WO2024059996A1 - 复合膜及其制备方法、电池模块、电池包和用电装置 - Google Patents

复合膜及其制备方法、电池模块、电池包和用电装置 Download PDF

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WO2024059996A1
WO2024059996A1 PCT/CN2022/119799 CN2022119799W WO2024059996A1 WO 2024059996 A1 WO2024059996 A1 WO 2024059996A1 CN 2022119799 W CN2022119799 W CN 2022119799W WO 2024059996 A1 WO2024059996 A1 WO 2024059996A1
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film
modified
polymer resin
grafted
polymer
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PCT/CN2022/119799
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English (en)
French (fr)
Inventor
陈煜�
于晶晶
艾少华
孙成栋
张玉玺
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2022/119799 priority Critical patent/WO2024059996A1/zh
Publication of WO2024059996A1 publication Critical patent/WO2024059996A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J123/00—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J151/00—Adhesives based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
    • C09J151/06—Adhesives based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/048—Encapsulation of modules

Definitions

  • the present application relates to the field of battery technology, and in particular to a composite film and its preparation method, battery modules, battery packs and electrical devices.
  • lithium-ion batteries and sodium-ion batteries have been increasingly widely used, including in energy storage power systems such as hydraulic, thermal, wind and solar power stations, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.
  • energy storage power systems such as hydraulic, thermal, wind and solar power stations
  • power tools such as hydraulic, thermal, wind and solar power stations
  • electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields With the development of lithium-ion battery and sodium-ion battery technology, higher requirements have been put forward for their safety performance.
  • the surface of secondary batteries is generally covered with a protective film.
  • the bonding strength between the existing protective film and the secondary battery is low, resulting in a reduction in the safety performance of the secondary battery. Therefore, the safety performance of existing secondary batteries still needs to be improved.
  • This application was made in view of the above-mentioned issues, and aims to provide a composite film and a preparation method thereof, a battery module, a battery pack and a power consumption device, so as to solve the problem of low safety performance of secondary batteries.
  • an embodiment of the present application provides a method for preparing a composite film, comprising:
  • grafting a polar group on the surface of the polymer film to activate the surface of the polymer film wherein the polymer film is selected from a polyolefin film or a polyethylene-vinyl acetate film;
  • a slurry comprising a modified polymer resin grafted with polar groups is coated on the activated surface of the polymer film to form a slurry film, wherein the modified polymer resin is selected from the group consisting of modified polymer resins grafted with polar groups.
  • the modified polymer resin is selected from the group consisting of modified polymer resins grafted with polar groups.
  • the slurry film and the polymer film are heated to convert the slurry film into a modified polymer resin solid film, thereby obtaining a composite film.
  • a slurry containing a modified polymer resin grafted with polar groups is applied to the surface of an activated polymer film, and a composite film having a modified polymer resin solid film and a polymer film is obtained after heating.
  • the slurry is applied to the surface of the activated polymer film, and the surface of the polymer film is surface-modified after activation, so that the polymer film and the modified polymer resin solid film have a stronger binding force.
  • the two film layers diffuse with each other so that a gradual interface is formed between the polymer film and the modified polymer resin solid film, which not only reduces the interfacial energy between the modified polymer resin solid film and the polymer film, but also improves the composite strength between the two.
  • the composite film prepared in the present application has a polymer film with high mechanical strength and insulation performance, and the modified polymer resin solid film has a high bonding strength.
  • the polymer film and the modified polymer resin solid film are combined to form a composite film, which can better play their synergistic role of complementing each other's advantages and making up for each other's shortcomings.
  • the composite film as a whole has high mechanical strength and insulation performance, and also has good adhesion and bonding strength.
  • activating the surface of the polymer film specifically includes:
  • an activation solution includes a first graft-modified monomer with a polar group and a free radical initiator dissolved in an organic solvent;
  • the radical initiator is initiated so that the graft-modified monomer is grafted onto the surface of the polymer film.
  • the first graft-modified monomer is grafted to the surface of the polymer film by initiating a free radical initiator to activate the surface of the polymer film.
  • This activation method is simple and easy to operate.
  • the surface-grafted polar groups of the prepared polymer film are evenly dispersed, so that the modified polymer resin solid film and the modified polymer resin solid film are composite and stable.
  • the first graft modification monomer includes unsaturated carboxylic anhydride, (meth)acrylate, and optionally, maleic anhydride.
  • the above-mentioned graft-modified monomers are easily soluble in organic solvents, and are easily grafted onto the polymer film by an initiator.
  • the free radical initiator is selected from dicumyl peroxide, benzoyl peroxide, tert-butyl laurate peroxide, tert-butyl peroxybenzoate and tert-butyl peracetate. one or several kinds.
  • the above-mentioned free radical initiators are easily dissolved in organic solvents, and the above-mentioned free radical initiators are easily decomposed into free radicals by heat, which facilitates the occurrence of graft polymerization reaction.
  • the organic solvent is selected from one or more of N-methylpyrrolidone, xylene, decalin, turpentine or mineral oil.
  • the above organic solvents can fully dissolve the free radical initiator and the graft modification monomer, and can be easily volatilized and removed after heating.
  • the mass percentage of the first graft-modified monomer in the activation solution is 0.5% to 1%, optionally 0.7% to 0.8%.
  • the first graft-modified monomer in the activation solution has a certain quality and can be fully dispersed in the organic solvent and grafted to the surface of the polymer film, which also reduces the excess of the first graft. Modifying monomers are not grafted to the surface of the polymer membrane and are wasted.
  • the mass percentage of the free radical initiator in the activation solution is 0.1% to 0.5%, optionally 0.1% to 0.3%.
  • the free radical initiator has a certain quality, cooperates with the first graft-modified monomer, and initiates the free radical initiator, so that the first graft-modified monomer is fully grafted. to the surface of the polymer film.
  • initiating the free radical initiator so that the first graft-modified monomer is grafted to the surface of the polymer film specifically includes: heating the activation solution at a temperature of 120 to 150°C for 1 h to 3h.
  • the free radical initiator is initiated by heating, so that the first graft-modified monomer is grafted to the surface of the polymer film.
  • the above-mentioned grafting method is simple and the operation is controllable.
  • the polyolefin film is selected from polypropylene film or polyethylene film.
  • the above-mentioned specific optional polyolefin films enable the polymer film to have better insulating properties and mechanical properties, and the above-mentioned specific optional polyolefin films are easier to manufacture.
  • the mass concentration of the slurry is 5% to 15%, optionally 8% to 12%.
  • a suitable mass concentration of the slurry enables the slurry to be coatable and ensures the thickness of the modified polymer resin solid film subsequently formed.
  • the modified polyolefin resin is selected from modified polypropylene grafted with anhydride groups or modified polyethylene grafted with anhydride groups, optionally, selected from grafted maleic anhydride groups. Modified polypropylene or modified polyethylene grafted with maleic anhydride groups.
  • the modified polyethylene-vinyl acetate is a modified polyethylene-vinyl acetate grafted with an anhydride group, optionally, a modified polyethylene-vinyl acetate grafted with a maleic anhydride group.
  • Vinyl acetate is a modified polyethylene-vinyl acetate grafted with an anhydride group, optionally, a modified polyethylene-vinyl acetate grafted with a maleic anhydride group.
  • the specific optional modified polymer resins mentioned above are homologous to the resin forming the polymer film, which can further improve the composite strength between the polymer film and the modified polymer resin solid film.
  • the heating temperature of the slurry film and the polymer film is 50°C to 150°C, and the time is 10h to 48h, optionally 80°C to 120°C, and 20h to 30h.
  • the solvent in the slurry film can be removed by heating to form a modified polymer resin solid film, and based on the polar groups grafted on the surface of the polymer film, and the slurry film contains There are polar groups.
  • the two film layers diffuse with each other, forming a gradient interface between the polymer film and the modified polymer resin solid film, which improves the relationship between the polymer film and the modified polymer resin. Composite strength between solid films.
  • the above heating temperature can effectively reduce the degradation of the polymer film.
  • the method further comprises preparing a modified polymer resin, the preparation comprising:
  • the product is recovered from the mixed solution to obtain modified polymer resin.
  • solution grafting modification is used. This method has a lower reaction temperature, fewer side reactions, is easy to control, and has a low degree of degradation of the polymer resin.
  • the mass ratio of the polymer tree, the second graft-modified monomer and the free radical initiator in the mixed solution is 100: (1-5): (0.5-1).
  • the above-mentioned polymer resin, second graft-modified monomer and free radical initiator have a suitable mass ratio, so that the second graft-modified monomer is fully grafted to the polymer resin. surface.
  • initiating the free radical initiator to cause the graft reaction between the second graft-modified monomer and the polymer resin specifically includes: heating the mixed solution at a temperature of 100 to 140°C for 2 h to 5h.
  • the temperature of the grafting reaction is lower, effectively reducing the degree of degradation of the polymer resin.
  • the second graft-modifying monomer includes unsaturated carboxylic anhydride, (meth)acrylate, and optionally, maleic anhydride.
  • the embodiments of the present application also provide composite membranes that can be prepared by the above method.
  • the composite film provided by this application has both high mechanical strength and insulation properties, as well as high bonding strength.
  • the polymer film and the modified polymer resin solid film are combined to form a composite film, which can better utilize their advantages. Synergies that complement each other and compensate for each other’s shortcomings.
  • the polymer film is a polyethylene film
  • the modified polymer resin of the modified polymer resin solid film is modified polyethylene grafted with acid anhydride groups, optionally, grafted maleic acid Modified polyethylene with acid anhydride groups;
  • the polymer film is a polypropylene film
  • the modified polymer resin of the modified polymer resin solid film is a modified polypropylene grafted with anhydride groups, and optionally, a modified polypropylene grafted with maleic anhydride groups;
  • the polymer film is a polyethylene-vinyl acetate film
  • the modified polymer resin of the modified polymer resin solid film is modified polyethylene-vinyl acetate grafted with acid anhydride groups, Alternatively, it is modified polyethylene-vinyl acetate grafted with maleic anhydride groups.
  • the above-mentioned polymer film is composited with its homologous modified polymer resin solid film, and the composite strength is higher.
  • the thickness of the modified polymer resin solid film is 10 ⁇ m ⁇ 50 ⁇ m, optionally 10 ⁇ m ⁇ 30 ⁇ m.
  • the thickness of the modified polymer resin solid film is 10 ⁇ m to 50 ⁇ m.
  • the above-mentioned suitable thickness enables the modified polymer resin solid film to be stably bonded to the polymer film, and the composite film is applied When used in battery modules, it can ensure the bonding strength of the composite film.
  • the thickness of the modified polymer resin solid film is less than 10 ⁇ m, the finished composite film has poor adhesion.
  • the composite film is applied to the battery module, it cannot be guaranteed to be stably adhered to the secondary battery.
  • the thickness of the polymer resin solid film exceeds 50 ⁇ m, the mechanical strength of the modified polymer resin solid film is low, resulting in a reduction in the mechanical strength of the composite film.
  • the thickness of the polymer film ranges from 50 ⁇ m to 130 ⁇ m, optionally from 50 ⁇ m to 90 ⁇ m.
  • the thickness of the polymer film is 50 ⁇ m to 130 ⁇ m.
  • the above-mentioned appropriate thickness enables the polymer film composite to have certain mechanical strength and insulation properties.
  • the thickness of the polymer film is less than 50 ⁇ m, the moldability and insulation properties of the finished composite film are relatively poor.
  • the thickness of the polymer film exceeds 130 ⁇ m, the total thickness of the composite film is too thick and the flexibility will become poor. Difference.
  • Embodiments of the present application also provide a composite film, including a polymer film and a modified polymer resin solid film bonded to the surface of the polymer film.
  • the thickness of the modified polymer resin solid film is 10 ⁇ m to 50 ⁇ m.
  • the polymer film The thickness of the modified polymer resin solid film is 50 ⁇ m to 130 ⁇ m, wherein the polymer film is selected from polyolefin film or polyethylene-vinyl acetate film, and the modified polymer resin of the modified polymer resin solid film is selected from modified polymer resin grafted with polar groups. Polyolefin resin or modified polyethylene-vinyl acetate grafted with polar groups.
  • the composite film provided in the embodiment of the present application includes a polymer film and a modified polymer resin solid film.
  • the polymer film has high mechanical strength and insulation properties, and the modified polymer resin solid film has high bonding strength.
  • the polymer film and the modified polymer resin solid film are composited to form a composite film, which can better play their synergistic effect of complementing each other's advantages and making up for each other's shortcomings.
  • the composite film as a whole has higher structural stability, and also has better conformability and bonding strength.
  • Embodiments of the present application also provide a battery module, including a secondary battery and a composite film.
  • the composite film covers at least part of the secondary battery, and the modified polymer resin solid film in the composite film adheres to the secondary battery.
  • the composite membrane is a composite membrane prepared by the above method or the above composite membrane.
  • the composite film is directly adhered to the secondary battery through the adhesiveness of the modified polymer resin solid film without using heat-sensitive glue for bonding, and the composite film and the secondary battery are The bonding strength is high, which effectively reduces the peeling off of the composite film and the secondary battery.
  • Embodiments of the present application also provide a method for preparing a battery module, which includes: coating a composite film on the surface of a secondary battery by hot pressing to obtain a battery module, wherein the modified polymer resin solid film in the composite film Adhere to secondary batteries.
  • the composite film is coated on the surface of the secondary battery through hot pressing.
  • the preparation method is simple, improves production efficiency, and the hot pressing method can tightly fit the composite film on the two batteries.
  • the surface of the secondary battery ensures that the composite film and the secondary battery are tightly covered.
  • the composite film of this application has low bonding strength at room temperature, making it easy to install and film.
  • the bonding strength of the composite film increases and is higher than conventional heat-sensitive adhesives, and can be stably Coated on the surface of the secondary battery.
  • the temperature of the hot pressing method is 90°C to 180°C, optionally 100°C to 150°C.
  • the temperature of the hot pressing method is determined based on the modified polymer resin solid film. At a certain temperature, the bonding strength of the modified polymer resin solid film can be guaranteed and the polymer can be reduced. Defects in membrane degradation.
  • the pressure of the hot pressing method is 0.1 MPa to 5 MPa, and optionally 0.5 MPa to 5 MPa.
  • the pressure and temperature of the hot pressing method are matched to make the composite film tightly adhere to the surface of the secondary battery and ensure that the composite film has a certain thickness, so that the composite film has high mechanical strength. strength.
  • the time of the hot pressing method is 1s to 10s, optionally 3s to 5s.
  • appropriate hot pressing time ensures that the composite film has a certain thickness, so that the composite film has high mechanical strength.
  • the method before the composite film is compounded on the surface of the secondary battery, the method further includes: sandblasting and then acidifying the surface of the secondary battery.
  • performing activation treatment on the surface of the secondary battery can remove impurities and oxide films on the surface of the secondary battery and improve the cleanliness of the surface of the secondary battery. , and make the surface of the secondary battery have a certain roughness, so that the mechanical properties of the surface of the secondary battery are improved, thereby increasing the adhesion between the surface of the secondary battery and the composite film, and prolonging the durability of the composite film .
  • the present application provides a battery pack, including the above-mentioned battery module or the battery module obtained by the above-mentioned method.
  • the present application provides an electrical device, which includes a battery module selected from the above, a battery module obtained by the above method, or a battery pack.
  • Figure 1 shows a flow chart of a method for preparing a composite membrane according to an embodiment of the present application.
  • Figure 2 shows a flow chart of an exemplary process for activating the surface of a polymer film in a method of preparing a composite film.
  • FIG. 3 shows a flow chart of an exemplary process of forming a modified polymer resin in a method of preparing a composite membrane.
  • FIG. 4 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 5 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 4 .
  • Figure 6 is a schematic diagram of a battery module according to an embodiment of the present application.
  • Figure 7 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 8 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 7 .
  • FIG. 9 is a schematic diagram of a power consumption device using a secondary battery as a power source according to an embodiment of the present application.
  • Ranges disclosed herein are defined in terms of lower and upper limits. 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 of the endpoints, and may be arbitrarily combined, that is, 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, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • 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.
  • the numerical range “0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations.
  • a certain parameter is an integer ⁇ 2
  • 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.
  • step (c) means that step (c) may be added to the method in any order.
  • 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), etc.
  • condition "A or B” is satisfied by any of the following conditions: 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 surface of the secondary battery is generally covered with a protective film with insulating properties, and the protective film and the secondary battery are bonded by glue.
  • the glue method makes the protective film and the secondary battery Low connection strength and uneven glue application will also lead to inconsistent bonding strength of the protective film, reducing the protective performance of the protective film and prone to the risk of short circuit.
  • this application provides a composite film, which includes a polymer film and a modified polymer resin solid film.
  • the polymer film has high mechanical strength and insulation properties
  • the modified polymer resin solid film has With higher bonding strength, the polymer film and the modified polymer resin solid film are combined to form a composite film, which can better leverage their complementary advantages and compensate for each other's shortcomings.
  • the composite film as a whole It has high structural stability, and also has good fit and bonding strength.
  • FIG. 1 shows a flow chart of a method for preparing a composite membrane according to an embodiment of the present application.
  • the method for preparing a composite membrane includes:
  • the polymer film is selected from polyolefin film or polyethylene-vinyl acetate film;
  • the modified polymer resin is selected from modified polyolefin resin grafted with polar groups or modified polyethylene-vinyl acetate grafted with polar groups;
  • the method for preparing a composite membrane of the present application is to apply a slurry containing a modified polymer resin grafted with polar groups on the surface of an activated polymer membrane, and then heat it to obtain a modified polymer resin.
  • Composite membrane of solid membrane and polymer membrane without intending to be limited to any theory or explanation, a slurry containing a modified polymer resin grafted with polar groups is coated on the surface of the activated polymer film. After the surface activation of the polymer film, surface Modification allows the polymer film to have stronger binding force with the modified polymer resin solid film.
  • the two film layers diffuse with each other, causing the polymer film to interact with the modified polymer.
  • a gradient interface is formed between the resin solid films, which not only reduces the interface energy between the modified polymer resin solid film and the polymer film, but also increases the composite strength between the two.
  • the polymer film has high mechanical strength and insulation properties
  • the modified polymer resin solid film has high bonding strength
  • the polymer film is composited with the modified polymer resin solid film.
  • step S1 by grafting polar groups on the surface of the polymer film selected from the group consisting of polyolefin films or polyethylene-vinyl acetate films, the polarity of the surface of the polymer film can be increased, Thereby realizing the functionalization of the polymer membrane surface and improving the activity of the polymer membrane surface.
  • the grafted polar group comes from unsaturated carboxylic acid anhydride and unsaturated carboxylic acid ester.
  • the polyolefin film is a film formed by using polyolefin resin as a film-forming matrix.
  • polyolefin resin refers to a homopolymer or copolymer formed by the polymerization of olefin monomers, and includes blends of two or more polyolefins.
  • the polyethylene-vinyl acetate film is a film formed using polyethylene-vinyl acetate resin as a film-forming matrix.
  • polyethylene-vinyl acetate (EVA) is a copolymer of ethylene and vinyl acetate, wherein the mass fraction of vinyl acetate (VA) is less than or equal to 30%, optionally less than or equal to 20%, Optional is less than or equal to 15%, optionally is less than or equal to 10%.
  • step S2 the slurry containing the modified polymer resin grafted with polar groups is coatable and can be stably attached to the activated surface of the polymer film after coating.
  • the slurry coating method is selected from one of gravure, microgravure, screen printing, roller printing, electrospraying, transfer coating or extrusion coating.
  • step S3 the slurry film and the polymer film are heated.
  • heating can remove the solvent in the slurry film to form a modified polymer resin solid film.
  • the slurry film contains polar groups.
  • the polymer film and the slurry film diffuse into each other, causing the polymer film to be modified.
  • a gradient interface is formed between the polymer resin solid films, which improves the composite strength between the two.
  • Figure 2 shows a flow chart of an exemplary process for activating the surface of a polymer film in a method of preparing a composite film.
  • activating the surface of the polymer film in step S1 specifically includes:
  • Step S11 Provide an activation solution, wherein the activation solution includes a first graft-modified monomer with a polar group and a free radical initiator dissolved in an organic solvent;
  • Step S12 When the surface of the polymer film is brought into contact with the activation solution, a free radical initiator is initiated so that the first graft-modified monomer is grafted to the surface of the polymer film.
  • step S11 of the present application the organic solvent, the first graft-modified monomer with polar groups and the free radical initiator are mixed to obtain an activation liquid. Under sufficient stirring conditions, the first graft-modified monomer with polar groups and the free radical initiator are fully dispersed in the organic solvent.
  • step S12 of this application the first graft-modified monomer is grafted to the surface of the polymer film through the graft polymerization reaction initiated by the free radical initiator to modify the surface of the polymer film, thereby Improve the subsequent bonding strength with the modified polymer resin solid film.
  • the means of initiating free radical initiation include chemical methods or radiation methods.
  • the method of initiating free radical initiation includes heating.
  • the first graft-modified monomer is grafted to the surface of the polymer film by initiating a free radical initiator to activate the surface of the polymer film.
  • This activation method is simple and easy to operate.
  • the surface grafted polar groups of the prepared polymer film are evenly dispersed, so that the modified polymer resin solid film and the modified polymer resin solid film are composite and stable.
  • the first graft-modifying monomer includes unsaturated carboxylic anhydride, (meth)acrylate.
  • the graft modifying monomer includes maleic anhydride.
  • the above-mentioned first graft-modified monomers are easily soluble in organic solvents, and are easily grafted onto the polymer film by an initiator.
  • the free radical initiator is selected from one or more of dicumyl peroxide, benzoyl peroxide, t-butyl perlaurate, t-butyl perbenzoate, and t-butyl peracetate.
  • the above-mentioned free radical initiators are easily soluble in organic solvents, and the above-mentioned free radical initiators are easily decomposed by heat to form free radicals, which facilitates the occurrence of graft polymerization reaction.
  • the organic solvent is selected from one or more of N-methylpyrrolidone, xylene, decalin, turpentine or mineral oil.
  • the above-mentioned organic solvents can fully dissolve the free radical initiator and the first graft modification monomer, and can be easily volatilized and removed after heating.
  • the mass percentage of the first graft-modified monomer in the activation solution is 0.5% to 1%.
  • the mass percentage of the first graft-modified monomer in the activation solution is 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1% or any two of the above. other ranges composed of endpoints.
  • the mass percentage of the first graft-modified monomer in the activation solution is 0.7% to 0.8%.
  • the first graft-modified monomer in the activation solution has a certain quality and can be fully dispersed in the organic solvent and grafted to the surface of the polymer film, which also reduces the excess of the first graft. Modifying monomers are not grafted to the surface of the polymer membrane and are wasted.
  • the mass percentage of the free radical initiator in the activation solution is 0.1% to 0.5%.
  • the mass percentage of the free radical initiator in the activation solution is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, within other ranges composed of any two endpoints mentioned above. .
  • the mass percentage of the free radical initiator in the activation solution is 0.1% to 0.3%.
  • the free radical initiator has a certain mass, cooperates with the first graft modification monomer, and causes the first graft modification monomer to be grafted onto the surface of the polymer film by initiating the free radical initiator.
  • initiating the free radical initiator to graft the first graft-modified monomer to the surface of the polymer film specifically includes: heating the activation solution at a temperature of 120°C to 150°C for 1h to 3h. .
  • the free radical initiator is initiated such that the temperature at which the first graft-modified monomer is grafted onto the surface of the polymer film is 120°C, 121°C, 122°C, 123°C, 124°C , 125°C, 126°C, 127°C, 128°C, 129°C, 130°C, 131°C, 132°C, 133°C, 134°C, 135°C, 136°C, 137°C, 138°C, 139°C, 140°C, 141 °C, 142°C, 143°C, 144°C, 145°C, 146°C, 147°C, 148°C, 149°C, 150°C or other ranges composed of any two of the above endpoints.
  • the heating time for initiating the free radical initiator so that the first grafted modified monomer is grafted to the surface of the polymer film is 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h, 3h or in other ranges composed of any two endpoints mentioned above.
  • the free radical initiator is initiated by heating, so that the first graft-modified monomer is grafted to the surface of the polymer film.
  • the above-mentioned grafting method is simple and the operation is controllable.
  • the polyolefin film is selected from polypropylene film or polyethylene film.
  • the polypropylene film is a film formed by using polypropylene resin as a film-forming matrix.
  • polypropylene resins include homopolymers of propylene and copolymers of propylene with small amounts of olefin comonomers.
  • the polyethylene film is a film formed by using polyethylene resin as a film-forming matrix.
  • polyethylene resins include homopolymers of ethylene and copolymers of ethylene with small amounts of olefin comonomers. Examples of polyethylene resins include, but are not limited to, high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), polyolefin elastomer (POE).
  • HDPE high density polyethylene
  • LDPE low density polyethylene
  • LLDPE linear low density polyethylene
  • POE polyolefin elastomer
  • the above-mentioned specifically selected polyolefin films can make the polymer film have better insulation properties and mechanical properties, and the above-mentioned specifically selected polyolefin films are easier to prepare.
  • the mass concentration of the slurry is 5% to 15%.
  • the mass concentration of the slurry is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or in other ranges formed by any two endpoints mentioned above.
  • the mass concentration of the slurry is 8% to 13%.
  • a suitable mass concentration of the slurry enables the slurry to be coatable and ensures the thickness of the modified polymer resin solid film subsequently formed.
  • the modified polyolefin resin is selected from modified polypropylene grafted with anhydride groups or modified polyethylene grafted with anhydride groups.
  • the modified polyolefin resin is selected from modified polypropylene grafted with maleic anhydride groups or modified polyethylene grafted with maleic anhydride groups.
  • the modified polyethylene-vinyl acetate is modified polyethylene-vinyl acetate grafted with anhydride groups.
  • the modified polyethylene-vinyl acetate is modified polyethylene-vinyl acetate grafted with maleic anhydride groups.
  • the specific optional modified polymer resins mentioned above are homologous to the resin forming the polymer film, which can further improve the composite strength between the polymer film and the modified polymer resin solid film.
  • the heating temperature of the slurry film and the polymer film is 50°C to 150°C, and the heating time is 10h to 48h.
  • the heating temperature of the slurry film and the polymer film is 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C , 150°C or other ranges consisting of any two of the above endpoints.
  • the heating temperature for heating the slurry film and the polymer film is 80°C to 130°C.
  • the heating time for heating the slurry film and the polymer film is 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h , 25h, 26h, 27h, 28h, 29h, 30h, 31h, 32h, 33h, 34h, 35h, 36h, 37h, 38h, 39h, 40h, 41h, 42h, 43h, 44h, 45h, 46h, 47h, 48h or at Any other range consisting of any two endpoints mentioned above.
  • the heating time for heating the slurry film and the polymer film is 20h to 30h.
  • the solvent in the slurry film can be removed by heating to form a solid film of modified polymer resin.
  • the two film layers mutually diffuse each other to form a gradient interface between the polymer film and the modified polymer resin solid film, which improves the composite strength between the polymer film and the modified polymer resin solid film.
  • the above heating temperature can effectively reduce the degradation of the polymer film.
  • FIG. 3 shows a flow chart of an exemplary process of forming a modified polymer resin in a method of preparing a composite membrane.
  • a modified polymer resin is further prepared, and the preparation includes:
  • solution grafting modification is used. This method has a lower reaction temperature, fewer side reactions, is easy to control, and has a low degree of degradation of the polymer resin.
  • the mass ratio of the polymer tree, the second graft-modified monomer and the free radical initiator in the mixed solution is 100: (1-5): (0.5-1).
  • the mass ratio of the polymer resin, the second graft-modified monomer and the free radical initiator in the mixed solution is 100:3:0.6.
  • the polymer resin, the second graft modification monomer and the free radical initiator have a suitable mass ratio to achieve surface modification of the polymer resin.
  • initiating the free radical initiator to cause a graft reaction between the second graft-modified monomer and the polymer resin specifically includes: heating the mixed solution at a temperature of 100°C to 140°C for 3h to 5h. .
  • the temperature of the grafting reaction is lower, effectively reducing the degree of degradation of the polymer resin.
  • the second graft-modifying monomer includes unsaturated carboxylic anhydride, (meth)acrylate.
  • the second graft-modifying monomer includes maleic anhydride.
  • Embodiments of the present application also provide composite membranes that can be prepared by any embodiment of the above method.
  • the composite film provided by this application has not only high mechanical strength, insulation performance, but also high bonding strength.
  • the polymer film and the modified polymer resin solid film are combined to form a composite film, which can better utilize their advantages. Synergies that complement each other and compensate for each other’s shortcomings.
  • the polymer film is a polyethylene film
  • the modified polymer resin of the modified polymer resin solid film is modified polyethylene grafted with acid anhydride groups.
  • the modified polymer resin is modified polyethylene grafted with maleic anhydride groups
  • the polymer film is a polypropylene film
  • the modified polymer resin of the modified polymer resin solid film is modified polypropylene grafted with acid anhydride groups.
  • the modified polymer resin is modified polypropylene grafted with maleic anhydride groups.
  • the polymer film is a polyethylene-vinyl acetate film
  • the modified polymer resin of the modified polymer resin solid film is modified polyethylene-vinyl acetate grafted with acid anhydride groups.
  • the modified polymer resin is modified polyethylene-vinyl acetate grafted with maleic anhydride groups.
  • the above-mentioned polymer film is composited with its homologous modified polymer resin solid film, and the composite strength is higher.
  • the thickness of the modified polymer resin solid film ranges from 10 ⁇ m to 50 ⁇ m.
  • the thickness of the modified polymer resin solid film is 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, 40 ⁇ m, 45 ⁇ m, 50 ⁇ m or other ranges consisting of any two of the above endpoints.
  • the thickness of the modified polymer resin solid film is 10 ⁇ m to 30 ⁇ m.
  • the thickness of the modified polymer resin solid film is 10 ⁇ m to 50 ⁇ m.
  • the above-mentioned suitable thickness enables the modified polymer resin solid film to be stably bonded to the polymer film, and the composite film is applied When used in battery modules, it can ensure the bonding strength of the composite film.
  • the thickness of the modified polymer resin solid film is less than 10 ⁇ m, the finished composite film has poor adhesion.
  • the composite film is applied to the battery module, it cannot be guaranteed to be stably adhered to the secondary battery.
  • the thickness of the polymer resin solid film exceeds 50 ⁇ m, due to the low mechanical strength of the modified polymer resin solid film, the overall mechanical strength of the composite film is reduced.
  • the polymer film has a thickness of 50 ⁇ m to 130 ⁇ m.
  • the thickness of the polymer film is 50 ⁇ m, 60 ⁇ m, 70 ⁇ m, 80 ⁇ m, 90 ⁇ m, 100 ⁇ m, 110 ⁇ m, 120 ⁇ m, 130 ⁇ m, or other ranges consisting of any two of the above endpoints.
  • the thickness of the polymer film is 50 ⁇ m to 90 ⁇ m.
  • the thickness of the polymer film is 50 ⁇ m to 130 ⁇ m.
  • the above-mentioned appropriate thickness enables the polymer film composite to have certain mechanical strength and insulation properties.
  • the thickness of the polymer film is less than 50 ⁇ m, the moldability and insulation properties of the finished composite film are relatively poor.
  • the thickness of the polymer film exceeds 120 ⁇ m, the total thickness of the composite film is too thick and the flexibility will become poor. Difference.
  • a composite film including a polymer film and a modified polymer resin solid film bonded to the surface of the polymer film.
  • the thickness of the modified polymer resin solid film is 10 ⁇ m to 50 ⁇ m.
  • the thickness of the polymer film is 50 ⁇ m to 130 ⁇ m, wherein the polymer film is selected from polyolefin film or polyethylene-vinyl acetate film, and the modified polymer resin of the modified polymer resin solid film is selected from the group consisting of grafted polar groups. modified polyolefin resin or modified polyethylene-vinyl acetate grafted with polar groups. .
  • the polymer film of the present application is used as an insulating protective film for secondary batteries due to its excellent transparency, mechanical properties, electrical properties, etc.
  • the polymer film is prepared from a polymer resin.
  • the thickness of the polymer film in this application is 50 ⁇ m to 130 ⁇ m.
  • the above-mentioned appropriate thickness enables the polymer film composite to have certain mechanical strength and insulation properties.
  • the thickness of the polymer film is less than 50 ⁇ m, the moldability and insulation properties of the finished composite film are relatively poor.
  • the thickness of the polymer film exceeds 130 ⁇ m, the total thickness of the composite film is too thick and the flexibility will become poor. Difference.
  • the modified polymer resin solid film of the present application is grafted with polar groups and has high bonding strength.
  • the modified polymer resin solid film can fit tightly onto the surface of the polymer film.
  • the modified polymer resin solid film and the polymer film are two similar or compatible surfaces. When the two are in contact, a stable connection can be formed between the polymer film and the modified polymer resin solid film due to the small interfacial energy.
  • the thickness of the modified polymer resin solid film of the present application is 10 ⁇ m to 50 ⁇ m.
  • the above-mentioned appropriate thickness enables the modified polymer resin solid film to be stably bonded to the polymer film, and when the composite film is applied to a battery module, it can Ensure the bonding strength of the composite film.
  • the thickness of the modified polymer resin solid film is less than 10 ⁇ m, the finished composite film has poor adhesion.
  • the composite film is applied to the battery module, it cannot be guaranteed to be stably adhered to the secondary battery.
  • the thickness of the polymer resin solid film exceeds 50 ⁇ m, the mechanical strength of the modified polymer resin solid film is low, resulting in a reduction in the mechanical strength of the composite film.
  • the composite film provided by this application includes a polymer film and a modified polymer resin solid film.
  • the polymer film has high mechanical strength and insulation properties.
  • the modified polymer resin solid film has high bonding strength.
  • the polymer film Combined with a modified polymer resin solid film to form a composite film, they can better leverage their complementary advantages and make up for each other's shortcomings. Compared with a single protective film, the composite film as a whole has higher structural stability and also has a higher structural stability. Has good fit and bonding strength.
  • FIG. 4 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 5 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 4 .
  • Figure 6 is a schematic diagram of a battery module according to an embodiment of the present application.
  • Figure 7 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 8 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 7 .
  • FIG. 9 is a schematic diagram of a power consumption device using a secondary battery as a power source according to an embodiment of the present application.
  • the battery module includes a secondary battery and a composite film, the composite film covers at least part of the secondary battery, and the modified polymer resin solid film in the composite film adheres to the secondary battery, wherein the composite film is prepared by a method of composite membrane or of composite membrane.
  • the battery module of this application can directly adhere the composite film to the secondary battery through the modified polymer resin solid film based on the adhesiveness of the composite film itself. There is no need to use heat-sensitive adhesive for bonding, and the composite film and the secondary battery The bonding strength of the secondary battery is high, which effectively reduces the peeling off of the composite film and the secondary battery.
  • Methods for preparing battery modules include:
  • the composite film is coated on the surface of the secondary battery by hot pressing to obtain a battery module, in which the modified polymer resin solid film in the composite film adheres to the secondary battery.
  • the method for preparing a battery module of the present application is to coat the composite film on the surface of a secondary battery by hot pressing.
  • the preparation method is simple and improves production efficiency.
  • the hot pressing method can closely fit the composite film on the surface of the secondary battery to ensure that the composite film and the secondary battery are tightly coated.
  • the composite film of the present application has a low bonding strength at room temperature, which is convenient for installation and film pasting. After hot pressing, the bonding strength of the composite film increases and is higher than that of conventional thermal adhesives, and can be stably coated on the surface of the secondary battery.
  • the temperature of the hot pressing method is 90°C to 180°C.
  • the temperature of the hot pressing method is 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C or in other ranges formed by any two of the above endpoints.
  • the thickness of the polymer film is 100°C to 150°C.
  • the temperature of the hot pressing method is determined based on the modified polymer resin solid film. At a certain temperature, the bonding strength of the modified polymer resin solid film can be guaranteed and the polymer can be reduced. degree of membrane degradation.
  • the pressure of the hot pressing method is 0.1 MPa to 5 MPa.
  • the pressure of the hot pressing method is 0.1MPa, 0.5MPa, 1MPa, 1.5MPa, 2MPa, 2.5MPa, 3MPa, 3.5MPa, 4MPa, 4.5MPa, 5MPa or any two of the above. other ranges composed of endpoints.
  • the pressure of the hot pressing method is 0.5MPa ⁇ 5MPa;
  • the pressure and temperature of the hot pressing method are matched to make the composite film tightly adhere to the surface of the secondary battery and ensure that the composite film has a certain thickness, so that the composite film has high mechanical strength. strength and shear strength.
  • the time of the hot pressing method is 1s to 10s.
  • the time of the hot pressing method is 1s, 2s, 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s or within other ranges composed of any two endpoints mentioned above.
  • the time of the hot pressing method is 3 to 5 seconds.
  • appropriate hot pressing time ensures that the composite film has a certain thickness, so that the composite film has high mechanical strength and shear strength.
  • the method before laminating the composite film on the surface of the secondary battery, the method further includes: sandblasting and then acidifying the surface of the secondary battery.
  • the sandblasting process uses sand with a particle size of 2mm and a compressed air pressure of 0.5MPa.
  • the types of sand particles are stainless steel sand, zircon sand or emery, etc.
  • the acidification treatment uses hydrochloric acid, sulfuric acid or acetic acid for pickling.
  • performing activation treatment on the surface of the secondary battery can remove impurities and oxide films on the surface of the secondary battery and improve the cleanliness of the surface of the secondary battery. , and make the surface of the secondary battery have a certain roughness, so that the mechanical properties of the surface of the secondary battery are improved, thereby increasing the adhesion between the surface of the secondary battery and the composite film, and prolonging the durability of the composite film .
  • a secondary battery typically includes a positive electrode plate, a negative electrode plate, an electrolyte and a separator.
  • active ions are inserted and detached back and forth between the positive and negative electrodes.
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the isolation film is placed between the positive electrode piece and the negative electrode piece. It mainly prevents the positive and negative electrodes from short-circuiting and allows ions to pass through.
  • the positive electrode current collector has two surfaces opposite in its own thickness direction, and the positive electrode active material layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • the metal foil aluminum foil can 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 base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the cathode active material may be a cathode active material known in the art for batteries.
  • the cathode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials of batteries can also be used. Only one type of these positive electrode active materials may be used alone, or two or more types may be used in combination.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 3 ), lithium nickel oxides (such as LiNiO 3 ), lithium manganese oxides (such as LiMnO 3 , LiMn 3 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 3 (also referred to as NCM 333 ), LiNi 0.5 Co 0.3 Mn 0.3 O 3 (can also be abbreviated to NCM 533 ), LiNi 0.5 Co 0.35 Mn 0.35 O 3 (can also be abbreviated to NCM 311 ), LiNi 0.6 Co 0.3 Mn 0.3 O 3 (can also be abbreviated to NCM 633 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 3 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as Li Li
  • the olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon. At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • composites of lithium iron phosphate and carbon such as LiMnPO 4
  • LiMnPO 4 lithium manganese phosphate and carbon.
  • At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • the cathode active material layer may further include a conductive agent to improve the conductive performance of the cathode.
  • a conductive agent to improve the conductive performance of the cathode.
  • the conductive agent can be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene and carbon nanofibers.
  • the positive active material layer may further include a binder to firmly bond the positive active material and optional conductive agent to the positive current collector.
  • a binder to firmly bond the positive active material and optional conductive agent to the positive current collector.
  • the binder may be polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyvinyl alcohol (PVA), ethylene-vinyl acetate copolymer (EVA), styrene-butadiene At least one of rubber (SBR), carboxymethyl cellulose (CMC), sodium alginate (SA), polymethacrylic acid (PMA) and carboxymethyl chitosan (CMCS).
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PAA polyacrylic acid
  • PVA polyvinyl alcohol
  • EVA ethylene-vinyl acetate copolymer
  • SBR carboxymethyl cellulose
  • SA
  • the positive electrode current collector can be a conductive carbon sheet, a metal foil, a carbon-coated metal foil, a porous metal plate or a composite current collector, wherein the conductive carbon material of the conductive carbon sheet can be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene and carbon nanofibers, and the metal material of the metal foil, the carbon-coated metal foil and the porous metal plate can be independently selected from at least one of copper, aluminum, nickel and stainless steel.
  • the composite current collector can be a composite current collector formed by a metal foil and a polymer base film.
  • the positive electrode current collector is, for example, one or more of copper foil, aluminum foil, nickel foil, stainless steel foil, stainless steel mesh and carbon-coated aluminum foil, preferably aluminum foil.
  • the above-mentioned positive electrode sheet can be prepared according to conventional methods in the art.
  • the positive electrode active material and optional conductive agent and binder are dispersed in a solvent (such as N-methylpyrrolidone, referred to as NMP) to form a uniform positive electrode slurry, and the positive electrode slurry is coated on the positive electrode current collector , after drying and cold pressing, the positive electrode piece is obtained.
  • a solvent such as N-methylpyrrolidone, referred to as NMP
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material.
  • the negative electrode active material is a negative electrode active material prepared by the preparation method of the first aspect of the present application or a negative electrode active material of the present application. Therefore, the above description of the embodiment of the negative electrode active material according to the present application is also applicable to the negative electrode active material in the secondary battery, and the same content is not repeated here.
  • the negative electrode current collector has two surfaces opposite in its own thickness direction, and the negative electrode active material layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • 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 base material.
  • the composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative active material may be a negative active material known in the art for batteries.
  • the negative 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, and the like.
  • 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.
  • the present application is not limited to these materials, and other traditional materials that can be used as battery negative electrode active materials can also be used. Only one type of these negative electrode active materials may be used alone, or two or more types may be used in combination.
  • the negative electrode active material layer may further include a binder.
  • the 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).
  • the negative active material layer optionally further includes a conductive agent.
  • the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative active material layer optionally also includes other auxiliaries, such as thickeners (such as sodium carboxymethyl cellulose (CMC-Na)) and the like.
  • auxiliaries such as thickeners (such as sodium carboxymethyl cellulose (CMC-Na)) and the like.
  • the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative active materials, conductive agents, binders and any other components 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 piece can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays a role in conducting ions between the positive electrode piece and the negative electrode piece.
  • the type of electrolyte in this application can be selected according to needs.
  • the electrolyte can be liquid, gel, or completely solid.
  • the electrolyte is an electrolyte solution.
  • the electrolyte solution includes electrolyte salts and solvents.
  • the electrolyte salt may be one or more of NaPF 6 , NaClO 4 , NaBF 4 , KPF 6 , KClO 4 , KBF 4 , LiPF 6 , LiClO 4 , LiBF 4 , Zn(PF 6 ) 3 , Zn(ClO 4 ) 3 , and Zn(BF 4 ) 3 .
  • the electrolyte salt can be selected from one or more of NaPF 6 , NaClO 4 , and NaBF 4 .
  • the solvent may be selected from the group consisting of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl 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.
  • the electrolyte optionally further includes additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.
  • isolation membrane there is no particular restriction on the type of isolation membrane, and any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.
  • 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 film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
  • the positive electrode piece, the negative electrode piece, and the separator film can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • FIG. 4 shows a square-structured secondary battery 5 as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can cover the opening to close the accommodation cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 53 through a winding process or a lamination process.
  • the electrode assembly 53 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 53 .
  • the number of electrode assemblies 53 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • secondary batteries can be assembled into battery modules, and the number of secondary batteries contained in the battery module can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery module.
  • FIG. 6 shows a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having an accommodation space in which a plurality of secondary batteries 5 are accommodated.
  • the above-mentioned battery modules can also be assembled into a battery pack.
  • the number of battery modules contained in the battery pack can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box 3 and a lower box 3 .
  • the upper box 3 can be covered with the lower box 3 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.
  • This application also provides an electrical device, which includes the battery module or battery pack provided by this application.
  • the battery module or battery pack can be used as a power source for the electrical device or as an energy storage unit for the electrical device.
  • the electric 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, and electric golf carts). , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.
  • a battery module or battery pack can be selected according to its usage requirements.
  • FIG. 9 shows an electrical device as an example.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc.
  • a battery pack or battery module can be used.
  • the device may be a mobile phone, a tablet, a laptop, etc.
  • This device is usually required to be thin and light, and secondary batteries can be used as power sources.
  • the positive active material conductive agent Super P
  • binder polyvinylidene fluoride PVDF
  • NMP binder polyvinylidene fluoride
  • the viscosity of the positive electrode slurry is 6200 mPas and the positive electrode slurry will not gel, layer or settle within 48 hours; the solid content of the positive electrode slurry is 70%; the positive electrode slurry is coated on the positive electrode current collector aluminum foil On the surface, after drying and cold pressing, the positive electrode piece is obtained.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • DMC dimethyl carbonate
  • the positive electrode sheet, the separator, and the negative electrode sheet are stacked and wound in order to obtain an electrode assembly, the electrode assembly is placed in an outer package, the prepared electrolyte is added, and after packaging, standing, formation, aging and other processes, a secondary battery is obtained.
  • the acid anhydride-containing polypropylene with a mass concentration of 10% is The slurry of modified polypropylene is blade-coated on the activated surface of the polypropylene film with a thickness of 100 ⁇ m to form a slurry film;
  • the surface of the aluminum shell of the secondary battery is sandblasted with stainless steel sand with a particle size of 2mm and powered by 0.5MPa compressed air. Then, a 5wt% hydrochloric acid solution is used to wipe the surface of the aluminum shell to remove stains, and then cleaned with deionized water and dried at 80°C. Dry with downward blast and set aside.
  • the composite film is coated on the surface of the aluminum shell using a coating machine, and hot-pressed at 0.5MPa pressure and 150°C for 5 seconds to obtain a battery module, in which the acid anhydride-modified polypropylene film adheres to the surface of the aluminum shell, and the acid anhydride-modified polypropylene film
  • the thickness of the acrylic film is 20 ⁇ m and the thickness of the polypropylene film is 80 ⁇ m.
  • Examples 2 to 5 and Comparative Examples 1 to 3 are similar to those of Example 1 (the polyolefin films are the same and the hot pressing conditions are the same), except that the surface of the polymer film is not activated, and the components of the activation solution are modified polymer resins.
  • the relevant parameters of Examples 1 to 5 and Comparative Examples 1 to 3 are shown in Table 1.
  • Example 6 to 13 and Comparative Examples 4 to 11 are similar to those of Example 1, except that the polymer film is selected from one of a polyethylene film, a polypropylene film or a polyethylene-vinyl acetate film, the modified polymer resin solid film is selected from an anhydride-modified polyethylene film, an anhydride-modified polypropylene film or an anhydride-modified polyethylene-vinyl acetate film, the thickness of the polymer film, and the thickness of the modified polymer resin solid film.
  • Table 2 The relevant parameters of Examples 6 to 13 and Comparative Examples 4 to 11 are shown in Table 2.
  • Examples 14 to 19 and Comparative Examples 12 to 16 are similar to those of Example 1, except for: hot pressing temperature, hot pressing time and hot pressing pressure.
  • the relevant parameters of Examples 14 to 19 and Comparative Examples 12 to 16 are shown in Table 3.
  • the protective film is adhered to the surface of the 150 ⁇ 100mm aluminum plate and placed on a horizontal rigid plane.
  • the slurry is coated on the surface of the activated polymer film.
  • surface modification occurs, so that the polymer film and the modified polyolefin polymer resin solid film have a stronger binding force.
  • the surface-activated grafted polar groups of the polymer film and the grafted polar groups contained in the slurry film diffuse with each other during the heating process, making the polymer film and the modified polymer resin solid A gradient interface is formed between the films, which not only reduces the interface energy between the modified polymer resin solid film and the polymer film, but also increases the composite strength between the two.
  • the obtained composite film has not only high mechanical strength, insulation performance and shear strength, but also high bonding strength.
  • the polymer film and the modified polymer resin solid film are combined to form a composite film, which can better utilize them.
  • the polymer film is composited with its homologous modified polymer resin solid film, and the composite strength is higher.
  • the thickness of the modified polymer resin solid film is 10 ⁇ m to 50 ⁇ m.
  • the above suitable thickness enables the modified polymer resin solid film to be stably bonded to the polymer film, and the composite film is used in When used as a battery module, the bonding strength of the composite film can be ensured.
  • the thickness of the polymer film is 50 ⁇ m to 130 ⁇ m. The above-mentioned appropriate thickness enables the polymer film composite to have certain mechanical strength and insulation properties.
  • the composite film is coated on the surface of the secondary battery through hot pressing.
  • the preparation method is simple and improves production efficiency.
  • the hot pressing method can closely adhere the composite film to the surface of the secondary battery. , ensuring that the composite film and the secondary battery are tightly covered.
  • the composite film of this application has low bonding strength at room temperature, making it easy to install and film.
  • the bonding strength of the composite film increases and is higher than conventional heat-sensitive adhesives, and can be stably Coated on the surface of the secondary battery.

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  • Condensed Matter Physics & Semiconductors (AREA)
  • Electromagnetism (AREA)
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Abstract

本申请实施例提供一种复合膜及其制备方法、电池模块、电池包和用电装置。本申请的制备复合膜的方法，包括：将聚合物膜的表面接枝极性基团以使所述聚合物膜的表面活化，其中，所述聚合物膜选自聚烯烃膜或聚乙烯-醋酸乙烯酯膜；将包含接枝有极性基团的改性聚合物树脂的浆料涂布于所述聚合物膜的经活化的表面，以形成浆料膜，其中，所述改性聚合物树脂选自接枝有极性基团的改性聚烯烃树脂或接枝有极性基团的改性聚乙烯-醋酸乙烯酯；加热所述浆料膜和所述聚合物膜以使所述浆料膜转变为改性聚合物树脂固体膜，从而获得所述复合膜。

Description

复合膜及其制备方法、电池模块、电池包和用电装置 技术领域
本申请涉及电池技术领域，尤其涉及一种复合膜及其制备方法、电池模块、电池包和用电装置。
背景技术
近年来，以锂离子电池、钠离子电池为代表的二次电池得到越来越广泛的应用，包括应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。随着锂离子电池和钠离子电池技术的发展，对二者的安全性能等也提出了更高的要求。
为了提高二次电池的安全性，二次电池的表面一般都采用保护膜进行包覆，但是现有的保护膜与二次电池的粘结强度较低，从而导致二次电池的安全性能降低。因此，现有的二次电池的安全性能仍有待提高。
发明内容
本申请是鉴于上述课题而进行的，旨在提供一种复合膜及其制备方法、电池模块、电池包和用电装置，用于解决二次电池的安全性能较低的问题。
为了达到上述目的，本申请的实施例提供一种制备复合膜的方法，包括：
将聚合物膜的表面接枝极性基团以使聚合物膜的表面活化，其中，聚合物膜选自聚烯烃膜或聚乙烯-醋酸乙烯酯膜；
将包含接枝有极性基团的改性聚合物树脂的浆料涂布于聚合物膜的经活化的表面，以形成浆料膜，其中，改性聚合物树脂选自接枝有极性基团的改性聚烯烃树脂或接枝有极性基团的改性聚乙烯-醋酸乙烯酯；
加热浆料膜和聚合物膜以使浆料膜转变为改性聚合物树脂固体膜，从而获得复合膜。
根据本申请实施例的制备复合膜的方法，通过将包含接枝有极性基团的改性聚合物树脂的浆料涂布于经活化的聚合物膜的表面，经加热后获得具有改性聚合物树脂固体膜和聚合物膜的复合膜。并非意在受限于任何理论或解释，将浆料涂布于经活化的聚合物膜的表面，聚合物膜的表面活化后发生表面改性，使聚合物膜与改性聚合物树脂固体膜产生更强的结合力。而且，基于聚合物膜表面接枝的极性基团，以及浆料膜中包含有极性基团，在加热过程中，两个膜层彼此之间相互扩散使得聚合物膜与改性聚合物树脂固体膜之间形成一个渐变界面，不仅降低了改性聚合物树脂固体膜和聚合物膜之间的界面能，还提高了二者之间的复合强度。本申请制备得到的复合膜，聚合物膜具有较高的机械强度和绝缘性能，改性聚合物树脂固体膜具有较高的粘结强度，聚合物膜与改性聚合物树脂固体膜复合形成复合膜，能更好地发挥它们的优势互补和弥补彼此缺点的协同作用，相比于单一保护膜，复合膜整体具有较高的机械强度和绝缘性能，且还具有较好的贴合性和粘结强度。
在本申请的实施例中，对聚合物膜的表面进行活化具体包括：
提供活化液，其中，活化液包含溶解在有机溶剂中的具有极性基团的第一接枝改性单体和自由基引发剂；
在将聚合物膜的表面与活化液接触的情况下，引发自由基引发剂，以使得接枝改性单体接枝到聚合物膜的表面。
在这些可选的实施例中，通过引发自由基引发剂，将第一接枝改性单体接枝到聚合物膜的表面以对聚合物膜的表面进行活化，此活化方法简单且易于操作，而且，制备得到的聚合物膜的表面接枝极性基团分散均匀，使得改性聚合物树脂固体膜与改性聚合物树脂固体膜复合稳定。
在本申请的实施例中在本申请的实施例中，第一接枝改性单体包括不饱和羧酸酐，(甲基)丙烯酸酯，可选地，包括马来酸酐。
在这些可选的实施例中，上述这些接枝改性单体易于溶解在有机溶剂中，且易于被引发剂引发接枝到聚合物膜上。
在本申请的实施例中，自由基引发剂选自过氧化二异丙苯、过氧化苯甲酰、过氧化月桂酸叔丁酯、过氧化苯甲酸叔丁酯和过氧化乙酸叔丁酯中的一种或几种。
在这些可选的实施例中，上述这些自由基引发剂易于溶解在有机溶剂中，而且上述这些自由基引发剂容易受热分解成自由基，易于接枝聚合反应的发生。
在本申请的实施例中，有机溶剂选自N-甲基吡咯烷酮、二甲苯、十氢化萘、松节油或矿物油中的一种或几种。
在这些可选的实施例中，上述这些有机溶剂即能够充分溶解自由基引发剂和接枝改性单体，加热后又易于挥发去除。
在本申请的实施例中，活化液中第一接枝改性单体的质量百分含量为0.5％～1％，可选地为0.7％～0.8％。
在这些可选的实施例中，活化液中第一接枝改性单体具有一定质量，能够充分分散在有机溶剂中，并接枝到聚合物膜的表面，也降低过量的第一接枝改性单体未接枝到聚合物膜的表面而造成浪费。
在本申请的实施例中，活化液中自由基引发剂的质量百分含量为0.1％～0.5％，可选地为0.1％～0.3％。
在这些可选的实施例中，自由基引发剂具有一定质量，与第一接枝改性单体相配合，并通过引发自由基引发剂，以使得第一接枝改性单体充分接枝到聚合物膜的表面。
在本申请的实施例中，引发自由基引发剂，以使得第一接枝改性单体接枝到聚合物膜的表面具体包括：在120～150℃的温度下，对活化液加热1h～3h。
在这些可选的实施例中，通过加热引发自由基引发剂，使得第一接枝改性单体接枝到聚合物膜的表面，上述接枝方式简单且操作可控。
在本申请的实施例中，聚烯烃膜选自聚丙烯膜或聚乙烯膜。
在这些可选的实施例中，上述这些具体可选的聚烯烃膜使得聚合物膜具有更好的绝缘性能和机械性能，且上述具体可选的聚烯烃膜更容易制造。
在本申请的实施例中，浆料的质量浓度为5％～15％，可选地为8％～12％。
在这些可选的实施例中，适宜的浆料的质量浓度使得浆料具有可涂性，且保证后续形成改性聚合物树脂固体膜的厚度。
在本申请的实施例中，改性聚烯烃树脂选自接枝酸酐基团的改性聚丙烯或接枝酸酐基团的改性聚乙烯，可选地，选自接枝马来酸酐基团的改性聚丙烯或接枝马来酸酐基团的改性聚乙烯。
在本申请的实施例中，改性聚乙烯-醋酸乙烯酯为接枝酸酐基团的改性聚乙烯-醋酸乙烯酯，可选地，为接枝马来酸酐基团的改性聚乙烯-醋酸乙烯酯。
在这些可选的实施例中，上述这些具体可选的改性聚合物树脂与形成聚合物膜的树脂同源，能够进一步提高聚合物膜与改性聚合物树脂固体膜之间的复合强度。
在本申请的实施例中，加热浆料膜和聚合物膜的加热温度为50℃～150℃，时间为10h～48h，可选地为80℃～120℃，20h～30h。
在这些可选的实施例中，通过加热可以去除浆料膜中的溶剂以形成改性聚合物树脂固体膜，而且，基于聚合物膜表面接枝的极性基团，以及浆料膜中包含有极性基团，在加热过程中，两个膜层彼此之间相互扩散使得聚合物膜与改性聚合物树脂固体膜之间形成一个渐变界面，提高了聚合物膜与改性聚合物树脂固体膜之间的复合强度。此外，上述加热温度能有效降低对聚合物膜的降解。
在本申请的实施例中，方法还包括制备改性聚合物树脂，所述制备包括：
将聚合物树脂、具有极性基团的第二接枝改性单体和自由基引发剂溶于有机溶剂中，得到混合溶液；
在混合溶液中引发自由基引发剂，以使第二接枝改性单体与聚合物树脂发生接枝反应；
从混合溶液中回收产物，获得改性聚合物树脂。
在这些可选的实施例中，通过溶液法接枝改性，此方法反应温度较低，副反应少，易于操控，且对聚合物树脂的降解程度低。
在本申请的实施例中，混合溶液中聚合物树、第二接枝改性单体和自由基引发剂的质量比为100∶(1～5)∶(0.5～1)。
在这些可选的实施例中，上述聚合物树脂、第二接枝改性单体和自由基引发剂具有适宜的质量比，使得第二接枝改性单体充分接枝到聚合物树脂的表面。
在本申请的实施例中，引发自由基引发剂，以使第二接枝改性单体与聚合物树脂发生接枝反应具体包括：在100～140℃的温度下，对混合溶液加热2h～5h。
在这些可选的实施例中，接枝反应的温度较低，有效降低聚合物树脂的降解程度。
在本申请的实施例中，第二接枝改性单体包括不饱和羧酸酐，(甲基)丙烯酸 酯，可选地，包括马来酸酐。
本申请的实施例还提供可由上述方法制备得到的复合膜。
本申请提供的复合膜既具有较高的机械强度和绝缘性能，又具有较高的粘结强度，聚合物膜与改性聚合物树脂固体膜复合形成复合膜，能更好地发挥它们的优势互补和弥补彼此缺点的协同作用。
在本申请的实施例中，聚合物膜为聚乙烯膜，改性聚合物树脂固体膜的改性聚合物树脂为接枝酸酐基团的改性聚乙烯，可选地，为接枝马来酸酐基团的改性聚乙烯；
在本申请的实施例中，聚合物膜为聚丙烯膜，改性聚合物树脂固体膜的改性聚合物树脂为接枝酸酐基团的改性聚丙烯，可选地，为接枝马来酸酐基团的改性聚丙烯；
在本申请的实施例中，聚合物膜为聚乙烯-醋酸乙烯酯膜，改性聚合物树脂固体膜的改性聚合物树脂为接枝为酸酐基团的改性聚乙烯-醋酸乙烯酯，可选地，为接枝马来酸酐基团的改性聚乙烯-醋酸乙烯酯。
在这些可选的实施例中，上述聚合物膜与其同源的改性聚合物树脂固体膜进行复合，复合强度更高，
在本申请的实施例中，改性聚合物树脂固体膜的厚度为10μm～50μm，可选地为10μm～30μm。
在这些可选的实施例中，改性聚合物树脂固体膜的厚度为10μm～50μm，上述适宜的厚度使得改性聚合物树脂固体膜能够稳定粘接于聚合物膜上，且将复合膜应用于电池模块时，能够保证复合膜的粘结强度。在改性聚合物树脂固体膜的厚度不足10μm的情况下，复合膜成品粘结性较差，在复合膜应用于电池模块时，无法保证复合膜稳定粘结于二次电池上，在改性聚合物树脂固体膜的厚度超过50μm的情况下，改性聚合物树脂固体膜力学强度较低，导致复合膜的力学强度减小。
在本申请的实施例中，聚合物膜的厚度为50μm～130μm，可选地为50μm～90μm。
在这些可选的实施例中，聚合物膜的厚度为50μm～130μm，上述适宜的厚度使得聚合物膜复合具有一定的机械强度和绝缘性能。在聚合物膜的厚度不足50μm的 情况下，复合膜成品的成型性和绝缘性相对不佳，在聚合物膜的厚度超过130μm的情况下，则复合膜的总厚度过厚，柔软性会变差。
本申请的实施例还提供一种复合膜，包括聚合物膜和粘接于聚合物膜表面的改性聚合物树脂固体膜，改性聚合物树脂固体膜的厚度为10μm～50μm，聚合物膜的厚度为50μm～130μm，其中，聚合物膜选自聚烯烃膜或聚乙烯-醋酸乙烯酯膜，改性聚合物树脂固体膜的改性聚合物树脂选自接枝有极性基团的改性聚烯烃树脂或接枝有极性基团的改性聚乙烯-醋酸乙烯酯。
本申请实施例提供的复合膜包括聚合物膜和改性聚合物树脂固体膜，聚合物膜具有较高的机械强度和绝缘性能，改性聚合物树脂固体膜具有较高的粘结强度，聚合物膜与改性聚合物树脂固体膜复合形成复合膜，能更好地发挥它们的优势互补和弥补彼此缺点的协同作用，相比于单一保护膜，复合膜整体具有较高的结构稳定性，且还具有较好的贴合性和粘结强度。
本申请的实施例还提供一种电池模块，包括二次电池和复合膜，复合膜包覆于二次电池的至少部分，且复合膜中的改性聚合物树脂固体膜粘附于二次电池，其中，复合膜是采用上述方法制备得到的复合膜或上述复合膜。
在根据本申请实施例的电池模块中，复合膜通过改性聚合物树脂固体膜的粘结性直接粘附于二次电池上，无需使用热敏胶进行粘结，且复合膜与二次电池粘结强度高，有效降低复合膜与二次电池发生剥离的现象。
本申请的实施例还提供一种制备电池模块的方法，包括：通过热压方式使复合膜包覆于二次电池的表面，获得电池模块，其中，复合膜中的改性聚合物树脂固体膜粘附于二次电池。
根据本申请实施例的制备电池模块的方法，通过热压方式将复合膜包覆于二次电池的表面，其制备方法简单，提高生产效率，而且热压方式能够将复合膜紧密贴合在二次电池的表面，保证复合膜与二次电池紧密包覆。此外，本申请的复合膜在常温状态下，粘结强度较小，方便安装与贴膜，而通过热压处理后，复合膜的粘结强度增加，且高于常规的热敏胶，能够稳定的包覆在二次电池的表面。
在本申请任一实施方式中，热压方式的温度为90℃～180℃，可选地为100℃～150℃。
在这些可选的实施例中，热压方式的温度依据改性聚合物树脂固体膜进行确定，在一定的温度下既能够保证改性聚合物树脂固体膜的粘结强度，又能降低聚合物膜发生降解的缺陷。
在本申请的实施例中，热压方式的压力为0.1MPa～5MPa，可选地为0.5MPa～5MPa。
在这些可选的实施例中，热压方式的压力与温度相配合，使得复合膜紧密粘接在二次电池的表面，且保证复合膜具有一定的厚度，从而使得复合膜具有较高的机械强度。
在本申请的实施例中，热压方式的时间为1s～10s，可选地为3s～5s。
在这些可选的实施例中，适宜的热压时间，保证复合膜具有一定的厚度，从而使得复合膜具有较高的机械强度。
在本申请的实施例中，复合膜复合在二次电池的表面之前还包括：对二次电池的表面先进行喷砂处理，再进行酸化处理。
在这些可选的实施例中，对二次电池的表面进行活化处理，也即喷砂处理和酸化处理，能够去除二次电池的表面的杂质和氧化膜，提高二次电池的表面的清洁度，以及使得二次电池的表面具有一定的粗糙度，使二次电池的表面的机械性能得到改善，从而增加了二次电池的表面与复合膜之间的附着力，延长了复合膜的耐久性。
本申请提供一种电池包，包括上述电池模块或上述方法得到的电池模块。
本申请提供一种用电装置，包括选自上述电池模块、上述方法得到的电池模块或上述电池包。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需要使用的附图作简单地介绍，显而易见地，下面所描述的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据附图获得其他的附图。
图1示出了根据本申请一实施方式的制备复合膜的方法的流程图。
图2示出了制备复合膜的方法中对聚合物膜的表面进行活化的示例性过程的流程图。
图3示出了制备复合膜的方法中形成改性聚合物树脂的示例性过程的流程图。
图4是本申请一实施方式的二次电池的示意图。
图5是图4所示的本申请一实施方式的二次电池的分解图。
图6是本申请一实施方式的电池模块的示意图。
图7是本申请一实施方式的电池包的示意图。
图8是图7所示的本申请一实施方式的电池包的分解图。
图9是本申请一实施方式的二次电池用作电源的用电装置的示意图。
附图标记说明：
1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组件；53盖板。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的负极活性材料及其制备方法、极片、二次电池、电池模块、电池包和用电装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
随着锂离子电池和钠离子电池都取得了极大的发展，对二者的能量密度、循环性能和安全性能等也提出了更高的要求。二次电池的表面一般都采用具有绝缘性能的保护膜进行包覆，保护膜与二次电池之间采用涂胶的方式进行粘结，但是发明人发现，涂胶方式使得保护膜与二次电池连接强度较低，且涂胶不均匀也会导致保护膜粘结强度不一致，使得保护膜的保护性能降低，且容易出现短路的风险。
基于申请人发现的上述问题，本申请提供了复合膜，其包括聚合物膜和改性聚合物树脂固体膜，聚合物膜具有较高的机械强度和绝缘性能，改性聚合物树脂固体膜具有较高的粘结强度，聚合物膜与改性聚合物树脂固体膜复合形成复合膜，能更好地发挥它们的优势互补和弥补彼此缺点的协同作用，相比于单一保护膜，复合膜整体具有较高的结构稳定性，且还具有较好的贴合性和粘结强度。
制备复合膜的方法
图1示出了根据本申请一实施方式的制备复合膜的方法的流程图。
如图1所示，制备复合膜的方法包括：
S1、将聚合物膜的表面接枝极性基团以使聚合物膜的表面活化，
其中，聚合物膜选自聚烯烃膜或聚乙烯-醋酸乙烯酯膜；
S2、将包含接枝有极性基团的改性聚合物树脂的浆料涂布于聚合物膜的经活化的表面，以形成浆料膜，
其中，改性聚合物树脂选自接枝有极性基团的改性聚烯烃树脂或接枝有极性基团的改性聚乙烯-醋酸乙烯酯；
S3、加热浆料膜和聚合物膜以使浆料膜转变为改性聚合物树脂固体膜，从而获得复合膜。
本申请的制备复合膜的方法，通过将包含接枝有极性基团的改性聚合物树脂的浆料涂布于经活化的聚合物膜的表面，经加热后获得具有改性聚合物树脂固体膜和聚合物膜的复合膜。并非意在受限于任何理论或解释，将包含接枝有极性基团的改性聚合物树脂的浆料涂布于经活化的聚合物膜的表面，聚合物膜的表面活化后发生表面改性，使聚合物膜与改性聚合物树脂固体膜产生更强的结合力。而且，基于聚合物膜表面接枝的极性基团，以及浆料膜中包含有极性基团，在加热过程中，两个膜层彼此之间相互扩散使得聚合物膜与改性聚合物树脂固体膜之间形成一个渐变界面，不仅降低了改性聚合物树脂固体膜和聚合物膜之间的界面能，还提高了二者之间的复合强度。此外，本申请制备得到的复合膜，聚合物膜具有较高的机械强度和绝缘性能，改性聚合物树脂固体膜具有较高的粘结强度，聚合物膜与改性聚合物树脂固体膜复合形成复合膜，能更好地发挥它们的优势互补和弥补彼此缺点的协同作用，相比于单一保护膜，复合膜整体具有较高的机械强度和绝缘性能，且还具有较好的贴合性和粘结强度。
根据本申请的实施例，在步骤S1中，通过在选自聚烯烃膜或聚乙烯-醋酸乙烯酯膜的聚合物膜的表面接枝极性基团，可以增加聚合物膜表面的极性，从而实现聚合物膜表面的官能化，提高聚合物膜表面的活性。
示例性的，接枝的极性基团来自不饱和羧酸酐、不饱和羧酸酯。
在本申请的实施例中，聚烯烃膜是以聚烯烃树脂作为成膜基质所形成的膜。在本申请的上下文中，聚烯烃树脂是指由烯烃单体聚合形成的均聚物或共聚物，并包括两种或更多种聚烯烃形成的共混物。
在本申请的实施例中，聚乙烯-醋酸乙烯酯膜是以聚乙烯-醋酸乙烯酯树脂作为成膜基质形成的膜。在本申请的上下文中，聚乙烯-醋酸乙烯酯(EVA)是乙烯和醋酸乙烯酯的共聚物，其中，醋酸乙烯酯(VA)的质量分数小于等于30％、可选地小于等于20％、可选地小于等于15％、可选地小于等于10％。
在本申请一些实施例中，在步骤S2中，包含接枝有极性基团的改性聚合物树脂的浆料具有可涂性，涂布后能够稳定附着在聚合物膜经活化的表面。
可选地，浆料涂覆方式选自凹版、微凹版、丝网印刷、滚筒印刷、电喷涂、转移涂布或挤压涂布中的一种其中。
在本申请一些实施例中，在步骤S3中，对浆料膜和聚合物膜加热，一方面，加热可以去除浆料膜中的溶剂以形成改性聚合物树脂固体膜，另一方面，基于聚合物膜表面活化接枝的极性基团，以及浆料膜中包含有极性基团，在加热过程中，聚合物膜与浆料膜彼此之间相互扩散，使得聚合物膜与改性聚合物树脂固体膜间形成一个渐变界面，提高了二者之间的复合强度。
图2示出了制备复合膜的方法中对聚合物膜的表面进行活化的示例性过程的流程图。
在一些实施例中，如图2所示，步骤S1中对聚合物膜的表面进行活化具体包括：
步骤S11、提供活化液，其中，活化液包含溶解在有机溶剂中的具有极性基团的第一接枝改性单体和自由基引发剂；
步骤S12、在将聚合物膜的表面与活化液接触的情况下，引发自由基引发剂，以使得第一接枝改性单体接枝到聚合物膜的表面。
在本申请的步骤S11中，将有机溶剂、具有极性基团的第一接枝改性单体和自由基引发剂混合，获得活化液。在充分搅拌的条件下，将具有极性基团的第一接枝改性单体和自由基引发剂充分分散在有机溶剂中。
在本申请的步骤S12中，通过自由基引发剂的引发接枝聚合反应，使得第一接枝改性单体接枝到聚合物膜的表面，以对聚合物膜的表面进行改性，从而提高后续与改性聚合物树脂固体膜的结合强度。
可选地，引发自由基引发的方式包括化学法或辐射法。
更可选地，引发自由基引发的方式包括加热法。
在这些可选的实施例中，通过引发自由基引发剂，将第一接枝改性单体接枝到聚合物膜的表面以对聚合物膜的表面进行活化，此活化方法简单且易于操作，而且，制备得到的聚合物膜的表面接枝极性基团分散均匀，使得改性聚合物树脂固体膜与改性聚合物树脂固体膜复合稳定。
在一些实施例中，第一接枝改性单体包括不饱和羧酸酐，(甲基)丙烯酸酯。可选地，接枝改性单体包括马来酸酐。
在这些可选的实施例中，上述这些第一接枝改性单体易于溶解在有机溶剂中，且易于被引发剂引发接枝到聚合物膜上。
在一些实施例中，自由基引发剂选自过氧化二异丙苯、过氧化苯甲酰、过氧化月桂酸叔丁酯、过氧化苯甲酸叔丁酯和过氧化乙酸叔丁酯中的一种或几种。
在这些可选的实施例中，上述这些自由基引发剂易于溶解在有机溶剂中，其上述这些自由基引发剂受热易分解形成自由基，有助于接枝聚合反应的发生。
在一些实施例中，有机溶剂选自N-甲基吡咯烷酮、二甲苯、十氢化萘、松节油或矿物油中的一种或几种。
在这些可选的实施例中，上述这些有机溶剂即能够充分溶解自由基引发剂和第一接枝改性单体，加热后又易于挥发去除。
在一些实施例中，活化液中第一接枝改性单体的质量百分含量为0.5％～1％。
在本申请的一些实施例中，活化液中第一接枝改性单体的质量百分含量为0.5％、0.6％、0.7％、0.8％、0.9％、1％或在由上述的任意两个端点所组成的其它范围内。
可选地，活化液中第一接枝改性单体的质量百分含量为0.7％～0.8％。
在这些可选的实施例中，活化液中第一接枝改性单体具有一定质量，能够充分分散在有机溶剂中，并接枝到聚合物膜的表面，也降低过量的第一接枝改性单体未接枝到聚合物膜的表面而造成浪费。
在一些实施例中，活化液中自由基引发剂的质量百分含量为0.1％～0.5％。
在本申请的一些实施例中，活化液中自由基引发剂的质量百分含量为0.1％、0.2％、0.3％、0.4％、0.5％在由上述的任意两个端点所组成的其它范围内。
可选地，活化液中自由基引发剂的质量百分含量为0.1％～0.3％。
在这些可选的实施例中，自由基引发剂具有一定质量，与第一接枝改性单体相配合，并通过引发自由基引发剂，使得第一接枝改性单体接枝到聚合物膜的表面。
在一些实施例中，引发自由基引发剂，以使得第一接枝改性单体接枝到聚合物膜的表面具体包括：在120℃～150℃的温度下，对活化液加热1h～3h。
在本申请的一些实施例中，引发自由基引发剂，以使得第一接枝改性单体接枝到聚合物膜的表面的温度为120℃、121℃、122℃、123℃、124℃、125℃、126℃、127℃、128℃、129℃、130℃、131℃、132℃、133℃、134℃、135℃、136℃、137℃、138℃、139℃、140℃、141℃、142℃、143℃、144℃、145℃、146℃、147℃、148℃、149℃、150℃或在由上述的任意两个端点所组成的其它范围内。
在本申请的一些实施例中，引发自由基引发剂，以使得第一接枝改性单体接枝到聚合物膜的表面的加热时间为1h、1.1h、1.2h、1.3h、1.4h、1.5h、1.6h、1.7h、1.8h、1.9h、2h、2.1h、2.2h、2.3h、2.4h、2.5h、2.6h、2.7h、2.8h、2.9h、3h或在由上述的任意两个端点所组成的其它范围内。
在这些可选的实施例中，通过加热引发自由基引发剂，使得第一接枝改性单体接枝到聚合物膜的表面，上述接枝方式简单且操作可控。
在一些实施例中，聚烯烃膜选自聚丙烯膜或聚乙烯膜。
在本申请的实施例中，聚丙烯膜是以聚丙烯树脂作为成膜基质所形成的膜。在本申请的上下文中，聚丙烯树脂包括丙烯的均聚物以及丙烯与少量烯烃共单体的共聚物。在本申请的实施例中，聚乙烯膜是以聚乙烯树脂作为成膜基质所形成的膜。在本申请的上下文中，聚乙烯树脂包括乙烯的均聚物以及乙烯与少量烯烃共单体的共聚物。聚乙烯树脂的示例包括，但不限于，高密度聚乙烯(HDPE)、低密度聚乙烯(LDPE)、线性低密度聚乙烯(LLDPE)、聚烯烃弹性体(POE)。
在这些可选的实施例中，上述这些具体可选的聚烯烃膜能够使得聚合物膜具有更好的绝缘性能和机械性能，且上述具体选的聚烯烃膜更容易制备。
在一些实施例中，浆料的质量浓度为5％～15％。
在本申请的一些实施例中，浆料的质量浓度为5％、6％、7％、8％、9％、10％、11％、12％、13％、14％、15％或在由上述的任意两个端点所组成的其它范围内。
可选地，浆料的质量浓度为8％～13％。
在这些可选的实施例中，适宜的浆料的质量浓度使得浆料具有可涂性，且保证后续形成改性聚合物树脂固体膜的厚度。
在一些实施例中，改性聚烯烃树脂选自接枝酸酐基团的改性聚丙烯或接枝酸酐基团的改性聚乙烯。
可选地，改性聚烯烃树脂选自接枝马来酸酐基团的改性聚丙烯或接枝马来酸酐基团的改性聚乙烯。
在一些实施例中，改性聚乙烯-醋酸乙烯酯为接枝酸酐基团的改性聚乙烯-醋酸乙烯酯。
可选地，改性聚乙烯-醋酸乙烯酯为接枝马来酸酐基团的改性聚乙烯-醋酸乙烯酯。
在这些可选的实施例中，上述这些具体可选的改性聚合物树脂与形成聚合物膜的树脂同源，能够进一步提高聚合物膜与改性聚合物树脂固体膜之间的复合强度。
在一些实施例中，加热浆料膜和聚合物膜的加热温度为50℃～150℃，时间为10h～48h。
在本申请的一些实施例中，加热浆料膜和聚合物膜的加热温度为50℃、60℃、70℃、80℃、90℃、100℃、110℃、120℃、130℃、140℃、150℃或在由上述的任意两个端点所组成的其它范围内。
可选地，加热浆料膜和聚合物膜的加热温度为80℃～130℃。
在本申请的一些实施例中，加热浆料膜和聚合物膜的加热时间为10h、11h、12h、13h、14h、15h、16h、17h、18h、19h、20h、21h、22h、23h、24h、25h、26h、27h、28h、29h、30h、31h、32h、33h、34h、35h、36h、37h、38h、39h、40h、41h、42h、43h、44h、45h、46h、47h、48h或在由上述的任意两个端点所组成的其它范围内。
可选地，加热浆料膜和聚合物膜的加热时间为20h～30h。
通过加热可以去除浆料膜中的溶剂以形成改性聚合物树脂固体膜，而且，基于聚合物膜表面接枝的极性基团，以及浆料膜中包含有极性基团，在加热过程中，两个膜层彼此之间相互扩散使得聚合物膜与改性聚合物树脂固体膜之间形成一个渐变界面，提高了聚合物膜与改性聚合物树脂固体膜之间的复合强度。此外，上述加热温度能有效降低对聚合物膜的降解。
图3示出了制备复合膜的方法中形成改性聚合物树脂的示例性过程的流程图。
在一些实施例中，如图3所示，在步骤S2中，还包括制备改性聚合物树脂，制备包括：
S21、将聚合物树脂、具有极性基团的第二接枝改性单体和自由基引发剂溶于有机溶剂中，得到混合溶液；
S22、在混合溶液中引发自由基引发剂，以使第二接枝改性单体与聚合物树脂发生接枝反应；
S23、从混合溶液中回收产物，获得改性聚合物树脂。
在这些可选的实施例中，通过溶液法接枝改性，此方法反应温度较低，副反应少，易于操控，且对聚合物树脂的降解程度低。
在一些实施例中，混合溶液中聚合物树、第二接枝改性单体和自由基引发剂的质量比为100∶(1～5)∶(0.5～1)。
可选地，混合溶液中聚合物树脂、第二接枝改性单体和自由基引发剂的质量比为100∶3∶0.6。
在这些可选的实施例中，上述聚合物树脂、第二接枝改性单体和自由基引发剂具有适宜的质量比，以实现对聚合物树脂表面改性。
在一些实施例中，引发自由基引发剂，以使第二接枝改性单体与聚合物树脂发生接枝反应具体包括：在100℃～140℃的温度下，对混合溶液加热3h～5h。
在这些可选的实施例中，接枝反应的温度较低，有效降低聚合物树脂的降解程度。
在一些实施例中，第二接枝改性单体包括不饱和羧酸酐，(甲基)丙烯酸酯。
可选地，第二接枝改性单体包括马来酸酐。
复合膜
本申请的实施例还提供可由上述方法的任一实施例制备得到的复合膜。
本申请提供的复合膜既具有较高的机械强度、绝缘性能，又具有较高的粘结强度，聚合物膜与改性聚合物树脂固体膜复合形成复合膜，能更好地发挥它们的优势互补和弥补彼此缺点的协同作用。
在一些实施例中，聚合物膜为聚乙烯膜，改性聚合物树脂固体膜的改性聚合物树脂为接枝酸酐基团的改性聚乙烯。
可选地，改性聚合物树脂为接枝马来酸酐基团的改性聚乙烯；
在另一些实施例中，聚合物膜为聚丙烯膜，改性聚合物树脂固体膜的改性聚合物树脂为接枝酸酐基团的改性聚丙烯。
可选地，改性聚合物树脂为接枝马来酸酐基团的改性聚丙烯。
在又一些实施例中，聚合物膜为聚乙烯-醋酸乙烯酯膜，改性聚合物树脂固体膜的改性聚合物树脂为接枝为酸酐基团的改性聚乙烯-醋酸乙烯酯。
可选地，改性聚合物树脂为接枝马来酸酐基团的改性聚乙烯-醋酸乙烯酯。
在这些可选的实施例中，上述聚合物膜与其同源的改性聚合物树脂固体膜进行复合，复合强度更高，
在一些实施例中，改性聚合物树脂固体膜的厚度为10μm～50μm。
在本申请的一些实施例中，改性聚合物树脂固体膜的厚度为10μm、15μm、20μm、25μm、30μm、35μm、40μm、45μm、50μm或在由上述的任意两个端点所组成的其它范围内。
可选地，改性聚合物树脂固体膜的厚度为10μm～30μm。
在这些可选的实施例中，改性聚合物树脂固体膜的厚度为10μm～50μm，上述适宜的厚度使得改性聚合物树脂固体膜能够稳定粘接于聚合物膜上，且将复合膜应用于电池模块时，能够保证复合膜的粘结强度。在改性聚合物树脂固体膜的厚度不足10μm的情况下，复合膜成品粘结性较差，在复合膜应用于电池模块时，无法保证复合膜稳定粘结于二次电池上，在改性聚合物树脂固体膜的厚度超过50μm的情况下，由于改性聚合物树脂固体膜力学强度较低，导致复合膜整体的力学强度减小。
在一些实施例中，聚合物膜的厚度为50μm～130μm。
在本申请的一些实施例中，聚合物膜的厚度为50μm、60μm、70μm、80μm、90μm、100μm、110μm、120μm、130μm或在由上述的任意两个端点所组成的其它范围内。
可选地，聚合物膜的厚度为50μm～90μm。
在这些可选的实施例中，聚合物膜的厚度为50μm～130μm，上述适宜的厚度使得聚合物膜复合具有一定的机械强度和绝缘性能。在聚合物膜的厚度不足50μm的情况下，复合膜成品的成型性和绝缘性相对不佳，在聚合物膜的厚度超过120μm的情况下，则复合膜的总厚度过厚，柔软性会变差。
根据本申请的实施例，还提供了一种复合膜，包括聚合物膜和粘接于聚合物膜表面的改性聚合物树脂固体膜，改性聚合物树脂固体膜的厚度为10μm～50μm，聚合物膜的厚度为50μm～130μm，其中，聚合物膜选自聚烯烃膜或聚乙烯-醋酸乙烯酯膜，改性聚合物树脂固体膜的改性聚合物树脂选自接枝有极性基团的改性聚烯烃树脂或接枝有极性基团的改性聚乙烯-醋酸乙烯酯。。
本申请的聚合物膜由于透明性、机械特性、电特性等优异，被用于作为二次电池的绝缘保护膜，聚合物膜是由聚合物树脂制备形成。
本申请的聚合物膜的厚度为50μm～130μm，上述适宜的厚度使得聚合物膜复合具有一定的机械强度和绝缘性能。在聚合物膜的厚度不足50μm的情况下，复合膜成品的成型性和绝缘性相对不佳，在聚合物膜的厚度超过130μm的情况下，则复合膜的总厚度过厚，柔软性会变差。
本申请的改性聚合物树脂固体膜接枝有极性基团，且其粘结强度高，改性聚合物树脂固体膜能够紧密贴合于聚合物膜的表面，改性聚合物树脂固体膜与聚合物膜为两个相似或相容的表面，二者接触时由于界面能较小，聚合物膜与改性聚合物树脂固体膜之间能够形成稳定的连接。
本申请的改性聚合物树脂固体膜的厚度为10μm～50μm，上述适宜的厚度使得改性聚合物树脂固体膜能够稳定粘接于聚合物膜上，且将复合膜应用于电池模块时，能够保证复合膜的粘结强度。在改性聚合物树脂固体膜的厚度不足10μm的情况下，复合膜成品粘结性较差，在复合膜应用于电池模块时，无法保证复合膜稳定粘结于二次电池上，在改性聚合物树脂固体膜的厚度超过50μm的情况下，改性聚合物树脂固体膜力学强度较低，导致复合膜的力学强度减小。
本申请提供的复合膜包括聚合物膜和改性聚合物树脂固体膜，聚合物膜具有较高的机械强度和绝缘性能，改性聚合物树脂固体膜具有较高的粘结强度，聚合物膜与改性聚合物树脂固体膜复合形成复合膜，能更好地发挥它们的优势互补和弥补彼此缺点的协同作用，相比于单一保护膜，复合膜整体具有较高的结构稳定性，且还具有较好的贴合性和粘结强度。
以下适当参照附图4至图9，对本申请的二次电池、电池模块、电池包和用电装置进行说明。图4是本申请一实施方式的二次电池的示意图。图5是图4所示的本申请一实施方式的二次电池的分解图。图6是本申请一实施方式的电池模块的示意图。图7是本申请一实施方式的电池包的示意图。图8是图7所示的本申请一实施方式的电池包的分解图。图9是本申请一实施方式的二次电池用作电源的用电装置的示意图。
电池模块
电池模块包括二次电池和复合膜，复合膜包覆于二次电池的至少部分，且复合膜中的改性聚合物树脂固体膜粘附于二次电池，其中，复合膜是采用方法制备得到的复合膜或的复合膜。
本申请的电池模块，依据复合膜自身的粘结性，通过改性聚合物树脂固体膜可将复合膜直接粘附于二次电池上，无需使用热敏胶进行粘结，且复合膜与二次电池粘结强度高，有效降低复合膜与二次电池发生剥离的现象。
制备电池模块的方法
制备电池模块的方法，包括：
通过热压方式使复合膜包覆于二次电池的表面，获得电池模块，其中，复合膜中的改性聚合物树脂固体膜粘附于二次电池。
本申请的制备电池模块的方法，通过热压方式将复合膜包覆于二次电池的表面，其制备方法简单，提高生产效率，而且热压方式能够将复合膜紧密贴合在二次电池的表面，保证复合膜与二次电池紧密包覆。此外，本申请的复合膜在常温状态下，粘结强度较小，方便安装与贴膜，而通过热压处理后，复合膜的粘结强度增加，且高于常规的热敏胶，能够稳定的包覆在二次电池的表面。
在一些实施例中，热压方式的温度为90℃～180℃。
在本申请的一些实施例中，热压方式的温度为90℃、100℃、110℃、120℃、130℃、140℃、150℃、160℃、170℃、180℃或在由上述的任意两个端点所组成的其它范围内。
可选地，聚合物膜的厚度为100℃～150℃。
在这些可选的实施例中，热压方式的温度依据改性聚合物树脂固体膜进行确定，在一定的温度下既能够保证改性聚合物树脂固体膜的粘结强度，又能降低聚合物膜降解程度。
在一些实施例中，热压方式的压力为0.1MPa～5MPa。
在本申请的一些实施例中，热压方式的压力为0.1MPa、0.5MPa、1MPa、1.5MPa、2MPa、2.5MPa、3MPa、3.5MPa、4MPa、4.5MPa、5MPa或在由上述的任意两个端点所组成的其它范围内。
可选地，热压方式的压力为0.5MPa～5MPa；
在这些可选的实施例中，热压方式的压力与温度相配合，使得复合膜紧密粘接在二次电池的表面，且保证复合膜具有一定的厚度，从而使得复合膜具有较高的机械强度和剪切强度。
在一些实施例中，热压方式的时间为1s～10s，
在本申请的一些实施例中，热压方式的时间为1s、2s、3s、4s、5s、6s、7s、8s、9s、10s或在由上述的任意两个端点所组成的其它范围内。
可选地，热压方式的时间为3s～5s。
在这些可选的实施例中，适宜的热压时间，保证复合膜具有一定的厚度，从而使得复合膜具有较高的机械强度和剪切强度。
在一些实施例中，复合膜复合在二次电池的表面之前还包括：对二次电池的表面先进行喷砂处理，再进行酸化处理。
可选地，喷砂处理采用粒径2mm砂粒，压缩空气压力0.5MPa。砂粒类型为不锈钢砂、锆砂或金刚砂等。
可选地，酸化处理采用盐酸、硫酸或乙酸等进行酸洗处理。
在这些可选的实施例中，对二次电池的表面进行活化处理，也即喷砂处理和酸化处理，能够去除二次电池的表面的杂质和氧化膜，提高二次电池的表面的清洁 度，以及使得二次电池的表面具有一定的粗糙度，使二次电池的表面的机械性能得到改善，从而增加了二次电池的表面与复合膜之间的附着力，延长了复合膜的耐久性。
通常情况下，二次电池包括正极极片、负极极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极活性材料层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施例中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施例中，正极活性材料可采用本领域公知的用于电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 3)、锂镍氧化物(如LiNiO 3)、锂锰氧化物(如LiMnO 3、LiMn 3O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 3(也可以简称为NCM 333)、LiNi 0.5Co 0.3Mn 0.3O 3(也可以简称为NCM 533)、LiNi 0.5Co 0.35Mn 0.35O 3(也可以简称为NCM 311)、LiNi 0.6Co 0.3Mn 0.3O 3(也可以简称为NCM 633)、LiNi 0.8Co 0.1Mn 0.1O 3(也可以简称为NCM 811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 3)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。
在一些实施例中，正极活性材料层还可以包括导电剂，以改善正极的导电性能。本申请对导电剂的种类不做具体限制，可以根据实际需求进行选择。作为示例，导电剂可以为超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨、石墨烯及碳纳米纤维中的一种或几种。
在一些实施例中，正极活性材料层还可以包括粘结剂，以将正极活性材料和可选的导电剂牢固地粘结在正极集流体上。本申请对粘结剂的种类不做具体限制，可以根据实际需求进行选择。作为示例，粘结剂可以为聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚丙烯酸(PAA)、聚乙烯醇(PVA)、乙烯-醋酸乙烯酯共聚物(EVA)、丁苯橡胶(SBR)、羧甲基纤维素(CMC)、海藻酸钠(SA)、聚甲基丙烯酸(PMA)及羧甲基壳聚糖(CMCS)中的至少一种。
在一些实施例中，正极集流体可以采用导电碳片、金属箔材、涂炭金属箔材、多孔金属板或复合集流体，其中导电碳片的导电碳材质可以为超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨、石墨烯及碳纳米纤维中的一种或几种，金属箔材、涂炭金属箔材和多孔金属板的金属材质各自独立地可以选自铜、铝、镍及不锈钢中的至少一种。复合集流体可以为金属箔材与高分子基膜复合形成的复合集流体。正极集流体例如为铜箔、铝箔、镍箔、不锈钢箔、不锈钢网及涂炭铝箔中的一种或几种，优选采用铝箔。
以按照本领域常规方法制备上述正极极片。通常将正极活性材料及可选的导电剂和粘结剂分散于溶剂(例如N-甲基吡咯烷酮，简称为NMP)中，形成均匀的正极浆料，将正极浆料涂覆在正极集流体上，经烘干、冷压后，得到正极极片。
在本申请的一些实施例中，负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极活性材料层，所述负极活性材料层包括负极活性材料。
所述负极活性材料为通过本申请第一方面的制备方法制得的负极活性材料或本申请的负极活性材料。因此，前面对于根据本申请的负极活性材料的实施例的描述同样适用于二次电池中的负极活性材料，相同的内容不再赘述。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极活性材料层设置在负极集流体相对的两个表面中的任意一者或两者上。
在一些实施例中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材 料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施例中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施例中，负极活性材料层还可选地包括粘结剂。所述粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。
在一些实施例中，负极活性材料层还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施例中，负极活性材料层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
在一些实施例中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极极片。
在本申请的一些实施例中，电解质在正极极片和负极极片之间起到传导离子的作用。本申请对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
在一些实施例中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。
在一些实施例中，电解质盐可选NaPF 6、NaClO 4、NaBF 4、KPF 6、KClO 4、KBF 4、LiPF 6、LiClO 4、LiBF 4、Zn(PF 6) 3、Zn(ClO 4) 3、Zn(BF 4) 3中的一种或几种。
在一些实施例中，电解质盐可选自NaPF 6、NaClO 4、NaBF 4中的一种或几种。
在一些实施例中，溶剂可选自碳酸亚乙酯、碳酸亚丙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯、甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、1,4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜中的至少一种。
在一些实施例中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
在本申请的一些实施例中，对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施例中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施例中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施例中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施例中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图4示出了作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图5，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有 与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件53。电极组件53封装于所述容纳腔内。电解液浸润于电极组件53中。二次电池5所含电极组件53的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图6示出了作为一个示例的电池模块4。参照图6，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
图7和图8示出了作为一个示例的电池包1。参照图7和图8，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体3和下箱体3，上箱体3能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
本申请还提供一种用电装置，所述用电装置包括本申请提供的电池模块或电池包。所述电池模块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为所述用电装置，可以根据其使用需求来选择电池模块或电池包。
图9示出了作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
实施例1
锂离子电池的制造
(1)、正极极片的制备
将正极活性材料、导电剂Super P、粘结剂聚偏二氟乙烯(PVDF)按质量比95∶3∶2在适量的NMP中充分搅拌混合，使其形成均匀的正极浆料。其中正极浆料的粘度为6200mPas且正极浆料静置48h内，不凝胶、不分层、不沉降；正极浆料的固含量为70％；将正极浆料涂覆于正极集流体铝箔的表面上，经干燥、冷压后，得到正极极片。
(2)、负极极片的制备
将负极活性材料人造石墨、导电剂Super P、粘结剂SBR、增稠剂CMC-Na按质量比95∶2∶2∶1在适量的去离子水中充分搅拌混合，使其形成均匀的负极浆料；将负极浆料涂覆于负极集流体铜箔的表面上，经干燥、冷压后，得到负极极片。
(3)、隔离膜
采用PP/PE复合隔离膜。
(4)、电解液的制备
将碳酸亚乙酯(EC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)按体积比1∶1∶1混合，然后将LiPF 6均匀溶解在上述溶液中，得到电解液。该电解液中，LiPF6的浓度为1mol/L，电解液在25℃的离子电导率为10mS/cm。
(5)、二次电池的制备
将正极极片、隔离膜、负极极片按顺序堆叠并卷绕，得到电极组件，将电极组件放入外包装中，加入上述制备的电解液，经封装、静置、化成、老化等工序后，得到二次电池。
制备复合膜的方法
(1)将5g马来酸酐及1g过氧化苯甲酰溶解于100gN-甲基吡咯烷酮中配置成活化液，将活化液刮涂在聚丙烯膜的表面，在120～150℃的温度下，对活化液加热1h～3h引发过氧化苯甲酰，以使得马来酸酐接枝到聚丙烯膜的表面，以使聚丙烯膜的表面活化；
(2)在反应釜中加入100g聚丙烯、3g马来酸酐、0.6g过氧化苯甲酰和100mL二甲苯，将反应体系温度升至120℃，搅拌使固体溶解，随后反应体系在该温度下继续反应4h，反应结束后，将产物倒入1000mL去离子水中，析出固体，过滤回收固体，使用去离子水清洗三遍，烘干得到酸酐改性聚丙烯，将质量浓度为10％的包含酸酐改性聚丙烯的浆料刮涂于聚丙烯膜经活化的表面，刮涂厚度100μm，以形成浆料膜；
(3)在120℃温度下加热浆料膜和聚丙烯膜1h，再在50℃温度下加热24h，以形成酸酐改性聚丙烯膜，获得复合膜。
制备电池模块的方法
对二次电池的铝壳表面采用粒径2mm不锈钢砂，以0.5MPa压缩空气为动力喷砂处理，随后使用5wt％盐酸溶液擦拭铝壳表面的去除污渍，再使用去离子水清洗，于80℃下鼓风烘干备用。
将复合膜使用包膜机包覆于铝壳表面，在0.5MPa压力，150℃温度下热压5s，获得电池模块，其中，酸酐改性聚丙烯膜粘附于铝壳表面，酸酐改性聚丙烯膜的厚度为20μm，聚丙烯膜的厚度为80μm。
实施例2至5以及对比例1至3与实施例1的制备方法相似(聚烯烃膜相等、热压条件相同)，不同的是：聚合物膜的表面未活化，活化液成分，改性聚合物树脂。实施例1至5、对比例1至3的相关参数如表1所示。
实施例6至13以及对比例4至11与实施例1的制备方法相似，不同的是：聚合物膜选自聚乙烯膜、聚丙烯膜或聚乙烯-醋酸乙烯酯膜中的一种，改性聚合物树脂固体膜选自酸酐改性聚乙烯膜、酸酐改性聚丙烯膜或酸酐改性聚乙烯-醋酸乙烯酯膜，聚合物膜的厚度，改性聚合物树脂固体膜的厚度。实施例6至13、对比例4至11的相关参数如表2所示。
实施例14至19以及对比例12至16与实施例1的制备方法相似，不同的是：热压温度、热压时间和热压压力。实施例14至19、对比例12至16的相关参数如表3所示。
按照如下的测试方法测试各实施例和对比例的复合膜。
(1)抗拉强度
裁剪1×10cm矩形复合膜样品，测量厚度t，装入测试夹具之间，上下夹具间距5cm。采用UTM6000万能试验机测试拉伸性能，测试速度5mm/min。测试完成后，通过仪器记录下的最大力F，按如下公式计算抗拉强度(σ)。
σ＝F/(0.01×t)
(2)剪切强度
将复合膜裁剪成2.5×10cm的矩形长条，贴附于铝板表面，参照国标GB/T 7124-2008方法测试。
(3)绝缘耐压测试
将复合膜裁剪成5×5cm的矩形长条，贴附于铝板表面，采用SMR990绝缘耐压仪测试进行2000kV，30s耐压测试，漏电流≤1.5mA则通过。
(4)附着力
按照国标GB/T 9286-1998方法测试，将保护膜粘附于150×100mm铝板表面，置于水平刚性平面上。使用百格刀垂直于样品切割，所有切割均应划透至基材表面。随后在与原切割线90°相交方向作同样数量的切割，形成网格线。随后，使用软毛刷扫几次，将透明胶带贴于网格上方，压平后撕离胶带。对照附着力分级评定表对于粘结保护膜附着力。
(5)老化测试
将保护膜裁剪成2.5×10cm的矩形长条，贴附于铝板表面，至于85℃/85％条件下1000h，测试保护膜老化后的剪切强度及附着力。
表1实施例1～5对比例1～3参数结果
Figure PCTCN2022119799-appb-000001
Figure PCTCN2022119799-appb-000002
表2实施例1、6～13和对比例4～11参数结果
Figure PCTCN2022119799-appb-000003
Figure PCTCN2022119799-appb-000004
表3实施例1、14～19对比例12～16参数结果
Figure PCTCN2022119799-appb-000005
Figure PCTCN2022119799-appb-000006
根据上述结果可知，实施例1至19，均取得了良好的效果，
本申请将浆料涂布于经活化的聚合物膜的表面，聚合物膜的表面活化后发生表面改性，使聚合物膜与改性聚烯烃聚合物树脂固体膜产生更强的结合力，而且，聚合物膜的表面活化接枝的极性基团与浆料膜中包含接枝有极性基团在加热的过程中，彼此之间相互扩散使得聚合物膜与改性聚合物树脂固体膜间形成一个渐变界面，不仅降低了改性聚合物树脂固体膜和聚合物膜之间的界面能，还提高了二者之间的复合强度。获得的复合膜既具有较高的机械强度、绝缘性能和剪切强度，又具有较高的 粘结强度，聚合物膜与改性聚合物树脂固体膜复合形成复合膜，能更好地发挥它们的优势互补和弥补彼此缺点的协同作用。
实施例1～5的制备复合膜的方法，主要体现在复合膜的抗拉强度。对比例1、2和3，将聚合物膜的表面与活化液接触，不合适上述工艺条件，聚合物膜与改性聚合物树脂固体膜复合稳定较差。
进一步参照实施例1～12和13，聚合物膜与其同源的改性聚合物树脂固体膜进行复合，复合强度更高。
进一步参照实施例8～11，改性聚合物树脂固体膜的厚度为10μm～50μm，上述适宜的厚度使得改性聚合物树脂固体膜能够稳定粘接于聚合物膜上，且将复合膜应用于电池模块时，能够保证复合膜的粘结强度。聚合物膜的厚度为50μm～130μm，上述适宜的厚度使得聚合物膜复合具有一定的机械强度和绝缘性能。
进一步参照实施例14～19，通过热压方式将复合膜包覆于二次电池的表面，其制备方法简单，提高生产效率，而且热压方式能够将复合膜紧密贴合在二次电池的表面，保证复合膜与二次电池紧密包覆。此外，本申请的复合膜在常温状态下，粘结强度较小，方便安装与贴膜，而通过热压处理后，复合膜的粘结强度增加，且高于常规的热敏胶，能够稳定的包覆在二次电池的表面。
虽然已经参考优选实施例对本申请进行了描述，但在不脱离本申请的范围的情况下，可以对其进行各种改进并且可以用等效物替换其中的部件。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (17)

  1. 一种制备复合膜的方法，包括：
    将聚合物膜的表面接枝极性基团以使所述聚合物膜的表面活化，其中，所述聚合物膜选自聚烯烃膜或聚乙烯-醋酸乙烯酯膜；
    将包含接枝有极性基团的改性聚合物树脂的浆料涂布于所述聚合物膜的经活化的表面，以形成浆料膜，其中，所述改性聚合物树脂选自接枝有极性基团的改性聚烯烃树脂或接枝有极性基团的改性聚乙烯-醋酸乙烯酯；
    加热所述浆料膜和所述聚合物膜以使所述浆料膜转变为改性聚合物树脂固体膜，从而获得所述复合膜。
  2. 根据权利要求1所述的制备复合膜的方法，其中，所述对所述聚合物膜的表面进行活化具体包括：
    提供活化液，其中，所述活化液包含溶解在有机溶剂中的具有极性基团的第一接枝改性单体和自由基引发剂；
    在将所述聚合物膜的表面与所述活化液接触的情况下，引发所述自由基引发剂，以使得所述第一接枝改性单体接枝到所述聚合物膜的表面。
  3. 根据权利要求2所述的制备复合膜的方法，其中，
    所述活化液满足下述(1)～(5)中的一个或几个：
    (1)所述第一接枝改性单体包括不饱和羧酸酐，(甲基)丙烯酸酯，可选地，包括马来酸酐；
    (2)所述自由基引发剂选自过氧化二异丙苯、过氧化苯甲酰、过氧化月桂酸叔丁酯、过氧化苯甲酸叔丁酯和过氧化乙酸叔丁酯中的一种或几种；
    (3)所述有机溶剂选自N-甲基吡咯烷酮、二甲苯、十氢化萘、松节油或矿物油中的一种或几种；
    (4)所述活化液中所述第一接枝改性单体的质量百分含量为0.5％～1％，可选地为0.7％～0.8％；
    (5)所述活化液中所述自由基引发剂的质量百分含量为0.1％～0.5％，可选地为0.1％～0.3％；和/或
    所述引发所述自由基引发剂，以使得所述第一接枝改性单体接枝到所述聚合物膜 的表面具体包括：在130～150℃的温度下，对所述活化液加热1h～3h。
  4. 根据权利要求1所述的制备复合膜的方法，其中，
    所述复合膜满足下述(6)～(10)中的一个或几个：
    (6)所述聚烯烃膜选自聚丙烯膜或聚乙烯膜；
    (7)所述浆料的质量浓度为5％～15％，可选地为8％～13％；
    (8)所述改性聚烯烃树脂选自接枝酸酐基团的改性聚丙烯或接枝酸酐基团的改性聚乙烯，可选地，选自接枝马来酸酐基团的改性聚丙烯或接枝马来酸酐基团的改性聚乙烯；
    (9)所述改性聚乙烯-醋酸乙烯酯为接枝酸酐基团的改性聚乙烯-醋酸乙烯酯，可选地，为接枝马来酸酐基团的改性聚乙烯-醋酸乙烯酯；
    (10)加热所述浆料膜和所述聚合物膜的加热温度为50℃～150℃，时间为10h～48h，可选地为80℃～130℃，20h～30h。
  5. 根据权利要求2至4任一项所述的制备复合膜的方法，还包括制备所述改性聚合物树脂，所述制备包括：
    将聚合物树脂、具有极性基团的第二接枝改性单体和自由基引发剂溶于有机溶剂中，得到混合溶液；
    在所述混合溶液中引发所述自由基引发剂，以使所述第二接枝改性单体与所述聚合物树脂发生接枝反应；
    从所述混合溶液中回收产物，获得所述改性聚合物树脂。
  6. 根据权利要求5所述的制备复合膜的方法，其中，
    所述混合溶液中所述聚合物树脂、所述第二接枝改性单体和所述自由基引发剂的质量比为100∶(1～5)∶(0.5～1)；和/或
    所述引发所述自由基引发剂，以使所述第二接枝改性单体与所述聚合物树脂发生接枝反应具体包括：在100～140℃的温度下，对所述混合溶液加热3h～5h；和/或
    所述第二接枝改性单体包括不饱和羧酸酐，(甲基)丙烯酸酯，可选地，包括马来酸酐。
  7. 一种可由权利要求2至6任一项所述的方法制备得到的复合膜。
  8. 根据权利要求7所述的复合膜，其中，
    所述复合膜满足下述(11)～(13)中的一个或几个：
    (11)所述聚合物膜为聚乙烯膜，所述改性聚合物树脂固体膜的改性聚合物树脂为接枝酸酐基团的改性聚乙烯，可选地，为接枝马来酸酐基团的改性聚乙烯；
    (12)所述聚合物膜为聚丙烯膜，所述改性聚合物树脂固体膜的改性聚合物树脂为接枝酸酐基团的改性聚丙烯，可选地，为接枝马来酸酐基团的改性聚丙烯；
    (13)所述聚合物膜为聚乙烯-醋酸乙烯酯膜，所述改性聚合物树脂固体膜的改性聚合物树脂为接枝为酸酐基团的改性聚乙烯-醋酸乙烯酯，可选地，为接枝马来酸酐基团的改性聚乙烯-醋酸乙烯酯。
  9. 根据权利要求7或8所述的复合膜，其中，
    所述改性聚合物树脂固体膜的厚度为10μm～50μm，可选地为10μm～30μm。
  10. 根据权利要求7至9任一项所述的复合膜，其中，
    所述聚合物膜的厚度为50μm～130μm，可选地为50μm～90μm。
  11. 一种复合膜，包括聚合物膜和粘接于所述聚合物膜表面的改性聚合物树脂固体膜，所述改性聚合物树脂固体膜的厚度为10μm～50μm，所述聚合物膜的厚度为50μm～130μm，其中，所述聚合物膜选自聚烯烃膜或聚乙烯-醋酸乙烯酯膜，所述改性聚合物树脂固体膜的改性聚合物树脂选自接枝有极性基团的改性聚烯烃树脂或接枝有极性基团的改性聚乙烯-醋酸乙烯酯。
  12. 一种电池模块，包括：
    二次电池；以及
    复合膜，所述复合膜包覆于二次电池的至少部分，且所述复合膜中的改性聚合物树脂固体膜粘附于所述二次电池，
    其中，所述复合膜是采用权利要求1～6中任一项所述方法制备得到的复合膜或权利要求7至10中任一项所述的复合膜。
  13. 一种制备电池模块的方法，包括：
    通过热压方式使复合膜包覆于二次电池的表面，获得所述电池模块，其中，所述复合膜中的改性聚合物树脂固体膜粘附于所述二次电池。
  14. 根据权利要求13所述的制备电池模块的方法，其中，
    所述热压方式满足下述(14)～(16)中的一个或几个：
    (14)所述热压方式的温度为90℃～180℃，可选地为100℃～150℃；
    (15)所述热压方式的压力为0.1MPa～5MPa，可选地为0.5MPa～5MPa；
    (16)所述热压方式的时间为1s～10s，可选地为3s～5s。
  15. 根据权利要求13所述的制备电池模块的方法，其中，
    所述复合膜复合在所述二次电池的表面之前还包括：对所述二次电池的表面先进行喷砂处理，再进行酸化处理。
  16. 一种电池包，包括权利要求13所述的电池模块或权利要求13至15任一项所述方法得到的电池模块。
  17. 一种用电装置，包括选自权利要求13所述的电池模块、权利要求13至15任一项所述方法得到的电池模块或权利要求16所述的电池包。
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