A method for preparing a composite solid-state electrolyte based on a ceramic particle-zeolite core-shell structure

Abstract

This invention belongs to the field of solid-state electrolyte preparation and electrochemical energy storage technology, and relates to a method for preparing a composite solid-state electrolyte based on a ceramic particle-zeolite core-shell structure. The preparation method involves uniformly dispersing ceramic particles in a zeolite-grown dispersion system, forming a good zeolite coating layer in situ on the surface of the ceramic particles, thus obtaining a ceramic particle-zeolite core-shell structure. This is then pressed into sheets and sintered to obtain a ceramic / zeolite composite structure. The ceramic / zeolite composite structure is then placed in an electrolyte or ionic liquid for negative pressure adsorption, yielding the composite solid-state electrolyte. This invention utilizes the ceramic particle-zeolite core-shell structure powder to form a dense ceramic particle / zeolite composite structure without packing pores between the zeolite and ceramic particles. This avoids the obstruction of ion transport by pores and utilizes the core-shell structure to prevent side reactions of the ceramic particles during electrochemical processes, thereby improving the ionic conductivity and stability of the composite solid-state electrolyte.

Description

Technical Field

[0001] This invention belongs to the field of solid electrolyte preparation and electrochemical energy storage technology, and relates to a method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure. Background Technology

[0002] Ceramic-based solid electrolytes (SSEs) are solid ionic conductor electrolytes used in lithium (or sodium, potassium, magnesium, aluminum, zinc, etc.) ion batteries. They can improve battery safety, solve problems such as leakage and flammability associated with organic electrolytes, and achieve higher power density and cycleability. Currently, there are many common types of ceramic-based solid electrolytes, including oxides, sulfides, and phosphates. However, the porosity inherent in the sintering process of ceramic-based solid electrolytes makes it difficult to achieve the desired ionic conductivity. Currently, special sintering techniques and powder granulation techniques can improve the conductivity of ceramic-based solid electrolytes by increasing density, but the hindering effect of pores on ion conduction cannot be eliminated. Furthermore, sulfide solid electrolytes, which have high ionic conductivity, can release toxic sulfur-containing gases during use due to side reactions, leading to battery failure and safety issues. Therefore, reducing the porosity of ceramic-based solid electrolytes is a pressing problem that needs to be solved to improve their conductivity and utilization value. Summary of the Invention

[0003] To address the problems of pores hindering ion transport in current ceramic-based solid electrolytes and the release of toxic sulfur-containing gases from side reactions in sulfide solid electrolytes, this invention provides a method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure.

[0004] Zeolite is a porous material that can sieve substances at the molecular level; its general chemical formula is A. m B p O 2p ·nH2O, structural formula A (x / q) [(AlO2) x (SiO2) y ]n(H2O). Where: A is cations such as Ca, Na, K, Ba, Sr, etc., B is Al and Si, p is the valence of the cation, m is the number of cations, n is the number of water molecules, x is the number of Al atoms, y is the number of Si atoms, and (y / x) is usually between 1 and 5. In the prior art, zeolite can be used as a solid electrolyte with good ionic conductivity [Nature, 2021, 592(7855):551-557].

[0005] This invention forms a good coating layer by in-situ growth of zeolite on the surface of ceramic particles, forming a ceramic particle-zeolite core-shell structure. The zeolite fills the pores of the ceramic-based solid electrolyte, forming a composite structure that connects ion transport.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure includes the following steps:

[0008] (1) Solid electrolyte ceramic particles are uniformly dispersed in a dispersion system for zeolite growth, so that zeolite nucleates and grows along the surface of ceramic particles. After washing and drying, ceramic particle-zeolite core-shell structure powder is obtained.

[0009] (2) Press the ceramic particle-zeolite core-shell structure powder described in step (1) into tablets to obtain an electrolyte blank; or, mix the ceramic particle-zeolite core-shell structure powder described in step (1) with the zeolite powder described in step (1) evenly, and then press into tablets to obtain an electrolyte blank.

[0010] (3) Sinter the electrolyte blank described in step (2) to prepare a ceramic / zeolite composite structure;

[0011] (4) The ceramic / zeolite composite structure described in step (3) is placed in an electrolyte or ionic liquid and adsorbed under negative pressure to obtain a composite solid electrolyte.

[0012] Preferably, the solid electrolyte ceramic particles in step (1) are selected from oxides, sulfides or phosphates prepared by solid-phase method; more preferably, the solid electrolyte ceramic particles in step (1) are sodium ion solid electrolyte ceramic particles with a particle size of 0.5 to 10 μm.

[0013] Preferably, the washing and drying in step (1) involves washing at least 3 times and drying at a temperature of 50–90°C.

[0014] Preferably, the dispersion system for zeolite growth in step (1) comprises: water as the dispersant; and the dispersed phases including water-soluble lithium, sodium, or potassium aluminates and lithium, sodium, or potassium silicates; wherein the concentrations of both aluminates and silicates in the dispersion system are 1 mol / L. -1 .

[0015] More preferably, the dispersed phase is sodium aluminate and sodium silicate in a molar ratio of 1:1.1.

[0016] More preferably, the mass-to-volume ratio of the solid electrolyte ceramic particles to the dispersion system in step (1) is 1:(2.17~6.55)g / mL.

[0017] Step (1) controls the thickness of the zeolite coating on the surface of ceramic particles by changing the growth time or the raw material ratio.

[0018] Preferably, the growth time in step (1) is 24-100h.

[0019] Preferably, in step (1), the solid electrolyte ceramic particles are uniformly dispersed in the zeolite growth dispersion system by stirring or ultrasonication. The dispersion method used is one or more of magnetic stirring, mechanical stirring or ultrasonic dispersion, so that the ceramic particles are always in a suspended state during the growth of zeolite along the surface of the ceramic particles.

[0020] Preferably, the pressure of the tablet compression in step (2) is 10-30 MPa; more preferably 20 MPa.

[0021] Preferably, the green blank in step (3) is sintered at 600-1200°C in an ion-rich environment to prepare a ceramic / zeolite composite structure; the ion-rich environment is an environment of lithium, sodium, potassium, magnesium, aluminum or zinc vapor.

[0022] More preferably, the sintering temperature in step (3) is 1000℃ to ensure the formation of a dense structure while preventing ion loss.

[0023] Preferably, the electrolyte in step (4) is selected from 1 mol L... -1 An aqueous solution of Li₂SO₄, Na₂SO₄, K₂SO₄, MgSO₄ or ZnSO₄, or 1 mol L -1 The ionic liquid is selected from any one of the ester-based electrolytes of LiPF6, NaPF6, or KPF6; -1 LiTFSI, NaTFS or KTFSI ionic liquids.

[0024] Preferably, the negative pressure adsorption time in step (4) is 8-12 hours.

[0025] Preferably, the negative pressure condition in step (4) is provided by a glove box or a vacuum drying oven to ensure that ions are fully filled into the micro-ordered pores of the zeolite.

[0026] The composite solid electrolyte based on the ceramic particle-zeolite core-shell structure was prepared by the above method.

[0027] Preferably, the mass ratio of zeolite in the ceramic particle-zeolite core-shell structured powder is 10-30 wt%.

[0028] Terminology Explanation

[0029] Ceramic particle-zeolite core-shell structured powder: Zeolite with a three-dimensional ordered microporous structure is uniformly grown on the surface of ceramic particles to form a uniform coating layer, thus obtaining ceramic particle-zeolite core-shell structured powder.

[0030] Beneficial effects of the present invention

[0031] This invention utilizes a ceramic particle-zeolite core-shell structure powder to form a dense ceramic particle / zeolite composite structure without packing pores between the zeolite and ceramic particles. This avoids the obstruction of ion transport by pores and, by utilizing the core-shell structure, prevents side reactions of ceramic particles during electrochemical processes, thereby improving the ionic conductivity and stability of inorganic solid electrolytes. This provides a theoretical basis and technical support for improving the conductivity and stability of solid electrolytes. Attached Figure Description

[0032] Figure 1 Na3Zr2Si2PO was prepared in Examples 1-3 of this invention. 12 X-ray powder diffraction pattern of ceramic particles-NaAlSiO zeolite core-shell structure powder.

[0033] Figure 2 Na3Zr2Si2PO was prepared in Example 2 of this invention. 12 Transmission electron microscope image of ceramic particles - NaAlSiO zeolite core-shell structure powder.

[0034] Figure 3 The electrochemical impedance spectroscopy is shown in Examples 1-3 of this invention before the composite solid electrolyte is used to confine ions.

[0035] Figure 4 The electrochemical impedance spectroscopy is obtained after confining ions in the composite solid electrolyte prepared in Examples 1-3 of this invention.

[0036] Figure 5 Na3Zr2Si2PO was prepared in Example 3 of this invention. 12 Cross-sectional scanning electron microscope image of ceramic particle-NaAlSiO zeolite composite sheet.

[0037] Figure 6 Na3Zr2Si2PO was prepared as Comparative Example 1 of this invention. 12 Cross-sectional scanning electron microscope image of the slice. Detailed Implementation

[0038] The present invention will be further described below with reference to specific embodiments and comparative examples and the accompanying drawings, but is not limited thereto.

[0039] The raw materials used in the examples and comparative examples are all conventional raw materials.

[0040] Example 1

[0041] A method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure includes the following steps:

[0042] (1) 1.5g of Na3Zr2Si2PO4 prepared by solid-state method 12Phosphate ceramic particles (0.5-10 μm in size) were uniformly dispersed in 0.00171 L 1 mol L solution by magnetic stirring. -1 A suspension was formed in an aqueous solution of sodium silicate, and then 0.00155 L of 1 mol L⁻¹ sodium silicate solution was slowly added. -1 Sodium aluminate was added and stirred for 2 hours. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted for 36 hours to allow zeolite to nucleate and grow along the surface of ceramic particles. After washing three times and drying at 60°C, ceramic particle-zeolite core-shell structured powder was obtained, with the zeolite mass ratio controlled at 10 wt%.

[0043] (2) The ceramic particles-zeolite core-shell structure powder from step (1) is pressed into tablets under a pressure of 20 MPa to obtain electrolyte preforms.

[0044] (3) The green blank from step (2) is subjected to Na3Zr2Si2PO4. 12 A ceramic / zeolite composite structure was prepared by sintering at 1000℃ in a sodium-rich ion environment provided by the masterbatch powder. At 25℃, the sodium ion conductivity of the ceramic / zeolite composite structure was 1.57 × 10⁻⁶. -4 S cm -1 .

[0045] (4) Place the ceramic / zeolite composite structure from step (3) in a 1 mol L -1 A composite solid electrolyte was prepared by adsorption under negative pressure in a glove box for 8 hours in a Na₂SO₄ solution. At 25°C, the sodium ion conductivity of the composite solid electrolyte was 1.59 × 10⁻⁶. -3 S cm -1 .

[0046] Example 2

[0047] A method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure includes the following steps:

[0048] (1) 1.5g of Na3Zr2Si2PO4 prepared by solid-state method 12 Phosphate ceramic particles (0.5-10 μm in diameter) were uniformly dispersed in 0.00342 L of 1 mol / L solution by magnetic stirring. -1 A suspension was formed in an aqueous solution of sodium silicate, and then 0.00311 L of 1 mol L⁻¹ was slowly added. -1 Sodium aluminate was added and stirred for another 2 hours. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted for 60 hours to allow zeolite to nucleate and grow along the surface of ceramic particles. After washing three times and drying at 60°C, ceramic particle-zeolite core-shell structured powder was obtained, with the zeolite mass ratio controlled at 20 wt%.

[0049] (2) The ceramic particles-zeolite core-shell structure powder from step (1) is pressed into tablets under a pressure of 20 MPa to obtain electrolyte preforms.

[0050] (3) The green blank from step (2) is processed by Na3Zr2Si2PO4. 12 A ceramic / zeolite composite structure was prepared by sintering the masterbatch in a sodium-rich ion environment at 1000℃. At 25℃, the sodium ion conductivity of the ceramic / zeolite composite structure was 1.73 × 10⁻⁶. -4 S cm -1 .

[0051] (4) Place the ceramic / zeolite composite structure from step (3) in a 1 mol L -1 A composite solid electrolyte was prepared by adsorption under negative pressure in a glove box for 8 hours in a Na₂SO₄ solution. At 25°C, the sodium ion conductivity of the composite solid electrolyte was 2.53 × 10⁻⁶. -3 S cm -1 .

[0052] Example 3

[0053] A method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure includes the following steps:

[0054] (1) 1.5g of Na3Zr2Si2PO4 prepared by solid-state method 12 Phosphate ceramic particles (particle size 0.5-10 μm) were uniformly dispersed in 0.00515 L 1 mol L solution by magnetic stirring. -1 A suspension was formed in an aqueous solution of sodium silicate, and then 0.00468 L of 1 mol L⁻¹ was slowly added. -1 Sodium aluminate was added and stirred for 24 hours. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted for 100 hours to allow zeolite to nucleate and grow along the surface of ceramic particles. After washing three times and drying at 60°C, ceramic particle-zeolite core-shell structured powder was obtained, with the zeolite mass ratio controlled at 30 wt%.

[0055] (2) The ceramic particles-zeolite core-shell structure powder from step (1) is pressed into tablets under a pressure of 20 MPa to obtain electrolyte preforms.

[0056] (3) The green blank from step (2) is subjected to Na3Zr2Si2PO4. 12 A ceramic / zeolite composite structure was prepared by sintering at 1000℃ in a sodium-rich ion environment provided by the masterbatch powder. At 25℃, the sodium ion conductivity of the ceramic / zeolite composite structure was 1.35 × 10⁻⁶. -4 S cm -1 .

[0057] (4) Place the ceramic / zeolite composite structure from step (1) in a 1 mol L -1 A composite solid electrolyte was prepared by adsorption under negative pressure in a glove box for 8 hours in a Na₂SO₄ solution. At 25°C, the sodium ion conductivity of the composite solid electrolyte was 2.27 × 10⁻⁶. -3 S cm -1 .

[0058] Comparative Example 1

[0059] (1) Na3Zr2Si2PO4 prepared by solid-state method 12 Phosphate ceramic particles were pressed into sheets under a pressure of 20 MPa to obtain electrolyte preforms.

[0060] (2) The raw material from step (1) was sintered at 1000°C in the ion-rich environment described in Example 2 to prepare an inorganic solid electrolyte. At 25°C, the sodium ion conductivity of the inorganic solid electrolyte was 9.7 × 10⁻⁶. -5 S cm -1 .

[0061] Figure 1 Na3Zr2Si2PO was prepared in Examples 1-3 of this invention. 12 X-ray powder diffraction pattern of ceramic particles-NaAlSiO zeolite core-shell structure powder. Figure 1 This indicates that the core-shell structure formation process involves Na3Zr2Si2PO4. 12 The ceramic particles were not destroyed, and Na3Zr2Si2PO4 was formed. 12 Ceramic particles-NaAlSiO zeolite composite phase.

[0062] Figure 2 Na3Zr2Si2PO was prepared in Example 2 of this invention. 12 Transmission electron microscope image of ceramic particles-NaAlSiO zeolite core-shell structured powder. The image shows a uniform core-shell structure.

[0063] Figure 3 The figures show the electrochemical impedance spectroscopy (EIS) spectra of the composite solid electrolytes prepared in Examples 1-3 of this invention before ion confinement. The figures demonstrate that zeolite filling of the packing pores improves the conductivity of sodium ions.

[0064] Figure 4 The figures show the electrochemical impedance spectroscopy (EIS) spectra of the composite solid electrolytes prepared in Examples 1-3 of this invention after ion confinement. The figures show that the intrinsic ion channels of zeolite ions have an effect on improving the conductivity of sodium ions.

[0065] Figure 5 Na3Zr2Si2PO was prepared in Example 3 of this invention. 12Cross-sectional scanning electron microscope image of ceramic particle-NaAlSiO zeolite composite structure sheet (magnified to 1.98kx).

[0066] Figure 6 Na3Zr2Si2PO was prepared as Comparative Example 1 of this invention. 12 Cross-sectional scanning electron microscope image of the slice (magnified to 1.98kx). (By...) Figure 6 It can be seen that there are a large number of deposited pores between the ceramic particles; Figure 5 and Figure 6 In comparison, the number of pores between ceramic particles is significantly reduced.

Claims

1. A method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure, characterized in that, Includes the following steps: (1) Solid electrolyte ceramic particles are uniformly dispersed in a dispersion system for zeolite growth, so that zeolite nucleates and grows along the surface of ceramic particles. After washing and drying, ceramic particle-zeolite core-shell structure powder is obtained. (2) Press the ceramic particle-zeolite core-shell structure powder described in step (1) into tablets to obtain an electrolyte preform; (3) Sinter the electrolyte blank described in step (2) to prepare a ceramic / zeolite composite structure; (4) The ceramic / zeolite composite structure described in step (3) is placed in an electrolyte or ionic liquid and adsorbed under negative pressure to obtain a composite solid electrolyte. The solid-state electrolyte ceramic particles are Na3Zr2Si2PO 12 Phosphate ceramic particles; In step (3), the green blank is sintered in an ion-rich environment at 600–1200 °C to prepare a ceramic / zeolite composite structure; the ion-rich environment is a sodium vapor environment. The dispersion system for zeolite growth described in step (1) is: water as the dispersant and sodium aluminate and sodium silicate in a molar ratio of 1:1.

1. The mass ratio of zeolite in the ceramic particle-zeolite core-shell structured powder is 10-30 wt%.

2. The method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure according to claim 1, characterized in that, The particle size of the solid electrolyte ceramic particles mentioned in step (1) is 0.5 to 10 μm.

3. The method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure according to claim 1, characterized in that, In step (1), the solid electrolyte ceramic particles are uniformly dispersed in 1 mol L -1 In an aqueous silicate solution, a suspension is formed, and then 1 mol L is slowly added. -1 Sodium aluminate aqueous solution; washing and drying in step (1): washing at least 3 times, and drying at 50-90 ℃.

4. The method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure according to claim 3, characterized in that, The mass-to-volume ratio of the solid electrolyte ceramic particles to the dispersion system in step (1) is 1:(2.17~6.55)g / mL.

5. The method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure according to claim 1, characterized in that, The growth time in step (1) is 24-100 hours.

6. The method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure according to claim 1, characterized in that, In step (1), the solid electrolyte ceramic particles are uniformly dispersed in the zeolite-grown dispersion system by stirring or ultrasonication. The dispersion method used is one or more of magnetic stirring, mechanical stirring or ultrasonic dispersion.

7. The method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure according to claim 1, characterized in that, The pressure of the tablets in step (2) is 10 to 30 MPa.

8. A method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure according to claim 7, characterized in that, The pressure of the tablet compression in step (2) is 20 MPa.

9. A method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure according to claim 1, characterized in that, The sintering temperature in step (3) is 1000 ℃.

10. A method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure according to claim 1, characterized in that, The electrolyte mentioned in step (4) is selected from 1 mol L -1 An aqueous solution of Li₂SO₄, Na₂SO₄, K₂SO₄, MgSO₄ or ZnSO₄, or 1 mol L -1 The electrolyte is selected from any one of the ester-based electrolytes of LiPF6, NaPF6, or KPF6; the ionic liquid is selected from 1 mol L. -1 LiTFSI, NaTFS or KTFSI ionic liquids.

11. A method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure according to claim 1, characterized in that, The negative pressure adsorption time in step (4) is 8-12 h.

12. The method for preparing a composite solid electrolyte based on a ceramic particle-zeolite core-shell structure according to claim 1, characterized in that, The negative pressure conditions described in step (4) are provided by a glove box or a vacuum drying oven.

13. A composite solid electrolyte based on a ceramic particle-zeolite core-shell structure prepared by the preparation method according to any one of claims 1-12.

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