A lithium titanium aluminum phosphate solid electrolyte, its preparation method and application

Abstract

This invention provides a lithium titanium aluminum phosphate solid electrolyte, its preparation method, and its application. The preparation method includes the following steps: (1) mixing a lithium source, a titanium source, an aluminum source, and a solvent, adding hydrogen peroxide to obtain solution A, mixing a phosphorus source and a solvent, adding ammonia to adjust the pH to obtain solution B; (2) mixing solution A and solution B obtained in step (1), aging to obtain a lithium titanium aluminum phosphate precursor; (3) sintering the lithium titanium aluminum phosphate precursor obtained in step (2) to obtain the lithium titanium aluminum phosphate solid electrolyte. The preparation process of the lithium titanium aluminum phosphate solid electrolyte of this invention uses inexpensive and readily available inorganic salts as raw materials, has no special requirements for reaction equipment, is easy to industrialize, and produces lithium titanium aluminum phosphate solid electrolyte materials of high quality.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, and relates to a lithium titanium aluminum phosphate solid electrolyte, its preparation method and application. Background Technology

[0002] With the development of technology and the advent of the dual-carbon era, lithium-ion batteries have been widely used in electric vehicles, 3C electronics, energy storage, and other fields. However, the frequent lithium-ion battery fires in recent years have made people increasingly concerned about the safety of lithium-ion batteries. Currently, lithium-ion batteries mainly use liquid organic electrolytes, and the flammability of organic liquids and the overall thermal runaway of the battery are important factors causing battery safety problems.

[0003] Compared to traditional liquid electrolytes, solid-state electrolytes offer advantages such as low flammability, high thermal stability, no leakage, and low explosion hazard, significantly improving the safety performance of lithium-ion batteries while simultaneously increasing battery energy and reducing costs. NASICON-type lithium-ion conductors Li... 1+x Al x Ti 2-x (PO4)3(LATP) is considered one of the solid electrolyte materials suitable for commercial production due to its good stability.

[0004] CN111180703A describes a process where tetrabutyl titanate, aluminum nitrate nonahydrate, ammonium dihydrogen phosphate, and lithium acetate dihydrate are dissolved in anhydrous ethanol. The solution is stirred until all the anhydrous ethanol evaporates, resulting in a dry powder. The dried powder is then heated to obtain LATP powder.

[0005] CN111233458A discloses a lithium titanium aluminum phosphate solid electrolyte material and its preparation method. The preparation method specifically includes: (1) mixing soluble aluminum salt and precipitant in water at a molar ratio of 1:1.5-2 to obtain a mixed solution; then placing the mixed solution in a reaction vessel and heating it, filtering, washing, and drying the product to obtain an AlOOH precursor; (2) mixing the AlOOH precursor obtained in step (1) with lithium salt, titanium salt and phosphate salt in a molar ratio of Li, Al, Ti and P of (1+x):x:(2-x):3, where x = 0.3-0.5, then adding ethanol medium and ball milling, and then pre-firing and secondary molding sintering in a dry air atmosphere to obtain the lithium titanium aluminum phosphate solid electrolyte material.

[0006] The above-mentioned methods for preparing lithium titanium aluminum phosphate have problems such as poor material quality, high cost, or long preparation cycle. Therefore, it is necessary to develop a low-cost, simple, and high-quality method for preparing lithium titanium aluminum phosphate. Summary of the Invention

[0007] The purpose of this invention is to provide a lithium titanium aluminum phosphate solid electrolyte, its preparation method and application. The preparation process of the lithium titanium aluminum phosphate solid electrolyte of this invention uses inexpensive and readily available inorganic salts as raw materials, has no special requirements for reaction equipment, is easy to industrialize, and produces lithium titanium aluminum phosphate solid electrolyte materials of high quality.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a lithium aluminum titanium phosphate solid electrolyte, the method comprising the following steps:

[0010] (1) Mix lithium source, titanium source, aluminum source with solvent, add hydrogen peroxide to obtain solution A, mix phosphorus source with solvent, add ammonia to adjust pH to obtain solution B;

[0011] (2) Mix solution A and solution B obtained in step (1), and age them to obtain lithium titanium aluminum phosphate precursor;

[0012] (3) The lithium titanium aluminum phosphate precursor obtained in step (2) is sintered to obtain the lithium titanium aluminum phosphate solid electrolyte.

[0013] In the preparation method of lithium titanium aluminum phosphate described in this invention, adding H2O2 to solution A can cause Ti... 4+ Peroxytitanic acid is formed. The pH of solution B can be adjusted by adding ammonia water, and the pH can be controlled within a certain range. This avoids the problem of uneven element mixing that exists in the traditional solid-phase method for preparing LATP. At the same time, it avoids the disadvantages of the sol-gel method, such as the use of organic solvents, long preparation cycle, or the need to add expensive organometallic salts, which are costly and difficult to achieve industrial production. The preparation cost is low and the product quality is high, making it easy to achieve industrialization.

[0014] Preferably, the lithium source in step (1) includes any one or a combination of at least two of lithium carbonate, lithium nitrate, or lithium sulfate.

[0015] Preferably, the titanium source includes titanium sulfate and / or titanium oxysulfate.

[0016] Preferably, the aluminum source includes aluminum sulfate and / or aluminum nitrate.

[0017] Preferably, the solvent includes deionized water.

[0018] Preferably, the phosphorus source includes any one or a combination of at least two of phosphoric acid, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate.

[0019] Preferably, the mass concentration of hydrogen peroxide in step (1) is 20-30%, for example: 20%, 22%, 25%, 28% or 30%, etc.

[0020] Preferably, the pH adjustment in step (1) is 9 to 12, for example: 9, 9.5, 10, 11 or 12.

[0021] Preferably, the mixing method in step (2) includes heating solution A and then pumping solution B into solution A.

[0022] Preferably, the temperature for heating is 60-80°C, for example: 60°C, 65°C, 70°C, 75°C or 80°C.

[0023] Preferably, the pumping time is 1 to 10 hours, for example: 1 hour, 3 hours, 5 hours, 8 hours, or 10 hours.

[0024] Preferably, the aging time in step (2) is 1 to 4 hours, for example: 1 hour, 2 hours, 3 hours or 4 hours.

[0025] Preferably, the aged solution is filtered, washed, and dried.

[0026] Preferably, the sintering temperature in step (3) is 600 to 1000°C, for example: 600°C, 700°C, 800°C, 900°C or 1000°C.

[0027] Preferably, the sintering treatment time is 6 to 12 hours, for example: 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours or 12 hours.

[0028] In a second aspect, the present invention provides a lithium titanium aluminum phosphate solid electrolyte, which is prepared by the method described in the first aspect.

[0029] Preferably, the chemical formula of the lithium titanium aluminum phosphate solid electrolyte is Li 1+x Al x Ti 2-x (PO4)3, x is 0.3 to 0.5, for example: 0.3, 0.35, 0.4, 0.5 or 0.5, etc.

[0030] Preferably, the lithium titanium aluminum phosphate solid electrolyte is in powder form.

[0031] Thirdly, the present invention provides a lithium-ion battery comprising a lithium aluminum titanium phosphate solid electrolyte as described in the second aspect.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) In the preparation method of lithium titanium aluminum phosphate described in this invention, adding H2O2 to solution A can make Ti 4+Peroxytitanic acid is formed. The pH of solution B can be adjusted by adding ammonia water, and the pH can be controlled within a certain range. This avoids the problem of uneven element mixing that exists in the traditional solid-phase method for preparing LATP. At the same time, it avoids the disadvantages of the sol-gel method, such as the use of organic solvents, long preparation cycle, or the need to add expensive organometallic salts, which are costly and difficult to achieve industrial production. The preparation cost is low and the product quality is high, making it easy to achieve industrialization.

[0034] (2) The conductivity of the lithium aluminum titanium phosphate solid electrolyte described in this invention can reach 2.54 × 10⁻⁶. -4 above. Attached Figure Description

[0035] Figure 1 This is the XRD pattern of the lithium aluminum titanium phosphate solid electrolyte described in Example 1 of the present invention. Detailed Implementation

[0036] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0037] Example 1

[0038] This embodiment provides a lithium titanium aluminum phosphate solid electrolyte, the preparation method of which includes the following steps:

[0039] (1) Weigh 0.37 kg of lithium carbonate, 0.7 kg of aluminum sulfate octadecade, 2.33 kg of titanium oxysulfate, and 1.44 L of phosphoric acid (85%). Dissolve titanium oxysulfate in 70 L of pure water, then add aluminum sulfate octadecade and lithium carbonate in sequence, stir to dissolve, and then add 49 L of H2O2 (23%) to obtain solution A. Dissolve phosphoric acid in 70 L of pure water and adjust the pH to 11.0 with NH3·H2O to obtain solution B.

[0040] (2) Add solution A to the reaction vessel as the base liquid, heat to 70°C, pump in solution B for 2 hours, age for 4 hours, filter, wash and dry the mixed solution after reaction to obtain LATP precursor powder.

[0041] (3) The above LATP precursor powder was heated at 700℃ for 8 hours to obtain the chemical formula Li 1.3 Al 0.3 Ti 1.7 (PO4)3 powder.

[0042] The XRD pattern of the prepared lithium titanium aluminum phosphate solid electrolyte is shown in the figure. Figure 1 As shown.

[0043] Example 2

[0044] This embodiment provides a lithium titanium aluminum phosphate solid electrolyte, the preparation method of which includes the following steps:

[0045] (1) Weigh 0.64 kg of lithium sulfate monohydrate, 0.7 kg of aluminum sulfate octadecahydrate, 2.33 kg of titanium oxysulfate, and 2.415 kg of ammonium dihydrogen phosphate. Dissolve titanium oxysulfate in 70 L of pure water, then add aluminum sulfate octadecahydrate and lithium carbonate in sequence, stir to dissolve, and then add 49 L of H2O2 (23%) to obtain solution A. Dissolve ammonium dihydrogen phosphate in 70 L of pure water and adjust the pH to 9.5 with NH3·H2O to obtain solution B.

[0046] (2) Add solution A as the base liquid to the reaction vessel, heat to 70°C, pump in solution B for 8 hours, age for 4 hours, filter, wash and dry the mixed solution after reaction to obtain LATP precursor powder.

[0047] (3) The above LATP precursor powder was heated at 650℃ for 12 h to obtain the chemical formula Li 1.3 Al 0.3 Ti 1.7 (PO4)3 powder.

[0048] Example 3

[0049] This embodiment provides a lithium titanium aluminum phosphate solid electrolyte, the preparation method of which includes the following steps:

[0050] (1) Weigh 0.35 kg of lithium nitrate, 0.78 kg of aluminum nitrate nonahydrate, 2.86 kg of titanium sulfate, and 1.44 L of phosphoric acid (85%). Dissolve the titanium sulfate in 70 L of pure water, then add aluminum sulfate octadecahydrate and lithium carbonate in sequence, stir to dissolve, and then add 20 L of H2O2 (23%) to obtain solution A. Dissolve the phosphoric acid in 70 L of pure water and adjust the pH to 9.3 with NH3·H2O to obtain solution B.

[0051] (2) Add solution A as the base liquid to the reaction vessel, heat to 70°C, pump in solution B for 8 hours, age for 4 hours, filter, wash and dry the mixed solution after reaction to obtain LATP precursor powder.

[0052] (3) The above LATP precursor powder was heated at 750℃ for 8 hours to obtain the chemical formula Li 1.3 Al 0.3 Ti 1.7 (PO4)3 powder.

[0053] Example 4

[0054] The only difference between this embodiment and Embodiment 1 is that the concentration of hydrogen peroxide in step (1) is 15%, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0055] Example 5

[0056] The only difference between this embodiment and Embodiment 1 is that the concentration of hydrogen peroxide in step (1) is 35%, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0057] Example 6

[0058] The only difference between this embodiment and embodiment 1 is that step (2) does not involve heating solution A; all other conditions and parameters are exactly the same as in embodiment 1.

[0059] Comparative Example 1

[0060] Weigh out 1.59g of lithium carbonate, 3.0g of aluminum sulfate octadechydrate, 4.07g of titanium dioxide, and 10.35g of ammonium dihydrogen phosphate. Mix them thoroughly in a mortar and pestle. Incubate the mixture at 750℃ for 12 hours to obtain the chemical formula Li. 1.3 Al 0.3 Ti 1.7 (PO4)3 powder.

[0061] Comparative Example 2

[0062] 15g of lithium acetate dihydrate, 11g of aluminum nitrate nonahydrate, 57g of tetrabutyl titanate, and 34g of ammonium dihydrogen phosphate were dissolved in 2000mL of anhydrous ethanol, and the mixture was magnetically stirred until all the anhydrous ethanol evaporated. The dried powder was then collected in an alumina crucible, which was placed in a muffle furnace and heated at 450℃ for 2 hours to ensure complete reaction of the precursors. The temperature was then increased to 800℃ and held for 2 hours to obtain LATP powder.

[0063] Performance testing:

[0064] The prepared LATP powder was compressed into tablets under a pressure of 200 MPa using a powder tablet press. The tablets were then heated to 950°C in a muffle furnace and held at that temperature for 8 hours before being cooled in the furnace to obtain LATP solid electrolyte tablets.

[0065] After sanding both sides of the LATP solid electrolyte sheet, conductive silver paste was applied to both sides. After drying, electrochemical impedance spectroscopy (EIS) was performed using an electrochemical testing instrument.

[0066] The test results are shown in Table 1:

[0067] Table 1

[0068]

[0069]

[0070] As shown in Table 1, and based on Examples 1-6, the conductivity of the lithium aluminum titanium phosphate solid electrolyte of this invention can reach 2.54 × 10⁻⁶. -4 S / cm or higher.

[0071] A comparison of Examples 1 and 4-5 shows that the concentration of hydrogen peroxide used in the preparation process of the lithium titanium aluminum phosphate solid electrolyte of the present invention affects the performance of the prepared lithium titanium aluminum phosphate solid electrolyte. Controlling the hydrogen peroxide concentration at 20-30% yields better results in preparing the lithium titanium aluminum phosphate solid electrolyte. If the concentration of hydrogen peroxide is too low, impurities will appear in the product, reducing its ionic conductivity. If the concentration of hydrogen peroxide is too high, it will not have a positive effect on the ionic conductivity of the solid electrolyte, resulting in waste of raw materials.

[0072] Comparing Examples 1 and 6, it can be seen that in the preparation process of the lithium aluminum titanium phosphate solid electrolyte of the present invention, the preheating treatment of solution A in step (2) can make the obtained solid electrolyte have higher ionic conductivity.

[0073] As can be seen from the comparison between Example 1 and Comparative Examples 1 and 2, the preparation method of lithium titanium aluminum phosphate solid electrolyte of the present invention avoids the problem of uneven element mixing in the traditional solid-phase method for preparing LATP. At the same time, it avoids the disadvantages of using organic solvents, long preparation cycle or needing to add expensive organometallic salts in the sol-gel method, which are expensive and difficult to achieve industrial production. The preparation cost is low and the product quality is high, making it easy to achieve industrialization.

[0074] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a lithium aluminum titanium phosphate solid electrolyte, characterized in that, The preparation method includes the following steps: (1) Mix lithium source, titanium source, aluminum source with solvent, add hydrogen peroxide to obtain solution A, mix phosphorus source with solvent, add ammonia to adjust pH to obtain solution B; (2) Mix solution A and solution B obtained in step (1), and age them to obtain lithium titanium aluminum phosphate precursor; (3) The lithium titanium aluminum phosphate precursor obtained in step (2) is sintered to obtain the lithium titanium aluminum phosphate solid electrolyte. The pH is adjusted to 9-12 as described in step (1); The mixing method in step (2) includes heating solution A and then pumping solution B into solution A; the heating temperature is 60-80℃.

2. The preparation method according to claim 1, characterized in that, The lithium source in step (1) includes any one or a combination of at least two of lithium carbonate, lithium nitrate, or lithium sulfate.

3. The preparation method according to claim 1, characterized in that, The titanium source includes titanium sulfate and / or titanium oxysulfate.

4. The preparation method according to claim 1, characterized in that, The aluminum source includes aluminum sulfate and / or aluminum nitrate.

5. The preparation method according to claim 1, characterized in that, The solvent includes deionized water.

6. The preparation method according to claim 1, characterized in that, The phosphorus source includes any one or a combination of at least two of phosphoric acid, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate.

7. The preparation method according to claim 1 or 2, characterized in that, The mass concentration of hydrogen peroxide in step (1) is 20-30%.

8. The preparation method according to claim 1, characterized in that, The pumping time is 1 to 10 hours.

9. The preparation method according to claim 1, characterized in that, The aging time in step (2) is 1 to 4 hours.

10. The preparation method according to claim 1, characterized in that, After aging, the mixed solution is filtered, washed, and dried.

11. The preparation method according to claim 1, characterized in that, The sintering temperature in step (3) is 600–1000 °C.

12. The preparation method according to claim 1, characterized in that, The sintering process takes 6 to 12 hours.

13. A lithium aluminum titanium phosphate solid electrolyte, characterized in that, The lithium titanium aluminum phosphate solid electrolyte is prepared by the method described in any one of claims 1-12.

14. The lithium aluminum titanium phosphate solid electrolyte as described in claim 13, characterized in that, The chemical formula of the lithium aluminum titanium phosphate solid electrolyte is Li 1+x Al x Ti 2-x (PO4)3, x is 0.3 to 0.

5.

15. The lithium aluminum titanium phosphate solid electrolyte as described in claim 13, characterized in that, The lithium titanium aluminum phosphate solid electrolyte is in powder form.

16. A lithium-ion battery, characterized in that, The lithium-ion battery comprises a lithium aluminum titanium phosphate solid electrolyte as described in any one of claims 13-15.

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