Electrochemical apparatus and electric device including same

Abstract

An electrochemical apparatus and an electric device including same. The electrochemical apparatus comprises a housing, an electrode assembly, a first insulating layer and an electrolytic solution, wherein the electrode assembly and the electrolytic solution are accommodated in the housing. The electrode assembly comprises a plurality of electrode sheets stacked in a first direction, and a first separator arranged between the plurality of the electrode sheets. The electrode assembly further comprises a first surface and a second surface which are opposite each other in the first direction, and a first end surface connected between the first surface and the second surface. The first insulating layer is bonded to all of the first surface, the second surface and the first end surface. The first separator comprises a base material layer, and first coatings that are spaced apart from the surface of the base material layer facing an adjacent electrode sheet.

Description

Electrochemical device and electrical equipment containing the same Technical Field

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

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

[0003] Summary of the Invention

[0004] One object of the present application is to provide a battery having good cycle performance and reducing the risk of internal short circuit in electrochemical devices.

[0005] The present application provides an electrochemical device comprising 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 comprises a plurality of electrode sheets stacked along a first direction and a first isolation membrane disposed between the plurality of electrode sheets. The electrode assembly further comprises a first surface and a second surface opposing 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. The first isolation membrane comprises a substrate layer and a first coating layer spaced apart on surfaces of the substrate layer facing adjacent electrode sheets.

[0006] The present application sets a first insulating layer connecting the first surface, the second surface and the first end face of the electrode assembly. The first insulating layer constrains the electrode assembly in the first direction, reduces the risk of internal short circuit caused by the shrinkage of the first isolation membrane, and improves safety performance. However, the use of the first insulating layer to constrain the electrode assembly in the first direction may reduce the gap between the first isolation membrane and the adjacent electrode, thereby reducing the space available for electrolyte transmission and causing poor electrolyte infiltration. The present application sets the first isolation membrane to include a plurality of first coatings arranged at intervals. The gap between two adjacent first coatings reserves space for electrolyte transmission, improves the electrolyte infiltration effect, improves the problem of lithium plating on the electrode caused by poor electrolyte infiltration, and improves the cycle performance. Therefore, the electrochemical device of the present application has high cyclability while maintaining safety.

[0007] In some possible implementations, the first coating layer is strip-shaped, the substrate layer includes two opposing sides in a second direction perpendicular to the first direction, and the multiple first coating layers are arranged obliquely relative to the sides. Consequently, the adhesion between the first coating layer and adjacent electrode sheets is continuously distributed along all edges of the electrode assembly, enhancing the electrode assembly's resistance to deformation and improving cycling performance.

[0008] In some possible implementations, when viewed along the first direction, the angle θ1 between the first coating and the side edge is 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, preventing edge deformation of the electrode, thereby improving cycle performance.

[0009] In some possible implementations, when viewed along a first direction, the width of the first coating layer is D1, the spacing between two adjacent first coating layers is D2, and 0.3D2≤D1≤0.5D2. When D1>0.5D2, given a given electrode area, D2 is small, reducing the space available for electrolyte transmission. Poor electrolyte wetting exacerbates the lithium deposition problem in the electrode, affecting cycle performance. When D1<0.3D2, the bonding area between the first coating layer and the electrode is reduced, the bonding force is reduced, and the deformation resistance is correspondingly reduced, affecting cycle performance.

[0010] In some possible implementations, the first separator further includes multiple second coating layers, which are spaced apart on a surface of the substrate layer facing away from the multiple first coating layers. The gaps between adjacent second coating layers provide space for electrolyte transfer, improving electrolyte wetting, further alleviating lithium deposition in the electrode caused by poor electrolyte wetting, and enhancing cycle performance.

[0011] In some possible implementations, the first coating and the second coating intersect at different surfaces, so that the gaps between two adjacent first coatings and the gaps between two adjacent second coatings are staggered, further improving the electrolyte infiltration effect, further improving the problem of lithium plating on the electrode caused by poor electrolyte infiltration, and improving the cycle performance.

[0012] In some possible implementations, the first isolation membrane also includes a plurality of first portions located in the plurality of pole pieces and a second portion and a third portion located outside the plurality of pole pieces and opposite to each other in a first direction, each first portion being disposed between two adjacent pole pieces, and the plurality of first portions, second portions, and third portions being configured as a whole and forming a winding structure. The first isolation membrane is configured as a winding structure, which restrains the plurality of pole pieces in a plurality of different directions, without the need for configuring an additional insulating layer to restrain the plurality of pole pieces in a specific direction. Furthermore, the first insulating layer is connected to the second portion and the third portion of the first isolation membrane, thereby increasing the bonding force between the first insulating layer and the electrode assembly, reducing the risk of the first insulating layer falling off, and thereby reducing the risk of internal short circuit caused by shrinkage of the first isolation membrane.

[0013] In some possible implementations, in a third direction perpendicular to both the first and second directions, the electrode assembly has a width of W1, the first insulating layer has a width of W2, and 0.7W1≤W2≤W1. When the electrode assembly width W1 and the first insulating layer width W2 are within this range, the adhesion between the first insulating layer and the first end surface can be maintained, reducing the risk of internal short circuits caused by shrinkage of the first separator and improving safety.

[0014] In some possible implementations, 0.7W1≤W2≤0.95W1. In some possible implementations, 0.85W1≤W2≤0.95W1.

[0015] In some possible implementations, the first coating layer 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 a surface of the inorganic particle layer facing away from the substrate layer and is bonded to the adjacent electrode. The first adhesive layer is bonded to the electrode to improve the interfacial adhesion between the first separator and the electrode, reduce expansion and deformation during gas generation within the electrochemical device, and improve cycle performance.

[0016] In some possible implementations, the first coating layer includes inorganic particles and a binder.

[0017] In some possible implementations, the electrochemical device further includes a second insulating layer, and the electrode assembly further includes a second end surface 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 each other in the second direction, and the second insulating layer is connected to the first surface, the second surface, and the second end surface. Providing the second insulating layer connecting the first surface, the second surface, and the second end surface of the electrode assembly reduces the risk of internal short circuiting caused by shrinkage of the end of the first separator near the second end surface.

[0018] In some possible implementations, the first insulating layer is single-sided tape or double-sided tape.

[0019] In some possible implementations, the second insulating layer is single-sided tape or double-sided tape.

[0020] 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 from the second end face of the electrode assembly.

[0021] In some possible implementations, the shell is a packaging bag.

[0022] The present application also provides an electrical device comprising any of the above-mentioned electrochemical devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0024] FIG1 is a first-direction view of an electrochemical device provided by one embodiment of the present application;

[0025] FIG2 is a first-direction view of the electrode assembly of the electrochemical device shown in FIG1 as viewed from the side where the first surface is located;

[0026] FIG3 is a first direction view of the electrode assembly shown in FIG2 as viewed from the side where the second surface is located;

[0027] FIG4 is a second direction view of the electrode assembly shown in FIG2;

[0028] FIG5 is a cross-sectional view of the electrode assembly shown in FIG2 along line VV;

[0029] FIG6 is a cross-sectional view of the electrode assembly shown in FIG4 along line VI-VI;

[0030] FIG7 is a first direction view of the first isolation film of the electrode assembly shown in FIG6 from a side close to the first surface of the electrode assembly;

[0031] FIG8 is a first direction view of the first isolation film shown in FIG7 from the side close to the second surface of the electrode assembly;

[0032] FIG9 is a first direction view of a first isolation film provided by another embodiment of the present application;

[0033] FIG10 is a second direction view of an electrode assembly provided by another embodiment of the present application;

[0034] FIG11 is a second direction view of an electrode assembly provided by another embodiment of the present application;

[0035] FIG12 is a schematic structural diagram of an electrical device provided in an embodiment of the present application.

[0036] Explanation of Main Component Symbols Electrochemical Device 100 Housing 10 Electrode Assembly 20 First Metal Plate 30 Second Metal Plate 40 First Separator 23 First Pole Sheet 21 Second Pole Sheet 22 First Current Collector 211 First Active Material Layer 212 Second Current Collector 221 Second Active Material Layer 222 First Surface 201 Second Surface 202 Second End Surface 203 First End Surface 204 First Side Surface 205 Second Side Surface 206 First Insulating Layer 50 Fourth Insulating Layer 60 Third Insulating Layer 70 Second Insulating Layer 80 Base Layer 231 First Coating Layer 232 Gaps G1, G2, G3 First Inorganic Particle Layer 232a First Adhesive Layer 232b Side 231a Second Coating Layer 233 Second Inorganic Particle Layer 233a Second Adhesive Layer 233b Second Portion 23b Third Portion 23c Second Separator24 Electrical equipment 1 First direction Z Second direction Y Third direction X DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application are described clearly and in detail below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present application. The terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0038] Below, embodiments of the present application will be described in detail. However, the present application may be embodied in many different forms and should not be construed as limited to the exemplary embodiments illustrated herein. Rather, these exemplary embodiments are provided to make the present application thorough and detailed for those skilled in the art.

[0039] In addition, for the sake of brevity and clarity, the size or thickness of various components, layers may be exaggerated in the accompanying drawings. Throughout the text, the same numerical value refers to the same element. In addition, it should be understood that when element A is referred to as being "connected to" 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.

[0040] Further, when describing embodiments of the present application, the use of “may” refers to “one or more embodiments of the present application.”

[0041] The professional terms used herein are for the purpose of describing specific embodiments and are not intended to limit the application. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. It should be understood that the term "comprising", when used in this specification, refers to the presence of narrated features, numerical values, steps, operations, elements and / or components, but does not exclude the presence or increase of one or more other features, numerical values, steps, operations, elements, components and / or combinations thereof. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts herein, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are used to distinguish an element, component, region, layer or part from another element, component, region, layer or part. Therefore, the first element, component, region, layer or part discussed below can be referred to as the second element, component, region, layer or part, without departing from the teaching of exemplary embodiments.

[0042] The term "plurality" in this application refers to two or more.

[0043] In this application, an electrochemical device includes any device that undergoes an electrochemical reaction, and specific examples thereof include all types of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. Exemplarily, the electrochemical device is a lithium secondary battery, which may include a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.

[0044] Referring to Figure 1, one embodiment of the present application provides an electrochemical device 100, comprising a housing 10, an electrode assembly 20 (shown in Figures 2 and 3) housed in the housing 10, an electrolyte, a first metal plate 30, and a second metal plate 40. In some embodiments, the housing 10 is a metal housing, such as a steel shell or an aluminum shell. In other embodiments, the housing 10 is a packaging bag obtained by packaging with a packaging film, that is, the electrochemical device 100 can be a soft-pack battery. Figures 2 and 3 show that the electrochemical device 100 includes one electrode assembly 20. In other embodiments, in order to achieve high voltage output, the electrochemical device 100 includes multiple electrode assemblies 20.

[0045] As shown in Figure 4, the electrode assembly 20 includes a plurality of electrode sheets and a first isolation film 23 disposed between the plurality of electrode sheets. The plurality of electrode sheets are stacked along a first direction Z to form a laminate structure. In this embodiment, the first direction Z refers to the thickness direction of the electrode assembly 20. The plurality of electrode sheets include a first electrode sheet 21 and a second electrode sheet 22 of opposite polarity. The first isolation film 23 is disposed between adjacent first electrode sheets 21 and second electrode sheets 22 to reduce the risk of a short circuit due to direct contact between the first electrode sheet 21 and the second electrode sheet 22.

[0046] The first metal plate 30 and the second metal plate 40 are each electrically connected to the electrode assembly 20 and extend from the housing 10 to connect to external components (not shown). Specifically, the first electrode sheet 21 includes a first current collector 211 and a first active material layer 212. The first active material layer 212 is disposed on at least one surface of the first current collector 211, and the first metal plate 30 is electrically connected to the first current collector 211. The second electrode sheet 22 includes a second current collector 221 and a second active material layer 222. The second active material layer 222 is disposed on at least one surface of the second current collector 221, and the second metal plate 40 is electrically connected to the second current collector 221.

[0047] In some embodiments, the first electrode sheet 21 is a positive electrode sheet, and the second electrode sheet 22 is a negative electrode sheet. 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 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.

[0048] Referring to Figures 2 to 4 , the electrode assembly 20 further includes a first surface 201, a second surface 202, a second end surface 203, a first end surface 204, a first side surface 205, and a second side surface 206. The first surface 201 and the second surface 202 are opposed in a first direction Z. In the first direction Z, the surfaces of the two outermost electrode sheets among the plurality of electrode sheets serve as the first surface 201 and the second surface 202, respectively. In some embodiments, the surfaces of the current collectors of the two outermost electrode sheets among the plurality of electrode sheets serve as the first surface 201 and the second surface 202. The second end surface 203 and the first end surface 204 are opposed in a second direction Y and connected between the first surface 201 and the second surface 202. The first metal plate 30 and the second metal plate 40 extend from the second end surface 203. The first metal plate 30 and the second metal plate 40 may extend directly from the housing 10 or may be connected to another metal plate that extends from the housing 10. The first side surface 205 and the second side surface 206 are opposed in a third direction X and connected between the first surface 201 and the second surface 202. In the present 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, wherein 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.

[0049] The first separator 23 includes at least one first portion 23a disposed between the plurality of electrode sheets. In some embodiments, the first separator 23 includes multiple first portions 23a, each of which is used to separate adjacent first and second electrode sheets 21, 22. The multiple first portions 23a are separately disposed, i.e., the multiple first portions 23a are configured as independent separators. In this case, the electrode assembly 20 is formed by alternatingly stacking the first electrode sheet 21, the first portion 23a, and the second electrode sheet 22. The edges of the first portion 23a of the first separator 23 extend beyond the edges of the electrode sheets in both the third direction X and the second direction Y, thereby separating the adjacent first and second electrode sheets 21, 22. The end surfaces of the first portion 23a of the first separator 23 on either side of the second direction Y serve as the second end surface 203 and the first end surface 204, respectively. The end surfaces of the first portion 23a of the first separator 23 on either side of the third direction X serve as the first side surface 205 and the second side surface 206, respectively.

[0050] Referring to Figures 2, 3, and 5, the electrochemical device 100 further includes a first insulating layer 50. The first insulating layer 50 is generally sheet-shaped 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 end surface 204. It is bonded to the first surface 201, the second surface 202, and the first end surface 204. In Figure 5, the first insulating layer 50 is connected to the surfaces of the current collectors of the two electrode sheets, the first surface 201 and the second surface 202. The first insulating layer 50 constrains 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 separator 23 near the first end surface 204 shrinking in the second direction Y during thermal and mechanical abuse, resulting in short circuiting between the first electrode sheet 21 and the second electrode sheet 22. It also reduces stress on the first end surface 204 during a drop, reducing the risk of damage to the electrode sheets.

[0051] Referring to Figures 2 and 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 isolation film 23 is small. Therefore, during the hot box and drop process, the first isolation film 23 is prone to shrinkage, resulting in an internal short circuit. In some embodiments, W2 ≤ 0.95W1 is used to balance the tolerance of setting the first insulating layer 50 during the manufacturing process and improve the electrolyte infiltration effect of the first end face 204.

[0052] Referring to 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-shaped 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 205, and is connected to the first surface 201, the second surface 202, and the first side 205. The fourth insulating layer 60 constrains the electrode assembly 20 in the first direction Z and the third direction X, reducing the risk of the end of the first portion 23a of the first separator 23 proximate to the first side 205 shrinking in the third direction X. The third insulating layer 70 is generally sheet-shaped 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 206, and is connected to the first surface 201, the second surface 202, and the second side 206. The third insulating layer 70 constrains the electrode assembly 20 in the first direction Z and the third direction X, reducing the risk of the end of the first portion 23a of the first separator 23 proximate to the second side 206 shrinking in the third direction X.

[0053] Referring to Figures 2, 3, and 5, in some embodiments, the electrochemical device 100 further includes a second insulating layer 80. The second insulating layer 80 is generally sheet-shaped and covers 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 surface 203. The second insulating layer 80 is connected to the first surface 201, the second surface 202, and the second end surface 203. The second insulating layer 80 constrains the electrode assembly 20 in the first direction Z and the second direction Y, reducing the risk of shrinkage in the second direction Y at the end of the first portion 23a of the first separator 23 proximal to the second end surface 203. In this embodiment, the electrochemical device 100 includes three second insulating layers 80, one of which is arranged between the first metal plate 30 and the second metal plate 40, one is arranged between the first metal plate 30 and the first side surface 205, and one is arranged 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 surface 203, maintains the adhesion between the second insulating layer 80 and the second end surface 203, and further reduces the risk of shrinkage of the first portion 23a of the first isolation membrane 23 close to the second end surface 203.

[0054] 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 adhere to the electrode assembly 20. The first insulating layer 50, the fourth insulating layer 60, the third insulating layer 70, and the second insulating layer 80 can be made of single-sided tape or double-sided tape.

[0055] Please refer to Figure 6. The first isolation membrane 23 has a laminated membrane structure. Specifically, the first isolation membrane includes a substrate layer 231 and a plurality of first coating layers 232 spaced apart on a surface of the substrate layer 231. The first coating layer 232 is bonded to the first electrode 21. In another embodiment, the first coating layer 232 may also be bonded to the second electrode 22. There is a gap G1 between two adjacent first coating layers 232. The gap G1 between the plurality of first coating layers 232 is a reserved space for electrolyte transmission. After injection, the electrolyte can flow through the gap G1 and fully infiltrate the electrode. In this case, even if the first insulating layer 50 is provided to constrain the electrode assembly 20 in the first direction Z and the second direction Y, the electrolyte can still infiltrate the electrode through the gap G1.

[0056] In one embodiment, the first coating layer 232 includes a first inorganic particle layer 232a and a first adhesive layer 232b that are stacked. 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 that faces away from the substrate layer 231. The first isolation film 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 isolation film 23 and the electrode, and reduce the expansion deformation during gas production within 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, and thus improve the cycle performance of the electrochemical device 100.

[0057] Referring to Figure 7 , a first coating layer 232 is disposed in a strip-like shape on the surface of the substrate layer 231 , with multiple first coating layers 232 arranged parallel to each other. The substrate layer 231 includes two side edges 231 a that oppose each other in the second direction Y. The angle between the first coating layer 232 and the side edges 231 a is θ1. The first coating layer 232 is inclined relative to the side edges 231 a, i.e., 0° < θ1 < 90°. This ensures that the adhesion between the first coating layer 232 and the electrode sheet is continuously distributed along the edges of the electrode assembly in the second direction Y and the third direction X, enhancing the electrode assembly's resistance to deformation and improving cycle performance. In some embodiments, the angle is 25° ≤ θ1 ≤ 65° to maintain adhesion between the first coating layer 232 and the electrode sheet edge, preventing deformation at the electrode sheet edge and thus improving cycle performance. When θ1 is less than 25°, since the first coating layer 232 is relatively flush with the third direction X, adhesion between the first separator 23 and the electrode sheet in the second direction Y may be reduced, potentially causing deformation at the electrode assembly 20 edge 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 isolation film 23 and the electrode sheet in the third direction X may be reduced, causing the edge of the electrode assembly 20 in the second direction Y to deform, affecting the cycle life.

[0058] As shown in FIG7 , in some embodiments, when viewed along the first direction Z, the width of the first coating layer 232 is D1, and the distance between two adjacent first coating layers 232 is D2, where D1 and D2 satisfy the following relationship: 0.3D2≤D1≤0.5D2. When D1>0.5D2, given a certain electrode area, D2 is smaller, which reduces the space available for electrolyte transmission. Poor electrolyte wetting causes lithium deposition in the electrode, affecting cycle performance. When D1<0.3D2, the bonding area between the first coating layer 232 and the electrode is reduced, the bonding force is reduced, and the deformation resistance is correspondingly reduced, affecting cycle performance.

[0059] As shown in FIG6 , in some embodiments, the first isolation film 23 further includes a plurality of second coating layers 233 spaced apart and disposed on a surface of the substrate layer 231 , with the substrate layer 231 located between the first coating layer 232 and the second coating layer 233 . When the first coating layer 232 adheres to the first electrode 21 , the second coating layer 233 adheres to the second electrode 22 . A gap G2 is also provided between two adjacent second coating layers 233 , serving as a channel for electrolyte transmission. Therefore, the provision of the second coating layer 233 further enhances the electrolyte wetting effect, further reducing the problem of lithium plating on the electrode caused by poor electrolyte wetting, thereby improving cycle performance.

[0060] The second coating layer 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 a surface of the second inorganic particle layer 233a that is away from the substrate layer 231 .

[0061] In some embodiments, substrate layer 231 comprises a polymer film, multilayer polymer film, or non-woven fabric formed from any one of the following polymers, or a mixture of two or more thereof: polyolefin, polyvinylidene fluoride, polyethylene terephthalate, cellulose, polyimide, polyamide, spandex, and polyphenylene phthalamide. These polymers have high thermal stability and are easily surface treated, making it easy to apply first coating 232 and second coating 233 to substrate layer 231. Furthermore, these polymers have good toughness and are easily bendable.

[0062] The first inorganic particle layer 232a and the second inorganic particle layer 233a each include an inorganic particle material, wherein the inorganic particle material 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 further include a binder to bond the inorganic particle materials together. The binder may include polyvinylidene fluoride or a copolymer of vinylidene fluoride and hexafluoropropylene.

[0063] The first adhesive layer 232b and the second adhesive layer 233b each 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, polyvinyl pyrrolidone, polyvinyl acetate, an ethylene-vinyl acetate copolymer, polyimide, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyvinyl alcohol, polyvinyl ether, polytetrafluoroethylene, polyhexafluoropropylene, a copolymer of styrene and butadiene, or polyvinylidene fluoride. These polymers can generate a strong adhesive effect to bond the first isolation membrane 23 to the first pole piece 21 or the second pole piece 22 together.

[0064] Referring also to FIG8 , in some embodiments, the second coating layer 233 is arranged in a strip shape, with multiple second coating layers 233 arranged parallel to each other. The angle between the second coating layer 233 and the side edge 231 a is θ2. The second coating layer 233 is inclined relative to the side edge 231 a, i.e., 0° < θ2 < 90°. In some embodiments, 25° ≤ θ2 ≤ 65° maintains adhesion between the second coating layer 233 and the electrode edge, further preventing edge deformation of the electrode, thereby improving cycle performance. When θ2 is less than 25°, since the second coating layer 233 is relatively flush with the third direction X, adhesion between the first separator 23 and the electrode in the second direction Y may be reduced, potentially causing deformation of the electrode assembly 20 edge in the third direction X, affecting cycle life. When θ2 is greater than 65°, since the second coating layer 233 is relatively flush with the second direction Y, adhesion between the first separator 23 and the electrode in the third direction X may be reduced, potentially causing deformation of the electrode assembly 20 edge in the second direction Y, affecting cycle life.

[0065] As shown in FIG8 , the first coating layer 232 and the second coating layer 233 intersect at different planes, and the angle between the first coating layer 232 and the second coating layer 233 is θ3, where 0°<θ3<180°. Thus, the gaps G1 between the multiple first coating layers 232 and the gaps G2 between the multiple second coating layers 233 are staggered, further improving the electrolyte infiltration effect. As shown in FIG9 , in another embodiment, the first coating layer 232 and the second coating layer 233 can also be arranged in parallel, in which case the angle θ1 between the first coating layer 232 and the side edge 231a is equal to the angle θ2 between the second coating layer 233 and the side edge 231a.

[0066] Referring to FIG. 9 , each first coating layer 232 or each second coating layer 233 may be intermittently disposed, such as in the form of multiple blocks or islands disposed on the surface of the substrate layer 231. In this case, the angle θ1 between the first coating layer 232 and the side edge 231a is the angle between the line connecting the multiple blocks or islands and the side edge 231a, and the angle θ2 between the second coating layer 233 and the side edge 231a is the angle between the line connecting the multiple blocks or islands and the side edge 231a. Each intermittent first coating layer 232 or each intermittent second coating layer 233 also has a gap G3, which can serve as a channel for electrolyte transmission, further improving electrolyte transmission performance.

[0067] Referring to Figure 10 , in another embodiment, the multiple first portions 23a of the first isolation film 23 are configured as a single unit, i.e., the first isolation film 23 is provided as a single unit. The first isolation film 23 has a Z-folded structure. Specifically, in the first direction Z, the first isolation film 23 is bent in a Z-shape to form the Z-folded structure. The first isolation film 23 with the Z-folded structure includes only two end portions, reducing the risk of internal short circuits caused by shrinkage of the first isolation film 23, thereby improving safety.

[0068] Referring to 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 electrode sheets and opposing each other in the first direction Z. The surface of the second portion 23b facing away from the electrode sheets 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 electrode sheets serves as the second surface 202 of the electrode assembly 20 and is connected to the first insulating layer. The first portions 23a, second portions 23b, and third portions 23c of the first separator 23 are integrally configured to form a wound structure, within which the plurality of electrode sheets are located. Specifically, the first separator 23 is wound around one end of the first separator 23 in sequence around the second direction Y to form a wound structure, where n is an integer greater than or equal to 1. That is, n electrode sheets are disposed between each pair of adjacent first portions 23a. Figure 11 shows three electrode sheets disposed between two adjacent first portions 23a. When n is greater than or equal to 2, a second separator 24 is also disposed between the plurality of electrode sheets between two adjacent first portions 23a. The second isolation film 24 is made of an insulating material to prevent the multiple pole pieces between two adjacent first portions 23a from directly contacting each other and causing a short circuit. The material of the second isolation film 24 can include at least one of polyolefin, polyvinylidene fluoride, polyethylene terephthalate, cellulose, polyimide, polyamide, spandex, or polyphenylene phthalate.

[0069] The integral first separator 23 is configured in a wound structure. The first separator 23 as a whole restrains the multiple electrode sheets in the first direction Z and the third direction X, eliminating the need for additional second and third insulating layers to restrain the electrode assembly 20 in the first and third directions Z and X. Compared to second and third insulating layers restraining the electrode assembly 20 in the first and third directions Z and X, the wound structure of the first separator 23 provides a weaker bond to the electrode sheet edges in the third direction X, facilitating electrolyte flow through and adequately wetting the electrode sheets in the third direction X. Furthermore, the first separator 23 includes a second portion 23b and a third portion 23c located outside the multiple electrode sheets. The first insulating layer 50 is connected to the second and third portions 23b and 23c of the first separator 23. The surface roughness of the first separator 23 is greater than that of the electrode sheet current collectors, enhancing the adhesion between the first insulating layer 50 and the electrode assembly 20 and reducing the risk of the first insulating layer 50 becoming detached.

[0070] Referring to FIG12 , one embodiment of the present application further provides an electrical device 1, which includes the electrochemical device 100 described above. The electrical device 1 of the present application may be, but is not limited to, a laptop computer, a pen-type computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup electronic source, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large household battery, and a lithium-ion capacitor, etc.

[0071] The present application is described in detail below through specific examples and comparative examples. The present application is described using a soft-pack cell as an example of an electrochemical device and in conjunction with a specific preparation process and testing method. Those skilled in the art should understand that the preparation method described in this application is merely an example, and any other suitable preparation method is within the scope of this application.

[0072] Example 1

[0073] The slurry formed by mixing the inorganic particle material and the binder is applied at intervals on the surface of the substrate layer to form a plurality of first inorganic particle layers set at intervals, and then the binder is applied on the surface of the plurality of first inorganic particle layers to form a plurality of first bonding layers to obtain a plurality of first coating layers set at intervals, and then the slurry formed by mixing the inorganic particle material and the binder is applied at intervals on the other surface of the substrate layer to form a plurality of second inorganic particle layers set at intervals, and then the binder is applied on the surface of the plurality of second inorganic particle layers to form a plurality of second bonding layers to obtain a plurality of second coating layers set at intervals, thereby obtaining a first isolation film. The relationship between the width D1 of the first coating layer and the distance D2 between two adjacent first coating layers is D1=0.3D2, and the angle θ1 between the first coating layer and the side of the substrate layer is 45°.

[0074] An electrode assembly is formed by stacking a first separator and a plurality of electrode sheets, wherein the first separator has a wound structure, three electrode sheets are disposed between the first portions of two adjacent first separators, and the surfaces of the second and third portions of the first separator facing away from the electrode sheets serve as the first and second surfaces of the electrode assembly. A first insulating layer is bonded to the first, second, and second end surfaces of the electrode assembly, wherein the relationship between the width W2 of the first insulating layer and the width W1 of the electrode assembly is: W2 = 0.8W1.

[0075] The electrode assembly and the electrolyte are encapsulated in an aluminum-plastic film to obtain an electrochemical device.

[0076] Example 2-13

[0077] The difference from the first embodiment is that at least one of the values ​​of D1 / D2, W2 / W1, and the angle θ1 is different.

[0078] Comparative Example 1

[0079] The difference from Example 1 is that the slurry is continuously coated on the surface of the substrate layer to form the first inorganic particle layer and the 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 the first adhesive layer. In other words, the multiple first coating layers and the multiple second coating layers spaced apart in Example 1 are connected together.

[0080] The electrochemical devices of Comparative Example 1 and Examples 1-10, 12-13 were subjected to cycle tests, and the test results are recorded in Table 1. The cycle test steps include: charging the electrochemical device to 4.43V at a constant current of 1C at 45 degrees Celsius, then charging to 0.05C at a constant voltage, then standing for 5 minutes, and then discharging to 3.0V at 0.7C. The discharge capacity at this time, measured using a commercially available battery performance tester, is the initial discharge capacity of the electrochemical device, which is calculated as 100%; the above charge and discharge steps are cycled 1000 times in sequence, and the ratio of the discharge capacity of the electrochemical device after the cycle to the initial capacity multiplied by 100% is the capacity retention rate; the electrochemical device is fully charged according to the charging process, and the negative electrode plate interface and lithium deposition are observed.

[0081] Table 1

[0082] Comparing Comparative Example 1 with Examples 1-10, 12-13, it can be seen that when a first insulating layer having a relatively wide width is used to constrain the electrode assembly in the first direction, when the first coating layer and the second coating layer are continuously applied to both surfaces of the substrate layer, it will lead to severe electrolyte infiltration. A large amount of purple lithium precipitation will be generated in the main area of ​​the electrode (the area near the center of the electrode), which will affect the life of the electrochemical device. When the first coating layer and the second coating layer are applied intermittently on both surfaces of the substrate layer, the gaps between adjacent first coating layers and adjacent second coating layers reserve space for electrolyte transmission, improve the electrolyte infiltration effect, and increase the life of the electrochemical device. Therefore, Comparative Example 1 has the lowest cycle capacity retention rate.

[0083] By comparing Examples 1-3 and 9-10, it can be seen that when 0.3D2≤D1≤0.5 is satisfied, the interface of the negative electrode plate 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 isolation membrane and the electrode is too small, resulting in a low overall mechanical strength of the electrochemical device, which is prone to deformation during the cycle, leading to a poor interface; when D1 is too large, the reserved space for electrolyte transmission on the first isolation membrane is too small, resulting in poor wetting, and then causing a poor interface.

[0084] By comparing Examples 2, 7, 8, and 12-13, it can be seen that when 25°≤θ1≤65° is satisfied, the interface of the negative electrode plate 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 plate is easily deformed, resulting in a poor interface.

[0085] By comparing Examples 2 and 4-6, it can be seen that when 0.7W1≤W2 is satisfied, the interface of the negative electrode plate is good after cycling, and the electrochemical device has a high capacity retention rate; and as W2 / W2 increases, the cycle capacity retention rate shows a trend of first increasing and then remaining unchanged, and the electrochemical device has a higher capacity retention rate when W2≥0.85W1.

[0086] The electrochemical devices of Comparative Example 1 and Examples 2 and 14 were subjected to a hot box test, and the test results are recorded in Table 2. The steps of the hot box test include: charging the electrochemical device to 4.43V at a constant current of 0.2C at 25±5°C, and then charging to 0.01C at a constant voltage. The electrochemical device was heated to 140±2°C at a rate of 5±2°C / min, and then maintained for 60 minutes. The electrochemical device was observed to see if there were any failure phenomena such as fire and explosion. If not, it passed the hot box test, otherwise it failed. The hot box test pass rate of 20 electrochemical devices was counted. After the test, the electrochemical device was disassembled to observe whether the diaphragm shrank.

[0087] Table 2

[0088] By comparing Comparative Example 1 and Example 2, it can be seen that when the surfaces of the second part and the third part of the first isolation membrane serve as the first surface and the second surface of the electrode assembly, that is, when the electrode assembly is finished with the first isolation membrane, the first coating and the second coating are alternately coated on the two surfaces of the substrate layer, thereby improving the pass rate of the hot box test and improving the shrinkage of the first isolation membrane.

[0089] The electrochemical devices of Examples 1-6, 9, and 11 were drop tested, and the test results are recorded in Table 3. The steps of the drop test include: charging the electrochemical device to 4.43V at a constant current of 0.2C at 25±5°C, and then charging to 0.01C at a constant voltage. The electrochemical device was fixed in a drop test fixture and dropped 6 times in sequence on the 6 sides of the drop test fixture at a height of 1.8m. 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 3.0V, the electrochemical device was judged to have failed. If no damage occurred and the open circuit voltage was higher than 3.0V, it was judged to have not failed. The test was continued until failure, and the number of drops performed when the electrochemical device failed was recorded. The electrochemical device was then disassembled and analyzed to observe whether the diaphragm shrank.

[0090] Table 3

[0091] Comparing Examples 1-3 and 9, it can be seen that when 0.3D2 ≤ D1 ≤ 0.5D2 is satisfied, the electrochemical device experiences a high number of drops and exhibits excellent drop resistance. When D1 is too small, the bonding area between the first separator and the electrode piece is small, limiting the first separator's restraining effect on the entire electrode assembly. This increases the impact between the electrode pieces and between the electrode assembly and the housing, potentially leading to damage to the housing. Therefore, the electrochemical device of Example 9 exhibits the worst drop resistance.

[0092] Comparing Examples 2, 4-6, and 11, it can be seen that when 0.7W1≤W2 is satisfied, the electrochemical device experiences a high number of drops and exhibits good drop resistance. In Example 11, where W2 is too small, failure occurs due to shrinkage of the first isolation film during the drop process, resulting in the fewest drops and the worst drop resistance.

[0093] The above disclosure is only a preferred embodiment of the present application and certainly cannot be used to limit the present application. Therefore, equivalent changes made based on the present application are still within the scope covered by the present application.

Claims

1. An electrochemical device, It is characterized in that include: case; an electrode assembly, contained in the housing, the electrode assembly comprising a plurality of electrode sheets stacked along a first direction and a first isolation film disposed between the plurality of electrode sheets, the electrode assembly further comprising a first surface and a second surface opposite to each other in the first direction and a first end surface connected between the first surface and the second surface; A first insulating layer is bonded to the first surface, the second surface and the first end surface; and an electrolyte contained in the shell; The first isolation film includes a substrate layer and a first coating layer spaced apart on the surface of the substrate layer facing the adjacent pole piece.

2. The electrochemical device according to claim 1, It is characterized in that The first coating layer is in a strip shape, the substrate layer includes two side edges that are opposite to each other in a second direction that is perpendicular to the first direction, and the plurality of first coating layers are arranged obliquely relative to the side edges.

3. The electrochemical device according to claim 2, It is characterized in that When viewed along the first direction, the angle between the first coating and the side edge is θ 1 , 25°≤θ 1 ≤65°.

4. The electrochemical device according to claim 2, It is characterized in that When viewed along the first direction, the width of the first coating is D 1 , the distance between two adjacent first coating layers is D 2 , 0.3D 2 ≤D 1 ≤0.5D 2 .

5. The electrochemical device according to claim 2, It is characterized in that The first isolation film further includes a plurality of second coating layers, and the plurality of second coating layers are disposed at intervals on a surface of the substrate layer away from the plurality of first coating layers.

6. The electrochemical device according to claim 5, It is characterized in that The first coating layer and the second coating layer intersect each other in different planes.

7. The electrochemical device according to claim 1, It is characterized in that The first isolation membrane includes a plurality of first parts located in the plurality of pole pieces and a second part and a third part located outside the plurality of pole pieces and opposite to each other in the first direction, each of the first parts being arranged between two adjacent pole pieces, and the plurality of first parts, the second parts and the third part being arranged as a whole and forming a winding structure.

8. The electrochemical device according to claim 1, It is characterized in that In a third direction perpendicular to the first direction, the width of the electrode assembly is W 1 , the width of the first insulating layer is W 2 , 0.7W 1 ≤W 2 ≤W 1 .

9. The electrochemical device according to claim 8, It is characterized in that <h2 style=";text-align:left;direction:ltr">0.7W<h2 style=";text-align:left;direction:ltr"> 1 <h2 style=";text-align:left;direction:ltr"> ≤W<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> ≤0.95W<h2 style=";text-align:left;direction:ltr"> 1 <h2 style=";text-align:left;direction:ltr"> 。 10. The electrochemical device according to claim 9, It is characterized in that <h2 style=";text-align:left;direction:ltr">0.85W<h2 style=";text-align:left;direction:ltr"> 1 <h2 style=";text-align:left;direction:ltr"> ≤W<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> ≤0.95W<h2 style=";text-align:left;direction:ltr"> 1 <h2 style=";text-align:left;direction:ltr"> 。 11. The electrochemical device according to claim 1, It is characterized in that The first coating layer includes a first inorganic particle layer and a first bonding layer. The first inorganic particle layer is connected to the substrate layer. The bonding layer is arranged on the surface of the inorganic particle layer away from the substrate layer and is bonded to the adjacent pole piece.

12. The electrochemical device according to claim 1, It is characterized in that The first coating layer includes inorganic particles and a binder.

13. The electrochemical device according to claim 1, It is characterized in that The electrochemical device also includes a second insulating layer, and the electrode assembly also includes a second end face connected between the first surface and the second surface, defining the length direction of the electrode assembly as a second direction, the first surface and the second surface are opposite to each other in the second direction, and the second insulating layer is connected to the first surface, the second surface and the second end face.

14. The electrochemical device according to claim 13, It is characterized in that The first insulating layer is a single-sided adhesive tape or a double-sided adhesive tape, and / or the second insulating layer is a single-sided adhesive tape or a double-sided adhesive tape.

15. The electrochemical device according to claim 1, It is characterized in that The electrochemical device also includes a first metal plate and a second metal plate, and the first metal plate and the second metal plate are both 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.

16. The electrochemical device according to claim 1, It is characterized in that The shell is a packaging bag.

17. An electrical device, It is characterized in that Comprising the electrochemical device according to any one of claims 1 to 16.

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