Cathode material with cl-o gradient distribution core-shell structure, preparation method and application thereof

Abstract

This invention provides a cathode material with a Cl-O gradient core-shell structure, its preparation method, and its applications. The cathode material includes a cathode material matrix core and a Li-M-N-O-Cl shell covering the surface of the cathode material matrix core. In the Li-M-N-O-Cl shell, the oxygen content decreases and the chlorine content increases along the direction from the cathode material matrix core to the shell surface, forming a Cl-O gradient distribution structure with an oxygen-rich interior and a Cl-rich exterior. This invention achieves functional synergy by constructing a Cl-O gradient core-shell structure with an oxygen-rich interior and a Cl-rich exterior: the oxygen-rich inner layer enhances interfacial compatibility and bonding force with the cathode matrix, suppresses volume expansion and element interdiffusion at the interface, while the Cl-rich outer layer reduces interfacial tension, decreases chemical reactions at the interface, and improves ionic conductivity and solid-solid contact.

Description

Technical Field

[0001] This invention belongs to the field of all-solid-state battery technology, specifically relating to cathode materials with a Cl-O gradient core-shell structure and their preparation method, as well as the application of the cathode material in all-solid-state batteries, particularly in sulfide all-solid-state batteries. Background Technology

[0002] All-solid-state batteries are considered a crucial development direction for next-generation power batteries due to their outstanding advantages such as high energy density and excellent safety. Among them, sulfide electrolytes have attracted significant attention due to their high ionic conductivity and good processing performance. However, sulfide electrolytes and traditional cathode materials (such as LiCoO2, LiNi...)... 1-x-y Co x Mn y There are serious interface compatibility issues among sulfide-based all-solid-state batteries (such as O2 and LiFePO4), which restrict the performance improvement and commercial application of these batteries.

[0003] Patent application CN115275128A employs a combination of manual grinding and mechanical ball milling to coat the surface of a ternary cathode material with a high-ionic-conductivity halide solid electrolyte, Li2ZrCl6, aiming to utilize its excellent ionic / electronic conductivity to suppress interfacial side reactions under high voltage. However, mechanical grinding is essentially a physical mixing process, making it difficult to achieve uniform and continuous coating at the nanoscale. This can easily lead to localized deficiencies or agglomeration of the coating layer, thus failing to effectively isolate the direct contact between the cathode and the sulfide electrolyte. More importantly, the mechanical stress generated during high-intensity grinding can easily cause lattice distortion, microcracks, or even breakage on the surface of the cathode particles, not only damaging the integrity of the material structure but also potentially exposing new active sites, thereby exacerbating interfacial side reactions.

[0004] Patent application CN120453350A discloses a composite polycrystalline cathode material. This material achieves uniform coating of the polycrystalline cathode material surface and grain boundaries by melting and infiltrating a halide oxide solid electrolyte onto the surface. This method effectively improves the capacity utilization of the active material and reduces interfacial impedance. However, this patented technology achieves ion conduction and interfacial barrier functions with only a single component, making it difficult to simultaneously meet the different requirements of the cathode side and the sulfide electrolyte side. Furthermore, during subsequent charge-discharge cycles, cracking easily occurs at the interface between the uniform coating layer and the cathode material and electrolyte.

[0005] Patent CN120565787A discloses a method for sintering LiAl at low temperature (<280°C) to form LiAl. a Cl b O cThe method of in-situ melting and coating of chlorine oxide solid electrolyte onto the surface of cathode particles aims to achieve a more uniform coating effect than ball milling and avoid problems such as high-temperature oxygen release or polymer solvent degradation. However, this method has the following limitations: First, low-temperature melting and coating depends on the thermal fluidity of the material, and its uniformity is constrained by factors such as melt wettability, particle packing density, and sintering time. It is difficult to form a completely continuous, pore-free conformal coating at the nanoscale, especially in high specific surface area or porous cathode materials, where local coverage gaps are prone to occur. Second, the chlorine oxide coating layer has a homogeneous structure, which makes it impossible to actively control the spatial distribution of elements and to simultaneously meet the interfacial compatibility requirements of the cathode side and the sulfide solid electrolyte side.

[0006] Therefore, developing a coating layer structure with a gradient composition to achieve synergistic optimization of different functions is crucial for improving the rate performance of sulfide all-solid-state batteries, enhancing battery cycle stability, and ultimately leveraging the advantages of high energy density and high safety performance of solid-state batteries. Summary of the Invention

[0007] The present invention aims to solve the above-mentioned problems of the prior art, and its purpose is to provide a cathode material with a Cl-O gradient core-shell structure, its preparation method and application.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, a cathode material with a Cl-O gradient core-shell structure is provided, comprising a cathode material matrix core and a Li-MNO-Cl shell covering the surface of the cathode material matrix core; in the Li-MNO-Cl shell, the oxygen content decreases and the chlorine content increases in the direction from the cathode material matrix core to the shell surface, forming a Cl-O gradient distribution structure with an oxygen-rich interior and a Cl-rich exterior.

[0009] Furthermore, M and N are each independently selected from one or more of Zr, Sc, Y, La-Lu, Al, Ga, In, Ti, V, Cr, Mn, Fe, Co, Zn, Mg, and Cu.

[0010] Furthermore, the general formula of the Li-MNO-Cl shell is Li a M b N c OCl d Where 0.5≤a≤3, 0≤b≤3, 0≤c≤3, 0.5≤b+c≤6, and 4≤d≤6.

[0011] Furthermore, the cathode material matrix core is LiFePO4, LiCoO2, or LiNi. x Co y Mn 1-x-y O2, LiNix Co y Al 1-x-y One or more mixtures of O2, zLi2MnO3·(1 - z)LiTMO2, where TM is one or more mixtures of transition metals Ni, Co, Mn, 0 < x < 1, 0 < y < 1 and x + y < l, 0 ≤ z ≤ 1.

[0012] Furthermore, the thickness of the Li - M - N - O - Cl shell is 1 - 50 nm, preferably 5 - 20 nm.

[0013] Furthermore, the mass fraction of oxygen element in the inner surface of the Li - M - N - O - Cl shell close to the cathode material matrix core is 40 - 60%; the mass fraction of oxygen element in the outer surface of the Li - M - N - O - Cl shell far from the cathode material matrix core is 10 - 30%.

[0014] Furthermore, the mass fraction of chlorine element in the inner surface of the Li - M - N - O - Cl shell close to the cathode material matrix core is 10 - 30%; the mass fraction of oxygen element in the outer surface of the Li - M - N - O - Cl shell far from the cathode material matrix core is 40 - 60%.

[0015] Furthermore, the cathode material is spherical or quasi - spherical particles; the particle size of the cathode material is 1 - 10 μm.

[0016] Furthermore, in the direction from the cathode material matrix core to the shell surface, the content of oxygen element gradually decreases, and the content of chlorine element gradually increases.

[0017] In the second aspect, a preparation method of a cathode material with a Cl - O gradient - distribution core - shell structure is provided, including: S1. Pretreatment and Li deposition: Place the cathode material in an atomic layer deposition reaction chamber, perform heat pretreatment under an inert atmosphere, and then introduce the Li source into the reaction chamber in the form of pulses to deposit a Li - containing layer on the surface of the cathode material; S2. Construct a oxygen - rich inner layer: Introduce MCl e and O3 into the reaction chamber in an alternating - pulse manner for the first deposition; where the pulse time of MCl e is 0.1 - 0.5 s, the pulse interval is 5 - 10 s, the pulse time of O3 is 1 - 5 s, the pulse interval is 5 - 10 s, and each deposition cycle includes one MCl e pulse and one O3 pulse; A number of cycles are deposited in this stage to form an oxygen - rich inner - layer structure on the surface of the cathode material; S3. Construct a Cl - rich outer layer: Introduce NCl fAnd O3, to carry out a second deposition; in which NCl f The pulse duration is 0.5–2 s, and the pulse interval is 5–10 s. The O3 pulse duration is 0.1–1 s, and the pulse interval is 5–10 s. Each deposition cycle includes one NCl-particle deposition. f The process involves a pulse and an O3 pulse; this stage deposits for several cycles, forming a Cl-rich outer layer on the surface of the inner layer structure.

[0018] Thirdly, a solid-state lithium-ion battery is provided, comprising the cathode material with a Cl-O gradient distribution core-shell structure as described in the first aspect or the cathode material with a Cl-O gradient distribution core-shell structure prepared by the preparation method described in the first aspect.

[0019] Compared with the prior art, one or more of the above technical solutions can achieve at least one of the following beneficial effects: (1) Compared with a single coating structure, the Cl-O gradient distribution core-shell structure constructed by the present invention, which is internally oxygen-rich and externally Cl-rich, achieves functional synergy: the oxygen-rich region inside the shell has good chemical compatibility and bonding force with the positive electrode core phase, which can effectively suppress the volume expansion of the positive electrode material during charging and discharging, reduce the generation of interface cracks, and effectively suppress the interdiffusion phenomenon of elements at the interface of the positive electrode / sulfide solid electrolyte; the Cl-rich region outside the shell has similar chemical properties to the sulfide electrolyte, which can reduce the interfacial tension and reduce the occurrence of interfacial chemical reactions. Moreover, the relatively soft nature of chloride can effectively alleviate the problem of poor solid-solid contact in solid batteries. At the same time, the introduction of chlorine can improve the ionic conductivity of the shell and ensure the rapid transport of ions at the interface.

[0020] (2) The core-shell structure prepared by ALD technology can precisely control the thickness and composition distribution of the shell layer, ensuring the uniformity and density of the coating layer and avoiding problems such as incomplete coating and uneven thickness in traditional coating methods. By adjusting the pulse time and deposition cycle of metal chloride and O3, the Cl-O gradient distribution can be precisely controlled to meet the needs of different cathode materials and electrolyte systems. Moreover, by independently introducing an O3 source to achieve precise construction of the Cl-O gradient, oxygen can be removed from the cathode material by destroying the cathode lattice, thereby avoiding excessive damage to the interface. This allows the crystal structure and electrochemical activity of the cathode material itself to be preserved to the greatest extent while obtaining the Cl-O gradient structure.

[0021] (3) This invention employs a solvent-free, low-temperature ALD process, which has several significant advantages over traditional solid-state sintering or wet chemical coating methods. First, the entire process does not require the use of any organic or aqueous solvents, fundamentally avoiding side reactions such as hydrolysis and oxidation that occur after the chloride precursor comes into contact with the solvent, thereby preventing the formation of interfacial impurities and a decrease in lithium-ion conductivity. Second, the low processing temperature effectively avoids common problems in chloride materials during high-temperature heat treatment, such as metal-chlorine bond breakage, elemental segregation, and Cl volatilization, eliminating defects such as uneven coating composition, pores, or discontinuities caused by the separation and enrichment of Cl and metal elements, significantly improving the uniformity, density, and chemical stability of the coating. This invention achieves stable deposition of chloride systems at low temperatures, retaining the unique advantages of high ionic conductivity and low hardness of chlorides.

[0022] (4) The preparation method of the present invention is simple and highly controllable, and is suitable for large-scale industrial production, providing effective technical support for the performance improvement of sulfide all-solid-state batteries. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The above are the rate performance diagrams for Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3.

[0025] Figure 2 This is a comparison graph of the cyclic stability of Example 1 and Comparative Example 3. Detailed Implementation

[0026] Some embodiments of the present invention provide a cathode material with a Cl-O gradient core-shell structure, comprising a cathode material matrix core and a Li-MNO-Cl shell covering the surface of the cathode material matrix core; in the Li-MNO-Cl shell, the oxygen content decreases and the chlorine content increases in the direction from the cathode material matrix core to the shell surface, forming a Cl-O gradient distribution structure with an oxygen-rich interior and a Cl-rich exterior.

[0027] In some preferred embodiments, the general formula of the Li-MNO-Cl shell is Li a M b N c OCl dWhere 0.5≤a≤3, for example 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, etc., and 0≤b≤3, for example 0, 0. 1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, etc., where 0 ≤ c ≤ 3, for example, 0, 0. 1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 , 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, etc., 0.5≤b+c≤6, for example Values ​​can be 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, 6, etc., where 4 ≤ d ≤ 6. For example, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, 6, etc. The values ​​of a, b, c, and d must conform to the principle of valence balance to ensure that the compound is electrically neutral and has a stable composition and structure.

[0028] In some preferred embodiments, the oxygen content gradually decreases and the chlorine content gradually increases along the direction from the core to the shell surface of the cathode material matrix. This continuous gradient composition structure has the following core advantages: 1. It can eliminate interfacial stress concentration: The continuous change in composition avoids abrupt changes in lattice constant and thermal expansion coefficient, and uniformly disperses the stress generated during charging and discharging in the transition region, effectively suppressing interfacial cracks and coating peeling, and improving cycle stability; 2. It can achieve smooth functional synergy: The oxygen-rich inner layer ensures compatibility with the cathode core and suppresses element interdiffusion, while the chlorine-rich outer layer ensures interfacial affinity with the sulfide electrolyte and high ionic conductivity. The gradient transition region allows the two functions to be seamlessly connected, avoiding functional cliffs and impedance increases at abrupt interfaces; 3. It can optimize ion transport paths: The continuous gradient forms a smooth chemical potential field within the coating layer, reducing the activation energy of lithium ion migration, guiding ions to efficiently pass through the coating layer, and improving rate performance and low-temperature performance.

[0029] In some preferred embodiments, M and N are each independently selected from one or more of Zr, Sc, Y, La-Lu, Al, Ga, In, Ti, V, Cr, Mn, Fe, Co, Zn, Mg, and Cu.

[0030] In some embodiments, when the M and M elements are elements with a valence of +2 to +4, 1.25 ≤ b + c ≤ 5.75.

[0031] In some preferred embodiments, the cathode material matrix core is one or more of LiFePO4, LiCoO2, LiNi x Co y Mn 1-x- y O2, LiNi x Co y Al 1-x-y O2, a mixture of one or more of zLi2MnO3·(1 - z)LiTMO2, where TM is a mixture of one or more of the transition metals Ni, Co, Mn, 0 < x < 1, 0 < y < 1 and x + y < 1, 0 ≤ z ≤ 1.

[0032] In some preferred embodiments, the thickness of the Li - M - N - O - Cl shell is 1 to 50 nm, preferably 5 to 20 nm.

[0033] In some preferred embodiments, the mass fraction of oxygen in the inner surface of the Li - M - N - O - Cl shell close to the cathode material matrix core is 40 to 60%, such as 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, etc.; the mass fraction of oxygen in the outer surface of the Li - M - N - O - Cl shell far from the cathode material matrix core is 10 to 30%, such as 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, etc.

[0034] In some preferred embodiments, the mass fraction of chlorine in the inner surface of the Li - M - N - O - Cl shell close to the cathode material matrix core is 10 to 30%, such as 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, etc.; the mass fraction of oxygen in the outer surface of the Li - M - N - O - Cl shell far from the cathode material matrix core is 40 to 60%, such as 40%, 42%, 45%, 48%, 5�%, <<52>>, 55%, 58%, 60%, etc.

[0035] In some preferred embodiments, the cathode material is spherical or quasi - spherical particles; the particle size of the cathode material is 1 to 10 μm.

[0036] Some embodiments of the present invention provide a method for preparing a cathode material having a Cl - O gradient - distributed core - shell structure, including: S1. Pretreatment and Li Deposition: The cathode material is placed in an atomic layer deposition reaction chamber and pretreated by heating under an inert atmosphere. Then, a Li source is introduced into the reaction chamber in a pulsed manner to deposit a Li-containing layer on the surface of the cathode material. In this process, a lithium source, such as an organolithium compound or a lithium complex, is introduced into the reaction chamber in a pulsed manner to form a Li-containing layer on the surface of the cathode material, which is chemically bonded to the substrate surface, for example, forming a surface-O-Li structure, providing reaction sites for the subsequent introduction of metal chlorides and ozone. S2. Constructing an oxygen-rich inner layer: MCl is introduced into the reaction chamber using alternating pulses. e (i.e., chloride of M) and O3, for the first deposition; wherein, MCl e The pulse duration is 0.1~0.5s, such as 0.1s, 0.2s, 0.3s, 0.4s, 0.5s, etc., and the pulse interval is 5~10s, such as 5s, 6s, 7s, 8s, 9s, 10s, etc. The O3 pulse duration is 1~5s, such as 1s, 2s, 3s, 4s, 5s, etc., and the pulse interval is 5~10s, such as 5s, 6s, 7s, 8s, 9s, 10s, etc. Each deposition cycle includes one MCl. e A pulse and a single O3 pulse; this stage involves deposition over several cycles, forming an oxygen-rich inner layer structure on the surface of the cathode material; in this step, chloride MCl... e It can react with -O-Li groups, and its strong oxidizing properties cause a large number of M-Cl bonds to be converted into MO bonds. Due to the relatively long O3 pulse time and strong O3 oxidizing power, the film deposited at this stage has relatively little residual Cl and is generally in an oxygen-rich state; at the same time, the Li generated in the previous reaction... + Unreacted Li species may be doped into the gaps in the MO lattice or amorphous network, forming Li-MO-Cl regions.

[0037] S3. Constructing a Cl-rich outer layer: NCl is introduced into the reaction chamber using alternating pulses. f And O3, to carry out the second deposition; in this stage, NCl f The pulse duration (i.e., N chloride) is 0.5~2s, e.g., 0.5s, 0.6s, 0.7s, 0.8s, 0.9s, 1s, 1.1s, 1.2s, 1.3s, 1.4s, 1.5s, 1.6s, 1.7s, 1.8s, 1.9s, 2s, etc., with a pulse interval of 5~10s, e.g., 5s, 6s, 7s, 8s, 9s, 10s, etc. The O3 pulse duration is 0.1~1s, e.g., 0.1s, 0.2s, 0.3s, 0.4s, 0.5s, 0.6s, 0.7s, 0.8s, 0.9s, 1s, etc., with a pulse interval of 5~10s, e.g., 5s, 6s, 7s, 8s, 9s, 10s, etc.; each deposition cycle includes one NCl... fA pulse and a single O3 pulse; this stage involves deposition over several cycles, forming a Cl-rich outer layer on the surface of the inner layer structure. In this step, NCl... f The NCl reacts with the surface groups at the terminal of step S2 to generate a Li-ON-Cl structure. Simultaneously, due to the Li-MO network on the inner surface of step S2, NCl... f It may undergo partial cation exchange with Li and M or form mixed bonds (such as Li-NM-Cl). A short-term O3 pulse provides limited oxygen, replacing some Cl with O, while a large amount of Cl is retained in the film, forming Li-NMO-Cl and Li-NO-Cl.

[0038] In the provided preparation process, on the one hand, because atomic layer deposition (ALD) technology is based on a self-limiting reaction mechanism, its nucleation and growth process strictly depends on the active sites on the substrate surface. Therefore, during the process of layer-by-layer deposition from the core of the material substrate outward, a nucleation and growth gradient distributed along the thickness direction will naturally form. Thus, the composition distribution of Cl and O shows a gradual change characteristic with the deposition cycle. On the other hand, because spontaneous diffusion will occur at the junction of the two coating layers formed in steps S2 and S3, in the synthesized cathode material, the oxygen content gradually decreases and the chlorine content gradually increases along the direction from the core of the cathode material substrate to the shell surface.

[0039] In some preferred embodiments, the lithium source is one or a mixture of two or more of lithium tert-butoxide and lithium 2,2,6,6-tetramethyl-3,5-heptadecylene.

[0040] In some preferred embodiments, MCl e and NCl f In this mixture, M and N are each independently selected from one or more of Zr, Sc, Y, La-Lu, Al, Ga, In, Ti, V, Cr, Mn, Fe, Co, Zn, Mg, and Cu; preferably, MCl e and NCl f It is one or a mixture of two or more of the following: titanium tetrachloride (TiCl4), tin tetrachloride (SnCl4), gallium trichloride (GaCl3), cuprous chloride (CuCl), aluminum trichloride (AlCl3), ferric chloride (FeCl3), and tantalum pentachloride (TaCl5).

[0041] In some preferred embodiments, the oxygen-enriched inner layer structure has an oxygen mass fraction of 40-60%, such as 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, etc., and a chlorine mass fraction of 10-30%, such as 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, etc.

[0042] In some preferred embodiments, the Cl-rich outer layer structure has a chlorine mass fraction of 40-60%, such as 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, etc., and an oxygen mass fraction of 10-30%, such as 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, etc.

[0043] In some preferred embodiments, in step S1, the pulse duration of the lithium source is 1 to 5 seconds, such as 1 second, 2 seconds, 3 seconds, 4 seconds, 5 seconds, etc., and the number of pulses is 1 to 5 times, such as 1 time, 2 times, 3 times, 4 times, 5 times, etc.

[0044] In some preferred embodiments, in step S1, the temperature of the lithium source is 160~180℃, for example, 160℃, 165℃, 170℃, 175℃, 180℃, etc.

[0045] In some preferred embodiments, in step S1, the lithium source is introduced into the reaction chamber via an inert gas load.

[0046] In some preferred embodiments, in step S1, the heating pretreatment time is 45~120 min, for example 45 min, 60 min, 75 min, 90 min, 105 min, 120 min, etc.

[0047] In some preferred embodiments, in step S2, the deposition cycle is 5 to 30 times, for example, 5, 10, 15, 20, 25, 30 times, etc.

[0048] In some preferred embodiments, in step S3, the deposition cycle is 5 to 30 times, for example, 5, 10, 15, 20, 25, 30 times, etc.

[0049] In some preferred embodiments, during steps S1 to S3, when depositing the Li layer, the oxygen-rich inner layer, and the chlorine-rich outer layer on the surface of the positive electrode material, the temperature of the reaction chamber is 240~300℃, preferably 260~280℃.

[0050] In some preferred embodiments, the pressure inside the reaction chamber is 0.5~1MPa, for example 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa, 1MPa, etc.

[0051] In some preferred embodiments, in steps S1 to S3, an inert carrier gas is introduced after each pulse for purging, with each purging time being independently 3 to 10 seconds, to remove unreacted precursor lithium source and MCl from the reaction chamber. e ,NCl f O3 and reaction byproducts.

[0052] Some embodiments of the present invention provide a solid-state lithium-ion battery, including the aforementioned cathode material with a Cl-O gradient core-shell structure or the cathode material with a Cl-O gradient core-shell structure prepared by the aforementioned preparation method.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] Example 1 (1) 5g of positive electrode material LiNi 0.85 Co 0.10 Mn 0.05 O2 was placed in the reaction chamber of the ALD device, the reaction chamber was sealed and evacuated to 0.7 MPa, and the temperature of the reaction chamber was maintained at 270℃ for 60 minutes. Lithium tert-butoxide was then heated to 170℃, and the precursor lithium tert-butoxide was loaded into the reaction chamber using nitrogen (N2). The cathode material LiNi... 0.85 Co 0.10 Mn 0.05 Lithium atoms are deposited on the O2 surface. The pulse duration of lithium tert-butoxide is 3 seconds, and the number of pulses is 3.

[0057] (2) Oxygen-enriched inner layer deposition: After purging excess tert-butoxide lithium with nitrogen (N2), TiCl4 is used as the MCl4 layer. x A metal chloride source was used with a pulse duration of 0.3 s and a pulse interval of 8 s; an O3 source was used with a pulse duration of 3 s and a pulse interval of 8 s; these were alternately deposited for 15 cycles. TEM surface scanning energy dispersive spectroscopy analysis showed that the inner layer contained 53% oxygen and 12% chlorine by mass.

[0058] (3) Deposition of Cl-rich outer layer: TiCl4 pulse time 1s, pulse interval 8s; O3 pulse time 0.5s, pulse interval 8s; 15 deposition cycles. TEM surface scanning energy dispersive spectroscopy showed that the mass fraction of chlorine in the outer layer was 42% and the mass fraction of oxygen was 11%.

[0059] (4) After deposition, the coated cathode material is naturally cooled in the ALD reaction chamber, and the sample is taken out to obtain the target cathode material.

[0060] (5) Take 210 mg of LiNi coated with chlorine oxide 0.85 Co 0.10 Mn 0.05 O2 and 90 mg Li6PS5Cl were ground in a mortar for 10 minutes. The mixture was then transferred to a 2 ml centrifuge tube and further mixed for 6 minutes at 300 rpm to prepare a composite cathode material.

[0061] (6) 10 mg of composite positive electrode material, 85 mg of sulfide solid electrolyte Li6PS5Cl, and lithium indium alloy negative electrode are added to a pressurized battery mold to assemble a sulfide all-solid-state battery.

[0062] Comparative Example 1 (1) 5g of positive electrode material LiNi 0.85 Co 0.10 Mn 0.05 O2 was placed in the reaction chamber of the ALD device, the reaction chamber was sealed and evacuated to 0.7 MPa, and the temperature of the reaction chamber was maintained at 270℃ for 60 minutes. Lithium tert-butoxide was then heated to 170℃, and the precursor lithium tert-butoxide was loaded into the reaction chamber using nitrogen (N2). The cathode material LiNi... 0.85 Co 0.10 Mn 0.05 Lithium atoms are deposited on the O2 surface. The pulse duration of lithium tert-butoxide is 3 seconds, and the number of pulses is 3.

[0063] (2) After purging excess lithium tert-butoxide with nitrogen (N2), TiCl4 is used as the MCl4. x Metal chloride source, pulse time 0.3s, pulse interval 8s; O3 as oxygen source, pulse time 3s, pulse interval 8s; alternating deposition for 30 cycles.

[0064] (3) After deposition, the coated cathode material is naturally cooled in the ALD reaction chamber, and the sample is taken out to obtain the target cathode material.

[0065] (4) Take 210 mg of LiNi coated with chlorine oxide 0.85 Co 0.10 Mn 0.05 O2 and 90 mg Li6PS5Cl were ground in a mortar for 10 minutes. The mixture was then transferred to a 2 ml centrifuge tube and further mixed for 6 minutes at 300 rpm to prepare a composite cathode material.

[0066] (5) 10 mg of composite positive electrode material, 85 mg of sulfide solid electrolyte Li6PS5Cl and lithium indium alloy negative electrode are added to a pressurized battery mold to assemble a sulfide all-solid-state battery.

[0067] Comparative Example 2 (1) 5g of positive electrode material LiNi 0.85 Co 0.10 Mn 0.05 O2 was placed in the reaction chamber of the ALD device, the reaction chamber was sealed and evacuated to 0.7 MPa, and the temperature of the reaction chamber was maintained at 270℃ for 60 minutes. Lithium tert-butoxide was then heated to 170℃, and the precursor lithium tert-butoxide was loaded into the reaction chamber using nitrogen (N2). The cathode material LiNi... 0.85 Co 0.10 Mn 0.05 Lithium atoms are deposited on the O2 surface. The pulse duration of lithium tert-butoxide is 3 seconds, and the number of pulses is 3.

[0068] (2) After purging excess lithium tert-butoxide with nitrogen (N2), TiCl4 is used as the MCl4. x Metal chloride source, pulse time 1s, pulse interval 8s; O3 pulse time 0.5s, pulse interval 8s; 30 deposition cycles.

[0069] (3) After deposition, the coated cathode material is naturally cooled in the ALD reaction chamber, and the sample is taken out to obtain the target cathode material.

[0070] (4) Take 210 mg of LiNi coated with chlorine oxide 0.85 Co 0.10 Mn 0.05 O2 and 90 mg Li6PS5Cl were ground in a mortar for 10 min. The mixture was then transferred to a 2 mL centrifuge tube and further mixed for 6 min at 300 rpm to prepare a composite cathode material.

[0071] (5) 10 mg of composite positive electrode material, 85 mg of sulfide solid electrolyte Li6PS5Cl and lithium indium alloy negative electrode are added to a pressurized battery mold to assemble a sulfide all-solid-state battery.

[0072] Comparative Example 3 (1) Take 210 mg of uncoated LiNi 0.85 Co 0.10 Mn 0.05 O2 and 90 mg Li6PS5Cl were ground in a mortar for 10 minutes. The mixture was then transferred to a 2 ml centrifuge tube and further mixed for 6 minutes at 300 rpm to prepare a composite cathode material.

[0073] (2) 10 mg of composite positive electrode material, 85 mg of sulfide solid electrolyte Li6PS5Cl, and lithium indium alloy negative electrode are added to a pressurized battery mold to assemble a sulfide all-solid-state battery.

[0074] Comparative Example 4 This comparative example describes the preparation of a chloride-coated cathode material using a traditional solid-state sintering coating method, followed by the assembly of a sulfide all-solid-state battery. The preparation method includes: (1) After mixing Li2O2 and TiCl4 in a mortar at a molar ratio of 1:1, the mixture was vacuum sealed and heated to 300°C at a heating rate of 5°C / min. The mixture was then kept at this temperature for 24 hours and allowed to cool naturally to room temperature to obtain the coating material Li2TiO2Cl4.

[0075] (2) LiNi 0.85 Co 0.10 Mn 0.05 O2 and the coating material Li2TiO2Cl4 obtained in step (1) were mixed evenly at a mass ratio of 100:1, then vacuum sealed. The mixture was heated to 550°C at a heating rate of 5°C / min, held at that temperature for 5 hours, and then naturally cooled to room temperature to obtain LiNi coated with Li-Ti-O-Cl chlorine oxides. 0.85 Co 0.10 Mn 0.05 O2 cathode material.

[0076] (3) Take 210 mg of LiNi coated with chlorine oxide 0.85 Co 0.10 Mn 0.05 O2 and 90 mg Li6PS5Cl were ground in a mortar for 10 minutes. The mixture was then transferred to a 2 ml centrifuge tube and further mixed for 6 minutes at 300 rpm to prepare a composite cathode material.

[0077] (4) 10 mg of composite positive electrode material, 85 mg of sulfide solid electrolyte Li6PS5Cl, and lithium indium alloy negative electrode are added to a pressurized battery mold to assemble a sulfide all-solid-state battery.

[0078] Comparative Example 5 (1) LiNi 0.85 Co 0.10 Mn 0.05 O2 and Li2O2 were mixed uniformly at a mass ratio of 100:0.5, then vacuum-sealed. The mixture was heated to 550°C at a rate of 5°C / min, held at that temperature for 5 hours, and then naturally cooled to room temperature to obtain LiNi coated with Li2O oxide. 0.85 Co 0.10 Mn 0.05 O2 cathode material.

[0079] (2) The LiNi oxide coated with the Li2O obtained in step (1) 0.85 Co 0.10 Mn 0.05 O2 cathode material and TiCl4 were mixed uniformly at a mass ratio of 100:0.5 and then vacuum-sealed. The mixture was heated to 550℃ at a heating rate of 5℃ / min, held at that temperature for 5 hours, and then naturally cooled to room temperature to obtain LiNi oxide coated with a gradient distribution of Li-Ti-O-Cl chloride oxides. 0.85 Co 0.10 Mn 0.05 O2 cathode material.

[0080] (3) Take 210 mg of LiNi coated with chlorine oxide in a gradient distribution. 0.85 Co 0.10 Mn 0.05 O2 and 90 mg Li6PS5Cl were ground in a mortar for 10 minutes. The mixture was then transferred to a 2 ml centrifuge tube and further mixed for 6 minutes at 300 rpm to prepare a composite cathode material.

[0081] (4) 10 mg of composite positive electrode material, 85 mg of sulfide solid electrolyte Li6PS5Cl, and lithium indium alloy negative electrode are added to a pressurized battery mold to assemble a sulfide all-solid-state battery.

[0082] Example 2 (1) Place 5g of positive electrode material LiNiO2 in the reaction chamber of the ALD device, seal the reaction chamber and evacuate to 0.9MPa. When the temperature of the reaction chamber reaches 280℃, keep it at that temperature for 60min. Heat 2,2,6,6-tetramethyl-3,5-heptadecyl lithium to 175℃, and load the precursor 2,2,6,6-tetramethyl-3,5-heptadecyl lithium into the reaction chamber using helium gas. 0.85 Co 0.10 Mn 0.05 Lithium atoms were deposited on the O2 surface. Among them, the pulse duration of lithium 2,2,6,6-tetramethyl-3,5-heptadecylone was 4 s and the number of pulses was 2.

[0083] (2) Oxygen-enriched inner layer deposition: After purging excess 2,2,6,6-tetramethyl-3,5-heptadecyl lithium with helium, AlCl3 was used as the MCl2 layer. x A metal chloride source was used with a pulse duration of 0.4 s and a pulse interval of 7 s; an O3 source was used with a pulse duration of 2 s and a pulse interval of 7 s; these were alternately deposited for 20 cycles. TEM surface scanning energy dispersive spectroscopy analysis showed that the inner layer contained 48% oxygen and 13% chlorine by mass.

[0084] (3) Deposition of Cl-rich outer layer: AlCl3 pulse time 1.5s, pulse interval 7s; O3 pulse time 0.7s, pulse interval 7s; 20 deposition cycles. TEM surface scanning energy dispersive spectroscopy showed that the mass fraction of chlorine in the outer layer was 45% and the mass fraction of oxygen was 22%.

[0085] (4) After deposition, the coated cathode material is naturally cooled in the ALD reaction chamber, and the sample is taken out to obtain the target cathode material.

[0086] (5) Take 210 mg of LiNi coated with chlorine oxide 0.85 Co 0.10 Mn 0.05 O2 and 90 mg Li6PS5Cl were ground in a mortar for 10 minutes. The mixture was then transferred to a 2 ml centrifuge tube and further mixed for 6 minutes at 300 rpm to prepare a composite cathode material.

[0087] (6) 10 mg of composite positive electrode material, 85 mg of sulfide solid electrolyte Li6PS5Cl, and lithium indium alloy negative electrode are added to a pressurized battery mold to assemble a sulfide all-solid-state battery.

[0088] Comparative Example 6 This comparative example describes the preparation of a chlorine oxide-coated cathode material using a traditional mechanical grinding method, followed by the assembly of a sulfide all-solid-state battery. The preparation method includes: (1) Weigh Li2O2 and AlCl3 in a glove box at a molar ratio of 1:1, then add the reactant raw materials into a ball mill jar and ball mill at 500 rpm for 5 h to obtain chlorine oxide Li2AlO2Cl3 coated material.

[0089] (2) Continue to add LiNiO2 to the ball mill jar at a total mass ratio of 100:1.5 between LiNiO2 and the coating material, and ball mill at 200 rpm for 5 h to obtain LiNiO2 cathode material coated with chlorine oxide.

[0090] (3) Take 210 mg of chlorine oxide-coated LiNiO2 and 90 mg of Li6PS5Cl and grind them in a mortar for 10 min. Transfer the mixture to a 2 ml centrifuge tube and mix it further on a mixer for 6 minutes at a speed of 300 rpm to prepare a composite cathode material.

[0091] (4) 10 mg of composite positive electrode material, 85 mg of sulfide solid electrolyte Li6PS5Cl, and lithium indium alloy negative electrode are added to a pressurized battery mold to assemble a sulfide all-solid-state battery.

[0092] Example 3 (1) Place 5g of positive electrode material LiCoO2 in the reaction chamber of the ALD device, seal the reaction chamber and evacuate to 0.8MPa. When the temperature of the reaction chamber reaches 260℃, keep it at that temperature for 60min. Heat 2,2,6,6-tetramethyl-3,5-heptadecyl lithium to 180℃ and load the precursor 2,2,6,6-tetramethyl-3,5-heptadecyl lithium into the reaction chamber using argon (Ar). 0.85 Co 0.10 Mn 0.05 Lithium atoms were deposited on the O2 surface. Among them, the pulse duration of lithium 2,2,6,6-tetramethyl-3,5-heptadecylone was 2s and the number of pulses was 4.

[0093] (2) Oxygen-enriched inner layer deposition: After purging excess 2,2,6,6-tetramethyl-3,5-heptadecyl lithium with argon (Ar), GaCl3 was used as the MCl2 layer. x A metal chloride source was used with a pulse duration of 0.5 s and a pulse interval of 10 s; an O3 source was used with a pulse duration of 1 s and a pulse interval of 10 s; these alternating deposition cycles were repeated for 10 periods. TEM surface scanning energy dispersive spectroscopy analysis showed that the inner layer contained 41% oxygen and 10% chlorine by mass.

[0094] (3) Deposition of Cl-rich outer layer: TiCl4 pulse time 2s, pulse interval 10s; O3 pulse time 0.5s, pulse interval 10s; 10 deposition cycles. TEM surface scanning energy dispersive spectroscopy showed that the mass fraction of chlorine in the outer layer was 43% and the mass fraction of oxygen was 11%.

[0095] (4) After deposition, the coated cathode material is naturally cooled in the ALD reaction chamber, and the sample is taken out to obtain the target cathode material.

[0096] (5) Take 210 mg of LiNi coated with chlorine oxide 0.85 Co 0.10 Mn 0.05 O2 and 90 mg Li6PS5Cl were ground in a mortar for 10 minutes. The mixture was then transferred to a 2 ml centrifuge tube and further mixed for 6 minutes at 300 rpm to prepare a composite cathode material.

[0097] (6) 10 mg of composite positive electrode material, 85 mg of sulfide solid electrolyte Li6PS5Cl, and lithium indium alloy negative electrode are added to a pressurized battery mold to assemble a sulfide all-solid-state battery.

[0098] Comparative Example 7 (1) Take 210mg of uncoated LiCoO2 and 90mg of Li6PS5Cl and grind them in a mortar for 10min. Transfer the mixture to a 2ml centrifuge tube and mix it further on a mixer for 6min at a speed of 300rpm to prepare a composite cathode material.

[0099] (2) 10 mg of composite positive electrode material, 85 mg of sulfide solid electrolyte Li6PS5Cl, and lithium indium alloy negative electrode are added to a pressurized battery mold to assemble a sulfide all-solid-state battery.

[0100] Example 4 (1) 5g of positive electrode material Li 1.2 Ni 0.2 Mn 0.6 O2 was placed in the reaction chamber of the ALD device, the reaction chamber was sealed and evacuated to 0.5 MPa, and the temperature of the reaction chamber was maintained at 300℃ for 60 minutes. Lithium tert-butoxide was then heated to 165℃, and the precursor lithium tert-butoxide was loaded into the reaction chamber using argon (Ar) gas. The cathode material LiNi... 0.85 Co 0.10 Mn 0.05 Lithium atoms are deposited on the O2 surface. The pulse duration of lithium tert-butoxide is 5 seconds, and the number of pulses is 1.

[0101] (2) Oxygen-enriched inner layer deposition: After purging excess tert-butoxide lithium with argon (Ar), CuCl is used as the MCl. x A metal chloride source was used with a pulse duration of 0.3 s and a pulse interval of 8 s; an O3 source was used with a pulse duration of 3 s and a pulse interval of 8 s; these were alternately deposited for 5 cycles. TEM surface scanning energy dispersive spectroscopy analysis showed that the inner layer contained 58% oxygen and 25% chlorine by mass.

[0102] (3) Deposition of Cl-rich outer layer: TiCl4 pulse time 0.5s, pulse interval 8s; O3 pulse time 0.1s, pulse interval 8s; 5 deposition cycles. TEM surface scanning energy dispersive spectroscopy showed that the mass fraction of chlorine in the outer layer was 51% and the mass fraction of oxygen was 24%.

[0103] (4) After deposition, the coated cathode material is naturally cooled in the ALD reaction chamber, and the sample is taken out to obtain the target cathode material.

[0104] (5) Take 210 mg of LiNi coated with chlorine oxide 0.85 Co 0.10 Mn 0.05 O2 and 90 mg Li6PS5Cl were ground in a mortar for 10 minutes. The mixture was then transferred to a 2 ml centrifuge tube and further mixed for 6 minutes at 300 rpm to prepare a composite cathode material.

[0105] (6) 10 mg of composite positive electrode material, 85 mg of sulfide solid electrolyte Li6PS5Cl, and lithium indium alloy negative electrode are added to a pressurized battery mold to assemble a sulfide all-solid-state battery.

[0106] Comparative Example 8 (1) Take 210 mg of uncoated Li 1.2 Ni 0.2 Mn 0.6 O2 and 90 mg Li6PS5Cl were ground in a mortar for 10 minutes. The mixture was then transferred to a 2 ml centrifuge tube and further mixed for 6 minutes at 300 rpm to prepare a composite cathode material.

[0107] (2) 10 mg of composite positive electrode material, 85 mg of sulfide solid electrolyte Li6PS5Cl, and lithium indium alloy negative electrode are added to a pressurized battery mold to assemble a sulfide all-solid-state battery.

[0108] Solid-state battery performance testing Examples 1-4 and Comparative Examples 1-8 were activated at a current density of 0.1C and then subjected to a constant current charge-discharge test at 0.5C. The test temperature was 25°C. The voltage test range for Examples 1-2 and Comparative Examples 1-6 was 2.7V~4.3V vs Li / Li. + Example 3 and Comparative Example 7: Voltage test range 2.4V~4.45V vs Li / Li + Example 4, Comparative Example 8: Voltage test range 2.6V~4.8V vs Li / Li + Table 1 summarizes the materials, key parameters, and electrochemical performance of each embodiment and comparative example.

[0109] Table 1 As shown in Table 1, the electrochemical performance of the batteries assembled in Examples 1, 3, and 4 is significantly better than that of the batteries assembled in Comparative Examples 3, 7, and 8, respectively. Analysis indicates that this is because the method for preparing the cathode material with a Cl-O gradient core-shell structure provided by this invention can significantly improve the interfacial stability between the cathode material and the sulfide solid electrolyte. Furthermore, the coating material and preparation method proposed in this invention not only facilitate the capacity utilization of various electrode materials in different sulfide all-solid-state batteries but also stabilize the electrode material during cycling, resulting in excellent cycle retention.

[0110] As shown in Table 1, the electrochemical performance of the battery assembled in Example 1 is significantly better than that of the batteries assembled in Comparative Examples 1 and 2. Analysis shows that this is because the core-shell structure with an internal oxygen-rich and external Cl-rich Cl-O gradient distribution constructed in this invention has the following advantages: the higher internal oxygen content helps maintain good compatibility and bonding between the coating layer and the positive electrode substrate; while the higher external chlorine content improves the interfacial compatibility between the shell layer and the sulfide electrolyte and enhances ion transport performance. This structure thus synergistically achieves a dual improvement in interfacial stability and ion conduction efficiency.

[0111] As shown in Table 1, the electrochemical performance of the battery assembled in Example 1 is superior to that of Comparative Example 5. Analysis reveals that although Comparative Example 5 achieves a certain gradient distribution of Cl through in-situ sintering, Example 1's process, through kinetic control and active gradient design, results in a smooth gradient transition, avoiding interface stress concentration. Furthermore, the coating layer composition is precisely controllable. The pre-lithiation layer deposited in the first stage buffers the stress of subsequent deposition layers, improving the interface matching between the cathode material matrix and the coating layer, reducing initial impedance, and exhibiting better coating density and suppression of side reactions. In contrast, the Cl gradient coating layer prepared by Comparative Example 5 through in-situ sintering has difficulty in precisely controlling its thickness, and the coating is prone to island-like growth, resulting in an incomplete coating. Additionally, the uncontrollable diffusion during the thermal diffusion process easily leads to excessive Cl enrichment on the surface, increasing brittleness. Moreover, in-situ sintering coating is prone to problems due to the interaction between lithium oxide coating and subsequent MCl. x Sintering presents an interface matching problem.

[0112] As shown in Table 1, the electrochemical performance of the batteries assembled in Examples 1 and 2 is significantly better than that of the batteries assembled in Comparative Examples 4 and 6, respectively. Analysis shows that this is due to two reasons: firstly, the processes in Examples 1 and 2 are designed with active gradients through kinetic regulation; and secondly, the different preparation processes.

[0113] Rate performance tests were conducted on Examples 1, 1, 2, and 3 at 0.1C, 0.2C, 0.5C, 1C, 2C, and 0.1C, with a test temperature of 25°C and a voltage range of 2.1~3.7V vs Li. x In / Li + This is equivalent to 2.7~4.3V vsLi / Li + The charge / discharge current multiplier (C) is set to 190 mA·g. -1 The result is as follows Figure 1 As shown. Example 1 and Comparative Example 3 were subjected to 100 cycles at a 0.5C rate, as... Figure 2 As shown.

[0114] from Figure 1 and Figure 2As can be seen, compared with Comparative Example 3, the battery assembled in Example 1 exhibits superior rate performance and cycle performance. Analysis revealed that this is due to the coating of the positive electrode active material with a layer of chlorine oxide in Example 1, which isolates the positive electrode material from direct contact with the sulfide solid electrolyte, effectively suppressing decomposition side reactions occurring at their interface during charging and discharging. Furthermore, from... Figure 1 As can be seen, compared with Comparative Example 1 and Comparative Example 2, the battery assembled in Example 1 has better electrochemical performance. This is because the cathode material with Cl-O gradient distribution core-shell structure obtained in the example overcomes the functional limitations of traditional homogeneous coating layers, thereby comprehensively optimizing the overall electrochemical performance of sulfide all-solid-state batteries.

[0115] 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 cathode material with a Cl-O gradient core-shell structure, characterized in that, It includes a positive electrode material matrix core and a Li-MNO-Cl shell covering the surface of the positive electrode material matrix core; in the Li-MNO-Cl shell, the oxygen content decreases and the chlorine content increases in the direction from the positive electrode material matrix core to the shell surface, forming a Cl-O gradient distribution structure with an oxygen-rich interior and a Cl-rich exterior.

2. The cathode material with a Cl-O gradient core-shell structure as described in claim 1, characterized in that, M and N are each independently selected from one or more of Zr, Sc, Y, La-Lu, Al, Ga, In, Ti, V, Cr, Mn, Fe, Co, Zn, Mg, and Cu; The general formula of the Li-MNO-Cl shell is Li a M b N c OCl d Where 0.5≤a≤3, 0≤b≤3, 0≤c≤3, 0.5≤b+c≤6, and 4≤d≤6; The positive electrode material matrix core is one or more mixtures of LiFePO4, LiCoO2, LiNi x Co y Mn 1-x-y O2, LiNi x Co y Al 1-x-y O2, one or more mixtures of zLi2MnO3·(1 - z)LiTMO2, where TM is one or more mixtures of transition metals Ni, Co, Mn, 0 < x < 1, 0 < y < 1 and x + y < 1, 0 ≤ z ≤ 1.

3. The cathode material with a Cl-O gradient core-shell structure as described in claim 1, characterized in that, The thickness of the Li-MNO-Cl shell is 1~50nm, preferably 5~20nm; The oxygen content in the inner surface of the Li-MNO-Cl shell near the cathode material substrate core is 40-60% by mass; the oxygen content in the outer surface of the Li-MNO-Cl shell away from the cathode material substrate core is 10-30% by mass. The mass fraction of chlorine in the inner surface of the Li-MNO-Cl shell near the core of the cathode material is 10-30%; the mass fraction of oxygen in the outer surface of the Li-MNO-Cl shell away from the core of the cathode material is 40-60%.

4. The cathode material with a Cl-O gradient core-shell structure as described in claim 1, characterized in that, The positive electrode material is a spherical or near-spherical particle; the particle size of the positive electrode material is 1~10μm; Along the direction from the core to the shell surface of the cathode material matrix, the oxygen content gradually decreases, while the chlorine content gradually increases.

5. A method for preparing a cathode material with a Cl-O gradient core-shell structure, characterized in that, include: S1. Pretreatment and Li deposition: The cathode material is placed in the atomic layer deposition reaction chamber and pretreated by heating under an inert atmosphere. Then, the Li source is introduced into the reaction chamber in the form of pulses to deposit a Li-containing layer on the surface of the cathode material. S2. Constructing an oxygen-rich inner layer: MCl is introduced into the reaction chamber using alternating pulses. e And O3, for the first deposition; wherein, MCl e The pulse duration is 0.1–0.5 s, and the pulse interval is 5–10 s. The O3 pulse duration is 1–5 s, and the pulse interval is 5–10 s. Each deposition cycle includes one MCl pulse. e The process involves a pulse and a single O3 pulse; this stage involves deposition over several cycles, forming an oxygen-rich inner layer structure on the surface of the cathode material. S3. Constructing a Cl-rich outer layer: NCl is introduced into the reaction chamber using alternating pulses. f And O3, to perform a second deposition; wherein, NCl f The pulse duration is 0.5–2 s, and the pulse interval is 5–10 s. The O3 pulse duration is 0.1–1 s, and the pulse interval is 5–10 s. Each deposition cycle includes one NCl-particle deposition. f The process involves a pulse and an O3 pulse; this stage deposits for several cycles, forming a Cl-rich outer layer on the surface of the inner layer structure.

6. The method for preparing a cathode material with a Cl-O gradient core-shell structure as described in claim 5, characterized in that, The lithium source is one or a mixture of two or more of lithium tert-butoxide and lithium 2,2,6,6-tetramethyl-3,5-heptadecylene. MCl e and NCl f In this mixture, M and N are each independently selected from one or more of Zr, Sc, Y, La-Lu, Al, Ga, In, Ti, V, Cr, Mn, Fe, Co, Zn, Mg, and Cu; preferably, MCl e and NCl f It is one or a mixture of two or more of the following: titanium tetrachloride (TiCl4), tin tetrachloride (SnCl4), gallium trichloride (GaCl3), cuprous chloride (CuCl), aluminum trichloride (AlCl3), ferric chloride (FeCl3), and tantalum pentachloride (TaCl5); In the oxygen-enriched inner structure, the mass fraction of oxygen is 40-60%, and the mass fraction of chlorine is 10-30%. The Cl-rich outer layer structure has a chlorine mass fraction of 40-60% and an oxygen mass fraction of 10-30%.

7. The method for preparing a cathode material with a Cl-O gradient core-shell structure as described in claim 5, characterized in that, In step S1, the pulse duration of the lithium source is 1-5 seconds, and the number of pulses is 1-5 times. In step S1, the temperature of the lithium source is 160~180℃; In step S1, the lithium source is introduced into the reaction chamber via an inert gas load; In step S1, the heating pretreatment time is 45~120 min; In step S2, the deposition cycle is 5 to 30 times; In step S3, the deposition cycle is 5 to 30 times.

8. The method for preparing a cathode material with a Cl-O gradient core-shell structure as described in claim 5, characterized in that, In steps S1 to S3, when depositing the Li layer, the oxygen-rich inner layer and the chlorine-rich outer layer on the surface of the positive electrode material, the temperature of the reaction chamber is 240~300℃, preferably 260~280℃. The pressure inside the reaction chamber is 0.5~1MPa.

9. The method for preparing a cathode material with a Cl-O gradient core-shell structure as described in claim 5, characterized in that, In steps S1 to S3, inert carrier gas is introduced after each pulse for purging, and the purging time is 3 to 10 seconds for each pulse.

10. A solid-state lithium-ion battery, characterized in that, This includes the cathode material with a Cl-O gradient core-shell structure as described in any one of claims 1 to 4, or the cathode material with a Cl-O gradient core-shell structure prepared by the preparation method described in any one of claims 5 to 9.

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