Anti-perovskite solid-state electrolyte, preparation method thereof, solid-state electrolyte sheet and all-solid-state lithium battery

Abstract

The application relates to the technical field of lithium ion batteries, and discloses an inverse perovskite solid electrolyte, a preparation method thereof, a solid electrolyte sheet and a full-solid-state lithium battery. The method uses Li3OX as raw material, and obtains the inverse perovskite solid electrolyte through pretreatment and pressure sintering. The application also discloses the inverse perovskite solid electrolyte prepared by the method, the solid electrolyte sheet comprising the inverse perovskite solid electrolyte, and the full-solid-state battery comprising the solid electrolyte sheet. The application uses Li3OX and optional LiX as raw material, and sintering is carried out under specific conditions, so that the purity of Li7O2X3 (for example, Li7O2Br3) in the obtained inverse perovskite solid electrolyte reaches more than 47%, and the highest value can reach 87%, thereby the ion conductivity of the inverse perovskite solid electrolyte can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a reverse perovskite solid-state electrolyte, a preparation method thereof, a solid-state electrolyte sheet and a full solid-state lithium battery. BACKGROUND

[0002] With the increasing depletion of fossil energy and the increasing environmental pollution, developing new clean and pollution-free renewable energy is the research focus of the world today. Clean energy such as wind energy, solar energy, and tidal energy has irregular distribution in time and space, and needs to be stored to achieve higher utilization efficiency.

[0003] Lithium ion batteries stand out among many energy storage technologies due to their stable charging and discharging, high energy conversion efficiency, and high energy density, and have become a research hotspot in today's energy storage field. However, with the increasing demand for energy storage and daily applications, traditional lithium batteries containing liquid electrolytes have been unable to meet people's demand for higher energy density due to their safety and energy density limitations. Full solid-state lithium batteries using solid-state electrolytes have the characteristics of not being flammable, which can effectively improve the safety of lithium batteries. The use of lithium metal negative electrodes also greatly improves their energy density. Therefore, full solid-state lithium batteries are considered to be the next generation of highly competitive energy storage technology. In addition, as an important component of full solid-state lithium batteries, solid-state electrolytes are required to have high lithium ion conductivity to effectively conduct lithium ions.

[0004] Reverse perovskite structure solid-state electrolytes have attracted widespread attention due to their high lithium ion conductivity, low cost, and good stability to metal lithium. Researchers have made a series of structural designs for reverse perovskite solid-state electrolytes, including introducing defects, introducing molecular clusters, and metal cation doping. Recently, researchers have found that by adjusting the structure, designing a two-dimensional layered reverse perovskite structure can effectively improve the lithium ion conductivity. Theoretical calculations have found that the two-dimensional structure has a relatively soft phonon vibration mode, which can effectively improve the lithium ion conductivity. Experiments have found that the layered Na4OI2 has a lower activation energy than the three-dimensional cubic Na3OBr. First-principle calculations have also found that the layered Li4OBr2 has a low migration barrier of 0.29 eV. However, the specific two-dimensional layered reverse perovskite structure still has problems in experimental synthesis.

[0005] Enhanced Ionic Conductivity with Li7O2Br3 Phase in Li3OBr Anti-Perovskite Solid Electrolyte (Zhu, J.; Li, S.; Zhang, Y.; Howard, J. W.; Lu, X.; Li, Y.; Wang, Y.; Kumar, R. S.; Wang, L.; Zhao, Y.,. APPLIED PHYSICS LETTERS 2016, 109, 61-65.) discloses a Li3OBr anti-perovskite solid electrolyte mixed with Li7O2Br3 by a ball milling method with LiBr and Li2O as raw materials. However, the mass percentage of Li7O2Br3 in the anti-perovskite solid electrolyte is only 44%. The lithium ion conductivity of the anti-perovskite solid electrolyte is 0.24 x 10 -4 S·cm -1 , which is much higher than the lithium ion conductivity (10 -6 S·cm -1 ) of Li3OBr.

[0006] Therefore, it is necessary to provide a method for preparing an anti-perovskite solid electrolyte containing a higher purity of Li7O2Br3. SUMMARY

[0007] The purpose of the present application is to overcome the problem of low purity of Li7O2Br3 in the anti-perovskite solid electrolyte in the prior art, and to provide an anti-perovskite solid electrolyte and a preparation method thereof, a solid electrolyte sheet, and a full solid-state lithium battery.

[0008] To achieve the above purpose, the first aspect of the present application provides a preparation method of an anti-perovskite solid electrolyte, wherein the method uses Li3OX as a raw material, and obtains an anti-perovskite solid electrolyte after pretreatment and pressure sintering.

[0009] wherein X is one or more of F - , Cl - , Br - , I - , NO2 - , NH2 - , BH4 - and BF4 - .

[0010] The second aspect of the present application provides an anti-perovskite solid electrolyte prepared by the method of the first aspect.

[0011] The third aspect of the present application provides a solid electrolyte sheet comprising the anti-perovskite solid electrolyte of the second aspect.

[0012] A fourth aspect of the present invention provides an all-solid-state battery comprising the solid electrolyte sheet described in the third aspect.

[0013] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0014] This invention uses Li3OX and optional LiX as raw materials, and sintersects them under specific conditions to obtain an anti-perovskite solid electrolyte with a purity of Li7O2X3 (e.g., Li7O2Br3) of more than 47%, and up to 87%, thereby improving the ionic conductivity of the anti-perovskite solid electrolyte. Attached Figure Description

[0015] Figure 1 This is the XRD pattern of the anti-perovskite solid electrolyte prepared in Example 3 of the present invention. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] The first aspect of the present invention provides a method for preparing an anti-perovskite solid electrolyte, wherein the method uses Li3OX as raw material, and obtains the anti-perovskite solid electrolyte after pretreatment and sintering;

[0018] Where X is F - Cl - ,Br - I - NO2 - NH2 - BH4 - and BF4 - One or more of them.

[0019] In the preparation process described in this invention, the main reactions that occur when X is Br are as follows:

[0020] 3Li3OBr→Li7O2Br3+Li2O.

[0021] This invention uses Li3OX as a raw material and sintersulates the pretreated raw material under pressure, unexpectedly increasing the purity of Li7O2X3 (e.g., Li7O2Br3) in the prepared anti-perovskite solid electrolyte, that is, increasing the mass percentage of Li7O2X3 (e.g., Li7O2Br3) in the anti-perovskite solid electrolyte. The anti-perovskite solid electrolyte prepared by this invention has improved ionic conductivity.

[0022] In some embodiments of the present invention, the raw material further includes LiX.

[0023] In this invention, the method preferably uses Li3OX and LiX as raw materials, and the reaction that occurs is as follows:

[0024] 2Li3OBr + LiBr → Li7O2Br3.

[0025] The present invention uses Li3OX and LiX as raw materials to further improve the purity of Li7O2X3 (e.g., Li7O2Br3) in the prepared anti-perovskite solid electrolyte to 60-87%, thereby further improving the ionic conductivity of the anti-perovskite solid electrolyte.

[0026] In some preferred embodiments of the present invention, the molar ratio of Li3OX to LiX is 1:0.3-0.9, preferably 1:0.4-0.75. In the present invention, if this molar ratio is too large, the reaction is insufficient and excessive decomposition of Li3OX occurs; if this molar ratio is too small, more LiX is produced, reducing the purity of the product.

[0027] In some preferred embodiments of the present invention, X is Br - .

[0028] In some embodiments of the present invention, the pretreatment includes ball milling and drying Li3OX and optionally LiX. In the present invention, ball milling ensures that the reactants are mixed uniformly.

[0029] In some preferred embodiments of the present invention, the ball milling speed is 150-500 rpm, for example, 150 rpm, 200 rpm, 300 rpm, 400 rpm, 500 rpm, and any value within the range of any two of the above values, preferably 200-300 rpm. In the present invention, if the ball milling speed is too fast, the material will react; if the ball milling speed is too slow, a longer mixing time is required.

[0030] In some preferred embodiments of the present invention, the ball milling time is 0.5-5 hours, for example, 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or any value within the range of any two of the above values, preferably 1-3 hours. In the present invention, if the ball milling time is too short, the mixing will not be uniform enough; if the ball milling time is too long, a uniform mixture will be obtained, but too much unnecessary time will be consumed.

[0031] In some preferred embodiments of the present invention, the drying temperature is 100-180°C, for example 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, and any value within the range of any two of the above values, preferably 120-160°C. In the present invention, if the drying temperature is too low, a longer drying time is required; if the drying temperature is too high, the raw materials may react.

[0032] In some preferred embodiments of the present invention, the drying time is 1-5 hours, preferably 1.5-2.5 hours. In the present invention, if the drying time is too short, the drying effect will not be achieved; if the drying time is too long, too much time will be consumed.

[0033] In some preferred embodiments of the invention, the drying is performed under vacuum conditions. This method prevents moisture from entering.

[0034] In some preferred embodiments of the present invention, the vacuum degree of the vacuum condition is 10. -1 -10 -2 Pa.

[0035] In some embodiments of the present invention, when the method uses Li3OX as raw material, the pressure of the pressure sintering is 4-10 GPa, for example 4 GPa, 5 GPa, 6 GPa, 7 GPa, 8 GPa, 9 GPa, 10 GPa, and any value within the range of any two of the above values, preferably 6-8 GPa.

[0036] In some embodiments of the present invention, when the method uses Li3OX and LiX as raw materials, the pressure of the pressure sintering is 5-9 GPa, for example 5 GPa, 6 GPa, 7 GPa, 8 GPa, 9 GPa, and any value within the range of any two of the above values, preferably 7-7.5 GPa.

[0037] In this invention, if the pressure of the pressure sintering is too low, the yield of Li7O2Br3 will be too low; if the pressure of the pressure sintering is too high, the yield of Li7O2Br3 will also decrease, and the product will decompose.

[0038] In some preferred embodiments of the present invention, the pressure sintering temperature is 550-900℃, for example, 550℃, 600℃, 700℃, 800℃, 900℃, or any value within the range of any two of the above values, preferably 700-800℃. In the present invention, if the pressure sintering temperature is too low, the reaction will not be sufficient; if the pressure sintering temperature is too high, the product will decompose.

[0039] In some preferred embodiments of the present invention, the pressure sintering time is 1.5-5 hours, for example, 1.5 hours, 2 hours, 3 hours, 4 hours, 5 hours, or any value within the range of any two of the above values, preferably 2-3 hours. In the present invention, if the pressure sintering time is too short, the reaction will not be sufficient; if the pressure sintering time is too long, too much synthesis time will be consumed.

[0040] According to some embodiments of the present invention, the method further includes: post-processing the sintered product to obtain an anti-perovskite solid electrolyte.

[0041] Those skilled in the art can choose post-processing methods, such as grinding, according to actual needs.

[0042] According to a particularly preferred embodiment of the present invention, a method for preparing an anti-perovskite solid electrolyte includes the following steps:

[0043] (1) Using Li3OBr and LiBr in a molar ratio of 1:0.4-0.75 as raw materials, ball milling is performed at 200-300 rpm for 1-3 hours, followed by drying at 120-160℃ for 1.5-2.5 hours; the drying is carried out under a vacuum of 10 -1 -10 -2 The procedure was carried out under vacuum conditions of Pa;

[0044] (2) The dried product is sintered at 700-800℃ and 7-7.5GPa for 2-3 hours;

[0045] (3) The sintered product is post-treated to obtain an anti-perovskite solid electrolyte.

[0046] The second aspect of the present invention provides an anti-perovskite solid electrolyte prepared by the method described in the first aspect.

[0047] A third aspect of the present invention provides a solid electrolyte sheet comprising the anti-perovskite solid electrolyte described in the second aspect.

[0048] In this invention, solid electrolyte sheets can be prepared using methods known in the art.

[0049] A fourth aspect of the present invention provides an all-solid-state battery comprising the solid electrolyte sheet described in the third aspect.

[0050] This invention uses Li3OX and optional LiX as raw materials, and sintersects them under specific conditions to obtain an anti-perovskite solid electrolyte with a purity of Li7O2X3 (e.g., Li7O2Br3) of more than 47%, and up to 87%, thereby improving the ionic conductivity of the anti-perovskite solid electrolyte.

[0051] The present invention will be described in detail below through embodiments.

[0052] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0053] Example 1

[0054] This embodiment illustrates the preparation of an anti-perovskite solid electrolyte.

[0055] (1) Weigh 0.15 mol of Li3OBr as raw material in a glove box, put the raw material into a 30 mL ball mill jar containing 60 g of zirconia balls, and ball mill at 200 rpm for 2 h. Then put the material into a vacuum drying oven (vacuum degree of 10). -2 Pa), dried at 160℃ for 2 hours;

[0056] (2) The product obtained in step (1) is placed in the cavity of a six-sided press and sintered for 2 hours at a pressure of 7 GPa and a temperature of 700 °C. After cooling to room temperature, the pressure is released to obtain an anti-perovskite solid electrolyte including Li7O2Br3 and Li3OBr.

[0057] Example 2

[0058] This embodiment illustrates the preparation of an anti-perovskite solid electrolyte.

[0059] (1) Weigh 0.15 mol of Li3OBr as raw material in a glove box, put the raw material into a 30 mL ball mill jar containing 60 g of zirconia balls, and ball mill at 300 rpm for 3 h. Then put the material into a vacuum drying oven (vacuum degree of 10). -2 Pa), dried at 150℃ for 2.5h;

[0060] (2) The product obtained in step (1) is placed in the cavity of a six-sided press and sintered for 2.5 h at a pressure of 6 GPa and a temperature of 750 °C. After cooling to room temperature, the pressure is released to obtain an anti-perovskite solid electrolyte including Li7O2Br3 and Li3OBr.

[0061] Example 3

[0062] This embodiment illustrates the preparation of an anti-perovskite solid electrolyte.

[0063] (1) Weigh 0.1 mol of Li3OBr and 0.05 mol of LiBr as raw materials in a glove box. Place the raw materials into a 30 mL ball mill jar containing 60 g of zirconia balls and ball mill at 200 rpm for 1 h to mix them evenly. Then place the above mixed slurry into a vacuum drying oven (vacuum degree of 10). -2 Pa), dried at 120℃ for 1.5h;

[0064] (2) The product obtained in step (1) is placed in the cavity of a six-sided press and sintered for 3 hours at a pressure of 8 GPa and a temperature of 800 °C. After cooling to room temperature, the pressure is released to obtain an anti-perovskite solid electrolyte including Li7O2Br3 and Li3OBr.

[0065] Example 4

[0066] This embodiment illustrates the preparation of an anti-perovskite solid electrolyte.

[0067] (1) Weigh 0.1 mol of Li3OBr and 0.04 mol of LiBr as raw materials in a glove box. Place the raw materials into a 30 mL ball mill jar containing 60 g of zirconia balls and ball mill at 150 rpm for 5 h to mix them evenly. Then place the above mixed slurry into a vacuum drying oven (vacuum degree of 10). -2 Pa), dried at 100℃ for 1 hour;

[0068] (2) The product obtained in step (1) is placed in the cavity of a six-sided press and sintered for 5 hours at a pressure of 4 GPa and a temperature of 550 °C. After cooling to room temperature, the pressure is released to obtain an anti-perovskite solid electrolyte including Li7O2Br3 and Li3OBr.

[0069] Example 5

[0070] This embodiment illustrates the preparation of an anti-perovskite solid electrolyte.

[0071] (1) Weigh 0.1 mol of Li3OBr and 0.08 mol of LiBr as raw materials in a glove box. Place the raw materials into a 30 mL ball mill jar containing 60 g of zirconia balls and ball mill at 500 rpm for 0.5 h to mix them evenly. Then place the above mixed slurry into a vacuum drying oven (vacuum degree of 10). -2 Pa), dried at 180℃ for 5 hours;

[0072] (2) The product obtained in step (1) is placed in the cavity of a six-sided press and sintered for 1.5 h at a pressure of 10 GPa and a temperature of 900 °C. After cooling to room temperature, the pressure is released to obtain an anti-perovskite solid electrolyte including Li7O2Br3 and Li3OBr.

[0073] Comparative Example 1

[0074] Example 4 disclosed in CN113054246A is used as a comparative example.

[0075] Specifically, the following steps were taken: using cubic inverse perovskite Li3OBr as raw material, with a lithium, oxygen, and bromine molar ratio of 3:1:1, the sample was placed in a crucible for heat treatment at a temperature of 300℃ for 10 minutes. After the heat treatment process, the molten sample was placed in liquid nitrogen for cooling to obtain the inverse perovskite solid electrolyte material.

[0076] Test Example 1

[0077] The purity of Li7O2Br3 in the anti-perovskite solid electrolytes prepared in Examples 1-5 and Comparative Example 1 was analyzed by XRD, and the results are shown in Table 1. The XRD pattern of the anti-perovskite solid electrolyte in Example 3 is shown below. Figure 1 .

[0078] Test Example 2

[0079] The anti-perovskite solid electrolytes prepared in Examples 1-5 and Comparative Example 1 were fabricated into solid electrolyte sheets, and their ionic conductivity was tested. The results are shown in Table 1.

[0080] The method for preparing solid electrolyte sheets is as follows: Take a certain mass of electrolyte powder, grind it thoroughly, spread it evenly in the mold of a tablet press, press it into a tablet with a pressure of 300 MPa, hold the pressure for 5 minutes, and then remove it. The tableting is complete, and a solid electrolyte sheet is obtained. After polishing the solid electrolyte sheet smooth, double-sided gold sputtering is performed to prepare blocking electrodes.

[0081] The method for testing ionic conductivity is as follows: Electrochemical impedance spectroscopy (EIS) was used to test the impedance diagram of the solid electrolyte on an electrochemical workstation. The frequency range was 1 MHz to 0.1 Hz, and the amplitude was 10 mV. Impedance testing was performed at room temperature, and the ionic conductivity was obtained by analyzing and fitting the obtained impedance diagram using Zview software.

[0082] Table 1

[0083]

[0084]

[0085] As can be seen from the results in Table 1, compared with Comparative Example 1, Examples 1-5 using the method of the present invention, with Li3OBr and optional LiBr as raw materials, sintered under specific conditions, achieved a purity of Li7O2Br3 in the obtained anti-perovskite solid electrolyte of more than 47%, and up to 87%, thereby improving the ionic conductivity of the anti-perovskite solid electrolyte.

[0086] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing an anti-perovskite solid electrolyte, characterized in that, The method uses Li3OX as raw material, and after pretreatment and pressure sintering, an anti-perovskite solid electrolyte Li7O2X3 is obtained. Where X is F - Cl - ,Br - I - NO2 - NH2 - BH4 - and BF4 - One or more of the following; When the method uses Li3OX as raw material, the pressure of the pressure sintering is 6-8 GPa; When the method uses Li3OX and LiX as raw materials, the pressure of the pressure sintering is 7-7.5 GPa; The pressure sintering temperature is 700-800℃; The pressure sintering time is 2-3 hours.

2. The method according to claim 1, wherein, The raw materials also include LiX.

3. The method according to claim 1, wherein, The molar ratio of Li3OX to LiX is 1:0.3-0.

9.

4. The method according to claim 3, wherein, The molar ratio of Li3OX to LiX is 1:0.4-0.

75.

5. The method according to claim 1, wherein, X is Br - .

6. The method according to any one of claims 1-5, wherein, The pretreatment includes ball milling and drying of Li3OX and optional LiX.

7. The method according to claim 6, wherein, The ball mill speed is 150-500 rpm; And / or, the ball milling time is 0.5-5 hours.

8. The method according to claim 7, wherein, The ball milling speed is 200-300 rpm; And / or, the ball milling time is 1-3 hours.

9. The method according to claim 6, wherein, The drying temperature is 100-180℃; And / or, the drying time is 1-5 hours.

10. The method according to claim 9, wherein, The drying temperature is 120-160℃; And / or, the drying time is 1.5-2.5 hours.

11. The method according to claim 6, wherein, The drying process is carried out under vacuum conditions.

12. The method according to claim 11, wherein, The vacuum level of the vacuum condition is 10. -1 -10 -2 Pa.

13. The method according to any one of claims 1-5, wherein, The method further includes: post-processing the product obtained by pressure sintering to obtain an anti-perovskite solid electrolyte.

14. An anti-perovskite solid electrolyte prepared by the method of any one of claims 1-13.

15. A solid electrolyte sheet comprising the anti-perovskite solid electrolyte of claim 14.

16. An all-solid-state battery comprising the solid electrolyte sheet of claim 15.

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