Aluminum material, aluminum foil and preparation method and application thereof

Abstract

The embodiment of the invention provides an aluminum material, an aluminum foil and a preparation method and application of the aluminum material and the aluminum foil, the aluminum material comprises one or more of Zn, Mg and Zr with the total mass percentage being 0.03%-0.1% and Al with the mass percentage being larger than or equal to 99.6%, the aluminum material further comprises impurity elements, and the mass percentage of the single impurity element is smaller than 0.015%. By adopting the aluminum material meeting the above characteristics, the aluminum foil can have good conductivity, tensile strength and process yield at the same time, the internal resistance of the aluminum foil is reduced, and the needling effect of the aluminum foil is improved.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and particularly to an aluminum material, aluminum foil, and their preparation methods and applications. Background Art

[0002] In the design and manufacture of lithium-ion batteries, as a positive current collector, the physical properties of aluminum foil are particularly important, especially its tensile strength and electrical conductivity.

[0003] To improve the tensile strength of aluminum foil, other alloying elements are usually added to the aluminum material, such as iron, silicon, and copper, etc., so as to improve the tensile strength of the aluminum foil made of the aluminum material.

[0004] However, adding alloying elements will reduce the electrical conductivity of the aluminum foil to a certain extent. Therefore, it is impossible to make the aluminum foil have good electrical conductivity, tensile strength, process yield at the same time, which affects the internal resistance and puncture effect of the aluminum foil. Summary of the Invention

[0005] The embodiments of this application provide an aluminum material, aluminum foil, and their preparation methods and applications, so as to achieve good electrical conductivity, tensile strength, process yield, internal resistance, and puncture effect at the same time.

[0006] In a first aspect, the embodiments of this application provide an aluminum material, which includes:

[0007] One or more of Zn, Mg, and Zr with a total mass percentage of 0.03% - 0.1%, and Al with a mass percentage ≥ 99.6%;

[0008] The composition of the aluminum material further includes impurity elements, and the mass percentage of the impurity elements < 0.015%.

[0009] In a possible implementation manner, the aluminum material further includes:

[0010] Fe with a mass percentage ≤ 0.3%;

[0011] And / or, Si with a mass percentage ≤ 0.1%;

[0012] And / or, Cu with a mass percentage ≤ 0.1%;

[0013] And / or, Ti with a mass percentage ≤ 0.05%.

[0014] In a possible implementation manner, the aluminum material may further include:

[0015] Fe with a mass percentage ≤ 0.15%;

[0016] And / or, Si with a mass percentage ≤ 0.04%;

[0017] And / or, Cu with a mass percentage ≤ 0.05%;

[0018] And / or, Ti with a mass percentage ≤ 0.04%.

[0019] In a second aspect, an embodiment of the present application provides an aluminum foil, including the aluminum material described in the first aspect.

[0020] In a possible implementation manner, the thickness of the aluminum foil is 10 - 20 micrometers.

[0021] In a possible implementation manner, the tensile strength of the aluminum foil is greater than or equal to 230 Mpa, the elongation rate is greater than or equal to 3.0%, and the conductivity is greater than or equal to 36 * 10 6 S / m.

[0022] In a third aspect, an embodiment of the present application provides a method for preparing an aluminum foil, including the following steps:

[0023] S1. Melting the aluminum material of the components in the first aspect;

[0024] S2. Casting;

[0025] S3. Rolling and annealing.

[0026] In a fourth aspect, an embodiment of the present application provides a positive electrode current collector, and the positive electrode current collector includes the aluminum foil in the first aspect or the aluminum foil prepared by the preparation method in the second aspect.

[0027] In a fifth aspect, an embodiment of the present application provides a positive electrode plate, including a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector, and the positive electrode current collector adopts the positive electrode current collector in the third aspect.

[0028] In a sixth aspect, a battery includes the positive electrode plate in the fourth aspect.

[0029] In a seventh aspect, an electrical device includes the battery in the fifth aspect.

[0030] The aluminum material, aluminum foil and their preparation methods and applications provided by the embodiments of the present application. The aluminum material contains one or more of Zn, Mg, and Zr with a total mass percentage of 0.03% - 0.1%, and Al with a mass percentage ≥ 99.6%. The composition of the aluminum material also includes impurity elements, and the mass percentage of a single impurity element < 0.015%. By using the aluminum material that meets the above characteristics, the aluminum foil can simultaneously have good conductivity, tensile strength and process yield, reduce the internal resistance of the aluminum foil, and improve the needle punching effect of the aluminum foil. Detailed implementation manners

[0031] Here, exemplary embodiments will be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0032] Among them, the contents described in the present application are all mass percentages.

[0033] According to the research of the inventors, for the existing aluminum foil used as the positive electrode current collector, alloying elements are added to the aluminum material to improve the tensile strength of the aluminum foil. For example, elements such as iron, silicon, and copper are added, which will lead to a decrease in the purity of aluminum in the aluminum material. For example, the content of aluminum is reduced to 99.0%-99.35%. The reduction in the purity of aluminum in turn leads to a decrease in the conductivity of the prepared aluminum foil, thereby affecting the internal resistance of the lithium-ion battery and reducing the energy conversion efficiency of the battery containing the aluminum foil. Therefore, after the addition of the existing alloying elements, a contradiction between tensile strength and conductivity is formed, and it is difficult to find an ideal balance in the design of high-performance batteries.

[0034] In addition, while the existing aluminum foil uses alloying elements to improve the tensile strength, it often does not have a good needle penetration rate, thereby increasing the possibility of short circuit and safety accidents in the battery under extreme conditions.

[0035] Based on the above technical problems, the inventive concept of the present application lies in: by adjusting the types and contents of alloying elements in the aluminum material, preparing aluminum foil with good tensile strength, conductivity, and needle penetration rate, aiming to solve the above technical problems of the prior art.

[0036] An embodiment of the present invention provides an aluminum material, including the following components:

[0037] One or more of Zn, Mg, and Zr with a total mass percentage of 0.03%-0.1%, and Al with a mass percentage ≥99.6%.

[0038] Among them, the components of the aluminum material also include impurity elements. For example, one or more of more than 20 impurity elements inherent in electrolytic aluminum ingots such as Mn, Sn, Ag, Ga, Ge, As, Gd, In, Pb, Bi, Hg, Sr, Ca, Na, S, P, V, Cr, Ni, K, B, etc., and the mass percentage of a single impurity element <0.015%.

[0039] In the embodiments of the present invention, adding alloying elements to aluminum materials helps improve the tensile strength of aluminum foils made from the aluminum materials. However, it will affect the conductivity of the aluminum foils, increase the internal resistance of the aluminum foils, and affect the process yield of the aluminum foils. Therefore, the content of the alloying elements needs to be within a certain range. In this embodiment, the content of the alloying elements in the aluminum material is 0.03%-0.1%, which helps improve the tensile capacity of the aluminum foil made from the aluminum material, while keeping the aluminum foil with a high conductivity, reducing the internal resistance of the aluminum foil, and improving the process yield of the aluminum foil.

[0040] Exemplarily, the content of the alloying elements can be 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1% or the range composed of any two of them.

[0041] The types of the alloying elements can be one or more of Zn, Mg and Zr. Zn, Mg and Zr can improve the tensile strength of the aluminum foil made from the aluminum material.

[0042] In the embodiments of the present invention, the aluminum material can also include impurity elements, which help improve the needle punching effect of the aluminum foil. And the content of a single impurity element <0.015%, so that the aluminum foil made from the aluminum material has a high conductivity.

[0043] Exemplarily, the content of a single impurity element can be 0.002%, 0.004%, 0.006%, 0.008%, 0.01%, 0.012%, 0.014% or the range composed of any two of them.

[0044] Therefore, in the embodiments of the present invention, by using the aluminum material that meets the above characteristics, the aluminum foil can simultaneously have good conductivity, tensile strength and process yield, reduce the internal resistance of the aluminum foil, and improve the needle punching effect of the aluminum foil.

[0045] Optionally, the aluminum material further includes: Fe with a mass percentage ≤0.3%; and / or, Si with a mass percentage ≤0.1%; and / or, Cu with a mass percentage ≤0.1%; and / or, Ti with a mass percentage ≤0.05%.

[0046] By adding Fe element, the tensile strength can be improved, but the Fe element cannot be added in excess, otherwise the conductivity will be reduced, the internal resistance will be increased, and the needle punching risk will be increased. Therefore, the content of Fe does not exceed 0.3%. While improving the tensile strength, keep a high conductivity, reduce the internal resistance, and improve the needle punching effect.

[0047] By adding Si element, the fluidity of the aluminum material can be improved, and then the process yield can be improved. However, it also cannot be added in excess, otherwise the conductivity will be reduced. Therefore, the content of Si is not higher than 0.1%, so as to keep a high conductivity while improving the process yield.

[0048] By adding Cu element, the strength and hardness of the aluminum foil can be improved, thereby enhancing the tensile strength. When the aluminum foil is used as an electrode sheet, it also helps to form a passivation film and improve the corrosion resistance of the aluminum foil. However, if the addition of Cu element is excessive, the conductivity will be reduced, the internal resistance will be increased, and the process yield will be decreased. Therefore, the content of Cu is not higher than 0.1%, so as to maintain a high conductivity, reduce the internal resistance, and improve the needle punching effect while enhancing the tensile strength.

[0049] By adding Ti element, the tensile strength and ductility of the aluminum foil can be improved, the rolling cracks can be reduced, and the process yield can be enhanced. However, if the addition of Ti element is excessive, the conductivity will be decreased. Therefore, the content of Ti is not higher than 0.05%, so as to maintain a high conductivity while improving the tensile strength, ductility and process yield of the aluminum foil.

[0050] Exemplarily, the content of Fe can be 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3% or any combination of any two of them.

[0051] Exemplarily, the content of Si can be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1% or a range composed of any two of them.

[0052] Exemplarily, the content of Cu can be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1% or a range composed of any two of them.

[0053] Exemplarily, the content of Ti can be 0.01%, 0.02%, 0.03%, 0.04%, 0.05% or a range composed of any two of them.

[0054] In some embodiments, the aluminum material includes Fe with a mass percentage ≤ 0.15%; and / or, Si with a mass percentage ≤ 0.04%; and / or, Cu with a mass percentage ≤ 0.05%; and / or, Ti with a mass percentage ≤ 0.04%. Within this range, the tensile capacity of the aluminum foil made of the aluminum material can be further improved, the conductivity, process yield and needle punching effect can be further enhanced, and the internal resistance can be reduced.

[0055] This application also provides an aluminum foil, including the above-mentioned aluminum material.

[0056] Exemplarily, the thickness of the aluminum foil is 10 - 20 microns.

[0057] For example, when the thickness of the aluminum foil is 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, or within the range composed of any two of them, it is beneficial to reduce the battery impedance and improve the battery performance such as capacity.

[0058] Optionally, the tensile strength of the aluminum foil is greater than or equal to 230 Mpa, the elongation is greater than or equal to 3.0%, and the conductivity is greater than or equal to 36×10 6 S / m. Since this aluminum foil is made based on the above-mentioned aluminum material, it can improve the elongation and conductivity while enhancing the tensile ability.

[0059] This application also provides an aluminum foil, which is similar to the aluminum foil in the above embodiment, except that the composition is different, including the following components:

[0060] One or more of Zn, Mg, and Zr with a total mass percentage of 0.03 - 0.1%, Al with a mass percentage ≥ 99.6%, and Cu with a mass percentage ≤ 0.1%.

[0061] By adding Cu element, the strength and hardness of the aluminum foil can be improved, thereby enhancing the tensile strength. When the aluminum foil is used as an electrode sheet, it also helps in the formation of a passivation film and improves the corrosion resistance of the aluminum foil. However, if the Cu element is added in excess, it will reduce the conductivity, increase the internal resistance, and lower the process yield.

[0062] There is also an aluminum foil, which is similar to the aluminum foil in the above embodiment, except that the composition is different, including the following components:

[0063] One or more of Zn, Mg, and Zr with a total mass percentage of 0.03 - 0.1%, Al with a mass percentage ≥ 99.6%, and Ti with a mass percentage ≤ 0.05%.

[0064] By adding Ti element, the tensile strength and ductility of the aluminum foil can be improved, the rolling cracks can be reduced, and the process yield can be enhanced. However, if the Ti element is added in excess, it will reduce the conductivity.

[0065] Another aluminum foil, which is similar to the aluminum foil in the above embodiment, except that the composition is different, including the following components:

[0066] One or more of Zn, Mg, and Zr with a total mass percentage of 0.03 - 0.1%, Al with a mass percentage ≥ 99.6%, and Cu with a mass percentage ≤ 0.1% and Ti with a mass percentage ≤ 0.05%.

[0067] By adding Cu element and Ti element simultaneously, the tensile strength and process yield of the aluminum foil can be improved simultaneously.

[0068] To prepare the above-mentioned aluminum foil, the main steps are as follows:

[0069] S1. Melt the raw materials corresponding to the above components and their mass fractions.

[0070] Specifically, put these materials into a high-temperature furnace for melting, and the temperature is generally 700 - 800 °C.

[0071] S2. Casting.

[0072] Specifically, the molten aluminum alloy forms aluminum ingots through the casting process. This process can adopt the horizontal casting or vertical casting method. After casting, the aluminum ingots need to be cooled to room temperature.

[0073] S3. Rolling and annealing.

[0074] Among them, rolling can be divided into cold rolling or hot rolling, and annealing can choose crystallization annealing or stress relief annealing to make the final thickness of the aluminum foil between 10 - 20 microns.

[0075] Exemplarily, adopting the hot rolling route, after the cast aluminum ingots are cooled, they will be heated to 400 - 600 °C for homogenization annealing. The heated aluminum ingots are subjected to heavy hot rolling through a hot rolling mill to reduce their thickness. Usually, the initial thickness can be between several centimeters and more than ten centimeters. Each stage of hot rolling requires multiple rollings to gradually thin the aluminum material.

[0076] The preliminarily thinned aluminum sheet strip enters the cold rolling stage. Cold rolling is to roll the aluminum foil at room temperature. This process is usually used to further reduce the thickness of the aluminum foil until the target thickness of 10 - 20 microns is reached, and an annealing is required in the middle.

[0077] The purpose of the first annealing is to eliminate the internal stress generated during the hot rolling process and restore the ductility of the aluminum material. The annealing temperature is generally 200 - 400 °C, and the duration varies according to the thickness of the aluminum foil and the alloy composition. Annealing can not only improve the mechanical properties of the aluminum foil but also make it more uniform, laying a foundation for the subsequent cold rolling process. After annealing, the thickness of the aluminum foil will expand slightly, and this expansion phenomenon is also a normal phenomenon in this process.

[0078] During the cold rolling process, the thickness of the aluminum foil is thinned very finely, and this process can be optimized by changing parameters such as the roll diameter, rolling speed, and rolling pressure. At the same time, cold rolling will also make the surface of the aluminum foil smoother and improve the surface quality.

[0079] This embodiment also provides a positive current collector, which uses the aluminum foil in the above embodiment or the aluminum foil prepared by the preparation method in the above embodiment.

[0080] This embodiment also provides a positive electrode sheet, which includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, and the positive electrode current collector adopts the positive electrode current collector in the above embodiment.

[0081] When specifically preparing the positive electrode sheet, for example, the positive electrode active material, the conductive agent and the binder can be dispersed in an appropriate amount of N-methylpyrrolidone (NMP) solvent, and fully stirred and mixed to form a uniform positive electrode slurry; the positive electrode slurry is uniformly coated on the positive electrode current collector of the present invention, and after drying, rolling and slitting, the positive electrode sheet is obtained.

[0082] In a specific embodiment, the positive electrode active layer includes 70-99 wt% of the positive electrode active material, 0.5-15 wt% of the conductive agent, and 0.5-15 wt% of the binder according to mass percentage.

[0083] Further, it includes 80-98 wt% of the positive electrode active material, 1-10 wt% of the conductive agent, and 1-10 wt% of the binder.

[0084] Among them, the material of the positive electrode current collector can be at least one of aluminum foil and nickel foil; the conductive agent can be selected from at least one of carbon black, acetylene black, graphene, Ketjen black, and carbon fiber; the binder can be selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polymers containing ethylene oxide, polyvinylpyrrolidone, and polyurethane.

[0085] This embodiment also provides a battery, such as a lithium-ion battery.

[0086] It can be conceived that in addition to the above positive electrode sheet, the lithium-ion battery of the present invention further includes a negative electrode sheet, an electrolyte and a separator.

[0087] The present invention does not strictly limit the positive electrode active material in the positive electrode sheet, and it can be the positive electrode active material commonly used in current lithium-ion batteries.

[0088] For example, it is at least one composite oxide of lithium and at least one of cobalt, manganese, nickel and their combinations. Optionally, positive electrode materials commonly used in lithium-ion batteries such as nickel cobalt manganese oxide (NCM), nickel cobalt aluminum oxide (NCA) or lithium iron phosphate (LFP) are selected.

[0089] Specifically, it can be at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, nickel cobalt manganese ternary material, nickel cobalt aluminum ternary material, lithium iron phosphate (LFP), lithium nickel manganese oxide, and lithium-rich manganese-based material.

[0090] It should be understood that during the preparation of the positive electrode plate, a conductive agent and a binder are usually also used. The positive electrode material, conductive agent, and binder are mixed in proportion, and an appropriate amount of solvent is added to make a uniform slurry.

[0091] Exemplarily, carbon black (such as SuperP) is usually used as the conductive agent to enhance the conductivity of the electrode. Polyvinylidene fluoride (PVDF) and other synthetic resins are generally used as the binder to provide good adhesion and mechanical stability.

[0092] The mixed slurry is uniformly coated on the aluminum foil (positive electrode current collector) to form the positive electrode plate; the same method is used to coat the negative electrode slurry on the copper foil (negative electrode current collector). The single-sided coating thickness is generally controlled within 50 - 150 microns.

[0093] The coated electrode plate is placed in a drying device to remove the solvent, obtaining a dried electrode. A compaction device is used to compact the dried electrode plate to improve the density and conductivity of the electrode.

[0094] The negative electrode active material in the negative electrode plate of the present invention is not strictly limited and can be the negative electrode active materials commonly used in current lithium-ion batteries, such as at least one of graphite, artificial graphite, hard carbon, soft carbon, mesophase carbon microspheres, silicon-based negative electrode materials (mainly including silicon monoxide and silicon-carbon negative electrodes), tin-based negative electrode materials (mainly including tin and tin alloys), etc.

[0095] The choice of the electrolyte of the present invention is not strictly limited. Generally, it is a mixture of a lithium salt dissolved in an organic solvent. It can include one or more of the solvents commonly used in current lithium-ion battery electrolytes, as well as the electrolyte lithium salts commonly used in current lithium-ion electrolytes.

[0096] For example: the solvent can be ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate (FEC), dimethyl carbonate (DMC), diethyl carbonate (DEC), difluoroethylene carbonate (DFEC), dipropyl carbonate, ethyl methyl carbonate (EMC), ethyl acetate, propyl acetate, ethyl propionate, propyl propionate, sulfolane, γ-butyrolactone, etc.; the lithium salt can be selected from one or more of lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethylsulfonyl)imide (LiTFSI).

[0097] The choice of the separator material of the present invention is not strictly limited and can be the separator materials commonly used in current lithium-ion batteries, such as one of polypropylene separator (PP), polyethylene separator (PE), polypropylene / polyethylene double-layer composite film (PP / PE), polyimide electrospun separator (PI), polypropylene / polyethylene / polypropylene three-layer composite film (PP / PE / PP), cellulose non-woven separator, and separator with a ceramic coating.

[0098] When preparing a lithium-ion battery, a positive electrode sheet, a separator, and a negative electrode sheet are wound or laminated to obtain a bare battery cell, and the bare battery cell is encapsulated into a pre-stamped aluminum-plastic film bag. After the encapsulated battery is dried at 85 °C to remove moisture, an electrolyte is injected into the dried battery to ensure that the electrodes and the separator are fully wetted. After the battery is left standing, formed, and secondarily sealed, the preparation of the lithium-ion battery is completed.

[0099] This embodiment also provides an electrical device that uses the battery prepared in the above embodiment.

[0100] The following is a further detailed description of the performance detection of the positive current collector prepared in the embodiments of the present invention through specific experiments as examples.

[0101] Experimental Example 1

[0102] S1. Raw materials of Fe 0.15%, Si 0.04%, Cu 0.05%, Ti 0.04%, Zn 0.05%, Al 99.655%, and Mn 0.015% are put into a high-temperature furnace for melting, and the temperature of the high-temperature furnace is 700 °C.

[0103] S2. Casting.

[0104] The melted aluminum alloy forms an aluminum ingot through a casting process. After casting is completed, the aluminum ingot is cooled to room temperature.

[0105] S3. Rolling and annealing.

[0106] The aluminum ingot obtained in step S2 is rolled so that the thickness of the aluminum foil is 15 μm, and annealing is performed.

[0107] S4. Using lithium iron phosphate powder as the positive electrode active material, the positive electrode active material, carbon nanotubes, polyvinylidene fluoride (PVDF), and N-methylpyrrolidone (NMP) are mixed in a mass ratio of 100:2:3:50 to prepare a positive electrode slurry. The positive electrode slurry is coated on the aluminum foil obtained in step S3 and dried to obtain a positive electrode sheet.

[0108] S5. The positive electrode sheet, negative electrode sheet, and separator are sequentially and orderly laminated to obtain a core.

[0109] S6. After the core is jacketed, an electrolyte is injected, and a lithium-ion battery is obtained through formation and grading.

[0110] Experimental Example 2

[0111] The preparation method of the lithium-ion battery in Example 2 is the same as that in Example 1, except that raw materials of Fe 0.15%, Si 0.04%, Cu 0.05%, Ti 0.04%, Mg 0.05%, Al 99.656%, and Mn 0.014% are used.

[0112] Experimental Example 3

[0113] The preparation method of the lithium-ion battery in Example 3 is the same as that in Example 1, except that raw materials of Fe 0.15%, Si 0.04%, Cu 0.05%, Ti 0.04%, Zr 0.05%, Al 99.656%, and Mn 0.014% are used.

[0114] Experimental Example 4

[0115] The preparation method of the lithium-ion battery in Example 4 is the same as that in Example 1, except that raw materials of Fe 0.15%, Si 0.04%, Cu 0.05%, Ti 0.04%, Zn 0.05%, Mg 0.05%, Al 99.606%, and Mn 0.014% are used.

[0116] Experimental Example 5

[0117] The preparation method of the lithium-ion battery in Example 5 is the same as that in Example 1, except that raw materials of Fe 0.15%, Si 0.04%, Cu 0.05%, Ti 0.04%, Zn 0.05%, Zr 0.05%, Al 99.606%, and Mn 0.014% are used.

[0118] Experimental Example 6

[0119] The preparation method of the lithium-ion battery in Example 6 is the same as that in Example 1, except that raw materials of Fe 0.15%, Si 0.04%, Cu 0.05%, Ti 0.04%, Mg 0.05%, Zr 0.05%, Al 99.606%, and Mn 0.014% are used.

[0120] Experimental Example 7

[0121] Raw materials of Fe 0.15%, Si 0.04%, Cu 0.05%, Ti 0.04%, Zn 0.04%, Mg 0.03%, Zr 0.03%, Al 99.621%, and Mn 0.014% are used.

[0122] Experimental Example 8

[0123] Use raw materials of Fe 0.15%, Si 0.04%, Cu 0.05%, Ti 0.04%, Zn 0.03%, Al 99.676%, Mn 0.014%.

[0124] Experimental Example 9

[0125] Use raw materials of Fe 0.15%, Si 0.04%, Cu 0.05%, Ti 0.04%, Zn 0.10%, Al 99.606%, Mn 0.014%.

[0126] Experimental Example 10

[0127] Use raw materials of Fe 0.1%, Si 0.02%, Cu 0.05%, Ti 0.04%, Zn 0.04%, Mg 0.03%, Zr 0.03%, Al 99.681%, Mn 0.009%.

[0128] Comparative Example 1

[0129] Use raw materials of Fe 0.10%, Si 0.02%, Cu 0.05%, Ti 0.04%, Zr 0.12%, Al 99.656%, Mn 0.014%.

[0130] Comparative Example 2

[0131] Use raw materials of Fe 0.4%, Si 0.15%, Cu 0.15%, Ti 0.04%, Zn 0.05%, Mg 0.05%, Al 99.146%, Mn 0.014%.

[0132] Comparative Example 3

[0133] Use raw materials of Fe 0.15%, Si 0.04%, Cu 0.04%, Ti 0.04%, Zn 0.01%, Mg 0.01%, Al 99.696%, Mn 0.014%.

[0134] It should be noted that the impurity elements can also be trace elements such as Sn, Ag, Ga, Ge, As, Gd, In, Pb, Bi, Hg, Sr, Ca, Na, S, P, V, Cr, Ni, K, B, etc. that have no significant effect on the tensile strength and conductivity of the aluminum foil.

[0135] The contents of each element in the above experimental examples and comparative examples are as follows:

[0136] Table 1

[0137] Example Fe / % Si / % Cu / % Ti / % Zn / % Mg / % Zr / ％ Al / ％ Mn / % Experimental Example 1 0.15 0.04 0.05 0.04 0.05 / / 99.656 0.014 Experimental Example 2 0.15 0.04 0.05 0.04 / 0.05 / 99.656 0.014 Experimental Example 3 0.15 0.04 0.05 0.04 / / 0.05 99.656 0.014 Experimental Example 4 0.15 0.04 0.05 0.04 0.05 0.05 / 99.606 0.014 Experimental Example 5 0.15 0.04 0.05 0.04 0.05 / 0.05 99.606 0.014 Experimental Example 6 0.15 0.04 0.05 0.04 / 0.05 0.05 99.606 0.014 Experimental Example 7 0.15 0.04 0.05 0.04 0.04 0.03 0.03 99.621 0.014 Experimental Example 8 0.15 0.04 0.05 0.04 0.03 / / 99.676 0.014 Experimental Example 9 0.15 0.04 0.05 0.04 0.10 / / 99.606 0.014 Experimental Example 10 0.1 0.02 0.05 0.04 0.04 0.03 0.03 99.681 0.009 Comparative Example 1 0.1 0.02 0.05 0.04 / / 0.12 99.656 0.014 Comparative Example 2 0.4 0.15 0.15 0.04 0.05 0.05 / 99.146 0.014 Comparative Example 3 0.15 0.04 0.04 0.04 0.01 0.01 / 99.696 0.014

[0138] Based on the above experimental examples and comparative examples, tensile strength tests and electrical conductivity tests were performed.

[0139] The test method is as follows:

[0140] Tensile strength and elongation test method: refer to GB / T 3076-2019 "Tensile test method for thin plates and thin strips of metal materials", where the specimen width is 15mm, the tensile spacing is 50mm, and the tensile speed is 10mm / min.

[0141] Process yield (including rolling yield) test method: the yield of the entire process from coating to the end of the battery cell production line, with a focus on the yield of the rolling process.

[0142] Internal resistance test method: Charge the battery at 0.2C to a voltage of 4.2V at 25℃, leave it for 30min, then discharge it at a discharge rate of 0.2C to a voltage of 2.5V, cycle it 3 times in sequence, and take the third charge and discharge data as the battery capacity; then charge it at 0.2C to 50% SOC; place the battery at 25℃, set 0.2C and 0.5C charging for 30s respectively, record the termination voltage and termination current of each process, and calculate the DCIR of each process.

[0143] Puncture test method: refer to the puncture test requirements in GB / T 31467.3-2015 "Safety requirements for power batteries for electric vehicles Part 3: Safety requirements for power battery modules and systems".

[0144] Among them, the test result evaluation is defined as: when the actual test value is less than 85% of the target value, the performance is considered to be at the D level; when the actual test value is greater than or equal to 85% of the target value and less than 95% of the target value, the performance is considered to be at the C level; when the actual test value is greater than or equal to 95% of the target value and less than 105% of the target value, the battery performance is considered to be at the B level; when the actual test value is greater than or equal to 105% of the target value, the battery performance is considered to be at the A level.

[0145] Specifically, in the examples and comparative examples of the present application, the process yield target is 90%, the DCIR target at 25° C. is 950 mΩ, and the needle puncture pass rate target is 90%.

[0146] Among them, the test results are as follows:

[0147] Table 2

[0148]

[0149]

[0150] Based on Table 2, it can be seen from Examples 1 - 10 and Comparative Examples 1 - 3 that the Al element content in Examples 1 - 10 is ≥99.6%, and the corresponding conductivity value is 36×10 6 S / m; the Al element content in Comparative Example 2 is 99.146%, and the corresponding conductivity value is 34.5×10 6 S / m; therefore, it is determined that the higher the Al element content, the higher the conductivity, and vice versa, the lower the Al element content, the lower the conductivity.

[0151] The tensile strength of Examples 1 - 10 is 230 MPa, and the needling results are good. However, the tensile strength of Comparative Example 3 is 200 MPa, and the needling results are inferior to those of Examples 1 - 10. The main reason for the analysis is that the total content of Zn, Mg, and Zr added in Comparative Example 3 is small, and the tensile strength cannot be improved, resulting in poor needling results. Therefore, adding a certain content of Zn, Mg, and Zr elements is beneficial to improving the tensile strength and needling results of the aluminum foil.

[0152] In addition, comparing Examples 1 - 10 and Comparative Example 1 with the same Al content, although the tensile strength, conductivity, internal resistance, and needling effect are the same, the elongation rate of Comparative Example 1 is poor, and the process yield is poor. The analysis shows that this is caused by a higher Zr content. The effects presented by the added Zn, Mg, and Zr in the experiments not disclosed in this application are not very different, and they can be considered to have the same effect and not be distinguished. Therefore, it is necessary to limit the total addition range of Zn, Mg, and Zr not to exceed 0.1%.

[0153] On the basis of maintaining an aluminum content of 99.6%, the aluminum foil of this patent successfully increases the tensile strength to more than 230 MPa. This not only maintains the advantages of high purity but also ensures excellent conductivity, thus avoiding an increase in the internal resistance of the battery.

[0154] Compared with the prior art, this patent avoids the drawbacks of other alloy elements, improves the tensile strength without reducing the conductivity, enhances the material properties while still maintaining high - efficiency conductive performance, has no adverse effect on the internal resistance of the battery, and at the same time improves the process yield. The high - strength current collector provided by this patent shows excellent needling passing rate in the needling test, significantly improves the safety of the battery under extreme conditions, and reduces the risk of short - circuit and thermal runaway.

[0155] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention, which follow the general principles of the present invention and include known common general knowledge or conventional technical means in the technical field not disclosed in the present invention. It is not limited to the precise structures described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. An aluminum material, characterized in that, The aluminum material includes: one or more of Zn, Mg, and Zr with a total mass percentage of 0.03%-0.1%, and Al with a mass percentage ≥99.6%; The composition of the aluminum material further includes impurity elements, and the mass percentage of each impurity element <0.015%.

2. The aluminum material according to claim 1, characterized in that, The aluminum material further includes: Fe with a mass percentage ≤0.3%; and / or, Si with a mass percentage ≤0.1%; and / or, Cu with a mass percentage ≤0.1%; and / or, Ti with a mass percentage ≤0.05%.

3. The aluminum material according to claim 2, characterized in that, The aluminum material further includes: Fe with a mass percentage ≤0.15%; and / or, Si with a mass percentage ≤0.04%; and / or, Cu with a mass percentage ≤0.05%; and / or, Ti with a mass percentage ≤0.04%.

4. An aluminum foil, characterized in that, including the aluminum material according to any one of claims 1-3.

5. The aluminum foil according to claim 4, wherein The thickness of the aluminum foil is 10-20 microns.

6. The aluminum foil according to claim 4 or 5, characterized in that, The tensile strength of the aluminum foil is greater than or equal to 230 Mpa, the elongation is greater than or equal to 3.0%, and the conductivity is greater than or equal to 36*10 6 S / m.

7. A method for preparing aluminum foil, characterized in that, including the following steps: S1. Melting the aluminum material according to any one of claims 1-3; S2. Casting; S3. Rolling and annealing.

8. A positive current collector, characterized in that, The positive current collector includes the aluminum foil according to any one of claims 4-6 or the aluminum foil prepared by the preparation method according to claim 7.

9. A positive electrode sheet, characterized in that, including a positive current collector and a positive active material layer provided on at least one side of the positive current collector, and the positive current collector uses the positive current collector according to claim 8.

10. A battery, characterized in that, including the positive electrode plate according to claim 9.

11. An electrical device, characterized in that, including the battery according to claim 10.

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