A double-halogen doped halide electrolyte and a method of making the same

Abstract

A double-halogen doped halide solid electrolyte and a preparation method thereof, relate to the technical field of lithium ion batteries. The double-halogen doped halide electrolyte has a chemical formula of Li3YBr a Cl 6‑a‑ b X b , wherein X is at least one of F or I, 0 a Cl 6‑a‑b N b ] valence is -6. The Li3YBr2Cl4 is prepared by a wet chemical method, which greatly improves the ionic conductivity of the electrolyte, so that lithium ions have more abundant migration paths in the material; the Li3YBr2Cl4 is doped with fluorine or iodine for modification, which greatly improves the compatibility of the electrolyte with the lithium metal negative electrode interface under the premise of maintaining high ionic conductivity, effectively inhibits the reaction between the lithium metal negative electrode and the interface, so that it can be applied to high-energy-density lithium metal as a negative electrode in a full solid-state battery, which is of great significance for improving the energy density of the full solid-state battery, ensuring the chemical stability and excellent electrical performance of the full solid-state secondary battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a double-halogen doped halide solid electrolyte and a preparation method thereof. BACKGROUND

[0002] With the continuous innovation of global new energy, lithium ion batteries are widely used in electric vehicles and energy storage based on lithium batteries, but still face the development challenges of insufficient energy density and insufficient safety and stability. All-solid-state batteries combine non-flammable solid electrolytes with high-voltage cathodes such as LiCoO2 and NCM series or lithium metal high-capacity electrodes, and achieve high energy density and good thermal stability in energy storage, thereby becoming the focus of research. Solid electrolyte is a core component of all-solid-state batteries, and its ionic conductivity, mechanical deformation and electrochemical stability can directly affect the overall performance of all-solid-state batteries.

[0003] Currently, the common solid electrolytes mainly include oxide and sulfide types. Although the oxide electrolyte has good electrochemical stability, it has poor compatibility with lithium metal, resulting in large interface impedance. Although the sulfide electrolyte has high ionic conductivity, it is easy to react with air to generate toxic hydrogen sulfide gas. Halide solid electrolytes have excellent deformation, high-voltage cathode stability and high lithium ion conductivity, and are widely concerned. Considering the high cost performance of halide solid electrolytes, rare earth elements with abundant reserves, simple preparation and low cost are preferred. Compared with mechanical ball milling, wet chemical method for preparing halide solid electrolytes provides a more efficient, more uniform and more practical possibility for future industrialization, so the study of wet chemical method for preparing Li3YX6(X=F, Cl, Br and I) halide system has good application prospect. However, there are two problems: first, the ionic conductivity of the halide electrolyte of the system is not high, such as the ionic conductivity of LYC is 0.345 mS cm -1 ; second, the interface between yttrium-based halide and lithium metal electrolyte is still a challenge. Patent CN113363567A discloses a method for preparing halide solid electrolyte by wet chemical method, and improves the ionic conductivity of halide to a certain extent. Yu et al. (Yu, et al. Superionic Fluorinated Halide Solid Electrolytes for Highly Stable Li-Metal in All-Solid-State Li Batteries. Advanced Energy Materials 2021, 11(36)) discloses Li3YBr 5.7 F 0.3It has excellent stability to lithium. Unfortunately, there is no report on the preparation of this electrolyte by wet chemical method, which involves the experimental study on the conductivity of yttrium-based halide electrolyte and its stability to lithium metal.

[0004] In summary, there is an urgent need to design an electrolyte which can be prepared by wet chemical method, has high ionic conductivity and enhanced stability to lithium metal, etc., so as to solve the problems of poor lithium metal compatibility, complex preparation and high cost. SUMMARY

[0005] The purpose of the present application is to solve the problems in the background art, and a double-halogen doped halide electrolyte and a preparation method thereof are provided. The halide electrolyte has a high room temperature ionic conductivity (≥2.38 mS / cm), so that the lithium ions have more migration paths in the material; and the electrolyte interface has excellent lithium metal negative electrode interface compatibility, which can inhibit the reaction between the lithium metal negative electrode and the interface. In addition, the double-halogen doped halide solid-state electrolyte has good economy and environmental friendliness, and can be mass-produced by wet chemical method, without using high-cost and low-abundance metal materials, which is expected to promote the large-scale preparation of low-cost solid-state electrolytes and high-capacity all-solid-state batteries, and promote the commercial application of all-solid-state battery technology.

[0006] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0007] A double-halogen doped halide electrolyte, the chemical formula of which is Li3YBr a Cl 6-a-b X b , wherein X is at least one of F or I, 0 a Cl 6-a-b N b ] valence is -6.

[0008] Preferably, the chemical formula of the double-halogen doped halide electrolyte is Li3YBr a Cl 6-a-b F b , Li3YBr a Cl 6-a-b I b or Li3YBr a Cl 6-a-b (FI) b .

[0009] Further, the surface of the double-halogen doped halide electrolyte is a microstructure of non-oriented stripe arrangement, the stripe length is 1-2.4 μm, and the stripe spacing is 40-60 nm.

[0010] Further, the anion arrangement of the double-halogen doped halide electrolyte is hexagonal close packing or cubic close packing.

[0011] A preparation method of a double-halogen doped halide electrolyte, comprising the following steps:

[0012] S1. In the ethanol solvent of NH4Cl, YCl3·6H2O is added, and it is moved to a magnetic heating stirring platform to mix uniformly at 40-60℃, 500-800rpm / min, to obtain solution A;

[0013] S2. LiCl and LiBr are added to deionized water, and it is moved to a magnetic heating stirring platform to mix uniformly at 40-60℃, 500-800rpm / min, to obtain solution B; solution A and solution B are mixed uniformly to obtain solution C;

[0014] S3. A 10 -5 mol / L LiOH solution is added dropwise in solution C, the PH is adjusted to 7-8, then LiF or LiI is added, and it is mixed uniformly to obtain solution D;

[0015] S4. Solution D is moved to a vacuum drying box, and vacuum drying is carried out at 85-120℃ for 24-72 hours to obtain a precursor block;

[0016] S5. The precursor block is ground into a powder, and is pressed into a round sheet under a pressure of 2-4 tons;

[0017] S6. The round sheet is heat treated in an argon environment at 350-600℃ for 5 hours to obtain the halide electrolyte.

[0018] Further, when NH4Cl, YCl3·6H2O, LiCl, LiBr, LiF are used as raw materials, the molar ratio of NH4Cl, YCl3·6H2O, LiCl, LiBr, LiF is 3:1:1-x:2:x, 0

[0019] When NH4Cl, YCl3·6H2O, LiCl, LiBr, LiI are used as raw materials, the molar ratio of NH4Cl, YCl3·6H2O, LiCl, LiBr, LiI is 3:1:1-x:2:x, 0

[0020] Further, in step S3, LiF and LiI can be added at the same time, at this time, only LiBr is used in S2, and the molar ratio of NH4Cl, YCl3·6H2O, LiBr, LiF, LiI is 3:1:y:x:3-x-y, 0

[0021] The application also provides application of the above-mentioned double-halogen doped halide electrolyte in an electrolyte or an electrode interface additive in a solid-state secondary battery.

[0022] Compared with the prior art, the application has the following beneficial effects:

[0023] 1. The application provides a double-halogen doped halide electrolyte and a preparation method thereof, Li3YBr2Cl4 is prepared by using a wet chemical method, the ionic conductivity of the electrolyte is greatly improved (3.04 mS cm -1 ), so that lithium ions have more migration paths in the material; the Li3YBr2Cl4 is doped and modified by fluorine or iodine, the compatibility of the electrolyte with a lithium metal negative electrode interface is greatly improved on the premise of maintaining high ionic conductivity (2.38 mS cm -1 ), the reaction between the lithium metal negative electrode and the interface is effectively inhibited, so that the electrolyte can be applied to a full solid-state battery with high energy density and a lithium metal as a negative electrode, and has important significance for improving the energy density of the full solid-state battery and ensuring the chemical stability and excellent electrical performance of the full solid-state secondary battery.

[0024] 2. The application provides a double-halogen doped halide electrolyte and a preparation method thereof, the process is simple, the wet chemical method is beneficial to large-scale preparation of the material, so that the material is no longer limited to a glove box environment, and has good economic efficiency and environmental friendliness; only Y, a metal material with low cost and high abundance, is used, the cost is low, and the large-scale preparation of a low-cost solid-state electrolyte and a high-capacity full solid-state battery can be promoted, and commercial application of the full solid-state battery technology can be promoted. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is Li3YBr2Cl 3.7 F 0.3 and an XRD pattern (a) and a local enlarged view (b and c) of the prepared Li3YBr2Cl4 halide solid-state electrolyte;

[0026] Figure 2 is Li3YBr2Cl 3.7 F 0.3 SEM micro-morphology of the prepared Li3YBr2Cl4 halide solid-state electrolyte;

[0027] Figure 3 is Li3YBr2Cl 3.7 F 0.3 0.1 mA cm-2 constant current cycle test diagram (a) and a local enlarged view (b) of the lithium pair battery of the prepared Li3YBr2Cl4 halide solid-state electrolyte; -2

[0028] Figure 4 is Li3YBr2Cl​3.7 F 0.3 Impedance test curves obtained after sintering with Li3YBr2Cl4 solid electrolyte material at the annealing temperature. Detailed Implementation

[0029] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0030] Example 1

[0031] This embodiment provides a halide solid electrolyte with the chemical formula Li3YBr2Cl. 3.7 F 0.3 The preparation method is as follows:

[0032] S1: In a glove box, weigh out 1 mol YCl3·6H2O, 0.7 mol LiCl, 3 mol NH4Cl, 2 mol LiBr and 0.3 mol LiF by molar ratio. Transfer the weighed NH4Cl to a beaker and add anhydrous ethanol until it is fully dissolved. Then add the weighed YCl3·6H2O to the beaker and transfer it to a magnetic heating stirring platform. Stir at 40℃ and 600 r / min for 30 minutes to obtain solution A.

[0033] S2: Add LiCl and LiBr to the deionized water solvent, transfer to a magnetic heating stirring platform and mix them evenly at 40℃ and 600 rpm / min to obtain solution B; add solution A to solution B and mix evenly to obtain solution C;

[0034] S3: Add a solution of concentration 10 to solution C. -5 Adjust the pH of the mol / L LiOH solution to 7-8, add the weighed LiF, and stir at 600 r / min for 30 minutes until it is mixed evenly to obtain solution D;

[0035] S4: Transfer solution D to a vacuum drying oven and dry it under vacuum at 120°C for 48 hours to obtain the precursor block;

[0036] S5: Grind the precursor block into powder and press it into a block under a pressure of 2 tons;

[0037] S6: The bulk material is heat-treated at 450°C for 5 hours to obtain the halide solid electrolyte.

[0038] Example 2

[0039] Example 2 differs from Example 1 in that the annealing temperature of step S6 is adjusted to 500°C, and the remaining steps are the same as Example 1.

[0040] Example 3

[0041] Example 3 differs from Example 1 in that the annealing temperature of step S6 is adjusted to 550°C, and the remaining steps are the same as Example 1.

[0042] Example 4

[0043] The present embodiment provides a halide solid-state electrolyte with a chemical formula of Li3YBr2Cl3I1, and a preparation method as follows:

[0044] S1: In a glove box, first, 1 mol of YCl3·6H2O, 3 mol of NH4Cl, 2 mol of LiBr, and 1 mol of LiI are weighed according to the molar ratio, and the weighed NH4Cl is moved to a beaker and anhydrous ethanol is added until it is fully dissolved. Then, the weighed YCl3·6H2O is added to the beaker and moved to a magnetic heating and stirring platform, and stirred at a speed of 40°C and 600 r / min for 30 minutes to obtain solution A;

[0045] S2: LiCl and LiBr are added to deionized water solvent, moved to a magnetic heating and stirring platform, and mixed uniformly at a speed of 40°C and 600 rpm / min to obtain solution B; solution A is added to solution B and mixed uniformly to obtain solution C;

[0046] S3: In solution C, 10 -5 mol / L of LiOH solution is added dropwise, the PH is adjusted to 7-8, the weighed LiI is added, and stirred at a speed of 600 r / min for 30 minutes until it is mixed uniformly to obtain solution D;

[0047] S4: Solution D is moved to a vacuum drying oven and vacuum dried at 120°C for 48 hours to obtain a precursor block;

[0048] S5: The precursor block is ground into a powder and pressed into a block under a pressure of 2 tons;

[0049] S6: The block is heat treated at 450°C for 5 hours to obtain the halide solid-state electrolyte.

[0050] Example 5

[0051] Example 5 differs from Example 4 in that the annealing temperature of step S6 is adjusted to 500°C, and the remaining steps are the same as Example 4.

[0052] Example 6

[0053] Example 6 differs from Example 4 in that the annealing temperature of step S6 is adjusted to 550℃, and the remaining steps are the same as Example 4.

[0054] Example 7

[0055] This example provides a halide solid-state electrolyte with a chemical formula of Li3YBr2Cl 3.9 F 0.1 , and the preparation method is as follows:

[0056] S1: In a glove box, first, 1 mol of YCl3·6H2O, 0.9 mol of LiCl, 3 mol of NH4Cl, 2 mol of LiBr, and 0.1 mol of LiF are weighed according to the molar ratio, and the weighed NH4Cl is moved to a beaker and anhydrous ethanol is added until it is fully dissolved. Then, the weighed YCl3·6H2O is added to the beaker and moved to a magnetic heating and stirring platform, and stirred at a speed of 40℃ and 600r / min for 30 minutes to obtain solution A;

[0057] S2: LiCl and LiBr are added to deionized water solvent, moved to a magnetic heating and stirring platform, and mixed uniformly at 40℃ and 600rpm / min to obtain solution B; solution A is added to solution B and mixed uniformly to obtain solution C;

[0058] S3: A 10 -5 mol / L LiOH solution is added dropwise to solution C, the pH is adjusted to 7-8, the weighed LiF is added, and stirred at a speed of 600r / min for 30 minutes until it is mixed uniformly to obtain solution D;

[0059] S4: Solution D is moved to a vacuum drying box and vacuum dried at 120℃ for 48 hours to obtain a precursor block;

[0060] S5: The precursor block is ground into powder and pressed into a block under a pressure of 2 tons;

[0061] S6: The block is heat treated at 450℃ for 5 hours to obtain the halide solid-state electrolyte.

[0062] Example 8

[0063] This example provides a halide solid-state electrolyte with a chemical formula of Li3YBr2Cl 3.5 F 0.5 , and the preparation method is as follows:

[0064] S1: In a glove box, first, 1 mol of YCl3·6H2O, 0.5 mol of LiCl, 3 mol of NH4Cl, 2 mol of LiBr, and 0.5 mol of LiF are weighed according to the molar ratio, the weighed NH4Cl is moved to a beaker and anhydrous ethanol is added until it is fully dissolved, then the weighed YCl3·6H2O is added to the beaker and moved to a magnetic heating and stirring platform, stirred at 40°C and 600 r / min for 30 minutes to obtain solution A;

[0065] S2: LiCl and LiBr are added to deionized water solvent, moved to a magnetic heating and stirring platform, mixed uniformly at 40°C and 600 rpm / min to obtain solution B; solution A is added to solution B and mixed uniformly to obtain solution C;

[0066] S3: A 10 -5 mol / L LiOH solution is added dropwise to solution C, the pH is adjusted to 7-8, the weighed LiF is added, and stirred at 600 r / min for 30 minutes until it is mixed uniformly to obtain solution D;

[0067] S4: Solution D is moved to a vacuum drying oven and vacuum dried at 120°C for 48 hours to obtain a precursor block;

[0068] S5: The precursor block is ground into powder and pressed into a block under a pressure of 2 tons;

[0069] S6: The block is heat treated at 450°C for 5 hours to obtain the halide solid-state electrolyte.

[0070] Example 9

[0071] This example provides a halide solid-state electrolyte with a chemical formula of Li3YBr2Cl 3.3 F 0.7 , and the preparation method is as follows:

[0072] S1: In a glove box, first, 1 mol of YCl3·6H2O, 0.5 mol of LiCl, 3 mol of NH4Cl, 2 mol of LiBr, and 0.5 mol of LiF are weighed according to the molar ratio, the weighed NH4Cl is moved to a beaker and anhydrous ethanol is added until it is fully dissolved, then the weighed YCl3·6H2O is added to the beaker and moved to a magnetic heating and stirring platform, stirred at 40°C and 600 r / min for 30 minutes to obtain solution A;

[0073] S2: LiCl and LiBr are added to deionized water solvent, moved to a magnetic heating and stirring platform, mixed uniformly at 40°C and 600 rpm / min to obtain solution B; solution A is added to solution B and mixed uniformly to obtain solution C;

[0074] S3: drop 10 mol / L LiOH solution into solution C, adjust PH to 7-8, add weighed LiF, and stir at 600 r / min for 30 minutes until it is mixed evenly to obtain solution D; -5

[0075] S4: move solution D to a vacuum drying oven and vacuum dry at 120°C for 48 hours to obtain a precursor block;

[0076] S5: grind the precursor block into powder and press into a block under a pressure of 2 tons;

[0077] S6: heat treat the block at 450°C for 5 hours to obtain the halide solid-state electrolyte.

[0078] Example 10

[0079] This example provides a halide solid-state electrolyte with a chemical formula of Li3YBr2Cl3F1, and the preparation method is as follows:

[0080] S1: in a glove box, first weigh 1 mol YCl3·6H2O, 3 mol NH4Cl, 2 mol LiBr, and 1 mol LiF according to the molar ratio, move the weighed NH4Cl to a beaker and add anhydrous ethanol until it is fully dissolved, then add the weighed YCl3·6H2O to the beaker and move it to a magnetic heating and stirring platform, stir at 40°C and 600 r / min for 30 minutes to obtain solution A;

[0081] S2: add LiCl and LiBr to deionized water solvent, move to a magnetic heating and stirring platform, mix evenly at 40°C and 600 rpm / min to obtain solution B; add solution A to solution B and mix evenly to obtain solution C;

[0082] S3: drop 10 mol / L LiOH solution into solution C, adjust PH to 7-8, add weighed LiF, and stir at 600 r / min for 30 minutes until it is mixed evenly to obtain solution D; -5

[0083] S4: move solution D to a vacuum drying oven and vacuum dry at 120°C for 48 hours to obtain a precursor block;

[0084] S5: grind the precursor block into powder and press into a block under a pressure of 2 tons;

[0085] S6: heat treat the block at 450°C for 5 hours to obtain the halide solid-state electrolyte.

[0086] ​​Other embodiments are not described again.

[0087] It should be noted that the present application is not limited to the specific embodiments described above, and various modifications or changes can be made by those skilled in the art within the scope of the claims, and the essential content of the present application is not affected.

Claims

1. A dual-halogen-doped halide electrolyte, characterized in that, The chemical formula of the halide electrolyte is Li3YBr. a Cl 6-a-b X b , where X is at least one of F or I, 0 < a < 3, 0 < b < 3, a + b ≤ 3; The preparation process of the dual-halogen-doped halide electrolyte is as follows: S1. Add YCl3·6H2O to the ethanol solvent of NH4Cl, stir and mix well to obtain solution A; S2. Add LiCl and LiBr to deionized water and stir to mix thoroughly to obtain solution B; mix solution A and solution B thoroughly to obtain solution C; S3. Add LiOH solution dropwise to solution C, adjust the pH to 7-8, then add LiF or LiI, mix well to obtain solution D; S4. Dry solution D under vacuum at 85℃~120℃ to obtain precursor block; S5. Grind the precursor block into powder and press it into shape; S6. The formed blank is heat-treated at 350-600°C in an argon atmosphere to obtain the halide electrolyte.

2. The dual-halogen-doped halide electrolyte according to claim 1, characterized in that, The surface of the dual-halogen-doped halide electrolyte has a microstructure with non-oriented stripe arrangement, the stripe length is 1μm to 2.4μm, and the stripe spacing is 40nm to 60nm.

3. The dual-halogen-doped halide electrolyte according to claim 1, characterized in that, The anion arrangement of the dihalogen-doped halide electrolyte is hexagonal close-packed or cubic close-packed.

4. A method for preparing a dual-halogen-doped halide electrolyte as described in claim 1, characterized in that, Includes the following steps: S1. Add YCl3·6H2O to the ethanol solvent of NH4Cl, stir and mix well to obtain solution A; S2. Add LiCl and LiBr to deionized water and stir to mix thoroughly to obtain solution B; mix solution A and solution B thoroughly to obtain solution C; S3. Add LiOH solution dropwise to solution C, adjust the pH to 7-8, then add LiF or LiI, mix well to obtain solution D; S4. Dry solution D under vacuum at 85℃~120℃ to obtain precursor block; S5. Grind the precursor block into powder and press it into shape; S6. The formed blank is heat-treated at 350-600°C in an argon atmosphere to obtain the halide electrolyte.

5. The method for preparing a dual-halogen-doped halide electrolyte according to claim 4, characterized in that, When NH4Cl, YCl3·6H2O, LiCl, LiBr, and LiF are used as raw materials, the molar ratio of NH4Cl, YCl3·6H2O, LiCl, LiBr, and LiF is 3:1:1-x:2:x, where 0 < x < 1. When NH4Cl, YCl3·6H2O, LiCl, LiBr, and LiI are used as raw materials, the molar ratio of NH4Cl, YCl3·6H2O, LiCl, LiBr, and LiI is 3:1:1-x:2:x, where 0 < x < 1.

6. The method for preparing a dual-halogen-doped halide electrolyte according to claim 4, characterized in that, In step S3, LiF and LiI are added simultaneously. At this time, the raw materials in S2 are only LiBr. The molar ratio of NH4Cl, YCl3·6H2O, LiBr, LiF and LiI is 3:1:y:x:3-xy, 0<x<1, 1<y<2.

7. The use of the dual-halogen-doped halide electrolyte according to any one of claims 1 to 3 as an electrolyte or electrode interface additive in a solid-state secondary battery.

8. The use of the dual-halogen-doped halide electrolyte prepared by the method of any one of claims 4 to 6 as an electrolyte or electrode interface additive in a solid-state secondary battery.

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