A high-strength inorganic solid-state electrolyte film based on a NASICON phase composite and a preparation method thereof

Abstract

The application belongs to the technical field of solid electrolyte preparation and electrochemical energy storage, and relates to a high-strength inorganic solid electrolyte film based on NASICON phase composite and a preparation method thereof. The application is prepared by compounding NZSP and electrolyte materials such as LATP under 10-30 MPa to obtain electrolyte blanks, and then sintering to form lithium-sodium composite solid electrolyte films with high mechanical strength. The lithium-sodium solid electrolyte film based on NASICON phase composite provided by the application effectively improves the mechanical strength of electrolyte films such as LATP and effectively improves the lithium ion conductivity. The application provides a theoretical basis and technical support for promoting the practicality of lithium ion solid electrolytes such as LATP.

Description

Technical Field

[0001] This invention belongs to the field of solid electrolyte preparation and electrochemical energy storage technology, and relates to a high-strength inorganic solid electrolyte membrane based on NASICON phase composite and its preparation method. Background Technology

[0002] High-energy-density solid-state lithium batteries require ceramic-based solid electrolytes to achieve a balance between ionic conductivity and mechanical strength. The core requirement is high overall ionic conductivity (at least 10⁻⁶ at room temperature). -4 (S / cm scale) to ensure rapid ion transport. In terms of mechanical properties, it needs to have sufficient rigidity and a dense microstructure to physically prevent lithium dendrite penetration and ensure battery safety; it also needs to overcome its intrinsic brittleness to develop a thin-layer, large-scale preparation process to meet the comprehensive requirements of high specific energy, long life and high safety.

[0003] Li in the NASICON phase 1.3 Al 0.3 Ti 1.7 (PO4)3(LATP) is a three-dimensional framework formed by TiO6 octahedra and PO4 tetrahedra sharing vertices. Li ＋ Diffusion occurs within the interstitial channels. The room temperature ionic conductivity is approximately 10⁻⁶. -4 ~10 -3 With an activation energy of 0.3~0.4 eV and good resistance to moisture and oxidation, it is suitable for practical production environments. It has an electrochemical window of ~5 V and high hardness (~10 GPa), which can suppress lithium dendrite puncture. However, LATP electrolyte membranes prepared by conventional solid-state sintering have low strength and are easily broken during use, limiting their practical application. Furthermore, inorganic solid electrolyte membranes such as garnet-type membranes also face the problems of low strength and fragility.

[0004] Na3Zr2Si2PO, which is also a NASICON phase 12 (NZSP) is a three-dimensional framework formed by connecting ZrO6 octahedra and SiO4 / PO4 tetrahedra at common vertices, and Na + Located at interstitial sites, they form rapid migration channels. The room temperature ionic conductivity is approximately 10⁻⁶. -4 ~10 -3 S / cm, wide electrochemical window (~5 V vs. Na) ＋ / Na). Its rigid structure (high mechanical strength) can suppress dendrite growth and improve battery safety. Its electrolyte membrane has a lower sintering temperature than LATP.

[0005] Research on solid-state electrolytes typically focuses on their electrochemical performance. However, during lithium-ion battery operation, electrode expansion and contraction, as well as lithium penetration, can lead to electrolyte failure. In addition to fracture behavior (especially elastic modulus), mechanical properties and hardness also need to be considered [Ceramics International 45 (2019) 14697–14703]. Factors affecting these mechanical properties mainly include sintering temperature, stoichiometric repeatability, grain boundary blocking effect, and electrochemical uncertainties. Reducing the particle size of LATP powder can suppress microcrack formation, thereby improving its mechanical properties [Nat. Mater. 15 (2016) 1182]. Furthermore, reducing the second-phase content and increasing density are beneficial for improving mechanical properties [Ceramics International 45 (2019) 14697–14703]. Summary of the Invention

[0006] To address the problems of low mechanical strength and fragility in LATP ceramic electrolyte membranes prepared by conventional sintering methods, this invention provides a high-strength inorganic solid electrolyte membrane based on NASICON phase composite and its preparation method. This invention forms a high-mechanical-strength inorganic electrolyte membrane by compositing easily sinterable NZSP with a lithium-ion inorganic solid electrolyte.

[0007] The technical solution of the present invention is as follows: A high-strength inorganic solid electrolyte membrane based on NASICON phase composite and its preparation method, comprising the following steps: (1) Preparation of NZSP powder and LATP powder; Preferred methods: solid-phase preparation of NZSP solid electrolyte powder and LATP solid electrolyte powder; (2) The NZSP powder and LATP powder obtained in step (1) are mixed evenly to obtain the precursor; (3) Press the precursor from step (2) into tablets at 10-30 MPa to obtain an electrolyte preform; (4) The green blank from step (3) is sintered in a conventional environment at 950-1250 °C to prepare a lithium-sodium composite solid electrolyte membrane.

[0008] According to a preferred embodiment of the present invention, the powder size in step (1) is ≤10 μm to ensure uniform mixing of NZSP and LATP powder.

[0009] According to a preferred embodiment of the present invention, the mass ratio of NZSP powder to LATP powder in step (2) is x:1-x (0.01≤x≤0.4), and more preferably 0.1:0.9.

[0010] According to a preferred embodiment of the present invention, the mixing of NZSP powder and LATP powder in step (2) is ball milling or sand milling to ensure uniform mixing.

[0011] According to a preferred embodiment of the present invention, in step (3), the precursor obtained in step (2) is pressed into tablets at 15 to 20 MPa.

[0012] According to a preferred embodiment of the present invention, the sintering environment of the green blank in step (4) is a conventional environment without external atmosphere or external pressure, so as to simplify the process and reduce costs.

[0013] According to a preferred embodiment of the present invention, the sintering temperature of the green blank in step (4) is 1000-1200 °C.

[0014] According to a preferred embodiment of the present invention, the sintering time of the green blank in step (4) is 3 to 6 hours, and more preferably 4 to 5 hours.

[0015] The present invention also provides the application of the above-mentioned high-strength inorganic solid electrolyte membrane based on NASICON phase composite in solid-state lithium batteries.

[0016] Terminology Explanation High-strength inorganic solid electrolyte membrane based on NASICON phase composite: NZSP powder with high ionic conductivity and NASICON phase is physically mixed with lithium-ion inorganic solid electrolyte powder, and then pressed and sintered to form a high-strength composite solid electrolyte membrane.

[0017] Beneficial effects of the present invention This invention prepares an inorganic solid electrolyte membrane by combining NZSP and LATP, effectively improving both the mechanical strength and lithium-ion conductivity of the LATP electrolyte membrane. This provides a theoretical basis and technical support for advancing the practical application of lithium-ion solid electrolytes. Attached Figure Description

[0018] Figure 1 This is an X-ray powder diffraction pattern of the lithium-sodium composite solid electrolyte prepared in Example 1 of the present invention; Figure 2 The electrochemical impedance spectroscopy curve of the lithium-sodium composite solid electrolyte prepared in Example 1 of this invention is shown. Figure 3 This is a photograph of the encapsulated battery containing the lithium-sodium composite solid electrolyte prepared in Example 1 of the present invention. Figure 4 This is a photograph of the encapsulated battery containing the lithium-sodium composite solid electrolyte prepared in Example 2 of the present invention. Figure 5 Three-point bending strength test of the lithium-sodium composite solid electrolyte prepared in Example 2 of this invention; Figure 6This is a photograph of the encapsulated battery containing the lithium-sodium composite solid electrolyte prepared in Example 3 of the present invention. Figure 7 This is a photograph of the encapsulated battery containing the lithium-sodium composite solid electrolyte prepared in Example 3 of the present invention. Figure 8 This is a photograph of the encapsulated battery containing the lithium-sodium composite solid electrolyte prepared in Example 5 of the present invention. Figure 9 This is the X-ray powder diffraction pattern of the lithium solid electrolyte prepared in Comparative Example 1 of the present invention. Figure 10 The electrochemical impedance spectroscopy curve of the lithium solid electrolyte prepared in Comparative Example 1 of this invention is shown. Figure 11 This is a physical image of the lithium solid electrolyte encapsulated battery prepared in Comparative Example 1 of the present invention. Figure 12 The three-point bending strength test is performed on the lithium-sodium composite solid electrolyte prepared in Comparative Example 1 of this invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described in further detail below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. The raw materials used in the embodiments and comparative examples are all conventional raw materials.

[0020] Example 1 A method for preparing a high-strength inorganic solid electrolyte membrane based on NASICON phase composite includes the following steps: (1) NZSP solid electrolyte powder and LATP solid electrolyte powder were prepared, wherein the size of the electrolyte powder was ≤10μm; (2) The NZSP powder and LATP powder obtained in step (1) are ball-milled and mixed evenly at a mass ratio of 0.01:0.99 to obtain the precursor; (3) The precursor in step (2) is pressed into tablets at 20 MPa to obtain an electrolyte preform; (4) The green blank from step (3) was sintered at 1200 °C for 6 h in a conventional environment to prepare a lithium-sodium composite solid electrolyte membrane. The XRD test results are as follows: Figure 1 As shown, this indicates that the phase is LATP; according to Figure 2 The electrolyte membrane conductivity, as measured by electrochemical impedance spectroscopy, is 8.8 × 10⁻⁶. -4 S cm -1 During the encapsulation of coin cells at 1000 psi pressure, the electrolyte membrane, such as... Figure 3 whole.

[0021] Example 2 A method for preparing a high-strength inorganic solid electrolyte membrane based on NASICON phase composite includes the following steps: (1) NZSP solid electrolyte powder and LATP solid electrolyte powder were prepared, wherein the size of the electrolyte powder was ≤10μm; (2) The NZSP powder and LATP powder obtained in step (1) are ball-milled and mixed evenly at a mass ratio of 0.4:0.6 to obtain the precursor; (3) The precursor in step (2) is pressed into tablets at 15 MPa to obtain an electrolyte preform; (4) The green blank from step (3) was sintered at 1000 °C for 4 h in a conventional environment to prepare a lithium-sodium composite solid electrolyte membrane. The conductivity of the electrolyte membrane was 8.5 × 10⁻⁶. -4 S cm -1 During the encapsulation of coin cells at 1000 psi pressure, the electrolyte membrane, such as... Figure 4 Complete; the breaking pressure of the electrolyte sheet was measured to be 56.105 N / mm using a three-point bending strength test. 2 ( Figure 5 ), compared to Comparative Example 1 (13.032 N / mm) 2 It increased by 3.3 times.

[0022] Example 3 A method for designing and preparing a high-strength inorganic solid electrolyte membrane based on NASICON phase composite includes the following steps: (1) NZSP solid electrolyte powder and LATP solid electrolyte powder were prepared, wherein the size of the electrolyte powder was ≤10μm; (2) The NZSP powder and LATP powder obtained in step (1) are ball-milled and mixed evenly at a mass ratio of 0.2:0.8 to obtain the precursor; (3) The precursor in step (2) is pressed into tablets at 15 MPa to obtain an electrolyte preform; (4) The green blank from step (3) was sintered at 1100 °C for 5 h in a conventional environment to prepare a lithium-sodium composite solid electrolyte membrane. The conductivity of the electrolyte membrane was 8.7 × 10⁻⁶. -4 S cm -1 During the encapsulation of coin cells at 1000 psi pressure, the electrolyte membrane, such as... Figure 6 whole.

[0023] Example 4 A method for preparing a high-strength inorganic solid electrolyte membrane based on NASICON phase composite includes the following steps: (1) NZSP solid electrolyte powder and LATP solid electrolyte powder were prepared, wherein the size of the electrolyte powder was ≤10μm; (2) The NZSP powder and LATP powder obtained in step (1) are uniformly mixed at a mass ratio of 0.1:0.9 to obtain the precursor; (3) The precursor in step (2) is pressed into tablets at 20 MPa to obtain an electrolyte preform; (4) The green blank from step (3) was sintered at 1100 °C for 4 h in a conventional environment to prepare a lithium-sodium composite solid electrolyte membrane. The conductivity of the electrolyte membrane was 9.1 × 10⁻⁶. -4 S cm -1 During the encapsulation of coin cells at 1000 psi pressure, the electrolyte membrane, such as... Figure 7 whole.

[0024] Example 5 A method for preparing a high-strength inorganic solid electrolyte membrane based on NASICON phase composite includes the following steps: (1) NZSP solid electrolyte powder and LATP solid electrolyte powder were prepared, wherein the size of the electrolyte powder was ≤10μm; (2) The NZSP powder and LATP powder obtained in step (1) are mixed evenly by sand milling at a mass ratio of 0.3:0.7 to obtain the precursor; (3) The precursor in step (2) is pressed into tablets at 15 MPa to obtain an electrolyte preform; (4) The green blank from step (3) was sintered at 1000 °C for 5 h in a conventional environment to prepare a lithium-sodium composite solid electrolyte membrane. The conductivity of the electrolyte membrane was 8.9 × 10⁻⁶. -4 S cm -1 During the encapsulation of coin cells at 1000 psi pressure, the electrolyte membrane, such as... Figure 8 whole.

[0025] Comparative Example 1 A method for preparing an LATP inorganic solid electrolyte membrane includes the following steps: (1) Prepare LATP solid electrolyte powder, wherein the size of the electrolyte powder is ≤10 μm; (2) The powder from step (1) is pressed into tablets at 20 MPa to obtain an electrolyte preform; (3) The green blank from step (2) was sintered at 1200 °C for 6 h in a normal environment to prepare a solid electrolyte membrane. The XRD test results are as follows: Figure 9 As shown, this indicates that the phase is LATP; according to Figure 10 The electrolyte membrane conductivity, as measured by electrochemical impedance spectroscopy, is 5.6 × 10⁻⁶. -5 S cm-1 During the encapsulation of coin cells at 1000 psi pressure, the electrolyte membrane, such as... Figure 11 The electrolyte sheet fractured; the breaking pressure, measured using the three-point bending strength test, was 13.032 N / mm². 2 (like Figure 12 (As shown).

Claims

1. A method for preparing a high-strength inorganic solid electrolyte membrane based on NASICON phase composite, characterized in that, The The preparation method includes the following steps: (1) Preparation of NZSP powder and LATP powder; (2) The NZSP powder and LATP powder obtained in step (1) are mixed evenly to obtain the precursor; (3) The precursor obtained in step (2) is pressed into tablets at 10-30 MPa to obtain electrolyte preforms; (4) The green blank from step (3) is sintered in a conventional environment at 950–1250 °C to prepare a lithium-sodium composite solid-state electrolytic cell. The electrolyte membrane is a high-strength inorganic solid electrolyte membrane based on NASICON phase composite.

2. The preparation method according to claim 1, characterized in that, NZSP is prepared using a solid-state method in step (1). Solid electrolyte powder and LATP solid electrolyte powder.

3. The preparation method according to claim 1, characterized in that, The powder size in step (1) is ≤10μm.

4. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of NZSP powder to LATP powder is x:

1. x, 0.01≤x≤0.

4.

5. The preparation method according to claim 4, characterized in that, In step (2), the mass ratio of NZSP powder to LATP powder is 0.1:0.

9.

6. The preparation method according to claim 1, characterized in that, In step (2), the NZSP powder and LATP powder are mixed uniformly by ball milling or sand milling.

7. The preparation method according to claim 1, characterized in that, In step (3), the product obtained in step (2) will be... The driving body is compressed into tablets at 15–20 MPa.

8. The preparation method according to claim 1, characterized in that, In step (4), the normal environment is without external gas supply. The environment is free of external pressure; the sintering temperature of the green blank is 1000-1200 ℃.

9. The preparation method according to claim 1, characterized in that, The sintering time of the green blank in step (4) is 3 to 6 hours.

10. The preparation method according to claim 9, characterized in that, The sintering time of the green blank in step (4) is 4 to 5 hours.

11. As claimed in claim 1 The high-strength inorganic solid-state polymer based on NASICON phase composite obtained by any one of the preparation methods described in any one of the 10 claims Electrolyte membrane.

12. The high-strength inorganic solid electrolyte membrane based on NASICON phase composite as described in claim 11 in solid-state lithium batteries Applications in [the field].

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