Composite solid electrolyte, solid sodium metal battery and preparation method of composite solid electrolyte and solid sodium metal battery

Abstract

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

Description

Technical Field

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

[0002] As raw materials for lithium batteries are rapidly depleted worldwide, the development of non-lithium batteries for energy storage systems is becoming increasingly important for establishing a sustainable energy usage pattern. As sodium has chemical and physical properties comparable to lithium, is abundant in reserves and has low cost, sodium batteries have become a very viable alternative to lithium batteries.

[0003] When the battery uses traditional organic liquid as the electrolyte, the metallic sodium anode, like the lithium anode, will also encounter problems such as uneven deposition / stripping and dendrite penetration, which can lead to potential safety issues such as short circuit and even combustion.

[0004] Replacing electrolytes with solid electrolytes can fundamentally solve the safety problem of batteries. However, the commonly used NASICON solid electrolyte will generate sodium-repellent Na2CO3 and NaOH on the surface under storage conditions, which will deteriorate the interface wettability, resulting in poor solid-solid contact at the electrolyte / negative electrode interface, hindering the transmission of sodium ions on the interface, causing a sharp increase in the internal resistance of all-solid-state sodium-ion batteries and deteriorating the battery's cycle performance. Summary of the invention

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

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

[0007] The present invention provides a method for preparing a composite solid electrolyte, comprising:

[0008] The precursor liquid is coated on the surface of the solid electrolyte and then dried to obtain a composite solid electrolyte;

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

[0010] The method for preparing the bismuth-containing precursor liquid / antimony-containing precursor liquid comprises:

[0011] The mixed solution of bismuth chloride / antimony chloride and an organic solvent is mixed with water for hydrolysis reaction to obtain a bismuth-containing precursor solution / antimony-containing precursor solution.

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

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

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

[0015] Preferably, the pH value of the hydrolysis reaction of the mixed solution of antimony chloride and the organic solvent mixed with water is 0-1.

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

[0017] Preferably, the volume of the precursor liquid for each spin coating is 20-50 μL / cm 2 .

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

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

[0020] placing metallic sodium on the precursor layer on the surface of the solid electrolyte and performing heat treatment to obtain a first composite;

[0021] The first complex is assembled with a positive electrode to obtain a solid-state sodium metal battery.

[0022] The present invention also provides a solid-state sodium metal battery prepared by the preparation method described in the above technical solution, comprising a metallic sodium negative electrode, an interface layer, a composite solid electrolyte and a positive electrode arranged in sequence.

[0023] The invention provides a method for preparing a composite solid electrolyte, comprising: spin coating a precursor liquid on a surface of a solid electrolyte and then drying the resultant to obtain a composite solid electrolyte; the precursor liquid comprises 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 comprises: mixing a mixed liquid of bismuth chloride / antimony chloride and an organic solvent with water for hydrolysis reaction to obtain a bismuth-containing precursor liquid / antimony-containing precursor liquid. The present invention coats the precursor liquid on the surface of the solid electrolyte, and uses the hydrochloric acid obtained by hydrolysis of bismuth chloride or antimony chloride to react with Na2CO3 and NaOH on the surface of the solid electrolyte to generate NaCl. NaCl can provide a fast ion diffusion channel, prevent electrons from entering the electrolyte, and inhibit dendrite growth. The composite solid electrolyte is used to prepare a solid-state sodium metal battery, and BiOCl and / or SbOCl formed by hydrolysis of bismuth chloride and / or antimony chloride contained in the composite solid electrolyte can be used to contact with the metal sodium negative electrode to generate Na3OCl and Na3Bi and / or Na3Sb alloys. Na3OCl can provide a fast ion diffusion channel, prevent electrons from entering the electrolyte, and inhibit dendrite growth. Na3Bi and / or Na3Sb alloys can not only increase interface contact, but also guide the uniform distribution of the electric field, regulate the uniform deposition of metal Na, and improve the electrochemical performance and cycle stability of the solid-state sodium metal battery. The results of the embodiment show that the battery internal resistance of the solid-state sodium metal battery prepared by the composite solid electrolyte prepared by the preparation method provided by the present invention is 48 to 74Ω / cm 2 , sodium symmetric battery at 0.3 mA cm -2 At a current density of , it can stably cycle for 1900 to 2200 hours. At 0.5C, the cycle number of solid-state sodium metal batteries can reach 300 times, and the capacity retention rate can reach 97.6%, which has good electrochemical performance and cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a macroscopic photograph of molten sodium spreading on the surface of the solid electrolyte prepared in Comparative Example 1 of the present 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 This is a cross-sectional SEM image of the first composite body prepared in Comparative Application Example 1 of the present invention;

[0027] Figure 4 This is a cross-sectional SEM image of the first composite body prepared in Application Example 1 of the present invention;

[0028] Figure 5 The impedance spectrum of the solid-state sodium metal battery in comparative application example 1 of the present invention;

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

[0030] Figure 7 The constant current (0.1 mA·cm) of the sodium symmetric battery prepared by the solid electrolyte (NZSP electrolyte sheet) in the comparative application example 1 of the present invention is -2 ) Cycle curve graph;

[0031] Figure 8 The constant current (0.3 mA·cm) of the sodium symmetric battery prepared by the composite solid electrolyte in Application Example 1 of the present invention -2 ) Cycle curve graph;

[0032] Fig. 9 This is a cycle performance diagram of the solid-state sodium metal battery in Application Example 1 of the present invention at 0.5C. DETAILED DESCRIPTION

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

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

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

[0036] In the present invention, when the precursor liquid includes a bismuth-containing precursor liquid and an antimony-containing precursor liquid, the present invention preferably mixes the bismuth-containing precursor liquid and the antimony-containing precursor liquid to obtain a precursor liquid, and then applies the precursor liquid. In the present invention, the volume ratio of the bismuth-containing precursor liquid to the antimony-containing precursor liquid is preferably 1:1.

[0037] In the present invention, the method for preparing the bismuth-containing precursor liquid / antimony-containing precursor liquid comprises:

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

[0039] As an embodiment of the present invention, the ratio of the amount of bismuth chloride / antimony chloride in the mixed solution to the volume of the organic solvent can be (0.1-1) mol: 1L, or (0.1-0.5) mol: 1L, or (0.1-0.3) mol: 1L. The present invention does not specifically limit the type of the organic solvent, and the bismuth chloride / antimony chloride can be dissolved by an organic solvent commonly used by those skilled in the art. In an embodiment of the present invention, the organic solvent can be isopropanol. The present invention limits the ratio of the amount of bismuth chloride / antimony chloride to the volume of the organic solvent to the above range, which can be beneficial to the spin coating of the precursor.

[0040] As an embodiment of the present invention, the ratio of the amount of bismuth chloride / antimony chloride to the volume of water 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. The present invention limits the ratio of the amount of bismuth chloride / antimony chloride to the volume of water to the above range to promote the hydrolysis of bismuth chloride / antimony chloride.

[0041] As an embodiment of the present invention, the pH value of the hydrolysis reaction of the mixed solution of bismuth chloride and organic solvent mixed with water can be 6.5-7.5, or 7. As an embodiment of the present invention, the pH adjuster adjusted to the pH value of the hydrolysis reaction can be ammonia water; the present invention does not specifically limit the amount and concentration of the ammonia water, and the pH can be adjusted to 6.5-7.5. In the present invention, the pH of the hydrolysis reaction of bismuth chloride is adjusted to neutral to obtain BiOCl precipitate.

[0042] As an embodiment of the present invention, the pH value of the hydrolysis reaction of the mixed solution of antimony chloride and organic solvent mixed with water can be 0-1, or 0.5. As an embodiment of the present invention, the pH adjuster adjusted to the pH value of the hydrolysis reaction can be a hydrochloric acid solution; the present invention does not specifically limit the amount and concentration of the hydrochloric acid solution, as long as the pH value of the hydrolysis reaction can be adjusted to 0-1. In the present invention, the pH value of the hydrolysis reaction of antimony chloride is adjusted to 0-1 to obtain SbOCl precipitation.

[0043] As an embodiment of the present invention, the mixing time may be 30 minutes; the mixing method may be stirring; the stirring speed may be 600-1000 rpm. The present invention can ensure that bismuth chloride / antimony chloride is fully hydrolyzed by limiting the stirring speed to the above range.

[0044] In the present invention, taking antimony chloride as an example, the equation of the hydrolysis reaction is shown in Formula 1:

[0045] SbCl3+H2O→SbOCl↓+2HCl Formula 1

[0046] As an embodiment of the present invention, the coating method can be spin coating; the number of spin coating can be 1 to 3 times, or 2 times; the rotation speed of each spin coating can be 800 to 2000 rpm, or 1200 to 1600 rpm; the volume of the precursor liquid for each spin coating can be 20 to 50 μL / cm 2 , and can be 30-40 μL / cm 2, and can also be 35μL / cm 2 The present invention limits the number of spin coatings, the rotation speed of each spin coating, and the volume of the precursor liquid for each spin coating to the above ranges, so that a precursor layer with a suitable thickness can be obtained.

[0047] The present invention preferably performs drying after each spin coating is completed; the drying is vacuum drying; as an embodiment of the present invention, the temperature of the vacuum drying can be 60-120°C, 80-100°C, or 90°C; the time of the vacuum drying can be 12-24h, 16-20h, or 18h. The present invention limits the drying method, temperature, and time to the above ranges to remove excess solvent, and react the hydrolysis product (HCl) in the precursor liquid on the surface of the solid electrolyte with Na2CO3 / NaOH that may be contained on the surface of the solid electrolyte to generate NaCl, which can provide a fast ion diffusion channel, prevent electrons from entering the electrolyte, and inhibit dendrite growth.

[0048] In the present invention, the solid electrolyte is a NASICON solid electrolyte; as an embodiment of the present invention, the solid electrolyte may be a NZSP solid electrolyte.

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

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

[0051] 2) wet-milling the precursor mixture obtained in step 1) with anhydrous ethanol as a medium, and then drying and calcining at one time to obtain a solid electrolyte pre-calcined powder; the calcination temperature is 1000° C., and the calcination time is 12 hours;

[0052] 3) wet-milling the solid electrolyte pre-calcined powder obtained in step 2) with anhydrous ethanol as a medium and then drying to obtain a solid electrolyte powder;

[0053] 4) The solid electrolyte powder obtained in step 3) is passed through a 200-mesh sieve, and the powder under the sieve is pressed into a green billet under a pressure of 250 MPa, and then sintered at 1230° C. for 12 hours, cooled, and surface polished to obtain a NZSP solid electrolyte.

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

[0055] As an embodiment of the present invention, the thickness of the precursor layer on the surface of the solid electrolyte may be 1 to 5 μm.

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

[0057] placing metallic sodium on the precursor layer on the surface of the solid electrolyte and performing heat treatment to obtain a first composite;

[0058] The first complex is assembled with a positive electrode to obtain a solid-state sodium metal battery.

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

[0060] In the present invention, the contact between the metallic sodium and the precursor layer on the surface of the composite solid electrolyte can make the BiOCl and / or SbOCl contained in the precursor layer contact with the metallic sodium negative electrode to generate Na3OCl and Na3Bi and / or Na3Sb alloys (forming an interface layer). Na3OCl can provide a fast ion diffusion channel, prevent electrons from entering the electrolyte, and inhibit dendrite growth. 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 metal Na, and improve the electrochemical performance and cycle stability of the solid-state sodium metal battery.

[0061] The present invention also provides a solid-state sodium metal battery prepared by the preparation method described in the above technical solution, comprising a metallic sodium negative electrode, an interface layer, a composite solid electrolyte and a positive electrode arranged in sequence.

[0062] As an 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 surface density of the positive electrode active material layer coated on the surface of the aluminum current collector may be 2 mg / cm 2 The positive electrode active material layer comprises 65wt% sodium vanadium phosphate, 15wt% NZSP powder, 10wt% conductive carbon and 10wt% PVDF.

[0063] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] Example 1

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

[0066] The precursor liquid was spin-coated on the surface of the solid electrolyte (the NZSP electrolyte sheet was placed at room temperature for ten days before use), and vacuum dried at 100°C for 12 hours after each spin coating to obtain a composite solid electrolyte; the spin coating was repeated twice; the rotation speed of each spin coating was 1600 rpm; the volume of the precursor liquid for each spin coating was 40 μL / cm 2 ;

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

[0068] The preparation method of the antimony-containing precursor liquid:

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

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

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

[0072] 2) wet-milling the precursor mixture obtained in step 1) with anhydrous ethanol as a medium, and then drying and calcining at one time to obtain a solid electrolyte pre-calcined powder; the calcination temperature is 1000° C., and the calcination time is 12 hours;

[0073] 3) wet-milling the solid electrolyte pre-calcined powder obtained in step 2) with anhydrous ethanol as a medium and then drying to obtain a solid electrolyte powder;

[0074] 4) The solid electrolyte powder obtained in step 3) is passed through a 200-mesh sieve, and the powder under the sieve is pressed into a green billet under a pressure of 250 MPa, and then sintered at 1230° C. for 12 hours, cooled, and surface polished to obtain a NZSP solid electrolyte sheet.

[0075] The composite solid electrolyte prepared by the preparation 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:

[0078] The precursor liquid was spin-coated on the surface of the solid electrolyte (the NZSP electrolyte sheet was placed at room temperature for ten days before use), and vacuum dried at 80°C for 24 hours after each spin coating to obtain a composite solid electrolyte; the spin coating was repeated three times; the rotation speed of each spin coating was 2000 rpm; the volume of the precursor liquid for each spin coating was 20 μL / cm 2 ;

[0079] The precursor liquid is a precursor liquid containing bismuth;

[0080] The preparation method of the bismuth-containing precursor liquid:

[0081] After BiCl3 and isopropanol are mixed to form a 0.1 mol / L solution, water is added, and the pH value is adjusted to 7 with ammonia water (0.1 mol / L), and the mixture is stirred at 600 rpm for 30 min for hydrolysis reaction to obtain a precursor liquid; the volume ratio of the amount of BiCl3 to water is 0.5 mol:10 mL;

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

[0083] The composite solid electrolyte prepared by the preparation 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:

[0086] The precursor liquid was spin-coated on the surface of the solid electrolyte (the NZSP electrolyte sheet was placed at room temperature for ten days before use), and vacuum dried at 110°C for 12 hours after each spin coating to obtain a composite solid electrolyte; the number of spin coatings was 1 time; the rotation speed of each spin coating was 1000 rpm; the volume of the precursor liquid for each spin coating was 30 μL / cm2 ;

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

[0088] The preparation method of the antimony-containing precursor liquid and the bismuth-containing precursor liquid:

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

[0090] After BiCl3 and isopropanol are mixed to form a 0.1 mol / L solution, water is added, and the pH value is adjusted to 7 with ammonia water (0.1 mol / L), and the mixture is stirred at 600 rpm for 30 min for hydrolysis reaction to obtain a bismuth-containing precursor liquid; the volume ratio of the amount of BiCl3 to water is 0.5 mol:10 mL;

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

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

[0093] The composite solid electrolyte prepared by the preparation 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:

[0096] The precursor liquid was spin-coated on the surface of the solid electrolyte (the NZSP electrolyte sheet was placed at room temperature for ten days before use), and vacuum dried at 80°C for 12 hours after each spin coating to obtain a composite solid electrolyte; the spin coating was repeated three times; the rotation speed of each spin coating was 2000 rpm; the volume of the precursor liquid for each spin coating was 20 μL / cm 2 ;

[0097] The preparation method of the precursor liquid:

[0098] BiOCl and isopropanol were mixed 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 that of Example 1.

[0100] The composite solid electrolyte prepared by the preparation 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] Placing metallic sodium on the precursor layer on the surface of the composite solid electrolyte prepared in Example 1 and heat treating it at 100° C. for 30 minutes to obtain a first composite;

[0104] Assembling the first composite with a positive electrode to obtain a solid-state sodium metal battery;

[0105] The solid-state sodium metal battery prepared by the preparation method is composed of a metal sodium negative electrode, an interface layer, a composite solid electrolyte and a positive electrode arranged in sequence;

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

[0107] Application Example 2

[0108] The only difference between Application Example 2 and Application Example 1 is that in the preparation method of the solid-state 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 a first composite, and the rest is the same as Application Example 1.

[0109] Application Example 3

[0110] The only difference between Application Example 3 and Application Example 1 is that in the preparation method of the solid-state 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 a first composite, and the rest 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 metal sodium negative electrode is placed on a solid electrolyte (NZSP electrolyte sheet) and heat treated at 120° C. for 30 min to obtain a first composite;

[0114] Assembling the first composite with a positive electrode to obtain a solid-state sodium metal battery;

[0115] The solid-state sodium metal battery prepared by the preparation method is composed of a metallic sodium negative electrode, an interface layer, a solid electrolyte (NZSP electrolyte sheet) and a positive electrode arranged in sequence;

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

[0117] Comparative Application Example 2

[0118] The difference between Comparative Application Example 2 and Application Example 2 is only in the preparation method of the solid-state sodium metal battery, in which 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 minutes to obtain a first composite, and the rest is the same as Application Example 2.

[0119] The surface of the solid electrolyte prepared in Comparative Example 1 and the surface of the composite solid electrolyte prepared in Example 1 were brought into contact with molten sodium, and the wettability of metallic sodium with the solid electrolyte and the composite solid electrolyte was observed. The macroscopic photograph of the spread of molten sodium on the surface of the solid electrolyte prepared in Comparative Example 1 is shown in FIG. Figure 1 As shown, the macroscopic photograph of the molten sodium spreading on the surface of the composite solid electrolyte prepared in Example 1 is as follows Figure 2 As shown, from Figure 1 and Figure 2 It can be seen that 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-section of the first composite prepared in Comparative Application Example 1 and Application Example 1 was observed using a scanning electron microscope. The cross-section SEM image of the first composite prepared in Comparative Application Example 1 is as follows: Figure 3 As shown, the cross-sectional SEM image of the first composite prepared in Application Example 1 is as follows Figure 4 As shown, from Figure 3 and Figure 4 It can be seen that the composite solid electrolyte has obviously better contact with the sodium negative electrode.

[0121] The impedance of the solid-state sodium metal battery in Comparative Application Example 1 and Application Example 1 was tested using an electrochemical workstation. The impedance spectrum of the solid-state sodium metal battery in Comparative Application Example 1 is shown in FIG. Figure 5 As shown, the impedance spectrum of the solid-state sodium metal battery in Application Example 1 is as follows Figure 6 As shown, from Figure 5 and Figure 6 It can be seen that the interface impedance between the sodium negative electrode and the solid electrolyte in the comparative application example is as high as 493Ω / cm 2 , indicating that the interface wettability is extremely poor; in the application example, the interface impedance between the Na negative electrode and the solid electrolyte is reduced to 48Ω / cm 2 , indicating that the composite solid electrolyte has better wettability with the sodium negative electrode, which is beneficial to the interfacial electron / ion transport.

[0122] Wuhan Blue Electric Battery Test System was used to perform cycle tests 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 -2 ) The cycle curve is as follows Figure 7 As shown in the figure, the constant current (0.3 mA cm) of the sodium symmetric battery prepared by the composite solid electrolyte in Example 1 -2 ) The cycle curve is as follows Figure 8 As shown, from Figure 7 and Figure 8 It can be seen that the battery prepared with the composite solid electrolyte (NZSP electrolyte sheet) in Application Example 1 can be stably cycled for 2200 hours, which is much longer than Comparative Application Example 1.

[0123] The Wuhan Blue Electric Battery Test System was used to perform a cycle test on the solid-state sodium metal battery in Example 1 at 0.5C. The cycle performance diagram is shown in the figure below. Fig. 9 As shown, from Fig. 9 It can be seen that the solid-state sodium metal battery in Application Example 1 can be cycled 300 times.

[0124] The electrochemical performance and cycle stability of the solid-state sodium metal batteries obtained in Examples 1 to 3 and Comparative Application Examples 1 to 2 were tested:

[0125] The battery internal resistance and symmetrical battery resistance of the solid-state sodium metal battery obtained in Examples 1 to 3 and Comparative Application Examples 1 to 2 were measured by using an electrochemical workstation and Wuhan Blue Electric Battery Test System at 0.3 mA cm -2 The stable cycle time and number of cycles under the current density were tested, and the cycle stability of the solid-state sodium metal batteries obtained in Example 1 to 3 and Comparative Application Examples 1 to 2 were tested using Wuhan Blue Electric Battery Testing System. The test data are shown in Table 1.

[0126] Table 1 Performance test data of solid-state sodium metal batteries obtained in application examples 1 to 3 and comparative application examples 1 to 2

[0127]

[0128]

[0129] It can be seen from the data in Table 1 that the internal resistance of the solid-state sodium metal battery prepared by the composite solid electrolyte prepared by the preparation method provided by the present invention is 48 to 74 Ω / cm 2 , sodium symmetric battery at 0.3 mA cm -2 At a current density of , it can stably cycle for 1900 to 2200 hours. At 0.5C, the cycle number of solid-state sodium metal batteries can reach 300 times, and the capacity retention rate can reach 97.6%, which has good electrochemical performance and cycle stability.

[0130] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a composite solid electrolyte, comprising: The precursor liquid is coated on the surface of the solid electrolyte and then dried 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 comprises: The mixed solution of bismuth chloride / antimony chloride and an organic solvent is mixed with water for 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 mixed solution to the volume of the organic solvent is (0.1-1) mol:1L.

3. The preparation method according to claim 1, characterized in that: The ratio of the amount of bismuth chloride / antimony chloride to the volume of 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 of the hydrolysis reaction of the mixed solution of bismuth chloride and organic solvent mixed with water is 6.5-7.

5.

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

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

7. The preparation method according to claim 6, characterized in that: The volume of the precursor liquid for each spin coating is 20-50 μL / cm 2 .

8. The composite solid electrolyte prepared by the preparation method according to any one of claims 1 to 7, comprising 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: placing metallic sodium on the precursor layer on the surface of the solid electrolyte and performing heat treatment to obtain a first composite; The first complex is assembled with a positive electrode to obtain a solid-state sodium metal battery.

10. The solid-state sodium metal battery prepared by the preparation method of claim 9, comprising a metallic sodium negative electrode, an interface layer, a composite solid electrolyte and a positive electrode arranged in sequence.

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