WO2023093340A1

WO2023093340A1 - Outer package and preparation method therefor, secondary battery, battery module and battery pack

Info

Publication number: WO2023093340A1
Application number: PCT/CN2022/124888
Authority: WO
Inventors: 吴宇堃; 葛销明
Original assignee: 宁德时代新能源科技股份有限公司
Priority date: 2021-11-24
Filing date: 2022-10-12
Publication date: 2023-06-01
Also published as: CN115842202A

Abstract

Provided in the present application are an outer package and a preparation method therefor, a secondary battery, a battery module, a battery pack and an electric device. The outer package comprises a base material, and a ceramic layer, a waterproof layer and an insulating layer which are sequentially arranged on the surface of the base material, wherein the ceramic layer comprises α-aluminum oxide and/or zirconium oxide and has a thickness of 5-15 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 5-15 μm; and the insulating layer comprises nano barium salt and a composite resin material, and has a thickness of 45-55 μm. The outer package provided in the present application has good deformation resistance, waterproof performance and insulation performance, and is beneficial for improving the electric leakage phenomenon of a secondary battery so as to improve the safety performance of the secondary battery. In addition, the thickness of the outer package does not exceed 85 μm, which is beneficial for improving the energy density of the secondary battery.

Description

A kind of outer packaging and its preparation method, secondary battery, battery module, battery pack

Cross References to Related Applications

This application claims the priority of the Chinese patent application 202111403638.6 filed on November 24, 2021, entitled "An Outer Packaging and Its Preparation Method, Secondary Battery, Battery Module, and Battery Pack". incorporated herein by reference.

technical field

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

Background technique

Due to its high energy density, long cycle life and no memory effect, lithium-ion batteries are widely used in wearable devices, smart phones, unmanned aerial vehicles, electric vehicles and large-scale energy storage equipment. Development potential of new green chemical power sources.

During the preparation process of lithium-ion batteries, an insulating blue film is usually coated on the outside of the outer packaging to play the role of insulation protection. However, there is an overlapping area in the coating process of the blue film, which leads to a decrease in the uniformity of the thickness of the battery cell, and the thickness of the blue film commonly used in the prior art is 110 μm, which will also affect the energy density of the lithium-ion battery. Secondly, the blue film is coated in the later stage, and there is a situation that it cannot be completely conformed to the outer packaging, so there is a risk of electric leakage.

Contents of the invention

This application was made in view of the said subject, and it aims at improving the safety performance of a secondary battery.

In order to achieve the above purpose, the present application provides an outer package and a preparation method thereof, a secondary battery, a battery module, a battery pack and an electrical device.

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 arranged on the surface of the substrate in sequence, and the ceramic layer includes α-alumina and/or zirconia , with a thickness of 5 μm-15 μm; the waterproof layer includes at least one of nano-silica powder, nano-titanium dioxide powder, and nano-ceramic powder, with a thickness of 5 μm-15 μm; the insulating layer includes nano-barium salt and a composite resin material, The thickness is 45μm-55μm. The outer packaging provided by the present application has good deformation resistance, waterproof performance and insulation performance, which is beneficial 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 package is not more than 85 μm, which is beneficial to improve the energy density of the secondary battery.

In any embodiment, the ceramic layer further includes a binder, based on the mass of the ceramic layer, the mass percentage of the binder is 0.5%-2.5%, and the binder includes polyvinylidene fluoride Ethylene, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylic acid at least one of ester resins. By selecting the above binder and adjusting the mass percentage of the binder within the above range, it is beneficial to improve the deformation resistance of the outer package.

In any embodiment, the nano-ceramic powder includes alumina ceramics and/or zirconia ceramics. By selecting the above-mentioned nano-ceramic powder, it is beneficial to improve the waterproof performance of the outer packaging.

In any embodiment, the particle diameters of the nano-silica powder, the nano-titanium dioxide powder and the nano-ceramic powder are each independently selected from 20nm-500nm. By controlling the particle diameters of the nano-silica 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.

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

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-oxazolidinone. By selecting the above-mentioned nano-barium salt and composite resin material, the obtained outer package has good insulation performance.

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). Nano-barium salt is coated with stearic acid coating layer, which is beneficial to improve the mechanical properties of the outer packaging and the performance of high-current impact resistance.

The second aspect of the present application provides a method for preparing the outer packaging in any of the aforementioned embodiments, which includes the following steps:

providing a ceramic layer, a waterproof layer and an insulating layer, and sequentially disposing the ceramic layer, the waterproof layer and the insulating layer on the surface of the substrate;

The ceramic layer includes α-alumina and/or zirconia, with a thickness of 5 μm-15 μm;

The waterproof layer includes at least one of nano-silica powder, nano-titanium dioxide powder, and nano-ceramic powder, with a thickness of 5 μm-15 μm;

The insulating layer includes nanometer barium salt and composite resin material, and the thickness is 45 μm-55 μm.

A third aspect of the present application provides a secondary battery, including the outer packaging of the first aspect of the present application.

A fourth aspect of the present application provides a battery module including the secondary battery of the third aspect of the present application.

A fifth aspect of the present application provides a battery pack, including the battery module of the fourth aspect of the present application.

The sixth aspect of the present application provides an electric device, including 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. kind.

The beneficial effect of this application:

The application provides an outer package and its preparation method, a secondary battery, a battery module, a battery pack, and an electrical device. The outer package includes a base material and a ceramic layer, a waterproof layer, and an insulating layer sequentially arranged on the surface of the base material. The ceramic The layer includes α-alumina and/or zirconia, with a thickness of 5μm-15μm; the waterproof layer includes at least one of nano-silica powder, nano-titania powder, and nano-ceramic powder, with a thickness of 5μm-15μm; the insulating layer includes nano Barium salt and composite resin material, the thickness is 45μm-55μm. Among them, the ceramic layer is in direct contact with the base material. Since the ceramic layer has good deformation resistance and is combined with the waterproof layer and the insulation layer, the outer packaging has good deformation resistance, waterproof performance and insulation performance at the same time. At the same time, the ceramic layer, waterproof layer and insulating layer are directly arranged on the base material in sequence to form a whole with good thickness uniformity and can completely cover the base material, which is conducive to improving the leakage phenomenon of the secondary battery and improving the safety of the secondary battery performance. In addition, the thickness of the outer package is not more than 85 μm, which is beneficial to improve the energy density of the secondary battery.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the accompanying drawings that need to be used in the embodiments of the present application. Obviously, the accompanying drawings described below are only some embodiments of the present application. Those of ordinary skill in the art can also obtain other drawings based on the accompanying drawings on the premise of not paying creative efforts.

Fig. 1 is a schematic cross-sectional structure diagram of an outer package according to an embodiment of the present application;

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

Fig. 3 is an exploded view of the secondary battery according to an embodiment of the present application shown in Fig. 2;

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

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

Fig. 6 is an exploded view of the battery pack according to an embodiment of the present application shown in Fig. 5;

FIG. 7 is a schematic diagram of an electrical device in which a secondary battery is used as a power source according to an embodiment of the present application.

Explanation of reference signs:

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 casing; 52 electrode assembly; 53 cover plate .

Detailed ways

Hereinafter, embodiments of the outer package of the present application, the manufacturing method thereof, the secondary battery, the battery module, the battery pack, and the electrical device will be specifically disclosed in detail with reference to the accompanying drawings. However, unnecessary detailed description may be omitted. For example, detailed descriptions of well-known items and repeated descriptions of substantially the same configurations may be 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.

A "range" disclosed herein is defined in terms of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive and may be combined arbitrarily, ie any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are contemplated. Additionally, if the minimum range values 1 and 2 are listed, and if the

maximum range values

3, 4, and 5 are listed, the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5. In this application, unless otherwise stated, the numerical range "a-b" represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article, and "0-5" is only an abbreviated representation of the combination of these values. In addition, when expressing that a certain parameter is an integer ≥ 2, it is equivalent to disclosing that the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

If there is no special description, all the implementation modes and optional implementation modes of the present application can be combined with each other to form new technical solutions.

If there is no special description, all the technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

Unless otherwise specified, all steps in 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 in sequence, and may also include steps (b) and (a) performed in sequence. For example, mentioning that the method may also include step (c) means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c) , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b) and so on.

If there is no special description, the "comprising" and "comprising" mentioned in this application mean open or closed. For example, the "comprising" and "comprising" may mean that other components not listed may be included or included, or only listed components may be included or included.

In this application, the term "or" is inclusive unless otherwise stated. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied by either of the following: 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).

The applicant found in the process of researching the outer packaging of the battery that in the prior art, in order to improve the insulation of the secondary battery, a layer of blue film is usually coated on the outer shell of the battery, but there is an overlapping area of the blue film during the coating process , leading to a decline in the uniformity of the thickness of the cell, and the blue film is coated in the later stage, and there is a situation that it cannot be completely compliant with the outer packaging, so there is a risk of leakage. In addition, the thickness of the commonly used blue film is 110 μm, which will affect the energy density of lithium-ion batteries. In order to improve the safety performance of the secondary battery, the application provides an outer package, which can be used as the outer package of the secondary battery to improve the safety performance of the secondary battery, so that the secondary battery has better performance when applied to an electric device. safety performance.

In one embodiment of the present application, the present application proposes an outer packaging, as shown in FIG. 1 , which is a schematic cross-sectional structure diagram of the outer packaging along its own thickness direction. A ceramic layer 31, a waterproof layer 32 and an insulating layer 33, the ceramic layer includes α-alumina and/or zirconia, and the thickness is 5 μm-15 μm; the waterproof layer includes nano-silica powder, nano-titanium dioxide powder, nano-ceramic powder At least one, the thickness is 5 μm-15 μm; the insulating layer includes nano-barium salt and composite resin material, and the thickness is 45 μm-55 μm.

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

In some embodiments, the ceramic layer further includes a binder, based on the mass of the ceramic layer, the mass percentage of the binder is 0.5%-2.5%, and the binder includes polyvinylidene fluoride, polytetrafluoroethylene, At least one of fluoroethylene-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin. When the binder content is too low (for example, lower than 0.5%) or too high (for example, higher than 2.5%), the deformation resistance of the outer package will be affected. By selecting the above binder and adjusting the mass percentage of the binder within the above range, it is beneficial to improve the deformation resistance of the outer package.

The present application has no special limitation on the particle size of α-alumina and zirconia, as long as the purpose of this application can be achieved, for example, the particle size of α-alumina is 20nm-500nm, and the particle size of zirconia is 20nm-500nm .

In some embodiments, the nanoceramic powder includes alumina ceramics and/or zirconia ceramics. By selecting the above-mentioned nano-ceramic powder, it is beneficial to improve the waterproof performance of the outer packaging.

In some embodiments, the particle diameters of the nano-silica powder, the nano-titanium dioxide powder and the nano-ceramic powder are each independently selected from 20nm-500nm. By controlling the particle diameters of the nano-silica 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.

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 nano-barium salt and composite resin material is small (for example, less than 1:5) or large (for example, greater than 3:5), the insulation performance of the outer packaging will be affected. By regulating the mass ratio of the nano-barium salt and the composite resin material within the above range, it is beneficial to improve the insulation performance of the outer package.

In some embodiments, the nanobarium salt includes at least one of barium sulfate and barium carbonate, and the composite resin material includes epoxy resin-oxazolidinone. By selecting the above-mentioned nano-barium salt and composite resin material, the obtained outer package has good insulation performance. The present application has no particular limitation 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.

In some embodiments, there is a stearic acid coating layer on the surface of the barium nano-salt particles, and the stearic acid coating layer includes stearic acid (stearic acid). Nano-barium salt is coated with stearic acid coating layer, which is beneficial to improve the mechanical properties of the outer packaging and the performance of high-current impact resistance. The application itself has no special limitation on the preparation method of the stearic acid coating layer of nano-barium salt, and the preparation method known in the art can be used as long as the purpose of the application can be achieved.

In some embodiments, the insulating layer includes a dark dye, and the resulting insulating layer is dark in color. During the preparation of the outer packaging, if the insulating layer is unevenly or incompletely coated, the waterproof layer will be exposed. , so as to facilitate the detection of defective products in the production process. The present application has no particular limitation on the above dark dyes, as long as the purpose of the present application can be achieved, such as black dyes or deep blue dyes. The present application has no particular limitation on the type of dark dye, and dark dyes known in the art can be used as long as the insulating performance of the insulating layer is not affected.

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

The present application has no special restrictions on the preparation methods of the ceramic layer, waterproof layer and insulating layer, as long as the purpose of the application can be achieved, for example, the preparation method of the ceramic layer can include but not limited to plasma arc spraying, thermal spraying, magnetron sputtering The preparation method of the waterproof layer may include but not limited to spraying by a dispenser, and the preparation method of the insulating layer may include but not limited to a coating method.

In some embodiments, the base material of the outer package may be a hard shell, such as a hard plastic shell, aluminum shell, steel shell, and the like. The base material of the outer packaging can also be a soft bag, such as a bag-type soft bag. The material of the soft case may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.

In addition, the secondary battery, the battery module, the battery pack, and the power consumption device of the present application will be described below with appropriate reference to the accompanying drawings.

In one embodiment of the present application, a secondary battery is provided. It includes the outer package in any of the above embodiments or the outer package made by the preparation method in any of the above embodiments.

Typically, a secondary battery includes a positive pole piece, a negative pole piece, an electrolyte, and a separator. During the charging and discharging process of the battery, active ions are intercalated and extracted back and forth between the positive electrode and the negative electrode. The electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece. The separator is arranged between the positive pole piece and the negative pole piece, which mainly plays a role in preventing the short circuit of the positive and negative poles, and at the same time allows ions to pass through.

[Positive pole piece]

The positive pole piece includes a positive current collector and a positive film layer arranged on at least one surface of the positive current collector.

As an example, the positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposing surfaces of the positive electrode current collector.

In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, aluminum foil can 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 can be formed by forming metal materials (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalic acid It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments, the positive electrode active material may be a positive electrode active material known in the art for batteries. As an example, the positive active material may include at least one of the following materials: olivine-structured lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials of batteries can 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 oxides (such as LiCoO ₂ ), lithium nickel oxides (such as LiNiO ₂ ), lithium manganese oxides (such as LiMnO ₂ , LiMn ₂ O ₄ ), 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 O ₂ (also referred to as NCM ₃₃₃ ), LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (also abbreviated as NCM ₅₂₃ ), LiNi _0.5 Co _0.25 Mn _0.25 O ₂ (also abbreviated as NCM ₂₁₁ ), LiNi _0.6 Co _0.2 Mn _0.2 O ₂ (also abbreviated as NCM ₆₂₂ ), LiNi At least one of _0.8 Co _0.1 Mn _0.1 O ₂ (also referred to as NCM ₈₁₁ )), lithium nickel cobalt aluminum oxide (such as LiNi _0.85 Co _0.15 Al _0.05 O ₂ ) and modified compounds thereof. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO ₄ (also abbreviated as LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO ₄ ), phosphoric acid At least one of a composite material of lithium manganese and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

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

In some embodiments, the positive electrode film layer may also optionally include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

In some embodiments, the positive electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the positive electrode sheet, such as positive electrode active material, conductive agent, 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 current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[Negative pole piece]

The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.

As an example, the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposing surfaces of the negative electrode current collector.

In some embodiments, the negative electrode current collector can use a metal foil or a composite current collector. For example, copper foil can be used as the metal foil. The composite current collector may include a base layer of polymer material and a metal layer formed on at least one surface of the base material of polymer material. Composite current collectors can be formed by metal materials (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyethylene terephthalic acid It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments, the negative electrode active material can be a negative electrode active material known in the art for batteries. 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 material, tin-based material, lithium titanate, and the like. The silicon-based material may be selected from at least one of elemental silicon, silicon-oxygen compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of simple tin, tin oxide compounds and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials of batteries can also be used. These negative electrode active materials may be used alone or in combination of two or more.

In some embodiments, the negative electrode film layer may also optionally include a binder for the negative electrode film layer. The negative film binder can be selected from 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).

In some embodiments, the negative electrode film layer may also optionally include a conductive agent. The conductive agent can be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

In some embodiments, the negative electrode film layer may optionally include other additives, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.

In some embodiments, the negative electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the negative electrode sheet, such as negative electrode active material, conductive agent, 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 current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[Electrolyte]

The electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece. The present application has no specific limitation on the type of electrolyte, which can be selected according to requirements. For example, electrolytes can be liquid, gel or all solid.

In some embodiments, the electrolyte is an electrolytic solution. The electrolyte solution includes an electrolyte salt and a solvent.

In some embodiments, the electrolyte salt may be selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, trifluoromethane At least one of lithium sulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium difluorooxalate borate, lithium difluorodifluorooxalatephosphate and lithium tetrafluorooxalatephosphate.

In some embodiments, the solvent may be selected from 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 At least one of ester, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain performances of the battery, such as additives that improve battery overcharge performance, additives that improve high-temperature or low-temperature performance of batteries, and the like.

[Isolation film]

In some embodiments, a separator is further included in the secondary battery. The present application has no particular limitation on the type of the isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.

In some embodiments, the material of the isolation film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without any particular limitation. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and there is no particular limitation.

In some embodiments, the positive pole piece, the negative pole piece and the separator can be made into an electrode assembly through a winding process or a lamination process.

In some embodiments, the secondary battery may include the outer package in any of the foregoing embodiments. The outer package can be used to package the above-mentioned electrode assembly and electrolyte.

The present application has no special limitation on the shape of the secondary battery, which may be cylindrical, square or any other shape. For example, FIG. 2 shows a square-shaped secondary battery 5 as an example.

In some embodiments, referring to FIG. 3 , the outer package may include a housing 51 and a cover 53 . Wherein, the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plates enclose to form an accommodating cavity. The housing 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can cover the opening to close the accommodating cavity. The positive pole piece, the negative pole piece and the separator can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is packaged in the accommodating cavity. 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.

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

FIG. 4 is a battery module 4 as an example. Referring to FIG. 4 , in the battery module 4 , a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 . Of course, it can also be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fixed by fasteners.

Optionally, the battery module 4 may also include a case having a housing space in which a plurality of secondary batteries 5 are accommodated.

In some embodiments, the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

5 and 6 show the battery pack 10 as an example. Referring to FIGS. 5 and 6 , a battery box and a plurality of battery modules 4 disposed in the battery box may be included in the battery pack 10 . 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 module 4 . Multiple battery modules 4 can be arranged in the battery box in any manner.

In addition, the present application also provides an electric 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 of the electric device, and can also be used as an energy storage unit of the electric device. The electric devices may include mobile devices (such as mobile phones, notebook computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, etc.) , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but not limited thereto.

As the electric device, a secondary battery, a battery module or a battery pack can be selected according to its use requirements.

FIG. 7 is an example of an electrical device. The electric 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 electric device for the secondary battery, a battery pack or a battery module may be used.

As another example, a device may be a cell phone, tablet, laptop, or the like. The device is generally required to be light and thin, and a secondary battery can be used as a power source.

Example

Hereinafter, examples of the present application will be described. The embodiments described below are exemplary and are only used for explaining the present application, and should not be construed as limiting the present application. If no specific technique or condition is indicated in the examples, it shall be carried out according to the technique or condition described in the literature in this field or according to the product specification. The reagents or instruments used were not indicated by the manufacturer, and they were all commercially available conventional products.

Example 1

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

Preparation of the ceramic layer

Add α-alumina powder (with a particle size of 20nm-100nm) into deionized water and use ultrasonic vibration to disperse the α-alumina powder evenly in deionized water, then add the binder polyvinylidene fluoride and put it into a ball mill for 2 hours Mix evenly to obtain a mixed slurry, and then use a spray drying method to dry the mixed slurry to solidify into spherical particles, then sieve to form micron-sized alumina nanoparticles, and then sinter at 1100°C for 5 hours at a high temperature, and keep it for 10 minutes. Grinding to obtain nano sintered powder of alumina ceramic material. Wherein, the mass percent content of the binder is 0.5%.

The alumina ceramic material nano-sintered powder 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 nozzle diameter of the spray gun is 2cm, and the spray height is 30cm.

Preparation of waterproof layer

Mix nano-silica 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 according to a mass ratio of 2:1:7, and then Propylene glycol methyl ether was added as a solvent to obtain a waterproof layer slurry with a solid content of 42 wt%. Then spray the waterproof layer slurry on the ceramic layer prepared in step (2) by a glue dispenser to obtain a waterproof layer with a thickness of 10 μm. Among them, the nozzle diameter of the dispenser is 0.5 mm, the spraying atomization air pressure is 15 psi, and the spraying height is 10 cm.

Preparation of insulating layer

The natural mineral barium salt (the main component is BaSO ₄ ) is ball-milled into a nano-powder with a particle size of 50nm-200nm using 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% , stir well, add hydrochloric acid or sodium hydroxide to adjust the pH value of the suspension to 7-8. Then filter with suction, wash the filter cake with deionized water until no chlorine ions are detected with 0.1mol/L AgNO ₃ solution, then dry the filter cake at 120°C, and then pulverize it to obtain the natural barium salt nanometer The powdered BaSO ₄ is then ground in a ball mill for 12 hours to obtain nano-barium salt BaSO ₄ with a particle size of 100 nm. Mix the above obtained nano-barium salt with stearic acid according to the mass ratio of 9:1 to obtain the nano-barium salt coated with the stearic acid coating layer. The above-mentioned nano-barium salt containing stearic acid coating layer, composite resin material epoxy resin-oxazolidinone, and black pigment carbon black are mixed according to a mass ratio of 2:5:0.002, and placed in a ball mill for ball milling for 24h to prepare insulating coating materials.

The coating material prepared above was added to 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) is coated by a coating method, and an insulating layer with a thickness of 50 μm is obtained after drying.

Stack the positive electrode sheet, separator, and negative electrode sheet in order, so that the separator is between the positive electrode sheet and the negative electrode sheet for isolation, and then wind up to obtain the electrode assembly; place the electrode assembly on the above prepared In the outer packaging, the electrolyte is injected after drying, and the lithium-ion battery is obtained through processes such as vacuum packaging, standing still, chemical formation, and shaping.

Example 2 to Example 6

Except for adjusting relevant preparation parameters according to Table 1, the rest are the same as in Example 1. In Example 4, the nano-barium salt BaSO ₄ was replaced with BaCO ₃ known in the prior art when preparing the insulating layer.

Comparative example 1

Except that no ceramic layer, waterproof layer and insulating layer are arranged on the surface of the substrate, and a blue film with a thickness of 110 μm is coated on the surface of the substrate, the rest is the same as that of Example 1.

Comparative example 2

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

Comparative example 3

Except for adjusting relevant preparation parameters according to Table 1, the rest are the same as in Example 1.

Performance Testing:

Leakage current failure rate test:

Use an insulation tester to test the leakage current of the lithium-ion battery. One of the probes in the insulation tester is in contact with the aluminum layer in the aluminum-plastic film of the outer package, and the other probe is in contact with the insulating layer or blue film set on the outer package. Among them, 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 leakage lithium-ion battery.

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

Thickness standard deviation σ calculation:

Use a micrometer to measure the thickness of 100 lithium-ion batteries, and then calculate the standard deviation σ of the thickness of the lithium-ion batteries. The above-mentioned standard deviation is a standard deviation well known in the art.

Waterproof performance test:

Put the lithium-ion battery in a NaCl aqueous solution with a concentration of 3.5%, the water depth is 25mm, and then use the ohm gear of the multimeter to test whether there is leakage current. Place the other end 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. 100 lithium-ion batteries were tested for each example and comparative example, and the number of tested lithium-ion batteries that passed the test was recorded as the final result.

The preparation parameters and performance tests of each embodiment and comparative example are shown in Table 1.

Table 1

Note: "/" in Table 1 indicates that there is no corresponding preparation parameter or substance.

As shown in Table 1, in Example 1, the leakage current failure rate of the lithium-ion battery prepared by the outer packaging provided by the application is 0%, while in Comparative Example 1, the lithium-ion battery made of blue film coated on the outer packaging in the prior art is adopted. The leakage current failure rate of the obtained lithium-ion battery is 0.1%, indicating that the outer packaging provided by the 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 standard deviation σ of the thickness of the lithium-ion battery prepared by using the outer packaging provided by the application in Example 1 is 0.059, while in Comparative Example 1, the lithium-ion battery prepared by coating the blue film on the outer packaging in the prior art is used. The standard deviation σ of the thickness of the battery is 0.183, indicating that the use of the outer packaging provided by the application is beneficial to improve the thickness uniformity of the same batch of lithium-ion batteries. In addition, after the water resistance test, the number of passing lithium-ion batteries in Example 1 and Comparative Example 1 is 100, indicating that the outer packaging provided by the present application also has good waterproof performance.

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, waterproof layer and 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, insulation The mass ratio of nano-barium salt and composite resin material in the layer, the kind of nano-barium salt and the thickness of insulating layer can affect the performance of lithium-ion battery usually, as can be seen from embodiment 1-embodiment 6, when above-mentioned parameter is in this Within the scope of the application, the obtained lithium ion battery has good safety performance, waterproof performance and uniformity of thickness; as can be seen from Example 1-Example 6 and Comparative Example 3, when the thickness of the ceramic layer, waterproof layer and insulating layer Within the scope of the present application, the lithium-ion battery has better safety performance and waterproof performance at the same time, and the same batch of lithium-ion batteries has better thickness uniformity.

It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and within the scope of the technical solutions of the present application, embodiments that have substantially the same configuration as the technical idea and exert the same effects are included in the technical scope of the present application. In addition, without departing from the scope of the present application, various modifications conceivable by those skilled in the art are added to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application. .

Claims

A kind of outer packing, it comprises base material and the ceramic layer that is arranged on the surface of described base material successively, waterproof layer and insulating layer,

The ceramic layer includes α-alumina and/or zirconia, with a thickness of 5 μm-15 μm;

The waterproof layer includes at least one of nano-silica powder, nano-titanium dioxide powder, and nano-ceramic powder, with a thickness of 5 μm-15 μm;

The insulating layer includes nanometer barium salt and composite resin material, and the thickness is 45 μm-55 μm.
The outer package according to claim 1, wherein the ceramic layer further includes a binder, and based on the mass of the ceramic layer, the mass percentage of the binder is 0.5%-2.5%, and the binder Binders include polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene At least one of copolymers and fluorine-containing acrylate resins.
The outer package according to claim 1 or 2, wherein the nano-ceramic powder comprises alumina ceramics and/or zirconia ceramics.
The outer package according to any one of claims 1-3, wherein the particle diameters of the nano-silica powder, the nano-titanium dioxide powder and the nano-ceramic powder are each independently selected from 20nm-500nm.
The outer package according to any one of claims 1-4, wherein the mass ratio of the nano-barium salt to the composite resin material is 1:5-3:5.
The outer package according to any one of claims 1-5, wherein the nano-barium salt includes at least one of barium sulfate and barium carbonate, and the composite resin material includes epoxy resin-oxazolidinone.
The outer package according to any one of claims 1-6, wherein there is a stearic acid coating layer on the surface of the nano-barium salt particles, and the stearic acid coating layer comprises stearic acid.
A preparation method for outer packaging as described in any one of claims 1-7, comprising the following steps:

providing a ceramic layer, a waterproof layer and an insulating layer, and sequentially disposing the ceramic layer, the waterproof layer and the insulating layer on the surface of the substrate;

The ceramic layer includes α-alumina and/or zirconia, with a thickness of 5 μm-15 μm;

The waterproof layer includes at least one of nano-silica powder, nano-titanium dioxide powder, and nano-ceramic powder, with a thickness of 5 μm-15 μm;

The insulating layer includes nanometer barium salt and composite resin material, and the thickness is 45 μm-55 μm.
A secondary battery comprising the outer package according to any one of claims 1-7.
A battery module comprising the secondary battery according to claim 9.
A battery pack comprising the battery module according to claim 10.
An electrical device comprising at least one selected from the secondary battery of claim 9, the battery module of claim 10, or the battery pack of claim 11.