Pole piece, electrochemical device and pole piece manufacturing method

Abstract

The invention discloses a pole piece, an electrochemical device and a pole piece manufacturing method, and relates to the technical field of electrochemical energy storage. The pole piece comprises an active material layer, a current collector and a tab, at least one side of the current collector is coated with the active material layer, the current collector is further provided with an empty foil area, the current collector in the empty foil area is not coated with the active material layer, and the current collector is provided with a first via hole in the empty foil area; the tab is fixed in the empty foil area and connected with the current collector, the tab is provided with a second via hole, and the second via hole is communicated with the first via hole; and the pole piece further comprises a conductive piece, a part of the conductive piece is arranged in the first conduction hole, and the rest part of the conductive piece is arranged in the second conduction hole, so that the tab and the current collector are electrically conducted. According to the pole piece, current can be transmitted through a plurality of dispersed conduction paths, the contact resistance between the tab and the current collector is reduced, and the structural connection strength between the tab and the current collector is enhanced.

Description

Technical Field

[0001] This application relates to the field of electrochemical energy storage technology, and in particular to an electrode, an electrochemical device, and a method for manufacturing the electrode. Background Technology

[0002] In the manufacturing of electrochemical energy storage devices such as lithium-ion batteries, the battery cell, as the core unit for energy storage and release, has its structural design and manufacturing process directly determining the battery's energy density, cycle life, safety, and production efficiency. A battery cell is made by stacking or winding electrode sheets, which include a current collector, an active material layer, and tabs connected to the empty foil area of ​​the current collector.

[0003] In traditional technology, the tab and the current collector are fixed by welding. However, welding is prone to problems such as incomplete welding or weak welds, resulting in a large internal resistance between the tab and the current collector. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes an electrode that enables current to be transmitted through multiple distributed conduction paths, reducing the contact resistance between the electrode and the current collector, and strengthening the structural connection between the electrode and the current collector.

[0005] This application also proposes an electrochemical device having the above-mentioned electrodes.

[0006] This application also proposes a method for manufacturing electrode sheets.

[0007] This application also proposes another method for manufacturing electrodes.

[0008] The electrode sheet according to the first aspect embodiment of this application includes: Active material layer; A current collector, wherein at least one side of the current collector is coated with the active material layer, and the current collector is further provided with an empty foil area, wherein the current collector in the empty foil area is not coated with the active material layer, and the current collector has a first through hole in the empty foil area; The electrode tab is fixed to the empty foil area and connected to the current collector. The electrode tab has a second through hole, which communicates with the first through hole. The electrode further includes a conductive element, part of which is disposed in the first through hole and the remaining part is disposed in the second through hole, so that the electrode tab and the current collector are electrically connected.

[0009] The electrode sheet according to the embodiments of this application has at least the following beneficial effects: By setting a first and second through-hole connecting the current collector and the tab, and embedding conductive elements therein, current can be transmitted through multiple dispersed conductive paths. This reduces the contact resistance between the tab and the current collector, avoiding poor conductivity caused by incomplete soldering or over-soldering, and improving the battery's stability under high-rate charge and discharge. Furthermore, since the two ends of the conductive element are embedded in the through-holes of the current collector and the tab respectively, the structural connection strength between the tab and the current collector is strengthened. Even under conditions of repeated charge and discharge causing material expansion and contraction, stable electrical contact can be maintained, effectively suppressing tab loosening or peeling, thereby improving the battery's cycle life and safety.

[0010] According to some embodiments of this application, the current collector includes a substrate layer and two conductive layers respectively disposed on both sides of the substrate layer. The tab is connected to one of the conductive layers. The first through hole penetrates at least the conductive layer connected to the tab and penetrates the substrate layer until it communicates with the other conductive layer, so that the conductive element electrically connects the tab and the two conductive layers.

[0011] According to some embodiments of this application, the conductive layer connected to the tab is designated as a first conductive layer, and the other conductive layer is designated as a second conductive layer, wherein the second conductive layer has a first surface connected to the substrate layer; The first through hole includes a first segment that penetrates the first conductive layer and a second segment that penetrates the substrate layer and connects to the first surface. One end of the conductive element passes through the first segment and the second segment and abuts against at least the hole wall of the first segment and the first surface.

[0012] According to some embodiments of this application, the conductive layer connected to the electrode tab is designated as a first conductive layer, and the other conductive layer is designated as a second conductive layer; The first through hole includes a first segment penetrating the first conductive layer, a second segment penetrating the substrate layer, and a third segment penetrating the second conductive layer. One end of the conductive element passes through the first segment, the second segment, and the third segment, and is connected to at least the hole wall of the first segment and the hole wall of the third segment.

[0013] According to some embodiments of this application, the current collector is made of metal foil, the depth of the first through hole is less than the thickness of the current collector, and / or the depth of the second through hole is less than the thickness of the tab.

[0014] An electrochemical device according to a second aspect of this application includes the electrode mentioned in any of the foregoing embodiments.

[0015] The electrode manufacturing method according to a third aspect embodiment of this application includes the following steps: Fix the electrode tab to the current collector; A second through hole is formed on the electrode tab and extends through to the current collector to form a first through hole; Conductive elements are provided in the first and second through holes so that the conductive elements are electrically connected to the electrode and the current collector, respectively.

[0016] According to some embodiments of this application, when the current collector includes a substrate layer and two conductive layers, in the step of processing the first through hole and the second through hole, the first through hole penetrates the conductive layer connected to the tab and penetrates the substrate layer until it communicates with the other conductive layer.

[0017] According to some embodiments of this application, the step of providing conductive elements in the first and second through holes is implemented in one of the following two ways: Prepare an independent conductive component, and pass the conductive component through the first through hole and the second through hole, and connect the conductive component to the electrode tab and the current collector; Alternatively, conductive material can be filled into the first and second through holes and cured to form the conductive element.

[0018] The electrode manufacturing method according to the fourth aspect of this application includes the following steps: Fix the electrode tab to the current collector; Prepare an independent conductive element and pass the conductive element through the electrode tab and the current collector.

[0019] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0020] The present application will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of the electrode structure according to an embodiment of this application; Figure 2 for Figure 1 Schematic diagram of the structure in the AA section; Figure 3 for Figure 2 Enlarged view of region B in the middle; Figure 4 for Figure 2 Enlarged schematic diagram of region B in the middle (an embodiment of a composite current collector). Figure 5 for Figure 2Enlarged schematic diagram of region B (another implementation of a composite current collector). Figure label: Active material layer 100; Current collector 200; substrate layer 201; first conductive layer 202; second conductive layer 203; first surface 204; empty foil area 205; first through hole 210; first segment 211; second segment 212; third segment 213; Electrode 300; Second through hole 310; Conductive component 400. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. The embodiments of this application may omit unnecessary detailed descriptions. For example, detailed descriptions of well-known matters and repeated descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art.

[0022] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0023] As used herein, the terms “approximately,” “generally,” “substantially,” and “about” are used to describe and indicate small variations. When used in conjunction with an event or situation, the terms may refer to examples in which the event or situation occurred precisely and examples in which the event or situation occurred very approximately. For example, when used in conjunction with numerical values, the terms may refer to a range of variation less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, if the difference between two numerical values ​​is less than or equal to ±10% of the average of the values ​​(e.g., less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%), then the two numerical values ​​can be considered “generally” the same.

[0024] Furthermore, for ease of description, "first," "second," "third," etc., can be used in this article to distinguish different components of a figure or a series of figures. "First," "second," "third," etc., are not intended to describe the corresponding components.

[0025] Additionally, quantities, ratios, and other numerical values ​​are sometimes presented in range format in this document. It should be understood that such range format is for convenience and brevity and should be interpreted flexibly to include not only the numerical values ​​explicitly specified as range limits, but also all individual numerical values ​​or subranges covered within the range, as if each numerical value and subrange were explicitly specified.

[0026] In the detailed description and claims, a list of items connected by the terms "one of," "among," "a kind of," or other similar terms may mean any of the listed items. For example, if items A and B are listed, then the phrase "one of A and B" means only A or only B. In another example, if items A, B, and C are listed, then the phrase "one of A, B, and C" means only A; only B; or only C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0027] In the detailed description and claims, the list of items connected by the term "at least one of" can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C.

[0028] In the following description, all figures disclosed in this application are approximate values, regardless of whether the terms "about" or "approximately" are used in conjunction. They may vary by 1%, 2%, 5%, or sometimes 10% to 20%. Whenever a range of values ​​with a lower limit (RL) and an upper limit (RU) is disclosed, any values ​​falling within that range are specifically disclosed. Specifically, the following values ​​within this range are specifically disclosed: R = RL + k * (RU - RL), where k is a variable with a 1% increment from 1% to 100%, i.e., k is 1%, 2%, 3%, 4%, 5%, ..., 50%, 51%, 52%, ..., 95%, 96%, 97%, 98%, 99%, or 100%. Furthermore, any range of values ​​defined by the two R values ​​as defined above are also specifically disclosed.

[0029] Throughout this specification, references to “implementation,” “partial implementation,” “one implementation,” “another approach,” “specific approach,” or “partial approach” mean that at least one implementation or embodiment in this application includes the specific features, structures, materials, or characteristics described in that implementation or embodiment.

[0030] In this application, numerical ranges are involved. Unless otherwise specified, the numerical ranges mentioned above are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Any lower limit can be combined with any upper limit to form a range not explicitly stated; and any lower limit can be combined with other lower limits to form a range not explicitly stated, just as any upper limit can be combined with any other upper limit to form a range not explicitly stated. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form a range not explicitly stated.

[0031] In the manufacturing of electrochemical energy storage devices such as lithium-ion batteries, the battery cell, as the core unit for energy storage and release, has its structural design and manufacturing process directly determining the battery's energy density, cycle life, safety, and production efficiency. A battery cell is made by stacking or winding electrode sheets, which include a current collector, an active material layer, and tabs connected to the empty foil area of ​​the current collector.

[0032] In traditional technology, the tab and the current collector are fixed by welding. However, welding is prone to problems such as incomplete welding or weak welds, resulting in a large internal resistance between the tab and the current collector.

[0033] To address the aforementioned problems, this application proposes an electrode, such as... Figures 1 to 3 As shown, the electrode includes a current collector 200, an active material layer 100, and tabs 300. The current collector 200 can be made of metal foil, such as copper foil or aluminum foil, or it can be composed of composite metal materials or surface-treated metal foil. The active material layer 100 is coated on the surface of the current collector 200, and can be coated on one or both sides of the current collector 200, partially or completely covering the surface area of ​​the current collector 200. The electrode also has an empty foil area 205, which is the area of ​​the current collector 200 that is not coated with active material. It should be explained that the empty foil area 205 can be an uncoated area reserved during the initial coating process, or it can be formed by subsequently scraping off the active material layer 100.

[0034] The tab 300, serving as a channel for current conduction and introduction, needs to be fixed in the empty foil area 205 and electrically connected to the current collector 200. Electrical connection methods include, but are not limited to, welding and bonding. It should be understood that if the tab 300 and current collector 200 are welded, problems such as incomplete soldering or over-soldering may occur, leading to increased contact resistance between the tab 300 and current collector 200. This affects the overall conductivity of the battery and can cause localized overheating during charging and discharging, reducing battery safety and cycle stability.

[0035] To reduce the contact resistance between the tab 300 and the current collector 200 and improve the conductivity between them, this application provides a first through-hole 210 in the empty foil area 205 of the current collector 200 and a second through-hole 310 on the tab 300, with the first through-hole 210 and the second through-hole 310 communicating with each other. It should be noted that the first through-hole 210 and the second through-hole 310 can be formed separately in the manufacturing processes of the current collector 200 and the tab 300. For example, the first through-hole 210 can be formed by stamping or laser processing during the manufacturing process of the current collector 200, and the second through-hole 310 can be processed during the forming process of the tab 300, thereby achieving communication between the first through-hole 210 and the second through-hole 310 during the assembly process of the tab 300 and the current collector 200. Alternatively, the first through hole 210 and the second through hole 310 can also be formed sequentially by stamping or laser processing after the tab 300 and the current collector 200 are assembled, to ensure precise alignment and connection between the two.

[0036] The electrode also includes a conductive element 400, part of which is disposed in the first through-hole 210 and the remaining part in the second through-hole 310. The conductive element 400 is made of a conductive material, such as titanium, nickel, tin, or their alloys. It should be noted that the conductive element 400 can be a structure in which conductive adhesive is filled into the first through-hole 210 and the second through-hole 310 and cured, or it can be a structure in which metal wires or conductive posts are inserted into the connected first through-hole 210 and the second through-hole 310 and pressed and fixed. The function of the conductive element 400 is to form a conductive path in the first through-hole 210 and the second through-hole 310, thereby effectively dispersing current, reducing local resistance, and preventing heat concentration.

[0037] Based on the above, by providing a first through-hole 210 and a second through-hole 310 connecting the current collector 200 and the tab 300, and embedding a conductive element 400 therein, current can be transmitted through multiple dispersed conductive paths, reducing the contact resistance between the tab 300 and the current collector 200. This avoids poor conductivity caused by incomplete soldering and over-soldering, and improves the stability of the battery under high-rate charge and discharge. In addition, since the two ends of the conductive element 400 are respectively embedded in the through-holes of the current collector 200 and the tab 300, the structural connection strength between the tab 300 and the current collector 200 is strengthened. Even under the condition of repeated charge and discharge of the battery causing material expansion and contraction, stable electrical contact can be maintained, effectively suppressing the loosening or peeling of the tab 300, thereby improving the cycle life and safety of the battery.

[0038] It is understood that the first through hole 210 and the second through hole 310 can be any shape, such as circular, elliptical, or polygonal. There can be multiple first through holes 210 and second through holes 310. The cross-sectional area of ​​a single through hole is in the range of 0.01 to 0.04 square millimeters to ensure uniform current density distribution and avoid stress concentration.

[0039] It should be noted that with the continuous advancement of battery cell technology, the electrode current collector 200 material has gradually evolved from traditional pure metal foil to composite current collector 200. Composite current collector 200 typically consists of a polymer layer in the middle and conductive metal layers on both sides. During welding, the conductive metal layers on both sides need to be welded through to achieve electrical conductivity. However, due to the thermal sensitivity of the polymer substrate, traditional welding methods easily cause the polymer layer to melt, shrink, or carbonize, resulting in a low yield rate for the battery cell.

[0040] Therefore, when this design is applied to an electrode with a composite current collector 200, it can avoid problems such as hot melting of the substrate layer 201 and damage to the electrode structure that are easy to occur when welding the tab 300 to the composite current collector 200, and effectively improve the welding yield and structural reliability of the composite current collector 200.

[0041] It should be noted that, as Figure 4 and Figure 5 As shown, the composite current collector 200 includes a substrate layer 201 and two conductive layers respectively disposed on both sides of the substrate layer 201. The substrate layer 201 is generally made of polymer material, which has the characteristics of being lightweight, flexible, and heat-resistant, and can improve the toughness of the electrode and reduce the overall weight. The conductive layers are usually made of metal materials, such as aluminum or copper, and are used to achieve efficient current transmission. In the prior art, when the tab 300 is connected to the conductive layer of the composite current collector 200 by welding, the current collector 200 needs to be welded through to achieve electrical conduction between the conductive layers on both sides and the tab 300. This process can easily cause the substrate layer 201 to melt at high temperatures, resulting in structural damage.

[0042] Therefore, in this embodiment, after the tab 300 is connected to one of the conductive layers, it achieves electrical connection with the other conductive layer through the communication structure of the first through-hole 210 and the second through-hole 310 and the conductive element 400 embedded therein, without needing to solder through the composite current collector 200. Specifically, for ease of description and understanding, the conductive layer connected to the tab 300 is named the first conductive layer 202, and the other conductive layer is named the second conductive layer 203. The first through-hole 210 at least penetrates the first conductive layer 202 and penetrates the substrate layer 201 until it communicates with the second conductive layer 203. It should be noted that the first through-hole 210 can extend into the second conductive layer 203, or even penetrate through the second conductive layer 203 (e.g., Figure 5 (As shown), or, the first via 210 may only penetrate the substrate layer 201 and communicate with the surface of the second conductive layer 203 (as shown). Figure 4 As shown in the figure, as long as effective contact between the conductive component 400 and the second conductive layer 203 can be achieved, it is acceptable.

[0043] To achieve the above structure, for example, the tab 300 can be pre-fixed by welding it to the first conductive layer 202. This welding only needs to establish an electrical connection between the tab 300 and the first conductive layer 202, without penetrating the substrate layer 201, thereby avoiding structural damage to the substrate layer 201 caused by high-temperature melting. Subsequently, a second through hole 310 is processed on the tab 300 and extends to the corresponding positions of the first conductive layer 202 and the substrate layer 201 to form a first through hole 210 that communicates with the second through hole 310. Finally, the conductive element 400 is embedded in the communication structure between the first through hole 210 and the second through hole 310 to electrically connect the tab 300 and the two conductive layers through the conductive element 400.

[0044] Based on the above, for the electrode structure containing the composite current collector 200, the reliable connection between the tab 300 and the double-sided conductive layer is achieved through the local conductive design, thereby reducing the welding requirements of the tab 300 and the conductive layer, effectively avoiding thermal damage to the substrate layer 201 caused by high-temperature welding, and improving the integrity and connection reliability of the composite current collector 200 structure.

[0045] Furthermore, the second conductive layer 203 is configured to have a first surface 204 that is connected to the substrate layer 201, such as... Figure 4 As shown, the first through hole 210 includes a first segment 211 that penetrates the first conductive layer 202 and a second segment 212 that penetrates the substrate layer 201 and connects to the first surface 204. One end of the conductive element 400 passes through the first segment 211 and the second segment 212 and abuts against the hole wall of the first segment 211 to realize the electrical connection between the conductive element 400 and the first conductive layer 202. The conductive element 400 also abuts against the first surface 204 to realize the electrical connection between the conductive element 400 and the second conductive layer 203.

[0046] Or, as Figure 5 As shown, the first through hole 210 includes a first segment 211 penetrating the first conductive layer 202 and a second segment 212 penetrating the substrate layer 201, as well as a third segment 213 penetrating the second conductive layer 203. One end of the conductive element 400 passes through the first segment 211, the second segment 212 and the third segment 213, and is connected to at least the hole wall of the first segment 211 and the hole wall of the third segment 213.

[0047] In some embodiments, the current collector 200 is made of metal foil, the depth of the first through-hole 210 is less than the thickness of the current collector 200, and / or, the depth of the second through-hole 310 is less than the thickness of the tab 300. Thus, various embodiments are possible. For example, if the depth of the first through-hole 210 is less than the thickness of the current collector 200, and the depth of the second through-hole 310 is equal to the thickness of the tab 300, this structure can be achieved by machining a through-hole 310 in the tab 300 and a non-through-hole 210 in the corresponding position in the current collector 200. For example, if the depth of the first through-hole 210 is equal to the thickness of the current collector 200, and the depth of the second through-hole 310 is less than the thickness of the tab 300, then a through-hole 210 can be machined in the current collector 200, and a blind-hole 310 can be formed in the tab 300.

[0048] Alternatively, the depth of the first through hole 210 can be less than the thickness of the current collector 200, and the depth of the second through hole 310 can be less than the thickness of the tab 300. In this case, both the first through hole 210 and the second through hole 310 are blind hole structures, which can be achieved by machining blind holes on the current collector 200 and the tab 300 respectively.

[0049] A second aspect of this application provides an electrochemical device comprising the electrodes mentioned in the above embodiments. The electrochemical device can be any device that undergoes an electrochemical reaction to convert chemical energy into electrical energy, and specific, non-limiting examples include all types of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. In particular, the electrochemical device is a lithium secondary battery, including lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, or lithium-ion polymer secondary batteries.

[0050] A third aspect of this application also provides a method for manufacturing an electrode sheet, used to manufacture the electrode sheet structure described in the above embodiments. The electrode sheet manufacturing method includes the following steps: S100, Fix the tab 300 onto the current collector 200; In this step, the tab 300 can be fixed to the current collector 200 by means of gluing, welding or other methods.

[0051] S200, A second through hole 310 is formed on the tab 300 and extends through to the current collector 200 to form a first through hole 210; In this step, the first through hole 210 and the second through hole 310 can be formed by means of stamping, machining, laser drilling, etc.

[0052] S300, a conductive element 400 is provided in the first through hole 210 and the second through hole 310 so that the conductive element 400 is electrically connected to the tab 300 and the current collector 200 respectively.

[0053] In this step, the conductive element 400 can be disposed in the first through hole 210 and the second through hole 310 in one of the following two ways: First, the first through hole 210 and the second through hole 310 are filled with conductive material and then cured to form the conductive element 400. At this time, the conductive material can be conductive adhesive, low melting point metal or its alloy, and is cured at room temperature, melted and then cooled to form the conductive element 400 that is tightly bonded to the hole wall; Second, an independent conductive element 400 is prepared. It should be noted that the independent conductive element 400 refers to a solid structure made of conductive material in advance, such as a conductive post or conductive rivet, which is pressed into or inserted into the first through hole 210 and the second through hole 310 to achieve physical contact and electrical connection with the tab 300 and the current collector 200.

[0054] The fourth aspect of this application proposes another method for manufacturing electrode sheets. This method does not require pre-forming through holes on the electrode tab 300 and the current collector 200. Instead, it simultaneously forms the first through hole 210 and the second through hole 310 through the piercing process of the conductive element 400. Specifically, it includes the following steps: S100, Fix the tab 300 onto the current collector 200; S200. Prepare an independent conductive component 400 and pass the conductive component 400 through the tab 300 and the current collector 200.

[0055] In this step, pressure is applied to the piercing end of the conductive component 400, causing it to penetrate the tab 300 and the current collector 200. During the penetration process, a first through-hole 210 and a second through-hole 310 are simultaneously formed, achieving mechanical anchoring and electrical connection between the conductive component 400, the tab 300, and the current collector 200. This piercing process can be performed at room temperature without additional heating or subsequent curing steps, which improves production efficiency and reduces process complexity. The piercing end of the conductive component 400 should have sufficient hardness to penetrate the metal layer, while the overall structure must ensure that it does not yield or deform after penetration. The conductive component 400 can be a metal rivet or conductive post with a sharp tip, and its material can be copper, aluminum, nickel, or their alloys to ensure good conductivity and mechanical strength. After piercing, the sidewall of the conductive component 400 fits tightly against the hole wall, forming a stable electrical connection, while simultaneously establishing a low-resistance path between the current collector 200 and the tab 300. This structure is suitable for high-rate charge / discharge scenarios, improving battery cycle life and safety performance.

[0056] In some embodiments, the process further includes step S300: flattening the exposed portion of the conductive element 400 to reduce the risk of short circuits during assembly. This can be achieved by rolling, stamping, or grinding to ensure that the surface flatness of the electrode meets the requirements of subsequent winding or stacking processes.

[0057] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limiting the present application, and that changes, substitutions and modifications can be made to the embodiments without departing from the spirit, principles and scope of the present application.

Claims

1. An electrode, characterized in that, include: Active material layer; A current collector, wherein at least one side of the current collector is coated with the active material layer, and the current collector is further provided with an empty foil area, wherein the current collector in the empty foil area is not coated with the active material layer, and the current collector has a first through hole in the empty foil area; The electrode tab is fixed to the empty foil area and connected to the current collector. The electrode tab has a second through hole, which communicates with the first through hole. The electrode further includes a conductive element, part of which is disposed in the first through hole and the remaining part is disposed in the second through hole, so that the electrode tab and the current collector are electrically connected.

2. The electrode sheet according to claim 1, characterized in that, The current collector includes a substrate layer and two conductive layers respectively disposed on both sides of the substrate layer. The electrode is connected to one of the conductive layers. The first through hole penetrates at least the conductive layer connected to the electrode and penetrates the substrate layer until it communicates with the other conductive layer, so that the conductive element electrically connects the electrode and the two conductive layers.

3. The electrode sheet according to claim 2, characterized in that, The conductive layer connected to the electrode tab is designated as a first conductive layer, and the other conductive layer is designated as a second conductive layer. The second conductive layer has a first surface that is connected to the substrate layer. The first through hole includes a first segment that penetrates the first conductive layer and a second segment that penetrates the substrate layer and connects to the first surface. One end of the conductive element passes through the first segment and the second segment and abuts against at least the hole wall of the first segment and the first surface.

4. The electrode sheet according to claim 2, characterized in that, The conductive layer connected to the electrode tab is designated as the first conductive layer, and the other conductive layer is designated as the second conductive layer; The first through hole includes a first segment penetrating the first conductive layer, a second segment penetrating the substrate layer, and a third segment penetrating the second conductive layer. One end of the conductive element passes through the first segment, the second segment, and the third segment, and is connected to at least the hole wall of the first segment and the hole wall of the third segment.

5. The electrode sheet according to claim 1, characterized in that, The current collector is made of metal foil, the depth of the first through hole is less than the thickness of the current collector, and / or the depth of the second through hole is less than the thickness of the tab.

6. An electrochemical device, characterized in that, The electrochemical device includes the electrode as described in any one of claims 1 to 5.

7. A method for manufacturing an electrode sheet, characterized in that, Includes the following steps: Fix the electrode tab to the current collector; A second through hole is formed on the electrode tab and extends through to the current collector to form a first through hole; Conductive elements are provided in the first and second through holes so that the conductive elements are electrically connected to the electrode and the current collector, respectively.

8. The electrode manufacturing method according to claim 7, characterized in that, When the current collector includes a substrate layer and two conductive layers, in the step of processing the first through hole and the second through hole, the first through hole penetrates the conductive layer connected to the tab and penetrates the substrate layer until it communicates with the other conductive layer.

9. The electrode manufacturing method according to claim 7, characterized in that, The step of setting conductive elements in the first and second through holes is implemented using one of the following two methods: Prepare an independent conductive component, and pass the conductive component through the first through hole and the second through hole, and connect the conductive component to the electrode tab and the current collector respectively; Alternatively, conductive material can be filled into the first and second through holes and cured to form the conductive element.

10. A method for manufacturing an electrode sheet, characterized in that, Includes the following steps: Fix the electrode tab to the current collector; Prepare an independent conductive element and pass the conductive element through the electrode tab and the current collector.

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