CN116944241A - Preparation method of composite foil with high deformation resistance - Google Patents

Preparation method of composite foil with high deformation resistance Download PDF

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Publication number
CN116944241A
CN116944241A CN202310653050.9A CN202310653050A CN116944241A CN 116944241 A CN116944241 A CN 116944241A CN 202310653050 A CN202310653050 A CN 202310653050A CN 116944241 A CN116944241 A CN 116944241A
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rolling
foil
composite
aluminum
coil stock
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袁鹏飞
康美玲
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Fujian Super Power New Energy Co ltd
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Fujian Super Power New Energy Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/40—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling foils which present special problems, e.g. because of thinness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/38—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling sheets of limited length, e.g. folded sheets, superimposed sheets, pack rolling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/16—Control of thickness, width, diameter or other transverse dimensions
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/043—Processes of manufacture in general involving compressing or compaction
    • H01M4/0435—Rolling or calendering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B2261/00—Product parameters
    • B21B2261/02—Transverse dimensions
    • B21B2261/04—Thickness, gauge
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • General Chemical & Material Sciences (AREA)
  • Electrochemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Metal Rolling (AREA)
  • Cell Electrode Carriers And Collectors (AREA)

Abstract

The invention discloses a preparation method of a composite foil, which comprises the following steps: (1) material selection and preparation before rolling: selecting copper foil coil stock and two aluminum foil coil stock with the same width, and sequentially laminating the copper foil coil stock and the two aluminum foil coil stock according to the sequence of aluminum foil, copper foil and aluminum foil; (2) rough rolling: rolling for 3-5 times by using a rolling mill, wherein the pressing rate of each rolling is 40% -65%, and forming a composite foil; (3) finish rolling: rolling the composite foil for 3-6 times by using a finishing roll, wherein the rolling reduction rate of each rolling is 20% -40% until the thickness of the composite foil reaches the thickness of a target product; (4) annealing: and (5) carrying out annealing treatment on the finish-rolled composite foil to finish the preparation. After the composite foil is manufactured into the lithium battery anode, the heating of the lithium battery anode can be reduced, and the internal resistance is further reduced.

Description

Preparation method of composite foil with high deformation resistance
The present application is a divisional application taking an invention patent with the application date of 2021, 08, 5, the application number of 2021108943013 and the name of a preparation method of a composite foil as a parent application.
Technical Field
The invention relates to the field of batteries, in particular to a preparation method of a composite foil.
Background
As a secondary battery having the characteristics of high energy density, light weight, long cycle life, environmental protection, and the like, a lithium battery is widely used in various fields such as automobiles, numerals, energy storage, and the like. However, as technology advances, higher demands are placed on the performance of lithium batteries. Such as a lithium battery to reduce heat generation, increase service life, etc.
Among common materials, aluminum foil is adopted as a common positive electrode foil of a lithium battery because the aluminum foil has relatively good conductivity, good flexibility and low production cost, and a compact oxide film can be generated on the surface of the aluminum foil to ensure that the aluminum foil has good stability.
However, pure aluminum foil is used as a positive current collector, and meanwhile, the defects of relatively large internal resistance and poor heat dissipation performance exist, so that the heat dissipation performance of the produced lithium battery is poor.
Disclosure of Invention
The technical problems to be solved by the invention are as follows: the preparation method of the composite foil material reduces the internal resistance of the lithium battery.
In order to solve the technical problems, the invention adopts the following technical scheme:
the preparation method of the composite foil comprises the following steps:
(1) Material selection and preparation before rolling: selecting copper foil coil stock and two aluminum foil coil stock with the same width, and sequentially laminating the copper foil coil stock and the two aluminum foil coil stock according to the sequence of aluminum foil, copper foil and aluminum foil;
(2) Rough rolling: rolling for 3-5 times by using a rolling mill, wherein the pressing rate of each rolling is 40% -65%, and forming a composite foil;
(3) Finish rolling: rolling the composite foil for 3-6 times by using a finishing roll, wherein the rolling reduction rate of each rolling is 20% -40% until the thickness of the composite foil reaches the thickness of a target product;
(4) Annealing: and (5) carrying out annealing treatment on the finish-rolled composite foil to finish the preparation.
The invention has the beneficial effects that: in the invention, the composite foil material comprising two layers of aluminum foils and one layer of copper foil is formed by sequentially laminating aluminum foils, copper foils and aluminum foils and sequentially performing rough rolling, finish rolling and annealing. The composite foil with good heat dissipation and high oxidation resistance is prepared by utilizing the good heat dissipation performance of copper and the good oxidation resistance of aluminum foil. The annealing aims to eliminate work hardening and cold rolling stress, recover the plasticity and toughness of the copper foil and the aluminum foil, form interface reaction between grain structures and improve the bonding strength of the composite foil. When the composite foil is manufactured into the positive electrode of the lithium battery, the heat dissipation performance of the positive electrode is improved, the resistance value of the current collector is reduced, the direct current internal resistance of the battery core can be effectively reduced, and the effect of reducing the internal resistance of the lithium battery is achieved.
Drawings
FIG. 1 is a schematic illustration of a process for preparing a composite foil according to the present invention;
fig. 2 is a direct current internal resistance box diagram of the composite foil and the common aluminum foil manufactured in the first embodiment of the invention when the composite foil and the common aluminum foil are respectively used as the positive electrode of the battery cell;
fig. 3 is a graph showing a 0.5C charging temperature rise curve when the composite foil and the common aluminum foil manufactured in the first embodiment of the present invention are used as the positive electrode of the battery cell, respectively.
Description of the reference numerals:
1. aluminum foil; 2. copper foil.
Detailed Description
In order to describe the technical contents, the achieved objects and effects of the present invention in detail, the following description will be made with reference to the embodiments in conjunction with the accompanying drawings.
The preparation method of the composite foil comprises the following steps:
(1) Material selection and preparation before rolling: selecting copper foil coil stock and two aluminum foil coil stock with the same width, and sequentially laminating the copper foil coil stock and the two aluminum foil coil stock according to the sequence of aluminum foil, copper foil and aluminum foil;
(2) Rough rolling: rolling for 3-5 times by using a rolling mill, wherein the pressing rate of each rolling is 40% -65%, and forming a composite foil;
(3) Finish rolling: rolling the composite foil for 3-6 times by using a finishing roll, wherein the rolling reduction rate of each rolling is 20% -40% until the thickness of the composite foil reaches the thickness of a target product;
(4) Annealing: and (5) carrying out annealing treatment on the finish-rolled composite foil to finish the preparation.
The working principle of the invention is as follows:
the copper foil is clamped between two layers of aluminum foils, and the good heat dissipation performance of the copper foil and the high oxidation resistance of the aluminum foil are utilized, so that the heat dissipation performance of the formed composite foil is improved, the performance is stable, and when the composite foil is manufactured into the anode of a lithium battery, the heat dissipation performance of the anode of the lithium battery can be reduced, and then the internal resistance is reduced.
From the above description, the beneficial effects of the invention are as follows: in the invention, the composite foil material comprising two layers of aluminum foils and one layer of copper foil is formed by sequentially laminating aluminum foils, copper foils and aluminum foils and sequentially performing rough rolling, finish rolling and annealing. The composite foil with good heat dissipation and high oxidation resistance is prepared by utilizing the good heat dissipation performance of copper and the good oxidation resistance of aluminum foil. The annealing aims to eliminate work hardening and cold rolling stress, recover the plasticity and toughness of the copper foil and the aluminum foil, form interface reaction between grain structures and improve the bonding strength of the composite foil. When the composite foil is manufactured into the positive electrode of the lithium battery, the heat dissipation performance of the positive electrode is improved, the resistance value of the current collector is reduced, the direct current internal resistance of the battery core can be effectively reduced, and the effect of reducing the internal resistance of the lithium battery is achieved.
Further, the copper foil coil stock in the step (1) is industrial pure copper T2.
Further, the aluminum foil coil stock in the step (1) is obtained by alloying and heat treatment of pure aluminum.
Further, the alloying and heat treatment are specifically to add Si, mn and Co into pure aluminum in proportion for preliminary alloying, and to carry out annealing treatment for 6-24 h under the condition of 300-500 ℃.
As is apparent from the above description, when the hardness of two metal materials differs greatly, excessive energy is consumed on one side of the softer metal material during rolling, so that plastic deformation of both sides of the composite material is asynchronous, and in order to achieve a good composite state of the copper foil and the aluminum foil, pure aluminum is alloyed and heat treated to improve the hardness of the aluminum foil, so that the hardness of the aluminum foil is close to that of the copper foil, and further, during rolling, the aluminum foil and the copper foil can be deformed in a coordinated manner to achieve a good composite state.
Further, the mass ratio of Si is 0.5-7.50%, the mass ratio of Mn is 0.5-2.0%, and the mass ratio of Co is 0.1-1.5%.
From the above description, it is known that Si, mn, co, etc. are added to pure aluminum for alloying with pure aluminum so that the hardness of aluminum foil approaches that of copper foil.
Further, the thickness of the aluminum rolled coil stock in the step (1) is 0.5-8 mm, and the ratio of the thickness of the copper foil to the thickness of the aluminum foil is 1/3-1/5.
As can be seen from the above description, since the deformation resistance of the aluminum foil is lower than that of the copper foil, the pressing rate of the aluminum foil during rolling is larger than that of the copper foil, and in order to ensure that the deformation rate of the aluminum foil is consistent with that of the copper foil during rolling, the thickness ratio between the aluminum foil and the copper foil is adjusted, and meanwhile, the use amount of the copper foil is reduced, so that the production cost is reduced.
Further, the rolling reduction rate of the first rolling in the step (2) is not less than 60%.
As is apparent from the above description, since the deformation resistance and elongation of two metals of copper and aluminum are different, and the presence of an oxide film on the surface of an aluminum foil makes it difficult to compound the two metals, a large reduction rate is required to compound the two metals, and thus the first reduction rate is not less than 60%, and at a large reduction rate, the deformation resistances of the two tend to coincide, so that the deformation of the rolled aluminum foil and the copper foil can be synchronized.
Further, wen Za is adopted for the last rolling in the step (2), and the Wen Za is specifically implemented by heating the rolling roller of the rolling mill to 90-250 ℃ for rolling.
From the above description, the heated rolling roller can improve the activity of metal atoms in the rolling process, is beneficial to copper-aluminum bimetal compounding, and can still realize good combination of copper-aluminum metals under the condition of low pressing rate.
Further, the annealing treatment temperature in the step (4) is 200-400 ℃, and the annealing time is 1-5 h.
Example 1
The preparation method of the composite foil comprises the following steps:
(1) Material selection and preparation before rolling: selecting copper foil coil stock and two aluminum foil coil stock with the same width, and sequentially laminating the copper foil coil stock and the two aluminum foil coil stock according to the sequence of aluminum foil 1-copper foil 2-aluminum foil 1; wherein, the copper foil coil stock is industrial pure copper (Cu is more than or equal to 99.95 percent) T2, and the thickness is 2mm; the aluminum foil coil stock was made of pure aluminum, which was primarily alloyed with elements added with Si, mn and Co in a mass ratio of 1.5%, 2.0% and 0.5% and annealed at a temperature of 300 c for 24 hours, and had a thickness of 8mm.
(2) Rough rolling: rolling four times by using a rolling mill, wherein the rolling reduction of the first rolling is 60%, the rolling reduction of the second to fourth rolling is kept at 40% -45%, and the rolling rolls of the rolling mill are heated to 180 ℃ for rolling to form a composite foil in the specific operation of Wen Za, wen Za for the fourth rolling;
(3) Finish rolling: carrying out five times of rolling on the composite foil by using a finishing roll, wherein the rolling reduction rate of each rolling is 30 percent until the thickness of the composite foil reaches 15 mu m of the thickness of a target product;
(4) Annealing: and (3) annealing the finish-rolled composite foil for 3 hours at the temperature of 300 ℃, so as to eliminate processing stress, enable the aluminum foil and the copper foil to form inter-grain structure interface reaction, improve the bonding strength of the composite strip and finish the preparation.
Preparation of a lithium battery half cell: (1) to verify the performance of the composite foil, the following LiFePO4: super P: CNTS: pvdf=95: 2:0.5:2.5 weighing the materials, mixing the materials with NMP as a solvent, mixing the materials into uniform and stable slurry, uniformly coating the slurry on the 15 mu m composite foil prepared in the step (4) and a common 15 mu m aluminum foil respectively by using a transfer coater, rolling the composite foil and the common 15 mu m aluminum foil, and preparing two pieces of 150 mm/200 mm pole pieces respectively.
(2) According to the graphite: super P: CMC: the above materials were weighed in the ratio sbr=92:2:2.5:3.5, water was used as a solvent, the above materials were mixed to a uniform and stable slurry, the slurry was uniformly coated on a copper foil with a transfer coater, and a pole piece of 152mm x 202mm was produced after rolling.
(3) The metal lithium sheet is used as a negative electrode, a 10-mu m diaphragm is used, liPF6 is used as lithium salt and PC/EC/DMC/EMC is used as electrolyte of a solvent, the 15-mu m composite foil and a common 15-mu m aluminum foil are used as positive electrode sheets to be respectively assembled into two 20Ah soft package batteries, and electric performance tests are carried out.
According to fig. 2 and 3, it can be obtained that the composite foil as the positive current collector can not only effectively reduce the internal resistance of the battery cell, but also effectively improve the cycle discharge performance of the battery cell, and improve the temperature rise during operation and the safety performance of the battery.
It is noted that the aluminum/copper/aluminum composite foils in fig. 2 and 3 refer to the composite foils in this embodiment.
Example two
The preparation method of the composite foil comprises the following steps:
(1) Material selection and preparation before rolling: selecting copper foil coil stock and two aluminum foil coil stock with the same width, and sequentially laminating the copper foil coil stock and the two aluminum foil coil stock according to the sequence of aluminum foil 1-copper foil 2-aluminum foil 1; wherein, the copper foil coil stock is industrial pure copper (Cu is more than or equal to 99.95 percent) T2, and the thickness is 1.5mm; the aluminum foil coil stock was made of pure aluminum, which was primarily alloyed with elements added with 3.0% by mass of Si, 1.0% by mass of Mn and 0.5% by mass of Co and annealed at 300 ℃ for 24 hours, and had a thickness of 6mm.
(2) Rough rolling: rolling four times by using a rolling mill, wherein the rolling reduction of the first rolling is 60%, the rolling reduction of the second to fourth rolling is kept at 40% -45%, and the rolling rolls of the rolling mill are heated to 210 ℃ for rolling to form a composite foil in the specific operation of Wen Za, wen Za for the fourth rolling;
(3) Finish rolling: rolling the composite foil by using a finishing roll for four times, wherein the rolling reduction rate of each rolling is 35% until the thickness of the composite foil reaches 14 mu m of the thickness of a target product;
(4) Annealing: and (3) annealing the finish-rolled composite foil for 2 hours at the temperature of 250 ℃, eliminating processing stress, enabling an inter-grain structure interface reaction to be formed between the aluminum foil and the copper foil, improving the bonding strength of the composite strip, and finishing the preparation.
Example III
The preparation method of the composite foil comprises the following steps:
(1) Material selection and preparation before rolling: selecting copper foil coil stock and two aluminum foil coil stock with the same width, and sequentially laminating the copper foil coil stock and the two aluminum foil coil stock according to the sequence of aluminum foil 1-copper foil 2-aluminum foil 1; wherein, the copper foil coil stock is industrial pure copper (Cu is more than or equal to 99.95 percent) T2, and the thickness is 3.5mm; the aluminum foil coil stock was made of pure aluminum, which was primarily alloyed with elements added with Si, mn and Co in a mass ratio of 1.0%, 0.5% and 1.2% and annealed at a temperature of 420 ℃ for 8 hours, and had a thickness of 12mm.
(2) Rough rolling: five times of rolling are carried out by a rolling mill, the rolling reduction of the first time is 50%, the rolling reduction of the second time to the fourth time is kept between 30 and 40%, and the rolling rolls of the rolling mill are heated to 160 ℃ for rolling to form a composite foil in the specific operation of Wen Za and Wen Za for the third time;
(3) Finish rolling: carrying out six times of rolling on the composite foil by using a finishing roll, wherein the rolling reduction rate of each rolling is 20 percent until the thickness of the composite foil reaches 11 mu m of the thickness of a target product;
(4) Annealing: and (3) annealing the finish-rolled composite foil for 2 hours at the temperature of 330 ℃, eliminating processing stress, enabling an inter-grain structure interface reaction to be formed between the aluminum foil and the copper foil, improving the bonding strength of the composite strip, and finishing the preparation.
Comparative example
The preparation method of the common foil comprises the following steps:
(1) Material selection and preparation before rolling: the aluminum foil coil stock is selected to be made of pure aluminum with the thickness of 10mm, wherein the pure aluminum is prepared by adding elements of Si, mn and Co in the mass ratio of 1.5%, 2.0% and 0.5% for preliminary alloying and annealing treatment for 24 hours at the temperature of 300 ℃.
(2) Rough rolling: rolling four times by using a rolling mill, wherein the rolling reduction of the first rolling is 60%, the rolling reduction of the second to fourth rolling is kept at 40% -45%, and the rolling rolls of the rolling mill are heated to 180 ℃ for rolling to form a rough rolled foil in the fourth rolling by adopting the concrete operation of Wen Za and Wen Za;
(3) Finish rolling: carrying out five times of rolling on the aluminum foil by using a finishing roll, wherein the rolling reduction rate of each rolling is 30 percent until the thickness of the foil reaches 15 mu m of the thickness of a target product;
(4) Annealing: and (3) annealing the finish-rolled aluminum foil for 3 hours at the temperature of 300 ℃ to eliminate the processing stress and finish the preparation of the aluminum foil.
In summary, according to the preparation method of the composite foil provided by the invention, the copper foil has good heat dissipation performance, but when the copper foil is simply used as the positive electrode current collector of the lithium battery, the copper foil oxide layer is loose, so that a large amount of copper is oxidized to generate copper oxide under the high-potential condition, and Li of the negative electrode and the copper oxide react in a lithium intercalation mode under the higher potential condition. Therefore, after the copper foil and the two layers of aluminum foils with similar hardness are roughly rolled to form the composite foil with good composite state, the thickness of the composite foil reaches the thickness of a target product through finish rolling, and the annealing is carried out to form grain structure interface reaction between the copper foil and the two layers of aluminum foils, so that the bonding strength of the copper foil and the aluminum foils is improved, the manufactured composite foil is stable in structure, has good heat dissipation performance and good oxidation resistance, and after the composite foil is manufactured into the positive electrode of the lithium battery, the heat dissipation performance of the positive electrode of the lithium battery can be improved, and the internal resistance of the positive electrode of the lithium battery is reduced.
The foregoing description is only illustrative of the present invention and is not intended to limit the scope of the invention, and all equivalent changes made by the specification and drawings of the present invention, or direct or indirect application in the relevant art, are included in the scope of the present invention.

Claims (5)

1. The preparation method of the composite foil with high deformation resistance is characterized by comprising the following steps of:
(1) Material selection and preparation before rolling: selecting copper foil coil stock and two aluminum foil coil stock with the same width, and sequentially laminating the copper foil coil stock and the two aluminum foil coil stock according to the sequence of aluminum foil, copper foil and aluminum foil;
the aluminum foil coil stock is obtained by alloying and heat treatment of pure aluminum;
the alloying and heat treatment are specifically that Si, mn and Co are added into pure aluminum according to a proportion for preliminary alloying, and annealing treatment is carried out for 6-24 hours under the condition that the temperature is 300-500 ℃;
(2) Rough rolling: rolling for 3-5 times by using a rolling mill, wherein the rolling reduction rate of each rolling is 40% -65%, and the rolling reduction rate of one rolling is not less than 60%, so that a composite foil is formed; the last rolling in the step (2) adopts warm rolling, and the temperature of the warm rolling is 90-250 ℃;
(3) Finish rolling: rolling the composite foil for 3-6 times, wherein the rolling reduction rate of each rolling is 20% -40% until the thickness of the composite foil reaches the thickness of a target product;
(4) Annealing: and (3) carrying out annealing treatment on the finish-rolled composite foil, wherein the annealing treatment temperature is 200-400 ℃, and the annealing time is 1-5 h, so as to finish the preparation.
2. The method of producing a composite foil having high deformation resistance according to claim 1, wherein the copper foil coil in the step (1) is an industrial pure copper T2.
3. The method for preparing a composite foil with high deformation resistance according to claim 1, wherein the alloying and heat treatment are specifically to add Si, mn and Co in proportion to pure aluminum for preliminary alloying, and to perform annealing treatment at 300-500 ℃ for 6-24 h.
4. A method of producing a composite foil having a high deformation resistance according to claim 3, wherein the mass ratio of Si is 0.5 to 7.50%, the mass ratio of Mn is 0.5 to 2.0%, and the mass ratio of Co is 0.1 to 1.5%.
5. The method of producing a composite foil having high deformation resistance according to claim 1, wherein the thickness of the aluminum foil coil stock in the step (1) is 0.5mm to 8mm, and the ratio of the thickness of the copper foil to the thickness of the aluminum foil is 1/3 to 1/5.
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