Diaphragm and preparation method thereof, battery and electric device

Abstract

The invention discloses a diaphragm and a preparation method thereof, a battery and an electric device. The diaphragm comprises a diaphragm base material and an organic porous membrane layer. Wherein the organic porous membrane layer is arranged on at least one surface of the diaphragm base material, and the organic porous membrane layer contains through holes with the diameter of 0.5-10nm. The diaphragm can effectively improve the safety performance of a battery cell, so that the phenomenon that a large amount of active ions rapidly generate dendritic crystals on a negative electrode interface due to the defects of micropores, pinholes and the like of an existing diaphragm is effectively reduced. The battery comprises the diaphragm.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to a separator and its preparation method, a battery, and an electrical device. Background Technology

[0002] With the widespread application of batteries in fields including energy storage systems and new energy vehicles, the safety of ion batteries is receiving increasing attention.

[0003] A lithium-ion battery mainly consists of a positive electrode, a negative electrode, and a separator placed between the positive and negative electrodes. The separator isolates the positive and negative electrodes to prevent short circuits while allowing lithium ions to pass through. Therefore, the separator plays a crucial role in the safety of lithium-ion batteries.

[0004] However, due to limitations in their manufacturing processes, existing separators are prone to defects such as micropores and pinholes. During battery charging, these defects cause active ions to migrate to the negative electrode surface too quickly, preventing them from effectively embedding into the negative electrode material. This leads to crystallization and dendrite growth at the negative electrode interface, which can easily penetrate the separator and cause a short circuit between the positive and negative electrodes, thus increasing the battery's safety risks. Summary of the Invention

[0005] In view of the above problems, this application provides a separator, a method for preparing the separator, and a battery containing the separator, to solve the technical problem that defects in existing separators cause crystallization and dendrite growth at the negative electrode interface in the battery cell.

[0006] In a first aspect, embodiments of this application provide a diaphragm. The diaphragm of this application includes a diaphragm substrate and an organic porous membrane layer disposed on at least one surface of the diaphragm substrate. The organic porous membrane layer contains through-pores with a diameter of 0.5–10 nm.

[0007] The separator of this application embodiment adds an organic porous membrane layer to the surface of the separator substrate and restricts the pore size of the organic porous membrane layer. This organic porous membrane layer can improve defects such as micropores and pinholes in the separator substrate and also has a synergistic effect with the separator substrate in regulating the flux of active ions. When the separator of this application embodiment is used in the separator of a battery cell, the active ion flux of the separator of this application embodiment can be adapted to the active ion insertion rate of the negative electrode material, which can alleviate the phenomenon of large-scale accumulation of active ions on the negative electrode surface, thereby effectively mitigating the adverse phenomena such as crystallization and further dendrite growth at the negative electrode interface. Moreover, the diameter range of the through-pores contained in the organic porous membrane layer is close to the critical nucleus size of the dendrites. This organic porous membrane layer can also alleviate the growth of dendrites towards the positive electrode, thereby reducing the probability of puncturing the separator of this application embodiment. Therefore, the separator of this application embodiment can effectively improve the safety performance of the battery cell, thereby effectively reducing the phenomenon of large-scale and rapid dendrite formation of active ions at the negative electrode interface caused by defects such as micropores and pinholes in existing separators.

[0008] In some embodiments, the diameter of the through-holes is 0.5–3 nm. This range of through-hole diameters can further enhance the role of the organic porous membrane layer as a pore-regulating functional layer in the separator of this application embodiment, improve its synergistic effect with the separator substrate in regulating the flux of active ions, and further improve the compatibility between the active ion flux of the separator in the battery cell and the active ion insertion rate of the negative electrode material, thereby further improving the safety of the battery cell.

[0009] In some embodiments, the thickness of the organic porous membrane is 5–30 nm.

[0010] In some embodiments, the thickness of the organic porous membrane is 8–20 nm.

[0011] Organic porous membrane layers within this thickness range can enhance the pore-regulating function of the membrane layer, improve its synergistic effect with the membrane substrate in regulating the flux of active ions, and further alleviate adverse phenomena such as crystallization and dendrite formation at the negative electrode interface of the battery cell. Simultaneously, it improves the mechanical properties of the membrane.

[0012] In some embodiments, the porosity of the organic porous membrane is 0.5% to 80%.

[0013] In some embodiments, the porosity of the organic porous membrane layer is 10% to 50%.

[0014] The porosity within this range, together with the membrane substrate, can adjust the total porosity of the membrane in the embodiments of this application, thereby further adjusting the active ion flux of the membrane, further improving the compatibility between the membrane and the active ion insertion rate of the negative electrode material, and thus improving the safety performance of the battery cell.

[0015] In some embodiments, the organic porous membrane layer is a three-dimensional fibrous membrane layer comprising organic fibers.

[0016] In the embodiments, the aspect ratio of a single organic fiber is (2-5000):1.

[0017] In the embodiments, the diameter of a single organic fiber is 2 to 100 nm.

[0018] In the embodiments, the length of a single organic fiber is 50 nm to 10 μm.

[0019] A three-dimensional fiber membrane layer composed of organic fibers is used as an organic porous membrane layer. The length and diameter of the organic fibers are further controlled within the above-mentioned range, so that the organic porous membrane layer has a rich three-dimensional pore structure, which increases the pore content and enhances the synergistic effect of regulating the active ion flux between the membrane and the membrane substrate. This further regulates the active ion flux of the membrane in the embodiments of this application, and improves the rate performance of the battery cell by alleviating the adverse phenomena such as crystallization and dendrite formation at the negative electrode interface of the battery cell.

[0020] In this embodiment, chemical bonds are formed at the contact portions of adjacent organic fibers in the three-dimensional fiber membrane. The formation of chemical bonds at the contact portions of adjacent organic fibers effectively enhances the stability of the three-dimensional porous structure contained in the three-dimensional fiber membrane, thereby improving the stability of the synergistic effect of regulating active ion flux between the three-dimensional fiber membrane and the membrane substrate, and simultaneously improving the mechanical properties of the membrane.

[0021] In some embodiments, the organic material of the organic porous membrane layer contains at least one polar group selected from nitrogen-containing groups and oxygen-containing groups. These types of polar groups can effectively improve the active ion conductivity of the organic porous membrane layer, thereby effectively improving the active ion migration rate and flux of the membrane in this embodiment, and improving the compatibility between the active ion flux of the membrane and the active ion insertion rate of the negative electrode material contained in the negative electrode.

[0022] In some embodiments, the organic material of the organic porous membrane layer includes at least one of polyamide, polycarbonate, polyphenylene ester, polyurea, and poly(m-phenylene isophthalamide).

[0023] These organic materials can form a three-dimensional fibrous membrane structure on the surface of the separator substrate through in-situ polymerization, and adjust the pore diameter and porosity of the organic porous membrane to improve its performance. They are also rich in polar groups, which can effectively improve the active ion conductivity of the organic porous membrane, enhance the compatibility between the active ion flux of the separator in this embodiment and the active ion insertion rate of the negative electrode material, and further alleviate the formation and growth of dendrites at the negative electrode interface in the battery cell.

[0024] In some embodiments, the organic porous membrane layer contains inorganic fibers, and the inorganic fibers account for 0.05% to 3.84% of the organic porous membrane layer by mass.

[0025] In the embodiments, the inorganic fiber has a mass percentage content of 0.6% to 2.0% in the organic porous membrane layer.

[0026] Adding this inorganic fiber to the organic porous membrane can effectively participate in regulating the pore structure of the organic porous membrane, especially the diameter of the through pores, and improve the synergistic effect of regulating the flux of active ions between the organic porous membrane and the membrane substrate; at the same time, it can also act as a reinforcing rib or form molecular forces or chemical bonds with organic matter, thereby enhancing the mechanical properties of the organic porous membrane, such as tensile strength and the stability of mechanical properties.

[0027] In the embodiments, the aspect ratio of the inorganic fibers is (10-1000):1; and / or

[0028] In the embodiments, the length of the inorganic fiber is 0.1–5 μm; and / or

[0029] In the embodiments, the diameter of the inorganic fiber is 5–100 nm; and / or

[0030] In the embodiments, the inorganic fibers include at least one of silicon dioxide, titanium dioxide, aluminum oxide, silicon carbide, and boron carbide.

[0031] By controlling the aspect ratio, diameter, length, and material type of inorganic fibers within the aforementioned ranges, the role of inorganic fibers in regulating the pore structure, especially the diameter of the pores, can be further enhanced, as can the synergistic effect of the organic porous membrane on regulating the flux of active ions between the organic porous membrane and the membrane substrate; and the mechanical properties of the organic porous membrane can also be improved.

[0032] In some embodiments, the thickness of the separator is 5–50 μm. This thickness range allows for further adjustment of the active ion flux of the separator, further improving its compatibility with the active ion insertion rate of the negative electrode material, thereby enhancing the safety performance of the battery cell.

[0033] In some embodiments, the porosity of the separator is 20% to 60%. This range of porosity can further adjust the active ion flux of the separator, further improving the compatibility with the active ion insertion rate of the negative electrode material, thereby improving the safety performance of the battery cell.

[0034] Secondly, embodiments of this application provide a method for preparing a diaphragm. The method for preparing a diaphragm according to embodiments of this application includes the following steps:

[0035] An organic porous membrane layer is formed on at least one surface of a membrane substrate to obtain a membrane;

[0036] The organic porous membrane layer formed contains through pores with a diameter of 0.5 to 10 nm.

[0037] The membrane preparation method of this application directly forms an organic porous membrane layer with a specific pore diameter range on at least one surface of the membrane substrate. This organic porous membrane layer and the membrane substrate can play a synergistic role in regulating the flux of active ions, so that the flux of active ions in the prepared membrane is adapted to the active ion insertion rate of the negative electrode material contained in the negative electrode. This can significantly alleviate the adverse phenomena such as crystallization and further dendrite formation at the negative electrode interface in the battery cell, thereby improving the safety performance of the battery cell.

[0038] In some embodiments, the method of forming an organic porous membrane layer on at least one surface of the diaphragm substrate includes the following steps:

[0039] A first wet film layer is formed on at least one surface of the diaphragm substrate by a first polymer monomer solution;

[0040] An inorganic polymerization inhibitor is disposed on the surface of the first wet film layer opposite to the diaphragm substrate;

[0041] A second wet film layer is formed on the surface of the first wet film layer where the inorganic polymerization inhibitor is disposed, by the second polymer monomer solution.

[0042] The composite wet membrane formed by the first wet membrane layer and the second wet membrane layer is subjected to an interfacial polymerization reaction to generate the organic porous membrane layer.

[0043] The inorganic polymerization inhibitor is fibrous.

[0044] By separately forming polymer monomers into films and then performing interfacial polymerization reactions, an interfacial polymer film is formed in situ on the surface of the diaphragm substrate. This effectively improves the regulation of the mechanical energy of the pore structure contained in the organic porous membrane layer, thereby enhancing the synergistic effect of regulating the active ion flux between the organic porous membrane layer and the diaphragm substrate.

[0045] In the embodiment, the mass ratio of the first polymer monomer in the first wet film layer, the second polymer monomer in the second wet film layer, and the inorganic polymerization inhibitor disposed between the first wet film layer and the second wet film layer is 1:(0.3~0.9):(0.001~0.05).

[0046] In the embodiments, the mass percentage of the first polymer monomer in the first polymer monomer solution is 10% to 30%.

[0047] In the embodiments, the mass percentage of the second polymer monomer in the second polymer monomer solution is 5% to 35%.

[0048] In this embodiment, the temperature of the interfacial polymerization reaction is 40°C to 70°C.

[0049] By controlling the interfacial polymerization film-forming conditions within the above range, the interfacial polymerization reaction rate can be adjusted to generate fibrous polymers to form a three-dimensional fibrous membrane layer. This also adjusts the uniformity of the porosity and pore size of the organic porous membrane layer, improving the membrane quality. Consequently, the synergistic effect of the organic porous membrane layer and the membrane substrate in regulating the flux of active ions is further enhanced, and the mechanical properties of the membrane are improved.

[0050] In the embodiments, the first polymer monomer includes at least one of pyromellitic methyl chloride, diphenyl carbonate, terephthalic acid, toluene diisocyanate, and isophthaloyl chloride.

[0051] In the embodiments, the second polymer monomer includes at least one of methylpropanediol, bisphenol A, ethylene glycol, ethylenediamine, and m-phenylenediamine.

[0052] These types of first and second polymer monomers undergo interfacial polymerization to generate fibrous polymers and form three-dimensional fibrous membranes, improving the three-dimensional pore structure of the three-dimensional fibrous membranes. They are also rich in polar groups, which can effectively improve the active ion conductivity of the organic porous membranes and improve the active ion flux of the membrane in the embodiments of this application to match the active ion insertion rate of the negative electrode material.

[0053] In the embodiments, the aspect ratio of the inorganic polymerization inhibitor is (10-1000):1.

[0054] In the embodiments, the length of the inorganic polymerization inhibitor is 0.1–5 μm.

[0055] In the embodiments, the diameter of the inorganic polymerization inhibitor is 5-100 nm.

[0056] In the embodiments, the inorganic polymerization inhibitor includes at least one of silicon dioxide, titanium dioxide, aluminum oxide, silicon carbide, and boron carbide.

[0057] By controlling the aspect ratio, diameter, length, and type of inorganic polymerization inhibitors within the aforementioned ranges, the roles of polymerization inhibitors and interfacial polymerization reaction templates can be further enhanced, the interfacial polymerization reaction rate can be adjusted, the pore structure of the generated organic porous membrane can be adjusted and improved, and the synergistic effect of the organic porous membrane and the membrane substrate in regulating the flux of active ions and the mechanical properties of the membrane can be further improved.

[0058] Thirdly, embodiments of this application provide a battery. The battery of this application embodiment includes a separator according to embodiments of this application or a separator prepared by the separator preparation method of embodiments of this application.

[0059] In the embodiments of this application, the amount of active ions migrating to the negative electrode per unit time is matched with the active ion insertion rate of the negative electrode material, which significantly alleviates adverse phenomena such as crystallization and further dendrite formation at the negative electrode interface, thereby significantly improving the safety of the battery.

[0060] Fourthly, embodiments of this application provide an electrical device. The electrical device in this application includes the battery described in this application.

[0061] The electrical devices described in this application have high safety and long service life.

[0062] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0063] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0064] Figure 1 This is a schematic diagram of the structure of a diaphragm according to an embodiment of this application;

[0065] Figure 2 This is a schematic diagram of another structure of the diaphragm according to an embodiment of this application;

[0066] Figure 3 This is a schematic diagram of the structure of a single battery cell according to an embodiment of this application;

[0067] Figure 4 for Figure 3 The diagram shows an exploded view of a single battery cell.

[0068] Figure 5 This is a schematic diagram of one embodiment of the battery module of this application;

[0069] Figure 6 This is an exploded view of the battery pack according to an embodiment of this application;

[0070] Figure 7 This is a schematic diagram of one embodiment of an electrical device that uses a battery as a power source, as described in the present application.

[0071] Figure 8The images shown are SEM images of the organic porous membrane layer and the membrane substrate of the diaphragm provided in Example A8; wherein, image a is an SEM image of the organic porous membrane layer contained in the diaphragm, and image b is an SEM image of the membrane substrate contained in the diaphragm.

[0072] The reference numerals in the detailed embodiments are as follows:

[0073] 10-Separator, 11-Separator substrate, 12-Organic porous membrane layer;

[0074] 20-Battery cell, 21-Casing, 22-Electrode assembly, 23-Cover plate;

[0075] 30-Battery Module;

[0076] 40 - Battery pack, 41 - Upper casing, 42 - Lower casing. Detailed Implementation

[0077] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0078] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0079] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0080] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0081] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0082] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0083] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0084] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0085] Lithium-ion batteries, in particular, are important energy storage devices widely used in electric vehicles, smartphones, tablets, and other fields. The performance and safety of lithium-ion batteries are crucial for the normal operation of these devices and the safety of users. With technological advancements and societal progress, people are placing higher demands on battery safety.

[0086] A lithium-ion battery consists of a positive electrode, a negative electrode, and a separator placed between them. The separator, as a crucial component of the lithium-ion battery, functions to isolate the positive and negative electrodes, prevent short circuits, and allow lithium ions to pass through. Therefore, the separator plays a vital role in the safety of lithium-ion batteries.

[0087] Currently, polyolefin materials are widely used as membrane materials in lithium-ion batteries. However, existing polyolefin membranes have some shortcomings in their preparation and use. For example, due to limitations in the manufacturing process, micropores and pinholes are easily formed on the surface and inside of existing polyolefin membranes. These defects can cause active ions to migrate to the anode surface too quickly during the cell charging process, leading to a series of problems.

[0088] Specifically, the increased migration rate of active ions prevents them from effectively embedding into the negative electrode material. For example, the inability to effectively embed into the interlayer of graphite negative electrode material leads to crystallization and dendrite growth at the negative electrode interface. These dendrites, such as lithium dendrites, are dendritic structures that may continue to grow along the defect pores of the separator, eventually causing a short circuit between the positive and negative electrodes inside the cell. This short circuit not only leads to battery self-discharge, reducing battery capacity and lifespan, but more seriously, it can trigger battery thermal runaway, fire, or even explosion, posing a serious threat to the life and property safety of users.

[0089] To address these issues, researchers have been exploring methods to improve membrane performance. For example, one publicly available approach involves applying a coating of inorganic materials to the membrane surface. However, this coating often fails to effectively repair defects such as micropores and pinholes in the membrane, and may even lead to other problems, such as reduced overall permeability and wettability, thus negatively impacting the overall migration efficiency of active ions.

[0090] Therefore, in order to effectively improve the dendrite phenomenon at the negative electrode caused by defects such as micropores and pinholes in existing separators and improve the safety of the battery cell, research has found that when an organic porous film layer is set on the surface of the separator substrate and the diameter of the organic porous film layer is controlled, it can improve the defects such as micropores and pinholes in the separator substrate and also play a regulatory role in the migration of active ions with the separator substrate. This can significantly alleviate the dendrite phenomenon at the negative electrode interface and improve the safety performance of the battery cell.

[0091] Diaphragm:

[0092] In a first aspect, embodiments of this application provide a diaphragm. The diaphragm of this application includes a diaphragm substrate and an organic porous membrane layer. The organic porous membrane layer is disposed on at least one surface of the diaphragm substrate, wherein the organic porous membrane layer contains through-pores with a diameter of 0.5–10 nm.

[0093] In the separator of this application embodiment, the separator substrate serves as the base layer supporting the organic porous membrane layer, while also functioning as a conventional separator in the battery cell. The surfaces of the separator refer to the two surfaces of the separator that are opposite each other. In this case, the organic porous membrane layer can be disposed on one of the separator surfaces, or simultaneously on both opposite surfaces, forming a composite separator structure with two or more layers on the separator substrate. An organic porous membrane layer refers to a membrane layer made of organic material and possessing a porous structure. The through-pores contained in the organic porous membrane layer represent the pore structure extending from one surface of the organic porous membrane layer to the opposite surface. These through-pores can be linear, curved, or multiple interconnected pores forming a three-dimensional porous structure.

[0094] The separator of this application embodiment adds an organic porous membrane layer containing through holes to at least one surface of the separator substrate, and controls the diameter of the through holes to be in the range of 0.5-10 nm. This organic porous membrane layer acts as a porosity regulating layer on the surface of the separator substrate, effectively improving defects such as micropores and pinholes in the separator substrate. Furthermore, it enhances the regulation of active ion flux with the separator substrate. Thus, when the separator of this application embodiment is used in a battery cell, the active ion flux of the separator can be matched with the active ion insertion rate of the negative electrode material, effectively mitigating the excessive accumulation of active ions on the negative electrode surface within a certain time. This significantly alleviates undesirable phenomena such as crystallization and further dendrite growth at the negative electrode interface. Moreover, the diameter range of the through holes in the organic porous membrane layer is close to the critical nucleus size of dendrites. Therefore, the organic porous membrane layer can also mitigate dendrite growth towards the positive electrode, reducing the probability of puncturing the separator of this application embodiment. Therefore, the separator of the present application embodiment can effectively improve the safety performance of the battery cell, thereby effectively reducing the phenomenon of large-scale and rapid dendrite formation of active ions at the negative electrode interface caused by defects such as micropores and pinholes in existing separators.

[0095] Based on the relationship between the membrane substrate and the organic porous membrane layer in the diaphragm of the embodiments of this application described above, in some embodiments, the diaphragm of the embodiments of this application may be as follows: Figure 1 or Figure 2 The structure shown:

[0096] In some embodiments, the structure of the diaphragm in this application can be as follows: Figure 1 As shown, the diaphragm 10 in this embodiment includes a diaphragm substrate 11, which has two surfaces disposed opposite to each other, and an organic porous membrane layer 12 is disposed on one of the surfaces of the diaphragm substrate 11.

[0097] In some embodiments, the structure of the diaphragm in this application can be as follows: Figure 2As shown, the diaphragm 10 in this embodiment includes a diaphragm substrate 11, which has two surfaces disposed opposite to each other, and an organic porous membrane layer 12 is disposed on each of the two surfaces disposed opposite to each other.

[0098] Regardless of the structure of the diaphragm in the embodiments of this application, the organic porous membrane layer 12 contained therein can play the role of a pore regulation functional layer, effectively improve the pore defects present in the diaphragm substrate 11, and have a synergistic effect with the diaphragm substrate 11 in regulating the flux of active ions, thereby improving the compatibility between the active ion flux of the diaphragm in the embodiments of this application and the active ion insertion rate of the negative electrode material, thereby alleviating adverse phenomena such as crystallization and further dendrite formation at the negative electrode interface, and improving the safety of the battery cell.

[0099] In some embodiments, the thickness of the diaphragm in this application can be 5–50 μm, and optionally 7 μm.

[0100] ~20μm. In the examples, the thickness can be typical but not limiting, such as 5μm, 7μm, 8μm, 9μm, 10μm, 13μm, 15μm, 18μm, 20μm, 30μm, 40μm, 50μm, or any range between two thickness values. Here, the thickness of the separator refers to the sum of the thickness of the separator substrate and the thickness of the organic porous membrane layer, such as... Figure 1 The sum of the thickness 'a' of the diaphragm substrate 11 and the thickness 'b' of the organic porous membrane layer 12 (i.e., a + b), or as... Figure 2 The thickness 'a' of the membrane substrate 11 is the sum of the thicknesses 'b' of the two organic porous membrane layers 12 (i.e., a + 2b). This thickness range allows for further adjustment of the membrane's active ion flux, further improving its compatibility with the active ion insertion rate of the negative electrode material, thereby mitigating undesirable phenomena such as crystallization and dendrite formation at the negative electrode interface. The membrane thickness can be measured using a micrometer or a thickness gauge, or, of course, precisely measured using a scanning electron microscope.

[0101] In some embodiments, the porosity of the membrane in this application can be 20% to 60%, optionally 30% to 50%. In exemplary cases, it can be typical but not limiting porosities such as 20%, 35%, 37%, 40%, 42%, 44%, 46%, 48%, 50%, 55%, and 60%, or any range between two porosity values. The porosity of the membrane refers to the porosity of the composite membrane layer formed by the membrane substrate and the organic porous membrane layer. This range of porosity can further adjust the active ion flux of the membrane, further improve the compatibility with the active ion insertion rate of the negative electrode material, thereby mitigating undesirable phenomena such as crystallization and dendrite formation at the negative electrode interface. The porosity of the membrane can be measured using conventional nitrogen adsorption or conventional mercury intrusion porosimetry.

[0102] [Separator Substrate]

[0103] In the diaphragm of the present application embodiment, the diaphragm substrate it contains constitutes the diaphragm matrix, performs the function of a conventional diaphragm, and at the same time acts as a carrier for loading the organic porous membrane layer.

[0104] In some embodiments, the thickness of the diaphragm substrate is as follows: Figure 1 and Figure 2 The thickness 'a' of the separator substrate 11 can be 4–48 μm, optionally 5–17 μm. In the exemplary example, it can be a typical but non-limiting thickness such as 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 10 μm, 14 μm, 15 μm, 16 μm, 17 μm, 20 μm, 25 μm, 35 μm, 40 μm, 48 μm, or any range between two thickness values. The separator substrate within this thickness range can interact with the organic porous membrane layer, further regulating the active ion flux of the separator in this embodiment, thereby mitigating adverse phenomena such as crystallization and dendrite formation at the negative electrode interface. Simultaneously, it can also adjust the total thickness and mechanical properties of the separator in this embodiment, thereby improving the cell's related electrochemical performance, including energy density. The thickness of the separator substrate can be measured using a micrometer or a thickness gauge, or, of course, precisely measured using a scanning electron microscope.

[0105] In some embodiments, the membrane substrate may comprise a single-layer or multi-layer membrane formed of at least one material selected from polyolefins, polyvinylidene fluoride (PVDF), polyimide, glass fiber, nonwoven fabric, spandex, aramid, etc. In an exemplary embodiment, the polyolefin may comprise at least one material selected from polyethylene (PE), polypropylene (PP), etc. Membrane substrates made of these materials can enhance the synergistic effect of regulating the active ion flux with the organic porous membrane layer, improving the compatibility between the active ion flux of the membrane in this embodiment and the active ion insertion rate of the negative electrode material. Furthermore, it also possesses high thermal stability, chemical stability, corrosion resistance, and good mechanical strength, thereby improving the thermal stability, chemical stability, corrosion resistance, and good mechanical strength of the membrane in this embodiment.

[0106] [Organic porous membrane layer]

[0107] In some embodiments, the diameter of the pores in the organic porous membrane layer described above is in the range of 0.5–10 nm, and can be further ranged from 0.5–3 nm. In exemplary examples, typical but non-limiting diameters such as 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, and 10 nm, or any range between two diameter values, can be used. Here, the diameter of the pore refers to the pore size. This range of pore sizes can further enhance the role of the organic porous membrane layer as a porosity regulating layer in the separator of this application embodiment, improve its synergistic effect with the separator substrate in regulating the flux of active ions, further improve the compatibility between the active ion flux of the separator in the battery cell and the active ion insertion rate of the negative electrode material, further alleviate adverse phenomena such as crystallization and dendrite formation at the negative electrode interface of the battery cell, and further improve the safety of the battery cell. The diameter of the pores in the organic porous membrane layer can be accurately measured using scanning electron microscopy (SEM) or transmission electron microscopy (TEM).

[0108] In some embodiments, the organic porous membrane layer, such as Figure 1 The thickness b of the organic porous membrane layer 12 can be 5–30 nm, optionally 8–20 nm. In the example, it can be a typical but non-limiting thickness such as 5 nm, 8 nm, 10 nm, 12 nm, 15 nm, 18 nm, 20 nm, 22 nm, 25 nm, 28 nm, 30 nm, or any range between two thickness values. The thickness of this organic porous membrane layer refers to the thickness of the organic porous membrane layer disposed on one surface of the separator substrate. Organic porous membrane layers within this thickness range can enhance the pore-regulating functional layer effect, improve its synergistic effect with the separator substrate in regulating the flux of active ions, further alleviate adverse phenomena such as crystallization and dendrite formation at the negative electrode interface of the battery cell, and thus further improve the safety of the battery cell. Simultaneously, it improves the mechanical properties of the separator together with the separator substrate. The thickness of this organic porous membrane layer can be measured using a thickness gauge, or it can be precisely measured using electron microscopy, such as scanning electron microscopy and X-ray photoelectron spectroscopy (XPS).

[0109] In some embodiments, the organic porous membrane layer, such as Figure 1The porosity of the organic porous membrane layer 12 is 0.5% to 80%, optionally 10% to 50%. In the exemplary example, it can be a typical but non-limiting porosity such as 0.5%, 1%, 5%, 10%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, or any range between two porosity values. The porosity of this organic porous membrane layer refers to the porosity of the organic porous membrane layer disposed on one surface of the separator substrate. This range of porosity, together with the separator substrate, can adjust the total porosity of the separator in this embodiment. If the total porosity of the separator in this embodiment is adjusted to the range mentioned above, the active ion flux of the separator can be further adjusted, further improving the compatibility between the separator and the active ion insertion rate of the negative electrode material, thereby improving the safety performance of the battery cell. The porosity of the organic porous membrane layer can be measured by conventional nitrogen adsorption or conventional mercury intrusion porosimetry after the membrane substrate contained in the membrane of the embodiment of this application is peeled off.

[0110] In some embodiments, the organic porous membrane layer is a three-dimensional fiber membrane layer comprising organic fibers. Using a three-dimensional fiber membrane layer composed of organic fibers as the organic porous membrane layer results in a rich three-dimensional pore structure, further increasing the pore content within the organic porous membrane layer and enhancing its synergistic effect with the membrane substrate in regulating the active ion flux. This further regulates the active ion flux of the membrane in the embodiments of this application, mitigating adverse phenomena such as crystallization and dendrite formation at the negative electrode interface of the battery cell. When the organic porous membrane layer is a three-dimensional fiber membrane layer, the diameter of the pores, including the through-holes, in the organic porous membrane layer is equal to the distance between two adjacent fibers.

[0111] In the embodiments, when the organic porous membrane layer mentioned above is a three-dimensional fiber membrane layer, the aspect ratio of a single organic fiber in the three-dimensional fiber membrane layer is (2-5000):1, which can be selected as (10-1000):1. In the exemplary examples, it can be a typical but non-limiting aspect ratio such as 2:1, 10:1, 30:1, 50:1, 80:1, 100:1, 300:1, 500:1, 1000:1, 2000:1, 3000:1, 4000:1, 5000:1, etc., or any range between two aspect ratios. This range of aspect ratios can effectively increase the three-dimensional porosity content in the three-dimensional fiber membrane layer and effectively control the diameter of the pores, including the through holes, of the three-dimensional fiber membrane layer, thereby improving the effect of the three-dimensional fiber membrane layer and the membrane substrate in regulating the active ion flux of the membrane in the embodiments of this application.

[0112] In the embodiments, when the organic porous membrane layer mentioned above is a three-dimensional fiber membrane layer, the diameter of a single organic fiber in the three-dimensional fiber membrane layer can be 2-100 nm, optionally 10-80 nm. In the exemplary examples, it can be a typical but non-limiting diameter such as 2 nm, 4 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, or any range between two diameter values. Organic fibers within this diameter range can increase the three-dimensional porosity content in the three-dimensional fiber membrane layer and effectively control the diameter of pores, including through-holes. For example, controlling the diameter of through-holes within the range mentioned above can further alleviate undesirable phenomena such as crystallization and dendrite formation at the negative electrode interface of the battery cell. The diameter of a single organic fiber can be accurately measured using scanning electron microscopy (SEM) or transmission electron microscopy (TEM).

[0113] In the embodiments, when the organic porous membrane layer is a three-dimensional fiber membrane layer, the length of a single organic fiber in the three-dimensional fiber membrane layer is 50 nm to 10 μm, optionally 100 to 800 nm. In the exemplary examples, typical but non-limiting lengths such as 50 nm, 60 nm, 80 nm, 100 nm, 200 nm, 400 nm, 600 nm, 800 nm, 1 μm, 3 μm, 5 μm, 8 μm, and 10 μm, or any range between two length values, can be used. Organic fibers within this length range can increase the three-dimensional porosity content in the three-dimensional fiber membrane layer and adjust the pore diameter, including the through-hole diameter, within the aforementioned range to further regulate the active ion flux with the membrane substrate. Furthermore, it can improve the mechanical properties of the three-dimensional fiber membrane layer, such as tensile strength. The length of a single organic fiber can also be precisely measured using scanning electron microscopy (SEM) or transmission electron microscopy (TEM).

[0114] In the embodiments, when the aforementioned organic porous membrane is a three-dimensional fiber membrane, chemical bonds are formed at the contact portions of adjacent organic fibers in the three-dimensional fiber membrane. In the example, these chemical bonds can be formed by cross-linking or polymerization reactions, and may include at least one of the following: covalent bonds, ionic bonds, coordination bonds, and hydrogen bonds. The formation of chemical bonds at the contact portions of adjacent organic fibers effectively enhances the stability of the three-dimensional porous structure contained in the three-dimensional fiber membrane, thereby improving the stability of the enhanced effect of regulating active ion flux between the three-dimensional fiber membrane and the membrane substrate, further improving the safety performance of the battery cell. Simultaneously, it can further improve the mechanical properties of the three-dimensional fiber membrane, such as tensile strength, and enhance the stability of its mechanical properties.

[0115] In some embodiments, the organic material of the organic porous membrane layer described above contains at least one polar group selected from nitrogen-containing groups and oxygen-containing groups. In exemplary cases, the nitrogen-containing group may include amide groups (-CO-NH-), urea groups (-NH-CO-NH-), etc., and the oxygen-containing group may include ester groups (-COO-, -O-COO-), ether groups (-O-), etc. Organic materials containing these types of polar groups, together with the pore diameter of the organic porous membrane layer, can improve the compatibility between the active ion flux of the membrane in the embodiments of this application and the active ion insertion rate of the negative electrode material, thereby alleviating undesirable phenomena such as crystallization and further dendrite formation at the negative electrode interface. The polar groups contained in the organic material can be detected and analyzed by methods such as mass spectrometry.

[0116] In the embodiments, the organic materials contained in the above-mentioned organic porous membrane layer may include condensation polymers, which may include at least one of polyamide (PA), polycarbonate (PC), polyphenylene ester, polyurea, poly(m-phenylene isophthalamide) (PMIA), and polyester. These condensation polymers can effectively form the above-mentioned organic porous membrane layer, such as by forming the above-mentioned organic porous membrane layer on the surface of the separator substrate through interfacial polymerization, such as forming a three-dimensional fiber membrane structure, and adjusting the pore diameter and porosity of the organic porous membrane layer. Simultaneously, it is rich in polar groups, which can effectively improve the active ion conductivity of the organic porous membrane layer, improve the compatibility between the active ion flux of the separator in this embodiment and the active ion insertion rate of the negative electrode material, further alleviate the formation and growth of dendrites at the negative electrode interface in the battery cell, further improve the safety performance of the battery cell, or further improve the rate capability and other electrochemical performance of the battery cell.

[0117] Based on the embodiments described above, as some embodiments of this application, the organic porous membrane layer further contains inorganic fibers. In the embodiments, the mass percentage content of the inorganic fibers in the organic porous membrane layer can be 0.05% to 3.84%, optionally 0.6% to 2.0%. In exemplary examples, it can be typical but non-limiting contents such as 0.05%, 0.6%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, and 3.84%, or a range between any two contents. Here, the mass percentage content refers to the total mass percentage content of the inorganic fibers per unit mass of the organic porous membrane layer. Adding this inorganic fiber to the organic porous membrane layer can, on the one hand, effectively participate in regulating the pore structure of the organic porous membrane layer, especially the diameter of the through pores, and improve the synergistic effect of regulating the active ion flux between the organic porous membrane layer and the membrane substrate. This further improves the compatibility between the active ion flux of the membrane in this embodiment and the active ion insertion rate of the negative electrode material, and further alleviates adverse phenomena such as crystallization and dendrite formation at the negative electrode interface. On the other hand, the inorganic fiber can also act as a reinforcing rib or form molecular forces or chemical bonds with organic matter, thereby enhancing the mechanical properties and stability of the organic porous membrane layer, including tensile strength.

[0118] In the embodiments, when the organic porous membrane layer mentioned above contains inorganic fibers, the aspect ratio of the inorganic fibers is (10 to 1000):1. In the exemplary examples, it can be a typical but non-limiting aspect ratio such as 10:1, 50:1, 100:1, 300:1, 500:1, 800:1, 1000:1, or any range between two aspect ratios.

[0119] In the embodiments, the length of the inorganic fiber can be 0.1 to 5 μm, optionally 0.5 to 3 μm. In the exemplary examples, it can be a typical but non-limiting length such as 0.1 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or any range between two length values.

[0120] In the embodiments, the diameter of the inorganic fiber is 5 to 100 nm, and can be selected as 10 to 80 nm. In the exemplary examples, it can be a typical but non-limiting length such as 5 nm, 8 nm, 12 nm, 16 nm, 20 nm, 30 nm, 50 nm, 80 nm, 100 nm, or any range between two diameter values.

[0121] By controlling the aspect ratio, diameter, and length of inorganic fibers within the aforementioned ranges, the role of inorganic fibers in regulating the pore structure, especially the diameter of the pores, of the organic porous membrane can be further enhanced, as can the synergistic effect of the organic porous membrane and the membrane substrate in regulating the flux of active ions. At the same time, the mechanical properties of the organic porous membrane can be improved.

[0122] In the example, the inorganic fiber may include at least one of silicon dioxide, titanium dioxide, alumina, silicon carbide, and boron carbide. These types of inorganic fibers have stable chemical properties and good mechanical properties. They can effectively participate in regulating the pore structure of organic porous membranes, especially the diameter of the pores, and thus help improve the stability and mechanical properties of the interface between the organic porous membrane and the electrolyte.

[0123] Diaphragm preparation method:

[0124] Secondly, embodiments of this application provide a method for preparing the diaphragm according to the embodiments of the above application.

[0125] In some embodiments, the membrane preparation method of this application includes the following steps:

[0126] S10: An organic porous membrane layer is formed on at least one surface of the diaphragm substrate.

[0127] In the preparation method of the diaphragm in this application embodiment, the diaphragm substrate in step S10 can be the diaphragm substrate contained in the diaphragm of the above application embodiment, and the formed organic porous membrane layer is also the organic porous membrane layer contained in the diaphragm of the above application embodiment. Therefore, the formed organic porous membrane layer contains through pores with a diameter of 0.5 to 10 nm.

[0128] Thus, the membrane preparation method of this application directly forms an organic porous membrane layer with a specific pore diameter range on at least one surface of the membrane substrate. This organic porous membrane layer can effectively improve the pore defects in the membrane substrate and can also play a synergistic role in regulating the flux of active ions with the membrane substrate. This makes the active ion flux of the prepared membrane compatible with the active ion insertion rate of the negative electrode material contained in the negative electrode, thereby significantly alleviating the adverse phenomena such as crystallization and further dendrite formation at the negative electrode interface in the battery cell, thereby improving the safety performance of the battery cell.

[0129] In some embodiments, the method for forming an organic porous membrane layer on the surface of a diaphragm substrate may include interfacial polymerization. In embodiments, the method for forming an organic porous membrane layer on the surface of a diaphragm substrate using interfacial polymerization may include the following steps:

[0130] S11: Form a first wet film layer on at least one surface of the diaphragm substrate by applying a first polymer monomer solution;

[0131] S12: An inorganic polymerization inhibitor is disposed on the surface of the first wet film layer away from the membrane substrate;

[0132] S13: The second polymer monomer solution is used to form a second wet film layer on the surface of the first wet film layer where the inorganic polymerization inhibitor is disposed;

[0133] S14: The composite wet membrane formed by the first wet membrane layer and the second wet membrane layer is subjected to an interfacial polymerization reaction to generate an organic porous membrane layer.

[0134] By separately forming polymer monomers into films and then performing interfacial polymerization reactions, an interfacial polymer film is formed in situ on the surface of the diaphragm substrate. This effectively improves the regulation of the mechanical energy of the pore structure contained in the organic porous membrane layer, thereby enhancing the synergistic effect of regulating the active ion flux between the organic porous membrane layer and the diaphragm substrate.

[0135] In step S11, the first polymer monomer in the first polymer monomer solution should be a monomer of a polymer, specifically an organic compound used to form the organic porous membrane layer. The concentration of the first polymer monomer in the solution should be conducive to the formation of a wet film on the surface of the membrane substrate. For example, in the embodiments, the mass percentage of the first polymer monomer in the first polymer monomer solution can be 10% to 30%. In exemplary examples, it can be a typical but non-limiting mass percentage such as 10%, 15%, 20%, 25%, or 30%, or a range between any two mass percentage values. This range of mass percentages can improve the quality of the first wet film layer formed on the surface of the membrane substrate, such as improving the uniformity and other membrane properties of the first wet film layer.

[0136] In the embodiments, the amount of the first wet film layer formed on the surface of the diaphragm substrate can make the thickness of the organic porous film layer generated in step S14 reach the thickness range of the organic porous film layer contained in the diaphragm of the above-described embodiments, such as making the thickness of the organic porous film layer formed 5 to 30 nm.

[0137] In the embodiments, the method for forming a first wet film layer on the surface of a diaphragm substrate using a first polymer monomer solution may include, but is not limited to, spray coating, blade coating, or printing. The solvent of the first polymer monomer solution may be a solvent capable of effectively dissolving the first polymer monomer, and may be an oil-phase solvent or an aqueous-phase solvent. In the examples, if an oil-phase solvent is used, it may include, but is not limited to, at least one of the following solvents: aromatic compounds (such as, but not limited to, benzene, toluene, xylene, nitrobenzene, nitrobenzene, benzyl alcohol, benzoic acid, naphthalene, anthracene, phenanthrene, pyrene), aliphatic compounds (such as, but not limited to, n-hexane, cyclohexane, n-heptane), alcohols, and halogenated hydrocarbons (such as, but not limited to, carbon tetrachloride, chloroform); if an aqueous-phase solvent is used, it may be water, a buffer solution, etc.

[0138] In the exemplary example, the first polymer monomer may include at least one of trimellitic acid chloride (TMC), diphenyl carbonate (DPC), terephthalic acid (PTA), toluene diisocyanate (TDI), and isophthaloyl chloride (IPC). This first polymer monomer can undergo interfacial polymerization with the second polymer monomer in step S13 to generate an organic porous membrane layer, such as a fibrous polymer, possessing a rich three-dimensional pore structure, high porosity, and a pore diameter range as described above. It is also rich in polar groups, effectively improving the active ion conductivity of the organic porous membrane layer and enhancing the compatibility of the active ion flux of the membrane in this embodiment with the active ion insertion rate of the negative electrode material. Based on the solubility properties of the first polymer monomer, the solvent of the first polymer monomer solution includes an oil-phase solvent.

[0139] In this embodiment, before the first polymer monomer solution forms the first wet film layer on the surface of the diaphragm substrate, a surface treatment of the diaphragm substrate surface is further included. In an exemplary example, this surface treatment may include at least one of cleaning, ionization treatment, etc. The cleaning treatment can remove impurities from the surface of the diaphragm substrate. The ionization treatment can modify the surface of the diaphragm substrate, improving the film-forming properties of the first polymer monomer solution on the modified diaphragm substrate surface, improving the uniformity of the first wet film layer, and enhancing the mechanical strength of the final organic porous membrane layer bonded to the diaphragm substrate surface.

[0140] In step S12, an inorganic polymerization inhibitor is provided on the outer surface of the first wet film layer. This inhibitor can effectively regulate the interfacial polymerization reaction rate between the first wet film layer and the second wet film layer during the interfacial polymerization reaction process in step S14, thereby generating the organic porous film layer mentioned above, such as having through pores with a specific pore size range, and improving the synergistic effect of the formed organic porous film layer and the membrane substrate in regulating the flux of active ions.

[0141] In this embodiment, the inorganic polymerization inhibitor is fibrous. Thus, this fibrous inorganic polymerization inhibitor can effectively improve its effect on regulating the interfacial polymerization rate, while also acting as a template agent, enabling the interfacial polymerization reaction to generate organic fibers—specifically, fibrous polymers—and form a three-dimensional fibrous membrane.

[0142] In this embodiment, the inorganic polymerization inhibitor is ideally uniformly distributed on the outer surface of the first wet membrane layer. This ensures that the formed organic porous membrane layer, specifically the three-dimensional fiber membrane layer, has a relatively uniform distribution in terms of thickness, porosity, and pore diameter, thereby enhancing the synergistic effect of the organic porous membrane layer and the membrane substrate in regulating the flux of active ions.

[0143] In the embodiments, the inorganic polymerization inhibitor can be dispersed on the outer surface of the first wet film layer at a mass ratio of 1:(0.001 to 0.05) between the first polymer monomer and the inorganic polymerization inhibitor. The mass ratio of the first polymer monomer to the inorganic polymerization inhibitor can be further 1:(0.01 to 0.03). In exemplary examples, typical but non-limiting mass ratios such as 1:0.001, 1:0.005, 1:0.01, 1:0.015, 1:0.02, 1:0.025, 1:0.03, 1:0.035, 1:0.04, 1:0.045, and 1:0.05, or any range between two mass ratios, are possible. By controlling the dispersion amount of the inorganic polymerization inhibitor on the outer surface of the first wet membrane layer, the effect of the inorganic polymerization inhibitor in regulating the interfacial polymerization reaction rate in S14 can be improved. At the same time, the diameter of the fibrous polymer generated by the interfacial polymerization reaction can be adjusted, and the uniformity of the porosity and pore size of the generated organic porous membrane layer can be improved, thereby further enhancing the synergistic effect of the organic porous membrane layer and the membrane substrate in regulating the flux of active ions.

[0144] In the embodiments, the inorganic polymerization inhibitor can be the inorganic fibers contained in the organic porous membrane layer of the diaphragm in the above-described embodiments. That is to say, after the interfacial polymerization reaction in step S14, the inorganic polymerization inhibitor added in step S12 can remain in the organic porous membrane layer, so that the inorganic polymerization inhibitor can play a role in modifying the organic porous membrane layer. Thus, based on adjusting the rate of the interfacial polymerization reaction in step S14, it can further participate in adjusting the pore structure of the organic porous membrane layer, especially the diameter of the through pores, and further improve the synergistic effect of the organic porous membrane layer and the diaphragm substrate in regulating the flux of active ions; at the same time, it improves the mechanical properties of the organic porous membrane layer.

[0145] Therefore, in the embodiments, the inorganic polymerization inhibitor may be the inorganic fiber contained in the organic porous membrane layer in the membrane of the above-described embodiments. In the embodiments, the aspect ratio of the inorganic polymerization inhibitor is (10 to 1000):1. In the exemplary examples, it may be a typical but non-limiting aspect ratio such as 10:1, 50:1, 100:1, 300:1, 500:1, 800:1, 1000:1, or any range between two aspect ratios.

[0146] In the embodiments, the length of the inorganic polymerization inhibitor can be 0.1 to 5 μm, optionally 0.5 to 3 μm. In the exemplary examples, it can be a typical but non-limiting length such as 0.1 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or any range between two length values.

[0147] In the embodiments, the diameter of the inorganic polymerization inhibitor is 5 to 100 nm, and can be selected as 10 to 80 nm. In the exemplary examples, it can be a typical but non-limiting length such as 5 nm, 8 nm, 12 nm, 16 nm, 20 nm, 30 nm, 50 nm, 80 nm, 100 nm, or any range between two length values.

[0148] In the example, the inorganic polymerization inhibitor includes at least one of silicon dioxide, titanium dioxide, alumina, silicon carbide, and boron carbide. Of course, it may also contain other polymerization inhibitors, such as commonly used organic polymerization inhibitors.

[0149] By controlling the aspect ratio, diameter, length, and type of the inorganic polymerization inhibitor within the aforementioned ranges, the roles of the polymerization inhibitor and the interfacial polymerization reaction template agent can be further enhanced. This allows for adjustment of the interfacial polymerization reaction rate in step S14, as well as the aspect ratio of the generated fibrous polymer. Consequently, the pore structure of the generated organic porous membrane can be adjusted and improved, such as by further increasing the porosity and pore diameter of the organic porous membrane. This further enhances the synergistic effect between the organic porous membrane and the membrane substrate in regulating the flux of active ions and the mechanical properties of the membrane.

[0150] In the embodiments, the inorganic polymerization inhibitor can be directly applied to the surface of the first wet film as a solid, including by spraying or other methods. Alternatively, it can be prepared as an inorganic polymerization inhibitor solution and dispersed on the surface of the first wet film by spraying or other methods.

[0151] In step S13, the second polymer monomer solution should contain another monomer of the organic polymer contained in the organic porous membrane layer. The concentration of the second polymer monomer solution should be conducive to the formation of a second wet film on the surface of the first wet film layer containing the inorganic polymerization inhibitor. For example, in the embodiments, the mass percentage of the second polymer monomer in the second polymer monomer solution can be 5% to 35%. In exemplary examples, it can be a typical but non-limiting mass percentage such as 5%, 10%, 15%, 20%, 25%, 30%, or 35%, or a range between any two mass percentage values. This range of mass percentages can improve the membrane quality of the second wet film layer formed by the second polymer monomer solution, such as improving the uniformity and other membrane properties of the second wet film layer.

[0152] In the embodiments, the amount of the second wet film layer formed on the surface of the first wet film layer containing the inorganic polymerization inhibitor can be such that the thickness of the second wet film layer formed in step S14 is the same as the thickness range of the organic porous film layer contained in the diaphragm of the above-mentioned application embodiment, such as making the thickness of the organic porous film layer formed 5 to 30 nm.

[0153] The amount of the second wet film layer formed is specifically determined by the amount of the first polymer monomer in the first wet film layer. For example, the amount of the second wet film layer can be adjusted according to the molar ratio of the polymer reaction between the first polymer monomer in the first wet film layer and the second polymer monomer in the second wet film layer. In the embodiment, the amount of the second wet film layer formed can be such that the mass ratio of the first polymer monomer in the first wet film layer to the second polymer monomer in the second wet film layer is 1:(0.3 to 0.9) on the surface of the first wet film layer containing the inorganic polymerization inhibitor. The mass ratio of the first polymer monomer to the second polymer monomer can be further 1:(0.5 to 0.7). In exemplary examples, it can be a typical but non-limiting mass ratio such as 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, or any range between two mass ratios. By controlling the amount of the second wet film layer, under the action of the inorganic polymerization inhibitor in step S12, it undergoes an interfacial polymerization reaction with the first polymer monomer in the first wet film layer to generate an organic porous film layer, thereby improving the porosity distribution and thickness uniformity of the organic porous film layer and improving the quality of the organic porous film layer.

[0154] Based on the second wet film layer in step S13, a composite wet film is formed with the first wet film layer formed in step S11 and the inorganic polymerization inhibitor dispersed on the surface of the first wet film layer in step S12. At this time, the inorganic polymerization inhibitor is dispersed between the interface of the first and second wet film layers. Similarly, based on the amount of the first wet film layer formed in step S11, the content of the inorganic polymerization inhibitor on the surface of the first wet film layer in step S12, and the amount of the second wet film layer in step S13, in some embodiments, the mass ratio of the first polymer monomer in the first wet film layer, the second polymer monomer in the second wet film layer, and the inorganic polymerization inhibitor disposed between the first and second wet film layers can be 1:(0.3~0.9):(0.001~0.05). By controlling the mass ratio of the three components within this range, the interfacial polymerization rate of the first polymer monomer and the second polymer monomer in step S14 can be adjusted, thereby adjusting the polymer generation rate, the morphology of the generated polymer (e.g., fibrous polymer), and the aspect ratio of the generated fibrous polymer. This allows for adjustment of the porosity and pore diameter of the generated organic porous membrane, while also improving the uniformity of the organic porous membrane, including membrane thickness and porosity, thus enhancing the membrane quality and further improving the synergistic effect of the organic porous membrane on regulating the flux of active ions between the membrane and the membrane substrate.

[0155] In this embodiment, the method for forming a second wet film layer on the surface of a first wet film layer containing an inorganic polymerization inhibitor using a second polymer monomer solution may include, but is not limited to, methods such as spray coating, blade coating, or printing. The method for forming the second wet film layer may be the same as or different from the method for forming the first wet film layer. The solvent for the second polymer monomer solution can be a solvent capable of effectively dissolving the second polymer monomer, such as an oil-phase solvent or an aqueous-phase solvent. However, it should be noted that the solvent for the second polymer monomer is incompatible with the solvent for the first polymer monomer. For example, if the solvent for the first polymer monomer is an oil phase, then the solvent for the second polymer monomer is an aqueous phase; conversely, if the solvent for the first polymer monomer is an aqueous phase, then the solvent for the second polymer monomer is an oil phase. This allows the first and second polymer monomers to undergo an interfacial polymer reaction, generating the aforementioned organic porous film layer.

[0156] In the exemplary embodiment, the second polymer monomer may include at least one of methyldipropanediol (MPD), bisphenol A (BPA), ethylene glycol (EG), ethylenediamine (EDA), and m-phenylenediamine (MPD). These types of second polymer monomers can undergo interfacial polymerization with the first polymer monomer in step S11 to generate an organic porous membrane layer, such as a fibrous polymer, possessing a rich three-dimensional pore structure, high porosity, and pore diameter within the range described above. Furthermore, it is rich in polar groups, effectively improving the active ion conductivity of the organic porous membrane layer and enhancing the compatibility of the active ion flux of the membrane in this embodiment with the active ion insertion rate of the negative electrode material. Based on the solubility of the second polymer monomer, the solvent for the second polymer monomer solution can be an aqueous solvent, such as water or a buffer solution.

[0157] Furthermore, the second polymer monomer can be adjusted according to the type of the first polymer monomer. For example, when the first polymer monomer includes pyromellitic trimethylol chloride, the second polymer monomer may include methyl propylene glycol, and polyamide is generated after interfacial polymerization. When the first polymer monomer includes diphenyl carbonate (DPC), the second polymer monomer may include bisphenol A (BPA), and polycarbonate is generated after interfacial polymerization. When the first polymer monomer includes terephthalic acid (PTA), the second polymer monomer may include ethylene glycol (EG), and polyphenylene ester (poly(p-hydroxybenzoate)) is generated after interfacial polymerization. When the first polymer monomer includes toluene diisocyanate (TDI), the second polymer monomer may include ethylenediamine (EDA), and polyurea is generated after interfacial polymerization. When the first polymer monomer includes isophthaloyl chloride (IPC), the second polymer monomer may include m-phenylenediamine (MPD), and poly(m-phenylenediamine isophthalamide) is generated after interfacial polymerization.

[0158] Secondly, the first polymer monomer and the second polymer monomer mentioned above are interchangeable. That is, the first polymer monomer can be replaced by the second polymer monomer as described above, and the second polymer monomer can be replaced by the first polymer monomer as described above.

[0159] Of course, at least one of the above-mentioned first polymer monomer solution and second polymer monomer solution may also be added to the solution according to the type of polymer monomer contained therein, such as at least one of dispersant, initiator, catalyst, etc.

[0160] Based on the aforementioned first polymer monomer and its solvent, and second polymer monomer and its solvent, during the interfacial polymerization reaction in step S14, the first polymer monomer and second polymer monomer undergo interfacial polymerization at the interface between the first and second wet film layers. Since the inorganic polymerization inhibitor set in step S12 is dispersed between the interface of the first and second wet film layers, during the interfacial polymerization reaction, this inorganic polymerization inhibitor will regulate the rate of the interfacial polymerization reaction between the first and second polymer monomers at the interface of the first and second wet film layers. It will also affect the morphology of the polymer, generating a porous polymer structure, such as a three-dimensional fibrous polymer. At this time, the first and second polymer monomers that have not yet undergone interfacial polymerization will enter the generated porous polymer structure and continue to undergo interfacial polymerization. As the interfacial polymerization reaction continues, the pore size of the porous polymer structure can be continuously adjusted, resulting in a final organic porous membrane layer with a porous structure and pore diameters in the nanometer range of 0.5–10 nm. Simultaneously, the generated organic porous membrane layer exhibits uniform pore size and thickness, and high porosity. When the inorganic polymerization inhibitor is fibrous, the resulting polymer can also be fibrous, and the resulting organic porous membrane is a three-dimensional fibrous membrane. In this case, the three-dimensional fibrous membrane has a rich and uniform three-dimensional pore structure.

[0161] In this embodiment, the temperature of the interfacial polymerization reaction can be 40°C to 70°C. In the exemplary example, typical but non-limiting temperatures such as 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, and 70°C, or any range between two temperature values, can be used. This range of interfacial polymerization reaction temperature can be used in conjunction with an inorganic polymerization inhibitor to adjust the interfacial polymerization rate between the first and second polymer monomers, thereby adjusting the porous structure of the final organic porous membrane layer. This includes adjusting porosity and pore diameter, thereby enhancing the pore-regulating function of the organic porous membrane layer on the membrane substrate surface. This strengthens the synergistic effect of the membrane layer on regulating the active ion flux, improving the active ion flux of the prepared membrane, mitigating adverse phenomena such as crystallization and further dendrite formation at the negative electrode interface, and ultimately improving the safety of the battery cell.

[0162] In addition, the interfacial polymerization reaction should be sufficient. For example, at the interfacial polymerization reaction temperature of 40℃ to 70℃, the interfacial polymerization reaction time can be controlled to be 5 to 15 seconds to ensure that the first polymer monomer and the second polymer monomer undergo sufficient interfacial polymerization reaction.

[0163] Of course, besides using the above-described interfacial polymerization method to form an organic porous membrane layer on at least one surface of the membrane substrate, other methods can also be used to form an organic porous membrane layer on at least one surface of the membrane substrate. For example, in the embodiments, the above-described organic porous membrane layer can be prepared separately first, and then the organic porous membrane layer can be bonded to at least one surface of the membrane substrate to obtain a membrane.

[0164] Battery:

[0165] Thirdly, embodiments of this application also provide a battery.

[0166] In the embodiments of this application, the battery may include any one of a battery cell, a battery module, or a battery pack.

[0167] Battery cell:

[0168] A battery cell, also known as a battery pack, refers to the battery including its outer packaging and the electrode assembly encapsulated within it. A battery cell can contain one or more electrode assemblies, which can be adjusted according to actual needs.

[0169] The outer packaging of the battery cell can be a hard shell, such as a hard plastic shell, aluminum shell, or steel shell; or it can be a soft package, such as a pouch. The soft package material can be plastic, such as polypropylene, polybutylene terephthalate, or polybutylene succinate. The shape of the outer packaging can be cylindrical, square, or any other arbitrary shape. This outer packaging shape determines the shape of the battery cell; therefore, the shape of the battery cell can also be cylindrical, square, or any other arbitrary shape corresponding to the shape of the outer packaging. In the example, the battery cell can be as follows: Figure 3 The shown is a square-structured battery cell 20.

[0170] In some embodiments, such as Figure 4 As shown, the outer packaging of the battery cell 20 may include a housing 21 and a cover plate 23. The housing 21 may include a base plate and side plates connected to the base plate, the base plate and side plates enclosing a receiving cavity. The housing 21 has an opening communicating with the receiving cavity, and the cover plate 23 is used to cover the opening to close the receiving cavity. One or more electrode assemblies 22 are encapsulated within the receiving cavity.

[0171] In this embodiment, the battery cell can be a liquid battery cell containing a separator, or a semi-solid battery cell containing a separator and a solid electrolyte. It can also be a lithium-ion battery cell or a sodium-ion battery cell.

[0172] Regardless of whether the battery cell in this application is a liquid battery cell or a semi-solid battery cell, the electrode assembly contained in the battery cell in this application typically includes a positive electrode, a negative electrode, and a separator. The positive and negative electrode cells are alternately stacked, and the separator is stacked between the positive and negative electrode cells to provide isolation, separating them. The positive electrode, separator, and negative electrode can be formed into a stacked electrode assembly using a lamination process, or into a wound electrode assembly using a winding process. The electrode assembly containing the separator is placed in an outer packaging, injected with electrolyte to wet the electrode assembly, and then packaged to obtain the battery cell.

[0173] In this application, the separator in the battery cell is the same as the separator described in the previous application. Thus, the separator in the battery cell of this application can effectively regulate the flux of active ions migrating to the negative electrode, ensuring that the amount of active ions migrating to the negative electrode per unit time matches the active ion insertion rate of the negative electrode material. This significantly alleviates the problems of crystallization and dendrite formation at the negative electrode interface caused by the large accumulation of active ions migrating to the interface per unit time in existing cells. Furthermore, the separator in this application can effectively mitigate dendrite formation at the negative electrode interface and reduce the probability of dendrites growing towards the positive electrode, thereby lowering the probability of separator puncture. Therefore, the safety of the battery cell in this application is significantly improved.

[0174] In the embodiments, when the battery cell of this application embodiment is a semi-solid battery cell, that is, when the battery cell of this application embodiment contains a solid electrolyte in addition to a separator, the solid electrolyte contained in the battery cell may include at least one of polymer solid electrolyte, oxide electrolyte, sulfide electrolyte, borohydride electrolyte, composite solid electrolyte, etc.

[0175] In each of the above-mentioned battery cells, the positive electrode sheet contained in the battery cell of the present application embodiment includes a positive electrode current collector and a positive electrode active material layer bonded to at least one surface of the positive electrode current collector.

[0176] In the embodiments of this application, the positive electrode current collector contained in the positive electrode sheet of the battery cell may include, but is not limited to, metal current collectors, carbon current collectors, conductive resin current collectors, and composite current collectors of metal and resin, and more specifically, aluminum, copper, nickel, titanium, iron and their respective alloys, stainless steel, carbon fiber, carbon nanotubes (CNTs), graphite, etc. In the embodiments, the current collector may also be a dense film layer or a porous film layer. In the embodiments, the current collector may be, but is not limited to, aluminum foil or porous aluminum foil.

[0177] In this embodiment, the positive electrode active material layer contained in the positive electrode sheet may be bonded to one surface of the positive electrode current collector, or it may be bonded to two opposing surfaces of the positive electrode current collector. When the surface layer of the positive electrode current collector has a porous structure or the positive electrode current collector itself has a porous structure, the positive electrode active material layer may be at least partially embedded in the current collector.

[0178] In the embodiments, the mass percentage of the positive electrode active material in the positive electrode active material layer of the above-mentioned positive electrode sheet can be 90% to 98%, optionally 92% to 96%. In exemplary examples, it can be typical but non-limiting contents such as 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, and 98%, or any range between two contents. Positive electrode active material within this content range can effectively improve the energy density of the positive electrode sheet.

[0179] In the embodiments, the positive electrode active material may include sodium-ion positive electrode active material or lithium-ion positive electrode active material. When containing sodium-ion positive electrode active material, the battery cell in this application embodiment may be a sodium battery cell; when containing lithium-ion positive electrode active material, the battery cell in this application embodiment may be a lithium battery cell. In the exemplary embodiment, the sodium-ion positive electrode active material may include one or more of sodium layered oxides, polyanionic compounds, and Prussian blue compounds. In the exemplary embodiment, the lithium-ion positive electrode active material may include, but is not limited to, at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, and ternary materials. These types of sodium-ion positive electrode active materials or lithium-ion positive electrode active materials have high specific capacity, or further have high structural stability and good cycle performance.

[0180] In the embodiments, the positive electrode active material layer contained in the above-mentioned positive electrode sheet generally includes components such as binders and conductive agents in addition to the positive electrode active material components mentioned above. The binder can enhance the mechanical properties between the positive electrode active material layer itself and the current collector. The conductive agent can effectively improve the conductivity of the positive electrode sheet. In the exemplary example, the binder and conductive agent contained in the positive electrode sheet can be the binder and conductive agent in the negative electrode sheet of the above-mentioned application embodiments, respectively. To save space, the binder and conductive agent will not be described in detail here.

[0181] In each of the above-mentioned battery cells, the negative electrode sheet contained in the battery cell of the present application embodiment includes a negative electrode current collector, and optionally may also include a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, the negative electrode active material layer containing a negative electrode active material.

[0182] In the embodiments of this application, the negative electrode current collector contained in the negative electrode sheet of the battery cell may include, but is not limited to, metal or composite current collectors. For example, as a metal, sodium, sodium alloy, lithium, lithium alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc. may be used. When sodium or sodium alloy is used as the negative electrode current collector, sodium or sodium alloy itself can also serve as a negative electrode active material; similarly, when lithium or lithium alloy is used as the negative electrode current collector, lithium or lithium alloy itself can also serve as a negative electrode active material; therefore, the negative electrode sheet may not contain a negative electrode active material layer, and sodium, sodium alloy or lithium, lithium alloy serves as both the current collector and the negative electrode active material.

[0183] Composite current collectors can include composite materials of polymers and metals. In the embodiments, the polymers may include, but are not limited to, polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE). In the embodiments, the metals may include, but are not limited to, sodium, lithium, copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Composite current collectors can be obtained by blending polymers and metals, or they can be coated onto at least one side of the polymer material through electroplating, coating, or other methods.

[0184] When the negative electrode includes a negative electrode active material layer, the negative electrode active material in the negative electrode active material layer may be a mixture or composite material formed from any one or more of carbon-based materials, alloy materials, titanium-based materials, sodium metal, and lithium metal. Specifically, carbon-based materials include, but are not limited to, one or more of graphite, soft carbon, hard carbon, carbon microspheres, and carbon fibers; alloy materials include, but are not limited to, one or more of sodium-tin alloys, sodium-germanium alloys, and sodium-antimony alloys, or alloy materials include, but are not limited to, one or more of lithium-tin alloys, lithium-germanium alloys, and lithium-antimony alloys; and titanium-based materials include, but are not limited to, one or more of titanium dioxide, titanates, and titanium phosphates.

[0185] The mass percentage of the negative electrode active material in the negative electrode active material layer can be 85% to 98%, and can be selected as 95% to 98%. In the example, it can be a typical but non-limiting content such as 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or any range between two content values.

[0186] The negative electrode active material layer may also include at least one of a conductive agent and a binder. The conductive agent is used to collect current between the negative electrode active materials and between the active materials and the current collector, thereby improving electronic conductivity. Simultaneously, the conductive agent can also promote the wetting of the negative electrode sheet by the electrolyte. The binder can improve the bonding strength between the substances in the negative electrode active material layer and between the negative electrode active material layer and the current collector.

[0187] In the embodiments, the mass percentage of the conductive agent in the negative electrode active material layer can be 0.5% to 10%. In exemplary cases, it can be a typical but non-limiting content such as 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a range between any two content values. Other contents can also be set as needed. In exemplary cases, the conductive agent includes one or more of acetylene black (SP), carbon nanotubes, conductive carbon black (super-P), Ketjen black, carbon fiber, and graphene.

[0188] In the embodiments, the mass percentage of the binder in the negative electrode active material layer can be 0.5% to 10%. In exemplary examples, it can be a typical but non-limiting content such as 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a range between any two content values. Other contents can also be set as needed. In exemplary examples, the binder includes, but is not limited to, one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, polyimide, polytetrafluoroethylene, polybutyl acrylate, polyacrylonitrile, carboxymethyl cellulose, carboxymethyl cellulose salt, polyacrylic acid, polyacrylate, polyvinyl alcohol, sodium alginate, cyclodextrin, styrene-butadiene rubber, vinyl acetate resin, acrylic resin, and chlorinated rubber.

[0189] In the embodiments, the negative electrode active material layer may optionally include a thickener, such as, but not limited to, carboxymethyl cellulose (CMC). The mass percentage of the thickener in the negative electrode active material layer can be set to 0.5% to 5%, and in exemplary examples, it can be a typical but non-limiting content such as 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or a range between any two content values.

[0190] Battery module:

[0191] When the battery in the embodiments of this application is a battery module, the battery module refers to the assembly of the above-mentioned battery cells, that is, it can contain multiple of the above-mentioned battery cells, and the specific number can be adjusted according to the application and capacity of the battery module.

[0192] In some embodiments, Figure 5 This is a schematic diagram of battery module 30 as an example. (See diagram below.) Figure 5 As shown, in the battery module 30, multiple battery cells 20 can be arranged sequentially along the length of the battery module 30. Of course, they can also be arranged in any other manner. Furthermore, the multiple battery cells 20 can be fixed in place using fasteners.

[0193] Optionally, the battery module 30 may also include a housing with a receiving space in which multiple battery cells 20 are received.

[0194] Battery pack:

[0195] When the battery in this application embodiment is a battery pack, the battery pack refers to the assembly of the aforementioned battery cells, that is, it can contain multiple battery cells, and these multiple battery cells are assembled into the aforementioned battery module. The specific number of battery cells or battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0196] In some embodiments, Figure 6 This is a schematic diagram of a battery pack 40 as an example. The battery pack 40 may include a battery compartment and multiple battery modules 30 disposed within the battery compartment. The battery compartment includes an upper compartment 41 and a lower compartment 42. The upper compartment 41 covers the lower compartment 42, forming a closed space for accommodating the battery modules 30. The multiple battery modules 30 can be arranged in any manner within the battery compartment.

[0197] Electrical appliances:

[0198] Fourthly, this application also provides an electrical device. The electrical device of this application includes a power supply unit or an energy storage unit, and may also include other auxiliary or necessary components. The power supply unit or energy storage unit contains the battery described in the above application embodiment. For example, it may be a single battery cell, a battery module, or a battery pack. Because the electrical device of this application embodiment contains the battery described in the above application embodiment, the power supply unit or energy storage unit of the electrical device of this application embodiment has high safety and a long service life, and the standby or battery life of the electrical device of this application embodiment is long.

[0199] In this embodiment, the electrical device may include, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys may include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft may include airplanes, rockets, space shuttles, and spacecraft, etc. As an electrical device, the battery cells, battery modules, or battery packs can be selected according to their usage requirements.

[0200] Figure 7 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0201] In this embodiment, when the electrical device includes an energy storage unit, the electrical device can be an energy storage device, which includes the energy storage unit and may also include other auxiliary or necessary components. The energy storage unit contains the battery described in the above-described embodiment. The energy storage unit may contain one or more batteries. When there are multiple batteries, they can form a battery module or battery pack. Because the energy storage device in this embodiment includes the battery described in the above-described embodiment, the energy storage device has high safety, good cycle performance, and a long service life.

[0202] Example:

[0203] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0204] 1. Examples of diaphragm and its preparation method:

[0205] Example A1:

[0206] This embodiment A1 provides a separator and its preparation method. The separator includes a polyethylene membrane substrate (base membrane), and an organic porous membrane layer is disposed on one surface of the polyethylene membrane substrate. The organic porous membrane layer is a three-dimensional polyamide fiber interface membrane layer (three-dimensional PA fiber layer), in which nanowire silica is dispersed. The relevant characteristic parameters of the separator provided in Embodiment A1 are shown in Table 1 below.

[0207] The membrane preparation method includes the following steps:

[0208] S1: Plasma treatment is performed on the surface of the polyethylene film substrate using a plasma beam to obtain a plasma-treated polyethylene film substrate.

[0209] S2: A 20% TMC oily solution is sprayed onto the plasma-treated surface of a polyethylene film substrate to form a wet TMC film.

[0210] S3: Spray a layer of nanowire silica (silica fiber) onto the surface of the TMC wet film away from the polyethylene film substrate.

[0211] S4: An aqueous solution with a mass concentration of 20% MPD is sprayed onto the surface of a TMC wet film containing dispersed nanowire silica to form an MPD wet film;

[0212] S5: The polyethylene film substrate with TMC wet film and MPD wet film formed on the surface is heated to 50℃+5℃ to carry out interfacial polymerization reaction. The TMC wet film and MPD wet film generate a three-dimensional PA fiber layer under the action of nanowire silica to obtain the diaphragm.

[0213] In the formation of TMC wet film and MPD wet film, the mass ratio of TMC in TMC wet film and MPD and nanowire silica in MPD wet film is 1:0.5:0.01.

[0214] Examples A2 to A11:

[0215] Examples A2 to A11 each provide a diaphragm and its preparation method.

[0216] Among them, the diaphragms in Examples A2 to A5 differ from those in Example A1 in that the diameter of the through-pores contained in the three-dimensional polyamide fiber layer is different, resulting in differences in the porosity and other properties of the diaphragms.

[0217] The diaphragms in Examples A6 to A8 differ from those in Example A3 in that the thickness of the three-dimensional polyamide fiber layer is different, resulting in differences in the thickness, porosity, and other properties of the diaphragms.

[0218] The membranes in Examples A9 to A11 differ from those in Example A1 in that they are made of different materials, have different thicknesses, and contain different diameters of the porous organic membrane layers, resulting in differences in membrane thickness and porosity. Specifically, Example A11 does not contain nanowire silica, unlike Example A1.

[0219] The diaphragm-related characteristic parameters in Examples A2 to A11 are shown in Table 1 below.

[0220] The membrane preparation methods in Examples A2 to A11 are the same as those in Example A1. The differences are that the materials and conditions of the corresponding steps are adjusted according to the membrane material and membrane properties in each example. For example, in Examples A9 to A11, when preparing the organic porous membrane, the polymer monomers in steps S2 and S4 are replaced according to the type of polymer contained in the organic porous membrane of the corresponding example.

[0221] Comparative Example A1 and Comparative Example A2:

[0222] Comparative Examples A1 and A2 respectively provide a diaphragm and its preparation method.

[0223] The diaphragms in Comparative Examples A1 and A2 differ from those in Example A1 in that the diameters of the pores in the three-dimensional polyamide fiber layers are different, resulting in differences in the porosity and other properties of the diaphragms. The relevant characteristic parameters of the diaphragms in Comparative Examples A1 and A2 are shown in Table 1 below.

[0224] The diaphragm preparation methods in Comparative Examples A1 and A2 are the same as those in Example A1.

[0225] Comparative Example A3:

[0226] Comparative Example A3 provides a diaphragm, which is the diaphragm substrate of Example A1. That is, compared with the diaphragm in Example A1, it does not contain an organic porous membrane layer.

[0227] 2. Performance tests of the diaphragm in each embodiment:

[0228] The diaphragms provided in Examples A1 to A11 and Comparative Examples A1 to A3 were subjected to the relevant feature detection methods shown in Table 1 below, and the results are shown in Table 1. The relevant feature detection methods for the diaphragms in Table 1 are as follows:

[0229] Thickness detection method for organic porous membranes and diaphragms: X-ray photoelectron spectroscopy (XPS) was used for detection;

[0230] Porosity detection method (nitrogen adsorption method): First, place the membrane sample into the sample device of the ammonia adsorption instrument, then turn off the device and evacuate it using a vacuum pump. After the vacuum stabilizes, set the required test parameters, including temperature, test mode, and equilibrium time, through the control panel of the ammonia adsorption instrument. Then, turn on the gas pump and its control switch to allow ammonia to enter the test tube until the required pressure range is reached. After maintaining this pressure for a period of time, turn off the vacuum pump, open the sample chamber door, and allow nitrogen to enter the sample pores. Finally, based on the pressure and temperature changes recorded by the nitrogen adsorption instrument during the adsorption and desorption processes, the porosity and pore size of the membrane can be calculated using the specific surface area equation and pore size distribution model.

[0231] Method for detecting the diameter of pores in organic porous membranes: Scanning electron microscopy (SEM) is used to measure the diameter range of the pores based on the SEM images. The SEM image of the diaphragm in Example A8 is shown below. Figure 8 As shown. Among them, Figure 8 Figure a shows an SEM image of the organic porous membrane layer in the diaphragm of Example A8, and Figure b shows an SEM image of the diaphragm substrate in Example A8. The SEM images show that the organic porous membrane layer on the diaphragm surface is a three-dimensional nanofiber membrane. Its pore structure and size are significantly improved compared to the polyolefin-based membrane (diaphragm substrate), overcoming defects such as micropores and pinholes present in the diaphragm substrate.

[0232] Table 1

[0233]

[0234] 3. Example of a single lithium-ion battery cell:

[0235] Examples B1 to B11 and Comparative Examples B1 to B3:

[0236] Examples B1 to B11 and Comparative Examples B1 to B3 each provide a lithium-ion battery cell. Each lithium-ion battery cell includes an electrode assembly formed by a positive electrode, a separator, and a negative electrode, and also includes an electrolyte.

[0237] The lithium-ion battery cells in Examples B1 to B11 and Comparative Examples B1 to B3 are assembled as follows:

[0238] Positive electrode sheet: Lithium iron phosphate, conductive carbon black, and binder polyvinylidene fluoride (PVDF) are mixed thoroughly in an appropriate amount of solvent N-methylpyrrolidone at a weight ratio of 8:1:1 to form a uniform positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of a 13μm positive electrode current collector aluminum foil. After drying and cold pressing, it is cut to obtain the positive electrode sheet. The positive electrode sheet is rolled into a film roll, and a ceramic slurry is sprayed onto the cut surface of the film roll. In the ceramic slurry, the ceramic material is boehmite, accounting for 39wt%; the binder is polyacrylate, accounting for 5wt%; the solvent is N-methylpyrrolidone; the solid content of the slurry is 10%; and the viscosity of the slurry is 8000mPa·s.

[0239] Negative electrode sheet: Artificial graphite, conductive carbon black, binder carboxymethyl cellulose (CMC) and solvent water are thoroughly mixed in a weight ratio of 95:2:3:100 to obtain a uniform negative electrode slurry; the negative electrode slurry is uniformly coated on both surfaces of a 6μm copper foil, dried, cold-pressed, and then cut to obtain the negative electrode sheet;

[0240] 3) Separator: The separators provided in Examples A1 to A11 and Comparative Examples A1 to A2 are used as separators; wherein, the cell in Example B1 contains the separator in Example A1, the cell in Example B2 contains the separator in Example A2, and so on, and the cell in Comparative Example B3 contains the separator in Comparative Example A3.

[0241] 4) Electrolyte: Vinyl acetate, diethyl carbonate, and dimethyl carbonate are mixed in a volume ratio of 1:1:1. LiPF6 is dissolved in the above solution to obtain the electrolyte; the concentration of LiPF6 in the electrolyte is 1 mol / L.

[0242] 5) Battery Assembly: The positive electrode, separator, and negative electrode are stacked sequentially, with the separator positioned between the positive and negative electrodes to provide isolation. The electrode assembly is then obtained through a winding process. Each electrode assembly is placed in an outer packaging, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping processes, the ion battery cells of Examples B1 to B11 and Comparative Examples B1 to B3 are obtained, respectively.

[0243] 4. Electrochemical performance testing of individual ion battery cells in each embodiment:

[0244] The ion battery cells provided in Examples B1 to B11 and Comparative Examples B1 to B3 were subjected to the relevant electrochemical performance tests listed in Table 2 below, using the methods described below. The results are shown in Table 2. The methods for testing the relevant performance of the ion battery cells in Table 2 are as follows:

[0245] High-temperature storage voltage drop: ① Charge the secondary battery to 4.25V at a constant current of 0.33C at 25℃, let it rest for 3 minutes, and test cell OCV1; ② Then store it in an environment of 45℃ for 60 days. After storage, cool the cell to 25℃ and test cell OCV2; ③ High-temperature storage voltage drop = OCV1 - OCV2.

[0246] Cycle life (number of cycles): The number of cycles is calculated by charging the secondary battery at a constant current of 0.33C to 4.25V at 25℃, then charging it at a constant voltage of 4.25V to a current of 0.05C, and then discharging it at a constant current of 1C to 2.8V.

[0247] Cell calendar life: ① Charge the secondary battery at a constant current of 0.33C to 4.25V at 25℃, ② then store it in a 45℃ environment for 30 days; ③ after 30 days of storage, charge it at a constant voltage of 4.25V until the current drops to 0.05C, then discharge it at a constant current of 0.33C to 2.8V, repeat this charge-discharge cycle until the 3rd cycle, and record the cell capacity retention rate; ④ if the capacity retention rate is >80% in the above steps, continue with ①-③, if the capacity retention rate is <80%, stop the test and record the total number of times step ② is performed, n; ⑤ calendar life = 30*n days.

[0248] Table 2

[0249]

[0250] Based on Table 1 and the data in Table 2, it can be seen that the high-temperature storage voltage drop, cell calendar life, and cell cycle life of the ion battery cells in Examples B1 to B11 are all higher than those in Examples B1 to B3. This indicates that the separator in Examples A1 to A11 significantly improves the high-temperature storage voltage drop, cell calendar life, and cell cycle life of the ion battery cells. Among them, the high-temperature storage voltage drop values ​​of the ion battery cells in Examples B1 to B11 containing the separators of Examples A1 to A11 are all lower than those of the ion battery cells in Comparative Examples B1 to B2 containing the separators of Comparative Examples A1 to A2, and even lower than those of the ion battery cells in Comparative Example B3 containing the separator of Comparative Example A3. This indicates that under the same conditions, the voltage of the ion battery cells is more stable. This shows that the pore size of the organic porous membrane layer contained in the separator of this application can regulate the pore size of the separator substrate. The organic porous membrane layer, together with the separator substrate, can effectively regulate the active ion flux, improve the compatibility between the active ion flux of the separator of this application and the active ion insertion rate of the negative electrode material, thereby effectively reducing the crystallization phenomenon in the cell and significantly reducing dendrite growth, thus making the high-temperature storage voltage drop value of the cell relatively stable. This effect is also indirectly illustrated by the cycle performance and cell calendar life data of the corresponding ion battery cells.

[0251] Referring to Table 1, further comparisons of Examples B1 to B5 and Comparative Examples B1 to B2 reveal that when the thickness of the organic porous film is similar, and the pore diameter of the organic porous film is in the range of 0.5 nm to 3 nm, the high-temperature storage voltage drop of the ion battery cell is relatively low, while the cell calendar life and cell cycle life are relatively high. As the pore diameter of the organic porous film continues to increase, the high-temperature storage voltage drop of the ion battery cell increases accordingly, while the cell calendar life and cell cycle life decrease accordingly. Within the range of 0.5 nm to 30 nm, the high-temperature storage voltage drop, cell calendar life, and cell cycle life of the ion battery cell can be significantly improved.

[0252] Comparing Example B5 and Comparative Examples B2 to B3, it can be seen that when the pore diameter of the organic porous membrane is too large (such as the pore diameter of the organic porous membrane contained in the ion battery cell in Comparative Example B2 or the separator of the ion battery cell in Comparative Example B3 that does not contain an organic porous membrane), the high-temperature storage voltage drop of the ion battery cell will increase significantly, and the performance of the cell calendar life and cell cycle life will decrease significantly. This indicates that when the pore diameter of the organic porous membrane is too large, the organic porous membrane and the separator substrate do not significantly regulate the active ion flux of the separator (the composite separator of the organic porous membrane and the separator substrate), and thus the effect of regulating the compatibility between the active ion flux of the separator and the active ion insertion rate of the negative electrode material is not significant.

[0253] Comparing Example B1 and Comparative Example B1, it can be seen that when the pore diameter of the organic porous membrane is too small (such as the pore diameter of the organic porous membrane contained in the ion battery cell in Comparative Example B1), although the high-temperature storage voltage drop of the ion battery cell is small, the performance of the cell calendar life and cell cycle life is significantly reduced. This indicates that the pore diameter of the organic porous membrane is too small, which generates a relatively large resistance to the transport of active ions, resulting in increased internal impedance and adversely affecting other electrochemical performance of the ion battery cell.

[0254] Comparing Examples B1, B9 to B11, it can be seen that when the polymer of the organic porous membrane layer is another polymer and an interfacial polymer membrane layer with a certain pore diameter range is formed, it can effectively regulate the active ion flux together with the membrane substrate, improve the compatibility between the active ion flux of the membrane in this application embodiment and the active ion insertion rate of the negative electrode material contained in the negative electrode, thereby effectively reducing crystallization and dendrite formation in the cell.

[0255] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A diaphragm, comprising a diaphragm substrate, characterized in that, It also includes an organic porous membrane layer disposed on at least one surface of the diaphragm substrate, wherein the organic porous membrane layer contains through pores with a diameter of 0.5 to 10 nm.

2. The diaphragm as described in claim 1, characterized in that: The diameter of the through hole is 0.5 to 3 nm.

3. The diaphragm as described in claim 1 or 2, characterized in that: The organic porous membrane layer includes at least one or more of the following (1) to (3): (1) The thickness of the organic porous membrane is 5-30 nm; (2) The porosity of the organic porous membrane layer is 0.5% to 80%; (3) The organic porous membrane is a three-dimensional fiber membrane consisting of organic fibers.

4. The diaphragm as described in claim 3, characterized in that: The thickness of the organic porous membrane layer is 8–20 nm; and / or The porosity of the organic porous membrane layer is 10% to 50%; and / or The organic fiber includes at least one or more of the following (1) to (4): (1) The aspect ratio of a single organic fiber is (2-5000):1; (2) The diameter of a single organic fiber is 2 to 100 nm; (3) The length of a single organic fiber is 50 nm to 10 μm; (4) In the three-dimensional fiber membrane, chemical bonds are formed in the contact portions of two adjacent organic fibers.

5. The diaphragm according to any one of claims 1 to 4, characterized in that: The organic material of the organic porous membrane contains at least one polar group selected from nitrogen-containing groups and oxygen-containing groups.

6. The diaphragm according to any one of claims 1 to 5, characterized in that: The organic material of the organic porous membrane layer includes at least one of polyamide, polycarbonate, polyphenylene ester, polyurea, and poly(m-phenylene isophthalamide); and / or The organic porous membrane contains inorganic fibers, and the inorganic fibers account for 0.05% to 3.84% of the organic porous membrane by mass.

7. The diaphragm as described in claim 6, characterized in that: The inorganic fibers in the organic porous membrane layer comprise 0.6% to 2.0% by mass; and / or The inorganic fiber includes at least one of the following (1) to (4): (1) The aspect ratio of the inorganic fiber is (10~1000):1; (2) The length of the inorganic fiber is 0.1–5 μm; (3) The diameter of the inorganic fiber is 5-100 nm; (4) The inorganic fiber includes at least one of silicon dioxide, titanium dioxide, aluminum oxide, silicon carbide, and boron carbide.

8. The diaphragm according to any one of claims 1 to 7, characterized in that: The diaphragm includes at least one of the following (1) to (2): (1) The thickness of the diaphragm is 5 to 50 μm; (2) The porosity of the diaphragm is 20% to 60%.

9. A method for preparing a diaphragm, characterized in that, Includes the following steps: An organic porous membrane layer is formed on at least one surface of a membrane substrate to obtain a membrane; The organic porous membrane layer formed contains through pores with a diameter of 0.5 to 10 nm.

10. The preparation method according to claim 9, characterized in that, The method for forming an organic porous membrane layer on at least one surface of a diaphragm substrate includes the following steps: A first wet film layer is formed on at least one surface of the diaphragm substrate by a first polymer monomer solution; An inorganic polymerization inhibitor is disposed on the surface of the first wet film layer opposite to the diaphragm substrate; A second wet film layer is formed on the surface of the first wet film layer where the inorganic polymerization inhibitor is disposed, by the second polymer monomer solution. The composite wet membrane formed by the first wet membrane layer and the second wet membrane layer is subjected to an interfacial polymerization reaction to generate the organic porous membrane layer. The inorganic polymerization inhibitor is fibrous.

11. The preparation method according to claim 10, characterized in that, The mass ratio of the first polymer monomer in the first wet film layer, the second polymer monomer in the second wet film layer, and the inorganic polymerization inhibitor disposed between the first wet film layer and the second wet film layer is 1:(0.3~0.9):(0.001~0.05); and / or In the first polymer monomer solution, the mass percentage of the first polymer monomer is 10% to 30%; and / or In the second polymer monomer solution, the mass percentage of the second polymer monomer is 5% to 35%; and / or The temperature of the interfacial polymerization reaction is 40℃~70℃.

12. The preparation method according to claim 10 or 11, characterized in that, The first polymer monomer includes at least one of pyromellitic phthaloyl chloride, diphenyl carbonate, terephthalic acid, toluene diisocyanate, and isophthaloyl chloride; and / or The second polymer monomer includes at least one of methylpropanediol, bisphenol A, ethylene glycol, ethylenediamine, and m-phenylenediamine; and / or The inorganic polymerization inhibitor includes at least one of the following (1) to (4): (1) The aspect ratio of the inorganic polymerization inhibitor is (10~1000):1; (2) The length of the inorganic polymerization inhibitor is 0.1–5 μm; (3) The diameter of the inorganic polymerization inhibitor is 5-100 nm; (4) The inorganic polymerization inhibitor includes at least one of silicon dioxide, titanium dioxide, aluminum oxide, silicon carbide, and boron carbide.

13. A battery, characterized in that, It includes the diaphragm according to any one of claims 1 to 8 or the diaphragm prepared by the preparation method according to any one of claims 9 to 12.

14. An electrical appliance, characterized in that: Includes the battery as described in claim 13.

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