Precursor of single crystal type lithium-rich manganese-based material as well as preparation method and application of precursor

Abstract

The invention provides a precursor of a single crystal type lithium-rich manganese-based material as well as a preparation method and application thereof, the preparation method comprises the following steps: carrying out solid-liquid separation after a coprecipitation reaction for preparing a positive electrode precursor material to obtain a recovered mother solution, and taking the recovered mother solution as a reaction base solution; and introducing a mixed metal salt solution, a precipitant solution and a complexing agent solution into the reaction base solution, and carrying out a co-precipitation reaction to obtain the precursor of the single crystal type lithium-rich manganese-based material. According to the preparation method disclosed by the invention, the mother solution recovered by the coprecipitation reaction is adopted as the base solution, the precursor with sheet-shaped primary particles and rope-shaped morphology formed by crossing and stacking the primary particles can be obtained, and the precursor can be used for sintering the lithium-rich manganese-based positive electrode material with high single crystallization degree, so that the electrochemical performance of the battery can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and relates to a precursor of a single-crystalline lithium-rich manganese-based material, a preparation method thereof, and an application thereof. Background Art

[0002] The discharge specific capacity of the lithium-rich manganese-based cathode material exceeds 250 mAh / g, and the working voltage is greater than 3.50 V. It has the advantages of high specific capacity, good thermal stability, good cycling performance, wide charge-discharge voltage range, low price, and environmental friendliness, and is one of the most promising cathode materials for lithium-ion batteries. Although the lithium-rich manganese-based cathode material has a high specific capacity, there are still many problems in practical production, including obvious voltage and capacity attenuation during the cycling process.

[0003] In the prior art, the electrochemical performance of the battery is improved by preparing a single-crystalline lithium-rich manganese-based material. For example, CN108557905A discloses a lithium-rich material precursor, a preparation method thereof, a lithium-rich cathode material, a preparation method thereof, and a lithium battery. This method synthesizes a "sheet-like" morphology lithium-rich precursor by using a carbonate co-precipitation method, and uses this as a sintering starting material. During the sintering process, a flux H3BO3 or B2O3 is added, and the sintering process parameters are controlled to obtain a single-crystalline lithium-rich manganese-based cathode material, thereby improving the mechanical strength and compaction density of the microstructure of the cathode material, increasing the capacity, the first efficiency, and suppressing voltage attenuation. However, its process is complex. More importantly, the carbonate precursor has a low hardness. When it is prepared into a cathode material, it is very easy to form small and irregular fine particles during ball milling and pulverization. These fine particles come into contact with the electrolyte during the electrochemical reaction process, which will cause a series of side reactions, resulting in the attenuation of the electrochemical performance of the material.

[0004] Based on the above research, it is necessary to provide a precursor of a single-crystalline lithium-rich manganese-based material. The precursor obtained by the preparation method can be used to prepare a lithium-rich manganese-based material with a high degree of single crystallization, thereby improving the electrochemical performance of the battery. Summary of the Invention

[0005] The purpose of the present invention is to provide a precursor of a single-crystalline lithium-rich manganese-based material, a preparation method thereof, and an application thereof. The preparation method uses the mother liquor recovered by a co-precipitation reaction as the bottom liquid, and can obtain a precursor in which the primary particles are sheet-like and the primary particles are cross-stacked to form a rope-like morphology. This precursor can sinter a lithium-rich manganese-based cathode material with a high degree of single crystallization, thereby improving the electrochemical performance of the battery.

[0006] To achieve the purpose of the present invention, the following technical solutions are adopted:

[0007] In the first aspect, the present invention provides a preparation method of a precursor of a single-crystalline lithium-rich manganese-based material, and the preparation method includes the following steps:

[0008] (1) After solid-liquid separation is carried out after the coprecipitation reaction for preparing the cathode precursor material, a recycled mother liquor is obtained, and the recycled mother liquor is used as the reaction bottom liquid.

[0009] (2) A mixed metal salt solution, a precipitant solution and a complexing agent solution are introduced into the reaction bottom liquid described in step (1) to carry out a coprecipitation reaction, and a precursor of the single-crystalline lithium-rich manganese-based material is obtained.

[0010] When any method for preparing the cathode precursor of a lithium-ion battery is adopted in the present invention, the recycled mother liquor after the coprecipitation reaction is used as the reaction bottom liquid. Since the recycled mother liquor contains unreacted metal ions, residual complexing agent and residual precipitant, it can be used as the reaction bottom liquid for the coprecipitation reaction, thereby reducing the consumption of raw materials and the discharge of wastewater. And because the crystal nuclei remaining in the recycled mother liquor induce the oriented growth of the new batch of precursors through heterogeneous nucleation and epitaxial growth, the precursor obtained in the present invention is a hydroxide precursor with a rope-like morphology formed by the cross-stacking of flaky primary particles, which is easy to prepare a lithium-rich manganese-based cathode material with a high degree of single crystallization, thus being conducive to improving the electrochemical performance of the cathode material.

[0011] Preferably, the reaction bottom liquid described in step (1) includes residual metal ions, residual complexing agent and residual precipitant.

[0012] The reaction bottom liquid of the present invention includes residual metal ions, residual complexing agent and residual precipitant. Even if a solution with the same pH, the same complexing agent concentration and the same metal ion concentration as the reaction bottom liquid of the present invention is configured with water, metal salt, complexing agent and precipitant and used as the reaction bottom liquid, the precursor with the specific morphology of the present invention cannot be obtained. The reason is that the bottom liquid does not contain an inducer for guiding the oriented growth of the precursor, that is, the crystal nuclei remaining in the mother liquor.

[0013] Preferably, the pH of the reaction bottom liquid described in step (1) is 10.0 - 11.0. For example, it can be 10.0, 10.2, 10.4, 10.6, 10.8 or 11.0, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0014] When the recycled mother liquor of the present invention is used as the reaction bottom liquid, its pH is within a specific range. If the pH of the recycled mother liquor used as the reaction bottom liquid is too small, the original crystal nuclei will dissolve and cannot induce the oriented growth of the new batch of precursors. If the pH of the recycled mother liquor used as the reaction bottom liquid is too large, new crystal nuclei will randomly generate, and epitaxial growth along the surface of the original crystal nuclei cannot be achieved.

[0015] Preferably, in the reaction bottom liquid in step (1), the concentration of the residual complexing agent is 0.5 - 5 g / L. For example, it can be 0.5 g / L, 1.5 g / L, 2.5 g / L, 3.5 g / L, 4.5 g / L or 5 g / L, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0016] Preferably, in the reaction bottom liquid in step (1), the total concentration of the residual metal ions is 5 - 20 g / L. For example, it can be 5 g / L, 10 g / L, 15 / L or 20 g / L, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0017] Preferably, the residual metal ions include nickel ions, manganese ions and cobalt ions.

[0018] Preferably, in step (1), after the coprecipitation reaction for preparing the lithium-rich manganese-based cathode precursor material, solid-liquid separation is carried out to obtain the recycled mother liquor.

[0019] After any coprecipitation reaction is completed in the present invention, the mother liquor is collected by solid-liquid separation. The conditions for any coprecipitation reaction are not specifically limited. Preferably, the mother liquor is obtained by recycling after the coprecipitation reaction for preparing the lithium-rich manganese-based cathode precursor material. And preferably, the conditions for the coprecipitation reaction for preparing the lithium-rich manganese-based cathode precursor material are the same as those for the coprecipitation reaction in step (2), with the difference that the reaction bottom liquid used is a solution prepared from water, a complexing agent solution and a precipitant solution.

[0020] Preferably, the temperature of the reaction bottom liquid in step (1) is 40 - 60 °C. For example, it can be 40 °C, 45 °C, 50 °C, 55 °C or 60 °C, and the stirring speed is 300 - 700 rpm. For example, it can be 300 rpm, 400 rpm, 500 rpm, 600 rpm or 700 rpm, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0021] Preferably, the pH of the coprecipitation reaction in step (2) is between 8.5 and 10, which means that the lowest pH of the coprecipitation reaction in step (2) is above 8.5. For example, it can be 8.5, 8.7, 8.9, 9.1 or 9.3, and the lowest pH of the coprecipitation reaction in step (2) is below 10. For example, it can be 10, 9.8, 9.6 or 9.4, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0022] Preferably, the temperature of the coprecipitation reaction in step (2) is 40 - 50 °C. For example, it can be 40 °C, 42 °C, 44 °C, 46 °C, 48 °C or 50 °C, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0023] Preferably, the stirring speed for the coprecipitation reaction in step (2) is 300 - 700 rpm. For example, it can be 300 rpm, 400 rpm, 500 rpm, 600 rpm, or 700 rpm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0024] Preferably, the feeding is stopped after the coprecipitation reaction in step (2) until the particle size D50 of the product particles reaches 3 - 7 μm. For example, it can be 3 μm, 4 μm, 5 μm, 6 μm, or 7 μm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0025] Preferably, the precipitant solution in step (2) includes sodium hydroxide solution and / or potassium hydroxide solution.

[0026] Preferably, the mass fraction of the precipitant solution in step (2) is 30 - 35%. For example, it can be 30%, 31%, 32%, 33%, 34%, or 35%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0027] Preferably, the complexing agent solution in step (2) includes any one or a combination of at least two of ammonia water, oxalic acid, or EDTA.

[0028] Preferably, the mass concentration of the complexing agent solution in step (2) is 5 - 15 g / L. For example, it can be 5 g / L, 7 g / L, 9 g / L, 11 g / L, 13 g / L, or 15 g / L, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0029] Preferably, in the mixed metal salt solution of step (2), the molar ratio of nickel ions, cobalt ions, and manganese ions is x:y:z, where 0.1 ≤ x ≤ 0.4. For example, it can be 0.1, 0.2, 0.3, or 0.4; 0.1 ≤ y ≤ 0.4. For example, it can be 0.1, 0.2, 0.3, or 0.4; z ≥ 0.6. For example, it can be 0.6, 0.7, 0.8, or 0.9, and x + y + z = 1.

[0030] Preferably, the mixed metal salt solution in step (2) includes any one or a combination of at least two of sulfates, nitrates, or chlorides.

[0031] Preferably, the total metal ion concentration of the mixed metal salt solution in step (2) is 90 - 110 g / L. For example, it can be 90 g / L, 100 g / L, or 110 g / L, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0032] Preferably, after the coprecipitation reaction in step (2), solid-liquid separation, washing, and drying are carried out.

[0033] Preferably, the number of washing times is 2 - 5 times, for example, it can be 2 times, 3 times, 4 times, or 5 times.

[0034] Preferably, the washing includes first washing with an alkali solution 2 - 5 times, for example, it can be 2 times, 3 times, 4 times, or 5 times, and then washing with hot water 2 - 5 times, for example, it can be 2 times, 3 times, 4 times, or 5 times.

[0035] Preferably, the drying temperature is 100 - 150 °C, for example, it can be 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, or 150 °C, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0036] In a second aspect, the present invention provides a precursor of a single-crystalline lithium-rich manganese-based material, and the precursor of the single-crystalline lithium-rich manganese-based material is prepared by using the preparation method as described in the first aspect;

[0037] The primary particles of the precursor of the single-crystalline lithium-rich manganese-based material are flaky, and the flaky primary particles are cross-stacked into a rope-like morphology.

[0038] Preferably, the length of the primary particles is 200 - 800 nm, for example, it can be 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, or 800 nm, and the thickness is 10 - 80 nm, for example, it can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, or 80 nm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0039] In a third aspect, the present invention provides a single-crystalline lithium-rich manganese-based material, and the single-crystalline lithium-rich manganese-based material is prepared from a lithium source and the precursor of the single-crystalline lithium-rich manganese-based material as described in the second aspect.

[0040] In a fourth aspect, the present invention provides a lithium-ion battery, and the lithium-ion battery includes the single-crystalline lithium-rich manganese-based material as described in the third aspect.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] When preparing the cathode precursor of a lithium-ion battery according to the present invention, the recycled mother liquor after the coprecipitation reaction is used as the reaction bottom liquid. Since the recycled mother liquor contains unreacted metal ions, complexing agents, and precipitant residues, it can be used as the reaction bottom liquid for the coprecipitation reaction, thereby reducing the consumption of raw materials and the discharge of wastewater. Moreover, the precursor obtained in the present invention is a hydroxide precursor with a rope-like morphology formed by the cross-stacking of flaky primary particles, which is easy to prepare a lithium-rich manganese-based cathode material with a high degree of single crystallization, thus facilitating the improvement of the electrochemical performance of the lithium-rich manganese-based cathode material. Description of the Drawings

[0043] Figure 1 It is a morphology diagram of the precursor obtained in Example 1 of the present invention.

[0044] Figure 2 It is a morphology diagram of the cathode material prepared from the precursor obtained in Example 1 of the present invention. Detailed Embodiments

[0045] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0046] Comparative Example 1

[0047] This comparative example provides a method for preparing a lithium-rich manganese-based precursor, and the preparation method includes the following steps:

[0048] (1) Using pure water, sodium hydroxide, and ammonia water to prepare a reaction bottom liquid by mixing, and adding the reaction bottom liquid into a 100L reaction kettle. The pH of the reaction bottom liquid is 10.5, and the ammonia concentration is 4g / L;

[0049] (2) Simultaneously injecting a nickel-cobalt-manganese ternary solution with a mass concentration of 95g / L (the molar ratio of Ni ions, Co ions, and manganese ions is 0.35:0.05:0.60), a 30% sodium hydroxide solution, and 5g / L of ammonia water into the reaction kettle containing the reaction bottom liquid through a metering pump. Set the stirring speed of the reaction kettle to 600rpm, control the reaction temperature at 55°C, and control the pH between 9.0 - 10.0 for coprecipitation reaction;

[0050] (3) When the median particle size D50 of the precursor particles reaches 4.0μm, stop feeding;

[0051] (4) Transfer the slurry after the reaction to a suction filter flask, and wash it three times with alkali solution and pure water respectively;

[0052] (5) Transfer the solid material obtained by suction filtration and washing to an oven, dry it at 100°C, and finally obtain the lithium-rich manganese-based precursor.

[0053] Comparative Example 2

[0054] This comparative example provides a method for preparing a lithium-rich manganese-based precursor, and the preparation method includes the following steps:

[0055] (1) Using pure water, nickel-cobalt-manganese ternary solution, sodium hydroxide and ammonia water to mix and prepare a reaction bottom liquid, adding the reaction bottom liquid into a 100 L reaction kettle, the pH of the reaction bottom liquid is 10.5, the ammonia concentration is 4 g / L, and the total metal ion concentration is 10 g / L;

[0056] (2) Simultaneously injecting a nickel-cobalt-manganese ternary solution with a mass concentration of 95 g / L (the molar ratio of Ni ions, Co ions and Mn ions is 0.35:0.05:0.60), 30% sodium hydroxide solution and 5 g / L ammonia water into the reaction kettle containing the reaction bottom liquid through a metering pump, setting the stirring speed of the reaction kettle to 600 rpm, controlling the reaction temperature to 55 °C, and controlling the pH between 9.0 - 10.0 to carry out a coprecipitation reaction;

[0057] (3) When the median particle size D50 of the precursor particles reaches 4.0 μm, stop feeding;

[0058] (4) Transfer the slurry after the reaction to a suction filter flask, and wash it three times with alkali solution and pure water respectively;

[0059] (5) Transfer the solid material obtained by suction filtration and washing to an oven, dry it at 100 °C, and finally obtain the lithium-rich manganese-based precursor.

[0060] Example 1

[0061] This example provides a method for preparing a precursor of a single-crystalline lithium-rich manganese-based material, and the preparation method includes the following steps:

[0062] (1) Using the mother liquor obtained by suction filtration after the coprecipitation reaction carried out by the same method as in Comparative Example 1 as the reaction bottom liquid, adding it into a 100 L reaction kettle, and controlling the pH of the reaction bottom liquid to 10.5, the ammonia concentration to 4 g / L, and the residual total metal ion concentration to 10 g / L by controlling the conditions of the coprecipitation reaction;

[0063] (2) Simultaneously injecting a nickel-cobalt-manganese ternary solution with a mass concentration of 95 g / L (the molar ratio of Ni ions, Co ions and Mn ions is 0.35:0.05:0.60), 30% sodium hydroxide solution and 5 g / L ammonia water into the reaction kettle containing the reaction bottom liquid through a metering pump, setting the stirring speed of the reaction kettle to 600 rpm, controlling the reaction temperature to 55 °C, and controlling the pH between 9.0 - 10.0 to carry out a coprecipitation reaction;

[0064] (3) When the median particle size D50 of the precursor particles reaches 4.0 μm, stop feeding;

[0065] (4) Transfer the slurry after the reaction to a suction flask and wash it three times with alkali solution and pure water respectively.

[0066] (5) Transfer the solid material obtained by suction filtration and washing to an oven and dry it at 100 °C to finally obtain the precursor of the single-crystalline lithium-rich manganese-based material.

[0067] The precursor obtained in this example is as Figure 1 shown. It can be seen from Figure 1 that the primary particles of the precursor are flaky, and the flaky primary particles cross-stack into a rope-like morphology.

[0068] Example 2

[0069] This example provides a method for preparing a precursor of a single-crystalline lithium-rich manganese-based material. The preparation method includes the following steps:

[0070] (1) Use the mother liquor obtained by suction filtration after the coprecipitation reaction in the same method as in Comparative Example 1 as the reaction bottom liquid, add it to a 100 L reaction kettle, and control the pH of the reaction bottom liquid to 10.0, the ammonia concentration to 5 g / L, and the residual total metal ion concentration to 20 g / L by controlling the conditions of the coprecipitation reaction.

[0071] (2) Simultaneously inject a nickel-cobalt-manganese ternary solution with a mass concentration of 100 g / L (the molar ratio of Ni ions, Co ions and manganese ions is 0.30:0.05:0.65), a 32% sodium hydroxide solution and an 8 g / L EDTA solution into the reaction kettle containing the reaction bottom liquid through a metering pump. Set the stirring speed of the reaction kettle to 500 rpm, control the reaction temperature to 56 °C, and control the pH between 8.5 - 9.5 to carry out the coprecipitation reaction.

[0072] (3) When the median particle size D50 of the precursor particles reaches 5.0 μm, stop feeding.

[0073] (4) Transfer the slurry after the reaction to a suction flask and wash it three times with alkali solution and pure water respectively.

[0074] (5) Transfer the solid material obtained by suction filtration and washing to an oven and dry it at 100 °C to finally obtain the precursor of the single-crystalline lithium-rich manganese-based material.

[0075] Example 3

[0076] This example provides a method for preparing a precursor of a single-crystalline lithium-rich manganese-based material. The preparation method includes the following steps:

[0077] (1) After the coprecipitation reaction was carried out in the same manner as in Comparative Example 1, the mother liquor obtained by suction filtration was used as the reaction bottom liquid and added to a 100 L reaction kettle. By controlling the conditions of the coprecipitation reaction, the pH of the reaction bottom liquid was 11.0, the ammonia concentration was 3 g / L, and the residual total metal ion concentration was 5 g / L;

[0078] (2) A nickel-cobalt-manganese ternary solution with a mass concentration of 110 g / L (the molar ratio of Ni ions, Co ions, and Mn ions was 0.30:0.05:0.65), a 35% sodium hydroxide solution, and 15 g / L ammonia water were simultaneously injected into the reaction kettle containing the reaction bottom liquid through a metering pump. The stirring speed of the reaction kettle was set to 700 rpm, the reaction temperature was controlled at 60 °C, and the pH was controlled between 8.5 - 9.5 for the coprecipitation reaction;

[0079] (3) When the median particle size D50 of the precursor particles reached 7.0 μm, the feeding was stopped;

[0080] (4) The slurry after the reaction was transferred to a suction filtration flask and washed five times with alkali solution and pure water respectively;

[0081] (5) The solid material obtained by suction filtration and washing was transferred to an oven and dried at 150 °C to finally obtain the precursor of the single-crystalline lithium-rich manganese-based material.

[0082] Example 4

[0083] This example provides a method for preparing a precursor of a single-crystalline lithium-rich manganese-based material. Except that the pH of the reaction bottom liquid in step (1) was 9.5, the rest were the same as in Example 1.

[0084] Example 5

[0085] This example provides a method for preparing a precursor of a single-crystalline lithium-rich manganese-based material. Except that the pH of the reaction bottom liquid in step (1) was 11.5, the rest were the same as in Example 1.

[0086] Example 6

[0087] This example provides a method for preparing a precursor of a single-crystalline lithium-rich manganese-based material. Except that the residual total metal ion concentration of the reaction bottom liquid in step (1) was 3 g / L, the rest were the same as in Example 1.

[0088] Example 7

[0089] This example provides a method for preparing a precursor of a single-crystalline lithium-rich manganese-based material. Except that the residual total metal ion concentration of the reaction bottom liquid in step (1) was 23 g / L, the rest were the same as in Example 1.

[0090] The precursors obtained from the above examples and comparative examples were mixed with lithium hydroxide and sintered at 900 °C for 10 h to obtain a lithium-rich manganese-based cathode material (wherein, the morphology diagram of the cathode material prepared from the precursor of Example 1 is as shown in Figure 2 shown, and it can be seen from Figure 2 that the material is a single-crystalline material); the prepared lithium-rich manganese-based cathode material, polyvinylidene fluoride, and Super P were added to N-methylpyrrolidone at a mass ratio of 80:5:5 and stirred into a cathode slurry, and then the cathode slurry was evenly coated on the cathode current collector aluminum foil, and after drying and rolling, a cathode electrode sheet was obtained; a lithium sheet, a separator, an electrolyte (the electrolyte is a 5V high-voltage electrolyte), and the above-obtained cathode electrode sheet were assembled in sequence, and the battery model was a 2032-type battery case to obtain a lithium-ion button battery.

[0091] The obtained lithium-ion button battery was tested for specific capacity and cycle capacity retention rate at 25 °C under the charge-discharge regime of 0.1C (1C = 250 mAh / g) and the charge-discharge conditions with a voltage range of 2.0 to 4.6V. The test results are shown in Table 1:

[0092] Table 1

[0093]

[0094] It can be seen from Table 1 that:

[0095] From Example 1 and Comparative Example 1, it can be seen that the mother liquor obtained after solid-liquid separation by the coprecipitation reaction in the present invention is used as the reaction bottom liquid, and a precursor with a rope-like morphology formed by the cross-stacking of flaky primary particles can be obtained, so that a single-crystalline cathode material can be prepared, improving the electrochemical performance of the battery; from Example 1 and Comparative Example 2, it can be seen that even if pure water, a nickel-cobalt-manganese ternary solution, sodium hydroxide, and ammonia water are mixed to prepare the reaction bottom liquid, the precursor with the specific morphology of the present invention cannot be prepared, and the electrochemical performance of the obtained battery decreases compared with Example 1; from Example 1 and Examples 4-7, it can be seen that the pH and residual total metal ion concentration of the recycled mother liquor used as the reaction bottom liquid in the present invention are preferably within a specific range, so as to ensure the morphology of the precursor, improve the single-crystalline degree of the cathode material, and improve the performance of the battery.

[0096] The above is only the specific implementation manner 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 thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a precursor of a single-crystalline lithium-rich manganese-based material, characterized in that, The preparation method includes the following steps: (1) After the co-precipitation reaction for preparing the cathode precursor material, solid-liquid separation is carried out to obtain a recycled mother liquor, and the recycled mother liquor is used as the reaction bottom liquid; (2) A mixed metal salt solution, a precipitant solution, and a complexing agent solution are introduced into the reaction bottom liquid described in step (1) to carry out a co-precipitation reaction to obtain a precursor of the single-crystalline lithium-rich manganese-based material.

2. The preparation method according to claim 1, wherein, The reaction bottom liquid in step (1) includes residual metal ions, residual complexing agent, and residual precipitant; Preferably, the pH of the reaction bottom liquid in step (1) is 10.0 - 11.

0.

3. The preparation method according to claim 2, characterized in that, In the reaction bottom liquid of step (1), the concentration of the residual complexing agent is 0.5 - 5 g / L; Preferably, in the reaction bottom liquid of step (1), the total concentration of the residual metal ions is 5 - 20 g / L; Preferably, the residual metal ions include nickel ions, manganese ions, and cobalt ions.

4. The preparation method according to any one of claims 1-3, characterized in that, In step (1), after the co-precipitation reaction for preparing the lithium-rich manganese-based cathode precursor material, solid-liquid separation is carried out to obtain a recycled mother liquor; Preferably, the temperature of the reaction bottom liquid in step (1) is 40 - 60 °C, and the stirring speed is 300 - 700 rpm.

5. The preparation method according to any one of claims 1-4, characterized in that, The pH of the co-precipitation reaction in step (2) is between 8.5 and 10; Preferably, the temperature of the co-precipitation reaction in step (2) is 40 - 50 °C; Preferably, the stirring speed of the co-precipitation reaction in step (2) is 300 - 700 rpm; Preferably, in step (2), the co-precipitation reaction is stopped after the product particle size D50 reaches 3 - 7 μm.

6. The preparation method according to any one of claims 1-5, characterized in that, The precipitant solution in step (2) includes sodium hydroxide solution and / or potassium hydroxide solution; Preferably, the mass fraction of the precipitant solution in step (2) is 30 - 35%; Preferably, the complexing agent solution in step (2) includes any one or a combination of at least two of ammonia water, oxalic acid, or EDTA; Preferably, the mass concentration of the complexing agent solution in step (2) is 5 - 15 g / L.

7. The preparation method according to any one of claims 1-5, characterized in that, In the mixed metal salt solution of step (2), the molar ratio of nickel ions, cobalt ions, and manganese ions is x:y:z, where 0.1 ≤ x ≤ 0.4, 0.1 ≤ y ≤ 0.4, z ≥ 0.6, and x + y + z = 1; Preferably, the total metal ion concentration of the mixed metal salt solution in step (2) is 90 - 110 g / L; Preferably, after the co-precipitation reaction in step (2), solid-liquid separation, washing, and drying are carried out; Preferably, the number of washing times is 2 - 5 times; Preferably, the washing includes first washing with an alkali solution and then washing with hot water; Preferably, the drying temperature is 100 - 150 °C.

8. A precursor of a single-crystalline lithium-rich manganese-based material, characterized in that, The precursor of the single-crystalline lithium-rich manganese-based material is prepared by the preparation method described in any one of claims 1 - 7; The primary particles of the precursor of the single-crystalline lithium-rich manganese-based material are flaky, and the flaky primary particles are cross-stacked into a rope-like morphology; Preferably, the length of the primary particles is 200 - 800 nm, and the thickness is 10 - 80 nm.

9. A single-crystalline lithium-rich manganese-based material, characterized in that, The single-crystalline lithium-rich manganese-based material is prepared from a lithium source and the precursor of the single-crystalline lithium-rich manganese-based material described in claim 8.

10. A lithium-ion battery, characterized in that, The lithium-ion battery includes the single-crystalline lithium-rich manganese-based material as described in Claim 9.

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