Separator for electrochemical device, electrochemical device and electrical equipment

Abstract

The present application discloses a separator for an electrochemical device, an electrochemical device and an electrical device. The separator includes a sealing layer, the sealing layer includes a middle part, an edge part surrounding and connected to the periphery of the middle part, the middle part is accommodated in the internal space of the outer package of the electrochemical device, and the edge part is used for sealing connection with the outer package. The present application connects the sealing layer of the separator to the outer package of the electrochemical device, thereby improving the stability of the sealing connection between the separator and the outer package of the electrochemical device, thereby effectively improving the service life of the electrochemical device. In addition, the thickness of the prepared separator can be effectively reduced, and the energy density of the electrochemical device can be improved.

Description

Technical Field

[0001] The present application relates to the field of electrochemistry, and in particular to a separator for an electrochemical device, an electrochemical device and an electrical equipment. Background Art

[0002] Electrochemical devices such as lithium-ion batteries have many advantages such as high volumetric and mass energy density, long cycle life, high nominal voltage, low self-discharge rate, small size, and light weight, and are widely used in the field of consumer electronics. Electrochemical devices use the method of connecting multiple cells in series to effectively increase the output voltage, while also having many advantages such as reducing the total heat generation of the cells, reducing temperature rise, and being compatible with winding and stacking structures.

[0003] When assembling multiple battery cells in series, it is necessary to achieve ion insulation between the cavities in series to avoid short circuits between the anode and cathode in different cavities after filling with electrolyte, and to avoid interference with adjacent cavities after the liquid electrolyte decomposes and fails under high voltage. In related technologies, the ion insulation function of each series cavity of the electrochemical device is achieved through a partition. The partition needs to be connected to the outer packaging of the electrochemical device. The ion insulation of the partition itself and the connection between the partition and the outer packaging will affect the ion insulation effect of two adjacent cavities in the electrochemical device. Summary of the invention

[0004] The embodiments of the present application provide a separator for an electrochemical device, an electrochemical device and an electrical equipment, which can solve the problem that it is difficult to achieve ion insulation between two adjacent cavities in the electrochemical device.

[0005] In a first aspect, an embodiment of the present application provides a separator for an electrochemical device, comprising:

[0006] The sealing layer comprises a middle part and an edge part surrounding and connected to the periphery of the middle part. The middle part is accommodated in the inner space of the outer package of the electrochemical device, and the edge part is used for sealing connection with the outer package.

[0007] In some exemplary embodiments, the sealing layer includes a thermoplastic polymer, so that the separator can be directly connected to the outer packaging of the electrochemical device after the sealing layer is hot-melted, effectively improving the sealing strength of the separator and the outer packaging. In some exemplary embodiments, the melting point of the thermoplastic polymer ranges from 100°C to 200°C; the thermoplastic polymer includes: at least one of polypropylene, polyethylene, polyester plastic, γ-phthalimido-α-hydroxybutyric acid, anhydride-modified polypropylene, ethylene and its copolymers, cast polypropylene, polyimide, polytetrafluoroethylene, polyvinylidene fluoride and its derivatives.

[0008] In some exemplary embodiments, the partition further includes at least one barrier layer, the barrier layer has ion insulation properties, and the barrier layer is disposed on at least one side of the sealing layer; in the thickness direction of the stacking of the sealing layer and the barrier layer, the projection of the barrier layer at least covers the projection of the middle portion.

[0009] In some exemplary embodiments, the number of the barrier layers is two, and the two barrier layers are disposed on two opposite surfaces of the sealing layer.

[0010] In some exemplary embodiments, in a plane perpendicular to the stacking direction of the sealing layer and the barrier layer, the area of ​​the middle portion is S, the area of ​​the barrier layer is S1, the area of ​​the sealing layer is S2, and the partition satisfies S<S1≤S2 or S≤S1<S2.

[0011] In some exemplary embodiments, the middle portion of the sealing layer has a length and b width, the barrier layer has a1 length and b1 width, the sealing layer has a2 length and b2 width, and the partition satisfies: a<a1≤a2, b<b1≤b2, or a≤a1<a2, b≤b1<b2.

[0012] In some exemplary embodiments, the barrier layer is chemically bonded to the surface of the sealing layer by at least one of atomic layer deposition, molecular layer deposition, chemical vapor deposition, physical vapor deposition, electrodeposition or 3D printing, thereby effectively improving the strength of the connection between the sealing layer and the barrier layer so that the sealing layer and the barrier layer will not be easily peeled off.

[0013] In some exemplary embodiments, the barrier layer includes at least one of an oxide layer, a nitride layer, a metal layer, and an organic polymer;

[0014] The oxide layer includes at least one of an aluminum oxide layer, a zinc oxide layer, a zirconium oxide layer, a silicon oxide layer, and a silicon aluminum oxide layer;

[0015] The nitride layer includes at least one of an aluminum nitride layer, a zinc nitride layer, a zirconium nitride layer, a silicon nitride layer, and a silicon aluminum nitride layer;

[0016] The metal layer includes: at least one metal material or alloy material selected from Si, Zn, Al, Zr, Ti, V, Mg, Ni, Pr, Ce, Mn, Ta, In, Zn, Ga, Sn, Cd, Pb, Ni, Ti, Cu, Ag, Au, Pt, Fe, Co, Cr, and W;

[0017] The organic polymer includes at least one of vinylidene chloride-methyl acrylate, polyethylene, polypropylene, polyethylene terephthalate, random copolymer of ethylene vinyl alcohol, resin, polyacrylonitrile, polyvinylidene chloride, polyamide, polyimide-amide, polyurethane, polythiourea, polyethylene glycol or organic metal polymer.

[0018] In some exemplary embodiments, the separator has at least one of the following features:

[0019] (a) The first water vapor transmission rate M1 of the partition satisfies M1≤10 -3 g / (day·m 2 );

[0020] (b) the thickness of the sealing layer is H, and the range of H is 14 μm to 304 μm; the thickness of the barrier layer is h, and the range of h is 5 nm to 2000 nm;

[0021] (c) the sealing layer comprises an ion barrier sheet, wherein the ion barrier sheet comprises at least one of flaky graphene, hydrotalcite nanosheets, and boehmite sheets;

[0022] (d) the sealing layer further comprises a leveling layer, the leveling layer is connected to the barrier layer, the leveling layer has a low roughness relative to the surface of the barrier layer, and the leveling layer comprises one or more polymer materials such as epoxy resin, polypropylene resin, polyacrylate, etc.;

[0023] (e) The partition further comprises a reinforcing layer located on the surface of the sealing layer or the barrier layer, wherein the reinforcing layer is disposed on the surface of the barrier layer and / or the sealing layer, and the reinforcing layer comprises at least one of a polymer layer, a glass fiber layer, a carbon material layer, an elastic polymer layer, and an oxide layer.

[0024] In a second aspect, an embodiment of the present application provides an electrochemical device, comprising:

[0025] a partition as described above;

[0026] An outer package, wherein the partition is disposed inside the outer package and connected to the outer package to separate the inner space of the outer package into a plurality of first chambers;

[0027] an electrolyte disposed in each of the first chambers; and

[0028] A plurality of electrode assemblies are correspondingly disposed in each of the first chambers and in contact with the electrolyte.

[0029] In some exemplary embodiments, the outer packaging includes a connecting layer, which is connected to the edge portion of the partition, and the connecting layer includes a polymer, and the polymer includes at least one of polypropylene, polyethylene, polyester plastic, γ-phthalimido-α-hydroxybutyric acid, anhydride modified polypropylene, ethylene and its copolymers, cast polypropylene, polyimide, polytetrafluoroethylene, polyvinylidene fluoride and its derivatives.

[0030] In a third aspect, an embodiment of the present application provides an electrical device, including the electrochemical device as described above.

[0031] Based on the separator for electrochemical devices, electrochemical devices and electrical equipment of the embodiments of the present application, the sealing layer of the separator is connected to the outer packaging of the electrochemical device, which improves the stability of the sealing connection between the separator and the outer packaging of the electrochemical device, thereby effectively improving the service life of the electrochemical device. In addition, the thickness of the prepared separator can be effectively reduced, and the energy density of the electrochemical device can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 This is a cross-sectional view of a partition according to an embodiment of the present application in which a barrier layer is disposed on a single side of a sealing layer;

[0034] Figure 2 This is a cross-sectional view of a partition according to an embodiment of the present application in which the barrier layer is disposed on both sides of the sealing layer;

[0035] Figure 3 This is a cross-sectional view of a partition connected to an outer package according to an embodiment of the present application;

[0036] Figure 4a This is a front view of a sealing layer of a partition according to an embodiment of the present application;

[0037] Figure 4b This is a front view of a partition according to an embodiment of the present application;

[0038] Figure 5 This is a cross-sectional view of an embodiment of the present application in which the barrier layer completely covers the sealing layer;

[0039] Figure 6 A cross-sectional view of a partition having a leveling layer according to an embodiment of the present application;

[0040] Figure 7A cross-sectional view of a partition with a reinforcement layer according to an embodiment of the present application;

[0041] Figure 8 A schematic diagram of the three-dimensional structure of an electrochemical device according to an embodiment of the present application;

[0042] Fig. 9 An exploded view of an electrochemical device according to an embodiment of the present application;

[0043] Fig.10 A partial cross-sectional view of an electrochemical device according to an embodiment of the present application.

[0044] Reference numerals:

[0045] Electrical equipment

[0046] 10. Electrochemical device;

[0047] 100, partition; 110, sealing layer; 120, barrier layer; 130, reinforcement layer;

[0048] 101, middle part; 102, edge part;

[0049] 111, sealing layer; 112, leveling layer; 110a, barrier sheet;

[0050] 200, electrode assembly; 210, first electrode assembly; 220, second electrode assembly;

[0051] 310, positive electrode sheet; 311 positive current collector; 312 positive electrode active material;

[0052] 320, negative electrode sheet; 321 negative current collector; 322 negative electrode active material;

[0053] 400, diaphragm;

[0054] 510, positive electrode ear; 520, negative electrode ear;

[0055] 700, outer packaging; 710, external structural layer; 720, connecting layer; 700a, first chamber. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0057] The inventors found that in an electrochemical device, when a metal layer is used alone as a separator, the separator is easy to peel off from the structure connected to it, and the tensile strength of the metal layer is low, and there is a risk of tearing and breaking, resulting in a short circuit inside the battery cell; when a polymer is used alone as a separator, the barrier performance of the polymer itself is limited, and it is difficult to exert an effective barrier effect. If a sealing layer and a barrier layer are superimposed, the barrier layer is often made of metal materials, and the sealing layer is often made of polymers, then the barrier properties and tensile strength requirements can be taken into account, but at the same time, attention should be paid to the thickness of the separator after superposition to prevent the separator from occupying more space, resulting in an increase in the proportion of inactive substances in the electrochemical device, and thus resulting in a lower overall energy density (ED). In addition, attention should also be paid to the bonding strength of the sealing layer and the barrier layer, the separator and the outer packaging, etc., to prevent the bonding force from being limited and there is a risk of aging and peeling, which in turn causes the electrolyte to penetrate between the two layers of the peeled structure, and even penetrate to the outside, posing a safety hazard and affecting the service life of the electrochemical device. In order to solve the above problems, the embodiments of the present application provide a separator for an electrochemical device, an electrochemical device, and an electrical equipment.

[0058] It should be noted that in the specific implementation of the present application, lithium-ion batteries are used as an example of electrochemical devices to explain the present application, but the electrochemical devices of the present application are not limited to lithium-ion batteries. Figure 1 and Figure 2 , which is a schematic structural diagram of a separator 100 for an electrochemical device 10 according to an embodiment of the present application, the separator 100 includes a sealing layer 110 and at least one barrier layer 120 .

[0059] The sealing layer 110 includes a middle portion 101 and an edge portion 102 surrounding and connected to the periphery of the middle portion 101. Figure 3 As shown, the middle portion 101 is used to be accommodated in the inner space of the outer package 700, and the edge portion 102 is used to be sealed and connected to the outer package 700. The middle portion 101 and the edge portion 102 are integrally formed with the same material.

[0060] Each barrier layer 120 has ion insulation, and the barrier layer 120 is disposed on at least one side of the sealing layer 110, and the barrier layer 120 is directly connected to the sealing layer 110. In the thickness direction of the sealing layer 110 and the barrier layer 120 stacked (that is, the thickness direction of the partition 100), the projection of the barrier layer 120 at least covers the projection of the middle part 101, so that the barrier layer 120 is located in the cavity of the outer package 700, and the barrier layer 120 is located on the surface of the partition 100 to block the migration of ions in two adjacent cavities.

[0061] Among them, the edge part 102 of the sealing layer 110 surrounds the periphery of the middle part 101, and the outer packaging 700 is connected to the entire edge part 102 of the sealing layer 110, so that when the outer packaging 700 is connected to the partition 100, a fully enclosed structure is formed at the periphery of the middle part 101 of the sealing layer 110, so that any two adjacent first chambers 700a divided by the partition 100 in the outer packaging 700 are independent of each other.

[0062] The shape of the separator 100 of the embodiment of the present application is selected based on the shape of the electrochemical device 10. For example, the separator 100 may be in a quadrilateral, circular or other heterogeneous structure. Taking the electrochemical device 10 as a lithium-ion battery as an example, the separator 100 is in a rectangular shape, the middle portion 101 of the sealing layer 110 is in a rectangular shape, and the edge portion 102 is a rectangular frame surrounding the middle portion 101.

[0063] In a plane perpendicular to the stacking direction of the sealing layer 110 and the barrier layer 120, the area of ​​the middle part 101 of the sealing layer 110 is S, the area of ​​the barrier layer 120 is S1, and the area of ​​the sealing layer 110 is S2. The partition 100 satisfies the conditional formula (1): S<S1≤S2 or S≤S1<S2. Within the area range of the conditional formula (1), after the partition 100 is connected to the outer package 700, both the ion barrier requirement and the requirement of the sealed connection between the partition 100 and the outer package 700 can be met. It should be noted that the area requirement of the conditional formula (1) is not limited to the case where the sealing layer 110 is rectangular. As long as the barrier layer 120 completely covers the middle part 101 of the sealing layer 110 in the thickness direction, the partition 100 of any shape satisfies the requirement of the conditional formula (1).

[0064] like Figure 4a and Figure 4b As shown, when the sealing layer 110 is rectangular, the middle portion 101 of the sealing layer 110 has a length a and a width b, the barrier layer 120 has a length a1 and a width b1, the sealing layer 110 has a length a2 and a width b2, and the separator 100 satisfies: a<a1≤a2, b<b1≤b2, or a≤a1<a2, b≤b1<b2, that is, illustratively, in the thickness direction of the separator 100, the projection of the barrier layer 120 may overlap with the projection of the middle portion 101 of the sealing layer 110; or, as shown in FIG. Figure 5 As shown, the projection of the barrier layer 120 can cover the projection of the middle part 101 of the sealing layer 110 while covering the projection of the edge part 102 of the sealing layer 110, so that the barrier layer 120 is also located between the edge part 102 of the sealing layer 110 and the outer packaging 700, so as to effectively improve the ion insulation at the connection between the partition 100 and the outer packaging 700.

[0065] In some exemplary embodiments, the sealing layer 110 includes a polymer that can be heat-sealed and connected to the outer packaging 700, so that the edge portion 102 of the sealing layer 110 can be connected to the outer packaging 700 after hot melting. The process has low difficulty, high feasibility, and high packaging reliability. For example, the edge portion 102 of the sealing layer 110 is placed between two layers of outer packaging 700, and then the edge portion 102 of the sealing layer 110 is connected to the outer packaging 700 by hot rolling, thereby dividing the chamber in the outer packaging 700 into multiple independent first chambers 700a.

[0066] When the number of the barrier layer 120 is one, the barrier layer 120 is connected to one side of the sealing layer 110. When the number of the barrier layer 120 is two, the two barrier layers 120 are disposed on two opposite surfaces of the sealing layer 110. In the thickness direction of the partition 100, the projections of the two barrier layers 120 may be completely overlapped or partially overlapped. The embodiment of the present application does not specifically limit the shape of the two barrier layers 120, as long as the projection of the barrier layer 120 covers the projection of the middle part 101 of the sealing layer 110 in the thickness direction of the partition 100 and meets the area requirement of the above conditional formula (1).

[0067] In some exemplary embodiments, the barrier layer 120 includes at least one of an oxide layer, a nitride layer, a metal layer, and an organic polymer, and these compounds make the barrier layer 120 have ion insulation. It can also be ensured that when the sealing layer 110 is hot-melt-connected to the outer package 700, the barrier layer 120 at the edge portion 102 of the sealing layer 110 has less interference with the hot-melt connection between the sealing layer 110 and the outer package 700.

[0068] Exemplarily, the oxide layer in the barrier layer 120 includes at least one of an aluminum oxide layer, a zinc oxide layer, a zirconium oxide layer, a silicon oxide layer, and a silicon aluminum oxide layer.

[0069] Exemplarily, the nitride layer in the barrier layer 120 includes at least one of an aluminum nitride layer, a zinc nitride layer, a zirconium nitride layer, a silicon nitride layer, and a silicon aluminum nitride layer.

[0070] Exemplarily, the metal layer in the barrier layer 120 includes: a metal compound composed of at least one element selected from the group consisting of Si, Zn, Al, Zr, Ti, V, Mg, Ni, Pr, Ce, Mn, Ta, In, Zn, Ga, Sn, Cd, Pb, Ni, Ti, Cu, Ag, Au, Pt, Fe, Co, Cr, and W.

[0071] Exemplarily, the organic polymer in the barrier layer 120 includes at least one of vinylidene chloride-methyl acrylate, polyethylene, polypropylene, polyethylene terephthalate, a random copolymer of ethylene vinyl alcohol, a resin, polyacrylonitrile, polyvinylidene chloride, polyamide, polyimide-amide, polyurethane, polythiourea, polyethylene glycol or an organic metal polymer, such as methyl aluminum.

[0072] Exemplarily, the melting point range of the polymer in the sealing layer 110 is 100°C to 200°C, preferably 120°C to 160°C, and the polymer layer includes at least one of polypropylene, polyethylene, polyester plastic, γ-phthalimido-α-hydroxybutyric acid, anhydride modified polypropylene, ethylene and its copolymers, cast polypropylene, polyimide, polytetrafluoroethylene, polyvinylidene fluoride and its derivatives.

[0073] In the separator 100 described in the present application, the barrier layer 120 is chemically bonded to the surface of the sealing layer 110 to improve the connection stability between the sealing layer 110 and the barrier layer 120, so that the barrier layer 120 and the sealing layer 110 will not be easily peeled off. In addition, the barrier layer 120 is directly connected to the sealing layer 110, and there is no need to set other bonding structures between the sealing layer 110 and the barrier layer 120, which reduces the thickness of the prepared separator 100 as much as possible, reduces the proportion of ineffective substances, and can improve the energy density of the electrochemical device 10. In the case where the prepared separator 100 is relatively thin, the separator 100 can also be made flexible, and the anti-bending performance of the separator 100 is improved. For example, in the high-frequency bending area near the connection between the separator 100 and the outer package 700, the flexible separator 100 will not be easily bent and damaged.

[0074] In some exemplary embodiments, the barrier layer 120 is chemically bonded to the surface of the sealing layer 110 by at least one of atomic layer deposition (ALD), molecular layer deposition (MLD), chemical vapor deposition (CVD), physical vapor deposition (PVD), electrodeposition or 3D printing. When the material in the barrier layer 120 is first deposited on the surface of the sealing layer 110, it reacts with the functional groups of the polymer in the sealing layer 110 to form chemical bonds, so that the materials in the surfaces of the sealing layer 110 and the barrier layer 120 facing each other are cross-linked with each other, so that when the sealing layer 110 and the barrier layer 120 are both at a relatively thin thickness, the prepared separator 100 can have a higher density to block the spacers. The chemical bonding between the sealing layer 110 and the barrier layer 120 can be observed by transmission electron microscopy and energy spectrum analysis.

[0075] The prepared separator 100 is placed in a water vapor transmission rate tester, and the water vapor transmission rate of the separator 100 is tested at 38°C and 90% RH. For example, the first water vapor transmission rate M1 of the separator 100 satisfies: M1≤10 -3g / (day·m 2 ). By limiting the first water vapor permeability M1 of the separator 100, it is prevented that the water molecules in the electrolyte of the chambers on both sides of the separator 100 are intertwined to cause the water content in the chamber to exceed the standard. Preferably, M1≤10 -4 g / (day·m 2 ).

[0076] Furthermore, a simulated bending experiment can be performed to obtain the bent partition 100, and the bent partition 100 is placed in a water vapor transmission rate tester to test the second water vapor transmission rate M2 of the bent partition 100 at 38°C and 90% RH to further test the water permeability of the partition 100. For example, the second water vapor transmission rate M2 of the bent partition 100 satisfies: M2≤10 -1 g / (day·m 2 The separator 100 of the embodiment of the present application has good ion insulation and sealing properties while satisfying the first water vapor permeability M1 and the second water vapor permeability M2.

[0077] The simulated bending test method includes: cutting the partition 100 into 10cm*10cm squares, flipping and folding it 180 degrees along the diagonal, covering the diagonal and applying an external force of 300N to press the bent partition 100, removing the external force and flattening the partition 100 to obtain a bent partition 100; or, cutting the partition 100 into 10cm*10cm squares, using a tool to apply a force of 300N to the surface of the partition 100, and scratching three scratches, each scratch having a width of 1mm and a length of 10cm, to obtain a bent partition 100.

[0078] In some exemplary embodiments, the thickness of the sealing layer 110 is H, the thickness of the barrier layer 120 is h, and H>h, so that the sealing layer 110 has a sufficient thickness to provide support for the barrier layer 120, and the obtained separator 100 has flexibility and is not easy to bend or break. Further, the two parameters H and h satisfy the conditional formula (2): 0<h / H≤0.1, and further, the two parameters H and h satisfy the conditional formula (3): 0.001≤h / H≤0.01, and the thickness of the sealing layer 110 and the thickness of the barrier layer 120 are controlled within a suitable range, so that the barrier layer 120 is not too thick, which makes the obtained separator 100 hard and weak in bending resistance; and the thickness of the barrier layer 120 is not too thin to meet the ion barrier requirements.

[0079] Exemplarily, H ranges from 10 μm to 300 μm (including 10 μm and 300 μm), and further, H ranges from 30 μm to 100 μm. Exemplarily, h ranges from 5 nm to 2000 nm (including 5 nm and 2000 nm), and further, h ranges from 50 nm to 200 nm. The thickness of the separator 100 is M, and exemplary, L ranges from 14 μm to 304 μm (including 14 μm and 304 μm), and further, M ranges from 34 μm to 104 μm.

[0080] In some exemplary embodiments, the sealing layer 110 may further include an ion barrier sheet 110a, which also has ion insulation. When preparing the sealing layer 110, the polymer and the ion barrier sheet 110a may be mixed together to prepare the sealing layer 110. It should be noted that the ion barrier sheet 110a is a sheet structure with smaller particles obtained by crushing the ion barrier material, so that the ion barrier sheet 110a can be mixed evenly with the polymer to prepare the sealing layer 110. The ion barrier sheet includes at least one of flaky graphene, hydrotalcite nanosheets, and boehmite sheets.

[0081] In order to enable the barrier layer 120 to be formed more densely on the sealing layer 110 to improve the ion insulation, the surface of the sealing layer 110 used to connect the barrier layer 120 is as smooth as possible. Figure 6 As shown, the sealing layer 110 includes a sealing layer 111 and a leveling layer 112 connected to the sealing layer 111. The sealing layer 111 is used to be connected to the outer package 700, that is, the sealing layer 111 includes a polymer that can be heat-sealed and connected to the outer package 700. The leveling layer 112 is connected to the barrier layer 120. The surface of the leveling layer 112 used to connect the barrier layer 120 has low roughness. The leveling layer 112 includes a polyether-modified dimethyl polysiloxane copolymer. The leveling layer 112 is chemically bonded to the leveling layer 112. In the thickness direction of the partition 100, the projection of the leveling layer 112 completely covers the projection of the barrier layer 120. When the sealing layer 110 has an ion barrier sheet 110a, the ion barrier sheet 110a is distributed in the polymer of the sealing layer 111.

[0082] For example, the leveling layer 112 can be disposed on the surface of the sealing layer 111 by spraying, scraping, deposition, etc. The leveling layer 112 can include one or more polymer materials such as epoxy resin, polypropylene resin, polyacrylate, etc. The thickness of the leveling layer 112 ranges from 3nm to 10μm.

[0083] like Figure 7As shown, the separator 100 may also include a reinforcement layer 130 located on the outer layer, and the reinforcement layer 130 is connected to the surface of the barrier layer 120 and / or the sealing layer 110 to further adjust the structural strength and ion insulation of the prepared separator 100. For example, the reinforcement layer 113 may be disposed on the surface of the barrier layer 120 by spraying, scraping, deposition, etc. The reinforcement layer 113 may include one or more of a (light / heat, etc.) curable polymer layer, a glass fiber layer, a carbon material layer, an elastic polymer layer, and an oxide layer. The thickness of the reinforcement layer 113 is 2 μm to 100 μm.

[0084] The number of the reinforcing layers 130 may be one or two. When there are two reinforcing layers 130 , the two reinforcing layers 130 are disposed opposite to each other in the thickness direction of the partition 100 , and the sealing layer 110 and the barrier layer 120 are sandwiched between the two barrier layers 120 .

[0085] like Figure 8 and Fig. 9 As shown, the present embodiment also provides an electrochemical device 10, including an outer package 700, an electrolyte, a plurality of electrode assemblies 200 and the separator 100 as described above. Figure 3 The separator 100 is arranged in the outer package 700, the middle part 101 of the sealing layer 110 of the separator 100 is used to be accommodated in the internal space of the outer package 700, and the edge part 102 of the sealing layer 110 of the separator 100 is used to be sealed and connected with the outer package 700 to separate the internal space of the outer package 700 into multiple independent first chambers 700a, each of which has an electrode assembly 200 and an electrolyte to form an independent electrochemical unit.

[0086] like Fig.10 As shown, the outer package 700 includes an outer structural layer 710 and a connecting layer 720. The outer structural layer 710 can be made of packaging materials such as aluminum-plastic film. The outer structural layer 710 is used to define the internal space of the outer package 700. The connecting layer 720 is arranged on the inner surface of the outer structural layer 710, and the connecting layer 720 is used to connect with the partition 100, for example, the connecting layer 720 is hot-melt connected with the partition 100. Further, the material of the connecting layer 720 is the same as that of the sealing layer 110, so as to improve the connection strength between the outer package 700 and the partition 100. The connecting layer 720 can be set to cover the outer structural layer 710 completely, or the connecting layer 720 can be set to partially cover the outer structural layer 710 corresponding to the edge portion 102 of the sealing layer 110.

[0087] The electrode assembly includes a positive electrode sheet 310, a negative electrode sheet 320 and a separator 400. The separator 400 is disposed between the positive electrode sheet 310 and the negative electrode sheet 320 to block the positive electrode sheet 310 and the negative electrode sheet 320 and prevent the positive electrode sheet 310 and the negative electrode sheet 320 from contacting and short-circuiting. The positive electrode sheet 310 includes a positive current collector 311 and a positive electrode active material 312. The positive electrode active material 312 is disposed on the surface of the positive current collector 311. The negative electrode sheet 320 includes a negative current collector 321 and a negative electrode active material 322. The negative electrode active material 322 is disposed on the surface of the negative current collector 321. The positive electrode sheet 310 and the negative electrode sheet 320 can be spaced apart from or attached to the separator 400. The electrolyte is in contact with both the positive electrode sheet 310 and the negative electrode sheet 320, and the electrolyte penetrates into the separator 400. Each electrode assembly may lead out a positive electrode tab 510 and a negative electrode tab 520 . The positive electrode tab 510 is electrically connected to the positive current collector 311 , and the negative electrode tab 520 is electrically connected to the negative current collector 321 .

[0088] For example, in two adjacent electrode assemblies 200, the positive electrode ear 510 of the first electrode assembly 210 and the negative electrode ear 520 of the second electrode assembly 220 are connected in series, the negative electrode ear 520 of the first electrode assembly 210 and the positive electrode ear 510 of the second electrode assembly 220 are output electrodes, and the output voltage is the sum of the output voltages of the two electrochemical units. The positive electrode ear 510 and the negative electrode ear 520 of the electrode assembly 200 can be connected in series inside or outside the outer package 700 by direct welding or wire welding.

[0089] The positive electrode sheet 310, the negative electrode sheet 320 and the separator 400 of the electrode assembly 200 may be in a wound structure or a stacked structure, and the structures of the electrode assembly 200 in each first cavity 700a may be the same or different. The two electrochemical units located on opposite sides of the separator 400 may be symmetrical or asymmetrical. The outer package 700 of the electrochemical device 10 may be made of a hard or flexible material, and the positive electrode sheet 310, the negative electrode sheet 320 and the separator 400 may be bonded and fixed in the outer package 700.

[0090] There is no special limitation on the positive electrode sheet 310 of the present application. The positive current collector 311 can be any positive current collector 311 known in the art, such as aluminum foil, aluminum alloy foil or composite current collector, etc. The positive electrode active material 312 can be any positive electrode active material 312 in the prior art, and the positive electrode active material 312 includes at least one of NCM811, NCM622, NCM523, NCM111, NCA, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium iron manganese phosphate or lithium titanate.

[0091] There is no particular limitation on the negative electrode sheet 320 of the present application. The negative current collector 321 can be any negative current collector 321 known in the art, such as copper foil, aluminum foil, aluminum alloy foil or a composite current collector, etc. The negative electrode active material 322 can be any negative electrode active material 322 in the prior art, and the negative electrode active material 322 includes at least one of graphite, hard carbon, soft carbon, silicon, silicon carbon or silicon oxide, etc.

[0092] The electrolyte of the present application is not particularly limited, and any electrolyte known in the art can be used, and the electrolyte can be any of a gel state, a solid state and a liquid state. When the electrolyte is a liquid electrolyte, the liquid electrolyte includes a lithium salt and a non-aqueous solvent. The lithium salt is not particularly limited, and any lithium salt known in the art can be used, as long as the purpose of the present application can be achieved. For example, the lithium salt can include at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3 or LiPO2F2, etc. The non-aqueous solvent is not particularly limited as long as the purpose of the present application can be achieved. For example, the non-aqueous solvent may include at least one of a carbonate compound, a carboxylate compound, an ether compound, a nitrile compound or other organic solvents. The carbonate compound may include diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), ethyl methyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), carbon esters. At least one of butylene carbonate (BC), vinyl ethylene carbonate (VEC), fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate or trifluoromethylethylene carbonate.

[0093] The separator 400 of the present application is not particularly limited. For example, the separator 400 may be made of a material that is stable to the electrolyte of the present application. The separator 400 should have ion conductivity to allow ions to pass through the separator 400 and move between the positive electrode sheet 310 and the negative electrode sheet 320. At the same time, the separator 400 should also have electronic insulation to prevent the positive electrode sheet 310 and the negative electrode sheet 320 from contacting each other and preventing the positive electrode sheet 310 and the negative electrode sheet 320 from short-circuiting.

[0094] The embodiment of the present application also provides an electrical device, including the electrochemical device 10 as described above. For example, the electrical device may include a car, etc.

[0095] The present application will be further described in detail below by taking the electrochemical device 10 as a lithium-ion battery as an example in conjunction with specific embodiments.

[0096] Example 1

[0097] Preparation of electrode assembly 200: The positive electrode sheet 310, the negative electrode sheet 320 and the separator 400 are wound or stacked, and the positive electrode ear 510 is electrically connected to the positive current collector 311 of the positive electrode sheet 310, and the negative electrode ear 520 is electrically connected to the negative current collector 321 of the negative electrode sheet 320 to obtain the electrode assembly 200, and two electrode assemblies 200 are prepared (one of which is the first electrode assembly 210 and the other is the second electrode assembly 220), and the two electrode assemblies 200 have the same dimensions in the length direction, width direction, and thickness direction. The positive electrode ear 510 is made of aluminum, and the negative electrode ear 520 is made of nickel, and the positive electrode ear 510 and the negative electrode ear 520 are arranged on the same side.

[0098] Preparation of separator 100: A PP film with a hot melt packaging function and a thickness of 10 μm is provided as a sealing layer 110, and trimethyl aluminum and H 2 O is deposited on the two opposite surfaces of the sealing layer 110 as a reaction precursor, wherein trimethylaluminum reacts with the functional groups on the surface of PP to allow trimethylaluminum to be deposited on the surface of PP, and water further reacts with the trimethylaluminum deposited on the surface of PP, and -OH replaces the trimethyl group, and the reaction is cyclically generated to generate Al 2 O 3 , thereby forming a barrier layer 120. The thickness of each barrier layer 120 generated on the surface of the sealing layer 110 is 0.05 μm. Among them, the total thickness of the separator 100 is 10.05 μm, and the ratio of the thickness of the barrier layer 120 to the thickness of the sealing layer 110 is 0.005. In the thickness direction, the projection of the barrier layer 120 overlaps with the projection of the sealing layer 110, that is, S1= S2.

[0099] Assembly of the electrochemical device 10: Two outer packages 700 are provided, and the outer packages 700 are formed by stamping an aluminum-plastic film with a thickness of 150 μm to form a structure with a pit. The first electrode assembly 210 is placed in the pit of one of the outer packages 700, and the separator 100 covers the first electrode assembly 210, and the edge portion 102 of the sealing layer 110 of the separator 100 is connected to the outer package 700, and pressure is applied to preliminarily press the separator 100 and the outer package 700 to obtain a semi-finished product. Then the second electrode assembly 220 is placed on the semi-finished separator 100, and the other outer package 700 is placed with the pit facing downward to cover the second electrode assembly 220, so that the edge portion 102 of the sealing layer 110 of the separator 100 is placed between the two outer packages 700, and pressure is applied to the corresponding edge portion 102 of the sealing layer 110 to act on the two outer packages 700, and the edge portion 102 of the sealing layer 110 is hot-pressed at 150°C until it is sealed and connected to the two outer packages 700. The separator 100 divides the space inside the two outer packages 700 into two independent first chambers 700a. The positive electrode tabs 510 and the negative electrode tabs 520 of the two electrode assemblies extend out of the outer packages 700 to obtain a preformed product.

[0100] Liquid injection and packaging: The electrolyte is injected into each first chamber 700a through the opening on each outer package 700. After the liquid injection is completed, the opening of the outer package 700 is sealed.

[0101] Series connection: The positive electrode tab 510 of one electrode assembly is attached to the negative electrode tab 520 of the other electrode assembly and fixed by welding to connect the two electrode assemblies in series to obtain an electrochemical device 10 having two electrochemical units. The unwelded positive electrode tab 510 and negative electrode tab 520 in the electrochemical device 10 are connected to charge and discharge the electrochemical device 10. The two electrodes welded together are connected to monitor the voltage in the electrochemical device 10.

[0102] Example 2

[0103] The difference from Example 1 is that the thickness of the PP film is 30 μm, and the ratio of the thickness of the barrier layer 120 to the thickness of the sealing layer 110 is 0.0017.

[0104] Example 3

[0105] The difference from Example 1 is that the thickness of the PP film is 80 μm, and the ratio of the thickness of the barrier layer 120 to the thickness of the sealing layer 110 is 0.0006.

[0106] Example 4

[0107] The difference from Example 1 is that the thickness of the PP film is 100 μm, and the ratio of the thickness of the barrier layer 120 to the thickness of the sealing layer 110 is 0.0005.

[0108] Example 5

[0109] The difference from Example 1 is that the thickness of the PP film is 300 μm, and the ratio of the thickness of the barrier layer 120 to the thickness of the sealing layer 110 is 0.0002.

[0110] Example 6

[0111] The difference from Example 3 is that the thickness of the barrier layer 120 is 0.005 μm, and the ratio of the thickness of the barrier layer 120 to the thickness of the sealing layer 110 is 0.0001.

[0112] Example 7

[0113] The difference from Example 3 is that the thickness of the barrier layer 120 is 0.1 μm, and the ratio of the thickness of the barrier layer 120 to the thickness of the sealing layer 110 is 0.0013.

[0114] Example 8

[0115] The difference from Example 3 is that the thickness of the barrier layer 120 is 0.2 μm, and the ratio of the thickness of the barrier layer 120 to the thickness of the sealing layer 110 is 0.0025.

[0116] Example 9

[0117] The difference from Example 1 is that the thickness of the PP film is 76 μm, the thickness of the barrier layer 120 is 2 μm, and the ratio of the thickness of the barrier layer 120 to the thickness of the sealing layer 110 is 0.0263.

[0118] Example 10

[0119] The difference from Example 1 is that the thickness of the PP film is 80 μm, the thickness of the barrier layer 120 is 0.1 μm, and the three parameters of the area S of the middle portion 101 of the sealing layer 110, the area S1 of the barrier layer 120, and the area S2 of the sealing layer 110 satisfy the conditional formula: S<S1=S2. The ratio of the thickness of the barrier layer 120 to the thickness of the sealing layer 110 is 0.0013.

[0120] Embodiment 11

[0121] The difference from Example 10 is that the three parameters of the area S of the middle portion 101 of the sealing layer 110 , the area S1 of the barrier layer 120 , and the area S2 of the sealing layer 110 satisfy the conditional formula: S<S1<S2.

[0122] Example 12

[0123] The difference from Example 10 is that the area S of the middle portion 101 of the sealing layer 110 and the area S1 of the barrier layer 120 satisfy the conditional formula: S=S1.

[0124] Example 13

[0125] The difference from Example 1 is that the sealing layer 111 is made of a PE film with a thickness of 80 μm, the thickness of the barrier layer 120 is 0.1 μm, and the edge portion 102 of the sealing layer 110 is hot pressed at 120° C. to be sealed and connected to the two outer packages 700. The ratio of the thickness of the barrier layer 120 to the thickness of the sealing layer 110 is 0.0013.

[0126] Embodiment 14

[0127] The difference from Example 13 is that a polystyrene film with a thickness of 80 μm is used as the sealing layer 111 , and the edge portion 102 of the sealing layer 110 is heat-pressed at 240° C. until it is sealed and connected to the two outer packages 700 .

[0128] Embodiment 15

[0129] The difference from Example 1 is that a PP film with a thickness of 80 μm is used as the sealing layer 111, Al with a thickness of 0.1 μm is deposited on the surface of the sealing layer 110 to form a barrier layer 120, and the edge portion 102 of the sealing layer 110 is hot pressed at 150° C. to be sealed and connected to the two outer packages 700. The ratio of the thickness of the barrier layer 120 to the thickness of the sealing layer 110 is 0.0013.

[0130] Example 16

[0131] The difference from Example 15 is that: in the thickness direction of the sealing layer 110, a layer of Al is first molecularly deposited on the surface of the sealing layer 110. 2 O 3 Then, in Al 2 O 3 Polyimide is deposited on the surface to form a barrier layer 120 on the surface of the sealing layer 110. 2 O 3 The thickness of the barrier layer 120 formed of polyimide is 0.1 μm.

[0132] Embodiment 17

[0133] The difference from Example 7 is that: in the thickness direction of the sealing layer 110, the epoxy resin is first sprayed on the two opposite surfaces of the sealing layer 110 to form leveling layers 112 on the two opposite surfaces of the sealing layer 110, and the thickness of the leveling layer 112 is 10 nm. Then, a barrier layer 120 is deposited on the surface of each leveling layer 112.

[0134] Embodiment 18

[0135] The difference from Example 7 is that: in the thickness direction of the sealing layer 110, a layer of polyurethane acrylate is sprayed on the surface of each barrier layer 120 to form a reinforcement layer 130 on the surface of the barrier layer 120, and the thickness of the reinforcement layer 130 is 10 μm.

[0136] Embodiment 19

[0137] The difference from Example 13 is that boehmite flakes are mixed into the raw materials for preparing the PP film to obtain a sealing layer 110 with a thickness of 80 μm, and the edge portion 102 of the sealing layer 110 is heat-pressed at 150° C. to be sealed and connected to the two outer packages 700.

[0138] Embodiment 20

[0139] The difference from Example 13 is that a barrier layer 120 is provided on one side of the sealing layer 110 .

[0140] Embodiment 21

[0141] The difference from Example 13 is that three electrode assemblies and two layers of separators 100 are provided, and the electrode assemblies and separators 100 are alternately placed between two outer packages 700, the edge portion 102 of the sealing layer 110 of each separator 100 is placed between the two outer packages 700, and the edge portion 102 of each sealing layer 110 is hot pressed at 150°C until it is sealed and connected to the two outer packages 700.

[0142] Comparative Example 1

[0143] The difference from Example 1 is that the hot-melt PP material is uniformly dispersed in the dispersant N-methylpyrrolidone (NMP) to obtain a suspension, and the suspension is coated on the two opposite surfaces of the Al film using a glue coating machine, and the dispersant NMP in the suspension is dried at 150°C to obtain a packaging layer connected to the surface of the Al film, that is, the preparation of the partition 100 is completed, and the packaging layer is used for hot-melt connection with the outer package 700, and the Al film has ion insulation. In this comparative example, two packaging layers are connected to the two opposite surfaces of the Al film, the total thickness of the partition 100 is 120μm, the total thickness of the two packaging layers is 80μm, the thickness of the Al film is 40μm, and the ratio of the Al film thickness to the total thickness of the two packaging layers is 0.5. At this time, the area of ​​the packaging layer S2 = the area of ​​the barrier layer S1.

[0144] Comparative Example 2

[0145] The difference from Example 1 is that a PP film is used as the separator 100, and the total thickness of the separator 100 is 80 μm. The PP film has ion insulation and is connected to the outer package 700 by heat melting at 150°C.

[0146] Comparative Example 3

[0147] The difference from Example 1 is that Al is used alone as the partition 100, the total thickness of the partition 100 is 80 μm, the Al partition 100 has ion insulation, and the Al partition 100 is directly connected to the outer package 700 using packaging glue.

[0148] Comparative Example 4

[0149] The difference from Example 1 is that the thickness of the PP film is 80 μm, the thickness of the barrier layer 120 is 0.05 μm, and the ratio of the thickness of the barrier layer 120 to the thickness of the sealing layer 110 is 0.0006. After the partition 100 is folded along its diagonal line, the edge portion 102 of the sealing layer 110 of the partition 100 is hot-rolled and connected to the outer packaging 700.

[0150] The separator 100 for the electrochemical device 10 and the electrochemical device 10 in each embodiment and comparative example were tested using the following method:

[0151] Seal strength test: Remove the part of the outer packaging 700 and the partition 100 that are hot-melt connected from the electrochemical device 10, and cut it into a test strip with a width of 8 mm, ensuring that the outer packaging 700 on both sides of the test strip is intact, and obtain the sample to be tested. Use a high-speed rail tensile machine to tear the outer packaging 700 on both sides of the sample to be tested at an angle of 180° so that the two layers of outer packaging 700 are separated from each other. Record the stable tension when the two layers of outer packaging 700 are separated, and calculate the packaging strength based on this.

[0152] 50cls capacity retention rate: the number of internal series electrode assemblies is n, the electrochemical device 10 is charged from 3.0*nV to 4.45*nV at a charging rate of 2C at 25°C, and then discharged to 3.0*nV at a discharge rate of 0.2C. The discharge capacity this time is determined as the first discharge capacity. The above charge and discharge cycle is repeated 50 times, and the discharge capacity of the 50th discharge is measured. 50cls capacity retention rate = 50th discharge capacity / first discharge capacity.

[0153] Energy density test: The number of internal series electrode assemblies is n, the electrochemical device 10 is left at 25°C for 30 minutes, and is charged at a constant current of 0.05C charging rate to a voltage of 4.45*nV, and then the electrochemical device 10 is discharged at a rate of 0.05C to 3.00*nV, and the above charge / discharge steps are repeated for 3 cycles to complete the formation of the electrochemical device 10 to be tested. After the formation of the electrochemical device 10 is completed, it is charged at a constant current of 0.1C charging rate to a voltage of 4.45*nV, and then the electrochemical device 10 is discharged at a discharge rate of 0.1C to 3.00*nV, and its discharge capacity is recorded, and then its energy density at 0.1C discharge is calculated: energy density (Wh / L) = discharge capacity (Wh) / volume size (L) of the electrochemical device 10.

[0154] Drop test: drop the 6 sides and 4 corners of the electrochemical device 10 from a height of 1.5m respectively, one round for each of the 6 sides and 4 corners, five rounds in total, i.e. 50 times, the cells without heat generation, leakage, swelling or fire are considered to have passed, and the others are considered to have failed, thereby determining the proportion of cells that have passed.

[0155] Please see Table 1 for parameter settings of the above embodiments and comparative examples, and please see Table 2 for test results.

[0156] Table 1

[0157]

[0158] Table 2

[0159]

[0160] It can be seen from Table 1 that compared with comparative examples 1 to 3, the energy density of the electrochemical devices of Examples 1-21 of the present application (except Example 5) is increased. It can be seen that the electrochemical devices prepared using the separators of the embodiments of the present application, compared with the electrochemical devices prepared using the separators with the middle layer as the barrier layer and the two sides as the encapsulation layer, the separators using only the polymer, and the separators using only the barrier layer, the separators used in the electrochemical devices prepared in the embodiments of the present application are thinner, which greatly reduces the proportion of inactive substances in the battery cell, and the separators have better barrier properties and bonding properties, resulting in higher capacity, thereby achieving the technical effect of high energy density.

[0161] Compared with Comparative Examples 1 to 4, the ratio of the discharge capacity to the initial discharge capacity of the electrochemical devices of Examples 1-21 of the present application (except Examples 1, 2 and 6) after 50 cycles is basically unchanged, indicating that the embodiments of the present application have high electrolyte barrier properties, ensuring effective separation of the two electrochemical cavities. At the same time, the partition of this solution has good packaging with the edge of the packaging bag, which can effectively prevent the invasion of external water and oxygen, thereby having good cyclability.

[0162] It can be seen from Examples 3 to 21 and Comparative Example 3 that the drop damage ratio of the electrochemical device of the present application is significantly reduced, indicating that the partition prepared in the present application has good flexibility and is not prone to breakage and short circuit under external influences. It can be used in electrochemical devices to resist drop damage.

[0163] It can be seen from Examples 3 to 21 and Comparative Example 3 that the sealing strength between the outer packaging and the partition of the electrochemical device of the present application is significantly improved, indicating that the packaging method of the partition prepared in the present application is reliable and can have a good packaging effect when applied to electrochemical devices.

[0164] The same or similar numbers in the drawings of this embodiment correspond to the same or similar parts; in the description of this application, it should be understood that if the terms "upper", "lower", "left", "right", etc. indicate an orientation or position relationship based on the orientation or position relationship shown in the drawings, it is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0165] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A separator for an electrochemical device, characterized in that: include: The sealing layer comprises a middle portion and an edge portion surrounding and connected to the periphery of the middle portion, wherein the middle portion is accommodated in the inner space of the outer package of the electrochemical device, and the edge portion is used for sealing connection with the outer package; and A barrier layer, each of the barrier layers has ion insulation, and the barrier layer is disposed on at least one side of the sealing layer; in the thickness direction of the stacking of the sealing layer and the barrier layer, the projection of the barrier layer at least covers the projection of the middle part; The thickness of the sealing layer is H, and the range of H is 14 μm to 304 μm; the thickness of the barrier layer is h, and the range of h is 5 nm to 2000 nm.

2. The separator for an electrochemical device according to claim 1, characterized in that: The sealing layer comprises a thermoplastic polymer having a melting point ranging from 100° C. to 200° C.; The thermoplastic polymer includes at least one of polypropylene, polyethylene, polyester plastic, γ-phthalimido-α-hydroxybutyric acid, anhydride-modified polypropylene, ethylene and its copolymer, cast polypropylene, polyimide, polytetrafluoroethylene, polyvinylidene fluoride and its derivatives.

3. The separator for an electrochemical device according to claim 1, characterized in that: In a plane perpendicular to the stacking direction of the sealing layer and the barrier layer, the area of ​​the middle portion is S, the area of ​​the barrier layer is S1, the area of ​​the sealing layer is S2, and the partition satisfies S<S1≤S2 or S≤S1<S2; and / or, The middle part of the sealing layer has a length and b width, the barrier layer has a1 length and b1 width, the sealing layer has a2 length and b2 width, and the partition satisfies: a<a1≤a2, b<b1≤b2, or a≤a1<a2, b≤b1<b2.

4. The separator for an electrochemical device according to claim 1, characterized in that: The barrier layer is chemically bonded to the surface of the sealing layer by at least one of atomic layer deposition, molecular layer deposition, chemical vapor deposition, physical vapor deposition, electrodeposition or 3D printing.

5. The separator for an electrochemical device according to claim 1, characterized in that: The barrier layer includes at least one of an oxide layer, a nitride layer, a metal layer, and an organic polymer; The oxide layer includes at least one of an aluminum oxide layer, a zinc oxide layer, a zirconium oxide layer, a silicon oxide layer, and a silicon aluminum oxide layer; The nitride layer includes at least one of an aluminum nitride layer, a zinc nitride layer, a zirconium nitride layer, a silicon nitride layer, and a silicon aluminum nitride layer; The metal layer includes: at least one metal material or alloy material of Si, Al, Zr, V, Mg, Ni, Pr, Ce, Mn, Ta, In, Zn, Ga, Sn, Cd, Pb, Ti, Cu, Ag, Au, Pt, Fe, Co, Cr, and W; The organic polymer includes at least one of vinylidene chloride-methyl acrylate, polyethylene, polypropylene, polyethylene terephthalate, random copolymer of ethylene vinyl alcohol, resin, polyacrylonitrile, polyvinylidene chloride, polyamide, polyimide-amide, polyurethane, polythiourea, polyethylene glycol or organic metal polymer.

6. The separator for an electrochemical device according to any one of claims 2 to 5, characterized in that: The separator has at least one of the following features: (a) The first water vapor transmission rate M1 of the partition satisfies M1≤10 -3 g / (day·m 2 ); (b) the sealing layer comprises an ion barrier sheet, wherein the ion barrier sheet comprises at least one of flaky graphene, hydrotalcite nanosheets, and boehmite sheets; (c) the sealing layer further comprises a leveling layer, the leveling layer is connected to the barrier layer, the leveling layer has a low roughness relative to the surface of the barrier layer, and the leveling layer comprises one or more polymer materials; (d) The partition further comprises a reinforcing layer located on the surface of the sealing layer or the barrier layer, wherein the reinforcing layer is disposed on the surface of the barrier layer and / or the sealing layer, and the reinforcing layer comprises at least one of a polymer layer, a glass fiber layer, a carbon material layer, an elastic polymer layer, and an oxide layer.

7. An electrochemical device, characterized in that: include: A separator as claimed in any one of claims 1 to 6; An outer package, wherein the partition is disposed inside the outer package and connected to the outer package to separate the inner space of the outer package into a plurality of first chambers; an electrolyte, disposed in each of the first chambers; and A plurality of electrode assemblies are correspondingly disposed in each of the first chambers and in contact with the electrolyte.

8. The electrochemical device according to claim 7, characterized in that The outer packaging includes a connecting layer, the connecting layer is connected to the edge portion of the separator, and the connecting layer includes a polymer; The polymer includes at least one of polypropylene, polyethylene, polyester plastic, γ-phthalimido-α-hydroxybutyric acid, anhydride-modified polypropylene, ethylene and its copolymer, cast polypropylene, polyimide, polytetrafluoroethylene, polyvinylidene fluoride and its derivatives.

9. An electrical device, characterized in that: include: An electrochemical device as claimed in claim 7 or 8 above.

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