Synthesis method of high-performance LATP solid electrolyte powder

Abstract

The invention discloses a high-performance LATP solid electrolyte powder synthesis method, which comprises: mixing a lithium source, a titanium source, a phosphorus source, an aluminum source and urea in a solvent, and carrying out a hydrothermal reaction in a closed space to obtain a solid precursor through separation; and drying and calcining the precursor, and ball-milling to obtain the high-performance LATP solid electrolyte powder. According to the method, a hydrothermal and calcination combined mode is adopted, urea which is low in price and easy to obtain is creatively used as a conditioning agent, and the decomposition reaction of urea in a solution is reversible reaction, so that the pH is flexibly adjusted, rapid hydrolysis of inorganic salt is inhibited, slow hydrolysis of the inorganic salt is guaranteed, and the purpose of uniform distribution and complexation in the solution is achieved; and the LATP powder with high yield, high purity and controllable particle size can be obtained through a simple amplification process.

Description

Technical Field

[0001] The invention relates to the technical field of solid-state lithium batteries, and in particular to a method for synthesizing high-performance LATP solid-state electrolyte powder. Background Art

[0002] With the world's continued attention to new renewable energy, exploring safe and efficient energy storage systems is of great significance for my country to achieve the goals of "carbon neutrality" and "carbon peak" as soon as possible. As the most widely used energy storage device, lithium batteries can effectively alleviate society's over-reliance on non-renewable energy (such as oil and natural gas). And lithium batteries are now widely used in new energy vehicles, energy storage stations, and mobile electronic devices. As society has higher demands on the safety, stability, and energy density of energy storage equipment, traditional liquid lithium batteries are increasingly difficult to meet the above requirements due to the use of flammable organic electrolytes.

[0003] Solid-state lithium batteries can meet the above requirements. Since solid-state lithium batteries do not contain or contain less flammable and unstable organic electrolytes, they are expected to be compatible with positive and negative electrode materials with higher energy density, such as lithium metal negative electrodes and ternary positive electrode materials. Solid electrolytes can be roughly divided into three categories: inorganic solid electrolytes, polymer solid electrolytes and composite solid electrolytes. Among them, inorganic solid electrolytes have become a type of solid electrolyte with great application potential due to their high ionic conductivity and lithium ion transfer number, high stability and good mechanical properties.

[0004] Among many inorganic solid electrolytes, lithium titanium phosphate in NASICON type, Li 1+x Al x Ti 2-x (PO 4 ) 3 (LATP, 0≤x≤0.5) with its high ionic conductivity (10 -5 -10 -3 S cm -1 ), wide electrochemical window, good mechanical stability, low cost, wide range of raw materials and good air stability make it one of the most promising solid electrolytes for commercialization. There have been some reports on LATP solid electrolytes, but the methods reported in these reports have problems such as complex synthesis, high time consumption and low yield.

[0005] For example, CN115557483A discloses a method for preparing LATP electrolyte powder, an electrolyte sheet and an all-solid-state battery. The preparation method is to blend lithium source, aluminum source, titanium source and phosphorus source precursor compounds, mix them with isopropanol, grind, dry and screen, and then calcine them in two stages. After calcination, grind and dry again, and then screen out the mixture powder with a size less than 1 μm to obtain a solid electrolyte powder. The steps are very cumbersome and complicated.

[0006] CN113178615 A ​​discloses a method for preparing a LATP solid electrolyte, comprising the following steps: adding deionized water, NaF and H 2 SO 4 , prepare a mixed aqueous solution, heat it, and add TiOSO 4 solution, NaF solution and H 3 PO 4 Solution, solid-liquid separation, washing and drying the obtained solid to obtain Ti 3 (PO 4 ) 3 Solid powder; in Ti 3 (PO 4 ) 3 Add AlPO to solid powder 4 Solid, Li 3 PO 4 Solid, mixed, sintered, crushed, sieved, LATP solid electrolyte was obtained. But again, this process requires hydrothermal Ti 3 (PO 4 ) 3 Solid powder, then with AlPO 4 Solid, Li 3 PO 4 The solid is mixed, sintered and crushed to obtain the product, which is a complicated process and the particle size of the product is still slightly large. Summary of the invention

[0007] The invention solves the problems of complex LATP synthesis method, low yield, many impurities, uneven product particle size, etc., and proposes a synthesis method of high-performance LATP solid electrolyte powder, which has low raw material cost and short time consumption, greatly reduces the synthesis cost of LATP, and the product particle size is small and uniform.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] A method for synthesizing a high-performance LATP solid electrolyte powder comprises the following steps: mixing a lithium source, a titanium source, a phosphorus source, an aluminum source and urea in a solvent, and subjecting the mixture to a hydrothermal reaction in a closed space to obtain a solid precursor by separation; and drying and calcining the precursor and then ball milling the precursor to obtain the high-performance LATP solid electrolyte powder.

[0010] In view of the problems and shortcomings of the above technologies, the present invention uses a combination of hydrothermal and calcination, innovatively uses cheap and readily available urea as a regulator, aluminum salts, titanium salts, lithium salts and phosphate salts as raw materials, and the decomposition reaction of urea in the solution is a reversible reaction, which can be adjusted according to the environment like a pH stabilizer to produce NH 3The amount of HCl can be adjusted flexibly to inhibit the rapid hydrolysis of inorganic salts and ensure the slow hydrolysis of inorganic salts, so as to achieve the purpose of uniform distribution of complexation in the solution. It is no longer necessary to add ammonia water to inhibit the hydrolysis of inorganic salts. A high-yield, high-purity, and controllable particle size LATP powder can be obtained through a simple scale-up process.

[0011] The lithium source includes LiOH, Li 2 CO 3 、LiNO 3 One or more compounds and hydrates thereof.

[0012] The phosphorus source includes H 3 PO 4 NH 4 H 2 PO 4 NH 4 ) 2 HPO 4 One or more of.

[0013] The titanium source includes (CH 3 CH 2 CHO) 4 Ti、Ti(OCH 2 CH 2 CH 2 CH 3 ) 4 、TiO 2 、Ti(NO 3 ) 4 One or more of;

[0014] The aluminum source includes Al 2 O 3 、Al(OH) 3 、Al(NO 3 ) 3 One or more compounds and hydrates thereof.

[0015] Preferably, the lithium source is LiOH and the phosphorus source is NH 4 H 2 PO 4 , titanium source is (CH 3 CH 2 CHO) 4 Ti, aluminum source is Al(NO 3 ) 3 .

[0016] The proportions of lithium source, phosphorus source, titanium source and aluminum source in step 1 are in accordance with Li 1+x Al x Ti 2-x (PO 4 )3 A stoichiometric ratio where 0<x<0.5.

[0017] The dosage of urea is 1wt%-20wt% of all reaction raw materials;

[0018] The solvent includes one or more of isopropanol, ethanol, water, methanol and butanol; the mass fraction of the solute in the reaction solution is 10-80%.

[0019] The temperature of the hydrothermal reaction is 120-220°C, and the reaction time is 12-36h.

[0020] The calcination temperature is 500-1200°C, and the calcination time is 6-10 hours. The preferred calcination temperature is 800-1000°C.

[0021] The drying temperature is 50-100° C., and the drying time is 2-12 hours.

[0022] The method of the present invention can use a 500mL reactor as a container single reactor for scaled-up industrial production, and the output can reach nearly 100g of LATP powder with a purity higher than 99.5%, and the yield is as high as more than 99%.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention innovatively uses urea as a regulator of the hydrothermal reaction to form a precursor precipitate with the raw material, and there is no need to use an alkali to accurately adjust the pH value of the reaction system. The obtained product has high purity, better crystallinity, higher yield, and more concentrated particle size distribution. In addition, since solid urea is used instead of liquid alkali, it is no longer necessary to add ammonia water to inhibit the hydrolysis of inorganic salts. The decomposition reaction of urea in the solution is a reversible reaction (NH 2 ) 2 CO+2H 2 O===2NH 3 +CO 2 ), can adjust pH like a pH stabilizer, inhibit the rapid hydrolysis of inorganic salts, ensure the slow hydrolysis of inorganic salts to achieve the purpose of uniform complexation in the solution, occupy less volume, so more products can be produced using the same volume of hydrothermal kettle. Compared with the grinding method, this method has the characteristics of simple production equipment, easy to control reaction conditions, and less impurities. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the XRD pattern of LATP prepared in Example 1.

[0026] Figure 2 This is the SEM image of LATP prepared in Example 1.

[0027] Figure 3This is the laser particle size distribution diagram of LATP prepared in Example 1.

[0028] Figure 4 This is the XRD pattern of LATP prepared in Comparative Example 1.

[0029] Figure 5 This is the SEM image of LATP prepared in Comparative Example 1.

[0030] Figure 6 This is the XRD pattern of LATP prepared in Example 2.

[0031] Figure 7 This is the SEM image of LATP prepared in Example 2. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art can make modifications or equivalent substitutions based on the understanding of the technical scheme of the present invention without departing from the spirit and scope of the technical scheme of the present invention, and all should be included in the protection scope of the present invention.

[0033] The raw materials used in the following specific embodiments are all purchased from the market.

[0034] Example 1

[0035] Step 1: Add LiOH (1.5 g), Ti(CH 3 CH 2 CHO) 4 (30.0 mL), Al(NO 3 ) 3 9H 2 O (5.6 g), NH 4 H 2 PO 4 (17.2 g) and urea (10.0 g), urea accounting for 15.5% of all the reaction raw materials, the above mixture was stirred for 10 minutes and then added into a 250 mL reactor and sealed;

[0036] Step 2, placing the above reactor at 190° C. for 12 hours, cooling to room temperature after the reaction is completed, and separating the solid product to obtain a precursor powder;

[0037] Step 3, drying the precursor powder obtained in step 2 at 80° C. in an oven, calcining at 900° C. in an air atmosphere for 5 hours, taking out and grinding at room temperature to obtain LATP powder;

[0038] Step 4, placing the LATP powder obtained in step 3 in a ball mill, and ball milling at 400 rpm for 12 hours to obtain a fine LATP powder solid electrolyte.

[0039] After weighing and calculation, the yield of LATP powder was 19.2g, with a yield of 99.8%. The XRD scanning results were as follows: Figure 1 As shown, SEM scanning electron microscopy Figure 2 As shown in the figure. The XRD scanning results all show the characteristic peaks of LATP, and no characteristic peaks of other impurities, indicating that the sample prepared in Example 1 has a high purity and is almost free of impurities. According to the SEM scanning electron microscope image, the particle size of the sample prepared in Example 1 is 100-200nm, and the particle size is uniform. Laser particle size analysis is shown in the figure. Figure 3 As shown, the size distribution of the samples is around 100 nm.

[0040] Comparative Example 1

[0041] Step 1: Add LiOH (1.5 g) and NH 4 H 2 PO 4 (17.2 g), stirring was continued for 0.5 h to prepare a uniform solution A; (CH 3 CH 2 CHO) 4 Ti (30.0 mL) and Al (NO 3 ) 3 9H 2 O (5.6 g) and continued stirring for 0.5 h, and added ammonia water to adjust the solution pH to 10 to prepare a precursor mixed solution.

[0042] Step 2, placing the precursor mixed solution in a 250 mL reactor, reacting at 190° C. for 24 h, and performing solid-liquid separation after the reaction to obtain a precursor powder;

[0043] Step 3, drying the precursor powder obtained in step 2 at 80°C, calcining at 900°C for 6h in air atmosphere, and taking out the LATP solid electrolyte with a yield of 19.1g and a yield of 99.0%. The product XRD is as follows Figure 4 As shown, it can be seen that there are impurities in the XRD test; the microscopic morphology is as follows Figure 5 As shown in the SEM image, the particle agglomeration problem is also seen. In addition, due to the cost of ammonia, the risk is high. Example 2 Scale-up reaction

[0044] Step 1: Add LiOH (7.5 g), Ti(CH 3 CH 2 CHO) 4 (120mL), Al(NO3 ) 3 9H 2 O (28.0 g), NH 4 H 2 PO 4 (86.0 g) and urea (50.0 g), the mixture was stirred for 10 minutes and then added into a 500 mL reactor and sealed;

[0045] Step 2, placing the above reactor at 190° C. for 12 hours, cooling to room temperature after the reaction is completed, and separating the solid product to obtain a precursor powder;

[0046] Step 3, drying the precursor powder obtained in step 2 at 80° C. in an oven, calcining at 900° C. in an air atmosphere for 5 hours, taking it out and grinding it to obtain LATP powder;

[0047] Step 4, placing the LATP powder obtained in step 3 in a ball mill, and ball milling at 400 rpm for 12 hours to obtain a fine LATP powder solid electrolyte.

[0048] The yield of LATP powder obtained by weighing and calculation is 92.0g, with a yield of 99.7%. The XRD scanning results are as follows: Figure 6 As shown, SEM scanning electron microscopy Figure 7 The XRD scanning results all show the characteristic peaks of LATP, and no characteristic peaks of other impurities, indicating that the sample prepared in Example 2 has a high purity and is almost free of impurities. According to the SEM scanning electron microscope image, the particle size of the sample prepared in Example 2 is 100-300nm, and the particle size is uniform.

Claims

1. A method for synthesizing high-performance LATP solid electrolyte powder, characterized in that: The method comprises the following steps: mixing a lithium source, a titanium source, a phosphorus source, an aluminum source and urea in a solvent, and subjecting the mixture to a hydrothermal reaction in a closed space to separation to obtain a solid precursor; and drying and calcining the precursor and then ball milling the precursor to obtain the high-performance LATP solid electrolyte powder.

2. The method for synthesizing high-performance LATP solid electrolyte powder according to claim 1, characterized in that: The lithium source includes one or more compounds of LiOH, Li2CO3, LiNO3 and hydrates thereof.

3. The method for synthesizing high-performance LATP solid electrolyte powder according to claim 1, characterized in that: The phosphorus source includes one or more of H3PO4, NH4H2PO4, (NH4)2HPO4.

4. The method for synthesizing high-performance LATP solid electrolyte powder according to claim 1, characterized in that: The titanium source includes one or more of (CH3CH2CHO)4Ti, Ti(OCH2CH2CH2CH3)4, TiO2, and Ti(NO3)4.

5. The method for synthesizing high-performance LATP solid electrolyte powder according to claim 1, characterized in that: The aluminum source includes one or more compounds of Al2O3, Al(OH)3, Al(NO3)3 and their hydrates.

6. The method for synthesizing high-performance LATP solid electrolyte powder according to claim 1, characterized in that: The proportions of lithium source, phosphorus source, titanium source and aluminum source in step 1 are in accordance with Li 1+x Al x Ti 2-x The stoichiometric ratio of (PO4)3, where 0<x<0.

5.

7. The method for synthesizing high-performance LATP solid electrolyte powder according to claim 1, characterized in that: The dosage of urea is 1wt%-20wt% of all the reaction raw materials.

8. The method for synthesizing high-performance LATP solid electrolyte powder according to claim 1, characterized in that: The solvent includes one or more of isopropanol, ethanol, water, methanol and butanol; the mass fraction of the solute in the reaction solution is 10-80%.

9. The method for synthesizing high-performance LATP solid electrolyte powder according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 120-220°C, and the reaction time is 12-36h.

10. The method for synthesizing high-performance LATP solid electrolyte powder according to claim 1, characterized in that: The calcination temperature is 500-1200°C, and the calcination time is 6-10h.

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