Aluminum foil and preparation method thereof, pole piece, battery, battery pack and electric equipment

Abstract

The invention provides an aluminum foil and a preparation method thereof, a pole piece, a battery, a battery pack and electric equipment. The aluminum foil comprises an aluminum element, rare earth elements, an iron element and a silicon element, the aluminum element accounts for more than or equal to 99.0 wt% of the mass of the aluminum foil, the rare earth elements comprise yttrium and cerium, the rare earth elements account for less than or equal to 0.17 wt% of the mass of the aluminum foil, the iron element accounts for 0.01-0.5 wt% of the mass of the aluminum foil, and the silicon element accounts for 0.01-0.5 wt% of the mass of the aluminum foil. And the silicon element accounts for 0.01 wt%-0.15 wt% of the mass of the aluminum foil. The aluminum foil has good conductivity and corrosion resistance, and the safety of the battery can be effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of batteries and relates to an aluminum foil, and more particularly to an aluminum foil and its preparation method, an electrode, a battery, a battery pack and an electrical device. Background Technology

[0002] In the design and manufacture of aluminum foil for batteries, different alloying elements are often added to the aluminum matrix to enhance its mechanical and processing properties. However, the addition of alloying elements often leads to a decrease in the conductivity of pure aluminum. Simultaneously, aluminum foil is prone to corrosion during prolonged high-voltage electrochemical cycling, resulting in problems such as delamination of the active material and current collector, increased internal resistance, and electrolyte decomposition, ultimately causing a decrease in battery power and capacity.

[0003] Therefore, it is necessary to develop a new type of aluminum foil to effectively improve its conductivity and corrosion resistance. Summary of the Invention

[0004] To address the aforementioned shortcomings, this invention provides an aluminum foil with good conductivity and corrosion resistance, which can effectively improve battery safety.

[0005] The present invention also provides a preparation method, wherein the aluminum foil prepared by the preparation method has good conductivity and corrosion resistance, which can effectively improve the safety of the battery.

[0006] The present invention also provides an electrode sheet comprising an active material layer and the above-mentioned aluminum foil, or an aluminum foil prepared by the above-mentioned preparation method, thus the battery has high safety.

[0007] The present invention also provides a battery comprising a separator, an electrolyte, and the aforementioned aluminum foil, or an aluminum foil prepared by the aforementioned preparation method, or the aforementioned electrode sheet, thus the battery has high safety.

[0008] The present invention also provides a battery pack, including the above-mentioned electrode or the above-mentioned battery, and therefore the battery pack has high safety.

[0009] The present invention also provides an electrical device, including the above-mentioned electrode, or the above-mentioned battery, or the above-mentioned battery pack, and therefore the electrical device has high safety.

[0010] The first aspect of this invention provides an aluminum foil comprising aluminum, rare earth elements, iron, and silicon, wherein aluminum accounts for more than or equal to 99.0 wt% of the aluminum foil by mass, the rare earth elements include yttrium and cerium, the rare earth elements account for less than or equal to 0.17 wt% of the aluminum foil by mass, the iron elements account for 0.01 wt% to 0.5 wt% of the aluminum foil by mass, and the silicon elements account for 0.01 wt% to 0.15 wt% of the aluminum foil by mass.

[0011] As described above, the rare earth elements account for 0.01wt%-0.15wt% of the aluminum foil by mass.

[0012] As described above, the yttrium content of the aluminum foil is less than or equal to 0.07 wt%, preferably 0.005 wt% to 0.05 wt%.

[0013] As described above, the cerium element accounts for less than or equal to 0.12 wt% of the aluminum foil by mass, preferably 0.005 wt% to 0.10 wt%.

[0014] The aluminum foil as described above includes copper, with the copper content in the aluminum foil being less than or equal to 0.07 wt%, preferably 0.01 wt% to 0.05 wt%.

[0015] The aluminum foil described above satisfies any of the following conditions: a) the aluminum foil includes titanium, and the titanium content of the aluminum foil is 0.01 wt% to 0.2 wt% by mass; b) the aluminum foil includes additives, and the additives include at least one of manganese, zinc, and magnesium, and the additives content of the aluminum foil is 0.01 wt% to 0.2 wt% by mass; c) other impurities account for less than or equal to 0.2 wt% by mass of the aluminum foil.

[0016] The aluminum foil as described above has a thickness of less than or equal to 25 μm, preferably 10 μm-20 μm.

[0017] The second aspect of the present invention provides a method for preparing aluminum foil, comprising the following steps: mixing an aluminum source, a rare earth source, an iron source, and a silicon source in the proportions described in the first aspect, and processing to obtain aluminum foil.

[0018] The aluminum foil preparation method described above satisfies at least one of the following conditions: i) the process includes casting and rolling at a speed of 0.5 m / min to 4 m / min; ii) the process includes cold rolling at a speed of 400 m / min to 1200 m / min; iii) the process includes annealing at a temperature of 400°C to 600°C for a time of 8 h to 12 h; and iii) the process includes foil rolling at a speed of 600 m / min to 1000 m / min.

[0019] The aluminum foil preparation method described above is carried out according to the following steps: (1) casting and rolling; (2) cold rolling; (3) annealing; (4) cold rolling; and (5) foil rolling.

[0020] A third aspect of the present invention provides an electrode sheet comprising an active material layer and an aluminum foil as described in the first aspect, or an aluminum foil prepared by the preparation method described in the second aspect.

[0021] A fourth aspect of the present invention provides a battery comprising a separator, an electrolyte, and an aluminum foil as described in the first aspect, or an aluminum foil prepared by the preparation method described in the second aspect, or an electrode sheet as described in the third aspect.

[0022] The fifth aspect of the present invention provides a battery pack, including electrodes as described in the third aspect or a battery as described in the fourth aspect.

[0023] The sixth aspect of the present invention provides an electrical device, including, as in the third aspect, an electrode, as in the fourth aspect, a battery, or as in the fifth aspect, a battery pack.

[0024] The aluminum foil of this invention comprises aluminum, rare earth elements, iron, and silicon. Aluminum accounts for at least 99.0 wt% of the aluminum foil by mass. The rare earth elements, including yttrium and cerium, account for at least 0.17 wt% of the aluminum foil by mass. Iron accounts for 0.01 wt%-0.5 wt% of the aluminum foil by mass, and silicon accounts for 0.01 wt%-0.15 wt% of the aluminum foil by mass. The addition of yttrium and cerium improves the distribution of impurities such as Fe and Si in the aluminum foil, reduces eutectic structures at grain boundaries, and thus enhances the conductivity of the aluminum foil. Simultaneously, they participate in the formation of the passivation layer, maintaining its stability and improving the corrosion resistance of the aluminum foil. Therefore, the aluminum foil of this invention, while meeting application requirements, exhibits good conductivity and corrosion resistance, significantly improving battery safety. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0026] In the design and manufacture of aluminum foil for batteries, different alloying elements are often added to the aluminum matrix to enhance its mechanical and processing properties. However, the addition of alloying elements often leads to a decrease in the conductivity of pure aluminum. Simultaneously, aluminum foil is prone to corrosion during prolonged high-voltage electrochemical cycling, resulting in problems such as delamination of the active material and current collector, increased internal resistance, and electrolyte decomposition, causing a decline in battery power and capacity. Therefore, it is necessary to develop a new type of aluminum foil to effectively improve its conductivity and corrosion resistance.

[0027] The inventors discovered through research that the addition of rare earth elements yttrium and cerium can improve the distribution of Fe and Si in aluminum foil. This is because, on the one hand, yttrium and cerium have a stronger affinity for Fe and Si than aluminum, and can preferentially react with Fe and Si to form fine, dispersed high-melting-point rare earth intermetallic compounds (such as CeFe2, CeFe5, YFe3, etc.) or rare earth silicides (such as CeSi2), replacing the originally harmful needle-like or plate-like iron-rich phases (such as Al). σ (Fe). Simultaneously, rare earth elements can adsorb onto the surface of these rare earth compounds, reducing their surface energy, inhibiting their growth and agglomeration, and resulting in a more uniform and finer distribution. These fine rare earth compounds then act as heterogeneous nucleation sites in the melt, promoting the refinement of aluminum foil grains. On the other hand, rare earth elements yttrium and cerium can form a passivation film on the aluminum foil surface, improving the density and stability of the passivation film, reducing electrolyte penetration, and enhancing the corrosion resistance of the aluminum foil.

[0028] Therefore, the addition of rare earth elements yttrium and cerium can improve the distribution of Fe and Si in the aluminum foil, promote grain refinement, and reduce eutectic structures at grain boundaries, thereby improving the conductivity of the aluminum foil. Simultaneously, they can also participate in the formation of the passivation layer, maintaining its stability and thus improving the corrosion resistance of the aluminum foil. Therefore, the aluminum foil in this invention can meet application requirements while exhibiting good conductivity and corrosion resistance, significantly improving battery safety.

[0029] Based on the above analysis, the first aspect of the present invention provides an aluminum foil comprising aluminum, rare earth elements, iron, and silicon, wherein the aluminum element accounts for more than or equal to 99.0 wt% of the aluminum foil by mass, the rare earth elements include yttrium and cerium, the rare earth elements account for less than or equal to 0.17 wt% of the aluminum foil by mass, the iron element accounts for 0.01 wt% to 0.5 wt% of the aluminum foil by mass, and the silicon element accounts for 0.01 wt% to 0.15 wt% of the aluminum foil by mass.

[0030] It is understandable that adding rare earth elements such as yttrium and cerium to aluminum foil can improve the distribution of Fe, Si, etc. in the aluminum foil, reduce the eutectic structure at the grain boundaries, and thus improve the conductivity of the aluminum foil. At the same time, it can also participate in the formation of the passivation layer, maintain the stability of the passivation layer, and thus improve the corrosion resistance of the aluminum foil.

[0031] For example, the mass percentage of aluminum in the aluminum foil can be 99 wt%, 99.10 wt%, 99.20 wt%, 99.30 wt%, 99.40 wt%, 99.50 wt%, 99.60 wt%, 99.70 wt%, 99.80 wt%, 99.90 wt%, 99.99 wt%, or 99.999 wt%, or a range of any two of these values. When the mass percentage of aluminum in the aluminum foil is within the above range, the aluminum foil has good corrosion resistance and formability, and can better meet the requirements of batteries for corrosion resistance and surface treatment of aluminum foil.

[0032] For example, the mass percentage of rare earth elements in the aluminum foil can be 0.01 wt%, 0.05 wt%, 0.10 wt%, 0.15 wt%, or 0.17 wt%, or any combination of two of these values. When the mass percentage of rare earth elements in the aluminum foil is greater than or equal to 0.01 wt%, rare earth compounds can be formed, replacing the harmful iron-rich phase and simultaneously forming a stable passivation layer. When the mass percentage of rare earth elements in the aluminum foil is less than or equal to 0.17 wt%, it ensures that the rare earth compounds form fine grains, preventing grain growth and segregation, and avoiding brittle fracture of the aluminum foil. Therefore, when the mass percentage of rare earth elements in the aluminum foil is within the above range, fine rare earth compounds can be formed, creating a stable passivation film and improving the conductivity and corrosion resistance of the aluminum foil.

[0033] For example, the mass percentage of iron in the aluminum foil can be 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt%, or 0.5 wt%, or any range of two of these values. When the mass percentage of iron in the aluminum foil is greater than or equal to 0.01 wt%, the iron can form fine, dispersed intermetallic compounds in the aluminum foil, improving the strength and hardness of the aluminum foil. When the mass percentage of iron in the aluminum foil is less than or equal to 0.5 wt%, it can ensure the ductility and impact resistance of the aluminum foil, preventing aluminum foil failure. When the mass percentage of iron in the aluminum foil is within the above ranges, both advantages are achieved.

[0034] For example, the mass percentage of silicon in the aluminum foil can be 0.01 wt%, 0.05 wt%, 0.1 wt%, or 0.15 wt%, or any range of two of these values. When the mass percentage of silicon in the aluminum foil is greater than or equal to 0.01 wt%, silicon can be dissolved in the aluminum foil, improving its strength and hardness. When the mass percentage of silicon in the aluminum foil is less than or equal to 0.15 wt%, it ensures the ductility and impact resistance of the aluminum foil, preventing foil failure. When the mass percentage of silicon in the aluminum foil is within the above ranges, both advantages are achieved.

[0035] Therefore, the aluminum-plastic film in this invention has high resistance to electrochemical corrosion while meeting application requirements.

[0036] The percentages of aluminum, rare earth elements, iron, and silicon in the aluminum foil by mass were determined using inductively coupled plasma mass spectrometry (ICP-MS). The specific procedure is as follows:

[0037] Place a 0.1g aluminum foil sample in a polytetrafluoroethylene digestion vessel, add digestion solution (5ml 65% nitric acid + 2ml 36% hydrochloric acid), seal, and microwave digest at 150-180℃. After cooling, transfer the digestion solution and dilute to a 50ml volumetric flask with ultrapure water. Prepare a series of standard solutions containing aluminum, yttrium, cerium, iron, and silicon. Establish a standard curve by sequentially testing the blank solution and standard solutions, and then select isotopes. 27 Al、 89 Y、 140 Ce、 56 Fe、 28 The device monitors the signal intensity of aluminum, yttrium, cerium, iron, and silicon in a sample solution and automatically calculates the elemental content of each element.

[0038] In one specific embodiment, the rare earth elements account for 0.01wt%-0.15wt% of the mass of the aluminum foil.

[0039] For example, the mass percentage of rare earth elements in the aluminum foil can be 0.01 wt%, 0.05 wt%, 0.10 wt%, or 0.15 wt%, or any range of two of these values. The effect is better when the mass percentage of rare earth elements in the aluminum foil is within the above range.

[0040] In one specific embodiment, the yttrium element accounts for less than or equal to 0.07 wt% of the aluminum foil, preferably 0.005 wt% to 0.05 wt%.

[0041] For example, the mass percentage of yttrium in the aluminum foil can be 0.001 wt%, 0.005 wt%, 0.01 wt%, 0.02 wt%, 0.03 wt%, 0.04 wt%, 0.05 wt%, or 0.07 wt%, or any range of two such values. When the mass percentage of yttrium in the aluminum foil is greater than or equal to 0.001 wt%, a stable and dense passivation layer can be formed on the surface of the aluminum foil, reducing electrolyte penetration. When the mass percentage of yttrium in the aluminum foil is less than or equal to 0.07 wt%, the aluminum foil has good ductility. Therefore, when the mass percentage of yttrium in the aluminum foil is within the above range, the conductivity and corrosion resistance of the aluminum foil can be improved. The effect is even better when the mass percentage of yttrium in the aluminum foil is in the range of 0.005 wt% to 0.05 wt%.

[0042] In one specific embodiment, the cerium element accounts for less than or equal to 0.12 wt% of the aluminum foil, preferably 0.005 wt% to 0.10 wt%.

[0043] For example, the mass percentage of cerium in the aluminum foil can be 0.001 wt%, 0.005 wt%, 0.01 wt%, 0.02 wt%, 0.03 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.10 wt%, or 0.12 wt%, or any range of two such values. When the mass percentage of cerium in the aluminum foil is greater than or equal to 0.001 wt%, a stable and dense passivation layer can be formed on the surface of the aluminum foil, reducing electrolyte penetration. When the mass percentage of cerium in the aluminum foil is less than or equal to 0.12 wt%, the aluminum foil has better ductility. Therefore, when the mass percentage of cerium in the aluminum foil is within the above range, the conductivity and corrosion resistance of the aluminum foil can be improved. The effect is even better when the mass percentage of cerium in the aluminum foil is in the range of 0.005 wt% to 0.10 wt%.

[0044] In one specific embodiment, the aluminum foil includes copper, and the copper content of the aluminum foil is less than or equal to 0.07 wt%, preferably 0.01 wt% to 0.05 wt%.

[0045] For example, the mass percentage of copper in the aluminum foil can be 0.01 wt%, 0.02 wt%, 0.04 wt%, 0.05 wt%, or 0.07 wt%, or any range of two such values. When the mass percentage of copper in the aluminum foil is greater than or equal to 0.01 wt%, it can improve the electron mobility of the aluminum foil, reduce resistivity, improve the conductivity and tensile strength of the aluminum foil, and reduce processing cracks. When the mass percentage of copper in the aluminum foil is less than or equal to 0.07 wt%, it can reduce the occurrence of electrochemical corrosion and improve the corrosion resistance of the aluminum foil. Therefore, when the mass percentage of copper in the aluminum foil is within the above range, the aluminum foil can balance conductivity and corrosion resistance. The effect is even better when the mass percentage of copper in the aluminum foil is in the range of 0.01 wt% to 0.05 wt%.

[0046] Similarly, the method for determining the percentage of copper in aluminum foil by mass is the same as that for determining the percentage of aluminum in aluminum foil by mass, and will not be repeated here.

[0047] In one specific embodiment, the aluminum foil satisfies any of the following conditions: a) the aluminum foil includes titanium, and the titanium content of the aluminum foil is 0.01 wt% to 0.2 wt% by mass; b) the aluminum foil includes additive elements, including at least one of manganese, zinc, and magnesium, and the additive elements account for 0.01 wt% to 0.2 wt% by mass; c) other impurities account for less than or equal to 0.2 wt% by mass of the aluminum foil.

[0048] For example, the mass percentage of titanium in the aluminum foil can be 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.15 wt%, or 0.2 wt%, or any range of two such values. When the mass percentage of titanium in the aluminum foil is greater than or equal to 0.01 wt%, titanium can refine the grains, improving the strength and ductility of the aluminum foil. When the mass percentage of titanium in the aluminum foil is less than or equal to 0.2 wt%, it can ensure the ductility and impact resistance of the aluminum foil, preventing foil failure. When the mass percentage of titanium in the aluminum foil is within the above ranges, both advantages are achieved.

[0049] For example, the added element's mass percentage of the aluminum foil can be 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.15 wt%, or 0.2 wt%, or any range of two such values. When the added element's mass percentage of the aluminum foil is greater than or equal to 0.01 wt%, the added element can improve the strength and ductility of the aluminum foil; when the added element's mass percentage of the aluminum foil is less than or equal to 0.2 wt%, it can ensure the ductility and impact resistance of the aluminum foil, preventing aluminum foil failure. When the added element's mass percentage of the aluminum foil is within the above ranges, both advantages are achieved.

[0050] Similarly, the test methods for the percentage of titanium in aluminum foil by mass and the percentage of added elements in aluminum foil by mass are the same as those for the percentage of aluminum in aluminum foil by mass, and will not be repeated here.

[0051] For example, the percentage of other impurities by mass of the aluminum foil can be 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.15 wt%, or 0.2 wt%, or a range consisting of any two of these values. When the percentage of other impurities by mass of the aluminum foil is within the above range, it can be ensured that the various properties of the aluminum foil meet the requirements and will not have a negative impact on the aluminum foil.

[0052] In one specific embodiment, the thickness of the aluminum foil is less than or equal to 25 μm, preferably 10 μm-20 μm.

[0053] For example, the thickness of the aluminum foil can be 1μm, 10μm, 13μm, 16μm, 20μm, or 25μm, or any range of two such values. When the thickness of the aluminum foil is greater than or equal to 1μm, it exhibits good impact resistance; when the thickness is less than or equal to 25μm, it exhibits good ductility. Therefore, when the thickness of the aluminum foil is within the above range, both impact resistance and ductility can be balanced. The effect is even better when the thickness of the aluminum foil is in the range of 10μm-20μm.

[0054] The specific procedures for testing the thickness of aluminum foil are as follows:

[0055] The coating on the surface of the battery electrode is removed to obtain aluminum foil, which is then cut into pieces with an area S of 15 cm². 2 The mass M of the disc sample to be tested is obtained by weighing. Thickness = M / (ρ) 铝 *S)*10 4 The unit is μm, where ρ aluminum is taken as 2.7 g / cm³. 3 .

[0056] A second aspect of the present invention provides a method for preparing aluminum foil according to the first aspect, comprising the following steps:

[0057] Aluminum source, rare earth source, iron source and silicon source are mixed in the proportions described in the above embodiments, and then processed to obtain aluminum foil.

[0058] Specifically, in one embodiment, at least one of the following conditions is met: i) the process includes casting and rolling at a speed of 0.5 m / min to 4 m / min; ii) the process includes cold rolling at a speed of 400 m / min to 1200 m / min; iii) the process includes annealing at a temperature of 400°C to 600°C for a time of 8 h to 12 h; and iiii) the process includes foil rolling at a speed of 600 m / min to 1000 m / min.

[0059] In this invention, the purity and mechanical properties of aluminum foil can be improved by controlling the preparation process during the treatment process.

[0060] For example, the process includes casting and rolling, and the casting and rolling speed can be 0.5 m / min, 1 m / min, 1.5 m / min, 2 m / min, 2.5 m / min, 3 m / min, 3.5 m / min or 4 m / min, or a range of any two of these values.

[0061] For example, the process includes cold rolling, and the cold rolling speed can be 400 m / min, 500 m / min, 600 m / min, 700 m / min, 800 m / min, 900 m / min, 1000 m / min, 1100 m / min or 1200 m / min, or a range of any two of these values.

[0062] For example, the process includes annealing, the annealing temperature being 400°C, 450°C, 500°C, 550°C, or 600°C, or a range of any two of these values; the annealing time being 8h, 9h, 10h, 11h, or 12h, or a range of any two of these values.

[0063] For example, the process includes foil rolling, and the foil rolling speed can be 600 m / min, 700 m / min, 800 m / min, 900 m / min or 1000 m / min, or a range of any two of these values.

[0064] Specifically, in one embodiment, the process is carried out according to the following steps: (1) performing the casting and rolling; (2) performing the cold rolling; (3) performing the annealing; (4) performing the cold rolling; and (5) performing the foil rolling.

[0065] Understandably, processing aluminum foil according to the above steps can optimize the microstructure, further refine the grains, improve the work hardening effect, and enhance the overall performance of the aluminum foil.

[0066] In this invention, before the above-mentioned processing steps, the following steps can be performed to improve the purity and mechanical strength of the aluminum foil: Aluminum source, rare earth source, iron source, and silicon source are mixed and melted in a melting furnace in a certain proportion until they reach a liquid state. The melting time is 30-60 minutes, and the temperature is controlled at 700℃-800℃. Then, the mixture is refined for 10-60 minutes under an inert atmosphere, with the addition of a refining agent to absorb impurities from the melting process. After holding at 700℃-800℃ for 1-2 hours, degassing and filtration are performed to remove impurities.

[0067] A third aspect of the present invention provides an electrode sheet comprising an active material layer and an aluminum foil as described in the first aspect, or an aluminum foil prepared by the preparation method of the second aspect. Therefore, the electrode sheet has good conductivity and corrosion resistance.

[0068] The active material layer can be any active material layer conventionally used in the art, and the present invention does not limit it.

[0069] A fourth aspect of the present invention provides a battery comprising a separator, an electrolyte, and an aluminum foil as described in the first aspect, or an aluminum foil prepared by the method of the second aspect, or an electrode sheet as described in the third aspect. Therefore, this battery has high safety.

[0070] It should be noted that the battery in this invention can be a pouch battery or a blade battery; specifically, the aforementioned battery can be any alkali metal ion battery such as a lithium-ion battery or a sodium-ion battery. More specifically, the aforementioned battery can be a liquid battery using a liquid electrolyte, or a solid-state battery or a semi-solid-state battery. The positive electrode, negative electrode, and electrolyte in the battery can be any known positive electrode, negative electrode, and electrolyte in a corresponding battery.

[0071] The separator can be any separator commonly used in the art, and the present invention does not limit it.

[0072] The electrolyte can be any electrolyte commonly used in the art, whether it is a solid electrolyte or a liquid electrolyte, and the present invention does not limit it.

[0073] A fifth aspect of the present invention provides a battery pack, comprising the electrode sheet of the third aspect or the battery of the fourth aspect. Therefore, the battery pack has high safety.

[0074] Generally, a battery pack includes multiple (at least one) of the aforementioned batteries. It can be a battery pack composed of the aforementioned batteries and conventional batteries, or it can be a battery pack composed of two or more of the aforementioned batteries. These batteries, as individual units, are connected to form the battery pack. These batteries can be electrically connected using methods conventional in the art, such as series connection, parallel connection, or a hybrid connection including both of these methods, without particular limitation.

[0075] The sixth aspect of the present invention provides an electrical device, including an electrode sheet as described in the third aspect, a battery as described in the fourth aspect, or a battery pack as described in the fifth aspect, thereby the electrical device having a long service life and high safety.

[0076] This invention does not impose any specific limitations on the types of electrical equipment, including but not limited to 3C electronic consumer products such as mobile phones, laptops, tablets, and smartwatches.

[0077] The following detailed description of the aluminum-plastic film and the battery including the aluminum-plastic film provided by the present invention will be provided through specific embodiments.

[0078] Example 1

[0079] 1) Smelting and refining. The alloying elements are prepared according to a mass ratio of aluminum:yttrium:cerium:copper:other alloying elements = 99:0.05:0.01:0.01:0.93. The mass ratio of other alloying elements is iron, silicon, titanium, magnesium, zinc, manganese = 7:2:3:1:1:1. First, the above materials are smelted in a furnace at 800℃ for 60 minutes. Then, a refining agent is added, and the mixture is refined for 60 minutes under an argon atmosphere. After holding at 800℃ for 2 hours, degassing and filtration are performed to remove impurities, yielding molten aluminum.

[0080] 2) Processing. The molten aluminum is cast and rolled at a speed of 2 m / min to form an aluminum billet with a thickness of 5 mm. After casting and rolling, the aluminum billet is cooled to room temperature. Then, it is cold rolled for two passes at a speed of 1000 m / min, followed by annealing at a temperature of 600℃ for 12 hours. This is followed by two more cold rolling passes at a speed of 1000 m / min to obtain a cold-rolled billet with a thickness of 1 mm. Finally, it is foil rolled for four passes at room temperature at a speed of 1000 m / min to produce aluminum foil with a thickness of 15 μm.

[0081] Example 2

[0082] The preparation method of aluminum foil in this embodiment is basically the same as that in Example 1, except that in step 1), the amount of yttrium is 0.002 and the amount of cerium is 0.002.

[0083] Example 3

[0084] The preparation method of aluminum foil in this embodiment is basically the same as that in Example 1, except that in step 1), the amount of yttrium is 0.005 and the amount of cerium is 0.005.

[0085] Example 4

[0086] The preparation method of aluminum foil in this embodiment is basically the same as that in Example 1, except that in step 1), the amount of yttrium is 0.050 and the amount of cerium is 0.100.

[0087] Example 5

[0088] The preparation method of aluminum foil in this embodiment is basically the same as that in Example 1, except that in step 1), the amount of yttrium is 0.070 and the amount of cerium is 0.100.

[0089] Example 6

[0090] The preparation method of aluminum foil in this embodiment is basically the same as that in Example 1, except that in step 1), the amount of yttrium is 0.050 and the amount of cerium is 0.120.

[0091] Example 7

[0092] The preparation method of aluminum foil in this embodiment is basically the same as that in Example 1, except that in step 1), the amount of cerium is 0.100 and yttrium is not present.

[0093] Example 8

[0094] The preparation method of aluminum foil in this embodiment is basically the same as that in Example 1, except that in step 1), the amount of yttrium is 0.050 and cerium is not present.

[0095] Example 9

[0096] The preparation method of aluminum foil in this embodiment is basically the same as that in Example 1, except that the amount of copper in step 1) is 0.050.

[0097] Example 10

[0098] The preparation method of aluminum foil in this embodiment is basically the same as that in Example 1, except that the amount of copper in step 1) is 0.070.

[0099] Example 11

[0100] The method for preparing aluminum foil in this embodiment is basically the same as that in Example 1. The difference is that in step 2), the thickness of the aluminum foil is controlled to be 5 μm in the final foil rolling process.

[0101] Example 12

[0102] The method for preparing aluminum foil in this embodiment is basically the same as that in Example 1. The difference is that in step 2), the thickness of the aluminum foil is controlled to be 10 μm in the final foil rolling process.

[0103] Example 13

[0104] The method for preparing aluminum foil in this embodiment is basically the same as that in Example 1. The difference is that in step 2), the thickness of the aluminum foil is controlled to be 20 μm in the final foil rolling process.

[0105] Example 14

[0106] The method for preparing aluminum foil in this embodiment is basically the same as that in Example 1. The difference is that in step 2), the thickness of the aluminum foil is controlled to be 25 μm in the final foil rolling process.

[0107] Example 15

[0108] The preparation method of aluminum foil in this embodiment is basically the same as that in Example 1, except that in step 1), the proportion of aluminum is 99.6, the proportion of yttrium is 0.005, and the proportion of cerium is 0.005.

[0109] Example 16

[0110] The preparation method of aluminum foil in this embodiment is basically the same as that in Example 1. The difference is that in step 1), the amount of yttrium is 0.005, the amount of cerium is 0.005, and copper is not present.

[0111] Example 17

[0112] The preparation method of aluminum foil in this embodiment is basically the same as that in Example 1. The difference is that in step 1), the amount of yttrium is 0.070, the amount of cerium is 0.120, the amount of iron is 0.533, the amount of silicon is 0.267, and titanium, magnesium, zinc and manganese are not present.

[0113] Comparative Example 1

[0114] The preparation method of the aluminum foil in this comparative example is basically the same as that in Example 1, except that it does not contain yttrium or cerium.

[0115] Comparative Example 2

[0116] The preparation method of the aluminum foil in this comparative example is basically the same as that in Example 1, except that the proportion of aluminum is 99.6, and it does not contain yttrium or cerium.

[0117] Test case

[0118] Battery assembly: Using lithium iron phosphate as the positive electrode material, a slurry made of positive electrode material, conductive agent and binder in a certain proportion is coated onto the aluminum foil prepared in the examples and comparative examples, and then dried to obtain a positive electrode sheet. Using graphite as the negative electrode material, a negative electrode sheet is prepared in the same way. Using 1 mol / L lithium hexafluorophosphate carbonate solution as the electrolyte, the positive electrode sheet, separator and negative electrode sheet are stacked in sequence to assemble a lithium-ion battery.

[0119] (1) Physical property testing

[0120] 1. Mass percentage of an element

[0121] The test was performed using inductively coupled plasma mass spectrometry (ICP-MS), and the specific procedure is as follows:

[0122] Place a 0.1g aluminum foil sample in a polytetrafluoroethylene digestion vessel, add digestion solution (5ml 65% nitric acid + 2ml 36% hydrochloric acid), seal, and microwave digest at 150-180℃. After cooling, transfer the digestion solution and dilute to a 50ml volumetric flask with ultrapure water. Prepare a series of standard solutions containing aluminum, yttrium, cerium, iron, silicon, copper, titanium, manganese, zinc, and magnesium. Establish a standard curve by sequentially testing the blank solution and standard solutions, and then select isotopes. 27 Al、 89 Y、 140 Ce、 56 Fe、 28 Si、 63 Cu、 48 Ti、 55 Mn, 66 Zn, 24 The Mg monitors the signal intensity of aluminum, yttrium, cerium, iron, silicon, copper, titanium, manganese, zinc, and magnesium elements in a sample solution. The equipment automatically calculates the content of each element.

[0123] 2. Thickness of aluminum foil

[0124] The coating on the surface of the battery electrode is removed to obtain aluminum foil, which is then cut into pieces with an area S of 15 cm². 2 The mass M of the disc sample to be tested is obtained by weighing. Thickness = M / (ρ) 铝 *S)*10 4 The unit is μm, where ρ aluminum is taken as 2.7 g / cm³. 3 .

[0125] Table 1

[0126] Serial Number Al / wt% Y / wt% Ce / wt% Cu / wt% Fe / wt% Si / wt% Ti / wt% Mg / wt% Zn / wt% Mn / wt% Aluminum foil thickness / μm Example 1 99 0.050 0.010 0.01 0.434 0.124 0.186 0.062 0.062 0.062 15 Example 2 99 0.002 0.002 0.01 0.460 0.131 0.197 0.066 0.066 0.066 15 Example 3 99 0.005 0.005 0.01 0.457 0.131 0.196 0.065 0.065 0.065 15 Example 4 99 0.050 0.100 0.01 0.392 0.112 0.168 0.056 0.056 0.056 15 Example 5 99 0.070 0.100 0.01 0.383 0.109 0.164 0.055 0.055 0.055 15 Example 6 99 0.050 0.120 0.01 0.383 0.109 0.164 0.055 0.055 0.055 15 Example 7 99 / 0.100 0.01 0.415 0.119 0.178 0.059 0.059 0.059 15 Example 8 99 0.050 / 0.01 0.439 0.125 0.188 0.063 0.063 0.063 15 Example 9 99 0.050 0.010 0.05 0.415 0.119 0.178 0.059 0.059 0.059 15 Example 10 99 0.050 0.010 0.07 0.406 0.116 0.174 0.058 0.058 0.058 15 Example 11 99 0.050 0.010 0.01 0.434 0.124 0.186 0.062 0.062 0.062 5 Example 12 99 0.050 0.010 0.01 0.434 0.124 0.186 0.062 0.062 0.062 10 Example 13 99 0.050 0.010 0.01 0.434 0.124 0.186 0.062 0.062 0.062 20 Example 14 99 0.050 0.010 0.01 0.434 0.124 0.186 0.062 0.062 0.062 25 Example 15 99.6 0.005 0.005 0.01 0.177 0.051 0.076 0.025 0.025 0.025 15 Example 16 99 0.005 0.005 / 0.462 0.132 0.198 0.066 0.066 0.066 15 Example 17 99 0.070 0.120 0.01 0.533 0.267 / / / / 15 Comparative Example 1 99 / / 0.01 0.462 0.132 0.198 0.066 0.066 0.066 15 Comparative Example 2 99.6 / / 0.01 0.182 0.052 0.078 0.026 0.026 0.026 15

[0127] (2) Electrochemical performance testing

[0128] 1. DCIR

[0129] Charge the battery at 0.2C to 4.3V at 25℃, let it rest for 30 minutes, then discharge it at 0.2C to 2.5V. Repeat this cycle three times, and take the data from the third charge / discharge cycle as the battery capacity. Then charge it at 0.2C to 50% SOC. Place the battery at 25℃ for 2 hours, then discharge it at 1.5C for 30 seconds. Let it rest for 10 minutes, and record the last voltage data as V1. Charge it at 1.5C for 30 seconds, and record the last data as V2. Calculate the DCIR.

[0130] DCIR = (V2 - V1) / 1.5C * 1000 (unit: mΩ) 2. Corrosion Potential

[0131] Remove the battery electrodes and separate the aluminum foil sample. Perform cyclic voltammetry on the aluminum foil at 25°C. The test potential range is 2.0V-4.3V, the scan speed is 2mV / s, and the number of cycles is 20. Record the corrosion potential of the aluminum foil.

[0132] 3. Tensile strength and elongation

[0133] Refer to GB / T 3076-2019 "Metallic Materials - Thin Plates and Strips - Tensile Testing Methods", where the strip width is 15 mm, the tensile spacing is 50 mm, and the tensile speed is 10 mm / min.

[0134] Table 2

[0135] Serial Number DCIR / mΩ Corrosion potential / V Tensile strength / MPa Elongation / % Example 1 750 4.56 230.1 3.51 Example 2 844 4.21 230.1 3.51 Example 3 812 4.32 230.1 3.50 Example 4 839 4.21 230.1 3.51 Example 5 879 4.05 230.0 3.50 Example 6 996 3.94 229.9 3.49 Example 7 950 3.89 229.9 3.50 Example 8 1003 3.72 229.8 3.50 Example 9 758 4.22 230.1 3.51 Example 10 823 3.79 229.9 3.49 Example 11 867 4.20 229.9 3.48 Example 12 779 4.30 230.1 3.51 Example 13 707 4.29 230.1 3.52 Example 14 705 4.19 229.9 3.50 Example 15 801 4.29 220.0 3.41 Example 16 953 3.74 230.0 3.50 Example 17 1004 3.75 230.0 3.51 Comparative Example 1 1486 3.54 229.7 3.47 Comparative Example 2 1548 3.27 219.8 3.38

[0136] Combining Table 1 and Table 2, we can see that:

[0137] Compared to Comparative Example 1, the batteries in Examples 1-14 all exhibited good conductivity and corrosion resistance while maintaining good mechanical properties.

[0138] Based on the above analysis, it can be seen that the aluminum-plastic film in this invention has good resistance to electrochemical corrosion, which can effectively improve the safety of the battery.

[0139] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An aluminum foil, characterized in that, The aluminum foil comprises aluminum, rare earth elements, iron, and silicon. The aluminum element accounts for more than or equal to 99.0 wt% of the aluminum foil by mass. The rare earth elements include yttrium and cerium, and the rare earth elements account for less than or equal to 0.17 wt% of the aluminum foil by mass. The iron element accounts for 0.01 wt% to 0.5 wt% of the aluminum foil by mass. The silicon element accounts for 0.01 wt% to 0.15 wt% of the aluminum foil by mass.

2. The aluminum foil according to claim 1, characterized in that, The rare earth elements account for 0.01 wt% to 0.15 wt% of the mass of the aluminum foil.

3. The aluminum foil according to claim 1 or 2, characterized in that, The yttrium content of the aluminum foil is less than or equal to 0.07 wt%, preferably 0.005 wt% to 0.05 wt%.

4. The aluminum foil according to claim 1 or 2, characterized in that, The cerium element accounts for less than or equal to 0.12 wt% of the mass of the aluminum foil, preferably 0.005 wt% to 0.10 wt%.

5. The aluminum foil according to any one of claims 1-4, characterized in that, The aluminum foil includes copper, and the copper content of the aluminum foil is less than or equal to 0.07 wt%, preferably 0.01 wt% to 0.05 wt%.

6. The aluminum foil according to any one of claims 1-5, characterized in that, The aluminum foil satisfies any of the following conditions: a) The aluminum foil includes titanium, and the titanium content of the aluminum foil is 0.01wt%-0.2wt% by mass; b) The aluminum foil includes additive elements, including at least one of manganese, zinc, and magnesium, and the additive elements account for 0.01wt%-0.2wt% of the mass of the aluminum foil; c) Other impurities account for less than or equal to 0.2 wt% of the mass of the aluminum foil.

7. The aluminum foil according to any one of claims 1-6, characterized in that, The thickness of the aluminum foil is less than or equal to 25 μm, preferably 10 μm-20 μm.

8. A method for preparing aluminum foil, characterized in that, Includes the following steps: The aluminum source, rare earth source, iron source, and silicon source are mixed in the proportions described in any one of claims 1-7, and then processed to obtain the aluminum foil.

9. The method for preparing aluminum foil according to claim 8, characterized in that, At least one of the following conditions must be met: i) The process includes casting and rolling at a speed of 0.5 m / min to 4 m / min; ii) The process includes cold rolling at a speed of 400 m / min to 1200 m / min; iii) The process includes annealing, wherein the annealing temperature is 400℃-600℃ and the annealing time is 8h-12h; iiii) The process includes foil rolling at a speed of 600 m / min to 1000 m / min.

10. The method for preparing aluminum foil according to claim 9, characterized in that, The process is performed according to the following steps: (1) Perform the aforementioned casting and rolling; (2) Perform the aforementioned cold rolling; (3) Perform the annealing process; (4) Perform the cold rolling process; (5) Perform the foil rolling.

11. An electrode sheet, characterized in that, It includes an active material layer and an aluminum foil as described in any one of claims 1-7, or an aluminum foil prepared by any one of claims 8-10.

12. A battery, characterized in that, It includes a separator, an electrolyte, and an aluminum foil as described in any one of claims 1-7, or an aluminum foil prepared by any one of claims 8-10, or an electrode as described in claim 11.

13. A battery pack, characterized in that, Includes the electrode as described in claim 11, or the battery as described in claim 12.

14. An electrical appliance, characterized in that, This includes the electrode sheet as described in claim 11, the battery as described in claim 12, or the battery pack as described in claim 13.