Solid electrolyte LATP and preparation method thereof

Abstract

The invention relates to a solid electrolyte LATP and a preparation method thereof. The preparation method of the solid electrolyte LATP comprises the following steps: mixing solid LiOH, TiO2 and Al2O3 with an H3PO4 solution, and then carrying out a precipitation conversion reaction to obtain a Li1 + x AlxTi2-x (PO4) 3 coprecipitation precursor; cooling, washing and drying the coprecipitation precursor; and sintering the dried coprecipitation precursor in an air atmosphere to obtain the Li < 1 + x > Al < x > Ti < 2-x > (PO4) 3 solid electrolyte. The prepared solid electrolyte particles are fine and uniformly distributed, and the following defects of a traditional solid phase method that the local ratio of raw materials deviates from the stoichiometric ratio, so that the problems of poor consistency, uncontrollable particle growth, agglomeration and the like are caused, and a large amount of NH3 and CO2 gas is generated in the sintering process are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor ceramics, and in particular to a solid electrolyte LATP and a preparation method thereof. Background Art

[0002] At present, lithium-ion batteries have been widely used in new energy utilization fields such as consumer electronics, electric vehicles, and large-scale energy storage. However, the energy density of traditional lithium-ion batteries has gradually approached its theoretical limit, about 300Wh / kg. Therefore, the development of new battery technologies with both high safety and high energy density is the key to breaking through the current technical bottleneck and meeting the needs of sustainable social development. All-solid-state battery technology based on solid-state electrolytes is one of the most promising next-generation battery technologies. As the core of solid-state batteries, solid-state electrolytes have high mechanical strength, non-flammability, no leakage, and non-volatility, which provide an effective solution to fundamentally solve the safety and energy density problems of traditional liquid lithium-ion batteries. There are many types of solid electrolytes, among which the NASICON-type solid electrolyte material LATP[Li 1+x Alx Ti 2-x (PO4)3] has the best industrial prospects due to its low production cost. 1+x Al x Ti 2-x The preparation method of (PO4)3 uses nano-level titanium source solid powder and aluminum source solid powder and micron-level Li2CO3 and NH4H2PO4 for solid-phase mixing and sintering. Due to the large variety of raw materials and the large difference in particle size between various particles, it is easy to cause uneven mixing, resulting in elemental distribution segregation of the sintered LATP, generating impurities and affecting its performance. Summary of the Invention

[0003] In order to solve the above-mentioned deficiencies in the prior art, the present invention aims to provide a solid electrolyte LATP and a preparation method thereof, wherein the preparation method prepares Li 1+x Al x Ti 2-x (PO4)3 solid electrolyte has the advantages of fine particles and uniform distribution, which effectively solves the problems of poor consistency, uncontrollable particle growth and agglomeration of solid electrolytes prepared by traditional solid-phase method, as well as the generation of large amounts of NH3 and CO2 gases during the sintering process.

[0004] The purpose of the present invention is achieved through the following technical solution: A method for preparing a solid electrolyte LATP comprises the following steps:

[0005] (1) Solid LiOH, TiO2 and Al2O3 are mixed with liquid H3PO4 solution, and then a precipitation conversion reaction is carried out to obtain Li 1+x Alx Ti 2-x (PO4)3 coprecipitation precursor, 0≤x≤0.5;

[0006] (2) cooling, washing, and drying the coprecipitated precursor;

[0007] (3) Sinter the dried coprecipitated precursor in air atmosphere to obtain Li 1+x Al x Ti 2-x (PO4)3(LATP, 0≤x≤0.5) solid electrolyte.

[0008] Furthermore, in step (1), solid LiOH, TiO2 and Al2O3 are mixed with liquid H3PO4 solution to carry out precipitation conversion reaction, the reaction temperature is 150-250°C, and the reaction time is 12-24h.

[0009] Furthermore, in step (1), solid LiOH, TiO2 and Al2O3 are mixed with liquid H3PO4 solution to carry out precipitation conversion reaction, the reaction temperature is 180-220°C, and the reaction time is 18-22h.

[0010] Furthermore, in step (1), solid LiOH, TiO2 and Al2O3 are mixed with liquid H3PO4 solution to carry out precipitation conversion reaction at a reaction temperature of 200°C and a reaction time of 20 hours.

[0011] Furthermore, in step (1), according to Li 1.3 Al 0.3 Ti 1.7 The stoichiometric ratio of Li, Al, Ti and P elements in (PO4)3 is used to prepare LiOH, Al2O3, TiO2 and H3PO4 by adding them into the reactor in proportion to react. 1.3 Al 0.3 Ti 1.7 (PO4)3 co-precipitation precursor.

[0012] Furthermore, in step (2), the coprecipitated precursor is cooled to room temperature, washed with deionized water to a pH of 6.6-7.4, then washed with ethanol, and freeze-dried;

[0013] Furthermore, in step (2), the freeze-drying method includes the following steps: pre-freezing the coprecipitated precursor at a temperature of -10 to -20°C for 0.5 to 2 hours, and then treating it at a temperature of -40 to -60°C for 3 to 5 hours.

[0014] Furthermore, in step (3), the dried coprecipitated precursor is sintered at 600-750°C for 3-6 hours, and then heated to 850-1200°C and sintered for 4-9 hours. 1+x Al x Ti 2-x (PO4)3 co-precipitation precursor, the co-precipitation precursor undergoes two-stage high-temperature solid-phase sintering to obtain the final target product Li 1+x Al x Ti 2-x (PO4)3(LATP, 0≤x≤0.5) solid electrolyte, wherein the solid electrolyte particles are fine and uniformly distributed.

[0015] Furthermore, in step (3), the dried coprecipitated precursor is sintered at 700-750° C. for 5-6 hours, and then heated to 900-1100° C. and sintered for 5-8.5 hours.

[0016] Furthermore, in step (3), the dried coprecipitated precursor is sintered at 730° C. for 6 h, and then heated to 960° C. and sintered for 8 h.

[0017] The present invention also provides a solid electrolyte LATP, which is prepared by the preparation method of the solid electrolyte LATP.

[0018] The beneficial effects of the present invention are: the present invention prepares Li 1+x Al x Ti 2-x The (PO4)3 solid electrolyte features fine, uniformly distributed particles, avoiding the following shortcomings of traditional solid-phase methods: local deviations from the stoichiometric ratio of raw materials, resulting in poor consistency, uncontrollable particle growth, and agglomeration, as well as the generation of large amounts of NH3 and CO2 gases during sintering. The preparation method is stable, simple, efficient, and easy to operate and control, facilitating large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Li prepared in Example 1 1.3 Al 0.3 Ti 1.7 XRD pattern of (PO4)3.

[0020] Figure 2 Li prepared in Example 1 1.3 Al 0.3 Ti 1.7 SEM image of (PO4)3. DETAILED DESCRIPTION

[0021] In order to facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the embodiments. The contents mentioned in the embodiments are not intended to limit the present invention.

[0022] In some embodiments of the present invention, a method for preparing a solid electrolyte LATP comprises the following steps:

[0023] (1) Solid LiOH, TiO2 and Al2O3 are mixed with liquid H3PO4 aqueous solution, and then a precipitation conversion reaction is carried out to obtain Li 1+x Al x Ti 2-x (PO4)3 co-precipitation precursor, 0≤x≤0.5; the concentration of the H3PO4 aqueous solution is 75-85%.

[0024] (2) cooling, washing, and drying the coprecipitated precursor;

[0025] (3) Sinter the dried coprecipitated precursor in air atmosphere to obtain Li 1+x Al x Ti 2-x (PO4)3(LATP, 0≤x≤0.5) solid electrolyte.

[0026] In some embodiments of the present invention, in step (1), solid LiOH, TiO2 and Al2O3 are mixed with liquid H3PO4 to perform a precipitation conversion reaction at a reaction temperature of 150-250°C and a reaction time of 12-24h.

[0027] In some embodiments of the present invention, in step (1), solid LiOH, TiO2 and Al2O3 are mixed with a liquid H3PO4 aqueous solution to perform a precipitation conversion reaction at a reaction temperature of 180-220°C and a reaction time of 18-22 hours.

[0028] In some embodiments of the present invention, in step (1), according to Li 1.3 Al 0.3 Ti 1.7 The stoichiometric ratio of Li, Al, Ti and P elements in (PO4)3 is used to prepare LiOH, Al2O3, TiO2 and H3PO4 by adding them into the reactor in proportion to react. 1.3 Al 0.3 Ti 1.7 (PO4)3 co-precipitation precursor.

[0029] In some embodiments of the present invention, in step (2), the coprecipitation precursor is naturally cooled to room temperature, washed with deionized water until the pH is 6.6-7.4, and then washed 2-4 times with anhydrous ethanol, each time with a volume ratio of anhydrous ethanol to the coprecipitation precursor of 2-3:1, and then freeze-dried;

[0030] In some embodiments of the present invention, in step (2), the freeze-drying method comprises the following steps: pre-freezing the coprecipitated precursor at a temperature of -10 to -20°C for 0.5 to 2 hours, and then treating it at a temperature of -40 to -60°C for 3 to 5 hours.

[0031] In some embodiments of the present invention, in step (3), the dried coprecipitated precursor is subjected to a two-stage high-temperature solid-phase sintering, first sintered at 600-750°C for 3-6 hours, then heated to 850-1200°C and sintered for 4-9 hours.

[0032] In some embodiments of the present invention, in step (3), the dried coprecipitated precursor is subjected to a two-stage high-temperature solid-phase sintering, first sintered at 700-750°C for 5-6 hours, then heated to 900-1100°C and sintered for 5-8.5 hours.

[0033] The present invention prepares Li by coprecipitation reaction 1+x Al x Ti 2-x The (PO4)3 solid electrolyte has fine, uniformly distributed particles that accurately correspond to the diffraction peaks of the standard PDF card LiTi2(PO4)3 (PDF#35-0754). This avoids the following shortcomings of traditional solid-phase methods: local deviations from the stoichiometric ratio of the raw materials, resulting in poor consistency, uncontrollable particle growth, and agglomeration, as well as the generation of large amounts of NH3 and CO2 gases during sintering. The preparation method is stable, simple, efficient, and easy to operate and control, making it conducive to large-scale production.

[0034] Example 1

[0035] This embodiment provides a method for preparing a solid electrolyte LATP, comprising the following steps:

[0036] (1) According to Li 1.3 Al 0.3 Ti 1.7 The stoichiometric ratio of Li, Al, Ti and P elements in (PO4)3 was calculated. Solid LiOH, Al2O3, TiO2 and liquid H3PO4 solution were added into the reactor in proportion and sealed for precipitation conversion reaction. The reaction temperature was 200℃ and the reaction time was 20h to obtain Li 1.3 Al 0.3 Ti1.7 (PO4)3 co-precipitation precursor; the H3PO4 solution is an H3PO4 aqueous solution with a mass fraction concentration of 75%;

[0037] (2) The coprecipitated precursor was naturally cooled to room temperature, washed with deionized water until the pH was 7.0, and then washed twice with anhydrous ethanol, with the volume ratio of anhydrous ethanol to coprecipitated precursor being 2.5:1 each time, and then freeze-dried;

[0038] (3) In air atmosphere, the dried coprecipitated precursor was sintered at 730 °C for 6 h, and then heated to 960 °C for 8 h to obtain Li 1.3 Al 0.3 Ti 1.7 (PO4)3 solid electrolyte.

[0039] Furthermore, in step (2), the freeze-drying method includes the following steps: pre-freezing the co-precipitated precursor at -15°C for 1 hour, and then treating it at -50°C for 4 hours.

[0040] In this example, Li was synthesized by coprecipitation method. 1.3 Al 0.3 Ti 1.7 (PO4)3 solid electrolyte material, through XRD pattern comparison study, and the standard PDF card LiTi2(PO4)3 (PDF#35-0754) diffraction peak corresponds accurately, the total ionic conductivity is 8.5×10 -4 S cm -1 , the grain boundary conductivity reaches 5.2×10 -4 S cm -1 .

[0041] Example 2

[0042] This embodiment provides a method for preparing a solid electrolyte LATP, comprising the following steps:

[0043] (1) According to Li 1.3 Al 0.3 Ti 1.7 The stoichiometric ratio of Li, Al, Ti and P elements in (PO4)3 was calculated. Solid LiOH, Al2O3, TiO2 and liquid H3PO4 solution were added into the reactor in proportion and sealed for precipitation conversion reaction. The reaction temperature was 180℃ and the reaction time was 22h to obtain Li 1.3 Al 0.3 Ti 1.7 (PO4)3 co-precipitation precursor; the H3PO4 solution is an H3PO4 aqueous solution with a mass fraction concentration of 75%;

[0044] (2) The coprecipitated precursor was naturally cooled to room temperature, washed with deionized water until neutral, and then washed twice with anhydrous ethanol, with the volume ratio of anhydrous ethanol to coprecipitated precursor being 2.5:1 each time, and then freeze-dried;

[0045] (3) The dried coprecipitated precursor was sintered at 700 °C for 5 h in air atmosphere, and then heated to 900 °C for 8.5 h to obtain Li 1.3 Al 0.3 Ti 1.7 (PO4)3 solid electrolyte.

[0046] The rest of the contents of this embodiment are the same as those of Embodiment 1 and will not be repeated here.

[0047] Example 3

[0048] This embodiment provides a method for preparing a solid electrolyte LATP, comprising the following steps:

[0049] (1) According to Li 1.3 Al 0.3 Ti 1.7 The stoichiometric ratio of Li, Al, Ti and P elements in (PO4)3 was calculated. Solid LiOH, Al2O3, TiO2 and liquid H3PO4 solution were added into the reactor in proportion and sealed for precipitation conversion reaction. The reaction temperature was 220℃ and the reaction time was 18h to obtain Li 1.3 Al 0.3 Ti 1.7 (PO4)3 co-precipitation precursor; the H3PO4 solution is an H3PO4 aqueous solution with a mass fraction concentration of 75%;

[0050] (2) The coprecipitated precursor was naturally cooled to room temperature, washed with deionized water until neutral, and then washed twice with anhydrous ethanol, with the volume ratio of anhydrous ethanol to coprecipitated precursor being 2.5:1 each time, and then freeze-dried;

[0051] (3) In air atmosphere, the dried coprecipitated precursor was sintered at 750 °C for 6 h, and then heated to 1000 °C for 8 h to obtain Li 1.3 Al 0.3 Ti 1.7 (PO4)3 solid electrolyte.

[0052] The rest of the contents of this embodiment are the same as those of Embodiment 1 and will not be repeated here.

[0053] The above specific embodiments are further explanations of the technical solutions and beneficial effects of the present invention, and are not intended to limit the implementation methods. For those skilled in the art, any obvious substitutions that do not depart from the concept of the present invention are within the scope of protection of the present invention.

Claims

1. A method for preparing a solid electrolyte LATP, characterized in that: The steps include: (1) LiOH, TiO2 and Al2O3 are mixed with H3PO4 solution, and then a precipitation conversion reaction is carried out to obtain Li 1+x Al x Ti 2-x (PO4)3 coprecipitation precursor, 0≤x≤0.5; (2) cooling, washing, and drying the coprecipitated precursor; (3) Sinter the dried coprecipitated precursor in air atmosphere to obtain Li 1+x Al x Ti 2-x (PO4)3 solid electrolyte.

2. The solid electrolyte LATP according to claim 1, characterized in that: In step (1), solid LiOH, TiO2 and Al2O3 are mixed with H3PO4 solution to carry out precipitation conversion reaction at a reaction temperature of 150-250°C and a reaction time of 12-24h.

3. The solid electrolyte LATP according to claim 1, characterized in that: In step (1), solid LiOH, TiO2 and Al2O3 are mixed with H3PO4 solution to carry out precipitation conversion reaction at a reaction temperature of 180-220°C and a reaction time of 18-22h.

4. The solid electrolyte LATP according to claim 1, characterized in that: In step (1), solid LiOH, TiO2 and Al2O3 are mixed with H3PO4 solution to carry out precipitation conversion reaction at a reaction temperature of 200°C and a reaction time of 20 hours.

5. The solid electrolyte LATP according to claim 1, characterized in that: In step (1), according to Li 1.3 Al 0.3 Ti 1.7 The stoichiometric ratio of Li, Al, Ti and P elements in (PO4)3 is used to prepare LiOH, Al2O3, TiO2 and H3PO4 by adding them into the reactor in proportion to react. 1.3 Al 0.3 Ti 1.7 (PO4)3 co-precipitation precursor.

6. The solid electrolyte LATP according to claim 1, characterized in that: In step (2), the coprecipitated precursor is cooled to room temperature, washed with deionized water to a pH of 6.6-7.4, then washed with ethanol, and freeze-dried.

7. The solid electrolyte LATP according to claim 1, characterized in that: In step (3), the dried coprecipitated precursor is sintered at 600-750° C. for 3-6 hours, and then heated to 850-1200° C. and sintered for 4-9 hours.

8. The solid electrolyte LATP according to claim 1, characterized in that: In step (3), the dried coprecipitated precursor is sintered at 700-750° C. for 5-6 hours, and then heated to 900-1100° C. and sintered for 5-8.5 hours.

9. The solid electrolyte LATP according to claim 1, characterized in that: In step (3), the dried coprecipitated precursor is sintered at 730° C. for 6 h, then heated to 960° C. and sintered for 8 h.

10. A solid electrolyte LATP, characterized in that: The solid electrolyte LATP is prepared by the preparation method of any one of claims 1 to 9.

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