A lithium boron sulfide solid electrolyte and its preparation method and an all-solid-state battery
Patent Information
- Application Number
- CN202610969513.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-01
- Publication Date
- 2026-09-22
AI Technical Summary
[0006]本发明提供一种含锂硼硫化物固态电解质及其制备方法与全固态电池，解决现有硫化物固态电解质与锂金属负极反应严重、循环稳定性差的问题，同时实现高离子电导率和高界面稳定性
[0014]本发明具有如下有益效果：本发明提供的含锂硼硫化物固态电解质（本文也简称“电解质”）的制备方法，通过优化机械球磨和高温固相反应的工艺参数，实现了Li9B19S33的高效合成，所合成的电解质在不牺牲室温离子电导率的前提下，利用硼硫阴离子骨架对锂金属负极的潜在稳定性，通过工艺控制改善材料相形成和颗粒均匀性，从而提升了锂金属界面稳定性和全固态电池循环性能，为全固态电池的发展提供了新的材料选择。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of solid-state battery materials technology, and in particular to a lithium boron sulfide solid electrolyte, its preparation method, and an all-solid-state battery. Background Technology
[0002] Lithium-ion batteries are widely used in portable electronic devices, electric vehicles, and energy storage systems. Commercially available liquid lithium-ion batteries typically use flammable organic liquid electrolytes, which pose risks of leakage, combustion, and thermal runaway under conditions of overcharging, short circuits, mechanical damage, or high temperatures. All-solid-state batteries, which replace liquid electrolytes with solid electrolytes, promise to reduce safety risks from the electrolyte system perspective and allow for better matching of lithium metal anodes and high-energy-density cathode materials.
[0003] Currently, the mainstream sulfide electrolytes (such as Li) 10 GeP2S 12 While Li6PS5Cl exhibits extremely high conductivity, its anionic framework is readily reduced and decomposed by lithium metal at low potentials, leading to rapid capacity decay and the generation of interfacial decomposition products. This results in problems such as increased interfacial impedance, uneven lithium deposition / stripping, short circuits, or rapid capacity decay. Therefore, sulfide electrolytes that combine high ionic conductivity with high lithium metal interfacial stability remain a key requirement in this field.
[0004] In recent years, borosilicates have been theoretically found to have higher thermodynamic stability to lithium metal due to their wider electronic band gaps. However, designing and synthesizing specific crystalline borosilicates that simultaneously achieve both high interfacial stability and high room-temperature ionic conductivity remains a technological blind spot hindering the development of this field.
[0005] It should be noted that the information disclosed in the background section above is only for understanding the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention
[0006] This invention provides a lithium boron sulfide solid electrolyte, its preparation method, and an all-solid-state battery, which solves the problems of severe reaction between existing sulfide solid electrolytes and lithium metal anodes and poor cycle stability, while achieving high ionic conductivity and high interface stability.
[0007] The present invention adopts the following technical solution:
[0008] In a first aspect, a method for preparing a lithium boron sulfide solid electrolyte is provided, comprising the following steps:
[0009] (a) Lithium sulfide (Li2S), elemental boron (B), and elemental sulfur (S) are mixed in a molar ratio of Li2S, B, and S of 9:38:57 to obtain a raw material mixture;
[0010] (b) Under an inert atmosphere, the raw material mixture is mechanically ball-milled to obtain precursor powder, wherein the parameters of the mechanical ball milling are: ball-to-material ratio of 20:1 to 50:1 and rotation speed of 350 to 400 r / min;
[0011] (c) Under the protection of an inert atmosphere, the precursor powder undergoes a high-temperature solid-phase reaction. After the reaction is completed, it is cooled to obtain the lithium boron sulfide solid electrolyte. The parameters of the high-temperature solid-phase reaction are: temperature 650-850℃ and reaction time 12h-24h.
[0012] Secondly, a lithium boron sulfide solid electrolyte, prepared by the method described in the first aspect, is provided, having the chemical formula Li9B. 19 S 33 .
[0013] Thirdly, an all-solid-state battery is provided, comprising a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein the solid electrolyte layer comprises the lithium boron sulfide solid electrolyte described in the second aspect.
[0014] The present invention has the following beneficial effects: The preparation method of the lithium boron sulfide solid electrolyte (hereinafter also referred to as "electrolyte") provided by the present invention, through optimizing the process parameters of mechanical ball milling and high-temperature solid-phase reaction, achieves the preparation of Li9B 19 S 33 The efficient synthesis of the electrolyte, without sacrificing room temperature ionic conductivity, utilizes the potential stability of the boron-sulfur anion framework for the lithium metal anode. Through process control, the material phase formation and particle uniformity are improved, thereby enhancing the lithium metal interface stability and the cycle performance of all-solid-state batteries, providing a new material option for the development of all-solid-state batteries. Attached Figure Description
[0015] Figure 1 The image shows the X-ray diffraction (XRD) patterns of the electrolyte LBS and raw materials prepared in Example 5 of this invention.
[0016] Figure 2 The images are scanning electron microscope (SEM) images of the electrolyte LBS prepared in Example 5 of this invention at different magnifications.
[0017] Figure 3 This is an EDS diagram of the electrolyte LBS prepared in Example 5 of the present invention.
[0018] Figure 4 The impedance diagram is shown for the solid electrolyte sheet made of LBS according to Embodiment 5 of the present invention.
[0019] Figure 5This is a curve fitting diagram of the activation energy of the electrolytes in Example 5 and the comparative example of the present invention.
[0020] Figure 6 The graph shows the critical current density test results of the lithium-lithium symmetric battery assembled using the sample LBS from Example 5.
[0021] Figure 7 This is a high current density cycling test diagram of a lithium-lithium symmetric battery assembled using sample LBS from Example 5.
[0022] Figure 8 The graph shows the 1C rate long-cycle performance of the all-solid-state battery with LBS electrolyte prepared in Example 5 of this invention and the all-solid-state battery with commercial LPSC electrolyte.
[0023] Figure 9 The graphs show the high-load cycle performance of the all-solid-state battery with LBS electrolyte prepared in Example 5 of this invention and the all-solid-state battery with commercial LPSC electrolyte. Detailed Implementation
[0024] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope or application of the invention. Unless otherwise specified, the embodiments and features described in this application can be combined with each other. In this document, room temperature refers to 25°C.
[0025] This invention provides a method for preparing a lithium boron sulfide solid electrolyte, comprising the following steps:
[0026] (a) Lithium sulfide (Li2S), elemental boron (B), and elemental sulfur (S) are mixed in a molar ratio of Li2S, B, and S of 9:38:57 to obtain a raw material mixture;
[0027] (b) Under an inert atmosphere, the raw material mixture is mechanically ball-milled to obtain precursor powder, wherein the parameters of the mechanical ball milling are: ball-to-material ratio of 20:1 to 50:1 and rotation speed of 350 to 400 r / min;
[0028] (c) Under the protection of an inert atmosphere, the precursor powder undergoes a high-temperature solid-phase reaction. After the reaction is completed, it is cooled to obtain the lithium boron sulfide solid electrolyte. The parameters of the high-temperature solid-phase reaction are: temperature 650-850℃ and reaction time 12h-24h.
[0029] In some implementations, the ball-to-material ratio in step (b) is 20:1.
[0030] In some implementations, the rotational speed in step (b) is 400 r / min.
[0031] In some embodiments, in step (b), the ball milling time of the mechanical ball mill is 3-4 hours, preferably 3 hours.
[0032] In some embodiments, the temperature of the high-temperature solid-phase reaction in step (c) is 650°C.
[0033] In some embodiments, the cooling rate in step (c) is 5 °C / min.
[0034] In some embodiments, the mechanical ball milling in step (b) uses zirconia grinding balls of a single diameter.
[0035] In some embodiments, step (b) is: under an inert atmosphere, the raw material mixture is mechanically ball-milled to obtain precursor powder, wherein the parameters of the mechanical ball milling are: using zirconia grinding balls with a diameter of 5 mm, a ball-to-material ratio of 20:1, a rotation speed of 400 r / min, and a ball milling time of 3 h; step (c) is: under an inert atmosphere, the precursor powder undergoes a high-temperature solid-phase reaction, and after the reaction is completed, it is cooled and ground for 30 min to obtain the lithium boron sulfide solid electrolyte, wherein the parameters of the high-temperature solid-phase reaction are: a temperature of 650 °C, a cooling rate of 5 °C / min, and a reaction time of 24 h at 650 °C.
[0036] The present invention also provides a lithium boron sulfide solid electrolyte prepared by the aforementioned preparation method, the chemical formula of which is Li9B. 19 S 33 .
[0037] A specific embodiment of the present invention also provides an all-solid-state battery, including a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein the solid electrolyte layer contains the lithium boron sulfide solid electrolyte.
[0038] The following describes specific embodiments of the present invention.
[0039] Examples 1 to 9
[0040] The lithium boron sulfide solid electrolyte Li9B was prepared using the parameters described in Examples 1 to 9. 19 S 33 The preparation parameters and the impedance and ionic conductivity of the resulting electrolyte are shown in Table 1 below:
[0041] Table 1
[0042] 1 mix 50:1 350 3 650 5 66.8 1.33 2 mix 50:1 350 3 850 5 58.4 1.53 3 mix 50:1 400 3 650 5 21.6 4.13 4 pure 50:1 400 3 650 5 21.3 4.19 5 pure 20:1 400 3 650 5 16.5 6.19 6 pure 20:1 350 3 650 5 20.1 4.70 7 pure 20:1 350 4 650 5 17.8 5.01 8 mix 30:1 400 4 650 5 63.1 1.41 9 mix 30:1 400 3 650 5 60.8 1.47
[0043] In Table 1 above, "pure" in grinding balls indicates the use of 5 mm zirconia grinding balls (pure bead abrasive), and "mixed" indicates the use of zirconia grinding balls with diameters of 2 mm, 5 mm, and 8 mm in a mass ratio of 2:3:5 (mixed bead abrasive).
[0044] Taking Example 5 as an example, the preparation method of the lithium boron sulfide solid electrolyte includes the following steps:
[0045] (a) Lithium sulfide (Li2S), elemental boron (B), and elemental sulfur (S) are mixed in a molar ratio of Li2S, B, and S of 9:38:57 to obtain a raw material mixture;
[0046] (b) Under the protection of argon atmosphere, the raw material mixture is mechanically ball-milled to obtain precursor powder, wherein the parameters of the mechanical ball milling are: using zirconia grinding balls with a diameter of 5 mm, ball-to-material ratio (i.e., mass ratio of zirconia grinding balls to raw material mixture) of 20:1, rotation speed of 400 r / min, and ball milling time of 3 h.
[0047] (c) Under an argon atmosphere, the precursor powder was transferred to a graphite crucible, sealed with tin foil, and then placed in a muffle furnace for a high-temperature solid-state reaction. After the reaction was completed, the mixture was cooled and then ground in a mortar for 30 minutes to obtain the lithium boron sulfide solid electrolyte with the chemical formula Li9B. 19 S 33 (referred to as LBS), wherein the parameters of the high-temperature solid-phase reaction are: temperature 650℃, cooling rate 5℃ / min, and reaction time at 650℃ for 24h.
[0048] Steps (b) and (c) above were performed in a glove box filled with an argon atmosphere, with oxygen and water content both below 0.01 ppm.
[0049] The other embodiments differ from Embodiment 5 in that the parameters in steps (b) and (c) are different (see Table 1), otherwise they are the same as Embodiment 5.
[0050] As shown in Table 1 above, the data comparison between Examples 1 and 2 indicates that temperature changes have a relatively small impact on the ionic conductivity of the electrolyte; therefore, the preferred temperature is 650 °C. The data comparison between Examples 3 and 4 shows that using mixed bead abrasives in a high-energy ball mill can refine the grains, but it also introduces more grain boundaries, leading to a decrease in ionic conductivity; therefore, pure bead abrasives are preferred. The data comparison between Examples 4 and 5 shows that different ball-to-material ratios have a significant impact on the impedance of the synthesized electrolyte; a ball-to-material ratio of 20:1 is preferred. The data comparison between Examples 5 and 6 shows that the electrolyte synthesized at a rotation speed of 400 r / min has higher ionic conductivity and lower impedance. The data comparison between Examples 6 and 7 shows that the rotation speed at... The electrolyte synthesized at 350 r / min for 4 h exhibits lower impedance and higher ionic conductivity. A comparison of data from Examples 8 and 9 shows that the electrolyte synthesized at 400 r / min for 3 h exhibits lower impedance and higher ionic conductivity. Combining the preceding information and the comparison of data from Examples 5 and 7, the ball milling parameters of 400 r / min + 3 h are superior to 350 r / min + 4 h. Therefore, a ball milling speed of 400 r / min and a ball milling time of 3 h are preferred. In summary, the optimal preparation route uses the parameters from Example 5.
[0051] The preparation of solid electrolyte sheets and the assembly of batteries using the electrolyte prepared in Example 5 include the following steps:
[0052] 1. Preparation of solid electrolyte sheets
[0053] Weigh 100 mg of the LBS prepared in Example 5 and place it in the ceramic inner liner of a CL-01 mold battery (with an inner liner pore size of 10 mm), ensuring that the powder is uniform, flat, and free of obvious lumps. Use two steel columns as pressure heads and cold press for 5 minutes under a pressure of 3 tons to form a dense, uniformly thick (approximately 600 μm) solid electrolyte sheet. Remove this pressed solid electrolyte sheet from the mold for later use.
[0054] 2. Assembly of lithium-ion symmetric batteries
[0055] The solid electrolyte sheet prepared in step 1 was placed into the CL-01 mold battery. A 6 mm diameter lithium metal sheet was placed as an electrode on each side of the solid electrolyte sheet, and copper foil was used as a current collector. The upper and lower steel pillars were then placed on top, and an external pressure of 1 ton was applied to encapsulate the battery to obtain a lithium-lithium symmetric battery (Li | LBS | Li) for testing.
[0056] 3. Assembly of all-solid-state batteries
[0057] Cathode slurry preparation: The lithium niobate-coated ternary cathode material (LNO@NCM811), the solid electrolyte material (LBS) prepared in Example 5, and conductive carbon black were ground and mixed uniformly in a mortar for 30 min at a mass ratio of 70:25:5.
[0058] Positive electrode preparation: The above positive electrode slurry is placed in a mold and pressed into shape under appropriate pressure.
[0059] Battery assembly: The lithium metal negative electrode, the solid electrolyte sheet prepared in step 1, and the positive electrode sheet prepared above are sequentially placed into the battery mold for assembly. Appropriate pressure is applied, and the battery is encapsulated to obtain an all-solid-state battery (NCM811 | LBS | Li).
[0060] As a comparative example, the same method was used to compare commercially available LGPS (Li 10 GeP2S 12 Solid electrolyte sheets were prepared using electrolyte (purchased from Ganfeng Lithium) and commercial LPSC (Li6PS5Cl) electrolyte (purchased from Ganfeng Lithium); all-solid-state batteries (NCM811 | LPSC | Li) were assembled using commercial LPSC.
[0061] The following tests were performed on Example 5 and the comparative example described above:
[0062] The samples from Example 5 were characterized by X-ray diffraction (XRD) using a Bruker D8 Advance diffractometer with Cu Kα rays (λ = 0.15406 nm) as the radiation source. The operating conditions were a tube voltage of 45 kV and a tube current of 40 mA. The scan rate was 10° / min within the 2θ range of 10°–90°. The XRD patterns of the samples and raw materials from Example 5 are shown below. Figure 1 As shown, the results indicate that the peaks of the raw material disappeared and new peak positions were formed. Three strong peaks appeared at 34°, 48°, and 61°, which are the peak positions of the target product LBS, meaning that a new borosilicate was synthesized.
[0063] The morphology of the electrolyte LBS in Example 5 was characterized by field emission scanning electron microscopy (HITACHI S-4800, SU8010) and equipped with an energy dispersive spectroscopy (EDS, IXRF SYSTEM, 550i). Figure 2 As shown in the scanning electron micrograph, the synthesized sample materials all exhibit irregular granular shapes, clustered together. This is due to the softness of the sulfide material, causing deformation during the grinding process. Figure 3 As shown in the EDS elemental distribution diagram of the LBS sample in Example 5, the Li, B, and S elements are evenly distributed in the LBS particles, and each element is successfully introduced and well dispersed.
[0064] To further confirm the elemental composition and proportions in the electrolyte synthesized in Example 5, inductively coupled plasma atomic emission spectrometry (ICP) was performed. The cation ratio, Li / B, was set as the confirmation standard, and the data are shown in Table 2 below. Since ICP testing requires complete dissolution of the electrolyte powder in a dilute nitric acid / hydrochloric acid mixture, this method tends to test the cation ratio. Furthermore, the inability to isolate water and oxygen during the test results in sulfur volatilization into the air, leading to issues with the S ratio. This paper estimates the S value through valence state fitting, using the Li / B value as a reference. It can be seen that the Li / B ratio of the synthesized sample is approximately the theoretical Li / B ratio, indicating that the valence state conforms to the theory. Therefore, the synthesized sample is considered to be consistent with the prediction.
[0065] Table 2 Synthesized Li9B 19 S 33 The proportion of B and Li elements
[0066] Li 0.32 9 B 0.62 19 Li / B 0.50 0.47
[0067] Electrochemical impedance spectroscopy (EIS) measurements were performed on a multichannel electrochemical workstation (VMP3, Biologic), with a frequency range of 7 MHz to 100 mHz. Figure 4 As shown, the total impedance of the solid electrolyte sheet made of LBS in Example 5 is approximately 16.5 Ω, corresponding to an ionic conductivity of 6.19 mS·cm at room temperature. -1 .like Figure 5 As shown, the ionic conductivity at various temperatures can be obtained by testing the total impedance of the electrolytes in Example 5 and the comparative example at different temperatures. The activation energies of LPSC, LGPS, and LBS can be calculated by performing a linear fit using the Arrhenius equation and obtaining the slope. The activation energies of commercially available LGPS and LPSC are Ea = 0.23 eV and Ea = 0.30 eV, respectively, while the LBS electrolyte synthesized in Example 5 exhibits an extremely low activation energy (Ea = 0.14 eV). This means that the electrolyte has a lower migration energy barrier during ion migration, requiring less energy to overcome during transport, making ion transport easier. This corresponds to the high ionic conductivity of the LBS electrolyte.
[0068] The electrochemical performance of the symmetric cells was tested using a multi-channel cell testing system (LAND CT 2001 A, China), and stepwise increasing constant current deposition / stripping tests were performed to determine the critical current density (CCD). Each increment of current density corresponds to an areal capacity of 0.05 mAh·cm³. -2 (Step rate 0.177 mA·cm) -2Continue depositing / stripping until the overpotential rises sharply above the cutoff voltage (5 V) or a short circuit occurs. For example... Figure 6 As shown, the lithium-lithium symmetric battery assembled using the sample LBS from Example 5 exhibits excellent current tolerance, with a final measured critical current density (CCD) as high as 8.40 mA·cm⁻¹. -2 The overpotential remained stable (< 100 mV) throughout the testing range. This indicates that the LBS electrolyte can handle larger currents when matched with a lithium metal anode, exhibiting excellent interfacial compatibility and structural stability. Figure 7 As shown, at 5 mA·cm -2 The current density and 5 mAh·cm -2 Under the deposition amount, a long-cycle test of lithium-lithium symmetric battery was conducted. The LBS electrolyte was stably cycled for 1200 h under these conditions, with the overpotential remaining at a relatively low level (< 50 mV) and no signs of short circuit or open circuit.
[0069] As a comparison, the all-solid-state battery assembled with the commercial LPSC electrolyte and the LBS electrolyte of Example 5 was subjected to electrochemical performance testing on a multi-channel battery testing system, with a voltage range of 2.7-4.3 V (relative to Li). + / Li). For example Figure 8 As shown ( Figure 8 In the middle, the areal capacity of the positive electrode active material is 8.92 mg·cm³. -2 The capacity of commercially available all-solid-state batteries with LPSC electrolytes continuously decreases during cycling. After 2222 cycles, the NCM811|LPSC|Li all-solid-state battery experiences a short circuit, at which point its capacity retention is only 66.7% of the initial capacity. In contrast, the NCM811|LBS|Li all-solid-state battery maintains 92% of its capacity after 4900 stable cycles under the same load and rate, demonstrating excellent cycle stability. Figure 9 As shown, the surface loading of the positive electrode active material is 17.82 mg·cm⁻¹. -2 Under high load, the all-solid-state battery NCM811|LPSC|Li retained only 25% of its capacity after 1400 cycles, while the all-solid-state battery NCM811|LBS|Li retained 96% of its capacity after 1400 cycles under the same conditions, with a capacity of 105 mAh·g. −1 It also exhibits excellent cycle stability under high loads.
[0070] As can be seen from the comparison of Example 5 and the comparative example above, the LBS solid electrolyte has the following properties:
[0071] (1) The impedance at room temperature (25℃) is approximately 16.5 Ω, corresponding to a lithium-ion conductivity of 6.19 mS·cm at room temperature. -1 .
[0072] (2) Based on the temperature impedance test and the fitting of the Arrhenius formula, the lithium-ion migration activation energy of LBS is 0.14 eV, which is lower than 0.23 eV of commercial LGPS and 0.30 eV of commercial LPSC.
[0073] (3) In the Li|LBS|Li symmetric cell, the critical current density of LBS reaches 8.40 mA·cm. -2 The polarization voltage remained stable during the test.
[0074] (4) At 5 mA·cm -2 and 5 mAh·cm -2 Under these conditions, the Li|LBS|Li symmetric cell can operate stably for 1200 hours with a polarization voltage below 50 mV and no signs of short circuit or open circuit.
[0075] (5) When matched with LNO@NCM811 high-nickel ternary cathode, the all-solid-state battery can be stably cycled for 4900 cycles at 1C rate with a capacity retention rate of 92%.
[0076] (6) At 17.82 mg·cm -2 Under high positive electrode load, the all-solid-state battery retains 96% of its capacity after 1400 cycles, with a capacity of approximately 105 mAh g⁻¹. -1 .
[0077] In summary, the lithium boron sulfide solid electrolyte of this invention exhibits significantly superior performance compared to existing commercially available sulfide materials, and the synthesized Li9B... 19 S 33 Boron sulfide solid electrolytes have high ionic conductivity (6.19 mS·cm). -1 This significantly improves the stability of the matched lithium metal anode (critical current density > 8.40 mA cm⁻¹). −2 The ternary cathode exhibits ultra-long cycle stability (stable cycle of 4900 cycles with capacity retention ≥92%), which improves ionic conductivity and overcomes the core defect of poor cycle stability caused by the severe reaction between existing sulfide solid electrolytes and lithium metal anodes.
[0078] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope of protection of the patent application.
Claims
1. A method for preparing a lithium boron sulfide solid electrolyte, characterized in that, Includes the following steps: (a) Lithium sulfide (Li2S), elemental boron (B), and elemental sulfur (S) are mixed in a molar ratio of Li2S, B, and S of 9:38:57 to obtain a raw material mixture; (b) Under an inert atmosphere, the raw material mixture is mechanically ball-milled to obtain precursor powder, wherein the parameters of the mechanical ball milling are: ball-to-material ratio of 20:1 to 50:1 and rotation speed of 350 to 400 r / min; (c) Under the protection of an inert atmosphere, the precursor powder undergoes a high-temperature solid-phase reaction. After the reaction is completed, it is cooled to obtain the lithium boron sulfide solid electrolyte. The parameters of the high-temperature solid-phase reaction are: temperature 650-850℃ and reaction time 12h-24h.
2. The preparation method according to claim 1, characterized in that, In step (b), the ball-to-material ratio is 20:
1.
3. The preparation method according to claim 1, characterized in that, In step (b), the rotational speed is 400 r / min.
4. The preparation method according to claim 1, characterized in that, In step (b), the ball milling time of the mechanical ball mill is 3-4 hours, preferably 3 hours.
5. The preparation method according to claim 1, characterized in that, In step (c), the temperature of the high-temperature solid-phase reaction is 650°C.
6. The preparation method according to claim 1, characterized in that, In step (c), the cooling rate is 5 °C / min.
7. The preparation method according to claim 1, characterized in that, In step (b), the mechanical ball milling uses zirconia grinding balls of a single diameter.
8. The preparation method according to claim 1, characterized in that, Step (b) is as follows: Under an inert atmosphere, the raw material mixture is mechanically ball-milled to obtain precursor powder. The parameters of the mechanical ball milling are: using zirconia grinding balls with a diameter of 5 mm, a ball-to-material ratio of 20:1, a rotation speed of 400 r / min, and a ball milling time of 3 h. Step (c) is as follows: Under the protection of an inert atmosphere, the precursor powder undergoes a high-temperature solid-phase reaction. After the reaction is completed, it is cooled and ground for 30 minutes to obtain the lithium boron sulfide solid electrolyte. The parameters of the high-temperature solid-phase reaction are: temperature 650℃, cooling rate 5℃ / min, and reaction time at 650℃ for 24 hours.
9. A lithium boron sulfide solid electrolyte prepared by the preparation method according to any one of claims 1 to 8, characterized in that, Its chemical formula is Li9B 19 S 33 .
10. An all-solid-state battery, comprising a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive and negative electrodes, characterized in that, The solid electrolyte layer comprises the lithium boron sulfide solid electrolyte as described in claim 9.