A sodium ion solid-state battery and its preparation method

Abstract

The present invention relates to a sodium ion solid-state battery and a preparation method thereof, belonging to the technical field of sodium ion solid-state batteries. The sodium ion solid-state battery provided by the present invention comprises a positive electrode layer, a solid electrolyte membrane, and a negative electrode layer in sequence; the components of the solid electrolyte membrane include a specific halide solid electrolyte and a polymer, and the halide solid electrolyte is Na 2+2x MO 1+x (BF4) y X 4‑y , M is selected from Zr, Hf, Ti, and Mo, X is selected from F, Cl, Br, and I, and x and y satisfy 0≤x≤1.0 and 0≤y≤1.0. The solid-state battery of the present invention uses a halide solid electrolyte with high room temperature ionic conductivity in combination with a specific polymer to form a membrane instead of a traditional separator. This significantly reduces separator shrinkage at high temperatures, further improves battery safety, and maintains excellent cycle performance, offering broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion solid-state batteries, and in particular to a sodium ion solid-state battery and a preparation method thereof. Background Art

[0002] With the rapid development of the global economy, climate change and environmental issues are becoming increasingly prominent, and it is becoming increasingly urgent to replace traditional fossil energy with clean energy. Secondary battery technology, as a key energy storage and conversion technology, plays a decisive role in energy conservation and emission reduction. The full electrification of modern transportation has placed higher requirements on the energy density, safety and cycle life of secondary batteries. Currently, lithium-ion batteries dominate many markets due to their high energy density and steadily declining costs. However, in order to completely solve the range anxiety and safety risks of electric vehicles and support the development of large electric vehicles such as electric heavy trucks and electric aircraft, the ideal next-generation high-energy density battery must have higher energy density and safety, as well as a cycle life that can support long-term service. All-solid-state batteries are considered a key technology to meet these requirements due to their non-flammability, high energy density potential and environmental adaptability.

[0003] Halide solid electrolytes exhibit high room temperature ionic conductivity, typically greater than 10 -3 S / cm, a property comparable to that of sulfide solid electrolytes and far higher than that of oxide solid electrolytes. Furthermore, it has a wide electrochemical stability window, making it compatible with high-voltage cathode materials and thus improving the energy density of the battery. Furthermore, halide solid electrolytes have high chemical stability and good stability to air and moisture, making them less prone to decomposition during synthesis, storage, and transportation, thereby reducing operational complexity and cost. They also have good mechanical deformability and can be tightly bonded to electrode materials through a simple cold-pressing process, thereby improving the interfacial stability and overall performance of the battery. However, halide solid electrolytes still face shortcomings in their applications. Their sensitivity to humid environments limits their stability in practical applications, and they easily absorb moisture, leading to performance degradation. Interfacial instability between halide solid electrolytes and metal anodes (such as lithium and sodium metal) is also a significant issue, which can lead to capacity decay and increased safety risks during battery cycling.

[0004] Therefore, it is of great practical significance to develop a sodium ion solid-state battery that can achieve high ionic conductivity, excellent cycle performance and battery safety. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of the prior art and provide a sodium ion solid-state battery and a method for preparing the same. The sodium ion solid-state battery provided by the present invention has excellent cycle capacity retention, and the solid electrolyte membrane has high strength, good high-temperature shrinkage resistance, high safety, and high application value.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention provides a sodium ion solid-state battery, characterized in that it comprises a positive electrode layer, a solid electrolyte membrane, and a negative electrode layer in sequence;

[0008] The components of the solid electrolyte membrane include a halide solid electrolyte, a polymer and a plasticizer;

[0009] The components of the positive electrode layer and / or the negative electrode layer include a halide solid electrolyte;

[0010] The halide solid electrolyte is Na 2+2x MO 1+x (BF4) y X 4-y , M is at least one of Zr, Hf, Ti, and Mo, X is at least one of F, Cl, Br, and I, and x and y satisfy 0≤x≤1.0, 0≤y≤1.0;

[0011] The polymer is at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, polyethylene oxide, styrene-butadiene rubber, nitrile rubber, polyacrylic acid, sodium alginate, polyacrylonitrile, polyvinyl pyrrolidone, polyurethane, polyacrylate, polystyrene, polymethyl methacrylate, and polyimide.

[0012] The present invention adopts a specific solid electrolyte membrane in the solid-state battery, and adopts a specific halide solid electrolyte Na in the solid electrolyte membrane, the positive electrode layer and / or the negative electrode layer. 2+2x MO 1+x (BF4) y X 4-y , providing a high energy density, high safety solid-state battery. Among them, the solid electrolyte membrane is generally arranged between alternating positive and negative electrode layers.

[0013] The halide solid electrolyte in the solid electrolyte membrane of the present invention has a relatively high room temperature conductivity, and due to BF4 - Doping stabilizes its structure and improves stability in humid air. Combined with specific polymers and plasticizers, it can comprehensively enhance the strength and stability of the solid electrolyte membrane in solid-state batteries, achieving a tensile strength exceeding 9.9 MPa and a shrinkage rate of less than 0.5% under high-temperature treatment, ensuring excellent safety. Using other sodium ion halide electrolytes or other polymers can significantly reduce the strength of the solid electrolyte membrane.

[0014] In addition, the present invention uses the above-mentioned halide solid electrolyte in the positive electrode layer and / or negative electrode layer of the solid-state battery, which can further improve the battery's cycle capacity retention rate and improve the battery's cycle stability; in addition, the halide solid electrolyte in the positive electrode layer and / or negative electrode layer also helps to further improve the battery's mechanical strength and improve battery safety.

[0015] The sodium-ion solid-state battery provided by the present invention adopts a specific solid-state electrolyte membrane, which has better safety and good performance: the battery's 20th cycle capacity retention rate is above 96.7%, and the 50th cycle capacity retention rate is above 94%, which has certain application prospects.

[0016] Preferably, the preparation method of the halide solid electrolyte is a mechanochemical method.

[0017] Preferably, in the halide solid electrolyte, x and y satisfy 0.25≤x≤1.0, 0.3≤y≤0.4.

[0018] As a preferred method of the present invention, the halide solid electrolyte includes Na 2.5 ZrO 1.25 (BF4) 0.3 Cl 3.7 、Na 2.75 ZrO 1.375 (BF4) 0.3 Cl 3.7 、Na4ZrO2(BF4) 0.3 Cl 3.7 、Na3ZrO 1.5 (BF4) 0.4 Cl 3.6 It should be noted that the selection of the halide solid electrolyte of the present invention is not limited to the specific ones mentioned above. Those skilled in the art can adjust or replace the constituent elements and doping ratios of the halide solid electrolyte within the limited range of the solid-state battery of the present invention according to actual needs.

[0019] Preferably, in the solid electrolyte membrane, the mass ratio of the halide solid electrolyte, polymer and plasticizer is halide solid electrolyte:polymer:plasticizer=(70-90):(5-25):(5-15).

[0020] Further preferably, in the solid electrolyte membrane, the mass ratio of the halide solid electrolyte, polymer and plasticizer is halide solid electrolyte:polymer:plasticizer=(80-90):(5-15):(5-10).

[0021] Under the optimal solid electrolyte membrane ratio, the strength and ionic conductivity of the membrane can be better taken into account.

[0022] Preferably, in the solid electrolyte membrane, the plasticizer is at least one of di(2-ethylhexyl) phthalate, dioctyl oxalate, tricresyl phosphate, tolylene diphenyl phosphate, and propylene glycol oxalate.

[0023] Preferably, the solid electrolyte membrane is prepared by mixing the halide solid electrolyte, polymer and plasticizer under a protective atmosphere, heating and melting, and hot pressing to obtain the solid electrolyte membrane.

[0024] Further preferably, the protective atmosphere is an inert atmosphere, and the heating and melting temperature is 25-200°C.

[0025] Preferably, the components of the positive electrode layer include a positive electrode active material, a positive electrode conductor, a binder and a halide solid electrolyte; the components of the negative electrode layer include a negative electrode active material, a negative electrode conductor, a binder and a halide solid electrolyte.

[0026] Further preferably, in the positive electrode layer, the positive electrode active material is at least one of a sodium ion oxide positive electrode material, a sodium ion polyanion positive electrode material, and a sodium ion Prussian blue positive electrode material; and the positive electrode conductive agent is at least one of Super P, VGCF, CNT, and graphene.

[0027] Further preferably, in the negative electrode layer, the negative electrode active material is at least one of metallic sodium, carbon material, silicon-carbon material, and sodium titanate; and the negative electrode conductive agent is at least one of carbon black, VGCF, CNT, and graphene.

[0028] More preferably, the binder is at least one of polyvinylidene fluoride, polytetrafluoroethylene, styrene-butadiene rubber, polyacrylic acid, sodium carboxymethyl cellulose, and sodium alginate.

[0029] In a second aspect, the present invention provides a method for preparing the above-mentioned sodium ion solid-state battery, comprising the following steps:

[0030] (1) A positive electrode active material, a positive electrode conductive agent, a binder and a halide solid electrolyte are mixed, extruded and rolled to prepare a positive electrode layer; a negative electrode active material, a negative electrode conductive agent, a binder and a halide solid electrolyte are mixed, extruded and rolled to prepare a negative electrode layer;

[0031] (2) hot rolling the solid electrolyte membrane onto the surface of the positive electrode layer and the negative electrode layer to obtain a positive electrode sheet and a negative electrode sheet;

[0032] (3) Assembling the positive electrode sheets and the negative electrode sheets into a battery cell by stacking them in an alternating positive and negative manner, and performing a charging and formation treatment to obtain the sodium ion solid-state battery.

[0033] The sodium ion solid-state battery prepared by the preparation method of the present invention has good cycle stability, high safety and relatively low cost.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention improves the solid electrolyte membrane in the solid-state battery and optimizes the selection of suitable halide solid electrolytes and polymers in the solid-state battery structure to achieve higher tensile strength and better anti-shrinkage performance of the solid electrolyte membrane in the sodium ion solid-state battery, thereby improving the safety of the solid-state battery while taking into account the excellent cycle capacity retention rate. It has high application value in the research and development and application of all-solid-state batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the basic structure of the sodium ion solid-state battery provided by the present invention. DETAILED DESCRIPTION

[0037] To better illustrate the objectives, technical solutions, and advantages of the present invention, the present invention will be further described below with reference to specific examples. The experimental methods used in the following examples are conventional methods unless otherwise specified; the materials and reagents used are commercially available unless otherwise specified.

[0038] Example 1

[0039] An embodiment of a sodium ion solid-state battery of the present invention, wherein the preparation method of the sodium ion solid-state battery of this embodiment comprises the following steps:

[0040] (1) Sodium tetrafluoroborate, zirconium chloride, and sodium oxide were mixed uniformly at a molar ratio of 0.3:1:1.25 under protective gas, and then ball milled for 4 h at a ball-to-material ratio of 50:1. The halide solid electrolyte Na was obtained by sieving. 2.5 ZrO 1.25 (BF4) 0.3 Cl 3.7 ;

[0041] (2) Sodium iron pyrophosphate was selected as the positive electrode active material, Super P was used as the positive electrode conductive agent, PVDF was used as the binder, and the halide solid electrolyte was prepared in a mass ratio of 92:1.5:1.5:5, and the positive electrode layer of the solid-state battery was obtained after mixing, extrusion, and rolling;

[0042] The negative electrode layer of the solid-state battery was obtained by mixing hard carbon as the negative electrode active material, Super P as the negative electrode conductive agent, sodium carboxymethyl cellulose and styrene-butadiene rubber (mass ratio of 1:1) as the binder, and the halide solid electrolyte in the ratio of 91:1:3:5.

[0043] (3) The halide solid electrolyte, polytetrafluoroethylene (PTFE) as a polymer, and di(2-ethylhexyl) phthalate as a plasticizer were stirred in an inert atmosphere at a mass ratio of 90:5:5 for 6 h, and then heated to melt at 120° C., and then hot-pressed to obtain a solid electrolyte membrane;

[0044] (4) The solid electrolyte membrane of step 2 is uniformly heated and rolled onto the surface of the positive electrode layer to obtain a positive electrode sheet, and the solid electrolyte of step 2 is uniformly heated and rolled onto the surface of the negative electrode layer to obtain a negative electrode sheet, ready for use in the next process;

[0045] (5) The positive and negative electrode sheets prepared in step 3 are assembled into a battery cell by alternating positive and negative stacking, and charged and formed at 80°C to obtain the sodium ion solid-state battery. The basic structural diagram is shown in FIG. Figure 1 .

[0046] Example 2

[0047] The only difference between Example 2 and Example 1 is that the mass ratio of solid electrolyte:PTFE:di(2-ethylhexyl)phthalate in the preparation of the solid electrolyte membrane is 80:10:10.

[0048] Example 3

[0049] The only difference between Example 3 and Example 1 is that the mass ratio of solid electrolyte:PTFE:di(2-ethylhexyl)phthalate in the preparation of the solid electrolyte membrane is 80:15:5.

[0050] Example 4

[0051] The only difference between Example 4 and Example 1 is that the mass ratio of solid electrolyte:PTFE:di(2-ethylhexyl)phthalate in the preparation of the solid electrolyte membrane is 70:25:5.

[0052] Example 5

[0053] The only difference between Example 5 and Example 1 is that the mass ratio of solid electrolyte:PTFE:di(2-ethylhexyl)phthalate in the preparation of the solid electrolyte membrane is 70:20:10.

[0054] Example 6

[0055] The only difference between Example 6 and Example 1 is that the mass ratio of solid electrolyte:PTFE:di(2-ethylhexyl)phthalate in the preparation of the solid electrolyte membrane is 70:15:15.

[0056] Example 7

[0057] An embodiment of a sodium ion solid-state battery of the present invention, wherein the preparation method of the sodium ion solid-state battery of this embodiment comprises the following steps:

[0058] (1) Sodium tetrafluoroborate, zirconium chloride, and sodium oxide were mixed uniformly at a molar ratio of 0.3:1:1.375 under protective gas, and then ball milled for 4 h at a ball-to-material ratio of 50:1. The halide solid electrolyte Na was obtained by sieving. 2.75 ZrO 1.375 (BF4) 0.3 Cl 3.7 ;

[0059] (2) Sodium iron pyrophosphate was selected as the positive electrode active material, Super P was used as the positive electrode conductive agent, PVDF was used as the binder, and the halide solid electrolyte was prepared in a mass ratio of 92:1.5:1.5:5, and the positive electrode layer of the solid-state battery was obtained after mixing, extrusion, and rolling;

[0060] The negative electrode layer of the solid-state battery was obtained by mixing hard carbon as the negative electrode active material, Super P as the negative electrode conductive agent, sodium carboxymethyl cellulose and styrene-butadiene rubber (mass ratio of 1:1) as the binder, and the halide solid electrolyte in the ratio of 91:1:3:5.

[0061] (3) The halide solid electrolyte, PTFE as a polymer, and di(2-ethylhexyl) phthalate as a plasticizer were stirred in an inert atmosphere at a mass ratio of 80:10:10 for 6 h, and then heated to melt at 120° C., and then hot-pressed to obtain a solid electrolyte membrane;

[0062] (4) The solid electrolyte membrane of step 2 is uniformly heated and rolled onto the surface of the positive electrode layer to obtain a positive electrode sheet, and the solid electrolyte of step 2 is uniformly heated and rolled onto the surface of the negative electrode layer to obtain a negative electrode sheet, ready for use in the next process;

[0063] (5) The positive and negative electrode sheets prepared in step 3 are assembled into a battery cell in an alternating positive and negative stacking manner, and a charging and formation treatment is performed at 80° C. to obtain the sodium ion solid-state battery.

[0064] Example 8

[0065] The only difference between Example 8 and Example 7 is that in step (1), sodium tetrafluoroborate, zirconium chloride, and sodium oxide are prepared in a molar ratio of 0.3:1:2 to obtain a halide solid electrolyte Na4ZrO2(BF4). 0.3 Cl 3.7 .

[0066] Example 9

[0067] The only difference between Example 9 and Example 7 is that in step (1), sodium tetrafluoroborate, zirconium chloride, and sodium oxide are prepared in a molar ratio of 0.4:1:1.5 to obtain a halide solid electrolyte Na3ZrO 1.5 (BF4) 0.4 Cl 3.6 .

[0068] Example 10

[0069] The only difference between Example 10 and Example 7 is that sodium nickel manganate Na is used in step (2). 0.67 Ni 0.33 Mn 0.67 O2 as positive electrode material, Super P as positive electrode conductive agent, PVDF as binder, Na 2.75 ZrO 1.375 (BF4) 0.3 Cl 3.7 As a solid electrolyte, the positive electrode layer of the positive solid-state battery is made by mixing, extruding and rolling in a mass ratio of 92:1.5:1.5:5.

[0070] Example 11

[0071] The only difference between Example 11 and Example 7 is that in step (2), metallic sodium is used as the negative electrode layer.

[0072] Example 12

[0073] The only difference between Example 12 and Example 7 is that in step (3), polyvinylidene fluoride (PVDF) is used as the polymer for the solid electrolyte membrane.

[0074] Comparative Example 1

[0075] A battery, the preparation method is as follows:

[0076] (1) Sodium iron pyrophosphate was selected as the positive electrode active material, Super P was used as the conductive agent, and PVDF was used as the binder. The mixture was stirred in a mass ratio of 97:1.5:1.5 with NMP as the solvent to obtain a positive electrode slurry. The positive electrode slurry was coated on the surface of aluminum foil, and then rolled after drying to obtain the positive electrode layer of the battery;

[0077] Hard carbon is selected as the negative electrode active material, Super P is used as the conductive agent, and sodium carboxymethyl cellulose and styrene-butadiene rubber (mass ratio is 1:1) are used as the binder. The negative electrode slurry is obtained by stirring with water as the solvent in a mass ratio of 96:1:3. The negative electrode slurry is coated on the surface of the copper foil, and after drying, it is rolled to obtain the negative electrode layer of the battery;

[0078] (2) Polypropylene was selected as the diaphragm, 1 mol / L NaPF6 was selected as the electrolyte solute, and EC:DEC=1:1 was selected as the electrolyte solvent to prepare the sodium ion battery electrolyte; the positive and negative electrodes were alternately stacked, the sodium ion battery electrolyte was injected, and the battery was assembled into a cell, and the battery was charged and formed at 80°C to obtain a battery.

[0079] Comparative Example 2

[0080] The only difference between Comparative Example 2 and Example 7 is that in step (1), sodium tetrafluoroborate, lanthanum chloride, and sodium oxide are prepared in a molar ratio of 0.3:1:1.375 to prepare the solid electrolyte Na 2.75 LaO 1.375 (BF4) 0.3 Cl 2.7 .

[0081] Comparative Example 3

[0082] The only difference between Comparative Example 3 and Example 7 is that in step (3), sodium carboxymethyl cellulose is used as the polymer for the solid electrolyte membrane.

[0083] Comparative Example 4

[0084] The only difference between Comparative Example 4 and Example 7 is that in step (1), sodium tetrahydroborate, zirconium chloride, and sodium oxide are prepared in a molar ratio of 0.3:1:1.375 to obtain a solid electrolyte Na 2.75 ZrO 1.375 (BH4) 0.3 Cl 3.7 .

[0085] Effect Example 1

[0086] In order to explore the effect of the ratio of the solid electrolyte membrane in the sodium ion solid-state battery provided by the present invention on the performance, the solid electrolyte membranes prepared in step (3) of Examples 1-6 and Comparative Examples 2-4 were subjected to the following tests:

[0087] 1. Electrochemical impedance spectroscopy to calculate ionic conductivity;

[0088] 2. Tensile strength test, refer to GB / T 1040;

[0089] 3. The solid electrolyte membrane was exposed to 90°C for 2 h and 105°C for 1 h, and its volume shrinkage at high temperature was recorded. A 25 μm microporous single-layer Celgard 2400 membrane was used as a control. The results are shown in Table 1.

[0090] As shown in Table 1, in Examples 1-6, within the range of components and ratios of the solid electrolyte membrane of the present invention, the excellent high-temperature volume shrinkage resistance and tensile strength of the solid electrolyte membrane can be taken into account. The volume shrinkage rate under different high-temperature treatments is low and significantly higher than that of ordinary commercially available membranes, and the tensile strength is above 9.9 MPa, which comprehensively improves the strength of the solid electrolyte membrane and helps to improve battery safety. However, the mass ratios of different components in the solid electrolyte membrane significantly affect the ionic conductivity, among which the ionic conductivity is higher under the ratio of halide solid electrolyte, polymer and plasticizer in Example 2. In contrast, in Comparative Example 3, the polymer is outside the specified range of the present invention, and Comparative Examples 2 and 4 use solid electrolytes outside the specified range. Although a certain ionic conductivity can be achieved, the tensile strength of the solid electrolyte membrane is reduced to varying degrees, which may significantly affect the mechanical strength of the membrane.

[0091] Table 1 Performance results of solid electrolyte membranes of Examples and Comparative Examples

[0092]

[0093]

[0094] Effect Example 2

[0095] To further explore the cycle performance of the sodium ion solid-state battery provided by the present invention, the following tests were conducted on the batteries in Example 2, Examples 7-12, and Comparative Examples 1-3:

[0096] At room temperature, the battery was subjected to constant current charge and discharge tests using the Wuhan Blue Power CT2001A test system. The test voltage range was 2.0-4.1 V, and the capacity retention rates at the 20th and 50th cycles were recorded. The results are shown in Table 2.

[0097] As shown in Table 2, comparing Examples 2, 7-9 and Comparative Examples 1-3, the halide solid electrolyte and polymer components defined in the present invention are used in the examples, and the battery cycle capacity retention rate is relatively high, with the battery capacity retention rate at the 20th cycle being above 96.7% and the capacity retention rate at the 50th cycle being above 94.1%. The battery of conventional diaphragm + electrolyte used in Comparative Example 1 has a low capacity retention rate at the 50th cycle, and the safety performance of the liquid battery is poor. Comparative Examples 2 and 3 respectively use halide solid electrolytes and polymers other than those defined in the present invention, and the capacity retention rate is significantly reduced and the stability is poor. In addition, from the comparison of Example 7 with Examples 10 and 11, it can be seen that the selection of components of the positive electrode layer and the negative electrode layer within the scope defined in the present invention also has a certain impact on the performance of the battery.

[0098] From the above, it can be seen that the technical solution of the present invention achieves higher tensile strength of the solid electrolyte membrane in the sodium ion solid-state battery and better anti-shrinkage performance at high temperature by optimizing the selection of suitable halide solid electrolytes and polymers in the solid-state battery structure, thereby improving the safety of the solid-state battery while taking into account the excellent cycle capacity retention rate, and has high application value in the research and development and application of all-solid-state batteries.

[0099] Table 2 Performance test results of sodium ion batteries

[0100]

[0101]

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A sodium ion solid-state battery, characterized in that: It includes a positive electrode layer, a solid electrolyte membrane, and a negative electrode layer in sequence; The components of the solid electrolyte membrane include a halide solid electrolyte, a polymer and a plasticizer; The components of the positive electrode layer and / or the negative electrode layer include a halide solid electrolyte; The halide solid electrolyte is Na 2+2x MO 1+x (BF4) y X 4-y , M is at least one of Zr, Hf, Ti, and Mo, X is at least one of F, Cl, Br, and I, and x and y satisfy 0≤x≤1.0, 0≤y≤1.0; The polymer is at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, polyethylene oxide, styrene-butadiene rubber, nitrile rubber, polyacrylic acid, sodium alginate, polyacrylonitrile, polyvinyl pyrrolidone, polyurethane, polyacrylate, polystyrene, polymethyl methacrylate, and polyimide.

2. The sodium ion solid-state battery according to claim 1, wherein In the halide solid electrolyte, x and y satisfy 0.25≤x≤1.0, 0.3≤y≤0.

4.

3. The sodium ion solid-state battery according to claim 1, wherein In the solid electrolyte membrane, the mass ratio of the halide solid electrolyte, polymer and plasticizer is halide solid electrolyte:polymer:plasticizer=(70-90):(5-25):(5-15).

4. The sodium ion solid-state battery according to claim 1, wherein In the solid electrolyte membrane, the plasticizer is at least one of di(2-ethylhexyl) phthalate, dioctyl oxalate, tricresyl phosphate, tolyl diphenyl phosphate, and propylene glycol oxalate.

5. The sodium ion solid-state battery according to claim 1, wherein The preparation method of the solid electrolyte membrane comprises: uniformly mixing the halide solid electrolyte, polymer and plasticizer under a protective atmosphere, heating and melting, and hot pressing to obtain the solid electrolyte membrane.

6. The sodium ion solid-state battery according to claim 1, wherein The components of the positive electrode layer include a positive electrode active material, a positive electrode conductor, a binder and a halide solid electrolyte; the components of the negative electrode layer include a negative electrode active material, a negative electrode conductor, a binder and a halide solid electrolyte.

7. The sodium ion solid-state battery according to claim 6, characterized in that In the positive electrode layer, the positive electrode active material is at least one of a sodium ion oxide positive electrode material, a sodium ion polyanion positive electrode material, and a sodium ion Prussian blue positive electrode material; and the positive electrode conductive agent is at least one of Super P, VGCF, CNT, and graphene.

8. The sodium ion solid-state battery according to claim 6, wherein: In the negative electrode layer, the negative electrode active material is at least one of metallic sodium, carbon material, silicon-carbon material, and sodium titanate; and the negative electrode conductive agent is at least one of carbon black, VGCF, CNT, and graphene.

9. The sodium ion solid-state battery according to claim 6, characterized in that The binder is at least one of polyvinylidene fluoride, polytetrafluoroethylene, styrene-butadiene rubber, polyacrylic acid, sodium carboxymethyl cellulose and sodium alginate.

10. The method for preparing a sodium ion solid-state battery according to any one of claims 6 to 9, wherein: The following steps are involved: (1) A positive electrode active material, a positive electrode conductive agent, a binder and a halide solid electrolyte are mixed, extruded and rolled to prepare a positive electrode layer; a negative electrode active material, a negative electrode conductive agent, a binder and a halide solid electrolyte are mixed, extruded and rolled to prepare a negative electrode layer; (2) hot rolling the solid electrolyte membrane onto the surface of the positive electrode layer and the negative electrode layer to obtain a positive electrode sheet and a negative electrode sheet; (3) Assembling the positive electrode sheets and the negative electrode sheets into a battery cell by stacking them in an alternating positive and negative manner, and performing a charging and formation treatment to obtain the sodium ion solid-state battery.

Images