High-entropy nickel-rich ternary precursor, preparation method thereof, positive electrode material and battery

Abstract

This invention provides a high-entropy nickel-rich ternary precursor and its preparation method, as well as a cathode material and a battery. The preparation method includes: introducing a mixed metal source solution, a precipitant solution, a complexing agent solution, and a first dopant source solution into a first base liquid to perform a first coprecipitation reaction; washing and solid-liquid separation of the reaction slurry after the first coprecipitation reaction to obtain seed crystals; preparing a seed slurry from the seed crystals; and introducing the mixed metal source solution, precipitant solution, complexing agent solution, a second dopant source solution, and the seed slurry into a second base liquid to perform a second coprecipitation reaction to obtain the high-entropy nickel-rich ternary precursor. The preparation method of this invention achieves a balance between low mixing, high stability, and fast conduction by first preparing a high-entropy core that suppresses lithium-nickel mixing, and then constructing a high-entropy gradient layer with wide Li ion diffusion channels during the growth stage. Furthermore, the continuous production method results in high-yield precursors, enabling large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a high-entropy nickel-rich ternary precursor and its preparation method, cathode material and battery. Background Technology

[0002] Lithium-ion batteries are widely used in various electronic fields due to their high energy density, long cycle life, and high output voltage. As the performance requirements for electronic devices continue to increase, the energy density requirements for lithium-ion batteries are also gradually rising. As a crucial component of lithium-ion batteries, the performance of the positive electrode active material directly affects the battery's overall performance. High-nickel positive electrode materials possess high energy density, but as the nickel content increases, the material's stability deteriorates, and a serious lithium-nickel mixing problem arises. Since the structure and physicochemical properties of high-nickel ternary positive electrode materials are inherited from high-nickel ternary precursors, modifying the high-nickel ternary precursors can improve the electrochemical performance of the positive electrode material. Summary of the Invention

[0003] The purpose of this invention is to provide a high-entropy nickel-rich ternary precursor and its preparation method, as well as a cathode material and a battery. The preparation method first prepares a high-entropy core that suppresses lithium-nickel mixing, and then prepares a high-entropy gradient layer with wide Li ion diffusion channels during the growth stage. This achieves a balance between low mixing, high stability and fast conduction. Furthermore, the precursor produced by the continuous method has a large yield and can be mass-produced.

[0004] To achieve this objective, the present invention adopts the following technical solution:

[0005] In a first aspect, the present invention provides a method for preparing a high-entropy nickel-rich ternary precursor, the method comprising the following steps:

[0006] (1) The mixed metal source solution, precipitant solution, complexing agent solution and first doped source solution are passed into the first bottom liquid to carry out the first coprecipitation reaction. After the first coprecipitation reaction, the reaction slurry is washed and solid-liquid separation is performed to obtain seed crystals.

[0007] The doping element in the first doped source solution includes any one or a combination of at least two of Mg, Zn or Ga;

[0008] (2) The seed crystals described in step (1) are slurried to obtain a seed crystal slurry. The mixed metal source solution, precipitant solution, complexing agent solution, second doping source solution and the seed crystal slurry are introduced into the second bottom liquid to carry out the second co-precipitation reaction to obtain the high-entropy nickel-rich ternary precursor.

[0009] The second base liquid includes the seed crystals described in step (1);

[0010] The doping element in the second doped source solution includes any one or a combination of at least two of Zr, Nb, or Sc.

[0011] This invention employs a continuous two-stage doping method to prepare a precursor with a multi-element distribution. The seed crystal preparation stage involves doping with Li... + Elements with similar radii (Mg) 2+ / Zn 2+ / Ga 3+ This involves constructing a high-entropy core that can precisely suppress lithium-nickel mixing, thereby inhibiting lithium-nickel mixing at its source; during the growth stage, elements with larger radii (Zr) are doped into it. 4+ / Nb 5+ / Sc 3+ This invention constructs a high-entropy gradient layer with wide Li-ion diffusion channels, achieving a balance between low mixing, high stability, and fast conduction. Furthermore, the continuous method produces a large yield of precursors, making it suitable for large-scale production. In addition, the obtained seed crystals are prepared into a seed slurry, which is then reacted with other raw materials in a second substrate containing the seed crystals. This yields a precursor with a wide particle size distribution, allowing smaller particles to fill the pores between larger particles during cathode material preparation, thus increasing the compaction density of the cathode and directly improving the volumetric energy density of the battery.

[0012] Preferably, in step (2), the second coprecipitation reaction is stopped when the maximum particle size Dmax of the product is 2-3 times the target particle size D50, for example, 2 times, 2.25 times, 2.5 times, 2.75 times or 3.0 times.

[0013] When the maximum particle size Dmax of the product of this invention is 2-3 times the target particle size D50, the process is stopped. If Dmax is too small or too large compared to the target particle size D50, the particle size distribution range of the precursor will be too small or too large, which will affect the compaction density of the cathode material and further affect the volumetric energy density of the battery.

[0014] Preferably, the target particle size D50 is 10-12 μm, for example, it can be 10 μm, 10.5 μm, 11 μm, 11.5 μm or 12 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0015] Preferably, in step (2), when the second coprecipitation reaction reaches the target particle size D50, the feed flow rate of the seed slurry is dynamically adjusted so that the product particle size D50 is maintained at the target particle size D50. The slurry overflowing from the reaction is collected and stored in the overflow vessel and then thickened.

[0016] Preferably, the temperature of the overflow vessel is 40-80°C, for example, 40°C, 50°C, 60°C, 70°C or 80°C, and the rotation speed is 200-500 r / min, for example, 200 r / min, 300 r / min, 400 r / min or 500 r / min, and a protective atmosphere is maintained.

[0017] Preferably, when the overflow material in the overflow vessel is 70-85% of the overflow vessel volume, for example, it can be 70%, 75%, 80% or 85%, it is subjected to thickening treatment.

[0018] Preferably, after the reaction is stopped, the slurry in the reactor and the overflow vessel of the second coprecipitation reaction is aged, washed and dried.

[0019] Preferably, the aging temperature is 40-80℃, for example, 40℃, 50℃, 60℃, 70℃ or 80℃, and the pH is 10-12, for example, 10, 10.5, 11, 11.5 or 12, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, the total alkali concentration of the aging system is 10-40 g / L, for example, it can be 10 g / L, 20 g / L, 30 g / L or 40 g / L, and the rotation speed is 200-500 r / min, for example, it can be 200 r / min, 300 r / min, 400 r / min or 500 r / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] Preferably, the washing includes alkaline washing and water washing.

[0022] Preferably, the drying temperature is 80-120℃, for example, it can be 80℃, 90℃, 100℃, 110℃ or 120℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] Preferably, in step (2), before the second coprecipitation reaction reaches the target particle size D50, the flow rate of the seed slurry is 10-30% of the flow rate of the mixed metal source solution in step (2), for example, it can be 10%, 20% or 30%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the solid content of the seed slurry in step (2) is 20-100 g / L, for example, it can be 20 g / L, 40 g / L, 60 g / L, 80 g / L or 100 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, the feed flow rate of the second doped source solution in step (2) is 0.1-0.3% of the volumetric flow rate of the mixed metal source solution in step (2), for example, it can be 0.1%, 0.15%, 0.2%, 0.25% or 0.3%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, in step (2), the doping elements in the second doping source solution include Zr, Nb, and Sc.

[0027] The present invention preferably incorporates three elements, Zr, Nb, and Sc, during the growth stage, wherein Zr... 4+ Large radius and high charge (Nb) act as "lattice pillars," strengthening the structure and suppressing phase transitions. However, their poor ionic conductivity leads to a sharp drop in positive electrode rate performance, and they cannot specifically improve the surface's resistance to electrolyte corrosion. 5+ It can improve TM-O bond strength, reduce oxygen release, and lower the risk of thermal runaway. 3+ Primarily responsible for "ion conduction" and optimizing Li + Migration path, improve conduction efficiency. Therefore, the synergy of the three elements solves the "performance contradiction" when doped with a single or two elements, such as the balance between structural stability and conduction efficiency, through the high entropy effect.

[0028] Preferably, in step (2), the mass concentration of the dopant element in the second dopant source solution is 1-5 g / L, for example, it can be 1 g / L, 2 g / L, 3 g / L, 4 g / L or 5 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] Preferably, the temperature of the second coprecipitation reaction in step (2) is 40-80℃, for example, 40℃, 50℃, 60℃, 70℃ or 80℃, the pH is 9-11, for example, 9, 9.5, 10, 10.5 or 11, and the rotation speed is 400-700r / min, for example, 400r / min, 500r / min, 600r / min or 700r / min, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] Preferably, in the system of the second coprecipitation reaction in step (2), the concentration of the complexing agent is 5-8 g / L, for example, it can be 5 g / L, 6 g / L, 7 g / L or 8 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, the second base liquid in step (2) further includes a precipitant, a complexing agent, a dispersant, and pure water.

[0032] Preferably, the dispersant comprises polyethylene glycol and / or CTAB (hexadecyltrimethylammonium bromide).

[0033] Preferably, in step (2), the concentration of the seed crystal in the second base solution is 50-120 g / L, for example, it can be 50 g / L, 70 g / L, 90 g / L, 100 g / L or 120 g / L; the concentration of the dispersant is 0.3-0.5 g / L, for example, it can be 0.3 g / L, 0.35 g / L, 0.4 g / L, 0.45 g / L or 0.5 g / L; and the concentration of the complexing agent is 5-8 g / L, for example, it can be 5 g / L, 6 g / L, 7 g / L or 8 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] Preferably, in step (2), the temperature of the second base liquid is 40-80℃, for example, it can be 40℃, 50℃, 60℃, 70℃ or 80℃, the pH is 9-11, for example, it can be 9, 9.5, 10, 10.5 or 11, and the rotation speed is 400-700r / min, for example, it can be 400r / min, 500r / min, 600r / min or 700r / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, the seed crystal size D50 in step (1) is 30-50% of the target seed crystal size D50, for example, it can be 30%, 35%, 40%, 45% or 50%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] Preferably, the doping elements in the first doping source solution in step (1) include Mg, Zn and Ga.

[0037] The seed crystals of this invention are preferably doped with Mg, Zn and Ga, which can improve the overall performance of the material.

[0038] Preferably, the feed flow rate of the first doped source solution in step (1) is 0.1-0.3% of the volumetric flow rate of the mixed metal source solution in step (1), for example, it can be 0.1%, 0.15%, 0.2%, 0.25% or 0.3%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] Preferably, in step (1), the mass concentration of the dopant element in the first dopant source solution is 1-5 g / L, for example, it can be 1 g / L, 2 g / L, 3 g / L, 4 g / L or 5 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] Preferably, the temperature of the first coprecipitation reaction in step (1) is 40-80℃, for example, 40℃, 50℃, 60℃, 70℃ or 80℃, the pH is 9-11, for example, 9, 9.5, 10, 10.5 or 11, the rotation speed is 400-700r / min, for example, 400r / min, 500r / min, 600r / min or 700r / min, and the concentration of the complexing agent in the system is 5-8g / L, for example, 5g / L, 6g / L, 7g / L or 8g / L, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] Preferably, the first base liquid in step (1) includes a precipitant, a complexing agent, a dispersant, and pure water.

[0042] Preferably, in step (1), the temperature of the first base liquid is 40-80℃, for example, it can be 40℃, 50℃, 60℃, 70℃ or 80℃, the pH is 11-12, for example, it can be 11, 11.2, 11.4, 11.6, 11.8 or 12, and the rotation speed is 400-700r / min, for example, it can be 400r / min, 500r / min, 600r / min or 700r / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] Preferably, in step (1), the concentration of the dispersant in the first base liquid is 0.3-0.5 g / L, for example, it can be 0.3 g / L, 0.35 g / L, 0.4 g / L, 0.45 g / L or 0.5 g / L, and the concentration of the complexing agent is 5-8 g / L, for example, it can be 5 g / L, 6 g / L, 7 g / L or 8 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] Preferably, in the mixed metal source solution described in steps (1) and (2), the molar ratio of nickel ions, cobalt ions, and manganese ions is x:y:(1-xy), where 0.80≤x≤0.97, for example, can be 0.8, 0.85, 0.87, 0.9, 0.95, or 0.97, and 0≤y≤0.15, for example, can be 0, 0.05, 0.1, or 0.15, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] Preferably, the total concentration of the mixed metal source solution in steps (1) and (2) is 80-120 g / L, for example, it can be 80 g / L, 90 g / L, 100 g / L, 110 g / L or 120 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0046] Preferably, the concentration of the precipitant solution in steps (1) and (2) is 200-500 g / L, for example, it can be 200 g / L, 300 g / L, 400 g / L or 500 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0047] Preferably, the precipitant solution in steps (1) and (2) comprises any one or a combination of at least two of sodium hydroxide, sodium carbonate, or ammonium carbonate.

[0048] Preferably, the concentration of the complexing agent solution in steps (1) and (2) is 9-15 mol / L, for example, it can be 9 mol / L, 11 mol / L, 13 mol / L or 15 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0049] Preferably, the complexing agent solution in steps (1) and (2) comprises any one or a combination of at least two of ammonia, oxalic acid, citric acid, ascorbic acid, or EDTA.

[0050] In a second aspect, the present invention provides a high-entropy nickel-rich ternary precursor, which is prepared by the preparation method described in the first aspect.

[0051] Thirdly, the present invention provides a cathode material obtained by mixing and sintering a lithium source and a high-entropy nickel-rich ternary precursor as described in the second aspect.

[0052] Preferably, the sintering temperature is 600-850℃, for example, 600℃, 650℃, 700℃, 750℃, 800℃ or 850℃, the time is 15-20h, for example, 15h, 16h, 17h, 18h, 19h or 20h, the heating rate is 1-3℃ / min, for example, 1℃ / min, 1.5℃ / min, 2℃ / min, 2.5℃ / min or 3℃ / min, and the sintering is carried out in a pure oxygen atmosphere.

[0053] Preferably, the molar ratio of lithium ions in the lithium source to total metal ions in the high-entropy nickel-rich ternary precursor is (0.95-1.05):1, for example, it can be 0.95:1, 0.97:1, 0.99:1, 1.01:1, 1.03:1 or 1.05:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0054] Fourthly, the present invention provides a battery comprising the positive electrode material as described in the third aspect.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] This invention employs a continuous two-stage doping method to prepare a precursor with a multi-element distribution. The seed crystal preparation stage constructs a high-entropy core (doped with Mg) capable of precisely suppressing lithium-nickel mixing. 2+ / Zn 2+ / Ga 3+ During the growth stage, a high-entropy gradient layer (doped with Zr) with wide Li ion diffusion channels is constructed. 4+ / Nb 5+ / Sc 3+ This method achieves a balance between low mixing, high stability, and fast conduction. Furthermore, the continuous production of precursors results in high yields, making it suitable for large-scale production. In addition, the present invention prepares the obtained seed crystals into a seed slurry, which is then reacted with other raw materials in a second bottom liquid containing the seed crystals. This yields a precursor with a wide particle size distribution. As a result, when preparing the cathode material, the small particles can fill the pores between the large particles, increasing the compaction density of the cathode and thus directly improving the volumetric energy density of the battery. Attached Figure Description

[0057] Figure 1 This is a SEM image of the cathode material obtained in Example 1 of the present invention.

[0058] Figure 2 This is a SEM image of the cathode material obtained in Comparative Example 1 of the present invention.

[0059] Figure 3 This is a SEM image of the cathode material obtained in Comparative Example 2 of the present invention. Detailed Implementation

[0060] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0061] Example 1

[0062] This embodiment provides a method for preparing a high-entropy nickel-rich ternary precursor, the method comprising the following steps:

[0063] (1) Prepare a mixed metal source solution with a Ni ion, Co ion and Mn ion molar ratio of 95:2:3 and a transition metal mass concentration of 80 g / L; prepare a sodium hydroxide solution with a concentration of 400 g / L as a precipitant solution; prepare an ammonia solution with a concentration of 10 mol / L as a complexing agent solution; prepare MgSO4, ZnSO4 and Ga2(SO4)3 in a Mg ion, Zn ion and Ga ion molar ratio of 1:1:1 to prepare a seed doping solution with a metal element mass concentration of 3 g / L; prepare Zr(SO4)2, Sc2(SO4)3 and Nb2(SO4)5 in a Zr ion, Sc ion and Nb ion molar ratio of 1:1:1 to prepare a growth doping solution with a metal element mass concentration of 3 g / L.

[0064] (2) Seed doping stage: Sodium hydroxide, ammonia, dispersant (specifically polyethylene glycol) and pure water are added to the reactor as the first base liquid. Protective gas is introduced, and the temperature is controlled at 50℃, pH is controlled at 12, total ammonia concentration is controlled at 6g / L, rotation speed is controlled at 600r / min, and dispersant concentration is controlled at 0.3g / L. After 2 hours of aeration, the mixed metal source solution, precipitant solution, complexing agent solution and seed doping solution are added to the reactor separately to start the reaction. The rotation speed is controlled at 600r / min, the reaction temperature is controlled at 50℃, pH is controlled at 11, total ammonia concentration is controlled at 3g / L, and the feed flow rate of seed doping solution is 0.2% of the volume flow rate of mixed metal source solution. When the seed particle size D50 reaches 3μm (30% of the target particle size D50), all feed is stopped, and the seed slurry in the reactor is washed with pure water, filtered, and compacted to obtain multi-element doped seed filter cake.

[0065] (3) Take the seed filter cake and add it to pure water, and stir it to form a seed slurry with a mass concentration of 100g / L;

[0066] (4) Use 0.5 kg of seed filter cake, 20 kg of pure water, ammonia, precipitant solution and dispersant (specifically polyethylene glycol) as the second base liquid. Under a protective atmosphere, control the reaction temperature at 50°C, the pH of the base liquid at 10, the total ammonia at 6 g / L, the rotation speed at 400 r / min, the concentration of the dispersant at 0.3 g / L, and the concentration of the seed crystal at 100 g / L. After ventilating for 2 hours, add the mixed metal source solution, precipitant solution, complexing agent solution, growth doping solution and the seed slurry described in step (3) into the reactor to start the reaction. Control the rotation speed at 600 r / min, the reaction temperature at 50°C, the pH at 9, the total ammonia concentration at 5 g / L, and the feed flow rate of the growth doping solution as a mixture. The flow rate of the metal source solution is 0.2% of the volumetric flow rate, and the flow rate of the seed slurry is 30% of the flow rate of the mixed metal source solution. The flow rate of the seed slurry is dynamically adjusted to keep the precursor particle size D50 in the reactor stable at the target particle size D50 (specifically 10 μm). That is, when the particle size begins to stabilize, the slurry overflowing from the reactor is collected and stored in the overflow vessel. The reaction temperature in the overflow vessel is maintained at 50℃, the rotation speed is maintained at 500 r / min, and an inert atmosphere is maintained. When the overflow material is close to 85% of the reactor volume, the overflow slurry is cleared and solidified using a thickener, and some mother liquor is discharged. When the maximum particle size Dmax in the reactor exceeds 2.5 times the target particle size D50 (specifically 25 μm), all feeding is stopped. The slurry in the reactor and the overflow vessel was aged for 8 hours, with the aging temperature controlled at 60℃, the pH controlled at 11, the total alkali concentration at 40 g / L, and the rotation speed at 300 r / min. After aging, the slurry was washed with alkali 4 times and with water 4 times. Finally, it was dried at a low temperature of 120℃ to obtain the high-entropy nickel-rich ternary precursor.

[0067] This embodiment also provides a method for preparing a cathode material, the method comprising the following steps:

[0068] The high-entropy nickel-rich ternary precursor obtained in this embodiment is mixed with lithium hydroxide, wherein the molar ratio of lithium ions in lithium hydroxide to total metal ions in the high-entropy nickel-rich ternary precursor is 1.05:1. The mixture is then sintered under pure oxygen conditions to obtain the cathode material, wherein the sintering temperature is 750°C, the time is 20 h, and the heating rate is 3°C / min.

[0069] The SEM image of the cathode material obtained in this embodiment is as follows: Figure 1 As shown, by Figure 1 It can be seen that the material has a wide particle size distribution range, with small particles filling the gaps between large particles.

[0070] Example 2

[0071] This embodiment provides a method for preparing a high-entropy nickel-rich ternary precursor. Except for step (2), where the seed particle size D50 is 4 μm (40% of the target particle size D50), the preparation method is the same as in Example 1.

[0072] This embodiment also provides a method for preparing a cathode material. Except for using the high-entropy nickel-rich ternary precursor described in this embodiment, the preparation method is the same as in Example 1.

[0073] Example 3

[0074] This embodiment provides a method for preparing a high-entropy nickel-rich ternary precursor. Except for step (2), where the seed particle size D50 is 5 μm (50% of the target particle size D50), the preparation method is the same as in Example 1.

[0075] This embodiment also provides a method for preparing a cathode material. Except for using the high-entropy nickel-rich ternary precursor described in this embodiment, the preparation method is the same as in Example 1.

[0076] Example 4

[0077] This embodiment provides a method for preparing a high-entropy nickel-rich ternary precursor. Except for step (1), in which the seed doping solution contains only Zn ions, the preparation method is the same as in Example 1.

[0078] This embodiment also provides a method for preparing a cathode material. Except for using the high-entropy nickel-rich ternary precursor described in this embodiment, the preparation method is the same as in Example 1.

[0079] Example 5

[0080] This embodiment provides a method for preparing a high-entropy nickel-rich ternary precursor. Except for step (1), in which the seed doping solution contains only Zn ions and the growth doping solution contains only Nb ions and Sc ions, the preparation method is the same as in Example 1.

[0081] This embodiment also provides a method for preparing a cathode material. Except for using the high-entropy nickel-rich ternary precursor described in this embodiment, the preparation method is the same as in Example 1.

[0082] Example 6

[0083] This embodiment provides a method for preparing a high-entropy nickel-rich ternary precursor. Except for step (1), in which the seed doping solution contains only Zn ions and the growth doping solution contains only Zr ions, the preparation method is the same as in Example 1.

[0084] This embodiment also provides a method for preparing a cathode material. Except for using the high-entropy nickel-rich ternary precursor described in this embodiment, the preparation method is the same as in Example 1.

[0085] Example 7

[0086] This embodiment provides a method for preparing a high-entropy nickel-rich ternary precursor. Except for step (4), which states that all feed should be stopped when the maximum particle size Dmax in the reactor exceeds 1.5 times the target particle size D50 (Dmax is specifically 15 μm), the preparation method is the same as in Example 1.

[0087] This embodiment also provides a method for preparing a cathode material. Except for using the high-entropy nickel-rich ternary precursor described in this embodiment, the preparation method is the same as in Example 1.

[0088] Example 8

[0089] This embodiment provides a method for preparing a high-entropy nickel-rich ternary precursor. Except for step (4), which states that all feed should be stopped when the maximum particle size Dmax in the reactor exceeds three times the target particle size D50 (Dmax is specifically 30 μm), the preparation method is the same as in Example 1.

[0090] This embodiment also provides a method for preparing a cathode material. Except for using the high-entropy nickel-rich ternary precursor described in this embodiment, the preparation method is the same as in Example 1.

[0091] Example 9

[0092] This embodiment provides a method for preparing a high-entropy nickel-rich ternary precursor, the method comprising the following steps:

[0093] (1) Prepare a mixed metal source solution with a Ni ion, Co ion and Mn ion molar ratio of 90:5:5 and a transition metal mass concentration of 120 g / L; prepare a sodium hydroxide solution with a concentration of 200 g / L as a precipitant solution; prepare an ammonia solution with a concentration of 15 mol / L as a complexing agent solution; prepare MgSO4, ZnSO4 and Ga2(SO4)3 in a Mg ion, Zn ion and Ga ion molar ratio of 1:1:1 to prepare a seed doping solution with a metal element mass concentration of 5 g / L; prepare Zr(SO4)2, Sc2(SO4)3 and Nb2(SO4)5 in a Zr ion, Sc ion and Nb ion molar ratio of 1:1:1 to prepare a growth doping solution with a metal element mass concentration of 5 g / L.

[0094] (2) Seed doping stage: Sodium hydroxide, ammonia, dispersant (specifically CTAB) and pure water are added to the reactor as the first base liquid. Protective gas is introduced, and the temperature is controlled at 80℃, pH is controlled at 11, total ammonia concentration is controlled at 8g / L, rotation speed is controlled at 400r / min, and dispersant concentration is controlled at 0.5g / L. After 2 hours of aeration, the mixed metal source solution, precipitant solution, complexing agent solution and seed doping solution are added to the reactor separately to start the reaction. The rotation speed is controlled at 400r / min, the reaction temperature is controlled at 80℃, pH is controlled at 9, total ammonia concentration is controlled at 8g / L, and the feed flow rate of seed doping solution is 0.3% of the volume flow rate of mixed metal source solution. When the seed particle size D50 reaches 3μm, all feed is stopped, and the seed slurry in the reactor is washed with pure water, filtered and compacted to obtain multi-element doped seed filter cake.

[0095] (3) Take the seed filter cake and add it to pure water, and stir it to form a seed slurry with a mass concentration of 30 g / L;

[0096] (4) Using seed filter cake, pure water, ammonia, precipitant solution and dispersant (specifically CTAB) as the second base liquid, under a protective atmosphere, the reaction temperature is controlled at 80℃, the pH of the base liquid is controlled at 11, the total ammonia is controlled at 6g / L, the rotation speed is controlled at 400r / min, the concentration of the dispersant is controlled at 0.5g / L, and the concentration of the seed crystal is controlled at 120g / L. After ventilating for 2 hours, the mixed metal source solution, precipitant solution, complexing agent solution, growth doping solution and the seed slurry described in step (3) are diverted into the reactor to start the reaction. The rotation speed is controlled at 400r / min, the reaction temperature is controlled at 80℃, the pH is controlled at 10, the total ammonia concentration is controlled at 5g / L, and the feed flow rate of the growth doping solution is the mixed metal source solution. The flow rate of the liquid volumetric flow rate is 0.3%, and the flow rate of the seed slurry is 10% of the flow rate of the mixed metal source solution. The flow rate of the seed slurry feed is dynamically adjusted to keep the precursor particle size D50 in the reactor stable at the target particle size D50 (specifically 12μm). That is, when the particle size begins to stabilize, the slurry overflowing from the reactor is collected and stored in the overflow vessel. The reaction temperature in the overflow vessel is maintained at 80℃, the rotation speed is maintained at 200r / min, and an inert atmosphere is maintained. When the overflow material is close to 70% of the reactor volume, the overflow slurry is cleared and solidified using a thickener, and some mother liquor is discharged. When the maximum particle size Dmax in the reactor exceeds 2.5 times the target particle size D50 (Dmax is specifically 30μm), all feeding is stopped. The slurry in the reactor and the overflow vessel was aged for 8 hours, with the aging temperature controlled at 50℃, the pH controlled at 10, the total alkali concentration at 10 g / L, and the rotation speed at 500 r / min. After aging, the slurry was washed with alkali 4 times and with water 4 times. Finally, it was dried at a low temperature of 80℃ to obtain the high-entropy nickel-rich ternary precursor.

[0097] This embodiment also provides a method for preparing a cathode material, the method comprising the following steps:

[0098] The high-entropy nickel-rich ternary precursor obtained in this embodiment is mixed with lithium hydroxide, wherein the molar ratio of lithium ions in lithium hydroxide to total metal ions in the high-entropy nickel-rich ternary precursor is 1:1. The mixture is then sintered under pure oxygen conditions to obtain a cathode material, wherein the sintering temperature is 850°C, the time is 15 h, and the heating rate is 1°C / min.

[0099] Comparative Example 1

[0100] This comparative example provides a method for preparing a ternary precursor. The preparation method is the same as in Example 1 except that seed doping solution is not introduced in step (2) and growth doping solution is not introduced in step (3).

[0101] This comparative example also provides a method for preparing a cathode material, which is the same as that in Example 1 except that it uses the ternary precursor described in this comparative example.

[0102] The SEM image of the cathode material obtained in this comparative example is shown below. Figure 2 As shown.

[0103] Comparative Example 2

[0104] This comparative example provides a method for preparing a ternary precursor. The preparation method is the same as in Example 1 except that steps (2) and (3) are not performed, and step (4) is performed according to conventional methods after step (1).

[0105] The conventional method involves step (4) as follows: using 20 kg of pure water, ammonia, precipitant solution, and dispersant (specifically polyethylene glycol) as the reaction base liquid, under a protective atmosphere, controlling the reaction temperature at 50°C, the pH of the base liquid at 12, the total ammonia at 6 g / L, the rotation speed at 600 r / min, and the concentration of the dispersant at 0.3 g / L. After ventilating for 2 hours, the mixed metal source solution, precipitant solution, complexing agent solution, seed doping solution, and growth doping solution are separately added to the reactor to start the reaction. During the reaction process, the pH is controlled at 10, and the total ammonia is controlled at 6 g / L. L, the rotation speed is controlled at 600 r / min, and the feed flow rates of the seed doping solution and the growth doping solution are both 0.2% of the volume flow rate of the ternary solution; the slurry reaching the overflow level of the reactor flows out along the overflow pipe until the precursor particle size in the reactor reaches the target particle size of 10 μm. The slurry in the reactor is collected and aged for 8 hours, the aging temperature is controlled at 60℃, the pH is controlled at 11, the total alkali concentration is 40 g / L, and the rotation speed is 300 r / min; after aging, it is washed with alkali 4 times and washed with water 4 times; finally, it is dried at a low temperature of 120℃ to obtain the ternary precursor.

[0106] This comparative example also provides a method for preparing a cathode material, which is the same as that in Example 1 except that it uses the ternary precursor described in this comparative example.

[0107] The SEM image of the cathode material obtained in this comparative example is shown below. Figure 3 As shown, by Figure 3 It can be seen that the particle size distribution range of the material is relatively narrow.

[0108] Comparative Example 3

[0109] This comparative example provides a method for preparing a ternary precursor. Except for step (2), after the reaction is completed, the reaction slurry is not washed with pure water, filtered, compacted and pulped once, i.e., the seed slurry preparation step (3) is not carried out. In step (4), the seed slurry is not introduced. Instead, the seed doping solution is replaced with the growth doping solution to continue the reaction in step (4) until the target particle size D50 is reached. The rest is the same as in Example 1.

[0110] This comparative example also provides a method for preparing a cathode material, which is the same as that in Example 1 except that it uses the ternary precursor described in this comparative example.

[0111] The Rietveld refinement results of the cathode materials obtained in the above examples and comparative examples are shown in Table 1, where a and c are unit cell parameters. The cathode materials obtained in the above examples and comparative examples were mixed with conductive carbon, polyvinylidene fluoride, and N-methylpyrrolidone at a mass ratio of 90:5:5 to obtain a cathode active layer slurry with a fineness of 10 μm and a viscosity of 500 mPa·s. After sieving, the slurry was coated on the surface of the current collector aluminum foil, and then dried, rolled, and formed into a cathode sheet. The cathode sheet was assembled with lithium foil, cellulose separator, and lithium hexafluorophosphate electrolyte to form a coin cell. The electrochemical performance of the battery was tested under the following conditions: three cycles of activation at 0.1C, 0.2C, and 0.5C, followed by 50 cycles at 1C, with a voltage of 2.7-4.3V. The electrochemical performance test results and the compaction density of the cathode material are shown in Table 2.

[0112] Table 1

[0113]

[0114] Table 2

[0115]

[0116] As can be seen from Table 1 above:

[0117] As shown in Example 1 and Comparative Example 1, if the ternary precursor is not doped, the 0.2C charge-discharge specific capacity and cycle capacity retention rate of Comparative Example 1 are both lower than those of Example 1. As shown in Example 1 and Comparative Examples 2-3, the precursors obtained by the conventional preparation method in Comparative Examples 2-3 have more uniform particle size, and there are no small particles filling the gaps between large particles, which leads to a decrease in compaction density and ultimately a decrease in charge-discharge specific capacity. As shown in Example 1 and Examples 4-6, the present invention preferably uses Mg, Zn and Ga as doping in the seed crystals, and preferably uses Zr, Nb and Sc as doping in the growth stage, which can promote the role of doping elements and further improve the performance of the battery. As shown in Example 1 and Examples 7-8, the maximum particle size Dmax of the product of the present invention will affect the particle size distribution range of the ternary precursor, which will affect the compaction density of the cathode material and further affect the electrochemical performance of the battery.

[0118] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a high-entropy nickel-rich ternary precursor, characterized in that, The preparation method includes the following steps: (1) The mixed metal source solution, precipitant solution, complexing agent solution and first doped source solution are passed into the first bottom liquid to carry out the first coprecipitation reaction. After the first coprecipitation reaction, the reaction slurry is washed and solid-liquid separation is performed to obtain seed crystals. The doping elements in the first doped source solution include Mg, Zn and Ga; (2) The seed crystals described in step (1) are slurried to obtain a seed crystal slurry. The mixed metal source solution, precipitant solution, complexing agent solution, second doping source solution and the seed crystal slurry are introduced into the second bottom liquid to carry out the second co-precipitation reaction to obtain the high-entropy nickel-rich ternary precursor. The second base liquid includes the seed crystals described in step (1); The doping elements in the second doped source solution include Zr, Nb, and Sc.

2. The production method according to claim 1, characterized by, Step (2) The second coprecipitation reaction is stopped when the maximum particle size Dmax of the product is 2-3 times the target particle size D50.

3. The preparation method according to claim 2, characterized in that, The target particle size D50 is 10-12 μm.

4. The method of claim 1, wherein, In step (2), when the second coprecipitation reaction reaches the target particle size D50, the feed flow rate of the seed slurry is dynamically adjusted so that the product particle size D50 is maintained at the target particle size D50. The slurry overflowing from the reaction is collected and stored in the overflow vessel and then thickened.

5. The production method according to claim 4, characterized by, The overflow vessel is kept at a temperature of 40-80℃ and a rotation speed of 200-500 r / min, and is kept under a protective atmosphere.

6. The preparation method according to claim 4, characterized in that, When the overflow material in the overflow vessel is 70-85% of the overflow vessel volume, thickening treatment is carried out.

7. The preparation method according to claim 2, characterized in that, After the reaction is stopped, the slurry in the reactor and overflow vessel of the second coprecipitation reaction is aged, washed and dried.

8. The preparation method according to claim 7, characterized in that, The aging temperature is 40-80℃, and the pH is 10-12.

9. The preparation method according to claim 7, characterized in that, The total alkali concentration of the aging system is 10-40 g / L, and the rotation speed is 200-500 r / min.

10. The method of claim 7, wherein, The washing process includes alkaline washing and water washing.

11. The preparation method according to claim 7, characterized in that, The drying temperature is 80-120℃.

12. The production method according to claim 1 or 2, characterized by, In step (2), before the second coprecipitation reaction reaches the target particle size D50, the flow rate of the seed slurry is 10-30% of the flow rate of the mixed metal source solution described in step (2).

13. The method of claim 1, wherein, The solid content of the seed slurry in step (2) is 20-100 g / L.

14. The method of claim 1, wherein, In step (2), the feed flow rate of the second doped source solution is 0.1-0.3% of the volumetric flow rate of the mixed metal source solution in step (2).

15. The method of claim 1, wherein, In step (2), the mass concentration of the dopant element in the second dopant source solution is 1-5 g / L.

16. The preparation method according to claim 1 or 2, characterized in that, In step (2), the temperature of the second coprecipitation reaction is 40-80℃, the pH is 9-11, and the rotation speed is 400-700r / min.

17. The preparation method according to claim 1, characterized in that, In step (2), the concentration of the complexing agent in the second coprecipitation reaction system is 5-8 g / L.

18. The preparation method according to claim 1, characterized in that, Step (2) The second base liquid also includes a precipitant, a complexing agent, a dispersant and pure water.

19. The preparation method according to claim 18, characterized in that... The dispersant includes polyethylene glycol and / or CTAB.

20. The preparation method according to claim 1, characterized in that, In step (2), the concentration of seed crystals in the second base solution is 50-120 g / L, the concentration of dispersant is 0.3-0.5 g / L, and the concentration of complexing agent is 5-8 g / L.

21. The preparation method according to claim 1, characterized in that, In step (2), the temperature of the second base liquid is 40-80℃, the pH is 9-11, and the rotation speed is 400-700r / min.

22. The preparation method according to claim 1 or 2, characterized in that, The seed crystal size D50 in step (1) is 30-50% of the target seed crystal size D50.

23. The preparation method according to claim 1, characterized in that, In step (1), the feed flow rate of the first doped source solution is 0.1-0.3% of the volumetric flow rate of the mixed metal source solution in step (1).

24. The preparation method according to claim 1, characterized in that, In step (1), the mass concentration of the dopant element in the first dopant source solution is 1-5 g / L.

25. The preparation method according to claim 1, characterized in that, In step (1), the temperature of the first coprecipitation reaction is 40-80℃, the pH is 9-11, the rotation speed is 400-700r / min, and the concentration of complexing agent in the system is 5-8g / L.

26. The preparation method according to claim 1 or 2, characterized in that, Step (1) The first base liquid includes a precipitant, a complexing agent, a dispersant and pure water.

27. The preparation method according to claim 1, characterized in that, Step (1) The temperature of the first base liquid is 40-80℃, the pH is 11-12, and the rotation speed is 400-700r / min.

28. The preparation method according to claim 1, characterized in that, In step (1), the concentration of the dispersant in the first base liquid is 0.3-0.5 g / L, and the concentration of the complexing agent is 5-8 g / L.

29. The preparation method according to claim 1, characterized in that, In the mixed metal source solution described in steps (1) and (2), the molar ratio of nickel ions, cobalt ions and manganese ions is x:y:(1-xy), where 0.80≤x≤0.97 and 0≤y≤0.

15.

30. The preparation method according to claim 1, characterized in that, The total concentration of the mixed metal source solution in steps (1) and (2) is 80-120 g / L.

31. The preparation method according to claim 1, characterized in that, The concentration of the precipitant solution in steps (1) and (2) is 200-500 g / L.

32. The preparation method according to claim 1, characterized in that, The precipitant solution in steps (1) and (2) includes any one or a combination of at least two of sodium hydroxide, sodium carbonate, or ammonium carbonate.

33. The preparation method according to claim 1, characterized in that, The concentration of the complexing agent solution in steps (1) and (2) is 9-15 mol / L.

34. The preparation method according to claim 1, characterized in that, The complexing agent solution described in steps (1) and (2) includes any one or a combination of at least two of ammonia, oxalic acid, citric acid, ascorbic acid, or EDTA.

35. A high-entropy nickel-rich ternary precursor, characterized in that, The high-entropy nickel-rich ternary precursor is prepared by the preparation method according to any one of claims 1-34.

36. A positive electrode material, characterized in that, The cathode material is obtained by mixing and sintering a lithium source and a high-entropy nickel-rich ternary precursor as described in claim 35.

37. A battery, characterized in that, The battery includes the positive electrode material as described in claim 36.

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