Sulfur-doped sodium ion halide solid electrolyte material and preparation method thereof

Abstract

The invention discloses a sulfur-doped sodium ion halide solid electrolyte material and a preparation method thereof, the chemical general formula of the sulfur-doped sodium ion halide solid electrolyte material is NaxMClySz, M is any one of Al, Nb, Ta, Zr, Ga, Y and In, x is more than or equal to 1.0 and less than or equal to 3.0, y is more than or equal to 2.0 and less than or equal to 6.0, and z is more than or equal to 0.01 and less than or equal to 0.5. The heterovalent sulfur element is introduced into a NaAlCl4-based phase, a new crystal structure is induced and generated on the basis of an original phase structure, defects in a material system are increased, and the radius of S < 2-> is larger than that of Cl <->, so that the ionic conductivity (gt, 8.4 * 10 <-4 > S / cm) is improved; meanwhile, due to the introduction of the sulfur element, the interface stability of the halide electrolyte and the sodium metal negative electrode is improved; when being applied to an all-solid-state sodium metal battery, the composite material has good cycling stability.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte technology, and in particular to a sulfur-doped sodium ion halide solid electrolyte material and its preparation method. Background Technology

[0002] Sodium-ion batteries are a novel type of energy storage device that stores and releases energy by utilizing the movement of sodium ions between the positive and negative electrodes during charging and discharging. Compared to traditional lithium-ion batteries, sodium-ion batteries have advantages such as abundant resources and low cost. Furthermore, sodium-ion solid-state batteries, which use a solid electrolyte instead of the traditional liquid or gel electrolyte, further improve battery safety, energy density, and cycle life.

[0003] Currently, the main technologies for sodium-ion all-solid-state batteries include polymer solid-state electrolyte systems, oxide solid-state electrolyte systems, sulfide solid-state electrolyte systems, and halide solid-state electrolyte systems. Among them, halide solid-state electrolytes possess a higher oxidation potential than oxide solid-state electrolytes, the same deformability as sulfides, and a high oxidation potential of up to 10⁻⁶. -3 S cm -1 It possesses high ionic conductivity and shows promise for large-scale applications comparable to polymers. However, unfortunately, the reduction potential of halides is not low enough to match that of metallic sodium anodes.

[0004] Patent CN117457974A, while producing a sodium-ion halide solid electrolyte with high ionic conductivity, good electro)chemical stability, and low cost, effectively improving the electrochemical performance of solid-state sodium-ion batteries, did not improve the stability of the halide electrolyte relative to metallic Na. This resulted in the battery system being unable to be matched with a metallic sodium anode, severely hindering the application of halide all-solid-state sodium-ion batteries.

[0005] This is because halide solid electrolytes are unstable when in direct contact with sodium metal anodes. The central non-sodium metal elements are easily reduced by sodium metal to conductive byproducts, accelerating battery failure. Therefore, an intermediate layer is often needed to separate the halide solid electrolyte from the sodium metal anode. Consequently, there is an urgent need in those skilled in the art to develop a halide solid electrolyte material with high ionic conductivity and stable contact with the sodium metal anode to improve battery performance. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a sulfur-doped sodium ion halide solid electrolyte material and its preparation method.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect is to provide a sulfur-doped sodium ion halide solid electrolyte material, wherein the general chemical formula of the sulfur-doped sodium ion halide solid electrolyte material is Na. x MCl y S z Where M is any one of Al, Nb, Ta, Zr, Ga, Y and In, 1.0≤x≤3.0, 2.0≤y≤6.0, and 0.01≤z≤0.5.

[0008] Furthermore, the sulfur-doped sodium halide solid electrolyte material is used to prepare the solid electrolyte for solid sodium-ion batteries.

[0009] Furthermore, the sulfur-doped sodium ion halide solid electrolyte material is a glass-ceramic material.

[0010] The second aspect is to provide a method for preparing the above-mentioned sulfur-doped sodium ion halide solid electrolyte material, comprising the following steps: Step 1: Weigh out NaCl and MCl according to the molar ratio. （3或4或5） Na2S·9H2O is dissolved in water, and ammonium chloride is added as an auxiliary agent and stirred until well mixed. Step two, the mixture solution obtained in step one is vacuum dried, and the resulting mixture powder is annealed at 100-200℃ to obtain the sulfur-doped sodium ion halide solid electrolyte material.

[0011] Furthermore, the entire experiment was conducted under an inert atmosphere.

[0012] Furthermore, NaCl, MCl （3或4或5） The molar ratio of Na2S·9H2O is 1:(0.3-1):(0.01-0.5).

[0013] Furthermore, the vacuum drying temperature is 80-90℃.

[0014] Furthermore, the annealing process takes 3-10 hours.

[0015] The present invention adopts the above technical solution and has the following technical effects compared with the prior art: This invention introduces sulfur elements of different valences into the NaAlCl4 matrix phase, inducing a new crystal structure based on the original phase structure. This increases the number of defects in the material system. 2- Radius greater than Cl - The radius is increased, thereby improving its ionic conductivity (>8.4×10). -4 (S / cm); At the same time, the introduction of sulfur improves the interfacial stability between the halide electrolyte and the sodium metal anode; when applied to all-solid-state sodium metal batteries, it exhibits good cycle stability. Attached Figure Description

[0016] Figure 1 The X-ray diffraction (XRD) pattern of NaAlCl4 prepared for Comparative Example 1.

[0017] Figure 2 NaAlCl prepared in Example 1 3.4 S 0.3 X-ray diffraction (XRD) pattern of solid electrolyte.

[0018] Figure 3 The AC impedance spectrum of the NaAlCl4 solid electrolyte prepared for Comparative Example 1.

[0019] Figure 4 NaAlCl prepared in Example 1 3.4 S 0.3 AC impedance spectroscopy of solid electrolytes.

[0020] Figure 5 For Na / NaAlCl4 / Na(a) and Na / NaAlCl 3.4 S 0.3 SEM image of the interface after 50 cycles of / Na(b). Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the invention. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0022] Example 1 This embodiment provides a method for preparing a sulfur-doped sodium ion halide solid electrolyte material, including the following steps: Step 1: In the glove box, according to the chemical formula NaAlCl 3.4 S 0.3 Weigh out NaCl, AlCl3, and Na2S·9H2O in stoichiometric proportions and dissolve them in water. Add 2wt% ammonium chloride as an auxiliary agent and stir to mix well. Step two: The mixture solution obtained in step one is vacuum dried at 80°C, and the resulting mixture powder is annealed at 200°C for 8 hours to obtain NaAlCl. 3.4 S 0.3 Solid electrolyte. The entire experiment was conducted under an inert atmosphere to prevent the reactants from reacting with air.

[0023] Figure 2 The NaAlCl prepared in this embodiment 3.4 S 0.3The solid electrolyte X-ray diffraction (XRD) pattern shows that the structure of the product is similar to that of NaAlCl4, indicating that the doping of S ions was successful.

[0024] The solid electrolyte powder prepared by the above method was placed in a 10 mm mold, and stainless steel was used as the blocking electrode. It was pressed at 300 MPa for 5 min, and then the ionic conductivity was measured using an electrochemical workstation. The results are as follows: Figure 4 (NaAlCl prepared in this embodiment) 3.4 S 0.3 The AC impedance spectrum of the solid electrolyte yields an ionic conductivity of 8.4 × 10⁻⁶. -4 S / cm.

[0025] Example 2 This embodiment provides a method for preparing a sulfur-doped sodium ion halide solid electrolyte material, including the following steps: Step 1: In the glove box, according to the chemical formula NaNbCl... 5.6 S 0.2 Weigh out NaCl, NbCl5, and Na2S·9H2O in stoichiometric proportions and dissolve them in water. Add 1 wt% ammonium chloride as an auxiliary agent and stir to mix well. Step two: The mixture solution obtained in step one is vacuum dried at 80°C, and the resulting mixture powder is annealed at 180°C for 6 hours to obtain NaNbCl. 5.6 S 0.2 Solid electrolyte. The entire experiment was conducted under an inert atmosphere to prevent the reactants from reacting with air.

[0026] Example 3 This embodiment provides a method for preparing a sulfur-doped sodium ion halide solid electrolyte material, including the following steps: Step 1: In the glove box, according to the chemical formula Na₂ZrCl 5.7 S 0.15 Weigh out NaCl, ZrCl4, and Na2S·9H2O in stoichiometric proportions and dissolve them in water. Add 3wt% ammonium chloride as an auxiliary agent and stir to mix well. Step two: The mixture solution obtained in step one is vacuum dried at 90°C, and the resulting mixture powder is annealed at 160°C for 9 hours to obtain Na₂ZrCl. 5.7 S 0.15 Solid electrolyte. The entire experiment was conducted under an inert atmosphere to prevent the reactants from reacting with air.

[0027] Example 4 This embodiment provides a method for preparing a sulfur-doped sodium ion halide solid electrolyte material, including the following steps: Step 1: In the glove box, according to the chemical formula Na3YCl5S 0.5 Weigh out NaCl, YCl3, and Na2S·9H2O in stoichiometric proportions and dissolve them in water. Add 2wt% ammonium chloride as an auxiliary agent and stir to mix well. Step two: The mixture solution obtained in step one is vacuum dried at 90°C, and the resulting mixture powder is annealed at 190°C for 5 hours to obtain Na3YCl5S. 0.5 Solid electrolyte. The entire experiment was conducted under an inert atmosphere to prevent the reactants from reacting with air.

[0028] Example 5 This embodiment provides a method for preparing a sulfur-doped sodium ion halide solid electrolyte material, including the following steps: Step 1: In the glove box, according to the chemical formula Na3GaCl 5.4 S 0.3 Weigh out NaCl, GaCl3, and Na2S·9H2O in stoichiometric proportions and dissolve them in water. Add 1 wt% ammonium chloride as an auxiliary agent and stir to mix well. Step two: The mixture solution obtained in step one is vacuum dried at 80°C, and the resulting mixture powder is annealed at 140°C for 4 hours to obtain Na3GaCl. 5.4 S 0.3 Solid electrolyte. The entire experiment was conducted under an inert atmosphere to prevent the reactants from reacting with air.

[0029] Example 6 This embodiment provides a method for preparing a sulfur-doped sodium ion halide solid electrolyte material, including the following steps: Step 1: In the glove box, according to the chemical formula Na3InCl 5.2 S 0.4 Weigh out NaCl, InCl3, and Na2S·9H2O in stoichiometric proportions and dissolve them in water. Add 3wt% ammonium chloride as an auxiliary agent and stir to mix well. Step two: The mixture solution obtained in step one is vacuum dried at 80°C, and the resulting mixture powder is annealed at 200°C for 10 hours to obtain Na3InCl. 5.2 S 0.4 Solid electrolyte. The entire experiment was conducted under an inert atmosphere to prevent the reactants from reacting with air.

[0030] Example 7 This embodiment provides a method for preparing a sulfur-doped sodium ion halide solid electrolyte material, including the following steps: Step 1: In the glove box, according to the chemical formula NaTaCl 5.5 S 0.25 Weigh out NaCl, TaCl5, and Na2S·9H2O in stoichiometric proportions and dissolve them in water. Add 2wt% ammonium chloride as an auxiliary agent and stir to mix well. Step two: The mixture solution obtained in step one is vacuum dried at 80°C, and the resulting mixture powder is annealed at 130°C for 7 hours to obtain NaTaCl. 5.5 S 0.25 Solid electrolyte. The entire experiment was conducted under an inert atmosphere to prevent the reactants from reacting with air.

[0031] Example 8 This embodiment provides a method for preparing a sulfur-doped sodium ion halide solid electrolyte material, including the following steps: Step 1: In the glove box, according to the chemical formula NaAlCl 3.6 S 0.2 Weigh out NaCl, AlCl3, and Na2S·9H2O in stoichiometric proportions and dissolve them in water. Add 1 wt% ammonium chloride as an auxiliary agent and stir to mix well. Step two: The mixture solution obtained in step one is vacuum dried at 90°C, and the resulting mixture powder is annealed at 180°C for 10 hours to obtain NaAlCl. 3.6 S 0.2 Solid electrolyte. The entire experiment was conducted under an inert atmosphere to prevent the reactants from reacting with air.

[0032] Comparative Example 1 This embodiment provides a method for preparing a sulfur-doped sodium ion halide solid electrolyte material, including the following steps: Step 1: In the glove box, weigh out the stoichiometric amounts of NaCl and AlCl3 according to the chemical formula NaAlCl4. Step two: The mixture from step one was ball-milled in a planetary ball mill for 5 hours at a speed of 400 rpm / min. The resulting powder was then annealed at 200℃ for 8 hours to obtain the NaAlCl4 solid electrolyte. The entire experiment was conducted under an inert atmosphere to prevent the reactants from reacting with air.

[0033] Figure 1 The X-ray diffraction (XRD) pattern of the NaAlCl4 solid electrolyte prepared in this comparative example is shown. The solid electrolyte powder prepared by the above method was placed in a 10 mm mold, and stainless steel was used as the blocking electrode. It was pressed at 300 MPa for 5 min, and then the ionic conductivity was measured using an electrochemical workstation. The results are as follows: Figure 3 (The AC impedance spectrum of the NaAlCl4 solid electrolyte prepared in this comparative example) shows that the ionic conductivity is 5.3 × 10⁻⁶. -5 S / cm, lower than NaAlCl in Example 1 3.4 S 0.3 The measured ionic conductivity of the electrolyte material is 8.4 × 10⁻⁶. -4 S / cm.

[0034] Verification Example To verify that sulfur-doped sodium ion halide solid electrolyte materials can improve the stability of the electrolyte material in direct contact with the sodium metal anode, the solid electrolyte powder materials from Example 1 and Comparative Example 1 were placed in a 10mm mold and pressed at 300MPa for 5 minutes. Then, Na sheets were placed on both sides of the electrolyte and pressed at 120MPa to ensure tight adhesion between the electrolyte and the Na sheets. The electrolyte was then charged and discharged for 50 cycles in the -1V to 1V voltage range. After removal, the surface morphology of the electrolyte was observed using SEM. The results are as follows: Figure 5 As shown. It can be seen that the symmetrical battery Na / NaAlCl4 / Na (…) assembled using the electrolyte material of Comparative Example 1… Figure 5 a) After 50 cycles, impurities were generated at the interface due to a reduction reaction, which reduced the Na ion transport rate and caused unevenness at the interface, affecting interfacial contact; while the symmetric battery Na / NaAlCl assembled using the electrolyte material of Example 1... 3.4 S 0.3 / Na ( Figure 5 b) After 50 cycles, the interface was smooth and flat, with no obvious impurities generated.

[0035] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the content and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A sulfur-doped sodium ion halide solid electrolyte material, characterized in that, The general chemical formula of the sulfur-doped sodium ion halide solid electrolyte material is Na. x MCl y S z Where M is any one of Al, Nb, Ta, Zr, Ga, Y and In, 1.0≤x≤3.0, 2.0≤y≤6.0, and 0.01≤z≤0.

5.

2. The sulfur-doped sodium halide solid electrolyte material according to claim 1, characterized in that, The sulfur-doped sodium halide solid electrolyte material is used to prepare the solid electrolyte for solid sodium-ion batteries.

3. The sulfur-doped sodium halide solid electrolyte material according to claim 1, characterized in that, The sulfur-doped sodium ion halide solid electrolyte material is a glass-ceramic material.

4. A method for preparing a sulfur-doped sodium ion halide solid electrolyte material as described in any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Weigh out NaCl and MCl according to the molar ratio. （3或4或5） Na2S·9H2O is dissolved in water, and ammonium chloride is added as an auxiliary agent and stirred until well mixed. Step two, the mixture solution obtained in step one is vacuum dried, and the resulting mixture powder is annealed at 100-200℃ to obtain the sulfur-doped sodium ion halide solid electrolyte material.

5. The preparation method according to claim 4, characterized in that, The entire experiment was conducted under an inert atmosphere.

6. The preparation method according to claim 4, characterized in that, The NaCl, MCl （3或4或5） The molar ratio of Na2S·9H2O is 1:(0.3-1):(0.01-0.5).

7. The preparation method according to claim 4, characterized in that, The vacuum drying temperature is 80-90℃.

8. The preparation method according to claim 4, characterized in that, The annealing process takes 3-10 hours.

Images