Sodium metal battery, preparation method thereof and power utilization device

Abstract

The invention belongs to the technical field of batteries, and particularly relates to a sodium metal battery, a preparation method thereof and a power utilization device. The sodium metal battery comprises a positive pole piece and a negative pole piece, wherein the negative pole piece comprises a negative current collector and a sodium metal layer positioned on at least one side surface of the negative current collector; the isolating membrane is positioned between the positive pole piece and the negative pole piece; the isolating membrane comprises a base membrane and a first coating located on at least one side surface of the base membrane, and at least part of the first coating faces the sodium metal layer; the first coating has a compressive deformation amount of 20%-80% in the sodium metal battery. The design mode provided by the invention is beneficial to improving the safety of the battery.

Description

Technical Field

[0001] This application relates to the field of batteries, specifically to a sodium metal battery and its preparation method and power device. Background Technology

[0002] Secondary batteries are widely used in various consumer electronics and electric vehicles due to their outstanding characteristics such as light weight, no pollution, and no memory effect. Among them, lithium-ion batteries have a very wide range of applications in portable electronic devices and electric vehicles.

[0003] As the application of rechargeable batteries becomes more and more widespread, the requirements for battery performance are also becoming higher and higher. Summary of the Invention

[0004] In view of the above problems, this application provides a sodium metal battery, a method for preparing the same, and an electrical device thereof. The separator in the sodium metal battery can provide a buffer for the deposition of sodium metal layer on the negative electrode, thereby improving the safety of the sodium metal battery by reducing the amount of sodium dendrites generated.

[0005] In a first aspect, this application provides a sodium metal battery, which includes a positive electrode and a negative electrode. The negative electrode includes a negative current collector and a sodium metal layer located on at least one side surface of the negative current collector.

[0006] The sodium metal battery also includes a separator membrane located between the positive electrode and the negative electrode.

[0007] The isolation membrane includes a base membrane and a first coating located on at least one side of the surface of the base membrane, with at least a portion of the first coating facing the sodium metal layer;

[0008] The first coating has a compressibility of 20% to 80% in the aforementioned sodium metal battery.

[0009] In some embodiments of this application, the porosity of the first coating without compressive deformation is A1;

[0010] The porosity of the first coating under 20% to 80% compressive deformation is A2;

[0011] The porosity of the aforementioned base membrane is A0;

[0012] The condition A2 ≤ A0 < A1 is satisfied.

[0013] In some embodiments of this application, the porosity A1 of the first coating without compressive deformation is 40% to 90%;

[0014] The porosity A2 of the first coating under 20% to 80% compressive deformation is 20% to 45%;

[0015] The porosity A0 of the aforementioned base membrane is 30% to 50%.

[0016] In some embodiments of this application, the air permeability of the above-mentioned separator is ≤350s / 100cc.

[0017] In some embodiments of this application, the air permeability of the above-mentioned separator is 200s / 100cc to 350s / 100cc.

[0018] In some embodiments of this application, the air permeability of the above-mentioned separator is 200s / 100cc to 300s / 100cc.

[0019] In some embodiments of this application, the material of the first coating includes any one or more of thermoplastic polyester elastomer, thermoplastic dynamic vulcanized rubber, and thermoplastic polyurethane rubber.

[0020] In some embodiments of this application, the average relative molecular mass of the above-mentioned thermoplastic polyester elastomer is 100,000 to 1,500,000, in g / mol.

[0021] and / or;

[0022] The average relative molecular mass of the above-mentioned thermoplastic dynamic vulcanized rubber is 50,000 to 1,000,000, in g / mol.

[0023] and / or;

[0024] The average relative molecular mass of the aforementioned thermoplastic polyurethane rubber is 50,000 to 1,000,000, with units of g / mol.

[0025] In some embodiments of this application, the thermoplastic polyester elastomer comprises a first hard segment and a first soft segment, wherein the mass ratio of the first hard segment to the first soft segment is (5-70):(30-95); the first hard segment comprises any one or more of polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polylactic acid, and polybutylene adipate; and the first soft segment comprises any one or more of polyethylene glycol ether, polypropylene glycol ether, polybutylene glycol ether, polylactide, polyglycolic acid, polycaprolactone, polyethylene oxide, polypropylene oxide, polytetrahydrofuran, polybutane oxide, and polyepoxychloropropane.

[0026] and / or;

[0027] The aforementioned thermoplastic dynamic vulcanized rubber comprises thermoplastic resin and rubber, wherein the mass ratio of thermoplastic resin to rubber is (10-80):(20-90); the thermoplastic resin comprises any one or more of polypropylene, polyethylene, polystyrene, polyvinyl chloride, thermoplastic elastomer, polybutylene terephthalate, nylon, polyphenylene ether, and polycarbonate; the rubber comprises any one or more of ethylene-propylene-diene monomer rubber, natural rubber, nitrile rubber, styrene-butadiene rubber, isoprene rubber, butyl rubber, ethylene propylene diene monomer rubber, ethylene-vinyl acetate copolymer, acrylate rubber, and ethylene-acrylate copolymer.

[0028] and / or;

[0029] The aforementioned thermoplastic polyurethane rubber includes a second hard segment and a second soft segment, wherein the mass ratio of the second hard segment to the second soft segment is (10-80):(20-90); the second hard segment includes any one or more of polyethylene terephthalate, polyethylene adipate, polyether polyurethane, polycarbonate polyurethane, and polyether ester polyurethane; the second soft segment includes any one or more of polytetrahydrofuran, polypropylene oxide, polyethylene glycol, polypropylene glycol, and polybutanediol.

[0030] In some embodiments of this application, the first coating contains an adhesive, the adhesive comprising 5% to 40% by mass in the coating.

[0031] In some embodiments of this application, at least a portion of the first coating faces the aforementioned positive electrode sheet.

[0032] In some embodiments of this application, the separator includes a second coating that faces the positive electrode sheet;

[0033] The second coating contains an inorganic filler, which includes one or more of boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon oxide, tin dioxide, titanium oxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, hafnium dioxide, cerium oxide, zirconium titanate, barium titanate, and magnesium fluoride.

[0034] In some embodiments of this application, the thickness of the sodium metal layer is 5 μm to 100 μm.

[0035] In some embodiments of this application, a conductive layer is provided between the negative electrode current collector and the sodium metal layer;

[0036] The conductive layer includes one or more of carbon-based conductive materials and conductive polymer materials;

[0037] The carbon-based conductive material includes any one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0038] The conductive polymer material includes any one or more of polyphenylene, polypyrrole, polyacetylene, polyaniline, polythiophene, and polypyridine.

[0039] In some embodiments of this application, the negative electrode includes a negative current collector, a conductive layer, and a sodium metal layer, wherein the conductive layer is disposed close to the negative current collector, and the sodium metal layer is disposed away from the negative current collector.

[0040] In some embodiments of this application, the thickness of the negative electrode current collector is 5 μm to 60 μm.

[0041] A second aspect of this application is to provide a method for preparing a sodium metal battery, comprising the following steps:

[0042] Preparation of the isolation membrane: Elastomer particles and binder are dispersed in an organic solvent to form a slurry. The slurry is coated on at least one side of the base membrane and dried to form a first coating.

[0043] A sodium metal battery is formed by assembling a separator, a positive electrode, and a negative electrode together.

[0044] In some embodiments of this application, the elastomeric particles have one or more morphologies, including spherical, near-spherical, regular, or irregular polygons.

[0045] In some embodiments of this application, the volumetric particle size distribution Dv50 of the elastomer particles is 3 μm to 50 μm.

[0046] In some embodiments of this application, the specific surface area (BET) of the elastomer particles is 0.5 m². 2 / g~15m 2 / g.

[0047] In some embodiments of this application, the elastomer particles include any one or more of thermoplastic polyester elastomers, thermoplastic dynamic vulcanized rubbers, and thermoplastic polyurethane rubbers.

[0048] In some embodiments of this application, the above-mentioned elastomer particles have a porous structure, which includes mesopores with an average pore size of 2 nm to 50 nm.

[0049] In some embodiments of this application, the mass ratio between the elastomer particles and the binder is (60% to 95%): (5% to 40%).

[0050] In some embodiments of this application, the adhesive comprises any one or more of the following: methyl methacrylate monomer copolymers and / or homopolymers, sugar monomer copolymers and / or homopolymers, acrylic monomer copolymers and / or homopolymers, styrene monomer copolymers and / or homopolymers, butadiene monomer copolymers and / or homopolymers, phenolic monomer copolymers and / or homopolymers, aldehyde monomer copolymers and / or homopolymers, diamine monomer copolymers and / or homopolymers, dianhydride monomer copolymers and / or homopolymers, benzene ring monomer copolymers and / or homopolymers, or derivatives thereof, or modified thereof.

[0051] A third aspect of this application is to provide an electrical device comprising a sodium metal battery as described in the first aspect or a sodium metal battery prepared by the preparation method described in the second aspect.

[0052] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0053] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0054] Figure 1 This is a schematic diagram of the battery structure of some embodiments of this application;

[0055] Figure 2 This is an exploded structural diagram of a battery according to some embodiments of this application;

[0056] Figure 3 This is a schematic diagram of the vehicle structure according to some embodiments of this application;

[0057] Figure 4 This is a schematic diagram of the battery pack structure according to some embodiments of this application;

[0058] Figure 5 This is a schematic diagram of the structure of one of the sodium metal batteries according to some embodiments of this application;

[0059] Figure 6 This is a schematic diagram of the structure of the separator membrane in some embodiments of this application;

[0060] Figure 7A , Figure 7B and Figure 8 This is a schematic diagram of the structure of a sodium metal battery according to some embodiments of this application;

[0061] Figure 9 This is a schematic diagram of the structure of the negative electrode sheet in some embodiments of this application;

[0062] The reference numerals in the detailed embodiments are as follows:

[0063] 10000, vehicles;

[0064] 1000, Battery; 2000, Controller; 3000, Motor;

[0065] 100. Battery cell;

[0066] 200. Box body; 210. First part; 220. Second part;

[0067] 10. Secondary batteries;

[0068] 101. Housing; 102. Electrode assembly; 103. Cover plate;

[0069] 1. Negative electrode plate; 11. Negative current collector; 12. Sodium metal layer; 13. Conductive layer;

[0070] 2. Positive electrode plate;

[0071] 3. Separating membrane; 31. Base film; 32. First coating; 33. Second coating;

[0072] First direction: the x-axis of the coordinate axis, or it can be the stacking direction or the thickness direction of the separator film;

[0073] The y-axis of the coordinate axis represents the length or width of the isolation membrane. Detailed Implementation

[0074] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the sodium metal battery, its preparation method, and its power application. However, unnecessary details may be omitted. For example, detailed descriptions of well-known facts and repetitive descriptions of identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0075] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is also expected that ranges of 60–110 and 80–120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0076] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0077] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0078] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0079] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0080] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0081] Unless otherwise specified, in this application, the terms "first," "second," etc., are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features.

[0082] Unless otherwise specified, in this application, the term "multiple" means two or more (including two), similarly, "multiple sets" means two or more (including two sets), and "multiple pieces" means two or more (including two pieces).

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

[0084] Sodium metal batteries have the advantage of high energy density; however, they are prone to short circuits during repeated charge and discharge cycles. The reason for this may be that the sodium metal anode undergoes continuous volume changes during repeated sodium insertion and extraction, which can easily lead to sodium dendrite formation. These dendrites can pierce or "escape" from the separator, causing the positive and negative electrode plates to overlap, resulting in a short circuit. This short circuit, occurring when the battery is overcharged, can easily cause the battery to catch fire or even explode, posing a significant safety risk.

[0085] To address the aforementioned technical problems, this application provides a sodium metal battery, comprising a positive electrode and a negative electrode. The negative electrode includes a negative current collector and a sodium metal layer located on at least one side surface of the negative current collector. The sodium metal battery further includes a separator between the positive and negative electrodes. The separator includes a base film and a first coating located on at least one side surface of the base film, with at least a portion of the first coating facing the sodium metal layer. The first coating in the sodium metal battery has a compressibility deformation of 20% to 80%.

[0086] The separator in this sodium metal battery provides a buffer for the deposition of the sodium metal layer on the negative electrode, thereby improving the safety of the sodium metal battery by reducing the amount of sodium dendrites formed. At the same time, the pressure exerted by the formed sodium dendrites on the coating at a certain location of the separator is easily dispersed to other locations, reducing the probability of puncturing the separator and further improving the safety of the sodium metal battery.

[0087] Therefore, the sodium metal battery provided in this application is beneficial for improving battery safety. Simultaneously, the sodium metal battery possesses a relatively high energy density, and safe use at this energy density helps ensure the stability of the battery's cycle capacity retention rate. Thus, the sodium metal battery provided in this application enhances the user experience. The sodium metal battery may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte composed of the aforementioned sodium metal battery. The outer packaging of the sodium metal battery can be a hard shell, such as a hard plastic shell, aluminum shell, or steel shell. The outer packaging of the sodium metal battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic, including but not limited to polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0088] This application does not impose any particular limitation on the shape of the sodium metal battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 This is an example of a sodium metal battery with a square structure (secondary battery 10).

[0089] According to some embodiments of this application, reference is made to Figure 2 The outer packaging may include a housing 101 and a cover plate 103. The housing 101 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates forming a receiving cavity. The housing 101 has an opening communicating with the receiving cavity, and the cover plate 103 can be placed over the opening to close the receiving cavity. The positive electrode, negative electrode, and separator may be formed into an electrode assembly 102 by a winding process or a stacking process. The electrode assembly 102 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 102. The secondary battery 10 may contain one or more electrode assemblies 102, which can be selected by those skilled in the art according to specific practical needs.

[0090] The electrode assembly 102 provided in this application, when used in a secondary battery, helps improve the battery's performance. This secondary battery can be a power source for an electrical device or an energy storage unit for that device. These devices are used in power applications, such as mobile devices (e.g., mobile phones, laptops), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, and energy storage systems. The energy storage system can store electrical energy as needed and output it when appropriate. For example, an energy storage system may include one or more batteries. This system can store electrical energy during off-peak hours and provide power to users or electrical equipment during peak hours. The energy storage system provided in this application can be any power system that requires an energy storage device.

[0091] For ease of explanation, some embodiments of this application are illustrated using a vehicle as an example of an electrical device.

[0092] Please refer to Figure 3 , Figure 3 This is a schematic diagram of the structure of a vehicle 10000 provided in some embodiments of this application. The vehicle 10000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery 1000 is disposed inside the vehicle 10000, and the battery 10000 can be located at the bottom, front, or rear of the vehicle 10000. The battery 10000 can be used to power the vehicle 10000; for example, the battery 10000 can serve as the operating power source for the vehicle 10000. The vehicle 10000 may also include a controller 2000 and a motor 3000. The controller 2000 is used to control the battery 10000 to supply power to the motor 3000, for example, to meet the power needs of the vehicle 10000 during startup, navigation, and driving.

[0093] In some embodiments of this application, the battery 1000 can not only serve as the operating power source for the vehicle 10000, but also as the driving power source for the vehicle 10000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 10000.

[0094] Please refer to Figure 4 , Figure 4 This is an exploded view of a battery 1000 provided in some embodiments of this application. The battery 1000 includes a housing 200 and a battery cell 100. A conventional battery cell includes a primary battery or a secondary battery. This application specifically protects a secondary battery 10. The battery cell 100 is housed within the housing 200. The housing 200 provides space for the battery cell 100, and the housing 200 can adopt various structures.

[0095] In some embodiments, the housing 200 may include a first portion 210 and a second portion 220, which overlap each other, and together define a receiving space for accommodating the secondary battery 100. The second portion 220 may be a hollow structure with one open end, and the first portion 210 may be a plate-like structure, with the first portion 210 covering the open side of the second portion 220 so that the first portion 210 and the second portion 220 together define the receiving space; alternatively, the first portion 210 and the second portion 220 may both be hollow structures with one open side, with the open side of the first portion 210 covering the open side of the second portion 220. Of course, the housing 200 formed by the first portion 210 and the second portion 220 may be of various shapes, such as a cylinder, a cuboid, etc.

[0096] In battery 1000, there can be multiple battery cells 100, which can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 100 are connected in both series and parallel configurations. Multiple battery cells 100 can be directly connected in series, parallel, or in a mixed manner, and then the entire assembly of the multiple battery cells 100 is housed within housing 200. Alternatively, battery 1000 can also be composed of multiple battery cells 100 first connected in series, parallel, or in a mixed manner to form battery modules, and then these modules are connected in series, parallel, or in a mixed manner to form a whole, which is also housed within housing 200. Battery 1000 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 100.

[0097] Sodium metal battery

[0098] This application discloses a sodium metal battery in some embodiments, the sodium metal battery including a positive electrode and a negative electrode, the negative electrode including a negative current collector and a sodium metal layer located on at least one side surface of the negative current collector; the sodium metal battery also includes a separator between the positive electrode and the negative electrode; the separator includes a base film and a first coating located on at least one side surface of the base film, at least a portion of the first coating facing the sodium metal layer; the first coating has a compressibility deformation of 20% to 80% in the sodium metal battery.

[0099] The positive electrode, separator, and negative electrode in this application can be formed into a sodium metal battery using a winding or stacking process. Specifically, this application... Figure 5 The diagram illustrates a secondary battery 10 (sodium metal battery) formed using a stacking method, combined with... Figure 5It is known that a negative electrode 1 or a positive electrode 2 is placed between two adjacent separators 3, and the negative electrode 1 and the positive electrode 2 are alternately arranged along the stacking direction (coordinate axis x direction). The number and size of the negative electrode 1 and / or the positive electrode 2 can be selected according to the actual situation, and will not be elaborated in this application. Furthermore, this application... Figure 5 The image only illustrates one type of lamination method; other lamination or winding methods are within the scope of protection of this application.

[0100] This application is in Figure 6 The diagram illustrates that the separator 3 includes a base film 31 and a first coating 32 located on at least one side surface of the base film 31. This application... Figure 6 The diagram only shows the first coating 32 being applied to one side of the surface of the base film 31.

[0101] The deformation of the first coating in this application refers to the thickness of the coating before compression deformation as h1, and the thickness after compression deformation as h2, calculated as (h1-h2) / h1×100%. The coating thickness refers to the distance between the two end faces of the coating along the battery stacking direction, which can be measured using a conventional laser thickness gauge.

[0102] The separator in this sodium metal battery provides a buffer for the deposition of the sodium metal layer on the negative electrode, thereby improving the safety of the sodium metal battery by reducing the amount of sodium dendrite formation. At the same time, even if sodium dendrites are formed, the pressure exerted by the dendrites on the coating at a certain location on the separator is easily dispersed to other locations, reducing the probability of separator puncture and further improving the safety of the sodium metal battery.

[0103] In some embodiments, this application discloses that the porosity of the first coating without compressibility deformation is A1;

[0104] The porosity of the first coating under 20% to 80% compressive deformation is A2;

[0105] The porosity of the base membrane is A0; satisfying A2≤A0<A1.

[0106] The first coating in the separator of this application has a certain porosity to enable normal conduction of ions in the battery. At the same time, the first coating with a certain porosity can also disperse the pressure exerted by sodium dendrites at a certain location on the coating at that location, which helps to reduce the probability of puncturing the separator.

[0107] In some embodiments, this application discloses that the porosity A1 of the first coating without compressive deformation is 40% to 90%;

[0108] The porosity A2 of the first coating under 20% to 80% compressive deformation is 20% to 45%.

[0109] The porosity A0 of the base membrane is 30%–50%.

[0110] The methods for measuring the porosity of the isolation membrane in this application include various conventional methods in the art, such as the gravimetric method: measuring the volume of the base film or coating, and calculating the volume of the internal pores as the porosity using the true density of the base film or coating material; it also includes the mercury porosimetry method, with the testing standard referring to GB / T21650.2-2008 "Mercury Porosimetry and Gas Adsorption Method for Determination of Pore Size Distribution and Porosity of Solid Materials Part 2: Gas Adsorption Method for Analysis of Mesopores and Macropores", and also includes methods for measuring or calculating the porosity using the following methods:

[0111] For example, after drying, the coating sample or base film sample is cut into a square sample of approximately 20mm × 20mm. The thickness and actual side length are measured using a digital micrometer and vernier calipers, and its volume is calculated as V. Its weight is then measured as M0. The square sample is then immersed in the electrolyte and soaked for 2 hours at room temperature and in air. After soaking, the electrolyte liquid adsorbed on the surface is removed, and its weight is measured as M. t The porosity of the coated sample or the base film sample satisfies the following mathematical relationship:

[0112] Porosity = (M) t -M0) / ρ×V×100%;

[0113] In the above mathematical formula, ρ represents the density of the electrolyte, with units of mm. 3 / g, where V is the volume of a square sample of the coating or base film, in mm. 3 Weights M0 and M t The unit is g, and the weight measuring instrument is a 0.1 / 1000 balance. The models of the 0.1 / 1000 balance, digital micrometer, and vernier caliper include, but are not limited to, any conventional models in this field.

[0114] The method for measuring the porosity of a first coating with a compressive deformation between 20% and 80% in this application includes: first applying pressure to the coating to form a coating sample with a compressive deformation between 20% and 80%, and then performing the same measurement method as described above on the coating sample.

[0115] In these embodiments, this application discloses that the porosity A1 of the first coating without compressive deformation is any one of 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, or any one of the above ranges.

[0116] In these embodiments, this application discloses that the porosity A2 of the first coating under 20% to 80% compressibility deformation is any one of 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, or any one of the above ranges.

[0117] In these embodiments, this application discloses that the porosity A0 of the base membrane is any one of 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, or any one of the above range values.

[0118] In these embodiments, this application discloses that the first coating of the separator has a certain compressibility deformation in the battery, thus its porosity changes, while the base film has almost no compressibility in the battery, and its porosity does not change. Under the premise of satisfying the above-mentioned porosity, the first coating and base film of the separator in this application can not only ensure the normal conduction of ions in the battery, but also disperse the pressure exerted by sodium dendrites at a certain location on the coating at that location, which helps to reduce the probability of puncturing the separator.

[0119] In some embodiments, this application discloses that the air permeability of the separator is ≤350s / 100cc.

[0120] In some embodiments, this application discloses that the air permeability of the separator is 200s / 100cc to 350s / 100cc.

[0121] In some embodiments, this application discloses that the air permeability of the separator is 200s / 100cc to 300s / 100cc.

[0122] The permeability of the separator in this application refers to the amount of gas that passes through the separator under a certain time and pressure. The industry commonly uses the Gurley value, which indicates the time required for 100 mL of oxygen to pass through a 1 square inch (equivalent to 1 square centimeter) separator at a pressure of 1.22 kPa. Generally, the permeability of a separator is correlated with its thickness, pore size, porosity, and pore tortuosity. This application, by selecting an appropriate separator permeability, can reduce the probability of sodium dendrites puncturing the separator while ensuring normal ion conduction in the battery.

[0123] This application discloses in some embodiments that the material of the first coating includes one or more of thermoplastic polyester elastomer, thermoplastic dynamic vulcanized rubber, and thermoplastic polyurethane rubber.

[0124] The thermoplastic polyester elastomer (TPEE) in this application is a block copolymer, wherein the block copolymer comprises crystalline polyester hard segments with high melting point and high hardness and amorphous polyether or polyester soft segments with low glass transition temperature. The crystalline polyester hard segments play a physical crosslinking role, and the amorphous polyether or polyester soft segments endow the block copolymer with high resilience.

[0125] This application discloses in these embodiments that the average relative molecular mass of the thermoplastic polyester elastomer is 100,000 to 1,500,000, in g / mol.

[0126] The average relative molecular mass of this application refers to its average relative molar mass for a single component, and to the ratio between the mass and molar mass of the mixed components for a mixed component. The average relative molecular mass of the thermoplastic polyester elastomer is any one of 100,000, 200,000, 300,000, 400,000, 500,000, 600,000, 700,000, 800,000, 900,000, 1,000,000, 1,100,000, 1,200,000, 1,300,000, 1,400,000, and 1,500,000.

[0127] This application discloses in these embodiments a thermoplastic polyester elastomer comprising a first hard segment and a first soft segment, wherein the mass ratio of the first hard segment to the first soft segment is (5-70):(30-95); the first hard segment comprises any one or more of polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polylactic acid (PLA), and polybutylene adipate (PBAT); and the first soft segment comprises any one or more of polyethylene glycol ether, polypropylene glycol ether, polybutylene glycol ether, polylactide, polyglycolic acid, polycaprolactone, polyethylene oxide (PEO), polypropylene oxide (PPG), polytetrahydrofuran (PTMEG), polybutyroxene oxide (PEB), and polyepoxychloropropane (PEC).

[0128] In these embodiments, this application also discloses that the mass ratio of the first hard segment to the first soft segment in the thermoplastic polyester elastomer is any one of 5:95, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, and 70:30.

[0129] The thermoplastic dynamic vulcanized rubber (TPV) of this application refers to a blend material prepared by dynamic vulcanization technology. It exhibits the high elasticity of rubber at room temperature and can melt and plasticize at high temperatures, combining the excellent properties of both rubber and thermoplastic resin. Therefore, the thermoplastic dynamic vulcanized rubber (TPV) mainly consists of two parts: a thermoplastic resin as the continuous phase and a rubber as the dispersed phase. In these embodiments, this application discloses that the average relative molecular mass of the thermoplastic dynamic vulcanized rubber is 50,000 to 1,000,000, in g / mol, and the meaning of average relative molecular mass remains the same as described above. The average relative molecular mass of the thermoplastic dynamic vulcanized rubber is any one of 50,000, 100,000, 200,000, 300,000, 400,000, 500,000, 600,000, 700,000, 800,000, 900,000, and 1,000,000.

[0130] This application discloses in these embodiments a thermoplastic dynamic vulcanized rubber comprising a thermoplastic resin and rubber, wherein the mass ratio of the thermoplastic resin to the rubber is (10-80):(20-90). The thermoplastic resin includes one or more of polypropylene (PP), polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), thermoplastic elastomer (TPE), polybutylene terephthalate (PBT), nylon, polyphenylene ether, and polycarbonate. The rubber includes one or more of ethylene-propylene-diene monomer rubber (EPDM), natural rubber (NR), nitrile rubber (NBR), styrene-butadiene rubber (SBR), isoprene rubber, butyl rubber, ethylene-vinyl acetate copolymer, acrylate rubber, and ethylene-acrylate copolymer. This application also discloses in these embodiments a thermoplastic resin to rubber mass ratio of 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, and 80:20.

[0131] The thermoplastic polyurethane rubber (TPU) of this application is a type of elastomer that can be plasticized by heat and dissolved by solvents, and is a (AB) nThis application discloses a block linear polymer, where A is a high molecular weight (1000-6000) polyester or polyether, B is a diol containing 2-12 straight-chain carbon atoms, and the intersegmental chemical structure of A and B is a diisocyanate. In these embodiments, the thermoplastic polyurethane rubber disclosed has an average relative molecular weight of 50,000 to 1,000,000, in g / mol. The average relative molecular weight of the thermoplastic polyurethane rubber in this application is any one of 50,000, 100,000, 200,000, 300,000, 400,000, 500,000, 600,000, 700,000, 800,000, 900,000, and 1,000,000.

[0132] This application also discloses a thermoplastic polyurethane rubber comprising a second hard segment and a second soft segment, wherein the mass ratio of the second hard segment to the second soft segment is (10-80):(20-90); the second hard segment comprises any one or more of poly(terephthalate) glycol (PBT), poly(PTT), polyether polyurethane (a hard segment formed by the reaction of polyether glycol and isocyanate), polycarbonate polyurethane (a hard segment formed by the reaction of polycarbonate glycol and isocyanate), and polyether ester polyurethane; the second soft segment comprises any one or more of polytetrahydrofuran (PTMG), polypropylene oxide (PPG), polyethylene glycol (PEG), polypropylene glycol (PPG), and polybutanediol (PBG). In these embodiments, this application discloses a mass ratio of the second hard segment to the second soft segment of any one of 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, and 80:20.

[0133] This application discloses in some embodiments that the first coating includes an adhesive, wherein the adhesive accounts for 5% to 40% of the first coating by mass.

[0134] In the above embodiments, this application discloses that the first coating material comprises one or more of thermoplastic polyester elastomer, thermoplastic dynamic vulcanized rubber, and thermoplastic polyurethane rubber. In addition, it includes an adhesive for bonding the first coating materials together and for bonding the first coating materials to a base film. In these embodiments, this application discloses that the mass percentage content of the adhesive in the first coating is any one of 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, and 40%, or any value within the range described above.

[0135] This application also discloses specific types of adhesives in these embodiments, including at least one of the following: acrylate monomer copolymers and / or homopolymers; polyvinyl alcohol; vinylidene fluoride polymers; vinylidene fluoride-hexafluoropropylene copolymers; vinylidene fluoride-pentafluoropropylene copolymers; vinylidene fluoride-tetrafluoropropylene copolymers; vinylidene fluoride-trifluoropropylene copolymers; vinylidene fluoride-perfluorobutene copolymers; vinylidene fluoride-tetrafluoroethylene copolymers; vinylidene fluoride-trifluoroethylene copolymers; vinylidene fluoride-trifluorochloroethylene copolymers; or vinylidene fluoride-vinyl fluoride copolymers; sugar monomer copolymers and / or homopolymers; acrylic monomer copolymers and / or homopolymers; styrene monomer copolymers and / or homopolymers; butadiene monomer copolymers and / or homopolymers; phenolic monomer copolymers and / or homopolymers; aldehyde monomer copolymers and / or homopolymers; diamine monomer copolymers and / or homopolymers; dianhydride monomer copolymers and / or homopolymers; benzene ring monomer copolymers and / or homopolymers; or derivatives thereof, or modifiers thereof.

[0136] The monomers in the acrylic monomer copolymers and / or homopolymers of this application include any one or more of the following: methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-propyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.

[0137] The carbohydrate monomer copolymers and / or homopolymers of this application include carboxymethyl cellulose and sodium alginate. The acrylic monomer copolymers and / or homopolymers of this application include polyacrylic acid. The styrene monomer copolymers and / or homopolymers of this application include styrene-butadiene rubber and styrene monomer-butadiene monomer-styrene monomer block copolymers. The aldehyde monomer copolymers and / or homopolymers of this application include phenolic resins. The diamine monomer copolymers and / or homopolymers of this application include polyimide.

[0138] In some embodiments of this application, the first coating 32 of the separator 3 is disposed toward the sodium metal layer 12 of the negative electrode 1, specifically as follows: Figure 7A Indication.

[0139] In some embodiments of this application, the first coating 32 of the separator 3 is disposed toward the sodium metal layer 12 of the negative electrode 1, and the first coating 32 is also disposed toward the positive electrode 2, as specifically as follows: Figure 7B Indication.

[0140] Combination Figure 7A and 7BIt is known that the first coating 32 of the separator 3 of this application is bonded to the sodium metal layer 12 of the negative electrode 1, and the first coating 32 has a certain compressive deformation in the sodium metal battery, that is, there is stress between the sodium metal layer 12 and the first coating 32 of the separator 3. Under the guidance of this stress, the deposition and peeling process of the sodium metal layer 12 mainly proceeds along the interface, thereby reducing the amount of sodium dendrites generated and improving the safety of the sodium metal battery.

[0141] This application discloses in some embodiments that the separator 3 includes a second coating 33 facing the positive electrode 2. (Specifically combined with...) Figure 8 It is understood that the separator 3 includes a base film 31, a first coating 32 located on one side of the base film 31, and a second coating 33 located on the other side of the base film 31. The first coating 32 faces the sodium metal layer 12 of the negative electrode 1, and the second coating 33 faces the positive electrode 2. The material of the second coating 33 is different from that of the first coating 32. Specifically, in these embodiments, this application discloses that the second coating 33 contains an inorganic filler, which includes any one or more of boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon oxide, tin dioxide, titanium oxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, hafnium dioxide, cerium oxide, zirconium titanate, barium titanate, and magnesium fluoride.

[0142] The above-mentioned design method adopted in this application not only facilitates the reduction of sodium dendrite formation on the negative electrode sheet of the battery, but also helps to improve the thermal stability and mechanical strength of the separator, further reducing the probability of sodium dendrite puncturing the separator.

[0143] In some embodiments of this application, a conductive layer 13 is provided between the negative electrode current collector 11 and the aforementioned sodium metal layer 12, specifically as follows: Figure 9 Indication. Figure 9 The illustration shows a conductive layer 13 disposed on one side of the negative electrode current collector 11. This application also includes conductive layers 13 disposed on both sides of the negative electrode current collector 11. The conductive layer 13 can be formed entirely or partially on the surface of the negative electrode current collector 11. In the following embodiments, this application focuses on the conductive layer 13 being entirely formed on both sides of the negative electrode current collector 11. Furthermore, the formation method of the conductive layer 13 on the surface of the negative electrode current collector 11 includes any method conventional in the art, such as coating, deposition, etc.

[0144] In these embodiments, this application discloses that the conductive layer includes one or more of carbon-based conductive materials and conductive polymer materials; wherein, the carbon-based conductive materials include any one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; and the conductive polymer materials include any one or more of polyphenylene, polypyrrole, polyacetylene, polyaniline, polythiophene, and polypyridine.

[0145] The conductive layer provided in this application can effectively reduce the overpotential during sodium metal layer deposition, thereby alleviating uneven metal deposition at the negative electrode interface or reducing the number of sodium dendrites. In other words, this application uses a conductive layer on the surface of the negative electrode current collector to reduce the probability of sodium dendrite formation.

[0146] In some embodiments of this application, the thickness of the negative electrode current collector is disclosed to be 5 μm to 60 μm; the thickness of the negative electrode current collector in this application includes the thickness along a certain direction, as described in the specification. Figure 9 The distance between the two opposite end faces of the negative electrode current collector along the x-axis of the coordinate system is measured using methods conventional in the art, such as direct measurement or calculation after taking a photograph. In these embodiments, this application discloses that the thickness of the negative electrode current collector is any one of 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, and 60μm.

[0147] In some embodiments, this application discloses that the thickness of the sodium metal layer is 5 μm to 100 μm.

[0148] The sodium metal battery provided in this application deposits a sodium metal layer on the surface of the negative electrode current collector during the first charge. The microstructure of the sodium metal layer can be obtained by scanning the negative electrode sheet of the sodium metal battery using methods such as transmission electron microscopy (TEM). Further measurements can then be taken to obtain the sodium metal layer along, for example... Figure 9 The distance between two opposite end faces along the x-axis of the coordinate system is the thickness value. In some embodiments of this application, the thickness of the conductive layer is disclosed to be 100 nm to 7 μm. As mentioned above, the thickness of the conductive layer in this application includes the thickness along a certain direction, as described in the specification. Figure 9 The distance between two opposite end faces of the conductive layer in the x-axis direction of the coordinate system can be measured using methods conventional in the field, such as direct measurement or calculation after taking a picture.

[0149] Preparation method of sodium metal battery

[0150] This application discloses a method for preparing a sodium metal battery in some embodiments, the method comprising the following steps:

[0151] Preparation of the isolation membrane: Elastomer particles and binder are dispersed in an organic solvent to form a slurry. The slurry is coated on at least one side of the base membrane and dried to form a first coating.

[0152] A sodium metal battery is formed by assembling a separator, a positive electrode, and a negative electrode together.

[0153] This application discloses in some embodiments that the elastomeric particles have one or more morphologies, including spherical, near-spherical, regular, or irregular polygons. These morphologies of the elastomeric particles facilitate the fabrication of coatings.

[0154] In some embodiments, this application discloses that the volumetric particle size distribution Dv50 of the elastomer particles is 3 μm to 50 μm.

[0155] The method for measuring the volumetric particle size distribution (Dv50) of the elastomer particles in this application includes: obtaining the volumetric particle size distribution curve according to GB / T 19077-2016, and taking the particle size corresponding to the cumulative volumetric distribution percentage reaching 50% as the average particle size (Dv50). The testing instrument can be a Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd., UK. Deionized water is used as the solvent, and the particles are ultrasonically treated for approximately 5 minutes before testing.

[0156] This application discloses in these embodiments that the volumetric particle size distribution Dv50 of the elastomer particles is 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, etc. The value can be any one of the following: μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm, or any one of the values ​​in the above range.

[0157] This application discloses in some embodiments that the specific surface area (BET) of the elastomer particles is 0.5 m². 2 / g~15m 2 / g.

[0158] The method for measuring the specific surface area (BET) of the elastomer particles in this application includes: referring to GB / T 19587-2004, using the nitrogen adsorption specific surface area analysis method, and calculating the specific surface area of ​​the particles using the BET (Brunauer Emmett Teller) method. The testing instrument can be a TRISTAR II 3020 specific surface area and porosity analyzer from Micromeritics, USA.

[0159] This application discloses in these embodiments that the specific surface area (BET) of the elastomer particles is 0.5 m². 2 / g, 1m2 / g, 1.5m 2 / g、2m 2 / g, 2.5m 2 / g、3m 2 / g, 3.5m 2 / g、4m 2 / g, 4.5m 2 / g、5m 2 / g, 5.5m 2 / g、6m 2 / g, 6.5m 2 / g、7m 2 / g, 7.5m 2 / g、8m 2 / g, 8.5m 2 / g、9m 2 / g, 9.5m 2 / g, 10m 2 / g, 10.5m 2 / g、11m 2 / g, 11.5m 2 / g、12m 2 / g, 12.5m 2 / g、13m 2 / g, 13.5m 2 / g、14m 2 / g, 14.5m 2 / g, 15m 2 Any one of / g or any one of the above range values.

[0160] This application discloses in some embodiments that the elastomer particles include one or more of thermoplastic polyester elastomers, thermoplastic dynamic vulcanized rubbers, and thermoplastic polyurethane rubbers.

[0161] The material of the first coating has been described in the above embodiments, and will not be repeated here.

[0162] This application discloses in some embodiments that the elastomer particles have a porous structure, the porous structure including mesopores, the average pore size of which is 2 nm to 50 nm.

[0163] This application discloses in these embodiments that the elastomer particles have a porous structure, and the average pore size of the pores in the porous structure is measured by any method conventional in the art. For example, the distribution of each pore can be measured using conventional testing instruments, and the number of each pore can be obtained by statistical analysis. Then, the average pore size can be calculated using mathematical functions. Alternatively, the pore volume and specific surface area of ​​the porous structure can be obtained using adsorption and desorption isotherms. Based on the relevant pore model, the average pore size is obtained by dividing the pore volume by the specific surface area and multiplying by the model coefficient. For example, using an ASAP2460 physical adsorption analyzer, the dried and degassed elastomer particle sample is placed in liquid nitrogen, and the amount of nitrogen adsorbed is measured by adjusting different test pressures. Adsorption and desorption isotherms are plotted, and the pore volume and specific surface area of ​​the elastomer particles are obtained from the adsorption and desorption isotherms, thereby calculating the average pore size of the elastomer particles.

[0164] In these embodiments, this application discloses that the elastomer particles have a porous structure, so that the formed first coating can meet the porosity requirements while having the above-mentioned compressive deformation.

[0165] In some embodiments, this application also discloses that the elastomer particles have a solid structure. During the process of forming the first coating, a pore-forming agent is added to the slurry. For example, the pore-forming agent includes any one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, vinylene carbonate, diethylene glycol dimethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, and dipropylene glycol dimethyl ether. The amount of pore-forming agent added is 100% to 1000% of the weight of the adhesive, so that the formed first coating can meet the above-mentioned porosity requirements.

[0166] In some embodiments, this application discloses that the mass ratio of the elastomer particles to the above-mentioned binder is (60% to 95%): (5% to 40%).

[0167] In these embodiments, this application discloses that the first coating comprises elastomer particles and a binder, wherein the mass ratio of the elastomer particles to the binder is any one of 60%:40%, 70%:30%, 80%:20%, 90%:10%, 95%:5% or any one of the above range values.

[0168] This application discloses in some embodiments that the adhesive includes any one or more of the following: acrylate monomer copolymers and / or homopolymers, polyvinyl alcohol, vinylidene fluoride polymers, vinylidene fluoride-hexafluoropropylene copolymers, vinylidene fluoride-pentafluoropropylene copolymers, vinylidene fluoride-tetrafluoropropylene copolymers, vinylidene fluoride-trifluoropropylene copolymers, vinylidene fluoride-perfluorobutene copolymers, vinylidene fluoride-tetrafluoroethylene copolymers, vinylidene fluoride-trifluoroethylene copolymers, vinylidene fluoride-trifluorochloroethylene copolymers, or vinylidene fluoride-vinyl fluoride copolymers, sugar monomer copolymers and / or homopolymers, acrylic monomer copolymers and / or homopolymers, styrene monomer copolymers and / or homopolymers, butadiene monomer copolymers and / or homopolymers, phenolic monomer copolymers and / or homopolymers, aldehyde monomer copolymers and / or homopolymers, diamine monomer copolymers and / or homopolymers, dianhydride monomer copolymers and / or homopolymers, benzene ring monomer copolymers and / or homopolymers, or derivatives thereof, or modified thereof.

[0169] This application discloses in these embodiments that the second coating comprises an inorganic filler and a binder, wherein the types of inorganic fillers are as described above, and the types of binders in the second coating are as listed in the binder types of the first coating described above. The mass ratio of inorganic filler to binder is (75% to 95%):(5% to 25%). The second coating is formed by dispersing the inorganic filler and binder in an organic solvent and then coating them onto one side surface of a base film, followed by drying to form the second coating.

[0170] [Isolation membrane]

[0171] According to some embodiments of this application, as described above, the separator includes a base film and a first coating located on at least one side of the base film, the first coating having a compressibility deformation of 20% to 80% after being subjected to a positive pressure of 1 MPa to 3 MPa.

[0172] The first coating deformation in this application refers to the coating thickness as h1 when it is not compressed and h2 when it is compressed, calculated as (h1-h2) / h1×100%. The coating thickness refers to the difference between the two end faces of the coating along the battery stacking direction, which can be measured using a conventional laser thickness gauge.

[0173] In some embodiments, this application discloses that the porosity of the first coating without compressive deformation is A1, the porosity of the first coating with compressive deformation of 20% to 80% is A2, and the porosity of the base film is A0; satisfying A2≤A0<A1.

[0174] In some embodiments, this application discloses that the porosity A1 of the first coating is 40% to 90% without compressibility deformation.

[0175] The porosity A2 of the first coating is 20% to 45% under 20% to 80% compressive deformation.

[0176] The porosity A0 of the base membrane is 30%–50%.

[0177] The methods for measuring the porosity of the separator membrane in this application include various conventional methods in the art, such as the gravimetric method: measuring the volume of the separator membrane and calculating the volume of the pores in the separator membrane using the true density of the separator membrane material, which is the porosity; it also includes the mercury porosimetry method, with the testing standard referring to GB / T21650.2-2008 "Mercury Porosimetry and Gas Adsorption Method for Determination of Pore Size Distribution and Porosity of Solid Materials Part 2: Gas Adsorption Method for Analysis of Mesopores and Macropores", and also includes methods for measuring or calculating the porosity using the following methods:

[0178] For example, after drying, the coating sample or base film sample is cut into a square sample of approximately 20mm × 20mm. The thickness and actual side length are measured using a digital micrometer and vernier calipers, and its volume is calculated as V. Its weight is then measured as M0. The square sample is then immersed in the electrolyte and soaked for 2 hours at room temperature and in air. After soaking, the electrolyte liquid adsorbed on the surface is removed, and its weight is measured as M. t The porosity of the coated sample or the base film sample satisfies the following mathematical relationship:

[0179] Porosity = (M) t -M0) / ρ×V×100%;

[0180] In the above mathematical formula, ρ represents the density of the electrolyte, with units of mm. 3 / g, where V is the volume of a square sample of the coating or base film, in mm. 3 Weights M0 and M t The unit is g, and the weight measuring instrument is a 0.1 / 1000 balance. The models of the 0.1 / 1000 balance, digital micrometer, and vernier caliper include, but are not limited to, any conventional models in this field.

[0181] The method for measuring the porosity of a first coating with a compressive deformation between 20% and 80% in this application includes: first applying pressure to the coating to form a coating sample with a compressive deformation between 20% and 80%, and then performing the same measurement method as described above on the coating sample.

[0182] In these embodiments, this application discloses that the porosity A1 of the first coating without compressive deformation is any one of 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, or any one of the above ranges.

[0183] In these embodiments, this application discloses that the porosity A2 of the first coating under 20% to 80% compressibility deformation is any one of 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, or any one of the above ranges.

[0184] In some embodiments, this application discloses that the air permeability of the separator is ≤350s / 100cc.

[0185] In some embodiments, this application discloses that the air permeability of the separator is 200s / 100cc to 350s / 100cc.

[0186] In some embodiments, this application discloses that the air permeability of the separator is 200s / 100cc to 300s / 100cc.

[0187] The permeability of the separator in this application refers to the amount of gas that passes through the separator under a certain time and pressure. The industry commonly uses the Gurley value, which indicates the time required for 100 mL of oxygen to pass through a 1 square inch (equivalent to 1 square centimeter) separator at a pressure of 1.22 kPa. Generally, the permeability of a separator is correlated with its thickness, pore size, porosity, and pore tortuosity. This application, by selecting an appropriate separator permeability, can reduce the probability of sodium dendrites puncturing the separator while ensuring normal ion conduction in the battery.

[0188] This application discloses in some embodiments that the material of the first coating includes one or more of thermoplastic polyester elastomer, thermoplastic dynamic vulcanized rubber, and thermoplastic polyurethane rubber.

[0189] The thermoplastic polyester elastomer (TPEE) in this application is a block copolymer, wherein the block copolymer comprises crystalline polyester hard segments with high melting point and high hardness and amorphous polyether or polyester soft segments with low glass transition temperature. The crystalline polyester hard segments play a physical crosslinking role, and the amorphous polyether or polyester soft segments endow the block copolymer with high resilience.

[0190] This application discloses in these embodiments that the average relative molecular mass of the thermoplastic polyester elastomer is 100,000 to 1,500,000, in g / mol.

[0191] The average relative molecular mass of this application refers to its average relative molar mass for a single component, and to the ratio between the mass and molar mass of the mixed components for a mixed component. The average relative molecular mass of the thermoplastic polyester elastomer is any one of 100,000, 200,000, 300,000, 400,000, 500,000, 600,000, 700,000, 800,000, 900,000, 1,000,000, 1,100,000, 1,200,000, 1,300,000, 1,400,000, and 1,500,000.

[0192] This application discloses in these embodiments a thermoplastic polyester elastomer comprising a first hard segment and a first soft segment, wherein the mass ratio of the first hard segment to the first soft segment is (5-70):(30-95); the first hard segment comprises any one or more of polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polylactic acid (PLA), and polybutylene adipate (PBAT); and the first soft segment comprises any one or more of polyethylene glycol ether, polypropylene glycol ether, polybutylene glycol ether, polylactide, polyglycolic acid, polycaprolactone, polyethylene oxide (PEO), polypropylene oxide (PPG), polytetrahydrofuran (PTMEG), polybutyroxene oxide (PEB), and polyepoxychloropropane (PEC).

[0193] In these embodiments, this application also discloses that the mass ratio of the first hard segment to the first soft segment in the thermoplastic polyester elastomer is any one of 5:95, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, and 70:30.

[0194] The thermoplastic dynamic vulcanized rubber (TPV) of this application refers to a blend material prepared by dynamic vulcanization technology. It exhibits the high elasticity of rubber at room temperature and can melt and plasticize at high temperatures, combining the excellent properties of both rubber and thermoplastic resin. Therefore, the thermoplastic dynamic vulcanized rubber (TPV) mainly consists of two parts: a thermoplastic resin as the continuous phase and a rubber as the dispersed phase. In these embodiments, this application discloses that the average relative molecular mass of the thermoplastic dynamic vulcanized rubber is 50,000 to 1,000,000, in g / mol, and the meaning of average relative molecular mass remains the same as described above. The average relative molecular mass of the thermoplastic dynamic vulcanized rubber is any one of 50,000, 100,000, 200,000, 300,000, 400,000, 500,000, 600,000, 700,000, 800,000, 900,000, and 1,000,000.

[0195] This application discloses in these embodiments a thermoplastic dynamic vulcanized rubber comprising a thermoplastic resin and rubber, wherein the mass ratio of the thermoplastic resin to the rubber is (10-80):(20-90). The thermoplastic resin includes one or more of polypropylene (PP), polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), thermoplastic elastomer (TPE), polybutylene terephthalate (PBT), nylon, polyphenylene ether, and polycarbonate. The rubber includes one or more of ethylene-propylene-diene monomer rubber (EPDM), natural rubber (NR), nitrile rubber (NBR), styrene-butadiene rubber (SBR), isoprene rubber, butyl rubber, ethylene-vinyl acetate copolymer, acrylate rubber, and ethylene-acrylate copolymer. This application also discloses in these embodiments a thermoplastic resin to rubber mass ratio of 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, and 80:20.

[0196] The thermoplastic polyurethane rubber (TPU) of this application is a type of elastomer that can be plasticized by heat and dissolved by solvents, and is a (AB) n This application discloses a block linear polymer, where A is a high molecular weight (1000-6000) polyester or polyether, B is a diol containing 2-12 straight-chain carbon atoms, and the intersegmental chemical structure of A and B is a diisocyanate. In these embodiments, the thermoplastic polyurethane rubber disclosed has an average relative molecular weight of 50,000 to 1,000,000, in g / mol. The average relative molecular weight of the thermoplastic polyurethane rubber in this application is any one of 50,000, 100,000, 200,000, 300,000, 400,000, 500,000, 600,000, 700,000, 800,000, 900,000, and 1,000,000.

[0197] This application also discloses a thermoplastic polyurethane rubber comprising a second hard segment and a second soft segment, wherein the mass ratio of the second hard segment to the second soft segment is (10-80):(20-90); the second hard segment comprises any one or more of poly(terephthalate) glycol (PBT), poly(PTT), polyether polyurethane (a hard segment formed by the reaction of polyether glycol and isocyanate), polycarbonate polyurethane (a hard segment formed by the reaction of polycarbonate glycol and isocyanate), and polyether ester polyurethane; the second soft segment comprises any one or more of polytetrahydrofuran (PTMG), polypropylene oxide (PPG), polyethylene glycol (PEG), polypropylene glycol (PPG), and polybutanediol (PBG). In these embodiments, this application discloses a mass ratio of the second hard segment to the second soft segment of any one of 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, and 80:20.

[0198] This application discloses in some embodiments that the first coating includes an adhesive, wherein the adhesive accounts for 5% to 40% of the first coating by mass.

[0199] In the above embodiments, this application discloses that the first coating material comprises one or more of thermoplastic polyester elastomer, thermoplastic dynamic vulcanized rubber, and thermoplastic polyurethane rubber. In addition, it includes an adhesive for bonding the first coating materials together and for bonding the first coating materials to a base film. In these embodiments, this application discloses that the mass percentage content of the adhesive in the first coating is any one of 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, and 40%, or any value within the range described above.

[0200] This application also discloses specific types of adhesives in these embodiments, including at least one of the following: acrylate monomer copolymers and / or homopolymers; polyvinyl alcohol; vinylidene fluoride polymers; vinylidene fluoride-hexafluoropropylene copolymers; vinylidene fluoride-pentafluoropropylene copolymers; vinylidene fluoride-tetrafluoropropylene copolymers; vinylidene fluoride-trifluoropropylene copolymers; vinylidene fluoride-perfluorobutene copolymers; vinylidene fluoride-tetrafluoroethylene copolymers; vinylidene fluoride-trifluoroethylene copolymers; vinylidene fluoride-trifluorochloroethylene copolymers; or vinylidene fluoride-vinyl fluoride copolymers; sugar monomer copolymers and / or homopolymers; acrylic monomer copolymers and / or homopolymers; styrene monomer copolymers and / or homopolymers; butadiene monomer copolymers and / or homopolymers; phenolic monomer copolymers and / or homopolymers; aldehyde monomer copolymers and / or homopolymers; diamine monomer copolymers and / or homopolymers; dianhydride monomer copolymers and / or homopolymers; benzene ring monomer copolymers and / or homopolymers; or derivatives thereof, or modifiers thereof.

[0201] The monomers in the acrylic monomer copolymers and / or homopolymers of this application include any one or more of the following: methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-propyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.

[0202] The carbohydrate monomer copolymers and / or homopolymers of this application include carboxymethyl cellulose and sodium alginate. The acrylic monomer copolymers and / or homopolymers of this application include polyacrylic acid. The styrene monomer copolymers and / or homopolymers of this application include styrene-butadiene rubber and styrene monomer-butadiene monomer-styrene monomer block copolymers. The aldehyde monomer copolymers and / or homopolymers of this application include phenolic resins. The diamine monomer copolymers and / or homopolymers of this application include polyimide.

[0203] This application discloses in some embodiments that the base film is made of one or more of polyethylene, polypropylene, poly(p-phenylene terephthalamide), polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, and polyamide.

[0204] This application discloses in some embodiments that the separator membrane includes a base membrane and a first coating located on both sides of the base membrane.

[0205] This application discloses in some embodiments that the separator membrane includes a base membrane, a first coating located on one side surface of the base membrane, and a second coating located on the other side surface of the base membrane.

[0206] This application discloses in some embodiments that the second coating includes an inorganic filler comprising one or more of boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon oxide, tin dioxide, titanium oxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, hafnium dioxide, cerium oxide, zirconium titanate, barium titanate, and magnesium fluoride.

[0207] This application discloses in some embodiments that the second coating further includes an adhesive of the same type as the adhesive in the first coating.

[0208] This application discloses in some embodiments that the adhesive content in the second coating is 5% to 25% by mass. In these embodiments, the application discloses that the adhesive content in the second coating is any one of 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, or 25% by mass, or any value within a range.

[0209] [Negative electrode plate]

[0210] According to some embodiments of this application, as described above, the negative electrode sheet includes a negative current collector and a sodium metal layer located on at least one side of the surface of the negative current collector.

[0211] According to some embodiments of this application, a conductive layer is provided between the negative electrode current collector and the sodium metal layer described above.

[0212] According to some embodiments of this application, the material of the negative electrode current collector includes at least one of metal foil, metal foam current collector, metal mesh current collector, carbon felt current collector, carbon cloth current collector, carbon paper current collector, and composite current collector. In these embodiments, this application also discloses that the metal foil includes copper foil, aluminum foil, stainless steel foil, iron foil, zinc foil, titanium foil, etc. In these embodiments, this application also discloses that the metal foam current collector includes copper foam, aluminum foam, zinc foam, etc. In these embodiments, this application also discloses that the metal mesh current collector includes copper mesh, aluminum mesh, etc. Meanwhile, the negative electrode current collector can also be a composite current collector formed by combining metal foil and metal foam, or a composite current collector formed by combining metal foil and metal mesh, or a composite current collector formed by combining metal foil and polymer base film; this application does not impose any particular limitation.

[0213] According to some embodiments of this application, the conductive layer includes one or more of carbon-based conductive materials and conductive polymer materials; wherein, the carbon-based conductive materials include any one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; the conductive polymer materials include any one or more of polyphenylene, polypyrrole, polyacetylene, polyaniline, polythiophene, and polypyridine.

[0214] According to some embodiments of this application, the thickness of the negative electrode current collector is 5 μm to 60 μm; the thickness of the negative electrode current collector in this application includes the thickness along a certain direction, as described in the specification. Figure 9 The distance between the two opposite end faces of the negative electrode current collector along the x-axis of the coordinate system is measured using methods conventional in the art, such as direct measurement or calculation after taking a photograph. In these embodiments, this application discloses that the thickness of the negative electrode current collector is any one of 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, and 60μm.

[0215] According to some embodiments of this application, the thickness of the sodium metal layer is 5 μm to 100 μm. In the sodium metal battery provided by this application, a sodium metal layer is deposited on the surface of the negative electrode current collector during the first charge. This can be achieved by photographing, for example, scanning the negative electrode sheet of the sodium metal battery using a transmission electron microscope (TEM), to obtain the microstructure of the sodium metal layer. Further measurements can then be taken to obtain the sodium metal layer along... Figure 9 The distance between two opposite end faces along the x-axis of the coordinate system is the thickness value. In these embodiments, this application discloses that the thickness of the sodium metal layer is any one of 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, and 100μm. According to some embodiments of this application, the thickness of the conductive layer is 100nm to 7μm. As mentioned above, the thickness of the conductive layer in this application includes along a certain direction, as described in the specification. Figure 9 The distance between two opposite end faces of the conductive layer in the x-axis direction of the coordinate system can be measured using methods conventional in the field, such as direct measurement or calculation after taking a picture.

[0216] [Positive electrode plate]

[0217] According to some embodiments of this application, the positive electrode sheet includes a positive current collector and a positive electrode film layer located on at least one side surface of the positive current collector. The positive electrode sheet includes a positive current collector and a positive electrode film layer located on at least one side surface of the positive current collector, the positive electrode film layer comprising a sodium ion positive electrode active material.

[0218] According to some embodiments of this application, the sodium-ion cathode active material includes, but is not limited to, at least one of sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds. However, this application is not limited to these materials, and other conventionally known materials that can be used as cathode active materials for sodium-ion batteries may also be used.

[0219] In this application, the transition metal in the sodium transition metal oxide can be one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce.

[0220] The sodium transition metal oxide in this application can be a layered transition metal oxide with the chemical formula Na. x M y O z M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, 0 < x ≤ 1, 0 < y ≤ 1, 1 < z ≤ 2.

[0221] The polyanionic compounds in this application may contain sodium ions, transition metal ions, or tetrahedral (YO4) ions. n- The valence state. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si, where n represents (YO4). n- The price state.

[0222] The polyanionic compound in this application can also be a tetrahedral compound containing sodium ions (YO4). n- Anionic unit, polyhedral unit (ZO) y ) m+ And a class of compounds with optional halide anions. Y can be at least one of P, S, and Si, and n represents (YO4). n- The valence state; Z represents a transition metal, which can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; m represents (ZO) y ) m+ The valence state; the halogen can be at least one of F, Cl and Br.

[0223] The polyanionic compounds in this application include sodium iron pyrophosphate (NaFePO4), sodium vanadium phosphate (Na3V2(PO4)3), NaM'PO4F (M' is one or more of V, Fe, Mn and Ni), and Na3(VO4)2(PO4)3. y )2(PO4)2F 3-2y At least one of (0≤y≤1).

[0224] The polyanionic compounds in this application include any one or more of sodium vanadium trifluorophosphate, sodium vanadium fluorophosphate, sodium vanadium phosphate, sodium iron pyrophosphate, and sodium iron pyrophosphate.

[0225] The Prussian blue compounds in this application may contain sodium ions, transition metal ions, and cyanide ions (CN). - A class of compounds. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Prussian blue compounds are, for example, Na. a Me b Me' c (CN)6, wherein Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co and Zn, 0 < a ≤ 2, 0 < b < 1, 0 < c < 1.

[0226] This application discloses in some embodiments that the positive electrode film layer may further include a conductive agent to improve the conductivity of the positive electrode. This application does not impose specific limitations on the type of conductive agent, which can be selected according to actual needs. As an example, the conductive agent may be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers.

[0227] This application discloses in some embodiments that the positive electrode film layer may further include an adhesive to firmly bond the sodium ion positive electrode active material and an optional conductive agent to the positive electrode current collector. This application does not specifically limit the type of adhesive, which can be selected according to actual needs. As an example, the adhesive may include, but is not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.

[0228] This application discloses in some embodiments that the positive electrode current collector can be a conductive carbon sheet, a metal foil, a carbon-coated metal foil, a porous metal plate, or a composite current collector. The conductive carbon material of the conductive carbon sheet can be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers. The metal material of the metal foil, carbon-coated metal foil, and porous metal plate can each be independently selected from at least one of copper, aluminum, nickel, and stainless steel. The composite current collector can be a composite current collector formed by combining a metal foil with a polymer base film.

[0229] The positive current collector is one or more of the following: copper foil, aluminum foil, nickel foil, stainless steel foil, stainless steel mesh, and carbon-coated aluminum foil, with aluminum foil being preferred.

[0230] The above-mentioned positive electrode sheet can be prepared according to conventional methods in the art. Typically, sodium ion positive electrode active material and optional conductive agent and binder are dispersed in a solvent (e.g., N-methylpyrrolidone, abbreviated as NMP) to form a uniform positive electrode slurry. The positive electrode slurry is coated on both sides of the positive electrode current collector, and after drying and cold pressing, the positive electrode sheet is obtained.

[0231] Electrolyte

[0232] In some embodiments of this application, the sodium metal battery further includes an electrolyte, which can be liquid, solid, or gel-like. Solid state refers to a solid electrolyte, liquid state to a liquid electrolyte, and gel-like state to a gel electrolyte. The sodium metal battery of this application uses a liquid electrolyte, i.e., an electrolyte solution. This electrolyte solution contains an electrolyte salt and an organic solvent. The electrolyte salt can be any type conventional in the art, including, but not limited to, inorganic metal salts such as NaClO4, NaAsF6, NaPF6, NaBF4, NaSbF6, NaSO3F, NaN(FSO2)2, etc.; fluorine-containing organometallic salts such as NaCF3SO3, NaN(FSO2)(CF3SO2), NaN(CF3SO2)2, NaN(C2F5SO2)2, cyclic 1,3-hexafluoropropane disulfonylimide sodium, cyclic 1,2-tetrafluoroethane disulfonylimide sodium, NaN(CF3SO2)(C4F5SO2)2, etc. 9SO2), NaC(CF3SO2)3, NaPF4(CF3)2, NaPF4(C2F5)2, NaPF4(CF3SO2)2, NaPF4(C2F5SO2)2, NaBF2(CF3)2, NaBF2(C2F5)2, NaBF2(CF3SO2)2, NaBF2(C2F5SO2)2, etc.; and metal salts containing dicarboxylic acid complexes, such as sodium bis(oxalate oxy)borate, sodium difluorooxalate oxyborate, sodium tri(oxalate oxy)phosphate, sodium difluorobis(oxalate oxy)phosphate, sodium tetrafluoro(oxalate oxy)phosphate, etc.

[0233] According to some embodiments of this application, the concentration of the electrolyte salt in the electrolyte is 0.1 mol / L to 4 mol / L. In these embodiments, this application discloses that the concentration of the electrolyte salt is any one of 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.5 mol / L, 2.8 mol / L, 3 mol / L, 3.2 mol / L, 3.5 mol / L, 3.8 mol / L, and 4 mol / L, or any one of the above ranges.

[0234] As described above, the organic solvent comprises one or more of carboxylic acid esters, carbonates, and ethers. Specifically, the carboxylic acid esters comprise one or more of ethyl acetate (EA), methyl acetate (MA), ethyl propionate (EP), propyl acetate (PA), methyl propionate (MP), methyl butyrate (MB), ethyl butyrate (EB), and 1,4-butyrolactone (GBL); the carbonates comprise one or more of ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl ethyl carbonate (EMC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl carbonate (BC), and fluoroethylene carbonate (FEC). The ethers comprise at least one of tetrahydrofuran, dimethyl tetrahydrofuran, tetrahydropyran, dimethyl tetrahydropyran, 1,2-dimethoxyethane, dipropylene glycol dimethyl ether, or dimethyl phthalate. The organic solvents of this application further include one or two of nitrile solvents and sulfone solvents. The nitrile solvents include one or more of acetonitrile (AN), glutaronitrile (GLN), and adiponitrile (ADN). The sulfone solvents include at least one or a combination of two of sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0235] According to some embodiments of this application, the electrolyte further comprises a film-forming stabilizer, which includes a positive electrode film-forming stabilizer and a negative electrode film-forming stabilizer. The positive electrode film-forming stabilizer includes carbonate additives and / or sulfate additives. The carbonate additives include one or more of vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), vinyl ethylene carbonate (VEC), and dioctyl carbonate (CC). The sulfate additives include cyclic sulfonate additives and / or alkyl sulfate additives; further, the cyclic sulfonate additives include one or more of 1,3-propanesulfonate lactone (PS), propenesulfonate lactone (PES), and 3-fluoro1,3-propanesulfonate lactone (FPS); the alkyl sulfate additives include one or more of vinyl sulfate (DTD), diethyl sulfate (DES), and dimethyl sulfate (DMS). The negative electrode film-forming stabilizer includes one or more of sodium boron salts, phosphorus-containing sodium salts, and sulfur-containing sodium salts; the sodium boron salts include sodium tetrafluoroborate (NaBF4) and sodium bis(oxalato)borate.

[0236] Sodium difluorooxalate borate (NaBOB) and sodium difluorooxalate borate (NaDFOB) are among the following: phosphorus-containing lithium salts include sodium difluorophosphate (NaPO2F2), sodium fluorophosphate (Na2PO3F), and sodium phosphate (Na3PO4). Sulfur-containing sodium salts include sodium fluorosulfonate (NaFSO3), sodium sulfate (Na2SO4), and sodium aminosulfonate (NaSO3NH2) are among the following:

[0237] The secondary battery of this application will be described in detail below with reference to specific embodiments.

[0238] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods.

[0239] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0240] This application may employ conventional inorganic chemistry techniques within the art. In the following examples, efforts have been made to ensure the accuracy of the figures used (including quantities, temperatures, reaction times, etc.), but some experimental errors and biases should be considered. Temperatures (in degrees Celsius) used in the following examples are expressed in °C, and pressures are at or near atmospheric pressure. All reagents were purchased from AR-grade suppliers, and all reactions were carried out under argon protection. Unless otherwise stated, all reagents were obtained commercially.

[0241] Experimental materials: See the table below for details.

[0242] Table 1 Solid Elastomer Particles

[0243]

[0244]

[0245] Table 2 Porous Elastomer Particles

[0246]

[0247]

[0248] Example 1-1

[0249] A sodium metal battery is provided, comprising a positive electrode, a separator and a negative electrode stacked sequentially, and an electrolyte.

[0250] Preparation of the separating membrane:

[0251] A polyethylene separator with a thickness of 7 μm was used as the base membrane (porosity A0 is 40%).

[0252] The thermoplastic polyester elastomer particles with serial number I-1 in Table 1 above are mixed with adhesive (PVDF) at a mass ratio of 80%:20% and then dispersed in organic solvent NMP and stirred to form a slurry. Then, a pore-forming agent (diethyl carbonate) is added to the slurry, and the amount of pore-forming agent added is 500% of the weight of the adhesive.

[0253] The above slurry was applied to both sides of the base film and dried to form a first coating with a thickness of 31.5 μm.

[0254] Preparation of electrolyte:

[0255] In an environment with a water content of less than 10 ppm, non-aqueous organic solvents ethylene carbonate, diethyl carbonate, and dimethyl carbonate are mixed in a volume ratio of 1:1:1 to obtain a solvent. Sodium hexafluorophosphate is added to the solvent to prepare an electrolyte with a sodium hexafluorophosphate concentration of 1 mol / L.

[0256] Preparation of positive electrode sheet:

[0257] Na3V2(PO4)3 (93.8 wt%), conductive carbon black (3.0 wt%), PVDF (2.5 wt%), dispersant (hydrogenated nitrile rubber, 0.3 wt%), and residual alkali remover (0.4 wt%) were mixed. The residual alkali remover included one or more of commonly used weak acids in the art, such as maleic anhydride, benzoic acid, and salicylic acid; maleic anhydride was chosen in this embodiment. Then, N-methylpyrrolidone (NMP) was added and stirred to disperse, forming a positive electrode slurry. After stirring the prepared oil-based positive electrode slurry, the viscosity was adjusted to 10000 mPa·s. The slurry was not separated into layers. Then, the slurry coating weight was controlled at 200 mg / 1540.25 cm³ using a double-sided, double-cavity coating device. 2The coating is applied to Al foil, and after double-sided coating, it is dried, cold-pressed, slit, and prepared to obtain the positive electrode sheet.

[0258] Preparation of negative electrode sheet:

[0259] Single-walled carbon nanotubes (diameter 1–3 nm, BET 1000 m) were used. 2 A dispersion of (g) and binder (polyacrylic acid) is dispersed in NMP and stirred to form a uniform slurry. The slurry is then coated on both sides of a copper foil (8 μm thick) to form a negative electrode sheet, wherein the conductive layer has a thickness of 2 μm.

[0260] Preparation of sodium metal batteries:

[0261] The prepared positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the anode and cathode to provide isolation. The stacked electrodes yield a bare battery cell. The bare battery cell is placed in outer packaging, dried, and then injected with the electrolyte described above. Following formation and degassing processes, a sodium metal battery is obtained.

[0262] Examples 1-2

[0263] A sodium metal battery is provided. This embodiment differs from Embodiment 1-1 in that the material of the first coating in the separator is different, which is serial number I-2 in Table 1. Otherwise, it is the same as Embodiment 1-1.

[0264] Examples 1-3

[0265] A sodium metal battery is provided. This embodiment differs from Embodiment 1-1 in that the material of the first coating in the separator is different, which is serial number I-3 in Table 1. Otherwise, it is the same as Embodiment 1-1.

[0266] Comparative Example 1

[0267] A sodium metal battery is provided, which differs from Example 1-1 in that a polyethylene separator with a thickness of 7 μm is selected. Everything else remains the same as in Example 1-1.

[0268] Example 2-1

[0269] A sodium metal battery is provided. This embodiment differs from Embodiment 1-1 in that the material of the first coating in the separator is different, which is serial number II-1 in Table 1. Otherwise, it is the same as Embodiment 1-1.

[0270] Example 2-2

[0271] A sodium metal battery is provided. This embodiment differs from Embodiment 1-1 in that the material of the first coating in the separator is different, which is serial number III-1 in Table 1. Otherwise, it is the same as Embodiment 1-1.

[0272] Example 3-1

[0273] A sodium metal battery is provided. This embodiment differs from Embodiment 1-1 in that the material of the first coating in the separator is different, which is serial number IV-1 in Table 2, and no pore-forming agent is added to the slurry during the separator preparation process. Otherwise, it is the same as Embodiment 1-1.

[0274] Example 4-1

[0275] A sodium metal battery is provided. This embodiment differs from Embodiment 1-1 in that a first coating is formed on one side of the separator and a second coating is formed on the other side. The specific steps are as follows: a polyethylene separator with a thickness of 7 μm is provided as the base film (porosity A0 is 35%).

[0276] Preparation of the first slurry: The thermoplastic polyester elastomer particles with serial number I-1 in Table 1 above are mixed with the adhesive (PVDF) at a mass ratio of 80%:20% and then dispersed in the organic solvent NMP and stirred to form a slurry. Then, a pore-forming agent (diethyl carbonate) is added to the slurry, and the amount of pore-forming agent added is 500% of the weight of the adhesive to form the first slurry.

[0277] Preparation of the second slurry: Take silica (Dv50 of 3.2μm) and binder (PVDF) at a mass ratio of 90%:10%, mix them evenly, and then disperse them in the organic solvent NMP and stir to form the second slurry;

[0278] The first slurry was applied to one side of the base film, and the second slurry was applied to the other side of the base film. After drying, the thickness of the first coating was 31.5 μm, and the thickness of the second coating was 2 μm.

[0279] Example 5-1

[0280] A sodium metal battery is provided. This embodiment differs from Embodiment 1-1 in that porous elastomer particles and binder are mixed at a mass ratio of 95%:5% and then dispersed in an organic solvent NMP and stirred to form a slurry; otherwise, it remains the same as Embodiment 1-1.

[0281] Example 6-1

[0282] A sodium metal battery is provided, which differs from Example 1-1 in that the negative electrode uses a copper foil with a thickness of 8 μm, while the rest remains the same as Example 1-1.

[0283] [Performance Testing]

[0284] ① Test the compressive deformation of the coating:

[0285] The coating sample was tested using a universal testing machine (MDTC-EQ-M12-01). The sample was placed on the test stage, and a loading force was applied to the coating. The specific test steps are as follows:

[0286] Step 1: Select the isolation film to be tested: Through multi-layer superposition test, the thickness of the test coating sample must meet ≥1mm to control the error accuracy;

[0287] Step 2, Initial thickness collection: Apply initial pressure to the coating sample (try initial value ≥0.05MPa) and obtain the initial thickness of the isolation membrane sample under this constant pressure;

[0288] Step 3: Compressive Modulus Collection: Pressure is continuously applied to the coating sample until the thickness remains constant. When the pressure / stress ratio reaches an exponential inflection point, data collection is considered complete. The slope of the initial segment of the strain-stress curve corresponds to the compression of this coating sample. From this, the compressive modulus of different target samples is obtained, and the stress-strain curves are analyzed.

[0289] Step 4: Read the compression ratio and rebound ratio corresponding to the target pressure from the stress-strain curve; in this application, the compression ratio and rebound ratio corresponding to 1MPa to 3MPa are selected.

[0290] ② Test the porosity of the coating:

[0291] After drying, the coated sample was cut into square specimens of approximately 20mm × 20mm. The thickness and actual side length were measured using a digital micrometer and vernier calipers, and its volume (V) was calculated. Its weight (M0) was then measured. The square specimens were then immersed in the electrolyte solution and soaked for 2 hours at room temperature and in air. After soaking, the electrolyte adsorbed on the surface was removed, and the weight (M0) was measured again. t The porosity of the coated sample then satisfies the following mathematical relationship:

[0292] Porosity = (M) t -M0) / ρ×V×100%;

[0293] In the above mathematical formula, ρ represents the density of the electrolyte in Example 1-1, in mm³. 3 / g, V is the volume of the square sample of the coating, in mm. 3 Weights M0 and M t The unit is g, and the weight measuring instrument is a 0.1 / 1000 balance. The models of the 0.1 / 1000 balance, digital micrometer, and vernier caliper include, but are not limited to, any conventional models in this field.

[0294] The method for measuring the porosity of a first coating with a compressive deformation between 20% and 80% in this application includes: first applying pressure to the coating to form a coating sample with a compressive deformation between 20% and 80%, and then performing the same measurement method as described above on the coating sample.

[0295] ③ Test the air permeability of the separator membrane:

[0296] Specifically, refer to the MP010 Gurley method for air permeability analysis published in GB / T 458-2008. The unit of measurement for air permeability is s / 100mL (the time it takes for 100mL of gas to pass through).

[0297] ④ Test the thickness of the sodium metal layer:

[0298] The batteries prepared in the above embodiments and comparative examples were disassembled using a glove box. The negative electrode sheet was obtained for sample preparation, transferred using a vacuum transfer box, and cut into appropriately sized samples. Conductive adhesive was used to fix the samples on the sample stage, ensuring the samples were flat and had good conductivity. The Zeiss Sigma300 ion polishing system was turned on, the equipment was preheated, and initial operating parameters were set, including ion beam energy, tilt angle, and polishing time. Initial cutting was performed using a lower ion beam energy to quickly remove impurities from the sample surface. Adjust the sample stage tilt angle and use an ion beam to cut the sample cross-section at an angle to form a suitable cross-section for observation. Gradually reduce the ion beam energy and perform fine polishing on the sample surface to reduce surface damage. Perform final polishing at a lower energy until the sample surface achieves the required smoothness and clarity. After polishing, clean the sample surface with an appropriate solvent to remove residual polishing solution, dry the sample, and prepare for SEM observation: Remove the polished sample from the ion polishing system and transfer it to the sample chamber of the scanning electron microscope (SEM). Observe the sample under SEM and use the built-in functional scale of the equipment to measure the thickness of the deposited metal layer. Analyze the thickness distribution of the metal cross-section (generally, test 2-3 samples at different locations, with each sample thickness measured at 50µm intervals. Take the average thickness of the tested samples as the average thickness output. Due to consistency and testing errors, the average thickness output is retained with a 0 / 5 tail).

[0299] ⑤ At 25℃, test the battery's capacity retention rate after 200 cycles:

[0300] The batteries prepared in the examples and comparative examples were placed in a constant temperature chamber at 25°C, and their cycle life was tested according to the procedure:

[0301] 1) Let stand for 10 hours;

[0302] 2) Charge at a constant current of 0.1C to 3.65V, then charge at a constant voltage of 3.65V to 0.05C0;

[0303] 3) Let stand for 30 minutes;

[0304] 4) Discharge at a constant current of 0.1C to 1.5V;

[0305] 5) Let stand for 30 minutes;

[0306] 6) Charge at a constant current of 0.33C to 3.65V, then charge at a constant voltage of 3.65V to 0.05C.

[0307] 7) Let stand for 30 minutes;

[0308] 8) Discharge at a constant current of 0.33C to 1.5V;

[0309] 9) Let stand for 30 minutes;

[0310] 10) Repeat steps 6) to 9) a total of 3 times;

[0311] 11) Charge at 1C constant current to 3.65V, then charge at 3.65V constant voltage to 0.05C0;

[0312] 12) Let stand for 30 minutes;

[0313] 13) Discharge at a constant current of 1C to 1.5V;

[0314] 14) Let stand for 30 minutes;

[0315] Record the discharge capacity at this point, which is the initial discharge capacity.

[0316] Repeat steps 11) to 14) for a total of 200 times, and record the discharge capacity on the 200th time, which is the final discharge capacity.

[0317] The capacity retention rate after 200 cycles is 100% of the final discharge capacity / initial discharge capacity.

[0318] ⑥ At 25℃, test the battery for internal short circuits after 200 cycles:

[0319] Perform cycle charging and discharging on the battery according to the testing method described in ⑤ above:

[0320] 1) Let stand for 10 hours;

[0321] 2) Charge at a constant current of 0.1C to 3.65V, then charge at a constant voltage of 3.65V to 0.05C0;

[0322] 3) Let stand for 30 minutes;

[0323] 4) Discharge at a constant current of 0.1C to 1.5V;

[0324] 5) Let stand for 30 minutes;

[0325] 6) Charge at a constant current of 0.33C to 3.65V, then charge at a constant voltage of 3.65V to 0.05C0; record the charging capacity.

[0326] 7) Let stand for 30 minutes;

[0327] 8) Discharge at a constant current of 0.33C to 1.5V; record the discharge capacity;

[0328] 9) Let stand for 30 minutes;

[0329] Coulomb efficiency = charging capacity / discharging capacity;

[0330] 10) Repeat steps 6) to 9) a total of 3 times, calculating the coulomb efficiency according to the above formula each time;

[0331] 11) Charge at 1C constant current to 3.65V, then charge at 3.65V constant voltage to 0.05C0;

[0332] 12) Let stand for 30 minutes;

[0333] 13) Discharge at a constant current of 1C to 1.5V;

[0334] 14) Let stand for 30 minutes;

[0335] Repeat steps 11) to 14) for a total of 200 times.

[0336] If the coulomb efficiency is greater than or equal to 1.1 three times, the cell is considered to be short-circuited.

[0337] Table 3 Performance of the separating membrane

[0338]

[0339]

[0340] Table 4 Battery Performance (Part 1)

[0341] Serial Number Sodium metal layer thickness / μm Example 1-1 35.2 Examples 1-2 30.9 Examples 1-3 40.5 Comparative Example 1 45.3 Example 2-1 40.2 Example 2-2 40.8 Example 3-1 40.6 Example 4-1 42.5 Example 5-1 35.8 Example 6-1 41.3

[0342] Table 5 Battery Performance (Part Two)

[0343] Capacity retention after 200 cycles Is it short-circuited? Example 1-1 88.7％ no Examples 1-2 95.8％ no Examples 1-3 87.4％ no Comparative Example 1 15.0％ yes Example 2-1 85.4％ no Example 2-2 85.8％ no Example 3-1 86.1％ no Comparative Example 4-1 82.2％ no Example 5-1 90.3％ no Example 6-1 80.5％ no

[0344] As can be seen from the above list, the design method provided in this application can provide a buffer for the deposition of the sodium metal layer on the negative electrode, thereby improving the safety of sodium metal batteries by reducing the number of sodium dendrites formed. At the same time, the pressure exerted by the generated sodium dendrites on the coating at a certain location of the separator is easily dispersed to other locations, reducing the probability of puncturing the separator and further improving the safety of sodium metal batteries. Meanwhile, under safe use, it also helps to ensure the stability of the battery's cycle capacity retention rate.

[0345] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A sodium metal battery, characterized in that: It includes a positive electrode and a negative electrode, wherein the negative electrode includes a negative current collector and a sodium metal layer located on at least one side of the surface of the negative current collector; The sodium metal battery also includes a separator membrane located between the positive electrode and the negative electrode. The isolation membrane includes a base membrane and a first coating located on at least one side of the surface of the base membrane, with at least a portion of the first coating facing the sodium metal layer; The first coating has a compressibility of 20% to 80% in the sodium metal battery.

2. The sodium metal battery according to claim 1, characterized in that: The porosity of the first coating without compressibility deformation is A1; The porosity of the first coating under 20% to 80% compressive deformation is A2; The porosity of the base membrane is A0; The condition A2 ≤ A0 < A1 is satisfied.

3. The sodium metal battery according to claim 2, characterized in that: The porosity A1 of the first coating without compressive deformation is 40% to 90%; The porosity A2 of the first coating under 20% to 80% compressive deformation is 20% to 45%; The porosity A0 of the base membrane is 30% to 50%.

4. The sodium metal battery according to any one of claims 1 to 3, characterized in that: The air permeability of the isolation membrane is ≤350s / 100cc.

5. The sodium metal battery according to any one of claims 1 to 4, characterized in that: The air permeability of the isolation membrane is 200s / 100cc to 350s / 100cc.

6. The sodium metal battery according to any one of claims 1 to 5, characterized in that: The material of the first coating includes any one or more of thermoplastic polyester elastomer, thermoplastic dynamic vulcanized rubber, and thermoplastic polyurethane rubber.

7. The sodium metal battery according to claim 6, characterized in that: The thermoplastic polyester elastomer has an average relative molecular mass of 100,000 to 1,500,000, in g / mol. and / or; The average relative molecular mass of the thermoplastic dynamic vulcanized rubber is 50,000 to 1,000,000, in g / mol. and / or; The thermoplastic polyurethane rubber has an average relative molecular mass of 50,000 to 1,000,000, expressed in g / mol.

8. The sodium metal battery according to any one of claims 6 to 7, characterized in that: The thermoplastic polyester elastomer comprises a first hard segment and a first soft segment, wherein the mass ratio of the first hard segment to the first soft segment is (5-70):(30-95); the first hard segment comprises any one or more of polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polylactic acid, and polybutylene adipate; and the first soft segment comprises any one or more of polyethylene glycol ether, polypropylene glycol ether, polybutylene glycol ether, polylactide, polyglycolic acid, polycaprolactone, polyethylene oxide, polypropylene oxide, polytetrahydrofuran, polybutane oxide, and polyepoxychloropropane. and / or; The thermoplastic dynamic vulcanized rubber comprises a thermoplastic resin and a rubber, wherein the mass ratio of the thermoplastic resin to the rubber is (10-80):(20-90); the thermoplastic resin comprises any one or more of polypropylene, polyethylene, polystyrene, polyvinyl chloride, thermoplastic elastomer, polybutylene terephthalate, nylon, polyphenylene ether, and polycarbonate; the rubber comprises any one or more of ethylene-propylene-diene monomer rubber, natural rubber, nitrile rubber, styrene-butadiene rubber, isoprene rubber, butyl rubber, ethylene propylene diene monomer rubber, ethylene-vinyl acetate copolymer, acrylate rubber, and ethylene-acrylate copolymer. and / or; The thermoplastic polyurethane rubber includes a second hard segment and a second soft segment, wherein the mass ratio of the second hard segment to the second soft segment is (10-80):(20-90); the second hard segment includes any one or more of polyterephthalate, polyadipate, polyether polyurethane, polycarbonate polyurethane, and polyether ester polyurethane; the second soft segment includes any one or more of polytetrahydrofuran, polypropylene oxide, polyethylene glycol, polypropylene glycol, and polybutanediol.

9. The sodium metal battery according to any one of claims 1 to 8, characterized in that: The first coating contains an adhesive, and the adhesive accounts for 5% to 40% of the first coating by mass.

10. The sodium metal battery according to any one of claims 1 to 9, characterized in that: At least a portion of the first coating faces the positive electrode sheet.

11. The sodium metal battery according to any one of claims 1 to 9, characterized in that: The separator includes a second coating, which faces the positive electrode sheet. The second coating contains inorganic fillers, which include one or more of boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon oxide, tin dioxide, titanium oxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, hafnium dioxide, cerium oxide, zirconium titanate, barium titanate, and magnesium fluoride.

12. The sodium metal battery according to any one of claims 1 to 11, characterized in that: The thickness of the sodium metal layer is 5 μm to 100 μm.

13. The sodium metal battery according to any one of claims 1 to 12, characterized in that: A conductive layer is provided between the negative electrode current collector and the sodium metal layer; The conductive layer includes one or more of carbon-based conductive materials and conductive polymer materials; The carbon-based conductive material includes any one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The conductive polymer material includes any one or more of polyphenylene, polypyrrole, polyacetylene, polyaniline, polythiophene, and polypyridine.

14. The sodium metal battery according to any one of claims 1 to 13, characterized in that: The thickness of the negative electrode current collector is 5μm to 60μm.

15. A method for preparing a sodium metal battery, characterized in that: The process includes the following: Preparation of the isolation membrane: Elastomer particles and binder are dispersed in an organic solvent to form a slurry, the slurry is coated on at least one side of the base membrane, and after drying, a first coating is formed; A sodium metal battery is formed by assembling a separator, a positive electrode, and a negative electrode together.

16. The preparation method according to claim 15, characterized in that: The elastomeric particles have any one or more morphologies among spherical, near-spherical, regular, or irregular polygons. and / or; The volumetric particle size distribution Dv50 of the elastomer particles is 3 μm to 50 μm; and / or; The specific surface area (BET) of the elastomer particles is 0.5 m². 2 / g~15m 2 / g. and / or; The elastomer particles include any one or more of thermoplastic polyester elastomers, thermoplastic dynamic vulcanized rubbers, and thermoplastic polyurethane rubbers.

17. The preparation method according to any one of claims 15 to 16, characterized in that: The elastomer particles have a porous structure, which includes mesopores, and the average pore size of the mesopores is 2 nm to 50 nm.

18. The preparation method according to any one of claims 15 to 17, characterized in that: The mass ratio of the elastomer particles to the binder is (60%–95%): (5%–40%).

19. The preparation method according to any one of claims 15 to 18, characterized in that: The binder comprises any one or more of the following: acrylate monomer copolymers and / or homopolymers, polyvinyl alcohol, vinylidene fluoride polymers, vinylidene fluoride-hexafluoropropylene copolymers, vinylidene fluoride-pentafluoropropylene copolymers, vinylidene fluoride-tetrafluoropropylene copolymers, vinylidene fluoride-trifluoropropylene copolymers, vinylidene fluoride-perfluorobutene copolymers, vinylidene fluoride-tetrafluoroethylene copolymers, vinylidene fluoride-trifluoroethylene copolymers, vinylidene fluoride-trifluorochloroethylene copolymers, or vinylidene fluoride-vinyl fluoride copolymers, sugar monomer copolymers and / or homopolymers, acrylic monomer copolymers and / or homopolymers, styrene monomer copolymers and / or homopolymers, butadiene monomer copolymers and / or homopolymers, phenolic monomer copolymers and / or homopolymers, aldehyde monomer copolymers and / or homopolymers, diamine monomer copolymers and / or homopolymers, dianhydride monomer copolymers and / or homopolymers, benzene ring monomer copolymers and / or homopolymers, or their derivatives and modifiers.

20. An electrical appliance, characterized in that: The sodium metal battery includes any one of claims 1 to 14 or any one of claims 15 to 19 prepared by the method thereof.

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