Uniformly-coated lithium ion battery ternary single-crystal positive electrode material and preparation method and application thereof

Abstract

The invention discloses a uniformly-coated lithium ion battery ternary single-crystal positive electrode material and a preparation method and application thereof. The preparation method comprises the following steps: mixing a ternary single crystal material precursor with a lithium source, and carrying out primary sintering and crushing treatment to prepare a ternary single crystal material; adding the ternary single crystal material into an air injection coating device, injecting compressed air to enable the ternary single crystal material to be in a boiling state, and then spraying a coating agent solution into the air injection coating device to carry out coating treatment on the ternary single crystal material; and carrying out secondary sintering and sieving iron removal treatment on the material obtained by the coating treatment to prepare the uniformly coated ternary single-crystal positive electrode material of the lithium ion battery. The positive electrode material prepared by the invention can effectively prevent direct contact between the positive electrode material and an electrolyte, reduce side reaction between the positive electrode material and the electrolyte and improve the stability of a layered result, so that the cycle life of the battery is prolonged, and the rate capability, the charge-discharge efficiency and the energy density of the battery are improved.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery cathode material technology, specifically relating to a uniformly coated ternary single-crystal cathode material for lithium-ion batteries, its preparation method, and its application. Background Technology

[0002] In April 2025, the new mandatory national standard GB 38031-2025, "Safety Requirements for Power Batteries for Electric Vehicles," requires power batteries to not catch fire or explode under various testing environments. This means that from the development of safer positive and negative electrode materials, more heat-resistant electrolytes, and special separators at the core material level, to the optimization of intelligent thermal management algorithms at the system integration level, a new round of technological upgrades will be ushered in. The future development of the power battery industry will place greater emphasis on the core principle of "safety first," driving the entire industry towards a new stage of high-quality development.

[0003] For ternary cathode materials of lithium-ion batteries, high-temperature thermal stability has always been a key research focus for researchers. In particular, for new energy electric vehicles that pursue ultra-long driving range, it is especially urgent to produce lithium-ion battery cathode materials with high energy density and high safety.

[0004] Currently, coating is one of the most common methods in the production process of ternary cathode materials, effectively improving the corrosion of cathode materials by electrolytes and preventing or slowing down side reactions between cathode materials and electrolytes. However, in most current ternary material production lines, the coating agent and the cathode material to be coated are mixed using mechanical mixing equipment under specific mixing speed and time requirements. This cannot guarantee the uniformity of the mixing between the coating agent and the cathode material, meaning that the final material is largely unevenly coated. Even with secondary sintering, the final material may still appear as an "island coating" under scanning electron microscopy, where some particles show the coating on their surface while others show no difference before and after coating. Summary of the Invention

[0005] The main objective of this invention is to provide a uniformly coated ternary single-crystal cathode material for lithium-ion batteries, its preparation method, and its application, so as to overcome the shortcomings of the prior art.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: This invention provides a method for preparing a uniformly coated ternary single-crystal cathode material for lithium-ion batteries, comprising: Ternary single crystal material is prepared by mixing a ternary single crystal material precursor with a lithium source and then performing a sintering and crushing process. The ternary single crystal material is added to the jet coating device, and compressed air is injected to make the ternary single crystal material "boiling". Then, the coating agent solution is sprayed into the jet coating device to coat the ternary single crystal material. The temperature inside the jet coating device is kept higher than the boiling point of the solute in the coating agent solution. Furthermore, the material obtained from the coating process is subjected to secondary sintering and iron removal by sieving to obtain a uniformly coated ternary single-crystal cathode material for lithium-ion batteries.

[0007] This invention also provides a uniformly coated ternary single-crystal cathode material for lithium-ion batteries prepared by the aforementioned method, comprising: a ternary single-crystal cathode material and a coating layer, wherein the coating layer is formed by a coating agent, and the chemical formula of the ternary single-crystal cathode material is Li. a Ni b Co c Mn d X e O2, where 1≤a≤1.05, 0.3≤b≤0.8, 0.02≤c≤0.35, 0.02≤d≤0.35, 0≤e≤0.06%, and X is selected from any one or more combinations of Zn, Ca, Zr, Mg, B, Ti, Nb, Ti, V, W, Sr, Si, Y, Mo, and Al.

[0008] This invention also provides the application of the aforementioned uniformly coated ternary single-crystal cathode material for lithium-ion batteries in the preparation of lithium-ion batteries.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Uniform coating: Currently, the production process of ternary single crystal cathode material for lithium-ion batteries is generally to perform simple mechanical mixing of the first-burned material and the coating agent and then perform a second-burning coating. This coating process cannot achieve uniform coating of the ternary material by the coating agent, and is a kind of "island coating". The present invention proposes to use a jet coating machine to replace the mechanical mixing coating process, which can achieve uniform coating of ternary material. (2) Improve the thermal stability of materials: The thermal failure temperature of the single-crystal ternary finished product after delithiation under the uniform coating process proposed in this invention is about 20-30℃ higher than that of the sample after delithiation under the traditional mechanical mixing coating process, and less heat is released. (3) Improve battery safety performance: The higher the thermal runaway temperature of the positive electrode material, the better the safety of the battery assembled from it; (4) Reduce production costs: After the single crystal cathode material has been uniformly coated inside the jet coating machine, it can be sintered again in the kiln, which can reduce the sintering time and reduce costs and increase efficiency. (5) Unlike spray drying, the ternary material coated by air spray does not need to be mixed with water or organic solvents. The coating agent only needs to be dissolved in the solvent and then evaporated at high temperature to adhere to the material surface. Spray drying requires both the coating agent and the coated material to be placed in an aqueous solution or organic solution for spray drying, which will result in a huge waste of water, electricity and other energy. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of this application 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 only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1a This diagram shows a typical production process flow chart for ternary single-crystal cathode materials for lithium-ion batteries. Figure 1b A process flow diagram illustrating the uniform coating proposed in this invention is shown. Figures 2a-2c The images show SEM images of single crystals coated with boric acid under different processes. NCM-A1 is the SEM image of Example 1, NCM-B1 is the SEM image of Comparative Example 1, and NCM-C1 is the SEM image of Comparative Example 4. Figures 3a-3c The images show single-crystal electron microscopy (SEM) images of alumina-coated crystals under different processes. NCM-A2 is the SEM image of Example 2, NCM-B2 is the SEM image of Comparative Example 2, and NCM-C2 is the SEM image of Comparative Example 5. Figures 4a-4c The images show single-crystal SEM images of LATP (lithium aluminum titanium phosphate) coated with different processes. NCM-A3 is the SEM image of Example 3, NCM-B3 is the SEM image of Comparative Example 3, and NCM-B3 is the SEM image of Comparative Example 6. Figure 5 The DSC curves of alumina-coated battery electrodes under different processes are shown. Figure 6 A schematic diagram of a jet coating machine according to a typical embodiment of the present invention is shown.

[0012] Reference numerals in the attached diagram: 1. Material reaction chamber; 2. Injection nozzle; 3. Compressed air pipeline; 4. Feed port; 5. Dust collection and filtration device; 6. Material receiving port; 7. Heat transfer oil jacket. Detailed Implementation

[0013] In view of the deficiencies of the prior art, the inventors of this case, through long-term research and extensive practice, have proposed the technical solution of this invention. The technical solution of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0014] Specifically, as one aspect of the technical solution of this invention, the method for preparing a uniformly coated ternary single-crystal cathode material for lithium-ion batteries includes: Ternary single crystal material is prepared by mixing a ternary single crystal material precursor with a lithium source and then performing a sintering and crushing process. The ternary single crystal material is added to the jet coating device, and compressed air is injected to make the ternary single crystal material "boiling". Then, the coating agent solution is sprayed into the jet coating device to coat the ternary single crystal material. The temperature inside the jet coating device is kept higher than the boiling point of the solute in the coating agent solution. Furthermore, the material obtained from the coating process is subjected to secondary sintering and iron removal by sieving to obtain a uniformly coated ternary single-crystal cathode material for lithium-ion batteries.

[0015] In some preferred embodiments, the preparation method specifically includes: (1) The ternary single crystal material precursor and the lithium source are mixed using a mechanical mixing device to obtain a mixture; wherein the mixing time is ≥10min, the ambient temperature is ≤25℃, and the humidity is ≤25RH% (2) The mixture is sintered once in an oxygen atmosphere to obtain a sintered material; (3) The primary sintering material is coarsely crushed and then placed in an airflow pulverizer for crushing, grading, and cyclone separation to obtain ternary single crystal material; (4) Mix the coating agent with the solvent to form a coating agent solution; add the ternary single crystal material to the jet coating device and inject compressed air to make the ternary single crystal material "boiling"; then spray the coating agent solution into the jet coating device through the nozzle so that the coating agent adheres to the surface of the ternary single crystal material to obtain the coated material. (5) The coating material is sintered in an oxygen atmosphere to obtain a secondary sintered material; (6) The secondary sintering material is fed into a batch mixing device for batch mixing to obtain batch mixed material; wherein, the ambient temperature of the batch mixing process is ≤25℃, the humidity is ≤25RH%, the frequency of the main shaft motor of the batch mixing device is ≥10Hz, and the batch mixing time is ≥10min. (7) The batch mixed material is sieved and iron removed to obtain sieved iron removed material; wherein, the ambient temperature of sieving is ≤25℃, the humidity is ≤25RH%, the mesh size of the sieve is <400 mesh, and the magnetic field strength used for iron removal is ≥1000Gs. (8) The sieved iron-removed material is packaged using a vacuum packaging device to obtain a uniformly coated ternary single crystal cathode material for lithium-ion batteries; wherein the ambient temperature of the packaging process is ≤25℃ and the humidity is ≤25RH.

[0016] In some preferred embodiments, the molar ratio of the lithium source to the ternary single crystal precursor is a, where 1 ≤ a ≤ 1.04.

[0017] In some preferred embodiments, the ternary single-crystal material precursor includes Ni. 0.83 Co 0.12 Mn 0.05 (OH)2 and / or Ni 0.6 Co 0.1 Mn 0.3 (OH)2, and not limited to this.

[0018] In some preferred embodiments, the lithium source includes LiOH·H2O and / or Li2CO3, but is not limited thereto.

[0019] In some preferred embodiments, step (1) further includes mixing the ternary single crystal material precursor, the lithium source, and the dopant containing element X using a mechanical mixing device.

[0020] Furthermore, the molar ratio of the dopant containing element X to the ternary single crystal precursor is e:1, where 0≤e≤0.06%.

[0021] Furthermore, the dopant containing element X includes any one or more combinations of oxides, hydroxides, carbonates, and basic carbonates containing element X, and is not limited thereto.

[0022] Furthermore, the X element in the X-containing dopant includes any one or more combinations of Zn, Ca, Zr, Mg, B, Ti, Nb, Ti, V, W, Sr, Si, Y, Mo, and Al, and is not limited thereto.

[0023] In some preferred embodiments, the temperature of the first sintering is ≥650°C, the sintering time is ≥10h, and the oxygen concentration of the oxygen atmosphere is ≥90%.

[0024] In some preferred embodiments, the particle size D of the ternary single crystal material 10 It is 1.5±0.5μm, D 50 It is 3.5±0.5μm, D 90It is 5.5 ± 0.5 μm.

[0025] In some preferred embodiments, the coating agent includes oxides, hydroxides, or solid electrolytes.

[0026] Furthermore, the oxide includes any one or more combinations of aluminum oxide, boric acid, boron oxide, aluminum oxide, titanium oxide, and tungsten oxide, and is not limited thereto.

[0027] Furthermore, the hydroxide includes any one or more combinations of cobalt hydroxide, aluminum hydroxide, magnesium hydroxide, and manganese hydroxide, and is not limited thereto.

[0028] Furthermore, the solid electrolyte includes any one or more combinations of LATP, LLZO, and LPSC, but is not limited thereto.

[0029] In some preferred embodiments, the solvent is a non-flammable inorganic or organic solvent.

[0030] Furthermore, the solvent includes any one or more combinations of water, polyethylene glycol, polypropylene glycol, and N-methylpyrrolidone, and is not limited thereto.

[0031] In some preferred embodiments, the jet coating device (such as...) Figure 6 As shown, it includes a material reaction chamber 1, an injection nozzle 2, a compressed air pipeline 3, a feeding port 4, a dust collection and filtration device 5, a receiving port 6, and a heat transfer oil jacket 7; the injection nozzle is located below the material reaction chamber, the compressed air pipeline is connected to the injection nozzle, the receiving port is located below the material reaction chamber, the heat transfer oil jacket is located around the material reaction chamber, and the feeding port and dust collection and filtration device are located above the material reaction chamber.

[0032] In some preferred embodiments, the secondary sintering temperature is ≥200°C, the sintering time is ≥5h, and the oxygen concentration in the oxygen atmosphere is ≥85%.

[0033] Specifically, the preparation method of the uniformly coated ternary single-crystal cathode material for lithium-ion batteries in this invention includes the following steps: Dry mixing of materials. The NCM ternary precursor and lithium source are weighed according to the stoichiometric ratio a=Li / M (1≤a≤1.04), and mixed using a mechanical mixer; First sintering. The uniformly mixed material is weighed, evenly distributed into saggers, leveled and cut into pieces, stacked, and then sequentially fed into a furnace for calcination; Crushing. After the first calcination, the material is removed from the saggers, first coarsely crushed using a crushing device, and then crushed, graded, and separated using an air jet mill to obtain ternary single-crystal material with qualified particle size; Coating. The crushed single-crystal material is fed into an air jet coating machine. Compressed air is introduced into the machine through a compressed air pipeline, causing the material inside to flow rapidly, reaching a "boiling" state. Then, the coating agent is dissolved in a solvent, and the solvent-containing coating agent solution or suspension is sprayed into the machine through a nozzle. The jacket of the jet coating machine is made of high-temperature heat-conducting oil. The solvent evaporates immediately upon contact with the high-temperature environment, and the coating agent instantly adheres to the surface of the single crystal material, achieving a uniform coating effect; Secondary sintering. To form a relatively strong coating layer on the surface of the single crystal material, the uniformly mixed materials are placed in a secondary firing kiln for secondary sintering. The mixed materials are weighed and evenly distributed into saggers. After the materials in the saggers are leveled and cut into pieces, they are stacked and then sequentially fed into the furnace for secondary firing; Batch mixing. The ternary single crystal material obtained from the secondary sintering is conveyed to the batch mixing process under positive or negative pressure, where it is batch mixed according to the process requirements; Sieving and iron removal. The batch-mixed material is sieved in a vibrating screen, and then passes through an electromagnetic iron remover for iron removal; Packaging. After sieving and iron removal, the material is sealed in a vacuum packaging machine.

[0034] In some more specific embodiments, the preparation method of the uniformly coated ternary single-crystal cathode material for lithium-ion batteries includes the following steps (as shown in Table 1): (1) Dry mixing of ingredients: Weigh the NCM ternary precursor and lithium source according to the metering ratio a=Li / M (1≤a≤1.04) and mix them using a mechanical mixer. The mechanical mixing time shall not be less than 10 min, and the ambient temperature of the mixing environment shall not exceed 25℃ and the humidity shall not exceed 25RH.

[0035] (2) Primary sintering: The material after mechanical mixing in step (1) is weighed and evenly distributed into saggers of 330mm*330mm*120mm. The material in the saggers is leveled and cut into pieces, then stacked on top of each other and placed into the furnace for calcination. The filling weight of the corundum saggers ranges from 2kg to 7kg. The sintering atmosphere in the kiln is oxygen, with an oxygen concentration of not less than 90%. The sintering cycle is not less than 10 hours, and the sintering temperature is not less than 650℃.

[0036] (3) Crushing: After the first roasting is completed, the material in the sagger is taken out and put into the crushing equipment for coarse crushing. Then, the air jet mill is used for crushing, grading, cyclone separation and other processes to obtain ternary single crystal material with qualified particle size.

[0037] (4) Coating: The crushed single crystal material is fed into a jet coating machine (structure as shown in the figure). Figure 6 Inside the machine, compressed air is introduced into the equipment through a compressed air pipeline, causing the material inside to flow rapidly and reach a "boiling" state. The coating agent is then dissolved in a solvent, and the solvent-containing coating agent solution or suspension is sprayed into the equipment through nozzles. The jacket of the jet coating machine is made of high-temperature heat-conducting oil. The solvent evaporates immediately upon contact with the high-temperature environment, and the coating agent instantly adheres to the surface of the single-crystal material, achieving a uniform coating effect.

[0038] (5) Secondary sintering: In order to form a relatively solid coating layer on the surface of the single crystal material, the uniformly coated material from step (4) is placed in a secondary sintering kiln for secondary sintering. By weighing, the mixed material is evenly distributed into saggers of 330mm*330mm*120mm size. After the material in the saggers is leveled and cut into pieces, the saggers are stacked one on top of the other and then placed into the kiln for firing. The sagger loading range for corundum is 4kg~10kg. The sintering atmosphere in the kiln is oxygen, the oxygen concentration in the kiln is not less than 85%, the sintering cycle is not less than 5h, and the sintering temperature is not less than 200℃.

[0039] (6) Batch mixing: The ternary single crystal material obtained by secondary sintering is conveyed to the batch mixing process by positive or negative pressure conveying, and the batch mixing is completed in the batch mixer according to the process requirements. The ambient temperature of the batch mixing workshop shall not exceed 25℃ and the humidity shall not exceed 20%RH%. The frequency of the main shaft motor of the batch mixer shall not be lower than 10Hz and the batch mixing time shall not be less than 10min.

[0040] (7) Screening and iron removal: After batch mixing, the material is screened in the vibrating screen room, and then iron is removed by an electromagnetic iron remover. The ambient temperature of the screening room shall not exceed 25℃ and the humidity shall not exceed 20%RH%. The screen used shall not be less than 400 mesh. After the electromagnetic iron remover is powered on, its magnetic field strength shall not be less than 1000Gs.

[0041] (8) Packaging: After iron removal by sieving, the material is sealed by a vacuum packaging machine. The ambient temperature in the packaging room shall not exceed 25℃ and the humidity shall not exceed 20%RH.

[0042] As a preferred option, the process of dry mixing of materials in step (1) of the above production process also includes the step of adding a dopant. The dopant is added according to the molar ratio of element X to ternary single crystal material NCM e:1. Element X is selected from its oxides, hydroxides or carbonates or basic carbonates containing element X, etc., where 0≤e≤0.06%; the element X is at least one element selected from Zn, Ca, Zr, Mg, B, Ti, Nb, Ti, V, W, Sr, Si, Y, Mo and Al. In the secondary mixing process in step (4), the coating agent used is one or more of the oxides, hydroxides or solid electrolytes such as alumina, boric acid, boron oxide, alumina, titanium oxide, tungsten oxide, cobalt hydroxide, LATP, LLZO, LPSC, etc.

[0043] Preferably, the solvent used in the uniform coating process is a non-flammable inorganic or organic solvent such as water, polyethylene glycol, polypropylene glycol, or N-methylpyrrolidone.

[0044] Preferably, the lithium source used in the dry mixing process of step (1) is either LiOH·H2O or Li2CO3; the mechanical mixing equipment in steps (1) and (4) is either a plow mixer or a high-speed mixer. The mixer speed r is in the range of 200rpm / min≤r≤2000rpm / min.

[0045] Preferably, the primary sintering in step (2) uses a roller kiln with a length of 20m to 60m. The kiln is divided into a heating zone, a constant temperature zone, and a cooling zone. The kiln head is equipped with an exhaust fan, the kiln tail is equipped with a cold zone fan and cooling circulating water, and the kiln top is equipped with exhaust and air supply baffles. The secondary sintering in step (5) uses either a roller kiln or a rotary kiln. The kiln is also divided into a heating zone, a constant temperature zone, and a cooling zone.

[0046] Preferably, the coarse crushing equipment in step (3) is one or more of the following: a rotary mill, a colloid mill, a jaw crusher-roller mill, etc. The classifying frequency of the airflow mill in step (3) is not less than 10Hz, and the induced draft frequency is not less than 15Hz. After airflow milling, the particle size D of the ternary single crystal material is determined. 10 =1.5±0.5μm, D 50 =3.5±0.5μm, D 90 =5.5±0.5μm.

[0047] Another aspect of this invention provides a uniformly coated ternary single-crystal cathode material for lithium-ion batteries prepared by the aforementioned method, comprising: a ternary single-crystal cathode material and a coating layer, wherein the coating layer is formed by a coating agent, and the chemical formula of the ternary single-crystal cathode material is Li. a Ni b Co c Mn d Xe O2, where 1≤a≤1.05, 0.3≤b≤0.8, 0.02≤c≤0.35, 0.02≤d≤0.35, 0≤e≤0.06%, and X is selected from any one or more combinations of Zn, Ca, Zr, Mg, B, Ti, Nb, Ti, V, W, Sr, Si, Y, Mo, and Al.

[0048] In some preferred embodiments, 0.55≤b≤0.65; 0.1≤c≤0.25; 0.15≤d≤0.35.

[0049] In some preferred embodiments, the uniformly coated ternary single-crystal cathode material for lithium-ion batteries has a particle size D50 of 3.4 ± 1 μm and a specific surface area BET of 0.5 ± 0.2 m². 2 / g.

[0050] In some preferred embodiments, the uniformly coated ternary single-crystal cathode material for lithium-ion batteries has a first discharge specific capacity of ≥190mAh / g at 0.1C within a voltage range of 2.8~4.5V, and a capacity retention rate of ≥90% after 50 cycles at 1C.

[0051] Another aspect of the present invention provides the application of the aforementioned uniformly coated ternary single-crystal cathode material for lithium-ion batteries in the preparation of lithium-ion batteries.

[0052] This invention proposes a production process for uniformly coated ternary single-crystal cathode materials for lithium-ion batteries. It proposes using a jet coating machine to replace traditional high-speed mixers or plow mixers, allowing the coating agent to be uniformly coated with the cathode material before secondary sintering, rather than the simple mechanical mixing of traditional processes. The cathode material prepared by this process will have a stable amorphous layer on its surface. This amorphous layer acts as a physical barrier, effectively preventing direct contact between the cathode material and the electrolyte, reducing side reactions between the cathode material and the electrolyte, improving the stability of the layered structure, thereby extending the battery's cycle life and improving rate performance. The uniformly coated amorphous layer can also improve the electronic and ionic conductivity of the cathode material, optimize the charge transfer process, reduce resistance, and improve the battery's charge and discharge efficiency, thus increasing the battery's energy density. When such a cathode material is applied to a battery, it will reduce gas production during charge and discharge, thereby improving battery safety, reducing the risk of thermal runaway, and maximizing the preventability of the power battery from catching fire or exploding.

[0053] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0054] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0055] In the following embodiments, the ternary single crystal precursor used must meet the following criteria: (1) The scanning electron microscope morphology shows well-distributed intermittent particles with good whisker growth; (2) TD≥1.2g / cm 3 ; (3) Span (D90-D10 / D50)=0.7±0.1, D50=3.2±0.2μm; (4) BET=15±2m 2 / g.

[0056] Example 1 Example 1 provides a production process for a ternary single-crystal cathode material for lithium-ion batteries that can achieve uniform boric acid coating. The specific process flow diagram is attached. Figure 1b The specific implementation plan is as follows: Step 1: Dry mixing of ingredients. Mix battery-grade lithium carbonate and ternary single-crystal material precursor Ni... 0.6 Co 0.1 Mn 0.3 (OH)₂ was metered at a molar ratio of 1.04:1 and then fed into a high-speed mixer. A 2000L high-speed mixer was used for this batching. The weight of lithium carbonate was 210.044 kg, and the weight of the ternary single-crystal precursor was 500 kg. Additive X was added during the feeding process according to process requirements. The mixing speed was 500-1000 rpm / min for 10-15 min, and the mixing speed was 1000-1500 rpm / min for 30-50 min. Ambient temperature and humidity were strictly controlled during the mixing process. After mixing, a primary mixture of NCM-A1 was obtained.

[0057] Step 2: Primary sintering. The mixed material is weighed and evenly distributed into 330mm*330mm*120mm saggers. After leveling and cutting, the saggers are stacked and then sequentially fed into the furnace for calcination. The upper sagger contains 4.5kg, and the lower sagger contains 3.5kg. The kiln used is a two-layer, four-row, 50-meter roller kiln. A total of 22 rows and 176 saggers were fed into the kiln. The sintering atmosphere in the kiln is oxygen, with an oxygen concentration of no less than 60% in the heating zone and no less than 80% in the high-temperature zone. The primary sintering temperature is 900-1000℃, and the sintering cycle is 24 hours. Upon completion of sintering, the primary sintered material of NCM-A1 is obtained.

[0058] Step 3: Crushing. The above-mentioned raw material is first coarsely crushed in a sagger using a rotary mill, and then further crushed, classified, and separated by an air jet mill to obtain ternary single crystal material with qualified particle size. The air jet mill's classification motor frequency is 80-120Hz (SNMA250Hz AC servo motor), the induced draft frequency is 35-50Hz, and the grinding pressure is 0.5±0.2MPa. The particle size D of the crushed material is... 10 =1.5±0.5μm, D 50 =3.3±0.3μm, D 90 =5.3±0.5μm. After crushing, 480kg of NCM-A1 crushed material was obtained.

[0059] Step 4: Coating. The crushed 100kg of single-crystal NCM-A1 material is fed into an air-jet coating machine. Compressed air enters the equipment through a compressed air pipe, rapidly releasing pressure and generating a high-speed impact force that causes the material inside the equipment to flow rapidly, reaching a "boiling" state. Then, 39.7g of boric acid coating agent is dissolved in 500ml of pure water, and the boric acid solution is sprayed into the equipment through a nozzle. The jacket of the air-jet coating machine is made of high-temperature (120-170℃) heat-conducting oil. The water evaporates immediately upon contact with the high-temperature environment, and the boric acid coating agent instantly adheres to the surface of the single-crystal material, achieving a uniform coating effect. The coating amount in this process is 500ppm. This coating process can be completed within 2-5 minutes. Through 4-5 coatings, the 480kg of material from Step 3 is uniformly coated.

[0060] Step 5: Secondary Sintering. To form a relatively robust coating layer on the surface of the single-crystal material, the ternary single-crystal material uniformly coated with boric acid was placed in a kiln for secondary sintering. The upper and lower saggers each weighed 4 kg. The kiln used was a two-layer, four-row, 50-meter roller kiln, with a total of 120 saggers in 15 rows. The sintering atmosphere in the kiln was oxygen, with an oxygen concentration of not less than 50% in the heating zone and not less than 70% in the high-temperature zone. The primary sintering temperature was 200-400℃, and the sintering cycle was 18-20 hours. After sintering, the secondary sintered NCM-A1 material was obtained.

[0061] Step 6: Batch Mixing. The ternary single-crystal materials obtained from the secondary sintering in each sagger are conveyed to the batch mixing process via positive or negative pressure conveying. Batch mixing is completed in the batch mixer according to the process requirements. The temperature and humidity of the batch mixing room must meet the process requirements. The frequency of the batch mixer spindle motor is not less than 15Hz, the batch mixing time is not less than 30 minutes, and the material temperature during batch mixing does not exceed 45℃.

[0062] Step 7: Sieving and Iron Removal. After batch mixing, the material is sieved in a vibrating screen room, and then iron is removed by an electromagnetic iron remover. The ambient temperature for sieving and iron removal should not exceed 25℃, and the humidity should not exceed 25%RH. The sieve used should have a mesh size of 350 mesh at both the top and bottom. The magnetic field strength for electromagnetic iron removal should not be less than 3500Gs.

[0063] Step 8: Packaging. After iron removal by sieving, the material is sealed using a vacuum packaging machine. The ambient temperature in the packaging room does not exceed 25℃, and the humidity does not exceed 20%RH. The final product is NCM-A1 ternary single crystal cathode material.

[0064] Example 2 Example 2 provides a production process for a lithium-ion battery ternary single-crystal cathode material capable of achieving uniform alumina coating. The specific process flow and implementation scheme are consistent with Example 1, the only difference being that the coating agent used in Step 4 is nano-alumina particles. The alumina weight corresponding to 100kg of ternary single-crystal material is 94.5g. This process achieves a coating amount of 500ppm, and through 4-5 coating cycles, the 480kg of material in Step 3 is uniformly coated. Finally, NCM-A2 ternary single-crystal cathode material is obtained.

[0065] Example 3 Example 3 provides a production process for a ternary single-crystal cathode material for lithium-ion batteries that achieves uniform solid electrolyte coating. The specific process flow and implementation scheme are consistent with Example 1, the only difference being that the coating agent used in Step 4 is nano-LATP (lithium aluminum titanium phosphate) particles. The weight of LATP corresponding to 100 kg of ternary single-crystal material is 50 g, and the coating amount in this process is 0.05 wt%. Through 4-5 coating cycles, the 480 kg of material in Step 3 is uniformly coated, ultimately yielding an NCM-A3 ternary single-crystal cathode material.

[0066] Comparative Example 1 Comparative Example 1 provides a traditional production process for ternary single-crystal cathode materials for lithium-ion batteries. The difference from Example 1 is that in Step 4, a mechanical mixer is used to simply mix the coating agent with the ternary single-crystal cathode material. After sintering in a furnace, the ternary single-crystal cathode material is obtained. The specific process flow diagram is attached. Figure 1a The specific production process is as follows: Step 1: Dry Mixing of Ingredients. Battery-grade lithium carbonate and ternary single-crystal precursor were metered at a molar ratio of 1.04:1 and then fed into a high-speed mixer. A 2000L high-speed mixer was used for this mixing process. The weight of lithium carbonate was 210.044 kg, and the weight of the ternary single-crystal precursor was 500 kg. Additive X was added during the feeding process according to process requirements. The mixing speed was low (500-1000 rpm / min) for 10-15 min, and high (1000-1500 rpm / min) for 30-50 min. The ambient temperature and humidity were strictly controlled during the mixing process. After mixing, a primary mixture of NCM-B1 was obtained.

[0067] Step 2: Primary sintering. The mixed material is weighed and evenly distributed into 330mm*330mm*120mm saggers. After leveling and cutting into pieces, the saggers are stacked and then sequentially fed into the furnace for calcination. The upper sagger contains 4.5kg, and the lower sagger contains 3.5kg. The kiln used is a two-layer, four-row, 50-meter roller kiln. A total of 22 rows and 176 saggers were fed into the kiln. The sintering atmosphere in the kiln is oxygen, with an oxygen concentration of no less than 60% in the heating zone and no less than 80% in the high-temperature zone. The primary sintering temperature is 900-1000℃, and the sintering cycle is 24 hours. The resulting NCM-B1 primary sintered material is obtained upon completion of sintering.

[0068] Step 3: Crushing. The above-mentioned raw material is first coarsely crushed in a sagger using a rotary mill, and then further crushed, classified, and separated by an air jet mill to obtain ternary single crystal material with qualified particle size. The air jet mill's classification motor frequency is 80-120Hz (SNMA250Hz AC servo motor), the induced draft frequency is 35-50Hz, and the grinding pressure is 0.5±0.2MPa. The particle size D of the crushed material is... 10 =1.5±0.5μm, D 50 =3.3±0.3μm, D 90 =5.3±0.5μm. After crushing, 480kg of NCM-B1 crushed material was obtained.

[0069] Step 4: Secondary Batching. The 480kg of crushed single-crystal NCM-B1 material was fed into a high-speed mixer. A 1000L high-speed mixer was used for this secondary batching. Then, the weighed 190.56g of boric acid was added to the high-speed mixer. Mixing was performed at a low speed of 500-1000 rpm / min for 10-15 minutes, and at a high speed of 1000-1500 rpm / min for 30-50 minutes.

[0070] Step 5: Secondary Sintering. The mixed material is placed in a kiln for secondary sintering. The upper and lower saggers are each 4 kg in weight. The kiln used is a two-layer, four-row, 50-meter roller kiln. A total of 120 saggers in 15 rows are fed into the kiln. The sintering atmosphere in the kiln is oxygen, with an oxygen concentration of not less than 50% in the heating zone and not less than 70% in the high-temperature zone. The primary sintering temperature is 200-400℃, and the sintering cycle is 18-20 hours. After sintering, the secondary sintered material of NCM-B1 is obtained.

[0071] Step 6: Batch Mixing. The ternary single-crystal materials obtained from the secondary sintering in each sagger are conveyed to the batch mixing process via positive or negative pressure conveying. Batch mixing is completed in the batch mixer according to the process requirements. The temperature and humidity of the batch mixing room must meet the process requirements. The frequency of the batch mixer spindle motor is not less than 15Hz, the batch mixing time is not less than 30 minutes, and the material temperature during batch mixing does not exceed 45℃.

[0072] Step 7: Sieving and Iron Removal. After batch mixing, the material is sieved in a vibrating screen room, and then iron is removed by an electromagnetic iron remover. The ambient temperature for sieving and iron removal should not exceed 25℃, and the humidity should not exceed 25%RH. The sieve used should have a mesh size of 350 mesh at both the top and bottom. The magnetic field strength for electromagnetic iron removal should not be less than 3500Gs.

[0073] Step 8: Packaging. After iron removal by sieving, the material is sealed using a vacuum packaging machine. The ambient temperature in the packaging room does not exceed 25℃, and the humidity does not exceed 20%RH. The final product is NCM-B1 ternary single-crystal cathode material.

[0074] Comparative Example 2 Comparative Example 2 provides a production process for lithium-ion battery ternary single-crystal cathode materials by mechanically mixing alumina and ternary single-crystal materials using a high-speed mixer or a plow mixer, followed by sintering to obtain alumina-coated ternary single-crystal cathode materials. The specific process flow and implementation scheme are consistent with Comparative Example 1, the only difference being that nano-alumina particles are used as additives in the secondary batching process of Step 4. The alumina weight corresponding to 480kg of ternary single-crystal material is 453.5g, and the coating amount in this process is 500ppm. After secondary sintering, the final NCM-B2 ternary single-crystal cathode material is obtained.

[0075] Comparative Example 3 Comparative Example 3 provides a production process for a solid electrolyte-coated ternary single-crystal cathode material for lithium-ion batteries, which involves mechanically mixing nano-solid electrolyte materials and ternary single-crystal materials using a high-speed mixer or a plow mixer, followed by sintering. The specific process flow and implementation scheme are consistent with Comparative Example 1, the only difference being that the additive used in the secondary batching process of Step 4 is nano-LATP (lithium aluminum titanium phosphate) particles. The LATP weight corresponding to 480 kg of ternary single-crystal material is 240 g, and the coating amount in this process is 0.05 wt%. After secondary sintering, the final NCM-B3 ternary single-crystal cathode material is obtained.

[0076] Comparative Example 4 Comparative Example 4 provides a production process for coating ternary single-crystal cathode materials for lithium-ion batteries using a spray dryer. The difference from Example 1 is that in Step 4, a spray dryer is used to spray-dry and mix the coating agent with the ternary single-crystal cathode material, followed by sintering in a furnace to obtain the ternary single-crystal cathode material. The difference between the spray dryer and this invention is that spray drying requires dissolving the cathode material, coating agent, and solvent together in a container, and then pumping the slurry into the spray dryer chamber for solid-liquid separation. The specific production process is as follows: Step 1: Dry Mixing of Ingredients. Battery-grade lithium carbonate and ternary single-crystal precursor were metered at a molar ratio of 1.04:1 and then fed into a high-speed mixer. A 2000L high-speed mixer was used for this mixing process. The weight of lithium carbonate was 210.044 kg, and the weight of the ternary single-crystal precursor was 500 kg. Additive X was added during the feeding process according to process requirements. The mixing speed was low (500-1000 rpm / min) for 10-15 min, and high (1000-1500 rpm / min) for 30-50 min. Ambient temperature and humidity were strictly controlled during the mixing process. After mixing, a primary mixture of NCM-C1 was obtained.

[0077] Step 2: Primary sintering. The mixed material is weighed and evenly distributed into 330mm*330mm*120mm saggers. After leveling and cutting into pieces, the saggers are stacked and then sequentially fed into the furnace for calcination. The upper sagger contains 4.5kg, and the lower sagger contains 3.5kg. The kiln used is a two-layer, four-row, 50-meter roller kiln. A total of 22 rows and 176 saggers were fed into the kiln. The sintering atmosphere in the kiln is oxygen, with an oxygen concentration of no less than 60% in the heating zone and no less than 80% in the high-temperature zone. The primary sintering temperature is 900-1000℃, and the sintering cycle is 24 hours. Upon completion of sintering, the primary sintered material of NCM-C1 is obtained.

[0078] Step 3: Crushing. The above-mentioned raw material is first coarsely crushed in a sagger using a rotary mill, and then further crushed, classified, and separated by an air jet mill to obtain ternary single crystal material with qualified particle size. The air jet mill's classification motor frequency is 80-120Hz (SNMA250Hz AC servo motor), the induced draft frequency is 35-50Hz, and the grinding pressure is 0.5±0.2MPa. The particle size D of the crushed material is... 10 =1.5±0.5μm, D 50 =3.3±0.3μm, D 90 =5.3±0.5μm. After crushing, 480kg of NCM-C1 crushed material was obtained.

[0079] Step 4: Spray Drying. The crushed 480 kg of single-crystal NCM-C1 material was fed into a 2000 L stirred tank (pre-filled with 1920 kg of pure water, with a solid content of approximately 20%). Then, 190.56 g of weighed boric acid was added to the stirred tank. The stirred tank was rotated at 500-1000 rpm / min for 10-15 min. The uniformly mixed slurry was then pumped into a spray dryer for solid-liquid separation, ultimately yielding a mixture of spray-dried cathode material and the additive boric acid.

[0080] Step 5: Secondary Sintering. The spray-dried material is placed in a kiln for secondary sintering. The upper and lower saggers are each 4 kg in weight. The kiln used is a two-layer, four-row, 50-meter roller kiln. A total of 120 saggers in 15 rows are fed into the kiln. The sintering atmosphere in the kiln is oxygen, with an oxygen concentration of no less than 50% in the heating zone and no less than 70% in the high-temperature zone. The primary sintering temperature is 200-400℃, and the sintering cycle is 18-20 hours. Upon completion of sintering, the secondary sintered material of NCM-C1 is obtained.

[0081] Step 6: Batch Mixing. The ternary single-crystal materials obtained from the secondary sintering in each sagger are conveyed to the batch mixing process via positive or negative pressure conveying. Batch mixing is completed in the batch mixer according to the process requirements. The temperature and humidity of the batch mixing room must meet the process requirements. The frequency of the batch mixer spindle motor is not less than 15Hz, the batch mixing time is not less than 30 minutes, and the material temperature during batch mixing does not exceed 45℃.

[0082] Step 7: Sieving and Iron Removal. After batch mixing, the material is sieved in a vibrating screen room, and then iron is removed by an electromagnetic iron remover. The ambient temperature for sieving and iron removal should not exceed 25℃, and the humidity should not exceed 25%RH. The sieve used should have a mesh size of 350 mesh at both the top and bottom. The magnetic field strength for electromagnetic iron removal should not be less than 3500Gs.

[0083] Step 8: Packaging. After iron removal by sieving, the material is sealed using a vacuum packaging machine. The ambient temperature in the packaging room does not exceed 25℃, and the humidity does not exceed 20%RH. The final product is a spray-dried coated and mixed NCM-C1 ternary single crystal cathode material.

[0084] Comparative Example 5 Comparative Example 5 provides a production process for lithium-ion battery ternary single-crystal cathode materials by spray drying a mixture of alumina and ternary single-crystal sintering liquid phases, followed by a second sintering. The specific process flow and implementation scheme are consistent with Comparative Example 4, the only difference being that nano-alumina particles are used as the additive in Step 4's spray drying process. The alumina weight corresponding to 480 kg of ternary single-crystal material is 453.5 g, and the coating amount in this process is 500 ppm. After the second sintering, the final NCM-C2 ternary single-crystal cathode material is obtained.

[0085] Comparative Example 6 Comparative Example 6 provides a production process for a lithium-ion battery ternary single-crystal cathode material coated with a solid electrolyte. This process involves mixing nano-solid electrolyte material and ternary single-crystal sintering liquid phase using a spray dryer, followed by spray drying and subsequent sintering. The specific process flow and implementation scheme are consistent with Comparative Example 5, the only difference being that the additive used in Step 4, the spray drying process, is nano-LATP (lithium aluminum titanium phosphate) particles. The LATP weight corresponding to 480 kg of ternary single-crystal material is 240 g, and the coating amount in this process is 0.05 wt%. After the second sintering, the final NCM-C3 ternary single-crystal cathode material is obtained.

[0086] Figures 2a-2c The scanning electron microscope (SEM) images in the image show the morphology of the ternary single-crystal material H3BO3@NCM-A1 prepared using a uniform coating process, the morphology of H3BO3@NCM-B1 prepared using a traditional mixing process, and the morphology of H3BO3@NCM-B1 prepared using a spray dryer with spray coating. Figures 2a-2c It can be seen that there is not much difference between different boron coating processes. This is because boric acid melts and flows during the secondary calcination process, forming an amorphous glassy structure on the material surface, which is difficult to capture by electron microscopy on the surface of primary particles. However, from... Figures 3a-3c and Figures 4a-4c The differences between the different coating processes are quite obvious in the electron microscope images. Figures 2a-2cThe scanning electron microscope (SEM) images shown below depict the morphologies of Al2O3@NCM-A2 prepared using a uniform coating process, Al2O3@NCM-B2 prepared using a traditional mixing process, and H3BO3@NCM-C2 prepared using a spray dryer. Unlike the high-temperature molten flow coating of boric acid, the surface of alumina in single-crystal materials can be clearly observed under an SEM. The uniform coating process produces Al2O3@NCM-A2 with a uniform coating layer, while the traditional mechanical mixing and spray drying processes produce Al2O3@NCM-A2 with uneven, "island-like" coatings. This phenomenon is further illustrated in the following sections. Figures 4a-4c This was also observed in the solid electrolyte LATP (lithium aluminum titanium phosphate) coating process of Example 3 and Comparative Example 3. Therefore, it can be seen that the coating process using a jet coating machine can achieve uniform coating of the coating agent on the surface of single-crystal materials.

[0087] In the electrochemical performance testing, the CR2032 coin cell was assembled using the following method: The positive electrode material, acetylene black, and PVDF were mixed uniformly in NMP solvent at a weight ratio of 92:4:4 using a homogenizer. The slurry was then uniformly coated onto aluminum foil and vacuum-dried at 110℃ for 12 hours before being punched into a positive electrode sheet. Lithium metal sheets and glass fiber membranes were used as the counter electrode and separator, respectively. 1.2M LiPF6 EC+EMC (volume ratio 1:1) was used as the electrolyte. The CR2032 coin cell was assembled in an argon-protected glove box (water and oxygen content ≤0.01 ppm). The slurry preparation and coating environment were strictly controlled, with an ambient dew point temperature ≤-40% and an indoor temperature of 20~25 degrees Celsius, which was kept constant. The assembled coin cells were then tested using a blue-light test cabinet. The positive electrode material voltage test range was 2.8-4.5V, and the nominal capacity was 180mAh / g. The characterization results are shown in Table 1.

[0088] Table 1 Comparing NCM-A1, NCM-B1, and NCM-C1, it can be found that although no differences were observed on the electron microscopes of the three samples, the 1C50 cycle capacity retention rate of the single crystal material uniformly coated by the jet coating machine was 99.81%, which was slightly better than the 98.06% of mechanical mixing coating and the 98.23% of spray drying coating. This is because although boric acid melts and flows at high temperatures, if the coating agent is coated and bonded to the ternary single crystal material before the secondary sintering, the overall coating will be more uniform during the sintering process, reducing the direct contact between the active material and the electrolyte over a larger area, reducing the occurrence of side reactions, and improving the cycle stability of the battery.

[0089] The 0.1C first charge of NCM-A2, NCM-B2, and NCM-C2 materials coated with alumina showed no difference under different processes, but the NCM-A2 sample coated using the jet coating machine exhibited slightly better cycle performance. To further verify that uniform coating can improve the thermal stability of the material, the R&D team disassembled the CR2032 coin cell that had completed its first charge cycle and removed the active material from the current collector for DSC testing. The test results are attached. Figure 5 DSC data shows that the thermal decomposition temperature of the single-crystal sample uniformly coated by the jet coating machine is 252.5℃, which is much higher than the thermal decomposition temperature of the conventionally mechanically mixed coated delithiated sample (235℃) and also higher than the thermal decomposition temperature of the spray-dried coated delithiated sample (245℃). Furthermore, the delithiated NCM-A2 sample exhibits less heat release in terms of heat dissipation area. This result indicates that the product produced by the uniform coating process proposed in this invention has high thermal stability, and the corresponding battery has high safety.

[0090] The NCM-A3, NCM-B3, and NCM-C3 materials coated with solid electrolyte LATP (lithium aluminum titanium phosphate) showed no difference in 0.1C first discharge under different processes. The NCM-A3 sample made by the jet coating machine also showed superior cycle performance, which provides ideas for the coating modification of ternary cathode materials for solid batteries.

[0091] In summary, the cathode material prepared by this invention forms a stable amorphous layer on its surface. This amorphous layer acts as a physical barrier, effectively preventing direct contact between the cathode material and the electrolyte, reducing side reactions between the cathode material and the electrolyte, and improving the stability of the layered structure. This, in turn, extends the battery's cycle life and improves its rate performance. The uniformly coated amorphous layer also enhances the electronic and ionic conductivity of the cathode material, optimizes the charge transfer process, reduces resistance, and improves the battery's charge and discharge efficiency, thereby increasing the battery's energy density. When such a cathode material is applied to a battery, it reduces gas generation during charge and discharge, thus improving battery safety, reducing the risk of thermal runaway, and maximizing the preventative "fire and explosion" capability of the power battery from the cathode material perspective.

[0092] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0093] It should be understood that the technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made to the technical solutions of the present invention without departing from the spirit and scope of the claims are within the scope of protection of the present invention.

Claims

1. A method for preparing a uniformly coated ternary single-crystal cathode material for lithium-ion batteries, characterized in that, include: Ternary single crystal material is prepared by mixing a ternary single crystal material precursor with a lithium source and then performing a sintering and crushing process. The ternary single crystal material is added to the jet coating device, and compressed air is injected to make the ternary single crystal material "boiling". Then, the coating agent solution is sprayed into the jet coating device to coat the ternary single crystal material. The temperature inside the jet coating device is kept higher than the boiling point of the solute in the coating agent solution. Furthermore, the material obtained from the coating process is subjected to secondary sintering and iron removal by sieving to obtain a uniformly coated ternary single-crystal cathode material for lithium-ion batteries.

2. The preparation method according to claim 1, characterized in that, Specifically, it includes: (1) The ternary single crystal material precursor and the lithium source are mixed using a mechanical mixing device to obtain a mixture; wherein the mixing time is ≥10min, the ambient temperature is ≤25℃, and the humidity is ≤25RH% (2) The mixture is sintered once in an oxygen atmosphere to obtain a sintered material; (3) The primary sintering material is coarsely crushed and then placed in an airflow pulverizer for crushing, grading, and cyclone separation to obtain ternary single crystal material; (4) Mix the coating agent with the solvent to form a coating agent solution; add the ternary single crystal material to the jet coating device and inject compressed air to make the ternary single crystal material "boiling"; then spray the coating agent solution into the jet coating device through the nozzle so that the coating agent adheres to the surface of the ternary single crystal material to obtain the coated material. (5) The coating material is sintered in an oxygen atmosphere to obtain a secondary sintered material; (6) The secondary sintering material is fed into a batch mixing device for batch mixing to obtain batch mixed material; wherein, the ambient temperature of the batch mixing process is ≤25℃, the humidity is ≤25RH%, the frequency of the main shaft motor of the batch mixing device is ≥10Hz, and the batch mixing time is ≥10min. (7) The batch mixed material is sieved and iron removed to obtain sieved iron removed material; wherein, the ambient temperature of sieving is ≤25℃, the humidity is ≤25RH%, the mesh size of the sieve is <400 mesh, and the magnetic field strength used for iron removal is ≥1000Gs. (8) The sieved iron-removed material is packaged using a vacuum packaging device to obtain a uniformly coated ternary single crystal cathode material for lithium-ion batteries; wherein the ambient temperature of the packaging process is ≤25℃ and the humidity is ≤25RH.

3. The preparation method according to claim 2, characterized in that: The molar ratio of the lithium source to the ternary single crystal material precursor is a, where 1≤a≤1.04; and / or the ternary single crystal material precursor includes Ni 0.83 Co 0.12 Mn 0.05 (OH)2and / or Ni 0.6 Co 0.1 Mn 0.3 (OH)2; And / or, the lithium source includes LiOH·H2O and / or Li2CO3; And / or, step (1) further includes: mixing the ternary single crystal material precursor, the lithium source, and the dopant containing the X element using a mechanical mixing device; Preferably, the molar ratio of the dopant containing element X to the ternary single-crystal precursor is e:1, where 0 ≤ e ≤ 0.06%; Preferably, the dopant containing element X includes any one or more combinations of oxides, hydroxides, carbonates, and basic carbonates containing element X; preferably, the element X in the dopant contains any one or more combinations of Zn, Ca, Zr, Mg, B, Ti, Nb, Ti, V, W, Sr, Si, Y, Mo, and Al.

4. The preparation method according to claim 2, characterized in that: The temperature of the first sintering is ≥650℃, the sintering time is ≥10h, and the oxygen concentration of the oxygen atmosphere is ≥90%.

5. The preparation method according to claim 2, characterized in that: The particle size D of the ternary single crystal material 10 It is 1.5±0.5μm, D 50 It is 3.5±0.5μm, D 90 It is 5.5 ± 0.5 μm.

6. The preparation method according to claim 2, characterized in that: The coating agent includes oxides, hydroxides, or solid electrolytes; preferably, the oxide includes any one or more combinations of aluminum oxide, boric acid, boron oxide, aluminum oxide, titanium oxide, and tungsten oxide; preferably, the hydroxide includes any one or more combinations of cobalt hydroxide, aluminum hydroxide, magnesium hydroxide, and manganese hydroxide; preferably, the solid electrolyte includes any one or more combinations of LATP, LLZO, and LPSC. And / or, the solvent is a non-flammable inorganic or organic solvent; preferably, the solvent includes any one or more combinations of water, polyethylene glycol, polypropylene glycol, and N-methylpyrrolidone. And / or, the jet coating device includes a material reaction chamber, an injection nozzle, a compressed air pipeline, a feeding port, a dust collection and filtration device, a receiving port, and a heat transfer oil jacket; the injection nozzle is located below the material reaction chamber, the compressed air pipeline is connected to the injection nozzle, a receiving port is located below the material reaction chamber, a heat transfer oil jacket is located around the material reaction chamber, and a feeding port and a dust collection and filtration device are located above the material reaction chamber.

7. The preparation method according to claim 2, characterized in that: The secondary sintering temperature is ≥200℃, the sintering time is ≥5h, and the oxygen concentration in the oxygen atmosphere is ≥85%.

8. The uniformly coated ternary single-crystal cathode material for lithium-ion batteries prepared by the method according to any one of claims 1-7, characterized in that, include: A ternary single-crystal cathode material and a coating layer formed from a coating agent, the ternary single-crystal cathode material having a chemical formula of Li a Ni b Co c Mn d X e O2, wherein 1≤a≤1.05, 0.3≤b≤0.8, 0.02≤c≤0.35, 0.02≤d≤0.35, 0≤e≤0.06%, and X is selected from any one or a combination of multiple of Zn, Ca, Zr, Mg, B, Ti, Nb, Ti, V, W, Sr, Si, Y, Mo, Al.

9. The uniformly coated ternary single-crystal cathode material for lithium-ion batteries according to claim 8, characterized in that: The uniformly coated ternary single-crystal cathode material for lithium-ion batteries has a particle size D50 of 3.4 ± 1 μm and a specific surface area BET of 0.5 ± 0.2 m². 2 / g; And / or, the uniformly coated lithium-ion battery ternary single-crystal cathode material has a first discharge specific capacity of ≥190mAh / g at 0.1C within a voltage range of 2.8~4.5V, and a capacity retention rate of ≥90% after 50 cycles at 1C.

10. The application of the uniformly coated ternary single-crystal cathode material of lithium-ion battery as described in claim 8 or 9 in the preparation of lithium-ion batteries.

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