Negative plate, positive plate, battery and electric equipment

Abstract

The invention discloses a negative electrode plate, a positive electrode plate, a battery and electric equipment, the negative electrode plate comprises a negative electrode active material layer, the negative electrode active material layer comprises a first area negative electrode active material layer and a second area negative electrode active material layer, the first area negative electrode active material layer is arranged on the edge of at least one side of the second area negative electrode active material layer along the width direction, and the first area negative electrode active material layer comprises a first negative electrode dressing layer and a second negative electrode dressing layer which are laminated along the thickness direction. The active specific surface area of the first negative electrode active material is larger than the active specific surface area of the second negative electrode active material and is larger than or equal to the active specific surface area of the third negative electrode active material; the lithium ion diffusivity of the first area negative electrode active material layer in the edge area of the negative electrode plate is better than that of the second area negative electrode active material layer in the central area, so that the lithium intercalation capacity of the edge area of the negative electrode plate is enhanced, and the edge lithium precipitation problem of the electrode plate is reduced.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and specifically relates to a negative electrode sheet, a positive electrode sheet, a battery and an electrical device. Background Art

[0002] In the design of the electrode sheet of a lithium-ion battery, the negative electrode sheet should be wider than the positive electrode sheet in consideration of the assembly tolerance. The area where the negative electrode sheet exceeds the positive electrode sheet is called the overhang area. During the charging process of a lithium-ion battery, lithium ions are released from the positive electrode and embedded in the negative electrode through the electrolyte and the separator. When charging is completed, the negative electrode overhang area is not completely lithiated, and a gradient distribution of lithium is formed at the edge of the negative electrode. During the subsequent storage process, the lithium ions will migrate laterally from the negative electrode lithium embedding center to the overhang area; after the discharge is completed, there are still unde-embedded lithium ions in the overhang area, indicating that during the discharge process, the edge of the positive electrode sheet not only receives lithium ions from the negative electrode area facing it, but also receives lithium de-embedded from the negative electrode overhang area. As the number of cycles increases, the lithium ion concentration at the edge of the positive electrode sheet becomes higher and higher, exceeding the negative electrode lithium embedding capacity, resulting in lithium deposition at the edge of the negative electrode during subsequent charging.

[0003] Currently, conventional electrodes are generally single-layer coated, with the same dressing used for the edge and middle layer, and the lithium ion diffusion capacity is consistent. However, the electrode structure does not take into account the difference in lithium ion concentration between the edge and the middle area of ​​the electrode. During long-term cycling, lithium deposition is likely to occur first at the edge of the electrode, especially during fast charging. The occurrence of lithium deposition will continue to deteriorate the battery's cycle performance and safety performance. Summary of the invention

[0004] The present application aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the purpose of the present application is to propose a negative electrode sheet, a positive electrode sheet, a battery and an electrical device. The lithium ion diffusion capacity of the negative electrode active material layer in the first region of the edge region of the negative electrode sheet of the present application is better than the lithium ion diffusion capacity of the negative electrode active material layer in the second region of the central region, which enhances the lithium insertion capacity of the edge region of the negative electrode sheet, thereby reducing the problem of lithium deposition at the edge of the electrode sheet, which is beneficial to ensure the cycle performance and safety performance of the battery.

[0005] In one aspect of the present application, the present application provides a negative electrode sheet. According to an embodiment of the present application, the negative electrode sheet includes:

[0006] Anode current collector;

[0007] A negative electrode active material layer, wherein the negative electrode active material layer is disposed on at least a portion of the surface of the negative electrode collector, the negative electrode active material layer comprises a first region negative electrode active material layer and a second region negative electrode active material layer, the first region negative electrode active material layer is disposed on at least one side edge of the second region negative electrode active material layer in the width direction, the first region negative electrode active material layer comprises a first negative electrode dressing layer and a second negative electrode dressing layer stacked in the thickness direction, and the second negative electrode dressing layer is disposed on the surface of the negative electrode collector, and the first negative electrode dressing layer is disposed on the surface of the first negative electrode dressing layer away from the negative electrode collector;

[0008] The first negative electrode dressing layer includes a first negative electrode active material, the second negative electrode dressing layer includes a second negative electrode active material, the second regional negative electrode active material layer includes a third negative electrode active material, and the active specific surface area of ​​the first negative electrode active material is greater than the active specific surface area of ​​the second negative electrode active material and greater than the active specific surface area of ​​the third negative electrode active material.

[0009] According to the negative electrode sheet of the embodiment of the present application, by limiting the active specific surface area of ​​the first negative electrode active material> the active specific surface area of ​​the second negative electrode active material≥ the active specific surface area of ​​the third negative electrode active material, the lithium ion diffusion capacity of the negative electrode active material layer in the first region of the edge region of the negative electrode sheet is better than the lithium ion diffusion capacity of the negative electrode active material layer in the second region of the central region, and the lithium insertion capacity of the edge region of the negative electrode sheet is enhanced, thereby reducing the current accumulation effect of the edge of the electrode sheet during the charging and discharging process, thereby reducing the accumulation of lithium ions at the edge of the electrode sheet caused by the current accumulation effect, and reducing the problem of lithium precipitation at the edge of the electrode sheet, which is conducive to ensuring the cycle performance and safety performance of the battery. At the same time, by limiting the active specific surface area of ​​the first negative electrode active material of the first negative electrode dressing layer (i.e., the edge surface layer) to be greater than the active specific surface area of ​​the second negative electrode active material of the second negative electrode dressing layer (edge ​​bottom layer), it is conducive to the rapid deintercalation of lithium ions in the edge surface layer, which is further conducive to reducing the problem of lithium precipitation at the edge of the electrode sheet, especially to reducing the problem of lithium precipitation at the edge that is prone to occur during fast charging.

[0010] In addition, the negative electrode sheet according to the above embodiment of the present application may also have the following additional technical features:

[0011] In some embodiments of the present application, the ratio of the active specific surface area of ​​the first negative electrode active material to the active specific surface area of ​​the second negative electrode active material is 1.05-2.5; and / or the ratio of the active specific surface area of ​​the first negative electrode active material to the active specific surface area of ​​the third negative electrode active material is 1.05-3.

[0012] In some embodiments of the present application, the gram capacity of the first negative electrode active material>the gram capacity of the second negative electrode active material≥the gram capacity of the third negative electrode active material.

[0013] In some embodiments of the present application, the ratio of the gram capacity of the first negative electrode active material to the gram capacity of the second negative electrode active material is 1.005-1.03; and / or the ratio of the gram capacity of the first negative electrode active material to the gram capacity of the third negative electrode active material is 1.01-1.05.

[0014] In some embodiments of the present application, the first negative electrode dressing layer also includes a first negative electrode conductive agent, the second negative electrode dressing layer also includes a second negative electrode conductive agent, the second region negative electrode active material layer also includes a third negative electrode conductive agent, and the resistivity of the first negative electrode conductive agent is less than the resistivity of the second negative electrode conductive agent and less than the resistivity of the third negative electrode conductive agent.

[0015] In some embodiments of the present application, the ratio of the resistivity of the second negative electrode conductive agent to the resistivity of the first negative electrode conductive agent is 1.5-4; and / or the ratio of the resistivity of the third negative electrode conductive agent to the resistivity of the first negative electrode conductive agent is 4-9.

[0016] In some embodiments of the present application, the content of the first negative electrode conductive agent in the first negative electrode dressing layer>the content of the second negative electrode conductive agent in the second negative electrode dressing layer≥the content of the third negative electrode conductive agent in the second region negative electrode active material layer.

[0017] In some embodiments of the present application, the ratio of the content of the first negative electrode conductive agent in the first negative electrode dressing layer to the content of the second negative electrode conductive agent in the second negative electrode dressing layer is 1.01 to 2; and / or the ratio of the content of the first negative electrode conductive agent in the first negative electrode dressing layer to the content of the third negative electrode conductive agent in the second region negative electrode active material layer is 1.03 to 2.

[0018] In some embodiments of the present application, the first negative electrode dressing layer also includes a first negative electrode binder, the second negative electrode dressing layer also includes a second negative electrode binder, the second region negative electrode active material layer also includes a third negative electrode binder, and the content of the first negative electrode binder in the first negative electrode dressing layer is less than the content of the second negative electrode binder in the second negative electrode dressing layer and less than or equal to the content of the third negative electrode binder in the second region negative electrode active material layer.

[0019] In some embodiments of the present application, the ratio of the content of the second negative electrode binder in the second negative electrode dressing layer to the content of the first negative electrode binder in the first negative electrode dressing layer is 1.005-1.5; and / or, the ratio of the content of the third negative electrode binder in the second region negative electrode active material layer to the content of the first negative electrode binder in the first negative electrode dressing layer is 1.005-2.

[0020] In some embodiments of the present application, the capacity per unit area of ​​the negative electrode active material layer in the second region is ≤ the capacity per unit area of ​​the first negative electrode dressing layer + the capacity per unit area of ​​the second negative electrode dressing layer.

[0021] In some embodiments of the present application, the surface density of the negative electrode active material layer in the second region = the surface density of the first negative electrode dressing layer + the surface density of the second negative electrode dressing layer.

[0022] In some embodiments of the present application, the ratio of the thickness of the first negative electrode dressing layer to the thickness of the second negative electrode dressing layer is 5:(1-8); and / or the width W1 of the negative electrode active material layer in the first region on one side is smaller than the width W2 of the negative electrode active material layer in the second region.

[0023] In a second aspect of the present application, the present application proposes a positive electrode sheet. According to an embodiment of the present application, the positive electrode sheet includes:

[0024] Positive electrode current collector;

[0025] A positive electrode active material layer, wherein the positive electrode active material layer is disposed on at least a portion of the surface of the positive electrode collector, the positive electrode active material layer comprises a first region positive electrode active material layer and a second region positive electrode active material layer, the first region positive electrode active material layer is disposed on at least one side edge of the second region positive electrode active material layer in a width direction, the first region positive electrode active material layer comprises a first positive electrode dressing layer and a second positive electrode dressing layer stacked in a thickness direction, and the second positive electrode dressing layer is disposed on the surface of the positive electrode collector, and the first positive electrode dressing layer is disposed on a surface of the first positive electrode dressing layer away from the positive electrode collector;

[0026] The first positive electrode dressing layer includes a first positive electrode active material, the second positive electrode dressing layer includes a second positive electrode active material, the second region positive electrode active material layer includes a third positive electrode active material, and the active specific surface area of ​​the first positive electrode active material is less than the active specific surface area of ​​the second positive electrode active material and less than the active specific surface area of ​​the third positive electrode active material.

[0027] According to the positive electrode sheet of the embodiment of the present application, by limiting the active specific surface area of ​​the first positive electrode active material to be less than the active specific surface area of ​​the second positive electrode active material ≤ the active specific surface area of ​​the third positive electrode active material, the lithium ion diffusion capacity of the positive electrode active material layer in the first region of the edge region of the positive electrode sheet is weaker than the lithium ion diffusion capacity of the positive electrode active material layer in the second region of the central region, and the lithium removal capacity of the edge region of the positive electrode sheet is reduced, thereby reducing the current accumulation effect of the edge of the electrode sheet during the charge and discharge process, thereby reducing the accumulation of lithium ions at the edge of the corresponding negative electrode caused by the current accumulation effect, and reducing the problem of lithium precipitation at the edge of the corresponding negative electrode, which is conducive to ensuring the cycle performance and safety performance of the battery. At the same time, by limiting the active specific surface area of ​​the first positive electrode active material of the first positive electrode dressing layer (i.e., the edge surface layer) to be less than the active specific surface area of ​​the second positive electrode active material of the second positive electrode dressing layer (edge ​​bottom layer), it is conducive to the slow deintercalation of lithium ions in the edge surface layer, which is further conducive to reducing the problem of lithium precipitation at the edge of the corresponding negative electrode, especially conducive to reducing the problem of lithium precipitation at the edge that is prone to occur during fast charging.

[0028] In addition, the positive electrode sheet according to the above embodiment of the present application may also have the following additional technical features:

[0029] In some embodiments of the present application, the ratio of the active specific surface area of ​​the second positive electrode active material to the active specific surface area of ​​the first positive electrode active material is 1.05-4.5; and / or the ratio of the active specific surface area of ​​the third positive electrode active material to the active specific surface area of ​​the first positive electrode active material is 1.05-5.

[0030] In some embodiments of the present application, the gram capacity of the first positive electrode active material is less than the gram capacity of the second positive electrode active material and less than the gram capacity of the third positive electrode active material.

[0031] In some embodiments of the present application, the ratio of the gram capacity of the second positive electrode active material to the gram capacity of the first positive electrode active material is 1.005-1.03; and / or the ratio of the gram capacity of the third positive electrode active material to the gram capacity of the first positive electrode active material is 1.01-1.06.

[0032] In some embodiments of the present application, the first positive electrode dressing layer also includes a first positive electrode conductive agent, the second positive electrode dressing layer also includes a second positive electrode conductive agent, the second region positive electrode active material layer also includes a third positive electrode conductive agent, and the resistivity of the first positive electrode conductive agent is greater than the resistivity of the second positive electrode conductive agent and greater than the resistivity of the third positive electrode conductive agent.

[0033] In some embodiments of the present application, the ratio of the resistivity of the first positive electrode conductor to the resistivity of the second positive electrode conductor is 1.2-4; and / or the ratio of the resistivity of the first positive electrode conductor to the resistivity of the third positive electrode conductor is 2-6.

[0034] In some embodiments of the present application, the content of the first positive electrode conductive agent in the first positive electrode dressing layer is less than the content of the second positive electrode conductive agent in the second positive electrode dressing layer and is less than or equal to the content of the third positive electrode conductive agent in the second region positive active material layer.

[0035] In some embodiments of the present application, the ratio of the content of the second positive electrode conductive agent in the second positive electrode dressing layer to the content of the first positive electrode conductive agent in the first positive electrode dressing layer is 1.01 to 2; and / or the ratio of the content of the third positive electrode conductive agent in the second region positive active material layer to the content of the first positive electrode conductive agent in the first positive electrode dressing layer is 1.03 to 2.

[0036] In some embodiments of the present application, the first positive electrode dressing layer also includes a first positive electrode binder, the second positive electrode dressing layer also includes a second positive electrode binder, and the second-region positive electrode active material layer also includes a third positive electrode binder, and the content of the first positive electrode binder in the first positive electrode dressing layer is greater than the content of the second positive electrode binder in the second positive electrode dressing layer and greater than the content of the third positive electrode binder in the second-region positive electrode active material layer.

[0037] In some embodiments of the present application, the ratio of the content of the first positive electrode binder in the first positive electrode dressing layer to the content of the second positive electrode binder in the second positive electrode dressing layer is 1.005 to 1.5; and / or the ratio of the content of the first positive electrode binder in the first positive electrode dressing layer to the content of the third positive electrode binder in the second region positive electrode active material layer is 1.005 to 2.

[0038] In some embodiments of the present application, the capacity per unit area of ​​the positive electrode active material layer in the second region is ≥ the capacity per unit area of ​​the first positive electrode dressing layer + the capacity per unit area of ​​the second positive electrode dressing layer.

[0039] In some embodiments of the present application, the surface density of the positive electrode active material layer in the second region = the surface density of the first positive electrode dressing layer + the surface density of the second positive electrode dressing layer.

[0040] In some embodiments of the present application, the ratio of the thickness of the first positive electrode dressing layer to the thickness of the second positive electrode dressing layer is 5:(1-8); and / or the width W1' of the first region positive electrode active material layer on one side is smaller than the width W2' of the second region positive electrode active material layer.

[0041] In the third aspect of the present application, the present application proposes a battery. According to an embodiment of the present application, the battery has the negative electrode sheet described in the above embodiment and / or the positive electrode sheet described in the above embodiment. As a result, the problem of lithium deposition at the edge of the negative electrode sheet is effectively reduced, which is conducive to ensuring the cycle performance and safety performance of the battery.

[0042] In some embodiments of the present application, the width of the negative electrode sheet on one side exceeding the positive electrode sheet on the same side is W0, the width W1 of the negative electrode active material layer in the first region on one side satisfies W0+2≤W1≤W0+6mm; the width W1' of the positive electrode active material layer in the first region on one side satisfies W0+2≤W1'≤W0+6mm.

[0043] In the fourth aspect of the present application, the present application proposes an electric device. According to an embodiment of the present application, the electric device has the battery described in the above embodiment. Therefore, the electric device has all the advantages of the battery, which will not be repeated here.

[0044] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0046] Figure 1 A schematic diagram of the structure of the negative electrode sheet of an embodiment of the present application;

[0047] Figure 2 A schematic diagram of the structure of the positive electrode sheet of an embodiment of the present application;

[0048] Figure 3 Schematic diagram of the structure of the battery of the embodiment of the present application.

[0049] Reference numerals:

[0050] 100-negative electrode sheet, 110-first region negative electrode active material layer, 111-first negative electrode dressing layer, 112-second negative electrode dressing layer, 120-second region negative electrode active material layer, 130-negative electrode collector, 200-positive electrode sheet, 210-first region positive electrode active material layer, 211-first positive electrode dressing layer, 212-second positive electrode dressing layer, 220-second region positive electrode active material layer, 230-positive electrode collector, 300-separator. DETAILED DESCRIPTION

[0051] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0052] In one aspect of the present application, the present application provides a negative electrode sheet 100. According to an embodiment of the present application, referring to the attached Figure 1 The negative electrode sheet 100 includes: a negative electrode current collector 130; a negative electrode active material layer, the negative electrode active material layer is arranged on at least a portion of the surface of the negative electrode current collector 130, the negative electrode active material layer includes a first region negative electrode active material layer 110 and a second region negative electrode active material layer 120, the first region negative electrode active material layer 110 is arranged on at least one side edge of the second region negative electrode active material layer 120 along the width direction, the first region negative electrode active material layer 110 includes a first negative electrode dressing layer 111 and a second negative electrode dressing layer 112 stacked along the thickness direction. 2, and the second negative electrode dressing layer 112 is arranged on the surface of the negative electrode collector 130, and the first negative electrode dressing layer 111 is arranged on the surface of the first negative electrode dressing layer 111 away from the negative electrode collector 130; the first negative electrode dressing layer 111 includes a first negative electrode active material, the second negative electrode dressing layer 112 includes a second negative electrode active material, and the second regional negative electrode active material layer 120 includes a third negative electrode active material, and the active specific surface area of ​​the first negative electrode active material is greater than the active specific surface area of ​​the second negative electrode active material and greater than the active specific surface area of ​​the third negative electrode active material.

[0053] The beneficial effects that can be achieved by the negative electrode sheet proposed in this application are described in detail below:

[0054] The negative electrode active material layer of the present application includes a first region negative electrode active material layer in the edge region and a second region negative electrode active material layer in the center region, and the first region negative electrode active material layer includes a first negative electrode dressing layer on the surface and a second negative electrode dressing layer on the bottom layer. The present application limits the active specific surface area of ​​the first negative electrode active material>the active specific surface area of ​​the second negative electrode active material≥the active specific surface area of ​​the third negative electrode active material, so that the lithium ion diffusion capacity of the first region negative electrode active material layer in the edge region of the negative electrode sheet is better than the lithium ion diffusion capacity of the second region negative electrode active material layer in the center region, and enhances the lithium insertion capacity of the edge region of the negative electrode sheet, thereby reducing the current accumulation effect at the edge of the electrode sheet during the charge and discharge process, thereby reducing the accumulation of lithium ions at the edge of the electrode sheet caused by the current accumulation effect, and reducing the problem of lithium precipitation at the edge of the electrode sheet, which is beneficial to ensure the cycle performance and safety performance of the battery. At the same time, by limiting the active specific surface area of ​​the first negative electrode active material of the first negative electrode dressing layer (i.e., the edge surface layer) to be greater than the active specific surface area of ​​the second negative electrode active material of the second negative electrode dressing layer (edge ​​bottom layer), it is beneficial to the rapid deintercalation of lithium ions in the edge surface layer, and further beneficial to reducing the problem of lithium plating at the edge of the electrode piece, especially beneficial to reducing the problem of lithium plating at the edge that is prone to occur during fast charging.

[0055] According to some specific embodiments of the present application, the ratio of the active specific surface area of ​​the first negative electrode active material to the active specific surface area of ​​the second negative electrode active material is 1.05 to 2.5, and as an example, it can be 1.05 / 1.1 / 1.2 / 1.4 / 1.6 / 1.8 / 2 / 2.2 / 2.5, etc.; and / or, the ratio of the active specific surface area of ​​the first negative electrode active material to the active specific surface area of ​​the third negative electrode active material is 1.05 to 3, and as an example, it can be 1.05 / 1.1 / 1.2 / 1.4 / 1.6 / 1.8 / 2 / 2.2 / 2.4 / 2.6 / 2.8 / 3, etc. Thus, it is further beneficial to reduce the problem of lithium deposition at the edge of the pole piece, and further beneficial to the rapid deintercalation of lithium ions at the edge surface.

[0056] According to some other specific embodiments of the present application, the gram capacity of the first negative electrode active material> the gram capacity of the second negative electrode active material≥ the gram capacity of the third negative electrode active material, thereby enabling the first region of the negative electrode active material layer in the edge region of the negative electrode sheet to have a better reception capacity for lithium ions than the second region of the negative electrode active material layer in the center region, thereby effectively reducing the accumulation of lithium ions at the edge of the electrode sheet and reducing the problem of lithium precipitation at the edge of the electrode sheet. At the same time, the edge surface layer can have a better reception capacity for lithium ions than the edge bottom layer, further facilitating the deintercalation of lithium ions at the edge surface layer, thereby further facilitating the reduction of lithium precipitation at the edge of the electrode sheet.

[0057] According to some other specific embodiments of the present application, the ratio of the gram capacity of the first negative electrode active material to the gram capacity of the second negative electrode active material is 1.005-1.03, and as an example, it can be 1.005 / 1.01 / 1.015 / 1.02 / 1.025 / 1.03, etc.; and / or, the ratio of the gram capacity of the first negative electrode active material to the gram capacity of the third negative electrode active material is 1.01-1.05, and as an example, it can be 1.01 / 1.015 / 1.02 / 1.025 / 1.03 / 1.035 / 1.04 / 1.045 / 1.05, etc. Thus, it is further beneficial to reduce the accumulation of lithium ions at the edge of the pole piece, thereby further helping to reduce the problem of lithium deposition at the edge of the pole piece.

[0058] In the embodiments of the present application, the specific types of the above-mentioned first negative electrode active material, the second negative electrode active material and the third negative electrode active material are not particularly limited, and those skilled in the art can select them according to actual needs. As some preferred embodiments, the above-mentioned first negative electrode active material, the second negative electrode active material and the third negative electrode active material respectively include at least one of artificial graphite, natural graphite, hard carbon, soft carbon, and silicon-based negative electrode materials.

[0059] In the embodiments of the present application, different types of negative electrode active materials can be used to adjust the active specific surface area or gram capacity of the first negative electrode active material, the second negative electrode active material and the third negative electrode active material. The same type of active material can also be used to adjust the active specific surface area or gram capacity of the first negative electrode active material, the second negative electrode active material and the third negative electrode active material by mixing the same type of active material with different particle sizes, voids or morphologies. For example, if the same type of negative electrode active material artificial graphite has different particle sizes, voids or morphologies, it will result in different active specific surface areas or gram capacities.

[0060] According to some other specific embodiments of the present application, the first negative electrode dressing layer also includes a first negative electrode conductive agent, the second negative electrode dressing layer also includes a second negative electrode conductive agent, and the second region negative electrode active material layer also includes a third negative electrode conductive agent, and the resistivity of the first negative electrode conductive agent is less than the resistivity of the second negative electrode conductive agent and less than the resistivity of the third negative electrode conductive agent. Thus, the lithium ion diffusion rate of the first region negative electrode active material layer in the edge region of the negative electrode sheet can be made better than the lithium ion diffusion rate of the second region negative electrode active material layer in the central region, thereby effectively reducing the accumulation of lithium ions at the edge of the electrode sheet and reducing the problem of lithium precipitation at the edge of the electrode sheet. At the same time, the lithium ion diffusion rate of the edge surface layer can be made better than the lithium ion diffusion rate of the edge bottom layer, which is further beneficial to the deintercalation of lithium ions in the edge surface layer, thereby further helping to reduce the problem of lithium precipitation at the edge of the electrode sheet. It can be understood that the conductive agent can increase the specific surface area of ​​the electrode and increase the contact area between lithium ions and the electrode material, thereby reducing the diffusion path of lithium ions and increasing the diffusion rate of lithium ions.

[0061] According to some other specific embodiments of the present application, the ratio of the resistivity of the second negative electrode conductive agent to the resistivity of the first negative electrode conductive agent is 1.5 to 4, and as an example, it can be 1.5 / 2 / 2.5 / 3 / 3.5 / 4, etc.; and / or, the ratio of the resistivity of the third negative electrode conductive agent to the resistivity of the first negative electrode conductive agent is 4 to 9, and as an example, it can be 4 / 5 / 6 / 7 / 8 / 9, etc. This is further conducive to reducing the accumulation of lithium ions at the edge of the pole piece, thereby further helping to reduce the problem of lithium deposition at the edge of the pole piece.

[0062] According to some other specific embodiments of the present application, the content of the first negative electrode conductive agent in the first negative electrode dressing layer is greater than the content of the second negative electrode conductive agent in the second negative electrode dressing layer, and greater than or equal to the content of the third negative electrode conductive agent in the second region negative electrode active material layer. As a result, the lithium ion diffusion rate of the first region negative electrode active material layer in the edge region of the negative electrode sheet can be further made better than the lithium ion diffusion rate of the second region negative electrode active material layer in the center region, thereby effectively reducing the accumulation of lithium ions at the edge of the electrode sheet and reducing the problem of lithium deposition at the edge of the electrode sheet. At the same time, the lithium ion diffusion rate of the edge surface layer can be further made better than the lithium ion diffusion rate of the edge bottom layer, which is further beneficial to the deintercalation of lithium ions on the edge surface layer, thereby further helping to reduce the problem of lithium deposition at the edge of the electrode sheet.

[0063] According to some other specific embodiments of the present application, the ratio of the content of the first negative electrode conductive agent in the first negative electrode dressing layer to the content of the second negative electrode conductive agent in the second negative electrode dressing layer is 1.01-2, and as an example, it can be 1.01 / 1.02 / 1.05 / 1.1 / 1.2 / 1.3 / 1.4 / 1.5 / 1.6 / 1.7 / 1.8 / 1.9 / 2, etc.; and / or, the ratio of the content of the first negative electrode conductive agent in the first negative electrode dressing layer to the content of the third negative electrode conductive agent in the second region negative electrode active material layer is 1.03-2, and as an example, it can be 1.03 / 1.05 / 1.1 / 1.2 / 1.3 / 1.4 / 1.5 / 1.6 / 1.7 / 1.8 / 1.9 / 2, etc. Thus, it is further beneficial to reduce the accumulation of lithium ions at the edge of the pole piece, thereby further helping to reduce the problem of lithium deposition at the edge of the pole piece.

[0064] In the embodiments of the present application, the specific types of the first negative electrode conductive agent, the second negative electrode conductive agent and the third negative electrode conductive agent are not particularly limited, and those skilled in the art can select them according to actual needs. As some preferred embodiments, the first negative electrode conductive agent, the second negative electrode conductive agent and the third negative electrode conductive agent respectively include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0065] In the embodiment of the present application, different types of negative electrode conductive agents can be used to adjust the resistivity of the first negative electrode conductive agent, the second negative electrode conductive agent and the third negative electrode conductive agent, or the same type of negative electrode conductive agent can be used to adjust the resistivity of the first negative electrode conductive agent, the second negative electrode conductive agent and the third negative electrode conductive agent by mixing the same type of conductive agents with different particle sizes, voids or morphologies. For example, the same type of negative electrode conductive agent carbon black, with different particle sizes, voids or morphologies, will result in different resistivities.

[0066] According to some other specific embodiments of the present application, the first negative electrode dressing layer also includes a first negative electrode binder, the second negative electrode dressing layer also includes a second negative electrode binder, and the second-region negative electrode active material layer also includes a third negative electrode binder, and the content of the first negative electrode binder in the first negative electrode dressing layer is less than the content of the second negative electrode binder in the second negative electrode dressing layer and less than the content of the third negative electrode binder in the second-region negative electrode active material layer. Thus, the lithium ion diffusion rate of the first-region negative electrode active material layer in the edge region of the negative electrode sheet can be further made better than the lithium ion diffusion rate of the second-region negative electrode active material layer in the center region, thereby effectively reducing the accumulation of lithium ions at the edge of the electrode sheet and reducing the problem of lithium precipitation at the edge of the electrode sheet. At the same time, the lithium ion diffusion rate of the edge surface layer can be further made better than the lithium ion diffusion rate of the edge bottom layer, which is further beneficial to the deintercalation of lithium ions on the edge surface layer, thereby further beneficial to reducing the problem of lithium precipitation at the edge of the electrode sheet.

[0067] According to some other specific embodiments of the present application, the ratio of the content of the second negative electrode binder in the second negative electrode dressing layer to the content of the first negative electrode binder in the first negative electrode dressing layer is 1.005-1.5, and as an example, it can be 1.005 / 1.01 / 1.03 / 1.05 / 1.1 / 1.2 / 1.3 / 1.5, etc.; and / or, the ratio of the content of the third negative electrode binder in the second region negative electrode active material layer to the content of the first negative electrode binder in the first negative electrode dressing layer is 1.005-2, and as an example, it can be 1.005 / 1.01 / 1.03 / 1.05 / 1.1 / 1.2 / 1.3 / 1.4 / 1.5 / 1.6 / 1.7 / 1.8 / 1.9 / 2, etc. Thus, it is further beneficial to reduce the accumulation of lithium ions at the edge of the pole piece, thereby further helping to reduce the problem of lithium deposition at the edge of the pole piece.

[0068] In the embodiments of the present application, the specific types of the first negative electrode binder, the second negative electrode binder and the third negative electrode binder are not particularly limited, and those skilled in the art can select them according to actual needs. As some preferred embodiments, the first negative electrode binder, the second negative electrode binder and the third negative electrode binder respectively include at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

[0069] According to some other specific embodiments of the present application, the capacity per unit area of ​​the negative electrode active material layer in the second region is ≤ the capacity per unit area of ​​the first negative electrode dressing layer + the capacity per unit area of ​​the second negative electrode dressing layer, thereby further ensuring that the negative electrode active material layer in the first region in the edge region has better lithium ion reception capacity than the negative electrode active material layer in the second region in the center region, thereby effectively reducing the accumulation of lithium ions at the edge of the electrode piece and reducing the problem of lithium plating at the edge of the electrode piece.

[0070] According to some other specific embodiments of the present application, the surface density of the negative electrode active material layer in the second region = the surface density of the first negative electrode dressing layer + the surface density of the second negative electrode dressing layer, thereby further ensuring that the lithium ion diffusion capacity of the negative electrode active material layer in the first region in the edge region is better than the lithium ion diffusion capacity of the negative electrode active material layer in the second region in the center region, further reducing the problem of lithium plating at the edge of the electrode sheet.

[0071] According to some other specific embodiments of the present application, the thickness ratio of the first negative electrode dressing layer to the second negative electrode dressing layer is 5:(1-8), and as an example, it can be 5:1, 5:2, 5:3, 5:4, 5:5, 5:6, 5:7, 5:8, etc.; and / or, the width W1 of the negative electrode active material layer in the first region on one side is smaller than the width W2 of the negative electrode active material layer in the second region. Thus, the problem of lithium deposition at the edge of the pole piece can be further reduced.

[0072] In the second aspect of the present application, the present application provides a positive electrode sheet 200. According to the embodiment of the present application, refer to the attached Figure 2The positive electrode sheet 200 includes: a positive electrode current collector 230; a positive electrode active material layer, the positive electrode active material layer is arranged on at least part of the surface of the positive electrode current collector 230, the positive electrode active material layer includes a first region positive electrode active material layer 210 and a second region positive electrode active material layer 220, the first region positive electrode active material layer 210 is arranged on at least one side edge of the second region positive electrode active material layer 220 along the width direction, the first region positive electrode active material layer 210 includes a first positive electrode dressing layer 211 and a second positive electrode dressing layer 212 stacked in the thickness direction. 2, and the second positive electrode dressing layer 212 is arranged on the surface of the positive electrode collector 230, and the first positive electrode dressing layer 211 is arranged on the surface of the first positive electrode dressing layer 211 away from the positive electrode collector 230; the first positive electrode dressing layer 211 includes a first positive electrode active material, the second positive electrode dressing layer 212 includes a second positive electrode active material, and the second region positive electrode active material layer 220 includes a third positive electrode active material, and the active specific surface area of ​​the first positive electrode active material is less than the active specific surface area of ​​the second positive electrode active material and less than the active specific surface area of ​​the third positive electrode active material.

[0073] The beneficial effects that can be achieved by the positive electrode sheet proposed in this application are described in detail below:

[0074] The positive electrode active material layer of the present application includes a first region positive electrode active material layer in the edge region and a second region positive electrode active material layer in the center region, and the first region positive electrode active material layer includes a first positive electrode dressing layer on the surface and a second positive electrode dressing layer on the bottom layer. The present application limits the active specific surface area of ​​the first positive electrode active material to < the active specific surface area of ​​the second positive electrode active material ≤ the active specific surface area of ​​the third positive electrode active material, so that the lithium ion diffusion capacity of the first region positive electrode active material layer in the edge region of the positive electrode sheet is weaker than the lithium ion diffusion capacity of the second region positive electrode active material layer in the center region, thereby reducing the lithium delithiation capacity of the edge region of the positive electrode sheet, thereby reducing the current accumulation effect at the edge of the electrode sheet during the charge and discharge process, thereby reducing the accumulation of lithium ions at the edge of the corresponding negative electrode caused by the current accumulation effect, and reducing the problem of lithium deposition at the edge of the corresponding negative electrode, which is beneficial to ensuring the cycle performance and safety performance of the battery. At the same time, by limiting the active specific surface area of ​​the first positive electrode active material of the first positive electrode dressing layer (i.e., the edge surface layer) to be smaller than the active specific surface area of ​​the second positive electrode active material of the second positive electrode dressing layer (edge ​​bottom layer), it is beneficial to the slow deintercalation of lithium ions in the edge surface layer, and further helps to reduce the problem of lithium plating at the edge of the corresponding negative electrode, especially to reduce the problem of lithium plating at the edge that is prone to occur during fast charging.

[0075] According to some specific embodiments of the present application, the ratio of the active specific surface area of ​​the second positive electrode active material to the active specific surface area of ​​the first positive electrode active material is 1.05 to 4.5, and as an example, it can be 1.05 / 1.1 / 1.2 / 1.4 / 1.6 / 1.8 / 2 / 2.2 / 2.5 / 3 / 3.5 / 4 / 4.5, etc.; and / or, the ratio of the active specific surface area of ​​the third positive electrode active material to the active specific surface area of ​​the first positive electrode active material is 1.05 to 5, and as an example, it can be 1.05 / 1.1 / 1.2 / 1.4 / 1.6 / 1.8 / 2 / 2.2 / 2.5 / 3 / 3.5 / 4 / 4.5 / 5, etc. Thus, it is further beneficial to reduce the problem of lithium precipitation at the edge of the corresponding negative electrode, and further beneficial to the rapid deintercalation of lithium ions at the edge surface.

[0076] According to some further specific embodiments of the present application, the gram capacity of the first positive electrode active material is less than the gram capacity of the second positive electrode active material and less than the gram capacity of the third positive electrode active material. As a result, the delithiation capacity of the first region positive electrode active material layer in the edge region of the positive electrode sheet can be made weaker than the delithiation capacity of the second region positive electrode active material layer in the center region, thereby effectively reducing the accumulation of lithium ions at the edge of the electrode sheet and reducing the problem of lithium deposition at the edge of the corresponding negative electrode sheet. At the same time, the delithiation capacity of the edge surface layer can be made weaker than the delithiation capacity of the edge bottom layer, which is further beneficial to reducing the problem of lithium deposition at the edge of the corresponding negative electrode sheet.

[0077] According to some other specific embodiments of the present application, the ratio of the gram capacity of the second positive electrode active material to the gram capacity of the first positive electrode active material is 1.005-1.03, and as an example, it can be 1.005 / 1.01 / 1.015 / 1.02 / 1.025 / 1.03, etc.; and / or, the ratio of the gram capacity of the third positive electrode active material to the gram capacity of the first positive electrode active material is 1.01-1.06, and as an example, it can be 1.01 / 1.015 / 1.02 / 1.025 / 1.03 / 1.035 / 1.04 / 1.045 / 1.05 / 1.06, etc. Thus, it is further beneficial to reduce the accumulation of lithium ions at the edge of the pole piece, thereby further helping to reduce the problem of lithium deposition at the edge of the corresponding negative electrode piece.

[0078] In the embodiments of the present application, the specific types of the first positive electrode active material, the second positive electrode active material and the third positive electrode active material are not particularly limited, and those skilled in the art can select them according to actual needs. As some preferred embodiments, the first positive electrode active material, the second positive electrode active material and the third positive electrode active material respectively include LiCoO2, LiFePO4, LiNi x Co y Mn 1-x-y At least one of O2, LiMnO4, and lithium-rich manganese.

[0079] In the embodiments of the present application, different types of positive electrode active materials can be used to adjust the active specific surface area or gram capacity of the first positive electrode active material, the second positive electrode active material and the third positive electrode active material. The same type of positive electrode active material can also be used to adjust the active specific surface area or gram capacity of the first positive electrode active material, the second positive electrode active material and the third positive electrode active material by mixing the same type of positive electrode active materials with different particle sizes, voids or morphologies. For example, the same type of positive electrode active material LiFePO4, with different particle sizes, voids or morphologies, will result in different active specific surface areas or gram capacities.

[0080] According to some other specific embodiments of the present application, the first positive electrode dressing layer also includes a first positive electrode conductive agent, the second positive electrode dressing layer also includes a second positive electrode conductive agent, and the second region positive electrode active material layer also includes a third positive electrode conductive agent, and the resistivity of the first positive electrode conductive agent> the resistivity of the second positive electrode conductive agent≥ the resistivity of the third positive electrode conductive agent. Thus, the lithium ion diffusion rate of the first region positive electrode active material layer in the edge region of the positive electrode sheet can be further made weaker than the lithium ion diffusion rate of the second region positive electrode active material layer in the center region, thereby effectively reducing the accumulation of lithium ions at the edge of the electrode sheet and reducing the problem of lithium precipitation at the edge of the corresponding negative electrode sheet. At the same time, the lithium ion diffusion rate of the edge surface layer can be made weaker than the lithium ion diffusion rate of the edge bottom layer, which is further beneficial to reduce the problem of lithium precipitation at the edge of the corresponding negative electrode sheet. It can be understood that the conductive agent can increase the specific surface area of ​​the electrode and increase the contact area between the lithium ions and the electrode material, thereby reducing the diffusion path of the lithium ions and increasing the diffusion rate of the lithium ions. It is understandable that the conductive agent can increase the specific surface area of ​​the electrode and increase the contact area between lithium ions and the electrode material, thereby reducing the diffusion path of lithium ions and increasing the diffusion rate of lithium ions.

[0081] According to some specific embodiments of the present application, the ratio of the resistivity of the first positive electrode conductive agent to the resistivity of the second positive electrode conductive agent is 1.2 to 4, and as an example, it can be 1.2 / 1.5 / 2 / 2.5 / 3 / 3.5 / 4, etc.; and / or, the ratio of the resistivity of the first positive electrode conductive agent to the resistivity of the third positive electrode conductive agent is 2 to 6, and as an example, it can be 2 / 3 / 4 / 5 / 6, etc. Thus, it is further beneficial to reduce the accumulation of lithium ions at the edge of the electrode sheet, thereby further helping to reduce the problem of lithium deposition at the edge of the corresponding negative electrode sheet.

[0082] According to some other specific embodiments of the present application, the content of the first positive electrode conductor in the first positive electrode dressing layer is less than the content of the second positive electrode conductor in the second positive electrode dressing layer ≤ the content of the third positive electrode conductor in the second region positive electrode active material layer. As a result, the lithium ion diffusion rate of the first region positive electrode active material layer in the edge region of the positive electrode sheet can be further made weaker than the lithium ion diffusion rate of the second region positive electrode active material layer in the center region, thereby effectively reducing the accumulation of lithium ions at the edge of the electrode sheet and reducing the problem of lithium deposition at the edge of the corresponding negative electrode sheet. At the same time, the lithium ion diffusion rate of the edge surface layer can be further made weaker than the lithium ion diffusion rate of the edge bottom layer, which is further beneficial to reduce the problem of lithium deposition at the edge of the corresponding negative electrode sheet.

[0083] In the embodiments of the present application, the specific types of the first positive electrode conductive agent, the second positive electrode conductive agent and the third positive electrode conductive agent are not particularly limited, and those skilled in the art can select them according to actual needs. As some preferred embodiments, the first positive electrode conductive agent, the second positive electrode conductive agent and the third positive electrode conductive agent respectively include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0084] In the embodiment of the present application, different types of positive electrode conductive agents can be used to adjust the resistivity of the first positive electrode conductive agent, the second positive electrode conductive agent and the third positive electrode conductive agent, or the same type of positive electrode conductive agent can be used to adjust the resistivity of the first positive electrode conductive agent, the second positive electrode conductive agent and the third positive electrode conductive agent by mixing the same type of conductive agents with different particle sizes, voids or morphologies. For example, the same type of positive electrode conductive agent carbon nanotubes, with different particle sizes, voids or morphologies, will result in different resistivities.

[0085] According to some other specific embodiments of the present application, the ratio of the content of the second positive electrode conductive agent in the second positive electrode dressing layer to the content of the first positive electrode conductive agent in the first positive electrode dressing layer is 1.01-2, and as an example, it can be 1.01 / 1.02 / 1.05 / 1.1 / 1.2 / 1.3 / 1.4 / 1.5 / 1.6 / 1.7 / 1.8 / 1.9 / 2, etc.; and / or, the ratio of the content of the third positive electrode conductive agent in the second region positive electrode active material layer to the content of the first positive electrode conductive agent in the first positive electrode dressing layer is 1.03-2, and as an example, it can be 1.03 / 1.05 / 1.1 / 1.2 / 1.3 / 1.4 / 1.5 / 1.6 / 1.7 / 1.8 / 1.9 / 2, etc. Thus, it is further beneficial to reduce the accumulation of lithium ions at the edge of the pole piece, thereby further helping to reduce the problem of lithium deposition at the edge of the corresponding negative electrode piece.

[0086] According to some other specific embodiments of the present application, the first positive electrode dressing layer also includes a first positive electrode binder, the second positive electrode dressing layer also includes a second positive electrode binder, and the second-region positive electrode active material layer also includes a third positive electrode binder, and the content of the first positive electrode binder in the first positive electrode dressing layer>the content of the second positive electrode binder in the second positive electrode dressing layer≥the content of the third positive electrode binder in the second-region positive electrode active material layer. Thus, the lithium ion diffusion rate of the first-region positive electrode active material layer in the edge region of the positive electrode sheet can be further made weaker than the lithium ion diffusion rate of the second-region positive electrode active material layer in the center region, thereby effectively reducing the accumulation of lithium ions at the edge of the electrode sheet and reducing the problem of lithium deposition at the edge of the corresponding negative electrode sheet. At the same time, the lithium ion diffusion rate of the edge surface layer can be further made weaker than the lithium ion diffusion rate of the edge bottom layer, which is further beneficial to reduce the problem of lithium deposition at the edge of the corresponding negative electrode sheet.

[0087] According to some other specific embodiments of the present application, the ratio of the content of the first positive electrode binder in the first positive electrode dressing layer to the content of the second positive electrode binder in the second positive electrode dressing layer is 1.005-1.5, and as an example, it can be 1.005 / 1.01 / 1.03 / 1.05 / 1.1 / 1.2 / 1.3 / 1.5, etc.; and / or, the ratio of the content of the first positive electrode binder in the first positive electrode dressing layer to the content of the third positive electrode binder in the second region positive electrode active material layer is 1.005-2, and as an example, it can be 1.005 / 1.01 / 1.03 / 1.05 / 1.1 / 1.2 / 1.3 / 1.4 / 1.5 / 1.6 / 1.7 / 1.8 / 1.9 / 2, etc. Thus, it is further beneficial to reduce the accumulation of lithium ions at the edge of the pole piece, thereby further helping to reduce the problem of lithium deposition at the edge of the corresponding negative electrode piece.

[0088] In the embodiments of the present application, the specific types of the above-mentioned first positive electrode binder, the second positive electrode binder and the third positive electrode binder are not particularly limited, and those skilled in the art can select them according to actual needs. As some preferred embodiments, the above-mentioned first positive electrode binder, the second positive electrode binder and the third positive electrode binder respectively include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.

[0089] According to some other specific embodiments of the present application, the capacity per unit area of ​​the positive electrode active material layer in the second region ≥ the capacity per unit area of ​​the first positive electrode dressing layer + the capacity per unit area of ​​the second positive electrode dressing layer, thereby further ensuring that the deintercalation and deintercalation capability of the negative electrode active material layer in the first region in the edge region for lithium ions is weaker than that of the negative electrode active material layer in the second region in the center region for lithium ions, thereby effectively reducing the accumulation of lithium ions at the edge of the electrode sheet and reducing the problem of lithium plating at the edge of the corresponding negative electrode sheet.

[0090] According to some other specific embodiments of the present application, the surface density of the positive electrode active material layer in the second region = the surface density of the first positive electrode dressing layer + the surface density of the second positive electrode dressing layer, thereby further ensuring that the lithium ion diffusion capacity of the negative electrode active material layer in the first region in the edge region is weaker than the lithium ion diffusion capacity of the negative electrode active material layer in the second region in the center region, further reducing the problem of lithium plating at the edge of the corresponding negative electrode sheet.

[0091] According to some other specific embodiments of the present application, the thickness ratio of the first positive electrode dressing layer to the thickness ratio of the second positive electrode dressing layer is 5:(1-8), and as an example, it can be 5:1, 5:2, 5:3, 5:4, 5:5, 5:6, 5:7, 5:8, etc.; and / or, the width W1' of the positive electrode active material layer in the first region on one side is smaller than the width W2' of the positive electrode active material layer in the second region. Thus, the problem of lithium deposition at the edge of the corresponding negative electrode sheet can be further reduced.

[0092] In the third aspect of the present application, the present application provides a battery. According to the embodiments of the present application, referring to the attached Figure 3 The battery has the negative electrode sheet 100 described in the above embodiment and / or the positive electrode sheet 200 described in the above embodiment. Thus, the problem of lithium deposition at the edge of the negative electrode sheet is effectively reduced, which is conducive to ensuring the cycle performance and safety performance of the battery.

[0093] According to some specific embodiments of the present application, the width of the negative electrode sheet on one side beyond the positive electrode sheet on the same side is W0, the width W1 of the negative electrode active material layer in the first region on one side satisfies W0+2≤W1≤W0+6mm; the width W1' of the positive electrode active material layer in the first region on one side satisfies W0+2≤W1'≤W0+6mm. This is further conducive to reducing the accumulation of lithium ions at the edge of the electrode sheet, thereby further helping to reduce the problem of lithium deposition at the edge of the negative electrode sheet.

[0094] In the embodiments of the present application, the battery can be either a lithium-ion battery or a sodium-ion battery. The following description will take a lithium-ion battery as an example.

[0095] Specifically, refer to the attached Figure 3The lithium-ion battery includes the positive electrode sheet 200, the negative electrode sheet 100 and the separator 300 of the above embodiment, and the separator 300 is arranged between the positive electrode sheet 200 and the negative electrode sheet 100. During the battery charging and discharging process, the active ions lithium ions are embedded and extracted back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, and at the same time to allow ions to pass through.

[0096] The specific material of the above-mentioned diaphragm is not particularly limited. As some specific embodiments, the above-mentioned diaphragm includes at least one of a PP diaphragm, a PE diaphragm, a single-sided ceramic diaphragm, a double-sided ceramic diaphragm, a non-woven fabric diaphragm, and a glass fiber diaphragm.

[0097] The battery of the present application may include a battery cell form, a battery module form and a battery pack form. In some embodiments, the battery cells can be assembled into a battery module, and the number of battery cells contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module. In some embodiments, the battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0098] In the fourth aspect of the present application, the present application proposes an electric device. According to an embodiment of the present application, the electric device has the battery described in the above embodiment. Therefore, the electric device has all the advantages of the battery, which will not be repeated here.

[0099] Specifically, the electrical equipment may be, but is not limited to, mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. Electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft may include airplanes, rockets, space shuttles, and spacecraft, etc.

[0100] It should be noted that the features and advantages described above for the battery are also applicable to the electrical device and will not be described in detail here.

[0101] The embodiments of the present application are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. In addition, unless otherwise explicitly stated, all reagents used in the following embodiments are commercially available or can be synthesized according to this article or known methods, and the reaction conditions not listed are also easily available to those skilled in the art.

[0102] Example 1

[0103] This embodiment provides a lithium ion battery, and the preparation method thereof includes:

[0104] 1) Preparation of negative electrode

[0105] A negative electrode active material layer is formed by coating the surface of the negative electrode current collector, wherein the negative electrode active material layer includes a first region negative electrode active material layer and a second region negative electrode active material layer, wherein the first region negative electrode active material layer is arranged on both side edges of the second region negative electrode active material layer along the width direction, and the first region negative electrode active material layer includes a first negative electrode dressing layer (upper layer) and a second negative electrode dressing layer (lower layer) stacked along the thickness direction. The first negative electrode dressing layer includes 95.2 parts by weight of the first negative electrode active material artificial graphite, 1.2 parts by weight of the first negative electrode conductive agent carbon black and 3.6 parts by weight of the first negative electrode binder CMC+SBR, the second negative electrode dressing layer includes 95.2 parts by weight of the second negative electrode active material artificial graphite, 1.0 parts by weight of the second negative electrode conductive agent carbon black and 3.8 parts by weight of the second negative electrode binder CMC+SBR, and the second region negative electrode active material layer includes 95.3 parts by weight of the third negative electrode active material artificial graphite, 0.8 parts by weight of the third negative electrode conductive agent carbon black and 3.9 parts by weight of the third negative electrode binder CMC+SBR.

[0106] Among them, the active specific surface area of ​​the first negative electrode active material is 1.92m 2 / g, and the active specific surface area of ​​the second negative electrode active material is 1.53m 2 / g, the active specific surface area of ​​the third negative electrode active material is 0.95m 2 / g.

[0107] The gram capacity of the first negative electrode active material is 354 mAh / g; the gram capacity of the second negative electrode active material is 352 mAh / g, and the gram capacity of the third negative electrode active material is 350 mAh / g.

[0108] The resistivity of the first negative electrode conductive agent powder is 8Ω.cm, the resistivity of the second negative electrode conductive agent powder is 22Ω.cm, and the resistivity of the third negative electrode conductive agent powder is 50Ω.cm.

[0109] The first area dressing layer has a first width W1 of 4 mm, and the second area dressing layer has a second width W2 of 80 mm.

[0110] The single-side overhang dimension W0 of the positive and negative electrode sheets of the battery in the width direction is 2 mm, and the relationship between W0 and W1 satisfies W0+2≤W1≤W0+6 mm.

[0111] The height H1 of the first negative electrode dressing layer (upper layer) is 52 μm, and the height H2 of the second negative electrode dressing layer (lower layer) is 52 μm. The surface density of the first negative electrode dressing layer (upper layer) is 166 g / m 2 The surface density of the second negative electrode dressing layer (lower layer) is 83g / m 2 The surface density of the negative electrode active material layer in the second region is 83 g / m 2 .

[0112] 2) Preparation of positive electrode

[0113] The positive electrode active material layer is coated on the surface of the positive electrode current collector, and the positive electrode active material layer includes 96.4 parts by weight of positive electrode active material LiFePO4, 1.5 parts by weight of positive electrode conductive agent carbon nanotubes and 2.1 parts by weight of positive electrode binder PVDF. The active specific surface area of ​​the positive electrode active material is 8m 2 / g, the gram capacity of the positive electrode active material is 144mAh / g, and the resistivity of the positive electrode conductive agent powder is 8Ω.cm.

[0114] 3) Preparation of electrolyte

[0115] In an argon atmosphere glove box with a moisture content of ≤1ppm, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1, and then the dry electrolyte lithium salt LiPF6 was dissolved in the solvent. The mass proportion of LiPF6 in the electrolyte was 16%.

[0116] 4) Isolation film

[0117] A polyethylene film with a thickness of 16 microns was selected as the diaphragm.

[0118] 5) Battery assembly

[0119] The prepared battery pole pieces, separators, and negative electrode pieces are stacked in order so that the separator is in the middle of the positive and negative electrodes to separate the positive and negative electrode pieces, and are wound to form bare battery cells. After welding the pole ears, the bare battery cells are assembled into outer packaging, and after injecting the prepared electrolyte, the battery cells are packaged, left to stand, formed, shaped, and capacity tested, and finally a lithium-ion battery is prepared.

[0120] Example 2

[0121] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

[0122] 1) Preparation of negative electrode

[0123] The active specific surface area of ​​the first negative electrode active material is 1.14 m 2 / g, and the active specific surface area of ​​the second negative electrode active material is 1.036m 2 / g, the active specific surface area of ​​the third negative electrode active material is 0.95m 2 / g.

[0124] Example 3

[0125] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

[0126] 1) Preparation of negative electrode

[0127] The active specific surface area of ​​the first negative electrode active material is 1.615 m 2 / g, and the active specific surface area of ​​the second negative electrode active material is 1.077m 2 / g, the active specific surface area of ​​the third negative electrode active material is 0.95m 2 / g.

[0128] Example 4

[0129] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

[0130] 1) Preparation of negative electrode

[0131] The active specific surface area of ​​the first negative electrode active material is 2.09 m 2 / g, and the active specific surface area of ​​the second negative electrode active material is 1.045m 2 / g, the active specific surface area of ​​the third negative electrode active material is 0.95m 2 / g.

[0132] Example 5

[0133] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

[0134] 1) Preparation of negative electrode

[0135] The gram capacity of the first negative electrode active material is 357 mAh / g; the gram capacity of the second negative electrode active material is 353.5 mAh / g, and the gram capacity of the third negative electrode active material is 350 mAh / g.

[0136] Example 6

[0137] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

[0138] 1) Preparation of negative electrode

[0139] The gram capacity of the first negative electrode active material is 360.5 mAh / g; the gram capacity of the second negative electrode active material is 353.4 mAh / g, and the gram capacity of the third negative electrode active material is 350 mAh / g.

[0140] Example 7

[0141] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

[0142] 1) Preparation of negative electrode

[0143] The gram capacity of the first negative electrode active material is 364 mAh / g; the gram capacity of the second negative electrode active material is 353.4 mAh / g, and the gram capacity of the third negative electrode active material is 350 mAh / g.

[0144] Example 8

[0145] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

[0146] 1) Preparation of negative electrode

[0147] The resistivity of the first negative electrode conductive agent powder is 10Ω.cm, the resistivity of the second negative electrode conductive agent powder is 20Ω.cm, and the resistivity of the third negative electrode conductive agent powder is 50Ω.cm.

[0148] Example 9

[0149] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

[0150] 1) Preparation of negative electrode

[0151] The resistivity of the first negative electrode conductive agent powder is 7Ω.cm, the resistivity of the second negative electrode conductive agent powder is 21Ω.cm, and the resistivity of the third negative electrode conductive agent powder is 50Ω.cm.

[0152] Example 10

[0153] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

[0154] 1) Preparation of negative electrode

[0155] The first negative electrode dressing layer includes 95.2 parts by weight of the first negative electrode active material artificial graphite, 1.36 parts by weight of the first negative electrode conductive agent carbon black and 3.44 parts by weight of the first negative electrode binder CMC+SBR, the second negative electrode dressing layer includes 95.3 parts by weight of the second negative electrode active material artificial graphite, 0.9 parts by weight of the second negative electrode conductive agent carbon black and 3.8 parts by weight of the second negative electrode binder CMC+SBR, and the second region negative electrode active material layer includes 95.3 parts by weight of the third negative electrode active material artificial graphite, 0.8 parts by weight of the third negative electrode conductive agent carbon black and 3.9 parts by weight of the third negative electrode binder CMC+SBR.

[0156] Embodiment 11

[0157] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 1, except that:

[0158] 1) Preparation of negative electrode

[0159] The first negative electrode dressing layer includes 95.2 parts by weight of the first negative electrode active material artificial graphite, 1.52 parts by weight of the first negative electrode conductive agent carbon black and 3.28 parts by weight of the first negative electrode binder CMC+SBR, the second negative electrode dressing layer includes 95.3 parts by weight of the second negative electrode active material artificial graphite, 0.89 parts by weight of the second negative electrode conductive agent carbon black and 3.81 parts by weight of the second negative electrode binder CMC+SBR, and the second region negative electrode active material layer includes 95.3 parts by weight of the third negative electrode active material artificial graphite, 0.8 parts by weight of the third negative electrode conductive agent carbon black and 3.9 parts by weight of the third negative electrode binder CMC+SBR.

[0160] Example 12

[0161] This embodiment provides a lithium ion battery, and the preparation method thereof includes:

[0162] 1) Preparation of positive electrode

[0163] A positive electrode active material layer is formed by coating the surface of the positive electrode current collector, the positive electrode active material layer includes a first region positive electrode active material layer and a second region positive electrode active material layer, the first region positive electrode active material layer is arranged at both side edges of the second region positive electrode active material layer in the width direction, and the first region positive electrode active material layer includes a first positive electrode dressing layer and a second positive electrode dressing layer stacked in the thickness direction. The first positive electrode dressing layer includes 96.5 parts by weight of the first positive electrode active material LiFePO4, 1.0 parts by weight of the first positive electrode conductive agent carbon nanotubes, and 2.5 parts by weight of the first positive electrode binder PVDF, the second positive electrode dressing layer includes 96.4 parts by weight of the second positive electrode active material LiFePO4, 1.3 parts by weight of the second positive electrode conductive agent carbon nanotubes, and 2.3 parts by weight of the second positive electrode binder PVDF, and the second region positive electrode active material layer includes 96.4 parts by weight of the third positive electrode active material LiFePO4, 1.5 parts by weight of the third positive electrode conductive agent carbon nanotubes, and 2.1 parts by weight of the third positive electrode binder PVDF.

[0164] Among them, the active specific surface area of ​​the first positive electrode active material is 5.5m 2 / g, and the active specific surface area of ​​the second positive electrode active material is 6.5m 2 / g, the active specific surface area of ​​the third positive electrode active material is 8m 2 / g.

[0165] The gram capacity of the first positive electrode active material is 140 mAh / g; the gram capacity of the second positive electrode active material is 142 mAh / g, and the gram capacity of the third positive electrode active material is 144 mAh / g.

[0166] The resistivity of the first positive electrode conductive agent powder is 22Ω.cm, the resistivity of the second positive electrode conductive agent powder is 16Ω.cm, and the resistivity of the third positive electrode conductive agent powder is 8Ω.cm.

[0167] The first area dressing layer has a first width W1 of 5 mm, and the second area dressing layer has a second width W2 of 78 mm.

[0168] The overhang size W0 on one side of the positive and negative electrode sheets in the width direction of the battery is 2mm, and the relationship between W0 and W1 satisfies W0+2≤W1≤W0+6mm;

[0169] The height H1 of the first positive electrode dressing layer (upper layer) is 66 μm, and the height H2 of the second positive electrode dressing layer (lower layer) is 66 μm. The surface density of the first positive electrode dressing layer (upper layer) is 346 g / m 2 The surface density of the second positive electrode dressing layer (lower layer) is 173g / m 2 The surface density of the positive electrode active material layer in the second region is 173 g / m 2 .

[0170] 2) Preparation of negative electrode

[0171] The negative electrode active material layer is coated on the surface of the negative electrode current collector. The negative electrode active material layer includes 95.3 parts by weight of artificial graphite as a negative electrode active material, 0.8 parts by weight of carbon black as a negative electrode conductive agent, and 3.9 parts by weight of CMC+SBR as a negative electrode binder. The active specific surface area of ​​the negative electrode active material is 0.95m 2 / g, the gram capacity of the negative electrode active material is 350mAh / g, and the resistivity of the negative electrode conductive agent powder is 50Ω.cm.

[0172] 3) Preparation of electrolyte

[0173] In an argon atmosphere glove box with a moisture content of ≤1ppm, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1, and then the dry electrolyte lithium salt LiPF6 was dissolved in the solvent. The mass proportion of LiPF6 in the electrolyte was 16%.

[0174] 4) Isolation film

[0175] A polyethylene film with a thickness of 16 microns was selected as the diaphragm.

[0176] 5) Battery assembly

[0177] The prepared battery pole pieces, separators, and negative electrode pieces are stacked in order so that the separator is in the middle of the positive and negative electrodes to separate the positive and negative electrode pieces, and are wound to form bare battery cells. After welding the pole ears, the bare battery cells are assembled into outer packaging, and after injecting the prepared electrolyte, the battery cells are packaged, left to stand, formed, shaped, and capacity tested, and finally a lithium-ion battery is prepared.

[0178] Embodiment 13

[0179] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 12, except that:

[0180] 1) Preparation of positive electrode

[0181] The active specific surface area of ​​the first positive electrode active material is 4 m 2 / g, the active specific surface area of ​​the second positive electrode active material is 6m 2 / g, the active specific surface area of ​​the third positive electrode active material is 8m 2 / g.

[0182] Embodiment 14

[0183] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 12, except that:

[0184] 1) Preparation of positive electrode

[0185] The active specific surface area of ​​the first positive electrode active material is 3.6 m 2 / g, and the active specific surface area of ​​the second positive electrode active material is 7.3m 2 / g, the active specific surface area of ​​the third positive electrode active material is 8m 2 / g.

[0186] Embodiment 15

[0187] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 12, except that:

[0188] 1) Preparation of positive electrode

[0189] The active specific surface area of ​​the first positive electrode active material is 2.3 m 2 / g, and the active specific surface area of ​​the second positive electrode active material is 6.9 m 2 / g, the active specific surface area of ​​the third positive electrode active material is 8m 2 / g.

[0190] Example 16

[0191] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 12, except that:

[0192] 1) Preparation of positive electrode

[0193] The gram capacity of the first positive electrode active material is 139 mAh / g; the gram capacity of the second positive electrode active material is 142 mAh / g, and the gram capacity of the third positive electrode active material is 144 mAh / g.

[0194] Embodiment 17

[0195] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 12, except that:

[0196] 1) Preparation of positive electrode

[0197] The gram capacity of the first positive electrode active material is 136 mAh / g; the gram capacity of the second positive electrode active material is 138 mAh / g, and the gram capacity of the third positive electrode active material is 144 mAh / g.

[0198] Embodiment 18

[0199] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 12, except that:

[0200] 1) Preparation of positive electrode

[0201] The resistivity of the first positive electrode conductive agent powder is 24Ω.cm, the resistivity of the second positive electrode conductive agent powder is 12Ω.cm, and the resistivity of the third positive electrode conductive agent powder is 8Ω.cm.

[0202] Embodiment 19

[0203] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 12, except that:

[0204] 1) Preparation of positive electrode

[0205] The resistivity of the first positive electrode conductive agent powder is 32Ω.cm, the resistivity of the second positive electrode conductive agent powder is 11Ω.cm, and the resistivity of the third positive electrode conductive agent powder is 8Ω.cm.

[0206] Embodiment 20

[0207] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 12, except that:

[0208] 1) Preparation of positive electrode

[0209] The first positive electrode dressing layer includes 96.5 parts by weight of the first positive electrode active material, 1.15 parts by weight of the first positive electrode conductor and 2.35 parts by weight of the first positive electrode binder, the second positive electrode dressing layer includes 96.4 parts by weight of the second positive electrode active material, 1.27 parts by weight of the second positive electrode conductor and 2.33 parts by weight of the second positive electrode binder, and the second regional positive electrode active material layer includes 96.4 parts by weight of the third positive electrode active material, 1.5 parts by weight of the third positive electrode conductor and 2.1 parts by weight of the third positive electrode binder.

[0210] Embodiment 21

[0211] This embodiment provides a lithium ion battery. The preparation method of this embodiment is basically the same as that of embodiment 12, except that:

[0212] 1) Preparation of positive electrode

[0213] The first positive electrode dressing layer includes 96.5 parts by weight of the first positive electrode active material, 0.83 parts by weight of the first positive electrode conductor and 2.67 parts by weight of the first positive electrode binder, the second positive electrode dressing layer includes 96.4 parts by weight of the second positive electrode active material, 1.33 parts by weight of the second positive electrode conductor and 2.27 parts by weight of the second positive electrode binder, and the second regional positive electrode active material layer includes 96.4 parts by weight of the third positive electrode active material, 1.5 parts by weight of the third positive electrode conductor and 2.1 parts by weight of the third positive electrode binder.

[0214] Comparative Example 1

[0215] This comparative example provides a lithium ion battery. The preparation method of this comparative example is basically the same as that of Example 1, except that:

[0216] 1) Preparation of negative electrode

[0217] The negative electrode active material layer is coated on the surface of the negative electrode current collector. The negative electrode active material layer includes 95.3 parts by weight of artificial graphite as a negative electrode active material, 0.8 parts by weight of carbon black as a negative electrode conductive agent, and 3.9 parts by weight of CMC+SBR as a negative electrode binder. The active specific surface area of ​​the negative electrode active material is 0.95m 2 / g, the gram capacity of the negative electrode active material is 350mAh / g, and the resistivity of the negative electrode conductive agent powder is 50Ω.cm.

[0218] The batteries prepared in Examples 1 to 21 and Comparative Example 1 were charged to the upper limit voltage at 2C, left for 60 min, discharged to the cut-off voltage at 1C, left for 60 min, and cycled for 500 cycles. The batteries were disassembled every 100 cycles to see whether lithium was deposited at the interface edge of the negative electrode sheet. The results are shown in Table 1.

[0219] Table 1

[0220]

[0221]

[0222] As can be seen from Table 1, compared with Comparative Example 1, the negative electrode sheets of Examples 1 to 11 did not have edge lithium deposition, and the capacity retention rate decreased less with the increase in the number of cycles. However, the negative electrode sheet of Comparative Example 1 had edge lithium deposition after 300 cycles, and the capacity retention rate decreased more with the increase in the number of cycles.

[0223] As can be seen from Table 1, compared with Comparative Example 1, the negative electrode sheets of Examples 12 to 21 did not have edge lithium deposition, and the capacity retention rate decreased less with the increase in the number of cycles. However, the negative electrode sheet of Comparative Example 1 had edge lithium deposition at 300 cycles, and the capacity retention rate decreased more with the increase in the number of cycles.

[0224] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0225] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A negative electrode sheet, characterized in that: include: Anode current collector; A negative electrode active material layer, wherein the negative electrode active material layer is disposed on at least a portion of the surface of the negative electrode collector, the negative electrode active material layer comprises a first region negative electrode active material layer and a second region negative electrode active material layer, the first region negative electrode active material layer is disposed on at least one side edge of the second region negative electrode active material layer in the width direction, the first region negative electrode active material layer comprises a first negative electrode dressing layer and a second negative electrode dressing layer stacked in the thickness direction, and the second negative electrode dressing layer is disposed on the surface of the negative electrode collector, and the first negative electrode dressing layer is disposed on the surface of the first negative electrode dressing layer away from the negative electrode collector; The first negative electrode dressing layer includes a first negative electrode active material, the second negative electrode dressing layer includes a second negative electrode active material, the second regional negative electrode active material layer includes a third negative electrode active material, and the active specific surface area of ​​the first negative electrode active material is greater than the active specific surface area of ​​the second negative electrode active material and greater than the active specific surface area of ​​the third negative electrode active material.

2. The negative electrode sheet according to claim 1, characterized in that: The ratio of the active specific surface area of ​​the first negative electrode active material to the active specific surface area of ​​the second negative electrode active material is 1.05 to 2.5; And / or, the ratio of the active specific surface area of ​​the first negative electrode active material to the active specific surface area of ​​the third negative electrode active material is 1.05-3.

3. The negative electrode sheet according to claim 1, characterized in that: The gram capacity of the first negative electrode active material>the gram capacity of the second negative electrode active material≥the gram capacity of the third negative electrode active material.

4. The negative electrode sheet according to claim 3, characterized in that: The ratio of the gram capacity of the first negative electrode active material to the gram capacity of the second negative electrode active material is 1.005 to 1.03; And / or, the ratio of the gram capacity of the first negative electrode active material to the gram capacity of the third negative electrode active material is 1.01 to 1.

05.

5. The negative electrode sheet according to claim 1, characterized in that: The first negative electrode dressing layer also includes a first negative electrode conductive agent, the second negative electrode dressing layer also includes a second negative electrode conductive agent, and the second region negative electrode active material layer also includes a third negative electrode conductive agent, and the resistivity of the first negative electrode conductive agent is less than the resistivity of the second negative electrode conductive agent and less than the resistivity of the third negative electrode conductive agent.

6. The negative electrode sheet according to claim 5, characterized in that: The ratio of the resistivity of the second negative electrode conductive agent to the resistivity of the first negative electrode conductive agent is 1.5 to 4; And / or, a ratio of the resistivity of the third negative electrode conductive agent to the resistivity of the first negative electrode conductive agent is 4-9.

7. The negative electrode sheet according to claim 5, characterized in that: The content of the first negative electrode conductive agent in the first negative electrode dressing layer>the content of the second negative electrode conductive agent in the second negative electrode dressing layer≥the content of the third negative electrode conductive agent in the second region negative electrode active material layer.

8. The negative electrode sheet according to claim 7, characterized in that: The ratio of the content of the first negative electrode conductive agent in the first negative electrode dressing layer to the content of the second negative electrode conductive agent in the second negative electrode dressing layer is 1.01 to 2; And / or, the ratio of the content of the first negative electrode conductive agent in the first negative electrode dressing layer to the content of the third negative electrode conductive agent in the second region negative electrode active material layer is 1.03-2.

9. The negative electrode sheet according to claim 1, characterized in that: The first negative electrode dressing layer also includes a first negative electrode binder, the second negative electrode dressing layer also includes a second negative electrode binder, and the second-region negative electrode active material layer also includes a third negative electrode binder, and the content of the first negative electrode binder in the first negative electrode dressing layer is less than the content of the second negative electrode binder in the second negative electrode dressing layer and less than or equal to the content of the third negative electrode binder in the second-region negative electrode active material layer.

10. The negative electrode sheet according to claim 9, characterized in that: The ratio of the content of the second negative electrode binder in the second negative electrode dressing layer to the content of the first negative electrode binder in the first negative electrode dressing layer is 1.005 to 1.5; And / or, a ratio of a content of the third negative electrode binder in the second region negative electrode active material layer to a content of the first negative electrode binder in the first negative electrode dressing layer is 1.005-2.

11. The negative electrode sheet according to any one of claims 1 to 10, characterized in that: The capacity per unit area of ​​the negative electrode active material layer in the second region is ≤ the capacity per unit area of ​​the first negative electrode dressing layer + the capacity per unit area of ​​the second negative electrode dressing layer.

12. The negative electrode sheet according to any one of claims 1 to 10, characterized in that: The surface density of the negative electrode active material layer in the second region=the surface density of the first negative electrode dressing layer+the surface density of the second negative electrode dressing layer.

13. The negative electrode sheet according to any one of claims 1 to 10, characterized in that: The ratio of the thickness of the first negative electrode dressing layer to the thickness of the second negative electrode dressing layer is 5:(1-8); And / or, the width W1 of the negative electrode active material layer in the first region on one side is smaller than the width W2 of the negative electrode active material layer in the second region.

14. A positive electrode sheet, characterized in that: include: Positive electrode current collector; A positive electrode active material layer, wherein the positive electrode active material layer is disposed on at least a portion of the surface of the positive electrode collector, the positive electrode active material layer comprises a first region positive electrode active material layer and a second region positive electrode active material layer, the first region positive electrode active material layer is disposed on at least one side edge of the second region positive electrode active material layer in a width direction, the first region positive electrode active material layer comprises a first positive electrode dressing layer and a second positive electrode dressing layer stacked in a thickness direction, and the second positive electrode dressing layer is disposed on the surface of the positive electrode collector, and the first positive electrode dressing layer is disposed on a surface of the first positive electrode dressing layer away from the positive electrode collector; The first positive electrode dressing layer includes a first positive electrode active material, the second positive electrode dressing layer includes a second positive electrode active material, the second region positive electrode active material layer includes a third positive electrode active material, and the active specific surface area of ​​the first positive electrode active material is less than the active specific surface area of ​​the second positive electrode active material and less than the active specific surface area of ​​the third positive electrode active material.

15. The positive electrode sheet according to claim 14, characterized in that: The ratio of the active specific surface area of ​​the second positive electrode active material to the active specific surface area of ​​the first positive electrode active material is 1.05 to 4.5; And / or, the ratio of the active specific surface area of ​​the third positive electrode active material to the active specific surface area of ​​the first positive electrode active material is 1.05-5.

16. The positive electrode sheet according to claim 14, characterized in that: The gram capacity of the first positive electrode active material is less than the gram capacity of the second positive electrode active material and less than the gram capacity of the third positive electrode active material.

17. The positive electrode sheet according to claim 16, characterized in that: The ratio of the gram capacity of the second positive electrode active material to the gram capacity of the first positive electrode active material is 1.005 to 1.03; And / or, the ratio of the gram capacity of the third positive electrode active material to the gram capacity of the first positive electrode active material is 1.01 to 1.

06.

18. The positive electrode sheet according to claim 14, characterized in that: The first positive electrode dressing layer also includes a first positive electrode conductive agent, the second positive electrode dressing layer also includes a second positive electrode conductive agent, and the second region positive electrode active material layer also includes a third positive electrode conductive agent. The resistivity of the first positive electrode conductive agent is greater than the resistivity of the second positive electrode conductive agent and greater than the resistivity of the third positive electrode conductive agent.

19. The positive electrode sheet according to claim 18, characterized in that: The ratio of the resistivity of the first positive electrode conductive agent to the resistivity of the second positive electrode conductive agent is 1.2 to 4; And / or, a ratio of the resistivity of the first positive electrode conductive agent to the resistivity of the third positive electrode conductive agent is 2-6.

20. The positive electrode sheet according to claim 18, characterized in that: The content of the first positive electrode conductive agent in the first positive electrode dressing layer is less than the content of the second positive electrode conductive agent in the second positive electrode dressing layer and less than the content of the third positive electrode conductive agent in the second-region positive electrode active material layer.

21. The positive electrode sheet according to claim 20, characterized in that: The ratio of the content of the second positive electrode conductive agent in the second positive electrode dressing layer to the content of the first positive electrode conductive agent in the first positive electrode dressing layer is 1.01 to 2; And / or, the ratio of the content of the third positive electrode conductive agent in the second region positive electrode active material layer to the content of the first positive electrode conductive agent in the first positive electrode dressing layer is 1.03-2.

22. The positive electrode sheet according to claim 14, characterized in that: The first positive electrode dressing layer also includes a first positive electrode binder, the second positive electrode dressing layer also includes a second positive electrode binder, and the second-region positive electrode active material layer also includes a third positive electrode binder. The content of the first positive electrode binder in the first positive electrode dressing layer is greater than the content of the second positive electrode binder in the second positive electrode dressing layer, and greater than or equal to the content of the third positive electrode binder in the second-region positive electrode active material layer.

23. The positive electrode sheet according to claim 22, characterized in that: The ratio of the content of the first positive electrode binder in the first positive electrode dressing layer to the content of the second positive electrode binder in the second positive electrode dressing layer is 1.005 to 1.5; And / or, the ratio of the content of the first positive electrode binder in the first positive electrode dressing layer to the content of the third positive electrode binder in the second region positive electrode active material layer is 1.005-2.

24. The positive electrode sheet according to any one of claims 14 to 23, characterized in that: The capacity per unit area of ​​the positive electrode active material layer in the second region is ≥ the capacity per unit area of ​​the first positive electrode dressing layer + the capacity per unit area of ​​the second positive electrode dressing layer.

25. The positive electrode sheet according to any one of claims 14 to 23, characterized in that: The surface density of the positive electrode active material layer in the second region=the surface density of the first positive electrode dressing layer+the surface density of the second positive electrode dressing layer.

26. The positive electrode sheet according to any one of claims 14 to 23, characterized in that: The ratio of the thickness of the first positive electrode dressing layer to the thickness of the second positive electrode dressing layer is 5:(1-8); And / or, the width W1 ′ of the positive electrode active material layer in the first region on one side is smaller than the width W2 ′ of the positive electrode active material layer in the second region.

27. A battery, characterized in that: A method of providing a negative electrode sheet according to any one of claims 1 to 13 and / or a positive electrode sheet according to any one of claims 14 to 26.

28. The battery according to claim 27, characterized in that The width of the negative electrode sheet on one side exceeding the positive electrode sheet on the same side is W0, and the width W1 of the negative electrode active material layer in the first region on one side satisfies W0+2≤W1≤W0+6mm; The width W1 ′ of the positive electrode active material layer in the first region on one side satisfies W0+2≤W1 ′≤W0+6 mm.

29. An electrical equipment, characterized in that: A battery according to claim 27 or 28.

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