阅读说明：本技术 一种动力电池专用型铝箔及其加工工艺 (Special aluminum foil for power battery and processing technology thereof ) 是由 吴保剑 曾元 王毓玮 于 2021-07-14 设计创作，主要内容包括：本发明公开了一种动力电池专用型铝箔及其加工工艺,所述铝箔合金材料配比为：0.2-0.4％Si,1.2-1.3％Fe,0.2-0.3％Cu,0.05-0.1％Zr,0.05-0.1％Ti,0.02-0.05％B,其余为Al和小于0.155％的不可避免杂质；所述的百分比为质量百分比,本发明(1)采用铸轧法生产,省去了常规生产工艺中复杂工艺过程,步骤简单,无污染物产生,绿色环保,同时提高了成材率,节能降耗,提高了铝箔生产质量的水平,(2)采用本发明中的双面等离子清洗方法,可更加准确的控制了成品的厚度,可达到超薄的厚度要求,提高了本方法的实用性,运用范围更广。(The invention discloses a special aluminum foil for a power battery and a processing technology thereof, wherein the aluminum foil comprises the following alloy materials in parts by weight: 0.2-0.4% of Si, 1.2-1.3% of Fe, 0.2-0.3% of Cu, 0.05-0.1% of Zr, 0.05-0.1% of Ti, 0.02-0.05% of B, the balance of Al and inevitable impurities less than 0.155%; the percentage is mass percent, the invention (1) adopts the cast-rolling method to produce, omits the complex process in the conventional production process, has simple steps, no pollutant generation, green and environmental protection, simultaneously improves the yield, saves energy, reduces consumption and improves the production quality level of the aluminum foil, and (2) adopts the double-sided plasma cleaning method in the invention, can more accurately control the thickness of the finished product, can meet the requirement of ultrathin thickness, improves the practicability of the method and has wider application range.)

1. The special aluminum foil for the power battery is characterized in that the aluminum foil alloy material ratio is as follows: 0.2-0.4% of Si, 1.2-1.3% of Fe, 0.2-0.3% of Cu, 0.05-0.1% of Zr, 0.05-0.1% of Ti, 0.02-0.05% of B, the balance of Al and inevitable impurities less than 0.155%; the percentage is mass percentage.

2. The processing technology of the special aluminum foil for the power battery as claimed in claim 1, which is characterized by comprising the following steps:

(1) assembling: connecting the casting and rolling machine with a standing furnace to complete assembly;

(2) smelting, adding aluminum ingot raw materials according to the proportion of alloy materials, melting the raw materials, and adding aluminum-silicon intermediate alloy, aluminum-iron intermediate alloy and copper-aluminum intermediate alloy for component adjustment; smelting raw materials, introducing the smelted raw materials into a standing furnace, and performing modification treatment in the standing furnace; in the process, the smelting temperature reaches 680-plus 700 ℃, the furnace is led to be in a standing furnace after the furnace is led to be in modification treatment, the modification treatment is to add aluminum-zirconium alloy into the standing furnace, and the total amount of the aluminum-zirconium alloy in modification is controlled, so that the zirconium content in the aluminum liquid before casting and rolling is 0.05-0.1%;

(3) casting and rolling: casting and rolling the treated aluminum liquid, and performing secondary modification in a degassing box, wherein the secondary modification is to add aluminum-titanium-boron wires in the degassing box, and control the total amount of aluminum-titanium-boron alloy in modification to ensure that the weight content of titanium in the aluminum liquid before casting and rolling is 0.05-0.1% and the weight content of boron is 0.02-0.05%;

(4) homogenizing and annealing: homogenizing the produced cast-rolled coil, wherein the annealing process comprises the following steps: heating furnace gas at the temperature of 450-;

(5) cold rolling: performing cold rolling and calendering on the homogenized aluminum foil, then trimming, performing cold rolling to a certain thickness, and cooling by adopting rolling oil in the cold rolling process;

(6) cleaning the thickness of the aluminum foil: carrying out double-sided plasma cleaning on the semi-finished product of the aluminum film to obtain the thickness of the aluminum foil required by the finished product;

(7) and (3) finished product detection: detecting the quality and appearance of the aluminum foil which meets the requirements of the finished product after cleaning;

(8) and (4) splitting the finished product, connecting the splitting device with a rolling device, and splitting the finished product after detection.

3. The processing technology of the special aluminum foil for the power battery as claimed in claim 2, wherein the aluminum-zirconium alloy in the step (2) contains 9-11% by weight of zirconium, and the balance of aluminum.

4. The processing technology of the special aluminum foil for the power battery as claimed in claim 2, wherein in the step (3), the aluminum-titanium-boron wire contains 4.5 to 5.5 weight percent of titanium, 0.9 to 1.2 weight percent of boron and the balance of aluminum.

5. The processing technology of the special aluminum foil for the power battery as claimed in claim 2, wherein the viscosity of the rolling oil in the step (5) is as follows: 1.7-2.1(40 ℃ mm2/s), saponification number: 4.0-6.0mgKOH/g, hydroxyl value: 0.05 to 0.1mgKOH/g, acid value: 0.1-0.3 mgKOH/g.

6. The processing technology of the special aluminum foil for the power battery as claimed in claim 2, wherein the annealing process of the finished product in the step (6) is as follows: the temperature of furnace gas is increased by 120 ℃ and 180 ℃ and kept for 4-8 hours, then the temperature of furnace gas is increased by 330 ℃ and 380 ℃ and kept for 6-10 hours, and then the temperature of furnace gas is increased by 150 ℃ and 200 ℃ and kept for 3-5 hours.

7. The processing technology of the power battery special aluminum foil as claimed in claim 2, wherein the reeling device is a 1620mm reeling machine.

Technical Field

The invention relates to a special aluminum foil for a power battery and a processing technology thereof.

Background

New energy automobiles have become a hot spot in world development, wherein the main development directions of the new energy automobiles are hybrid electric vehicles and pure electric vehicles which adopt power lithium ion batteries. In recent years, the power lithium ion battery industry has received high attention and great support from governments around the world. Compared with the traditional battery, the power lithium ion battery has the advantages of high energy density, high working voltage, light weight, small volume, small self-discharge, no memory effect, long cycle life, quick charge and the like, and is called as a green new energy product because of not containing heavy metals such as lead, cadmium and the like. With the development of new energy vehicles and the improvement of energy-saving and environment-friendly requirements, the market space of power lithium ion batteries is further expanded.

The power battery applied to the electric automobile in 2016 is 48.5GWh in the global scale, and is the block with the largest increment among three blocks of consumer electronics, power and energy storage. GGII predicts that the global demand for lithium batteries for electric vehicles will exceed 340GWH by 2022, on a scale 7 times that of 2016.

In 2016, the yield of the Chinese automobile power lithium battery is 30.8GWH, and is increased by 82.2% on a par. With the promotion of lithium battery production technology, cost reduction, increase of popularity of new energy automobiles and supporting facilities and the like in the future, the demand of power batteries of new energy automobiles keeps continuously increasing in the future 3 years, and the GGII predicts that the output of the power lithium batteries of Chinese automobiles reaches 215GWh in 2022 years, which is nearly 6 times higher than that in 2016.

At present, aluminum foil for power batteries, manufacturers of aluminum industry, northeast light alloy and the like of domestic business-inviting bureau and foreign aluminum sheet suppliers all adopt smelting-hot rolling-cold rolling process flows, and the production has the defects of high energy consumption, more flows, low yield and the like. The cast-rolling method for producing the power lithium battery aluminum thin plate is rarely related at home and abroad, and the scheme has high processing technical difficulty and strict production process.

The aluminum foil for the power functional material is used as a current collector of a lithium ion battery, the tensile strength of the aluminum foil must be well controlled, if the tensile strength is too high and the elongation is low, the aluminum foil for the power functional material does not deform enough to adapt to the surface characteristics of an active substance in the process of flattening procedures such as rolling and rolling of an electrode coated with the active substance such as graphite and the like, and the contact performance between the aluminum foil for the power functional material and the active substance is poor; on the contrary, if the electrode coated with the active material has a low tensile strength, the dimensional stability and flatness of the electrode are deteriorated and problems such as breakage are easily caused during the leveling process such as roll rolling. And meanwhile, the elongation rate is enough, and if the elongation rate is low, when the electrode coated with the active substance is subjected to flattening procedures such as roll calendering and the like, the aluminum foil for the power functional material generates internal stress and is split, so that the performances such as battery capacity, cycle life and the like are directly influenced. In general, the lithium ion battery industry uses aluminum foil as the positive electrode of the negative electrode collector, and the thickness of the aluminum foil is different from 10 to 50 microns. The common pure aluminum foil for lithium batteries has the alloy number H18 of 1060, 1050, 8011 and the like, and 1235 alloy is taken as the main alloy material according to the current market situation of the battery foil. The aluminum foil for high-end power functional materials produced by lithium battery production enterprises is mainly produced by aluminum foils for power functional materials produced from hot rolled blanks imported from abroad, and the aluminum foil for high-end power functional materials in China mainly has the quality problems of soft strength, low elongation, insufficient compactness, uneven surface roughness, insufficient surface quality cleanliness and the like compared with the aluminum foil imported from abroad at present. The tensile strength of the aluminum foil of the conventional power battery is generally 190MPa, the elongation is 4 percent, the tensile strength corresponds to the elongation, and the elongation is low when the strength is high.

Disclosure of Invention

The invention aims to solve the defects of the prior art and provides a special aluminum foil for a power battery, which comprises the following aluminum foil alloy materials in parts by weight: 0.2-0.4% of Si, 1.2-1.3% of Fe, 0.2-0.3% of Cu, 0.05-0.1% of Zr, 0.05-0.1% of Ti, 0.02-0.05% of B, the balance of Al and inevitable impurities less than 0.155%; the percentage is mass percentage.

A processing technology of a special aluminum foil for a power battery comprises the following steps:

(1) assembling: and connecting the casting and rolling machine with a standing furnace to complete assembly.

(2) Smelting, adding aluminum ingot raw materials according to the proportion of alloy materials, melting the raw materials, and adding aluminum-silicon intermediate alloy, aluminum-iron intermediate alloy and copper-aluminum intermediate alloy for component adjustment; smelting raw materials, introducing the smelted raw materials into a standing furnace, and performing modification treatment in the standing furnace; in the process, the smelting temperature reaches 680-plus 700 ℃, the furnace is led to be in a standing furnace after the furnace is led to be in modification treatment, the modification treatment is to add aluminum-zirconium alloy into the standing furnace, and the total amount of the aluminum-zirconium alloy in modification is controlled, so that the zirconium content in the aluminum liquid before casting and rolling is 0.05-0.1%;

(3) casting and rolling: casting and rolling the treated aluminum liquid, and performing secondary modification in a degassing box, wherein the secondary modification is to add aluminum-titanium-boron wires in the degassing box, and control the total amount of aluminum-titanium-boron alloy in modification to ensure that the weight content of titanium in the aluminum liquid before casting and rolling is 0.05-0.1% and the weight content of boron is 0.02-0.05%;

(4) homogenizing and annealing: homogenizing the produced cast-rolled coil, wherein the annealing process comprises the following steps: heating furnace gas at the temperature of 450-;

(5) cold rolling: performing cold rolling and calendering on the homogenized aluminum foil, then trimming, performing cold rolling to a certain thickness, and cooling by adopting rolling oil in the cold rolling process;

(6) cleaning the thickness of the aluminum foil: carrying out double-sided plasma cleaning on the semi-finished product of the aluminum film to obtain the thickness of the aluminum foil required by the finished product;

(7) and (3) finished product detection: detecting the quality and appearance of the aluminum foil which meets the requirements of the finished product after cleaning;

(8) and (3) splitting a finished product: and connecting the coil splitting device with the rolling device, and splitting the finished product after detection.

As a further improvement, in the aluminum-zirconium alloy in the step (2), the weight content of zirconium is 9-11%, and the balance is aluminum.

As a further improvement, in the aluminum-titanium-boron wire in the step (3), the weight content of titanium is 4.5-5.5%, the weight content of boron is 0.9-1.2%, and the balance is aluminum.

As a further improvement, the viscosity of the rolling oil in the step (5): 1.7-2.1(40 ℃ mm2/s), saponification number: 4.0-6.0mgKOH/g, hydroxyl value: 0.05 to 0.1mgKOH/g, acid value: 0.1-0.3 mgKOH/g.

As a further improvement, the finished annealing process in the step (6) is as follows: the temperature of furnace gas is increased by 120 ℃ and 180 ℃ and kept for 4-8 hours, then the temperature of furnace gas is increased by 330 ℃ and 380 ℃ and kept for 6-10 hours, and then the temperature of furnace gas is increased by 150 ℃ and 200 ℃ and kept for 3-5 hours.

As a further improvement, the reeling device is a 1620mm reeling machine.

The main added elements in the invention are explained as follows:

si: 0.2 to 0.4% (hereinafter, the content of each component represents wt%) of Si is a main element for refining crystal grains and can reduce the tendency of cracking of the cast plate surface, and in order to obtain the above-mentioned effects, Si is preferably added in an amount of 0.2% or more, but when the content of Si is more than 0.4%, the plasticity of the alloy can be reduced and the alloy is easily broken, so that the Si content is preferably limited to 0.2 to 0.4%.

Fe: 1.2 to 1.3%, the maximum solubility of Fe in aluminum is 0.052%, and when the iron content in aluminum is more than 0.052%, the resultant structure is eutectic of α (Al) and α (Al) + FeCl3, preventing coarsening of the alloy structure, and it is preferable to add 1.2% or more of Fe for obtaining the above effect, but when Fe exceeds 1.3%, the resultant structure is eutectic of primary FeAl3 and α (Al) + FeCl3, and the primary FeAl3 is needle-like or thin-like, hard and brittle, and hardly soluble, and reduces the plasticity of the alloy, so the Fe content is preferably limited to 1.2 to 1.3%.

Cu: 0.2-0.3%, and the addition of copper can reduce the potential difference between the inner crystal and the outer crystal, thereby improving the stress corrosion resistance of the alloy, and simultaneously changing the pitting corrosion into uniform corrosion and reducing the surface roughness of the material, and in order to obtain the effect, more than 0.2% of Cu is preferably added, but when the content of copper is more than 0.3%, a strengthening phase is formed with other elements, and the stress corrosion and the toughness are changed. Therefore, the Cu content is preferably limited to 0.2 to 0.3%.

Zr: 0.05-0.1%, Zr can refine the structure, change the crystal shape of the second phase, form a fine dispersed ZrAl3 dispersed phase to prevent recrystallization and grain growth, and in order to obtain the effect, more than 0.05% of Zr is preferably added, but when the Zr content is higher than 0.1%, Zr provides crystal particles, is difficult to be dissolved, and precipitates in molten aluminum to form defects such as white stripes and the like. Therefore, the Zr content is preferably limited to 0.05 to 0.1%.

Ti: 0.05-0.1 percent of titanium is used as an important process additive and mainly plays a role in refining grains. In order to obtain the above effect, it is preferable to add 0.05% or more, and when the Ti content is higher than 0.1%, coarse Al3Ti is formed in the cast-rolled sheet, and the brittleness of the sheet material is increased. Therefore, the Ti content is preferably limited to 0.05 to 0.1%.

B: 0.02 to 0.05% by mass of TiB2, wherein B is added to refine the as-cast grains and increase the recrystallization temperature, and preferably 0.02% or more of B is added to obtain the above effect, but when the content of B is more than 0.05%, defects such as air passages and inclusions are easily generated. Therefore, the B content is preferably limited to 0.02 to 0.05%.

Has the advantages that:

the method (1) adopts the cast-rolling method for production, omits the complex process in the conventional production process, has simple steps, no pollutant generation, is green and environment-friendly, improves the yield, saves energy, reduces consumption and improves the level of the production quality of the aluminum foil.

(2) By adopting the double-sided plasma cleaning method, the thickness of the finished product can be more accurately controlled, the requirement of ultrathin thickness can be met, the practicability of the method is improved, and the application range is wider.

Detailed Description

For the purpose of enhancing understanding of the present invention, the present invention will be further described in detail with reference to the following examples, which are provided for illustration only and are not to be construed as limiting the scope of the present invention.

Example 1:

smelting an aluminum foil for a high-elongation power battery according to the following weight percentage: si: 0.2%, Fe: 1.22%, Cu: 0.23%, Zr: 0.06%, Ti: 0.05%, B: 0.03 percent, and the balance of impurity elements and aluminum as basic components to prepare raw materials.

The preparation method comprises the following steps:

(1) assembling: connecting the casting and rolling machine with a standing furnace to complete assembly;

(2) smelting: according to the alloy component proportion, the waste is pre-buried at the furnace bottom, the waste can be cleaned, then the aluminum ingot is added, and the aluminum-silicon intermediate alloy, the aluminum-iron intermediate alloy and the copper-aluminum intermediate alloy are added after the raw materials are melted for component adjustment; smelting raw materials, introducing the smelted raw materials into a standing furnace, and performing modification treatment in the standing furnace; in the process, when the smelting temperature reaches 690 ℃, introducing into a furnace, and then carrying out modification treatment in a standing furnace, wherein the modification treatment is to add aluminum-zirconium alloy into the standing furnace, wherein the aluminum-zirconium alloy contains 9.35% of zirconium by weight, and the balance is aluminum; controlling the total amount of aluminum-zirconium alloy in modification to ensure that the zirconium content in the molten aluminum before casting and rolling is 0.06 percent;

(3) casting and rolling: casting and rolling the treated aluminum liquid, and performing secondary modification in a degassing box, wherein the secondary modification is to add an aluminum-titanium-boron wire in the degassing box, wherein the aluminum-titanium-boron wire contains 4.52% of titanium, 1.13% of boron and the balance of aluminum; controlling the total amount of Al-Ti-B alloy in modification to make the titanium content in the molten aluminum before casting and rolling be 0.05% and the boron content be 0.03%;

(4) homogenizing and annealing: the produced cast-rolling coil is firstly subjected to homogenization treatment, and the annealing process comprises the following steps: heating furnace gas at 470 ℃, keeping the temperature of converter gas at 430 ℃ for 6 hours when the metal temperature reaches 430 ℃, and cooling to room temperature after annealing;

(5) cold rolling: carrying out cold rolling and calendering on the homogenized aluminum coil, then cutting edges, carrying out cold rolling to the thickness of a finished product, cooling by adopting rolling oil in the cold rolling process, wherein the viscosity of the rolling oil is as follows: 1.89(40 ℃ mm2/s), saponification number: 5.2mgKOH/g, hydroxyl value: 0.08mgKOH/g, acid value: 0.2 mgKOH/g;

(6) cleaning the thickness of the aluminum foil: carrying out double-sided plasma cleaning on the aluminum film semi-finished product to obtain the aluminum foil thickness required by the finished product, putting the aluminum film semi-finished product into a plasma cleaning station, carrying out double-sided cleaning on the semi-finished product through a plasma cleaning head on the plasma cleaning station to remove trace oxides on the surface, and simultaneously etching the surface in the cleaning process to activate the surface, thereby being beneficial to increasing the surface tension and achieving the thickness required by the finished product;

(7) and (3) finished product detection: detecting the quality and appearance of the aluminum foil which meets the requirements of the finished product after cleaning;

(8) and (3) splitting a finished product: and connecting the coil splitting device with the rolling device, and splitting the finished product after detection.

The aluminum foil for the extension power battery produced according to the steps has the tensile strength of 237MPa and the elongation of 73%.

Example 2:

smelting an aluminum foil for a high-elongation power battery according to the following weight percentage: si: 0.36%, Fe: 1.28%, Cu: 0.23%, Zr: 0.08%, Ti: 0.07%, B: 0.04 percent, and the balance of impurity elements and aluminum as basic components to prepare raw materials.

The preparation method comprises the following steps:

(1) assembling: connecting the casting and rolling machine with a standing furnace to complete assembly;

(2) smelting: according to the alloy component proportion, the waste materials are pre-buried at the furnace bottom, then aluminum ingots are added, and after the raw materials are melted, aluminum-silicon intermediate alloy, aluminum-iron intermediate alloy and copper-aluminum intermediate alloy are added for component adjustment; smelting raw materials, introducing the smelted raw materials into a standing furnace, and performing modification treatment in the standing furnace; in the process, when the smelting temperature reaches 700 ℃, introducing into a furnace, and then performing modification treatment in a standing furnace, wherein the modification treatment is to add aluminum-zirconium alloy into the standing furnace, wherein the aluminum-zirconium alloy contains 9.35 wt% of zirconium and the balance of aluminum; controlling the total amount of aluminum-zirconium alloy in modification to ensure that the zirconium content in the aluminum liquid before casting and rolling is 0.09 percent;

(3) casting and rolling: casting and rolling the treated aluminum liquid, and performing secondary modification in a degassing box, wherein the secondary modification is to add an aluminum-titanium-boron wire in the degassing box, wherein the aluminum-titanium-boron wire contains 4.52% of titanium, 1.13% of boron and the balance of aluminum; controlling the total amount of Al-Ti-B alloy in modification to make the titanium content in the molten aluminum before casting and rolling be 0.1% and the boron content be 0.05%;

(4) homogenizing and annealing: the produced cast-rolling coil is firstly subjected to homogenization treatment, and the annealing process comprises the following steps: heating furnace gas at 490 ℃, keeping the temperature of converter gas at 430 ℃ for 6 hours when the metal temperature reaches 430 ℃, and cooling to room temperature after annealing;

(5) cold rolling: and (3) carrying out cold rolling and calendering on the homogenized aluminum coil, then cutting edges, carrying out cold rolling to the thickness of a finished product, and cooling by adopting rolling oil in the cold rolling process. Viscosity of rolling oil: 1.9(40 ℃ mm2/s), saponification number: 5.5mgKOH/g, hydroxyl value: 0.08mgKOH/g, acid value: 0.2 mgKOH/g;

(6) cleaning the thickness of the aluminum foil: carrying out double-sided plasma cleaning on the aluminum film semi-finished product to obtain the aluminum foil thickness required by the finished product, putting the aluminum film semi-finished product into a plasma cleaning station, carrying out double-sided cleaning on the semi-finished product through a plasma cleaning head on the plasma cleaning station to remove trace oxides on the surface, and simultaneously etching the surface in the cleaning process to activate the surface, thereby being beneficial to increasing the surface tension and achieving the thickness required by the finished product;

(7) and (3) finished product detection: detecting the quality and appearance of the aluminum foil which meets the requirements of the finished product after cleaning;

(8) and (3) splitting a finished product: and connecting the coil splitting device with the rolling device, and splitting the finished product after detection.

The aluminum foil for the extension power battery produced according to the steps has the tensile strength of 248MPa and the elongation of 69 percent.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.