Nickel-iron-manganese ternary precursor as well as preparation method and application thereof

Abstract

The invention provides a nickel-iron-manganese ternary precursor as well as a preparation method and application thereof. The preparation method comprises the following steps: providing a nickel-manganese binary solution; carrying out deoxygenation treatment on the nickel-manganese binary liquid, and then adding ferrous sulfate crystals under the condition of introducing high-purity inert gas to obtain a nickel-iron-manganese ternary liquid; and enabling the nickel-iron-manganese ternary solution, a precipitator and a complexing agent to flow into the base solution in parallel, and carrying out coprecipitation to obtain the nickel-iron-manganese ternary precursor. The method comprises the following steps: deoxygenating a nickel-manganese binary solution, and adding ferrous sulfate crystals under the protection of high-purity inert gas to construct a multi-defense system; according to the process, an oxidation source is removed from the source, secondary pollution is avoided, an exposure window of Fe < 2 + > is greatly shortened, oxidation of Fe < 2 + > and generation of colloid Fe (OH) 3 impurities are thoroughly inhibited, and the nickel-iron-manganese ternary precursor which is uniform in height, regular in shape and high in tap density can be obtained; and a foundation is laid for subsequent preparation of a positive electrode material with high energy density and long cycle stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of battery materials, and particularly relates to a nickel-iron-manganese ternary precursor and a preparation method and application thereof. BACKGROUND

[0002] In the preparation process of the positive electrode material of a secondary battery (such as a sodium ion battery or a lithium ion battery), a nickel-iron-manganese (Ni-Fe-Mn) ternary layered oxide material with high specific capacity and high stability is considered as one of the most promising technical routes. The performance of the material is largely dependent on the quality of the precursor, and the synthesis process of the nickel-iron-manganese ternary precursor is a major difficulty in the stability control of divalent iron (Fe 2+ ).

[0003] In the traditional coprecipitation preparation process, the iron source is usually introduced in the form of ferrous sulfate (FeSO4) solution and the like. However, Fe 2+ is extremely active in the alkaline aqueous solution environment, and is easily oxidized by trace dissolved oxygen in the solution and even in the environment, thereby being converted into trivalent iron (Fe 3+ ). The occurrence of this oxidation side reaction is almost instantaneous and difficult to completely suppress. Once Fe 3+ is generated, it will rapidly hydrolyze to generate colloidal iron hydroxide (Fe(OH)3) under the high pH condition of the reaction system. The Fe(OH)3colloid will seriously destroy the uniformity of the chemical composition of the precursor, causing the existence of component segregation and impurity phases in the positive electrode material after sintering. In addition, the Fe(OH)3colloid will interfere with the formation of normal crystal nuclei and the particle growth kinetics, inducing the formation of irregular, porous and even broken particle morphology, which will directly lead to a significant reduction in the tap density of the precursor powder, thereby directly reducing the volume energy density of the battery. In addition, irregular particle morphology and internal Fe(OH)3impurities will also affect the crystallization behavior of the positive electrode material in the sintering process, causing lattice defects, and damaging the structural stability and electrochemical performance of the positive electrode material.

[0004] Therefore, how to control the oxidation of Fe 2+ in the whole process and efficiently, and ensure that the precursor has high uniformity of components, regular morphology and high tap density, is a technical problem to be solved. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a nickel-iron-manganese ternary precursor and a preparation method and application thereof. The present application first performs oxygen removal treatment on the nickel-manganese binary liquid to reduce the dissolved oxygen content therein, thereby ensuring the stability of Fe 2+The stable presence of the substance creates a clean liquid environment. Subsequently, under the condition of maintaining positive pressure protection by continuously purging high-purity inert gas, solid ferrous sulfate crystals are directly added as the iron source. This avoids secondary oxygen pollution that may be introduced when preparing iron salt solutions, and, by utilizing the controllable dissolution process of solid crystals, greatly shortens the Fe... 2+ During the period when Fe is freely exposed to oxidation in solution, the process constructs a multi-layered defense system that significantly blocks Fe oxidation. 2+ To Fe 3+ The conversion pathway fundamentally eliminates the formation of colloidal Fe(OH)3 impurities, which is beneficial for preparing highly uniform, regularly morphologically regular, and high-tap-density nickel-iron-manganese ternary precursors. This lays a solid foundation for the structural stability and excellent electrochemical performance of subsequent cathode materials. Furthermore, this preparation process is highly controllable and easily achieves stable, large-scale production.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a nickel-iron-manganese ternary precursor, the method comprising the following steps:

[0008] We provide nickel-manganese binary solutions.

[0009] The nickel-manganese binary solution is subjected to oxygen removal treatment, and then ferrous sulfate crystals are added under the condition of passing high-purity inert gas to obtain a nickel-iron-manganese ternary solution.

[0010] The nickel-iron-manganese ternary solution, precipitant, and complexing agent are fed into the base solution in parallel to carry out a co-precipitation reaction to obtain the nickel-iron-manganese ternary precursor.

[0011] This invention first involves deoxygenating the nickel-manganese binary solution to reduce the dissolved oxygen content, thereby providing Fe... 2+ The stable presence of the substance creates a clean liquid environment. Subsequently, under the condition of maintaining positive pressure protection by continuously purging high-purity inert gas, solid ferrous sulfate crystals are directly added as the iron source. This avoids secondary oxygen pollution that may be introduced when preparing iron salt solutions, and, by utilizing the controllable dissolution process of solid crystals, greatly shortens the Fe... 2+ During the period when Fe is freely exposed to oxidation in solution, the process constructs a multi-layered defense system that significantly blocks Fe oxidation. 2+ To Fe 3+ The conversion pathway fundamentally eliminates the formation of colloidal Fe(OH)3 impurities, which is beneficial for preparing highly uniform, regularly morphologically regular, and high-tap-density nickel-iron-manganese ternary precursors. This lays a solid foundation for the structural stability and excellent electrochemical performance of subsequent cathode materials. Furthermore, this preparation process is highly controllable and easily achieves stable, large-scale production.

[0012] For example, in the nickel-manganese binary solution, the nickel salt may be nickel sulfate, nickel chloride, or nickel nitrate, etc., and the manganese salt may be manganese sulfate, manganese chloride, or manganese nitrate, etc.

[0013] Preferably, the concentration of the nickel-manganese binary solution is 95-105 g / L, for example, 95 g / L, 100 g / L, or 105 g / L, etc.

[0014] Preferably, the pH of the nickel-manganese binary solution is 1.5-2.5, for example, 1.5, 2, or 2.5, etc.

[0015] Preferably, in the nickel-iron-manganese ternary solution, the molar ratio of nickel ions, manganese ions, and ferrous ions is (33.1-33.5):(33.1-33.5):(33.1-33.5), wherein the selected range "33.1-33.5" of nickel ions may be 33.1, 33.2, 33.3, 33.4, or 33.5, etc., the selected range "33.1-33.5" of manganese ions may be 33.1, 33.2, 33.3, 33.4, or 33.5, etc., and the selected range "33.1-33.5" of ferrous ions may be 33.1, 33.2, 33.3, 33.4, or 33.5, etc.

[0016] Preferably, the specific steps of the oxygen removal treatment include:

[0017] Under stirring conditions, an inert gas with a purity of ≥99.9% (for example, 99.9%, 99.92%, 99.94%, 99.96%, 99.98%, 99.99%, or 99.999%, etc.) is bubbled into the nickel-manganese binary solution, so that the dissolved oxygen content in the nickel-manganese binary solution is ≤0.1 ppm (for example, 0.1 ppm, 0.08 ppm, 0.06 ppm, or 0.04 ppm, etc.).

[0018] The present application uses the above-mentioned process to remove oxygen, which can efficiently and completely remove the dissolved oxygen inside the solution, creating a safe oxygen-free environment for the introduction of subsequent iron sources.

[0019] In the present application, the purity of the inert gas is limited to ≥99.9%, which ensures that the protective gas itself does not contain oxygen and other oxidizing impurities, thereby avoiding the introduction of secondary pollution to the system during the bubbling process, and ensuring the absolute reliability of the oxygen removal treatment.

[0020] Preferably, the method of introducing high-purity inert gas is:

[0021] The inert gas with purity ≥ 99.9% (for example, it can be 99.9%, 99.92%, 99.94%, 99.96%, 99.98%, 99.99% or 99.999%, etc.) is maintained in positive pressure protection in the whole reactor, and the inert gas is continuously bubbled below the liquid surface.

[0022] The method of bubbling high-purity inert gas adopted by the present application helps to build a dynamic and static combined anaerobic protection system: maintaining inert gas in positive pressure in the whole reactor can effectively isolate the infiltration of external air; at the same time, continuously bubbling gas under the liquid surface can deeply and dynamically clean the liquid phase, which can not only remove trace oxygen diffused into the liquid phase in real time, but also promote the uniform mixing of reactants, optimize gas mass transfer, and provide a solid guarantee for the stable existence and uniform coprecipitation of Fe 2+ .

[0023] Preferably, the pH of the nickel-iron-manganese ternary solution is 1.4-1.8, for example, it can be 1.4, 1.5, 1.6, 1.7 or 1.8, etc.

[0024] Preferably, during the preparation of the nickel-iron-manganese ternary solution, the temperature of the solution is 20-26℃, for example, it can be 20℃, 21℃, 22℃, 23℃, 24℃, 25℃ or 26℃, etc.

[0025] Preferably, the preparation method comprises the following steps:

[0026] (1) In the preparation tank, a nickel-manganese binary solution with a concentration of 95-105 g / L is prepared; in the nickel-manganese binary solution, the molar ratio of nickel ions to manganese ions is (33.1-33.5):(33.1-33.5), and the pH is 1.5-2.5.

[0027] (2) An inert gas with purity ≥ 99.9% is bubbled into the preparation tank to replace the air in the tank, the temperature of the nickel-manganese binary solution is controlled to be 20-26℃, and the inert gas is bubbled into the nickel-manganese binary solution for oxygen removal treatment, so that the dissolved oxygen content in the nickel-manganese binary solution is ≤ 0.1 ppm, to obtain the oxygen-removed nickel-manganese binary solution.

[0028] Under the condition of maintaining inert gas with purity ≥ 99.9% in positive pressure protection in the whole preparation tank, and continuously bubbling inert gas under the liquid surface, ferrous sulfate crystal particles are added to the preparation tank, and mixed uniformly to obtain a nickel-iron-manganese ternary solution with a pH of 1.4-1.8; in the nickel-iron-manganese ternary solution, the molar ratio of nickel ions, manganese ions and ferrous ions is (33.1-33.5):(33.1-33.5):(33.1-33.5); wherein the inert gas includes nitrogen.

[0029] (3) The nickel-iron-manganese ternary liquid, the precipitant and the complexing agent are passed into the reactor in which the bottom liquid is located in a concurrent manner, the pH of the reaction system is controlled to be 9.7-11.5 (for example, it can be 9.7, 10, 10.5, 11 or 11.5, etc.), the temperature is controlled to be 50-60℃ (for example, it can be 50℃, 55℃ or 60℃, etc.), and the co-precipitation reaction is carried out for 60-90h (for example, it can be 60h, 70h, 80h or 90h, etc.), so as to obtain a reaction product slurry; wherein the bottom liquid comprises water, and the atmosphere in the reactor is an inert atmosphere (for example, it can be nitrogen, etc.).

[0030] (4) The reaction product slurry is aged, filtered, washed and dried, so as to obtain the nickel-iron-manganese ternary precursor.

[0031] In the second aspect, the present application provides a nickel-iron-manganese ternary precursor, which is prepared by the preparation method in the first aspect.

[0032] Preferably, the tap density of the nickel-iron-manganese ternary precursor is ≥1.4g / cm 3 , for example, it can be 1.4g / cm 3 , 1.45g / cm 3 , 1.50g / cm 3 , 1.55g / cm 3 or 1.6g / cm 3 , etc.

[0033] Preferably, the particle size D50 of the nickel-iron-manganese ternary precursor is 3.2-3.8μm, for example, it can be 3.2μm, 3.3μm, 3.4μm, 3.5μm, 3.6μm, 3.7μm or 3.8μm, etc.

[0034] In the third aspect, the present application provides a positive electrode material, wherein the raw material for preparing the positive electrode material comprises the nickel-iron-manganese ternary precursor in the second aspect.

[0035] For example, the positive electrode material can be a lithium ion positive electrode material or a sodium ion positive electrode material, etc.

[0036] In the fourth aspect, the present application provides a secondary battery, wherein the positive electrode material in the third aspect is included in the secondary battery.

[0037] For example, the secondary battery can be a lithium ion battery or a sodium ion battery, etc.

[0038] The numerical range in the present application not only includes the point values listed above, but also includes any point values between the above numerical ranges which are not listed, and the specific point values included in the range are not listed due to the limitation of the length and the consideration of simplicity.

[0039] Compared with the prior art, the present application has the following beneficial effects:

[0040] The present application first performs oxygen removal treatment on the nickel-manganese binary solution to reduce the dissolved oxygen content therein, thereby creating a clean liquid phase environment for the stable existence of Fe 2+ , and then directly adds solid ferrous sulfate crystals as the iron source under the condition that high-purity inert gas is continuously fed to maintain positive pressure protection, which on the one hand avoids the secondary oxygen pollution possibly introduced when preparing the iron salt solution, and on the other hand greatly shortens the period of Fe 2+ being exposed to oxidation in the solution. Therefore, the process constructs a multiple defense system, greatly blocks the conversion of Fe 2+ to Fe 3+ , fundamentally eliminates the generation of colloidal Fe(OH)3impurities, and is beneficial to the preparation of highly uniform, regular-shaped and high-tapped-density nickel-iron-manganese ternary precursors, which lays a solid foundation for the structural stability and excellent electrochemical performance of the subsequent positive electrode material. In addition, the preparation process has strong controllability and is easy to realize stable large-scale production. DETAILED DESCRIPTION

[0041] The technical solutions of the present application will be further described below through specific embodiments. 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 on the present application.

[0042] Embodiment 1

[0043] The present embodiment provides a preparation method of a nickel-iron-manganese ternary precursor, which comprises the following steps:

[0044] (1) A nickel-manganese sulfate solution with a concentration of 100 g / L is configured in a configuration tank; in the nickel-manganese sulfate solution, the molar ratio of nickel ions to manganese ions is 33.3:33.3, and the pH is 2.

[0045] (2) Pure nitrogen gas with a purity of 99.99% is fed to the configuration tank to replace the air in the tank, the temperature of the nickel-manganese binary solution is controlled to be 25°C, and nitrogen gas is fed to the nickel-manganese binary solution for bubble oxygen removal treatment, so that the dissolved oxygen content in the nickel-manganese binary solution is ≤0.1 ppm, to obtain a nickel-manganese sulfate solution after oxygen removal.

[0046] Under the condition that pure nitrogen gas with a purity of 99.99% is continuously fed to bubble below the liquid surface while maintaining positive pressure protection in the whole configuration tank, ferrous sulfate crystal particles are added to the configuration tank, and mixed uniformly to obtain a nickel-iron-manganese ternary solution with a pH of 1.6; in the nickel-iron-manganese ternary solution, the molar ratio of nickel ions, manganese ions and ferrous ions is 33.3:33.3:33.3.

[0047] (3) passing the nickel-iron-manganese ternary liquid, the precipitant and the complexing agent into a reaction kettle in which a bottom liquid is located in a concurrent flow, controlling the pH of the reaction system to be 10.6 and the temperature to be 55℃, and performing a coprecipitation reaction for 75h to obtain a reaction product slurry; wherein the bottom liquid is water, and the kettle atmosphere of the reaction kettle is nitrogen.

[0048] (4) performing aging, filtration, washing and drying on the reaction product slurry to obtain a nickel-manganese-iron ternary precursor.

[0049] Example 2

[0050] The embodiment provides a preparation method of a nickel-iron-manganese ternary precursor, and the preparation method comprises the following steps:

[0051] (1) configuring a nickel-manganese sulfate solution with a concentration of 95g / L in a configuration tank; in the nickel-manganese sulfate solution, the molar ratio of nickel ions to manganese ions is 33.1:33.5, and the pH is 1.5.

[0052] (2) passing nitrogen gas with a purity of 99.99% into the configuration tank to replace the air in the tank, controlling the temperature of the nickel-manganese binary liquid to be 20℃, and at the same time, passing nitrogen gas into the nickel-manganese binary liquid to perform bubble oxygen removal treatment, so that the dissolved oxygen content in the nickel-manganese binary liquid is ≤0.1ppm, to obtain an oxygen-removed nickel-manganese sulfate solution.

[0053] Under the condition of maintaining a nitrogen gas positive pressure protection with a purity of 99.99% in the whole configuration tank and continuously passing nitrogen gas to bubble under the liquid surface, ferrous sulfate crystal particles are added into the configuration tank, and are uniformly mixed to obtain a nickel-iron-manganese ternary liquid with a pH of 1.4; in the nickel-iron-manganese ternary liquid, the molar ratio of nickel ions, manganese ions and ferrous ions is 33.1:33.5:33.1.

[0054] (3) passing the nickel-iron-manganese ternary liquid, the precipitant and the complexing agent into a reaction kettle in which a bottom liquid is located in a concurrent flow, controlling the pH of the reaction system to be 9.7 and the temperature to be 50℃, and performing a coprecipitation reaction for 90h to obtain a reaction product slurry; wherein the bottom liquid is water, and the kettle atmosphere of the reaction kettle is nitrogen.

[0055] (4) performing aging, filtration, washing and drying on the reaction product slurry to obtain a nickel-manganese-iron ternary precursor.

[0056] Example 3

[0057] The embodiment provides a preparation method of a nickel-iron-manganese ternary precursor, and the preparation method comprises the following steps:

[0058] (1) In the configuration tank, a nickel-manganese sulfate solution with a concentration of 105 g / L is configured; in the nickel-manganese sulfate solution, the molar ratio of nickel ions to manganese ions is 33.5:33.1, and the pH is 2.5.

[0059] (2) Pure nitrogen gas with a purity of 99.99% is introduced into the configuration tank to replace the air in the tank, and the temperature of the nickel-manganese binary liquid is controlled at 26°C. At the same time, nitrogen gas is introduced into the nickel-manganese binary liquid for bubble oxygen removal treatment, so that the dissolved oxygen content in the nickel-manganese binary liquid is ≤0.1 ppm, and an oxygen-removed nickel-manganese sulfate solution is obtained.

[0060] Under the condition of maintaining a positive pressure protection of nitrogen gas with a purity of 99.99% in the whole configuration tank and continuously bubbling nitrogen gas below the liquid surface, ferrous sulfate crystal particles are added to the configuration tank, and mixed uniformly to obtain a nickel-iron-manganese ternary liquid with a pH of 1.8; in the nickel-iron-manganese ternary liquid, the molar ratio of nickel ions, manganese ions and ferrous ions is 33.5:33.1:33.5.

[0061] (3) The nickel-iron-manganese ternary liquid, a precipitating agent and a complexing agent are introduced into a reaction kettle in which a bottom liquid is located, and the pH of the reaction system is controlled at 11.5 and the temperature is controlled at 60°C, and a co-precipitation reaction is carried out for 60 h to obtain a reaction product slurry; wherein the bottom liquid is water, and the gas atmosphere in the reaction kettle is nitrogen.

[0062] (4) The reaction product slurry is aged, filtered, washed and dried to obtain a nickel-manganese-iron ternary precursor.

[0063] Example 4

[0064] The difference between this embodiment and Example 1 is that in step (2), nitrogen gas with a purity of 99% is introduced to replace the air in the kettle.

[0065] The rest of the preparation method and parameters remain the same as in Example 1.

[0066] Example 5

[0067] The difference between this embodiment and Example 1 is that in step (2), nitrogen gas is not continuously bubbled below the liquid surface.

[0068] The rest of the preparation method and parameters remain the same as in Example 1.

[0069] Example 6

[0070] The difference between this embodiment and Example 1 is that in step (2), the whole reaction kettle is maintained under a positive pressure protection of nitrogen gas with a purity of 99%.

[0071] The rest of the preparation method and parameters remain the same as in Example 1.

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is that the oxygen removal process described in step (2) is not performed, i.e., the nickel-manganese binary liquid and the ferrous sulfate crystals are mixed directly.

[0074] The rest of the preparation method and parameters remain the same as Example 1.

[0075] Comparative Example 2

[0076] The difference between this comparative example and Example 1 is that the ferrous sulfate crystals in step (2) are replaced by a ferrous sulfate solution.

[0077] The rest of the preparation method and parameters remain the same as Example 1.

[0078] Performance test

[0079] I. Tap density and particle size tests were performed on the nickel-iron-manganese ternary precursor provided in the above examples and comparative examples. The tap density test was performed according to GB / T 5162-2021 "Metallic powders - Determination of tap density". The particle size test was performed according to GB / T 19077-2016 "Particle size analysis - Laser diffraction method".

[0080] II. The nickel-iron-manganese ternary precursor provided in the above examples and comparative examples was mixed with sodium carbonate and sintered to obtain a positive electrode material. Then, the positive electrode material, acetylene black, and polyvinylidene fluoride were mixed in a mass ratio of 8:1:1 and added to N-methyl pyrrolidone to obtain a positive electrode slurry. The positive electrode slurry was then coated on an aluminum foil to obtain a positive electrode sheet. A metal sodium sheet was used as a negative electrode sheet. A polypropylene porous membrane was used as a separator. An electrolyte was 1 mol / L NaPF6 / EC+DEC+DMC (volume ratio of EC, DEC, and DMC = 1:1:1). A button cell was prepared in an argon-filled glove box.

[0081] The button cell was subjected to a cycle performance test. The test conditions included room temperature 25℃, charge-discharge cutoff voltage 2.0-4.0V, 0.2C charge-discharge rate, 200 cycles, and recording the capacity retention rate.

[0082] The results are shown in Table 1.

[0083] Table 1

[0084]

[0085] Analysis:

[0086] As shown in Table 1, the present application first performs oxygen removal treatment on the nickel-manganese binary liquid to reduce the dissolved oxygen content, thereby providing a suitable environment for the reduction of Fe 2+The stable existence of the clean liquid phase environment creates a clean liquid phase environment, and then under the condition of continuously passing high-purity inert gas to maintain positive pressure protection, solid ferrous sulfate crystals are directly added as the iron source. On the one hand, the secondary oxygen pollution possibly introduced during the preparation of the iron salt solution is avoided, and on the other hand, by means of the controllable dissolution process of the solid crystals, the Fe 2+ The period of free exposure to oxidation in the solution. Therefore, the process builds a multiple defense system, greatly blocking the Fe 2+ The conversion of Fe 3+ The conversion of Fe

[0087] It can be known from the comparison between Example 1 and Example 4 that if the purity of the nitrogen gas passed in step (2) is 99%, compared with 99.99%, the size of TD is improved by increasing the purity of the nitrogen gas, thereby improving the electrochemical performance of the sodium ion battery.

[0088] It can be known from the comparison between Example 1 and Example 5 that if nitrogen gas is not continuously passed below the liquid surface for bubbling in step (3), it is difficult to effectively improve TD, and the influence on the electrochemical performance of the sodium ion battery is great.

[0089] It can be known from the comparison between Example 1 and Example 6 that if the purity of the nitrogen gas maintained in the whole reaction kettle is 99% under positive pressure protection, instead of 99.99%, the oxidation of ferrous ions in the ternary liquid may occur during the reaction process, resulting in a smaller TD of the precursor, and further affecting the electrochemical performance of the battery.

[0090] It can be known from the comparison between Example 1 and Comparative Example 1 that if the oxygen removal process in step (2) is not performed, that is, the nickel-manganese binary liquid and ferrous sulfate crystals are directly mixed, the oxidation of the ferrous part will occur, which will result in a decrease in TD and affect the electrochemical performance of the sodium ion battery.

[0091] It can be known from the comparison between Example 1 and Comparative Example 2 that if the ferrous sulfate crystals are replaced by a ferrous sulfate solution, the number of steps is increased, the risk of oxidation of ferrous ions is increased, TD is smaller, and the electrochemical performance of the sodium ion battery is further affected.

[0092] It should be noted that the process method of the present application is illustrated by the above examples, but the present application is not limited to the above process steps, that is, it does not mean that the present application must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvement on the present application, equivalent replacement of the raw materials selected by the present application, addition of auxiliary ingredients, selection of specific methods, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing a nickel-iron-manganese ternary precursor, characterized in that, The preparation method comprises the following steps: The preparation method comprises the following steps: The preparation method comprises the following steps:

2. The production method according to claim 1, characterized by, The preparation method comprises the following steps: The concentration of the nickel-manganese binary solution is 95-105 g / L; And / or, the pH of the nickel-manganese binary solution is 1.5-2.5; 3. The production method according to claim 1 or 2, characterized by, And / or, in the nickel-iron-manganese ternary solution, the molar ratio of nickel ions, manganese ions and ferrous ions is (33.1-33.5):(33.1-33.5):(33.1-33.5). The specific steps of the oxygen removal treatment include:

4. The production method according to any one of claims 1 to 3, characterized by, Under stirring, the inert gas with a purity of ≥99.9% is bubbled into the nickel-manganese binary solution to make the dissolved oxygen content in the nickel-manganese binary solution ≤0.1 ppm. The method for introducing the high-purity inert gas is:

5. The method of any one of claims 1-4, wherein, The inert gas with a purity of ≥99.9% is continuously bubbled below the liquid surface under the positive pressure protection of the inert gas in the whole configuration tank. The pH of the nickel-iron-manganese ternary solution is 1.4-1.8; 6. The method of any one of claims 1-5, wherein, And / or, during the configuration process of the nickel-iron-manganese ternary solution, the solution temperature is 20-26 ℃. The preparation method comprises the following steps: (1) In the configuration tank, a nickel-manganese binary solution with a concentration of 95-105 g / L is configured; in the nickel-manganese binary solution, the molar ratio of nickel ions and manganese ions is (33.1-33.5):(33.1-33.5), and the pH is 1.5-2.5; (2) The inert gas with a purity of ≥99.9% is introduced into the configuration tank to replace the air in the tank, the temperature of the nickel-manganese binary solution is controlled to be 20-26 ℃, and the inert gas is bubbled into the nickel-manganese binary solution to perform oxygen removal treatment, so that the dissolved oxygen content in the nickel-manganese binary solution is ≤0.1 ppm, to obtain a nickel-manganese binary solution after oxygen removal; Under the positive pressure protection of the inert gas with a purity of ≥99.9% in the whole configuration tank, the inert gas is continuously bubbled below the liquid surface, and the ferrous sulfate crystal particles are added into the configuration tank, and mixed uniformly to obtain a nickel-iron-manganese ternary solution with a pH of 1.4-1.8; in the nickel-iron-manganese ternary solution, the molar ratio of nickel ions, manganese ions and ferrous ions is (33.1-33.5):(33.1-33.5):(33.1-33.5); wherein, the inert gas includes nitrogen; (3) The nickel-iron-manganese ternary solution, the precipitating agent and the complexing agent are passed into the reaction kettle where the bottom liquid is located in a concurrent manner, the pH of the reaction system is controlled to be 9.7-11.5, and the temperature is controlled to be 50-60 ℃, and the co-precipitation reaction is performed for 60-90 h to obtain a reaction product slurry; wherein, the bottom liquid includes water, and the gas atmosphere in the reaction kettle is inert atmosphere; 7. A nickel-iron-manganese ternary precursor, characterized in that, (4) The reaction product slurry is aged, filtered, washed and dried to obtain a nickel-iron-manganese ternary precursor. The nickel-iron-manganese ternary precursor is prepared by the preparation method in any one of claims 1-6.

8. The nickel-iron-manganese ternary precursor according to claim 7, characterized in that, The tap density of the nickel-iron-manganese ternary precursor is ≥1.4 g / cm 3 ; And / or, the particle size D50 of the nickel-iron-manganese ternary precursor is 3.2-3.8 μm.

9. A positive electrode material, characterized by, The preparation raw material of the positive electrode material comprises the nickel-iron-manganese ternary precursor according to claim 7 or 8.

10. A secondary battery characterized by comprising: The secondary battery comprises the positive electrode material according to claim 9.

Images