Preparation method of in-situ doped heat-responsive self-sealing high-nickel ternary positive electrode material

Abstract

The application discloses a preparation method of an in-situ doped heat response self-sealing high-nickel ternary positive electrode material, and comprises the following steps: step one, uniformly mixing raw materials including a nickel-cobalt-manganese precursor, a lithium source, a strontium source, a molybdenum source and a solvent to obtain an in-situ doped active core slurry; step two, uniformly mixing raw materials including TEOS, a polymer and a solvent to obtain an interface layer slurry; step three, pouring the in-situ doped active core slurry into the interface layer slurry, uniformly mixing to obtain a core-shell composite slurry; step four, performing spray granulation on the core-shell composite slurry to obtain a granular powder; and step five, performing sintering on the granular powder to obtain the in-situ doped heat response self-sealing high-nickel ternary positive electrode material. The preparation method of the in-situ doped heat response self-sealing high-nickel ternary positive electrode material has the advantages of no need of modifying a precursor, strong industrialization compatibility, and the like, and the prepared material has the advantages of significantly improved thermal safety performance and excellent electrochemical performance.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a method for preparing an in-situ doped thermally responsive self-sealing high-nickel ternary cathode material. Background Technology

[0002] High-nickel ternary cathode material (LiNi) x Co y Mn 1-x-y O2 (x≥0.8) has become a core material for achieving high energy density in lithium-ion batteries due to its ultra-high specific capacity (>200mAh / g). However, the increased nickel content leads to a sharp decline in its thermal stability, and the risk of thermal runaway has become a fatal bottleneck for the industrial application of high-nickel ternary cathode materials. High-nickel ternary cathode materials have a high degree of Ni-O bond hybridization, and lattice oxygen precipitation (accompanied by Ni) easily occurs at relatively low temperatures of around 200℃. 3+ To Ni 2+ The released reactive oxygen species react violently with carbonate solvents in the electrolyte during the reduction process, releasing a large amount of heat (enthalpy change > 2000 J / g). This forms an irreversible chain cycle of "oxygen evolution - exothermic reaction - rapid temperature rise," ultimately triggering thermal runaway. More critically, during charge-discharge cycling, the H2→M→H3 phase transition in high-nickel ternary cathode materials induces stress concentration within the particles, generating numerous microcracks (cracking rate > 30% after 100 cycles). These cracks not only significantly increase the contact area between the material and the electrolyte, accelerating interfacial side reactions, but also become rapid conduction channels for heat and reactive oxygen species, causing localized thermal runaway to spread rapidly throughout the entire electrode, further exacerbating safety risks.

[0003] Existing protection technologies have inherent flaws: First, while passive flame-retardant strategies (such as adding flame retardants to the electrolyte) can delay the thermal runaway process to some extent, they cannot prevent the release of lattice oxygen and will cause the battery's ionic conductivity to decrease by more than 20%, sacrificing electrochemical performance. Traditional surface coating technologies (such as Al2O3 and Li2ZrO3 coatings) can isolate some interfacial reactions, but the lattice mismatch between the coating layer and the substrate is high (>5%), making it prone to detachment and failure during cycling. Furthermore, they cannot seal cracks generated by particles at high temperatures, making it difficult to prevent the release of active oxygen. On the other hand, thermal isolation designs at the battery pack level (such as aerogels and metal separators) are "post-hoc protection" and cannot suppress the thermal runaway triggering of the electrode materials themselves from the source. They also increase the battery's volume and weight, reducing energy density.

[0004] Therefore, developing a high-nickel cathode material that can synergistically solve the thermal runaway problem from three dimensions—"inhibiting lattice oxygen evolution at the source, blocking reactive oxygen diffusion during the process, and isolating heat transfer during propagation"—without sacrificing electrochemical performance has become the key to breaking through the current technological bottleneck.

[0005] Existing technologies have many limitations in addressing the thermal runaway problem of high-nickel ternary cathode materials, failing to provide effective protection across the entire chain. At the source suppression level, traditional doping techniques (such as single Al)... 3+ Zr 4+ Doping can only slightly improve the stability of Ni-O bonds and cannot fundamentally suppress the precipitation of lattice oxygen at high temperatures. The increase in thermal runaway trigger temperature is limited (usually <220℃), which is insufficient to meet the safety requirements of practical applications. Regarding process blocking, existing interface layers are mostly static structures without temperature response capabilities. At high temperatures, they cannot promptly seal microcracks generated by particles during cycling, allowing active oxygen to still leak out through cracks and react with the electrolyte. Furthermore, the interface layers often use inert materials, which hinder lithium-ion transport, leading to a decrease in battery rate performance (5C capacity retention <80%). In terms of thermal propagation containment, existing technologies do not consider precise thermal isolation design between particles. After a single particle triggers thermal runaway, heat and active oxygen rapidly diffuse to surrounding particles, causing a chain reaction of thermal runaway across the entire electrode and even the entire battery pack, lacking effective isolation capabilities for localized risks. In addition, existing protection strategies generally suffer from poor performance synergy, often at the expense of battery electrochemical performance. For example, flame retardants reduce ion conduction efficiency, and thick coating layers sacrifice material specific capacity. They cannot achieve a synergistic improvement of "high energy density-high thermal safety-long cycle life" and are difficult to adapt to the actual application needs of high energy density batteries. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing in-situ doped thermally responsive self-sealing high-nickel ternary cathode materials. This invention is achieved using the following technical solution: A method for preparing an in-situ doped thermally responsive self-sealing high-nickel ternary cathode material includes the following steps: Step 1: Mix the raw materials containing nickel-cobalt-manganese precursor, lithium source, strontium source, molybdenum source and solvent evenly to obtain in-situ doped active nucleus paste; Step 2: Mix the raw materials containing TEOS, polymer and solvent evenly to obtain the interface layer slurry; Step 3: Pour the in-situ doped active core slurry into the interface layer slurry and mix evenly to obtain a core-shell composite slurry; Step 4: Spray granulation of the core-shell composite slurry to obtain particulate powder; Step 5: Sinter the granular powder to obtain the in-situ doped thermally responsive self-sealing high-nickel ternary cathode material.

[0007] Optionally, the nickel-cobalt-manganese precursor has the chemical formula Ni x Co y Mn 1-x-y(OH)2; wherein 0.85≤x≤0.92, 0.04≤y≤0.08, x+y≤1; the nickel-cobalt-manganese precursor has a particle size of 2~4μm.

[0008] Optionally, in step one, the molar ratio of lithium to nickel-cobalt-manganese precursor is 1.03 to 1.05:1.

[0009] Optionally, in step one, Sr² + The doping concentration is 0.4~0.6 at%; Mo 6+ The doping amount is 0.15~0.25 at%.

[0010] Preferred, Sr 2+ Mo 6+ The ratio is 2.8~3.2:1.

[0011] Optionally, in step one, the solvent is at least one of NMP, DMAc, DMSO, and DMF, and the solid content of the in-situ doped active nucleus slurry is 45-55 wt%.

[0012] Optionally, in step two, the solvent is at least one of ethanol, methanol, and isopropanol; and the mass ratio of TEOS:polymer:solvent in step two is 2.5~3.5:2:45~55. Optionally, the polymer is at least one of PEGDE, PVP, PVA, and PAA; Preferably, the pH of the interface layer slurry is 3.0 to 4.0.

[0013] Optionally, the particle size of the powder is 5~8μm.

[0014] Optionally, the sintering process includes: heating to 340-360°C at a rate of 4-6°C / min in an air atmosphere and holding for 3.5-4.5 hours; continuing to heat to 880-920°C at a rate of 4-6°C / min and holding for 9-11 hours in an oxygen atmosphere; then cooling to 190-210°C and holding for 1.5-2.5 hours, followed by natural cooling.

[0015] This invention also proposes an in-situ doped thermally responsive self-sealing high-nickel ternary cathode material prepared by the above method.

[0016] This invention also proposes the application of the above-mentioned doped thermally responsive self-sealing high-nickel ternary cathode material in lithium batteries.

[0017] The present invention has the following beneficial effects: 1. The preparation method of this invention does not require modification of the precursor, has strong industrial compatibility, and can directly use commercially available high-nickel precursors without any crushing, doping, or modification treatment. It perfectly adapts to the dependence on ready-made precursors in the production of existing high-nickel ternary cathode materials, avoids the complex adjustments to the precursor preparation process of traditional doping technology, has small process modifications, low cost, and is easy to scale up for mass production.

[0018] 2. The thermal safety performance of the material of the present invention is significantly improved: by “sintering in-situ doping to strengthen Ni-O bonds”, the lattice oxygen evolution is suppressed from the source, and by “high temperature sealing of cracks in the thermal response interface layer”, the diffusion of active oxygen is blocked. The thermal runaway trigger temperature is increased from 200°C of traditional high-nickel ternary cathode materials to more than 260°C. The thermal runaway heat generation rate is reduced by 70%, and the “oxygen evolution-exothermic” chain reaction is completely blocked, which greatly improves the battery safety.

[0019] 3. The material of this invention exhibits excellent electrochemical performance: good in-situ doping uniformity without sacrificing material specific capacity (initial discharge specific capacity ≥ 210 mAh / g); the thermal response interface layer maintains high ion conductivity (10 mAh / g) at low temperatures. -5 S / cm), ensure Li + Rapid transmission, with a capacity retention rate of ≥90% after 200 cycles at 1C and ≥88% at 5C (compared to <80% for traditional coating materials), achieving a synergistic improvement in "high safety, high energy, and long cycle life".

[0020] 4. The material structure of the present invention has strong stability: the interface layer and the active core are tightly bonded together by synchronous construction and chemical bonding, with a peeling force ≥1.5N / cm and no shedding during cycling; due to in-situ heterovalent doping, the active core has a more stable lattice structure, and the particle cracking rate is <4% after 200 cycles (compared to >35% for traditional materials), which significantly improves the service life of the material. Detailed Implementation

[0021] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0022] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0023] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0024] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0025] The material used in this invention is "Sr" 2+ -Mo 6+ The core-shell integrated structure of "in-situ doped high-nickel active core @Li2SiO3-PEGDE (polyethylene glycol diglycidyl ether) thermally responsive self-sealing interface layer" eliminates the need for any modification to the high-nickel precursor, directly utilizing commercially available high-nickel precursors. Through the synergistic effect of "sintered in-situ doping to strengthen the core structure + thermally responsive intelligent interface layer", lattice oxygen precipitation is suppressed at the source, while simultaneously achieving dynamic switching between "conduction-protection" at high and low temperatures. The specific design is as follows: In this invention, Sr 2+ -Mo 6+ In-situ doped high-nickel active core, the general chemical formula of which is LiNi 0.90 Co 0.05 Mn 0.05 O2, directly from commercially available Ni 0.90 Co 0.05 Mn 0.05 Using (OH)₂ precursor as raw material, Sr²⁺ is achieved through a sintering process after being mixed with a lithium source. + (occupying Li) + site) and Mo 6+ (occupying Ni) 3+ In-situ co-doping at the site (to form "Sr") 2 + -Mo 6+ "Heterovalent ion pairs. Among them, Sr..." 2+ The ionic radius (1.18 Å) of Li is similar to that of Li + (0.76Å) High matching degree, allowing for uniform embedding and stable alignment of Li layers during sintering, suppressing Li + / Ni 2+ Mixing (mixing degree reduced to <2%). Due to Mo 6+ Its electronegativity (2.16) is higher than that of Ni. 3+ (1.91), during high-temperature sintering with Ni 3+ Site substitution occurs, with O 2-It forms stronger Mo-O covalent bonds (bond energy 502 kJ / mol, much higher than Ni-O bond energy 391 kJ / mol), and at the same time enhances the stability of the lattice oxygen framework through charge compensation effect, suppressing lattice oxygen precipitation at high temperature from the source, and raising the thermal runaway trigger temperature to above 260℃.

[0026] In this invention, a thermally responsive self-sealing interface layer (shell) of Li2SiO3-PEGDE is constructed in situ on the surface of the active core, forming a uniform composite interface layer with a thickness of 8-12 nm. This layer is composed of a Li2SiO3 precursor (a hydrolyzed product of tetraethyl orthosilicate) and PEGDE at a mass ratio of 2.5-3.5:2. At low temperatures (<180°C, the normal operating temperature of the battery), the PEGDE chains expand, forming a porous structure. The Li2SiO3 precursor provides Li... + Transport sites, with an interfacial layer ionic conductivity of 10. -5 S / cm, does not hinder Li + Diffusion; Under high temperature (≥180℃, thermal runaway warning temperature), PEGDE segments rapidly crosslink and solidify, while the Li2SiO3 precursor crystallizes in situ to form a dense Li2SiO3 ceramic layer (porosity <5%), which can not only immediately seal the microcracks on the surface of the active core, but also physically isolate the contact between active oxygen and electrolyte, blocking the "oxygen evolution-exothermic" chain reaction; In addition, the interface layer is bonded to the Ni atoms on the surface of the active core through Si-O-Ni chemical bonds, with strong bonding force (peeling force ≥1.5N / cm), and will not fall off or fail during cycling.

[0027] Example 1: Ni 0.90 Co 0.05 Mn 0.05 Preparation of (OH)2 precursor + Li2SiO3-PEGDE interface layer Step 1: Preparation of composite slurry: Weigh the precursor, Li2CO3, and dopant according to the molar ratio of Li / (Ni+Co+Mn+Sr+Mo)=1.04, and weigh commercially available Ni. 0.90 Co 0.05 Mn 0.05 (OH)₂ precursor (particle size 2.5 μm, purity 99.7%), Li₂CO₃ (purity 99.9%), Sr(NO₃)₂ (corresponding to Sr²⁺) + Doping amount 0.5 at%), (NH4)6Mo7O 24 4H2O (corresponding to Mo) 6+With a doping amount of 0.17 at%, satisfying x≈3y), NMP was added to adjust the solid content to 50 wt%, and ball milling (310 r / min, 2.2 h, ball-to-material ratio 3.2:1) was performed to obtain an active core slurry; TEOS, PEGDE (number average molecular weight 500), and anhydrous ethanol were mixed at a mass ratio of 3.2:2:48, and the pH was adjusted to 3.5 with 1 mol / L hydrochloric acid. The mixture was stirred at 60℃ for 2 h to obtain an interface layer slurry; the two slurries were mixed, stirred at 200 r / min for 1 h, and then sonicated at 80 kHz for 30 min to obtain a uniform core-shell composite slurry.

[0028] NMP was added to adjust the solid content to 50 wt%, and the mixture was ball-milled (310 r / min, 2.2 h, ball-to-material ratio 3.2:1) to obtain the active core slurry.

[0029] Step 2: Mix TEOS, PEGDE and anhydrous ethanol, adjust the pH to 3.5, and stir at 60℃ for 2 hours to obtain the interface layer slurry; mix the two slurries, stir at 200 r / min for 1 hour, and sonicate at 80 kHz for 30 minutes to obtain a uniform core-shell composite slurry.

[0030] Step 3: Spray drying granulation: The composite slurry is fed into a centrifugal spray dryer, with the inlet temperature set at 205℃, the outlet temperature at 92℃, and the feed rate at 48mL / h, to collect spherical particles with a diameter of 5~8μm.

[0031] Step 4: Segmented sintering: Place the particles into an alumina crucible, put it in a tube furnace, and heat it to 355℃ at 5℃ / min under an air atmosphere, hold it for 4.2h (pre-sintering to remove impurities); continue heating to 910℃, switch to an oxygen atmosphere (flow rate 210mL / min), hold it for 10.5h (in-situ doping and active nucleus formation); cool naturally to 205℃, hold it for 2.2h (interface layer solidification); after cooling to room temperature, grind it through a 300-mesh sieve to obtain the target material.

[0032] Example 2: Ni 0.85 Co 0.07 Mn 0.08 Preparation of (OH)2 precursor + Li2SiO3-PEGDE interface layer Step 1: Preparation of composite slurry: Weigh the precursor, Li2CO3, and dopant according to the molar ratio of Li / (Ni+Co+Mn+Sr+Mo)=1.03, and weigh commercially available Ni. 0.85 Co 0.07 Mn 0.08 (OH)₂ precursor (particle size 2.5 μm, purity 99.7%), Li₂CO₃ (purity 99.9%), Sr(NO₃)₂ (corresponding to Sr²⁺) + Doping amount 0.4 at%), (NH4)6Mo7O 24 4H2O (corresponding to Mo) 6+ Doping amount 0.13 at%, meets Sr 2+ Mo 6+ The mixture was prepared by ball milling (approximately 3:1), adding NMP to adjust the solid content to 50wt%, and ball milling (310r / min, 2.2h, ball-to-material ratio 3.2:1) to obtain an active core slurry. Separately, TEOS, PEGDE (number average molecular weight 500), and anhydrous ethanol were mixed at a mass ratio of 3.2:2:48, and the pH was adjusted to 3.5 with 1mol / L hydrochloric acid. The mixture was stirred at 60℃ for 2h to obtain an interface layer slurry. The two slurries were then mixed, stirred at 200r / min for 1h, and sonicated at 80kHz for 30min to obtain a uniform core-shell composite slurry.

[0033] NMP was added to adjust the solid content to 45wt%, and the mixture was ball-milled (310r / min, 2.2h, ball-to-material ratio 3.2:1) to obtain the active core slurry.

[0034] Step 2: Mix TEOS, PEGDE and anhydrous ethanol, adjust the pH to 3.5, and stir at 60℃ for 2 hours to obtain the interface layer slurry; mix the two slurries, stir at 200 r / min for 1 hour, and sonicate at 80 kHz for 30 minutes to obtain a uniform core-shell composite slurry.

[0035] Step 3: Spray drying granulation: The composite slurry is fed into a centrifugal spray dryer, with the inlet temperature set at 205℃, the outlet temperature at 92℃, and the feed rate at 48mL / h, to collect spherical particles with a diameter of 5~8μm.

[0036] Step 4: Segmented sintering: Place the particles into an alumina crucible, put it in a tube furnace, and heat it to 340℃ at 4℃ / min under an air atmosphere, hold it for 3.5h (pre-sintering to remove impurities); continue heating to 880℃, switch to an oxygen atmosphere (flow rate 210mL / min), hold it for 9h (in-situ doping and active nucleus formation); cool it naturally to 190℃, hold it for 1.5h (interface layer solidification); after cooling to room temperature, grind it through a 300-mesh sieve to obtain the target material.

[0037] Example 3: Ni 0.90 Co 0.05 Mn 0.05 Preparation of (OH)2 precursor + Li2SiO3-PEGDE interface layer Step 1: Preparation of composite slurry: Weigh the precursor, Li2CO3, and dopant according to the molar ratio of Li / (Ni+Co+Mn+Sr+Mo)=1.04, and weigh commercially available Ni. 0.90 Co 0.05 Mn 0.05(OH)₂ precursor (particle size 2.5 μm, purity 99.7%), Li₂CO₃ (purity 99.9%), Sr(NO₃)₂ (corresponding to Sr²⁺) + Doping amount 0.5 at%), (NH4)6Mo7O 24 4H2O (corresponding to Mo) 6+ With a doping amount of 0.17 at%, satisfying x≈3y), NMP was added to adjust the solid content to 50 wt%, and ball milling (310 r / min, 2.2 h, ball-to-material ratio 3.2:1) was performed to obtain an active core slurry; TEOS, PEGDE (number average molecular weight 500), and anhydrous ethanol were mixed at a mass ratio of 3.2:2:48, and the pH was adjusted to 3.5 with 1 mol / L hydrochloric acid. The mixture was stirred at 60℃ for 2 h to obtain an interface layer slurry; the two slurries were mixed, stirred at 200 r / min for 1 h, and then sonicated at 80 kHz for 30 min to obtain a uniform core-shell composite slurry.

[0038] NMP was added to adjust the solid content to 55 wt%, and the mixture was ball-milled (310 r / min, 2.2 h, ball-to-material ratio 3.2:1) to obtain the active core slurry.

[0039] Step 2: Mix TEOS, PEGDE and anhydrous ethanol, adjust the pH to 3.5, and stir at 60℃ for 2 hours to obtain the interface layer slurry; mix the two slurries, stir at 200 r / min for 1 hour, and sonicate at 80 kHz for 30 minutes to obtain a uniform core-shell composite slurry.

[0040] Step 3: Spray drying granulation: The composite slurry is fed into a centrifugal spray dryer, with the inlet temperature set at 205℃, the outlet temperature at 92℃, and the feed rate at 48mL / h, to collect spherical particles with a diameter of 5~8μm.

[0041] Step 4: Segmented sintering: Place the particles into an alumina crucible, put it in a tube furnace, and heat it to 360°C at 6°C / min under an air atmosphere, and hold it for 4.5h (pre-sintering to remove impurities); continue heating to 920°C, switch to an oxygen atmosphere (flow rate 210mL / min), and hold it for 11h (in-situ doping and active nucleus formation); cool naturally to 210°C and hold it for 2.5h (interface layer solidification); after cooling to room temperature, grind it through a 300-mesh sieve to obtain the target material.

[0042] Comparative Example 1: Ni 0.90 Co 0.05 Mn 0.05 (OH)2 precursor + undoped + Li2SiO3-PEGDE interface layer Preparation method: The preparation method is the same as in Example 1, except that Sr(NO3)2 and (NH4)6Mo7O are not added. 24 4H2O.

[0043] Comparative Example 2: Using conventional Ni 0.90 Co 0.05 Mn 0.05 (OH)2 precursor Preparation method: The conventional solid-state sintering process is used, and no additional preparation is required.

[0044] Experimental example: The following methods were used to test the indicators: The positive electrode sheets prepared in Examples 1, 2, 3 and Comparative Examples 1, 2 were punched into 12 mm diameter discs as positive electrodes, and lithium metal sheets were used as negative electrodes. They were then assembled into CR2032 coin cells in an argon-protected glove box.

[0045] At 25°C, the battery is charged to 4.4V at a rate of 0.2C, and then discharged to 3V at a rate of 0.2C. This constitutes one cycle. The charge-discharge specific capacity of this cycle is the initial specific capacity, and the charge-discharge capacity ratio is the first-efficiency value. After two cycles, the battery is charged and discharged at 1C for 100 cycles. The charge-discharge capacity of the 3rd and 103rd cycles is recorded, and the retention rate is the ratio of the discharge specific capacity of the 3rd to the 103rd cycle.

[0046]

[0047] Based on the comparison of the above embodiments and comparative examples, it can be seen that the present invention achieves Sr² through a sintering process. + (occupying Li) + site) and Mo 6+ (occupying Ni) 3+ In-situ co-doping at (site) to form "Sr 2+ -Mo 6+ "Heterovalent ion pairs, through charge compensation effect, enhance the stability of the lattice oxygen framework, suppressing lattice oxygen evolution at high temperatures from the source, and raising the thermal runaway trigger temperature to above 260℃. Furthermore, the Li2SiO3-PEGDE thermally responsive self-sealing interface layer (shell) in this invention constructs a uniform composite interface layer with a thickness of 8~12nm in situ on the surface of the active core. This not only promptly seals microcracks on the surface of the active core but also physically isolates active oxygen from contact with the electrolyte, blocking the 'oxygen evolution-exothermic' chain reaction. In addition, the interface layer is bonded to Ni atoms on the surface of the active core through Si-O-Ni chemical bonds, exhibiting strong bonding force (peeling force ≥1.5N / cm), preventing detachment and failure during cycling, and significantly improving capacity retention."

[0048] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing an in-situ doped thermally responsive self-sealing high-nickel ternary cathode material, characterized in that, Includes the following steps: Step 1: Mix the raw materials containing nickel-cobalt-manganese precursor, lithium source, strontium source, molybdenum source and solvent evenly to obtain in-situ doped active nucleus paste; Step 2: Mix the raw materials containing TEOS, polymer and solvent evenly to obtain the interface layer slurry; Step 3: Pour the in-situ doped active core slurry into the interface layer slurry and mix evenly to obtain a core-shell composite slurry; Step 4: Spray granulation of the core-shell composite slurry to obtain particulate powder; Step 5: Sinter the granular powder to obtain the in-situ doped thermally responsive self-sealing high-nickel ternary cathode material.

2. The method for preparing in-situ doped thermally responsive self-sealing high-nickel ternary cathode material according to claim 1, characterized in that, The nickel-cobalt-manganese precursor has the chemical formula Ni x Co y Mn 1-x-y (OH)2; wherein 0.85≤x≤0.92, 0.04≤y≤0.08, x+y≤1; the nickel-cobalt-manganese precursor has a particle size of 2~4μm.

3. The method for preparing in-situ doped thermally responsive self-sealing high-nickel ternary cathode material according to claim 1, characterized in that, In step one, the molar ratio of lithium to nickel-cobalt-manganese precursor is 1.03~1.05:

1.

4. The method for preparing in-situ doped thermally responsive self-sealing high-nickel ternary cathode material according to claim 1, characterized in that, In step one, Sr² + The doping concentration is 0.4~0.6 at%; Mo 6+ The doping amount is 0.15~0.25 at%.

5. The method for preparing in-situ doped thermally responsive self-sealing high-nickel ternary cathode material according to claim 1, characterized in that, In step one, the solvent is at least one of NMP, DMAc, DMSO, and DMF, and the solid content of the in-situ doped active nucleus slurry is 45-55 wt%.

6. The method for preparing in-situ doped thermally responsive self-sealing high-nickel ternary cathode material according to claim 1, characterized in that, In step two, the solvent is at least one of ethanol, methanol, and isopropanol; the mass ratio of TEOS:polymer:solvent in step two is 2.5~3.5:2:45~55. The polymer is at least one of PEGDE, PVP, PVA, and PAA; Preferably, the pH of the interface layer slurry is 3.0 to 4.

0.

7. The method for preparing in-situ doped thermally responsive self-sealing high-nickel ternary cathode material according to claim 1, characterized in that, The particle size of the powder is 5~8μm.

8. The method for preparing in-situ doped thermally responsive self-sealing high-nickel ternary cathode material according to claim 1, characterized in that, The sintering process includes: heating to 340-360°C at a rate of 4-6°C / min in an air atmosphere and holding for 3.5-4.5 hours; continuing to heat to 880-920°C at a rate of 4-6°C / min and holding for 9-11 hours in an oxygen atmosphere; then cooling to 190-210°C and holding for 1.5-2.5 hours, followed by natural cooling.

9. The in-situ doped thermally responsive self-sealing high-nickel ternary cathode material obtained by the preparation method according to any one of claims 1 to 8.

10. The application of the in-situ doped thermally responsive self-sealing high-nickel ternary cathode material as described in claim 9 in lithium batteries.

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