Battery pole piece, electrode assembly, battery cell, battery and electric device

Abstract

This application relates to a battery electrode, electrode assembly, battery cell, battery, and electrical device. The battery electrode includes a current collector, at least one side of which includes a coated area and an uncoated area. The coated area is coated with an active material layer and an insulating layer. The insulating layer is located on the side of the active material layer near the uncoated area. The insulating layer includes a first portion and a second portion connected together. The second portion is located at the edge region of the insulating layer near the active material layer. The active material layer is configured to cover the second portion, such that the active material layer and the insulating layer partially overlap along the thickness direction of the electrode. This application provides a battery electrode, electrode assembly, battery cell, battery, and electrical device, wherein the active material layer and insulating layer coated on the battery electrode can form a clear boundary, improving product yield.

Description

Technical Field

[0001] This application relates to the field of energy storage device technology, and in particular to a battery electrode, electrode assembly, battery cell, battery and power device. Background Technology

[0002] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools. Battery cells can include nickel-cadmium battery cells, nickel-metal hydride battery cells, lithium-ion battery cells, and rechargeable alkaline zinc-manganese battery cells, among others.

[0003] During the use of individual battery cells, lithium plating frequently occurs. The deposited lithium can puncture the separator, causing a short circuit and posing a safety risk. Therefore, the problem of lithium plating in individual battery cells urgently needs to be addressed. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a battery electrode, electrode assembly, battery cell, battery, and electrical device. The active material layer and insulating layer coated on the battery electrode can form a clear boundary, reducing the risk of lithium plating and improving product yield.

[0005] A first aspect of this application provides a battery electrode, which includes a current collector. At least one side of the current collector includes a coated area and an uncoated area connected together. The coated area is coated with an active material layer and an insulating layer. The insulating layer is located on the side of the active material layer near the uncoated area. The insulating layer includes a first portion and a second portion connected together. The second portion is located at the edge region of the insulating layer on the side near the active material layer. The active material layer is configured to cover the second portion but not the first portion, so that the active material layer and the insulating layer partially overlap along the thickness direction of the electrode.

[0006] The second part is covered by the active material layer. The second part will not penetrate to the upper surface of the active material layer. This reduces the problem of blurred boundaries caused by the mixing of coating slurry in the edge area of ​​the insulating layer near the active material layer. This forms a clear boundary line and reduces the problem of lithium plating caused by misjudging the boundary of the active material layer, which may result in the size of the positive electrode active material layer and the negative electrode active material layer not meeting the requirements.

[0007] In some embodiments, the thickness of the insulating layer is not greater than the thickness of the active material layer.

[0008] The thickness difference between the active material layer and the insulating layer reduces the risk of the active material layer and the insulating layer slurry mixing and penetrating to the upper surface of the active material layer.

[0009] In some embodiments, the thickness of the second part is not greater than the thickness of the first part.

[0010] The insulation layer is thinner, which reduces the problem of the total coating thickness increasing significantly and forming bulge edges due to the overlap between the active material layer and the second part, and improves the overall thickness consistency of the battery electrode.

[0011] In some embodiments, along the thickness direction, the shortest distance between the surface of the second portion facing the current collector and the surface of the current collector is 0-90 μm.

[0012] In some embodiments, the surface of the second portion away from the current collector is an inclined surface, and the inclined surface gradually approaches the current collector along the direction in which the first portion extends toward the active material layer.

[0013] The second part, with its surface away from the current collector, is sloped, reducing the risk of increased total coating thickness and bulging due to the overlap between the active material layer and the second part. Furthermore, during coating drying, the active material layer shrinks and slides along the sloped surface, reducing the penetration and mixing of the coating slurry from the second part into the active material layer.

[0014] In some embodiments, along the electrode thickness direction, the distance between the surface of the second portion away from the current collector and the outer surface of the active material layer is not less than 20 μm.

[0015] The distance between the surface of the second part away from the current collector and the outer surface of the active material layer is set to ensure that the second part is sufficiently far away from the outer surface of the active material layer, thereby reducing the possibility of the coating slurry of the second part penetrating to the outer surface of the active material layer.

[0016] In some embodiments, the maximum thickness of the second portion is 3-90 μm.

[0017] By setting the thickness of the second part to be relatively small, the coating thickness variation in the overlapping area between the active material layer and the second part will also be relatively small, preventing the coating thickness in the overlapping area between the active material layer and the insulating layer from significantly increasing and forming a bulging edge.

[0018] In some embodiments, along the direction in which the active material layer and the insulating layer are arranged, the width of the second portion is not greater than the width of the first portion.

[0019] By setting the widths of the first and second parts, excessive overlap between the second part and the active material layer can be avoided.

[0020] A second aspect of this application provides an electrode assembly including the battery electrode as described above.

[0021] A third aspect of this application provides a battery cell including the electrode assembly described above.

[0022] A fourth aspect of this application provides a battery comprising a plurality of battery cells as described above.

[0023] A fifth aspect of this application provides an electrical device, characterized in that it includes a battery as described above, the battery being used to provide electrical energy.

[0024] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only specific embodiments of this application. Those skilled in the art can obtain other embodiments based on the following drawings without creative effort.

[0026] Figure 1 A schematic diagram of the structure of the electrical device provided in this application in a specific embodiment;

[0027] Figure 2 This is an exploded view of a battery according to some embodiments of this application;

[0028] Figure 3 This is an exploded view of a battery cell according to some embodiments of this application;

[0029] Figure 4 This is a cross-sectional schematic diagram of an electrode assembly according to a specific embodiment of this application;

[0030] Figure 5 for Figure 4 A partial schematic diagram of the EE-directed cross-sectional view of the electrode assembly in the figure;

[0031] Figure 6 These are partial unfolded comparison diagrams of the positive and negative electrode sheets of some embodiments of this application;

[0032] Figure 7 This is a cross-sectional view of a battery electrode in one embodiment;

[0033] Figure 8 for Figure 7 Enlarged view of Part I;

[0034] Figure 9 This is a cross-sectional view of the battery electrode in another embodiment;

[0035] Figure 10 This is a cross-sectional view of the battery electrode in yet another embodiment.

[0036] Figure label:

[0037] A-Vehicle;

[0038] B-battery;

[0039] C-controller;

[0040] D-cell battery cell;

[0041] F - Enclosure;

[0042] F1-upper box;

[0043] F2-lower box;

[0044] M-motor;

[0045] 100 - Electrode assembly;

[0046] 200 - Housing;

[0047] 300-End Cap Assembly;

[0048] 1-Battery electrode;

[0049] 1a - Positive electrode plate;

[0050] 1b - Negative electrode plate;

[0051] 11-Current collector;

[0052] 11a - Positive current collector;

[0053] 11b - Negative electrode current collector;

[0054] 111-Ear;

[0055] 111a - Positive electrode tab;

[0056] 111b - Negative electrode tab;

[0057] 12-Active substance layer;

[0058] 12a - Positive electrode active material layer;

[0059] 12b-Negative electrode active material layer;

[0060] 14 - Insulation layer;

[0061] 141 - Part One;

[0062] 142 - Part Two;

[0063] 15 - Boundary Line;

[0064] 2-Separation membrane;

[0065] X - Electrode width direction;

[0066] Y - the length direction of the electrode;

[0067] Z - Electrode thickness direction.

[0068] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Detailed Implementation

[0069] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0070] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0071] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0072] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0073] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when it is mentioned that an element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0074] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application may include a battery module or a battery pack. A battery generally includes a housing for encapsulating one or more battery cells. The housing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0075] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly consists of a positive electrode, a negative electrode, and a separator. The battery cell primarily functions by the movement of metal ions between the positive and negative electrodes. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector, and the uncoated positive current collector protrudes beyond the coated one, serving as the positive electrode tab. The negative electrode includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector, and the uncoated negative current collector protrudes beyond the coated one, serving as the negative electrode tab. To ensure that large currents can be carried without melting, multiple positive electrode tabs and multiple negative electrode tabs are stacked together.

[0076] In existing technologies, an active material layer and an insulating layer are typically coated on the current collector of the electrode in a battery cell. The active material layer and the insulating layer are not the same color. After coating, the width of the active material layer is determined by visually identifying the boundary between the active material layer and the insulating layer.

[0077] The applicant discovered that during the simultaneous coating of the active material layer and the insulating layer, the active material layer and the insulating layer would interpenetrate and blend at the boundary during the drying process, and the insulating layer would penetrate into the surface of the active material layer, resulting in a blurred boundary between the active material layer and the insulating layer after final drying.

[0078] In a single battery cell, the active material of the negative electrode must completely cover the active material of the positive electrode; that is, the active material layer of the negative electrode must be wider than that of the positive electrode to avoid lithium plating. During the drying process, the active material layer and the insulating layer interpenetrate and mix, creating blurred boundaries. This can lead to misjudgment of the active material layer's position, potentially resulting in the positive electrode not being completely covered by the negative electrode within the electrode assembly. This can cause lithium plating at that location in the battery cell, affecting its performance.

[0079] Based on the aforementioned problems identified by the applicant, the applicant has improved the coating structure of the active material layer and the insulating layer of the battery electrode by partially overlapping the active material layer and the insulating layer to solve the above problems. The embodiments of this application are further described below.

[0080] Figure 1 This is a schematic diagram of the structure of the electrical device provided in this application in a specific embodiment.

[0081] like Figure 1As shown, this application provides a battery B and an electrical device using battery B as a power source. The electrical device using battery B as a power source includes vehicles, ships, small aircraft, etc. This device uses battery B to provide electrical energy, generating the driving force to power the device. The device can also simultaneously use electrical energy and other types of energy (such as fossil fuels) to jointly generate the driving force. Any device that can use battery B as a power source is within the scope of protection of this application.

[0082] like Figure 1 As shown, taking vehicle A as an example, the electrical device can be a new energy vehicle, such as a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle. For example, vehicle A includes a motor M, a controller C, and a battery B. The battery B is horizontally positioned at the bottom of the vehicle body. The controller C controls the battery B to supply power to the motor M. The motor M is connected to the wheels on the vehicle body through a transmission mechanism, thereby driving vehicle A.

[0083] To meet diverse power demands, battery B may comprise multiple individual battery cells D. These cells D can be connected in series, parallel, or a combination of both. Battery B can also be referred to as a battery pack. Optionally, the individual battery cells D can first be connected in series, parallel, or a combination of both to form a battery module, and then these battery modules can be connected in series, parallel, or a combination of both to form battery B. In other words, the individual battery cells D can directly form battery B, or they can first be assembled into battery modules, and then the battery modules can be assembled into battery B.

[0084] Figure 2 This is an exploded view of battery B in some embodiments of this application.

[0085] like Figure 2 As shown, battery B includes a casing F and a battery cell D, with battery cell D housed within casing F. Casing F can have various shapes, such as a cylinder or cuboid. Of course, casing F can also have various structures.

[0086] In some embodiments, the housing F may include an upper housing F1 and a lower housing F2, which cover each other to define a receiving space for accommodating the battery cell D.

[0087] In battery B, there can be one or more battery cells D. If there are multiple battery cells D, they can be connected in series, in parallel, or in a mixed manner. A mixed connection means that multiple battery cells D are connected in both series and parallel.

[0088] Figure 3 This is an exploded view of a battery cell D according to some embodiments of this application.

[0089] like Figure 3As shown, a typical battery cell D includes an electrode assembly 100, a housing 200, and an end cap assembly 300. The end cap assembly 300 closes to the opening of the housing 200, providing a sealed space for the electrode assembly 100 and the electrolyte. The housing 200 can have various shapes, such as a cylinder or a cuboid. The shape of the housing 200 is determined based on the specific shape of the electrode assembly 100. For example, if the electrode assembly 100 is a cylindrical structure, the housing 200 can be a cylindrical structure; if the electrode assembly 100 is a cuboid structure, the housing 200 can be a cuboid structure. It is understood that the shape of the housing 200 can also differ from the shape of the electrode assembly 100.

[0090] For example, in Figure 3 In this embodiment, the shell 200 is a hollow cuboid structure with one open end. The shell 200 can be made of various materials, such as plastic, copper, iron, aluminum, stainless steel, aluminum alloy, etc., and this application embodiment does not impose any special restrictions on this.

[0091] like Figure 3 As shown, the end cap assembly 300 is used to close the opening of the housing 200. When assembling the battery cell D, the electrode assembly 100 is first placed inside the housing 200, and then the electrode assembly 100 is electrically connected to and fixed to the end cap assembly 300. Finally, the end cap assemblies 300 on both sides are fixedly connected to the housing 200 to complete the assembly of the battery cell D.

[0092] Figure 4 This is a cross-sectional schematic diagram of an electrode assembly 100 according to a specific embodiment of this application.

[0093] like Figure 4 As shown, in a specific embodiment of this application, the electrode assembly 100 is formed by winding a battery electrode 1 and a separator 2. The battery electrode 1 includes a positive electrode 1a and a negative electrode 1b, and the separator 2 is an insulator between the positive electrode 1a and the negative electrode 1b.

[0094] Figure 5 for Figure 4 A partial schematic diagram of the EE-direction cross-sectional view of the electrode assembly 100.

[0095] like Figure 5 As shown, the positive electrode 1a includes a positive current collector 11a and a positive active material layer 12a. The positive current collector 11a includes a coated area and an uncoated area. The positive active material layer 12a is coated on the surface of the coated area of ​​the positive current collector 11a. Along the width direction X of the electrode, the uncoated area of ​​the positive current collector 11a protrudes from the coated area to form a positive electrode tab 111a (see...). Figure 6Taking a lithium-ion battery as an example, the material of the positive electrode current collector 11a can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. Along the thickness direction Z of the electrode sheet, the positive electrode active material layer 12a can be coated on only one surface of the positive electrode current collector 11a, or the positive electrode active material layer 12a can be coated on both surfaces of the positive electrode current collector 11a simultaneously. Figure 4 The positive current collector 11a shown in the figure is coated with a positive active material layer 12a on both surfaces.

[0096] The negative electrode 1b includes a negative current collector 11b and a negative active material layer 12b. The negative current collector 11b includes a coated area and an uncoated area. The negative active material layer 12b is coated on the surface of the negative current collector 11b. Along the width direction X of the electrode, the uncoated area of ​​the negative current collector 11b protrudes from the coated area to form a positive electrode tab 111b (see...). Figure 6 The negative electrode current collector 11b can be made of copper, and the negative electrode active material can be carbon or silicon, etc. Along the electrode thickness direction Z, the negative electrode active material layer 12b can be coated on only one surface of the negative electrode current collector 11b, or it can be coated on both surfaces of the negative electrode current collector 11b simultaneously. Figure 4 The negative electrode current collector 11b shown in the figure is coated with the positive electrode active material layer 12a on both surfaces.

[0097] Figure 6 This is a partial comparative view of the positive electrode 1a and the negative electrode 1b of some embodiments of this application.

[0098] In some embodiments, the electrode assembly 100 is formed by winding a positive electrode 1a and a negative electrode 1b, and a separator 2 between the positive electrode 1a and the negative electrode 1b. When the electrode assembly 100 is unfolded, it forms a structure in which the positive electrode 1a, the separator 2, and the negative electrode 1b are stacked. Figure 5 The image shows a partial schematic diagram of the unfolded positive electrode 1a and negative electrode 1b in the electrode assembly 100. To clearly illustrate the dimensional relationship between the positive electrode 1a and the negative electrode 1b, Figure 6 The unfolded separator 2 is not shown in the figure, and part of the negative electrode 1b has been removed to the right of the dotted line in order to show the size and state of the positive electrode 1a.

[0099] like Figure 6As shown, the positive electrode 1a is coated with a positive active material layer 12a in the coating area, and the uncoated area forms a positive electrode tab 111a. The positive electrode tabs 111a are spaced apart along the length Y of the electrode. When the electrode assembly 100 is wound, multiple positive electrode tabs 111a are overlapped. The negative electrode 1b is coated with a negative active material layer 12b in the coating area, and the uncoated area forms a negative electrode tab 111b. The negative electrode tabs 111b are spaced apart along the length Y of the electrode. When the electrode assembly 100 is assembled, multiple negative electrode tabs 111b are overlapped. Figure 6 The full length of the positive electrode 1a and the negative electrode 1b is not shown, nor are all of the positive electrode tabs 111a and 111b shown.

[0100] Along the width direction X of the electrode, the negative active material layer 12b of the negative electrode 1b must cover the positive active material layer 12a of the positive electrode 1a. That is, the width H1 of the positive active material layer 12a must be smaller than the width H2 of the negative active material layer 1b, so that the positive active material layer 12a and the negative active material layer 1b maintain at least a width difference ΔH. To meet the performance requirements of the battery, the width difference ΔH is generally required to satisfy 0≤ΔH≤2.5mm, thereby ensuring that the negative active material layer 12b of the negative electrode 1b covers the positive active material layer 12a and reducing the risk of lithium plating problems.

[0101] Figure 7 This is a cross-sectional view of battery electrode 1 in one embodiment.

[0102] like Figure 7 As shown, in one specific embodiment, the current collector 11 of the battery electrode 1 of this application is coated with an active material layer 12 and an insulating layer 14 on both sides of the electrode thickness direction Z. This is just an example, and the active material layer 12 and the insulating layer 14 can also be coated on only one surface of the current collector 11.

[0103] In some embodiments, the battery electrode 1 includes a current collector 11. At least one side of the current collector 11 includes a connected uncoated area and a coated area. The coated area is coated with an active material layer 12 and an insulating layer 14. The insulating layer 14 is located on the side of the active material layer 12 closest to the uncoated area. The uncoated area forms a tab 111. The battery electrode 1 can be a positive electrode 1a or a negative electrode 1b. Both the positive electrode 1a and the negative electrode 1b can be adapted to the structures in the following embodiments. When the battery electrode 1 is a positive electrode 1a, the current collector 11 is a positive current collector 11a, and the tab 111 is a positive tab 111a. When the battery electrode 1 is a negative electrode 1b, the current collector 11 is a negative current collector 11b, and the tab 111 is a negative tab 111b.

[0104] like Figure 7As shown, the insulating layer 14 includes a first portion 141 and a second portion 142 connected together. The second portion 142 is located in the edge region of the insulating layer 14 near the active material layer 12. The active material layer 12 is configured to cover the second portion 142 but not the first portion 141, so that the active material layer 12 overlaps with the projection portion of the insulating layer 14 along the electrode thickness direction Z.

[0105] The edge of the active material layer 12 is connected to the first portion 141, forming a boundary line 15. The second portion 142 is covered by the active material layer 12, and the second portion 142 does not penetrate to the upper surface of the active material layer 12, so that the boundary line is not blurred due to the mixing of coating paste in the edge area of ​​the insulating layer 14 near the active material layer 12, thus forming a clear boundary line 15.

[0106] Figure 8 for Figure 7 Enlarged view of Part I.

[0107] like Figure 8 As shown, along the electrode thickness direction Z, the thickness w1 of the insulating layer 14 is not greater than the thickness w2 of the active material layer 12, i.e., w1 ≤ w2. In this embodiment, the thickness w1 of the insulating layer 14 refers to the maximum thickness of the insulating layer 14. The preferred range of the thickness w2 of the active material layer 12 is 50-400 micrometers (μm), and the preferred range of the thickness w1 of the insulating layer is 3-90 μm. When the active material layer 12 covers the second part 142, the coating slurry of the second part 142 is in contact with the coating slurry inside the active material layer 12. Due to the large thickness difference between the thickness w2 of the active material layer 12 and the thickness w1 of the insulating layer 14, even if the coating slurry of the second part 142 mixes with the coating slurry inside the active material layer 12, the mixed slurry will not seep out to the upper surface of the active material layer 12.

[0108] In one specific embodiment, the thickness w4 of the first part 141 is the maximum thickness of the insulating layer 14, i.e., w4 = w1.

[0109] The thickness w3 of the second part 142 is not greater than the thickness w4 of the first part 141, i.e., w3 ≤ w4. The thickness w3 of the second part 142 is less than the thickness w4 of the first part 141 outside the exposed active material layer 12, so that the second part 142 with a smaller thickness extends into the active material layer 12. The smaller thickness w3 of the second part will not cause the coating thickness of the area of ​​the active material layer 12 covering the second part 142 to increase significantly and form a bulging edge, thereby ensuring that the overall thickness of the battery electrode 1 is consistent. When the coated battery electrode 1 is wound into an electrode roll, the risk of the battery electrode 1 bursting and breaking during winding due to the presence of a bulging edge is reduced.

[0110] Along the thickness direction Z of the electrode, the shortest distance w5 between the surface of the second portion 142 facing the current collector 11 and the surface of the current collector 11 should satisfy 0 ≤ w5 ≤ 0.9 × w2, that is, the shortest distance w5 between the surface of the second portion 142 facing the current collector 11 and the surface of the current collector 11 should be less than or equal to 0.9 times the thickness w2 of the active material layer 12. In a specific embodiment, the shortest distance w5 between the surface 1421 of the second portion 142 facing the current collector 11 and the surface of the current collector 11 is 0-90 μm.

[0111] The surface of the second part 142 facing the current collector 11 is the lower surface of the second part 142 along the electrode thickness direction Z, and the surface of the second part 142 away from the current collector 11 is the upper surface of the second part 142 along the electrode thickness direction Z.

[0112] The second part 142 extends into the active material layer 12. The active material layer 12 can cover the upper and lower surfaces of the second part 142 along the electrode thickness direction Z, as well as the end face of the second part 142 extending into the active material layer 12 along the electrode width direction X. Alternatively, the active material layer 12 can only cover the upper surface and end face of the second part 142 along the electrode thickness direction Z. In this case, the shortest distance w5 between the surface of the second part 142 facing the current collector 11 and the surface of the current collector 11 is 0, that is, the surface of the second part 142 facing the current collector 11 is directly coated on the current collector 11.

[0113] The setting of the shortest distance w5 between the surface of the second part 142 facing the current collector 11 and the surface of the current collector 11 ensures that the second part 142 is close enough to the current collector 11 and far away from the outer surface of the active material layer 12, thereby reducing the possibility of the coating slurry of the second part 142 penetrating to the outer surface of the active material layer 12.

[0114] In some embodiments, along the electrode thickness direction Z, the distance w6 between the surface of the second portion 142 away from the current collector 11 and the outer surface of the active material layer 12 should satisfy 0.01×w2≤w6≤0.9×w2. In one specific embodiment, the distance w6 between the surface of the second portion 142 away from the current collector 11 and the outer surface of the active material layer 12 is not less than 20μm.

[0115] The distance w6 between the surface of the second part 142 away from the current collector 11 and the outer surface of the active material layer 12 is set to ensure that the second part 142 is sufficiently away from the outer surface of the active material layer 12, thereby reducing the possibility of the coating slurry of the second part 142 penetrating to the outer surface of the active material layer 12.

[0116] In some embodiments, the thickness w3 of the second portion 142 should satisfy 0.01×w2≤w3≤0.9×w2. In one specific embodiment, the thickness w3 of the second portion 142 is 3-90μm.

[0117] By setting the thickness w3 of the second part 142 to be relatively small, the coating thickness variation in the overlapping area between the active material layer 12 and the second part 142 will also be relatively small. This will prevent the coating thickness in the overlapping area between the active material layer 12 and the insulating layer 142 from increasing significantly and forming a bulging edge. This ensures that the overall thickness of the battery electrode 1 is consistent, and reduces the risk of bulging edges of the battery electrode 1 when the battery electrode 1 is wound into the electrode assembly 100.

[0118] Typically, tab 111 is obtained by die-cutting the substrate of battery electrode 1. The die-cutting position of tab 111 needs to be located on insulating layer 14. Therefore, insulating layer 14 needs to have a certain width. In some embodiments, the width L1 of the first part 141 is in the range of 0.1-15 mm to ensure that the die-cutting position of tab 111 is located on the first part 141.

[0119] Along the direction in which the active material layer 12 and the insulating layer 14 are arranged (electrode width direction X), the width L2 of the second portion 142 is not greater than the width L1 of the first portion 141, i.e., L2 ≤ L1. In some embodiments, the width L2 of the second portion 142 is in the range of 0.01-2 mm, ensuring that the projections of the active material layer 12 and the second portion 142 in the electrode thickness direction Z overlap, while avoiding excessive overlap between the second portion 142 and the first coating layer 12.

[0120] Figure 9 This is a cross-sectional view of battery electrode 1 in another embodiment.

[0121] like Figure 9 As shown, in some embodiments, the surface of the second portion 142 away from the current collector 11 is a slope 1421, and the slope 1421 gradually approaches the current collector 11 along the direction in which the first portion 141 extends toward the active material layer 12. At this time, the projection of the active material layer 12 along the electrode thickness direction overlaps with the second portion 142, and the thickness w3 of the second portion 142 gradually decreases from the position where it intersects with the first portion 141 in the opposite direction of the electrode width direction X, reducing the risk of increased total coating thickness and bulging edges in the overlapping area of ​​the active material layer 12 and the second portion 142. Furthermore, after simultaneously coating the active material layer 12 and the second portion 142, during the coating drying process, the active material layer 12 shrinks and slides along the inclined slope 1421, reducing the penetration and mixing of the coating slurry of the second portion 142 into the active material layer 12.

[0122] Figure 9 In the example, along the electrode thickness direction Z, the thickness w4 of the first part 141 is equal to the thickness w2 of the active material layer.

[0123] Figure 10This is a cross-sectional view of battery electrode 1 in yet another embodiment.

[0124] like Figure 10 As shown, in some embodiments, the surface of the second portion 142 away from the current collector 11 is a slope 1421, and along the electrode thickness direction Z, the thickness w4 of the first portion 141 is less than the thickness w2 of the active material layer. In these embodiments, since the insulating layer 14 has a smaller thickness than the active material layer 12, the problem of a significant increase in coating thickness and the formation of bulging edges in the overlapping area of ​​the active material layer 12 and the insulating layer 142 caused by coating slurry mixing can be reduced.

[0125] Of course, the shape of the second part 142 in this application is not limited to the situation described in the above embodiments, and it can be a combination of various structural shapes in the embodiments of this application.

[0126] The battery electrode 1 provided in this application is coated with an active material layer 12 and an insulating layer 14. The insulating layer 14 includes a first portion 141 and a second portion 142 connected together. The second portion 142 is located in the edge region of the insulating layer 14 near the active material layer 12. The active material layer 12 is configured to cover the second portion 142 so that the active material layer 12 and the insulating layer 14 overlap in the projection portion along the thickness direction Z of the electrode. The second portion 142 does not penetrate to the upper surface of the active material layer 12, and there is no problem of interface blurring due to coating slurry mixing in the edge region of the insulating layer 14 near the active material layer 12, thereby forming a clear boundary line 15.

[0127] Using the electrode assembly 100, battery cell D, and battery B composed of the battery electrode 1 of this application, it is possible to ensure that the negative electrode 1b covers the positive electrode 1a, thereby reducing the risk of lithium plating in the battery and improving the safety performance of the battery.

[0128] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery electrode, characterized in that, The battery electrode includes a current collector. The current collector includes at least one connected coated area and uncoated area. The coated area is coated with an active material layer and an insulating layer, and the insulating layer is located on the side of the active material layer closer to the uncoated area. The insulating layer includes a first portion and a second portion connected together. The second portion is located in the edge region of the insulating layer near the active material layer. The active material layer is configured to cover the second portion but not the first portion, so that the active material layer and the insulating layer partially overlap along the electrode thickness direction. The maximum thickness of the insulating layer is less than the maximum thickness of the active material layer. The surface of the second portion away from the current collector is an inclined surface, and the inclined surface gradually approaches the current collector along the direction extending from the first portion toward the active material layer.

2. The battery electrode according to claim 1, characterized in that, Along the direction in which the active material layer and the insulating layer are arranged, the maximum width of the second portion is less than or equal to the maximum width of the first portion.

3. An electrode assembly, characterized in that, Includes the battery electrode as described in claim 1 or 2.

4. A single battery cell, characterized in that, Includes the electrode assembly as described in claim 3.

5. A battery, characterized in that, It includes multiple battery cells as described in claim 4.

6. An electrical device, characterized in that, Includes the battery as described in claim 5, wherein the battery is used to provide electrical energy.

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