Electrochemical devices, modules, and electronic devices

Abstract

An electrochemical device includes an electrode assembly. The electrode assembly is formed by winding a stack. The stack includes a first electrode sheet, a second electrode sheet, and a separator. The first electrode sheet includes a first conductive layer, a first conductive material layer, and a first layer. The first conductive layer includes a first surface and a second surface oppositely arranged in a third direction, and the first surface includes a first region and a second region arranged in a first direction in sequence. The first conductive material layer is disposed on the first region. The second region is exposed from the first conductive material layer. The first conductive material layer includes a first conductive material region and a first edge region arranged in a second direction in sequence. The first edge region includes a first edge coinciding with a boundary line between the first region and the second region as viewed in the third direction, and the first edge is arranged obliquely relative to the second direction. Part of the first layer is disposed on the first region. The first layer extends from the first region to the second region as viewed in the third direction. The present application also provides a module and an electronic device.

Description

Technical Field

[0001] This application relates to the field of energy storage devices, and in particular to an electrochemical device, module and electronic device. Background Technology

[0002] Electrochemical devices (such as batteries) are widely used in electronic mobile devices, power tools, and electric vehicles. Electrochemical devices typically consist of electrodes and separators. However, during the rolling process, the conductive layer that collects current is prone to wrinkling. Damage such as wrinkles on the electrodes can lead to poor appearance and internal interface defects in the electrochemical device. Summary of the Invention

[0003] To address the above shortcomings, it is necessary to provide an electrochemical device that can reduce the likelihood of electrode wrinkling.

[0004] In addition, it is necessary to provide a module and an electronic device having the above-mentioned electrochemical device.

[0005] This application provides an electrochemical device including an electrode assembly. The electrode assembly is formed by winding a stack. The stack includes a first electrode, a second electrode, and a separator disposed between the first and second electrodes. The first electrode includes a first conductive layer, a first conductive material layer, and a first layer. The first conductive layer includes a first surface and a second surface disposed opposite each other in a third direction. The first surface includes a first region and a second region arranged sequentially in a first direction. The first conductive material layer is disposed in the first region. The second region is exposed outside the first conductive material layer. The first conductive material layer includes a first conductive material region and a first edge region, which are arranged sequentially along a second direction. The first direction, the second direction, and the third direction are perpendicular to each other. Viewed along the third direction, the first edge region includes a first side coinciding with the boundary line between the first and second regions, and the first side is inclined relative to the second direction. The first layer contains inorganic insulating particles, and a portion of the first layer is disposed in the first region. In the second direction, the first edge region connects the first conductive material region and the first layer. Viewed along the third direction, the first layer extends from the first region to the second region.

[0006] This application provides a first layer on the first region. This first layer not only covers burrs and reduces the possibility of short circuits, but also reduces the possibility of wrinkles forming in the first region. Furthermore, by extending the first layer from the first region to the second region, this application also reduces the possibility of wrinkles forming in the second region.

[0007] In some possible implementations, the first conductive layer includes a first end edge and a second end edge disposed opposite each other in a first direction. A first region includes the first end edge, and a second region includes the second end edge. The first layer extends from the first end edge to the second end edge. Therefore, the first layer can reduce the possibility of wrinkling in the second region due to greater pressure.

[0008] In some possible implementations, the first conductive layer further includes a third and a fourth end edge disposed opposite each other in a second direction. The first layer is closer to the third end edge than the first edge region. The electrochemical device also includes a first tab integrally disposed with the first conductive layer, the first tab being connected to the third end edge. This can improve energy density and reduce the risk of short circuits in the first tab.

[0009] In some possible implementations, viewed from a third-party perspective, the first conductive material region includes a second side that coincides with the boundary line between the first and second regions. The first side intersects the first layer at a first intersection point, and the second side intersects the fourth end edge at a second intersection point. In a first direction, the distance between the first intersection point and the second end edge is less than the distance between the second intersection point and the second end edge. This further reduces the likelihood of the second region wrinkling due to greater pressure.

[0010] In some possible implementations, viewed along a third direction, the first conductive material region includes a second side that coincides with the boundary line between the first and second regions. The first side intersects the first layer at a first intersection point, and the second side intersects the fourth end edge at a second intersection point. In the first direction, the distance between the first intersection point and the second end edge is greater than the distance between the second intersection point and the second end edge. This can, to some extent, reduce the possibility of wrinkling in the second region due to greater pressure, and also reduce the required size of the first layer in the first direction. Moreover, the degree of mixing between the first edge region and the first layer in their overlapping area is reduced, thereby improving the electrical performance of the edge region of the first edge region.

[0011] In some possible implementations, the shape of the first side is one of an arc, a wave, a broken line, or a diagonal line.

[0012] In some possible implementations, the first electrode further includes a second conductive material layer and a second layer. The second surface includes a third region and a fourth region arranged sequentially in a first direction. The second conductive material layer is disposed in the third region, and the fourth region is exposed above the second conductive material layer. The second conductive material layer includes a second conductive material region and a second edge region, which are arranged sequentially along a second direction. Viewed from a third direction, the second edge region includes a third side that coincides with the boundary line between the third and fourth regions, and the third side is inclined relative to the second direction. The second layer contains inorganic insulating particles. A portion of the second layer is disposed in the third region. In the second direction, the second edge region connects the second conductive material region and the second layer. Viewed from a third direction, the second layer extends from the third region to the fourth region. This application provides a second layer on the third region, which not only covers burrs and reduces the possibility of short circuits, but also reduces the possibility of wrinkles occurring in the third region. Furthermore, this application provides a second layer extending from the region coinciding with the third region away from the third side to the fourth region, reducing the possibility of wrinkles occurring in the fourth region.

[0013] In some possible implementations, viewed along a third direction, the second conductive material region includes a fourth side that coincides with the boundary line between the third and fourth regions. The third side intersects the second layer at a third intersection point, and the fourth side intersects the fourth end edge at a fourth intersection point. In a first direction, the distance between the third intersection point and the second end edge is less than the distance between the fourth intersection point and the second end edge. This reduces the likelihood of the fourth region being subjected to greater pressure and wrinkling.

[0014] In some possible implementations, in the first direction, the distance from the first end edge to the second edge is not equal to the distance from the first end edge to the fourth edge. For example, the distance from the first end edge to the second edge is greater than the distance from the first end edge to the fourth edge. This allows for the improvement of the overall conductive layer wrinkling problem through the design of the conductive material on one side of the first conductive layer, reducing the waste of conductive material and increasing energy density.

[0015] In some possible implementations, the outer surface of the electrode assembly is a second surface. Since the first conductive layer has high hardness, setting the outer surface of the electrode assembly as a second surface can increase the hardness of the electrode assembly, thereby increasing its resistance to mechanical shock.

[0016] In some possible implementations, viewed along a third direction, a first layer is also disposed on the first tab. The area of ​​the first layer disposed on the first tab is used to reduce the possibility that burrs at the edge of the first tab will puncture the separator and short-circuit upon contact with the second electrode.

[0017] In some possible implementations, in the second direction, the width of the first layer disposed on the first tab is 0.5 mm to 2 mm, which improves safety while reducing the impact on energy density.

[0018] In some possible implementations, there are multiple first tabs. This reduces the internal resistance of the first electrode, thereby increasing its charge / discharge rate, and prevents the current distribution from becoming too concentrated, promoting uniform current distribution, reducing polarization, and improving lithium plating.

[0019] In some possible implementations, multiple first electrodes are connected to the third end of the first region.

[0020] In some possible implementations, in the third direction, the thickness of the first layer is less than the thickness of the first edge region, and the thickness of the first edge region is less than the thickness of the first conductive material region. Therefore, the first edge region acts as a thickness buffer between the first conductive material region and the first layer, further reducing the possibility of wrinkles in the first conductive layer.

[0021] In some possible implementations, in the second direction, the width of the first layer is smaller than the width of the first edge region, and the width of the first edge region is smaller than the width of the first conductive material region. Because the width of the first conductive material region is larger, the area proportion of the first edge region in the first conductive material layer is reduced, which is beneficial for improving the energy density of the electrochemical device.

[0022] In some possible implementations, the width of the first layer is 0.5 mm to 3 mm in the second direction. This allows the first layer to fully cover the burrs at the third end while minimizing the impact of the first layer on the energy density of the electrochemical device.

[0023] In some possible implementations, the electrochemical device further includes a third layer comprising an insulating material. Viewed from a third direction, the third layer covers the first and second sides, and at least partially overlaps with either the first conductive material layer, the first layer, or the second region. Therefore, the third layer provides insulation protection for the exposed second region, reducing the likelihood of a short circuit between the second region and the second electrode during mechanical abuse, and also reducing the possibility of the second region tearing during mechanical abuse, and the torn first conductive layer piercing the separator and short-circuiting with the second electrode. In some possible implementations, the third layer is an adhesive layer. In some possible implementations, the third layer is adhesive tape.

[0024] In some possible implementations, in the second direction, the third layer extends beyond the third end edge from the region overlapping with the first layer. Therefore, the portion of the third layer extending beyond the third end edge can cover the burrs at the third end edge, reducing the possibility that the burrs will puncture the separator and short-circuit with the second electrode.

[0025] In some possible implementations, in the second direction, the third layer extends beyond the fourth end edge from the region overlapping with the first conductive material layer and the second region. Therefore, the portion of the third layer extending beyond the fourth end edge can cover the burrs at the fourth end edge, reducing the likelihood of these burrs piercing the separator and short-circuiting with the second electrode.

[0026] In some possible implementations, in the second direction, the distance of the third layer extending beyond the third end edge is 0.5mm to 2mm, and the distance of the third layer extending beyond the fourth end edge is 0.5mm to 2mm. This is beneficial for improving energy density.

[0027] In some possible implementations, the first layer also includes an adhesive used to bond the inorganic insulating particles together. The adhesive is selected from at least one of polyacrylamide, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyamide-imide, styrene-butadiene rubber, polyvinyl alcohol, polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl butyral, waterborne acrylic resin, carboxymethyl cellulose, or sodium carboxymethyl cellulose.

[0028] In some possible implementations, the inorganic insulating particles are selected from at least one of alumina, silicon dioxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium dioxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate.

[0029] In some possible implementations, the first electrode is a cathode, and the first conductive layer is an aluminum foil. This helps reduce the risk of wrinkles in the aluminum foil and short-circuit heating caused by contact between the aluminum foil and other polarities.

[0030] A second aspect of this application provides a module including a housing. The module also includes a plurality of electrochemical devices as described above, the plurality of electrochemical devices being disposed within the housing.

[0031] A third aspect of this application also provides an electronic device that includes the electrochemical device described above, or includes the module described above. Attached Figure Description

[0032] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0033] Figure 1 A front view of an electrochemical device provided according to an embodiment of this application.

[0034] Figure 2 for Figure 1 The diagram shown is a schematic of the electrochemical device before it is packaged.

[0035] Figure 3A for Figure 1 A top view of the electrode assembly of the electrochemical device shown.

[0036] Figure 3B for Figure 1 The electrochemical device shown is a cross-sectional view along IIIB-IIIB.

[0037] Figure 3C for Figure 1 The electrochemical device shown is a cross-sectional view along IIIC-IIIC.

[0038] Figure 4A for Figure 3A The first electrode of the electrode assembly shown is displayed in a frontal view in some embodiments after being unfolded.

[0039] Figure 4B for Figure 3A The first electrode of the electrode assembly shown is unfolded as a front view in some other embodiments.

[0040] Figure 5 for Figure 3A A schematic diagram of the back side of the first electrode of the electrode assembly after it has been unfolded.

[0041] Figure 6 for Figure 4A The diagram shown is a schematic of the first electrode after the third layer has been removed.

[0042] Figure 7 for Figure 5 The diagram shown is a schematic of the first electrode after the fourth layer has been removed.

[0043] Figure 8 for Figure 6 The first electrode shown is a cross-sectional view along VIII-VIII.

[0044] Figure 9A for Figure 3A The first electrode of the electrode assembly shown is unfolded as a partial enlarged view in some other embodiments.

[0045] Figure 9B for Figure 3A The first electrode of the electrode assembly shown is unfolded as a partial enlarged view in some other embodiments.

[0046] Figure 9C for Figure 3A The first electrode of the electrode assembly shown is unfolded as a partial enlarged view in some other embodiments.

[0047] Figure 9D for Figure 3A The first electrode of the electrode assembly shown is unfolded as a partial enlarged view in some other embodiments.

[0048] Figure 10 This is a front view of the first electrode sheet after it has been unfolded, according to another embodiment of this application.

[0049] Figure 11 for Figure 10 The diagram shown is a schematic of the first electrode after the third layer has been removed.

[0050] Figure 12 for Figure 10 The first pole piece shown is a cross-sectional view along XII-XII.

[0051] Figure 13This is a schematic diagram of the module provided in one embodiment of this application.

[0052] Figure 14 for Figure 13 The exploded view of the module shown.

[0053] Figure 15 This is a schematic diagram of the structure of an electronic device provided in one embodiment of this application.

[0054] Explanation of main component symbols

[0055] Electronic device 1

[0056] Stack 2

[0057] Casing 10

[0058] First shell 11

[0059] Second shell 12

[0060] Electrode assembly 20

[0061] First Extreme Film 21

[0062] Second pole piece 22

[0063] Separator 23

[0064] First pole ear 24

[0065] Second pole ear 25

[0066] First conductive plate 30

[0067] Second conductive plate 40

[0068] Third floor 50

[0069] Thirteenth end edge 51

[0070] Fourteenth end edge 52

[0071] Fourth floor 60

[0072] Electrochemical device 100

[0073] First shell region 111

[0074] Second shell region 112

[0075] Third shell region 121

[0076] Fourth shell region 122

[0077] First paragraph 201

[0078] First outer surface 201a

[0079] First bend section 202

[0080] Second paragraph, 203

[0081] Second outer surface 203a

[0082] Second bend section 204

[0083] First connection end 205

[0084] Second connection end 206

[0085] Third connection terminal 207

[0086] Fourth connection terminal 208

[0087] First conductive layer 210

[0088] First surface 210A

[0089] Zone 1, 210A1

[0090] Second District 210A2

[0091] Second surface 210B

[0092] Section 3, 210B1

[0093] Zone 4, 210B2

[0094] First end edge 210a

[0095] Second end edge 210b

[0096] Third end edge 210c

[0097] Fourth end edge 210d

[0098] First conductive material layer 211

[0099] Second conductive material layer 212

[0100] First floor 213

[0101] Fifth end edge 213a

[0102] Sixth end edge 213b

[0103] Seventh end edge 213c

[0104] Eighth end edge 213d

[0105] Second floor 214

[0106] Ninth end edge 214a

[0107] 10th end edge 214b

[0108] Eleventh end edge 214c

[0109] Twelfth end edge 214d

[0110] Second conductive layer 220

[0111] Third conductive material layer 221

[0112] Fourth conductive material layer 222

[0113] Module 300

[0114] Casing 301

[0115] First conductive material region 2111

[0116] First Edge Zone 2112

[0117] Dividing lines 2113 and 2123

[0118] First Division 2112A

[0119] Second partition 2112B

[0120] Second conductive material region 2121

[0121] Second Edge Zone 2122

[0122] First side S1

[0123] Second side S2

[0124] Third side S3

[0125] Fourth side S4

[0126] Intersection point P

[0127] First intersection point P1

[0128] Second intersection point P2

[0129] Third intersection point P3

[0130] Fourth intersection point P4

[0131] Dashed lines AA, BB

[0132] Winding direction D

[0133] Winding center axis O

[0134] First direction X

[0135] Second direction Y

[0136] Third direction Z

[0137] Fourth direction X'

[0138] Fifth direction Z'

[0139] Thickness T0~T4

[0140] Width W0~W2

[0141] Distance from L1 to L8 Detailed Implementation

[0142] The technical solutions in the embodiments of this application are described clearly and in detail below. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit this application.

[0143] The embodiments of this application will be described in detail below. However, this application may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided to provide a thorough and detailed understanding of this application to those skilled in the art.

[0144] Additionally, for brevity and clarity, the dimensions or thicknesses of various components and layers may be enlarged in the accompanying drawings. Throughout the text, the same numerical values ​​refer to the same elements. As used herein, the terms "and / or" and "and / or" include any and all combinations of one or more of the associated enumerated items. Furthermore, it should be understood that when element A is referred to as "connecting" element B, element A may be directly connected to element B, or there may be an intermediate element C and element A and element B may be indirectly connected to each other.

[0145] Furthermore, when describing the implementation of this application, the word "may" refers to "one or more implementations of this application".

[0146] The technical terms used herein are for the purpose of describing particular embodiments and are not intended to limit this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. It should be further understood that the term "comprising," as used in this specification, means the presence of the described features, values, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, values, steps, operations, elements, components, and / or combinations thereof.

[0147] Spatial terms, such as "above," may be used herein for convenience in describing the relationship between one element or feature and another element (or feature) or feature (or feature) illustrated in the figures. It should be understood that, in addition to the directions depicted in the figures, spatial terms are intended to include different orientations of the device or apparatus during use or operation. For example, if the device in the figure is flipped, an element described as "above" or "on" other elements or features would be oriented "below" or "under" other elements or features. Therefore, the exemplary term "above" can include both above and below orientations. It should be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or portion from another element, component, region, layer, or portion. Therefore, a first element, component, region, layer, or portion discussed below may be referred to as a second element, component, region, layer, or portion without departing from the teachings of the exemplary embodiments.

[0148] In this application, the design relationships of greater than, less than, or not equal to parameter values ​​need to exclude reasonable errors of the measuring equipment.

[0149] Please see Figures 1 to 3A One embodiment of this application provides an electrochemical device 100, including a housing 10 and an electrode assembly 20 disposed within the housing 10. For example... Figure 3A As shown, the electrode assembly 20 is formed by winding a stack 2. The stack 2 includes a first electrode 21, a second electrode 22, and a separator 23 disposed between the first electrode 21 and the second electrode 22. The separator 23 is used to prevent direct contact between the first electrode 21 and the second electrode 22, thereby reducing the possibility of a short circuit between the first electrode 21 and the second electrode 22. The electrochemical device 100 also includes a first conductive plate 30 and a second conductive plate 40. The first conductive plate 30 is electrically connected to the first electrode 21, and the second conductive plate 40 is electrically connected to the second electrode 22. The first conductive plate 30 and the second conductive plate 40 extend from one end of the housing 10 to connect to an external device (not shown). Please refer to further details. Figure 3B and Figure 3CThe electrode assembly 20 also includes a first tab 24 and a second tab 25. One end of the first tab 24 is electrically connected to the first electrode 21, and the other end is electrically connected to the first conductive plate 30. One end of the second tab 25 is electrically connected to the second electrode 22, and the other end is electrically connected to the second conductive plate 40. A three-dimensional coordinate system is established based on mutually perpendicular second directions Y, fourth directions X', and fifth directions Z'. In this application, the fourth direction X' is the direction from the first conductive plate 30 to the second conductive plate 40; the second direction Y is the direction in which the first conductive plate 30 or the second conductive plate 40 protrudes from the stack body 2, and is also the direction of the winding central axis O of the electrode assembly 20; the fifth direction Z' is the direction perpendicular to a surface of the first conductive plate 30. The first electrode 21, the separator 23, and the second electrode 22 are stacked sequentially and then wound around the winding central axis O to form the electrode assembly 20. For example, the stack body 2 can be wound clockwise (winding direction D) around the winding central axis O to form the electrode assembly 20. In some embodiments, after winding, the outermost layer of the first electrode 21, the separator 23, and the second electrode 22 is the first electrode 21. The first electrode 21 can be a positive electrode, and the second electrode 22 can be a negative electrode. Since the electrode has high hardness, setting the outermost layer to the first electrode 21 can increase the hardness of the electrode assembly 20, thereby increasing the electrode assembly 20's resistance to mechanical impact. In other embodiments, the first electrode 21 can be a negative electrode, and the second electrode 22 can be a positive electrode. In still other embodiments, after winding, the outermost layer of the first electrode 21, the separator 23, and the second electrode 22 can also be either the second electrode 22 or the separator 23.

[0150] like Figure 3A As shown, in the winding direction D, the electrode assembly 20 includes a first segment 201, a first bent segment 202, a second segment 203, and a second bent segment 204 connected in sequence. The fifth direction Z' is also the stacking direction of the first conductive layer 21 in the first segment 201 or the second segment 203. In some embodiments, the first segment 201 and the second segment 203 can be straight segments. In other embodiments, the electrode assembly 20 may also include four bent segments connected in sequence in the winding direction D.

[0151] The first segment 201 has a first outer surface 201a, and the second segment 203 has a second outer surface 203a. The connection point between the outermost first segment 201 and the outermost first bent segment 202 of the electrode assembly 20 is a first connection end 205. The first connection end 205 is... Figure 3AThe starting portion of the rightmost bend edge of the first bend segment 202 in the winding direction D, and the first connecting end 205 is also the portion where the dashed line BB formed by the rightmost bend edge located at the innermost part of the electrode assembly 20 and extending in the fifth direction Z' intersects with the first outer surface 201a. The connection point between the first bend segment 202 located at the outermost edge of the electrode assembly 20 and the second segment 203 located at the outermost edge of the electrode assembly 20 is the second connecting end 206. The second connecting end 206 is... Figure 3A The rightmost bend of the first bend segment 202 in the winding direction D is the final part. The second connecting end 206 is also the part where the dashed line BB formed by the rightmost bend of the innermost part of the electrode assembly 20 extending in the fifth direction Z' intersects with the second outer surface 203a. The connection point between the outermost second segment 203 of the electrode assembly 20 and the outermost second bend segment 204 of the electrode assembly 20 is the third connecting end 207. The third connecting end 207 is... Figure 3A The leftmost curve of the second bending segment 204 begins in the winding direction D. The third connecting end 207 is also the part where the dashed line AA formed by the bending edge located at the innermost part of the electrode assembly 20 and on the left side extends in the fifth direction Z' and intersects with the second outer surface 203a. The connection point between the outermost second bending segment 204 of the electrode assembly 20 and the outermost first segment 201 of the electrode assembly 20 is the fourth connecting end 208. The fourth connecting end 208 is... Figure 3A The leftmost curve of the second bend 204 ends in the winding direction D. The fourth connecting end 208 is also the part where the dashed line AA formed by the bend edge located at the innermost part of the electrode assembly 20 and on the left intersects with the first outer surface 201a in the fifth direction Z'. In the fifth direction Z', the first connecting end 205 and the second connecting end 206 are aligned, and the third connecting end 207 and the fourth connecting end 208 are aligned.

[0152] In some embodiments, the housing 10 can be a packaging bag encapsulated with an encapsulation film, i.e., the electrochemical device 100 is a pouch battery. For example... Figure 2 , Figure 3B and Figure 3C As shown, the housing 10 includes a first housing 11 and a second housing 12 disposed opposite to each other in the fifth direction Z'. The first housing 11 includes a first housing region 111 and a second housing region 112 that are interconnected. The three sides of the second housing region 112 are surrounded by the first housing region 111. The second housing 12 includes a third housing region 121 and a fourth housing region 122 that are interconnected. The three sides of the fourth housing region 122 are surrounded by the third housing region 121.

[0153] The second housing region 112 and the fourth housing region 122 together form an accommodating space (not shown) for housing the electrode assembly 20. The first housing region 111 is connected to the third housing region 121, thereby sealing the accommodating space. The first conductive plate 30 is electrically connected to the stack 2 via the first tab 24 and extends out of the housing 10 from the connection between the first housing region 111 and the third housing region 121, thus the first conductive plate 30 can be used to connect the stack 2 to an external device. The second conductive plate 40 is connected to the stack 2 via the second tab 25 and extends out of the housing 10 from the connection between the first housing region 111 and the third housing region 121, thus the second conductive plate 40 can be used to connect the stack 2 to an external device. In some embodiments, the first conductive plate 30 and the second conductive plate 40 may extend out of the housing 10 along a second direction Y. In other embodiments, the housing 10 may also be a metal housing, such as a steel housing or an aluminum housing.

[0154] like Figure 3A As shown, the first electrode 21 includes a first conductive material layer 211, a first conductive layer 210, and a second conductive material layer 212 stacked sequentially. The first conductive layer 210 may have a current-collecting function; for example, the first conductive layer 210 may contain aluminum or nickel. In some embodiments, the first conductive layer 210 contains aluminum. In some embodiments, the first electrode 21 is a cathode, and the first conductive layer 210 contains aluminum foil, which has relatively weak strength but good conductivity. Both the first conductive material layer 211 and the second conductive material layer 212 contain an active material, such as at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxide phosphate, lithium-rich manganese-based materials, or lithium nickel cobalt aluminum oxide.

[0155] The first conductive layer 210 includes a first surface 210A and a second surface 210B disposed opposite to each other. For example... Figure 3A As shown, when viewed along the second direction Y, the first surface 210A of the first conductive layer 210 is closer to the winding center axis O of the electrode assembly 20 than the second surface 210B. Figure 4A and Figure 5 As shown, after the first conductive layer 210 is unfolded, another three-dimensional coordinate system is established based on the mutually perpendicular first direction X, second direction Y, and third direction Z. In this application, the first direction X is the extension direction of the first electrode 21 before the stack body 2 is wound, and the third direction Z is also the stacking direction of the first conductive material layer 211, the first conductive layer 210, and the second conductive material layer 212 after the first conductive layer 210 is unfolded. Figure 4A and Figure 5As shown, viewed along the third direction Z, the first conductive layer 210 includes a first end edge 210a and a second end edge 210b disposed opposite each other in the first direction X. The first end edge 210a serves as the starting end for winding the first conductive layer 210, and the second end edge 210b serves as the ending end for winding the first conductive layer 210. Both the first end edge 210a and the second end edge 210b extend along the second direction Y. The first direction X is also the direction from the first end edge 210a to the second end edge 210b. Please refer to [further details omitted]. Figure 3A In some embodiments, after the stack 2 is wound around the central axis O to form the electrode assembly 20, the first end edge 210a is located at the center of the electrode assembly 20, and the second end edge 210b is located on the second outer surface 203a of the electrode assembly 20. For example... Figure 4A and Figure 5 As shown, the first conductive layer 210 also includes a third end edge 210c and a fourth end edge 210d disposed opposite each other in the second direction Y. The third end edge 210c is connected between the first end edge 210a and the second end edge 210b, and the fourth end edge 210d is also connected between the first end edge 210a and the second end edge 210b. The first tab 24 is connected to the third end edge 210c.

[0156] In some embodiments, the first tab 24 is integrally formed with the first conductive layer 210 and extends beyond the third end edge 210c. For example, the first tab 24 is cut from the first conductive layer 210. In some embodiments, there are multiple first tabs 24. By providing multiple first tabs 24, the current distribution of the first electrode 21 is not too concentrated, reducing the internal resistance of the first electrode 21 and thus improving the charge / discharge rate of the first electrode 21. Figure 3B As shown, multiple first tabs 24 can be connected to the first conductive plate 30 through the first adapter 240.

[0157] like Figure 4A and Figure 6As shown, in the first direction X, the first surface 210A includes a first region 210A1 and a second region 210A2 arranged sequentially. The first region 210A1 includes a first end edge 210a, and the second region 210A2 includes a second end edge 210b. A first conductive material layer 211 is disposed in the first region 210A1 and extends from the fourth end edge 210d to the third end edge 210c. The first conductive material layer 211 is substantially connected to the fourth end edge 210d and not connected to the third end edge 210c. The substantially connected nature allows for a distance of less than or equal to 2 mm between the edge of the first conductive material layer 211 near the fourth end edge 210d and the fourth end edge 210d. Viewed along the third direction Z, the first conductive material layer 211 is separated from the third end edge 210c. The second region 210A2 is also separated from the first conductive material layer 211, that is, the second region 210A2 is exposed above the first conductive material layer 211. Viewed from a third-party perspective (Z), the first region 210A1 and the second region 210A2 are interconnected in the first direction X, with the edge of the first conductive material layer 211 disposed on the first surface 210A and the second region 210A2, and its extension line, serving as the boundary. For example... Figure 4A and Figure 6 As shown by the dashed line in the enlarged view, the edge of the first conductive material layer 211 extends to the edge of the first surface 210A in the second direction Y, thereby dividing the first surface 210A in the first direction X into a first region 210A1 and a second region 210A2 arranged sequentially.

[0158] like Figure 5 and Figure 7 As shown, in the first direction X, the second surface 210B includes a third region 210B1 and a fourth region 210B2 arranged sequentially. A second conductive material layer 212 is disposed in the third region 210B1 and extends from the fourth end edge 210d to the third end edge 210c. The second conductive material layer 212 is substantially connected to the fourth end edge 210d but not to the third end edge 210c. This substantial connection allows for a distance of less than or equal to 2 mm between the edge of the second conductive material layer 212 near the fourth end edge 210d and the fourth end edge 210d. Viewed along the third direction Z, the second conductive material layer 212 is separated from the third end edge 210c. The fourth region 210B2 is separated from the second conductive material layer 212, i.e., the fourth region 210B2 is exposed outside the second conductive material layer 212. Viewed from a third-party perspective (Z), the third region 210B1 and the fourth region 210B2 are interconnected in the first direction (X), with the edge where the second conductive material layer 212 disposed on the second surface 210B meets the fourth region 210B2 and its extension line serving as the boundary. For example... Figure 5 and 7As shown by the dashed line in the enlarged view, the edge of the second conductive material layer 212 extends to the edge of the second surface 210B in the second direction Y, thereby dividing the second surface 210B in the first direction X into a third region 210B1 and a fourth region 210B2 arranged in sequence.

[0159] Please refer to the following: Figure 3A In some embodiments, after the stack 2 is wound around the central axis O to form the electrode assembly 20, the second surface 210B forms the outer surface of the electrode assembly 20. More specifically, the fourth region 210B2 forms the outer surface of the electrode assembly 20, that is, the electrode assembly 20 is finished with the first conductive layer 210.

[0160] like Figure 4A As shown, in some embodiments, when there are multiple first tabs 24, the multiple first tabs 24 can be connected to the third end edge 210c of the first region 210A1.

[0161] like Figure 4A and Figure 8 As shown, in the second direction Y, the first conductive material layer 211 includes a first conductive material region 2111 and a first edge region 2112 arranged sequentially. In the fabrication of the electrochemical device, an active material slurry is applied to the conductive layer by a coating method to form the conductive material layer, thereby preparing the electrode. Utilizing the fluidity of the coated active material slurry, the thickness of the conductive material layer on the conductive layer can be set such that the edge region is thinner than the main body region. The first conductive material region 2111 corresponds to the main body region, and the first edge region 2112 corresponds to the edge region. A boundary line 2113 exists between the first conductive material region 2111 and the first edge region 2112. The dividing line 2113 can be determined by the following methods: (1) Measure the thickness of the first conductive material layer 211 using a laser rangefinder or a micrometer. Take the average value of the thicknesses of 5 points as T1. Divide the first conductive material layer 211 into two regions of equal width in the second direction Y. The measurement point is located in the region closer to the fourth end edge 210d. (2) In the second direction Y, measure the thickness of the first conductive material layer 211 every 1 mm from the position away from the first conductive material region 2111 on the first edge region 2112 to the position closer to the first conductive material region 2111. Calculate the average thickness T' of three consecutive points. When T' ≥ 0.97T1, the last measurement point is the dividing point. (3) The extension line of the dividing point along the first direction X is the dividing line 2113.

[0162] In the third direction Z, the thickness T2 of the first edge region 2112 is less than the thickness T1 of the first conductive material region 2111. That is, the first conductive material layer 211 includes a first conductive material region 2111 with a thickness of T1, and also includes another part with a thickness T2 less than T1, the part corresponding to the thickness T2 being the first edge region 2112. In some embodiments, the thickness T1 of the first conductive material region 2111 is 20 μm to 200 μm. It can be understood that if the first electrode 21 is obtained by slicing along the slitting line, the thickness of the first conductive material region 2111 is basically uniform. However, when there is a certain distance between the edge of the first conductive material layer 211 near the fourth end edge 210d and the fourth end edge 210d, another edge region may also be provided on the side of the first conductive material region 2111 away from the first edge region 2112.

[0163] like Figure 5 and Figure 8 As shown, in the second direction Y, the second conductive material layer 212 includes a second conductive material region 2121 and a second edge region 2122 arranged sequentially. The distinction between the second conductive material region 2121 and the second edge region 2122 can be referred to the distinction between the first conductive material region 2111 and the first edge region 2112, and will not be repeated here. A boundary line 2123 exists between the second conductive material region 2121 and the second edge region 2122. The determination of the boundary line 2123 can be referred to the determination of the boundary line 2113. In the third direction Z, the thickness T4 of the second edge region 2122 can be less than the thickness T3 of the second conductive material region 2121. That is, the second conductive material layer 212 includes a second conductive material region 2121 with a thickness of T3, and also includes another portion with a thickness T4 less than T3; the portion corresponding to thickness T4 is the second edge region 2122. In some embodiments, the thickness T3 of the second conductive material region 2121 is 20 μm to 200 μm. It is understandable that the thickness of the first edge region 2112 may gradually decrease along the direction from the first conductive material region 2111 to the first edge region 2112. Therefore, the maximum thickness of the first edge region 2112 can be equal to the thickness T1 of the first conductive material region 2111, and the minimum thickness of the first edge region 2112 is zero. Similarly, the maximum thickness of the second edge region 2122 can be equal to the thickness T3 of the second edge region 2122, and the minimum thickness of the second edge region 2122 is zero. Therefore, the thickness T1 of the first edge region 2112 and the thickness T3 of the second edge region 2122 can refer to the average thickness, respectively.

[0164] like Figure 4A and Figure 6As shown, viewed along the third direction Z, the first edge region 2112 includes a first side S1 that coincides with the boundary line between the first region 210A1 and the second region 210A2. The first side S1 is the final end of the first edge region 2112 when it is wound. Viewed along the third direction Z, the first conductive material region 2111 includes a second side S2 that coincides with the boundary line between the first region 210A1 and the second region 210A2. The second side S2 is the final end of the first conductive material region 2111 when it is wound. The second side S2 connects to the first side S1. In some embodiments, the intersection of the first side S1 and the second side S2 may be located on the boundary line 2113.

[0165] The second side S2 extends along the second direction Y. The first side S1 is inclined relative to the second direction Y. This inclined setting means that the first side S1 is not set along the second direction Y, but deviates from it. For example... Figure 4A and Figure 6 As shown, in some embodiments, the first side S1 is inclined relative to the second end edge 210b in the second direction Y. In this case, viewed along the third direction Z, the first edge region 2112 includes a first partition 2112A and a second partition 2112B arranged sequentially in the first direction X. The boundary line between the first partition 2112A and the second partition 2112B is flush with the second side S2 in the second direction Y. Thus, during cold pressing, when the cold pressing roller passes over the second region 210A2, some pressure can be distributed on a portion of the first conductive material layer 211 (i.e., the second partition 2112B), including the first side S1, thereby reducing the possibility of the second region 210A2 being subjected to excessive pressure and wrinkling. The boundary line 2113 intersects the ending point of the first conductive material layer 211 at intersection point P. The entire first side S1 is inclined relative to the second direction Y. That is, the first side S1 extends inclinedly from intersection point P to the first intersection point P1. In other embodiments, only a portion of the first side S1 is inclined relative to the second direction Y. For example, a portion of the first side S1 near the first intersection point P1 is inclined relative to the second direction Y. In this case, the first side S1 begins to be inclined from a point between the intersection point P and the first intersection point P1. In other embodiments, a portion of the second side S2 near the first side S1 may also be inclined relative to the second direction Y. In this case, the first side S1 begins to be inclined from a point between the intersection point P and the second intersection point P2. Figure 4B As shown, in some other embodiments, the first side S1 may also be inclined relative to the second direction Y toward the first end side 210a. This can, to some extent, reduce the possibility of wrinkles forming in the second region 210A2 due to excessive pressure. Figure 4A The structure shown is more effective in reducing wrinkles in the first conductive layer 210.

[0166] like Figure 4A and Figure 6As shown, the first side S1 is arc-shaped, and the first side S1 protrudes in a direction away from the second region 210A2. Figure 9A As shown, in some embodiments, the first side S1 is arc-shaped and protrudes in the direction toward the second region 210A2. This reduces the likelihood of wrinkles forming in the second region 210A2 and also helps to increase the energy density of the electrochemical device 100. Figure 9B , Figure 9C and Figure 9D As shown, in some other embodiments, the shape of the first side S1 can also be one of a diagonal line, a wavy line, or a broken line.

[0167] like Figure 4A and Figure 6 As shown, the first electrode 21 further includes a first layer 213, and the first layer 213 may contain inorganic insulating particles. The first layer 213 is disposed in the region of the first region 210A1 that is closer to the third end edge 210c than the fourth end edge 210d. Therefore, when viewed along the third direction Z, the first layer 213 partially overlaps with the first region 210A1. In the second direction Y, the first edge region 2112 connects the first conductive material region 2111 and the first layer 213, that is, the first edge region 2112 is closer to the first layer 213 than the first conductive material region 2111. In some embodiments, when viewed along the third direction Z, the first layer 213 partially overlaps with the first edge region 2112 (e.g., ...). Figure 8 (As shown). The first side S1 intersects the first layer 213 at the first intersection point P1, and the second side S2 intersects the fourth end side 210d at the second intersection point P2. Therefore, when the first side S1 is inclined towards the second end side 210b relative to the second direction Y, in the first direction X, the distance L1 between the first intersection point P1 and the second end side 210b is less than the distance L2 between the second intersection point P2 and the second end side 210b. Figure 4B As shown, when the first side S1 is inclined towards the first end side 210a relative to the second direction Y, in the first direction X, the distance L1 between the first intersection point P1 and the second end side 210b is greater than the distance L2 between the second intersection point P2 and the second end side 210b.

[0168] In some embodiments, the inorganic insulating particles of the first layer 213 are selected from at least one of alumina, silicon dioxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium dioxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate. The inorganic insulating particles help reduce the risk of short circuits, and their certain hardness and thickness help mitigate the risk of wrinkles in the first conductive layer 210. Further, the first layer 213 may also include an adhesive. The inorganic insulating particles are disposed in the adhesive, and the adhesive is used to bond the inorganic insulating particles into a layered structure. The adhesive material is selected from at least one of polyacrylamide, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyamide-imide, styrene-butadiene rubber, polyvinyl alcohol, polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl butyral, waterborne acrylic resin, carboxymethyl cellulose, or sodium carboxymethyl cellulose.

[0169] like Figure 4A and Figure 6As shown, the first layer 213 includes a fifth end edge 213a and a sixth end edge 213b disposed opposite to each other in the first direction X, and a seventh end edge 213c and an eighth end edge 213d disposed opposite to each other in the second direction Y. In some embodiments, when viewed along the third direction Z, the seventh end edge 213c coincides with the third end edge 210c. The first layer 213 can reduce the possibility that burrs on the first conductive layer 210 at the third end edge 210c (the burrs may be formed during the cutting process of the first conductive layer 210, which is not limited in this application) will puncture the separator 23 and short-circuit with the second electrode 22, or reduce the possibility that the first electrode 21 and the second electrode 22 will short-circuit due to the shrinkage of the edge of the separator 23 at high temperature. In addition, it can be understood that a portion of the first region 210A1 may be reserved to be exposed to the conductive material layer, so that this portion of the region can be cut after the electrode is cold-pressed to obtain the first electrode tab 24. At this time, the first layer 213 can also reduce the thickness difference between the first electrode 21 in the first region 210A1 covered by the first conductive material layer 211 and the first region 210A1 exposed by the first conductive material layer 211, improve the problem of uneven pressure on the first region 210A1 during cold pressing, reduce the possibility of wrinkling in the first region 210A1, and facilitate the uniform distribution of current. In some embodiments, when the first layer 213 partially overlaps with the first edge region 2112, the projection of the eighth end edge 213d in the third direction Z is located within the projection of the first edge region 2112 in the third direction Z. In this way, the first layer 213 can fully cover the area of ​​the first region 210A1 that is closer to the third end edge 210c than the fourth end edge 210d. In some specific embodiments, the width W0 of the first layer 213 in the third direction Z is 0.5mm to 3mm. Optionally, the width W0 of the first layer 213 is 1.6mm to 2.6mm. In other embodiments, when viewed along the third direction Z, the first layer 213 may also be adjacent to the first edge region 2112. It can be understood that "adjacent" means that the areas of the first layer 213 and the first edge region 2112 that are in contact with each other do not overlap, that is, when viewed along the third direction Z, there is no overlapping part between the first layer 213 and the first edge region 2112.

[0170] Viewed along the third direction Z, the first layer 213 can also cover part of the first edge S1. Furthermore, viewed along the third direction Z, the first layer 213 can also extend from the area overlapping with the first region 210A1 away from the first edge S1 to the second region 210A2. Thus, the first layer 213 can further reduce the possibility that burrs on the first conductive layer 210 at the third end edge 210c will puncture the separator 23 and short-circuit with the second electrode 22, or further reduce the possibility that the first electrode 21 and the second electrode 22 will short-circuit due to edge shrinkage of the separator 23 at high temperatures. Moreover, when the cold-pressing roller presses over the second region 210A2 along the first direction X (or the opposite direction of the first direction X), some of the pressure can be distributed on the first layer 213, reducing the possibility that the second region 210A2 will be subjected to excessive pressure and wrinkle.

[0171] In summary, this application provides a first layer 213 on the first region 210A1. The first layer 213 not only covers burrs and reduces the possibility of short circuits, but also reduces the possibility of wrinkles forming in the first region 210A1. Furthermore, by extending the first layer 213 from the area overlapping with the first region 210A1 away from the first edge S1 to the second region 210A2, this application can further reduce the possibility of wrinkles forming in the second region 210A2 due to greater pressure.

[0172] like Figure 4B As shown, when the first side S1 is inclined towards the first end edge 210a relative to the second direction Y, the required size of the first layer 213 in the first direction X can be reduced while the first layer 213 covers a portion of the first side S1, i.e., the amount of inorganic insulating particles and adhesive used is reduced. Furthermore, the degree of mixing between the first edge region 2112 and the first layer 213 in their overlapping area is reduced, thereby improving the electrical performance of the edge region of the first edge region 2112. The inclination direction of the first side S1 can be adjusted by changing the coating order of the first conductive material layer 211 and the first layer 213, and the coating amount of the first layer 213. In some embodiments, if the coating amount of the first layer 213 is large, the portion of the first layer 213 mixed with the first edge region 2112 will cause the winding end of the first edge region 2112 to move along the first direction X, thereby forming the first side S1 inclined towards the second end edge 210b. Figure 4A The structure shown. Conversely, if the coating amount of the first layer 213 is less, the degree of mixing between the first edge region 2112 and the first layer 213 in the overlapping area is reduced, causing the formed first edge S1 to tilt towards the first end edge 210a, that is... Figure 4B The structure shown.

[0173] like Figure 4A and Figure 6As shown, in some embodiments, viewed along the third direction Z, the first layer 213 extends from the first end edge 210a to the second end edge 210b. That is, the seventh end edge 213c of the first layer 213 coincides with the first end edge 210a, and the eighth end edge 213d of the first layer 213 coincides with the second end edge 210b, so that the first layer 213 spans the entire second region 210A2 in the first direction X. Therefore, during the process of the cold press roller pressing through the entire second region 210A2, the first layer 213 can disperse part of the pressure on the second region 210A2, reducing the possibility of wrinkles occurring in the second region 210A2 due to excessive pressure.

[0174] like Figure 8 As shown, the thickness of the first edge region 2112 gradually decreases along the direction from the first conductive material region 2111 to the first edge region 2112, and the thickness of the first layer 213 also gradually decreases along the direction from the first conductive material region 2111 to the first edge region 2112. Viewed along the third direction Z, the first layer 213 partially overlaps with the first edge region 2112. Therefore, at least in the overlapping region of the first layer 213 and the first edge region 2112, the thickness of the first layer 213 is greater than the thickness of the first edge region 2112. In some embodiments, along the third direction Z, the thickness T2 of the first edge region 2112 (here referring to the average thickness of the first edge region 2112) is between the thickness T0 of the first layer 213 (here referring to the average thickness of the first layer 213) and the thickness T1 of the first conductive material region 2111. That is, the thickness T0 of the first layer 213 is less than the thickness T2 of the first edge region 2112, and the thickness T2 of the first edge region 2112 is less than the thickness T1 of the first conductive material region 2111. Therefore, the first edge region 2112 acts as a thickness buffer between the first conductive material region 2111 and the first layer 213, further improving the problem of uneven pressure during cold pressing and reducing the possibility of wrinkling in the first conductive layer 210. In some embodiments, 5μm≤T0≤50μm can improve the wrinkling problem of the first conductive layer 210, enhance safety, and reduce the impact on energy density. The average thickness of the first edge region 2112 can be measured as follows: along the electrode width direction (opposite to the second direction Y), the thickness of the first edge region 2112 (i.e., the distance from the surface of the first edge region 2112 to the first surface 210A) is measured every 1mm using a laser rangefinder or a micrometer, obtaining multiple thickness values. The thickness T2 of the first edge region 2112 is the average of the above multiple thickness values. The average thickness of the first layer 213 is measured in a similar way.

[0175] like Figure 4A and Figure 6As shown, in some embodiments, in the second direction Y, the width W1 of the first edge region 2112 is between the width W0 of the first layer 213 and the width W2 of the first conductive material region 2111. That is, the width W0 of the first layer 213 is smaller than the width W1 of the first edge region 2112, and the width W1 of the first edge region 2112 is smaller than the width W2 of the first conductive material region 2111. Since the width W2 of the first conductive material region 2111 is larger, the area ratio of the first edge region 2112 in the first conductive material layer 211 is reduced, which is beneficial to improving the energy density of the electrochemical device 100. In some specific embodiments, the width W0 of the first layer 213 is 0.5 mm to 3 mm. In this way, the first layer 213 can fully cover the burrs of the third end edge 210c, and the influence of the first layer 213 on the energy density of the electrochemical device 100 is reduced. Optionally, the width W0 of the first layer 213 is 1.6 mm to 2.6 mm.

[0176] like Figure 7 As shown, in some embodiments, viewed along the third direction Z, the second edge region 2122 includes a third side S3 that coincides with the boundary line between the third region 210B1 and the fourth region 210B2, and the third side S3 is the final section for winding the second edge region 2122. Viewed along the third direction Z, the second conductive material region 2121 includes a fourth side S4 that coincides with the boundary line between the third region 210B1 and the fourth region 210B2, and the fourth side S4 is the final section for winding the second conductive material region 2121. The third side S3 is connected to the fourth side S4. The boundary line 2123 passes through the intersection between the third side S3 and the fourth side S4. The fourth side S4 extends along the second direction. The third side S3 is inclined relative to the second direction Y. In some embodiments, the third side S3 is inclined relative to the second direction Y toward the first end edge 210a. In other embodiments, the third side S3 may also be inclined relative to the second direction Y toward the second end edge 210b.

[0177] like Figure 5 and Figure 7As shown, in some embodiments, the first electrode 21 may further include a second layer 214, and the second layer 214 may also contain inorganic insulating particles. The second layer 214 is disposed in the region of the third region 210B1 that is closer to the third end edge 210c than the fourth end edge 210d. Therefore, when viewed along the third direction Z, the second layer 214 and the third region 210B1 partially overlap. In the second direction Y, the second edge region 2122 connects the second conductive material region 2121 and the second layer 214. The third edge S3 intersects the second layer 214 at a third intersection point P3, and the fourth edge S4 intersects the fourth end edge 210d at a fourth intersection point P4. Therefore, when the third edge S3 is inclined towards the first end edge 210a relative to the second direction Y, in the first direction X, the distance L3 between the third intersection point P3 and the second end edge 210b is greater than the distance L4 between the fourth intersection point P4 and the second end edge 210b.

[0178] like Figure 5 and Figure 7 As shown, the second layer 214 includes a ninth end edge 214a and a tenth end edge 214b disposed opposite each other in the first direction X, and an eleventh end edge 214c and a twelfth end edge 214d disposed opposite each other in the second direction Y. In some embodiments, viewed along the third direction Z, the eleventh end edge 214c coincides with the third end edge 210c, and the second layer 214 is connected to the first conductive material region 2111. The second layer 214 can reduce the possibility that the burrs of the first conductive layer 210 at the third end edge 210c will pierce the separator 23 and short-circuit with the second electrode 22, or reduce the possibility that the first electrode 21 and the second electrode 22 will short-circuit due to the shrinkage of the edge of the separator 23 at high temperature. Viewed along the third direction Z, the second layer 214 also extends from the region coinciding with the third region 210B1 away from the third side S3 to the fourth region 210B2.

[0179] In some embodiments, the inorganic insulating particles of the second layer 214 are selected from at least one of alumina, silicon dioxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium dioxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate. The inorganic insulating particles of the second layer 214 may be the same as or different from those of the first layer 213. Further, the second layer 214 may also include an adhesive, in which the inorganic insulating particles are disposed. The adhesive is selected from at least one of polyacrylamide, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyimide, polyamide-imide, styrene-butadiene rubber, polyvinyl alcohol, polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl butyral, waterborne acrylic resin, carboxymethyl cellulose, or sodium carboxymethyl cellulose. The adhesive of the second layer 214 may be the same as or different from that of the first layer 213.

[0180] This application provides a second layer 214 on the third region 210B1. The second layer 214 not only covers burrs and reduces the possibility of short circuits, but also reduces the possibility of wrinkles forming in the third region 210B1. Furthermore, this application provides that the second layer 214 extends from the area overlapping with the third region 210B1 away from the third edge S3 to the fourth region 210B2, which can also reduce the possibility of wrinkles forming in the fourth region 210B2 due to greater pressure.

[0181] like Figure 6 and Figure 7 As shown, in some embodiments, the first conductive material layer 211 and the second conductive material layer 212 are coated with different lengths in the first direction X. In the first direction X, the distance L5 from the first end edge 210a to the second edge S2 is not equal to the distance L6 from the third end edge 210c to the fourth edge S4. For example, in some embodiments, in the first direction X, the distance L5 from the first end edge 210a to the second edge S2 is greater than the distance L6 from the first end edge 210a to the fourth edge S4. Since the position of the second edge S2 can roughly reflect the position of the winding end of the first conductive material layer 211, and the position of the fourth edge S4 can roughly reflect the position of the winding end of the second conductive material layer 212, therefore, as... Figure 3A As shown, after the stacked body 2 is wound around the central axis O to form the electrode assembly 20, the end of the first conductive material layer 211 is located on the outermost first electrode 21 of the multilayer first electrode 21 included in the first segment 201, and the end of the second conductive material layer 212 is located on the second outermost first electrode 21 of the multilayer first electrode 21 included in the first segment 201. Thus, compared to the case where the end of the second conductive material layer 212 also extends to the outermost first electrode 21 of the first segment 201, this application can reduce the waste of conductive material and increase energy density.

[0182] like Figure 3A and Figure 4AAs shown, in some embodiments, the electrochemical device 100 further includes a third layer 50. The third layer 50 comprises an insulating material, which may be selected from at least one of polypropylene, polyethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, or polyethylene glycol. The third layer 50 may be a single-sided or double-sided adhesive containing the insulating material. In other embodiments, the third layer 50 may also be a ceramic coating. Viewed along the third direction Z, the third layer 50 covers the first side S1 and the second side S2, and the third layer 50 partially overlaps with the first conductive material layer 211, the first layer 213, the first region 210A1, and the second region 210A2. Thus, the third layer 50 can provide insulation protection for the exposed second region 210A2, reducing the possibility of the second region 210A2 short-circuiting with the second electrode 22 during mechanical abuse, and also reducing the possibility of the second region 210A2 tearing during mechanical abuse, and the torn first conductive layer 210 piercing the separator 23 and short-circuiting with the second electrode 22. The third layer 50 includes a thirteenth end edge 51 and a fourteenth end edge 52 disposed opposite to each other in the first direction X. Viewed along the third direction Z, the fourteenth end edge 52 is closer to the second end edge 210b than the thirteenth end edge 51. In some embodiments, in the first direction X, the distance L7 between the fourteenth end edge 52 and the second end edge S2 is less than the distance L8 between the thirteenth end edge 51 and the second end edge S2, such that the area of ​​the third layer 50 covering the second region 210A2 is larger than the area of ​​the third layer 50 covering the first conductive material layer 211. This not only allows the third layer 50 to provide better protection for the exposed second region 210A2, but also reduces the impact of the third layer 50 covering the first conductive material layer 211, preventing some lithium ions from successfully detaching.

[0183] Understandable, compared to Figure 4A When the first side S1 is tilted towards the second end side 210b, Figure 4B When the first side S1 is tilted towards the first end side 210a relative to the second direction Y, the contact area between the third layer 50 and the second region 210A2 can be increased, thereby improving the stability of the third layer 50 attached to the second region 210A2.

[0184] Similarly, compared to Figure 9A When the first side S1 protrudes towards the direction of the second region 210A2, Figure 4A When the first side S1 protrudes away from the second region 210A2, the contact area between the third layer 50 and the second region 210A2 can be increased, thereby improving the stability of the third layer 50 attached to the second region 210A2. Figures 9B to 9D The shape of the first side S1 shown can also increase the contact area between the third layer 50 and the second area 210A2 to some extent.

[0185] In some embodiments, in the second direction Y, the third layer 50 extends from the region overlapping with the first layer 213 beyond the third end edge 210c. Thus, the portion of the third layer 50 extending beyond the third end edge 210c can cover the burrs at the third end edge 210c, reducing the possibility of the burrs piercing the separator 23 and short-circuiting with the second electrode 22. In the second direction Y, the third layer 50 may also extend from the region overlapping with the first conductive material layer 211 and the second region 210A2 beyond the fourth end edge 210d. Thus, the portion of the third layer 50 extending beyond the fourth end edge 210d can cover the burrs at the fourth end edge 210d, reducing the possibility of the burrs piercing the separator 23 and short-circuiting with the second electrode 22. In some specific embodiments, in the second direction Y, the distance by which the third layer 50 extends beyond the third end edge 210c is 0.5mm to 2mm, and the distance by which the third layer 50 extends beyond the fourth end edge 210d is 0.5mm to 2mm.

[0186] like Figure 3A and Figure 5 As shown, similarly, in order to provide insulation protection for the fourth zone 210B2 and reduce the possibility of contact short circuits in the fourth zone 210B2, a fourth layer 60 can also be provided on the fourth zone 210B2. The material of the fourth layer 60 and its position on the fourth zone 210B2 can be set with reference to the material of the third layer 50 and its position on the second zone 210A2, and will not be described in detail here.

[0187] like Figure 3A As shown, in some embodiments, the second electrode 22 includes a third conductive material layer 221, a second conductive layer 220, and a fourth conductive material layer 222 stacked together. The second conductive layer 220 may have a current-collecting function; for example, the second conductive layer 220 may contain copper, nickel, or carbon-based conductors. In some embodiments, the second conductive layer 220 contains copper. Both the third conductive material layer 221 and the fourth conductive material layer 222 contain an active material, which may be selected from at least one of graphite-based materials, alloy-based materials, lithium metal, and alloys thereof. Graphite-based materials may be selected from at least one of artificial graphite and natural graphite; alloy-based materials may be selected from at least one of silicon, silicon oxide, tin, and titanium sulfide. To reduce the possibility of wrinkling in the second electrode 22, the structure of the second electrode 22 may adopt a design similar to that of the first electrode 21, such as also providing a first layer on the second conductive layer 220 and extending the first layer to the blank area of ​​the second conductive layer 220 where no conductive material layer is provided.

[0188] Please see Figures 10 to 12Another embodiment of this application provides an electrochemical device (not shown), which differs from the electrochemical device 100 described above in the structure of the first electrode 21. In this embodiment, viewed along the third direction Z, the first layer 213 extends beyond the third end edge 210c from the region overlapping with the first region 210A1 along the second direction Y. Therefore, viewed along the third direction Z, the first layer 213 partially overlaps with the first tab 24, and the seventh end edge 213c of the first layer 213 is provided on the first tab 24. The overlapping region of the first layer 213 and the first tab 24 is used to reduce the possibility of burrs on the edge of the first tab 24 piercing the separator 23 and short-circuiting with the second electrode 22. The region of the first tab 24 without the first layer 213 is used to extend out of the housing 10 and electrically connect to an external device. It is understood that in this case, the width W0 of the first layer 213 does not include the width of the portion of the first layer 213 overlapping with the first tab 24.

[0189] In some embodiments, in the second direction Y, the width of the overlapping area between the first layer 213 and the first tab 24 is 0.5 mm to 2 mm, such that the first tab 24 has sufficient width to extend out of the housing 10 and be electrically connected to an external device in the second direction Y. In some specific embodiments, the width of the overlapping area between the first layer 213 and the first tab 24 is 0.5 mm to 1.5 mm.

[0190] The electrochemical device 100 of this application includes all devices capable of undergoing electrochemical reactions. Specifically, the electrochemical device 100 includes all types of primary cells, secondary cells, fuel cells, solar cells, and capacitors (e.g., supercapacitors). Optionally, the electrochemical device 100 can be a lithium secondary battery, including lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, and lithium-ion polymer secondary batteries.

[0191] Please see Figure 13 and Figure 14 One embodiment of this application also provides a module 300, including a housing 301 and a plurality of electrochemical devices 100. The plurality of electrochemical devices 100 are disposed within the housing 301 and are connected in parallel or in series with each other.

[0192] Please see Figure 15This application also provides an electronic device 1, including the electrochemical device 100 described above, in one embodiment. In another embodiment, the electronic device 1 may further include the module 300 described above. In one embodiment, the electronic device 1 of this application may be, but is not limited to, a laptop computer, a pen input computer, a mobile computer, an e-book player, a portable telephone, a portable fax machine, a portable copier, a portable printer, a stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini CD, a transceiver, an electronic notebook, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, an electric bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, a power tool, a flashlight, a camera, a large household battery, and a lithium-ion capacitor, etc.

[0193] The performance of the electrochemical device provided in this application is described below through specific embodiments and comparative examples. Specifically, the application is illustrated using the first electrode as the positive electrode of a lithium-ion battery and the first conductive layer as the positive current collector, along with specific preparation processes and testing methods. Those skilled in the art should understand that the preparation methods described in this application are merely examples, and any other suitable preparation methods are within the scope of this application.

[0194] Example 1

[0195] Preparation of the first electrode 21: Lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 97.5:1.0:1.5. N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75 wt%, and the mixture was stirred evenly. A 12 μm thick aluminum foil was used as the first conductive layer 210. Adhesive tape was pasted onto the first surface 210A of the first conductive layer 210, and then the slurry was uniformly coated onto the first region 210A1 of the first surface 210A with the adhesive tape. The coating was then dried at 110°C. The above coating steps were repeated on the second surface 210B of the first conductive layer 210.

[0196] An insulating slurry, comprising boehmite and polytetrafluoroethylene, is coated onto the first conductive layer 210. After drying to remove the solvent, a first layer 213 and a second layer 214 are obtained. The first layer 213 and the second layer 214 extend from the first end edge 210a to the second end edge 210b of the first conductive layer 210, respectively.

[0197] Then, the first electrode 21 is obtained through cold pressing, tab cutting, and slicing (i.e., cutting and slicing the electrode to the required size). The first conductive material layer 211 and the second conductive material layer 212 on the two opposite surfaces of the first electrode 21 have the same thickness, and the values ​​of each parameter are recorded in Table 1.

[0198] Example 2

[0199] The difference from Embodiment 1 is that the first layer 213 does not extend to the second region 210A2 of the first surface 210A, and the second layer does not extend to the fourth region 210B2 of the second surface 210B.

[0200] Example 3

[0201] The difference from Example 1 is the values ​​of parameters such as L2, L4, and T2.

[0202] Then, 10 first electrode sheets 21 were taken from each set of embodiments and comparative examples, and it was observed whether wrinkles or other problems occurred in the first electrode sheets 21 after cold pressing. The cold pressing yield of the first electrode sheets 21 in each embodiment and comparative example was calculated accordingly. The cold pressing yield refers to the percentage of first electrode sheets 21 in each set that exhibited wrinkles or other problems out of the total number of first electrode sheets 21 in that set. The corresponding test results are recorded in Table 1.

[0203] Table 1

[0204]

[0205]

[0206] As can be seen from the test results in Table 1, compared with Example 2, Example 1 has a relatively higher cold pressing efficiency because the first layer 213 and the second layer 214 are extended to the second region 210A2 and the fourth region 210B2, respectively. Compared with Example 3, Example 1 has a relatively higher cold pressing efficiency because the first side S1 of the conductive material is inclined.

[0207] The above-disclosed embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of this application. Therefore, any equivalent variations made in accordance with this application are still within the scope of this application.

Claims

1. An electrochemical device comprising an electrode assembly formed by winding a stack, the stack comprising a first electrode, a second electrode, and a separating membrane disposed between the first electrode and the second electrode, wherein, The first electrode includes a first conductive layer, a first conductive material layer, and a first layer. The first conductive layer includes a first surface and a second surface disposed opposite each other in a third direction. The first surface includes a first region and a second region arranged sequentially in a first direction. The first conductive material layer is disposed in the first region, and the second region is exposed in the first conductive material layer. The first conductive material layer includes a first conductive material region and a first edge region, and the first conductive material region and the first edge region are arranged sequentially along a second direction. The first direction, the second direction, and the third direction are perpendicular to each other; viewed from the third direction, the first edge region includes a first side that coincides with the boundary line between the first region and the second region, and the first side is inclined relative to the second direction; The first layer contains inorganic insulating particles, and a portion of the first layer is disposed in the first region. In the second direction, the first edge region connects the first conductive material region and the first layer. Viewed from the third direction, the first layer extends from the first region to the second region. The first conductive layer includes a first end edge and a second end edge disposed opposite to each other in the first direction, the first region includes the first end edge, the second region includes the second end edge, and the first conductive layer also includes a third end edge and a fourth end edge disposed opposite to each other in the second direction, wherein the first layer is closer to the third end edge than the first edge region. Viewed from the third direction, the first conductive material region includes a second side that coincides with the boundary line between the first region and the second region; the first side intersects the first layer at a first intersection point, and the second side intersects the fourth end side at a second intersection point. In the first direction, the distance between the first intersection point and the second end side is less than the distance between the second intersection point and the second end side.

2. The electrochemical device as claimed in claim 1, wherein, The first layer extends from the first end edge to the second end edge.

3. The electrochemical device as described in claim 1, wherein, The electrochemical device further includes a first tab integrally disposed with the first conductive layer, and the first tab is connected to the third end.

4. The electrochemical device according to any one of claims 1 to 3, wherein, The shape of the first side is one of arc, wavy, broken line or oblique line.

5. The electrochemical device as described in claim 3, wherein, The first electrode further includes a second conductive material layer and a second layer. The second surface includes a third region and a fourth region arranged sequentially in the first direction. The second conductive material layer is disposed in the third region, and the fourth region is exposed in the second conductive material layer. The second conductive material layer includes a second conductive material region and a second edge region, which are arranged sequentially along the second direction. Viewed from the third direction, the second edge region includes a third side that coincides with the boundary line between the third region and the fourth region, and the third side is inclined relative to the second direction; The second layer contains inorganic insulating particles, and a portion of the second layer is disposed in the third region. In the second direction, the second edge region connects the second conductive material region and the second layer. Viewed from the third direction, the second layer extends from the third region to the fourth region.

6. The electrochemical device as claimed in claim 5, wherein, Viewed from the third direction, the second conductive material region includes a fourth side that coincides with the boundary line between the third region and the fourth region; the third side intersects the second layer at a third intersection point, and the fourth side intersects the fourth end edge at a fourth intersection point. In the first direction, the distance between the third intersection point and the second end edge is less than the distance between the fourth intersection point and the second end edge.

7. The electrochemical device as claimed in claim 6, wherein, In the first direction, the distance from the first end edge to the second edge is not equal to the distance from the first end edge to the fourth edge.

8. The electrochemical device as claimed in claim 5, wherein, The outer surface of the electrode assembly is the second surface.

9. The electrochemical device as claimed in claim 3, wherein, The first layer is also disposed on the first electrode tab.

10. The electrochemical device as claimed in claim 9, wherein, In the second direction, the width of the first layer disposed on the first tab is 0.5 mm to 2 mm.

11. The electrochemical device as claimed in claim 3, wherein, There are multiple first electrodes, and multiple first electrodes are connected to the third end edge of the first region.

12. The electrochemical device as claimed in claim 1, wherein, In the third direction, the thickness of the first layer is less than the thickness of the first edge region.

13. The electrochemical device as claimed in claim 1, wherein, In the second direction, the width of the first layer is smaller than the width of the first edge region, and the width of the first edge region is smaller than the width of the first conductive material region.

14. The electrochemical device of claim 13, wherein, In the second direction, the width of the first layer is 0.5 mm to 3 mm.

15. The electrochemical device as claimed in claim 3, wherein, The electrochemical device further includes a third layer comprising an insulating material; viewed from the third direction, the third layer covers the first side and the second side, and the third layer at least partially overlaps with any one of the first conductive material layer, the first layer, and the second region.

16. The electrochemical device of claim 15, wherein, In the second direction, the third layer extends beyond at least one of the third end edge or the fourth end edge.

17. The electrochemical device of claim 16, wherein, In the second direction, the distance of the third layer extending beyond the third end edge is 0.5 mm to 2 mm, and the distance of the third layer extending beyond the fourth end edge is 0.5 mm to 2 mm.

18. The electrochemical device of claim 1, wherein, The first layer further includes an adhesive, the adhesive being selected from at least one of polyacrylol, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyamide-imide, styrene-butadiene rubber, polyvinyl alcohol, polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl butyral, waterborne acrylic resin, carboxymethyl cellulose, or sodium carboxymethyl cellulose.

19. The electrochemical device of claim 1, wherein, The inorganic insulating particles are selected from at least one of alumina, silicon dioxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium dioxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate.

20. The electrochemical device of claim 1, wherein, The first electrode is a cathode, and the first conductive layer is an aluminum foil.

21. A module comprising a housing, wherein, The module further includes a plurality of electrochemical devices as described in any one of claims 1 to 20, wherein the plurality of electrochemical devices are disposed within the housing.

22. An electronic device, wherein, The electronic device includes an electrochemical device as described in any one of claims 1 to 20, or includes a module as described in claim 21.

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