High-efficiency closed-pore high-stability slurry, preparation method thereof, lithium ion battery and electric device

Abstract

The application discloses a kind of efficient closed pore high stability slurry and its preparation method, lithium ion battery and electric equipment, it is related to the technical field of lithium battery, wherein, efficient closed pore high stability slurry includes water, core-shell microspheres, thermal stabilizer, wetting aid and dispersion aid, core-shell microspheres include first core-shell microparticle and second core-shell microparticle, wherein, the core of first core-shell microparticle is the mixture of heat conductor and flame retardant, or the combination of any one or more of heat conductor, the shell of first core-shell microparticle is the mixture of heat-sensitive accelerator and heat-sensitive main agent, or the composition of any one or more of heat-sensitive accelerator;The core of second core-shell microparticle is the mixture of heat conductor and flame retardant, or the composition of any one or more of flame retardant, the shell of second core-shell microparticle is the mixture of heat-sensitive accelerator and heat-sensitive main agent, or the composition of any one or more of heat-sensitive main agent.Early fast, synchronous response temperature change, excellent thermal stability and flame retardance are had.

Description

Technical Field

[0001] This application belongs to the field of lithium battery technology, and particularly relates to a high-efficiency closed-cell high-stability slurry and its preparation method, lithium-ion batteries and electrical equipment. Background Technology

[0002] The safety performance of lithium-ion batteries has always been a key factor restricting their large-scale application, especially the thermal runaway issue, which is a focus of industry attention. As a crucial component of the battery, the thermal response characteristics of the separator directly affect the overall safety of the battery. Currently, traditional polyolefin separators (such as PE and PP) mainly rely on the material itself to melt at a specific temperature (typically around 135°C for PE and around 165°C for PP) to achieve pore closure, which is a passive safety mechanism and the pore closure temperature is too high.

[0003] In recent years, phase change materials (PCCs) have been introduced into separator design to block ion transport by undergoing a phase change at a specific temperature. For example, paraffin microspheres or polyethylene microspheres are used as thermosensitive materials in separator coatings. These materials can melt and close the pores when the battery overheats abnormally. However, this approach has inherent drawbacks: 1. Response hysteresis. Polyolefins have high melting phase change enthalpies (e.g., PE has a melting enthalpy of about 200 J / g), requiring a large amount of heat to complete the phase change, resulting in a slow pore-closing response. In the early stages of thermal runaway, this delay may cause the missed optimal intervention window for suppressing thermal runaway. 2. Uneven pore closure. Traditional separators lack an effective heat conduction network, and heat cannot be quickly dissipated when local overheating occurs, easily leading to asynchronous pore closure and forming local short circuit points. 3. Single safety barrier. After pore closure, it relies solely on physical isolation. If the temperature continues to rise, the separator will shrink and rupture, still causing a short circuit. Furthermore, there is no chemical flame-retardant mechanism to inhibit electrolyte combustion. In addition, the adhesion strength between the functional coating and the base film is insufficient at high temperatures, making the coating prone to peeling off.

[0004] Therefore, developing a novel diaphragm coating slurry that can respond quickly and synchronously to temperature changes in the early stages, has excellent thermal stability and flame retardancy, and still adheres firmly to the base film at high temperatures has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This application provides a high-efficiency closed-cell high-stability slurry and its preparation method, lithium-ion batteries and electrical equipment, aiming to solve to some extent the technical problem of how to produce a novel membrane coating slurry with advantages such as early and rapid response to temperature changes, excellent thermal stability and flame retardancy, and strong bonding with the base film at high temperatures.

[0006] In a first aspect, this application provides a high-efficiency closed-cell high-stability slurry, comprising water, core-shell microspheres, a heat stabilizer, and auxiliary additives. The core-shell microspheres comprise first core-shell microparticles and second core-shell microparticles. The core of the first core-shell microspheres is a mixture of a thermally conductive agent and a flame retardant, or any one or more combinations of thermally conductive agents, with the thermally conductive agent content exceeding the flame retardant content. The shell of the first core-shell microspheres is a mixture of a heat-sensitive accelerator and a heat-sensitive main agent, or any one or more combinations of heat-sensitive accelerators, with the heat-sensitive accelerator content exceeding the heat-sensitive main agent content. The core of the second core-shell microspheres is a mixture of a thermally conductive agent and a flame retardant, or a mixture of a thermally conductive agent and a flame retardant. The composition comprises one or more of the following: a flame retardant, wherein the content of the flame retardant is greater than the content of the thermally conductive agent; the shell of the second core-shell microspheres is a mixture of a heat-sensitive accelerator and a heat-sensitive main agent, or a composition of one or more of the heat-sensitive main agents, wherein the content of the heat-sensitive main agent is greater than the content of the heat-sensitive accelerator; the mass ratio of the heat-sensitive main agent to the heat-sensitive accelerator in the core-shell microspheres is 1:9 to 9:1; the auxiliary additives include wetting agents and dispersing agents; the water content is 50 to 73.5 wt%, the core-shell microsphere content is 25 to 40 wt%, the heat stabilizer content is 1 to 5 wt%, and the auxiliary additive content is 0.5 to 5 wt%.

[0007] Furthermore, the melting point of the thermosensitive main agent is greater than that of the thermosensitive accelerator, and the difference between the melting point of the thermosensitive main agent and the melting point of the thermosensitive accelerator is 5~20℃; the particle size of the core-shell microspheres is 0.3~6μm, the shell thickness of the first core-shell microspheres accounts for 10%~25% of the radius of the first core-shell microspheres, and the shell thickness of the second core-shell microspheres accounts for 10%~25% of the radius of the second core-shell microspheres.

[0008] Further, the heat-sensitive accelerator is at least one of Fischer-Tropsch wax, palm wax, hydrogenated castor oil, microcrystalline wax, paraffin wax, lignite wax, erucamide, candelilla wax, stearic acid, stearyl glycyrrhetinic acid ester, oleamide, ethylene-vinyl acetate wax, glyceryl stearate, stearyl alcohol, polycaprolactone, and hydrogenated palm oil.

[0009] The thermosensitive main agent is selected from at least one of stearamide, ethylene-vinyl acetate copolymer, hydrogenated petroleum resin, polyethylene wax, polyacrylate, palmitamide, copolyester, oxidized polyethylene wax, lauramide, myristamide, behenamide, eicosamide, montan wax oxidized derivative, and ethylene acrylic acid copolymer.

[0010] Furthermore, the thermally conductive agent is at least one of the following: single-crystal thermally conductive alumina, zirconium oxide, polycrystalline silicon nitride, aluminum nitride, zinc oxide, magnesium oxide, silicon dioxide, molybdenum oxide, boron nitride, graphene, carbon nanotubes, and carbon fibers.

[0011] The heat stabilizer includes at least one of polyacrylamide, polyacrylate, polyphthalamide, polyacrylonitrile, poly(p-phenylene terephthalamide), polyvinyl alcohol, acrylic acid and derivatives of multi-component copolymers.

[0012] Further, the flame retardant is at least one selected from polyphosphazene, ethoxy-pentafluorocyclotriphosphazene, aluminum hypophosphite, diethyl ethyl phosphonate, dimethoxymethyl phosphate, decabromodiphenyl ethane, triphenyl phosphate, triethyl phosphate, polyphosphate, antimony trioxide, trimethyl phosphate, and trimethyl phosphite.

[0013] The wetting aid comprises at least one of sodium diisooctyl succinate sulfonate, alkylphenol polyoxyethylene ether, aliphatic polyether, polyethylene glycol, sodium alginate, hydroxyethyl cellulose, polyether ester, and polyester.

[0014] The dispersing agent is selected from at least one of the following: acrylic block copolymer, sodium carboxymethyl cellulose, acrylic polymer, sodium polyacrylate, sodium polycarboxylate, ammonium polyacrylate, maleic anhydride copolymer, sodium polystyrene sulfonate, polyacrylate copolymer, sodium lignosulfonate, polyurethane, and polyacrylic acid.

[0015] Secondly, this application provides a method for preparing a high-efficiency closed-cell highly stable slurry, characterized by comprising the following steps:

[0016] S100: Preparation of the first core-shell microparticles;

[0017] S200: Preparation of second core-shell microparticles;

[0018] S300: A first mixture is obtained by initially mixing water, first core-shell microparticles, second core-shell microparticles, and dispersing agent;

[0019] S400: The heat stabilizer is mixed with the first mixture to obtain the second mixture;

[0020] S500: Water, wetting agent, and second mixture are mixed to obtain a high-efficiency closed-cell, highly stable slurry.

[0021] Further, step S100 includes the following steps:

[0022] S101: Add the first core-shell component to a planetary mixer. While stirring, add the first core-shell component in batches and slowly to obtain the first premixed liquid. The stirring speed is 400~800 rpm and the stirring time is 20~70 min.

[0023] S102: The first premixed liquid is transferred to a high-speed homogenizer for homogenization and dispersion to obtain the second premixed liquid. The dispersion speed is 1000~2000 rpm and the dispersion time is 10~20 min.

[0024] S103: Transfer the second premix to a magnetic stirrer, add water and stir at low speed to obtain the first mixture. The stirring speed is 50~300 rpm.

[0025] S104: The first mixture is filtered and vacuum degassed to obtain the first spray-drying feed liquid;

[0026] S105: The first spray drying feed liquid is transferred to a spray dryer for spray drying to obtain the first core-shell powder. The inlet temperature of the spray dryer is 80~110℃, the outlet temperature is 45~65℃, the feed rate is 6~10mL / min, the atomization pressure is 1.5~2.5bar, and the drying medium is nitrogen.

[0027] S106: The dried first core-shell powder is collected using a cyclone separator and then heat-treated in a vacuum drying oven to obtain the first core-shell microparticles, wherein the heat treatment temperature is 40~60℃ and the time is 1~3.5h.

[0028] Further, step S200 includes the following steps:

[0029] S201: Add the second core-shell component to the planetary mixer. While stirring, add the second core-shell component in batches and slowly to obtain the third premix. The stirring speed is 300~800 rpm and the stirring time is 30~90 min.

[0030] S202: The third premixed liquid is transferred to a high-speed homogenizer for homogenization and dispersion to obtain the fourth premixed liquid. The dispersion speed is 1000~2000 rpm and the dispersion time is 10~20 min.

[0031] S203: Transfer the fourth premix to a magnetic stirrer, add water and stir at low speed to obtain the second mixture. The stirring speed is 50~300 rpm.

[0032] S204: The second mixture is filtered and vacuum degassed to obtain the second spray-drying feed liquid;

[0033] S205: The second spray drying feed liquid is transferred to a spray dryer for spray drying to obtain the second core-shell powder. The inlet temperature of the spray dryer is 90~120℃, the outlet temperature is 55~75℃, the feed rate is 5~8mL / min, the atomization pressure is 1.5~3.0bar, and the drying medium is nitrogen.

[0034] S206: The dried first core-shell powder is collected using a cyclone separator and then heat-treated in a vacuum drying oven to obtain heat-sensitive agent core-shell microparticles, wherein the heat treatment temperature is 45~70℃ and the time is 1~2h.

[0035] Thirdly, this application provides a method for preparing a lithium-ion battery, comprising the following steps:

[0036] S100: A high-efficiency closed-cell high-stability slurry is coated on the first side of the base membrane, and then a high-efficiency closed-cell high-stability slurry is coated on the second side of the base membrane opposite to the first side, to obtain a safety composite membrane with a high-efficiency closed-cell high-stability slurry.

[0037] S200: The first side of the safety composite separator is in contact with the positive electrode of the battery, and the second side of the safety composite separator is in contact with the negative electrode of the battery. The cells are then manufactured by winding or stacking processes.

[0038] S300: Assemble the cells to obtain a lithium-ion battery with a high-efficiency closed-cell, high-stability slurry.

[0039] Fourthly, this application provides an electrical device that uses a lithium-ion battery prepared by the above-described method for preparing a lithium-ion battery.

[0040] It is understood that the beneficial effects of the second to fourth aspects mentioned above can be found in the relevant descriptions in the first aspect above, and will not be repeated here.

[0041] The advantages of this application compared to the prior art are:

[0042] This application discloses a high-efficiency closed-cell high-stability slurry, its preparation method, a lithium-ion battery, and related electrical equipment. The high-efficiency closed-cell high-stability slurry is coated onto the interlayer membrane between the positive and negative electrodes of the battery. The slurry comprises water, core-shell microspheres, a heat stabilizer, and auxiliary agents. The core-shell microspheres utilize a synergistic system of "thermally sensitive main agent + thermally sensitive promoter + thermally conductive agent + flame retardant" to transform the existing passively responsive coating membrane into an actively synergistically responsive coating membrane. This allows the high-efficiency closed-cell high-stability coating to achieve efficient and uniform pore closing when the battery experiences abnormal heating. Specifically:

[0043] (1) The heat-sensitive accelerator can effectively reduce the melting phase transition enthalpy of the heat-sensitive agent, enabling the heat-sensitive agent to undergo rapid melting and flow in a lower heat environment to achieve membrane pore closing, thus solving the problem of membrane pore closing response hysteresis.

[0044] (2) By establishing a thermally conductive network inside the coating, the thermally conductive agent can rapidly diffuse local hot spots to the entire coating. Good heat distribution helps maintain a consistent reaction state throughout the battery, delays internal resistance and capacity differentiation caused by temperature differences, and improves overall cycle stability. More importantly, it ensures that the composite material of the thermally sensitive agent and the thermally sensitive promoter, i.e., the core-shell microspheres, can be heated and responded uniformly and synchronously, solving the problem of uneven pore closure where some areas of the separator have melted and closed pores while other areas have not yet responded.

[0045] (3) At high temperatures, the flame retardant can actively inhibit the combustion chain reaction of the electrolyte, realizing the upgrade from "physical isolation" to "chemical flame retardancy"; even after the heat-sensitive main agent melts, the heat-resistant network formed by the heat-resistant binder can still maintain the skeleton structure of the coating, preventing the high-efficiency closed-cell high-stability coating from shrinking, powdering or falling off at high temperatures, providing mechanical integrity for the diaphragm at high temperatures, realizing a continuous safety barrier after pore closure, and solving the thermal inertia problems such as diaphragm shrinkage and combustion that may still occur after the diaphragm is closed.

[0046] (4) Adding auxiliary agents improves the stability of the high-efficiency closed-cell high-stability coating. Among them, the wetting agent can reduce the surface tension of the coating to promote the spread and penetration of liquid on the solid surface, ensuring that the coating can flow and achieve rapid response to closed pores when the battery is thermally runaway. The dispersing agent can ensure that the mixture in the coating can be dispersed evenly by increasing the repulsive force between particles.

[0047] Based on this, the high-efficiency closed-cell high-stability coating can quickly respond to complete pore closure when the battery is abnormally heated. After pore closure, the separator can not only physically prevent short circuits, but also chemically prevent fires, thus solving the safety problem of lithium batteries, while taking into account electrochemical performance such as cycle life. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art 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.

[0049] Figure 1 This is a schematic diagram of the structure of the high-efficiency closed-cell high-stability coating of the present invention in use;

[0050] Figure 2 The differential scanning calorimetry (DSC) test results are for the membranes prepared in Example 1 and Comparative Examples 1 and 2 of this invention.

[0051] Figure 3 The DC internal resistance (DCR) test results of the batteries prepared with the separators of Example 1 and Comparative Example 8 of the present invention;

[0052] Figure 4 The results of room temperature cycle discharge capacity retention tests are for batteries prepared with the separators of Example 1 and Comparative Example 8 of this invention. Detailed Implementation

[0053] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0054] In this application, the term "and / or" describes 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, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0055] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, a~b (i.e., a and b), a~c, b~c, or a~b~c, where a, b, and c can be single or multiple.

[0056] The terms "first" and "second" are used only to describe the purpose and to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the provisions of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0057] The terminology used in the embodiments of this application is for the purpose of describing particular implementations only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the implementations of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0058] It should be understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation rules of this application.

[0059] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0060] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0061] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application are available on the market or can be prepared by existing methods.

[0062] The coatings generated by existing battery separator slurries often suffer from problems such as delayed thermal response, uneven pore size, and limited barrier properties.

[0063] Reference Figure 1To address the aforementioned problems to some extent, the first aspect of this application provides a high-efficiency closed-cell, high-stability slurry, comprising water, core-shell microspheres, a heat stabilizer, and auxiliary additives. The core-shell microspheres include first core-shell microparticles and second core-shell microparticles. The core of the first core-shell microparticles is a mixture of a thermally conductive agent and a flame retardant, or any one or more combinations of thermally conductive agents, with the thermally conductive agent content exceeding the flame retardant content. The shell of the first core-shell microparticles is a mixture of a heat-sensitive accelerator and a heat-sensitive main agent, or any one or more combinations of heat-sensitive accelerators, with the heat-sensitive accelerator content exceeding the heat-sensitive main agent content. The core of the second core-shell microparticles is a thermally conductive agent and a flame retardant. The mixture of the above-mentioned components, or a combination of one or more of the flame retardants, wherein the content of the flame retardant is greater than the content of the thermally conductive agent, wherein the shell of the second core-shell microspheres is a mixture of the heat-sensitive accelerator and the heat-sensitive main agent, or a combination of one or more of the heat-sensitive main agent, wherein the content of the heat-sensitive main agent is greater than the content of the heat-sensitive accelerator; the mass ratio of the heat-sensitive main agent to the heat-sensitive accelerator in the core-shell microspheres is 1:9 to 9:1; the auxiliary additives include wetting agents and dispersing agents; the water content is 50 to 73.5 wt%, the core-shell microsphere content is 25 to 40 wt%, the heat stabilizer content is 1 to 5 wt%, and the auxiliary additive content is 0.5 to 5 wt%.

[0064] In this embodiment, the high-efficiency closed-cell high-stability slurry comprises water, core-shell microspheres, heat stabilizer and auxiliary agents, wherein the water content is 50-73.5%, the core-shell microsphere content is 25-40%, the heat stabilizer content is 1-5%, and the auxiliary agent content is 0.5-5%, wherein water is used as a solvent, and the core-shell microspheres, heat stabilizer and auxiliary agents are used as solutes. In use, the slurry is coated on both sides of the base film and dried, ensuring that the core-shell microspheres, heat stabilizer, and auxiliary agents are uniformly coated on the base film surface. The first core-shell microspheres must contain a thermally conductive agent and a thermosensitive accelerator, while the second core-shell microspheres must contain a flame retardant and a thermosensitive main agent. When the battery overheats abnormally, the shells of the first and second core-shell microspheres melt and mix. At this time, the thermosensitive accelerator can reduce the melting phase transition enthalpy of the thermosensitive main agent, allowing the high-efficiency closed-cell, high-stability coating to melt rapidly to seal the micropores on the separator. Simultaneously, the core of the first core-shell microspheres releases the thermally conductive agent, and the core of the second core-shell microspheres releases the flame retardant. The thermally conductive agent can establish a thermally conductive network within the coating, rapidly diffusing local hot spots to the entire coating. This ensures that the fusion material of the thermosensitive main agent and the thermosensitive accelerator, i.e., the core-shell microspheres, can be heated and responded to uniformly and synchronously, avoiding the inconsistency problem of some areas melting while others have not yet responded. At the same time, the stabilizing system of "flame retardant + heat stabilizer" achieves a continuous safety barrier after pore closure. Even after the heat-sensitive main agent melts, the network of heat-resistant binders formed by the heat stabilizer can still maintain the skeleton structure of the coating, preventing the high-efficiency closed-cell high-stability coating from shrinking, powdering or falling off at high temperatures, and providing mechanical integrity for the diaphragm at high temperatures; the flame retardant can actively inhibit the combustion chain reaction of the electrolyte at high temperatures, realizing the upgrade from "physical isolation" to "chemical flame retardancy", avoiding thermal inertia problems such as diaphragm shrinkage and combustion that may still occur after the pores are closed.

[0065] In practice, the ratio of the total mass of the thermosensitive main agent contained in the first and second core-shell microspheres to the total mass of the thermosensitive accelerator contained in the core-shell microspheres is controlled between 1:9 and 9:1. When the proportion of the thermosensitive accelerator is too high (close to 1:9), the triggering is very sensitive, but the pore-closure strength may be insufficient due to insufficient main material, resulting in a weak physical barrier. When the proportion of the thermosensitive main agent is too high (close to 9:1), the physical barrier after pore closure is strong, but the thermal response sensitivity may be insufficient due to the low content of the thermosensitive accelerator, resulting in a sluggish response and a high start-up temperature. Therefore, it is necessary to ensure that the mass ratio of the thermosensitive main agent to the thermosensitive accelerator is controlled between 1:9 and 9:1, so that both materials have sufficient quantity to play their core role, which can effectively trigger and fully close the pores.

[0066] Preferably, the mass ratio of the thermosensitive agent to the thermosensitive accelerator is 1:1, achieving a two-way balance between thermal response sensitivity and pore-closing strength. The thermosensitive accelerator ensures stable start-up temperature, moderate response speed, and no significant hysteresis or false triggering; the thermosensitive agent dissolves after the response to seal the micropores on the diaphragm. This ratio is suitable for general scenarios without special operating conditions and is the preferred solution that balances reliability and economy.

[0067] In other embodiments, the mass ratio of the thermosensitive agent to the thermosensitive accelerator is 3:7. This increases the thermosensitive accelerator's sensitivity to achieve thermal response while maintaining the proportion of the thermosensitive agent, compensating for insufficient closed-cell strength under extreme ratios and forming a continuous and durable physical barrier. This ratio is suitable for operating conditions where equipment starts and stops frequently, ambient temperature fluctuates little, and a rapid response to temperature changes is required.

[0068] Specifically, regarding the ratio of the first core-shell microparticles to the second core-shell microparticles, when both the first and second core-shell microparticles are prepared using a single material, the core of the first core-shell microparticle is a thermally conductive agent, and the shell is a thermosensitive accelerator; the core of the second core-shell microparticle is a flame retardant, and the shell is a thermosensitive main agent. With this configuration, the first core-shell microparticles have a fast thermal conductivity and high thermal response sensitivity, while the second core-shell microparticles are highly efficient at flame retardancy and form a highly tough closed-cell barrier. The two work together to ensure uniform response and stable protection, simplifying the process and making it more suitable for large-scale mass production.

[0069] When the first and second core-shell microparticles are prepared using a hybrid material, as a preferred embodiment, the mass ratio of thermally conductive agent to flame retardant in the core of the first core-shell microparticle is 8:2, balancing rapid thermal conduction and basic flame retardancy; the mass ratio of the thermosensitive main agent to the thermosensitive accelerator in the shell is 2:8, ensuring high-sensitivity triggering while compensating for the shortness of closed-cell strength. In the second core-shell microparticle, the mass ratio of flame retardant to thermally conductive agent in the core is 8:2, enhancing flame retardant performance while transmitting thermal signals; the mass ratio of the thermosensitive main agent to the thermosensitive accelerator in the shell is 8:2, ensuring a high-strength closed-cell barrier while optimizing response speed.

[0070] In other embodiments, the mass ratio of thermally conductive agent to flame retardant in the first core-shell microparticle core is 7:3, which improves flame retardant performance while ensuring efficient thermal conductivity, making it suitable for scenarios with basic flame retardant requirements; the mass ratio of heat-sensitive main agent to heat-sensitive accelerator in the shell is 3:7, which balances high-sensitivity triggering characteristics while enhancing the mechanical strength of the closed-cell structure and resisting minor media impacts. In the second core-shell microparticle core, the mass ratio of flame retardant to thermally conductive agent is 7:3, which strengthens the core flame retardant effect while optimizing heat signal conduction efficiency, avoiding local triggering lag due to insufficient thermal conductivity; the mass ratio of heat-sensitive main agent to heat-sensitive accelerator in the shell is 7:3, which accelerates the response speed while ensuring a high-strength closed-cell barrier, making it suitable for complex operating conditions with frequent temperature fluctuations.

[0071] Furthermore, the melting point difference between the thermosensitive main agent and the thermosensitive accelerator is 5~20℃; the particle size of the core-shell microparticles is 0.3~6μm, the shell thickness of the first core-shell microparticle accounts for 20%~50% of the total diameter of the first core-shell microparticles, and the shell thickness of the second core-shell microparticles accounts for 20%~50% of the total diameter of the second core-shell microparticles.

[0072] In this embodiment, the melting point difference between the thermosensitive main agent and the thermosensitive accelerator is 5-20°C. This melting point difference allows for relay-style synergistic melting, ensuring rapid and thorough pore closing. Specifically, the thermosensitive accelerator, with its lower melting point, melts before the thermosensitive main agent, altering its enthalpy of phase transition and lowering it. This allows the entire coating system to initiate the pore-closing process at a lower temperature than the pure thermosensitive main agent, resulting in an earlier response. If the melting point difference is too large (>20°C), the thermosensitive accelerator may completely vaporize or leak away before the thermosensitive main agent begins to melt, causing response failure. If the melting point difference is <5°C, the synergistic effect is not significant. Preferably, the melting point difference between the thermosensitive main agent and the thermosensitive accelerator is 10°C. When using a melting point difference of 10℃, compared with a system containing a thermosensitive main agent and a thermosensitive accelerator but with a melting point difference of 20℃, the closed-cell response speed is increased by more than 30%, and the closed-cell barrier formed after melting is continuous and dense, without pores or cracks.

[0073] Then, the ratio of core-shell microparticle size to shell thickness is defined. Specifically, the particle size of the core-shell microparticles is matched to the porosity and thickness of the battery separator itself. For core-shell microparticles, a particle size ≥ 0.3 μm ensures sufficient structural strength, preventing damage during coating and battery cycling. Simultaneously, the particle size is not so small as to clog the micropores of the separator, affecting normal ion conduction. For core-shell microparticles, a particle size ≤ 6 μm ensures the formation of a thin and dense coating. Excessively large particles result in an overly thick and uneven coating, affecting the battery's energy density and internal resistance. This particle size range ensures the coating's uniformity, density, and good coverage of the substrate separator. Simultaneously, a sufficiently thick shell (≥ 20%) ensures the formation of a continuous and complete coating layer, effectively protecting the core material (thermal conductive agent or flame retardant) before reaching a specific temperature, preventing premature leakage or adverse reactions with surrounding components.

[0074] Meanwhile, the shell thickness of the first core-shell microparticle is 10% to 25% of its own radius, and the shell thickness of the second core-shell microparticle is 10% to 25% of its own radius: the shell thickness ratio is not less than 10%, which can form a continuous and complete coating layer, effectively protecting the core material (thermal conductive agent or flame retardant) before reaching the trigger temperature, avoiding premature leakage or adverse reactions with surrounding components, and the loading of heat sensitizer in the shell is sufficient to complete the melting and pore-closing task; the shell thickness ratio is not higher than 25%, which can avoid excessive compression of the core volume, ensure that the core can load a sufficient amount of functional material, and ensure that the thermal conductivity or flame retardant performance meets the usage requirements.

[0075] Preferably, the core-shell microparticles have a particle size of 1~3μm, and the shell thickness of both the first and second core-shell microparticles accounts for 15%~20% of their respective radii. These preferred parameters achieve a precise balance of performance. The 1~3μm particle size is suitable for the pore size of the battery separator, taking into account both structural strength and coating uniformity, without affecting ion conduction efficiency. The 15%~20% shell thickness radius ratio ensures sufficient heat-sensitive agent and complete coating, while reserving ample space for core functional materials. Ultimately, the slurry possesses comprehensive performance characteristics of rapid pore-closing response, stable physical barrier, and efficient thermal conductivity and flame retardancy.

[0076] Further, the heat-sensitive accelerator is at least one of Fischer-Tropsch wax, palm wax, hydrogenated castor oil, microcrystalline wax, paraffin wax, lignite wax, erucamide, candelilla wax, stearic acid, stearyl glycyrrhetinic acid ester, oleamide, ethylene-vinyl acetate wax, glyceryl stearate, stearyl alcohol, polycaprolactone, and hydrogenated palm oil; the heat-sensitive main agent is selected from at least one of stearamide, ethylene-vinyl acetate copolymer, hydrogenated petroleum resin, polyethylene wax, polyacrylate, palmamide, copolymer polyester, oxidized polyethylene wax, lauramide, myristamide, behenamide, eicosamide, montan wax oxidation derivative, and ethylene acrylic acid copolymer.

[0077] In this embodiment, the materials of the heat-sensitive accelerator are all organic materials with well-defined melting points, good compatibility, and easy melting. As "heat-sensitive accelerators", the core function of these substances is to effectively destroy the crystal structure of the heat-sensitive main agent by being compatible and co-melted with the "heat-sensitive main agent" at the molecular level, thereby significantly reducing the energy required for its melting.

[0078] The materials used in the thermosensitive agent are all polymers or high molecular weight materials that can transform from a solid state to a molten and flowing state at a specific temperature. When the battery abnormally heats up and reaches its melting point, the thermosensitive agent rapidly melts and flows to block the micropores of the separator, thereby cutting off the ion flow and achieving efficient pore closure.

[0079] Further, the thermally conductive agent is at least one selected from monocrystalline thermally conductive alumina, zirconium oxide, polycrystalline silicon nitride, aluminum nitride, zinc oxide, magnesium oxide, silicon dioxide, molybdenum oxide, boron nitride, graphene, carbon nanotubes, and carbon fibers; the thermal stabilizer includes at least one selected from polyacrylamide, polyacrylate, poly(phthalamide), polyacrylonitrile, poly(p-phenylene terephthalamide), polyvinyl alcohol, acrylic acid, and multi-component copolymers of their derivatives.

[0080] In this embodiment, the thermal conductive agents are all made of materials with high thermal conductivity. These thermal conductive agents are in contact with each other inside the coating formed by the slurry, forming an effective heat conduction path and network. When a localized abnormal increase in heat occurs inside the battery, the heat will not just accumulate at one point, but will rapidly diffuse to the entire coating through this network.

[0081] The materials used in heat stabilizers are all polymers with high heat resistance, high mechanical strength, or the ability to form a three-dimensional network structure. When the heat-sensitive main agent and heat-sensitive promoter melt and flow at high temperatures to achieve the "cell-closing" function, the heat stabilizer, due to its higher glass transition temperature, can remain solid, thus forming a physical framework. This prevents the coating formed by the slurry from softening at high temperatures and shrinking or curling on the separator, which would lead to a short circuit due to direct contact between the positive and negative large areas. The heat stabilizer can also bind the molten components together, maintaining the integrity of the coating. Even after cell closure is complete, the framework formed by the heat stabilizer still exists, together with the melted and solidified heat-sensitive main agent, providing a robust physical defense for the battery and preventing further escalation of thermal runaway.

[0082] Further, the flame retardant is at least one of polyphosphazene, ethoxy-pentafluorocyclotriphosphazene, aluminum hypophosphite, diethyl ethyl phosphonate, dimethoxymethyl phosphate, decabromodiphenyl ethane, triphenyl phosphate, triethyl phosphate, polyphosphate, antimony trioxide, trimethyl phosphate, and trimethyl phosphite; the wetting aid comprises at least one of sodium diisooctyl succinate sulfonate, alkylphenol polyoxyethylene ether, aliphatic polyether, polyethylene glycol, sodium alginate, hydroxyethyl cellulose, polyether ester, and polyester; the dispersing aid is selected from at least one of acrylic block copolymer, sodium carboxymethyl cellulose, acrylic polymer, sodium polyacrylate, sodium polycarboxylate, ammonium polyacrylate, maleic anhydride copolymer, sodium polystyrene sulfonate, polyacrylate copolymer, sodium lignosulfonate, polyurethane, and polyacrylic acid.

[0083] In this embodiment, the flame retardant provides an upgrade from "physical isolation" to "chemical flame retardancy" for the entire invention, achieving multiple safety protections. It is key to solving the most critical aspect of battery thermal runaway—fire and explosion. When the battery temperature is extremely high, causing the electrolyte to decompose and potentially burn, these flame retardants are activated, actively inhibiting combustion. This allows the separator coating to not only passively cut off the current but also actively extinguish or prevent the generation of open flames. Normal state: The flame retardant is encapsulated by the shell of the core-shell microparticles, isolated from the electrolyte, and does not affect the normal electrochemical performance of the battery. During thermal runaway: First, the shell melts to achieve physical pore closure. Subsequently, the molten shell releases the flame retardant from the core. The released flame retardant rapidly disperses into the surrounding high-temperature environment and electrolyte, achieving chemical flame retardancy.

[0084] Wetting aids are crucial for ensuring the uniform preparation of highly efficient, closed-cell, and stable slurries. They guarantee the slurry's uniformity, and together with dispersing aids, ensure the uniform distribution of functional particles, allowing the thermal conductivity and thermal response networks to function efficiently and consistently. Dispersing aids ensure the synergistic effect of all functional components, increasing interparticle repulsion to guarantee uniform dispersion of the mixtures within the coating.

[0085] This application also discloses a method for preparing a high-efficiency closed-cell high-stability slurry, which includes the following steps:

[0086] S100: Preparation of the first core-shell microparticles;

[0087] S200: Preparation of second core-shell microparticles;

[0088] S300: A first mixture is obtained by initially mixing water, first core-shell particles, second core-shell particles, and dispersing agent.

[0089] S400: The heat stabilizer is mixed with the first mixture to obtain the second mixture;

[0090] S500: Water, wetting agent, and a second mixture are mixed to obtain a highly efficient closed-cell, highly stable coating.

[0091] In this embodiment, for step S100, the core of the first core-shell microparticle is a mixture of a thermally conductive agent and a flame retardant, or a combination of any one or more thermally conductive agents, and the content of the thermally conductive agent is greater than the content of the flame retardant; the shell of the first core-shell microparticle is a mixture of a heat-sensitive accelerator and a heat-sensitive main agent, or a combination of any one or more heat-sensitive accelerators, and the content of the heat-sensitive accelerator is greater than the content of the heat-sensitive main agent.

[0092] For step S200, the core of the second core-shell microparticle is a mixture of a thermally conductive agent and a flame retardant, or a combination of one or more flame retardants, and the content of the flame retardant is greater than the content of the thermally conductive agent. The shell of the second core-shell microparticle is a mixture of a heat-sensitive accelerator and a heat-sensitive main agent, or a combination of one or more heat-sensitive main agents, and the content of the heat-sensitive main agent is greater than the content of the heat-sensitive accelerator.

[0093] In step S300, the dispersing agent acts on the core-shell microspheres to ensure they are fully dispersed in the slurry, preventing agglomeration and thus guaranteeing their uniform distribution and independent functionality in the final coating. This step ensures the effectiveness of the thermal conduction network and thermal response units.

[0094] For step S400, the heat stabilizer is typically a high-molecular-weight polymer with thickening or gelling properties. Adding it too early may result in excessively high slurry viscosity, making it difficult to disperse the core-shell microspheres evenly. Adding it after the dispersion step ensures good particle dispersion before using the heat stabilizer to build the overall stability and bonding strength of the slurry.

[0095] In step S500, the wetting agent is added last, which can most effectively adjust the final surface tension of the slurry and ensure the uniformity of the generated slurry. The uniform distribution of functional particles is guaranteed by the wetting agent and the dispersing agent.

[0096] Further, step S100 includes the following steps:

[0097] S101: Add the first core-shell component to a planetary mixer. While stirring, add the first core-shell component in batches and slowly to obtain the first premixed liquid. The stirring speed is 400~800 rpm and the stirring time is 20~70 min.

[0098] S102: The first premixed liquid is transferred to a high-speed homogenizer for homogenization and dispersion to obtain the second premixed liquid. The dispersion speed is 1000~2000 rpm and the dispersion time is 10~20 min.

[0099] S103: Transfer the second premix to a magnetic stirrer, add water and stir at low speed to obtain the first mixture. The stirring speed is 50~300 rpm.

[0100] S104: The first mixture is filtered and vacuum degassed to obtain the first spray-drying feed liquid;

[0101] S105: The first spray drying feed liquid is transferred to a spray dryer for spray drying to obtain the first core-shell powder. The inlet temperature of the spray dryer is 80~110℃, the outlet temperature is 45~65℃, the feed rate is 6~10mL / min, the atomization pressure is 1.5~2.5bar, and the drying medium is nitrogen.

[0102] S106: The dried first core-shell powder is collected using a cyclone separator and then heat-treated in a vacuum drying oven to obtain the first core-shell microparticles, wherein the heat treatment temperature is 40~60℃ and the time is 1~3.5h.

[0103] In this embodiment, step S101 ensures that the thermally conductive agent is initially coated by the heat-sensitive accelerator emulsion. To ensure uniform coating during actual mixing, a trace amount of auxiliary agent can be added simultaneously with the first core-shell component when it is added to the planetary mixer for mixing. Steps S102-S103 involve continuous stirring to fully mix the components, resulting in a first mixture with a certain viscosity. Specifically, the first mixture has a solid content of 20%-50% and a viscosity of 80-300 mPa·s. Step S104 involves filtering and vacuum degassing the first mixture to obtain a first spray-drying feed liquid. Step S105 uses spray drying technology with clearly defined parameters. The atomized microdroplets are instantly dried in hot nitrogen, and the heat-sensitive accelerator on the droplet surface rapidly solidifies, coating the internal thermally conductive agent. Step S106 removes residual trace amounts of moisture or solvent from the particles, making the first core-shell microparticles more stable.

[0104] Further, step S200 includes the following steps:

[0105] S201: Add the second core-shell component to a planetary mixer. While stirring, add the second core-shell component in batches and slowly to obtain the third premix. The stirring speed is 300~800 rpm and the stirring time is 30~90 min.

[0106] S202: The third premixed liquid is transferred to a high-speed homogenizer for homogenization and dispersion to obtain the fourth premixed liquid. The dispersion speed is 1000~2000 rpm and the dispersion time is 10~20 min.

[0107] S203: Transfer the fourth premix to a magnetic stirrer, add water and stir at low speed to obtain the second mixture. The stirring speed is 50~300 rpm.

[0108] S204: The second mixture is filtered and vacuum degassed to obtain the second spray-drying feed liquid;

[0109] S205: The second spray drying feed liquid is transferred to a spray dryer for spray drying to obtain the second core-shell powder. The inlet temperature of the spray dryer is 90~120℃, the outlet temperature is 55~75℃, the feed rate is 5~8mL / min, the atomization pressure is 1.5~3.0bar, and the drying medium is nitrogen.

[0110] S206: The dried first core-shell powder is collected using a cyclone separator and then heat-treated in a vacuum drying oven to obtain heat-sensitive agent core-shell microparticles, wherein the heat treatment temperature is 45~70℃ and the time is 1~2h.

[0111] In this embodiment, the above is the preparation process of the second core-shell microparticles, ensuring that under normal conditions, the flame retardant is tightly encapsulated by the heat-sensitive main agent shell and isolated from the electrolyte; under thermal runaway conditions, the heat-sensitive main agent shell melts first, achieving closed pores.

[0112] This application also discloses a method for preparing a lithium-ion battery, comprising the following steps:

[0113] S100: The above-mentioned high-efficiency closed-cell high-stability slurry is coated on the first side of the base membrane, and then the high-efficiency closed-cell high-stability slurry is coated on the second side of the base membrane opposite to the first side to obtain a safety composite membrane with high-efficiency closed-cell high-stability slurry.

[0114] S200: The first side of the safety composite separator is in contact with the positive electrode of the battery, and the second side of the safety composite separator is in contact with the negative electrode of the battery. The cells are then manufactured by winding or stacking processes.

[0115] S300: Assemble the cells to obtain a lithium-ion battery with a high-efficiency closed-cell, high-stability slurry.

[0116] This application also discloses an electrical device that uses a lithium-ion battery prepared by the above-described method for preparing lithium-ion batteries. Therefore, the electrical device includes all the beneficial effects of the lithium-ion battery prepared by the above-described method for preparing lithium-ion batteries.

[0117] The technical solution of this application will be illustrated below through specific embodiments and comparative examples.

[0118] The preparation of a high-efficiency, closed-cell, high-stability slurry includes the following embodiments:

[0119] Example 1: Both the first and second core-shell microparticles were prepared using a single material, specifically including the following steps:

[0120] S100: Preparation of the first core-shell microparticles:

[0121] A planetary mixer was added to 416.7g of palm wax solution (30% solid content). The mixer was then turned on, and 50g of single-crystal thermally conductive alumina powder was slowly and gradually poured in during continuous medium-speed mechanical stirring (parameter setting: 500rpm, 40min) to form a first premix. The first premix was then transferred to a high-speed homogenizer for homogenization and dispersion (parameter setting: 1600rpm, 15min) to form a homogeneous second premix. The second premix was then transferred to a magnetic stirrer, and 40.24g of deionized water was added. The mixture was stirred at low speed (parameter setting: 200rpm, 15min) to obtain a first mixture (with a solid content of 34.55% and a viscosity of 88mPa·s). After filtration and vacuum degassing (parameter setting: 10min), a homogeneous first spray-drying feed liquid was obtained. The first spray-drying feed solution was loaded into the feed flask of a peristaltic pump (while maintaining continuous slow stirring of the feed solution) and spray-dried (ice-water bath, parameters: inlet temperature 95℃, outlet temperature 55℃; feed rate 8mL / min; dual-fluid nozzle, atomization pressure 2.0bar; nitrogen as drying medium). The dried core-shell powder was collected by a cyclone separator and finally heat-treated in a vacuum drying oven (parameter settings: 50℃, 2h) to obtain the first core-shell microparticles. In the actual preparation process, in order to fully mix the palm wax solution and alumina powder, a certain amount of auxiliary agents can be added at the same time as the palm wax solution is added to the planetary mixer. Specifically, 1.46g of sodium polyacrylate solution (90% solid content) and 2.19g of sodium carboxymethyl cellulose solution (2% solid content) can be added.

[0122] S200: Preparation of second core-shell microparticles;

[0123] A planetary mixer was added to 312.5g of polyethylene wax solution (40% solid content). The mixer was turned on and 30g of polyphosphazene was slowly and gradually added in batches while continuously stirring at medium speed (400 rpm, 40 min) to form a third premix. The third premix was then transferred to a high-speed homogenizer for homogenization and dispersion to obtain a uniform fourth premix (1600 rpm, 15 min). The fourth premix was then transferred to a magnetic stirrer, and 55.26g of deionized water was added. The mixture was stirred at low speed (300 rpm, 20 min) to obtain a second mixture (38.44% solid content, 190 mPa·s viscosity). After filtration and vacuum degassing (8 min), a uniform second spray-drying feed solution was obtained. The second spray-drying feed solution was loaded into the feed flask of a peristaltic pump (keeping the feed solution continuously and slowly stirred, parameter setting: 200 rpm) for spray drying (parameter settings: inlet temperature 100℃, outlet temperature 60℃; feed rate 6 mL / min; dual-fluid nozzle, atomization pressure 1.8 bar; nitrogen as drying medium). The dried core-shell powder was collected by a cyclone separator and finally heat-treated in a vacuum drying oven (parameter settings: 60℃, 1.5 h) to obtain the second core-shell microparticles. In the actual preparation process, in order to fully mix the polyethylene wax solution and polyphosphazene, a certain amount of auxiliary agent can be added at the same time as the polyethylene wax solution is added to the planetary mixer. Specifically, 3.75 g of polyether-modified styrene-maleic anhydride block copolymer solution (solid content 40%) and 4 g of associative polyurethane (solid content 25%) can be added.

[0124] S300: A first mixture is prepared by mixing 207.3g of water, 60g of first core-shell microparticles, 139.5g of second core-shell microparticles, and a dispersing agent using a planetary mixer. The conditions for the first mixing are: a stirring speed of 300 rpm, a time of 40 min, and a temperature of 25°C. The dispersing agent used is 100g of sodium carboxymethyl cellulose solution (solid content 2%) and 27g of acrylic polymer (solid content 40%).

[0125] S400: The heat stabilizer and the first mixture are mixed by stirring with a planetary mixer to obtain a second mixture; the conditions for the second mixing are: stirring speed of 400 rpm, time of 25 min, and temperature of 25℃; wherein, the heat stabilizer is made by mixing 48 g of polyacrylamide solution (solid content 20%) and 51.58 g of polyacrylate solution (solid content 28.5%).

[0126] S500: A third mixture containing 85.9g water, 1.07g sodium diisooctyl succinate sulfonate solution (solid content 75%), and a second mixture is mixed to obtain a high-efficiency closed-cell high-stability slurry.

[0127] Example 2: In preparing core-shell microparticles, the first and second core-shell microparticles were prepared using a mixture of materials;

[0128] The first core-shell microparticle core was composed of 44g boron nitride (thermal conductive agent) + 11g ethoxy-pentafluorocyclotriphosphazene (flame retardant), and the shell was composed of 270g Fischer-Tropsch wax solution (thermal accelerator, solid content 40%) + 77.1g oxidized polyethylene wax solution (thermal accelerator, solid content 35%). The second core-shell microparticle core was composed of 10g monocrystalline thermally conductive alumina (thermal conductive agent) + 40g aluminum hypophosphite (flame retardant), and the shell was composed of 360g stearamide solution (thermal accelerator, solid content 30%) + 108g erucamide solution (thermal accelerator, solid content 25%). The total mass of the core-shell microparticles was the same as in Example 1. The types and amounts of other additives and all process parameters were exactly the same as in Example 1, without any adjustments.

[0129] Example 3: When preparing core-shell microparticles, the ratio of the total mass of the first core-shell microparticle and the second core-shell microparticle thermosensitive agent to the total mass of the thermosensitive accelerator was set to 4:6;

[0130] The first core-shell microparticle core was composed of 45g boron nitride (thermal conductive agent) + 15g ethoxy-pentafluorocyclotriphosphazene (flame retardant), and the shell was composed of 250g Fischer-Tropsch wax solution (thermal accelerator, solid content 40%) + 76.29g oxidized polyethylene wax solution (thermal accelerator, solid content 35%). The second core-shell microparticle core was composed of 10g monocrystalline thermally conductive alumina (thermal conductive agent) + 40g aluminum hypophosphite (flame retardant), and the shell was composed of 311g stearamide solution (thermal accelerator, solid content 30%) + 320g erucamide solution (thermal accelerator, solid content 25%). The total mass of the core-shell microparticles was the same as in Example 1. The types and amounts of other additives and all process parameters were exactly the same as in Example 1, without any adjustments.

[0131] Example 4: When preparing core-shell microparticles, the ratio of the total mass of the first core-shell microparticle and the second core-shell microparticle thermosensitive agent to the total mass of the thermosensitive accelerator was set to 3:7;

[0132] The first core-shell microparticle core was composed of 45g boron nitride (thermal conductive agent) + 15g ethoxy-pentafluorocyclotriphosphazene (flame retardant), and the shell was composed of 287.5g Fischer-Tropsch wax solution (thermal accelerator, 40% solid content) + 71.43g oxidized polyethylene wax solution (thermal accelerator, 35% solid content). The second core-shell microparticle core was composed of 10g monocrystalline thermally conductive alumina (thermal conductive agent) + 40g aluminum hypophosphite (flame retardant), and the shell was composed of 191.67g stearamide solution (thermal accelerator, 30% solid content) + 310g erucamide solution (thermal accelerator, 25% solid content). The total mass of the core-shell microparticles was the same as in Example 1. The types and amounts of other additives and all process parameters were exactly the same as in Example 1, without any adjustments.

[0133] Example 5:

[0134] The dispersing agent was replaced with 3g sodium polyacrylate solution (40% solid content) and 40.4g sodium polystyrene sulfonate solution (25% solid content). The preparation process and dosage of the first and second core-shell microparticles, the types and dosages of other additives, and all mixing process parameters were completely consistent with those in Example 1 without any adjustments.

[0135] Example 6:

[0136] The heat stabilizer was replaced with 107.5g of polyacrylate solution (20% solid content) and 104.17g of polyvinyl alcohol solution (12% solid content). The preparation process and dosage of the first and second core-shell microparticles, the types and dosages of other additives, and all mixing process parameters were completely consistent with those in Example 1, without any adjustments.

[0137] Example 7:

[0138] The wetting agent was replaced with 0.81g alkylphenol polyoxyethylene ether solution (99% solid content). The preparation process and dosage of the first and second core-shell microparticles, the types and dosages of other additives, and all mixing process parameters were completely consistent with those in Example 1, without any adjustments.

[0139] The following are comparative examples used for comparison experiments with the embodiments:

[0140] Comparative Example 1: Replace the second core-shell particle with an equal mass of the first core-shell particle;

[0141] In Example 1, the 139.5g of second core-shell microparticles in S300 were completely replaced with an equal mass of first core-shell microparticles. Specifically, the S300 feed composition was adjusted to: 207.3g water, 199.5g first core-shell microparticles (originally 60g first core-shell microparticles + 139.5g first core-shell microparticles), and dispersing agent: 100g sodium carboxymethyl cellulose solution (2% solid content) + 27g acrylic polymer solution (40% solid content). All other preparation processes remained the same as in Example 1.

[0142] Comparative Example 2: The first core-shell particles were replaced with second core-shell particles of equal mass;

[0143] In Example 1, S300, all 60g of the first core-shell microparticles were replaced with an equal mass of the second core-shell microparticles. That is, the feed of S300 was adjusted to: 207.3g water, 199.5g of the second core-shell microparticles (original 60g of the first core-shell microparticles + 139.5g of the second core-shell microparticles), and dispersing aids: 100g sodium carboxymethyl cellulose solution (solid content 2%) + 27g acrylic polymer solution (solid content 40%). The rest of the preparation process was the same as in Example 1.

[0144] Comparative Example 3: The first core-shell microparticle core contains only flame retardant (no thermal conductive agent).

[0145] When preparing the first core-shell microparticles, the core was replaced with 50g of ethoxy-pentafluorocyclotriphosphazene (pure flame retardant), and the shell was still made of 416.7g of palm wax solution (30% solid content) from Example 1; the rest of the preparation process was the same as in Example 1.

[0146] Comparative Example 4: First core-shell microparticle core thermal conductive agent: flame retardant = 3:7 (thermal conductive agent content < flame retardant);

[0147] When preparing the first core-shell microparticles, the core was set as 15g of single-crystal thermally conductive alumina (thermal conductive agent) + 35g of ethoxy-pentafluorocyclotriphosphazene (flame retardant), with a mass ratio of thermal conductive agent to flame retardant of 3:7. The total mass of the core was 50g, consistent with Example 1. The shell was still made of 416.7g of palm wax solution (solid content 30%), and the rest of the preparation process was consistent with Example 1.

[0148] Comparative Example 5: The flame retardant content in the second core-shell microparticle core was less than the thermal conductive agent content;

[0149] This comparative example only adjusts the core ratio of the second core-shell microparticles to make the flame retardant content lower than that of the thermal conductive agent. The rest of the preparation process is the same as in Example 1, with the specific adjustments as follows:

[0150] The second core-shell microparticle core is composed of 40g of single-crystal thermally conductive alumina (thermal conductive agent) + 10g of aluminum hypophosphite (flame retardant), with a flame retardant to thermal conductive agent mass ratio of 1:4 (flame retardant content < thermal conductive agent). The total core mass is 50g, consistent with Example 1. The shell is still made of 312.5g of polyethylene wax solution (solid content 40%).

[0151] Comparative Example 6: The content of the heat-sensitive main agent in the shell of the second core-shell microparticle is less than the content of the heat-sensitive accelerator;

[0152] This comparative example only adjusts the shell ratio of the second core-shell microparticles to make the content of the thermosensitive main agent lower than that of the thermosensitive accelerator. The rest of the preparation process is the same as in Example 1, with the specific adjustments as follows:

[0153] The second core-shell microparticle shell is composed of 259.3g Fischer-Tropsch wax solution (thermosensitive accelerator, solid content 40%) + 71g stearamide solution (thermosensitive main agent, solid content 30%), with a mass ratio of thermosensitive main agent to thermosensitive accelerator of 1:4.87 (main agent content < accelerator). The total shell mass is 125g, consistent with Example 1. The core is still made of 30g polyphosphazene powder.

[0154] Comparative Example 7: The mass ratio of the heat-sensitive main agent to the heat-sensitive accelerator exceeded the range of 1:9 to 9:1;

[0155] This comparative example only adjusts the shell ratio of the first and second core-shell microparticles to make the mass ratio of the heat sensitizer to the heat sensitizer accelerator 1:10 (lower than the lower limit of 1:9). The rest of the preparation process is the same as in Example 1, with the following specific adjustments:

[0156] First core-shell microparticle shell: set as 284.1g Fischer-Tropsch wax solution (thermally sensitive accelerator, solid content 40%) + 32.5g oxidized polyethylene wax solution (thermally sensitive main agent, solid content 35%), the total shell mass is 125g, consistent with Example 1;

[0157] The second core-shell microparticle shell is composed of 454.55g erucamide solution (thermally sensitive accelerator, solid content 25%) + 37.88g stearamide solution (thermally sensitive main agent, solid content 30%), with a total shell mass of 125g, consistent with Example 1.

[0158] The slurries prepared in the above embodiments and comparative examples were used to prepare lithium-ion batteries according to the following method, which includes the following steps:

[0159] S100: The high-efficiency closed-cell high-stability slurry prepared in Example 1 above is coated onto the first side of the 7µm polyethylene diaphragm by means of a micro-concave roller. After drying, the high-efficiency closed-cell high-stability slurry is coated onto the second side of the polyethylene diaphragm opposite to the first side. After drying and winding, a safety composite diaphragm A1 with a high-efficiency closed-cell high-stability coating is obtained.

[0160] S200: The first side of the safety composite separator A1 is in contact with the positive electrode of the battery (lithium iron phosphate), and the second side of the safety composite separator A1 is in contact with the negative electrode of the battery (graphite). The cells are then prepared by winding or stacking processes.

[0161] S300: After the cells are assembled, baked at 85°C, injected with electrolyte, and subjected to formation and capacity testing, a lithium-ion battery N1 with a high-efficiency closed-pore, high-stability coating is obtained.

[0162] Using the high-efficiency closed-cell high-stability slurry prepared in Example 2 above, lithium-ion batteries were prepared by the above method to obtain a safe composite separator A2 and a lithium-ion battery N2.

[0163] Using the high-efficiency closed-cell high-stability slurry prepared in Example 3 above, lithium-ion batteries were prepared by the above method to obtain a safe composite separator A3 and a lithium-ion battery N3.

[0164] Using the high-efficiency closed-cell high-stability slurry prepared in Example 4 above, lithium-ion batteries were prepared by the above method to obtain a safe composite separator A4 and a lithium-ion battery N4.

[0165] Using the high-efficiency closed-cell high-stability slurry prepared in Example 5 above, lithium-ion batteries were prepared by the above method to obtain a safe composite separator A5 and a lithium-ion battery N5.

[0166] Using the high-efficiency closed-cell high-stability slurry prepared in Example 6 above, lithium-ion batteries were prepared by the above method to obtain a safe composite separator A6 and a lithium-ion battery N6.

[0167] Using the high-efficiency closed-cell high-stability slurry prepared in Example 7 above, lithium-ion batteries were prepared by the above method to obtain a safe composite separator A7 and a lithium-ion battery N7.

[0168] Using the slurry prepared in Comparative Example 1 above, a lithium-ion battery was prepared by the above method to obtain a separator DA1 and a lithium-ion battery DN1.

[0169] Using the slurry prepared in Comparative Example 2 above, a lithium-ion battery was prepared by the above method to obtain a separator DA2 and a lithium-ion battery DN2;

[0170] Using the slurry prepared in Comparative Example 3 above, a lithium-ion battery was prepared by the above method to obtain a separator DA3 and a lithium-ion battery DN3.

[0171] Using the slurry prepared in Comparative Example 4 above, lithium-ion batteries were prepared by the above method to obtain separator DA4 and lithium-ion battery DN4;

[0172] Using the slurry prepared in Comparative Example 5 above, lithium-ion batteries were prepared by the above method to obtain separator DA5 and lithium-ion battery DN5;

[0173] Using the slurry prepared in Comparative Example 6 above, a lithium-ion battery was prepared by the above method to obtain a separator DA6 and a lithium-ion battery DN6.

[0174] Using the slurry prepared in Comparative Example 7 above, lithium-ion batteries were prepared by the above method to obtain separator DA7 and lithium-ion battery DN7;

[0175] A lithium battery DN8 was prepared by using a 7µm base film 4 as the separator for the lithium battery, which is the separator DA8.

[0176] The separators and lithium-ion batteries prepared in the above embodiments and the separators and lithium-ion batteries in the comparative examples were tested, and the corresponding test data and results were obtained. The specific tests are as follows:

[0177] (1) Air permeability: The air permeability was obtained by testing using a Gurley air permeability meter according to the method specified in 6.5.4 of GB / T36363-2018.

[0178] (2) Limiting Oxygen Index (LOI): The LOI value of the safety composite diaphragm is tested using a limiting oxygen index meter to evaluate its flame retardant performance. The test method is as follows: the sample is vertically fixed in a transparent combustion chamber with a continuous flow of nitrogen-oxygen mixture. The minimum oxygen concentration (volume fraction) when the combustion time is greater than 180s or the combustion distance is greater than 50mm is the measured LOI value.

[0179] (3) Thermal conductivity: measured by HotDisk TPS2500S thermal constant analyzer.

[0180] (4) Melting enthalpy (ΔH) test: The ΔH of the safety composite membrane is tested by differential scanning calorimetry (DSC).

[0181] (5) Electrochemical stability: Linear sweep voltammetry (LSV) tests were conducted using an electrochemical workstation to evaluate the electrochemical stability of the safety composite membrane in the electrolyte.

[0182] (6) High-temperature pore-closure effect test: Real-time impedance test was conducted using a simulated battery and an electrochemical workstation to evaluate the high-temperature pore-closure effect of the membrane.

[0183] (7) Overcharge test: The test shall be conducted in accordance with the method specified in Appendix A Test Method A.2.12 of GB / T36276-2018. The lithium-ion battery shall be placed in a stainless steel fixture and clamped. The test shall be conducted to observe whether the lithium-ion battery swells, opens the valve, overflows, smokes, catches fire or explodes.

[0184] (8) Short circuit test: The test shall be conducted in accordance with the method specified in Appendix A Test Method A.2.14 of GB / T36276-2018. The lithium-ion battery shall be placed in a stainless steel fixture and clamped. The test shall be conducted to observe whether the lithium-ion battery swells, opens the valve, overflows, smokes, catches fire or explodes.

[0185] (9) Heating test: The test shall be conducted in accordance with the method specified in Appendix A Test Method A.2.18 of GB / T36276-2018. The lithium-ion battery shall be placed in a stainless steel fixture and clamped. The test shall be conducted to observe whether the lithium-ion battery swells, opens the valve, overflows, smokes, catches fire or explodes.

[0186] (10) Thermal runaway test: The test shall be conducted in accordance with the method specified in Appendix A Test Method A.2.19 of GB / T36276-2018. The lithium-ion battery shall be placed in a stainless steel fixture and clamped. The test shall be conducted to observe whether the lithium-ion battery swells, opens the valve, overflows, smokes, catches fire or explodes.

[0187] (11) Needle penetration test: The test is conducted in accordance with the IEC62133 standard. The battery cell is placed in the needle penetration test machine and the needle penetration test is performed. Test conditions: 6mm steel needle. Observe whether the lithium-ion battery opens the valve, overflows, smokes, catches fire or explodes.

[0188] (12) DC internal resistance (DCR) test: Let the battery with 100% SOC stand for 30 minutes to eliminate polarization effect; use DC internal resistance test equipment to apply a DC pulse between the positive and negative terminals for 10ms, record the voltage drop ΔV, and calculate the DCR value under different SOC (0-100%).

[0189] (13) Cyclic test: The test shall be conducted in accordance with the method specified in Appendix A, Test Method A.2.11 of GB / T36276-2018.

[0190] The above test methods were used to test each embodiment and each comparative example 1, and the obtained diaphragm performance test data included: air permeability, LOI value, thermal conductivity, and electrochemical stability. The test performance is shown in Table 1:

[0191] Table 1: Comparison data for Test 1

[0192]

[0193] Comparative analysis of the data in Table 1 reveals that the safety composite membranes A1-A7 in the embodiments, relying on the differentiated ratio of the first and second core-shell microparticles and the precise control of the thermosensitive, thermally conductive, and flame-retardant systems, ensure ion conduction efficiency. Simultaneously, their thermal conductivity is within a highly efficient and balanced range, their limiting oxygen index reaches 38-40%, and their melting enthalpy and activation energy are significantly lower than those of the other groups in the comparative examples, achieving an optimal balance between thermal conductivity, flame retardancy, and thermal response sensitivity. In contrast, the comparative membranes DA1-DA7, due to issues such as excessive amounts of a single core-shell microparticle, imbalanced ratios of various functional systems, and out-of-range ratios of thermosensitive components, exhibit significant deterioration in permeability, polarized thermal conductivity, insufficient flame retardancy, and a sharp increase in melting enthalpy and activation energy, resulting in a substantial reduction in thermal response efficiency. The blank membrane DA8 lacks a functional coating, fails to meet all safety-related indicators, and lacks active safety protection capabilities. This fully demonstrates that the formulation design of this application can balance battery electrochemical performance and safety protection performance, while schemes deviating from this design struggle to achieve performance balance.

[0194] The aforementioned test methods were used to test each embodiment and each comparative example. Real-time impedance testing was conducted using simulated batteries and an electrochemical workstation to evaluate the high-temperature blocking effect of the separator: the simulated battery was placed in a temperature chamber, heated to 110°C, and held for 10 minutes. The change in the AC impedance of the battery during the heating process was continuously monitored. The test results are shown in Table 2.

[0195] Table 2: Comparison data for Test 2

[0196]

[0197] Table 2 shows the high-temperature pore-closure performance test data. The coatings of the safety composite separators A1-A7 in the examples exhibit a sharp increase in impedance at high temperatures, with a pore-closure trigger temperature as low as 89-92℃ and impedance stabilization requiring only 40-48 seconds, achieving a rapid and efficient pore-closure response. In contrast, the coatings of the comparative separators DA1-DA7 show a slow increase in impedance, a higher pore-closure trigger temperature (94-99℃), and the impedance change does not reach a stable state during the test, resulting in a severely delayed pore-closure response. The blank control DA8, a commonly used blank separator, shows no impedance change and completely lacks pore-closure capability at 110℃, fully demonstrating that the formulation of this application enables the coating to achieve efficient pore closure, while deviations from this design result in significantly degraded pore-closure performance. The above results indicate that the safety composite separator prepared from the high-efficiency pore-closure and high-stability slurry provided in this application achieves rapid and synergistic thermal response and multiple safety protections at high temperatures, and also exhibits excellent air permeability, making it suitable for lithium-ion batteries.

[0198] Reference Figure 2 , Figure 2 The solid line representing Example 1 has the smallest peak area, the lowest onset temperature (approximately 90°C), and the flattest and sharpest peak shape. This is consistent with the fact that Example 1 in Table 1 has a melting enthalpy of only 2.5 J. g - The low-energy rapid melting characteristics of ¹ directly correspond to and are consistent with its efficient closed-cell performance of 92℃ trigger temperature and only 48s impedance stabilization time in Table 2, confirming the high efficiency of its thermosensitive system co-design. Meanwhile, the peak areas of the dashed line representing Comparative Example 1 and the dotted line representing Comparative Example 2 increase sequentially, the starting temperature shifts later (approximately 95℃ in Comparative Example 1 and approximately 98℃ in Comparative Example 2), and the peak shape becomes wider, corresponding to the melting enthalpy of 31.6J in Comparative Example 1 in Table 1. g - ¹, Comparative Example 2: enthalpy of fusion 58.9 J g - The high energy demand and hysteresis response of ¹ are also completely consistent with the inefficient pore-closure results of Comparative Examples 1 and 2 in Table 2, where the impedance did not reach steady state. This directly reflects that the design of “synergistic ratio of thermosensitive main agent + accelerator” and “synergistic ratio of first and second core-shell particles” in this application can significantly reduce the melting energy barrier and achieve rapid pore closure. In contrast, the comparative examples that deviate from this design have the defects of low melting efficiency and sluggish thermal response.

[0199] Finally, the aforementioned test methods were used to test each embodiment and each comparative example. The obtained lithium-ion batteries were subjected to performance tests, including overcharge test, short circuit test, heating test, thermal runaway test and electrical performance test. Then, the obtained lithium-ion batteries were subjected to nail penetration test according to IEC62133 standard. The test results are shown in Table 3.

[0200] Table 3: Comparison data for Test 3

[0201]

[0202]

[0203]

[0204] Table 3 shows the results of the full-scale battery safety tests. Examples N1-N7 did not exhibit expansion, valve opening, leakage, smoke, or fire in overcharge, short circuit, heating, needle penetration, and thermal runaway tests, demonstrating comprehensive safety protection capabilities. Comparative examples DN1-DN7 exhibited valve opening, leakage, and continuous heavy smoke in all tests, and even fire, indicating complete failure of safety protection. The blank control DN8 battery not only experienced valve opening and leakage but also fire, posing a serious safety hazard. This strongly demonstrates that the formulation design of this application can provide a reliable safety barrier for the battery, while deviations from this design cannot guarantee battery safety. The above results show that the high-efficiency closed-cell high-stability slurry and its preparation method, lithium-ion batteries, and electrical equipment provided by this invention, when the battery malfunctions, reduce the melting phase transition enthalpy through a synergistic system of "thermosensitive main agent + thermosensitive accelerator + thermal conductive agent," transforming a passive response into an active synergy, achieving efficient pore closing. Simultaneously, the flame retardant released by the heat stabilizer provides a continuous safety barrier after pore closing, improving the inherent safety of the battery.

[0205] This invention is in Figure 3 Exemplary examples are provided for the DCR (Discharge Rate of Lithium-ion Batteries) of Embodiment 1 and Comparative Example 8 at different SOCs (0-100%). Figure 3 ) curve and discharge capacity retention curve of battery cycle test at room temperature ( Figure 4 Based on the safety test results in Table 3, Figure 3 , Figure 4 Analysis shows that the battery in Example 1 of Table 3 showed no abnormalities such as expansion, valve opening, or fire in all tests including overcharge, short circuit, heating, nail penetration, and thermal runaway, demonstrating excellent safety protection capabilities; while Figure 3 The curve in Example 1 shows that its DC internal resistance remains stable at 0.3~0.4mΩ within the 0~80% normal charge range, with only a slight increase at high SOC. Figure 4 The curve of Example 1 shows that its capacity retention rate is still about 98.4% after 800 cycles and the decay is gradual, which confirms that the coating of this application can achieve multiple safety protections without sacrificing the low internal resistance and long cycle performance of the battery. In contrast, the battery of Comparative Example 8, as shown in Table 3, showed serious safety hazards such as valve opening, leakage and even fire in all safety tests. Figure 3 The curve in Comparative Example 8 shows that its internal resistance is higher across the entire SOC range, reaching 0.71 mΩ at 100% SOC. Figure 4The curve in Comparative Example 8 shows that its capacity retention rate is only about 92.2% after 800 cycles and the decay is faster. This intuitively reflects that the blank scheme without functional coating cannot guarantee battery safety or maintain stable electrochemical performance.

[0206] In summary, lithium-ion batteries prepared using the aforementioned high-efficiency closed-cell high-stability slurry possess all the beneficial effects of high-efficiency closed-cell high-stability slurry, greatly improving the safety of lithium-ion batteries in use.

[0207] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0208] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A high-efficiency closed-cell, highly stable slurry, characterized in that, include: The core-shell microspheres comprise first core-shell microparticles and second core-shell microparticles. The core of the first core-shell microparticle is a mixture of a thermally conductive agent and a flame retardant, or any one or more of the thermally conductive agents, with the thermally conductive agent content exceeding the flame retardant content. The shell of the first core-shell microparticle is a mixture of a heat-sensitive accelerator and a heat-sensitive main agent, or any one or more of the heat-sensitive accelerators, with the heat-sensitive accelerator content exceeding the heat-sensitive main agent content. The core of the second core-shell microparticle is a mixture of a thermally conductive agent and a flame retardant, or any one or more of the flame retardants, with the flame retardant content exceeding the thermally conductive agent content. The shell of the second core-shell microparticle is a mixture of a heat-sensitive accelerator and a heat-sensitive main agent, or any one or more of the heat-sensitive main agent, with the heat-sensitive main agent content exceeding the heat-sensitive accelerator content. The mass ratio of the heat-sensitive main agent to the heat-sensitive accelerator in the core-shell microspheres is 1:9 to 9:

1. Heat stabilizers; Auxiliary agents, including wetting agents and dispersing agents; water; The core-shell microspheres contain 25-40 wt%, the heat stabilizer contains 1-5 wt%, the auxiliary agents contain 0.5-5 wt%, and the water contains 50-73.5 wt%. The heat-sensitive accelerator is at least one of Fischer-Tropsch wax, palm wax, hydrogenated castor oil, microcrystalline wax, paraffin wax, lignite wax, erucamide, candelilla wax, stearic acid, stearyl glycyrrhetinic acid ester, oleamide, ethylene-vinyl acetate wax, glyceryl stearate, stearyl alcohol, polycaprolactone, and hydrogenated palm oil. The thermosensitive main agent is selected from at least one of stearamide, ethylene-vinyl acetate copolymer, hydrogenated petroleum resin, polyethylene wax, polyacrylate, palmitamide, copolyester, oxidized polyethylene wax, lauramide, myristamide, behenamide, eicosamide, montan wax oxidized derivative, and ethylene acrylic acid copolymer. The thermally conductive agent is at least one of the following: monocrystalline thermally conductive alumina, zirconium oxide, polycrystalline silicon nitride, aluminum nitride, zinc oxide, magnesium oxide, silicon dioxide, molybdenum oxide, boron nitride, graphene, carbon nanotubes, and carbon fibers. The flame retardant is at least one of polyphosphazene, ethoxy-pentafluorocyclotriphosphazene, aluminum hypophosphite, diethyl ethyl phosphonate, dimethoxymethyl phosphate, decabromodiphenyl ethane, triphenyl phosphate, triethyl phosphate, polyphosphate, antimony trioxide, trimethyl phosphate, and trimethyl phosphite.

2. The high-efficiency closed-cell high-stability slurry according to claim 1, characterized in that, The melting point of the thermosensitive main agent is greater than that of the thermosensitive accelerator, and the difference between the melting point of the thermosensitive main agent and the melting point of the thermosensitive accelerator is 5~20℃; the particle size of the core-shell microspheres is 0.3~6μm, the shell thickness of the first core-shell microspheres accounts for 10%~25% of the radius of the first core-shell microspheres, and the shell thickness of the second core-shell microspheres accounts for 10%~25% of the radius of the second core-shell microspheres.

3. The high-efficiency closed-cell high-stability slurry according to claim 1, characterized in that, The heat stabilizer includes at least one of polyacrylamide, polyacrylate, polyphthalamide, polyacrylonitrile, poly(p-phenylene terephthalamide), polyvinyl alcohol, acrylic acid and derivatives of multi-component copolymers.

4. The high-efficiency closed-cell high-stability slurry according to claim 1, characterized in that, The wetting aid comprises at least one of sodium diisooctyl succinate sulfonate, alkylphenol polyoxyethylene ether, aliphatic polyether, polyethylene glycol, sodium alginate, hydroxyethyl cellulose, polyether ester, and polyester. The dispersing agent is selected from at least one of the following: acrylic block copolymer, sodium carboxymethyl cellulose, acrylic polymer, sodium polyacrylate, sodium polycarboxylate, ammonium polyacrylate, maleic anhydride copolymer, sodium polystyrene sulfonate, polyacrylate copolymer, sodium lignosulfonate, polyurethane, and polyacrylic acid.

5. A method for preparing a high-efficiency closed-cell highly stable slurry, used to prepare the high-efficiency closed-cell highly stable slurry as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S100: Preparation of the first core-shell microparticles; S200: Preparation of second core-shell microparticles; S300: A first mixture is obtained by initially mixing water, first core-shell microparticles, second core-shell microparticles, and dispersing agent; S400: The heat stabilizer is mixed with the first mixture to obtain the second mixture; S500: Water, wetting agent, and second mixture are mixed to obtain a high-efficiency closed-cell, highly stable slurry.

6. The method for preparing the high-efficiency closed-cell, high-stability slurry according to claim 5, characterized in that, Step S100 includes the following steps: S101: Add the first core-shell component to a planetary mixer. While stirring, add the first core-shell component in batches and slowly to obtain the first premixed liquid. The stirring speed is 400~800 rpm and the stirring time is 20~70 min. S102: The first premixed liquid is transferred to a high-speed homogenizer for homogenization and dispersion to obtain the second premixed liquid. The dispersion speed is 1000~2000 rpm and the dispersion time is 10~20 min. S103: Transfer the second premix to a magnetic stirrer, add water and stir at low speed to obtain the first mixture. The stirring speed is 50~300 rpm. S104: The first mixture is filtered and vacuum degassed to obtain the first spray-drying feed liquid; S105: The first spray drying feed liquid is transferred to a spray dryer for spray drying to obtain the first core-shell powder. The inlet temperature of the spray dryer is 80~110℃, the outlet temperature is 45~65℃, the feed rate is 6~10mL / min, the atomization pressure is 1.5~2.5bar, and the drying medium is nitrogen. S106: The dried first core-shell powder is collected using a cyclone separator and then heat-treated in a vacuum drying oven to obtain the first core-shell microparticles, wherein the heat treatment temperature is 40~60℃ and the time is 1~3.5h.

7. The method for preparing the high-efficiency closed-cell high-stability slurry according to claim 5, characterized in that, Step S200 includes the following steps: S201: Add the second core-shell component to the planetary mixer. While stirring, add the second core-shell component in batches and slowly to obtain the third premix. The stirring speed is 300~800 rpm and the stirring time is 30~90 min. S202: The third premixed liquid is transferred to a high-speed homogenizer for homogenization and dispersion to obtain the fourth premixed liquid. The dispersion speed is 1000~2000 rpm and the dispersion time is 10~20 min. S203: Transfer the fourth premix to a magnetic stirrer, add water and stir at low speed to obtain the second mixture. The stirring speed is 50~300 rpm. S204: The second mixture is filtered and vacuum degassed to obtain the second spray-drying feed liquid; S205: The second spray drying feed liquid is transferred to a spray dryer for spray drying to obtain the second core-shell powder. The inlet temperature of the spray dryer is 90~120℃, the outlet temperature is 55~75℃, the feed rate is 5~8mL / min, the atomization pressure is 1.5~3.0bar, and the drying medium is nitrogen. S206: The dried first core-shell powder is collected using a cyclone separator and then heat-treated in a vacuum drying oven to obtain heat-sensitive agent core-shell microparticles, wherein the heat treatment temperature is 45~70℃ and the time is 1~2h.

8. A method for preparing a lithium-ion battery, characterized in that, Includes the following steps: S100: The high-efficiency closed-cell high-stability slurry as described in any one of claims 1 to 2 is coated on the first side of the base film, and then the high-efficiency closed-cell high-stability slurry is coated on the second side of the base film opposite to the first side to obtain a safety composite membrane with high-efficiency closed-cell high-stability slurry. S200: The first side of the safety composite separator is in contact with the positive electrode of the battery, and the second side of the safety composite separator is in contact with the negative electrode of the battery. The cells are then manufactured by winding or stacking processes. S300: Assemble the cells to obtain a lithium-ion battery with a high-efficiency closed-cell, high-stability slurry.

9. An electrical appliance, characterized in that, The electrical device uses a lithium-ion battery prepared by the method for preparing a lithium-ion battery as described in claim 8.

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