Preparation method of Al and Cl doped Li7Zn0. 5SiS6 composite carbon nanotube coated and modified ultra-high nickel positive electrode

Abstract

The invention belongs to the technical field of lithium ion battery materials, and discloses a coating material and a preparation method thereof, a coated modified positive electrode material and a preparation method thereof, and a battery. The preparation method comprises the following steps: mixing Li2S, ZnS and SiS2 with a proper amount of Al2S3 and LiCl in proportion, and carrying out high-temperature treatment in an inert atmosphere through a two-step solid phase method to prepare Al and Cl doped Li7Zn0. 5SiS6 powder; and then compounding the composite material with CNT in an argon atmosphere, and carrying out low-temperature densification treatment to obtain the coating material. And mixing the coating material with a base material, and sintering in an inert atmosphere to obtain the surface-coated modified positive electrode material. The crystal lattice stability and interface chemical inertness of sulfide are regulated and controlled by doping Al and Cl, and meanwhile, CNT is introduced to construct an electron-ion double-conduction network, so that the interface impedance is remarkably reduced, side reaction is inhibited, and the cycling stability of the positive electrode is improved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery cathode materials technology, specifically to a sulfide solid electrolyte Li7Zn doped with Al and Cl. 0.5 A method for coating and modifying ultra-high nickel cathode materials with SiS6 composite carbon nanotubes (CNTs). Background Technology

[0002] Ultra-high nickel layered oxide cathodes (such as LiNi) x Co y Mn z O2 (x≥0.90, hereinafter referred to as "ultra-high nickel cathode") has become a key development direction for power and energy storage batteries due to its high specific capacity and high energy density. However, this type of material is prone to electrolyte oxidation, by-product deposition, and microcrack-induced structural degradation during high-voltage and high-temperature cycling, which manifests as a rapid increase in interfacial impedance, a decrease in capacity retention, and a shortened cycle life.

[0003] To improve its interfacial stability, researchers proposed constructing an ion-conducting layer on the cathode surface using solid electrolyte materials. Sulfide-type solid electrolytes, due to their high room temperature Li... + Electrical conductivity and good interfacial wettability make Li7Zn an important candidate for coating modification. 0.5 SiS6 exhibits excellent ion conductivity and thermal stability, enabling the formation of a lithium-rich "ion channel coating layer" on the cathode surface, effectively suppressing side reactions and reducing interfacial impedance.

[0004] However, a single Li7Zn 0.5 SiS6 may still exhibit structural distortion and insufficient electronic conduction during long-term electrochemical operation. This invention improves its lattice stability and interfacial chemical inertness by introducing Al and Cl co-doping, and simultaneously constructs an electron / ion dual-conductivity composite coating layer with excellent CNT composite conductivity, which significantly enhances the cycle performance of the ultra-high nickel cathode. Summary of the Invention

[0005] The primary objective of this invention is to provide a coating material for lithium-ion battery cathode materials and a method for preparing the same.

[0006] The second objective of this invention is to provide a cathode material and a method for preparing the same.

[0007] A third objective of this invention is to provide a battery.

[0008] To achieve the above objectives, the present invention provides the following specific technical solutions.

[0009] In a first aspect, the present invention provides a method for preparing a coating material, comprising the following steps: Step S1: Lithium sulfide (Li2S), zinc sulfide (ZnS), silicon powder (Si), and sulfur powder (S) are mixed in a certain proportion, and a certain amount of aluminum source and chlorine source are introduced. After ball milling, the mixture is heat-treated in an inert atmosphere or a vacuum-sealed environment to obtain Al and Cl-doped Li7Zn. 0.5 SiS6 powder; Step S2: The powder obtained in step S1 is mixed with carbon nanotubes (CNTs) in a certain proportion and then vacuum annealed to obtain Al and Cl-doped Li7Zn. 0.5 SiS6 / CNT composite coating material.

[0010] In a further preferred embodiment, the molar ratio of lithium sulfide, zinc sulfide, silicon powder, and sulfur powder is 7:0.5:1:6.

[0011] In a further preferred embodiment, the inert atmosphere is one of high-purity argon, high-purity nitrogen, or a vacuum environment, preferably with a vacuum degree of less than 10⁻. 4 A vacuum environment of mbar.

[0012] In a further preferred embodiment, the heat treatment temperature is 500–1000℃, preferably 700℃; the heat treatment time is 6–30 h, preferably 24 h; and the heat treatment is performed 1–4 times, preferably 2 times.

[0013] In a further preferred embodiment, the Al doping source is selected from one or more of the following: AlCl3, LiAlS2, Al2S3, Al2O3, Al(OH)3, Al(NO3)3, Al2(SO4)3, Al(OiPr)3, Al(acac)3 or their lithium complexes; the Cl doping source is selected from one or more of the following: LiCl, NaCl, KCl, MgCl2, CaCl2, AlCl3, NH4Cl or chlorine-containing organic salts (such as acetyl chloride, isopropyl trichloride); the above doping sources can be used alone or in combination to achieve the synergistic introduction of Al and Cl elements.

[0014] In a further preferred embodiment, the Al:Si molar ratio is controlled at 0.005~0.1:1, preferably 0.03:1; the Cl:S molar ratio is controlled at 0.015~0.10:1, preferably 0.06:1.

[0015] In a further preferred embodiment, the mass ratio of powder to CNT in step S2 is 1:0.05~0.3, preferably 1:0.1, and the powder is annealed in a vacuum or inert atmosphere at 250–400°C to form a stable interfacial composite structure.

[0016] Based on the same inventive concept, the present invention provides Al and Cl doped Li7Zn prepared by the above preparation method. 0.5 SiS6 / CNT composite coating material.

[0017] Based on the same inventive concept, the present invention provides a coating material prepared by the above-described preparation method.

[0018] Secondly, the present invention provides a coated modified cathode material, including a coating layer, wherein the material of the coating layer is the aforementioned coating material.

[0019] In a further preferred embodiment, the coated and modified cathode material comprises a matrix, with the coating layer located on at least a portion of the surface of the matrix; the matrix is ​​a ternary cathode material. More preferably, the general chemical formula of the matrix is ​​LiNi. x Co y Mn z O2, where 0.90 ≤ x ≤ 0.97, 0 ≤ y ≤ 0.07, 0.01 ≤ z ≤ 0.08, and x + y + z = 1.

[0020] The present invention also provides a method for preparing the above-mentioned positive electrode material, comprising: mixing a matrix with a coating material and sintering it under an inert atmosphere to form a dense composite coating layer.

[0021] In a further preferred embodiment, the inert atmosphere is high-purity argon or high-purity nitrogen.

[0022] In a further preferred embodiment, the mass ratio of the coating material to the substrate is 0.1:3~100, preferably 0.5–1.0 wt%; the sintering temperature is 250–600℃, preferably 400℃; and the sintering time is 2–10 h.

[0023] Furthermore, the present invention provides a battery comprising the aforementioned coated and modified cathode material.

[0024] The above-described one or more technical solutions of the present invention can achieve at least one of the following beneficial effects: The coating material provided by this invention can significantly improve the ionic conductivity of the cathode material, thereby increasing the energy density, cycle stability, and high-rate discharge performance of the battery. Attached Figure Description

[0025] Figure 1 In step S2 of Example 1, Al, Cl-Li7Zn 0.5 SEM image of SiS6 / CNT composite powder.

[0026] Figure 2 In step S2 of Example 1, Al, Cl-Li7Zn0.5 EDS image of S, Al and Cl elements in SiS6 and CNT composite powder.

[0027] Figure 3 In step S2 of Example 1, Al, Cl-Li7Zn 0.5 Molar percentage analysis of each element in SiS6 and CNT composite powder. Detailed Implementation

[0028] In a first aspect, some embodiments of the present invention provide an Al, Cl co-doped Li7Zn 0.5 The preparation method of SiS6 composite CNT coating material includes the following steps: Step S1: Lithium sulfide (Li2S), zinc sulfide (ZnS), silicon powder (Si), and sulfur powder (S) are mixed in a certain proportion, and a certain amount of aluminum source and chlorine source are introduced. After ball milling, the mixture is heat-treated in an inert atmosphere or a vacuum-sealed environment to obtain Al and Cl-doped Li7Zn. 0.5 SiS6 powder; Step S2: The powder obtained in step S1 is mixed with carbon nanotubes (CNTs) in a certain proportion and then vacuum annealed to obtain Al and Cl-doped Li7Zn. 0.5 SiS6 / CNT composite coating material.

[0029] In some specific embodiments, the molar ratio of lithium sulfide, zinc sulfide, silicon powder, and sulfur powder is 7:0.5:1:6.

[0030] In some specific embodiments, the inert atmosphere is one of high-purity argon, high-purity nitrogen, or a vacuum environment, preferably with a vacuum degree of less than 10⁻. 4 A vacuum environment of mbar.

[0031] In some specific embodiments, the heat treatment temperature is 500–1000℃, preferably 700℃; the heat treatment time is 6–30 h, preferably 24 h; and the heat treatment is performed 1–4 times, preferably 2 times.

[0032] In some specific embodiments, the Al doping source is selected from one or more of the following: AlCl3, LiAlS2, Al2S3, Al2O3, Al(OH)3, Al(NO3)3, Al2(SO4)3, Al(OiPr)3, Al(acac)3 or their lithium complexes; the Cl doping source is selected from one or more of the following: LiCl, NaCl, KCl, MgCl2, CaCl2, AlCl3, NH4Cl or chlorine-containing organic salts (such as acetyl chloride, isopropyl trichloride); the above doping sources can be used alone or in combination to achieve the synergistic introduction of Al and Cl elements.

[0033] In some specific embodiments, the Al:Si molar ratio is controlled at 0.005~0.1:1, preferably 0.03:1; the Cl:S molar ratio is controlled at 0.015~0.10:1, preferably 0.06:1.

[0034] In some specific embodiments, the mass ratio of powder to CNT in step S2 is 1:0.05~0.3, preferably 1:0.1, and the powder is annealed in a vacuum or inert atmosphere at 250–400°C to form a stable interfacial composite structure.

[0035] Some embodiments of the present invention provide coating materials prepared by the above-described preparation method.

[0036] Analysis suggests that sulfide-type solid electrolytes, due to their high room temperature Li... + Electrical conductivity and good interfacial wettability make Li7Zn an important candidate for coating modification. 0.5 SiS6 exhibits excellent ion conductivity and thermal stability, enabling the formation of a lithium-rich "ion channel coating layer" on the cathode surface, effectively suppressing side reactions and reducing interfacial impedance. Furthermore, the introduction of Al and Cl co-doping further improves its lattice stability and interfacial chemical inertness. Simultaneously, the composite of highly conductive CNTs constructs an electron / ion dual-conductivity composite coating layer, allowing this modified layer to possess both excellent ion migration channels and an electron buffer network under high voltage and high temperature conditions, thereby significantly enhancing the cycle and rate performance of the ultra-high nickel cathode.

[0037] Secondly, some embodiments of the present invention provide a coated modified cathode material, including a coating layer, wherein the material of the coating layer is the aforementioned coating material.

[0038] The coated and modified cathode material includes a matrix, and the coating layer is located on at least a portion of the surface of the matrix; the matrix is ​​a ternary cathode material.

[0039] In a further preferred embodiment, the coated and modified cathode material comprises a matrix, with the coating layer located on at least a portion of the surface of the matrix; the matrix is ​​a ternary cathode material. More preferably, the general chemical formula of the matrix is ​​LiNi. x Co y Mn z O2, where 0.90 ≤ x ≤ 0.97, 0 ≤ y ≤ 0.07, 0.01 ≤ z ≤ 0.08, and x + y + z = 1.

[0040] Some embodiments of the present invention also provide a method for preparing the above-mentioned cathode material, including: mixing a matrix with a coating material and sintering it under an inert atmosphere to form a dense composite coating layer.

[0041] In some specific embodiments, the inert atmosphere is high-purity argon or high-purity nitrogen.

[0042] In some specific embodiments, the mass ratio of the coating material to the substrate is 0.1:3~100, preferably 0.5–1.0 wt%; the sintering temperature is 250–600℃, preferably 400℃; and the sintering time is 2–10 h.

[0043] Furthermore, the present invention provides a battery comprising the aforementioned coated and modified cathode material.

[0044] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0045] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0046] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0047] Example 1 Step S1: Weigh out the following high-purity reagents: 532 mg Li₂S (99.98%), 161 mg ZnS (99.99%), 93 mg Si (325 mesh, 99.5%), and 637 mg S (99.999%). To achieve Al and Cl co-doping, add an additional 13.3 mg AlCl₃ (Al:Si molar ratio ≈ 0.03) and 50.5 mg LiCl (Cl:S molar ratio ≈ 0.06). Grind and mix the above reagents thoroughly in an agate mortar for 15 min to ensure high homogeneity of the components. Place the mixture into a carbon-coated quartz tube and evacuate it (vacuum degree <10⁻). 4 After sintering at 700 °C for 24 h, the tube was sealed. The product was then removed, cooled, and ground again until homogeneous. The vacuum sealing process was repeated, followed by a second sintering at 700 °C for 24 h (heating and cooling rates controlled at 5 °C / min). High-purity Al,Cl-Li7Zn was obtained after both sintering processes. 0.5 SiS6 powder.

[0048] Step S2, the Al, Cl-Li7Zn obtained in step S1 0.5SiS6 powder was mixed with CNT at a mass ratio of 10:1. The mixture contained 150 mg of CNT and Al, Cl-Li7Zn. 0.5 Approximately 1.50 g of SiS6 was prepared. CNTs were first dispersed in 50 mL of anhydrous ethanol and sonicated for 1 h to obtain a stable suspension; then Al, Cl-Li7Zn was slowly added. 0.5 SiS6 powder was sonicated for 30 min and then further stirred magnetically for 2 h to promote sufficient contact and interfacial adsorption between the powder and CNTs. The resulting slurry was dried under vacuum at 80 °C for 12 h to remove the solvent, and then lightly ground in a mortar to eliminate agglomeration. The composite powder was annealed at 300 °C for 2 h in an Ar atmosphere at a heating rate of 3 °C / min to obtain Al,Cl-Li7Zn. 0.5 A complex of SiS6 and CNT.

[0049] Figure 1 Here is a SEM image of the complex. Figure 2 EDS image of Al and Cl in the complex. From Figure 1 The presence of distinct CNT tubular structures on the outer layer of the composite indicates that CNTs were successfully incorporated into the composite. Figure 2 It can be seen that the distribution trends of Al and Cl elements are similar to those of S element, but the content of Al and Cl elements is low and dispersed, indicating that Al and Cl elements mainly exist in Li7Zn as dopants. 0.5 In SiS6. Figure 3 The Al, Cl-Li7Zn prepared in this embodiment 0.5 The elemental molar content distribution diagram of SiS6 shows that Li7Zn 0.5 The molar ratio of SiS6 to AlCl3 basically conforms to the designed molar ratio, that is, Al:Si molar ratio≈0.03 and Cl:S molar ratio≈0.06.

[0050] Step S3: The composite obtained in step S2 is combined with the nickel-cobalt-manganese ternary cathode material LiNi. 0.93 Co 0.04 Mn 0.03 O2 was mixed at a mass ratio of 1:99 and then vacuum dried at 120°C for 12 hours. Subsequently, it was sintered at 400°C for 6 hours under an argon atmosphere to obtain the coated and modified cathode material.

[0051] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the Al and Cl co-doping process in step S1 is omitted. Specifically: Step S1: Weigh the following high-purity reagents: 532 mg Li₂S (99.98%), 161 mg ZnS (99.99%), 93 mg Si (325 mesh, 99.5%), and 637 mg S (99.999%). Grind and mix the above reagents thoroughly in an agate mortar for 15 min to ensure high homogeneity of the components. Place the mixture into a carbon-coated quartz tube and evacuate it (vacuum degree <10⁻). 4 After sintering at 700 °C for 24 h, the tube was sealed. The product was then removed and cooled, the tube opened, and ground again until homogeneous. The vacuum sealing process was repeated, followed by a second sintering at 700 °C for 24 h (heating and cooling rates controlled at 5 °C / min). High-purity Li7Zn was obtained after both sintering processes. 0.5 SiS6 powder.

[0052] Step S2, take the Li7Zn obtained in step S1 0.5 SiS6 powder was mixed with CNT at a mass ratio of 10:1. The mixture contained 150 mg of CNT and 150 mg of Li7Zn. 0.5 Approximately 1.50 g of SiS6 was prepared. CNTs were first dispersed in 50 mL of anhydrous ethanol and sonicated for 1 h to obtain a stable suspension; then Li7Zn was slowly added. 0.5 SiS6 powder was sonicated for 30 min and then further stirred magnetically for 2 h to promote sufficient contact and interfacial adsorption between the powder and CNTs. The resulting slurry was dried under vacuum at 80 °C for 12 h to remove the solvent, and then lightly ground in a mortar to eliminate agglomeration. The composite powder was annealed at 300 °C for 2 h in an Ar atmosphere at a heating rate of 3 °C / min to obtain Li7Zn. 0.5 A complex of SiS6 and CNT.

[0053] Step S3: The composite obtained in step S2 is combined with the nickel-cobalt-manganese ternary cathode material LiNi. 0.93 Co 0.04 Mn 0.03 O2 was mixed at a mass ratio of 1:99 and then vacuum dried at 120°C for 12 hours. Subsequently, it was sintered at 400°C for 6 hours under an argon atmosphere to obtain the coated and modified cathode material.

[0054] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the Al and Cl co-doping process in step S1 is absent, and the CNT recombination process in step S2 of Example 1 is absent.

[0055] Step S1 is the same as step S1 in Comparative Example 1.

[0056] Step S2, the Li7Zn obtained in step S1 0.5SiS6 and nickel-cobalt-manganese ternary cathode material LiNi 0.93 Co 0.04 Mn 0.03 O2 was mixed at a mass ratio of 1:99 and then vacuum dried at 120°C for 12 hours. Subsequently, it was sintered at 400°C for 6 hours under an argon atmosphere to obtain the coated and modified cathode material.

[0057] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the cathode material is not modified by coating.

[0058] Example 2 Step S1: Weigh out the following high-purity reagents: 532 mg Li₂S (99.98%), 161 mg ZnS (99.99%), 93 mg Si (325 mesh, 99.5%), and 637 mg S (99.999%). To achieve Al and Cl co-doping, add an additional 2.05 mg AlCl₃ (Al:Si molar ratio ≈ 0.005) and 12.625 mg LiCl (Cl:S molar ratio ≈ 0.015). Grind and mix the above reagents thoroughly in an agate mortar for 15 min to ensure high homogeneity of the components. Place the mixture into a carbon-coated quartz tube and evacuate it (vacuum degree <10⁻). 4 After sintering at 500 °C for 6 h, the tube was sealed. The product was then removed and cooled, the tube opened, and ground again until homogeneous. The vacuum sealing process was repeated, followed by a second sintering at 500 °C for 6 h (heating and cooling rates controlled at 5 °C / min). High-purity Al,Cl-Li7Zn was obtained after both sintering processes. 0.5 SiS6 powder.

[0059] Step S2, the Al, Cl-Li7Zn obtained in step S1 0.5 SiS6 powder was mixed with CNT at a mass ratio of 10:0.5. The mixture contained 75 mg of CNT and Al, Cl-Li7Zn. 0.5 Approximately 1.50 g of SiS6 was prepared. CNTs were first dispersed in 50 mL of anhydrous ethanol and sonicated for 1 h to obtain a stable suspension; then Al, Cl-Li7Zn was slowly added. 0.5 SiS6 powder was sonicated for 30 min and then further stirred magnetically for 2 h to promote sufficient contact and interfacial adsorption between the powder and CNTs. The resulting slurry was dried under vacuum at 80 °C for 12 h to remove the solvent, and then lightly ground in a mortar to eliminate agglomeration. The composite powder was annealed at 250 °C for 2 h in an Ar atmosphere at a heating rate of 3 °C / min to obtain Al,Cl-Li7Zn. 0.5 A complex of SiS6 and CNT.

[0060] Step S3: The composite obtained in step S2 is combined with the nickel-cobalt-manganese ternary cathode material LiNi. 0.73 Co 0.14 Mn 0.13 O2 was mixed at a mass ratio of 0.1:100 and then vacuum dried at 120°C for 12 hours. Subsequently, it was sintered at 250°C for 2 hours under an argon atmosphere to obtain the coated and modified cathode material.

[0061] Example 3 Step S1: Weigh out the following high-purity reagents: 532 mg Li₂S (99.98%), 161 mg ZnS (99.99%), 93 mg Si (325 mesh, 99.5%), and 637 mg S (99.999%). To achieve Al and Cl co-doping, add an additional 44.3 mg AlCl₃ (Al:Si molar ratio ≈ 0.03) and 84.2 mg LiCl (Cl:S molar ratio ≈ 0.1). Grind and mix the above reagents thoroughly in an agate mortar for 15 min to ensure high homogeneity of the components. Place the mixture into a carbon-coated quartz tube and evacuate it (vacuum degree <10⁻). 4 After sintering at 1000 °C for 30 h, the tube was sealed. The product was then removed, cooled, and ground again until homogeneous. The vacuum sealing process was repeated, followed by a second sintering at 1000 °C for 30 h (heating and cooling rates controlled at 5 °C / min). High-purity Al,Cl-Li7Zn was obtained after both sintering processes. 0.5 SiS6 powder.

[0062] Step S2, the Al, Cl-Li7Zn obtained in step S1 0.5 SiS6 powder was mixed with CNT at a mass ratio of 10:3. The mixture contained 150 mg of CNT and Al, Cl-Li7Zn. 0.5 Approximately 1.50 g of SiS6 was prepared. CNTs were first dispersed in 50 mL of anhydrous ethanol and sonicated for 1 h to obtain a stable suspension; then Al, Cl-Li7Zn was slowly added. 0.5 SiS6 powder was sonicated for 30 min and then further stirred magnetically for 2 h to promote sufficient contact and interfacial adsorption between the powder and CNTs. The resulting slurry was dried under vacuum at 80 °C for 12 h to remove the solvent, and then lightly ground in a mortar to eliminate agglomeration. The composite powder was annealed at 400 °C for 2 h in an Ar atmosphere at a heating rate of 3 °C / min to obtain Al,Cl-Li7Zn. 0.5 A complex of SiS6 and CNT.

[0063] Step S3: The composite obtained in step S2 is combined with the nickel-cobalt-manganese ternary cathode material LiNi. 0.83Co 0.04 Mn 0.13 O2 was mixed at a mass ratio of 3:100 and then vacuum dried at 120°C for 12 hours. Subsequently, it was sintered at 600°C for 10 hours under an argon atmosphere to obtain the coated and modified cathode material.

[0064] Example 4 Step S1: Weigh out the following high-purity reagents: 532 mg Li₂S (99.98%), 161 mg ZnS (99.99%), 93 mg Si (325 mesh, 99.5%), and 637 mg S (99.999%). To achieve Al and Cl co-doping, add an additional 20.1 mg AlCl₃ (Al:Si molar ratio ≈ 0.0475) and 35.8 mg LiCl (Cl:S molar ratio ≈ 0.0425). Grind and mix the above reagents thoroughly in an agate mortar for 15 min to ensure high homogeneity of the components. Place the mixture into a carbon-coated quartz tube and evacuate it (vacuum degree <10⁻). 4 After sintering at 750 °C for 18 h, the tube was sealed. The product was then removed, cooled, and ground again until homogeneous. The vacuum sealing process was repeated, followed by a second sintering at 750 °C for 18 h (heating and cooling rates controlled at 5 °C / min). High-purity Al,Cl-Li7Zn was obtained after both sintering processes. 0.5 SiS6 powder.

[0065] Step S2, the Al, Cl-Li7Zn obtained in step S1 0.5 SiS6 powder was mixed with CNT at a mass ratio of 12.5:1. The mixture contained 168.8 mg of CNT and Al, Cl-Li7Zn. 0.5 Approximately 1.50 g of SiS6 was prepared. CNTs were first dispersed in 50 mL of anhydrous ethanol and sonicated for 1 h to obtain a stable suspension; then Al, Cl-Li7Zn was slowly added. 0.5 SiS6 powder was sonicated for 30 min and then further stirred magnetically for 2 h to promote sufficient contact and interfacial adsorption between the powder and CNTs. The resulting slurry was dried under vacuum at 80 °C for 12 h to remove the solvent, and then lightly ground in a mortar to eliminate agglomeration. The composite powder was annealed in an Ar atmosphere at 325 °C for 2 h at a heating rate of 3 °C / min to obtain Al,Cl-Li7Zn. 0.5 A complex of SiS6 and CNT.

[0066] Step S3: The composite obtained in step S2 is combined with the nickel-cobalt-manganese ternary cathode material LiNi. 0.9 Co 0.045 Mn 0.05O2 was mixed at a mass ratio of 1.45:100 and then vacuum dried at 120°C for 12 hours. Subsequently, it was sintered at 325°C for 5 hours under an argon atmosphere to obtain the coated and modified cathode material.

[0067] The coated and modified cathode materials obtained in Examples 1-4 and Comparative Examples 1-3, as well as LiNi, were respectively used. 0.93 Co 0.04 Mn 0.03 O2 is assembled into batteries: A uniform positive electrode slurry was prepared by mixing the positive electrode material, Super-P, KS-6, and polyvinylidene fluoride (PVDF) in an N-methyl-2-pyrrolidone (NMP) at a mass ratio of 90:5:2:3. The prepared positive electrode slurry was uniformly coated onto aluminum foil using a high-speed coater to ensure even coating. It was then dried under vacuum at 120°C for 12 hours to ensure complete evaporation of the NMP and obtain a dry positive electrode material layer, thus obtaining the positive electrode sheet. The positive electrode sheet was then cut into circular pieces (12-15 mm in diameter) suitable for button batteries.

[0068] The negative electrode is a lithium metal sheet, the separator is a Celgard-2400 separator, the electrolyte is a 1M LiPF6 solution dissolved in EC+DMC+EMC (volume ratio 1:1:1), and the positive electrode current collector is aluminum foil.

[0069] Place the negative electrode shell on the assembly table; place the lithium metal negative electrode sheet into the negative electrode shell; place the Celgard-2400 separator on the negative electrode sheet, ensuring a tight cover; add an appropriate amount of electrolyte to the separator, ensuring the separator and negative electrode sheet are fully wetted; place the dried positive electrode sheet on top of the separator; add a small amount of electrolyte to the positive electrode sheet; place the metal gasket and spring sheet in sequence to ensure tight internal contact; place the positive electrode shell on top; use a button cell battery packaging machine to seal the battery, ensuring it is sealed and preventing electrolyte leakage.

[0070] Battery testing: The test temperature is 25℃, the operating voltage range is 3.0-4.3 V, and the battery is cycled 2 times at 0.1C, and then 100 times at 0.5C, 1C, and 2C.

[0071] The test results are shown in Table 1.

[0072] cathode materials 0.1C initial discharge specific capacity (mAh / g) 0.5C initial discharge specific capacity (mAh / g) 1C initial discharge specific capacity (mAh / g) 2C first discharge specific capacity (mAh / g) Capacity retention (%) after 100 cycles at 0.5C Capacity retention rate (%) after 100 cycles at 1C Capacity retention rate (%) after 100 cycles of 2C Example 1 214 211 206 200 95.3 91.2 86.1 Comparative Example 1 208 201 199 198 93.2 89.7 84.8 Comparative Example 2 207 200 198 196 92.8 89.3 84.0 Comparative Example 3 206 199 197 195 83.1 78.3 74.8 Example 2 183 178 174 169 97.8 95.0 90.5 Example 3 190 188 180 179 96.6 93.4 88.3 Example 4 206 200 197 194 95.7 91.6 86.9 As can be seen from the data in Table 1, Example 1 uses Al, Cl-Li7Zn 0.5 SiS6 / CNT composite coating LiNi 0.93 Co 0.04 Mn 0.03 The battery assembled with O2 cathode material exhibits high cycle stability at 0.5C, 1C, and 2C. Comparative Example 1 uses Li7Zn...0.5 SiS6 / CNT composite coating LiNi 0.93 Co 0.04 Mn 0.03 The battery assembled with O2 cathode material exhibited significantly lower cycle stability at 0.5C, 1C, and 2C compared to Example 1. This may be because the co-doping of Al and Cl significantly improves the performance of Li7Zn. 0.5 The lattice stability and interfacial chemical inertness of SiS6 enhance the ion transport capability of the coating layer. Comparative Example 2 uses Li7Zn... 0.5 SiS6 coated LiNi 0.93 Co 0.04 Mn 0.03 The battery assembled with O2 cathode material exhibited lower cycle stability at 0.5C, 1C, and 2C compared to Comparative Example 1, and significantly lower stability compared to Example 1. This may be due to the lack of CNTs in the coating layer, which greatly limits the construction of the electron-ion dual-conductivity network in the composite, increases interfacial resistance, and is detrimental to improving electrochemical performance. In Comparative Example 3, LiNi... 0.93 Co 0.04 Mn 0.03 The battery assembled with O2 cathode material exhibited relatively poor cycle stability at 0.5C, 1C, and 2C, indicating that the electrochemical performance of the unmodified cathode material is easily affected by microcracks and electrolyte erosion. Examples 2, 3, and 4 adjusted the doping amounts of Al and Cl, as well as the CNT composite amount, compared to Example 1. Both excessively low and high doping and composite amounts negatively impacted the battery's cycle stability. The adjusted process parameters in Examples 2, 3, and 4 resulted in some fluctuation in the cycle stability of the corresponding cathode materials at 0.5C, 1C, and 2C, but all showed good cycle stability.

[0073] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for producing a coated material, characterized by, Includes the following steps: Step S1: Lithium sulfide, zinc sulfide, silicon powder and sulfur powder are mixed in proportion, and a certain amount of aluminum source and chlorine source are introduced. After ball milling and mixing, the mixture is heat-treated in an inert atmosphere or vacuum sealed environment to obtain the corresponding powder. Step S2: The powder obtained in step S1 is mixed with carbon nanotubes (CNTs) in proportion and annealed in an inert atmosphere to obtain the coating material.

2. The method for preparing the coating material as described in claim 1, characterized in that, The molar ratio of lithium sulfide, zinc sulfide, silicon powder, and sulfur powder is 7:0.5:1:

6.

3. The method for preparing the coating material as described in claim 1, characterized in that, The inert atmosphere is one of high-purity argon, high-purity nitrogen or a vacuum environment, preferably a vacuum environment with a vacuum degree less than 10⁻ 4 mbar.

4. The method for preparing the coating material as described in claim 1, characterized in that, The heat treatment temperature is 500-1000℃, preferably 700℃; the heat treatment time is 6-30h, preferably 24h; the heat treatment is performed 1-4 times, preferably 2 times.

5. The method for preparing the coating material as described in claim 1, characterized in that, The Al doping source is selected from any one or more of the following: AlCl3, LiAlS2, Al2S3, Al2O3, Al(OH)3, Al(NO3)3, Al2(SO4)3, Al(OiPr)3, Al(acac)3 or their lithium complexes; the Cl doping source is selected from any one or more of the following: LiCl, NaCl, KCl, MgCl2, CaCl2, AlCl3, NH4Cl or chlorine-containing organic salts (such as acetyl chloride, isopropyl trichloride), and the above doping sources can be used alone or in combination.

6. The method for preparing the coating material as described in claim 1, characterized in that, The Al:Si molar ratio is controlled at 0.005~0.1:1, preferably 0.03:1; the Cl:S molar ratio is controlled at 0.015~0.10:1, preferably 0.06:

1.

7. The method for preparing the coating material as described in claim 1, characterized in that, In step S2, the ratio of powder to CNT is 1:0.05~0.3, preferably 1:

01.

8. A coating material, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. A coated and modified cathode material and its battery, characterized in that, The cathode material includes a substrate and a coating layer, the coating layer being located on at least a portion of the surface of the substrate; the substrate is a ternary cathode material, and the coating layer is made of the coating material as described in claim 8; the battery includes the coated and modified cathode material.

10. The method for preparing the coated and modified cathode material as described in claim 8, characterized in that, include: The matrix and the coating material are mixed and sintered under an inert atmosphere; wherein the mass ratio of the coating material to the matrix is ​​0.1:3~100; the sintering temperature is 250-600 ℃ and the sintering time is 2-10 h.

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