Battery monomer and preparation method thereof, diaphragm, battery device and power utilization device

Abstract

The invention discloses a battery monomer and a preparation method thereof, a diaphragm, a battery device and a power utilization device, the battery monomer comprises a shell and a battery cell assembly and an electrolyte arranged in the shell, the battery cell assembly is located in the electrolyte, the battery cell assembly comprises a positive pole piece, a negative pole piece and the diaphragm, and the diaphragm is located between the positive pole piece and the negative pole piece; the diaphragm comprises a base membrane and a first coating arranged on at least one side of the base membrane, the first coating comprises a polymer material, and the melting point or glass transition temperature of the polymer material is 90-140 DEG C; the polymer material has a volume median particle size of 10 nm to 10 [mu] m. Through the arrangement, the thermal stability of the battery is improved, and the safety of the battery is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to battery cells and their preparation methods, separators, battery devices, and electrical devices. Background Technology

[0002] As battery technology continues to develop, the requirements for the overall performance of batteries are becoming increasingly stringent, with safety being the primary prerequisite for stable battery development.

[0003] When a battery is subjected to mechanical, electrical, or thermal shocks, a localized and dramatic temperature rise occurs inside the battery, leading to heat accumulation and spread. This can cause thermal runaway, potentially resulting in a fire or even a complete battery failure. Therefore, to maintain battery safety, it is necessary to improve its thermal stability. Summary of the Invention

[0004] This application provides a battery cell and its preparation method, a separator, a battery device, and an electrical device to improve the thermal stability of the battery.

[0005] To address the aforementioned technical problems, the first aspect of this application provides a battery cell, comprising: a casing, a cell assembly disposed within the casing, and an electrolyte. The cell assembly is located in the electrolyte and includes a positive electrode, a negative electrode, and a separator, with the separator located between the positive and negative electrode. The separator includes a base film and a first coating disposed on at least one side of the base film. The first coating includes a polymer material with a melting point or glass transition temperature of 90°C-140°C and a median particle size of 10 nm-10 μm.

[0006] By setting the melting point or glass transition temperature of the polymer material to 90℃-140℃, the polymer material melts at a temperature lower than the thermal closure temperature of the base film. The thermal closure temperature refers to the temperature at which the base film melts or shrinks, closing the channels that allow ions to pass through. The first coating melts before the base film when the separator temperature rises, closing the ion channels and reducing the separator's thermal closure temperature. This helps mitigate thermal runaway and improves battery safety. Simultaneously, under the heating or pressurizing conditions of hot pressing, baking, and formation processes during the assembly of the separator with the positive and negative electrodes, the separator has not yet reached its thermal closure temperature and remains in an effective state, maintaining the battery's electrical performance. This approach has good practical application prospects.

[0007] By setting the median particle size Dv50 of the polymer material to 10nm-10μm, the pore structure of the first coating is suitable, which can allow ions to pass through smoothly during battery use, and can also quickly close the channels on the base film and the first coating that allow ions to pass through when the internal temperature of the battery reaches 90℃-140℃, thereby reducing battery thermal runaway, improving battery thermal stability, and helping to improve battery safety.

[0008] In one embodiment, the melting point or glass transition temperature of the polymer material is 100°C-130°C.

[0009] The above settings help to further reduce the thermal closure temperature of the separator, improve the thermal pore-closing function of the separator, thereby helping to reduce the thermal runaway of the battery and improve the battery safety. At the same time, under the heating or pressurization conditions of hot pressing, baking, and formation processes during the assembly of the separator with the positive and negative electrode plates, the separator does not reach the thermal closure temperature, reducing the impact of the separator on ion transport and maintaining better electrical performance of the battery.

[0010] In one embodiment, the bulk median particle size of the polymer material is 300 nm to 2 μm.

[0011] By setting the median particle size Dv50 of the polymer material to 300nm-2μm, the pore structure of the first coating is suitable, which can maintain smooth ion transport during battery use, and can also quickly close the channels on the base film and the first coating that allow ions to pass through when the internal temperature of the battery reaches the closure temperature, thereby reducing battery thermal runaway, improving battery thermal stability, and improving battery safety.

[0012] In one embodiment, the density of the polymer material is 0.1 g / cm³. 3 -10g / cm 3 .

[0013] By setting the density of the polymer material to 0.1 g / cm³ 3 -10g / cm 3 During the process of forming the first coating using an aqueous slurry, the polymer material has good dispersion in the slurry, which helps to maintain the uniformity of the polymer material covering the base film. When the internal temperature of the battery reaches the pore-closing temperature of the separator, the polymer material can quickly close the ion channels at various locations. The good dispersion of the polymer material in the slurry helps to maintain the consistency of the first coating during the mass production of separators, thus maintaining the consistency of the product separators.

[0014] In one embodiment, the polymer has a density of 0.5 g / cm³. 3 -2g / cm 3 .

[0015] By setting the density of the polymer material to 0.5 g / cm³ 3 -2g / cm 3 During the process of forming the first coating using an aqueous slurry, the polymer material has good dispersion in the slurry, and the polymer material covers the base film more evenly. When the internal temperature of the battery reaches the pore-closing temperature of the separator, the polymer material can quickly close the ion channels at various locations. The good dispersion of the polymer material in the slurry is beneficial to maintaining the consistency of the first coating and the consistency of the product separator during the mass production of separators.

[0016] In one embodiment, the polymer material includes at least one of polyacrylic acid, polymethyl methacrylate and its derivatives, polyvinylidene fluoride, acrylonitrile-butadiene-styrene copolymer, carboxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, styrene-acrylic rubber, polyacrylonitrile, polyvinyl acetal, polylactic acid, polylactic acid-glycolic acid copolymer, acrylate-vinyl acetate-styrene copolymer, and acrylate-vinyl acetate copolymer.

[0017] By selecting the aforementioned polymer material, the polymer material melts at a temperature lower than the closure temperature of the base membrane. At this temperature, the polymer material closes the channels through which ions pass, reducing the thermal closure temperature of the separator and improving its thermal pore-closing function. This, in turn, helps to reduce the thermal runaway of the battery and improve its safety.

[0018] In one embodiment, the first coating further includes a first inorganic material; the weight ratio between the polymer material and the first inorganic material is 1-50 parts of polymer material and 1-50 parts of the first inorganic material.

[0019] By including a first inorganic material in the first coating and setting the weight ratio between the polymer material and the first inorganic material as described above, the first inorganic material increases the porosity of the first coating, reducing the probability of partial ion channel closure caused by deformation of the polymer material under conditions such as heating or pressurization during the battery cell assembly manufacturing process. This helps maintain the smooth passage of ions through the separator during the production process and normal use. By adding the first inorganic material, the mechanical strength of the first coating can be enhanced by utilizing its properties, and the first coating can maintain its structural integrity even at the thermal closure temperature.

[0020] In one embodiment, the mass ratio of the polymer material to the first inorganic material in the first coating is 1:6 to 6:1.

[0021] By setting the mass ratio between the polymer material and the first inorganic material as described above, the amount of the first inorganic material added is more suitable, which helps the first coating maintain sufficient porosity and improves the stability of the first coating. It can maintain structural integrity at the thermal closure temperature and help to quickly close the ion channels when the thermal closure temperature is reached, thus hindering further ion migration and improving the safety of the battery.

[0022] In one embodiment, the median particle size of the first inorganic material is 10 nm to 10 μm.

[0023] By setting the median particle size Dv50 of the first inorganic material as described above, the first inorganic material is more uniformly dispersed in the polymer material, forming a dense mesh structure, maintaining the smoothness of ion transport, and when the thermal closure temperature is reached, the first coating can quickly close the ion channel, which is beneficial to improving the safety of the battery.

[0024] In one embodiment, the median particle size of the first inorganic material is 300 nm to 2 μm.

[0025] By setting the median particle size Dv50 of the first inorganic material as described above, the first inorganic material is more evenly dispersed in the polymer material, forming a finer network structure. The thermal response of the material with the above-mentioned particle size is more rapid. When the thermal closure temperature is reached, the first coating can close the ion channels more quickly, which is beneficial to improving the safety of the battery.

[0026] In one embodiment, the first inorganic material includes at least one of aluminum oxide, boehmite, barium sulfate, silicon dioxide, magnesium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, zirconium oxide, and titanium dioxide.

[0027] By selecting the aforementioned material as the first inorganic material, which has heat resistance and is not easily decomposed at the thermal closure temperature, it can serve as a thermal trigger point to promote the rapid thermal closure of the first coating, thereby effectively reducing thermal runaway inside the battery and improving the battery's safety performance.

[0028] In one embodiment, the thickness of the first coating is 0.5 μm to 4 μm.

[0029] By setting the thickness of the first coating as described above, sufficient polymer material can be provided to effectively thermally close the ion channels, and the heat transfer is relatively fast, enabling rapid response to changes in battery temperature to achieve thermal closure.

[0030] In one embodiment, the thickness of the first coating is 1.5 μm to 3 μm.

[0031] By setting the thickness of the first coating as described above, sufficient polymer material can be provided to effectively thermally close the ion channels. At the same time, heat transfer is faster, and the thermal closure is achieved more quickly in response to changes in battery temperature.

[0032] In one embodiment, the diaphragm further includes a second coating comprising a second inorganic material; the second coating is disposed on the side of the first coating away from the base membrane, or the second coating is disposed on the side of the base membrane where the first coating is not disposed.

[0033] By further adding a second coating, which includes a second inorganic material with heat resistance, the separator can achieve thermal closure while maintaining its heat resistance, which is beneficial to improving the thermal stability of the separator. This improves the membrane rupture temperature to a certain extent, reduces membrane shrinkage, and reduces the risk of short circuit between the positive and negative electrodes, thus improving the safety of the battery.

[0034] When the second coating is applied to the side of the first coating away from the base film, when the internal temperature of the battery rises to the thermal closure temperature, the polymer material of the first coating becomes molten and transforms into a strong adhesive layer between the base film and the second coating, enhancing the stability of the adhesive interface between the base film and the second coating.

[0035] In one embodiment, the median particle size of the second inorganic material is 10 nm to 10 μm.

[0036] By setting the volume median particle size Dv50 of the second inorganic material as described above, the second inorganic material can form a relatively dense and stable second coating, which enhances the mechanical strength and thermal stability of the diaphragm. The second inorganic material with the above particle size can provide a larger specific surface area, which is conducive to heat transfer and dispersion, improves the thermal response speed, and helps to trigger the thermal closure performance of the first coating.

[0037] In one embodiment, the median particle size of the second inorganic material is 300 nm to 2 μm.

[0038] By setting the median particle size Dv50 of the second inorganic material as described above, the second inorganic material can form a more stable second coating, further enhancing the mechanical strength and thermal stability of the diaphragm; the second inorganic material with the above particle size can provide a larger specific surface area, which is conducive to heat transfer and dispersion, improves the thermal response speed, and helps to trigger the thermal closure performance of the first coating.

[0039] In one embodiment, the second inorganic material includes at least one of aluminum oxide, boehmite, barium sulfate, silicon dioxide, magnesium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, zirconium oxide, and titanium dioxide.

[0040] By selecting the aforementioned material as the second inorganic material, which has good heat resistance, the thermal stability of the separator can be improved. This can improve the membrane rupture temperature to a certain extent, reduce membrane shrinkage, and prevent membrane rupture at the thermal closure temperature. This reduces the risk of short circuit between the positive and negative electrodes and improves battery safety.

[0041] In one embodiment, the thickness of the second coating is 0.5 μm to 4 μm.

[0042] By setting the thickness of the second coating as described above, the membrane maintains high mechanical strength and thermal stability. At the same time, it can transfer heat relatively quickly, so that the first coating can quickly close the ion channels when the battery temperature reaches the thermal closure temperature, reducing the risk of thermal runaway.

[0043] In one embodiment, the thickness of the second coating is 1.5 μm to 3 μm.

[0044] By setting the thickness of the second coating as described above, the membrane maintains high mechanical strength and thermal stability. At the same time, it can transfer heat more quickly, so that the first coating can quickly close the ion channels when the battery temperature reaches the thermal closure temperature, reducing the risk of thermal runaway.

[0045] In one embodiment, the thickness of the base film is 1 μm-30 μm.

[0046] By setting the thickness of the base membrane as described above, the internal resistance of the separator is appropriate, maintaining smooth ion transport; it also has good mechanical strength and puncture resistance, which can reduce the risk of short circuits caused by external forces and improve battery safety.

[0047] In one embodiment, the porosity of the base membrane is 10%-80%.

[0048] By setting the porosity of the base membrane as described above, the separator can better absorb and retain the electrolyte, ensuring that there is enough electrolyte inside the battery to participate in the electrochemical reaction, thereby improving battery performance.

[0049] In one embodiment, the base film includes at least one of polyethylene film, polypropylene film, polyethylene-polypropylene composite film, polyimide film, and polyester film.

[0050] By designing the base membrane using the aforementioned materials, which possess good mechanical strength, the separator provides excellent mechanical support for the battery.

[0051] To address the aforementioned technical problems, a second aspect of this application provides a method for preparing a battery cell, comprising: sequentially stacking a negative electrode, a separator, and a positive electrode to form a cell assembly; placing the cell assembly in a housing; and injecting an electrolyte into the housing and sealing it to form a battery cell; wherein the method for preparing the separator comprises: providing a base film; coating at least one side of the base film with a first slurry to form a first coating; the first slurry comprising a polymer material having a melting point or glass transition temperature of 90°C-140°C; and a median particle size of 10 nm-10 μm.

[0052] The preparation method of battery cells has at least the same advantages as that of battery cells.

[0053] In one embodiment, the first slurry further includes a first inorganic material, a first binder, a first dispersant, a first wetting agent, and a first solvent. The weight ratio of the polymer material, the first inorganic material, the first binder, the first dispersant, the first wetting agent, and the first solvent is as follows: 1 part to 50 parts of polymer material, 1 part to 50 parts of first inorganic material, 1 part to 10 parts of first binder, 0.1 part to 2 parts of first dispersant, 0.01 part to 1 part of first wetting agent, and 1 part to 80 parts of first solvent.

[0054] By setting the components and their proportions as described above, the uniform dispersion of the first inorganic material and polymer material in the first slurry is maintained. The first inorganic material increases the porosity of the first coating, reducing the probability of partial ion channel closure caused by deformation of the polymer material under heating or pressurization conditions during the battery cell assembly manufacturing process. This helps maintain the smooth passage of ions through the separator during production and normal use. Furthermore, by adding the first inorganic material, the mechanical strength of the first coating can be enhanced, and the first coating can maintain its structural integrity even at thermal closure temperatures.

[0055] In one embodiment, the method for preparing the diaphragm further includes: coating a second slurry on the side of the first coating away from the base film or on the side of the base film where the first coating is not provided, to form a second coating; wherein the second slurry includes a second inorganic material, a second binder, a second dispersant, a second wetting agent, and a second solvent; the weight ratio of the second inorganic material, the second binder, the second dispersant, the second wetting agent, and the second solvent is: 1 part to 80 parts of the second inorganic material, 1 part to 10 parts of the second binder, 0.1 part to 2 parts of the second dispersant, 0.01 part to 1 part of the second wetting agent, and 1 part to 80 parts of the second solvent.

[0056] The second coating is formed by coating, which is simple to operate and helps maintain the consistency of the resulting separator product. By setting the components and proportions of the second slurry as described above, the dispersion uniformity of the second inorganic material in the second slurry is maintained. The second inorganic material has heat resistance properties, enabling the separator to achieve thermal closure while maintaining its heat resistance, which helps improve the thermal stability of the separator. To a certain extent, this improves the membrane rupture temperature, reduces membrane shrinkage, and minimizes the risk of membrane rupture at the thermal closure temperature, thus reducing the risk of short circuits between the positive and negative electrodes and improving battery safety.

[0057] In one embodiment, the polymer material includes at least one of polyacrylic acid, polymethyl methacrylate and its derivatives, polyvinylidene fluoride, acrylonitrile-butadiene-styrene copolymer, carboxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, styrene-acrylic rubber, polyacrylonitrile, polyvinyl acetal, polylactic acid, polylactic-glycolic acid copolymer, and acrylate-vinyl acetate-styrene copolymer; and / or, the first inorganic material and the second inorganic material each independently include at least one of alumina, boehmite, barium sulfate, silicon dioxide, magnesium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, zirconium oxide, and titanium dioxide. ; and / or, the first adhesive and the second adhesive each independently include at least one of polyacrylic acid, polyacrylate, styrene-butadiene rubber, styrene-acrylic emulsion, polyurethane, and polyacrylonitrile; and / or, the first dispersant and the second dispersant each independently include at least one of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, sodium polyacrylate, and polyacrylamide; and / or, the first wetting agent and the second wetting agent each independently include at least one of alkyl alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, polyoxyethylene ether, alkylbenzene sulfonate, and alkyl sulfate; and / or, the first solvent and the second solvent each independently include water.

[0058] By selecting the aforementioned polymer materials, the polymer material melts at a temperature lower than the base membrane's closure temperature. At this temperature, the polymer material closes the channels through which ions pass, reducing the membrane's thermal closure temperature and improving its thermal pore-closing function. This, in turn, helps mitigate thermal runaway and improves battery safety. By selecting the aforementioned first and second inorganic materials, which possess good heat resistance, the thermal stability of the membrane is improved, and the membrane rupture temperature is reduced to some extent. This reduces membrane shrinkage and rupture at the thermal closure temperature, thus lowering the risk of short circuits between the positive and negative electrodes and enhancing battery safety. By including water as both the first and second solvents, the aqueous slurry exhibits better compatibility during battery preparation and helps reduce costs. By selecting the aforementioned materials for the first binder, second binder, first dispersant, second dispersant, first wetting agent, and second wetting agent, the first and second slurries maintain good dispersibility.

[0059] To address the aforementioned technical problems, a third aspect of this application provides a diaphragm, comprising a base membrane and a first coating disposed on at least one side of the base membrane; the first coating comprises a polymer material, wherein the polymer material has a melting point or glass transition temperature of 90°C-140°C and a median particle size of 10 nm-10 μm.

[0060] By setting the melting point or glass transition temperature of the polymer material to 90℃-140℃, the polymer material melts at a temperature lower than the thermal closure temperature of the base film. The thermal closure temperature refers to the temperature at which the base film melts or shrinks, closing the channels that allow ions to pass through. The first coating melts before the base film when the separator temperature rises, closing the ion channels and reducing the separator's thermal closure temperature. This helps mitigate thermal runaway and improves battery safety. Simultaneously, under the heating or pressurizing conditions of hot pressing, baking, and formation processes during the assembly of the separator with the positive and negative electrodes, the separator has not yet reached its thermal closure temperature and remains in an effective state, maintaining the battery's electrical performance. This approach has good practical application prospects. By setting the median particle size Dv50 of the polymer material to 10nm-10μm, the pore structure of the first coating is suitable, which can allow ions to pass through smoothly during battery use, and can also quickly close the channels on the base film and the first coating that allow ions to pass through when the internal temperature of the battery reaches 90℃-140℃, thereby reducing battery thermal runaway, improving battery thermal stability, and helping to improve battery safety.

[0061] To address the aforementioned technical problems, a fourth aspect of this application provides a battery device comprising a battery cell according to any of the above-mentioned methods, or a battery cell prepared by a method according to any of the above-mentioned methods. The method for preparing the battery cell has at least the same advantages as the aforementioned battery cell.

[0062] To address the aforementioned technical problems, a fifth aspect of this application provides an electrical device comprising a battery device as described above, or a battery cell of any of the above-described embodiments, or a battery cell prepared by a method thereof. The electrical device possesses at least the same advantages as the aforementioned battery cell.

[0063] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0064] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0065] Figure 1 This is an exploded structural diagram of a battery cell provided in an embodiment of this application;

[0066] Figure 2 This is a schematic diagram of the structure of the first embodiment of the diaphragm provided in this application;

[0067] Figure 3 This is a schematic diagram of the second embodiment of the diaphragm provided in this application.

[0068] Figure 4 This is a schematic diagram of the third embodiment of the diaphragm provided in this application;

[0069] Figure 5 This is a schematic flowchart of the method for preparing a single battery cell provided in the embodiments of this application;

[0070] Figure 6 yes Figure 5 The flowchart of the separator preparation method in the preparation method of the battery cell is shown.

[0071] Figure 7 This is a schematic diagram of the battery device provided in the embodiments of this application;

[0072] Figure 8 This is a schematic diagram of the vehicle structure provided in an embodiment of this application. Detailed Implementation

[0073] To make the objectives, technical solutions, and effects of this application clearer and more explicit, the embodiments of the technical solutions of this application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of this application, and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0074] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0075] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces), unless otherwise explicitly specified.

[0076] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0077] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0078] Quantities, ratios, and other numerical values ​​are presented in range format in this document. It should be understood that this range format is for convenience and brevity and should be interpreted flexibly to include not only numerical values ​​explicitly specified as range limits, but also all individual numerical values ​​or subranges covered within the range, as if each numerical value and subrange were explicitly specified.

[0079] Unless otherwise specified, all steps of this application may be performed sequentially, randomly, or in parallel, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially, or steps (a) and (b) may be performed simultaneously in parallel. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or steps (a), (c), and (b), or steps (c), (a), and (b), etc.

[0080] Battery thermal stability is one of the key areas for technological improvement. A battery typically consists of a positive electrode, a negative electrode, and a separator. The separator's thermal closure function is a special protective mechanism that plays a crucial role in the battery's thermal stability. Specifically, the separator material can rapidly melt or shrink under abnormally high temperatures (such as localized overheating caused by an internal short circuit), forming a thermal fuse mechanism. This closes or reduces ion channels, decreasing ion migration between the positive and negative electrodes, effectively preventing further increases in internal battery temperature, reducing the risk of thermal runaway, and improving battery safety. Therefore, the separator's thermal closure temperature has a significant impact on battery safety.

[0081] Currently, one approach to improve the thermal closure function of the diaphragm is: 1) mixing high molecular weight polyethylene, a pore-forming agent, an antioxidant, a crosslinking agent, and a photoinitiator, and stirring until homogeneous to form a mixture, wherein the average molecular weight of the high molecular weight polyethylene is between 10.0 × 10⁻⁶. 4 -1000×10 4 The density is between 0.940 and 0.976 g / cm³. 3 The process involves: 1) mixing high molecular weight polyethylene (HMWPE), antioxidants, crosslinking agents, and photoinitiators in a pore-forming agent at a specific temperature using a twin-screw extrusion process; 2) casting the mixture extruded in step 2) into a strip; 3) extracting the pore-forming agent from the strip, stretching the strip to form a film, and then performing a second extraction followed by cleaning; 4) performing heat setting and winding steps to obtain an uncrosslinked separator film; and 5) subjecting the uncrosslinked separator film to light irradiation to obtain a photoinitiated crosslinked polymer separator film. The obtained photoinitiated crosslinked polymer separator film has a pore-closing temperature to rupture temperature difference of 30–60°C and a minimum heat shrinkage rate of 0.5%, showing significant improvements in both the rupture temperature to pore-closing temperature difference and the heat shrinkage rate. However, this method requires combining multiple materials, including HMWPE, antioxidants, crosslinking agents, and photoinitiators, during the preparation process. The compatibility of polymers with different structures and physical properties varies, making the separator manufacturing process complex and unstable, which in turn affects the consistency of the separator product.

[0082] Another approach to improve the thermal closure function of the diaphragm is to blend PP resin and a nucleating agent at the melting temperature of PP resin to form a core melt; and blend PE resin and a pore-forming agent at the melting temperature of PE resin to form a surface melt. The core melt is then co-extruded through the core outlet of a die, and the surface melt through two surface outlets of the die to form a membrane. This membrane is then subjected to longitudinal stretching, transverse stretching, extraction, and heat setting to form a three-layer PE-PP-PE separator membrane. The surface layer is a low-melting-point, low-molecular-weight PE layer, thus exhibiting low pore-closing temperature and fast pore-closing speed. However, this approach involves a relatively complex manufacturing process, which may hinder the maintenance of membrane product consistency.

[0083] In view of this, embodiments of this application provide a battery cell and its preparation method, a separator, a battery device, and an electrical device to improve the thermal stability of the battery. At the same time, it reduces the complexity of the separator manufacturing process and helps to improve the consistency of separator products.

[0084] Please see Figure 1 , Figure 1 This is an exploded structural diagram of a battery cell provided in an embodiment of this application.

[0085] The battery cell 20 includes an end cap 21, a housing 22, a cell assembly 23, and other functional components.

[0086] End cap 21 refers to a component that covers the opening of housing 22 to isolate the internal environment of battery cell 20 from the external environment. In any case, the shape of end cap 21 can be adapted to the shape of housing 22 to fit it. Optionally, end cap 21 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that end cap 21 is less prone to deformation under pressure and impact, enabling battery cell 20 to have higher structural strength and improved stability.

[0087] The end cap 21 may be provided with functional components such as electrode terminals 21a. The electrode terminals 21a can be used to electrically connect with the cell assembly 23 for outputting or inputting electrical energy of the battery cell 20. In some embodiments, the end cap 21 may also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold.

[0088] The end cap 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. This application embodiment does not impose any special restrictions on this.

[0089] In some embodiments, an insulating element may be provided on the inner side of the end cap 21. The insulating element can be used to isolate the electrical connection components within the housing 22 from the end cap 21 to reduce the risk of short circuits. For example, the insulating element may be made of plastic, rubber, etc.

[0090] The housing 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can accommodate the cell assembly 23, electrolyte, and other components. The housing 22 and the end cap 21 can be independent components. An opening can be provided on the housing 22, and the end cap 21 can be used to close the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and the housing 22 can be integrated. Specifically, the end cap 21 and the housing 22 can form a common connecting surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 22, the end cap 21 closes the housing 22. The housing 22 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined according to the specific shape and size of the cell assembly 23. The material of the housing 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. This application embodiment does not impose any special limitations on this.

[0091] The cell assembly 23 is the component in the battery cell 20 where the electrochemical reaction occurs. The casing 22 may contain one or more cell assemblies 23. The cell assembly 23 includes a positive electrode, a negative electrode, and a separator, with the separator located between the positive and negative electrode. The positive and negative electrode are wound or stacked to form the cell assembly 23. The portions of the positive and negative electrode with active material constitute the main body of the cell assembly 23, while the portions without active material each constitute a tab 23a. The positive and negative tabs may be located together at one end of the main body or at opposite ends. During the charging and discharging process of the battery device 100, the positive and negative active materials react with the electrolyte, and the tabs 23a connect to the electrode terminals 21a to form a current loop.

[0092] In one embodiment, the electrolyte includes a lithium salt and a solvent. Optionally, the lithium salt includes one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate, potassium difluorophosphate, lithium difluorooxalate borate (LiBF2(C2O4), LiDFOB), lithium bis(oxalate borate) (LiB(C2O4)2, LiBOB), potassium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate. Optionally, the solvent includes one or more of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, 1,4-butylpropyl ester, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. Optionally, additives may be added to the electrolyte as needed. Electrolyte additives include, but are not limited to, one or more of fluoroethylene carbonate (FEC), ethylene ethylene carbonate (VC), or 1,3-propanesulfonate lactone (PS).

[0093] In one embodiment, the positive electrode sheet includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive active material, a positive binder, and a positive conductive agent.

[0094] In one embodiment, the positive electrode current collector may be a metal foil or a composite positive electrode current collector. Optionally, the metal foil may be made of aluminum, copper, nickel, titanium, silver, or their corresponding alloys. Optionally, the composite positive electrode current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite positive electrode current collector may be formed by forming a metal material on a polymer material substrate; the metal material may include at least one of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy; the polymer material may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0095] In one embodiment, the thickness of the positive electrode current collector is 1 μm-30 μm. The thickness of the positive electrode current collector can be 1 μm, 3 μm, 5 μm, 10 μm, 15 μm, 16 μm, 20 μm, 25 μm, 30 μm, etc., or it can be a range of any two of the above values, for example, 10 μm-16 μm, 5 μm-20 μm.

[0096] In one embodiment, the battery is a lithium-ion battery, and the positive electrode active material includes, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates with an olivine structure, and their respective modified compounds. It should be noted that the modified compounds of the positive electrode active material can be those used for doping and / or surface coating modification of the positive electrode active material.

[0097] Optionally, the positive electrode active material may include materials with the general formula Li a Ni b Co c M d O e A f One or more of lithium transition metal oxides and their modified compounds. 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes one or more of N, F, S and Cl.

[0098] Optionally, the lithium transition metal oxide may include one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds.

[0099] Optionally, the lithium phosphate with an olivine structure may include one or more of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their respective modified compounds.

[0100] Optionally, the positive electrode active material may include LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 Co 0.15 Al 0.05 One or more of O2, LiFePO4 and LiMnPO4.

[0101] In one embodiment, when the battery is a sodium-ion battery, the positive electrode active material may include, but is not limited to, one or more of sodium-containing transition metal oxides, polyanionic materials, and Prussian blue materials.

[0102] Optionally, the polyanionic material includes one or more of phosphates, fluorophosphates, pyrophosphates, and sulfates.

[0103] Optionally, the positive electrode active material may include NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, NaNi 1 / 2 Ti 1 / 2O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue materials and materials with the general formula X p M' q (PO4) r O x Y 3-x One or more of the materials. In general formula X p M' q (PO4) r O x Y 3-x In the given condition, 0 < p ≤ 4, 0 < q ≤ 2, 1 ≤ r ≤ 3, 0 ≤ x ≤ 2, and X includes H. + Li + Na + K + and NH4 + One or more of the following, M' is a transition metal cation, and M' may include one or more of V, Ti, Mn, Fe, Co, Ni, Cu and Zn, and Y is a halide anion, and Y may include one or more of F, Cl and Br.

[0104] In one embodiment, the positive electrode binder includes one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and copolymers of PVDF and PTFE.

[0105] In one embodiment, the positive electrode conductive agent includes one or more of superconducting carbon, acetylene black, carbon black, carbon nanotubes, graphene, and carbon nanofibers.

[0106] In one specific embodiment, the positive electrode sheet is prepared by dispersing the positive active material, conductive agent, binder and any other components in a solvent (e.g., N-methylpyrrolidone NMP), stirring in a dry environment to form a uniform positive slurry, coating the positive slurry onto a positive current collector, and then drying and rolling to form a positive electrode sheet.

[0107] In one embodiment, the negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector. The negative electrode film layer includes a negative electrode active material, a negative electrode binder, a negative electrode thickener, and a negative electrode conductive agent.

[0108] In one embodiment, the negative electrode current collector may be a metal foil or a composite negative electrode current collector. Optionally, the metal foil may be made of aluminum, copper, nickel, titanium, silver, or their corresponding alloys. Optionally, the composite negative electrode current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite negative electrode current collector may be formed by forming a metal material on the polymer material substrate; the metal material may include at least one of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy; the polymer material may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0109] In one embodiment, the thickness of the negative electrode current collector is 1μm-20μm. The thickness of the negative electrode current collector can be 1μm, 3μm, 4μm, 5μm, 10μm, 15μm, 16μm, 20μm, etc., or it can be a range of any two of the above values, for example, 4μm-10μm, 5μm-16μm.

[0110] In one embodiment, the negative electrode active material includes, but is not limited to, at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. 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.

[0111] In one embodiment, the negative electrode binder includes one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and polymethacrylic acid (PMAA).

[0112] In one embodiment, the negative electrode thickener includes at least one of sodium carboxymethyl cellulose (CMC-Na) and lithium carboxymethyl cellulose (CMC-Li).

[0113] In one embodiment, the negative electrode conductive agent includes one or more of superconducting carbon, acetylene black, carbon black, carbon nanotubes, graphene, and carbon nanofibers.

[0114] In one specific embodiment, the negative electrode active material, negative electrode binder, negative electrode thickener, negative electrode conductive agent and any other components are dispersed in a solvent (e.g., deionized water), stirred in a dry environment to form a uniform negative electrode slurry, the negative electrode slurry is coated on a negative electrode current collector, and then dried and rolled to form a negative electrode sheet.

[0115] Please see Figure 2 , Figure 2 This is a schematic diagram of the structure of the first embodiment of the diaphragm provided in this application.

[0116] In one embodiment, the diaphragm includes a base membrane 41 and a first coating 42 disposed on at least one side of the base membrane 41. The first coating 42 includes a polymer material having a melting point or glass transition temperature of 90°C-140°C and a median particle size of 10 nm-10 μm.

[0117] The base membrane 41 is the supporting structural layer of the diaphragm and is a fundamental component of the diaphragm. The base membrane 41 is a porous membrane that provides channels for the passage of ions. The first coating 42 is a membrane layer that improves the performance of the diaphragm.

[0118] By providing a first coating 42 on at least one side of the base film 41, and the first coating 42 comprising a polymer material with a melting point or glass transition temperature (Tg) of 90°C-140°C, the polymer material is in a molten state when the internal temperature of the battery reaches 90°C-140°C. The molten polymer material has strong fluidity, which closes the channels on the base film 41 and the first coating 42 that allow ions to pass through, increasing the internal resistance of the battery, reducing thermal runaway caused by excessive temperature and current, and improving the thermal stability of the battery. Furthermore, forming the first coating 42 on at least one side of the base film 41 is simple and easy to implement; for example, coating and deposition processes are simple to operate, and the resulting separator product has good consistency.

[0119] By setting the melting point or glass transition temperature of the polymer material to 90℃-140℃, the temperature at which the polymer material becomes molten is lower than the thermal closure temperature of the base film 41. The thermal closure temperature refers to the temperature at which the base film melts or shrinks, closing the channels that allow ions to pass through. When the separator temperature rises, the first coating 42 becomes molten before the base film 41, closing the ion channels and reducing the thermal closure temperature of the separator. This helps to mitigate thermal runaway and improve battery safety. Simultaneously, under the heating or pressurizing conditions of hot pressing, baking, and formation processes during the assembly of the separator with the positive and negative electrodes, the separator has not yet reached its thermal closure temperature and remains in an effective state, maintaining the battery's electrical performance and demonstrating good practical application prospects.

[0120] By setting the median particle size Dv50 of the polymer material to 10nm-10μm, the pore structure of the first coating 42 is suitable, which can allow ions to pass through smoothly during battery use, and can also quickly close the channels on the base film 41 and the first coating 42 that allow ions to pass through when the internal temperature of the battery reaches 90℃-140℃, thereby reducing battery thermal runaway, improving battery thermal stability, and helping to improve battery safety.

[0121] The melting point or glass transition temperature of polymer materials can be 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, etc., or it can be a range of any two of the above values, such as 90℃-120℃, 110℃-130℃, etc.

[0122] The volume median particle size Dv50 of polymer materials can be 10nm, 50nm, 100nm, 500nm, 1000nm, 5μm, 10μm, etc., or it can be a range composed of any two of the above values, such as 100nm-5μm, 10nm-500nm, etc.

[0123] Optionally, the first coating 42 is disposed on the surface of the base film 41, so that when the internal temperature of the battery reaches 90℃-140℃, the first coating 42 has a good closing effect on the channels on the base film 41 that allow ions to pass through. For example, the base film 41 includes a first surface and a second surface disposed opposite to each other, and the first surface of the base film 41 is provided with the first coating 42. For example, the base film 41 includes a first surface and a second surface disposed opposite to each other, and the first surface and the second surface of the base film 41 are respectively provided with the first coating 42.

[0124] Optionally, the orthographic projection of the first coating 42 onto the base film 41 completely overlaps with the base film 41, so that when the internal temperature of the battery reaches 90℃-140℃, the first coating 42 has a closing effect on the channels through which ions pass at various positions of the base film 41.

[0125] In one embodiment, the melting point or glass transition temperature of the polymer material is 100°C-130°C.

[0126] The above settings help to further reduce the thermal closure temperature of the separator, improve the thermal pore-closing function of the separator, thereby helping to reduce the thermal runaway of the battery and improve the battery safety. At the same time, under the heating or pressurization conditions of hot pressing, baking, and formation processes during the assembly of the separator with the positive and negative electrode plates, the separator does not reach the thermal closure temperature, reducing the impact of the separator on ion transport and maintaining better electrical performance of the battery.

[0127] The melting point or glass transition temperature of polymer materials can be 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, etc., or it can be a range of any two of the above values, such as 105℃-125℃, 110℃-130℃, etc.

[0128] In one embodiment, the bulk median particle size of the polymer material is 300 nm to 2 μm.

[0129] By setting the median particle size Dv50 of the polymer material to 300nm-2μm, the pore structure of the first coating 42 is suitable, which can maintain smooth ion transport during battery use, and can also quickly close the channels on the base film 41 and the first coating 42 that allow ions to pass through when the internal temperature of the battery reaches the closure temperature, thereby reducing battery thermal runaway, improving battery thermal stability, and improving battery safety.

[0130] The volume median particle size Dv50 of polymer materials can be 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, 1.5μm, 2μm, etc., or it can be a range composed of any two of the above values, such as 800nm-1.5μm, 900nm-2μm, etc.

[0131] In one embodiment, the density of the polymer material is 0.1 g / cm³. 3 -10g / cm 3 .

[0132] By setting the density of the polymer material to 0.1 g / cm³ 3 -10g / cm 3During the process of forming the first coating 42 using an aqueous slurry, the polymer material has good dispersion in the slurry, which is beneficial to maintaining the uniformity of the polymer material covering the base membrane 41. When the internal temperature of the battery reaches the pore-closing temperature of the separator, the polymer material can quickly close the ion channels at various locations. The good dispersion of the polymer material in the slurry is beneficial to maintaining the consistency of the first coating 42 and the consistency of the product separator during the mass production of separators.

[0133] The density of polymer materials can be 0.1 g / cm³. 3 0.5g / cm 3 1g / cm 3 2g / cm 3 3g / cm 3 4g / cm 3 5g / cm 3 6g / cm 3 7g / cm 3 8g / cm 3 9g / cm 3 9g / cm 3 etc., or 0.5g / cm 3 -5g / cm 3 1g / cm 3 -8g / cm 3 wait.

[0134] In one embodiment, the density of the polymer material is 0.5 g / cm³. 3 -2g / cm 3 .

[0135] By setting the density of the polymer material to 0.5 g / cm³ 3 -2g / cm 3 During the process of forming the first coating 42 using an aqueous slurry, the polymer material is well dispersed in the slurry, and the polymer material covers the base membrane 41 more evenly. When the internal temperature of the battery reaches the pore-closing temperature of the separator, the polymer material can quickly close the ion channels at various locations. The good dispersion of the polymer material in the slurry helps to maintain the consistency of the first coating 42 and the consistency of the product separator during the mass production of separators.

[0136] The density of the polymer material can be 0.5 g / cm³. 3 0.6g / cm 3 0.7g / cm 3 0.8g / cm 3 0.9g / cm 3 1g / cm 3 1.1g / cm 31.2g / cm 3 1.3g / cm 3 1.4g / cm 3 1.5g / cm 3 1.6g / cm 3 1.7g / cm 3 1.8g / cm 3 1.9g / cm 3 2g / cm 3 It can also be 0.9 g / cm³. 3 -1.5g / cm 3 0.6g / cm 3 -1.3g / cm 3 wait.

[0137] In one embodiment, the polymer material includes at least one of polyacrylic acid, polymethyl methacrylate and its derivatives, polyvinylidene fluoride, acrylonitrile-butadiene-styrene copolymer, carboxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, styrene-acrylic rubber, polyacrylonitrile, polyvinyl acetal, polylactic acid, polylactic acid-glycolic acid copolymer, acrylate-vinyl acetate-styrene copolymer, and acrylate-vinyl acetate copolymer.

[0138] By selecting the aforementioned polymer material, the polymer material melts at a temperature lower than the closing temperature of the base film 41. At this temperature, the polymer material closes the channels through which ions pass, reducing the thermal closing temperature of the separator and improving its thermal pore-closing function. This, in turn, helps to reduce the thermal runaway of the battery and improve its safety.

[0139] In one embodiment, the first coating 42 further includes a first inorganic material, wherein the weight ratio of the polymer to the first inorganic material is 1-50 parts of the polymer and 1-50 parts of the first inorganic material.

[0140] By including the first inorganic material in the first coating 42 and setting the weight ratio between the polymer material and the first inorganic material as described above, the first inorganic material increases the porosity of the first coating 42, reducing the probability of partial ion channel closure caused by deformation of the polymer material under conditions such as heating or pressurization during the battery cell assembly manufacturing process. This helps maintain the smooth ion passage of the separator during the production process and normal use. By adding the first inorganic material, the mechanical strength of the first coating 42 can be enhanced by utilizing the properties of the first inorganic material, and the first coating 42 can also maintain structural integrity at the thermal closure temperature.

[0141] In one embodiment, the mass ratio of the polymer material to the first inorganic material in the first coating 42 is 1:6 to 6:1.

[0142] By setting the mass ratio between the polymer material and the first inorganic material as described above, the amount of the first inorganic material added is more suitable, which helps the first coating 42 maintain sufficient porosity and improves the stability of the first coating 42. It can maintain structural integrity at the thermal closure temperature, which helps to quickly close the ion channels when the thermal closure temperature is reached, hindering further ion migration, thereby improving the safety of the battery.

[0143] The mass ratio of the polymer material to the first inorganic material can be 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, etc., and can be a range of any two of the above mass ratios, such as 1:1-6:1, 2:1-6:1, etc.

[0144] In one embodiment, the volume median particle size Dv50 of the first inorganic material is 10 nm-10 μm.

[0145] By setting the median particle size Dv50 of the first inorganic material as described above, the first inorganic material is more uniformly dispersed in the polymer material, forming a dense mesh structure, maintaining the smoothness of ion transport, and when the thermal closure temperature is reached, the first coating 42 can quickly close the ion channel, which is beneficial to improving the safety of the battery.

[0146] The volume median particle size Dv50 of the first inorganic material can be 10nm, 50nm, 100nm, 500nm, 1000nm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, etc., or it can be a range composed of any two of the above values, such as 10nm-500nm, 100nm-5μm, etc.

[0147] In one embodiment, the volume median particle size Dv50 of the first inorganic material is 300 nm-2 μm.

[0148] By setting the median particle size Dv50 of the first inorganic material as described above, the first inorganic material is more evenly dispersed in the polymer material, forming a finer network structure. The thermal response of the material with the above-mentioned particle size is more rapid. When the thermal closure temperature is reached, the first coating 42 can close the ion channels more quickly, which is beneficial to improving the safety of the battery.

[0149] The volume median particle size Dv50 of the first inorganic material can be 300nm, 500nm, 1000nm, 1.1μm, 1.5μm, 2μm, etc., or it can be a range composed of any two of the above values, such as 300nm-500nm, 500nm-1.5μm, etc.

[0150] In one embodiment, the first inorganic material includes at least one of aluminum oxide, boehmite, barium sulfate, silicon dioxide, magnesium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, zirconium oxide, and titanium dioxide.

[0151] By selecting the aforementioned material as the first inorganic material, which has heat resistance and is not easily decomposed at the thermal closure temperature, it can serve as a thermal trigger point to enable the first coating 42 to quickly achieve thermal closure, thereby effectively reducing thermal runaway inside the battery and improving the battery's safety performance.

[0152] In one embodiment, the thickness of the first coating 42 is 0.5 μm to 4 μm.

[0153] By setting the thickness of the first coating 42 as described above, sufficient polymer material can be provided to effectively thermally close the ion channels, and the heat transfer is relatively fast, enabling rapid response to changes in battery temperature to achieve thermal closure.

[0154] The thickness of the first coating 42 can be 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, etc., or it can be a range of any two of the above values, such as 1μm-2.5μm, 0.5μm-1.5μm, etc.

[0155] In one embodiment, the thickness of the first coating 42 is 1.5 μm to 3 μm.

[0156] By setting the thickness of the first coating 42 as described above, sufficient polymer material can be provided to effectively thermally close the ion channels. At the same time, heat transfer is faster, and the thermal closure is achieved more quickly in response to changes in battery temperature.

[0157] The thickness of the first coating 42 can be 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, etc., or it can be a range of any two of the above values, such as 1.5μm-2.1μm, 1.8μm-2.9μm, etc.

[0158] It should be noted that the thickness of the separator formed by the base film 41 and the first coating 42 is approximately the same as the thickness of existing separators, and the thickness of the battery formed using the separator provided in this application embodiment is approximately the same as the thickness of existing batteries.

[0159] Please see Figure 3 and Figure 4 , Figure 3 This is a schematic diagram of the second embodiment of the diaphragm provided in this application. Figure 4This is a schematic diagram of the third embodiment of the diaphragm provided in this application.

[0160] In one embodiment, the diaphragm further includes a second coating 43, which comprises a second inorganic material. For example... Figure 3 As shown, the second coating 43 is disposed on the side of the first coating 42 facing away from the base film 41; or, as... Figure 4 As shown, the second coating 43 is disposed on the side of the base film 41 where the first coating 42 is not disposed.

[0161] By further configuring a second coating 43, which includes a second inorganic material with heat resistance, the separator can achieve thermal closure while maintaining its heat resistance, which is beneficial to improving the thermal stability of the separator. To a certain extent, it improves the membrane breakage temperature, reduces membrane shrinkage, and reduces the risk of short circuit between the positive and negative electrodes, thus improving the safety of the battery.

[0162] When the second coating 43 is disposed on the side of the first coating 42 away from the base film 41, when the internal temperature of the battery rises to the thermal closure temperature, the polymer material of the first coating 42 becomes molten and will be transformed into a strong adhesive layer between the base film 41 and the second coating 43, which enhances the stability of the adhesive interface between the base film 41 and the second coating 43, improves the thermal shrinkage performance of the separator, helps to improve the membrane breakage temperature of the separator, and improves the safety performance of the battery.

[0163] Optionally, when the second coating 43 is disposed on the side of the first coating 42 away from the base film 41, the second coating 43 is disposed on the surface of the first coating 42 away from the base film 41.

[0164] Optionally, when the second coating 43 is disposed on the side of the first coating 42 away from the base film 41, the second coating 43 completely covers the first coating 42.

[0165] Optionally, when the second coating 43 is disposed on the side of the base film 41 where the first coating 42 is not disposed, the second coating 43 is disposed on the surface of the base film 41.

[0166] Optionally, when the second coating 43 is disposed on the side of the base film 41 where the first coating 42 is not disposed, the second coating 43 completely covers the base film 41.

[0167] Optional, such as Figure 3 As shown, a first coating 42 and a second coating 43 are sequentially provided on one side of the base film 41.

[0168] Optional, such as Figure 4 As shown, a first coating 42 is provided on one side of the base film 41, and a second coating 43 is provided on the other side of the base film 41.

[0169] Optionally, a first coating 42 and a second coating 43 are sequentially provided on one side of the base film 41, and a first coating 42 and a second coating 43 are sequentially provided on the other side of the base film 41.

[0170] Optionally, a first coating 42 and a second coating 43 are sequentially provided on one side of the base film 41, and a second coating 43 is sequentially provided on the other side of the base film 41.

[0171] In one embodiment, the volume median particle size Dv50 of the second inorganic material is 10 nm-10 μm.

[0172] By setting the volume median particle size Dv50 of the second inorganic material as described above, the second inorganic material can form a relatively dense and stable second coating 43, which enhances the mechanical strength and thermal stability of the diaphragm. The second inorganic material with the above particle size can provide a larger specific surface area, which is conducive to heat transfer and dispersion, improves the thermal response speed, and helps to trigger the thermal closure performance of the first coating 42.

[0173] The volume median particle size Dv50 of the second inorganic material can be 10nm, 50nm, 100nm, 500nm, 1000nm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, etc., or it can be a range composed of any two of the above values, such as 10nm-500nm, 100nm-5μm, etc.

[0174] In one embodiment, the volume median particle size Dv50 of the second inorganic material is 300 nm-2 μm.

[0175] By setting the median particle size Dv50 of the second inorganic material as described above, the second inorganic material can form a more stable second coating 43, further enhancing the mechanical strength and thermal stability of the diaphragm; the second inorganic material with the above particle size can provide a larger specific surface area, which is conducive to heat transfer and dispersion, improves the thermal response speed, and helps to trigger the thermal closure performance of the first coating 42.

[0176] The volume median particle size Dv50 of the second inorganic material can be 300nm, 500nm, 1000nm, 1.1μm, 1.5μm, 2μm, etc., or it can be a range composed of any two of the above values, such as 300nm-500nm, 500nm-1.5μm, etc.

[0177] In one embodiment, the second inorganic material includes at least one of aluminum oxide, boehmite, barium sulfate, silicon dioxide, magnesium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, zirconium oxide, and titanium dioxide.

[0178] By selecting the aforementioned material as the second inorganic material, which has good heat resistance, the thermal stability of the separator can be improved. This can improve the membrane rupture temperature to a certain extent, reduce membrane shrinkage, and prevent membrane rupture at the thermal closure temperature. This reduces the risk of short circuit between the positive and negative electrodes and improves battery safety.

[0179] In one embodiment, the thickness of the second coating 43 is 0.5 μm to 4 μm.

[0180] By setting the thickness of the second coating 43 as described above, the membrane maintains high mechanical strength and thermal stability. At the same time, it can transfer heat relatively quickly, so that the first coating 42 can quickly close the ion channel when the battery temperature reaches the thermal closure temperature, reducing the risk of thermal runaway.

[0181] The thickness of the second coating 43 can be 0.5μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, etc., or it can be a range of any two of the above values, such as 1μm-2.5μm, 0.5μm-1.5μm, etc.

[0182] In one embodiment, the thickness of the second coating 43 is 1.5 μm to 3 μm.

[0183] By setting the thickness of the second coating 43 as described above, the membrane maintains high mechanical strength and thermal stability. At the same time, it can transfer heat more quickly, so that the first coating 42 can quickly close the ion channel when the battery temperature reaches the thermal closure temperature, reducing the risk of thermal runaway.

[0184] The thickness of the second coating 43 can be 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, etc., or it can be a range of any two of the above values, such as 1.5μm-2.1μm, 1.8μm-2.9μm, etc.

[0185] In one embodiment, a base film 41 is provided with a multilayer first coating 42 and a multilayer second coating 43 on one side, with the first coating 42 and the second coating 43 being stacked alternately.

[0186] In one embodiment, the thickness of the base film 41 is 1 μm-30 μm.

[0187] By setting the thickness of the base film 41 as described above, the internal resistance of the separator is appropriate, maintaining smooth ion transport; it also has good mechanical strength and puncture resistance, which can reduce the risk of short circuits caused by external forces and improve battery safety.

[0188] The thickness of the base film 41 can be 1μm, 2μm, 4μm, 6μm, 8μm, 10μm, 15μm, 20μm, 25μm, 30μm, etc., or it can be a range of any two of the above values, such as 1μm-6μm, 4μm-15μm, etc.

[0189] It should be noted that the thickness of the separator formed by the base film 41, the first coating 42, and the second coating 43 is approximately the same as the thickness of existing separators, and the thickness of the battery formed using the separator provided in this application embodiment is approximately the same as the thickness of existing batteries.

[0190] In one embodiment, the porosity of the base membrane 41 is 10%-80%.

[0191] By setting the porosity of the base membrane 41 as described above, the membrane can better absorb and retain the electrolyte, ensuring that there is enough electrolyte inside the battery to participate in the electrochemical reaction, thereby improving battery performance.

[0192] The porosity of the base membrane 41 can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, etc., or it can be a range of any two of the above numbers, such as 50%-80%, 30%-70%, etc.

[0193] In one embodiment, the base film 41 includes at least one of polyethylene film, polypropylene film, polyethylene-polypropylene composite film, polyimide film, and polyester film.

[0194] By designing the base membrane 41 and selecting the aforementioned materials, it is found to have good mechanical strength, enabling the separator to provide good mechanical support for the battery.

[0195] For example, the material of the base film 41 includes a polypropylene film (PP), the heat-closing temperature of the polypropylene film is 160°C-170°C, the melting point or glass transition temperature of the polymer of the first coating 42 is 90°C-140°C, the heat-closing temperature of the first coating 42 is lower than the heat-closing temperature of the base film 41, which reduces the heat-closing temperature of the separator, which helps to reduce the thermal runaway of the battery and improve the safety of the battery.

[0196] For example, the material of the base film 41 includes a polyethylene film (PE) with a thermal closure temperature of 130°C-140°C. The polymer of the first coating 42 has a melting point or glass transition temperature of 100°C-130°C. The thermal closure temperature of the first coating 42 is lower than that of the base film 41, which reduces the thermal closure temperature of the separator, which helps to reduce the thermal runaway of the battery and improve the safety of the battery.

[0197] In one embodiment, the diaphragm includes a base membrane 41, a first coating 42, and a second coating 43. The first coating 42 is disposed on the surface of the base membrane 41, and the second coating 43 is disposed on the surface of the first coating 42 facing away from the base membrane 41. The first coating 42 comprises an acrylate-vinyl acetate-styrene copolymer and alumina. The second coating 43 comprises alumina.

[0198] Please see Figure 5 and Figure 6 , Figure 5 This is a schematic flowchart of the method for preparing a single battery cell provided in the embodiments of this application. Figure 6 yes Figure 5 The diagram shows a flow chart of the separator preparation method in the preparation method of the battery cell.

[0199] This application also provides a method for preparing a battery cell, which can be used to prepare the battery cell provided in the above embodiments. The method for preparing the battery cell specifically includes:

[0200] Step S01: The negative electrode, separator and positive electrode are stacked in sequence to form a cell assembly.

[0201] Specifically, the steps for forming a battery cell assembly include: sequentially preparing a positive electrode sheet, a negative electrode sheet, and a separator; alternately stacking the positive and negative electrode sheets; and placing a separator between the positive and negative electrode sheets to provide isolation, thereby obtaining a battery cell assembly. Alternatively, the battery cell assembly can be obtained by winding.

[0202] The methods for preparing the diaphragm include:

[0203] Step S011: Provide a base film.

[0204] Specifically, the base membrane is the supporting structural layer of the diaphragm and is a fundamental component of the diaphragm. The base membrane is a porous membrane that provides channels for ion movement. Optionally, the base membrane includes at least one of polyethylene membrane, polypropylene membrane, polyethylene-polypropylene composite membrane, polyimide membrane, and polyester membrane.

[0205] Step S012: Coat at least one side of the base film with a first slurry to form a first coating; the first slurry includes a polymer material, the polymer material having a melting point or glass transition temperature of 90℃-140℃; and the polymer material having a median particle size of 10nm-10μm.

[0206] Specifically, a first coating is formed on one side of the base membrane by coating, which reduces the thermal closing temperature of the diaphragm and improves the diaphragm performance.

[0207] Step S02: Place the battery cell assembly in the housing.

[0208] Specifically, the housing is a component used to form an internal environment that can accommodate the battery cell assembly. The shape of the housing can be determined according to the specific shape and size of the battery cell assembly. The housing can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose any special limitations on this.

[0209] Step S03: Inject electrolyte into the casing and seal it to form a battery cell.

[0210] Specifically, the internal environment formed by the casing also serves to contain the electrolyte, which affects battery performance. The electrolyte provides pathways for ions to move between the positive and negative electrodes, promoting the charging and discharging process of the battery. The specific composition of the electrolyte is designed according to needs. The electrolyte is injected into the casing and sealed to obtain a single battery cell.

[0211] By employing the above preparation method, the coating process is simple to operate, and the resulting separator product exhibits good consistency. The melting point or glass transition temperature of the polymer material in the first coating 42 is 90℃-140℃, ensuring that when the internal temperature of the battery reaches 90℃-140℃, the polymer material is in a molten state. The molten polymer material has strong fluidity, which closes the channels on the base film 41 and the first coating 42 that allow ions to pass through, thereby increasing the internal resistance of the battery, reducing thermal runaway caused by excessive temperature and current, and improving the thermal stability of the battery.

[0212] Optionally, a first slurry can be coated on one side of the base film using processes such as spraying, roller coating, or dip coating, depending on the specific requirements.

[0213] In one embodiment, the first slurry further includes a first inorganic material, a first binder, a first dispersant, a first wetting agent, and a first solvent. The weight ratio of the polymer material, the first inorganic material, the first binder, the first dispersant, the first wetting agent, and the first solvent is as follows: 1 part to 50 parts of polymer material, 1 part to 50 parts of first inorganic material, 1 part to 10 parts of first binder, 0.1 part to 2 parts of first dispersant, 0.01 part to 1 part of first wetting agent, and 1 part to 80 parts of first solvent.

[0214] By setting the components and their proportions as described above, the uniform dispersion of the first inorganic material and polymer material in the first slurry is maintained. The first inorganic material increases the porosity of the first coating 42, reducing the probability of partial ion channel closure caused by deformation of the polymer material under heating or pressurization conditions during the battery cell assembly manufacturing process. This helps maintain the smooth flow of ions through the separator during production and normal use. Furthermore, by adding the first inorganic material, the mechanical strength of the first coating 42 can be enhanced, and the first coating 42 can maintain its structural integrity even at thermal closure temperatures.

[0215] Optionally, the total weight of the first slurry is 100 parts.

[0216] Optionally, the total weight of the first slurry is 100.4 parts.

[0217] In one embodiment, the first slurry is prepared by: dissolving a first dispersant in a first solvent to form a uniformly dispersed solution; adding a polymer material and a first inorganic material to the solution and stirring to disperse them into a uniform mixture; adding a first binder and a first wetting agent to the mixture and stirring to disperse them uniformly to obtain the first slurry. By first dispersing and dissolving the first dispersant and then adding the polymer material and the first inorganic material, it is beneficial to ensure the full dispersion of the polymer material and the first inorganic material.

[0218] In one embodiment, the method for preparing the diaphragm further includes: coating a second slurry on the side of the first coating away from the base film or on the side of the base film where the first coating is not provided, to form a second coating; wherein the second slurry includes a second inorganic material, a second binder, a second dispersant, a second wetting agent, and a second solvent; the weight ratio of the second inorganic material, the second binder, the second dispersant, the second wetting agent, and the second solvent is: 1 part to 80 parts of the second inorganic material, 1 part to 10 parts of the second binder, 0.1 part to 2 parts of the second dispersant, 0.01 part to 1 part of the second wetting agent, and 1 part to 80 parts of the second solvent.

[0219] The second coating is formed by coating, which is simple to operate and helps maintain the consistency of the resulting separator product. By setting the components and proportions of the second slurry as described above, the dispersion uniformity of the second inorganic material in the second slurry is maintained. The second inorganic material has heat resistance properties, enabling the separator to achieve thermal closure while maintaining its heat resistance, which helps improve the thermal stability of the separator. To a certain extent, this improves the membrane rupture temperature, reduces membrane shrinkage, and minimizes the risk of membrane rupture at the thermal closure temperature, thus reducing the risk of short circuits between the positive and negative electrodes and improving battery safety.

[0220] Optionally, a second slurry may be applied to the side of the first coating away from the base film or to the side of the base film where the first coating is not applied. Spraying, roller coating, dip coating, or other processes may be used, depending on the specific requirements.

[0221] Optionally, the total weight of the second slurry is 100 parts.

[0222] Optionally, the total weight of the second slurry is 100.4 parts.

[0223] In one embodiment, the second slurry is prepared by: dissolving a second dispersant in a second solvent to form a uniformly dispersed solution; adding a second inorganic material to the solution and stirring to disperse it into a uniform mixture; adding a second binder and a second wetting agent to the mixture and stirring to disperse it uniformly to obtain the second slurry. By first dispersing and dissolving the second dispersant and then adding the second inorganic material, it is beneficial to fully disperse the second inorganic material.

[0224] In one embodiment, the polymer material includes at least one of polyacrylic acid, polymethyl methacrylate and its derivatives, polyvinylidene fluoride, acrylonitrile-butadiene-styrene copolymer, carboxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, styrene-acrylic rubber, polyacrylonitrile, polyvinyl acetal, polylactic acid, polylactic-glycolic acid copolymer, and acrylate-vinyl acetate-styrene copolymer; and / or, the first inorganic material and the second inorganic material each independently include at least one of alumina, boehmite, barium sulfate, silicon dioxide, magnesium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, zirconium oxide, and titanium dioxide. ; and / or, the first adhesive and the second adhesive each independently include at least one of polyacrylic acid, polyacrylate, styrene-butadiene rubber, styrene-acrylic emulsion, polyurethane, and polyacrylonitrile; and / or, the first dispersant and the second dispersant each independently include at least one of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, sodium polyacrylate, and polyacrylamide; and / or, the first wetting agent and the second wetting agent each independently include at least one of alkyl alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, polyoxyethylene ether, alkylbenzene sulfonate, and alkyl sulfate; and / or, the first solvent and the second solvent each independently include water.

[0225] By selecting the aforementioned polymer materials, the polymer material melts at a temperature lower than the base membrane's closure temperature. At this temperature, the polymer material closes the channels through which ions pass, reducing the membrane's thermal closure temperature and improving its thermal pore-closing function. This, in turn, helps mitigate thermal runaway and improves battery safety. By selecting the aforementioned first and second inorganic materials, which possess good heat resistance, the thermal stability of the membrane is improved, and the membrane rupture temperature is reduced to some extent. This reduces membrane shrinkage and rupture at the thermal closure temperature, thus lowering the risk of short circuits between the positive and negative electrodes and enhancing battery safety. By including water as both the first and second solvents, the aqueous slurry exhibits better compatibility during battery preparation and helps reduce costs. By selecting the aforementioned materials for the first binder, second binder, first dispersant, second dispersant, first wetting agent, and second wetting agent, the first and second slurries maintain good dispersibility.

[0226] In one specific embodiment, a first slurry is formed by selecting 15 parts by weight of acrylate-vinyl acetate-styrene copolymer (Dv50 = 0.6 μm, Tg = 90 °C), 15 parts by weight of alumina particles (Dv50 = 1 μm), 64.2 parts by weight of deionized water, 4 parts by weight of polyacrylate, 1 part by weight of sodium polyacrylate, 1 part by weight of sodium carboxymethyl cellulose, and 0.2 parts by weight of fatty alcohol polyoxyethylene ether.

[0227] In one specific embodiment, a second slurry is formed by selecting 30 parts by weight of alumina, 64.2 parts by weight of deionized water, 4 parts by weight of polyacrylate, 1 part by weight of sodium polyacrylate, 1 part by weight of sodium carboxymethyl cellulose, and 0.2 parts by weight of fatty alcohol polyoxyethylene ether.

[0228] Please see Figure 7 , Figure 7 This is a schematic diagram of the battery device provided in the embodiments of this application.

[0229] The battery device 100 includes a housing 10 and battery cells 20, with the battery cells 20 housed within the housing 10. The battery cell 20 refers to the smallest unit constituting the battery device 100. The battery cell 20 can be the battery cell provided in the above embodiments, or it can be a battery cell prepared by the method described in the above embodiments.

[0230] The housing 10 provides a space for accommodating the battery cell 20, and can adopt various structures. In some embodiments, the housing 10 may include a first part 11 and a second part 12, which overlap each other, and together define a space for accommodating the battery cell 20. The second part 12 may be a hollow structure with one open end, and the first part 11 may be a plate-like structure, covering the open side of the second part 12 so that the first part 11 and the second part 12 together define the space; alternatively, the first part 11 and the second part 12 may both be hollow structures with one open side, with the open side of the first part 11 covering the open side of the second part 12. Of course, the housing 10 formed by the first part 11 and the second part 12 can be of various shapes, such as a cylinder, a cuboid, etc.

[0231] In the battery device 100, there can be multiple battery cells 20. These multiple battery cells 20 can be connected in series, in parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, in parallel, or in a mixed configuration, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery device 100 can also be composed of multiple battery cells 20 first connected in series, in parallel, or in a mixed configuration to form a battery module, and then multiple battery modules are connected in series, in parallel, or in a mixed configuration to form a whole, which is then housed within the housing 10.

[0232] The battery device 100 may also include other structures, for example, the battery device 100 may also include a busbar for realizing electrical connection between multiple battery cells 20.

[0233] Each battery cell 20 can be a secondary battery. The battery cell 20 can be cylindrical, flat, cuboid, or other shapes.

[0234] The battery device disclosed in this application can be used in electrical devices that use batteries as a power source or in various energy storage systems that use batteries as energy storage elements. The electrical device includes the battery device provided in the above embodiments, the battery cell provided in the above embodiments, or the battery cell provided in the above embodiments, prepared by the same method. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0235] For ease of explanation, the following embodiments use a vehicle 1000 as an example of an electrical device according to an embodiment of this application. Please refer to... Figure 8, Figure 8 This is a schematic diagram of the vehicle structure provided in an embodiment of this application.

[0236] Vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 100 is installed inside vehicle 1000, which can be located at the bottom, front, or rear of vehicle 1000. The battery device 100 can be used to power vehicle 1000; for example, it can serve as the operating power source for vehicle 1000. Vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 controls the battery device 100 to supply power to the motor 300, for example, to meet the power needs of vehicle 1000 during starting, navigation, and driving.

[0237] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0238] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, the following will provide a more detailed description in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0239] The preparation process of Example 1 is as follows:

[0240] (1) Preparation of positive electrode sheet:

[0241] (a) Obtain the positive current collector aluminum foil with a thickness of 10 μm.

[0242] (b) The positive electrode active material NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2, polyvinylidene fluoride (PVDF), and conductive carbon are added to N-methylpyrrolidone (NMP) in a mass percentage ratio of 97.5:1.5:1, and stirred in a dry environment to form a homogeneous slurry, thus preparing the positive electrode active slurry. The positive electrode active slurry is then coated onto both surfaces of the positive electrode current collector aluminum foil to form the positive electrode active material layer.

[0243] (c) After drying and rolling, a negative electrode sheet is obtained.

[0244] (2) Preparation of negative electrode sheet:

[0245] (a) Obtain a copper foil for the negative electrode current collector with a thickness of 10 μm.

[0246] (b) The negative electrode active material graphite, sodium carboxymethyl cellulose (CMC), conductive black, and styrene-butadiene rubber (SBR) are added to deionized water in a weight percentage ratio of 96:1:1:2 and stirred to form a uniform slurry, thus preparing the negative electrode active slurry. The negative electrode active slurry is then coated onto the negative electrode current collector copper foil to form the negative electrode active material layer.

[0247] (c) After drying and cold pressing, a negative electrode sheet is obtained.

[0248] It should be noted that the coating amounts of the positive and negative electrodes satisfy the following formula: (96% × negative electrode coating amount × graphite specific capacity) / (97.5% × positive electrode coating amount × positive electrode specific capacity) = 1.1

[0249] (3) Preparation of electrolyte:

[0250] Ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. LiPF6 was dissolved in the organic solvent to prepare a LiPF6 solution with a concentration of 1 mol / L. Fluoroethylene carbonate (FEC) was then added to bring the mass fraction to 3 wt%.

[0251] (4) Preparation of the diaphragm:

[0252] (a) Obtaining the base film; the base film is made of polyethylene (PE), with a thickness of 7 μm and a porosity of 38%.

[0253] (b) Preparation of the first coating: A first slurry was prepared by using 15 parts by weight of acrylate-vinyl acetate-styrene copolymer (Dv50 = 0.6 μm, Tg = 90℃), 15 parts by weight of alumina particles (Dv50 = 1 μm), 64.2 parts by weight of deionized water, 4 parts by weight of polyacrylate, 1 part by weight of sodium polyacrylate, 1 part by weight of sodium carboxymethyl cellulose, and 0.2 parts by weight of fatty alcohol polyoxyethylene ether; wherein the mass ratio of acrylate-vinyl acetate-styrene copolymer to alumina was 1:1. The first slurry was coated onto the base film by gravure roller coating and dried to form a 1.5 μm first coating.

[0254] (c) Preparation of the second coating: A second slurry was prepared by using 30 parts by weight of alumina, 64.2 parts by weight of deionized water, 4 parts by weight of polyacrylate, 1 part by weight of sodium polyacrylate, 1 part by weight of sodium carboxymethyl cellulose, and 0.2 parts by weight of fatty alcohol polyoxyethylene ether. The second slurry was coated on the first coating by gravure roller coating and dried to form a 1.5 μm second coating.

[0255] (5) Assembly:

[0256] The prepared negative electrode and positive electrode are stacked in sequence, with the separator placed between the positive and negative electrode to act as a separator. The cells are then wound to obtain a bare cell, which is then inserted into the battery casing. After drying, electrolyte is injected, and the lithium-ion battery (secondary battery) is obtained through processes such as vacuum sealing, settling, formation, capacity testing, and aging.

[0257] The perovskite solar cell is prepared by the above steps (1)-(5).

[0258] The difference between Examples 2-6 and Example 1 is that the Tg temperature of the acrylate-vinyl acetate-styrene copolymer in the first coating is different, while the others are the same as in Example 1.

[0259] The difference between Examples 7-14 and Example 4 is that the weight parts of acrylate-vinyl acetate-styrene copolymer and alumina in the first coating are different, and the mass ratio of acrylate-vinyl acetate-styrene copolymer to alumina is different. Otherwise, they are the same as in Example 1.

[0260] The difference between Example 15 and Example 4 is that the weight proportion of acrylate-vinyl acetate-styrene copolymer in the first coating is different, and no first inorganic material is added; otherwise, it is the same as Example 1.

[0261] The difference between Examples 16-18 and Example 4 is that the Dv50 of the polymer material of the first coating is different, but the rest is the same as Example 1.

[0262] The difference between Examples 19-20 and Example 4 is that the polymer material of the first coating is different, but otherwise they are the same as in Example 1.

[0263] The difference between Comparative Example 1 and Example 1 is that the diaphragm does not have a first coating, but otherwise it is the same as Example 1.

[0264] The difference between Comparative Example 2 and Example 1 is that the type of polymer material and the Tg temperature of the first coating are different, while the rest are the same as in Example 1.

[0265] The relevant parameter testing process for the embodiments and comparative examples of this application is as follows:

[0266] (1) Diaphragm heat shrinkage test:

[0267] The diaphragm sample was cut into regular samples with MD×TD dimensions of 100mm×80mm, placed in a paper holder and heated. The test conditions were 130℃ for 0.5h. After two-dimensional testing, the MD×TD dimensions were amm×bmm.

[0268] MD direction shrinkage rate = (100-a) / 100×100%.

[0269] TD directional shrinkage rate = (80-b) / 80×100%.

[0270] (2) Diaphragm air permeability test:

[0271] Referencing the air permeability test method in GB / T 36363-2018, the equipment model was: Wang Yanshi air permeability tester EG01-55-1MR, the test parameters were: AVLUE parameter = 500, the measurement method was JIS sec, and the test time was 5 seconds.

[0272] (3) Cell heating box test:

[0273] The prepared battery was charged at a constant current of 0.5C to the cutoff voltage Vmax, then charged at a constant voltage until the cutoff current ≤ 0.05C, and then left to stand for 30 minutes. A temperature sensing wire was attached to the fully charged battery to monitor the cell temperature. The cell was placed in a temperature chamber, and the temperature chamber was heated from the ambient temperature to 130℃+2℃ at a rate of 5℃ / min, and this temperature was maintained for 30 minutes before heating was stopped.

[0274] Evaluation criteria: The battery passes if it does not catch fire or explode.

[0275]

[0276]

[0277]

[0278] By comparing Examples 1-21 with Comparative Example 1, the change in air permeability of the diaphragm provided in this application after baking at 130℃ / 0.5h is significantly better than that of Comparative Example 1, indicating that the polymer material in the first coating can effectively close the pores of the diaphragm after heating. Meanwhile, the pass rate of the cell hot box test using the diaphragm provided in this application is significantly better than that of Comparative Example 1, and the thermal shrinkage of the diaphragm provided in this application after baking at 130℃ / 0.5h is significantly better than that of Comparative Example 1.

[0279] By comparing Examples 7-14, the higher the proportion of polymer material in the first coating, the more obvious the change in air permeability after baking at 130℃ / 0.5h, and the more obvious the improvement effect of membrane pore closure.

[0280] It should be noted that since the test conditions were baking at 130°C, and the Tg temperature of the polymer material in Example 6 was 140°C, the test temperature was lower than the Tg temperature of the polymer material. The change in air permeability before and after baking at 130°C for 0.5h was small, and the bonding and reinforcing effect of the first coating was small, which in turn affected the shrinkage rate of the diaphragm.

[0281] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A battery cell, characterized in that, include: The housing, the battery cell assembly disposed within the housing, and the electrolyte, wherein the battery cell assembly is located in the electrolyte, and the battery cell assembly includes a positive electrode, a negative electrode, and a separator, wherein the separator is located between the positive electrode and the negative electrode; The membrane includes a base membrane and a first coating disposed on at least one side of the base membrane; the first coating includes a polymer material, the polymer material having a melting point or glass transition temperature of 90°C-140°C; and the polymer material having a median particle size of 10 nm-10 μm.

2. The battery cell according to claim 1, characterized in that, The melting point or glass transition temperature of the polymer material is 100℃-130℃.

3. The battery cell according to claim 1 or 2, characterized in that, The median particle size of the polymer material is 300 nm to 2 μm.

4. The battery cell according to any one of claims 1 to 3, characterized in that, The density of the polymer material is 0.1 g / cm³. 3 -10g / cm 3 .

5. The battery cell according to any one of claims 1 to 4, characterized in that, The density of the polymer is 0.5 g / cm³. 3 -2g / cm 3 .

6. The battery cell according to any one of claims 1 to 5, characterized in that, The polymer material includes at least one of polyacrylic acid, polymethyl methacrylate and its derivatives, polyvinylidene fluoride, acrylonitrile-butadiene-styrene copolymer, carboxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, styrene-acrylic rubber, polyacrylonitrile, polyvinyl acetal, polylactic acid, polylactic acid-glycolic acid copolymer, acrylate-vinyl acetate-styrene copolymer, and acrylate-vinyl acetate copolymer.

7. The battery cell according to any one of claims 1 to 6, characterized in that, The first coating further includes a first inorganic material; the weight ratio between the polymer material and the first inorganic material is 1-50 parts of the polymer material and 1-50 parts of the first inorganic material.

8. The battery cell according to claim 7, characterized in that, In the first coating, the mass ratio of the polymer material to the first inorganic material is 1:6-6:

1.

9. The battery cell according to claim 7 or 8, characterized in that, The median particle size of the first inorganic material is 10 nm-10 μm.

10. The battery cell according to any one of claims 7 to 9, characterized in that, The median particle size of the first inorganic material is 300 nm-2 μm.

11. The battery cell according to any one of claims 7 to 10, characterized in that, The first inorganic material includes at least one of aluminum oxide, boehmite, barium sulfate, silicon dioxide, magnesium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, zirconium oxide, and titanium dioxide.

12. The battery cell according to any one of claims 1 to 11, characterized in that, The thickness of the first coating is 0.5μm-4μm.

13. The battery cell according to any one of claims 1 to 12, characterized in that, The thickness of the first coating is 1.5μm-3μm.

14. The battery cell according to any one of claims 1 to 13, characterized in that, The diaphragm further includes a second coating, which comprises a second inorganic material; the second coating is disposed on the side of the first coating away from the base membrane, or the second coating is disposed on the side of the base membrane where the first coating is not disposed.

15. The battery cell according to claim 14, characterized in that, The median particle size of the second inorganic material is 10 nm-10 μm.

16. The battery cell according to claim 14 or 15, characterized in that, The median particle size of the second inorganic material is 300 nm-2 μm.

17. The battery cell according to any one of claims 14 to 16, characterized in that, The second inorganic material includes at least one of aluminum oxide, boehmite, barium sulfate, silicon dioxide, magnesium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, zirconium oxide, and titanium dioxide.

18. The battery cell according to any one of claims 14 to 17, characterized in that, The thickness of the second coating is 0.5μm-4μm.

19. The battery cell according to any one of claims 14 to 18, characterized in that, The thickness of the second coating is 1.5μm-3μm.

20. The battery cell according to any one of claims 1 to 19, characterized in that, The thickness of the base film is 1μm-30μm.

21. The battery cell according to any one of claims 1 to 20, characterized in that, The porosity of the base membrane is 10%-80%.

22. The battery cell according to any one of claims 1 to 21, characterized in that, The base film includes at least one of polyethylene film, polypropylene film, polyethylene-polypropylene composite film, polyimide film, and polyester film.

23. A method for preparing a single battery cell, characterized in that, include: A battery cell assembly is formed by sequentially stacking negative electrode plates, a separator, and positive electrode plates; The battery cell assembly is placed inside the housing; as well as Electrolyte is injected into the casing and sealed to form a battery cell; The method for preparing the diaphragm includes: Provide base film; A first slurry is coated on at least one side of a base film to form a first coating; the first slurry comprises a polymer material having a melting point or glass transition temperature of 90°C-140°C; and the median particle size of the polymer material is 10 nm-10 μm.

24. The method for preparing a single battery cell according to claim 23, characterized in that, The first slurry further includes a first inorganic material, a first binder, a first dispersant, a first wetting agent, and a first solvent. The weight ratio of the polymer material, the first inorganic material, the first binder, the first dispersant, the first wetting agent, and the first solvent is as follows: 1 part to 50 parts of the polymer material, 1 part to 50 parts of the first inorganic material, 1 part to 10 parts of the first binder, 0.1 part to 2 parts of the first dispersant, 0.01 part to 1 part of the first wetting agent, and 1 part to 80 parts of the first solvent.

25. The method for preparing a single battery cell according to claim 24, characterized in that, The method for preparing the diaphragm further includes: A second slurry is applied to the side of the first coating away from the base film or to the side of the base film where the first coating is not applied, to form a second coating; The second slurry comprises a second inorganic material, a second binder, a second dispersant, a second wetting agent, and a second solvent; the weight ratio of the second inorganic material, the second binder, the second dispersant, the second wetting agent, and the second solvent is as follows: 1 part to 80 parts of the second inorganic material, 1 part to 10 parts of the second binder, 0.1 part to 2 parts of the second dispersant, 0.01 part to 1 part of the second wetting agent, and 1 part to 80 parts of the second solvent.

26. The method for preparing a single battery cell according to claim 25, characterized in that, The polymer material includes at least one of polyacrylic acid, polymethyl methacrylate and its derivatives, polyvinylidene fluoride, acrylonitrile-butadiene-styrene copolymer, carboxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, styrene-acrylic rubber, polyacrylonitrile, polyvinyl acetal, polylactic acid, polylactic-glycolic acid copolymer, and acrylate-vinyl acetate-styrene copolymer; and / or, The first inorganic material and the second inorganic material each independently include at least one of aluminum oxide, boehmite, barium sulfate, silicon dioxide, magnesium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, zirconium oxide, and titanium dioxide; and / or, The first adhesive and the second adhesive each independently include at least one of polyacrylic acid, polyacrylate, styrene-butadiene rubber, styrene-acrylic emulsion, polyurethane, and polyacrylonitrile; and / or, The first dispersant and the second dispersant each independently comprise at least one of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, sodium polyacrylate, and polyacrylamide; and / or, The first wetting agent and the second wetting agent each independently comprise at least one of alkyl alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, polyoxyethylene ether, alkylbenzene sulfonate, and alkyl sulfate; and / or, The first solvent and the second solvent each independently include water.

27. A diaphragm, characterized in that, The material includes a base film and a first coating disposed on at least one side of the base film; the first coating includes a polymer material having a melting point or glass transition temperature of 90°C-140°C; and the polymer material having a median particle size of 10 nm-10 μm.

28. A battery device, characterized in that, This includes battery cells as described in any one of claims 1 to 22, or battery cells prepared by any one of claims 23 to 26.

29. An electrical appliance, characterized in that, This includes the battery device as described in claim 28, or the battery cell as described in any one of claims 1 to 22, or the battery cell prepared by the method described in any one of claims 23 to 26.

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