Single crystal cathode material and producing method of the same

Abstract

To provide a manufacturing method of a single crystal cathode material, and the single crystal cathode material, in which the single crystal cathode material can be directly manufactured by using a polycrystalline precursor, and the single crystal cathode material can be synthesized without performing airflow grinding, a process is simple, the cost is low, and process compatibility is significantly improved.SOLUTION: In a manufacturing method, a lithium source and a nickel-cobalt-manganese precursor are mixed, ball milled, and then subjected to a first roasting treatment to obtain a first main material. A roasting temperature is 650 to 950°C and the roasting time is 15 to 30 h. Then, a first main material and the A source are mixed and ball milled, and then a second roasting treatment is performed to produce a single crystal positive electrode material, in which the roasting temperature is 650 to 950°C and the roasting time is 5 to 15 hours.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a single-crystal positive electrode material and a method for producing the same, and belongs to the technical field of lithium-ion batteries. [Background technology]

[0002] With the vigorous development of the global electric vehicle and battery markets, lithium-ion batteries have become the main battery technology route in the fields of new energy vehicles and energy storage, and the lithium-ion battery cathode material business has become an important part of the lithium battery industry chain.In the early days, polycrystalline lithium battery cathode materials were the mainstream, but with the rapid development of the new energy industry, fast charging and high voltage became market requirements, and monocrystalline cathode materials became the main technological route.

[0003] Because there are no grain boundaries within single-crystal positive electrode materials, grain boundary cracking and secondary particle crushing are less likely to occur during charging and discharging, improving the cycle stability of the battery. Single-crystal materials also have fewer grain boundaries, which reduces side reactions with the electrolyte, helping to improve the safety and lifespan of the battery. Furthermore, single-crystal materials can increase the compaction density, improving the energy density of the battery.

[0004] In the prior art, amorphous precursor sintering and airflow milling are commonly used to produce single-crystalline positive electrode materials. The amorphous precursor sintering process places high demands on the precursor, requiring the precursor's crystalline structure to be adjusted by coprecipitation, which not only makes the process complicated and costly, but also leads to uneven ion precipitation during precipitation, which can result in reduced battery performance. Airflow milling involves pulverizing sintered positive electrode material by airflow collision to obtain single-crystalline positive electrode material. However, airflow milling generates fine powder, which must be separated using a cyclone, resulting in increased production costs. Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the deficiencies of the prior art, the present invention proposes a single-crystal cathode material and a manufacturing method thereof. The method manufactures a single-crystal cathode material using a polycrystalline precursor, eliminating the need for airflow pulverization and significantly improving the process compatibility.

[0006] The manufacturing method of the single-crystal cathode material, which is the technical solution of the present invention, includes the steps: Step 1: Mix a lithium source and a nickel-cobalt-manganese precursor, perform ball milling, and then carry out a first roasting treatment to obtain a first main material. However, the roasting temperature is 650 - 950 °C, and the roasting time is 15 - 30 h. Step 2: Mix the first main material and an A source, perform ball milling, and then carry out a second roasting treatment to manufacture a single-crystal cathode material. However, the roasting temperature is 650 - 950 °C, and the roasting time is 5 - 15 h.

[0007] In the above method, the mass ratio of the first main material to the A source is 1.0:(0.002 - 0.01).

[0008] At the same time, the present invention also provides a single-crystal cathode material obtained by the above manufacturing method, and its general chemical formula is Li

[0011] Ni x Co y Mn z O2·CA, where 1 ≤ A ≤ 1.2, 0 < C ≤ 0.05, 0 ≤ x ≤ 1, 0 ≤ y ≤ 0.5, 0 ≤ z ≤ 0.5, x + y + z = 1, the A source is a coating, and the A source is selected from oxides or carbonates with a large ionic radius.

[0009] Furthermore, the oxide or carbonate with a large ionic radius is one or more of oxides or carbonates of NB, Sr, W, K.

[0010] Furthermore, its average particle size is 2 - 6 μm.

[0011] Furthermore, its specific surface area is 0.5 - 1.5 m 2 / g.

[0012] Furthermore, the total free lithium in the single-crystal cathode material by mass < 1500 ppm.

[0013] The present invention also provides a positive electrode plate including a positive electrode current collector and a positive electrode active material, the positive electrode active material including the above-described single crystal positive electrode material.

[0014] The present invention also provides a battery comprising the above positive plate.

[0015] The present invention also provides an electrical device comprising the battery described above, said battery being used to supply electrical energy. [Effects of the Invention]

[0016] By adopting the above technical solutions, the advantages of the present invention are that the present invention can directly produce a monocrystalline positive electrode material using a polycrystalline precursor, and can synthesize a monocrystalline positive electrode material without airflow milling, which is a simple process, low cost, and greatly improves process compatibility. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is an SEM image of a precursor of the present invention. [Figure 2] 1 is an SEM image of the first main material of the present invention. [Figure 3] 1 is an SEM image of a single-crystal positive electrode material obtained by the manufacturing method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] In order to better understand the technical solutions of the embodiments of the present application, the following will further describe them in conjunction with some preferred embodiments of the present application.

[0019] In this specification, amounts, ratios, and other numerical values may be presented in a range format. Such a range format is for convenience and brevity, and it should be understood flexibly that not only the numerical values explicitly specified as range limitations but also all individual numerical values or sub-ranges included within that range are included as if each numerical value and sub-range were explicitly specified.

[0020] The general chemical formula of the single-crystal cathode material proposed in this application is Li A Ni x Co y Mn z O2·CA, where 1≦A≦1.2, 0<C≦0.05, 0≦x≦1, 0≦y≦0.5, 0≦z≦0.5, x + y + z = 1, A is a coating, and A is selected from oxides or carbonates having a large ionic radius. The oxide or carbonate having a large ionic radius is one or more of oxides or carbonates of NB, Sr, W, K.

[0021] The single-crystal cathode material proposed in this application can be manufactured using a conventional polycrystalline precursor, eliminating the need for air jet milling and significantly improving the process compatibility.

[0022] Compared with an amorphous precursor, a polycrystalline precursor has a high yield and a simple process, resulting in a relatively low cost. And the process of the present invention eliminates the need for air jet milling, reduces the generation of fine powder, and also eliminates the need to separate fine powder with a cyclone, significantly optimizing the synthesis process of the single-crystal cathode material.

[0023] Coating A is used for a low coating. Since it has a relatively large ionic radius, it tends to accumulate on the surface of primary particles, reducing the adhesion force between particles. At high temperatures, the primary particles disperse to form a single-crystal cathode material.

[0024] According to some embodiments of this application, the above single-crystal cathode material has a specific surface area of 2 2 / g, and an average particle size of 2 to 6 μm, and the single crystal positive electrode material contains less than 1500 ppm by mass of total free lithium.

[0025] According to some embodiments of the present application, the single-crystal positive electrode material can be used as a positive electrode material for a lithium-ion battery. For example, the single-crystal positive electrode material, conductive carbon black (SP), and a binder, polyvinylidene fluoride (PVDF), are added to N-methylpyrrolidone (NMP) in a weight ratio of 94:3:3 (the weight ratio of the compound to NMP is 2.1:1), mixed thoroughly, and stirred to form a uniform slurry, thereby producing a positive electrode material (or positive electrode active material). The positive electrode material (or positive electrode active material) can then be applied to an aluminum foil current collector, dried, and pressed to form a positive electrode plate, which can then be used together with a negative electrode plate to form an electrode assembly.

[0026] The present application also provides a battery, specifically a lithium-ion battery, including the electrode assembly, which can be used in digital products, electric vehicles, and energy storage applications.

[0027] For example, a lithium-ion secondary battery typically comprises an electrode assembly, a nonaqueous electrolyte, a separator, and a container. Specifically, the electrode assembly may include a positive electrode plate and a negative electrode plate. As described above, the positive electrode plate may be made of a material including a positive electrode current collector, a positive electrode active material coated on the positive electrode current collector, a conventional binder, a conventional conductive additive, etc. The positive electrode active material may include the compound proposed herein. The negative electrode is made of a material including a current collector, a conventional negative electrode active material coated on the current collector, a conventional binder, a conventional conductive additive, etc. The separator is a PP / PE film commonly used in the industry and serves to separate the positive electrode and the negative electrode from each other. The container is a container for housing the positive electrode, negative electrode, separator, and electrolyte.

[0028] When a 1 mol / L lithium hexafluorophosphate solution is used as the electrolyte, the solvent for the lithium hexafluorophosphate solution is a mixed solvent of dimethyl carbonate (DMC):ethylene carbonate (EC):diethyl carbonate (DEC) = 1:1:1 by mass. The negative electrode material is a mixture of artificial graphite, conductive carbon black, carboxymethyl cellulose, and adhesive in a weight ratio of 95:1:1:3. The positive electrode plate is made by mixing the above compound, conductive carbon black, and PVDF in a weight ratio of 94:3:3. A cell with model number 454261 is then fabricated, and finally a battery is formed.

[0029] The present application also provides, in some embodiments, an electric device including the battery, which is used to provide power, and the electric device can include digital products, electric vehicles, energy storage devices, etc. For example, the battery can be used in portable electronic devices and electric vehicles, and can also be used in energy storage power systems such as hydroelectric, thermal, wind, and solar power plants.

[0030] The present application also provides a method for producing a single crystal positive electrode material, the method comprising: Step 1: Mixing a lithium source and a nickel-cobalt-manganese precursor, ball milling, and then performing a first roasting process to prepare a first primary material, wherein the roasting temperature is 650-950°C and the roasting time is 15-30 hours; Step 2: The first main material and the A source are mixed and ball-milled, and then a second low-temperature roasting treatment is performed to prepare a single-crystalline positive electrode material, in which the roasting temperature is 650 to 950°C and the roasting time is 5 to 15 hours.

[0031] The precursor morphology, as shown in Figure 1, begins with fine needles that combine to form a lamellar structure. After mixing with a lithium source, it is sintered at high temperatures to form a block structure of cathode material. During this process, the fine needles fuse to form a primary block structure, as shown in Figure 2. If the A source is added in Step 1, the A source penetrates the crystals during sintering as the fine needles fuse to form a block structure. This penetrates into the crystal structure during crystal formation and growth, and does not accumulate on the surface of the primary block structure. If the A source is added in Step 2 and mixed and sintered, the crystalline structure of the material is already formed. Due to the limitations of the crystalline material's channels, the A source, with its large ionic radius, cannot penetrate the crystals and instead accumulates on the surface of the primary block structure. This reduces the adhesion between particles, dispersing the primary particles and forming a single-crystal cathode material. Conversely, if the A source is added in Step 1, this effect does not occur.

[0032] Compared with the prior art, the method for producing a single-crystal positive electrode material provided in the examples of the present application can use a polycrystalline precursor to synthesize a single-crystal positive electrode material without airflow pulverization.

[0033] According to some embodiments of the present application, the lithium source is selected from lithium hydroxide monohydrate or lithium carbonate.

[0034] According to some embodiments of the present application, the nickel-cobalt-manganese precursor may be a hydroxide containing nickel, cobalt, and manganese elements, and may have a particle size of 8 μm to 20 μm.

[0035] According to some embodiments of the present application, the mass ratio of the first main material to the A source is 1.0:(0.002 to 0.01), for example, 1:(0.003 to 0.007).

[0036] According to some embodiments of the present application, in the above production method, the first roasting temperature is 650 to 950°C, for example, 700 to 900°C, and the first roasting time is 15 to 30 hours, for example, 20 to 24 hours. The second roasting temperature is 650 to 950°C, for example, 700 to 900°C, and the second roasting time is 5 to 15 hours, for example, 6 to 12 hours.

[0037] According to some embodiments of the present application, in the above-mentioned manufacturing method, the first roasting temperature is 930°C, 900°C, 850°C, 780°C, or 720°C, and the first roasting time is 18 hours, 24 hours, or about 26 hours. The second roasting temperature is 900°C, 850°C, 820°C, 780°C, or 680°C, and the second roasting time is 6 hours, 8 hours, 12 hours, or 14 hours.

[0038] The compounds proposed in the present application, their production methods and uses will be described below using specific examples. Reagents, equipment, etc. not described in the main text of the present application are contents that can be routinely confirmed by those skilled in the art.

[0039] The reagents used in the following examples are shown in Tables 1-1-1 and 1-1-2.

[0040] [Table 1-1-1]

[0041] [Table 1-1-2]

[0042] The instruments and analytical methods used in the following examples are as follows.

[0043] The mixing ball mill equipment is a ShQM type double planetary ball mill manufactured by Lianyungang Chunlong Experimental Instruments Co., Ltd.

[0044] In this application, the specific surface area is tested and analyzed using a fully automatic specific surface area and porosity analyzer (TriStAr II 3020, Micromeritics, USA).

[0045] The test method for free lithium in a compound is as follows.

[0046] Weigh out an appropriate amount of sample (approximately 30 g) accurately to the nearest 0.01 g. Place the sample in a 250 mL Erlenmeyer flask, add a magnetic stir bar, and add 100 mL of deionized water. Place the Erlenmeyer flask on a magnetic stirrer and stir for 30 minutes with the stirrer on. Filter the mixture through filter paper and a funnel. Transfer 50 mL of the filtrate to a 100 mL beaker using a 50 mL pipette and add a magnetic stir bar. Place the beaker on a magnetic stirrer and add two drops of phenolphthalein indicator. Titrate with 0.05 mol / L hydrochloric acid standard titrant until the solution changes color from red to colorless. Record the volume V1 (endpoint 1) of the 0.05 mol / L hydrochloric acid standard titrant. Add two drops of methyl red indicator until the solution changes color from colorless to yellow. Titrate with 0.05 mol / L hydrochloric acid standard titrant until the solution changes color from yellow to orange. Place the beaker in a heating oven and heat until the solution boils (the color of the solution changes from orange to yellow). Remove the 100 mL beaker and cool to room temperature. Place the beaker on the magnetic stirrer again. Titrate with 0.05 mol / L hydrochloric acid standard titrant until the color of the solution changes from yellow to pale red. Record the volume V2 of the 0.05 mol / L hydrochloric acid standard titrant (endpoint 2). Lithium hydroxide: LiOH (wt%) = [V2 - 2 × (V2 - V1)] × 0.05 × 23.946 × 2 × 100 / (m × 1000), lithium carbonate: Li2CO3 (wt%) = (V2 - V1) × 0.05 × 73.886 × 2 × 100 / (m × 1000), free lithium: Li + (wt%)=V2×0.05×6.94×2×100 / (m×1000).

[0047] Average particle size test: The test was carried out using an MS3000 laser particle size distribution measuring device, and the method was as follows.

[0048] An appropriate amount of sample was placed in a 100ml beaker, first rinsed along the inner wall of the beaker with a wash bottle, then rinsed off any sample adhering to the bottom of the beaker with the wash bottle. The amount of pure water added to the beaker was controlled to 20-30mL, and the ultrasonic treatment time was 5min (10s of stirring before, during, and after sonication, respectively, at a stirring speed of approximately 2r / s). 100±10mL of pure water was added to the injector of the MS3000 laser particle size analyzer, the rotation speed was adjusted to 3000r / min, and the start button was clicked. The instrument automatically adjusted the light position, measured the background, and waited for the prompt to proceed. After sonication, the sample was transferred to the stirring tank, rinsed out the beaker with a wash bottle, and confirmed that the sample had been completely transferred. Once the sample was completely added, the software automatically began measurement. Data was automatically saved upon completion.

[0049] The method for manufacturing a battery (cell model number 454261) using the compound produced in the present application is as follows.

[0050] Preparation of positive electrode plate: The compound proposed in this application, conductive carbon black (SP), and binder polyvinylidene fluoride (PVDF) were added to N-methylpyrrolidone (NMP) in a weight ratio of 94:3:3 (the weight ratio of compound to NMP was 2.1:1), mixed thoroughly, and stirred to form a uniform slurry, which was then applied to an aluminum foil current collector, dried, and pressed into a plate.

[0051] Preparation of negative electrode plate: Mix artificial graphite for the negative electrode, conductive carbon black (SP), carboxymethyl cellulose (CMC), and adhesive (SBR) in a weight ratio of 95:1:1:3 with sufficient pure water, stir to form a uniform slurry, apply it to a copper foil current collector, dry it, and press it into a plate.

[0052] The separator is a three-layer composite film material of PP / PE / PP.

[0053] Tabs are spot welded to the pressed positive and negative plates, a separator is inserted, the plate is wound up with a winder and placed in a soft pack jig, the top and side are sealed, and the plate is baked in an oven. After that, 9g of electrolyte is injected in an environment with a relative humidity of less than 1.5% and the plate is chemically formed for 48 hours (Zhejiang Hangzhou KELIP-3AhB06 high-temperature constant-temperature chemical forming system), and then vacuum sealed.

[0054] Dongguan Keyuan KPBAK-03E-02 high-efficiency vacuum drying oven is used for sample drying and high-temperature battery testing.

[0055] The charge-discharge tests for the lithium-ion secondary batteries manufactured in this study were conducted in accordance with the GB / T 18287-2000 test method using a Wuhan BlueElectron battery tester (Wuhan BlueElectron CT2001C tester). The cycle retention rate of materials is significantly affected by differences in battery systems. The battery system used in the experiments was the most commonly used evaluation system. The electrolyte was a 1 mol / L lithium hexafluorophosphate solution. The solvent for the lithium hexafluorophosphate solution was a 1:1:1 mixture of dimethyl carbonate (DMC), ethylene carbonate (EC), and diethyl carbonate (DEC) in a weight ratio of 1:1:1. The negative electrode material was a mixture of artificial graphite, conductive carbon black, carboxymethyl cellulose, and adhesive in a weight ratio of 95:1:1:3. The cell model number was 454261. This allowed for early identification of actual defects in the positive electrode material and determination of its performance.

[0056] Example 1 According to the molar ratio of Li:(Ni+Co+Mn)=1.08:1, lithium hydroxide monohydrate and a precursor (chemical formula: Ni) with a molar ratio of Ni:Co:Mn=1 / 3:1 / 3:1 / 3 were added. 1 / 3 Co 1 / 3 Mn 1 / 3(Oh)2) was added and ball milled, and then ball milled at 40 Hz for 10 minutes to mix uniformly. After that, the material (i.e., the mixed material) was discharged. The mixed material was placed in a muffle furnace and heated to 930°C at a heating rate of 5°C / min in an oxygen atmosphere, sintered for 18 hours, cooled to room temperature, and ball milled at 40 Hz for 10 minutes to obtain the first main material. Then, weigh out the corresponding amount of tungsten oxide so that the mass ratio of the first main material to tungsten oxide was 1.0:0.004, add it to the first main material and ball mill it, ball mill it for 10 minutes at a rotation speed of 40 Hz, put the uniformly mixed material into a muffle furnace, heat it up to 900°C at a heating rate of 10°C / min in an oxygen atmosphere, sinter it for 8 hours, cool it to room temperature, ball mill it for 10 minutes at a rotation speed of 40 Hz, and sieve it through a 300 mesh metal sieve to obtain single crystal positive electrode material 1.

[0057] The particle size, specific surface area, free lithium, and battery test were carried out on the single crystal positive electrode material 1, and the data are shown in Table 1.

[0058] Example 2 According to the molar ratio of Li:(Ni+Co+Mn)=1.06:1, lithium hydroxide monohydrate and a precursor (chemical formula: Ni) with a molar ratio of Ni:Co:Mn=5:2:3 were mixed. 0.5 Co 0.2 Mn 0.3 (Oh)2) was added and ball milled, and then ball milled at 40 Hz for 10 minutes to mix uniformly. After that, the material (i.e., the mixed material) was discharged. The mixed material was placed in a muffle furnace, heated to 900°C at a heating rate of 5°C / min in an oxygen atmosphere, and sintered for 24 hours. It was then cooled to room temperature and ball milled at 40 Hz for 10 minutes to obtain the first main material. Then, a corresponding amount of niobium oxide was weighed out so that the mass ratio of the first main material to niobium oxide was 1.0:0.005, and the corresponding amount of niobium oxide was added to the first main material and ball milled. The mixture was ball milled for 10 minutes at a rotation speed of 40 Hz. The homogeneously mixed material was placed in a muffle furnace and heated to 900°C at a heating rate of 10°C / min in an oxygen atmosphere, sintered for 6 hours, cooled to room temperature, ball milled for 10 minutes at a rotation speed of 40 Hz, and sieved through a 300 mesh metal sieve to obtain single crystal positive electrode material 2.

[0059] The particle size, specific surface area, free lithium, and battery test were carried out on the single crystal positive electrode material 2, and the data are shown in Table 1.

[0060] Example 3 According to the molar ratio of Li:(Ni+Co+Mn)=1.10:1, lithium hydroxide monohydrate and a precursor (chemical formula: Ni) with a molar ratio of Ni:Co:Mn=6:1:3 were added. 0.6 Co 0.1 Mn 0.3 (Oh)2) was added and ball milled, and then ball milled at 40 Hz for 10 minutes to mix uniformly. After that, the material (i.e., the mixed material) was discharged. The mixed material was placed in a muffle furnace, heated to 900°C at a heating rate of 5°C / min in an oxygen atmosphere, and sintered for 24 hours. After that, it was cooled to room temperature and ball milled at 40 Hz for 10 minutes to obtain the first main material. Then, a corresponding amount of tungsten oxide was weighed out so that the mass ratio of the first main material to tungsten oxide was 1.0:0.006, and the corresponding amount of tungsten oxide was added to the first main material and ball-milled. The mixture was ball-milled at a rotation speed of 40 Hz for 10 minutes. The homogeneously mixed material was placed in a muffle furnace, heated to 850°C at a heating rate of 10°C / min in an oxygen atmosphere, and sintered for 12 hours. The mixture was then cooled to room temperature, ball-milled at a rotation speed of 40 Hz for 10 minutes, and sieved through a 300-mesh metal sieve to obtain single-crystal positive electrode material 3.

[0061] The particle size, specific surface area, free lithium, and battery test were carried out on the single crystal positive electrode material 3, and the data are shown in Table 1.

[0062] Example 4 According to the molar ratio of Li:(Ni+Co+Mn)=1.12:1, lithium hydroxide monohydrate and a precursor (chemical formula: Ni) with a molar ratio of Ni:Co:Mn=7:1:2 were mixed. 0.7 Co 0.1 Mn 0.2(Oh)2) was added and ball milled, and then ball milled at 40 Hz for 10 minutes to mix uniformly. After that, the material (i.e., the mixed material) was discharged. The mixed material was placed in a muffle furnace, heated to 850°C at a heating rate of 5°C / min in an oxygen atmosphere, and sintered for 24 hours. After that, it was cooled to room temperature and ball milled at 40 Hz for 10 minutes to obtain the first main material. Then, a corresponding amount of strontium carbonate was weighed out so that the mass ratio of the first main material to strontium carbonate was 1.0:0.004, and the corresponding amount of strontium carbonate was added to the first main material and ball milled at a rotation speed of 40 Hz for 10 minutes. The uniformly mixed material was placed in a muffle furnace, heated to 820°C at a heating rate of 10°C / min in an oxygen atmosphere, and sintered for 14 hours. The material was then cooled to room temperature, ball milled at a rotation speed of 40 Hz for 10 minutes, and sieved through a 300 mesh metal sieve to obtain single crystal positive electrode material 4.

[0063] The particle size, specific surface area, free lithium, and battery test were carried out on the single crystal positive electrode material 4, and the data are shown in Table 1.

[0064] Example 5 According to the molar ratio of Li:(Ni+Co+Mn)=1.08:1, lithium hydroxide monohydrate and a precursor (chemical formula: Ni) with a molar ratio of Ni:Co:Mn=83:07:10 were prepared. 0.83 Co 0.07 Mn 0.10(Oh)2) was added and ball milled, and then ball milled at 40 Hz for 10 minutes to mix uniformly. After that, the material (i.e., the mixed material) was discharged. The mixed material was placed in a muffle furnace and heated to 780°C at a heating rate of 5°C / min in an oxygen atmosphere, sintered for 26 hours, cooled to room temperature, and ball milled at 40 Hz for 10 minutes to obtain the first main material. Then, a corresponding amount of tungsten oxide was weighed out so that the mass ratio of the first main material to tungsten oxide was 1.0:0.006, and the corresponding amount of tungsten oxide was added to the first main material and ball-milled at a rotation speed of 40 Hz for 10 minutes. The homogeneously mixed material was placed in a muffle furnace, heated to 780°C at a heating rate of 10°C / min in an oxygen atmosphere, and sintered for 8 hours. The material was then cooled to room temperature, ball-milled at a rotation speed of 40 Hz for 10 minutes, and sieved through a 300-mesh metal sieve to obtain single-crystal positive electrode material 5.

[0065] The particle size, specific surface area, free lithium, and battery test were carried out on the single crystal positive electrode material 5, and the data are shown in Table 1.

[0066] Example 6 According to the molar ratio of Li:(Ni+Co+Mn)=1.16:1, lithium hydroxide monohydrate and a precursor (chemical formula: Ni) with a molar ratio of Ni:Co:Mn=92:05:03 were prepared. 0.92 Co 0.05 Mn 0.03(Oh)2) was added and ball milled, and then ball milled at 40 Hz for 10 minutes to mix uniformly. After that, the material (i.e., the mixed material) was discharged. The mixed material was placed in a muffle furnace, heated to 720°C at a heating rate of 5°C / min in an oxygen atmosphere, and sintered for 24 hours. After that, it was cooled to room temperature and ball milled at 40 Hz for 10 minutes to obtain the first main material. Then, a corresponding amount of tungsten oxide was weighed out so that the mass ratio of the first main material to tungsten oxide was 1.0:0.004, and the corresponding amount of tungsten oxide was added to the first main material and ball-milled at a rotation speed of 40 Hz for 10 minutes. The homogeneously mixed material was placed in a muffle furnace, heated to 680°C at a heating rate of 10°C / min in an oxygen atmosphere, and sintered for 8 hours. The material was then cooled to room temperature, ball-milled at a rotation speed of 40 Hz for 10 minutes, and sieved through a 300-mesh metal sieve to obtain single-crystal positive electrode material 6.

[0067] The particle size, specific surface area, free lithium, and battery test were carried out on the single crystal positive electrode material 6, and the data are shown in Table 1.

[0068] Example 7 According to the molar ratio of Li:(Ni+Co+Mn)=1.08:1, lithium hydroxide monohydrate and a precursor (chemical formula: Ni) with a molar ratio of Ni:Co:Mn=97:02:01 were added. 0.97 Co 0.02 Mn 0.01(Oh)2) was added and ball milled, and then ball milled at a rotation speed of 40 Hz for 10 minutes to mix uniformly. After that, the material (i.e., the mixed material) was discharged. The mixed material was placed in a muffle furnace, heated to 650°C at a heating rate of 5°C / min in an oxygen atmosphere, and sintered for 30 hours. After that, it was cooled to room temperature and ball milled at a rotation speed of 40 Hz for 10 minutes to obtain the first main material. Then, a corresponding amount of tungsten oxide was weighed out so that the mass ratio of the first main material to tungsten oxide was 1.0:0.004, and the corresponding amount of tungsten oxide was added to the first main material and ball-milled at a rotation speed of 40 Hz for 10 minutes. The homogeneously mixed material was placed in a muffle furnace, heated to 650°C at a heating rate of 10°C / min in an oxygen atmosphere, and sintered for 15 hours. The material was then cooled to room temperature, ball-milled at a rotation speed of 40 Hz for 10 minutes, and sieved through a 300-mesh metal sieve to obtain single-crystal positive electrode material 7.

[0069] The particle size, specific surface area, free lithium, and battery test were carried out on the single crystal positive electrode material 7, and the data are shown in Table 1.

[0070] Example 8 According to the molar ratio of Li:(Ni+Co+Mn)=1.06:1, lithium hydroxide monohydrate and a precursor (chemical formula: Ni) with a molar ratio of Ni:Co:Mn=1 / 3:1 / 3:1 / 3 were added. 1 / 3 Co 1 / 3 Mn 1 / 3(Oh)2) was added and ball milled, and then ball milled at 40 Hz for 10 minutes to mix uniformly. After that, the material (i.e., the mixed material) was discharged. The mixed material was placed in a muffle furnace and heated to 950°C at a heating rate of 5°C / min in an oxygen atmosphere, sintered for 15 hours, cooled to room temperature, and ball milled at 40 Hz for 10 minutes to obtain the first main material. Then, a corresponding amount of tungsten oxide was weighed out so that the mass ratio of the first main material to tungsten oxide was 1.0:0.004, and the corresponding amount of tungsten oxide was added to the first main material and ball-milled. The mixture was ball-milled at a rotation speed of 40 Hz for 10 minutes. The homogeneously mixed material was placed in a muffle furnace, heated to 950°C at a heating rate of 10°C / min in an oxygen atmosphere, and sintered for 5 hours. The mixture was then cooled to room temperature, ball-milled at a rotation speed of 40 Hz for 10 minutes, and sieved through a 300-mesh metal sieve to obtain single-crystal positive electrode material 8.

[0071] The particle size, specific surface area, free lithium, and battery test were carried out on the single crystal positive electrode material 1, and the data are shown in Table 1.

[0072] Comparative Example 1 Lithium hydroxide monohydrate and an amorphous precursor with a molar ratio of Ni:Co:Mn = 83:07:10 were added in a Li:(Ni+Co+Mn) = 1.12:1 molar ratio, and ball milled at 40 Hz for 10 min. After uniform mixing, the material (i.e., the mixed material) was discharged. The mixed material was placed in a muffle furnace and heated to 800 °C at a heating rate of 5 °C / min under an oxygen atmosphere. After sintering for 20 hours, it was cooled to room temperature, ball milled at 40 Hz for 10 min, and sieved through a 300-mesh metal sieve to obtain comparative single-crystal positive electrode material D1.

[0073] The particle size, specific surface area, free lithium, and battery test were carried out on the single crystal positive electrode material D1, and the data are shown in Table 1.

[0074] Comparative Example 2 According to the molar ratio of Li:(Ni+Co+Mn)=1.10:1, lithium hydroxide monohydrate and a precursor (chemical formula: Ni) with a molar ratio of Ni:Co:Mn=83:07:10 were mixed. 0.83 Co0.07 Mn 0.1 (Oh)2) was added and ball milled at 40 Hz for 10 minutes to mix uniformly, after which the material (i.e., the mixed material) was discharged. The mixed material was placed in a muffle furnace and heated to 830°C at a heating rate of 5°C / min in an oxygen atmosphere, sintered for 28 hours, cooled to room temperature, ball milled at 40 Hz for 10 minutes, air-pulverized, and sieved through a 300-mesh metal sieve to obtain comparative single-crystal positive electrode material D2.

[0075] The particle size, specific surface area, free lithium, and battery test data for the single crystal positive electrode material D2 are shown in Table 1.

[0076] [Table 1]

[0077] As shown in Table 1, the single crystal positive electrode material prepared according to the above examples of the present application has a total free lithium content of <1500 ppm and a specific surface area of ​​0.5-1.5 m 2 / g, particle size of 2.0 to 6.0 μm, and has a single crystal morphology of primary particles.

[0078] As can be seen from Table 1, in the examples, all of the methods of the present invention can achieve the synthesis of single crystalline positive electrode materials. Compared with the two current methods for synthesizing single crystalline positive electrode materials, the present invention does not rely on precursors and can single crystallize any precursor. It does not require air-flow milling to achieve single crystallization, effectively avoiding damage to primary particles caused by air-flow milling and improving the stability of the material.

Claims

1. Step 1: Mixing a lithium source and a nickel-cobalt-manganese polycrystalline precursor, ball milling the mixture, and then performing a first roasting treatment to obtain a first main material, wherein the roasting temperature is 650-950°C and the roasting time is 15-30 hours; Step 2: The first main material and the A source are mixed and ball-milled, followed by a second roasting treatment to prepare a monocrystalline positive electrode material, wherein the roasting temperature is 650-950°C, the roasting time is 5-15h, the A source is a coating, and the A source is selected from oxides or carbonates with large ionic radii, and the oxides or carbonates with large ionic radii are one or more of oxides or carbonates of Nb, Sr, and W, and the general chemical formula of the monocrystalline positive electrode material is Li Ａ Ni ｘ Co ｙ Mn ｚ O ２ CA, where 1≦A≦1.2, 0<C≦0.05, 0≦x≦1, 0≦y≦0.5, 0≦z≦0.5, and x+y+z=1 A method for producing a single crystal positive electrode material, comprising the steps of:

2. 2. The method for producing a single crystal positive electrode material according to claim 1, wherein the mass ratio of the first main material to the A source is 1.0:(0.002 to 0.01).

3. A single crystal positive electrode material, produced by the production method according to claim 1 or 2.

4. The single crystal positive electrode material according to claim 3, wherein the average particle size is 2 to 6 μm.

5. Specific surface area is 0.5 to 1.5 m ２ The single crystal positive electrode material according to claim 3, wherein the SiO2 content is 1 / g.

6. 4. The single crystal cathode material of claim 3, characterized in that there is <1500 ppm total free lithium in the single crystal cathode material by mass.

7. A positive electrode plate comprising a positive electrode current collector and a positive electrode active material, wherein the positive electrode active material comprises the single crystal positive electrode material according to any one of claims 3 to 6.

8. A battery comprising the positive plate of claim 7.

9. 10. An electrical device, characterized in that it includes a battery according to claim 8, used to supply electrical energy.

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