Diaphragm, preparation method thereof, battery, energy storage device and electric equipment

Abstract

The application provides a diaphragm and a preparation method thereof, a battery, an energy storage device and an electric equipment, wherein the diaphragm comprises a substrate layer and a glue layer arranged on at least one side surface of the substrate layer, and the glue layer comprises glue point particles; the diaphragm satisfies the relationship: 2≤Q / (S*100F)≤40; wherein S represents the single surface density of the glue layer, and the unit is g / m 2 ; F represents the coverage of the glue point particles on the surface of the substrate layer; and Q represents the average peeling strength between the diaphragm and a positive electrode sheet, and the unit is N / m.

Description

Technical Field

[0001] This application relates to the field of electrochemical technology, and in particular to a separator and its preparation method, a battery, an energy storage device, and an electrical device. Background Technology

[0002] Secondary batteries (such as lithium-ion batteries) typically consist of a positive electrode, a separator, a negative electrode, and an electrolyte. The separator is located between the positive and negative electrodes and serves to separate the positive and negative electrodes, preventing them from coming into contact and short-circuiting.

[0003] PCS (Polymer Coating Separator) is a type of separator with a polymer coating added to the surface of the separator substrate. Currently, when the areal density of the polymer coating is low (e.g., areal density not exceeding 0.1 g / m³), it is suitable for applications where the areal density is low. 2 This can easily lead to poor adhesion between the separator and the electrode plates. In particular, after the bare cells are pressed at room temperature and left to stand for a period of time, they are prone to loosening and opening, making it difficult to fit into the casing, and even affecting the battery's interface and rate performance. Summary of the Invention

[0004] To address the aforementioned technical problems, this application discloses a separator and its preparation method, a battery, an energy storage device, and an electrical device, which enables the polymer layer of the separator to maintain good adhesion performance even at a low areal density.

[0005] In a first aspect, this application provides a diaphragm, including a substrate layer and an adhesive layer disposed on at least one surface of the substrate layer, the adhesive layer including adhesive dots; The diaphragm satisfies the following relationship: 2≤Q / (S×100F)≤40; Wherein, S represents the surface density of the adhesive layer on one side, in g / m³. 2 ; F represents the coverage of the adhesive particles on the surface of the substrate layer; Q represents the average peel strength between the separator and the positive electrode, expressed in N / m.

[0006] In some embodiments of this application, the diaphragm satisfies the relationship: 5≤Q / (S×100F)≤25.

[0007] In some embodiments of this application, the diaphragm satisfies at least one of the following characteristics: a) 0.05 ≤ S ≤ 0.25; b) 1% ≤ F ≤ 10%; c) 1 ≤ Q ≤ 5.

[0008] In some embodiments of this application, the average particle size Dv50 of the adhesive dots is 0.2 μm to 3 μm.

[0009] In some embodiments of this application, the adhesive particles contain a polymer, the polymer comprising at least one of polymethyl methacrylate, polyacrylate, polystyrene, and polyvinylidene fluoride modified with supercritical or liquid carbon dioxide.

[0010] Secondly, this application provides a method for preparing a diaphragm as described in the first aspect, comprising the following steps: An initial adhesive layer slurry is prepared, and the solid content of the initial adhesive layer slurry is adjusted to 10%~30%, wherein the solvent of the initial adhesive layer slurry includes water; The initial adhesive slurry is mixed with supercritical carbon dioxide or liquid carbon dioxide to obtain a mixed adhesive slurry. The polymer particles in the mixed adhesive slurry swell under the action of the supercritical carbon dioxide or liquid carbon dioxide. The mass percentage of the supercritical carbon dioxide or liquid carbon dioxide in the mixed adhesive slurry is 1 wt% to 30 wt%, based on the mass of the solvent in the mixed adhesive slurry. The mixed adhesive slurry is sprayed onto the surface of the substrate layer of the diaphragm. Under the action of gas explosion atomization and pressure atomization of supercritical carbon dioxide or liquid carbon dioxide, the mixed adhesive slurry is dispersed on the surface of the substrate layer and forms adhesive particles.

[0011] In some embodiments of this application, the viscosity of the mixed adhesive slurry is 5 mPa·s to 200 mPa·s.

[0012] In some embodiments of this application, the temperature of the supercritical carbon dioxide or the liquid carbon dioxide before mixing is 25°C to 50°C, and the pressure is 7.4 MPa to 25 MPa.

[0013] Thirdly, this application provides a battery comprising the separator described in the first aspect, or a separator prepared by the method described in the second aspect.

[0014] Fourthly, this application provides an energy storage device, including a housing and at least one battery as described in the third aspect, the battery being housed within the housing.

[0015] Fifthly, this application provides an electrical device including the energy storage device described in the fourth aspect, wherein the energy storage device supplies power to the electrical device.

[0016] Compared with the prior art, this application has at least the following beneficial effects: This application provides a separator, its preparation method, a battery, an energy storage device, and an electrical device. The separator includes a substrate layer and an adhesive layer disposed on at least one surface of the substrate layer. The adhesive layer includes adhesive particles. The separator satisfies the following relationship: 2 ≤ Q / (S×100F) ≤ 40, where S represents the areal density of the adhesive layer on one side, in g / m³. 2 F represents the coverage of adhesive particles on the substrate layer surface; Q represents the average peel strength between the separator and the positive electrode, in N / m. By adjusting S, F, and Q to satisfy the above relationship, the separator maintains high peel strength while having a lower areal density in the adhesive layer, exhibiting good adhesion performance. Simultaneously, the adhesive particles are more uniformly distributed on the separator surface, resulting in good thickness uniformity. Batteries with the separator of this application are less prone to wrinkling at the electrode interface, while still maintaining good energy efficiency. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a scanning electron microscope image of the diaphragm surface obtained in Example 1 of this application; Figure 2 This is a schematic diagram of the structure of an energy storage system according to one embodiment of this application; Figure 3 This is a schematic diagram of the energy storage system according to another embodiment of this application; Figure 4 This is a schematic diagram of the energy storage system according to another embodiment of this application; Figure 5 The image shows a scanning electron microscope (SEM) image of the surface particles of the diaphragm prepared in Comparative Example 1.

[0019] Explanation of reference numerals in the attached drawings: 400-Energy storage system, 410-First power conversion device, 420-First user load, 430-Second user load, 440-Energy storage device, 450-High voltage cable, 460-Second power conversion device, 470-Vehicle, 480-Photovoltaic-energy storage-charging station. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. 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.

[0021] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0022] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0023] It should be noted that this application uses lithium-ion batteries as an example of secondary batteries to explain the application, but the secondary batteries in this application are not limited to lithium-ion batteries.

[0024] This application provides a separator comprising a substrate layer and an adhesive layer disposed on at least one surface of the substrate layer. In one embodiment, the adhesive layer is disposed on the surface of the substrate layer facing the positive electrode; in another embodiment, the adhesive layer is disposed on the surface of the substrate layer facing the negative electrode; in yet another embodiment, the adhesive layer is disposed on both sides of the substrate layer, and the two sides of the substrate layer face the positive electrode and the negative electrode, respectively.

[0025] like Figure 1 As shown, the adhesive layer includes adhesive particles that are dispersed on the surface of the substrate layer. These particles can be nearly spherical and contain a polymer that provides adhesion to the adhesive layer. The diaphragm satisfies the following relationship: 2 ≤ Q / (S×100F) ≤ 40; in another embodiment, 5 ≤ Q / (S×100F) ≤ 25. Where S represents the areal density of the adhesive layer on one side, in g / m³. 2F represents the coverage of adhesive particles on the substrate surface; Q represents the average peel strength between the separator and the positive electrode, in N / m. For example, Q / (S×100F) can be 2, 5, 10, 15, 20, 25, 30, 35, or 40. In the formula Q / (S×100F), S reflects the amount of adhesive coating in the separator, F reflects the coverage of adhesive particles in the separator, and Q reflects the adhesion of the separator. When S is too large, it indicates a large amount of adhesive coating, large fluctuations in the thickness of the adhesive layer, and the energy efficiency may be affected; when S is too small, it indicates a small amount of adhesive coating, the adhesion between the separator and the electrode may be weak, and the bare cell is prone to loosening and opening after pressing; when F is too large, it indicates a large coverage area of ​​adhesive particles on the separator surface, a large ion impedance of the battery, and the uniformity of the separator thickness is easily affected; when F is too small, it indicates a small coverage area of ​​adhesive particles on the separator surface, and the adhesion of the separator will be affected. Based on this, this application achieves the desired relationship by adjusting S, F, and Q. The adhesive layer of the separator exhibits low areal density while maintaining high peel strength, demonstrating excellent adhesion. Furthermore, the adhesive particles are more evenly distributed on the separator surface, resulting in good thickness uniformity. Batteries with the separator of this application are less prone to wrinkling at the electrode interface, and the lithium-ion battery still maintains good energy efficiency.

[0026] In one alternative embodiment, the diaphragm satisfies at least one of the following characteristics: 0.05 ≤ S ≤ 0.25; 1% ≤ F ≤ 10%; 1 ≤ Q ≤ 5. For example, S is 0.05, 0.1, 0.15, 0.2, or 0.25; F is 1%, 2%, 5%, 7%, or 10%; and Q is 1, 2, 3, 4, or 5. With S, F, and Q within the above ranges, while satisfying the relationships of this application, it is advantageous for the diaphragm to maintain high peel strength and good thickness uniformity while having a lower areal density in the adhesive layer.

[0027] In one optional embodiment, the adhesive particles contain a polymer, including at least one of polymethyl methacrylate (PMMA), polyacrylate (PAA), polystyrene (PS), and polyvinylidene fluoride (PVDF) modified with supercritical or liquid carbon dioxide, preferably PMMA modified with supercritical or liquid carbon dioxide. The polymer modified with supercritical or liquid carbon dioxide can produce stronger adhesion and ionic conductivity to the positive electrode sheet, thereby improving the membrane adhesion performance while reducing ionic resistance.

[0028] In one optional embodiment, the average particle size Dv50 of the adhesive dots is 0.2 μm to 3 μm. For example, Dv50 is 0.2 μm, 0.5 μm, 0.8 μm, 1 μm, 2 μm, 2.5 μm, or 3 μm. The aforementioned smaller particle size is beneficial for reducing thickness fluctuations after adhesive layer formation, and the smaller particle size adhesive dots are more likely to swell under the action of supercritical carbon dioxide or liquid carbon dioxide.

[0029] In this application, Dv50 represents the particle size that, in the volumetric particle size distribution, reaches 50% of the total volumetric size, starting from the smallest particle size.

[0030] In this application, the average thickness of the adhesive layer can be from 0.2 μm to 3 μm. For example, the average thickness of the adhesive layer can be 0.2 μm, 0.5 μm, 1 μm, 2 μm, or 3 μm. The remaining components of the adhesive layer may include, but are not limited to, other binders, dispersants, and surfactants. These remaining components can be adjusted by those skilled in the art according to actual process requirements, and this application does not impose any particular restrictions.

[0031] This application also provides a method for preparing a diaphragm, comprising the following steps: Step A: Prepare the initial adhesive layer slurry and adjust the solid content of the initial adhesive layer slurry to 10%~30%. The solvent of the initial adhesive layer slurry includes water. Step B: Mix the initial adhesive slurry with supercritical carbon dioxide or liquid carbon dioxide to obtain a mixed adhesive slurry. The polymer particles in the mixed adhesive slurry swell under the action of supercritical carbon dioxide or liquid carbon dioxide. The mass percentage of supercritical carbon dioxide or liquid carbon dioxide in the mixed adhesive slurry is 1 wt% to 30 wt%, based on the mass of the solvent. Step C: Spray the mixed adhesive slurry onto the surface of the substrate layer of the diaphragm. Under the action of supercritical carbon dioxide or liquid carbon dioxide gas explosion atomization and pressure atomization, the mixed adhesive slurry is dispersed on the surface of the substrate layer and forms adhesive particles.

[0032] In step A, the raw materials used to prepare the initial adhesive layer slurry can be mixed and a solvent added, and the raw materials are mixed evenly by continuous stirring. The raw materials include, but are not limited to, polymer particles, other binders (such as styrene-butadiene rubber (SBR), dispersants, and surfactants. The solvent for the initial adhesive layer slurry in this application includes water, preferably deionized water. Dispersants include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, polyethylene glycol, and polyether polyols, and surfactants include, but are not limited to, polyvinyl alcohol, sodium dodecylbenzene sulfonate, and triethylenediamine.

[0033] In step B, a mixer can be used to uniformly mix the initial adhesive slurry obtained in step A with supercritical carbon dioxide or liquid carbon dioxide to obtain a mixed adhesive slurry, i.e., an adhesive slurry mixed with carbon dioxide. If the amount of supercritical carbon dioxide or liquid carbon dioxide added is too high, the excess carbon dioxide will extract the binder (such as acrylate) dissolved in deionized water in the adhesive slurry, leading to the precipitation of water-soluble binder. In addition, the excess carbon dioxide will form a two-phase separation with the adhesive slurry, which will seriously affect the spraying of the slurry. If the amount of supercritical carbon dioxide or liquid carbon dioxide added is too low, it will be difficult for the solvent to expand in volume, making it difficult to form a low-viscosity, stable mixed slurry system. Based on this, by controlling the solvent-based mass percentage of supercritical carbon dioxide or liquid carbon dioxide in the mixed adhesive slurry within the scope of this application, supercritical carbon dioxide or liquid carbon dioxide is dissolved in a solvent (e.g., water). Through the disruption of the hydrogen bond network of water by supercritical carbon dioxide or liquid carbon dioxide, the insertion effect of CO2 molecules, and the introduction of low-viscosity, highly diffusive fluid components, the volume of water expands, significantly reducing the viscosity of the mixed adhesive slurry. This enables rapid spraying and deposition of high-solids-content PCS adhesive slurry onto the substrate layer, allowing the coating speed of the PCS adhesive slurry to be compatible with the winding speed of the bare battery cell, and achieving rapid drying after adhesion, thus improving the production efficiency of separator coating; it also avoids additional baking time, further reducing baking energy consumption. It is evident that keeping the temperature and pressure of the supercritical carbon dioxide or liquid carbon dioxide within the aforementioned range before mixing can reduce the viscosity of the mixed adhesive slurry while ensuring the quality of the slurry. In this application, the pressure, temperature, and metering delivery of CO2 can be controlled by a booster pump, a constant temperature bath, and a pressure stabilization metering system. In addition, this application can also control the pH value of the slurry system within the range of 6 to 7 by online pH detection.

[0034] On the other hand, supercritical carbon dioxide or liquid carbon dioxide also has a certain swelling effect on polymer particles. Taking PMMA as an example, when polymer particles in the initial adhesive slurry are treated with supercritical or liquid carbon dioxide under high pressure, the high permeability of supercritical or liquid carbon dioxide allows CO2 to penetrate into the gaps between PMMA molecular chains, causing a slight expansion in volume, i.e., partial swelling; and weakening the intermolecular forces, the glass transition temperature decreases accordingly, which is one of the factors that enable the prepared adhesive layer to have high bonding strength under room temperature pressing conditions; furthermore, during the decompression process, as CO2 evaporates, the PMMA surface swells and its easily softened properties are solidified. This property makes PMMA easy to gel and adsorb in the electrolyte, forming a PMMA gel electrolyte-like effect, thereby producing a strong bonding effect and ionic conductivity on the positive electrode, which can improve the membrane bonding performance while reducing ionic impedance.

[0035] The mixers in this application include static mixers, orifice plates, venturi tubes, etc., which can achieve good dispersion and thorough mixing between different fluids, and their permeation and dispersion effects are better than stirring.

[0036] In step C, a spray gun can be used to spray the mixed adhesive slurry onto at least a portion of the surface of the substrate layer, followed by drying, thus obtaining a diaphragm mixed adhesive slurry with an adhesive layer. After being delivered to the spray gun, the slurry undergoes gas explosion atomization and pressure atomization. Specifically, gas explosion atomization is the primary effect, causing a sharp drop in outlet pressure when the mixed adhesive slurry is sprayed out, resulting in the rapid expansion and vaporization of most of the CO2, which breaks the surrounding liquid film into fine liquid mist particles. Pressure atomization is secondary, with the jet and air shearing action breaking up the mixed adhesive slurry droplets, thereby uniformly and dispersedly spraying the mixed adhesive layer onto the substrate layer. After drying, a PCS diaphragm coating, i.e., the adhesive layer, is formed. In this application, the spray gun shape can be circular, rounded rectangular, V-shaped, etc.

[0037] In one optional embodiment, the viscosity of the mixed adhesive slurry is 5 mPa·s to 200 mPa·s, which has a low viscosity and is conducive to the rapid spraying and deposition of high solids content PCS adhesive slurry onto the substrate layer.

[0038] In one optional embodiment, the temperature of the supercritical carbon dioxide or liquid carbon dioxide before mixing is 25°C to 50°C, preferably 31.5°C to 36°C; and the pressure is 7.4 MPa to 25 MPa, preferably 10 MPa to 15 MPa. Within these temperature and pressure ranges, it is beneficial for an appropriate amount of CO2 to dissolve in the solvent, thereby causing the solvent to expand in volume and reducing the viscosity of the mixed adhesive slurry.

[0039] This application provides a method for preparing a diaphragm that can effectively increase the solid content of the adhesive slurry while maintaining a low viscosity. The increased solid content further shortens drying time and oven length, thereby improving production efficiency and reducing space requirements. Furthermore, this preparation method does not require the introduction of any toxic or harmful solvents or gases, making it environmentally friendly. Additionally, this method allows for an increased coating width; for example, one spray gun can correspond to one coating line, or multiple spray guns can be used simultaneously to correspond to one coating line, thereby improving production efficiency.

[0040] This application also provides a battery comprising the separator described in any of the above embodiments, or a separator prepared by the method described in any of the above embodiments.

[0041] This application does not impose any particular restrictions on the substrate layer of the diaphragm; those skilled in the art can choose according to actual needs, as long as the purpose of this application can be achieved. For example, the substrate layer can be a nonwoven fabric, membrane, or composite membrane with a porous structure, and the material of the substrate layer can be selected from at least one of polyethylene, polypropylene, polyethylene terephthalate, and polyimide. Specifically, a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite membrane can be selected.

[0042] The lithium-ion battery of this application also includes a positive electrode sheet. This application does not impose any particular limitation on the positive electrode sheet, as long as it achieves the purpose of this application. For example, the positive electrode sheet typically includes a positive current collector and a positive electrode material layer. The positive electrode material layer can be disposed on one surface or on two surfaces along the thickness direction of the positive current collector. In this application, the positive electrode material layer is disposed on the surface of the positive current collector; that is, the positive electrode material layer can be disposed on a portion of one surface of the positive current collector or on the entire surface of one surface of the positive current collector. In this application, there is no particular limitation on the positive current collector, as long as it achieves the purpose of this application. For example, it can include, but is not limited to, aluminum foil, aluminum alloy foil, or composite current collectors. In this application, there is no particular limitation on the thickness of the positive current collector, as long as it achieves the purpose of this application. For example, a thickness of 4μm to 15μm is acceptable. The single-sided thickness of the positive electrode material layer in this application can be 50μm to 150μm.

[0043] The lithium-ion battery of this application also includes a negative electrode sheet. This application does not impose any particular limitation on the negative electrode sheet, as long as it achieves the purpose of this application. For example, the negative electrode sheet typically includes a negative current collector and a negative electrode material layer. The negative electrode material layer can be disposed on one or both surfaces along the thickness direction of the negative current collector. In this application, the negative electrode material layer is disposed on the surface of the negative current collector; that is, the negative electrode material layer can be disposed on a portion of one surface of the negative current collector, or it can be disposed on the entire surface of one surface of the negative current collector. This application does not impose any particular limitation on the negative current collector, as long as it achieves the purpose of this application. For example, it can include, but is not limited to, copper foil, copper alloy foil, nickel foil, or composite current collectors. In this application, there is no particular limitation on the thickness of the negative current collector, as long as it achieves the purpose of this application, for example, a thickness of 4μm to 12μm. The single-sided thickness of the negative electrode material layer in this application can be 50μm to 120μm.

[0044] In this application, the negative electrode material layer includes a negative electrode material. The negative electrode material is not particularly limited, as long as it can achieve the purpose of this application. For example, it may include at least one of artificial graphite, natural graphite, mesophase carbon microspheres, soft carbon, hard carbon, silicon, and silicon-carbon.

[0045] In this application, the negative electrode material layer may also include a negative electrode binder. This application does not impose any particular limitation on the negative electrode binder, as long as it can achieve the purpose of this application. For example, it may include, but is not limited to, at least one of acrylate, polyamide, polyimide, polyamide-imide, polyvinylidene fluoride, styrene-butadiene rubber, sodium alginate, polyvinyl alcohol, polytetrafluoroethylene, polyacrylonitrile, sodium carboxymethyl cellulose, and potassium carboxymethyl cellulose.

[0046] The battery of this application also includes an electrolyte. This application does not impose any particular limitations on the electrolyte; those skilled in the art can choose according to actual needs, as long as it achieves the purpose of this application. For example, at least one of ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl propionate (EP), propyl propionate (PP), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), vinylene carbonate (VC), ethylene ethylene carbonate (VEC), or fluoroethylene carbonate (FEC) can be mixed in a certain mass or volume ratio to obtain a non-aqueous organic solvent, and then a lithium salt can be added to dissolve and mix evenly. This application does not limit the type of lithium salt, as long as it achieves the purpose of this application. For example, lithium salts may include at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, LiSiF6, lithium bis(fluorosulfonyl)imide (LIFSI), lithium dioxalatoborate (LiBOB), or lithium difluoroborate.

[0047] This application does not impose any particular limitation on the concentration of lithium salt in the electrolyte, as long as the purpose of this application can be achieved. For example, the concentration of lithium salt can be 1.0 mol / L to 2.0 mol / L.

[0048] The battery of this application also includes a casing. This application does not impose any particular restrictions on the casing, and those skilled in the art can choose one according to actual needs, as long as it can achieve the purpose of this application. For example, the casing may include an aluminum-plastic film.

[0049] This application does not impose any particular limitation on the battery preparation method; any preparation method known in the art can be used, as long as it can achieve the purpose of this application. For example, the battery preparation method includes, but is not limited to, the following steps: stacking the positive electrode, separator, and negative electrode in sequence, and performing operations such as winding and folding as needed to obtain a bare cell with a wound structure; placing the bare cell in a packaging bag; injecting electrolyte into the packaging bag and sealing it to obtain the battery.

[0050] This application also provides an energy storage device, including a housing and at least one battery as described in any of the above embodiments, the battery being housed within the housing. The energy storage device with this battery exhibits excellent performance, which is beneficial for its use. Housing the battery within the housing increases its stability and protection, thereby extending the lifespan of the energy storage device. It is understood that the energy storage device may contain one or more batteries, and when the energy storage device contains multiple batteries, the multiple batteries can be connected in at least one manner, such as parallel or series connection.

[0051] This application also provides an electrical device including the energy storage device described in the above embodiments, which is beneficial for improving the product competitiveness and performance of the electrical device. In an optional embodiment, the electrical device includes an electrical device body, and the energy storage device is used to supply power to the electrical device body. In an optional embodiment, the electrical device body includes a positive terminal and a negative terminal, the positive electrode of the battery in the energy storage device is used to electrically connect to the positive terminal of the electrical device body, and the negative electrode of the battery in the energy storage device is used to electrically connect to the negative terminal of the electrical device body, so as to supply power to the electrical device.

[0052] The electrical equipment in this application may include, but is not limited to: containers, electric vehicles, electric cars, ships, spacecraft, electric toys, and power tools, etc. Among them, spacecraft include, for example, airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include, for example, stationary or mobile electric toys, specifically, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include, for example, metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, specifically, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers.

[0053] Because the energy we need is highly time- and space-dependent, in order to utilize energy rationally and improve energy efficiency, it is necessary to store one form of energy in the same way or by converting it into another, and then release it in a specific energy form for future applications. Currently, the main way to generate green electricity is to develop green energy sources such as photovoltaics and wind power to replace fossil fuels. Currently, the generation of green electricity generally relies on solar, wind, and hydropower. However, wind and solar power are generally characterized by strong intermittency and large fluctuations, which can cause grid instability, insufficient power during peak demand periods, and excessive power during off-peak periods. Unstable voltage can also damage the power grid. Therefore, insufficient electricity demand or insufficient grid capacity may lead to the problem of "wind and solar curtailment." Solving these problems requires energy storage. This involves converting electrical energy into other forms of energy through physical or chemical means and storing it. When needed, this energy can be converted back into electrical energy and released. Simply put, energy storage is like a large "power bank," storing electrical energy when solar and wind power are abundant and releasing the stored electricity when needed.

[0054] Taking electrochemical energy storage as an example, this solution provides an energy storage device 440, which is applied to an energy storage system 400. The energy storage device 440 is equipped with a set of chemical batteries, which mainly use the chemical elements in the batteries as energy storage medium. The charging and discharging process is accompanied by the chemical reaction or change of the energy storage medium. Simply put, the electrical energy generated by wind and solar energy is stored in the chemical batteries. When the use of external electrical energy reaches its peak, the stored electrical energy is released for use, or transferred to places with a shortage of electricity for use.

[0055] Current energy storage applications are quite widespread, including generation-side energy storage, grid-side energy storage, and consumption-side energy storage. The corresponding types of energy storage devices include: (1) Large-scale energy storage power stations (composed of multiple prefabricated energy storage modules) applied to wind power and photovoltaic power stations can help renewable energy power generation meet grid connection requirements and improve the utilization rate of renewable energy. As a high-quality active / reactive power regulation power source on the power supply side, the energy storage power station realizes the load matching of power in time and space, enhances the renewable energy absorption capacity, reduces instantaneous power changes, reduces the impact on the power grid, improves the problem of new energy power generation absorption, and is of great significance in power grid system backup, alleviating peak load power supply pressure and peak regulation and frequency regulation. (2) The energy storage prefabricated cabin applied on the grid side mainly functions as peak regulation, frequency regulation and grid congestion relief. In terms of peak regulation, it can realize peak shaving and valley filling of electricity load, that is, charging the energy storage battery when the electricity load is low and releasing the stored electricity during the peak electricity load period, thereby achieving a balance between power production and consumption. (3) Small energy storage cabinets applied to the electricity consumption side mainly function as self-consumption of electricity, peak-valley price arbitrage, capacity cost management, and improvement of power supply reliability. Depending on the application scenario, electricity consumption side energy storage can be divided into industrial and commercial energy storage cabinets, household energy storage devices, energy storage charging piles, etc., which are generally used in conjunction with distributed photovoltaics. Industrial and commercial users can use energy storage for peak-valley price arbitrage and capacity cost management. In the electricity market implementing peak-valley pricing, by charging the energy storage system when the electricity price is low and discharging the energy storage system when the electricity price is high, peak-valley price arbitrage can be achieved, reducing electricity costs. In addition, industrial enterprises subject to two-part tariffs can use energy storage systems to store energy during off-peak hours and discharge during peak loads, thereby reducing peak power and the maximum demand declared, achieving the goal of reducing capacity costs. Household photovoltaics with energy storage can improve the level of self-consumption of electricity. Due to high electricity prices and poor power supply stability, the demand for household photovoltaic installations is driven. Given that photovoltaic power generation occurs during the day, while user load is generally higher at night, configuring energy storage can better utilize photovoltaic power, improve self-consumption levels, and reduce electricity costs. Furthermore, energy storage is needed in areas such as communication base stations and data centers for backup power.

[0056] In some embodiments, see Figure 2 , Figure 2 This is a schematic diagram of the structure of an energy storage system 400 according to an embodiment of this application. Figure 1 This application Figure 2 The embodiments are illustrated using a home energy storage scenario in user-side energy storage as an example. The energy storage device 440 of this application is not limited to the home energy storage scenario.

[0057] This application provides an energy storage system 400, which includes a first power conversion device 410 (photovoltaic panel), a first user load 420 (household lighting fixture), a second user load 430 (e.g., household appliances such as air conditioners), and an energy storage device 440. The energy storage device 440 is a small energy storage box that can be wall-mounted on an outdoor wall. However, the energy storage device 440 is not limited to wall mounting and can also be placed in a user's residence in other ways. Specifically, the photovoltaic panel can convert solar energy into electrical energy during periods of low electricity prices, and the energy storage device 440 stores this electrical energy and supplies it to lighting fixtures and household appliances during peak electricity prices, or provides power during power outages / power interruptions.

[0058] In some embodiments, see Figure 3 , Figure 3 This is a schematic diagram of the structure of an energy storage system 400 according to an embodiment of this application. Figure 1 And this application Figure 3 The embodiments are illustrated using a shared energy storage scenario on the generation / distribution side as an example. The energy storage device 440 of this application is not limited to the energy storage scenario on the generation / distribution side.

[0059] This application provides an energy storage system 400, which includes: a high-voltage cable 450, a first power conversion device 410, a second power conversion device 460, and an energy storage device 440 provided in this application. In some embodiments of the power generation scenario, the second power conversion device 460 can be a wind power conversion device. Since the electricity generated by wind power conversion is volatile, random, and intermittent, the unstable electricity output by the wind power conversion device can be stored in the energy storage device 440 through grid connection. The energy storage device 440 is connected to the high-voltage cable and outputs smooth electricity to the power consumption side of the distribution network, realizing peak shaving and frequency regulation, and stable grid operation; or, wind power... The conversion device is always connected to the high-voltage cable. Under normal power generation conditions, the power output of the wind power conversion device is supplied to the power consumption side of the distribution network through the high-voltage cable. When the current power load is low and the wind power conversion device generates excess power, the excess power is first stored in the energy storage device 440 to reduce wind and solar curtailment rates and improve the problem of new energy power generation consumption. When the power load is high, the power grid issues an instruction to transmit the power stored in the energy storage device 440 together with the high-voltage cable 450 in grid-connected mode to supply power to the power consumption side. This provides the power grid with various services such as peak shaving, frequency regulation, and backup, giving full play to the peak shaving role of the power grid, promoting peak shaving and valley filling, and alleviating the power supply pressure of the power grid.

[0060] In some embodiments on the distribution network side, the first power conversion device 410 can be a photovoltaic panel, and the energy storage device 440 is connected to the high-voltage cable 450 and installed downstream of the high-voltage cable 450 and between the user load. The electrical energy output by the photovoltaic power conversion device is stored in the energy storage device 440, which can respond in a timely manner to act as a backup power source when the power grid / distribution network fails; or, it can provide power supply support to alleviate line congestion when the high-voltage cable 450 transmission line is blocked, and to delay the economic pressure caused by the expansion of the power grid / distribution capacity when the power grid is planned to be expanded.

[0061] In some embodiments, see Figure 4 , Figure 4 This is a schematic diagram of the structure of an energy storage system 400 according to an embodiment of this application. Figure 3 And this application Figure 4 The embodiments are illustrated using an industrial and commercial energy storage scenario as an example. The energy storage device 440 of this application is not limited to industrial and commercial energy storage scenarios.

[0062] This application provides an energy storage system 400, which includes: an energy storage device 440, a high-voltage cable 450, a factory equipped with a first power conversion device 410, a photovoltaic-energy storage-charging station 480, and a vehicle 470. In some embodiments of industrial and commercial scenarios, the first power conversion device 410 can be a photovoltaic panel, which converts solar energy into electrical energy and stores it in the energy storage device 440 in the factory. In the event of a power grid failure, the energy storage device 440 provides power to ensure the safe and stable operation of the factory without interruption. Alternatively, when the factory's power load is high, the power grid issues an instruction to transmit the electricity stored in the energy storage device 440 in conjunction with the high-voltage cable 450 in a grid-connected mode to supply the factory with electricity, providing various services such as peak shaving / frequency regulation and backup for the power grid operation. In addition, the first power conversion device 410 can also convert solar energy into electrical energy and store it in the energy storage device 440 of the photovoltaic-energy storage-charging station 480, which can then directly charge the vehicle 470, making it fast and convenient.

[0063] Optionally, the first power conversion device 410 may include, but is not limited to, a photovoltaic panel, and the second power conversion device 460 may include, but is not limited to, a wind power conversion device. The first power conversion device 410 and the second power conversion device 460 can convert at least one of solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy, and mechanical energy into electrical energy.

[0064] Optionally, the energy storage device 440 may include, but is not limited to, energy storage applications such as energy storage power stations, hydropower / thermal / wind power generation systems, solar power generation systems, mobile power systems, smart home systems, or temporary power supply systems, and may also be applied in multiple fields such as data centers, military equipment, aerospace, charging piles, and electric vehicles.

[0065] Optionally, the energy storage device 440 may include, but is not limited to, individual batteries, or battery modules, battery packs, battery clusters, power banks, energy storage cabinets / prefabricated energy storage compartments, and other battery integrated systems composed of individual batteries. The actual application form of the energy storage device 440 provided in this application embodiment may be, but is not limited to, the listed products, and may also be other application forms. This application embodiment does not strictly limit the application form of the energy storage device 440.

[0066] Optionally, the individual cell can be, but is not limited to, at least one of cylindrical, prismatic, prismatic, or other shaped cells.

[0067] Optionally, the single cell can be a rechargeable battery, which refers to a single cell that can be recharged after discharge to activate the active materials and continue to be used. The single cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and this application does not specifically limit it.

[0068] Example The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below.

[0069] Example 1 <Preparation of the diaphragm> PMMA, SBR, methyl acrylate emulsion, and polyvinyl alcohol were weighed according to a mass ratio of 72:2:25:1. First, deionized water was added to a mixer as a solvent, followed by the weighed polyvinyl alcohol. The mixture was stirred at 1000 rpm for 15 minutes until homogeneous. Then, SBR was added, and the mixture was stirred at 1000 rpm for 15 minutes until homogeneous, maintaining the system temperature at approximately 40°C and the pH at approximately 7. Next, PMMA was added, and the mixture was stirred at 2500 rpm for 90 minutes until homogeneous. Then, methyl acrylate emulsion was added, and the mixture was stirred at 1500 rpm for 30 minutes until homogeneous. Finally, the mixture was slowly stirred at 500 rpm for 15 minutes to eliminate air bubbles, and the solid content of the initial adhesive layer slurry was adjusted to 25 wt%. The initial adhesive layer slurry was then transported via a screw pump, and supercritical carbon dioxide was introduced into the screw pump pipeline to combine with the initial adhesive layer slurry. The mixture was then transported to a static mixer for further mixing and dispersion. The pH was monitored online and controlled at 6-7 to obtain the mixed adhesive layer slurry. In the mixed adhesive slurry, the mass percentage of supercritical carbon dioxide is 20 wt%, based on the mass of the solvent deionized water. A porous polyethylene film with a ceramic coating and a total thickness of approximately 11 μm was selected as the substrate layer. The mixed adhesive slurry was fed into a spray gun and then sprayed onto the surface of the substrate ceramic layer of the diaphragm. Under the action of gas explosion atomization and pressure atomization of supercritical or liquid carbon dioxide, the mixed adhesive slurry was dispersed on the surface of the substrate ceramic layer and formed adhesive particles that adhered. After drying, a PCS diaphragm coating with an average thickness of 1 μm was formed. Relevant preparation parameters are detailed in Table 1. The thickness of the ceramic coating is 2 μm, and the thickness of the substrate layer is 9 μm.

[0070] <Preparation of the positive electrode> Lithium iron phosphate (LiFePO4), conductive carbon black (Super-P), and PVDF binder were mixed at a mass ratio of 97:1:2. N-methylpyrrolidone (NMP) was then added as a solvent and stirred until homogeneous, forming a positive electrode slurry with a solid content of 60 wt%. This slurry was then uniformly coated onto one surface of an 11 μm thick aluminum foil current collector and dried at 85°C. The above steps were repeated on the other surface of the positive electrode. After rolling, a positive electrode sheet with a double-sided coating of positive electrode material layers was obtained. The thickness of the positive electrode material layer on one side was 90 μm.

[0071] <Preparation of Negative Electrode Sheets> Artificial graphite, conductive carbon black (Super-P), sodium carboxymethyl cellulose (CMC-Na), and styrene-butadiene rubber (SBR) were mixed in a mass ratio of 97:1:1.5:0.5. Deionized water was added, and the mixture was stirred until homogeneous, resulting in a negative electrode slurry with a solid content of 55 wt%. The negative electrode slurry was then uniformly coated onto one surface of a 6 μm thick copper foil used as a negative electrode current collector and dried at 105 °C. The above steps were repeated on the other surface of the negative electrode sheet. After rolling, a negative electrode sheet with a double-sided coating of negative electrode material layers was obtained, with a single-sided thickness of 70 μm for each negative electrode material layer.

[0072] <Preparation of Electrolyte> Ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) were mixed in a volume ratio of 1:1:1, dissolved, and thoroughly stirred. The mixture was then placed at 5°C or lower for 12 hours. Lithium hexafluorophosphate (LiPF6) was then added and mixed thoroughly to obtain the electrolyte. The molar concentration of LiPF6 in the electrolyte was 1.0 mol / L.

[0073] <Preparation of Lithium-ion Batteries> The positive electrode, separator, and negative electrode obtained above are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. The resulting cells are then wound to obtain a bare cell. The bare cell is placed in an aluminum alloy square shell, vacuum dried, and then injected with electrolyte. After vacuum sealing, settling, and formation processes, a lithium-ion battery is obtained.

[0074] Examples 2 to 12 Except for adjusting the relevant preparation parameters according to Table 1 in the section on "Preparation of the Separator", the rest is the same as in Example 1.

[0075] Example 13 Except for replacing supercritical carbon dioxide with liquid carbon dioxide in the <Preparation of the diaphragm> section, the rest is the same as in Example 1.

[0076] Examples 14-15 Except for adjusting the Dv50 of the adhesive particles according to Table 2 in the <Preparation of the Separator> section, the rest is the same as in Example 1.

[0077] Comparative Example 1 Except for the fact that supercritical carbon dioxide or liquid carbon dioxide is not added to the initial adhesive layer slurry in the <Preparation of the Separator> section, the rest is the same as in Example 1.

[0078] Comparative Examples 2 to 3 Except for adjusting the percentage of CO2 mass to solvent mass according to Table 1 in the <Preparation of the Separator> section, the rest is the same as in Example 1.

[0079] Table 1: Preparation parameters of Examples 1-12 and Comparative Examples 1-3

[0080] In Table 1, " / " indicates that no relevant preparation parameters exist.

[0081] Test methods and equipment: Solid content test of adhesive slurry: The solid content of PCS slurry was tested according to the standard GB / T 18856.2-2008 Test Methods for Coal-Water Slurry Part 2: Determination of Concentration. A halogen moisture analyzer was used, with a moisture measurement range of 0.01-100%, a moisture content readability of 0.01%, a weighing accuracy of 0.001g, a heating temperature range RT of approximately 150℃, and a tungsten halogen ring lamp as the heating source.

[0082] Viscosity test of adhesive slurry: The viscosity of the adhesive slurry was tested according to the standards ASTM D2196-2018 (Test Method for Determination of Rheological Properties of Non-Newtonian Materials by Rotational Viscometer) and ASTM D4287-2000(2010) (Standard Test Method for Determination of High-Speed ​​Shear Viscosity by Cone-Plate Viscometer), using a digital rotational viscometer and a cone-plate viscometer, at a test temperature of 25°C. Alternatively, a real-time online viscosity monitoring device can be added to the pipeline to monitor the viscosity of the adhesive slurry in real time and obtain real-time viscosity changes.

[0083] Single-sided areal density test of the diaphragm adhesive layer: The test was conducted according to the standard GB / T 20220-2006 "Determination of Average Thickness, Average Thickness of Roll and Area per Unit Mass of Plastic Films and Sheets - Weighing Method", using a 100cm... 2 Five pieces of substrate layer and five pieces of membrane with adhesive layer were cut using a grammage sampler. The weights of each sample were measured and then divided by the sampled area to obtain the areal density of each sample. The difference between the two is the areal density of the amount of adhesive applied. The average value was taken after five tests.

[0084] Compression sampling and adhesion peel strength test of diaphragm and positive electrode: The peel strength of a diaphragm-positive electrode sheet with an adhesive layer was tested according to the standard GB / T 2792-2014, "Test Method for Peel Strength of Adhesive Tapes". After pressing, the sample size was cut to 20mm × 100mm and fixed in the center of the tensile testing machine's clamps. The tensile testing machine was then used to peel the diaphragm and positive electrode sheet along a 180° direction at a speed of 50mm / min, with a test distance of 80mm. Five samples were tested, and the average value was taken. The adhesive force was then used as the average peel strength. The pressing method for the diaphragm and positive electrode sheet was as follows: 100mm × 100mm positive electrode sheet and diaphragm were cut, naturally stacked, and placed in a flatbed press for pressing. The room temperature pressing temperature was 25℃~30℃, the holding time was 30s~60s, and the unit area pressure was 2 MPa~7 MPa.

[0085] Definition and testing of adhesive dot coverage on coating surface: The adhesive dot coverage tester (model: ZYGD-6040FLC, Guangzhou Zhongyi Optoelectronic Technology Co., Ltd.) was used to identify and calculate the surface of the coated diaphragm. Five photos were randomly taken and the average value was taken. The measurement area was 60mm×40mm. The identification and calculation principle is based on the color difference between the non-aqueous adhesive particles and the substrate under an optical microscope. The total area of ​​the adhesive dots was identified and calculated by surface scanning. Then, the coverage was calculated using the total area of ​​the adhesive dots and the area of ​​the measured size.

[0086] Diaphragm single-layer thickness test and standard deviation calculation: Following the thickness test method in section 6.4.1 of the standard GB / T 36363-2018 "Polyolefin Separators for Lithium-ion Batteries", a thickness gauge (model: German Mahr C1202) was used to test the thickness of the coated single-layer separator. A planar probe with a diameter of φ = 8 mm was used, and the test pressure was 0.25 N. Ten tests were performed, and the average value was taken. The standard deviation (σ) is the square root of the average (variance) of the squares of the differences between the thickness at each point and the average thickness, calculated using the following formula:

[0087] Where xi is the thickness at each point. Where N is the average thickness and N is the number of measurement points. The smaller the standard deviation, the more uniform the thickness distribution.

[0088] Average particle size Dv50 test of adhesive dots: The solid particles of the initial adhesive layer slurry were tested by laser particle size analysis according to the standard GB / T 19077-2024 Laser Diffraction Method for Particle Size Analysis. The laser particle size analyzer system (model: Better size 2600) was used, and the average value was taken after three tests.

[0089] Lithium-ion battery energy efficiency test: The lithium-ion battery was subjected to charge-discharge cycles at 25°C using 0.5P charging and discharging, with a charging cutoff voltage of 3.7V and a discharging cutoff voltage of 2.45V, until the battery capacity reached 60% of its initial capacity. Simultaneously, the energy efficiency of the lithium-ion battery after 500 cycles was tested using a constant current method. The energy efficiency was calculated as: (500th cycle discharge energy / 500th cycle charging energy) × 100%.

[0090] Test of the negative electrode interface after full charging: The fully charged cell was disassembled according to the operating specifications. The disassembly room humidity was ≤5%RH and the temperature was 25±3℃. The wrinkles on the negative electrode interface were photographed and recorded. If the negative electrode had 0 folds, it was considered wrinkle-free; if it had 1 to 3 folds, it was considered very slight wrinkle; if it had 4 to 6 folds, it was considered slight wrinkle; and if it had 7 or more folds, it was considered significantly wrinkled.

[0091] Table 2: Membrane physical and electrical properties data for each embodiment and comparative example

[0092] As can be seen from Examples 1 to 15 and Comparative Examples 1 to 3, when supercritical carbon dioxide or liquid carbon dioxide is not added to the initial adhesive slurry (e.g., Comparative Example 1), Q / (S×100F) exceeds the scope of this application, the membrane thickness uniformity is poor, obvious wrinkles appear at the negative electrode interface of the lithium-ion battery, and the room temperature energy efficiency is low; when the amount of supercritical carbon dioxide or liquid carbon dioxide added is too small (e.g., Comparative Example 2), Q / (S×100F) exceeds the scope of this application, although the room temperature energy efficiency of the lithium-ion battery does not decrease significantly, obvious wrinkles appear at the negative electrode interface, and the membrane thickness uniformity is poor; when the amount of supercritical carbon dioxide or liquid carbon dioxide added is too large (e.g., Comparative Example 3), Q / (S×100F) exceeds the scope of this application, the negative electrode interface of the lithium-ion battery shows material shedding, and the room temperature energy efficiency is significantly reduced; while Q / (S×100F) is within the scope of this application, the negative electrode interface of the lithium-ion battery has no wrinkles, the membrane thickness uniformity is better, and it exhibits good room temperature energy efficiency.

[0093] Parameters such as temperature, pressure, initial solid content of the adhesive slurry, and particle size of supercritical or liquid carbon dioxide typically affect the performance of the adhesive layer, thereby influencing the performance of the lithium-ion battery. As can be seen from Examples 5 to 15, by adjusting the above parameters within the scope of this application, the prepared lithium-ion batteries exhibit good interface properties and energy efficiency.

[0094] Figure 1 This is a scanning electron microscope image of the diaphragm surface obtained in Example 1 of this application; Figure 5 This is a scanning electron microscope (SEM) image of the diaphragm surface prepared in Comparative Example 1. From... Figure 1 and Figure 5 The comparison shows that after partial swelling with supercritical carbon dioxide, the particle size and surface roughness of PMMA increase slightly, which is beneficial to improving the adhesion performance of the adhesive layer.

[0095] The foregoing has provided a detailed description of a diaphragm and its preparation method, as well as a battery, energy storage device, and electrical equipment disclosed in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core inventive points of the embodiments of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A diaphragm, characterized in that, It includes a substrate layer and an adhesive layer disposed on at least one surface of the substrate layer, wherein the adhesive layer includes adhesive particles; The diaphragm satisfies the following relationship: 2≤Q / (S×100F)≤40; Wherein, S represents the surface density of the adhesive layer on one side, in g / m³. 2 ; F represents the coverage of the adhesive particles on the surface of the substrate layer; Q represents the average peel strength between the separator and the positive electrode, expressed in N / m.

2. The diaphragm according to claim 1, characterized in that, The diaphragm satisfies the following relationship: 5≤Q / (S×100F)≤25.

3. The diaphragm according to claim 1, characterized in that, The diaphragm satisfies at least one of the following characteristics: a) 0.05 ≤ S ≤ 0.25; b) 1% ≤ F ≤ 10%; c) 1 ≤ Q ≤ 5.

4. The diaphragm according to claim 1, characterized in that, The average particle size Dv50 of the adhesive dots is 0.2μm~3μm.

5. The diaphragm according to any one of claims 1 to 4, characterized in that, The adhesive particles contain a polymer, which includes at least one of polymethyl methacrylate, polyacrylate, polystyrene, and polyvinylidene fluoride modified with supercritical carbon dioxide or liquid carbon dioxide.

6. A method for preparing a diaphragm, characterized in that, Includes the following steps: An initial adhesive layer slurry is prepared, and the solid content of the initial adhesive layer slurry is adjusted to 10%~30%, wherein the solvent of the initial adhesive layer slurry includes water; The initial adhesive slurry is mixed with supercritical carbon dioxide or liquid carbon dioxide to obtain a mixed adhesive slurry. The polymer particles in the mixed adhesive slurry swell under the action of the supercritical carbon dioxide or liquid carbon dioxide. The mass percentage of the supercritical carbon dioxide or liquid carbon dioxide in the mixed adhesive slurry is 1 wt% to 30 wt%, based on the mass of the solvent in the mixed adhesive slurry. The mixed adhesive slurry is sprayed onto the surface of the substrate layer of the diaphragm. Under the action of gas explosion atomization and pressure atomization of supercritical carbon dioxide or liquid carbon dioxide, the mixed adhesive slurry is dispersed on the surface of the substrate layer and forms adhesive particles.

7. The preparation method according to claim 6, characterized in that, The viscosity of the mixed adhesive slurry is 5 mPa·s to 200 mPa·s.

8. The preparation method according to claim 6, characterized in that, The temperature of the supercritical carbon dioxide or the liquid carbon dioxide before mixing is 25℃~50℃, and the pressure is 7.4MPa~25MPa.

9. A battery, characterized in that, It includes the diaphragm according to any one of claims 1 to 5, or the diaphragm prepared by the method according to any one of claims 6 to 8.

10. An energy storage device, characterized in that, It includes a housing and at least one battery as described in claim 9, the battery being housed within the housing.

11. An electrical appliance, characterized in that, The device includes the energy storage device of claim 10, which supplies power to the electrical equipment.

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