Electrochemical device and electronic device

Abstract

An electrochemical device and an electronic device. The electrochemical device includes a housing, an electrode assembly, a first conductive plate, a first layer, and a second layer. The housing includes a first wall and a side wall. The electrode assembly is in a jelly-roll structure and includes a first tab. The first conductive plate includes a first conductive region and a second conductive region connected to the first tab and the first wall, respectively. The second conductive region extends in a second direction and includes a first end connected to the first conductive region and a second end opposite to the first end. In a first direction, the first layer is disposed between the electrode assembly and the second conductive region. The first layer includes a first side extending along an edge of the electrode assembly and a second side connected to the first side, the second side overlapping the electrode assembly, and the second side being further away from the edge of the electrode assembly than the first side to form a gap, as viewed in the first direction. The second end overlaps the first layer, and a first region of the second layer overlaps the first layer, as viewed in the first direction. The present application can improve reliability and service life.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and more particularly to an electrochemical device and an electronic device having said electrochemical device. Background Technology

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

[0003] Electrochemical devices typically include a conductive plate that connects electrodes to a housing, thereby leading the polarity of the electrodes out through the housing. However, in extreme cases caused by improper use, burrs on the conductive plate may puncture the separator, causing a short circuit. In cases of mechanical abuse, the conductive plate may also experience fatigue fracture, leading to device failure and impacting its safety, reliability, and lifespan. Summary of the Invention

[0004] Therefore, it is necessary to provide an electrochemical device with high reliability and safety.

[0005] Furthermore, it is also necessary to provide an electronic device having the aforementioned electrochemical device.

[0006] This application provides an electrochemical device, including a housing and an electrode assembly. The housing includes a first wall and a sidewall connecting to the first wall. The first wall and the sidewall enclose a receiving cavity, in which the electrode assembly is housed. The direction from the first wall to the electrode assembly is a first direction. The electrode assembly has a wound structure and includes a first electrode, a second electrode, and a separating membrane disposed between the first electrode and the second electrode. The electrochemical device also includes a first conductive plate and a first layer. The first conductive plate includes a first conductive region and a second conductive region connected together, the second conductive region being bent relative to the first conductive region. The first conductive region is connected to the first electrode, and the second conductive region is connected to the first wall. The second conductive region includes a first end connected to the first conductive region and a second end disposed opposite to the first end. The second conductive region extends from the first end along a second direction perpendicular to the first direction. The first layer comprises an insulating material. In the first direction, the first layer is disposed between the electrode assembly and the second conductive region. Viewed from the first direction, the first layer includes a first side extending bent along the edge of the electrode assembly and a second side connected to the first side. The second side overlaps with the electrode assembly, and because the second side is further away from the edge of the electrode assembly than the first side, it creates a gap in the first layer. Viewed from the first direction, the second end overlaps with the first layer. The second layer contains insulating material. The second layer includes a first region covering a second conductive area, and the first region includes a first partition and a second partition connected together. Viewed from the first direction, the first partition covers the gap, and the second partition overlaps with the first layer.

[0007] In this application, the first layer is used to isolate the electrode assembly and the first wall, reducing the possibility of a short circuit caused by direct contact between the electrode assembly and the first wall. The first layer can also cover the burrs in the second conductive area, reducing the possibility of the burrs piercing the isolation membrane and causing a short circuit. Moreover, by setting the second side further away from the edge of the electrode assembly than the first side, when the electrochemical device is subjected to mechanical abuse, the compression of the first layer on the bend between the first and second conductive areas can be reduced, thereby reducing the possibility of the first conductive plate breaking under stress at the bend and causing the electrochemical device to fail, and also reducing the possibility of the sharp point generated after the first conductive plate breaks piercing the isolation membrane and causing a short circuit. Therefore, the reliability and service life of the electrochemical device are improved. Furthermore, by setting the first area of ​​the second layer to cover the gap, the first area can work with the first layer to isolate the electrode assembly and the first wall, reducing the possibility of a short circuit that may be caused by the gap in the first layer. In addition, the second layer can also reduce the possibility of warping at the second side and make the first layer less likely to move within the housing.

[0008] In some possible implementations, when viewed from the first direction, the first end is located within the notch. This can reduce the friction between the first end and the sidewall.

[0009] In some possible implementations, the surface of the first layer facing the first wall includes a first recess, at which the first layer contacts the second conductive region. Thus, while maintaining the thickness of the first layer, the total thickness of the second conductive region and the first layer in the first direction can be reduced, thereby improving energy density.

[0010] In some possible implementations, the second side includes a bend. Considering that a notch may be formed on the second side when the first layer is cut, by including a bend on the second side, the possibility of the notch further expanding and forming a crack during the installation of the first layer can be reduced.

[0011] In some possible implementations, a third direction is defined to be perpendicular to the first and second directions. The dimension of the second side in the third direction is d2, and the dimension of the second conductive region in the third direction is d, where d2 > d. Therefore, the first layer can fully cover the second conductive region, reducing the possibility of burrs in the second conductive region piercing the insulating film and causing a short circuit. Furthermore, the first layer can effectively isolate the electrode assembly from the first wall, reducing the possibility of a short circuit due to direct contact between the electrode assembly and the first wall.

[0012] In some possible implementations, the first electrode includes a first current collector and a first active material layer disposed on the surface of the first current collector. The first current collector includes a first portion separated from the first active material layer, and a first conductive region is connected to the first portion. This reduces the impact of the first conductive region on the energy density of the electrochemical device in the second direction, and also reduces the impact of the first conductive region on the overall flatness of the electrode assembly.

[0013] In some possible implementations, in the second direction, a first conductive region is disposed on the surface of the first portion facing the sidewall. Due to the obstruction of the first portion, the possibility of burrs in the first conductive region piercing the insulating membrane and causing a short circuit can be reduced.

[0014] In some possible implementations, a first region is disposed between the second conductive region and the electrode assembly in a first direction. The first region serves to cooperate with the first layer to jointly isolate the electrode assembly and the first wall, and to jointly cover the burrs of the second conductive region, thereby reducing the possibility of short circuits.

[0015] In some possible implementations, the second layer further includes a second region connecting to the first region. The second region covers the first conductive region. The second region is used to cover burrs in the first conductive region, further reducing the possibility of these burrs piercing the insulating film and causing a short circuit.

[0016] In some possible implementations, the electrochemical device further includes a third layer comprising an insulating material. The third layer includes a third region disposed in the first direction between the second conductive region and the first wall. The third region includes a third partition and a fourth partition connected together. Viewed from the first direction, the third partition covers the gap, and the fourth partition overlaps with the first layer. The third region, together with the first layer, serves to isolate the electrode assembly and the first wall, reducing the likelihood of a short circuit.

[0017] In some possible implementations, the third layer also includes a fourth region connecting the third region. In the second direction, a first conductive region is located between the second and fourth regions. The fourth region is used to cover burrs or solder marks on the first conductive region.

[0018] In some possible implementations, the second layer comprises a stacked adhesive layer and a substrate. The adhesive layer contains an insulating material. The substrate is bonded to the first conductive plate via the adhesive layer. Since the third layer does not bond the electrode assembly, the electrolyte located between the first layer and the first wall after electrolyte injection can fully wet the electrode assembly, improving the interface during cycling, reducing capacity decay caused by lithium plating, black spots, purple spots, etc., and improving the cycling performance of the electrochemical device.

[0019] In some possible implementations, the substrate material is selected from at least one of polyimide or polyethylene terephthalate. In some possible implementations, the insulating material of the adhesive layer is selected from at least one of butadiene, isoprene, styrene, methyl methacrylate, butyl methacrylate, isooctyl acrylate, or butyl acrylate, thereby giving the adhesive layer better adhesion.

[0020] In some possible implementations, the fourth partition includes a second end that faces away from the third partition in the second direction. The second end and the sidewall have a dimension of d5 in the second direction, and the radius of the first wall is R, where d5 < 0.4R. This reduces the influence of the third region on the connection (welding) area between the second conductive plate and the first wall, i.e., reduces the possibility of the third region interfering with the connection area and causing connection failure.

[0021] In some possible implementations, a third direction is defined to be perpendicular to the first and second directions. The dimension of the second side in the third direction is d2, and the dimension of the first region in the third direction is d3, where d2 < d3. This allows the first region, in conjunction with the first layer, to jointly isolate the electrode assembly and the first wall, reducing the likelihood of a short circuit.

[0022] In some possible implementations, the distance between the second side and the sidewall in the second direction is a first distance L. The second partition includes a first end that is away from the first partition in the second direction. The dimensions of the first end and the sidewall in the second direction are d1, where 0.4d1 < L < d1. This reduces the possibility that the electrolyte between the first layer and the first wall may not fully wet the electrode assembly after liquid injection when the value of L is too small. Therefore, the wetting effect of the electrode assembly is improved, thereby improving the interface during the cycle, reducing the capacity decay caused by lithium plating, black spots, purple spots, etc., and improving the cycle performance of the electrochemical device.

[0023] In some possible implementations, when viewed from the first direction, the second conductive region overlaps with the winding center axis of the electrode assembly. Therefore, the second conductive region has a larger size in the second direction, which is beneficial for improving the connection strength between the second conductive region and the first wall.

[0024] In some possible implementations, a cavity is provided at the starting end of the winding of the electrode assembly. Viewed from a first direction, a first layer covers the cavity. This application eliminates the need to provide openings in the first layer corresponding to the cavity in order to ensure sufficient electrolyte wetting of the electrode assembly, thereby reducing the short-livedness of solder joints in the first conductive area contacting the second electrode through the aforementioned openings and affecting the lifespan of the electrochemical device.

[0025] In some possible implementations, the housing further includes a second wall connected to the sidewall and disposed opposite to the first wall. The second wall has a conductive element that is electrically insulated from it. The electrode assembly also includes a second conductive plate electrically connected to the second electrode, and the second conductive plate is connected to the conductive element. Thus, the first wall and the conductive element exhibit opposite polarities, allowing the electrochemical device to supply power to external components.

[0026] In some possible implementations, the electrochemical device is a coin cell, and the edges of the electrode assembly are roughly circular when viewed from a first direction. Since coin cells are generally small in size, this implementation does not require reducing the compression of the first layer at the bend of the first conductive plate by reducing the size of the electrode assembly, which is beneficial for improving energy density.

[0027] A second aspect of this application also provides an electronic device including the aforementioned electrochemical device. The electronic device is powered by the electrochemical device, and by positioning the second side further away from the edge of the electrode assembly than the first side, the electrochemical device reduces the likelihood of breakage of the first conductive plate, thereby maintaining high reliability and service life. Attached Figure Description

[0028] 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:

[0029] Figure 1A This is a three-dimensional structural diagram of an electrochemical device according to an embodiment of this application.

[0030] Figure 1B for Figure 1A The electrochemical device shown is viewed from the first direction as a top view.

[0031] Figure 2A for Figure 1A The electrochemical device shown is a cross-sectional view along II-II.

[0032] Figure 2B for Figure 2A The diagram shows the structure of the first electrode plate of the electrochemical device as viewed from the fifth direction before winding.

[0033] Figure 2C for Figure 2B The diagram shows the structure of the first electrode when viewed from the first direction.

[0034] Figure 3 for Figure 1B The electrochemical device shown is a cross-sectional view along line III-III.

[0035] Figure 4 for Figure 3 An enlarged view of the electrochemical device shown at point A.

[0036] Figure 5 for Figure 1B The electrochemical device shown is a cross-sectional view along VV.

[0037] Figure 6 for Figure 1A The electrochemical device shown is viewed from below in the first direction after the first wall of the casing has been removed.

[0038] Figure 7 for Figure 6 The electrochemical device shown is viewed from below in the first direction after the third layer has been removed.

[0039] Figure 8 for Figure 7 A cross-sectional view of the second layer of the electrochemical device shown.

[0040] Figure 9 This is a schematic diagram of the structure of an electrochemical device according to another embodiment of this application.

[0041] Figure 10 This is a cross-sectional view of an electrochemical device according to another embodiment of this application.

[0042] Figure 11 This is a schematic diagram of the structure of an electronic device according to one embodiment of this application.

[0043] Explanation of main component symbols

[0044] Electronic device 1

[0045] Casing 10

[0046] First Wall 11

[0047] Second Wall 12

[0048] Side wall 13

[0049] Conductive component 14

[0050] First insulating layer 15

[0051] Second insulating layer 16

[0052] Electrode assembly 20

[0053] First paragraph 20a

[0054] Second paragraph 20b

[0055] First Extreme Film 21

[0056] Second pole piece 22

[0057] Separator 23

[0058] First conductive plate 30

[0059] First conductive region 31

[0060] Second conductive region 32

[0061] Second conductive plate 40

[0062] Third conductive region 41

[0063] Fourth conductive region 42

[0064] First floor 50

[0065] First side 51

[0066] Second side 52

[0067] Second floor 60

[0068] Area 1, 61

[0069] Second area 62

[0070] Third floor 70

[0071] Third District 71

[0072] Fourth District 72

[0073] Fourth floor 80

[0074] Electrochemical device 100

[0075] First opening 120

[0076] First Edge 131

[0077] Second edge 132

[0078] Conductive part 141

[0079] Installation section 142

[0080] Seal 143

[0081] First current collector 210

[0082] First active material layer 211

[0083] Second active material layer 212

[0084] Second current collector 220

[0085] Third active substance layer 221

[0086] Fourth active material layer 222

[0087] Page 301 (First Page)

[0088] Page 2, 302

[0089] First end 321

[0090] Second end 322

[0091] Third end 421

[0092] Fourth end 422

[0093] Fifth surface 501

[0094] Surface 502

[0095] first recess 503

[0096] First section 611

[0097] Second section 612

[0098] Adhesive layer 601

[0099] Substrate 602

[0100] Third Division 711

[0101] Fourth Division 712

[0102] Second opening 1410

[0103] Winding start end 2001

[0104] Part 1 2100

[0105] First surface 2101

[0106] Second surface 2102

[0107] Part Two 2200

[0108] Third surface 2201

[0109] Fourth surface 2202

[0110] First end 6120

[0111] Second end 7120

[0112] Receptacle S1

[0113] Cavity S2

[0114] Winding center axis O

[0115] Gap C

[0116] Dimensions d, d1, d2, d3, d4, d5

[0117] radius R

[0118] First distance L

[0119] First intersection point P1

[0120] Second intersection point P2

[0121] First direction X

[0122] Second direction Y

[0123] Third direction Z

[0124] Fourth direction Y'

[0125] Fifth direction Z'

[0126] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0127] 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.

[0128] 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.

[0129] 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.

[0130] Furthermore, when describing the implementation of this application, the word "may" refers to "one or more implementations of this application".

[0131] 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.

[0132] 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.

[0133] As used in this article, "parallel" and "perpendicular" are used to describe the ideal state between two components. In actual production or use, two components may exist in a state that is approximately parallel or perpendicular. For example, combined with numerical descriptions, parallel can refer to the angle between two straight lines within ±10°, parallel can also refer to the dihedral angle between two planes within ±10°, and parallel can also refer to the angle between a straight line and a plane within ±10°. Perpendicular can refer to the angle between two straight lines within 90±10°, perpendicular can also refer to the dihedral angle between two planes within 90±10°, and perpendicular can also refer to the angle between a straight line and a plane within 90±10°. The two components described as "parallel" or "perpendicular" do not have to be absolutely straight lines or planes; they can be approximately straight lines or planes. From a macroscopic perspective, if the overall direction of extension is a straight line or plane, the component can be considered a "straight line" or "plane".

[0134] 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.

[0135] Please see Figures 1A to 2A and Figure 3 This application provides an electrochemical device 100, including a housing 10, an electrode assembly 20, and an electrolyte (not shown). The housing 10 includes a first wall 11, a second wall 12, and a side wall 13. The first wall 11 and the second wall 12 are disposed opposite each other in a first direction X. Viewed from the first direction X, the first wall 11 may be generally circular, and the second wall 12 may also be generally circular. The first wall 11 and the second wall 12 may be arranged parallel to each other and are both perpendicular to the first direction X. A first edge 131 of the side wall 13 connects to the first wall 11, and a second edge 132 of the side wall 13 connects to the second wall 12, thereby forming a generally cylindrical receiving cavity S1 within the housing 10. Viewed from the first direction X, the first wall 11 covers the receiving cavity S1. The electrode assembly 20 and the electrolyte are housed within the receiving cavity S1, and the first direction X is also the direction from the first wall 11 to the electrode assembly 20. In some embodiments, the electrochemical device 100 is a coin cell. The side wall 13 and the second wall 12 can be integrally formed, and the second wall 12 and the side wall 13 can be welded or snap-fitted together. The shell 10 can be made entirely of steel. In some embodiments, the steel shell 10 includes the elements Fe and C, and may also include one or more of the elements Ni, Co, Al, Mn, Cr, Cu, Mg, Mo, S, Si, Ti, V, Pb, Sb, N, and P. For example, the first wall 11 is made of steel, and the second wall 12 is also made of steel.

[0136] In some embodiments, the second wall 12 may also be provided with a conductive element 14 that is electrically insulated from the second wall 12. For example, the second wall 12 is provided with a first opening 120 communicating with the receiving cavity S1, and the conductive element 14 can be installed in the first opening 120 by means of bonding or riveting. The conductive element 14 may include a conductive part 141 and a mounting part 142 connected to each other. The conductive part 141 is disposed in the first opening 120, and the mounting part 142 is disposed on the surface of the second wall 12 facing away from the first wall 11. Further, a first insulating layer 15 may be provided between the conductive element 14 and the second wall 12, and the first insulating layer 15 is used to electrically isolate the conductive element 14 and the second wall 12. The first insulating layer 15 can be fixed between the conductive element 14 and the second wall 12 by an interference fit. In other embodiments, the first insulating layer 15 can also be fixed between the conductive element 14 and the second wall 12 by means of riveting. The material of the first insulating layer 15 may be polyethylene, polypropylene, propylene-ethylene copolymer, polyetheretherketone, polyvinylidene fluoride, or polytetrafluoroethylene.

[0137] In some embodiments, the conductive portion 141 may be provided with a second opening 1410, which is located within the first opening 120 when viewed from the first direction X. Electrolyte can flow into the receiving cavity S1 through the second opening 1410. To reduce the risk of leakage after injection, a seal 143 may be installed on the conductive portion 141, and the seal 143 covers the second opening 1410.

[0138] like Figure 2A and Figure 3 As shown, the electrode assembly 20 has a wound structure and a winding central axis O. In some embodiments, the first direction X is also the direction of the winding central axis O of the electrode assembly 20. The electrode assembly 20 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 prevents 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. For simplicity, the separator 23 is shown as a dashed line (composed of a plurality of short, spaced lines). In some embodiments, when viewed from the first direction X, the edge of the electrode assembly 20 may also be generally circular. In some embodiments, after winding, the separator 23 is located at least part of the outermost layer of the electrode assembly 20. For example, the separator 23 is located at the outermost layer of the electrode assembly 20. The separator 23 can form a protective layer, reducing the risk of short circuits due to wear on the electrodes inside this portion of the separator 23, thereby increasing the electrode assembly 20's resistance to mechanical shock. In other embodiments, the first electrode 21 or the second electrode 22 may also be located on the outermost layer of the electrode assembly 20.

[0139] The electrode assembly 20 may have a cavity S2 at its winding start end 2001. The winding center axis O passes through the cavity S2 along the first direction X. During fabrication, the first electrode 21, the separator 23, and the second electrode 22 can be wound using a winding needle (not shown). After the electrode assembly 20 is formed, the winding needle is removed, thereby forming the cavity S2 within the electrode assembly 20. In some embodiments, such as Figure 2A and Figure 3 As shown, the innermost ring of the separator 23 is the winding start end 2001 of the electrode assembly 20.

[0140] like Figure 2B and Figure 2C As shown, after the first electrode 21 is unfolded, another three-dimensional coordinate system is established based on the mutually perpendicular first direction X, fourth direction Y', and fifth direction Z'. The fourth direction Y' is defined as the extension direction of the first electrode 21 before winding, and the fifth direction Z' is the thickness direction of the first electrode 21 after unfolding. Please refer to [the diagram / reference]. Figures 2A to 3The first electrode 21 includes a first active material layer 211, a first current collector 210, and a second active material layer 212 stacked sequentially. The fifth direction Z' is the stacking direction of the first current collector 210 and the first active material layer 211 after unfolding. The first current collector 210 includes a first surface 2101 and a second surface 2102 disposed opposite to each other. The first surface 2101 is further away from the winding center axis O than the second surface 2102. The first active material layer 211 is disposed on the first surface 2101, and the second active material layer 212 is disposed on the second surface 2102. The first current collector 210 may contain aluminum or nickel. In some embodiments, when the first electrode 21 is a negative electrode, the first current collector 210 contains copper. Both the first active material layer 211 and the second active material layer 212 contain an active material, which may be selected from at least one of graphite-based materials, alloy materials, lithium metal, and their alloys. Graphite-based materials may be selected from at least one of artificial graphite and natural graphite; alloy materials may be selected from at least one of silicon, silicon oxide, tin, and titanium sulfide.

[0141] The second electrode 22 includes a stacked third active material layer 221, a second current collector 220, and a fourth active material layer 222. The second current collector 220 includes a third surface 2201 and a fourth surface 2202 disposed opposite to each other, with the third surface 2201 closer to the winding center axis O than the fourth surface 2202. The third active material layer 221 is disposed on the third surface 2201, and the fourth active material layer 222 is disposed on the fourth surface 2202. The second current collector 220 may contain copper, nickel, or carbon-based conductive materials. In some embodiments, when the second electrode 22 is a positive electrode, the second current collector 220 contains aluminum foil, which has relatively weak strength but good conductivity. Both the third active material layer 221 and the fourth active material layer 222 contain active materials, 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.

[0142] The separator 23 includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid.

[0143] Please refer to the above as well. Figure 3 and Figure 4 The electrochemical device 100 also includes a first conductive plate 30. Figure 3 for Figure 1B The electrochemical device shown is a cross-sectional view along line III-III. Figure 4 for Figure 3 The enlarged view of the electrochemical device shown at point A. (Combined with...) Figure 1A and Figure 1B It can be seen that when the cross-section of the electrochemical device 100 is drawn along III-III, this cross-section passes through the first conductive plate 30, that is... Figure 3 and Figure 4 The cross-section shown includes a first conductive plate 30. The first conductive plate 30 includes a first conductive region 31 and a second conductive region 32 connected to each other. The second conductive region 32 is bent relative to the first conductive region 31. (Refer to reference...) Figure 2B and Figure 2C As shown, the first conductive region 31 is connected to the first electrode 21 (e.g., the first current collector 210 connected to the first electrode 21), and the first conductive region 31 can extend out of the first electrode 21 along the first direction X. The second conductive region 32 is connected to the first wall 11. In the first direction X, the second conductive region 32 is disposed between the first wall 11 and the electrode assembly 20. The second conductive region 32 includes a first end 321 connected to the first conductive region 31 and a second end 322 away from the first end 321, and the second conductive region 32 extends from the first end 321 along the second direction Y. For example, the second direction Y is the direction from the first end 321 to the second end 322. Viewed from a third direction Z perpendicular to the first direction X and the second direction Y, the first conductive plate 30 bends at the first end 321, and the first conductive region 31 can be approximately perpendicular to the second conductive region 32. Viewed from the first direction X, the bend between the first conductive region 31 and the second conductive region 32 overlaps with the electrode assembly 20. As shown... Figure 4 As shown, the first conductive plate 30 includes a first surface 301 facing the housing 10 and a second surface 302 facing the electrode assembly 20. Because the first conductive plate 30 is bent, the first surface 301 and the second surface 302 are not planar, and the first surface 301 and the second surface 302 are the bent surfaces.

[0144] In some embodiments, the first current collector 210 includes a first portion 2100, the first surface 2101 of the first portion 2100 being separate from the first active material layer 211, and the first conductive region 31 being connected to the first surface 2101 of the first portion 2100. By setting the first conductive region 31 to be connected to the first portion 2100 separate from the first active material layer 211, the influence of the first conductive region 31 on the energy density of the electrochemical device 100 in the second direction Y is reduced, and the influence of the first conductive region 31 on the overall flatness of the electrode assembly 20 is also reduced. Further, in the second direction Y, the first conductive region 31 may be provided on the surface of the first portion 2100 facing the sidewall 13 (i.e., the first surface 2101 of the first portion 2100). By setting the first conductive area 31 on the surface of the first portion 2100 facing the side wall 13, the obstruction of the first portion 2100 reduces the possibility of burrs in the first conductive area 31 (e.g., burrs can be formed during the cutting process of the first conductive plate 30, but this application is not limited to this) piercing the separator 23, causing the first electrode 21 and the second electrode 22 to directly contact and cause a short circuit. The second surface 2102 of the first portion 2100 can also be separated from the second active material layer 212, and the first portion 2100 can then be the empty foil area at the tail of the first electrode 21. To improve the connection strength, the first conductive area 31 can be welded to the first surface 2101 of the first portion 2100, and the second conductive area 32 can be welded to the first wall 11.

[0145] In some embodiments, when viewed from the first direction X, the second conductive region 32 overlaps with the winding center axis O of the electrode assembly 20. Since the second conductive region 32 extends to overlap with the winding center axis O, it has a larger size in the second direction Y, which is beneficial for improving the connection strength between the second conductive region 32 and the first wall 11.

[0146] Please refer to Figure 5 The electrochemical device 100 also includes a second conductive plate 40. Figure 5 for Figure 1B The electrochemical device shown is a cross-sectional view along VV. (Combined with...) Figure 1A and Figure 1B It can be seen that when the cross-section of the electrochemical device 100 is taken along VV, the cross-section passes through the second conductive plate 40, that is... Figure 5The cross-section shown includes a second conductive plate 40. The second conductive plate 40 includes a third conductive region 41 and a fourth conductive region 42 connected to each other. The third conductive region 41 is connected to a second electrode 22 (e.g., a second current collector 220 connected to the second electrode 22), and the third conductive region 41 extends outward from the second electrode 22 along a first direction X. The fourth conductive region 42 is connected to a conductive element 14 (e.g., a conductive portion 141 connected to the conductive element 14). In the first direction X, the fourth conductive region 42 is disposed between the second wall 12 and the electrode assembly 20. The fourth conductive region 42 includes a third end 421 connected to the third conductive region 41 and a fourth end 422 opposite to the third end 421, and the fourth conductive region 42 extends from the third end 421 along a second direction Y.

[0147] In some embodiments, the second current collector 220 includes a second portion 2200, the third surface 2201 of the second portion 2200 being separate from the third active material layer 221, and the third conductive region 41 being connected to the third surface 2201 of the second portion 2200. By setting the third conductive region 41 to be connected to the second portion 2200 separate from the third active material layer 221, the influence of the third conductive region 41 on the energy density of the electrochemical device 100 in the second direction Y is reduced, and the influence of the third conductive region 41 on the overall flatness of the electrode assembly 20 is also reduced. The fourth surface 2202 of the second portion 2200 can also be separate from the fourth active material layer 222, and the second portion 2200 can then be the empty foil area at the tail of the second electrode 22. To improve the connection strength, the third conductive region 41 can be welded to the third surface 2201 of the second portion 2200, and the fourth conductive region 42 can be welded to the conductive element 14.

[0148] By providing a second conductive region 32 connecting to the first wall 11 and a fourth conductive region 42 connecting to the conductive element 14, the first wall 11 and the conductive element 14 exhibit opposite polarities, enabling the electrochemical device 100 to supply power to external components (not shown). Specifically, when the first electrode 21 is a negative electrode and the second electrode 22 is a positive electrode, the first wall 11, side wall 13, and second wall 12 are all negatively polarized, while the conductive element 14 is positively polarized.

[0149] like Figures 3 to 5As shown, the electrochemical device 100 further includes a first layer 50 comprising an insulating material. In the first direction X, the first layer 50 is disposed between the electrode assembly 20 and the second conductive region 32. The first layer 50 serves to isolate the electrode assembly 20 from the first wall 11, reducing the possibility of a short circuit caused by direct contact between the second electrode 22 and the first wall 11. The first layer 50 may also cover burrs on the second conductive region 32 (e.g., burrs may be formed during the cutting process of the first conductive plate 30, but this application is not limited thereto), reducing the possibility of the burrs piercing the separator 23, causing direct contact between the first electrode 21 and the second electrode 22, resulting in a short circuit. The insulating material of the first layer 50 may be selected from at least one of polypropylene, polyethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, or polyethylene glycol.

[0150] like Figure 4 As shown, in some embodiments, the first layer 50 includes a fifth surface 501 facing the first wall 11 and a sixth surface 502 facing the electrode assembly 20. The fifth surface 501 and the sixth surface 502 are disposed opposite to each other. The fifth surface 501 of the first layer 50 includes a first recess 503, and the first recess 503 does not penetrate the sixth surface 502 along the first direction X. At least a portion of the second conductive region 32 is disposed within the first recess 503, and the second surface 302 of the second conductive region 32 is in contact with the bottom surface of the first recess 503. In the first direction X, the second surface 302 of the second conductive region 32 is located between the fifth surface 501 and the sixth surface 502 of the first layer 50. To facilitate welding the second conductive region 32 to the first wall 11, in the first direction X, the first surface 301 of the second conductive region 32 may be further away from the electrode assembly 20 than the fifth surface 501 of the first layer 50. Figure 4 As shown, a portion of the second conductive region 32, including the second end 322, can be disposed within the first recess 503. The first layer 50 is in contact with the second conductive region 32 at the first recess 503. Thus, while maintaining the thickness of the first layer 50, the total thickness of the second conductive region 32 and the first layer 50 in the first direction X can be reduced, thereby improving energy density. Further details can be found in the attached diagram. Figure 6 and Figure 7 Viewed from the first direction X, the edge of the first recess 503 may overlap with the edge of the second conductive area 32. Thus, while allowing part of the second conductive area 32 to be disposed within the first recess 503, the impact of an excessively large first recess 503 on the insulating effect of the first layer 50 is also reduced, thereby ensuring that the first layer 50 can fully isolate the electrode assembly 20 and the first wall 11 after the first recess 503 is formed.

[0151] Please see Figure 6 and Figure 7Viewed from the first direction X, the first layer 50 includes a first side 51 that extends curved along the edge of the electrode assembly 20 and a second side 52 connected to the first side 51. Figure 6 and Figure 7 The outermost layer of the electrode assembly 20, namely the insulating film 23, is shown. The insulating film 23 is the edge of the electrode assembly 20 when viewed from the first direction X. The edge of the electrode assembly 20 when viewed from the first direction X can be divided into a first segment 20a and a second segment 20b (when viewed from the first direction X, the edge of the electrode assembly 20 and the second side 52 are compared with the first intersection point P1 and the second intersection point P2, which divide the edge of the electrode assembly 20 into the first segment 20a and the second segment 20b). The first side 51 is positioned opposite to the first segment 20a, and the second side 52 is positioned opposite to the second segment 20b. In this application, the first side 51 extends curvedly along the edge of the electrode assembly 20, meaning that the extension direction of the first side 51 is consistent with or substantially consistent with the extension direction of the first segment 20a. When the edge of the electrode assembly 20 is approximately circular when viewed from the first direction X, the first segment 20a is an arc segment, that is, part of a curved circumference, and the first side 51 can also be correspondingly set as an arc segment. When the edge shape of the electrode assembly 20 changes, the shape of the first side 51 can also be different. For example... Figure 6 and Figure 7 As shown, in order to ensure that the first layer 50 fully isolates the second electrode 22 from the first wall 11, when viewed from the first direction X, the first side 51 can be located outside the electrode assembly 20. In this case, the radius of the circumference defined by the first side 51 is larger than the radius of the circumference defined by the first segment 20a, and the distance between the first side 51 and the first segment 20a can remain consistent or substantially consistent along the extension direction of the first side 51. In other embodiments, when viewed from the first direction X, the first side 51 can also approximately coincide with the first segment 20a.

[0152] Viewed from the first direction X, the second side 52 overlaps with the electrode assembly 20, and the second side 52 is farther from the edge of the electrode assembly 20 than the first side 51. Therefore, the second side 52 deviates from the circumference defined by the first side 51, and the second side 52 is located inside the circumference defined by the first side 51. The second side 52 can be a straight line or may include a curved portion. In some embodiments, the second side 52 is a straight line and extends along a third direction Z. Viewed from the first direction X, the first end 321 of the second conductive region 32 is spaced apart from the first layer 50 in the second direction Y, and the second end 322 overlaps with the first layer 50. Viewed from the first direction X, the second conductive region 32 extends from the first end 321 along the second direction Y beyond the second side 52. Since the second side 52 is farther from the edge of the electrode assembly 20 than the first side 51, and the second side 52 deviates from the circumference defined by the first side 51, the first layer 50 has a notch C when viewed from the first direction X, and the second side 52 is the edge of the notch C. Viewed from the first direction X, the first end 321 of the second conductive region 32 can be located within the notch C, thereby reducing the possibility of the first end 321 contacting and rubbing against the sidewall 13.

[0153] like Figure 6 and Figure 7 As shown, in some embodiments, the dimension of the second side 52 in the third direction Z is d2, and the dimension of the second conductive region 32 in the third direction Z is d, then d2>d. Therefore, the first layer 50 can fully cover the second conductive region 32, reducing the possibility that burrs in the second conductive region 32 will pierce the isolation film 23, causing the first electrode 21 and the second electrode 22 to directly contact and short-circuit. Moreover, since the second side 52 is relatively large, the first layer 50 can fully isolate the second electrode 22 and the first wall 11, reducing the possibility that the second electrode 22 and the first wall 11 will directly contact and short-circuit.

[0154] The measurement steps for d and d2 can be as follows: (1) Using X-rays to perform two-dimensional projection and scanning tests on the electrochemical device 100 from the first direction X. The instrument can be an instrument or device known to those skilled in the art (e.g., GEPhoenix vtomex S device) to obtain a CT image; (2) Using calipers or other suitable measuring tools to directly measure the values ​​of d and d2.

[0155] The measurement steps for d and d2 can also be: (1) Discharge the electrochemical device 100 to 2.75V at 0.2C; (2) Cut the side wall 13 of the shell 10 near the first edge 131 along a section perpendicular to the first direction X. After most of the side wall 13 is separated from the first wall 11, open the first wall 11 relative to the first layer 50. At this time, the second conductive area 32 is still connected to the first wall 11; (3) Measure the values ​​of d and d2 directly using calipers or other suitable measuring tools.

[0156] The measurement steps for d and d2 can also be as follows: (1) Discharge the electrochemical device 100 to 2.75V at 0.2C; (2) Prepare a resin composition, which is made of a crystal resin matrix (such as epoxy resin), catalyst and curing agent in a certain proportion; (3) Pour the resin composition into a mold, place the electrochemical device 100 in the mold, and continue to slowly pour the resin composition in so that the electrochemical device 100 is completely immersed in the resin composition; (4) Take out the electrochemical device 100 and let it stand until the resin composition solidifies; (5) Grind the first wall 11 of the shell 10 until the second conductive area 32 is exposed on the grinding surface; (6) Use calipers or other suitable measuring tools to directly measure the values ​​of d and d2.

[0157] like Figure 4 and Figure 7As shown, the electrochemical device 100 further includes a second layer 60 comprising an insulating material. The second layer 60 covers the first conductive plate 30, and when viewed from the first direction X, the second layer 60 covers the notch C, thereby further reducing the possibility of a short circuit that may be caused by the notch C in the first layer 50. The second layer 60 includes a first region 61 covering the second conductive region 32. When viewed from the first direction X, the first region 61 covers the notch C. In some embodiments, the second layer 60 covers the second surface 302 of the first conductive plate 30, and the first region 61 is disposed between the second conductive region 32 and the electrode assembly 20 in the first direction X. The first region 61 further isolates the electrode assembly 20 from the first wall 11, thereby reducing the possibility of a short circuit caused by direct contact between the second electrode 22 and the first wall 11. When the first region 61 is disposed between the second conductive region 32 and the electrode assembly 20 in the first direction X, the second layer 60 can also cover the burrs of the second conductive region 32, reducing the possibility that the burrs will pierce the separator 23, causing direct contact between the first electrode 21 and the second electrode 22, resulting in a short circuit. That is, the first region 61 of the second layer 60 is used in conjunction with the first layer 50 to jointly isolate the electrode assembly 20 and the first wall 11, and to jointly cover the burrs of the second conductive region 32, reducing the possibility of short circuits. In this embodiment, the first region 61 includes a first partition 611 and a second partition 612 connected to each other. Viewed from the first direction X, the first partition 611 is located between the second conductive region 32 and the electrode assembly 20, and the first partition 611 overlaps with the notch C. Viewed from the first direction X, the second partition 612 overlaps with the first layer 50. By setting the second partition 612 to overlap with the first layer 50, the first region 61 can fully cover the notch C. The second partition 612 may also be provided within the first recess 503. The insulating material of the second layer 60 may be selected from at least one of polypropylene, polyethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, or polyethylene glycol. The second layer 60 may be a single-sided or double-sided adhesive containing insulating material. In other embodiments, the second layer 60 may also be a ceramic coating.

[0158] like Figure 4 and Figure 7 As shown, the distance between the second side 52 and the sidewall 13 in the second direction Y is a first distance L. The second partition 612 has a first end 6120 that is opposite to the first partition 611 in the second direction Y. The dimension of the first end 6120 and the sidewall 13 in the second direction Y is d1, where L < d1. It can be understood that L is the distance between the second side 52 and the portion of the sidewall 13 located on the side opposite to the second side 52 in the notch C in the second direction Y; d1 is the distance between the first end 6120 and the portion of the sidewall 13 located on the side opposite to the second side 52 in the notch C in the second direction Y. L and d1 can be measured using a similar measurement procedure to d and d2.

[0159] like Figure 7 As shown, in some embodiments, the dimension of the second side 52 in the third direction Z is d2, and the dimension of the first region 61 in the third direction Z is d3, where d2 < d3. This allows the first region 61 to fully cover the notch C in the third direction Z, thereby enabling the first region 61 to work with the first layer 50 to jointly isolate the electrode assembly 20 and the first wall 11, and to jointly cover the burrs of the second conductive region 32, reducing the possibility of a short circuit.

[0160] Furthermore, in some embodiments, the second layer 60 may also include a second region 62 connecting the first region 61. The second region 62 is used to cover the burrs of the first conductive region 31, further reducing the possibility that the burrs will pierce the isolation film 23, causing the first electrode 21 and the second electrode 22 to come into direct contact and cause a short circuit. It is understood that, for the sake of simplicity, Figure 7 Only the first region 61 of the second layer 60 is shown; the second region 62 of the second layer 60 is not shown.

[0161] Considering that the bend between the first conductive region 31 and the second conductive region 32 overlaps with the electrode assembly 20 when viewed from the first direction X, this application sets the second side 52 to be further away from the edge of the electrode assembly 20 than the first side 51, so that the second side 52 can avoid the bend between the first conductive region 31 and the second conductive region 32. Thus, when the electrochemical device 100 suffers mechanical abuse (such as impact or drop), the interference and compression of the first layer 50 on the bend between the first conductive region 31 and the second conductive region 32 can be reduced, thereby reducing the possibility of the bend of the first conductive plate 30 breaking under stress and causing the electrochemical device 100 to fail. It also reduces the possibility that the sharp point generated after the first conductive plate 30 breaks will pierce the separator 23, causing the first electrode 21 and the second electrode 22 to directly contact and trigger a short circuit. Therefore, the reliability and service life of the electrochemical device 100 are improved. When the electrochemical device 100 is a coin cell, since coin cells are generally small in size, in this implementation, it is not necessary to reduce the compression of the first layer 50 on the bending point of the first conductive plate 30 by reducing the size of the electrode assembly 20 (for example, by reducing the size of the electrode assembly 20, the gap between the electrode assembly 20 and the housing 10 is increased accordingly, which can provide a larger buffer space for the electrode assembly 20 in the event of mechanical abuse, and reduce the compression of the first layer 50 on the bending point of the first conductive plate 30), which is beneficial to improve the energy density.

[0162] Furthermore, by providing a first region 61 of the second layer 60 to cover the notch C, the first region 61, together with the first layer 50, can isolate the electrode assembly 20 and the first wall 11, reducing the possibility of short circuits that may occur due to the notch C in the first layer 50. In addition, since the first region 61 covers the second side 52 of the first layer 50, the second layer 60 can also reduce the possibility of warping at the second side 52, and make the first layer 50 less likely to move within the housing 10.

[0163] Please refer to the following: Figure 4 , Figure 7 and Figure 8 In some embodiments, the second layer 60 is a single-sided adhesive bonded to the first conductive plate 30. The second layer 60 includes a stacked adhesive layer 601 and a substrate 602. The adhesive layer 601 contains an insulating material. The substrate 602 is bonded to the first conductive plate 30 through the adhesive layer 601. By providing the second layer 60 to cover the gap C of the first layer 50, since the second layer 60 is not bonded to the electrode assembly 20, the electrolyte located between the first layer 50 and the first wall 11 after liquid injection can flow through the gap C and fully wet the electrode assembly 20, thereby improving the interface during cycling, reducing capacity decay caused by lithium plating, black spots, purple spots, etc., and improving the cycling performance of the electrochemical device 100. Furthermore, in some embodiments, 0.4d1 < L < d1 can be set, thereby reducing the possibility that when the L value is too small, the size of the notch C is small, and the electrolyte located between the first layer 50 and the first wall 11 after liquid injection is not easy to flow through the notch C and fully wet the electrode assembly 20. Therefore, the wetting effect of the electrode assembly 20 is improved, thereby improving the interface during cycling and reducing capacity decay caused by lithium plating, black spots, purple spots, etc. The substrate 602 is made of at least one of polyimide or polyethylene terephthalate. The insulating material of the adhesive layer 601 can be selected from at least one of butadiene, isoprene, styrene, methyl methacrylate, butyl methacrylate, isooctyl acrylate, or butyl acrylate.

[0164] Because the second layer 60 is made of single-sided adhesive bonded to the first conductive plate 30, and the relationship between d1 and L can be further rationally configured, the electrolyte located between the first layer 50 and the first wall 11 after injection can flow through the notch C and fully wet the electrode assembly 20. Therefore, in some embodiments, the first layer 50 can be configured to cover the cavity S2 of the electrode assembly 20 when viewed from the first direction X. That is, this application does not require an opening in the first layer 50 corresponding to the cavity S2 in order to fully wet the electrode assembly 20 with electrolyte, thereby reducing the possibility that solder marks or slag in the first conductive area 31 will contact the second electrode 22 through the aforementioned opening and affect the lifespan of the electrochemical device 100.

[0165] like Figure 3 and Figure 4As shown, in some embodiments, the electrochemical device 100 further includes a third layer 70 comprising an insulating material. The third layer 70 covers the first surface 301 of the first conductive plate 30. Viewed from the first direction X, the third layer 70 covers at least a portion of the notch C, thereby further reducing the possibility of a short circuit that may be caused by the notch C in the first layer 50. The third layer 70 includes a third region 71 located in the first direction X between the second conductive region 32 and the first wall 11. Viewed from the first direction X, the third region 71 covers at least a portion of the notch C. The third region 71 further isolates the electrode assembly 20 from the first wall 11, thereby reducing the possibility of a short circuit caused by direct contact between the second electrode 22 and the first wall 11. That is, the third region 71 of the third layer 70 works in conjunction with the first layer 50 to isolate the electrode assembly 20 from the first wall 11, reducing the possibility of a short circuit. In this embodiment, the third region 71 includes a third partition 711 and a fourth partition 712 connected together. Viewed from the first direction X, the third partition 711 overlaps with the notch C. Viewed from the first direction X, the fourth partition 712 overlaps with the first layer 50. By setting the fourth partition 712 to overlap with the first layer 50, the third region 71 and the first region 61 can jointly and fully cover the gap C, further reducing the possibility of a short circuit. The insulating material of the third layer 70 can be selected from at least one of polypropylene, polyethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, or polyethylene glycol.

[0166] The fourth partition 712 has a second end 7120 that is opposite to the third partition 711 in the second direction Y. The dimension of the second end 7120 and the sidewall 13 in the second direction Y is d5, where L < d5. In some embodiments, d5 may be approximately equal to d1. It can be understood that d5 is the distance in the second direction Y between the second end 7120 and the portion of the sidewall 13 located on the side opposite to the second side 52 of the notch C.

[0167] like Figure 4 and Figure 6 As shown, in some embodiments, the radius of the first wall 11 is R (it can be understood that...). Figure 6 If the radius R of the sidewall 13 shown is the same as the radius of the first wall 11, then d5 < 0.4R. In this way, the influence of the third region 71 on the connection area (e.g., the welding area) between the second conductive plate 40 and the first wall 11 can be reduced, that is, the possibility of the third region 71 interfering with the above-mentioned connection area and causing the connection area to fail can be reduced.

[0168] In some embodiments, the dimension of the second side 52 in the third direction Z is d2, and the dimension of the third region 71 in the third direction Z is d4, where d2 < d4. This allows the third region 71 to fully cover the gap C in the third direction Z, thereby enabling the third region 71 to work in conjunction with the first layer 50 to jointly isolate the electrode assembly 20 and the first wall 11, reducing the possibility of a short circuit. In some embodiments, d4 may be approximately equal to d3.

[0169] like Figure 4 and Figure 6 As shown, further, in some embodiments, the third layer 70 may also include a fourth region 72 connecting the third region 71. For example... Figure 4 As shown, in the second direction Y, the fourth region 72 is located on the first surface 301 of the first conductive region 31. The fourth region 72 is used to cover burrs or solder marks on the first conductive region 31. The third layer 70 can be a single-sided or double-sided adhesive containing insulating material. In other embodiments, the third layer 70 can also be a ceramic coating. It is understood that, for simplicity... Figure 6 Only the third region 71 of the third layer 70 is shown; the fourth region 72 of the third layer 70 is not shown.

[0170] like Figures 3 to 5 As shown, in some embodiments, the electrochemical device 100 may further include a fourth layer 80 comprising an insulating material. In the first direction X, the fourth layer 80 is disposed between the electrode assembly 20 and the sidewall 13. The fourth layer 80 reduces the likelihood of a short circuit caused by direct contact between the second electrode 22 and the sidewall 13 (e.g., burrs on the second electrode 22 piercing the outermost insulating membrane 23 and contacting the sidewall 13). Figure 2A As shown, the fourth layer 80 can be a continuous ring structure. In some embodiments, the insulating material of the fourth layer 80 can be selected from at least one of polypropylene, polyethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, or polyethylene glycol.

[0171] Please see Figure 9 Another embodiment of this application also provides an electrochemical device 200, which differs from the electrochemical device 100 described above in that the second side 52 includes a curved portion. Considering that a notch may be formed on the second side 52 when the first layer 50 is cut at the notch C, by providing a curved portion on the second side 52, the possibility of the notch further expanding and forming a crack during the installation of the first layer 50 can be reduced.

[0172] Please see Figure 10Another embodiment of this application also provides an electrochemical device 300, which differs from the electrochemical device 100 described above in that the first wall 11 and the second wall 12 are electrically isolated. For example, the side wall 13 and the second wall 12 can be integrally formed, and the second wall 12 and the side wall 13 can be bonded and fixed together by a second insulating layer 16. The second insulating layer 16 makes the first wall 11 and the side wall 13 electrically isolated, and the first wall 11 and the second wall 12 also electrically isolated.

[0173] At this time, the fourth conductive region 42 of the second conductive plate 40 is connected to the second wall 12. The first wall 11 and the second wall 12 have opposite polarities, allowing the electrochemical device 300 to supply power to external components. Specifically, when the first electrode 21 is the negative electrode and the second electrode 22 is the positive electrode, the first wall 11 and the side wall 13 are negative, and the second wall 12 is positive.

[0174] The electrochemical devices 100, 200, and 300 of this application include all devices capable of undergoing electrochemical reactions. Specifically, electrochemical devices 100, 200, and 300 include all types of primary batteries, secondary batteries, fuel cells, solar cells, and capacitors (e.g., supercapacitors). Optionally, electrochemical devices 100, 200, and 300 can be lithium secondary batteries, including lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, and lithium-ion polymer secondary batteries.

[0175] Please see Figure 11 This application also provides an electronic device 1, including the aforementioned electrochemical device 100 (or electrochemical devices 200, 300). The electronic device 1 is powered by the electrochemical device 100, and the electrochemical device 100 reduces the likelihood of breakage of the first conductive plate 30 by positioning the second side 52 further away from the edge of the electrode assembly 20 than the first side 51, thereby maintaining high reliability and service life. In one embodiment, the electronic device 1 of this application may be, but is not limited to, a laptop computer, a pen-based 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-ROM, 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, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, household large-capacity batteries, and lithium-ion capacitors, etc.

[0176] The performance of the electrochemical device 100 provided in this application will be described below through specific embodiments and comparative examples. The electrochemical device 100 is exemplified by a coin-type lithium-ion battery, and the application will be described in conjunction 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.

[0177] Example 1

[0178] (1) Preparation of the first electrode 21: The negative electrode active materials artificial graphite, conductive carbon black (Super P), and styrene-butadiene rubber (SBR) are mixed in a weight ratio of 96:1.5:2.5, and deionized water is added as a solvent to prepare a slurry with a weight percentage of 70 wt%, which is then stirred evenly. The slurry is uniformly coated on one surface of a 10 μm thick copper foil for the negative electrode current collector and dried at 110°C to obtain a negative electrode sheet with a coating thickness of 150 μm coated on one side with a negative electrode active material layer. The above steps are repeated on the other surface of the negative electrode sheet to obtain a negative electrode sheet with a double-sided coating of a negative electrode active material layer. Next, the first conductive plate 30 is welded to the exposed area of ​​the first current collector 210, and protective adhesives, such as the second layer 60 and the third layer 70, are pasted on the solder marks on both sides of the first conductive plate 30. The second layer 60 and the third layer 70 are single-sided adhesives, and the adhesive layers of the second layer 60 and the third layer 70 are both facing the first conductive plate 30.

[0179] (2) Preparation of the second electrode 22: 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. The slurry was uniformly coated on one surface of a 12 μm thick aluminum foil for the positive current collector, and then dried at 90 °C to obtain a positive electrode with a positive active material layer thickness of 100 μm. The slurry was uniformly coated on this surface, and then dried at 90 °C to obtain a positive electrode with positive active material layers coated on both sides. Next, a second conductive plate 40 was welded to the exposed area of ​​the second current collector 220, and a protective adhesive was attached to the second conductive plate 40.

[0180] (3) Preparation of electrolyte: In a dry argon atmosphere, the organic solvents ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are first mixed in a mass ratio of EC:EMC:DEC = 30:50:20. Then, lithium salt lithium hexafluorophosphate (LiPF6) is added to the organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0181] (4) Battery fabrication: The first electrode 21, the separator 23, and the second electrode 22 are sequentially stacked and wound to obtain the electrode assembly 20. The separator 23 is a polyethylene (PE) film with a thickness of 15 μm. Then, the first layer 50 and the electrode assembly 20 are sequentially placed in the receiving cavity S1 formed by the first wall 11 and the side wall 13. The first conductive plate 30 and the second conductive plate 40 are bent and welded respectively. The second side 52 of the first layer 50 is farther away from the edge of the electrode assembly 20 than the first side 51, so that the second side 52 can avoid the bending point of the first conductive plate 30. The second layer 60 extends to the first region 61 and overlaps with the first layer 50 in the first direction X, satisfying L = 0.3d1. Finally, electrolyte injection and encapsulation are performed to obtain the battery.

[0182] Examples 2-4

[0183] The difference from Example 1 lies in the relationship between L and d1.

[0184] Example 5

[0185] The difference from Embodiment 1 is that the third layer 70 is also extended to overlap with the first layer 50 in the first direction X.

[0186] Comparative Example

[0187] The difference from Example 1 is that, when viewed from the first direction X, the first region 61 of the second layer 60 does not overlap with the first layer 50, and L = 1.1d1.

[0188] Drop tests, roller drop tests, and cycle tests were conducted on the batteries of each embodiment and comparative example, and the corresponding test results are recorded in Table 1 and Table 2.

[0189] The drop test steps are as follows:

[0190] 1) Under environmental conditions of 25±5℃, charge the battery at 0.2C to the charging limit voltage; 2) Place the battery in a special drop test fixture, use a robotic arm to pick up the sample, and drop the bottom, side, and top of the battery sequentially from a height of 1.8m onto a marble slab, for a total of 3 rounds, or 9 drops; 3) After each round of drops, observe whether the battery cell is damaged or leaking, and measure the battery's open circuit voltage and internal resistance (the testing instrument is a voltage-resistance tester, manufacturer: Dongguan Lijia Precision Instruments Co., Ltd., model: LNG-SY1-0020-DQ). If the voltage is less than 3.0V, the battery is considered to have failed; if there is no damage or leakage, and the open circuit voltage is higher than 3.0V, the battery is considered not to have failed, and the dropping continues until the battery fails. Then record the number of drops performed when the battery fails.

[0191] The steps for the roller drop test are as follows:

[0192] 1) Under environmental conditions of 25±5℃, charge the battery at 0.2C to the charging limit voltage; 2) Place the battery in a special roller drop test fixture and drop it from a height of 1m at a speed of 5 revolutions / min for 500 revolutions (2 drops constitute one revolution). After every 5 revolutions of roller drops, observe whether the battery is damaged or leaking, and measure the battery's open circuit voltage and internal resistance. If the voltage is less than 3.0V, the battery is considered to have failed; if there is no damage or leakage, and the open circuit voltage is higher than 3.0V, the battery is considered not to have failed, and continue dropping until the battery fails. Then record the number of drops performed when the battery fails.

[0193] The loop test steps are as follows:

[0194] 1) Place the battery in a 25°C constant temperature chamber and let it stand for 30 minutes to allow the battery to reach a constant temperature; 2) Charge the battery at a constant current of 1C to a voltage of 3.65V, then charge it at a constant voltage of 3.65V to a current of 0.05C, and then discharge it at a constant current of 1C to a voltage of 2.5V. This is one charge-discharge cycle, and the capacity of the first discharge is 100%; 3) Repeat 1000 charge-discharge cycles, record the discharge capacity of the battery, and then calculate the capacity retention rate of the battery; 4) Observe whether the electrode assembly 20 is deformed by CT scan, then disassemble the battery and observe the interface of the first electrode 21.

[0195] Table 1

[0196]

[0197] As can be seen from the test results in Table 1, compared with the comparative example, Example 1 sets the second side 52 of the first layer 50 to be further away from the edge of the electrode assembly 20 than the first side 51, so that the second side 52 can avoid the bend of the first conductive plate 30, and the second layer 60 extends to the first region 61 and overlaps with the first layer 50 in the first direction X. Therefore, the number of drops when failure occurs in the drop test and the roller drop test is increased, that is, the battery reliability and service life of Example 1 are improved.

[0198] Table 2

[0199]

[0200] As shown in Table 2, compared to Examples 2-4, the L value of Example 1 is smaller, and the number of drops at the time of failure in the drop test and roller drop test is not significantly different. However, due to the smaller L value of Example 1, the size of the notch C is smaller. After liquid injection, the electrolyte located between the first layer 50 and the first wall 11 does not easily flow through the notch C and fully wet the electrode assembly 20. Therefore, the first electrode 21 develops slight purple spots, causing capacity decay. In Example 5, since the third layer 70 is also extended to overlap with the first layer 50 in the first direction X, the adhesive layer of the third layer 70 will at least partially adhere to the electrode assembly 20 during the drop test. This makes it difficult for the electrolyte located between the first layer 50 and the first wall 11 to flow through the notch C and fully wet the electrode assembly 20 after liquid injection. Therefore, the first electrode 21 also develops slight purple spots, causing capacity decay.

[0201] 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 a housing and an electrode assembly, the housing including a first wall and a sidewall connecting the first wall, the first wall and the sidewall forming a receiving cavity, the electrode assembly being housed within the receiving cavity, a first direction being the direction from the first wall to the electrode assembly, the electrode assembly having a wound structure, and the electrode assembly including a first electrode, a second electrode, and a separating membrane disposed between the first electrode and the second electrode; wherein, The electrochemical device further includes a first conductive plate, a first layer, and a second layer. The first conductive plate includes a first conductive region and a second conductive region connected together. The second conductive region is bent relative to the first conductive region. The first conductive region is connected to the first electrode. The second conductive region is connected to the first wall. The second conductive region includes a first end connected to the first conductive region and a second end disposed opposite to the first end. The second conductive region extends from the first end along a second direction perpendicular to the first direction. The first layer comprises an insulating material and is disposed between the electrode assembly and the second conductive region in the first direction; Viewed from the first direction, the first layer includes a first side extending curved along the edge of the electrode assembly and a second side connected to the first side, the second side overlapping the electrode assembly, and the second side being further away from the edge of the electrode assembly than the first side, thus forming a gap in the first layer; viewed from the first direction, the second end overlaps with the first layer; The second layer contains an insulating material and includes a first region covering the second conductive area. The first region includes a first partition and a second partition that are connected to each other. When viewed from the first direction, the first partition covers the gap, and the second partition overlaps with the first layer.

2. The electrochemical device as claimed in claim 1, wherein, Viewed from the first direction, the first end is located within the notch.

3. The electrochemical device as described in claim 1, wherein, The surface of the first layer facing the first wall includes a first recess, and the first layer is in contact with the second conductive region at the first recess.

4. The electrochemical device as claimed in claim 1, wherein, The second side includes a curved portion.

5. The electrochemical device as claimed in claim 1, wherein, Define a third direction perpendicular to the first direction and the second direction, the dimension of the second side in the third direction is d2, the dimension of the second conductive area in the third direction is d, and d2>d.

6. The electrochemical device as claimed in claim 1, wherein, The first electrode includes a first current collector and a first active material layer disposed on the surface of the first current collector. The first current collector includes a first portion that is separated from the first active material layer, and the first conductive region is connected to the first portion.

7. The electrochemical device as claimed in claim 6, wherein, In the second direction, the first conductive region is disposed on the surface of the first portion facing the sidewall.

8. The electrochemical device as claimed in claim 1, wherein, The first region is located between the second conductive region and the electrode assembly in the first direction.

9. The electrochemical device as claimed in claim 8, wherein, The second layer also includes a second region that connects to the first region, and the second region covers the first conductive region.

10. The electrochemical device as claimed in claim 9, wherein, The electrochemical device further includes a third layer comprising an insulating material, the third layer comprising a third region disposed in the first direction between the second conductive region and the first wall, the third region comprising a third partition and a fourth partition connected together, the third partition covering the gap when viewed from the first direction, and the fourth partition overlapping the first layer.

11. The electrochemical device of claim 10, wherein, The third layer further includes a fourth region connecting the third region, and in the second direction, the first conductive region is disposed between the second region and the fourth region.

12. The electrochemical device as claimed in claim 1, wherein, The second layer includes a laminated adhesive layer and a substrate, the adhesive layer containing the insulating material, and the substrate being bonded to the first conductive plate via the adhesive layer.

13. The electrochemical device of claim 12, wherein, The electrochemical device satisfies at least one of the following conditions: The material of the substrate is selected from at least one of polyimide or polyethylene terephthalate; The insulating material of the adhesive layer is selected from at least one of butadiene, isoprene, styrene, methyl methacrylate, butyl methacrylate, isooctyl acrylate, or butyl acrylate.

14. The electrochemical device of claim 10, wherein, The fourth partition includes a second end that is away from the third partition in the second direction, the second end and the sidewall having a dimension of d5 in the second direction, and the radius of the first wall being R, where d5 < 0.4R.

15. The electrochemical device as claimed in claim 1, wherein, Define a third direction perpendicular to the first direction and the second direction. The dimension of the second side in the third direction is d2, and the dimension of the first region in the third direction is d3, where d2 < d3.

16. The electrochemical device as claimed in claim 1, wherein, The distance between the second side and the sidewall in the second direction is a first distance L. The second partition includes a first end that is away from the first partition in the second direction. The dimension of the first end and the sidewall in the second direction is d1, where 0.4d1 < L < d1.

17. The electrochemical device of claim 1, wherein, Viewed from the first direction, the second conductive area overlaps with the winding center axis of the electrode assembly.

18. The electrochemical device of claim 1, wherein, The electrode assembly has a cavity at the starting end of its winding, and when viewed from the first direction, the first layer covers the cavity.

19. The electrochemical device of claim 1, wherein, The housing further includes a second wall connected to the side wall and disposed opposite to the first wall. The second wall is provided with a conductive element electrically insulated from the second wall. The electrode assembly further includes a second conductive plate electrically connected to the second electrode sheet. The second conductive plate is connected to the conductive element.

20. The electrochemical device of claim 1, wherein, The electrochemical device is a coin cell, and when viewed from the first direction, the edge of the electrode assembly is roughly circular.

21. An electronic device comprising an electrochemical device as claimed in any one of claims 1 to 20.

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