A semi-solid separator, electrode assembly, and lithium-ion battery with low thermal pressure transfer function.

Abstract

This invention belongs to the field of lithium-ion battery technology, specifically relating to a semi-solid separator, electrode assembly, and lithium-ion battery with low-temperature thermal pressure transfer capability. The semi-solid separator includes a base film and a semi-solid coating disposed on the surface of the base film. The semi-solid coating includes a semi-solid coating body and an adhesive layer disposed on the surface of the semi-solid coating body. The adhesive layer includes organic particles; the organic particles include a core-shell polymer, comprising a shell layer and a core layer. The shell layer is composed of soft monomer components with a low glass transition temperature, configured to soften and provide adhesion within the thermal pressure temperature range. The core layer is composed of hard monomer components with a high glass transition temperature, configured to soften and provide transfer functionality within the baking temperature range. Through the staged bonding characteristics of the core-shell structured organic particles, electrode assembly shaping can be achieved at lower thermal pressure parameters, and coating transfer can be completed during subsequent baking, thereby reducing electrode damage.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a semi-solid separator, electrode assembly, and lithium-ion battery with low thermal pressure transfer function. Background Technology

[0002] With the accelerated global energy structure transformation and the rapid development and widespread application of new energy technologies, lithium batteries have become a core energy carrier in fields such as electric vehicles, renewable energy storage systems, and portable electronic devices. However, frequent lithium battery safety incidents seriously affect safety in use and have become a key bottleneck restricting the industry's development.

[0003] Battery separators play a crucial role as an "invisible defense" in battery safety. Through physical isolation mechanisms, they prevent short circuits and thermal runaway at the source, serving as the first line of defense against internal short circuits and thermal safety issues within the battery cell. Despite continuous advancements in separator technology, existing types still have some shortcomings. While current separator technology mitigates safety risks to some extent, it remains inadequate under extreme operating conditions, requiring further improvement through material innovation, process optimization, and rigorous quality testing.

[0004] Building upon traditional separators, the industry is also focusing on developing semi-solid separators to further improve the safety performance of battery cells. Through a solid-liquid hybrid electrolyte design, semi-solid separators retain some of the advantages of liquid battery technology while significantly improving safety, cycle life, and adaptability to extreme environments. This represents a crucial direction for the transition of battery technology from liquid to all-solid state. The application of semi-solid separators involves coating the separator surface with a composite semi-solid coating. While maintaining the separator's heat resistance and electrode bonding capabilities, the composite semi-solid coating can be completely transferred to the electrode surface through a hot-pressing process. Even with the shrinkage and rupture of the polyolefin base film, it continues to function as an separator between the positive and negative electrodes, achieving an electrolyte transfer rate of over 95%. However, in related technologies, to ensure the complete transfer and firm adhesion of the semi-solid coating to the positive electrode, high temperature and pressure parameters are often required during the hot-pressing process. However, these high hot-pressing parameters can easily damage the electrode structure, such as causing the detachment of the negative electrode active material, and may lead to changes in the internal pore structure of the electrode assembly, thus adversely affecting the subsequent electrolyte wetting effect.

[0005] Therefore, how to significantly reduce the temperature and pressure parameters required for the hot pressing process while ensuring that the semi-solid coating can be completely transferred in the end, so as to avoid damage to the electrode and ensure good electrolyte wettability, has become a specific technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] In view of this, the present invention aims to at least partially solve one of the technical problems in the related art. To this end, the present invention provides a semi-solid transfer coating separator that can achieve bonding with the electrode at a lower temperature, meeting the electrode assembly shaping requirements. After high-temperature baking of the battery cell, the adhesion to the electrode can be further improved, enabling the semi-solid coating to be transferred to the surface of the positive electrode, thus solving the negative impact of the large hot-pressing parameters of conventional semi-solid transfer separators on battery cell performance.

[0007] To solve the above-mentioned technical problems, the present invention is implemented as follows: According to one aspect of the present invention, a semi-solid membrane with low thermal pressure transfer function is provided, the semi-solid membrane comprising a base membrane and a semi-solid coating disposed on the surface of the base membrane; The semi-solid coating includes a semi-solid coating body and an adhesive layer disposed on the surface of the semi-solid coating body; The adhesive layer includes organic adhesive particles; The organic colloidal particles comprise a core-shell polymer, and the organic colloidal particles comprise a shell layer and a core layer. The shell is composed of a soft monomer component with a low glass transition temperature and is configured to soften and provide adhesion in the hot-pressing temperature range. The core layer is composed of a hard monomer component with a high glass transition temperature and is configured to soften within the baking temperature range and provide transfer functionality.

[0008] In some of these embodiments, the hard monomer includes at least one of styrene, methyl methacrylate, methyl acrylate, methylstyrene, acrylonitrile, and acrylamide.

[0009] In some embodiments, the soft monomer includes at least one of ethyl acrylate, butyl acrylate, and isooctyl acrylate.

[0010] In some of these embodiments, the glass transition temperature of the shell is -40°C to 25°C.

[0011] In some embodiments, the glass transition temperature of the core layer is 70°C to 105°C.

[0012] In some embodiments, the particle size of the organic particles is 0.3 μm to 1.0 μm.

[0013] In some embodiments, the coating thickness of the adhesive layer is 1 μm to 2 μm.

[0014] In some of these embodiments, the adhesive layer covers 70% to 90% of the semi-solid coating substrate.

[0015] In some embodiments, the adhesive layer further comprises 2 to 7 parts of binder, 0.1 to 0.5 parts of dispersant, and 0.1 to 0.6 parts of wetting agent, based on 100 parts of total organic particles.

[0016] In some embodiments, the adhesive includes at least one of polyacrylic acid compounds and polyacrylate compounds.

[0017] In some of these embodiments, the adhesive includes at least one of polymethyl methacrylate, polymethyl methacrylate, polyethyl methacrylate, or polyethyl methacrylate.

[0018] In some embodiments, the dispersant comprises a carboxylate compound.

[0019] In some embodiments, the dispersant includes at least one of sodium carboxylate and carboxylic amine.

[0020] In some embodiments, the wetting agent includes at least one of polyethylene glycol, polydimethylsiloxane, and polyoxyethylene ether.

[0021] In some embodiments, the semi-solid coating body comprises a semi-solid ion-conducting material.

[0022] In some of these embodiments, the semi-solid coating substrate comprises lithium titanium aluminum phosphate and / or lithium lanthanum zirconium oxide.

[0023] In some embodiments, the semi-solid coating body further includes one or more combinations of inorganic ceramic materials, rod-shaped organic nanofiber materials, rod-shaped PI fiber materials, and aqueous aramid particles.

[0024] In some embodiments, the inorganic ceramic material includes at least one of alumina, boehmite, magnesium hydroxide, barium sulfate, and silicon dioxide.

[0025] In some embodiments, the rod-shaped organic nanofiber material comprises rod-shaped organic nanofiber material formed by carboxylation and grafting of natural cellulose.

[0026] In some embodiments, the base film includes at least one of polyethylene (PE), polypropylene (PP), polyimide (PI), and aramid.

[0027] In some of these embodiments, the thickness of the base film is 3 μm to 25 μm.

[0028] In some embodiments, X is the ratio of the shell to the core thickness of the organic colloidal particle; mg / m 2The coating density of the adhesive layer on the base film; T℃ is the hot-pressing temperature; P MPa is the hot-pressing pressure; The hot pressing process satisfies the following relationships: Relationship 1 and Relationship 2: Relationship 1: T≥25+35(1- ); Relationship 2: P≥0.3+1.8(1- ); Where 0.3≤X≤1.0; 0.3≤M≤1.0.

[0029] To determine the minimum necessary and effective hot-pressing process window for particles with different structural parameters, ensuring reliable electrode assembly shaping and guiding mass production, this invention establishes the aforementioned quantitative relationship model. The physical meaning of this quantitative relationship lies in its reflection of the compensation relationship between hot-pressing process parameters and key structural parameters of the particles. A higher shell-to-core thickness ratio (X) means more shell material per unit particle that can soften at hot-pressing temperatures, providing stronger initial bonding ability, and therefore a lower required hot-pressing temperature (T) compensation value. A higher coating areal density (M) means more effective bonding points per unit area, stronger overall bonding ability, and therefore a lower required hot-pressing pressure (P) compensation value. Conversely, when the X value is small (relatively thin shell) or the M value is small (small coating amount), the initial bonding ability is weaker, requiring an appropriate increase in hot-pressing temperature or pressure to compensate and ensure reliable electrode assembly shaping.

[0030] By limiting the thickness ratio of the shell to the core layer of the core-shell colloid to a range of 0.3:1 to 1:1, sufficient soft shell material is ensured during hot pressing to provide effective initial bonding, while avoiding the problem of diaphragm winding and adhesion caused by excessively thick shells leading to overly soft colloids at room temperature. Simultaneously, the coating surface density of the organic colloid is controlled at 0.3 g / m². 2 ~1.0 g / m 2 This ensures that the adhesive layer has enough bonding points to achieve reliable staged bonding, while avoiding the potential for reduced coating uniformity, obstructed ion conduction, or cost waste caused by excessive stacking of adhesive particles. Thus, while achieving the core invention concept, it also takes into account the processability and storage of the diaphragm.

[0031] A higher shell-to-core thickness ratio (X) results in a greater coating surface density (M) of organic particles, and lower required temperature (T) and pressure (P) for hot-pressing the electrode assembly. This allows for bonding with the electrode sheet at lower temperatures and pressures, meeting the electrode assembly shaping requirements. After high-temperature baking of the cell, the adhesion to the electrode sheet is further improved, enabling the complete transfer of the semi-solid coating to the positive electrode surface and mitigating the negative impact of high hot-pressing parameters on cell performance associated with conventional semi-solid transfer separators. However, excessively high shell-to-core thickness ratios (X) and organic particle coating surface density (M) can cause the separator to self-bond at room temperature, hindering mass production applications.

[0032] By establishing a quantitative relationship between hot-pressing process parameters and key structural parameters of core-shell particles, a clear operational window is provided for manufacturing. This relationship indicates that when the shell layer of the particles is relatively thin (small X value), the hot-pressing temperature and pressure need to be appropriately increased to compensate for insufficient initial bonding ability. Following this relationship in process settings ensures that effective electrode assembly shaping can be achieved with the minimum necessary hot-pressing parameters regardless of the specific core-shell ratio of the particles. This reliably replicates the technical advantage of low-parameter hot-pressing in avoiding electrode damage in large-scale production, while preventing shaping failure due to excessively low parameters.

[0033] According to another aspect of the present invention, a method for preparing the above-mentioned semi-solid separator with low thermal pressure transfer function is provided, comprising the following steps: (1) Preparation of organic colloidal particles: S1 soft monomer is mixed with initiator I to form a soft monomer solution; S2 soft monomer solution is mixed with dispersant; polymerization is carried out at high temperature to obtain core polymer dispersion; S3 hard monomers are emulsified with emulsifiers to form a pre-emulsion; Initiator II was added to the S4 core polymer dispersion and mixed. The pre-emulsion from step S3 was then added, and the reaction was carried out to obtain organic colloidal particles. (2) Mix the components in the semi-solid coating with water to obtain coating slurry I; coat it on one side of the base film to obtain intermediate diaphragm; (3) Mix the components in the adhesive layer with water to obtain coating slurry II; apply it to the surface of the semi-solid coating to obtain a semi-solid diaphragm with low thermal pressure transfer function.

[0034] In some of these embodiments, the initiator I comprises azobisisobutyronitrile (AIBN).

[0035] In some of these embodiments, the dispersant includes a nonionic surfactant.

[0036] In some of these embodiments, the dispersant includes polyvinylpyrrolidone.

[0037] In some embodiments, the emulsifier includes alkyl sulfonates and / or alkylbenzene sulfonates.

[0038] In some embodiments, the initiator II comprises an aqueous initiator.

[0039] In some of these embodiments, the initiator II comprises ammonium persulfate.

[0040] In some embodiments, the conditions for heating polymerization in step S2 include: polymerization at 60℃~80℃, and polymerization time of 6h~10h; In some embodiments, the reaction conditions in step S4 include: a reaction temperature of 60°C to 80°C and a reaction time of 1 hour to 5 hours.

[0041] In some embodiments, the solid content of the coating slurry I is 25% to 40%.

[0042] In some embodiments, the solid content of the coating slurry II is 3% to 10%.

[0043] In some embodiments, an adhesive layer is applied to the uncoated side of the base film of the semi-solid transfer coating diaphragm obtained in step (3) to bond it to the negative electrode.

[0044] According to another aspect of the present invention, an electrode assembly is provided, the electrode assembly comprising a positive electrode, a negative electrode, and a separator; the separator comprising the above-described semi-solid separator with low thermal pressure transfer function or the semi-solid separator with low thermal pressure transfer function prepared by the above-described preparation method.

[0045] In some embodiments, the positive electrode includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, and lithium-rich manganese-based materials.

[0046] In some embodiments, the negative electrode includes at least one of natural graphite, artificial graphite, hard carbon, silicon carbide, and silicon oxide materials.

[0047] In some embodiments, the electrode assembly is prepared by hot pressing, wherein the hot pressing conditions include a hot pressing temperature T of 25°C to 60°C, a hot pressing pressure of 0.3 MPa to 2.1 MPa, and a hot pressing time of 20 s to 300 s.

[0048] According to another aspect of the present invention, a lithium-ion battery is provided, comprising an electrode assembly and an electrolyte; the electrode assembly comprises the aforementioned electrode assembly.

[0049] In some embodiments, the lithium-ion battery preparation process includes: sequentially coating, casing, encapsulating, baking, and injecting electrolyte into the motor assembly, followed by sequential pre-charging, formation, and capacity testing to finally obtain the lithium-ion battery.

[0050] In some of these embodiments, the baking temperature is 90°C to 105°C.

[0051] Implementing the technical solution of the present invention has at least the following beneficial effects: 1. This invention provides a temperature-responsive adhesive layer on the surface of a semi-solid coating. This allows the adhesive layer to provide sufficient initial bonding force to fix the electrode assembly at a lower first temperature (hot-pressing temperature), and a stronger final bonding force to complete the coating transfer at a higher second temperature (baking temperature). This decouples the electrode assembly shaping and complete coating transfer requirements in the process, significantly reducing the temperature and pressure parameters required for the initial hot-pressing step while ensuring the integrity of the final coating transfer. This effectively avoids electrode damage (such as negative electrode shedding) and poor electrolyte wetting caused by excessively high hot-pressing parameters, while ensuring the interface integrity and electrochemical performance of the battery.

[0052] 2. By specifically defining the thermally responsive organic particles as core-shell structured polymers with a particular composition, where the shell layer is a soft monomer with a low glass transition temperature and the core layer is a hard monomer with a high glass transition temperature, the shell layer preferentially softens and becomes viscous in the lower hot-pressing temperature range, providing the initial adhesive force required for electrode assembly shaping; while the core layer remains rigid to prevent excessive adhesion of the particles during storage and winding. In the subsequent higher baking temperature range, the core layer softens and works synergistically with the softened shell layer to provide a significantly enhanced secondary adhesive force, thereby reliably and efficiently achieving the complete transfer of the coating from the diaphragm base film to the electrode. This provides a clear and feasible materials science implementation path for staged bonding functionality.

[0053] 3. This invention provides a semi-solid transfer coating separator that can bond with the electrode at a lower temperature, meeting the electrode assembly shaping requirements. After high-temperature baking of the battery cell, the adhesion to the electrode can be further improved, realizing the complete transfer of the semi-solid coating to the surface of the positive electrode, thus solving the negative impact of the large hot-pressing parameters of conventional semi-solid transfer separators on the battery cell performance.

[0054] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0055] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0056] Figure 1 Photograph of the diaphragm prepared for Comparative Example 6.

[0057] Figure 2 Photograph of the diaphragm prepared in Example 1.

[0058] The accompanying drawings have illustrated specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0059] The present application will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present application.

[0060] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges or individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0061] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0062] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0063] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0064] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0065] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0066] In the field of lithium-ion battery manufacturing, to improve battery safety by completely transferring the functional coating from a semi-solid separator to the surface of the positive electrode, the commonly used technical solution is to coat a polyolefin-based film with a semi-solid coating containing a semi-solid ion-conducting material, and then bond the coating to the positive electrode through a hot-pressing process. Specifically, this method uses heating and pressure to soften and flow the organic binder components in the coating, forming an adhesive interface between the separator and the electrode to achieve coating transfer. The basic working principle is that under the temperature and pressure provided by hot pressing, the polymer binder material in the coating undergoes a glass transition or softens, becoming sticky, thus adhering to the electrode and finally fixing after cooling. Its widespread application is mainly due to its ability to achieve good overall coating transfer and its auxiliary role in thermal stability and ion conduction during subsequent battery operation.

[0067] However, this solution performs poorly when applied to large-scale manufacturing scenarios that prioritize higher production efficiency and lower process damage. A fundamental contradiction lies in the fact that, to optimize the integrity of coating transfer and the initial electrode assembly shaping effect, the inherent design of this solution inevitably requires high hot-pressing temperatures and pressures, which directly damage the mechanical integrity of the electrode sheets and the subsequent wetting effect of the electrolyte. Specifically, in actual cell production, excessively high hot-pressing parameters can easily cause the negative electrode active material to detach from the current collector, i.e., material shedding; at the same time, high pressure excessively compresses the pore structure of the electrode assembly, hindering the penetration and storage of the electrolyte, resulting in poor wetting.

[0068] Through in-depth analysis, the inventors discovered that the root causes of the aforementioned contradictions are multifaceted: From a materials perspective, the adhesive materials used in related technologies typically have a single glass transition temperature, and their softening bonding behavior exhibits a monotonic relationship with temperature, making it difficult to simultaneously meet the phased requirements of effectively "fixing" the electrode assembly at low temperatures and strongly "transferring" the coating at high temperatures. From a process perspective, coupling the two functions of "electrode assembly shaping" and "complete coating transfer," which have different requirements for bonding strength, into a single high-parameter hot-pressing step is the direct cause of the narrow process window and susceptibility to side effects. Furthermore, from an interface physics perspective, once a high-strength bond is formed in one step, any adjustments may damage the already formed interface, resulting in a lack of process controllability. These factors collectively limit the performance ceiling of existing solutions in balancing transfer effectiveness and electrode protection.

[0069] To overcome the aforementioned contradictions, this invention proposes a different technical approach. Its core concept lies in improving the adhesion mechanism during coating transfer by introducing a bonding layer containing thermally responsive organic particles onto the surface of the semi-solid coating. This effectively reduces the temperature and pressure parameters required for the initial hot-pressing process without significantly sacrificing the final integrity of the coating transfer, and avoids electrode damage and wetting degradation caused by these parameters. In other words, it provides a semi-solid coating structure with staged thermally responsive bonding function to solve the compatibility problem caused by high single-stage hot-pressing parameters, achieving the technical effect of completing electrode assembly shaping under low hot-pressing conditions and achieving complete coating transfer during subsequent baking.

[0070] By applying a temperature-responsive adhesive layer to the surface of the composite coating, the adhesive layer provides sufficient initial bonding force to fix the electrode assembly at a lower first temperature (hot-pressing temperature), and provides stronger final bonding force at a higher second temperature (baking temperature) to complete the coating transfer. This synergizes the two functional requirements of electrode assembly shaping and complete coating transfer in the process, significantly reducing the temperature and pressure parameters required for the initial hot-pressing step while ensuring the integrity of the final coating transfer. This effectively avoids electrode damage (such as negative electrode shedding) and poor electrolyte wetting caused by excessively high hot-pressing parameters, while ensuring the interface integrity and electrochemical performance of the battery.

[0071] In this application, "shell" refers to the outer layer of a core-shell structured organic particle configured to soften and provide adhesion in a relatively low first temperature range (such as a hot-pressing temperature range). For example, it may include, but is not limited to, a polymer layer formed by polymerizing a soft monomer component with a low glass transition temperature (Tg), such as at least one of ethyl acrylate, butyl acrylate, and isooctyl acrylate. Specifically, the glass transition temperature of the shell may be -40°C to 25°C, and its thickness ratio to the core layer is 0.3 to 1:1.

[0072] In this application, "core layer" refers to the inner layer portion of a core-shell structured organic particle configured to soften in a relatively high second temperature range (such as a baking temperature range) and provide enhanced adhesion. For example, it may include, but is not limited to, a polymer layer formed by polymerizing a hard monomer component with a high glass transition temperature (Tg), such as at least one of styrene, methyl methacrylate, methyl acrylate, methylstyrene, acrylonitrile, and acrylamide. Specifically, the glass transition temperature of the core layer is 70°C to 105°C.

[0073] In this application, "hot-pressing temperature range" refers to the temperature range used in battery manufacturing processes to initially bond the semi-solid separator and electrode sheets and achieve electrode assembly shaping by applying heat and pressure. For example, it may include, but is not limited to, the temperature range configured to soften and bond the heat-responsive organic adhesive particles in the adhesive layer. Specifically, the hot-pressing temperature range may refer to 25°C to 60°C.

[0074] In this application, "baking temperature range" refers to a higher temperature range used in battery manufacturing processes, following the hot pressing process, to complete the transfer of the coating from the separator to the electrode and / or to achieve other curing and drying purposes. For example, it may include, but is not limited to, temperatures configured to soften and bond the core layer of the heat-responsive organic adhesive particles in the adhesive layer. Specifically, the baking temperature range may refer to 90°C to 105°C, a range typically higher than the hot pressing temperature range.

[0075] In this application, "low-temperature hot-pressure transfer function" refers to the overall characteristic of semi-solid diaphragms and their coating systems to reliably transfer the coating to the electrode under relatively low temperature and pressure process conditions. For example, this may include, but is not limited to, a staged bonding mechanism using an adhesive layer, where only lower parameters (e.g., ≤60℃, ≤2.1MPa) are required to meet the electrode assembly shaping requirements in the initial hot-pressing stage, while the complete transfer of the coating is completed in a subsequent baking stage at a higher temperature, thus avoiding damage to the electrode from a single high-temperature, high-pressure process. Specifically, the process window for achieving this function may refer to a hot-pressing temperature T of 25℃~60℃ and a hot-pressing pressure P of 0.3 MPa~2.1 MPa.

[0076] In this application, "semi-solid coating substrate" refers to a functional coating material layer applied to the separator base membrane to improve battery safety (such as thermal stability and mechanical isolation) and / or ion conductivity. For example, it may include, but is not limited to, a substrate layer containing semi-solid ion-conducting materials such as lithium aluminum titanium phosphate (LATP) and / or lithium lanthanum zirconium oxide (LLZO), which may also contain inorganic ceramic materials such as alumina and boehmite, or reinforcing materials such as rod-shaped organic nanofibers and aramid particles. Specifically, the semi-solid coating substrate can be formed by slurry coating, wherein the solid content of the slurry can be 25% to 40%.

[0077] In this application, "adhesive layer" refers to a functional layer disposed on the surface of the semi-solid coating substrate, designed to achieve adhesion and transfer between the diaphragm coating and the electrode, and comprising thermally responsive organic particles. For example, it may include, but is not limited to, a coating composed of core-shell structured organic particles, a binder, a dispersant, and a wetting agent. Specifically, the coating thickness of the adhesive layer can be 1 μm to 2 μm, the coverage on the semi-solid coating substrate can be 70% to 90%, and it can be formed by coating with a slurry with a solid content of 3% to 10%.

[0078] In this application, the "shell-to-core thickness ratio" and "coating areal density" are key parameters for optimizing the performance of the adhesive layer. The "shell-to-core thickness ratio" generally refers to the relative thickness ratio of the shell to the core in a core-shell structured organic particle, affecting its staged bonding performance and storage processability; the "coating areal density" generally refers to the mass of organic particles coated on a unit area of ​​the diaphragm. For example, this may include, but is not limited to, controlling the shell-to-core thickness ratio within the range of 0.3 to 1:1 and controlling the coating areal density at 0.3 g / m². 2 ~1.0 g / m 2 The range is designed to balance the low-temperature bonding effect, the final transfer effect, and to prevent the diaphragm from self-adheding.

[0079] In this invention, the glass transition temperature can be determined using differential scanning calorimetry (DSC), a conventional method in the art. For example, using a DSC under a nitrogen atmosphere, the temperature is scanned from -80°C to 150°C at a heating rate of 10°C / min, and the inflection point or midpoint of the curve is taken as the glass transition temperature. The particle size of the organic colloidal particles can be obtained by statistical measurement using a laser particle size analyzer or a scanning electron microscope. For example, after appropriately diluting the organic colloidal particle dispersion, its volume average particle size (D50) is measured using a laser particle size analyzer; or, by taking photographs with a scanning electron microscope and using image analysis software, the diameter of at least 100 particles is randomly measured, and the average value is taken.

[0080] The coating thickness can be measured using cross-sectional scanning electron microscopy (SEM). The diaphragm sample is prepared by brittle fracture with liquid nitrogen, and the cross-section is observed using an SEM to measure the thickness of the adhesive layer. Measurements are taken at least 10 times at different locations, and the average value is calculated. Coverage can be evaluated using surface SEM combined with image analysis software. The adhesive layer surface is photographed, and the covered and uncovered (or partially covered) areas are distinguished by contrast. The area percentage of the covered area is calculated.

[0081] The areal density M of the coating can be measured by gravimetric method. Accurately measure the mass of a diaphragm sample with an adhesive layer covering a certain area (e.g., 10 cm × 10 cm), then subtract the mass of a semi-finished diaphragm of the same area without an adhesive layer. The difference is the mass of the adhesive layer on that area, and the areal density M can then be calculated. The following detailed description of this application is provided in conjunction with the accompanying drawings and embodiments. However, the implementation and protection of this invention are not limited thereto. The following embodiments are only some embodiments of this application and are not intended to limit this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0082] Test method: Electrode group hot pressing shaping effect test Test object: An unencapsulated electrode assembly assembled with the diaphragm under test and positive and negative electrode sheets after being stacked or wound.

[0083] Testing equipment: Flat plate hot press, equipped with a precise temperature and pressure control system.

[0084] Test procedure: Place the electrode assembly between the plates of the hot press and perform hot pressing according to the set temperature (T), pressure (P), and time. After hot pressing, remove the electrode assembly and visually and manually inspect the edges of the electrode assembly for delamination, cracking, or misalignment of the electrode sheets.

[0085] Judgment criteria: If the electrode assembly edges are intact, with no visible delamination or cracking, and each layer of electrode sheets is well aligned, and there is no looseness when slight manual pressure is applied, it is judged as "OK" (effective shaping); otherwise, if any of the above defects occur, it is judged as "NG" (shaping failure).

[0086] Negative electrode material loss assessment Test subject: Lithium-ion batteries that have completed formation, capacity testing, and full charging.

[0087] Test procedure: Disassemble the fully charged battery in a dry chamber, carefully separate the electrode assembly, and remove the negative electrode. Under sufficient light, visually inspect the surface of the negative electrode, especially the edges and the area corresponding to the folding of the separator.

[0088] Judgment criteria: If the surface of the negative electrode is smooth, the active material coating is intact, and there are no visible particulate materials falling off or coating defects, it is recorded as "No"; if active material particles are observed falling off or exposed spots are left on the current collector, it is recorded as "Yes", and the location and approximate extent of the material falling off are noted.

[0089] Battery cycle performance test Test equipment: LAND CT2001A battery test system, constant temperature chamber.

[0090] Test conditions: Ambient temperature 25±2℃.

[0091] Test program: a. Charge the battery at a constant current of 0.5C to the upper limit voltage (e.g., 4.2V), then switch to constant voltage charging until the current drops to 0.05C, and let it stand for 5 minutes.

[0092] b. Discharge at a constant current of 1C to the cutoff voltage (e.g., 3.0V), and record the initial discharge capacity C0.

[0093] c. Repeat steps a and b to perform continuous charge-discharge cycles. d. Record the discharge capacity C500 of the 500th cycle.

[0094] Data processing: Capacity retention rate (%) = (C500 / C0) × 100%. At least three batteries should be tested, and the average value should be taken.

[0095] Diaphragm self-adhesion assessment Test object: The diaphragm to be tested after being wound up.

[0096] Test procedure: Store the diaphragm roll vertically at room temperature (25°C) for 7 days. Then, rewind it in a drying room at a low speed (e.g., 5 m / min).

[0097] Judgment criteria: If the unwinding process is smooth, the membrane layers are easy to separate, and there is no damage to the membrane surface, stretching deformation, or inability to unwind normally due to adhesion, it is judged as "non-self-adhesive"; if there is obvious resistance during unwinding, the membrane layers are not easy to separate, or even cause the membrane surface to tear or be permanently deformed, it is judged as "self-adhesive".

[0098] Coating transfer rate Test subject: The electrode plates of a disassembled battery cell; Test procedure: The coating is white and the positive electrode is black. The coating transfer rate is calculated by the proportion of the white area on the positive electrode surface after transfer. The actual transfer rate is >98%.

[0099] Example 1 A method for preparing a semi-solid membrane with low thermal pressure transfer function includes the following steps: (1) Preparation of organic colloidal particles: S1. Mix 100 g of hard monomer (isocyanate acrylate: ethyl acrylate = 2:8) with 1 g of initiator azobisisobutyronitrile (monomer mass 1%) to form a hard monomer solution. S2. Dissolve the dispersant polyvinylpyrrolidone in deionized water to prepare an aqueous dispersant solution with a concentration of 1.5 wt%. S3, 100g of hard monomer solution and 1000g of dispersant aqueous solution of S2 are stirred and mixed; S4. The temperature is raised to 70℃ for polymerization. After 8 hours, the polymerization is completed, and an aqueous dispersion of the core polymer is obtained. S5. Mix 50 g of soft monomer (styrene: methyl acrylate = 9:1) with 500 g of aqueous solution containing 2 wt% emulsifier (sodium dodecyl sulfonate) and emulsify to form a pre-emulsion; S6. Add 0.4 g of water-soluble ammonium persulfate to the reaction product of step S4, and simultaneously start adding the pre-emulsion obtained in step S5. The addition is completed in 2 hours. Raise the temperature to 70°C and keep the reaction at that temperature for 3 hours. After cooling, organic colloid particles are obtained.

[0100] The prepared organic colloidal particles had a core layer Tg of 80℃ and a shell layer Tg of -30℃; the thickness ratio X of the shell layer to the core layer was 0.5:1, and the particle size was 0.8μm.

[0101] (2) Preparation of semi-solid coating slurry: 40 parts of lithium aluminum titanium phosphate (LATP), 50 parts of alumina, 10 parts of rod-shaped organic nanofibers (rod-shaped organic nanofibers formed by carboxylation and grafting of natural cellulose, purchased from Guilin Qihong Technology Co., Ltd.), 4 parts of polymethyl acrylate binder, 0.5 parts of sodium carboxylate dispersant and water are thoroughly mixed to obtain a coating slurry with a solid content of 30%; the slurry is coated on one side of a 7μm polyethylene film using a micro-gravure roller to obtain an intermediate semi-solid coated diaphragm; (3) Preparation of adhesive layer: 100 parts of organic adhesive particles, 4.5 parts of polymethyl methacrylate adhesive, 0.3 parts of carboxylic acid amine dispersant, 0.2 parts of polydimethylsiloxane wetting agent and deionized water were thoroughly mixed to obtain a coating slurry with a solid content of 7%; the slurry was coated on the surface of the semi-solid coating using a micro-gravure roller with an area density of 0.6 g / m². 2 A semi-solid transfer coating membrane was obtained by coating a thickness of 1.5 μm and a coverage of 82%.

[0102] (4) On the other side of the obtained semi-solid transfer-coated membrane base film (the side without the semi-solid transfer coating), a conventional PVDF spray coating is applied. The PVDF used is Dongyangguang 2602 grade PVDF with a coating surface density of 0.5 g / m³. 2 .

[0103] Preparation of lithium-ion batteries: Preparation of positive electrode sheet: The medium-nickel ternary positive electrode active material, binder PVDF, conductive agent carbon black, and conductive agent carbon nanotube are mixed at a mass ratio of 97.1:1.0:1.5:0.4 and added to the solvent NMP. The mixture is stirred thoroughly to obtain a positive electrode slurry. The positive electrode slurry is then coated on both sides of carbon-coated aluminum foil, dried, compacted, and cut into sheets to obtain the positive electrode sheet. Preparation of negative electrode sheet: Artificial graphite, binder PAA, binder SBR, CMC thickener, and conductive agent carbon black are mixed in a mass ratio of 96.3:2.3:0.5:0.4:0.5 and added to solvent water. The mixture is stirred thoroughly to obtain a negative electrode slurry. The negative electrode slurry is then coated on both sides of a copper foil, dried, compacted, and cut into sheets to obtain the negative electrode sheet. The prepared electrodes and separators were subjected to stacking and hot pressing experiments. The battery was of VDA size, and the hot pressing time was uniformly 120 seconds. The hot pressing process parameters were determined according to Equation 1 and Equation 2.

[0104] X is the ratio of the shell to the core thickness of the organic colloidal particle; mg / m 2The coating density of the adhesive layer on the base film; T℃ is the hot-pressing temperature; P MPa is the hot-pressing pressure; The hot pressing process satisfies the following relationships: Relationship 1 and Relationship 2: Relationship 1: T≥25+35(1- ); Relationship 2: P≥0.3+1.8(1- ); Where 0.3≤X≤1.0; 0.3≤M≤1.0.

[0105] In Example 1, X=0.5 and M=0.6. Substituting these values ​​into Equation 1, we obtain T≥46.88℃; substituting them into Equation 2, we obtain P≥1.42 MPa. The specific hot-pressing conditions are shown in Table 1.

[0106] After hot pressing, the battery cells that meet the electrode hardness requirements are inserted into the casing, followed by a cell baking process at 100℃ for 8 hours. After electrolyte injection into the electrode assembly, the cells are pre-charged and formed to obtain a lithium battery.

[0107] Example 2 The difference between Example 2 and Example 1 is as follows: (1) Preparation of organic colloidal particles: S1. Mix 100 g of hard monomer (isocyanate acrylate: ethyl acrylate = 2:8) with 1 g of initiator azobisisobutyronitrile (monomer mass 1%) to form a hard monomer solution. S2. Dissolve the dispersant polyvinylpyrrolidone in deionized water to prepare an aqueous dispersant solution with a concentration of 1.5 wt%. S3, 100g of hard monomer solution and 1000g of dispersant aqueous solution of S2 are stirred and mixed; S4. The temperature is raised to 70℃ for polymerization. After 8 hours, the polymerization is completed, and an aqueous dispersion of the core polymer is obtained. S5. Mix 30 g of soft monomer (styrene: methyl acrylate = 9:1) with 500 g of aqueous solution containing 2 wt% emulsifier (sodium dodecyl sulfonate) to form a pre-emulsion; S6. Add 0.4 g of water-soluble ammonium persulfate to the reaction product of step S4, and simultaneously start adding the pre-emulsion obtained in step S5. The addition is completed in 2 hours. Raise the temperature to 70°C and keep the reaction at that temperature for 3 hours. After cooling, organic colloid particles are obtained.

[0108] The organic colloidal particles prepared had a core layer Tg of 80℃ and a shell layer Tg of -30℃; the thickness ratio X of the shell layer to the core layer was 0.3:1, and the particle size was 0.8μm.

[0109] The rest is the same as in Example 1.

[0110] Example 3 The difference between Example 3 and Example 1 is that: (1) Preparation of organic colloidal particles: S1. Mix 100 g of hard monomer (isocyanate acrylate: ethyl acrylate = 2:8) with 1 g of initiator azobisisobutyronitrile (monomer mass 1%) to form a hard monomer solution. S2. Dissolve the dispersant polyvinylpyrrolidone in deionized water to prepare an aqueous dispersant solution with a concentration of 1.5 wt%. S3, 100g of hard monomer solution and 1000g of dispersant aqueous solution of S2 are stirred and mixed; S4. The temperature is raised to 70℃ for polymerization. After 8 hours, the polymerization is completed, and an aqueous dispersion of the core polymer is obtained. S5. Mix 100 g of soft monomer (styrene: methyl acrylate = 9:1) with 500 g of aqueous solution containing 2 wt% emulsifier (sodium dodecyl sulfonate) to form a pre-emulsion; S6. Add 0.4 g of water-soluble ammonium persulfate to the reaction product of step S4, and simultaneously start adding the pre-emulsion obtained in step S5. The addition is completed in 2 hours. Raise the temperature to 70°C and keep the reaction at that temperature for 3 hours. After cooling, organic colloid particles are obtained.

[0111] The prepared organic colloidal particles had a core layer Tg of 80℃ and a shell layer Tg of -30℃; the shell-to-core layer thickness ratio X was 1:1, and the particle size was 0.8μm.

[0112] The rest is the same as in Example 1.

[0113] Example 4 The difference between Example 4 and Example 1 is as follows: The surface density M of the adhesive layer is 0.3 g / m². 2 .

[0114] The rest is the same as in Example 1.

[0115] Example 5 The difference between Example 5 and Example 1 is that: The surface density M of the organic colloid particles coating is 1.0 g / m². 2 .

[0116] The rest is the same as in Example 1.

[0117] Example 6 The difference between Example 6 and Example 1 is that: Preparation of organic colloidal particles: S1. Mix 100 g of hard monomer (methyl acrylate: ethyl acrylate = 8:2) with 1 g of initiator azobisisobutyronitrile (1 g of monomer mass) to form a hard monomer solution. S2. Dissolve the dispersant polyvinylpyrrolidone in deionized water to prepare an aqueous dispersant solution with a concentration of 1.5 wt%. S3, 100 mL of hard monomer solution and 1000 mL of dispersant aqueous solution are stirred and mixed; S4. The temperature is raised to 70℃ for polymerization. After 8 hours, the polymerization is completed, and an aqueous dispersion of the core polymer is obtained. S5. Mix 50 g of the soft monomer (methylstyrene:acrylonitrile = 6:4) with 500 g of an aqueous solution containing 2 wt% emulsifier (sodium dodecyl sulfonate) to form a pre-emulsion; S6. Add 0.4 g of water-soluble ammonium persulfate to the reaction product of step S4, and simultaneously start adding the pre-emulsion obtained in step S5. The addition is completed in 2 hours. Heat to 70°C and keep the temperature for 3 hours. After cooling, organic colloids are obtained.

[0118] By selecting and combining the monomers and their proportions used in the synthesis, the organic colloidal particles prepared had a core layer Tg of 105℃ and a shell layer Tg of 25℃; the thickness ratio X of the shell layer to the core layer was 0.5:1, and the particle size was 0.8μm.

[0119] The rest is the same as in Example 1.

[0120] Example 7 The difference between Example 7 and Example 1 is that: Preparation of organic colloidal particles: S1. Mix 100 g of hard monomer (isocyanate acrylate: ethyl acrylate = 4:6) with 1 g of initiator azobisisobutyronitrile (1% of monomer mass) to form a hard monomer solution. S2. Dissolve the dispersant polyvinylpyrrolidone in deionized water to prepare an aqueous dispersant solution with a concentration of 1.5 wt%. S3, 100 mL of hard monomer solution and 1000 mL of dispersant aqueous solution are stirred and mixed; S4. The temperature is raised to 70℃ for polymerization. After 8 hours, the polymerization is completed, and an aqueous dispersion of the core polymer is obtained. S5. Mix 50 g of the soft monomer (styrene:acrylonitrile = 2:8) with 500 g of an aqueous solution containing 2 wt% emulsifier (sodium dodecyl sulfonate) and emulsify to form a pre-emulsion; S6. Add 0.4 g of water-soluble ammonium persulfate to the reaction product of step S4, and simultaneously start adding the pre-emulsion obtained in step S5. The addition is completed in 2 hours. Heat to 70°C and keep the temperature for 3 hours. After cooling, organic colloids are obtained.

[0121] By selecting and combining the monomers and their proportions used in the synthesis, the organic colloidal particles prepared had a core layer Tg of 70℃ and a shell layer Tg of -40℃; the thickness ratio X of the shell layer to the core layer was 0.5:1, and the particle size was 0.8μm.

[0122] The rest is the same as in Example 1.

[0123] Example 8 The difference between Example 8 and Example 1 is that: (3) Preparation of adhesive layer: 100 parts organic adhesive particles, 2 parts polyethyl acrylate adhesive, 0.1 parts sodium carboxylate dispersant, 0.5 parts polyethylene glycol wetting agent and deionized water are thoroughly mixed to obtain a coating slurry with a solid content of 7%; the slurry is coated on the surface of the semi-solid coating using a micro-gravure roller with an area density of 0.6 g / m². 2 A semi-solid transfer coating membrane with a coating thickness of 1.5 μm was obtained.

[0124] The rest is the same as in Example 1.

[0125] Example 9 The difference between Example 9 and Example 1 is that: (3) Preparation of adhesive layer: 100 parts organic adhesive particles, 7 parts polymethyl acrylate adhesive, 0.5 parts carboxylic acid amine dispersant, 0.1 parts polyoxyethylene ether wetting agent and deionized water are thoroughly mixed to obtain a coating slurry with a solid content of 7%; the slurry is coated on the surface of the semi-solid coating using a micro-gravure roller with an area density of 0.6 g / m 2 A semi-solid transfer coating membrane with a coating thickness of 1.5 μm was obtained.

[0126] The rest is the same as in Example 1.

[0127] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the thickness ratio of the shell to the core is different. In Comparative Example 1, the thickness ratio X of the shell to the core is 0.2:1.

[0128] The rest is the same as in Example 1.

[0129] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the thickness ratio of the shell to the core is different. In Comparative Example 2, the thickness ratio X of the shell to the core is 1.1:1.

[0130] The rest is the same as in Example 1.

[0131] Comparative Example 3 The difference between Comparative Example 3 and Example 1 lies in the areal density M of the organic particles. The areal density M of Comparative Example 3 is 0.2 g / m². 2 .

[0132] Comparative Example 4 The difference between Comparative Example 4 and Example 1 lies in the areal density M of the organic particles. The areal density M of Comparative Example 4 is 1.1 g / m². 2 .

[0133] The rest is the same as in Example 1.

[0134] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that no organic adhesive particles are added to the adhesive layer.

[0135] The rest is the same as in Example 1.

[0136] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that a commercially available conventional diaphragm was used.

[0137] The rest is the same as in Example 1.

[0138] Comparative Examples 2 and 4 cannot be practically applied due to the self-adhesion problem of the diaphragm after winding.

[0139] Table 1. Hot-press analysis of battery electrode packs prepared using the separators of Examples 1-9 and Comparative Examples 1-6 The separators prepared in Examples 1-7 and Comparative Examples 1-6 were used to insert cells with sufficient electrode hardness into the casing according to the data in Table 1, and lithium batteries were obtained according to the method in Example 1. After a full charge, the cell interface was disassembled, and the amount of material falling off the negative electrode was collected. The cycle capacity of the batteries was then tested.

[0140] Table 2 Performance analysis of batteries prepared using the separators of Examples 1-9 and Comparative Examples 1-6 As shown in Comparative Examples 1-5 of Table 2, when the thickness ratio of the shell to the core layer needs to be maintained at (0.3~1.0):1, the coating surface density on the semi-solid coating substrate is 0.3~1.0 g / m³. 2 At this time, it can achieve bonding with the electrode sheet at lower temperatures and pressures, meeting the electrode assembly shaping requirements. Comparing groups 91 / 10 / 15, it can be seen that if the thickness ratio X of the shell layer to the core layer and the coating surface density M of the organic adhesive particles are too high, the diaphragm will self-bond at room temperature, making it unsuitable for mass production and application.

[0141] As shown in Table 2, using the semi-solid separator with low-temperature hot-pressing transfer function of the present invention, under low-temperature and low-pressure hot-pressing parameters, can minimize the damage to the electrode sheet caused by the hot-pressing process, avoid the negative electrode sheet from falling off, and achieve good electrolyte wetting effect and better cycle capacity retention.

[0142] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0143] The basic principles of the present invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in the present invention are merely examples and not limitations, and should not be considered as essential features of each embodiment of the present invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the present invention to the necessity of employing the aforementioned specific details.

[0144] In the foregoing description of this specification, references to terms such as "one embodiment," "another embodiment," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment is included in at least one embodiment of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples, without contradiction. Additionally, it should be noted that in this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0145] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention 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; and these 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 the present invention.

Claims

1. A semi-solid membrane with low thermal pressure transfer function, characterized in that, The semi-solid membrane includes a base membrane and a semi-solid coating disposed on the surface of the base membrane; The semi-solid coating includes a semi-solid coating body and an adhesive layer disposed on the surface of the semi-solid coating body; The adhesive layer includes organic adhesive particles; The organic colloidal particles include a core-shell polymer, and the organic colloidal particles include a shell layer and a core layer; The shell is composed of a soft monomer component with a low glass transition temperature and is configured to soften and provide adhesion in the hot-pressing temperature range. The core layer is composed of a hard monomer component with a high glass transition temperature and is configured to soften within the baking temperature range and provide transfer functionality.

2. The semi-solid separator with low thermal pressure transfer function according to claim 1, characterized in that, The hard monomer includes at least one of styrene, methyl methacrylate, methyl methacrylate, methyl styrene, acrylonitrile, and acrylamide; And / or, the soft monomer includes at least one of ethyl acrylate, butyl acrylate, and isooctyl acrylate; And / or, the glass transition temperature of the shell is -40℃ to 25℃; And / or, the glass transition temperature of the core layer is 70°C to 105°C; And / or, the particle size of the organic colloidal particles is 0.3 μm to 1.0 μm; And / or, the thickness of the adhesive layer coated on the base film is 1μm~2μm; And / or, the adhesive layer has a coverage of 70% to 90% on the base film.

3. The semi-solid separator with low thermal pressure transfer function according to claim 1 or 2, characterized in that, Based on a total mass of 100 parts of organic colloid particles, the adhesive layer further comprises 2 to 7 parts of binder, 0.1 to 0.5 parts of dispersant, and 0.1 to 0.6 parts of wetting agent; Preferably, the adhesive comprises at least one of polyacrylic acid compounds and polyacrylate compounds; more preferably, the adhesive comprises at least one of polymethyl methacrylate, polymethyl methacrylate, polyethyl methacrylate, or polyethyl methacrylate. Preferably, the dispersant comprises a carboxylate compound; more preferably, the dispersant comprises at least one of sodium carboxylate and carboxylic amine. Preferably, the wetting agent includes at least one of polyethylene glycol, polydimethylsiloxane, and polyoxyethylene ether; And / or, the semi-solid coating substrate comprises a semi-solid ion-conducting material; preferably, the semi-solid coating substrate comprises lithium titanium aluminum phosphate and / or lithium lanthanum zirconium oxide; Preferably, the semi-solid coating body further includes at least one of inorganic ceramic material, rod-shaped organic nanofiber material, rod-shaped PI fiber material, and aqueous aramid particles; More preferably, the inorganic ceramic material includes at least one of alumina, boehmite, magnesium hydroxide, barium sulfate, and silicon dioxide; More preferably, the rod-shaped organic nanofiber material includes rod-shaped organic nanofiber material formed by carboxylation and grafting of natural cellulose; And / or, the base film comprises at least one of polyethylene, polypropylene, polyimide, and aramid; And / or, the thickness of the base film is 3μm~25μm.

4. The semi-solid separator with low thermal pressure transfer function according to claim 1 or 2, characterized in that, X is the ratio of the shell to the core thickness of the organic colloidal particle; mg / m 2 The adhesive layer is the surface density of the coating on the base film; T℃ is the hot-pressing temperature; PMPa is the hot-pressing pressure. The hot pressing process satisfies the following relationships: Relationship 1 and Relationship 2: Relationship 1: T≥25+35(1- ); Relationship 2: P≥0.3+1.8(1- ); Where 0.3≤X≤1.0; 0.3≤M≤1.

0.

5. A method for preparing a semi-solid membrane with low thermal pressure transfer function as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Preparation of organic colloidal particles: S1 soft monomer is mixed with initiator I to form a soft monomer solution; S2 soft monomer solution is mixed with dispersant; polymerization is carried out at high temperature to obtain core polymer dispersion; S3 hard monomers are emulsified with emulsifiers to form a pre-emulsion; Initiator II was added to the S4 core polymer dispersion and mixed. The pre-emulsion from step S3 was then added, and the reaction was carried out to obtain organic colloidal particles. (2) Mix the components in the semi-solid coating with water to obtain coating slurry I; coat it on one side of the base film to obtain intermediate diaphragm; (3) Mix the components in the adhesive layer with water to obtain coating slurry II; apply it to the surface of the semi-solid coating to obtain a semi-solid diaphragm with low thermal pressure transfer function.

6. The preparation method according to claim 5, characterized in that, The initiator I includes azobisisobutyronitrile; And / or, the dispersant comprises a nonionic surfactant, preferably, the dispersant comprises polyvinylpyrrolidone; And / or, the emulsifier includes alkyl sulfonates and / or alkylbenzene sulfonates; And / or, the initiator II comprises an aqueous initiator, preferably, the initiator II comprises ammonium persulfate; And / or, the conditions for heating polymerization in step S2 include: polymerization at 60℃~80℃, polymerization time of 6h~10h; And / or, the reaction conditions in step S4 include: reaction temperature 60℃~80℃, reaction time 1h~5h; And / or, the solid content of the coating slurry I is 25%~40%; And / or, the solid content of the coating slurry II is 3%~10%; And / or, it also includes applying an adhesive layer to the side of the base film of the semi-solid separator with low thermal pressure transfer function obtained in step (2) that is not coated with a semi-solid coating, so as to bond it to the negative electrode.

7. An electrode assembly, characterized in that, The electrode assembly includes a positive electrode, a negative electrode, and a separator; the separator includes a semi-solid separator with low thermal pressure transfer function as described in any one of claims 1-4 or a semi-solid separator with low thermal pressure transfer function prepared by the preparation method described in claims 5 or 6.

8. The electrode assembly according to claim 7, characterized in that, The positive electrode includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, and lithium-rich manganese-based materials. And / or, the negative electrode includes at least one of natural graphite, artificial graphite, hard carbon, silicon carbide, and silicon oxide materials; And / or, the semi-solid transfer coating on the semi-solid separator with low thermal pressure transfer function faces and contacts the positive electrode.

9. The electrode assembly according to claim 7 or 8, characterized in that, The electrode assembly is prepared by hot pressing. The hot pressing conditions include a hot pressing temperature T of 25℃~60℃, a hot pressing pressure of 0.3 MPa~2.1 MPa, and a time of 20 s~300 s.

10. A lithium-ion battery, characterized in that, It includes an electrode assembly and an electrolyte; the electrode assembly includes the electrode assembly according to claim 8 or 9.

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