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] The present application relates to the field of battery technology, and in particular to a positive electrode plate and its manufacturing method, a battery cell, a battery and a power consuming device. [Background technology]

[0002] In recent years, the application range of lithium-ion batteries has become increasingly wider, and they are widely used in energy storage power systems such as hydroelectric power, thermal power, wind power and solar power plants, as well as in multiple fields such as 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 very important to the performance of the battery cell, so how to provide a positive electrode plate to improve the performance of the battery cell is a technical problem that needs to be solved as soon as possible. Summary of the Invention [Problem to be solved by the invention]

[0004] The present application has been made in view of the above-mentioned problems, and its object 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 object, the present application provides a positive electrode plate and a manufacturing method thereof, a battery cell, a battery and a power consuming device.

[0006] According to a first aspect, there is provided a positive electrode plate 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 a resistivity R1 of the first active material and a resistivity R2 of the second active material satisfy 20≦R2 / R1≦500.

[0007] An embodiment of the present application provides a positive electrode plate, comprising 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. The first film layer comprises 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 comprises a second active material including a layered structure material. Battery cells manufactured with the first active material have relatively high reliability, and battery cells manufactured with the second active material have high energy density. The provision of the first film layer and the second film layer is advantageous for achieving both high energy density and reliability of the battery cell, while also reducing the likelihood of the first active material adhering to the surface of the second active material, further reducing electrons gathering on the surface of the second active material and reducing the risk of excessive lithium ion desorption from the second active material, which is advantageous 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 the relationship 20≦R2 / R1≦500. Thus, the difference in resistivity between the first active material and the second active material is relatively small, which can reduce the influence of electron aggregation on the surface of the second active material on the desorption of lithium ions from the second active material, thereby improving the cycle performance of the battery cell. Therefore, the technical solutions of the embodiments of the present application are advantageous to 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, R2 / R1 is 50≦R2 / R1≦300, which is advantageous for further reducing the electrons gathering on the surface of the second active material, and thereby further improving the cycle performance of the battery cell.

[0010] In one possible embodiment, 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, which facilitates the production of the first active material and is advantageous in achieving both the conductivity of the first film layer and the cycle performance of the battery cell.

[0011] In one possible embodiment, 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, which facilitates the production of the second active material and is advantageous in achieving both 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 a surface of the first film layer that is remote from the positive electrode 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 electrode current collector, which is advantageous to reduce the transmission path of lithium ions to the second active material and to bring out the performance of the second active material, thereby improving the energy density and cycle performance of the battery cell.

[0014] In one possible implementation, the first film layer is located on a surface of the second film layer that is remote from the positive electrode 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 electrode current collector, and the first film layer is located on the outermost side of the positive electrode current collector, which is advantageous in improving the reliability of the battery cell and reducing the risk of fire or explosion.

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

[0018] In one possible implementation, the material with olivine structure is LiFe c , b , , 2 , 1-c-d , d , 1-a-b , a , 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, and 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 olivine structure is relatively high, which is advantageous for improving the reliability of the battery cell.

[0019] In one possible implementation, the material with spinel structure includes at least one of LiMn2O4, LiNi e Mn 2-e O4, where 0 < e < 2. The battery cell manufactured with the material with spinel structure has relatively high reliability and is advantageous for reducing the probability of ignition and explosion of the battery cell.

[0020] In one possible implementation, the material with layered structure includes at least one of LiCoO2, LiMnO2, LiNiO2, LiNi a Co b Mn 1-a-b O2, LiNi c Co d Al 1-c-d O2, nLi2MnO3·(1 - n)LiM 2 O2, where 0 < n < 1, and M 2It 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-structured 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, for balancing the energy density, reliability, conductivity, and adhesion of the second film layer of the battery cell.

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

[0028] In the above technical proposal, 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, and 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 comprises at least one of superconducting carbon, conductive carbon black, Ketjen black, carbon dots, and carbon fibers, which facilitates flexible selection of the conductive agent according to actual conditions.

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

[0031] In the above technical solution, by rationally setting the content of adhesive in the first film layer, it is advantageous to improve the adhesive strength between the first film layer and the second film layer or the positive electrode current collector, thereby reducing the risk of wrinkles 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 content of adhesive in the second film layer, it is advantageous to improve the adhesive strength between the second film layer and the first film layer or the positive electrode current collector, thereby reducing the risk of wrinkles 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 polyvinylidene fluoride, styrene polybutyl rubber, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, 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, polyarylate.

[0033] According to a second aspect, there is provided a method for manufacturing a positive electrode plate. This method includes 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 includes a first active material, the first active material including at least one of an olivine structure material and a spinel structure material, 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. When used in a battery cell, the positive electrode plate manufactured by this method is advantageous in improving the performance of the battery cell.

[0034] According to a third aspect, there is provided a battery cell including a positive electrode plate according to the first aspect and any one of the possible realizations thereof.

[0035] According to a fourth aspect, there is provided a battery including the battery cell according to the third aspect.

[0036] According to a fifth aspect, there is provided a power consuming device including a battery according to the fourth aspect.

[0037] An embodiment of the present application provides a positive electrode plate, comprising 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. The first film layer comprises 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 comprises a second active material including a layered structure material. Battery cells manufactured with the first active material have relatively high reliability, and battery cells manufactured with the second active material have high energy density. The provision of the first film layer and the second film layer is advantageous for achieving both high energy density and reliability of the battery cell, while also reducing the likelihood of the first active material adhering to the surface of the second active material, further reducing electrons gathering on the surface of the second active material and reducing the risk of excessive lithium ion desorption from the second active material, which is advantageous 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 the relationship 20≦R2 / R1≦500. Thus, the difference in resistivity between the first active material and the second active material is relatively small, which can reduce the influence of electron aggregation on the surface of the second active material on the desorption of lithium ions from the second active material, thereby improving the cycle performance of the battery cell. Therefore, the technical solutions of the embodiments of the present application are advantageous to improving the performance of the battery cell. [Brief explanation of the drawings]

[0038] [Figure 1] FIG. 1 is a schematic diagram of a positive electrode plate according to an embodiment of the present application. [Figure 2]FIG. 1 is a schematic diagram of a positive electrode plate according to an embodiment of the present application. [Figure 3] FIG. 1 is a schematic diagram of a positive electrode plate according to an embodiment of the present application. [Figure 4] 1 is a schematic diagram of a method for manufacturing a positive electrode plate according to an embodiment of the present application. [Figure 5] 1 is a schematic diagram of a battery cell according to one embodiment of the present application; [Figure 6] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 7] 1 is a schematic diagram of a battery according to one embodiment of the present application. [Figure 8] 1 is a schematic diagram of a power consuming device according to one embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0039] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the positive electrode plate and its manufacturing method, battery cell, battery, and power consumption device of the present application will be described in detail. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of structures that are actually the same may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0040] The "ranges" disclosed in this application are defined in the form of lower and upper limits. A given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive, and may be arbitrarily combined; i.e., any lower limit may be combined with any upper limit to form a single range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are listed as maximum range values, the following ranges are also contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. Unless otherwise specified, the numerical range "ab" in this application is a shorthand notation 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" represents that the specification has already listed all real numbers between "0-5," and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0041] Unless otherwise stated, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0042] Unless otherwise stated, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0043] Unless otherwise specified, all steps in this application may be performed in order or randomly, preferably in order. For example, a description of a method including steps (a) and (b) means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, a description of a method that may further include step (c) means that step (c) may be added to the method in any order, e.g., the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0044] Unless otherwise specified, the terms "comprise" and "comprises" used in this application may be open ended or closed ended. For example, the terms "comprise" and "comprises" may indicate that other components not listed may be further included or included, or that only the listed components may be included or included.

[0045] Unless otherwise stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, "A or B" is satisfied when A is true (or exists) and B is false (or does not exist), when A is false (or does not exist) but B is true (or exists), or when both A and B are true (or exist).

[0046] This application takes a lithium-ion battery as an example. A lithium-ion battery is a typical power battery that is charged and discharged by a chemical reaction in which lithium ions are absorbed and released between the positive and negative electrodes, and is therefore also called a rocking chair battery. During the charging process of a lithium-ion battery, lithium ions are released from the positive electrode, move by the conduction of the electrolyte, and are absorbed into the negative electrode active material. During the discharging process, lithium ions are released from the negative electrode, move by the conduction of the electrolyte, and are absorbed into the positive electrode active material.

[0047] It should be understood that the processes of "lithium absorption" and "absorption" described in this application refer to a process in which lithium ions are absorbed into a positive electrode active material or a negative electrode active material through an electrochemical reaction, and the processes of "release", "lithium desorption", and "desorption absorption" described in this application refer to a process in which lithium ions are desorbed from a positive electrode active material or a negative electrode active material through an electrochemical reaction.

[0048] Due to their high energy density, high voltage, and long cycle life, lithium-ion batteries are widely used in mobile phones, electric vehicles, power storage stations, etc. As the positive electrode plate is a component of the battery cell, the performance of the positive electrode plate is crucial to the performance of the battery cell.

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

[0050] Fabricating a film layer on the surface of the positive electrode current collector as an active material after mixing lithium iron phosphate and lithium nickel cobalt aluminate is advantageous for achieving both high energy density and high reliability of the battery cell. However, after mixing lithium iron phosphate and lithium nickel cobalt aluminate, the lithium iron phosphate is coated on the surface of the lithium nickel cobalt aluminate. Due to the relatively large difference in conductivity between lithium iron phosphate and lithium nickel cobalt aluminate, a large number of electrons will gather on the surface of the lithium nickel cobalt aluminate during the charge and discharge process of the battery cell, affecting the absorption and desorption 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, which includes a positive electrode current collector and 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. The first active material in the first film layer has an olivine structure and / or a 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. In this way, the first active material and the second active material 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, which is advantageous in improving the influence of electron aggregation on the surface of the second active material on lithium ion desorption from the second active material and in improving the cycle performance of the battery cell.

[0052] [Positive electrode plate] 1 is a schematic diagram of a positive electrode plate according to an embodiment of the present application. As shown in FIG. 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 surface on the same side of the positive electrode current collector 10. Optionally, as shown in FIG. 1 , the first film layer 11 and the second film layer 12 are provided on both of the two surfaces of the positive electrode current collector 10.

[0054] 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 FIG. 2, a first film layer 11 and a second film layer 12 are provided on one of two opposing surfaces of a positive electrode current collector 10 along the thickness direction.

[0055] Optionally, the first film layer 11 may be located between the positive electrode current collector 10 and the second film layer 12 along the thickness direction of the positive electrode current collector 10 (e.g., the z direction in FIG. 1 ). In some other embodiments, the second film layer 12 is located 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 actual circumstances, and the embodiments of the present application are not specifically limited thereto.

[0056] The first film layer 11 includes a first active material including 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, which can indicate the order in which atoms are arranged in space in a material. Materials with the olivine structure have relatively high stability, and when applied to battery cells, they can reduce the risk of fire or explosion under conditions such as high temperatures, which is advantageous for improving the reliability of battery cells.

[0058] Olivine structured materials may include a variety of materials such as LiFePO4.

[0059] The spinel structure is a type of crystalline structure of a material. When a material having the spinel structure is used in a battery cell, the battery cell has a relatively high reliability and is advantageous in reducing the risk of fire or explosion of the battery cell.

[0060] Materials with a spinel structure may include a variety of materials such as LiMn2O4.

[0061] The second film layer 12 includes a second active material that includes a layered structure 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 a battery cell, can improve the energy density of the battery cell. Here, gram capacity may refer to the ratio of the amount of electricity that an active material can release to the mass of the active material.

[0063] The layered structure material may include multiple materials, such as LiMO2, where M includes at least one of Co, Ni, and Mn.

[0064] The first film layer 11 includes a first active material, and the second film layer 12 includes a 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 contact between the first active material and the second active material is reduced, reducing the risk that the first active material will adhere to or coat the surface of the second active material. Furthermore, it is possible to improve the aggregation phenomenon of electrons on the surface of the second active material due to the difference in conductivity between the first active material and the second active material, which is advantageous in reducing the effect of the aggregated electrons on the desorption of lithium ions from the second active material and in improving the cycle performance of the battery cell.

[0065] The first film layer 11 includes a first active material, and the second film layer 12 includes a second active material. Compared with a battery cell including only the second active material (e.g., a layered ternary material), a battery cell manufactured with the positive electrode plate of the embodiment of the present application has higher reliability and a reduced probability of explosion under extreme conditions (e.g., under nail penetration test conditions).

[0066] The resistivity R1 of the first active material and the resistivity R2 of the second active material satisfy the relationship 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] Setting R2 / R1 to 20≦R2 / R1≦500 makes it possible to reduce the difference in electrical conductivity between the first active material and the second active material, which is advantageous for improving the phenomenon of electron aggregation on the surface of the second active material caused by an excessively large difference in electrical conductivity between the first active material and the second active material. Furthermore, it is possible to reduce the effect of electron aggregation on the surface of the second active material on the desorption of lithium ions from the second active material, thereby reducing the risk of excessive desorption of lithium ions from the second active material, which is advantageous for improving the cycle performance of the battery cell.

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

[0070] Alternatively, the positive electrode current collector 10 may be an aluminum foil or a composite current collector made of a metal and a polymer material.

[0071] The positive electrode plates of the embodiments of the present application can be used to manufacture battery cells, which can be used in various power consuming devices, such as electric vehicles, lighting fixtures, etc.

[0072] An embodiment of the present application provides a positive electrode plate 1, which 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. The first film layer 11 includes a first active material, which includes at least one of an olivine structure material and a spinel structure material, and the second film layer 12 includes a second active material including a layered structure material. The provision of the first film layer 11 and the second film layer 12 is advantageous for achieving both high energy density and high reliability of the battery cell, while also reducing the possibility that the first active material will adhere to or coat the surface of the second active material, thereby reducing the number of electrons that gather on the surface of the second active material and reducing the effect of the aggregated electrons on the desorption of lithium ions from the second active material, which is advantageous 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 the relationship 20≦R2 / R1≦500. Thus, the difference in resistivity between the first active material and the second active material is relatively small, which can reduce the electrons gathering on the surface of the second active material, and further reduce the electrons gathering on the surface of the second active material, which can reduce 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 solutions of the embodiments of the present application are advantageous to 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 the relationship 50≦R2 / R1≦300.

[0074] In this example, by setting R2 / R1 to 50≦R2 / R1≦300, the difference in electrical conductivity between the first active material and the second active material is further reduced, the electrons that gather on the surface of the second active material are further reduced, and the risk of excessive desorption of lithium ions from the second active material is reduced, which is advantageous for improving the cycle performance of the battery cell.

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

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

[0077] If the resistivity R1 of the first active material is less than 10 Ω·cm, the manufacturing process of the first active material is relatively complicated, for example, it is necessary to coat a large amount of conductive material on the outer layer of the olivine structure material, which results in relatively high costs and a relatively small improvement in energy density. It is also disadvantageous to reduce the difference in resistivity between the first active material and the second active material, and the improvement in the cycle performance of the battery cell is relatively small.

[0078] If the resistivity R1 of the first active material is greater than 80 Ω·cm, the conductive performance 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 the improvement in energy density is relatively small.

[0079] In this example, the resistivity R1 of the first active material is 10 Ω·cm to 80 Ω·cm, which facilitates the production of the first active material and is advantageous in achieving both 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] Optionally, the resistivity R1 of the first active material is 20 Ω·cm to 60 Ω·cm, which 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] Optionally, the resistivity of the second active material is measured at 4 MPa. At different pressures, the resistivity of the second active material is different.

[0083] If the resistivity R2 of the second active material is smaller than 1500 Ω·cm, the manufacturing complexity of the second active material is relatively high, and it is necessary to synthesize extremely small crystal particles by adjusting the synthesis process, which results in a relatively high manufacturing cost.

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

[0085] Optionally, second active materials with different resistivities can be obtained by 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.

[0086] In this example, the resistivity R2 of the second active material is 1500 Ω·cm to 15000 Ω·cm, which facilitates the production of the second active material and is advantageous in achieving both 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] Optionally, the resistivity R2 of the second active material is 3000 Ω·cm to 9000 Ω·cm, which is advantageous for further improving the performance of the battery cell.

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

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

[0090] Optionally, the first film layer 11 is in direct contact with the positive electrode current collector 10. For example, a slurry for producing the first film layer 11 is applied to the surface of the positive electrode current collector 10, and after a process such as drying, the first film layer 11 is formed.

[0091] Alternatively, the first membrane layer 11 may be in direct contact with the second membrane layer 12. For example, after the first membrane layer is manufactured, a slurry for manufacturing the second membrane layer 12 may be applied to the surface of the first membrane layer 11, and after a process such as drying, the second membrane layer 12 may be formed. Alternatively, for example, the first membrane layer 11 and the second membrane layer 12 may be manufactured by simultaneously applying corresponding slurries to the surface of the positive electrode current collector 10 using a specific coating tool.

[0092] In this embodiment, the second active material in the second film layer 12 includes 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 paths of lithium ions to the second active material and in enabling the second active material to exhibit its performance, thereby improving the energy density and cycle performance of the battery cell.

[0093] 3 is a schematic diagram of a positive electrode plate according to one embodiment of the present application. In some embodiments, as shown in FIG. 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 membrane layer 11 is located on the surface of the second membrane layer 12 that is farther from the positive electrode current collector 10; that is, along the thickness direction of the positive electrode current collector 10, the second membrane layer 12 is located between the first membrane 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 that is farther from the positive electrode current collector 10, and the first film layer 11 is located on the outermost side of the positive electrode current collector 10, which is advantageous in improving the reliability of the battery cell and reducing the risk of fire or explosion.

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

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

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

[0099] In some embodiments, the olivine structure material is LiFe 1-x-y Mn x M 1 y PO4, 0≦x≦1, 0≦y<1, 0≦x+y≦1, and M 1 contains at least one of a transition metal element other than Fe and Mn or a non-transition metal element.

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

[0101] Optionally, LiFe 1-x-y Mn x M 1 y PO4 is LiFePO4, LiMnPO4, LiFe 0.5 Mn 0.5 PO4. As such, the stability of the olivine structure material is relatively high, which is advantageous for improving the reliability of the battery cell.

[0102] In some embodiments, 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 <000\\038>includes at least one of Co, Ni, and Mn, and 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] ​​​​​​​​​​​​​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 that a thick first film layer 11 is advantageous for 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, the first film layer 11 provides more space for the second film layer 12, which is advantageous for 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 of 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, the thicknesses can be obtained by measuring the magnification of the scanning electron microscope and the size of the image obtained by the scanning electron microscope.

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

[0110] In this embodiment, by rationally setting the thickness of the first film layer 11, it is advantageous to achieve both high energy density and high reliability of the battery cell.

[0111] In some embodiments, the thickness d2 of the second membrane layer 12 is between 40 μm and 160 μm.

[0112] If the thickness d2 of the second membrane layer 12 is 40 μm or more, the gram capacity of the second active material is relatively high, so a thick second membrane layer 12 is advantageous for improving the energy density of the battery cell. If the thickness d2 of the second membrane layer 12 does not exceed 160 μm, more space can be provided for the first membrane layer when the volume of the battery cell is constant, which is advantageous for improving the reliability of the battery cell.

[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 of the battery cell.

[0114] Optionally, the thickness d2 of the second film layer 12 is 60 μm to 140 μm, which is advantageous in further achieving a balance between the reliability and energy density of the battery cell.

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

[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 adhesive strength 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 between the first active material and 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, by rationally setting the mass ratio between the second active material and the second film layer 12, it is advantageous to improve the overall performance of the second film layer 12, and to balance the energy density and reliability of the battery cell with the conductivity and adhesive strength of the second film layer 12.

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

[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, and 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 first active material or adhesive can be added to the first film layer 11, which is advantageous to improve the adhesive 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 adhesive 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, and 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 comprises at least one of superconducting carbon, conductive carbon black, Ketjen black, carbon dots, and carbon fibers, thereby facilitating flexible selection of the type of conductive agent according to actual circumstances.

[0124] In some embodiments, 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%, optionally 1.2 wt% to 1.4 wt%, for example 1.3 wt%, and / or 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 wt% to 2 wt%, optionally 1.2 wt% to 1.4 wt%, for example 1.3 wt%.

[0125] When the mass ratio of the adhesive to the first film layer 11 in the first film layer 11 is 1 wt% or more, it is advantageous to improve the adhesive performance of the first film layer 11, and when the mass ratio of the adhesive to the first film layer 11 in the first film layer 11 is 2 wt% or less, more 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 to the second film layer 12 in 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 to the second film layer 12 in 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, rationally setting the adhesive content in the first film layer 11 improves the adhesive strength between the first film layer 11 and the second film layer 12 or the positive electrode current collector 10, which is advantageous for reducing the risk of wrinkles in the positive electrode plate, and at the same time, is advantageous for achieving both the electrical conductivity of the first film layer 11 and the energy density and reliability of the battery cell. Rationally setting the adhesive content in the second film layer 12 improves the adhesive strength between the second film layer 12 and the first film layer 11 or the positive electrode current collector 10, which is advantageous for reducing the risk of wrinkles in the positive electrode plate, and at the same time, is advantageous for achieving both the electrical conductivity of the second film layer 12 and the energy density of the battery cell.

[0128] In the embodiments of the present 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 polyvinylidene fluoride, styrene polybutyl rubber, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, 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 of positive electrode plate] 4 is a schematic diagram of a method for manufacturing a positive electrode plate according to an embodiment of the present application. The embodiment of the present application provides a method for manufacturing a positive electrode plate, and as shown in FIG. 4, the method 200 includes the following steps:

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

[0132] In step 220, a first film layer 11 and a second film layer 12 are formed on the same side of at least one surface of the positive electrode current collector 10. Here, the first film layer 11 includes a first active material, which includes at least one of an olivine structure material and a spinel structure material, and the second film layer 12 includes a second active material, which includes 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 the positive electrode plate manufactured by this method is applied to a battery cell, it is advantageous to improve the performance of the battery cell.

[0134] [Battery cell] The present application provides a battery cell including the positive electrode plate described in the above examples.

[0135] The present application is not particularly limited to the shape of the battery cell, which may be cylindrical, rectangular, or any other shape.

[0136] 5 is a schematic diagram of a battery cell according to an embodiment of the present application. As shown in FIG. 5, the battery cell 4 includes a case 31, a cover plate 32, and an electrode assembly 33 disposed in the case 31.

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

[0138] Optionally, the battery cell 3 further includes an electrolyte. The electrolyte may be solid, semi-solid, or liquid, and the embodiments of the present application are not specifically limited thereto.

[0139] In some embodiments, the battery cells can be assembled into a battery module, and the number of battery cells included in the battery module can 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] 6 is a schematic diagram of a battery module according to one embodiment of the present application. Referring to FIG. 6, in a battery module 4, a plurality of battery cells 3 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of battery cells 3 may be fixed by fasteners.

[0141] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of battery cells 3 are accommodated in this accommodating space.

[0142] [battery] The present application provides a battery including the battery cell described in the above examples.

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

[0144] The battery cells 3 may directly constitute the battery 5, or may first constitute a battery module, which then constitutes the battery 5.

[0145] [Power consumption equipment] The present application provides a power consuming device that includes a battery as described in the above examples.

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

[0147] The following examples of the present application are described. The examples described below are illustrative and are used only to interpret the present application and should not be understood as limitations on the present application. Unless specific techniques or conditions are specified in the examples, they are carried out according to the techniques or conditions described in literature in the field or according to the product instructions. Unless the manufacturer is specified, the reagents or equipment used are all commercially available products.

[0148] [Example] Example 1 1 can be seen for the structure of the positive electrode plate in Example 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 was LiFePO4 (also referred to as LFP) with 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 contained a conductive agent, conductive carbon black, and an adhesive, polyvinylidene fluoride (PVDF). In 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%, based on the total weight of the first film layer 11.

[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 02 (also referred to as NCM), and the resistivity of the second active material was 4500 Ω·cm at 4 MPa. The second film layer 12 further contained a conductive agent, conductive carbon black, and an adhesive, PVDF. In 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%, based on the total weight of the second film layer 12.

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

[0152] Examples 2-7 The difference between Examples 2-7 and Example 1 is that R2 / R1 is different.

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

[0154] Examples 8-12 The difference between Examples 8-10 and Example 1 is that the values ​​of R1 and R2 are different.

[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 is that the thickness d1 of the first film layer 11 is different.

[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 is that the thickness d2 of the second film layer 12 is different.

[0163] In Examples 17-20, the thickness d2 of the first film layer 12 is 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 manganese iron phosphate LiFe 0.5 Mn 0.5 The reason 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 material is LiMn2O4 and LiFePO4, and the mass ratio between 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 reason is that it is O2 (abbreviated as LRNCM).

[0168] Examples 25-26 The difference between Examples 25 and 26 and Example 1 is the structure of the positive electrode plate 1. For the structure, refer to Figures 2 and 3.

[0169] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the structure in which the first film layer and the second film layer are stacked is not adopted.

[0170] In Comparative Example 1, LiFePO4 and LiNi 0.6 Co 0.2 Mn 0.2 O2 was mixed at a certain mass ratio, and then conductive carbon black, adhesive PVDF, and N-methylpyrrolidone (NMP) were added to prepare a positive electrode active slurry. The positive electrode active slurry was then applied to an aluminum foil and dried 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 powder of the first active material, R2 represents the resistivity of the powder of the second active material, 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] [Battery cell manufacturing] (1) Manufacturing of positive electrode plates Preparation of the first membrane layer slurry: The first active material, conductive agent, adhesive, and NMP were mixed and stirred to prepare a slurry. Preparation of the second membrane layer slurry: The second active material, conductive agent, adhesive, and NMP were mixed and stirred to prepare a slurry. Here, the types and blending ratios of the various materials in the first membrane layer slurry and the second membrane layer slurry are as shown in Tables 1 and 2.

[0175] The first and second film layer slurries were applied to the surface of the positive electrode current collector aluminum foil using an extrusion coating device, and then dried and cold pressed to obtain a positive electrode plate. 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, the conductive agent acetylene black, the adhesive styrene butadiene rubber, and the thickener sodium carboxymethyl cellulose were mixed in a weight ratio of graphite:acetylene black:styrene butadiene rubber:carboxymethyl cellulose sodium = 95:2:2:1, and 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 a negative electrode current collector copper foil, dried, and cold-pressed to obtain a negative electrode plate.

[0177] (3) Electrolyte production In a glove box under an argon gas atmosphere with a water content of <10 ppm, one or more solvents are mixed by weight to obtain a mixed solvent. A certain mass of fully dried lithium salt LiPF6 is dissolved in the mixed solvent, and then an inorganic lithium salt additive is added thereto and stirred uniformly to obtain an electrolyte solution.

[0178] (4) Battery cell manufacturing A positive electrode plate, a separator (a polyethylene porous polymer film), and a negative electrode plate are stacked in this order, with the separator positioned between the positive and negative electrodes to act as an insulator, and then wound up to obtain an electrode assembly. The electrode assembly is placed in a case, and the above-prepared electrolyte is injected into the case. The battery cell is then obtained through vacuum packaging, standing, chemical formation, and shaping processes.

[0179] [Determination of First Active Material and Second Active Material] A certain mass of active material layer is taken and a sample is prepared by polishing, tableting, etc., and an X-ray diffractometer is used to scan from 10 to 80 degrees at 5° / min. The type of active material can be identified by comparing the peaks with the characteristic peaks of the corresponding material.

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

[0181] [Cycle performance test] At 25°C / 45°C, the battery cell was first charged to 4.3V at a constant current of 1C, then further charged at a constant voltage of 4.3V until the current reached 0.05C, and then discharged to 3V at a constant current of 1C. This constitutes one charge-discharge cycle, and the discharge capacity in this cycle is the discharge capacity at the first cycle. The battery was subjected to multiple cycle charge-discharge tests using the above method, and the discharge capacity at the 200th cycle was measured and calculated using the following formula: Battery capacity retention after 200 cycles (wt%) = [Discharge capacity at 200th cycle / Discharge capacity at 1st cycle] × 100wt%.

[0182] [Nail penetration test] The battery core was charged to a full charge state, placed on a nail puncture sample stand, and punctured perpendicularly to the battery plate using a 3 mm steel needle at a speed of 1 mm / s until the puncture position approached the geometric center of the puncture surface, or until thermal runaway occurred.

[0183] In the examples of the present application, both the smoke-emitting valve opening and the lack of ignition and explosion indicate that the nail penetration test has been passed. In other words, it can be shown that the nail penetration test has been passed without explosion.

[0184] [Energy density test] At room temperature (25°C±2°C), discharge to the lower limit voltage using a constant current discharge method (1 / 3C rate), then leave it to stand for 30 minutes. Then, charge to the upper cut-off voltage using a constant current / constant voltage charge method (charge at a constant current of 1 / 3C and a constant voltage up to 1 / 20C), leave it to stand for 30 minutes, calculate the discharge energy E (calculated in Wh), repeat this three times, take the average of the three discharge energy E, and divide it 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 Examples 1-2, by disposing the first active material and the second active material in different film layers and ensuring that the resistivities of the first active material and the second active material satisfy a certain relationship, the early capacity fade of the battery cell can be improved, which is beneficial to improving the cycle performance of the battery cell and thereby the performance of the battery cell.

[0186] As shown in Examples 2-7, rationally setting the resistivity relationship between the first and second active materials can further reduce capacity fade during early cycling and improve the cycle performance of the battery cell. As shown in Examples 8-12, rationally setting the resistivity relationship between the first and second active materials can improve the cycle performance of the battery cell while facilitating the manufacture of the first and second active materials. As shown in Examples 13-20, rationally setting the thicknesses of the first and second film layers can facilitate flexible selection of the energy density, reliability, etc. of the battery cell according to actual conditions while improving the cycle performance of the battery cell. As shown in Examples 21-24, the technical solutions of the examples of the present application can be applied to multiple different active materials. As shown in Examples 25-26, the technical solutions of the examples of the present application can be applied to multiple positive electrode plate structures.

[0187] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea and achieves the same effects within the scope of the technical solution of the present application is included within the technical scope of the present application. In addition, various modifications that a person skilled in the art can make to the embodiments and other methods configured by combining some of the components of the embodiments are also included within the scope of the present application, as long as they do not deviate from the spirit of the present application.

Claims

1. A positive electrode plate, The positive electrode current collector (10) includes 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) includes a first active material, and the first active material includes at least one of a material with an olivine structure and a material with a spinel structure; the second membrane layer (12) comprises a second active material, the second active material comprising a layered structure material; 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.

2. 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 or 2, characterized in that 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.

4. 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. The positive electrode plate according to any one of claims 1 to 3.

5. The positive electrode plate according to any one of claims 1 to 4, characterized in that the second film layer (12) is located on a surface of the first film layer (11) away from the positive electrode current collector (10).

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

7. 7. The positive electrode plate according to claim 1, wherein the first active material includes a first active material core and a first coating layer coating the first active material core, the first active material core including at least one of the material with an olivine structure and the material with a spinel structure, and the first coating layer including a carbon material.

8. The olivine structure material is LiFe １－ｘ－ｙ Mn ｘ M １ ｙ P.O. ４ , where 0≦x≦1, 0≦y<1, 0≦x+y≦1, and M １ contains at least one of a transition metal element other than Fe and Mn or a non-transition metal element, and optionally, M １ contains at least one of Cr, Mg, Ti, Al, Zn, W, Nb, and Zr, and optionally, the LiFe １－ｘ－ｙ Mn ｘ M １ ｙ P.O. ４ is LiFePO ４ , LiMnPO ４ , LiFe ０．５ Mn ０．５ P.O. ４ The positive electrode plate according to any one of claims 1 to 7, comprising at least one of:

9. The spinel structure material is LiMn ２ O ４ , LiNi ｅ Mn ２－ｅ O ４ 9. The positive electrode plate according to claim 1, wherein 0<e<2.

10. The layered structure 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 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 any one of claims 1 to 9, characterized in that the positive electrode plate contains at least one of Co, Ni, and Mn.

11. The positive electrode plate according to any one of claims 1 to 10, characterized in that the thickness d1 of the first membrane layer (11) is between 40 μm and 160 μm, and optionally between 60 μm and 140 μm.

12. The positive electrode plate according to any one of claims 1 to 11, characterized in that the thickness d2 of the second membrane layer (12) is between 40 μm and 160 μm, and optionally between 60 μm and 140 μm.

13. 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 optionally 96 wt % to 98 wt %; and / or 13. The positive electrode plate according to claim 1, wherein the weight percentage content of the second active material is 90 wt % to 99 wt %, and optionally 96 wt % to 98 wt %, based on the total weight of the second membrane layer (12).

14. Based on the total weight of the first membrane layer (11), the weight percentage content of the conductive agent in the first membrane layer (11) is 0.1 wt% to 1 wt%, optionally 0.3 wt% to 0.6 wt%; and / or 14. The positive electrode plate according to claim 1, wherein the weight percentage content of the conductive agent in the second membrane layer (12) is 0.1 wt % to 1 wt %, and optionally 0.3 wt % to 0.6 wt %, based on the total weight of the second membrane layer (12).

15. The positive electrode plate according to claim 14 , wherein the conductive agent comprises at least one of superconducting carbon, conductive carbon black, ketjen black, carbon dots, and carbon fibers.

16. 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 optionally 1.2 wt% to 1.4 wt%; and / or 16. The positive electrode plate according to any one of claims 1 to 15, characterized in that, 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 wt% to 2 wt%, and optionally 1.2 wt% to 1.4 wt%.

17. 17. The positive electrode plate of claim 16, wherein the adhesive includes 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.

18. A method for manufacturing a positive electrode plate, Providing a positive electrode current collector (10); and forming a first membrane layer (11) and a second membrane layer (12) on the same side of at least one surface of the positive electrode current collector (10), wherein: The first film layer (11) includes a first active material, and the first active material includes at least one of a material with an olivine structure and a material with a spinel structure; the second membrane layer (12) comprises a second active material, the second active material comprising a layered structure material; A method for producing 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.

19. A battery cell comprising the positive electrode plate according to any one of claims 1 to 17.

20. A battery comprising the battery cell of claim 19.

21. 21. A power consuming device comprising the battery of claim 20.

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