A composite solid-state electrolyte and a solid-state sodium metal battery and a preparation method thereof

Abstract

The application provides a composite solid-state electrolyte and a solid-state sodium metal battery and a preparation method thereof, and belongs to the field of solid-state sodium metal batteries. The preparation method of the composite solid-state electrolyte comprises the following steps: spin coating a precursor liquid on the surface of a solid-state electrolyte and drying to obtain a composite solid-state electrolyte; the precursor liquid comprises a bismuth-containing precursor liquid and / or an antimony-containing precursor liquid; the preparation method of the bismuth-containing precursor liquid / antimony-containing precursor liquid comprises the following steps: mixing a mixed solution of bismuth chloride / antimony chloride and an organic solvent with water to perform a hydrolysis reaction, so as to obtain the bismuth-containing precursor liquid / antimony-containing precursor liquid. The solid-state sodium metal battery prepared from the composite solid-state electrolyte prepared by the preparation method has good electrochemical performance and cycle stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of solid-state sodium metal batteries, in particular to a composite solid-state electrolyte and a solid-state sodium metal battery and a preparation method thereof. BACKGROUND

[0002] With the rapid depletion of global lithium battery raw materials, the development of non-lithium batteries for energy storage systems is becoming increasingly important for establishing a sustainable energy use pattern. Sodium batteries have become a very viable alternative to lithium batteries due to their similar chemical and physical properties to lithium, abundant reserves and low cost.

[0003] When the battery uses a conventional organic liquid as an electrolyte, the metal sodium anode, like the lithium anode, also encounters problems such as uneven deposition / delamination and dendrite penetration, which in turn causes short circuits, potential safety problems such as burning, etc.

[0004] Replacing the electrolyte with a solid-state electrolyte can fundamentally solve the safety problem of the battery. However, due to the fact that the commonly used NASICON solid-state electrolyte will generate Na2CO3 and NaOH on the surface under storage conditions, which is sodium-repellent, deteriorates the interface wettability, causes poor solid-solid contact at the electrolyte / negative electrode interface, hinders the transport of sodium ions at the interface, and causes the internal resistance of the all-solid-state sodium ion battery to increase sharply, and the cycle performance of the battery to deteriorate. SUMMARY

[0005] The purpose of the present application is to provide a composite solid-state electrolyte and a solid-state sodium metal battery and a preparation method thereof. The composite solid-state electrolyte prepared by the preparation method provided by the present application can improve the interface wettability between the solid-state electrolyte and the metal sodium negative electrode, so that the solid-state sodium metal battery has good electrochemical performance and cycle stability.

[0006] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0007] The present application provides a preparation method of a composite solid-state electrolyte, comprising:

[0008] drying the precursor liquid coated on the surface of the solid-state electrolyte to obtain a composite solid-state electrolyte;

[0009] The precursor liquid includes a bismuth-containing precursor liquid and / or an antimony-containing precursor liquid;

[0010] The preparation method of the bismuth-containing precursor liquid / antimony-containing precursor liquid comprises:

[0011] Mixing the mixture of bismuth chloride / antimony chloride and organic solvent with water to carry out a hydrolysis reaction to obtain a bismuth-containing precursor liquid / antimony-containing precursor liquid.

[0012] Preferably, the ratio of the amount of bismuth chloride / antimony chloride in the mixture to the volume of the organic solvent is (0.1-1) mol: 1 L.

[0013] Preferably, the molar ratio of bismuth chloride / antimony chloride to water is (0.1-1) mol: (1.7-13.5) mL.

[0014] Preferably, the pH value of the hydrolysis reaction of the bismuth chloride and organic solvent mixture with water is 6.5 to 7.5.

[0015] Preferably, the pH value of the mixture of antimony chloride and organic solvent and water for hydrolysis reaction is 0 to 1.

[0016] Preferably, the coating method is spin coating, and the number of spin coatings is 1 to 3 times, with drying performed after each spin coating.

[0017] Preferably, the volume of the precursor fluid for each spin coating is 20–50 μL / cm³. 2 .

[0018] The present invention also provides a composite solid electrolyte prepared by the preparation method described above, comprising a solid electrolyte and a precursor layer on the surface of the solid electrolyte.

[0019] This invention also provides a method for preparing a solid-state sodium metal battery, comprising:

[0020] The first composite is obtained by heat-treating a precursor layer on the surface of a solid electrolyte with metallic sodium.

[0021] The first composite is assembled with the positive electrode to obtain a solid sodium metal battery.

[0022] The present invention also provides a solid sodium metal battery prepared by the preparation method described above, comprising a sodium metal anode, an interface layer, a composite solid electrolyte, and a cathode arranged sequentially.

[0023] This invention provides a method for preparing a composite solid electrolyte, comprising: spin-coating a precursor liquid onto the surface of a solid electrolyte and then drying it to obtain a composite solid electrolyte; the precursor liquid includes a bismuth-containing precursor liquid and / or an antimony-containing precursor liquid; the method for preparing the bismuth-containing precursor liquid / antimony-containing precursor liquid includes: mixing a mixture of bismuth chloride / antimony chloride and an organic solvent with water to carry out a hydrolysis reaction to obtain the bismuth-containing precursor liquid / antimony-containing precursor liquid. This invention involves coating a precursor liquid onto the surface of a solid electrolyte. Hydrochloric acid obtained from the hydrolysis of bismuth chloride or antimony chloride reacts with Na₂CO₃ and NaOH on the solid electrolyte surface to generate NaCl. NaCl provides a rapid ion diffusion channel and prevents electrons from entering the electrolyte, thus inhibiting dendrite growth. A solid sodium metal battery is prepared using a composite solid electrolyte. BiOCl and / or SbOCl, formed from the hydrolysis of bismuth chloride and / or antimony chloride contained in the composite solid electrolyte, contact the sodium metal anode to generate Na₃OCl and Na₃Bi and / or Na₃Sb alloys. Na₃OCl provides a rapid ion diffusion channel and prevents electrons from entering the electrolyte, inhibiting dendrite growth. The Na₃Bi and / or Na₃Sb alloys not only increase interfacial contact but also guide a uniform electric field distribution, regulate the uniform deposition of metallic Na, and improve the electrochemical performance and cycle stability of the solid sodium metal battery. The results of the examples show that the solid sodium metal battery prepared using the composite solid electrolyte provided by this invention has an internal resistance of 48–74 Ω / cm. 2 Sodium-symmetric cells at 0.3 mA·cm -2 At a current density of 1900–2200 hours, the solid sodium metal battery can cycle up to 300 times at 0.5C with a capacity retention of 97.6%, exhibiting excellent electrochemical performance and cycle stability. Attached Figure Description

[0024] Figure 1 A macroscopic photograph of the molten sodium spreading on the surface of the solid electrolyte prepared in Comparative Example 1 of this invention;

[0025] Figure 2 This is a macroscopic photograph of molten sodium spreading on the surface of the composite solid electrolyte prepared in Example 1 of the present invention;

[0026] Figure 3 Here is a cross-sectional SEM image of the first composite material prepared in Comparative Application Example 1 of this invention;

[0027] Figure 4 Here is a cross-sectional SEM image of the first composite material prepared in Application Example 1 of this invention;

[0028] Figure 5 Impedance spectrum of solid sodium metal battery in Comparative Application Example 1 of the present invention;

[0029] Figure 6 The impedance spectrum of the solid sodium metal battery in Application Example 1 of this invention;

[0030] Figure 7 To compare the sodium symmetric battery prepared with the solid electrolyte (NZSP electrolyte sheet) in Example 1 of this invention, the constant current (0.1 mA·cm⁻¹) is... -2 ) Cyclic curve graph;

[0031] Figure 8 The constant current (0.3 mA·cm) of the sodium symmetric battery prepared by the composite solid electrolyte in Example 1 of this invention is used to measure the current. -2 ) Cyclic curve graph;

[0032] Figure 9 The graph shows the cycle performance of the solid sodium metal battery in Application Example 1 of this invention at 0.5C. Detailed Implementation

[0033] This invention provides a method for preparing a composite solid electrolyte, comprising:

[0034] The precursor liquid is coated onto the surface of the solid electrolyte and then dried to obtain the composite solid electrolyte.

[0035] In this invention, the precursor fluid includes a bismuth-containing precursor fluid and / or an antimony-containing precursor fluid.

[0036] In this invention, when the precursor liquid comprises a bismuth-containing precursor liquid and an antimony-containing precursor liquid, it is preferable to mix the bismuth-containing precursor liquid and the antimony-containing precursor liquid to obtain the precursor liquid, and then perform coating. In this invention, the volume ratio of the bismuth-containing precursor liquid to the antimony-containing precursor liquid is preferably 1:1.

[0037] In this invention, the preparation method of the bismuth-containing precursor liquid / antimony-containing precursor liquid includes:

[0038] A mixture of bismuth chloride / antimony chloride and an organic solvent is mixed with water and subjected to a hydrolysis reaction to obtain a bismuth-containing precursor solution / antimony-containing precursor solution.

[0039] In one embodiment of the present invention, the ratio of the amount of bismuth chloride / antimony chloride in the mixture to the volume of the organic solvent can be (0.1-1) mol:1 L, (0.1-0.5) mol:1 L, or (0.1-0.3) mol:1 L. The present invention does not specifically limit the type of organic solvent; any organic solvent commonly used by those skilled in the art that can dissolve bismuth chloride / antimony chloride is acceptable. In an embodiment of the present invention, the organic solvent can be isopropanol. Limiting the ratio of the amount of bismuth chloride / antimony chloride to the volume of the organic solvent to the above-mentioned range is beneficial for spin-coating the precursor.

[0040] In one embodiment of the present invention, the molar ratio of bismuth chloride / antimony chloride to water volume can be (0.1–1) mol:(1.7–13.5) mL, (0.1–0.5) mol:(4–10) mL, or (0.1–0.3) mol:(6–8) mL. Limiting the molar ratio of bismuth chloride / antimony chloride to water volume within the above ranges promotes the hydrolysis of bismuth chloride / antimony chloride.

[0041] In one embodiment of the present invention, the pH value of the hydrolysis reaction of the bismuth chloride and organic solvent mixture with water can be 6.5–7.5, or even 7. In another embodiment of the present invention, the pH adjuster used to adjust the pH value of the hydrolysis reaction can be ammonia; the present invention does not have specific limitations on the amount and concentration of ammonia added, as long as the pH can be adjusted to 6.5–7.5. Adjusting the pH of the bismuth chloride hydrolysis reaction to neutral in the present invention yields BiOCl precipitate.

[0042] In one embodiment of the present invention, the pH value of the mixture of antimony chloride and organic solvent mixed with water for hydrolysis reaction can be 0-1, or even 0.5. In another embodiment of the present invention, the pH adjuster used to adjust the pH value of the hydrolysis reaction can be a hydrochloric acid solution; the present invention does not have specific limitations on the amount and concentration of the hydrochloric acid solution added, as long as it can adjust the pH value of the hydrolysis reaction to 0-1. Adjusting the pH value of the antimony chloride hydrolysis reaction to 0-1 in the present invention yields SbOCl precipitate.

[0043] In one embodiment of the present invention, the mixing time can be 30 minutes; the mixing method can be stirring; and the stirring speed can be 600–1000 rpm. By limiting the stirring speed to the above range, the present invention ensures that bismuth chloride / antimony chloride undergoes sufficient hydrolysis.

[0044] In this invention, taking antimony chloride as an example, the equation for the hydrolysis reaction is shown in Equation 1:

[0045] SbCl3 + H2O → SbOCl↓ + 2HCl (Equation 1)

[0046] In one embodiment of the present invention, the coating method can be spin coating; the number of spin coatings can be 1 to 3 times, or even 2 times; the rotation speed of each spin coating can be 800 to 2000 rpm, or even 1200 to 1600 rpm; the volume of the precursor fluid in each spin coating can be 20 to 50 μL / cm³. 2 The concentration can also be 30–40 μL / cm 2Both can be 35 μL / cm 2 By limiting the number of spin coatings, the rotation speed of each spin coating, and the volume of precursor liquid in each spin coating to the range described above, a precursor layer of suitable thickness can be obtained.

[0047] Preferably, drying is performed after each spin coating step; the drying is vacuum drying; as one embodiment of the invention, the vacuum drying temperature can be 60–120°C, 80–100°C, or 90°C; the vacuum drying time can be 12–24 h, 16–20 h, or 18 h. By limiting the drying method, temperature, and time to the above ranges, the invention removes excess solvent and allows the hydrolysis products (HCl) in the precursor liquid on the solid electrolyte surface to react with Na₂CO₃ / NaOH that may be present on the solid electrolyte surface to generate NaCl. NaCl provides a rapid ion diffusion channel and prevents electrons from entering the electrolyte, thus inhibiting dendrite growth.

[0048] In this invention, the solid electrolyte is a NASICON-type solid electrolyte; as one embodiment of this invention, the solid electrolyte can be an NZSP solid electrolyte.

[0049] In an embodiment of the present invention, the preparation method of the NZSP solid electrolyte is as follows:

[0050] 1) According to Na3Zr2Si2PO 12 The chemical formula of (NZSP) solid electrolyte is given by measuring the powders of Na2CO3, ZrO2, SiO2 and NH4H2PO4 separately, mixing them to obtain a precursor mixture; the stoichiometric ratio of Na2CO3 and NH4H2PO4 is 1.1 times the theoretical value.

[0051] 2) The precursor mixture obtained in step 1) is wet ball-milled with anhydrous ethanol as the medium, and then dried and calcined once to obtain solid electrolyte pre-calcined powder; the calcination temperature is 1000℃ and the calcination time is 12h.

[0052] 3) The solid electrolyte pre-calcined powder obtained in step 2) is wet ball-milled with anhydrous ethanol as a medium and then dried to obtain solid electrolyte powder.

[0053] 4) Pass the solid electrolyte powder obtained in step 3) through a 200-mesh sieve, press the sieved powder into a blank under a pressure of 250 MPa, sinter it at 1230°C for 12 hours, cool it, and then perform surface grinding and polishing to obtain NZSP solid electrolyte.

[0054] The present invention also provides a composite solid electrolyte prepared by the preparation method described above, wherein the composite solid electrolyte comprises a solid electrolyte and a precursor layer on the surface of the solid electrolyte.

[0055] In one embodiment of the present invention, the thickness of the precursor layer on the surface of the solid electrolyte can be 1 to 5 μm.

[0056] This invention also provides a method for preparing a solid-state sodium metal battery, comprising:

[0057] The first composite is obtained by heat-treating a precursor layer on the surface of a solid electrolyte with metallic sodium.

[0058] The first composite is assembled with the positive electrode to obtain a solid sodium metal battery.

[0059] In one embodiment of the present invention, the heat treatment temperature can be 100–140°C, 110–130°C, or 120°C; the heat treatment time can be 25–35 min, or 30 min. The present invention enables the BiOCl and / or SbOCl contained in the precursor layer on the surface of the solid electrolyte to react with molten sodium to generate Na3OCl and Na3Bi and / or Na3Sb alloys, thereby improving the electrochemical performance and cycle stability of the solid sodium metal battery.

[0060] In this invention, the contact between the metallic sodium and the precursor layer on the surface of the composite solid electrolyte allows the BiOCl and / or SbOCl contained in the precursor layer to contact the metallic sodium anode to generate Na3OCl and Na3Bi and / or Na3Sb alloys (forming an interface layer). Na3OCl can provide a fast ion diffusion channel and prevent electrons from entering the electrolyte, thus inhibiting dendrite growth. The Na3Bi and / or Na3Sb alloys can not only increase the interface contact but also guide the uniform distribution of the electric field, regulate the uniform deposition of metallic Na, and improve the electrochemical performance and cycle stability of the solid sodium metal battery.

[0061] The present invention also provides a solid sodium metal battery prepared by the preparation method described above, comprising a sodium metal anode, an interface layer, a composite solid electrolyte, and a cathode arranged sequentially.

[0062] In one embodiment of the present invention, the positive electrode may include an aluminum current collector and a positive electrode active material layer coated on the surface of the aluminum current collector; the areal density of the positive electrode active material layer coated on the surface of the aluminum current collector may be 2 mg / cm³. 2 The positive electrode active material layer comprises 65 wt% sodium vanadium phosphate, 15 wt% NZSP powder, 10 wt% conductive carbon, and 10 wt% PVDF.

[0063] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0064] Example 1

[0065] A method for preparing a composite solid electrolyte is as follows:

[0066] The precursor solution was spin-coated onto the surface of a solid electrolyte (NZSP electrolyte tablets were left to stand at room temperature for ten days before use). After each spin-coating, the electrolyte was vacuum-dried at 100°C for 12 hours to obtain a composite solid electrolyte. The spin-coating was performed twice. The spin speed for each spin-coating was 1600 rpm. The volume of the precursor solution in each spin-coating was 40 μL / cm³. 2 ;

[0067] The precursor fluid is an antimony-containing precursor fluid;

[0068] The method for preparing the antimony-containing precursor fluid:

[0069] SbCl3 was mixed with isopropanol to form a 0.1 mol / L solution, and then water was added. The pH value was adjusted to 0 using hydrochloric acid solution (0.1 mol / L). The mixture was stirred at 800 rpm for 30 min to carry out the hydrolysis reaction and obtain an antimony-containing precursor liquid. The molar ratio of SbCl3 to water was 0.1 mol: 5 mL.

[0070] The preparation method of the solid electrolyte (NZSP electrolyte sheet) is as follows:

[0071] 1) According to Na3Zr2Si2PO 12 The chemical formula of (NZSP) solid electrolyte is given by measuring the powders of Na2CO3, ZrO2, SiO2 and NH4H2PO4 separately, mixing them to obtain a precursor mixture; the stoichiometric ratio of Na2CO3 and NH4H2PO4 is 1.1 times the theoretical value.

[0072] 2) The precursor mixture obtained in step 1) is wet ball-milled with anhydrous ethanol as the medium, and then dried and calcined once to obtain solid electrolyte pre-calcined powder; the calcination temperature is 1000℃ and the calcination time is 12h.

[0073] 3) The solid electrolyte pre-calcined powder obtained in step 2) is wet ball-milled with anhydrous ethanol as a medium and then dried to obtain solid electrolyte powder.

[0074] 4) Pass the solid electrolyte powder obtained in step 3) through a 200-mesh sieve, press the sieved powder into a blank under a pressure of 250 MPa, sinter it at 1230°C for 12 hours, cool it, and then perform surface grinding and polishing to obtain NZSP solid electrolyte sheet.

[0075] The composite solid electrolyte prepared by the method consists of a solid electrolyte and a precursor layer on the surface of the solid electrolyte; the thickness of the precursor layer on the surface of the solid electrolyte is 2 μm.

[0076] Example 2

[0077] A method for preparing a composite solid electrolyte is as follows:

[0078] The precursor solution was spin-coated onto the surface of a solid electrolyte (NZSP electrolyte tablets were left to stand at room temperature for ten days before use). After each spin-coating, the electrolyte was vacuum-dried at 80°C for 24 hours to obtain a composite solid electrolyte. The spin-coating was performed three times. The spin speed for each spin-coating was 2000 rpm. The volume of the precursor solution for each spin-coating was 20 μL / cm³. 2 ;

[0079] The precursor fluid is a bismuth-containing precursor fluid;

[0080] The method for preparing the bismuth-containing precursor fluid:

[0081] BiCl3 was mixed with isopropanol to form a 0.1 mol / L solution, and then water was added. The pH value was adjusted to 7 using ammonia (0.1 mol / L). The mixture was stirred at 600 rpm for 30 min to carry out the hydrolysis reaction and obtain the precursor fluid. The molar ratio of BiCl3 to water was 0.5 mol: 10 mL.

[0082] The preparation method of the solid electrolyte (NZSP electrolyte sheet) is the same as in Example 1.

[0083] The composite solid electrolyte prepared by the method consists of a solid electrolyte and a precursor layer on the surface of the solid electrolyte; the thickness of the precursor layer on the surface of the solid electrolyte is 3 μm.

[0084] Example 3

[0085] A method for preparing a composite solid electrolyte is as follows:

[0086] The precursor solution was spin-coated onto the surface of a solid electrolyte (NZSP electrolyte tablets were left to stand at room temperature for ten days before use). After each spin-coating, the electrolyte was vacuum-dried at 110°C for 12 hours to obtain a composite solid electrolyte. The spin-coating was performed once. The spin speed for each spin-coating was 1000 rpm. The volume of the precursor solution in each spin-coating was 30 μL / cm³.2 ;

[0087] The precursor fluid is an antimony-containing precursor fluid and a bismuth-containing precursor fluid;

[0088] The preparation methods of the antimony-containing precursor liquid and the bismuth-containing precursor liquid are as follows:

[0089] SbCl3 was mixed with isopropanol to form a 0.1 mol / L solution, and then water was added. The pH value was adjusted to 0 using hydrochloric acid solution (0.1 mol / L). The mixture was stirred at 800 rpm for 30 min to carry out the hydrolysis reaction and obtain an antimony-containing precursor liquid. The molar ratio of SbCl3 to water was 0.1 mol: 5 mL.

[0090] BiCl3 was mixed with isopropanol to form a 0.1 mol / L solution, and then water was added. The pH value was adjusted to 7 using ammonia (0.1 mol / L). The mixture was stirred at 600 rpm for 30 min to carry out the hydrolysis reaction and obtain a bismuth-containing precursor liquid. The molar ratio of BiCl3 to water was 0.5 mol: 10 mL.

[0091] The antimony-containing precursor liquid and the bismuth-containing precursor liquid are mixed at a volume ratio of 1:1 to obtain the antimony-containing precursor liquid and the bismuth-containing precursor liquid.

[0092] The preparation method of the solid electrolyte (NZSP electrolyte sheet) is the same as in Example 1.

[0093] The composite solid electrolyte prepared by the method consists of a solid electrolyte and a precursor layer on the surface of the solid electrolyte; the thickness of the precursor layer on the surface of the solid electrolyte is 1.6 μm.

[0094] Comparative Example 1

[0095] A method for preparing a composite solid electrolyte is as follows:

[0096] The precursor solution was spin-coated onto the surface of a solid electrolyte (NZSP electrolyte tablets were left to stand at room temperature for ten days before use). After each spin-coating, the electrolyte was vacuum-dried at 80°C for 12 hours to obtain a composite solid electrolyte. The spin-coating was performed three times. The spin speed for each spin-coating was 2000 rpm. The volume of the precursor solution in each spin-coating was 20 μL / cm³. 2 ;

[0097] The method for preparing the precursor fluid:

[0098] BiOCl was mixed with isopropanol and stirred at 800 rpm for 30 min to obtain a 0.1 mol / L precursor solution.

[0099] The preparation method of the solid electrolyte (NZSP electrolyte sheet) is the same as in Example 1.

[0100] The composite solid electrolyte prepared by the method consists of a solid electrolyte and a precursor layer on the surface of the solid electrolyte; the thickness of the precursor layer on the surface of the solid electrolyte is 2.2 μm.

[0101] Application Example 1

[0102] A method for preparing a solid-state sodium metal battery:

[0103] Sodium metal was placed on the precursor layer on the surface of the composite solid electrolyte prepared in Example 1 and heat-treated at 100°C for 30 min to obtain the first composite.

[0104] The first composite is assembled with the positive electrode to obtain a solid sodium metal battery;

[0105] The solid sodium metal battery prepared by the method described herein consists of a sodium metal anode, an interface layer, a composite solid electrolyte, and a cathode arranged sequentially.

[0106] The positive electrode is an aluminum current collector and a positive electrode active material layer coated on the surface of the aluminum current collector; the areal density of the positive electrode active material layer coated on the surface of the aluminum current collector is 2 mg / cm³. 2 The positive electrode active material layer is composed of 65 wt% sodium vanadium phosphate, 15 wt% NZSP powder, 10 wt% conductive carbon and 10 wt% PVDF.

[0107] Application Example 2

[0108] The difference between Application Example 2 and Application Example 1 is only that in the preparation method of the solid sodium metal battery, metallic sodium is placed on the precursor layer on the surface of the composite solid electrolyte prepared in Example 2 and heat-treated at 120°C for 30 minutes to obtain the first composite. Otherwise, it is the same as Application Example 1.

[0109] Application Example 3

[0110] The difference between Application Example 3 and Application Example 1 is only that in the preparation method of the solid sodium metal battery, metallic sodium is placed on the precursor layer on the surface of the composite solid electrolyte prepared in Example 3 and heat-treated at 120°C for 30 minutes to obtain the first composite. Otherwise, it is the same as Application Example 1.

[0111] Comparative Application Example 1

[0112] A method for preparing a solid-state sodium metal battery:

[0113] The sodium metal anode was placed on a solid electrolyte (NZSP electrolyte sheet) and heat-treated at 120°C for 30 min to obtain the first composite.

[0114] The first composite is assembled with the positive electrode to obtain a solid sodium metal battery;

[0115] The solid sodium metal battery prepared by the method described herein consists of a sodium metal anode, an interface layer, a solid electrolyte (NZSP electrolyte sheet), and a positive electrode arranged sequentially.

[0116] The positive electrode is an aluminum current collector and a positive electrode active material layer coated on the surface of the aluminum current collector; the areal density of the positive electrode active material layer coated on the surface of the aluminum current collector is 2 mg / cm³. 2 The positive electrode active material layer is composed of 65 wt% sodium vanadium phosphate, 15 wt% NZSP powder, 10 wt% conductive carbon and 10 wt% PVDF.

[0117] Comparative Application Example 2

[0118] The only difference between Comparative Example 2 and Comparative Example 2 is that in the preparation method of the solid sodium metal battery, metallic sodium is placed on the precursor layer on the surface of the composite solid electrolyte prepared in Comparative Example 1 and heat-treated at 120°C for 30 min to obtain the first composite. The rest is the same as in Comparative Example 2.

[0119] The solid electrolyte surfaces prepared in Comparative Example 1 and the composite solid electrolyte surfaces prepared in Example 1 were brought into contact with molten sodium. The wettability of metallic sodium with the solid electrolyte and the composite solid electrolyte was observed. A macroscopic photograph of the molten sodium spreading on the solid electrolyte surface prepared in Comparative Example 1 is shown below. Figure 1 As shown, a macroscopic photograph of the molten sodium spreading on the surface of the composite solid electrolyte prepared in Example 1 is shown. Figure 2 As shown, from Figure 1 and Figure 2 As can be seen, the wettability of the composite solid electrolyte surface with molten sodium is significantly greater than that of the solid electrolyte surface with molten sodium.

[0120] The cross-sections of the first composites prepared in Comparative Application Example 1 and Application Example 1 were observed using scanning electron microscopy. The SEM images of the cross-sections of the first composites prepared in Comparative Application Example 1 are shown below. Figure 3 As shown, the cross-sectional SEM image of the first composite material prepared using Example 1 is as follows. Figure 4 As shown, from Figure 3 and Figure 4 As can be seen, the composite solid electrolyte has significantly better contact with the sodium anode.

[0121] Impedance measurements were performed on the solid sodium metal battery in Comparative Application Example 1 and Application Example 1 using an electrochemical workstation. The impedance spectrum of the solid sodium metal battery in Comparative Application Example 1 is shown below. Figure 5 As shown, the impedance spectrum of the solid sodium metal battery in Application Example 1 is as follows.Figure 6 As shown, from Figure 5 and Figure 6 As can be seen, the interfacial impedance between the sodium anode and the solid electrolyte in the comparative application example is as high as 493 Ω / cm. 2 This indicates extremely poor interfacial wettability; in the application example, the interfacial impedance between the Na negative electrode and the solid electrolyte drops to 48 Ω / cm. 2 This indicates that the composite solid electrolyte has significantly better wettability with the sodium anode, which is beneficial for interfacial electron / ion transport.

[0122] Cyclic tests were conducted using the Wuhan Landian Battery Testing System on the sodium-symmetric battery prepared with the solid electrolyte (NZSP electrolyte sheet) in Comparative Application Example 1 and the sodium-symmetric battery prepared with the composite solid electrolyte in Application Example 1. The constant current (0.1 mA·cm⁻¹) of the sodium-symmetric battery prepared with the solid electrolyte (NZSP electrolyte sheet) in Application Example 1 was compared. -2 ) Cyclic curve graph as shown Figure 7 As shown, the sodium symmetric battery prepared using the composite solid electrolyte in Example 1 has a constant current (0.3 mA·cm⁻¹). -2 ) Cyclic curve graph as shown Figure 8 As shown, from Figure 7 and Figure 8 As can be seen from the example, the battery prepared with the composite solid electrolyte (NZSP electrolyte sheet) in Application Example 1 can cycle stably for 2200 hours, which is much longer than that of the comparative Application Example 1.

[0123] The solid sodium metal battery in Case 1, corresponding to the Wuhan Landian Battery Testing System, was subjected to a cycle test at 0.5C. The resulting cycle performance graph is shown below. Figure 9 As shown, from Figure 9 As can be seen from the example, the solid sodium metal battery in Application Example 1 can cycle 300 times.

[0124] The electrochemical performance and cycle stability of the solid sodium metal batteries obtained in corresponding use cases 1-3 and comparative application examples 1-2 were tested:

[0125] Using an electrochemical workstation and the Wuhan Landian Battery Testing System, the internal resistance of solid sodium metal batteries and the symmetric cell values ​​obtained in corresponding test cases 1-3 and comparative application examples 1-2 were determined. -2 The stability of the solid sodium metal battery under the specified current density was tested, including the time and number of cycles. The cycle stability of the solid sodium metal battery obtained in the corresponding test cases 1-3 and the comparative application cases 1-2 was tested using the Wuhan Landian Battery Testing System. The test data are shown in Table 1.

[0126] Table 1 shows the performance test data of solid-state sodium metal batteries obtained from Application Examples 1-3 and Comparative Application Examples 1-2.

[0127]

[0128]

[0129] As can be seen from the data in Table 1, the internal resistance of the solid sodium metal battery prepared by the composite solid electrolyte obtained by the preparation method provided by the present invention is 48–74 Ω / cm. 2 Sodium-symmetric cells at 0.3 mA·cm -2 At a current density of 1900–2200 hours, the solid sodium metal battery can cycle up to 300 times at 0.5C with a capacity retention of 97.6%, exhibiting excellent electrochemical performance and cycle stability.

[0130] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a composite solid electrolyte, comprising: The precursor liquid was coated onto the surface of the solid electrolyte and then dried to obtain the composite solid electrolyte. The solid electrolyte is a NASICON type solid electrolyte; The precursor fluid includes a bismuth-containing precursor fluid and / or an antimony-containing precursor fluid; The method for preparing the bismuth-containing precursor liquid / antimony-containing precursor liquid includes: A mixture of bismuth chloride / antimony chloride and an organic solvent is mixed with water and subjected to a hydrolysis reaction to obtain a bismuth-containing precursor solution / antimony-containing precursor solution.

2. The preparation method according to claim 1, characterized in that, The ratio of the amount of bismuth chloride / antimony chloride in the mixture to the volume of the organic solvent is (0.1-1) mol: 1 L.

3. The preparation method according to claim 1, characterized in that, The molar ratio of bismuth chloride / antimony chloride to water is (0.1-1) mol: (1.7-13.5) mL.

4. The preparation method according to claim 1, characterized in that, The pH value for the hydrolysis reaction of the bismuth chloride and organic solvent mixture with water is 6.5 to 7.

5.

5. The preparation method according to claim 1, characterized in that, The pH value for the hydrolysis reaction of the mixture of antimony chloride and organic solvent with water is 0 to 1.

6. The preparation method according to claim 1, characterized in that, The coating method is spin coating, and the number of spin coatings is 1 to 3 times. After each spin coating is completed, drying is performed.

7. The preparation method according to claim 6, characterized in that, The volume of the precursor solution for each spin coating is 20–50 μL / cm³. 2 .

8. The composite solid electrolyte prepared by the preparation method according to any one of claims 1 to 7 comprises a solid electrolyte and a precursor layer on the surface of the solid electrolyte.

9. A method for preparing a solid-state sodium metal battery, characterized in that, include: Sodium metal is placed on the precursor layer on the surface of the solid electrolyte of the composite solid electrolyte of claim 8 and subjected to heat treatment to obtain the first composite. The first composite is assembled with the positive electrode to obtain a solid sodium metal battery.

10. The solid sodium metal battery prepared by the method of claim 9 comprises a sodium metal anode, an interface layer, a composite solid electrolyte, and a cathode arranged sequentially.

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