Electrochemical devices and electronic devices

Abstract

The electrochemical device (100) comprises an electrode assembly (20) and a first conductive plate (30), the electrode assembly (20) comprises a first tab (21), the first tab (21) comprises a first current collector (210) and a first conductive material layer (211), the first current collector (210) comprises a first surface (210a), the first conductive material layer (211) is arranged on the first surface (210a), the first conductive material layer (211) is provided with a first opening (2110), the first surface (210a) comprises a first area (2100), the first area (2100) is configured as an area of the first surface (210a) exposed by the first opening (2110), and the first conductive plate (30) is connected to the first area (2100); from a first direction, the first tab (21) comprises a first end edge (213) and a second end edge (214), the first end edge (213) is provided with a first recess (2130); from the first direction, the first recess (2130) is arranged separately from the first area (2100), and the first recess (2130) overlaps the first area (2100) in a second direction; from the first direction, the first conductive plate (30) covers part of the first area (2100), part of the first conductive material layer (211) and part of the first recess (2130).

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to an electrochemical device and an electronic device having the electrochemical device. Background Art

[0002] Electrochemical devices (such as secondary batteries) are widely used in electronic products such as electronic mobile devices, power tools and electric vehicles, and people have increasingly higher requirements for the service life of electrochemical devices.

[0003] Electrochemical devices typically include an electrode assembly and a conductive plate electrically connected to the electrode assembly. When subjected to mechanical abuse (such as external compression or collision), protrusions on the conductive plate's surface (such as weld marks) can pierce the separator and cause a short circuit, shortening the device's lifespan. Summary of the Invention

[0004] Therefore, the present application proposes an electrochemical device capable of improving service life.

[0005] In addition, the present application also provides an electronic device having the electrochemical device.

[0006] In a first aspect, the present application provides an electrochemical device comprising an electrode assembly and a first conductive plate. The electrode assembly comprises a first electrode plate. The first electrode plate comprises a first current collector and a first conductive material layer. The first current collector comprises a first surface, and the first conductive material layer is provided on the first surface. The first conductive material layer is provided with a first opening. The first surface comprises a first region, and the first region is configured as the region of the first surface exposed by the first opening. The first conductive plate is connected to the first region. When viewed from a first direction, the first electrode plate comprises a first end edge and a second end edge arranged opposite to each other in a second direction, and the first electrode plate is provided with a first recess at the first end edge. When viewed from the first direction, the first recess is separated from the first region. When viewed from the second direction, the first recess overlaps with the first region. When viewed from the first direction, the first conductive plate covers a portion of the first region, the first conductive plate covers a portion of the first conductive material layer, and the first conductive plate covers a portion of the first recess. The first direction is perpendicular to the first region, and the second direction is perpendicular to the first direction.

[0007] After the first recess is provided in the present application, the position with the larger thickness in the first electrode sheet with the first conductive plate is the position of the first electrode sheet with double-sided coating on both sides of the first region when viewed from the first direction (hereinafter referred to as the first position), or the overlapping area between the first opening and the first recess and the first conductive plate (hereinafter referred to as the second position), which is conducive to reducing the total thickness of the electrochemical device in the first direction and improving space utilization. Moreover, in the event of mechanical abuse (such as external force impact or extrusion), if the position where the external force is applied overlaps with the protrusion (such as welding mark) on the surface of the first conductive plate, the position with the larger thickness in the first electrode sheet can bear part of the external force, reducing the possibility of the protrusion piercing the isolation membrane and causing a short circuit, thereby extending the service life of the electrochemical device. In addition, if the first electrode sheet is wrinkled or folded under the action of external force, the first recess can also provide a buffer space for the first conductive plate, reducing the possibility of the first conductive plate folding and breaking as the first electrode sheet folds, further extending the service life of the electrochemical device.

[0008] In some possible implementations, when viewed from the first direction, the first recess includes a first recess side and a second recess side disposed opposite each other in the third direction, and a third recess side connecting the first recess side and the second recess side. The first recess side, the second recess side, and the third recess side enclose the first recess. The third direction is perpendicular to both the first and second directions. The first recess of this structure can provide a larger buffer space for the first conductive plate in the event of mechanical abuse, further extending the service life of the electrochemical device.

[0009] In some possible implementations, when viewed from the first direction, the first end edge includes a first connecting edge connecting the first recessed edge. The third recessed edge and the first connecting edge both extend along the third direction. In the second direction, the distance from the first connecting edge to the third recessed edge is a first distance L1, and the distance from the third recessed edge to the first region is a second distance L2, wherein the first distance L1 is greater than the second distance L2. When the first distance L1 is larger, it is beneficial to increase the area of ​​the first recess, so that the first recess can provide a larger buffer space for the first conductive plate during mechanical abuse. When the second distance L2 is smaller (the first conductive material layer between the first opening and the first recess is covered by the first layer in some embodiments, making it difficult to play a capacity role, so when the second distance is reduced, the active material that is difficult to play a capacity role is reduced), under the condition that the size of the first electrode sheet along the second direction is constant, other active materials that can play a capacity role in the second direction increase, thereby reducing the impact on the capacity of the electrochemical device.

[0010] In some possible implementations, 1mm≤L1≤6mm, and 0.3mm≤L2≤4mm. By setting the range of the first distance L1, the first recess can provide a larger buffer space for the first conductive plate during mechanical abuse while also reducing the impact on the capacity of the electrochemical device. By setting the range of the second distance L2, the first conductive material layer located between the first opening and the first recess can effectively provide a cushioning effect while also reducing the impact on the capacity of the electrochemical device.

[0011] In some possible implementations, 0.1≤L2 / L1<1. By setting a lower limit for the ratio of the second distance L2 to the first distance L1, the impact on the capacity of the electrochemical device is reduced, and the portion of the first conductive material layer can effectively serve as a cushion.

[0012] In some possible implementations, when viewed from the first direction, the first recess further includes a fourth recess edge and a fifth recess edge. The fourth recess edge connects the first recess edge and the third recess edge, and the fifth recess edge connects the second recess edge and the third recess edge. The fourth recess edge is curved, and the fifth recess edge is curved. Thus, a smooth transition can be achieved between the first recess edge and the third recess edge, and between the second recess edge and the third recess edge. This helps reduce burrs generated at the transition locations during cutting of the first recess, thereby reducing the possibility of such burrs piercing the isolation membrane and causing a short circuit, thereby extending the service life of the electrochemical device. Furthermore, the area of ​​the first conductive material layer, which acts as a cushion between the first opening and the first recess, can be increased, which helps this portion of the first conductive material layer withstand external forces during mechanical abuse.

[0013] In some possible implementations, the thickness of the first conductive plate in the first direction is less than the thickness of the first conductive material layer. Therefore, the location of the first electrode sheet with the first conductive plate having the greater thickness is the first location. Therefore, in the event of mechanical abuse, if the location of the external force overlaps with a protrusion on the surface of the first conductive plate, the first location can preferentially bear part of the external force. Furthermore, when viewed from the first direction, the first location has a larger area than the second location, which facilitates bearing greater external forces during mechanical abuse and further extends the service life of the electrochemical device.

[0014] In some possible implementations, when viewed from the first direction, in the third direction, the distance from the first conductive plate to the edge of the first recess is a third distance L3, and the distance from the first conductive plate to the edge of the second recess is a fourth distance L4, and the third distance L3 is not equal to the fourth distance L4.

[0015] In some possible implementations, the first tab further includes a second layer of conductive material. The first current collector further includes a second surface disposed opposite to the first surface, and the second layer of conductive material is disposed on the second surface. The second layer of conductive material is provided with a second opening. The second surface includes a second region configured as a region of the second surface exposed by the second opening. The first region overlaps the second region in the first direction. The second region overlaps the first recess in the second direction. Thus, heat generated at the first conductive plate during charging of the electrochemical device can be conducted to the second region through the overlap of the first region and the second region and dissipated by the second region in addition to being dissipated through the first region exposed by the first region, reducing the possibility of local overheating of the first conductive plate.

[0016] In some possible implementations, the second region is disposed separately from the first recess in the second direction. Thus, the portion of the second layer of conductive material between the second opening and the first recess can also serve as a cushion in the first direction. When an external force acts on the back of the electrochemical device, the portion of the second layer of conductive material can also bear part of the external force, reducing the possibility of the protrusion on the surface of the first conductive plate piercing the separator and causing short circuit, and prolonging the service life of the electrochemical device.

[0017] In some possible implementations, the first region includes a first side and a second side disposed opposite to each other in the third direction as viewed in the first direction. The first side and the first recess side are located on a first side of the first conductive plate, and the second side and the second recess side are located on a second side of the first conductive plate opposite to the first side. The second region includes a third side and a fourth side disposed opposite to each other in the third direction as viewed in the first direction. The first side and the third side are located on the first side of the first conductive plate, and the second side and the fourth side are located on the second side of the first conductive plate. The first side and the third side are staggered as viewed in the first direction, and / or the second side and the fourth side are staggered as viewed in the first direction. Thus, the first tab has a thickness transition at positions corresponding to the first side and the third side, and / or the first tab has a thickness transition at positions corresponding to the second side and the fourth side. The thickness transition is advantageous in reducing the possibility of damage such as wrinkling of the first current collector during rolling, thereby reducing the possibility of appearance defects or internal interface defects of the electrochemical device. Furthermore, the thickness transition can also reduce the possibility of tearing of the first current collector when subjected to external force impact or extrusion. Thus, the service life of the electrochemical device is prolonged.

[0018] In some possible implementations, the second region completely covers the first region as viewed in the first direction. Thus, the protrusion of the first conductive plate can completely fall within the range of the second region as viewed in the first direction, reducing the possibility of the conductive material falling off when the protrusion falls on the second layer of conductive material and causing short circuit, and prolonging the service life of the electrochemical device.

[0019] In some possible implementations, the second region is adjacent to the first recess. Therefore, there is no second conductive material layer between the second region and the first recess, reducing the amount of conductive material (in some embodiments, this portion of conductive material is covered by the second layer, making it difficult for this portion of conductive material to function as a capacitor). Furthermore, the possibility of conductive material falling off and causing a short circuit when a protrusion on the surface of the first conductive plate lands on this portion of the second conductive material layer is reduced, thereby extending the service life of the electrochemical device.

[0020] In some possible implementations, the electrochemical device further includes a first layer comprising a first insulating material. The first layer is bonded to the first region. A first conductive plate is disposed between the first region and the first layer. The first layer can reduce the risk of protrusions on the surface of the first conductive plate piercing the isolation membrane and causing a short circuit.

[0021] In some possible implementations, the first layer completely covers the first opening and the first recess when viewed from the first direction, and extends beyond the first edge in the second direction. This allows the first layer to cover burrs generated at the first edge during the cutting process of the first current collector, thereby reducing the possibility of such burrs piercing the separator and causing a short circuit.

[0022] In some possible implementations, the first conductive plate is welded to the first region, thereby ensuring a high connection strength between the first conductive plate and the first region.

[0023] In some possible implementations, the electrode assembly is a wound structure, and the first electrode sheet is a positive electrode sheet.

[0024] The present application also provides an electronic device comprising the electrochemical device. The electronic device is powered by the electrochemical device, and the electrochemical device has a long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the overall structure of an electrochemical device provided in one embodiment of the present application.

[0026] Figure 2A for Figure 1 The electrochemical device is shown in a cross-sectional view along line II-II.

[0027] Figure 2B for Figure 2A An enlarged view of the electrode assembly of the electrochemical device at point A.

[0028] Figure 3 for Figure 2A A front view of the first pole piece of the electrode assembly is shown in some embodiments.

[0029] Figure 4 for Figure 3 A back view of the first pole piece is shown.

[0030] Figure 5 for Figure 3 The front view of the first pole piece with the first layer removed is shown.

[0031] Figure 6 for Figure 3 The front views of other embodiments of the first pole piece are shown.

[0032] Figure 7A for Figure 3 The front views of other embodiments of the first pole piece are shown.

[0033] Figure 7B for Figure 3 The front views of other embodiments of the first pole piece are shown.

[0034] Figure 8 for Figure 3 The front views of other embodiments of the first pole piece are shown.

[0035] Figure 9 for Figure 3 The front views of other embodiments of the first pole piece are shown.

[0036] Figure 10A for Figure 3 The illustrated cross-sectional view of the first pole piece along line XX in some embodiments.

[0037] Figure 10B for Figure 3 The first pole piece shown is a cross-sectional view taken along XX in some other embodiments.

[0038] Figure 11 for Figure 3 The cross-sectional view of the first pole piece along XI-XI is shown.

[0039] Figure 12 for Figure 3 The cross-sectional view of the first pole piece along line XII-XII is shown.

[0040] Figure 13 for Figure 3 The front views of other embodiments of the first pole piece are shown.

[0041] Figure 14 for Figure 3 The front views of other embodiments of the first pole piece are shown.

[0042] Figure 15 This is a back view of a first electrode in an electrochemical device provided in another embodiment of the present application.

[0043] Figure 16 for Figure 15 The cross-sectional view of the first pole piece along XVI-XVI is shown.

[0044] Figure 17 An overall structure schematic of an electronic device according to an embodiment of the present application.

[0045] Explanation of main component symbols

[0046] Electronic device 1

[0047] Housing 10

[0048] Electrode assembly 20

[0049] First electrode sheet 21

[0050] Second electrode sheet 22

[0051] Separator 23

[0052] First conductive plate 30

[0053] Protrusions 30a, 30b, 210d

[0054] Depressions 30c, 210c

[0055] First side 30A

[0056] Second side 30B

[0057] Third side 30C

[0058] Fourth side 30D

[0059] First connection region 31

[0060] Second connection region 32

[0061] Third connection region 33

[0062] Second conductive plate 40

[0063] First layer 50

[0064] First edge 51

[0065] Second edge 52

[0066] Third edge 53

[0067] Fourth edge 54

[0068] Second layer 60

[0069] Electrochemical device 100

[0070] First wall 111

[0071] Second wall 112

[0072] First current collector 210

[0073] First surface 210a

[0074] Second surface 210b

[0075] First conductive material layer 211

[0076] Second conductive material layer 212

[0077] First end edge 213

[0078] First connecting edge 213a

[0079] Second connecting edge 213b

[0080] Second end edge 214

[0081] Second current collector 220

[0082] The third surface 220a

[0083] Fourth surface 220b

[0084] The third conductive material layer 221

[0085] Fourth conductive material layer 222

[0086] First Area 2100

[0087] Second area 2100'

[0088] First side 2101

[0089] Second side 2102

[0090] The Fifth Side

[0091] The Sixth Side

[0092] The third side 2105

[0093] The fourth side 2106

[0094] The Seventh Side 2107

[0095] The Eighth Side 2108

[0096] First opening 2110

[0097] Second opening 2120

[0098] first recess 2130

[0099] First concave side 2131

[0100] Second concave side 2132

[0101] The third concave side 2133

[0102] Fourth concave side 2134

[0103] Fifth concave side 2135

[0104] Winding center axis C

[0105] Winding direction D

[0106] First direction D1

[0107] Second direction D2

[0108] Third direction D3

[0109] First position P1

[0110] Second position P2

[0111] Thickness T1, T2

[0112] First distance L1

[0113] Second distance L2

[0114] The third distance L3

[0115] Fourth distance L4

[0116] Fifth distance L5

[0117] Sixth distance L6

[0118] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0119] The technical solutions in the embodiments of the present application are described clearly and in detail below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present application. The terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0120] Below, embodiments of the present application will be described in detail. However, the present application may be embodied in many different forms and should not be construed as limited to the exemplary embodiments illustrated herein. Rather, these exemplary embodiments are provided to make the present application thorough and detailed for those skilled in the art.

[0121] In addition, for simplicity and clarity, the figures depict the relative spacing and arrangement of various components, layers, and / or regions as may be desired for the purposes of this disclosure. Throughout this document, the same numbers are used to indicate the same components. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. In addition, it should be understood that any reference to an element herein using a designation including relating term, such as "connecting" can refer to a direct connection between the elements, or can refer to an indirect connection between the elements through an intervening element.

[0122] Further, use of "may" when describing embodiments of the application means that one or more embodiments of the application "can" include the recited feature but not necessarily.

[0123] The specific terminology used herein is for the purpose of describing specific embodiments and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0124] Spatially relative terms, such as "up", "down", and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device or apparatus in use or operation in addition to the orientations depicted in the figures. For example, if a device or apparatus in the figures is turned over, elements described as "above" or "up" other elements or features would then be oriented "below" or "down" the other elements or features. Thus, the exemplary term "above" can encompass both an orientation that is above as well as below. It will be understood that, although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the exemplary embodiments.

[0125] In this application, numbers used to express amounts, ratios, and / or other quantities are intended to be approximate.

[0126] See Figure 1 and Figure 2AIn one embodiment of the present application, an electrochemical device 100 is provided, comprising a housing 10, an electrode assembly 20, a first conductive plate 30, and a second conductive plate 40. The electrode assembly 20 is located in the housing 10. The first conductive plate 30 and the second conductive plate 40 are both electrically connected to the electrode assembly 20, and extend out of the housing 10 from the interior of the housing 10. The housing 10 may be a packaging bag encapsulated by a packaging film (such as an aluminum-plastic film), that is, the electrochemical device 100 may be a soft-pack battery. In other embodiments, the electrochemical device 100 is not limited to a soft-pack battery, and may also be a steel-shell battery or an aluminum-shell battery. Figure 2A The number of electrode assemblies 20 shown is one. In other embodiments, the number of electrode assemblies 20 may also be multiple, and the multiple electrode assemblies 20 are located in the housing 10 and are electrically connected in parallel or in series.

[0127] like Figure 2A As shown, the electrode assembly 20 may be a wound structure. The electrode assembly 20 includes a first electrode sheet 21, a second electrode sheet 22, and a separator 23, wherein the separator 23 is disposed between the first electrode sheet 21 and the second electrode sheet 22. The first electrode sheet 21, the separator 23, and the second electrode sheet 22 are sequentially stacked and wound to form the electrode assembly 20. Figure 2A As shown, the electrode assembly 20 has a winding center axis C perpendicular to the paper. The winding direction D is Figure 2A The direction of counterclockwise rotation around the winding center axis C is shown. In other embodiments, the winding direction D can also be a clockwise rotation direction. In the present application, a three-dimensional coordinate system is established based on a first direction D1, a second direction D2, and a third direction D3 that are perpendicular to each other. The first direction D1 is a direction perpendicular to a surface of the first conductive plate 30. The second direction D2 is a direction in which the first conductive plate 30 protrudes from the electrode assembly 20, and in some embodiments, is also the direction of the winding center axis C. The third direction D3 is a direction from the first conductive plate 30 to the second conductive plate 40. In other embodiments, the electrode assembly 20 can also be a laminated structure.

[0128] like Figure 2A and Figure 2B As shown, the first electrode 21 includes a first current collector 210, a first conductive material layer 211 and a second conductive material layer 212. The first current collector 210 includes a first surface 210a and a second surface 210b that are opposite to each other. The first conductive material layer 211 is provided on the first surface 210a, and the second conductive material layer 212 is provided on the second surface 210b. Figure 2AAs shown, the second tab 22 includes a second current collector 220, a third conductive material layer 221, and a fourth conductive material layer 222. The second current collector 220 includes oppositely disposed third and fourth surfaces 220a and 220b, the third conductive material layer 221 is disposed on the third surface 220a, and the fourth conductive material layer 222 is disposed on the fourth surface 220b. The second conductive material layer 212 and the fourth conductive material layer 222 face each other through the separator 23. In some embodiments, as shown, the second conductive material layer 212 and the fourth conductive material layer 222 are disposed on the same side of the separator 23. In other embodiments, the second conductive material layer 212 and the fourth conductive material layer 222 are disposed on opposite sides of the separator 23. Figure 2A As shown, after the lamination and winding, the first surface 210a of the first current collector 210 is farther from the winding center axis C than the second surface 210b, and the third surface 220a of the second current collector 220 is farther from the winding center axis C than the fourth surface 220b. It can be understood that in other embodiments, the first surface 210a of the first current collector 210 can also be closer to the winding center axis C than the second surface 210b, and the third surface 220a of the second current collector 220 can also be closer to the winding center axis C than the fourth surface 220b. In some embodiments, in the first direction D1, the thickness of the first current collector 210 can range from 3 μm to 20 μm, the thickness of the first conductive material layer 211 can range from 30 μm to 300 μm, and the thickness of the second conductive material layer 212 can range from 30 μm to 300 μm.

[0129] The first tab 21 can be a positive electrode tab or a negative electrode tab. Correspondingly, the first current collector 210 can be a positive current collector or a negative current collector, and the first conductive material layer 211 and the second conductive material layer 212 can both be positive active material layers or negative active material layers. The second tab 22 can be a negative electrode tab or a positive electrode tab. Correspondingly, the second current collector 220 can be a negative current collector or a positive current collector, and the third conductive material layer 221 and the fourth conductive material layer 222 can both be negative active material layers or positive active material layers. In some embodiments, the first tab 21 is a positive electrode tab, and the second tab 22 is a negative electrode tab. The positive current collector can be made of an aluminum foil or a nickel foil, and the negative current collector can be made of at least one of a copper foil, a nickel foil, or a carbon-based current collector.

[0130] The positive active material layer contains a positive active material, which includes a compound that reversibly intercalates and deintercalates lithium ions (i.e., a lithiated intercalation compound). In some embodiments, the positive active material can include a lithium transition metal composite oxide. The lithium transition metal composite oxide contains lithium and at least one element selected from cobalt, manganese, and nickel. In some embodiments, the positive active material is selected from at least one of lithium cobaltate (LiCoO2), lithium nickel manganese cobalt ternary material (NCM), lithium manganate (LiMn2O4), lithium nickel manganate (LiNi 0.5 Mn 1.5 O4), or lithium iron phosphate (LiFePO4).

[0131] The negative electrode active material layer contains a negative electrode active material, which is a negative electrode active material known in the art that can reversibly deintercalate active ions, and is not limited in this application. For example, it can be a combination of one or more of graphite, soft carbon, hard carbon, carbon fiber, mesophase carbon microspheres, silicon-based materials, tin-based materials, lithium titanate or other metals that can form alloys with lithium. Among them, graphite can be selected from a combination of one or more of artificial graphite, natural graphite and modified graphite; silicon-based materials can be selected from a combination of one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, and silicon alloys; tin-based materials can be selected from a combination of one or more of elemental tin, tin oxide compounds, and tin alloys.

[0132] The isolation film 23 includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid. For example, the polyethylene includes at least one selected from high-density polyethylene, low-density polyethylene, or ultra-high molecular weight polyethylene. Polyethylene and polypropylene have a good effect on improving short circuits and can improve the stability of electrochemical devices through the shutdown effect.

[0133] Please refer to Figure 3 and Figure 5 The first conductive material layer 211 includes a first opening 2110. The first surface 210a of the first current collector 210 includes a first region 2100. The first region 2100 is configured as the region where the first surface 210a is exposed from the first opening 2110. That is, the first region 2100 is exposed from the first opening 2110. In this case, the first direction D1 is also perpendicular to the first region 2100. In this application, laser cleaning can be used to clean the first conductive material layer 211 to create the first opening 2110, thereby exposing the first region 2100. Alternatively, foam glue can be pre-applied to the first region 2100, and then the active material is applied and then heated to remove the foam glue, thereby exposing the first region 2100. Alternatively, the active material on the first region 2100 can be directly scraped off with a scraper, thereby exposing the first region 2100. However, it is understood that a small amount of active material may remain on the surface of the first region 2100 after laser cleaning or scraping, and this is not a limitation of this application.

[0134] In some embodiments, the first region 2100 and the first opening 2110 may both be rectangular when viewed from the first direction D1. Specifically, the first region 2100 includes a first side 2101 and a second side 2102 disposed opposite each other in the third direction D3, and a fifth side 2103 and a sixth side 2104 disposed opposite each other in the second direction D2. The fifth side 2103 connects the first side 2101 and the second side 2102, and the sixth side 2104 connects the first side 2101 and the second side 2102. In some embodiments, the first side 2101 and the second side 2102 may both extend along the second direction D2, the fifth side 2103 and the sixth side 2104 may both extend along the third direction D3, and the first side 2101, the second side 2102, the fifth side 2103, and the sixth side 2104 may all be straight lines. In other embodiments, when the first region 2100 is formed using methods such as laser cleaning, at least one of the first side 2101, the second side 2102, the fifth side 2103, and the sixth side 2104 may also include a concave-convex shape, which is not limited in this application. It is understood that the first opening 2110 is a three-dimensional structure, but the first opening 2110 includes multiple edges connected in sequence when viewed from the first direction D1 (not shown in the figure). When viewed from the first direction D1, the first side 2101, the second side 2102, the fifth side 2103, and the sixth side 2104 of the first region 2100 respectively coincide with the multiple edges of the first opening 2110.

[0135] When viewed from the first direction D1, the first conductive plate 30 is connected to the first region 2100. A first side 30A of the first conductive plate 30 is defined as a position located on one side of the first conductive plate 30 in the third direction D3 when viewed from the first direction D1. A second side 30B of the first conductive plate 30 is defined as a position opposite to the first side 30A and located on the other side of the first conductive plate 30 in the third direction D3 when viewed from the first direction D1. A third side 30C of the first conductive plate 30 is defined as a position located on one side of the first conductive plate 30 in the second direction D2 when viewed from the first direction D1. A fourth side 30D of the first conductive plate 30 (in the Figure 1 ) is opposite to the third side 30C and is located on the other side of the first conductive plate 30 in the second direction D2 when viewed from the first direction D1. Figure 3 and Figure 5As shown, the first side 30A of the first conductive plate 30 may refer to the left side of the first conductive plate 30, the second side 30B of the first conductive plate 30 may refer to the right side of the first conductive plate 30, the third side 30C of the first conductive plate 30 may refer to the bottom side of the first conductive plate 30, and the fourth side 30D of the first conductive plate 30 may refer to the top side of the first conductive plate 30. The third side 30C of the first conductive plate 30 is located inside the housing 10, and the fourth side 30D is located outside the housing 10. As viewed from the first direction D1, in the third direction D3, the first side 2101 is located on the first side 30A of the first conductive plate 30, and the second side 2102 is located on the second side 30B of the first conductive plate 30, which is opposite to the first side 30A. As viewed from the first direction D1, the first conductive plate 30 partially covers the fifth side 2103, and the first conductive plate 30 and the fifth side 2103 partially overlap. In order to meet the high current charging requirement of the electrochemical device 100 , the first region 2100 may be provided in a region of the first electrode sheet 21 excluding the winding head and the winding tail.

[0136] In some embodiments, the first conductive plate 30 is welded to the first region 2100, thereby providing a high connection strength between the first conductive plate 30 and the first region 2100. Figure 10A In some embodiments, at least one protrusion 30a may be formed at the welding point between the first conductive plate 30 and the first region 2100. For example, a plurality of protrusions 30a arranged in a matrix may be formed at the welding point between the first conductive plate 30 and the first region 2100, and the protrusions 30a protrude from the first region 2100 toward the first conductive plate 30. At the same time, at least one protrusion 30b is correspondingly formed on the surface of the first conductive plate 30 facing away from the first region 2100. At least one recess 210c is correspondingly formed on the second surface 210b of the first current collector 210. The protrusions 30a and 30b and the recess 210c may be formed during the welding process (which may be referred to as weld marks), but this application does not limit this. Please refer to Figure 10B In other embodiments, at least one depression 30c may be formed at the weld between the first conductive plate 30 and the first region 2100. For example, a plurality of depressions 30c arranged in a matrix may be formed at the weld between the first conductive plate 30 and the first region 2100. The depressions 30c are recessed from the first region 2100 toward the first conductive plate 30. Simultaneously, at least one depression 30d is formed on the surface of the first conductive plate 30 facing away from the first region 2100, and at least one protrusion 210d is formed on the second surface 210b of the first current collector 210. The depressions 30c and 30d, as well as the protrusion 210d, may be formed during the welding process (which may be referred to as weld marks), but this application is not limited thereto. In other embodiments, the first conductive plate 30 may be connected to the first region 2100 using conductive adhesive or other methods. In the first direction D1, the thickness of the first conductive plate 30 may range from 10 μm to 150 μm, and the thickness of the second conductive plate 40 may range from 10 μm to 150 μm.

[0137] As shown in Figure 3 and Figure 5 viewed from the first direction D1, the first pole piece 21 includes a first end edge 213 and a second end edge 214 oppositely arranged in the second direction D2. In the second direction D2, the second end edge 214, the sixth edge 2104, the fifth edge 2103 and the first end edge 213 are sequentially arranged. Among them, the second end edge 214, the sixth edge 2104, the fifth edge 2103 and the first end edge 213 are sequentially arranged in the second direction D2, which means that a certain virtual straight line arranged in the second direction D2 passes through the second end edge 214, the sixth edge 2104, the fifth edge 2103 and the first end edge 213 in turn. The first end edge 213 and the second end edge 214 can both extend along the third direction D3. The first pole piece 21 is provided with a first recess 2130 at the first end edge 213. Among them, the first recess 2130 can be cut by laser cutting or die cutting. Viewed from the first direction D1, the first opening 2110 is arranged separately from the first recess 2130, so that there is a part of the first conductive material layer 211 between the first opening 2110 and the first recess 2130. Viewed from the first direction D1, the first opening 2110 can be arranged separately from the second end edge 214. Viewed from the second direction D2, the first region 2100 overlaps the first recess 2130. Here, overlap means that at least part of them is covered in a certain direction. For example, as shown in Figures 3 to 5 viewed from the second direction D2, the first recess 2130 covers part of the first region 2100; again, as shown in Figure 6As shown, in other embodiments, when viewed from the second direction D2, the first recess 2130 completely covers the first region 2100, and the first region 2100 also completely covers the first recess 2130 in the second direction D2 (i.e., the two overlap). When viewed from the first direction D1, the first conductive plate 30 covers a portion of the first region 2100, and also covers a portion of the first conductive material layer 211 (i.e., the portion of the first conductive material layer 211 between the first opening 2110 and the first recess 2130). The first conductive plate 30 also covers a portion of the first recess 2130. Specifically, the first conductive plate 30 includes a first connection region 31, a second connection region 32, and a third connection region 33, which are sequentially connected in the second direction D2. When viewed from the first direction D1, the first connection region 31 covers a portion of the first region 2100, and a weld mark may be formed in the first connection region 31; the second connection region 32 covers a portion of the first conductive material layer 211; and the third connection region 33 covers a portion of the first recess 2130. The third connection area 33 extends in the second direction D2 beyond the first end edge 213 and further out of the housing 10. The first connection area 31 is where the current flows when the electrochemical device 100 is charged. The heat generated in the first connection area 31 during charging of the electrochemical device 100 can be dissipated through the first area 2100 exposed to the first connection area 31. Figure 11 and Figure 12 It can be understood that the portion of the first conductive material layer 211 between the first opening 2110 and the first recess 2130 can function as a cushion in the first direction D1. The presence of this portion of the first conductive material layer 211 reduces the height difference with the weld mark (such as the protrusion 30b) in the first direction D1. This portion of the first conductive material layer 211 can even be higher than the weld mark in the first direction D1. Therefore, in the event of mechanical abuse, if the external force acting on the position overlaps with the weld mark of the first conductive plate 30, especially when the external force acts on the front surface of the electrochemical device 100 (i.e., Figure 2A When the shell 10 is shown facing the first wall 111 of the first area 2100, the portion of the first conductive material layer 211 that acts as a cushion can bear part of the external force, reducing the possibility of the weld mark piercing the isolation membrane 23 and contacting the second electrode 22 to cause a short circuit, thereby extending the service life of the electrochemical device 100.

[0138] like Figure 3 and Figure 5As shown, in some embodiments, the first recessed portion 2130 includes a first recessed portion edge 2131, a second recessed portion edge 2132, and a third recessed portion edge 2133. The first recessed portion edge 2131 and the second recessed portion edge 2132 are arranged opposite each other in the third direction D3. The first recessed portion edge 2131 and the second recessed portion edge 2132 may both extend along the second direction D2, and the third recessed portion edge 2133 may extend along the third direction D3. When the first recessed portion edge 2131 extends along the second direction D2, the first recessed portion edge 2131 may be parallel to the second direction D2 or may be inclined relative to the second direction D2 (i.e., the angle between the first recessed portion edge 2131 and the second direction D2 is less than 90°). However, the first recessed portion edge 2131 as a whole is not parallel to the third direction D3. The same applies to the second recessed portion edge 2132 extending along the second direction D2. The third recessed portion edge 2133 connects the first recessed portion edge 2131 and the second recessed portion edge 2132. The first recessed portion 2130 is formed by a first recessed portion side 2131, a second recessed portion side 2132, and a third recessed portion side 2133. When viewed from the first direction D1, the first opening 2110 is separated from the third recessed portion side 2133 of the first recessed portion 2130. When viewed from the first direction D1, the first side 2101 and the first recessed portion side 2131 are both located on the first side 30A of the first conductive plate 30, the second side 2102 and the second recessed portion side 2132 are both located on the second side 30B of the first conductive plate 30, and the first conductive plate 30 partially covers the third recessed portion 2133. In some specific embodiments, when viewed from the first direction D1, the first recessed portion 2130 may be substantially rectangular, with the first recessed portion side 2131, the second recessed portion side 2132, and the third recessed portion side 2133 being straight lines. When viewed from the first direction D1 , the virtual boundary line between the first connection area 31 and the second connection area 32 overlaps with the fifth side 2103 , and the virtual boundary line between the second connection area 32 and the third connection area 33 overlaps with the third recess side 2133 .

[0139] Furthermore, when viewed from the first direction D1, the first end edge 213 includes a first connecting edge 213a connecting to the first recessed edge 2131 and a second connecting edge 213b connecting to the second recessed edge 2132. Both the first connecting edge 213a and the second connecting edge 213b may extend along the third direction D3. When viewed from the first direction D1, the first connecting edge 213a is located on the first side 30A of the first conductive plate 30, and the second connecting edge 213b is located on the second side 30B of the first conductive plate 30.

[0140] like Figure 7AAs shown, in other embodiments, the shape of the first recess 2130 can be varied. For example, when viewed from the first direction D1, the first recess 2130 can be substantially U-shaped. In this case, the first recess 2130 includes a first recess side 2131, a second recess side 2132, a third recess side 2133, a fourth recess side 2134, and a fifth recess side 2135. The first recess side 2131 and the second recess side 2132 are arranged opposite each other in the third direction D3. The first recess side 2131 and the second recess side 2132 can both extend along the second direction D2, and the third recess side 2133 can extend along the third direction D3. The fourth recess side 2134 connects the first recess side 2131 and the third recess side 2133 and is curved. The fifth recess side 2135 connects the second recess side 2132 and the third recess side 2133 and is curved. The first recessed portion 2130 is formed by the first recessed portion edge 2131, the second recessed portion edge 2132, the third recessed portion edge 2133, the fourth recessed portion edge 2134, and the fifth recessed portion edge 2135. In some specific embodiments, the first recessed portion edge 2131, the second recessed portion edge 2132, and the third recessed portion edge 2133 are all straight lines, while the fourth recessed portion edge 2134 and the fifth recessed portion edge 2135 are both arc-shaped and protrude away from the first recessed portion 2130. In other embodiments, the third recessed portion edge 2133 may also be arc-shaped. By providing the curved fourth recessed portion edge 2134 and the fifth recessed portion edge 2135, a smooth transition is achieved between the first recessed portion edge 2131 and the third recessed portion edge 2133, and between the second recessed portion edge 2132 and the third recessed portion edge 2133. This helps reduce burrs generated during the cutting of the first recess 2130 at the transition location, thereby reducing the possibility of such burrs piercing the separator 23 and causing a short circuit with the second electrode 22, thereby extending the service life of the electrochemical device 100. Furthermore, by providing the curved fourth recess edge 2134 and fifth recess edge 2135, the area of ​​the first conductive material layer 211, which acts as a cushion between the first opening 2110 and the first recess 2130, is increased, which helps this portion of the first conductive material layer 211 withstand external forces during mechanical abuse.

[0141] like Figure 7BAs shown, in other embodiments, the first recessed edge 2131 can be curved, and the second recessed edge 2132 can also be curved. In some specific embodiments, the first recessed edge 2131 is an arc convexly disposed away from the first recessed portion 2130. The second recessed edge 2132 is also an arc convexly disposed away from the first recessed portion 2130. In this case, a smooth transition can also be achieved between the first recessed edge 2131 and the third recessed edge 2133, and between the second recessed edge 2132 and the third recessed edge 2133. This helps to reduce burrs generated at the transition position during the cutting process of the first recessed portion 2130, thereby reducing the possibility of the burrs piercing the isolation membrane 23 and contacting the second electrode 22 to cause a short circuit, thereby extending the service life of the electrochemical device 100.

[0142] like Figure 8 As shown, in other embodiments, when viewed from the first direction D1, the first recess 2130 may also be substantially V-shaped. In this case, the first recess 2130 includes only a first recess side 2131 and a second recess side 2132. The first recess side 2131 and the second recess side 2132 may both extend away from the second direction D2. The first recess side 2131 is directly connected to the second recess side 2132, and the first recess side 2131 and the second recess side 2132 enclose the first recess 2130. In some specific embodiments, the first recess side 2131 and the second recess side 2132 are both straight lines.

[0143] See also Figure 4 In some embodiments, the second surface 210b of the first current collector 210 includes a second region 2100'. The second conductive material layer 212 includes a second opening 2120. The second region 2100' is configured as the region where the second surface 210b is exposed from the second opening 2120. That is, the second region 2100' is exposed from the second opening 2120. When viewed from the first direction D1, the first region 2100 and the second region 2100' overlap. Therefore, during charging of the electrochemical device 100, heat generated by the first conductive plate 30 can be dissipated not only through the first region 2100 exposed in the first connection region 31 but also through conduction to the second region 2100' through the overlap between the first and second regions 2100 and 2100', where it can be dissipated, thereby reducing the possibility of localized overheating of the first conductive plate 30. When viewed from the second direction D2, the second region 2100' overlaps the first recess 2130.

[0144] In some embodiments, the second region 2100' may be adjacent to the first recess 2130. Therefore, when viewed from the first direction D1, no second conductive material layer 212 exists between the second region 2100' and the first recess 2130. Therefore, the first electrode 21 located between the first opening 2110 and the first recess 2130 is a single-sided coating region.

[0145] In some embodiments, when viewed from the first direction D1, the second area 2100' and the second opening 2120 may both be rectangular. The second area 2100' includes a third side 2105 and a fourth side 2106 disposed opposite to each other in the third direction D3, and a seventh side 2107 and an eighth side 2108 disposed opposite to each other in the second direction D2. The seventh side 2107 is connected between the third side 2105 and the fourth side 2106, and the eighth side 2108 is connected between the third side 2105 and the fourth side 2106. The third side 2105 and the fourth side 2106 may both extend along the second direction D2, and the seventh side 2107 and the eighth side 2108 may both extend along the third direction D3. Figures 3 to 5 As shown, when viewed from the first direction D1, the first side 2101 and the third side 2105 are located on the first side 30A of the first conductive plate 30, and the second side 2102 and the fourth side 2106 are located on the second side 30B of the first conductive plate 30. When viewed from the first direction D1, the first conductive plate 30 covers the seventh side 2107. When viewed from the first direction D1, the sixth side 2104 and the eighth side 2108 may overlap; in other embodiments, such as Figure 9 As shown, the sixth side 2104 and the eighth side 2108 may also be staggered with each other in the second direction D2. Figures 3 to 5 As shown, the sixth side 2104 overlaps with the eighth side 2108. The second area 2100' is connected to the first recess 2130, so the fifth side 2103 and the seventh side 2107 are staggered with each other in the second direction D2, and the seventh side 2107 is closer to the first end side 213 than the fifth side 2103. Observed from the first direction D1, the seventh side 2107 overlaps with the third recess side 2133. Therefore, in the second direction D2, the second end side 214, the eighth side 2108, the fifth side 2103, the seventh side 2107 (the third recess side 2133) and the first end side 213 are arranged in sequence. Since there is no second conductive material layer 212 between the second area 2100' and the first recess 2130, the amount of conductive material used is reduced. In addition, the weld mark (such as Figure 10A The recess 210c shown or Figure 10B The protrusion 210d shown extends beyond the fifth edge 2103 and lands on that portion of the second conductive material layer 212, thereby reducing the possibility of conductive material falling off and causing a short circuit, thereby extending the service life of the electrochemical device 100. It will be understood that the second opening 2120 is a three-dimensional structure. However, when viewed from the first direction D1, the second opening 2120 includes multiple sequentially connected edges (not shown). When viewed from the first direction D1, the third edge 2105, fourth edge 2106, seventh edge 2107, and eighth edge 2108 of the second region 2100' respectively coincide with multiple edges of the second opening 2120.

[0146] It can be understood that if the first recess 2130 is not provided, after the first conductive plate 30 is connected to the first region 2100, the position with the larger thickness in the first pole piece 21 with the first conductive plate 30 should be the overlapping region of the first conductive material layer 211, the first current collector 210, the second conductive material layer 212 and the first conductive plate 30 when viewed from the first direction D1 (including the sum of the thicknesses of the first conductive plate 30, the first conductive material layer 211, the first current collector 210 and the second conductive material layer 212).

[0147] like Figures 10A to 12 As shown, after the first recess 2130 is provided in the present application, the position with the larger thickness in the first electrode piece 21 with the first conductive plate 30 should be the position of the first electrode piece 21 with double-sided coating located on both sides of the first area 2100 in the third direction D3 when viewed from the first direction D1 (hereinafter referred to as: first position P1, the thickness T1 of the first position P1 includes the sum of the thicknesses of the first conductive material layer 211, the first current collector 210 and the second conductive material layer 212), or, the overlapping area between the first opening 2110 and the first recess 2130 and the first conductive plate 30 (hereinafter referred to as: second position P2, the thickness T2 of the second position P2 includes the sum of the thicknesses of the first conductive plate 30, the first conductive material layer 211 and the first current collector 210).

[0148] Therefore, the present application is conducive to reducing the total thickness of the electrochemical device 100 in the first direction D1 and improving space utilization by providing the first recess 2130. Moreover, in the event of mechanical abuse, if the position where the external force acts overlaps with the weld mark of the first conductive plate 30, especially when the external force acts on the front of the electrochemical device 100, the first position P1 or the second position P2 with a larger thickness in the first electrode 21 can bear part of the external force, reducing the possibility of the weld mark (such as the protrusion 30b) piercing the isolation membrane 23 and short-circuiting with the second electrode 22, thereby extending the service life of the electrochemical device 100. In addition, the first electrode 21 may wrinkle under the action of external force, causing the first end edge 213 or the second end edge 214 of the first electrode 21 to fold toward the middle of the first electrode 21. At this time, the first recess 2130 can provide a buffer space for the third connection area 33 of the first conductive plate 30, reducing the possibility of the first conductive plate 30 folding and breaking along with the first electrode 21, further extending the service life of the electrochemical device 100. Especially as Figure 3 、 Figure 7A and Figure 7B As shown, when the first recess 2130 includes a first recess side 2131 , a second recess side 2132 and a third recess side 2133 , the first recess 2130 of the above structure can provide a larger buffer space for the first conductive plate 30 during mechanical abuse.

[0149] In some embodiments, the second electrode sheet 22 may also adopt a design similar to that of the first electrode sheet 21. For example, a third region (e.g., a blank region) may be provided on the second current collector 220 of the second electrode sheet 22 to connect to the second conductive plate 40, a second recess may be provided at an end edge of the second electrode sheet 22, and the third region of the third conductive material layer 221 corresponding to the blank region may be separated from the first recess 2130 in the second direction D2. In this way, the space utilization of the electrochemical device 100 may be further improved, and the service life may be extended.

[0150] like Figures 10A to 12 As shown, in some embodiments, the thickness of the first conductive plate 30 in the first direction D1 is less than the thickness of the first conductive material layer 211. Therefore, after the first conductive plate 30 is connected to the first region 2100, the locations of the first electrode piece 21 with the first conductive plate 30 having the thickest thickness are the locations of the first electrode piece 21 with the double-sided coating located on both sides of the first region 2100 in the third direction D3, i.e., the first locations P1. Therefore, in the event of mechanical abuse, if the location of the external force overlaps with the weld mark of the first conductive plate 30, the first locations P1 can preferentially bear part of the external force. Furthermore, when viewed from the first direction D1, the first locations P1 have a larger area than the second locations P2. This facilitates bearing greater external forces during mechanical abuse, further extending the service life of the electrochemical device 100.

[0151] like Figure 3 、 Figures 10A to 12 As shown, in some embodiments, the electrochemical device 100 further includes a first layer 50 comprising an insulating material. The first layer 50 is bonded to the first region 2100. The first conductive plate 30 is disposed between the first region 2100 and the first layer 50. The first layer 50 is used to cover the weld marks (such as the protrusions 30b) of the first conductive plate 30, thereby reducing the risk of the weld marks piercing the isolation membrane 23 and causing a short circuit. The first layer 50 may be a single-sided adhesive or a double-sided adhesive, and the specific material may be selected from at least one of polypropylene, polyethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, or polyethylene glycol. In other embodiments, the first layer 50 may also be a ceramic coating. In the first direction D1, the thickness of the first layer 50 may range from 3 μm to 30 μm.

[0152] In some embodiments, when viewed from the first direction D1, the first layer 50 completely covers the first opening 2110 and the first recess 2130, and also covers the first conductive material layer 211 located between the first opening 2110 and the first recess 2130. Furthermore, the first layer 50 extends beyond the first end edge 213 in the second direction D2. Specifically, when viewed from the first direction D1, the first layer 50 includes a first edge 51 and a second edge 52 disposed opposite each other in the second direction D2, and also includes a third edge 53 and a fourth edge 54 disposed opposite each other in the third direction D3. The first edge 51 and the second edge 52 may both extend along the third direction D3. The third edge 53 and the fourth edge 54 may both extend along the third direction D3. The third edge 53 is connected between the first edge 51 and the second edge 52, and the fourth edge 54 is connected between the first edge 51 and the second edge 52. The first edge 51 extends beyond the first end edge 213 in the second direction D2. When viewed from the first direction D1, the second edge 52 may be located between the sixth edge 2104 and the second end edge 214. The third edge 53 is located on the first side 30A of the first conductive plate 30, and in the third direction D3, the first side 2101 is located between the third edge 53 and the first conductive plate 30. The fourth edge 54 may be located on the second side 30B of the first conductive plate 30, and in the third direction D3, the second side 2102 is located between the fourth edge 54 and the first conductive plate 30. In this way, the first layer 50 can also cover the burrs generated at the first end edge 213 of the first current collector 210 during the cutting process, thereby reducing the possibility of the burrs piercing the isolation film 23 and contacting the second pole piece 22 to short-circuit. When viewed from the first direction D1, the first layer 50 can also cover a portion of the first conductive material layer 211. For ease of distinction, Figure 3 The first conductive material layer 211 covered by the first layer 50 is shown as being filled in a different manner than the other first conductive material layers 211. However, it is understood that this does not mean that the first conductive material layer 211 covered by the first layer 50 and the other first conductive material layers 211 are made of different active materials, and there is no clear boundary between the two. It is understood that, as Figure 7A As shown, when the curved fourth recess edge 2134 and the fifth recess edge 2135 are set, the area of ​​the first conductive material layer 211 that acts as a cushion between the first opening 2110 and the first recess 2130 is increased, which is also beneficial to increasing the contact area between the first layer 50 and the first conductive material layer 211, and improving the connection strength of the first layer 50 on the first pole piece 21.

[0153] like Figure 5 、 Figures 10A to 12As shown, electrochemical device 100 further includes a second layer 60 comprising an insulating material. Second layer 60 is bonded to second region 2100'. Second layer 60 is used to cover weld marks (e.g., protrusion 210d), thereby reducing the risk of such weld marks piercing separator 23 and causing a short circuit. In some embodiments, second layer 60 may be single-sided tape, double-sided tape, or a ceramic coating.

[0154] like Figure 3 and Figure 5 As shown, in some embodiments, in the second direction D2, the distance between the first connecting edge 213a and the third recess edge 2133 is a first distance L1, and the distance between the third recess edge 2133 and the first region 2100 is a second distance L2. L2 also represents the dimension of the portion of the first conductive material layer 211 between the first opening 2110 and the first recess 2130 in the second direction D2. The first distance L1 is greater than the second distance L2 (L1>L2). A larger first distance L1 increases the area of ​​the first recess 2130, allowing the first recess 2130 to provide a larger buffer space for the first conductive plate 30 during mechanical abuse. Furthermore, it is understood that the portion of the first conductive material layer 211 between the first opening 2110 and the first recess 2130 is covered by the first layer 50, making it difficult for the material in this portion of the first conductive material layer 211 to function effectively during charging and discharging. Furthermore, sufficient space must be reserved in the first region 2100 in the second direction D2 for connection to the first conductive plate 30. Therefore, under the condition that the first electrode sheet 21 has a constant dimension along the second direction D2, when the second distance L2 is small (the amount of active material covered by the first layer 50 and difficult to play a capacity role is reduced), the distance between the sixth side 2104 and the second end side 214 can be increased (i.e., the amount of active material between the sixth side 2104 and the second end side 214 that is not covered by the first layer 50 and can play a capacity role is increased), thereby reducing the impact on the capacity of the electrochemical device 100. In other embodiments, the first distance L1 can also be smaller than the second distance L2. In this case, due to the larger second distance L2, the first conductive material layer 211 located between the first opening 2110 and the first recess 2130 can effectively play a cushioning role.

[0155] It is understandable that Figure 8 As shown, when the first recess 2130 is viewed from the first direction D1, it is generally V-shaped. In this case, the first distance L1 is the distance from the first connecting side 213a to the intersection of the first recess side 2131 and the second recess side 2132 in the second direction D2. The second distance L2 is the distance from the intersection of the first recess side 2131 and the second recess side 2132 to the first region 2100 in the second direction D2.

[0156] When the first distance L1 is greater than the second distance L2, in some embodiments, the first distance L1 ranges from 1 mm to 6 mm (1 mm ≤ L1 ≤ 6 mm), the second distance L2 ranges from 0.3 mm to 4 mm (0.3 mm ≤ L2 ≤ 4 mm), and 0.1 ≤ L2 / L1 < 1. By setting the range of the first distance L1, the first recess 2130 can provide a larger buffer space for the first conductive plate 30 during mechanical abuse. This reduces the impact on the capacity of the electrochemical device 100 compared to a larger first distance L1 (i.e., the area of ​​the first recess 2130 increases, and the area of ​​the first conductive material layer 211 removed from the first recess 2130 also increases). By setting the range of the second distance L2, the first conductive material layer 211 between the first opening 2110 and the first recess 2130 can effectively act as a cushion. This reduces the impact on the capacity of the electrochemical device 100 compared to a larger second distance L2. In some embodiments, the ratio of the second distance L2 to the first distance L1 ranges from 0.1 to 1. That is, 0.1 ≤ L2 / L1 < 1. By setting a lower limit for the ratio of the second distance L2 to the first distance L1, the possibility of the first distance L1 accounting for a large proportion (the area of ​​the first recess 2130 is large) or the size of the portion of the first conductive material layer 211 between the first opening 2110 and the first recess 2130 in the second direction D2 being small is reduced. Therefore, the present application can reduce the impact on the capacity of the electrochemical device 100 and also enable this portion of the first conductive material layer 211 to effectively play a cushioning role.

[0157] like Figure 3 and Figure 5 As shown, in some embodiments, when viewed from the first direction D1, the first conductive plate 30 covers the middle portion of the first recess 2130 in the third direction D3. Therefore, in the third direction D3, the distance from the first conductive plate 30 to the first recess edge 2131 is a third distance L3, and the distance from the first conductive plate 30 to the second recess edge 2132 is a fourth distance L4. The third distance L3 is substantially equal to the fourth distance L4. For example, the difference between the third distance L3 and the fourth distance L4 does not exceed ±1.5 mm. In some specific embodiments, the third distance L3 ranges from 1 mm to 8 mm, and the fourth distance L4 ranges from 1 mm to 8 mm. This ensures that the first recess 2130 provides sufficient buffer space for the first conductive plate 30 while also reducing the impact on the capacity of the electrochemical device 100 caused by excessively large third distances L3 and L4.

[0158] It is understandable that Figure 7BAs shown, if the extending direction of the first recess edge 2131 and the second recess edge 2132 is not strictly parallel to the second direction D2, the third distance L3 is the maximum distance between the first conductive plate 30 and the first recess edge 2131 in the second direction D2, and the fourth distance L4 is the maximum distance between the first conductive plate 30 and the second recess edge 2132 in the second direction D2. As shown, Figure 8 As shown, if the first recess 2130 is approximately V-shaped when viewed from the first direction D1, at this time, the third distance L3 is the maximum distance between the first conductive plate 30 and the first recess edge 2131 in the second direction D2. The fourth distance L4 is the maximum distance between the first conductive plate 30 and the second recess edge 2132 in the second direction D2.

[0159] As shown, Figure 13 In other embodiments, as shown, the first conductive plate 30 can also deviate from the middle position of the first recess 2130 in the third direction D3 when viewed from the first direction D1, so that the third distance L3 is not equal to the fourth distance L4. In some specific embodiments, the third distance L3 can be smaller than the fourth distance L4.

[0160] As shown, Figure 3 and Figure 5 In some embodiments, as shown, the first conductive plate 30 covers the middle position of the first region 2100 in the third direction D3 when viewed from the first direction D1. Therefore, in the third direction D3, the distance between the first edge 2101 and the first conductive plate 30 is a fifth distance L5, and the distance between the second edge 2102 and the first conductive plate 30 is a sixth distance L6, and the fifth distance L5 is approximately equal to the sixth distance L6. For example, the difference between the fifth distance L5 and the sixth distance L6 is not more than ±1.5 mm. The fifth distance L5 and the sixth distance L6 are actually the size of the first region 2100 exposed to the first connecting area 31 of the first conductive plate 30 in the third direction D3. In some specific embodiments, the fifth distance L5 ranges from 1 mm to 10 mm, and the sixth distance L6 ranges from 1 mm to 10 mm. In this way, the heat generated at the first connecting area 31 when the electrochemical device 100 is charging can be dissipated through the first region 2100 exposed to the first connecting area 31, reducing the possibility of local overheating of the first conductive plate 30, while also reducing the impact on the capacity of the electrochemical device 100 when the fifth distance L5 or the sixth distance L6 is too large.

[0161] As shown, Figure 13 In other embodiments, as shown, when the first conductive plate 30 deviates from the middle position of the first region 2100 in the third direction D3 when viewed from the first direction D1, the fifth distance L5 can also be smaller or larger than the sixth distance L6. This is conducive to reducing the process requirements for connecting the first conductive plate 30 on the first region 2100.

[0162] As Figure 3 and Figure 5 As shown, in some embodiments, when the first concave portion 2130 only covers a portion of the first region 2100 in the second direction D2, the fourth distance L4 is smaller than the sixth distance L6. Figure 6 As shown, in other embodiments, when the first concave portion 2130 and the first area 2100 completely overlap in the second direction D2, the fourth distance L4 may be substantially equal to the sixth distance L6. For example, the difference between the fourth distance L4 and the sixth distance L6 does not exceed ±1.5 mm.

[0163] Among them, the first distance L1 to the sixth distance L6 can be measured respectively by direct measurement method, and the test steps include: disassembling the electrochemical device 100 and taking the first electrode 21 as a test sample; using a caliper or other suitable measuring tool to directly measure the values ​​of the first distance L1 to the sixth distance L6, or collecting an image of the first electrode 21 and measuring in the image.

[0164] like Figures 3 to 5 As shown, in some embodiments, when viewed from the first direction D1, the first region 2100 and the second region 2100' may be staggered in the third direction D3. In some specific embodiments, when viewed from the first direction D1, the first side 2101 and the third side 2105 are staggered in the third direction D3, and the second side 2102 and the fourth side 2106 are staggered in the third direction D3. The staggered first side 2101 and the third side 2105 provide the first electrode sheet 21 with a thickness transition at locations corresponding to the first side 2101 and the third side 2105. Similarly, the staggered second side 2102 and the fourth side 2106 provide the first electrode sheet 21 with a thickness transition at locations corresponding to the second side 2102 and the fourth side 2106. This thickness transition helps reduce the possibility of damage such as wrinkling caused by a sudden increase in pressure on the first current collector 210 during electrode sheet rolling, thereby reducing the possibility of poor appearance or internal interface defects in the electrochemical device 100. Furthermore, the thickness transition can also reduce the possibility of the first current collector 210 being torn when subjected to external collision or compression, thereby extending the service life of the electrochemical device 100.

[0165] Furthermore, in some embodiments, when viewed from the first direction D1, the second region 2100' completely covers the first region 2100. That is, when viewed from the first direction D1, the area of ​​the second region 2100' is larger than the area of ​​the first region 2100, so that in the first direction D1, the projection of the first region 2100 is completely within the projection of the second region 2100'. Figure 10A The recess 210c shown or Figure 10BThe protrusion 210d) shown may completely fall within the second region 2100', reducing the possibility of the conductive material falling off and causing a short circuit when the weld mark falls on the second conductive material layer 212, thereby extending the service life of the electrochemical device 100.

[0166] See also Figure 14 In other embodiments, when viewed from the first direction D1, the first region 2100 and the second region 2100' may completely overlap. Specifically, when viewed from the first direction D1, the first side 2101 overlaps with the third side 2105, the second side 2102 overlaps with the fourth side 2106, the fifth side 2103 overlaps with the seventh side 2107, and the sixth side 2104 overlaps with the eighth side 2108. In this case, when viewed from the first direction D1, the area of ​​the first region 2100 is equal to the area of ​​the second region 2100'.

[0167] See also Figure 15 and Figure 16 Another embodiment of the present application also provides an electrochemical device (not shown). This device differs from the aforementioned electrochemical device 100 in that, in the first electrode piece 21, the second region 2100' is separated from the first recess 2130 in the second direction D2, such that a portion of the second conductive material layer 212 exists between the second opening 2120 and the first recess 2130. Therefore, when viewed from the first direction D1, the first electrode piece 21 located between the first opening 2110 and the first recess 2130 is a double-sided coating region.

[0168] like Figure 16 As shown, the thickness T2 of the second position P2 includes the sum of the thicknesses of the first conductive plate 30, the first conductive material layer 211, the first current collector 210, and the second conductive material layer 212. At this time, at the second position P2, the portion of the second conductive material layer 212 between the second opening 2120 and the first recess 2130 can also play a role of raising the height in the first direction D1. When an external force acts on the back side of the electrochemical device 100 (i.e., Figure 2A When the shell 10 is shown facing the second wall 112 of the second area 2100', this portion of the second conductive material layer 212 can also bear part of the external force, reducing the possibility of the weld mark (such as the depression 210c or the protrusion 210d) piercing the isolation membrane 23 and contacting the second electrode 22 for short circuit, thereby extending the service life of the electrochemical device.

[0169] Among them, the electrochemical device of the present application (such as electrochemical device 100) includes all devices capable of generating electrochemical reactions. Specifically, the electrochemical device includes all types of primary batteries, secondary batteries, fuel cells, solar cells and capacitors (such as supercapacitors). Alternatively, the electrochemical device can be a lithium secondary battery, including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery and a lithium ion polymer secondary battery.

[0170] See also Figure 17 , one embodiment of the present application further provides an electronic device 1, which includes an electrochemical device (such as electrochemical device 100). The electronic device 1 is powered by the above-mentioned electrochemical device 100, and the electrochemical device 100 has a long service life. Among them, the electrochemical device 100 of the present application is applicable to electronic devices 1 in various fields. In one embodiment, the electronic device 1 of the present application can be, but is not limited to, a laptop computer, a pen-input computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large household battery and a lithium-ion capacitor, etc.

[0171] The present application is described in detail below through specific examples and comparative examples, wherein the electrochemical device is a battery, the first electrode is a positive electrode, and the first conductive plate is a positive conductive plate as an example, and the present application is described in conjunction with specific testing methods.

[0172] Examples 1-9

[0173] See Figure 3 On the first pole piece 21 after the cold pressing process, a laser cleaning method is used to clean the first opening 2110 in the first conductive material layer 211, so that the first area 2100 is exposed in the first opening 2110. A first recess 2130 is opened on the first end edge 213 of the first pole piece 21. When viewed from the first direction D1, the first opening 2110 and the first recess 2130 are separated. Then, the first conductive plate 30 is welded to the first area 2100. The second pole piece 22, the isolation membrane 23 and the electrolyte can adopt conventional designs. The first pole piece 21, the isolation membrane 23 and the second pole piece 22 are stacked and wound, placed in a shell, injected with electrolyte and packaged to make a battery, and the first pole piece 21 is the cathode pole piece.

[0174] The differences between Examples 1-9 lie in the value of the first distance L1, the value of the second distance L2, or the ratio of the second distance L2 to the first distance L1.

[0175] Comparative Example

[0176] The difference from embodiment 1-9 is that the first recess 2130 is not provided on the first pole piece 21 .

[0177] Dent test (also known as Dent test) was performed on 20 batteries of each of the examples and the comparative examples. The specific steps of the Dent test included: 1) charging the batteries to 100% SOC (State of Charge) at an ambient temperature of 25±5°C; 2) using a triangular rod extruder (model: DKBF-3KH, manufacturer: Dae Kyung), extruding a 6mm-diameter half-round head nail on the positive surface of the battery at the position corresponding to the first conductive plate 30, and then gradually increasing the pressure to 1300N at a speed of 300N / min; 3) observing whether the battery failed. The calculation formula of the Dent pass rate was: Dent pass rate = number of batteries passing the Dent test / number of batteries tested. The results are recorded in Table 1.

[0178] Table 1

[0179] first recess <![CDATA[L1 / mm]]> <![CDATA[L2 / mm]]> <![CDATA[L2 / L1]]> Dent pass rate Example 1 have 6 0.3 0.05 14 / 20 Example 2 have 5 0.5 0.1 20 / 20 Example 3 have 4 1.2 0.3 20 / 20 Example 4 have 1 0.5 0.5 20 / 20 Example 5 have 4 3 0.75 20 / 20 Example 6 have 4 4 1 20 / 20 Example 7 have 3 3 1 20 / 20 Example 8 have 2 2 1 20 / 20 Example 9 have 1.5 1.8 1.2 17 / 20 Comparative Example none none none none 6 / 20

[0180] Note: Dent pass rate X / 20 means that among the 20 samples tested, the number of samples passing the Dent test is X.

[0181] From the data in Table 1, compared with the comparative examples, the first recess 2130 is provided on the first tab 21 of the examples 1-9. The part of the first conductive material layer 211 between the first opening 2110 and the first recess 2130 can act as a cushion in the first direction D1, and this part of the first conductive material layer 211 can bear part of the external force during the Dent test. At the same time, the diameter of the half-round head nail is large (larger than the width of the first conductive plate 30 in the third direction D3), so the position of the first tab 21 with double-coated film on both sides of the first area 2100 can also bear part of the external force during the Dent test. Therefore, the possibility of the weld mark piercing the separator 23 and contacting the second tab 22 is reduced, and the pass rate of the batteries of the examples 1-9 during the Dent test is high. Furthermore, in the examples 1-9, the smaller proportion of the second distance L2 in the example 1 makes L2 / L1 smaller, so the size of the part of the first conductive material layer 211 between the first opening 2110 and the first recess 2130 in the second direction D2 is smaller, and the size of the part of the first conductive material layer 211 that can effectively act as a cushion is reduced, so the pass rate of the battery during the Dent test is reduced; the smaller proportion of the first distance L1 in the example 9 makes L2 / L1 larger, so the area of the first recess 2130 that can provide a buffer space for the first conductive plate 30 is reduced, so the pass rate of the battery during the Dent test is reduced.

[0182] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. An electrochemical device comprising an electrode assembly and a first conductive plate, wherein the electrode assembly comprises a first electrode plate, the first electrode plate comprises a first current collector and a first conductive material layer, the first current collector comprises a first surface, the first conductive material layer is disposed on the first surface, wherein: The first conductive material layer is provided with a first opening, the first surface includes a first area, the first area is configured as an area of ​​the first surface exposed by the first opening, and the first conductive plate is connected to the first area; When viewed from the first direction, the first pole piece includes a first end edge and a second end edge arranged opposite to each other in the second direction, and the first pole piece is provided with a first recess at the first end edge; when viewed from the first direction, the first recess is separated from the first region, and when viewed from the second direction, the first recess overlaps with the first region; A portion of the first conductive material layer is located between the first opening and the first recess. When viewed from the first direction, the first conductive plate covers a portion of the first area, the first conductive plate covers a portion of the first conductive material layer, and the first conductive plate covers a portion of the first recess. The first direction is perpendicular to the first area, and the second direction is perpendicular to the first direction.

2. The electrochemical device according to claim 1, wherein When viewed from the first direction, the first recess includes a first recess edge and a second recess edge arranged opposite to each other in a third direction, and a third recess edge connecting the first recess edge and the second recess edge. The first recess edge, the second recess edge and the third recess edge surround the first recess, and the third direction is perpendicular to both the first direction and the second direction.

3. The electrochemical device according to claim 2, wherein Observed from the first direction, the first end edge includes a first connecting edge connecting the first recessed edge, and the third recessed edge and the first connecting edge both extend along the third direction. In the second direction, the distance from the first connecting edge to the third recessed edge is a first distance L1, and the distance from the third recessed edge to the first area is a second distance L2, and the first distance L1 is greater than the second distance L2.

4. The electrochemical device according to claim 3, wherein 1 mm≤L1≤6 mm, 0.3 mm≤L2≤4 mm.

5. The electrochemical device according to claim 4, wherein 0.1≤L2 / L1<1.

6. The electrochemical device according to claim 2, wherein When viewed from the first direction, the first recess further includes a fourth recess edge and a fifth recess edge, the fourth recess edge connects the first recess edge and the third recess edge, the fifth recess edge connects the second recess edge and the third recess edge, the fourth recess edge is curved, and the fifth recess edge is curved.

7. The electrochemical device according to claim 1, wherein In the first direction, the thickness of the first conductive plate is smaller than the thickness of the first conductive material layer.

8. The electrochemical device according to claim 2, wherein Observed from the first direction, in the third direction, the distance from the first conductive plate to the edge of the first recess is a third distance L3, and the distance from the first conductive plate to the edge of the second recess is a fourth distance L4, and the third distance L3 is not equal to the fourth distance L4.

9. The electrochemical device according to claim 2, wherein The first electrode sheet further includes a second conductive material layer, the first current collector further includes a second surface disposed opposite to the first surface, the second conductive material layer being disposed on the second surface; the second conductive material layer is provided with a second opening, the second surface includes a second region, and the second region is configured as a region of the second surface exposed by the second opening; The first region and the second region overlap in the first direction, and the second region overlaps with the first recess when viewed from the second direction.

10. The electrochemical device according to claim 9, wherein The second region is disposed apart from the first recess in the second direction.

11. The electrochemical device according to claim 10, wherein When viewed from the first direction, the first area includes a first side and a second side arranged opposite to each other in the third direction, the first side and the first recess side are located on the first side of the first conductive plate, and the second side and the second recess side are located on the second side of the first conductive plate opposite to the first side; when viewed from the first direction, the second area includes a third side and a fourth side arranged opposite to each other in the third direction, the first side and the third side are located on the first side of the first conductive plate, and the second side and the fourth side are located on the second side of the first conductive plate; when viewed from the first direction, the first side and the third side are staggered, and / or the second side and the fourth side are staggered.

12. The electrochemical device according to claim 11, wherein When viewed from the first direction, the second area completely covers the first area.

13. The electrochemical device according to claim 9, wherein The second region is in contact with the first recess.

14. The electrochemical device according to claim 1, wherein The electrochemical device further includes a first layer comprising a first insulating material, wherein the first layer is bonded to the first region, and the first conductive plate is disposed between the first region and the first layer.

15. The electrochemical device according to claim 14, wherein When viewed from the first direction, the first layer completely covers the first opening and the first recess, and the first layer extends beyond the first end edge in the second direction.

16. The electrochemical device according to claim 1, wherein The first conductive plate is welded to the first region.

17. The electrochemical device according to claim 1, wherein The electrode assembly is a wound structure, and the first electrode sheet is a positive electrode sheet.

18. An electronic device comprising the electrochemical device according to any one of claims 1 to 17.

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