SbBr co-doped argyrodite type solid electrolyte and preparation method thereof

Abstract

The invention discloses a SbBr co-doped argyrodite type solid electrolyte and a preparation method thereof.The preparation method comprises the steps that Li2S, LiCl, P2S5 and SbBr3 are weighed according to the stoichiometric ratio and then subjected to ball milling treatment, and mixed powder is obtained; the mixed powder obtained in the step S1 is subjected to compression molding and placed in a muffle furnace to be heated and calcined, and a solid-phase reaction is conducted; and after the reaction is finished, naturally cooling to room temperature, and grinding to obtain the SbBr co-doped argyrodite type solid electrolyte. According to the preparation process of the argyrodite type solid electrolyte, a traditional solid-phase sintering process is adopted, the synthesis process is simple, and the repeatability is high. The ionic conductivity of the argyrodite type solid electrolyte prepared by the process can reach 10.4 mScm <-1 > at room temperature. The argyrodite type solid electrolyte prepared by the invention has high ionic conductivity and excellent air stability, and meets the requirements of industrial large-scale production. When the solid-state electrolyte provided by the invention is assembled into an all-solid-state battery, the cycle life of the all-solid-state battery can be remarkably prolonged due to good compatibility with lithium metal.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of solid-state batteries, in particular to a SbBr co-doped argyrodite solid-state electrolyte and a preparation method thereof. BACKGROUND

[0002] Liquid lithium-ion batteries have been deeply integrated into various dimensions of energy power and daily life due to their high energy density, wide working temperature range and long cycle life. However, with the rapid development of the electric vehicle industry and the continuous rise in demand for portable electronic devices, traditional lithium-ion batteries (with organic electrolyte as the core component) have been unable to meet the urgent needs of high safety and higher energy density for social development. In comparison, all-solid-state lithium batteries use solid-state electrolytes to fundamentally avoid the safety hazards of liquid electrolyte leakage and explosion, and have the potential to break through the upper limit of energy density, becoming a research hotspot in the current energy storage field. Among them, sulfide solid-state electrolytes are considered one of the most promising solid-state electrolyte systems due to their room-temperature ionic conductivity exceeding 10 -3 Scm -1 and excellent ductility.

[0003] Despite the significant advantages of sulfide solid-state electrolytes, their commercialization still faces two major obstacles. First, the material is prone to degradation in humid environments, and even exposure to low-humidity air can release toxic H2S gas, severely limiting its large-scale production and practical application. Second, the interface compatibility between sulfide solid-state electrolytes and lithium anodes is insufficient, and when they come into contact, side reactions easily occur, forming an unstable interface layer and inducing lithium dendrite growth, leading to shortened battery cycle life and increased safety risks. Therefore, how to improve the (electro)chemical stability of sulfide solid-state electrolytes while maintaining high ionic conductivity and building a high-performance all-solid-state battery system has become a technical problem that needs to be solved urgently. SUMMARY

[0004] To solve the above problems, the present application aims to provide a SbBr co-doped argyrodite solid-state electrolyte and a preparation method thereof.

[0005] To achieve the technical purpose, the present application provides a SbBr co-doped argyrodite solid-state electrolyte, which has a chemical formula of Li 5.5-x P 1-x Sb x S 4.5-3x Br 3x Cl 1.5 , wherein 0

[0006] A preparation method for preparing a SbBr co-doped argyrodite solid-state electrolyte, comprising the following specific steps:

[0007] S1, take Li2S, LiCl, P2S5, SbBr3 in stoichiometric ratio, then perform ball milling treatment to obtain a mixed powder;

[0008] S2, press the mixed powder obtained in step S1 into a shape, and place it in a muffle furnace to perform calcination and solid phase reaction;

[0009] S3, after the reaction is completed, naturally cool to room temperature, and grind to obtain a SbBr co-doped argyrodite solid-state electrolyte.

[0010] Preferably, the steps S1, S2 and S3 are all performed in an argon atmosphere.

[0011] Preferably, in step S2, the ball milling is two-stage ball milling, and the ball milling is performed in an oxygen-free environment, and the process conditions include: the rotation speed of the first-stage ball milling is 400-600 rpm, and the time is 1-3 h; the rotation speed of the second-stage ball milling is 700-900 rpm, and the time is 10-20 h.

[0012] Preferably, in step S2, the pressure used for the pressing is 3-5 t, and the pressure maintaining time is greater than 3 min.

[0013] Preferably, in step S2, the mixed powder is pressed into a sheet shape, and the thickness of the sheet shape is 10-30 mm.

[0014] Preferably, in step S2, the sintering temperature of the crystallization sintering is 500-600 ℃, the heating rate is 1-10 ℃ / min, and the sintering time is 6-10 h.

[0015] Preferably, in step S3, the grinding time is greater than 15 min, and the particle size of the sulfide solid-state electrolyte after screening is 5-30 μm.

[0016] An application of a SbBr co-doped argyrodite solid-state electrolyte in a full solid-state battery.

[0017] Compared with the prior art, the present application has the following beneficial technical effects:

[0018] (1) The preparation process of the argyrodite solid-state electrolyte provided by the present application adopts a traditional solid phase sintering process, and the synthesis process is simple and has high repeatability. The Li 5.5 PS 4.5 Cl 1.5 The ionic conductivity at room temperature can reach 10.4 mScm -1 .

[0019] (2) The Sb / Br co-doped argyrodite solid-state electrolyte prepared by the present application has high ionic conductivity and excellent air stability, and meets the needs of industrial large-scale production.

[0020] (3) When the solid electrolyte provided by the present invention is assembled into an all-solid-state battery, its good compatibility with lithium metal can significantly extend the cycle life of the all-solid-state battery. Attached Figure Description

[0021] Figure 1 Impedance diagrams for Comparative Example 1 and Example 1 of the present invention;

[0022] Figure 2 The above are air stability test diagrams for Comparative Example 1 and Example 1 of the present invention;

[0023] Figure 3 The X-ray diffraction (XRD) images are of Comparative Example 1 and Examples 1, 2, 3, 6, and 7 of the present invention.

[0024] Figure 4 This is a cycle stability graph of Comparative Example 1 of the present invention in an all-solid-state battery for the 1st, 10th, 50th, and 100th cycles.

[0025] Figure 5 This is a cycle stability graph of Embodiment 1 of the present invention in an all-solid-state battery for the 1st, 10th, 50th, and 100th cycles. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0027] like Figures 1-5 As shown, a specific embodiment of the present invention is a method for preparing an SbBr co-doped silver-germanium sulfide-type solid electrolyte. The SbBr co-doped silver-germanium sulfide-type solid electrolyte has the general chemical formula Li. 5.5-x P 1-x Sb x S 4.5- 3x Br 3x Cl 1.5 Where 0 < x ≤ 0.1. The specific steps are as follows:

[0028] S1. Weigh Li2S, LiCl, P2S5, and SbBr3 according to the stoichiometric ratio, and then ball mill them to obtain a mixed powder.

[0029] S2, the mixed powder obtained in step S1 is press-formed and placed in a muffle furnace for heating and calcination to perform a solid phase reaction; the ball milling is two-stage ball milling, and the ball milling is performed in an oxygen-free environment, and the process conditions include: the rotation speed of the first-stage ball milling is 400-600 rpm, and the time is 1-3 h; the rotation speed of the second-stage ball milling is 700-900 rpm, and the time is 10-20 h. The pressure used for press-forming is 3-5 t, and the pressure maintaining time is greater than 3 min. The mixed powder is press-formed into a sheet shape, and the thickness of the sheet shape is 10-30 mm. The sintering temperature of the crystallization sintering is 500-600℃, the heating rate is 1-10℃ / min, and the sintering time is 6-10 h.

[0030] S3, after the reaction is completed, natural cooling to room temperature is performed, and grinding is performed to obtain an SbBr co-doped argyrodite solid-state electrolyte. The grinding time is greater than 15 min, and the particle size of the sulfide solid-state electrolyte after screening is 5-30 μm. The steps S1, S2 and S3 are all performed in an argon atmosphere.

[0031] An application of an SbBr co-doped argyrodite solid-state electrolyte in a full solid-state battery.

[0032] The electrolyte material has excellent ionic conductivity, and simultaneously has excellent air stability and lithium compatibility, and the chemical general formula is Li 5.5-x P 1-x Sb x S 4.5-3x Br 3x Cl 1.5 , and 0 3+ substitutes P 5+ , not only widens the lithium diffusion channel in the structure, but also effectively inhibits the reaction of the material and oxygen in the ambient air; the introduced Br - on the one hand can positively regulate the lithium ion migration dynamics, and on the other hand can significantly improve the lithium stability of the material. Experiments show that the argyrodite solid-state electrolyte exhibits excellent ion transport performance, outstanding air stability and good lithium interface compatibility. In addition, the preparation method is simple and easy to operate, which lays a solid foundation for large-scale industrial production and application.

[0033] Example 1

[0034] S1: Li2S, LiCl, P2S5 and SbBr3 are mixed according to a molar ratio of 1.97:1.5:0.47:0.06, placed in a sealed zirconia ball mill tank filled with argon, and pre-mixed by ball milling at a speed of 500 rpm for 2 h, and then ball milling is performed at a speed of 800 rpm for 15 h to obtain an argyrodite solid-state electrolyte precursor powder.

[0035] S2: The precursor powder was pressed into a sheet-shaped solid with a diameter of 10 mm and a thickness of 15 mm under a pressure of 3 t for 3 min, and then was placed in a corundum crucible and heated to 500°C at a rate of 2°C / min, and was kept at 500°C for 8 h, and was naturally cooled to obtain the product argyrodite solid-state electrolyte Li 5.5-x P 1-x Sb x S 4.5-3x Br 3x Cl 1.5 .

[0036] In this embodiment, the chemical formula of the product is Li 5.44 P 0.94 Sb 0.06 S 4.32 Br 0.18 Cl 1.5 .

[0037] Comparative Example 1

[0038] S1: Li2S, LiCl, P2S5 were mixed in a molar ratio of 2:1.5:0.5, and were placed in a sealed zirconia ball mill tank filled with argon, and were pre-mixed by ball milling at a speed of 500 rpm for 3 h, and then were ball-milled at a speed of 500 rpm for 20 h to obtain an argyrodite solid-state electrolyte precursor powder.

[0039] S2: The precursor powder was pressed into a sheet-shaped solid with a diameter of 10 mm and a thickness of 15 mm under a pressure of 5 t for 2 min, and then was placed in a corundum crucible and heated to 600°C at a rate of 5°C / min, and was kept at 600°C for 6 h, and was naturally cooled to obtain the product Li 5.5 PS 4.5 Cl 1.5 .

[0040] To simplify the description, the preparation processes and product-related parameters of Examples 2-7 are listed in the following table, and the parameters not listed are the same as those of Example 1.

[0041] Example No. x Secondary ball milling speed and time Solid state reaction temperature and time Chemical formula of product Ionic conductivity (mS / cm) Example 2 0.02 800 rpm, 20 h 550℃,8h Li 5.48 P 0.98 Sb 0.02 S 4.44 Br 0.06 Cl 1.5 ]]> 10.6 Example 3 0.04 900 rpm, 15 h 500℃,10h Li 5.46 P 0.96 Sb 0.04 S 4.38 Br 0.12 Cl 1.5 ]]> 11.3 Example 4 0.06 700 rpm, 20 h 500℃,8h Li 5.44 P 0.94 Sb 0.06 S 4.32 Br 0.18 Cl 1.5 ]]> 10.6 Example 5 0.06 900 rpm, 10 h 600℃,6h Li 5.44 P 0.94 Sb 0.06 S 4.32 Br 0.18 Cl 1.5 ]]> 11.2 Example 6 0.08 900 rpm, 10 h 550℃,7h Li 5.42 P 0.92 Sb 0.08 S 4.26 Br 0.24 Cl 1.5 ]]> 9.9 Example 7 0.10 900 rpm, 15 h 500℃,10h Li 5.4 P 0.90 Sb 0.1 S 4.2 Br 0.3 Cl 1.5 ]]> 6.5

[0042] Conductivity test: The ionic conductivity of the solid-state electrolyte was obtained by analyzing the electrochemical impedance spectrum (EIS). Comparative Example 1 and Examples 1-7 were respectively pressed into a circular sheet with a diameter of 10 mm and a thickness of about 1.57 mm under a pressure of 3.5 t, and the two sides were respectively blocked with stainless steel current collectors, and then were assembled in a polyether ether ketone (PEEK) mold (diameter: 10 mm) and were tested for ionic conductivity under an external pressure of about 0.5 t. The test equipment was a MULTI-AUTOLAB-M204 type electrochemical workstation, the test frequency range was 1 Hz-1 MHz, and the excitation amplitude was 10 mV. The test results are shown in Table 2.Figure 1 and Figure 2 .

[0043] As Figure 1 can be seen, the ionic conductivity of the Sb / Br doped argyrodite solid state electrolyte prepared in Example 1 is 11.8 mScm -1 , which is greater than that of Comparative Example 1. This shows that Sb with a large atomic radius can expand the lithium diffusion channel in the structure, and the doped Br element introduces new lithium ion diffusion channels, together improving the ionic conductivity of the electrolyte.

[0044] Air stability test

[0045] The test conditions are: exposing the electrolyte powder to a room temperature, 50% air humidity atmosphere, and testing the content of hydrogen sulfide released by the electrolyte with a hydrogen sulfide sensor (0-100 ppm), as shown in Figure 2 , are the air stability test results of the electrolytes prepared in Example 1 and Comparative Example 1.

[0046] The volume concentration of H2S gas generated by the undoped argyrodite solid state electrolyte (Comparative Example 1) and Example 1 in a closed environment for 60 min is 5.1 and 1.5 cm 3 g -1 , respectively. As can be seen, after introducing the soft acid Sb 3+ to replace P 5+ , the strong combination between Sb and S can inhibit the reaction with oxygen (hard base) in the ambient air, greatly improving the air stability of the argyrodite solid state electrolyte.

[0047] X-ray diffraction analysis, as shown in Figure 3 , are the X-ray diffraction (XRD) patterns of the electrolytes prepared in Comparative Example 1 and Examples 1, 2, 3, 6, and 7.

[0048] As Figure 3 can be seen, the electrolyte with low concentration of SbBr3doping and the undoped electrolyte spectrum Figure 1 are essentially the same, and no other impurity peaks appear, indicating that Sn and N are successfully doped into the original structure and do not destroy the original lattice structure. When the concentration is too high (Examples 6 and 7), many impurity peaks appear, indicating that too high a proportion of SbBr3has already failed to enter the lattice to replace the corresponding elements to form a solid solution.

[0049] Battery assembly and performance test, the argyrodite solid state electrolytes prepared in Comparative Example 1 and Example 1 are assembled into batteries, and their electrochemical performance is tested. The specific steps are: Li(Ni 0.80 Co 0.10 Mn 0.10O2, the sulfide-germanium ore-type solid electrolyte and carbon nanofiber (VGCF) prepared in the above comparative example and embodiment were mixed uniformly at a mass ratio of 70:27:3 to obtain composite positive electrode powder; graphite and the solid electrolyte prepared in the above comparative example and embodiment were mixed uniformly at a mass ratio of 6:4 to prepare composite negative electrode powder. The positive electrode mixed powder, electrolyte and negative electrode mixed powder were sequentially and uniformly sprinkled into a self-made mold, fully compacted, and stainless steel current collectors were placed on both sides. Then, an axial pressure of 3.5t was applied to densify the electrolyte layer and ensure that the layers were in close contact. Finally, the battery was subjected to constant current charge and discharge test at a stacking pressure of 0.5t, with a measurement range of 2.8V to 4.3V, a charge and discharge rate of 0.2C, and a temperature of 35℃.

[0050] like Figure 4 and Figure 5 As shown, the results indicate that the introduction of SbBr3 significantly improves the cycling stability and capacity performance of the full cell.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any minor modifications, equivalent substitutions, and improvements made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A SbBr co-doped silver-germanium sulfide-type solid electrolyte, characterized in that, Its general chemical formula is Li 5.5-x P 1- x Sb x S 4.5-3x Br 3x Cl 1.5 , where 0 < x ≤ 0.

1.

2. A preparation method, characterized in that, The specific steps for preparing the SbBr co-doped silver-germanium sulfide solid electrolyte of claim 1 are as follows: S1. Weigh Li2S, LiCl, P2S5, and SbBr3 according to the stoichiometric ratio, and then ball mill them to obtain a mixed powder. S2. Press the mixed powder obtained in step S1 into a shape, place it in a muffle furnace and heat it to calcine for solid-phase reaction; S3. After the reaction is complete, the mixture is naturally cooled to room temperature and then ground to obtain an SbBr co-doped silver-germanium sulfide-type solid electrolyte.

3. The preparation method according to claim 2, characterized in that, Steps S1, S2, and S3 are all performed under an argon atmosphere.

4. The preparation method according to claim 2, characterized in that, In step S2, the ball milling is a two-stage ball milling process in which oxygen is isolated. The process conditions include: the rotation speed of the first stage ball milling is 400-600 rpm and the time is 1-3 hours; the rotation speed of the second stage ball milling is 700-900 rpm and the time is 10-20 hours.

5. The preparation method according to claim 2, characterized in that, In step S2, the pressure used for pressing and molding is 3-5t, and the holding time is greater than 3min.

6. The preparation method according to claim 2, characterized in that, In step S2, the mixed powder is pressed into sheets with a thickness of 10-30 mm.

7. The preparation method according to claim 2, characterized in that, In step S2, the sintering temperature of the crystallization sintering is 500-600℃, the heating rate is 1-10℃ / min, and the sintering time is 6-10h.

8. The preparation method according to claim 2, characterized in that, In step S3, the grinding time is greater than 15 min, and the particle size of the sulfide solid electrolyte after sieving is 5-30 μm.

9. The application of the SbBr co-doped silver-germanium sulfide solid electrolyte as described in claim 1 in an all-solid-state battery.

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