Pole piece assembly, electrochemical device, and electronic device

Abstract

The utility model relates to electrochemical energy storage technical field discloses a kind of pole piece assembly, electrochemical device and electronic equipment, pole piece assembly includes pole piece and tab, pole piece includes current collector, the side of current collector along thickness direction has first surface, and first surface includes at least two first blank area arranged at intervals;Tab includes conducting part and at least two first legs, each first leg is connected to conducting part;Each first leg is stacked and connected to a first blank area, and conducting part is located on the outside of the edge of current collector, so as to improve the charge rate of electrochemical device.

Description

Technical Field

[0001] This utility model relates to the field of electrochemical energy storage technology, and in particular to electrode components, electrochemical devices, and electronic equipment. Background Technology

[0002] With the rapid development of new energy vehicles and fast-charging mobile devices, the market has placed higher demands on battery charging rates.

[0003] In existing technologies, most batteries adopt a single tab structure, that is, a single tab is welded to the current collector by a welding process. There is only a single conductive channel for current to pass through between the tab and the current collector. For areas on the current collector that are far from the tab, the current flow path is long and the resistance is high, which makes it difficult for the current to quickly and evenly fill the entire current collector. The efficiency of current filling the current collector will directly affect the charging rate of the battery, resulting in a lower charging rate of the battery. Utility Model Content

[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 assembly capable of improving the charging rate of an electrochemical device.

[0005] This application also proposes an electrochemical device having the above-mentioned electrode assembly, and an electronic device having the electrochemical device.

[0006] An electrode assembly according to a first aspect of this application includes an electrode and a tab. The electrode includes a current collector, and one side of the current collector along the thickness direction has a first surface, the first surface including at least two spaced first blank areas. The tab includes a conductive portion and at least two first legs, each first leg being connected to the conductive portion. Each first leg is stacked and connected to a first blank area, and the conductive portion is located outside the edge of the current collector.

[0007] The electrode assembly according to the embodiments of this application has at least the following beneficial effects: by setting the electrode tab to include a conductive part and at least two first legs, each first leg being connected to the conductive part, and setting at least two first blank areas on the first surface of the current collector along the thickness direction, with each first leg stacked and connected to a first blank area, there can be multiple conductive channels between the electrode tab and the current collector, and the current can enter the current collector from multiple conductive channels, shortening the path of the current flowing to the area on the current collector that is far away from the electrode tab, reducing impedance and temperature rise, and the current can more quickly fill all areas of the current collector, thereby improving the charging rate of the electrochemical device.

[0008] In some embodiments, the current collector includes a plurality of straight sections and a plurality of bent sections, the straight sections and bent sections being alternately connected along the winding direction of the electrode sheet; each first blank area is distributed in a different straight section.

[0009] In some embodiments, each first leg and conductive part are integrally formed.

[0010] In some embodiments, the electrode assembly further includes a first conductive adhesive layer, through which each first leg and the first blank area are bonded.

[0011] In some embodiments, the electrode further includes a first active layer and a second active layer, the first surface is coated with the first active layer, and the current collector has a second surface that is spaced apart from the first surface along the thickness direction, the second surface being coated with the second active layer; wherein, the first active layer is provided with a plurality of first grooves, and each first blank area is exposed through a first groove.

[0012] In some embodiments, the first groove has a first opening located at the edge of the first active layer, and the first leg passes through the first opening.

[0013] In some embodiments, the electrode further includes a first active layer and a second active layer, and the current collector has a second surface on the other side along the thickness direction. The first surface is coated with the first active layer, and the second surface is coated with the second active layer. The first active layer is provided with at least one first groove. At least one first blank area is located at one end of the current collector along the winding direction, and the remaining first blank areas are exposed through a first groove.

[0014] In some embodiments, the current collector includes a first conductive layer, an insulating layer, and a second conductive layer connected in sequence. The first conductive layer has a first surface on the side facing away from the insulating layer, and the second conductive layer has a second surface on the side facing away from the insulating layer. The tab also includes at least two second legs, each of which is connected to a conductive portion. The second surface includes a plurality of second blank areas, and each second leg is stacked and connected to a second blank area. The second active layer is provided with a plurality of second grooves, and each second blank area is exposed through a second groove. Alternatively, the second active layer is provided with at least one second groove, at least one second blank area is located at one end of the current collector along the winding direction, and the remaining second blank areas are exposed through a second groove.

[0015] In some embodiments, the electrode assembly further includes a first adhesive tape, with each first leg corresponding to one first adhesive tape; the first adhesive tape is bonded to the first active layer and / or current collector and covers the first leg.

[0016] An electrochemical device according to a second aspect of this application includes the electrode assembly from any of the above embodiments.

[0017] An electronic device according to a third aspect of this application is characterized in that it includes the electrochemical device described in the above embodiments.

[0018] 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

[0019] The embodiments described in this application are not limited to the accompanying drawings, which are only some of the embodiments described herein. Those skilled in the art can obtain drawings of other embodiments based on the content of this application.

[0020] Figure 1 A partial cross-sectional view of the wound battery cell provided in an embodiment of this application is shown. Figure 2 A schematic diagram of the electrode sheet provided in the embodiment of this application in its unfolded state is shown; Figure 3 A cross-sectional view of the electrode assembly provided in the embodiment of this application in its unfolded state is shown. Figure 4 This illustration shows a cross-sectional view of an electrode assembly in its unfolded state, according to another embodiment of this application. Figure 5 A schematic diagram of a partially cut-out structure of a wound battery cell provided in another embodiment of this application is shown.

[0021] Figure label: Electrode assembly 100; Electrode 110; Current collector 111; First blank area 1111; Straight section 1115; Bending section 1117; First conductive layer 1119; Insulating layer 1121; Second conductive layer 1123; First active layer 113; First groove 1131; Second active layer 115; Tab 130; Conductive part 131; First support 133; Second support 135; First conductive adhesive layer 150; Second conductive adhesive layer 160; First adhesive tape 170; Separator 300; Winding direction X. Detailed Implementation

[0022] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0023] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0024] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0025] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0026] In the description of this utility model, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0027] This application provides an electronic device, which includes an electrochemical device. The electronic device in this application is not particularly limited and can be any electronic device known in the prior art.

[0028] The electronic devices described in this application are not particularly limited in their application and can be used with any electronic device known in the prior art. These electronic devices include, but are not limited to, mobile phones, smartphones, laptops, tablets, wearable devices, smartwatches, smart bracelets, smart glasses, power banks, televisions, game consoles, game controllers, digital cameras, smart speakers, headphones, keyboards, mice, monitors, drones, audio equipment, home appliances, toys, power tools, automobiles, motorcycles, electric bicycles, bicycles, robots, robotic dogs, industrial robots, and android robots.

[0029] In some embodiments, the electrochemical device includes any device in which an electrochemical reaction occurs to interconvert chemical energy and 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.

[0030] Please see Figure 1 In some embodiments, the electrochemical device includes a housing and a battery cell located within the housing. The battery cell includes a separator 300 and two electrode assemblies 100 with opposite polarities. The separator 300 is located between the two electrode assemblies 100 to isolate them. One of the two electrode assemblies 100 is a positive electrode assembly, and the other is a negative electrode assembly.

[0031] The battery cell can be a wound battery cell (such as...) Figure 1 (As shown) or laminated cells, the specific structure can be referred to in existing technology, and will not be repeated here. For ease of description, the following explanation will take wound cells as an example.

[0032] Please see Figures 1 to 3 In some embodiments, the electrode assembly 100 includes an electrode 110 and a tab 130. The electrode 110 includes a current collector 111, and the tab 130 includes a conductive portion 131 and at least two first legs 133.

[0033] Among them, electrode 110 can be either a positive electrode or a negative electrode, and current collector 111 can be a single-layer metal foil (such as...). Figure 1 (As shown).

[0034] The conductive part 131 is located on the outer side of the edge of the current collector 111, so as to be directly or indirectly connected to the external circuit through the conductive structure.

[0035] The current collector 111 has a first surface on one side along the thickness direction. The first surface includes at least two first blank areas 1111. Each first leg 133 is connected to the conductive part 131. Each first leg 133 is stacked and connected to a first blank area 1111, so that there can be multiple conductive channels between the tab 130 and the current collector 111. Current can enter the current collector 111 from multiple conductive channels, shortening the path of current flow to areas on the current collector 111 that are far away from the tab 130, reducing impedance and temperature rise. Current can be distributed to various areas of the current collector 111 more quickly, improving the charging rate of the electrochemical device.

[0036] Each first blank area 1111 is spaced apart, so the conduction channels between each first support 133 and current collector 111 are more dispersed, which helps to further improve the charging rate of the electrochemical device.

[0037] The number of the first leg 133 can be two or three (e.g., ...). Figure 1 (As shown), four, five or other quantities, the number of first blank areas 1111 can be equal to the number of first feet 133, and each first foot corresponds to one first blank area 1111.

[0038] The extension length of each first leg 133 along the current collector 111 toward the tab 130 can be equal or unequal, and can be flexibly set according to the requirements.

[0039] Electrical connection between the first foot 133 and the first blank area 1111 can be achieved by welding, bonding or other methods.

[0040] In some embodiments, the current collector 111 may include a plurality of straight sections 1115 and a plurality of bent sections 1117 (e.g., ...). Figure 2 (As shown).

[0041] Among them, the straight section 1115 and the bent section 1117 can be alternately connected along the winding direction of the electrode 110.

[0042] As an example, the battery cell can be a wound battery cell, which can include a straight section and two corner sections, with the straight section connected between the two corner sections. After the electrode 110 is wound, each straight section 1115 can be located in the straight section, and each bent section 1117 can be distributed in the two corner sections. The specific structure can be referred to the prior art, and will not be described in detail here. Figure 1 This is a schematic diagram of a partially cut-out structure of a wound battery cell with a current collector made of commonly used single-layer metal foil in the flat region.

[0043] Each first blank area 1111 is distributed in a different straight section 1115, so each first foot 133 can be connected to a different straight section 1115 respectively, which helps the current to flow to each area of ​​the current collector 111 more quickly, improves the charging rate of the electrochemical device, and the current distribution is also more uniform.

[0044] When the electrode 110 is wound into a cell, each first leg 133 can be arranged relative to the other along the thickness direction of the first leg 133. Specifically, the projections of each first leg 133 on a plane perpendicular to the thickness direction of the first leg 133 overlap, which helps to avoid the situation where the first leg 133 is tilted and the first blank area 1111 needs to be increased to place the first leg 133.

[0045] In some embodiments, each first leg 133 and conductive part 131 are integrally formed, thereby avoiding solder joints on the tab 130, reducing contact resistance, improving the reliability of conductivity, simplifying the manufacturing process of the tab 130, and improving the production efficiency of the tab 130.

[0046] As an example, the tab 130 can be formed by rolling multiple metal sheets into a single structure, and the number of metal sheets can be equal to the number of first legs 133. The metal sheets can be stacked sequentially, and one end of each metal sheet can be rolled into a single piece to form a conductive part 131. The other end of each metal sheet can serve as a first leg 133.

[0047] In some embodiments, the sum of the thicknesses of each first leg 133 is less than or equal to the thickness of the conductive portion 131, which helps the conductive portion 131 to have a greater thickness to improve current carrying capacity, and the overall structure of the tab 130 is more balanced.

[0048] In some embodiments, the electrode assembly 100 may further include a first conductive adhesive layer 150.

[0049] Each first pin 133 and the first blank area 1111 are bonded together by a first conductive adhesive layer 150. That is, the first conductive adhesive layer 150 is bonded between the first pin 133 and the first blank area 1111, so that the first pin 133 and the current collector 111 can be electrically connected through the first conductive adhesive layer 150 to realize the electrical connection between the tab 130 and the electrode 110. Compared with the prior art of welding the tab 130 to the electrode 110, in this embodiment, the thickness of the first conductive adhesive layer 150 is smaller than the thickness of the solder, which helps to reduce the thickness of the stacked connection between the tab 130 and the electrode 110. When the electrode assembly 100 is applied to the battery cell, it can reduce the size of the battery cell, increase the energy density of the battery cell, and avoid the situation where the burrs of the solder puncture the separator 300, thus improving the safety performance of the battery cell.

[0050] In some embodiments, the first conductive adhesive layer 150 can be a room-temperature solid conductive adhesive that can be cured at room temperature, eliminating the need for high-temperature curing and simplifying the process.

[0051] As an example, the room temperature solid conductive adhesive includes components such as an adhesive, metal powder, diluent, curing agent, accelerator, and coupling agent. The adhesive accounts for ≥5% and ≤50% of the room temperature solid conductive adhesive to ensure its adhesive performance. The adhesive can be one or more of epoxy resin, silicone resin, or polyimide resin matrix, or other types of adhesives. The metal powder is micron-sized and / or nano-sized powder particles. The adhesive includes a single component or a mixture of metal components. The metal powder can be powder of at least one metal selected from gold, silver, copper, aluminum, zinc, iron, and nickel. The first conductive adhesive layer 150 may also include graphite or other conductive compounds. The metal powder accounts for ≥20% and ≤90% of the room temperature solid conductive adhesive to ensure its conductivity. After application, as the solvent evaporates, the adhesive cures and shrinks, and the metal powder particles begin to aggregate. Upon complete curing, a solid adhesive layer is formed, in which the metal particles are tightly connected, forming a stable and continuous conductive path.

[0052] Understandably, the first conductive adhesive layer 150 can also be made of other conductive adhesives besides room temperature solid conductive adhesives, and the specific choice can be made flexibly according to the requirements.

[0053] In some embodiments, the electrode 110 may further include a first active layer 113 and a second active layer 115.

[0054] The first surface is coated with a first active layer 113, and the current collector 111 also has a second surface that is spaced apart from the first surface along the thickness direction, and the second surface is coated with a second active layer 115.

[0055] When the electrode 110 is a positive electrode, both the first active layer 113 and the second active layer 115 can be positive active material layers; when the electrode 110 is a negative electrode, both the first active layer 113 and the second active layer 115 can be negative active material layers.

[0056] The first active layer 113 may have multiple first grooves 1131, and each first blank area 1111 can be exposed through a first groove 1131, thereby allowing the first blank area 1111 to be positioned between the two ends of the current collector 111. The electrode assembly 100 adopts a centrally located tab 130 structure (e.g., Figure 3 As shown in the figure, the current distribution is more uniform. In addition, this embodiment also provides multiple first pins 133, and there are multiple conductive paths between the tab 130 and the current collector 111, which further shortens the current transmission path and makes the current distribution more uniform.

[0057] The electrode assembly 100 can also adopt other structures besides the centrally located electrode tab 130. Specifically, in some embodiments, the first active layer 113 can be provided with at least one first groove 1131, and at least one first blank area 1111 is located at one end of the current collector 111 along the winding direction (e.g., Figure 4 As shown), each of the remaining first blank areas 1111 is exposed through a first groove 1131, thereby reducing the number of first grooves 1131, which helps to reduce damage to the first active layer 113 and improve the energy storage performance of the electrochemical device.

[0058] In some embodiments, the first groove 1131 may have a first opening, which may be located at the edge of the first active layer 113. The first support 133 may be inserted through the first opening, so that the first groove 1131 may be open towards the edge of the first active layer 113. This helps to avoid the first support 133 from being stacked on the first active layer 113 and affecting the thickness of the electrode 110, and can reduce the impact on the energy density of the electrochemical device.

[0059] As an example, the first groove 1131 can penetrate the first active layer 113 along the thickness direction of the electrode 110, so that a portion of the first surface is exposed through the first groove 1131, and the exposed portion of the first surface can be the first blank area 1111. The first groove 1131 may include a first groove wall, a second groove wall, and a third groove wall connected in sequence. The first groove opening and the second groove wall can be spaced apart and opposite each other along the width direction of the electrode 110. The second groove wall and the third groove wall can be spaced apart and opposite each other along the winding direction.

[0060] In some embodiments, the area of ​​the first blank area 1111 is greater than the coverage area of ​​the first conductive adhesive layer 150 in the first blank area 1111, which helps to reduce the situation where the conductive adhesive flows to the edge of the first groove 1131 and overflows, thus reducing the impact on the thickness of the electrode 110.

[0061] In some embodiments, the coverage area of ​​the first conductive adhesive layer 150 in the first blank area 1111 is greater than or equal to the projected area of ​​the first foot 133 in the first blank area 1111. This helps to increase the bonding area of ​​the first conductive adhesive layer 150 between the first foot 133 and the first blank area 1111, thereby improving the bonding strength between the first foot 133 and the first blank area 1111. Specifically, the projections of the first conductive foot in the first blank area 1111 and the projections of the first conductive adhesive layer 150 in the first blank area 1111 overlap, and the coverage area of ​​the first conductive adhesive layer 150 in the first blank area 1111 is greater than or equal to the projected area of ​​the first foot 133 in the first blank area 1111. Please refer to [link / reference]. Figure 1 , Figure 3 and Figure 4 In some embodiments, the electrode assembly 100 may also include a first adhesive tape 170.

[0062] Each first foot 133 corresponds to a first adhesive tape 170. The first adhesive tape 170 is bonded to the first active layer 113 and / or the current collector 111 and covers the first foot 133. This helps to prevent burrs on the first foot 133 from puncturing the diaphragm 300 and further improves the safety performance of the electrochemical device.

[0063] In addition, in this embodiment, the first leg 133 is bonded to a first blank area 1111 by the first conductive adhesive layer 150, which also helps to reduce the number of first adhesive tapes 170, thereby optimizing the size of the battery cell and improving the energy density of the battery cell.

[0064] Specifically, in the relevant existing technologies, the tabs and electrodes are usually fixed by welding processes such as ultrasonic welding and laser welding. After welding, there are weld marks on both sides of the electrode. Therefore, it is necessary to stick adhesive tape on both sides of the electrode to cover the weld marks on both sides of the electrode to avoid burrs piercing the diaphragm.

[0065] In this embodiment, since the first support 133 and the first blank area 1111 are bonded and fixed by the first conductive adhesive layer 150, there are no solder marks on either side of the electrode 110. Only the first adhesive tape 170 is needed to cover the first support 133. The electrode 110 is flat on the side opposite to the tab 130, so the first adhesive tape 170 is not required, thus reducing the number of first adhesive tapes 170. Understandably, when both the positive and negative electrode assemblies in the electrochemical device use the electrode assembly 100 of this embodiment, the number of first adhesive tapes 170 in both the positive and negative electrode assemblies is reduced accordingly, which helps to further optimize the size of the electrochemical device and improve its energy density.

[0066] Furthermore, in existing technologies, the negative electrode active material layer on the negative electrode sheet requires two additional adhesive tapes to cover part of the negative electrode active material layer. These two adhesive tapes must align one-to-one with the two first grooves on the adjacent inner and outer positive electrode sheets after the negative electrode sheet is wound into a battery cell, to prevent the negative electrode active material layer in the adhesive-covered area from participating in the reaction and causing lithium plating. Similarly, the positive electrode active material layer on the positive electrode sheet requires two additional adhesive tapes to cover part of the positive electrode active material layer. These two adhesive tapes must align one-to-one with the two first grooves on the adjacent inner and outer negative electrode sheets after the positive electrode sheet is wound into a battery cell, to prevent the positive electrode active material layer in the adhesive-covered area from participating in the reaction and causing lithium plating. Including the adhesive tape covering the first grooves, existing technologies require adhesive tape to be adhered to four locations on both the positive and negative electrode sheets, significantly impacting the battery cell size and reducing its energy density.

[0067] In this embodiment, when the electrode 110 is a negative electrode, the negative electrode only has a first groove 1131 on one side of the first active layer 113, and the second active layer 115 has a complete structure. Therefore, after the negative electrode is wound into a battery cell, the positive electrode of the adjacent layer only needs to be pasted with second adhesive tape at each location opposite to the first groove 1131 (the first groove 1131 on the negative electrode). Since the second active layer 115 of the negative electrode has a complete structure, there is no need to paste second adhesive tape on the side of the positive electrode opposite to the second active layer 115 of the negative electrode, which reduces the number of second adhesive tapes, optimizes the size of the electrochemical device, and improves the energy density of the electrochemical device.

[0068] Similarly, when the electrode 110 is a positive electrode, the positive electrode only has a first groove 1131 on one side of the first active layer 113, and the second active layer 115 has a complete structure. Therefore, after the positive electrode is wound into a cell, the negative electrode of the adjacent layer only needs to be pasted with third adhesive tape at each location opposite to the first groove 1131 (the first groove 1131 on the positive electrode). Since the second active layer 115 of the positive electrode has a complete structure, there is no need to paste third adhesive tape on the side of the negative electrode opposite to the second active layer 115 of the positive electrode, which reduces the number of third adhesive tapes, optimizes the size of the electrochemical device, and improves the energy density of the electrochemical device.

[0069] It should be noted that, in addition to using a single-layer metal foil, the current collector 111 can also use a composite current collector (such as...). Figure 5 (As shown), specifically, please refer to Figure 2 and Figure 5 In some embodiments, the current collector 111 may include a first conductive layer 1119, an insulating layer 1121, and a second conductive layer 1123 connected in sequence.

[0070] The first conductive layer 1119 may have a first surface on the side opposite to the insulating layer 1121, that is, each first leg 133 may be connected to each first blank area 1111 on the first surface.

[0071] The tab 130 also includes at least two second pins 135, each of which is connected to the conductive part 131, that is, each first pin 133 and each second pin 135 can converge at the conductive part 131.

[0072] The side of the second conductive layer 1123 opposite to the insulating layer 1121 may have a second surface, and the first surface and the second surface may be two opposite surfaces of the current collector 111 spaced apart along the thickness direction.

[0073] The second surface may include multiple second blank areas, and each second foot 135 is stacked and connected to a second blank area, thereby enabling the first conductive layer 1119 and the second conductive layer 1123 to conduct electricity, realizing the charging and discharging function of the electrochemical device. In addition, since there are multiple conductive paths between the tab 130 and the first conductive layer 1119 and the second conductive layer 1123 respectively, the charging rate of the electrochemical device can also be improved for the electrochemical device using a composite current collector.

[0074] As an example, along the thickness direction of the first foot 133, the first foot 133 and the second foot 135 can be alternately distributed, that is, one first foot 133 and one second foot 135 can be a set of conductive feet, and each set of conductive feet corresponds to a straight segment 1115. Specifically, along the thickness direction of the first foot 133, the projections of each first foot 133 and each second foot 135 on a plane perpendicular to the thickness direction of the first foot 133 overlap. This helps to avoid the situation where the first foot 133 is tilted, which would require increasing the first blank area 1111 to place the first foot 133, or helps to avoid the situation where the second foot 135 is tilted, which would require increasing the second blank area to place the second foot 135.

[0075] It should be noted that the number of the first leg 133 and the number of the second leg 135 can be equal or unequal.

[0076] In some embodiments, the electrode assembly 100 may further include a second conductive adhesive layer 160, and each second leg 135 is bonded to a second blank area by a second conductive adhesive layer 160.

[0077] The second conductive adhesive layer 160 can be made of the same material as the first conductive adhesive layer 150, which will not be described in detail here.

[0078] The area relationship and beneficial effects of the second conductive adhesive layer 160, the second blank area, and the second support 135 can be referred to the area relationship and beneficial effects of the first conductive adhesive layer 150, the first blank area 1111, and the first support 133 in the above embodiments, and will not be repeated here.

[0079] In some embodiments, the sum of the thicknesses of each first leg 133 and each second leg 135 is less than or equal to the thickness of the conductive portion 131, which helps the conductive portion 131 to have a greater thickness to improve current carrying capacity, and the overall structure of the tab 130 is more balanced.

[0080] In some embodiments, the second active layer 115 may be provided with a plurality of second grooves, each second blank area is exposed through a second groove, and each second foot 135 may be located in a second groove and connected to the second blank area. Thus, for the electrode assembly 100 using a composite current collector, the electrode assembly 100 may also adopt a centrally located tab 130 structure to shorten the current transmission path. The specific beneficial effects can be referred to the electrode assembly 100 with centrally located tab 130 using metal conductive foil in the above embodiments, and will not be repeated here.

[0081] The first groove 1131 and the second groove can be arranged opposite each other along the thickness direction of the electrode 110, or they can be staggered.

[0082] Understandably, for the electrode assembly 100 using a composite current collector, the electrode assembly 100 may also adopt other structures besides the centrally located tab 130. Specifically, in some embodiments, the second active layer 115 is provided with at least one second groove, and at least one second blank area is located at one end of the current collector 111 along the winding direction. The remaining second blank areas are exposed through a second groove, thereby reducing the number of the first groove 1131 and the second groove, which helps to reduce damage to the first active layer 113 and the second active layer 115 and improves the energy storage performance of the electrochemical device.

[0083] In some embodiments, the second groove may have a second opening, which may be located at the edge of the second active layer 115. The second support 135 may be inserted through the second opening, so that the second groove can be open towards the edge of the second active layer 115. This helps to avoid the second support 135 from being stacked on the second active layer 115 and affecting the thickness of the electrode 110, thereby reducing the impact on the energy density of the electrochemical device.

[0084] As an example, the second groove can penetrate the second active layer 115 along the thickness direction of the electrode 110, so that a portion of the second surface is exposed through the second groove, and the exposed portion of the second surface can be the second blank area. The second groove may include a fourth groove wall, a fifth groove wall, and a sixth groove wall connected in sequence, and the second groove opening and the fifth groove wall can be spaced apart and opposite each other along the width direction of the electrode 110. The fourth groove wall and the sixth groove wall can be spaced apart and opposite each other along the winding direction.

[0085] Understandably, the first slot and the second slot can be located on the same side of the electrode 110 along the width direction.

[0086] In some embodiments, the electrode assembly 100 may further include a second adhesive tape, with each second leg 135 corresponding to one second adhesive tape. The second adhesive tape is bonded to the second active layer 115 and / or the second conductive layer 1123 and covers the second leg 135, which helps to prevent burrs on the second leg 135 from puncturing the diaphragm 300 and further improves the safety performance of the electrochemical device.

[0087] In the electrode assembly 100, electrochemical device, and electronic device provided in this application embodiment, by configuring the tab 130 to include a conductive part 131 and at least two first legs 133, each first leg 133 being connected to the conductive part 131, and at least two first blank areas 1111 being provided on the first surface of the current collector 111 along the thickness direction, with each first leg 133 stacked and connected to a first blank area 1111, multiple conductive channels can be provided between the tab 130 and the current collector 111. Current can enter the current collector 111 from multiple conductive channels, shortening the path of current flow to areas on the current collector 111 that are far from the tab 130, reducing impedance and temperature rise, and allowing current to more quickly fill all areas of the current collector 111, thereby improving the charging rate of the electrochemical device.

[0088] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. An electrode assembly, characterized in that, include: An electrode includes a current collector, the current collector having a first surface on one side along the thickness direction, the first surface including at least two spaced first blank areas; The electrode includes a conductive portion and at least two first legs, each of which is connected to the conductive portion; each of the first legs is stacked and connected to a first blank area, and the conductive portion is located outside the edge of the current collector.

2. The electrode assembly according to claim 1, characterized in that, The current collector includes multiple straight sections and multiple bent sections, which are alternately connected along the winding direction of the electrode sheet; Each of the first blank areas is distributed in a different straight segment.

3. The electrode assembly according to claim 1, characterized in that, Each of the first legs and the conductive part are integrally formed.

4. The electrode assembly according to claim 1, characterized in that, The electrode assembly further includes a first conductive adhesive layer, through which each of the first legs and the first blank area are bonded.

5. The electrode assembly according to claim 4, characterized in that, The electrode further includes a first active layer and a second active layer. The first surface is coated with the first active layer, and the current collector also has a second surface that is spaced apart from the first surface along the thickness direction. The second surface is coated with the second active layer. The first active layer is provided with a plurality of first grooves, and each first blank area is exposed through one of the first grooves.

6. The electrode assembly according to claim 4, characterized in that, The electrode further includes a first active layer and a second active layer, and the current collector has a second surface on the other side along the thickness direction. The first surface is coated with the first active layer, and the second surface is coated with the second active layer. The first active layer is provided with at least one first groove; At least one of the first blank areas is located at one end of the current collector along the winding direction, and the remaining first blank areas are exposed through one of the first grooves.

7. The electrode assembly according to any one of claims 5 to 6, characterized in that, The first groove has a first opening, which is located at the edge of the first active layer, and the first support leg passes through the first opening.

8. The electrode assembly according to any one of claims 5 to 6, characterized in that, The current collector includes a first conductive layer, an insulating layer, and a second conductive layer connected in sequence. The first conductive layer has a first surface on the side opposite to the insulating layer, and the second conductive layer has a second surface on the side opposite to the insulating layer. The electrode tab further includes at least two second legs, each of which is connected to the conductive part; the second surface includes a plurality of second blank areas, each of which is stacked and connected to one second blank area; The second active layer is provided with a plurality of second grooves, and each second blank area is exposed through a second groove; or, the second active layer is provided with at least one second groove, at least one second blank area is located at one end of the current collector along the winding direction, and the remaining second blank areas are exposed through a second groove respectively.

9. The electrode assembly according to any one of claims 5 to 6, characterized in that, The electrode assembly further includes a first adhesive tape, with each first leg corresponding to one first adhesive tape; the first adhesive tape is bonded to the first active layer and / or the current collector, and covers the first leg.

10. An electrochemical device, characterized in that, Includes the electrode assembly according to any one of claims 1 to 9.

11. An electronic device, characterized in that, Includes the electrochemical device according to claim 10.

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