A solid electrolyte and its preparation method and an all-solid-state battery

Abstract

This invention discloses a solid electrolyte, its preparation method, and an all-solid-state battery, belonging to the field of solid electrolyte technology. The preparation method involves mechanically grinding nano-inert oxides into a solid electrolyte raw material to obtain a solid electrolyte with a core-shell structure. From the inside out, it includes a core, an interface layer, and a shell. The core is the solid electrolyte matrix, the interface layer is a transition layer formed by the reaction of the solid electrolyte matrix and the nano-inert oxides, and the shell is the nano-inert oxide layer. This material combines the advantages of high moisture resistance and a wide electrochemical window of nano-inert oxides with the high ionic conductivity and excellent mechanical properties of solid electrolytes, achieving a significant improvement in the overall performance of the material through the synergistic effect between the components. This composite structure design not only solves the performance limitations of single-material systems but also achieves synergistic optimization of ionic conductivity, environmental adaptability, and electrochemical stability while ensuring material stability.

Description

Technical Field

[0001] This invention belongs to the field of solid electrolyte technology, and relates to a solid electrolyte, its preparation method and an all-solid-state battery. Background Technology

[0002] Traditional liquid lithium-ion batteries, due to their use of flammable organic electrolytes, pose safety hazards such as thermal runaway, combustion, and even explosion, and their energy density is approaching its theoretical limit. To overcome this technological bottleneck, developing next-generation battery technology that combines high safety and high energy density has become a global research hotspot. Solid-state batteries, with their revolutionary solid-state electrolyte design, not only fundamentally solve the safety problem but also exhibit higher energy density and longer cycle life, and are widely recognized as the future direction of battery technology.

[0003] Currently, mainstream solid-state electrolytes mainly fall into four categories: sulfides, halides, oxides, and polymers. Among them, sulfide solid-state electrolytes and halide solid-state electrolytes are considered the most promising material systems for industrialization due to their excellent ionic conductivity and good mechanical properties. However, both types of materials face severe environmental stability challenges: sulfide solid-state electrolytes readily react with moisture to release toxic gases, while halide solid-state electrolytes are extremely prone to hygroscopic decomposition in humid environments. Furthermore, their insufficient stability under high-voltage charging conditions also limits further improvements in their energy density. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a solid electrolyte, its preparation method and an all-solid-state battery to solve the problems of poor moisture resistance and high-voltage instability of solid electrolytes in the prior art.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A method for preparing a solid electrolyte, comprising the following steps: under inert gas protection, mixing solid electrolyte raw materials with nano-inert oxides in a set ratio to obtain a mixture; and mechanically grinding the mixture to obtain a solid electrolyte.

[0007] The solid electrolyte has a core-shell structure, comprising a core, an interface layer, and an outer shell from the inside out; the core is a solid electrolyte matrix, the interface layer is a transition layer formed by the reaction of the solid electrolyte matrix with nano-inert oxides, and the outer shell is a nano-inert oxide layer; the surface of the outer shell has defects, namely pits or holes; the solid electrolyte matrix is ​​a halide solid electrolyte or a sulfide solid electrolyte.

[0008] A further improvement of the present invention is that:

[0009] Preferably, the nano-inert oxide is any one or more of zirconium oxide, aluminum oxide, silicon dioxide, titanium dioxide, yttrium oxide, tantalum oxide, magnesium oxide, and lanthanum oxide.

[0010] Preferably, in the mixture, the mass percentage of the nano-inert oxide is 5wt%-50wt%, and the remainder is solid electrolyte raw material.

[0011] Preferably, the mechanical grinding speed is 300 rpm to 800 rpm, the mechanical grinding processing time is 1 h to 24 h, and the ball-to-material ratio is (5-60):1.

[0012] Preferably, the mixture is manually ground before being mechanically ground.

[0013] A solid electrolyte has a core-shell structure, comprising a core, an interface layer, and a shell from the inside out; the core is a solid electrolyte matrix, the interface layer is a transition layer formed by the reaction of the solid electrolyte matrix with nano-inert oxides, and the shell is a nano-inert oxide layer; the surface of the shell has defects, namely pits or holes; the solid electrolyte matrix is ​​a halide solid electrolyte or a sulfide solid electrolyte.

[0014] Preferably, the thickness of the outer shell is 6nm-80nm; the particle size of the solid electrolyte matrix is ​​500nm-1μm; and the thickness of the interface layer is 1nm-5nm.

[0015] Preferably, the nano-inert oxide layer is composed of particulate nano-inert oxides.

[0016] An all-solid-state battery includes a solid electrolyte as described in any one of the above claims, wherein the solid electrolyte has opposing positive and negative electrodes.

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

[0018] This invention discloses a method for preparing a solid electrolyte. The method involves mixing nano-inert oxides with solid electrolyte raw materials through mechanical grinding. During the mechanical grinding process, the solid electrolyte raw materials spontaneously and preferentially react to form a solid electrolyte matrix. Due to the poor reactivity of the nano-inert oxides, they do not preferentially react with the solid electrolyte raw materials. As mixing continues, the solid electrolyte matrix reacts and combines with a small amount of nano-inert oxides to form an intermediate transition layer. This allows the particulate nano-inert oxides to adhere to the surface of the solid electrolyte matrix, enhancing the connectivity between the two materials. Simultaneously, the mechanical grinding increases the surface defects of the nano-inert oxides, ensuring the ion transport capability of the solid electrolyte. Furthermore, this process eliminates the independent preparation step of intermediate materials, achieving one-step in-situ synthesis from raw materials to the final coated structure. This not only greatly simplifies the process and reduces energy consumption and time costs, but more importantly, it directly induces chemical reactions and coating on the broken, newly formed surface of the raw materials before oxidation or contamination. This results in a more uniform, denser, and more interfacially bonded outer shell, avoiding problems such as incomplete coating and poor interfacial compatibility caused by passivation of the pre-prepared material surface. This material cleverly combines the high moisture resistance and wide electrochemical window of the oxide component with the high ionic conductivity and excellent mechanical properties of the halide or sulfide component, achieving a significant improvement in overall material performance through the synergistic effect between the components. Simultaneously, due to mechanical grinding, the nano-inert oxide shell on the surface has many defects, avoiding the problem of excessively dense surface shell affecting the ion transport capacity of the solid electrolyte. This composite design not only solves the performance limitations of single-material systems but also achieves synergistic optimization of ionic conductivity, environmental adaptability, and electrochemical stability while ensuring material stability.

[0019] The second aspect of this invention discloses a solid-state electrolyte with a three-layer core-shell structure, comprising, from the inside out: a core halide solid-state electrolyte matrix or a sulfide solid-state electrolyte matrix, an intermediate transition layer, and an outermost nano-inert oxide layer. The outermost layer, due to its inertness and defect characteristics, can both inhibit direct contact between the core electrolyte and air and provide a migration channel for lithium ions; the intermediate interface layer is an oxygen-rich superion conductor, further enabling more efficient ion migration. This structure enables the material to possess both high ionic conductivity and excellent air stability, overcoming the problems of traditional sulfide and halide solid-state electrolytes being prone to reaction with moisture or hygroscopic decomposition; simultaneously, the outermost nano-inert oxide layer also endows the material with good high voltage stability, effectively widening the battery's operating voltage window. These characteristics collectively solve the key performance bottlenecks of existing solid-state electrolytes, providing important technical support for the development of high-energy-density, high-safety all-solid-state batteries. Attached Figure Description

[0020] Figure 1 SEM (scanning electron microscope) image and mapping (elemental distribution diagram) of the solid electrolyte material prepared in Example 1.

[0021] Among them, (a) is the SEM image of Example 1, (b) is the Zr element mapping image of Example 1, and (c) is the Al element mapping image of Example 1.

[0022] Figure 2 XRD patterns of solid electrolyte materials and Li2ZrCl6 materials provided in Examples 1-2 and Comparative Examples 1-2.

[0023] Figure 3 Impedance test results of the solid electrolyte material and Li2ZrCl6 material provided in Examples 1-2;

[0024] Figure 4 Statistical graphs of the ionic conductivity of solid electrolyte materials, Li2ZrCl6 materials, and Li2HfCl6 materials provided in Examples 1-8, Comparative Examples 1-2;

[0025] Figure 5 The image shows the first-cycle coulombic efficiency of the solid-state battery made from the solid electrolyte material of Example 2 in the 3V-4.5V charge-discharge range.

[0026] Figure 6 This is a long-cycle graph of the solid-state battery made of the solid electrolyte material of Example 2 in the 3V-4.5V charge-discharge range;

[0027] Figure 7 This is a statistical graph showing the ionic conductivity of the solid electrolyte material in Example 1 before and after exposure to air. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings:

[0029] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0030] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0031] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0032] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage.

[0033] The first aspect of this invention discloses a method for preparing a solid electrolyte, the method comprising the following steps: under the protection of an inert gas, mixing solid electrolyte raw materials with nano-inert oxides in a set ratio to obtain a mixture; and mechanically grinding the mixture to obtain a solid electrolyte.

[0034] The solid electrolyte has a core-shell structure, comprising a core, an interface layer, and an outer shell from the inside out. The core is the solid electrolyte matrix, and the interface layer is a transition layer formed by the reaction of the solid electrolyte matrix and nano-inert oxides. In the transition layer, oxygen and metal elements in some of the nano-inert oxides react with the solid electrolyte, ultimately forming an oxygen-rich superion conductor. This transition layer contains oxygen and, because it also contains metal elements that can act as conductors, reduces the crystallinity of the material and improves the lithium-ion transport capacity. The outer shell is also composed of nano-inert oxides, and its surface has defects, such as pits or holes.

[0035] The above method utilizes mechanochemical effects to induce a reaction between nano-inert oxides and an electrolyte matrix, forming a gradient transition layer. By controlling the grinding parameters, defective surface morphologies can be formed within the nano-inert oxide shell, thereby balancing ion transport and environmental stability. This shell structure can block water molecule penetration, enhancing the overall stability of the material. Simultaneously, the defective shell and the intermediate interface layer provide a transport path for lithium ions. This preparation method is simple to operate, suitable for large-scale production, and inexpensive.

[0036] Inert gas protection refers to the continuous introduction of a gas that does not chemically react with the raw materials during material processing. This can be achieved using argon or nitrogen to prevent oxidation or hydrolysis of the raw materials during the mixing stage. Mechanical grinding is a process that uses mechanical force to break and mix materials. This allows for the mutual reaction of solid electrolyte raw materials to form a solid electrolyte matrix, and also promotes interfacial reactions between the solid electrolyte matrix and nano-inert oxides. Surface defects refer to discontinuous areas in the outer shell layer, specifically pits or pores. These defects can be created by controlling the grinding intensity and time, providing channels for lithium-ion transport.

[0037] In some embodiments of the present invention, nano-inert oxides refer to metal oxides that do not undergo unintended chemical reactions with raw materials during the preparation of solid electrolytes. Specifically, materials with high chemical stability, such as zirconium oxide and aluminum oxide, can be used. Their function is to form a shell layer to isolate the electrolyte matrix from environmental moisture. However, with prolonged mechanical grinding, they can react with the solid electrolyte matrix in small amounts. Therefore, the nano-inert oxides include, but are not limited to, any one or more of zirconium oxide (ZrO2), aluminum oxide (Al2O3), silicon dioxide (SiO2), titanium dioxide (TiO2), yttrium oxide (Y2O3), tantalum oxide (Ta2O5), magnesium oxide (MgO), and lanthanum oxide (La2O3).

[0038] Among them, any one or more combinations refer to the selection of a single oxide or a mixture of multiple oxides according to actual process requirements. This can be achieved by adjusting the proportion of different oxide types, which can optimize the reactivity and mechanical strength of the interface layer.

[0039] In some embodiments of the present invention, the final solid electrolyte matrix is ​​a halide solid electrolyte or a sulfide solid electrolyte; wherein the halide solid electrolyte matrix includes, but is not limited to, Li3YCl6, Li3InCl6, and Li2Sc. 2 / 3 Cl4, Li2In x Sc 0.666-x Cl4(0.111≤ x ≤0.666), Li2ZrCl6, Li2HfCl6, Li 3-3y M 1+y Cl6 (M is Tb, Dy, Ho, Y, Er, or Tm) (0≤ y ≤1) or Li-NO-Cl (N is Ta, Nb, Hf or Zr); sulfide solid electrolyte matrix includes but is not limited to Li 10 GeP2S 12 Li 10 SnP2S 12Li6PS5Cl, Li3PS4 or Li7P3S 11 The solid electrolyte raw materials corresponding to the above solid electrolyte matrix are shown in Table 1 below:

[0040] Table 1 Solid electrolyte matrix and corresponding solid electrolyte raw materials

[0041]

[0042] It should be understood that, for any sulfide solid electrolyte or halide solid electrolyte, one or more nano-inert oxides are selected to complement the target electrolyte system in terms of chemical stability, interfacial reactivity and mechanical strength. This can improve the stability of the solid electrolyte in humid environments, prevent the sulfide solid electrolyte from releasing toxic gases or the halide solid electrolyte from absorbing moisture and decomposing, and at the same time reduce the resistance to lithium-ion transport by optimizing the composition of the interfacial layer.

[0043] In some embodiments of the present invention, the mass percentage of nano-inert oxides in the mixture is 5-50 wt%, with the remainder being solid electrolyte raw materials. If the mass percentage of nano-inert oxides in the entire mixture is too high, it can easily lead to an excessive amount of nano-inert oxides on the surface of the solid electrolyte matrix, affecting the ion transport capacity of the final solid electrolyte; if the content is too low, it is difficult to provide the corresponding protective effect.

[0044] In some embodiments of the present invention, the nano-inert oxide is in particulate form, and the particle size of the nano-inert oxide is 10nm-100nm. Particulate form refers to the discrete particle shape of the nano-inert oxide, which facilitates sufficient contact and uniform dispersion with the solid electrolyte raw material during mechanical grinding. A particle size of 10nm-100nm refers to the diameter range of the nano-inert oxide particles. Particles within this size range can form a tighter interfacial bond with the solid electrolyte raw material during mechanical grinding, avoiding the difficulty of the nano-inert oxide adhering to the solid electrolyte matrix due to excessively large particles.

[0045] In some embodiments of the present invention, the solid electrolyte raw material is in particulate form with a particle size of 500 nm to 1 μm. The particle size of the solid electrolyte raw material differs from that of the nano-inert oxide by more than an order of magnitude, ensuring that sufficient nano-inert oxide can adhere to the surface of the subsequently formed solid electrolyte matrix, thus guaranteeing that the nano-inert oxide can fully function.

[0046] During the grinding process, the particulate nano-inert oxides and the solid electrolyte matrix form an interfacial transition layer through surface atomic diffusion and local chemical reactions under high-speed collision and shear force. The pits or pores on the surface of the outer shell may be formed by the gaps between nanoparticles or by the shedding of particles due to local reactions. Nano-inert oxide particles in this size range can provide sufficient surface activity to promote interfacial reactions while avoiding the agglomeration problem caused by excessively small particles.

[0047] In some embodiments of the present invention, the mechanical grinding is any one of planetary ball milling, roller milling and sand milling.

[0048] Planetary ball milling refers to a pulverizing method where grinding balls collide and rub against materials using planetary-shaped grinding jars. This can be achieved using a ball mill with multiple grinding jars. Roller milling uses relatively rotating rollers to apply shearing force and pressure to materials. This can be achieved using roller mills with double or triple roller structures. Sand milling uses a high-speed rotating grinding disc to impact materials with grinding media. This can be achieved using a sand mill with zirconia beads or glass beads. It should be understood that the above three optional grinding processes allow for flexible adjustment of the pulverizing intensity and energy input based on the material characteristics.

[0049] Furthermore, the mechanical grinding speed is 300 rpm to 800 rpm, the grinding time is 1 hour to 24 hours, the ball-to-material ratio is (5-60):1, and the diameter of the grinding beads is 1 mm to 10 mm. Here, the mechanical grinding speed refers to the rotational speed of the rotor when the ball mill is running. Too low a speed will result in insufficient particle crushing efficiency, while too high a speed may cause localized overheating or excessive particle crushing. The mechanical grinding time refers to the residence time of the raw material in the grinding equipment. Too short a time will not allow for sufficient reaction between the solid electrolyte and the nano-inert oxide, while too long a time may damage the core-shell structure. The ball-to-material ratio refers to the mass ratio of the grinding media to the material. Too low a ball-to-material ratio will reduce grinding efficiency, while too high a ball-to-material ratio may cause excessive material crushing.

[0050] Preferably, the mechanical grinding speed is 200 rpm to 500 rpm, and the mechanical grinding time is 4 h to 16 h. The diameter of the grinding balls in the mechanical grinding is 2 mm to 5 mm; the ball-to-material ratio in the mechanical grinding is (20-40):1.

[0051] In some embodiments of the present invention, the mixture is manually ground and mixed before mechanical grinding to improve the mixing effect of subsequent mechanical grinding.

[0052] It should be understood that during the mixing process, the solid electrolyte raw materials are the reaction raw materials used in the preparation of halide solid electrolytes or sulfide solid electrolytes, and the mixing ratio is a stoichiometric ratio.

[0053] A second aspect of the present invention discloses a solid electrolyte having a core-shell structure, comprising a core, an interface layer, and a shell from the inside out; the core is a solid electrolyte matrix, the interface layer is a transition layer formed by the reaction of the solid electrolyte matrix with nano-inert oxides to generate products, and the shell is a nano-inert oxide layer; the surface of the shell has defects, namely pits or holes.

[0054] A core-shell structure refers to a multi-layered composite structure formed by encapsulating a solid electrolyte matrix with nano-inert oxides. Specifically, a mechanical grinding process can be used to achieve an interfacial reaction, thereby forming a transition layer between the core and the shell. This structure isolates the core from environmental erosion through the shell, while simultaneously enhancing structural stability through the interfacial layer.

[0055] The interface layer refers to the transition region formed by the chemical reaction between the solid electrolyte matrix and the nano-inert oxide under mechanical force. Specifically, the uniform formation of the interface layer can be achieved by controlling the grinding time and rotation speed. This layer alleviates the stress difference between the core and the shell, preventing interlayer delamination. Defects on the shell surface refer to the discontinuous structure present in the nano-inert oxide layer. These can be created by adjusting the grinding media size or ball-to-particle ratio to form pits or pores. These defect structures increase the contact area between the solid electrolyte and the electrode material, while also providing channels for ion transport. This invention achieves chemical bonding between materials through the interface layer generated by mechanical grinding, significantly improving structural stability. Furthermore, if the shell of the nano-inert oxide is a dense structure, it may hinder ion migration; however, this solution optimizes ion transport efficiency while maintaining the protective effect by introducing controllable defect structures.

[0056] In some embodiments of the present invention, the thickness of the outer shell is 6nm-85nm; the particle size of the solid electrolyte matrix is ​​500nm-1μm; and the thickness of the interface layer is 1nm-5nm.

[0057] In some embodiments of the present invention, the nano-inert oxide layer is composed of particulate nano-inert oxides. The particulate nano-inert oxides and the solid electrolyte matrix form a core-shell structure through mechanical action. The surface of the outer shell layer, naturally stacked between the particles, produces irregular pores or pits. This porous structure allows lithium ions to be transported through the interface layer while effectively blocking the intrusion of external moisture. During the grinding process, the particulate nano-inert oxides partially embed into the surface of the electrolyte matrix, forming a transitional interface layer with chemical bonds after the reaction.

[0058] The present invention also discloses an all-solid-state battery based on the above-mentioned solid electrolyte, wherein the solid electrolyte has a positive electrode and a negative electrode respectively, wherein the positive electrode material is a commonly available lithium cobalt oxide material, lithium iron phosphate material or nickel cobalt manganese ternary positive electrode material, the negative electrode material is lithium metal and its alloy metal negative electrode, and the all-solid-state battery is an all-solid-state lithium battery.

[0059] This invention employs a mechanical grinding method to composite nano-inert oxide materials with halide or sulfide solid electrolyte materials, preparing a novel solid electrolyte material. This material possesses a three-layer core-shell structure, combining the high moisture resistance and wide electrochemical window of the nano-inert oxide component with the high ionic conductivity and excellent mechanical properties of the halide or sulfide solid electrolyte. Through the synergistic effect between the components, a significant improvement in the overall performance of the material is achieved. This composite design not only overcomes the performance limitations of single-material systems but also achieves synergistic optimization of ionic conductivity, environmental adaptability, and electrochemical stability while ensuring material stability.

[0060] The present invention will be further explained and illustrated below through specific embodiments. It should be understood that the thickness measurements in all the following embodiments are taken under microscopic conditions, so the dimensions cannot be obtained with precise data and are all approximate values.

[0061] Comparative Example 1

[0062] A solid electrolyte material, the components and their mass percentages are as follows:

[0063] The content of Li2ZrCl is 685%, and the particle size is approximately 1 μm.

[0064] SiO2 15%, with a particle size of approximately 100 nm.

[0065] The solid electrolyte Li2ZrCl6 and the nano-inert oxide raw material SiO2 were poured into an agate mortar and ground by hand for 10 minutes. During the grinding process, continuous grinding was required to ensure uniformity and obtain powder.

[0066] The obtained powder was poured into a zirconia ball mill jar and milled using a high-energy ball mill with 8mm diameter grinding beads, a ball-to-powder ratio of 20:1, a milling speed of 350 rpm, and for 10 hours. After milling, the ball mill jar was returned to the glove box, and the obtained powder was removed, yielding the solid electrolyte material in powder form with a particle size of approximately 0.8μm.

[0067] Comparative Example 2

[0068] A solid electrolyte material, the components and their mass percentages are as follows:

[0069] The content of Li2ZrCl is 685%, and the particle size is approximately 1 μm.

[0070] TiO2 15%, with a particle size of approximately 100 nm.

[0071] The solid electrolyte Li2ZrCl6 and the nano-inert oxide raw material TiO2 were poured into an agate mortar and ground by hand for 10 minutes. During the grinding process, the grinding should be continuous and the uniformity of grinding should be ensured.

[0072] The obtained powder was poured into a zirconia ball mill jar and milled using a high-energy ball mill with 8mm diameter grinding beads, a ball-to-powder ratio of 20:1, a milling speed of 350 rpm, and for 10 hours. After milling, the ball mill jar was returned to the glove box, and the obtained powder was removed, yielding the solid electrolyte material in powder form with a particle size of approximately 0.8μm.

[0073] Example 1

[0074] A solid electrolyte material is prepared by first weighing the raw materials LiCl and ZrCl4 for Li2ZrCl6 in a molar ratio of LiCl:ZrCl4 = 2:1. Then, the corresponding SiO2 particles with a particle size of approximately 100 nm are weighed in a mass ratio of (LiCl + ZrCl4):SiO2 = 0.85:0.15.

[0075] Pour the above raw materials into an agate mortar and grind them by hand for 10 minutes. During the grinding process, you need to continue grinding and ensure that the grinding is uniform.

[0076] The obtained powder was poured into a zirconia ball mill jar and milled using a high-energy ball mill with 8mm diameter grinding beads, a ball-to-powder ratio of 20:1, a milling speed of 500 rpm, and for 10 hours. After milling, the ball mill jar was returned to the glove box, and the obtained powder was removed to obtain the solid electrolyte material. The core diameter was approximately 600nm, the interface layer thickness was approximately 3nm, and the outer shell thickness was approximately 85nm.

[0077] Example 2

[0078] A solid electrolyte material is prepared by first weighing the raw materials LiCl and ZrCl4 for Li2ZrCl6 in a molar ratio of LiCl:ZrCl4=2:1, and then weighing the corresponding TiO2 in a mass ratio of (LiCl+ZrCl4):TiO2=0.85:0.15, with the TiO2 particle size being approximately 100nm.

[0079] Pour the above raw materials into an agate mortar and grind them by hand for 10 minutes. During the grinding process, you need to continue grinding and ensure that the grinding is uniform.

[0080] The obtained powder was poured into a zirconia ball mill jar and milled using a high-energy ball mill with 8mm diameter grinding beads, a ball-to-powder ratio of 20:1, a milling speed of 500 rpm, and for 10 hours. After milling, the ball mill jar was returned to the glove box, and the obtained powder was removed to obtain the solid electrolyte material. The core diameter was approximately 600nm, the interface layer thickness was approximately 2nm, and the outer shell thickness was approximately 80nm.

[0081] Example 3

[0082] A solid electrolyte material is prepared by first weighing the raw materials LiCl and ZrCl4 for Li2ZrCl6 in a molar ratio of LiCl:ZrCl4 = 2:1. Then, the corresponding ZrO2 is weighed in a mass ratio of (LiCl + ZrCl4):ZrO2 = 0.75:0.25, wherein the particle size of ZrO2 is 100 nm.

[0083] Pour the above raw materials into an agate mortar and grind them by hand for 10 minutes. During the grinding process, you need to continue grinding and ensure that the grinding is uniform.

[0084] The obtained powder was poured into a zirconia ball mill jar and milled using a high-energy ball mill with 10mm diameter grinding beads, a ball-to-powder ratio of 20:1, a milling speed of 500 rpm, and for 5 hours. After milling, the ball mill jar was returned to the glove box, and the obtained powder was removed to obtain the solid electrolyte material. In the final solid electrolyte material, the core diameter is approximately 800nm, the interface layer thickness is approximately 1nm, and the outer shell thickness is approximately 80nm.

[0085] Example 4

[0086] A solid electrolyte material is prepared by first weighing the raw materials LiCl and ZrCl4 for Li2ZrCl6 in a molar ratio of LiCl:ZrCl4 = 2:1. Then, the corresponding Al2O3 is weighed in a mass ratio of (LiCl + ZrCl4):Al2O3 = 0.65:0.35, wherein the particle size of Al2O3 is 10 nm.

[0087] Pour the above raw materials into an agate mortar and grind them by hand for 10 minutes. During the grinding process, you need to continue grinding and ensure that the grinding is uniform.

[0088] The obtained powder was poured into a zirconia ball mill jar and milled using a high-energy ball mill. The ball diameter was 1 mm, the ball-to-powder ratio was 20:1, the milling speed was 300 rpm, and the milling time was 24 hours. After milling, the ball mill jar was returned to the glove box, and the obtained powder was removed to obtain the solid electrolyte material. In the final solid electrolyte material, the core diameter was approximately 700 nm, the interface layer thickness was approximately 1.5 nm, and the outer shell thickness was approximately 6 nm.

[0089] Example 5

[0090] A solid electrolyte material is prepared by first weighing the raw materials LiCl and HfCl4 for Li2HfCl6 in a molar ratio of LiCl:HfCl4 = 2:1. Then, the corresponding Y2O3 particles with a particle size of 100 nm are weighed in a mass ratio of (LiCl+HfCl4):Y2O3 = 0.95:0.05.

[0091] Pour the above raw materials into an agate mortar and grind them by hand for 10 minutes. During the grinding process, you need to continue grinding and ensure that the grinding is uniform.

[0092] The obtained powder was poured into a zirconia ball mill jar and milled using a high-energy ball mill with 5 mm diameter grinding beads, a ball-to-powder ratio of 20:1, a milling speed of 600 rpm, and for 15 hours. After milling, the ball mill jar was returned to the glove box, and the obtained powder was removed to obtain the solid electrolyte material. In the final solid electrolyte material, the core diameter is approximately 900 nm, the interface layer thickness is approximately 1 nm, and the outer shell thickness is approximately 70 nm.

[0093] Example 6

[0094] A solid electrolyte material is prepared by first weighing the raw materials LiCl and HfCl4 for Li2HfCl6 in a molar ratio of LiCl:HfCl4 = 2:1. Then, the corresponding Ta2O5 particles are weighed in a mass ratio of (LiCl + HfCl4):Ta2O5 = 0.50:0.50, wherein the particle size of Ta2O5 is 50 nm.

[0095] Pour the above raw materials into an agate mortar and grind them by hand for 10 minutes. During the grinding process, you need to continue grinding and ensure that the grinding is uniform.

[0096] The obtained powder was poured into a zirconia ball mill jar and milled using a high-energy ball mill with 8mm diameter grinding beads, a ball-to-powder ratio of 10:1, a milling speed of 800 rpm, and for 1 hour. After milling, the ball mill jar was returned to the glove box, and the obtained powder was removed to obtain the solid electrolyte material. In the final solid electrolyte material, the core diameter is approximately 1μm, the interface layer thickness is approximately 2nm, and the outer shell thickness is approximately 40nm.

[0097] Example 7

[0098] A solid electrolyte material is prepared by first weighing the raw materials LiCl and HfCl4 for Li2HfCl6 in a molar ratio of LiCl:HfCl4 = 2:1. Then, the corresponding MgO is weighed in a mass ratio of (LiCl + HfCl4):MgO = 0.60:0.40, wherein the particle size of MgO is 50 nm.

[0099] Pour the above raw materials into an agate mortar and grind them by hand for 10 minutes. During the grinding process, you need to continue grinding and ensure that the grinding is uniform.

[0100] The obtained powder was poured into a zirconia ball mill jar and milled using a high-energy ball mill. The ball diameter was 8 mm, the ball-to-powder ratio was 5:1, the milling speed was 700 rpm, and the milling time was 8 hours. After milling, the ball mill jar was returned to the glove box, and the obtained powder was removed to obtain the solid electrolyte material. In the final solid electrolyte material, the core diameter is approximately 500 nm, the interface layer thickness is approximately 3 nm, and the outer shell thickness is approximately 30 nm.

[0101] Example 8

[0102] A solid electrolyte material is prepared by first weighing Li₂ZrCl₆ raw material at a molar ratio of LiCl:ZrCl₄ = 2:1. Then, La₂O₃ is weighed at a mass ratio of (LiCl + ZrCl₄):La₂O₃ = 0.85:0.15, wherein the particle size of La₂O₃ is 100 nm.

[0103] Pour the above raw materials into an agate mortar and grind them by hand for 10 minutes. During the grinding process, you need to continue grinding and ensure that the grinding is uniform.

[0104] The obtained powder was poured into a zirconia ball mill jar and milled using a high-energy ball mill. The ball diameter was 8 mm, the ball-to-powder ratio was 60:1, the milling speed was 300 rpm, and the milling time was 18 hours. After milling, the ball mill jar was returned to the glove box, and the obtained powder was removed to obtain the solid electrolyte material. In the final solid electrolyte material, the core diameter is approximately 800 nm, the interface layer thickness is approximately 5 nm, and the outer shell thickness is approximately 70 nm.

[0105] Test Example 1

[0106] The solid electrolyte material prepared according to Example 1 is described in [reference]. Figure 1 The image shows the SEM image of the powder and the corresponding mapping image obtained in this embodiment. It can be seen from the image that the Al element is uniformly distributed in the solid electrolyte, indicating that Al2O3 is uniformly coated on the surface of the solid electrolyte.

[0107] Test Example 2

[0108] This test example performs X-ray diffraction tests on the solid electrolyte materials and Li2ZrCl6 materials provided in Examples 1, 2, Comparative Examples 1 and 2 above, with diffraction angles ranging from 10° to 90°. The results are as follows: Figure 2 As shown, it can be observed that the solid electrolyte material provided by this invention has lower crystallinity compared to Li2ZrCl6 material. Compared to the comparative example, the crystallinity of the sample synthesized by direct ball milling of raw materials in the embodiment is further reduced.

[0109] Test Example 3

[0110] This test example performs impedance tests on Examples 1 and 2, as well as on the Li2ZrCl6 material. The Li2ZrCl6 material itself does not contain any nano-inert oxides. R in the figure... grain boundary Representing grain boundary impedance, the results are as follows: Figure 3 As shown in the figure, the addition of Al2O3 significantly reduces grain boundary impedance and improves ion conductivity. Therefore, it can be seen that introducing nano-inert oxides during the synthesis stage of the solid electrolyte raw materials allows them to participate in the entire reaction process. Thanks to their high chemical inertness, these nano-inert oxides not only do not hinder the formation of the target electrolyte but also undergo a slight in-situ reaction, thereby generating an interface layer at the electrolyte particle interface that effectively promotes lithium-ion transport. This interface layer significantly reduces grain boundary impedance, thereby significantly improving the interfacial transport rate of lithium ions. The in-situ reaction generation mechanism relied upon in this invention is fundamentally different from conventional techniques that use nano-inert oxides as an external coating layer, the latter of which introduces a high-impedance interface due to physical adhesion, severely hindering ion transport.

[0111] Test Example 4

[0112] This test example performs electrochemical impedance spectroscopy on the solid electrolyte materials provided in Examples 1-8 and Comparative Examples 1-2, as well as Li2ZrCl6 and Li2HfCl6 materials, and calculates their ionic conductivity. The results are as follows: Figure 4 As shown. By Figure 4 The results show that the ionic conductivity of the solid electrolyte materials provided in Examples 1-8 and Comparative Examples 1-2 is higher than that of the Li2ZrCl6 material, with Example 1 showing the highest ionic conductivity of 1.21 mS·cm. -1 .

[0113] Test Example 5

[0114] This test used the solid electrolyte material prepared in Example 2 to assemble a solid-state battery, and conducted electrochemical performance tests using the Blue Electricity testing system under a constant temperature of 25°C. Specific test parameters were set as follows: charge / discharge voltage window 3 V - 4.5 V (vs. Li). + (Li), initial cycle rate 0.1C, followed by 1C long-term cycling. The compatibility of the solid electrolyte and cathode was assessed by testing the coulombic efficiency of the first cycle, and the long-term cycling stability of the battery under high voltage conditions was evaluated by continuous cycling tests. The specific steps are as follows:

[0115] 1) Take a certain amount of the solid electrolyte material provided in Example 2 and compress it under a pressure of 220 MPa to obtain a solid electrolyte sheet.

[0116] 2) Mix and grind the positive electrode LiCoO2 and solid electrolyte powder at a mass ratio of 7:3. Take 10mg as the positive electrode layer material and place it on one side of the solid electrolyte sheet prepared in step 1), and apply a pressure of 220MPa.

[0117] 3) Add Li6PS5Cl material to the other side of the solid electrolyte sheet prepared in step 1) and apply a pressure of 220MPa.

[0118] 4) Lithium foil and steel sheet are added sequentially to the Li6PS5Cl side. The mixture is then pressed at 220 MPa to obtain an all-solid-state battery.

[0119] 5) Perform 1C charge and discharge cycles on the all-solid-state batteries obtained in step 4), with a voltage range of 3V-4.5V vs. Li. + / Li.

[0120] The first-cycle coulombic efficiency of the solid-state battery obtained in Test Example 5 is as follows: Figure 5 As shown in the figure, 1st is short for first, representing the first cycle. It can be seen from the figure that the coulombic efficiency of the solid battery in the first cycle is 98.85% in the high voltage charging range of 3V-4.5V, which shows the good compatibility between the solid electrolyte and the cathode material of Example 2.

[0121] The long-cycle performance of the solid-state battery obtained in Test Example 5 is as follows: Figure 6 As shown, after 200 cycles, the specific capacity is still 126.2 mAh / g, and the capacity retention rate is 85.3%, indicating that the solid-state battery assembled with the solid electrolyte in Example 2 has very good long-cycle performance under high voltage.

[0122] Test Example 6

[0123] The solid electrolyte material of Example 1 was placed in air with a relative humidity of 3% and left to stand for 12 hours. Its electrochemical impedance spectroscopy was then measured to obtain the ionic conductivity of the exposed sample, which was compared with the ionic conductivity of the unexposed sample. Figure 7 As shown. From Figure 7 As can be seen, after the solid electrolyte material of Example 1 was exposed to air with a relative humidity of 3%, the retention rate of ionic conductivity was as high as 80.2%, demonstrating the excellent moisture resistance of the solid electrolyte of Example 1.

[0124] In summary, this invention successfully prepared a novel solid-state electrolyte material. This material cleverly combines the high moisture resistance and wide electrochemical window of nano-inert oxide components with the high ionic conductivity and excellent mechanical properties of halide or sulfide solid-state electrolytes, achieving a significant improvement in the overall performance of the material through the synergistic effect between the components.

[0125] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of preparing a solid-state electrolyte, characterized by, The preparation method comprises the following steps: mixing solid electrolyte raw materials and nano-inert oxide in a set proportion under inert gas protection to obtain a mixture; and mechanically grinding the mixture, so that the solid electrolyte raw materials spontaneously and preferentially react to generate a solid electrolyte matrix, the solid electrolyte matrix reacts with a small amount of nano-inert oxide to generate an intermediate transition layer. The nano-inert oxide is any one or several of zirconium oxide, aluminum oxide, silicon dioxide, titanium dioxide, yttrium oxide, tantalum oxide, magnesium oxide and lanthanum oxide. The solid electrolyte has a core-shell structure, comprising an inner core, an interface layer and an outer shell from inside to outside; the inner core is the solid electrolyte matrix, the interface layer is the transition layer generated by the reaction of the solid electrolyte matrix and the nano-inert oxide, and the outer shell is the nano-inert oxide layer; the surface of the outer shell has defects, the defects are pits or holes; and the solid electrolyte matrix is a halide solid electrolyte. The thickness of the interface layer is 1 nm-5 nm.

2. The method of claim 1, wherein the solid-state electrolyte is prepared by a process comprising: In the mixture, the mass fraction of the nano-inert oxide is 5wt%-50wt%, and the remainder is the solid electrolyte raw materials. ​ 3. The method of claim 1, wherein the solid-state electrolyte is prepared by a process comprising: The rotation speed of the mechanical grinding is 300 revolutions / minute-800 revolutions / minute, the processing time of the mechanical grinding is 1 h-24 h, and the ball-to-material ratio is (5-60):

1. ​ 4. The method of claim 1, wherein the solid-state electrolyte is prepared by a process comprising: The mixture is mixed by manual grinding before being mechanically ground. ​ 5. A solid-state electrolyte obtained by the production method according to claim 1, characterized in that, The solid electrolyte has a core-shell structure, comprising an inner core, an interface layer and an outer shell from inside to outside; the inner core is the solid electrolyte matrix, the interface layer is the transition layer generated by the reaction of the solid electrolyte matrix and the nano-inert oxide, and the outer shell is the nano-inert oxide layer; the surface of the outer shell has defects, the defects are pits or holes; and the solid electrolyte matrix is a halide solid electrolyte. The nano-inert oxide layer is composed of particulate nano-inert oxide; the nano-inert oxide is any one or several of zirconium oxide, aluminum oxide, silicon dioxide, titanium dioxide, yttrium oxide, tantalum oxide, magnesium oxide and lanthanum oxide; and the thickness of the interface layer is 1 nm-5 nm.

6. The solid state electrolyte of claim 5, wherein, The thickness of the outer shell is 6 nm-80 nm, and the particle size of the solid electrolyte matrix is 500 nm-1 μm.

7. An all-solid battery, characterized by, The solid electrolyte comprises the solid electrolyte of claim 5, and the solid electrolyte is provided with opposite positive and negative electrodes.

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