Battery cell, related apparatus, system, and charging network

Abstract

The present application discloses a battery cell, a related apparatus, a system, and a charging network. The battery cell comprises a positive electrode sheet, a negative electrode sheet, and a separator located between the positive electrode sheet and the negative electrode sheet. The separator comprises a base film and a material coating arranged on at least one surface of the base film. The material coating comprises mesoporous fibrous materials and mesoporous particles, wherein at least some of the mesoporous fibrous materials and the mesoporous particles are mutually intercalated. In the present application, the material coating comprising the mesoporous fibrous materials and the mesoporous particles is provided on the separator, such that transition metal ions dissolved out of the positive electrode sheet can be effectively captured and the migration of the transition metal ions to the negative electrode sheet or an electrolyte is hindered, thereby effectively suppressing internal side reactions of the battery cell, enabling the battery to still maintain a high capacity after multiple charging and discharging cycles, and thus prolonging the cycle life of the battery cell.

Description

Battery cell, related device, system and charging network

[0001] This application claims priority to the Chinese patent application No. 202411352030.9, filed on September 26, 2024 in the China Patent Office, and entitled "Battery cell, related device, system and charging network", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of battery, in particular to a battery cell, related device, system and charging network. BACKGROUND

[0003] The statements herein are provided only to enhance understanding of the present application and are not necessarily intended to constitute the prior art.

[0004] In recent years, the application field of lithium ion battery is more and more extensive, such as energy storage power supply field of wind power, hydroelectric power, thermal power and solar power station, and multiple fields of electric bicycle, electric motorcycle, electric vehicle, aerospace and aviation. While the lithium ion battery has achieved great development, the requirement for its cycle performance is also increasingly stringent.

[0005] The lithium ion battery separator is an important component in the battery in addition to the positive material, negative material and electrolyte, which plays an important role in isolating the positive and negative electrodes and realizing electronic insulation and ionic conduction. Therefore, with the continuous improvement of the performance requirements of the battery, optimizing the separator to improve the cycle performance of the battery has become the focus of current research.

[0006] SUMMARY

[0007] The purpose of the embodiments of the present application is to provide a battery cell, related device, system and charging network, which includes but is not limited to solving the problem of unsatisfactory cycle performance of the battery cell.

[0008] The technical solution adopted by the embodiments of the present application is:

[0009] In a first aspect, a battery cell is provided, comprising a positive electrode sheet, a negative electrode sheet and a separator located between the positive electrode sheet and the negative electrode sheet, the separator comprising a base film and a material coating layer provided on at least one surface of the base film, the material coating layer comprising mesoporous fibrous substances and mesoporous particles, and at least part of the mesoporous particles being distributed between the mesoporous fibrous substances.

[0010] In the technical solution of the present application, a material coating including mesoporous fibrous substances and mesoporous particles is arranged on the diaphragm, and at least part of the mesoporous particles are distributed between the mesoporous fibrous substances. This is conducive to forming a mesoporous structure with specific pore distribution on the surface of the diaphragm. On the one hand, it can effectively capture transition metal ions dissolved from the positive electrode sheet, hinder the migration of transition metal ions to the negative electrode sheet or the electrolyte, thereby effectively inhibiting the occurrence of side reactions in the battery monomer. This enables the battery to maintain a high capacity after multiple charge and discharge cycles, thereby prolonging the cycle life of the battery monomer. On the other hand, the abundant mesoporous structure on the surface of the diaphragm greatly increases the contact area between the diaphragm and the electrolyte, improves the liquid retention capacity of the diaphragm, and enhances the diffusion performance of the electrolyte in the diaphragm. This helps to supplement the electrolyte consumed on the electrode surface in a timely manner during the charge and discharge process of the battery monomer, thereby reducing side reactions caused by insufficient electrolyte, and thus enabling the battery to exhibit high cycle performance.

[0011] In some embodiments, the mesoporous fibrous substances satisfy at least one of the following characteristics (1)-(4):

[0012] (1) The length of the mesoporous fibrous substances is 0.5-5 μm;

[0013] (2) The diameter of the mesoporous fibrous substances is 50-100 nm;

[0014] (3) The aspect ratio of the mesoporous fibrous substances is 10-100;

[0015] (4) The pore size of the mesoporous fibrous substances is 5-20 nm.

[0016] Controlling the length, diameter, and pore size of the mesoporous fibrous substances within the above ranges enables multiple mesoporous fibrous substances to be connected by interlacing each other to form a network structure containing an appropriate amount of mesoporous structure, thereby improving the mechanical properties of the diaphragm while improving the adsorption capacity of the diaphragm for transition metal ions.

[0017] In some embodiments, the morphology of the mesoporous fibrous substances includes at least one of rod-like, columnar, linear, tubular, rod-like, and fibrous, and the material of the mesoporous fibrous substances includes at least one of silicon oxide, aluminum oxide, and magnesium oxide.

[0018] A material with a suitable morphology is conducive to forming a more stable network structure of mesoporous fibrous substances in the material coating, thereby effectively improving the mechanical properties of the diaphragm, the adsorption performance for transition metal ions, and the wetting effect of the electrolyte, thereby improving the cycle life of the battery monomer.

[0019] In some embodiments, the mesoporous particles satisfy at least one of the following characteristics (1)-(4):

[0020] (1) the specific surface area of the mesoporous particles is 100-500 m 2 / g;

[0021] (2) the pore volume of the mesoporous particles is 0.2-0.6 cm 3 / mg;

[0022] (3) the particle size of the mesoporous particles is 50 nm-500 nm;

[0023] (4) the pore size of the mesoporous particles is 5 nm-20 nm.

[0024] Controlling the specific surface area, pore volume, particle size, and pore size of the mesoporous particles within the above ranges helps the mesoporous particles to be filled in the network structure and endow the separator with abundant mesoporous structure, thereby realizing effective adsorption of transition metal ions and improving the cycle performance of the battery cell.

[0025] In some embodiments, the mesoporous particles include at least one of mesoporous silicon oxide, mesoporous aluminum oxide, and mesoporous magnesium oxide.

[0026] The mesoporous particles have high chemical stability and inertness, which is more conducive to improving the safety of the battery cell.

[0027] In some embodiments, the surface of at least one of the mesoporous fibrous material and the mesoporous particles is connected with a chemical group, and the chemical group includes an amino group, a carboxyl group, and an ethylenediamine tetraethyl group.

[0028] By providing the chemical group in the separator, the adsorption capacity of the separator for the transition metal ions dissolved from the positive electrode sheet can be improved, the occurrence of side reactions in the battery cell can be reduced, and the cycle life of the battery cell can be improved.

[0029] In some embodiments, the material coating further includes solid particles, and the solid particles include at least one of silicon oxide, barium sulfate, boehmite, and montmorillonite.

[0030] The addition of the solid particles in the material coating can enhance the mechanical strength of the separator, so that the separator is not easy to break or deform during the assembly and use of the battery cell.

[0031] The solid particles have high chemical stability and inertness, and are not easy to increase the safety risk of the battery cell.

[0032] In some embodiments, the material coating further includes a binder, and the binder includes a water-soluble binder.

[0033] The addition of the binder in the material coating forms a firm combination between the material coating and the base film, preventing the material coating from falling off or peeling.

[0034] In some embodiments, the material coating includes a first coating layer, and the first coating layer includes mesoporous fibrous substances and mesoporous particles.

[0035] The material coating includes a first coating layer, that is, the separator includes a base film and a first coating layer arranged on at least one surface of the base film, and due to the fact that the first coating layer includes mesoporous fibrous substances and mesoporous particles, the first coating layer can effectively adsorb transition metal ions dissolved from the positive electrode plate, inhibit the occurrence of side reactions inside the battery cell, and thus effectively improve the cycle life of the battery cell.

[0036] In some embodiments, the material coating includes a first coating layer and a second coating layer stacked together, and the second coating layer includes mesoporous fibrous substances and mesoporous particles.

[0037] The positive electrode plate, the negative electrode plate, and the separator are in a wound structure, and the separator includes a plurality of flat regions and a plurality of corner regions alternately connected, and at least one corner region of the separator is provided with the second coating layer, and the second coating layer is arranged on the surface of the first coating layer away from the base film.

[0038] The material coating includes a first coating layer and a second coating layer stacked together, that is, the separator includes the base film, the first coating layer, and the second coating layer stacked together, and the first coating layer is located between the base film and the second coating layer, and due to the fact that the second coating layer is arranged in the corner region of the separator, it means that the corner region of the separator has abundant mesoporous structures, which not only helps to provide a smooth active ion transmission channel, but also improves the wetting capacity of the electrolyte of the separator, especially the electrolyte wetting capacity of the corner region, thereby reducing the problem of excessively high or low local active ion concentration and reducing the risk of lithium precipitation.

[0039] In some embodiments, the first coating layer and the second coating layer each independently include at least one of solid particles and a binder.

[0040] The solid particles can improve the mechanical properties of the first coating layer and the second coating layer, and the binder can improve the bonding force between the first coating layer, the second coating layer, and the base film, so that the separator is not easily damaged during the charging and discharging process of the battery cell.

[0041] In some embodiments, based on the total mass of the first coating layer, the content of the mesoporous fibrous substances contained in the first coating layer is 10wt%-40wt%, the content of the mesoporous particles contained in the first coating layer is 10wt%-80wt%, and the content of the solid particles contained in the first coating layer is 0wt%-80wt%.

[0042] Controlling the content of the mesoporous fibrous substances, the mesoporous particles, and the solid particles in the first coating layer within the above range can obtain a separator with abundant pore structures and stable structures, effectively adsorb transition metal ions, and thus improve the cycle performance of the battery cell.

[0043] In some embodiments, the content of the mesoporous fibrous material in the second coating is 10wt%-40wt%, the content of the mesoporous particle in the second coating is 10wt%-80wt%, and the content of the solid particle in the second coating is 0wt%-80wt%, based on the total mass of the second coating.

[0044] Controlling the content of the mesoporous fibrous material, the mesoporous particle and the solid particle in the second coating within the above range is conducive to obtaining a second coating with a suitable mesoporous structure and high mechanical strength, and can effectively improve the lithium precipitation problem of the battery.

[0045] In some embodiments, the thickness of the base film is 3μm-10μm.

[0046] In some embodiments, the thickness of the first coating is 0.5μm-3μm.

[0047] In some embodiments, the thickness of the second coating is 0.5μm-1μm.

[0048] Controlling the thickness of each layer such as the first coating and the second coating in the separator is conducive to obtaining a separator with a suitable thickness, thereby helping to improve the energy density of the battery.

[0049] In some embodiments, the separator further comprises a bonding layer, which is arranged on at least a part of the surface of the first coating away from the base film.

[0050] The arrangement of the bonding layer enables the separator to have excellent bonding force with the electrode tab, so that the separator and the electrode tab are not prone to delamination during the use of the battery, which is conducive to improving the safety of the battery monomer.

[0051] In some embodiments, the separator satisfies at least one of the following characteristics (1)-(4):

[0052] (1) The porosity of the separator is 35%-50%;

[0053] (2) The wetting diffusion length of the separator is 30mm-100mm;

[0054] (3) The longitudinal tensile strength of the separator is 2000-5000kg / cm 2 ;

[0055] (4) The transverse tensile strength of the separator is 2500-6000kg / cm 2 .

[0056] When the separator satisfies any one or more characteristics, it is conducive to improving the cycle performance, energy density and safety of the battery monomer.

[0057] In a second aspect, the present application provides a lithium manganate battery monomer comprising a plurality of the battery monomers of the above embodiments.

[0058] In a third aspect, the present application provides a preparation method of a battery cell, comprising the following steps:

[0059] dispersing the mesoporous fibrous material and the mesoporous particulate in a solvent to obtain a material coating slurry;

[0060] coating the material coating slurry on at least one surface of a base film to form a material coating, thereby obtaining a separator;

[0061] assembling the separator with a positive electrode sheet and a negative electrode sheet to obtain a battery cell.

[0062] In a fourth aspect, the present application provides a battery device comprising a plurality of the battery cells of the above embodiments or a plurality of the lithium manganate battery cells of the above embodiments.

[0063] In a fifth aspect, the present application provides an energy storage device comprising a plurality of the battery cells of the above embodiments, a plurality of the lithium manganate battery cells of the above embodiments, or a plurality of the battery devices of the above embodiments.

[0064] In a sixth aspect, the present application provides an energy storage system comprising a power conversion device and the energy storage device of the above embodiments, wherein the power conversion device is configured to electrically connect a power generation device and the energy storage device.

[0065] In a seventh aspect, the present application provides an electric device comprising the battery cell of the above embodiments, the lithium manganate battery cell of the above embodiments, the battery device of the above embodiments, the energy storage device of the above embodiments, or the energy storage system of the above embodiments, wherein the battery cell or the battery device is configured to store or provide electric energy.

[0066] In an eighth aspect, the present application provides a charging network comprising a charging pile and the energy storage device of the above embodiments or the energy storage system of the above embodiments, wherein the energy storage device is configured to provide electric energy for the charging pile. BRIEF DESCRIPTION OF DRAWINGS

[0067] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The detailed description is made with reference to the accompanying drawings.

[0068] FIG. 1 is a schematic diagram of an embodiment of a separator provided by the present application;

[0069] FIG. 2 is a schematic diagram of another embodiment of a separator provided by the present application;

[0070] FIG. 3 is a schematic diagram of still another embodiment of a separator provided by the present application;

[0071] Fig. 4 is an exploded schematic view of a battery device according to an embodiment of the present application;

[0072] Fig. 5 is an exploded schematic view of a battery cell according to an embodiment of the present application;

[0073] Fig. 6 is a schematic view of an embodiment of a use device including a battery cell according to an embodiment of the present application as a power supply.

[0074] In the drawings: 100, battery device; 10, case, 11, first case, 12, second case; 20, battery cell assembly; 30, battery cell, 31, housing, 32, electrode assembly, 33, cover plate; 40, separator, 41, base film, 42, first coating layer, 43, adhesive layer, 44, second coating layer. DETAILED DESCRIPTION

[0075] The embodiments of the technical solutions of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0076] 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 belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application; the terms "comprising" and "having," and any variations thereof, as used in the specification and claims and the aforementioned drawings, are intended to cover not exclusive inclusions.

[0077] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0078] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative embodiments to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0079] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can mean that there are three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0080] In the description of the embodiments of the present application, the term "a plurality of" means two or more (including two), and similarly, "a plurality of groups" means two or more groups (including two groups), and "a plurality of pieces" means two or more pieces (including two pieces).

[0081] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "diameter", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the embodiments of the present application and simplifying the description, and does not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0082] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0083] In the present application, "at least one" means one or more, and "a plurality of" means two or more. "At least one of the following" or similar expressions means any combination of these items, including any combination of single item or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can mean a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0084] If not particularly specified, all steps of the present application can be performed in sequence or randomly, preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, it is mentioned that the method can further comprise step (c), which means that step (c) can be added to the method in any order. For example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0085] If not particularly specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0086] If not particularly specified, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0087] If not particularly specified, the following terms have the following meanings. Any undefined term has its commonly accepted meaning in the art.

[0088] In the embodiments of the present application, SEI is the abbreviation of "solid electrolyte interface", which refers to a solid electrolyte interface film with the characteristics of a solid electrolyte, i.e. a film formed by a passivation layer formed on the surface of the negative electrode material during the first charge and discharge process of the liquid lithium ion battery.

[0089] In the embodiments of the present application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging to continue to use.

[0090] The battery cell can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead-acid battery, etc. The present application is not limited thereto.

[0091] With the application and promotion of secondary batteries, people have higher and higher requirements for the energy density and service life of secondary batteries. However, in the process of charging and discharging of the secondary battery, the positive electrode material undergoes repeated redox reactions, and its crystal structure may change, leading to the dissolution of transition metal ions contained therein. When the transition metal ions in the positive electrode material are dissolved, a series of problems will be brought to the secondary battery. Specifically, the transition metal ions migrate in the electrolyte, reach the negative electrode and deposit on the surface of the negative electrode, which will destroy the solid electrolyte interface (SEI) film on the surface of the negative electrode, leading to the deterioration of the electrochemical performance of the negative electrode, such as increasing the internal resistance of the battery, reducing the capacity and cycle life of the battery, etc. At the same time, the dissolution of transition metal ions may also trigger a series of side reactions, such as catalyzing the decomposition of electrolyte, generating gas and unstable decomposition products, leading to rapid capacity decay of the battery and affecting the safety of the battery.

[0092] Based on the above background, the embodiments of the present application provide a battery monomer, by optimizing the separator and setting a material coating containing mesoporous fibrous and mesoporous particles in the separator, the separator can effectively absorb the transition metal ions dissolved in the positive electrode sheet, thereby effectively improving the cycle performance of the battery monomer.

[0093] Generally, the battery monomer includes a shell, and an electrode assembly and an electrolyte contained in the shell, the electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator, the separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly plays a role of preventing the positive electrode and the negative electrode from short circuiting, and can also make active ions pass through to form a loop.

[0094] Next, the positive electrode sheet, the negative electrode sheet, the separator and the electrolyte in the battery monomer are introduced in detail.

[0095] [Separator]

[0096] In some embodiments, the separator includes a base film and a material coating arranged on at least one surface of the base film, the material coating includes mesoporous fibrous substances and mesoporous particles, and at least part of the mesoporous particles are distributed between the mesoporous fibrous substances.

[0097] The term "mesoporous fibrous substance" refers to a one-dimensional material with an aspect ratio > 5, and the one-dimensional material has mesopores distributed therein. The mesopores can be distributed on the surface and inside the one-dimensional material. For example, on the surface, the mesopores can be distributed along the axial and lateral directions of the one-dimensional material. For example, inside the one-dimensional material, the mesopores can be uniformly or irregularly distributed. For example, the morphology of the fibrous substance can include at least one of rod-like, columnar, linear, tubular, rod-like and fibrous.

[0098] The term "mesoporous particle" refers to a zero-dimensional material with mesopores. For example, the morphology of the particle can include at least one of nanoflower, nanosphere, nanocube and nano-octahedron.

[0099] According to the definition of International Union of Pure and Applied Chemistry (IUPAC), the pore size in the range of 2 nm-50 nm is mesoporous.

[0100] The material coating including mesoporous fibrous and mesoporous particles arranged on at least one surface of the base film means that the separator contains abundant mesoporous structures with specific pore sizes. On the one hand, the mesoporous structures have a relatively high surface energy, which can effectively adsorb and capture transition metal ions dissolved from the positive electrode plate, hinder the migration of transition metal ions to the negative electrode plate or the electrolyte, not only make the SEI film on the surface of the negative electrode plate relatively stable, reduce the occurrence of side reactions in the battery cell, but also reduce the concentration fluctuation of transition metal ions in the electrolyte, thereby reducing the risk of electrolyte decomposition, which helps to prolong the cycle life of the battery and improve the capacity retention rate. On the other hand, the abundant mesoporous structures on the surface of the separator greatly increase the contact area between the separator and the electrolyte, improve the liquid retention capacity of the separator, and enhance the diffusion capacity of the electrolyte in the separator. This helps to supplement the electrolyte consumed on the electrode surface in time during the charging and discharging process of the battery cell, improves the stability of the active ion transmission channel, and also reduces the side reactions caused by insufficient electrolyte, thereby making the battery exhibit high cycle performance.

[0101] The mesoporous structure can also serve as an active ion transmission channel, allowing the electrolyte and active ions to pass through the separator at a faster speed, promoting the occurrence of electrochemical reactions in the battery cell, and reducing the polarization phenomenon in the battery cell. This helps to improve the charge and discharge capacity and cycle stability of the battery.

[0102] The plurality of mesoporous fibrous structures form a network structure by interlacing and overlapping each other. The network structure has a large number of pores, some of which are provided by the mesoporous fibrous structures, specifically the mesopores distributed in or on the mesoporous fibrous structures, and some of which are formed by the overlapping of the plurality of mesoporous fibrous structures. In this way, the network structure allows the surface of the separator to have a relatively uniform pore structure, which not only helps to adsorb transition metal ions, but also facilitates the infiltration of the electrolyte, thereby significantly improving the cycle performance of the battery cell.

[0103] The network structure also has a certain supporting effect, which is beneficial to improve the mechanical strength of the separator. At least part of the mesoporous particles is filled in the network structure, so that the mesoporous particles and the network structure form a nesting effect, thereby effectively improving the mechanical properties of the separator, making the separator not easy to be damaged during the use of the battery cell, and increasing the safety of the battery cell. In an embodiment, the other part of the mesoporous particles can be located on the surface of the network structure; it can also be located on the interface between the network structure and the base film.

[0104] In the embodiments of the present application, the material coating can be provided on both surfaces of the base film, or can be provided only on one surface of the base film.

[0105] In the embodiments of the present application, the material of the base film is not particularly limited, and any known porous structure diaphragm having good chemical stability and mechanical stability can be selected. For example, the base film can be selected from one of polyethylene, polypropylene and aromatic polyamide fiber.

[0106] In some embodiments, the thickness of the base film is 3 μm-10 μm. For example, the thickness of the base film can be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc.

[0107] In some embodiments, the length of the mesoporous fibrous material is 0.5 μm-5 μm. For example, the length of the mesoporous fibrous material can be 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, etc.

[0108] In some embodiments, the diameter of the mesoporous fibrous material is 50 nm-100 nm. For example, the diameter can be 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc.

[0109] In some embodiments, the aspect ratio of the mesoporous fibrous material is 10-100. For example, the aspect ratio of the mesoporous fibrous material can be 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, etc.

[0110] In some embodiments, the pore size of the mesoporous fibrous material is 5 nm-20 nm. For example, the pore size of the mesoporous fibrous material can be 5 nm, 8 nm, 10 nm, 12 nm, 15 nm, 18 nm, 20 nm, etc.

[0111] The length and diameter of the fibrous objects can be determined by the following method: cutting a 3.6 mm x 3.6 mm sample from an optional region of the separator, mapping the microstructure of the coating in the sample using a scanning electron microscope (e.g., ZEISS Sigma 300), selecting a high vacuum mode, a working voltage of 3 kV, and a magnification of 30,000x to obtain a SEM image; selecting multiple (e.g., 5 or more) test regions from the obtained SEM image to determine the length, each test region having a size of 0.5 pm x 0.5 pm, and then taking the average of the lengths obtained from each test region as the average length of the fibrous objects; and using the Nano Measurer particle size distribution statistical software to select multiple (e.g., 5 or more) test regions from the obtained SEM image to determine the diameter, each test region having a size of 0.5 pm x 0.5 pm, and then taking the average of the diameters obtained from each test region as the average diameter of the fibrous objects. Exemplarily, the length and diameter of the first mesoporous fibrous objects and the second mesoporous fibrous objects are determined by the above method.

[0112] Controlling the length, diameter, aspect ratio, and pore size of the mesoporous fibrous objects within the above ranges enables the plurality of mesoporous fibrous objects to be overlapped by interlacing with each other to form a network structure containing an appropriate amount of pore structure, which is beneficial for the packing of the mesoporous particles and forms a nesting effect, thereby effectively improving the adsorption capacity of the separator for transition metal ions and improving the mechanical properties of the separator, so that the battery cell exhibits high cycle performance and safety.

[0113] In some embodiments, the morphology of the mesoporous fibrous objects includes at least one of rod-like, columnar, linear, tubular, rod-like, and fibrous, and the material of the mesoporous fibrous objects includes at least one of silicon oxide, aluminum oxide, and magnesium oxide.

[0114] The mesoporous fibrous objects include at least one of mesoporous nanorods, mesoporous nanocolumns, mesoporous nanofibers, mesoporous nanowires, mesoporous nanobelts, mesoporous nanofilaments, and mesoporous nanotubes, and as examples, the mesoporous fibrous objects include, but are not limited to, at least one of mesoporous silicon oxide nanowires, mesoporous silicon oxide nanofibers, mesoporous silicon oxide nanotubes, mesoporous magnesium oxide nanorods, and mesoporous aluminum oxide nanowires.

[0115] The material with a suitable morphology is beneficial for the mesoporous fibrous objects to form a more stable network structure in the material coating, thereby effectively improving the mechanical properties and adsorption properties of the separator for transition metal ions, and thus improving the cycle life of the battery cell.

[0116] In some embodiments, the specific surface area of the mesoporous particles is 100-500 m 2 / g. Exemplarily, the specific surface area of the mesoporous particles can be 100 m 2 / g, 200 m2 / g, 300 m 2 / g, 400 m 2 / g, 500 m 2 / g, and the like typical but non-limiting values.

[0117] The specific surface area refers to the total area possessed by unit mass of a substance.

[0118] The specific surface area of the mesoporous particles is controlled within the above range, so that the mesoporous particles can be filled in the network structure in a relatively uniform morphology, and the packing between the mesoporous particles can be more stable and the packing density is higher, so that the mechanical properties of the separator are obviously improved.

[0119] In some embodiments, the mesoporous particles have a pore volume of 0.2-0.6 cm 3 / mg. For example, the mesoporous particles can have a pore volume of 0.2 cm 3 / mg, 0.3 cm 3 / mg, 0.4 cm 3 / mg, 0.5 cm 3 / mg, 0.6 cm 3 / mg, and the like typical but non-limiting values.

[0120] In the above, the pore volume refers to the pore volume, specifically the total volume of micropores, mesopores, macropores or porous structures per unit mass. In this application, the pore volume refers to the total volume of the mesopores of the first mesoporous particles, which can be measured by instruments and methods known in the art, and the principle can be low-temperature nitrogen adsorption and / or static capacity method. For example, GB / T+19587-2004 Gas Adsorption BET Method for Determining Specific Surface Area of Solid Substances can be referred to for convenient measurement by using a pore size analyzer. As an example, JW-BK122F is used for testing.

[0121] The pore volume of the mesoporous particles is controlled within the above range, so that the mesoporous particles can provide sufficient accommodation space to accommodate transition metal ions, thereby effectively improving the adsorption and capture of transition metal ions by the separator; the accommodation space can also store electrolyte, thereby improving the electrolyte wetting and retention properties of the separator, thereby effectively improving the cycle performance of the battery cell.

[0122] In some embodiments, the mesoporous particles have a particle size of 50 nm-500 nm. For example, the particle size can be 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, and the like typical but non-limiting values.

[0123] The mesoporous particles within the above particle size range enable the mesoporous particles to be sufficiently filled in the network structure, thereby effectively improving the mechanical properties of the separator.

[0124] In some embodiments, the mesoporous particles have a pore size of 5-20 nm. Exemplary, the pore size can be 5 nm, 8 nm, 10 nm, 12 nm, 15 nm, 18 nm, 20 nm, etc.

[0125] Controlling the pore size of the mesopores in the mesoporous particles within the above range enables the porous structure with specific channels to be distributed in the separator, which not only serves as a transport channel for active ions and electrolyte, enabling active ions and electrolyte to pass through the separator at a faster rate, improving the charge and discharge capacity of the battery cell, but also effectively adsorbs transition metal ions dissolved from the positive electrode sheet, thereby improving the cycle performance of the battery cell. The mesoporous structure can also serve as a transport channel for active ions, making the intercalation and deintercalation process of active ions more smooth and efficient, thereby reducing the possibility of lithium precipitation and improving the safety and cycle life of the battery.

[0126] In some embodiments, the mesoporous particles include at least one of mesoporous silicon oxide, mesoporous aluminum oxide, and mesoporous magnesium oxide.

[0127] The mesoporous particles have high chemical stability and inertness, which is more conducive to improving the safety of the battery cell.

[0128] In some embodiments, the surface of at least one of the mesoporous fibrous material and the mesoporous particle is connected with a chemical group, and the chemical group includes an amino group, a carboxyl group, and an ethylenediamine tetraethyl group.

[0129] By providing a chemical group with adsorption transition metal ion capability in the separator, the adsorption capacity of the separator for transition metal ions dissolved from the positive electrode sheet can be improved, reducing the occurrence of side reactions in the battery cell, thereby improving the cycle life of the battery cell.

[0130] In some embodiments, the material coating further includes solid particles, and the solid particles include at least one of silicon oxide, barium sulfate, boehmite, and montmorillonite.

[0131] The solid particles are further added in the material coating, and the solid particles and the mesoporous particles are mixed with each other, and at least part of the solid particles are filled in the network structure formed by the plurality of mesoporous fibrous materials. The presence of the solid particles not only can enhance the mechanical strength of the separator, making it less likely to be broken or deformed during the assembly and use of the battery cell, thereby improving the safety of the battery cell, but also can improve the overall pore structure of the separator, thereby being able to adjust the adsorption rate of the transition metal ions and the transport rate of the active ions and electrolyte, and improve the cycle performance of the battery cell.

[0132] The solid particles have high chemical stability and inertness, which is less likely to increase the safety risk of the battery cell.

[0133] In some embodiments, the Dv50 particle size of the solid particles is 0.3-0.5 μm. Exemplarily, the Dv50 particle size of the solid particles can be 0.3 μm, 0.4 μm, 0.5 μm, and the like typical but non-limiting values.

[0134] The "Dv50" refers to the particle size corresponding to the cumulative volume distribution percentage of 50% from the small particle size side in the particle size distribution of the particles.

[0135] Within the Dv50 particle size range, the solid particles and the mesoporous particles have a relatively high bulk density, and the solid particles are also beneficial to fill in the network structure formed by the plurality of mesoporous fibrous substances in a relatively uniform form, thus effectively improving the mechanical properties of the separator.

[0136] In some embodiments, the material coating further comprises a binder, and the binder comprises a water-soluble binder.

[0137] The addition of the binder in the material coating not only forms a firm bond between the material coating and the base film, preventing the material coating from falling off or peeling off, but also is beneficial to form a stable bond between the separator and the electrode plate.

[0138] The water-soluble binder has the advantages of good thermodynamic stability and environmental protection, thus being beneficial to the preparation and coating of the material coating slurry. As an example, the above-mentioned water-soluble binder can comprise at least one of water-soluble acrylic resin (for example, acrylic acid, methacrylic acid, sodium acrylate monomer homopolymer or copolymer with other comonomers), polyvinyl alcohol (PVA), isobutylene-maleic anhydride copolymer and polyacrylamide.

[0139] In some embodiments, the material coating comprises a first coating layer, and the first coating layer comprises the mesoporous fibrous substance and the mesoporous particles.

[0140] In some embodiments, the material coating can only comprise the first coating layer, and at this time, the positive electrode plate, the negative electrode plate and the separator can be in a wound structure, and the positive electrode plate, the negative electrode plate and the separator can also be in a laminated structure. In some other embodiments, the material coating can further comprise a coating layer.

[0141] The first coating layer can be arranged on both surfaces arranged in the thickness direction of the base film, or can be arranged on any one surface of the base film. As an example, the first coating layer is arranged on one surface of the base film. Please refer to FIG. 1, the separator 40 comprises the base film 41 and the first coating layer 42 arranged in a laminated manner, and the first coating layer 42 is arranged on one surface of the base film 41.

[0142] The material coating includes a first coating, i.e., the separator includes a base film and a first coating disposed on at least one surface of the base film. Due to the mesoporous fibrous material and mesoporous particles in the first coating, the positive electrode sheet can effectively adsorb transition metal ions dissolved from the positive electrode sheet, inhibit the occurrence of side reactions in the battery cell, and effectively improve the cycle life of the battery cell.

[0143] In some embodiments, the separator further includes a bonding layer, and the bonding layer is disposed on at least a portion of the surface of the first coating away from the base film.

[0144] The first coating can be disposed on both surfaces of the base film in the thickness direction, or can be disposed on any one surface of the base film. As an example, the first coating is disposed on one surface of the base film. Referring to FIG. 2, the separator 40 includes the base film 41, the first coating 42, and the bonding layer 43 stacked together, and the first coating 42 is located between the base film 41 and the bonding layer 43.

[0145] The separator includes a base film, a material coating, and a bonding layer stacked together, and the material coating only includes a first coating, i.e., the separator includes a base film, a first coating, and a bonding layer stacked together, and the first coating is disposed between the base film and the bonding layer.

[0146] The setting of the bonding layer not only prevents the first coating from falling off, but also enables the separator and the electrode sheet to have excellent bonding force, so that the separator and the electrode sheet are not prone to delamination during the use of the battery, which is beneficial to improve the safety of the battery cell.

[0147] In some embodiments, the thickness of the bonding layer is 0.5 μm-2 μm. As an example, the thickness of the bonding layer can be 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, and the like typical but non-limiting values.

[0148] Controlling the thickness of the bonding layer within the above range can fully exert its bonding capacity, and it is not easy to affect the adsorption and capture of transition metal ions by the mesoporous structure in the separator, and the bonding force between the separator and the electrode sheet is also good, so that the separator and the electrode sheet are not prone to separation during the charging and discharging process of the battery cell.

[0149] In the battery assembly of the winding structure, due to the different sizes of the corners of the electrode sheets in different turns at the corner area position, the corner area of the positive electrode sheet and the corner area of the negative electrode sheet do not completely correspond in size, and especially the convex surface of the negative corner area and the concave surface of the positive corner area are prone to lithium precipitation.

[0150] In some embodiments, the material coating includes a first coating and a second coating stacked together, and the second coating includes mesoporous fibrous material and mesoporous particles.

[0151] The positive electrode sheet, the negative electrode sheet, and the separator are in a wound structure, and the separator comprises a plurality of flat regions and a plurality of corner regions connected alternately, at least one corner region of the separator is provided with a second coating, and the second coating is arranged on the surface of the first coating away from the base film.

[0152] The first coating can be arranged on both surfaces arranged opposite in the thickness direction of the base film, or can be arranged on any one surface of the base film. As an example, the first coating is arranged on one surface of the base film. Referring to FIG. 3, the separator 40 comprises the base film 41, the first coating 42, and the second coating 44 stacked in layers, and the first coating 42 is located between the base film 41 and the second coating 44.

[0153] The material coating comprises a first coating and a second coating stacked in layers, that is, the separator comprises a base film, a first coating, and a second coating stacked in layers, and the first coating is located between the base film and the second coating.

[0154] The double-layer coating mode makes the surface of the separator not only have abundant mesoporous structures, but also helps to capture transition metal ions and improve the wettability of the separator to the electrolyte, which is conducive to improving the cycle performance of the battery cell and also conducive to improving the mechanical strength of the separator, so that the safety of the battery cell is effectively increased.

[0155] The second coating is arranged in the corner region of the separator, that is, the coating area of the second coating is located in the corner region of the separator, and the second coating contains second mesoporous fibrous structures and second mesoporous particles with mesoporous structures, which means that the corner region of the separator has sufficient mesoporous structures, which not only helps to provide a smooth active ion transmission channel, but also can improve the wettability of the separator to the electrolyte, especially the wettability of the corner region to the electrolyte, thereby reducing the problem of local active ion concentration being too high or too low and reducing the risk of lithium precipitation.

[0156] The plurality of mesoporous fibrous structures form a network structure by overlapping with each other, and at least part of the mesoporous particles are filled in the network structure, thereby increasing the mechanical properties of the corner region of the separator, reducing the extrusion and friction on the electrode sheet, helping to maintain the structural integrity of the electrode, building a good active ion transmission channel, and enabling ions to migrate more smoothly between the positive and negative electrodes, thereby improving the cycle life of the capacity of the battery cell.

[0157] In some embodiments, the first coating and the second coating each independently comprise at least one of a solid particle and a binder.

[0158] The solid particle can improve the mechanical properties of the first coating and the second coating, and the binder can improve the bonding force between the first coating, the second coating, and the base film, so that the separator is not easily damaged during the charging and discharging process of the battery cell.

[0159] In some embodiments, the first coating contains 10wt%-40wt% of mesoporous fibrous materials, based on the total mass of the first coating. Exemplarily, the content of mesoporous fibrous materials can be 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, and the like typical but non-limiting values.

[0160] Controlling the mass content of mesoporous fibrous materials within the above range means that the first coating contains an appropriate amount of mesoporous fibrous materials, so that the plurality of mesoporous fibrous materials can be overlapped with each other to form a network structure, thereby effectively improving the mechanical properties of the separator.

[0161] In some embodiments, the first coating contains 10wt%-80wt% of mesoporous particles, based on the total mass of the first coating. Exemplarily, the content of mesoporous particles can be 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, and the like typical but non-limiting values.

[0162] Controlling the content of mesoporous particles within the above range allows the separator not only to have abundant mesoporous structures, but also to effectively improve the mechanical properties of the separator.

[0163] In some embodiments, the first coating contains 0wt%-80wt% of solid particles, based on the total mass of the first coating. Exemplarily, the content of solid particles can be 0, 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, and the like typical but non-limiting values.

[0164] Controlling the mass content of solid particles within the above range allows the solid particles to play a supporting role, thereby effectively improving the mechanical properties of the separator.

[0165] In some embodiments, the first coating contains 0.3wt%-1wt% of binder, based on the total mass of the first coating. Exemplarily, the content of binder can be 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1.0wt%, and the like typical but non-limiting values.

[0166] The network structure in the first coating can form a stable nested structure with mesoporous particles, solid particles, and the like, thereby allowing the separator to maintain high adhesion at the above-mentioned usage.

[0167] In some embodiments, the second coating contains 10wt%-40wt% of mesoporous fibrous materials, based on the total mass of the second coating. Exemplarily, the content of mesoporous fibrous materials can be 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, and the like typical but non-limiting values.

[0168] In some embodiments, the second coating contains 10wt%-80wt% of mesoporous particles, based on the total mass of the second coating. Exemplarily, the content of mesoporous particles can be 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, and the like typical but non-limiting values.

[0169] In some embodiments, the second coating contains 0wt%-80wt% of solid particles, based on the total mass of the second coating. Exemplarily, the content of solid particles can be 0, 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, and the like typical but non-limiting values.

[0170] Controlling the content of mesoporous fibrous materials, mesoporous particles and solid particles in the second coating within the above range is conducive to obtaining a second coating with appropriate pore structure and high mechanical strength, thereby enhancing the wettability and retention capacity of the separator for electrolyte, and reducing the problem of excessively high or low local active ion concentration and the risk of lithium precipitation.

[0171] In some embodiments, the thickness of the first coating is 0.5μm-3μm. Exemplarily, the thickness of the first coating can be 0.5μm, 1μm, 2μm, 3μm, and the like typical but non-limiting values.

[0172] Controlling the thickness of the first coating within the above range not only endows the separator with adsorption performance for transition metal ions, but also improves the wettability and retention capacity of the separator for electrolyte, and improves the mechanical properties of the separator.

[0173] In some embodiments, the thickness of the second coating is 0.5μm-1μm. Exemplarily, the thickness of the second coating can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, and the like typical but non-limiting values.

[0174] Controlling the thickness of the second coating within the above range enables the electrode assembly in a wound structure to have high wettability and liquid retention capacity for electrolyte, so that the corner region in the electrode assembly has sufficient supply of electrolyte, avoiding the problem of lithium precipitation caused by electrolyte dryness.

[0175] In some embodiments, the porosity of the separator is 35-50%. Exemplarily, the porosity of the separator can be 35%, 38%, 40%, 42%, 45%, 48%, 50%, etc.

[0176] The porosity refers to the ratio of the volume of pores in the separator to the total volume of the separator, usually expressed in percentage, and can be measured by methods known in the art.

[0177] The porosity of the separator can reflect the relative size of the internal void space of the separator. On the one hand, the pores can be used to adsorb transition metal ions dissolved from the positive electrode sheet, reduce the occurrence of side reactions in the battery, thereby improving the cycle performance of the battery monomer. On the other hand, it can provide a storage and transmission channel for the electrolyte, improve the conduction efficiency of active ions, reduce the internal resistance of the battery monomer, and improve the charge and discharge capacity of the battery monomer.

[0178] In some embodiments, the wettability diffusion length of the separator is 30-100 mm. Exemplarily, the wettability diffusion length of the separator can be 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, etc. typical but non-limiting values.

[0179] The separator has good wettability and retention properties for the electrolyte, thereby improving the ion conductivity of the separator and the capacity performance of the secondary battery.

[0180] The wetting length of the separator has the meaning known in the art and can be measured by methods known in the art. Exemplary test method: cut the separator into a sample with a diameter of 5 mm and a length of 100 mm, fix both ends of the sample and place it horizontally; take 0.5 mg of electrolyte and drop it in the center of the sample, after a specified time (1 min in this application), take a photo and measure the length of the electrolyte diffusion, thereby obtaining the wetting length and wetting speed of the separator. For accuracy, multiple (e.g. 5 to 10) samples can be tested, and the test results are obtained by calculating the average value. The electrolyte can be prepared as follows: mix ethylene carbonate (EC), methyl ethyl carbonate (EMC) and diethyl carbonate (DEC) in a mass ratio of 30:50:20 to obtain an organic solvent, and dissolve LiPF6 which is sufficiently dried in the above organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0181] In some embodiments, the longitudinal tensile strength of the separator is 2000-5000 kg / cm 2 .

[0182] In some embodiments, the transverse tensile strength of the separator is 2500-6000 kg / cm 2 .

[0183] The separator has high tensile strength in both the transverse and longitudinal directions, so that the separator is not easily damaged during charging and discharging of the battery, thereby improving the safety and reliability of the battery cell.

[0184] The tensile strength of the separator has the meaning known in the art and can be measured using methods known in the art. For example, the test can be performed in accordance with the standard GB / T 36363-2018.

[0185] [Positive electrode tab]

[0186] The positive electrode tab includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.

[0187] As an example, the positive electrode current collector has two surfaces opposite in the thickness direction thereof, and the positive electrode film layer is disposed on either one or both of the two opposite surfaces of the positive electrode current collector.

[0188] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, an aluminum foil can be used. The composite current collector can include a polymer material base film and a metal layer formed on at least one surface of the polymer material base film. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0189] In some embodiments, when the battery cell is a lithium ion battery, the positive electrode active material can use a positive electrode active material known in the art for lithium ion batteries. As an example, the positive electrode active material can include at least one of a lithium-containing phosphate of olivine structure, a lithium transition metal oxide, and a modified compound of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material can also be used. These positive electrode active materials can be used alone only one or in combination of two or more. Among them, examples of the lithium transition metal oxide can include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3Mn 1 / 3 O2 (which can also be referred to as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be referred to as NCM523), LiNi0.5 Co 0.25 Mn 0.25 O2(also can be referred to as NCM 111), LiNi 0.6 Co 0.2 Mn 0.2 O2(also can be referred to as NCM 622), LiNi 0.8 Co 0.1 Mn 0.1 O2(also can be referred to as NCM 811), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and modified compounds thereof. Examples of lithium-containing olivine-structured phosphates can include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite of lithium manganese iron phosphate and carbon.

[0190] In some embodiments, when the battery cell of the present application is a sodium-ion battery, the positive active material can employ positive active materials known in the art for sodium-ion batteries. As an example, the positive active material can include, but is not limited to, at least one of sodium-containing transition metal oxides, polyanion materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), Prussian blue-type materials.

[0191] In some embodiments, the positive electrode film layer can further optionally include a binder. As an example, the binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0192] In some embodiments, the positive electrode film layer can further optionally include a conductive agent. As an example, the conductive agent can include at least one of super P carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0193] In some embodiments, the positive electrode tab can be prepared by dispersing the above-mentioned components for preparing the positive electrode tab, such as the positive active material, the conductive agent, the binder, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on a positive electrode current collector, and after processes such as drying, cold pressing, etc., the positive electrode tab can be obtained.

[0194] [Negative electrode tab]

[0195] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0196] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0197] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, a copper foil can be used. The composite current collector can include a polymer material-based film and a metal layer formed on at least one surface of the polymer material-based film. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material-based film such as a film based on polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc. In some embodiments, the negative electrode active material can be a negative electrode active material known in the art for use in a battery.

[0198] As an example, the negative electrode active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, etc. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative electrode active material for a battery can also be used. The negative electrode active material can be used alone or in combination of two or more.

[0199] In some embodiments, the negative electrode film layer can further include a binder. The binder can be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0200] In some embodiments, the negative electrode film layer can further include a conductive agent. The conductive agent can be selected from at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0201] In some embodiments, the negative electrode film layer can further include other auxiliary agents, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0202] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-described components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry, coating the negative electrode slurry on the negative electrode current collector, and drying, cold-pressing, etc. to obtain the negative electrode sheet.

[0203] [Electrolyte]

[0204] The electrolyte plays a role of conducting ions between the positive electrode tab and the negative electrode tab. The type of the electrolyte is not specifically limited in the present application, and can be selected as needed.

[0205] The type of the electrolyte is not specifically limited in the present application, and can be selected as needed. For example, the electrolyte can be in a liquid state, a gel state, or a full solid state.

[0206] In some embodiments, the electrolyte described above adopts an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0207] In some embodiments, when the battery cell is a lithium ion battery, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoroboric oxalate, lithium difluoroboric bisoxalate, lithium difluorophosphoric bisoxalate, and lithium tetrafluorophosphoric oxalate.

[0208] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclobutane sulfone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0209] In some embodiments, the electrolyte solution described above can also optionally include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can also include an additive capable of improving certain performance of the battery, such as an additive capable of improving overcharge performance of the battery, an additive capable of improving high-temperature or low-temperature performance of the battery, etc.

[0210] In a second aspect, the embodiments of the present application provide a lithium manganate battery cell, including a plurality of the battery cells described above.

[0211] The lithium manganate battery cell uses lithium manganate as a positive electrode active material, and has many advantages. For example, lithium manganate has a high ion diffusion rate, which can improve the rate performance of the battery cell. For example, lithium manganate has a low cost, which is very beneficial for large-scale application and reduction of battery cost. For example, lithium manganate can withstand a large current for charging and discharging, and has good high-current charging and discharging performance. However, the manganese element contained in lithium manganate is easily dissolved out during the charging and discharging of the battery, which causes the capacity of the lithium manganate battery cell to decay quickly and the cycle life to be short.

[0212] Therefore, by optimizing the separator in the lithium manganate battery monomer, the transition metal ions dissolved from the positive electrode sheet can be effectively captured, hindering the migration of the transition metal ions to the negative electrode sheet or the electrolyte, thereby effectively inhibiting the occurrence of side reactions inside the battery monomer, which enables the battery to maintain a high capacity after multiple charge and discharge cycles, thereby prolonging the cycle life of the lithium manganate battery monomer. On the other hand, the rich mesoporous structure on the surface of the separator greatly increases the contact area between the separator and the electrolyte, improves the liquid retention capacity of the separator, and enhances the diffusion performance of the electrolyte in the separator. This helps to supplement the electrolyte consumed on the electrode surface in a timely manner during the charge and discharge process of the lithium manganate battery monomer, thereby reducing side reactions caused by insufficient electrolyte, and thus enabling the lithium manganate battery to exhibit high cycle performance.

[0213] The third aspect of the embodiments of the present application provides a preparation method of a battery monomer, comprising the following steps:

[0214] Step S10, dispersing the mesoporous fibrous material and the mesoporous particles in a solvent to obtain a material coating slurry;

[0215] Step S20, coating the coating slurry on at least one surface of the base film to form a material coating layer, thereby obtaining a separator;

[0216] Step S30, assembling the separator with a positive electrode sheet and a negative electrode sheet to obtain a battery monomer.

[0217] The preparation method of the battery monomer provided by the embodiments of the present application coats the slurry containing the mesoporous fibrous material and the mesoporous particles on the surface of the base film to form a separator containing a material coating layer, and then assembles the obtained separator with a positive electrode sheet and a negative electrode sheet, thereby effectively preparing a battery monomer with the performance as described in the above embodiments. In addition, the preparation method of the battery monomer is simple, reliable and controllable, and is conducive to wide application.

[0218] In some embodiments, in step S10, the mesoporous fibrous material and the mesoporous particles are selected as described above, which will not be repeated here.

[0219] In some embodiments, in step S10, the material coating slurry can further include other components, for example, it can further include a dispersant, a wetting agent, a binder, and a solid particle. For example, the material coating slurry further includes a dispersant sodium carboxymethyl cellulose. For example, the binder is selected as described above, which will not be repeated here. For example, the solid particle is selected as described above, which will not be repeated here.

[0220] In some embodiments, in step S10, the solvent used for preparing the material coating slurry can be water, for example, deionized water.

[0221] In some embodiments, the solid content of the material coating slurry in step S10 is 20-45%.

[0222] In some embodiments, the selection of the base film in step S20 is as described above, which will not be repeated here.

[0223] In some embodiments, a coating machine can be used when applying the material coating slurry in step S20. The present application does not have special restrictions on the model of the coating machine, for example, a commercially available coating machine can be used. The coating machine includes a gravure roll, which is used to transfer the first coating slurry to the base film.

[0224] In some embodiments, the material coating slurry can be applied by transfer coating, rotary spraying, dip coating, etc. in step S20.

[0225] In some embodiments, the material coating only includes the first coating, so that after the material coating slurry is applied in step S20, the first coating is formed on at least one surface of the base film, and the dried separator is obtained. The drying conditions include a temperature of 75-85°C and a wind speed frequency of 20-60Hz.

[0226] In some embodiments, the separator not only includes the material coating, but also includes a bonding layer. Therefore, after the material coating slurry is applied and dried in step S20, the following step is included: applying a bonding slurry containing a bonding agent to at least a part of the surface of the first coating, and forming a bonding layer after drying.

[0227] Specifically, the drying conditions for forming the bonding layer include a temperature of 75-85°C and a wind speed frequency of 30-60Hz.

[0228] Specifically, the bonding slurry can be an organic system. As an example, at least one material of a monomer copolymer or a homopolymer of polyvinylidene fluoride and polytetrafluoroethylene is dispersed in an organic solvent to form an organic bonding slurry, wherein the organic solvent includes at least one of acetone, N-methyl pyrrolidone, and dimethyl carbonate.

[0229] Specifically, the bonding slurry can be an aqueous system. As an example, a water-soluble bonding agent is dispersed in water to form an aqueous bonding slurry. The above-mentioned water-soluble bonding agent can include at least one of a water-soluble acrylic resin (for example, a sodium monomer homopolymer of acrylic acid, methacrylic acid, acrylic acid, or a copolymer with other comonomers), polyvinyl alcohol (PVA), isobutylene-maleic anhydride copolymer, and polyacrylamide.

[0230] In some embodiments, the material coating only includes the first coating layer and the second coating layer, and thus, after the first coating layer is coated and dried, the second coating layer containing the mesoporous fibrous material and the mesoporous particles is coated on part of the surface of the first coating layer in step S20, and dried to obtain the second coating layer.

[0231] The coating area of the second coating layer is located at the corner area of the separator. When the electrode assembly is in a wound structure, the coating area of the second coating layer can be set to a fixed width by spraying according to the circumference of the winding needle when the electrode assembly is wound, so as to ensure that the coating area of the second coating layer corresponds to the corner area of the separator when the electrode assembly is wound.

[0232] Specifically, the second coating layer slurry further includes second solid particles. The selection of the second solid particles is as described above and will not be repeated here.

[0233] Specifically, the solvent used for preparing the second coating layer slurry can be water, for example, deionized water.

[0234] In some embodiments, the electrode assembly and the electrolyte can be assembled to form a battery cell in step S30. The electrode assembly includes a negative electrode sheet, a separator, and a positive electrode sheet.

[0235] For example, the negative electrode sheet, the separator, and the positive electrode sheet can be wound or stacked to form an electrode assembly. The electrode assembly is placed in an outer package, and after drying, the electrolyte is injected. After vacuum packaging, standing, formation, shaping, and other processes, a battery cell is obtained. The shape of the battery cell is not particularly limited, and it can be cylindrical, square, or any other shape.

[0236] The fourth aspect of the embodiments of the present application provides a battery device including a plurality of battery cells or a plurality of lithium manganate battery cells according to the above embodiments.

[0237] The battery device mentioned in the embodiments of the present application can include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly can include a plurality of battery cells connected in series, in parallel, or in a mixed connection through a busbar component.

[0238] In some embodiments, the battery cell assembly is usually formed by arranging a plurality of battery cells.

[0239] For example, the battery cell assembly can be a battery module formed by arranging and fixing a plurality of battery cells into an independent module. For example, the battery module can be formed by bundling a plurality of battery cells with a cable tie.

[0240] In some embodiments, the battery device can be a battery pack including a box body and one or more battery cell assemblies, and the battery cell assemblies are accommodated in the box body.

[0241] As an example, the battery cell assembly can be a battery module. The battery cell assembly can be housed in the box by fixing the battery module in the box.

[0242] As an example, the battery cell assembly can also be housed in the box by fixing a plurality of battery cells directly in the box.

[0243] As an example, the box can include a first box and a second box. The first box and the second box are fastened so that an enclosed space is formed inside the box to accommodate the battery cell assembly. The enclosed here means covered or closed, which can be sealed or unsealed. The first box can be a top cover or a bottom plate.

[0244] As an example, the box can include a top cover, a frame and a bottom plate. The top cover and the bottom plate are connected with the frame respectively, so that an enclosed space is formed inside the box to accommodate the battery cell assembly.

[0245] In some embodiments, the box can be part of the chassis structure of the vehicle. For example, part of the box can be at least part of the floor of the vehicle, or part of the box can be at least part of the cross beam and the longitudinal beam of the vehicle.

[0246] The fifth aspect of the embodiments of the present application is an energy storage device, which includes a plurality of battery cells of the above embodiments, a plurality of lithium manganate battery cells of the above embodiments or a plurality of battery devices of the above embodiments. The battery cells or the battery devices are used to store or provide electric energy.

[0247] The energy storage device mentioned in the embodiments of the present application includes one or more battery clusters to improve the voltage and capacity of the energy storage device. The battery cluster can include a plurality of battery devices, and the plurality of battery devices are connected in series through the busbar component to improve the voltage of the energy storage device. When the energy storage device includes a plurality of battery clusters, the plurality of battery clusters are connected in parallel to improve the capacity of the energy storage device.

[0248] The energy storage device can be used in energy storage power stations, wind power systems, solar power systems, mobile power systems or temporary power supply systems, etc. The energy storage device can store electric energy as needed and output electric energy at appropriate times. For example, the energy storage device can store electric energy during the low electricity consumption period, and provide electric energy for related users or electric equipment during the peak electricity consumption period.

[0249] In some embodiments, the energy storage device is an energy storage container or an energy storage cabinet.

[0250] In some embodiments, the energy storage device can include a cabinet body and one or more battery clusters, and the battery clusters are housed in the cabinet body.

[0251] In some embodiments, the energy storage device can include a thermal management module, a master control module, a general control module, a power distribution module and a fire-fighting module, etc.

[0252] As an example, the thermal management module can include a liquid cooling unit, which provides cooling liquid to each battery device through a pipeline for adjusting the temperature of the battery cell.

[0253] As an example, the master control module can serve as a battery management unit of the battery cluster for monitoring and managing the battery cluster. The master control module can monitor information such as current, voltage, power, or temperature of the battery cluster. For example, the charging and discharging current, voltage, etc. of the battery cluster can be controlled. The master control module includes an auxiliary battery management unit, a fusion switch, and the like.

[0254] As an example, the master control module can serve as a battery management unit of the battery cluster for monitoring and managing the battery cluster. The master control module can monitor information such as current, voltage, power, or temperature of the battery cluster. For example, the charging and discharging current, voltage, etc. of the battery cluster can be controlled. The master control module includes an auxiliary battery management unit, a fusion switch, and the like.

[0255] As an example, the fire control module includes a control panel, a detector, an alarm device, and the like, for detecting, alarming, or extinguishing the energy storage system.

[0256] As an example, the power distribution module can be used to distribute power to the energy storage device power module.

[0257] The sixth aspect of the embodiments of the present application provides an energy storage system, which includes a power conversion device and the energy storage device of the above-mentioned embodiments. The power conversion device is used to electrically connect the power generation device and the energy storage device.

[0258] In some embodiments, the energy storage system can include one or more energy storage devices and a power conversion device, which is used to connect between the power generation device and the energy storage device. The power generation device is used to generate electric energy, and the electric energy generated by the power generation device can be stored in the energy storage device through the power conversion device. As an example, the power generation device can be a solar panel, a water power generation device, a fire power generation device, a wind power generation device, and the like. The specific type of the power generation device is not limited in the present application.

[0259] The seventh aspect of the embodiments of the present application provides a power consumption device, which includes the battery cell of the above-mentioned embodiments, the lithium manganate battery cell of the above-mentioned embodiments, the battery device of the above-mentioned embodiments, the energy storage device of the above-mentioned embodiments, or the energy storage system of the above-mentioned embodiments. The battery cell or the battery device is used to store or provide electric energy.

[0260] The technical solutions described in the embodiments of the present application are applicable to various battery cell using electric devices, for example, mobile phones, portable devices, notebook computers, electric vehicles, electric toys, electric tools, vehicles, ships and spacecraft, for example, spacecraft including airplanes, rockets, space shuttles and spaceships.

[0261] The eighth aspect of the embodiments of the present application provides a charging network, comprising a charging pile and the energy storage device of the above embodiments or the energy storage system of the above embodiments, and the energy storage device is used to provide electric energy for the charging pile.

[0262] In the above embodiments, the charging pile is electrically connected with the energy storage device, and the energy storage device is used to provide electric energy for the charging pile. The battery device in the charging pile and the energy storage device are electrically connected through a cable, and the battery device can provide the stored electric energy to the charging pile. The charging pile has one or more connectors for connecting with electric equipment (such as a vehicle), so as to supplement the electric energy to the electric equipment.

[0263] The energy storage device can be located inside the charging pile (such as a charging and storage integrated machine) or outside the charging pile.

[0264] The battery cell, the battery device and the electric device provided by the embodiments of the present application are described below with reference to the accompanying drawings.

[0265] FIG. 4 is an exploded view of the battery device 100 as an example. The battery device 100 comprises a box 10 and a battery cell assembly 20, and the battery cell assembly 20 is accommodated in the box 10. Wherein, the box 10 is used to provide an accommodation space for the battery cell assembly 20, and the box 10 can adopt various structures. In some embodiments, the box 10 can comprise a first box 11 and a second box 12, and the first box 11 and the second box 12 are overlapped with each other, and the first box 11 and the second box 12 jointly define an enclosed space for accommodating the battery cell assembly 20. Of course, the box 10 formed by the first box 11 and the second box 12 can have various shapes, such as a cylinder, a cuboid, etc. A plurality of battery cell assemblies 20 can be arranged in the battery box in any manner.

[0266] In the battery device 100, the battery cell assembly 20 can be one or more, and the plurality of battery cell assemblies 20 can be connected in series, in parallel or in a mixed manner. The mixed connection means that the plurality of battery cell assemblies 20 are connected in series and in parallel. The plurality of battery cell assemblies 20 can be directly connected in series, in parallel or in a mixed manner, and then the whole of the plurality of battery cell assemblies 20 is accommodated in the box 10; of course, the battery device 100 can also be that the plurality of battery cell assemblies 20 are first connected in series, in parallel or in a mixed manner to form a battery module, such as a battery module, a battery pack, etc., and then the plurality of battery modules are connected in series, in parallel or in a mixed manner to form a whole, and the whole is accommodated in the box 10.

[0267] The battery cell assembly 20 includes a plurality of battery cells 30, and FIG. 5 is an exploded view of the battery cell 30 as an example. The battery cell 30 includes a case 31, a cover plate 33, an electrode assembly 32, and other functional components.

[0268] The case 31 can include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity. The case 31 is a hollow structure having an open end, and the case 31 is configured to fit the cover plate 33 to form an internal environment that accommodates the electrode assembly 32, an electrolyte, and other functional components. The case 31 can be various shapes and sizes, such as a cuboid, a cylinder, a hexagonal prism, etc. Specifically, the shape of the case 31 can be determined according to the specific shape and size of the electrode assembly 32. The material of the case 31 can be, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which are not limited herein. The cover plate 33 refers to a component that covers the opening of the case 31 to isolate the internal environment of the battery cell 30 from the external environment. The material of the cover plate 33 can be, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which are not limited herein.

[0269] FIG. 6 is a schematic view of an electrical device as an example. The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the demand of the electrical device for high power and high energy density, a battery pack or a battery module can be used.

[0270] Embodiment

[0271] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are for the purpose of explanation of the present application, and should not be understood as a limitation of the present application. In the embodiments, the specific techniques or conditions not mentioned are performed according to the techniques or conditions described in the literature in the art or according to the product manual. The reagents or instruments not mentioned the manufacturer are all conventional products that can be commercially available.

[0272] Embodiment 1

[0273] The present embodiment provides a battery cell.

[0274] [Separator]

[0275] The diaphragm comprises a base film (polypropylene / 3 μm) and a first coating layer arranged on both surfaces of the base film, the first coating layer comprising a mass ratio of 20:80 mesoporous fibrous (mesoporous silica nanowire) and mesoporous particles (mesoporous aluminum oxide), a plurality of mesoporous fibrous structures interlaced to form a network structure, and at least part of the mesoporous particles filled in the network structure. The length of the mesoporous fibrous structure is 2.5 μm, the diameter is 50 nm, the aspect ratio is 50, and the pore size is 10 nm; the particle size of the mesoporous particles is 50 nm, the pore size is 10 nm, and the thickness of the diaphragm is 5 μm.

[0276] The preparation method of the diaphragm comprises the following steps:

[0277] The mesoporous fibrous structure and the mesoporous particles are mixed in a mass ratio of 20:80, dispersed in water, stirred for 1 h to obtain a first coating layer slurry; the first coating layer slurry is coated on the two surfaces of the base film, and is dried at a temperature of 80°C and a wind frequency of 40 Hz to form a first coating layer with a thickness of 1 μm on the surface of the base film, thereby obtaining the diaphragm.

[0278] [Preparation of positive electrode sheet]

[0279] The positive active material (lithium manganate), the conductive agent (carbon nanotube) and the binder PVDF are dispersed into N-methyl pyrrolidone (NMP) in a weight ratio of 100:2:2, and are uniformly mixed by stirring to form a uniform positive electrode slurry; the positive electrode slurry is coated on the two surfaces of the positive electrode current collector aluminum foil, and is then dried in an oven at 90°C, and is subjected to rolling treatment, and is cut to obtain the positive electrode sheet.

[0280] [Preparation of negative electrode sheet]

[0281] The artificial graphite, the conductive carbon black, the binder carboxymethyl cellulose (CMC) and the solvent water are uniformly mixed in a weight ratio of 95:2:3:100 to obtain a negative electrode slurry; the negative electrode slurry is uniformly coated on the two surfaces of the negative electrode current collector copper foil, and is dried, cold-pressed and cut to obtain the negative electrode sheet.

[0282] [Preparation of electrolyte]

[0283] In an argon-filled glove box (water content <10 ppm, oxygen content <1 ppm), ethylene carbonate, diethyl carbonate and dimethyl carbonate are mixed in a volume ratio of 1:1:1, and then LiPF6 is dissolved in the above solution to obtain an electrolyte. In the electrolyte, the concentration of LiPF6 is 1 mol / L.

[0284] [Preparation of battery cell]

[0285] The positive electrode sheet, the negative electrode sheet and the separator are arranged in the order of positive electrode-separator-negative electrode, one end of the positive electrode sheet, the negative electrode sheet and the two separators is fixed on the discharge roller, and the other end is fixed on the winding shaft after being stacked together. The winding shaft is rotated by using a motor to wind the positive electrode sheet, the negative electrode sheet and the two separators to obtain a wound cell. Subsequently, the obtained cell is placed in an aluminum plastic film, electrolyte is injected, and the cell is subjected to vacuum packaging, aging, formation (0.1C charging to 4.6V), second sealing, capacity sorting processes to complete the preparation of the battery monomer.

[0286] Examples 2-19

[0287] Examples 2-19 provide a battery monomer, wherein the main difference between the battery monomer and Example 1 is that the separator sheet is different, specifically at least one of the following is different: the specification of the mesoporous fibrous material in the first coating layer, such as aspect ratio, particle size, particle size of mesoporous particles, content of binder, thickness of the first coating layer, thickness of the adhesive layer, and the specification of the mesoporous fibrous material in the second coating layer, such as aspect ratio, particle size, particle size of mesoporous particles, thickness of the second coating layer. For details, see Tables 1 and 2.

[0288] Table 1

[0289] In Table 1:

[0290] W1 represents the mass content of the mesoporous fibrous material in the first coating layer, with units of wt%; W2 represents the mass content of the mesoporous particles in the first coating layer, with units of wt%; W3 represents the mass content of the solid particles in the first coating layer, with units of wt%; W4 represents the mass content of the binder in the first coating layer, with units of wt%.

[0291] L1 / D1 represents the aspect ratio of the mesoporous fibrous material in the first coating layer; L1 represents the length of the mesoporous fibrous material in the first coating layer, with units of μm; D1 represents the diameter of the mesoporous fibrous material in the first coating layer, with units of nm; d1 represents the pore size of the pores contained in the mesoporous fibrous material in the first coating layer, with units of nm; d2 represents the pore size of the pores contained in the mesoporous particles in the first coating layer, with units of nm; d3 represents the particle size of the solid particles in the first coating layer, with units of μm.

[0292] H1 represents the thickness of the first coating layer, with units of μm; H2 represents the thickness of the adhesive layer, with units of μm; X1 represents the adsorption site.

[0293] The solid particles contained in the first coating layer are boehmite.

[0294] Table 2

[0295] In Table 2:

[0296] P1 represents the mass content of the mesoporous fibrous material in the second coating layer, in wt%; P2 represents the mass content of the mesoporous particle in the second coating layer, in wt%; P3 represents the mass content of the solid particle in the second coating layer, in wt%.

[0297] L2 / D2 represents the length-diameter ratio of the mesoporous fibrous material in the second coating layer; L2 represents the length of the mesoporous fibrous material in the second coating layer, in μm; D2 represents the diameter of the mesoporous fibrous material in the second coating layer, in nm; d4 represents the pore diameter of the pores contained in the mesoporous fibrous material in the second coating layer, in nm; d5 represents the pore diameter of the pores contained in the mesoporous particle in the second coating layer, in nm.

[0298] H3 represents the thickness of the first coating layer, in μm; X2 represents the adsorption site.

[0299] A represents that the raw materials and their specifications in the first coating layer are consistent with those in the first coating layer in Example 4.

[0300] The mesoporous fibrous material contained in the second coating layer is mesoporous silica nanowire; the mesoporous particle contained in the second coating layer is mesoporous alumina, and the particle size thereof is 50 nm; the solid particle contained in the second coating layer is boehmite, and the particle size thereof is 0.5 μm.

[0301] Comparative Example 1

[0302] This comparative example provides a separator, which is different from Example 4 in that the first mesoporous particle is replaced by the first solid particle, i.e., the separator comprises a base film and a first coating layer disposed on both surfaces of the base film, and the first coating layer comprises mesoporous fibrous material, solid particle and binder at a mass ratio of 20:79.5:0.5.

[0303] Comparative Example 2

[0304] This comparative example provides a separator, which is different from Example 4 in that the mesoporous fibrous material is replaced by the solid particle, and the mesoporous particle is replaced by the solid particle, i.e., the separator comprises a base film and a first coating layer disposed on both surfaces of the base film, and the first coating layer comprises solid particle and binder at a mass ratio of 99.5:0.5.

[0305] Performance Test

[0306] (1) Tensile strength test

[0307] The transverse tensile strength and the longitudinal tensile strength are tested according to GB / T 1040.3-2006, respectively.

[0308] (2) Infiltration diffusion length

[0309] The test process of the infiltration diffusion length of the electrolyte is as follows:

[0310] The separator is cut into a sample with a diameter of 5 mm and a length of 100 mm, and the sample is fixed at both ends and placed horizontally; 0.5 mg of electrolyte is dropped in the center of the sample, and after a specified time (1 min in this application), a photograph is taken and the length of the electrolyte diffusion is measured, thereby obtaining the wetting length and wetting speed of the separator. For accuracy, 5 samples can be tested, and the test results are obtained by calculating the average value. The electrolyte can be prepared as follows: ethylene carbonate (EC), methyl ethyl carbonate (EMC) and diethyl carbonate (DEC) are mixed in a mass ratio of 30:50:20 to obtain an organic solvent, and LiPF6 that is fully dried is dissolved in the above organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0311] (3) Mn dissolution amount test

[0312] The content of manganese element has the meaning known in the art, which can be tested by a method known in the art. The content of the target element can be determined according to EPA6010D-2014 Inductively Coupled Plasma Atomic Emission Spectrometry, using an ICAP-7000 inductively coupled plasma emission spectrometer (ICP-OES) of Thermo Fisher Scientific.

[0313] The specific test method is as follows:

[0314] The material peeling off the surface of the negative electrode sheet is used as the sample to be tested.

[0315] 0.1 g of the sample to be tested is subjected to microwave digestion using 3 mL of concentrated nitric acid and 9 mL of concentrated hydrochloric acid, and after digestion, 50 mL of a volumetric flask is added to constant volume, and then the content of the target element is determined by ICAP-7000 ICP-OES.

[0316] (4) Electrochemical performance test

[0317] Capacity retention rate:

[0318] The above battery monomer is subjected to two-stage charge-discharge test by LAND test system in a 25℃ oven. The first-stage capacity calibration C0: 5 min standing, constant current charging to 4.2V at 900mA; then, constant voltage charging at 4.2V, and the charging is stopped when the current value is 60mA, standing for 30 min; then, constant current discharging at 900mA, and the discharging is stopped when the voltage is 3.0V, standing for 30 min; the discharge capacity is recorded as C0. The capacity calibration is performed every 200 cycles, and C0 is retested.

[0319] Second cycle test: constant current charge to 4.2V at 900mA, then constant voltage charge at 4.2V, when the current cut-off value is 60mA, stand for 10min, then constant current discharge at 900mA, when the voltage cut-off value is 3.0V, start the charge-discharge cycle, cycle number is set to 1000. The first cycle charge capacity: constant current charge to 4.2V at 900mA, constant voltage charge to the capacity corresponding to the current cut-off value of 60mA at 4.2V. In the test process, the first cycle corresponds to n = 1, the second cycle corresponds to n = 2, …, the 1000th cycle corresponds to n = 1000, and the discharge capacity of each cycle is recorded as Cn. The ratio of the discharge capacity Cn of each cycle to the initial discharge capacity Co is recorded as the capacity retention rate per cycle.

[0320] DC resistance:

[0321] Third DC resistance test: stand for 5min, constant current charge to 4.2V at 900mA, then constant voltage charge at 4.2V, when the current cut-off value is 60mA, stand for 30min, then constant current discharge at 900mA, when the voltage cut-off value is 0.5Co, stop, stand for 30min, the voltage is recorded as V1, then DC discharge at 4Co current (A) for 30s, the battery voltage is recorded as V2, stand for 30min, DC resistance = (V1-V2) / 4Co.

[0322] The performance of the separator and the performance test results of the battery cell provided by Examples 1-19 and Comparative Examples 1-2 are shown in Tables 3 and 4, respectively.

[0323] Table 3

[0324] Table 4

[0325] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limiting; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the specification of the present application. In particular, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present 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 battery cell, characterized by, The positive electrode sheet, the negative electrode sheet, and the separator between the positive electrode sheet and the negative electrode sheet, the separator comprising a base film and a material coating layer provided on at least one surface of the base film, the material coating layer comprising mesoporous fibrous substances and mesoporous particles, at least part of the mesoporous particles being distributed between the mesoporous fibrous substances.

2. The battery cell of claim 1, wherein, The mesoporous fibrous substances satisfy at least one of the following characteristics (1) to (4): (1) The length of the mesoporous fibrous substances is 0.5 μm to 5 μm; (2) The diameter of the mesoporous fibrous substances is 50 nm to 100 nm; (3) The aspect ratio of the mesoporous fibrous substances is 10 to 100; (4) The pore diameter of the mesoporous fibrous substances is 5 nm to 20 nm.

3. The battery cell according to claim 1 or 2, wherein The morphology of the mesoporous fibrous substances includes at least one of rod-like, columnar, linear, tubular, rod-like, and fibrous, and the material of the mesoporous fibrous substances includes at least one of silicon oxide, aluminum oxide, and magnesium oxide.

4. The battery cell of any one of claims 1 to 3, wherein, The mesoporous particles satisfy at least one of the following characteristics (1) to (4): (1) the mesoporous particles have a specific surface area of 100-500 m 2 / g; (2) the mesoporous particles have a pore volume of 0.2 to 0.6 cm3 / g 3 / mg; (3) The particle size of the mesoporous particles is 50 nm to 500 nm; (4) The pore diameter of the mesoporous particles is 5 nm to 20 nm.

5. The battery cell of any one of claims 1 to 4, wherein, The mesoporous particles include at least one of mesoporous silicon oxide, mesoporous aluminum oxide, and mesoporous magnesium oxide.

6. The battery cell of any one of claims 1 to 5, wherein, The surface of at least one material of the mesoporous fibrous substances and the mesoporous particles is connected with a chemical group, and the chemical group includes amino, carboxyl, and ethylenediamine tetraethyl.

7. The battery cell of any one of claims 1 to 6, wherein, The material coating layer further includes solid particles, and the solid particles include at least one of silicon oxide, barium sulfate, boehmite, and montmorillonite.

8. The battery cell of any one of claims 1 to 7, wherein, The material coating layer further includes a binder, and the binder includes a water-soluble binder.

9. The battery cell of any one of claims 1 to 8, wherein, The material coating layer includes a first coating layer, and the first coating layer includes the mesoporous fibrous substances and the mesoporous particles.

10. The battery cell of any one of claims 1 to 9, wherein, The material coating layer includes a first coating layer and a second coating layer stacked, and the second coating layer includes the mesoporous fibrous substances and the mesoporous particles. The positive electrode sheet, the negative electrode sheet, and the separator are in a wound structure, and the separator includes a plurality of flat regions and a plurality of corner regions alternately connected, and at least one corner region of the separator is provided with the second coating layer, and the second coating layer is provided on the surface of the first coating layer away from the base film.

11. The battery cell of claim 10, wherein the cathode comprises a lithium metal oxide. The first coating layer and the second coating layer independently include at least one of the solid particles and the binder.

12. The battery cell of claim 11, wherein, Based on the total mass of the first coating layer, the content of the mesoporous fibrous substances in the first coating layer is 10 wt% to 40 wt%, the content of the mesoporous particles in the first coating layer is 10 wt% to 80 wt%, and the content of the solid particles in the first coating layer is 0 wt% to 80 wt%.

13. The battery cell of claim 11, wherein, Based on the total mass of the second coating layer, the content of the mesoporous fibrous substances in the second coating layer is 10 wt% to 40 wt%, the content of the mesoporous particles in the second coating layer is 10 wt% to 80 wt%, and the content of the solid particles in the second coating layer is 0 wt% to 80 wt%.

14. The battery cell of any one of claims 10 to 13, characterized in that, characterized in that, The thickness of the base film is 3 μm to 10 μm; and / or the first coating layer has a thickness of 0.5-3 μm; and / or the second coating layer has a thickness of 0.5-1 μm.

15. The battery cell as described in claim 9, characterized in that, The separator further comprises an adhesive layer disposed on at least a portion of the surface of the first coating layer away from the base film.

16. The battery cell of any one of claims 1 to 15, wherein, The separator satisfies at least one of the following characteristics (1)-(4): (1) The porosity of the separator is 35-50%; (2) The wettability diffusion length of the separator is 30-100 mm; (3) the diaphragm has a longitudinal tensile strength of 2000-5000 kg / cm 2 ; (4) the transverse tensile strength of the diaphragm is 2500-6000 kg / cm 2 .

17. A lithium manganate battery cell characterized in that, A battery cell comprising the separator of any one of claims 1-16.

18. A method of producing a battery cell, characterized by, A method comprising the following steps: dispersing the mesoporous fibers and mesoporous particles in a solvent to obtain a material coating slurry; coating the material coating slurry on at least one surface of a base film to form a material coating layer, thereby obtaining a separator; assembling the separator with a positive electrode sheet and a negative electrode sheet to obtain a battery cell.

19. A battery device characterized by comprising: A plurality of battery cells of any one of claims 1-16 or a plurality of lithium manganate battery cells of claim 17.

20. An energy storage device, comprising: A plurality of battery cells of any one of claims 1-16, a plurality of lithium manganate battery cells of claim 17, or a plurality of battery devices of claim 19.

21. An energy storage system characterized by, A power conversion device and an energy storage device of claim 20, wherein the power conversion device is configured to electrically connect a power generation device and the energy storage device.

22. An electrical device, comprising: A battery cell of any one of claims 1-16, a lithium manganate battery cell of claim 17, a battery device of claim 19, an energy storage device of claim 20, or an energy storage system of claim 21, wherein the battery cell or the battery device is configured to store or provide electrical energy.

23. A charging network characterized by A charging pile and an energy storage device of claim 20 or an energy storage system of claim 21, wherein the energy storage device is configured to provide electrical energy to the charging pile.

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