Energy-saving battery aluminum foil and method for manufacturing the same

Abstract

The application provides an energy-saving battery aluminum foil and a preparation method thereof, and comprises the following steps: smelting: smelting according to the 1235 alloy, and performing slagging treatment by using a slagging agent and a refining agent; heat preservation: controlling the temperature of aluminum liquid at 700 DEG C ± 5 DEG C, adding modification treatment in a heat preservation furnace, the modification treatment is adding an aluminum strontium alloy into the heat preservation furnace, and stirring by using an electromagnetic stirring device, refining once every 30 minutes by using a refining agent, and then performing slagging treatment; hydrogen removal: using argon as a hydrogen removal medium in a degassing box to perform online hydrogen removal, and adding an Al-Ti-B-RE alloy wire rod in the degassing box; casting and rolling: performing casting and rolling in a casting and rolling machine; cold rolling: performing cold rolling on the cast and rolled plate; heat treatment: performing heat treatment on the cold rolled plate to a thickness of 1.0 mm, and performing cold rolling to a finished product; and performing corona treatment to obtain the energy-saving battery aluminum foil. The energy-saving battery aluminum foil has a tensile strength of greater than or equal to 256 MPa, an elongation of greater than or equal to 8%, a pinhole number of less than or equal to 3 / m, a dyne value of greater than or equal to 34 dyn, and is an energy-saving battery aluminum foil with high strength, high elongation, and low breakage rate. 2 ​

Description

Technical Field

[0001] This invention belongs to the technical field of battery aluminum foil preparation methods, specifically an energy-saving battery aluminum foil and its preparation method. Background Technology

[0002] Aluminum foil for batteries is commonly used as a current collector in the positive electrode of lithium-ion batteries. Its thickness is required to be controlled between 10μm and 15μm. Compared to ordinary aluminum foil, the requirements for battery current collector foil are higher. While continuously reducing thickness, it also requires lower roughness, better conductivity, tensile strength, and elongation. Furthermore, high requirements are placed on product consistency and stability. Therefore, battery aluminum foil has high requirements for equipment and processes, is more difficult to process, has the highest added value among all aluminum foil products, and possesses certain barriers to entry.

[0003] Currently, the aluminum alloys used in China for manufacturing battery aluminum foil are mainly high-purity alloys such as 1060 and 1100, and are mostly made from remelted aluminum ingots. 1235 alloy, due to its relatively high impurity content, is used less frequently for battery aluminum foil. In existing technology, 1235 battery aluminum foil typically has a tensile strength of 220 MPa, an elongation of 4%, and a pinhole count of 10 per meter. 2 The dyn value is 32 dyn, and the main defects currently exist: during the process of cold-rolled billets being transported to downstream customers for subsequent battery foil processing, the main technical problems of 1235 battery aluminum foil are strip breakage and low elongation, excessive pinholes and bright crystal defects in battery aluminum foil. Summary of the Invention

[0004] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the purpose of this invention is to provide a method for preparing energy-saving battery aluminum foil. Another purpose of this invention is to provide an energy-saving battery aluminum foil with high strength, low breakage rate and high elongation rate prepared by this method.

[0005] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0006] A method for preparing aluminum foil for energy-saving batteries includes the following steps:

[0007] Step (a) Smelting: Smelt according to the 1235 alloy, and use slag remover and refining agent for slag removal treatment. The smelting temperature is controlled at 700℃ and the furnace pouring temperature is controlled at 710℃.

[0008] Step (b) Heat preservation: The temperature of the aluminum liquid is controlled at 700℃±5℃. A modification treatment is added to the heat preservation furnace. The modification treatment is to add aluminum-strontium alloy to the heat preservation furnace and stir it with electromagnetic stirring. Every 30 minutes, it is refined with a refining agent and then the slag is removed.

[0009] Step (c) Hydrogen removal: Argon gas is used as the hydrogen removal medium in the degassing box for online hydrogen removal. At the same time, Al-Ti-B-RE alloy wire is added to the degassing box, and the temperature of the aluminum liquid is controlled at 685℃±3℃.

[0010] Step (d) Casting and rolling: Casting and rolling are carried out in the casting and rolling mill. The temperature of the front box is controlled at 682±2℃, the casting and rolling zone is 18-32mm, the casting and rolling speed is 1600-1800mm / min, and the thickness of the cast and rolled plate is 4.3-5.2mm.

[0011] Step (e) Cold rolling: The cast-rolled plate is cold rolled at a speed of 650-720 m / min;

[0012] Step (f) Heat treatment: Cold rolled to a thickness of 1.0 mm and then heat treated. The heat treatment process is as follows: first, treat at 360℃ for 8 hours, then treat at 340℃ for 12 hours. Specifically: heat at 360℃ for 4 hours, then hold for 4 hours, then heat at 340℃ for 4 hours, then hold for 8 hours.

[0013] Step (g) Cold rolling to finished product: Cold roll the cast-rolled plate to a finished size of 0.12-0.18 mm;

[0014] Step (h) Corona treatment: The aluminum foil surface is corona treated using a corona equipment and kept at 42-43℃ for 8-10 hours in a closed environment to obtain energy-saving battery aluminum foil.

[0015] Preferably, the slag remover in step (a) comprises the following substances in parts by weight: 40-43 parts silicon dioxide, 20-25 parts aluminum chloride, 15-18 parts potassium chloride, 5-8 parts sodium chloride, 1-3 parts calcium fluoride, 5-6 parts iron oxide, and 1 part potassium nitrate; the mass ratio of the slag remover to the molten aluminum alloy is 1-2:3000, which removes the aluminum slag from the molten aluminum, improves the cleanliness of the molten aluminum, and increases the lifespan of the tubular filtration system.

[0016] Preferably, the refining agent in step (a) comprises the following substances in parts by weight: 40-50 parts of chloride auxiliaries, 15-20 parts of potassium fluoroaluminate, 10-12 parts of light carbonic acid, 1-2 parts of charcoal powder, 3-5 parts of hexachloroethane, 10-12 parts of sodium sulfate, and 5-8 parts of potassium chloride; the mass ratio of the refining agent to the aluminum alloy melt is 1:2000.

[0017] Preferably, in step (b), the refining agent is carbon tetrachloride liquid, and the mass ratio of the refining agent to the aluminum alloy melt is 1:8000.

[0018] Preferably, the strontium content in step (b) is controlled at 0.4-0.8%.

[0019] Preferably, the amount of Al-Ti-B-RE alloy wire added in step (c) is 0.8 kg / t to 1.2 kg / t.

[0020] An energy-saving battery aluminum foil, prepared according to the energy-saving battery aluminum foil preparation method.

[0021] The energy-saving battery aluminum foil has a tensile strength ≥256MPa, an elongation ≥8%, and a pinhole count ≤3 / m. 2 The dyn value is ≥34dyn.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. This invention uses liquid carbon tetrachloride as a refining agent in a holding furnace for refining. Impurities are easily adsorbed and aggregated by carbon tetrachloride and float on the surface of the molten aluminum, improving the refining effect. At the same time, compared with solid refining agents, it reduces the contamination of the melt by the refining agent, laying the foundation for a smaller number of pinholes in the subsequent process.

[0024] 2. This invention utilizes a novel grain refiner, Al-Ti-B-RE alloy wire. Since rare earth elements are surface-active substances, they readily adsorb and agglomerate at the grain boundaries and phase surfaces of aluminum, filling defects on the crystal surfaces and thus hindering the aggregation of TiB2 and TiAl3, thereby refining TiB2 and TiAl3. Therefore, the cast-rolled plate exhibits uniform and fine grains. Al-Ti-B-RE can essentially eliminate TiB2 precipitation, demonstrating a significant grain refinement effect, long-lasting efficacy, low addition amount, good heritability, and strong high-temperature resistance.

[0025] 3. This invention uses a small casting and rolling zone, a thinner casting and rolling plate, and rapid casting and rolling, which makes the cooling rate of the casting and rolling plate uniform, improves the quality of the casting and rolling plate, and provides a guarantee for the high elongation rate of the subsequent battery aluminum foil.

[0026] 4. The energy-saving battery aluminum foil prepared by the method of this invention has a tensile strength ≥256MPa, an elongation ≥8%, and a pinhole count ≤3 / m. 2 With a dyn value ≥34dyn, it is an energy-saving battery aluminum foil with high strength, low breakage rate, and high elongation.

[0027] Note that the description of these effects does not preclude the existence of other effects. One aspect of the invention does not necessarily have all the aforementioned effects. Effects other than those described above can be readily observed and extracted from the description, drawings, claims, etc. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the preparation method of the energy-saving battery aluminum foil of the present invention. Detailed Implementation

[0029] The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and should not be used to limit the scope of protection of the present invention. Furthermore, unless otherwise specified, the preparation processes in the following embodiments are all conventional methods in the prior art, and therefore will not be described in detail; unless otherwise specified, the raw materials used in the following embodiments are all commercially available products.

[0030] Example 1

[0031] like Figure 1 As shown, a method for preparing aluminum foil for energy-saving batteries includes the following steps:

[0032] Step (a) Smelting: Smelt according to the 1235 alloy, and use slag remover and refining agent for slag removal treatment. The smelting temperature is controlled at 700℃ and the furnace pouring temperature is controlled at 710℃.

[0033] Step (b) Heat preservation: The temperature of the aluminum liquid is controlled at 697℃. A modification treatment is added to the heat preservation furnace. The modification treatment is to add aluminum-strontium alloy to the heat preservation furnace and stir it with electromagnetic stirring. Every 30 minutes, it is refined with a refining agent and then the slag is removed.

[0034] Step (c) Hydrogen removal: Argon gas is used as the hydrogen removal medium in the degassing box for online hydrogen removal. At the same time, Al-Ti-B-RE alloy wire is added to the degassing box, and the temperature of the aluminum liquid is controlled at 684℃.

[0035] Step (d) Casting and rolling: Casting and rolling are carried out in the casting and rolling mill, with the front box temperature controlled at 681℃, the casting and rolling zone 18mm, the casting and rolling speed 1600mm / min, and the casting and rolling plate thickness 4.3mm.

[0036] Step (e) Cold rolling: The cast-rolled plate is cold rolled at a speed of 655 m / min;

[0037] Step (f) Heat treatment: Cold rolled to a thickness of 1.0 mm and then heat treated. The heat treatment process is to first treat at 360℃ for 8 hours, and then treat at 340℃ for 12 hours. Specifically: heat at 360℃ for 4 hours, then hold for 4 hours, then heat at 340℃ for 4 hours, and then hold for 8 hours.

[0038] Step (g) Cold rolling to finished product: Cold roll the cast-rolled plate to a finished size of 0.12 mm;

[0039] Step (h) Corona treatment: The aluminum foil surface is corona treated using a corona equipment and kept at 42℃ for 8 hours in a closed environment.

[0040] The slag remover in step (a) comprises the following substances in parts by weight: 40 parts silicon dioxide, 25 parts aluminum chloride, 18 parts potassium chloride, 8 parts sodium chloride, 2 parts calcium fluoride, 6 parts iron oxide, and 1 part potassium nitrate; the mass ratio of the slag remover to the molten aluminum alloy is 1:3000.

[0041] The refining agent in step (a) includes the following substances in parts by weight: 48 parts of chloride auxiliaries, 19 parts of potassium fluoroaluminate, 11 parts of light carbonic acid, 1 part of charcoal powder, 4 parts of hexachloroethane, 10 parts of sodium sulfate, and 7 parts of potassium chloride; the mass ratio of the refining agent to the aluminum alloy melt is 1:2000.

[0042] In step (b), the refining agent is carbon tetrachloride liquid. The mass ratio of the refining agent to the aluminum alloy melt is 1:8000, and the strontium content is controlled at 0.45%.

[0043] In step (c), the amount of Al-Ti-B-RE alloy wire added is 0.8 kg / t.

[0044] The energy-saving battery aluminum foil prepared according to Example 1 has a tensile strength of 264 MPa, an elongation of 10%, and a pinhole count of 3 / m. 2 The dyn value is 36 dyn, which shows that the energy-saving battery aluminum foil prepared by the present invention has high tensile strength and elongation, is not easy to break, has low pinhole count, and has a high dyn value.

[0045] Example 2

[0046] like Figure 1 As shown, a method for preparing aluminum foil for energy-saving batteries includes the following steps:

[0047] Step (a) Smelting: Smelt according to the 1235 alloy, and use slag remover and refining agent for slag removal treatment. The smelting temperature is controlled at 700℃ and the furnace pouring temperature is controlled at 710℃.

[0048] Step (b) Heat preservation: The temperature of the aluminum liquid is controlled at 702℃. A modification treatment is added to the heat preservation furnace. The modification treatment is to add aluminum-strontium alloy to the heat preservation furnace and stir it with electromagnetic stirring. Every 30 minutes, it is refined with a refining agent and then the slag is removed.

[0049] Step (c) Hydrogen removal: Argon gas is used as the hydrogen removal medium in the degassing box for online hydrogen removal. At the same time, Al-Ti-B-RE alloy wire is added to the degassing box, and the temperature of the aluminum liquid is controlled at 686℃.

[0050] Step (d) Casting and rolling: Casting and rolling are carried out in the casting and rolling mill, with the front box temperature controlled at 682℃, the casting and rolling zone 24mm, the casting and rolling speed 1700mm / min, and the casting and rolling plate thickness 4.8mm.

[0051] Step (e) Cold rolling: The cast-rolled plate is cold rolled at a speed of 690 m / min;

[0052] Step (f) Heat treatment: Cold rolled to a thickness of 1.0 mm and then heat treated. The heat treatment process is as follows: first, treat at 360℃ for 8 hours, then treat at 340℃ for 12 hours. Specifically: heat at 360℃ for 4 hours, then hold for 4 hours, then heat at 340℃ for 4 hours, then hold for 8 hours.

[0053] Step (g) Cold rolling to finished product: Cold roll the cast-rolled plate to a finished size of 0.13 mm;

[0054] Step (h) Corona treatment: The aluminum foil surface is corona treated using a corona equipment and kept at 42℃ for 9 hours in a closed environment.

[0055] The slag remover in step (a) comprises the following substances in parts by weight: 43 parts silicon dioxide, 24 parts aluminum chloride, 18 parts potassium chloride, 8 parts sodium chloride, 1 part calcium fluoride, 5 parts iron oxide, and 1 part potassium nitrate; the mass ratio of the slag remover to the molten aluminum alloy is 1.5:3000.

[0056] The refining agent in step (a) includes the following substances in parts by weight: 46 parts of chloride auxiliaries, 18 parts of potassium fluoroaluminate, 11 parts of light carbonic acid, 2 parts of charcoal powder, 5 parts of hexachloroethane, 11 parts of sodium sulfate, and 7 parts of potassium chloride; the mass ratio of the refining agent to the aluminum alloy melt is 1:2000.

[0057] In step (b), the refining agent is made of liquid carbon tetrachloride. The mass ratio of the refining agent to the aluminum alloy melt is 1:8000, and the strontium content is controlled at 0.56%.

[0058] In step (c), the amount of Al-Ti-B-RE alloy wire added is 1.0 kg / t.

[0059] The energy-saving battery aluminum foil prepared according to Example 2 has a tensile strength of 268 MPa, an elongation of 12%, and a pinhole count of 2 / m. 2 The dyn value is 36 dyn, which shows that the energy-saving battery aluminum foil prepared by the present invention has high tensile strength and elongation, is not easy to break, has low pinhole count, and has a high dyn value.

[0060] Example 3

[0061] like Figure 1 As shown, a method for preparing aluminum foil for energy-saving batteries includes the following steps:

[0062] Step (a) Smelting: Smelt according to the 1235 alloy, and use slag remover and refining agent for slag removal treatment. The smelting temperature is controlled at 700℃ and the furnace pouring temperature is controlled at 710℃.

[0063] Step (b) Heat preservation: The temperature of the aluminum liquid is controlled at 704℃. A modification treatment is added to the heat preservation furnace. The modification treatment is to add aluminum-strontium alloy to the heat preservation furnace and stir it with electromagnetic stirring. Every 30 minutes, it is refined with a refining agent and then the slag is removed.

[0064] Step (c) Hydrogen removal: Argon gas is used as the hydrogen removal medium in the degassing box for online hydrogen removal. At the same time, Al-Ti-B-RE alloy wire is added to the degassing box, and the temperature of the aluminum liquid is controlled at 687℃.

[0065] Step (d) Casting and rolling: Casting and rolling are carried out in the casting and rolling mill, with the front box temperature controlled at 683℃, the casting and rolling zone 28mm, the casting and rolling speed 1800mm / min, and the casting and rolling plate thickness 5.1mm.

[0066] Step (e) Cold rolling: The cast-rolled plate is cold rolled at a speed of 712 m / min;

[0067] Step (f) Heat treatment: Cold rolled to a thickness of 1.0 mm and then heat treated. The heat treatment process is as follows: first, treat at 360℃ for 8 hours, then treat at 340℃ for 12 hours. Specifically: heat at 360℃ for 4 hours, then hold for 4 hours, then heat at 340℃ for 4 hours, then hold for 8 hours.

[0068] Step (g) Cold rolling to finished product: Cold roll the cast-rolled plate to a finished size of 0.16 mm;

[0069] Step (h) Corona treatment: The aluminum foil surface is corona treated using a corona equipment and kept at 43℃ for 10 hours in a closed environment;

[0070] The slag remover in step (a) comprises the following components by weight: 43 parts silicon dioxide, 24 parts aluminum chloride, 18 parts potassium chloride, 7 parts sodium chloride, 2 parts calcium fluoride, 5 parts iron oxide, and 1 part potassium nitrate; the mass ratio of the slag remover to the molten aluminum alloy is 2:3000.

[0071] The refining agent in step (a) includes the following substances in parts by weight: 43 parts chloride auxiliaries, 20 parts potassium fluoroaluminate, 12 parts light carbonic acid, 2 parts charcoal powder, 4 parts hexachloroethane, 11 parts sodium sulfate, and 8 parts potassium chloride; the mass ratio of the refining agent to the aluminum alloy melt is 1:2000.

[0072] In step (b), the refining agent is carbon tetrachloride liquid. The mass ratio of the refining agent to the aluminum alloy melt is 1:8000, and the strontium content is controlled at 0.62%.

[0073] In step (c), the amount of Al-Ti-B-RE alloy wire added is 1.1 kg / t.

[0074] The energy-saving battery aluminum foil prepared according to Example 3 has a tensile strength of 265 MPa, an elongation of 12%, and a pinhole count of 3 / m. 2 The dyn value is 36 dyn, which shows that the energy-saving battery aluminum foil prepared by the present invention has high tensile strength and elongation, is not easy to break, has low pinhole count, and has a high dyn value.

[0075] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0076] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing aluminum foil for energy-saving batteries, characterized in that, Includes the following steps: Step (a) Smelting: Smelt according to the 1235 alloy, and use slag remover and refining agent for slag removal treatment. The smelting temperature is controlled at 700℃ and the furnace pouring temperature is controlled at 710℃. Step (b) Heat preservation: The temperature of the aluminum liquid is controlled at 700℃±5℃. A modification treatment is added to the heat preservation furnace. The modification treatment is to add aluminum-strontium alloy to the heat preservation furnace and stir it with electromagnetic stirring. Every 30 minutes, it is refined with a refining agent and then the slag is removed. Step (c) Hydrogen removal: Argon gas is used as the hydrogen removal medium in the degassing box for online hydrogen removal. At the same time, Al-Ti-B-RE alloy wire is added to the degassing box, and the temperature of the aluminum liquid is controlled at 685℃±3℃. Step (d) Casting and rolling: Casting and rolling are carried out in the casting and rolling mill. The temperature of the front box is controlled at 682±2℃, the casting and rolling zone is 18-32mm, the casting and rolling speed is 1600-1800mm / min, and the thickness of the cast and rolled plate is 4.3-5.2mm. Step (e) Cold rolling: The cast-rolled plate is cold rolled at a speed of 650-720 m / min; Step (f) Heat treatment: Cold rolled to a thickness of 1.0 mm and then heat treated. The heat treatment process is as follows: first, treat at 360℃ for 8 hours, and then treat at 340℃ for 12 hours. Step (g) Cold rolling to finished product: Cold roll the cast-rolled plate to a finished size of 0.12-0.18 mm; Step (h) Corona treatment: The aluminum foil surface is corona treated with a corona equipment and kept at 42-43℃ for 8-10 hours in a closed environment to obtain energy-saving battery aluminum foil. The slagging agent in step (a) comprises the following substances in parts by weight: 40-43 parts silicon dioxide, 20-25 parts aluminum chloride, Potassium chloride 15-18 parts, sodium chloride 5-8 parts, calcium fluoride 1-3 parts, iron oxide 5-6 parts, potassium nitrate 1 part; The refining agent in step (a) comprises the following substances in parts by weight: 40-50 parts chloride auxiliaries, 15-20 parts potassium fluoroaluminate. 10-12 parts light carbonate, 1-2 parts charcoal powder, 3-5 parts hexachloroethane, 10-12 parts sodium sulfate, and 5-8 parts potassium chloride; In step (b), the refining agent is refined using liquid carbon tetrachloride, and the mass ratio of the refining agent to the aluminum alloy melt is 1:8000.

2. The method for preparing energy-saving battery aluminum foil according to claim 1, characterized in that: The mass ratio of the slag remover to the molten aluminum alloy is 1-2:3000.

3. The method for preparing energy-saving battery aluminum foil according to claim 1, characterized in that: The mass ratio of the refining agent to the aluminum alloy melt is 1:2000.

4. The method for preparing energy-saving battery aluminum foil according to claim 1, characterized in that: In step (b), the strontium content is controlled at 0.4-0.8%.

5. The method for preparing energy-saving battery aluminum foil according to claim 1, characterized in that: In step (c), the amount of Al-Ti-B-RE alloy wire added is 0.8 kg / t to 1.2 kg / t.

6. An energy-saving battery aluminum foil, characterized in that, The aluminum foil for energy-saving batteries is prepared according to any one of claims 1-5.

7. The energy-saving battery aluminum foil according to claim 6, characterized in that: The energy-saving battery aluminum foil has a tensile strength ≥256MPa, an elongation ≥8%, and a pinhole count ≤3 / m. 2 The dyn value is ≥34dyn.

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