Electrode assembly, electrochemical device, and electric equipment

Abstract

Embodiments of the present application provide an electrode assembly, an electrochemical device and an electric equipment. The electrode assembly comprises a first pole piece and a second pole piece with opposite polarities. The first current collector comprises a first conductive layer, a first insulating layer and a second conductive layer arranged in sequence along the thickness direction of the first current collector. The first active material layer is provided with a first groove, the first surface of the first single-sided empty foil area is exposed to the first groove, and the second surface of the first single-sided empty foil area is covered by the second active material layer. The second active material layer is provided with a second groove, the first surface of the second single-sided empty foil area is covered by the first active material layer, and the second surface of the second single-sided empty foil area is exposed to the second groove. The first lug is at least partially accommodated in the first groove and is bonded to the first single-sided empty foil area through a first bonding layer. The second lug is at least partially accommodated in the second groove and is bonded to the second single-sided empty foil area through a second bonding layer, which can effectively reduce the safety risk of the traditional composite current collector.

Description

Technical Field

[0001] This application relates to the field of electrochemical device technology, and more specifically, to an electrode assembly, an electrochemical device, and an electrical device. Background Technology

[0002] With the development of electronic information technology, various electronic devices are also developing towards intelligence and multi-functionality, which places increasingly higher demands on the energy density of electrochemical devices.

[0003] Existing composite current collectors have a three-layer structure: an insulating layer in the middle and conductive layers on both sides. Because the insulating layer in the middle cannot be directly welded to the electrode tab, it needs to be welded to the electrode tab via the conductive layers. The high-temperature melting of the insulating layer during welding enables conductivity between the conductive layers on both sides. However, the conductive layer of the composite current collector is relatively thin, making it prone to over-welding and cracking at the weld joint, leading to safety risks. Furthermore, the insulating layer may not melt sufficiently during the melting process, resulting in a lack of electrical contact between the conductive layers on both sides and weakening the current-carrying capacity of the electrode. Summary of the Invention

[0004] This application provides an electrode assembly, an electrochemical device, and an electrical device that can solve at least one of the above-mentioned technical problems.

[0005] This application is achieved through the following technical solution:

[0006] In a first aspect, this application provides an electrode assembly including a first electrode and a second electrode with opposite polarities. The first electrode includes a first current collector, a first active material layer, a second active material layer, a first tab, and a second tab. The first current collector includes a first conductive layer, a first insulating layer, and a second conductive layer sequentially distributed along its thickness direction. The first conductive layer has a first surface facing away from the first insulating layer, and the second conductive layer has a second surface facing away from the first insulating layer. The first active material layer is disposed on the first surface, and the second active material layer is disposed on the second surface. The first current collector includes a first single-sided empty foil area and a second single-sided empty foil area; a first active material layer is provided with a first groove, the first surface of the first single-sided empty foil area is exposed in the first groove, and the second surface of the first single-sided empty foil area is covered by a second active material layer; a second active material layer is provided with a second groove, the first surface of the second single-sided empty foil area is covered by the first active material layer, and the second surface of the second single-sided empty foil area is exposed in the second groove; a first electrode tab is at least partially accommodated in the first groove and is bonded to the first single-sided empty foil area through a first adhesive layer, and the first electrode tab is electrically connected to the first conductive layer; a second electrode tab is at least partially accommodated in the second groove and is bonded to the second single-sided empty foil area through a second adhesive layer, and the second electrode tab is electrically connected to the second conductive layer.

[0007] In the above scheme, the first electrode and the second electrode have opposite polarities, which allows metal ions to move between the first electrode and the second electrode, thereby realizing the charging and discharging of the electrode assembly; the first current collector includes a first conductive layer, a first insulating layer and a second conductive layer distributed sequentially along its thickness direction, a first active material layer is disposed on the first surface of the first conductive layer and a second active material layer is disposed on the second surface of the second conductive layer, which allows metal ions to be inserted into or extracted from the first active material layer and the second active material layer, thereby realizing the movement of metal ions. The first current collector includes a first single-sided empty foil area and a second single-sided empty foil area. The first surface of the first single-sided empty foil area is bonded to the first electrode tab, and the second surface of the first single-sided empty foil area is covered by a second active material layer. The first surface of the second single-sided empty foil area is covered by the first active material layer, and the second surface of the second single-sided empty foil area is bonded to the second electrode tab. Compared to the case where grooves are provided on both the side of the current collector connected to the electrode tab and the side away from the electrode tab, in this application, the first current collector has a second active material layer on the side away from the first electrode tab and a first active material layer on the side away from the second electrode tab. This reduces the loss of active material, resulting in the electrode assembly having more active material layers, which facilitates improving the energy density of the electrochemical device constituted by the electrode assembly. At the same time, the first current collector is a composite current collector, with the first electrode tab and the second electrode tab distributed on both sides of the first current collector. The first electrode tab is electrically connected to the first conductive layer, and the second electrode tab is electrically connected to the second conductive layer, which facilitates the output or input of electrical energy. The provision of the first electrode tab and the second electrode tab increases the number of electrodes and can also improve the charge and discharge rate. The first electrode tab is at least partially housed within the first groove, and the second electrode tab is at least partially housed within the second groove. This facilitates the connection between the first electrode tab and the first current collector, as well as the connection between the second electrode tab and the first current collector. It also allows for a smaller overall thickness of the electrode assembly, resulting in a higher energy density in the electrochemical device equipped with this electrode assembly. The first electrode tab is bonded to the first conductive layer via a first adhesive layer, and the second electrode tab is bonded to the second conductive layer via a second adhesive layer. This simplifies operation and reduces manufacturing difficulty. Furthermore, by bonding the first electrode tab to the first conductive layer via the first adhesive layer and the second electrode tab to the second conductive layer via the second adhesive layer, welding the electrode tabs is eliminated, reducing the safety risk to the first current collector caused by solder joint cracking.

[0008] In one or more of the above optional embodiments, the electrode assembly is a wound structure; along the winding direction of the electrode assembly, the width of the first groove is W1, and along the winding axis direction of the electrode assembly, the length of the first groove is L1, satisfying 5mm≤W1≤15mm, 5mm≤L1≤25mm; and / or, along the winding direction of the electrode assembly, the width of the second groove is W2, and along the winding axis direction of the electrode assembly, the length of the second groove is L2, satisfying 5mm≤W2≤15mm, 5mm≤L2≤25mm.

[0009] In the above scheme, by ensuring that the width W1 of the first groove along the winding direction of the electrode assembly satisfies 5mm≤W1≤15mm, and the length L1 of the first groove along the winding axis of the electrode assembly satisfies 5mm≤L1≤25mm, on the one hand, the first current collector and the first electrode tab have a larger connection area, and the first current collector and the first electrode tab have a larger flow capacity; on the other hand, the volume loss of the first active material layer is smaller, and the energy density of the electrochemical device with this electrode assembly is higher. Similarly, by ensuring that the width W2 of the second groove along the winding direction of the electrode assembly satisfies 5mm≤W2≤15mm, and the length L2 of the second groove along the winding axis of the electrode assembly satisfies 5mm≤L2≤25mm, on the one hand, the first current collector and the second electrode tab have a larger connection area, and the first current collector and the second electrode tab have a larger flow capacity; on the other hand, the volume loss of the second active material layer is smaller, and the energy density of the electrochemical device with this electrode assembly is higher.

[0010] In one or more of the above optional embodiments, the electrode assembly is a wound structure; the first tab includes a first portion overlapping the first current collector, the thickness of the first portion is H1, the width of the first portion along the winding direction of the electrode assembly is W3, and the length of the first portion along the winding axis of the electrode assembly is L3, satisfying 2mm≤W3≤14mm, 2mm≤L3≤24mm, 20μm≤H1≤120μm; and / or, the second tab includes a second portion overlapping the first current collector, the thickness of the second portion is H2, the width of the second portion along the winding direction of the electrode assembly is W4, and the length of the second portion along the winding axis of the electrode assembly is L4, satisfying 2mm≤W4≤14mm, 2mm≤L4≤24mm, 20μm≤H2≤120μm.

[0011] In the above scheme, by ensuring that the thickness H1 of the first part satisfies 20μm≤H1≤120μm; the width W3 of the first part satisfies 2mm≤W3≤14mm along the winding direction of the electrode assembly; and the length L3 of the first part satisfies 2mm≤L3≤24mm along the winding axis of the electrode assembly, on the one hand, the first electrode tab and the first current collector have a large connection area, and the first electrode tab and the first fluid have a large flow capacity; on the other hand, the area of ​​the first groove can be smaller, the volume loss of the first active material layer can be smaller, and the energy density of the electrochemical device with this electrode assembly is higher. By ensuring that the thickness H2 of the second part satisfies 20μm≤H2≤120μm; the width W4 of the second part satisfies 2mm≤W4≤14mm along the winding direction of the electrode assembly; and the length L4 of the second part satisfies 2mm≤L4≤24mm along the winding axis of the electrode assembly, on the one hand, the second electrode tab and the first current collector have a larger connection area, and the second electrode tab and the first fluid have a larger flow capacity; on the other hand, the area of ​​the second groove can be smaller, the volume loss of the second active material layer can be smaller, and the energy density of the electrochemical device equipped with this electrode assembly is higher.

[0012] In one or more of the above optional embodiments, the electrode assembly is a wound structure; the first electrode has a winding start end and a winding end, and along the winding direction of the electrode assembly, the first groove is closer to the winding start end than the second groove; along the winding direction of the electrode assembly, the distance between the first groove and the winding start end is M1, the distance between the second groove and the winding end end is M2, and the length of the first electrode is M3, satisfying that 0.25≤M1 / M3≤0.35; 0.25≤M2 / M3≤0.35.

[0013] In the above scheme, by making the distance between the first groove and the winding start end M1 along the winding direction of the electrode assembly, the distance between the second groove and the winding end M2, and the length of the first electrode M3, with 0.25≤M1 / M3≤0.35 and 0.25≤M2 / M3≤0.35, on the one hand, it facilitates processing and manufacturing, and reduces the risk of interference between the first groove and the second groove; on the other hand, it facilitates the flow of current between the first current collector and the first and second electrodes, facilitates the output and input of electrical energy, and helps to improve charging and discharging efficiency.

[0014] In one or more of the above optional embodiments, a plurality of first protrusions are formed on the side of the first electrode facing the first current collector, and at least a portion of the plurality of first protrusions is in contact with the first conductive layer.

[0015] In the above scheme, the arrangement of multiple first protrusions facilitates the positioning of the first electrode tab on the first adhesive layer. The first adhesive layer can be accommodated in the area between two adjacent first protrusions, increasing the bonding effect between the first electrode tab and the first conductive layer. At least a portion of the multiple first protrusions contacts the first conductive layer to achieve electrical connection between the first electrode tab and the first conductive layer.

[0016] In one or more of the above optional embodiments, the first electrode further includes a first insulating member and a second insulating member. The first insulating member is disposed on the side of the first electrode tab away from the first current collector and covers the first electrode tab. The second insulating member is disposed on the side of the second electrode tab away from the first current collector and covers the second electrode tab.

[0017] In the above scheme, the first insulating element covers the first tab, enabling it to insulate the first tab from the second electrode, reducing the possibility of a short circuit between the first and second electrodes. Similarly, the second insulating element covers the second tab, insulating it from the second electrode, reducing the possibility of a short circuit between the first and second electrodes. Because the surfaces of the first and second tabs have burrs, the first and second insulating elements also isolate these burrs, making it difficult for them to come into contact with the second electrode and cause a short circuit or damage.

[0018] In one or more of the above optional embodiments, the second electrode includes a second current collector, a third active material layer, a fourth active material layer, and a third tab. The second current collector has a third surface and a fourth surface disposed opposite to each other, and the second current collector includes a third single-sided empty foil area. The third active material layer is disposed on the third surface and has a third groove. The third surface of the third single-sided empty foil area is exposed in the third groove. The fourth active material layer is disposed on the fourth surface and is covered by the fourth active material layer. The third tab is at least partially accommodated in the third groove and is bonded to the third single-sided empty foil area through a third adhesive layer. The third tab is electrically connected to the second current collector.

[0019] In the above scheme, a third active material layer is disposed on a third surface, and a fourth active material layer is disposed on a fourth surface, allowing metal ions to be inserted into or extracted from the third and fourth active material layers to achieve metal ion movement. The second current collector includes a third single-sided empty foil region. The third surface of the third single-sided empty foil region is bonded to a third tab, and the fourth surface of the third single-sided empty foil region is covered by a fourth active material layer. Compared to cases where grooves are provided on both the side of the current collector connected to the tab and the side away from the tab, in this application, the second current collector has a fourth active material layer on the side away from the third tab, reducing the loss of active material and resulting in an electrode assembly with more active material layers, which facilitates improving the energy density of the electrochemical device constructed from this electrode assembly. The third tab is at least partially accommodated within a third groove, facilitating the connection between the third tab and the second current collector and also reducing the overall thickness of the electrode assembly, resulting in a higher energy density for the electrochemical device equipped with this electrode assembly. The third tab and the third single-sided empty foil region are bonded by a third adhesive layer, facilitating operation and reducing manufacturing difficulty.

[0020] In one or more of the above optional embodiments, the second current collector includes a third conductive layer, a second insulating layer, and a fourth conductive layer sequentially distributed along its thickness direction. The third surface is the surface of the third conductive layer facing away from the second insulating layer, and the fourth surface is the surface of the fourth conductive layer facing away from the second insulating layer. The second current collector also includes a fourth single-sided empty foil region. The fourth active material layer is provided with a fourth groove. The third surface of the fourth single-sided empty foil region is covered by the third active material layer, and the fourth surface of the fourth single-sided empty foil region is exposed in the fourth groove. The second electrode also includes a fourth electrode tab. The fourth electrode tab is at least partially accommodated in the fourth groove and is bonded to the fourth single-sided empty foil region through a fourth adhesive layer. The third electrode tab is electrically connected to the third conductive layer, and the fourth electrode tab is electrically connected to the fourth conductive layer.

[0021] In the above scheme, the second current collector is a composite current collector, and the third and fourth tabs are distributed on both sides of the first current collector. The third tab is electrically connected to the third conductive layer, and the fourth tab is electrically connected to the fourth conductive layer to facilitate the conduction or introduction of electrical energy. The addition of the third and fourth tabs increases the number of tabs and also improves the charge and discharge rate. The fourth tab is at least partially housed in the fourth groove, which facilitates the connection between the fourth tab and the second current collector and also allows for a smaller overall thickness of the electrode assembly, resulting in a higher energy density in the electrochemical device equipped with this electrode assembly. The fourth tab is bonded to the fourth single-sided empty foil area through the fourth adhesive layer, which facilitates operation and reduces manufacturing difficulty.

[0022] In one or more of the above optional embodiments, the second electrode further includes a third insulating member disposed on the side of the third electrode tab away from the second current collector and covering the third electrode tab.

[0023] In the above scheme, the third insulating element covers the third tab, enabling it to insulate the third tab from the first electrode, thus reducing the possibility of a short circuit between the second and first electrodes. Because the surface of the third tab has burrs, the third insulating element also isolates these burrs, making it less likely for them to come into contact with the first electrode and cause a short circuit or damage.

[0024] In one or more of the above optional embodiments, the first electrode further includes a fourth insulating member disposed on the first active material layer. When viewed along the thickness direction of the first current collector, the projection of the fourth insulating member covers the third electrode tab.

[0025] In the above scheme, by making the projection of the fourth insulating element cover the third electrode when viewed along the thickness direction of the first current collector, the fourth insulating element can isolate the burrs of the third electrode, making it difficult for the burrs to come into contact with the first active material layer and cause a short circuit or damage to the first electrode.

[0026] In one or more of the above optional embodiments, the second electrode further includes a fifth insulating member and a sixth insulating member. The fifth insulating member is disposed on the third active material layer, and when viewed along the thickness direction of the second current collector, the projection of the fifth insulating member covers the first electrode tab. The sixth insulating member is disposed on the fourth active material layer, and when viewed along the thickness direction of the second current collector, the projection of the sixth insulating member covers the second electrode tab.

[0027] In the above scheme, by ensuring that the projection of the fifth insulating member covers the first electrode tab when viewed along the thickness direction of the second current collector, the fifth insulating member can isolate the burrs of the first electrode tab, further making it less likely for the burrs to contact the second active material layer and cause a short circuit or damage to the second electrode. By ensuring that the projection of the sixth insulating member covers the second electrode tab when viewed along the thickness direction of the second current collector, the sixth insulating member can isolate the burrs of the second electrode tab, further making it less likely for the burrs to contact the second active material layer and cause a short circuit or damage to the second electrode.

[0028] In one or more of the above optional embodiments, the electrode assembly is a wound structure; along the winding direction of the electrode assembly, the width of the third groove is W5, and along the winding axis direction of the electrode assembly, the length of the third groove is L5, satisfying 5mm≤W5≤15mm, 5mm≤L5≤25mm; and / or, the third tab includes a third part connected to the third single-sided empty foil area, the thickness of the third part is H3, along the winding direction of the electrode assembly, the width of the third part is W6, and along the winding axis direction of the electrode assembly, the length of the third part is L6, satisfying 2mm≤W6≤14mm, 2mm≤L6≤24mm, 20μm≤H3≤120μm.

[0029] In the above scheme, by ensuring that the width W5 of the third groove along the winding direction of the electrode assembly satisfies 5mm≤W5≤15mm, and the length L5 of the third groove along the winding axis of the electrode assembly satisfies 5mm≤L5≤25mm, on the one hand, the second current collector and the third electrode tab have a larger connection area, and the second current collector and the third electrode tab have a larger flow capacity; on the other hand, the volume loss of the third active material layer can be reduced, and the energy density of the electrochemical device with this electrode assembly is higher. By ensuring that the thickness H3 of the third part satisfies 20μm≤H3≤120μm; the width W6 of the third part satisfies 2mm≤W6≤14mm along the winding direction of the electrode assembly; and the length L6 of the third part satisfies 2mm≤L6≤24mm along the winding axis of the electrode assembly, on the one hand, the third tab and the second current collector have a larger connection area, and the third tab and the second current collector have a larger flow capacity; on the other hand, the area of ​​the third groove can be smaller, the volume loss of the third active material layer can be smaller, and the energy density of the electrochemical device equipped with this electrode assembly is higher.

[0030] In one or more of the above optional embodiments, at least one of the first adhesive layer, the second adhesive layer, the third adhesive layer, and the fourth adhesive layer is a conductive adhesive.

[0031] In the above scheme, at least one of the first adhesive layer, the second adhesive layer, the third adhesive layer, and the fourth adhesive layer is a conductive adhesive, which can better realize the electrical connection between the electrode and the current collector and increase the conductivity.

[0032] In one or more of the above optional embodiments, the thickness of the first conductive layer, the second conductive layer, the third conductive layer, and the fourth conductive layer is 0.2 μm to 3 μm.

[0033] In the above scheme, the thickness of the conductive layer is greater than 0.2μm, which enables the conductive layer to have good conductivity. The thickness is less than 3μm, which ensures that the energy density of the battery will not be lost too much. Furthermore, since the middle of the composite current collector is an insulating layer, the conductive layer needs to be set on the insulating layer by vapor deposition, so the thickness cannot be too thick.

[0034] In one or more of the above optional embodiments, the first electrode is a positive electrode and the second electrode is a negative electrode.

[0035] In the above scheme, the first electrode is a positive electrode, and the first and second tabs are positive tabs. Compared with a single positive tab, the two positive tabs structure of this application can reduce the internal resistance of the electrochemical device, increase the charging and discharging speed, and reduce the charging temperature rise.

[0036] Secondly, this application also provides an electrochemical device including an electrode assembly provided according to any of the above embodiments.

[0037] Thirdly, this application also provides an electrical device, including an electrochemical device according to the above embodiments, the electrochemical device being used to provide electrical energy.

[0038] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 Cross-sectional views of electrode assemblies provided in some embodiments of this application;

[0041] Figure 2 This is a schematic diagram of the structure of the first electrode provided in some embodiments of this application;

[0042] Figure 3 This is a schematic diagram of the assembly of a plurality of first protrusions and a first conductive layer provided in some embodiments of this application;

[0043] Figure 4 Cross-sectional views of electrode assemblies provided for other embodiments of this application;

[0044] Figure 5 A cross-sectional view of an electrode assembly provided for some embodiments of this application;

[0045] Figure 6 This is a schematic diagram of the structure of the second electrode provided in some embodiments of this application;

[0046] Figure 7 A cross-sectional view of an electrode assembly provided in some embodiments of this application.

[0047] Icons: 1-Electrode assembly; 10-First electrode; 11-First current collector; 111-First conductive layer; 112-First insulating layer; 113-Second conductive layer; 114-First surface; 115-Second surface; 116-First single-sided empty foil area; 117-Second single-sided empty foil area; 12-First active material layer; 121-First groove; 13-Second active material layer; 131-Second groove; 14-First tab; 141-First portion; 142-First protrusion; 15-Second tab; 151-Second portion; 161-First adhesive layer; 162-Second adhesive layer; 171-First insulating element; 172-Second insulating element; 173-Fourth insulating element; 181-Roll 182 - Starting end; 20 - Second electrode; 21 - Second current collector; 211 - Third surface; 212 - Fourth surface; 213 - Third single-sided empty foil area; 214 - Third conductive layer; 215 - Second insulating layer; 216 - Fourth conductive layer; 217 - Fourth single-sided empty foil area; 22 - Third active material layer; 221 - Third groove; 23 - Fourth active material layer; 231 - Fourth groove; 24 - Third electrode tab; 241 - Third part; 25 - Fourth electrode tab; 251 - Fourth part; 261 - Third adhesive layer; 262 - Fourth adhesive layer; 271 - Third insulating element; 272 - Fifth insulating element; 273 - Sixth insulating element; 274 - Seventh insulating element. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0049] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0050] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0051] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0052] In this application, the term "and / or" 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, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0053] In this application, "multiple" refers to two or more (including two), and similarly, "multiple groups" refers to two or more (including two), and "multiple pieces" refers to two or more (including two).

[0054] An electrochemical device includes a housing, electrode components, and an electrolyte. The housing contains the electrode components and the electrolyte. The housing can be made of aluminum, aluminum-plastic film, etc. The electrode components consist of a positive electrode, a negative electrode, and a separator. The electrochemical device primarily operates by the movement of metal ions between the positive and negative electrode components. 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. The portion of the positive current collector without the positive active material layer has a positive electrode tab, through which electrical energy is input or output. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary materials, or lithium manganese oxide, etc. 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. The portion of the negative current collector without the negative active material layer has a negative electrode tab, through which electrical energy is input or output. The negative electrode current collector can be made of copper, and the negative electrode active material can be made of carbon or silicon, etc. The separator can be made of polypropylene or polyethylene, etc. The separator is placed between the positive and negative electrode plates to isolate them, but allows metal ions to pass through.

[0055] With the development of the new energy industry, electrochemical devices are moving towards higher energy density and higher power density. However, current electrode assemblies typically consist of a current collector, two layers of active material disposed on opposite sides of the current collector, and a tab. Grooves are required on the active material layer to accommodate the tab, allowing it to connect to the current collector. However, due to process limitations, when welding the tab to the current collector, two opposing grooves need to be formed simultaneously on the two active material layers, with the tab only fitting into one of them. This results in wasted grooves on the side of the current collector away from the tab, leading to loss of active material and lower energy density in the electrochemical device. Furthermore, existing composite current collectors have a three-layer structure: an insulating layer in the middle and conductive layers on both sides. Because the insulating layer in the middle of the composite current collector cannot be directly welded to the tab, it needs to be welded to the tab via the conductive layer. The high-temperature melting of the insulating layer during welding enables conduction between the conductive layers on both sides. However, the conductive layer of the composite current collector is relatively thin, making it prone to over-welding and cracking at the weld joint, posing a safety risk. Furthermore, the insulation layer also suffers from insufficient melting during the melting process, resulting in a lack of electrical contact between the conductive layers on both sides, which weakens the current-carrying capacity of the electrode.

[0056] To improve the safety performance of electrochemical devices, this application provides an electrode assembly including a first electrode and a second electrode with opposite polarities. The first electrode includes a first current collector, a first active material layer, a second active material layer, a first tab, and a second tab. The first current collector includes a first conductive layer, a first insulating layer, and a second conductive layer sequentially distributed along its thickness direction. The first conductive layer has a first surface facing away from the first insulating layer, and the second conductive layer has a second surface facing away from the first insulating layer. The first active material layer is disposed on the first surface, and the second active material layer is disposed on the second surface. The first current collector includes a first single-sided empty foil area and a second single-sided empty foil area. A first active material layer has a first groove, with the first surface of the first single-sided empty foil area exposed in the first groove and the second surface of the first single-sided empty foil area covered by a second active material layer. A second active material layer has a second groove, with the first surface of the second single-sided empty foil area covered by the first active material layer and the second surface of the second single-sided empty foil area exposed in the second groove. A first electrode tab is at least partially accommodated in the first groove and bonded to the first single-sided empty foil area via a first adhesive layer. A second electrode tab is at least partially accommodated in the second groove and bonded to the second single-sided empty foil area via a second adhesive layer. By bonding the first electrode tab to the first conductive layer via the first adhesive layer and the second electrode tab to the second conductive layer via the second adhesive layer, soldering of the electrode tabs is eliminated, reducing the safety risk of the first current collector due to solder cracking. In this electrode assembly, the first electrode and the second electrode have opposite polarities, allowing metal ions to move between the first electrode and the second electrode, thereby enabling the charging and discharging of the electrode assembly. The first current collector includes a first conductive layer, a first insulating layer, and a second conductive layer distributed sequentially along its thickness direction. A first active material layer is disposed on the first surface of the first conductive layer, and a second active material layer is disposed on the second surface of the second conductive layer, allowing metal ions to be inserted into or extracted from the first active material layer and the second active material layer, thereby enabling the movement of metal ions.The first current collector includes a first single-sided empty foil area and a second single-sided empty foil area. The first surface of the first single-sided empty foil area is bonded to the first electrode tab, and the second surface of the first single-sided empty foil area is covered by a second active material layer. The first surface of the second single-sided empty foil area is covered by the first active material layer, and the second surface of the second single-sided empty foil area is bonded to the second electrode tab. Compared to the case where grooves are provided on both the side of the current collector connected to the electrode tab and the side away from the electrode tab, in this application, the first current collector has a second active material layer on the side away from the first electrode tab and a first active material layer on the side away from the second electrode tab. This reduces the loss of active material, resulting in the electrode assembly having more active material layers, which facilitates improving the energy density of the electrochemical device constituted by the electrode assembly. At the same time, the first current collector is a composite current collector, with the first electrode tab and the second electrode tab distributed on both sides of the first current collector. The first electrode tab is electrically connected to the first conductive layer, and the second electrode tab is electrically connected to the second conductive layer, which facilitates the output or input of electrical energy. The provision of the first electrode tab and the second electrode tab increases the number of electrodes and can also improve the charge and discharge rate. The first electrode tab is at least partially housed within the first groove, and the second electrode tab is at least partially housed within the second groove. This facilitates the connection between the first electrode tab and the first current collector, as well as the connection between the second electrode tab and the first current collector. It also allows for a smaller overall thickness of the electrode assembly, resulting in a higher energy density in the electrochemical device equipped with this electrode assembly. The first electrode tab is bonded to the first conductive layer via a first adhesive layer, and the second electrode tab is bonded to the second conductive layer via a second adhesive layer. This simplifies operation and reduces manufacturing difficulty. Furthermore, by bonding the first electrode tab to the first conductive layer via the first adhesive layer and the second electrode tab to the second conductive layer via the second adhesive layer, welding the electrode tabs is eliminated, reducing the safety risk to the first current collector caused by solder joint cracking.

[0057] This application provides an electrochemical device including an electrode assembly. The electrochemical device can be a secondary battery or a primary battery, such as a lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, etc., and this application is not limited to this. The electrochemical device can be cylindrical, flat, cuboid, or other shapes.

[0058] This application provides an electrical device that uses an electrochemical device as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc.

[0059] Please refer to Figure 1 , Figure 1 This is a cross-sectional view of an electrode assembly provided in some embodiments of this application. Figure 1 This is a cross-sectional view of the electrode assembly in its unfolded state.

[0060] This application provides an electrode assembly 1, which includes a first electrode 10 and a second electrode 20 with opposite polarities. The first electrode 10 includes a first current collector 11, a first active material layer 12, a second active material layer 13, a first tab 14, and a second tab 15. The first current collector 11 includes a first conductive layer 111, a first insulating layer 112, and a second conductive layer 113 sequentially distributed along its thickness direction. The first conductive layer 111 has a first surface 114 facing away from the first insulating layer 112, and the second conductive layer 113 has a second surface 115 facing away from the first insulating layer 112. The first active material layer 12 is disposed on the first surface 114, and the second active material layer 13 is disposed on the second surface 115. The first current collector 11 includes a first single-sided empty foil area 116 and a second single-sided empty foil area 117; the first active material layer 12 is provided with a first groove 121, the first surface 114 of the first single-sided empty foil area 116 is exposed in the first groove 121, and the second surface 115 of the first single-sided empty foil area 116 is covered by the second active material layer 13; the second active material layer 13 is provided with a second groove 131, and the first surface 114 of the second single-sided empty foil area 117 is covered by the first active material layer 121. The second surface 115 of the second single-sided empty foil area 117 is exposed in the second groove 131; the first tab 14 is at least partially housed in the first groove 121 and is bonded to the first single-sided empty foil area 116 through the first adhesive layer 161, and the first tab 14 is electrically connected to the first conductive layer 111; the second tab 15 is at least partially housed in the second groove 131 and is bonded to the second single-sided empty foil area 117 through the second adhesive layer 162, and the second tab 15 is electrically connected to the second conductive layer 113.

[0061] In some embodiments, the first surface 114 and the second surface 115 are two opposing surfaces of the first current collector 11 in the thickness direction of the first current collector 11. The first active material layer 12 and the second active material layer 13 are disposed on both sides of the first current collector 11, the first active material layer 12 is disposed on the first conductive layer 111, and the second active material layer 13 is disposed on the second conductive layer 113.

[0062] In some embodiments, the first single-sided empty foil area 116 is a segment of the first current collector 11, having a first surface 114 and a second surface 115; the second single-sided empty foil area 117 is a segment of the first current collector 11, having a first surface 114 and a second surface 115.

[0063] In some embodiments, the first current collector 11 is a composite current collector, and the materials of the first conductive layer 111 and the second conductive layer 113 can be the same. The materials of the first conductive layer 111 and the second conductive layer 113 can be aluminum, copper, etc. The first insulating layer 112 can be a polymer layer, such as polypropylene, polyethylene terephthalate, etc.

[0064] In some embodiments, the first groove 121 is a recessed structure disposed on the first active material layer 12. Along the thickness direction of the first current collector 11, the first groove 121 penetrates the first active material layer 12 and extends from the surface of the first active material layer 12 away from the first surface 114 to the first surface 114, so that the first surface 114 of the first single-sided empty foil area 116 is exposed in the first groove 121. Similarly, the second groove 131 is a recessed structure disposed on the second active material layer 13. Along the thickness direction of the first current collector 11, the second groove 131 penetrates the second active material layer 13 and extends from the surface of the second active material layer 13 away from the second surface 115 to the second surface 115, so that the second surface 115 of the second single-sided empty foil area 117 is exposed in the second groove 131.

[0065] In some embodiments, the first tab 14 and the second tab 15 are made of metallic materials, such as copper, aluminum, etc.

[0066] In some embodiments, the material of the first adhesive layer 161 includes epoxy resin, polyurethane, polyethylene, polypropylene, or polyolefin.

[0067] In some embodiments, a portion of the first tab 14 is accommodated in the first groove 121, and this portion of the first tab 14 is bonded to the first surface 114 of the first single-sided empty foil area 116 via the first adhesive layer 161, thereby connecting the first tab 14 to the first conductive layer 111. The first tab 14 and the first conductive layer 111 are electrically connected. For example, the first adhesive layer 161 can be an insulating material, and within the first groove 121, a portion of the first tab 14 can be bonded to the first surface 114 via the first adhesive layer 161, and a portion of the first tab 14 can contact the first surface 114, thereby achieving an electrical connection between the first tab 14 and the first conductive layer 111; or, the first adhesive layer 161 can include a conductive material, and the first tab 14 is bonded to the first surface 114 via the first adhesive layer 161, and the first tab 14 can be electrically connected to the first surface 114 via the conductive material in the first adhesive layer 161. For example, the first adhesive layer 161 is a conductive adhesive.

[0068] In some embodiments, the material of the second adhesive layer 162 includes epoxy resin, polyurethane, polyethylene, polypropylene, or polyolefin.

[0069] In some embodiments, a portion of the second tab 15 is accommodated in the second groove 131, and this portion of the second tab 15 is bonded to the second surface 115 of the second single-sided empty foil area 117 via the second adhesive layer 162, thereby connecting the second tab 15 to the second conductive layer 113. The second tab 15 is electrically connected to the second conductive layer 113. For example, the second adhesive layer 162 can be an insulating material. Within the second groove 131, a portion of the second tab 15 can be bonded to the second surface 115 via the second adhesive layer 162, and a portion of the second tab 15 can contact the second surface 115 to achieve electrical connection between the second tab 15 and the second conductive layer 113; or, the second adhesive layer 162 can include a conductive material, and the second tab 15 is bonded to the second surface 115 via the second adhesive layer 162, and the second tab 15 can be electrically connected to the second surface 115 via the conductive material in the second adhesive layer 162. For example, the second adhesive layer 162 is a conductive adhesive.

[0070] In the above scheme, the first electrode 10 and the second electrode 20 have opposite polarities, which allows metal ions to move between the first electrode 10 and the second electrode 20, thereby realizing the charging and discharging of the electrode assembly 1; the first current collector 11 includes a first conductive layer 111, a first insulating layer 112 and a second conductive layer 113 distributed sequentially along its thickness direction, the first active material layer 12 is disposed on the first surface 114 of the first conductive layer 111, and the second active material layer 13 is disposed on the second surface 115 of the second conductive layer 113, so that metal ions can be inserted into or extracted from the first active material layer 12 and the second active material layer 13 to realize the movement of metal ions. The first current collector 11 includes a first single-sided empty foil area 116 and a second single-sided empty foil area 117. The first surface 114 of the first single-sided empty foil area 116 is bonded to the first electrode tab 14, and the second surface 115 of the first single-sided empty foil area 116 is covered by a second active material layer 13. The first surface 114 of the second single-sided empty foil area 117 is covered by a first active material layer 12, and the second surface 115 of the second single-sided empty foil area 117 is bonded to the second electrode tab 15. Compared to the case where grooves are provided on both the side of the current collector connected to the electrode tab and the side away from the electrode tab, in this application, the first current collector 11 has a second active material layer 13 on the side away from the first electrode tab 14. 3. The first current collector 11 has a first active material layer 12 on the side opposite to the second tab 15, which reduces the loss of active material and makes the electrode assembly 1 have more active material layers, which facilitates the improvement of the energy density of the electrochemical device composed of the electrode assembly 1. At the same time, the first current collector 11 is a composite current collector, with the first tab 14 and the second tab 15 distributed on both sides of the first current collector 11. The first tab 14 is electrically connected to the first conductive layer 111, and the second tab 15 is electrically connected to the second conductive layer 113, so as to facilitate the output or input of electrical energy. The arrangement of the first tab 14 and the second tab 15 increases the number of tabs and can also improve the charge and discharge rate. The first tab 14 is at least partially housed in the first groove 121, and the second tab 15 is at least partially housed in the second groove 131, which not only facilitates the connection between the first tab 14 and the first current collector 11, and the connection between the second tab 15 and the first current collector 11, but also makes the overall thickness of the electrode assembly 1 smaller, so that the energy density of the electrochemical device with this electrode assembly 1 is larger. The first tab 14 is bonded to the first conductive layer 111 via the first adhesive layer 161, and the second tab 15 is bonded to the second conductive layer 113 via the second adhesive layer 162. This method is easy to operate and has a lower manufacturing difficulty. By bonding the first tab 14 to the first conductive layer 111 via the first adhesive layer 161 and the second tab 15 to the second conductive layer 113 via the second adhesive layer 162, there is no need to weld the tabs, which reduces the safety risk of the first current collector 11 due to solder cracking.

[0071] In some embodiments, the electrode assembly 1 has a wound structure.

[0072] Please refer to Figure 1 and further refer to Figure 2 , Figure 2 This is a schematic diagram of the structure of the first electrode provided in some embodiments of this application.

[0073] In some embodiments, along the winding direction of the electrode assembly 1, the width W1 of the first groove 121 satisfies 5mm≤W1≤15mm. For example, W1 can be 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm or 15mm, etc.

[0074] Along the winding axis of the electrode assembly 1, the length L1 of the first groove 121 satisfies 5mm≤L1≤25mm. For example, L1 can be 5mm, 10mm, 15mm, 20mm or 25mm, etc.

[0075] By ensuring that the width W1 of the first groove 121 along the winding direction of the electrode assembly 1 satisfies 5mm≤W1≤15mm, and the length L1 of the first groove 121 along the winding axis of the electrode assembly 1 satisfies 5mm≤L1≤25mm, on the one hand, the first current collector 11 and the first tab 14 can have a larger connection area, and the first current collector 11 and the first tab 14 can have a larger flow capacity; on the other hand, the volume loss of the first active material layer 12 can be smaller, and the energy density of the electrochemical device with this electrode assembly 1 is greater.

[0076] In some embodiments, along the winding direction of the electrode assembly 1, the width W2 of the second groove 131 satisfies 5mm≤W2≤15mm. For example, W2 can be 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm or 15mm, etc.

[0077] Along the winding axis of electrode assembly 1, the length L2 of the second groove 131 satisfies 5mm≤L2≤25mm. For example, L2 can be 5mm, 10mm, 15mm, 20mm or 25mm, etc.

[0078] By ensuring that the width W2 of the second groove 131 along the winding direction of the electrode assembly 1 satisfies 5mm≤W2≤15mm, and the length L2 of the second groove 131 along the winding axis of the electrode assembly 1 satisfies 5mm≤L2≤25mm, on the one hand, the first current collector 11 and the second tab 15 can have a larger connection area, and the first current collector 11 and the second tab 15 can have a larger flow capacity; on the other hand, the volume loss of the second active material layer 13 can be reduced, and the energy density of the electrochemical device with this electrode assembly 1 is greater.

[0079] Please refer to Figure 1 and Figure 2 In some embodiments, the first tab 14 includes a first portion 141 that overlaps with the first current collector 11. When viewed along the thickness direction of the first current collector 11, the first portion 141 is located within the first groove 121 and overlaps with the first current collector 11.

[0080] In some embodiments, the thickness direction of the first portion 141 is parallel to the thickness direction of the first current collector 11.

[0081] The thickness H1 of the first part 141 satisfies 20μm≤H1≤120μm. For example, H1 can be 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm or 120μm, etc.

[0082] Along the winding direction of electrode assembly 1, the width W3 of the first part 141 satisfies 2mm≤W3≤14mm. For example, W3 can be 2mm, 4mm, 6mm, 8mm, 10mm, 12mm or 14mm, etc.

[0083] Along the winding axis of electrode assembly 1, the length L3 of the first part 141 satisfies 2mm≤L3≤24mm. For example, L3 can be 2mm, 4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm or 24mm, etc.

[0084] By ensuring that the thickness H1 of the first portion 141 satisfies 20μm≤H1≤120μm; the width W3 of the first portion 141 along the winding direction of the electrode assembly 1 satisfies 2mm≤W3≤14mm; and the length L3 of the first portion 141 along the winding axis of the electrode assembly 1 satisfies 2mm≤L3≤24mm, on the one hand, the first tab 14 and the first current collector 11 have a larger connection area, and the first tab 14 and the first fluid have a larger flow capacity; on the other hand, the area of ​​the first groove 121 can be smaller, the volume loss of the first active material layer 12 can be smaller, and the energy density of the electrochemical device with this electrode assembly 1 is higher.

[0085] In some embodiments, the second tab 15 includes a second portion 151 that overlaps with the first current collector 11. When viewed along the thickness direction of the first current collector 11, the second portion 151 is located within the second groove 131 and overlaps with the second current collector.

[0086] In some embodiments, the thickness direction of the second portion 151 is parallel to the thickness direction of the first current collector 11.

[0087] The thickness H2 of the second part 151 satisfies 20μm≤H2≤120μm. For example, H2 can be 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm or 120μm, etc.

[0088] Along the winding direction of electrode assembly 1, the width W4 of the second part 151 satisfies 2mm≤W4≤14mm. For example, W4 can be 2mm, 4mm, 6mm, 8mm, 10mm, 12mm or 14mm, etc.

[0089] Along the winding axis of electrode assembly 1, the length L4 of the second part 151 satisfies 2mm≤L4≤24mm. For example, L4 can be 2mm, 4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm or 24mm, etc.

[0090] By ensuring that the thickness H2 of the second part 151 satisfies 20μm≤H2≤120μm; the width W4 of the second part 151 along the winding direction of the electrode assembly 1 satisfies 2mm≤W4≤14mm; and the length L4 of the second part 151 along the winding axis of the electrode assembly 1 satisfies 2mm≤L4≤24mm, on the one hand, the second tab 15 and the first current collector 11 have a larger connection area, and the second tab 15 and the first fluid have a larger flow capacity; on the other hand, the area of ​​the second groove 131 can be smaller, the volume loss of the second active material layer 13 can be smaller, and the energy density of the electrochemical device with this electrode assembly 1 is higher.

[0091] In some embodiments, the electrode assembly 1 has a wound structure; the first electrode 10 has a winding start end 181 and a winding end end 182. The first electrode 10 has a continuous strip structure. According to the winding method of the electrode assembly 1, the winding start end 181 refers to the end of the first electrode 10 closest to the winding axis of the electrode assembly 1, and the winding end end 182 refers to the end of the first electrode 10 furthest from the winding axis of the electrode assembly 1.

[0092] Along the winding direction of the electrode assembly 1, the first groove 121 is closer to the winding start end 181 than the second groove 131; along the winding direction of the electrode assembly 1, the distance between the first groove 121 and the winding start end 181 is M1, the distance between the second groove 131 and the winding end end 182 is M2, and the length of the first electrode 10 is M3, satisfying 0.25≤M1 / M3≤0.35; 0.25≤M2 / M3≤0.35.

[0093] It should be noted that, for ease of description, Figure 1The first electrode 10 is shown in the unfolded state. M1 is the distance between the end of the first groove 121 near the winding start end 181 and the winding start end 181. M2 is the distance between the end of the second groove 131 near the winding end end 182 and the winding end end 182. M3 is the length of the first electrode 10 when unfolded.

[0094] When M1 / M3 is large, M1 is large, and the distance between the first groove 121 and the second groove 131 is small, which easily leads to interference between the first groove 121 and the second groove 131. When M1 / M3 is small, M1 is small, and the distance between the first groove 121 and the winding start end 181 is small, and the distance between the second groove 131 and the winding end end 182 is small. The distance between the first groove 121 and the second groove 131 is large, and the current flow path from the middle of the winding direction towards the first and second electrodes is longer, resulting in poor current conduction capability.

[0095] By setting the distance M1 between the first groove 121 and the winding start end, the distance M2 between the second groove 131 and the winding end end along the winding direction of the electrode assembly 1, and the length M3 of the first electrode 10, the following conditions are met: 0.25≤M1 / M3≤0.35, 0.25≤M2 / M3≤0.35. This facilitates manufacturing and reduces the risk of interference between the first and second grooves. It also facilitates the flow of current between the first current collector and the first and second electrodes, facilitating the output and input of electrical energy and improving charging and discharging efficiency.

[0096] Please refer to Figure 3 , Figure 3 This is a schematic diagram of the assembly of multiple first protrusions and a first conductive layer provided in some embodiments of this application. Figure 3 This is a cross-sectional view of a portion of the structure of the first electrode. In some embodiments, a plurality of first protrusions 142 are formed on the side of the first electrode tab 14 facing the first current collector 11, and at least a portion of the plurality of first protrusions 142 are in contact with the first conductive layer 111.

[0097] At the connection between the first electrode 14 and the first current collector 11, the first electrode 14 has a fifth surface facing the first current collector 11, and a first protrusion 142 is formed on the side of the first electrode 14 facing the first current collector 11. The first protrusion 142 protrudes toward the first current collector 11 so that the first electrode 14 contacts the first conductive layer 111 through the first protrusion 142, thereby realizing the electrical connection between the first electrode 14 and the first current collector 11.

[0098] In some embodiments, the plurality of first protrusions 142 are arranged in a matrix to facilitate manufacturing.

[0099] In some embodiments, the first tab 14 can be formed into a first protrusion 142 by means of stamping, laser, cold heading, etching, etc.

[0100] In some embodiments, the shape of the first protrusion 142 can be in various forms, for example, the first protrusion 142 can be a cylinder, a cone, a polygonal prism, etc.

[0101] In some embodiments, a first adhesive layer 161 is accommodated between two adjacent first protrusions 142. When assembling the first tab 14 with the first conductive layer 111, the first adhesive layer 161 can be first coated on the fifth surface of the first tab 14, and then the first tab 14 coated with the first adhesive layer 161 is bonded to the first conductive layer 111. The first adhesive layer 161 is activated by hot pressing, completing the bonding and fixing between the first tab 14 and the first current collector 11. Multiple first protrusions 142 are spaced apart, and the area between adjacent first protrusions 142 can accommodate the first adhesive. The first protrusion 142 contacts the first conductive layer 111, and the first adhesive bonds the fifth surface and the first surface 114, achieving bonding between the first tab 14 and the first current collector 11 while simultaneously electrically connecting the first tab 14 to the first conductive layer 111.

[0102] By forming a plurality of first protrusions 142 on the side of the first electrode 14 facing the first current collector 11, the first electrode 14 can be conveniently positioned to position the first adhesive layer 161. The first adhesive layer 161 can be accommodated in the area between two adjacent first protrusions 142, thereby increasing the bonding effect between the first electrode 14 and the first conductive layer 111. At least a portion of the plurality of first protrusions 142 contacts the first conductive layer 111 to achieve electrical connection between the first electrode 14 and the first conductive layer 111.

[0103] In some embodiments, a plurality of second protrusions (not shown) are formed on the side of the second tab 15 facing the first current collector 11, and at least a portion of the plurality of second protrusions are in contact with the second conductive layer 113.

[0104] The second protrusion can be designed in the same way as the first protrusion 142.

[0105] By forming a plurality of second protrusions on the side of the second tab 15 facing the first current collector 11, the second tab 15 can be conveniently positioned to the second adhesive layer 162. The second adhesive layer 162 can be accommodated in the area between two adjacent second protrusions, thereby increasing the bonding effect between the second tab 15 and the second conductive layer 113. At least a portion of the plurality of second protrusions contacts the second conductive layer 113 to achieve electrical connection between the second tab 15 and the second conductive layer 113.

[0106] Please refer to Figure 1 and Figure 3In some embodiments, the first electrode 10 further includes a first insulating member 171, which is disposed on the side of the first electrode tab 14 away from the first current collector 11 and covers the first electrode tab 14.

[0107] In some embodiments, the first insulating member 171 can be an adhesive tape, which has a simple structure and is easy to position.

[0108] In some embodiments, the first insulating member 171 may be sheet-shaped, and the thickness direction of the first insulating member 171 is parallel to the thickness direction of the first current collector 11.

[0109] In some embodiments, the first insulating member 171 can be bonded to the first active material layer 12. When viewed along the thickness direction of the first current collector 11, the first insulating member 171 covers the first groove 121. On the one hand, this facilitates the assembly and positioning of the first insulating member 171; on the other hand, the first insulating member 171 can cover the first tab 14.

[0110] The first insulating element 171 covers the first tab 14, enabling it to insulate the first tab 14 from the second electrode 20 and reducing the possibility of a short circuit between the first electrode 10 and the second electrode 20. Since the surface of the first tab 14 has burrs, the first insulating element 171 also isolates the burrs, making it less likely for them to contact the second electrode 20 and cause a short circuit or damage to the second electrode 20.

[0111] In some embodiments, the first electrode 10 further includes a second insulating member 172, which is disposed on the side of the second electrode tab 15 away from the first current collector 11 and covers the second electrode tab 15.

[0112] In some embodiments, the second insulating member 172 can be an adhesive tape, which has a simple structure and facilitates the positioning of the second insulating member 172.

[0113] In some embodiments, the second insulating member 172 may be sheet-like, and the thickness direction of the second insulating member 172 is parallel to the thickness direction of the first insulating member 171.

[0114] In some embodiments, the second insulating member 172 can be bonded to the second active material layer 13. When viewed along the thickness direction of the first current collector 11, the second insulating member 172 covers the second groove 131. On the one hand, this facilitates the assembly and positioning of the second insulating member 172; on the other hand, the second insulating member 172 can cover the second tab 15.

[0115] The second insulating element 172 covers the second tab 15, enabling it to insulate the second tab 15 from the second electrode 20 and reducing the possibility of a short circuit between the first electrode 10 and the second electrode 20. Since the surface of the second tab 15 has burrs, the second insulating element 172 also isolates these burrs, making it less likely for them to contact the second electrode 20 and cause a short circuit or damage to the second electrode 20.

[0116] Please refer to Figure 1 and Figure 4 , Figure 4 Cross-sectional views of electrode assemblies provided in other embodiments of this application. Figure 4 This is a cross-sectional view of the electrode assembly in its unfolded state. In some embodiments, the second electrode 20 includes a second current collector 21, a third active material layer 22, a fourth active material layer 23, and a third tab 24. The second current collector 21 has a third surface 211 and a fourth surface 212 disposed opposite to each other, and includes a third single-sided empty foil region 213. The third active material layer 22 is disposed on the third surface 211 and has a third groove 221. The third surface 211 of the third single-sided empty foil region 213 is exposed in the third groove 221. The fourth active material layer 23 is disposed on the fourth surface 212, and the fourth surface 212 of the third single-sided empty foil region 213 is covered by the fourth active material layer 23. The third tab 24 is at least partially accommodated in the third groove 221 and is bonded to the third single-sided empty foil region 213 through a third adhesive layer 261. The third tab 24 is electrically connected to the third single-sided empty foil region 213.

[0117] In some embodiments, the third surface 211 and the fourth surface 212 are two opposing surfaces of the second current collector 21 in the thickness direction of the second current collector 21, and the third active material layer 22 and the fourth active material layer 23 are disposed on both sides of the second current collector 21.

[0118] In some embodiments, the third single-sided empty foil region 213 is a segment of the second current collector 21, having a third surface 211 and a fourth surface 212.

[0119] In some embodiments, the material of the second current collector 21 may be aluminum, copper, etc.

[0120] In some embodiments, the third groove 221 is a recessed structure disposed on the third active material layer 22. Along the thickness direction of the second current collector 21, the third groove 221 penetrates the third active material layer 22. The third groove 221 extends from the surface of the third active material layer 22 that is away from the third surface 211 to the third surface 211, so that the third surface 211 of the third single-sided empty foil area 213 is exposed in the third groove 221.

[0121] In some embodiments, the material of the third adhesive layer 261 includes epoxy resin, polyurethane, polyethylene, polypropylene, or polyolefin.

[0122] In some embodiments, a portion of the third tab 24 is accommodated in the third groove 221, and this portion of the third tab 24 is bonded to the third surface 211 of the third single-sided empty foil area 213 via the third adhesive layer 261 to achieve connection between the third tab 24 and the second current collector 21. For example, the third adhesive layer 261 can be an insulating material. Within the third groove 221, a portion of the third tab 24 can be bonded to the third surface 211 via the third adhesive layer 261, and a portion of the third tab 24 can contact the third surface 211 to achieve electrical connection between the third tab 24 and the second current collector 21; or, the third adhesive layer 261 can include a conductive material, and the third tab 24 is bonded to the third surface 211 via the third adhesive layer 261, and the third tab 24 can be electrically connected to the third surface 211 via the conductive material in the third adhesive layer 261. For example, the third adhesive layer 261 is a conductive adhesive.

[0123] In some embodiments, please refer to Figure 1 The third surface 211 can be the surface of the second current collector 21 facing the first active material layer 12; or, please refer to Figure 4 The third surface 211 can be the surface of the second current collector 21 that is away from the first active material layer 12.

[0124] In the above scheme, the third active material layer 22 is disposed on the third surface 211, and the fourth active material layer 23 is disposed on the fourth surface 212, so that metal ions can be inserted or extracted into the third active material layer 22 and the fourth active material layer 23 to realize the movement of metal ions. The second current collector 21 includes a third single-sided empty foil area 213, the third surface 211 of the third single-sided empty foil area 213 is bonded to the third electrode tab 24, and the fourth surface 212 of the third single-sided empty foil area 213 is covered by the fourth active material layer 23. Compared with the case where grooves are provided on both the side of the current collector connected to the electrode tab and the side away from the electrode tab, in this application, the second current collector 21 is provided with the fourth active material layer 23 on the side away from the third electrode tab 24, which reduces the loss of active material and makes the electrode assembly 1 have more active material layers, which is conducive to improving the energy density of the electrochemical device composed of the electrode assembly 1. The third tab 24 is at least partially housed within the third groove 221, which facilitates the connection between the third tab 24 and the second current collector 21, and also reduces the overall thickness of the electrode assembly 1, resulting in a higher energy density in the electrochemical device equipped with this electrode assembly 1. The third tab 24 is bonded to the third single-sided empty foil area 213 via the third adhesive layer 261, which facilitates operation and reduces manufacturing difficulty.

[0125] Please refer to Figure 1 and Figure 4 In some embodiments, the second electrode 20 further includes a third insulating member 271, which is disposed on the side of the third electrode tab 24 away from the second current collector 21 and covers the third electrode tab 24.

[0126] In some embodiments, the third insulating member 271 can be an adhesive tape, which has a simple structure and facilitates the positioning of the third insulating member 271.

[0127] In some embodiments, the third insulating member 271 may be sheet-like, and the thickness direction of the third insulating member 271 is parallel to the thickness direction of the second current collector 21.

[0128] In some embodiments, the third insulating member 271 can be bonded to the third active material layer 22. When viewed along the thickness direction of the second current collector 21, the third insulating member 271 covers the third groove 221. On the one hand, this facilitates the assembly and positioning of the third insulating member 271; on the other hand, the third insulating member 271 can cover the third tab 24.

[0129] The third insulating element 271 covers the third tab 24, enabling it to insulate the third tab 24 from the first electrode 10 and reducing the possibility of a short circuit between the second electrode 20 and the first electrode 10. Because the surface of the third tab 24 has burrs, the third insulating element 271 also isolates the burrs, making it less likely for them to contact the first electrode 10 and cause a short circuit or damage to the first electrode 10.

[0130] Please refer to Figure 5 , Figure 5 A cross-sectional view of an electrode assembly provided in some embodiments of this application. Figure 5 This is a partial structural schematic diagram of the electrode assembly in a wound state. In some embodiments, the first electrode 10 further includes a fourth insulating member 173, which is disposed on the first active material layer 12. When viewed along the thickness direction of the first current collector 11, the projection of the fourth insulating member 173 covers the third electrode tab 24.

[0131] In some embodiments, the fourth insulating element 173 can be an adhesive tape, which can be bonded to the first active material layer 12. The structure is simple and easy to position the fourth insulating element 173.

[0132] In some embodiments, the fourth insulating member 173 may be sheet-like, and the thickness direction of the fourth insulating member 173 is parallel to the thickness direction of the first current collector 11.

[0133] In some embodiments, when viewed along the thickness direction of the first current collector 11, the fourth insulating member 173 is correspondingly disposed with the third electrode tab 24. For example, the projection of the fourth insulating member 173 can fall into the third groove 221, and the thickness of the electrode assembly 1 can be smaller, so that the energy density of the electrochemical device provided with this electrode assembly 1 can be larger. For another example, the projection of the fourth insulating member 173 can cover the third groove 221, and when viewed along the thickness direction of the first current collector 11, the fourth insulating member 173 and the second electrode 20 have a large overlap area.

[0134] By making the projection of the fourth insulating member 173 cover the third electrode tab 24 when viewed along the thickness direction of the first current collector 11, the fourth insulating member 173 can isolate the burrs of the third electrode tab 24, making it difficult for the burrs to come into contact with the first active material layer 12 to cause a short circuit or damage to the first electrode 10.

[0135] Please refer to Figure 5 In some embodiments, the second electrode 20 further includes a fifth insulating element 272, which is disposed on the third active material layer 22. When viewed along the thickness direction of the second current collector 21, the projection of the fifth insulating element 272 covers the first electrode tab 14.

[0136] In some embodiments, the fifth insulating element 272 can be an adhesive tape, and the fifth insulating element 272 can be bonded to the third active material layer 22. The structure is simple and easy to position the fifth insulating element 272.

[0137] In some embodiments, the fifth insulating member 272 may be sheet-like, and the thickness direction of the fifth insulating member 272 is parallel to the thickness direction of the second current collector 21.

[0138] In some embodiments, when viewed along the thickness direction of the second current collector 21, the fifth insulating member 272 is correspondingly disposed with the first electrode tab 14. For example, the projection of the fifth insulating member 272 can fall into the first groove 121, and the thickness of the electrode assembly 1 can be small, so that the energy density of the electrochemical device provided with this electrode assembly 1 can be large. For another example, the projection of the fifth insulating member 272 can cover the first groove 121, and when viewed along the thickness direction of the second current collector 21, the fifth insulating member 272 and the first electrode 10 have a large overlap area.

[0139] By making the projection of the fifth insulating element 272 cover the first electrode tab 14 when viewed along the thickness direction of the second current collector 21, the fifth insulating element 272 can isolate the burrs of the first electrode tab 14, and further make it difficult for the burrs to come into contact with the second active material layer 13 to cause a short circuit or damage to the second electrode 20.

[0140] In some embodiments, the second electrode 20 further includes a sixth insulating member 273, which is disposed on the fourth active material layer 23. When viewed along the thickness direction of the second current collector 21, the projection of the sixth insulating member 273 covers the second electrode tab 15.

[0141] In some embodiments, the sixth insulating element 273 can be an adhesive tape, and the sixth insulating element 273 can be bonded to the fourth active material layer 23. The structure is simple and easy to position the sixth insulating element 273.

[0142] In some embodiments, the sixth insulating member 273 may be sheet-like, and the thickness direction of the sixth insulating member 273 is parallel to the thickness direction of the second current collector 21.

[0143] In some embodiments, when viewed along the thickness direction of the second current collector 21, the sixth insulating member 273 is correspondingly disposed with the second electrode tab 15. For example, the projection of the sixth insulating member 273 can fall into the second groove 131, and the thickness of the electrode assembly 1 can be smaller, so that the energy density of the electrochemical device provided with this electrode assembly 1 can be larger. For another example, the projection of the sixth insulating member 273 can cover the second groove 131, and when viewed along the thickness direction of the second current collector 21, the sixth insulating member 273 and the first electrode 10 have a large overlap area.

[0144] By making the projection of the sixth insulating member 273 cover the second electrode tab 15 when viewed along the thickness direction of the second current collector 21, the sixth insulating member 273 can isolate the burrs of the second electrode tab 15, and further make it difficult for the burrs to come into contact with the second active material layer 13 to cause a short circuit or damage to the second electrode 20.

[0145] Please refer to Figure 1 and Figure 4 and further refer to Figure 6 , Figure 6 This is a schematic diagram of the structure of the second electrode provided in some embodiments of this application.

[0146] In some embodiments, along the winding direction of the electrode assembly 1, the width W5 of the third groove 221 satisfies 5mm≤W5≤15mm. For example, W5 can be 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm or 15mm, etc.

[0147] In some embodiments, along the winding axis direction of the electrode assembly 1, the length L5 of the third groove 221 satisfies 5mm≤L5≤25mm. For example, L5 can be 5mm, 10mm, 15mm, 20mm or 25mm, etc.

[0148] By ensuring that the width W5 of the third groove 221 along the winding direction of the electrode assembly 1 satisfies 5mm≤W5≤15mm, and the length L5 of the third groove 221 along the winding axis of the electrode assembly 1 satisfies 5mm≤L5≤25mm, on the one hand, the second current collector 21 and the third tab 24 have a larger connection area, and the second current collector 21 and the third tab 24 have a larger flow capacity; on the other hand, the volume loss of the third active material layer 22 is smaller, and the energy density of the electrochemical device with this electrode assembly 1 is higher.

[0149] In some embodiments, the third tab 24 includes a third portion 241 connected to the third single-sided empty foil region 213. When viewed along the thickness direction of the second current collector 21, the third portion 241 is located within the third groove 221 and overlaps with the second current collector 21.

[0150] In some embodiments, the thickness direction of the third portion 241 is parallel to the thickness direction of the second current collector 21.

[0151] The thickness H3 of the third part 241 satisfies 20μm≤H3≤120μm. For example, H3 can be 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm or 120μm, etc.

[0152] Along the winding direction of electrode assembly 1, the width W6 of the third part 241 satisfies 2mm≤W6≤14mm. For example, W6 can be 2mm, 4mm, 6mm, 8mm, 10mm, 12mm or 14mm, etc.

[0153] Along the winding axis of electrode assembly 1, the length L6 of the third part 241 satisfies 2mm≤L6≤24mm. For example, L6 can be 2mm, 4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm or 24mm, etc.

[0154] By ensuring that the thickness H3 of the third part 241 satisfies 20μm≤H3≤120μm; the width W6 of the third part 241 along the winding direction of the electrode assembly 1 satisfies 2mm≤W6≤14mm; and the length L6 of the third part 241 along the winding axis of the electrode assembly 1 satisfies 2mm≤L6≤24mm, on the one hand, the third tab 24 and the second current collector 21 have a larger connection area, and the third tab 24 and the second current collector have a larger flow capacity; on the other hand, the area of ​​the third groove 221 can be smaller, the volume loss of the third active material layer 22 can be smaller, and the energy density of the electrochemical device with this electrode assembly 1 is higher.

[0155] Please refer to Figure 7 , Figure 7 A cross-sectional view of an electrode assembly provided in some embodiments of this application. Figure 7 This is a cross-sectional view of the electrode assembly in its unfolded state. In some embodiments, the second current collector 21 includes a third conductive layer 214, a second insulating layer 215, and a fourth conductive layer 216 sequentially distributed along its thickness direction. The third surface 211 is the surface of the third conductive layer 214 facing away from the second insulating layer 215, and the fourth surface 212 is the surface of the fourth conductive layer 216 facing away from the second insulating layer 215. The second current collector 21 also includes a fourth single-sided empty foil region 217. The fourth active material layer 23 is provided with a fourth groove 231. The third surface 211 of the fourth single-sided empty foil region 217 is covered by the third active material layer 22, and the fourth surface 212 of the fourth single-sided empty foil region 217 is exposed in the fourth groove 231. The second electrode 20 also includes a fourth electrode tab 25. The fourth electrode tab 25 is at least partially accommodated in the fourth groove 231 and is bonded to the fourth single-sided empty foil region 217 through a fourth adhesive layer 262. The third electrode tab 24 is electrically connected to the third conductive layer 214, and the fourth electrode tab 25 is electrically connected to the fourth conductive layer 216.

[0156] In some embodiments, the second current collector 21 is a composite current collector, and the materials of the third conductive layer 214 and the fourth conductive layer 216 can be the same. The materials of the third conductive layer 214 and the fourth conductive layer 216 can be aluminum, copper, etc. The second insulating layer 215 can be a polymer layer, such as polypropylene, polyethylene terephthalate, etc.

[0157] In some embodiments, the third surface 211 may be the surface of the second current collector 21 facing the first active material layer 12, and the fourth surface 212 may be the surface of the second current collector 21 facing away from the first active material layer 12; or, the third surface 211 may be the surface of the second current collector 21 facing away from the first active material layer 12, and the fourth surface 212 may be the surface of the second current collector 21 facing the first active material layer 12.

[0158] In some embodiments, the fourth single-sided empty foil region 217 is a segment of the second current collector 21, having a third surface 211 and a fourth surface 212.

[0159] In some embodiments, the fourth groove 231 is a recessed structure disposed on the fourth active material layer 23. Along the thickness direction of the second current collector 21, the fourth groove 231 penetrates the fourth active material layer 23. The fourth groove 231 extends from the surface of the fourth active material layer 23 away from the fourth surface 212 to the fourth surface 212, so that the fourth surface 212 of the fourth single-sided empty foil area 217 is exposed in the fourth groove 231.

[0160] In some embodiments, the material of the fourth adhesive layer 262 includes epoxy resin, polyurethane, polyethylene, polypropylene, or polyolefin.

[0161] In some embodiments, a portion of the fourth tab 25 is accommodated in the fourth groove 231, and this portion of the fourth tab 25 is bonded to the fourth surface 212 of the fourth single-sided empty foil area 217 via the fourth adhesive layer 262 to achieve connection between the fourth tab 25 and the second current collector 21. The fourth tab 25 is electrically connected to the second current collector 21. For example, the fourth adhesive layer 262 can be an insulating material. Within the fourth groove 231, a portion of the fourth tab 25 can be bonded to the fourth surface 212 via the fourth adhesive layer 262, and a portion of the fourth tab 25 can contact the fourth surface 212 to achieve electrical connection between the fourth tab 25 and the second current collector 21. Alternatively, the fourth adhesive layer 262 can include a conductive material, and the fourth tab 25 is bonded to the fourth surface 212 via the fourth adhesive layer 262. The fourth tab 25 can be electrically connected to the fourth surface 212 via the conductive material in the fourth adhesive layer 262. For example, the fourth adhesive layer 262 can be a conductive adhesive.

[0162] In the above scheme, the second current collector 21 is a composite current collector, and the third tab 24 and the fourth tab 25 are distributed on both sides of the first current collector 11. The third tab 24 is electrically connected to the third conductive layer 214, and the fourth tab 25 is electrically connected to the fourth conductive layer 216 to facilitate the conduction or introduction of electrical energy. The arrangement of the third tab 24 and the fourth tab 25 increases the number of tabs and can also improve the charge and discharge rate. The fourth tab 25 is at least partially accommodated in the fourth groove 231, which facilitates the connection between the fourth tab 25 and the second current collector 21 and also makes the overall thickness of the electrode assembly 1 smaller, resulting in a higher energy density of the electrochemical device with this electrode assembly 1. The fourth tab 25 is bonded to the fourth single-sided empty foil area 217 through the fourth adhesive layer 262, which is convenient for operation and has low processing and manufacturing difficulty.

[0163] Please refer to Figure 7 The second electrode also includes a seventh insulating member 274, which is disposed on the side of the fourth electrode tab 25 away from the second current collector 21 and covers the fourth electrode tab 25.

[0164] The seventh insulating element 274 covers the fourth tab 25, enabling it to insulate the fourth tab 25 from the first electrode 10 and reducing the possibility of a short circuit between the second electrode 20 and the first electrode 10. Because the surface of the fourth tab 25 has burrs, the seventh insulating element 274 also isolates these burrs, making it less likely for them to contact the first electrode 10 and cause a short circuit or damage to the first electrode 10.

[0165] Please refer to Figure 6 and Figure 7In some embodiments, along the winding direction of the electrode assembly 1, the width of the fourth groove 231 is W7, which satisfies 5mm≤W7≤15mm. For example, W7 can be 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm or 15mm, etc.

[0166] In some embodiments, the length of the fourth groove 231 along the winding axis of the electrode assembly 1 is L7, satisfying 5mm≤L7≤25mm. For example, L7 can be 5mm, 10mm, 15mm, 20mm or 25mm, etc.

[0167] By ensuring that the width W7 of the fourth groove 231 along the winding direction of the electrode assembly 1 satisfies 5mm≤W7≤15mm, and the length L7 of the fourth groove 231 along the winding axis of the electrode assembly 1 satisfies 5mm≤L7≤25mm, on the one hand, the second current collector 21 and the fourth tab 25 have a larger connection area, and the second current collector 21 and the fourth tab 25 have a larger flow capacity; on the other hand, the volume loss of the fourth active material layer 23 is smaller, and the energy density of the electrochemical device with this electrode assembly 1 is higher.

[0168] In some embodiments, the fourth tab 25 includes a fourth portion 251 connected to the fourth single-sided empty foil region 217. When viewed along the thickness direction of the second current collector 21, the fourth portion 251 is located within the fourth groove 231 and overlaps with the second current collector 21.

[0169] In some embodiments, the thickness direction of the fourth portion 251 is parallel to the thickness direction of the second current collector 21.

[0170] The thickness of part 251 is H8, which satisfies 20μm≤H8≤120μm. For example, H8 can be 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm or 120μm, etc.

[0171] Along the winding direction of electrode assembly 1, the width of the fourth part 251 is W8, which satisfies 2mm≤W8≤14mm. For example, W8 can be 2mm, 4mm, 6mm, 8mm, 10mm, 12mm or 14mm, etc.

[0172] Along the winding axis of electrode assembly 1, the length of the fourth part 251 is L8, which satisfies 2mm≤L8≤24mm. For example, L8 can be 2mm, 4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm or 24mm, etc.

[0173] By ensuring that the thickness H8 of the fourth part 251 satisfies 20μm≤H8≤120μm; the width W8 of the fourth part 251 along the winding direction of the electrode assembly 1 satisfies 2mm≤W8≤14mm; and the length L8 of the fourth part 251 along the winding axis of the electrode assembly 1 satisfies 2mm≤L8≤24mm, on the one hand, the fourth tab 25 and the second current collector 21 have a larger connection area, and the fourth tab 25 and the second current collector have a larger flow capacity; on the other hand, the area of ​​the fourth groove 231 can be smaller, the volume loss of the fourth active material layer 23 can be smaller, and the energy density of the electrochemical device with this electrode assembly 1 is higher.

[0174] In some embodiments, the thicknesses of the first conductive layer 111, the second conductive layer 113, the third conductive layer 214, and the fourth conductive layer 216 are all between 0.2 μm and 3 μm. A thickness greater than 0.2 μm allows the conductive layer to possess good conductivity, while a thickness less than 3 μm ensures that the energy density of the battery is not excessively reduced. Furthermore, since the composite current collector has an insulating layer in the middle, a vapor deposition method is required to deposit the conductive layer on the insulating layer; therefore, the thickness cannot be too thick.

[0175] In some embodiments, the first electrode 10 is a positive electrode and the second electrode 20 is a negative electrode.

[0176] The first electrode 10 is a positive electrode, and the first tab 14 and the second tab 15 are positive tabs. Compared with a single positive tab, the two positive tab structures of this application can reduce the internal resistance of the electrochemical device, increase the charging and discharging speed, and reduce the charging temperature rise.

[0177] Please refer to Figure 1This application provides an electrode assembly 1, including a first electrode 10 and a second electrode 20 with opposite polarities. The first electrode 10 includes a first current collector 11, a first active material layer 12, a second active material layer 13, a first tab 14, a second tab 15, a first insulating member 171, and a second insulating member 172. The first current collector 11 includes a first conductive layer 111, a first insulating layer 112, and a second conductive layer 113 sequentially distributed along its thickness direction. The first conductive layer 111 has a first surface 114 facing away from the first insulating layer 112, and the second conductive layer 113 has a second surface 115 facing away from the first insulating layer 112. The first active material layer 12 is disposed on the first surface 114, and the second active material layer 13 is disposed on the second surface 115. The first current collector 11 includes a first single-sided empty foil area 116 and a second single-sided empty foil area 117; the first active material layer 12 is provided with a first groove 121, the first surface 114 of the first single-sided empty foil area 116 is exposed in the first groove 121, and the second surface 115 of the first single-sided empty foil area 116 is covered by the second active material layer 13; the second active material layer 13 is provided with a second groove 131, the first surface 114 of the second single-sided empty foil area 117 is covered by the first active material layer 12, and the second surface 115 of the second single-sided empty foil area 117 is exposed in the second groove 131; the first tab 14 is at least partially accommodated in the first groove 121 and is bonded to the first single-sided empty foil area 116 through a first adhesive layer 161; the second tab 15 is at least partially accommodated in the second groove 131 and is bonded to the second single-sided empty foil area 117 through a second adhesive layer 162. The first insulating member 171 is disposed on the side of the first electrode 14 opposite to the first current collector 11 and covers the first electrode 14. The second insulating member 172 is disposed on the side of the second electrode 15 opposite to the first current collector 11 and covers the second electrode 15.

[0178] The second electrode 20 includes a second current collector 21, a third active material layer 22, a fourth active material layer 23, a third tab 24, and a third insulating member 271. The second current collector 21 has a third surface 211 and a fourth surface 212 disposed opposite to each other, and includes a third single-sided empty foil area 213. The third active material layer 22 is disposed on the third surface 211, and has a third groove 221. The third surface 211 of the third single-sided empty foil area 213 is exposed in the third groove 221. The fourth active material layer 23 is disposed on the fourth surface 212, and the fourth surface 212 of the third single-sided empty foil area 213 is covered by the fourth active material layer 23. The third tab 24 is at least partially accommodated in the third groove 221 and is bonded to the third single-sided empty foil area 213 by a third adhesive layer 261. The third insulating member 271 is disposed on the side of the third tab 24 opposite to the second current collector 21 and covers the third tab 24.

[0179] This application also provides an electrochemical device including an electrode assembly 1 provided according to any of the above embodiments.

[0180] This application also provides an electrical device, including an electrochemical device according to the above embodiments, the electrochemical device being used to provide electrical energy.

[0181] The electrical equipment can be any of the aforementioned devices or systems that utilize electrochemical devices.

[0182] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An electrode assembly, characterized by, The electrode assembly comprises a first tab and a second tab with opposite polarities, the first tab comprising: a first current collector comprising a first conductive layer, a first insulating layer and a second conductive layer arranged in sequence along the thickness direction of the first current collector, the first conductive layer having a first surface facing away from the first insulating layer, and the second conductive layer having a second surface facing away from the first insulating layer; a first active material layer arranged on the first surface; a second active material layer arranged on the second surface; wherein the first current collector comprises a first single-sided hollow foil region and a second single-sided hollow foil region; the first active material layer is provided with a first groove, the first surface of the first single-sided hollow foil region is exposed to the first groove, and the second surface of the first single-sided hollow foil region is covered by the second active material layer; the second active material layer is provided with a second groove, the first surface of the second single-sided hollow foil region is covered by the first active material layer, and the second surface of the second single-sided hollow foil region is exposed to the second groove; the first tab further comprises: a first tab, at least partially accommodated in the first groove, and bonded to the first single-sided hollow foil region through a first bonding layer, the first tab being electrically connected to the first conductive layer; a second tab, at least partially accommodated in the second groove, and bonded to the second single-sided hollow foil region through a second bonding layer, the second tab being electrically connected to the second conductive layer.

2. The electrode assembly of claim 1, wherein, The electrode assembly is in a wound structure; along the winding direction of the electrode assembly, the width of the first groove is W1, and along the winding axis direction of the electrode assembly, the length of the first groove is L1, satisfying 5mm≤W1≤15mm and 5mm≤L1≤25mm; and / or, along the winding direction of the electrode assembly, the width of the second groove is W2, and along the winding axis direction of the electrode assembly, the length of the second groove is L2, satisfying 5mm≤W2≤15mm and 5mm≤L2≤25mm.

3. The electrode assembly of claim 1, wherein, The electrode assembly is in a wound structure; the first tab comprises a first portion overlapping the first current collector, the thickness of the first portion is H1, the width of the first portion along the winding direction of the electrode assembly is W3, and the length of the first portion along the winding axis direction of the electrode assembly is L3, satisfying 2mm≤W3≤14mm, 2mm≤L3≤24mm, and 20μm≤H1≤120μm; and / or, the second tab comprises a second portion overlapping the first current collector, the thickness of the second portion is H2, the width of the second portion along the winding direction of the electrode assembly is W4, and the length of the second portion along the winding axis direction of the electrode assembly is L4, satisfying 2mm≤W4≤14mm, 2mm≤L4≤24mm, and 20μm≤H2≤120μm.

4. The electrode assembly of claim 1, wherein, The electrode assembly is in a wound structure; the first tab has a winding starting end and a winding ending end, and along the winding direction of the electrode assembly, the first groove is closer to the winding starting end than the second groove; Along the winding direction of the electrode assembly, the distance between the first groove and the winding start end is M1, the distance between the second groove and the winding end end is M2, and the length of the first electrode is M3, satisfying 0.25≤M1 / M3≤0.35 and 0.25≤M2 / M3≤0.

35.

5. The electrode assembly of claim 1, wherein, The first electrode tab has a plurality of first protrusions on the side facing the first current collector, and at least a portion of the plurality of first protrusions is in contact with the first conductive layer.

6. The electrode assembly of claim 1, wherein, The first electrode also includes: A first insulating element is disposed on the side of the first electrode tab away from the first current collector and covers the first electrode tab; The second insulating element is disposed on the side of the second electrode tab opposite to the first current collector and covers the second electrode tab.

7. The electrode assembly of claim 1, wherein, The second electrode includes: The second current collector has a third surface and a fourth surface disposed opposite to each other, and the second current collector includes a third single-sided empty foil area; A third active material layer is disposed on the third surface, and the third active material layer is provided with a third groove. The third surface of the third single-sided empty foil area is exposed in the third groove. A fourth active material layer is disposed on the fourth surface, and the fourth surface of the third single-sided empty foil area is covered by the fourth active material layer; The third electrode tab is at least partially housed in the third groove and is bonded to the third single-sided empty foil area through a third adhesive layer. The third electrode tab is electrically connected to the second current collector.

8. The electrode assembly of claim 7, wherein, The second current collector includes a third conductive layer, a second insulating layer and a fourth conductive layer distributed sequentially along its thickness direction. The third surface is the surface of the third conductive layer that faces away from the second insulating layer, and the fourth surface is the surface of the fourth conductive layer that faces away from the second insulating layer. The second current collector also includes a fourth single-sided empty foil area. The fourth active material layer is provided with a fourth groove, the third surface of the fourth single-sided empty foil area is covered by the third active material layer, and the fourth surface of the fourth single-sided empty foil area is exposed to the fourth groove; The second electrode also includes: The fourth tab is at least partially housed in the fourth groove and is bonded to the fourth single-sided empty foil area via a fourth adhesive layer. The third tab is electrically connected to the third conductive layer, and the fourth tab is electrically connected to the fourth conductive layer.

9. The electrode assembly of claim 8, wherein, At least one of the first adhesive layer, the second adhesive layer, the third adhesive layer, and the fourth adhesive layer is a conductive adhesive.

10. The electrode assembly of claim 8, wherein, The thicknesses of the first conductive layer, the second conductive layer, the third conductive layer, and the fourth conductive layer are all 0.2 μm to 3 μm.

11. The electrode assembly of claim 7, wherein, The second electrode also includes: A third insulating element is disposed on the side of the third electrode tab away from the second current collector and covers the third electrode tab.

12. The electrode assembly of claim 7, wherein, The first electrode also includes: A fourth insulating element is disposed on the first active material layer. When viewed along the thickness direction of the first current collector, the projection of the fourth insulating element covers the third electrode tab.

13. The electrode assembly of claim 7, wherein, The second electrode also includes: A fifth insulating element is disposed on the third active material layer. When viewed along the thickness direction of the second current collector, the projection of the fifth insulating element covers the first electrode tab. A sixth insulating element is disposed on the fourth active material layer. When viewed along the thickness direction of the second current collector, the projection of the sixth insulating element covers the second electrode tab.

14. The electrode assembly of claim 7, wherein, The electrode assembly has a wound structure; Along the winding direction of the electrode assembly, the width of the third groove is W5, and along the winding axis of the electrode assembly, the length of the third groove is L5, satisfying 5mm≤W5≤15mm, 5mm≤L5≤25mm; and / or, The third tab includes a third part connected to the third single-sided empty foil area. The thickness of the third part is H3 along the winding direction of the electrode assembly. The width of the third part is W6 along the winding axis of the electrode assembly. The length of the third part is L6, satisfying the following conditions: 2mm≤W6≤14mm, 2mm≤L6≤24mm, and 20μm≤H3≤120μm.

15. The electrode assembly of any one of claims 1-14, wherein, The first electrode is the positive electrode, and the second electrode is the negative electrode.

16. An electrochemical device, characterized by, Includes the electrode assembly as described in any one of claims 1-15.

17. An electrical device, characterized by Includes the electrochemical device as described in claim 16, wherein the electrochemical device is used to provide electrical energy.

Images