A cold rolling process for a current collector substrate and a preparation method thereof

Abstract

The present application provides a cold rolling process for a current collector substrate and a preparation method thereof, belonging to the field of battery manufacturing. The cold rolling process includes at least three passes. Among them, after the second pass is completed, the first annealing is carried out, and after the third pass is completed, the second annealing is carried out. This cold rolling process can reduce the hardness of the current collector substrate to a certain extent, thereby effectively improving the problems of easy slippage of the coater, unstable surface density, and powder falling off of the electrode sheet.

Description

Technical Field

[0001] The present application relates to the field of battery manufacturing, and more particularly, to a cold rolling process for a current collector substrate and a preparation method thereof. Background Art

[0002] In the prior art, the preparation process of the current collector substrate usually involves a cold rolling process. However, the current collector substrate prepared by the current cold rolling process has a high hardness, and during the battery coating process, problems such as easy slippage of the coater, unstable surface density, and powder falling off the electrode sheet occur. Summary of the Invention

[0003] The purpose of the present application is to provide a cold rolling process for a current collector substrate and a preparation method thereof, which can reduce the hardness of the current collector substrate to a certain extent, thereby effectively improving the problems of easy slippage of the coater, unstable surface density, and powder falling off the electrode sheet.

[0004] The embodiments of the present application are implemented as follows:

[0005] In a first aspect, an embodiment of the present application provides a cold rolling process for a current collector substrate. The cold rolling process includes at least three passes. Among them, after the second pass is completed, the first annealing is carried out, and after the third pass is completed, the second annealing is carried out.

[0006] In the above technical solution, the first annealing is carried out after the second pass is completed, and the second annealing is carried out after the third pass is completed. Compared with other forms of annealing processes, it can effectively reduce the hardness of the current collector substrate, thereby effectively avoiding problems such as coater slippage, unstable surface density, and powder falling off the electrode sheet during the battery coating process.

[0007] In some alternative embodiments, by weight percentage, the raw materials of the current collector substrate processed by the cold rolling process include Cr: 12.3 - 14.3 wt%, Ni: 6.3 - 7.1 wt%, B: 2.5 - 2.8 wt%, Mn: 1 - 1.4 wt%, Mg: 0.3 - 0.6 wt%, Zn: 0.3 - 0.6 wt%, V: 0.3 - 0.6 wt%, and the balance is Fe.

[0008] In the above technical solution, the raw materials of the current collector substrate adopt appropriate components, and compared with using other raw material components, a current collector substrate with a more suitable hardness can be prepared.

[0009] In some alternative embodiments, in the step of the first annealing, it includes sequentially performing a first heating treatment and a first cooling treatment. During the first heating treatment, the treatment temperature is 1100 - 1200 °C, and the treatment time is 6 - 8 h.

[0010] In the above technical solution, during the first heat treatment, the treatment temperature is limited to the range of 1100 - 1200 °C, and the treatment time is limited to the range of 6 - 8 h, which can enable the first annealing to be carried out at an appropriate temperature and duration, thereby more effectively reducing the hardness of the current collector substrate.

[0011] In some alternative embodiments, during the first cooling treatment, it includes sequentially performing the first cooling, the first heat preservation, and the second cooling;

[0012] Optionally, during the first heat preservation, the treatment temperature is 600 - 700 °C, and the treatment time is 2 - 3 h.

[0013] In the above technical solution, performing the first heat preservation during the first cooling process can increase the plasticity and wear resistance of the material; further, during the first heat preservation, the treatment temperature is limited to the range of 600 - 700 °C, and the treatment time is limited to the range of 2 - 3 h, which can enable the first heat preservation to be carried out at an appropriate temperature and duration, thereby further enhancing the plasticity and wear resistance of the material.

[0014] In some alternative embodiments, in the step of the second annealing, the second heat treatment and the second cooling treatment are sequentially performed. During the second heat treatment, the treatment temperature is 1000 - 1100 °C, and the treatment time is 6 - 8 h.

[0015] In the above technical solution, during the second heat treatment, the treatment temperature is limited to the range of 1000 - 1100 °C, and the treatment time is limited to the range of 6 - 8 h, which can enable the second heat treatment to be carried out at an appropriate temperature and duration, thereby further reducing the hardness of the current collector substrate.

[0016] In some alternative embodiments, during the second cooling treatment, it includes sequentially performing the third cooling, the second heat preservation, and the fourth cooling;

[0017] Optionally, during the second heat preservation, the treatment temperature is 500 - 600 °C, and the treatment time is 3 - 5 h.

[0018] In the above technical solution, performing the second heat preservation during the second cooling process can further improve the plasticity and wear resistance of the material; further, during the second heat preservation, the treatment temperature is limited to the range of 500 - 600 °C, and the treatment time is limited to the range of 3 - 5 h, which can enable the second heat preservation to be carried out at an appropriate temperature and duration, thereby more effectively enhancing the plasticity and wear resistance of the material.

[0019] In a second aspect, an embodiment of the present application provides a method for preparing a current collector substrate, which includes successively melting, casting and rolling, cold rolling, and foil rolling the raw materials of the current collector substrate. Among them, the cold rolling step is carried out using the cold rolling process of the current collector substrate provided in the embodiment of the first aspect.

[0020] In the above technical solution, the raw materials of the current collector substrate are processed successively using the above steps, and the cold rolling step is carried out using the cold rolling process of the current collector substrate provided in the embodiment of the first aspect, so that a current collector substrate with lower hardness can be prepared, thereby effectively avoiding problems such as slippage of the coater, unstable areal density, and powder falling off the electrode sheet during the battery coating process.

[0021] In some optional embodiments, in the melting step, it further includes allowing the melt to stand still;

[0022] Optionally, during the standing process, the treatment time is 2 to 3 hours.

[0023] In the above technical solution, allowing the melt to stand still in the melting step (molecules move freely at high temperatures) can make the various elements in the raw materials of the current collector substrate mix more evenly; further, during the standing process, limiting the treatment time within the range of 2 to 3 hours can make the various elements in the raw materials of the current collector substrate mix even more evenly.

[0024] In some optional embodiments, after the casting and rolling step and before the cold rolling step, it further includes degreasing the cast and rolled body.

[0025] In the above technical solution, degreasing the cast and rolled body after the casting and rolling step and before the cold rolling step can remove the lubricating grease attached to the cast and rolled body, thereby ensuring the surface cleanliness of the cast and rolled body, and further avoiding contamination of the cast and rolled body during annealing.

[0026] In some optional embodiments, after the foil rolling step is completed, it further includes corona treating the foil rolled body.

[0027] In the above technical solution, corona treating the foil rolled body after the foil rolling step is completed can increase the surface roughness of the foil rolled body. At the same time, it can also remove water vapor, oil stains, etc. on the surface of the foil rolled body, thereby ensuring the surface cleanliness of the foil rolled body. Description of the Drawings

[0028] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0029] Figure 1 It is a process flow diagram of a preparation method of a current collector substrate provided by an embodiment of the present application. Specific embodiments

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. For those not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For the reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0031] It should be noted that in the description of the present application, unless otherwise specified, the range of "numerical value a to numerical value b" includes the two end values "a" and "b", and the "measurement unit" in "numerical value a to numerical value b + measurement unit" represents the "measurement unit" of both "numerical value a" and "numerical value b".

[0032] In the prior art, the cold rolling process involves an annealing step (continuous cold rolling causes an increase in the hardness and a decrease in the toughness of the substrate, so annealing of the substrate is required). However, in the existing cold rolling process, annealing is generally carried out after the first pass (after the first pass, the thickness of the current collector substrate is too thick, and the effect of annealing is not obvious) or after the entire cold rolling process (after the cold rolling process is completed, the current collector substrate is basically shaped, and the effect of annealing is also not obvious), resulting in a relatively high hardness of the current collector substrate, which makes it easy to occur problems such as the coating machine slipping, the surface density being unstable, and the electrode sheet shedding powder during the battery coating process.

[0033] The inventors have found through research that by adjusting the annealing process, the softening effect of the annealing process on the current collector substrate can be made more obvious, thereby effectively reducing the hardness of the current collector substrate, and further effectively improving the problems such as the coating machine slipping, the surface density being unstable, and the electrode sheet shedding powder that are likely to occur.

[0034] The cold rolling process of a current collector substrate and its preparation method according to an embodiment of the present application will be specifically described below.

[0035] In a first aspect, an embodiment of the present application provides a cold rolling process for a current collector substrate. The cold rolling process includes at least three passes. Among them, after the second pass is completed, the first annealing is carried out, and after the third pass is completed, the second annealing is carried out.

[0036] In this application, the first annealing is carried out after the second pass, and the second annealing is carried out after the third pass. Compared with other forms of annealing processes, it can effectively reduce the hardness of the current collector substrate, thus effectively avoiding problems such as slippage of the coater, unstable surface density, and powder shedding of the electrode during the battery coating process.

[0037] It should be noted that the number of cold rolling passes in the cold rolling step is not specifically limited and can be adjusted according to the actual effect of cold rolling.

[0038] It can be understood that in the cold rolling step, the degree of thickness change of the substrate will also affect the hardness, toughness, etc. of the substrate.

[0039] As an example, taking the cold rolling step of six passes as an example, cold rolling a substrate with a thickness of 6 mm to 0.3 mm can adopt the following steps:

[0040] The first pass presses from 6 mm to 4 mm, the second pass presses from 4 mm to 3 mm, the third pass presses from 3 mm to 1.5 mm, the fourth pass presses from 1.5 mm to 0.6 mm, the fifth pass presses from 0.6 mm to 0.4 mm, and the sixth pass presses from 0.4 mm to 0.3 mm.

[0041] It should be noted that considering the different cold rolling requirements of each pass, the model of the rolling mill for each pass can be adjusted.

[0042] As an example, a two-high rolling mill is used in the first pass, four-high rolling mills are used in the second and third passes, an eight-high rolling mill is used in the fourth pass, and a twenty-high rolling mill is used in the fifth and sixth passes.

[0043] In this embodiment, a two-high rolling mill is used in the first pass because the requirement for cold pressing is relatively low in the early stage of cold rolling, and the two-high rolling mill has the advantage of fast speed and can improve the cold rolling efficiency; as the number of passes increases, the number of rolls of the rolling mill used gradually increases because as the number of cold rolling passes increases, the thickness of the substrate becomes thinner and thinner, and the accuracy requirement for the rolling mill is also higher and higher.

[0044] It should be noted that annealing is not limited to only after the second pass and the third pass, and can also be carried out after the fourth pass and subsequent passes.

[0045] It can be understood that the hardness of the current collector substrate is not only related to the preparation process but also related to the raw material composition of the current collector substrate.

[0046] As an example, by weight percentage, the raw materials of the current collector substrate treated by the cold rolling process include Cr: 12.3 - 14.3 wt%, Ni: 6.3 - 7.1 wt%, B: 2.5 - 2.8 wt%, Mn: 1 - 1.4 wt%, Mg: 0.3 - 0.6 wt%, Zn: 0.3 - 0.6 wt%, V: 0.3 - 0.6 wt%, and the balance Fe.

[0047] In this embodiment, the raw materials of the current collector substrate adopt appropriate components. Compared with using other raw material components, a current collector substrate with more appropriate hardness can be prepared.

[0048] As an example, in the step of the first annealing, it includes sequentially performing the first heating treatment and the first cooling treatment. During the first heating treatment, the treatment temperature is 1100 - 1200 °C. For example, but not limited to, the treatment temperature can be any point value among 1100 °C, 1110 °C, 1120 °C, 1130 °C, 1140 °C, 1150 °C, 1160 °C, 1170 °C, 1180 °C, 1190 °C, and 1200 °C, or the range value between any two of them; the treatment time is 6 - 8 h. For example, but not limited to, the treatment time can be any point value among 6 h, 6.5 h, 7 h, 7.5 h, and 8 h, or the range value between any two of them.

[0049] In this embodiment, during the first heating treatment, the treatment temperature is limited to the range of 1100 - 1200 °C, and the treatment time is limited to the range of 6 - 8 h, which can enable the first annealing to be carried out at an appropriate temperature and duration, thereby more effectively reducing the hardness of the current collector substrate.

[0050] It should be noted that considering the stability of the physical and chemical properties of the substrate, the entire first annealing is carried out in a nitrogen atmosphere.

[0051] It can be understood that during the first heating treatment, the heating rate will also affect the physical and chemical properties of the substrate.

[0052] As an example, during the first heating treatment, the time from room temperature to the treatment temperature is 4 - 6 h. For example, but not limited to, the time can be any point value among 4 h, 5 h, and 6 h, or the range value between any two of them.

[0053] As an example, during the first cooling treatment, it includes sequentially performing the first cooling, the first heat preservation, and the second cooling;

[0054] Optionally, during the first heat preservation process, the treatment temperature is 600 - 700 °C, for example but not limited to any one point value among 600 °C, 610 °C, 620 °C, 630 °C, 640 °C, 650 °C, 660 °C, 670 °C, 680 °C, 690 °C and 700 °C or the range value between any two of them; the treatment time is 2 - 3 h, for example but not limited to any one point value among 2 h, 2.5 h and 3 h or the range value between any two of them.

[0055] In this embodiment, the first heat preservation is carried out during the first cooling process, which can increase the plasticity and wear resistance of the material; further, during the first heat preservation process, the treatment temperature is limited to the range of 600 - 700 °C, and the treatment time is limited to the range of 2 - 3 h, which can enable the first heat preservation to be carried out at an appropriate temperature and duration, thereby further enhancing the plasticity and wear resistance of the material.

[0056] It can be understood that during the first cooling and the second cooling processes, the cooling rate will also affect the physical and chemical properties of the substrate.

[0057] As an example, during the first cooling and the second cooling processes, the cooling time is 2 - 4 h, for example but not limited to any one point value among 2 h, 2.5 h, 3 h, 3.5 h and 4 h or the range value between any two of them.

[0058] It should be noted that in order to avoid affecting the physical and chemical properties of the substrate during the cooling process, the cooling method can be adjusted.

[0059] As an example, both the first cooling and the second cooling adopt vacuum cooling.

[0060] As an example, in the step of the second annealing, the second heating treatment and the second cooling treatment are carried out in sequence. During the second heating treatment, the treatment temperature is 1000 - 1100 °C, for example but not limited to any one point value among 1000 °C, 1010 °C, 1020 °C, 1030 °C, 1040 °C, 1050 °C, 1060 °C, 1070 °C, 1080 °C, 1090 °C and 1100 °C or the range value between any two of them; the treatment time is 6 - 8 h, for example but not limited to any one point value among 6 h, 6.5 h, 7 h, 7.5 h and 8 h or the range value between any two of them.

[0061] In this embodiment, during the second heating treatment, the treatment temperature is limited to the range of 1000 - 1100 °C, and the treatment time is limited to the range of 6 - 8 h, which can enable the second heating treatment to be carried out at an appropriate temperature and duration, thereby further reducing the hardness of the current collector substrate.

[0062] It should be noted that the processing temperature in the second annealing step is slightly lower than that in the first annealing step because as the number of cold rolling passes increases, the thickness of the substrate gradually thins, making the substrate more sensitive to temperature. A slightly lower temperature is used to avoid damage to the substrate caused by high temperature, thus achieving the purpose of protecting the substrate.

[0063] It should be noted that considering the stability of the physical and chemical properties of the substrate, the entire second annealing is carried out in a nitrogen atmosphere.

[0064] It can be understood that during the second heating process, the heating rate will also affect the physical and chemical properties of the substrate.

[0065] As an example, during the second heating process, the time taken to increase the temperature from room temperature to the processing temperature is 3 - 5 h, such as but not limited to any one of the point values 3 h, 3.5 h, 4 h, 4.5 h, and 5 h or the range values between any two of them.

[0066] As an example, during the second cooling process, it includes third cooling, second heat preservation, and fourth cooling in sequence;

[0067] Optionally, during the second heat preservation process, the processing temperature is 500 - 600 °C, such as but not limited to any one of the point values 500 °C, 510 °C, 520 °C, 530 °C, 540 °C, 550 °C, 560 °C, 570 °C, 580 °C, 590 °C, and 600 °C or the range values between any two of them; the processing time is 3 - 5 h, such as but not limited to any one of the point values 3 h, 3.5 h, 4 h, 4.5 h, and 5 h or the range values between any two of them.

[0068] In this embodiment, performing the second heat preservation during the second cooling process can further improve the plasticity and wear resistance of the material; further, by limiting the processing temperature within the range of 500 - 600 °C and the processing time within the range of 3 - 5 h during the second heat preservation process, the second heat preservation can be carried out at an appropriate temperature and duration, thereby being able to more effectively enhance the plasticity and wear resistance of the material.

[0069] It can be understood that during the third cooling and fourth cooling processes, the cooling rate will also affect the physical and chemical properties of the substrate.

[0070] As an example, during the third cooling process, the cooling time is 2 - 4 h, such as but not limited to any one of the point values 2 h, 2.5 h, 3 h, 3.5 h, and 4 h or the range values between any two of them.

[0071] As an example, during the fourth temperature drop, the temperature drop time is 2 to 3.5 h, such as but not limited to any one of the point values of 2 h, 2.5 h, 3 h, and 3.5 h or the range value between any two of them.

[0072] It should be noted that in order to avoid affecting the physical and chemical properties of the substrate during the temperature drop, the temperature drop method can be adjusted.

[0073] As an example, both the third temperature drop and the fourth temperature drop adopt vacuum temperature drop.

[0074] In a second aspect, an embodiment of the present application provides a method for preparing a current collector substrate, including successively melting, casting and rolling, cold rolling, and foil rolling the raw materials of the current collector substrate, wherein the cold rolling step is carried out by using the cold rolling process of the current collector substrate provided in the embodiment of the first aspect.

[0075] In the present application, the raw materials of the current collector substrate are processed successively by the above steps, and the cold rolling step is carried out by using the cold rolling process of the current collector substrate provided in the embodiment of the first aspect, so that a current collector substrate with lower hardness can be prepared, thereby effectively avoiding problems such as slipping of the coater, unstable surface density, and powder falling off the electrode during the battery coating process.

[0076] As an example, in the melting step, it further includes standing the melt;

[0077] Optionally, during the standing process, the treatment time is 2 to 3 h, such as but not limited to any one of the point values of 2 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h, 2.5 h, 2.6 h, 2.7 h, 2.8 h, 2.9 h, and 3 h or the range value between any two of them.

[0078] In this embodiment, standing the melt in the melting step (molecules will move freely at high temperatures) can make the various elements in the raw materials of the current collector substrate mix more evenly; further, during the standing process, limiting the treatment time within the range of 2 to 3 h can make the various elements in the raw materials of the current collector substrate mix even more evenly.

[0079] As an example, after the casting and rolling step and before the cold rolling step, it further includes degreasing the cast and rolled body.

[0080] In this embodiment, degreasing the cast and rolled body after the casting and rolling step and before the cold rolling step can remove the lubricating grease attached to the cast and rolled body, thereby ensuring the surface cleanliness of the cast and rolled body and further avoiding contamination of the cast and rolled body during annealing.

[0081] It should be noted that the specific process of degreasing treatment is not limited and can be set according to the conventional methods in this field.

[0082] As an example, during the degreasing treatment, the cleaning agent includes sodium tripolyphosphate: 9 - 12 g / L, sodium sulfate 0.8 g / L, disodium ethylenediaminetetraacetate 1.6 g / L, and a composite surfactant 3.9 g / L. The mass concentration of the cleaning agent in the cleaning solution is 3 - 4%; the cleaning speed of the cleaning unit is 75 - 85 m / min, the cleaning time is 3 - 5 min, and the temperature of the cleaning solution in the cleaning tank is 45 - 60 °C.

[0083] It should be noted that considering the compactness of the melt and the impurity content in the melt, it also includes treatments such as vacuum degassing and filtration to remove impurities from the melt before standing.

[0084] It should be noted that the specific process of the foil rolling step is not limited and can be carried out according to the conventional methods in this field.

[0085] As an example, in the foil rolling step, it includes rough rolling, intermediate rolling, and finish rolling in sequence, and each rolling mill in each foil rolling stage is equipped with a hydraulic device for automatically controlling the thickness of the foil rolling.

[0086] It should be noted that the number of passes in each foil rolling stage is not limited and can be adjusted according to the situation of the foil rolling.

[0087] As an example, the rough rolling includes two passes, the intermediate rolling includes two passes, and the finish rolling includes one pass, that is, a total of five passes.

[0088] It can be understood that in the foil rolling step, the degree of thickness change of the substrate will also affect the hardness, toughness, etc. of the substrate.

[0089] As an example, in the first pass, it is pressed from 0.3 mm to 0.1 mm, in the second pass from 0.1 mm to 0.05 mm, in the third pass from 0.05 mm to 0.03 mm, in the fourth pass from 0.03 mm to 0.02 mm, and in the fifth pass from 0.02 mm to 0.01 mm.

[0090] It should be noted that in order to increase the surface roughness of the substrate, the foil rolling process can be adjusted.

[0091] As an example, during the finish rolling, it also includes grinding the foil rolling body.

[0092] It should be noted that the grinding treatment is not specifically limited and can be carried out according to the conventional methods in this field.

[0093] As an example, downstream of the finishing equipment, three independent controlled grinders with particle sizes of 80#, 120#, and 180# are sequentially arranged, that is, grinding is carried out three times in sequence.

[0094] It can be understood that appropriate roughness also helps to avoid slipping of the coater during coating.

[0095] As an example, during the grinding process, the first grinding grinds the foil rolling body to 0.1 - 0.2 μm, the second grinding grinds the foil rolling body to 0.2 - 0.4 μm, and the third grinding grinds the foil rolling body to 0.4 - 0.6 μm.

[0096] As an example, after the foil rolling step is completed, it further includes corona treatment of the foil rolling body.

[0097] In this embodiment, corona treatment of the foil rolling body after the foil rolling step is completed can further increase the surface roughness of the foil rolling body. At the same time, it can also remove water vapor, oil stains, etc. on the surface of the foil rolling body, thereby ensuring the surface cleanliness of the foil rolling body.

[0098] It should be noted that the specific process of corona treatment is not limited and can be set according to the conventional methods in this field.

[0099] As an example, during the corona treatment process, the treatment power is 12 - 14 KW, the voltage is 10 - 15 KW, and the frequency is 16 - 18 KHZ.

[0100] It should be noted that the number of corona treatment times is not specifically limited.

[0101] It should be noted that in the preparation process of the current collector substrate, the steps not described in detail can be carried out according to the conventional methods in this field.

[0102] As an example, the preparation method of the current collector substrate can refer to Figure 1 the process flow chart in.

[0103] The features and performance of the present application will be further described in detail below in conjunction with the embodiments.

[0104] Example 1

[0105] The embodiment of the present application provides a method for preparing a current collector substrate, including the following steps:

[0106] The raw materials of the current collector substrate are melted to obtain a melt. Then, the obtained melt is successively subjected to vacuum degassing, filtration for impurity removal, and static treatment to obtain a 6-mm-thick melt. Among them, by weight percentage, the raw materials of the current collector substrate include Cr: 13 wt%, Ni: 6.8 wt%, B: 2.5 wt%, Mn: 1 wt%, Mg: 0.5 wt%, Zn: 0.5 wt%, V: 0.5 wt%, and the balance Fe. The static time is 2.5 h.

[0107] The static melt is subjected to continuous casting and rolling to obtain a continuously cast and rolled body.

[0108] A cleaning unit is used to degrease the continuously cast and rolled body. Among them, the cleaning agent includes sodium tripolyphosphate: 10 g / L, sodium sulfate 0.8 g / L, disodium ethylenediaminetetraacetate 1.6 g / L, and a composite surfactant 3.9 g / L. The mass concentration of the cleaning agent in the cleaning solution is 3%. The cleaning speed of the cleaning unit is 80 m / min, the cleaning time is 4 min, and the temperature of the cleaning solution in the cleaning tank is 54 °C.

[0109] The degreased continuously cast and rolled body is subjected to the first pass of cold rolling using a two-high rolling mill, reducing the continuously cast and rolled body from 6 mm to 4 mm. Then, the second pass of cold rolling is carried out using a four-high rolling mill, reducing the continuously cast and rolled body from 4 mm to 3 mm.

[0110] Then, the continuously cast and rolled body is successively subjected to the first heating, the first cooling, the first heat preservation, and the second cooling. Among them, the heating-up time in the first heating process is 5 h, the treatment temperature is 1150 °C, the treatment time is 7 h, the cooling-down time in the first cooling process is 3 h, the temperature in the first heat preservation process is 650 °C, the heat preservation time is 2.5 h, and the time in the second cooling process is 3 h.

[0111] Then, the third pass of cold rolling is carried out using a four-high rolling mill, reducing the continuously cast and rolled body from 3 mm to 1.5 mm.

[0112] Then, the continuously cast and rolled body is successively subjected to the second heating, the third cooling, the second heat preservation, and the fourth cooling. Among them, the heating-up time in the second heating process is 4 h, the treatment temperature is 1050 °C, the treatment time is 7 h, the cooling-down time in the third cooling process is 3 h, the temperature in the second heat preservation process is 550 °C, the heat preservation time is 4 h, and the time in the fourth cooling process is 3 h.

[0113] Then, the fourth pass of cold rolling is carried out on the continuously cast and rolled body using an eight-high rolling mill, reducing the continuously cast and rolled body from 1.5 mm to 0.6 mm. Then, the fifth and sixth passes of cold rolling are successively carried out using a twenty-high rolling mill, reducing the continuously cast and rolled body from 0.6 mm to 0.4 mm and then from 0.4 mm to 0.3 mm, respectively, to obtain a cold-rolled body.

[0114] Then, the cold-rolled body is successively subjected to rough rolling, intermediate rolling, and finish rolling to obtain a foil-rolled body. Among them, the rough rolling includes two passes, pressing the cold-rolled body from 0.3 mm to 0.1 mm and then from 0.1 mm to 0.05 mm. The intermediate rolling includes two passes, pressing the cold-rolled body from 0.05 mm to 0.03 mm and then from 0.03 mm to 0.02 mm. The finish rolling includes one pass, pressing the cold-rolled body from 0.02 mm to 0.01 mm;

[0115] Then, the obtained foil-rolled body is successively polished three times. Among them, the particle sizes of the three grinders are 80#, 120#, and 180# respectively, and the roughness of the foil-rolled body is polished to 0.15 μm, 0.3 μm, and 0.5 μm respectively;

[0116] Then, the polished foil-rolled body is subjected to corona treatment twice to obtain a current collector substrate. Among them, the power of the corona treatment is 13 KW, the voltage is 12 KW, and the frequency is 17 KHZ.

[0117] Example 2

[0118] The embodiment of the present application provides a method for preparing a current collector substrate, including the following steps:

[0119] The raw materials of the current collector substrate are melted to obtain a melt. Then, the obtained melt is successively subjected to vacuum outgassing, filtration for impurity removal, and standing treatment to obtain a 6-mm-thick melt. Among them, calculated by weight percentage, the raw materials of the current collector substrate include Cr: 13 wt%, Ni: 6.8 wt%, B: 2.5 wt%, Mn: 1 wt%, Mg: 0.5 wt%, Zn: 0.5 wt%, V: 0.5 wt%, and the balance is Fe. The standing time is 2 h;

[0120] The standing melt is subjected to casting and rolling to obtain a cast-rolled body;

[0121] The cast-rolled body is degreased by a cleaning unit. Among them, the cleaning agent includes sodium tripolyphosphate: 10 g / L, sodium sulfate 0.8 g / L, disodium ethylenediaminetetraacetate 1.6 g / L, and a composite surfactant 3.9 g / L. The mass concentration of the cleaning agent in the cleaning solution is 3%; the cleaning speed of the cleaning unit is 75 m / min, the cleaning time is 3 min, and the temperature of the cleaning solution in the cleaning tank is 45 °C;

[0122] The degreased cast-rolled body is subjected to the first pass of cold rolling by a two-high rolling mill, pressing the cast-rolled body from 6 mm to 4 mm; then, the second pass of cold rolling is carried out by a four-high rolling mill, pressing the cast-rolled body from 4 mm to 3 mm;

[0123] Then, the cast-rolled body is successively subjected to the first heating, the first cooling, the first heat preservation, and the second cooling. Among them, the heating-up time during the first heating process is 6 h, the treatment temperature is 1100 °C, and the treatment time is 8 h; the cooling time during the first cooling process is 2 h; the temperature during the first heat preservation process is 700 °C, and the heat preservation time is 2 h; the time during the second cooling process is 2 h.

[0124] Then, the third-pass cold rolling is carried out by using a four-high rolling mill, and the cast-rolled body is pressed from 3 mm to 1.5 mm.

[0125] Then, the cast-rolled body is successively subjected to the second heating, the third cooling, the second heat preservation, and the fourth cooling. Among them, the heating-up time during the second heating process is 3 h, the treatment temperature is 1050 °C, and the treatment time is 6 h; the cooling time during the third cooling process is 2 h; the temperature during the second heat preservation process is 500 °C, and the heat preservation time is 3 h; the time during the fourth cooling process is 2 h.

[0126] Then, the fourth-pass cold rolling of the cast-rolled body is carried out by using an eight-high rolling mill, and the cast-rolled body is pressed from 1.5 mm to 0.6 mm; then, the fifth and sixth passes of cold rolling are successively carried out by using a twenty-high rolling mill, and the cast-rolled body is respectively pressed from 0.6 mm to 0.4 mm and then from 0.4 mm to 0.3 mm to obtain a cold-rolled body.

[0127] Then, the cold-rolled body is successively subjected to rough rolling, intermediate rolling, and finish rolling to obtain a foil-rolled body. Among them, the rough rolling includes two passes, and the cold-rolled body is pressed from 0.3 mm to 0.1 mm and then from 0.1 mm to 0.05 mm; the intermediate rolling includes two passes, and the cold-rolled body is pressed from 0.05 mm to 0.03 mm and then from 0.03 mm to 0.02 mm; the finish rolling includes one pass, and the cold-rolled body is pressed from 0.02 mm to 0.01 mm.

[0128] Then, the obtained foil-rolled body is successively polished three times. Among them, the particle sizes of the three grinders are 80#, 120#, and 180# respectively, and the roughness of the foil-rolled body is polished to 0.1 μm, 0.2 μm, and 0.4 μm respectively.

[0129] Then, the polished foil-rolled body is subjected to corona treatment twice to obtain a current collector substrate. Among them, the power of the corona treatment is 12 KW, the voltage is 10 KW, and the frequency is 16 KHZ.

[0130] Example 3

[0131] The embodiment of the present application provides a preparation method of a current collector substrate, including the following steps:

[0132] The raw materials of the current collector substrate are melted to obtain a melt. Then, the obtained melt is successively subjected to vacuum outgassing, filtration for impurity removal, and static treatment to obtain a 6-mm-thick melt. Among them, by weight percentage, the raw materials of the current collector substrate include Cr: 13 wt%, Ni: 6.8 wt%, B: 2.5 wt%, Mn: 1 wt%, Mg: 0.5 wt%, Zn: 0.5 wt%, V: 0.5 wt%, and the balance is Fe. The static time is 3 h.

[0133] The static melt is subjected to casting and rolling to obtain a cast-rolled body.

[0134] A cleaning unit is used to degrease the cast-rolled body. Among them, the cleaning agent includes sodium tripolyphosphate: 10 g / L, sodium sulfate 0.8 g / L, disodium ethylenediaminetetraacetate 1.6 g / L, and a composite surfactant 3.9 g / L. The mass concentration of the cleaning agent in the cleaning solution is 4%. The cleaning speed of the cleaning unit is 85 m / min, the cleaning time is 5 min, and the temperature of the cleaning solution in the cleaning tank is 60 °C.

[0135] A two-high rolling mill is used to perform the first pass of cold rolling on the degreased cast-rolled body, reducing the thickness of the cast-rolled body from 6 mm to 4 mm. Then, a four-high rolling mill is used to perform the second pass of cold rolling, reducing the thickness of the cast-rolled body from 4 mm to 3 mm.

[0136] Then, the cast-rolled body is successively subjected to the first heating, the first cooling, the first heat preservation, and the second cooling. Among them, the heating-up time during the first heating process is 8 h, the treatment temperature is 1200 °C, the treatment time is 8 h, the cooling time during the first cooling process is 4 h, the temperature during the first heat preservation process is 600 °C, the heat preservation time is 3 h, and the time during the second cooling process is 4 h.

[0137] Then, a four-high rolling mill is used to perform the third pass of cold rolling, reducing the thickness of the cast-rolled body from 3 mm to 1.5 mm.

[0138] Then, the cast-rolled body is successively subjected to the second heating, the third cooling, the second heat preservation, and the fourth cooling. Among them, the heating-up time during the second heating process is 5 h, the treatment temperature is 1100 °C, the treatment time is 8 h, the cooling time during the third cooling process is 4 h, the temperature during the second heat preservation process is 600 °C, the heat preservation time is 5 h, and the time during the fourth cooling process is 3.5 h.

[0139] Then, an eight-high rolling mill is used to perform the fourth pass of cold rolling on the cast-rolled body, reducing the thickness of the cast-rolled body from 1.5 mm to 0.6 mm. Then, a twenty-high rolling mill is used to perform the fifth and sixth passes of cold rolling successively, reducing the thickness of the cast-rolled body from 0.6 mm to 0.4 mm and then from 0.4 mm to 0.3 mm, respectively, to obtain a cold-rolled body.

[0140] Then, the cold-rolled body is successively subjected to primary rolling, intermediate rolling, and finish rolling to obtain a foil-rolled body. Among them, the primary rolling includes two passes, pressing the cold-rolled body from 0.3 mm to 0.1 mm and then from 0.1 mm to 0.05 mm. The intermediate rolling includes two passes, pressing the cold-rolled body from 0.05 mm to 0.03 mm and then from 0.03 mm to 0.02 mm. The finish rolling includes one pass, pressing the cold-rolled body from 0.02 mm to 0.01 mm;

[0141] Then, the obtained foil-rolled body is successively polished three times. Among them, the particle sizes of the three grinders are 80#, 120#, and 180# respectively, and the roughness of the foil-rolled body is polished to 0.2 μm, 0.4 μm, and 0.6 μm respectively;

[0142] Then, the polished foil-rolled body is subjected to corona treatment twice to obtain a current collector substrate. Among them, the power of the corona treatment is 14 KW, the voltage is 15 KW, and the frequency is 18 KHZ.

[0143] Comparative Example 1

[0144] The embodiment of the present application provides a method for preparing a current collector substrate, and the difference from Embodiment 1 is only that:

[0145] The first annealing is carried out after the first pass of cold rolling, and the second annealing is carried out after the third pass of cold rolling.

[0146] Comparative Example 2

[0147] The embodiment of the present application provides a method for preparing a current collector substrate, and the difference from Embodiment 1 is only that:

[0148] The first annealing is carried out only after the second pass of cold rolling.

[0149] Comparative Example 3

[0150] The embodiment of the present application provides a method for preparing a current collector substrate, and the difference from Embodiment 1 is only that:

[0151] The second annealing is carried out only after the third pass of cold rolling.

[0152] Test Example 1

[0153] Hardness test of the current collector substrate

[0154] Test method: The current collector substrates are prepared respectively according to the preparation methods of Embodiment 1 and Comparative Examples 1-3. Then, the obtained current collector substrates are numbered respectively, and then the hardness of each current collector substrate is tested.

[0155] Table 1 Hardness test results of the current collector substrate

[0156] Specimen Name Vickers Hardness (HV) Example 1 142 Example 2 141 Example 3 143 Comparative Example 1 146 Comparative Example 2 151 Comparative Example 3 153

[0157] Referring to Table 1, by comparing Examples 1 to 3 with Comparative Example 1, it can be seen that the first and second annealing processes are carried out after the completion of the second and third passes respectively. Compared with carrying out the first and second annealing processes after the completion of the first and third passes respectively, the hardness of the current collector substrate obtained is lower, indicating that carrying out the first and second annealing processes after the completion of the second and third passes can make the annealing process play a greater role.

[0158] By comparing Example 1 with Comparative Example 2 and Example 1 with Comparative Example 3 respectively, it can be seen that when only one annealing process is carried out after the completion of the second or third pass, the hardness of the current collector substrate is relatively high, indicating that carrying out the first and second annealing processes after the completion of the second and third passes respectively can make the annealing process play a greater role.

[0159] The embodiments described above are some, but not all, of the embodiments of the present application. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application claimed, but merely represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts fall within the scope of protection of the present application.

Claims

1. A cold rolling process for a current collector substrate, characterized in that, The cold rolling process has six passes. After the second pass is completed, the first annealing is carried out. After the third pass is completed, the second annealing is carried out; Among them, by weight percentage, the raw materials of the current collector substrate processed by the cold rolling process include Cr: 12.3 - 14.3 wt%, Ni: 6.3 - 7.1 wt%, B: 2.5 - 2.8 wt%, Mn: 1 - 1.4 wt%, Mg: 0.3 - 0.6 wt%, Zn: 0.3 - 0.6 wt%, V: 0.3 - 0.6 wt%, and the balance is Fe.

2. The cold rolling process of the current collector substrate according to claim 1, characterized in that, In the step of the first annealing, it includes sequentially performing the first heating treatment and the first cooling treatment. During the first heating treatment, the treatment temperature is 1100 - 1200 °C, and the treatment time is 6 - 8 h.

3. The cold rolling process of the current collector substrate according to claim 2, characterized in that, During the first cooling treatment, it includes sequentially performing the first cooling, the first heat preservation, and the second cooling.

4. The cold rolling process of the current collector substrate according to claim 3, characterized in that, During the first heat preservation, the treatment temperature is 600 - 700 °C, and the treatment time is 2 - 3 h.

5. The cold rolling process of the current collector substrate according to any one of claims 1 to 4, characterized in that In the step of the second annealing, it includes sequentially performing the second heating treatment and the second cooling treatment. During the second heating treatment, the treatment temperature is 1000 - 1100 °C, and the treatment time is 6 - 8 h.

6. The cold rolling process of the current collector substrate according to claim 5, characterized in that, During the second cooling treatment, it includes sequentially performing the third cooling, the second heat preservation, and the fourth cooling.

7. The cold rolling process of the current collector substrate according to claim 6, characterized in that, During the second heat preservation, the treatment temperature is 500 - 600 °C, and the treatment time is 3 - 5 h.

8. A method for preparing a current collector substrate, characterized in that, It includes sequentially melting, continuous casting and rolling, cold rolling, and foil rolling the raw materials of the current collector substrate. Among them, the step of cold rolling is carried out by using the cold rolling process of the current collector substrate as described in any one of claims 1 - 7.

9. The method for preparing a current collector substrate according to claim 8, wherein In the step of melting, it also includes standing the melt.

10. The method for preparing the current collector substrate according to claim 9, wherein During the standing process, the treatment time is 2 - 3 h.

11. The method for preparing a current collector substrate according to claim 8, characterized in that, After the step of continuous casting and rolling is carried out and before the step of cold rolling is carried out, it also includes degreasing the continuously cast and rolled body.

12. The preparation method of the current collector substrate according to any one of claims 8 to 11, characterized in that, After the step of foil rolling is completed, it also includes corona treatment of the foil rolled body.

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