Preparation method of low-cost LATP solid electrolyte

Abstract

The invention relates to the technical field of new energy, and discloses a low-cost LATP solid electrolyte preparation method, which comprises: mixing a lithium source, an aluminum source, a titanium source, a phosphorus source, a wet grinding solvent and PVP, carrying out primary ball milling, drying, calcining, mixing the calcined powder with the wet grinding solvent, carrying out secondary ball milling, and drying to obtain the LATP solid electrolyte, the mass ratio of the PVP to the solid material is 1: (3-5). The LATP precursor mixed powder is directly prepared by performing simple physical ball-milling dispersion on the precursor, the wet-milling solvent and the dispersing agent through a wet-milling method, so that the high-temperature and high-pressure environments for treating the precursor in the traditional preparation method are avoided, and the calcined powder is subjected to ball-milling again, so that the LATP particles are uniformly dispersed and are smaller in particle size. The method has the advantages of high yield, low equipment requirement and high product purity, and is very suitable for large-batch process production.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to a method for preparing a low-cost LATP solid electrolyte. Background Art

[0002] Lithium-ion batteries are widely used energy storage and conversion devices, but the frequent safety accidents of lithium-ion batteries have caused people's concerns. At present, lithium-ion batteries have gradually failed to meet people's demand for high energy density, so many companies and research institutions have conducted in-depth research on solid-state batteries using solid electrolytes. Solid-state batteries use solid electrolytes to replace traditional flammable liquid electrolytes, reducing the risk of safety accidents while achieving higher energy density. The core of solid-state electrolytes is solid electrolytes. The efficient and low-cost preparation of solid-state electrolytes has always been one of the areas actively explored by all walks of life.

[0003] LATP (full name lithium aluminum titanium phosphate, Li 1+x Al x Ti 2-x (PO4)3, 0≤x≤0.5) is a key material that has attracted much attention in the field of new energy, especially in solid-state battery technology. As a type of solid electrolyte, LATP has significant advantages in improving battery performance, safety and stability due to its unique physical and chemical properties. LATP is an inorganic non-metallic material, and its internal ion arrangement and bonding method give it good ion conductivity. In solid-state batteries, LATP solid-state electrolytes can replace traditional liquid electrolytes, thereby fundamentally solving safety risks such as battery leakage and fire. Compared with traditional liquid electrolytes, LATP solid-state electrolytes have higher safety and stability, and can significantly improve the battery's charging and discharging efficiency and cycle life.

[0004] In recent years, with the continuous development of new energy technologies and the continuous growth of market demand, the research and development of LATP solid electrolytes has gradually received attention. Many companies and research institutions are actively investing in research and development to promote the commercial application of LATP solid electrolytes. Academia and industry have also conducted a lot of research on the preparation process and performance optimization of LATP solid electrolytes. For example, the ionic conductivity and stability of LATP can be effectively improved by doping modification, optimizing synthesis methods and other means.

[0005] For example, CN 113178615 A ​​discloses a method for preparing a LATP solid electrolyte, which relates to the technical field of preparing solid electrolytes for lithium-ion secondary batteries. The preparation method comprises the following steps: S1. adding TiOSO4 to deionized water, mixing, preparing a TiOSO4 aqueous solution, adjusting the pH value, preparing a TiOSO4 aqueous solution after adjusting the pH value, and setting it aside; S2. adding NaF to deionized water, preparing a NaF aqueous solution, and setting it aside; S3. adding H3PO4 to deionized water, preparing an H3PO4 aqueous solution, and setting it aside; S4. adding deionized water, NaF and H2SO4 to a reactor, preparing a mixed bottom aqueous solution, heating, adding TiOSO4 solution, NaF solution and H3PO4 solution to the reactor at the same time, separating the solid from the liquid, washing and drying the prepared solid, and preparing a Ti3(PO4)3 solid powder; S5. adding AlPO4 solid and Li3PO4 solid to the Ti3(PO4)3 solid powder, mixing, sintering, crushing and sieving to prepare a LATP solid electrolyte.

[0006] CN117766849A discloses a method for preparing a high-performance LATP solid electrolyte, comprising the following steps: step 1, mixing a lithium source, a phosphorus source, a titanium source and an aluminum source in a solvent, adding ammonia water to adjust to alkalinity, and obtaining a precursor mixed solution; step 2, placing the precursor mixed solution in a reactor for high-pressure reaction, and separating to obtain a precursor powder; step 3, drying the precursor powder and calcining it to obtain the high-performance LATP solid electrolyte.

[0007] However, the current preparation methods of high-purity and high-ionic conductivity LATP are relatively complicated, and the cost of raw materials is relatively high. Various preparation methods include low-temperature oxidation of LATP precursors, short-term high-temperature sintering of precursors in a protective atmosphere, low-temperature oxidation decarbonization, and dynamic high-temperature sintering decarbonization, or designing high-temperature and high-pressure hydrothermal methods, which increase the difficulty and danger of operations in the production process. Summary of the invention

[0008] In order to reduce the difficulty of LATP production, simplify the production process, and reduce the production cost of LATP, the present invention provides a simple and low-cost LATP production process, and the prepared LATP material has high ion conductivity and more uniform particle size.

[0009] To achieve the above object, the technical solution adopted by the present invention is:

[0010] A method for preparing a low-cost LATP solid electrolyte, characterized in that it comprises the steps of:

[0011] The lithium source, aluminum source, titanium source, phosphorus source, wet grinding solvent and PVP are mixed and ball milled once, dried and calcined, and the calcined powder is mixed with the wet grinding solvent for a second ball milling, and dried to obtain the LATP solid electrolyte.

[0012] The wet grinding solvent is isopropanol and / or ethanol; the lithium source, aluminum source and phosphorus source constitute a solid material, and the mass ratio of the PVP to the solid material is 1:3-5.

[0013] The present invention adopts a one-step wet milling method to process precursors such as lithium source, aluminum source, titanium source and phosphorus source, ensuring that the raw materials are dispersed and mixed uniformly through the simplest physical ball milling, and eliminating the high temperature and high pressure environment for the treatment of the precursors in the traditional preparation method, and has the characteristics of high efficiency. The titanium source is hydrolyzed and condensed by the wet milling solvent, so that the titanium source is dispersed more evenly, and the addition of the dispersant PVP promotes a more uniform dispersion between the raw materials, the synthesis efficiency is higher, the space utilization rate of the ball mill is improved, and the single tank single output is increased. In addition, through secondary ball milling, the particles that were originally agglomerated due to sintering are dispersed into LATP particles of smaller particle size through physical separation.

[0014] The lithium source includes one or more compounds selected from the group consisting of LiOH, Li2CO3, CH3COOLi, LiNO3, and Li3PO4, and their hydrates; the aluminum source includes one or more compounds selected from the group consisting of Al2O3, Al(OH)3, and Al2(CO3)3, and their hydrates; the titanium source includes one or more selected from the group consisting of (CH3CH2CHO)4Ti, Ti(OCH2CH2CH2CH3)4, TiO2, and Ti(NO3)4; the phosphorus source includes one or more selected from the group consisting of H4H2PO4, (NH4)2HPO4, and Li3PO4.

[0015] Preferably, the lithium source is LiOH, the phosphorus source is NH4H2PO4, the titanium source is Ti(OCH2CH2CH2CH3)4, and the aluminum source is Al(NO3)3.

[0016] The titanium source is liquid tetrabutyl titanate, and when isopropanol is used as the wet grinding solvent, its hydrolysis and condensation can be promoted, the amount of isopropanol used can be reduced, the space utilization rate of the ball mill can be improved, and the single-tank single-time output can be increased.

[0017] The mass ratio of the wet grinding solvent to the solid material in the first ball milling is 1:1-2:1; the mass ratio of the ball to the solid material is 8-15:1;

[0018] The rotation speed of the first ball milling is 400-500 rpm, preferably 500 rpm, with each rotation of 10-20 min and a pause of 10-20 min, and the total ball milling time is 36-48 h;

[0019] The mass ratio of wet grinding solvent to material in the secondary ball milling is 2:1-5:1; the mass ratio of ball to material is 8-15:1;

[0020] The secondary ball milling has a rotation speed of 400-500 rpm, preferably 500 rpm, with each rotation of 10-20 min and a pause of 10-20 min, and the total ball milling time is 8-15 h;

[0021] The drying temperature is 50-80°C, and the drying time is 10-12 hours.

[0022] The calcination temperature is 700-900° C., preferably 900° C., and the calcination time is 5-8 hours, preferably 6 hours.

[0023] This method can use a 1500mL ball mill as a container, and the output of a single mill can reach nearly 200g of high-purity LATP powder, with high yield and high efficiency.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] In the present invention, the precursor, wet grinding solvent and dispersant are dispersed by simple physical ball milling by wet grinding method to directly obtain LATP precursor mixed powder, which eliminates the high temperature and high pressure environment for the treatment of the precursor in the traditional preparation method, and the preparation method is simple and efficient; the powder after calcination is ball milled again to make the LATP particles dispersed evenly and the particle size smaller. The method has high output, low equipment requirements, high product purity, and is very suitable for large-scale process production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the XRD pattern of LATP prepared in Example 1.

[0027] Figure 2 This is the SEM image of LATP prepared in Example 1.

[0028] Figure 3 This is the XRD pattern of LATP prepared in Example 2.

[0029] Figure 4 This is the SEM image of LATP prepared in Example 2.

[0030] Figure 5 This is the XRD pattern of LATP prepared in Comparative Example 1.

[0031] Figure 6 This is the SEM image of LATP prepared in Comparative Example 1.

[0032] Figure 7 This is the XRD pattern of LATP prepared in Comparative Example 2.

[0033] Figure 8 This is the SEM image of LATP prepared in Comparative Example 2. DETAILED DESCRIPTION

[0034] 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.

[0035] The raw materials used in the following specific embodiments are all purchased from the market.

[0036] Example 1

[0037] Step 1, place 15.04 g LiOH, 56.28 g Al(NO3)3·9H2O, 300 mL tetrabutyl titanate and 172.54 g NH4H2PO4 in a 1.5 L ball mill, add 900 g ball mill zirconium beads, 250 mL isopropanol and 60 g PVP.

[0038] Step 2: ball mill the mixture at 450 rpm for 36 h (15 min pause per rotation)

[0039] Step 3, the ball-milled precursor is placed in a 60° C. oven for 12 h for thorough drying;

[0040] Step 4, placing the dried precursor in a box furnace, heating it to 900° C. at a heating rate of 5° C. per minute for calcination, and the calcination time is 6 hours to obtain nano-scale LATP powder;

[0041] Step 5, placing the LATP powder after high-temperature sintering in a ball mill, loading ball mill zirconium beads according to the ball-to-material mass ratio of 10:1; the ratio (mass ratio) of wet grinding solvent to LATP material is 4:1; the ball milling speed is 400rpm for ball milling; the ball milling time is 10h (15min pause for each rotation), and after ball milling, it is dried at 60°C to obtain the final LATP solid electrolyte powder.

[0042] The XRD patterns of the prepared LATP solid electrolyte powder are as follows: Figure 1 As shown in the SEM microstructure Figure 2 As shown, it can be seen that the product has high purity, few impurities, and the powder particle size is small and evenly distributed.

[0043] Example 2

[0044] Step 1, place 7.52g LiOH, 28.14g Al(NO3)3·9H2O, 150mL tetrabutyl titanate and 86.27g NH4H2PO4 in a 1.5L ball mill, add 900g ball mill zirconium beads, 125mL isopropanol and 30g PVP.

[0045] Step 2: ball mill the mixture at 450 rpm for 36 h (15 min pause per rotation)

[0046] Step 3, the ball-milled precursor is placed in a 60° C. oven for 12 h for thorough drying;

[0047] Step 4: Place the dried precursor in a box furnace and heat it to 900°C at a heating rate of 5°C per minute for 6 hours to obtain nano-LATP powder.

[0048] Step 5, placing the LATP powder after high-temperature sintering in a ball mill, loading ball mill zirconium beads according to the ball-to-material mass ratio of 10:1; the ratio (mass ratio) of wet grinding solvent to LATP material is 4:1; the ball milling speed is 400rpm for ball milling; the ball milling time is 10h (15min pause for each rotation), and after ball milling, it is dried at 60°C to obtain the final LATP solid electrolyte powder.

[0049] The XRD patterns of the prepared LATP solid electrolyte powder are as follows: Figure 3 As shown in the SEM microstructure Figure 4 As shown, it can be seen that the product has high purity, few impurities, small particle size and high size uniformity.

[0050] Comparative Example 1

[0051] Step 1, place 15.04 g LiOH, 56.28 g Al(NO3)3·9H2O, 300 mL tetrabutyl titanate and 172.54 g NH4H2PO4 in a 1.5 L ball mill, add 900 g ball mill zirconium beads, 60 g PVP, and do not add isopropanol.

[0052] Step 2: ball mill the mixture at 450 rpm for 36 h (15 min pause per rotation)

[0053] Step 3, placing the ball-milled precursor in an oven at 60° C. for 12 h to thoroughly dry it;

[0054] Step 4: Place the dried precursor in a box furnace and heat it to 900°C at a heating rate of 5°C per minute for 6 hours to obtain nano-scale LATP powder.

[0055] Step 5, placing the LATP powder after high-temperature sintering in a ball mill, loading ball mill zirconium beads according to the ball-to-material mass ratio of 10:1; the ratio (mass ratio) of wet grinding solvent to LATP material is 4:1; the ball milling speed is 400rpm for ball milling; the ball milling time is 10h (15min pause for each rotation), and after ball milling, it is dried at 60°C to obtain the final LATP solid electrolyte powder.

[0056] The XRD patterns of the prepared LATP solid electrolyte powder are as follows: Figure 5 As shown in the SEM microstructure Figure 6 As shown, it can be seen that the product contains a small amount of impurities and the particle size is larger than that of the product in Example 1.

[0057] Comparative Example 2

[0058] Step 1, place 15.04 g LiOH, 56.28 g Al(NO3)3·9H2O, 300 mL tetrabutyl titanate and 172.54 g NH4H2PO4 in a 1.5 L ball mill jar, add 900 g ball mill zirconium beads and 200 mL isopropanol.

[0059] Step 2: ball mill the mixture at 450 rpm for 36 h (15 min pause per rotation)

[0060] Step 3, placing the ball-milled precursor in an oven at 60° C. for 12 h to thoroughly dry it;

[0061] Step 4, placing the dried precursor in a box furnace, heating it to 900° C. at a heating rate of 5° C. per minute for calcination, and the calcination time is 6 hours to obtain nano-scale LATP powder.

[0062] Step 5, placing the LATP powder after high-temperature sintering in a ball mill, loading ball mill zirconium beads according to the ball-to-material mass ratio of 10:1; the ratio (mass ratio) of wet grinding solvent to LATP material is 4:1; the ball milling speed is 400rpm for ball milling; the ball milling time is 10h (15min pause for each rotation), and after ball milling, it is dried at 60°C to obtain the final LATP solid electrolyte powder.

[0063] The XRD patterns of the prepared LATP solid electrolyte powder are as follows: Figure 7 As shown in the SEM microstructure Figure 8 As shown, the product contains a small amount of impurities and the powder appears to be agglomerated.

[0064] The ionic conductivity of the LATP solid electrolyte powders prepared in the examples and comparative examples is shown in Table 1.

[0065] Table 1 Ionic conductivity of LATP solid electrolyte powders prepared in Examples and Comparative Examples

[0066] sample Average particle size (μm) Ionic conductivity (mS / cm) Example 1 0.622 0.610 Example 2 0.652 0.614 Comparative Example 1 1.190 0.995 Comparative Example 2 1.728 0.155

[0067] It can be seen that the average particle size of the sample of Comparative Example 2 without PVP as a dispersant is larger, and the resulting ionic conductivity is relatively low. However, the samples prepared with PVP as a dispersant (Example 1 and Example 2) benefit from the uniform material dispersion and the dispersion effect during the high-temperature sintering process, and the resulting particle size is smaller and more uniform, and the resulting solid electrolyte ionic conductivity is higher. The sample obtained in Comparative Example 1 has a lower ionic conductivity due to the uneven ball milling in step 2, which leads to the generation of impurities during the high-temperature sintering process, and the poor LATP crystal phase, which weakens the ability to conduct lithium ions.

Claims

1. A method for preparing a low-cost LATP solid electrolyte, characterized in that: Includes steps: A lithium source, an aluminum source, a titanium source, a phosphorus source, a wet grinding solvent and PVP are mixed and ball-milled once, dried and calcined, and the calcined powder is mixed with a wet grinding solvent for a second ball-milling, and dried to obtain the LATP solid electrolyte; the lithium source, the aluminum source and the phosphorus source constitute a solid material, and the mass ratio of the PVP to the solid material is 1:3-5.

2. The method for preparing a low-cost LATP solid electrolyte according to claim 1, characterized in that: The wet grinding solvent is isopropanol and / or ethanol.

3. The method for preparing a low-cost LATP solid electrolyte according to claim 1, characterized in that: The lithium source includes one or more compounds of LiOH, Li2CO3, CH3COOLi, LiNO3, Li3PO4 and hydrates thereof; The aluminum source includes one or more compounds of Al2O3, Al(OH)3, Al2(CO3)3 and hydrates thereof; The titanium source includes one or more of (CH3CH2CHO)4Ti, (OCH2CH2CH2CH3)4Ti, TiO2, and Ti(NO3)4; The phosphorus source includes one or more of H4H2PO4, (NH4)2HPO4, and Li3PO4.

4. The method for preparing a low-cost LATP solid electrolyte according to claim 1, characterized in that: The titanium source is (OCH2CH2CH2CH3)4Ti.

5. The method for preparing a low-cost LATP solid electrolyte according to claim 1, characterized in that: The mass ratio of the wet grinding solvent to the solid material in the first ball milling is 1:1-2:1; the mass ratio of the ball to the solid material is 8-15:

1.

6. The method for preparing a low-cost LATP solid electrolyte according to claim 1, characterized in that: The rotation speed of the first ball milling is 400-500 rpm, with each rotation of 10-20 minutes and a pause of 10-20 minutes, and the total ball milling time is 36-48 hours.

7. In the secondary ball milling according to claim 1, the mass ratio of wet grinding solvent to material is 2:1-5:1; the mass ratio of ball to material is 8-15:

1.

8. The method for preparing a low-cost LATP solid electrolyte according to claim 1, characterized in that: The rotation speed of the secondary ball milling is 400-500 rpm, with each rotation of 10-20 minutes and a pause of 10-20 minutes, and the total ball milling time is 8-15 hours.

9. The method for preparing a low-cost LATP solid electrolyte according to claim 1, characterized in that: The drying temperature is 50-80°C, and the drying time is 10-12 hours.

10. The method for preparing a low-cost LATP solid electrolyte according to claim 1, characterized in that: The calcination temperature is 700-900° C., and the calcination time is 5-8 hours.

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