Electrochemical device and electrically powered equipment comprising the same

Abstract

An electrochemical device and an electrical device comprising the same are disclosed. The electrochemical device includes a housing, an electrode assembly, a first insulating layer, and an electrolyte, wherein the electrode assembly and the electrolyte are housed within the housing. The electrode assembly includes a plurality of electrodes stacked along a first direction and a first insulating membrane disposed between the plurality of electrodes. The electrode assembly also includes a first surface and a second surface opposite each other in the first direction, and a first end face connecting the first surface and the second surface. The first insulating layer is bonded to the first surface, the second surface, and the first end face. The first insulating membrane includes a substrate layer and a first coating layer spaced apart on the substrate layer facing adjacent electrodes.

Description

Technical Field

[0001] This application relates to the field of energy storage devices, and in particular to an electrochemical device and an electrical appliance containing the same. Background Technology

[0002] Electrochemical devices (such as lithium-ion batteries) are widely used in electric vehicles and consumer electronics due to their advantages such as high energy density, high output power, long cycle life, and low environmental pollution. However, electrochemical devices may pose safety risks, such as fire, when subjected to abnormal conditions such as compression, impact, or puncture. Summary of the Invention

[0003] One objective of this application is to provide a battery that has good cycle performance and reduces the risk of internal short circuits in electrochemical devices.

[0004] This application provides an electrochemical device including a housing, an electrode assembly, a first insulating layer, and an electrolyte, wherein the electrode assembly and the electrolyte are housed within the housing. The electrode assembly includes a plurality of electrodes stacked along a first direction and a first insulating membrane disposed between the plurality of electrodes. The electrode assembly also includes a first surface and a second surface opposite each other in the first direction, and a first end face connecting the first surface and the second surface. The first insulating layer is bonded to the first surface, the second surface, and the first end face. The first insulating membrane includes a substrate layer and a first coating layer spaced apart on the surface of the substrate layer facing adjacent electrodes.

[0005] This application provides a first insulating layer connecting the first surface, second surface, and first end face of the electrode assembly. The first insulating layer binds the electrode assembly in a first direction, reducing the risk of internal short circuits caused by the shrinkage of the first separator and improving safety performance. However, using the first insulating layer to bind the electrode assembly in the first direction may reduce the gap between the first separator and adjacent electrodes, thereby reducing the space available for electrolyte transport and resulting in poor electrolyte wetting. This application provides a first separator comprising multiple spaced-apart first coatings, with the gap between adjacent first coatings providing space for electrolyte transport. This improves electrolyte wetting, alleviates the lithium plating problem on the electrodes caused by poor electrolyte wetting, and improves cycle performance. Therefore, the electrochemical device of this application has high cycle performance while maintaining safety.

[0006] In some possible implementations, the first coating is strip-shaped, and the substrate layer includes two opposing sides in a second direction perpendicular to the first direction, with multiple first coatings arranged at an angle relative to the opposing sides. Therefore, the adhesive force between the first coating and adjacent electrodes is continuously distributed along the edges of the electrode assembly, improving the electrode assembly's resistance to deformation and enhancing cycle performance.

[0007] In some possible implementations, when viewed along the first direction, the angle between the first coating and the side is θ1, where 25° ≤ θ1 ≤ 65°. When the angle θ1 is within this range, the adhesion between the first coating and the edge of the electrode can be maintained, curbing edge deformation of the electrode and thus improving cycle performance.

[0008] In some possible implementations, when viewed along the first direction, the width of the first coating is D1, and the spacing between two adjacent first coatings is D2, where 0.3D2≤D1≤0.5D2. When D1>0.5D2, given a fixed electrode area, D2 is relatively small, reducing the space available for electrolyte transport. Poor electrolyte wetting exacerbates the lithium plating problem on the electrode, affecting cycle performance. When D1<0.3D2, the bonding area between the first coating and the electrode decreases, reducing adhesion and deformation resistance, thus affecting cycle performance.

[0009] In some possible implementations, the first separator further includes multiple second coatings, which are spaced apart on the surface of the substrate layer opposite to the multiple first coatings. The gap between two adjacent second coatings provides space for electrolyte transport, improving electrolyte wetting and further mitigating the problem of lithium plating on the electrode caused by poor electrolyte wetting, thereby improving cycle performance.

[0010] In some possible implementations, the first coating and the second coating are intersecting at opposite angles, so that the gaps between two adjacent first coatings and the gaps between two adjacent second coatings are staggered, which further improves the electrolyte wetting effect, further improves the problem of lithium plating on the electrode caused by poor electrolyte wetting, and improves cycle performance.

[0011] In some possible implementations, the first separator further includes multiple first portions located among the multiple electrodes, and second and third portions located outside the multiple electrodes and opposite each other in a first direction. Each first portion is disposed between two adjacent electrodes, and the multiple first, second, and third portions are configured integrally to form a wound structure. The first separator is configured as a wound structure, binding the multiple electrodes in multiple different directions, eliminating the need for an additional insulating layer to bind the multiple electrodes in a specific direction. Furthermore, the first insulating layer is connected to the second and third portions of the first separator, increasing the adhesion between the first insulating layer and the electrode assembly, reducing the risk of the first insulating layer detaching, and thus reducing the risk of internal short circuits caused by shrinkage of the first separator.

[0012] In some possible implementations, in a third direction perpendicular to both the first and second directions, the width of the electrode assembly is W1, and the width of the first insulating layer is W2, where 0.7W1≤W2≤W1. When the widths W1 and W2 of the electrode assembly and the first insulating layer are within this range, the adhesion between the first insulating layer and the first end face can be maintained, reducing the risk of internal short circuits caused by shrinkage of the first insulating membrane and improving safety performance.

[0013] In some possible implementations, 0.7W1 ≤ W2 ≤ 0.95W1. In some possible implementations, 0.85W1 ≤ W2 ≤ 0.95W1.

[0014] In some possible implementations, the first coating includes a first inorganic particle layer and a first adhesive layer. The first inorganic particle layer is in contact with the substrate layer, and the adhesive layer is disposed on the surface of the inorganic particle layer facing away from the substrate layer and is bonded to the adjacent electrode. The first adhesive layer bonds to the electrode, improving the interfacial adhesion between the first separator and the electrode, reducing expansion and deformation during gas generation inside the electrochemical device, and improving cycle performance.

[0015] In some possible implementations, the first coating comprises inorganic particles and a binder.

[0016] In some possible implementations, the electrochemical device further includes a second insulating layer, and the electrode assembly includes a second end face connected between the first and second surfaces. The length direction of the electrode assembly is defined as a second direction, and the first and second surfaces are opposite each other in the second direction. The second insulating layer is connected to the first surface, the second surface, and the second end face. Providing a second insulating layer connecting the first surface, the second surface, and the second end face of the electrode assembly reduces the risk of internal short circuits caused by the shrinkage of the first insulating membrane near the second end face.

[0017] In some possible implementations, the first insulating layer is single-sided or double-sided adhesive.

[0018] In some possible implementations, the second insulating layer is a single-sided or double-sided adhesive.

[0019] In some possible implementations, the electrochemical device further includes a first metal plate and a second metal plate, both of which are connected to the electrode assembly; in a third direction perpendicular to the first direction, the electrode assembly further includes a second end face opposite to the first end face, and the first metal plate and the second metal plate extend out of the electrode assembly from the second end face.

[0020] In some possible implementations, the shell is a packaging bag.

[0021] This application also provides an electrical device, including any of the above-mentioned electrochemical devices. Attached Figure Description

[0022] 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:

[0023] Figure 1 A first-view view of an electrochemical device provided in an embodiment of this application;

[0024] Figure 2 for Figure 1 A first-direction view of the electrode assembly of the electrochemical device shown, viewed from the side where the first surface is located.

[0025] Figure 3 for Figure 2 The electrode assembly shown is viewed from the side where the second surface is located in a first-direction view.

[0026] Figure 4 for Figure 2 A second-direction view of the electrode assembly shown;

[0027] Figure 5 for Figure 2 The electrode assembly shown is a cross-sectional view along VV.

[0028] Figure 6 for Figure 4 The electrode assembly shown is a cross-sectional view along VI-VI;

[0029] Figure 7 for Figure 6 A first view of the first insulating membrane of the electrode assembly shown from the side closest to the first surface of the electrode assembly;

[0030] Figure 8 for Figure 7 The first isolation membrane shown is viewed from the side closest to the second surface of the electrode assembly in a first direction.

[0031] Figure 9 A first-direction view of a first isolation membrane provided in another embodiment of this application;

[0032] Figure 10 A second view of an electrode assembly provided in another embodiment of this application;

[0033] Figure 11 A second view of an electrode assembly provided in yet another embodiment of this application;

[0034] Figure 12 This is a schematic diagram of the structure of an electrical device provided in an embodiment of this application.

[0035] Explanation of main component symbols

[0036] Electrochemical device 100

[0037] Casing 10

[0038] Electrode assembly 20

[0039] First metal plate 30

[0040] Second metal plate 40

[0041] First separating membrane 23

[0042] First film 21

[0043] Second pole piece 22

[0044] First current collector 211

[0045] First active material layer 212

[0046] Second current collector 221

[0047] Second active material layer 222

[0048] First surface 201

[0049] Second surface 202

[0050] Second end face 203

[0051] First end face 204

[0052] First side view 205

[0053] Second side 206

[0054] First insulating layer 50

[0055] Fourth insulating layer 60

[0056] Third insulating layer 70

[0057] Second insulating layer 80

[0058] Substrate layer 231

[0059] First coating 232

[0060] Gap G1, G2, G3

[0061] First inorganic particle layer 232a

[0062] First adhesive layer 232b

[0063] Side 231a

[0064] Second coating 233

[0065] Second inorganic particle layer 233a

[0066] Second adhesive layer 233b

[0067] Part 23b

[0068] Part 3, 23c

[0069] Second separating membrane 24

[0070] Electrical equipment 1

[0071] First direction Z

[0072] Second direction Y

[0073] The third direction is X. Detailed Implementation

[0074] 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.

[0075] 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.

[0076] Additionally, for simplicity and clarity, the dimensions or thicknesses of various components and layers may be enlarged in the accompanying drawings. Throughout the text, the same values ​​refer to the same elements. 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 elements A and B may be indirectly connected to each other.

[0077] Furthermore, when describing the implementation of this application, the word "may" refers to "one or more implementations of this application".

[0078] 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 understood that the term "comprising," when 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. 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, the first element, component, region, layer, or portion discussed below may be referred to as the second element, component, region, layer, or portion without departing from the teachings of the exemplary embodiments.

[0079] In this application, "multiple" means two or more.

[0080] In this application, the electrochemical device includes any device in which an electrochemical reaction occurs, and specific examples include all types of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. For example, the electrochemical device is a lithium secondary battery, which may include lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, or lithium-ion polymer secondary batteries.

[0081] Please see Figure 1 One embodiment of this application provides an electrochemical device 100, including a housing 10 and an electrode assembly 20 housed in the housing 10. Figure 2 , Figure 3 (shown in the diagram) and electrolyte, first metal plate 30 and second metal plate 40. In some embodiments, the housing 10 is a metal housing, such as a steel or aluminum housing. In other embodiments, the housing 10 is a packaging bag obtained by encapsulating with an encapsulation film, that is, the electrochemical device 100 can be a pouch battery. Figure 2 and Figure 3 The electrochemical device 100 shown includes an electrode assembly 20. In other embodiments, the electrochemical device 100 includes multiple electrode assemblies 20 to achieve a high voltage output.

[0082] like Figure 4As shown, the electrode assembly 20 includes a plurality of electrodes and a first insulating film 23 disposed between the plurality of electrodes. The plurality of electrodes are stacked along a first direction Z to form a stacked structure. In this embodiment, the first direction Z refers to the thickness direction of the electrode assembly 20. The plurality of electrodes include first electrodes 21 and second electrodes 22 with opposite polarities. The first insulating film 23 is disposed between adjacent first electrodes 21 and second electrodes 22 to reduce the risk of short circuit due to direct contact between the first electrodes 21 and second electrodes 22.

[0083] The first metal plate 30 and the second metal plate 40 are electrically connected to the electrode assembly 20 and extend from the housing 10 to connect to external components (not shown). Specifically, the first electrode 21 includes a first current collector 211 and a first active material layer 212, the first active material layer 212 being disposed on at least one surface of the first current collector 211, and the first metal plate 30 being electrically connected to the first current collector 211. The second electrode 22 includes a second current collector 221 and a second active material layer 222, the second active material layer 222 being disposed on at least one surface of the second current collector 221, and the second metal plate 40 being electrically connected to the second current collector 221.

[0084] In some embodiments, the first electrode 21 is a positive electrode, and the second electrode 22 is a negative electrode. Specifically, the first current collector 211 includes at least one of Ni, Ti, Cu, Ag, Au, Pt, Fe, Al, and combinations thereof. The first active material layer 212 includes a positive electrode active material, which may include 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, lithium nickel cobalt aluminum oxide, and combinations thereof. The second current collector 221 includes at least one of Ni, Ti, Cu, Ag, Au, Pt, Fe, Al, and combinations thereof. The second active material layer 222 includes a negative electrode active material, which may be selected from at least one of graphite materials, alloy materials, lithium metal, and alloys thereof. Graphite 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.

[0085] Please see Figures 2 to 4The electrode assembly 20 further includes a first surface 201, a second surface 202, a second end face 203, a first end face 204, a first side face 205, and a second side face 206. The first surface 201 and the second surface 202 are opposite to each other in the first direction Z. In the first direction Z, the surfaces of the two outermost electrodes among the plurality of electrodes serve as the first surface 201 and the second surface 202, respectively. In some embodiments, the current collector surfaces of the two outermost electrodes among the plurality of electrodes serve as the first surface 201 and the second surface 202. The second end face 203 and the first end face 204 are opposite to each other in the second direction Y and are connected between the first surface 201 and the second surface 202. A first metal plate 30 and a second metal plate 40 extend from the second end face 203. The first metal plate 30 and the second metal plate 40 can extend directly out of the housing 10, or they can be connected to another metal plate that extends out of the housing 10. The first side face 205 and the second side face 206 are opposite to each other in the third direction X and are connected between the first surface 201 and the second surface 202. In this application, the third direction X refers to the width direction of the electrode assembly 20, and the second direction Y refers to the length direction of the electrode assembly 20. The second direction Y is also the direction in which the first metal plate 30 and the second metal plate 40 extend, and the first direction Z, the third direction X, and the second direction Y are perpendicular to each other.

[0086] The first separator 23 includes at least one first portion 23a disposed among a plurality of electrodes. In some embodiments, the first separator 23 includes a plurality of first portions 23a, each first portion 23a being used to separate adjacent first electrodes 21 and second electrodes 22. The plurality of first portions 23a are separately disposed, that is, the plurality of first portions 23a are configured as independent separators. In this case, the electrode assembly 20 is obtained by alternately stacking first electrodes 21, first portions 23a and second electrodes 22. The edges of the first portions 23a of the first separator 23 extend beyond the edges of the electrodes in both the third direction X and the second direction Y, so as to separate adjacent first electrodes 21 and second electrodes 22. The end faces of the first portions 23a of the first separator 23 on both sides of the second direction Y are respectively used as second end faces 203 and first end faces 204, and the end faces of the first portions 23a of the first separator 23 on both sides of the third direction X are respectively used as first side faces 205 and second side faces 206.

[0087] Please see Figure 2 , Figure 3 and Figure 5 The electrochemical device 100 also includes a first insulating layer 50. The first insulating layer 50 is generally sheet-like, covering at least a portion of the first surface 201, at least a portion of the second surface 202 and at least a portion of the first end face 204, and is bonded to the first surface 201, the second surface 202 and the first end face 204. Figure 5In this configuration, the first insulating layer 50 is connected to the surface of the current collector of the two electrodes serving as the first surface 201 and the second surface 202. The first insulating layer 50 binds the electrode assembly 20 in the first direction Z and the second direction Y, reducing the risk of short circuits caused by the contraction of the first portion 23a of the first insulating film 23 near the first end face 204 in the second direction Y during thermal and mechanical abuse. It also reduces the stress on the first end face 204 during drops, thus reducing the risk of electrode damage.

[0088] Please see Figure 2 and Figure 3 The width of the electrode assembly 20 in the third direction X is defined as W1, and the width of the first insulating layer 50 in the third direction X is defined as W2, where 0.7W1≤W2≤W1. When W2<0.7W1, the width of the first insulating layer 50 is small, and the connection area between the first insulating layer 50 and the first end face 204 is small, that is, the connection area between the first insulating layer 50 and the first insulating membrane 23 is small. Therefore, the first insulating membrane 23 is prone to shrinkage during hot box and drop processes, leading to internal short circuits. In some embodiments, W2≤0.95W1 is used to balance the tolerance of the first insulating layer 50 during the manufacturing process and improve the electrolyte wetting effect of the first end face 204.

[0089] Please see Figures 2 to 4 In some embodiments, the electrochemical device 100 further includes a fourth insulating layer 60 and a third insulating layer 70. The fourth insulating layer 60 is generally sheet-like and covers at least a portion of the first surface 201, at least a portion of the second surface 202, and at least a portion of the first side surface 205, and is connected to all three surfaces. The fourth insulating layer 60 binds the electrode assembly 20 in the first direction Z and the third direction X, reducing the risk of the first portion 23a of the first separator 23 contracting in the third direction X near the first side surface 205. The third insulating layer 70 is generally sheet-like and covers at least a portion of the first surface 201, at least a portion of the second surface 202, and at least a portion of the second side surface 206, and is connected to all three surfaces. The third insulating layer 70 binds the electrode assembly 20 in the first direction Z and the third direction X, reducing the risk of the first portion 23a of the first separator 23 contracting in the third direction X near the second side surface 206.

[0090] Please see Figure 2 , Figure 3 and Figure 5In some embodiments, the electrochemical device 100 further includes a second insulating layer 80. The second insulating layer 80 is generally sheet-like, covering at least a portion of the first surface 201, at least a portion of the second surface 202, and a portion of the second end face 203, and is connected to both the first surface 201, the second surface 202, and the second end face 203. The second insulating layer 80 binds the electrode assembly 20 in the first direction Z and the second direction Y, reducing the risk of the first portion 23a of the first insulating membrane 23 contracting in the second direction Y near the second end face 203. In this embodiment, the electrochemical device 100 includes three second insulating layers 80. One second insulating layer 80 is disposed between the first metal plate 30 and the second metal plate 40, one second insulating layer 80 is disposed between the first metal plate 30 and the first side surface 205, and one second insulating layer 80 is disposed between the second metal plate 40 and the second side surface 206. This increases the connection area between the second insulating layer 80 and the second end face 203, maintains the adhesion between the second insulating layer 80 and the second end face 203, and further reduces the risk of shrinkage of the first portion 23a of the first separating membrane 23 near the second end face 203.

[0091] In some embodiments, the first insulating layer 50, the fourth insulating layer 60, the third insulating layer 70, and the second insulating layer 80 are all adhesive and are bonded to the electrode assembly 20. The materials of the first insulating layer 50, the fourth insulating layer 60, the third insulating layer 70, and the second insulating layer 80 can all be single-sided or double-sided adhesive.

[0092] Please see Figure 6 The first separator 23 has a laminated film structure. Specifically, the first separator includes a substrate layer 231 and a plurality of first coatings 232 spaced apart on one surface of the substrate layer 231. The first coatings 232 bond to the first electrode 21. In another embodiment, the first coatings 232 may also bond to the second electrode 22. A gap G1 is provided between two adjacent first coatings 232. The gap G1 between the plurality of first coatings 232 provides space for electrolyte transport. After electrolyte injection, the electrolyte can flow through the gap G1 and fully wet the electrode. In this case, even if the first insulating layer 50 is provided to bind the electrode assembly 20 in the first direction Z and the second direction Y, the electrolyte can still wet the electrode through the gap G1.

[0093] In one embodiment, the first coating 232 includes a first inorganic particle layer 232a and a first adhesive layer 232b stacked together. The first inorganic particle layer 232a is in contact with the substrate layer 231, and the first adhesive layer 232b is disposed on the surface of the first inorganic particle layer 232a facing away from the substrate layer 231. The first separator 23 is bonded to the adjacent electrode through the first adhesive layer 232b. The first adhesive layer 232b can bond the electrode, improve the interfacial adhesion between the first separator 23 and the electrode, reduce the expansion deformation during gas generation inside the electrochemical device 100, that is, improve the deformation resistance of the electrochemical device 100, reduce the risk of deformation and structural damage of the electrode assembly 20, thereby improving the cycle performance of the electrochemical device 100.

[0094] Please see Figure 7 The first coating 232 is disposed in strip form on the surface of the substrate layer 231, and multiple first coatings 232 are arranged parallel to each other. The substrate layer 231 includes two opposite sides 231a in the second direction Y. The angle between the first coating 232 and the side 231a is θ1. The first coating 232 is inclined relative to the side 231a, i.e., 0° < θ1 < 90°. Therefore, the adhesion between the first coating 232 and the electrode is continuously distributed on the edges of the electrode assembly in the second direction Y and the third direction X, improving the electrode assembly's resistance to deformation and improving cycle performance. In some embodiments, 25° ≤ θ1 ≤ 65° to maintain the adhesion between the first coating 232 and the electrode edge, suppressing edge deformation of the electrode, thereby improving cycle performance. When θ1 < 25°, since the first coating 232 is relatively flush with the third direction X, the adhesion between the first separator 23 and the electrode in the second direction Y may be reduced, which may cause deformation of the edge of the electrode assembly 20 in the third direction X, affecting cycle life. When θ1 > 65°, since the first coating 232 is relatively flush with the second direction Y, the adhesion between the first separator 23 and the electrode in the third direction X may be reduced, which may cause the edge of the electrode assembly 20 in the second direction Y to deform and affect the cycle life.

[0095] like Figure 7 As shown, in some embodiments, viewed along the first direction Z, the width of the first coating 232 is D1, and the distance between two adjacent first coatings 232 is D2, where D1 and D2 satisfy: 0.3D2≤D1≤0.5D2. When D1>0.5D2, with a fixed electrode area, D2 is relatively small, reducing the space available for electrolyte transport. Poor electrolyte wetting leads to lithium plating on the electrode, affecting cycle performance. When D1<0.3D2, the bonding area between the first coating 232 and the electrode decreases, reducing adhesion and deformation resistance, thus affecting cycle performance.

[0096] like Figure 6As shown, in some embodiments, the first separator 23 further includes a plurality of second coatings 233 spaced apart on one surface of the substrate layer 231, with the substrate layer 231 located between the first coating 232 and the second coatings 233. When the first coating 232 bonds the first electrode 21, the second coating 233 bonds the second electrode 22. A gap G2 is also present between adjacent second coatings 233, serving as a channel for electrolyte transport. Therefore, the provision of the second coatings 233 further improves the electrolyte wetting effect, further reduces the problem of lithium plating on the electrode caused by poor electrolyte wetting, thereby improving cycle performance.

[0097] The second coating 233 includes a second inorganic particle layer 233a and a second adhesive layer 233b stacked together. The second inorganic particle layer 233a is in contact with the substrate layer 231, and the second adhesive layer 233b is disposed on the surface of the second inorganic particle layer 233a facing away from the substrate layer 231.

[0098] In some embodiments, the substrate layer 231 comprises a polymer film, a multilayer polymer film, or a nonwoven fabric formed from any one or a mixture of two or more of the following polymers: polyolefin, polyvinylidene fluoride, polyethylene terephthalate, cellulose, polyimide, polyamide, spandex, and polyphthalamide. Such polymers exhibit high thermal stability and are easily surface-treated, thereby facilitating the coating of the first coating 232 and the second coating 233 onto the substrate layer 231. Furthermore, these polymers possess good toughness and are easily bent.

[0099] Both the first inorganic particle layer 232a and the second inorganic particle layer 233a comprise inorganic particulate material, which includes at least one of boehmite, aluminum hydroxide, or magnesium hydroxide particles. The first inorganic particle layer 232a and the second inorganic particle layer 233a may also include a binder that bonds the inorganic particulate material together. The binder may include polyvinylidene fluoride or a copolymer of vinylidene fluoride and hexafluoropropylene.

[0100] Both the first adhesive layer 232b and the second adhesive layer 233b include an adhesive material, which includes at least one of the following polymers: a copolymer of vinylidene fluoride and hexafluoropropylene, a copolymer of vinylidene fluoride and trichloroethylene, polymethyl methacrylate, polyacrylic acid, polyacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, a copolymer of ethylene and vinyl acetate, polyimide, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl amylopectin, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, amylopectin, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, a copolymer of acrylonitrile, styrene, and butadiene, polyvinyl alcohol, polyvinyl ether, polytetrafluoroethylene, polyhexafluoropropylene, a copolymer of styrene and butadiene, or polyvinylidene fluoride. These polymers can produce a strong adhesive effect, bonding the first separator 23 and the first electrode 21 or the second electrode 22 together.

[0101] Please refer to the following: Figure 8 In some embodiments, the second coating 233 is arranged in a strip shape, and multiple second coatings 233 are arranged parallel to each other. The angle between the second coating 233 and the side 231a is θ2. The second coating 233 is inclined relative to the side 231a, i.e., 0° < θ2 < 90°. In some embodiments, 25° ≤ θ2 ≤ 65° to maintain the adhesion between the second coating 233 and the edge of the electrode, further suppressing edge deformation of the electrode, thereby improving cycle performance. When θ2 < 25°, since the second coating 233 is relatively flush with the third direction X, the adhesion between the first separator 23 and the electrode in the second direction Y may be reduced, which may cause the edge of the electrode assembly 20 in the third direction X to deform, affecting cycle life. When θ2 > 65°, since the second coating 233 is relatively flush with the second direction Y, the adhesion between the first separator 23 and the electrode in the third direction X may be reduced, which may cause the edge of the electrode assembly 20 in the second direction Y to deform, affecting cycle life.

[0102] like Figure 8 As shown, the first coating 232 and the second coating 233 intersect on opposite planes, and the included angle between the first coating 232 and the second coating 233 is θ3, where 0° < θ3 < 180°. The gaps G1 between the multiple first coatings 232 and the gaps G2 between the multiple second coatings 233 are staggered to further improve the electrolyte wetting effect. Figure 9 As shown, in another embodiment, the first coating 232 and the second coating 233 can also be arranged in parallel, in which case the angle θ1 between the first coating 232 and the side 231a is equal to the angle θ2 between the second coating 233 and the side 231a.

[0103] Please see Figure 9Each first coating 232 or each second coating 233 can be discontinuously arranged, such as being arranged in multiple block-like or island-like shapes on the surface of the substrate layer 231. In this case, the angle θ1 between the first coating 232 and the side 231a is the angle between the line connecting the multiple block-like or island-like portions and the side 231a, and the angle θ2 between the second coating 233 and the side 231a is the angle between the line connecting the multiple block-like or island-like portions and the side 231a. Each discontinuously arranged first coating 232 or each discontinuously arranged second coating 233 also has a gap G3, which can serve as a channel for electrolyte transport, further improving electrolyte transport performance.

[0104] Please see Figure 10 In another embodiment, the plurality of first portions 23a of the first isolation membrane 23 are configured as a single unit, i.e., the first isolation membrane 23 is integrally formed. The first isolation membrane 23 has a Z-shaped fold structure. Specifically, in the first direction Z, the first isolation membrane 23 is bent in a Z-shape to form a Z-shaped fold structure. The first isolation membrane 23 with the Z-shaped fold structure includes only two ends, reducing the risk of internal short circuits caused by the contraction of the first isolation membrane 23, thereby improving safety performance.

[0105] Please see Figure 11 In another embodiment, the first separator 23 further includes a second portion 23b and a third portion 23c located outside the plurality of electrodes and opposite to each other in the first direction Z. The surface of the second portion 23b facing away from the electrodes serves as the first surface 201 of the electrode assembly 20 and is connected to the first insulating layer. The surface of the third portion 23c facing away from the electrodes serves as the second surface 202 of the electrode assembly 20 and is connected to the first insulating layer. The plurality of first portions 23a, second portions 23b, and third portions 23c of the first separator 23 are configured integrally to form a wound structure, in which the plurality of electrodes are located. Specifically, the first separator 23 is wound around one end of the first separator 23 in the second direction Y, sequentially winding n electrodes to form a wound structure, where n is an integer greater than or equal to 1. That is, n electrodes are provided between every two adjacent first portions 23a. Figure 11 The diagram shows three electrodes between two adjacent first portions 23a. When n is greater than or equal to 2, a second separator 24 is also provided between the electrodes between two adjacent first portions 23a. The second separator 24 is made of an insulating material and is used to prevent the electrodes between two adjacent first portions 23a from directly contacting each other and short-circuiting. The material of the second separator 24 may include at least one of polyolefin, polyvinylidene fluoride, polyethylene terephthalate, cellulose, polyimide, polyamide, spandex, or polyphthalamide.

[0106] The first separator 23, integrally formed, is configured as a wound structure. The first separator 23 as a whole binds multiple electrodes in the first direction Z and the third direction X, eliminating the need for additional second and third insulating layers to bind the electrode assembly 20 in the first direction Z and the third direction X. Compared to the case where the second and third insulating layers of the electrode assembly 20 are configured to bind in the first direction Z and the third direction X, the wound structure of the first separator 23 provides weaker binding to the edges of the electrodes in the third direction X, facilitating electrolyte flow through the edges of the electrodes in the third direction X and ensuring thorough wetting of the electrodes. Furthermore, the first separator 23 includes a second portion 23b and a third portion 23c located outside the multiple electrodes. The first insulating layer 50 is connected to the second portion 23b and the third portion 23c of the first separator 23. The surface roughness of the first separator 23 is greater than the surface roughness of the current collector of the electrodes, increasing the adhesion between the first insulating layer 50 and the electrode assembly 20 and reducing the risk of the first insulating layer 50 detaching.

[0107] Please see Figure 12 One embodiment of this application also provides an electrical device 1, which includes the electrochemical device 100 as described above. The electrical 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 source, a motor, a car, a motorcycle, an electric bicycle, a bicycle, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and lithium-ion capacitors, etc.

[0108] The present application will be described in detail below through specific embodiments and comparative examples. In particular, an electrochemical device using a pouch cell is used as an example, and the specific preparation process and testing methods are described in conjunction with the illustration. 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.

[0109] Example 1

[0110] A slurry formed by mixing inorganic particulate material and binder is applied intermittently to the surface of a substrate layer to form multiple spaced-apart first inorganic particulate layers. Then, an adhesive is applied to the surfaces of these first inorganic particulate layers to form multiple first adhesive layers, resulting in multiple spaced-apart first coatings. Next, a slurry formed by mixing inorganic particulate material and binder is applied intermittently to the other surface of the substrate layer to form multiple spaced-apart second inorganic particulate layers. Finally, an adhesive is applied to the surfaces of these second inorganic particulate layers to form multiple second adhesive layers, resulting in multiple spaced-apart second coatings, thus obtaining a first release film. The relationship between the width D1 of the first coating and the distance D2 between two adjacent first coatings is D1 = 0.3D2, and the angle θ1 between the first coating and the side edge of the substrate layer is 45°.

[0111] An electrode assembly is obtained by stacking a first separator and multiple electrodes. The first separator has a wound structure, and three electrodes are disposed between the first portions of two adjacent first separators. The surfaces of the second and third portions of the first separator facing away from the electrodes serve as the first and second surfaces of the electrode assembly. A first insulating layer is bonded to the first surface, second surface, and second end face of the electrode assembly. The relationship between the width W2 of the first insulating layer and the width W1 of the electrode assembly is: W2 = 0.8W1.

[0112] Electrode components and electrolyte are encapsulated in an aluminum-plastic film to obtain an electrochemical device.

[0113] Example 2-13

[0114] The difference from Example 1 is that at least one of the values ​​of D1 / D2, W2 / W1, and the included angle θ1 is different.

[0115] Comparative Example 1

[0116] The difference from Example 1 is that the slurry is continuously coated on the surface of the substrate layer to form a first inorganic particle layer and a second inorganic particle layer, and the slurry is continuously coated on the surface of the first inorganic particle layer and the surface of the second inorganic particle layer to form a first adhesive layer. That is, the multiple first coatings and multiple second coatings that are spaced apart in Example 1 are respectively connected into one piece.

[0117] The electrochemical devices of Comparative Example 1 and Examples 1-10 and 12-13 were subjected to cyclic testing, and the test results are recorded in Table 1. The cyclic testing steps included: charging the electrochemical device to 4.43 V at a constant current of 1 C at 45 degrees Celsius, then charging it to 0.05 C at a constant voltage, letting it stand for 5 min, and then discharging it to 3.0 V at 0.7 C. The discharge capacity at this point was measured using a commercially available battery performance testing machine and was taken as the initial discharge capacity of the electrochemical device, which was counted as 100%. The above charge and discharge steps were repeated for 1000 cycles. The ratio of the discharge capacity of the electrochemical device after the cycle to the initial capacity multiplied by 100% was the capacity retention rate. The electrochemical device was fully charged according to the charging process, and then disassembled to observe the interface of the negative electrode and the lithium plating.

[0118] Table 1

[0119]

[0120] Comparing Comparative Example 1 with Examples 1-10 and 12-13, it can be seen that when a first insulating layer with a relatively wide width is used to bind the electrode assembly in the first direction, when the first and second coatings are continuously coated on the two surfaces of the substrate layer, severe electrolyte wetting occurs, resulting in a large amount of purple spot lithium deposition in the main area of ​​the electrode (the area near the center of the electrode), affecting the lifespan of the electrochemical device. However, when the first and second coatings are intermittently coated on the two surfaces of the substrate layer, the gaps between adjacent first and second coatings provide space for electrolyte transport, improving the electrolyte wetting effect and increasing the lifespan of the electrochemical device. Therefore, Comparative Example 1 has the lowest cycle capacity retention rate.

[0121] Comparing Examples 1-3 and 9-10, it can be seen that when 0.3D2≤D1≤0.5 is satisfied, the negative electrode interface is good after cycling, and the electrochemical device has a high capacity retention rate. When D1 is too small, the bonding area between the first separator and the electrode is too small, resulting in a decrease in the overall mechanical strength of the electrochemical device, which is prone to deformation during cycling, leading to poor interface. When D1 is too large, the reserved space for electrolyte transmission on the first separator is too small, resulting in poor wetting, which in turn causes poor interface.

[0122] Comparing Examples 2, 7, 8, and 12-13, it can be seen that when 25°≤θ1≤65° is satisfied, the negative electrode interface is good after cycling, and the electrochemical device has a high capacity retention rate; when θ1 is too small or too large, the edge of the electrode is easily deformed, resulting in poor interface.

[0123] Comparing Examples 2 and 4-6, it can be seen that when 0.7W1≤W2 is satisfied, the negative electrode interface is good after cycling, and the electrochemical device has a high capacity retention rate. Moreover, as W2 / W2 increases, the cycle capacity retention rate shows a trend of first increasing and then remaining unchanged. When W2≥0.85W1, the electrochemical device has an even higher capacity retention rate.

[0124] The electrochemical devices of Comparative Example 1 and Examples 2 and 14 were subjected to a hot chamber test, and the test results are recorded in Table 2. The hot chamber test procedure included: charging the electrochemical device to 4.43 V at a constant current of 0.2 C at 25±5℃, and then charging it to 0.01 C at a constant voltage. The electrochemical device was then heated to 140±2℃ at a rate of 5±2℃ / min and held for 60 min. The electrochemical device was observed for any failure phenomena such as fire or explosion. If no failures were observed, the hot chamber test was passed; otherwise, it failed. The pass rate of the hot chamber test for 20 electrochemical devices was calculated. After the test, the electrochemical device was disassembled to observe whether diaphragm shrinkage occurred.

[0125] Table 2

[0126]

[0127] Comparing Comparative Example 1 and Example 2, it can be seen that when the surfaces of the second and third parts of the first separator are used as the first and second surfaces of the electrode assembly, that is, when the electrode assembly is finished with the first separator, the first coating and the second coating are applied alternately to the two surfaces of the substrate layer, which improves the pass rate of the hot box test and reduces the shrinkage of the first separator.

[0128] Drop tests were conducted on the electrochemical devices of Examples 1-6, 9, and 11, and the test results are recorded in Table 3. The drop test procedure included: charging the electrochemical device to 4.43 V with a constant current of 0.2 C at 25±5℃, and then charging it to 0.01 C with a constant voltage. The electrochemical device was fixed in a drop test fixture and dropped 6 times sequentially from a height of 1.8 m along the 6 sides of the drop test fixture. After each drop, the electrochemical device was observed for damage, and the open-circuit voltage of the electrochemical device was measured. If the voltage was less than 3.0 V, the electrochemical device was considered to have failed. If no damage was found and the open-circuit voltage was higher than 3.0 V, it was considered not to have failed, and the test continued until failure. The number of drops performed when the electrochemical device failed was recorded. Subsequently, the electrochemical device was disassembled and analyzed to observe whether diaphragm shrinkage occurred.

[0129] Table 3

[0130]

[0131] Comparing Examples 1-3 and 9, it can be seen that when 0.3D2≤D1≤0.5D2 is satisfied, the electrochemical device has a higher drop resistance and better drop resistance. When D1 is too small, the bonding area between the first separator and the electrode is small, and the binding effect of the first separator on the entire electrode assembly is limited. The mutual impact between the electrodes and between the electrode assembly and the shell increases, which can easily lead to shell damage. Therefore, the electrochemical device in Example 9 has the worst drop resistance.

[0132] Comparing Examples 2, 4-6, and 11, it can be seen that when 0.7W1≤W2 is satisfied, the electrochemical device has a higher drop count and better drop resistance. In Example 11, W2 is too small, and failure occurs due to the shrinkage of the first separator during the drop process, resulting in the fewest drop counts and the worst drop resistance.

[0133] 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, characterized in that, include: case; An electrode assembly is housed in the housing. The electrode assembly includes a plurality of electrodes stacked along a first direction and a first insulating membrane disposed between the plurality of electrodes. The electrode assembly also includes a first surface and a second surface opposite to each other in the first direction and a first end face connected between the first surface and the second surface. The first insulating layer is bonded to the first surface, the second surface and the first end face; and The electrolyte is contained within the casing; The first separator includes a substrate layer and a first coating layer spaced apart on the surface of the substrate layer facing the adjacent electrode. The first coating is strip-shaped, and the substrate layer includes two opposite sides in a second direction perpendicular to the first direction. The first coating is inclined relative to the sides. When viewed along the first direction, the angle between the first coating and the sides is θ1, where 25°≤θ1≤65°.

2. The electrochemical device as described in claim 1, characterized in that, When viewed along the first direction, the width of the first coating is D1, the spacing between two adjacent first coatings is D2, and 0.3D2≤D1≤0.5D2.

3. The electrochemical device as described in claim 1, characterized in that, The first isolation membrane further includes a plurality of second coatings, which are spaced apart on the surface of the substrate layer opposite to the plurality of first coatings.

4. The electrochemical device as described in claim 3, characterized in that, The first coating and the second coating are intersecting at opposite planes.

5. The electrochemical device as described in claim 1, characterized in that, The first separator includes a plurality of first portions located among the plurality of electrodes and second and third portions located outside the plurality of electrodes and opposite to each other in the first direction. Each first portion is disposed between two adjacent electrodes, and the plurality of first portions, second portions and third portions are configured integrally to form a wound structure.

6. The electrochemical device as claimed in claim 1, characterized in that, In a third direction perpendicular to the first direction, the width of the electrode assembly is W1, the width of the first insulating layer is W2, and 0.7W1≤W2≤W1.

7. The electrochemical device as described in claim 6, characterized in that, 0.7W1≤W2≤0.95W1.

8. The electrochemical device as described in claim 7, characterized in that, 0.85W1≤W2≤0.95W1.

9. The electrochemical device as claimed in claim 1, characterized in that, The first coating includes a first inorganic particle layer and a first adhesive layer. The first inorganic particle layer is in contact with the substrate layer, and the adhesive layer is disposed on the surface of the inorganic particle layer opposite to the substrate layer and is bonded to the adjacent electrode.

10. The electrochemical device as claimed in claim 1, characterized in that, The first coating comprises inorganic particles and a binder.

11. The electrochemical device as claimed in claim 1, characterized in that, The electrochemical device further includes a second insulating layer, and the electrode assembly further includes a second end face connected between the first surface and the second surface. The length direction of the electrode assembly is defined as the second direction. The first surface and the second surface are opposite to each other in the second direction. The second insulating layer is connected to the first surface, the second surface and the second end face.

12. The electrochemical device as claimed in claim 11, characterized in that, The first insulating layer is a single-sided or double-sided adhesive, and / or the second insulating layer is a single-sided or double-sided adhesive.

13. The electrochemical device as claimed in claim 1, characterized in that, The electrochemical device further includes a first metal plate and a second metal plate, both of which are connected to the electrode assembly; in a third direction perpendicular to the first direction, the electrode assembly also includes a second end face opposite to the first end face, and the first metal plate and the second metal plate extend out of the electrode assembly from the second end face.

14. The electrochemical device as claimed in claim 1, characterized in that, The casing is a packaging bag.

15. An electrical appliance, characterized in that, Includes the electrochemical device as described in any one of claims 1 to 14.

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