Positive electrode current collector rolling oil, preparation method, positive electrode current collector, secondary battery and electric device

Abstract

The invention provides positive electrode current collector rolling oil, a preparation method, a positive electrode current collector, a secondary battery and an electric device. The rolling oil comprises a fatty alcohol compound, a fatty acid ester compound and base oil, wherein based on the total mass of the rolling oil, the mass content of the fatty alcohol compound is 1.0%-3.0%, and the mass content of the fatty acid ester compound is 6.5%-10.0%. The rolling oil can improve the missed coating proportion of the aqueous ceramic material on the surface of the positive electrode current collector.

Description

Technical Field

[0001] The present application relates to the technical field of secondary batteries, and in particular to a positive electrode current collector rolling oil, a preparation method, a positive electrode current collector, a secondary battery, and an electrical device. Background Art

[0002] Secondary batteries are widely used in various consumer electronics and electric vehicles due to their lightweight, pollution-free, and memory-free features. With the continuous development of the new energy industry, users have placed higher demands on the reliability and performance of secondary batteries.

[0003] The positive electrode of a secondary battery consists of a current collector and a positive electrode film layer coated on at least one side of the current collector. During the rolling process, rolling oil is used to improve the surface quality of the current collector. However, the use of rolling oil can affect the coating of the positive electrode slurry, causing leakage on the current collector surface, increasing the internal resistance of the battery cell, and compromising the safety of the secondary battery.

[0004] Therefore, there are still deficiencies and room for improvement in the existing technology, and it is necessary to provide a new positive electrode current collector rolling oil. Summary of the Invention

[0005] The present application provides a positive electrode current collector rolling oil, which can improve the ratio of leaked coating of water-based positive electrode coating materials on the surface of aluminum foil.

[0006] In the first aspect, the positive electrode current collector rolling oil provided in the present application includes: a fatty alcohol compound, a fatty acid ester compound and a base oil; wherein, based on the total mass of the rolling oil, the mass content of the fatty alcohol compound is 1.0% to 3.0%, and the mass content of the fatty acid ester compound is 6.5% to 10.0%. In the rolling oil, the fatty acid ester compound can form an oil film with stable adsorption performance on the surface of the current collector, which is beneficial to the process stability during the rolling process, reducing the rolling oil temperature and the risk of fire caused by the current collector rolling breakage; however, the fatty acid ester compound can reduce the wettability of the current collector surface, which is not conducive to the spreading of the positive electrode coating material, especially the positive electrode insulating material. The fatty alcohol compound can form a thin and easily desorbed oil film on the surface of the current collector, improve the wettability of the current collector surface and increase the spreading of the positive electrode coating slurry on its surface, reduce the leakage of the positive electrode insulating material (for example, the ceramic material coated between the current collector and the positive electrode active material), thereby reducing the safety risk of the battery cell caused by leakage short circuit.

[0007] In any embodiment, the mass content of the fatty alcohol compound is 1.0% to 2.0% based on the total mass of the rolling oil, which further improves the spreading of the positive electrode insulating material on the surface of the current collector and reduces the proportion of missed coating of the positive electrode insulating material, especially the water-based ceramic material.

[0008] In any embodiment, the mass content of fatty acid ester compounds is 6.0% to 9.0% based on the total mass of the rolling oil, and can be optionally 6.5% to 8.0%, thereby further improving the lubricity of the rolling oil, maintaining the stability of the rolling process, and reducing the rolling oil temperature and the risk of rolling belt breakage and fire.

[0009] In any embodiment, the viscosity of the rolling oil is less than or equal to 2.1 mm 2 / s, optional 1.95mm 2 / s~2.1mm 2 / s, which can improve the rolling speed of aluminum foil.

[0010] In any embodiment, the mass content of the gum in the rolling oil is less than or equal to 1000 mg / 100 ml, and can be optionally less than 800 mg / 100 ml, which helps to improve the quality and lubrication effect of the rolling oil.

[0011] In any embodiment, the base oil includes at least one of 80# base oil, 95# base oil, 90# base oil, and 100# base oil, and the base oil helps to reduce the amount of oil on the surface of the aluminum foil and improve the oil temperature during the rolling process.

[0012] In any embodiment, the positive electrode current collector is selected from aluminum current collectors.

[0013] In any embodiment, the fatty alcohol compound has a C10-C14 aliphatic hydrocarbon group, which is beneficial to improving the desorption of the oil film and reducing the amount of oil on the current collector surface. In any embodiment, the fatty acid end and the fatty alcohol end of the fatty acid ester compound each independently have a C6-C10 aliphatic hydrocarbon group, which is beneficial to improving the spreading of the rolling oil on the current collector surface.

[0014] A second aspect of the present application provides a method for preparing a positive electrode current collector, comprising the following steps:

[0015] The positive electrode current collector blank is subjected to rough rolling and intermediate rolling to obtain an intermediate current collector; the intermediate current collector is subjected to finish rolling using positive electrode current collector rolling oil, and is cut into pieces to obtain a positive electrode current collector;

[0016] The positive electrode current collector rolling oil comprises: fatty alcohol compounds, fatty acid ester compounds and base oil; wherein, based on the total mass of the rolling oil, the mass content of the fatty alcohol compounds is 1.0% to 3.0%, and the mass content of the fatty acid ester compounds is 6.5% to 10.0%.

[0017] The preparation method helps to control and reduce the amount of oil on the surface of the positive electrode current collector, thereby improving the coating effect of the positive electrode current collector and reducing the phenomenon of coating leakage.

[0018] In any embodiment, the preparation method further comprises a corona treatment. In any embodiment, the corona treatment is performed after the slitting process. The corona treatment helps to improve the surface condition of the current collector and further reduce the phenomenon of missing coating.

[0019] In any embodiment, at least one of the following conditions is met during the corona treatment:

[0020] (1) Corona power is 30KW~60KW;

[0021] (2) The corona speed is 100 m / min to 260 m / min, and can be 150 m / min to 260 m / min; and / or

[0022] (3) The number of corona discharges does not exceed 2 times.

[0023] The preparation method can avoid or reduce the number of corona treatments, and the surface of the prepared current collector has a low oil content, which not only reduces energy consumption but also improves the spreading performance of the positive electrode insulating material, especially the water-based ceramic material, on the current collector surface, and increases production capacity.

[0024] In any embodiment, during the finishing rolling process, the roller roughness of the finishing rolling pass is 0.08 μm to 0.15 μm, and can be optionally 0.08 μm to 0.13 μm, thereby improving the adhesion of the positive electrode insulating material to the current collector surface.

[0025] A third aspect of the present application provides a positive electrode current collector prepared by the method described in the second aspect of the present application. In any embodiment, the roughness of the positive electrode current collector is 0.1 μm to 0.3 μm, which helps improve the coating quality of the positive electrode material in the secondary battery, reduce the proportion of uncoated materials, and thus improve the safety performance of the secondary battery.

[0026] The fourth aspect of the present application provides a secondary battery comprising the positive electrode current collector prepared by the method of the second aspect of the present application and the positive electrode current collector provided by the third aspect of the present application. In some embodiments, the positive electrode active material of the secondary battery comprises an olivine-structured lithium-containing phosphate.

[0027] A fifth aspect of the present application provides an electrical device comprising the secondary battery according to the fourth aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A and B show the coating photos of the aluminum foil coated with the water-based positive electrode ceramic slurry in Comparative Example 1 and Example 1 of the present application, respectively;

[0029] Figure 2 is a schematic diagram of a secondary battery according to one embodiment of the present application;

[0030] Figure 3 yes Figure 2 An exploded view of a secondary battery according to an embodiment of the present application is shown;

[0031] Figure 4 is a schematic diagram of a battery module according to one embodiment of the present application;

[0032] Figure 5 is a schematic diagram of a battery pack according to one embodiment of the present application;

[0033] Figure 6 yes Figure 5 An exploded view of a battery pack according to an embodiment of the present application is shown;

[0034] Figure 7 FIG. 1 is a schematic diagram of an electrical device using a secondary battery according to an embodiment of the present application as a power source.

[0035] Description of reference numerals:

[0036] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 secondary battery; 51 shell; 52 electrode assembly; 53 cover plate. DETAILED DESCRIPTION

[0037] Below, the embodiments of the positive electrode active material and its manufacturing method, positive electrode sheet, secondary battery, battery module, battery pack and electrical device of the present application are specifically disclosed in detail with appropriate reference to the drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0038] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0039] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0040] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0041] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0042] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0043] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0044] The current collector is an important component of the positive electrode of a secondary battery, and the surface quality of the current collector can affect the performance of the secondary battery. The current collector blank has a large friction coefficient and high pressure during the rolling process, which can generate a large amount of deformation heat and friction heat, which can cause damage to the surface of the current collector and even lead to unqualified plate shape. Rolling oil can play the purpose of lubrication and cooling during the rolling process of the current collector blank, reduce the friction during the rolling process, take away the heat generated during the rolling process, provide a stable friction interface and achieve stable rolling, and improve the surface quality of the current collector. However, secondary batteries, especially positive electrode current collectors for lithium-ion secondary batteries, such as aluminum foil, usually do not have cleaning and baking processes in industrial production, and the rolling oil remaining on its surface can affect the adhesion between the positive electrode coating material and the current collector.

[0045] During the preparation of lithium-ion batteries, especially lithium iron phosphate secondary batteries, it is usually necessary to coat the surface of the positive electrode current collector with an insulating material, followed by the positive electrode active material, to reduce the risk of die-cutting burrs and burr short circuits, thereby improving the safety of the secondary battery and improving the cycling performance of the battery cell. Aqueous insulating materials are widely used in lithium-ion batteries because they are simple to prepare and cause little environmental pollution. However, due to the significant polarity difference between aqueous insulating materials and rolling oils, they have poor adhesion to the current collector surface, resulting in omissions during the coating process. This not only increases the internal resistance of the battery cell and reduces the cycling performance of the secondary battery, but also easily leads to short circuits in the current collector, compromising the safety of the secondary battery.

[0046] [Positive electrode current collector rolling oil]

[0047] Based on this, the first aspect of this application proposes a positive electrode current collector rolling oil, which can improve the adhesion of positive electrode coating materials, especially water-based insulating materials on the surface of the positive electrode current collector, reduce the proportion of water-based insulating materials missing from the surface of the positive electrode current collector, and improve the safety of secondary batteries.

[0048] The secondary battery positive electrode collector rolling oil provided in the present application includes: fatty alcohol compounds, fatty acid ester compounds and base oil; wherein, based on the total mass of the rolling oil, the mass content of the fatty alcohol compounds is 1.0% to 3.0%, and the mass content of the fatty acid ester compounds is 6.5% to 10.0%.

[0049] As used herein, "fatty alcohols" refers to saturated monohydric or polyhydric alcohols with a backbone containing from six to 14 carbon atoms, where the backbone refers to the longest carbon chain containing a hydroxyl group. The aliphatic hydrocarbon group (the carbon chain group after removing the hydroxyl group) in a fatty alcohol can be straight or branched.

[0050] In some embodiments, the fatty alcohol compound has an aliphatic hydrocarbon group with 10 to 14 carbon atoms (C10-C14), and these carbon atoms can be covalently linked in the form of a straight chain or a branched chain. In some embodiments, the fatty alcohol compound includes a straight chain aliphatic hydrocarbon group with 10 to 14 carbon atoms. In some embodiments, the fatty alcohol compound includes a branched chain aliphatic hydrocarbon group with 10 to 14 carbon atoms and a main chain aliphatic hydrocarbon group with more than six carbon atoms.

[0051] In some embodiments, the fatty alcohol compound is a pure substance. In some embodiments, the fatty alcohol compound is a mixture. In some embodiments, the fatty alcohol compound is a compound having a saturated monohydric alcohol and / or polyhydric alcohol with C10 to C14.

[0052] The fatty alcohol compound has good lubrication properties, is beneficial to reducing friction during the rolling process, provides a stable friction interface, achieves stable rolling and improves the surface quality of the positive electrode current collector.

[0053] As used herein, "fatty acid ester compounds" refer to ester compounds obtained by esterification of fatty acid compounds and fatty alcohol compounds. "Fatty acid compounds" refer to saturated monobasic or polybasic acids with a main chain containing from six to 14 carbon atoms. The fatty chain in the fatty acid compound can be straight or branched. In fatty acid ester compounds, the main chain carbon atom counts of the aliphatic hydrocarbon group derived from the fatty acid compound (or fatty acid end) and the aliphatic hydrocarbon group derived from the fatty alcohol compound (or fatty alcohol end) can be the same or different; the carbon atom counts of the fatty chain at the fatty acid end and the fatty chain at the fatty alcohol end can be the same or different.

[0054] In some embodiments, the fatty acid end and the fatty alcohol end of the fatty acid ester compound each independently have a C6-C10 aliphatic hydrocarbon group, and these carbon atoms can be covalently linked in the form of a straight chain or a branched chain. In some embodiments, the fatty acid end and the fatty alcohol end of the fatty acid ester compound each independently include a straight chain or a branched chain of 6 to 10 carbon atoms. In some embodiments, the fatty acid end and the fatty alcohol end of the fatty acid compound each independently are a class of compounds of saturated monobasic acid esters and / or polybasic acid esters having 6 to 10 carbon atoms.

[0055] In some embodiments, the fatty acid ester compound is a pure substance. In some embodiments, the fatty acid ester compound is a mixture.

[0056] The fatty acid ester compound having the fatty chains of the fatty acid compound and the fatty alcohol compound has good thermal stability, low volatility during the rolling process, is not easy to form oil spots, and further reduces the wear of the aluminum material during the rolling process.

[0057] As used herein, "straight chain" and "branched chain" have meanings commonly known in the art.

[0058] Under rolling pressure, the two oxygen atoms contained in the polar group ester group in the fatty acid ester compound form an intermolecular force with the metal atoms (such as aluminum atoms) in the positive electrode current collector. Therefore, the fatty acid ester compound can form a relatively thick and high-strength oil film on the surface of the positive electrode current collector, realizing the separation or basic separation of the rolling roller and the positive electrode current collector, which can reduce the friction during the rolling process, provide a stable friction interface, be beneficial to the process stability during the rolling process and improve the surface quality of the positive electrode current collector. In addition, the fatty chain in the fatty acid ester compound has good thermal stability and heat conduction ability, which helps to reduce the rolling oil temperature and the risk of fire caused by rolling fracture. However, the good adhesion performance of the fatty acid ester compound on the current collector surface causes the fatty acid ester compound to be difficult to desorb, which can reduce the wettability of the current collector surface, which is unfavorable for the spreading of positive electrode insulating materials, especially water-based positive electrode insulating materials (such as ceramic material boehmite).

[0059] The fatty alcohol compounds in the rolling oil contain an oxygen atom in the polar group hydroxyl group, which causes the oil film formed by the fatty alcohol compounds on the surface of the positive electrode current collector to be thin (relative to the thickness of the oil film formed by fatty acid ester compounds), relatively weak in strength and easy to desorb. The thin and weak oil film is not conducive to reducing the loss of the blank (such as aluminum), but it helps to reduce the degree of oil on the surface of the current collector, thereby improving the wettability of the surface of the positive electrode current collector and improving the spreading performance and adhesion of the positive electrode insulating material (for example, ceramic material) on the surface of the positive electrode current collector. It can reduce the proportion of the positive electrode insulating material and the positive active slurry on the surface of the current collector that is not coated, improve the quality stability of the secondary battery and reduce safety risks.

[0060] The compounding of fatty alcohol compounds and fatty acid ester compounds can improve the lubricity of the blank during the rolling process, and improve the adhesion and spreading performance of aqueous insulating materials, especially aqueous ceramic materials, on the surface of the positive electrode current collector while improving the surface quality of the positive electrode current collector.

[0061] In some embodiments, the mass content of the fatty alcohol compound is 1.0% to 2.0% based on the total mass of the rolling oil. In some embodiments, the mass content of the fatty alcohol compound is 1.0%, 1.3%, 1.6%, 1.9%, 2.2%, 2.5%, 2.7%, 3.0%, or a range between any two of the above values based on the total mass of the rolling oil. The mass content of the fatty alcohol compound within the above range can further increase the proportion of rolling oil desorbed from the current collector surface, reduce the amount of oil on the current collector surface and improve its surface wettability, thereby improving the spreading and adhesion of the positive electrode slurry on the positive electrode current collector surface and reducing the proportion of positive electrode slurry leaks; it also helps to improve the lubrication performance of the rolling oil, improve rolling losses, and improve the surface quality of the current collector.

[0062] In some embodiments, the mass content of the fatty acid ester compound is 6.0% to 9.0% based on the total mass of the rolling oil. In some embodiments, the mass content of the fatty acid ester compound is 6.5% to 8.0% based on the total mass of the rolling oil. In some embodiments, the mass content of the fatty acid ester compound is 6.7%, 7.0%, 7.3%, 7.8%, 8.0%, 8.3%, 8.6%, 9.0%, 9.3%, 9.6%, 10.0% or a range between any two of the above values based on the total mass of the rolling oil. The mass content of the fatty acid ester compound within the above range can enable the rolling oil to form a high-strength oil film on the surface of the positive electrode current collector, reduce the friction coefficient between the rolling roll and the current collector, reduce raw material loss and further maintain the stability of the rolling process; it also helps to reduce the temperature of the rolling oil and the risk of fire caused by rolling belt breakage during the rolling process, and helps to control the plate shape.

[0063] In some embodiments, based on the total mass of the rolling oil, the mass content of the fatty alcohol compound is 1.0% to 2.0%, and the mass content of the fatty acid ester compound is 6.0% to 9.0%.

[0064] In some embodiments, the viscosity of the rolling oil is less than or equal to 2.1 mm 2 In some embodiments, the viscosity of the rolling oil is 1.75 mm 2 / s~2.1mm 2 / s、1.80mm 2 / s~2.1mm 2 / s、1.85mm 2 / s~2.1mm 2 / s、1.90mm 2 / s~2.1mm 2 / s、1.95mm 2 / s~2.1mm 2 / s, thereby reducing the slowing effect of rolling oil on rolling speed and improving the rolling speed of the positive electrode current collector; it also helps to adjust the heat transfer performance of rolling oil and improve oil temperature control during rolling.

[0065] The viscosity of the rolling oil can be measured using any method known in the art, for example, using a capillary viscometer or a rotational viscometer.

[0066] Rolling oil may deteriorate or be mixed with other mechanical lubricants (such as hydraulic oil and grease) during long-term storage or use. Some of the substances in the oil may polymerize to form unwanted high-molecular compounds, which are collectively referred to as "colloids". These unwanted high-molecular compounds generally have aliphatic hydrocarbon groups with C15 to C50 or more carbon atoms. In some cases, these unwanted high-molecular compounds can also be called heavy oils, and their specific gravity is generally between 0.82 and 0.95. The level of gum content can indicate the severity of oil aging and / or contamination. Generally, the higher the gum content, the more aged and / or contaminated the oil is.

[0067] In some embodiments, the mass content of the colloid in the rolling oil is less than or equal to 1000 mg / 100 ml. In some embodiments, the mass content of the colloid in the rolling oil is less than 900 mg / 100 ml. In some embodiments, the mass content of the colloid in the rolling oil is less than 800 mg / 100 ml, which helps to improve the quality and lubrication effect of the rolling oil. The colloid content of the rolling oil can be measured using any method known in the art. For example, the national standard GB / T509 can be used to measure the colloid content.

[0068] In some embodiments, the rolling oil comprises a base oil, which may include animal fats, vegetable fats, or mineral oils. In some embodiments, the base oil is a mineral oil, such as an oil product extracted from petroleum by a physical distillation method. In some embodiments, the mineral oil comprises kerosene. In some embodiments, the mineral oil comprises gasoline.

[0069] In some embodiments, the base oil includes at least one of 80# base oil, 95# base oil, 90# base oil, and 100# base oil. In some embodiments, the base oil is 80# base oil.

[0070] Herein, "80#," "90#," "95#," and "100#" refer to base oil grades, indicating flash points of 80°C, 90°C, 95°C, and 100°C, respectively. The term "flash point" refers to the lowest temperature at which a liquid, under specific conditions, releases sufficient vapor to form a flammable mixture. The flash point of a substance can be determined using methods known in the art, for example, the Blinken open cup flash point test.

[0071] The base oil has relatively few polar molecules and weak surface adsorption capacity on the positive electrode current collector, which helps to reduce the amount of oil on the surface of the current collector; at the same time, it has good thermal conductivity and can improve the oil temperature during the rolling process.

[0072] The rolling oil provided in this application can be used for rough rolling, intermediate rolling and / or finishing rolling of a positive electrode current collector. In some embodiments, the rolling oil is used as a rough rolling oil for rough rolling of a secondary battery positive electrode current collector. In some embodiments, the rolling oil is used as an intermediate rolling oil for intermediate rolling of a secondary battery positive electrode current collector. In some embodiments, the rolling oil is used as a finishing oil for finishing rolling of a secondary battery positive electrode current collector, which helps to improve the phenomenon of leaking coating of the positive electrode slurry.

[0073] [Positive electrode current collector preparation method]

[0074] A second aspect of the present application provides a method for preparing a positive electrode current collector, comprising the following steps:

[0075] The positive electrode current collector blank is subjected to rough rolling and intermediate rolling to obtain a current collector intermediate product; the current collector intermediate product is subjected to finish rolling using positive electrode current collector rolling oil and cut to obtain the positive electrode current collector.

[0076] In some embodiments, the temperature of the rough rolling process is 30° C. to 50° C. In some embodiments, the temperature of the rough rolling process is 35° C. to 47° C.

[0077] In some embodiments, the roughing process has a roller roughness of 0.20 μm to 0.30 μm. In some embodiments, the roughing process has a roller roughness of 0.22 μm to 0.27 μm. In some embodiments, the roughing process has a roller roughness of 0.23 μm, 0.25 μm, 0.26 μm, 0.27 μm, or any range between two values.

[0078] In some embodiments, the rolling speed of the roughing process is 400 m / min to 500 m / min. In some embodiments, the rolling speed of the roughing process is 420 m / min to 480 m / min. In some embodiments, the rolling speed of the roughing process is 430 m / min, 450 m / min, 460 m / min, 470 m / min, or a range between any two values.

[0079] In some embodiments, the rough rolling process may use any commonly used or known rough rolling oil in the prior art to roll the positive electrode current collector.

[0080] In some embodiments, the rough rolling oil used in the rough rolling process includes: based on the total mass of the rolling oil, the mass content of fatty alcohol compounds is 2% to 5%, and the mass content of fatty acid ester compounds is 5% to 11%.

[0081] In some embodiments, the rough rolling oil used in the rough rolling process includes: based on the total mass of the rolling oil, the mass content of fatty alcohol compounds is 2% to 4%, and the mass content of fatty acid ester compounds is 5% to 10%.

[0082] In some embodiments, the rough rolling oil used in the rough rolling process includes: based on the total mass of the rolling oil, the mass content of fatty alcohol compounds is 2% to 4%, and the mass content of fatty acid ester compounds is 5% to 8%.

[0083] In some embodiments, the viscosity of the roughing oil used in the roughing process is less than 2.5 mm 2 In some embodiments, the viscosity of the roughing oil used in the roughing is less than 2.3 mm 2 In some embodiments, the viscosity of the roughing oil used in the roughing is less than 2.1 mm 2 / s.

[0084] In some embodiments, the gum content of the crude oil used in the roughing process is ≤1000 mg / 100 ml. In some embodiments, the gum content of the crude oil used in the roughing process is ≤900 mg / 100 ml. In some embodiments, the gum content of the crude oil used in the roughing process is ≤800 mg / 100 ml.

[0085] In some embodiments, the temperature of the intermediate rolling process is 30° C. to 50° C. In some embodiments, the temperature of the intermediate rolling process is 35° C. to 47° C.

[0086] In some embodiments, the roller roughness of the intermediate rolling process is 0.15 μm to 0.25 μm. In some embodiments, the roller roughness of the intermediate rolling process is 0.17 μm to 0.23 μm. In some embodiments, the roller roughness of the intermediate rolling process is 0.18 μm, 0.19 μm, 0.20 μm, 0.22 μm, or a range between any two values.

[0087] In some embodiments, the rolling speed of the intermediate rolling process is 450 m / min to 550 m / min. In some embodiments, the rolling speed of the intermediate rolling process is 470 m / min to 530 m / min. In some embodiments, the rolling speed of the intermediate rolling process is 480 m / min, 490 m / min, 500 m / min, 520 m / min, or a range between any two values.

[0088] In some embodiments, the intermediate rolling process may use any commonly used or known intermediate rolling oil in the prior art to roll the positive electrode current collector.

[0089] In some embodiments, the intermediate rolling oil used in the intermediate rolling process comprises: based on the total mass of the rolling oil, the mass content of fatty alcohol compounds is 2% to 6%, and the mass content of fatty acid ester compounds is 5% to 13%.

[0090] In some embodiments, the intermediate rolling oil used in the intermediate rolling process comprises: based on the total mass of the rolling oil, the mass content of fatty alcohol compounds is 2% to 4%, and the mass content of fatty acid ester compounds is 5% to 12%.

[0091] In some embodiments, the intermediate rolling oil used in the intermediate rolling process comprises: based on the total mass of the rolling oil, the mass content of fatty alcohol compounds is 2% to 5%, and the mass content of fatty acid ester compounds is 5% to 11%.

[0092] In some embodiments, the viscosity of the medium rolling oil used in the medium rolling process is less than 2.5 mm 2 In some embodiments, the viscosity of the medium rolling oil used in the medium rolling process is less than 2.3 mm 2 In some embodiments, the viscosity of the intermediate rolling oil used in the intermediate rolling process is less than 2.1 mm 2 / s.

[0093] In some embodiments, the gum content of the crude oil used in the intermediate rolling process is ≤1000 mg / 100 ml. In some embodiments, the gum content of the crude oil used in the intermediate rolling process is ≤900 mg / 100 ml. In some embodiments, the gum content of the crude oil used in the intermediate rolling process is ≤800 mg / 100 ml.

[0094] In some embodiments, the temperature of the finishing rolling process is 30°C to 55°C. In some embodiments, the temperature of the finishing rolling process is 30°C to 50°C. In some embodiments, the temperature of the finishing rolling process is 35°C to 50°C.

[0095] In some embodiments, the roller roughness of the finishing rolling process is 0.08 μm to 0.15 μm. In some embodiments, the roller roughness of the finishing rolling process is 0.08 μm to 0.14 μm. In some embodiments, the roller roughness of the finishing rolling process is 0.08 μm to 0.13 μm. In some embodiments, the roller roughness of the finishing rolling process is 0.09 μm, 0.10 μm, 0.11 μm, 0.12 μm, 0.13 μm, 0.14 μm, or a range between any two values, thereby improving the adhesion of the positive electrode slurry to the surface of the positive electrode current collector and improving the surface quality of the positive electrode current collector.

[0096] In some embodiments, the rolling speed of the finish rolling process is 500 m / min to 600 m / min. In some embodiments, the rolling speed of the finish rolling process is 520 m / min to 580 m / min. In some embodiments, the rolling speed of the finish rolling process is 530 m / min, 550 m / min, 560 m / min, 570 m / min, or a range between any two values, which can improve the production efficiency and production capacity of the positive electrode current collector.

[0097] In some embodiments, the finish rolling process may use any commonly used or known finishing oil in the prior art to roll the positive electrode current collector.

[0098] In some embodiments, the finishing rolling process may use the rolling oil provided in the first aspect of the present application.

[0099] After rough rolling, intermediate rolling and rough rolling, the current collector blank is rolled into a secondary battery positive electrode current collector with a good plate shape and good surface quality, which is conducive to improving the coating of the positive electrode slurry on the surface of the positive electrode current collector.

[0100] In some embodiments, the preparation method further includes a corona treatment. Corona treatment refers to the phenomenon of localized discharge on the surface of a charged body in a gas or liquid medium, which can generate substances such as ozone. Corona treatment can inhibit the polymerization of rolling oil on the surface of the positive electrode current collector, forming oil spots that easily lead to slurry leakage, thereby improving the surface quality of the positive electrode current collector.

[0101] In some embodiments, the power of the corona treatment is 30 kW to 70 kW. In some embodiments, the power of the corona treatment is 40 kW to 60 kW. In some embodiments, the power of the corona treatment is 50 kW to 60 kW. In some embodiments, the power of the corona treatment is 35 kW, 45 kW, 55 kW, 65 kW, 37 kW, or any range therebetween.

[0102] In some embodiments, the speed of the corona treatment is 100 m / min to 260 m / min. In some embodiments, the speed of the corona treatment is 150 m / min to 260 m / min. Generally, the lower the speed of the corona treatment, the more conducive it is to improving the coating quality of the slurry under the same coating conditions, but the reduced coating speed significantly affects production efficiency and reduces production capacity. The corona treatment speed in this application can take into account both production efficiency and production capacity while improving the coating quality of the aqueous positive electrode slurry.

[0103] In some embodiments, the number of corona treatments is no more than 2 times. In some embodiments, no corona treatment is required. In some embodiments, the number of corona treatments is 1 time. In some embodiments, the number of corona treatments is 2 times. In some embodiments, the number of corona treatments is 0 or 1 time. The method uses fewer corona treatments, which can reduce energy consumption and impact on production capacity during the preparation of the positive electrode current collector.

[0104] In some embodiments, the corona treatment is performed after the slitting process. Slitting refers to the process of punching (or cutting) the current collector into a predetermined size and shape. In order to improve the cross-section quality after punching, a fine cutting process may be performed after slitting to minimize burrs. In some embodiments, the corona treatment is performed after the fine cutting process. In some embodiments, the fine cutting process and the corona treatment are performed simultaneously.

[0105] The positive electrode current collector prepared by this method has a low oil content on its surface, improving the spreading performance of the positive electrode slurry, especially aqueous positive electrode slurry, on the positive electrode current collector surface. Corona treatment can further reduce the amount of oil on the positive electrode current collector surface, enhance the adhesion of the positive electrode slurry, and reduce the proportion of positive electrode slurry leaking on the positive electrode current collector surface.

[0106] On the other hand, the present application provides a secondary battery comprising a positive electrode current collector. Typically, a secondary battery comprises a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the battery's charge and discharge process, active ions are intercalated and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte acts as an ion conductor between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet, primarily to prevent a short circuit between the positive and negative electrodes while allowing ions to pass through.

[0107] The secondary battery, battery module, battery pack, and electric device of the present application are described below with reference to the accompanying drawings as appropriate.

[0108] [Positive electrode]

[0109] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes a positive electrode active material.

[0110] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0111] In some embodiments, the positive electrode current collector may be prepared by the above method. In some embodiments, the positive electrode current collector has a roughness of 0.1 μm to 0.3 μm, for example, 0.1 μm, 0.15 μm, 0.18 μm, 0.2 μm, 0.25 μm or 0.3 μm.

[0112] In some embodiments, the positive electrode active material may adopt the positive electrode active material for batteries that is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0113] In some embodiments, the positive electrode active material includes lithium iron phosphate.

[0114] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0115] In some embodiments, the positive electrode film layer may further include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0116] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0117] In some embodiments, before applying the positive electrode slurry to the positive electrode current collector, a ceramic material, such as boehmite, may be applied first. In some embodiments, the ceramic material may be prepared by dispersing it in an aqueous solvent (such as deionized water).

[0118] [Negative electrode]

[0119] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0120] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0121] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0122] In some embodiments, the negative electrode active material may be a negative electrode active material for a battery that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0123] In some embodiments, the negative electrode film layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0124] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0125] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0126] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0127] [Electrolytes]

[0128] The electrolyte conducts ions between the positive and negative electrodes. This application does not specify the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0129] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0130] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0131] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0132] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0133] [Isolation film]

[0134] In some embodiments, the secondary battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0135] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0136] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0137] In some embodiments, the secondary battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0138] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the secondary battery can be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0139] The present application has no particular restrictions on the shape of the secondary battery, which can be cylindrical, square or any other shape. For example, Figure 2 The secondary battery 5 is a square structure as an example.

[0140] In some embodiments, reference Figure 3 , the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. The number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0141] In some embodiments, secondary batteries can be assembled into a battery module. The number of secondary batteries contained in the battery module can be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0142] Figure 4 4 is an example of a battery module. Figure 4 In the battery module 4, the plurality of secondary batteries 5 may be arranged in sequence along the length of the battery module 4. Of course, they may also be arranged in any other manner. The plurality of secondary batteries 5 may further be fixed by fasteners.

[0143] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of secondary batteries 5 are received in the receiving space.

[0144] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0145] Figure 5 and Figure 6 The battery pack 1 is used as an example. Figure 5 and Figure 6 The battery pack 1 may include a battery box and multiple battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner in the battery box.

[0146] In addition, the present application also provides an electric device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application. The secondary battery, battery module, or battery pack can be used as a power source for the electric device, and can also be used as an energy storage unit for the electric device. The electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto.

[0147] As the electrical device, a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.

[0148] Figure 7 This is an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery, a battery pack or battery module can be used.

[0149] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is generally required to be lightweight and thin, and may use a secondary battery as a power source.

[0150] Example

[0151] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0152] 1. Preparation and coating of aluminum foil

[0153] Example 1

[0154] 1) Preparation of aluminum foil rolling oil

[0155] Rough rolling oil: Weigh fatty alcohol (purchased from Shijiazhuang Xintai Special Oil Co., Ltd., model STE12) and fatty acid ester (purchased from Shijiazhuang Xintai Special Oil Co., Ltd., model STE6) and add 80# base oil (purchased from Qingjiang Petrochemical Co., Ltd.), mix well, and the crude rolling oil is obtained. The quality control of the crude rolling oil meets the following requirements: based on the total mass of the rolling oil, the mass content of fatty alcohol is 3%, the mass content of fatty acid ester is 12.5%, and the viscosity is 2.1mm 2 / s, the mass content of colloid is 312mg / 100ml.

[0156] Medium rolling oil: Weigh fatty alcohol and fatty acid ester and add 80# base oil, mix well to obtain medium rolling oil. The quality control of medium rolling oil meets the following requirements: based on the total mass of rolling oil, the mass content of fatty alcohol is 3.5%, the content of fatty acid ester is 8%, and the viscosity is 2.03mm 2 / s, the mass content of colloid is 245mg / 100ml.

[0157] Finishing rolling oil: Weigh fatty alcohol and fatty acid ester and add 80# base oil, mix well to obtain finishing oil. The quality control of finishing oil meets the following requirements: based on the total mass of rolling oil, the mass content of fatty alcohol is 1%, the content of fatty acid ester is 8%, and the viscosity is <1.98mm 2 / s, the mass content of colloid is 195mg / 100ml.

[0158] 2) Rolling of aluminum foil

[0159] A. Rough rolling: The aluminum foil blank is subjected to rough rolling at a rough rolling temperature of 35-47° C., a roughness of 0.25 μm in the rough rolling pass, and a rolling speed of 450 m / min. The rough rolling oil prepared in 1) is used in the rough rolling process.

[0160] B. Intermediate rolling treatment: the intermediate rolling temperature is 35-47° C., the intermediate rolling pass roll roughness is 0.2 μm, the rolling speed is 500 m / min, and the intermediate rolling oil prepared in 1) is used in the intermediate rolling treatment.

[0161] C. Finishing rolling treatment: the finishing rolling temperature is 35-50° C., the roller roughness of the finished pass is 0.11 μm, the rolling speed is 550 m / min, and the finishing oil prepared in 1) is used in the finishing rolling treatment.

[0162] D. Cutting: Process at a speed of 300 m / min.

[0163] F. Precision cutting, corona treatment, corona power of 60KW, speed of 150m / min, corona treatment once, to obtain aluminum foil, the roughness of the aluminum foil is 0.15μm.

[0164] 3) Coating of positive electrode aqueous ceramic materials

[0165] Boehmite (Zhongchao Co., Ltd., ZCM-01) was weighed and evenly dispersed in deionized water to prepare a water-based ceramic slurry. The water-based ceramic slurry was coated using a gravure coating device at a coating speed of 150 m / min and dried. The coating amount was 10.0 g / m based on the mass of boehmite. 2 .

[0166] Examples 2 to 6 and Comparative Examples 1 to 5

[0167] The aluminum foils of Examples 2-6 and Comparative Examples 1-5 were prepared using methods similar to those of Example 1, with the coating amounts being similar. However, the mass contents of fatty alcohols and fatty acid esters in the refining oil and the corona treatment parameters were adjusted. The viscosity of the refining oil and the quality control of the colloid were similar to those of Example 1. Specific preparation parameters are detailed in Table 1.

[0168] 2. Calculation of aluminum foil leakage ratio

[0169] The total number of aluminum foils to be coated with ceramic slurry is N, the number of aluminum foils that are not coated after being coated with ceramic slurry is n, and the percentage of aluminum foil not coated (%) = n / N×100%.

[0170] The preparation parameters and the ratio of the missing coating of Examples 1 to 6 and Comparative Examples 1 to 5 are shown in Table 1 below:

[0171] Table 1

[0172]

[0173] It can be seen from Examples 1 to 6 and Comparative Examples 1 to 5 that the rolling oil contains 1.0% to 3.0% by mass of fatty alcohol and 6.7% to 10.0% by mass of fatty acid ester, indicating that the rolling oil helps to improve the adhesion performance of the aqueous positive electrode slurry and can significantly reduce the proportion of aluminum foil coating leaks.

[0174] Figure 1 A comparison of the aluminum foils coated with the water-based ceramic material in Example 1 and Comparative Example 1 shows that the aluminum foil in Example 1 is completely coated with the ceramic material, while the aluminum foil in Comparative Example 1 has obvious areas of missing coating. This indicates that the rolling oil and preparation process in the examples can help improve the problem of missing coating of the ceramic material.

[0175] Examples 2 and 3 show that even with a rolling oil containing 1.7% by weight of fatty alcohol and 6.7% by weight of fatty acid ester, and with only one corona treatment or no corona treatment, the aluminum foil still exhibits good wettability and significantly improves the percentage of positive electrode slurry leaks. This indicates that rolling oil can help reduce energy consumption during aluminum foil rolling and improve production capacity.

[0176] It can be seen from Examples 1 and 2 that under the treatment conditions of a maximum corona speed of 150 m / min or 260 m / min, the rolling oil prepared using the examples of the present application can significantly improve the leakage ratio of the positive electrode slurry, which helps to improve the production capacity of aluminum foil.

[0177] Comparative Example 1 shows that when the fatty alcohol content in the rolling oil is less than 1% by weight and the fatty acid ester content is greater than 10% by weight, the aluminum foil has a 100% non-coating rate without corona treatment. In Comparative Example 4, where corona treatment was performed twice, the non-coating rate was reduced but still as high as 10%.

[0178] It can be seen from Comparative Examples 2 and 3 that, under the condition that the rolling oil does not contain fatty acids, increasing the mass content of fatty acid esters cannot improve the wettability of aluminum foil and cannot improve the leakage coating ratio of the positive electrode slurry.

[0179] It can be seen from Comparative Examples 3 and 5 that, under the condition that the rolling oil does not contain fatty acids, increasing the number of corona treatments can improve the non-coating ratio of the positive electrode slurry, but the non-coating ratio is still as high as 20%.

[0180] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A positive electrode current collector rolling oil, characterized in that: include: Fatty alcohol compounds, fatty acid ester compounds and base oil; wherein, based on the total mass of the rolling oil, the mass content of the fatty alcohol compounds is 1.0% to 3.0%, and the mass content of the fatty acid ester compounds is 6.5% to 10.0%.

2. The positive electrode current collector rolling oil according to claim 1, characterized in that Based on the total mass of the rolling oil, the mass content of the fatty alcohol compound is 1.0% to 2.0%.

3. The positive electrode current collector rolling oil according to claim 1 or 2, characterized in that: Based on the total mass of the rolling oil, the mass content of the fatty acid ester compound is 6.0% to 9.0%.

4. The positive electrode current collector rolling oil according to any one of claims 1 to 3, characterized in that Based on the total mass of the rolling oil, the mass content of the fatty acid ester compound is 6.5% to 8.0%.

5. The positive electrode current collector rolling oil according to any one of claims 1 to 4, characterized in that The viscosity of the rolling oil is less than or equal to 2.1 mm 2 / s.

6. The positive electrode current collector rolling oil according to any one of claims 1 to 5, characterized in that The mass content of gum in the rolling oil is less than or equal to 1000 mg / 100 ml.

7. The positive electrode current collector rolling oil according to any one of claims 1 to 6, characterized in that The base oil includes at least one of 80# base oil, 95# base oil, 90# base oil, and 100# base oil.

8. The positive electrode current collector rolling oil according to any one of claims 1 to 7, characterized in that The positive electrode current collector is selected from aluminum current collector.

9. The positive electrode current collector rolling oil according to any one of claims 1 to 8, characterized in that The fatty alcohol compound has a C10-C14 aliphatic hydrocarbon group, and / or In the fatty acid ester compound, the fatty acid end and the fatty alcohol end thereof independently have a C6-C10 aliphatic hydrocarbon group.

10. A method for preparing a positive electrode current collector, characterized in that: The following steps are involved: The positive electrode current collector blank is subjected to rough rolling and intermediate rolling to obtain an intermediate current collector; The intermediate current collector is finish-rolled using positive current collector rolling oil and cut to obtain the positive current collector; the positive current collector rolling oil includes: fatty alcohol compounds, fatty acid ester compounds and base oil; wherein, based on the total mass of the rolling oil, the mass content of the fatty alcohol compounds is 1.0% to 3.0%, and the mass content of the fatty acid ester compounds is 6.5% to 10.0%.

11. The preparation method according to claim 10, characterized in that: The method further comprises corona treatment.

12. The preparation method according to claim 11, characterized in that The corona treatment is performed after the slitting process.

13. The preparation method according to claim 11 or 12, characterized in that: The corona treatment satisfies at least one of the following conditions: (1) Corona power is 30KW~60KW; (2) A corona speed of 100 m / min to 260 m / min; and / or (3) The number of corona discharges does not exceed 2 times.

14. The preparation method according to any one of claims 10 to 13, characterized in that In the finishing rolling process, the roller roughness of the finishing pass is 0.08 μm to 0.15 μm.

15. A positive electrode current collector, characterized in that: Prepared by the method according to any one of claims 10 to 14.

16. The positive electrode current collector according to claim 15, characterized in that: The roughness of the positive electrode current collector is 0.1 μm to 0.3 μm.

17. A secondary battery, characterized in that: Comprising the positive electrode current collector according to claim 15 or 16.

18. The secondary battery according to claim 17, wherein: The positive electrode active material of the secondary battery includes a lithium-containing phosphate having an olivine structure.

19. An electrical device, characterized in that: The secondary battery according to claim 17 or 18 is included.

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