Oxidation halide solid electrolyte and preparation method thereof

Abstract

The invention discloses a preparation method of an oxyhalide solid electrolyte, the chemical general formula of the oxyhalide solid electrolyte is LixLayZr2Cl3y + 8O2x (x = 1-8, y = 1-4), the oxyhalide solid electrolyte provided by the invention has ionic conductivity greater than 1mS cm <-1 > at room temperature, the cost of required materials is low, the preparation process is simple, and the preparation method is suitable for industrial production. In addition, the material also has a wide electrochemical window (1.25-4.77 V), and has a good industrial production prospect.

Description

Technical Field

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

[0002] With the steady economic growth and the accelerating industrialization process, the global demand for energy has shown a sharp growth trend. However, the reserves of traditional energy resources such as oil and coal are decreasing day by day, and their limited nature cannot meet the long-term needs of mankind's continued prosperity and development. The use of fossil fuels has also led to a continuous increase in carbon dioxide emissions, and the global climate change situation has become increasingly severe. Therefore, we need to actively explore and develop new energy sources to meet the challenges of current and future energy supply. Countries around the world pay more attention to promoting the transformation of the energy industry from fossil energy to clean energy. The conversion and storage of energy has attracted widespread attention from people from all walks of life, and the energy storage industry will continue to develop rapidly in the future.

[0003] Oxyhalide solid electrolytes have various advantages of halides, and on this basis, they have better air stability and higher ionic conductivity, which has attracted much attention. LiTaOCl4 has a conductivity of 12.4 mS cm at room temperature. -1 The high ionic conductivity of Ta metal is high, but Ta metal is expensive and not suitable for large-scale production; a series of oxyhalides of Li2ZrCl6 are low-cost, but the long-term ball milling limits the large-scale production to a certain extent, so the development of new low-cost oxyhalides is extremely important. Summary of the invention

[0004] The present invention aims to provide a halogen oxide solid electrolyte and a preparation method thereof, which is not only simple to prepare but also has an ionic conductivity greater than 1 mS cm at room temperature. -1 The required raw materials Li2O, ZrCl4 and LaCl3 are extremely low in price and have good prospects in industrial production.

[0005] The present invention provides a halide solid electrolyte, the chemical formula of which is Li x La y Zr2Cl 3y+8 O 2x (x=1-8, y=1-4).

[0006] Li x La y Zr2Cl 3y+8 O 2x The diffraction peak is single phase and the structure is UCl3 type.

[0007] The halide electrolyte material includes Li6La4Zr2Cl 20O3、Li4La3Zr2Cl 17 O2、Li6La3Zr2Cl 17 O3、Li4La2Zr2Cl 14 O2、Li6La2Zr2Cl 14 O3、Li4LaZr2Cl 11 O2、Li6LaZr2Cl 11 O3、Li8LaZr2Cl 11 O4.

[0008] The ionic conductivity of the oxyhalide solid electrolyte material is ≥0.3 mS cm -1 .

[0009] The invention provides a method for preparing a halide solid electrolyte. Under the protection of an inert gas, corresponding masses of Li2O, LaCl3 and ZrCl4 raw materials are weighed according to the atomic ratio of the halide solid electrolyte, and the raw materials are uniformly ground and then mechanically ball-milled to obtain a halide electrolyte. The ball-to-material mass ratio of the mechanical ball milling is 10-80:1; the ball milling time is 4-60 h; and the ball milling speed is 400 rpm-1100 rpm.

[0010] In summary, the present invention provides a new oxyhalide solid electrolyte material, which has good ionic conductivity at room temperature, and the ionic conductivity at room temperature is greater than 1 mS cm -1 The electrochemical window is wide, the required materials are low-cost, the preparation process is simple, and it can meet the requirements of large-scale production, with good prospects for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The X-ray diffraction analysis spectrum of the oxyhalide solid electrolyte material obtained in the embodiment; Figure 2 ion conductivity spectrum of the oxyhalide solid electrolyte material prepared in the example; Figure 3 is the LSV curve of the oxyhalide solid electrolyte prepared in Example 7; Figure 4 This is the long cycle curve of the oxyhalide solid electrolyte full battery prepared in Example 7. DETAILED DESCRIPTION

[0012] The present invention will be further described below in conjunction with specific implementation modes.

[0013] The raw materials used in the present invention include commercially available anhydrous Li2O, LaCl3, and ZrCl4 products, with a purity of ≥99.9%.

[0014] Example 1: Li6La4Zr2Cl 20O3 In an argon-filled glove box, accurately weigh 0.0585 g of anhydrous Li2O, 0.6382 g of anhydrous LaCl3 and 0.3033 g of anhydrous ZrCl4, grind and mix them, and then mechanically mill the resulting product, which is Li6La4Zr2Cl 20 For O3 material, the mechanical ball milling ball-to-material mass ratio was 10:1; the ball milling time was 6 h; and the ball milling speed was 1000 rpm.

[0015] Example 2: Li4La3Zr2Cl 17 O2 In an argon-filled glove box, accurately weigh 0.0475 g of anhydrous Li2O, 0.5831 g of anhydrous LaCl3 and 0.3694 g of anhydrous ZrCl4, grind and mix them, and then mechanically mill the resulting product, which is Li4La3Zr2Cl 17 For O2 material, the mechanical ball milling ball-to-material mass ratio was 20:1; the ball milling time was 10 h; and the ball milling speed was 500 rpm.

[0016] Example 3: Li6La3Zr2Cl 17 O3 In an argon-filled glove box, accurately weigh 0.0697 g of anhydrous Li2O, 0.5695 g of anhydrous LaCl3 and 0.3608 g of anhydrous ZrCl4, grind and mix them, and then mechanically mill the resulting product, which is Li6La3Zr2Cl 17 For O3 material, the mechanical ball milling ball-to-material mass ratio was 10:1; the ball milling time was 10 h; and the ball milling speed was 800 rpm.

[0017] Example 4: Li4La2Zr2Cl 14 O2 In an argon-filled glove box, accurately weigh 0.1114 g of anhydrous Li2O, 0.4556 g of anhydrous LaCl3 and 0.4330 g of anhydrous ZrCl4, grind and mix them, and then mechanically mill the resulting product, which is Li4La2Zr2Cl 14 For O2 material, the ball-to-material mass ratio of mechanical ball milling was 20:1; the ball milling time was 4 h; and the ball milling speed was 400 rpm.

[0018] Example 5: Li6La2Zr2Cl 14 O3 In an argon-filled glove box, accurately weigh 0.0859 g of anhydrous Li2O, 0.4687 g of anhydrous LaCl3 and 0.4454 g of anhydrous ZrCl4, grind and mix them, and then mechanically mill the resulting product, which is Li6La2Zr2Cl 14 For O3 material, the ball-to-material mass ratio of mechanical ball milling was 10:1; the ball milling time was 20 h; and the ball milling speed was 700 rpm.

[0019] Example 6: Li4LaZr2Cl 14 O2 In an argon-filled glove box, accurately weigh 0.0777 g of anhydrous Li2O, 0.3180 g of anhydrous LaCl3 and 0.6043 g of anhydrous ZrCl4, grind and mix them, and then mechanically mill the resulting product, which is Li4LaZr2Cl 14 For O2 material, the mechanical ball milling ball-to-material mass ratio was 20:1; the ball milling time was 15 h; and the ball milling speed was 800 rpm.

[0020] Example 7: Li6LaZr2Cl 14 O3 In an argon-filled glove box, accurately weigh 0.1122 g of anhydrous Li2O, 0.3061 g of anhydrous LaCl3 and 0.5817 g of anhydrous ZrCl4, grind and mix them, and then mechanically mill the resulting product, which is Li4LaZr2Cl 14 For O3 material, the mechanical ball milling ball-to-material mass ratio was 60:1; the ball milling time was 5 h; and the ball milling speed was 800 rpm.

[0021] In an argon-filled glove box, accurately weigh 0.0777 g of anhydrous Li2O, 0.3180 g of anhydrous LaCl3 and 0.6043 g of anhydrous ZrCl4, grind and mix them, and then mechanically mill the resulting product, which is Li4LaZr2Cl 14 For O2 material, the mechanical ball milling ball-to-material mass ratio was 20:1; the ball milling time was 4 h; and the ball milling speed was 800 rpm.

[0022] Example 8: Li8LaZr2Cl 14 O4 In an argon-filled glove box, accurately weigh 0.1443 g of anhydrous Li2O, 0.2950 g of anhydrous LaCl3 and 0.5607 g of anhydrous ZrCl4, grind and mix them, and then mechanically mill the resulting product, which is Li8LaZr2Cl 14 For O4 material, the mechanical ball milling ball-to-material mass ratio was 30:1; the ball milling time was 15 h; and the ball milling speed was 1000 rpm.

[0023] The following tests were performed on the halide solid electrolyte of the above embodiment: 1) X-ray diffraction test Test method: 150 mg of each of Examples 1-8 was taken, and X-ray diffraction was used to characterize the diffraction peaks and other information of the prepared solid electrolyte, and the test range was 10-80°.

[0024] 2) Lithium ion conductivity test Test method: Take 200 mg of the sample of the above embodiment in a glove box and press it into a sheet in a mold with a diameter of 12 mm. Stick indium sheets on both sides of the sheet as ion blocking electrodes. The impedance is tested by electrochemical impedance spectroscopy (EIS), and the lithium ion conductivity σ=d / (RS) is finally obtained by the formula, where σ is the lithium ion conductivity, d is the thickness of the electrolyte sheet, R is the impedance, and S is the contact area between the blocking electrode and the electrolyte sheet.

[0025] 3) Linear sweep voltammetry (LSV) test The electrochemical oxidation stability potential was measured by linear voltammetry, with the cell configuration being: blocking electrode / electrolyte and carbon mixture / electrolyte / Li6PS5Cl / lithium, with a scan rate of 5 mV / s and a voltage range of open circuit voltage (1.5) to 5 V. The LSV test only involved the oxyhalide solid electrolyte of Example 7.

[0026] 4) All-solid-state battery long cycle performance test Test method: 40 mg of electrolyte was placed in a 10 mm PEEK mold and pressed into a sheet. Then 5 mg of the composite positive electrode was attached to it and pressed into shape with 1 ton of pressure. To prevent the electrolyte from reacting with lithium metal, 60 mg of Li6PS5Cl was pressed into the other side of the electrolyte with 3 tons of pressure. The test was conducted on the Xinwei system with a voltage range of 2-4.3 V.

[0027] Figure 1 3 is the X-ray diffraction analysis spectrum of the oxyhalide solid electrolyte material prepared in the examples; the diffraction peaks of Examples 1-8 are consistent with the LaCl3 standard card and belong to the UCl3 configuration.

[0028] Figure 2 The ionic conductivity spectrum of the oxyhalide solid electrolyte material prepared in the examples; Example 7 has the highest ionic conductivity, and the ionic conductivity of the other examples is greater than 0.3 mS cm -1 .

[0029] Figure 3 The LSV curve of the oxyhalide solid electrolyte prepared in Example 7, we first tested the open circuit voltage (1.5V) of Example 7, and then scanned from the open circuit voltage to 0V and 5V. The electrochemical window was 1.25-4.77V, proving that this example has good stability.

[0030] Figure 4 The long cycle curve of the oxyhalide solid electrolyte full battery prepared in Example 7 is shown at 1C (current density 180.7 mA g -1 ) can stably cycle 100 times under the condition of high temperature, showing good cycle stability.

[0031] The ionic conductivity and activation energy results of Examples 1 to 8 are recorded in Table 1.

[0032] As can be seen from the table above, Example 7 has the highest ionic conductivity (more than 1 mS cm -1 ) and the lowest activation energy, the ionic conductivity of other embodiments is greater than 0.3 mS cm -1 , combined with the high oxidation stability of this embodiment within the test range of LSV, it shows that the method of the present application has industrial prospects.

Claims

1. A halide oxide solid electrolyte, characterized in that: Its chemical formula is Li x La y Zr2Cl 3y+8 O 2x , where x=1-8,y=1-4; Preparation method of oxyhalide solid electrolyte: Under the protection of inert gas, weigh corresponding masses of Li2O, LaCl3, and ZrCl4 raw materials according to the atomic ratio of the halide solid electrolyte, grind them evenly, and then mechanically ball mill them to obtain a halide electrolyte.

2. The oxyhalide solid electrolyte according to claim 1, characterized in that: Li x La y Zr2Cl 3y+8 O 2x The diffraction peak is single phase and the structure is UCl3 type.

3. The oxyhalide solid electrolyte according to claim 1, characterized in that: The ball-to-material mass ratio of mechanical ball milling is 10-80:1; the ball milling time is 4-60 h; and the ball milling speed is 400 rpm-1100 rpm.

4. The oxyhalide solid electrolyte according to any one of claims 1 to 3, characterized in that: The ionic conductivity of the oxyhalide solid electrolyte is ≥ 0.3 mS cm -1 .

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