Isolating membrane and preparation method thereof, battery and electric device

Abstract

The invention provides an isolating membrane. The isolating membrane comprises a base membrane and a coating arranged on at least one side surface of the base membrane, the coating comprises a color developing agent, and the color developing agent can develop under the irradiation of excitation light. The color developing agent is added into the isolating membrane coating, so that the isolating membrane can be developed, and whether defects such as coating missing, coating non-uniformity and pinholes exist in the coating or not can be easily detected and found.

Description

Isolation film and preparation method thereof, battery and electrical device Technical Field

[0001] The present application belongs to the field of new energy material technology, and specifically relates to an isolation membrane and a preparation method thereof, a battery, and an electrical device. Background Art

[0002] Batteries are widely used in various consumer electronic products and electric vehicles due to their outstanding features such as light weight, no pollution, and no memory effect.

[0003] The continuous development of the new energy industry is placing higher demands on batteries. For example, some batteries may experience separator anomalies, which can cause a short circuit between the positive and negative electrodes, posing a safety hazard. However, existing separator anomalies are difficult to detect and diagnose. Therefore, how to conveniently detect separator anomalies is a pressing issue.

[0004] Summary of the Invention

[0005] In view of the technical problems existing in the background technology, the present application provides an isolation membrane and a preparation method thereof, a battery and an electrical device, aiming to enhance the characteristics of the isolation membrane to achieve more intuitive abnormality detection.

[0006] In order to achieve the above-mentioned purpose, the first aspect of the present application provides an isolation film, which includes: a base film, and a coating arranged on at least one side surface of the base film; the coating includes a color developer, and the color developer can develop color under the irradiation of excitation light.

[0007] Compared to the prior art, the present application offers at least the following advantages: by adding a coloring agent to the barrier film coating, the barrier film can be colored, making it easier to detect defects such as coating leaks, uneven coating, and pinholes. The coloring agent selected in this case can be a luminescent agent that emits colored light, offering a wide range of options, high brightness, and long luminescence duration without affecting the barrier film's basic performance. Specifically, when inspecting the barrier film, the barrier film is exposed to light of a specific wavelength, causing it to develop color. The displayed color can then be used to determine whether any defects or abnormalities are present. Upon removal from the specific light, the barrier film returns to its original state.

[0008] In any embodiment of the present application, the color developer includes a fluorescent agent that emits colored fluorescence under ultraviolet light. The use of a fluorescent agent facilitates detection conditions, reducing detection costs. Furthermore, the detection light has no significant impact on the basic properties of the isolation membrane, and the displayed color is brighter and easier to distinguish, thereby improving detection accuracy and efficiency.

[0009] In any embodiment of the present application, the fluorescent agent includes one or more of rare earth-doped tungstates, rare earth-doped phosphates, rare earth-doped silicates, rare earth-doped titanates, and rare earth-doped aluminates. The selected materials have stable chemical properties, no significant impact on battery performance, are sensitive, have simple luminescence triggering conditions, and emit high brightness and long duration. They are environmentally friendly, safe, and low-cost, making them suitable for mass production.

[0010] In any embodiment of the present application, rare earth doped tungstate includes CaWO4:Eu 3+ 、CaWO4:Dy 3+ 、CaWO4:Sm 3+ 、CaWO4:Tb 3+ One or more of .

[0011] In any embodiment of the present application, the rare earth doped phosphate includes NaCaPO4:Eu 2+ 、NaCaPO4:Tb 3+ 、Ba2Mg(PO4)2:Ce 3+ 、Ba2Mg(PO4)2:Tb 3+ One or more of .

[0012] In any embodiment of the present application, the rare earth doped silicate comprises Ca8Mg(SiO4)4Cl2:Eu 2+ .

[0013] In any embodiment of the present application, rare earth doped titanate includes NaGdTiO4:Sm 3+ 、NaLaTiO4:Eu 3+ 、NaLaTiO4:Dy 3+ .

[0014] In any embodiment of the present application, the rare earth doped aluminate comprises SrAl2O4:Eu 2+ 、SrAl2O4:Dy 3+ One or more of .

[0015] In any embodiment of the present application, the coating further includes a filler, wherein the filler includes one or more of inorganic particles having a dielectric constant of 5 or higher, inorganic particles capable of transporting active ions, and inorganic particles capable of electrochemical oxidation and reduction. The addition of the filler can further improve the thermal stability of the separator, thereby enhancing the safety performance of the battery.

[0016] In any embodiment of the present application, the coating further includes a binder, and the binder includes one or more of polyacrylate, polyacrylonitrile, styrene-butadiene rubber, epoxy resin, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, polybutyl acrylate-ethylhexyl acrylate copolymer, polymethyl methacrylate-ethylhexyl acrylate copolymer, polyvinyl chloride, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trichloroethylene copolymer, polyvinyl alcohol, styrene, polycyanoacrylate, polymethyl methacrylate, polyvinyl pyrrolidone, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyimide, gelatin, polyethylene glycol, polyethylene glycol dimethyl ether, and ethylene glycol dimethyl ether. The addition of the binder can bond the components in the coating, and can also enhance the bonding force between the coating and the base film, reduce abnormalities such as powder loss of the coating, extend the service life of the separator, and thereby improve the cycle performance and safety of the battery.

[0017] In any embodiment of the present application, the coating further comprises one or more of a dispersant, a wetting agent, and a thickener. The addition of a dispersant, a wetting agent, and a thickener can improve the uniformity of the coating slurry, better disperse the solid phase components in the coating slurry in the liquid phase components, and thereby control the solid content and fluidity of the coating slurry; thereby achieving a more uniform coating during coating and reducing defects such as coating leaks and pinholes.

[0018] In any embodiment of the present application, the dispersant includes one or more of polyvinyl pyrrolidone and polyethylene glycol. The selection of these dispersants can promote the uniform dispersion of the developer and filler, so that the resulting coating is more uniform.

[0019] In any embodiment of the present application, the thickener includes one or more of methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose. The selection of these thickeners can increase the solid content of the coating slurry and reasonably control the fluidity of the slurry to facilitate coating.

[0020] In any embodiment of the present application, the wetting agent includes one or more of silicone, glycerol, N-methylpyrrolidone, sodium dodecylbenzenesulfonate, and perfluorosulfonate. These wetting agents are selected to more easily act on the filler and the developer, reducing their surface tension or interfacial tension, making them more easily wetted by the liquid phase, thereby facilitating dispersion.

[0021] In any embodiment of the present application, the developer content is 1% to 50% by weight, preferably 5% to 30% by weight, based on the mass of the coating. By regulating the developer within this range, the brightness of the emitted light can be increased, resulting in more pronounced color, thereby improving detection efficiency and accuracy. This does not affect the basic properties of the isolation membrane, such as air permeability.

[0022] In any embodiment of the present application, the Dv50 particle size of the developer is 0.01 μm to 3 μm, preferably 0.1 μm to 1 μm. By regulating the particle size of the developer within the given range, the developer can meet the color development requirements while not affecting the basic performance of the isolation membrane. For example, the air permeability of the isolation membrane will not be increased due to the addition of more additives.

[0023] In any embodiment of the present application, the base film is a single layer, and the coating is located on one side or both sides of the base film. By providing the coating, the isolation film can have better heat resistance and mechanical strength.

[0024] In any embodiment of the present application, the base film has a two-layer structure, with the coating located between the two base films, or on one or both sides of at least one base film. By providing two base films, the separator can have excellent heat resistance, as well as good tensile strength and puncture resistance, reducing the risk of lithium dendrites penetrating the separator and improving battery safety.

[0025] In any embodiment of the present application, the base film has a multi-layer structure, and the coating is located between two base films, or on one or both sides of at least one base film. By combining the multi-layer base film and the coating, multiple functions can be superimposed and enhanced, thereby improving the overall performance of the isolation membrane.

[0026] In any embodiment of the present application, the air permeability of the separator is 100-400 s / 100 cc. Compared with conventional separators, the additive has no significant effect on the air permeability of the separator.

[0027] In any embodiment of the present application, the coating layer has a thickness of 0.1 μm to 10 μm, preferably 0.5 μm to 5 μm; the base film has a thickness of 2-12 μm, preferably 3-9 μm. By regulating the base film and coating layer thicknesses within the given ranges, the total thickness of the separator can be reduced while still meeting color development requirements, thereby reducing the separator's space usage within the battery and increasing battery capacity.

[0028] A second aspect of the present application provides a method for preparing an isolation film, which includes providing a base film;

[0029] A coating slurry is provided, comprising a color developer capable of developing color under irradiation with excitation light; the coating slurry is applied to at least one surface of a base film to produce any of the aforementioned isolation films. The preparation method provided herein enables detection of defects such as coating leaks, uneven coating, and pinholes, allowing for timely process improvements and increased product yield.

[0030] In one embodiment, the content of the developer in the coating slurry is 0.5%-30%, preferably 4%-15%.

[0031] In one embodiment, the color developer includes a fluorescent agent, which can be prepared using a high-temperature solid-phase method or a sol-gel method. The high-temperature solid-phase method is preferred. Specifically, one or more powders are poured into a ball mill and milled for several hours to mix them uniformly. The powders are then sintered in a high-temperature furnace at 700°C-1200°C. After the sintered product cools, it is ground again to obtain the fluorescent agent with the target particle size. This method is environmentally friendly, safe, and low-cost, making it suitable for mass production.

[0032] A third aspect of the present application provides a battery comprising a positive electrode, a negative electrode, and a separator as described above; the separator is used to separate adjacent positive electrodes and negative electrodes.

[0033] Since the battery of the present application includes the isolation membrane provided by the present application, when an abnormality occurs, the isolation membrane can be effectively tested to check whether there is any abnormality in the isolation membrane, so as to find out whether the defect is caused by the isolation membrane.

[0034] A fourth aspect of the present application provides an electrical device comprising the above-mentioned battery.

[0035] Since the device of the present application includes the battery provided by the present application, it has at least the same advantages as the battery.

[0036] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] To more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings used in this application. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without inventive effort.

[0038] FIG1 is a schematic structural diagram of a vehicle according to some embodiments of the present application;

[0039] FIG2 is a schematic diagram of the exploded structure of a battery according to some embodiments of the present application;

[0040] FIG3 is a schematic diagram of the exploded structure of a battery cell according to some embodiments of the present application;

[0041] FIG4 is a schematic diagram of the cross-sectional structure of an isolation membrane according to some embodiments of the present application;

[0042] FIG5 is a schematic diagram of the cross-sectional structure of an isolation membrane according to some embodiments of the present application;

[0043] FIG6 is a schematic diagram of the cross-sectional structure of an isolation membrane according to some embodiments of the present application. DETAILED DESCRIPTION

[0044] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0046] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0047] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0048] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0049] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0050] Unless otherwise specified, the terms used in this application have the commonly understood meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the various parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the examples of this application).

[0051] In recent years, with the development of new energy technologies, batteries have been used in a wide range of consumer electronics and electric vehicles, becoming a part of almost everyone's daily lives. This has led to increasingly stringent requirements for battery safety. Battery safety incidents can occur due to a variety of factors, one of which may be due to a faulty separator. This is because the separator is used to insulate the positive and negative electrodes. A faulty separator can easily cause a short circuit between the positive and negative electrodes, creating a safety hazard.

[0052] Generally, an isolation film comprises a base film, or a base film and a coating disposed on at least one surface of the base film. The base film is typically made of a colorless or white polymer material, and the coating is similarly colorless or white. This makes it difficult for the naked eye or a machine to visually identify defects such as uneven base film thickness, uneven coating, missing coatings, and pinholes in the coating. These defects can reduce the performance of the isolation film and pose a significant safety hazard.

[0053] To address this technical problem, the present application provides an isolation film comprising a base film and a coating disposed on at least one surface of the base film. The coating includes a color developer capable of developing color when irradiated with excitation light. By adding the color developer to the isolation film coating, the isolation film develops color, making it easier to detect defects in the coating, such as coating leaks, uneven coating, and pinholes.

[0054] The isolation membrane disclosed in the embodiments of the present application can be applied to batteries, which can be used in electrical devices that use the battery as a power source or various energy storage systems that use the battery as an energy storage element. The electrical devices can include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, battery-powered vehicles, electric vehicles, ships, spacecraft, and the like. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like, and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, and the like.

[0055] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0056] Please refer to Figure 1, which is a schematic structural diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0057] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0058] Please refer to Figure 2, which is a schematic diagram of the exploded structure of a battery 100 provided in some embodiments of the present application. The battery 100 includes a housing 10 and battery cells 20, with the battery cells 20 housed within the housing 10. The housing 10 provides a storage space for the battery cells 20 and can have various structures. In some embodiments, the housing 10 can include a first portion 11 and a second portion 12, which overlap each other and together define a storage space for the battery cells 20. The second portion 12 can be a hollow structure with one end open. The first portion 11 can be a plate-like structure, with the first portion 11 overlapping the open side of the second portion 12, so that the first portion 11 and the second portion 12 together define a storage space. Alternatively, the first portion 11 and the second portion 12 can each be a hollow structure with one end open, with the open side of the first portion 11 overlapping the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder or a rectangular parallelepiped.

[0059] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0060] Each battery cell 20 may be a secondary battery or a primary battery, and may also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0061] Please refer to Figure 3, which is a schematic diagram of the exploded structure of a battery cell 20 provided in some embodiments of the present application. A battery cell 20 is the smallest unit that makes up a battery. As shown in Figure 3, a battery cell 20 includes an end cap 21, a housing 22, an electrode assembly 23, and other functional components.

[0062] The end cap 21 is a component that covers the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the end cap 21 can be adapted to the shape of the housing 22 to fit the housing 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as an aluminum alloy). This prevents the end cap 21 from deforming when subjected to compression or collision, thereby providing the battery cell 20 with greater structural strength and improved safety. The end cap 21 can be provided with functional components such as electrode terminals 21a. The electrode terminals 21a can be used to electrically connect to the electrode assembly 23 for inputting or outputting electrical energy from the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism for relieving internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The end cap 21 can also be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any particular limitations on this. In some embodiments, an insulating member may be provided inside the end cap 21 to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. For example, the insulating member may be made of plastic, rubber, or the like.

[0063] The housing 22 is a component that cooperates with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can be used to accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and end cap 21 can be separate components. An opening can be provided in the housing 22, and the end cap 21 is placed over the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and housing 22 can be integrated. Specifically, the end cap 21 and housing 22 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 22 needs to be enclosed, the end cap 21 is placed over the housing 22. The housing 22 can have a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, or a hexagonal prism. Specifically, the shape of the housing 22 can be determined based on the specific shape and size of the electrode assembly 23. The housing 22 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any particular limitations on this.

[0064] The electrode assembly 23 is a component in the battery cell 100 where electrochemical reactions occur. One or more electrode assemblies 23 may be contained in the housing 22. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active materials constitute the main body of the electrode assembly, and the parts of the positive and negative electrode sheets without active materials each constitute a tab 23a. The positive tab and the negative tab may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive active material and the negative active material react with the electrolyte, and the tab 23a connects the electrode terminals to form a current loop.

[0065] According to some embodiments of the present application, an isolation film is provided, which includes a base film and a coating arranged on at least one side surface of the base film; the coating includes a color developer, and the color developer can develop color under the irradiation of excitation light.

[0066] The color developer may be a fluorescent agent that absorbs incident light to produce fluorescence, giving the substance a shimmering effect similar to fluorite. Different colors can be presented by absorbing light of different light rays.

[0067] In this embodiment, by adding a color developer to the barrier film coating, the barrier film develops color, making it easy to detect defects such as coating skips, uneven coating, and pinholes. This process does not significantly impact the barrier film's basic performance. Specifically, when inspecting the barrier film, the barrier film is exposed to light of a specific wavelength, causing it to emit colored light, thus developing color. This color is then used to detect defects. Once the specific light is removed, the barrier film returns to its original state, maintaining the ability to observe the barrier film's surface cleanliness.

[0068] In any embodiment of the present application, the color developer includes a fluorescent agent, which can emit colored light under the irradiation of ultraviolet light.

[0069] Compared to other luminescent agents, fluorescent agents have brighter colors and higher contrast. When detecting defects in a coating by color, they are easier to observe and distinguish, and the detection results are more accurate. For some fluorescent agents, the luminescence phenomenon disappears immediately once the incident light stops. The emitted light with this property is called fluorescence. In addition, some substances can continue to emit light for a long time after the incident light is removed. This phenomenon is called afterglow. That is, an isolation film with added fluorescent agents can emit light under excitation light and may also emit light after it is removed. Furthermore, by selecting a fluorescent agent, the detection conditions are easier to achieve, thereby reducing the impact of the ultraviolet light used for detection on the basic performance of the isolation film. The displayed color is brighter and easier to distinguish, which can improve detection accuracy and efficiency.

[0070] In any embodiment of the present application, the phosphor includes one or more of rare earth-doped tungstates, rare earth-doped phosphates, rare earth-doped silicates, rare earth-doped titanates, rare earth-doped aluminates, and metal-doped sulfides. The selected materials have stable chemical properties, no significant impact on battery performance, are sensitive, have simple luminescence triggering conditions, and exhibit high brightness and long-lasting luminescence. They are environmentally friendly, safe, and low-cost, making them suitable for mass production.

[0071] One or more fluorescent agents can be selectively added to an isolation film to produce different colors of light. Two fluorescent agents emitting the same color can be selected to enhance the luminous effect, or fluorescent agents emitting different colors can be selected to mix and produce more colors of light.

[0072] In any embodiment of the present application, rare earth doped tungstate includes CaWO4:Eu 3+ 、CaWO4:Dy 3+ 、CaWO4:Sm 3+ 、CaWO4:Tb 3+ One or more of .

[0073] In any embodiment of the present application, rare earth doped phosphate NaCaPO4:Eu 2+ 、NaCaPO4:Tb 3+ 、Ba2Mg(PO4)2:Ce 3+ 、Ba2Mg(PO4)2:Tb 3+ One or more of .

[0074] In any embodiment of the present application, the rare earth doped silicate comprises Ca8Mg(SiO4)4Cl2:Eu 2+ .

[0075] In any embodiment of the present application, rare earth doped titanate includes NaGdTiO4:Sm 3+ 、NaLaTiO4:Eu 3+ 、NaLaTiO4:Dy 3+ .

[0076] In any embodiment of the present application, the rare earth doped aluminate comprises SrAl2O4:Eu 2+ 、SrAl2O4:Dy 3+ One or more of .

[0077] In any embodiment of the present application, the coating further comprises a filler, and the filler comprises one or more of inorganic particles having a dielectric constant of 5 or higher, inorganic particles capable of transporting active ions, and inorganic particles capable of electrochemical oxidation and reduction.

[0078] Among them, the inorganic particles having a dielectric constant of 5 or higher may include boehmite (γ-AlOOH), aluminum oxide (Al2O3), barium sulfate (BaSO4), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2), silicon oxide SiO x (0<x≤2), tin dioxide (SnO2), titanium oxide (TiO2), calcium oxide (CaO), zinc oxide (ZnO), zirconium oxide (ZrO2), yttrium oxide (Y2O3), nickel oxide (NiO), hafnium dioxide (HfO2), cerium oxide (CeO2), zirconium titanate (ZrTiO3), barium titanate (BaTiO3), magnesium fluoride (MgF2), Pb(Zr,Ti)O3 (abbreviated as PZT), Pb 1-m La m Zr 1-n Ti n O3 (abbreviated as PLZT, 0<m<1, 0<n<1) and Pb(Mg3Nb 2 / 3 ) at least one of O3-PbTiO3 (abbreviated as PMN-PT).

[0079] In some embodiments, the inorganic particles capable of transporting active ions may include lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0<x<2, 0<y<3), lithium aluminum titanium phosphate (Li x Al y Ti z (PO4)3, 0<x<2, 0<y<1, 0<z<3), (LiAlTiP) x O y Glass-like (0<x<4, 0<y<13), lithium lanthanum titanate (Li x Lay TiO3, 0<x<2, 0<y<3), lithium germanium thiophosphate (Li x Ge y P z S w , 0<x<4, 0<y<1, 0<z<1, 0<w<5), lithium nitride (Li x N y , 0<x<4, 0<y<2), SiS2 type glass (Li x Si y S z , 0<x<3, 0<y<2, 0<z<4) and P2S5 type glass (Li x P y S z , 0<x<3, 0<y<3, 0<z<7).

[0080] In some embodiments, the inorganic particles capable of electrochemical oxidation and reduction may include at least one selected from lithium-containing transition metal oxides, lithium-containing phosphates with olivine structures, carbon-based materials, silicon-based materials, tin-based materials, and lithium titanium compounds.

[0081] By adding fillers, the thermal stability of the separator can be further improved, thereby enhancing battery safety. For example, heat-resistant fillers can be added to enhance the heat resistance of the separator, thereby reducing the possibility of the separator being broken down by heat.

[0082] In any embodiment of the present application, the coating further includes a binder, and the binder includes one or more of polyacrylate, polyacrylonitrile, styrene-butadiene rubber, epoxy resin, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, polybutyl acrylate-ethylhexyl acrylate copolymer, polymethyl methacrylate-ethylhexyl acrylate copolymer, polyvinyl chloride, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trichloroethylene copolymer, polyvinyl alcohol, styrene, polycyanoacrylate, polymethyl methacrylate, polyvinyl pyrrolidone, polyvinyl acetate, ethylene and vinyl acetate copolymer, polyimide, gelatin, polyethylene glycol, polyethylene glycol dimethyl ether, and ethylene glycol dimethyl ether. The addition of the binder can enhance the bonding between the components in the coating, and can also enhance the bonding between the coating and the base film, reduce abnormalities such as powder loss of the coating, extend the service life of the isolation membrane, and thereby improve the cycle performance and safety of the battery.

[0083] In any embodiment of the present application, the coating further comprises one or more of a dispersant, a wetting agent, and a thickener. The addition of a dispersant, a wetting agent, and a thickener can improve the uniformity of the coating slurry, better disperse the solid phase components in the coating slurry in the liquid phase components, and thereby control the solid content and fluidity of the coating slurry; thereby achieving a more uniform coating during coating and reducing defects such as coating leaks and pinholes.

[0084] In any embodiment of the present application, the dispersant includes one or more of polyvinyl pyrrolidone and polyethylene glycol.

[0085] In any embodiment of the present application, the thickener includes one or more of methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose.

[0086] In any embodiment of the present application, the wetting agent includes one or more of silicone, glycerin, N-methylpyrrolidone, sodium dodecylbenzenesulfonate, and perfluorosulfonate.

[0087] In any embodiment of the present application, the mass percentage of the color developer is 1%-50%, preferably 5%-30%, based on the mass of the coating. Specifically, it can be 0.5%, 0.8%, 1.1%, 1.3%, 1.5%, 1.8%, 2.3%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, etc. By regulating the luminescent agent within the given range, the brightness of the emitted light can be increased, thereby improving the detection efficiency and accuracy. At the same time, it will not affect the basic performance of the isolation membrane. For example, the air permeability of the isolation membrane will not be increased due to the addition of more additives.

[0088] In any embodiment of the present application, the Dv50 particle size of the color developer is 0.01μm-3μm, preferably 0.1μm-1μm. Specifically, it can be 0.05μm, 0.1μm, 0.5μm, 1μm, 2μm, etc. Dv50 is the particle size corresponding to when the cumulative volume percentage of the material reaches 50%. By regulating the particle size of the luminescent agent within the given range, the luminescent agent can meet the color development requirements while not affecting the basic performance of the isolation membrane. For example, the air permeability of the isolation membrane will not be increased due to the addition of more additives. Volume distribution particle size Dv50 test: Referring to the standard GB / T 19077.1-2016, Dv50 can be obtained by measuring using a laser particle size analyzer (such as Malvern Master Size 3000), where Dv50 is physically defined as the particle size corresponding to when the cumulative volume distribution percentage of the material reaches 50%. The Dv50 of the negative electrode material obtained in each embodiment and comparative example is 7μm.

[0089] In any embodiment of the present application, the base film is structured as a single layer, with the coating layer located on one or both sides of the base film. By providing the coating layer, the isolation film can have excellent properties, such as good heat resistance and mechanical strength. As shown in FIG4 , FIG4 is a schematic cross-sectional structure diagram of an isolation film according to some embodiments of the present application. Isolation film 30 includes a base film 31 and a coating layer 32 . Coating layer 32 includes a first coating layer 321 and a second coating layer 322 . The first coating layer 321 and the second coating layer 322 are located on either side of the base film 31 .

[0090] In any embodiment of the present application, the structure of the base film is two layers, and the coating is located between the two base films, or on one side or both sides of at least one base film. By providing two layers of base film, the isolation membrane can have good performance, such as good heat resistance, and at the same time good tensile strength and puncture resistance. In addition, the generation of lithium dendrites can be suppressed, while reducing the risk of the diaphragm being penetrated by lithium dendrites, thereby improving the safety of the battery. As shown in Figure 5, Figure 5 is a schematic diagram of the cross-sectional structure of the isolation membrane of some embodiments of the present application. The isolation membrane 30 includes a base film 31 and a coating 32. The base film 31 includes a first base film 311 and a second base film 312. The coating 32 is located between the first base film 311 and the second base film 312 as an intermediate layer.

[0091] In any embodiment of the present application, the structure of the base film is multi-layered, and the coating is located between two base films, or on one side or both sides of at least one base film. By combining the multi-layer base film and the coating, it is possible to achieve the superposition and enhancement of multiple functions, thereby improving the overall performance of the isolation film. As shown in Figure 6, Figure 6 is a schematic diagram of the cross-sectional structure of the isolation film in some embodiments of the present application. The isolation film 30 includes a base film 31 and a coating 32. The base film 31 includes a first base film 311 and a second base film 312. The coating 32 includes a first coating 321 and a second coating 322. The first base film 311, the first coating 321, the second base film 312, and the second coating 322 are stacked in sequence.

[0092] In any embodiment of the present application, the air permeability of the separator is 100-400 s / 100 cc. Compared with conventional separators, the additive has no significant effect on the air permeability of the separator.

[0093] In any embodiment of the present application, the thickness of the coating is 0.1 μm-10 μm, preferably 0.5 μm-5 μm, and specifically 0.8 μm, 2 μm, 5 μm, 7 μm, 9 μm, etc. By regulating the coating within the given range, the total thickness of the separator can be reduced while meeting the color rendering requirements, thereby reducing the space occupied by the separator in the battery and increasing the battery capacity.

[0094] A second aspect of the present application provides a method for preparing an isolation film, comprising providing a coating slurry including a color developer capable of developing color under irradiation with excitation light; and applying the coating slurry to at least one surface of a base film to obtain any of the aforementioned isolation films. The preparation method provided herein enables detection of defects such as coating leaks, uneven coating, and pinholes, enabling timely process improvements and improving product yield.

[0095] Specifically, a color developer and filler are dispersed in deionized water in a certain weight ratio, and then a binder, dispersant, thickener, and wetting agent are added and stirred to prepare a coating slurry. The color developer, filler, binder, dispersant, thickener, and wetting agent used can be any one or more of the above-mentioned embodiments.

[0096] The content of the developer in the coating slurry is 0.5%-30%, preferably 4%-15%.

[0097] Fluorescent agents can be prepared using either a high-temperature solid-phase method or a sol-gel method, with the high-temperature solid-phase method being preferred. This involves pouring one or more powders into a ball mill and milling them for several hours to achieve a uniform mixture. The mixture is then sintered in a furnace at 700-1200°C. After the sintered product cools, it is ground again to obtain the fluorescent agent of the target particle size. This method offers advantages such as environmental friendliness, safety, and low cost, making it suitable for mass production.

[0098] The coating slurry is applied to the surface of the base film by a micro-concave roller to obtain a release film.

[0099] The coated diaphragm is conveyed to a specific light irradiation area, where different fluorescent colors are generated according to the addition of different fluorescent agents. Process abnormalities caused by fluorescent color differences such as uneven coating, coating omissions and other defects are identified and recorded.

[0100] A third aspect of the present application provides a battery comprising a positive electrode, a negative electrode, and a separator as described above; the separator is used to separate adjacent positive electrodes and negative electrodes.

[0101] Since the battery of the present application includes the isolation membrane provided by the present application, when an abnormality occurs, the isolation membrane can be effectively tested to check whether there is any abnormality in the isolation membrane, so as to find out whether the defect is caused by the isolation membrane.

[0102] A fourth aspect of the present application provides an electrical device comprising the above-mentioned battery.

[0103] Since the device of the present application includes the battery provided by the present application, it has at least the same advantages as the battery. The power-consuming device can be any of the aforementioned devices or systems using batteries.

[0104] The solutions of the present application are described below with reference to specific embodiments. Those skilled in the art will understand that the isolation membrane and the preparation method thereof described in the present application are merely examples, and any other suitable solutions are within the scope of the present application.

[0105] Specifically, the color developer and filler are dispersed in deionized water in a certain weight ratio, and then a binder, a dispersant, a thickener and a wetting agent are added and stirred to prepare a coating slurry.

[0106] The filler is inorganic ceramic particles, the binder is polyacrylate, the dispersant is polyvinyl pyrrolidone, the thickener is carboxymethyl cellulose, and the wetting agent is siloxane. The color developer can be a fluorescent agent. For specific substances, see Table 1. The weight fraction of the fluorescent agent in the coating slurry is controlled. See Table 1 for details.

[0107] The coating slurry is applied to the surface of the base film by a micro-concave roller to obtain a separator. The air permeability of the separator is then tested using an air permeability tester. The specific operating steps are as follows: cut the separator to a suitable size and fix it on the instrument. The test instrument applies a certain pressure. 100mL of air passes through an area of ​​642mm. 2 The time required for gas to pass through the membrane is the permeability value of the membrane.

[0108] The coated diaphragm is brought to the UV irradiation area, where the UV light excites the fluorescent agent. The CCD then identifies the color difference between the abnormal point and the normal area on the coated film surface and locks the abnormal area, thereby achieving abnormality detection.

[0109] The obtained separator was made into a battery, cycled at room temperature for 10 cls, the battery was disassembled, the separator was taken out, and the fluorescence effect of the separator was tested. For specific results, please refer to Table 1.

[0110] Table 1: Performance parameters of various examples and comparative examples

[0111] From the data in Table 1, it can be seen that the coating of Example 5 is unevenly luminous, indicating uneven coating and unqualified separator; while the coatings of Examples 1-4 are uniformly luminous, indicating good coating effect and qualified separator; after being used in the battery for a period of time, it is found that the coating of Example 3 is no longer uniformly luminous, indicating that the separator is damaged during use, which may cause battery safety problems and needs to be replaced in time.

[0112] Therefore, the addition of a fluorescent agent creates a pronounced fluorescence effect under specific lighting conditions, enabling the detection of defects such as coating leaks, uneven coating, and pinholes. Furthermore, the addition of a fluorescent agent does not significantly increase the air permeability of the separator, essentially unaffecting its fundamental performance. Furthermore, the separator maintains a pronounced fluorescence effect after battery cycling, providing valuable guidance for subsequent separator analysis during abnormal cell disassembly.

[0113] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present application, and such modifications or substitutions should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A separation film, wherein: include: A base film, and a coating disposed on at least one surface of the base film; The coating layer includes a color developer, which can develop color under the irradiation of excitation light.

2. The isolation film according to claim 1, characterized in that: The color developer includes a fluorescent agent, and the fluorescent agent can emit colored fluorescence under the irradiation of ultraviolet rays.

3. The isolation film according to claim 2, characterized in that: The fluorescent agent includes one or more of rare earth doped tungstate, rare earth doped phosphate, rare earth doped silicate, rare earth doped titanate, rare earth doped aluminate, and metal doped sulfide.

4. The isolation membrane according to claim 3, characterized in that: The rare earth doped tungstate comprises CaWO4:Eu 3+ 、CaWO4:Dy 3+ 、CaWO4:Sm 3+ 、CaWO4:Tb 3+ One or more of; and / or The rare earth doped phosphate includes NaCaPO4:Eu 2+ 、NaCaPO4:Tb 3+ 、Ba2Mg(PO4)2:Ce 3+ 、Ba2Mg(PO4)2:Tb 3+ One or more of; and / or The rare earth doped silicate comprises Ca8Mg(SiO4)4Cl2:Eu 2+ ; and / or The rare earth doped titanate comprises NaGdTiO4:Sm 3+ 、NaLaTiO4:Eu 3+ 、NaLaTiO4:Dy 3+ ; and / or The rare earth doped aluminate comprises SrAl2O4:Eu 2+ 、SrAl2O4:Dy 3+ One or more of; and / or The metal-doped sulfide includes one or more of ZnS:Ag, ZnS:Cu, CdS:Ag, and CdS:Cu.

5. The isolation film according to any one of claims 1 to 4, characterized in that: Based on the mass of the coating, the mass percentage of the developer is 1%-50%, preferably 5%-30%.

6. The isolation film according to any one of claims 1 to 5, characterized in that: The volume distribution particle size Dv50 of the developer is 0.01 μm-3 μm, preferably 0.1 μm-1 μm.

7. The isolation membrane according to any one of claims 1 to 6, characterized in that: The coating layer further includes a filler, and the filler includes one or more of inorganic particles having a dielectric constant of 5 or higher, inorganic particles having the ability to transport active ions, and inorganic particles capable of electrochemical oxidation and reduction.

8. The isolation membrane according to any one of claims 1 to 7, characterized in that: The coating also includes a binder, which includes polyacrylate, polyacrylonitrile, One or more of styrene-butadiene rubber, epoxy resin, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, polybutyl acrylate-ethylhexyl acrylate copolymer, polymethyl methacrylate-ethylhexyl acrylate copolymer, polyvinyl chloride, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trichloroethylene copolymer, polyvinyl alcohol, styrene, polycyanoacrylate, polymethyl methacrylate, polyvinyl pyrrolidone, polyvinyl acetate, ethylene and vinyl acetate copolymer, polyimide, gelatin, polyethylene glycol, polyethylene glycol dimethyl ether, ethylene glycol dimethyl ether.

9. The isolation film according to any one of claims 1 to 8, characterized in that: The base film includes a first base film and a second base film, and the coating layer is located between the first base film and the second base film.

10. The isolation film according to any one of claims 1 to 9, characterized in that: The air permeability of the isolation film is 100-400s / 100cc.

11. The isolation film according to any one of claims 1 to 10, characterized in that: The thickness of the coating is 0.1 μm-10 μm, preferably 0.5 μm-5 μm; The thickness of the base film is 2-12 μm, preferably 3 μm-9 μm.

12. A method for preparing an isolation film, characterized in that: include: providing a basement membrane; Providing a coating slurry, wherein the coating slurry includes a developer, and the developer can develop color under the irradiation of excitation light; The coating slurry is coated on at least one side of the surface of the base film to obtain the isolation film according to any one of claims 1 to 11.

13. The method for preparing an isolation film according to claim 12, characterized in that: The content of the developer in the coating slurry is 0.5%-30%, preferably 4%-15%.

14. A battery, characterized in that: It comprises a positive electrode, a negative electrode and a separator as described in any one of claims 1 to 11; the separator is used to separate the adjacent positive electrode and the negative electrode.

15. An electrical device, characterized in that: Comprising the battery of claim 14.

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