Lithium-rich manganese-based precursor material, and preparation method therefor and use thereof

Abstract

Provided in the present application are a lithium-rich manganese-based precursor material, and a preparation method therefor and the use thereof. The preparation method comprises the following steps: in a protective gas atmosphere, mixing a nickel-cobalt-manganese mixed salt solution, a precipitator solution and a complexing agent solution, subjecting same to a co-precipitation reaction until particles enter a growth stage, starting the introduction of an oxygen-containing gas, and then continuously subjecting same to the co-precipitation reaction, so as to obtain a lithium-rich manganese-based precursor material. In the preparation method of the present application, by introducing the oxidizing atmosphere in the growth stage of the precursor material, the problems of compact particle growth, being prone to agglomerating and poor morphology in the existing preparation process for a lithium-rich manganese precursor material are solved, and a lithium-rich manganese-based precursor material having high dispersity and a high specific surface area is obtained.

Description

A lithium-rich manganese-based precursor material and its preparation method and application Technical Field

[0001] The present application belongs to the technical field of battery materials and relates to a lithium-rich manganese-based precursor material and a preparation method and application thereof. Background Art

[0002] In recent years, lithium-ion batteries have achieved great commercial success in the field of portable electronic products and are also the main energy storage device for electric vehicles. Lithium-rich manganese-based cathode materials have high specific capacity (>250mAh·g -1 ) and low cost, and is considered to be a cathode material with good application prospects. It is well known that the quality of the precursor material is crucial to the performance of lithium-rich manganese-based cathode materials.

[0003] The current industrial preparation of lithium-rich manganese precursors mostly adopts the hydroxide co-precipitation method. Specifically, a nickel-cobalt-manganese mixed salt solution, a hydroxide precipitant and a complexing agent are mixed and placed into a reactor with a base liquid and a protective gas for constant temperature co-precipitation. After the reaction, the overflow is subjected to solid-liquid separation, aging, centrifugation and drying to obtain a spherical lithium-rich manganese precursor material. However, as the manganese content increases, the agglomeration of small-particle nickel-cobalt-manganese hydroxide becomes serious and the morphological uniformity deteriorates, resulting in a deterioration in the specific surface area and physical and chemical properties of the precursor.

[0004] For example, CN 110323430A discloses a method for preparing a lithium-rich manganese-based material and a lithium-rich manganese-based material. The preparation method comprises: 2+ and M 2+ A mixed metal salt solution, a complexing agent, a precipitant and a reducing agent are mixed to prepare a lithium-rich manganese precursor. By controlling the concentration of the reducing agent, a lithium-rich manganese-based material with better electrochemical performance is prepared. However, during the co-precipitation process of the lithium-rich manganese-based precursor, as the manganese content increases, the particles grow more densely and agglomerate severely. The overall morphology of the precursor is difficult to control, and the sphericity and dispersibility are poor, resulting in an unstable structure of the positive electrode material sintered subsequently and poor cycle performance.

[0005] For example, CN 116216796A discloses a modified nickel-manganese binary precursor, its preparation method, and application. In this preparation method, a modifier is added to the reaction base liquid in advance to control the crystal form of the binary nickel-manganese precursor. The obtained nickel-manganese hydroxide primary crystal form is relatively dense. Although this avoids the problem of easy precipitation of manganese tetraoxide and loose morphology in the primary crystal form in the existing nickel-manganese binary precursor preparation method, as the manganese content increases during the co-precipitation of the lithium-rich manganese-based precursor, the particles grow more densely and agglomerate severely. The overall morphology of the precursor obtained by this preparation method is difficult to control, and the sphericity and dispersibility are poor, which is not conducive to the subsequent sintering of the positive electrode material.

[0006] Based on the above research, it is necessary to provide a method for preparing a lithium-rich manganese-based precursor material, which can solve the problems of particle agglomeration, poor dispersibility and difficult morphology control due to increased manganese content during co-precipitation.

[0007] Summary of the Invention

[0008] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0009] The purpose of the present application is to provide a lithium-rich manganese-based precursor material and its preparation method and application. The preparation method avoids the problems of dense particle growth, easy agglomeration and poor morphology in the existing preparation process of lithium-rich manganese precursor materials by introducing an oxidizing atmosphere during the growth stage of the precursor material, thereby obtaining a lithium-rich manganese-based precursor material with high dispersibility and high specific surface area.

[0010] To achieve this goal, this application adopts the following technical solutions:

[0011] In a first aspect, the present application provides a method for preparing a lithium-rich manganese-based precursor material, the preparation method comprising the following steps:

[0012] Under a protective gas atmosphere, a nickel-cobalt-manganese mixed salt solution, a precipitant solution and a complexing agent solution are mixed to carry out a coprecipitation reaction. When the coprecipitation reaction reaches the particle growth stage, oxygen-containing gas is introduced, and then the coprecipitation reaction is continued to obtain the lithium-rich manganese-based precursor material.

[0013] In order to avoid the problem of particle agglomeration due to the increase of manganese content when preparing lithium-rich manganese-based precursors by co-precipitation, the present application conducts co-precipitation in a protective gas atmosphere. When the particles enter the growth stage after nucleation, oxygen-containing gas is introduced to slightly oxidize the system, so that the particles grow in the protective gas and oxygen-containing gas (the protective gas is always introduced during the co-precipitation reaction stage of the present application), thereby avoiding particle agglomeration. In addition, the preparation method of the present application is simple and low-cost. It only requires adding a three-way joint at the air inlet on the basis of the original co-precipitation to introduce oxygen atmosphere, and there is no need to modify or add an air inlet pipe to the existing kettle.

[0014] In one embodiment, the oxygen-containing gas is introduced after the coprecipitation reaction has lasted for 2-10 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours.

[0015] In the present application, the oxygen-containing gas is introduced when the co-precipitation reaction reaches a specific time. If the oxygen-containing gas is introduced too late, the lithium-rich manganese precursor will have particles that grow closely, adhere to each other, and agglomerate severely in the early growth stage, and it will be difficult to improve its dispersion in the later stage; if the oxygen-containing gas is introduced too early, the precursor will be easily oxidized in the early nucleation stage, and MnO2 will easily precipitate in the primary crystal form, resulting in uneven precursor components.

[0016] In one embodiment, the oxygen-containing gas comprises air or oxygen, and may be air.

[0017] The oxygen-containing gas introduced in the present application can be air. If it is pure oxygen gas, the oxygen content of the system will be too high, which will also affect the particle dispersibility and specific surface area.

[0018] In one embodiment, the protective gas comprises nitrogen and / or an inert gas.

[0019] In one embodiment, the flow rate of the oxygen-containing gas is 5-15 L / h, for example, 5 L / h, 7 L / h, 9 L / h, 11 L / h, 13 L / h or 15 L / h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] The flow rate of the oxygen-containing gas introduced in this application will affect the degree of oxidation of the system. If the flow rate of the oxygen-containing gas introduced is too small, the degree of oxidation introduced into the system will be insufficient, resulting in severe agglomeration of the precursor particles and poor dispersion improvement effect. If the flow rate of the oxygen-containing gas introduced is too large, excessive oxidation will occur, resulting in the generation of a small amount of impurities such as Mn3O4 and MnO2, which is not conducive to improving the dispersion of the particles. In addition, if the gas flow rate is too large, the production cost will be increased.

[0021] In one embodiment, the flow rate of the protective gas is 50-200 L / h, for example, 50 L / h, 75 L / h, 100 L / h, 125 L / h, 150 L / h, 175 L / h or 200 L / h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0022] Similarly, the flow rate of the protective gas in this application will also affect the oxygen content in the system.

[0023] In one embodiment, the precipitant solution comprises sodium hydroxide solution and / or potassium hydroxide solution.

[0024] In one embodiment, the mass fraction of the precipitant solution is 30-35wt%, for example, it can be 30wt%, 31wt%, 32wt%, 33wt%, 34wt% or 35wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] In one embodiment, the complexing agent solution includes oxalic acid and / or ammonia water.

[0026] In one embodiment, the mass concentration of the complexing agent solution is 2-10 g / L, for example, 2 g / L, 5 g / L, 8 g / L or 10 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] In one embodiment, the nickel-cobalt-manganese mixed salt solution, the precipitant solution and the complexing agent solution are simultaneously introduced into the base solution to perform a co-precipitation reaction.

[0028] In one embodiment, the pH of the base solution is 11.5-12, for example, 11.5, 11.75 or 12, and the base solution comprises water, a precipitant solution and a complexing agent solution.

[0029] In one embodiment, the nickel-cobalt-manganese mixed salt solution includes any one of sulfate, nitrate or chloride, or a combination of at least two of them.

[0030] In one embodiment, in the nickel-cobalt-manganese mixed salt solution, the molar ratio of nickel ions, cobalt ions and manganese ions is x:y:z, wherein x+y+z=1, z≥0.6, for example, it can be 0.6, 0.7, 0.8 or 0.9, 0<x<0.4, for example, it can be 0.1, 0.2 or 0.3, 0<y<0.4, for example, it can be 0.1, 0.2 or 0.3, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] In one embodiment, the mass concentration of the nickel-cobalt-manganese mixed salt solution 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, and other unlisted values ​​within the numerical range are also applicable.

[0032] In one embodiment, the coprecipitation reaction temperature is 50-60°C, for example, 50°C, 55°C or 60°C, the pH is 9.5-11.5, for example, 9.5, 10, 11 or 11.5, and the stirring speed is 400-700rpm, for example, 400rpm, 500rpm, 600rpm or 700rpm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] In one embodiment, after the coprecipitation reaction is completed, filtration, washing and drying are further performed.

[0034] In one embodiment, the drying temperature is 100-150°C, for example, 100°C, 120°C, 140°C or 150°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0035] In one embodiment, the washing comprises washing with alkaline solution and water 2-5 times, for example, 2 times, 3 times, 4 times or 5 times.

[0036] The water used for washing in this application is hot water.

[0037] As an optional technical solution of the preparation method described in this application, the preparation method comprises the following steps:

[0038] Under a protective gas atmosphere, a nickel-cobalt-manganese mixed salt solution, a precipitant solution, and a complexing agent solution are simultaneously introduced into the base liquid to carry out a coprecipitation reaction. After the coprecipitation reaction has been carried out for 2-10 hours, an oxygen-containing gas is introduced, and then the coprecipitation reaction is continued. After the coprecipitation reaction is completed, suction filtration, washing, and drying at a temperature of 100-150° C. are carried out to obtain the lithium-rich manganese-based precursor material;

[0039] The oxygen-containing gas includes air or oxygen, and the flow rate of the oxygen-containing gas is 5-15 L / h; the protective gas includes nitrogen and / or inert gas, and the flow rate of the protective gas is 50-200 L / h; the temperature of the coprecipitation reaction is 50-60°C, the pH is 9.5-11.5, and the stirring speed is 400-700 rpm;

[0040] The pH of the base solution is 11.5-12, and the base solution includes water, a precipitant solution, and a complexing agent solution. In the nickel-cobalt-manganese mixed salt solution, the molar ratio of nickel ions, cobalt ions, and manganese ions is x:y:z, wherein x+y+z=1, z≥0.6, 0<x<0.4, and 0<y<0.4.

[0041] In a second aspect, the present application provides a lithium-rich manganese-based precursor material as described in the first aspect, wherein the lithium-rich manganese-based precursor material is prepared using the preparation method described in the first aspect.

[0042] In a third aspect, the present application provides a lithium-rich manganese-based positive electrode material, which is obtained by mixing and sintering the lithium-rich manganese-based precursor material as described in the second aspect with a lithium source.

[0043] In a fourth aspect, the present application provides a battery comprising the lithium-rich manganese-based positive electrode material as described in the third aspect.

[0044] Compared with the prior art, this application has the following beneficial effects:

[0045] (1) The present invention introduces micro-oxidation during the precursor growth stage, and only requires adding a three-way joint at the air inlet to introduce an oxygen-containing atmosphere. There is no need to modify or add an air inlet pipe to the existing kettle body, which simplifies the preparation process and can reduce production costs.

[0046] (2) The present invention micro-oxidizes the particles during the precursor growth stage, effectively avoiding the defects of particle agglomeration and poor dispersion of the current lithium-rich manganese precursor during the reaction stage, and obtains a highly dispersed lithium-rich manganese-based precursor with uniformly distributed particles and a specific surface area maintained at 25-30m 2 / g, and the precursor with uniform particle distribution and high specific surface area is beneficial to the structural stability and cycle performance improvement of the subsequent positive electrode material.

[0047] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0049] FIG1 is a SEM image of the lithium-rich manganese-based precursor material obtained in Example 1 of the present application at a magnification of 3000 times;

[0050] FIG2 is a SEM image of the lithium-rich manganese-based precursor material obtained in Example 1 of the present application at a magnification of 5000 times;

[0051] FIG3 is a SEM image of the lithium-rich manganese-based precursor material obtained in Comparative Example 1 of the present application at a magnification of 3000 times;

[0052] FIG4 is a SEM image of the lithium-rich manganese-based precursor material obtained in Comparative Example 1 of the present application at a magnification of 5000 times. DETAILED DESCRIPTION

[0053] The technical solution of the present application is further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations of the present application.

[0054] Example 1

[0055] This embodiment provides a method for preparing a lithium-rich manganese-based precursor material, the preparation method comprising the following steps:

[0056] (1) Add 33.5 kg of pure water, 150 g of sodium hydroxide solution, and 200 g of oxalic acid solution to the reactor as the reaction base liquid, and introduce nitrogen for 3 hours at a nitrogen flow rate of 200 L / h. Control the initial pH value of the base liquid between 11.6 and 11.8;

[0057] (2) Under a nitrogen atmosphere, a nickel-cobalt-manganese mixed salt solution at a flow rate of 1.5 kg / h, a sodium hydroxide solution at a flow rate of 0.69 kg / h, and an oxalic acid solution at a flow rate of 0.18 kg / h are introduced into the bottom liquid of step (1) in parallel to carry out a coprecipitation reaction. After the coprecipitation reaction is continued for 6 hours, oxygen-containing gas is introduced, and then the coprecipitation reaction is continued. After the coprecipitation reaction is completed, the slurry after the reaction is completed is transferred to a suction filtration bottle, washed three times with alkali solution and hot water respectively, and then dried at 120° C. to obtain the lithium-rich manganese-based precursor material;

[0058] The oxygen-containing gas is air, and the flow rate of the oxygen-containing gas is 8 L / h; the flow rate of the nitrogen is 200 L / h; the temperature of the coprecipitation reaction is 58°C, the pH is controlled between 10.4-10.6, and the stirring speed is 600 rpm;

[0059] The nickel-cobalt-manganese mixed salt solution has a mass concentration of 100 g / L, and a molar ratio of nickel ions, cobalt ions, and manganese ions of 0.167:0.167:0.666; the mass fraction of the sodium hydroxide solution is 32%, and the concentration of oxalic acid is 5 g / L;

[0060] The SEM image of the lithium-rich manganese-based precursor material obtained in this example at a magnification of 3000 times is shown in FIG1 , and the SEM image at a magnification of 5000 times is shown in FIG2 .

[0061] Example 2

[0062] This embodiment provides a method for preparing a lithium-rich manganese-based precursor material, the preparation method comprising the following steps:

[0063] (1) Add 33.5 kg of pure water, 200 g of sodium hydroxide solution, and 250 g of oxalic acid solution to the reactor as the reaction base liquid, and introduce nitrogen for 3 hours at a nitrogen flow rate of 200 L / h. The initial pH value of the base liquid is controlled to be 12;

[0064] (2) Under a nitrogen atmosphere, a nickel-cobalt-manganese mixed salt solution at a flow rate of 1.5 kg / h, a sodium hydroxide solution at a flow rate of 0.69 kg / h, and an oxalic acid solution at a flow rate of 0.18 kg / h are introduced into the bottom liquid of step (1) in parallel to carry out a coprecipitation reaction. After the coprecipitation reaction is carried out for 2 hours, oxygen-containing gas is introduced, and then the coprecipitation reaction is continued. After the coprecipitation reaction is completed, the slurry after the reaction is completed is transferred to a suction filtration bottle, washed three times with alkaline solution and hot water respectively, and then dried at a temperature of 120° C. to obtain the lithium-rich manganese-based precursor material;

[0065] The oxygen-containing gas is air, and the flow rate of the oxygen-containing gas is 15 L / h; the flow rate of the nitrogen is 200 L / h; the temperature of the coprecipitation reaction is 50°C, the pH is controlled between 10.0-10.4, and the stirring speed is 400 rpm;

[0066] The mass concentration of the nickel-cobalt-manganese mixed salt solution is 80 g / L, and the molar ratio of nickel ions, cobalt ions, and manganese ions is 0.167:0.167:0.666; the mass fraction of the sodium hydroxide solution is 30%, and the concentration of oxalic acid is 2 g / L.

[0067] Example 3

[0068] This embodiment provides a method for preparing a lithium-rich manganese-based precursor material, the preparation method comprising the following steps:

[0069] (1) Add 33.5 kg of pure water, 100 g of sodium hydroxide solution, and 200 g of oxalic acid solution to the reactor as the reaction base liquid, and introduce nitrogen for 3 hours at a nitrogen flow rate of 50 L / h. The initial pH value of the base liquid is controlled to be 11.5;

[0070] (2) Under a nitrogen atmosphere, a nickel-cobalt-manganese mixed salt solution at a flow rate of 1.5 kg / h, a sodium hydroxide solution at a flow rate of 0.69 kg / h, and an oxalic acid solution at a flow rate of 0.18 kg / h are introduced into the bottom liquid of step (1) in parallel to carry out a coprecipitation reaction. After the coprecipitation reaction is continued for 10 hours, oxygen-containing gas is introduced, and then the coprecipitation reaction is continued. After the coprecipitation reaction is completed, the slurry after the reaction is completed is transferred to a suction filtration bottle, washed three times with alkaline solution and hot water respectively, and then dried at 120° C. to obtain the lithium-rich manganese-based precursor material;

[0071] The oxygen-containing gas is air, and the flow rate of the oxygen-containing gas is 5 L / h; the flow rate of the nitrogen is 50 L / h; the temperature of the coprecipitation reaction is 60°C, the pH is controlled between 10.6-11.0, and the stirring speed is 400 rpm;

[0072] The mass concentration of the nickel-cobalt-manganese mixed salt solution is 120 g / L, and the molar ratio of nickel ions, cobalt ions, and manganese ions is 0.30:0.05:0.65; the mass fraction of the sodium hydroxide solution is 35%, and the concentration of oxalic acid is 10 g / L.

[0073] Example 4

[0074] This embodiment provides a method for preparing a lithium-rich manganese-based precursor material, the preparation method comprising the following steps:

[0075] (1) Add 33.5 kg of pure water, 200 g of sodium hydroxide solution, and 250 g of oxalic acid solution to the reactor as the reaction base liquid, and introduce nitrogen for 3 hours at a nitrogen flow rate of 120 L / h. The initial pH value of the base liquid is controlled to be 12;

[0076] (2) Under a nitrogen atmosphere, a nickel-cobalt-manganese mixed salt solution at a flow rate of 1.5 kg / h, a sodium hydroxide solution at a flow rate of 0.69 kg / h, and an oxalic acid solution at a flow rate of 0.18 kg / h are introduced into the bottom liquid of step (1) in parallel to carry out a coprecipitation reaction. After the coprecipitation reaction is continued for 6 hours, oxygen-containing gas is introduced, and then the coprecipitation reaction is continued. After the coprecipitation reaction is completed, the slurry after the reaction is completed is transferred to a suction filtration bottle, washed three times with alkali solution and hot water respectively, and then dried at 120° C. to obtain the lithium-rich manganese-based precursor material;

[0077] The oxygen-containing gas is oxygen, and the flow rate of the oxygen-containing gas is 6 L / h; the flow rate of the nitrogen is 120 L / h; the temperature of the coprecipitation reaction is 58°C, the pH is controlled between 10.4-10.6, and the stirring speed is 600 rpm;

[0078] The mass concentration of the nickel-cobalt-manganese mixed salt solution is 100 g / L, and the molar ratio of nickel ions, cobalt ions, and manganese ions is 0.30:0.05:0.65; the mass fraction of the sodium hydroxide solution is 32%, and the concentration of oxalic acid is 8 g / L.

[0079] Example 5

[0080] This embodiment provides a method for preparing a lithium-rich manganese-based precursor material. The preparation method is the same as that of Example 1, except that the oxygen-containing gas is introduced after the coprecipitation reaction in step (2) has been carried out for 1 hour.

[0081] Example 6

[0082] This embodiment provides a method for preparing a lithium-rich manganese-based precursor material. The preparation method is the same as that of Example 1, except that the oxygen-containing gas is introduced after the coprecipitation reaction in step (2) has been carried out for 12 hours.

[0083] Example 7

[0084] This embodiment provides a method for preparing a lithium-rich manganese-based precursor material. The preparation method is the same as that of Example 1, except that the flow rate of the oxygen-containing gas in step (2) is 3 L / h.

[0085] Example 8

[0086] This embodiment provides a method for preparing a lithium-rich manganese-based precursor material. The preparation method is the same as that of Example 1, except that the flow rate of the oxygen-containing gas in step (2) is 20 L / h.

[0087] Example 9

[0088] This embodiment provides a method for preparing a lithium-rich manganese-based precursor material. The preparation method is the same as that of Example 1, except that the oxygen-containing gas in step (2) is oxygen.

[0089] Comparative Example 1

[0090] This comparative example provides a method for preparing a lithium-rich manganese-based precursor material. The preparation method is the same as Example 1 except that in step (2), no oxygen-containing gas is introduced, but the coprecipitation reaction is carried out in a nitrogen atmosphere.

[0091] The SEM image of the lithium-rich manganese-based precursor material obtained in this comparative example at a magnification of 3000 times is shown in FIG3 , and the SEM image at a magnification of 5000 times is shown in FIG4 .

[0092] Comparative Example 2

[0093] This comparative example provides a method for preparing a lithium-rich manganese-based precursor material. The preparation method is the same as Example 1, except that nitrogen is not introduced into step (1) and step (2), and the coprecipitation reaction is always carried out in the oxygen-containing gas atmosphere.

[0094] The lithium-rich manganese-based precursor materials obtained in the above examples and comparative examples were subjected to particle size distribution and BET tests, and the test results are shown in Table 1:

[0095] Table 1

[0096] From Table 1, we can see the following points:

[0097] (1) The (D90-D10) / D50 of the lithium-rich manganese precursor material obtained in this application is below 0.71, and the BET is between 25-30m 2 / g; Combining Examples 1-4 and Comparative Example 1, it can be seen that the particle size distribution of the highly dispersible and high specific surface area lithium-rich manganese-based precursor particles obtained in this application is relatively uniform, achieving the purpose of improving the dispersibility of the lithium-rich manganese-based precursor. The introduction of micro-oxidation effectively inhibits the collision and agglomeration of the precursor particles during the growth stage, and the BET of the precursor is significantly improved, maintaining at 25-30m 2 / g; the increase in BET is conducive to the full contact between the precursor and the lithium source in the subsequent positive electrode sintering process, which is crucial to the development of lithium-rich manganese-based positive electrode materials with stable structure and good cycle performance; it can be seen from Example 1 and Comparative Example 2 that if the coprecipitation reaction is always carried out in an oxygen-containing gas and nitrogen is not introduced, the lithium-rich manganese precursor is directly oxidized into nickel-cobalt-manganese oxide, and there are a large number of impurities such as Mn3O4 and MnO2, and the particles are agglomerated and adhered to each other, and the overall morphology and dispersibility are poor, which seriously affects the subsequent electrochemical performance of the positive electrode material; it can be seen from Example 1 and Examples 5-9 that the time of starting to introduce the oxygen-containing gas, the flow rate of the oxygen-containing gas, and the type of oxygen-containing gas will affect the degree of oxidation of the system, thereby affecting the dispersibility and specific surface area of ​​the product.

[0098] (2) It can be seen from the SEM images of Figures 1 to 4 that the secondary particles of the precursor in Comparative Example 1 adhere to each other and agglomerate during the growth stage, resulting in poor dispersion and overall morphology of the precursor particles; the introduction of micro-oxidation in the embodiment effectively inhibits the collision and agglomeration of the particles during the growth stage, and the obtained secondary particles of the precursor are uniformly distributed, the dispersion is significantly improved, and the sphericity of the overall morphology is also improved.

[0099] In summary, the present application provides a lithium-rich manganese-based precursor material, a preparation method and application thereof. The preparation method avoids the problems of dense particle growth, easy agglomeration and poor morphology in the existing preparation process of lithium-rich manganese precursor materials by introducing an oxidizing atmosphere during the growth stage of the precursor material, thereby obtaining a lithium-rich manganese-based precursor material with high dispersibility and high specific surface area.

[0100] The above description is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Those skilled in the art should understand that any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing a lithium-rich manganese-based precursor material, comprising the following steps: Under a protective gas atmosphere, a nickel-cobalt-manganese mixed salt solution, a precipitant solution and a complexing agent solution are mixed to carry out a coprecipitation reaction. When the coprecipitation reaction is carried out until the particles enter a growth stage, oxygen-containing gas is introduced, and then the coprecipitation reaction is continued to obtain the lithium-rich manganese-based precursor material.

2. The preparation method according to claim 1, wherein After the coprecipitation reaction has been going on for 2-10 hours, the oxygen-containing gas is introduced; Optionally, the oxygen-containing gas includes air or oxygen, and further optionally air; Optionally, the protective gas includes nitrogen and / or an inert gas.

3. The preparation method according to claim 1 or 2, wherein The oxygen-containing gas has an inlet flow rate of 5-15 L / h; Optionally, the inlet flow rate of the protective gas is 50-200 L / h.

4. The preparation method according to any one of claims 1 to 3, wherein: The precipitant solution includes sodium hydroxide solution and / or potassium hydroxide solution; Optionally, the mass fraction of the precipitant solution is 30-35wt%; Optionally, the complexing agent solution includes oxalic acid and / or ammonia water; Optionally, the mass concentration of the complexing agent solution is 2-10 g / L.

5. The preparation method according to any one of claims 1 to 4, wherein: The nickel-cobalt-manganese mixed salt solution, the precipitant solution and the complexing agent solution are simultaneously introduced into the base solution to perform a coprecipitation reaction; Optionally, the pH of the base solution is 11.5-12, and the base solution comprises water, a precipitant solution and a complexing agent solution; Optionally, in the nickel-cobalt-manganese mixed salt solution, the molar ratio of nickel ions, cobalt ions and manganese ions is x:y:z, wherein x+y+z=1, z≥0.6, 0<x<0.4, 0<y<0.

4.

6. The preparation method according to any one of claims 1 to 5, wherein: The coprecipitation reaction temperature is 50-60°C, the pH is 9.5-11.5, and the stirring speed is 400-700rpm; Optionally, after the coprecipitation reaction is completed, suction filtration, washing and drying are further performed; Optionally, the drying temperature is 100-150°C; Optionally, the washing comprises washing with alkaline solution and water respectively for 2-5 times.

7. The preparation method according to any one of claims 1 to 6, wherein: The preparation method comprises the following steps: Under a protective gas atmosphere, a nickel-cobalt-manganese mixed salt solution, a precipitant solution and a complexing agent solution are simultaneously introduced into the base liquid to carry out a coprecipitation reaction. After the coprecipitation reaction is carried out for 2-10 hours, an oxygen-containing gas is introduced, and then the coprecipitation reaction is continued. After the coprecipitation reaction is completed, suction filtration, washing and drying at a temperature of 100-150° C. are carried out to obtain the lithium-rich manganese-based precursor material; The oxygen-containing gas includes air or oxygen, and the flow rate of the oxygen-containing gas is 5-15 L / h; the protective gas includes nitrogen and / or inert gas, and the flow rate of the protective gas is 50-200 L / h; the temperature of the coprecipitation reaction is 50-60°C, the pH is 9.5-11.5, and the stirring speed is 400-700 rpm; The pH of the base solution is 11.5-12, and the base solution includes water, a precipitant solution and a complexing agent solution. In the nickel-cobalt-manganese mixed salt solution, the molar ratio of nickel ions, cobalt ions and manganese ions is x:y:z, wherein x+y+z=1, z≥0.6, 0<x<0.4, and 0<y<0.

4.

8. A lithium-rich manganese-based precursor material prepared by the preparation method according to any one of claims 1 to 7.

9. A lithium-rich manganese-based positive electrode material obtained by mixing and sintering the lithium-rich manganese-based precursor material as claimed in claim 8 with a lithium source.

10. A lithium ion battery comprising the lithium-rich manganese-based positive electrode material according to claim 9.

Images