Electrode plate, electrode assembly and electrochemical device

Abstract

The invention relates to the technical field of batteries, and discloses a pole piece, an electrode assembly and an electrochemical device. A current collector of the pole piece comprises a supporting layer, and a first conductive layer and a second conductive layer which are arranged on two sides of the supporting layer, and the current collector comprises a first main body part and a first convex part; the active material layer is arranged on the first main body part; the first tab unit is locally welded on the first conductive layer of the first convex part through a first welding mark; the second tab unit is locally welded on the second conductive layer of the first convex part through a second welding mark; the insulating part is arranged on the first convex part and covers the first welding mark and the second welding mark, the width of the insulating part in the third direction is larger than that of the first tab unit, and the width of the insulating part in the third direction is larger than that of the second tab unit. And the insulating part can cover the first tab unit and the second tab unit in the third direction, so that short circuit in the pole piece caused by exposure of the first tab unit and the second tab unit due to heat shrinkage of the insulating part is avoided, and the safety performance of the electrochemical device is improved.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of battery technology, and in particular to a pole piece, an electrode assembly, and an electrochemical device. Background Art

[0002] The pole piece in the electrode assembly adopts a metal-polymer-metal three-layer sandwich composite current collector structure, which can effectively reduce the thickness of the metal layer of the current collector, thereby improving the weight energy density of the electrochemical device. Since the metal layer in the composite current collector is relatively thin, the pole ear unit is generally welded on the composite current collector by roller welding and glue coating at the same time, so that the pole ear unit can be welded to the transfer pole ear, which improves the reliability of welding. However, during the use of the electrochemical device, the glue coating is prone to shrinkage, resulting in the pole ear unit being exposed, which poses a certain safety risk. Summary of the invention

[0003] The present application provides a pole piece, an electrode assembly and an electrochemical device, which can effectively solve the problem that the glue coating is easy to shrink and expose the pole ear unit, thereby improving the safety performance of the electrochemical device.

[0004] An embodiment of the present application provides a pole piece including a current collector, an active material layer, a first pole lug unit, a second pole lug unit and an insulating component. The current collector includes a support layer, and a first conductive layer and a second conductive layer arranged on both sides of the support layer along a first direction, the first direction is the thickness direction of the current collector, and the current collector includes a first main body and a first convex portion connected to each other along a second direction, and along a third direction, the width of the first convex portion is less than the width of the first main body, and the first direction, the second direction and the third direction are perpendicular to each other; the active material layer is arranged on the first main body, and in the first direction, at least one of the surface of the first conductive layer away from the support layer and the surface of the second conductive layer away from the support layer is provided with the active material layer; the first pole lug unit extends along the second direction, the first pole lug unit is partially welded to the first conductive layer on the first convex portion, and the first pole lug unit and the first conductive layer form a first weld mark; the second pole lug unit extends along the second direction, the second pole lug unit is partially welded to the second conductive layer on the first convex portion, and the second pole lug unit and the second conductive layer form a second weld mark; the insulating component is arranged on the first convex portion, the insulating component covers the first weld mark and the second weld mark at the same time, along the third direction, the width of the insulating component is greater than the first pole lug unit, and along the third direction, the width of the insulating component is equal to the width of the second pole lug unit. The pole piece of the present application is achieved by setting the width of the insulating component to be greater than the width of the first pole lug unit and the width of the second pole lug unit, that is, both ends of the insulating component in the third direction extend beyond the first pole lug unit and the second pole lug unit. In this way, in a high-temperature environment, the insulating component can effectively wrap the first pole lug unit and the second pole lug unit even if it shrinks, avoiding exposure of the first pole lug unit and the second pole lug unit, thereby improving the safety performance of the electrochemical device.

[0005] In some embodiments, the insulating component includes a first protective layer and a second protective layer, the first protective layer is disposed on the surface of the first tab unit away from the first conductive layer and covers the first weld mark, along the third direction, the first protective layer has a first end and a second end opposite to each other, the first end exceeds the first side edge, and the second end exceeds the second side edge; the second protective layer is disposed on the surface of the second tab unit away from the second conductive layer and covers the second weld mark, along the third direction, the second protective layer has a third end and a fourth end opposite to each other, the third end exceeds the first side edge, and the fourth end exceeds the second side edge; the first end is connected to the third end edge, and the second end is connected to the fourth end edge. By adopting a structure in which the first protective layer and the second protective layer are simultaneously bonded and connected up and down, on the one hand, the difficulty of the insulating component wrapping the circumferential periphery of the first tab unit, the first convex portion, and the second tab unit can be effectively reduced, and the production efficiency can be improved; on the other hand, both ends of the first protective layer and the second protective layer exceed the first tab unit, so that the ends of the first protective layer and the second protective layer that exceed the first tab unit can be easily bonded and connected, thereby forming a closed structure, and preventing the first protective layer and the second protective layer from shrinking due to heat, causing the edge of the first tab unit or the second tab unit to be exposed.

[0006] In some embodiments, the first protective layer and the second protective layer of the insulating component are an integrated structure, the insulating component is wound around the first pole lug unit, the second pole lug unit and the first protrusion with the second direction as the winding axis. The insulating component can be wound around the first pole lug unit, the second pole lug unit and the first protrusion in a circumferential direction in a high temperature environment by the above-mentioned winding method, so as to prevent the first pole lug unit, the first protrusion and the second pole lug unit from being exposed.

[0007] In some embodiments, along the first direction, the thickness H1 of the first protective layer satisfies: 10um≤H1≤50um; and / or, along the first direction, the thickness H2 of the second protective layer satisfies: 10um≤H2≤50um. If the thickness of the first protective layer and the second protective layer is too thin, it is easy to be punctured by the tip or burr of the first weld mark and the second weld mark, resulting in insulation failure; if the thickness of the first protective layer and the second protective layer is too thick, the thickness of the electrode in the area wrapped with the insulating component will be too thick, thereby reducing the energy density of the electrochemical device.

[0008] In some embodiments, 15um≤H1≤25um; and / or, 15um≤H2≤25um. By setting the thickness of the first protective layer and the thickness of the second protective layer within the above range, the thickness of the first protective layer and the second protective layer can be reduced as much as possible while meeting the insulation requirements, thereby reducing the occupied space and improving the energy density of the electrochemical device.

[0009] In some embodiments, when viewed along the first direction, in the third direction, the width of the first pole lug unit is equal to the width of the first protrusion, and / or, in the third direction, the width of the second pole lug unit is equal to the width of the first protrusion. By setting the width of the first pole lug unit and / or the second pole lug unit to be equal to the width of the first protrusion, when the edge of the insulating component exceeds the edge of the first pole lug unit in the third direction, the insulating component can cover and wrap the first protrusion, avoiding the first protrusion from being exposed, and preventing the internal short circuit of the pole piece.

[0010] In some embodiments, when observed along the first direction, in the third direction, the width K1 of the first pole lug unit satisfies: 5mm≤K1≤20mm; in the second direction, the length L1 of the first pole lug unit satisfies: 5mm≤L1≤20mm. In the third direction, the width K2 of the second pole lug unit satisfies: 5mm≤K2≤20mm; in the second direction, the length L2 of the second pole lug unit satisfies: 5mm≤L2≤20mm. If the width K1 of the first pole lug unit and the width K2 of the second pole lug unit are too small, the current flow capacity is too poor and it is easy to break. If they are too large, they occupy the internal space of the electrochemical device and reduce the energy density. If the length L1 of the first pole lug unit and the length L2 of the second pole lug unit are too short, they cannot be welded with the transfer pole lug. If they are too long, it will hinder welding and occupy the space inside the electrochemical device and reduce the energy density.

[0011] In some embodiments, 7mm≤K1≤9mm, 9mm≤L1≤11mm; and / or, 7mm≤K2≤9mm, 9mm≤L2≤11mm. By setting the width of the first tab unit and the second tab unit within the above range, the current capacity and occupied space of the first tab unit and the second tab unit can be further balanced, while also helping to enhance the connection strength of the first tab unit and the second tab unit with the first protrusion by roll-welding. By setting the length of the first tab unit and the second tab unit within the above range, the difficulty of welding the first tab unit and the second tab unit with the transfer tab can be further reduced.

[0012] In some embodiments, when viewed along the first direction, the first pole lug unit has a first side and a second side in the third direction, and the insulating component has a third side and a fourth side, wherein the first side and the third side are located on the same side of the first pole lug unit, and the second side and the fourth side are located on the other same side of the first pole lug unit; along the third direction, the distance L3 between the first side and the third side satisfies: 0.5mm≤L3≤2mm; and / or, along the third direction, the distance L4 between the second side and the fourth side satisfies: 0.5mm≤L4≤2mm. Setting the distance that one side of the insulating component exceeds one side of the first pole lug unit to 0.5mm to 2mm can ensure that the edge of the insulating component can exceed the edge of the first pole lug unit, so that the insulating component will not cause the edge of the first pole lug unit to be exposed when heated, and will not cause the redundant length to be too long, thereby ensuring that the electrochemical device has a higher energy density.

[0013] In some embodiments, 0.8 mm ≤ L3 ≤ 1.2 mm; and / or, 0.8 mm ≤ L4 ≤ 1.2 mm. The distance that one side of the insulating component exceeds one side of the first tab unit is set to 0.8 mm to 1.2 mm, so that the length of the insulating component exceeding the first tab unit in the third direction can be reduced as much as possible while ensuring that the edge of the insulating component can be effectively bonded, thereby further improving the electrochemical device to have a higher energy density.

[0014] In some embodiments, the insulating component includes at least one of polyethylene terephthalate, polypropylene, and polyimide. The insulating component is made of the above materials. On the one hand, the insulating component can have good insulation properties, thereby avoiding insulation failure of the first tab unit and the second insulating unit at the first weld mark and the second weld mark. In addition, the above materials have good heat resistance. In a high temperature environment, the insulating component is not easy to shrink and the shrinkage is small, thereby ensuring that the insulating component can effectively cover the first tab unit and the second tab unit; on the other hand, the thickness of the insulating component can be made relatively thin, for example, the insulating component can be an insulating tape, thereby greatly reducing the thickness of the insulating component.

[0015] Another technical solution adopted in the embodiment of the present application is: to provide an electrode assembly, including the above-mentioned electrode piece.

[0016] Another technical solution adopted in the embodiment of the present application is: to provide an electrochemical device including an electrode assembly.

[0017] The pole piece of the embodiment of the present application includes a current collector, an active material layer, a first pole lug unit, a second pole lug unit and an insulating component. The current collector includes a support layer, and a first conductive layer and a second conductive layer arranged on both sides of the support layer along a first direction, the first direction is the thickness direction of the current collector, and the current collector includes a first main body and a first convex portion connected to each other along a second direction, and along a third direction, the width of the first convex portion is less than the width of the first main body, and the first direction, the second direction and the third direction are perpendicular to each other; the active material layer is arranged on the first main body, and in the first direction, at least one of the surface of the first conductive layer away from the support layer and the surface of the second conductive layer away from the support layer is provided with the active material layer; the first pole lug unit extends along the second direction, the first pole lug unit is partially welded to the first conductive layer on the first convex portion, and the first pole lug unit and the first conductive layer form a first weld mark; the second pole lug unit extends along the second direction, the second pole lug unit is partially welded to the second conductive layer on the first convex portion, and the second pole lug unit and the second conductive layer form a second weld mark; the insulating component is arranged on the first convex portion, the insulating component covers the first weld mark and the second weld mark at the same time, along the third direction, the width of the insulating component is greater than the first pole lug unit, and along the third direction, the width of the insulating component is greater than the width of the second pole lug unit. The pole piece of the present application is achieved by setting the width of the insulating component to be greater than the width of the first pole lug unit and the width of the second pole lug unit, that is, both ends of the insulating component in the third direction extend beyond the first pole lug unit and the second pole lug unit. In this way, in a high-temperature environment, the insulating component can effectively wrap the first pole lug unit and the second pole lug unit even if it shrinks, thereby avoiding the shrinkage of the insulating component to expose the first pole lug unit and the second pole lug unit, thereby improving the safety performance of the electrochemical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application, the following is a brief introduction to the drawings required for describing the specific embodiments. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0019] Figure 1 It is a schematic diagram of a pole piece according to an embodiment of the present application.

[0020] Figure 2 The pole piece of the embodiment of the present application is along Figure 1 Sectional view of AA.

[0021] Figure 3 The pole piece of the embodiment of the present application is along Figure 2 Cross-sectional view of BB.

[0022] Figure 4 Another embodiment of the present application is the pole piece along Figure 2 Cross-sectional view of BB.

[0023] 100, pole piece; 10, current collector; 11, support layer; 12, first conductive layer; 13, second conductive layer; 14, first main body; 15, first convex portion; 20, active material layer; 30, first pole lug unit; 30a, first weld mark; 31, first side; 32, second side; 40, second pole lug unit; 40a, second weld mark; 50, insulating component; 51, third side; 52, fourth side; 53, first protective layer; 531, first end; 532, second end; 54, second protective layer; 541, third end; 542, fourth end; X, first direction; Y, second direction; Z, third direction. DETAILED DESCRIPTION

[0024] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on another element or there can be one or more centered elements therebetween. When an element is described as "connected" to another element, it can be directly connected to another element or there can be one or more centered elements therebetween. The orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "vertical", "horizontal", etc. used in this specification is based on the orientation or positional relationship shown in the accompanying drawings, only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0025] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0026] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0027] The electrochemical device of the prior art includes an electrode assembly, and the pole piece in the electrode assembly adopts a metal-polymer-metal three-layer sandwich composite current collector structure, which can effectively reduce the thickness of the metal layer of the current collector, thereby improving the weight energy density of the electrochemical device. Since the metal layer in the composite current collector is relatively thin, if the pole ear unit is welded on the current collector by laser welding, it is easy to break through the metal layer and cause the composite current collector to fail. Generally, the pole ear unit is welded on the composite current collector by rolling welding and gluing at the same time, so that the pole ear unit can be welded with the transfer pole ear, thereby improving the reliability of welding. Specifically, after completing the steps of rolling welding and gluing, the rolling welding and gluing areas of the pole piece are cut to obtain the pole ear of the pole piece. However, the edge of the glue after cutting is flush with the edge of the pole ear unit. During the use of the electrochemical device, the glue is easy to shrink in a high temperature environment, resulting in the edge of the pole ear unit being exposed. The glue cannot effectively protect the pole ear unit, which is easy to cause an internal short circuit of the electrochemical device and cause failure or even explosion.

[0028] In order to solve the problem that the above-mentioned glue is easy to shrink in a high temperature environment, resulting in the exposure of the edge of the pole lug unit, in the embodiment of the present application, after the pole lug unit and the composite current collector are connected by roller welding, the pole lug unit is first cut to form the pole lug of the pole piece, and then an insulating glue layer is arranged at the weld mark of the pole lug, and the width of the insulating glue layer is made greater than the width of the pole lug unit, thereby ensuring that the insulating glue layer can still effectively wrap the pole lug unit in a high temperature environment and ensure the safety of the electrochemical device.

[0029] See also Figure 1 and Figure 2 , the pole piece 100 of the embodiment of the present application includes a current collector 10, an active material layer 20, a first pole lug unit 30, a second pole lug unit 40 and an insulating component 50. The current collector 10 includes a support layer 11, a first conductive layer 12 and a second conductive layer 13, and the first support layer 11 and the second support layer 11 are respectively arranged on both sides of the support layer 11 in the first direction X, wherein the first direction X is the thickness direction of the current collector 10. The current collector 10 includes a first main body 14 and a first convex portion 15 connected along the second direction Y, and along the third direction Z, the width of the first convex portion 15 is less than the width of the first main body 14, wherein the first direction X, the second direction Y and the third direction Z are perpendicular to each other, and in addition, the second direction Y can also be understood as the direction in which the first pole lug unit 30 mentioned below extends out of the current collector 10.

[0030] The active material layer 20 is disposed on the first main body 14 of the current collector 10. Specifically, in the first direction X, the surface of the first conductive layer 12 facing away from the support layer 11 and the surface of the second conductive layer 13 facing away from the support layer 11, at least one of the two surfaces is provided with the active material layer 20. The first convex portion 15 is in a hollow foil state, that is, the surface of the first convex portion 15 is not provided with the active material layer 20, so that the first tab unit 30 and the second tab unit 40 can be welded and fixed to the first convex portion 15. As an embodiment, the first tab unit 30 extends along the second direction Y, and a part of the first tab unit 30 is connected by roller welding so that a first weld mark 30a is formed between the first tab unit 30 and the first conductive layer 12, and the first weld mark 30a fixes the first tab unit 30 to the first conductive layer 12 of the first convex portion 15. The second pole tab unit 40 extends along the second direction Y, and a part of the second pole tab unit 40 is connected by roll welding so that a second weld mark 40a is formed between the second pole tab unit 40 and the second conductive layer 13, and the second weld mark 40a fixes the second pole tab unit 40 to the second conductive layer 13 of the first protrusion 15. The insulating component 50 is disposed on the first protrusion 15, and the insulating component 50 covers the first weld mark 30a and the second weld mark 40a at the same time, thereby protecting the diaphragm disposed adjacent to the pole piece 100, and preventing the tip or edge burrs of the first weld mark 30a and the second weld mark 40a from piercing the diaphragm, causing failure of the electrochemical device.

[0031] Along the third direction Z, the width of the insulating component 50 is greater than the width of the first pole lug unit 30, and the width of the insulating component 50 is greater than the width of the second pole lug unit 40. By setting the width of the insulating component 50 to be greater than the width of the first pole lug unit 30 and the width of the second pole lug unit 40, both ends of the insulating component 50 in the third direction Z can exceed the first pole lug unit 30 and the second pole lug unit 40, such as Figure 3 and Figure 4 As shown, in a high temperature environment, the insulating component 50 can effectively wrap the first tab unit 30 and the second tab unit 40 even if it shrinks, thereby preventing the insulating component 50 from shrinking and exposing the first tab unit 30 and the second tab unit 40, thereby improving the safety performance of the electrochemical device.

[0032] It is worth noting that, in some embodiments, when the widths of the first pole lug unit 30 and the second pole lug unit 40 in the third direction Z are inconsistent, for example, when the width of the first pole lug unit 30 is greater than the width of the second pole lug unit 40, the width of the insulating component 50 is greater than the width of the first pole lug unit 30, and when the width of the second pole lug unit 40 is greater than the width of the first pole lug unit 30, the width of the insulating component 50 is greater than the width of the second pole lug unit 40, that is, it is necessary to ensure that the width of the insulating component 50 is the largest among the widths of the first pole lug unit 30, the second pole lug unit 40 and the insulating component 50.

[0033] In some embodiments, see Figure 1 , observing the pole piece 100 along the first direction X, in the third direction Z, the width of the first pole lug unit 30 is equal to the width of the first protrusion 15, and / or, the width of the second pole lug unit 40 is equal to the width of the first protrusion 15. Among them, the equal width of the first pole lug unit 30 and the first protrusion 15 means that along the third direction Z, the edge of the first pole lug unit 30 is flush with the edge of the first protrusion 15. Similarly, the equal width of the second pole lug unit 40 and the first protrusion 15 means that along the third direction Z, the edge of the second pole lug unit 40 is flush with the edge of the first protrusion 15. It is worth noting that due to process errors, in the third direction Z, the width difference between the first pole lug unit and the first protrusion on one side is within 0.5 mm, and it can be considered that the edge of the first pole lug unit is flush with the edge of the first protrusion, that is, the above-mentioned widths are equal. Similarly, in the third direction Z, the width difference between the second pole lug unit and the first protrusion on one side is within 0.5 mm, and the edge of the second pole lug unit can be considered to be flush with the edge of the first protrusion. By setting the width of the first pole lug unit 30 and / or the second pole lug unit 40 to be equal to the width of the first protrusion 15, when the edge of the insulating component 50 exceeds the edge of the first pole lug unit 30 in the third direction Z, the insulating component 50 can cover and wrap the first protrusion 15, avoiding the first protrusion 15 from being exposed, and preventing the internal short circuit of the pole piece 100.

[0034] In some embodiments, see Figure 1, observing the pole piece 100 along the first direction X, in the third direction Z, the width K1 of the first pole tab unit 30 satisfies: 5mm≤K1≤20mm, and in the second direction Y, the length L1 of the first pole tab unit 30 satisfies: 5mm≤L1≤20mm. And / or, in the third direction Z, the width K2 of the second pole tab unit 40 satisfies: 5mm≤K2≤20mm; in the second direction Y, the length L2 of the second pole tab unit 40 satisfies: 5mm≤L2≤20mm. If the width K1 of the first pole tab unit 30 and the width K2 of the second pole tab unit 40 are too small, the current flow capacity is too poor and it is easy to break. If they are too large, the internal space of the electrochemical device is occupied and the energy density is reduced. Therefore, by setting the width K1 of the first pole tab unit 30 and the width K2 of the second pole tab unit 40 within the above-mentioned numerical range, the first pole tab unit 30 and the second pole tab unit 40 can both enhance the structural strength and ensure the current flow capacity, and ensure that the electrochemical device has a high energy density. If the length L1 of the first tab unit 30 and the length L2 of the second tab unit 40 are too short, they cannot be welded with the transfer tab. If they are too long, welding will be hindered and the space inside the electrochemical device will be occupied, thereby reducing the energy density. Therefore, by setting the length L1 of the first tab unit 30 and the length L2 of the second tab unit 40 within the above numerical range, the first tab unit 30 and the second tab unit 40 can be smoothly welded with the transfer tab without occupying too much space, so that the electrochemical device has a higher energy density.

[0035] Further, in the third direction Z, the width K1 of the first pole lug unit 30 satisfies: 7mm≤K1≤9mm, and in the second direction Y, the length L1 of the first pole lug unit 30 satisfies: 9mm≤L1≤11mm. And / or, in the third direction Z, the width K2 of the second pole lug unit 40 satisfies: 7mm≤K2≤9mm; in the second direction Y, the length L2 of the second pole lug unit 40 satisfies: 9mm≤L2≤11mm. By setting the widths of the first pole lug unit 30 and the second pole lug unit 40 within the above range, the occupied space of the current capacity of the first pole lug unit 30 and the second pole lug unit 40 can be further balanced, and it is also helpful to enhance the connection strength of the first pole lug unit 30 and the second pole lug unit 40 and the first protrusion 15 by roll-welding. By setting the lengths of the first pole lug unit 30 and the second pole lug unit 40 within the above range, the difficulty of welding the first pole lug unit 30 and the second pole lug unit 40 to the transfer pole lug can be further reduced.

[0036] In some embodiments, see Figure 1, observing the pole piece 100 along the first direction X, in the third direction Z, the first pole lug unit 30 has a first side 31 and a second side 32, and the insulating component 50 has a third side 51 and a fourth side 52, wherein the first side 31 and the third side 51 are located on the same side of the first pole lug unit 30 and the third side 51 is on the outside, and the second side 32 and the fourth side 52 are located on the other same side of the first pole lug unit 30 and the fourth side 52 is on the outside. Along the third direction Z, the distance L3 between the first side 31 and the third side 51 satisfies: 0.5mm≤L3≤2mm; the distance L4 between the second side 32 and the fourth side 52 satisfies: 0.5mm≤L4≤2mm. If the distance that one side of the insulating component 50 exceeds one side of the first pole lug unit 30 in the third direction Z is too short, the problem that the insulating component 50 shrinks when heated, resulting in the exposure of the first pole lug unit 30 and the second pole lug unit 40 cannot be effectively solved. In addition, as described below, when both ends of the insulating component 50 are sticky, the distance that the insulating component 50 exceeds one side is too short, resulting in the inability to effectively close the edges of the first protective layer 53 and the second protective layer 54 (effectively bonded), and the insulating component 50 will still shrink in a high-temperature environment, resulting in partial exposure of the first pole lug unit 30; if the distance that one side of the insulating component 50 exceeds one side of the first pole lug unit 30 in the third direction Z is too long, the redundant length of the insulating component 50 is too long, and the redundant insulating component 50 is too long. The component 50 can be easily inserted upside down into the electrode piece 100 or into the electrode assembly, posing a safety risk to the electrochemical device. The active material layer corresponding to the position where the insulating component 50 is inserted upside down cannot normally participate in the electrochemical reaction, thereby reducing the energy density of the electrochemical device. At the same time, if the edge of the insulating component 50 is too long, it will increase the weight of the electrode piece 100, occupy too much internal space, and reduce the energy density of the electrochemical device. Therefore, setting the distance where one side of the insulating component 50 exceeds one side of the first electrode lug unit 30 to 0.5 mm to 2 mm can ensure that the insulating component 50 can effectively cover the first electrode lug unit 30 and the second electrode lug unit 40 without causing excessive redundant length, thereby ensuring that the electrochemical device has a higher energy density.

[0037] Furthermore, along the third direction Z, the distance L3 between the first side 31 and the third side 51 satisfies: 0.8mm≤L3≤1.2mm; the distance L4 between the second side 32 and the fourth side 52 satisfies: 0.8mm≤L4≤1.2mm. The distance that one side of the insulating component 50 exceeds one side of the first tab unit 30 is set to 0.8mm to 1.2mm. When the end of the insulating component 50 in the third direction Z is sticky, the difficulty of bonding the end of the first protective layer 53 and the end of the second protective layer 54 can be reduced, and the length of the insulating component 50 in the third direction Z that exceeds the first tab unit 30 can be reduced as much as possible, thereby further improving the energy density of the electrochemical device.

[0038] In some embodiments, see Figure 4 , observing the pole piece 100 along the second direction Y, the insulating component 50 includes a first protective layer 53 and a second protective layer 54. The first protective layer 53 is arranged on the surface of the first pole tab unit 30 away from the first conductive layer 12 and covers the first weld mark 30a. Along the third direction Z, the first protective layer 53 has a first end 531 and a second end 532 opposite to each other, wherein the first end 531 constitutes the third side 51 of the insulating component 50, and the second end 532 constitutes the fourth side 52 of the insulating component 50. Along the third direction Z, the first end 531 exceeds the first side 31, and the second end 532 exceeds the second side 32. The second protective layer 54 is arranged on the surface of the second pole tab unit 40 away from the second conductive layer 13 and covers the second weld mark 40a. Along the third direction Z, the second protective layer 54 has a third end 541 and a fourth end 542 opposite to each other, wherein the third end 541 constitutes the third side 51 of the insulating component 50, and the fourth end 542 constitutes the fourth side 52 of the insulating component 50. Along the third direction Z, the third end 541 exceeds the first side 31, and the fourth end 542 exceeds the second side 32. By configuring the insulating component 50 as an independent first protective layer 53 and a second protective layer 54, the difficulty of configuring the insulating component 50 on the first tab unit 30 and the second tab unit 40 during the production process can be reduced, thereby facilitating mechanized assembly production.

[0039] In some embodiments, the first end 531 and the second end 532 of the first protective layer 53 are non-sticky, and the third end 541 and the fourth end 542 of the second protective layer 54 are non-sticky. That is, the two ends of the first protective layer 53 and the two ends of the second protective layer 54 are in a freely extended state, and the extended length of the first end 531 and the second end 532 relative to the first pole lug unit 30 is greater than the contracted length of the first pole lug unit 30 when heated, and the extended length of the third end 541 and the fourth end 542 relative to the second pole lug unit 40 is greater than the contracted length of the second pole lug unit 40 when heated, so that the first pole lug unit 30 and the second pole lug unit 40 can be always wrapped by the insulating component 50 in the third direction.

[0040] In some embodiments, at least the first end 531 and the second end 532 of the first protective layer 53 are adhesive, and at least the third end 541 and the fourth end 542 of the second protective layer 54 are adhesive, the first end 531 and the third end 541 are bonded and connected to each other, and the second end 532 and the fourth end 542 are bonded and connected to each other. By adopting a structure in which the first protective layer 53 and the second protective layer 54 are bonded and connected at the same time, the difficulty of the insulating component 50 wrapping the circumferential periphery of the first tab unit 30, the first protrusion 15 and the second tab unit 40 can be effectively reduced, thereby improving production efficiency. In addition, by bonding and connecting the first end 531 and the third end 541, and bonding and connecting the second end 532 and the fourth end 542, the bonding strength of the first protective layer 53 and the second protective layer 54 can be enhanced, thereby reducing the probability that the insulating component 50 is broken in the circumferential direction and exposes the first tab unit 30, the second tab unit 40 and the first protrusion 15.

[0041] In some embodiments, see Figure 3 , observing the pole piece 100 along the second direction Y, the first protective layer 53 and the second protective layer 54 of the insulating component 50 are an integral structure, and the insulating component 50 is wound clockwise or counterclockwise with the second direction Y as the winding axis and arranged on the circumferential periphery of the first pole lug unit 30, the first protrusion 15 and the second pole lug unit 40. The insulating component 50 can be wound in the above-mentioned winding manner so that the first protective layer 53 can stably and firmly wrap the first pole lug unit 30, the first protrusion 15 and the second pole lug unit 40 in a high temperature environment, thereby preventing the first pole lug unit 30, the first protrusion 15 and the second pole lug unit 40 from being exposed. It is worth noting that after being wound clockwise or counterclockwise, the insulating component 50 should be connected end to end or fused end to end or fixedly connected end to end by at least partial overlap, so as to avoid the insulating component 50 from breaking in a high temperature environment and causing the first pole lug unit 30, the first protrusion 15 and the second pole lug unit 40 to be exposed. Of course, in addition to being wound clockwise or counterclockwise, the insulating component 50 can also be arranged with its middle portion on one side of the first tab unit 30, the first protrusion 15 and the second tab unit 40, and then the two ends of the insulating component 50 are folded in half and bonded together.

[0042] In some embodiments, see Figure 4, along the first direction X, the thickness H1 of the first protective layer 53 satisfies: 10um≤H1≤50um; and / or, along the first direction X, the thickness H2 of the second protective layer 54 satisfies: 10um≤H2≤50um. If the thickness of the first protective layer 53 and the second protective layer 54 is too thin, it is easy to be punctured by the tip or burr of the first weld mark 30a and the second weld mark 40a, resulting in insulation failure; if the thickness of the first protective layer 53 and the second protective layer 54 is too thick, it will cause the thickness of the pole piece 100 in the area wrapped with the insulating component 50 to be too thick, thereby reducing the energy density of the electrochemical device. Further, along the first direction X, the thickness H1 of the first protective layer 53 satisfies: 15um≤H1≤25um; and / or, along the first direction X, the thickness H2 of the second protective layer 54 satisfies: 15um≤H2≤25um. By setting the thickness of the first protective layer 53 and the thickness of the second protective layer 54 within the above range, the thickness of the insulating component 50 can be reduced as much as possible while meeting the insulation requirements, thereby reducing the occupied space and improving the energy density of the electrochemical device.

[0043] In some embodiments, the insulating component 50 includes at least one of polyethylene terephthalate, polypropylene, and polyimide. The insulating component 50 is made of the above materials. On the one hand, the insulating component 50 can have good insulation properties, thereby avoiding insulation failure of the first tab unit 30 and the second insulating unit 40 at the first weld mark 30a and the second weld mark 40a. In addition, the above materials have good heat resistance. In a high temperature environment, the insulating component 50 is not easy to shrink and the shrinkage is small, thereby ensuring that the insulating component 50 can effectively cover the first tab unit 30 and the second tab unit 40; on the other hand, the thickness of the insulating component 50 can be made relatively thin, for example, the insulating component 50 can be an insulating adhesive tape, thereby greatly reducing the thickness of the insulating component 50. The first protective layer 53 and the second protective layer 54 can be single-sided adhesive with stickiness on one side, and the sticky surfaces are arranged facing each other, so that the first end 531 is bonded and connected to the third end 541, and the second end 532 is bonded and connected to the fourth end 542.

[0044] The present application further provides an electrode assembly embodiment, the electrode assembly comprising a diaphragm and the pole piece 100 in any of the above embodiments. The specific structure and function of the pole piece 100 can be referred to the above embodiments, and will not be described in detail here.

[0045] The present application also provides an embodiment of an electrochemical device, which includes an electrode assembly. The specific structure and function of the electrode sheet 100 in the electrode assembly can be found in the above embodiments, and will not be described in detail here.

[0046] The pole piece 100 of the embodiment of the present application includes a current collector 10, an active material layer 20, a first pole lug unit 30, a second pole lug unit 40 and an insulating component 50. The current collector 10 includes a support layer 11, and a first conductive layer 12 and a second conductive layer 13 arranged on both sides of the support layer 11 along a first direction X, the first direction X is the thickness direction of the current collector 10, the current collector 10 includes a first main body 14 and a first convex portion 15 connected along a second direction Y, along a third direction Z, the width of the first convex portion 15 is less than the width of the first main body 14, and the first direction X, the second direction Y and the third direction Z are perpendicular to each other; the active material layer 20 is arranged on the first main body 14, and in the first direction X, at least one of the surface of the first conductive layer 12 away from the support layer 11 and the surface of the second conductive layer 13 away from the support layer 11 is provided with the active material layer 20; the first The pole lug unit 30 extends along the second direction Y, and a portion of the first pole lug unit 30 is welded to the first conductive layer 12 on the first protrusion 15, and the first pole lug unit 30 and the first conductive layer 12 form a first weld mark 30a; the second pole lug unit 40 extends along the second direction Y, and a portion of the second pole lug unit 40 is welded to the second conductive layer 13 on the first protrusion 15, and the second pole lug unit 40 and the second conductive layer 13 form a second weld mark 40a; the insulating component 50 is arranged on the first protrusion 15, and the insulating component 50 covers the first weld mark 30a and the second weld mark 40a at the same time. Along the third direction Z, the width of the insulating component 50 is greater than the width of the first pole lug unit 30 and the second pole lug unit 40. The pole piece 100 of the present application sets the width of the insulating component 50 to be greater than the width of the first pole lug unit 30 and the width of the second pole lug unit 40, that is, both ends of the insulating component 50 in the third direction Z extend beyond the first pole lug unit 30 and the second pole lug unit 40. In this way, in a high-temperature environment, the insulating component 50 can effectively wrap the first pole lug unit 30 and the second pole lug unit 40 even if it shrinks, thereby preventing the insulating component 50 from shrinking and exposing the first pole lug unit 30 and the second pole lug unit 40, thereby improving the safety performance of the electrochemical device.

[0047] The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A pole piece, It is characterized in that include: A current collector, comprising a support layer, and a first conductive layer and a second conductive layer arranged on both sides of the support layer along a first direction, wherein the first direction is a thickness direction of the current collector, the current collector comprises a first main body portion and a first convex portion connected to each other along a second direction, and along a third direction, a width of the first convex portion is smaller than a width of the first main body portion, and the first direction, the second direction and the third direction are perpendicular to each other; an active material layer, disposed on the first main body, and in the first direction, the active material layer is disposed on at least one of a surface of the first conductive layer facing away from the support layer and a surface of the second conductive layer facing away from the support layer; A first tab unit extends along the second direction, a portion of the first tab unit is welded to the first conductive layer on the first protrusion, and a first welding mark is formed between the first tab unit and the first conductive layer; A second tab unit extending along the second direction, wherein a portion of the second tab unit is welded to the second conductive layer on the first protrusion, and a second welding mark is formed between the second tab unit and the second conductive layer; An insulating component is arranged on the first protrusion, and the insulating component covers the first weld mark and the second weld mark at the same time. Along the third direction, the width of the insulating component is greater than the width of the first pole lug unit and the width of the insulating component is greater than the width of the second pole lug unit.

2. The pole piece according to claim 1, It is characterized in that The insulating component comprises a first protective layer and a second protective layer, the first protective layer is arranged on a surface of the first tab unit away from the first conductive layer and covers the first weld mark, and along the third direction, the first protective layer has a first end and a second end opposite to each other; The second protective layer is arranged on the surface of the second pole ear unit facing away from the second conductive layer and covers the second weld mark. Along the third direction, the second protective layer has a third end and a fourth end relative to each other; the first end is connected to the third end, and the second end is connected to the fourth end.

3. The pole piece according to claim 2, It is characterized in that The first protective layer and the second protective layer are an integrated structure, and the second direction is used as a winding axis. The insulating component is wound around the first tab unit, the second tab unit, and the first protrusion.

4. The pole piece according to claim 2, It is characterized in that Along the first direction, the thickness H1 of the first protective layer satisfies: 10um≤H1≤50um; and / or, along the first direction, the thickness H2 of the second protective layer satisfies: 10um≤H2≤50um.

5. The pole piece according to claim 4, It is characterized in that 15um≤H1≤25um; and / or, 15um≤H2≤25um.

6. The pole piece according to claim 1, It is characterized in that Observing along the first direction, in the third direction, the width of the first pole tab unit is equal to the width of the first protrusion, and / or in the third direction, the width of the second pole tab unit is equal to the width of the first protrusion.

7. The pole piece according to claim 1, It is characterized in that When viewed along the first direction, in the third direction, the width K1 of the first pole lug unit satisfies: 5 mm ≤ K1 ≤ 20 mm; in the second direction, the length L1 of the first pole lug unit satisfies: 5 mm ≤ L1 ≤ 20 mm; and / or, Observed along the first direction, in the third direction, the width K2 of the second pole lug unit satisfies: 5 mm ≤ K2 ≤ 20 mm; in the second direction, the length L2 of the second pole lug unit satisfies: 5 mm ≤ L2 ≤ 20 mm.

8. The pole piece according to claim 7, It is characterized in that 7mm≤K1≤9mm, 9mm≤L1≤11mm; and / or, 7mm≤K2≤9mm, 9mm≤L2≤11mm.

9. The pole piece according to claim 1, It is characterized in that Observed along the first direction, in the third direction, the first pole lug unit has a first side and a second side, the insulating component has a third side and a fourth side, wherein the first side and the third side are located on the same side of the first pole lug unit, and the second side and the fourth side are located on the other same side of the first pole lug unit; Along the third direction, a distance L3 between the first side and the third side satisfies: 0.5 mm ≤ L3 ≤ 2 mm; and / or, Along the third direction, a distance L4 between the second side and the fourth side satisfies: 0.5 mm ≤ L4 ≤ 2 mm.

10. The pole piece according to claim 9, It is characterized in that 0.8mm≤L3≤1.2mm; and / or, 0.8mm≤L4≤1.2mm.

11. The pole piece according to claim 1, It is characterized in that The insulating component includes at least one of polyethylene terephthalate, polypropylene, and polyimide.

12. An electrode assembly, It is characterized in that Comprising a pole piece as described in any one of claims 1-11.

13. An electrochemical device, It is characterized in that Comprising the electrode assembly as claimed in claim 12.

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