Nanoscale chloride solid electrolyte and preparation method thereof

Abstract

The invention relates to the technical field of solid-state batteries, in particular to a nanoscale chloride solid-state electrolyte and a preparation method thereof. The preparation method comprises the following steps: S1, respectively removing impurities from LiCl and metal chloride MCln in a polar solvent; wherein M comprises at least one of Y, Er, Ho, Dy, Gd, Sm, Tb, Zr and Hf; s2, mixing the impurity-removed LiCl solution with an MCln solution, adding a non-polar solvent, and carrying out sanding treatment to obtain nanoscale solid electrolyte slurry; s3, after solid-liquid separation, carrying out supercritical CO2 drying to obtain nano solid electrolyte powder with the water content of less than 2000ppm; and S4, forming a hydrophobic passivation layer on the surface of the electrolyte material through jet milling. According to the method, the nanoscale chloride solid electrolyte can be prepared, the purity is high, and the electrochemical performance is good.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and more specifically, to a nanoscale chloride solid electrolyte and its preparation method. Background Technology

[0002] All-solid-state batteries (ASSBs) have attracted widespread attention due to their enhanced safety and the potential for high energy density when matched with low-potential, high-capacity anodes. Among solid-state battery materials, chloride electrolytes have seen rapid development in recent years, becoming a competitive candidate material due to their unique performance combination. Several high-performance chloride solid-state electrolytes (such as Li3YCl6, Li3InCl6, Li2ZrCl6, and their doped or substituted variants) can achieve lithium-ion conductivity of up to 10⁻⁶ at room temperature. - 3 The S / cm range is comparable to the current best-performing sulfide solid electrolytes (such as Li). 10 GeP2S 12 Comparable to, and even superior to, some systems, and far superior to typical oxide solid electrolytes (typically 10). -6 -10 -4 This is mainly due to its three-dimensional ion diffusion channels, moderate lattice energy, and tunable crystal structure (e.g., the trigonal crystal system of Li3MCl6 and the monoclinic crystal system of Li2MCl6), which are conducive to the rapid migration of lithium ions.

[0003] However, existing synthesis methods (such as solid-phase, melt, and aqueous methods) generally suffer from inaccurate particle size control, with particle size deviations typically exceeding 10%, and the original particle sizes are mostly tens of micrometers, making them unsuitable for direct use as solid electrolytes. They must undergo multi-step grinding processes to reduce the particle size to submicron or nanometer levels. Even during grinding, uneven particle size distribution persists, easily leading to micron-sized agglomerates (D50 deviation > 10%), resulting in poor electrode-electrolyte interface contact. Currently, mechanical crushing methods such as wet ball milling and sand milling are the main processes for preparing chloride solid electrolytes. However, mechanical crushing processes can easily induce Cl... - The water evaporates and forms a ≡M–OH structure, thus exacerbating the material's adsorption of moisture. Using solid electrolytes with high moisture content in cathode blending or electrolyte membranes significantly reduces battery performance, causing problems such as high-temperature capacity decay and decreased cycle performance. Therefore, how to effectively control Cl... - Achieving synergistic control over particle nano-sizing and surface passivation while simultaneously volatile matter and oxygen-containing impurities are formed has become a key challenge in driving the industrial application of chloride solid electrolytes.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a nanoscale chloride solid electrolyte and its preparation method. This method enables the preparation of nanoscale chloride solid electrolytes with high purity and can inhibit Cl... - The evaporation and formation of oxygen-containing impurities improve the electrochemical performance of the electrolyte, while also forming a passivation layer on the electrolyte surface, giving it high environmental stability and interfacial compatibility. This solves the technical problems of low purity, difficulty in controlling nano-sizing, strong water absorption and severe agglomeration, and low conductivity in the preparation of solid electrolytes by the dissolution method in the prior art.

[0006] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A method for preparing a nanoscale chloride solid electrolyte includes the following steps: S1. Mix LiCl with a first polar solvent to perform the first impurity removal, and obtain a first solution; Metal chloride MCl n The solution is mixed with a second polar solvent to perform a second purification process, resulting in a second solution; wherein M includes at least one of Y, Er, Ho, Dy, Gd, Sm, Tb, Zr, and Hf. S2. Mix the first solution with the second solution, add a non-polar solvent, and perform sand milling to obtain a nanoscale solid electrolyte slurry; S3. After solid-liquid separation of the nanoscale solid electrolyte slurry, supercritical CO2 drying is performed to obtain nanoscale solid electrolyte powder material with a water content of <2000ppm.

[0007] Preferably, the method further includes the following steps: S4. Using a mixed gas containing gaseous halohydrocarbons and inert gases as a gas source, the nano-solid electrolyte powder material is subjected to airflow pulverization to form a passivation layer on its surface, thereby obtaining the nano-scale chloride solid electrolyte.

[0008] Preferably, in step S1, the first polar solvent and the second polar solvent each independently include at least one of formamide, ethanol, glycerol, and propylene glycol.

[0009] Preferably, in step S1, the nonpolar solvent includes at least one of benzene, carbon tetrachloride, isooctane, toluene, dichloromethane, n-hexane, cyclohexane, heptane, and liquid paraffin.

[0010] Preferably, in step S1, the first impurity removal includes: adding oxalic acid solution dropwise under stirring until the pH is 3-5, filtering to remove insoluble matter, and obtaining the first solution; wherein the oxalic acid solution includes an aqueous solution of oxalic acid and / or an ethanol solution of oxalic acid.

[0011] Preferably, in step S1, the second impurity removal includes: adding an alkaline solution dropwise under stirring until the pH is 9-10, separating the precipitate, collecting the filtrate, and obtaining the second solution; wherein the alkaline solution includes an aqueous solution of NaOH and / or ammonia.

[0012] Preferably, in step S2, when mixing the first solution and the second solution, the molar ratio of Li to metal M is 2-5:1.

[0013] Preferably, in step S2, the LiCl and the MCl n The total mass to the volume ratio of the nonpolar solvent is (1-100) g : (5-200) mL.

[0014] Preferably, in step S2, the total volume ratio of the first polar solvent and the second polar solvent to the volume ratio of the nonpolar solvent is 1:1-2.

[0015] Preferably, in step S2, the sand milling process takes 1-3 hours and the power of the sand milling process is 10-20 kW.

[0016] Preferably, in step S3, the pressure of the supercritical CO2 drying is 10-15 MPa and the temperature is 170-230℃.

[0017] Preferably, in step S4, the gaseous halohydrocarbon includes one or more of chloromethane, chloroethane, bromomethane, and bromoethane.

[0018] Preferably, in step S4, the volume concentration of the gaseous halohydrocarbon in the mixed gas is 0.5%-50%.

[0019] Preferably, in step S4, during the airflow pulverization process, the pressure of the mixed gas is 0.5-2 MPa, the temperature of the mixed gas is 80-200°C, and the flow rate of the mixed gas is 1-10 m³ / s. 3 / min.

[0020] A nanoscale chloride solid electrolyte is prepared by the preparation method of the nanoscale chloride solid electrolyte described in any of the preceding embodiments.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention employs a dual purification mechanism to solve the problem of decreased conductivity caused by precursor impurities; the purified LiCl solution and MCl... nThe solution is mixed and injected with a non-polar solvent to form a polar-non-polar mixed solvent system. Sand milling is carried out in this system, which can promote the crushing and nano-sizing of the raw materials. At the same time, the non-polar solvent can effectively block the side reaction of metal ion hydrolysis, thereby expanding the microscopic contact surface of the precursor powder material and ensuring the high purity and high conductivity of the solid electrolyte. Finally, by combining supercritical drying and in-situ vacuum packaging technology, high-purity, high-conductivity nano-sized solid electrolyte materials can be obtained.

[0022] This invention achieves deagglomeration and hydrophobicity simultaneously through airflow pulverization, forming an alkoxy passivation layer on the surface of the nano-solid electrolyte. The treated nano-chloride solid electrolyte powder has less agglomeration, is easy to disperse, has good powder flowability, low water content, and low water absorption rate in air and water. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 The X-ray diffraction patterns of the Li3InCl6 solid electrolytes prepared in Example 1 and Comparative Example 1 of this invention are shown below. Figure 2 This is a SEM image of the Li3InCl6 solid electrolyte prepared in Example 1 of the present invention; Figure 3 This is a SEM image of the aqueous phase synthesis of Li3InCl6 solid electrolyte in Comparative Example 1 of this invention. Figure 4 This is a particle size distribution diagram of the Li3InCl6 solid electrolyte prepared in Example 1 of the present invention; Figure 5 The above is a charge-discharge curve of the all-solid-state battery assembled using the Li3InCl6 solid-state electrolyte in Example 1 of this invention. Figure 6 The charge-discharge curves are shown for the all-solid-state battery assembled using the Li3InCl6 solid-state electrolyte in Comparative Example 1 of this invention. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0026] The first aspect of this invention provides a method for preparing a nanoscale chloride solid electrolyte, comprising the following steps: S1. Mix LiCl with a first polar solvent to perform the first impurity removal, and obtain a first solution; Metal chloride MCl n The solution is mixed with a second polar solvent to perform a second purification process, resulting in a second solution; wherein M includes at least one of Y, Er, Ho, Dy, Gd, Sm, Tb, Zr, and Hf. S2. Mix the first solution and the second solution, add a non-polar solvent, and perform sand milling to obtain a nanoscale solid electrolyte slurry; S3. After solid-liquid separation of the nanoscale solid electrolyte slurry, supercritical CO2 drying is performed to obtain nanoscale solid electrolyte powder material with a water content of <2000ppm, and then vacuum packaging is carried out in situ.

[0027] This invention removes LiCl and MCl through a dual impurity removal process. n The impurity ions in the precursor solution solved the problem of decreased conductivity caused by precursor impurities; the purified LiCl solution and MCl n The solution is mixed and injected with a non-polar solvent to form a polar-non-polar environment system. Nanoparticles are then milled within this system. The non-polar solvent blocks the hydrolysis side reactions of metal ions. Combined with supercritical drying technology and in-situ vacuum packaging, the material itself is better protected, thereby improving the purity and conductivity of the solid electrolyte. Supercritical CO2 drying eliminates the sintering and hard agglomeration of nanoparticles caused by capillary forces during traditional drying processes.

[0028] In some specific embodiments of the present invention, the following steps are also included: S4. Using a mixed gas containing gaseous halohydrocarbons and inert gases as a gas source, the nano-solid electrolyte powder material is subjected to airflow pulverization to form a passivation layer on its surface, thereby obtaining nano-sized chloride solid electrolyte.

[0029] This invention employs supercritical CO2 drying to eliminate nanoparticle sintering caused by capillary forces, and then uses airflow pulverization to achieve hydrophobicity. Fluidized bed pulverization is performed using a mixture of inert gas (such as N2) and haloalkanes. During this process, the haloalkanes form molecular bonds with the groups on the powder surface, forming a hydrophobic MOR (M represents a metal element, R represents an alkyl group) on the surface, forming a chemically bonded alkoxy passivation layer (2-5 nm thick), simultaneously achieving depolymerization and hydrophobicity. Moreover, the nano-solid electrolyte powder after hydrophobic treatment has less agglomeration, is easy to disperse, has good powder flowability, low water content, and low water absorption rate in air and water. Therefore, the preparation of nano-solid electrolyte membranes using it has the advantages of low water content and low drying temperature.

[0030] In some specific embodiments of the present invention, in step S1, the first polar solvent and the second polar solvent each independently include at least one of formamide, ethanol, glycerol, and propylene glycol; wherein the first polar solvent and the second polar solvent may be the same or different.

[0031] In some specific embodiments of the present invention, in step S1, the nonpolar solvent used includes at least one of benzene, carbon tetrachloride, isooctane, toluene, dichloromethane, n-hexane, cyclohexane, heptane, and liquid paraffin; preferably cyclohexane and / or isooctane.

[0032] In some specific embodiments of the present invention, step S1, the first impurity removal includes: mixing LiCl with a first polar solvent, then adding oxalic acid solution dropwise under stirring until the pH is 3-5, filtering to remove insoluble matter, and obtaining a first solution; wherein the oxalic acid solution includes an aqueous solution of oxalic acid and / or an ethanolic solution of oxalic acid; adjusting the pH of the LiCl solution with oxalic acid to selectively precipitate Ca. 2+ Mg 2+ Divalent ions form oxalate precipitates, which are then removed by filtration.

[0033] In some specific embodiments of the present invention, step S1 includes: removing impurities from MCl. n After mixing with the second polar solvent, an alkaline solution is added dropwise under stirring until the pH reaches 9-10. The precipitate is separated, and the filtrate is collected to obtain the second solution. The alkaline solution includes an aqueous solution of NaOH and / or ammonia. MCl n Introducing an alkaline solution into the solution causes Fe to... 3+ Al 3+ The hydroxide precipitate is formed, which effectively removes impurities such as Fe and Al.

[0034] This invention effectively removes LiCl and MCl through a dual impurity removal process. n Impurities in the raw materials have solved the problem of decreased conductivity caused by precursor impurities.

[0035] In some specific embodiments of the present invention, in step S2, when mixing the first solution and the second solution, the molar ratio of Li to metal M in the solution is 2-5:1. For example, it can be any one value or a range of any two values ​​from 2:1, 3:1, 4:1, 5:1.

[0036] In some specific embodiments of the present invention, in step S2, LiCl and MCl n The total mass to the volume ratio of the nonpolar solvent is (1-100) g: (5-200) mL. For example, it can be any one value or a range of any two values ​​among 1 g: 5 mL, 50 g: 200 mL, 50 g: 150 mL, and 100 g: 200 mL.

[0037] In some specific embodiments of the present invention, in step S2, the total volume ratio of the first polar solvent and the second polar solvent to the volume ratio of the nonpolar solvent is 1:1-2. For example, it can be any one value or a range of any two values ​​among 1:1, 1:1.2, 1:1.5, 1:1.8, and 1:2.

[0038] In some specific embodiments of the present invention, in step S2, the grinding time is 1-3 hours, for example, it can be any one value or a range of any two values ​​from 1 hour, 1.5 hours, 2 hours, 2.5 hours, and 3 hours; the grinding power is 10-20 kW, for example, it can be any one value or a range of any two values ​​from 10 kW, 12 kW, 15 kW, 18 kW, and 20 kW; the purpose of grinding is to break down the raw materials and then nanoscale them.

[0039] In some specific embodiments of the present invention, in step S3, the solid-liquid separation method includes centrifugation, discarding the supernatant, and then drying using supercritical CO2 drying technology.

[0040] In some specific embodiments of the present invention, in step S3, the pressure of supercritical CO2 drying is 10-15 MPa, for example, it can be any one value or a range of any two values ​​among 10 MPa, 12 MPa, 14 MPa, and 15 MPa; the temperature is 170-230°C, for example, it can be any one value or a range of any two values ​​among 170°C, 190°C, 200°C, 210°C, and 230°C.

[0041] In some specific embodiments of the present invention, in step S4, the gaseous halohydrocarbon used includes one or more of chloromethane, chloroethane, bromomethane, and bromoethane.

[0042] In some specific embodiments of the present invention, in step S4, the volume concentration of gaseous haloalkanes in the mixed gas is 0.5%-50%, for example, it can be any one value or a range of any two values ​​from 0.5%, 1%, 5%, 10%, 20%, 30%, 40%, 50%.

[0043] In some specific embodiments of the present invention, in step S4, during the airflow pulverization process, the pressure of the mixed gas is 0.5-2 MPa, for example, it can be any single value or a range of any two values ​​among 0.5 MPa, 1 MPa, 1.5 MPa, and 2 MPa; the temperature of the mixed gas is 80-200°C, for example, it can be any single value or a range of any two values ​​among 80°C, 100°C, 120°C, 150°C, 180°C, and 200°C; the flow rate of the mixed gas is 1-10 m³ / s. 3 / min, for example, can be 1m 3 / min, 3m 3 / min, 5m 3 / min, 8m 3 / min, 10m 3 / min represents any single point value or a range of any two point values.

[0044] A second aspect of the present invention provides a nanoscale chloride solid electrolyte, which is prepared by the method for preparing nanoscale chloride solid electrolyte as described in any of the foregoing embodiments.

[0045] The embodiments of the present invention will be described in detail below with reference to specific examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0046] Example 1 S1. Dissolve 36.50 g LiCl in 100 mL of anhydrous ethanol, add oxalic acid in ethanol solution until pH≈4.0, filter to remove insoluble matter, and obtain the first solution; Dissolve 63.50 g InCl3 in 50 mL of anhydrous ethanol, then add ammonia dropwise until pH≈9.5, separate the hydroxide precipitate (containing impurities such as Fe and Al), collect the filtrate to obtain the second solution; S2. Add the first solution, the second solution, and 200 mL of cyclohexane to a sand mill and mill for 1 h at a power of 15 kW. S3. Centrifuge the slurry after sand milling (5000 rpm × 15 min) and discard the supernatant; use a supercritical CO2 drying device to dry the solid material after centrifugation at a pressure of 12 MPa and a temperature of 200℃, and the moisture content after drying is less than 2000 ppm. S4. The powder obtained from supercritical CO2 drying is fed into an air jet mill. The volume ratio of ethane monochloroto nitrogen (N2) is controlled at 5:95 using a volumetric flow meter, and the flow rate of the mixed gas is 8.5 m³ / s. 3 The gas flow rate is 2 MPa, and the gas mixture is used as the gas source for airflow pulverization. The heater of the gas source is adjusted to make the gas temperature 80℃. In the pulverization chamber, the high-pressure gas mixture carries the powder through the supersonic nozzle and collides with each other. During the collision, ethane monochloroite adsorbs onto the surface of LIC (Li3InCl6), thereby making the powder surface hydrophobic. The powder in the pulverization chamber is screened out to obtain LIC powder with qualified particle size by the action of the classifying wheel.

[0047] Comparative Example 1 The specific steps for synthesizing Li3InCl6 solid electrolyte using the traditional aqueous phase method are as follows: (1) Weigh out 100 g of LiCl and InCl3·4H2O in a molar ratio of 3:1 according to the stoichiometric ratio of Li3InCl6; (2) Place the weighed raw materials into a beaker, add 100 ml of deionized water, and stir for 10 min; (3) Heat the mixed solution to 200 °C in a vacuum drying oven and keep it at that temperature for 3 h; (4) After the heat treatment, the sample was naturally cooled to room temperature to obtain Li3InCl6 solid electrolyte.

[0048] Example 2 S1. Dissolve 30.25g LiCl in 100mL anhydrous ethanol, add oxalic acid ethanol solution to pH≈4.0, filter to remove insoluble matter, and obtain the first solution; Dissolve 69.75g YCl3 in 50mL of anhydrous ethanol, then add ammonia dropwise until pH≈9.5, separate the hydroxide precipitate (containing impurities such as Fe and Al), collect the filtrate to obtain the second solution; S2. Add the first solution, the second solution, and 200 mL of cyclohexane to a sand mill and mill for 1 h at a power of 15 kW. S3. Centrifuge the slurry after sand milling (5000 rpm × 15 min) and discard the supernatant; use a supercritical CO2 dryer to dry the solid material after centrifugation at a pressure of 12 MPa and a temperature of 200℃, and the moisture content after drying is less than 2000 ppm. S4. The powder obtained from supercritical CO2 drying is fed into an air jet mill. The volume ratio of ethane monochloroto nitrogen (N2) is controlled at 5:95 using a volumetric flow meter, and the flow rate of the mixed gas is 8.5 m³ / s. 3 The gas flow rate is 2 MPa, and the mixed gas is used as the gas source for airflow pulverization. The heater of the gas source is adjusted to make the gas temperature 80℃. In the pulverization chamber, the high-pressure mixed gas carries the powder through the supersonic nozzle and collides with each other. During the collision, ethane monochlorogas adsorbs onto the surface of Li3YCl6, thereby making the powder surface hydrophobic. The powder in the pulverization chamber is screened by the classifying wheel to separate Li3YCl6 powder with qualified particle size. The particle size of the powder is controlled at about 800 nm.

[0049] Comparative Example 2 The specific steps for synthesizing Li3YCl6 solid electrolyte using the traditional melt method are as follows: (1) Weigh 100g of LiCl and YCl3 in a molar ratio of 2:1 according to the stoichiometric ratio of Li3YCl6; (2) Vacuum seal the weighed raw materials; (3) Heat the sealed container with the tube to 300 °C at a heating rate of 5 °C / min and keep it at that temperature for 3 h; (4) After the heat treatment, the sample was naturally cooled to room temperature to obtain Li3YCl6 solid electrolyte.

[0050] Example 3 S1. Dissolve 26.67g LiCl in 100mL anhydrous ethanol, add oxalic acid ethanol solution to pH≈4.0, filter to remove insoluble matter, and obtain the first solution; Dissolve 73.33g ZrCl4 in anhydrous ethanol solution, then add ammonia dropwise until pH≈9.5, separate the hydroxide precipitate (containing impurities such as Fe and Al), collect the filtrate to obtain the second solution; S2. Add the first solution, the second solution, and 200 mL of cyclohexane to a sand mill and mill for 1 h at a power of 15 kW. S3. Centrifuge the slurry after sand milling (5000 rpm × 15 min) and discard the supernatant; use a supercritical CO2 dryer to dry the solid material after centrifugation at a pressure of 12 MPa and a temperature of 200℃, and the moisture content after drying is less than 2000 ppm. S4. The powder obtained from supercritical CO2 drying is fed into an air jet mill. The volume ratio of ethane monochloroto nitrogen (N2) is controlled at 5:95 using a volumetric flow meter, and the flow rate of the mixed gas is 8.5 m³ / s. 3The gas flow rate is 2 MPa, and the mixed gas is used as the gas source for airflow pulverization. The heater of the gas source is adjusted to make the gas temperature 80℃. In the pulverization chamber, the high-pressure mixed gas carries the powder through the supersonic nozzle and collides with each other. During the collision, ethane monochlorogas adsorbs onto the surface of Li2ZrCl6, thus making the powder surface hydrophobic. The powder in the pulverization chamber is screened by the classifying wheel to separate Li2ZrCl6 powder with qualified particle size. The particle size of the powder is controlled at about 800 nm.

[0051] Comparative Example 3 The specific steps for synthesizing Li₂ZrCl₆ solid electrolyte using a traditional solid-state reaction method are as follows: (1) Weigh 100 g of LiCl3 and ZrCl4 in a molar ratio of 2:1 according to the stoichiometric ratio of Li2ZrCl6; (2) The weighed raw materials were added to a ball mill jar and milled at 350 rpm for 6 h to obtain Li2ZrCl6 solid electrolyte.

[0052] Test case 1. X-ray diffraction analysis The phase composition of the Li3InCl6 solid electrolytes prepared in Example 1 and Comparative Example 1 was analyzed using X-ray diffraction, and the results are as follows: Figure 1 As shown in the figure, the diffraction peaks of the Li3InCl6 solid electrolyte prepared in Example 1 are consistent with those of the standard card PDF#97-008-9617, and the diffraction peaks have high intensity and narrow half-peak width, indicating that the product has high purity and good crystallinity.

[0053] 2. SEM testing The SEM images of the Li3InCl6 solid electrolyte in Example 1 and Comparative Example 1 were obtained by scanning electron microscopy. The SEM image of the electrolyte in Example 1 is shown below. Figure 2 As shown, the Li3InCl6 particles prepared by the wet method in Example 1 are irregularly shaped lumps with a uniform particle size distribution and an average particle size of approximately 600 nm; the SEM image of the electrolyte in Comparative Example 1 is shown below. Figure 3 As shown, the Li3InCl6 solid electrolyte synthesized by the traditional aqueous phase method exhibits agglomeration. The agglomerates are large in size and cannot be used directly as solid electrolytes.

[0054] 3. Particle size distribution The particle size distribution of the Li3InCl6 solid electrolyte in Example 1 was determined using wet laser particle size analysis with a laser particle size analyzer. The results are as follows: Figure 4As shown, the particle size distribution results indicate that the Li3InCl6 prepared in Example 1 has a D50 of 0.89 μm and a D90 of 1.82 μm. The chloride solid electrolyte powder prepared by the method of this invention exhibits a unimodal particle size distribution, mainly distributed in the nanometer range, with the powder being predominantly composed of single particles and not agglomerated.

[0055] 4. Ionic conductivity test The ionic conductivity of Li3InCl6 prepared in Example 1 and Comparative Example 1 was tested using the AC impedance method; the test results are shown in Table 1. The ionic conductivity was measured using an electrochemical workstation at a constant voltage AC impedance, obtaining the room temperature impedance value R of each electrolyte composite material. After testing, the samples were demolded, and the thickness l of the electrolyte composite material and the area S of the disc were measured. Then, according to Ohm's law R = l / (σ×S), the room temperature lithium-ion conductivity of the electrolyte sheet was calculated.

[0056] 5. Battery performance test The positive electrode material of the all-solid-state battery is a nickel-cobalt-manganese ternary cathode material (NCM811), while the negative electrode is a Li-In alloy. On the positive electrode side, the chloride solid electrolyte material prepared in the above examples and comparative examples was used, while on the negative electrode side, a conventional sulfide (Li6PS5Cl) electrolyte material was selected. During the assembly of the all-solid-state battery, appropriate pressure was applied to each layer of material; the electrolyte layer was subjected to a pressure of 2 MPa, and the battery layer was subjected to a pressure of 3 MPa. The electrolyte from Comparative Example 1 was used after being ground in a mortar for 15 minutes.

[0057] The electrochemical performance of the prepared all-solid-state batteries was tested. The solid-state battery samples were placed in a test fixture and then placed in a constant temperature chamber at 45°C for 120 minutes. They were then charged at 0.1C to 3.7V, allowed to stand for 5 minutes, and discharged to 1.9V to test the first-cycle efficiency (first-cycle efficiency). The test results are shown in Table 1.

[0058] Table 1

[0059] The charge-discharge curves of the all-solid-state batteries prepared with solid electrolytes in Example 1 and Comparative Example 1 are as follows: Figure 5 and Figure 6 As shown; from Table 1 and Figure 5 , Figure 6 It is evident that the chloride solid electrolyte prepared by the method of the present invention has better electrochemical performance.

[0060] This invention solves the problems of poor interfacial contact, low ion transport efficiency, and poor batch stability of existing halide solid electrolyte materials by precisely controlling the particle size and morphology of halide solid electrolyte nanomaterials and combining them with an efficient synthesis process. It provides a feasible solution for the preparation of high-performance electrolytes for solid-state batteries and has significant technical value and application prospects.

[0061] 6. ICP analysis was performed on the solid electrolytes prepared in Example 1 and Comparative Example 1, respectively. The test results of Example 1 are shown in Table 2, and the test results of Comparative Example 1 are shown in Table 3.

[0062] Table 2

[0063] Table 3

[0064] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing a nanoscale chloride solid electrolyte, characterized in that, Includes the following steps: S1. Mix LiCl with a first polar solvent to perform the first impurity removal, and obtain a first solution; Metal chloride MCl n The solution is mixed with a second polar solvent to perform a second purification process, resulting in a second solution; wherein M includes at least one of Y, Er, Ho, Dy, Gd, Sm, Tb, Zr, and Hf. S2. Mix the first solution with the second solution, add a non-polar solvent, and perform sand milling to obtain a nanoscale solid electrolyte slurry; S3. After solid-liquid separation of the nanoscale solid electrolyte slurry, supercritical CO2 drying is performed to obtain nanoscale solid electrolyte powder material with a water content of <2000ppm.

2. The method for preparing nanoscale chloride solid electrolyte according to claim 1, characterized in that, It also includes the following steps: S4. Using a mixed gas containing gaseous halohydrocarbons and inert gases as a gas source, the nano-solid electrolyte powder material is subjected to airflow pulverization to form a passivation layer on its surface, thereby obtaining the nano-scale chloride solid electrolyte.

3. The method for preparing nanoscale chloride solid electrolyte according to claim 1 or 2, characterized in that, In step S1, at least one of the following characteristics is satisfied: (1) The first polar solvent and the second polar solvent each independently include at least one of formamide, ethanol, glycerol, and propylene glycol; (2) The nonpolar solvent includes at least one of benzene, carbon tetrachloride, isooctane, toluene, dichloromethane, n-hexane, cyclohexane, heptane and liquid paraffin; (3) The first impurity removal includes: adding oxalic acid solution dropwise under stirring until the pH is 3-5, filtering to remove insoluble matter, and obtaining the first solution; wherein the oxalic acid solution includes an aqueous solution of oxalic acid and / or an ethanol solution of oxalic acid; (4) The second impurity removal includes: adding an alkaline solution dropwise under stirring until the pH is 9-10, separating the precipitate, collecting the filtrate, and obtaining the second solution; wherein the alkaline solution includes NaOH aqueous solution and / or ammonia water.

4. The method for preparing nanoscale chloride solid electrolyte according to claim 1 or 2, characterized in that, In step S2, when mixing the first solution and the second solution, the molar ratio of Li to metal M is 2-5:

1.

5. The method for preparing nanoscale chloride solid electrolyte according to claim 1 or 2, characterized in that, In step S2, the LiCl and the MCl n The total mass to the volume ratio of the nonpolar solvent is (1-100) g : (5-200) mL.

6. The method for preparing nanoscale chloride solid electrolyte according to claim 1 or 2, characterized in that, In step S2, the total volume ratio of the first polar solvent and the second polar solvent to the volume ratio of the nonpolar solvent is 1:1-2.

7. The method for preparing nanoscale chloride solid electrolyte according to claim 1 or 2, characterized in that, In step S2, the sand milling process takes 1-3 hours and the power of the sand milling process is 10-20 kW.

8. The method for preparing nanoscale chloride solid electrolyte according to claim 1 or 2, characterized in that, In step S3, the pressure of the supercritical CO2 drying is 10-15 MPa and the temperature is 170-230℃.

9. The method for preparing nanoscale chloride solid electrolyte according to claim 2, characterized in that, In step S4, at least one of the following characteristics is satisfied: (1) The gaseous halohydrocarbons include one or more of chloromethane, chloroethane, bromomethane, and bromoethane; (2) In the mixed gas, the volume concentration of the gaseous halohydrocarbon is 0.5%-50%; (3) During the airflow pulverization process, the pressure of the mixed gas is 0.5-2 MPa, the temperature of the mixed gas is 80-200℃, and the flow rate of the mixed gas is 1-10 m³ / s. 3 / min.

10. A nanoscale chloride solid electrolyte, characterized in that, It is prepared by the method of any one of claims 1-9 for the preparation of nanoscale chloride solid electrolyte.

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