Halide solid electrolyte material, preparation method thereof and lithium ion battery

Abstract

The chemical general formula of the electrolyte material is LiaMXbFc, M is Y or Gd, X is at least one of Cl and Br, a is more than or equal to 2.5 and less than or equal to 3, b is more than or equal to 5.4 and less than or equal to 5.99, and c is more than or equal to 0.01 and less than or equal to 0.1; the electrolyte material is in the form of powder particles, and the particle size D50 of the powder particles is smaller than or equal to 5 micrometers. The F element is distributed on the surfaces of powder particles, and the distribution depth is larger than or equal to 5 nm and smaller than or equal to 150 nm. By accurately controlling the particle size of electrolyte particles and the depth of a surface fluorination layer, high ionic conductivity is maintained, and meanwhile, the interface stability of the electrolyte and a high-voltage positive electrode and the cycle performance of the battery are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte materials technology, and particularly to a halide solid electrolyte material and its preparation method, and a lithium-ion battery. Background Technology

[0002] In recent years, the electric vehicle industry has developed rapidly. However, frequent safety incidents involving power batteries have also highlighted the critical importance of ensuring safety while increasing battery energy density. All-solid-state batteries, which use solid electrolytes instead of traditional liquid electrolytes, eliminate the risk of fire and explosion at its source, representing a significant future direction for power batteries. As a core component of all-solid-state batteries, solid electrolyte (SEs) materials largely determine key performance characteristics such as energy density, safety, temperature stability, and cycle life.

[0003] Currently, halide solid-state electrolytes still lag behind sulfide systems in terms of ionic conductivity. Although ionic conductivity can be increased to over 3 mS / cm through mixed halogen strategies (such as the development of materials like Li3YCl3Br3 and Li3GdCl3Br3), the introduction of Br also brings problems such as decreased cycle stability and limited energy density. Research has found that these problems mainly stem from two aspects: first, insufficient particle matching between the electrolyte and the cathode material leads to local current instability during charge and discharge, which in turn causes damage to the cathode structure; second, the introduction of Br reduces the oxidation potential of the electrolyte, making it difficult to match with high-voltage cathode active materials, thus limiting further improvements in the energy density of all-solid-state batteries. Summary of the Invention

[0004] The purpose of this invention is to provide a halide solid electrolyte material and its preparation method, as well as a lithium-ion battery. By limiting the particle size of the electrolyte powder and controlling the distribution depth of fluorine on the surface, this halide solid electrolyte material significantly improves compatibility with the high-voltage cathode and battery cycle stability while maintaining high ionic conductivity.

[0005] To address the aforementioned technical problems, a first aspect of this invention provides a halide solid electrolyte material, wherein the general chemical formula of the electrolyte material is Li. a MX b F c M is Y or Gd, X is at least one of Cl and Br, 2.5≤a≤3, 5.4≤b≤5.99, 0.01≤c≤0.1; The electrolyte material is in the form of powder particles, and the particle size D of the powder particles is... 50 ≤5μm; F element is distributed on the surface of powder particles at a depth of ≥5nm and ≤150nm.

[0006] Furthermore, the room temperature ionic conductivity of the electrolyte material is ≥3 mS / cm.

[0007] Furthermore, the particle size D of the electrolyte powder 50 ≤1μm.

[0008] Accordingly, a second aspect of the present invention provides a method for preparing a solid electrolyte material, used to prepare the above-mentioned halide solid electrolyte material, comprising the following steps: S1: Lithium halide and metal M halide are mixed and ground according to chemical formula ratio, and sintered at a first preset temperature in an environment isolated from water and oxygen to obtain the first reactant. S2: The first reactant is crushed to obtain a second reactant with a preset powder particle size; S3: After the second reactant is subjected to fluorination treatment by powder fluidization, it is then subjected to high-temperature annealing at a second preset temperature to obtain a powder granular electrolyte material.

[0009] Further, the fluorination treatment of the second reactant by powder fluidization includes: The second reactant is loaded into a fluidized bed protected by an inert gas. A mixed gas containing HF is introduced while the powder is in a fluidized state. After being treated at a third preset temperature for a first preset time, a high-temperature annealing treatment is performed.

[0010] Further, the mixed gas includes: a mixture of HF and N2 or a mixture of HF and Ar; The numerical range of the third preset temperature is 50℃~100℃; The first preset duration is 1 min to 20 min.

[0011] Furthermore, the water- and oxygen-isolated environment is a vacuum, argon, or nitrogen environment; The first preset temperature is 400℃~600℃; The second preset temperature is 200℃~300℃; The particle size D of the preset powder particle size 50 ≤5μm.

[0012] Accordingly, a third aspect of the present invention provides a lithium-ion battery, comprising: a positive electrode layer, a negative electrode layer, and an electrolyte layer located between the positive electrode layer and the negative electrode layer, wherein the electrolyte layer comprises the above-described halide solid electrolyte material or a halide solid electrolyte material prepared by the above-described halide solid electrolyte material preparation method.

[0013] Furthermore, the active material of the positive electrode layer has an operating voltage ≥ 4.4V.

[0014] Furthermore, the active material of the positive electrode layer is any one of NMC, LNMO, and lithium-rich manganese-based morphological oxides.

[0015] The above-described technical solutions of the embodiments of the present invention have the following beneficial technical effects: 1. By limiting the distribution of fluorine to a specific depth on the surface of the powder particles, the fluoride layer effectively passivates the electrolyte surface and improves its oxidation potential, thereby avoiding interface deterioration caused by electrolyte oxidation during charging and discharging. At the same time, the ultra-fine and uniform powder particle size ensures good matching and close contact with the positive electrode active material particles, effectively stabilizing the interfacial current distribution. Together, these factors enable the battery to maintain an extremely high capacity retention rate during long-term cycling. 2. By adopting fluidized bed fluorination, the fluorination reaction gas can be made into uniform and sufficient contact with the surface of electrolyte particles under mild conditions, realizing the controllable doping of fluorine in the shallow surface layer of particles; avoiding the destruction of the conductive main structure by the bulk fluorine, thus using fluorine to improve the interfacial stability while maximizing the preservation of the excellent high ionic conductivity of the material, achieving a unity of high ionic conductivity and high interfacial stability. 3. Particle size control and surface fluorination ensure a uniform ion / electron conduction network within the positive electrode layer and compatibility with the high-voltage positive electrode. This not only directly improves the battery's first-cycle discharge capacity but also fundamentally suppresses the degradation of the positive electrode interface under high voltage, enabling all-solid-state batteries using this electrolyte to exhibit both high energy density and ultra-long cycle life. Attached Figure Description

[0016] Figure 1 This is a flowchart of the method for preparing halide solid electrolyte materials provided in the embodiments of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0018] A first aspect of this invention provides a halide solid electrolyte material, wherein the general chemical formula of the electrolyte material is Li. a MX b F cM is Y or Gd, X is at least one of Cl and Br, 2.5≤a≤3, 5.4≤b≤5.99, 0.01≤c≤0.1; the electrolyte material is in the form of powder particles, and the particle size D of the powder particles is... 50 ≤5μm; F element is distributed on the surface of powder particles at a depth of ≥5nm and ≤150nm.

[0019] The fluorine (F) element on the particle surface hinders the transport of Li ions in the electrolyte. Therefore, if the F element distribution depth is too thick, such as ≥150 nm, the electrolyte's ionic conductivity will decrease significantly, damaging the original performance of the electrolyte. When the F element distribution depth is <5 nm, the desired effect cannot be achieved. When the fluorination depth is ≥5 nm and ≤150 nm, the fluorinated electrolyte not only maintains high ionic conductivity, but the prepared battery also exhibits better cycle stability and higher battery capacity.

[0020] This invention strictly limits the electrolyte material to a powder particle morphology and controls its particle size D. 50 With a particle size of ≤5μm, it ensures good matching with commonly used cathode active materials at the particle size, promotes the construction of a uniform and dense cathode layer, thereby improving interfacial ion transport and stabilizing local current distribution. At the same time, the distribution of F element is precisely controlled within a depth range of 5nm to 150nm on the powder particle surface. The excellent stability of F element is used to effectively passivate the electrolyte surface, suppress the side reactions at the interface with high-voltage cathode materials, and improve the overall oxidation stability. At the same time, it minimizes the obstruction of lithium-ion migration channels by bulk doping. This allows the material to maintain an ionic conductivity of over 3 mS / cm while also having excellent high-voltage cycle stability and higher battery energy density.

[0021] Preferably, the M element in the electrolyte chemical formula is Y or Gd, and the X element is Cl or Br, and the room temperature ionic conductivity of the electrolyte is ≥3 mS / cm.

[0022] The particle size of halide electrolytes has a significant impact on the electrochemical performance of batteries. Firstly, particle size directly affects the amount of contact surface between particles, influencing ionic conductivity. Secondly, particle size affects the particle contact matching between the electrolyte and the positive electrode active material, further impacting battery cycle life and capacity. Conventional positive electrode active material particle size D50 = 5 μm; therefore, an electrolyte particle size D50 ≤ 5 μm is required for proper matching. Ideally, the electrolyte powder particle size D50 ≤ 1 μm provides even better matching, specifically resulting in higher discharge capacity in the first week of battery operation.

[0023] Accordingly, please refer to Figure 1 A second aspect of the present invention provides a method for preparing a solid electrolyte material, which is used to prepare the above-mentioned halide solid electrolyte material, comprising the following steps: S1: Lithium halides and metal M halides are mixed and ground according to the chemical formula ratio, and sintered at a first preset temperature in an environment isolated from water and oxygen to obtain the first reactant.

[0024] Specifically, the first preset temperature is 400℃~600℃; the water and oxygen isolation environment is a vacuum, argon or nitrogen environment.

[0025] By combining lithium halides (such as LiCl, LiBr) with halides of metallic M (such as YCl3, GdBr3) according to the target chemical formula Li a MX b The raw materials are weighed and mixed in precise molar proportions to achieve uniform premixing at the molecular scale. Subsequently, a solid-state sintering reaction is carried out in a strictly water- and oxygen-free vacuum or inert gas (argon / nitrogen) environment within a first preset temperature range of 400°C to 600°C. The value of the first preset temperature is optimized to provide sufficient activation energy for the translattice diffusion of lithium ions and metal M ions, promoting a solid-state reaction and crystallization to form the desired halide matrix crystal structure, while avoiding material decomposition or localized melting due to excessively high temperatures. This results in a first reactant with uniform chemical composition and the desired crystalline phase.

[0026] S2: The first reactant is crushed to obtain a second reactant with a preset particle size.

[0027] Specifically, the preset particle size D of the powder particles 50 ≤5μm. The above particle size treatment methods can be ball milling, air jet milling, or sand milling.

[0028] The first reactant obtained from the S1 sintering step is typically a blocky or coarse-grained sintered body, whose particle size and distribution cannot meet the requirements of subsequent uniform fluorination and battery slurry processing. Therefore, mechanical crushing techniques (such as ball milling, air jet milling, or sand milling) are used to process it, breaking down large particles by applying mechanical force, and strictly controlling the particle size distribution characteristic parameter D50 of the final second reactant to below 3 micrometers. This particle size target ensures that the electrolyte powder and the positive electrode active material particles are size-matched, laying the physical foundation for constructing a composite positive electrode layer with a sufficient and dense solid-solid contact interface in subsequent battery fabrication. During the process, the particle size of the final powder can be precisely controlled by adjusting the operating parameters and duration of the crushing equipment. The longer the crushing time, the smaller the particle size D50 of the resulting product.

[0029] S3: After the second reactant is subjected to fluorination treatment by powder fluidization, it is then annealed at a second preset temperature to obtain a powder granular electrolyte material.

[0030] Specifically, the second preset temperature is 200℃~300℃; The second reactant, after particle size reduction, undergoes a controlled surface fluorination treatment in a fluidized bed reactor under inert gas protection. In the fluidized state, the powder particles are in full and uniform contact with a mixture containing dry HF gas, ensuring the homogeneity of the surface chemical reaction. This low-temperature (20°C–50°C) gas-phase treatment initiates a substitution reaction on the outer surface of the halide electrolyte particles, forming a fluorinated layer of controllable depth without significantly affecting the bulk structure of the material. Subsequently, annealing is performed at a second preset temperature of 200°C–300°C to eliminate lattice stresses that may be caused by the surface fluorination reaction and to make the formed surface fluorinated layer structure more dense and stable, ultimately obtaining a powder-like particulate electrolyte material with optimized surface properties and preserved bulk structure.

[0031] Furthermore, the second reactant is subjected to a fluorination treatment by powder fluidization, which includes: loading the second reactant into a fluidized bed protected by an inert gas, introducing a mixed gas containing HF gas in the powder fluidization state, treating it at a third preset temperature for a first preset time, and then performing a high-temperature annealing treatment.

[0032] Specifically, the gas mixture includes either a mixture of HF and N2 or a mixture of HF and Ar. The third preset temperature ranges from 50°C to 100°C; the first preset duration ranges from 1 minute to 20 minutes.

[0033] The second reactant, with particle size controlled, is loaded into the reactor and fluidized by an inert gas flow. This fluidization ensures that each powder particle is fully suspended, separated, and maximizes contact with the reactant gas. Subsequently, a mixture of active hydrogen fluoride gas and an inert carrier gas such as nitrogen or argon is introduced. The inert carrier gas acts not only as a diluent to precisely regulate the partial pressure of hydrogen fluoride but also as a medium to maintain stable powder fluidization and uniform heat transfer. The entire fluorination reaction is carried out under strictly controlled low-temperature conditions, with the third preset temperature range maintained between 20°C and 50°C. The first preset time is precisely controlled within the range of 1 minute to 20 minutes, confining the fluorination reaction primarily to the surface region of the powder particles. A thin, continuous fluorinated interface layer is formed through surface chemical replacement, while excessive penetration of the reactant gas into the bulk phase or damage to the matrix crystal structure is avoided. After this surface modification, the material undergoes a subsequent high-temperature annealing treatment to make the newly formed fluorinated layer structure more stable and dense.

[0034] Existing fluorination processes mostly employ bulk fluorination, which involves mixing and sintering raw materials containing fluorine (F) with several other raw materials. Since fluorine is distributed both on the surface and inside the electrolyte particles, this falls under the category of bulk doping technology. However, the primary cause of electrolyte hydrolysis or premature degradation of battery cycle stability is functional failure due to chemical and physical changes on the electrolyte particle surface. Therefore, fluorine doped into the electrolyte does not improve electrolyte performance and may even reduce its ionic conductivity. The role of a powder fluidized bed is to suspend solid particles using airflow, creating a fluid-like state. This significantly enhances the contact and reaction between the gas and solid phases, ensuring sufficient contact between each particle and the reactant gas, increasing the reaction contact area, and greatly reducing the reaction temperature. This allows for controllable fluorination rates, achieving fluorination depth control below 150 nanometers on the electrolyte surface. Finally, annealing is used to densify the fluorinated layer.

[0035] The preparation method described above will be further explained and illustrated below with several comparative examples and embodiments: Comparative Example 1 This comparative example provides a halide electrolyte material with the chemical formula Li3YBr3Cl3, and its preparation method is as follows: Under a dry, high-purity argon atmosphere, LiCl and YBr3 were weighed in a molar ratio of 3:1. The weighed raw materials were ground into powder and mixed. The mixture was then sintered at 500°C to obtain the sample.

[0036] Comparative Example 2 This comparative example provides a bulk fluorinated halide electrolyte material with the chemical formula Li3YBr3Cl. 2.98 F 0.02 The preparation method is as follows: Under a dry, high-purity argon atmosphere, LiCl, LiF, and YBr3 were weighed according to their chemical formulas. The weighed raw materials were ground into powder and mixed. The mixture was then sintered at 500°C to obtain the sample.

[0037] Comparative Example 3 This comparative example provides an electrolyte material obtained by surface flotation, the chemical formula of which is Li3YBr3Cl. 2.95 F 0.05 However, the intensity was not controlled and a fluidized bed method was not used for F-oxidation, resulting in uneven particle size and uneven F-element permeation layer on the surface.

[0038] Example 1 This embodiment provides a surface-fluorinated halide electrolyte material with the chemical formula Li. 2.5 GdBr 5.4 F 0.1The fluorinated layer has a depth of 150 nm, and the preparation method is as follows: Under a dry, high-purity argon atmosphere, LiBr and GdBr3 were weighed at a molar ratio of 2.5:1, ground into powder, and mixed. The mixture was then sintered at 400℃ and allowed to cool naturally to obtain the first reactant. The first reactant was then processed using an air jet mill to achieve a particle size distribution of D50 ≤ 3 micrometers to obtain the second reactant. The second reactant was then loaded into a fluidized bed, and a mixture of HF and N2 was introduced. The processing temperature was 50℃, and the reaction time was 20 min. The resulting product was further annealed at 220℃ to obtain the final product.

[0039] Example 2 This embodiment provides a surface-fluorinated halide electrolyte material with the chemical formula Li. 2.8 GdBr 5.72 F 0.08 The fluorinated layer has a depth of 100 nm, and the preparation method is as follows: Under a dry, high-purity argon atmosphere, LiBr and GdBr3 were weighed at a molar ratio of 2.8:1, ground into powder, and mixed. The mixture was then sintered at 450°C and allowed to cool naturally to obtain the first reactant. The first reactant was then processed using an air jet mill to achieve a particle size distribution of D50 ≤ 3 micrometers to obtain the second reactant. The second reactant was then loaded into a fluidized bed, and a mixture of HF and N2 was introduced. The processing temperature was 70°C, and the reaction time was 18 min. The resulting product was further annealed at 250°C to obtain the final product.

[0040] Example 3 This embodiment provides a surface-fluorinated halide electrolyte material with the chemical formula Li. 2.8 GdBr 5.75 F 0.05 The fluorinated layer has a depth of 50 nm, and the preparation method is as follows: Under a dry, high-purity argon atmosphere, LiBr and GdBr3 were weighed at a molar ratio of 2.8:1, ground into powder, and mixed. The mixture was then sintered at 450°C and allowed to cool naturally to obtain the first reactant. The first reactant was then processed using a sand mill to reduce the particle size to D50 ≤ 1 micrometer to obtain the second reactant. The second reactant was then loaded into a fluidized bed, and a mixture of HF and N2 was introduced. The processing temperature was 80°C, and the reaction time was 10 min. The resulting product was further annealed at 300°C to obtain the final product.

[0041] Example 4 This embodiment provides a surface-fluorinated halide electrolyte material with the chemical formula Li3GdBr3Cl. 2.96F 0.04 The fluorinated layer has a depth of 40 nm, and the preparation method is as follows: Under a dry, high-purity argon atmosphere, LiCl and GdBr3 were weighed at a molar ratio of 3:1. The weighed raw materials were ground into powder and mixed. The mixture was then sintered at 500℃ and allowed to cool naturally to obtain the first reactant. The first reactant was then processed by an air jet mill to reduce the particle size to D50 ≤ 1 micrometer to obtain the second reactant. The second reactant was then loaded into a fluidized bed and a mixture of HF and N2 was introduced. The processing temperature was 100℃ and the reaction time was 5 min. The resulting product was further annealed at 280℃ to obtain the final product.

[0042] Example 5 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li3YBr3Cl. 2.98 F 0.02 The fluorinated layer has a depth of 20 nm, and the preparation method is as follows: Under a dry, high-purity argon atmosphere, LiCl and YBr3 were weighed at a molar ratio of 3:1. The weighed raw materials were ground into powder and mixed. The mixture was then sintered at 550℃ and naturally cooled to obtain the first reactant. The first reactant was then processed by an air jet mill to reduce the particle size to D50 ≤ 1 micrometer to obtain the second reactant. The second reactant was then loaded into a fluidized bed and a mixed gas of HF and Ar was introduced. The processing temperature was 65℃ and the reaction time was 3 min. The resulting product was further annealed at 260℃ to obtain the final product.

[0043] Example 6 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li3YBr. 5.99 F 0.01 The fluorinated layer has a depth of 10 nm, and the preparation method is as follows: Under a dry, high-purity argon atmosphere, LiBr and YBr3 were weighed at a molar ratio of 3:1. The weighed raw materials were ground into powder and mixed. The mixture was then sintered at 600℃ and allowed to cool naturally to obtain the first reactant. The first reactant was then processed by an air jet mill to reduce the particle size to D50 ≤ 1 micrometer to obtain the second reactant. The second reactant was then loaded into a fluidized bed and a mixture of HF and Ar was introduced. The processing temperature was 90℃ and the reaction time was 1 min. The resulting product was further annealed at 270℃ to obtain the final product.

[0044] Example 7 This embodiment provides a surface-fluorinated halide electrolyte material with the chemical formula Li3YBr. 5.99 F 0.01The fluorinated layer has a depth of 5 nm and is prepared using the following method: Under a dry, high-purity argon atmosphere, LiCl and YBr3 were weighed in a molar ratio of 3:1. The weighed raw materials were ground into powder and mixed. The mixture was then sintered at 550°C and allowed to cool naturally to obtain the first reactant. The first reactant was then processed by an air jet mill to achieve a particle size distribution of D50 ≤ 5 micrometers to obtain the second reactant. The second reactant was then loaded into a fluidized bed and a mixture of HF and Ar gases was introduced. The processing temperature was 85°C and the reaction time was 1 min. The resulting product was further annealed at 200°C to obtain the final product.

[0045] Example 8 This embodiment provides a surface-fluorinated halide electrolyte material with the chemical formula Li3YBrCl. 4.8 F 0.2 The fluorinated layer has a depth of 150 nm, and the preparation method is as follows: Under a dry, high-purity argon atmosphere, LiCl, LiBr, and YCl3 were weighed in a molar ratio of 2:1:1. The weighed raw materials were ground into powder and mixed. The mixture was then sintered at 550℃ and allowed to cool naturally to obtain the first reactant. The first reactant was then processed by an air jet mill to achieve a particle size distribution of D50 ≤ 5 micrometers to obtain the second reactant. The second reactant was then loaded into a fluidized bed and a mixture of HF and Ar gases was introduced. The processing temperature was 60℃ and the reaction time was 40 min. The resulting product was further annealed at 300℃ to obtain the final product.

[0046] Example 9 This embodiment provides a surface-fluorinated halide electrolyte material with the chemical formula Li. 2.7 GdCl 5.6 F 0.1 The fluorinated layer has a depth of 150 nm, and the preparation method is as follows: Under a dry, high-purity argon atmosphere, LiCl and GdCl3 were weighed at a molar ratio of 2.7:1. The weighed raw materials were ground into powder and mixed. The mixture was then sintered at 400℃ and allowed to cool naturally to obtain the first reactant. The first reactant was then processed by an air jet mill to reduce the particle size to D50 ≤ 5 micrometers to obtain the second reactant. The second reactant was then loaded into a fluidized bed and a mixture of HF and N2 was introduced. The processing temperature was 60℃ and the reaction time was 20 min. The resulting product was further annealed at 220℃ to obtain the final product.

[0047] Example 10 This embodiment provides a surface-fluorinated halide electrolyte material with the chemical formula Li. 2.8 GdCl 5.75 F0.05 The fluorinated layer has a depth of 50 nm, and the preparation method is as follows: Under a dry, high-purity argon atmosphere, LiCl and GdCl3 were weighed at a molar ratio of 2.8:1. The weighed raw materials were ground into powder and mixed. The mixture was then sintered at 400℃ and allowed to cool naturally to obtain the first reactant. The first reactant was then processed by an air jet mill to reduce the particle size to D50 ≤ 1 micrometer to obtain the second reactant. The second reactant was then loaded into a fluidized bed and a mixture of HF and N2 was introduced. The processing temperature was 60℃ and the reaction time was 20 min. The resulting product was further annealed at 220℃ to obtain the final product.

[0048] Example 11 This embodiment provides a surface-fluorinated halide electrolyte material with the chemical formula Li. 2.8 YBr3Cl 2.78 F 0.02 The fluorinated layer has a depth of 20 nm, and the preparation method is as follows: Under a dry, high-purity argon atmosphere, LiCl and YBr3 were weighed at a molar ratio of 2.8:1. The weighed raw materials were ground into powder and mixed. The mixture was then sintered at 400℃ and allowed to cool naturally to obtain the first reactant. The first reactant was then processed by an air jet mill to reduce the particle size to D50 ≤ 1 micrometer to obtain the second reactant. The second reactant was then loaded into a fluidized bed and a mixture of HF and N2 was introduced. The processing temperature was 60℃ and the reaction time was 20 min. The resulting product was further annealed at 220℃ to obtain the final product.

[0049] Example 12 This embodiment provides a surface-fluorinated halide electrolyte material with the chemical formula Li. 2.6 YBr3Cl 2.58 F 0.02 The fluorinated layer has a depth of 20 nm, and the preparation method is as follows: Under a dry, high-purity argon atmosphere, LiCl and YBr3 were weighed at a molar ratio of 2.6:1. The weighed raw materials were ground into powder and mixed. The mixture was then sintered at 400℃ and allowed to cool naturally to obtain the first reactant. The first reactant was then processed by an air jet mill to reduce the particle size to D50 ≤ 1 micrometer to obtain the second reactant. The second reactant was then loaded into a fluidized bed and a mixture of HF and N2 was introduced. The processing temperature was 60℃ and the reaction time was 20 min. The resulting product was further annealed at 220℃ to obtain the final product.

[0050] Example 13 This embodiment provides a surface-fluorinated halide electrolyte material with the chemical formula Li.2.5 YBr3Cl 2.48 F 0.02 The fluorinated layer has a depth of 20 nm, and the preparation method is as follows: Under a dry, high-purity argon atmosphere, LiCl and YBr3 were weighed at a molar ratio of 2.5:1. The weighed raw materials were ground into powder and mixed. The mixture was then sintered at 400℃ and allowed to cool naturally to obtain the first reactant. The first reactant was then processed by an air jet mill to reduce the particle size to D50 ≤ 1 micrometer to obtain the second reactant. The second reactant was then loaded into a fluidized bed and a mixture of HF and N2 was introduced. The processing temperature was 60℃ and the reaction time was 20 min. The resulting product was further annealed at 220℃ to obtain the final product.

[0051] The specific performance tests are as follows: (1) Ionic conductivity test: Under an argon atmosphere, 150 mg of electrolyte powder prepared in the examples and comparative examples was weighed and placed in an insulating test mold sleeve. A pressing pressure of 300 MPa was applied, and the thickness of the electrolyte sheet after pressing was recorded as L (in cm). The cross-sectional area of ​​the electrolyte sheet was recorded as S (in cm²). 2 Subsequently, an AC impedance test was performed using the test mold, and the obtained impedance value was recorded as R, in Ω. The ionic conductivity of the electrolyte material was calculated using the formula σ = L / (R·S), in S / cm. Assembly and testing were conducted under an inert atmosphere, and the tests were performed at room temperature (25℃). (2) Solid-state battery cycle performance test: Under an argon atmosphere, the solid electrolyte, positive electrode active material, and conductive carbon black prepared in the examples and comparative examples were weighed in a ratio of 20:75:5 and uniformly mixed to prepare a composite positive electrode material. 70 mg of solid electrolyte was added to an insulating test sleeve with a diameter of 10 mm, and a pressure of 300 MPa was applied and held for 120 seconds to form the solid electrolyte layer. 20 mg of the obtained composite positive electrode material was poured into one side of the pre-pressed electrolyte layer, and a pressure of 360 MPa was applied and held for 120 seconds to form the composite positive electrode material. A lithium indium alloy sheet was inserted into the other side of the electrolyte layer, and a pressure of 80 MPa was applied to form the composite positive electrode layer. The composite positive electrode layer, solid electrolyte layer, lithium indium alloy sheet, and stainless steel current collectors on both sides constituted a test all-solid-state battery.

[0052] The assembled all-solid-state battery pack was placed in a 25°C constant temperature chamber for cycle performance testing. The test conditions were: first-cycle charge-discharge performance and 200-cycle charge-discharge performance testing of the solid-state battery using a current density of 0.1C.

[0053] The results of Examples 1-13 and Comparative Examples 1-3 are shown in Table 1. Table 1. Test results of Examples 1-13 and Comparative Examples 1-3 Table 1 shows that, comparing Examples 1-10 and Comparative Examples 1-3, the all-solid-state battery prepared using the surface-fluorinated electrolyte of the present invention exhibits a capacity retention rate >90% after 200 cycles, and a charge / discharge voltage ≥4.4V, significantly higher than that of unfluorinated, bulk-fluorinated, and non-fluidized-bed fluorinated batteries (Comparative Examples 1-3). Examples 3-6 compared to Examples 1-2 demonstrate that when the electrolyte particle size D50 ≤ 1µm, the prepared battery has a higher discharge specific capacity. A comparison of Examples 5, 11, 12 and Example 13 shows that the battery prepared after matching the fluorinated electrolyte with the high-voltage active material (≥4.4V) has a wider operating voltage range and a higher first-cycle discharge specific capacity.

[0054] In summary, the halide solid electrolyte obtained by this invention has good cathode matching effect, high ionic conductivity, high oxidation stability potential, good matching with cathode active material, and good first-efficiency and cycle stability of the prepared solid battery.

[0055] Accordingly, a third aspect of the present invention provides a lithium-ion battery, comprising: a positive electrode layer, a negative electrode layer, and an electrolyte layer located between the positive electrode layer and the negative electrode layer, wherein the electrolyte layer comprises the above-described halide solid electrolyte material or a halide solid electrolyte material prepared by the above-described halide solid electrolyte material preparation method.

[0056] Furthermore, the operating voltage of the active material in the positive electrode layer is ≥4.4V.

[0057] Furthermore, the active material of the positive electrode layer is any one of NMC, LNMO, and lithium-rich manganese-based morphological oxides.

[0058] Lithium-ion batteries not only possess the prerequisite of high energy density due to the use of high-voltage cathodes, but also benefit from the excellent oxidation stability and good cathode / electrolyte interface compatibility of the electrolyte layer material. This effectively suppresses interfacial side reactions and maintains stable interfacial ion transport during high-voltage operation, ultimately enabling the battery to exhibit excellent cycle life and capacity retention at high energy density.

[0059] The embodiments of this invention aim to protect a halide solid electrolyte material and its preparation method, as well as a lithium-ion battery, and have the following effects: 1. By limiting the distribution of fluorine to a specific depth on the surface of the powder particles, the fluoride layer effectively passivates the electrolyte surface and improves its oxidation potential, thereby avoiding interface deterioration caused by electrolyte oxidation during charging and discharging. At the same time, the ultra-fine and uniform powder particle size ensures good matching and close contact with the positive electrode active material particles, effectively stabilizing the interfacial current distribution. Together, these factors enable the battery to maintain an extremely high capacity retention rate during long-term cycling. 2. By adopting fluidized bed fluorination, the fluorination reaction gas can be made into uniform and sufficient contact with the surface of electrolyte particles under mild conditions, realizing the controllable doping of fluorine in the shallow surface layer of particles; avoiding the destruction of the conductive main structure by the bulk fluorine, thus using fluorine to improve the interfacial stability while maximizing the preservation of the excellent high ionic conductivity of the material, achieving a unity of high ionic conductivity and high interfacial stability. 3. Particle size control and surface fluorination ensure a uniform ion / electron conduction network within the positive electrode layer and compatibility with the high-voltage positive electrode. This not only directly improves the battery's first-cycle discharge capacity but also fundamentally suppresses the degradation of the positive electrode interface under high voltage, enabling all-solid-state batteries using this electrolyte to exhibit both high energy density and ultra-long cycle life.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A halide solid electrolyte material, characterized in that, The general chemical formula of the electrolyte material is Li. a MX b F c M is Y or Gd, X is at least one of Cl and Br, 2.5≤a≤3, 5.4≤b≤5.99, 0.01≤c≤0.1; The electrolyte material is in the form of powder particles, and the particle size D of the powder particles is... 50 ≤5μm; F element is distributed on the surface of powder particles at a depth of ≥5nm and ≤150nm.

2. The halide solid electrolyte material according to claim 1, characterized in that, The room temperature ionic conductivity of the electrolyte material is ≥3 mS / cm.

3. The halide solid electrolyte material according to claim 1, characterized in that, The electrolyte powder particle size D 50 ≤1μm.

4. A method for preparing a halide solid electrolyte material, characterized in that, The preparation of the halide solid electrolyte material as described in any one of claims 1-3 includes the following steps: S1: Lithium halide and metal M halide are mixed and ground according to chemical formula ratio, and sintered at a first preset temperature in an environment isolated from water and oxygen to obtain the first reactant. S2: The first reactant is crushed to obtain a second reactant with a preset powder particle size; S3: After the second reactant is subjected to fluorination treatment by powder fluidization, it is then subjected to high-temperature annealing at a second preset temperature to obtain a powder granular electrolyte material.

5. The method for preparing halide solid electrolyte materials according to claim 4, characterized in that, The fluorination treatment of the second reactant by powder fluidization includes: The second reactant is loaded into a fluidized bed protected by an inert gas. A mixed gas containing HF is introduced while the powder is in a fluidized state. After being treated at a third preset temperature for a first preset time, a high-temperature annealing treatment is performed.

6. The method for preparing halide solid electrolyte materials according to claim 5, characterized in that, The mixed gas includes: a mixture of HF and N2 or a mixture of HF and Ar; The numerical range of the third preset temperature is 50℃~100℃; The first preset duration is 1 min to 20 min.

7. The method for preparing halide solid electrolyte materials according to any one of claims 4-6, characterized in that, The water and oxygen isolation environment is a vacuum, argon, or nitrogen condition. The first preset temperature is 400℃~600℃; The second preset temperature is 200℃~300℃; The particle size D of the preset powder particle size 50 ≤5μm.

8. A lithium-ion battery, characterized in that, include: A positive electrode layer, a negative electrode layer, and an electrolyte layer located between the positive electrode layer and the negative electrode layer, wherein the electrolyte layer comprises a halide solid electrolyte material as described in any one of claims 1-3 or a halide solid electrolyte material prepared by any one of the halide solid electrolyte material preparation methods described in claims 4-7.

9. The lithium-ion battery according to claim 8, characterized in that, The active material of the positive electrode layer operates at a voltage ≥4.4V.

10. The lithium-ion battery according to claim 8, characterized in that, The active material of the positive electrode layer is any one of NMC, LNMO, and lithium-rich manganese-based morphological oxides.

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