Phenolic resin organic particle and preparation method therefor, separator, secondary battery cell, battery device, and electric device

Abstract

Provided in the present disclosure are a phenolic resin organic particle and a preparation method therefor, a separator, a secondary battery cell, a battery device, and an electric device. The separator comprises a porous base membrane and a coating located on at least one side of the porous base membrane, wherein the coating comprises phenolic resin organic particles, the volume median diameter Dv50 of the phenolic resin organic particles is 100-800 nm, and the particle size distribution (Dv90-Dv10) / Dv50 of the phenolic resin organic particles is 1.4-3. The secondary battery cell has a high mass energy density, high reliability and good cycle performance.

Description

Phenolic resin organic particles and their preparation methods, separators, secondary battery cells, battery devices and electrical devices

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202410946540.2, filed on July 15, 2024, entitled “Phenolic Resin Organic Particles and Preparation Method Thereof, Separator Membrane, Battery Cell, and Electrical Device Thereof,” and Chinese Patent Application No. 202411384303.8, filed on September 30, 2024, entitled “Phenolic Resin Organic Particles and Preparation Method Thereof, Separator Membrane, Secondary Battery Cell, Battery Device, and Electrical Device Thereof,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a phenolic resin organic particle and its preparation method, a separator, a secondary battery cell, a battery device, and an electrical device. Background Technology

[0004] As the application range of rechargeable battery cells becomes increasingly widespread, the demands on them are also growing, with higher requirements for energy density, lifespan, and reliability. Therefore, how to achieve higher energy density and better cycle stability in rechargeable battery cells while maintaining high reliability is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] This disclosure provides a phenolic resin organic particle and its preparation method, a separator, a secondary battery cell, a battery device, and an electrical device. The secondary battery cell has high energy density, high reliability, and good cycle performance.

[0006] In a first aspect, this disclosure provides a separating membrane, comprising a porous base membrane and a coating located on at least one side of the porous base membrane, the coating comprising phenolic resin organic particles, wherein the volume distribution particle size Dv50 of the phenolic resin organic particles is 100nm-800nm, and the particle size distribution (Dv90-Dv10) / Dv50 of the phenolic resin organic particles is 1.4-3.

[0007] Phenolic resin organic particles have low density, allowing secondary battery cells to achieve higher gravimetric energy density. The volumetric particle size distribution (Dv50) of these phenolic resin organic particles ranges from 100 nm to 800 nm, and the particle size distribution (Dv90-Dv10) / Dv50 is 1.4-3, enabling close packing of these particles. By using phenolic resin organic particles meeting these parameters in a separator, they generate forces that resist separator shrinkage, thereby improving the overall thermal shrinkage of the separator, enhancing its heat resistance, and increasing the reliability of the secondary battery cell. Furthermore, the use of phenolic resin organic particles meeting these parameters in the separator also improves its air permeability, which in turn enhances the cycle performance of the secondary battery cell. Therefore, the separator disclosed in this invention enables secondary battery cells to possess high gravimetric energy density, high reliability, and excellent cycle performance.

[0008] In some embodiments, the volume distribution particle size Dv50 of the phenolic resin organic particles is 200 nm-600 nm. When the volume distribution particle size Dv50 of the phenolic resin organic particles is within this range, its use in a separator membrane can improve the separator membrane's heat resistance and air permeability, thereby improving the cycle performance of the secondary battery cells.

[0009] In some embodiments, the particle size distribution (Dv90-Dv10) / Dv50 of the phenolic resin organic particles is 1.6-2.7. When the particle size distribution (Dv90-Dv10) / Dv50 of the phenolic resin organic particles is within the above range, its use in a separator membrane can improve the separator membrane's heat resistance and air permeability, thereby improving the cycle performance of the secondary battery cells.

[0010] In some embodiments, the volume distribution particle size Dv90 of the phenolic resin organic particles is 800nm-1800nm, optionally 820nm-1250nm. When the volume distribution particle size Dv90 of the phenolic resin organic particles is within the above range, its use in a separator membrane is beneficial for improving the coating consistency of the separator membrane.

[0011] In some embodiments, the volume distribution particle size Dv10 of the phenolic resin organic particles is 50nm-200nm, optionally 90nm-185nm. When the volume distribution particle size Dv10 of the phenolic resin organic particles is within the above range, its use in a separator membrane can reduce the risk of pore blockage.

[0012] In some embodiments, the phenolic resin organic particles have no melting point. The fact that the phenolic resin organic particles of this disclosure have no melting point indicates that they possess good heat resistance and thermal stability, thereby better resisting the thermal shrinkage of the separator, improving the heat resistance of the separator, and enhancing the reliability of the secondary battery cells.

[0013] In some embodiments, the phenolic resin organic particles have no glass transition temperature below 300°C.

[0014] Phenolic resin organic particles have no glass transition temperature below 300℃, indicating that they have good heat resistance and thermal stability. This allows them to better resist the thermal shrinkage of porous base films, improve the heat resistance of separators, and enhance the reliability of secondary battery cells.

[0015] In some embodiments, the phenolic resin organic particles are thermosetting propylene resins.

[0016] In some embodiments, the true density of the phenolic resin organic particles is 1.0 g / cm³. 3 -1.4g / cm 3 This allows secondary battery cells using the separator membrane disclosed herein to have a higher mass energy density.

[0017] In some embodiments, the phenolic resin organic particles in the coating contain 50%-99% by mass, based on the total mass of the coating.

[0018] In some embodiments, the thickness of the coating is 0.5 μm-5 μm.

[0019] In some embodiments, the areal density of the coating is 0.45 g / m³. 2 -4.5g / m 2 .

[0020] In some embodiments, the ratio of the volume distribution particle size Dv50 of the phenolic resin organic particles to the average pore size of the porous base membrane is greater than or equal to 1.5.

[0021] In some embodiments, the separation film is heated at a constant temperature of 130°C for 1 hour, and the longitudinal thermal shrinkage rate is less than or equal to 2%.

[0022] In some embodiments, the separator is heated at a constant temperature of 130°C for 1 hour, and the transverse thermal shrinkage rate is less than or equal to 2%.

[0023] In some embodiments, the air permeability of the isolation membrane is 160s / 100mL-230s / 100mL.

[0024] Secondly, this disclosure provides a phenolic resin organic particle, wherein the volume distribution particle size Dv50 of the phenolic resin organic particle is 100nm-800nm, and the particle size distribution (Dv90-Dv10) / Dv50 of the phenolic resin organic particle is 1.4-3.

[0025] In some embodiments, the volume distribution particle size Dv50 of the phenolic resin organic particles is 200nm-600nm.

[0026] In some embodiments, the particle size distribution (Dv90-Dv10) / Dv50 of the phenolic resin organic particles is 1.6-2.7.

[0027] In some embodiments, the volume distribution particle size Dv90 of the phenolic resin organic particles is 800nm-1800nm, and can be selected as 820nm-1250nm.

[0028] In some embodiments, the volume distribution particle size Dv10 of the phenolic resin organic particles is 50nm-200nm, and can be selected as 90nm-185nm.

[0029] In some embodiments, the phenolic resin organic particles have no melting point.

[0030] In some embodiments, the phenolic resin organic particles have no glass transition temperature below 300°C.

[0031] In some embodiments, the phenolic resin organic particles are thermosetting propylene resins.

[0032] In some embodiments, the true density of the phenolic resin organic particles is 1.0 g / cm³. 3 -1.4g / cm 3 .

[0033] Thirdly, this disclosure provides a method for preparing phenolic resin organic particles, comprising the following steps: providing a first-order phenolic resin material; heating and curing the first-order phenolic resin material to obtain a phenolic resin material to be crushed; crushing the phenolic resin material to be crushed to obtain crushed phenolic resin organic particles; mixing the crushed phenolic resin organic particles with a first dispersant and water to obtain a sand milling slurry, followed by sand milling and filtration to obtain phenolic resin organic particles, wherein the first dispersant is a polymeric dispersant, the volume distribution particle size Dv50 of the phenolic resin organic particles is 100nm-800nm, and the particle size distribution (Dv90-Dv10) / Dv50 of the phenolic resin organic particles is 1.4-3.

[0034] The preparation method provided in this disclosure incorporates a polymeric dispersant during the sand milling process. This polymeric dispersant reduces inter-particle interactions, helping to decrease particle agglomeration and maintain a uniform particle distribution, thereby producing phenolic resin organic particles with small particle size and narrow particle size distribution. Furthermore, the introduction of the polymeric dispersant can increase the solids content of the sand milling slurry while reducing its viscosity, thus improving milling efficiency. It also allows for closer packing of the phenolic resin organic particles, further enhancing the heat resistance of the separating membrane.

[0035] In some embodiments, the first dispersant includes one or more of polyether dispersants, polyacrylic acid dispersants, polycarboxylate dispersants, polyvinylpyrrolidone, and polyethylene glycol. The type of the first dispersant being within the above-mentioned range can further optimize the solid content and viscosity of the milling slurry, which is beneficial for preparing phenolic resin organic particles with small particle size and narrow particle size distribution. It also facilitates the close packing of phenolic resin organic particles, thereby enabling the separator to have better heat resistance and air permeability, and giving the secondary battery cell better cycle performance.

[0036] In some embodiments, the mass of the first dispersant is 0.01%-2% of the mass of the crushed phenolic resin organic particles. The content of the first dispersant within the above range can further optimize the solid content and viscosity of the milling slurry, which is beneficial for preparing phenolic resin organic particles with small particle size and narrow particle size distribution. It also promotes the close packing of the phenolic resin organic particles, thereby enabling the separator to have better heat resistance and air permeability, and giving the secondary battery cells better cycle performance.

[0037] Fourthly, this disclosure provides another method for preparing phenolic resin organic particles, comprising the following steps: providing a foaming agent and a first-order phenolic resin material; mixing the foaming agent and the first-order phenolic resin material uniformly, and then heating and curing to obtain a phenolic resin material to be crushed; crushing the phenolic resin material to be crushed to obtain crushed phenolic resin organic particles; and milling the crushed phenolic resin organic particles to obtain phenolic resin organic particles, wherein the volume distribution particle size Dv50 of the phenolic resin organic particles is 100nm-800nm, and the particle size distribution (Dv90-Dv10) / Dv50 of the phenolic resin organic particles is 1.4-3.

[0038] In the process of heating and curing phenolic resin materials, a foaming agent is added. During the curing process, the foaming agent can generate gas through decomposition or volatilization, causing the phenolic resin material to expand and form foam. This alters the structure and properties of the phenolic resin material. The gas can diffuse through the membrane wall of the phenolic resin material, inhibiting the expansion of the cured cross-linked network. This allows the phenolic resin material to be easily processed through crushing and milling to obtain phenolic resin organic particles with small particle size and narrow particle size distribution. Therefore, the preparation method provided in this disclosure can efficiently obtain phenolic resin organic particles with small particle size and narrow particle size distribution.

[0039] In some embodiments, the mass of the foaming agent is 1%-20% of the mass of the methyl phenolic resin material. An appropriate amount of foaming agent is beneficial for obtaining phenolic resin organic particles with small particle size and narrow particle size distribution.

[0040] In some embodiments, the foaming agent includes organic foaming agents and / or inorganic foaming agents.

[0041] In some embodiments, a second dispersant is added when the crushed phenolic resin organic particles are sand-milled.

[0042] In some embodiments, the second dispersant includes one or more of polyether dispersants, polyacrylic acid dispersants, polycarboxylate dispersants, polyvinylpyrrolidone, and polyethylene glycol. The type of the second dispersant within the above-mentioned range can optimize the solid content and viscosity of the milling slurry, thereby facilitating the preparation of phenolic resin organic particles with small particle size and narrow particle size distribution. It also promotes the close packing of phenolic resin organic particles, which in turn gives the separator better heat resistance and air permeability, resulting in better cycle performance of the secondary battery cells.

[0043] In some embodiments, the mass of the second dispersant is 0.01%-2% of the mass of the crushed phenolic resin organic particles. The content of the second dispersant within the above range can optimize the solid content and viscosity of the milling slurry, thereby facilitating the preparation of phenolic resin organic particles with small particle size and narrow particle size distribution. It also promotes the close packing of the phenolic resin organic particles, which in turn allows the separator to have better heat resistance and air permeability, resulting in better cycle performance of the secondary battery cells.

[0044] Fifthly, this disclosure provides a secondary battery cell, which includes a positive electrode, a negative electrode, and a separator according to the first aspect of this disclosure, wherein the separator is disposed between the positive electrode and the negative electrode.

[0045] In a sixth aspect, this disclosure provides a battery device comprising a plurality of secondary battery cells according to the fifth aspect of this disclosure.

[0046] In a seventh aspect, this disclosure provides an electrical device that includes a secondary battery cell according to the fifth aspect of this disclosure or a battery device according to the sixth aspect of this disclosure. Attached Figure Description

[0047] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are merely some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the drawings without any creative effort.

[0048] Figure 1 shows a schematic diagram of a secondary battery cell provided in some embodiments of this disclosure.

[0049] Figure 2 shows a schematic diagram of an electrical device provided in some embodiments of this disclosure.

[0050] The accompanying drawings are not necessarily drawn to scale. Detailed Implementation

[0051] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the phenolic resin organic particles, their preparation methods, separators, secondary battery cells, battery devices, and electrical devices of this disclosure. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for a full understanding of this disclosure by those skilled in the art and are not intended to limit the subject matter of the claims.

[0052] The "range" disclosed in this disclosure is defined by a lower limit and an upper limit, whereby a given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this disclosure, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0053] Unless otherwise specified, all embodiments and optional embodiments of this disclosure may be combined with each other to form new technical solutions, and such technical solutions should be considered as included in the disclosure of this disclosure.

[0054] Unless otherwise specified, all technical features and optional technical features of this disclosure can be combined to form new technical solutions, and such technical solutions should be considered as included in the disclosure of this disclosure.

[0055] Unless otherwise specified, all steps in this disclosure 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.

[0056] Unless otherwise specified, in this disclosure, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0057] In this disclosure, the terms "multiple" or "a variety" refer to two or more kinds.

[0058] In the description of the embodiments of this disclosure, unless otherwise specified, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0059] Unless otherwise stated, the test temperature for all parameters mentioned in this disclosure is 25°C.

[0060] The secondary battery cell mentioned in the embodiments of this disclosure can independently perform charge and discharge functions. After discharge, it can be recharged to activate the active materials and continue to be used. The secondary battery cell can be cylindrical, cuboid, or other shapes, etc., and the embodiments of this disclosure are not limited to this. Figure 1 shows a cuboid secondary battery cell 5 as an example.

[0061] The secondary battery cells provided in the embodiments of this disclosure may include, but are not limited to, lithium battery cells and sodium battery cells, such as lithium-ion battery cells, sodium-ion battery cells, lithium metal battery cells, sodium metal battery cells, etc.

[0062] The secondary battery cell provided in the embodiments of this disclosure includes an electrode assembly. The electrode assembly can be a wound structure or a stacked structure, and the embodiments of this disclosure are not limited in this regard. The secondary battery cell also includes an outer packaging, which can be used to encapsulate the electrode assembly. The outer packaging can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0063] The battery apparatus mentioned in the embodiments of this disclosure may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple secondary battery cells connected in series, parallel, or mixed connections via a busbar.

[0064] In some embodiments, a battery cell assembly is typically formed by arranging multiple secondary battery cells.

[0065] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple secondary battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple secondary battery cells together with cable ties.

[0066] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0067] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0068] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple secondary battery cells to the housing.

[0069] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0070] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0071] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0072] The technical solutions described in this disclosure are applicable to various electrical devices that use secondary battery cells or battery devices, such as, but not limited to, mobile devices (e.g., mobile phones, tablets, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc. Secondary battery cells and battery devices are used to store or provide electrical energy.

[0073] Figure 2 is a schematic diagram of an example electrical device. This electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0074] In the context of this disclosure, the "phenolic resin organic particles" in the coating of the separator mainly serve to improve heat resistance and have almost no adhesive properties.

[0075] The separator is a crucial component supporting the electrochemical processes of charging and discharging in a secondary battery cell. Commonly used separators are often made of polyolefins; however, polyolefins have poor heat resistance and are prone to softening or melting at high temperatures, which can lead to short circuits in the secondary battery cells. To improve the heat resistance of the separator, a coating is usually applied. Boehmite, alumina, and other inorganic particles are commonly used heat-resistant fillers; however, these fillers have high density and a large mass for the same bulk volume, thus affecting the energy density of the secondary battery cells.

[0076] Based on this, the present disclosure provides a phenolic resin organic particle that, when used in a separator, enables secondary battery cells to possess high energy density, high reliability, and good cycle performance.

[0077] The volume distribution particle size Dv50 of the phenolic resin organic particles disclosed herein is 100nm-800nm, and the particle size distribution (Dv90-Dv10) / Dv50 of the phenolic resin organic particles is 1.4-3.

[0078] Phenolic resin organic particles have low density, and secondary battery cells using them can have higher gravimetric energy density.

[0079] The volumetric particle size distribution (Dv50) of phenolic resin organic particles ranges from 100 nm to 800 nm, and the particle size distribution (Dv90-Dv10) / Dv50 is 1.4-3. Phenolic resin organic particles meeting this particle size distribution can be densely packed. By using phenolic resin organic particles that meet the above parameters in the separator, the phenolic resin organic particles can generate a force to resist the shrinkage of the separator, thereby improving the overall thermal shrinkage of the separator, enhancing its heat resistance, and improving the reliability of the secondary battery cells. Using phenolic resin organic particles that meet the above parameters in the separator can also give the separator better air permeability, which is beneficial for improving the cycle performance of the secondary battery cells.

[0080] Therefore, the phenolic resin organic particles disclosed herein, when used in separator membranes, enable secondary battery cells to possess high energy density, high reliability, and good cycle performance.

[0081] The particle size distribution (Dv90-Dv10) / Dv50 of phenolic resin organic particles is 1.4-3, for example, it can be 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, or any range of the above values.

[0082] Optionally, the particle size distribution (Dv90-Dv10) / Dv50 of the phenolic resin organic particles can be 1.4-2.8, 1.5-2.8, 1.6-2.8, 1.7-2.8, 1.8-2.8, 1.9-2.8, 1.6-2.7, 1.7-2.7, 1.8-2.7, 1.9-2.7, 1.6-2.6, 1.7-2.6, 1.8-2.6, 1.9-2.6, 1.6-2.5, 1.7-2.5, 1.8-2.5, or 1.9-2.5.

[0083] When phenolic resin organic particles have a particle size distribution (Dv90-Dv10) / Dv50 within the above range, their use in separators can improve the separator's heat resistance and air permeability, thereby improving the cycle performance of secondary battery cells.

[0084] The volume distribution particle size Dv50 of phenolic resin organic particles is 100nm-800nm, for example, it can be 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, or any combination of the above values.

[0085] Optionally, the volume distribution particle size Dv50 of the phenolic resin organic particles can be 200nm-600nm, 200nm-550nm, 200nm-500nm, 200nm-450nm, 250nm-600nm, 200nm-600nm, 250nm-500nm, or 250nm-450nm.

[0086] When phenolic resin organic particles with a volume distribution particle size Dv50 within the above range are used in separators, they can give the separators better heat resistance and air permeability, and give secondary battery cells better cycle performance.

[0087] In some embodiments, the volume distribution particle size Dv90 of the phenolic resin organic particles can be 800nm-1800nm, for example, it can be 800nm, 850nm, 900nm, 950nm, 1000nm, 1050nm, 1100nm, 1150nm, 1200nm, 1250nm, 1300nm, 1350nm, 1400nm, 1450nm, 1500nm, 1550nm, 1600nm, 1650nm, 1700nm, 1750nm, 1800nm, or any combination of the above values.

[0088] When phenolic resin organic particles with a volume distribution particle size Dv90 within the above range are used in separator membranes, they are beneficial to improving the consistency of the separator membrane coating.

[0089] Optionally, the volume distribution particle size Dv90 of the phenolic resin organic particles can be 800nm-1600nm, 800nm-1500nm, 800nm-1400nm, 800nm-1300nm, 800nm-1250nm, 800nm-1100nm, 800nm-1050nm, 800nm-1000nm, 800nm-950nm, or 800nm-900nm.

[0090] In some embodiments, the volume distribution particle size Dv10 of the phenolic resin organic particles can be 50nm-200nm, for example, it can be 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 105nm, 110nm, 115nm, 120nm, 125nm, 130nm, 135nm, 140nm, 145nm, 150nm, 155nm, 160nm, 170nm, 180nm, 190nm, 200nm, or any range of the above values.

[0091] When phenolic resin organic particles with a particle size Dv10 within the above-mentioned range are used in separators, the risk of pore blockage in the separator can be reduced.

[0092] Optionally, the volume distribution particle size Dv10 of the phenolic resin organic particles can be 70nm-200nm, 90nm-200nm, 100nm-200nm, 105nm-200nm, 70nm-185nm, 90nm-185nm, 100nm-185nm, 105nm-185nm, 70nm-170nm, 90nm-170nm, 100nm-170nm, 105nm-170nm, 70nm-160nm, 90nm-160nm, 100nm-160nm, or 105nm-160nm.

[0093] Dv10, Dv50, and Dv90 represent the particle sizes corresponding to a cumulative volumetric distribution percentage of 10%, 50%, and 90%, respectively. These values ​​can be determined using a laser particle size analyzer, referring to GB / T 19077-2016. During testing, add 1g of the sample to a clean small beaker and 20ml of deionized water. Sonicate at 53kHz / 120W for 5 minutes to ensure complete dispersion. Turn on the laser particle size analyzer, clean the optical path system, and automatically test the background. Stir the sonicated solution to ensure uniform dispersion, place it in the sample cell as required, and begin measuring the particle size. A MasterSizer 3000 laser particle size analyzer can be used as the testing instrument.

[0094] In some embodiments, the true density of phenolic resin organic particles can be 1.0 g / cm³. 3 -1.4g / cm 3 .

[0095] Currently, the true density of inorganic particles such as boehmite and alumina is typically 2.5 g / cm³. 3 -3.5g / cm 3 The phenolic resin organic particles disclosed herein have a low true density, thereby enabling secondary battery cells using the separator of this disclosure to have a higher mass energy density.

[0096] The phenolic resin organic particles disclosed herein are poorly soluble in both water and organic solvents, such as tetrahydrofuran (THF), dichloromethane (DCM), dimethylformamide (DMF), trichlorobenzene (TCB), and chloroform, at 25°C. They are also insoluble in the mobile phase used in gel permeation chromatography and the molecular weight of the phenolic resin organic particles cannot be determined by gel permeation chromatography.

[0097] In some embodiments, the phenolic resin organic particles are thermosetting propylene resins.

[0098] In some embodiments, phenolic resin organic particles have no melting point.

[0099] The phenolic resin organic particles disclosed herein have no melting point, indicating that the phenolic resin organic particles have good heat resistance and thermal stability. This can better resist the thermal shrinkage of the separator, improve the heat resistance of the separator, and improve the reliability of the secondary battery cell.

[0100] Melting point can be tested as follows: Take an appropriate amount of sample (e.g., 5mg-15mg) and place it in the crucible of a differential scanning calorimeter (DSC), level it, and cover the crucible. Parameter settings: nitrogen atmosphere, purge gas 60mL / min, protective gas 20mL / min; program settings: heat from 25℃ to 200℃ at a heating rate of 10℃ / min, hold for 5min to eliminate thermal history, then cool from 200℃ to -40℃ at a cooling rate of 10℃ / min, and then heat to 300℃ at a heating rate of 10℃ / min. The DSC curve is used to determine whether phenolic resin organic particles have a melting point below 300℃. Phenolic resin organic particles having no melting point means that the DSC curve of the phenolic resin organic particles does not show a melting peak.

[0101] In some embodiments, phenolic resin organic particles have no glass transition temperature below 300°C.

[0102] Phenolic resin organic particles have no glass transition temperature below 300℃, indicating that they have good heat resistance and thermal stability. This allows them to better resist the thermal shrinkage of porous base films, improve the heat resistance of separators, and enhance the reliability of secondary battery cells.

[0103] Glass transition temperature T g The test can be performed as follows: Take an appropriate amount of sample (e.g., 5mg-15mg) and place it in the crucible of the differential scanning calorimeter (DSC), level it, and cover the crucible. Parameter settings: nitrogen atmosphere, purge gas 60mL / min, protective gas 20mL / min; program settings: heat from 25℃ to 200℃ at a heating rate of 10℃ / min, hold for 5min to eliminate thermal history, then cool from 200℃ to -40℃ at a cooling rate of 10℃ / min, and then heat to 300℃ at a heating rate of 10℃ / min. The DSC curve can be used to determine whether phenolic resin organic particles have a glass transition temperature T below 300℃. g .

[0104] Glass transition temperature T g It refers to the transition temperature from the glassy state to the elastic state, which shows a step-like change on the DSC curve.

[0105] Phenolic resin organic particles have no glass transition temperature T below 300℃. g This means that the DSC curve of phenolic resin organic particles does not show a step-like change in the range below 300℃.

[0106] Currently, organic resins obtained through heat curing typically have large particle sizes, requiring them to be first crushed into nano-sized powders for use in the separators of secondary battery cells. Existing processes mainly use physical or chemical methods to crush the large-sized organic resins obtained through heat curing into nano-sized powders, such as air jet milling and ultrasonic milling. However, these crushing methods suffer from low crushing efficiency, high energy consumption, and wide particle size distribution.

[0107] The separator in this embodiment contains phenolic resin organic particles. However, if the size of phenolic resin organic particles is to reach the nanoscale, the processing method is extremely complex, and the particles obtained by conventional processing processes also have the problem of wide particle size distribution.

[0108] Based on this, the present disclosure also provides two methods for preparing phenolic resin organic particles with small particle size and narrow particle size distribution, which can prepare the phenolic resin organic particles provided in the present disclosure.

[0109] [First preparation method]

[0110] A first method for preparing phenolic resin organic particles includes the following steps: providing a primary phenolic resin material; heating and curing the primary phenolic resin material to obtain a phenolic resin material to be crushed; crushing the phenolic resin material to be crushed to obtain crushed phenolic resin organic particles; mixing the crushed phenolic resin organic particles with a first dispersant and water to obtain a sand-milling slurry, followed by sand milling and filtration to obtain phenolic resin organic particles. The first dispersant is a polymeric dispersant. The volume distribution particle size Dv50 of the phenolic resin organic particles is 100nm-800nm, and the particle size distribution (Dv90-Dv10) / Dv50 is 1.4-3.

[0111] The nano-sizing process of phenolic resin materials to be crushed presents certain challenges. Sand milling significantly reduces the size of phenolic resin materials, leading to increased interparticle interactions. Since nanoparticles have a large specific surface area and high surface activity, these interactions may become even more complex, increasing the viscosity of the milling slurry. Furthermore, particles may aggregate during nano-sizing, forming large agglomerates, which also increases the viscosity of the milling slurry and reduces its solids content. If the solids content of the milling slurry is too low, the resulting separator coating slurry will have low solids content and high viscosity. During the drying process, the coating slurry is prone to developing through-pores, resulting in loose packing of phenolic resin particles and reduced heat resistance of the separator. Increasing the amount of milling media or reducing the initial solids content of the milling slurry can alleviate the nano-sizing difficulty to some extent, but this results in low milling efficiency.

[0112] The preparation method provided in this disclosure incorporates a polymeric dispersant during the sand milling process. This polymeric dispersant reduces inter-particle interactions, helping to decrease particle agglomeration and maintain a uniform particle distribution, thereby producing phenolic resin organic particles with small particle size and narrow particle size distribution. Furthermore, the introduction of the polymeric dispersant can increase the solids content of the sand milling slurry while reducing its viscosity, thus improving milling efficiency. It also allows for closer packing of the phenolic resin organic particles, further enhancing the heat resistance of the separating membrane.

[0113] In some embodiments, the first dispersant may include one or more of polyether dispersants, polyacrylic acid dispersants, polycarboxylate dispersants, polyvinylpyrrolidone, and polyethylene glycol.

[0114] Polyether dispersants refer to the general term for polyethers and their derivatives that can act as dispersants.

[0115] Polyacrylic acid dispersants refer to the general term for polyacrylic acid and its derivatives that can act as dispersants.

[0116] Alternatively, polyether dispersants may include polyoxyethylene ethers.

[0117] Optionally, the polyacrylic acid dispersant may include one or both of polyacrylic acid and polymethacrylic acid.

[0118] Optionally, the polycarboxylate dispersant may include one or both of sodium polyacrylate and sodium polymethacrylate.

[0119] Within the aforementioned range, the type of first dispersant can further optimize the solid content and viscosity of the sand milling slurry, which is beneficial for preparing phenolic resin organic particles with small particle size and narrow particle size distribution. It also facilitates the close packing of phenolic resin organic particles, thereby enabling the separator to have better heat resistance and air permeability, and enabling the secondary battery cell to have better cycle performance.

[0120] In some embodiments, the mass of the first dispersant may be 0.01%-2% of the mass of the crushed phenolic resin organic particles, for example, it may be 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, or any range of the above values.

[0121] When the content of the first dispersant is within the above range, the solid content and viscosity of the sand milling slurry can be further optimized, which is beneficial to the preparation of phenolic resin organic particles with small particle size and narrow particle size distribution. It is also beneficial to the close packing of phenolic resin organic particles, which can make the separator membrane have better heat resistance and air permeability, and make the secondary battery cell have better cycle performance.

[0122] Optionally, the mass of the first dispersant may be 0.2%-2%, 0.4%-2%, 0.6%-2%, 0.8%-2%, 0.2%-1.6%, 0.4%-1.6%, 0.6%-1.6%, or 0.8%-1.6% of the mass of the crushed phenolic resin organic particles.

[0123] In some embodiments, the crushing process can employ air jet mills, vibratory mills, mechanical mills, ultrasonic mills, ball mills, etc.

[0124] In some embodiments, the crushing process may include coarse crushing and re-crushing.

[0125] In some embodiments, the phenolic resin material to be crushed is subjected to crushing treatment, and the resulting crushed phenolic resin organic particles have a volume distribution particle size of less than 20 μm.

[0126] In some embodiments, the sanding process may be performed using a sand mill.

[0127] In some embodiments, the grinding speed can be 500rpm-2000rpm, for example, 500rpm, 600rpm, 700rpm, 800rpm, 900rpm, 1000rpm, 1100rpm, 1200rpm, 1300rpm, 1400rpm, 1500rpm, 1600rpm, 1700rpm, 1800rpm, 1900rpm, 2000rpm, or any range of the above values.

[0128] Higher rotation speeds are beneficial for obtaining phenolic resin organic particles with smaller particle size and narrower particle size distribution.

[0129] In some embodiments, the temperature of the sanding process can be 20°C-30°C.

[0130] In some embodiments, the abrasive media may include glass beads or zirconia balls.

[0131] In some embodiments, the diameter of the abrasive media can be 0.1 mm to 2 mm, and optionally 0.4 mm to 1.5 mm. Smaller abrasive media are advantageous for obtaining phenolic resin organic particles with smaller particle size and narrower particle size distribution.

[0132] In some embodiments, the filling rate of the grinding media can be between 60% and 85%. This allows the grinding media to fully contact the phenolic resin organic particles, improving the grinding effect and facilitating the production of phenolic resin organic particles with smaller particle size and narrower particle size distribution.

[0133] In some embodiments, the preparation method further includes a sieving step and a demagnetization step after the sand milling process.

[0134] Phenolic resin organic particles are obtained by heating and curing methyl phenolic resin materials, thus exhibiting good heat resistance.

[0135] In some embodiments, heat curing can be a one-step heat curing or a two-step heat curing.

[0136] Alternatively, the heat curing process can be a two-step process. This results in phenolic resin organic particles with better heat resistance.

[0137] In some embodiments, heat curing can be a one-step heat curing, and the temperature of the one-step heat curing can be 185℃-280℃, for example, 185℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, or any range of the above values.

[0138] Optionally, the temperature for one-step heat curing can be 200℃-280℃, 210℃-280℃, 220℃-280℃, 200℃-270℃, 210℃-270℃, or 220℃-270℃.

[0139] Optionally, the curing time for one-step heating can be 3h-8h, for example, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, or any range of the above values. Optionally, the curing time for one-step heating can be 4h-8h.

[0140] In some embodiments, heat curing can be a two-step heat curing process, with the first step heat curing temperature being 90℃-180℃ and the second step heat curing temperature being 190℃-290℃.

[0141] The two-step heating and curing process allows for more complete curing of methyl phenolic resin materials, thereby giving the phenolic resin organic particles better heat resistance and oxidation resistance.

[0142] The temperature for the first step of heating and curing is 90℃-180℃, for example, it can be 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, or any combination of the above values. Optionally, the temperature for the first step of heating and curing can be 90℃-160℃, 100℃-160℃, 110℃-160℃, 90℃-150℃, 100℃-150℃, or 110℃-150℃.

[0143] The temperature of the first step of heating and curing is within the above range, which also helps to eliminate small molecule groups and easily oxidized groups, so that the obtained phenolic resin organic particles have better oxidation resistance.

[0144] The second step of heat curing takes place at a temperature of 190℃-290℃, for example, 180℃, 185℃, 190℃, 195℃, 200℃, 205℃, 210℃, 215℃, 220℃, 225℃, 230℃, 235℃, 240℃, 245℃, 250℃, 255℃, 260℃, 265℃, 270℃, 275℃, 280℃, 285℃, 290℃, or any combination of the above values. Optionally, the second step of heat curing can take place at 210℃-290℃, 210℃-280℃, or 210℃-270℃.

[0145] The second step of heating and curing, within the above-mentioned temperature range, also helps to eliminate small molecule groups and easily oxidized groups, giving the resulting phenolic resin organic particles better oxidation resistance.

[0146] Optionally, the heating and curing time for the first step can be 1 hour to 5 hours, for example, 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, 4 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours, 5 hours, or any range of the above values.

[0147] Optionally, the curing time in the second step can be 1 hour to 6 hours, for example, 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, 4 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours, 5 hours, 5.5 hours, 6 hours, or any range of the above values.

[0148] When the two-step heating and curing time is within the above range, the heat resistance and oxidation resistance of phenolic resin organic particles can be improved.

[0149] In some embodiments, the atmosphere for heating and curing can be an oxygen-containing atmosphere or an inert atmosphere.

[0150] Heating and curing in an oxygen-containing atmosphere can improve the oxidation resistance of phenolic resin organic particles. Curing in an oxygen-containing atmosphere allows for the premature oxidation of easily oxidized groups in methyl phenolic resin materials. At this time, the phenol structure will be oxidized to a benzoquinone structure, which is less susceptible to oxidation, thereby further improving the oxidation resistance of phenolic resin organic particles.

[0151] An oxygen-containing atmosphere may include oxygen and an inert gas. Optionally, the inert gas may include, but is not limited to, one or more of nitrogen, argon, and helium.

[0152] Optionally, the volume fraction of oxygen in the oxygen-containing atmosphere can be 5%-50%. More preferably, the volume fraction of oxygen in the oxygen-containing atmosphere can be 10%-30%.

[0153] In some embodiments, the heating and curing atmosphere can be air. This can reduce costs.

[0154] Amorphous phenolic resins are commercially available or synthesized using methods known in the art. In some embodiments, the preparation method of amorphous phenolic resins includes the following steps: reacting a phenolic compound and an aldehyde compound under the catalysis of an alkaline substance to obtain the amorphous phenolic resin.

[0155] Optionally, the alkaline substance may include one or more of ammonia, NaOH, and Na2CO3.

[0156] Optionally, phenolic compounds may include one or more of phenol, hydroquinone, resorcinol, catechol, cresol, and cashew nut shellol.

[0157] Optionally, aldehyde compounds may include one or more of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, glyoxal, and furfural.

[0158] [Second preparation method]

[0159] A second method for preparing phenolic resin organic particles includes the following steps: providing a foaming agent and a primary phenolic resin material; mixing the foaming agent and the primary phenolic resin material uniformly, followed by heating and curing to obtain phenolic resin material to be crushed; crushing the phenolic resin material to be crushed to obtain crushed phenolic resin organic particles; and milling the crushed phenolic resin organic particles to obtain phenolic resin organic particles. The volumetric particle size distribution (Dv50) of the phenolic resin organic particles is 100 nm-800 nm, and the particle size distribution (Dv90-Dv10) / Dv50 is 1.4-3.

[0160] In the process of heating and curing phenolic resin materials, a foaming agent is added. During the curing process, the foaming agent can generate gas through decomposition or volatilization, causing the phenolic resin material to expand and form foam. This alters the structure and properties of the phenolic resin material. The gas can diffuse through the membrane wall of the phenolic resin material, inhibiting the expansion of the cured cross-linked network. This allows the phenolic resin material to be easily processed through crushing and milling to obtain phenolic resin organic particles with small particle size and narrow particle size distribution. Therefore, the preparation method provided in this disclosure can efficiently obtain phenolic resin organic particles with small particle size and narrow particle size distribution.

[0161] In addition, the preparation method provided in this embodiment is simple and does not require complex operations, thus having low production costs.

[0162] In some embodiments, the mass of the foaming agent can be 1%-20% of the mass of the methyl phenolic resin material, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or any range of the above values.

[0163] Optionally, the mass of the foaming agent can be 2%-20%, 2%-18%, 2%-16%, 2%-14%, or 2%-12% of the mass of the methyl phenolic resin material.

[0164] An appropriate amount of foaming agent is beneficial for obtaining phenolic resin organic particles with small particle size and narrow particle size distribution.

[0165] Foaming agents can include physical foaming agents and / or chemical foaming agents. Physical foaming agents do not undergo chemical changes during use; they achieve foaming through changes in their physical state. Chemical foaming agents are substances that produce gas and thus foam through chemical changes during the foaming process.

[0166] In some embodiments, the foaming agent may include organic foaming agents and / or inorganic foaming agents.

[0167] Optionally, the foaming agent includes an inorganic foaming agent. Inorganic foaming agents are relatively cheaper than organic foaming agents and produce gas with stronger permeability, making it easier to diffuse through the membrane wall. This makes the cured phenolic resin easier to crush and sand.

[0168] Optionally, the inorganic foaming agent may include one or more of ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, potassium bicarbonate, and sodium carbonate.

[0169] Optionally, the organic foaming agent may include one or more of the following: low-boiling-point aliphatic hydrocarbons, low-boiling-point halogenated aliphatic hydrocarbons, azo compounds, hydrazine compounds, and nitroso compounds.

[0170] Optionally, the aliphatic hydrocarbon may include one or more of n-pentane, isopentane, cyclopentane, hexane, isohexane, propane, and butane.

[0171] Alternatively, the halogenated aliphatic hydrocarbon may include one or more of dichloromethane, 1-chloro-3,3,3-trifluoropropene, and Freon.

[0172] Optionally, the azo compounds may include one or more of azodicarbonamide, azobisisobutyronitrile, isopropyl azodicarbonate, diethyl azodicarbonate, and dimethyl azobisisobutyronate.

[0173] Optionally, the hydrazine compound may include one or more of 4,4-disulfonylhydrazine diphenyl ether, p-benzenesulfonylhydrazine, 3,3-disulfonylhydrazine diphenyl sulfone, 4,4-diphenyl disulfonylhydrazine, 1,3-benzene disulfonylhydrazine, and 1,4-benzene disulfonylhydrazine.

[0174] Alternatively, the nitroso compound may include N,N-dinitrospentamethylenetetramine.

[0175] In some embodiments, the crushing process can employ air jet mills, vibratory mills, mechanical mills, ultrasonic mills, ball mills, etc.

[0176] In some embodiments, the sanding process may be performed using a sand mill.

[0177] In some embodiments, the grinding speed can be 500rpm-2000rpm, for example, 500rpm, 600rpm, 700rpm, 800rpm, 900rpm, 1000rpm, 1100rpm, 1200rpm, 1300rpm, 1400rpm, 1500rpm, 1600rpm, 1700rpm, 1800rpm, 1900rpm, 2000rpm, or any range of the above values.

[0178] In some embodiments, the temperature of the sanding process can be 20°C-30°C.

[0179] In some embodiments, the abrasive media may include glass beads or zirconia balls.

[0180] In some embodiments, the diameter of the abrasive media can be 0.1 mm to 2 mm, and optionally 0.4 mm to 1.5 mm. Smaller abrasive media are advantageous for obtaining phenolic resin organic particles with smaller particle size and narrower particle size distribution.

[0181] In some embodiments, the filling rate of the grinding media can be between 60% and 85%. This allows the grinding media to fully contact the phenolic resin organic particles, improving the grinding effect and facilitating the production of phenolic resin organic particles with smaller particle size and narrower particle size distribution.

[0182] In some embodiments, a second dispersant is added during the sand milling process of the crushed phenolic resin organic particles. This is beneficial for obtaining phenolic resin organic particles with smaller particle size and narrower particle size distribution.

[0183] Optionally, the second dispersant may include a polymeric dispersant.

[0184] Optionally, the second dispersant may include one or more of polyether dispersants, polyacrylic acid dispersants, polycarboxylate dispersants, polyvinylpyrrolidone, and polyethylene glycol. Polyether dispersants refer to the general term for polyethers and their derivatives that can act as dispersants. Polyacrylic acid dispersants refer to the general term for polyacrylic acid and its derivatives that can act as dispersants. Optionally, polyether dispersants may include polyoxyethylene ethers. Optionally, polyacrylic acid dispersants may include one or both of polyacrylic acid and polymethacrylic acid. Optionally, polycarboxylate dispersants may include one or both of sodium polyacrylate and sodium polymethacrylate.

[0185] The second dispersant, within the aforementioned range, can optimize the solid content and viscosity of the grinding slurry. This facilitates the preparation of phenolic resin organic particles with small particle size and narrow particle size distribution. It also promotes the close packing of phenolic resin organic particles, thereby enabling the separator to have better heat resistance and air permeability, and giving the secondary battery cell better cycle performance.

[0186] In some embodiments, the mass of the second dispersant may be 0.01%-2% of the mass of the crushed phenolic resin organic particles, for example, it may be 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, or any range of the above values.

[0187] When the content of the second dispersant is within the above range, it can optimize the solid content and viscosity of the sand mill slurry. This is beneficial for preparing phenolic resin organic particles with small particle size and narrow particle size distribution. It is also beneficial for the close packing of phenolic resin organic particles, which can make the separator membrane have better heat resistance and air permeability, and make the secondary battery cell have better cycle performance.

[0188] Optionally, the mass of the second dispersant can be 0.2%-2%, 0.4%-2%, 0.6%-2%, 0.8%-2%, 1%-2%, 0.2%-1.6%, 0.4%-1.6%, 0.6%-1.6%, 0.8%-1.6%, or 1%-1.6% of the mass of the crushed phenolic resin organic particles.

[0189] In some embodiments, the preparation method further includes sieving and demagnetizing steps after sand milling.

[0190] The heating and curing process for methyl phenolic resin materials is the same as the first preparation method described above, and will not be repeated here.

[0191] This disclosure also provides a separator membrane. The separator membrane includes a porous base membrane and a coating located on at least one side of the porous base membrane. The coating includes an adhesive and phenolic resin organic particles of this disclosure or phenolic resin organic particles prepared by the method of this disclosure.

[0192] Both the porous base membrane and the coating have a porous structure, which gives the separator good air permeability and facilitates ion passage. The phenolic resin organic particles in the coating are interconnected and fixed by a binder, and the gaps between the phenolic resin organic particles can form a porous structure.

[0193] In some embodiments, the mass content of phenolic resin organic particles in the coating may be 50%-99% based on the total mass of the coating.

[0194] Optionally, the mass content of phenolic resin organic particles in the coating can be 60%-99%, 70%-99%, 80%-99%, 85%-99%, 88%-99%, 80%-97%, 85%-97%, 88%-97%, 80%-95%, 85%-95%, or 88%-95%.

[0195] In some embodiments, the binder in the coating may include, but is not limited to, one or more of the following: polyacrylate binders, nitrile rubber binders, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0196] In some embodiments, the coating may also include a dispersant, such as, but not limited to, polyacrylic acid dispersants or carboxymethyl cellulose dispersants. As an example, the dispersant may include, but is not limited to, one or more of sodium carboxymethyl cellulose, sodium polyacrylate, and ammonium polyacrylate.

[0197] In some embodiments, the separator may also include polymer binder particles.

[0198] The "polymer binder particles" in the porous coating of the separator membrane play a role in improving the adhesion between the separator membrane and the electrode, but they have virtually no high-temperature resistance.

[0199] In some embodiments, polymer binder particles may be embedded in phenolic resin organic particles and form protrusions on the coating surface.

[0200] In other embodiments, the coating of the separator includes a heat-resistant layer and an adhesive layer. The heat-resistant layer is disposed on a porous base membrane, and the adhesive layer is disposed on at least a portion of the surface of the heat-resistant layer on the side away from the porous base membrane. Phenolic resin organic particles are disposed in the heat-resistant layer, and polymer adhesive particles are disposed in the adhesive layer.

[0201] In some other embodiments, the coating of the separator includes a heat-resistant layer and an adhesive layer. The heat-resistant layer is disposed on one side of the porous base membrane, and the adhesive layer is disposed on at least a portion of the surface of the other side of the porous base membrane. Phenolic resin organic particles are disposed in the heat-resistant layer, and polymer adhesive particles are disposed in the adhesive layer.

[0202] In some embodiments, the average particle size of the polymer binder particles can be 6 μm-18 μm.

[0203] In some embodiments, the polymer binder particles may include vinylidene fluoride polymer particles, such as polyvinylidene fluoride (PVDF) particles and / or copolymer particles of vinylidene fluoride monomer and comonomer.

[0204] Comonomers may include at least one of olefin monomers, fluorinated olefin monomers, chlorinated olefin monomers, acrylate monomers, acrylic monomers, and fluoroether monomers.

[0205] Optionally, the comonomer may include at least one of the following: trifluoroethylene, trifluorochloroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoro(alkyl vinyl) ether (e.g., perfluoro(methyl vinyl) ether, perfluoro(ethyl vinyl) ether, perfluoro(propyl vinyl) ether), perfluoro(1,3-m-dioxacyclopentene), and perfluoro(2,2-dimethyl-1,3-m-dioxacyclopentene).

[0206] In some embodiments, the coating thickness can be 0.5 μm-5 μm. The coating thickness refers to the thickness of the coating on one side of the porous base film. Optionally, the coating thickness can be 0.5 μm-4 μm, 0.5 μm-3 μm, 0.5 μm-2 μm, 0.8 μm-4 μm, 0.8 μm-3 μm, or 0.8 μm-2 μm.

[0207] In some embodiments, the areal density of the coating may be 0.45 g / m³. 2 -4.5g / m 2 .

[0208] In some embodiments, the porous base membrane may comprise a membrane or nonwoven web selected from any one or at least two of the following: polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymer, polyphenylene sulfide, and polyvinylnaphthalene.

[0209] Porous base membranes can be single-layer thin films or multi-layer composite thin films. When a porous base membrane is a multi-layer composite thin film, the materials of each layer can be the same or different.

[0210] In some embodiments, the thickness of the porous base film can be 4μm-12μm, and optionally 4μm-9μm.

[0211] In some embodiments, the porosity of the porous base membrane can be 25%-60%, optionally 28%-50%.

[0212] In some embodiments, the ratio of the volume distribution particle size Dv50 of the phenolic resin organic particles to the average pore size of the porous base membrane can be greater than or equal to 1.5. Optionally, the ratio of the volume distribution particle size Dv50 of the phenolic resin organic particles to the average pore size of the porous base membrane can be greater than or equal to 2, or greater than or equal to 2.5.

[0213] The volume distribution particle size Dv50 of phenolic resin organic particles has the same unit, such as nm, as the average pore size of porous base membranes.

[0214] This can reduce pore blockage and improve the air permeability and ion conduction properties of the separator.

[0215] In some embodiments, the average pore size of the porous base film can be 25 nm to 82 nm.

[0216] The average pore size of the porous membrane can be measured using a capillary porosity analyzer (bubble point method). An exemplary testing method is as follows: Take a circular sample with a diameter of 25 mm, and drop 3-5 drops of wetting solution onto it. After the sample is completely wetted, place it in a mold. Then, use an inert gas (such as nitrogen) to compress the wetting solution in the pores of the sample. The compression pressure and flow rate are inversely proportional to the pore size. The average pore size of the sample is obtained through software sampling and pressure-pore size conversion analysis. The testing instrument can be a PMI CFP 1500 pore size analyzer, with a testing pressure ranging from 100 psi to 350 psi.

[0217] In some embodiments, the thickness of the separator can be 5μm-14μm, optionally 5μm-12μm or 6μm-12μm. This is beneficial for improving the energy density of the secondary battery cell.

[0218] In some embodiments, the longitudinal (MD) heat shrinkage rate of the separator film can be less than or equal to 2% when heated at a constant temperature of 130°C for 1 hour.

[0219] In some embodiments, the transverse (TD) heat shrinkage rate of the separator film can be less than or equal to 2% after being heated at a constant temperature of 130°C for 1 hour.

[0220] In some embodiments, the air permeability of the separator membrane can be 160s / 100mL-230s / 100mL, optionally 160s / 100mL-220s / 100mL, 160s / 100mL-215s / 100mL, 160s / 100mL-210s / 100mL, 160s / 100mL-205s / 100mL, 160s / 100mL-200s / 100mL, 170s / 100mL-220s / 100mL, 170s / 100mL- 215s / 100mL, 170s / 100mL-210s / 100mL, 170s / 100mL-205s / 100mL, 170s / 100mL-200s / 100mL, 180s / 100mL-220s / 100mL, 180s / 100mL-215s / 100mL, 180s / 100mL-210s / 100mL, 180s / 100mL-205s / 100mL, 180s / 100mL-200s / 100mL.

[0221] It should be noted that the coating parameters of the above-mentioned separators are coating parameters for one side of the porous base membrane. When the coating is applied to both sides of the porous base membrane, if the coating parameters of either side meet the requirements of this disclosure, it is considered to fall within the protection scope of this disclosure.

[0222] The separator membrane can be prepared according to methods known in the art.

[0223] In some embodiments, a slurry comprising phenolic resin organic particles and a binder can be coated on at least one side of a porous base membrane, and after drying, a separation membrane is obtained.

[0224] In some embodiments, the slurry may further include polymer binder particles, which, after drying, are embedded in phenolic resin organic particles and form protrusions on the coating surface.

[0225] In some embodiments, the method for preparing the separator membrane may include: applying a heat-resistant layer slurry comprising phenolic resin organic particles and a binder to at least one side of a porous base membrane, and drying it to form a heat-resistant layer; and applying an adhesive layer slurry comprising polymer binder particles and a binder to at least a portion of the surface of the heat-resistant layer, and drying it to obtain the separator membrane.

[0226] In some embodiments, the method for preparing the separator membrane may include: coating a heat-resistant slurry comprising phenolic resin organic particles and a binder onto one side of a porous base membrane, and coating an adhesive layer slurry comprising polymer binder particles and a binder onto at least a portion of the surface of the other side of the porous base membrane, and drying the slurry to obtain the separator membrane.

[0227] In some embodiments, the solvent for the slurry may be water, such as deionized water.

[0228] In some embodiments, the slurry may also include other components, such as dispersants and / or wetting agents.

[0229] This disclosure also provides a secondary battery cell. The secondary battery cell includes the separator provided in this disclosure. This allows the secondary battery cell to possess high energy density, high reliability, and good cycle performance.

[0230] A secondary battery cell also includes a positive electrode, a negative electrode, and an electrolyte, with a separator disposed between the positive and negative electrodes. The positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process.

[0231] The secondary battery cells disclosed herein may include, but are not limited to, lithium battery cells, sodium battery cells, etc. The composition of the positive electrode, negative electrode and electrolyte may differ depending on the type of secondary battery cell.

[0232] [Positive electrode plate]

[0233] In some embodiments, the positive electrode may include a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector and comprising a positive electrode active material. For example, the positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0234] Taking a lithium-ion battery cell as an example, the positive electrode active material may include, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their respective modified compounds. Examples of lithium-containing phosphates may include, but are not limited to, lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their respective modified compounds. In some embodiments, to further improve the energy density of the secondary battery cell, the positive electrode active material may include materials with the general formula Li a Nib Co c M d O e A f One or more of lithium transition metal oxides and their modified compounds. 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes but is not limited to one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes but is not limited to one or more of N, F, S and Cl.

[0235] As an example, the positive electrode active material may include, but is not limited to, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 Co 0.1 Al 0.05 One or more of O2, LiFePO4, and LiMnPO4.

[0236] During the charging and discharging process, Li undergoes insertion / extraction and consumption in a single secondary battery cell, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this disclosure, the molar Li content represents the initial state of the material, i.e., the state before feeding. When the positive electrode active material is applied to a secondary battery cell, the molar Li content changes after charge-discharge cycles. Similarly, in the examples of positive electrode active materials in this disclosure, the molar O content is only a theoretical value. Lattice oxygen release causes changes in the molar O content, and the actual molar O content will also fluctuate.

[0237] Taking sodium-ion battery cells as an example, the positive electrode active material can be one or more of the following, including but not limited to sodium-containing transition metal oxides, polyanionic materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian blue materials. For example, the positive electrode active material can be, but is not limited to, NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, and NaNi 1 / 2 Ti 1 / 2 O2, NaNi1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue materials, with the general formula X p M' q (PO4) r O x Y 3-x One or more of the materials. In general formula X p M' q (PO4) r O x Y 3-x In this case, 0 < p ≤ 4, 0 < q ≤ 2, 1 ≤ r ≤ 3, 0 ≤ x ≤ 2, and X includes, but is not limited to, H. + Li + Na + K + and NH4 + One or more of the following, M' is a transition metal cation, optionally including but not limited to one or more of V, Ti, Mn, Fe, Co, Ni, Cu and Zn, and Y is a halide anion, optionally one or more of F, Cl and Br.

[0238] The modified compounds for the positive electrode active materials of the aforementioned lithium battery cells and sodium battery cells can be obtained by doping and / or surface coating modifications of the positive electrode active materials.

[0239] In some embodiments, the positive electrode film layer may further include a positive electrode conductive agent. As an example, the positive electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0240] In some embodiments, the positive electrode film layer may further include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0241] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include, but is not limited to, one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0242] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing positive electrode active materials, positive electrode conductive agents, positive electrode binders, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to this.

[0243] [Negative electrode plate]

[0244] In some embodiments, the negative electrode sheet may include a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector and comprising a negative electrode active material. For example, the negative current collector has two surfaces opposite each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative current collector.

[0245] The negative electrode active material may be any material known in the art for use in secondary battery cells. As an example, the negative electrode active material may include, but is not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may include, but are not limited to, one or more of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include, but are not limited to, one or more of elemental tin, tin oxide, and tin alloys.

[0246] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. As an example, the negative electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0247] In some embodiments, the negative electrode film layer may further include a negative electrode binder. As an example, the negative electrode binder may include, but is not limited to, one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0248] In some embodiments, the negative electrode film layer may also include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0249] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, copper foil may be used. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include, but is not limited to, one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0250] The negative electrode film is typically formed by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is usually formed by dispersing the negative electrode active material, negative electrode conductive agent, negative electrode binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0251] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet also includes a conductive undercoat layer (e.g., composed of a conductive agent and a binder) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector.

[0252] In some embodiments, the negative electrode sheet can be made of foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, foamed carbon, etc. When foamed metal is used as the negative electrode sheet, the surface of the foamed metal may or may not contain a negative electrode active material.

[0253] [Electrolytes]

[0254] The electrolyte plays a role in conducting ions between the positive and negative electrode plates.

[0255] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and an organic solvent.

[0256] Taking a lithium battery cell as an example, the electrolyte salt may include, but is not limited to, one or more of the following: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0257] Taking sodium battery cells as an example, the electrolyte salt may include, but is not limited to, one or more of the following: sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium difluorosulfonyl imide (NaFSI), sodium difluoromethanesulfonyl imide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorooxalate borate (NaDFOB), sodium dioxalate borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorodioxalate phosphate (NaDFOP), and sodium tetrafluorooxalate phosphate (NaTFOP).

[0258] In some embodiments, the organic solvent may include, but is not limited to, one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl ester carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulfone (ESE), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ether.

[0259] In some embodiments, the electrolyte may also include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the secondary battery cell, such as additives that improve overcharge performance, additives that improve high-temperature performance, additives that improve low-temperature performance, etc.

[0260] Optionally, the additive may include one or more of fluoroethylene carbonate (FEC), vinylene carbonate (VC), 1,3-propanesulfonate lactone (PS), and ethylene sulfate (DTD).

[0261] Methods for preparing secondary battery cells are well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a secondary battery cell. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with the aforementioned electrolyte. After vacuum sealing, settling, and formation processes, a secondary battery cell is obtained.

[0262] Example

[0263] The following embodiments describe the disclosure of this disclosure in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0264] Weigh commercially available phenolic resin material (containing phenol and formaldehyde) and sodium bicarbonate (a foaming agent) at a mass ratio of 100:15, mix and stir evenly, and pour into a polytetrafluoroethylene tray. Place the mixture in a curing oven with an air atmosphere and a temperature of 220°C, and maintain this temperature for 4 hours. Remove the cured phenolic resin material, allow it to cool naturally in air, then crush it using an air jet mill, mix it with water for sand milling, sieve it, and demagnetize it to obtain phenolic resin organic particles #1.

[0265] Weigh commercially available phenolic resin material (containing phenol and formaldehyde) and sodium bicarbonate (a foaming agent) at a mass ratio of 100:20, mix them thoroughly, and pour the mixture into a polytetrafluoroethylene tray. Place the mixture in a curing oven with an air atmosphere and a temperature of 220°C, and maintain this temperature for 4 hours. Remove the cured phenolic resin material, allow it to cool naturally in the air, then crush it using an air jet mill, mix it with water for sand milling, sieve it, and demagnetize it to obtain phenolic resin organic particles #2.

[0266] Weigh commercially available phenolic resin material (containing phenol and formaldehyde) and sodium bicarbonate (a foaming agent) at a mass ratio of 100:10, mix them thoroughly, and pour the mixture into a polytetrafluoroethylene tray. Place the mixture in a curing oven with an air atmosphere and a temperature of 220°C, and maintain this temperature for 4 hours. Remove the cured phenolic resin material, allow it to cool naturally in the air, then crush it using an air jet mill, mix it with water for sand milling, sieve it, and demagnetize it to obtain phenolic resin organic particles #3.

[0267] Weigh commercially available phenolic resin material (containing phenol and formaldehyde) and sodium bicarbonate (a foaming agent) at a mass ratio of 100:5, mix and stir evenly, and pour into a polytetrafluoroethylene tray. Place the mixture in a curing oven with an air atmosphere and a temperature of 220°C, and maintain this temperature for 4 hours. Remove the cured phenolic resin material, allow it to cool naturally in the air, then crush it using an air jet mill, mix it with water for sand milling, sieve it, and demagnetize it to obtain phenolic resin organic particles #4.

[0268] Weigh commercially available phenolic resin material (containing phenol and formaldehyde) and sodium bicarbonate (a foaming agent) at a mass ratio of 100:1, mix them thoroughly, and pour the mixture into a polytetrafluoroethylene tray. Place the mixture in a curing oven with an air atmosphere and a temperature of 220°C, and maintain this temperature for 4 hours. Remove the cured phenolic resin material, allow it to cool naturally in the air, then crush it using an air jet mill, mix it with water for sand milling, sieve it, and demagnetize it to obtain phenolic resin organic particles #5.

[0269] Weigh commercially available phenolic resin material (containing phenol and formaldehyde) and foaming agent azodicarbonamide at a mass ratio of 100:15, mix and stir evenly, and pour into a polytetrafluoroethylene tray. Place the mixture in a curing oven with an air atmosphere and a temperature of 220°C, and maintain this temperature for 4 hours. Remove the cured phenolic resin material, allow it to cool naturally in the air, then crush it using an air jet mill, mix it with water for sand milling, sieve it, and demagnetize it to obtain phenolic resin organic particles #6.

[0270] A commercially available phenolic resin material made from phenol and formaldehyde was placed in a curing oven with an air atmosphere and a temperature of 120°C. The curing process was maintained at this temperature for 4 hours. The cured phenolic resin material was then removed, allowed to cool naturally in the air, and then crushed using an air jet mill. It was then mixed with water for sand milling, sieved, and demagnetized to obtain phenolic resin organic particles D1#.

[0271] A commercially available phenolic resin material made from phenol and formaldehyde was placed in a curing oven with an air atmosphere and a temperature of 120°C. The curing process was maintained at this temperature for 4 hours. The cured phenolic resin material was then removed, allowed to cool naturally in the air, and then crushed using an air jet mill. It was then mixed with water for sand milling, sieved, and demagnetized to obtain phenolic resin organic particles D2#.

[0272] Phenolic resin organic particles 1# to 6# and D1# were subjected to sand milling under the same conditions: the sand mill speed was 1100 rpm, the sand milling time was 4 hours, the temperature was 25℃, and the sand milling media were zirconia balls with a diameter of 0.8 mm to 1 mm.

[0273] The sand milling time for phenolic resin organic particles D2# is shorter than that for phenolic resin organic particles D1#. The sand mill speed is 1100 rpm, the sand milling time is 2.5 h, the temperature is 25℃, and the sand milling media are zirconia balls with a diameter of 0.8 mm-1 mm.

[0274] Commercially available phenolic resin material, consisting of phenol and formaldehyde, was placed in a curing oven with an air atmosphere and a temperature of 220℃, and cured for 4 hours. The cured phenolic resin material was then removed and allowed to cool naturally in air before being crushed using an air jet mill. Next, 2 kg of the crushed phenolic resin material, 10 g of polyoxyethylene ether, and 1 kg of deionized water were added to a 5L sand mill and mixed thoroughly before sand milling. The mill speed was maintained at 1500 rpm, the temperature at 25℃, and the milling media were zirconia balls with a diameter of 0.8 mm-1 mm. After sand milling for 2 hours, deionized water was added to adjust the viscosity. Sand milling continued for 3 hours to obtain a slurry with a viscosity of 2620 mPa·s and a solid content of 23%. After filtration, the slurry underwent sieving and demagnetization to obtain phenolic resin organic particles #7.

[0275] Performance testing of phenolic resin organic particles

[0276] (1) Melting point test of phenolic resin organic particles

[0277] Take an appropriate amount of sample (e.g., 5mg-15mg) and place it in the crucible of the differential scanning calorimeter (DSC). Level the sample and cover the crucible. Parameter settings: nitrogen atmosphere, purge gas 60mL / min, protective gas 20mL / min; temperature rise program: heating rate 10℃ / min, temperature range 35℃-300℃. Determine whether the phenolic resin organic particles have a melting point using the DSC curve.

[0278] (2) Particle size test

[0279] Dv10, Dv50, and Dv90 represent the particle sizes corresponding to a cumulative volumetric distribution percentage of 10%, 50%, and 90%, respectively. The testing standard is based on GB / T 19077-2016. The testing instrument is a MasterSizer 3000 laser particle size analyzer. During testing, 1g of the sample to be tested is added to a clean small beaker, followed by 20ml of deionized water. The sample is sonicated at 53kHz / 120W for 5 minutes to ensure complete dispersion. The laser particle size analyzer is then turned on, and after cleaning the optical path system, the background is automatically measured. The sonicated solution is stirred to ensure uniform dispersion, then placed into the sample cell as required, and particle size measurement begins.

[0280] The phenolic resin organic particles 1# to 7# prepared above meet the following characteristics: the phenolic resin organic particles are thermosetting propylene resins with no melting point.

[0281] Next, the phenolic resin organic particles prepared above were used in the separator to verify their impact on the performance of the separator and the secondary battery cells.

[0282] The manufacturing process of a secondary battery cell is as follows.

[0283] Preparation of the separating membrane: A commercially available 7μm thick polyethylene microporous membrane was used as the porous base membrane; the phenolic resin organic particles, dispersant sodium carboxymethyl cellulose, and binder polyacrylate prepared above were mixed evenly in deionized water at a solid mass ratio of 90:2:8 to obtain a slurry; the slurry was then mixed at 2.2 g / m 2 The loading amount is uniformly coated on both surfaces of the porous base membrane, and the solvent is removed by drying to obtain the isolation membrane.

[0284] Preparation of positive electrode sheet: The positive electrode active material LiFePO4, the positive electrode binder polyvinylidene fluoride (PVDF), and the positive electrode conductive agent carbon black are added to N-methylpyrrolidone (NMP) in a mass ratio of 97:2:1. After thorough stirring and mixing, a positive electrode slurry is prepared. The positive electrode slurry is uniformly coated on the positive electrode current collector aluminum foil, and then dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0285] Preparation of negative electrode sheet: The negative electrode active material artificial graphite, the negative electrode conductive agent acetylene black, the negative electrode binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose are added to deionized water in a mass ratio of 96.0:1.4:1.5:1.1 and stirred thoroughly to prepare a negative electrode slurry. The negative electrode slurry is uniformly coated on the negative electrode current collector copper foil, and then dried, cold-pressed, and slit to obtain the negative electrode sheet.

[0286] Electrolyte preparation: Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 3:7 at 25°C to obtain a mixed solvent. LiPF6 and vinylene carbonate (VC) were then dissolved in this mixed solvent to obtain the electrolyte. The concentration of LiPF6 was 1 mol / L. The mass fraction of VC was 3%, based on the mass of the electrolyte.

[0287] Preparation of secondary battery cells: The positive electrode sheet, separator, and negative electrode sheet are stacked and wound in sequence and hot-pressed to form an electrode assembly; the electrode assembly is placed in a hard outer packaging, the electrolyte prepared above is added, and after processes such as encapsulation, standing, formation, and aging, a secondary battery cell is obtained.

[0288] Performance testing

[0289] (1) Thermal shrinkage rate test of the separator film

[0290] For testing the heat shrinkage rate of the release liner, please refer to GB / T 36363-2018.

[0291] Cut the release film into samples with a width of 50mm and a length of 100mm using a punching machine. Take 5 parallel samples and place them on A4 paper. Then place the A4 paper containing the samples on corrugated paper with a thickness of 1mm to 5mm.

[0292] Set the temperature of the forced-air drying oven to 130℃. After the temperature reaches the set temperature and stabilizes for 60 minutes, place the A4 paper placed on the corrugated paper into the forced-air drying oven and start timing. After the set time (1 hour in this disclosure) is reached, measure the length and width of the isolation film, and mark the values ​​as a and b respectively.

[0293] Calculation of heat shrinkage rate: Longitudinal (MD) heat shrinkage rate = [(100-a) / 100]×100%, Transverse (TD) heat shrinkage rate = [(50-b) / 50]×100%, take the average value of 3 parallel samples as the test result.

[0294] (2) Air permeability test of the separator membrane

[0295] For the air permeability test of the separator membrane, please refer to GB / T 36363-2018.

[0296] Cut the separator membrane into 5cm squares. Using a breathability meter, apply a pressure of 1.21kPa and test the permeability of 100ml of air, finding it to be 6.45cm. 2 The time required for the separator to breathe is taken as its air permeability value, expressed in seconds per 100 ml. The average of three parallel samples is taken as the test result. The higher the air permeability value of the separator, the worse its air permeability.

[0297] (3) Cycle performance test of secondary battery cells

[0298] At 25℃, a single secondary battery cell is charged to 3.8V with a constant current of 1 / 3C, then charged to a current of 0.05C with a constant voltage of 3.8V, left to rest for 5 minutes, and then discharged to 2.0V with a constant current of 1 / 3C. The resulting discharge capacity is recorded as the initial capacity C0. The above charging and discharging steps are repeated, and the discharge capacity Cn of the single secondary battery cell after the nth cycle is recorded. The capacity retention rate of the single secondary battery cell after each cycle is Pn = (Cn / C0) × 100%. The capacity retention rate of the single secondary battery cell after 500 cycles can be used to reflect the difference in cycle performance of the single secondary battery cell.

[0299] Table 1

[0300] The test results above show that phenolic resin organic particles that simultaneously meet the requirements of a volume distribution particle size Dv50 of 100nm-800nm ​​and a particle size distribution (Dv90-Dv10) / Dv50 of 1.4-3 can give the separator membrane both high air permeability and low thermal shrinkage, and also give the secondary battery cell good cycle performance.

[0301] It should be noted that this disclosure is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same essential structure and achieving the same effect as the technical concept within the scope of this disclosure are included in the technical scope of this disclosure. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, are also included in the scope of this disclosure without departing from the spirit of this disclosure.

Claims

1. An isolation membrane comprising a porous base membrane and a coating on at least one side of the porous base membrane, wherein, The coating comprises phenolic resin-based organic particles, the volume distribution particle size Dv50 of the phenolic resin-based organic particles is 100-800 nm, and the particle size distribution (Dv90-Dv10) / Dv50 of the phenolic resin-based organic particles is 1.4-3.

2. The separator film according to claim 1, wherein The volume distribution particle size Dv50 of the phenolic resin-based organic particles is 200-600 nm.

3. The separator film according to claim 1 or 2, wherein The particle size distribution (Dv90-Dv10) / Dv50 of the phenolic resin-based organic particles is 1.6-2.

7.

4. The separator film according to any one of claims 1-3, wherein, The volume distribution particle size Dv90 of the phenolic resin-based organic particles is 800-1800 nm; and / or, The volume distribution particle size Dv10 of the phenolic resin-based organic particles is 50-200 nm.

5. The separator film according to any one of claims 1-4, wherein, The volume distribution particle size Dv90 of the phenolic resin-based organic particles is 820-1250 nm; and / or, The volume distribution particle size Dv10 of the phenolic resin-based organic particles is 90-185 nm.

6. The separator film according to any one of claims 1 to 5, wherein The phenolic resin-based organic particles have no melting point; and / or, the phenolic resin-based organic particles have no glass transition temperature below 300℃.

7. The separator film according to any one of claims 1 to 6, wherein The phenolic resin-based organic particles are thermosetting resol.

8. The separator film according to any one of claims 1 to 7, wherein The phenolic resin-based organic particles have a true density of 1.0 g / cm 3 -1.4 g / cm 3 .

9. The separator film according to any one of claims 1-8, wherein, The mass content of the phenolic resin-based organic particles in the coating is 50-99% based on the total mass of the coating; and / or, The thickness of the coating is 0.5-5 μm; and / or, The areal density of the coating is 0.45 g / m 2 - 4.5 g / m 2 .

10. The separator film according to any one of claims 1 to 9, wherein The ratio of the volume distribution particle size Dv50 of the phenolic resin-based organic particles to the average pore size of the porous base film is greater than or equal to 1.

5.

11. The separator film according to any one of claims 1-10, wherein, The longitudinal heat shrinkage of the separator film is less than or equal to 2% when heated at 130℃ for 1 h; and / or, The transverse heat shrinkage of the separator film is less than or equal to 2% when heated at 130℃ for 1 h; and / or, The air permeability of the separator film is 160-230 s / 100 mL.

12. A phenol-formaldehyde resin-based organic particle, wherein, The volume distribution particle size Dv50 of the phenolic resin-based organic particles is 100-800 nm, and the particle size distribution (Dv90-Dv10) / Dv50 of the phenolic resin-based organic particles is 1.4-3.

13. The phenolic-resin-based organic particles according to claim 12, wherein, The volume distribution particle size Dv50 of the phenolic resin-based organic particles is 200-600 nm.

14. The phenolic-resin-based organic particles according to claim 12 or 13, wherein, The particle size distribution (Dv90-Dv10) / Dv50 of the phenolic resin-based organic particles is 1.6-2.

7.

15. The phenolic resin-based organic particles according to any one of claims 12-14, wherein, The volume distribution particle size Dv90 of the phenolic resin-based organic particles is 800-1800 nm; and / or, The volume distribution particle size Dv10 of the phenolic resin-based organic particles is 50-200 nm.

16. The phenolic resin-based organic particles according to any one of claims 12-15, wherein, The phenolic resin-based organic particles have a volume distribution particle size Dv90 of 820 nm-1250 nm; and / or, The phenolic resin-based organic particles have a volume distribution particle size Dv10 of 90 nm-185 nm.

17. The phenolic-resin-based organic particles according to any one of claims 12 to 16, wherein, The phenolic resin-based organic particles have no melting point; and / or, the phenolic resin-based organic particles have no glass transition temperature below 300℃.

18. The phenolic-resin-based organic particles according to any one of claims 12 to 17, wherein, The phenolic resin-based organic particles are thermosetting resol.

19. The phenolic-resin-based organic particles according to any one of claims 12 to 18, wherein, The phenolic resin-based organic particles have a true density of 1.0 g / cm 3 -1.4 g / cm 3 .

20. A method for preparing phenolic resin-based organic particles, comprising the following steps: providing a resol phenolic resin-based material; heating and curing the resol phenolic resin-based material to obtain a to-be-crushed resol phenolic resin-based material; crushing the to-be-crushed resol phenolic resin-based material to obtain crushed resol phenolic resin-based organic particles; mixing the crushed resol phenolic resin-based organic particles with a first dispersant and water to obtain a sanding slurry, and then performing sanding treatment and filtration treatment to obtain phenolic resin-based organic particles, the first dispersant being a high-molecular dispersant, the phenolic resin-based organic particles having a volume distribution particle size Dv50 of 100 nm-800 nm, and the phenolic resin-based organic particles having a particle size distribution (Dv90-Dv10) / Dv50 of 1.4-3.

21. The method of claim 20, wherein, the first dispersant comprises one or more of a polyether dispersant, a polyacrylic acid dispersant, a polycarboxylate dispersant, polyvinylpyrrolidone, and polyethylene glycol; and / or, the mass of the first dispersant is 0.01%-2% of the mass of the crushed resol phenolic resin-based organic particles.

22. A method for preparing phenolic resin-based organic particles, comprising the following steps: providing a foaming agent and a resol phenolic resin-based material; mixing the foaming agent and the resol phenolic resin-based material uniformly, and then heating and curing to obtain a to-be-crushed resol phenolic resin-based material; crushing the to-be-crushed resol phenolic resin-based material to obtain crushed resol phenolic resin-based organic particles; sanding the crushed resol phenolic resin-based organic particles to obtain phenolic resin-based organic particles, the phenolic resin-based organic particles having a volume distribution particle size Dv50 of 100 nm-800 nm, and the phenolic resin-based organic particles having a particle size distribution (Dv90-Dv10) / Dv50 of 1.4-3.

23. The method of claim 22, wherein, the mass of the foaming agent is 1%-20% of the mass of the resol phenolic resin-based material; and / or, the foaming agent comprises an organic foaming agent and / or an inorganic foaming agent.

24. The method of claim 22 or 23, wherein, The second dispersant is added when the crushed resol phenolic resin-based organic particles are subjected to sanding treatment.

25. The method of claim 24, wherein, the second dispersant comprises one or more of a polyether dispersant, a polyacrylic acid dispersant, a polycarboxylate dispersant, polyvinylpyrrolidone, and polyethylene glycol; and / or, the mass of the second dispersant is 0.01%-2% of the mass of the crushed resol phenolic resin-based organic particles.

26. A secondary battery cell comprising a positive electrode sheet, a negative electrode sheet, and the separator film according to any one of claims 1 to 11, the separator film being disposed between the positive electrode sheet and the negative electrode sheet.

27. A battery device comprising a plurality of the secondary battery cell according to claim 26.

28. An electrically powered device comprising the secondary battery cell according to claim 26 or the battery device according to claim 27.

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