A lithium-rich manganese-based carbonate precursor, a preparation method and application thereof

Abstract

The application provides a lithium-rich manganese-based carbonate precursor, a preparation method and application thereof, and belongs to the technical field of battery material precursor preparation. In the preparation process, a morphology adjusting agent solution is added, and the type of the morphology adjusting agent is controlled, inorganic / organic composite crystal face regulation is formed, ammonium lactate (organic slow release) and sodium tetraborate (inorganic crystal face modification) are complementary in function, double crystal face selective passivation is realized, spherical morphology is precisely regulated, a lactate organic ligand is used for long-range steric hindrance, a macroscopic modification particle overall contour is used for eliminating sharp edges and corners, a borate inorganic anion is used for short-range strong electrostatic adsorption, the growth rate of a specific crystal face is precisely regulated, the thickness and porosity of a secondary spherical flake layer are controlled, and the combination of the two can regulate the "primary particle size" and "secondary spherical sphericity", so that the prepared precursor has high sphericity, a smooth and dense surface, no peeling and no powder dropping, and is suitable for lithium ion battery positive electrode materials.

Description

Technical Field

[0001] This invention belongs to the field of battery material precursor preparation technology, specifically relating to a lithium-rich manganese-based carbonate precursor, its preparation method, and its application. Background Technology

[0002] Lithium-rich manganese-based cathode materials are a research hotspot in high-energy-density lithium batteries due to their high specific capacity and high operating voltage. They are mainly prepared by mixing lithium-rich manganese-based carbonate precursors with lithium sources and then calcining at high temperatures. The lithium-rich manganese-based carbonate precursors are primarily prepared using a sodium carbonate-ammonia-metal salt co-precipitation system. However, the precursor particles prepared using this system suffer from surface peeling, which affects the performance of the subsequently prepared lithium-rich manganese-based cathode materials and lithium batteries. Therefore, improving the preparation method to address the surface peeling problem of the lithium-rich manganese-based carbonate precursor morphology has become a pressing technical issue in this field. Summary of the Invention

[0003] The purpose of this invention is to provide a lithium-rich manganese-based carbonate precursor, its preparation method, and its applications. The lithium-rich manganese-based carbonate precursor prepared by the method provided by this invention has high sphericity, a smooth and dense surface, and is free from peeling and powdering.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing a lithium-rich manganese-based carbonate precursor, comprising the following steps: (1) Mix the precipitant solution, complexing agent solution, buffer salt solution, morphology modifier solution and water to obtain the initial reaction base solution; (2) The metal salt solution, precipitant solution, complexing agent solution, buffer salt solution and morphology modifier solution are added in parallel to the starting reaction substrate obtained in step (1) to carry out a co-precipitation reaction to obtain an intermediate; (3) The intermediate obtained in step (2) is aged to obtain a lithium-rich manganese-based carbonate precursor; The morphology modifiers in the morphology modifier solutions of steps (1) and (2) include sodium tetraborate and ammonium lactate; the molar ratio of sodium tetraborate and ammonium lactate is (2~5):1.

[0005] Preferably, the precipitant in the precipitant solution in steps (1) and (2) includes sodium carbonate and / or potassium carbonate; the concentration of the precipitant solution is 0.5~3 mol / L.

[0006] Preferably, the complexing agent solution in steps (1) and (2) is ammonia water; the concentration of the complexing agent solution is 0.2~2 mol / L.

[0007] Preferably, the buffer salt in the buffer salt solution in steps (1) and (2) includes ammonium chloride and / or boric acid; the concentration of the buffer salt solution is 0.5~1.5 mol / L.

[0008] Preferably, in step (1), the volume ratio of water, precipitant solution, complexing agent solution, buffer salt solution and morphology modifier solution is (40~100):(2~10):(1~5):(0.5~2):(0.1~1).

[0009] Preferably, the metal in the metal salt solution in step (2) includes one or more of nickel, cobalt and manganese; the concentration of the metal salt solution is 0.5~2.5 mol / L.

[0010] Preferably, in step (2), the flow rate of the metal salt solution is 3~8 L / h, the flow rate of the precipitant solution is 4~8 L / h, the flow rate of the complexing agent solution is 3~6 L / h, the flow rate of the buffer salt solution is 1~2 L / h, and the flow rate of the morphology modifier solution is 0.1~1 L / h.

[0011] Preferably, the temperature of the co-precipitation reaction in step (2) is 45~75℃; the particle size D50 of the intermediate is 10±0.5μm.

[0012] The present invention also provides a lithium-rich manganese-based carbonate precursor prepared by the preparation method described in the above technical solution.

[0013] The present invention also provides the application of the lithium-rich manganese-based carbonate precursor described in the above technical solution in lithium batteries.

[0014] This invention provides a method for preparing a lithium-rich manganese-based carbonate precursor, comprising the following steps: (1) mixing a precipitant solution, a complexing agent solution, a buffer salt solution, a morphology modifier solution and water to obtain a starting reaction base solution; (2) adding a metal salt solution, a precipitant solution, a complexing agent solution, a buffer salt solution and a morphology modifier solution in parallel to the starting reaction base solution obtained in step (1) for co-precipitation reaction to obtain an intermediate; (3) aging the intermediate obtained in step (2) to obtain a lithium-rich manganese-based carbonate precursor; the morphology modifier in the morphology modifier solution in steps (1) and (2) includes sodium tetraborate and ammonium lactate; the molar ratio of sodium tetraborate and ammonium lactate is (2~5):1. This invention adds a morphology modifier solution and controls the type of morphology modifier during the preparation process to form an inorganic / organic composite crystal facet control. Ammonium lactate (organic slow release) and sodium tetraborate (inorganic crystal facet modification) complement each other, selectively passivating the dual crystal faces and precisely controlling the spherical morphology. Lactate organic ligands provide long-range steric hindrance and macroscopically modify the overall particle outline, eliminating sharp edges. Borate inorganic anions provide short-range strong electrostatic adsorption and precisely control the growth rate of specific crystal faces, controlling the thickness and porosity of the secondary spherical layers. The combined use of these two can control the "primary particle size" and "secondary sphericity," resulting in a precursor with high sphericity, a smooth and dense surface, and no peeling or powdering, making it suitable for lithium-ion battery cathode materials. Attached Figure Description

[0015] Figure 1 SEM image of the lithium-rich manganese-based carbonate precursor prepared in Example 1; Figure 2 SEM image of the lithium-rich manganese-based carbonate precursor prepared in Example 2; Figure 3 SEM image of the lithium-rich manganese-based carbonate precursor prepared in Example 3; Figure 4 SEM image of the lithium-rich manganese-based carbonate precursor prepared in Comparative Example 1; Figure 5 SEM image of the lithium-rich manganese-based carbonate precursor prepared in Comparative Example 2; Figure 6 SEM image of the lithium-rich manganese-based carbonate precursor prepared in Comparative Example 3; Figure 7 SEM image of the lithium-rich manganese-based carbonate precursor prepared in Comparative Example 4. Detailed Implementation

[0016] This invention provides a method for preparing a lithium-rich manganese-based carbonate precursor, comprising the following steps: (1) Mix the precipitant solution, complexing agent solution, buffer salt solution, morphology modifier solution and water to obtain the initial reaction base solution; (2) The metal salt solution, precipitant solution, complexing agent solution, buffer salt solution and morphology modifier solution are added in parallel to the starting reaction substrate obtained in step (1) to carry out a co-precipitation reaction to obtain an intermediate; (3) The intermediate obtained in step (2) is aged to obtain a lithium-rich manganese-based carbonate precursor.

[0017] Unless otherwise specified, the present invention does not impose any special restrictions on the source of the raw materials, and products prepared by commercially available products or conventional preparation methods known to those skilled in the art are acceptable.

[0018] The present invention mixes a precipitant solution, a complexing agent solution, a buffer salt solution, a morphology modifier solution and water to obtain an initial reaction substrate.

[0019] In this invention, the precipitant in the precipitant solution preferably includes sodium carbonate and / or potassium carbonate; the solvent in the precipitant solution is preferably deionized water; and the concentration of the precipitant solution is preferably 0.5~3 mol / L. As one embodiment, the concentration of the precipitant solution can specifically be 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, or 3 mol / L.

[0020] In this invention, the complexing agent solution is preferably ammonia water; the solvent in the complexing agent solution is preferably deionized water; and the concentration of the complexing agent solution is preferably 0.2~2 mol / L. As one embodiment, the concentration of the complexing agent solution can specifically be 0.2 mol / L, 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, or 2 mol / L.

[0021] In this invention, the buffer salt in the buffer salt solution preferably includes ammonium chloride and / or boric acid; the solvent in the buffer salt solution is preferably deionized water; and the concentration of the buffer salt solution is preferably 0.5~1.5 mol / L. As one embodiment, the concentration of the buffer salt solution can specifically be 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, or 1.5 mol / L. The addition of a buffer salt solution in this invention can enhance the system's buffering capacity, suppress excessively high local pH values, and significantly reduce the risk of basic carbonate formation.

[0022] In this invention, the morphology modifier in the morphology modifier solution comprises sodium tetraborate and ammonium lactate; the molar ratio of sodium tetraborate to ammonium lactate is (2~5):1; the solvent in the morphology modifier solution is preferably deionized water; the concentration of the morphology modifier solution is preferably 0.1~1 mol / L. As one embodiment, the concentration of the morphology modifier solution may specifically be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, or 1 mol / L. This invention adds morphology modifiers and controls their specific types. Sodium tetraborate is responsible for selective adsorption on crystal faces, inhibition of particle aggregation, system buffering, and micro-framework confinement. It can occupy active sites on crystal faces, prevent the deposition of metal hydroxide ions on these crystal faces, and reduce the crystal face growth rate. Borate ions are negatively charged and preferentially adsorb high-energy crystal faces of precursor metal hydroxyl oxides, such as the (010) and (101) faces of transition metal hydroxides, forming a thin layer of metal borate with the system's metal ions and uniformly depositing on the surface of newly formed precursor particles. Ammonium lactate is responsible for ion slow release, coordination capping, and pH buffering. Lactate is a moderately strong bidentate chelating ligand: carboxyl O and metal ion Ni 2+ / Co 2+ / Mn 2+ After forming a stable five-membered chelate ring, the hydroxyl group assists in hydrogen bonding to stabilize the complex, constructing a soluble metal-lactic acid complex, significantly reducing the concentration of free metal ions in the solution; the precipitation changes from "instantaneous nucleation" to slow dissociation and sustained-release precipitation, with a uniform nucleation rate, small primary particles, and extremely narrow particle size distribution; excessive growth of angularity is inhibited, resulting in rounded particles; an organic adsorption layer is formed on the surface of the precursor particles, providing electrostatic and steric hindrance to prevent primary particle ripening and hard agglomeration, resulting in well-developed pores and controllable tap density in the precursor; ammonium lactate (organic sustained-release) + tetraboric acid Sodium (inorganic crystal facet modification) provides complementary functions, selectively passivating the dual crystal faces and precisely controlling the spherical morphology. Lactate organic ligands provide long-range steric hindrance, macroscopically modifying the overall particle outline and eliminating sharp edges. Borate inorganic anions provide short-range strong electrostatic adsorption, precisely controlling the growth rate of specific crystal faces and controlling the thickness and porosity of the secondary spherical layers. The combined use of these two can individually control the "primary grain size" and "secondary sphericity," which cannot be achieved simultaneously by a single regulator. As a result, the prepared precursor has high sphericity, a smooth and dense surface, and no peeling or powdering.

[0023] In this invention, the water is preferably deionized water.

[0024] In this invention, the preferred volume ratio of the water, precipitant solution, complexing agent solution, buffer salt solution, and morphology modifier solution is (40~100):(2~10):(1~5):(0.5~2):(0.1~1). As one embodiment, the volume ratio of the water, precipitant solution, complexing agent solution, buffer salt solution, and morphology modifier solution can be specifically 40:2:1:0.5:0.2, 60:5:3:1:0.5, or 80:8:5:1.5:0.8.

[0025] The present invention does not have any special limitations on the operation of mixing the precipitant solution, complexing agent solution, buffer salt solution, morphology modifier solution and water. The raw materials can be mixed evenly by means of technical solutions known to those skilled in the art.

[0026] After obtaining the initial reaction substrate, the present invention adds a metal salt solution, a precipitant solution, a complexing agent solution, a buffer salt solution, and a morphology modifier solution in parallel to the initial reaction substrate to carry out a co-precipitation reaction to obtain an intermediate.

[0027] In this invention, the metal in the metal salt solution preferably includes one or more of nickel, cobalt, and manganese, more preferably nickel-manganese or nickel-cobalt-manganese; the metal salt preferably includes a metal sulfate, a metal acetate, or a metal nitrate; the solvent in the metal salt solution is preferably deionized water. In this invention, when the metal is nickel-manganese or nickel-cobalt-manganese, the molar ratio of nickel, cobalt, and manganese is preferably (10~50):(0~20):(50~80). As one embodiment, the molar ratio of nickel, cobalt, and manganese can be specifically 18:16:66, 24:12:64, or 45:0:55.

[0028] In this invention, the concentration of the metal salt solution is preferably 0.5~2.5 mol / L. As one embodiment, the concentration of the metal salt solution can specifically be 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, or 2.5 mol / L. In this invention, the concentration of the metal salt solution refers to the total concentration of all metal ions.

[0029] In this invention, the types and concentrations of the precipitant solution, complexing agent solution, buffer salt solution, and morphology modifier solution are preferably the same as those of the precipitant solution, complexing agent solution, buffer salt solution, and morphology modifier solution described above, and will not be repeated here.

[0030] In this invention, the flow rate of the metal salt solution is preferably 3-8 L / h; the flow rate of the precipitant solution is preferably 4-8 L / h; the flow rate of the complexing agent solution is preferably 3-6 L / h; the flow rate of the buffer salt solution is preferably 1-2 L / h; and the flow rate of the morphology modifier solution is preferably 0.1-1 L / h. In one embodiment, the flow rate of the metal salt solution can specifically be 3 L / h, 3.5 L / h, 4 L / h, 4.5 L / h, 5 L / h, 5.5 L / h, 6 L / h, 6.5 L / h, 7 L / h, 7.5 L / h, or 8 L / h; the flow rate of the precipitant solution can specifically be 4 L / h, 4.5 L / h, 5 L / h, 5.5 L / h, 6 L / h, 6.5 L / h, 7 L / h, 7.5 L / h, or 8 L / h; and the flow rate of the complexing agent solution can specifically be 3 L / h, 3.5 L / h, 4 L / h, or 4.5 L / h. The flow rate of the buffer salt solution can be specifically 1L / h, 1.1L / h, 1.2L / h, 1.3L / h, 1.4L / h, 1.5L / h, 1.6L / h, 1.7L / h, 1.8L / h, 1.9L / h, or 2L / h; the flow rate of the morphology modifier solution can be specifically 0.1L / h, 0.2L / h, 0.3L / h, 0.4L / h, 0.5L / h, 0.6L / h, 0.7L / h, 0.8L / h, 0.9L / h, or 1L / h.

[0031] In this invention, each solution is preferably introduced into the initial reaction substrate using a metering pump.

[0032] In this invention, the temperature of the coprecipitation reaction is preferably 45-75°C; the pH value of the coprecipitation reaction is preferably 7-10; the coprecipitation reaction is preferably carried out under stirring and an inert atmosphere; the stirring rate is preferably 500-2000 rpm; the inert atmosphere is preferably nitrogen; and the nitrogen flow rate is preferably 1-20 L / min. As one embodiment, the temperature of the coprecipitation reaction can specifically be 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, or 75°C; the pH value of the coprecipitation reaction can specifically be 7, 8, 9, or 10; the stirring rate can specifically be 500 rpm, 800 rpm, 1000 rpm, 1200 rpm, 1500 rpm, 1800 rpm, or 2000 rpm; and the nitrogen flow rate can specifically be 1 L / min, 5 L / min, 8 L / min, 10 L / min, 12 L / min, 15 L / min, 18 L / min, or 20 L / min.

[0033] In this invention, the particle size D50 of the intermediate is preferably 10 ± 0.5 μm. This invention does not have a specific limitation on the time of the co-precipitation reaction, as long as the particle size of the intermediate reaches the desired range. This invention preferably uses an Omec SCF-105B to test the particle size of the intermediate.

[0034] In this invention, an inert gas is introduced into the initial reaction solution, stirring and heating are started, and after the temperature reaches the coprecipitation reaction temperature, the metal salt solution, precipitant solution, complexing agent solution, buffer salt solution and morphology regulator solution are added in parallel through a metering pump under constant temperature conditions until the coprecipitation reaction is completed and the feeding is stopped.

[0035] After obtaining the intermediate, the present invention ages the intermediate to obtain a lithium-rich manganese-based carbonate precursor.

[0036] In this invention, the aging temperature is preferably 75~95℃; the aging time is preferably 1~5h. As one embodiment, the aging temperature can be specifically 75℃, 78℃, 80℃, 82℃, 85℃, 88℃, 90℃, 92℃ or 95℃; the aging time can be specifically 1h, 2h, 3h, 4h or 5h.

[0037] After aging, the present invention preferably washes, dries and sieves the aged product in sequence to obtain a lithium-rich manganese-based carbonate precursor.

[0038] In this invention, the water temperature during washing is preferably 30-80℃, more preferably 50℃; the drying temperature is preferably 80-120℃, more preferably 100℃; and the sieve mesh size during sieving is preferably 200-400 mesh, more preferably 325 mesh. This invention does not impose any special limitations on the number of washing cycles or the drying time; any technical solution well-known to those skilled in the art can be used.

[0039] In this invention, the particle size D50 of the lithium-rich manganese-based carbonate precursor is preferably 10±0.5μm, 0.6<(D90-D10) / D50<0.8, and there are no impurities or abnormal secondary particles.

[0040] This invention addresses the problem of surface peeling in existing sodium carbonate-ammonia-metal salt coprecipitation systems. During the reaction, high supersaturation at a certain stage leads to rapid epitaxial growth of crystals, resulting in a loose surface layer. A sudden drop in supersaturation and a sudden increase in ammonia complexation slows or even halts growth, leading to poor bonding between new and old growth layers, with new layers covering older layers and interfacial defects causing surface peeling. This invention achieves a denser precursor morphology, a smooth, peel-free surface, uniform particle size distribution, and improved filtration performance through buffer solution construction, inorganic / organic composite crystal surface regulation, and precise control of buffer pH and complexation. The invention first prepares the initial reaction solution, then simultaneously introduces a metal salt solution, precipitant solution, complexing agent solution, buffer salt solution, and morphology regulator solution under constant temperature and stirring. The concentration and feed rate of each raw material, as well as the reaction pH and temperature, are controlled to complete nucleation and growth. After aging, washing, and drying, a dense, peel-free spherical carbonate precursor is obtained. The process of this invention is stable, low-cost, and easy to industrialize. The resulting precursor has high sphericity, a smooth and dense surface, no peeling or powdering, and good filtration, making it suitable for high-precision applications such as lithium-ion battery cathode materials.

[0041] The present invention also provides a lithium-rich manganese-based carbonate precursor prepared by the preparation method described in the above technical solution.

[0042] The lithium-rich manganese-based carbonate precursor prepared by this invention has high sphericity, a smooth and dense surface, and does not peel.

[0043] The present invention also provides the application of the lithium-rich manganese-based carbonate precursor described in the above technical solution in lithium batteries.

[0044] This invention involves using a lithium-rich manganese-based carbonate precursor, after lithium doping and high-temperature sintering, in lithium batteries. The high-temperature sintering process is not specifically limited in this invention; any technique well-known to those skilled in the art can be employed.

[0045] The present invention does not impose any special limitations on the operation of the application, and any technical solution known to those skilled in the art can be used.

[0046] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0047] Example 1 A method for preparing a lithium-rich manganese-based carbonate precursor is as follows: Metal salt aqueous solution: prepared from nickel sulfate, cobalt sulfate and manganese sulfate, with a molar ratio of nickel, cobalt and manganese of 18:16:66, and a total concentration of nickel, cobalt and manganese in the metal salt solution of 1.8 mol / L; Precipitating agent solution: sodium carbonate aqueous solution, 1.5 mol / L; Complexing agent solution: ammonia water, 0.8 mol / L; Buffer salt solution: ammonium chloride aqueous solution, 0.5 mol / L; The morphology modifier aqueous solution was prepared by mixing sodium tetraborate and ammonium lactate in a molar ratio of 2:1, with a total concentration of 0.3 mol / L. (1) Add 40L of deionized water, 2L of precipitant solution, 1L of complexing agent solution, 0.5L of buffer salt solution and 0.2L of morphology modifier solution to the reaction vessel to obtain the initial reaction base liquid; (2) Nitrogen gas (8L / min) is introduced into the initial reaction base liquid, stirring (800rpm) is started and heated. After the temperature reaches 50℃, under constant temperature of 50℃, a metering pump is introduced to feed the metal salt solution, precipitant solution, complexing agent solution, buffer salt solution and morphology regulator solution into the initial reaction base liquid in parallel. The flow rate of the metal salt solution is 3L / h, the flow rate of the precipitant solution is 4L / h, the flow rate of the complexing agent solution is 3L / h, the flow rate of the buffer salt solution is 1L / h, and the flow rate of the morphology regulator solution is 0.3L / h. The pH value of the reaction system is stabilized at 7.5. Co-precipitation reaction is carried out until the particle size D50 of the product reaches 10±0.5μm and the feed is stopped to obtain the intermediate. (3) The intermediate obtained was aged at 80°C for 2 hours, then washed with deionized water at 50°C, dried in a vacuum oven at 100°C, and sieved through a 325-mesh standard sieve to obtain a lithium-rich manganese-based carbonate precursor.

[0048] SEM image of the lithium-rich manganese-based carbonate precursor prepared in Example 1 is shown below. Figure 1 As shown. From Figure 1 As can be seen, the surface of the lithium-rich manganese-based carbonate precursor is not peeled and is uniform and dense.

[0049] Example 2 A method for preparing a lithium-rich manganese-based carbonate precursor is as follows: Metal salt aqueous solution: prepared from nickel acetate, cobalt acetate and manganese acetate, with a molar ratio of nickel, cobalt and manganese of 24:12:64, and a total concentration of nickel, cobalt and manganese in the metal salt solution of 2.1 mol / L; Precipitating agent solution: sodium carbonate aqueous solution, 2.5 mol / L; Complexing agent solution: ammonia water, 1.5 mol / L; Buffer salt solution: ammonium chloride aqueous solution, 1.2 mol / L; The morphology modifier aqueous solution was prepared by mixing sodium tetraborate and ammonium lactate in a molar ratio of 2:1, with a total concentration of 0.6 mol / L. (1) Add 60L of deionized water, 5L of precipitant solution, 3L of complexing agent solution, 1L of buffer salt solution and 0.5L of morphology modifier solution to the reaction vessel to obtain the initial reaction base liquid; (2) Nitrogen gas (14 L / min) is introduced into the initial reaction base liquid, stirring (1300 rpm) is started and heated. After the temperature reaches 60℃, under constant temperature of 60℃, a metering pump is introduced to feed the metal salt solution, precipitant solution, complexing agent solution, buffer salt solution and morphology regulator solution into the initial reaction base liquid in parallel. The flow rate of the metal salt solution is 6 L / h, the flow rate of the precipitant solution is 6 L / h, the flow rate of the complexing agent solution is 4 L / h, the flow rate of the buffer salt solution is 1.5 L / h, and the flow rate of the morphology regulator solution is 0.6 L / h. The pH value of the reaction system is stabilized at 8.0, and the co-precipitation reaction is carried out until the product particle size D50 reaches 10±0.5 μm and the feed is stopped to obtain the intermediate. (3) The intermediate obtained was aged at 80°C for 2 hours, then washed with deionized water at 50°C, dried in a vacuum oven at 100°C, and sieved through a 325-mesh standard sieve to obtain a lithium-rich manganese-based carbonate precursor.

[0050] SEM image of the lithium-rich manganese-based carbonate precursor prepared in Example 2 is shown below. Figure 2 As shown. From Figure 2 As can be seen, the surface of the lithium-rich manganese-based carbonate precursor is not peeled and is uniform and dense.

[0051] Example 3 A method for preparing a lithium-rich manganese-based carbonate precursor is as follows: Metal salt aqueous solution: prepared from nickel nitrate and manganese nitrate, with a molar ratio of nickel to manganese of 45:55, and a total concentration of nickel and manganese in the metal salt solution of 2.5 mol / L; Precipitating agent solution: sodium carbonate aqueous solution, 2.8 mol / L; Complexing agent solution: ammonia water, 1.8 mol / L; Buffer salt solution: ammonium chloride aqueous solution, 1.5 mol / L; The morphology modifier aqueous solution was prepared by mixing sodium tetraborate and ammonium lactate in a molar ratio of 2:1, with a total concentration of 0.8 mol / L. (1) Add 80L of deionized water, 8L of precipitant solution, 5L of complexing agent solution, 1.5L of buffer salt solution and 0.8L of morphology modifier solution to the reaction vessel to obtain the initial reaction base liquid; (2) Nitrogen gas (18 L / min) is introduced into the initial reaction base liquid, stirring (1800 rpm) is started and heated. After the temperature reaches 70℃, under constant temperature of 70℃, a metering pump is introduced to feed the metal salt solution, precipitant solution, complexing agent solution, buffer salt solution and morphology regulator solution into the initial reaction base liquid in parallel. The flow rate of the metal salt solution is 8 L / h, the flow rate of the precipitant solution is 8 L / h, the flow rate of the complexing agent solution is 5 L / h, the flow rate of the buffer salt solution is 1.8 L / h, and the flow rate of the morphology regulator solution is 0.8 L / h. The pH value of the reaction system is stabilized at 8.5, and the co-precipitation reaction is carried out until the product particle size D50 reaches 10±0.5 μm and the feed is stopped to obtain the intermediate. (3) The intermediate obtained was aged at 80°C for 2 hours, then washed with deionized water at 50°C, dried in a vacuum oven at 100°C, and sieved through a 325-mesh standard sieve to obtain a lithium-rich manganese-based carbonate precursor.

[0052] SEM image of the lithium-rich manganese-based carbonate precursor prepared in Example 3 is shown below. Figure 3 As shown. From Figure 3 As can be seen, the surface of the lithium-rich manganese-based carbonate precursor is not peeled and is uniform and dense.

[0053] Comparative Example 1 The only difference from Example 1 is that the morphology modifier solution is an aqueous solution of sodium tetraborate with a concentration of 0.3 mol / L; all other aspects are the same as in Example 1.

[0054] SEM image of the lithium-rich manganese-based carbonate precursor prepared in Comparative Example 1 is shown below. Figure 4 As shown. From Figure 4 As can be seen, the surface of the lithium-rich manganese-based carbonate precursor peels.

[0055] Comparative Example 2 The only difference from Example 2 is that the morphology modifier solution is an aqueous solution of ammonium lactate with a concentration of 0.6 mol / L; all other aspects are the same as in Example 2.

[0056] SEM image of the lithium-rich manganese-based carbonate precursor prepared in Comparative Example 2 is shown below. Figure 5 As shown. From Figure 5 As can be seen, the surface of the lithium-rich manganese-based carbonate precursor peels.

[0057] Comparative Example 3 The only difference from Example 3 is that the morphology-modifying agent solution is omitted; otherwise, they are the same as in Example 3.

[0058] SEM image of the lithium-rich manganese-based carbonate precursor prepared in Comparative Example 3 is shown below. Figure 6 As shown. From Figure 6As can be seen, the surface of the lithium-rich manganese-based carbonate precursor peels.

[0059] Comparative Example 4 The only difference from Example 1 is that the buffer salt solution and morphology modifier solution are omitted; otherwise, they are the same as in Example 1.

[0060] SEM image of the lithium-rich manganese-based carbonate precursor prepared in Comparative Example 4 is shown below. Figure 7 As shown. From Figure 7 As can be seen, the surface of the lithium-rich manganese-based carbonate precursor peels.

[0061] The results from the above examples and comparative examples show that adding ammonium chloride buffer solution to the coprecipitation reaction only enhances the system's buffering capacity, inhibits excessively high local pH, and significantly reduces the risk of basic carbonate formation. It does not directly improve the surface peeling effect. In addition, the mixed morphology modifier of sodium tetraborate and ammonium lactate can directly improve the surface peeling effect. Moreover, the two are used in combination and work synergistically, which cannot be achieved by using either one alone.

[0062] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a lithium-rich manganese-based carbonate precursor, characterized in that, Includes the following steps: (1) Mix the precipitant solution, complexing agent solution, buffer salt solution, morphology modifier solution and water to obtain the initial reaction base solution; (2) The metal salt solution, precipitant solution, complexing agent solution, buffer salt solution and morphology modifier solution are added in parallel to the starting reaction substrate obtained in step (1) to carry out a co-precipitation reaction to obtain an intermediate; (3) The intermediate obtained in step (2) is aged to obtain a lithium-rich manganese-based carbonate precursor; The morphology modifiers in the morphology modifier solutions of steps (1) and (2) include sodium tetraborate and ammonium lactate; the molar ratio of sodium tetraborate and ammonium lactate is (2~5):

1.

2. The preparation method according to claim 1, characterized in that, The precipitant in the precipitant solution in steps (1) and (2) includes sodium carbonate and / or potassium carbonate; the concentration of the precipitant solution is 0.5~3 mol / L.

3. The preparation method according to claim 1, characterized in that, The complexing agent solution in steps (1) and (2) is ammonia water; the concentration of the complexing agent solution is 0.2~2 mol / L.

4. The preparation method according to claim 1, characterized in that, The buffer salt in the buffer salt solution in steps (1) and (2) includes ammonium chloride and / or boric acid; the concentration of the buffer salt solution is 0.5~1.5 mol / L.

5. The preparation method according to claim 1, characterized in that, In step (1), the volume ratio of water, precipitant solution, complexing agent solution, buffer salt solution and morphology modifier solution is (40~100):(2~10):(1~5):(0.5~2):(0.1~1).

6. The preparation method according to claim 1, characterized in that, The metal in the metal salt solution in step (2) includes one or more of nickel, cobalt and manganese; the concentration of the metal salt solution is 0.5~2.5 mol / L.

7. The preparation method according to claim 1, characterized in that, In step (2), the flow rate of the metal salt solution is 3~8 L / h, the flow rate of the precipitant solution is 4~8 L / h, the flow rate of the complexing agent solution is 3~6 L / h, the flow rate of the buffer salt solution is 1~2 L / h, and the flow rate of the morphology modifier solution is 0.1~1 L / h.

8. The preparation method according to claim 1, characterized in that, The temperature of the co-precipitation reaction in step (2) is 45~75℃; the particle size D50 of the intermediate is 10±0.5μm.

9. The lithium-rich manganese-based carbonate precursor prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the lithium-rich manganese-based carbonate precursor of claim 9 in lithium batteries.

Images