Improved na-beta"-al2o3 solid electrolyte, method of preparation and use

Abstract

The application provides an improved Na-beta''-Al2O3 solid electrolyte, a preparation method and application, and belongs to the technical field of solid-state sodium batteries. The technology aims to solve the problem of poor interface contact between traditional Na-beta''-Al2O3 materials and sodium anodes. The key of the application lies in adopting a specific element doping strategy, and the doping element is at least one of Mg, Sn, Ga, In, Ti, Pb and Zn, and in-situ alloying at the interface between the electrolyte and the sodium metal electrode. This alloying process does not require additional coating or intermediate layer, and is spontaneously formed during assembly, and greatly improves the interface stability. The results show that the method not only improves the overall performance of the electrolyte, but also ensures the cycle stability and rate performance of the full solid-state sodium metal battery. The strategy has achieved significant progress in interface engineering, and provides reliable technical support and theoretical guidance for the development of high-performance sodium ion solid-state batteries.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid-state sodium batteries, in particular to an improved Na-β''-Al2O3 solid electrolyte, a preparation method and application. BACKGROUND

[0002] In the solid electrolyte of solid-state sodium batteries, Na-β''-Al2O3 is suitable for high energy density and high voltage applications due to its wide electrochemical stability window and excellent stability to metallic sodium. However, its practical application still faces significant interface contact problems. Na-β''-Al2O3 has poor wettability to sodium, making it difficult to form stable electrode-electrolyte contact. During the charge and discharge cycle, the interface between Na-β''-Al2O3 and the sodium anode is prone to degradation, leading to an increase in interface impedance and affecting the overall performance of the battery. In addition, unstable interface is also prone to the formation of sodium dendrites, which not only pierce the electrolyte layer and cause short circuits, but also accelerate the aging of the interface and shorten the service life of the battery.

[0003] Additional coatings or intermediate layers are introduced, high-temperature treatment is used to enhance the interface bonding force, and higher mechanical pressure is applied to improve the interface contact. Although these methods can improve the interface stability to some extent, they also have obvious limitations. For example, the introduction of additional coatings or intermediate layers increases the manufacturing complexity and cost, and may introduce new chemical reaction risks; high-temperature treatment has limited material selection and increases process difficulty and cost; the application of higher mechanical pressure requires higher packaging precision and structural strength, limiting its wide application. Therefore, the existing interface modification technology has not fundamentally solved the problem, especially in terms of maintaining low cost and simplifying the process.

[0004] Therefore, there is an urgent need for an interface modification technology that is low-cost and achieves stable interface under low stacking pressure to solve the above problems. SUMMARY

[0005] The purpose of the present application is to provide an improved Na-β''-Al2O3 solid electrolyte, a preparation method and application. The use of element doping combined with in-situ alloying technology can significantly improve the interface stability between the Na-β''-Al2O3 solid electrolyte and the sodium anode.

[0006] To achieve the above purpose, the present application provides an improved Na-β''-Al2O3 solid electrolyte, which is pretreated on the surface before assembling the battery, and then in-situ alloying is performed by heating and ultrasonic welding;

[0007] Vanadium iron sodium phosphate, sodium vanadate or layered TM oxide (Na xThe modified Na-β"-Al2O3 solid electrolyte is used as a negative electrode, and a positive electrode is prepared by using TMO2 (TM=Fe, Mn, Ni, Co, Cr, Ti, V and combinations thereof) as a positive electrode, 5-10 μL of an electrolyte (NaClO4 or NaPF6 sodium salt combined with EC / PC / DMC / PC solvent) is dropped on the other side surface of the modified Na-β"-Al2O3 solid electrolyte, and a solid sodium battery is assembled by using a nickel mesh or a spring.

[0008] Preferably, the pretreatment is acid pickling or heat treatment.

[0009] The acid solution used in the acid pickling is a mixture of one or more of dilute hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid, and the acid solution is coated on the surface of the modified Na-β"-Al2O3 solid electrolyte for 10 s-1 min.

[0010] The heat treatment temperature is 500-900 ℃, and the heat treatment time is 1-4 hours.

[0011] Preferably, the heating temperature is 50-80 ℃.

[0012] Preferably, the ultrasonic welding frequency is 40-50 KHz, and the welding time is 30 s-2 min.

[0013] The application also provides a preparation method of the modified Na-β"-Al2O3 solid electrolyte, comprising the following steps:

[0014] Step S1, selecting a Na-β"-Al2O3 precursor material, including sodium carbonate, sodium hydroxide, aluminum oxide and aluminum hydroxide;

[0015] Selecting a doping raw material, including one or several combinations of oxides, carbonates or hydroxides of Mg, Sn, Ga, In, Ti, Pb and Zn;

[0016] According to the target molecular formula Na 1+y M x Al 10+z O 17 Weighing the corresponding raw materials and mixing them with the Na-β"-Al2O3 precursor material, and uniformly mixing the materials by using a ball mill, wherein M is the doping raw material, x is 0-0.67, y is 0-1, and z is 0-1;

[0017] Step S2, preliminarily sintering the mixed powder at a temperature in the range of 1200-1500 ℃ for 2-4 h to obtain a preliminary solid electrolyte precursor;

[0018] Step S3, using a pressing forming method to obtain a ceramic green body from the sintered and dried powder of the preliminary solid electrolyte precursor, and placing the ceramic green body in a high-temperature furnace for sintering treatment, and naturally cooling or controlling the cooling rate according to a predetermined program (2-5 ℃ / min) after the sintering is completed.

[0019] Preferably, for Ga element doping, Na-β"-Al2O3(Na 1.77 Al 11 O 17 ) and Na-β"-Ga2O3(Na 1.98 Ga 10.67 O 17 ) preliminary solid electrolyte precursor powders are synthesized respectively, and then the two are ball-mixed and pressed to form a ceramic green body according to the ratio of Na 1.77 Al (11-n) Ga n O 17 (n=0-1).

[0020] Preferably, in step S1, the rotation speed of the ball mill is 300-1200r / min, and the ball milling time is 1-12h.

[0021] Preferably, in step S3, the pressure during the pressing is 200-300MPa, and the pressing time is 5-30min.

[0022] Preferably, in step S3, the sintering temperature is 1400-1600℃.

[0023] The application also provides an improved Na-β"-Al2O3 solid electrolyte prepared by the improved Na-β"-Al2O3 solid electrolyte preparation method.

[0024] Therefore, the improved Na-β"-Al2O3 solid electrolyte, preparation method and application have the following beneficial technical effects:

[0025] During the battery assembly process, a stable alloy layer is spontaneously formed between the sodium anode and the electrolyte, without the need for additional coating or intermediate layer, simplifying the manufacturing process and reducing the cost. The formed alloy layer significantly enhances the wettability of the electrolyte to sodium, ensuring good electrode-electrolyte contact and reducing the interfacial resistance. At the same time, the stable alloy interface effectively inhibits the formation of sodium dendrites, improving the safety and cycle life of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The density of the Na 1.67 Mg 0.67 Al 10.33 O 17 solid electrolyte ceramic sheet under different sintering conditions in Example One;

[0027] Figure 2 The density of the Na 1.77 Al10 GaO 17 SEM and EDS results of solid electrolyte ceramic sheet; wherein, Figure 2 (a) in the above table is Na 1.77 Al 10 GaO 17 SEM image of solid electrolyte ceramic sheet; Figure 2 (b) in the above table is Na 1.77 Al 10 GaO 17 Corresponding surface distribution EDS results of Al element of solid electrolyte ceramic sheet; Figure 2 (c) in the above table is Na 1.77 Al 10 GaO 17 Corresponding surface distribution EDS results of Na element of solid electrolyte ceramic sheet; Figure 2 (d) in the above table is Na 1.77 Al 10 GaO 17 Corresponding surface distribution EDS results of Ga element of solid electrolyte ceramic sheet; Figure 2 (e) in the above table is Na 1.77 Al 10 GaO 17 Corresponding surface distribution EDS results of O element of solid electrolyte ceramic sheet;

[0028] Figure 3 Na, Mg, Al and GaO contents of solid electrolyte ceramic sheets under different sintering conditions in Example Three 1.67 Mg 0.67 Al 9.33 GaO 17 Density of solid electrolyte ceramic sheet;

[0029] Figure 4 Na, Mg, Al and GaO contents of solid electrolyte ceramic sheets after sintering at 1550℃ for 2h in Example Three 1.67 Mg 0.67 Al 9.33 GaO 17 SEM and EDS results of solid electrolyte ceramic sheet; wherein, Figure 4 (a) in the above table is Na 1.67 Mg 0.67 Al 9.33 GaO 17 SEM image of solid electrolyte ceramic sheet; Figure 4 (b) in the above table is Na 1.67 Mg 0.67 Al 9.33 GaO 17 Corresponding surface distribution EDS results of Al element of solid electrolyte ceramic sheet; Figure 4 (c) in the above table is Na 1.67 Mg 0.67 Al9.33 GaO 17 The corresponding surface distribution EDS results of O element of the solid electrolyte ceramic sheet; Figure 4 (d) in the above table is Na 1.67 Mg 0.67 Al 9.33 GaO 17 The corresponding surface distribution EDS results of Ga element of the solid electrolyte ceramic sheet; Figure 4 (e) in the above table is Na 1.67 Mg 0.67 Al 9.33 GaO 17 The corresponding surface distribution EDS results of Na element of the solid electrolyte ceramic sheet; Figure 4 (f) in the above table is Na 1.67 Mg 0.67 Al 9.33 GaO 17 The corresponding surface distribution EDS results of Mg element of the solid electrolyte ceramic sheet;

[0030] Figure 5 Na in Example Three after sintering at 1550℃ for different time 1.67 Mg 0.67 Al 9.33 GaO 17 The temperature-dependent ionic conductivity of the solid electrolyte ceramic sheet;

[0031] Figure 6 Na in Example Four under different sintering conditions 1.67 Zn 0.67 Al 10.33 O 17 The density of the solid electrolyte ceramic sheet;

[0032] Figure 7 Na in Example Five under different sintering conditions 1.67 Pb 0.67 Al 10.33 O 17 The density of the solid electrolyte ceramic sheet;

[0033] Figure 8 Na in Example Six under different sintering conditions 1.67 Sn 0.33 Al 10.33 O 17 The density of the solid electrolyte ceramic sheet;

[0034] Figure 9 The original Na in Example Seven 1.67 Mg 0.67 Al 9.33 GaO 17Ceramic electrolyte sheet and C1s, Na 1s comparison after acid treatment and vacuum heat treatment and C1s, Na 1s spectra alone; wherein, Figure 9 (a) is Na 1.67 Mg 0.67 Al 9.33 GaO 17 Change in C1s spectra from original, acid treatment, vacuum heat treatment; Figure 9 (b) is Na 1.67 Mg 0.67 Al 9.33 GaO 17 Original C1s spectra; Figure 9 (c) is Na 1.67 Mg 0.67 Al 9.33 GaO 17 C1s spectra after acid treatment; Figure 9 (d) is Na 1.67 Mg 0.67 Al 9.33 GaO 17 C1s spectra after heat treatment; Figure 9 (e) is Na 1.67 Mg 0.67 Al 9.33 GaO 17 Change in Na 1s spectra from original, acid treatment, vacuum heat treatment; Figure 9 (f) is Na 1.67 Mg 0.67 Al 9.33 GaO 17 Original Na 1s spectra; Figure 9 (g) is Na 1.67 Mg 0.67 Al 9.33 GaO 17 Na 1s spectra after acid treatment; Figure 9 (h) is Na 1.67 Mg 0.67 Al 9.33 GaO 17 C1s spectra after heat treatment;

[0035] Figure 10 Example Eight using Na 1.67 Mg 0.67 Al 10.33 O 17 STEM and EDS images of the interface of a coin cell assembled with the ceramic sheet after cycling; wherein, Figure 10 (a) is Na 1.67 Mg 0.67 Al 10.33 O17 STEM image of the interface between the ceramic sheet and sodium metal; Figure 10 (b) in (a) is Na 1.67 Mg 0.67 Al 10.33 O 17 Corresponding surface distribution EDS results of Na element of the interface between the ceramic sheet and sodium metal; Figure 10 (c) in (a) is Na 1.67 Mg 0.67 Al 10.33 O 17 Corresponding surface distribution EDS results of Mg element of the interface between the ceramic sheet and sodium metal; Figure 10 (d) in (a) is Na 1.67 Mg 0.67 Al 10.33 O 17 Corresponding surface distribution EDS results of Al element of the interface between the ceramic sheet and sodium metal; Figure 10 (e) in (a) is Na 1.67 Mg 0.67 Al 10.33 O 17 Corresponding surface distribution EDS results of O element of the interface between the ceramic sheet and sodium metal;

[0036] Figure 11 STEM and EDS images of the interface between the ceramic sheet and sodium metal after ultrasonic welding in Example Nine; wherein, 1.67 Mg 0.67 Al 9.33 GaO 17 SEM and line EDS images of the interface between the ceramic sheet and sodium metal; wherein, Figure 11 (a) in (a) is Na 1.67 Mg 0.67 Al 9.33 GaO 17 SEM images of the interface between the ceramic sheet and sodium metal; Figure 11 (b) in (a) is Na 1.67 Mg 0.67 Al 9.33 GaO 17 Line EDS images of the interface between the ceramic sheet and sodium metal;

[0037] Figure 12 STEM and EDS images of the interface between the ceramic sheet and sodium metal after assembling the button cell in Example Nine; wherein, 1.67 Mg 0.67 Al 9.33 GaO 17 STEM and EDS images of the interface between the ceramic sheet and sodium metal after assembling the button cell in Example Nine; wherein, Figure 12 (a) in (a) is Na 1.67 Mg 0.67 Al 9.33 GaO 17STEM image of the interface between the ceramic sheet and sodium metal; Figure 12 (b) in FIG. 1 is Na 1.67 Mg 0.67 Al 9.33 GaO 17 Corresponding surface distribution EDS results of Al element of the interface between the ceramic sheet and sodium metal; Figure 12 (c) in FIG. 2 is Na 1.67 Mg 0.67 Al 9.33 GaO 17 Corresponding surface distribution EDS results of Mg element of the interface between the ceramic sheet and sodium metal; Figure 12 (d) in FIG. 3 is Na 1.67 Mg 0.67 Al 9.33 GaO 17 Corresponding surface distribution EDS results of Na element of the interface between the ceramic sheet and sodium metal; Figure 12 (e) in FIG. 4 is Na 1.67 Mg 0.67 Al 9.33 GaO 17 Corresponding surface distribution EDS results of Ga element of the interface between the ceramic sheet and sodium metal; Figure 12 (f) in FIG. 5 is Na 1.67 Mg 0.67 Al 9.33 GaO 17 Corresponding surface distribution EDS results of O element of the interface between the ceramic sheet and sodium metal;

[0038] Figure 13 Na 1.67 Mg 0.67 Al 9.33 GaO 17 Ceramic sheet assembled button cell at 0.1 mA / cm 2 Na deposition stripping curve of current density cycle;

[0039] Figure 14 Na 1.67 Mg 0.67 Al 9.33 GaO 17 Rate performance of ceramic sheet button cell at 30°C;

[0040] Figure 15 Na 1.67 Mg 0.67 Al 9.33 GaO 17 and Na 1.67 Mg 0.67 Al 10.33 O 17Cycling performance of ceramic sheet assembled 2032 button cell at 30℃ 1C. DETAILED DESCRIPTION

[0041] The technical solutions of the present application are further illustrated by the accompanying drawings and examples.

[0042] Unless otherwise defined, technical or scientific terms used in the present application shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0043] Example 1

[0044] A Na 1.67 Mg 0.67 Al 10.33 O 17 Solid electrolyte, using sodium carbonate, magnesium oxide, γ-alumina as raw materials, according to Na 1.67 Mg 0.67 Al 10.33 O 17 About 10g of stoichiometric ratio was taken, with 7.5% excess of Na2CO3, placed in a 100ml zirconia ball mill jar, according to the ball-to-material ratio of 6:1, 40ml of anhydrous ethanol was added. In the planetary ball mill, the mixture was ball milled at 300rpm for 12h. After taking out, it was transferred to the oven and dried for 12h, then the powder was transferred to an alumina crucible and sintered at a temperature of 1200℃ for 2h, with a heating rate of 5℃ / min. Then the sintering ball milling was repeated twice to obtain Na 1.67 Mg 0.67 Al 10.33 O 17 The precursor powder was added with 1wt% PVA124 binder, sieved through a 100 mesh sieve, and then pressed into shape using a mold with a diameter of 8-15mm, followed by secondary shaping in a cold isostatic press with a forming pressure of 300MPa. After taking out, the four sides were buried with loose precursor powder to ensure uniform heating and prevent deformation, and to compensate for sodium loss at high temperature. The heating rate was 2℃ / min, and the optimized sintering temperature was 1450-1550℃.

[0045] Figure 1 Na 1.67 Mg 0.67 Al 10.33 O 17 Solid electrolyte ceramic sheet density.

[0046] Example 2

[0047] A Na 1.77 Al 10 GaO 17A solid electrolyte, using sodium carbonate, magnesium oxide, gallium oxide, γ-alumina as raw materials, according to Na 1.77 Al 10 GaO 17 The stoichiometric ratio of about 10 g was taken, wherein Na2CO3 was 7.5% excess, placed in a 100 ml zirconium oxide ball mill jar, according to the ball material ratio 6:1, 40 ml of anhydrous ethanol was added. In the planetary ball mill, the mixture was ball milled at 300 rpm for 12 h. After taking out, it was transferred into an oven and dried for 12 h, then the powder was transferred to an alumina crucible and sintered at a temperature of 1200 ℃ for 2 h, the heating rate was 5 ℃ / min. Then the sintering ball milling was repeated twice to obtain Na 1.77 Al 10 GaO 17 The precursor powder. The precursor powder was added with 1wt% PVA124 binder, after passing through a 100 mesh sieve, it was formed by using a mold with a diameter of 8-15 mm, and then secondary formed by a cold isostatic pressing machine, the forming pressure was 300 MPa. After taking out, it was buried with loose precursor powder around to make the green body uniformly heated and prevent deformation and compensate for sodium loss at high temperature. The heating rate was 2 ℃ / min, and the sintering temperature was 1550 ℃.

[0048] Figure 2 Na 1.77 Al 10 GaO 17 The SEM and EDS results of the solid electrolyte ceramic sheet.

[0049] Example Three

[0050] A Na 1.67 Mg 0.67 Al 9.33 GaO 17 A solid electrolyte, using sodium carbonate, gallium oxide, magnesium oxide as raw materials, according to Na 1.67 Mg 0.67 Ga 10.33 O 17 The stoichiometric ratio of about 10 g was taken, wherein Na2CO3 was 7.5% excess, ball milling and sintering were carried out, and sintering was carried out at a temperature of 1280 ℃ for 2 h, the heating rate was 5 ℃ / min. Then the sintering ball milling was repeated twice to obtain Na 1.67 Mg 0.67 Ga 10.33 O 17 The precursor powder. The precursor powder was added with 1wt% PVA124 binder, after passing through a 100 mesh sieve, it was formed by using a mold with a diameter of 8-15 mm, and then secondary formed by a cold isostatic pressing machine, the forming pressure was 300 MPa. After taking out, it was buried with loose precursor powder around to make the green body uniformly heated and prevent deformation and compensate for sodium loss at high temperature. The heating rate was 2 ℃ / min, and the sintering temperature was 1550 ℃. 1.67 Mg 0.67 Al 10.33 O 17 The precursor powder. The precursor powder was added with 1wt% PVA124 binder, after passing through a 100 mesh sieve, it was formed by using a mold with a diameter of 8-15 mm, and then secondary formed by a cold isostatic pressing machine, the forming pressure was 300 MPa. After taking out, it was buried with loose precursor powder around to make the green body uniformly heated and prevent deformation and compensate for sodium loss at high temperature. The heating rate was 2 ℃ / min, and the sintering temperature was 1550 ℃. 1.67 Mg0.67 Al 9.33 GaO 17 The powders were mixed in stoichiometric ratio by ball milling. The green bodies were formed by die pressing with a die diameter of 8-15 mm, followed by cold isostatic pressing with a forming pressure of 300 MPa. After removal, the green bodies were buried in loose precursor powder to prevent deformation and compensate for sodium loss at high temperature. The heating rate was 2°C / min, and the optimized sintering temperature was 1450-1550°C.

[0051] Figure 3 Na 1.67 Mg 0.67 Al 9.33 GaO 17 Density of the solid electrolyte ceramic pellets.

[0052] Figure 4 Na 1.67 Mg 0.67 Al 9.33 GaO 17 SEM and EDS results of the solid electrolyte ceramic pellets.

[0053] Figure 5 Na 1.67 Mg 0.67 Al 9.33 GaO 17 Temperature-dependent ionic conductivity of the solid electrolyte ceramic pellets.

[0054] Example Four

[0055] A Na 1.67 Zn 0.67 Al 10.33 O 17 Solid electrolyte, using sodium carbonate, zinc oxide, and γ-alumina as raw materials, according to the stoichiometric ratio of Na 1.67 Zn 0.67 Al 10.33 O 17 About 10 g of the stoichiometric mixture was weighed, with Na2CO3 being in excess by 7.5%, and placed in a 100 ml zirconia ball mill jar. Zirconia grinding balls with a diameter of 3-5 mm were added according to a ball-to-powder ratio of 6:1, followed by the addition of 40 ml of anhydrous ethanol. The mixture was ball-milled in a planetary ball mill at 300 rpm for 12 h. After removal, the powder was transferred to an oven for drying for 12 h, and then the powder was transferred to an alumina crucible and sintered at a temperature of 1200°C for 2 h, with a heating rate of 5°C / min. The sintered pellets were then ball-milled twice to obtain Na 1.67 Zn 0.67 Al 10.33 O 17Precursor powder. The precursor powder is added with 1wt% PVA124 binder, sieved through a 100 mesh sieve, and then compression molded using a mold with a diameter of 8-15 mm, and then secondary molded using a cold isostatic press at a molding pressure of 300 MPa. After removal, the green body is buried in loose precursor powder around the four sides to uniformly heat the green body around the four sides and prevent deformation and compensate for sodium loss at high temperatures. The heating rate is 2°C / min, and the optimized sintering temperature is 1450-1550°C.

[0056] Figure 6 Na 1.67 Zn 0.67 Al 10.33 O 17 Solid electrolyte ceramic sheet density.

[0057] Example five

[0058] A Na 1.67 Pb 0.67 Al 10.33 O 17 Solid electrolyte, using sodium carbonate, lead oxide, and γ-alumina as raw materials, according to Na 1.67 Pb 0.67 Al 10.33 O 17 About 10 g of stoichiometric ratio is weighed, with Na2CO3 being 7.5% excess, and placed in a 100 ml zirconium oxide ball mill jar. Zirconium oxide grinding balls with a diameter of 3-5 mm are added according to a ball-to-material ratio of 6:1, followed by the addition of 40 ml of anhydrous ethanol. The mixture is ball milled in a planetary ball mill at 300 rpm for 12 h. After removal, it is transferred to an oven for drying for 12 h, and then the powder is transferred to an alumina crucible and sintered at a temperature of 1200°C for 2 h, with a heating rate of 5°C / min. The sintered ball is then repeated twice to obtain Na 1.67 Pb 0.67 Al 10.33 O 17 Precursor powder. The precursor powder is added with 1wt% PVA124 binder, sieved through a 100 mesh sieve, and then compression molded using a mold with a diameter of 8-15 mm, and then secondary molded using a cold isostatic press at a molding pressure of 300 MPa. After removal, the green body is buried in loose precursor powder around the four sides to uniformly heat the green body around the four sides and prevent deformation and compensate for sodium loss at high temperatures. The heating rate is 2°C / min, and the optimized sintering temperature is 1450-1550°C.

[0059] Figure 7 Na 1.67 Pb 0.67 Al 10.33 O 17 Solid electrolyte ceramic sheet density.

[0060] Example Six

[0061] A Na 1.67 Sn 0.33 Al 10.33 O 17 Solid electrolyte, using sodium carbonate, magnesium oxide, γ-alumina as raw materials, according to Na 1.67 Sn 0.33 Al 10.33 O 17 About 10g of stoichiometric ratio was taken, where Na2CO3 was 7.5% excess, placed in a 100ml zirconium oxide ball mill jar, according to the ball material ratio 6:1, 40ml of anhydrous ethanol was added. In the planetary ball mill, the mixture was ball milled at 300rpm for 12h. After taking out, it was transferred to the oven and dried for 12h, then the powder was transferred to an alumina crucible and sintered at a temperature of 1200℃ for 2h, the heating rate was 5℃ / min. Then the sintering ball milling was repeated twice to obtain Na 1.67 Sn 0.33 Al 10.33 O 17 The precursor powder was added with 1wt% PVA124 binder, after passing through a 100 mesh sieve, it was pressed into a mold with a diameter of 8-15mm, and then cold isostatic pressing was used for secondary forming, with a forming pressure of 300MPa. After taking out, the four sides were buried with loose precursor powder to make the green body uniformly heated and prevent deformation and compensate for sodium loss at high temperature. The heating rate was 2℃ / min, and the optimized sintering temperature was 1450-1550℃.

[0062] Figure 8 Na 1.67 Sn 0.33 Al 10.33 O 17 Solid electrolyte ceramic sheet density under different sintering conditions.

[0063] Example Seven

[0064] A solid electrolyte surface cleaning method, Na 1.67 Mg 0.67 Al 9.33 GaO 17 After polishing the ceramic sheet, the surface residual polishing residues were removed by ultrasonic acetone, then the ceramic sheet was placed in 0.0001mol / L hydrochloric acid for 1min, after the ceramic sheet surface was wiped dry, it was transferred to the glove box after vacuum heat treatment at 900℃ for 1h.

[0065] Figure 9 Na 1.67 Mg 0.67 Al9.33 GaO 17 Ceramic electrolyte pellet and N1s profile after acid treatment and vacuum heat treatment and N1s alone, Na 1s and Na 1s profile.

[0066] Example Eight

[0067] A method of in-situ alloying of sodium metal with solid electrolyte. Two identical fresh Na disks of 10 mm diameter were hand pressed against each other on Na metal 1.67 Mg 0.67 Al 10.33 O 17 Both sides of the ceramic pellet were then placed on a hot plate set to 50 °C and the Na disk on one side of the ceramic pellet was ultrasonically welded for 2 min using a hand-held ultrasonic machine. Foam nickel was then placed on both sides as a current collector. The entire assembly was then encapsulated in a 2032 coin cell.

[0068] Figure 10 Na metal and solid electrolyte after ultrasonic welding. The Na metal is seen to be in direct contact with the electrolyte. 1.67 Mg 0.67 Al 10.33 O 17 STEM and EDS images of the interface of the coin cell assembled with the ceramic pellet after cycling. Deposition of Mg on the side of the Na electrode is shown.

[0069] Example Nine

[0070] A method of in-situ alloying of sodium metal with solid electrolyte. Two identical fresh Na disks of 10 mm diameter were hand pressed against each other on Na metal 1.67 Mg 0.67 Al 9.33 GaO 17 Both sides of the ceramic pellet were then placed on a hot plate set to 50 °C and the Na disk on one side of the ceramic pellet was ultrasonically welded for 2 min using a hand-held ultrasonic machine. Foam nickel was then placed on both sides as a current collector. The entire assembly was then encapsulated in a 2032 coin cell.

[0071] Figure 11 Na metal and solid electrolyte after ultrasonic welding. The Na metal is seen to be in direct contact with the electrolyte. 1.67 Mg 0.67 Al 9.33 GaO 17 SEM and line EDS images of the Na interface of the ceramic pellet. Deposition of Ga from the electrolyte to form Na-Ga alloy in-situ is seen.

[0072] Figure 12 Na metal and solid electrolyte after ultrasonic welding. The Na metal is seen to be in direct contact with the electrolyte. 1.67 Mg 0.67 Al 9.33 GaO 17STEM and EDS images of the interface of the ceramic coin cell after cycling. It can be clearly seen that Na-Ga alloy formed on the Na electrode side.

[0073] Figure 13 To utilize Na 1.67 Mg 0.67 Al 9.33 GaO 17 Ceramic coin cell assembled with 0.1 mA / cm 2 Na deposition stripping curves of the ceramic coin cell cycled at different current densities.

[0074] Example Ten

[0075] A solid-state battery assembly method. The cathode used a slurry composed of Na3V2(PO4)3, Super P carbon, and polyvinylidene fluoride (PVDF) in a weight ratio of 80:10:10. N-methyl-2-pyrrolidone (NMP) was used as the solvent for slurry preparation. The slurry was then coated on an aluminum foil and vacuum heated at 120 °C for 24 h. The aluminum foil with Na3V2(PO4)3 active material was then cut into a 10 mm diameter disc with a mass loading of 1-2 mg of active material in the cathode. Subsequently, the Na 1.67 Mg 0.67 Al 9.33 GaO 17 5 uL of liquid electrolyte [1 M NaClO4 in EC / DMC (1 : 1) + 5% FEC] was added on the ceramic disc to ensure good contact of the electrolyte with the ceramic disc. Subsequently, the prepared cathode disc was carefully placed on the ceramic disc with foam nickel as the current collector on both sides. Finally, the whole was encapsulated in a 2032 coin cell.

[0076] Figure 14 To utilize Na 1.67 Mg 0.67 Al 9.33 GaO 17 Rate capability of the ceramic coin cell at 30 °C.

[0077] Example Eleven

[0078] A solid-state battery assembly method. The cathode used a slurry composed of Na3V2(PO4)3, Super P carbon, and polyvinylidene fluoride (PVDF) in a weight ratio of 80:10:10. N-methyl-2-pyrrolidone (NMP) was used as the solvent for slurry preparation. The slurry was then coated on an aluminum foil and vacuum heated at 120 °C for 24 h. The aluminum foil with Na3V2(PO4)3 active material was then cut into a 10 mm diameter disc with a mass loading of 1-2 mg of active material in the cathode. Subsequently, the Na 2Na 1.67 Mg 0.67 Al 9.33 GaO 17 and Na 1.67 Mg 0.67 Al 10.33 O 17 5uL of liquid electrolyte [1M NaClO4 in EC / DMC (1:1) + 5% FEC] was dropped on the ceramic sheet to ensure good contact of electrolyte with the ceramic sheet. Subsequently, the prepared anode sheet was carefully placed on the ceramic sheet with foamed nickel as current collector on both sides. Finally, the whole was encapsulated in a 2032 coin cell.

[0079] Figure 15 To utilize Na 1.67 Mg 0.67 Al 9.33 GaO 17 and Na 1.67 Mg 0.67 Al 10.33 O 17 Ceramic sheet assembled 2032 coin cell at 30℃ with 1C cycling performance. It is demonstrated that the selection of appropriate interfacial alloying elements such as Ga can greatly enhance the cycling performance of the battery.

[0080] It is worth noting that the contents not specifically elaborated in the present application are all prior art and are well known to those skilled in the art.

[0081] Therefore, the present application adopts the improved Na-β"-Al2O3 solid electrolyte, preparation method and application described above, and the interface stability between the Na-β"-Al2O3 solid electrolyte and the sodium anode can be significantly improved by element doping and in-situ alloying technology.

[0082] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application and not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: it can still modify or equivalently replace the technical solutions of the present application, and these modifications or equivalent replacements also cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. Use of an improved Na-β"-Al203 solid electrolyte, characterized in that, The target molecular formula of the improved Na-β"-Al2O3 solid electrolyte is Na 1+y M x Al 10+z O 17 , wherein M is Ga, x is 0-0.67, y is 0-1, and z is 0-1, the surface of the improved Na-β"-Al2O3 solid electrolyte is pretreated before assembling the battery, and then in-situ alloying is performed by heating and ultrasonic welding. The sodium vanadium phosphate, sodium vanadium phosphate or layered TM oxide positive electrode is selected, the electrolyte is dropped on the other side surface of the improved Na-β"-Al2O3 solid electrolyte, the nickel mesh or the elastic sheet is used to assemble the solid sodium battery.

2. Use according to claim 1, characterized in that, The pretreatment is acid pickling or heat treatment; The acid solution used for the acid pickling is a mixture of one or more of dilute hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid, and the acid solution is coated on the surface of the improved Na-β"-Al2O3 solid electrolyte for 10s-1min; The heat treatment temperature is 500-900℃, and the heat treatment time is 1-4 hours.

3. Use according to claim 1, characterized in that, The heating temperature is 50-80℃.

4. Use according to claim 1, characterized in that, The frequency of the ultrasonic welding is 40-50KHz, and the welding time is 30s-2min.

5. An improved method for producing a Na-β"-Al203 solid electrolyte, characterized by, The method comprises the following steps: In step S1, the Na-β"-Al2O3 precursor material is selected, including sodium carbonate, sodium hydroxide, aluminum oxide and aluminum hydroxide; The doping element is selected, including the oxide, carbonate or hydroxide of Ga; According to the target formula Na 1+y M x Al 10+z O 17 The corresponding raw materials are weighed and mixed with the Na-β"-Al2O3 precursor material, and a ball mill is used to uniformly mix the materials, wherein M is Ga, x is 0-0.67, y is 0-1, and z is 0-1. In step S2, the mixed powder is primarily sintered at a temperature of 1200-1500℃ for 2-4h to obtain a preliminary solid electrolyte precursor; In step S3, the powder of the preliminary solid electrolyte precursor after ball milling and drying is pressed to obtain a ceramic green body, and the ceramic green body is placed in a high-temperature furnace for sintering treatment, and after sintering, natural cooling or cooling at a predetermined program control rate is performed.

6. The improved method of producing a Na-β"-Al2O3 solid electrolyte according to claim 5, characterized by, For Ga element doping, Na-β"-Al2O3 and Na-β"-Ga2O3 preliminary solid electrolyte precursor powders are synthesized respectively, and then the two are mixed in a ratio of Na 1.77 Al (11-n) Ga n O 17 and ball-milled and pressed into a ceramic green body, and n is 0-1.

7. The improved method of producing a Na-β"-Al203 solid electrolyte according to claim 5, characterized by, In step S1, the rotation speed of the ball mill is 300-1200r / min, and the ball milling time is 1-12h.

8. The improved method of producing a Na-β"-Al203 solid electrolyte according to claim 6, characterized by, In step S3, the pressure during the pressing is 200-300MPa, and the pressing time is 5-30min.

9. The improved method of producing a Na-β"-Al203 solid electrolyte according to claim 7, characterized by, In step S3, the sintering temperature is 1400-1600℃. 10.An improved Na-β"-Al2O3 solid electrolyte prepared by the preparation method of the improved Na-β"-Al2O3 solid electrolyte according to any one of claims 5-9.

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