An asymmetric functional sodium battery separator, a preparation method and application thereof

Abstract

The application discloses an asymmetric functional sodium battery diaphragm and a preparation method and application thereof, and belongs to the technical field of sodium batteries, and the structure comprises a base film and a negative electrode sodium supplementing / semiconductor mixed layer coated on one side surface of the base film; or the structure comprises a base film, a negative electrode sodium supplementing layer and a semiconductor coating layer, the negative electrode sodium supplementing layer and the semiconductor coating layer are arranged on two side surfaces of the base film respectively, or the negative electrode sodium supplementing layer and the semiconductor coating layer are arranged on the same side surface of the base film to form a laminated structure; components of the negative electrode sodium supplementing / semiconductor mixed layer comprise sodium supplementing material, semiconductor material, conductive agent and auxiliary agent; components of the negative electrode sodium supplementing layer comprise sodium supplementing material, conductive agent and auxiliary agent; and components of the semiconductor coating layer comprise semiconductor material, conductive agent and auxiliary agent. The asymmetric functional sodium battery diaphragm is easy to prepare, can enhance the fast charging characteristics of a sodium ion battery, supplement sodium to improve the first charging and discharging efficiency and capacity, and enhance the safety characteristics such as overcharge resistance, overheat resistance and thermal runaway resistance.

Description

Technical Field

[0001] This invention relates to the field of sodium battery technology, specifically to an asymmetric functional sodium battery separator, its preparation method, and its application. Background Technology

[0002] Sodium batteries are secondary batteries that use sodium ions as charge carriers. They boast high theoretical energy density, abundant raw material resources, relatively high safety, low cost, and good environmental adaptability, making them a hot research topic in the new energy field. The separator is a crucial component of a sodium battery, located between the positive and negative electrodes. It provides a channel for sodium ion transport, and the physicochemical properties of the separator affect the electrochemical performance and safety of the sodium battery.

[0003] To improve the capacity of sodium-ion batteries, existing technologies typically coat the positive or negative electrode side of the separator with a functional coating. Chinese patent document CN117352954A discloses a sodium-supplemented electrolyte separator. The preparation method includes: dissolving a polymer matrix in a solvent to obtain a polymer gel; dispersing a sodium-supplementing agent in the polymer gel and heating and mixing to obtain a doped gel; removing the solvent from the doped gel to obtain a polymer film; and activating the polymer film in a sodium-ion electrolyte to obtain a gel-state sodium-supplemented electrolyte separator. This sodium-supplemented electrolyte separator offers better safety than liquid electrolytes and can alleviate sodium battery gas generation to some extent. Chinese patent document CN116526066A discloses a sodium battery separator coating comprising a core-shell structure of conductive material coating solid electrolyte particles, with the solid electrolyte forming the core and the conductive material forming the shell; the solid electrolyte core is selected from β-Al₂O₃ and Na₂O. 1+x Zr2Si x P 3-x O 12 At least one of (0≤x≤3) is used, and the conductive material layer is a binary composite material of carbon and aluminum-doped zinc oxide. This invention simultaneously introduces sodium ion conductivity and electronic conductivity into the separator material, reducing ion migration resistance during sodium battery cycling and improving battery formation efficiency. The sodium-containing compound or mixture used in the above patent is coated on at least one side of the separator, and its function is to provide an additional source of sodium ions, improve sodium ion conductivity, and enhance the sodium replenishment effect.

[0004] Semiconductor materials possess specific band gaps and band widths, along with high critical magnetic fields and high electron saturation velocities. Under certain conditions, they exhibit high electron migration rates, thus possessing characteristics such as resistance to high temperatures, high power, high voltage, high frequency, and high radiation. These characteristics are highly compatible with the requirements of battery cells for high temperature resistance, high voltage resistance, and high rate capability, making them of great potential application value in the field of rechargeable batteries. To improve the electrochemical performance and safety of sodium batteries, it is necessary to develop a functional sodium battery separator in conjunction with semiconductor materials. Summary of the Invention

[0005] This invention provides an asymmetric functional sodium battery separator with a simple structure, easy preparation, and readily available raw materials. It can enhance the fast charging characteristics of sodium-ion batteries, improve the first charge and discharge efficiency and capacity by replenishing sodium, and enhance safety characteristics such as resistance to overcharge, overheating, and thermal runaway.

[0006] The specific technical solution adopted is as follows:

[0007] An asymmetric functional sodium battery separator,

[0008] The structure includes a base film and a negative electrode sodium-semiconductor hybrid layer coated on one side of the base film;

[0009] Alternatively, the structure may include a base film, a negative electrode sodium replenishment layer, and a semiconductor coating, with the negative electrode sodium replenishment layer and the semiconductor coating respectively disposed on both sides of the base film, or the negative electrode sodium replenishment layer and the semiconductor coating both disposed on the same side of the base film, forming a stacked structure.

[0010] The thickness of the base film is 5 μm to 35 μm;

[0011] The thickness of the negative electrode sodium-supplementing / semiconductor hybrid layer is 0.5 μm to 19 μm, and the components include sodium-supplementing material, semiconductor material, conductive agent and additives;

[0012] The thickness of the negative electrode sodium replenishment layer is 0.5μm to 10μm, and the components include sodium replenishment material, conductive agent and additives;

[0013] The thickness of the semiconductor coating is 0.2 μm to 20 μm, and the components include semiconductor materials, conductive agents, and additives.

[0014] In the asymmetric functional sodium battery separator of the present invention, the sodium replenishing material disposed on the negative electrode side of the separator has sodium conduction characteristics. At the same time, the sodium replenishing material can store sodium to provide extra space for sodium ion charging, thereby improving the utilization efficiency of sodium ions and thus improving the initial efficiency, capacity and energy density of the cell. During the cycling process, the sodium replenishing material with sodium storage function can slowly release sodium ions, thereby achieving a good sodium replenishment effect on the negative electrode side, thus improving the cycle performance. Introducing semiconductor materials can improve the heat resistance and pressure resistance of the separator and ensure the safety of use.

[0015] Preferably, in the asymmetric functional sodium battery separator, the thickness of the base film is 9 μm to 12 μm; the thickness of the negative electrode sodium supplement / semiconductor hybrid layer is 4 μm to 15 μm; the thickness of the negative electrode sodium supplement layer is 3 μm to 6 μm; and the thickness of the semiconductor coating is 1 μm to 5 μm.

[0016] Coating a sodium replenishment layer or a sodium replenishment / semiconductor hybrid layer on the negative electrode side of the separator can not only accept sodium from the positive electrode and have certain sodium storage characteristics and overcharge resistance, but also provide an additional sodium source to reasonably replenish sodium and improve the first charge and discharge efficiency, while also having certain safety performance.

[0017] Preferably, the asymmetric functional sodium battery separator includes a base film, a negative electrode sodium replenishment layer, and a semiconductor coating. The negative electrode sodium replenishment layer and the semiconductor coating are respectively disposed on the negative electrode side and the positive electrode side surface of the base film. The asymmetric functional coating is applied to both sides of the separator. The positive electrode side of the separator is coated with a semiconductor coating, and the negative electrode side is coated with a negative electrode sodium replenishment layer. The negative electrode sodium replenishment layer and the semiconductor coating work synergistically to enhance the fast-charging characteristics of the sodium-ion battery, improve the initial charge-discharge efficiency and capacity through sodium replenishment, and enhance safety characteristics such as resistance to overcharge, overheating, and thermal runaway.

[0018] The base film material includes, but is not limited to, at least one of polypropylene (PP), polyethylene (PE), polypropylene / polyethylene composite (PP / PE), polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), polyphenylene sulfide (PPS), polyimide (PI), aramid, glass fiber (CF), and lignin fiber.

[0019] Optionally, the sodium-supplementing material is selected from Na2Ti3O7, NaTi3O6OH, Na 0.66 [Li 0.22 Ti 0.78 O2, Li4Ti5O 12 NaTi2(PO4)3, Na 1.4 Al 0.4 Ti 1.6 At least one of (PO4)3. The Dv50 particle size of the sodium-supplementing material is 100 nm-5 μm, and more specifically 350 nm-5.5 μm.

[0020] Optionally, the semiconductor material is selected from at least one of Si, GaAs, InP, SiC, GaN, ZnO, diamond, and AlN.

[0021] The conductive agent is selected from at least one of conductive graphite, fiber conductive agent, or sheet conductive agent; conductive graphite includes carbon black SP, acetylene black AB, or Ketjen black KB; fiber conductive agent includes vapor-grown carbon fiber VGCF or carbon nanotubes CNTs; sheet conductive agent includes graphene GN.

[0022] Preferably, in the negative electrode sodium-supplementing / semiconductor hybrid layer, based on the total mass of sodium-supplementing material, semiconductor material, conductive agent and additives as 100%, the content of sodium-supplementing material is 5% to 30%, the content of semiconductor material is 7% to 40%, the content of conductive agent is 1% to 5%, and the additives include binders and dispersants, with the content of binders being 3% to 5% and the content of dispersants being 25% to 55%.

[0023] Preferably, in the negative electrode sodium replenishment layer, based on the total mass of the sodium replenishment material, conductive agent, and additives as 100%, the content of the sodium replenishment material is 82% to 95%, the content of the conductive agent is 1% to 5%, and the additives include binders and dispersants, with the binder content being 3.5% to 10% and the dispersant content being 0.5% to 3%; the content of the conductive agent is less than or equal to the content of the binder.

[0024] Preferably, in the semiconductor coating, based on the total mass of semiconductor material, conductive agent and additives as 100%, the content of semiconductor material is 87% to 97.5%, the content of conductive agent is 0.5% to 2%, and the additives include binder and dispersant, with the content of binder being 1% to 8% and the content of dispersant being 1% to 3%.

[0025] The present invention also provides a method for preparing the aforementioned asymmetric functional sodium battery separator, comprising the following steps:

[0026] S10 Dissolve the binder, dispersant, and conductive agent in an oily solvent to obtain a first mixture; dissolve the sodium-supplementing material and dispersant in an oily solvent to obtain a second mixture; thoroughly mix the first and second mixtures to obtain a sodium-supplementing slurry; dissolve the semiconductor material, conductive agent, binder, and dispersant in water to obtain a semiconductor material slurry;

[0027] S11 Dissolve the binder, dispersant, and conductive agent in an oily solvent to obtain a third mixture. Dissolve the sodium-supplementing material, semiconductor material, and dispersant in an oily solvent to obtain a fourth mixture. After thoroughly mixing the third and fourth mixtures, a sodium-supplementing slurry containing semiconductor material is obtained.

[0028] S2. The sodium-supplementing slurry, semiconductor material slurry, or sodium-supplementing slurry containing semiconductor material in S10 is coated onto the base film to obtain the asymmetric functional sodium battery separator.

[0029] Preferably, the oily solvent includes at least one of N-methylpyrrolidone, ethanol, acetone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0030] Preferably, the dispersant includes at least one of sodium carboxymethyl cellulose, sodium hexametaphosphate, sodium alginate, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and disodium ethylenediaminetetraacetate (EDTA).

[0031] Preferably, the adhesive is selected from at least one of polymethyl methacrylate styrene-butadiene rubber, polyvinylidene fluoride, polystyrene-acrylic emulsion, polyvinyl alcohol, ethylene vinyl acetate copolymer, polytetrafluoroethylene, polyvinyl acetate, polyurethane, polyvinylidene fluoride hexafluoropropylene copolymer, polyacrylic acid, and polyacrylate.

[0032] Preferably, the solid content in the sodium-supplementing slurry is 45wt% to 70wt%, the solid content in the semiconductor material slurry is 30wt% to 50wt%, and the solid content in the sodium-supplementing slurry containing semiconductor material is 45wt% to 75wt%.

[0033] The present invention also provides a sodium-ion battery, wherein the sodium-ion battery includes the aforementioned asymmetric functional sodium battery separator.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] This invention, through the design of an asymmetric functional sodium battery separator, can not only provide reasonable sodium replenishment and improve overcharge resistance, but also enhance the separator's high temperature and high pressure resistance, thus building a safety barrier for the separator and thereby improving the cell's energy density and enhancing cell safety. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of the asymmetric functional sodium battery separator in Example 1.

[0037] Figure 2 This is a schematic diagram of the structure of the asymmetric functional sodium battery separator in Example 2.

[0038] Figure 3 This is a schematic diagram of the structure of the asymmetric functional sodium battery separator in Example 3.

[0039] Figure 4 This is a schematic diagram of the structure of the asymmetric functional sodium battery separator in Example 4.

[0040] Figure 5 This is a schematic diagram of the initial formation curve of the sodium-ion battery cell made with the diaphragm in Comparative Example 1.

[0041] Figure 6 This is a schematic diagram of the initial formation curve of the sodium-ion battery cell made from the asymmetric functional sodium battery separator in Example 4. Detailed Implementation

[0042] To make the objectives, features, and advantages of this invention more apparent and understandable, a detailed description is provided below through specific embodiments. Many specific details are set forth in the following description to provide a thorough understanding of the invention. However, the invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below. Technical features in various embodiments of the invention can be combined appropriately without mutual conflict.

[0043] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer. Contents not described in detail in this specification are prior art known to those skilled in the art. Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0044] Example 1

[0045] 22 kg of polyvinylidene fluoride, 3 kg of sodium carboxymethyl cellulose, and 10 kg of conductive carbon black were thoroughly mixed in 150 kg of N-methylpyrrolidone to form a conductive adhesive solution; 200 kg of sodium-supplementing material Li4Ti5O2 was added. 12 (Dv50 particle size is 350nm) and 0.2 kg sodium alginate are mixed evenly in 100 kg N-methylpyrrolidone to form a suspension; conductive adhesive is added to the suspension and then sand-milled and thoroughly stirred to obtain sodium-added slurry;

[0046] 91.5 kg of Si, 0.5 kg of conductive carbon black SP, 5 kg of binder (the mass ratio of polyacrylic acid PPA to SBR is 1:4), and 3 kg of dispersant sodium carboxymethyl cellulose were stirred and dispersed evenly in 100 kg of solvent H2O to obtain a semiconductor material slurry.

[0047] Sodium-supplementing slurry is coated on one side of the base film, dried, and then rolled up for later use to form a negative electrode sodium-supplementing layer. Then, a semiconductor material slurry is coated on the other side of the base film to form a semiconductor coating, thus obtaining the asymmetric functional sodium battery separator.

[0048] like Figure 1 As shown, the asymmetric functional sodium battery separator includes a base film, a semiconductor coating on the positive electrode side, and a sodium-supplementing layer on the negative electrode side; the base film is a PE separator with a thickness of 9 μm, the sodium-supplementing layer has a thickness of 5 μm, and the semiconductor coating has a thickness of 3 μm.

[0049] Example 2

[0050] 23 kg of polyvinylidene fluoride, 3 kg of sodium carboxymethyl cellulose, and 10 kg of conductive carbon black were thoroughly mixed in 200 kg of N-methylpyrrolidone to form a conductive adhesive solution. 200 kg of sodium-supplementing material Na2Ti3O7 (Dv50 particle size of 550 nm) and 0.2 kg of sodium alginate were thoroughly mixed in 85 kg of N-methylpyrrolidone to form a suspension. The conductive adhesive solution was added to the suspension, and after sand milling and thorough mixing, a sodium-supplementing slurry was obtained.

[0051] 91.5 kg of diamond C, 0.5 kg of conductive carbon black SP, 5 kg of binder (the mass ratio of polyacrylic acid PPA to SBR is 1:4), and 3 kg of dispersant carboxymethyl cellulose CMC were stirred and dispersed evenly in 200 kg of solvent H2O to obtain a semiconductor material slurry.

[0052] Sodium-supplementing slurry is coated on one side of the base film, dried, and then rolled up for later use to form a negative electrode sodium-supplementing layer. A semiconductor material slurry is then coated on the negative electrode sodium-supplementing layer to form a semiconductor coating, thus obtaining the asymmetric functional sodium battery separator.

[0053] like Figure 2 As shown, the asymmetric functional sodium battery separator includes a base film, a negative electrode sodium replenishment layer, and a semiconductor coating on the negative electrode side; the base film is a PE separator with a thickness of 12 μm, the negative electrode sodium replenishment layer has a thickness of 5 μm, and the semiconductor coating has a thickness of 3 μm.

[0054] Example 3

[0055] 23 kg of polyvinylidene fluoride, 3 kg of sodium carboxymethyl cellulose, and 10 kg of conductive carbon black were thoroughly mixed in 200 kg of N-methylpyrrolidone to form a conductive adhesive solution. 200 kg of sodium-supplementing material NaTi2(PO4)3 (Dv50 particle size of 350 nm) and 0.2 kg of sodium alginate were thoroughly mixed in 80 kg of N-methylpyrrolidone to form a suspension. The conductive adhesive solution was added to the suspension, and after sand milling and thorough mixing, a sodium-supplementing slurry was obtained.

[0056] 91.5 kg of AlN, 0.5 kg of conductive carbon black SP, 5 kg of binder (the mass ratio of polyacrylic acid PPA to SBR is 1:4), and 3 kg of dispersant carboxymethyl cellulose CMC were stirred and dispersed evenly in 200 kg of solvent H2O to obtain a semiconductor material slurry.

[0057] A semiconductor material slurry is coated onto one side of the base film to form a semiconductor coating. A sodium-supplementing slurry is then coated onto the semiconductor coating to form a negative electrode sodium-supplementing layer, thus obtaining the asymmetric functional sodium battery separator.

[0058] like Figure 3 As shown, the asymmetric functional sodium battery separator includes a base film, a semiconductor coating on the negative electrode side, and a sodium replenishment layer on the negative electrode side; the base film is a PE separator with a thickness of 9 μm, the semiconductor coating has a thickness of 3 μm, and the sodium replenishment layer on the negative electrode has a thickness of 5 μm.

[0059] Example 4

[0060] 3 kg of polyvinylidene fluoride, 18 kg of sodium carboxymethyl cellulose, and 2 kg of conductive carbon black were thoroughly mixed in 40 kg of N-methylpyrrolidone to form a conductive adhesive solution; 18 kg of sodium supplement material Na... 0.66 [Li 0.22 Ti 0.78 O2 (Dv50 particle size of 5.5 μm), 25 kg of semiconductor material ZnO, and 0.2 kg of sodium alginate were mixed evenly in 40 kg of N-methylpyrrolidone to form a suspension; conductive adhesive was added to the suspension and then sand-milled and thoroughly stirred to obtain a sodium-supplemented slurry containing semiconductor material.

[0061] A sodium-supplementing slurry containing semiconductor materials is coated onto one side of the base film to form a negative electrode sodium-supplementing / semiconductor hybrid layer, thus obtaining the asymmetric functional sodium battery separator.

[0062] like Figure 4 As shown, the asymmetric functional sodium battery separator includes a base film and a negative electrode sodium supplement / semiconductor hybrid layer on the negative electrode side; the base film is a PE separator with a thickness of 12μm, and the negative electrode sodium supplement / semiconductor hybrid layer has a thickness of 10μm.

[0063] Comparative Example 1

[0064] Comparative Example 1 is a commercially available membrane product consisting of 9 (PE base film, 9 μm thick) + 3 (single-layer alumina ceramic layer, 3 μm thick) + 3 (PVDF coating, 3 μm thick) + 3 (PVDF coating, 3 μm thick), with a total thickness of 18 μm.

[0065] Comparative Example 2

[0066] Comparative Example 2 is a commercially available diaphragm product consisting of 12 (PP base film, 12 μm thick) + 3 (single-layer alumina ceramic layer, 3 μm thick) + 3 (PVDF coating, 3 μm thick) + 3 (PVDF coating, 3 μm thick), with a total thickness of 21 μm.

[0067] Comparative Example 3

[0068] Comparative Example 3 is a commercially available 20 (PP base film, 20 μm thick) + 3 (single-layer alumina ceramic layer, 3 μm thick) separator product, with a total thickness of 24 μm.

[0069] Sample Analysis

[0070] Test method description: The thickness of the diaphragm is tested according to GB / T36363—2018 6.4; the heat shrinkage rate is tested according to GB / T36363—2018 6.5.2; the puncture strength is tested according to GB / T36363—2018 6.5.3.

[0071] The initial charge / discharge efficiency needs to be improved by manufacturing a sodium-ion battery cell, in which the positive electrode material is NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 (Xiangying XN33S), negative electrode material is hard carbon (BTR BSHC360); electrolyte is 1 mol / L NaPF6+EC:DEC=1:1+5%FEC+1.5%VC+0.5%DDT+0.5%MSDS; the separator is the same as in the examples or comparative examples. The separator-negative electrode-separator-positive electrode-separator are stacked to form a core, and then the positive and negative electrode tabs are welded out and laser-sealed in an aluminum shell. The dry cell is baked at 90℃ for 18h and then cooled and injected with electrolyte. After injection, the cell is left to stand for 24h for formation (the formation is done in a stepped manner, i.e., 0.05C charging to 2.8V, 0.1C charging to 3.0V, 0.2C charging to 3.2V, and the charging capacity C1 is recorded at this time). After formation, the cell is injected with electrolyte again. The same electrolyte is used for both injections (95% for the first injection and 5% for the second injection) and then laser-sealed.

[0072] The battery cell was charged to 4.0V at 0.2C, and the charging capacity at this point was recorded as C2. After resting for 30 minutes, the battery cell was discharged to 0V at 0.2C, and the discharge capacity at this point was recorded as C3. The initial efficiency is then calculated as C3 / (C1+C2). Comparing the initial efficiencies of the example and the comparative example, it can be seen that using the asymmetric functional sodium battery separator improves the initial efficiency by 4.5%~6.8% compared to the comparative example (in Example 4). Figure 6 Compared with Comparative Example 1 Figure 5 Compared to the first-line efficacy, it is improved by 6.8%, and its resistance to heat shrinkage and puncture strength at 130℃ is also significantly improved, as shown in Table 1.

[0073] Table 1. Diaphragm performance test results in the examples and comparative examples.

[0074]

[0075] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An asymmetric functional sodium battery separator, characterized in that, The structure includes a base film and a negative electrode sodium-semiconductor hybrid layer coated on one side of the base film; Alternatively, the structure may include a base film, a negative electrode sodium replenishment layer, and a semiconductor coating, with the negative electrode sodium replenishment layer and the semiconductor coating respectively disposed on both sides of the base film, or the negative electrode sodium replenishment layer and the semiconductor coating both disposed on the same side of the base film, forming a stacked structure. The thickness of the base film is 5 μm to 35 μm; The thickness of the negative electrode sodium-supplementing / semiconductor hybrid layer is 0.5 μm to 19 μm, and the components include sodium-supplementing material, semiconductor material, conductive agent and additives; The thickness of the negative electrode sodium replenishment layer is 0.5μm to 10μm, and the components include sodium replenishment material, conductive agent and additives; The thickness of the semiconductor coating is 0.2 μm to 20 μm, and the components include semiconductor materials, conductive agents, and additives. The sodium-supplementing material is Li4Ti5O 12 ; The semiconductor material is selected from at least one of Si, GaAs, InP, SiC, GaN, diamond, and AlN; The conductive agent is selected from at least one of conductive graphite, carbon black SP, acetylene black AB, Ketjen black KB, vapor-grown carbon fiber VGCF, carbon nanotubes CNTs, and graphene GN.

2. The asymmetric functional sodium battery separator according to claim 1, characterized in that, The asymmetric functional sodium battery separator includes a base film, a negative electrode sodium replenishment layer, and a semiconductor coating, with the negative electrode sodium replenishment layer and the semiconductor coating respectively disposed on the negative electrode side and the positive electrode side surface of the base film.

3. The asymmetric functional sodium battery separator according to claim 1, characterized in that, The base film material includes at least one of polypropylene, polyethylene, polyethylene terephthalate, polyvinylidene fluoride, polyphenylene sulfide, polyimide, aramid, glass fiber, and lignin fiber.

4. The asymmetric functional sodium battery separator according to claim 1, characterized in that, In the aforementioned negative electrode sodium-supplementing / semiconductor hybrid layer, based on the total mass of the sodium-supplementing material, semiconductor material, conductive agent, and additives as 100%, the content of the sodium-supplementing material is 5%–30%, the content of the semiconductor material is 7%–40%, the content of the conductive agent is 1%–5%, and the additives include binders and dispersants, with the binder content being 3%–5% and the dispersant content being 25%–55%. And / or, in the negative electrode sodium replenishment layer, based on the total mass of the sodium replenishment material, conductive agent, and additives as 100%, the content of the sodium replenishment material is 82% to 95%, the content of the conductive agent is 1% to 5%, and the additives include binders and dispersants, with the binder content being 3.5% to 10% and the dispersant content being 0.5% to 3%; the content of the conductive agent is ≤ the content of the binder; And / or, in the semiconductor coating, based on the total mass of semiconductor material, conductive agent and additives as 100%, the content of semiconductor material is 87% to 97.5%, the content of conductive agent is 0.5% to 2%, and the additives include binder and dispersant, with the content of binder being 1% to 8% and the content of dispersant being 1% to 3%.

5. The method for preparing the asymmetric functional sodium battery separator according to any one of claims 1-4, characterized in that, Includes the following steps: S10 Dissolve the binder, dispersant, and conductive agent in an oily solvent to obtain a first mixture; dissolve the sodium-supplementing material and dispersant in an oily solvent to obtain a second mixture; thoroughly mix the first and second mixtures to obtain a sodium-supplementing slurry; dissolve the semiconductor material, conductive agent, binder, and dispersant in water to obtain a semiconductor material slurry; S11 Dissolve the binder, dispersant, and conductive agent in an oily solvent to obtain a third mixture. Dissolve the sodium-supplementing material, semiconductor material, and dispersant in an oily solvent to obtain a fourth mixture. After thoroughly mixing the third and fourth mixtures, a sodium-supplementing slurry containing semiconductor material is obtained. S2. The sodium-supplementing slurry, semiconductor material slurry, or sodium-supplementing slurry containing semiconductor material in S10 is coated onto the base film to obtain the asymmetric functional sodium battery separator.

6. The method for preparing the asymmetric functional sodium battery separator according to claim 5, characterized in that, The solid content in sodium-supplementing slurry is 45wt% to 70wt%, the solid content in semiconductor material slurry is 30wt% to 50wt%, and the solid content in sodium-supplementing slurry containing semiconductor materials is 45wt% to 75wt%.

7. A sodium-ion battery, characterized in that, Includes the asymmetric functional sodium battery separator as described in any one of claims 1-4.

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