Process for the preparation of high hardness oxide sodium ion solid state electrolyte

Abstract

The application belongs to the technical field of sodium battery, and particularly relates to a high-hardness oxide sodium ion solid electrolyte preparation process. The high-hardness oxide sodium ion solid electrolyte preparation process comprises the following steps: (1) mixing NaNO3, La2O3 and ZrO2, then performing wet ball milling, and then performing vacuum drying to obtain a mixed powder; (2) performing heat treatment on the mixed powder, and then performing sieving to obtain an electrolyte powder; (3) adding beta-Al2O3 into the electrolyte powder and uniformly grinding; (4) uniformly mixing a binder in the electrolyte mixed powder, then laying the electrolyte mixed powder in a tabletting die, and then performing tabletting by using a tabletting machine; and (5) finally performing calcination to obtain the high-hardness oxide sodium ion solid electrolyte. The preparation process is low in cost and simple in method, improves the forming degree of the solid electrolyte, and improves the forming degree and hardness of the solid electrolyte.

Description

Technical Field

[0001] This invention belongs to the field of sodium battery technology, specifically relating to the preparation process of high-hardness oxide sodium-ion solid electrolyte. Background Technology

[0002] Solid-state electrolytes represent a future trend in sodium-ion battery development. Recent research has revealed that sodium-ion solid-state batteries possess numerous advantages over lithium-ion solid-state batteries, particularly in terms of raw material costs. An increasing number of sodium-ion battery companies both domestically and internationally are considering solid-state battery technology as their next-generation technology reserve. Compared to liquid batteries, solid-state sodium batteries offer higher rate performance, greater safety and reliability, larger energy storage, and a higher safety factor. Furthermore, because solid-state electrolytes are non-flammable, non-corrosive, non-volatile, and leak-proof, they will not ignite even at high temperatures, thus ensuring higher safety. Cars equipped with all-solid-state sodium batteries will experience increased driving range, faster charging speeds, and a significantly reduced risk of spontaneous combustion.

[0003] Patent CN112174661A discloses a sodium-lanthanum-zirconium composite solid electrolyte and its preparation method, with the molecular formula Na. 0.5+x La 0.5-x ZrO 3-δ The method is as follows: (1) Prepare sodium carbonate powder, zirconium oxide powder and lanthanum oxide powder and mix them in a molar ratio of Na:Zr:Ce=(0.5+x):(0.5-x):1; (2) Use water or anhydrous ethanol as the ball milling medium to ball mill the mixed powder and then dry it; (3) Press it into shape, calcine it at 1000~1400℃ for 1~10h, and cool it with the furnace; (4) Grind it to a particle size of less than 200 mesh, press it into shape again, sinter it at 1450~1650℃ for 2~10h, and cool it with the furnace. In (2), the drying time is long when using water as a solvent, which wastes energy. In (4), 200 mesh is relatively coarse, which is not conducive to the success rate of tableting and the strength value. In (4), the sintering temperature of 1450~1650℃ is too high, which is not conducive to saving costs. The purpose of the final sintering is to eliminate stress. The temperature is too high and may destroy the material structure.

[0004] Solid-state electrolytes play a crucial role in the overall performance of solid-state batteries. The preparation process mainly involves ball milling and heat treatment, followed by pressing the resulting solid-state electrolyte powder into tablets using a manual tablet press. However, solid-state electrolytes prepared using existing technologies exhibit poor hardness and formability. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a process for preparing high-hardness sodium oxide ion solid electrolytes. This method is simple, low-cost, and significantly improves the formability and hardness of solid electrolytes.

[0006] The high-hardness oxide sodium ion solid electrolyte preparation process of the present invention includes the following steps:

[0007] (1) NaNO3, La2O3 and ZrO2 are mixed and then wet ball milled, and then vacuum dried to obtain mixed powder;

[0008] (2) The mixed powder is heat-treated and sieved to obtain electrolyte powder;

[0009] (3) Add β-Al2O3 to the electrolyte powder and grind it evenly and thoroughly;

[0010] (4) Add binder to electrolyte powder and mix evenly, then spread it evenly in tableting mold and compress it into tablets using a tableting machine;

[0011] (5) Finally, calcination is performed to obtain a high-hardness oxide sodium ion solid electrolyte.

[0012] In step (1), the molar ratio of NaNO3, La2O3, and ZrO2 is (8-12):(1-4):(1-3). NaNO3 is in excess by 10% to compensate for the amount of Na volatilized at high temperature.

[0013] The wet ball milling in step (1) is carried out using a planetary ball mill, with agate balls as grinding balls, a ball-to-material mass ratio of (10-15):1, a ball milling speed of 300-350 rpm, and a ball milling time of 6-10 h. Ethanol is used as a solvent during ball milling, and the amount of ethanol used is 10-20% of the total mass of NaNO3, La2O3, and ZrO2. The vacuum drying temperature is 60-80℃, and the drying time is 8-12 h.

[0014] The sieving process in step (2) is performed using an 800-1000 mesh sieve.

[0015] The heat treatment in step (2) involves heating to 800-950℃ at a rate of 1-3℃ / min and holding at that temperature for 10-12 hours.

[0016] The amount of β-Al2O3 added in step (3) is 1-2.5% of the mass of the electrolyte powder.

[0017] The pressure for tablet compression in step (4) is 500-600 MPa, and the holding time is 1-3 min.

[0018] The amount of binder added in step (4) is 0.5-1% of the mass of the electrolyte powder.

[0019] The binder in step (4) is a mixture of sodium carboxymethyl cellulose and terpineol in a mass ratio of 1:(0.1-0.2). Sodium carboxymethyl cellulose and solid electrolyte powder are ground together, and then terpineol is added dropwise and stirred evenly.

[0020] The final calcination temperature in step (5) is 1100-1250℃, and the molecular formula of the prepared sodium oxide ion solid electrolyte sheet is Na7La. 3-x Al x Zr2O 12 Where x is 1-2. Na7La 3-x Al x Zr2O 12 It belongs to the cubic crystal system, space group Ia-3d. La ions occupy tetrahedral positions. When Al ions enter the tetrahedral structure, some occupy La sites, and some La... 3+ By Al 3+ Replacement.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) The high-strength oxide sodium ion solid electrolyte preparation process of the present invention uses sodium carboxymethyl cellulose as a binder to prepare solid electrolyte with good formability, which improves the strength of solid electrolyte sheet and greatly reduces the thickness of solid electrolyte, which helps to improve the success rate of solid electrolyte sheet pressing and provides the possibility for further preparation of high energy density all-solid-state batteries.

[0023] (2) The present invention performs vacuum drying after wet ball milling in step (1). Compared with the non-vacuum environment, the obtained powder has a smaller particle size and no particle feel. Powder dried in a non-vacuum environment is prone to agglomeration and needs to be ground twice before it can be sieved.

[0024] (3) The addition of β-Al2O3 in this invention can effectively improve the hardness of solid electrolyte and reduce surface wrinkles of electrolyte. Detailed Implementation

[0025] The present invention will be further described below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto.

[0026] Unless otherwise specified, all raw materials used in the examples were commercially available.

[0027] Example 1

[0028] The preparation process of the high-hardness oxide sodium ion solid electrolyte includes the following steps:

[0029] (1) NaNO3, La2O3 and ZrO2 were mixed in a molar ratio of 8:3:2, with NaNO3 in excess by 10% to compensate for the amount of Na volatilized at high temperature; after mixing, the mixture was placed in a planetary ball mill with agate balls as grinding balls at a ball-to-material mass ratio of 10:1, and ethanol of 10% of the total mass of NaNO3, La2O3 and ZrO2 was added for wet ball milling at a speed of 300 rpm for 6 hours; after ball milling, the mixture was dried in a vacuum drying oven at 60°C for 8 hours to obtain a white powder.

[0030] (2) Place the powder in a muffle furnace, set the heating rate to 1℃ / min, heat to 950℃, keep it at that temperature for 8 hours, cool it naturally to room temperature, and sieve it to obtain electrolyte powder with a mesh size of less than 1000 mesh.

[0031] (3) Mix β-Al2O3 and electrolyte powder, grind them evenly, and add β-Al2O3 at 1% of the mass of electrolyte powder;

[0032] (4) Take 0.5g of electrolyte powder, add 0.5% of the electrolyte powder mass of sodium hydroxymethyl cellulose and terpineol in a mass ratio of 1:0.1, grind thoroughly and spread evenly in the tablet press mold, press the tablet with 500MPa pressure, hold the pressure for 1min and take it out. The tableting is completed and sodium oxide ion solid electrolyte tablets are obtained.

[0033] (5) The solid electrolyte tablets after compression are calcined at 1200℃ to finally obtain high hardness sodium oxide ion solid electrolyte.

[0034] Example 2

[0035] The preparation process of the high-hardness oxide sodium ion solid electrolyte includes the following steps:

[0036] (1) NaNO3, La2O3 and ZrO2 were mixed in a molar ratio of 9:3:1, with NaNO3 in excess by 10% to compensate for the amount of Na volatilized at high temperature; after mixing, the mixture was placed in a planetary ball mill with agate balls as grinding balls at a ball-to-material mass ratio of 10:1, and ethanol of 12% of the total mass of NaNO3, La2O3 and ZrO2 was added for wet ball milling at a speed of 320 rpm for 8 hours; after ball milling, the mixture was dried in a vacuum drying oven at 70°C for 8 hours to obtain a white powder.

[0037] (2) Place the powder in a muffle furnace, set the heating rate to 2℃ / min, heat to 900℃, keep it at that temperature for 10h, cool it naturally to room temperature, and sieve it to obtain electrolyte powder with a mesh size of less than 900.

[0038] (3) Mix β-Al2O3 and electrolyte powder, grind them evenly, and add β-Al2O3 at 1% of the mass of electrolyte powder;

[0039] (4) Take 0.5g of electrolyte powder, add 0.5% of the electrolyte powder mass of sodium hydroxymethyl cellulose and terpineol in a mass ratio of 1:0.15, grind thoroughly and spread evenly in the tablet press mold, press with 540MPa pressure, hold pressure for 2min and take out, the tableting is completed, and sodium oxide ion solid electrolyte tablets are obtained.

[0040] (5) The solid electrolyte tablets after compression are calcined at 1150℃ to finally obtain high hardness oxide sodium ion solid electrolyte.

[0041] Example 3

[0042] The preparation process of the high-hardness oxide sodium ion solid electrolyte includes the following steps:

[0043] (1) NaNO3, La2O3 and ZrO2 were mixed in a molar ratio of 9:2:2, with NaNO3 in excess by 10% to compensate for the amount of Na volatilized at high temperature; after mixing, the mixture was placed in a planetary ball mill with agate balls as grinding balls at a ball-to-material mass ratio of 12:1, and ethanol accounting for 14% of the total mass of NaNO3, La2O3 and ZrO2 was added for wet ball milling at a speed of 320 rpm for 10 h; after ball milling, the mixture was dried in a vacuum drying oven at 80°C for 8 h to obtain a white powder.

[0044] (2) Place the powder in a muffle furnace, set the heating rate to 3℃ / min, heat to 850℃, hold for 12h, cool naturally to room temperature, and sieve to obtain electrolyte powder with a mesh size of less than 800.

[0045] (3) Mix β-Al2O3 and electrolyte powder, grind them evenly, and add β-Al2O3 at 2% of the mass of electrolyte powder;

[0046] (4) Take 0.5g of electrolyte powder, add 0.8% of the electrolyte powder mass of sodium hydroxymethyl cellulose and terpineol in a mass ratio of 1:0.2, grind thoroughly and spread evenly in the tablet press mold, press the tablet with a pressure of 560MPa, hold the pressure for 3min and take it out. The tableting is completed and sodium oxide ion solid electrolyte tablets are obtained.

[0047] (5) The solid electrolyte tablets after compression are calcined at 1100℃ to finally obtain high hardness sodium oxide ion solid electrolyte.

[0048] Example 4

[0049] The preparation process of the high-hardness oxide sodium ion solid electrolyte includes the following steps:

[0050] (1) NaNO3, La2O3 and ZrO2 were mixed in a molar ratio of 10:2:1, with NaNO3 in excess by 10% to compensate for the amount of Na volatilized at high temperature; after mixing, the mixture was placed in a planetary ball mill with agate balls as grinding balls at a ball-to-material mass ratio of 15:1, and ethanol of 16% of the total mass of NaNO3, La2O3 and ZrO2 was added for wet ball milling at a speed of 350 rpm for 10 h; after ball milling, the mixture was dried in a vacuum drying oven at 70 °C for 12 h to obtain a white powder.

[0051] (2) Place the powder in a muffle furnace, set the heating rate to 3℃ / min, heat to 800℃, keep it at 800℃ for 12h, cool it naturally to room temperature, and sieve it to obtain electrolyte powder with a mesh size of less than 800.

[0052] (3) Mix β-Al2O3 and electrolyte powder, grind them evenly, and add β-Al2O3 at 2% of the mass of electrolyte powder;

[0053] (4) Take 0.5g of electrolyte powder, add 0.8% of the electrolyte powder mass of sodium hydroxymethyl cellulose and terpineol in a mass ratio of 1:0.2, grind thoroughly and spread evenly in the tablet press mold, press the tablet with a pressure of 580MPa, hold the pressure for 3min and take it out. The tableting is completed and sodium oxide ion solid electrolyte tablets are obtained.

[0054] (5) The solid electrolyte tablets after compression are calcined at 1200℃ to finally obtain high hardness sodium oxide ion solid electrolyte.

[0055] Example 5

[0056] The preparation process of the high-hardness oxide sodium ion solid electrolyte includes the following steps:

[0057] (1) NaNO3, La2O3 and ZrO2 were mixed in a molar ratio of 10:1.8:1.2, with NaNO3 in excess by 10% to compensate for the amount of Na volatilized at high temperature; after mixing, the mixture was placed in a planetary ball mill with agate balls as grinding balls at a ball-to-material mass ratio of 12:1, and ethanol accounting for 18% of the total mass of NaNO3, La2O3 and ZrO2 was added for wet ball milling at a speed of 350 rpm for 10 h; after ball milling, the mixture was dried in a vacuum drying oven at 60 °C for 10 h to obtain a white powder.

[0058] (2) Place the powder in a muffle furnace, set the heating rate to 3℃ / min, heat to 800℃, hold for 12h, cool naturally to room temperature, and sieve to obtain electrolyte powder with a mesh size of less than 900.

[0059] (3) Mix β-Al2O3 and electrolyte powder, grind them evenly, and add β-Al2O3 at 2.5% of the mass of electrolyte powder;

[0060] (4) Take 0.5g of electrolyte powder, add 1% of the electrolyte powder mass of sodium hydroxymethyl cellulose and terpineol in a mass ratio of 1:0.2, grind thoroughly and spread evenly in the tablet press mold, press the tablet with 600MPa pressure, hold the pressure for 3min and take it out. The tableting is completed and sodium oxide ion solid electrolyte tablets are obtained.

[0061] (5) The solid electrolyte tablets after compression are calcined at 1100℃ to finally obtain high hardness sodium oxide ion solid electrolyte.

[0062] Example 6

[0063] The preparation process of the high-hardness oxide sodium ion solid electrolyte includes the following steps:

[0064] (1) NaNO3, La2O3 and ZrO2 were mixed in a molar ratio of 9:1.8:2.2, with NaNO3 in excess by 10% to compensate for the amount of Na volatilized at high temperature; after mixing, the mixture was placed in a planetary ball mill with agate balls as grinding balls at a ball-to-material mass ratio of 12:1, and ethanol of 20% of the total mass of NaNO3, La2O3 and ZrO2 was added for wet ball milling at a speed of 350 rpm for 10 h; after ball milling, the mixture was dried in a vacuum drying oven at 60 °C for 12 h to obtain a white powder.

[0065] (2) Place the powder in a muffle furnace, set the heating rate to 3℃ / min, heat to 800℃, hold for 12h, cool naturally to room temperature, and sieve to obtain electrolyte powder with a mesh size of less than 900.

[0066] (3) Mix β-Al2O3 and electrolyte powder, grind them evenly, and add β-Al2O3 at 2.5% of the mass of electrolyte powder;

[0067] (4) Take 0.5g of electrolyte powder, add 1% of the electrolyte powder mass of sodium hydroxymethyl cellulose and terpineol in a mass ratio of 1:0.2, grind thoroughly and spread evenly in the tablet press mold, press the tablet with 600MPa pressure, hold the pressure for 2min and take it out. The tableting is completed and sodium oxide ion solid electrolyte tablets are obtained.

[0068] (5) The solid electrolyte tablets after compression are calcined at 1150℃ to finally obtain high hardness oxide sodium ion solid electrolyte.

[0069] Comparative Example 1

[0070] The only difference between this comparative example and Example 1 is that the drying in step (1) is not carried out in a vacuum drying oven, but in a non-vacuum environment. The resulting powder agglomerates with a larger particle size and a noticeable granular texture.

[0071] Comparative Example 2

[0072] The only difference between this comparative example and Example 1 is that no binder is added when tableting in step (3). The product obtained after tableting is prone to cracking and has low moldability.

[0073] Comparative Example 3

[0074] The only difference between this comparative example and Example 1 is that β-Al2O3 is not added in step (3). Without β-Al2O3, the electrolyte surface wrinkles and is not hard.

[0075] Comparative Example 4

[0076] The only difference between this comparative example and Example 1 is that, during the tableting process in step (3), terpineol was removed from the binder and sodium hydroxymethyl cellulose was used to replenish the original terpineol content. The resulting tableted product is prone to cracking and has low formability.

[0077] The compressive strength of solid electrolytes was tested using Vickers hardness, and the results are shown in Table 1 below:

[0078]

Claims

1. A process for preparing a high-hardness oxide sodium-ion solid electrolyte, characterized in that: Includes the following steps: (1) NaNO3, La2O3 and ZrO2 are mixed and then wet ball milled, and then vacuum dried to obtain mixed powder; (2) The mixed powder is heat-treated and sieved to obtain electrolyte powder; (3) Add β-Al2O3 to the electrolyte powder and grind it evenly; (4) Add binder to electrolyte powder and mix evenly, then spread it evenly in tableting mold and compress it into tablets using a tableting machine; (5) Finally, calcination is performed to obtain a high-hardness oxide sodium ion solid electrolyte.

2. The preparation process of high-hardness oxide sodium ion solid electrolyte according to claim 1, characterized in that: In step (1), the molar ratio of NaNO3, La2O3 and ZrO2 is (8-12):(1-4):(1-3).

3. The preparation process of high-hardness oxide sodium ion solid electrolyte according to claim 1, characterized in that: The wet ball milling in step (1) is carried out using a planetary ball mill, with agate balls as grinding balls, a ball-to-material mass ratio of (10-15):1, a ball milling speed of 300-350 rpm, and a ball milling time of 6-10 h. Ethanol is used as a solvent during ball milling, and the amount of ethanol used is 10-20% of the total mass of NaNO3, La2O3, and ZrO2. The vacuum drying temperature is 60-80℃, and the drying time is 8-12 h.

4. The preparation process of high-hardness oxide sodium ion solid electrolyte according to claim 1, characterized in that: The sieving process in step (2) is performed using an 800-1000 mesh sieve.

5. The preparation process of high-hardness oxide sodium ion solid electrolyte according to claim 1, characterized in that: The heat treatment in step (2) involves heating to 800-950℃ at a rate of 1-3℃ / min and holding at that temperature for 10-12 hours.

6. The preparation process of high-hardness oxide sodium ion solid electrolyte according to claim 1, characterized in that: The amount of β-Al2O3 added in step (3) is 1-2.5% of the mass of the electrolyte powder.

7. The preparation process of high-hardness oxide sodium ion solid electrolyte according to claim 1, characterized in that: The pressure for tablet compression in step (4) is 500-600 MPa, and the holding time is 1-3 min.

8. The preparation process of high-hardness oxide sodium ion solid electrolyte according to claim 1, characterized in that: The amount of binder added in step (4) is 0.5-1% of the mass of the electrolyte powder.

9. The preparation process of high-hardness oxide sodium ion solid electrolyte according to claim 1, characterized in that: The binder in step (4) is a mixture of sodium carboxymethyl cellulose and terpineol in a mass ratio of 1:(0.1-0.2). Sodium carboxymethyl cellulose and solid electrolyte powder are ground together, and then terpineol is added dropwise and stirred evenly.

10. The preparation process of high-hardness oxide sodium ion solid electrolyte according to claim 1, characterized in that: The final calcination temperature in step (5) is 1100-1250℃.

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