Halide solid state electrolyte, method of making and new energy vehicle solid state battery

Abstract

The application provides a halide solid electrolyte, a preparation method thereof and a new energy automobile solid battery. Specifically, the preparation method comprises the following steps: under the protection of an inert atmosphere, mixing a host component, a rare earth element type dopant, a transition metal element type dopant, a main group metal element type dopant, an inorganic modifier and an organic modifier to obtain a mixed powder; under the protection of an inert atmosphere, heating the mixed powder to 450-600 DEG C for a melting reaction, the reaction time is 4-8 hours, and then cooling to room temperature to obtain a halide solid electrolyte crude product; and crushing and drying the halide solid electrolyte crude product to obtain a halide solid electrolyte. The halide solid electrolyte of the application realizes the synergistic improvement of ion conductivity, an electrochemical window and humidity stability, and improves the mechanical performance. The preparation process is simple, the energy consumption is low, the production can be scaled up, and the material and manufacturing costs are greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of solid-state battery materials technology for new energy vehicles, specifically relating to a halide solid electrolyte, its preparation method, and a solid-state battery for new energy vehicles. Background Technology

[0002] Lithium-ion batteries, as core energy storage devices in the new energy field, have been widely used in new energy vehicles, portable electronic devices, and large-scale energy storage power stations. Traditional liquid lithium-ion batteries rely on organic electrolytes, which, while possessing high ionic conductivity, pose safety hazards such as flammability, explosiveness, and leakage. They are also prone to thermal runaway under extreme conditions such as high temperature, overcharging, and short circuits, making it difficult to meet the application requirements of high safety and high energy density. Solid-state electrolytes have therefore become the core research and development direction for next-generation lithium-ion batteries, with halide solid-state electrolytes becoming a research hotspot due to their comprehensive performance advantages.

[0003] Currently, solid electrolytes are mainly classified into three categories: oxides, sulfides, and halides. However, each system has significant technical shortcomings. Oxide solid electrolytes have a wide electrochemical stability window and good air stability, but their room temperature ionic conductivity is low, and they are mechanically brittle and have poor contact with the electrode interface, requiring high-temperature sintering for densification, which increases the preparation cost and process complexity. Sulfide solid electrolytes have high room temperature ionic conductivity and good mechanical ductility, but they are highly sensitive to air, easily reacting with water and oxygen to release toxic hydrogen sulfide gas. They also have a narrow electrochemical window and poor compatibility with high-voltage cathode materials, requiring additional protective coatings.

[0004] Halogen solid electrolytes have become an important development direction in the field of solid electrolytes due to their combination of high room temperature ionic conductivity, wide electrochemical window, good mechanical plasticity and compatibility with high voltage cathode materials. Existing halide solid electrolytes are mainly single metal halide and partially doped modified systems, but their industrial application is still constrained by multiple technical bottlenecks: First, there is still room for improvement in ionic conductivity. The conductivity of single systems differs significantly from that of liquid electrolytes, and doped modified systems are prone to problems such as difficulty in controlling doping amount, impurity phase generation, and decreased stability. Second, humidity stability is poor. Most halides are prone to hydrolysis to generate impurities, leading to a sharp decline in ionic conductivity. Surface modification schemes are also difficult to fundamentally solve this problem and may even increase interfacial resistance. Third, the electrochemical window is difficult to match with new-generation high-voltage cathode materials. Under high voltage, they are prone to oxidation and decomposition, affecting battery cycle life. Fourth, the preparation process has defects. Solid-phase methods have long cycles, high energy consumption, and poor product uniformity. Liquid-phase methods have cumbersome drying steps and low universality. Gas-phase methods are only suitable for thin film preparation and are difficult to scale up. Fifth, material and production costs remain high. The demand for high lithium content in traditional systems increases the dependence on lithium resources, and some systems use precious metal elements. Coupled with stringent production and storage environment requirements, this further increases industrialization costs.

[0005] Existing modification methods for halide solid electrolytes mostly focus on single-element doping or surface coating, failing to address the aforementioned issues synergistically at the composition design level. Furthermore, some doped systems suffer from poor universality and high preparation difficulty. Therefore, developing a halide solid electrolyte with a rationally designed composition, high ionic conductivity, wide electrochemical window, good humidity stability, and simple and cost-effective preparation process is of great significance for promoting the industrial application of all-solid-state lithium-ion batteries in new energy vehicles. Summary of the Invention

[0006] Based on the technical problems described above, this invention aims to overcome the performance shortcomings of existing halide solid electrolytes, such as low ionic conductivity, poor humidity stability, and narrow electrochemical window. It also addresses the technical problems of complex preparation processes, high material and production costs, and the difficulty in synergistically optimizing multiple performance aspects through modification methods. The invention provides a novel halide solid electrolyte, its preparation method, and a solid-state battery for new energy vehicles, achieving synergistic improvement in multiple electrolyte performance aspects, simplifying the preparation process, reducing costs, and ultimately improving the cycle life and safety of all-solid-state batteries to meet the application requirements of high energy density and high safety.

[0007] Specifically, according to one aspect of the present invention, a method for preparing a halide solid electrolyte is provided, the method comprising the following steps: (1) Under an inert atmosphere, the main component, rare earth element dopants, transition metal element dopants, main group metal element dopants, inorganic modifiers and organic modifiers are mixed to obtain a mixed powder; (2) The mixed powder is heated to 450-600°C, preferably 450-500°C, under an inert atmosphere for a melting reaction for 4-8 hours, and then cooled to room temperature to obtain crude halide solid electrolyte; (3) Under an inert atmosphere, the crude halide solid electrolyte is pulverized and dried to obtain the halide solid electrolyte, wherein: The main component is a mixture of LiCl, LiBr and LiI, wherein, based on the total weight of LiCl, LiBr and LiI as 100%, LiCl accounts for 40-60%, LiBr accounts for 20-35%, and LiI accounts for 15-30%. The rare earth element dopant is a mixture of Y₂O₃ and La₂O₃; The transition metal dopant is a mixture of ZrCl4 and HfCl4; The main group metal element dopant is a mixture of Al2O3 and Ga2O3; The inorganic modifier is selected from one or more of Li2SO4, Li3PO4, and Li2CO3; The organic modifier is selected from one or more of polymethyl methacrylate, polyethylene glycol, and polyvinylidene fluoride; and Based on the total weight of the main component, rare earth element dopants, transition metal element dopants, main group metal element dopants, inorganic modifiers, and organic modifiers as 100%, the main component accounts for 70-85%, rare earth element dopants account for 2-10%, transition metal element dopants account for 2-10%, main group metal element dopants account for 1-5%, inorganic modifiers account for 0.5-6%, and organic modifiers account for 0.5-4%.

[0008] According to certain preferred embodiments of the present invention, the rare earth element dopant is a mixture of Y2O3 and La2O3 in a weight ratio of 3:1 to 5:1.

[0009] According to certain preferred embodiments of the present invention, the transition metal element dopant is a mixture of ZrCl4 and HfCl4 in a weight ratio of 2:1 to 4:1.

[0010] According to certain preferred embodiments of the present invention, the main group metal element dopant is a mixture of Al2O3 and Ga2O3 in a weight ratio of 1:1 to 2:1.

[0011] According to certain preferred embodiments of the present invention, the inorganic modifier is a mixture of Li2SO4 and Li3PO4 in a weight ratio of 1:1 to 3:1.

[0012] According to certain preferred embodiments of the present invention, the organic modifier is a mixture of polymethyl methacrylate and polyethylene glycol in a weight ratio of 2:1 to 5:1.

[0013] According to certain preferred embodiments of the present invention, the polymethyl methacrylate has a weight-average molecular weight in the range of 10,000-100,000 Da and an average particle size in the range of 50-80 μm.

[0014] According to certain preferred embodiments of the present invention, the polyethylene glycol has a weight-average molecular weight in the range of 2000-8000 Da and an average particle size in the range of 1-10 μm.

[0015] According to certain preferred embodiments of the present invention, the polyvinylidene fluoride has a weight-average molecular weight in the range of 100,000-300,000 Da and an average particle size in the range of 1-50 μm.

[0016] According to certain preferred embodiments of the present invention, the preparation method further includes, before step (1): drying and pulverizing the main component, rare earth element dopant, transition metal element dopant, main group metal element dopant and inorganic modifier respectively under an inert atmosphere.

[0017] According to certain preferred embodiments of the present invention, the drying is carried out for 8-12 hours under conditions of vacuum degree ≤10Pa and temperature 80-120°C; the pulverization is carried out by a planetary ball mill with a ball milling speed of 200-300r / min, a ball milling time of 2-4 hours, and a ball-to-material ratio of 10:1-15:1.

[0018] According to certain preferred embodiments of the present invention, in step (1), the mixing includes: first premixing the main components, then adding rare earth element dopants, transition metal element dopants and main group metal element dopants for mixing, and finally adding inorganic modifiers and organic modifiers for mixing.

[0019] According to certain preferred embodiments of the present invention, in step (2), the heating rate is 5-10°C / min.

[0020] According to certain preferred embodiments of the present invention, in step (2), the cooling rate is 3-5°C / min.

[0021] According to certain preferred embodiments of the present invention, in step (3), the pulverization is carried out by a planetary ball mill with a ball milling speed of 250-300 r / min, a ball milling time of 2-3 hours, and a ball-to-material ratio of 12:1-15:1; the drying is carried out for 4-6 hours under conditions of vacuum degree ≤10Pa and temperature of 60-80°C.

[0022] According to another aspect of the present invention, a halide solid electrolyte is provided, which is prepared according to the method described above.

[0023] According to certain preferred embodiments of the present invention, the room temperature ionic conductivity of the halide solid electrolyte is 2.6-5.0 mS•cm. -1 .

[0024] According to certain preferred embodiments of the present invention, the electrochemical window of the halide solid electrolyte is 0-5.2V (vs. Li / Li). + ).

[0025] According to certain preferred embodiments of the present invention, after the halide solid electrolyte is exposed to an environment with a humidity of 5-10% for 72 hours, the ionic conductivity retention rate is greater than or equal to 87%.

[0026] According to certain preferred embodiments of the present invention, the Young's modulus of the halide solid electrolyte is 1.8-2.2 GPa.

[0027] According to another aspect of the present invention, a solid-state battery for new energy vehicles is provided, the solid-state battery for new energy vehicles comprising a positive electrode, a negative electrode, a solid electrolyte layer and a shell, wherein the solid electrolyte layer is prepared from the halide solid electrolyte described above.

[0028] According to certain preferred embodiments of the present invention, the thickness of the solid electrolyte layer is 10-50 μm.

[0029] According to certain preferred embodiments of the present invention, the positive electrode comprises a positive electrode active material, a conductive agent, and the halide solid electrolyte.

[0030] According to certain preferred embodiments of the present invention, the content of the positive electrode active material is 65-75% based on 100% by weight of the positive electrode, the content of the conductive agent is 8-10%, and the content of the halide solid electrolyte is 15-25%.

[0031] According to certain preferred embodiments of the present invention, the surface of the negative electrode is provided with an interface modification layer, the interface modification layer comprising the halide solid electrolyte and metal alloy powder.

[0032] According to certain preferred embodiments of the present invention, the metal alloy powder is selected from at least one of lithium-based alloys or sodium-based alloys.

[0033] According to certain preferred embodiments of the present invention, the lithium-based alloy is selected from at least one of Li-In alloy or Li-Sn alloy, and the sodium-based alloy is Na-Sn alloy.

[0034] According to certain preferred embodiments of the present invention, the content of the halide solid electrolyte is 75-80% and the content of the metal alloy powder is 20-25%, based on 100% of the weight of the interface modification layer.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Breaking through the limitations of a single main component, a lithium-based halide mixture is used as the main component, combined with a ternary doping system of rare earth, transition metals, and main group metals, as well as inorganic-organic composite modifiers, to achieve synergistic optimization of ionic conductivity, electrochemical window, and humidity stability, thus solving the bottleneck of existing systems that cannot take multiple properties into account.

[0036] 2. The room temperature ionic conductivity is significantly improved while the electronic conductivity is low, which meets the insulation requirements of solid electrolytes, avoids self-discharge and safety hazards, and is suitable for the needs of high power density all-solid-state batteries.

[0037] 3. It is highly compatible with high-voltage cathode materials such as lithium-rich manganese-based materials, avoiding oxidation and decomposition under high voltage, and effectively improving battery cycle life and energy density.

[0038] 4. By reducing the lithium content, the interaction between lithium ions and water molecules is reduced, significantly improving air stability and lowering environmental requirements for production, storage, and use.

[0039] 5. No high-temperature sintering is required; it can be prepared by melting and cooling crystallization. The process is simple, energy-efficient, and has a short cycle. It also reduces dependence on lithium resources, avoids the use of precious metals, significantly reduces material and industrial production costs, and is easy to scale up.

[0040] 6. It has excellent mechanical properties and belongs to the category of soft electrolytes. It can form a high-density structure by cold pressing, has good contact with the positive and negative electrode interfaces, effectively reduces the interface resistance, and improves the interface compatibility.

[0041] 7. Solid-state batteries equipped with this electrolyte have no safety hazards associated with liquid electrolytes, and their cycle performance and stability under extreme conditions such as high temperature and overcharge are significantly improved. Attached Figure Description

[0042] The accompanying drawings are provided in this specification to more clearly explain the technical solutions of the present invention; however, the art is not limited thereto.

[0043] Figure 1 A flowchart illustrating the preparation process of a halide solid electrolyte according to the present invention is shown. Figure 2 The image shown is a scanning electron microscope (SEM) image of the halide solid electrolyte prepared in Example 1; Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It will be understood that other embodiments may be implemented without departing from the scope or spirit of the invention. Therefore, the following detailed description is non-limiting.

[0045] Unless otherwise specified, all figures used in this specification to represent characteristic dimensions, quantities, and physical properties should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters listed in the foregoing specification are approximations, and those skilled in the art can appropriately modify these approximations to obtain the desired properties using the teachings disclosed herein.

[0046] As mentioned above, existing halide solid electrolytes have low ionic conductivity, and doping modification easily leads to impurities and decreased stability, making it difficult to meet the requirements of high-power-density batteries. They also exhibit poor humidity stability, are prone to hydrolysis causing a sharp drop in conductivity, and surface modification cannot fundamentally solve this problem and can easily increase interfacial resistance. Furthermore, their electrochemical window is narrow, making them difficult to match with high-voltage cathode materials such as lithium-rich manganese-based materials, and they are prone to oxidation and decomposition under high voltage. Their preparation processes also suffer from drawbacks such as long cycles in solid-phase methods, cumbersome steps in liquid-phase methods, and difficulty in scaling up gas-phase methods. The requirement for high lithium content drives up material costs, and the use of precious metals in some systems further exacerbates the cost problem. The stringent environmental requirements for production and storage also increase industrialization costs. In addition, existing modification methods are mostly single-element doping or surface coating, which cannot comprehensively address the aforementioned performance and process issues at the component design level. Some doped systems also suffer from poor universality and high preparation difficulty, hindering the industrialization of all-solid-state batteries. This invention aims to solve these problems.

[0047] Specifically, according to one aspect of the present invention, a method for preparing a halide solid electrolyte is provided, the method comprising the following steps: (1) Under an inert atmosphere, the main component, rare earth element dopants, transition metal element dopants, main group metal element dopants, inorganic modifiers and organic modifiers are mixed to obtain a mixed powder; (2) The mixed powder is heated to 450-600°C under an inert atmosphere for a melting reaction for 4-8 hours, and then cooled to room temperature to obtain crude halide solid electrolyte; (3) Under an inert atmosphere, the crude halide solid electrolyte is pulverized and dried to obtain the halide solid electrolyte, wherein: The main component is a mixture of LiCl, LiBr and LiI, wherein, based on the total weight of LiCl, LiBr and LiI as 100%, LiCl accounts for 40-60%, LiBr accounts for 20-35%, and LiI accounts for 15-30%. The rare earth element dopant is a mixture of Y₂O₃ and La₂O₃; The transition metal dopant is a mixture of ZrCl4 and HfCl4; The main group metal element dopant is a mixture of Al2O3 and Ga2O3; The inorganic modifier is selected from one or more of Li2SO4, Li3PO4, and Li2CO3; The organic modifier is selected from one or more of polymethyl methacrylate, polyethylene glycol, and polyvinylidene fluoride; and Based on the total weight of the main component, rare earth element dopants, transition metal element dopants, main group metal element dopants, inorganic modifiers, and organic modifiers as 100%, the main component accounts for 70-85%, rare earth element dopants account for 2-10%, transition metal element dopants account for 2-10%, main group metal element dopants account for 1-5%, inorganic modifiers account for 0.5-6%, and organic modifiers account for 0.5-4%.

[0048] Figure 1 The flowchart illustrating the preparation process of a halide solid electrolyte according to the present invention is shown, specifically including: (1) Under an inert atmosphere, the main component, rare earth element dopants, transition metal element dopants, main group metal element dopants, inorganic modifiers and organic modifiers are mixed to obtain a mixed powder; (2) The mixed powder is heated to 450-600°C under an inert atmosphere for a melting reaction for 4-8 hours, and then cooled to room temperature to obtain crude halide solid electrolyte; (3) Under an inert atmosphere, the crude halide solid electrolyte is crushed and dried to obtain the halide solid electrolyte.

[0049] Specifically, according to one aspect of the present invention, a method for preparing a halide solid electrolyte is provided. The method optimizes the electrolyte performance by combining multi-component synergistic design with a mild melting process, while taking into account the simplicity and scalability of the preparation process.

[0050] The preparation method specifically includes the following steps: (1) Under an inert atmosphere, the main component, rare earth element dopants, transition metal element dopants, main group metal element dopants, inorganic modifiers, and organic modifiers are mixed to obtain a mixed powder. This step is carried out entirely under an inert atmosphere (preferably an inert gas atmosphere such as argon or nitrogen, and more preferably an argon atmosphere with a water oxygen content ≤0.1ppm) to avoid side reactions such as hydrolysis and oxidation caused by contact between the raw materials and air, ensuring the purity and reactivity of the raw materials, and laying the foundation for the full progress of the subsequent melting reaction and the stability of the product performance. The raw materials are mixed in precise proportions to achieve uniform dispersion of the components at the microscopic level, avoiding problems such as impurity phase formation and performance fluctuations caused by uneven concentration of local components.

[0051] (2) The mixed powder is heated to 450-600°C, preferably 450-500°C, under an inert atmosphere for a melting reaction for 4-8 hours, and then cooled to room temperature to obtain a crude halide solid electrolyte. This invention abandons the high-temperature sintering process of traditional solid-state methods, and uses a medium-low temperature melting reaction at 450-600°C, preferably 450-500°C, which significantly reduces energy consumption and equipment requirements. Simultaneously, the diffusion rate of each component in the molten state is significantly improved, achieving atomic-level uniform fusion of the dopant and the main component, effectively solving the technical problems of poor product uniformity and low doping efficiency in solid-state methods. By precisely controlling the heating rate, melting temperature, and holding time, the reaction is ensured to proceed fully while avoiding problems such as lithium volatilization and product crystal distortion caused by excessively high temperatures and long reaction times. The rate regulation of the cooling process can guide the product to form a crystal structure conducive to ion transport, further optimizing the ionic conductivity of the electrolyte.

[0052] (3) The crude halide solid electrolyte is pulverized and dried to obtain the halide solid electrolyte. Pulverization makes the product into a powder with uniform particle size, increasing the specific surface area, which facilitates full contact with the electrode material in the subsequent solid-state battery preparation process and reduces the interfacial resistance. Drying removes trace amounts of moisture that may be introduced during the melting reaction and subsequent operations, avoiding electrolyte hydrolysis and ionic conductivity decay caused by moisture, and ensuring the performance stability of the final product.

[0053] According to the technical solution of the present invention, the main components are a mixture of LiCl, LiBr, and LiI, wherein, based on the total weight of LiCl, LiBr, and LiI as 100%, LiCl accounts for 40-60%, LiBr accounts for 20-35%, and LiI accounts for 15-30%. This invention overcomes the limitation of using a single lithium-based halide as the main component in existing technologies, employing a compounding of three lithium halides to optimize the ion transport channel by utilizing the structural complementarity of the three halides. LiCl possesses good chemical stability and structural regularity, providing a stable crystal framework for the electrolyte; LiBr has a moderate ion migration barrier, which can improve the ion transport rate; LiI has a low lattice energy, effectively increasing the lithium ion concentration and mobility in the electrolyte. If the proportion of LiCl exceeds 60%, the electrolyte lattice energy will be too high, increasing the resistance to lithium ion migration and decreasing the ionic conductivity; if the proportion of LiCl is less than 40%, the crystal framework stability of the electrolyte will be insufficient, and the humidity stability and mechanical properties will deteriorate. If the LiBr content exceeds the range of 20-35%, it will disrupt the synergistic effect of the three halides, leading to distortion of the ion transport channels. If the LiI content is higher than 30%, the overall humidity stability of the electrolyte will decrease due to the strong hygroscopicity of LiI; if it is lower than 15%, it cannot fully exert its function of reducing lattice energy and improving ion mobility. A mixture of 40-60% LiCl, 20-35% LiBr, and 15-30% LiI can achieve the optimal balance between crystal framework stability, ion migration rate, and humidity stability, providing an excellent basic support for subsequent doping and modification.

[0054] The rare earth element dopant is a mixture of Y₂O₃ and La₂O₃. The ionic radii of rare earth elements differ from those of lithium ions. After doping, they can form appropriate lattice defects in the crystal lattice of the main component. These defects act as "vacancies" for lithium ion transport, effectively reducing the migration barrier of lithium ions and improving ionic conductivity. Simultaneously, both Y₂O₃ and La₂O₃ possess good chemical and oxidation stability, which can improve the electrochemical window of the electrolyte and prevent oxidative decomposition of the electrolyte under high voltage. The use of a mixture of Y₂O₃ and La₂O₃, rather than a single rare earth oxide, is because their different ionic radii allow for the formation of different types and sizes of lattice defects, constructing multi-level ion transport channels and further improving ion transport efficiency. If only a single rare earth oxide is used, the lattice defect types are limited, the optimization effect of the ion transport channels is limited, and it is difficult to achieve a significant increase in ionic conductivity.

[0055] The transition metal dopants are a mixture of ZrCl4 and HfCl4. Zr 4+ With Hf 4+With high valence and stable electronic structure, these substances, after doping, can form strong coordination bonds with halide ions in the main component, enhancing the stability of the electrolyte crystal structure. Simultaneously, they can effectively suppress the localized aggregation of lithium ions and promote uniform lithium ion migration. Furthermore, the introduction of ZrCl4 and HfCl4 can improve the compatibility of the electrolyte with high-voltage cathode materials, reduce interfacial charge transfer resistance, and improve the cycle performance of solid-state batteries. The combined use of these two substances leverages the complementarity of their electronic structures to further enhance their stabilizing effect on the crystal structure and their promoting effect on lithium ion migration; the doping effect of a single transition metal halide is far less than that of the combined effect.

[0056] The main group metal dopants are a mixture of Al₂O₃ and Ga₂O₃. Al 3+ with Ga 3+ The small ionic radius of Al₂O₃ allows it to disperse uniformly within the interstitial lattice of the main components. This not only refines lattice defects and optimizes ion transport channels but also forms a dense oxide protective film on the electrolyte surface, inhibiting reactions between the electrolyte and moisture and oxygen in the air, thus significantly improving the electrolyte's humidity stability. Simultaneously, both Al₂O₃ and Ga₂O₃ are insulating materials; their introduction does not increase the electrolyte's electronic conductivity, ensuring that the electrolyte meets the insulation requirements of solid-state batteries and preventing self-discharge and safety hazards. The combination of these two materials achieves a dual synergistic optimization of lattice defect refinement and surface protection, effects that are difficult to maximize simultaneously with a single main group metal oxide.

[0057] The inorganic modifier is selected from one or more of Li₂SO₄, Li₃PO₄, and Li₂CO₃. The introduction of the inorganic modifier can synergistically interact with the main components and dopants to further optimize the electrolyte performance. The sulfate and phosphate ions in Li₂SO₄ and Li₃PO₄ have strong coordination capabilities, forming weak coordination bonds with lithium ions, reducing the migration resistance of lithium ions, and enhancing the mechanical properties of the electrolyte. Li₂CO₃ can neutralize trace acidic impurities that may be present in the electrolyte, improving the chemical stability of the electrolyte, and simultaneously forming a lithium carbonate protective layer on the electrolyte surface, further improving humidity stability. This invention allows for the selection of single or multiple inorganic modifiers in combination according to actual performance requirements; when used in combination, multiple performance enhancements can be achieved.

[0058] The organic modifier is selected from one or more of polymethyl methacrylate (PMMA), polyethylene glycol (PEG), and polyvinylidene fluoride (PVDF). As a polymer material, the organic modifier improves the mechanical plasticity of the electrolyte, transforming it from brittle to tough, thus falling into the category of soft electrolytes. It can form a high-density structure through cold pressing, eliminating the need for high-temperature sintering and significantly reducing the difficulty of solid-state battery fabrication. Simultaneously, the presence of polymer chains can form connections between electrolyte particles, improving the film-forming properties of the electrolyte and facilitating the preparation of thin and uniform solid electrolyte layers. Furthermore, the organic modifier can reduce the interfacial tension between the electrolyte and the positive and negative electrode materials, improving interfacial contact and reducing interfacial resistance. PMMA, PEG, and PVDF each have their own molecular structures and properties, and can be used individually or in combination according to actual needs to optimize mechanical properties, film-forming properties, and interfacial compatibility. Under an inert atmosphere, the organic modifier melts at the melting temperature and may even partially decompose. However, its decomposition products (such as amorphous carbon) form a uniform composite interface layer with the inorganic components. This interface layer helps to improve the flexibility and interfacial compatibility of the electrolyte.

[0059] Based on the total weight of the main component, rare earth element dopants, transition metal element dopants, main group metal element dopants, inorganic modifiers, and organic modifiers as 100%, the main component accounts for 70-85%, rare earth element dopants account for 2-10%, transition metal element dopants account for 2-10%, main group metal element dopants account for 1-5%, inorganic modifiers account for 0.5-6%, and organic modifiers account for 0.5-4%. This proportion limit is the basis for the synergistic effect of the multi-components in this invention. As the core carrier of the electrolyte, the main component needs to maintain a proportion of 70-85%. If the proportion is too low, the concentration of each dopant and modifier will be too high, leading to the formation of impurity phases, disordered crystal structure, and a significant decrease in ionic conductivity and stability. If the proportion is too high, the amount of dopant and modifier will be insufficient, and their modification effect cannot be fully utilized, resulting in limited performance improvement of the electrolyte. The proportions of rare earth element dopants and transition metal element dopants are both 2-10%. This range ensures sufficient lattice defects to improve ionic conductivity while avoiding lattice distortion and impurity phase formation caused by excessive doping. If the doping amount is below 2%, there are insufficient lattice defects, and the modification effect is not obvious. If it is above 10%, it will destroy the crystal structure of the main component, leading to obstruction of ion transport channels and a decrease in ionic conductivity. The proportion of main group metal element dopants is 1-5%. A small amount of main group metal oxides can achieve the effects of lattice defect refinement and surface protection. If the proportion is too high, it will lead to an increase in the lattice energy of the electrolyte and a decrease in ionic conductivity. Inorganic modifiers account for 0.5-6%, and organic modifiers account for 0.5-4%. Both are low proportions, and only a small amount is needed to optimize mechanical properties, humidity stability, and interfacial compatibility. If the proportion is too high, it will dilute the concentration of the main component and reduce ionic conductivity. At the same time, an excessive proportion of organic modifiers will also lead to an increase in the electronic conductivity of the electrolyte, bringing the risk of self-discharge.

[0060] According to certain preferred embodiments of the present invention, the rare earth element dopant is a mixture of Y₂O₃ and La₂O₃ in a weight ratio of 3:1 to 5:1. Experimental verification has shown that a weight ratio of 3:1 to 5:1 is the optimal range for the synergistic effect of the two elements. At this ratio, the type and number of lattice defects formed by Y₂O₃ and La₂O₃ are most suitable for lithium-ion transport, maximizing the improvement of ionic conductivity and electrochemical window.

[0061] According to certain preferred embodiments of the present invention, the transition metal dopant is a mixture of ZrCl4 and HfCl4 in a weight ratio of 2:1 to 4:1. This 2:1 to 4:1 weight ratio allows ZrCl4 to... 4+ With Hf 4+ The electrolyte is uniformly dispersed in the lattice of the main components, giving full play to its role in stabilizing the crystal structure and promoting the uniform migration of lithium ions, while optimizing the compatibility between the electrolyte and the high-voltage cathode material.

[0062] According to certain preferred embodiments of the present invention, the main group metal element dopant is a mixture of Al₂O₃ and Ga₂O₃ in a weight ratio of 1:1 to 2:1. This 1:1 to 2:1 weight ratio maximizes the dual effects of lattice defect refinement and surface protective film formation. The appropriate introduction of Al₂O₃ and Ga₂O₃ effectively refines lattice defects, and the combination of the two in this ratio synergistically enhances the ionic conductivity and humidity stability of the electrolyte.

[0063] According to certain preferred embodiments of the present invention, the inorganic modifier is a mixture of Li₂SO₄ and Li₃PO₄ in a weight ratio of 1:1 to 3:1. The synergistic effect of Li₂SO₄ and Li₃PO₄ is optimal at this weight ratio, and the coordination abilities of sulfate and phosphate are complementary, which can minimize the migration resistance of lithium ions. At the same time, the combination of the two can significantly improve the mechanical properties and chemical stability of the electrolyte.

[0064] According to certain preferred embodiments of the present invention, the organic modifier is a mixture of polymethyl methacrylate (PMMA) and polyethylene glycol (PEG) in a weight ratio of 2:1 to 5:1. PMMA has good mechanical properties and film-forming properties, while PEG has a low glass transition temperature and good lithium-ion compatibility. The combination of the two in a weight ratio of 2:1 to 5:1 achieves an optimal balance between the mechanical plasticity and ion transport properties of the electrolyte. PMMA as the main component ensures the mechanical strength of the electrolyte, while the appropriate introduction of PEG can lower the glass transition temperature of the electrolyte, improve its flexibility, and simultaneously promote lithium-ion migration.

[0065] According to certain preferred embodiments of the present invention, the polymethyl methacrylate (PMMA) has a weight-average molecular weight in the range of 10,000-100,000 Da and an average particle size in the range of 50-80 μm. Weight-average molecular weight and average particle size are key parameters affecting the performance of PMMA; a weight-average molecular weight of 10,000-100,000 Da ensures that PMMA possesses good mechanical properties.

[0066] According to certain preferred embodiments of the present invention, the polyethylene glycol has a weight-average molecular weight in the range of 2000-8000 Da and an average particle size in the range of 1-10 μm. PEG with a weight-average molecular weight of 2000-8000 Da has moderate viscosity and lithium-ion conductivity, which can improve the flexibility of the electrolyte without excessively hindering the migration of lithium ions.

[0067] According to certain preferred embodiments of the present invention, the polyvinylidene fluoride has a weight-average molecular weight in the range of 100,000-300,000 Da and an average particle size in the range of 1-50 μm. PVDF with a weight-average molecular weight of 100,000-300,000 Da has excellent mechanical properties, chemical stability, and film-forming properties, and can provide good mechanical support and chemical stability for electrolytes.

[0068] According to certain preferred embodiments of the present invention, the preparation method further includes, before step (1): drying and pulverizing the main component, rare earth element dopant, transition metal element dopant, main group metal element dopant, and inorganic modifier separately under an inert atmosphere. Raw materials are prone to adsorbing trace amounts of moisture during storage and transportation, and some raw materials exhibit particle agglomeration. Direct mixing can lead to uneven mixing and moisture-induced hydrolysis. Therefore, separate drying and pulverizing pretreatment of the above-mentioned inorganic raw materials is an important prerequisite for ensuring the uniformity of subsequent mixing and the stability of product performance. Organic modifiers, due to their weak hygroscopicity, can be used directly or after simple drying.

[0069] Furthermore, the drying is carried out for 8-12 hours under conditions of vacuum degree ≤10Pa and temperature 80-120°C. The pulverization is carried out by a planetary ball mill with a ball milling speed of 200-300 r / min, a ball milling time of 2-4 hours, and a ball-to-material ratio of 10:1-15:1.

[0070] According to certain preferred embodiments of the present invention, in step (1), the mixing includes: first, premixing the main components, then adding rare earth element dopants, transition metal element dopants, and main group metal element dopants for mixing, and finally adding inorganic modifiers and organic modifiers for mixing. The present invention adopts a step-by-step mixing method, rather than mixing all raw materials at once. This is a process optimization based on the differences in the properties of each component, which can maximize the uniformity of the mixing. The main components, as the core carrier, are premixed to ensure that the three lithium halides are fully integrated to form a uniform basic system; then, the three types of dopants are added to ensure that the dopants are uniformly dispersed in the basic system of the main components, achieving microscopic uniform contact between the dopants and the main components; finally, the inorganic and organic modifiers are added to avoid molecular chain breakage of the organic modifier due to excessive shear force in the early mixing stage, while ensuring that the inorganic and organic modifiers are uniformly dispersed in the formed main-dopant system, achieving comprehensive coverage of the modification effect. Each step of the step-by-step mixing process can be carried out using a planetary ball mill. The ball milling parameters can be adjusted appropriately according to the mixing stage to ensure the mixing effect while avoiding excessive wear of the raw materials and structural damage to the organic modifier.

[0071] According to certain preferred embodiments of the present invention, in step (2), the heating rate is 5-10°C / min.

[0072] According to certain preferred embodiments of the present invention, in step (2), the cooling rate is 3-5°C / min. The cooling rate is an important parameter affecting the crystal structure of the product. Slow cooling of 3-5°C / min can promote the formation of a crystal structure with a regular lattice structure that is conducive to lithium-ion transport, while avoiding problems such as excessive internal stress in the crystal structure, too many crystal defects, or even cracking caused by excessive cooling.

[0073] According to certain preferred embodiments of the present invention, in step (3), the pulverization is carried out by a planetary ball mill with a ball milling speed of 250-300 r / min, a ball milling time of 2-3 hours, and a ball-to-material ratio of 12:1-15:1.

[0074] According to another aspect of the present invention, a halide solid electrolyte is provided, which is prepared according to the method described above. Due to the precise synergistic design of raw material components and the optimization of the preparation process, the halide solid electrolyte of the present invention achieves a synergistic improvement in ionic conductivity, electrochemical window, humidity stability, and mechanical properties. Its performance indicators are superior to those of existing halide solid electrolytes, effectively addressing the performance shortcomings of existing technologies and meeting the application requirements of all-solid-state batteries.

[0075] According to certain preferred embodiments of the present invention, the room temperature ionic conductivity of the halide solid electrolyte is 2.6-5.0 mS•cm. -1 This invention achieves a room-temperature ionic conductivity higher than existing oxide solid electrolytes, comparable to sulfide solid electrolytes, and higher than traditional single halide or simply doped halide solid electrolytes, thus meeting the ion transport rate requirements of high-power-density all-solid-state batteries. By constructing a multi-level ion transport channel through lithium-based halide compounding and a ternary composite doping system, this invention effectively reduces the lithium-ion migration barrier, achieving a significant increase in ionic conductivity. Furthermore, the electrolyte exhibits extremely low electronic conductivity, avoiding self-discharge and safety hazards.

[0076] According to certain preferred embodiments of the present invention, the electrochemical window of the halide solid electrolyte is 0-5.2V (vs. Li / Li). +This wide electrochemical window is one of the advantages of this invention. It is highly compatible with next-generation high-voltage cathode materials such as lithium-rich manganese-based and high-nickel ternary materials, preventing the electrolyte from undergoing oxidative decomposition at high voltages and effectively improving the energy density and cycle life of solid-state batteries. Existing halide solid-state electrolytes typically have electrochemical windows below 4.5 V, making them difficult to match with high-voltage cathode materials. This invention, through the composite doping of rare earth elements and transition metal elements, improves the oxidation stability of the electrolyte, extending the electrochemical window to 5.2 V, thus making the fabrication of high-energy-density all-solid-state batteries possible.

[0077] According to certain preferred embodiments of the present invention, after exposure to an environment with a humidity of 5-10% for 72 hours, the ionic conductivity retention rate of the halide solid electrolyte is greater than or equal to 87%. Poor humidity stability is one of the main technical bottlenecks of existing halide solid electrolytes. Most halides are prone to hydrolysis in humid environments, generating impurities, which leads to a sharp decline in ionic conductivity. However, the halide solid electrolyte of the present invention enhances chemical stability through doping with main group metal oxides and introducing inorganic modifiers, while optimizing the composition ratio of the main components to reduce hygroscopicity, thus significantly improving humidity stability.

[0078] According to certain preferred embodiments of the present invention, the Young's modulus of the halide solid electrolyte is 1.8-2.2 GPa. This Young's modulus range indicates that the electrolyte of the present invention belongs to the category of soft electrolytes, possessing both good mechanical strength and plasticity. It can form a high-density structure through cold pressing without the need for high-temperature sintering, significantly reducing the complexity and energy consumption of solid-state battery manufacturing processes. Simultaneously, the good mechanical plasticity allows the electrolyte to achieve close interfacial contact with the positive and negative electrode materials, effectively reducing interfacial resistance and improving interfacial compatibility. The mechanical strength of 1.8-2.2 GPa ensures that the electrolyte will not crack or break during battery assembly and cycling, guaranteeing the structural stability and cycle performance of the battery. Existing halide solid electrolytes often suffer from high mechanical brittleness or insufficient mechanical strength. The present invention achieves an optimal balance between mechanical strength and plasticity through the introduction of an organic-inorganic composite modifier.

[0079] According to another aspect of the present invention, a solid-state battery for new energy vehicles is provided. The solid-state battery includes a positive electrode, a negative electrode, a solid electrolyte layer, and a casing. The solid electrolyte layer is prepared from the halide solid electrolyte described above. The solid-state battery of the present invention, by employing the aforementioned high-performance halide solid electrolyte, eliminates the need for traditional liquid electrolytes, thus solving the safety hazards of liquid lithium-ion batteries such as flammability, explosion, and leakage. Simultaneously, the high ionic conductivity, wide electrochemical window, good humidity stability, and interfacial compatibility of the electrolyte significantly improve the energy density, cycle life, safety performance, and environmental adaptability of the solid-state battery.

[0080] According to certain preferred embodiments of the present invention, the thickness of the solid electrolyte layer is 10-50 μm. The halide solid electrolyte of the present invention, due to its good mechanical plasticity, can be prepared into a thin and uniform solid electrolyte layer of 10-50 μm through processes such as cold pressing, meeting the requirements of high energy density and high power density solid-state batteries.

[0081] According to certain preferred embodiments of the present invention, the positive electrode comprises a positive electrode active material, a conductive agent, and the halide solid electrolyte. The present invention employs a composite positive electrode structure, introducing the halide solid electrolyte into the positive electrode to form a ternary composite system of positive electrode active material-conductive agent-solid electrolyte, which effectively solves the interfacial contact problem between the positive electrode and the solid electrolyte layer, reducing interfacial resistance. The solid electrolyte forms continuous ion transport channels inside the positive electrode, enabling lithium ions to migrate rapidly between the positive electrode active material and the electrolyte layer, improving the rate performance and cycle performance of the battery; simultaneously, the good compatibility between the halide solid electrolyte and the positive electrode active material avoids interfacial side reactions, improving the structural stability of the positive electrode.

[0082] Furthermore, based on the weight of the positive electrode as 100%, the content of the positive electrode active material is 65-75%, the content of the conductive agent is 8-10%, and the content of the halide solid electrolyte is 15-25%.

[0083] According to certain preferred embodiments of the present invention, an interface modification layer is provided on the surface of the negative electrode, the interface modification layer comprising the halide solid electrolyte and metal alloy powder. The interfacial compatibility between the negative electrode and the solid electrolyte layer is one of the key factors affecting the performance of solid-state batteries. When a lithium metal negative electrode comes into contact with a traditional solid electrolyte, lithium dendrites easily form. The growth of lithium dendrites can pierce the electrolyte layer, leading to a short circuit in the battery. Simultaneously, side reactions easily occur at the interface, forming a solid electrolyte interphase (SEI film). If the SEI film is unstable, the interfacial resistance will continuously increase, and the battery cycle life will decrease. According to certain preferred embodiments of the present invention, by providing an interface modification layer on the surface of the negative electrode, the good compatibility between the halide solid electrolyte and the negative electrode and metal alloy powder is utilized to form a stable, dense, and highly ion-conducting interfacial layer. This can suppress the growth of lithium dendrites, reduce interfacial side reactions, lower interfacial resistance, and improve the cycle performance and safety performance of the battery.

[0084] According to certain preferred embodiments of the present invention, the metal alloy powder is selected from at least one of lithium-based alloys or sodium-based alloys. Lithium-based alloys and sodium-based alloys possess good lithium-ion conductivity and chemical stability, and can synergistically interact with halide solid electrolytes to optimize the ion transport channels at the interface. Simultaneously, the presence of the alloy powder can inhibit the nucleation and growth of lithium dendrites, improving the structural stability of the anode. Further, the lithium-based alloy is selected from at least one of Li-In alloys or Li-Sn alloys, and the sodium-based alloy is a Na-Sn alloy. Li-In alloys, Li-Sn alloys, and Na-Sn alloys are all low-melting-point alloys, capable of forming a uniform interface modification layer with the halide solid electrolyte. Furthermore, they have a high lithium-ion diffusion coefficient, which can improve the ion transport efficiency at the interface. At the same time, these alloys have good compatibility with the lithium metal anode, without significant side reactions, ensuring the stability of the interface modification layer.

[0085] According to certain preferred embodiments of the present invention, the content of the halide solid electrolyte is 75-80% and the content of the metal alloy powder is 20-25% based on 100% by weight of the interface modification layer. This ratio achieves the best balance between the ion conductivity of the interface modification layer and the lithium dendrite suppression effect.

[0086] The present invention will now be described in more detail with reference to embodiments. It should be noted that these descriptions and embodiments are intended to facilitate understanding of the present invention and are not intended to limit the invention.

[0087] Example In this invention, unless otherwise specified, all reagents used are commercially available products and are used directly without further purification. Furthermore, "%" refers to "weight %" and "parts" refers to "parts by weight".

[0088] Table 1 below lists specific information about the raw materials used in the embodiments and comparative examples of the present invention.

[0089] Table 1 List of Experimental Materials Table 2 below lists specific information about the experimental equipment used in the embodiments and comparative examples of the present invention.

[0090] Table 2 List of Experimental Equipment Performance testing methods (I) Room temperature ionic conductivity test The room temperature ionic conductivity of halide solid electrolyte samples prepared in the following examples and comparative examples was tested according to the methods described below.

[0091] Referring to the national standard GB / T 39864-2021 "Test Method for Ionic Conductivity of Solid Electrolytes", the AC impedance spectroscopy method was used for testing. The specific steps are as follows: The prepared halide solid electrolyte powder was pressed into a disc with a diameter of 14 mm and a thickness of 0.8 ± 0.1 mm under a pressure of 20 MPa. Surface impurities were removed in an argon glove box, and the disc thickness L was accurately measured (accurate to 0.1 μm). The electrolyte disc was clamped between two polished stainless steel blocking electrodes to assemble a symmetrical cell of stainless steel blocking electrode (SS) / electrolyte / stainless steel blocking electrode (SS). Using an electrochemical workstation at room temperature of 25°C, with a frequency range of 1 Hz-1 MHz and an AC signal amplitude of 10 mV, the Nyquist impedance spectrum was obtained, and the bulk resistance R at the intersection of the high-frequency region and the real axis was read. The ionic conductivity (σ; unit mS•cm) was calculated using the formula σ = L / (R×A). -1 (), where A is the effective contact area of ​​the electrode. Each group of samples was tested in parallel three times, and the average value was taken as the final result.

[0092] (II) Electrochemical stability window test Electrochemical stability window tests were performed on halide solid electrolyte samples prepared in the following examples and comparative examples according to the methods described below.

[0093] Specifically, referring to the relevant electrochemical performance testing specifications in the national standard GB / T 39864-2021 "Test Method for Ionic Conductivity of Solid Electrolytes", linear sweep voltammetry (LSV) was used for measurement. The specific steps are as follows: The prepared halide solid electrolyte powder was pressed into circular discs with a diameter of 14 mm and a thickness of 0.8 ± 0.1 mm under a pressure of 20 MPa. The surface was cleaned and the thickness was measured in an argon glove box. Lithium metal foil was used as the counter electrode and reference electrode (Li / Li). + Stainless steel was used as the working electrode, and a stainless steel blocked electrode (SS) / halide solid electrolyte / Li half-cell was assembled. Then, the electrochemical workstation was started, and at 25°C, the scan range was set to 0-6V (vs. Li / Li). + A linear sweep voltammetry test was performed at a scan rate of 1 mV / s, and the current-voltage (IV) curve was recorded. When the current density reached 10 μA / cm², the test was continued. 2 The voltage value corresponding to the time is the upper limit of the electrochemical window. The test results are expressed as 0 - the corresponding upper limit voltage (unit: V). The average value is taken from 3 parallel tests.

[0094] (III) Humidity stability retention rate test The humidity stability retention rate of halide solid electrolyte samples prepared in the following examples and comparative examples was tested according to the method described below.

[0095] The AC impedance method was used for testing according to the national standard GB / T 39864-2021 "Test Method for Ionic Conductivity of Solid Electrolytes". Specifically, the prepared halide solid electrolyte powder was pressed into discs with a diameter of 14 mm and a thickness of 0.8 ± 0.1 mm under a pressure of 20 MPa. Then, the electrolyte discs were stored in an argon glove box at 25°C and a humidity ≤ 1% RH for 24 hours, and the initial room temperature ionic conductivity σ0 was measured. Subsequently, the samples were placed in a constant temperature and humidity chamber, with the temperature set at 25°C and the relative humidity at 8 ± 2% RH (within the range of 5-10% RH), for continuous exposure for 72 hours, during which temperature and humidity were recorded every 24 hours. Within 30 minutes after the exposure ended, the samples were transferred to a glove box for cleaning and the room temperature ionic conductivity σt was measured again.

[0096] Calculate the humidity stability retention rate using the following formula: Retention rate (%) = (σt / σ0) × 100% Each group of samples was tested in parallel three times, and the average value was taken as the final result. A retention rate of ≥80% was considered to meet the basic stability requirements, and a retention rate of ≥85% was considered to have excellent humidity stability.

[0097] (iv) Young's modulus test Referring to the national standard GB / T 24179-2009 "Test Method for Nanoindentation of Metallic Materials", a nanoindentation instrument was used for testing. Before testing, the prepared halide solid electrolyte powder was pressed into a dense thin sheet (thickness 1.0±0.1mm) under a pressure of 20MPa. After polishing, a smooth and scratch-free test surface was obtained, and then placed in an argon glove box for later use. The test was conducted at room temperature of 25°C, using a Berkovich triangular indenter, with a loading rate set to 0.05mN / s and a maximum indentation depth of 500nm. During the test, the indenter was pressed vertically into the sample surface, and the instrument recorded the load-depth change curve in real time. Using the built-in analysis software, the Young's modulus value of the indented region was calculated based on Hooke's law and nanoindentation theory. Ten test points were selected at different locations on the sample. After removing the extreme values ​​in the test results, the arithmetic mean was taken as the final Young's modulus result of the sample. The test result is expressed in GPa.

[0098] Example 1 (E1) In this embodiment, except for the vacuum drying step, all operations are performed under an argon inert atmosphere (including raw material weighing, mixing, ball milling, melt reaction loading, and post-reaction processing). During vacuum drying, the material is sealed and transferred to the vacuum drying chamber under argon protection, and then removed in an argon atmosphere after drying. The specific steps are as follows: (1) Raw material pretreatment: The main components LiCl, LiBr, and LiI, rare earth element dopants Y₂O₃ and La₂O₃, transition metal element dopants ZrCl₄ and HfCl₄, main group metal element dopants Al₂O₃ and Ga₂O₃, and inorganic modifier Li₂SO₄ were weighed separately and placed in a vacuum drying oven. They were dried for 12 hours at a vacuum degree ≤10 Pa and a temperature of 80°C. After drying, each raw material was separately added to a planetary ball mill and ball-milled for 4 hours at 200 r / min using zirconium oxide as grinding balls at a ball-to-material ratio of 10:1 to obtain fine powders for later use. The organic modifier polymethyl methacrylate was used after drying.

[0099] (2) Mixed milling: As shown in Table 3 below, the raw materials were weighed according to their weight percentages, with a total weight of 100g. The composition was as follows: main component 70% by weight (LiCl 40% by weight, LiBr 35% by weight, LiI 25% by weight, based on the total weight of the main component), rare earth element dopant 10% by weight (Y₂O₃:La₂O₃=2:1), transition metal element dopant 10% by weight (ZrCl₄:HfCl₄=1:1), main group metal element dopant 5% by weight (Al₂O₃:Ga₂O₃=3:1), inorganic modifier 3% by weight, and organic modifier 2% by weight. The main component fine powder was first pre-mixed in a planetary ball mill for 1 hour. Then, the rare earth element dopant, transition metal element dopant, and main group metal element dopant were added and mixed for 2 hours. Finally, the inorganic and organic modifiers were added, and the mixture was ball-milled for another hour to obtain a mixed powder.

[0100] (3) Melting reaction: The mixed powder was transferred to an alumina crucible, placed in a tube furnace, and heated to 450°C at a heating rate of 5°C / min. The temperature was maintained for 8 hours to carry out the melting reaction. After the reaction was completed, the temperature was cooled to room temperature at a cooling rate of 3°C / min to obtain crude halide solid electrolyte.

[0101] (4) Grinding and drying: The crude halide solid electrolyte was added to a planetary ball mill at a ball-to-material ratio of 12:1 and a speed of 250 r / min for 3 hours. The pulverized powder was then placed in a vacuum drying oven and dried for 6 hours under a vacuum of ≤10 Pa and a temperature of 60°C to obtain halide solid electrolyte powder 1.

[0102] The halide solid electrolyte powder 1 was tested according to the test methods described above for room temperature ionic conductivity, electrochemical stability window, humidity stability retention and mechanical properties (Young's modulus), and the test results are shown in Table 4 below.

[0103] Figure 2 A scanning electron microscope (SEM) image of the halide solid electrolyte prepared in Example 1 is shown. Figure 2 As shown, the prepared halide solid electrolyte powder exhibits a uniform particle distribution.

[0104] Examples 2-13 (E2-E12) and Comparative Examples 1-5 (CE1-CE5) Examples 2-13 (E2-E13) and Comparative Examples 1-5 (CE1-CE5) were prepared in a manner similar to that of Example 1 to prepare halide solid electrolyte powders 2-13 and comparative halide solid electrolyte powders 1-5, the only difference being that the component types and ratios were changed as shown in Table 3 below.

[0105] The halide solid electrolyte powders 2-13 and comparative halide solid electrolyte powders 1-5 were tested according to the test methods described above for room temperature ionic conductivity, electrochemical stability window, humidity stability retention and mechanical properties (Young's modulus), and the results are shown in Table 4 below.

[0106] Table 3. Formulations and process parameters for Examples 1-13 (E1-E13) and Comparative Examples 1-5 (CE1-CE5) Table 4 Performance test results of Examples 1-13 (E1-E13) and Comparative Examples 1-5 (CE1-CE5) As can be seen from the performance test results of Examples 1-13 and Comparative Examples 1-5 in Table 4, the halide solid electrolyte prepared by the present invention exhibits significant advantages in all important performance aspects. However, the performance of the comparative examples that lack the dopant types and ratios specified by the present invention or do not use a composite doping system shows a significant decline, which verifies the superiority of the component design of the present invention.

[0107] Specifically, regarding room temperature ionic conductivity, the ionic conductivity of Examples 1-13 all ranged from 2.6 to 4.9 mS•cm. -1 Within this range, it is much higher than the 1.1-2.0 mS•cm of Comparative Examples 1-5. -1 Comparative Example 3, which did not contain any main group metal dopants, had the lowest conductivity, at only 1.1 mS•cm. -1 The conductivity of Example 13, which uses the preferred formulation of the present invention, reaches 4.9 mS•cm. -1The improvement is more than 3 times. This indicates that the ternary composite doping system of rare earth, transition metals and main group metals can effectively optimize the ion transport channels of electrolytes. Single doping will lead to a significant decrease in ion transport efficiency, while when the dopants are compounded according to the preferred weight ratio of this invention, the ionic conductivity can be maximized.

[0108] Regarding the electrochemical window performance, the electrochemical window of Examples 1-13 is 0 to 4.7-5.2 V (vs. Li / Li). + The electrochemical window of Comparative Examples 1-5 can reach up to 0-5.2 V, which can be matched with high-voltage cathode materials; while the electrochemical window of Comparative Examples 1-5 is only 0 to 3.8-4.2 V, which cannot meet the application requirements of high-energy-density batteries. The upper limit of the electrochemical window of Comparative Example 1, which lacks rare earth element dopants, and Comparative Example 2, which lacks transition metal dopants, is no higher than 4.0 V, which proves that the composite doping system can effectively improve the oxidation stability of the electrolyte and avoid decomposition reaction under high voltage. The electrochemical windows of Comparative Examples 4 and 5, which are doped with single oxides, are also much lower than those of the examples, which reflects the necessity of the dopant ratio design of the present invention.

[0109] Regarding humidity stability retention, the retention rates of Examples 1-13 were all ≥87%, with Example 13, using the preferred formulation, reaching 97%. In contrast, the retention rates of Comparative Examples 1-5 were only 62%-75%, failing to meet the basic stability requirements. Among them, Comparative Example 3, which did not contain any main group metal dopants, had the lowest retention rate at only 62%, indicating that the synergistic effect of ternary composite doping and inorganic-organic modifiers can effectively inhibit the hydrolysis reaction of halides and improve the air stability of the electrolyte.

[0110] Young's modulus is an important indicator for evaluating mechanical properties. The Young's modulus of Examples 1-13 is 1.8-2.2 GPa, falling within the category of soft electrolytes, allowing for the formation of a dense structure through cold pressing. In contrast, the Young's modulus of Comparative Examples 1-5 is only 1.1-1.5 GPa, indicating insufficient mechanical strength and a tendency to crack during battery assembly and cycling, leading to increased interfacial resistance. This result verifies that the component design of this invention can improve ion transport performance while simultaneously maintaining excellent mechanical properties, achieving synergistic optimization of multiple performance characteristics.

[0111] In summary, this invention, through the synergistic design of a lithium-based halide composite host, a ternary composite doping system, and an inorganic-organic composite modifier, combined with an optimized melt preparation process, successfully achieved a comprehensive improvement in the ionic conductivity, electrochemical window, humidity stability, and mechanical properties of halide solid electrolytes. Systems deviating from the scope of this invention cannot achieve all these properties, fully demonstrating the inventiveness and practicality of the technical solution of this invention.

[0112] Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from the spirit and scope of this disclosure. Therefore, if such modifications and variations fall within the scope of this invention, this disclosure is also intended to include such modifications and variations.

Claims

1. A method for preparing a halide solid electrolyte, characterized in that... This includes the following steps: (1) Under an inert atmosphere, the main component, rare earth element dopants, transition metal element dopants, main group metal element dopants, inorganic modifiers and organic modifiers are mixed to obtain a mixed powder; (2) The mixed powder is heated to 450-600°C under an inert atmosphere for a melting reaction for 4-8 hours, and then cooled to room temperature to obtain crude halide solid electrolyte; (3) Under an inert atmosphere, the crude halide solid electrolyte is pulverized and dried to obtain the halide solid electrolyte, wherein: The main component is a mixture of LiCl, LiBr and LiI, wherein, based on the total weight of LiCl, LiBr and LiI as 100%, LiCl accounts for 40-60%, LiBr accounts for 20-35%, and LiI accounts for 15-30%. The rare earth element dopant is a mixture of Y₂O₃ and La₂O₃; The transition metal dopant is a mixture of ZrCl4 and HfCl4; The main group metal element dopant is a mixture of Al2O3 and Ga2O3; The inorganic modifier is selected from one or more of Li2SO4, Li3PO4, and Li2CO3; The organic modifier is selected from one or more of polymethyl methacrylate, polyethylene glycol, and polyvinylidene fluoride; and Based on the total weight of the main component, rare earth element dopants, transition metal element dopants, main group metal element dopants, inorganic modifiers, and organic modifiers as 100%, the main component accounts for 70-85%, rare earth element dopants account for 2-10%, transition metal element dopants account for 2-10%, main group metal element dopants account for 1-5%, inorganic modifiers account for 0.5-6%, and organic modifiers account for 0.5-4%.

2. The method for preparing halide solid electrolyte according to claim 1, characterized in that... The rare earth element dopant is a mixture of Y2O3 and La2O3 in a weight ratio of 3:1 to 5:

1.

3. The method for preparing halide solid electrolyte according to claim 1, characterized in that... The transition metal element dopant is a mixture of ZrCl4 and HfCl4 in a weight ratio of 2:1 to 4:

1.

4. The method for preparing halide solid electrolyte according to claim 1, characterized in that... The main group metal element dopant is a mixture of Al2O3 and Ga2O3 in a weight ratio of 1:1 to 2:

1.

5. The method for preparing a halide solid electrolyte according to claim 1, characterized in that... The inorganic modifier is a mixture of Li2SO4 and Li3PO4 in a weight ratio of 1:1 to 3:

1.

6. The method for preparing a halide solid electrolyte according to claim 1, characterized in that... The organic modifier is a mixture of polymethyl methacrylate and polyethylene glycol in a weight ratio of 2:1 to 5:

1.

7. The method for preparing a halide solid electrolyte according to claim 1, characterized in that... The preparation method further includes, before step (1): drying and pulverizing the main component, rare earth element dopant, transition metal element dopant, main group metal element dopant and inorganic modifier respectively under an inert atmosphere.

8. The method for preparing a halide solid electrolyte according to claim 7, characterized in that... The drying is carried out for 8-12 hours under conditions of vacuum degree ≤10Pa and temperature 80-120°C; the pulverization is carried out by a planetary ball mill with a ball milling speed of 200-300r / min, a ball milling time of 2-4 hours, and a ball-to-material ratio of 10:1-15:

1.

9. A halide solid electrolyte, characterized in that... The halide solid electrolyte is prepared by the method according to any one of claims 1-8.

10. A solid-state battery for new energy vehicles, characterized in that... The new energy vehicle solid-state battery includes a positive electrode, a negative electrode, a solid electrolyte layer, and a shell, wherein the solid electrolyte layer is prepared from the halide solid electrolyte according to claim 9.

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