Separator for electrochemical device, electrochemical device and electronic device

Abstract

A separator for an electrochemical device, an electrochemical device and an electronic device. The separator for an electrochemical device has ion insulation, comprises an intermediate layer and an encapsulation layer, the encapsulation layer is located on the upper and lower surfaces of the intermediate layer; the material of the intermediate layer comprises at least one of a carbon material, a first polymer material or a metal material; the material of the encapsulation layer comprises a second polymer material; the temperature at which the encapsulation layer begins to soften is at least 10°C lower than the temperature at which the intermediate layer begins to soften. The reliability of ion insulation and encapsulation can be ensured by stacking three layers of composite membranes.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and in particular to a separator for an electrochemical device, an electrochemical device and an electronic device. Background Art

[0002] Lithium-ion batteries have many advantages, such as high volume 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. With the rapid development of electric vehicles and mobile electronic devices in recent years, people have higher and higher demands on battery energy density, safety, cycle performance, etc., and look forward to the emergence of new lithium-ion batteries with comprehensive performance improvements.

[0003] However, lithium-ion batteries are limited by their inherent electrochemical system, and the operating voltage of a single battery is usually difficult to exceed 5V. However, in the actual use of lithium-ion batteries, there are many requirements for high-voltage application scenarios, such as EV (Electric vehicle), ESS (Energy Storage System) and other application scenarios. In order to increase the output voltage of lithium-ion batteries, the prior art usually assembles multiple electrode assemblies in series. Conventional liquid electrolyte electrode assemblies need to realize the ion insulation function of the series cavity in their series structure to avoid internal short circuits between the anode and cathode electrodes with different potentials under liquid conditions, and at the same time, it is necessary to avoid the decomposition failure of conventional liquid electrolytes under high voltage. In addition, as part of the packaging structure, the separator has certain requirements for its mechanical strength, thickness, thermal stability, electrochemical stability and other parameters. Based on this, it is difficult for conventional single basic materials to meet the needs of separators for series electrode assemblies, and new separators need to be developed to achieve series isolation of single batteries. The commonly used methods for preparing partitions are: 1. Compounding a layer of sealing material for packaging on the surface of a high-temperature resistant dense insulating material; 2. Modifying the surface of the high-temperature resistant dense insulating material so that the insulating material can be directly and tightly bonded to the outer packaging, thereby achieving sealing.

[0004] However, the partitions made by the current technology using the first method are generally multi-layer stacks of similar polymer materials, with a large overall thickness. The material itself is prone to structural damage under high-temperature packaging conditions and has poor ion isolation performance. For the partitions prepared using the second method, it is difficult to reliably package the partition and the outer packaging, making specific applications difficult. Summary of the invention

[0005] The object of the present invention is to provide a separator for an electrochemical device, an electrochemical device and an electronic device, so as to improve the packaging reliability of a lithium ion battery.

[0006] A first aspect of the present invention provides a separator for an electrochemical device, which has ion insulation and includes an intermediate layer and a packaging layer, wherein the packaging layer is located on the upper and lower surfaces of the intermediate layer;

[0007] The material of the intermediate layer includes at least one of a carbon material, a first polymer material or a metal material;

[0008] The material of the encapsulation layer includes a second polymer material;

[0009] The temperature at which the encapsulation layer starts to soften is at least 10° C. lower than the temperature at which the intermediate layer starts to soften.

[0010] In one embodiment of the present invention, the edges around the two surfaces of the intermediate layer are covered by the encapsulation layer, and the area of ​​the encapsulation layer accounts for 30% to 100% of the area of ​​the intermediate layer.

[0011] In one embodiment of the present invention, at least one surface of the intermediate layer is entirely covered by the encapsulation layer.

[0012] In one embodiment of the present invention, the carbon material includes at least one of carbon felt, carbon film, carbon black, acetylene black, fullerene, conductive graphite film or graphene film.

[0013] In one embodiment of the present invention, the first polymer material includes: polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyetheretherketone, polyimide, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-co-chlorotrifluoroethylene), silicone, vinylon, polypropylene, anhydride-modified polypropylene, polyethylene, ethylene and its copolymers, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester, polysulfone, amorphous α-olefin copolymer or at least one of the derivatives of the above substances.

[0014] In one embodiment of the present invention, the metal material includes at least one of Ni, Ti, Ag, Au, Pt, Fe, Co, Cr, W, Mo, Pb, In, Zn or stainless steel.

[0015] In one embodiment of the present invention, the second polymer material includes: polypropylene, anhydride-modified polypropylene, polyethylene, ethylene and its copolymers, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyamide, polyester, amorphous α-olefin copolymer or at least one of the derivatives of the above substances.

[0016] A second aspect of the present invention provides an electrochemical device, comprising at least one separator as described above, at least two electrode assemblies, an electrolyte and an outer package, wherein the electrode assemblies are in an independently sealed chamber.

[0017] In one embodiment of the present invention, the outermost layer of the electrode assembly comprises a separator, and the separator is adjacent to the separator.

[0018] In one embodiment of the present invention, the outermost layer of at least one of the electrode assemblies comprises a separator, and the separator is adjacent to the separator; the outermost layer of at least one of the electrode assemblies comprises a current collector, and the current collector is adjacent to the other side of the separator.

[0019] In one embodiment of the present invention, the separator has electronic conductivity, the outermost layer of the electrode assembly comprises a current collector, the current collector is adjacent to the separator, and the current collectors of the electrode assemblies on both sides of the separator have opposite polarities.

[0020] In one embodiment of the present invention, the separator has electronic insulation properties, and the outermost layer of the electrode assembly comprises a current collector, which is adjacent to the separator.

[0021] A third aspect of the present invention provides an electronic device, which includes the electrochemical device described in the second aspect.

[0022] The present invention provides a separator for an electrochemical device, an electrochemical device and an electronic device. The separator for an electrochemical device has ion insulation, comprises an intermediate layer and an encapsulation layer, the encapsulation layer is located on the upper and lower surfaces of the intermediate layer; the material of the intermediate layer comprises at least one of a carbon material, a first polymer material or a metal material; the material of the encapsulation layer comprises a second polymer material; the temperature at which the encapsulation layer begins to soften is at least 10°C lower than the temperature at which the intermediate layer begins to soften. By stacking three layers of composite membranes, the reliability of ion insulation and encapsulation can be ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention and the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments and the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A schematic cross-sectional view of a partition in one embodiment of the present invention;

[0025] Figure 2 A schematic cross-sectional view of a partition in another embodiment of the present invention;

[0026] Figure 3 A schematic top view of a partition in one embodiment of the present invention;

[0027] Figure 4 A schematic cross-sectional view of an electrode assembly after packaging in one embodiment of the present invention;

[0028] Figure 5 Schematic diagram of the electrochemical device of Comparative Example 2 of the present invention;

[0029] Figure 6 Schematic diagram of the electrochemical device of Comparative Example 3 of the present invention;

[0030] Figure 7 Schematic diagram of the electrochemical device of Comparative Example 4 of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution, and advantages of the present invention more clearly understood, the present invention is further described in detail with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that in the specific embodiments of the present invention, the present invention is explained by taking a lithium ion battery as an example of an electrochemical device, but the electrochemical device of the present invention is not limited to a lithium ion battery.

[0033] like Figure 1 As shown, the present invention provides a separator for an electrochemical device, which has ion insulation, and comprises an intermediate layer 2 and an encapsulation layer 1, wherein the encapsulation layer 1 is located on the upper and lower surfaces of the intermediate layer 2;

[0034] The material of the intermediate layer 2 includes at least one of a carbon material, a first polymer material or a metal material;

[0035] The material of the encapsulation layer 1 includes a second polymer material;

[0036] The temperature (melting point or softening point) at which the encapsulation layer 1 starts to soften is at least 10° C. lower than the temperature at which the intermediate layer starts to soften.

[0037] A separator for an electrochemical device, wherein the middle layer is a structural layer, having high mechanical strength, high melting point or high softening point; and the two sides are encapsulation layers, which have low melting point or low softening point. Both the middle layer and the encapsulation layer have the advantages of good ion insulation ability, certain thermal stability, and thin thickness. The temperature at which the encapsulation layer begins to soften is at least 10°C lower than the temperature at which the middle layer begins to soften, which can ensure the reliability of the encapsulation and the effectiveness of the ion insulation. The separator can be realized by hot pressing and laminating three layers of different films, or by coating the encapsulation layer on both sides of the middle layer.

[0038] like Figure 2 As shown, in one embodiment of the present invention, the edges around the two surfaces of the intermediate layer 2 are covered by the encapsulation layer 1. That is, the main surface part of the intermediate layer 2 is not covered by the encapsulation layer. Figure 3 This is a schematic top view of such an embodiment. The area of ​​the encapsulation layer accounts for 30% to 100% of the area of ​​the middle layer, and the absolute width of the encapsulation layer is greater than 2 mm.

[0039] The edges of the two surfaces of the middle layer are covered by the packaging layer, which minimizes the coating amount and proportion of the packaging layer material, reduces the proportion of ineffective substances, and can improve the energy density of the electrode assembly.

[0040] In one embodiment of the present invention, at least one surface of the intermediate layer is entirely covered by the encapsulation layer.

[0041] In one embodiment of the present invention, the carbon material includes at least one of carbon felt, carbon film, carbon black, acetylene black, fullerene, conductive graphite film or graphene film.

[0042] In one embodiment of the present invention, the first polymer material includes polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyetheretherketone, polyimide, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-co-chlorotrifluoroethylene), silicone, vinylon, polypropylene, anhydride-modified polypropylene, polyethylene, other ethylene and its copolymers (such as EVA, EEA, EAA, EVAL), polyvinyl chloride, polystyrene, other types of polyolefins, polyether nitrile, polyurethane, polyphenylene ether, polyester, polysulfone, amorphous α-olefin copolymer or at least one of the derivatives of the above substances.

[0043] The middle layer is made of polymer material. Since the density of polymer material is lower than that of commonly used metal-based current collector materials, the weight of inactive substances can be reduced, thereby increasing the mass energy density of the electrode assembly. Compared with metal-based current collectors, the separator made of polymer material in the middle layer has a lower probability of generating conductive debris under mechanical abuse (nail penetration, impact, extrusion, etc.) and has a better wrapping effect on mechanically damaged surfaces. Therefore, the safety margin under the above-mentioned mechanical abuse can be improved, and the safety test pass rate can be increased.

[0044] In one embodiment of the present invention, the metal material includes at least one of Ni, Ti, Ag, Au, Pt, Fe, Co, Cr, W, Mo, Pb, In, Zn or stainless steel, and preferably includes at least one of Ni, Ti, Ag, Au, Pt, Fe or stainless steel.

[0045] In one embodiment of the present invention, the second polymer material comprises at least one of polypropylene, anhydride-modified polypropylene, polyethylene, other ethylene and its copolymers (such as EVA, EEA, EAA, EVAL), polyvinyl chloride, polystyrene, other polyolefins, polyether nitrile, polyurethane, polyamide, polyester, amorphous α-olefin copolymer or derivatives thereof. In one embodiment of the present invention, the thickness of the separator is 2 μm to 500 μm, preferably 5 μm to 50 μm, and more preferably 5 μm to 20 μm.

[0046] In one embodiment of the present invention, the temperature at which the intermediate layer material begins to soften is greater than 130°C, preferably greater than 150°C.

[0047] In one embodiment of the present invention, the temperature at which the encapsulation layer material begins to soften is 120°C to 240°C, preferably 130°C to 170°C.

[0048] It should be noted that when the first polymer material is selected as the intermediate layer, the materials of the partition intermediate layer and the encapsulation layer prepared by the present invention can be the same or different. When the same material is used, such as PP (polypropylene), it is necessary to ensure that the temperature at which the intermediate layer and the encapsulation layer begin to soften differs by more than 20°C.

[0049] In one embodiment of the present invention, the interfacial adhesion between the encapsulation layer and the intermediate layer is greater than 10 N / cm, preferably greater than 20 N / cm.

[0050] In one embodiment of the present invention, the interfacial adhesion between the encapsulation layer and the outer packaging is greater than 10 N / cm, preferably greater than 15 N / cm.

[0051] In one embodiment of the present invention, the ratio A of the cross-sectional area of ​​the encapsulation layer in the inner unsealed overflow glue area to the cross-sectional area of ​​the encapsulation layer in the encapsulation area is 0 to 20, preferably 0.5 to 5, and more preferably 0.5 to 2. The position in the middle of the two pole ears of the lithium ion battery is cut, and the cross section is taken. The SEM (scanning electron microscope) test is performed to calculate the overflow glue area area and the encapsulation area area in the SEM image. According to the above method, the overflow glue area area and the encapsulation area area at the same position of multiple lithium ion batteries are tested to obtain multiple overflow glue area areas and encapsulation area areas, and then the average values ​​of the overflow glue area area and the encapsulation area area are calculated respectively, and the ratio of the two average values ​​is the ratio A. Figure 4 : is a cross-sectional schematic diagram of the packaging area, the middle of the aluminum-plastic film 3 is the packaging layer, the left side is the packaging area 5, and the glue in the packaging area 5 is squeezed into the unsealed area through hot pressing of the upper and lower aluminum-plastic films 3 to form a glue overflow area 4.

[0052] When there is too much glue in the overflow area, there will be too many bulges in the overflow area, and the battery after packaging is easy to be damaged; when there is too little glue in the overflow area, the heat sealing effect is poor, and the battery after packaging is easy to be damaged, so the value of ratio A should not be too large or too small.

[0053] The present invention also provides an electrochemical device comprising at least one separator of the present invention, at least two electrode assemblies, an electrolyte and an outer package, wherein the electrode assemblies are in independent sealed chambers.

[0054] In one embodiment of the present invention, the electrochemical device comprises at least one separator of the present invention, the separator is sealed and connected to the outer packaging of the electrochemical device, and two independent sealed chambers are formed on both sides of the separator, each of which has an electrode assembly and an electrolyte to form an independent electrochemical unit, wherein the separator has electronic conductivity, and the two sides of the separator can be coated with electrode active materials of opposite polarities. Adjacent electrochemical units are connected in series through the electrodes containing the separator of the present invention to form a bipolar lithium-ion battery with a higher operating voltage.

[0055] In one embodiment of the present invention, the separator has electronic conductivity, and two adjacent electrode assemblies can each lead out a tab, and the tabs of the two electrode assemblies have opposite polarities. For example, when the side of the separator adjacent to electrode assembly A is coated with a positive electrode active material, and the side adjacent to electrode assembly B is coated with a negative electrode active material, the negative electrode tab is led out of electrode assembly A, and the positive electrode tab is led out of electrode assembly B. At this time, the output voltage between the two tabs is the sum of the output voltages of the two electrochemical units.

[0056] In one embodiment of the present invention, the separator has electronic insulation, and two adjacent electrode assemblies can each lead out two tabs, the positive tab of electrode assembly A and the negative tab of electrode assembly B are connected in series, the negative tab of electrode assembly A and the positive tab of electrode assembly B are output tabs, and the output voltage is the sum of the output voltages of the two electrochemical units. In one embodiment of the present invention, the separator has electronic conductivity, and the separator can lead out a tab for monitoring the working state of the lithium-ion battery.

[0057] In one embodiment of the present invention, the outermost layer of the electrode assembly comprises a separator, and the separator is adjacent to the separator.

[0058] In the present invention, the outermost layer of the electrode assembly may include at least one of a diaphragm or a current collector, depending on the winding or other finishing methods, for example, only a diaphragm, only a current collector, or a portion of the diaphragm and the other portion of the current collector; wherein the current collector may be in at least one of the states of the outermost layer not being coated with active material, partially being coated with active material, or the entire surface being coated with active material.

[0059] In one embodiment of the present invention, the electrochemical device of the present invention comprises at least one separator, which may have electronic insulation or electronic conductivity, and the separator is sealed and connected to the outer package, and separate sealed chambers are formed on both sides of the separator, each of which contains an electrode assembly and an electrolyte to form an electrochemical unit, wherein both sides of the separator are directly in contact with the diaphragm of the adjacent electrode assembly and form electrical insulation. At this time, two electrode assemblies each lead out two tabs, and the two electrode assemblies are connected in series through the tabs.

[0060] In one embodiment of the present invention, the outermost layer of at least one of the electrode assemblies comprises a separator, and the separator is adjacent to the separator; the outermost layer of at least one of the electrode assemblies comprises a current collector, and the current collector is adjacent to the other side of the separator.

[0061] In one embodiment of the present invention, the electrochemical device of the present invention comprises at least one separator, the separator is sealed and connected to the outer packaging, and independent sealed chambers are formed on both sides of the separator, each sealed chamber contains an electrode assembly and an electrolyte to form an electrochemical unit, wherein the separator has electronic conductivity, one side of the separator can be coated with an electrode active material, and the other side is in contact with the diaphragm of the electrode assembly to form electrical insulation. For example, the side of the separator close to the electrode assembly A is coated with a positive electrode active material, and the side close to the electrode assembly B is in contact with the diaphragm of the electrode assembly B to form electrical insulation with the electrode assembly B. At this time, two electrode assemblies each lead out two pole ears, and the separator leads out one pole ear, which is connected in parallel with the positive pole ear of the electrode assembly A, and then connected in series with the negative pole ear of the electrode assembly B.

[0062] In one embodiment of the present invention, the electrochemical device of the present invention comprises at least one separator, the separator is sealed and connected to the outer package, and independently sealed chambers are formed on both sides of the separator, each sealed chamber contains an electrode assembly and an electrolyte, forming an electrochemical unit, the separator has electronic insulation, one side of the separator is in contact with the diaphragm of the electrode assembly to form electrical insulation, and the other side of the separator is directly in contact with the current collector of the electrode assembly. At this time, the two electrode assemblies each lead out two pole ears, and the two electrode assemblies are connected in series through the pole ears.

[0063] In one embodiment of the present invention, the separator has electronic conductivity, the outermost layer of the electrode assembly comprises a current collector, the current collector is adjacent to the separator, and the current collectors of the electrode assemblies on both sides of the separator have opposite polarities.

[0064] In one embodiment of the present invention, the electrochemical device of the present invention comprises at least one separator, the separator has electronic conductivity, the separator is sealed and connected to the outer package, and independent sealed chambers are formed on both sides of the separator, each sealed chamber contains an electrode assembly and an electrolyte, forming an electrochemical unit, wherein one side of the separator is coated with an electrode active material, and the other side is directly in contact with and electrically connected to the current collector of the electrode assembly. For example, the side of the separator close to the electrode assembly A is coated with a positive electrode active material, and the side close to the electrode assembly B is directly in contact with and electrically connected to the negative electrode current collector of the electrode assembly B. At this time, the electrode assembly A can lead out a negative electrode tab, and the electrode assembly B can lead out a positive electrode tab, and the two electrochemical units are connected in series through the separator; or the electrode assemblies A and B each lead out two tabs, and the positive electrode tab of the electrode assembly A is connected in series with the negative electrode tab of the electrode assembly B. At this time, the two electrochemical units are connected in series through the separator and through the tabs. In addition, the separator can lead out a tab for monitoring the working state of the battery.

[0065] In one embodiment of the present invention, the separator has electronic insulation properties, and the outermost layer of the electrode assembly comprises a current collector, which is adjacent to the separator.

[0066] In one embodiment of the present invention, the electrochemical device of the present invention comprises at least one separator, the separator is sealed and connected to the outer package, and independent sealed chambers are formed on both sides of the separator, each sealed chamber contains an electrode assembly and an electrolyte to form an electrochemical unit, wherein the separator is an electronic insulator, and both sides of the separator are directly connected to the outermost current collector of the adjacent electrode assembly to form electrical insulation. At this time, two electrode assemblies each lead out two tabs, and the two electrode assemblies are connected in series through the tabs.

[0067] In one embodiment of the present invention, the separator has electronic conductivity, and a primer layer may be included between the separator and the electrode active material. The primer layer is used to improve the bonding performance between the separator and the active material, and to improve the electronic conductivity between the separator and the active material. The primer layer is usually obtained by coating a slurry formed by mixing conductive carbon black, styrene-butadiene rubber and deionized water on the separator and drying it. The primer layers on both sides of the separator may be the same or different.

[0068] The present invention also provides an electronic device, comprising any one of the above electrochemical devices.

[0069] The electrode assembly of the present invention is not particularly limited, and any electrode assembly of the prior art can be used as long as the purpose of the present invention can be achieved, for example, a laminated electrode assembly or a wound electrode assembly can be used. The electrode assembly generally includes a positive electrode sheet, a negative electrode sheet and a separator.

[0070] There is no particular limitation on the negative electrode plate in the present invention, as long as the purpose of the present invention can be achieved. For example, the negative electrode plate generally comprises a negative electrode current collector and a negative electrode active material layer. Among them, the negative electrode current collector is not particularly limited, and any negative electrode current collector known in the art can be used, such as copper foil, aluminum foil, aluminum alloy foil, and composite current collector. The negative electrode active material layer includes a negative electrode active material, and the negative electrode active material is not particularly limited, and any negative electrode active material known in the art can be used. For example, it can include at least one of artificial graphite, natural graphite, mesophase carbon microbeads, soft carbon, hard carbon, silicon, silicon carbon, lithium titanate, etc.

[0071] There is no particular limitation on the positive electrode sheet in the present invention, as long as the purpose of the present invention can be achieved. For example, the positive electrode sheet generally comprises a positive current collector and a positive active material. Among them, the positive current collector is not particularly limited, and can be any positive current collector known in the art, such as aluminum foil, aluminum alloy foil or composite current collector. The positive active material is not particularly limited, and can be any positive active material in the prior art, and the active material 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.

[0072] The electrolyte in the present invention is not particularly limited, and any electrolyte known in the art can be used, for example, it can be any one of a gel state, a solid state and a liquid state. For example, a liquid electrolyte can include a lithium salt and a non-aqueous solvent.

[0073] 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 invention can be achieved. For example, the lithium salt may include at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2), bistrifluoromethanesulfonyl imide lithium LiN(CF3SO2)2 (LiTFSI), bis(fluorosulfonyl)imide lithium Li(N(SO2F)2)(LiFSI), lithium bis(oxalate borate) LiB(C2O4)2 (LiBOB) or lithium difluorooxalate borate LiBF2(C2O4) (LiDFOB). For example, the lithium salt may be selected from LiPF6.

[0074] The non-aqueous solvent is not particularly limited as long as the purpose of the present invention 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.

[0075] For example, the carbonate compound may include at least one of diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), ethyl methyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), 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.

[0076] The separator in the present invention is not particularly limited, and for example, the separator includes a polymer or an inorganic substance formed of a material that is stable to the electrolyte of the present invention. The separator should generally have ion conductivity and electronic insulation.

[0077] For example, the diaphragm may include a substrate layer and a surface treatment layer. The substrate layer may be a nonwoven fabric, a film or a composite film having a porous structure, and the material of the substrate layer may be selected from at least one of polyethylene, polypropylene, polyethylene terephthalate and polyimide. Optionally, a polypropylene porous film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric or a polypropylene-polyethylene-polypropylene porous composite film may be used. Optionally, a surface treatment layer is provided on at least one surface of the substrate layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by a mixed polymer and an inorganic substance.

[0078] For example, the inorganic layer includes inorganic particles and a binder, and the inorganic particles are not particularly limited, for example, they can be selected from at least one of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and barium sulfate. The binder is not particularly limited, for example, it can be selected from one or more combinations of polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylic acid salt, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene. The polymer layer contains a polymer, and the material of the polymer includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylic acid salt, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly (vinylidene fluoride-hexafluoropropylene).

[0079] The present invention also provides a method for preparing a separator, which can be used to prepare the separator in which the encapsulation layer is completely coated with the intermediate layer, comprising the following steps:

[0080] (1) uniformly dispersing the encapsulation layer material in a dispersant to prepare an encapsulation layer suspension;

[0081] (2) using a casting device to cast the obtained suspension on both sides of the middle layer to prepare an encapsulation layer;

[0082] (3) Drying the dispersant in the encapsulation layer suspension to complete the preparation of the separator.

[0083] The present invention also provides a method for preparing a separator, which can be used to prepare the separator in which the encapsulation layer is completely coated with the intermediate layer, comprising the following steps:

[0084] (1) uniformly dispersing the encapsulation layer material in a dispersant to prepare an encapsulation layer suspension;

[0085] (2) uniformly dispersing the material in the middle layer into a dispersant to prepare an middle layer suspension;

[0086] (3) using a casting device to simultaneously cast the suspensions of the middle layer and the encapsulation layers on both sides;

[0087] (4) Drying the dispersant in the encapsulation layer and the intermediate layer suspension to complete the preparation of the separator.

[0088] The present invention also provides a method for preparing a separator, which can be used to prepare the separator with the intermediate layer coated around the encapsulation layer, comprising the following steps:

[0089] (1) uniformly dispersing the encapsulation layer material in a dispersant to prepare an encapsulation layer suspension;

[0090] (2) using a glue coating machine, preparing encapsulation layers on both sides of the middle layer;

[0091] (3) Drying the dispersant in the encapsulation layer suspension to complete the preparation of the separator.

[0092] The present invention also provides a method for preparing a separator, which can be used to prepare the separator with the intermediate layer coated around the encapsulation layer, comprising the following steps:

[0093] (1) uniformly dispersing the encapsulation layer material in a dispersant to prepare an encapsulation layer suspension;

[0094] (2) using a 3D printer to prepare encapsulation layers on both sides of the middle layer;

[0095] (3) Drying the dispersant in the encapsulation layer suspension to complete the preparation of the separator.

[0096] The present invention has no particular limitation on the dispersant, which may be a polar organic solvent commonly used in the art, such as NMP (N-methylpyrrolidone), DMF (N,N-dimethylformamide), THF (tetrahydrofuran), and the like.

[0097] The embodiments of the present invention will be described in more detail below with reference to Examples and Comparative Examples. Various tests and evaluations were performed according to the following methods, and "parts" and "%" are by weight unless otherwise specified.

[0098] Example

[0099] Preparation Example 1: Preparation of negative electrode sheet

[0100] The negative electrode active material graphite, conductive carbon black, and styrene-butadiene rubber are mixed in a mass ratio of 96:1.5:2.5, and deionized water is added as a solvent to prepare a slurry with a solid content of 70%, and stirred evenly. The slurry is evenly coated on one surface of a copper foil with a thickness of 10 μm, and dried at 110°C to obtain a negative electrode sheet with a single-sided coating of a negative electrode active material layer with a coating thickness of 150 μm, and then the above coating steps are repeated on the other surface of the negative electrode sheet. After coating, the sheet is cut into a specification of 41 mm × 61 mm and welded to the pole ear for standby use.

[0101] Preparation Example 2: Preparation of positive electrode sheet

[0102] The positive electrode active material LiCoO2, conductive carbon black, and PVDF (polyvinylidene fluoride) are mixed in a mass ratio of 97.5:1.0:1.5, and NMP is added as a solvent to prepare a slurry with a solid content of 75%, and stirred evenly. The slurry is evenly coated on one surface of an aluminum foil with a thickness of 12μm, and dried at 90°C to obtain a positive electrode sheet with a single-sided coating of a positive electrode active material layer with a coating thickness of 100μm. Then repeat the above steps on the other surface of the positive electrode sheet. After coating, the sheet is cut into a specification of 38mm×58mm and welded to the pole ear for standby use.

[0103] Preparation Example 3: Preparation of electrolyte

[0104] In a dry argon atmosphere, organic solvents EC (ethylene carbonate), EMC (ethyl methyl carbonate) and DEC (diethyl carbonate) are first mixed in a mass ratio of EC:EMC:DEC=30:50:20, and then LiPF6 (lithium hexafluorophosphate) is added to the organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1.15M.

[0105] Preparation Example 4: Preparation of electrode assembly

[0106] A PE (polyethylene) film with a thickness of 15 μm is selected as an isolation membrane. A positive electrode sheet of Preparation Example 2 is placed on both sides of the negative electrode sheet of Preparation Example 1, and a layer of isolation membrane is placed between the positive electrode sheet and the negative electrode sheet to form a stack. Then, the four corners of the entire stack structure are fixed, and the positive electrode tab and the negative electrode tab are led out to obtain electrode assembly A.

[0107] A PE film with a thickness of 15 μm is selected as the isolation film. A negative electrode sheet is placed on each side of the positive electrode sheet, and a layer of isolation film is placed between the positive electrode sheet and the negative electrode sheet to form a stack. Then, the four corners of the entire stack structure are fixed, and the positive electrode tab and the negative electrode tab are led out to obtain electrode assembly B.

[0108] Example 1

[0109] Preparation of separator

[0110] (1) uniformly dispersing the encapsulating material PP in the encapsulating layer into the dispersant NMP (N-methylpyrrolidone) to obtain an encapsulating layer suspension, wherein the concentration of the suspension is 45 wt %;

[0111] (2) Using a glue coating machine, a 40 μm thick encapsulation layer PP is prepared on the edges of both surfaces of a 20 μm thick intermediate layer PET (polyethylene terephthalate) film. The width of the encapsulation layer PP is 5 mm. The softening temperature of the intermediate layer PET is 270°C, the softening temperature of the encapsulation layer PP is 150°C, and the compression rate of the encapsulation layer thickness is 70%.

[0112] (3) The dispersant NMP in the encapsulation layer suspension is dried at 130°C to complete the preparation of the separator.

[0113] The compression rate of the packaging layer thickness of each embodiment is adjusted by adjusting parameters such as packaging time, packaging pressure, and packaging temperature. See Table 1 for details.

[0114] Assembly of electrode assembly

[0115] Place the punched packaging film (aluminum-plastic film) with a thickness of 90 μm in the assembly fixture with the pit side facing up, then place the electrode assembly A of Preparation Example 4 in the pit, and then place the separator on the electrode assembly A, with one side of the separator in contact with the separator of the electrode assembly A, and apply external force to press it tightly.

[0116] The semi-finished assembly is placed in another assembly fixture, and the electrode assembly B of Preparation Example 4 is placed on the separator, with the other side of the separator in contact with the separator of the electrode assembly B, and then another aluminum-plastic film with a thickness of 90 μm formed by punching is covered on the electrode assembly B with the pit surface facing downward, and then the two aluminum-plastic films and the separator are heat-sealed together by hot pressing, so that the electrode assembly A and the electrode assembly B are separated by the separator to obtain an assembled electrode assembly. The assembled electrode assembly has two independent cavities, wherein the electrode assembly A corresponds to the first cavity and the electrode assembly B corresponds to the second cavity.

[0117] Electrode assembly injection packaging

[0118] The electrolyte of Preparation Example 3 is injected into the two cavities of the above-mentioned assembled electrode assembly respectively and then packaged. The tabs of the two electrode assemblies are led out of the outer packaging, and the positive tab of electrode assembly A and the negative tab of electrode assembly B are welded together to achieve series conduction between the two electrode assemblies.

[0119] Example 2

[0120] Except that the compression rate of the encapsulation layer thickness during the preparation of the separator is 40%, the rest is the same as Example 1.

[0121] Example 3

[0122] Except that the compression rate of the encapsulation layer thickness during the preparation of the separator is 20%, the rest is the same as Example 1.

[0123] Example 4

[0124] The preparation process of the partition is the same as Example 1 except that PP is used as the encapsulation layer material, PP is used as the intermediate layer material, the softening temperature of the encapsulation layer is 130°C, the softening temperature of the intermediate layer is 150°C, and the compression rate of the encapsulation layer thickness is 40%.

[0125] Example 5

[0126] The process of preparing the partition is the same as Example 1 except that PI (polyimide) is used as the material of the intermediate layer, the temperature at which the intermediate layer starts to soften is 334° C., and the compression rate of the packaging layer thickness is 40%.

[0127] Example 6

[0128] The preparation process of the partition is the same as Example 1 except that the packaging layer material is PS (polystyrene), the middle layer material is stainless steel, the softening temperature of the packaging layer is 240°C, the softening temperature of the middle layer is 1440°C, and the compression rate of the packaging layer thickness is 40%.

[0129] Example 7

[0130] Except that in the preparation process of the partition, PI is used as the middle layer material, the temperature at which the middle layer begins to soften is 334°C, the compression rate of the encapsulation layer thickness is 40%, the interface adhesion between the encapsulation layer and the middle layer is 28N / m, and the interface adhesion between the encapsulation layer and the outer packaging is 17.3N / m, the rest is the same as Example 1.

[0131] Example 8

[0132] Except that in the preparation process of the partition, the encapsulation layer material is PS, the intermediate layer material is PI, the temperature at which the encapsulation layer begins to soften is 240°C, the temperature at which the intermediate layer material begins to soften is 334°C, and the compression rate of the encapsulation layer thickness is 40%, the rest is the same as Example 1.

[0133] Example 9

[0134] Except that in the preparation process of the separator, PI is used as the intermediate layer material, the temperature at which the intermediate layer material begins to soften is 334° C., and the ratio A is 0, the rest is the same as Example 1.

[0135] Example 10

[0136] Except that in the preparation process of the separator, PI is used as the intermediate layer material, the temperature at which the intermediate layer material begins to soften is 334° C., and the ratio A is 0.1, the rest is the same as Example 1.

[0137] Embodiment 11

[0138] Except that in the preparation process of the partition, PI is used as the intermediate layer material, the temperature at which the intermediate layer material begins to soften is 334° C., the compression rate of the packaging layer thickness is 40%, and the ratio A is 1.5, the rest is the same as Example 1.

[0139] Example 12

[0140] Except that in the preparation process of the partition, PI is used as the intermediate layer material, the temperature at which the intermediate layer material begins to soften is 334° C., the compression rate of the packaging layer thickness is 20%, and the ratio A is 20, the rest is the same as Example 1.

[0141] In Examples 9-12, the ratio A is adjusted by adjusting the glue coating width of the encapsulation glue coating area. The smaller the glue coating width, the smaller the A value.

[0142] Embodiment 13

[0143] Except that during the preparation of the partition, Al is used as the intermediate layer material, the temperature at which the packaging layer material begins to soften is 130°C, the temperature at which the intermediate layer material begins to soften is 660°C, and the compression rate of the packaging layer thickness is 40%, the rest is the same as Example 1.

[0144] Embodiment 14

[0145] Except that in the preparation process of the partition, the intermediate layer material uses a carbon film, the temperature at which the intermediate layer begins to soften is 3500° C., and the compression rate of the packaging layer thickness is 40%, the rest is the same as Example 1.

[0146] Embodiment 15

[0147] Except that in the preparation process of the partition, PI is used as the intermediate layer material, the softening temperature of the intermediate layer material is 334°C, the compression rate of the packaging layer thickness is 40%, and the intermediate layer thickness is 1000μm, the rest is the same as Example 1.

[0148] Example 16

[0149] Except that in the preparation process of the partition, PI is used as the intermediate layer material, the temperature at which the intermediate layer material begins to soften is 334°C, the compression rate of the packaging layer thickness is 40%, and the intermediate layer thickness is 10μm, the rest is the same as Example 1.

[0150] Embodiment 17

[0151] The preparation of the partition is the same as Example 1 except that: PI is used as the intermediate layer material, the temperature at which the intermediate layer material starts to soften is 334°C, the compression rate of the encapsulation layer thickness is 40%, and the intermediate layer thickness is 2 μm.

[0152] Embodiment 18

[0153] In addition to the preparation of the partition: the middle layer material uses PI, the temperature at which the middle layer material begins to soften is 334°C, and the compression rate of the encapsulation layer thickness is 40%;

[0154] Assembly of electrode assembly:

[0155] Place the punched packaging film (aluminum-plastic film) with a thickness of 90 μm in the assembly fixture with the pit side facing up, then place the electrode assembly A of Preparation Example 4 in the pit, and then place the separator on the electrode assembly A, with one side of the separator in contact with the separator of the electrode assembly A, and apply external force to press it tightly.

[0156] The semi-finished assembly is placed in another assembly fixture, and the electrode assembly B of Preparation Example 4 is placed on the separator, with the other side of the separator in contact with the current collector of the electrode assembly B, and then another aluminum-plastic film with a thickness of 90 μm formed by punching is covered on the electrode assembly B with the pit surface facing downward, and then the two aluminum-plastic films and the separator are heat-sealed together by hot pressing, so that the electrode assembly A and the electrode assembly B are separated by the separator to obtain an assembled electrode assembly. The assembled electrode assembly has two independent cavities, wherein the electrode assembly A corresponds to the first cavity and the electrode assembly B corresponds to the second cavity.

[0157] The rest is the same as Example 1.

[0158] Embodiment 19

[0159] In addition to the preparation process of the partition, the material of the middle layer is stainless steel, the melting point of the middle layer is 1440°C, and the compression rate of the encapsulation layer thickness is 40%;

[0160] Assembly of electrode assembly:

[0161] Place the punched packaging film (aluminum-plastic film) with a thickness of 90 μm in the assembly fixture with the pit side facing up, and then place the electrode assembly A of Preparation Example 4 in the pit with the positive electrode sheet of electrode assembly A facing up. Place a partition on the electrode assembly A with one side of the partition in contact with the positive electrode current collector of electrode assembly A, and apply external force to compress it.

[0162] The semi-finished assembly is placed in an assembly fixture with the separator facing upward, and the electrode assembly B of Preparation Example 4 is placed on the separator with the negative electrode facing downward, and the other side of the separator is in contact with the negative electrode current collector of the electrode assembly B, and then another aluminum-plastic film with a thickness of 90 μm formed by punching is covered on the electrode assembly B with the pit surface facing downward, and then the two aluminum-plastic films and the separator are heat-sealed together by hot pressing, so that the electrode assembly A and the electrode assembly B are separated by the separator to obtain an assembled electrode assembly. The assembled electrode assembly has two independent cavities, wherein the electrode assembly A corresponds to the first cavity and the electrode assembly B corresponds to the second cavity.

[0163] Electrode assembly injection packaging:

[0164] The electrolyte of Preparation Example 3 is respectively injected into the two cavities of the assembled electrode assembly and then packaged. The tabs of the electrode assemblies A and B are led out of the outer packaging, and the two electrochemical units are connected in series through the separator to obtain a lithium-ion battery.

[0165] The rest is the same as Example 1.

[0166] Embodiment 20

[0167] In addition to the preparation of the separator: the middle layer material is PI, the temperature at which the middle layer material begins to soften is 334°C, and the compression rate of the encapsulation layer thickness is 40%;

[0168] Assembly of electrode assembly:

[0169] Place the punched packaging film (aluminum-plastic film) with a thickness of 90 μm in the assembly fixture with the pit side facing up, then place the electrode assembly A of Preparation Example 4 in the pit, and then place the separator on the electrode assembly A, with one side of the separator in contact with the current collector of the electrode assembly A, and apply external force to press it tightly.

[0170] The semi-finished assembly is placed in another assembly fixture, and the electrode assembly B of Preparation Example 4 is placed on the separator, with the other side of the separator in contact with the current collector of the electrode assembly B, and then another aluminum-plastic film with a thickness of 90 μm formed by punching is covered on the electrode assembly B with the pit surface facing downward, and then the two aluminum-plastic films and the separator are heat-sealed together by hot pressing, so that the electrode assembly A and the electrode assembly B are separated by the separator to obtain an assembled electrode assembly. The assembled electrode assembly has two independent cavities, wherein the electrode assembly A corresponds to the first cavity and the electrode assembly B corresponds to the second cavity.

[0171] The rest is the same as Example 1.

[0172] Embodiment 21

[0173] In addition to the preparation of the partition: the middle layer material is PI, the temperature at which the middle layer material begins to soften is 334°C, the compression rate of the encapsulation layer thickness is 40%, and both sides of the middle layer are coated with PP.

[0174] The preparation steps of the separator are:

[0175] (1) uniformly dispersing the encapsulating material PP in the encapsulating layer into the dispersant NMP (N-methylpyrrolidone) to prepare an encapsulating layer suspension, wherein the concentration of the suspension is 45 wt %;

[0176] (2) Using a glue coating machine, a 30 μm thick encapsulation layer PP is evenly prepared on both sides of a 20 μm thick intermediate layer PI (polyimide) film. The intermediate layer PI begins to soften at 334°C, and the encapsulation layer PP begins to soften at 150°C.

[0177] (3) The dispersant NMP in the encapsulation layer suspension is dried at 130°C to complete the preparation of the separator.

[0178] The rest is the same as Example 1.

[0179] Embodiment 22

[0180] In addition to the preparation of the partition: the middle layer material is PI, the temperature at which the middle layer material begins to soften is 334°C, the compression rate of the encapsulation layer thickness is 40%, and both sides of the middle layer are coated with PP.

[0181] The preparation steps of the separator are:

[0182] (1) uniformly dispersing the encapsulating material PP in the encapsulating layer into the dispersant NMP (N-methylpyrrolidone) to prepare an encapsulating layer suspension, wherein the concentration of the suspension is 45 wt %;

[0183] (2) Using a glue coating machine, a 30 μm thick encapsulation layer PP is evenly prepared on both sides of a 20 μm thick intermediate layer PI (polyimide) film. The intermediate layer PI begins to soften at 334°C, and the encapsulation layer PP begins to soften at 150°C.

[0184] (3) The dispersant NMP in the encapsulation layer suspension is dried at 130°C to complete the preparation of the separator.

[0185] Assembly of electrode assembly:

[0186] Place the punched packaging film (aluminum-plastic film) with a thickness of 90 μm in the assembly fixture with the pit side facing up, then place the electrode assembly A of Preparation Example 4 in the pit, and then place the separator on the electrode assembly A, with one side of the separator in contact with the separator of the electrode assembly A, and apply external force to press it tightly.

[0187] The semi-finished assembly is placed in another assembly fixture, and the electrode assembly B of Preparation Example 4 is placed on the separator, with the other side of the separator in contact with the current collector of the electrode assembly B, and then another aluminum-plastic film with a thickness of 90 μm formed by punching is covered on the electrode assembly B with the pit surface facing downward, and then the two aluminum-plastic films and the separator are heat-sealed together by hot pressing, so that the electrode assembly A and the electrode assembly B are separated by the separator to obtain an assembled electrode assembly. The assembled electrode assembly has two independent cavities, wherein the electrode assembly A corresponds to the first cavity and the electrode assembly B corresponds to the second cavity.

[0188] The rest is the same as Example 1.

[0189] Embodiment 23

[0190] In addition to the preparation of the partition: the middle layer material is PI, the temperature at which the middle layer material begins to soften is 334°C, the compression rate of the encapsulation layer thickness is 40%, and both sides of the middle layer are coated with PP.

[0191] The preparation steps of the separator are:

[0192] (1) uniformly dispersing the encapsulating material PP in the encapsulating layer into the dispersant NMP (N-methylpyrrolidone) to prepare an encapsulating layer suspension, wherein the concentration of the suspension is 45 wt %;

[0193] (2) Using a glue coating machine, a 30 μm thick encapsulation layer PP is evenly prepared on both sides of a 20 μm thick intermediate layer PI (polyimide) film. The intermediate layer PI begins to soften at 334°C, and the encapsulation layer PP begins to soften at 150°C.

[0194] (3) The dispersant NMP in the encapsulation layer suspension is dried at 130°C to complete the preparation of the separator.

[0195] Assembly of electrode assembly:

[0196] Place the punched packaging film (aluminum-plastic film) with a thickness of 90 μm in the assembly fixture with the pit side facing up, then place the electrode assembly A of Preparation Example 4 in the pit, and then place the separator on the electrode assembly A, with one side of the separator in contact with the current collector of the electrode assembly A, and apply external force to press it tightly.

[0197] The semi-finished assembly is placed in another assembly fixture, the electrode assembly B of Preparation Example 4 is placed on the separator, and then another aluminum-plastic film with a thickness of 90 μm formed by punching is covered on the electrode assembly B with the pit surface facing downward, and the other side of the separator is in contact with the current collector of the electrode assembly B, and then the two aluminum-plastic films and the separator are heat-sealed together by hot pressing, so that the electrode assembly A and the electrode assembly B are separated by the separator to obtain an assembled electrode assembly. The assembled electrode assembly has two independent cavities, wherein the electrode assembly A corresponds to the first cavity and the electrode assembly B corresponds to the second cavity.

[0198] The rest is the same as Example 1.

[0199] Embodiment 24

[0200] In addition to the preparation of the separator: the middle layer is stainless steel with a melting point of 1440°C and a compression rate of 40% for the thickness of the encapsulation layer.

[0201] Assembly of electrode assembly:

[0202] Place the punched packaging film (aluminum-plastic film) with a thickness of 90 μm in the assembly fixture with the pit side facing up, then place the electrode assembly A of Preparation Example 4 in the pit, and then place the separator on the electrode assembly A, with one side of the separator in contact with the separator of the electrode assembly A, and apply external force to press it tightly.

[0203] The semi-finished assembly is placed in another assembly fixture, and the electrode assembly B of Preparation Example 4 is placed on the separator, with the other side of the separator in contact with the positive current collector of the electrode assembly B, and then another aluminum-plastic film with a thickness of 90 μm formed by punching is covered on the electrode assembly B with the pit surface facing downward, and then the two aluminum-plastic films and the separator are heat-sealed together by hot pressing, so that the electrode assembly A and the electrode assembly B are separated by the separator to obtain an assembled electrode assembly. The assembled electrode assembly has two independent cavities, wherein the electrode assembly A corresponds to the first cavity and the electrode assembly B corresponds to the second cavity.

[0204] Electrode assembly injection packaging:

[0205] The electrolyte of Preparation Example 3 was respectively injected into the two cavities of the assembled electrode assembly and then packaged. The tabs of the two electrode assemblies were led out of the outer packaging, and the positive tab of electrode assembly A was welded with the negative tab of electrode assembly B to achieve series conduction between the two electrode assemblies. The tab of the separator was connected in parallel with the positive tab of electrode assembly A, and then connected in series with the negative tab of electrode assembly B to obtain a lithium-ion battery.

[0206] The rest is the same as Example 1.

[0207] Embodiment 25

[0208] In addition to the preparation of the separator: the compression rate of the encapsulation layer thickness is 40%;

[0209] Preparation of electrode assembly:

[0210] The double-sided coated negative electrode sheet, the first separator, the double-sided coated positive electrode sheet, and the second separator are stacked in sequence to form a laminate, and then the entire laminate is wound, the positive electrode tab and the negative electrode tab are led out, and the first separator is placed on the outermost side. Among them, the separator uses a polyethylene (PE) film with a thickness of 15 μm, the negative electrode sheet is prepared by Preparation Example 1, and the positive electrode sheet is prepared by Preparation Example 2. Electrode assembly A is prepared.

[0211] The double-sided coated negative electrode sheet, the first separator, the double-sided coated positive electrode sheet, and the second separator are sequentially stacked to form a laminate, and then the entire laminate is wound, the positive electrode tab and the negative electrode tab are led out, and the second separator is placed on the outermost side. The negative electrode sheet is prepared by Preparation Example 1, and the positive electrode sheet is prepared by Preparation Example 2. Among them, the separator is a polyethylene (PE) film with a thickness of 15 μm. Electrode assembly B is prepared.

[0212] The rest is the same as Example 1.

[0213] Embodiment 26

[0214] In addition to the preparation of the separator: the intermediate layer material is stainless steel with a melting point of 1440°C, and the compression rate of the encapsulation layer thickness is 40%;

[0215] Preparation of electrode assembly:

[0216] The double-sided coated negative electrode sheet, the first separator, the double-sided coated positive electrode sheet, and the second separator are stacked in sequence to form a laminate, and then the entire laminate is wound, the positive electrode tab and the negative electrode tab are led out, and the first separator is placed on the outermost side. Among them, the separator uses a polyethylene (PE) film with a thickness of 15 μm, the negative electrode sheet is prepared by Preparation Example 1, and the positive electrode sheet is prepared by Preparation Example 2. Electrode assembly A is prepared.

[0217] The double-sided coated negative electrode sheet, the first separator, the double-sided coated positive electrode sheet, and the second separator are stacked in sequence to form a laminate, and then the entire laminate is wound, the positive electrode tab and the negative electrode tab are led out, and the positive electrode current collector of the positive electrode sheet is placed on the outermost side. Among them, the separator uses a polyethylene (PE) film with a thickness of 15 μm, the negative electrode sheet is prepared by Preparation Example 1, and the positive electrode sheet is prepared by Preparation Example 2. Electrode assembly B is prepared.

[0218] Assembly of electrode assembly:

[0219] Place the punched packaging film (aluminum-plastic film) with a thickness of 90 μm in an assembly fixture with the pit side facing upward, then place the above-mentioned electrode assembly A in the pit, and then place the partition on the electrode assembly A, with one side of the partition in contact with the first diaphragm of the electrode assembly A, and apply external force to press it tightly.

[0220] The semi-finished assembly is placed in another assembly fixture, the electrode assembly B is placed on the separator, the other side of the separator is in contact with the positive current collector of the electrode assembly B, and then another aluminum-plastic film with a thickness of 90 μm is punched and formed with the pit surface facing downward and covered on the electrode assembly B, and then the two aluminum-plastic films and the separator are heat-sealed together by hot pressing, so that the electrode assembly A and the electrode assembly B are separated by the separator to obtain an assembled electrode assembly. The assembled electrode assembly has two independent cavities, wherein the electrode assembly A corresponds to the first cavity and the electrode assembly B corresponds to the second cavity.

[0221] Electrode assembly injection packaging:

[0222] The electrolyte of Preparation Example 3 is injected into the two cavities of the assembled electrode assembly respectively and then packaged. The tabs of the two electrode assemblies are led out of the outer packaging, and the positive tab of electrode assembly A and the negative tab of electrode assembly B are welded together to achieve series conduction between the two electrode assemblies.

[0223] The rest is the same as Example 1.

[0224] Embodiment 27

[0225] In addition to the preparation of the separator: the intermediate layer material is stainless steel with a melting point of 1440°C, and the compression rate of the encapsulation layer thickness is 40%;

[0226] Preparation of electrode assembly:

[0227] The double-sided coated negative electrode sheet, the separator, and the double-sided coated positive electrode sheet are stacked in sequence to form a laminate, and then the entire laminate is wound, the positive electrode tab and the negative electrode tab are led out, and the negative electrode collector of the negative electrode sheet is placed on the outermost side. Among them, the separator uses a polyethylene (PE) film with a thickness of 15 μm, the negative electrode sheet is prepared by Preparation Example 1, and the positive electrode sheet is prepared by Preparation Example 2. Electrode assembly A is prepared.

[0228] The double-sided coated negative electrode sheet, the separator, and the double-sided coated positive electrode sheet are stacked in sequence to form a laminate, and then the entire laminate is wound, the positive electrode tab and the negative electrode tab are led out, and the positive electrode collector of the positive electrode sheet is placed on the outermost side. Among them, the separator uses a polyethylene (PE) film with a thickness of 15 μm, the negative electrode sheet is prepared by Preparation Example 1, and the positive electrode sheet is prepared by Preparation Example 2. Electrode assembly B is prepared.

[0229] Assembly of electrode assembly:

[0230] Place the punched packaging film (aluminum-plastic film) with a thickness of 90 μm in the assembly fixture with the pit side facing upward, and then place the above-mentioned electrode assembly A in the pit with the positive electrode plate of the electrode assembly A facing upward, place the separator on the electrode assembly A, and make one side of the separator contact with the negative electrode collector of the electrode assembly A, and apply external force to press it tightly.

[0231] The semi-finished assembly is placed in another assembly fixture, with the separator facing upward, and the electrode assembly B is placed on the separator with the negative electrode facing downward, and the other side of the separator is in contact with the positive electrode current collector of the electrode assembly B, and then another aluminum-plastic film with a thickness of 90 μm formed by punching is covered on the electrode assembly B with the pit surface facing downward, and then the two aluminum-plastic films and the separator are heat-sealed together by hot pressing, so that the electrode assembly A and the electrode assembly B are separated by the separator to obtain an assembled electrode assembly. The assembled electrode assembly has two independent cavities, wherein the electrode assembly A corresponds to the first cavity and the electrode assembly B corresponds to the second cavity.

[0232] Electrode assembly injection packaging:

[0233] The electrolyte of Preparation Example 3 is respectively injected into the two cavities of the assembled electrode assembly and then packaged. The tabs of the electrode assemblies A and B are led out of the outer packaging, and the two electrochemical units are connected in series through the separator to obtain a lithium-ion battery.

[0234] The rest is the same as Example 1.

[0235] Comparative Example 1

[0236] Single-electrode lithium-ion battery

[0237] The positive electrode sheet of Preparation Example 2 and the negative electrode sheet of Preparation Example 1 were stacked together, with a PE separator of 15 μm thickness between the positive electrode sheet and the negative electrode sheet, and were packaged with aluminum foil, and the electrolyte of Preparation Example 3 was injected, and the tabs of the positive and negative electrode sheets were led out of the outer packaging to obtain a lithium-ion battery.

[0238] Comparative Example 2

[0239] Two independent electrode assemblies are externally connected in series, such as Figure 5 As shown,

[0240] Electrode assembly injection packaging:

[0241] The four corners of the electrode assemblies A and B of Preparation Example 4 were fixed respectively, and the packages were packaged with aluminum-plastic film, and then the packages were sealed on all sides; the electrolyte of Preparation Example 3 was injected into the aluminum-plastic film respectively, and all the tabs of the electrode assemblies A and B were led out of the aluminum-plastic film. The positive tab of the electrode assembly A and the negative tab of the electrode assembly B were welded together by laser welding to achieve series conduction between the electrode assemblies A and B, and the battery assembly was completed.

[0242] Comparative Example 3

[0243] Two independent electrode assemblies are connected in series head to tail, such as Figure 6 As shown,

[0244] Electrode assembly and liquid injection packaging:

[0245] Coat the positive electrode tab of the electrode assembly in Preparation Example 4 with sealant, weld the negative electrode of electrode assembly A to the positive electrode tab of electrode assembly B, realize the series connection of the electrodes of electrode assembly A and electrode assembly B, and seal the electrode assembly after the series connection in a formed aluminum-plastic film. During packaging, in addition to the sealing of the top side of the outer contour, each electrode assembly is sealed and packaged along the positive electrode sealant in the width direction of the electrode assembly to achieve the isolation of the cavity between each electrode assembly, and the electrolyte of Preparation Example 3 is respectively injected into the cavity where the two electrode assemblies are located. After packaging, the positive electrode tab is led out on one side of the length direction of the electrode assembly, and the negative electrode tab is led out on one side, and the remaining series tabs are all in the outer packaging of the electrode assembly.

[0246] Comparative Example 4

[0247] Two independent electrode assemblies are connected in series, such as Figure 7 As shown,

[0248] Assembly of electrode assembly:

[0249] Place the electrode assembly A of Preparation Example 4 on one side of the formed aluminum-plastic film, cover it with the upper aluminum-plastic film, and press the side with the electrode assembly A; apply glue on the boundary position of the aluminum-plastic film where the electrode assembly A has been placed, press the upper and lower aluminum-plastic films, and apply glue along the length direction of the electrode assembly from the tail of the electrode assembly to the top packaging area, and solidify it into shape.

[0250] In the semi-finished product, the electrode assembly B of Preparation Example 4 is placed in the empty area on the side of the electrode assembly A, and the entire aluminum-plastic film is top-sealed. The top sealing intersects the glue-coated area vertically, and the contact sealing is performed, so that the electrode assemblies A and B are respectively in independent sealed cavities.

[0251] Electrode assembly injection packaging

[0252] The electrolyte of Preparation Example 3 was injected into the cavities where the two electrode assemblies were located, and the aluminum-plastic film was sealed. The tabs of the two electrode assemblies were led out of the outer packaging, and the positive tab of electrode assembly A was welded to the negative tab of electrode assembly B. It was ensured that the two electrode assemblies were in two independent sealed cavities, and the electrolyte could not be exchanged.

[0253] Comparative Example 5

[0254] Single bag thickness stacking without partitions

[0255] Assembly of electrode assembly:

[0256] The packaging film with a punched hole, which is an aluminum-plastic film with a thickness of 90 μm, is placed in an assembly fixture with the hole facing upward, and then the electrode assembly A of Preparation Example 4 is placed in the hole, and the electrode assembly B of Preparation Example 4 is placed on the electrode assembly A. The electrode assembly A and the electrode assembly B are separated by a diaphragm and pressed tightly. Then another piece of packaging film is covered on the electrode assembly B with the hole facing downward, and heat-sealed around.

[0257] Electrode assembly injection packaging:

[0258] The electrolyte of Preparation Example 3 is injected into the cavity where the two electrode assemblies are located. After the injection, the four sides are packaged. The positive and negative tabs of the electrode assembly are led out of the outer packaging, and the tabs are staggered to avoid stacking in the thickness direction of the tabs, which may cause sealing failure.

[0259] The positive electrode tab of electrode assembly A and the negative electrode tab of electrode assembly B are welded together to achieve series conduction between the two electrode assemblies.

[0260] Comparative Example 6

[0261] The separator uses a common single-layer PP separator directly as a separator, with a thickness of 20μm and a softening temperature of 165℃;

[0262] Assembly of electrode assembly:

[0263] Place the punched packaging film (aluminum-plastic film) with a thickness of 90 μm in an assembly fixture with the pit side facing upward, then place the electrode assembly A of Preparation Example 4 in the pit, and then place the PP diaphragm on the electrode assembly A and apply external force to compress it.

[0264] The semi-finished assembly is placed in another assembly fixture, the electrode assembly B of Preparation Example 4 is placed on the PP diaphragm, and then another aluminum-plastic film with a thickness of 90 μm formed by punching is covered on the electrode assembly B with the pit surface facing downward, and then the two aluminum-plastic films and the PP diaphragm are heat-sealed together by hot pressing, so that the electrode assembly A and the electrode assembly B are separated by the PP diaphragm to obtain an assembled electrode assembly. The assembled electrode assembly has two independent cavities, wherein the electrode assembly A corresponds to the first cavity and the electrode assembly B corresponds to the second cavity.

[0265] Electrode assembly injection packaging

[0266] The electrolyte of Preparation Example 3 is injected into the cavity where the two electrode assemblies are located. After the injection, the four sides are packaged. The positive and negative tabs of the electrode assemblies are led out of the outer packaging. The positive tab of electrode assembly A and the negative tab of electrode assembly B are welded together to achieve series conduction between the two electrode assemblies.

[0267] Comparative Example 7

[0268] The process is the same as that of Comparative Example 6 except that a single layer of PP is used as the separator, the thickness of the separator is 20 μm, and the softening start temperature is 165° C.

[0269] Comparative Example 8

[0270] The process is the same as Comparative Example 6 except that a single-layer PI is used as the separator, the thickness of the separator is 20 μm, and the softening start temperature is 334° C.

[0271] Comparative Example 9

[0272] The process is the same as that of Comparative Example 6 except that a single layer of stainless steel is used as the separator, the thickness of the separator is 20 μm, and the melting point is 1440° C.

[0273] <Performance Test>

[0274] The separators for electrochemical devices and bipolar lithium-ion batteries prepared in the embodiments and comparative examples were tested using the following methods:

[0275] F1 test of the interface adhesion between the encapsulation layer and the intermediate layer

[0276] 1) removing the sealing area portion from the electrode assembly as sample 1;

[0277] 2) Cooling sample 1 in liquid nitrogen, and grinding off the outer packaging on one side of the encapsulation layer to expose the interface between the encapsulation layer and the middle layer;

[0278] 3) Cut sample 1 into test strips with a width of 8 mm and a length of 6 cm, ensuring that the encapsulation layer completely covers the middle layer in this area, to obtain sample 2;

[0279] 4) Paste high-adhesive and high-strength adhesive tape on the surface of the encapsulation layer of sample 2;

[0280] 5) Use a high-speed rail tensile testing machine to slowly tear off the high-viscosity and high-strength adhesive tape from the surface of sample 2 at an angle of 90°, so that the interface between the encapsulation layer and the intermediate layer is separated;

[0281] 6) Record the stable pulling force during the interface separation, and calculate the interface adhesion between the encapsulation layer and the intermediate layer based on this.

[0282] F2 test of the interface adhesion between the encapsulation layer and the outer packaging

[0283] 1) removing the sealing area portion from the electrode assembly as sample 1;

[0284] 2) Cooling sample 1 in liquid nitrogen, and grinding off the middle layer on one side of the encapsulation layer to expose the interface between the encapsulation layer and the outer package;

[0285] 3) Cut sample 1 into test strips with a width of 8 mm and a length of 6 cm, ensuring that the encapsulation layer completely covers the outer packaging in this area, to obtain sample 2;

[0286] 4) Paste high-adhesive and high-strength adhesive tape on the surface of the adhesive layer of sample 2;

[0287] 5) Use a high-speed rail tensile machine to slowly tear off the high-viscosity and high-strength adhesive tape from the surface of sample 2 at an angle of 90°, so that the interface between the encapsulation layer and the outer packaging is separated;

[0288] 6) Record the stable pulling force during the above interface separation, and calculate the interface adhesion force between the encapsulation layer and the outer packaging based on this.

[0289] Package strength test

[0290] 1) removing the sealing area portion from the electrode assembly as sample 1;

[0291] 2) Cut sample 1 into test strips with a width of 8 mm, ensuring that the entire sealed area is completely preserved and the outer packaging on both sides of the sealed area is intact, thereby obtaining sample 2;

[0292] 3) Use a high-speed rail tensile machine to tear open the outer packaging on both sides at an angle of 180° so that the two layers of outer packaging in the packaging area are separated from each other;

[0293] 4) Record the stable pulling force when the two layers of outer packaging are separated, and calculate the packaging strength based on this.

[0294] 1.5m drop test Package damage test

[0295] 1) Disassemble the electrode assembly sample after testing and remove the seal area separately for standby use;

[0296] 2) Add red medicine to the sealed area, and make sure that the red medicine is on the top and the sealed area is on the bottom. Let it stand for 12 hours.

[0297] 3) Then, the sealing area is destroyed through the packaging strength test to observe the penetration of mercurochrome into the sealing area;

[0298] 4) If the depth of the mercurochrome penetrating into the sealing area exceeds 1 / 2 of the width of the sealing area, it is determined that the sealing is damaged; otherwise, it is determined that the sealing is not damaged.

[0299] Discharge energy density ED test

[0300] The lithium-ion battery was left to stand at room temperature for 30 minutes, and then charged at a constant current of 0.05C charging rate to a voltage of 4.45V (rated voltage of Comparative Example 1) or 8.90V (rated voltage of other comparative examples and all embodiments), and then the electrochemical device was discharged at a rate of 0.05C to 3.00V (rated voltage of Comparative Example 1) or 6.00V (other comparative examples and all embodiments), and the above charge / discharge steps were repeated for 3 cycles to complete the formation of the electrochemical device to be tested. After the formation of the electrochemical device is completed, the constant current is charged at a charging rate of 0.1C to a voltage of 4.45V (rated voltage of Comparative Example 1) or 8.90V (other comparative examples and all embodiments), and then the electrochemical device is discharged at a discharge rate of 0.1C to 3.00V (rated voltage of Comparative Example 1) or 6.00V (other comparative examples and all embodiments), and its discharge capacity is recorded, and then its energy density at 0.1C discharge is calculated:

[0301] Energy density (Wh / L) = discharge capacity (Wh) / lithium-ion battery volume size (L)

[0302] Discharge capacity after 50 cycles / initial discharge capacity Q 50 / Q0(%) test

[0303] The test temperature is 25°C, and the battery is charged to 4.45V (rated voltage of comparative example 1) or 8.90V (other comparative examples and all embodiments) at a constant current of 0.5C, and then charged to 0.025C at a constant voltage. After standing for 5 minutes, the battery is discharged to 3.00V (rated voltage of comparative example 1) or 6.00V (other comparative examples and all embodiments) at 0.5C. The capacity obtained in this step is taken as the initial capacity, and then the battery is tested for 50 cycles at 0.5C charge / 0.5C discharge to calculate the ratio of the capacity of the lithium-ion battery to the initial capacity.

[0304] 3C charging temperature rise test

[0305] The test temperature is 25°C, and the battery is charged at 3C constant current to 4.45V (rated voltage of comparative example 1) or 8.90V (other comparative examples and all embodiments), and charged at constant voltage to 0.025C. During the process, a thermocouple is placed at the center of the battery cell to test the temperature change during the charging process in real time. The highest temperature value minus the test temperature of 25°C is recorded as the 3C charging temperature rise.

[0306] Nail penetration rate test

[0307] The lithium-ion battery to be tested is charged at a constant current of 0.05C to a voltage of 4.45V (rated voltage of comparative example 1) or 8.90V (other comparative examples and all embodiments), and then charged at a constant voltage to a current of 0.025C (cut-off current) to fully charge the battery, and record the appearance of the battery before the test. The battery is subjected to a nail penetration test in an environment of 25±3°C, with a steel nail diameter of 4mm and a puncture speed of 30mm / s. The nail penetration positions are located at 15mm from the edge of the Al pole tab electrode assembly and 15mm from the edge of the Ni pole tab electrode assembly, respectively. The test is stopped after 3.5min or the surface temperature of the electrode assembly drops to 50°C. Ten electrode assemblies are grouped together to observe the battery status during the test. The battery does not burn or explode as the criterion, and 9 or more times out of 10 nail penetration tests are judged to have passed the nail penetration test.

[0308] Table 1 Test parameters and corresponding experimental results of various embodiments and comparative examples

[0309]

[0310]

[0311] As shown in Table 1, compared with Comparative Examples 2-4, except for Example 15, the energy density of the embodiments of the present invention is increased. It can be seen that the separator series structure lithium ion battery of the embodiment of the present invention has a higher energy density than the existing two independent electrode assemblies external series structure lithium ion battery, two independent electrode assemblies head-to-tail series structure lithium ion battery, and two independent electrode assemblies side-by-side series structure lithium ion battery (NG means not measured).

[0312] Compared with comparative examples 1-9, the packaging strength of embodiments 1-5, 7, 11-27 of the present invention is increased, and the nail penetration ratio of embodiments 1-5, 7-12, 15-16, 18, 20-23, and 25 of the present invention is higher than that of comparative examples 1-4 and 9;

[0313] Compared with comparative examples 1-2, the drop damage ratios of embodiments 1-10, 12-14, 16-17, 19, and 24-27 of the present invention are increased, but the discharge voltage of the lithium-ion battery of the single electrode assembly of comparative example 1 is low, and the lithium-ion battery of the two independent electrode assemblies in external series structure of comparative example 2 requires the discharge voltages of the two electrode assemblies to be similar, otherwise short circuit is likely to occur, and embodiments 11, 15, 18, and 20-23 of the present invention still have the same drop damage ratio as comparative example 1-2; compared with comparative examples 3-4, the drop damage ratios of embodiments 1-5, 7, 11-12, 15-18, 20-23, and 25 of the present invention are reduced, indicating that the drop damage ratios are lower than those of the existing lithium-ion batteries with two independent electrode assemblies in head-to-tail series structure and the lithium-ion batteries with two independent electrode assemblies in parallel in series structure; compared with comparative examples 8-9, the drop damage ratios of the embodiments of the present invention are significantly reduced, indicating that the separator prepared by the present invention can be well resistant to drop damage when applied to lithium-ion batteries.

[0314] In addition to the fact that the 3C charging temperature rise of the single-electrode lithium-ion battery of the embodiment of the present invention is lower than that of Comparative Example 1, the charging temperature rise of the embodiment of the present invention is basically unchanged compared with Comparative Examples 2-4 and 7-9.

[0315] Compared with the comparative example, the ratio of the discharge capacity after 50 cycles to the initial discharge capacity of the embodiment of the present invention does not change substantially.

[0316] It can be seen that the separator prepared by the present invention can be applied to lithium-ion batteries to improve the packaging reliability of lithium-ion batteries, and a good technical effect is achieved.

[0317] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An electrochemical device comprising at least one separator and a plurality of electrode assemblies located within an outer package, wherein: The separator divides the interior of the outer package into a plurality of independent sealed chambers, the plurality of electrode assemblies are respectively arranged in the plurality of sealed chambers, the separator has ion insulation and comprises an intermediate layer and a packaging layer, the packaging layer is located on the upper and lower surfaces of the intermediate layer; The material of the intermediate layer includes at least one of a carbon material, a first polymer material or a metal material; The material of the encapsulation layer includes a second polymer material; The temperature at which the encapsulation layer starts to soften is at least 10° C. lower than the temperature at which the intermediate layer starts to soften.

2. The electrochemical device according to claim 1, wherein: The edges of the two surfaces of the intermediate layer are covered by the encapsulation layer, and the area of ​​the encapsulation layer accounts for 30% to 100% of the area of ​​the intermediate layer.

3. The electrochemical device according to claim 2, wherein: At least one surface of the intermediate layer is entirely covered by the encapsulation layer.

4. The electrochemical device according to claim 1, wherein The carbon material includes at least one of carbon felt, carbon film, carbon black, acetylene black, fullerene, conductive graphite film or graphene film.

5. The electrochemical device according to claim 1, wherein The first polymer material includes: polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyetheretherketone, polyimide, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-co-chlorotrifluoroethylene), silicone, vinylon, polypropylene, anhydride-modified polypropylene, polyethylene, ethylene and its copolymers, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester, polysulfone, amorphous α-olefin copolymer or at least one of the derivatives of the above substances.

6. The electrochemical device according to claim 1, wherein The metal material includes at least one of Ni, Ti, Ag, Au, Pt, Fe, Co, Cr, W, Mo, Pb, In, Zn or stainless steel.

7. The electrochemical device according to claim 1, wherein: The second polymer material includes: polypropylene, anhydride-modified polypropylene, polyethylene, ethylene and its copolymers, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyamide, polyester, amorphous α-olefin copolymer or at least one of the derivatives of the above substances.

8. The electrochemical device according to claim 1, wherein The separator has a thickness of 2 μm to 500 μm.

9. The electrochemical device according to claim 1, wherein: The temperature at which the intermediate layer material begins to soften is greater than 130°C.

10. The electrochemical device according to claim 1, wherein The temperature at which the packaging layer material begins to soften is 120° C. to 240° C.

11. The electrochemical device according to claim 1, having at least one of the following features: (a) the thickness of the separator is 5 μm to 50 μm; (b) the temperature at which the intermediate layer material begins to soften is greater than 150° C.; (c) The temperature at which the encapsulation layer material begins to soften is between 130°C and 170°C.

12. The electrochemical device according to claim 1, wherein The outermost layer of the electrode assembly includes a separator, and the separator is adjacent to the separator.

13. The electrochemical device according to claim 1, wherein The outermost layer of at least one of the electrode assemblies comprises a separator, and the separator is adjacent to the separator; the outermost layer of at least one of the electrode assemblies comprises a current collector, and the current collector is adjacent to the other side of the separator.

14. The electrochemical device according to claim 1, wherein The separator has electronic conductivity, the outermost layer of the electrode assembly includes a current collector, the current collector is adjacent to the separator, and the current collectors of the electrode assemblies on both sides of the separator have opposite polarities.

15. The electrochemical device according to claim 1, wherein The separator has electronic insulation properties, and the outermost layer of the electrode assembly includes a current collector, which is adjacent to the separator.

16. An electronic device, comprising the electrochemical device according to any one of claims 1 to 15.

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