CN114855101B

CN114855101B - Manufacturing method of positive aluminum foil material for pure aluminum-based battery tab

Info

Publication number: CN114855101B
Application number: CN202210534792.5A
Authority: CN
Inventors: 蒲剑丛; 贺耀文; 左宏; 沈国柱; 李心愿; 崔敬鑫; 刘延军
Original assignee: Xinjiang Joinworld Co Ltd
Current assignee: Xinjiang Joinworld Co Ltd
Priority date: 2022-05-17
Filing date: 2022-05-17
Publication date: 2023-04-28
Anticipated expiration: 2042-05-17
Also published as: CN114855101A

Abstract

The invention discloses a manufacturing method of an anode aluminum foil material for a pure aluminum-based battery tab, and belongs to the technical field of industrial high-purity aluminum. The method comprises the following steps: (1) hot rolling: carrying out soaking treatment on the pure aluminum cast ingot, and carrying out hot rolling to obtain a hot rolled coiled material with the thickness of 5-7 mm; (2) 2.0-3.5mm hard cold-rolled coil is obtained through 2-3 times of cold rolling; (3) intermediate annealing: the intermediate annealing temperature is controlled to be 400-450 ℃, and the heat preservation time is 6-12 h; (4) Cold rolling for 4-8 times to 0.1-0.4 mm thickness to obtain a hard foil coil finished product; (5) And annealing the finished product to obtain a soft foil coil finished product with the thickness of 0.1-0.4 mm and the tensile strength of more than or equal to 80 MPa. The method provided by the invention is used for preparing the tab anode aluminum strip material with excellent performance, namely 0.1mm-0.4mm high conductivity, high bending and high surface.

Description

Manufacturing method of positive aluminum foil material for pure aluminum-based battery tab

Technical Field

The invention relates to the technical field of aluminum-based batteries, in particular to a manufacturing method of an anode aluminum foil material for a pure aluminum-based battery tab.

Background

The electrode lug is a raw material of a lithium ion polymer battery product and is used as a material for conducting connection of a power battery and a 3C battery. For example, a mobile phone battery, a bluetooth battery, a notebook battery and the like used in life all need to use a tab. The battery is divided into positive and negative poles, and the electrode lugs are metal conductors for leading the positive and negative poles out of the battery core, so that the ears of the positive and negative poles of the battery are contact points during charge and discharge. This contact is not the copper sheet that we see on the exterior of the cell, but rather a connection inside the cell. The tab is divided into three materials, the positive electrode of the battery is made of aluminum (Al) material, the negative electrode of the battery is made of nickel (Ni) material, the negative electrode of the battery is also made of copper nickel plating (Ni-Cu) material, and the tab and the negative electrode are formed by compounding a film and a metal belt. The special use condition of the tab material makes the tab material provide strict use requirements for the characteristics of tensile strength, conductivity, welding strength, bending and the like of the material. The main research direction is based on the development of the aspects of reducing the resistivity, controlling the material strength on a certain basis and simultaneously having higher bending characteristics.

The 1 xxx-series aluminum alloy has excellent conductivity and high plasticity, and is widely used for conductor materials with low strength, and in order to obtain good plasticity, the materials are required to have fine and uniform grain structure characteristics. The products are generally based on pure aluminum, and in order to ensure the improvement of strength and bending at the same time, the synchronous improvement of strength, bending and plasticity is realized by alloying on the basis of pure aluminum and then processing and heat treatment and other technological methods.

The existing aluminum strip materials for producing new energy power batteries and 3C digital battery lugs are divided into two main production process flows: cast rolling and hot rolling. The cast rolling method, as disclosed in patent CN201811509825.0, is a preparation method of an aluminum strip material for a tab of a new energy power battery, namely, a cast rolling coil with the thickness of about 7mm is directly produced by the cast rolling method, and an aluminum foil blank is obtained after cold rolling and annealing; the other is a preparation method of a 1-series aluminum alloy foil for the lug anode of the soft-package lithium battery, which is a hot rolling method, such as disclosed in patent CN202110684014.X, and is characterized in that the soft-package lithium battery is cast into ingots in a semi-continuous mode, hot rolled and cogged after face milling, and then cooled into blanks. The aluminum foil blanks produced by the two production processes are used at present, and have advantages and disadvantages. The hot rolling method has uniform structure and few defects, and is beneficial to rolling; the blank produced by casting and rolling method has short production flow and is more suitable for rolling thinner plates or foils.

The casting and rolling method for producing the blank is divided into two production processes, namely casting and rolling by remelting aluminum ingots, casting and rolling by directly adopting electrolytic molten aluminum liquid, and compared with casting and rolling by remelting aluminum ingots for producing the aluminum foil blank, the casting and rolling by adopting electrolytic molten aluminum liquid for producing the aluminum foil blank has some technical problems to be solved. Because the temperature of the electrolytic aluminum liquid is generally about 930 ℃, the temperature can be kept between 860 and 900 ℃ even if the electrolytic aluminum liquid is transported to a casting shop, the water content of raw and auxiliary materials used in the electrolysis of aluminum is high, the temperature of the electrolytic aluminum liquid is high, the gas content in the aluminum liquid is especially high in hydrogen content, therefore, the degassing procedure before casting and rolling is particularly important, once the degassing is unfavorable, the gas content of cast and rolled blanks exceeds the standard requirement or the pinhole degree of the subsequently processed plate is increased, the reject ratio of products is increased, and even the materials cannot be processed to the designed size.

Although the existing casting and rolling method for producing aluminum foil is perfect and can reduce production cost, due to the process characteristics of the casting and rolling process, the inherent process conditions cause more defects of inclusion and the like in a casting and rolling plate, the surface of the product is very easy to generate defects of pinholes, peeling and the like, and the product is unqualified due to the problem of component segregation, and the aluminum foil is not suitable for middle-high-end aluminum tab materials with higher product quality requirements.

The tensile strength of the aluminum foil product produced by the hot rolling method in the prior art is lower by only 70-80MPa, and the quality control of subsequent slitting processing can be affected. In addition, the electrolyte resistance and the electric conductivity of the tab material are not explicitly controlled and specified. Along with the rapid development of new energy battery industry, higher and more severe requirements are also put forward on the quality of tab materials, and the aluminum foil materials for the tabs are promoted to continuously progress towards the requirements of high strength, high bending, high conductivity and high surface.

Disclosure of Invention

The invention aims to provide a manufacturing method of an anode aluminum foil material for a pure aluminum-based battery tab, which adopts raw materials based on 99.90%, strictly controls the intake of main elements, and improves the mechanical property, the electric conductivity and the tissue uniformity of a product through the process control of soaking, hot rolling, cold rolling, foil rolling and annealing.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

a manufacturing approach of the positive aluminum foil material for the tab of the pure aluminum-based battery, the method adopts the semi-continuous casting to produce the platy ingot, hot-roll it first, the subsequent cold working, heat treatment, finishing production obtain the positive aluminum foil material for the tab of the pure aluminum-based battery; the method comprises the following steps:

(1) And (3) hot rolling: carrying out hot rolling on pure aluminum cast ingots after soaking treatment, wherein the initial hot rolling temperature is 520-560 ℃, the final rolling temperature is 270-300 ℃, the hot rolling passes are 17-21, the rolling reduction rate of coiling passes is 40-60%, and the hot rolled coiled materials with the thickness of 5-7mm are obtained after rolling;

(2) The cogged hot rolled coil is subjected to 2-3 times of cold rolling to obtain a 2.0-3.5mm hard cold rolled coil;

(3) Intermediate annealing: the intermediate annealing temperature is controlled at 400-450 ℃ and the heat preservation time is 6-12 h.

(4) And (3) carrying out cold rolling for 4-8 times to the thickness of a finished product of 0.1-0.4 mm after intermediate annealing to obtain a hard foil coil finished product with the foil surface roughness Ra value of 0.15-0.30 mu m.

(5) And annealing the hard foil coil finished product to obtain a soft foil coil finished product with the thickness of 0.1-0.4 mm and the tensile strength of more than or equal to 80 MPa.

In the step (1), the preparation process of the pure aluminum cast ingot comprises the following steps: smelting an aluminum ingot with the purity of more than or equal to 99.90wt.% as a raw material, adding 0.43-0.45wt.% Fe and 0.13-0.16wt.% Si in an aluminum melt, and casting the melt to obtain the pure aluminum ingot, wherein the Al content of the pure aluminum ingot is more than or equal to 99.30wt.%.

In the step (1), the soaking treatment process is as follows: soaking the ingot at 550-610 ℃ and preserving heat for 10-20 h; the main purpose of soaking is to eliminate defects in the casting process and component segregation, so that the structure and components are sufficiently homogenized, and the hot rolling is facilitated.

In the hot rolling process of the step (1), the rolling speed is controlled to be 60-120 m/min.

The cold rolling reduction ratio between the intermediate annealing (first annealing) and the finished annealing (second annealing) is more than 80 percent.

And (3) carrying out the annealing process of the finished product in the step (5) after cleaning, drying, shearing (slitting) the finished product of the soft foil coil obtained after the cold rolling in the step (4).

When the soft foil coil finished product is cleaned, a cleaning agent (oil) with a flash point of 30-70 ℃ and a dry point of less than or equal to 220 ℃ is selected so as to achieve the aim of quick volatilization, the cleaning speed is controlled to be 60-100m/min, the foil surface is ensured to be dried, and the residue of the cleaning agent (oil) is reduced; controlling the temperature of a drying box to be 90-130 ℃ during drying; transferring the cleaned and dried finished foil roll to a shearing procedure, and cutting according to the specified product width specification, wherein the edge burr is less than 0.1mm; and (5) carrying out the annealing process of the finished product in the step (5) on the foil coil after the cutting.

In the step (5), the annealing temperature of the finished product is 300-400 ℃, and the heat preservation time is 4-10h.

In the annealing of the finished product in the step (5), vacuum annealing is performed under the protection gas of nitrogen or argon.

The design principle and the beneficial effects of the invention are as follows:

the invention mainly uses a hot rolling method to produce a battery tab product with the Al content of more than 99.30 percent (the specific chemical composition is (wt.%).

In general, the types of aluminum tab materials are classified according to the thickness of the aluminum foil, and < 0.2mm belongs to the category of 3C digital tabs (main specifications of 0.100mm, 0.125mm, 0.150 mm), and > 0.2mm belongs to the category of power tabs (main specifications of 0.3mm, 0.4 mm). The invention is compatible with the use requirements of two products at the same time, and the 0.1mm-0.4mm high-conductivity, high-bending and high-surface tab anode aluminum strip material with excellent performance is obtained.

Compared with the prior art that aluminum foil blanks are produced by a hot rolling method, the method uses the single-frame hot rolling mill to roll the plate ingot into the hot rolled coil with the thickness of 5-7mm, then mainly controls the cold rolling processing rate between the intermediate annealing (the first annealing) and the finished annealing (the second annealing) to be more than 80%, strictly controls the finished annealing temperature and the heat preservation time, and finally obtains fine and uniform grain structures, the average grain size is less than 40 mu m, the grain size series index is more than 6, the tensile strength of the material is improved to 80-90MPa while the plasticity index is ensured, the high-strength and high-plasticity product performance can be realized, the slitting difficulty (the narrowest slitting to 1mm width) of the aluminum foil during downstream customer production can be reduced to a certain extent, and the quality problems of sticking and poor plate shape are avoided.

Drawings

Fig. 1 is a schematic diagram of the surface grain size and distribution of the tab aluminum tape product of example 1.

Detailed Description

For a further understanding of the present invention, the present invention is described below with reference to the examples, which are only illustrative of the features and advantages of the present invention and are not intended to limit the scope of the claims of the present invention.

The invention provides a manufacturing method of a positive aluminum foil material for a pure aluminum-based battery tab, which adopts semi-continuous casting to produce a plate ingot, and is suitable for soft finished products with the specification thickness of 0.1mm-0.4mm through a hot rolling method and subsequent cold processing, heat treatment and finishing. The specific production process is as follows:

1. the ingot is soaked at 550-610 ℃ for 10-20 hours, and the main purpose of soaking is to eliminate defects in the casting process and component segregation, so that the structure and the components are fully homogenized, and the hot rolling is facilitated.

2. The hot rolling is started within the temperature range of 520-560 ℃, the final rolling temperature is controlled to 270-300 ℃, the hot rolling pass is 17-21, the rolling reduction rate of the coiling pass is controlled to be 40% -60%, the purpose is to crush grains and refine middle tissues, the rolling speed is ensured to be within a certain range (60 m/min-120 m/min), the temperature of a strip is controlled by matching with emulsion lubrication, the precipitation of compounds is reduced, the hot rolled coiled material with the thickness of 5-7mm is obtained by rolling, and the design of the rolling reduction rate is ensured to avoid surface aluminum sticking.

3. The hot rolled coil is subjected to 2-3 times of cold rolling to obtain a 2.0-3.5mm hard cold rolled coil, trimming is finished, the quality of the edge is ensured, the defect of strip breakage in subsequent rolling is prevented by cleaning, surface drying is ensured, and the intermediate annealing is performed after the residue of cleaning agent (oil) is reduced.

4. The intermediate annealing temperature is controlled at 400-450 ℃, the heat preservation time is 6-12h, the work hardening is eliminated, the stress concentration phenomenon is eliminated, and the product performance is ensured.

5. And (3) after annealing, carrying out cold rolling for 4-8 times to obtain a finished product with the thickness of 0.1-0.4 mm, and obtaining a hard finished product with the foil surface roughness Ra value of 0.15-0.30 mu m.

The cold rolling reduction ratio between the intermediate annealing (first annealing) and the finished product annealing (second annealing) is more than 80%, the dislocation density in the metal is increased, the cold deformation strengthening effect is fully exerted, the hard state strength of the finished product of the material before annealing is improved, the annealing temperature and the heat preservation time of the finished product are strictly controlled, and finally the O-state finished product with the tensile strength of more than or equal to 80Mpa is obtained.

6. The finished foil coil is cleaned, the flash point of the cleaning agent (oil) is selected to be 30-70 ℃ and the dry point is less than or equal to 220 ℃, so as to achieve the purpose of quick volatilization, the cleaning speed is controlled to be 60-100m/min, the foil surface is ensured to be dried, the residue of the cleaning agent (oil) is reduced, and the drying box is controlled to be 90-130 ℃.

7. The cleaned finished foil coil is transferred to a shearing procedure, and is cut according to the width specification of the product appointed by a customer, and the burr at the edge is less than 0.1mm.

8. And (3) carrying out finished product annealing on the foil coil after cutting, and carrying out vacuum annealing by using protective gas (nitrogen or argon), wherein the finished product annealing temperature is 300-400 ℃, and the heat preservation time is 4-10 hours.

9. After finished product annealing is finished, rewinding and checking the surface quality, and packaging after the mechanical property is checked to be qualified. The final annealing atmosphere is selected from protective gas nitrogen or argon so as to prevent foil surface oxidation during annealing, reduce the adhesion of oxidation of residual oil products on the foil surface, quickly volatilize and form a uniform oxide film.

Example 1:

the process for preparing the positive aluminum foil material for the pure aluminum-based battery tab in the embodiment is as follows:

1. soaking the plate ingot: the ingot is subjected to soaking heat preservation for 8 hours at 605 ℃ according to the composition control of the table 1, and then cooled to 550 ℃ for heat preservation for 4 hours.

Table 1 ingot composition (wt.%)

Fe	Si	Cu	Mn	Zn	Mg	Ga	Ti	Al％
									0.4415	0.1469	0.0006	0.0006	0.0017	0.0008	0.0087	0.0218	≥99.30

2. And (3) hot rolling: the initial rolling temperature of the cast ingot is 540 ℃, the thickness of the cast ingot is 7.0mm after 19 passes, the rolling pass reduction rate is 40% -60%, the rolling speed is 60m/min-100m/min, and the hot rolled coil with the final rolling temperature of 285 ℃ is obtained.

3. Primary cold rolling: the hot rolled coil is subjected to 2-pass cold rolling to obtain a 3.0mm hard cold rolled strip, the roller roughness is 0.45 mu m, the rolling speed is 300m/min, the strip is cleaned by 60# cleaning oil before intermediate annealing, and the outer ring of the coil is tightly tightened.

4. Intermediate annealing: heating to 400 ℃ by adopting a nitrogen annealing furnace according to 6 hours, preserving heat for 8 hours, discharging and cooling.

5. Secondary cold rolling: and (3) continuously rolling the aluminum coil subjected to intermediate annealing for 5 times to obtain a finished coil with the thickness of 0.4mm, wherein the roller roughness is 0.25 mu m, and the rolling speed is 500m/min.

6. Cleaning: and 60# cleaning oil is selected to be matched with a soft brush roller to clean the plate and strip, the cleaning speed is 100m/min, the temperature of a drying box is controlled at 100 ℃, and the surface cleaning and drying of the cleaned aluminum coil are ensured.

7. And (3) annealing a finished product: heating to 400 ℃ by adopting a nitrogen annealing furnace according to 6 hours, preserving heat for 8 hours, discharging and cooling.

8. And rewinding for surface quality inspection to obtain a finished product of the positive aluminum strip for the battery tab. The product has fine and uniform grain structure, average grain size below 40 μm, and grain size series index > 6 (figure 1), and can ensure plasticity index and increase tensile strength of material to 80-90MPa. The specific properties of the product are shown in Table 2 below.

TABLE 2 Properties of the Positive electrode aluminum strip finished product of example 1

Example 2:

1. soaking the plate ingot: the ingot is subjected to soaking heat preservation for 8 hours at 605 ℃ according to the composition control of the table 3, and then cooled to 550 ℃ for heat preservation for 4 hours.

Table 3 cast ingot composition (wt.%)

Fe	Si	Cu	Mn	Zn	Mg	Ga	Ti	Al％
									0.4356	0.1382	0.0006	0.0006	0.0019	0.0007	0.0091	0.0215	≥99.30

5. Secondary cold rolling: and (3) continuously rolling the aluminum coil subjected to intermediate annealing for 5 times to obtain a 0.25mm cold-rolled coil, wherein the roller roughness is 0.25 mu m, and the rolling speed is 500m/min.

6. Foil rolling: and then carrying out 2-pass foil rolling production, wherein the roller roughness is 0.20um, and the rolling speed is 500m/min, so as to obtain an aluminum foil finished product with the thickness of 0.1mm.

7. Cleaning: and (3) cleaning the finished foil coil, selecting 60# cleaning oil, controlling the cleaning speed to be 100m/min, controlling the temperature of a drying box to be 100 ℃, and ensuring the cleaning and drying of the surface of the cleaned aluminum coil.

8. Shearing: and cutting the cleaned foil roll according to the specification of the width appointed by a customer, wherein the burr at the edge is less than 0.1mm.

9. And (3) annealing a finished product: heating to 300 ℃ by adopting a vacuum annealing furnace (argon) according to 3 hours, preserving heat for 6 hours, controlling vacuum degree to be 45000-50000Pa, discharging and cooling.

10. After finished product annealing is finished, rewinding and checking the surface quality, and checking the mechanical property to obtain the positive aluminum foil finished product for the battery tab, wherein the product has fine and uniform grain structure, average grain size below 40 mu m and grain size series index more than 6 grade, and the tensile strength of the material is improved to 80-90MPa while ensuring the plasticity index. The specific properties are shown in Table 4 below.

TABLE 4 Properties of the Positive electrode aluminum strip finished product of example 2

The beneficial effects of the invention are as follows:

(1) The hot rolling method can effectively avoid the defects of surface quality such as pinholes, peeling and the like caused by the casting and rolling method, and solve the problems of component segregation, uneven distribution of second phase particles and the like.

(2) Pure aluminum Al not less than 99.90% is adopted as a basic raw material, so that the second-phase particle non-uniformity of a low-purity product is reducedThe uniformity is controlled, the content of impurity elements is low, and adverse effects of precipitation of metal compounds on the corrosion resistance and the conductivity of the product are reduced. The electrolyte resistance of the material is more than or equal to 1.7N/mm, and the resistivity is less than or equal to 2.8 x 10 ^-8 Excellent levels of Ω·m.

(3) The method for producing the high-strength, high-plasticity and high-surface tab anode aluminum strip material by adopting a domestic relatively common single-frame hot rolling mill is characterized in that the material surface is clean and smooth, the texture is clear and consistent, and the dyne value is more than or equal to 35 through material heat, cold rolling processing technology and heat treatment technology control. In terms of tissue performance, the grain size series index is more than 6, the tensile strength is 80-90MPa, and the elongation is: 35% (power tab), > 25% (digital tab), bending performance (180 °): a series of technical requirements of more than or equal to 8 times (power lug), more than or equal to 10 times (digital lug), HV hardness of 23-28 and the like.

Claims

1. A manufacturing method of an anode aluminum foil material for a pure aluminum-based battery tab is characterized by comprising the following steps: the battery tab product comprises the following chemical components in percentage by weight: fe:0.43-0.45%, si:0.13-0.16%, cu < 0.01%, mn < 0.005%, zn < 0.005%, mg < 0.005%, ga < 0.01%, ti:0.015-0.025%, other single impurity elements less than 0.01%, and the balance of Al, wherein the content of Al is more than 99.30%; the method adopts semi-continuous casting production cast ingot as a raw material, hot rolling is carried out on the cast ingot, and then cold processing, heat treatment and finishing production are carried out to obtain the anode aluminum foil material for the pure aluminum-based battery tab; the method comprises the following steps:

(1) And (3) hot rolling: carrying out hot rolling on the pure aluminum cast ingot after soaking treatment, wherein the initial hot rolling temperature is 520-560 ℃, the final rolling temperature is 270-300 ℃, the hot rolling passes are 17-21, the rolling reduction rate of the coiling passes is 40-60%, and the hot rolled coiled material with the thickness of 5-7mm is obtained after rolling; the preparation process of the pure aluminum cast ingot comprises the following steps: smelting an aluminum ingot with the purity of more than or equal to 99.90wt.% as a raw material, adding 0.43-0.45wt.% Fe and 0.13-0.16wt.% Si in an aluminum melt, and casting the melt to obtain the pure aluminum ingot, wherein the Al content of the pure aluminum ingot is more than or equal to 99.30wt.%; the soaking treatment process comprises the following steps: soaking and preserving heat for 8 hours at 605 ℃, and then cooling to 550 ℃ and preserving heat for 4 hours; the main purpose of soaking is to eliminate the defects in the casting process and the segregation of components, so that the structure and the components are sufficiently homogenized, and the hot rolling is facilitated; in the hot rolling process, the rolling speed is controlled to be 60-120 m/min;

(3) Intermediate annealing: the intermediate annealing temperature is controlled to be 400-450 ℃, and the heat preservation time is 6-12 h;

(4) The step (3) is subjected to cold rolling for 4-8 times to a thickness of 0.1-0.4 mm finished product after intermediate annealing, and a hard foil coil finished product with a foil surface roughness Ra of 0.15-0.30 mu m is obtained;

(5) Carrying out finished product annealing on the hard foil coil finished product, wherein the finished product annealing temperature is 300-400 ℃, and the heat preservation time is 4-10 hours; annealing the finished product to obtain a soft foil coil finished product with the thickness of 0.1-0.4 mm and the tensile strength of more than or equal to 80 MPa;

the cold rolling reduction ratio between the intermediate annealing and the finished product annealing is more than 80 percent.

2. The method for manufacturing a positive aluminum foil material for a tab of a pure aluminum-based battery according to claim 1, characterized by: and (3) carrying out the annealing process of the finished product in the step (5) after cleaning, drying and shearing the finished product of the hard foil coil obtained after the cold rolling in the step (4).

3. The method for manufacturing a positive aluminum foil material for a tab of a pure aluminum-based battery according to claim 2, characterized by: when the hard foil coil finished product is cleaned, cleaning oil with flash point of 30-70 ℃ and dry point of less than or equal to 220 ℃ is selected, so that the aim of quick volatilization is fulfilled, the cleaning speed is controlled to be 60-100m/min, the foil surface is ensured to be dried, and the residue of the cleaning oil is reduced; controlling the temperature of a drying box to be 90-130 ℃ during drying; transferring the cleaned and dried finished foil roll to a shearing procedure, and cutting according to the specified product width specification, wherein the edge burr is less than 0.1mm; and (5) carrying out the annealing process of the finished product in the step (5) on the foil coil after the cutting.

4. The method for manufacturing a positive aluminum foil material for a tab of a pure aluminum-based battery according to claim 1, characterized by: and (5) in the annealing of the finished product, vacuum annealing is carried out under the protection gas of nitrogen or argon.

5. The method for manufacturing a positive aluminum foil material for a tab of a pure aluminum-based battery according to claim 1, characterized by: the Al content in the positive aluminum foil material for the pure aluminum-based battery tab is more than 99.30wt.%.