A method for preparing an inorganic solid-state electrolyte

Abstract

The application provides a preparation method of inorganic solid electrolyte and belongs to the technical field of lithium ion batteries. The chemical general formula of the obtained halide inorganic solid electrolyte is Li a Al x A 1‑x Cl a+3 , wherein 1<=a<=6; 0<=x<=1; A is selected from one or more of Y 3+ , In 3+ . The application adopts a water solvent freeze-drying method, reduces the preparation cost and time of the solid electrolyte, and can realize mass production compared with a conventional ball milling method. Meanwhile, element doping can be carried out in the process, and the ionic conductivity of the prepared electrolyte material can reach 5.03*10 ‑4 S / cm, and the electrolyte material can be used in a full solid-state lithium ion battery.

Description

Technical Field

[0001] This invention relates to a method for preparing an inorganic solid electrolyte, belonging to the field of lithium-ion battery technology. Background Technology

[0002] New energy technologies have become an increasingly important part of the energy sector, with lithium batteries accounting for a growing proportion year by year. However, most traditional lithium batteries use liquid electrolytes, which can lead to a series of safety issues, such as combustion, as lithium dendrites grow during use. Using solid electrolytes instead of liquid electrolytes can effectively reduce battery safety issues, and therefore has attracted significant attention.

[0003] Currently used solid electrolytes mainly include inorganic solid electrolytes and organic solid electrolytes. Among inorganic solid electrolytes, oxides exhibit certain chemical stability, but their interfacial contact is poor and they require high-temperature calcination, making practical applications difficult. Sulfides have high ionic conductivity and better processability than oxides, but their narrow electrochemical window prevents direct matching with cathode materials, often requiring modifications for application. Organic solid electrolytes, such as PEO, have good processability and a wide electrochemical window, but their relatively low ionic conductivity is a problem that urgently needs to be solved.

[0004] Halide solid electrolytes have attracted attention and show promising application prospects due to their high lithium-ion conductivity, wide electrochemical window, good processability, and stability with cathode materials. However, the dominance of rare earth elements and the time-consuming preparation process significantly increase the actual cost of using halide solid electrolytes, thus affecting their application. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a method for preparing inorganic solid electrolytes.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for preparing an inorganic solid electrolyte includes the following steps:

[0008] S1, Under air conditions, the reaction raw materials LiCl, AlCl3, and ACl3 are added to water respectively, and stirred to dissolve and form a transparent mixed solution; wherein, the A in ACl3 is selected from Y. 3+ In 3+ One or more of the following; the molar ratio of the reaction raw materials is LiCl:AlCl3:ACl3=a:x:(1-x), 1≤a≤6; 0≤x≤1;

[0009] S2, under air conditions, the mixed solution is treated by freeze-drying to obtain Li.a Al x A 1-x Cl a+3 Precursor powder;

[0010] S3, under inert gas protection, the precursor powder is calcined to obtain calcined Li. a Al x A 1-x Cl a+x Solid electrolyte;

[0011] S4, under inert gas protection conditions, calcined Li a Al x A 1-x Cl a+x Solid electrolytes were ball-milled to obtain Li a Al x A 1-x Cl a+x Solid electrolyte powder.

[0012] Optionally, the concentration of the reactant raw materials in the mixed solution is 0.05-0.2 g / mL.

[0013] Optionally, in step S1, the stirring and dissolving is carried out using magnetic stirring at a speed of 100-500 rpm for a time of 10-60 min.

[0014] Optionally, in step S2, the freeze-drying temperature is -50 to 0°C, the vacuum degree is 0.1-20 Pa, and the freeze-drying time is 2 to 24 hours.

[0015] Optionally, the freeze-drying time is 8 to 15 hours.

[0016] Optionally, in step S3, the calcination temperature is 200-550℃, and the holding time is 2-12 hours.

[0017] Optionally, the heating rate during calcination is 3-10℃ / min.

[0018] Optionally, in step S4, the ball milling speed is 400-800 rpm and the ball milling time is 0.5-4 hours.

[0019] Optionally, the grinding balls used in the ball mill have a radius of 5-10 mm and a ball-to-material ratio of 20-40:1.

[0020] Optionally, the Li a Al x A 1-x Cl a+x Solid electrolyte powder is a crystalline phase.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention successfully synthesizes halide inorganic solid electrolytes via freeze-drying in an aqueous solvent. Compared to the traditional ball milling method, this synthesis method offers shorter synthesis time and allows for large-scale production. Furthermore, incorporating Al into the halide inorganic solid electrolyte reduces the proportion of rare earth elements, lowering preparation costs, and achieving an ionic conductivity of 5.03 × 10⁻⁶. -4 The S / cm level meets the requirements for solid electrolyte applications. Attached Figure Description

[0023] Figure 1 The X-ray diffraction pattern of the Li3InCl6 inorganic solid electrolyte powder prepared in Example 1;

[0024] Figure 2 The electrochemical impedance spectroscopy of the Li3InCl6 inorganic solid electrolyte powder prepared in Example 1 is shown.

[0025] Figure 3 The Li3Al prepared in Example 2 0.05 In 0.95 X-ray diffraction pattern of Cl6 inorganic solid electrolyte powder;

[0026] Figure 4 The Li3Al prepared in Example 2 0.05 In 0.95 Electrochemical impedance spectroscopy of Cl6 inorganic solid electrolyte powder;

[0027] Figure 5 The Li3Al prepared in Example 3 0.1 In 0.9 X-ray diffraction pattern of Cl6 inorganic solid electrolyte powder;

[0028] Figure 6 The Li3Al prepared in Example 3 0.1 In 0.9 Electrochemical impedance spectroscopy of Cl6 inorganic solid electrolyte powder;

[0029] Figure 7 The Li3Al prepared in Example 4 0.2 In 0.8 X-ray diffraction pattern of Cl6 inorganic solid electrolyte powder;

[0030] Figure 8 The Li3Al prepared in Example 4 0.2 In 0.8 Electrochemical impedance spectroscopy of Cl6 inorganic solid electrolyte powder;

[0031] Figure 9 The Li3Al prepared in Example 5 0.3 In 0.7 X-ray diffraction pattern of Cl6 inorganic solid electrolyte powder;

[0032] Figure 10 The Li3Al prepared in Example 5 0.3 In 0.7 Electrochemical impedance spectroscopy of Cl6 inorganic solid electrolyte powder;

[0033] Figure 11 The Li3Al prepared in Example 6 0.5 In 0.5 X-ray diffraction pattern of Cl6 inorganic solid electrolyte powder;

[0034] Figure 12 The Li3Al prepared in Example 6 0.5 In 0.5 Electrochemical impedance spectroscopy of Cl6 inorganic solid electrolyte powder. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] A method for preparing an inorganic solid electrolyte includes the following steps:

[0037] S1, Under air conditions, the reaction raw materials LiCl, AlCl3, and ACl3 are separately added to water and stirred to dissolve, forming a transparent mixed solution. Stirring is performed using magnetic stirring at 100-500 rpm for 10-60 minutes. The concentration of the reaction raw materials in the mixed solution is 0.05-0.2 g / mL. The A in ACl3 is selected from Y... 3+ In 3+One or more of the following; the molar ratio of the reaction raw materials is LiCl:AlCl3:ACl3=a:x:(1-x), 1≤a≤6; 0≤x≤1; preferably, 0.01≤x≤0.3;

[0038] S2, under air conditions, the mixed solution is treated by freeze-drying to obtain Li. a Al x A 1-x Cl a+3 Precursor powder; freeze-drying temperature is -50 to 0℃, vacuum degree is 0.1-20 Pa, and freeze-drying time is 2-24 h; preferably, freeze-drying time is 8-15 h; freeze-drying can remove water from the mixed solution while it is frozen into a solid state, forming a solid powder with smaller average particle size and more uniform particle size distribution. Compared with the traditional synthesis ball milling method, the particle size of the solid powder synthesized by freeze-drying is reduced by 2-3 times. The smaller particle size reduces the porosity of the solid electrolyte; the smaller, more uniform particle size simultaneously improves interfacial contact and reduces interfacial impedance, ultimately leading to an increase in the ionic conductivity of the solid electrolyte.

[0039] S3, under inert gas protection, the precursor powder is calcined at a temperature of 200-550℃, a heating rate of 3-10℃ / min, and a holding time of 2-12 hours to obtain calcined Li. a Al x A 1-x Cl a+x Solid electrolytes; under calcination conditions, bound water in the resulting solid electrolyte precursor powder can be removed, preventing water from causing a decrease in the ionic conductivity of the solid electrolyte. In addition, calcination enhances the structural stability and crystallinity of the formed solid electrolyte, comprehensively promoting an increase in the ionic conductivity of the solid electrolyte.

[0040] S4, under inert gas protection conditions, calcined Li a Al x A 1-x Cl a+x Solid electrolytes were ball-milled at a speed of 400-800 rpm for 0.5-4 hours. The grinding balls had a radius of 5-10 mm and a ball-to-material ratio of 20-40:1 to obtain Li. a Al x A 1-x Cl a+x Solid electrolyte powder. Ball milling can pulverize the sintered solid electrolyte obtained after calcination, further reducing the particle size of the solid electrolyte powder and making the powder more uniform, thereby improving the ionic conductivity of the solid electrolyte. The final Li a Al xA 1-x Cl a+x The particle size of the solid electrolyte powder is 400-800 nm.

[0041] The obtained inorganic solid electrolyte is a crystalline phase, and Al doping alleviates the high cost of rare earth elements in halide solid electrolytes to some extent. Furthermore, due to Al's moisture resistance, the synthesized doped solid electrolyte can recover its ionic conductivity after absorbing water through high-temperature calcination. Therefore, Al doping allows for the use of freeze-drying to synthesize the solid electrolyte, obtaining solid electrolyte powder from an aqueous solvent, and achieving a certain degree of improved conductivity.

[0042] The solution provided by the present invention will be further described below with reference to the embodiments.

[0043] Example 1

[0044] Under air conditions, 1 g of LiCl and InCl3 were weighed according to a LiCl:InCl3 molar ratio of 3:1. The raw materials were added to 10 mL of deionized water and stirred magnetically at 200 rpm for 10 min until completely dissolved, forming a transparent solution of 0.1 g / mL. The transparent solution was freeze-dried at -50℃ and 15 Pa for 12 h to obtain Li3InCl6 precursor powder. Under argon protection, the obtained Li3InCl6 precursor powder was calcined at 200℃ with a heating rate of 3℃ / min and a holding time of 4 h. After calcination, Li3InCl6 solid electrolyte was obtained. Under argon protection, the obtained Li3InCl6 solid electrolyte was ball-milled at 400 rpm for 2 h with a ball-to-material ratio of 20:1 to obtain the final Li3InCl6 powder.

[0045] The XRD pattern of the Li3InCl6 inorganic solid electrolyte powder prepared in this embodiment is shown in the figure. Figure 1 The corresponding impedance spectrum is shown in Figure 2 As shown in the figure, the solid electrolyte prepared in this embodiment has a C2 / m configuration, which corresponds to a twisted monoclinic rock salt structure and is a crystalline phase. The impedance value obtained by electrochemical impedance spectroscopy is 378 Ω, which corresponds to an ionic conductivity of 7.89 × 10⁻⁶. -5 S / cm.

[0046] Example 2

[0047] Under air conditions, 1 g of LiCl, AlCl3, and InCl3 were weighed according to a molar ratio of LiCl:AlCl3:InCl3 = 3:0.05:0.95. The raw materials were added to 10 mL of deionized water and stirred magnetically at 200 rpm for 10 min until completely dissolved, forming a clear solution with a concentration of 0.1 g / mL. The clear solution was then freeze-dried at -50 °C and 15 Pa for 12 h to obtain Li3Al 0.05 In 0.95 Cl6 precursor powder. Under argon protection, the obtained Li3Al... 0.05 In 0.95 Cl6 precursor powder was calcined at 300℃ with a heating rate of 5℃ / min and a holding time of 4 hours. After calcination, Li3Al was obtained. 0.05 In 0.95 Cl6 solid electrolyte. Under argon protection, the obtained Li3Al... 0.05 In 0.95 The Cl6 solid electrolyte was ball-milled at 500 rpm for 1 hour with a ball-to-material ratio of 30:1 to obtain the final Li3Al. 0.05 In 0.95 Cl6 powder.

[0048] The Li3Al prepared in this embodiment 0.05 In 0.95 The XRD pattern of Cl6 inorganic solid electrolyte powder is shown below. Figure 3 The corresponding impedance spectrum is shown in Figure 4 As shown in the figure, the solid electrolyte prepared in this embodiment has a C2 / m configuration, corresponding to a twisted monoclinic rock salt structure, which is a crystalline phase. The impedance value obtained by electrochemical impedance spectroscopy is 61Ω, which corresponds to an ionic conductivity of 5.03 × 10⁻⁶ for this sample. -4 S / cm.

[0049] Example 3

[0050] Under air conditions, 1 g of LiCl, AlCl3, and InCl3 were weighed according to a molar ratio of LiCl:AlCl3:InCl3 = 3:0.1:0.9. The raw materials were added to 10 mL of deionized water and stirred magnetically at 200 rpm for 10 min until completely dissolved, forming a clear solution with a concentration of 0.1 g / mL. The clear solution was then freeze-dried at -50 °C and 15 Pa for 12 h to obtain Li3Al 0.1 In 0.9 Cl6 precursor powder. Under argon protection, the obtained Li3Al... 0.1 In 0.9Cl6 precursor powder was calcined at 300℃ with a heating rate of 5℃ / min and a holding time of 4 hours. After calcination, Li3Al was obtained. 0.1 In 0.9 Cl6 solid electrolyte. Under argon protection, the obtained Li3Al... 0.1 In 0.9 The Cl6 solid electrolyte was ball-milled at 500 rpm for 1 hour with a ball-to-material ratio of 30:1 to obtain the final Li3Al. 0.1 In 0.9 Cl6 powder.

[0051] The Li3Al prepared in this embodiment 0.1 In 0.9 The XRD pattern of Cl6 inorganic solid electrolyte powder is shown below. Figure 5 The corresponding impedance spectrum is shown in Figure 6 As shown in the figure, the solid electrolyte prepared in this embodiment has a C2 / m configuration, which corresponds to a twisted monoclinic rock salt structure and is a crystalline phase. The impedance value obtained by electrochemical impedance spectroscopy is 148 Ω, which corresponds to an ionic conductivity of 2.02 × 10⁻⁶. -4 S / cm.

[0052] Example 4

[0053] Under air conditions, 1 g of LiCl, AlCl3, and InCl3 were weighed according to a molar ratio of LiCl:AlCl3:InCl3 = 3:0.2:0.8. The raw materials were added to 10 mL of deionized water and stirred magnetically at 200 rpm for 10 min until completely dissolved, forming a clear solution with a concentration of 0.1 g / mL. The clear solution was then freeze-dried at -50 °C and 15 Pa for 12 h to obtain Li3Al 0.2 In 0.8 Cl6 precursor powder. Under argon protection, the obtained Li3Al... 0.2 In 0.8 Cl6 precursor powder was calcined at 350℃ with a heating rate of 5℃ / min and a holding time of 4 hours. After calcination, Li3Al was obtained. 0.2 In 0.8 Cl6 solid electrolyte. Under argon protection, the obtained Li3Al... 0.2 In 0.8 The Cl6 solid electrolyte was ball-milled at 500 rpm for 1 hour with a ball-to-material ratio of 30:1 to obtain the final Li3Al. 0.2 In 0.8 Cl6 powder.

[0054] The Li3Al prepared in this embodiment0.2 In 0.8 The XRD pattern of Cl6 inorganic solid electrolyte powder is shown below. Figure 7 The corresponding impedance spectrum is shown in Figure 8 As shown in the figure, the solid electrolyte prepared in this embodiment has a C2 / m configuration, corresponding to a twisted monoclinic rock salt structure, which is a crystalline phase. The impedance value obtained by electrochemical impedance spectroscopy is 91 Ω, which corresponds to an ionic conductivity of 3.28 × 10⁻⁶ for this sample. -4 S / cm.

[0055] Example 5

[0056] Under air conditions, 1 g of LiCl, AlCl3, and InCl3 were weighed according to a molar ratio of LiCl:AlCl3:InCl3 = 3:0.3:0.7. The raw materials were added to 10 mL of deionized water and stirred magnetically at 200 rpm for 10 min until completely dissolved, forming a clear solution with a concentration of 0.1 g / mL. The clear solution was then freeze-dried at -50 °C and 15 Pa for 12 h to obtain Li3Al 0.3 In 0.7 Cl6 precursor powder. Under argon protection, the obtained Li3Al... 0.3 In 0.7 Cl6 precursor powder was calcined at 350℃ with a heating rate of 5℃ / min and a holding time of 4 hours. After calcination, Li3Al was obtained. 0.3 In 0.7 Cl6 solid electrolyte. Under argon protection, the obtained Li3Al... 0.3 In 0.7 The Cl6 solid electrolyte was ball-milled at 500 rpm for 1 hour with a ball-to-material ratio of 30:1 to obtain the final Li3Al. 0.3 In 0.7 Cl6 powder.

[0057] The Li3Al prepared in this embodiment 0.3 In 0.7 The XRD pattern of Cl6 inorganic solid electrolyte powder is shown below. Figure 9 The corresponding impedance spectrum is shown in Figure 10 As shown in the figure, the solid electrolyte prepared in this embodiment has a C2 / m configuration, which corresponds to a twisted monoclinic rock salt structure and is a crystalline phase. The impedance value obtained by electrochemical impedance spectroscopy is 156 Ω, which corresponds to an ionic conductivity of 1.91 × 10⁻⁶ Ω for this sample. -4 S / cm.

[0058] Example 6

[0059] Under air conditions, 1 g of LiCl, AlCl3, and InCl3 were weighed according to a molar ratio of LiCl:AlCl3:InCl3 = 3:0.5:0.5. The raw materials were added to 10 mL of deionized water and stirred magnetically at 200 rpm for 10 min until completely dissolved, forming a clear solution with a concentration of 0.1 g / mL. The clear solution was then freeze-dried at -50 °C and 15 Pa for 12 h to obtain Li3Al 0.5 In 0.5 Cl6 precursor powder. Under argon protection, the obtained Li3Al... 0.5 In 0.5 Cl6 precursor powder was calcined at 350℃ with a heating rate of 5℃ / min and a holding time of 4 hours. After calcination, Li3Al was obtained. 0.5 In 0.5 Cl6 solid electrolyte. Under argon protection, the obtained Li3Al... 0.5 In 0.5 The Cl6 solid electrolyte was ball-milled at 500 rpm for 1 hour with a ball-to-material ratio of 30:1 to obtain the final Li3Al. 0.5 In 0.5 Cl6 powder.

[0060] The Li3Al prepared in this embodiment 0.5 In 0.5 The XRD pattern of Cl6 inorganic solid electrolyte powder is shown below. Figure 11 The corresponding impedance spectrum is shown in Figure 12 As shown in the figure, the solid electrolyte prepared in this embodiment has a C2 / m configuration, which corresponds to a twisted monoclinic rock salt structure and is a crystalline phase. The impedance value obtained by electrochemical impedance spectroscopy is 449 Ω, which corresponds to an ionic conductivity of 6.65 × 10⁻⁶ for this sample. -5 S / cm.

[0061] The key feature of this invention is the use of a water-soluble freeze-drying method, which reduces the preparation cost and time of solid electrolytes and enables mass production compared to conventional ball milling. Simultaneously, elemental doping can be performed during this process, resulting in an electrolyte material with an ionic conductivity of 5.03 × 10⁻⁶. -4 S / cm, which can be used in all-solid-state lithium-ion batteries.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A method for preparing an inorganic solid-state electrolyte, characterized by, Includes the following steps: S1, Under air conditions, the reaction raw materials LiCl, AlCl3, and InCl3 are added to water respectively and stirred to dissolve, forming a transparent mixed solution; the molar ratio of the reaction raw materials is LiCl:AlCl3:InCl3=a:x:(1-x), 1≤a≤6; 0.05≤x≤0.3; the concentration of the reaction raw materials in the mixed solution is 0.05-0.2 g / mL; S2, under air condition, the mixed solution is treated by freeze-drying process to obtain Li a Al x In 1-x Cl a+3 precursor powder; S3, under inert gas protection, calcining the precursor powder, the calcining temperature is 300-550 ℃, the holding time is 2-12 hours, to obtain the calcined Li a Al x In 1-x Cl a+x Solid-state electrolyte S4, under inert gas protection conditions, calcined Li a Al x In 1-x Cl a+x Solid electrolytes are ball-milled at a speed of 400-800 rpm for 0.5-4 hours to obtain Li. a Al x In 1-x Cl a+x Solid electrolyte powder.

2. The method of claim 1, wherein the inorganic solid-state electrolyte is prepared by a process comprising: In step S1, the stirring and dissolving is carried out using magnetic stirring at a speed of 100-500 rpm for a time of 10-60 min. ​ 3. The method of claim 1, wherein the inorganic solid-state electrolyte is prepared by a process comprising: preparing a precursor solution by dissolving a lithium salt in a solvent; and preparing the inorganic solid-state electrolyte by mixing the precursor solution with a lithium metal oxide. In step S2, the freeze-drying temperature is -50 to 0 ℃, the vacuum degree is 0.1-20 Pa, and the freeze-drying time is 2 to 24 h.

4. The method of claim 3, wherein the inorganic solid-state electrolyte is prepared by a process comprising: preparing a precursor solution by dissolving a lithium salt in a solvent; and preparing the inorganic solid-state electrolyte by mixing the precursor solution with a lithium metal oxide. The freeze-drying time is 8-15 hours.

5. The method for preparing inorganic solid electrolytes according to claim 1, characterized in that, The heating rate for calcination is 3-10 °C / min.

6. The method of claim 1, wherein the inorganic solid-state electrolyte is prepared by a process comprising: preparing a precursor solution by dissolving a lithium salt in a solvent; and preparing the inorganic solid-state electrolyte by mixing the precursor solution with a polymer solution. The grinding balls used in the ball mill have a radius of 5-10 mm and a ball-to-material ratio of 20-40:

1.

7. The method of claim 1, wherein the inorganic solid-state electrolyte is prepared by a process comprising: The Li a Al x In 1-x Cl a+x The solid-state electrolyte powder is in a crystalline phase. ​

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