A battery, a preparation method thereof, and an electric device

Abstract

This invention provides a positive electrode sheet, a battery, a method for preparing the same, and an electrical device thereof. The positive electrode sheet includes a positive current collector and a positive active layer covering at least one side of the current collector. The positive active layer includes spaced-apart first protrusions, with a first recess between adjacent first protrusions. The first protrusions are fitted into second recesses, wherein the interval between adjacent first protrusions is R1. The thickness of the positive active layer is d, and the positive active layer includes a positive active material. The D50, D10, and D90 of the positive active material satisfy R1 and d as follows: 0.2d < R1(0.8D50 + 0.1D10 + 0.1D90) < 0.6d. The positive electrode sheet provided by this invention can reduce impedance with increased thickness, broadening the application scenarios of the battery.

Description

Technical Field

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

[0002] Driven by market demand, the demand for high-performance lithium-ion batteries continues to increase. Common positive electrode active materials for lithium-ion batteries include phosphate cathode materials such as lithium iron phosphate, lithium manganese iron phosphate, and lithium vanadium phosphate.

[0003] Currently, thicker electrodes are used in the design of rechargeable batteries to improve energy density. On the one hand, within the same battery system, thicker electrodes can accommodate more active material, increasing the overall energy storage density of the battery. Furthermore, the increased capacity of thicker electrodes also improves the battery's energy density. On the other hand, thicker electrodes reduce the number of electrode layers in the battery, thereby reducing the amount of auxiliary materials such as current collectors and separators used, simplifying the manufacturing process and lowering production costs. However, for phosphate-based cathode materials, increasing electrode thickness leads to higher impedance, which in turn affects the battery's charge and discharge efficiency, limiting its applications.

[0004] Therefore, how to reduce impedance and broaden the application scenarios of batteries while increasing electrode thickness has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention provides a positive electrode sheet that is specially designed to effectively reduce impedance and broaden the application scenarios of batteries.

[0006] This invention provides a battery in which, with increased electrode thickness, the positive and negative electrodes are specially designed to interlock, effectively reducing impedance and broadening the battery's application scenarios.

[0007] The present invention also provides a method for preparing a battery, which is simple to operate and can produce a battery with the aforementioned low impedance.

[0008] The present invention also provides an electrical device, which includes the above-mentioned battery or battery pack and has good performance.

[0009] The present invention provides a positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive active layer covering at least one side of the positive current collector, the positive active layer comprising spaced-apart first protrusions, a first recess between adjacent first protrusions, the first protrusions being fitted into a second recess, wherein the interval between adjacent first protrusions is R1.

[0010] The thickness of the positive electrode active layer is d, and the positive electrode active layer includes a positive electrode active material. The D50, D10, D90 of the positive electrode active material and R1, d satisfy: 0.2d < R1(0.8D50+0.1D10+0.1D90) < 0.6d.

[0011] For the positive electrode as described above, 0.35d < R1(0.8D50+0.1D10+0.1D90) < 0.45d.

[0012] As described above, the particle size distribution of the positive electrode active material satisfies: 0.15μm < D10 < 0.3μm;

[0013] And / or, 0.4μm < D50 < 0.6μm;

[0014] And / or, 2μm < D90 < 5μm.

[0015] For the positive electrode as described above, d≤200μm.

[0016] In another aspect, the present invention provides a battery comprising the above-described positive electrode.

[0017] The battery as described above further includes a negative electrode sheet, which includes a negative current collector and a negative active layer covering at least one side of the negative current collector; the negative active layer includes second protrusions spaced apart, with a second recess between two adjacent second protrusions, and the second protrusions are fitted into the first recess; the width of the second recess is R3; the D50, D10, D90 of the positive active material and R3, d satisfy: 0.2d < R3(0.8D50+0.1D10+0.1D90) < 0.6d;

[0018] The depth of the second pit is R2, which satisfies: d-(4d2-R12)0.5 / 2≤R2<0.6d.

[0019] For the battery as described above, 0.35d < R3(0.8D50+0.4D10+0.4D90) < 0.45d.

[0020] For the battery as described above, 0.8 ≤ R1 / R3 ≤ 1.2.

[0021] For the battery as described above, 0.9 ≤ R1 / R3 ≤ 1.1.

[0022] In the battery described above, the negative electrode active layer comprises a negative electrode active material, and the particle size distribution of the negative electrode active material satisfies: 4.0 μm ≤ D10 ≤ 9.0 μm;

[0023] And / or, 9.0μm≤D50≤16.0μm;

[0024] And / or, 15.0μm≤D90≤26.0μm.

[0025] In another aspect, the present invention provides a method for preparing the battery as described above, comprising the following steps: injecting a slurry including a positive electrode active material into a positive electrode mold having a first protrusion and a first pit, then laying a positive electrode current collector on the surface of the positive electrode mold, and baking and compacting to obtain a positive electrode sheet;

[0026] A slurry containing a negative electrode active material is injected into a negative electrode mold having a second protrusion and a second pit. Then, a negative electrode current collector is laid on the surface of the negative electrode mold, and the negative electrode sheet is obtained by baking and compaction.

[0027] The positive electrode, the separator, and the negative electrode are stacked together, with the first protrusion fitted into the second recess and the second protrusion fitted into the first recess, to obtain a battery.

[0028] In another aspect, the present invention provides an electrical device comprising a battery as described above or a battery pack as described above.

[0029] The positive electrode sheet provided by this invention optimizes the microstructure of the electrode material by optimizing the matching of particle size parameters and structural parameters. This optimization can further improve the conductivity and ionic conductivity of the material and further reduce the overall impedance of the battery.

[0030] The battery provided by this invention can significantly reduce impedance and improve battery performance in a thick electrode system. On one hand, the battery provided by this invention, through the interlocking concave-convex structure in the positive and negative electrodes, can increase the actual contact area between the positive and negative electrodes, improve the transport efficiency of ions and electrons between the electrodes, and reduce the internal resistance of the battery. Attached Figure Description

[0031] Figure 1 This is a partial schematic diagram of a battery in a specific embodiment of the present invention;

[0032] Figure 2 This is a partial schematic diagram of the battery in another specific embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram illustrating the preparation of the positive electrode sheet in another specific embodiment of the present invention.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1-Positive electrode sheet; 11-Positive current collector; 12-Positive active layer; 3-Negative electrode sheet; 31-Negative current collector; 32-Negative active layer; 4-Positive electrode mold; A-First protrusion; B-Second protrusion; a-First recess; b-Second recess. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0037] In thick electrode systems, ions need to traverse a thicker layer of active material to reach the reaction interface. This longer transport path increases the time and distance of ion diffusion, resulting in higher ion transport impedance. Furthermore, during the fabrication of thick electrodes, uneven material distribution may occur, leading to decreased conductivity and ion transport capacity in localized areas, thus increasing impedance.

[0038] The present invention provides a positive electrode sheet, comprising a positive current collector and a positive active layer covering at least one side of the positive current collector. The positive active layer includes first protrusions spaced apart, with a first recess between two adjacent first protrusions, and the first protrusions fitting into the second recess. The interval between adjacent first protrusions is R1.

[0039] The thickness of the positive electrode active layer is d. The positive electrode active layer includes positive electrode active material. The D50, D10, D90 of the positive electrode active material and R1, d satisfy: 0.2d < R1(0.8D50+0.1D10+0.1D90) < 0.6d.

[0040] It should be noted that the units of D50, D10, D90, R1, R2 and d should be consistent. For example, their units are all μm. Under the condition of consistent units, the pure values ​​of D50, D10, D90, R1, R2 and d should be calculated.

[0041] like Figure 2 As shown, in this invention, the interval R1 between adjacent first protrusions and the width R3 of the first protrusion refer to the maximum interval and the maximum width of the first protrusion in the cross-sectional pattern obtained by taking a cross section along the stacking direction of the positive current collector and the positive active layer. In some embodiments, when the periphery of the first protrusion contains protrusions or burrs, R1 can be understood as the average interval between adjacent first protrusions.

[0042] In this invention, the thickness of the positive electrode active layer can be the same as the thickness of the negative electrode active layer. The thickness of the positive electrode active layer refers to the maximum thickness of the positive electrode active layer, which is the shortest distance between the highest point of the first protrusion and the positive electrode current collector.

[0043] The D50 of a cathode active material refers to the most frequently occurring particle size. The D10 of a cathode active material represents the particle size corresponding to a cumulative particle size distribution percentage of 10%. The D90 of a cathode active material represents the particle size corresponding to a cumulative particle size distribution percentage of 90%.

[0044] This invention does not limit the testing method for the particle size distribution of the positive electrode active material. Common methods in the art can be used to determine the particle size distribution of the positive electrode active material. In one specific embodiment, an image recognition method is used for statistical analysis: First, the prepared electrode sheet is prepared, the cross-section is cut using an ion beam, the cross-section of the electrode sheet is photographed using HRSEM (high resolution scanning electron microscope), and the particles in the photographed image are counted and statistically analyzed using MIPAR image processing software to obtain particle size distribution data.

[0045] This invention does not limit the specific type of the positive electrode current collector, and can select a type commonly used in the art, such as aluminum foil, nickel foil, etc.; this invention also does not limit the specific type of the negative electrode current collector, and can select a type commonly used in the art. The material of the negative electrode current collector can be at least one of copper foil, nickel foam, and copper foam.

[0046] The positive electrode provided by this invention can significantly reduce impedance and improve battery performance. This is mainly achieved by optimizing the matching of particle size parameters and structural parameters, thereby optimizing the microstructure of the electrode. This optimization can further improve the ionic conductivity of the electrode and further reduce the overall impedance of the battery. At the same time, the electrode has strong physical stability within the aforementioned pit range, which can avoid the phenomenon of electrode collapse caused by excessive pit depth.

[0047] Furthermore, in one specific embodiment, 0.35d < R1(0.8D50+0.1D10+0.1D90) < 0.45d.

[0048] Tests have shown that when R1 meets the above-mentioned range, a uniform structure on the electrode surface can be achieved by controlling the spacing and width of the protrusions. This uniformity helps to evenly distribute the current density, reducing local overpotential and polarization phenomena. Simultaneously, optimized spacing and width can provide a more direct and efficient ion transport path, reducing ion diffusion resistance and improving the battery's rate performance. A well-designed structure also helps to improve ion transport efficiency within the electrode and reduce the battery's internal resistance.

[0049] Furthermore, in one specific embodiment, the particle size distribution of the positive electrode active material satisfies: 0.15μm < D10 < 0.3μm;

[0050] And / or, 0.4μm < D50 < 0.6μm;

[0051] And / or, 2μm < D90 < 5μm.

[0052] When the particle size distribution of the positive electrode active material satisfies the above range, it can not only shorten the diffusion path of ions inside the particles, further increase the ion transmission rate and reduce the diffusion impedance, but also the particle size distribution in the above range can provide more electrochemical active reaction sites, increase the contact area between the electrode and the electrolyte, and improve the electrochemical reaction rate and the rate performance of the battery.

[0053] Further, in a specific embodiment, d ≤ 200 μm.

[0054] When the thickness d of the positive electrode active layer satisfies the above range, it not only facilitates the arrangement of the first protruding portion and the first pit to reduce the process difficulty, but also enables the positive electrode material to exert more excellent rate characteristics by controlling the thickness d of the positive electrode active layer within the above range.

[0055] Exemplarily, d is any value selected from 200 μm, 190 μm, 180 μm, 170 μm, 160 μm, 150 μm, 140 μm, 130 μm, 120 μm, 110 μm, 100 μm and the like, or a range formed by two of the above values.

[0056] For positive electrode active materials, different types of positive electrode active materials bring different impedances when used in a thick electrode system. In a specific embodiment, the chemical formula of the positive electrode active material is LiFe x Mn 1-x PO₄, 0.2<x<0.4.

[0057] The above type of positive electrode active material is a lithium manganese iron phosphate-based active material. By adjusting the ratio of Fe and Mn, a balance can be achieved between energy density and cycle stability. A relatively high Mn content usually helps to increase the energy density, but may sacrifice part of the cycle stability, while a relatively low Mn content cannot achieve a significant energy density improvement. Selecting the range of 0.2<x<0.4 can increase the energy density without significantly reducing the cycle life.

[0058] Meanwhile, it has been found through tests that the above type of positive electrode active material has a more significant effect of reducing impedance, and can better improve the ion transmission efficiency.

[0059] In another aspect, the present invention provides a battery comprising the above positive electrode sheet.

[0060] The battery as described above, as shown in Figure 1 comprises a positive electrode sheet 1 and a negative electrode sheet 3. The positive electrode sheet 1 includes a positive electrode current collector 11 and a positive electrode active layer 12 covering at least one side of the positive electrode current collector 11. The negative electrode sheet 3 includes a negative electrode current collector 31 and a negative electrode active layer 32 covering at least one side of the negative electrode current collector 31;

[0061] The positive electrode active layer 12 includes first protrusions A spaced apart, and the negative electrode active layer 32 includes second protrusions B spaced apart. There is a first recess a between two adjacent first protrusions A and a second recess b between two adjacent second protrusions B. The first protrusions A are fitted into the second recess b, and the second protrusions B are fitted into the first recess a.

[0062] Among them, such as Figure 2 As shown, the interval between adjacent first protrusions A is R1, and the width of the first protrusion A is R3;

[0063] The thickness of the positive electrode active layer 12 is d. The positive electrode active layer 12 includes a positive electrode active material. The D50, D10, D90 of the positive electrode active material and R1, d satisfy the following conditions: 0.2d < R1(0.8D50+0.1D10+0.1D90) < 0.6d; 0.2d < R3(0.8D50+0.1D10+0.1D90) < 0.6d.

[0064] The depth of the second indentation is R2, which satisfies: d-(4d 2 -R1 2 ) 0.5 / 2≤R2<0.6d.

[0065] It should be noted that the units of D50, D10, D90, R1, R2 and d should be consistent. For example, their units are all μm. Under the condition of consistent units, the pure values ​​of D50, D10, D90, R1, R2 and d should be calculated.

[0066] In detail, at least one side of the positive current collector 11 is covered with a positive active layer, which includes spaced-apart first protrusions and a first recess between adjacent first protrusions. At least one side of the negative current collector is covered with a negative active layer, which includes spaced-apart second protrusions and a second recess between adjacent second protrusions. The first protrusions are fitted into the second recesses, and the second protrusions are fitted into the first recesses, thus achieving coupling between the negative and positive electrodes. This invention does not limit the morphology of the first protrusions, first recesses, second protrusions, and second recesses. It is understood that, in order for the first protrusions to fit into the second recesses and the second protrusions to fit into the first recesses, the cross-sectional shapes of the first protrusions and second recesses are identical in any given direction.

[0067] In one specific embodiment, the first protrusion, the second recess, the second protrusion, and the first recess are all cubes with the same shape.

[0068] like Figure 2As shown, in this invention, the interval R1 between adjacent first protrusions and the width R3 of the first protrusion refer to the maximum interval and the maximum width of the first protrusion in the cross-sectional pattern obtained by taking a cross section along the stacking direction of the positive current collector and the positive active layer. In some embodiments, when the periphery of the first protrusion contains protrusions or burrs, R1 can be understood as the average interval between adjacent first protrusions.

[0069] In this invention, the thickness of the positive electrode active layer can be the same as the thickness of the negative electrode active layer. The thickness of the positive electrode active layer refers to the maximum thickness of the positive electrode active layer, which is the shortest distance between the highest point of the first protrusion and the positive electrode current collector.

[0070] The battery provided by this invention can significantly reduce impedance and improve battery performance in a thick electrode system. On one hand, the battery provided by this invention, through the interlocking concave-convex structure in the positive and negative electrodes and by controlling the depth of the second pit to meet the aforementioned range, can increase the actual contact area between the positive and negative electrodes, improve the ion transport efficiency between the electrodes, and reduce the internal resistance of the battery. On the other hand, through optimized matching of particle size parameters and structural parameters, the microstructure of the electrodes can be optimized. This optimization can further improve the ionic conductivity of the electrodes, further reduce the overall impedance of the battery, and at the same time, the physical stability of the electrodes is strong within the aforementioned pit range, avoiding the phenomenon of electrode collapse due to excessive pit depth.

[0071] Furthermore, in one specific embodiment, 0.35d < R3(0.8D50+0.4D10+0.4D90) < 0.45d.

[0072] Tests showed that when R3 meets the above-mentioned range, a uniform structure on the electrode surface can be achieved by controlling the spacing and width of the protrusions. This uniformity helps to evenly distribute the current density, reducing local overpotential and polarization phenomena. Simultaneously, optimized spacing and width can provide a more direct and efficient ion transport path, reducing ion diffusion resistance and improving the battery's rate performance. A well-designed structure also helps to improve ion transport efficiency within the electrode and reduce the battery's internal resistance.

[0073] Furthermore, in one specific embodiment, 0.8 ≤ R1 / R3 ≤ 1.2; preferably: 0.9 ≤ R1 / R3 ≤ 1.1.

[0074] In detail, R1 / R3 includes, but is not limited to, a range consisting of 0.9, 0.91, 0.93, 0.95, 0.97, 0.99, 1.1, 1.2, or any two of these.

[0075] When ≤R1 / R3 meets the above range, on the one hand, it can fully guarantee the ion transport efficiency at the top and bottom of the protrusion, thereby reducing the internal resistance of the battery and improving the rate performance; on the other hand, the above range can ensure the uniformity of the electrode surface structure, promote the uniform distribution of current density, and reduce local overpotential and polarization phenomena.

[0076] As a crucial component of a battery, the separator's thickness significantly impacts the tightness of the bond between protrusions and recesses, especially when the positive electrode, separator, and negative electrode are stacked. In one specific embodiment, the separator thickness is 10 μm to 20 μm.

[0077] In detail, the thickness of the diaphragm includes, but is not limited to, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm or any two of these ranges.

[0078] When the separator is within the above range, it not only enables tight interlocking between the positive and negative electrode plates, but also reduces the path length of ions through the separator, further reducing ion transport impedance and improving the rate performance and overall efficiency of the battery.

[0079] This invention does not strictly limit the choice of separator material. It can be one of the separator materials commonly used in batteries, such as polypropylene separator (PP), polyethylene separator (PE), polypropylene / polyethylene double-layer composite membrane (PP / PE), polyimide electrospun separator (PI), polypropylene / polyethylene / polypropylene triple-layer composite membrane (PP / PE / PP), cellulose nonwoven separator, and separator with ceramic coating.

[0080] In one specific embodiment, the negative electrode active layer includes a negative electrode active material, and the particle size distribution of the negative electrode active material satisfies: 4.0μm≤D10≤9.0μm, 9.0μm≤D50≤16.0μm, and 15.0μm≤D90≤26.0μm.

[0081] Specifically, D10 includes, but is not limited to, a range of 4.0μm, 4.5μm, 5.0μm, 5.5μm, 6.0μm, 6.5μm, 7.0μm, 7.5μm, 8.0μm, 8.5μm, 9.0μm, or any combination thereof; D50 includes, but is not limited to, a range of 9.0μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, or any combination thereof; and D90 includes, but is not limited to, a range of 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, or any combination thereof.

[0082] This invention does not strictly limit the type of negative electrode active material. It can be at least one of the negative electrode active materials commonly used in batteries, such as graphite, hard carbon, soft carbon, mesophase carbon microspheres, silicon-based negative electrode materials (mainly including silicon suboxide and silicon-carbon negative electrodes), and tin-based negative electrode materials (mainly including tin and tin alloys).

[0083] When the particle size distribution of the negative electrode active material meets the above-mentioned range, a moderate particle size distribution (D50 in the range of 9.0-16.0 μm) is beneficial for the uniform coating of the slurry, reduces particle agglomeration, improves the uniformity and consistency of the electrode, and increases the compaction density of the electrode, thereby improving the energy density of the battery. Furthermore, a uniform particle size distribution avoids excessively high local current density or lithium dendrite growth, improving the safety and cycle stability of the battery. In another aspect, this invention provides a method for preparing the battery as described above, comprising the following steps: injecting a slurry including a positive electrode active material into a positive electrode mold having a first protrusion and a first recess; subsequently, laying a positive electrode current collector on the surface of the positive electrode mold; and baking and compacting to obtain a positive electrode sheet.

[0084] A slurry containing a negative electrode active material is injected into a negative electrode mold having a second protrusion and a second pit. Then, a negative electrode current collector is laid on the surface of the negative electrode mold, and the negative electrode sheet is obtained by baking and compaction.

[0085] A positive electrode, a separator, and a negative electrode are stacked together, with a first protrusion fitted into a second recess and a second protrusion fitted into a first recess, to obtain a battery.

[0086] The preparation method provided by this invention can be used to prepare the above-mentioned battery.

[0087] First, a slurry including a positive electrode active material is injected into a positive electrode mold having a first protrusion and a first recess. Then, a positive electrode current collector is laid on the surface of the positive electrode mold, and the mixture is baked and compacted to obtain a positive electrode sheet. The obtained positive electrode sheet includes a positive electrode current collector and a positive electrode active layer covering at least one side of the positive electrode current collector. The positive electrode active layer includes spaced-apart first protrusions, with a first recess between two adjacent first protrusions. Figure 3 The diagram shown is a schematic diagram of the preparation of a positive electrode sheet in a specific embodiment of the present invention. The mold 4 has a raised structure and a recessed structure, which constitute the first raised part and the first recessed part in the positive electrode sheet.

[0088] Subsequently, a slurry including a negative electrode active material is injected into a negative electrode mold having a second protrusion and a second pit. Then, a negative electrode current collector is laid on the surface of the negative electrode mold, and the negative electrode sheet is baked and compacted to obtain a negative electrode sheet. The obtained negative electrode sheet includes a negative electrode current collector and a negative electrode active layer covering at least one side of the negative electrode current collector. The negative electrode active layer includes first protrusions spaced apart, and a first pit is formed between two adjacent first protrusions.

[0089] A positive electrode, a separator, and a negative electrode are stacked together, with a first protrusion fitted into a second recess and a second protrusion fitted into a first recess, to obtain a battery.

[0090] It is understood that, in order to obtain the battery by the above preparation method, the particle size distribution relationship between the first protrusion and the first pit in the positive electrode mold and R1 and R3 in the second protrusion and the second pit in the negative electrode mold and the positive electrode active material should satisfy 0.2d < R1(0.8D50+0.1D10+0.1D90) < 0.6d; 0.2d < R3(0.8D50+0.1D10+0.1D90) < 0.6d.

[0091] In addition to the positive electrode active material, the slurry containing the negative electrode active material and the slurry containing the positive electrode active material may also include binders and conductive agents.

[0092] This invention does not strictly limit the specific types of binders and conductive agents, and can use substances commonly used in the art. For example, the conductive agent can be selected from at least one of carbon black, acetylene black, graphene, Ketjen black, and carbon fiber; the binder can be selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, ethylene oxide-containing polymers, polyvinylpyrrolidone, and polyurethane.

[0093] The preparation method provided by this invention is simple to operate, and the prepared battery has high energy density and low impedance, thus broadening the application scenarios of the battery.

[0094] In another aspect, the present invention provides an electrical device comprising a battery as described above or a battery pack as described above.

[0095] This invention does not limit the specific type of electrical equipment, and may include any device that requires a battery to power it, such as electric vehicles, mobile phones, smart home devices, robots, drones, e-cigarettes, and speakers.

[0096] The electrical equipment provided by the present invention includes the battery described above or the battery pack described above, and therefore has good performance.

[0097] The battery provided by the present invention will be described below through specific embodiments.

[0098] Example 1

[0099] The battery preparation method provided in this embodiment includes the following steps:

[0100] 1. A slurry including a positive electrode active material is injected into a positive electrode mold having a first protrusion and a first pit. Then, a positive electrode current collector is laid on the surface of the positive electrode mold, and the positive electrode sheet is baked and compacted to obtain a positive electrode sheet. The obtained positive electrode sheet includes a positive electrode current collector and a positive electrode active layer covering at least one side of the positive electrode current collector. The positive electrode active layer includes first protrusions arranged at intervals, and a first pit is formed between two adjacent first protrusions.

[0101] 2. A slurry including a negative electrode active material is injected into a negative electrode mold having a second protrusion and a second pit. Then, a negative electrode current collector is laid on the surface of the negative electrode mold, and the negative electrode sheet is baked and compacted to obtain a negative electrode sheet. The obtained negative electrode sheet includes a negative electrode current collector and a negative electrode active layer covering at least one side of the negative electrode current collector. The negative electrode active layer includes first protrusions arranged at intervals, and a first pit is formed between two adjacent first protrusions.

[0102] 3. The positive electrode, separator (14μm thick), and negative electrode are stacked together, with the first protrusion fitted into the second recess and the second protrusion fitted into the first recess to obtain the battery.

[0103] In this embodiment, the chemical formula of the positive electrode active material is LiMn. 0.61 Fe 0.39 PO4 has a particle size distribution of D10 = 0.252, D50 = 0.524, and D90 = 3.185; the thickness d of the positive electrode active layer is 200 μm, R1 = 100 μm, R2 = 50 μm, and R3 = 100 μm; the particle size distribution of the negative electrode active material is D10 = 5.289 μm, D50 = 9.919 μm, and D90 = 17.116 μm. The relationship between the particle size distribution of the positive electrode active material and the thickness of the positive electrode active layer, R1, R2, and R3 is calculated, as shown in Table 1.

[0104] Example 2

[0105] The battery preparation method provided in this embodiment is basically the same as that in Embodiment 1, except that:

[0106] In this embodiment, R1 = 140 μm, R2 = 50 μm, R3 = 140 μm, and the particle size distribution of the negative electrode active material is D10 = 5.289 μm, D50 = 9.919 μm, and D90 = 17.116 μm. The relationship between the particle size distribution of the positive electrode active material and the thickness of the positive electrode active layer, R1, R2, and R3 is calculated, as shown in Table 1.

[0107] Example 3

[0108] The battery preparation method provided in this embodiment is basically the same as that in Embodiment 1, except that:

[0109] In this embodiment, R1 = 60 μm, R2 = 50 μm, and R3 = 60 μm; the particle size distribution of the negative electrode active material is D10 = 5.289 μm, D50 = 9.919 μm, and D90 = 17.116 μm. The relationship between the particle size distribution of the positive electrode active material and the thickness of the positive electrode active layer, R1, R2, and R3 is calculated, as shown in Table 1.

[0110] Example 4

[0111] The battery preparation method provided in this embodiment is basically the same as that in Embodiment 1, except that:

[0112] In this embodiment, R1 = 100 μm, R2 = 30 μm, and R3 = 100 μm; the particle size distribution of the negative electrode active material is D10 = 5.289 μm, D50 = 9.919 μm, and D90 = 17.116 μm. The relationship between the particle size distribution of the positive electrode active material and the thickness of the positive electrode active layer, R1, R2, and R3 is calculated, as shown in Table 1.

[0113] Example 5

[0114] The battery preparation method provided in this embodiment is basically the same as that in Embodiment 1, except that:

[0115] In this embodiment, R1 = 100 μm, R2 = 50 μm, and R3 = 110 μm; the particle size distribution of the negative electrode active material is D10 = 5.289 μm, D50 = 9.919 μm, and D90 = 17.116 μm. The relationship between the particle size distribution of the positive electrode active material and the thickness of the positive electrode active layer, R1, R2, and R3 is calculated, as shown in Table 1.

[0116] Example 6

[0117] The battery preparation method provided in this embodiment is basically the same as that in Embodiment 1, except that:

[0118] In this embodiment, R1 = 100 μm, R2 = 50 μm, and R3 = 90 μm; the particle size distribution of the negative electrode active material is D10 = 5.289 μm, D50 = 9.919 μm, and D90 = 17.116 μm. The relationship between the particle size distribution of the positive electrode active material and the thickness of the positive electrode active layer, R1, R2, and R3 is calculated, as shown in Table 1.

[0119] Example 7

[0120] The battery preparation method provided in this embodiment is basically the same as that in Embodiment 1, except that:

[0121] In this embodiment, the thickness d of the positive electrode active layer is 300 μm, R1 = 150 μm, R2 = 75 μm, and R3 = 150 μm; the particle size distribution of the negative electrode active material is D10 = 5.289 μm, D50 = 9.919 μm, and D90 = 17.116 μm. The relationship between the particle size distribution of the positive electrode active material and the thickness of the positive electrode active layer, R1, R2, and R3 is calculated, as shown in Table 1.

[0122] Example 8

[0123] The battery preparation method provided in this embodiment is basically the same as that in Example 5, except that: R3 = 150 μm, and the relationship between the particle size distribution of the positive electrode active material and the thickness of the positive electrode active layer, R1, R2 and R3 is calculated, as shown in Table 1.

[0124] Comparative Example 1

[0125] The battery preparation method provided in this comparative example includes the following steps:

[0126] 1. A slurry including a positive electrode active material is injected into a positive electrode rectangular mold. Then, a positive electrode current collector is laid on the surface of the positive electrode mold, and the positive electrode sheet is baked and compacted to obtain a positive electrode sheet. The obtained positive electrode sheet includes a positive electrode current collector and a positive electrode active layer covering at least one side of the positive electrode current collector.

[0127] 2. A slurry containing a negative electrode active material is injected into a negative electrode rectangular mold. Then, a negative electrode current collector is laid on the surface of the negative electrode mold, and the negative electrode sheet is baked and compacted to obtain a negative electrode sheet. The obtained negative electrode sheet includes a negative electrode current collector and a negative electrode active layer covering at least one side of the negative electrode current collector.

[0128] 3. The positive electrode, separator, and negative electrode are stacked to obtain the battery.

[0129] In this embodiment, the chemical formula of the positive electrode active material is LiMn. 0.61 Fe 0.39 PO4 has a particle size distribution of D10 = 0.252, D50 = 0.524, and D90 = 3.185. The thickness d of the positive electrode active layer is 200 μm. The relationship between the particle size distribution of the positive electrode active material and the thickness of the positive electrode active layer is calculated, as shown in Table 1.

[0130] Comparative Example 2

[0131] The preparation method of the battery provided in this comparative example is basically the same as that in Example 1, except that R1 = 180 μm, R3 = 180 μm, and the relationship between the particle size distribution of the positive electrode active material and the thickness of the positive electrode active layer, R1, R2 and R3 is calculated, as shown in Table 1.

[0132] Comparative Example 3

[0133] The preparation method of the battery provided in this comparative example is basically the same as that in Example 1, except that: R1 = 40 μm, R3 = 40 μm, and the relationship between the particle size distribution of the positive electrode active material and the thickness of the positive electrode active layer, R1, R2 and R3 is calculated, as shown in Table 1.

[0134] Comparative Example 4

[0135] The preparation method of the battery provided in this comparative example is basically the same as that in Example 4, except that: R1 = 10 μm, R3 = 10 μm, and the relationship between the particle size distribution of the positive electrode active material and the thickness of the positive electrode active layer, R1, R2 and R3 is calculated, as shown in Table 1.

[0136] Comparative Example 5

[0137] The preparation method of the battery provided in this comparative example is basically the same as that in Example 6, except that: R3 = 50 μm, and the relationship between the particle size distribution of the positive electrode active material and the thickness of the positive electrode active layer, R1, R2 and R3 is calculated, as shown in Table 1.

[0138] Comparative Example 6

[0139] The battery preparation method provided in this embodiment is basically the same as that in Example 5, except that: R1 = 100 μm, R2 = 4 μm, R3 = 100 μm, and the relationship between the particle size distribution of the positive electrode active material and the thickness of the positive electrode active layer, R1, R2 and R3 is calculated, as shown in Table 1.

[0140] Table 1

[0141]

[0142]

[0143] Test example:

[0144] Impedance tests were performed on all the batteries provided in the examples and comparative examples, including the following steps: using the EIS (Electrochemical Impedance Spectroscopy) method, the positive and negative electrodes of the prepared stacked batteries were connected to the electrochemical workstation, and EIS tests were performed using electrochemical analysis software. The test data were then disassembled and analyzed. The specific test data are shown in Table 2.

[0145] Table 2:

[0146] Serial Number Rw / Ω Example 1 <![CDATA[35.32×10 - 3]]> Example 2 <![CDATA[48.49×10 - 3]]> Example 3 <![CDATA[49.47×10 - 3]]> Example 4 <![CDATA[38.06×10 - 3]]> Example 5 <![CDATA[41.76×10 - 3]]> Example 6 <![CDATA[42.47×10 - 3]]> Example 7 <![CDATA[59.58×10 - 3]]> Example 8 <![CDATA[45.54×10 - 3]]> Comparative Example 1 <![CDATA[74.87×10 - 3]]> Comparative Example 2 <![CDATA[69.98×10 - 3]]> Comparative Example 3 <![CDATA[72.07×10 - 3]]> Comparative Example 4 <![CDATA[73.29×10 - 3]]> Comparative Example 5 <![CDATA[68.12×10 - 3]]> Comparative Example 6 <![CDATA[74.23×10 - 3]]>

[0147] According to the data in Table 2, comparing the electrode sheets provided in Examples 1-8 and Comparative Examples 1-6, it can be seen that when the electrode sheet is designed with a slot and satisfies 0.2d < R1(0.8D50+0.1D10+0.1D90) < 0.6d; 0.2d < R3(0.8D50+0.1D10+0.1D90) < 0.6d, the impedance Rw of the battery can be significantly reduced.

[0148] Comparing Examples 1-6, it can be seen that, since Examples 1, 4-6 further satisfy 0.35d < R1(0.8D50+0.1D10+0.1D90) < 0.45d; and / or 0.35d < R3(0.8D50+0.4D10+0.4D90) < 0.45d, the electrode provided therein can further reduce the impedance Rw of the battery.

[0149] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A positive electrode plate, characterized in that, The positive electrode includes a positive current collector and a positive active layer covering at least one side of the positive current collector. The positive active layer includes spaced-apart first protrusions, with a first recess between two adjacent first protrusions. The first protrusions are fitted into the second recesses, wherein the interval between adjacent first protrusions is R1. The thickness of the positive electrode active layer is d, and the positive electrode active layer includes a positive electrode active material. The D50, D10, D90 of the positive electrode active material and R1, d satisfy: 0.2d < R1(0.8D50+0.1D10+0.1D90) < 0.6d.

2. The positive electrode sheet according to claim 1, characterized in that, 0.35d<R1(0.8D50+0.1D10+0.1D90)<0.45d.

3. The positive electrode sheet according to claim 1 or 2, characterized in that, The particle size distribution of the positive electrode active material satisfies: 0.15μm < D10 < 0.3μm; And / or, 0.4μm < D50 < 0.6μm; And / or, 2μm < D90 < 5μm.

4. The positive electrode sheet according to any one of claims 1-3, characterized in that, d≤200μm.

5. A battery, characterized in that, Includes the positive electrode sheet as described in any one of claims 1-4.

6. The battery according to claim 5, characterized in that, The battery further includes a negative electrode sheet, which includes a negative electrode current collector and a negative electrode active layer covering at least one side of the negative electrode current collector; the negative electrode active layer includes second protrusions spaced apart, and a second pit is formed between two adjacent second protrusions, with the second protrusions fitting into the first pit; the width of the second pit is R3; the D50, D10, D90 of the positive electrode active material and R3, d satisfy: 0.2d < R3(0.8D50+0.1D10+0.1D90) < 0.6d; The depth of the second pit is R2, which satisfies: d - (4d) 2 -R1 2 ) 0.5 / 2≤R2<0.6d.

7. The battery according to claim 6, characterized in that, 0.35d<R3(0.8D50+0.4D10+0.4D90)<0.45d.

8. The battery according to any one of claims 6-7, characterized in that, 0.8≤R1 / R3≤1.

2.

9. The battery according to claim 8, characterized in that, 0.9≤R1 / R3≤1.

1.

10. The battery according to any one of claims 6-9, characterized in that, The negative electrode active layer comprises a negative electrode active material, and the particle size distribution of the negative electrode active material satisfies: 4.0 μm ≤ D10 ≤ 9.0 μm; And / or, 9.0μm≤D50≤16.0μm; And / or, 15.0μm≤D90≤26.0μm.

11. A method for preparing a battery according to any one of claims 6-10, characterized in that, Includes the following steps: A slurry containing a positive electrode active material is injected into a positive electrode mold having a first protrusion and a first pit. Then, a positive electrode current collector is laid on the surface of the positive electrode mold, and the positive electrode sheet is obtained by baking and compaction. A slurry containing a negative electrode active material is injected into a negative electrode mold having a second protrusion and a second pit. Then, a negative electrode current collector is laid on the surface of the negative electrode mold, and the negative electrode sheet is obtained by baking and compaction. The positive electrode, the separator, and the negative electrode are stacked together, with the first protrusion fitted into the second recess and the second protrusion fitted into the first recess, to obtain a battery.

12. A battery pack, characterized in that, Includes the battery as described in any one of claims 5-10.

13. An electrical appliance, characterized in that, Includes the battery as described in any one of claims 5-10 or the battery pack as described in claim 12.

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