Core-shell structure halide solid electrolyte, precursor and preparation method thereof

Abstract

The invention discloses a core-shell structure halide solid electrolyte, a precursor thereof and a preparation method, and relates to the technical field of solid electrolytes. The general chemical formula of the solid electrolyte is Li < 2 + a > MCl < 6-x > Br < x >, M is one of Zr, Hf, Ta, Sn or Ce, and a is greater than or equal to 0 and less than or equal to 2, 0 lt; xlt; 6; the inner core of the electrolyte is rich in Cl <->, the shell of the electrolyte is rich in Br <->, and the Cl / Br ratio is in continuous gradient change. According to the structure, the excellent interface contact and ion transmission capability of the Br phase of the shell and the excellent high-voltage oxidation resistance of the Cl phase of the inner core are integrated, so that the long-term compatibility with a high-voltage positive electrode and the effective inhibition on the growth of lithium dendrites are realized. An innovative LDH template method is adopted, topological transformation to a target electrolyte is achieved, a low-temperature, energy-saving and efficient synthesis path is provided, the hydrolysis problem of halide in synthesis is effectively solved, and the purity and electrochemical performance of a product are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte technology, and more specifically, to a core-shell structured halide solid electrolyte, its precursor, and its preparation method. Background Technology

[0002] Halide solid-state electrolytes, as key materials for next-generation all-solid-state batteries, have attracted much attention due to their combined advantages, including high ionic conductivity, wide electrochemical window, and good processability. Compared to oxide and sulfide systems, typical halide electrolyte materials possess unique lithium-ion transport channels in their structure. Their high ionic conductivity mainly stems from the strong electronegativity of halide anions, which significantly reduces the migration barrier of lithium ions, resulting in a conductivity increase of an order of magnitude compared to traditional oxide electrolytes. Simultaneously, these materials exhibit high oxidation resistance potentials, enabling direct matching with high-voltage cathode materials and effectively simplifying the modification process of the cathode interface. Furthermore, the low melting point of halide materials facilitates densification sintering at lower temperatures, thereby significantly reducing the energy consumption and cost of solid-state battery manufacturing.

[0003] However, the mainstream synthesis methods for these materials still face significant technical bottlenecks. Traditional high-temperature solid-state methods require prolonged heat treatment at high temperatures, leading to the melting of some components and abnormal grain growth, resulting in coarsening of the final product grains and a severe increase in interfacial contact resistance. Simultaneously, the high-temperature process easily causes the volatilization of halogen components, causing the product to deviate from the ideal stoichiometry, thereby reducing the lithium-ion transference number and bulk conductivity of the material. This method also struggles to construct fine microstructures within the material to enhance its mechanical or electrochemical properties. To improve the material's microstructure, novel synthesis strategies such as solution template methods have been proposed, which can, to some extent, achieve the design of heterostructures such as core-shell structures. However, these methods easily introduce carbon residues during template removal, leading to increased electronic conductivity and increasing the risk of short circuits within the battery. Furthermore, the uneven distribution of dopant ions within the structure results in ionic conductivity far lower than theoretically expected, limiting the full realization of the material's performance.

[0004] The aforementioned synthetic bottlenecks further restrict the application of halogen composition control and structural engineering in optimizing material properties. In the preparation of halogen solid solutions, traditional processes struggle to achieve uniform doping at the atomic scale, leading to localized compositional fluctuations that affect the continuity of lithium-ion migration pathways and cause increased activation energy. Regarding core-shell structure construction, existing methods lack sufficient precision in controlling shell thickness and tend to form wide interdiffusion regions at the interface, disrupting the ideal chemical potential distribution and causing a significant increase in interfacial impedance. Therefore, developing novel synthetic strategies capable of precise compositional control and structural regulation has become crucial for promoting the practical application of halide solid electrolytes.

[0005] In view of this, the present invention is proposed. SUMMARY OF THE INVENTION

[0006] The object of the present invention is to provide a core-shell structured halide solid electrolyte, its precursor and preparation method, and use the layered double hydroxide (LDH) templating method to controllably prepare a non-rare-earth double-anion halide solid electrolyte Li - , x MCl 6-x Br x , where 0 ≤ a ≤ 2 and 0 < x < 6.

[0007] The present invention is implemented as follows: In the first aspect, the present invention provides a core-shell structured halide solid electrolyte, and the chemical general formula of the solid electrolyte is Li 2+a MCl 6-x Br x , where M is one of Zr, Hf, Ta, Sn or Ce, and 0 ≤ a ≤ 2, 0 < x < 6; The solid electrolyte includes a core enriched in Cl - and a shell enriched in Br - , and from the core to the shell, the elemental ratio of Cl / Br changes in a continuous gradient.

[0008] In the second aspect, the present invention provides a precursor of a core-shell structured halide solid electrolyte, and the chemical general formula of the precursor is [Li2M(OH)6]Cl 6-x Br<"0000010">·mH2O, where 0 < x < 6, 0 < m < 4, and the elemental ratio of Cl / Br changes in a gradient from the inside to the outside. <00>

[0009] In the third aspect, the present invention provides a preparation method of a core-shell structured halide solid electrolyte, including the following steps: Add MCl x and LiCl to water, then add urea for hydrothermal reaction. After the reaction is completed, the precipitate is obtained after cooling, centrifugation and washing. The precipitate is ultrasonically dispersed in an alcohol solution to obtain a chlorine-rich layered double hydroxide suspension; Magnetically stir LiBr to completely dissolve it in a mixed solvent to form a LiBr solution. Under stirring conditions, slowly drop the chlorine-rich layered double hydroxide suspension into the LiBr solution. After the reaction is completed, centrifuge and collect the precipitate and wash it to obtain a gradient layered double hydroxide precursor; Vacuum dry the precursor to obtain a dry powder, heat-treat the dried powder, take out the sample after cooling, grind and sieve it to obtain the halide solid electrolyte. <00>

[0010] In some preferred embodiments, the hydrothermal reaction is carried out in a hydrothermal reactor at a temperature of 100-120°C for a reaction time of at least 36 hours.

[0011] In some preferred embodiments, the alcohol solution is at least one of ethanol, propanol or isopropanol, the ultrasonic power is 200-300W, the time is 20-40min, and the ultrasonic frequency is 20-40kHz.

[0012] In some preferred embodiments, the mixed solvent is anhydrous ethanol and water, with a volume ratio of anhydrous ethanol to water of (1-5):1.

[0013] In some preferred embodiments, the rate of vigorous stirring is 500-1500 rpm; the rate of slow dripping is 0.2 ml / s-1 ml / s.

[0014] In some preferred embodiments, the vacuum drying temperature is 60-120°C and the drying time is 6-12 hours.

[0015] In some preferred embodiments, the heat treatment is carried out under the protection of high-purity nitrogen or high-purity argon, with a heating rate of 2-5℃ / min, a heat treatment temperature of 150-350℃, and a heat treatment time of 8-12h.

[0016] In some preferred embodiments, the sieve used for sieving is 300-500 mesh.

[0017] The present invention has the following beneficial effects: (1) The halide solid electrolyte provided by this invention completely replaces traditional rare earth metals with inexpensive and abundant zirconium and hafnium elements, which significantly reduces raw material costs and resource dependence from the source. The unique core-shell structure successfully combines the advantages of different halide anions: the bromine-rich component of the outer shell provides extremely high ionic conductivity, ensuring rapid lithium ion transport; while the chlorine-rich component of the core acts as a structurally stable phase, giving the material excellent high voltage withstand capability, thus fundamentally solving the industry problem of the difficulty in balancing high ionic conductivity and high stability.

[0018] (2) The halide solid electrolyte provided by the present invention adopts the layered double hydroxide template method in the synthesis process, which realizes the atomic-level uniform mixing of the precursor under low temperature conditions. This not only avoids the problems of component volatilization and grain coarsening caused by high temperature sintering, but also significantly reduces energy consumption and ensures that the product has high purity and uniform morphology.

[0019] (3) The halide solid electrolyte core-shell structure particles provided by this invention can form a tight interfacial contact with the electrode active material, effectively reducing interfacial impedance and significantly suppressing harmful side reactions and lithium dendrite growth during cycling. In summary, this material system lays a solid material foundation for comprehensively improving the rate performance, cycle life and safety performance of all-solid-state batteries, and provides a key solution for their large-scale industrial application. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of SEM and TEM of the halide solid electrolyte provided in an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0023] Currently, while halide solid electrolytes exhibit high ionic conductivity and good antioxidant stability, their commercialization still faces significant obstacles. First, their core materials heavily rely on expensive rare earth elements such as yttrium, indium, and scandium, resulting in high raw material costs and hindering large-scale application. Second, there is an inherent contradiction in material performance: introducing larger anions such as bromine (Br) to improve ionic conductivity often sacrifices electrochemical oxidation stability; conversely, increasing chlorine (Cl) content to pursue high voltage stability restricts ion migration rates. This performance trade-off makes it difficult for a single homogeneous material to simultaneously meet the requirements of high conductivity and high stability. Furthermore, traditional synthesis mainly relies on energy-intensive high-temperature solid-state methods or mechanical ball milling methods that easily introduce impurities, making it difficult to precisely control the microstructure and morphology of the product. This leads to poor contact between the electrolyte and electrode, high interfacial impedance, and numerous side reactions, ultimately affecting the cycle life and safety of the battery.

[0024] Based on this, in a first aspect, the present invention provides a core-shell structured halide solid electrolyte, wherein the chemical formula of the solid electrolyte is Li. 2+a MCl 6-x Br x, where M is one of Zr, Hf, Ta, Sn or Ce, where 0 ≤ a ≤ 2, 0 < x < 6; The solid electrolyte includes a core enriched in Cl - and a shell enriched in Br - , and from the core to the shell, the elemental ratio of Cl / Br changes in a continuous gradient.

[0025] By using inexpensive and highly abundant non-rare-earth metals such as Zr and Sn, the inventors greatly reduce the material cost and ensure the safety and stability of the supply chain. The shell of the composite material is a Br-rich phase, which can provide excellent interfacial contact and lithium-ion transport channels. More importantly, the internal Cl-rich phase, as the "last line of defense", can more effectively resist oxidation decomposition under high voltage, thereby protecting the entire electrolyte particle and significantly improving the long-term compatibility with high-voltage cathodes (such as > 4.5V). The dense core-shell structured particles can form a denser electrolyte layer, effectively blocking the growth path of lithium dendrites.

[0026] In a second aspect, the present invention provides a precursor of a core-shell structured halide solid electrolyte, and the chemical general formula of the precursor is [Li2M(OH)6]Cl 6-x Br x ·mH2O, where 0 < x < 6, 0 < m < 4, and the elemental ratio of Cl / Br changes in a gradient from the inside to the outside.

[0027] In a third aspect, the present invention provides a preparation method of a core-shell structured halide solid electrolyte. First, a LDH precursor with a cheap metal as the center and chloride ions in the interlayer is synthesized by a hydrothermal method; subsequently, ion exchange technology is used to selectively replace the chloride ions in the outer layer of the particles with bromide ions, thereby constructing a compositional gradient structure with a Cl-rich core and a Br-rich shell; finally, low-temperature heat treatment is carried out to cause a topological transformation of the precursor, and this core-shell structure is perfectly inherited into the final halide electrolyte crystal. In the synthesis process, the high-energy-consuming solid-phase method (> 550 °C) and the mechanical ball-milling method that is prone to introducing impurities are completely abandoned, providing a low-temperature, energy-saving and efficient synthesis route. By treating the LDH precursor and low-temperature topological transformation, the hydrolysis problem of sensitive halides in the synthesis process is effectively avoided, ensuring the purity of the product.

[0028] The steps include: S1. Synthesize "Cl-rich core" LDH seeds: Add MCl x and LiCl to water, then add urea for hydrothermal reaction. After the reaction ends, the precipitate is obtained after cooling, centrifugation and washing, and the precipitate is ultrasonically dispersed in an alcohol solution to obtain a Cl-rich layered double hydroxide suspension.

[0029] In optional embodiments, M is a non-rare earth metal, including but not limited to Zr, Hf, Ta, Sn, or Ce.

[0030] In some preferred embodiments, the hydrothermal reaction includes the following steps: first, the mixed solution is placed in a hydrothermal reactor, sealed, and then placed in a forced-air drying oven at a temperature of 100-120°C for at least 36 hours.

[0031] In some preferred embodiments, the alcohol solution is at least one of ethanol, propanol or isopropanol, the ultrasonic power is 200-300W, the time is 20-40min, and the ultrasonic frequency is 20-40kHz.

[0032] S2, Br - Ion exchange to construct compositional gradient LDH: LiBr was completely dissolved in a mixed solvent by magnetic stirring to form a LiBr solution. Under stirring conditions, a chlorine-rich layered double hydroxide suspension was slowly added dropwise to the LiBr solution. After the reaction was completed, the precipitate was collected by centrifugation and washed to obtain the gradient layered double hydroxide precursor.

[0033] In some preferred embodiments, the mixed solvent is anhydrous ethanol and water, with a volume ratio of anhydrous ethanol to water of (1-5):1. The use of an ethanol-water mixed solvent is to control Br. - The exchange rate is adjusted to achieve gradient exchange.

[0034] In some preferred embodiments, the rate of vigorous stirring is 500-1500 rpm; the rate of slow dripping is 0.2 ml / s-1 ml / s.

[0035] S3. Topological transformation of gradient LDH precursor: The precursor is vacuum dried to obtain dry powder, the dried powder is heat-treated, the sample is taken out after cooling, ground and sieved to obtain halide solid electrolyte.

[0036] In some preferred embodiments, the vacuum drying temperature is 60-120℃ and the drying time is 6-12h; the heat treatment is carried out under the protection of high-purity nitrogen or high-purity argon, the heating rate is 2-5℃ / min, the heat treatment temperature is 150-350℃, and the heat treatment time is 8-12h; the sieve used for sieving is 300-500 mesh.

[0037] The final halide solid electrolyte will Cl - and Br - Atomic-level mixing, with each atom occupying the same set of anion sites in the crystal lattice, forms a uniform [MCl] 6-x Br x ] 4- Coordination octahedron.

[0038] It should be noted that the water used in the preparation method of the present invention is deionized water, and the washing solution is anhydrous ethanol.

[0039] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0040] Example 1 This embodiment provides a method for preparing a core-shell structured halide solid electrolyte, the steps of which include: S1. Dissolve ZrOCl2·8H2O (3.22 g, 10 mmol) and LiCl (2.12 g, 50 mmol) in 40 mL of deionized water, and add urea (3.60 g, 60 mmol). Transfer to a 100 mL hydrothermal reactor and react at 100 °C for 36 hours. Centrifuge, wash with ethanol to obtain a white precipitate, redisperse in 20 mL of ethanol to obtain a suspension; S2. Dissolve LiBr (4.34 g, 50 mmol) in a mixed solvent of 20 mL ethanol and 5 mL water to obtain a LiBr solution. Under vigorous stirring and at 40 °C, slowly add the suspension dropwise to the LiBr solution and continue the reaction for 12 hours. After centrifugation, wash with ethanol to obtain the precipitate. S3. The obtained precipitate was vacuum dried at 60°C in a glove box. The dried powder was placed in a tube furnace and heated to 280°C at a rate of 2°C / min under an argon atmosphere, held at that temperature for 10 hours, and then cooled with the furnace. Core-shell structured Li2ZrCl4Br2 was obtained.

[0041] The core-shell structured Li2ZrCl4Br2 powder was examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), such as... Figure 1 As shown, the main image is a SEM image of the core-shell structure Li₂ZrCl₄Br₂, and the inset in the upper left corner is a TEM image of the material. The SEM image shows that the material is composed of micron-sized particles with a relatively rough surface. The particle size is in the range of tens of micrometers, and there is a certain degree of aggregation between the particles. The TEM inset in the upper left corner further reveals a clear core-shell interface structure, indicating that the material has indeed formed a composite structure with a separated core and shell. This structure helps to improve the controllability of the ion transport path and the stability of the interface.

[0042] Example 2 This embodiment provides a method for preparing a core-shell structured halide solid electrolyte, the steps of which are the same as those in Example 1, except that ZrOCl2·8H2O is replaced with an equimolar amount of HfOCl2·8H2O, and Li2HfCl4Br2 is finally obtained.

[0043] Example 3 This embodiment provides a method for preparing a core-shell structured halide solid electrolyte, the steps of which are the same as those in Example 1, except that 1.69g LiCl (40mmol) and 2.6g LiBr (mmol) are used to keep the total molar amount of halogen constant, and Li2ZrCl3Br3 is finally obtained.

[0044] Comparative Example 1 This comparative example provides a method for preparing a halide solid electrolyte, the steps of which are the same as in Example 1, except that: ZrOCl2·8H2O (3.22 g, 10 mmol), LiCl (1.69 g, 40 mmol), LiBr (2.60 g, 30 mmol), and urea (3.60 g, 60 mmol) are dissolved in 80 mL of water at once, and the reaction is carried out directly at 100 °C for 36 h using hydrothermal methods. The final product is Li2ZrCl3Br3 without a core-shell structure.

[0045] Comparative Example 2 This comparative example provides a method for preparing a halide solid electrolyte, which includes the following steps: weighing Y2O3 and LiCl according to a stoichiometric ratio, sintering at 550°C for 20 hours using a high-temperature solid-state method, and then grinding to obtain the product, thus obtaining homogeneous Li3YCl6 synthesized by the conventional solid-state method.

[0046] Comparative Example 3 This comparative example provides a method for preparing a halide solid electrolyte, which includes the following steps: LiCl, LiBr and ZrCl4 powders are stoichiometrically ball-milled in a planetary ball mill at 500 rpm for 10 hours to obtain homogeneous Li2ZrCl3Br3 synthesized by mechanical ball milling.

[0047] Experimental Example 1 The conductivity and cycle capacity retention of the halide solid electrolytes prepared in each embodiment and comparative example were tested.

[0048] Conductivity testing methods: (1) Weigh 200mg of solid electrolyte, pour it into the mold, manually rotate it until it is even and flat, apply pressure of 108MPa, and hold the pressure for 1min; (2) Measure the thickness of the pressed electrolyte sheet using a micrometer and record the data; (3) Place the small mold into the metal kit, apply pressure of 216 MPa, and tighten the three knobs on the kit; (4) Use an electrochemical workstation to test the impedance of the mold battery and record the electrolyte resistance.

[0049] (5) Then the ionic conductivity of the membrane at 25°C is calculated using the following formula.

[0050]

[0051] Where σ is the ionic conductivity (S / cm), L is the compacted thickness of the composite solid electrolyte (cm), R is the resistance perpendicular to the electrolyte powder surface (Ω), and S is the effective electrolyte area (cm²). 2 ).

[0052] Cyclic capacity retention calculation method (1) According to the ratio of active material: above synthesized halide solid electrolyte: VGCF=85:13:2, add the material into a mortar and grind for 10 min to make a composite positive electrode; (2) Weigh 100 mg of sulfide solid electrolyte (LPSC), pour it into the mold, manually rotate it until it is even and flat, apply pressure of 108 MPa, and hold the pressure for 1 min; (3) Weigh 20mg of composite positive electrode, pour it into the mold, manually rotate it until it is uniform and flat, apply pressure of 324MPa, and hold the pressure for 1min; (4) Add the indium sheet (ø10mm) and lithium sheet (ø3mm) to the negative electrode side, apply a pressure of 36MPa, and hold the pressure for 30s; (5) Place the small mold into the metal kit, apply pressure of 216 MPa, and tighten the three knobs on the kit; (6) First, perform 3 charge-discharge cycles at 0.1C, and then perform 200 charge-discharge cycles at 1C.

[0053] The relevant data is shown in Table 1.

[0054] Table 1. Test results of the examples and comparative examples

[0055] Based on the test results in Table 1, it can be seen that the halide solid electrolyte with a core-shell structure design is significantly superior to the material obtained by the traditional synthesis method in terms of ionic conductivity and cycle stability. The core-shell structure electrolytes prepared in Examples 1, 2, and 3 have ionic conductivity of 1.06 × 10⁻⁶ at 25 °C. -3 S / cm, 0.97×10 -3 S / cm and 1.12×10 -3 S / cm were significantly higher than those of Comparative Example 1 (0.83 × 10⁻⁶). -3 S / cm), Comparative Example 2 (0.51×10 -3 S / cm) and Comparative Example 3 (0.74×10 -3(S / cm). In Example 3, the highest conductivity was achieved by adjusting the ratio of LiCl to LiBr while keeping the total molar amount of halogen constant, indicating that optimizing the halogen ratio in the core-shell structure helps to further improve ion transport performance.

[0056] In terms of battery cycle performance, the core-shell structured materials also exhibited superior capacity retention. After 200 cycles at 1C, Examples 1, 2, and 3 showed capacity retention of 96.5%, 95.7%, and 95.9%, respectively, significantly higher than Comparative Example 1 (90.1%), Comparative Example 2 (88.3%), and Comparative Example 3 (89.6%). Comparative Example 1, in particular, although its chemical composition was the same as Example 3, failed to form a core-shell structure due to a one-step hydrothermal synthesis method, resulting in decreased conductivity and cycle stability. This demonstrates that the core-shell interface structure plays a crucial role in suppressing interfacial side reactions and maintaining electrode / electrolyte interface stability.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A core-shell structured halide solid electrolyte, characterized in that, The general chemical formula of the solid electrolyte is Li 2+a MCl 6-x Br x M is one of Zr, Hf, Ta, Sn or Ce, where 0 ≤ a ≤ 2, 0 <x<6; The solid electrolyte includes Cl-enriched - The kernel and enriched Br - The shell has a continuous gradient in the Cl / Br elemental ratio from the core to the shell.

2. A precursor for synthesizing a core-shell structured halide solid electrolyte as described in claim 1, characterized in that, The chemical general formula of the precursor is [Li2M(OH)6]Cl 6-x Br x ·mH2O, where 0 < x < 6, 0 < m < 4, and the elemental ratio of Cl / Br changes in a gradient from the inside to the outside.

3. A method for preparing a core-shell structured halide solid electrolyte as described in claim 1, characterized in that, Includes the following steps: MCI x LiCl was added to water, and then urea was added to carry out a hydrothermal reaction. After the reaction was completed, the precipitate was obtained by cooling, centrifugation, and washing. The precipitate was then ultrasonically dispersed in an alcohol solution to obtain a chlorine-rich layered double hydroxide suspension. LiBr was completely dissolved in a mixed solvent by magnetic stirring to form a LiBr solution. Under stirring conditions, a chlorine-rich layered double hydroxide suspension was slowly added dropwise to the LiBr solution. After the reaction was completed, the precipitate was collected by centrifugation and washed to obtain the gradient layered double hydroxide precursor. The precursor was vacuum dried to obtain a dry powder. The dried powder was then heat-treated, cooled, and the sample was taken out, ground, and sieved to obtain a halide solid electrolyte.

4. The method for preparing a core-shell structured halide solid electrolyte according to claim 3, characterized in that, The hydrothermal reaction is carried out in a hydrothermal reactor at a temperature of 100-120°C for at least 36 hours.

5. The method for preparing a core-shell structured halide solid electrolyte according to claim 3, characterized in that, The alcohol solution is at least one of ethanol, propanol or isopropanol, the ultrasonic power is 200-300W, the time is 20-40min, and the ultrasonic frequency is 20-40kHz.

6. The method for preparing a core-shell structured halide solid electrolyte according to claim 3, characterized in that, The mixed solvent is anhydrous ethanol and water, with a volume ratio of (1-5):

1.

7. The method for preparing a core-shell structured halide solid electrolyte according to claim 3, characterized in that, The rate of vigorous stirring is 500-1500 rpm; the rate of slow dripping is 0.2 ml / s-1 ml / s.

8. The method for preparing a core-shell structured halide solid electrolyte according to claim 3, characterized in that, The vacuum drying temperature is 60-120℃, and the drying time is 6-12 hours.

9. The method for preparing a core-shell structured halide solid electrolyte according to claim 3, characterized in that, The heat treatment is carried out under the protection of high-purity nitrogen or high-purity argon, with a heating rate of 2-5℃ / min, a heat treatment temperature of 150-350℃, and a heat treatment time of 8-12h.

10. The method for preparing a core-shell structured halide solid electrolyte according to claim 3, characterized in that, The sieve used for sieving has a mesh size of 300-500.

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