A halide solid electrolyte and its preparation method and application

Abstract

The present invention provides a halide solid electrolyte and its preparation method and application. The preparation method comprises the following steps: (1) mixing a metal halide, a lithium halide and an organic amine compound to obtain a eutectic precursor; (2) heat-treating the eutectic precursor in an oxygen-free environment to obtain the halide solid electrolyte. The present invention first utilizes the intermolecular interaction of the raw material components to obtain a eutectic precursor that is uniformly mixed at the molecular level. The precursor can then be directly heat-treated to obtain a halide solid electrolyte without introducing other processing steps. Therefore, the preparation method simplifies the preparation process, avoids tedious preparation steps, reduces energy consumption and time costs, shortens the cycle, and significantly improves production efficiency. In addition, the raw materials used are environmentally friendly and inexpensive. The preparation method has good universality and is conducive to large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium batteries, and in particular relates to a halide solid electrolyte and a preparation method and application thereof. Background Art

[0002] Using solid electrolytes to replace traditional organic electrolytes can achieve a dual improvement in the energy density and safety of lithium-ion batteries. After years of research, domestic and foreign researchers have developed a variety of inorganic solid electrolytes, mainly including oxide solid electrolytes, sulfide solid electrolytes and halide solid electrolytes. Among them, oxide solid electrolytes have a wide operating temperature range and a wide electrochemical stability window, but their mechanical plasticity is poor, and a thermal sintering step is usually required in the construction of all-solid-state batteries. Sulfide solid electrolytes have good mechanical ductility and high room temperature ionic conductivity, but their stability in the air is poor, and they react with water and release toxic hydrogen sulfide gas. In addition, the researchers have demonstrated through calculations and experiments that the sulfide solid electrolyte has a low intrinsic electrochemical stability window, and that it requires a protective coating to match the 4V high-voltage oxide positive electrode.

[0003] Halide solid electrolytes have high room temperature ionic conductivity (>10 -4 S cm -1 ), a wide electrochemical window (0.36-6.71V vs. Li+ / Li), and good plasticity. Furthermore, halide solid electrolytes are well compatible with high-voltage cathode materials, helping to improve the energy density of all-solid-state batteries. Therefore, halide solid electrolytes are suitable for use in all-solid-state lithium batteries and have unique development potential.

[0004] At present, the synthesis method of halide solid electrolyte is generally solid phase synthesis method, which has the problems of long cycle, complicated preparation process and high cost. Patent CN111640979A discloses a method of preparing solid electrolyte material Li by high temperature eutectic or room temperature ball milling strategy. a Ho b However, high-temperature eutectic and room-temperature ball milling usually consume a lot of energy and time, and have disadvantages such as long preparation time, high energy consumption, and low efficiency. In addition, the preparation cost is high and the experimental environment is demanding, which is not conducive to large-scale production.

[0005] In addition, the liquid phase synthesis method can also realize the preparation of halide solid electrolytes. However, in the operating process of the currently developed liquid phase method, a drying step (including natural drying, vacuum drying and freeze drying) is usually required to realize the transformation from liquid phase to solid phase. The drying process makes the preparation process cumbersome, increases energy consumption and time cost. Patent CN115642297A discloses a halide solid electrolyte and its preparation method, and specifically discloses that the chemical formula of the halide solid electrolyte is Li 3-x In 1-x Zr x Cl6, where x = 0.01-0.5. In this preparation method, alcohol is used as a solvent. After the raw materials are evenly mixed, the halide electrolyte precursor is obtained after the alcohol is completely evaporated. This method has poor universality and is only suitable for preparing halide solid electrolytes containing In and Zr metals. It also has a long cycle and high cost.

[0006] Therefore, there is an urgent need to design a low-cost, high-efficiency and universal method for preparing halide solid electrolytes. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the object of the present invention is to provide a halide solid electrolyte and its preparation method and application. The present invention first utilizes the intermolecular interaction of the raw material components to obtain a low-melting eutectic precursor with uniform mixing at the molecular level. The precursor can then be directly heat-treated to obtain a halide solid electrolyte without introducing other processing steps. Therefore, the preparation method simplifies the preparation process, avoids tedious preparation steps, reduces energy consumption and time costs, shortens the cycle, and significantly improves production efficiency. In addition, the raw materials used are environmentally friendly and inexpensive. The preparation method has good universality and is conducive to large-scale production.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing a halide solid electrolyte, the preparation method comprising the following steps:

[0010] (1) mixing a metal halide, a lithium halide, and an organic amine compound to obtain a eutectic precursor;

[0011] (2) heat-treating the eutectic precursor in an oxygen-free environment to obtain the halide solid electrolyte.

[0012] The present invention first utilizes the intermolecular interactions of the raw material components to obtain a eutectic precursor with uniform molecular mixing. This precursor can then be directly heat-treated to produce a halide solid electrolyte without the need for additional processing steps. Therefore, this preparation method simplifies the preparation process, avoids cumbersome preparation steps, reduces energy consumption and time costs, shortens the cycle time, and significantly improves production efficiency. Furthermore, the raw materials used are environmentally friendly and inexpensive.

[0013] The preparation method provided by the present invention has good universality and is conducive to large-scale production.

[0014] In the present invention, the organic amine compound helps to form a eutectic.

[0015] As a preferred technical solution of the present invention, the metal element in the metal halide in step (1) includes any one or a combination of at least two of Sc, Y, lanthanide, Zr, Al, Ga, In, Hf, Bi, Mn, Fe, Cd, Mg or Pb.

[0016] Preferably, the lithium halide in step (1) includes any one of lithium fluoride, lithium chloride, lithium bromide or lithium iodide, or a combination of at least two thereof.

[0017] Preferably, the organic amine compound in step (1) includes any one or a combination of at least two of methylamine, ethylamine, carbonamide, triethanolamine, tripropylamine, isopropylamine, octylamine or aniline.

[0018] As a preferred technical solution of the present invention, the molar ratio of the metal halide, lithium halide and organic amine compound in step (1) is (0.5-2):3:(5-10), wherein the selection range of the metal halide "0.5-2" can be, for example, 0.5, 1, 1.5 or 2, and the selection range of the organic amine compound "5-10" can be, for example, 5, 6, 7, 8, 9 or 10.

[0019] In the present invention, if the molar ratio of the metal halide to the organic amine compound is too small, that is, the amount of the organic amine compound is too much, a uniform eutectic cannot be formed; if the molar ratio of the metal halide to the organic amine compound is too large, that is, the amount of the organic amine compound is too little, the metal halide cannot be completely dissolved to form a eutectic.

[0020] As a preferred technical solution of the present invention, a flux is also added during the mixing process in step (1).

[0021] Preferably, the flux includes any one of water, ethanol, methanol, ammonia water or acetic acid, or a combination of at least two of them.

[0022] In the present invention, the flux easily forms hydrogen bonds, thereby facilitating the formation of the eutectic precursor.

[0023] As a preferred technical solution of the present invention, the molar ratio of the metal halide, lithium halide, organic amine compound and flux is (0.5-2):3:(5-10):(0-5), wherein the selection range of the metal halide "0.5-2" can be, for example, 0.5, 1, 1.5 or 2, the selection range of the organic amine compound "5-10" can be, for example, 5, 6, 7, 8, 9 or 10, and the selection range of the flux "0-5" can be, for example, 0, 1, 2, 3, 4 or 5, etc.

[0024] As a preferred technical solution of the present invention, the mixing process in step (1) is accompanied by stirring.

[0025] Preferably, heating is performed during the mixing process in step (1), and the heating method includes oil bath heating.

[0026] Preferably, the heating temperature is 50-200°C, for example, 50°C, 100°C, 150°C or 200°C, etc., preferably 80-150°C.

[0027] In the present invention, if the heating temperature is too low, the eutectic cannot be completely melted to form a homogeneous eutectic; if the heating temperature is too high, the organic amine compound and the flux will decompose, resulting in the presence of impurities.

[0028] Preferably, the heating time is 5 min-2 h, for example, 5 min, 10 min, 30 min, 1 h, 1.5 h or 2 h.

[0029] As a preferred technical solution of the present invention, the gas in the oxygen-free environment in step (2) includes nitrogen and / or argon.

[0030] Preferably, the temperature of the heat treatment in step (2) is 200-800°C, for example, 200°C, 400°C, 600°C or 800°C, and preferably 300-650°C.

[0031] In the present invention, if the heat treatment temperature is too low, impurities may exist in the product; if the heat treatment temperature is too high, the target product may not be obtained.

[0032] Preferably, the heat treatment time in step (2) is 0.5-5 h, for example, 1 h or 3.5 h.

[0033] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0034] (1) placing a metal halide, a lithium halide, an organic amine compound, and a flux in a container at a molar ratio of (0.5-2):3:(5-10):(0-5), stirring and mixing them by heating in an oil bath at a temperature of 50-200° C. for 5 min-2 h to obtain a eutectic precursor;

[0035] (2) placing the eutectic precursor in an oxygen-free environment, performing a heat treatment at 200-800° C. for 0.5-5 h, and then cooling to room temperature to obtain the halide solid electrolyte.

[0036] In a second aspect, the present invention provides a halide solid electrolyte, which is prepared using the preparation method described in the first aspect.

[0037] In a third aspect, the present invention provides a use of the halide solid electrolyte as claimed in claim 9 in a lithium-ion battery.

[0038] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The present invention first utilizes the intermolecular interactions of the raw material components to obtain a low-melting eutectic precursor with uniform mixing at the molecular level. The precursor can then be directly heat-treated to obtain a halide solid electrolyte without introducing other processing steps. Therefore, this preparation method simplifies the preparation process, avoids tedious preparation steps, reduces energy consumption and time costs, shortens the cycle, and significantly improves production efficiency. In addition, the raw materials used are environmentally friendly and inexpensive.

[0041] (2) The preparation method provided by the present invention has good universality and is conducive to large-scale production.

[0042] (3) The halide solid electrolyte prepared based on the preparation method provided by the present invention has a high ionic conductivity (such as room temperature ionic conductivity>1.0mS / cm). BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is the X-ray diffraction peak (XRD) spectrum of Li3YCl6 prepared in Example 1 of the present invention.

[0044] Figure 2 This is the X-ray diffraction peak (XRD) spectrum of Li3HoCl6 prepared in Example 7 of the present invention. DETAILED DESCRIPTION

[0045] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0046] It should be noted that the room temperature below refers to 25°C.

[0047] Example 1

[0048] This embodiment provides a method for preparing a halide solid electrolyte, the preparation method comprising the following steps:

[0049] (1) Yttrium chloride, lithium chloride, and carbonamide were placed in a sealed container at a molar ratio of 1:3:7, and stirred and mixed by heating in an oil bath at a temperature of 100° C. for 1 h to obtain a transparent eutectic precursor;

[0050] (2) placing the eutectic precursor in an argon atmosphere tubular furnace, performing a heat treatment at 500° C. for 2 h, and then cooling to room temperature to obtain the halide solid electrolyte, whose chemical formula is Li3YCl6.

[0051] Figure 1 The X-ray diffraction peak (XRD) spectrum of Li3YCl6 prepared in this example is shown. As can be seen from the figure, the characteristic X-ray diffraction peaks of the prepared halide solid electrolyte are consistent with those of the standard card, and there are no other impurities, indicating that the product is pure phase Li3YCl6.

[0052] Example 2

[0053] This embodiment provides a method for preparing a halide solid electrolyte, the preparation method comprising the following steps:

[0054] (1) Yttrium chloride, lithium chloride, carbonamide, and water were placed in a sealed container at a molar ratio of 1:3:7:5, and stirred and mixed by heating in an oil bath at 80°C for 2 h to obtain a transparent eutectic precursor;

[0055] (2) placing the eutectic precursor in an argon atmosphere tubular furnace, performing a heat treatment at 500° C. for 2 h, and then cooling to room temperature to obtain the halide solid electrolyte, whose chemical formula is Li3YCl6.

[0056] Example 3

[0057] This embodiment provides a method for preparing a halide solid electrolyte, the preparation method comprising the following steps:

[0058] (1) Yttrium chloride, lithium chloride, carbonamide, and water were placed in a sealed container at a molar ratio of 1:3:7:1, and stirred and mixed by heating in an oil bath at a temperature of 200° C. for 5 min to obtain a transparent eutectic precursor;

[0059] (2) placing the eutectic precursor in an argon atmosphere tubular furnace, performing a heat treatment at 500° C. for 2 h, and then cooling to room temperature to obtain the halide solid electrolyte, whose chemical formula is Li3YCl6.

[0060] Example 4

[0061] This embodiment provides a method for preparing a halide solid electrolyte, the preparation method comprising the following steps:

[0062] (1) Yttrium chloride, lithium chloride, carbonamide, and water were placed in a sealed container at a molar ratio of 0.5:3:7:1, and stirred and mixed by heating in an oil bath at a temperature of 120° C. for 1 h to obtain a transparent eutectic precursor;

[0063] (2) placing the eutectic precursor in an argon atmosphere tubular furnace, performing a heat treatment at 500° C. for 2 h, and then cooling to room temperature to obtain the halide solid electrolyte, whose chemical formula is Li3YCl6.

[0064] Example 5

[0065] This embodiment provides a method for preparing a halide solid electrolyte, the preparation method comprising the following steps:

[0066] (1) Yttrium chloride, lithium chloride, carbonamide, and water were placed in a sealed container at a molar ratio of 1.5:3:7:1, and stirred and mixed by heating in an oil bath at a temperature of 200° C. for 5 min to obtain a transparent eutectic precursor;

[0067] (2) placing the eutectic precursor in an argon atmosphere tubular furnace, performing a heat treatment at 500° C. for 2 h, and then cooling to room temperature to obtain the halide solid electrolyte, whose chemical formula is Li3YCl6.

[0068] Example 6

[0069] This embodiment provides a method for preparing a halide solid electrolyte, the preparation method comprising the following steps:

[0070] (1) Yttrium chloride, lithium chloride, carbonamide, and water were placed in a sealed container at a molar ratio of 2:3:7:1, and stirred and mixed by heating in an oil bath at a temperature of 120° C. for 1 h to obtain a transparent eutectic precursor;

[0071] (2) placing the eutectic precursor in an argon atmosphere tubular furnace, performing a heat treatment at 500° C. for 2 h, and then cooling to room temperature to obtain the halide solid electrolyte, whose chemical formula is Li3YCl6.

[0072] Example 7

[0073] This embodiment provides a method for preparing a halide solid electrolyte, the preparation method comprising the following steps:

[0074] (1) Holmium chloride, lithium chloride, and carbonamide were placed in a sealed container at a molar ratio of 1.5:3:8, and stirred and mixed by heating in an oil bath at 80°C for 2 h to obtain a transparent eutectic precursor;

[0075] (2) placing the eutectic precursor in an argon atmosphere tubular furnace, performing a heat treatment at 500° C. for 2 h, and then cooling to room temperature to obtain the halide solid electrolyte, whose chemical formula is Li 3 HoCl 6 .

[0076] Figure 2 This is the X-ray diffraction peak (XRD) spectrum of Li3HoCl6 prepared in this example. As can be seen from the figure, the characteristic X-ray diffraction peaks of the prepared halide solid electrolyte are consistent with the standard card, and there are no other impurities, indicating that the product is pure phase Li3HoCl6.

[0077] Example 8

[0078] This embodiment provides a method for preparing a halide solid electrolyte, the preparation method comprising the following steps:

[0079] (1) Yttrium chloride, holmium chloride hexahydrate, lithium chloride, and carbonamide were placed in a sealed container at a molar ratio of 1:0.5:3:8, and stirred and mixed by heating in an oil bath at a temperature of 100° C. for 2 h to obtain a transparent eutectic precursor;

[0080] (2) placing the eutectic precursor in an argon atmosphere tube furnace, performing a heat treatment at 500°C for 2 hours, and then cooling to room temperature to obtain the halide solid electrolyte, whose chemical formula is Li3Y 2 / 3 Ho 1 / 3 Cl6.

[0081] Example 9

[0082] The difference between this embodiment and embodiment 1 is that the molar ratio of yttrium chloride, lithium chloride and carbonamide in step (1) is 1:3:25.

[0083] The rest of the preparation methods and parameters remained the same as in Example 1.

[0084] Example 10

[0085] The difference between this embodiment and embodiment 1 is that the molar ratio of yttrium chloride, lithium chloride and carbonamide in step (1) is 1:3:2.

[0086] The rest of the preparation methods and parameters remained the same as in Example 1.

[0087] Example 11

[0088] The difference between this embodiment and embodiment 1 is that the heating temperature in step (1) is 30°C.

[0089] The rest of the preparation methods and parameters remained the same as in Example 1.

[0090] Example 12

[0091] The difference between this embodiment and embodiment 1 is that the heating temperature in step (1) is 300°C.

[0092] The rest of the preparation methods and parameters remained the same as in Example 1.

[0093] Example 13

[0094] The difference between this embodiment and embodiment 1 is that the temperature of the heat treatment in step (2) is 100°C.

[0095] The rest of the preparation methods and parameters remained the same as in Example 1.

[0096] Example 14

[0097] The difference between this embodiment and embodiment 1 is that the temperature of the heat treatment in step (2) is 900°C.

[0098] The rest of the preparation methods and parameters remained the same as in Example 1.

[0099] Comparative Example 1

[0100] The difference between this comparative example 1 and embodiment 1 is that no carbonamide is added in step (1).

[0101] The rest of the preparation methods and parameters remained the same as in Example 1.

[0102] Performance Testing

[0103] The halide solid electrolytes prepared in the above examples and comparative examples were subjected to phase tests and lithium ion conductivity tests.

[0104] The test results are shown in Table 1.

[0105] Table 1

[0106]

[0107] “ / ” indicates that the ionic conductivity of the halide solid electrolyte is much less than 1.0 mS / cm.

[0108] analyze:

[0109] As can be seen from the above examples, comparative examples, and Table 1, the preparation method provided by the present invention simplifies the preparation process, avoids tedious preparation steps, reduces energy consumption and time costs, shortens the cycle, and significantly improves production efficiency. In addition, the raw materials used are environmentally friendly and inexpensive. The halide solid electrolyte prepared based on this method is pure phase and has high lithium ion conductivity.

[0110] It can be seen from Examples 1 and 9-10 that if the molar ratio of yttrium chloride, lithium chloride and carbonamide is too small, that is, the amount of carbonamide used is too much, a homogeneous eutectic cannot be obtained, and the ionic conductivity is much less than 1.0 mS / cm; if the molar ratio of yttrium chloride, lithium chloride and carbonamide is too large, that is, the amount of carbonamide used is too little, a homogeneous eutectic cannot be obtained, and the ionic conductivity is much less than 1.0 mS / cm.

[0111] It can be seen from Example 1 and Examples 11-12 that if the heating temperature in step (1) is too low, a homogeneous eutectic cannot be obtained, and the ionic conductivity is much less than 1.0 mS / cm; if the heating temperature in step (1) is too high, the product has an impurity phase and the ionic conductivity is much less than 1.0 mS / cm.

[0112] It can be seen from Example 1 and Examples 13-14 that if the temperature of the heat treatment in step (2) is too low, the product will have an impurity phase and the ionic conductivity will be much less than 1.0 mS / cm; if the temperature of the heat treatment in step (2) is too high, the product will have an impurity phase and the ionic conductivity will be much less than 1.0 mS / cm.

[0113] It can be seen from Example 1 and Comparative Example 1 that if carbonamide is not added in step (1), a homogeneous eutectic cannot be obtained and the ionic conductivity is much less than 1.0 mS / cm.

[0114] The applicant states that while the above-described embodiments illustrate the process of the present invention, the present invention is not limited to the above-described process steps, nor does it imply that the present invention must rely on the above-described process steps for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for the raw materials used, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a halide solid electrolyte, characterized in that: The preparation method comprises the following steps: (1) Mixing metal halide, lithium halide and organic amine compound to obtain a eutectic precursor; (2) heat-treating the eutectic precursor in an oxygen-free environment to obtain the halide solid electrolyte; The metal element in the metal halide in step (1) includes any one or a combination of at least two of Sc, Y, lanthanide, Zr, Al, Ga, In, Hf, Bi, Mn, Fe, Cd, Mg or Pb; The organic amine compound in step (1) includes any one of methylamine, ethylamine, carbonamide, triethanolamine, tripropylamine, isopropylamine, octylamine or aniline, or a combination of at least two thereof.

2. The preparation method according to claim 1, characterized in that The lithium halide in step (1) includes any one of lithium fluoride, lithium chloride, lithium bromide or lithium iodide, or a combination of at least two of them.

3. The preparation method according to claim 1, characterized in that The molar ratio of the metal halide, lithium halide and organic amine compound in step (1) is (0.5-2):3:(5-10).

4. The preparation method according to claim 1, characterized in that During the mixing process of step (1), a flux is also added.

5. The preparation method according to claim 4, characterized in that The flux includes any one of water, ethanol, methanol, ammonia water or acetic acid, or a combination of at least two of them.

6. The preparation method according to claim 1, characterized in that The molar ratio of the metal halide, lithium halide, organic amine compound and flux is (0.5-2):3:(5-10):(0-5).

7. The preparation method according to claim 1, characterized in that The mixing process in step (1) is accompanied by stirring.

8. The preparation method according to claim 1, characterized in that Heating is performed during the mixing process in step (1), and the heating method includes oil bath heating.

9. The preparation method according to claim 8, characterized in that The heating temperature is 50-200°C.

10. The preparation method according to claim 9, characterized in that The heating temperature is 80-150°C.

11. The preparation method according to claim 8, characterized in that The heating time is 5 min-2 h.

12. The preparation method according to claim 1, characterized in that The gas in the oxygen-free environment in step (2) includes nitrogen and / or argon.

13. The preparation method according to claim 1, characterized in that The temperature of the heat treatment in step (2) is 200-800°C.

14. The preparation method according to claim 13, characterized in that The temperature of the heat treatment is 300-650°C.

15. The preparation method according to claim 1, characterized in that The heat treatment time in step (2) is 0.5-5h.

16. The preparation method according to claim 1, characterized in that The preparation method comprises the following steps: (1) According to the molar ratio of (0.5-2):3:(5-10):(0-5), metal halide, lithium halide, organic amine compound and flux are placed in a container, stirred and mixed by heating in an oil bath at a temperature of 50-200°C for a heating time of 5 min-2 h to obtain a eutectic precursor; (2) placing the eutectic precursor in an oxygen-free environment, performing a heat treatment at 200-800° C. for 0.5-5 h, and then cooling it to room temperature to obtain the halide solid electrolyte.

17. A halide solid electrolyte, characterized in that: The halide solid electrolyte is prepared by the preparation method according to any one of claims 1 to 16.

18. Use of the halide solid electrolyte according to claim 17 in a lithium ion battery.

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