Outer packaging and preparation method thereof, secondary battery, battery module, battery pack

Abstract

The present application provides an outer packaging and a preparation method thereof, a secondary battery, a battery module, a battery pack and an electrical device. The outer packaging includes a substrate and a ceramic layer, a waterproof layer and an insulating layer sequentially arranged on the surface of the substrate. The ceramic layer includes α-alumina and / or zirconium oxide with a thickness of 5μm-15μm; the waterproof layer includes at least one of nano-silicon dioxide powder, nano-titanium dioxide powder and nano-ceramic powder with a thickness of 5μm-15μm; the insulating layer includes nano-barium salt and a composite resin material with a thickness of 45μm-55μm. The outer packaging provided by the present application has good deformation resistance, waterproof performance and insulation performance, which is conducive to improving the leakage phenomenon of the secondary battery and improving the safety performance of the secondary battery. In addition, the thickness of the outer packaging does not exceed 85μm, which is conducive to improving the energy density of the secondary battery.

Description

Technical Field

[0001] The present application relates to the technical field of lithium batteries, and in particular to an outer package and a preparation method thereof, a secondary battery, a battery module, a battery pack and an electrical device. Background Art

[0002] Lithium-ion batteries are widely used in wearable devices, smart phones, drones, electric vehicles, large-scale energy storage equipment and other fields due to their advantages such as high energy density, long cycle life and no memory effect. They have become the most promising new green chemical power source in the world today.

[0003] During the preparation process of lithium-ion batteries, a layer of insulating blue film is usually coated on the outside of the outer packaging to provide insulation protection. However, there are overlapping areas of the blue film during the coating process, which leads to a decrease in the thickness uniformity of the battery cell. In addition, the thickness of the blue film commonly used in the prior art is 110μm, which will also affect the energy density of the lithium-ion battery. Secondly, the blue film is coated later and may not fit completely with the outer packaging, thus posing a risk of leakage. Summary of the invention

[0004] The present application has been made in view of the above-mentioned problems, and an object of the present application is to improve the safety performance of secondary batteries.

[0005] In order to achieve the above-mentioned objectives, the present application provides an outer packaging and a preparation method thereof, a secondary battery, a battery module, a battery pack and an electrical device.

[0006] The first aspect of the present application provides an outer packaging, which includes a substrate and a ceramic layer, a waterproof layer and an insulating layer sequentially arranged on the surface of the substrate, wherein the ceramic layer includes α-alumina and / or zirconium oxide, with a thickness of 5μm-15μm; the waterproof layer includes at least one of nano-silicon dioxide powder, nano-titanium dioxide powder and nano-ceramic powder, with a thickness of 5μm-15μm; the insulating layer includes nano-barium salt and composite resin material, with a thickness of 45μm-55μm. The outer packaging provided by the present application has good deformation resistance, waterproof performance and insulating performance, which is conducive to improving the leakage phenomenon of secondary batteries and improving the safety performance of secondary batteries. In addition, the thickness of the outer packaging does not exceed 85μm, which is conducive to improving the energy density of secondary batteries.

[0007] In any embodiment, the ceramic layer further comprises a binder, and the mass percentage of the binder is 0.5%-2.5% based on the mass of the ceramic layer, and the binder comprises at least one of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin. By selecting the above binder and regulating the mass percentage of the binder within the above range, it is beneficial to improve the deformation resistance of the outer packaging.

[0008] In any embodiment, the nano ceramic powder includes alumina ceramic and / or zirconia ceramic. The selection of the nano ceramic powder is beneficial to improving the waterproof performance of the outer packaging.

[0009] In any embodiment, the particle sizes of the nano silicon dioxide powder, the nano titanium dioxide powder and the nano ceramic powder are independently selected from 20nm-500nm. By adjusting the particle sizes of the nano silicon dioxide powder, the nano titanium dioxide powder and the nano ceramic powder within the above range, it is beneficial to improve the waterproof performance of the outer packaging.

[0010] In any embodiment, the mass ratio of the nano-barium salt to the composite resin material is 1:5-3:5. By adjusting the mass ratio of the nano-barium salt to the composite resin material within the above range, it is beneficial to improve the insulation performance of the outer packaging.

[0011] In any embodiment, the nano barium salt includes at least one of barium sulfate and barium carbonate, and the composite resin material includes epoxy resin-oxazolidone. By selecting the above nano barium salt and composite resin material, the obtained outer packaging has good insulation performance.

[0012] In any embodiment, there is a stearic acid coating layer on the surface of the nano barium salt particles, and the stearic acid coating layer includes stearic acid (octadecanoic acid). The nano barium salt is coated with the stearic acid coating layer, which is beneficial to improving the mechanical properties of the outer packaging and the performance of resisting large current impact.

[0013] A second aspect of the present application provides a method for preparing an outer packaging in any of the aforementioned embodiments, comprising the following steps:

[0014] Providing a ceramic layer, a waterproof layer and an insulating layer, and sequentially arranging the ceramic layer, the waterproof layer and the insulating layer on the surface of a substrate;

[0015] The ceramic layer comprises α-alumina and / or zirconium oxide and has a thickness of 5 μm-15 μm;

[0016] The waterproof layer comprises at least one of nano silicon dioxide powder, nano titanium dioxide powder and nano ceramic powder, and has a thickness of 5 μm-15 μm;

[0017] The insulating layer comprises nano barium salt and composite resin material and has a thickness of 45 μm-55 μm.

[0018] A third aspect of the present application provides a secondary battery, comprising the outer package of the first aspect of the present application.

[0019] A fourth aspect of the present application provides a battery module, comprising the secondary battery of the third aspect of the present application.

[0020] A fifth aspect of the present application provides a battery pack comprising the battery module of the fourth aspect of the present application.

[0021] The sixth aspect of the present application provides an electrical device comprising at least one selected from the secondary battery of the third aspect of the present application, the battery module of the fourth aspect of the present application, or the battery pack of the fifth aspect of the present application.

[0022] Beneficial effects of this application:

[0023] The present application provides an outer packaging and a preparation method thereof, a secondary battery, a battery module, a battery pack and an electrical device. The outer packaging includes a substrate and a ceramic layer, a waterproof layer and an insulating layer sequentially arranged on the surface of the substrate. The ceramic layer includes α-alumina and / or zirconium oxide, and the thickness is 5μm-15μm; the waterproof layer includes at least one of nano silicon dioxide powder, nano titanium dioxide powder and nano ceramic powder, and the thickness is 5μm-15μm; the insulating layer includes nano barium salt and a composite resin material, and the thickness is 45μm-55μm. Among them, the ceramic layer is in direct contact with the substrate. Since the ceramic layer has good deformation resistance, combined with the waterproof layer and the insulating layer, the outer packaging has good deformation resistance, waterproof performance and insulating performance at the same time. At the same time, the ceramic layer, the waterproof layer and the insulating layer are directly arranged on the substrate in sequence to form a whole with good thickness uniformity, and can completely cover the substrate, which is conducive to improving the leakage phenomenon of the secondary battery and improving the safety performance of the secondary battery. In addition, the thickness of the outer packaging does not exceed 85μm, which is conducive to improving the energy density of the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic cross-sectional structure diagram of an outer package according to an embodiment of the present application;

[0025] Figure 2 is a schematic diagram of a secondary battery according to an embodiment of the present application;

[0026] Figure 3 yes Figure 2 An exploded view of a secondary battery according to an embodiment of the present application is shown;

[0027] Figure 4 is a schematic diagram of a battery module according to an embodiment of the present application;

[0028] Figure 5 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0029] Figure 6 yes Figure 5 An exploded view of a battery pack according to an embodiment of the present application is shown;

[0030] Figure 7 FIG. 1 is a schematic diagram of an electric device using a secondary battery according to an embodiment of the present application as a power source.

[0031] Description of reference numerals:

[0032] 10 battery pack; 11 upper box; 12 lower box; 20 substrate; 31 ceramic layer; 32 waterproof layer; 33 insulating layer; 4 battery module; 5 secondary battery; 51 shell; 52 electrode assembly; 53 cover plate. DETAILED DESCRIPTION

[0033] Below, the outer packaging and its preparation method, secondary battery, battery module, battery pack and electrical device of the present application are described in detail with appropriate reference to the drawings. However, there are cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0034] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0035] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0036] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0037] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0038] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0039] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0040] In the process of studying the outer packaging of batteries, the applicant discovered that in the prior art, in order to improve the insulation of secondary batteries, a layer of blue film is usually coated on the outer shell of the battery, but the blue film has overlapping areas during the coating process, resulting in a decrease in the thickness uniformity of the battery cell, and the blue film is coated later, and there is a situation where it cannot completely fit the outer packaging, thereby posing a risk of leakage. In addition, the commonly used blue film thickness is 110μm, which will affect the energy density of lithium-ion batteries. In order to improve the safety performance of secondary batteries, the present application provides an outer packaging that can be used as an outer packaging for secondary batteries to improve the safety performance of secondary batteries, so that the secondary batteries have better safety performance when used in electrical devices.

[0041] In one embodiment of the present application, the present application proposes an outer packaging, such as Figure 1 , which is a schematic diagram of the cross-sectional structure of the outer packaging along its own thickness direction. The outer packaging includes a substrate 20 and a ceramic layer 31, a waterproof layer 32 and an insulating layer 33 arranged on the surface of the substrate 20 in sequence. The ceramic layer includes α-alumina and / or zirconium oxide, with a thickness of 5μm-15μm; the waterproof layer includes at least one of nano silicon dioxide powder, nano titanium dioxide powder, and nano ceramic powder, with a thickness of 5μm-15μm; the insulating layer includes nano barium salt and a composite resin material, with a thickness of 45μm-55μm.

[0042] Although the mechanism is not clear, the applicant unexpectedly discovered that the ceramic layer in the outer packaging of the present application is in direct contact with the substrate. Since the ceramic layer has good deformation resistance, combined with the waterproof layer and the insulating layer in the outer packaging, the outer packaging has good deformation resistance, waterproof performance and insulating performance. At the same time, the ceramic layer, the waterproof layer and the insulating layer are directly arranged on the substrate in sequence to form a whole with good thickness uniformity, and can completely cover the substrate, which is conducive to improving the leakage phenomenon of the secondary battery and improving the safety performance of the secondary battery. In addition, the total thickness of the ceramic layer, the waterproof layer and the insulating layer does not exceed 85μm, which is conducive to improving the energy density of the secondary battery.

[0043] In some embodiments, the ceramic layer further includes a binder, and the mass percentage of the binder is 0.5%-2.5% based on the mass of the ceramic layer, and the binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin. When the binder content is too low (e.g., less than 0.5%) or too high (e.g., greater than 2.5%), the deformation resistance of the outer packaging will be affected. By selecting the above-mentioned binder and regulating the mass percentage of the binder within the above range, it is beneficial to improve the deformation resistance of the outer packaging.

[0044] The present application has no particular limitation on the particle sizes of α-alumina and zirconia, as long as the purpose of the present application can be achieved. For example, the particle size of α-alumina is 20nm-500nm, and the particle size of zirconia is 20nm-500nm.

[0045] In some embodiments, the nano ceramic powder includes alumina ceramic and / or zirconia ceramic. The selection of the nano ceramic powder is beneficial to improving the waterproof performance of the outer packaging.

[0046] In some embodiments, the particle sizes of the nano silicon dioxide powder, the nano titanium dioxide powder and the nano ceramic powder are independently selected from 20nm-500nm. By adjusting the particle sizes of the nano silicon dioxide powder, the nano titanium dioxide powder and the nano ceramic powder within the above range, it is beneficial to improve the waterproof performance of the outer packaging.

[0047] In some embodiments, the mass ratio of the nano-barium salt to the composite resin material is 1:5-3:5. When the mass ratio of the nano-barium salt to the composite resin material is small (e.g., less than 1:5) or large (e.g., greater than 3:5), the insulation performance of the outer packaging will be affected. By regulating the mass ratio of the nano-barium salt to the composite resin material within the above range, it is beneficial to improve the insulation performance of the outer packaging.

[0048] In some embodiments, the nano barium salt includes at least one of barium sulfate and barium carbonate, and the composite resin material includes epoxy resin-oxazolidone. By selecting the above nano barium salt and the composite resin material, the obtained outer packaging has good insulation performance. The present application has no particular restrictions on the particle size of the nano barium salt, as long as the purpose of the present application can be achieved, for example, the particle size of the nano barium salt is 10nm-500nm.

[0049] In some embodiments, there is a stearic acid coating layer on the surface of the nano barium salt particles, and the stearic acid coating layer includes stearic acid (octadecanoic acid). The nano barium salt is coated with the stearic acid coating layer, which is beneficial to improving the mechanical properties of the outer packaging and the performance of resisting large current shocks. The application itself has no particular restrictions on the preparation method of the stearic acid coating layer of the nano barium salt, and a preparation method known in the art can be used as long as the purpose of the application can be achieved.

[0050] In some embodiments, the insulating layer includes a dark dye, and the obtained insulating layer is dark. In the process of preparing the outer packaging, if the insulating layer is unevenly coated or incompletely coated, the waterproof layer will be exposed, which is conducive to discovering defective products in the production process. The present application has no particular restrictions on the above-mentioned dark dye, as long as the purpose of the present application can be achieved, such as black dye or dark blue dye. The present application has no particular restrictions on the type of dark dye, and dark dyes known in the art can be used, as long as they do not affect the insulating properties of the insulating layer.

[0051] The present application also provides a method for preparing an outer packaging in any of the aforementioned embodiments, which comprises the following steps: providing a ceramic layer, a waterproof layer and an insulating layer, and sequentially arranging the ceramic layer, the waterproof layer and the insulating layer on the surface of a substrate; the ceramic layer comprises α-alumina and / or zirconium oxide, with a thickness of 5μm-15μm; the waterproof layer comprises at least one of nano-silicon dioxide powder, nano-titanium dioxide powder and nano-ceramic powder, with a thickness of 5μm-15μm; the insulating layer comprises nano-barium salt and a composite resin material, with a thickness of 45μm-55μm.

[0052] The present application has no particular restrictions on the preparation methods of the ceramic layer, the waterproof layer and the insulating layer, as long as the purpose of the present application can be achieved. For example, the preparation method of the ceramic layer may include but is not limited to plasma arc spraying, thermal spraying, magnetron sputtering, etc., the preparation method of the waterproof layer may include but is not limited to dispensing machine spraying, etc., and the preparation method of the insulating layer may include but is not limited to coating, etc.

[0053] In some embodiments, the substrate of the outer packaging can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The substrate of the outer packaging can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0054] In addition, the secondary battery, battery module, battery pack, and electric device of the present application will be described below with reference to the drawings as appropriate.

[0055] In one embodiment of the present application, a secondary battery is provided, which includes an outer package in any of the above embodiments or an outer package prepared by the preparation method in any of the above embodiments.

[0056] Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.

[0057] [Positive electrode]

[0058] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector.

[0059] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0060] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0061] In some embodiments, the positive electrode active material may adopt a positive electrode active material for a battery that is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 )、LiNi 0.5Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 )), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds, etc. Examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0062] In some embodiments, the positive electrode film layer may further optionally include a positive electrode film layer binder. As an example, the positive electrode film layer binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0063] In some embodiments, the positive electrode film layer may further include a conductive agent, which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0064] In some embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0065] [Negative electrode]

[0066] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0067] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0068] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0069] In some embodiments, the negative electrode active material may adopt the negative electrode active material for the battery known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0070] In some embodiments, the negative electrode film layer may further optionally include a negative electrode film layer binder. The negative electrode film layer binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

[0071] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0072] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0073] In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0074] [Electrolytes]

[0075] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0076] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0077] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0078] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0079] In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0080] [Isolation film]

[0081] In some embodiments, the secondary battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0082] In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0083] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0084] In some embodiments, the secondary battery may include the outer packaging in any of the aforementioned embodiments, and the outer packaging may be used to encapsulate the electrode assembly and the electrolyte.

[0085] The present application has no particular limitation on the shape of the secondary battery, which may be cylindrical, square or any other shape. Figure 2 The secondary battery 5 is a square structure as an example.

[0086] In some embodiments, reference Figure 3 , the outer packaging may include a shell 51 and a cover plate 53. Among them, the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0087] In some embodiments, secondary batteries may be assembled into a battery module. The number of secondary batteries contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

[0088] Figure 4 4 is an example of a battery module. Figure 4 In the battery module 4, the plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of secondary batteries 5 may be fixed by fasteners.

[0089] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of secondary batteries 5 are received in the receiving space.

[0090] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

[0091] Figure 5 and Figure 6 1 is a battery pack 10 as an example. Figure 5 and Figure 6 The battery pack 10 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 11 and a lower box body 12. The upper box body 11 can cover the lower box body 12 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0092] In addition, the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.

[0093] As the electrical device, a secondary battery, a battery module or a battery pack may be selected according to its usage requirements.

[0094] Figure 7 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the high power and high energy density requirements of the power consumption device for the secondary battery, a battery pack or a battery module can be used.

[0095] Another example of a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a secondary battery may be used as a power source.

[0096] Example

[0097] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0098] Example 1

[0099] <Preparation of outer packaging>

[0100] The aluminum-plastic film shell is used as the base material.

[0101] (1) Preparation of ceramic layer

[0102] α-alumina powder (particle size of 20nm-100nm) is added to deionized water and ultrasonic vibration is used to evenly disperse the α-alumina powder in the deionized water, then the binder polyvinylidene fluoride is added and put into a ball mill for 2h to mix evenly to obtain a mixed slurry, and then the mixed slurry is dried by spray drying to solidify into spherical particles, and then sieved to form micron-sized alumina nanoparticles, and then sintered at 1100°C for 5h, kept warm for 10min, and then ground to obtain alumina ceramic material nano sintered powder. Among them, the mass percentage of the binder is 0.5%.

[0103] The nano-sintered powder of alumina ceramic material is heated to a molten state and sprayed onto one surface of the substrate by a plasma spray gun to form a ceramic layer with a thickness of 10 μm, wherein the diameter of the spray gun orifice is 2 cm and the spray height is 30 cm.

[0104] (2) Preparation of waterproof layer

[0105] Nano silicon dioxide powder with a particle size of 20nm-200nm, nano titanium dioxide powder with a particle size of 20nm-200nm, and alumina nano ceramic powder with a particle size of 20nm-200nm are mixed in a mass ratio of 2:1:7, and then propylene glycol methyl ether is added as a solvent to obtain a waterproof layer slurry with a solid content of 42wt%. Then, the waterproof layer slurry is sprayed on the ceramic layer prepared in step (2) by a dispensing machine to obtain a waterproof layer with a thickness of 10μm. The nozzle diameter of the dispensing machine is 0.5mm, the spray atomization pressure is 15psi, and the spraying height is 10cm.

[0106] (3) Preparation of insulation layer

[0107] The natural mineral barium salt (mainly composed of BaSO4) is ball-milled into a nanometer powder with a particle size of 50nm-200nm by a high-efficiency ball mill, and then dimethyl sulfoxide is added as a solvent to obtain a suspension with a solid content of 20wt%-30wt%, and stirred evenly, and hydrochloric acid or sodium hydroxide is added to adjust the pH value of the suspension to 7-8. Then suction filtration is performed, and the filter cake is washed with deionized water until no chloride ions are detected by a 0.1mol / L AgNO3 solution, and then the filter cake is dried at 120°C, and then crushed to obtain a natural barium salt nanometer powder BaSO4, and then ground in a ball mill for 12h to obtain a nanometer barium salt BaSO4 with a particle size of 100nm. The above-obtained nanometer barium salt is mixed with stearic acid in a mass ratio of 9:1 to obtain a nanometer barium salt coated with a stearic acid coating layer. The nano barium salt containing a stearic acid coating layer, the composite resin material epoxy resin-oxazolidone, and the black pigment carbon black were mixed in a mass ratio of 2:5:0.002, and ball-milled in a ball mill for 24 hours to obtain an insulating coating material.

[0108] The coating material prepared above was added into the solvent dimethyl sulfoxide to obtain an insulating layer slurry with a solid content of 20 wt%. Then, the waterproof layer prepared in step (3) was coated by a coating method, and an insulating layer with a thickness of 50 μm was obtained after drying.

[0109] <Preparation of lithium-ion batteries>

[0110] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is placed between the positive electrode sheet and the negative electrode sheet to play an isolating role, and then they are wound to obtain an electrode assembly; the electrode assembly is placed in the outer packaging prepared above, and after drying, the electrolyte is injected, and after vacuum packaging, standing, forming, shaping and other processes, a lithium-ion battery is obtained.

[0111] Example 2 to Example 6

[0112] Except for adjusting the relevant preparation parameters according to Table 1, the rest is the same as Example 1. In Example 4, when preparing the insulating layer, the nano barium salt BaSO4 is replaced by BaCO3 known in the prior art.

[0113] Comparative Example 1

[0114] The process is the same as that of Example 1 except that the ceramic layer, the waterproof layer and the insulating layer are not provided on the surface of the substrate, and a blue film with a thickness of 110 μm is coated on the surface of the substrate.

[0115] Comparative Example 2

[0116] Except that no ceramic layer is provided on the surface of the substrate, the rest is the same as that of Example 1.

[0117] Comparative Example 3

[0118] Except for adjusting the relevant preparation parameters according to Table 1, the rest is the same as Example 1.

[0119] Performance Testing:

[0120] Leakage current failure rate test:

[0121] An insulation tester is used to test the leakage current of the lithium-ion battery. One of the probes in the insulation tester contacts the aluminum layer in the aluminum-plastic film of the outer packaging, and the other probe contacts the insulating layer or blue film set on the outer packaging. The test voltage is 1500V, the test pressure is 800kgf, and the test time is 3s. When the leakage current is greater than or equal to 1.5mA, it is recorded as a leaky lithium-ion battery.

[0122] Leakage current failure rate=number of leaking lithium-ion batteries / total number of tested lithium-ion batteries×100%, wherein the total number of tested lithium-ion batteries is 1000.

[0123] Thickness standard deviation σ calculation:

[0124] The thickness of 100 lithium-ion batteries was measured using a micrometer, and then the standard deviation σ of the thickness of the lithium-ion batteries was calculated. The above standard deviation is a standard deviation well known in the art.

[0125] Waterproof performance test:

[0126] Place the lithium-ion battery in a 3.5% NaCl aqueous solution with a water depth of 25 mm, and then use the ohm range of a multimeter to test whether there is leakage current. One end of the multimeter is fixed on the top cover of the lithium-ion battery (non-pole area), and the other end is placed in water. If the measured resistance value is greater than or equal to 1 megohm, the waterproof performance test of the lithium-ion battery passes; if the measured resistance value is less than 1 megohm, the waterproof performance test of the lithium-ion battery fails. Each embodiment and comparative example tests 100 lithium-ion batteries, and the number of lithium-ion batteries that pass the test is recorded as the final result.

[0127] The preparation parameters and performance tests of various embodiments and comparative examples are shown in Table 1.

[0128] Table 1

[0129]

[0130] Note: “ / ” in Table 1 indicates that there is no corresponding preparation parameter or substance.

[0131] As shown in Table 1, the leakage current failure rate of the lithium-ion battery obtained by using the outer packaging provided by the present application in Example 1 is 0%, while the leakage current failure rate of the lithium-ion battery obtained by coating the outer surface of the outer packaging with a blue film in the prior art in Comparative Example 1 is 0.1%, indicating that the outer packaging provided by the present application can improve the leakage phenomenon of the lithium-ion battery, thereby improving the safety performance of the lithium-ion battery. At the same time, the thickness standard deviation σ of the lithium-ion battery obtained by using the outer packaging provided by the present application in Example 1 is 0.059, while the thickness standard deviation σ of the lithium-ion battery obtained by coating the outer surface of the outer packaging with a blue film in the prior art in Comparative Example 1 is 0.183, indicating that the outer packaging provided by the present application is conducive to improving the thickness uniformity of the same batch of lithium-ion batteries. In addition, after the waterproof test, the number of lithium-ion batteries passed in Example 1 and Comparative Example 1 is 100, indicating that the outer packaging provided by the present application also has good waterproof performance.

[0132] It can be seen from Example 1 and Comparative Example 2 that when the outer packaging includes a ceramic layer, a waterproof layer and an insulating layer at the same time, the lithium-ion battery has better safety performance. In the process of preparing the ceramic layer, the waterproof layer and the insulating layer, the type of material in the ceramic layer and the mass percentage of the binder, the thickness of the ceramic layer, the type of nano-ceramic powder in the waterproof layer and the thickness of the waterproof layer, the mass ratio of the nano-barium salt and the composite resin material in the insulating layer, the type of the nano-barium salt and the thickness of the insulating layer usually affect the performance of the lithium-ion battery. It can be seen from Examples 1 to 6 that when the above parameters are within the scope of this application, the obtained lithium-ion battery has good safety performance, waterproof performance and thickness uniformity; it can be seen from Examples 1 to 6 and Comparative Example 3 that when the thickness of the ceramic layer, the waterproof layer and the insulating layer is within the scope of this application, the lithium-ion battery has better safety performance and waterproof performance at the same time, and the lithium-ion batteries of the same batch have better thickness uniformity.

[0133] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. An outer package, comprising a substrate and a ceramic layer, a waterproof layer and an insulating layer sequentially arranged on the surface of the substrate, wherein the ceramic layer comprises α-alumina and / or zirconia and has a thickness of 5 μm-15 μm; The waterproof layer comprises at least one of nano silicon dioxide powder, nano titanium dioxide powder and nano ceramic powder, and has a thickness of 5 μm-15 μm; The insulating layer comprises nano-barium salt and composite resin material, and has a thickness of 45 μm-55 μm. Based on the mass of the ceramic layer, the mass percentage of the binder is 0.5%-2.5%, and the binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

2. The outer packaging according to claim 1, wherein: The nano ceramic powder includes alumina ceramic and / or zirconia ceramic.

3. The outer package according to claim 1, wherein: The particle sizes of the nano silicon dioxide powder, the nano titanium dioxide powder and the nano ceramic powder are each independently selected from 20 nm to 500 nm.

4. The outer package according to claim 1, wherein: The mass ratio of the nano barium salt to the composite resin material is 1:5-3:

5.

5. The outer package according to claim 1, wherein: The nano barium salt includes at least one of barium sulfate and barium carbonate, and the composite resin material includes epoxy resin-oxazolidinone.

6. The outer package according to claim 1, wherein: A stearic acid coating layer exists on the surface of the nano barium salt particles, and the stearic acid coating layer comprises stearic acid.

7. A method for preparing an outer packaging as claimed in any one of claims 1 to 6, comprising the following steps: Providing a ceramic layer, a waterproof layer and an insulating layer, and sequentially arranging the ceramic layer, the waterproof layer and the insulating layer on the surface of a substrate; The ceramic layer comprises α-alumina and / or zirconium oxide and has a thickness of 5 μm-15 μm; The waterproof layer comprises at least one of nano silicon dioxide powder, nano titanium dioxide powder and nano ceramic powder, and has a thickness of 5 μm-15 μm; The insulating layer comprises nano barium salt and composite resin material and has a thickness of 45 μm-55 μm.

8. A secondary battery comprising the outer package according to any one of claims 1 to 6. 9 . A battery module comprising the secondary battery according to claim 8 . 10 . A battery pack comprising the battery module according to claim 9 . 11 . An electrical device comprising at least one selected from the secondary battery of claim 8 , the battery module of claim 9 , or the battery pack of claim 10 .

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