阅读说明：本技术 一种用于正极集流体的高强度铝合金箔及其制备方法 (High-strength aluminum alloy foil for positive current collector and preparation method thereof ) 是由 丁冬雁 朱竞堃 张文龙 高勇进 陈国桢 谢永林 廖永启 聂存珠 唐劲松 于 2021-01-13 设计创作，主要内容包括：本发明涉及锂离子电池正极集流体技术领域,具体涉及到一种用于正极集流体的高强度铝合金箔及其制备方法。其成分包括0.1～0.3wt％的Fe,0.06～0.25wt％的Mn,0.06～0.15wt％的Si,0.1～0.2wt％的La,余量为铝。本发明通过采用合理的成分设计,使得铝合金箔得到了很好的综合性能,兼顾了电导率和力学性能。适量Fe元素的添加提高了铝合金的强度,并且含量的控制能够得到较小尺寸的第二相。少量Mn元素通过固溶强化的形式显著提升合金的抗拉强度,较低的含量使得合金仍然保持较高电导率。Si元素可以在熔炼过程中起到净化杂质的作用,同时会与Fe元素一样以第二相的形式析出,提升力学性能。(The invention relates to the technical field of a positive current collector of a lithium ion battery, in particular to a high-strength aluminum alloy foil for the positive current collector and a preparation method thereof. The alloy comprises 0.1-0.3 wt% of Fe, 0.06-0.25 wt% of Mn, 0.06-0.15 wt% of Si, 0.1-0.2 wt% of La and the balance of aluminum. By adopting reasonable component design, the aluminum alloy foil has good comprehensive performance and both conductivity and mechanical property. The addition of a proper amount of Fe element improves the strength of the aluminum alloy, and the control of the content can obtain a second phase with smaller size. A small amount of Mn element obviously improves the tensile strength of the alloy in a solid solution strengthening mode, and the lower content ensures that the alloy still keeps higher conductivity. The Si element can play a role in purifying impurities in the smelting process, and can be precipitated in a second phase form like the Fe element, so that the mechanical property is improved.)

1. A high-strength aluminum alloy foil is characterized by comprising 0.1-0.3 wt% of Fe, 0.06-0.25 wt% of Mn, 0.06-0.15 wt% of Si, 0.1-0.2 wt% of La and the balance of aluminum.

2. The high-strength aluminum alloy foil as set forth in claim 1, wherein the content of Mn is 0.06 to 0.15 wt%; preferably, the content is 0.08-0.12 wt%.

3. The high-strength aluminum alloy foil as set forth in claim 1, wherein the Si content is 0.08 to 0.12 wt%.

4. The high-strength aluminum alloy foil as set forth in claim 1, wherein the La content is 0.13 to 0.17 wt%.

5. The high-strength aluminum alloy foil as set forth in any one of claims 1 to 4, wherein the high-strength aluminum alloy foil has an electric conductivity of not less than 55% IACS.

6. The high-strength aluminum alloy foil as set forth in claim 5, wherein the high-strength aluminum alloy foil has a tensile strength of not less than 220MPa after heat treatment at 125 ℃ for 5 hours.

7. The method for producing a high-strength aluminum alloy foil according to any one of claims 1 to 6, characterized by comprising the steps of:

(1) smelting an iron-containing raw material, a manganese-containing raw material, a lanthanum-containing raw material and a silicon-containing raw material in a smelting furnace to obtain an aluminum alloy ingot;

(2) keeping the aluminum alloy ingot obtained after smelting at 590-600 ℃ for at least 8-10 hours, and performing homogenization treatment;

(3) and carrying out hot rolling, cold rolling, intermediate annealing and foil rolling on the homogenized material to obtain the product.

8. The method for manufacturing a high-strength aluminum alloy foil according to claim 7, wherein the hot rolling temperature is 460 to 500 ℃ and the reduction is 70 to 85% to obtain a hot-rolled plate.

9. The method for manufacturing a high-strength aluminum alloy foil as recited in claim 7, wherein the hot-rolled sheet is cold-rolled to 0.15mm, and the reduction thereof is 60 to 75%.

10. The use of the high-strength aluminum alloy foil according to any one of claims 1 to 6, which is used for a positive electrode current collector of a lithium ion battery.

Technical Field

The invention relates to the technical field of a positive current collector of a lithium ion battery, in particular to a high-strength aluminum alloy foil for the positive current collector and a preparation method thereof.

Background

The lithium ion battery is one of ideal energy storage devices as a green environment-friendly battery. In addition, the lithium ion battery has the advantages of high energy density, high working voltage, long cycle life, low self-discharge rate, high safety, no memory effect and the like. These advantages make it widely used, from small portable devices such as mobile phones, headsets, notebook computers, cameras to large travel tools such as electric vehicles, see the shadows of lithium ion batteries.

The current collector is one of indispensable components in the lithium ion battery, and mainly functions to support electrode active materials and collect and output charges generated by the active materials after chemical reaction to an external circuit. Although the current collector cannot directly improve the battery capacity, the improvement of the current collector strength can carry more active substances so as to improve the battery specific energy in a phase-change manner. The excellent current collector also needs to have good conductivity, so that the loss in the charge transmission process can be reduced, and the coulombic efficiency, the cycling stability and the rate capability of the battery are improved.

Conductivity is the primary condition to be satisfied, and low conductivity causes charge transmission loss, and meanwhile, the conversion of the lost electric energy into heat causes the internal temperature of the battery to rise, resulting in the reduction of safety and stability. Therefore, most lithium ion batteries mainly use a 1xxxx aluminum alloy having high conductivity as an aluminum alloy foil material for a current collector. However, the series of aluminum alloys have the problem of low strength, and the problems of deformation and fracture which can occur in the coating process are often prevented in a thickening mode. Meanwhile, because of low strength, the series of aluminum alloys can bear limited active substance content under the condition of the same quality, and the energy requirement of the battery is reduced. In addition to this, products in the battery field of today are required to satisfy conditions of high endurance, high portability, and being able to be used in a severer environment, and thus improving the strength of a battery current collector member is one of the demands in the market of today.

Chinese patent CN102747251A adds Fe, Si, Cu and other elements to obtain aluminum foil for lithium ion battery electrode current collector with tensile strength of more than 170MPa and electric conductivity of more than 60.3% IACS after cold rolling. The current collector has high conductivity but general tensile strength, and the patent does not consider the problem of further reduction in strength that may occur after the drying process. Chinese patent CN102978483A discloses an aluminum foil for lithium ion battery positive electrode current collector with strength of over 200MPa after cold rolling by adding Fe, Si, Mn, Mg, Ti, B, etc., but the conductivity is generally about 52% IACS. And the component design of the current collector is complex and is not easy to regulate and control.

Disclosure of Invention

In view of the above technical problems, a first aspect of the present invention provides a high strength aluminum alloy foil, which comprises 0.1 to 0.3 wt% of Fe, 0.06 to 0.25 wt% of Mn, 0.06 to 0.15 wt% of Si, 0.1 to 0.2 wt% of La, and the balance of aluminum.

As a preferable technical scheme, the content of Mn is 0.06-0.15 wt%; preferably, the content is 0.08-0.12 wt%.

As a preferable technical scheme, the content of Si is 0.08-0.12 wt%.

As a preferable technical scheme, the content of the La is 0.13-0.17 wt%.

As a preferable technical scheme, the electric conductivity of the high-strength aluminum alloy foil is not lower than 55% IACS.

As a preferable technical scheme, the tensile strength of the high-strength aluminum alloy foil is not lower than 220MPa after heat treatment for 5 hours at 125 ℃.

A second aspect of the present invention provides a method for manufacturing a high-strength aluminum alloy foil as described above, comprising the steps of:

(1) smelting an iron-containing raw material, a manganese-containing raw material, a lanthanum-containing raw material and a silicon-containing raw material in a smelting furnace to obtain an aluminum alloy ingot;

(2) keeping the aluminum alloy ingot obtained after smelting at 590-600 ℃ for at least 8-10 hours, and performing homogenization treatment;

(3) and carrying out hot rolling, cold rolling, intermediate annealing and foil rolling on the homogenized material to obtain the product.

As a preferable technical scheme, the hot rolling temperature is 460-500 ℃, and the reduction is 70-85%, so that the hot rolled plate is obtained.

As a preferable technical scheme, the hot rolled plate is cold rolled to 0.15mm, and the reduction is 60-75%.

The third aspect of the invention provides the application of the high-strength aluminum alloy foil as described above to the positive electrode current collector of the lithium ion battery.

Has the advantages that: by adopting reasonable component design, the aluminum alloy foil has good comprehensive performance and both conductivity and mechanical property. The addition of a proper amount of Fe element improves the strength of the aluminum alloy, and the control of the content can obtain a second phase with smaller size. A small amount of Mn element obviously improves the tensile strength of the alloy in a solid solution strengthening mode, and the lower content ensures that the alloy still keeps higher conductivity. The Si element can play a role in purifying impurities in the smelting process, and can be precipitated in a second phase form like the Fe element, so that the mechanical property is improved. The addition of the La element can refine alloy grains, promote the spheroidization precipitation of a second phase, inhibit irregular massive Fe-containing precipitated phases and generate an Al-Fe-La new phase to further strengthen the alloy. Besides, the La element can also improve the corrosion resistance of the alloy, so that the current collector has better stability in electrolyte.

Detailed Description

The technical features of the technical solutions provided by the present invention will be further clearly and completely described below with reference to the specific embodiments, and it should be apparent that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The words "preferred", "preferably", "more preferred", and the like, in the present invention, refer to embodiments of the invention that may provide certain benefits, under certain circumstances. However, other embodiments may be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

It should be understood that other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term "about".

The invention provides a high-strength aluminum alloy foil, and aims to provide an aluminum alloy foil for a positive electrode current collector with high conductivity and high strength, and the current collector can meet the requirement of maintaining high tensile strength after being dried by heat treatment at 125 ℃. The current collector can be used for replacing the common aluminum alloy foil for the low-strength positive current collector. Finally obtaining the aluminum alloy foil for the positive current collector with the tensile strength of more than 220MPa and the electric conductivity of more than 55% IACS after heat treatment at different temperatures.

Specifically, the high-strength aluminum alloy foil comprises 0.1-0.3 wt% of Fe, 0.06-0.25 wt% of Mn, 0.06-0.15 wt% of Si, 0.1-0.2 wt% of La, and the balance of aluminum and other inevitable impurities.

In some preferred embodiments, the Mn (manganese) content is 0.06 to 0.15 wt%; preferably, the content is 0.08-0.12 wt%.

In some preferred embodiments, the Si (silicon) content is 0.08 to 0.12 wt%.

In some preferred embodiments, the La (lanthanum) is present in an amount of 0.13 to 0.17 wt%.

As a preferable technical solution, the electric conductivity of the high-strength aluminum alloy foil is not less than 55% IACS; more preferably, the high-strength aluminum alloy foil has a tensile strength of not less than 220MPa after heat treatment at 125 ℃ for 5 hours.

In the invention, the source of each component in the high-strength aluminum alloy foil is not specially limited, and various alloys containing the specific components, pure metals and other components can be adopted; preferably, an aluminum alloy containing the above-mentioned specific composition is used. Including but not limited to Al (75 wt%) -Fe, Al (80 wt%) -Mn, Al (20 wt%) -La master alloys, etc.

A second aspect of the present invention provides a method for manufacturing a high-strength aluminum alloy foil as described above, comprising the steps of:

(1) smelting an iron-containing raw material, a manganese-containing raw material, a lanthanum-containing raw material and a silicon-containing raw material in a smelting furnace to obtain an aluminum alloy ingot;

(2) keeping the aluminum alloy ingot obtained after smelting at 590-600 ℃ for at least 8-10 hours, and performing homogenization treatment;

(3) hot rolling the homogenized material (preferably at a hot rolling temperature of 460-500 ℃ and a reduction of 70-85%), cold rolling (preferably to a cold rolling thickness of 0.15mm and a reduction of 60-75%), intermediate annealing (preferably to an intermediate annealing of the cold-rolled sheet at 300-350 ℃ for 2 hours), and foil rolling.

In some embodiments, it comprises the steps of:

(1) firstly, melting an industrial aluminum ingot, and sequentially adding an intermediate alloy of Al-75 wt% of Fe, Al-80 wt% of Mn and Al-20 wt% of La and Si in a smelting furnace according to the proportion. Controlling the content of Fe: 0.1 to 0.3 wt%, Mn: 0.06-0.15 wt%, Si: 0.06-0.15 wt%, La: 0.1 to 0.2 wt%, the balance being aluminum and other unavoidable impurities. Wherein the preferable weight ratio of manganese is as follows: 0.08-0.12 wt%, and the preferable weight ratio of silicon is as follows: 0.08 to 0.12 wt%.

(2) Homogenizing the obtained aluminum alloy cast ingot, wherein the temperature is set to be 590-600 ℃, and the heat preservation time is 8-10 hours. After the homogenization treatment, hot rolling is carried out, wherein the hot rolling is carried out at a temperature of 460 to 500 ℃ with a rolling reduction of 70 to 85% controlled, and the thickness is about 3 mm.

(3) And (3) cold rolling the hot rolled plate to 0.15mm, and controlling the reduction amount to be 60-75%.

(4) And finally, performing intermediate annealing on the cold-rolled sheet at 300-350 ℃ for 2 hours, and then rolling the foil with the processing rate of more than 40% to obtain the aluminum alloy foil with the thickness of 0.05-0.08 mm.

According to the invention, the addition of Si and Fe can improve the strength of the aluminum alloy, and the Si can play a role in purifying impurities in the smelting process. Since Fe has a low solid solubility in aluminum matrix and is mostly precipitated as a second phase, Fe is mainly precipitated by Al₃The Fe second phase strengthening mechanism improves the strength of the alloy. The strength of the alloy can be enhanced by adding proper amounts of Fe and Si, but excessive addition of Fe can cause the size of precipitated second phases to be larger, and large-sized hard second phases such as Al₃Fe、Al₉Fe₂Si₂This causes toughness-reducing rolling difficulties and these hard second phases are liable to act as crack sources to cause bulk fracture. Therefore, the size of the second phase is controlled by regulating the contents of the iron element and the silicon element, so that the strength of the aluminum alloy foil is improved, and the preparation difficulty is reduced.

In addition, a certain amount of Mn element and La element are introduced into the high-strength aluminum alloy foil, and the solubility of the Mn element in an Al matrix is obviously higher than that of Fe, so that the tensile strength of the alloy is improved mainly through a solid solution strengthening mechanism. The addition of Mn element has obvious effect on improving the strength of the alloy, but the influence on the conductivity is also very obvious, and the excessive doping can cause the rapid reduction of the conductivity, so the excessive addition can not be carried out. The content of manganese is regulated and controlled, so that the strength of the aluminum alloy foil is improved on the basis of ensuring the conductivity. Moreover, the introduction of the trace rare earth element La can refine alloy grains, promote the precipitation of a second phase in a fine spherical form, and generate a new Al-Fe-La phase to further strengthen the alloy. Meanwhile, the method avoids using a large amount of other element components such as Mg, Ti, Zn, V and the like, and effectively avoids the problems that the alloy components are more complicated to regulate and control, are not easy to control in the smelting and casting process and the like due to the addition of the elements.

The third aspect of the invention provides the application of the high-strength aluminum alloy foil as described above to the positive electrode current collector of the lithium ion battery.

The present invention will be specifically described below by way of examples. It should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and that the insubstantial modifications and adaptations of the present invention by those skilled in the art based on the above disclosure are still within the scope of the present invention.

Examples

Example 1: the embodiment provides a high-strength aluminum alloy foil, and a preparation method thereof comprises the following steps:

(1) firstly, melting an industrial aluminum ingot, sequentially adding Al (75 wt%) -Fe, Al (80 wt%) -Mn, Al (20 wt%) -La intermediate alloy and Si in a smelting furnace according to the above proportion, smelting and casting to obtain an alloy ingot with the thickness of 22 mm. Controlling the content of Fe: 0.25 wt%, Mn: 0.1 wt%, Si: 0.1 wt%, La: 0.1 wt%, the balance being aluminum and other unavoidable impurities.

(2) Homogenizing the obtained aluminum alloy ingot, setting the temperature at 595 ℃, and keeping the temperature for 9 hours. After the homogenization treatment, hot rolling is carried out to a thickness of about 3mm at 480 ℃ with a rolling reduction of about 80%.

(3) Cold rolling the hot rolled plate, finally, carrying out intermediate annealing on the cold rolled plate at 330 ℃ for 2 hours, and then carrying out foil rolling with the working ratio of more than 40% to obtain the aluminum alloy foil with the thickness of about 0.07 mm.

Example 2: the embodiment provides a high-strength aluminum alloy foil, and a preparation method thereof comprises the following steps:

(1) firstly, melting an industrial aluminum ingot, sequentially adding Al (75 wt%) -Fe, Al (80 wt%) -Mn, Al (20 wt%) -La intermediate alloy and Si in a smelting furnace according to the above proportion, smelting and casting to obtain an alloy ingot with the thickness of 22 mm. Controlling the content of Fe: 0.25 wt%, Mn: 0.1 wt%, Si: 0.1 wt%, La: 0.15 wt%, the balance being aluminium and other unavoidable impurities.

(2) Homogenizing the obtained aluminum alloy ingot, setting the temperature at 595 ℃, and keeping the temperature for 9 hours. After the homogenization treatment, hot rolling is carried out to a thickness of about 3mm at 480 ℃ with a rolling reduction of about 80%.

(3) Cold rolling the hot rolled plate, finally, carrying out intermediate annealing on the cold rolled plate at 330 ℃ for 2 hours, and then carrying out foil rolling with the working ratio of more than 40% to obtain the aluminum alloy foil with the thickness of about 0.08 mm.

Example 3: the embodiment provides a high-strength aluminum alloy foil, and a preparation method thereof comprises the following steps:

(1) firstly, melting an industrial aluminum ingot, sequentially adding Al (75 wt%) -Fe, Al (80 wt%) -Mn, Al (20 wt%) -La intermediate alloy and Si in a smelting furnace according to the above proportion, smelting and casting to obtain an alloy ingot with the thickness of 22 mm. Controlling the content of Fe: 0.15 wt%, Mn: 0.1 wt%, Si: 0.1 wt%, La: 0.1 wt%, the balance being aluminum and other unavoidable impurities.

(2) Homogenizing the obtained aluminum alloy ingot, setting the temperature at 595 ℃, and keeping the temperature for 9 hours. After the homogenization treatment, hot rolling is carried out to a thickness of about 3mm at 480 ℃ with a rolling reduction of about 80%.

(3) Cold rolling the hot rolled plate, finally, carrying out intermediate annealing on the cold rolled plate at 330 ℃ for 2 hours, and then carrying out foil rolling with the working ratio of more than 40% to obtain the aluminum alloy foil with the thickness of about 0.07 mm.

Example 4: this embodiment provides a high strengthThe preparation method of the aluminum alloy foil comprises the following steps:

(1) firstly, melting an industrial aluminum ingot, sequentially adding Al (75 wt%) -Fe, Al (80 wt%) -Mn, Al (20 wt%) -La intermediate alloy and Si in a smelting furnace according to the above proportion, smelting and casting to obtain an alloy ingot with the thickness of 22 mm. Controlling the content of Fe: 0.15 wt%, Mn: 0.1 wt%, Si: 0.1 wt%, La: 0.15 wt%, the balance being aluminium and other unavoidable impurities.

(2) Homogenizing the obtained aluminum alloy ingot, setting the temperature at 595 ℃, and keeping the temperature for 9 hours. After the homogenization treatment, hot rolling is carried out to a thickness of about 3mm at 480 ℃ with a rolling reduction of about 80%.

(3) Cold rolling the hot rolled plate, finally, carrying out intermediate annealing on the cold rolled plate at 330 ℃ for 2 hours, and then carrying out foil rolling with the working ratio of more than 40% to obtain the aluminum alloy foil with the thickness of about 0.07 mm.

Comparative example 1: this comparative example provides an aluminum alloy foil, prepared mainly according to the technical disclosure disclosed in chinese patent CN102747251A, having the composition si 0.03wt%, fe 0.20wt%, cu 0.005wt%, and balance aluminum, prepared in the manner described in the patent document.

Comparative example 2: the present comparative example provides an aluminum alloy foil, which is prepared mainly according to the technical content disclosed in chinese patent CN102978483A, and has the composition of Si 0.30 wt%, Fe 1.58 wt%, Mn 0.21 wt%, Mg 0.25 wt%, B0.004 wt%, Ti 0.02 wt%, and the balance aluminum, and is prepared according to the manner described in the patent document.

Comparative example 3: this comparative example provides an aluminum alloy foil having specific compositions including 0.20 wt% Si, 0.04wt% Cu0.04wt%, 0.25 wt% Fe, 0.03 wt% Mn, 0.03 wt% Mg, 0.03 wt% Ti, 0.05 wt% V, 0.04 wt% Zn, and the balance aluminum, prepared according to the method of example 1 of the present application, using 1070 aluminum alloy.

The tensile strength, elongation and electric conductivity of the aluminum alloy foil having the above composition were measured by the applicant, and the results are shown in table 1.

The performance tests performed on the aluminum alloy samples of different compositions in the above examples and comparative examples were as follows:

(1) room temperature tensile test: preparing a standard tensile sample according to the national standard GB/T228-2002, stretching on a Zwick Z20 universal tensile testing machine, wherein the stretching speed is 1mm/min, the length of an extensometer is 40mm, and measuring the tensile strength and the elongation; the tensile sample for testing was obtained by cutting an aluminum alloy foil in the rolling direction.

(2) And (3) conductivity test: and testing the conductivity of the aluminum alloy sample by using an SIGMATEST 2.069.069 conductivity measuring instrument.

Table 1 table of performance test results

From the above experimental results, in examples 1 to 4, good alloy foil performance test results were obtained: the conductive adhesive has high conductivity (not less than 55% IACS), and also has high tensile strength after being dried by heat treatment, wherein the tensile strength is more than 220MPa, and can reach 258MPa at most, which is more than that of comparative examples 1, 2 and 3. The invention realizes the improvement of comprehensive performance, can bear more active substances on the basis of high conductivity, and can still ensure the stability of mechanical property in the high-temperature drying process.

According to the invention, the reasonable component design is adopted, so that the embodiment obtains good comprehensive performance, and the conductivity and the mechanical property are considered. The addition of a proper amount of Fe element improves the strength of the aluminum alloy, and the control of the content can obtain a second phase with smaller size. A small amount of Mn element obviously improves the tensile strength of the alloy in a solid solution strengthening mode, and the lower content ensures that the alloy still keeps higher conductivity. The Si element can play a role in purifying impurities in the smelting process, and can be precipitated in a second phase form like the Fe element, so that the mechanical property is improved. The addition of the La element can refine alloy grains, promote the spheroidization precipitation of a second phase, inhibit irregular massive Fe-containing precipitated phases and generate an Al-Fe-La new phase to further strengthen the alloy. Besides, the La element can also improve the corrosion resistance of the alloy, so that the current collector has better stability in electrolyte.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in other forms, and any person skilled in the art may modify or change the technical content of the above disclosure into equivalent embodiments with equivalent changes, but all those simple modifications, equivalent changes and modifications made to the above embodiments according to the technical spirit of the present invention still belong to the protection scope of the present invention.