equal to 10 times of the total amount of the electrolyte, the beginning stage of the formal electroplating is set. During the process, only the continuous injection of high-concentration copper sulfate solution is kept, so that Cu in the electrolytic cell 2+ Has a concentration of 60g/L, H 2 SO 4 Concentration 60g/L, Cl - The concentration was 10 mg/L. And collecting the copper foil produced by the foil forming machine at the stage.
In this comparative example, the additive ethylenethiourea was not continuously added during the main plating. The tensile stress-strain curves of the copper foil obtained in different stages of the comparative example are tested by using an electronic tensile testing machine, and the result shows that when the circulating amount of the electrolyte is 10 times of the total amount of the electrolyte, the strength of the copper foil reaches 800 MPa, and then the strength of the copper foil gradually decreases to 370 MPa along with the continuous operation of the electrodeposition process and then tends to be gentle.
Claims (10)
1. A copper foil with high tensile strength is characterized in that: the copper foil has a tensile strength of 800 MPa or more; the microstructure of the copper foil in the growth direction, i.e., the thickness direction, contains 2 types of crystal grains of different sizes: one is large crystal grains with the size of 500-1000 nm and a nanometer twin structure in the inside, and the other is small crystal grains with the size of 50-100 nm; and the large crystal grains and the small crystal grains mutually surround to form a topological arrangement structure.
2. The copper foil with high tensile strength according to claim 1, wherein: the density of the copper foil is more than 99.99%.
3. The copper foil with high tensile strength according to claim 1, wherein: the crystal grains of the copper foil contain sulfur doping atoms, and the doping concentration is 5-50 ppm.
4. A method for preparing a copper foil with high tensile strength according to any one of claims 1 to 3, which is an electrolytic or electrodeposition method, characterized in that: the electrolyte contains an additive, and the additive contains ethylene thiourea decomposition products and ethylene thiourea.
5. The method of manufacturing a copper foil with high tensile strength according to claim 4, wherein: wherein the concentration of the ethylene thiourea in the electrolyte is as follows: continuously keeping 0.5-15mg/L in the electrolytic process.
6. The method of manufacturing a copper foil with high tensile strength according to claim 4, wherein: wherein the electrolyte continuously retains Cu during electrolysis 2+ The concentration of (A) is 60-120g/L, H 2 SO 4 The concentration is 60-110g/L, Cl - The concentration is 10-30 mg/L.
7. The method of manufacturing a copper foil with high tensile strength according to claim 4, wherein: the ethylene thiourea decomposition product is obtained by cyclic electroplating, and the method for obtaining the ethylene thiourea decomposition product by cyclic electroplating comprises the following steps: carrying out circulating electroplating by adopting an initial electrolyte, wherein when the circulating amount of the initial electrolyte reaches more than or equal to 10 times of the amount of the initial electrolyte, the formed ethylene thiourea decomposition product is the ethylene thiourea decomposition product; wherein the initial electrolyte contains an additive ethylene thiourea.
8. The method of manufacturing a copper foil with high tensile strength according to claim 7, wherein: wherein the initial electrolyte contains an additive ethylene thiourea with the concentration of 0.5-15 mg/L.
9. The method of manufacturing a copper foil with high tensile strength according to claim 7, wherein: what is needed isIn the initial electrolyte: cu 2+ The concentration of (A) is 60-120g/L, H 2 SO 4 The concentration is 60-110g/L, Cl - The concentration is 10-30 mg/L.
10. The method for preparing a copper foil with high tensile strength according to any one of claims 4 to 9, wherein the electrolysis is performed by using an electrolysis circulation system which does not include a filter having adsorption capacity, and the method comprises the steps of:
1) preparing an initial electrolyte: weighing appropriate amount of copper sulfate, sulfuric acid and hydrochloric acid to form a mixed solution, wherein Cu in the mixed solution 2+ The concentration of (A) is 60-120g/L, H 2 SO 4 The concentration is 60-110g/L, Cl - The concentration is 10-30 mg/L; simultaneously weighing a proper amount of ethylene thiourea and dissolving the ethylene thiourea in water to obtain an ethylene thiourea solution; mixing the ethylene thiourea solution with the mixed solution according to the proportion of 1: mixing the raw materials in an electrolytic bath according to the volume ratio of 1000 to form initial electrolyte, wherein the concentration of ethylene thiourea in the initial electrolyte is 0.5-15mg/L, and starting an electrolysis circulation system and a heater to keep the temperature of the initial electrolyte at 40-60 ℃;
2) pre-electroplating: connecting a power supply to ensure that the foil generator electrodeposits the copper foil in the electrolytic bath, and keeping the initial electrolyte circulation to perform pre-electroplating; calculating the initial electrolyte circulation amount from the beginning of electrifying to deposit the copper foil, stopping pre-electroplating when the initial electrolyte circulation amount is 10 times of the initial electrolyte amount, and abandoning the copper foil obtained by pre-electroplating;
3) electroplating of copper foil with high tensile strength: after the pre-electroplating is stopped, ethylene thiourea and copper sulfate are supplemented in the initial electrolyte to form an electrolyte II, so that the electrolyte II meets the following requirements: cu 2+ The concentration of (A) is 60-120g/L, H 2 SO 4 The concentration is 60-110g/L, Cl - The concentration is 10-30mg/L, the concentration of ethylene thiourea is 0.5-15mg/L, the electrolytic circulation system, the heater and the electroplating power supply are restarted, and electroplating is started; and in the electroplating process, the injection of ethylene thiourea and copper sulfate is continuously kept, so that the electrolyte II continuously meets the following conditions: cu 2+ The concentration of (A) is 60-120g/L, H 2 SO 4 The concentration is 60-110g/L, Cl - The concentration is 10-30mg/L, the concentration of ethylene thiourea is 0.5-15mg/L, and the temperature of the electrolyte II is kept at 40-60 ℃; and collecting the copper foil produced by the foil forming machine at the stage, namely the copper foil with high tensile strength.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020015833A1 (en) * | 2000-06-29 | 2002-02-07 | Naotomi Takahashi | Manufacturing method of electrodeposited copper foil and electrodeposited copper foil |
| CN1337475A (en) * | 2000-08-04 | 2002-02-27 | 三井金属鉱业株式会社 | Method for making electrodeposited cooper foil and electrodeposited cooper foil |
| CN112481661A (en) * | 2020-11-27 | 2021-03-12 | 九江德福科技股份有限公司 | Preparation method of fine-grain copper foil |
| CN114232037A (en) * | 2021-12-29 | 2022-03-25 | 中国科学院金属研究所 | Nano twin crystal copper foil and preparation method thereof, circuit board and current collector |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020015833A1 (en) * | 2000-06-29 | 2002-02-07 | Naotomi Takahashi | Manufacturing method of electrodeposited copper foil and electrodeposited copper foil |
| CN1337475A (en) * | 2000-08-04 | 2002-02-27 | 三井金属鉱业株式会社 | Method for making electrodeposited cooper foil and electrodeposited cooper foil |
| CN112481661A (en) * | 2020-11-27 | 2021-03-12 | 九江德福科技股份有限公司 | Preparation method of fine-grain copper foil |
| CN114232037A (en) * | 2021-12-29 | 2022-03-25 | 中国科学院金属研究所 | Nano twin crystal copper foil and preparation method thereof, circuit board and current collector |
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