Solid-state electrolyte, and preparation method therefor and use thereof

Abstract

The present application provides a solid-state electrolyte, and a preparation method therefor and a use thereof. The chemical composition of the solid-state electrolyte is LixGayAaDbOc, wherein 0.5≤x≤2.0, 0.1≤y≤0.5, 0.1≤a≤1, 3.5≤b≤5, and 0.25≤c≤1.5; A comprises four or more of Y, In, Al, La, Ce, Ho, Zr, Ta, and Nb; and D comprises one or more of F, Cl, and Br. In an X-ray diffraction (XRD) pattern, diffraction peaks at 2θ in the ranges of 24°-26°, 27°-29°, 42°-46°, and 49°-54° are comprised. In the solid-state electrolyte provided in the present application, by defining the chemical composition and the 2θ of the diffraction peaks in XRD, the degree of disorder of the solid-state electrolyte can be increased, the ionic conductivity can be increased, and the flexibility of the solid-state electrolyte can also be improved, thereby improving the specific capacity and cycle performance of a battery.

Description

A solid electrolyte, its preparation method and application

[0001] This application claims priority to Chinese Patent Application No. 202510228372.8, filed on February 27, 2025, entitled "A Solid Electrolyte and Its Preparation Method and Application", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application belongs to the field of battery technology, and in particular relates to a solid electrolyte, its preparation method and application. Background Technology

[0003] Solid-state batteries, with their advantages of high energy density and strong safety, are considered strong contenders for next-generation lithium-ion batteries. The core component of a solid-state battery is the solid electrolyte, which serves as both a lithium-ion transporter and a separator. Currently, commonly used solid-state electrolytes are divided into organic and inorganic types. However, due to the low ionic conductivity of organic solid-state electrolytes, they are difficult to meet the requirements of high-energy-density batteries. Emerging inorganic halide solid-state electrolytes, with their wide electrochemical window and good processability, are gradually becoming one of the mainstream electrolytes.

[0004] However, existing inorganic solid electrolytes still suffer from low ionic conductivity and poor solid-solid interface contact with electrode materials, resulting in low battery specific capacity and poor cycle performance. Summary of the Invention

[0005] The main objective of this application is to provide a solid electrolyte with high ionic conductivity and good solid-solid interface contact with electrode materials. When applied to batteries, it can improve the specific capacity and cycle performance of the batteries.

[0006] This application also provides a method for preparing a solid electrolyte, which can prepare the above-mentioned solid electrolyte and is simple and low in cost.

[0007] This application also provides a positive electrode sheet including the above-mentioned solid electrolyte. Therefore, when this positive electrode sheet is applied to a battery, it can improve the battery's specific capacity and cycle performance.

[0008] This application also provides a battery comprising the above-described solid electrolyte, thus the battery has excellent specific capacity and cycle performance.

[0009] Firstly, this application provides a solid electrolyte, wherein the chemical composition of the solid electrolyte is Li x Ga y A a D b O cWherein, 0.5≤x≤2.0, 0.1≤y≤0.5, 0.1≤a≤1, 3.5≤b≤5, 0.25≤c≤1.5; A includes four or more of Y, In, Al, La, Ce, Ho, Zr, Ta, and Nb, and D includes one or more of F, Cl, and Br;

[0010] In the X-ray diffraction pattern, there are diffraction peaks of 2θ located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

[0011] In the solid electrolyte described above, A includes the element Y, and the molar ratio of the element Y to the element Ga is 1:(0.45-1.5).

[0012] In the solid electrolyte described above, D includes two or more of F, Cl, and Br.

[0013] In the solid electrolyte described above, D includes at least F.

[0014] In the solid electrolyte described above, the molar ratio of any one of the metal elements in A to Ga is (0.8-1.2):1.

[0015] The solid electrolyte described above is in the form of clay.

[0016] The solid electrolyte described above has an ionic conductivity greater than 1 mS / cm.

[0017] As described above, the solid electrolyte exhibits a full width at half maximum (FWHM) of the widest diffraction peak in its X-ray diffraction pattern that is greater than or equal to 1.35°.

[0018] The solid electrolyte as described above has a Young's modulus of less than or equal to 3 GPa.

[0019] Secondly, this application provides a method for preparing the solid electrolyte as described above, comprising the following steps:

[0020] 1) A mixture is obtained by grinding a raw material system including lithium halide, lithium oxide, gallium halide, and halides containing element A;

[0021] 2) Under an inert atmosphere, the mixture is subjected to ball milling and heat treatment in sequence to obtain the solid electrolyte.

[0022] In the preparation method of the solid electrolyte as described above, the grinding process takes 5-30 minutes.

[0023] And / or, the ball milling process is performed at a speed of 400 rpm to 600 rpm for 0.5 h to 4 h, with a ball-to-material ratio of (10-40):1;

[0024] And / or, the heat treatment temperature is 150℃-250℃, and the time is 1h-4h;

[0025] And / or, the halide containing element A includes yttrium halide, and the molar ratio of yttrium halide to gallium halide is 1:(0.45-1.5).

[0026] Thirdly, this application provides a positive electrode sheet, comprising the solid electrolyte as described above or the solid electrolyte prepared by the method described above.

[0027] Fourthly, this application provides a battery comprising a solid electrolyte as described above, a solid electrolyte prepared by the method described above, or a positive electrode as described above.

[0028] The solid electrolyte provided in this application, through the limitation of its chemical composition and the 2θ diffraction peak in XRD, can improve the disorder of the solid electrolyte, increase its ionic conductivity, and enhance its flexibility. This allows the solid electrolyte to form a stable interface layer when in contact with electrode materials, reducing interfacial reactions and the formation of byproducts. This favorable interfacial contact facilitates efficient ion transport, thereby improving the battery's specific capacity and cycle performance. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the accompanying drawings used in the description of the embodiments of this application or related technologies are briefly introduced below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 is the XRD pattern of the solid electrolyte of Example 1 and Comparative Example 1 of this application;

[0031] Figure 2 is the XRD pattern of the solid electrolyte of Example 2 of this application;

[0032] Figure 3 is the XRD pattern of the solid electrolyte of Example 3 of this application;

[0033] Figure 4 is the XRD pattern of the solid electrolyte of Comparative Example 2 of this application;

[0034] Figure 5 is the XRD pattern of the solid electrolyte of Comparative Example 3 of this application;

[0035] Figure 6 is the XRD pattern of the solid electrolyte of Comparative Example 4 of this application;

[0036] Figure 7 is the XRD pattern of the solid electrolyte of Comparative Example 5 of this application;

[0037] Figure 8a shows the morphology of the solid electrolyte of Example 1 of this application, and b shows the morphology of the solid electrolyte of Comparative Example 1 of this application. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] Solid-state batteries, as the forefront of next-generation lithium-ion battery technology, hinge on the performance optimization of solid-state electrolytes. Solid-state electrolytes not only need to act as the medium for lithium-ion transport within the battery but also function as a separator to ensure battery safety and stability. While traditional liquid electrolytes possess high ionic conductivity, their flammability and leakage risk limit their application in high-energy-density batteries. In contrast, solid-state electrolytes, due to their non-flammability and high-temperature resistance, have become a hot research topic.

[0040] Among solid-state electrolytes, inorganic solid-state electrolytes, especially inorganic halide solid-state electrolytes, have gradually attracted attention due to their wide electrochemical window and excellent processability. However, existing inorganic solid-state electrolytes still face some technical challenges. First, their ionic conductivity is relatively low, making it difficult to meet the requirements of high power density applications. Second, inorganic halide solid-state electrolytes themselves possess certain mechanical properties, leading to poor solid-solid interface contact between the solid-state electrolyte and electrode materials during solid-state battery assembly, resulting in increased interfacial impedance. This interface problem not only limits the effective transport of lithium ions but also affects the battery's specific capacity and cycle performance. Therefore, improving the ionic conductivity of inorganic solid-state electrolytes and enhancing their interfacial contact with electrode materials has become a key bottleneck in current technological development.

[0041] The applicant of this application has found through research that if the structure-property relationship of the material itself can be improved to a certain extent, while maintaining a high ionic conductivity, the performance degradation of the battery caused by interface problems will be greatly reduced.

[0042] Based on this, firstly, this application provides a solid electrolyte, the chemical composition of which is Li x Ga y A a D b Oc Wherein, 0.5≤x≤2.0, 0.1≤y≤0.5, 0.1≤a≤1, 3.5≤b≤5, 0.25≤c≤1.5; A includes four or more of Y, In, Al, La, Ce, Ho, Zr, Ta, and Nb, and D includes one or more of F, Cl, and Br; in the X-ray diffraction pattern, it includes diffraction peaks of 2θ located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

[0043] For example, x can be a range consisting of 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, or any two of these values; y can be a range consisting of 0.1, 0.2, 0.3, 0.4, 0.5, or any two of these values; a can be a range consisting of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1... b can be a range consisting of 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5 or any two of them; c can be a range consisting of 0.25, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 or any two of them.

[0044] The solid electrolyte provided in this application has high ionic conductivity and good solid-solid interface contact with the electrode material. When applied to batteries, it can improve the specific capacity and cycle performance. This is because the Li content provides sufficient lithium-ion concentration, which helps to improve ionic conductivity. A includes at least four metal elements, meaning the solid electrolyte contains at least five metal elements, making it a high-entropy halide solid electrolyte. The high-entropy effect can lead to an increase in disorder in the crystal lattice, thereby creating more migration channels and defects, which helps to improve the mobility of lithium ions and the overall ionic conductivity. In addition, element D includes one or more of F, Cl, and Br. Ga element has a synergistic effect with monovalent halide anions. When the two coexist, they significantly increase the proportion of amorphous state in the solid electrolyte by changing the crystal structure type, thereby increasing the flexibility of the solid electrolyte and changing its physical characteristics from powder to clay-like. Oxygen ions are divalent anions, with a structure completely different from halide anions. Introducing heterovalent elements at the anion end enhances the disorder in the structure, increases the defect sites and carrier concentration in the crystal structure, and significantly improves lithium-ion conductivity. While improving the flexibility of inorganic materials, it still maintains a high ionic conductivity.

[0045] Meanwhile, the solid electrolyte of this application exhibits significant peak broadening in its X-ray diffraction (XRD) pattern, including 2θ peaks at 24°-26°, 27°-29°, 42°-46°, and 49°-54°, ​​indicating a high proportion of amorphous matter in the solid electrolyte. This high proportion of amorphous matter gives the solid electrolyte clay-like or film-like characteristics; compared to a purely hard powder, it becomes softer, exhibiting flexibility. This facilitates the formation of a tight contact at the solid-solid interface, reduces interfacial impedance, improves interfacial stability, and promotes efficient lithium-ion transport, thereby enhancing the battery's specific capacity and cycle performance.

[0046] Therefore, the solid electrolyte provided in this application, by limiting its chemical composition and the 2θ diffraction peak in XRD, can improve the disorder of the solid electrolyte, increase its ionic conductivity, and also increase its flexibility. This allows the solid electrolyte to form a stable interface layer when in contact with electrode materials, reducing interfacial reactions and the formation of byproducts. This good interfacial contact facilitates efficient ion transport, thereby improving the battery's specific capacity and cycle performance.

[0047] In some embodiments of this application, A includes element Y, and the molar ratio of element Y to element Ga is 1:(0.45-1.5). For example, it can be a range consisting of 1:0.45, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, or any two of these.

[0048] In this application, Y has a large ionic radius, providing a stable framework structure. Ga, with its smaller ionic radius and diverse coordination environments, enhances the overall stability of the material, resulting in a stable crystal structure for the solid electrolyte. By adjusting the molar ratio of Y to Ga, the defect and channel structure in the lattice can be optimized, thereby improving lithium-ion mobility. An appropriate Ga content can promote rapid ion migration within the lattice, increasing overall ionic conductivity. Furthermore, it also enhances the flexibility of the solid electrolyte, significantly improving poor solid-solid contact.

[0049] In some embodiments of this application, D includes two or more of F, Cl and Br.

[0050] In this application, when D includes two or more of F, Cl and Br, the lithium ion mobility can be improved by introducing lattice defects and diversified migration channels due to the high electronegativity and different ionic radii of halogen elements, thereby improving the ionic conductivity of the solid electrolyte and thus improving the specific capacity and cycle performance of the battery.

[0051] In some embodiments of this application, D includes at least F.

[0052] It is understandable that phosphorus ions (F) have a small ionic radius and high electronegativity, which helps to form effective lithium-ion migration channels in solid-state electrolytes. The introduction of F can increase defects and vacancies in the crystal lattice, promoting rapid lithium-ion migration and thus improving the ionic conductivity of the solid-state electrolyte. In addition, the introduction of F can form a stable interface layer between the solid-state electrolyte and the electrode material, reducing interface impedance and improving interface stability, which is beneficial to improving the cycle performance and overall efficiency of the battery.

[0053] In some embodiments of this application, the molar ratio of any metal element in A to Ga is (0.8-1.2):1, for example, it can be a range of 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1 or any two of them.

[0054] In this application, by setting the molar ratio of each metal element in A to Ga to (0.8-1.2):1, a uniform crystal structure can be formed, which helps to reduce stress concentration and defects in the crystal lattice, thereby improving the stability of the solid electrolyte. Furthermore, the uniform distribution of metal elements can form more regular ion channels, promoting lithium-ion migration and improving the ionic conductivity of the material. In addition, the uniform distribution of metal elements can improve the mechanical properties of the electrolyte, enabling it to better resist volume changes and mechanical stress during charging and discharging, thus improving the cycle life of the battery. It can also improve the interfacial contact between the solid electrolyte and the electrode material, forming a stable interfacial layer, reducing interfacial impedance, and improving interfacial stability.

[0055] In some embodiments of this application, the solid electrolyte is in the form of clay.

[0056] It is understandable that the clay-like morphology of solid electrolytes provides excellent flexibility and plasticity, allowing them to better adapt to the surface morphology of electrode materials. This morphology facilitates the formation of a tight contact at the solid-solid interface, reducing interfacial impedance and improving interfacial stability. When in contact with electrode materials, the solid electrolyte can form a stable interfacial layer, reducing interfacial reactions and the formation of byproducts. This favorable interfacial contact contributes to the efficient transport of lithium ions, improving the battery's specific capacity and cycle performance.

[0057] In some embodiments of this application, the ionic conductivity of the solid electrolyte is greater than 1 mS / cm, for example, it can be a range of 1 mS / cm, 1.1 mS / cm, 1.2 mS / cm, 1.3 mS / cm, 1.5 mS / cm, 1.6 mS / cm, 1.7 mS / cm, 1.8 mS / cm, 2 mS / cm, 2.5 mS / cm, 3 mS / cm, 4 mS / cm, 5 mS / cm or any two of these.

[0058] The solid electrolyte in this application has an ionic conductivity greater than 1 mS / cm, which means that ions can migrate rapidly in the electrolyte, thereby improving the specific capacity and cycle performance of the battery.

[0059] In some embodiments of this application, in the X-ray diffraction pattern, the width of the full width at half maximum (FWHM) of the widest diffraction peak is greater than or equal to 1.35°, for example, it can be a range of 1.35°, 1.37°, 1.4°, 1.42°, 1.45°, 1.47°, 1.5°, 1.55°, 1.57°, 1.6°, 1.65° or any combination thereof.

[0060] It is understood that the widest diffraction peak in this application refers to the diffraction peak with the largest half-width among all the individual diffraction peaks with sharp shapes.

[0061] In this application, the width of the full width at half maximum (FWHM) of the widest diffraction peak in the X-ray diffraction pattern is within the above range, indicating that the solid electrolyte has an imperfect crystal structure, with a large proportion of amorphous state and disordered atomic arrangement. This disorder makes the solid electrolyte more prone to local deformation under external force, thereby improving the flexibility of the material, which is conducive to forming a tight contact at the solid-solid interface, reducing interface impedance, improving interface stability, facilitating the effective transport of lithium ions, and improving the specific capacity and cycle performance of the battery.

[0062] In some embodiments of this application, the Young's modulus of the solid electrolyte is less than or equal to 3 GPa, for example, it can be a range of 2 GPa, 2.1 GPa, 2.2 GPa, 2.3 GPa, 2.4 GPa, 2.5 GPa, 2.6 GPa, 2.7 GPa, 2.8 GPa, 2.9 GPa, 3 GPa or any two of these.

[0063] The Young's modulus of the solid electrolyte in this application falls within the aforementioned range, indicating that it possesses a certain degree of flexibility and elasticity. This allows the solid electrolyte to further form a stable interface layer when in contact with the electrode material, reducing interfacial reactions and the formation of byproducts. This favorable interfacial contact facilitates efficient ion transport, thereby improving the battery's specific capacity and cycle performance.

[0064] Secondly, this application provides a method for preparing the solid electrolyte as described above, comprising the following steps:

[0065] 1) A mixture is obtained by grinding a raw material system including lithium halide, lithium oxide, gallium halide, and halides containing element A;

[0066] 2) Under an inert atmosphere, the mixture was subjected to ball milling and heat treatment in sequence to obtain a solid electrolyte.

[0067] In step 1) of this application, the raw materials for forming solid electrolytes are placed in a mortar and manually ground to complete the initial mixing. The raw materials are uniformly mixed and the particle size is refined to obtain a mixture.

[0068] In step 2), the mixture (i.e., the mixed raw materials) is placed in a ball mill jar under an inert atmosphere, such as argon, for ball milling to obtain a solid electrolyte. Ball milling under an inert atmosphere avoids oxidation or other adverse chemical reactions, maintaining the purity and stability of the material. Ball milling further refines the particles and promotes the solid-state reaction, forming a uniform solid electrolyte. Ball milling can introduce lattice defects and increase disorder, which is beneficial for improving lithium-ion mobility. The refined particles and uniform material composition help form good interfacial contact between the electrolyte and electrode materials, reducing interfacial impedance. Furthermore, due to the synergistic effect of Ga and monovalent halide anions, halides can quickly agglomerate from powder, accelerating the reaction process. Heat treatment can promote the crystallization process of the material, which is beneficial for forming the desired crystal phase structure. It can also eliminate defects introduced during grinding or ball milling, relieve internal stress, and facilitate a uniform component distribution within the material, allowing the components to mix thoroughly and form a uniform solid solution.

[0069] The solid electrolyte preparation method of this application produces a halide solid electrolyte that does not contain precious metals or has a low content of precious metals, which has a cost advantage. Furthermore, the solid electrolyte has high ionic conductivity and good solid-solid interface contact with the electrode material. When applied to batteries, it can improve the specific capacity and cycle performance of the batteries.

[0070] In some embodiments of this application, the grinding time is 5 min to 30 min, for example, it can be a range of 5 min, 10 min, 15 min, 20 min, 25 min, 30 min or any two of these.

[0071] In some embodiments, the ball milling speed is 400 rpm to 600 rpm, for example, it can be a range of 400 rpm, 420 rpm, 450 rpm, 470 rpm, 500 rpm, 520 rpm, 550 rpm, 570 rpm, 600 rpm, or any two of these. The ball milling time is 0.5 h to 4 h, for example, it can be a range of 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, or any two of these. The ball-to-material ratio in the ball milling process is (10-40):1, for example, it can be a range of 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, or any two of these.

[0072] In some embodiments, the heat treatment temperature is 150°C-250°C, for example, it can be a range of 150°C, 170°C, 190°C, 200°C, 220°C, 240°C, 250°C, or any two of these. The time is 1h-4h, for example, it can be a range of 1h, 2h, 2.5h, 3h, 4h, or any two of these.

[0073] In some embodiments, the halide containing element A includes yttrium halide, and the molar ratio of yttrium halide to gallium halide is 1:(0.45-1.5), for example, it can be a range of 1:0.45, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5 or any two of these.

[0074] The grinding time in this application ensures thorough mixing of raw materials and initial particle refinement, avoiding particle agglomeration caused by over-grinding.

[0075] The rotational speed of ball milling provides sufficient energy to promote effective collisions and mixing between particles, which is beneficial for reducing lattice defects and disorder, thereby improving ionic conductivity. The milling time prevents over-refinement of particles. The ball-to-particle ratio optimizes energy transfer efficiency, providing greater grinding energy that promotes particle refinement and uniform mixing.

[0076] The temperature and time of heat treatment can effectively eliminate defects and internal stress in materials, enabling the components to be evenly distributed in the material. Moreover, the heat treatment process has low energy consumption, saving energy costs, reducing the risk of thermal degradation of materials, and effectively controlling grain growth.

[0077] When the molar ratio of yttrium halide to gallium halide is within the above range, a stable crystal structure can be formed, lattice parameters can be optimized, and the chemical stability and ionic conductivity of the solid electrolyte can be enhanced.

[0078] The preparation method of the solid electrolyte of the present application optimizes the material aspect, only requires ball milling synthesis in a very short time, avoids the problems of energy consumption and time cost caused by long-time ball milling, reduces the synthesis time by more than 90% compared with traditional ball milling, and can realize continuous synthesis in terms of process.

[0079] In a third aspect, the present application provides a positive electrode sheet, comprising the solid electrolyte as described above or the solid electrolyte prepared by the preparation method of the solid electrolyte as described above.

[0080] The positive electrode sheet provided by the present application comprises the above solid electrolyte, therefore, when the positive electrode sheet is applied to a battery, the specific capacity and cycling performance of the battery can be improved.

[0081] The present application does not limit the preparation method of the positive electrode sheet. In a specific embodiment, a positive electrode active material, a solid electrolyte, a conductive agent, a binder and the like can be mixed and dispersed in a solvent to prepare a positive electrode slurry, then the positive electrode slurry is coated on at least one functional surface of a positive electrode current collector, and after drying and rolling, the positive electrode sheet comprising the solid electrolyte therein of the present application is obtained; further, a dispersion liquid comprising the solid electrolyte can also be prepared, and the dispersion liquid is coated on the surface of the above positive electrode sheet to obtain a positive electrode sheet comprising the solid electrolyte both inside and on the surface.

[0082] Alternatively, a positive electrode active material, a conductive agent, a binder and the like are mixed and dispersed in a solvent to prepare a positive electrode slurry, and a dispersion liquid comprising a solid electrolyte can also be prepared at the same time. Then the positive electrode slurry is coated on at least one functional surface of a positive electrode current collector, after drying, the dispersion liquid is coated on the dried surface, and after drying again, rolling is performed to obtain the positive electrode sheet comprising the solid electrolyte on the surface of the present application.

[0083] The present application does not specifically limit the positive electrode active material, the conductive agent and the binder. For example, the positive electrode active material is selected from lithium iron phosphate (LiFePO4), lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide (Li z Ni x Co y Mn 1-x-y O2, wherein 0.95≤z≤1.05, x>0, y>0, 0<x+y<1), lithium manganate (LiMnO2), lithium nickel cobalt aluminum oxide (Li z Ni x Co y Al 1-x-y O2, wherein 0.95≤z≤1.05, x>0, y>0, 0.8≤x+y<1), lithium nickel cobalt manganese aluminum oxide (Li z Ni x Co y Mn w Al 1-x-y-wO2, where 0.95≤z≤1.05, x>0, y>0, w>0, 0.8≤x+y+w<1, nickel-cobalt-aluminum-tungsten materials, lithium-rich manganese-based solid solution cathode materials (xLi2MnO3·(1-x)LiMO2, where M=Ni / Co / Mn, 0<x<1), lithium nickel cobalt oxide (LiNi x CoyO2, where x>0, y>0, x+y=1), lithium nickel titanium magnesium oxide (LiNi x Ti y Mg z O2, where x>0, y>0, z>0, x+y+z=1), lithium nickel oxide (Li2NiO2), lithium spinel manganese oxide (LiMn2O4), nickel-cobalt-tungsten materials or combinations thereof; the conductive agent is selected from at least one of conductive carbon black, Ketjen black, conductive fiber, conductive polymer, acetylene black, carbon nanotubes, graphene, flake graphite, conductive oxide, metal particles; the binder is selected from at least one of polyvinylidene fluoride and its copolymer derivatives, polytetrafluoroethylene and its copolymer derivatives, polyacrylic acid and its copolymer derivatives, polyhexafluoropropylene and its copolymer derivatives.

[0084] Fourthly, this application provides a battery comprising a solid electrolyte as described above, a solid electrolyte prepared by the method described above, or a positive electrode as described above.

[0085] The battery described in this application exhibits outstanding performance in terms of specific capacity and cycle performance.

[0086] This application does not limit the method of battery preparation. For example, it can be prepared by sequentially stacking a positive electrode, a solid electrolyte, and a negative electrode and then encapsulating them. Alternatively, a basic cell can be formed by sequentially stacking a positive electrode, a separator, and a negative electrode, then injecting a precursor solution into it, fully impregnating it, and then baking it to obtain the lithium-ion battery of this application.

[0087] The positive and negative electrodes in the battery of this application have no special requirements compared to existing positive and negative electrodes in the art.

[0088] The technical solution of this application will be further described below with reference to specific embodiments.

[0089] Example 1

[0090] The preparation method of the solid electrolyte in this embodiment includes the following steps:

[0091] LiCl, YCl3, GaCl3, ZrCl4, CeCl3, AlCl3, and Li2O were weighed in a molar ratio of 0.8:0.2:0.2:0.2:0.2:0.2:0.5. The weighed raw materials were placed in a mortar and manually ground for 10 minutes for preliminary mixing to obtain a mixture. Under argon protection, the mixture was ball-milled for 2 hours at a speed of 500 rpm and a ball-to-material ratio of 25:1 to obtain a solid electrolyte precursor. The solid electrolyte precursor was then heat-treated at 200℃ for 2 hours to obtain a solid electrolyte. The solid electrolyte had a clay-like morphology. As shown in Figure 1, the X-ray diffraction pattern included 2θ diffraction peaks located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

[0092] Example 2

[0093] The preparation method of the solid electrolyte in Example 2 is basically the same as that in Example 1, except that LiF, YF3, GaF3, ZrF4, CeF3, AlF3, and Li2O are weighed in a molar ratio of 0.8:0.2:0.2:0.2:0.2:0.2:0.5. The resulting solid electrolyte has a clay-like morphology. As shown in Figure 2, the X-ray diffraction pattern includes diffraction peaks with 2θ located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

[0094] Example 3

[0095] The preparation method of the solid electrolyte in Example 3 is basically the same as that in Example 1, except that LiF, YF3, GaF3, ZrF4, CeF3, AlF3, LiCl, and Li2O are weighed in a molar ratio of 0.4:0.2:0.2:0.2:0.2:0.5:0.25. The resulting solid electrolyte has a clay-like morphology. As shown in Figure 3, the X-ray diffraction pattern includes 2θ diffraction peaks located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

[0096] Example 4

[0097] The preparation method of the solid electrolyte in Example 4 is basically the same as that in Example 1, except that LiF, YF3, GaF3, ZrF4, CeF3, AlF3, LiCl, and Li2O are weighed in a molar ratio of 0.4:0.35:0.35:0.1:0.1:0.1:0.5:0.25. The resulting solid electrolyte has a clay-like morphology. In the X-ray diffraction pattern, it includes 2θ diffraction peaks located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

[0098] Example 5

[0099] The preparation method of the solid electrolyte in Example 5 is basically the same as that in Example 1, except that LiF, YF3, GaF3, ZrF4, CeF3, AlF3, LiCl, and Li2O are weighed in a molar ratio of 0.4:0.1:0.3:0.2:0.2:0.2:0.5:0.25. The resulting solid electrolyte has a clay-like morphology. In the X-ray diffraction pattern, it includes 2θ diffraction peaks located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

[0100] Example 6

[0101] The preparation method of the solid electrolyte in Example 6 is basically the same as that in Example 1, except that LiF, YF3, GaF3, ZrF4, CeF3, AlF3, LiCl, and Li2O are weighed in a molar ratio of 0.4:0.3:0.1:0.2:0.2:0.2:0.5:0.25. The resulting solid electrolyte has a clay-like morphology. In the X-ray diffraction pattern, it includes 2θ diffraction peaks located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

[0102] Example 7

[0103] The preparation method of the solid electrolyte in Example 7 is basically the same as that in Example 1, except that LiF, YF3, GaF3, ZrF4, CeF3, AlF3, LiCl, and Li2O are weighed in a molar ratio of 0.4:0.27:0.13:0.2:0.2:0.2:0.5:0.25. The resulting solid electrolyte has a clay-like morphology. In the X-ray diffraction pattern, it includes 2θ diffraction peaks located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

[0104] Example 8

[0105] The preparation method of the solid electrolyte in Example 8 is basically the same as that in Example 1, except that LiF, YF3, GaF3, ZrF4, CeF3, AlF3, LiCl, and Li2O are weighed in a molar ratio of 0.4:0.17:0.23:0.2:0.2:0.2:0.5:0.25. The resulting solid electrolyte has a clay-like morphology. In the X-ray diffraction pattern, it includes 2θ diffraction peaks located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

[0106] Example 9

[0107] The preparation method of the solid electrolyte in Example 9 is basically the same as that in Example 3, except that the grinding time is changed to 5 min, the ball milling speed is changed to 400 rpm, the time is changed to 0.5 h, the ball-to-material ratio is changed to 40:1, and the solid electrolyte precursor is heat-treated at 250 °C for 1 h. The resulting solid electrolyte has a clay-like morphology. In the X-ray diffraction pattern, it includes 2θ diffraction peaks located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

[0108] Example 10

[0109] The preparation method of the solid electrolyte in Example 10 is basically the same as that in Example 3, except that the grinding time is changed to 30 min, the ball milling speed is changed to 600 rpm, the time is changed to 4 h, the ball-to-material ratio is changed to 10:1, and the solid electrolyte precursor is heat-treated at 150 °C for 4 h. The resulting solid electrolyte has a clay-like morphology. In the X-ray diffraction pattern, it includes 2θ diffraction peaks located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

[0110] Example 11

[0111] The preparation method of the solid electrolyte in Example 11 is basically the same as that in Example 1, except that LiF, YF3, GaF3, ZrF4, InF3, HoF3, LiCl, and Li2O are weighed in a molar ratio of 0.4:0.2:0.2:0.2:0.2:0.5:0.25. The resulting solid electrolyte has a clay-like morphology. In the X-ray diffraction pattern, it includes 2θ diffraction peaks located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

[0112] Example 12

[0113] The preparation method of the solid electrolyte in Example 12 is basically the same as that in Example 1, except that LiF, YF3, GaF3, ZrF4, TaF5, NbF5, LiBr, and Li2O are weighed in a molar ratio of 0.4:0.2:0.2:0.2:0.2:0.5:0.25. The resulting solid electrolyte has a clay-like morphology. In the X-ray diffraction pattern, it includes 2θ diffraction peaks located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

[0114] Example 13

[0115] The preparation method of the solid electrolyte in Example 13 is basically the same as that in Example 1, except that LiCl, YCl3, GaCl3, ZrCl4, CeCl3, AlCl3, and Li2O are weighed in a molar ratio of 0.8:0.2:0.2:0.2:0.2:0.2:0.4. The resulting solid electrolyte has a clay-like morphology. In the X-ray diffraction pattern, it includes 2θ diffraction peaks located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

[0116] Comparative Example 1

[0117] The preparation method of the solid electrolyte in Comparative Example 1 includes the following steps:

[0118] LiCl and YCl3 were weighed in a molar ratio of 3:1. The weighed raw materials were mixed and then ball-milled for 40 hours at a speed of 500 rpm with a ball-to-material ratio of 30:1 to obtain a solid electrolyte. The solid electrolyte was in powder form. As shown in Figure 1, the X-ray diffraction pattern included 2θ diffraction peaks at 31°-31.6°, 40.6°-41.2°, and 48.4°-49.0°.

[0119] Comparative Example 2

[0120] The preparation method of the solid electrolyte in Comparative Example 2 includes the following steps:

[0121] LiCl and InCl3 were weighed in a molar ratio of 3:1. The weighed raw materials were mixed and ball-milled for 40 hours at a speed of 500 rpm with a ball-to-material ratio of 30:1. The ball-milled sample was then heat-treated at 260℃ for 5 hours to obtain a solid electrolyte. The solid electrolyte was in powder form. As shown in Figure 4, the X-ray diffraction pattern included 2θ diffraction peaks at 14.5°–15.1°, 34.0°–34.7°, and 49.1°–50.0°.

[0122] Comparative Example 3

[0123] The preparation method of the solid electrolyte in Comparative Example 3 is basically the same as that in Example 1, except that LiF, YF3, GaF3, ZrF4, CeF3, AlF3, and LiCl are weighed in a molar ratio of 0.4:0.2:0.2:0.2:0.2:0.2:0.5. The solid electrolyte is in powder form. As shown in Figure 5, the X-ray diffraction pattern includes diffraction peaks with 2θ at 25.8°-26.1°, 27.2°-28.1°, and 46.8°-48.1°.

[0124] Comparative Example 4

[0125] The preparation method of the solid electrolyte in Comparative Example 4 is basically the same as that in Example 1, except that LiF, YF3, ZrF4, CeF3, AlF3, LiCl, and Li2O are weighed in a molar ratio of 0.4:0.25:0.25:0.25:0.25:0.5:0.25. The solid electrolyte is in powder form. As shown in Figure 6, the X-ray diffraction pattern includes diffraction peaks with 2θ at 25.6°-26.3°, 27.3°-28.3°, and 34.6°-35.4°.

[0126] Comparative Example 5

[0127] The preparation method of the solid electrolyte in Comparative Example 5 is basically the same as that in Example 1, except that Li2O and Ga2O3 are weighed in a molar ratio of 1:1. The solid electrolyte is in powder form. As shown in Figure 7, the X-ray diffraction pattern includes diffraction peaks with 2θ located at 30.5°-30.8°, 35.4°-35.7°, and 50.9°-51.3°.

[0128] Experimental example:

[0129] 1. Determination of the types and contents of elements in solid electrolytes: Take 200 mg of solid electrolyte sample in a sealed instrument, and further seal it with sealing tape to avoid exposure to air. Then transfer it to an ICP elemental analyzer for ICP characterization to analyze the elemental composition and corresponding contents.

[0130] 2. XRD Testing: A certain amount of solid electrolyte sample was placed on the XRD sample stage and sealed with KAPTON tape to prevent moisture from interfering with the sample's characteristic peaks. Cu-Kα radiation was used for the XRD test, and the X-ray diffraction analysis was performed using Bruker's D Advance. The position of the widest diffraction peak in the XRD pattern was determined, and its full width at half maximum (FWHM) was measured.

[0131] 3. Ionic conductivity: 200 mg of solid electrolyte was placed in a solid mold and pressed into a tablet using a pressure of 3 tons, maintaining the pressure for 3 minutes. Then, a carbon-coated aluminum foil was attached to each side of the pressed solid electrolyte tablet as a current collector, assembling the battery and applying external pressure. The test method was AC impedance method, with a test frequency of 10 MHz-1 Hz.

[0132] 4. Specific capacity: Batteries were prepared using the solid electrolytes obtained in the examples and comparative examples. Specifically, the solid electrolyte, ternary cathode material Ni83, and conductive carbon were mixed in a mass ratio of 30:70:3 to obtain a cathode composite material; Li-In alloy was used as the anode material; a certain amount of solid electrolyte was weighed, poured into a battery mold, and pressed into a sheet under a certain pressure to obtain a solid electrolyte layer; the solid electrolyte layer was placed between the cathode sheet formed by the cathode composite material and the anode sheet formed by the anode material to obtain the battery.

[0133] At 25℃, the battery was charged at a constant current rate of 0.1C / 1C to 4.3V, and then charged at a constant voltage rate of 4.3V until the current was equal to 0.05C. The charging capacity at this time was recorded as the first charge specific capacity. After that, the battery was left to stand for 5 minutes, and then discharged at a constant current rate of 0.1C / 1C to a voltage of 2.5V. The discharge capacity at this time was recorded as the battery's first discharge specific capacity.

[0134] 5. Cycle performance: Under 25℃ conditions, the battery is charged at a constant current rate of 1C to the upper limit voltage, then charged at a constant voltage rate of 0.5C to the lower limit voltage, and then discharged at a discharge rate of 1C to the lower limit voltage. This charge-discharge cycle is repeated 100 times. The discharge capacity Q1 at the first cycle and the discharge capacity Q at the 100th cycle are measured. 100 The capacity retention rate after 100 cycles is Q = Q 100 / Q1*100%.

[0135] 6. Young's Modulus Test: Using an atomic force microscope and quantitative nanotechnology imaging mode, the corresponding solid electrolyte sample was examined. The interaction between the probe and the sample was used to obtain Young's modulus data, with a constant loading rate of 400 nm·s. -1 .

[0136] Figure 1 is an XRD pattern of the solid electrolyte of Example 1 and Comparative Example 1 of this application.

[0137] As shown in Figure 1, the solid electrolyte of Comparative Example 1 has a higher crystalline content, resulting in sharper characteristic peaks; the solid electrolyte of Example 1 has an increased amorphous content, resulting in broader characteristic peaks. Furthermore, the ratio of the peak intensity of the diffraction peak at 27°-29° for the solid electrolyte of Example 1 to the peak intensity of the diffraction peak at 31°-31.6° for the solid electrolyte of Comparative Example 1 is 1:7.86, indicating that the diffraction peak intensity of the solid electrolyte of Example 1 is weaker, the amorphous content is higher, and the solid electrolyte exhibits a clay-like structure.

[0138] Figure 8a shows the morphology of the solid electrolyte of Example 1 of this application, and b shows the morphology of the solid electrolyte of Comparative Example 1 of this application.

[0139] As can be seen from Figure 8, the solid electrolyte of Example 1 exhibits a distinct clay-like appearance and has a certain degree of flexibility; the solid electrolyte of Comparative Example 1 exhibits a powder-like appearance.

[0140] Table 1

[0141] As shown in Table 1, the solid electrolyte provided in this application, by limiting its chemical composition and the 2θ diffraction peak in XRD, can improve the disorder of the solid electrolyte, increase its ionic conductivity, and enhance its flexibility. This allows the solid electrolyte to form a stable interface layer when in contact with electrode materials, reducing interfacial reactions and the formation of byproducts. This good interfacial contact facilitates efficient ion transport, thereby improving the battery's specific capacity and cycle performance.

[0142] A comparison of Examples 1-13 with Comparative Examples 1-5 shows that the solid electrolyte provided in this application has a wider half-peak width and a lower Young's modulus, indicating that the amorphous state accounts for a larger proportion and the electrolyte has stronger flexibility.

[0143] The high-entropy halide solid electrolytes synthesized in Examples 1-13 showed a significant improvement in ionic conductivity compared to the two most typical halide solid electrolytes in Comparative Examples 1-2, with a substantial reduction in synthesis time and cost.

[0144] Compared to Examples 1-2, Example 3 further introduces different types of anions to enhance the disorder in the crystal structure, thereby inducing more charge carriers and crystal defect sites, significantly enhancing the lithium-ion conductivity, and fully demonstrating the advantages of high-entropy materials.

[0145] Compared to Example 3, Examples 4, 7, and 8 changed the proportion of metal elements, and the ionic conductivity decreased to varying degrees, indicating that the molar ratio of any metal element in A to Ga is (0.8-1.2):1, which is more conducive to the transport of lithium ions.

[0146] Compared to Example 3, Examples 5-6 changed the proportions of Y and Ga elements in the metal elements, resulting in a significant decrease in ionic conductivity. This indicates that a molar ratio of Y to Ga of 1:(0.45-1.5) is more conducive to lithium ion transport.

[0147] After removing O and Ga elements from Comparative Examples 3 and 4, respectively, the ionic conductivity decreased significantly, demonstrating the importance of O and Ga elements in the high-entropy halide solid electrolyte of this application.

[0148] Compared to Examples 3-12, Example 1 has a higher content of O element, and its widest diffraction peak has a half-width of less than 1.35° and a Young's modulus greater than 3 GPa, indicating that its amorphous state ratio is lower than that of Examples 3-12, and its flexibility is worse than that of Examples 3-12, resulting in poorer specific capacity and cycle performance of the battery.

[0149] Compared to Example 1, Example 13 has a slightly lower O content, and its widest diffraction peak has a half-width of less than 1.35°, but its Young's modulus is less than 3 GPa, which makes the battery's specific capacity and cycle performance better than Example 1.

[0150] Finally, it should be noted that other embodiments of this application will readily conceive of by those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and alterations may be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A solid electrolyte, characterized in that, The chemical composition of the solid electrolyte is Li x Ga y A a D b O c Wherein, 0.5≤x≤2.0, 0.1≤y≤0.5, 0.1≤a≤1, 3.5≤b≤5, 0.25≤c≤1.5; A includes four or more of Y, In, Al, La, Ce, Ho, Zr, Ta, and Nb, and D includes one or more of F, Cl, and Br; In the X-ray diffraction pattern, there are diffraction peaks of 2θ located at 24°-26°, 27°-29°, 42°-46°, and 49°-54°.

2. The solid electrolyte according to claim 1, characterized in that, The A element includes Y, and the molar ratio of Y to Ga is 1:(0.45-1.5).

3. The solid electrolyte according to claim 1 or 2, characterized in that, The D includes two or more of F, Cl and Br.

4. The solid electrolyte according to any one of claims 1-3, characterized in that, The D includes at least F.

5. The solid electrolyte according to any one of claims 1-4, characterized in that, The molar ratio of any metal element in A to Ga is (0.8-1.2):

1.

6. The solid electrolyte according to any one of claims 1-5, characterized in that, The solid electrolyte is in the form of clay.

7. The solid electrolyte according to any one of claims 1-6, characterized in that, The ionic conductivity of the solid electrolyte is greater than 1 mS / cm.

8. The solid electrolyte according to any one of claims 1-7, characterized in that, In X-ray diffraction patterns, the full width at half maximum (FWHM) of the widest diffraction peak is greater than or equal to 1.35°.

9. The solid electrolyte according to any one of claims 1-8, characterized in that, The Young's modulus of the solid electrolyte is less than or equal to 3 GPa.

10. A method for preparing a solid electrolyte according to any one of claims 1-9, characterized in that, Includes the following steps: 1) A mixture is obtained by grinding a raw material system including lithium halide, lithium oxide, gallium halide, and halides containing element A; 2) Under an inert atmosphere, the mixture is subjected to ball milling and heat treatment in sequence to obtain the solid electrolyte.

11. The method for preparing a solid electrolyte according to claim 10, characterized in that, The grinding process takes 5-30 minutes. And / or, the ball milling process is performed at a speed of 400 rpm to 600 rpm for 0.5 h to 4 h, with a ball-to-material ratio of (10-40):1; And / or, the heat treatment temperature is 150℃-250℃, and the time is 1h-4h; And / or, the halide containing element A includes yttrium halide, and the molar ratio of yttrium halide to gallium halide is 1:(0.45-1.5).

12. A positive electrode plate, characterized in that, Solid electrolytes include those prepared by the method of any one of claims 1-9 or the method of preparing solid electrolytes according to claim 10 or 11.

13. A battery, characterized in that, This includes the solid electrolyte as described in any one of claims 1-9, the solid electrolyte prepared by the method described in claim 10 or 11, or the positive electrode as described in claim 12.

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