Electrode assembly, electrochemical device and electric equipment

Abstract

The embodiment of the invention provides an electrode assembly, an electrochemical device and electric equipment. The electrode assembly comprises a first pole piece and a second pole piece which are opposite in polarity. The first current collector comprises a first conducting layer, a first insulating layer and a second conducting layer which are sequentially distributed in the thickness direction of the first current collector. Wherein the first active material layer is provided with a first groove, the first surface of the first single-sided empty foil area is exposed out of 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 out of the second groove; the first tab is at least partially accommodated in the first groove and is bonded with the first single-sided empty foil area through a first bonding layer; and the second tab is at least partially accommodated in the second groove and is bonded with the second single-sided empty foil region through the second bonding layer, so that the safety risk of the traditional composite current collector can be effectively reduced.

Description

Technical Field

[0001] The present application relates to the technical field of electrochemical devices, and in particular to an electrode assembly, an electrochemical device and an electrical equipment. Background Art

[0002] With the development of electronic information technology, various electronic devices are also moving towards intelligence and multifunctionality, and the energy density requirements for electrochemical devices are becoming increasingly higher.

[0003] The existing composite current collector has a three-layer structure, with an insulating layer in the middle and conductive layers on both sides. Since the composite current collector contains an insulating layer in the middle, it cannot be directly welded to the tabs. It needs to be welded through the conductive layer and the tabs. The high-temperature molten insulating layer generated by welding realizes the conduction of the conductive layers on both sides. However, the conductive layer of the composite current collector is relatively thin and it is easy to form over-welding, and the welding point is prone to cracking, resulting in safety risks. In addition, the insulating layer also has the problem of insufficient melting during the melting process, so that the conductive layers on both sides are not electrically contacted, making the current carrying capacity of the pole piece weak. Summary of the invention

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

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

[0006] In a first aspect, the present application provides an electrode assembly, comprising a first pole piece and a second pole piece with opposite polarities, wherein the first pole piece comprises a first current collector, a first active material layer, a second active material layer, a first pole tab and a second pole tab. The first current collector comprises a first conductive layer, a first insulating layer and a second conductive layer sequentially distributed along its thickness direction, wherein 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. Among them, the first current collector includes a first single-sided empty foil area and a second single-sided empty foil area; the 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 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 in the second groove; the first pole ear is at least partially accommodated in the first groove, and is bonded to the first single-sided empty foil area through the first adhesive layer, and the first pole ear is electrically connected to the first conductive layer; the second pole ear is at least partially accommodated in the second groove, and is bonded to the second single-sided empty foil area through the second adhesive layer, and the second pole ear is electrically connected to the second conductive layer.

[0007] In the above scheme, the polarities of the first electrode sheet and the second electrode sheet are opposite, so that metal ions can move between the first electrode sheet and the second electrode sheet, 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 in sequence along its thickness direction, the first active material layer is arranged on the first surface of the first conductive layer, and the second active material layer is arranged on the second surface of the second conductive layer, so that metal ions can be embedded or de-embedded in the first active material layer and the second active material layer to realize 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 pole ear, the second surface of the first single-sided empty foil area is covered by the 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 pole ear. Compared with the case where grooves are provided on both the side of the current collector connected to the pole ear and the side away from the pole ear, in the present application, the first current collector is provided with the second active material layer on the side away from the first pole ear, and the first current collector is provided with the first active material layer on the side away from the second pole ear, which reduces the loss of active materials, so that the electrode assembly has more active material layers, which is convenient for 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, the first pole ear and the second pole ear are distributed on both sides of the first current collector, the first pole ear is electrically connected to the first conductive layer, and the second pole ear is electrically connected to the second conductive layer, so as to facilitate the extraction or import of electric energy, and the provision of the first pole ear and the second pole ear increases the number of pole ears and can also improve the charge and discharge rate. The first pole ear is at least partially accommodated in the first groove, and the second pole ear is at least partially accommodated in the second groove, which is convenient for connecting the first pole ear to the first current collector and the second pole ear to the first current collector, and can also make the overall thickness of the electrode assembly smaller, so that the energy density of the electrochemical device provided with this electrode assembly is larger. The first pole ear is bonded to the first conductive layer through the first adhesive layer, and the second pole ear is bonded to the second conductive layer through the second adhesive layer, which is convenient for operation and has low processing and manufacturing difficulty. By bonding the first pole ear to the first conductive layer through the first adhesive layer and the second pole ear to the second conductive layer through the second adhesive layer, there is no need to weld the pole ears, which reduces the safety risk of the first current collector caused by cracking of the weld mark.

[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 making the width W1 of the first groove satisfy 5mm≤W1≤15mm along the winding direction of the electrode assembly; and the length L1 of the first groove satisfy 5mm≤L1≤25mm along the winding axis direction of the electrode assembly, on the one hand, the first current collector and the first pole ear can have a larger connection area, and the first current collector and the first pole ear have a larger flow capacity; on the other hand, the volume loss of the first active material layer can be reduced, and the energy density of the electrochemical device provided with this electrode assembly is higher. By making the width W2 of the second groove satisfy 5mm≤W2≤15mm along the winding direction of the electrode assembly; and the length L2 of the second groove satisfy 5mm≤L2≤25mm along the winding axis direction of the electrode assembly, on the one hand, the first current collector and the second pole ear can have a larger connection area, and the first current collector and the second pole ear have a larger flow capacity; on the other hand, the volume loss of the second active material layer can be reduced, and the energy density of the electrochemical device provided with this electrode assembly is higher.

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

[0011] In the above scheme, by making the thickness H1 of the first part satisfy 20μm≤H1≤120μm; along the winding direction of the electrode assembly, the width W3 of the first part satisfies 2mm≤W3≤14mm; along the winding axis direction of the electrode assembly, the length L3 of the first part satisfies 2mm≤L3≤24mm. On the one hand, the first electrode ear and the first current collector have a larger connection area, and the first electrode ear and the first fluid have a larger 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 provided with this electrode assembly is higher. By making the thickness H2 of the second part satisfy 20μm≤H2≤120μm; along the winding direction of the electrode assembly, the width W4 of the second part satisfies 2mm≤W4≤14mm; along the winding axis direction of the electrode assembly, the length L4 of the second part satisfies 2mm≤L4≤24mm. On the one hand, the second electrode ear and the first current collector have a larger connection area, and the second electrode ear 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 provided with this electrode assembly is higher.

[0012] In one or more of the above optional embodiments, the electrode assembly is a winding structure; the first pole piece 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 starting end is M1, the distance between the second groove and the winding ending end is M2, and the length of the first pole piece is M3, satisfying 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 starting end of the winding be M1, the distance between the second groove and the ending end of the winding be M2, and the length of the first pole piece be M3, 0.25≤M1 / M3≤0.35, 0.25≤M2 / M3≤0.35 along the winding direction of the electrode assembly, on the one hand, it is convenient for processing and manufacturing, and reduces the risk of interference between the first groove and the second groove; on the other hand, it is convenient for the current to flow between the first current collector and the first pole ear and the second pole ear, and it is convenient for the output and input of electric energy, which is beneficial to improve the charging and discharging efficiency.

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

[0015] In the above scheme, the provision of multiple first protrusions can facilitate the positioning of the first pole ear to the first adhesive layer. The first adhesive layer can be accommodated in the area between two adjacent first protrusions to increase the bonding effect between the first pole ear and the first conductive layer. At least part of the multiple first protrusions is in contact with the first conductive layer to achieve electrical connection between the first pole ear and the first conductive layer.

[0016] In one or more of the above optional embodiments, the first pole piece also includes a first insulating member and a second insulating member, the first insulating member is arranged on the side of the first pole ear away from the first current collector and covers the first pole ear; the second insulating member is arranged on the side of the second pole ear away from the first current collector and covers the second pole ear.

[0017] In the above scheme, the first insulating member covers the first pole ear, so that the first insulating member can achieve the insulation effect of the first pole ear and the second pole piece, reducing the possibility of the first pole piece and the second pole piece contacting and short-circuiting; the second insulating member covers the second pole ear, so that the second insulating member can achieve the insulation effect of the second pole ear and the second pole piece, reducing the possibility of the first pole piece and the second pole piece contacting and short-circuiting. Since there are burrs on the surfaces of the first pole ear and the second pole ear, the first insulating member and the second insulating member can also isolate the burrs, so that the burrs are not easy to contact the second pole piece to cause a short circuit or damage the second pole piece.

[0018] In one or more of the above optional embodiments, the second pole piece includes a second current collector, a third active material layer, a fourth active material layer and a third pole ear, the second current collector has a third surface and a fourth surface arranged opposite to each other, and the second current collector includes a third single-sided empty foil area; the third active material layer is arranged on the third surface, the third active material layer is provided with a third groove, and the third surface of the third single-sided empty foil area is exposed to the third groove; the fourth active material layer is arranged 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 pole ear 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, and the third pole ear is electrically connected to the second current collector.

[0019] In the above scheme, the third active material layer is arranged on the third surface, and the fourth active material layer is arranged on the fourth surface, so that metal ions can be embedded or de-embedded in the third active material layer and the fourth active material layer to realize the movement of metal ions. The second current collector includes a third single-sided empty foil area, the third surface of the third single-sided empty foil area is bonded to the third pole ear, and the fourth surface of the third single-sided empty foil area is covered by the fourth active material layer. Compared with the case where grooves are arranged on both the side of the current collector connected to the pole ear and the side away from the pole ear, in the present application, the second current collector is provided with a fourth active material layer on the side away from the third pole ear, which reduces the loss of active materials, so that the electrode assembly has more active material layers, which is convenient for improving the energy density of the electrochemical device composed of the electrode assembly. The third pole ear is at least partially accommodated in the third groove, which is convenient for realizing the connection between the third pole ear and the second current collector, and can also make the overall thickness of the electrode assembly smaller, so that the energy density of the electrochemical device provided with this electrode assembly is larger. The third pole ear is bonded to the third single-sided empty foil area through the third adhesive layer, which is convenient for operation and has low difficulty in processing and manufacturing.

[0020] In one or more optional embodiments above, the second current collector includes a third conductive layer, a second insulating layer and a fourth conductive layer distributed in sequence along its thickness direction, the third surface is the surface of the third conductive layer facing away from the second insulating layer, the fourth surface is the surface of the fourth conductive layer facing away from the second insulating layer, and 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 pole piece also includes a fourth pole ear, the fourth pole ear is at least partially accommodated in the fourth groove, and is bonded to the fourth single-sided empty foil area through a fourth adhesive layer, the third pole ear is electrically connected to the third conductive layer, and the fourth pole ear is electrically connected to the fourth conductive layer.

[0021] In the above scheme, the second current collector is a composite current collector, the third pole ear and the fourth pole ear are distributed on both sides of the first current collector, the third pole ear is electrically connected to the third conductive layer, and the fourth pole ear is electrically connected to the fourth conductive layer, so as to facilitate the extraction or import of electric energy. The third pole ear and the fourth pole ear are arranged to increase the number of pole ears and improve the charge and discharge rate. The fourth pole ear is at least partially accommodated in the fourth groove, which is convenient for the connection between the fourth pole ear and the second current collector, and can also make the overall thickness of the electrode assembly smaller, so that the energy density of the electrochemical device provided with this electrode assembly is larger. The fourth pole ear is bonded to the fourth single-sided empty foil area through the fourth adhesive layer, which is convenient for operation and has low processing and manufacturing difficulty.

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

[0023] In the above solution, the third insulating member covers the third pole ear, so that the third insulating member can achieve the insulation effect between the third pole ear and the first pole piece, reducing the possibility of short circuit between the second pole piece and the first pole piece. Since there are burrs on the surface of the third pole ear, the third insulating member can also isolate the burrs, making it difficult for the burrs to contact the first pole piece to cause a short circuit or damage the first pole piece.

[0024] In one or more optional embodiments above, the first pole piece further includes a fourth insulating member, which is disposed on the first active material layer, and when observed along the thickness direction of the first current collector, the projection of the fourth insulating member covers the third pole lug.

[0025] In the above scheme, by making the projection of the fourth insulating member cover the third pole ear when observed along the thickness direction of the first current collector, the fourth insulating member can isolate the burrs of the third pole ear, making it difficult for the burrs to contact the first active material layer to cause a short circuit or damage the first pole piece.

[0026] In one or more of the above optional embodiments, the second pole piece also includes a fifth insulating member and a sixth insulating member, the fifth insulating member is arranged in the third active material layer, and when observed along the thickness direction of the second current collector, the projection of the fifth insulating member covers the first pole ear; the sixth insulating member is arranged in the fourth active material layer, and when observed along the thickness direction of the second current collector, the projection of the sixth insulating member covers the second pole ear.

[0027] In the above scheme, by making the projection of the fifth insulating member cover the first pole ear when viewed along the thickness direction of the second current collector, the fifth insulating member can isolate the burrs of the first pole ear, and further make it difficult for the burrs to contact the second active material layer to cause a short circuit or damage the second pole piece. By making the projection of the sixth insulating member cover the second pole ear when viewed along the thickness direction of the second current collector, the sixth insulating member can isolate the burrs of the second pole ear, and further make it difficult for the burrs to contact the second active material layer to cause a short circuit or damage the second pole piece.

[0028] In one or more optional embodiments above, 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 pole ear 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 making the width W5 of the third groove satisfy 5mm≤W5≤15mm along the winding direction of the electrode assembly; and the length L5 of the third groove satisfy 5mm≤L5≤25mm along the winding axis direction of the electrode assembly, on the one hand, the second current collector and the third electrode ear have a larger connection area, and the second current collector and the third electrode ear have a larger current 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 provided with this electrode assembly is higher. By making the thickness H3 of the third part satisfy 20μm≤H3≤120μm; along the winding direction of the electrode assembly, the width W6 of the third part satisfies 2mm≤W6≤14mm; along the winding axis direction of the electrode assembly, the length L6 of the third part satisfies 2mm≤L6≤24mm. On the one hand, the third electrode ear and the second current collector have a larger connection area, and the third electrode ear and the second fluid 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 provided with this electrode assembly is higher.

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

[0031] In the above solution, 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 achieve electrical connection between the tab and the current collector and increase the conductivity.

[0032] In one or more optional embodiments above, the thickness 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.

[0033] In the above scheme, the thickness of the conductive layer is greater than 0.2μm, so that the conductive layer can have good conductivity. The thickness is less than 3μm to ensure that the energy density of the battery will not be lost too much. Since there is an insulating layer in the middle of the composite current collector, it is necessary to use vapor deposition to set the conductive layer on the insulating layer, so the thickness cannot be too thick.

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

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

[0036] In a second aspect, the present application also provides an electrochemical device, comprising an electrode assembly provided according to any of the above embodiments.

[0037] In a third aspect, the present application further provides an electrical device, comprising an electrochemical device provided according to the above embodiment, wherein the electrochemical device is used to provide electrical energy.

[0038] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 A cross-sectional view of an electrode assembly provided in some embodiments of the present application;

[0041] Figure 2 A schematic diagram of the structure of a first pole piece provided in some embodiments of the present application;

[0042] Figure 3 A schematic diagram of assembling a plurality of first protrusions and a first conductive layer provided in some embodiments of the present application;

[0043] Figure 4 A cross-sectional view of an electrode assembly provided in some other embodiments of the present application;

[0044] Figure 5 A cross-sectional view of an electrode assembly provided in some other embodiments of the present application;

[0045] Figure 6 A schematic diagram of the structure of a second pole piece provided in some embodiments of the present application;

[0046] Figure 7 Cross-sectional views of electrode assemblies provided in some further embodiments of the present application.

[0047] Icons: 1-electrode assembly; 10-first pole piece; 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 pole ear; 141-first part; 142-first protrusion; 15-second pole ear; 151-second part; 161-first bonding layer; 162-second bonding layer; 171-first insulating member; 172-second insulating member; 173-fourth insulating member; 181-roll Winding starting end; 182-winding ending end; 20-second pole piece; 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 pole ear; 241-third part; 25-fourth pole ear; 251-fourth part; 261-third adhesive layer; 262-fourth adhesive layer; 271-third insulating member; 272-fifth insulating member; 273-sixth insulating member; 274-seventh insulating member. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0049] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

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

[0051] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0052] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0053] The term "multiple" as used in the present application refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple sheets" refers to more than two sheets (including two sheets).

[0054] The electrochemical device includes a housing, an electrode assembly and an electrolyte, and the housing is used to accommodate the electrode assembly and the electrolyte. The housing can be an aluminum shell, an aluminum plastic film, etc. The electrode assembly consists of a positive electrode sheet, a negative electrode sheet and a separator. The electrochemical device mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. The positive electrode sheet includes a positive electrode collector and a positive electrode active material layer, the positive electrode active material layer is coated on the surface of the positive electrode collector, and the part of the positive electrode collector not coated with the positive electrode active material layer is provided with a positive electrode ear, and the positive electrode ear is used to realize the input or output of the electric energy of the positive electrode sheet. Taking lithium-ion batteries as an example, the material of the positive electrode collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary material or lithium manganese oxide, etc. The negative electrode sheet includes a negative electrode collector and a negative electrode active material layer, the negative electrode active material layer is coated on the surface of the negative electrode collector, and the part of the negative electrode collector not coated with the negative electrode active material layer is provided with a negative electrode ear, and the electric energy input or output of the negative electrode sheet is realized through the negative electrode ear. The negative electrode current collector may be made of copper, and the negative electrode active material may be made of carbon material or silicon material, etc. The material of the separator may be polypropylene or polyethylene, etc. The separator is disposed between the positive electrode sheet and the negative electrode sheet to separate the positive electrode sheet from the negative electrode sheet, but allows metal ions to pass through.

[0055] With the development of the new energy industry, electrochemical devices are developing in the direction of high energy density and high power density. However, the positive electrode sheet or negative electrode sheet in the current electrode assembly is generally composed of a current collector, two layers or material layers respectively arranged on opposite sides of the current collector, and a pole ear. A groove needs to be provided on the active material layer to accommodate the pole ear so that the pole ear is connected to the current collector. However, due to process limitations, when the pole ear and the current collector are welded, two relative grooves need to be formed on the two layers of active material layers at the same time, and the pole ear is only accommodated in one of the grooves, which leads to waste of the groove on the side of the current collector away from the pole ear, resulting in loss of active material, and the energy density of the electrochemical device is low. In addition, the existing composite current collector has a three-layer structure, with an insulating layer in the middle layer and conductive layers on both sides. Since the composite current collector contains an insulating layer in the middle, it cannot be directly welded with the pole ear. It is necessary to weld through the conductive layer and the pole ear. The high-temperature molten insulating layer generated by welding realizes the conduction of the conductive layers on both sides, but the conductive layer of the composite current collector is thin and it is easy to form over-welding, and the welding point is easy to crack, resulting in safety risks. In addition, the insulating layer also has the problem of insufficient melting during the melting process, so that the conductive layers on both sides are not in electrical contact, resulting in a weak current carrying capacity of the pole piece.

[0056] In order to improve the safety performance of an electrochemical device, the present application provides an electrode assembly, which includes a first pole piece and a second pole piece with opposite polarities. The first pole piece includes a first current collector, a first active material layer, a second active material layer, a first pole ear and a second pole ear. 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 away from the first insulating layer, and the second conductive layer has a second surface away from the first insulating layer; the first active material layer is arranged on the first surface; and the second active material layer is arranged on the second surface. The first current collector includes a first single-sided empty foil area and a second single-sided empty foil area; the 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 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 in the second groove; the first pole ear is at least partially accommodated in the first groove, and is bonded to the first single-sided empty foil area through the first adhesive layer; the second pole ear is at least partially accommodated in the second groove, and is bonded to the second single-sided empty foil area through the second adhesive layer. The first pole ear is bonded to the first conductive layer through the first adhesive layer, and the second pole ear is bonded to the second conductive layer through the second adhesive layer, so there is no need to weld the pole ears, thereby reducing the safety risk of the first current collector caused by cracking of welding marks. In an electrode assembly of this structure, the polarities of the first electrode sheet and the second electrode sheet are opposite, so that metal ions can move between the first electrode sheet and the second electrode sheet, 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 in sequence along its thickness direction, the first active material layer is arranged on the first surface of the first conductive layer, and the second active material layer is arranged on the second surface of the second conductive layer, so that metal ions can be embedded or de-embedded in the first active material layer and the second active material layer to realize 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 pole ear, the second surface of the first single-sided empty foil area is covered by the 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 pole ear. Compared with the case where grooves are provided on both the side of the current collector connected to the pole ear and the side away from the pole ear, in the present application, the first current collector is provided with the second active material layer on the side away from the first pole ear, and the first current collector is provided with the first active material layer on the side away from the second pole ear, which reduces the loss of active materials, so that the electrode assembly has more active material layers, which is convenient for 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, the first pole ear and the second pole ear are distributed on both sides of the first current collector, the first pole ear is electrically connected to the first conductive layer, and the second pole ear is electrically connected to the second conductive layer, so as to facilitate the extraction or import of electric energy, and the provision of the first pole ear and the second pole ear increases the number of pole ears and can also improve the charge and discharge rate. The first pole ear is at least partially accommodated in the first groove, and the second pole ear is at least partially accommodated in the second groove, which is convenient for connecting the first pole ear to the first current collector and the second pole ear to the first current collector, and can also make the overall thickness of the electrode assembly smaller, so that the energy density of the electrochemical device provided with this electrode assembly is larger. The first pole ear is bonded to the first conductive layer through the first adhesive layer, and the second pole ear is bonded to the second conductive layer through the second adhesive layer, which is convenient for operation and has low processing and manufacturing difficulty. By bonding the first pole ear to the first conductive layer through the first adhesive layer and the second pole ear to the second conductive layer through the second adhesive layer, there is no need to weld the pole ears, which reduces the safety risk of the first current collector caused by cracking of the weld mark.

[0057] The present application provides an electrochemical device, including an electrode assembly, the electrochemical device may be a secondary battery or a primary battery, for example, a lithium ion battery, a sodium ion battery, or a magnesium ion battery, etc., which is not limited in the present application. The electrochemical device may be cylindrical, flat, rectangular, or in other shapes.

[0058] The embodiments of the present application provide an electrical device that uses an electrochemical device as a power source. The electrical device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, and the like.

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

[0060] The embodiment of the present application provides an electrode assembly 1, which includes a first electrode sheet 10 and a second electrode sheet 20 with opposite polarities, wherein the first electrode sheet 10 includes a first current collector 11, a first active material layer 12, a second active material layer 13, a first electrode tab 14, and a second electrode 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 the thickness direction thereof, wherein 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 exposed in the first active material layer 12 The second surface 115 of the second single-sided empty foil area 117 is exposed in the second groove 131; the first pole ear 14 is at least partially accommodated 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 pole ear 14 is electrically connected to the first conductive layer 111; the second pole ear 15 is at least partially accommodated 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 pole ear 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 surfaces of the first current collector 11 that are opposite to each other 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 section 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 section 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 material of the first conductive layer 111 and the material of the second conductive layer 113 can be the same. The material 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, for example, polypropylene, polyethylene terephthalate, etc.

[0064] In some embodiments, the first groove 121 is a recessed structure provided in 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. The first groove 121 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 to the first groove 121. Similarly, the second groove 131 is a recessed structure provided in 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. The second groove 131 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 to the second groove 131.

[0065] In some embodiments, the first electrode tab 14 and the second electrode tab 15 are made of metal 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 pole tab 14 is accommodated in the first groove 121, and the portion of the first pole tab 14 is bonded to the first surface 114 of the first single-sided empty foil area 116 through the first adhesive layer 161 to achieve the connection between the first pole tab 14 and the first conductive layer 111. The first pole tab 14 is electrically connected to the first conductive layer 111. For example, the first adhesive layer 161 may be an insulating material, and in the first groove 121, a portion of the first pole tab 14 may be bonded to the first surface 114 through the first adhesive layer 161, and a portion of the first pole tab 14 may contact the first surface 114 to achieve the electrical connection between the first pole tab 14 and the first conductive layer 111; or, the first adhesive layer 161 may include a conductive material, and the first pole tab 14 is bonded to the first surface 114 through the first adhesive layer 161, and the first pole tab 14 may be electrically connected to the first surface 114 through the conductive material in the first adhesive layer 161. For example, the first adhesive layer 161 is a conductive glue.

[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 pole tab 15 is accommodated in the second groove 131, and the portion of the second pole tab 15 is bonded to the second surface 115 of the second single-sided empty foil area 117 through the second adhesive layer 162 to achieve the connection between the second pole tab 15 and the second conductive layer 113. The second pole tab 15 is electrically connected to the second conductive layer 113. For example, the second adhesive layer 162 may be an insulating material, and in the second groove 131, a portion of the second pole tab 15 may be bonded to the second surface 115 through the second adhesive layer 162, and a portion of the second pole tab 15 may contact the second surface 115 to achieve the electrical connection between the second pole tab 15 and the second conductive layer 113; or, the second adhesive layer 162 may include a conductive material, and the second pole tab 15 is bonded to the second surface 115 through the second adhesive layer 162, and the second pole tab 15 may be electrically connected to the second surface 115 through the conductive material in the second adhesive layer 162. For example, the second adhesive layer 162 is a conductive glue.

[0070] In the above scheme, the polarities of the first electrode piece 10 and the second electrode piece 20 are opposite, so that metal ions can move between the first electrode piece 10 and the second electrode piece 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 in sequence along its thickness direction, the first active material layer 12 is arranged on the first surface 114 of the first conductive layer 111, and the second active material layer 13 is arranged on the second surface 115 of the second conductive layer 113, so that metal ions can be embedded or de-embedded in 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 pole ear 14, and the second surface 115 of the first single-sided empty foil area 116 is covered by the second active material layer 13. 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 bonded to the second pole ear 15. Compared with the case where grooves are provided on both the side of the current collector connected to the pole ear and the side away from the pole ear, in the present application, the first current collector 11 is provided with the second active material layer 13 on the side away from the first pole ear 14. 3. The first current collector 11 is provided with a first active material layer 12 on the side away from the second electrode tab 15, which reduces the loss of active material, so that the electrode assembly 1 has more active material layers, which is convenient for improving the energy density of the electrochemical device formed by the electrode assembly 1; at the same time, the first current collector 11 is a composite current collector, the first electrode tab 14 and the second electrode tab 15 are distributed on both sides of the first current collector 11, the first electrode tab 14 is electrically connected to the first conductive layer 111, and the second electrode tab 15 is electrically connected to the second conductive layer 113, so as to facilitate the extraction or import of electric energy. The arrangement of the first electrode tab 14 and the second electrode tab 15 increases the number of electrodes and can also improve the charge and discharge rate. The first electrode tab 14 is at least partially accommodated in the first groove 121, and the second electrode tab 15 is at least partially accommodated in the second groove 131, which is convenient for realizing the connection between the first electrode tab 14 and the first current collector 11, and the connection between the second electrode tab 15 and the first current collector 11, and can also make the overall thickness of the electrode assembly 1 smaller, so that the energy density of the electrochemical device provided with the electrode assembly 1 is larger. The first pole tab 14 is bonded to the first conductive layer 111 through the first adhesive layer 161, and the second pole tab 15 is bonded to the second conductive layer 113 through the second adhesive layer 162, which is convenient for operation and has low difficulty in processing and manufacturing. The first pole tab 14 is bonded to the first conductive layer 111 through the first adhesive layer 161, and the second pole tab 15 is bonded to the second conductive layer 113 through the second adhesive layer 162, without welding the pole tabs, thereby reducing the safety risk of the first current collector 11 caused by cracking due to welding marks.

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

[0072] Please refer to Figure 1 , and further refer to Figure 2 , Figure 2 A schematic diagram of the structure of the first pole piece provided in some embodiments of the present 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 direction of the electrode assembly 1 , the length L1 of the first groove 121 satisfies 5 mm ≤ L1 ≤ 25 mm. For example, L1 may be 5 mm, 10 mm, 15 mm, 20 mm or 25 mm.

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

[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 direction of the electrode assembly 1 , the length L2 of the second groove 131 satisfies 5 mm≤L2≤25 mm. For example, L2 may be 5 mm, 10 mm, 15 mm, 20 mm or 25 mm.

[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 direction of the electrode assembly 1 satisfies 5mm≤L2≤25mm, on the one hand, the first current collector 11 and the second electrode tab 15 can have a larger connection area, and the first current collector 11 and the second electrode tab 15 can have a larger current 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 provided with this electrode assembly 1 can be higher.

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

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

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

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

[0083] Along the winding axis direction of the 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 making the thickness H1 of the first part 141 satisfy 20μm≤H1≤120μm; along the winding direction of the electrode assembly 1, the width W3 of the first part 141 satisfies 2mm≤W3≤14mm; along the winding axis direction of the electrode assembly 1, the length L3 of the first part 141 satisfies 2mm≤L3≤24mm. On the one hand, the first electrode tab 14 and the first current collector 11 have a larger connection area, and the first electrode 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 provided with this electrode assembly 1 is higher.

[0085] In some embodiments, the second electrode tab 15 includes a second portion 151 overlapping the first current collector 11 , and when viewed along the thickness direction of the first current collector 11 , the second portion 151 is located in the second groove 131 , and the second portion 151 overlaps the second current collector.

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

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

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

[0089] Along the winding axis direction of the 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 making the thickness H2 of the second part 151 satisfy 20μm≤H2≤120μm; along the winding direction of the electrode assembly 1, the width W4 of the second part 151 satisfies 2mm≤W4≤14mm; along the winding axis direction of the electrode assembly 1, the length L4 of the second part 151 satisfies 2mm≤L4≤24mm. On the one hand, the second electrode tab 15 and the first current collector 11 have a larger connection area, and the second electrode 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 provided with this electrode assembly 1 is higher.

[0091] In some embodiments, the electrode assembly 1 is a wound structure; the first pole piece 10 has a winding starting end 181 and a winding ending end 182, and the first pole piece 10 is a continuous strip structure. Along the winding method of the electrode assembly 1, the winding starting end 181 refers to the end of the first pole piece 10 closest to the winding axis of the electrode assembly 1, and the winding ending end 182 refers to the end of the first pole piece 10 farthest 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 starting 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 starting end 181 is M1, the distance between the second groove 131 and the winding ending end 182 is M2, and the length of the first pole piece 10 is M3, satisfying 0.25≤M1 / M3≤0.35; 0.25≤M2 / M3≤0.35.

[0093] It should be pointed out that for the convenience of description, Figure 1The first pole piece 10 is a schematic diagram of the unfolded state, M1 is the distance between one end of the first groove 121 close to the winding starting end 181 and the winding starting end 181, M2 is the distance between one end of the second groove 131 close to the winding ending end 182 and the winding ending end 182, and M3 is the length of the first pole piece 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, the distance between the first groove 121 and the winding start end 181 is small, the distance between the second groove 131 and the winding end 182 is small, and the distance between the first groove 121 and the second groove 131 is large. The flow path of the current in the middle of the winding direction toward the first pole ear and the second pole ear is long, and the current extraction capability is poor.

[0095] By making the distance between the first groove 121 and the starting end of the winding be M1, the distance between the second groove 131 and the ending end of the winding be M2, and the length of the first pole piece 10 be M3 along the winding direction of the electrode assembly 1, satisfying 0.25≤M1 / M3≤0.35 and 0.25≤M2 / M3≤0.35, on the one hand, it is convenient for processing and manufacturing and reduces the risk of interference between the first groove and the second groove; on the other hand, it is convenient for the current to flow between the first current collector and the first pole ear and the second pole ear, and it is convenient for the output and input of electric energy, which is beneficial to improve the charging and discharging efficiency.

[0096] Please refer to Figure 3 , Figure 3 A schematic diagram of assembling a plurality of first protrusions and a first conductive layer provided in some embodiments of the present application, Figure 3 In some embodiments, a plurality of first protrusions 142 are formed on a 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 pole lug 14 and the first current collector 11, the first pole lug 14 has a fifth surface facing the first current collector 11, and a first protrusion 142 is formed on the side of the first pole lug 14 facing the first current collector 11, and the first protrusion 142 protrudes toward the first current collector 11, so that the first pole lug 14 contacts the first conductive layer 111 through the first protrusion 142, thereby realizing the electrical connection between the first pole lug 14 and the first current collector 11.

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

[0099] In some embodiments, the first tab 14 can be processed by stamping, laser, cold heading, etching, etc. to form the first protrusion 142 .

[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 the first pole tab 14 is assembled with the first conductive layer 111, the first adhesive layer 161 can be first coated on the fifth surface of the first pole tab 14, and then the first pole tab 14 coated with the first adhesive layer 161 is attached to the first conductive layer 111, and the first adhesive layer 161 is activated by hot pressing to complete the bonding and fixing between the first pole tab 14 and the first current collector 11. A plurality of first protrusions 142 are arranged at intervals, and the area between adjacent first protrusions 142 can accommodate the first adhesive, the first protrusion 142 is in contact with the first conductive layer 111, and the first adhesive is bonded to the fifth surface and the first surface 114, so that the first pole tab 14 is bonded to the first current collector 11, and the first pole tab 14 is electrically connected to the first conductive layer 111.

[0102] By forming a plurality of first protrusions 142 on the side of the first pole tab 14 facing the first current collector 11, it is possible to facilitate positioning of the first pole tab 14 on 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 pole tab 14 and the first conductive layer 111. At least part of the plurality of first protrusions 142 is in contact with the first conductive layer 111, so as to achieve electrical connection between the first pole tab 14 and the first conductive layer 111.

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

[0104] The arrangement form of the second protrusion may refer to the arrangement form of the first protrusion 142 .

[0105] By forming a plurality of second protrusions on the side of the second pole tab 15 facing the first current collector 11, it is possible to facilitate positioning of the second pole tab 15 on 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 pole tab 15 and the second conductive layer 113. At least part of the plurality of second protrusions is in contact with the second conductive layer 113 to achieve electrical connection between the second pole tab 15 and the second conductive layer 113.

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

[0107] In some embodiments, the first insulating member 171 may be a tape, which has a simple structure and facilitates the positioning of the first insulating member 171 .

[0108] In some embodiments, the first insulating member 171 may be in a sheet shape, and a thickness direction of the first insulating member 171 is parallel to a 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, it is convenient to assemble and position the first insulating member 171 . On the other hand, the first insulating member 171 can cover the first electrode tab 14 .

[0110] The first insulating member 171 covers the first pole ear 14, so that the first insulating member 171 can achieve the insulation effect between the first pole ear 14 and the second pole piece 20, reducing the possibility of short circuit between the first pole piece 10 and the second pole piece 20. Since there are burrs on the surface of the first pole ear 14, the first insulating member 171 can also isolate the burrs, so that the burrs are not easy to contact with the second pole piece 20 to cause a short circuit or damage the second pole piece 20.

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

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

[0113] In some embodiments, the second insulating member 172 may be in a sheet shape, and a thickness direction of the second insulating member 172 is parallel to a 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 , and when observed along the thickness direction of the first current collector 11 , the second insulating member 172 covers the second groove 131 . On the one hand, it is convenient to assemble and position the second insulating member 172 ; on the other hand, the second insulating member 172 can cover the second electrode tab 15 .

[0115] The second insulating member 172 covers the second pole ear 15, so that the second insulating member 172 can achieve the insulation effect of the second pole ear 15 and the second pole piece 20, reducing the possibility of short circuit between the first pole piece 10 and the second pole piece 20. Since there are burrs on the surface of the second pole ear 15, the second insulating member 172 can also isolate the burrs, so that the burrs are not easy to contact with the second pole piece 20 to cause a short circuit or damage the second pole piece 20.

[0116] Please refer to Figure 1 and Figure 4 , Figure 4 A cross-sectional view of an electrode assembly provided in some other embodiments of the present application, Figure 4 It is a cross-sectional view of the electrode assembly in the unfolded state. In some embodiments, the second electrode sheet 20 includes a second current collector 21, a third active material layer 22, a fourth active material layer 23 and a third pole tab 24. The second current collector 21 has a third surface 211 and a fourth surface 212 arranged opposite to each other. The second current collector 21 includes a third single-sided empty foil area 213; the third active material layer 22 is arranged on the third surface 211, and the third active material layer 22 is provided with 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 arranged 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 pole tab 24 is at least partially accommodated in the third groove 221, and is bonded to the third single-sided empty foil area 213 through the third bonding layer 261. The third pole tab 24 is electrically connected to the third single-sided empty foil area 213.

[0117] In some embodiments, the third surface 211 and the fourth surface 212 are two opposite 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 area 213 is a section of the second current collector 21 , and has a third surface 211 and a fourth surface 212 .

[0119] In some embodiments, the second current collector 21 may be made of aluminum, copper, or the like.

[0120] In some embodiments, the third groove 221 is a recessed structure disposed in 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 to 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 pole tab 24 is accommodated in the third groove 221, and the portion of the third pole tab 24 is bonded to the third surface 211 of the third single-sided empty foil area 213 through the third adhesive layer 261 to achieve the connection between the third pole tab 24 and the second current collector 21. For example, the third adhesive layer 261 may be an insulating material, and in the third groove 221, a portion of the third pole tab 24 may be bonded to the third surface 211 through the third adhesive layer 261, and a portion of the third pole tab 24 may contact the third surface 211 to achieve the electrical connection between the third pole tab 24 and the second current collector 21; or, the third adhesive layer 261 may include a conductive material, and the third pole tab 24 is bonded to the third surface 211 through the third adhesive layer 261, and the third pole tab 24 may be electrically connected to the third surface 211 through the conductive material in the third adhesive layer 261. For example, the third adhesive layer 261 is a conductive glue.

[0123] In some embodiments, please refer to Figure 1 , the third surface 211 may 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 may be a surface of the second current collector 21 facing away from the first active material layer 12 .

[0124] In the above scheme, the third active material layer 22 is arranged on the third surface 211, and the fourth active material layer 23 is arranged on the fourth surface 212, so that metal ions can be embedded or de-embedded in 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 pole ear 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 arranged on both the side of the current collector connected to the pole ear and the side away from the pole ear, in the present application, the second current collector 21 is provided with the fourth active material layer 23 on the side away from the third pole ear 24, which reduces the loss of active materials, so that the electrode assembly 1 has more active material layers, which is convenient for improving the energy density of the electrochemical device constituted by the electrode assembly 1. The third pole tab 24 is at least partially accommodated in the third groove 221, which is convenient for connecting the third pole tab 24 with the second current collector 21, and can also reduce the overall thickness of the electrode assembly 1, so that the energy density of the electrochemical device provided with the electrode assembly 1 is relatively high. The third pole tab 24 is bonded to the third single-sided empty foil area 213 through the third bonding layer 261, which is convenient for operation and has low processing and manufacturing difficulty.

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

[0126] In some embodiments, the third insulating member 271 may 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 in a sheet shape, and a thickness direction of the third insulating member 271 is parallel to a 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 observed along the thickness direction of the second current collector 21, the third insulating member 271 covers the third groove 221. On the one hand, it is convenient to assemble and position the third insulating member 271. On the other hand, the third insulating member 271 can cover the third pole ear 24.

[0129] The third insulating member 271 covers the third pole ear 24, so that the third insulating member 271 can achieve the insulation effect between the third pole ear 24 and the first pole piece 10, reducing the possibility of short circuit between the second pole piece 20 and the first pole piece 10. Since there are burrs on the surface of the third pole ear 24, the third insulating member 271 can also isolate the burrs, so that the burrs are not easy to contact with the first pole piece 10 to cause a short circuit or damage the first pole piece 10.

[0130] Please refer to Figure 5 , Figure 5 A cross-sectional view of an electrode assembly provided in some other embodiments of the present application, Figure 5 In some embodiments, the first pole piece 10 further includes a fourth insulating member 173 , which is disposed on the first active material layer 12 , and when viewed along the thickness direction of the first current collector 11 , the projection of the fourth insulating member 173 covers the third pole tab 24 .

[0131] In some embodiments, the fourth insulating member 173 may be an adhesive tape, and the fourth insulating member 173 may be bonded to the first active material layer 12 , which has a simple structure and facilitates positioning of the fourth insulating member 173 .

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

[0133] In some embodiments, when observed along the thickness direction of the first current collector 11, the fourth insulating member 173 is arranged corresponding to the third pole piece 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 relatively small, so that the energy density of the electrochemical device provided with this electrode assembly 1 can be relatively large. For another example, the projection of the fourth insulating member 173 can cover the third groove 221. When observed along the thickness direction of the first current collector 11, the fourth insulating member 173 and the second pole piece 20 have a relatively large overlapping area.

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

[0135] Please refer to Figure 5 In some embodiments, the second pole piece 20 further includes a fifth insulating member 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 member 272 covers the first pole tab 14 .

[0136] In some embodiments, the fifth insulating member 272 may be an adhesive tape, and the fifth insulating member 272 may be bonded to the third active material layer 22 . The structure is simple, and the positioning of the fifth insulating member 272 is facilitated.

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

[0138] In some embodiments, when observed along the thickness direction of the second current collector 21, the fifth insulating member 272 is arranged corresponding to the first pole ear 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 relatively small, so that the energy density of the electrochemical device provided with this electrode assembly 1 can be relatively large. For another example, the projection of the fifth insulating member 272 can cover the first groove 121. When observed along the thickness direction of the second current collector 21, the fifth insulating member 272 and the first pole piece 10 have a relatively large overlapping area.

[0139] By making the projection of the fifth insulating member 272 cover the first pole ear 14 when observed along the thickness direction of the second current collector 21 , the fifth insulating member 272 can isolate the burrs of the first pole ear 14 , further making it difficult for the burrs to contact the second active material layer 13 to cause a short circuit or damage the second pole piece 20 .

[0140] In some embodiments, the second pole piece 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 pole tab 15 .

[0141] In some embodiments, the sixth insulating member 273 may be an adhesive tape, and the sixth insulating member 273 may be bonded to the fourth active material layer 23 , which has a simple structure and facilitates the positioning of the sixth insulating member 273 .

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

[0143] In some embodiments, when observed along the thickness direction of the second current collector 21, the sixth insulating member 273 is arranged corresponding to the second pole piece 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 relatively small, so that the energy density of the electrochemical device provided with this electrode assembly 1 can be relatively large. For another example, the projection of the sixth insulating member 273 can cover the second groove 131. When observed along the thickness direction of the second current collector 21, the sixth insulating member 273 and the first pole piece 10 have a relatively large overlapping area.

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

[0145] Please refer to Figure 1 and Figure 4 , and further refer to Figure 6 , Figure 6 A schematic diagram of the structure of the second pole piece provided in some embodiments of the present 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.

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

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

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

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

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

[0153] Along the winding axis direction of the 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 making the thickness H3 of the third part 241 satisfy 20μm≤H3≤120μm; along the winding direction of the electrode assembly 1, the width W6 of the third part 241 satisfies 2mm≤W6≤14mm; along the winding axis direction of the electrode assembly 1, the length L6 of the third part 241 satisfies 2mm≤L6≤24mm. On the one hand, the third pole ear 24 and the second current collector 21 have a larger connection area, and the third pole ear 24 and the second fluid 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 provided 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 other embodiments of the present application, Figure 7 It is a cross-sectional view of the electrode assembly in the 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 distributed in sequence along its thickness direction, the third surface 211 is the surface of the third conductive layer 214 away from the second insulating layer 215, the fourth surface 212 is the surface of the fourth conductive layer 216 away from the second insulating layer 215, and the second current collector 21 also includes a fourth single-sided empty foil area 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 area 217 is covered by the third active material layer 22, and the fourth surface 212 of the fourth single-sided empty foil area 217 is exposed in the fourth groove 231; the second pole piece 20 also includes a fourth pole ear 25, the fourth pole ear 25 is at least partially accommodated in the fourth groove 231, and is bonded to the fourth single-sided empty foil area 217 through a fourth adhesive layer 262, the third pole ear 24 is electrically connected to the third conductive layer 214, and the fourth pole ear 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 material of the third conductive layer 214 and the material of the fourth conductive layer 216 can be the same. The material of the third conductive layer 214 and the material of the fourth conductive layer 216 can be aluminum, copper, etc. The second insulating layer 215 can be a polymer layer, for example, 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 away from the first active material layer 12; or, the third surface 211 may be the surface of the second current collector 21 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 area 217 is a section of the second current collector 21 and has a third surface 211 and a fourth surface 212 .

[0159] In some embodiments, the fourth groove 231 is a recessed structure arranged in 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 facing 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 to 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 pole tab 25 is accommodated in the fourth groove 231, and the portion of the fourth pole tab 25 is bonded to the fourth surface 212 of the fourth single-sided empty foil area 217 through the fourth adhesive layer 262 to achieve the connection between the fourth pole tab 25 and the second current collector 21. The fourth pole tab 25 is electrically connected to the second current collector 21. For example, the fourth adhesive layer 262 may be an insulating material. In the fourth groove 231, a portion of the fourth pole tab 25 may be bonded to the fourth surface 212 through the fourth adhesive layer 262, and a portion of the fourth pole tab 25 may contact the fourth surface 212 to achieve the electrical connection between the fourth pole tab 25 and the second current collector 21. Alternatively, the fourth adhesive layer 262 may include a conductive material, the fourth pole tab 25 is bonded to the fourth surface 212 through the fourth adhesive layer 262, and the fourth pole tab 25 may be electrically connected to the fourth surface 212 through the conductive material in the fourth adhesive layer 262. For example, the fourth adhesive layer 262 is a conductive glue.

[0162] In the above scheme, the second current collector 21 is a composite current collector, the third pole ear 24 and the fourth pole ear 25 are distributed on both sides of the first current collector 11, the third pole ear 24 is electrically connected to the third conductive layer 214, and the fourth pole ear 25 is electrically connected to the fourth conductive layer 216, so as to facilitate the extraction or import of electric energy. The third pole ear 24 and the fourth pole ear 25 are arranged to increase the number of pole ears and improve the charge and discharge rate. The fourth pole ear 25 is at least partially accommodated in the fourth groove 231, which is convenient for realizing the connection between the fourth pole ear 25 and the second current collector 21, and can also make the overall thickness of the electrode assembly 1 smaller, so that the energy density of the electrochemical device provided with this electrode assembly 1 is larger. The fourth pole ear 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 difficulty in processing and manufacturing.

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

[0164] The seventh insulating member 274 covers the fourth pole tab 25, so that the seventh insulating member 274 can achieve the insulation effect of the fourth pole tab 25 and the first pole piece 10, reducing the possibility of short circuit between the second pole piece 20 and the first pole piece 10. Since there are burrs on the surface of the fourth pole tab 25, the seventh insulating member 274 can also isolate the burrs, so that the burrs are not easy to contact with the first pole piece 10 to cause a short circuit or damage the first pole piece 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, satisfying 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, along the winding axis direction of the electrode assembly 1, the length of the fourth groove 231 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 satisfies 5mm≤W7≤15mm along the winding direction of the electrode assembly 1 and the length L7 of the fourth groove 231 satisfies 5mm≤L7≤25mm along the winding axis direction of the electrode assembly 1, on the one hand, the second current collector 21 and the fourth pole tab 25 have a larger connection area, and the second current collector 21 and the fourth pole tab 25 have a larger current flow capacity; on the other hand, the volume loss of the fourth active material layer 23 can be reduced, and the energy density of the electrochemical device provided with this electrode assembly 1 is higher.

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

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

[0170] The thickness of the fourth portion 251 is H8, satisfying 20 μm≤H8≤120 μm. For example, H8 may be 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm or 120 μm.

[0171] Along the winding direction of the electrode assembly 1, the width of the fourth portion 251 is W8, satisfying 2mm≤W8≤14mm. For example, W8 may be 2mm, 4mm, 6mm, 8mm, 10mm, 12mm or 14mm.

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

[0173] By making the thickness H8 of the fourth portion 251 satisfy 20μm≤H8≤120μm; along the winding direction of the electrode assembly 1, the width W8 of the fourth portion 251 satisfies 2mm≤W8≤14mm; along the winding axis direction of the electrode assembly 1, the length L8 of the fourth portion 251 satisfies 2mm≤L8≤24mm. On the one hand, the fourth pole tab 25 and the second current collector 21 have a larger connection area, and the fourth pole tab 25 and the second fluid 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 provided with this electrode assembly 1 is higher.

[0174] In some embodiments, the thickness of the first conductive layer 111, the second conductive layer 113, the third conductive layer 214, and the fourth conductive layer 216 are all 0.2 μm to 3 μm. The thickness of the conductive layer is greater than 0.2 μm, so that the conductive layer can have good conductivity. The thickness is less than 3 μm to ensure that the energy density of the battery will not be lost too much. Since there is an insulating layer in the middle of the composite current collector, it is necessary to use a vapor deposition method to set the conductive layer on the insulating layer, so the thickness cannot be too thick.

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

[0176] The first electrode sheet 10 is a positive electrode sheet, and the first electrode tab 14 and the second electrode tab 15 are positive electrode tabs. Compared with a single positive electrode tab, the two positive electrode tab structures of the present 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 1The embodiment of the present application provides an electrode assembly 1, comprising a first pole piece 10 and a second pole piece 20 with opposite polarities, wherein the first pole piece 10 comprises a first current collector 11, a first active material layer 12, a second active material layer 13, a first pole ear 14, a second pole ear 15, a first insulating member 171 and a second insulating member 172. The first current collector 11 comprises a first conductive layer 111, a first insulating layer 112 and a second conductive layer 113 sequentially distributed along the thickness direction thereof, wherein 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. Among them, 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 pole ear 14 is at least partially accommodated in the first groove 121, and is bonded to the first single-sided empty foil area 116 through the first adhesive layer 161; the second pole ear 15 is at least partially accommodated in the second groove 131, and is bonded to the second single-sided empty foil area 117 through the second adhesive layer 162. The first insulating member 171 is disposed on a side of the first electrode tab 14 away from the first current collector 11 and covers the first electrode tab 14. The second insulating member 172 is disposed on a side of the second electrode tab 15 away from the first current collector 11 and covers the second electrode tab 15.

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

[0179] The present application also provides an electrochemical device, comprising an electrode assembly 1 provided according to any of the above embodiments.

[0180] The present application also provides an electrical device, including the electrochemical device provided according to the above embodiment, and the electrochemical device is used to provide electrical energy.

[0181] The electrical equipment may be any of the aforementioned equipment or systems using electrochemical devices.

[0182] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present 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 in that: It includes a first pole piece and a second pole piece with opposite polarities, wherein the first pole piece includes: A first current collector comprises a first conductive layer, a first insulating layer and a second conductive layer sequentially distributed along a thickness direction thereof, wherein 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; A first active material layer, disposed on the first surface; A second active material layer is disposed on the second surface; Wherein, the first current collector comprises a first single-sided empty foil area and a second single-sided empty foil area; 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 pole piece further comprises: A first electrode tab is at least partially accommodated in the first groove and is bonded to the first single-sided empty foil area via a first bonding layer, and the first electrode tab is electrically connected to the first conductive layer; The second pole tab is at least partially accommodated in the second groove and is bonded to the second single-sided empty foil area via a second bonding layer. The second pole tab is electrically connected to the second conductive layer.

2. The electrode assembly according to claim 1, characterized in that: 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.

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

4. The electrode assembly according to claim 1, characterized in that: The electrode assembly is a wound structure; The first pole piece 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 starting end of the winding is M1, the distance between the second groove and the ending end of the winding is M2, and the length of the first pole piece is M3, satisfying 0.25≤M1 / M3≤0.35, 0.25≤M2 / M3≤0.

35.

5. The electrode assembly according to claim 1, characterized in that: A plurality of first protrusions are formed on a side of the first electrode tab facing the first current collector, and at least part of the plurality of first protrusions are in contact with the first conductive layer.

6. The electrode assembly according to claim 1, characterized in that: The first pole piece further comprises: A first insulating member is disposed on a 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 a side of the second pole tab away from the first current collector and covers the second pole tab.

7. The electrode assembly according to claim 1, characterized in that: The second pole piece comprises: A second current collector having a third surface and a fourth surface disposed opposite to each other, wherein the second current collector comprises a third single-sided empty foil area; A third active material layer is disposed on the third surface, the third active material layer is provided with a third groove, and the third surface of the third single-sided empty foil area is exposed in the third groove; a fourth active material layer, disposed on the fourth surface, the fourth surface of the third single-sided empty foil area being covered by the fourth active material layer; The third pole tab is at least partially accommodated in the third groove and is bonded to the third single-sided empty foil area via a third bonding layer. The third pole tab is electrically connected to the second current collector.

8. The electrode assembly according to claim 7, characterized in that: The second current collector comprises a third conductive layer, a second insulating layer and a fourth conductive layer sequentially distributed along the thickness direction thereof, the third surface is a surface of the third conductive layer away from the second insulating layer, the fourth surface is a surface of the fourth conductive layer away from the second insulating layer, and the second current collector further comprises 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 in the fourth groove; The second pole piece further comprises: The fourth pole tab is at least partially accommodated in the fourth groove and is bonded to the fourth single-sided empty foil area through a fourth bonding layer. The third pole tab is electrically connected to the third conductive layer, and the fourth pole tab is electrically connected to the fourth conductive layer.

9. The electrode assembly according to claim 8, characterized in that: At least one of the first adhesive layer, the second adhesive layer, the third adhesive layer, and the fourth adhesive layer is conductive glue.

10. The electrode assembly according to claim 8, characterized in that: The thickness 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 according to claim 7, characterized in that: The second pole piece further comprises: The third insulating member is disposed on a side of the third pole tab away from the second current collector and covers the third pole tab.

12. The electrode assembly according to claim 7, characterized in that: The first pole piece further comprises: A fourth insulating member is disposed on the first active material layer, and when viewed along the thickness direction of the first current collector, a projection of the fourth insulating member covers the third electrode tab.

13. The electrode assembly according to claim 7, characterized in that: The second pole piece further comprises: a fifth insulating member, disposed on the third active material layer, wherein a projection of the fifth insulating member covers the first electrode tab when viewed along the thickness direction of the second current collector; A sixth insulating member is disposed on the fourth active material layer, and when viewed along the thickness direction of the second current collector, a projection of the sixth insulating member covers the second electrode tab.

14. The electrode assembly according to claim 7, characterized in that: 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 electrode tab includes a third portion connected to the third single-sided empty foil area, the thickness of the third portion is H3, along the winding direction of the electrode assembly, the width of the third portion is W6, along the winding axis direction of the electrode assembly, the length of the third portion is L6, satisfying 2mm≤W6≤14mm, 2mm≤L6≤24mm, 20μm≤H3≤120μm.

15. The electrode assembly according to any one of claims 1 to 14, characterized in that: The first pole piece is a positive pole piece, and the second pole piece is a negative pole piece.

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

17. An electrical equipment, characterized in that: Comprising the electrochemical device of claim 16, the electrochemical device is used to provide electrical energy.

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