Positive electrode sheet, method for manufacturing the same, battery, and power storage device

Abstract

The application discloses a positive electrode sheet, a preparation method thereof, a battery and a power utilization device. The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer. The positive electrode current collector comprises not less than 98% by weight of Al, 0.1%-1.9% by weight of Fe and 0.1%-1.9% by weight of Si. The positive electrode active material layer is formed on at least one side of the positive electrode current collector, and the Dv50 of positive electrode material particles in the positive electrode active material layer is not greater than 2 microns. Thus, by adopting the positive electrode current collector with high elongation and / or high tensile strength, the probability of the positive electrode current collector being broken during the rolling process of the positive electrode sheet can be reduced, and the yield of the positive electrode sheet is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a positive electrode sheet and its preparation method, a battery, and an electrical device. Background Technology

[0002] Lithium-ion batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power plants, as well as in many fields such as power tools, electric bicycles, electric motorcycles, electric cars, military equipment, and aerospace, due to their advantages such as high energy density, excellent cycle performance, environmental friendliness and no memory effect.

[0003] Lithium-ion batteries include a positive electrode sheet, which is formed by coating a positive electrode slurry onto a current collector. In the prior art, after the positive electrode slurry is coated onto the positive electrode current collector, the current collector is prone to breakage during the rolling process of the positive electrode sheet. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide a positive electrode sheet that significantly improves the situation of strip breakage during the rolling process and has a high yield.

[0005] To achieve the above objectives, this application provides a positive electrode sheet and its preparation method, a battery, and an electrical device.

[0006] To achieve the above objectives, a first aspect of this application provides a positive electrode sheet comprising a positive current collector and a positive active material layer, wherein the positive current collector comprises not less than 98 wt% Al, 0.1 wt%-1.9 wt% Fe and 0.1 wt%-1.9 wt% Si, and the positive active material layer is formed on at least one side of the positive current collector, wherein the Dv50 of the positive electrode material particles in the positive active material layer is not greater than 2 μm.

[0007] Compared with the prior art, this application has at least the following beneficial effects: The positive electrode sheet of this application includes a positive current collector and a positive active material layer, wherein the Dv50 of the positive material particles in the positive active material layer is not higher than 2μm, thereby making the positive active material layer have a high elongation. The positive current collector used in this application includes not less than 98 wt% Al, 0.1 wt%-1.9 wt% Fe and 0.1 wt%-1.9 wt% Si. This positive current collector has high strength and / or elongation, which can significantly reduce the probability of the positive current collector breaking during the rolling process of the positive electrode sheet, thereby improving the yield of the positive electrode sheet.

[0008] In any embodiment of this application, the positive electrode current collector comprises not less than 98 wt% Al, 0.2 wt%-1.9 wt% Fe, and 0.1 wt%-1.8 wt% Si. This reduces the probability of strip breakage during the rolling process of the positive electrode sheet, thereby improving the yield of the positive electrode sheet.

[0009] In any embodiment of this application, the positive electrode current collector comprises 98 wt%-99.5 wt% Al, 0.3 wt%-1 wt% Fe, and 0.1 wt%-1 wt% Si. This reduces the probability of strip breakage during the rolling process of the positive electrode sheet, thereby improving the yield of the positive electrode sheet.

[0010] In any embodiment of this application, before the positive electrode sheet undergoes rolling processing, the elongation of the positive current collector is 4.5%-8% and / or the tensile strength of the positive current collector is 215Gpa-250Gpa. This reduces the probability of strip breakage during the rolling process of the positive electrode sheet and improves the yield of the positive electrode sheet.

[0011] In any embodiment of this application, the thickness of the positive current collector is 10μm-18μm. This reduces the probability of strip breakage during the rolling process of the positive electrode sheet, thereby improving the yield of the positive electrode sheet.

[0012] In any embodiment of this application, the conductivity of the positive electrode current collector is not less than 20 S / m. This improves the kinetic performance of the secondary battery.

[0013] In any embodiment of this application, the surface roughness of the positive electrode current collector is 0.2 μm-0.4 μm. This improves the adhesion between the positive electrode current collector and the positive electrode active material layer.

[0014] In any embodiment of this application, the compaction density of the positive electrode active material layer is 2.0 g / cm³. 3 -2.7g / cm 3 This can improve the elongation of the positive electrode active material layer.

[0015] In any embodiment of this application, the Dv50 of the positive electrode material particles in the positive electrode active material layer is 0.3 μm-2 μm. This improves the elongation of the positive electrode active material layer.

[0016] In any embodiment of this application, the Dv90 / Dv50 of the cathode material particles is 2-5. This improves the elongation of the cathode active material layer.

[0017] In any embodiment of this application, the cathode material particles comprise one or more of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds. In any embodiment of this application, the lithium-containing phosphate comprises LiMPO4, and M comprises Mn and non-Mn elements. The non-Mn elements comprise one or two of a first doping element and a second doping element. The first doping element is manganese doping, and the second doping element is phosphorus doping. The first doping element comprises one or more of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge, or the first doping element comprises at least two of Fe, Ti, V, Ni, Co, and Mg, and the second doping element comprises one or more of B, S, Si, and N. Thus, by doping the above-mentioned metal elements at manganese and / or phosphorus sites, significantly improved rate performance can be obtained, while significantly reducing the dissolution of Mn and Mn-site doping elements, resulting in significantly improved cycle performance and / or high-temperature stability. Furthermore, the specific capacity and compaction density of the material can also be improved.

[0018] A second aspect of this application provides a method for preparing a positive electrode sheet, comprising:

[0019] A positive electrode current collector is provided, wherein the positive electrode current collector comprises not less than 98 wt% Al, 0.1 wt%-1.9 wt% Fe and 0.1 wt%-1.9 wt% Si;

[0020] A positive electrode active material layer is formed on at least one side of the positive electrode current collector, wherein the Dv50 of the positive electrode material particles in the positive electrode active material layer is not greater than 2 μm. The positive electrode active material layer is then rolled to obtain a positive electrode sheet. Thus, by forming a positive electrode active material layer on the surface of the positive electrode current collector, wherein the Dv50 of the positive electrode material particles in the positive electrode active material layer is not higher than 2 μm, the positive electrode active material layer has a high elongation. The positive electrode current collector used in this application comprises not less than 98 wt% Al, 0.1 wt%-1.9 wt% Fe, and 0.1 wt%-1.9 wt% Si. This positive electrode current collector has high tensile strength and / or elongation, thereby reducing the probability of strip breakage of the positive electrode current collector during the rolling process of the positive electrode sheet and improving the yield of the positive electrode sheet.

[0021] In any embodiment of this application, before the rolling process, the elongation of the positive current collector is 4.5%-8% and / or the tensile strength of the positive current collector is 215Gpa-250Gpa. This reduces the probability of strip breakage during the rolling process and improves the yield of the positive electrode sheet.

[0022] A third aspect of this application provides a battery comprising a positive electrode sheet according to the first aspect of this application or a positive electrode sheet obtained using the method of the second aspect of this application.

[0023] A fourth aspect of this application provides an electrical device comprising a battery according to a third aspect of this application, the battery being used to provide electrical energy.

[0024] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0025] To more clearly illustrate the technical solution of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without any creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of a battery according to one embodiment of this application.

[0027] Figure 2 This is a schematic diagram of the structure of a battery module according to one embodiment of this application.

[0028] Figure 3 This is a schematic diagram of the structure of a battery pack according to one embodiment of this application.

[0029] Figure 4 yes Figure 3 The exploded diagram.

[0030] Figure 5 This is a schematic diagram of one embodiment of an electrical device in which a battery is used as a power source.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1: Secondary battery; 2: Battery module; 3: Battery pack; 4: Upper casing; 5: Lower casing. Detailed Implementation

[0033] The present application will be further described below with reference to specific embodiments. It should be understood that these specific embodiments are for illustrative purposes only and are not intended to limit the scope of the present application.

[0034] For the sake of brevity, this article only discloses some specific numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0035] In this description, unless otherwise stated, the term "or" is inclusive. That is, the phrase "A or (or) B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: 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).

[0036] In the description of this article, it should be noted that, unless otherwise stated, "above" and "below" include the number itself, and "several" in "one or more" means two or more.

[0037] Unless otherwise stated, the terms used in this application have their common meanings as commonly understood by those skilled in the art. Unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0038] One aspect of this application provides a positive electrode sheet comprising a positive current collector and a positive active material layer, wherein the positive current collector comprises not less than 98 wt% Al, 0.1 wt%-1.9 wt% Fe and 0.1 wt%-1.9 wt% Si, and the positive active material layer is formed on at least one side of the positive current collector, wherein the Dv50 of the positive electrode material particles in the positive active material layer is not greater than 2 μm.

[0039] It should be noted that "the positive electrode active material layer is formed on at least one side of the positive electrode current collector" should be understood as "the positive electrode active material layer is formed on one or both sides of the positive electrode current collector", and the positive electrode active material layer can directly contact the surface of the positive electrode current collector, which is called "direct contact"; or there may be other layers between the surface of the positive electrode current collector and the positive electrode active material layer, which is called "indirect contact".

[0040] Through extensive research, the inventors discovered that coating the positive electrode slurry onto the positive electrode current collector and then rolling it can increase the compaction density of the positive electrode active material layer, thereby increasing the energy density of the battery. However, when the Dv50 of the positive electrode material particles in the positive electrode active material layer is small (Dv50 not higher than 2μm), the positive electrode active material layer has a high elongation. During the rolling process, the high elongation of the positive electrode active material layer causes the positive electrode current collector to stretch significantly, leading to strip breakage. Therefore, the positive electrode current collector used in this application comprises not less than 98 wt% Al, 0.1 wt%-1.9 wt% Fe, and 0.1 wt%-1.9 wt% Si. This positive electrode current collector has high tensile strength and / or elongation, which can significantly reduce the probability of strip breakage of the positive electrode current collector during the rolling process of the positive electrode sheet, thereby improving the yield of the positive electrode sheet.

[0041] In some embodiments, the Dv50 of the cathode material particles in the cathode active material layer is 0.3μm-2μm, for example 0.4μm-2μm, 0.5μm-1.9μm, 0.6μm-1.8μm, 0.7μm-1.7μm, 0.8μm-1.6μm, 0.9μm-1.5μm, 1.0μm-1.4μm, 1.1μm-1.3μm, or 1.2μm-1.3μm. Therefore, cathode material particles of this size can effectively improve the elongation of the cathode active material layer.

[0042] In some embodiments, the Dv90 / Dv50 ratio of the positive electrode material particles in the positive electrode active material layer is 2-5, for example, a Dv90 to Dv50 ratio of 2-4.8, 2.2-4.8, 2.4-4.8, 2.5-4.6, 2.8-4.5, 3-4.5, 3.2-4.5, 3.5-4.5, 3.8-4.5, 4-4.5, or 4.2-4.5, etc. Specifically, the Dv90 to Dv50 ratio of the positive electrode material particles in the positive electrode active material layer reflects the particle size distribution of the positive electrode material particles. The positive electrode material particles with a Dv90 / Dv50 ratio that meet the requirements of this application have a narrow particle size distribution, indicating that most of the positive electrode material particles in the positive electrode active material layer of this application are small and similar in size.

[0043] In this application, Dv90 refers to the particle size corresponding to a cumulative volumetric distribution percentage of 90%, and Dv50 refers to the particle size corresponding to a cumulative volumetric distribution percentage of 50%. For example, the determination is performed using a laser particle size analyzer (e.g., Malvern Master Size 3000) in accordance with standard GB / T 19077-2016.

[0044] In some embodiments, the compaction density of the positive electrode active material layer is 2.0 g / cm³. 3 -2.7g / cm3 For example, 2.1 g / cm³ 3 -2.7g / cm 3 2.2g / cm 3 -2.6g / cm 3 2.3g / cm 3 -2.6g / cm 3 2.4g / cm 3 -2.6g / cm 3 2.6g / cm 3 -2.5g / cm 3 This increases the compaction density of the positive electrode active material layer, making the positive electrode current collector more prone to breakage during the rolling process. Consequently, a higher demand is placed on the elongation and / or tensile strength of the positive electrode current collector. This application utilizes a positive electrode current collector with high tensile strength and / or high elongation, thereby reducing the probability of strip breakage during the rolling process of the positive electrode sheet and improving the yield of the positive electrode sheet.

[0045] According to some embodiments, the test method for the compaction density of the positive electrode active material layer is as follows: the thickness of the positive electrode sheet is measured with a micrometer and recorded as h1 cm; the thickness of the positive electrode current collector is then measured with a micrometer and recorded as h2 cm; finally, the positive electrode sheet is cut using a punching machine, and the weight of a single-sided area of ​​the positive electrode sheet is measured and recorded as mg / cm². 2 The compaction density of the positive electrode active material layer is the compaction density (PD) of the positive electrode sheet, and the calculation formula is: PD = m / (h1-h2)g / cm 3 .

[0046] In some embodiments, the specific type of the positive electrode active material is not limited, and active materials known in the art that can be used for the positive electrode of secondary batteries can be used. Those skilled in the art can select according to actual needs.

[0047] As an example, the positive electrode active material may include, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, one or more of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their modified compounds. All of these materials are commercially available.

[0048] The modified compounds for the above materials can be used to modify the materials by doping and / or by surface coating.

[0049] As an example, the lithium-containing phosphate includes LiMPO4, and M includes Mn and non-Mn elements. The non-Mn element includes one or both of a first dopant and a second dopant. The first dopant is manganese doping, and the second dopant is phosphorus doping. The first dopant includes one or more of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge; or the first dopant includes at least two of Fe, Ti, V, Ni, Co, and Mg, and the second dopant includes one or more of B, S, Si, and N. Therefore, by doping the above-mentioned metal elements at manganese and phosphorus sites, significantly improved rate performance can be obtained, while significantly reducing the dissolution of Mn and Mn-site dopant elements, resulting in significantly improved cycle performance and / or high-temperature stability. Furthermore, the specific capacity and compaction density of the material can also be improved.

[0050] The positive electrode active material layer may also optionally include binders, conductive agents, and other optional additives.

[0051] As an example, conductive agents may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, SuperP(SP), graphene, and carbon nanofibers.

[0052] As an example, the adhesive may include one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0053] In some embodiments, to reduce the probability of strip breakage during rolling of the positive electrode sheet, the positive electrode current collector composition used in this application includes not less than 98 wt% Al, 0.1 wt%-1.9 wt% Fe, and 0.1 wt%-1.9 wt% Si. For example, the Fe content is 0.1 wt%-1.8 wt%, 0.2 wt%-1.8 wt%, 0.3 wt%-1.7 wt%, 0.4 wt%-1.6 wt%, 0.5 wt%-1.5 wt%, 0.6 wt%-1.4 wt%, and 0.7 wt%-1.3 wt%. %, 0.8 wt%-1.2 wt%, 0.9 wt%-1.1 wt%, 0.9 wt%-1.0 wt%; Si content is 0.1 wt%-1.8 wt%, 0.2 wt%-1.8 wt%, 0.3 wt%-1.7 wt%, 0.4 wt%-1.6 wt%, 0.5 wt%-1.5 wt%, 0.6 wt%-1.4 wt%, 0.7 wt%-1.3 wt%, 0.8 wt%-1.2 wt%, 0.9 wt%-1.1 wt%, 0.9 wt%-1.0 wt%. In some other embodiments, the positive electrode current collector comprises not less than 98 wt% Al, 0.2 wt%-1.9 wt% Fe and 0.1 wt%-0.1.8 wt% Si. In some other embodiments, the positive current collector comprises 98 wt%-99.5 wt% Al, 0.3 wt%-1 wt% Fe, and 0.1 wt%-1 wt% Si. Compared to ordinary aluminum current collectors, the aluminum current collector of this application has higher strength and ductility.

[0054] Specifically, the elongation of the positive electrode current collector conforming to the composition of this application is 4.5%-8%, and the tensile strength is 215GPa-250GPa. For example, the elongation is 4.6%-8%, 4.8%-7.5%, 5%-8%, 5.1%-8%, 5.2%-7.8%, 5.5%-7.7%, 5.6%-7.7%, 5.8%-7.5%, 6%-7.5%, 6.2%-7.3%, 6.5%-7%, 6.5%-6.8%, etc.; and the tensile strength is 215GPa-250GPa, 217GPa-250GPa, 22... 0GPa-250GPa, 220GPa-248GPa, 222GPa-248GPa, 224GPa-248GPa, 225GPa-248GPa, 226GPa-248GPa, 230GPa-248GPa, 234GPa-248GPa, 236GPa-248GPa, 238GPa-248GPa, 240GPa-248GPa, 244GPa-248GPa, 246GPa-248GPa, etc., thereby reducing the probability of positive electrode sheet roll breakage.

[0055] In some embodiments, the thickness of the positive current collector is 10μm-18μm. For example, the thickness of the positive current collector used in this application is 11μm-18μm, 12μm-17μm, 13μm-16μm, or 14μm-15μm. Therefore, the positive current collector with this thickness has excellent elongation and tensile strength, thereby reducing the probability of strip breakage during the rolling process of the positive electrode sheet and improving the yield of the positive electrode sheet.

[0056] In some embodiments, the conductivity of the positive current collector is not less than 20 S / m, which facilitates electron conduction and thereby improves the dynamic performance of the battery.

[0057] According to some embodiments, the conductivity test method of the positive current collector is as follows: the conductivity of the positive current collector is tested using an eddy current conductivity meter. The positive current collector is placed on the test box of the conductivity meter, the instrument is turned on, the test line is placed on the positive current collector, the test is started, and the test data is read after the value stabilizes. This is the conductivity test result of the positive current collector.

[0058] In some embodiments, to improve the bonding strength between the positive electrode current collector and the positive electrode active material layer, this application uses a positive electrode current collector with a surface roughness of 0.2 μm-0.4 μm, for example, a surface roughness of 0.2 μm-0.3 μm or 0.3 μm-0.4 μm. This improves the adhesion between the positive electrode current collector and the positive electrode active material layer.

[0059] According to some embodiments, the surface roughness test method for positive current collector is as follows: The surface roughness of the positive current collector is tested using a Beijing Times Zhongyi TRL400 stylus. During the measurement, the stylus is brought into contact with the surface of the positive current collector to be measured. When the stylus moves along the contour of the surface to be measured under the drive of the driver, due to the unevenness of the surface contour, the stylus makes vertical undulating motion in the direction perpendicular to the contour of the surface to be measured. This motion is converted into an electrical signal by the sensor, and after amplification and processing, the surface contour evaluation parameter value can be displayed on the display, which is the test result of the surface roughness of the positive current collector.

[0060] A second aspect of this application provides a method for preparing a positive electrode sheet, comprising:

[0061] A positive electrode current collector is provided, wherein the positive electrode current collector comprises not less than 98 wt% Al, 0.1 wt%-1.9 wt% Fe and 0.1 wt%-1.9 wt% Si;

[0062] A positive electrode active material layer is formed on at least one side of the positive electrode current collector, wherein the Dv50 of the positive electrode material particles in the positive electrode active material layer is not greater than 2μm, and then the positive electrode active material layer is rolled to obtain a positive electrode sheet.

[0063] Therefore, by forming a positive electrode active material layer on the surface of the positive electrode current collector, wherein the Dv50 of the positive electrode material particles in the positive electrode active material layer is not higher than 2μm, the positive electrode active material layer has a high elongation. The positive electrode current collector used in this application includes not less than 98 wt% Al, 0.1 wt%-1.9 wt% Fe and 0.1 wt%-1.9 wt% Si. This positive electrode current collector has high tensile strength and / or elongation, thereby reducing the probability of strip breakage of the positive electrode current collector during the rolling process of the positive electrode sheet and improving the yield of the positive electrode sheet.

[0064] In some embodiments, the positive electrode active material can be mixed with a conductive agent, a binder and a solvent to form a slurry, and then the slurry is rolled onto one or both sides of the positive electrode current collector. After drying, a positive electrode active material layer is formed on one or both sides of the positive electrode current collector. Then, the positive electrode active material layer is rolled under a pressure of 30 tons to obtain a positive electrode sheet.

[0065] In some embodiments, before the rolling process, the elongation of the positive current collector is 4.5%-8% and / or the tensile strength of the positive current collector is 215Gpa-250Gpa. This reduces the probability of strip breakage during the rolling process and improves the yield of the positive electrode.

[0066] It should be noted that the composition, conductivity, thickness, roughness, and compaction density of the positive electrode current collector are the same as described above, and will not be repeated here.

[0067] A third aspect of this application provides a battery comprising a positive electrode sheet according to the first aspect of this application or a positive electrode sheet obtained using the method of the second aspect of this application.

[0068] [Negative electrode plate]

[0069] In a battery, the negative electrode typically includes a negative current collector and a negative active material layer disposed on the negative current collector, the negative active material layer comprising a negative active material.

[0070] The negative electrode current collector can be a conventional metal foil or a composite current collector (for example, a metal material can be disposed on a polymer substrate to form a composite current collector). As an example, the negative electrode current collector can be a copper foil.

[0071] The specific type of negative electrode active material is not limited; any active material known in the art that can be used for battery negative electrodes can be used, and those skilled in the art can select according to actual needs. As an example, the negative electrode active material may include, but is not limited to, one or more of artificial graphite, natural graphite, hard carbon, soft carbon, silicon-based materials, and tin-based materials. The silicon-based material may be selected from one or more of elemental silicon, silicon oxide compounds (e.g., silicon suboxide), silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from one or more of elemental tin, tin oxide compounds, and tin alloys. These materials are all commercially available.

[0072] In some embodiments, the negative electrode active material may include a silicon-based material in order to further improve the energy density of the battery.

[0073] The negative electrode active material layer may also optionally include binders, conductive agents, and other optional additives.

[0074] As an example, conductive agents may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0075] As an example, the adhesive may include one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0076] As an example, other optional additives may be thickeners and dispersants (such as sodium carboxymethyl cellulose CMC-Na) and PTC thermistor materials.

[0077] Electrolyte

[0078] The battery may include an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte may include an electrolyte salt and a solvent.

[0079] As an example, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0080] As an example, the solvent may include one or more of ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0081] In some embodiments, the electrolyte also includes additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and additives that improve battery low-temperature performance.

[0082] In some implementations, the battery can be a lithium-ion battery.

[0083] [Isolation membrane]

[0084] In some embodiments, the battery also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0085] In some embodiments, the material of the separator may include at least one selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may 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 may be the same or different, without particular limitation.

[0086] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0087] This application does not impose any particular limitation on the shape of the battery; it can be cylindrical, square, or any other arbitrary shape. Figure 1 This is a square-structured battery 1 used as an example.

[0088] In some embodiments, the battery may include an outer packaging. This outer packaging is used to encapsulate the positive electrode, the negative electrode, and the electrolyte.

[0089] In some embodiments, the outer packaging may include a shell and a cover. The shell may include a base plate and side plates attached to the base plate, the base plate and side plates enclosing a receiving cavity. The shell has an opening communicating with the receiving cavity, and the cover can be placed over the opening to close the receiving cavity.

[0090] The positive electrode, negative electrode, and separator can be formed into an electrode assembly through a winding or stacking process. The electrode assembly is encapsulated within the receiving cavity. The electrolyte can be a liquid electrolyte, which is immersed in the electrode assembly. The battery can contain one or more electrode assemblies, which can be adjusted according to requirements.

[0091] In some implementations, the outer casing of the battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell.

[0092] The outer packaging of the battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0093] In some implementations, batteries can be assembled into battery modules, and the number of batteries contained in a battery module can be multiple, with the specific number adjustable according to the application and capacity of the battery module.

[0094] Figure 2 This is battery module 2 as an example. (See reference...) Figure 2 In battery module 2, multiple batteries 1 can be arranged sequentially along the length of battery module 2. Of course, they can also be arranged in any other way. Furthermore, these multiple batteries 1 can be fixed in place using fasteners.

[0095] The battery module 2 may also include a housing with a receiving space in which multiple batteries 1 are housed. In some embodiments, the battery modules may also be assembled into a battery pack, the number of battery modules contained in the battery pack being adjustable according to the application and capacity of the battery pack.

[0096] Figure 3 and 4 This is battery pack 3 as an example. (See reference...) Figure 3 and 4 The battery pack 3 may include a battery box and multiple battery modules 2 disposed within the battery box. The battery box includes an upper body 4 and a lower body 5, with the upper body 4 covering the lower body 5 to form a closed space for accommodating the battery modules 2. The multiple battery modules 2 can be arranged in any manner within the battery box.

[0097] [Electrical appliances]

[0098] This application also provides an electrical device, which includes the battery described above. The battery can serve as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device may be, but is not limited to, mobile devices (e.g., mobile phones, laptops), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks), electric trains, ships and satellites, and energy storage systems.

[0099] The electrical device can select batteries according to its usage requirements.

[0100] Figure 5 This is an example of an electrical device. The device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0101] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use batteries as their power source.

[0102] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, the following will provide a more detailed description in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0103] Example 1

[0104] Methods for preparing electrode sheets:

[0105] (1) The positive electrode material LiMn 0.7 Fe 0.3 PO4 (particle Dv50 of 2μm), conductive agent carbon black (Super P), and binder polyvinylidene fluoride (PVDF) were mixed evenly in an appropriate amount of solvent N-methylpyrrolidone (NMP) at a mass ratio of 96.2:2.7:1.1 to obtain a positive electrode slurry with a solid content of 58%-62%.

[0106] (2) The positive electrode slurry is coated on both sides of the positive electrode current collector (composition includes 99.33% by weight Al, 0.47% by weight Fe and 0.2% by weight Si, with a thickness of 15 μm and a surface roughness of 0.2 μm), and then dried to obtain a dried electrode sheet.

[0107] The preparation methods of the electrodes in Examples 2-29 and the comparative examples are similar to those of the electrodes in Example 1, with the differences detailed in Table 1.

[0108] Table 1

[0109]

[0110]

[0111] Characterize the breakage of the drying electrode sheet under roller pressure:

[0112] Ten groups of dried electrode sheets obtained from Examples 1-29 and the comparative example were rolled under a pressure of 30T to obtain positive electrode sheets. The breakage of the strip during the rolling process and the compaction density of the obtained positive electrode sheets are shown in Table 2.

[0113] Table 2

[0114]

[0115]

[0116] As shown in Table 1, the positive electrode current collectors of Examples 1-29 consist of 98wt%-99.8wt% Al, 0.1wt%-1.9wt% Fe, and 0.1wt%-1.9wt% Al, with an elongation of not less than 4.5% and a tensile strength of not less than 215MPa before rolling. In the comparative example, the positive electrode current collector consists of 99.9wt% Al, 0.05wt% Fe, and 0.05wt% Si, with an elongation of 4% and a tensile strength of 200MPa before rolling. As shown in Table 2, the positive electrode sheets of Examples 1-29 did not experience strip breakage during the rolling process, while the positive electrode sheets of the comparative example experienced strip breakage during the rolling process. This indicates that using the positive electrode current collector of this application can significantly reduce the probability of strip breakage during the rolling process of the positive electrode sheet, thereby improving the yield of the positive electrode sheet.

[0117] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0118] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A positive electrode plate, characterized in that, include: The positive electrode current collector comprises not less than 98 wt% Al, 0.1 wt%-1.9 wt% Fe and 0.1 wt%-1.9 wt% Si; A positive electrode active material layer is formed on at least one side of the positive electrode current collector, wherein the Dv50 of the positive electrode material particles in the positive electrode active material layer is not greater than 2 μm.

2. The positive electrode sheet according to claim 1, characterized in that, The positive electrode current collector comprises not less than 98% by weight of Al, 0.2% to 1.9% by weight of Fe, and 0.1% to 1.8% by weight of Si.

3. The positive electrode sheet according to claim 1 or 2, characterized in that, The positive electrode current collector comprises 98.0-99.5% by weight Al, 0.3%-1% by weight Fe, and 0.1%-1% by weight Si.

4. The positive electrode sheet according to claim 1, characterized in that, Before the positive electrode sheet is rolled, the elongation of the positive current collector is 4.5%-8% and / or the tensile strength of the positive current collector is 215Gpa-250Gpa.

5. The positive electrode sheet according to claim 1, characterized in that, The thickness of the positive electrode current collector is 10μm-18μm.

6. The positive electrode sheet according to claim 1, characterized in that, The conductivity of the positive current collector is not less than 20 S / m.

7. The positive electrode sheet according to claim 1, characterized in that, The surface roughness of the positive electrode current collector is 0.2μm-0.4μm.

8. The positive electrode sheet according to claim 1, characterized in that, The compaction density of the positive electrode active material layer is 2.0 g / cm³. 3 -2.7g / cm 3 .

9. The positive electrode sheet according to claim 1, characterized in that, The Dv50 of the positive electrode material particles in the positive electrode active material layer is 0.3μm-2μm.

10. The positive electrode sheet according to claim 9, characterized in that, The Dv90 / Dv50 of the cathode material particles is 2-5.

11. The positive electrode sheet according to claim 10, characterized in that, The cathode material particles include one or more of lithium transition metal oxides, lithium phosphates, and their respective modified compounds.

12. The positive electrode sheet according to claim 11, characterized in that, The lithium-containing phosphate includes LiMPO4, and M includes Mn and non-Mn elements. The non-Mn elements include one or both of a first doping element and a second doping element. The first doping element is manganese site doping, and the second doping element is phosphorus site doping. The first doping element includes one or more of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge. Alternatively, the first doping element includes at least two of Fe, Ti, V, Ni, Co, and Mg, and the second doping element includes one or more of B, S, Si, and N.

13. A method for preparing a positive electrode sheet, characterized in that, include: A positive electrode current collector is provided, wherein the positive electrode current collector comprises not less than 98 wt% Al, 0.1 wt%-1.9 wt% Fe and 0.1 wt%-1.9 wt% Si; A positive electrode active material layer is formed on at least one side of the positive electrode current collector, wherein the Dv50 of the positive electrode material particles in the positive electrode active material layer is not greater than 2μm, and then the positive electrode active material layer is rolled to obtain a positive electrode sheet.

14. The method according to claim 13, characterized in that, Before the rolling process, the elongation of the positive current collector is 4.5%-8% and / or the tensile strength of the positive current collector is 215Gpa-250Gpa.

15. A battery, characterized in that, The battery comprises a positive electrode sheet according to any one of claims 1-12 or a positive electrode sheet obtained by the method according to claim 13 or 14.

16. An electrical appliance, characterized in that, The electrical device includes the battery of claim 15, the battery being used to provide electrical energy.

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