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 electric equipment comprising same TECHNICAL FIELD

[0001] The present application relates to the field of energy storage devices, and in particular to an electrochemical device and an electric equipment comprising the same. BACKGROUND

[0002] Electrochemical devices (e.g. 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 may catch fire and other safety problems when subjected to abnormal conditions such as extrusion, collision or puncture.

[0003] SUMMARY

[0004] One object of the present application is to provide a battery with good cycle performance and reduced risk of internal short circuit of the electrochemical device.

[0005] The present application provides an electrochemical device, comprising a shell, an electrode assembly, a first insulating layer and an electrolyte, the electrode assembly and the electrolyte being accommodated in the shell. The electrode assembly comprises a plurality of electrode sheets stacked in a first direction and a first separator film arranged between the plurality of electrode sheets. The electrode assembly further comprises a first surface and a second surface opposite 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 the first surface, the second surface and the first end surface. The first separator film comprises a substrate layer and a plurality of first coating layers arranged at intervals on a surface of the substrate layer facing the adjacent electrode sheets.

[0006] The present application provides an electrochemical device, comprising a shell, an electrode assembly, a first insulating layer and an electrolyte, the electrode assembly and the electrolyte being accommodated in the shell. The electrode assembly comprises a plurality of electrode sheets stacked in a first direction and a first separator film arranged between the plurality of electrode sheets. The electrode assembly further comprises a first surface and a second surface opposite 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 the first surface, the second surface and the first end surface. The first separator film comprises a substrate layer and a plurality of first coating layers arranged at intervals on a surface of the substrate layer facing the adjacent electrode sheets.

[0007] In some possible implementations, the first coating layer is in the shape of a strip, the substrate layer comprises two side edges opposite in a second direction perpendicular to the first direction, and the plurality of first coating layers are arranged obliquely relative to the side edges. Thus, the bonding force between the first coating layer and the adjacent electrode sheet is continuously distributed on each edge of the electrode assembly, improving the deformation resistance of the electrode assembly and the cycle performance.

[0008] In some possible implementations, the first coating layer forms an angle θ1 with the side edge when viewed in the first direction, and 25°≤θ1≤65°. When the angle θ1 is within the range, the adhesion between the first coating layer and the edge of the pole piece can be maintained, the edge deformation of the pole piece can be suppressed, and the cycle performance can be improved.

[0009] In some possible implementations, the first coating layer has a width D1, and a spacing D2 between two adjacent first coating layers when viewed in the first direction, and 0.3D2≤D1≤0.5D2. When D1>0.5D2, the space available for the electrolyte to transport is reduced when the area of the pole piece is constant, and the poor electrolyte wetting exacerbates the lithium precipitation problem of the pole piece, affecting the cycle performance. When D1<0.3D2, the adhesion area between the first coating layer and the pole piece is reduced, the adhesion is reduced, the deformation resistance is also reduced accordingly, and the cycle performance is affected.

[0010] In some possible implementations, the first isolation film further includes a plurality of second coating layers, and the plurality of second coating layers are arranged at intervals on the surface of the substrate layer away from the plurality of first coating layers. The gap between two adjacent second coating layers provides space for electrolyte transmission, improves electrolyte wetting, further improves the lithium precipitation problem of the pole piece caused by poor electrolyte wetting, and improves the cycle performance.

[0011] In some possible implementations, the first coating layer and the second coating layer are intersected in different planes, and the gap between the two adjacent first coating layers and the gap between the two adjacent second coating layers are staggered, further improving the electrolyte wetting, further improving the lithium precipitation problem of the pole piece caused by poor electrolyte wetting, and improving the cycle performance.

[0012] In some possible implementations, the first isolation film further 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 in the first direction, each first portion is arranged between two adjacent pole pieces, and the plurality of first portions, the second portion and the third portion are arranged in one body and form a winding structure. The first isolation film is arranged in a winding structure, and binds the plurality of pole pieces in a plurality of different directions, without the need to arrange an additional insulation layer to bind the plurality of pole pieces in a specific direction. Furthermore, the first insulation layer is connected to the second portion and the third portion of the first isolation film, increases the adhesion between the first insulation layer and the electrode assembly, reduces the risk of the first insulation layer falling off, and further reduces the risk of the first isolation film causing internal short circuit due to shrinkage.

[0013] In some possible implementations, in a third direction perpendicular to both the first direction and the second direction, a width of the electrode assembly is W1, and a width of the first insulating layer is W2, 0.7W1≤W2≤W1. When the width W1 of the electrode assembly and the width W2 of the first insulating layer are within the range, the adhesion of the first insulating layer to the first end face can be maintained, the risk of internal short circuit caused by shrinkage of the first isolation film can be reduced, and the safety performance can be improved.

[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 arranged on a surface of the inorganic particle layer away from the substrate layer and is in contact with the adjacent pole piece. The first adhesive layer is in contact with the pole piece, the interfacial adhesion between the first isolation film and the pole piece is improved, the swelling deformation of the electrochemical device when gas is generated inside is reduced, and the cycle performance is improved.

[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 face connected between the first surface and the second surface, a length direction of the electrode assembly is defined as a second direction, the first surface and the second surface are opposite in the second direction, and the second insulating layer is connected to the first surface, the second surface, and the second end face. The second insulating layer connected to the first surface, the second surface, and the second end face of the electrode assembly reduces the risk of internal short circuit caused by shrinkage of one end of the first isolation film close to the second end face.

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

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

[0020] In some possible implementations, the electrochemical device further 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 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.

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

[0022] The application also provides a power utilization device including any of the electrochemical devices described above. BRIEF DESCRIPTION OF DRAWINGS

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

[0024] FIG. 1 is a first direction view of an electrochemical device according to an embodiment of the present application;

[0025] FIG. 2 is a first direction view of an electrode assembly of the electrochemical device shown in FIG. 1, viewed from a side where a first surface is located;

[0026] FIG. 3 is a first direction view of the electrode assembly shown in FIG. 2, viewed from a side where a second surface is located;

[0027] FIG. 4 is a second direction view of the electrode assembly shown in FIG. 2;

[0028] FIG. 5 is a cross-sectional view of the electrode assembly shown in FIG. 2, taken along V-V;

[0029] FIG. 6 is a cross-sectional view of the electrode assembly shown in FIG. 4, taken along VI-VI;

[0030] FIG. 7 is a first direction view of a first separator film of the electrode assembly shown in FIG. 6, viewed from a side close to the first surface of the electrode assembly;

[0031] FIG. 8 is a first direction view of the first separator film shown in FIG. 7, viewed from a side close to the second surface of the electrode assembly;

[0032] FIG. 9 is a first direction view of a first separator film according to another embodiment of the present application;

[0033] FIG. 10 is a second direction view of an electrode assembly according to another embodiment of the present application;

[0034] FIG. 11 is a second direction view of an electrode assembly according to still another embodiment of the present application;

[0035] FIG. 12 is a schematic view of a structure of an electric device according to an embodiment of the present application.

[0036] Main element symbol explanation Electrochemical device 100 Case 10 Electrode assembly 20 First metal plate 30 Second metal plate 40 First separator 23 First tab 21 Second tab 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 material layer 231 First coating layer 232 Gap G1, G2, G3 First inorganic particle layer 232a First adhesive layer 232b Side edge 231a Second coating layer 233 Second inorganic particle layer 233a Second adhesive layer 233b Second portion 23b Third portion 23c Second separator24 electric device 1 first direction Z second direction Y third direction X DETAILED DESCRIPTION

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

[0038] Hereinafter, the embodiments of the present application will be described in detail. However, the present application can 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 so that the present application will be thorough and complete, and fully convey the scope of the present application to those skilled in the art.

[0039] In addition, for brevity and clarity, in the drawings, the size or thickness of various components, layers, etc. can be exaggerated. Throughout the document, the same numbers refer to the same elements. In addition, it should be understood that when an element A is referred to as being "connected" to an element B, the element A can be directly connected to the element B, or there can be an intervening element C and the element A and the element B can be indirectly connected to each other.

[0040] Further, "may" used when describing embodiments of the present application means "one or more embodiments of the present application".

[0041] The specific terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be understood that the terms "comprising", "including", "containing" and / or "having" when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It will be understood that, although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

[0042] "Plural" in the present application means two or more.

[0043] In the present application, an electrochemical device includes any device in which an electrochemical reaction occurs, and specific examples thereof include primary batteries, secondary batteries, fuel cells, solar cells, or capacitors of all kinds. An example of the electrochemical device is a lithium secondary battery, which can 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 FIG. 1, an embodiment of the present application provides an electrochemical device 100 including a case 10, an electrode assembly 20 (shown in FIGS. 2 and 3) and an electrolyte contained in the case 10, a first metal plate 30, and a second metal plate 40. In some embodiments, the case 10 is a metal case, such as a steel case or an aluminum case, etc. In other embodiments, the case 10 is a package bag obtained by packaging with a packaging film, i.e., the electrochemical device 100 can be a soft-packaged battery. FIGS. 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 a plurality of electrode assemblies 20.

[0045] As shown in FIG. 4, the electrode assembly 20 includes a plurality of electrode tabs and a first separator film 23 disposed between the plurality of electrode tabs. The plurality of electrode tabs are stacked in a first direction Z to form a tab structure. In the present embodiment, the first direction Z refers to the thickness direction of the electrode assembly 20. The plurality of electrode tabs include first electrode tabs 21 and second electrode tabs 22 having opposite polarities. The first separator film 23 is disposed between adjacent first electrode tabs 21 and second electrode tabs 22 to reduce the risk of direct contact short circuit between the first electrode tabs 21 and the second electrode tabs 22.

[0046] The first metal plate 30 and the second metal plate 40 are electrically connected to the electrode assembly 20, respectively, and extend from the case 10 to connect external elements (not shown). Specifically, the first tab 21 includes a first current collector 211 and a first active material layer 212 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 tab 22 includes a second current collector 221 and a second active material layer 222 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 tab 21 is a positive electrode tab, and the second tab 22 is a negative electrode tab. Specifically, the first current collector 211 includes at least one of Ni, Ti, Cu, Ag, Au, Pt, Fe, Al, and combinations thereof, and the first active material layer 212 includes a positive active material, which can include at least one of lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel cobalt manganate, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxyphosphate, lithium-rich manganese-based material, lithium nickel cobalt aluminum phosphate, 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 active material, which can be selected from at least one of a graphite-based material, an alloy-based material, lithium metal, and alloys thereof. The graphite-based material can be selected from at least one of artificial graphite and natural graphite, and the alloy-based material can be selected from at least one of silicon, silicon oxide, tin, and titanium sulfide.

[0048] Referring to FIGS. 2-4, 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 opposite in a first direction Z. In some embodiments, surfaces of two outermost electrode tabs of the plurality of electrode tabs serve as the first surface 201 and the second surface 202, respectively. In some embodiments, surfaces of current collectors of two outermost electrode tabs of the plurality of electrode tabs serve as the first surface 201 and the second surface 202. The second end surface 203 and the first end surface 204 are opposite in a second direction Y and are 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 can extend directly out of the housing 10 or can extend through another metal plate that extends out of the housing 10. The first side surface 205 and the second side surface 206 are opposite in a third direction X and are connected between the first surface 201 and the second surface 202. In the present disclosure, the third direction X refers to the width direction of the electrode assembly 20, 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 separation film 23 includes at least a first portion 23a disposed in the plurality of electrode tabs. In some embodiments, the first separation film 23 includes a plurality of first portions 23a, each of which is configured to separate adjacent first electrode tabs 21 and second electrode tabs 22. The plurality of first portions 23a are separately disposed, i.e., the plurality of first portions 23a are configured as independent separation films. In this case, the electrode assembly 20 is obtained by alternately stacking the first electrode tabs 21, the first portions 23a, and the second electrode tabs 22. The edges of the first portions 23a of the first separation film 23 extend beyond the edges of the electrode tabs in the third direction X and the second direction Y to separate the adjacent first electrode tabs 21 and second electrode tabs 22. In some embodiments, the edges of the first portions 23a of the first separation film 23 on both sides in the second direction Y serve as the second end surface 203 and the first end surface 204, respectively, and the edges of the first portions 23a of the first separation film 23 on both sides in the third direction X serve as the first side surface 205 and the second side surface 206, respectively.

[0050] Referring to FIGS. 2, 3 and 5, the electrochemical device 100 further comprises a first insulating layer 50. The first insulating layer 50 is generally in the shape of a sheet, which 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, and is bonded to the first surface 201, the second surface 202 and the first end surface 204. In FIG. 5, the first insulating layer 50 is connected to the surfaces of the current collectors serving as the first and second electrode tabs. The first insulating layer 50 binds the electrode assembly 20 in the first direction Z and the second direction Y, reduces the risk of the first end of the first portion 23a of the first separator 23 near the first end surface 204 shrinking in the second direction Y during thermal abuse and mechanical abuse, causing the first and second electrode tabs 21 and 22 to contact and short circuit, and can also reduce the stress on the first end surface 204 during drop, reducing the risk of damage to the electrode tabs.

[0051] Referring to FIGS. 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. In the case of W2<0.7W1, the width of the first insulating layer 50 is small, the connection area between the first insulating layer 50 and the first end surface 204 is small, i.e., the connection area between the first insulating layer 50 and the first separator 23 is small, so the first separator 23 is prone to shrinkage during thermal abuse and drop, causing internal short circuit. In some embodiments, W2≤0.95W1, which balances the tolerance of setting the first insulating layer 50 during manufacturing, and improves the electrolyte wetting effect of the first end surface 204.

[0052] Referring to FIGS. 2 to 4, in some embodiments, the electrochemical device 100 further comprises a fourth insulating layer 60 and a third insulating layer 70. The fourth insulating layer 60 is generally in the shape of a sheet, which 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 the first surface 201, the second surface 202 and the first side surface 205. 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 end of the first portion 23a of the first separator 23 near the first side surface 205 shrinking in the third direction X. The third insulating layer 70 is generally in the shape of a sheet, which 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 the first surface 201, the second surface 202 and the second side surface 206. 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 end of the first portion 23a of the first separator 23 near the second side surface 206 shrinking in the third direction X.

[0053] Referring to FIGS. 2, 3 and 5, in some embodiments, the electrochemical device 100 further comprises a second insulation layer 80. The second insulation layer 80 is generally sheet-shaped, 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 surface 203, and connected to the first surface 201, the second surface 202 and the second end surface 203. The second insulation 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 separator 23 shrinking in the second direction Y near the end of the second end surface 203. In the present embodiment, the electrochemical device 100 comprises three second insulation layers 80, one of which is arranged between the first metal plate 30 and the second metal plate 40, one of which is arranged between the first metal plate 30 and the first side surface 205, and one of which is arranged between the second metal plate 40 and the second side surface 206, thereby increasing the connection area of the second insulation layer 80 with the second end surface 203, maintaining the adhesion of the second insulation layer 80 with the second end surface 203, and further reducing the risk of the first portion 23a of the first separator 23 shrinking near the end of the second end surface 203.

[0054] In some embodiments, the first insulation layer 50, the fourth insulation layer 60, the third insulation layer 70 and the second insulation layer 80 are all adhesive and bonded to the electrode assembly 20. The materials of the first insulation layer 50, the fourth insulation layer 60, the third insulation layer 70 and the second insulation layer 80 can all be single-sided adhesive or double-sided adhesive.

[0055] Referring to FIG. 6, the first separator 23 has a laminated film structure. Specifically, the first separator comprises a substrate layer 231 and a plurality of first coating layers 232 arranged at one surface of the substrate layer 231, the first coating layers 232 bonding the first tab 21. In another embodiment, the first coating layers 232 can also bond the second tab 22. Adjacent two first coating layers 232 have a gap G1 therebetween. The gaps G1 between the plurality of first coating layers 232 reserve space for electrolyte transmission, and after electrolyte injection, the electrolyte can pass through the gaps G1 and fully soak the tabs. In this case, even if the first insulation layer 50 is arranged to bind the electrode assembly 20 in the first direction Z and the second direction Y, the electrolyte can still soak the tabs through the gaps G1.

[0056] In an embodiment, the first coating layer 232 comprises a first inorganic particle layer 232a and a first adhesive layer 232b arranged in a stack. The first inorganic particle layer 232a is in contact with the substrate layer 231, and the first adhesive layer 232b is arranged on the surface of the first inorganic particle layer 232a away from the substrate layer 231. The first adhesive layer 232b can adhere to the electrode tab, improve the interfacial adhesion between the first separator film 23 and the electrode tab, and reduce the swelling deformation of the electrochemical device 100 when gas is generated inside the electrochemical device 100, i.e., 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 FIG. 7, the first coating layer 232 is arranged in a strip shape on the surface of the substrate layer 231, and a plurality of first coating layers 232 are arranged parallel to each other. The substrate layer 231 comprises two opposite side edges 231a in the second direction Y. The included angle between the first coating layer 232 and the side edge 231a is θ1. The first coating layer 232 is arranged obliquely relative to the side edge 231a, i.e., 0° < θ1 < 90°, so that the adhesion between the first coating layer 232 and the electrode tab is continuously distributed on the edges of the electrode assembly in the second direction Y and the third direction X, improving the deformation resistance of the electrode assembly and the cycle performance. In some embodiments, 25° ≤ θ1 ≤ 65°, so as to maintain the adhesion of the first coating layer 232 to the edges of the electrode tab, suppress the deformation of the edges of the electrode tab, and thus improve the cycle performance. When θ1 < 25°, the first coating layer 232 is relatively flat in the third direction X, which may

[0058] As shown in FIG. 7, in some embodiments, the width of the first coating layer 232 is D1, and the distance between two adjacent first coating layers 232 is D2, as viewed in the first direction Z. D1 and D2 satisfy the following relationship: 0.3D2 ≤ D1 ≤ 0.5D2. When D1 > 0.5D2, the space available for electrolyte transmission is reduced under the condition that the area of the electrode tab is constant, which leads to poor electrolyte wetting and causes the electrode tab to release lithium, affecting the cycle performance. When D1 < 0.3D2, the adhesion area between the first coating layer 232 and the electrode tab is reduced, the adhesion is decreased, the deformation resistance is also reduced, and the cycle performance is affected.

[0059] As shown in FIG. 6, in some embodiments, the first isolation film 23 further includes a plurality of second coating layers 233 arranged at intervals on a surface of the substrate layer 231, which is located between the first coating layer 232 and the second coating layer 233. The second coating layer 233 bonds the second pole piece 22 when the first coating layer 232 bonds the first pole piece 21. The second coating layer 233 also has a gap G2 between adjacent two second coating layers 233 as a channel for the electrolyte to transport. Therefore, the arrangement of the second coating layer 233 further improves the wettability of the electrolyte, further reduces the problem of lithium precipitation of the pole piece caused by poor wettability of the electrolyte, and thus improves the cycle performance.

[0060] The second coating layer 233 includes a second inorganic particle layer 233a and a second adhesive layer 233b arranged in layers. The second inorganic particle layer 233a is in contact with the substrate layer 231, and the second adhesive layer 233b is arranged on the surface of the second inorganic particle layer 233a away from the substrate layer 231.

[0061] In some embodiments, the substrate layer 231 includes a polymer film, a multilayer polymer film, or a non-woven fabric formed by any one of the following polymers or a mixture of two or more of the following polymers: polyolefin, polyvinylidene fluoride, polyethylene terephthalate, cellulose, polyimide, polyamide, spandex, and polyphenylene terephthalamide. Such polymers have high thermal stability and are easy to be surface treated, so that the first coating layer 232 and the second coating layer 233 are easy to be coated on the substrate layer 231. In addition, such polymers have good toughness and are easy to be bent.

[0062] The first inorganic particle layer 232a and the second inorganic particle layer 233a each include an inorganic particle 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 can further include a binder that bonds the inorganic particle material together. The binder can include polyvinylidene fluoride or a copolymer of vinylidene fluoride-hexafluoropropylene.

[0063] The first adhesive layer 232b and the second adhesive layer 233b each include a bonding material including at least one of a copolymer of vinylidene fluoride-hexafluoropropylene, a copolymer of vinylidene fluoride-trichloroethylene, polymethyl methacrylate, polyacrylic acid, a polyacrylic acid salt, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, a copolymer of ethylene-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-butadiene, polyvinyl alcohol, polyvinyl ether, polytetrafluoroethylene, polyhexafluoropropylene, a copolymer of styrene-butadiene, or polyvinylidene fluoride. These polymers can produce strong bonding to bond the first separator 23 and the first tab 21 or the second tab 22 together.

[0064] Referring to FIG. 8, in some embodiments, the second coating layer 233 is provided in a strip shape, and a plurality of second coating layers 233 are provided parallel to each other. The second coating layer 233 forms an angle θ2 with the side edge 231a. The second coating layer 233 is inclined with respect to the side edge 231a, i.e., 0° < θ2 < 90°. In some embodiments, 25° ≤ θ2 ≤ 65°, to maintain the adhesion of the second coating layer 233 to the edge of the tab and further suppress deformation of the edge of the tab, thereby improving the cycle performance. In the case of θ2 < 25°, since the second coating layer 233 is relatively flat with respect to the third direction X, the adhesion of the first separator 23 to the tab in the second direction Y can be reduced, which can cause deformation of the edge of the electrode assembly 20 in the third direction X, affecting the cycle life. In the case of θ2 > 65°, since the second coating layer 233 is relatively flat with respect to the second direction Y, the adhesion of the first separator 23 to the tab in the third direction X can be reduced, which can cause deformation of the edge of the electrode assembly 20 in the second direction Y, affecting the cycle life.

[0065] As shown in FIG. 8, the first coating layer 232 and the second coating layer 233 are intersected in different planes, and the first coating layer 232 and the second coating layer 233 form an angle θ3 therebetween, 0° < θ3 < 180°. In this way, the gaps G1 between the plurality of first coating layers 232 and the gaps G2 between the plurality of second coating layers 233 are staggered, further improving the electrolyte infiltration effect. As shown in FIG. 9, in another embodiment, the first coating layer 232 and the second coating layer 233 can also be provided in parallel, in which case the angle θ1 of the first coating layer 232 with respect to the side edge 231a is equal to the angle θ2 of the second coating layer 233 with respect to the side edge 231a.

[0066] Referring to FIG. 9, each first coating layer 232 or each second coating layer 233 can be discontinuously arranged, such as being arranged in a plurality of blocks or a plurality of islands on the surface of the substrate layer 231. At this time, the angle θ1 between the first coating layer 232 and the side edge 231a is the angle between the connecting line of the plurality of block portions or the plurality of island portions 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 connecting line of the plurality of block portions or the plurality of island portions and the side edge 231a. Among them, each first coating layer 232 or each second coating layer 233 arranged discontinuously is also provided with a gap G3, which can serve as a channel for the transmission of electrolyte, further improving the electrolyte transmission performance.

[0067] Referring to FIG. 10, in another embodiment, the plurality of first portions 23a of the first separation film 23 are configured in one body, i.e., the first separation film 23 is arranged in one body. The first separation film 23 has a Z-shaped folding structure. Specifically, in the first direction Z, the first separation film 23 is bent in a Z shape to form a Z-shaped folding structure. The first separation film 23 having a Z-shaped folding structure only includes two end portions, reducing the risk of internal short circuit caused by shrinkage of the first separation film 23, thereby improving safety performance.

[0068] Referring to FIG. 11, in another embodiment, the first separation film 23 further includes a second portion 23b and a third portion 23c located outside the plurality of pole pieces and opposite in the first direction Z, wherein the surface of the second portion 23b away from the pole piece is connected with the first insulating layer as the first surface 201 of the electrode assembly 20, and the surface of the third portion 23c away from the pole piece is connected with the first insulating layer as the second surface 202 of the electrode assembly 20. The plurality of first portions 23a, the second portion 23b and the third portion 23c of the first separation film 23 are configured in one body and form a winding structure in which the plurality of pole pieces are located. Specifically, the first separation film 23 is wound around every n pole pieces in the second direction Y with one end thereof as the center to form a winding structure, where n is an integer greater than or equal to 1. That is, n pole pieces are arranged between every two adjacent first portions 23a. In FIG. 11, three pole pieces are arranged between every two adjacent first portions 23a. In the case where n is greater than or equal to 2, a second separation film 24 is also arranged between the plurality of pole pieces between every two adjacent first portions 23a. The second separation film 24 is made of an insulating material and is used to prevent the plurality of pole pieces between every two adjacent first portions 23a from directly contacting and short-circuiting. The material of the second separation film 24 can include at least one of polyolefin, polyvinylidene fluoride, polyethylene terephthalate, cellulose, polyimide, polyamide, spandex or polyphenylene terephthalamide.

[0069] The first isolation film 23 configured in a winding structure is integrally bound to the plurality of pole pieces in the first direction Z and the third direction X, and the second insulating layer and the third insulating layer for binding the electrode assembly 20 in the first direction Z and the third direction X are not additionally configured. Compared with the case where the second insulating layer and the third insulating layer for binding the electrode assembly 20 in the first direction Z and the third direction X are configured, the first isolation film 23 configured in the winding structure is weaker in binding the edge of the pole piece in the third direction X, which is conducive to the flow of electrolyte through the edge of the pole piece in the third direction X and the full impregnation of the pole piece. Furthermore, the first isolation film 23 includes the second portion 23b and the third portion 23c located outside the plurality of pole pieces, the first insulating layer 50 is connected to the second portion 23b and the third portion 23c of the first isolation film 23, the surface roughness of the first isolation film 23 is greater than the surface roughness of the current collector of the pole piece, the adhesion of the first insulating layer 50 to the electrode assembly 20 is increased, and the risk of the first insulating layer 50 falling off is reduced.

[0070] Referring to FIG. 12, the application also provides a power consuming device 1 including the above electrochemical device 100. The power consuming device 1 of the application can be, but is not limited to, a notebook computer, a pen input computer, a mobile computer, an electronic book player, a portable telephone, a portable facsimile machine, a portable copying machine, a portable printer, a head-mounted stereo headphone, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic organizer, a calculator, a memory card, a portable recorder, a radio, a backup power source, an electric motor, an automobile, a motorcycle, a power-assisted bicycle, a bicycle, a lighting appliance, a toy, a game machine, a clock, an electric tool, a flashlight, a camera, a household large storage battery, and a lithium ion capacitor, etc.

[0071] The application is described in detail below through specific examples and comparative examples. The electrochemical device is taken as an example of a soft-packaged battery cell, and the application is described in combination with a specific preparation process and a test method. It should be understood by those skilled in the art that the preparation method described in the application is only an example, and any other suitable preparation method is within the scope of the application.

[0072] Example 1

[0073] The slurry formed by mixing the inorganic particulate material and the binder is intermittently coated on the surface of the substrate layer to form a plurality of first inorganic particulate layers arranged at intervals, and then the adhesive material is coated on the surface of the plurality of first inorganic particulate layers to form a plurality of first adhesive layers to obtain a plurality of first coating layers arranged at intervals, and then the slurry formed by mixing the inorganic particulate material and the binder is intermittently coated on the other surface of the substrate layer to form a plurality of second inorganic particulate layers arranged at intervals, and then the adhesive material is coated on the surface of the plurality of second inorganic particulate layers to form a plurality of second adhesive layers to obtain a plurality of second coating layers arranged at intervals, to obtain a first isolation film. Wherein the relationship between the width D1 of the first coating layer and the distance D2 between the adjacent two first coating layers is D1 = 0.3D2, and the included angle θ1 between the first coating layer and the side edge of the substrate layer is 45°

[0074] The first isolation film and a plurality of pole pieces are rolled to obtain an electrode assembly, wherein the first isolation film has a winding structure, three pole pieces are arranged between the first parts of two adjacent first isolation films, and the second part and the third part of the first isolation film are away from the surface of the pole piece as the first surface and the second surface of the electrode assembly. The first insulation layer is bonded to the first surface, the second surface and the second end surface of the electrode assembly, wherein the relationship between the width W2 of the first insulation layer and the width W1 of the electrode assembly is: W2 = 0.8W1.

[0075] The electrode assembly and the electrolyte are packaged into an aluminum plastic film to obtain an electrochemical device.

[0076] Examples 2-13

[0077] Different from example 1, at least one of the value of D1 / D2, the value of W2 / W1, and the value of the included angle θ1 is different.

[0078] Comparative example 1

[0079] Different from example 1, the slurry is continuously coated on the surface of the substrate layer to form the first inorganic particulate layer and the second inorganic particulate layer, and the slurry is continuously coated on the surface of the first inorganic particulate layer and the surface of the second inorganic particulate layer to form the first adhesive layer. That is, the plurality of first coating layers and the plurality of second coating layers arranged at intervals in example 1 are connected as a whole, respectively.

[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. Among them, the steps of the cycle test included: charging the electrochemical device to 4.43 V at 1 C constant current in 45 degrees Celsius, then constant voltage charging to 0.05 C, then standing for 5 min, then discharging to 3.0 V at 0.7 C, and the discharge capacity at this time was measured by a commercially available battery performance tester, which was the first discharge capacity of the electrochemical device, counted as 100%; sequentially cycling 1000 times according to the above charge and discharge steps, and the ratio of the discharge capacity of the electrochemical device after cycling to the first capacity multiplied by 100% was the capacity retention rate; the electrochemical device was fully charged according to the charging process, and the interface condition and lithium precipitation of the negative electrode plate were observed.

[0081] Table 1

[0082] Comparing Comparative Example 1 and Examples 1-10, 12-13, when the first insulating layer with a relatively wide width is used to constrain the electrode assembly in the first direction, when the first coating and the second coating are continuously coated on both surfaces of the substrate layer, it will cause serious electrolyte immersion failure, and a large amount of purple spot lithium precipitation will occur in the main body area of the electrode plate (the area close to the center of the electrode plate), which will affect the service life of the electrochemical device; and when the first coating and the second coating are intermittently coated on both surfaces of the substrate layer, the gap between the adjacent first coating and the adjacent second coating provides space for electrolyte transmission, improves the electrolyte immersion effect, and improves the service life of the electrochemical device. Therefore, the cycle capacity retention rate of Comparative Example 1 is the lowest.

[0083] Comparing Examples 1-3, 9-10, when 0.3D2≤D1≤0.5 is satisfied, the interface of the negative electrode plate after cycling is good, and the electrochemical device has a relatively high capacity retention rate; when D1 is too small, the adhesion area of the first separation film to the electrode plate is too small, resulting in low overall mechanical strength of the electrochemical device, which is prone to deformation during cycling, causing interface failure; when D1 is too large, the electrolyte transmission reserved space on the first separation film is too small, resulting in poor immersion, and further causing interface failure.

[0084] Comparing Examples 2, 7, 8, 12-13, when 25°≤θ1≤65° is satisfied, the interface of the negative electrode plate after cycling is good, and the electrochemical device has a relatively high capacity retention rate; when θ1 is too small or too large, the edge of the electrode plate is prone to deformation, causing interface failure.

[0085] Comparing Examples 2, 4-6, when 0.7W1≤W2 is satisfied, the interface of the negative electrode plate after cycling is good, and the electrochemical device has a relatively 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 when W2≥0.85W1, the electrochemical device has a higher capacity retention rate.

[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 included charging the electrochemical device to 4.43 V at 25 ± 5 °C at a constant current of 0.2 C, and then constant voltage charging to 0.01 C. The electrochemical device was heated to 140 ± 2 °C at a rate of 5 ± 2 °C / min, and then held for 60 min. Whether the electrochemical device had failure phenomena such as ignition and explosion was observed, and if not, the electrochemical device passed the hot box test, otherwise it failed. The pass rate of 20 electrochemical devices was counted. After the test, the electrochemical device was disassembled, and whether the shrinkage of the separator occurred was observed.

[0087] Table 2

[0088] Comparing Comparative Example 1 and Example 2, when the surfaces of the second part and the third part of the first separator film are used as the first surface and the second surface of the electrode assembly, i.e., when the first separator film is used to wrap the electrode assembly, the first coating and the second coating are spaced apart on the two surfaces of the substrate layer, the pass rate of the hot box test is improved, and the shrinkage of the first separator film is improved.

[0089] The electrochemical devices of Examples 1-6 and 9 and 11 were subjected to a drop test, and the test results are recorded in Table 3. The steps of the drop test included charging the electrochemical device to 4.43 V at 25 ± 5 °C at a constant current of 0.2 C, and then constant voltage charging to 0.01 C. The electrochemical device was fixed in a drop test fixture, and was dropped 6 times in turn according to the 6 faces of the drop test fixture at a height of 1.8 m. After each drop, whether the electrochemical device was damaged was observed, and the open circuit voltage of the electrochemical device was measured, and if the voltage was less than 3.0 V, the electrochemical device was determined to be invalid. If there was no damage and the open circuit voltage was higher than 3.0 V, the test was continued until the electrochemical device failed, and the number of drops performed when the electrochemical device failed was recorded. Subsequently, the electrochemical device was disassembled and analyzed, and whether the shrinkage of the separator occurred was observed.

[0090] Table 3

[0091] Comparing Examples 1-3 and 9, when 0.3D2≤D1≤0.5D2 is satisfied, the electrochemical device has more drop times and better drop resistance. When D1 is too small, the adhesion area of the first separator film to the pole piece is small, the binding effect of the first separator film on the whole electrode assembly is limited, and the mutual impact between the pole pieces and between the electrode assembly and the shell increases, which easily leads to damage of the shell. Therefore, the electrochemical device of Example 9 has the worst drop resistance.

[0092] From comparative examples 2, 4-6, 11, when 0.7W1≤W2 is satisfied, the electrochemical device has more drop times and better drop resistance. In example 11, W2 is too small, and failure caused by shrinkage of the first separator film occurs during the drop, the drop times are the least, and the drop resistance is the worst.

[0093] The above disclosure is only the preferred embodiments of the present application, and of course cannot be used to limit the present application, so the equivalent changes made by the present application still fall within the scope of the present application.

Claims

1. An electrochemical device, characterized by, The electrochemical device comprises: a housing; an electrode assembly accommodated in the housing, the electrode assembly comprising a plurality of electrode sheets stacked in a first direction and a first separator film arranged 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 bonded to the first surface, the second surface and the first end surface; and an electrolyte accommodated in the housing; wherein the first separator film comprises a substrate layer and a first coating layer arranged on a surface of the substrate layer facing the adjacent electrode sheet. The first coating layer is in a strip shape, the substrate layer comprises two side edges opposite to each other in a second direction perpendicular to the first direction, and the plurality of first coating layers are arranged obliquely relative to the side edges.

2. The electrochemical device of claim 1, wherein, When viewed in the first direction, an included angle between the first coating layer and the side edge is θ1, and 25°≤ θ1≤ 65°.

3. The electrochemical device of claim 2, wherein When viewed in the first direction, a width of the first coating layer is D1, a spacing between two adjacent first coating layers is D2, and 0.3D2≤ D1≤ 0.5D2.

4. The electrochemical device of claim 2, wherein The first separator film further comprises a plurality of second coating layers arranged on a surface of the substrate layer away from the plurality of first coating layers.

5. The electrochemical device of claim 2, wherein The first coating layer and the second coating layer are in different planes.

6. The electrochemical device of claim 5, wherein, The first separator film comprises a plurality of first portions located in the plurality of electrode sheets and a second portion and a third portion located outside the plurality of electrode sheets and opposite to each other in the first direction, each of the first portions is arranged between two adjacent electrode sheets, and the plurality of first portions, the second portion and the third portion are arranged in one body and form a winding structure.

7. The electrochemical device of claim 1, wherein In a third direction perpendicular to the first direction, a width of the electrode assembly is W1, and a width of the first insulating layer is W2, and 0.7W1≤ W2≤ W1.

8. The electrochemical device of claim 1, wherein, 0.7W1≤ W2≤ 0.95W1.

9. The electrochemical device of claim 8, wherein, 0.85W1≤ W2≤ 0.95W1.

10. The electrochemical device of claim 9, wherein The first coating layer comprises a first inorganic particle layer and a first adhesive layer, the first inorganic particle layer is connected to the substrate layer, and the adhesive layer is arranged on a surface of the inorganic particle layer away from the substrate layer and bonded to the adjacent electrode sheet.

11. The electrochemical device of claim 1, wherein, The first coating layer comprises inorganic particles and a binder.

12. The electrochemical device of claim 1, wherein, The electrochemical device further comprises a second insulating layer, the electrode assembly further comprises a second end surface connected between the first surface and the second surface, a length direction of the electrode assembly is defined 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 surface.

13. The electrochemical device of claim 1, wherein, The first insulating layer is single-sided adhesive tape or double-sided adhesive tape, and / or the second insulating layer is single-sided adhesive tape or double-sided adhesive tape.

14. The electrochemical device of claim 13, wherein, ​ 15. The electrochemical device of claim 1, wherein, The electrochemical device further includes a first metal plate and a second metal plate, each of which is connected to the electrode assembly; in a third direction perpendicular to the first direction, the electrode assembly further includes a second end surface opposite to the first end surface, and the first metal plate and the second metal plate extend out of the electrode assembly from the second end surface.

16. The electrochemical device of claim 1, wherein, The housing is a packaging bag.

17. An electrical device, characterized by An electrochemical device as described in any one of claims 1 to 16.

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