Positive electrode plate and its manufacturing method, battery cell, battery and power consumption device

Abstract

The present application provides a positive electrode plate and a manufacturing method thereof, a battery cell, a battery, and a power consumption device, which belong to the battery technical field. The positive electrode plate includes a positive electrode current collector and a first film layer and a second film layer disposed on the same side of at least one surface of the positive electrode current collector, wherein the first film layer includes a first active material, the first active material including at least one of an olivine structure material and a spinel structure material, and the second film layer includes a second active material, the second active material including a layered structure material, and the resistivity R1 of the first active material and the resistivity R2 of the second active material satisfy the relationship 20≦R2 / R1≦500. The technical solutions of the embodiments of the present application can improve the performance of battery cells.

Description

[Technical Field]

[0001] This application relates to the battery technology field, and more particularly to positive electrode plates and methods for manufacturing the same, battery cells, batteries and power consumption devices. [Background technology]

[0002] In recent years, the range of applications for lithium-ion batteries has expanded considerably. They are widely used in energy storage and power systems such as hydroelectric, thermal, wind, and solar power plants, as well as in multiple fields including power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace.

[0003] As a component of a battery cell, the performance of the positive electrode plate is crucial to the overall performance of the battery cell. Therefore, how to provide positive electrode plates that improve battery cell performance is an urgent technical challenge that needs to be addressed. [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] This application has been made in view of the above-mentioned problems, and its purpose is to provide a positive electrode plate that improves the performance of a battery cell. [Means for solving the problem]

[0005] To achieve the above objective, this application provides a positive electrode plate, a method for manufacturing the same, a battery cell, a battery, and a power consumption device.

[0006] According to the first embodiment, a positive electrode plate is provided, comprising a positive electrode current collector and a first film layer and a second film layer on the same side of at least one surface of the positive electrode current collector, wherein the first film layer comprises a first active material, the first active material comprising at least one of an olivine structure material and a spinel structure material, the second film layer comprises a second active material, the second active material comprising a layered structure material, and the resistivity R1 of the first active material and the resistivity R2 of the second active material satisfy 20 ≤ R2 / R1 ≤ 500.

[0007] Embodiments of the present application provide a positive electrode plate, including a first film layer and a second film layer provided on the same side of at least one surface of the positive electrode current collector and the positive electrode current collector. The first film layer contains a first active material, and the first active material contains at least one of a material with an olivine structure and a material with a spinel structure. The second film layer contains a second active material that is a material with a layered structure. A battery cell manufactured with the first active material has relatively high reliability, and a battery cell manufactured with the second active material has a high energy density. By providing the first film layer and the second film layer, on the one hand, it is beneficial for both the energy density and reliability of the battery cell. On the other hand, it can reduce the possibility of the first active material adhering to the surface of the second active material, further reduce the electrons gathering on the surface of the second active material, and reduce the risk of excessive lithium ion desorption in the second active material, which is beneficial for improving the cycle performance of the battery cell. The resistivity R1 of the first active material and the resistivity R2 of the second active material satisfy 20 ≤ R2 / R1 ≤ 500. In this way, the difference in resistivity between the first active material and the second active material is relatively small, which can reduce the influence of the aggregation of electrons on the surface of the second active material on the desorption of lithium ions from the second active material, and thereby is beneficial for improving the cycle performance of the battery cell. Therefore, the technical solution of the embodiments of the present application is beneficial for improving the performance of the battery cell.

[0008] In one possible implementation, the resistivity R1 of the first active material and the resistivity R2 of the second active material satisfy 50 ≤ R2 / R1 ≤ 300.

[0009] In the above technical solution, 50 ≤ R2 / R1 ≤ 300. In this way, it is beneficial for further reducing the electrons gathering on the surface of the second active material, and thereby is beneficial for further improving the cycle performance of the battery cell.

[0010] In one possible implementation, the resistivity R1 of the first active material is 10 Ω·cm to 80 Ω·cm, and optionally, 20 Ω·cm to 60 Ω·cm. In this way, it is easy to manufacture the first active material, and at the same time, it is beneficial to balance the conductivity of the first film layer and the cycle performance of the battery cell.

[0011] In one possible implementation, the resistivity R2 of the second active material is 1500 Ω·cm to 15000 Ω·cm, and optionally, 3000 Ω·cm to 9000 Ω·cm. In this way, it is easy to manufacture the second active material, and at the same time, it is beneficial to balance the conductivity of the second film layer and the cycle performance of the battery cell.

[0012] In one possible implementation, the second film layer is located on the surface of the first film layer away from the positive current collector.

[0013] In the above technical solution, the second film layer is located on the surface of the first film layer away from the positive current collector. In this way, it is beneficial to reduce the transmission path of lithium ions to the second active material, beneficial to exert the performance of the second active material, and thereby beneficial to improve the energy density and cycle performance of the battery cell.

[0014] In one possible implementation, the first film layer is located on the surface of the second film layer away from the positive current collector.

[0015] In the above technical solution, the first film layer is located on the surface of the second film layer away from the positive current collector. The first film layer is located on the outermost side of the positive current collector. In this way, it is beneficial to improve the reliability of the battery cell and reduce the risk of ignition and explosion.

[0016] In one possible implementation, the first active material includes a first active material core and a first coating layer covering the first active material core. The first active material core includes at least one of a material with an olivine structure and a material with a spinel structure. The first coating layer includes a carbon material.

[0017] In the above technical solution, covering the first active material core with the first coating layer is advantageous for improving the electrical conductivity performance of the first active material.

[0018] In one possible implementation, the material with the olivine structure is LiFe c , 2 , 1-c-d , d , 1-a-b , 2 Mn x M 1 y PO4, where 0 ≦ x ≦ 1, 0 ≦ y < 1, 0 ≦ x + y ≦ 1, and M 1 includes at least one of other transition metal elements or non-transition metal elements other than Fe and Mn. Optionally, M 1 includes at least one of Cr, Mg, Ti, Al, Zn, W, Nb, Zr. Optionally, the LiFe 1-x-y Mn x M 1 y PO4 includes at least one of LiFePO4, LiMnPO4, LiFe 0.5 Mn 0.5 PO4. Thus, the stability of the material with the olivine structure is relatively high, which is advantageous for improving the reliability of the battery cell.

[0019] In one possible implementation, the material with the spinel structure is at least one of LiMn2O4, LiNi e Mn​​​​​​​​​​​​​​​​​​​​​It contains at least one of Co, Ni, and Mn, where 0 < a < 1, 0 < b < 1, 0 < a + b < 1, 0 < c < 1, 0 < d < 1, and 0 < c + d < 1. The layered structure material has a relatively high gram capacity, which is advantageous for improving the energy density of the battery cell.

[0021] In one possible implementation, the thickness d1 of the first film layer is 40 μm to 160 μm, and optionally, 60 μm to 140 μm.

[0022] In the above technical solution, by reasonably setting the thickness of the first film layer, it is advantageous for achieving both the energy density and reliability of the battery cell.

[0023] In one possible implementation, the thickness d2 of the second film layer is 40 μm to 160 μm, and optionally, 60 μm to 140 μm.

[0024] In the above technical solution, by reasonably setting the thickness of the second film layer, it is advantageous for achieving both the energy density and reliability of the battery cell.

[0025] In one possible implementation, based on the total weight of the first film layer, the weight percentage content of the first active material is 90 wt% to 99 wt%, and optionally, 96 wt% to 98 wt%, and / or based on the total weight of the second film layer, the weight percentage content of the second active material is 90 wt% to 99 wt%, and optionally, 96 wt% to 98 wt%.

[0026] In the above technical solution, by reasonably setting the mass ratio of the first active material to the first film layer, it is advantageous for improving the comprehensive performance of the first film layer, for balancing the energy density, reliability, conductivity, and adhesion of the first film layer of the battery cell, and by reasonably setting the mass ratio of the second active material to the second film layer, it is advantageous for improving the comprehensive performance of the second film layer, and for balancing the energy density, reliability, conductivity, and adhesion of the second film layer of the battery cell.

[0027] In one possible implementation, the weight percentage content of the conductive agent in the first film layer is 0.1 wt% to 1 wt%, selectively 0.3 wt% to 0.6 wt%, based on the total weight of the first film layer, and / or, the weight percentage content of the conductive agent in the second film layer is 0.1 wt% to 1 wt%, selectively 0.3 wt% to 0.6 wt%, based on the total weight of the second film layer.

[0028] In the above proposed technology, by rationally setting the content of the conductive agent in the first film layer, it is advantageous to achieve both the conductivity and adhesive performance of the first film layer and the energy density and reliability of the battery cell. Similarly, by rationally setting the content of the conductive agent in the second film layer, it is advantageous to achieve both the conductivity and adhesive performance of the second film layer and the energy density of the battery cell.

[0029] In one possible implementation, the conductive agent includes at least one of superconducting carbon, conductive carbon black, Ketjenblack, carbon dots, and carbon fibers. This makes it easier to flexibly select the type of conductive agent depending on the actual situation.

[0030] In one possible implementation, the weight percentage content of the adhesive in the first film layer is 1 wt% to 2 wt%, selectively 1.2 wt% to 1.4 wt%, based on the total weight of the first film layer, and / or, the weight percentage content of the adhesive in the second film layer is 1 wt% to 2 wt%, selectively 1.2 wt% to 1.4 wt%, based on the total weight of the second film layer.

[0031] In the above proposed technology, by rationally setting the adhesive content in the first film layer, it is advantageous to improve the adhesion between the first film layer and the second film layer or the positive electrode current collector, thereby reducing the risk of wrinkle formation in the positive electrode plate, and at the same time, it is advantageous to balance the conductivity of the first film layer with the energy density and reliability of the battery cell. By rationally setting the adhesive content in the second film layer, it is advantageous to improve the adhesion between the second film layer and the first film layer or the positive electrode current collector, thereby reducing the risk of wrinkle formation in the positive electrode plate, and at the same time, it is advantageous to balance the conductivity of the second film layer with the energy density of the battery cell.

[0032] In one possible implementation, the adhesive comprises at least one of the following: polyvinylidene fluoride, styrene polybutyl rubber, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene ternary copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene ternary copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trichloroethylene copolymer, and fluorine-containing acrylate resin, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, and polyarylate.

[0033] According to a second aspect, a method for manufacturing a positive electrode plate is provided, characterized by providing a positive electrode current collector and manufacturing a first film layer and a second film layer on the same side of at least one surface of the positive electrode current collector, wherein the first film layer comprises a first active material, the first active material comprising at least one of an olivine structure material and a spinel structure material, the second film layer comprises a second active material, the second active material comprising a layered structure material, and the resistivity R1 of the first active material and the resistivity R2 of the second active material satisfy 20 ≤ R2 / R1 ≤ 500. When a positive electrode plate manufactured by this method is applied to a battery cell, it is advantageous in improving the performance of the battery cell.

[0034] A third aspect provides a battery cell including a positive electrode plate in the first aspect and any one thereof.

[0035] According to the fourth aspect, a battery is provided that includes the battery cell described in the third aspect.

[0036] According to the fifth aspect, a power consumption device including the battery described in the fourth aspect is provided.

[0037] Embodiments of this application provide a positive electrode plate and include a positive electrode current collector and a first and second film layer provided on the same side of at least one surface of the positive electrode current collector. The first film layer includes a first active material, the first active material includes at least one of an olivine structure material and a spinel structure material, and the second film layer includes a second active material, the second active material including a layered structure material. A battery cell made with the first active material has relatively high reliability, and a battery cell made with the second active material has high energy density. The placement of the first and second film layers is advantageous in achieving both energy density and reliability of the battery cell, on the one hand, and on the other hand, it can reduce the possibility of the first active material adhering to the surface of the second active material, further reducing the accumulation of electrons on the surface of the second active material and reducing the risk of excessive desorption of lithium ions in the second active material, which is advantageous in improving the cycle performance of the battery cell. The resistivity R1 of the first active material and the resistivity R2 of the second active material satisfy 20 ≤ R2 / R1 ≤ 500. Thus, the difference in resistivity between the first and second active materials is relatively small, which reduces the influence of electron aggregation on the surface of the second active material on lithium ion desorption from the second active material, thereby improving the cycle performance of the battery cell. Therefore, the technical invention of the embodiment of this application is advantageous in improving the performance of the battery cell. [Brief explanation of the drawing]

[0038] [Figure 1] This is a schematic diagram of a positive electrode plate according to one embodiment of this application. [Figure 2]This is a schematic diagram of a positive electrode plate according to one embodiment of this application. [Figure 3] This is a schematic diagram of a positive electrode plate according to one embodiment of this application. [Figure 4] This is a schematic diagram of a method for manufacturing a positive electrode plate according to one embodiment of this application. [Figure 5] This is a schematic diagram of a battery cell according to one embodiment of the present application. [Figure 6] This is a schematic diagram of a battery module according to one embodiment of the present application. [Figure 7] This is a schematic diagram of a battery according to one embodiment of the present application. [Figure 8] This is a schematic diagram of a power consumption device according to one embodiment of this application. [Modes for carrying out the invention]

[0039] The following describes in detail embodiments specifically disclosing the positive electrode plate and its manufacturing method, battery cell, battery and power consumption device of this application, with appropriate reference to the drawings. However, unnecessary detailed explanations may be omitted. For example, detailed explanations of well-known matters and repeated explanations of structures that are actually the same may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to make it easily understandable to those skilled in the art. The drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and are not intended to limit the topics described in the claims.

[0040] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, which define the boundary of a particular range. The range thus limited may or may not include the limit value, and any combination is possible, that is, any lower limit may be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 are also conceivable. Furthermore, if the minimum range values ​​are listed as 1 and 2, and the maximum range values ​​are listed as 3, 4 and 5, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 are all conceivable. In this application, unless otherwise specified, the numerical range “ab” represents an abbreviated expression for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have already been listed in this specification, and "0-5" is simply a shortened representation of combinations of these numbers. Also, expressing a parameter as an integer ≥ 2 is equivalent to disclosing that this parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0041] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical inventions.

[0042] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical concepts.

[0043] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the fact that the method includes steps (a) and (b) means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, the fact that the method mentioned above may further include step (c) means that step (c) may be added to the method in any order, for example the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), and so on.

[0044] Unless otherwise specified, the terms “includes” and “inclusion” as used in this application may represent an open or closed configuration. For example, the terms “includes” and “inclusion” may mean that other components not listed may be included or inclusion, or that only the listed components may be included or inclusion.

[0045] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following conditions satisfy "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) but B is true (or exists); and both A and B are true (or exist).

[0046] This application uses lithium-ion batteries as an example, which are typical power batteries that charge and discharge through a chemical reaction in which lithium ions are desorbed and absorbed between the positive and negative electrodes. Therefore, lithium-ion batteries are also called rocking chair type batteries. During the charging process of a lithium-ion battery, lithium ions are desorbed from the positive electrode, move by conduction of the electrolyte, and absorbed into the negative electrode active material. During the discharging process, lithium ions are desorbed from the negative electrode, move by conduction of the electrolyte, and absorbed into the positive electrode active material.

[0047] It should be understood that the terms "lithium intercalation" and "intercalation" described in this application refer to the process by which lithium ions are intercalated into the positive electrode active material or negative electrode active material by an electrochemical reaction, while the terms "release," "lithium desorption," and "desorption-intercalation" described in this application refer to the process by which lithium ions are desorbed from the positive electrode active material or negative electrode active material by an electrochemical reaction.

[0048] Lithium-ion batteries are widely used in fields such as mobile phones, electric vehicles, and power storage stations due to their characteristics such as high energy density, high voltage, and long cycle performance. As a component of the battery cell, the performance of the positive electrode plate is extremely important to the performance of the battery cell.

[0049] The positive electrode plate includes a positive electrode current collector and a film layer coated on the surface of the positive electrode current collector. The active material in this film layer is usually lithium iron phosphate having an olivine structure or a ternary material having a layered structure. When the film layer of the positive electrode plate contains only lithium iron phosphate active material, the battery cell manufactured with this positive electrode plate has relatively high reliability, but the energy density of this battery cell is relatively low. When the film layer of the positive electrode plate contains only ternary active material, the battery cell manufactured with this positive electrode plate has relatively high energy density, but the reliability of this battery cell is relatively low.

[0050] Mixing lithium iron phosphate and lithium nickel-cobalt aluminate to produce a film layer on the surface of the positive electrode current collector as the active material is advantageous for achieving both energy density and reliability in battery cells. However, after mixing lithium iron phosphate and lithium nickel-cobalt aluminate, the lithium iron phosphate coats the surface of the lithium nickel-cobalt aluminate, and because the difference in conductivity between lithium iron phosphate and lithium nickel-cobalt aluminate is relatively large, a large number of electrons accumulate on the surface of the lithium nickel-cobalt aluminate during the charging and discharging process of the battery cell, affecting the desorption and intersorption of lithium ions, and thereby affecting the cycle performance of the battery cell.

[0051] In view of this, the present application provides a positive electrode plate comprising a positive electrode current collector and a first and second film layer provided on the same side of at least one surface of the positive electrode current collector. The first active material in the first film layer has an olivine structure and / or spinel structure, and the second active material in the second film layer has a layered structure, and the resistivity R1 of the first active material and the resistivity R2 of the second active material satisfy 20 ≤ R2 / R1 ≤ 500. Thus, the first and second active materials are located in different film layers, which reduces the possibility of the first active material adhering to the surface of the second active material and reduces the difference in resistivity between the first and second active materials, thereby improving the effect of electron aggregation on the surface of the second active material on lithium ion desorption from the second active material, and is advantageous in improving the cycle performance of the battery cell.

[0052] [Positive electrode plate] Figure 1 is a schematic diagram of a positive electrode plate according to one embodiment of the present application. As shown in Figure 1, the positive electrode plate 1 includes a positive electrode current collector 10 and a first film layer 11 and a second film layer 12 provided on the same side of at least one surface of the positive electrode current collector 10.

[0053] The positive electrode current collector 10 has two surfaces provided along its thickness direction, and the first film layer 11 and the second film layer 12 are provided on the same side surface of the positive electrode current collector 10. Selectively, as shown in Figure 1, the first film layer 11 and the second film layer 12 are provided on both surfaces of the positive electrode current collector 10.

[0054] Figure 2 is a schematic diagram of a positive electrode plate according to one embodiment of the present application. In some other embodiments, as shown in Figure 2, a first film layer 11 and a second film layer 12 are provided on one of two opposing surfaces along the thickness direction of the positive electrode current collector 10.

[0055] Selectively, the first film layer 11 may be positioned between the positive electrode current collector 10 and the second film layer 12, along the thickness direction of the positive electrode current collector 10 (for example, the z-direction in Figure 1). In some other embodiments, the second film layer 12 is positioned between the positive electrode current collector 10 and the first film layer 11. The positional relationship between the first film layer 11 and the second film layer 12 may be set according to the actual circumstances, and the embodiments of this application do not specifically limit this.

[0056] The first film layer 11 includes a first active material which comprises at least one of an olivine structure material and a spinel structure material.

[0057] The olivine structure is a type of crystalline structure of a material, and the crystalline structure can indicate the spatial arrangement of atoms in the material. Materials with an olivine structure have relatively high stability, and when applied to battery cells, they can reduce the risk of ignition or explosion under conditions such as high temperatures, which is advantageous in improving the reliability of battery cells.

[0058] The olivine structure material may include various materials such as LiFePO4.

[0059] The spinel structure is a type of crystalline structure of a material. When materials with a spinel structure are used in battery cells, the battery cells have relatively high reliability and are advantageous in reducing the risk of ignition and explosion of the battery cells.

[0060] The spinel structure material may include various materials such as LiMn2O4.

[0061] The second membrane layer 12 contains a second active material which includes a layered material.

[0062] A layered structure is a type of crystalline structure of a material. Materials with a layered structure have a relatively high gram capacity, and when applied to battery cells, they can improve the energy density of the battery cells. Here, gram capacity may refer to the ratio of the amount of electricity that the active material can release to the mass of the active material.

[0063] The layered material may contain multiple materials such as LiMO2, and M contains at least one of Co, Ni, and Mn.

[0064] The first film layer 11 contains the first active material, and the second film layer 12 contains the second active material, and the first film layer 11 and the second film layer 12 are different film layers. In this way, the possibility of the first active material and the second active material coming into contact is reduced, the risk of the first active material adhering to or coating the surface of the second active material is reduced, and the phenomenon of electron aggregation on the surface of the second active material due to the difference in conductivity between the first and second active materials can be improved. This is advantageous in reducing the influence of aggregated electrons on the desorption of lithium ions from the second active material, and is advantageous in improving the cycle performance of the battery cell.

[0065] The first film layer 11 contains a first active material, and the second film layer 12 contains a second active material. Compared to a battery cell containing only the second active material (e.g., a ternary material with a layered structure), a battery cell manufactured with the positive electrode plates of the embodiments of this application has higher reliability and a reduced probability of explosion under extreme conditions (e.g., nail-piercing test conditions).

[0066] The resistivity R1 of the first active material and the resistivity R2 of the second active material satisfy 20 ≤ R2 / R1 ≤ 500.

[0067] The resistivity of the first active material may refer to the resistivity of the first active material in powder form, and the resistivity of the second active material may refer to the resistivity of the second active material in powder form.

[0068] By setting 20 ≤ R2 / R1 ≤ 500, the difference in conductivity between the first and second active materials can be reduced. This is advantageous in improving the aggregation phenomenon of electrons on the surface of the second active material caused by an excessively large difference in conductivity between the first and second active materials. Furthermore, the influence of electron aggregation on the surface of the second active material on the desorption of lithium ions from the second active material can be reduced, thereby lowering the risk of excessive desorption of lithium ions from the second active material, and thus advantageous in improving the cycle performance of the battery cell.

[0069] The cycle performance of a battery cell can be measured by its capacity retention rate, which is the ratio of the retained capacity to the initial discharge capacity. The retained capacity may refer to the discharge capacity of the battery cell after it has completed a certain number of charge-discharge cycles. The initial discharge capacity may refer to the discharge capacity of the battery cell when it undergoes its first charge-discharge test.

[0070] Selectively, the positive electrode current collector 10 may be aluminum foil, or it may be a composite current collector formed of metal and polymer material.

[0071] The positive electrode plate of the embodiment of this application can be used in the manufacture of a battery cell, and the battery cell can be used in various power-consuming devices such as electric vehicles and lighting fixtures.

[0072] Embodiments of this application provide a positive electrode plate 1, comprising a positive electrode current collector 10 and a first film layer 11 and a second film layer 12 provided on the same side of at least one surface of the positive electrode current collector 10. The first film layer 11 comprises a first active material, the first active material comprising at least one of an olivine structure material and a spinel structure material, and the second film layer 12 comprises a second active material comprising a layered structure material. The arrangement of the first film layer 11 and the second film layer 12 is advantageous on the one hand in achieving both energy density and reliability of the battery cell, and on the other hand in reducing the possibility of the first active material adhering to or coating the surface of the second active material, further reducing the accumulation of electrons on the surface of the second active material, and reducing the influence of aggregated electrons on the desorption of lithium ions from the second active material, thereby improving the cycle performance of the battery cell. The resistivity R1 of the first active material and the resistivity R2 of the second active material satisfy 20 ≤ R2 / R1 ≤ 500. Thus, the difference in resistivity between the first and second active materials is relatively small, which can reduce the accumulation of electrons on the surface of the second active material. Furthermore, reducing the accumulation of electrons on the surface of the second active material can mitigate the effect of excessive desorption of lithium ions from the second active material, thereby improving the cycle performance of the battery cell. Therefore, the technical invention of the embodiment of this application is advantageous in improving the performance of the battery cell.

[0073] In some embodiments, the resistivity R1 of the first active material and the resistivity R2 of the second active material satisfy 50 ≤ R2 / R1 ≤ 300.

[0074] In this embodiment, by setting 50 ≤ R2 / R1 ≤ 300, the difference in conductivity between the first and second active materials is further reduced, the accumulation of electrons on the surface of the second active material is further reduced, and the risk of excessive desorption of lithium ions from the second active material is reduced, which is advantageous in improving the cycle performance of the battery cell.

[0075] In some embodiments, the resistivity R1 of the first active material is 10 Ω·cm to 80 Ω·cm.

[0076] Selectively, the resistivity of the first active material is the resistivity measured at 4 MPa. At different pressures, the resistivity of the first active material will differ.

[0077] If the resistivity R1 of the first active material is less than 10 Ω·cm, the complexity of manufacturing the first active material is relatively high. For example, it is necessary to coat the outer layer of the olivine structure material with a large amount of conductive material, resulting in relatively high costs and relatively small improvements in energy density. Furthermore, it is disadvantageous to reduce the difference in resistivity between the first and second active materials, resulting in relatively little improvement in the battery cell's cycle performance.

[0078] If the resistivity R1 of the first active material is greater than 80 Ω·cm, the conductivity of the first active material is relatively low, which is unfavorable for improving the conductivity of the first film layer 11, affecting the overall capacity of the battery cell and resulting in a relatively small improvement in energy density.

[0079] In this embodiment, the resistivity R1 of the first active material is 10 Ω·cm to 80 Ω·cm. This facilitates the manufacturing of the first active material and is advantageous in achieving a balance between the conductivity of the first film layer 11 and the cycle performance of the battery cell, thereby improving the performance of the battery cell.

[0080] Selectively, the resistivity R1 of the first active material is between 20 Ω·cm and 60 Ω·cm. This is advantageous for further improving the performance of the battery cell.

[0081] In some embodiments, the resistivity R2 of the second active material is between 1500 Ω·cm and 15000 Ω·cm.

[0082] Selectively, the resistivity of the second active material is the resistivity measured at 4 MPa. At different pressures, the resistivity of the second active material will differ.

[0083] If the resistivity R2 of the second active material is less than 1500 Ω·cm, the complexity of manufacturing the second active material is relatively high, requiring the synthesis of extremely small crystal grains by adjusting the synthesis process, resulting in relatively high manufacturing costs.

[0084] If the resistivity R2 of the second active material is greater than 15,000 Ω·cm, the conductivity of the second active material is relatively low, which is unfavorable for improving the conductivity of the second film layer 12. Furthermore, it is unfavorable for reducing the difference in resistivity between the first and second active materials, resulting in relatively little improvement in the battery cell's cycle performance.

[0085] By selectively changing the manufacturing process of the second active material, the proportion of neutralizing elements in the second active material, or by providing a conductive coating layer on the second active material, second active materials with different resistivity can be obtained.

[0086] In this embodiment, the resistivity R2 of the second active material is 1500 Ω·cm to 15000 Ω·cm. This facilitates the manufacturing of the second active material and is advantageous in achieving a balance between the conductivity of the second film layer 12 and the cycle performance of the battery cell, thereby improving the performance of the battery cell.

[0087] Selectively, the resistivity R2 of the second active material is between 3000 Ω·cm and 9000 Ω·cm. This is advantageous for further improving the performance of the battery cell.

[0088] In some embodiments, as shown in Figures 1 and 2, the second film layer 12 is located on the surface of the first film layer 11 away from the positive electrode current collector 10.

[0089] The second film layer 12 is located on the surface of the first film layer 11 away from the positive electrode current collector 10; that is, along the thickness direction of the positive electrode current collector 10, the first film layer 11 is located between the positive electrode current collector 10 and the second film layer 12.

[0090] Selectively, the first film layer 11 comes into direct contact with the positive electrode current collector 10. For example, a slurry for manufacturing the first film layer 11 is applied to the surface of the positive electrode current collector 10, and after processes such as drying, the first film layer 11 is formed.

[0091] Selectively, the first film layer 11 comes into direct contact with the second film layer 12. For example, after manufacturing the first film layer, a slurry for manufacturing the second film layer 12 is applied to the surface of the first film layer 11, and after processes such as drying, the second film layer 12 is formed. Alternatively, for example, a slurry corresponding to the surface of the positive electrode current collector 10 is applied simultaneously using a specific application tool to manufacture the first film layer 11 and the second film layer 12.

[0092] In this embodiment, the second active material in the second film layer 12 comprises a material having a layered structure, and the second film layer 12 is located on the surface of the first film layer 11 away from the positive electrode current collector 10, which is advantageous in reducing the transmission path of lithium ions to the second active material, which is advantageous in allowing the performance of the second active material to be exhibited, and thereby is advantageous in improving the energy density and cycle performance of the battery cell.

[0093] Figure 3 is a schematic diagram of a positive electrode plate according to one embodiment of the present application. In some embodiments, as shown in Figure 3, the first film layer 11 is located on the surface of the second film layer 12 away from the positive electrode current collector 10.

[0094] The first film layer 11 is located on the surface of the second film layer 12 away from the positive electrode current collector 10, that is, along the thickness direction of the positive electrode current collector 10, the second film layer 12 is located between the first film layer 11 and the positive electrode current collector 10.

[0095] In this embodiment, the first film layer 11 is located on the surface of the second film layer 12 away from the positive electrode current collector 10, and the first film layer 11 is located on the outermost part of the positive electrode current collector 10. This arrangement is advantageous in improving the reliability of the battery cell and reducing the risk of ignition or explosion.

[0096] In some embodiments, the first active material comprises a first active material core and a first coating layer covering the first active material core, wherein the first active material core comprises at least one of an olivine structure material and a spinel structure material, and the first coating layer comprises a carbon material.

[0097] For example, materials having an olivine structure have relatively poor conductivity, and providing a first coating layer on the surface of the first active material core is advantageous in improving the conductivity of the first active material. For example, by setting the mass ratio of the first coating layer to the first active material, different resistivities of the first active material can be achieved.

[0098] In this embodiment, the first coating layer is advantageous in coating the first active material core and improving the conductive performance of the first active material.

[0099] In some examples, the olivine structure material is LiFe 1-x-y Mn x M 1 y It includes PO4, 0≦x≦1, 0≦y<1, 0≦x+y≦1, and M 1 It contains at least one of the following: Fe, Mn, or other transition metal elements or non-transition metal elements.

[0100] Selectively, M 1 It contains at least one of the following elements: Cr, Mg, Ti, Al, Zn, W, Nb, and Zr.

[0101] Selectively, LiFe 1-x-y Mn x M 1 y PO4 includes LiFePO4, LiMnPO4, and LiFe 0.5 Mn 0.5 It contains at least one of the PO4 compounds. Thus, the stability of olivine-structured materials is relatively high, which is advantageous in improving the reliability of battery cells.

[0102] In some examples, the spinel structure material is LiMn2O4, LiNi eMn 2-e contains at least one of O4, where 0 < e < 2. A battery cell manufactured from a spinel-structured material has relatively high reliability and is advantageous for reducing the probability of ignition and explosion of the battery cell.

[0103] In some embodiments, the layered-structured material includes at least one of LiCoO2, LiMnO2, LiNiO2, LiNiaCobMn1-a-bO2, LiNicCodAl1-c-dO2, nLi2MnO3·(1-n)LiM 2 O2, where 0 < n < 1, and M 2 includes at least one of Co, Ni, Mn, 0 < a < 1, 0 < b < 1, 0 < a + b < 1, 0 < c < 1, 0 < d < 1, 0 < c + d < 1. The layered-structured material has a relatively high gram capacity, which is advantageous for improving the energy density of the battery cell.

[0104] In the embodiments of the present application, during the charge and discharge process of the battery cell, due to reasons such as the desorption, occlusion, and consumption of lithium ions, the content of lithium ions also changes accordingly. Similarly, the content of oxygen ions also changes depending on various situations. Therefore, the general formulas of the olivine-structured material, spinel-structured material, and layered-structured material measured from the positive electrode plate of the battery cell may be different from the general formulas given above. For example, in the case of LiCoO2, the measurable general formula is Li 1+u CoO 2+r where u is a number less than 0 and r is a number less than 0.

[0105] In some embodiments, the thickness d1 of the first film layer 11 is 40 μm to 160 μm.

[0106] When the thickness d1 of the first film layer 11 is 40 μm or more, the stability of the first active material is relatively high, so a thicker first film layer 11 is advantageous in improving the reliability of the battery cell. When the thickness d1 of the first film layer 11 is 160 μm or less, the first film layer 11 occupies an appropriate space, and when the volume of the battery cell is limited, it provides more space for the second film layer 12, which is advantageous in improving the energy density of the battery cell.

[0107] In this embodiment, the thickness d1 of the first film layer 11 is 40 μm to 160 μm, which is advantageous for achieving both reliability and energy density in the battery cell.

[0108] The thicknesses of the first film layer 11 and the second film layer 12 can be measured using a scanning electron microscope. For example, they can be determined from the magnification of the scanning electron microscope and the size of the image obtained by the scanning electron microscope.

[0109] Selectively, the thickness d1 of the first film layer 11 is 60 μm to 140 μm. This is advantageous in further balancing the process feasibility, performance reliability, and energy density of the battery cell.

[0110] In this embodiment, rationally setting the thickness of the first film layer 11 is advantageous in achieving both energy density and reliability of the battery cell.

[0111] In some examples, the thickness d2 of the second film layer 12 is 40 μm to 160 μm.

[0112] When the thickness d2 of the second film layer 12 is 40 μm or more, the gram capacity of the second active material is relatively high, so a thicker second film layer 12 is advantageous in improving the energy density of the battery cell. When the thickness d2 of the second film layer 12 does not exceed 160 μm, if the volume of the battery cell is constant, it is advantageous in improving the reliability of the battery cell because it can provide more space for the first film layer.

[0113] In this embodiment, the thickness d2 of the second film layer 12 is 40 μm to 160 μm, which is advantageous for achieving both reliability and energy density in the battery cell.

[0114] Selectively, the thickness d2 of the second film layer 12 is 60 μm to 140 μm. This is advantageous for further balancing the reliability and energy density of the battery cell.

[0115] In some embodiments, the weight percentage content of the first active material is 90 wt% to 99 wt%, selectively 96 wt% to 98 wt%, for example 97 wt%, based on the total weight of the first membrane layer 11, and / or, the weight percentage content of the second active material is 90 wt% to 99 wt%, selectively 96 wt% to 98 wt%, for example 97 wt%, based on the total weight of the second membrane layer 12.

[0116] When the mass ratio of the first active material to the first film layer 11 is 90 wt% or more, it is advantageous to improve the energy density of the battery cell. When the mass ratio of the first active material to the first film layer 11 exceeds 99 wt%, a conductive agent, adhesive, etc. may be added to the first film layer, which is advantageous to improve the conductivity of the first film layer 11 and the adhesion between the first film layer 11 and the positive electrode current collector 10 or the second film layer 12.

[0117] In this embodiment, by rationally setting the mass ratio of the first active material to the first film layer 11, it is advantageous to improve the overall performance of the first film layer 11 and to balance the energy density and reliability of the battery cell with the conductivity and adhesive strength of the first film layer 11.

[0118] Similarly, rationally setting the mass ratio of the second active material to the second film layer 12 is advantageous in improving the overall performance of the second film layer 12 and in balancing the energy density and reliability of the battery cell with the conductivity and adhesion of the second film layer 12.

[0119] In some embodiments, the weight percentage content of the conductive agent in the first film layer 11 is 0.1 wt% to 1 wt%, selectively 0.3 wt% to 0.6 wt%, for example 0.5 wt%, based on the total weight of the first film layer 11, and / or, the weight percentage content of the conductive agent in the second film layer 12 is 0.1 wt% to 1 wt%, selectively 0.3 wt% to 0.6 wt%, for example 0.5 wt%, based on the total weight of the second film layer 12.

[0120] When the mass ratio of the conductive agent in the first film layer 11 to the first film layer 11 is 0.1 wt% or more, it is advantageous to improve the conductivity of the first film layer 11. When the mass ratio of the conductive agent in the first film layer 11 to the first film layer 11 is 1 wt% or less, more of the first active material or adhesive can be added to the first film layer 11, which is advantageous to improve the adhesion performance of the first film layer 11 or the energy density and reliability of the battery cell.

[0121] When the mass ratio of the conductive agent in the second film layer 12 to the second film layer 12 is 0.1 wt% or more, it is advantageous to improve the conductivity of the second film layer 12. When the mass ratio of the conductive agent in the second film layer 12 to the second film layer 12 is 1 wt% or less, more second active material or adhesive can be added to the second film layer 12, which is advantageous to improve the adhesion performance of the second film layer 12 or the energy density of the battery cell.

[0122] In this embodiment, by rationally setting the content of the conductive agent in the first film layer 11, it is advantageous to achieve both the conductivity and adhesive performance of the first film layer 11 and the energy density and reliability of the battery cell. Similarly, by rationally setting the content of the conductive agent in the second film layer 12, it is advantageous to achieve both the conductivity and adhesive performance of the second film layer 12 and the energy density of the battery cell.

[0123] In some embodiments, the conductive agent includes at least one of superconducting carbon, conductive carbon black, Ketjenblack, carbon dots, and carbon fibers. This makes it easier to flexibly select the type of conductive agent depending on the actual situation.

[0124] In some embodiments, the weight percentage content of the adhesive in the first film layer 11 is 1 wt% to 2 wt%, selectively 1.2 wt% to 1.4 wt%, for example 1.3 wt%, and / or, the weight percentage content of the adhesive in the second film layer 12 is 1 wt% to 2 wt%, selectively 1.2 wt% to 1.4 wt%, for example 1.3 wt%, based on the total weight of the second film layer 12.

[0125] When the mass ratio of the adhesive in the first film layer 11 to the first film layer 11 is 1 wt% or more, it is advantageous to improve the adhesive performance of the first film layer 11. When the mass ratio of the adhesive in the first film layer 11 to the first film layer 11 is 2 wt% or less, more of the first active material or conductive agent can be added to the first film layer 11, which is advantageous to improve the conductivity of the first film layer 11 or the energy density and reliability of the battery cell.

[0126] When the mass ratio of the adhesive in the second film layer 12 to the second film layer 12 is 1 wt% or more, it is advantageous to improve the adhesive performance of the second film layer 12. When the mass ratio of the adhesive in the second film layer 12 to the second film layer 12 is 2 wt% or less, more second active material or conductive agent can be added to the second film layer 12, which is advantageous to improve the conductivity of the second film layer 12 or the energy density of the battery cell.

[0127] In this embodiment, by rationally setting the adhesive content in the first film layer 11, it is advantageous to improve the adhesion between the first film layer 11 and the second film layer 12 or the positive electrode current collector 10, thereby reducing the risk of wrinkle formation in the positive electrode plate, and at the same time, it is advantageous to balance the conductivity of the first film layer 11 with the energy density and reliability of the battery cell. By rationally setting the adhesive content in the second film layer 12, it is advantageous to improve the adhesion between the second film layer 12 and the first film layer 11 or the positive electrode current collector 10, thereby reducing the risk of wrinkle formation in the positive electrode plate, and at the same time, it is advantageous to balance the conductivity of the second film layer 12 with the energy density of the battery cell.

[0128] In the embodiments of this application, the type and content of the adhesive and conductive agent in the first film layer 11 and the second film layer 12 may be flexibly set according to the actual situation, as long as they satisfy the above reasonable range.

[0129] In some embodiments, the adhesive comprises at least one of the following: polyvinylidene fluoride, styrene polybutyl rubber, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene ternary copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene ternary copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trichloroethylene copolymer, and fluorine-containing acrylate resin, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, and polyarylate.

[0130] [Manufacturing method for positive electrode plates] Figure 4 is a schematic diagram of a method for manufacturing a positive electrode plate according to one embodiment of the present application. The embodiment of the present application provides a method for manufacturing a positive electrode plate, and as shown in Figure 4, method 200 includes the following steps.

[0131] In step 210, the positive electrode current collector 10 is provided.

[0132] In step 220, a first film layer 11 and a second film layer 12 are fabricated on the same side of at least one surface of the positive electrode current collector 10. Here, the first film layer 11 contains a first active material, the first active material containing at least one of an olivine structure material and a spinel structure material, the second film layer 12 contains a second active material, the second active material containing a layered structure material, and the resistivity R1 of the first active material and the resistivity R2 of the second active material satisfy 20 ≤ R2 / R1 ≤ 500.

[0133] When a positive electrode plate manufactured using this method is applied to a battery cell, it is advantageous in improving the performance of the battery cell.

[0134] [Battery cell] This application provides a battery cell including the positive electrode plate described in the above embodiment.

[0135] This application does not particularly limit the shape of the battery cell, which may be cylindrical, rectangular, or any other shape.

[0136] Figure 5 is a schematic diagram of a battery cell according to one embodiment of the present application. As shown in Figure 5, the battery cell 3 This includes a case 31, a cover plate 32, and an electrode assembly 33 provided inside the case 31.

[0137] The electrode assembly 33 can be manufactured by winding or laminating the positive electrode plate, negative electrode plate, and separator of this application.

[0138] Selectively, the battery cell 3 further comprises an electrolyte. The electrolyte may be solid, semi-solid, or liquid, and the embodiments of this application do not specifically limit this.

[0139] In some embodiments, battery cells can be assembled into a battery module, and the number of battery cells included in the battery module may be one or more, and the specific number can be selected by those skilled in the art depending on the application and capacity of the battery module.

[0140] Figure 6 is a schematic diagram of a battery module according to one embodiment of the present invention. Referring to Figure 6, in the battery module 4, the multiple battery cells 3 may be arranged sequentially along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, these multiple battery cells 3 may be fixed by fasteners.

[0141] Selectively, the battery module 4 may further include a housing having a housing space, in which a plurality of battery cells 3 are housed.

[0142] [battery] This application provides a battery including the battery cell described in the above embodiment.

[0143] Figure 7 is a schematic diagram of a battery according to one embodiment of the present application. As shown in Figure 7, the present application provides a battery 5 including a battery cell 3 in any one of the above embodiments.

[0144] The battery cell 3 may directly constitute the battery 5, or it may first constitute a battery module, and then the battery 5 may be constituted using the battery module.

[0145] [Power consumption equipment] This application provides a power consumption device including the battery described in the above embodiment.

[0146] Figure 8 is a schematic diagram of a power consumption device according to one embodiment of the present application. As shown in Figure 8, the present application provides a power consumption device 6 including a battery 5 in the above embodiment.

[0147] Examples of the present application are described below. The examples described below are illustrative and are used solely for the purpose of interpreting this application and should not be understood as limitations thereon. Unless specific techniques or conditions are specified in the examples, they shall be carried out in accordance with the techniques or conditions described in the literature in the art or in accordance with the product description. Unless the manufacturer is specified, the reagents or equipment used are all commonly available commercial products.

[0148] [Examples] Example 1 The structure of the positive electrode plate in Example 1 can be seen in Figure 1. In Example 1, the positive electrode current collector 10 was an aluminum foil with a thickness of 13 μm, the thickness d1 of the first film layer 11 was 120 μm, and the thickness d2 of the second film layer 12 was 80 μm.

[0149] In the first film layer 11, the first active material is LiFePO4 (also known as LFP) having a carbon coating layer, and the resistivity of the first active material was 30 Ω·cm at 4 MPa. The first film layer 11 further contains conductive carbon black as a conductive agent and polyvinylidene fluoride (PVDF) as an adhesive. In the first film layer 11, based on the total weight of the first film layer 11, the weight content of the first active material in the first film layer 11 was 97 wt%, the weight content of the conductive agent in the first film layer 11 was 1 wt%, and the weight content of the adhesive in the first film layer 11 was 2 wt%.

[0150] In the second film layer 12, the second active material is LiNi 0.6 Co 0.2 Mn 0.2 The second active material was O2 (also known as NCM), and its resistivity was 4500 Ω·cm at 4 MPa. The second film layer 12 further contained conductive carbon black as a conductive agent and PVDF as an adhesive. In the second film layer 12, based on the total weight of the second film layer 12, the weight content of the second active material in the second film layer 12 was 97 wt%, the weight content of the conductive agent in the second film layer 12 was 1 wt%, and the weight content of the adhesive in the second film layer 12 was 2 wt%.

[0151] The ratio of the resistivity R2 of the second active material to the resistivity R1 of the first active material was 150.

[0152] Example 2-7 The difference between Example 2-7 and Example 1 lies in the difference in R2 / R1.

[0153] In the example, R2 / R1 are 20, 50, 120, 180, 300, and 500, respectively.

[0154] Examples 8-12 Example 8- 12 The difference between this example and Example 1 lies in the different values ​​of R1 and R2.

[0155] In Example 8, R1 is 10, R2 is 1500, and R2 / R1 is 150.

[0156] In Example 9, R1 is 20, R2 is 3000, and R2 / R1 is 150.

[0157] In Example 10, R1 is 50, R2 is 7500, and R2 / R1 is 150.

[0158] In Example 11, R1 is 60, R2 is 9000, and R2 / R1 is 150.

[0159] In Example 12, R1 is 80, R2 is 12000, and R2 / R1 is 150.

[0160] Examples 13-16 The difference between Examples 13-16 and Example 1 lies in the difference in the thickness d1 of the first film layer 11.

[0161] In Examples 13-16, the thickness d1 of the first film layer 11 is 40 μm, 60 μm, 140 μm, and 160 μm, respectively.

[0162] Examples 17-20 The difference between Examples 17-20 and Example 1 lies in the difference in the thickness d2 of the second film layer 12.

[0163] In Examples 17 and 20, two The thicknesses d2 of the film layers 12 are 40 μm, 60 μm, 140 μm, and 160 μm, respectively.

[0164] Examples 21-23 The difference between Example 21 and Example 1 is that the first active material is Lithium Iron Manganese Phosphate (LiFe). 0.5 Mn 0.5 The key is that it is PO4 (abbreviated as LFMP).

[0165] The difference between Example 22 and Example 1 is that the first active material is LiMn2O4.

[0166] The difference between Example 23 and Example 1 is that the first active materials are LiMn2O4 and LiFePO4, and the mass ratio of the two is 1:1.

[0167] Example 24 The difference between Example 24 and Example 1 is that the second active material is a lithium-rich manganese-based material Li 1.2 Ni 0.54 Co 0.13 Mn0. 13 The key feature is that it is O2 (abbreviated as LRNCM).

[0168] Examples 25-26 The difference between Examples 25-26 and Example 1 lies in the structure of the positive electrode plate 1. This structure can be seen in Figures 2 and 3.

[0169] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that it does not employ a structure in which the first and second film layers are stacked.

[0170] In Comparative Example 1, LiFePO4 and LiNi 0.6 Co 0.2 Mn 0.2 After mixing O2 in a specific mass ratio, a conductive agent carbon black, an adhesive PVDF, and N-methylpyrrolidone (NMP) were added to produce a positive electrode active slurry. This slurry was then applied to aluminum foil, dried, and used to form a positive electrode plate.

[0171] Comparative Example 2 The difference between Comparative Example 2 and Comparative Example 1 is that R2 / R1 is 700.

[0172] In Table 1, R1 represents the resistivity of the first active material powder, R2 represents the resistivity of the second active material powder, d1 represents the thickness of the first film layer 11, d2 represents the thickness of the second film layer 12, Q1 represents the cycle capacity retention rate of the battery cell at 25°C, Q2 represents the cycle capacity retention rate of the battery cell at 45°C, and Q3 represents the energy density of the battery cell.

[0173] [Table 1A] [Table 1B] [Table 1C]

[0174] [Manufacturing of battery cells] (1) Manufacturing of positive electrode plates Preparation of the first film layer slurry: The first active material, conductive agent, adhesive, and NMP were mixed and stirred to produce a slurry. Preparation of the second film layer slurry: The second active material, conductive agent, adhesive, and NMP were mixed and stirred to produce a slurry. The types and mixing ratios of the various materials in the first and second film layer slurries are shown in Tables 1 and 2.

[0175] Using an extrusion coating apparatus, the slurry of the first film layer and the slurry of the second film layer were applied to the surface of the positive electrode current collector aluminum foil, and a positive electrode plate was obtained after drying and cold pressing. Here, the thicknesses of the first and second film layers can be found in Table 1.

[0176] (2) Manufacturing of negative electrode plates The negative electrode active material graphite, conductive agent acetylene black, adhesive styrene-butadiene rubber, and thickener sodium carboxymethylcellulose were mixed in a weight ratio of graphite:acetylene black:styrene-butadiene rubber:sodium carboxymethylcellulose = 95:2:2:1. An appropriate amount of deionized water was added and the mixture was thoroughly stirred to form a uniform negative electrode slurry. The slurry was then applied to the copper foil of the negative electrode current collector, dried, and cold-pressed to obtain a negative electrode plate.

[0177] (3) Manufacturing of electrolyte In a glove box under an argon gas atmosphere with a water content of <10 ppm, one or more solvents were mixed in a weight ratio to obtain a mixed solvent. A certain mass of a well-dried lithium salt LiPF6 was then dissolved in the mixed solvent, and an inorganic lithium salt additive was added thereto. After uniform stirring, an electrolyte was obtained.

[0178] (4) Manufacturing of battery cells A positive electrode plate, a separator (polyethylene porous polymer film), and a negative electrode plate are stacked in order, with the separator positioned between the positive and negative electrode plates to act as an separator. The assembly is then wound up to obtain an electrode assembly, which is placed in a case. The manufactured electrolyte is then poured into the case, and the battery cell is obtained through the following processes: vacuum packaging, standing, chemical formation, and shaping.

[0179] [Determination of the first and second active materials] By taking a certain mass of active material layer, preparing a sample through polishing, tableting, etc., and scanning it with an X-ray diffractometer at 5° / min and 10-80°, and comparing it with the characteristic peaks of the corresponding material, the type of active material can be identified.

[0180] [Determination of the resistivity of the active material powder] A sample of a certain mass was weighed, the depth of the material feed cavity of the test equipment (the equipment can be a powder resistivity tester, a Type ST2722 digital four-probe tester) was adjusted, the sample was placed in the material feed cavity, pressure was applied, the pressure was 0 to 25 MPa, and the test results of the powder resistivity at different pressure points were recorded. The resistivity in the embodiments of this application is described using 4 MPa as an example.

[0181] [Cycle performance test] At 25 / 45℃, the battery cell was first charged to 4.3V with a constant current of 1C, then charged again with a constant voltage of 4.3V until the current was 0.05C, and then discharged to 3V with a constant current of 1C. This constitutes one charge-discharge cycle, and the discharge capacity measured here is the discharge capacity of the first cycle. Multiple cycle charge-discharge tests were performed on the battery using the above method, and the discharge capacity at the 200th cycle was detected. The capacity retention rate of the battery cell after the cycle was then calculated using the following formula: Capacity retention rate of the battery after 200 cycles (wt%) = [Discharge capacity at 200th cycle / Discharge capacity at 1st cycle] × 100 wt%.

[0182] [Nail-piercing test] The battery core was fully charged, placed on a nail-piercing sample stand, and a 3mm steel needle was used to pierce the battery electrode plate perpendicular to it at a speed of 1mm / s, continuing until the piercing position approached the geometric center of the piercing surface and the needle was fully pierced or thermal runaway occurred.

[0183] In the embodiments of this application, both smoke emission and failure to ignite or explode indicate that the nail-piercing test has been passed. In other words, it can be shown that the nail-piercing test has been passed without explosion.

[0184] [Energy density test] In a room temperature environment (25℃±2℃), the battery is discharged to the lower limit voltage using a constant current discharge method (1 / 3C rate), then left to stand for 30 minutes. Next, it is charged to the upper cutoff voltage using a constant current constant voltage charging method (constant current 1 / 3C, constant voltage charging to 1 / 20C), then left to stand for 30 minutes. The discharge energy E (calculated in Wh) is calculated, and this process is repeated three times. The average value of the three discharge energies E is taken and divided by the volume V of the hard-case battery cell to obtain the volumetric energy density (calculated in Wh / L) = Eaverage / V.

[0185] As shown in Examples 1-26 and Comparative Example 1-2, by placing the first active material and the second active material on different film layers, and by ensuring that the resistivity of the first active material and the second active material satisfy a certain relationship, the initial capacity decay of the battery cell can be improved, which is advantageous for improving the cycle performance of the battery cell, and thereby advantageous for improving the performance of the battery cell.

[0186] As shown in Example 2-7, rationally setting the resistivity relationship between the first and second active materials is advantageous in further reducing capacity decay in the early stages of the cycle and improving the cycle performance of the battery cell. As shown in Example 8-12, rationally setting the resistivity of the first and second active materials improves the cycle performance of the battery cell while simultaneously facilitating the manufacturing of the first and second active materials. As shown in Example 13-20, rationally setting the thickness of the first and second film layers makes it easier to flexibly select the required energy density, reliability, etc. of the battery cell according to the actual situation, while improving the cycle performance of the battery cell. As shown in Example 21-24, the technical solution of the embodiments of this application can be applied to multiple types of different active materials. As shown in Example 25-26, the technical solution of the embodiments of this application can be applied to positive electrode plates of multiple types of structures.

[0187] It should be noted that this application is not limited to the embodiments described above. The embodiments described above are merely illustrative, and any embodiments that have substantially the same configuration as the technical idea and produce the same effects within the scope of the technical proposal of this application are included within the scope of the technical proposal. Furthermore, other methods that are constructed by adding various modifications to the embodiments that a person skilled in the art could conceive of, and by combining some of the components of the embodiments, are also included within the scope of this application, without departing from the spirit of this application.

Claims

1. It is a positive electrode plate, The positive electrode current collector (10) and a first film layer (11) and a second film layer (12) provided on the same side of at least one surface of the positive electrode current collector (10), wherein, The first film layer (11) comprises a first active material, the first active material comprising at least one of an olivine structure material and a spinel structure material. The second film layer (12) comprises a second active material, and the second active material comprises a layered material. The positive electrode plate is such that the resistivity R1 of the first active material and the resistivity R2 of the second active material satisfy 20 ≤ R2 / R1 ≤ 500.

2. The positive electrode plate according to claim 1, wherein the resistivity R1 of the first active material and the resistivity R2 of the second active material satisfy 50 ≤ R2 / R1 ≤ 300.

3. The positive electrode plate according to claim 1, wherein the resistivity R1 of the first active material is 10 Ω·cm to 80 Ω·cm.

4. The positive electrode plate according to claim 3, wherein the resistivity R1 of the first active material is 20 Ω·cm to 60 Ω·cm.

5. The positive electrode plate according to claim 1, wherein the resistivity R2 of the second active material is 1500 Ω·cm to 15000 Ω·cm.

6. The positive electrode plate according to claim 5, wherein the resistivity R2 of the second active material is 3000 Ω·cm to 9000 Ω·cm.

7. The positive electrode plate according to claim 1, wherein the second film layer (12) is located on the surface of the first film layer (11) away from the positive electrode current collector (10).

8. The positive electrode plate according to claim 1, wherein the first film layer (11) is located on the surface of the second film layer (12) away from the positive electrode current collector (10).

9. The positive electrode plate according to claim 1, wherein the first active material comprises a first active material core and a first coating layer covering the first active material core, the first active material core comprises at least one of the olivine structure material and the spinel structure material, and the first coating layer comprises a carbon material.

10. The material with the olivine structure is LiFe １－ｘ－ｙ Mn ｘ M １ ｙ PO ４ It includes 0 ≤ x ≤ 1, 0 ≤ y < 1, 0 ≤ x + y ≤ 1, and M １ The positive electrode plate according to claim 1, comprising at least one of other transition metal elements or non-transition metal elements other than Fe and Mn.

11. The positive electrode plate according to claim 10, wherein M1 comprises at least one of Cr, Mg, Ti, Al, Zn, W, Nb, and Zr.

12. The positive electrode plate according to claim 10, wherein the LiFe 1-x-y Mn x M 1 y PO 4 comprises at least one of LiFePO 4, LiMnPO 4, and LiFe 0.5 Mn 0.5 PO 4.

13. The material of the spinel structure is LiMn ２ O ４ , LiNi ｅ Mn ２－ｅ O ４ The positive electrode plate according to claim 1, which contains at least one of them, where 0 < e < 2.

14. The layered material is LiCoO ２ LiMnO ２ LiNiO ２ LiNi ａ Co ｂ Mn １－ａ－ｂ O ２ LiNi ｃ Co ｄ Al １－ｃ－ｄ O ２ nLi ２ MnO ３ (1-n)LiM ２ O ２ It includes at least one of the following, where 0 < a < 1, 0 < b < 1, 0 < a + b < 1, 0 < c < 1, 0 < d < 1, 0 < c + d < 1, 0 < n < 1, M ２ The positive electrode plate according to claim 1, comprising at least one of Co, Ni, and Mn.

15. The positive electrode plate according to claim 1, wherein the thickness d1 of the first film layer (11) is 40 μm to 160 μm.

16. The positive electrode plate according to claim 15, wherein the thickness d1 of the first film layer (11) is 60 μm to 140 μm.

17. The positive electrode plate according to claim 1, wherein the thickness d2 of the second film layer (12) is 40 μm to 160 μm.

18. The positive electrode plate according to claim 17, wherein the thickness d2 of the second film layer (12) is 60 μm to 140 μm.

19. Based on the total weight of the first membrane layer (11), the weight percentage content of the first active material is 90 wt% to 99 wt%, and / or, The positive electrode plate according to claim 1, wherein the weight percentage content of the second active material is 90 wt% to 99 wt% based on the total weight of the second film layer (12).

20. The weight percentage content of the first active material is 96 wt% to 98 wt% based on the total weight of the first film layer (11). and / or, The positive electrode plate according to claim 19, wherein the weight percentage content of the second active material is 96 wt% to 98 wt% based on the total weight of the second film layer (12).

21. Based on the total weight of the first film layer (11), the weight percentage content of the conductive agent in the first film layer (11) is 0.1 wt% to 1 wt%. and / or, The positive electrode plate according to claim 1, wherein, based on the total weight of the second film layer (12), the weight percentage content of the conductive agent in the second film layer (12) is 0.1 wt% to 1 wt%.

22. Based on the total weight of the first film layer (11), the weight percentage content of the conductive agent in the first film layer (11) is 0.3 wt% to 0.6 wt%, and / or, The positive electrode plate according to claim 21, wherein, based on the total weight of the second film layer (12), the weight percentage content of the conductive agent in the second film layer (12) is 0.3 wt% to 0.6 wt%.

23. The positive electrode plate according to claim 21, comprising at least one of superconducting carbon, conductive carbon black, Ketjenblack, carbon dots, and carbon fibers as the conductive agent.

24. Based on the total weight of the first film layer (11), the weight percentage content of the adhesive in the first film layer (11) is 1 wt% to 2 wt%. and / or, The positive electrode plate according to claim 1, wherein the weight percentage content of the adhesive in the second film layer (12) is 1 wt% to 2 wt%, based on the total weight of the second film layer (12).

25. Based on the total weight of the first film layer (11), the weight percentage content of the adhesive in the first film layer (11) is 1.2 wt% to 1.4 wt%, and / or, The positive electrode plate according to claim 24, wherein, based on the total weight of the second film layer (12), the weight percentage content of the adhesive in the second film layer (12) is 1.2 wt% to 1.4 wt%.

26. The positive electrode plate according to claim 24, wherein the adhesive comprises at least one of polyvinylidene fluoride, styrene polybutyl rubber, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene ternary copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene ternary copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trichloroethylene copolymer, and fluorine-containing acrylate resin, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, and polyarylate.

27. A method for manufacturing a positive electrode plate, To provide a positive electrode current collector (10), This includes manufacturing a first film layer (11) and a second film layer (12) on the same side of at least one surface of the positive electrode current collector (10), wherein, The first film layer (11) comprises a first active material, the first active material comprising at least one of an olivine structure material and a spinel structure material. The second film layer (12) comprises a second active material, and the second active material comprises a layered material. A method for manufacturing a positive electrode plate, wherein the resistivity R1 of the first active material and the resistivity R2 of the second active material satisfy 20 ≤ R2 / R1 ≤ 500.

28. A battery cell comprising a positive electrode plate according to any one of claims 1 to 26.

29. A battery comprising the battery cell described in claim 28.

30. A power consumption device including a battery as described in claim 29.

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