A halide solid electrolyte material and its preparation method and application

Abstract

The present invention discloses a halide solid electrolyte material and a preparation method and application thereof, wherein the molecular formula is A 2+x ZrCl 6‑z C z , wherein 0<x≤1, 0<z≤1, A is Li or Na, and C is O or S. The ionic conductivity of the present invention is greater than 1×10 ‑3 S cm ‑1 , has good oxidation resistance, and the synthesis process is simple. The halide electrolyte provided has excellent performance and has good prospects for large-scale industrial production.

Description

Technical Field

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

[0002] Lithium-ion batteries are currently widely used in consumer electronics, electric vehicles, and static energy storage devices. However, lithium-ion batteries contain flammable organic electrolytes, which make them less safe, and battery fires and explosions occur from time to time. Solid-state batteries replace flammable organic electrolytes with non-flammable solid electrolytes, which greatly improves the safety of batteries and has therefore attracted widespread attention. As the core of solid-state batteries, solid electrolytes play a key role in the performance of batteries. Solid-state electrolytes need to meet the following characteristics: high ionic conductivity, low electronic conductivity, wide electrochemical window, low cost, air stability, etc.

[0003] At present, solid electrolytes mainly include polymers, sulfides, NASICON type, Garnet type, halides and other types. As a recently emerging type of electrolyte, halide solid electrolytes have good oxidation resistance and moderate mechanical properties, which have attracted widespread attention. The halide electrolytes disclosed in the prior art mainly include Li 3 E 6 , Li 3 oeLh 6 , Li 3 InCl 6 , Li 3-x M 1-x Zr x Cl 6 (M=Y,Er,Yb),Li x ScCl 3+x It can be seen that the above halides all use low-abundance elements, making it difficult for the above material systems to achieve large-scale application. Recently, CN112591793A and Nature Communications (2021) 12, 4410 reported a low-cost halide solid electrolyte Li 2 ZrCl 6 , which has a good application prospect. However, its room temperature ionic conductivity is relatively low, at 8.1×10 -4 S cm -1 , needs to be further improved. Summary of the invention

[0004] The present invention aims to overcome the defects of the prior art and provide a halide solid electrolyte material.

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned halide solid electrolyte material.

[0006] Another object of the present invention is to provide an application of the above-mentioned halide solid electrolyte material.

[0007] The technical solution of the present invention is as follows:

[0008] A halide solid electrolyte material, the molecular formula of which is A 2+x ZrCl 6-z C z , wherein 0<x≤1, 0<z≤1, A is Li or Na, and C is O or S.

[0009] In a preferred embodiment of the present invention, 0.2≤x≤0.5, 0.2≤z≤0.5, and A is Li.

[0010] More preferably, its molecular formula is Li 2.2 ZrCl 5.8 S 0.2 , Li 2.5 ZrCl 5.5 S 0.5 or Li 2.2 ZrCl 5.8 O 0.2 .

[0011] The preparation method of the above-mentioned halide solid electrolyte material comprises weighing LiCl, Li 2 S\Li 2 O and ZrCl 4 , and then mix and perform high-energy ball milling to obtain the product. The rotation speed of the high-energy ball mill is 400-600rpm, the time is 18-20h, and the ball-to-material ratio is 45-55:1.

[0012] In a preferred embodiment of the present invention, the inert gas atmosphere is an argon atmosphere.

[0013] In a preferred embodiment of the present invention, the high energy ball milling is performed using zirconium oxide balls.

[0014] In a preferred embodiment of the present invention, the high energy ball milling has a rotation speed of 500 rpm, a time of 20 h, and a ball-to-material ratio of 50:1.

[0015] Application of the above-mentioned halide solid electrolyte material in the preparation of solid-state batteries.

[0016] A solid-state battery comprising the above-mentioned halide solid electrolyte material.

[0017] In a preferred embodiment of the present invention, both the positive electrode and the electrolyte layer have the halide solid electrolyte material.

[0018] The beneficial effects of the present invention are:

[0019] 1. The ionic conductivity of the present invention is greater than 1×10 -3 S cm -1 , and has good oxidation resistance; the reasons for the improvement of ion conductivity of the present invention are mainly two aspects, one is the increase of carrier concentration, and the other is the introduction of elements with larger radius or weaker electronegativity, which makes the lithium ion transmission path wider and the interaction force with surrounding anions smaller, thereby accelerating the lithium ion transmission rate; and the reason for oxidation resistance is that the Cl - It has a strong ability to attract electrons, so it is difficult for it to lose electrons.

[0020] 2. The synthesis process of the present invention is simple, the halide electrolyte provided has excellent performance, and has good prospects for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is Li in Example 1 of the present invention 2.2 ZrCl 5.8 S 0.2 Ionic conductivity test results of solid electrolyte materials.

[0022] Figure 2 Li is used in Example 1 of the present invention 2.2 ZrCl 5.8 S 0.2 The charge and discharge curves of batteries assembled with solid electrolyte materials.

[0023] Figure 3 is Li in Example 2 of the present invention 2.5 ZrCl 5.5 S 0.5 Ionic conductivity test results of solid electrolyte materials.

[0024] Figure 4 Li is used in Example 2 of the present invention 2.5 ZrCl 5.5 S 0.5 The charge and discharge curves of batteries assembled with solid electrolyte materials.

[0025] Figure 5 is Li in Example 3 of the present invention 2.2 ZrCl 5.8 O 0.2 Ionic conductivity test results of solid electrolyte materials.

[0026] Figure 6 Li is used in Example 3 of the present invention 2.2 ZrCl 5.8 O 0.2 The charge and discharge curves of batteries assembled with solid electrolyte materials.

[0027] Figure 7 Li in Comparative Example 1 2 ZrCl 6 Ionic conductivity test results of solid electrolyte materials.

[0028] Figure 8 For the use of Li in Comparative Example 1 2 ZrCl 6 The charge and discharge curves of batteries assembled with solid electrolyte materials.

[0029] Fig. 9 It is a comparison chart of the cycle performance of the batteries in Examples 1 and 3 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further illustrated and described below through specific implementation modes in combination with the accompanying drawings.

[0031] Example 1

[0032] This embodiment is Li 2.2 ZrCl 5.8 S 0.2 Preparation, ionic conductivity and electrochemical performance testing of solid electrolyte materials.

[0033] Li 2.2 ZrCl 5.8 S 0.2 The preparation process of solid electrolyte materials is as follows:

[0034] In an argon atmosphere glove box, LiCl, Li 2 S, ZrCl 4 The mixture was added into a high-energy ball milling jar, and then zirconium oxide ball milling beads were added for high-energy ball milling. The rotation speed of the high-energy ball milling was 500 rpm, the ball milling time was 20 hours, and the mixed ball-to-material ratio was 50:1. After the ball milling was completed, the electrolyte powder was collected in an argon atmosphere glove box to obtain the electrolyte powder.

[0035] The prepared Li 2.2 ZrCl 5.8 S 0.2 The halide solid electrolyte material is tested for ionic conductivity. The experimental operation is as follows:

[0036] In an argon atmosphere glove box, the prepared Li 2.2 ZrCl 5.8 S 0.2 The solid electrolyte material is pressed into a sheet, and then carbon-coated aluminum foil is placed on both sides of the electrolyte sheet. Pressure is applied again to ensure good contact between the carbon-coated aluminum foil and the electrolyte sheet. Finally, the AC impedance test is performed. The test results are as follows: Figure 1As shown. By fitting the measured impedance curve, we can get Li 2.2 ZrCl 5.8 S 0.2 The ionic conductivity of halide solid electrolyte materials is: 1.8×10 -3 S cm -1 .

[0037] The prepared Li 2.2 ZrCl 5.8 S 0.2 The electrochemical performance test of the halide solid electrolyte material is carried out as follows:

[0038] LiCoO2 and Li 2.2 ZrCl 5.8 S 0.2 The halide solid electrolyte material is ground with an agate mortar to obtain a uniformly mixed composite positive electrode material. The electrolyte layer uses a Li 2.2 ZrCl 5.8 S 0.2 (positive electrode measurement) and Li 7 P 3 S 11 (negative electrode test) double-layer electrolyte. The negative electrode uses a Li-In alloy negative electrode. The positive and negative electrodes and the electrolyte layer are pressed to obtain a solid-state battery. Finally, the electrochemical performance is tested. The test results are as follows Figure 2 and Fig. 9 The battery has a discharge capacity of 185.2 mAh / g in the voltage range of 2.2-4.0 V, and a capacity retention rate of 90.9% after 15 cycles.

[0039] Example 2

[0040] This embodiment is Li 2.5 ZrCl 5.5 S 0.5 Preparation, ionic conductivity and electrochemical performance testing of solid electrolyte materials.

[0041] Li 2.5 ZrCl 5.5 S 0.5 The preparation process of solid electrolyte materials is as follows:

[0042] In an argon atmosphere glove box, LiCl, Li 2 S, ZrCl 4 The mixture was added into a high-energy ball milling jar, and then zirconium oxide ball milling beads were added for high-energy ball milling. The rotation speed of the high-energy ball milling was 500 rpm, the ball milling time was 20 hours, and the mixed ball-to-material ratio was 50:1. After the ball milling was completed, the electrolyte powder was collected in an argon atmosphere glove box to obtain the electrolyte powder.

[0043] The same ionic conductivity and electrochemical performance test scheme as in Example 1 was used. Figure 3 As shown, we can get Li 2.5 ZrCl 5.5 S 0.5 The ionic conductivity of halide solid electrolyte materials is: 1×10 -3 S cm -1 . Electrochemical properties such as Figure 4 As shown in the figure, the battery has a discharge capacity of 171.7 mAh / g in the voltage range of 2.2-4.0 V.

[0044] Example 3

[0045] This embodiment is Li 2.2 ZrCl 5.8 o 0.2 Preparation, ionic conductivity and electrochemical performance testing of solid electrolyte materials.

[0046] Li 2.2 ZrCl 5.8 O 0.2 The preparation process of solid electrolyte materials is as follows:

[0047] In an argon atmosphere glove box, LiCl, Li 2 O, ZrCl 4 The mixture was added into a high-energy ball milling jar, and then zirconium oxide ball milling beads were added for high-energy ball milling. The rotation speed of the high-energy ball milling was 500 rpm, the ball milling time was 20 hours, and the mixed ball-to-material ratio was 50:1. After the ball milling was completed, the electrolyte powder was collected in an argon atmosphere glove box to obtain the electrolyte powder.

[0048] The same ionic conductivity and electrochemical performance test scheme as in Example 1 was used. Figure 5 As shown, we can get Li 2.2 ZrCl 5.8 O 0.2 The ionic conductivity of halide solid electrolyte materials is: 1×10 -3 S cm -1 . Electrochemical properties such as Figure 6 and Fig. 9 The battery has a discharge capacity of 192.3 mAh / g in the voltage range of 2.2-4.0 V, and a capacity retention rate of 92.0% after 15 cycles.

[0049] Comparative Example 1

[0050] This comparative example is Li 2 ZrCl 6 Preparation, ionic conductivity and electrochemical performance testing of solid electrolyte materials.

[0051] Li 2 ZrCl 6 The preparation process of solid electrolyte materials is as follows:

[0052] In an argon atmosphere glove box, LiCl, ZrCl 4 The mixture was added into a high-energy ball milling jar, and then zirconium oxide ball milling beads were added for high-energy ball milling. The rotation speed of the high-energy ball milling was 500 rpm, the ball milling time was 20 hours, and the mixed ball-to-material ratio was 50:1. After the ball milling was completed, the electrolyte powder was collected in an argon atmosphere glove box to obtain the electrolyte powder.

[0053] The same ionic conductivity and electrochemical performance test scheme as in Example 1 was used. Figure 7 As shown, we can get Li 2 ZrCl 6 The ionic conductivity of halide solid electrolyte material is: 0.68×10 -3 S cm -1 . Electrochemical properties such as Figure 8 and Fig. 9 The battery has a discharge capacity of 181.8 mAh / g in the voltage range of 2.2-4.0 V, and a capacity retention rate of 85.4% after 15 cycles.

[0054] The technical effect of the present invention can be seen from the above embodiments and comparative examples: by optimizing various experimental conditions, the halide solid electrolyte material provided by the present invention has higher ionic conductivity and better electrochemical performance than the comparative example, and therefore has good application prospects.

[0055] The above description is only a preferred embodiment of the present invention, and therefore cannot be used to limit the scope of the present invention. That is, equivalent changes and modifications made according to the patent scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A halide solid electrolyte material, characterized in that: Its molecular formula is Li 2+x ZrCl 6-z S z , where 0<x≤1, 0<z≤1.

2. A halide solid electrolyte material according to claim 1, characterized in that: 0.2≤x≤0.5, 0.2≤z≤0.

5.

3. A halide solid electrolyte material according to claim 2, characterized in that: Its molecular formula is Li 2.2 ZrCl 5.8 S 0.2 or Li 2.5 ZrCl 5.5 S 0.5 .

4. The method for preparing the halide solid electrolyte material according to any one of claims 1 to 3, characterized in that: Under an inert gas atmosphere, LiCl, Li2S and ZrCl4 are weighed according to the stoichiometric ratio, and then mixed and high-energy ball milled to obtain the product. The rotation speed of the high-energy ball mill is 400-600rpm, the time is 18-20h, and the ball-to-material ratio is 45-55:

1.

5. The preparation method according to claim 4, characterized in that: The inert gas atmosphere is an argon atmosphere.

6. The preparation method according to claim 4, characterized in that: The high energy ball milling is performed using zirconium oxide balls.

7. The preparation method according to any one of claims 4 to 6, characterized in that: The high-energy ball milling speed is 500 rpm, the time is 20 h, and the ball-to-material ratio is 50:

1.

8. Use of the halide solid electrolyte material according to any one of claims 1 to 3 in the preparation of solid-state batteries.

9. A solid-state battery, characterized in that: The invention comprises the halide solid electrolyte material according to any one of claims 1 to 3.

10. A solid-state battery according to claim 9, characterized in that: The positive electrode and the electrolyte layer thereof both have the halide solid electrolyte material.

Images