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

Abstract

This invention belongs to the field of battery materials and discloses a lithium-rich manganese-based precursor material, its preparation method, and its applications. The molecular formula of the lithium-rich manganese-based precursor material is Mn. 1‑m‑n N n (OH)₂, wherein N is one or more of Ni, Co, Fe, Al, and Zn, m ranges from 0.1 to 0.4, and n ranges from 0 to 0.4; the lithium-rich manganese-based precursor material exhibits a mixed morphology of plate-like particles and spherical particles, wherein the plate-like particles are polygonal, and the spherical particles are distributed among the plate-like particles. The cathode material obtained after lithiation of the lithium-rich manganese-based precursor material at high temperature has good compaction and tap density, and its application in batteries can improve the electrochemical performance of the batteries.

Description

Technical Field

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

[0002] Compared to LiCoO2, metal oxide cathode materials are widely used due to their relatively low price, excellent thermal stability, and good cycle performance. Among them, the lithium-rich phase xLiMO2·(1-x)Li2MnO3 in lithium-rich xLiMO2·(1-x)Li2MnO3 materials can be regarded as a continuous solid solution formed by Li2MnO3 and LiMO2 (M represents a transition metal).

[0003] The structure of lithium-rich materials is relatively complex. During charging and discharging, the migration of lithium ions and the charge compensation mechanism not only involve changes in the bulk lattice structure, but also the interfacial reaction between the surface and the electrolyte. Furthermore, lattice oxygen (not just transition metal ions) participates in the redox reaction, resulting in a complex reaction process that occurs simultaneously in multiple regions.

[0004] In existing technologies, commonly used processes for preparing lithium-rich manganese-based cathode materials include solid-phase and liquid-phase methods. Solid-phase methods typically involve mechanically mixing raw materials followed by high-temperature calcination. During calcination, particles of uneven size (ranging from submicron to micron-sized) are easily formed, and the high temperature easily leads to particle agglomeration, destroying the sphericity and dispersibility of the particles. This results in irregular particle morphology, a wide particle size distribution, and large gaps during packing, making it difficult to reduce porosity through compaction, leading to low compaction density.

[0005] While liquid-phase methods can improve compositional uniformity, certain process details can still lead to compaction performance defects. Liquid-phase methods include co-precipitation and sol-gel methods. Co-precipitation tends to generate precursor particles with excessively small particle sizes, which easily agglomerate into loose secondary particles after calcination, or result in an excessively wide particle size distribution and an imbalance in the proportion of small particles filling the gaps between large particles, leading to decreased packing efficiency. The sol-gel method forms powder through gel drying followed by calcination. However, if the gel network is uneven, different local shrinkage rates during calcination can cause cracks or porous structures, increasing the internal porosity of the particles. During compaction, the particles are prone to breakage due to internal pores, failing to form a dense packing.

[0006] In general, existing processes for preparing lithium-rich materials tend to result in poor compaction density and energy density. Summary of the Invention

[0007] In view of the defects and deficiencies of the existing technology, the present invention provides, in a first aspect, a lithium-rich manganese-based precursor material; in a second aspect, a method for preparing the lithium-rich manganese-based precursor material; in a third aspect, a lithium-rich manganese-based cathode material; in a fourth aspect, a method for preparing the lithium-rich manganese-based cathode material; and in a fifth aspect, a battery.

[0008] In a first aspect, the present invention provides a lithium-rich manganese-based precursor material, wherein the lithium-rich manganese-based precursor material has the molecular formula Mn 1-m-n N n (OH)2, wherein N is one or more of Ni, Co, Fe, Al, and Zn, m ranges from 0.1 to 0.4, and n ranges from 0 to 0.4; the lithium-rich manganese-based precursor material has a mixed morphology of plate-like particles and quasi-spherical particles, wherein the plate-like particles are polygonal, and the quasi-spherical particles are distributed among the plate-like particles.

[0009] Preferably, the D50 of the spherical particles is 100~500nm.

[0010] Secondly, the present invention provides a method for preparing a lithium-rich manganese-based precursor material, comprising the following steps:

[0011] Step 1: Mix manganese salt, nitrogen metal salt and water to form solution A;

[0012] Step 2, First stage coprecipitation: Solution A, ammonia, additive, and sodium hydroxide solution are introduced into the reaction system respectively, and the reaction is carried out under a protective atmosphere;

[0013] Step 3, Second stage co-precipitation: Adjust the concentration of solution A, the concentration of sodium hydroxide solution, and the reaction speed, and continue to pass solution A, ammonia, sodium hydroxide, and additives into the reaction system to allow the reaction to proceed;

[0014] Step 4: Filter and dry. The resulting solid particles are the lithium-rich manganese-based precursor material.

[0015] Preferably, the manganese salt is any one or both of manganese nitrate and manganese sulfate.

[0016] Preferably, the N element in the N metal salt is any one or more of Ni, Co, Fe, Al, and Zn; the N metal salt is a nitrate or a sulfate.

[0017] Preferably, the additive is any one or more of PVP (polyvinylpyrrolidone) solution, CTAB (hexadecyltrimethylammonium bromide) solution, and SDS (sodium dodecyl sulfate) solution.

[0018] Preferably, in step 1, the molar amounts of manganese salt and N metal salt are the same as the ratio of Mn to N in the molecular formula of the lithium-rich manganese-based precursor material.

[0019] Preferably, in step 2, the concentration of solution A is 30-50 g / L; the concentration of sodium hydroxide is 40-60 g / L; the concentration of ammonia is 15-40 wt%; the concentration of additive is 50-100 g / L; the flow rate of solution A is 30-100 L / h; the flow rate of sodium hydroxide solution is 30-100 L / h; the flow rate of ammonia is 10-18 L / h; and the flow rate of additive is 10-18 L / h.

[0020] Preferably, in step 2, the reaction speed is 100~200 rpm / min, the reaction time is 2~5 h, and the reaction temperature is 35~55℃.

[0021] Preferably, in step 3, the concentration of solution A is 70-100 g / L; the concentration of sodium hydroxide is 70-100 g / L; the concentration of ammonia is 15-40 wt%; the concentration of additive is 50-100 g / L; the flow rate of solution A is 30-100 L / h; the flow rate of sodium hydroxide solution is 30-100 L / h; the flow rate of ammonia is 20-50 L / h; and the flow rate of additive is 20-40 L / h.

[0022] Preferably, in step 3, the reaction speed is 220~260 rpm / min, the reaction time is 0.5~2h, and the reaction temperature is 35~55℃.

[0023] Thirdly, the present invention provides a lithium-rich manganese-based cathode material, wherein the molecular formula of the lithium-rich manganese-based cathode material is Li. 1+m Mn 1-m-n N n O2, wherein N is one or more of Ni, Co, Fe, Al, and Zn, m ranges from 0.1 to 0.4, and n ranges from 0 to 0.4; the lithium-rich manganese-based cathode material has a mixed morphology of sheet-like and spherical shapes, the sheet-like particles are polygonal, and the spherical particles are distributed among the sheet-like particles.

[0024] Preferably, the D50 of the spherical particles is 100~500nm.

[0025] Preferably, the compaction density of the lithium-rich manganese-based cathode material is 3.0~3.8 g / cm³. 3 The tap density of the lithium-rich manganese-based cathode material is 1.5~2 g / cm³. 3 .

[0026] Fourthly, the present invention provides a method for preparing a lithium-rich manganese-based cathode material, which is obtained by mixing lithium with the above-mentioned precursor or the lithium-rich manganese-based precursor material prepared by the above-mentioned method and then calcining it in an oxygen-containing atmosphere.

[0027] Preferably, the lithium salt is any one or more of lithium carbonate, lithium nitrate, and lithium acetate.

[0028] Preferably, the molar ratio of lithium in the lithium-rich manganese-based precursor material to lithium in the lithium salt is 1:1.24~1.9.

[0029] Preferably, the calcination temperature is 900~1100℃ and the calcination time is 10~30h.

[0030] Fifthly, the present invention provides a battery comprising the above-described lithium-rich manganese-based cathode material or the lithium-rich manganese-based cathode material prepared by the above-described preparation method.

[0031] Compared with the prior art, the present invention has the following significant advantages:

[0032] (1) This invention provides a lithium-rich manganese-based precursor material with a special morphology, wherein the sheet-like material is beneficial to improving the reaction kinetics of the material, and the filling of the gaps between the sheets with spherical particles can effectively improve the volumetric energy density of the material. The cathode material obtained after lithiation of the lithium-rich manganese-based precursor material at high temperature has good compaction density and tap density. Applying the cathode material to the battery can improve the electrochemical performance of the battery.

[0033] (2) The process for preparing lithium-rich manganese-based precursor materials provided by the present invention is simple, does not require adjustment of existing production lines, and is conducive to industrialization. Attached Figure Description

[0034] Figure 1 The image shows a SEM image of the lithium-rich manganese-based cathode material prepared in Example 1 at 6000x magnification.

[0035] Figure 2 The image shows a SEM image of the lithium-rich manganese-based cathode material prepared in Example 1 at 5000x magnification.

[0036] Figure 3 SEM image of the lithium-rich manganese-based cathode material prepared in Comparative Example 1;

[0037] Figure 4 SEM image of the lithium-rich manganese-based cathode material prepared in Comparative Example 2;

[0038] Figure 5 This is a schematic diagram of the battery cycle curves assembled from the positive electrode materials prepared in Examples 1-3 and Comparative Examples 1-2. Detailed Implementation

[0039] The present invention provides the following specific technical solutions.

[0040] Firstly, the lithium-rich manganese-based precursor material has the molecular formula Mn. 1-m-n N n (OH)2, wherein N is one or more of Ni, Co, Fe, Al, and Zn, m ranges from 0.1 to 0.4, and n ranges from 0 to 0.4; the lithium-rich manganese-based precursor material has a mixed morphology of sheet-like and spherical shapes, the sheet-like particles are polygonal, and the spherical particles are distributed among the sheet-like particles.

[0041] Through research, the inventors discovered that sheet-like particles have a large two-dimensional plane, while spherical particles have a three-dimensional symmetrical structure. When the two are mixed, the spherical particles can fill the gaps between the sheet-like particles, reducing voids and gaps between particles and significantly improving the packing density of the precursor. This high packing density helps reduce the volume voids in the cathode material during subsequent sintering with the lithium source, ultimately increasing the energy density of the electrode.

[0042] The planar structure of plate-like particles provides more lithium-ion diffusion channels and shortens the ion migration path; while spherical particles have a higher specific surface area, which increases the contact area with the electrolyte and promotes ion transport. The particle structure formed by the mutual support of the two morphologies can reduce electron conduction resistance, reduce polarization, and improve the cycling stability of the material.

[0043] Spherical particles distributed between the plate-like particles act as a buffer and support, alleviating stress concentration caused by lattice expansion / contraction during charging and discharging, and reducing particle breakage or pulverization. The hierarchical porous structure formed by the mixed morphology (micropores between the plate-like gaps and spherical particles) enhances the electrolyte's permeability, making the surface of the active material easier to wet with the electrolyte and preventing capacity decay caused by excessive local reactions. The synergistic effect between particles promotes uniform lithium-ion insertion / extraction throughout the electrode, reduces local concentration gradients, lowers the probability of side reactions (such as electrolyte decomposition), and extends battery cycle life.

[0044] In summary, the hybrid morphology, through structural complementarity, balances packing density, transport kinetics, mechanical stability, and reaction uniformity, laying the foundation for high energy density, high rate performance, and long cycle life of lithium-rich manganese-based cathode materials.

[0045] Preferably, the D50 of the spherical particles is 100~500nm.

[0046] Secondly, the present invention provides a method for preparing a lithium-rich manganese-based precursor material, comprising the following steps:

[0047] Step 1: Mix manganese salt, nitrogen metal salt and water to form solution A;

[0048] Step 2, First stage coprecipitation: Solution A, ammonia, additive, and sodium hydroxide solution are introduced into the reaction system respectively, and the reaction is carried out under a protective atmosphere;

[0049] Step 3, Second stage co-precipitation: Adjust the concentration of solution A, the concentration of sodium hydroxide solution, and the reaction speed, and continue to pass solution A, ammonia, sodium hydroxide, and additives into the reaction system to allow the reaction to proceed;

[0050] Step 4: Filter and dry. The resulting solid particles are the lithium-rich manganese-based precursor material.

[0051] Through research, the inventors discovered that by controlling reaction factors such as solution concentration, reaction speed, and reaction temperature, they were able to prepare lithium-rich manganese-based cathode materials with a mixed morphology of sheet-like and near-spherical shapes using a one-step co-precipitation method combined with lithiation sintering.

[0052] Preferably, the manganese salt is any one or both of manganese nitrate and manganese sulfate.

[0053] Preferably, the N element in the N metal salt is any one or more of Ni, Co, Fe, Al, and Zn; the N metal salt is a nitrate or a sulfate.

[0054] Preferably, the additive is any one or more of PVP (polyvinylpyrrolidone) solution, CTAB (hexadecyltrimethylammonium bromide) solution, and SDS (sodium dodecyl sulfate) solution.

[0055] The additive can regulate the growth direction by adsorbing onto the particle surface. In the first stage, it may inhibit the excessive stacking of flaky particles, and in the second stage, it can stabilize the surface energy of spherical particles and promote their uniform dispersion.

[0056] Preferably, in step 1, the molar amounts of manganese salt and N metal salt are the same as the ratio of Mn to N in the molecular formula of the lithium-rich manganese-based precursor material.

[0057] Preferably, in step 2, the concentration of solution A is 30-50 g / L; the concentration of sodium hydroxide is 40-60 g / L; the concentration of ammonia is 15-40 wt%; the concentration of additive is 50-100 g / L; the flow rate of solution A is 30-100 L / h; the flow rate of sodium hydroxide solution is 30-100 L / h; the flow rate of ammonia is 10-18 L / h; and the flow rate of additive is 10-18 L / h.

[0058] Preferably, in step 2, the reaction speed is 100~200 rpm / min, the reaction time is 2~5 h, and the reaction temperature is 35~55℃.

[0059] Preferably, in step 3, the concentration of solution A is 70-100 g / L; the concentration of sodium hydroxide is 70-100 g / L; the concentration of ammonia is 15-40 wt%; the concentration of additive is 50-100 g / L; the flow rate of solution A is 30-100 L / h; the flow rate of sodium hydroxide solution is 30-100 L / h; the flow rate of ammonia is 20-50 L / h; and the flow rate of additive is 20-40 L / h.

[0060] Preferably, in step 3, the reaction speed is 220~260 rpm / min, the reaction time is 0.5~2h, and the reaction temperature is 35~55℃.

[0061] Thirdly, the present invention provides a lithium-rich manganese-based cathode material, wherein the molecular formula of the lithium-rich manganese-based cathode material is Li. 1+m Mn 1-m-n N n O2, wherein N is one or more of Ni, Co, Fe, Al, and Zn, m ranges from 0.1 to 0.4, and n ranges from 0 to 0.4; the lithium-rich manganese-based cathode material has a mixed morphology of sheet-like and spherical shapes, the sheet-like particles are polygonal, and the spherical particles are distributed among the sheet-like particles.

[0062] Preferably, the D50 of the spherical particles is 100~500nm.

[0063] Preferably, the compaction density of the lithium-rich manganese-based cathode material is 3.0~3.8 g / cm³. 3 The tap density of the lithium-rich manganese-based cathode material is 1.5~2 g / cm³. 3 .

[0064] Fourthly, the present invention provides a method for preparing a lithium-rich manganese-based cathode material, which is obtained by mixing lithium with the above-mentioned precursor or the lithium-rich manganese-based precursor material prepared by the above-mentioned method and then calcining it in an oxygen-containing atmosphere.

[0065] Preferably, the lithium salt is any one or more of lithium carbonate, lithium nitrate, and lithium acetate.

[0066] Preferably, the molar ratio of lithium in the lithium-rich manganese-based precursor material to lithium in the lithium salt is 1:1.24~1.9.

[0067] Preferably, the calcination temperature is 900~1100℃ and the calcination time is 10~30h.

[0068] Fifthly, the present invention provides a battery comprising the above-described lithium-rich manganese-based cathode material or the lithium-rich manganese-based cathode material prepared by the above-described preparation method.

[0069] To make the technical problems, technical solutions and technical advantages of the present invention clearer, a detailed description will be given below with reference to specific examples. However, the scope of protection of the present invention is not limited to the following specific embodiments.

[0070] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0071] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0072] Example 1:

[0073] A method for preparing a lithium-rich manganese-based cathode material includes the following steps:

[0074] Step 1: Dissolve MnSO4·H2O and CoSO4·6H2O in deionized water at a molar ratio of 2:1 to prepare solution A with a concentration of 40 g / L and solution B with a concentration of 80 g / L.

[0075] Step 2: Solution A, 35wt% ammonia, 60g / L SDS solution, and 50g / L sodium hydroxide solution are respectively introduced into a continuous stirred tank reactor. The flow rates of solution A and sodium hydroxide are both 40L / h, and the flow rates of ammonia and SDS solution are both 15L / h. The reaction speed is 140rpm / min, and the reaction is carried out at 40℃ for 4h under nitrogen atmosphere protection.

[0076] Step 3: Stop the flow of solution A and the 50 g / L sodium hydroxide solution. Adjust the flow to solution B and the 100 g / L sodium hydroxide solution, with both solutions B and sodium hydroxide flowing at a rate of 40 L / h. Continue the flow of ammonia and SDS solution, with both flowing at a rate of 30 L / h. Adjust the reaction speed to 220 rpm / min, react at 40°C for 1 hour, then filter and dry. The resulting solid particles are Mn. 0.67 Co 0.33 (OH)2 precursor.

[0077] Step 4, take 0.1 mol of Mn 0.67 Co 0.33 After mechanically mixing (OH)₂ with 0.124 mol of lithium hydroxide, the mixture was sintered at 980 °C for 20 h in a muffle furnace, ultimately yielding Li₂ with a mixed morphology of flakes and spherical shapes. 1.1 Mn 0.6 Co 0.3 O2.

[0078] Comparative Example 1:

[0079] A method for preparing a lithium-rich manganese-based cathode material includes the following steps:

[0080] Step 1: Dissolve MnSO4·H2O and CoSO4·6H2O in deionized water at a molar ratio of 2:1 to prepare solution A with a concentration of 40 g / L and solution B with a concentration of 80 g / L.

[0081] Step 2: Solution A, 35wt% ammonia, 60g / L SDS solution, and 50g / L sodium hydroxide solution were separately introduced into a continuous stirred tank reactor. The flow rates of solution A and sodium hydroxide were both 40L / h, while the flow rates of ammonia and SDS solution were both 15L / h. The reaction speed was 140rpm / min. After reacting at 40℃ for 4 hours under a nitrogen atmosphere, the mixture was filtered and dried. The resulting solid particles were Mn. 0.67 Co 0.33 (OH)2 precursor.

[0082] Step 3, take 0.1 mol of Mn 0.67 Co 0.33 (OH)₂ was mechanically mixed with 0.124 mol of lithium hydroxide and then sintered at 980 °C for 20 h in a muffle furnace to obtain Li₂ with a plate-like morphology. 1.1 Mn 0.6 Co 0.3 O2.

[0083] Comparative Example 2:

[0084] A method for preparing a lithium-rich manganese-based cathode material includes the following steps:

[0085] Step 1: Dissolve MnSO4·H2O and CoSO4·6H2O in deionized water at a molar ratio of 2:1 to prepare solution A with a concentration of 40 g / L and solution B with a concentration of 80 g / L.

[0086] Step 2: Solution A, 35wt% ammonia, 60g / L SDS solution, and 50g / L sodium hydroxide solution were separately introduced into a continuous stirred tank reactor. The flow rates of solution A and sodium hydroxide were both 40L / h, and the flow rates of ammonia and SDS solution were both 30L / h. The reaction speed was 20rpm / min. After reacting at 40℃ for 1 hour under a nitrogen atmosphere, the mixture was filtered and dried. The resulting solid particles were Mn. 0.67 Co 0.33 (OH)2 precursor.

[0087] Step 3, take 0.1 mol of Mn 0.67 Co 0.33(OH)₂ was mechanically mixed with 0.062 mol of lithium carbonate and then sintered at 980 °C for 20 h in a muffle furnace to obtain Li₂ with a spherical morphology. 1.1 Mn 0.6 Co 0.3 O2.

[0088] Example 2:

[0089] A method for preparing a lithium-rich manganese-based cathode material includes the following steps:

[0090] Step 1: Dissolve MnSO4·H2O and FeSO4·6H2O in deionized water at a molar ratio of 3:1 to prepare solution A with a concentration of 30 g / L and solution B with a concentration of 70 g / L.

[0091] Step 2: Solution A, 15wt% ammonia, 50g / L CTAB solution, and 40g / L sodium hydroxide solution are respectively introduced into a continuous stirred tank reactor. The flow rates of solution A and sodium hydroxide are both 30L / h, and the flow rates of ammonia and CTAB solution are both 10L / h. The reaction speed is 110Hz, and the reaction is carried out at 40℃ for 5h under nitrogen atmosphere protection.

[0092] Step 3: Stop the flow of solution A and the 40 g / L sodium hydroxide solution. Adjust the flow to solution B and the 70 g / L sodium hydroxide solution, with both solutions B and sodium hydroxide flowing at a rate of 30 L / h. Continue the flow of ammonia and CTAB solution, with both flowing at a rate of 20 L / h. Adjust the reaction speed to 260 Hz, react at 40°C for 2 hours, then filter and dry. The resulting solid particles are Mn. 0.75 Fe 0.25 (OH)2 precursor.

[0093] Step 4, take 0.1 mol of Mn 0.75 Fe 0.25 After mechanically mixing (OH)₂ with 0.154 mol of lithium nitrate, the mixture was sintered at 900℃ for 30 h in a muffle furnace, ultimately yielding Li₂ with a mixed morphology of flakes and spherical shapes. 1.2 Mn 0.6 F e0.2 O2.

[0094] Example 3:

[0095] A method for preparing a lithium-rich manganese-based cathode material includes the following steps:

[0096] Step 1: Dissolve MnSO4·H2O and ZnSO4·6H2O in deionized water at a molar ratio of 5:1 to prepare solution A with a concentration of 50 g / L and solution B with a concentration of 100 g / L.

[0097] Step 2: Solution A, 40wt% ammonia, 100g / L PVP solution, and 60g / L sodium hydroxide solution are respectively introduced into a continuous stirred tank reactor. The flow rates of solution A and sodium hydroxide are 100L / h, and the flow rates of ammonia and PVP solution are 18L / h. The reaction speed is 160Hz, and the reaction is carried out at 40℃ for 2h under nitrogen atmosphere protection.

[0098] Step 3: Stop the flow of solution A and the 60 g / L sodium hydroxide solution. Adjust the flow to solution B and the 100 g / L sodium hydroxide solution, with both solutions B and sodium hydroxide flowing at a rate of 100 L / h. Continue the flow of ammonia and PVP solution, with both flowing at a rate of 36 L / h. Adjust the reaction speed to 250 Hz, react at 40°C for 0.5 h, then filter and dry. The resulting solid particles are Mn. 0.83 Zn 0.17 (OH)2 precursor.

[0099] Step 4, take 0.1 mol of Mn 0.83 Zn 0.17 After mechanically mixing (OH)₂ with 0.19 mol of lithium acetate, the mixture was sintered at 1100 °C for 10 h in a muffle furnace to obtain Li₂ with a mixed morphology of flakes and spherical shapes. 1.3 Mn 0.58 Zn 0.12 O2.

[0100] Figure 1 This is a SEM image of the lithium-rich manganese-based cathode material prepared in Example 1, magnified 6000 times. Figure 2 This is a SEM image of the lithium-rich manganese-based cathode material prepared in Example 1 at 5000x magnification; Figure 1 and Figure 2 It can be seen that the particles have a mixed morphology of plate-like and spherical shapes, and the spherical particles fill the spaces between the plate-like particles, resulting in a high degree of compact packing.

[0101] Figure 3 The image shows a SEM image of the lithium-rich manganese-based cathode material prepared in Comparative Example 1. Figure 3 It can be seen that the particles are in the form of flakes, and there are certain gaps between the stacked flake particles.

[0102] Figure 4 The image shows a SEM image of the lithium-rich manganese-based cathode material prepared in Comparative Example 2. Figure 4 It can be seen that the particles are basically spherical or near-spherical, and the particle aggregation is serious.

[0103] The tap density and compaction density of the lithium-rich manganese-based cathode materials prepared in Examples 1-3 and Comparative Examples 1-2 were tested. For the tap density test, the powder was allowed to settle naturally through mechanical vibration; compaction density is the density of the powder after compression under specific pressure. The test results are shown in Table 1.

[0104] Table 1. Tap density and compaction density of lithium-rich manganese-based cathode materials prepared in Examples 1-3 and Comparative Examples 1-2

[0105]

[0106] As can be seen from Table 1, the tap density and compaction density of the mixed-morphology cathode material prepared by the preparation process provided by the present invention are greater than those of the cathode materials prepared by Comparative Examples 1 and 2. Figure 3 and Figure 4 The inventors propose that: The single-sheet cathode material obtained in Comparative Example 1 easily forms overlapping, interlacing, and suspended structures during stacking. Even with vibration or pressure, a large number of wedge-shaped or interlayer voids remain between the sheets, significantly increasing the overall porosity and resulting in low tap density and compaction density. The spherical or near-spherical cathode material obtained in Comparative Example 2 suffers from uneven particle size distribution due to partial particle agglomeration, leading to significant size differences, increased porosity, and reduced particle filling efficiency and densification ability under vibration or pressure, thus affecting the material's tap density and compaction density. In contrast, the cathode material with a mixed morphology of sheet and near-spherical shapes provided by this invention exhibits strong structural continuity, resulting in superior tap density and compaction density. It can be predicted that the conductivity and ion transport performance of the mixed morphology cathode material are more stable, demonstrating excellent electrochemical stability.

[0107] The cathode materials obtained in Examples 1-3 and Comparative Examples 1-2 were used to assemble batteries using the following method:

[0108] The positive electrode materials prepared in Examples 1-3 and Comparative Examples 1-2 were weighed and ground according to a mass ratio of positive electrode material: conductive graphite: PVDF of 8:1:1. Then, an appropriate amount of N-methylpyrrolidone (NMP) was added, and grinding and stirring were continued to form a uniform slurry. The slurry was then uniformly coated onto aluminum foil using a mold to a thickness of 200 μm, and placed in a drying oven at 90°C for 10 hours. The coated foil was then cut into 12 mm diameter discs. Using the discs as the positive electrode and lithium foil as the negative electrode, the electrolyte consisted of a solvent and LiPF6, with a LiPF6 concentration of 1 mol / L. The electrolyte solvent was a mixture of EC, DEC, and DMC in a volume ratio of 1:1:1. The batteries were assembled in a glove box according to the coin cell assembly sequence. The assembled batteries were subjected to performance testing. After being left to stand overnight, the assembled batteries were placed in the LAND2001CT battery test chamber for charge and discharge testing. The test was conducted at 25°C, 1C, and a cycle voltage of 2.8~4.8V, with 100 cycles.

[0109] Figure 5 This is a schematic diagram of the cycle curves of batteries assembled from the cathode materials prepared in Examples 1-3 and Comparative Examples 1-2. Figure 5 It can be seen that the cathode material provided by the present invention has superior cycle performance and chemical stability, and it can be reasonably predicted that the cathode material with a mixed morphology of sheet and quasi-spherical shape provided by the present invention has a longer service life.

[0110] The above-described embodiments are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope of the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A lithium-rich manganese-based precursor material, characterized in that, The lithium-rich manganese-based precursor material has a molecular formula of Mn 1-m-n N n (OH)2, wherein N is one or two or more of Ni, Co, Fe, Al, and Zn, m is in a range of 0.1<=m<=0.4, and n is in a range of 0<=n<=0.4; the lithium-rich manganese-based precursor material has a mixed morphology of flaky particles and spherical-like particles, the flaky particles are polygonal, and the spherical-like particles are distributed between the flaky particles.

2. The lithium-rich manganese-based precursor material as described in claim 1, characterized in that, The D50 of the spherical particles is 100~500nm.

3. A method for preparing a lithium-rich manganese-based precursor material, characterized in that, Includes the following steps: Step 1: Mix manganese salt, nitrogen metal salt and water to form solution A and solution B. The concentration of metal element in solution A is lower than that in solution B. Step 2, First stage coprecipitation: Solution A, ammonia, additive, and sodium hydroxide solution are introduced into the reaction system separately and reacted under a protective atmosphere; the reaction speed is 100~200 rpm; Step 3, second stage coprecipitation: Stop the flow of solution A, adjust the reaction speed, and introduce solution B, ammonia, sodium hydroxide, and additives into the reaction system. React under a protective atmosphere; the reaction speed is 220~260 rpm. Step 4: Filter and dry. The resulting solid particles are the lithium-rich manganese-based precursor material. The additive is any one or more of PVP solution, CTAB solution, and SDS solution; the additive concentration is 50~100g / L; in step 2, the flow rate of the additive is 10~18L / h; in step 3, the flow rate of the additive is 20~40L / h.

4. The method for preparing the lithium-rich manganese-based precursor material as described in claim 3, characterized in that, The manganese salt is any one or two of manganese nitrate and manganese sulfate; the N element in the N metal salt is any one or more of Ni, Co, Fe, Al, and Zn; the N metal salt is a nitrate or a sulfate; in step 1, the molar amounts of manganese in the manganese salt and N in the N metal salt are the same as the ratio of Mn to N in the molecular formula of the lithium-rich manganese-based precursor material.

5. The method for preparing the lithium-rich manganese-based precursor material as described in claim 3, characterized in that, In step 2, the reaction time is 2-5 hours and the reaction temperature is 35-55°C; in step 3, the reaction time is 0.5-2 hours and the reaction temperature is 35-55°C.

6. The method for preparing the lithium-rich manganese-based precursor material as described in claim 3, characterized in that, In step 2, the concentration of solution A is 30-50 g / L; the concentration of sodium hydroxide is 40-60 g / L; the concentration of ammonia is 15-40 wt%; the flow rate of solution A is 30-100 L / h; the flow rate of sodium hydroxide solution is 30-100 L / h; and the flow rate of ammonia is 10-18 L / h. In step 3, the concentration of solution B is 70~100g / L; the concentration of sodium hydroxide is 70~100g / L; the concentration of ammonia is 15~40wt%; the concentration of additive is 50~100g / L; the flow rate of solution B is 30~100L / h; the flow rate of sodium hydroxide solution is 30~100L / h; and the flow rate of ammonia is 20~50L / h.

7. A lithium-rich manganese-based cathode material, characterized in that, The molecular formula of the lithium-rich manganese-based cathode material is Li. 1+m Mn 1-m- n N n O2, wherein N is one or more of Ni, Co, Fe, Al, and Zn, m ranges from 0.1 to 0.4, and n ranges from 0 to 0.4; the morphology of the lithium-rich manganese-based cathode material is a mixture of sheet-like particles and quasi-spherical particles, wherein the sheet-like particles are polygonal, and the quasi-spherical particles are distributed among the sheet-like particles.

8. The lithium-rich manganese-based cathode material as described in claim 7, characterized in that, The spherical particles have a D50 of 100~500nm; the lithium-rich manganese-based cathode material has a compaction density of 3.0~3.8g / cm³. 3 The tap density of the lithium-rich manganese-based cathode material is 1.5~2 g / cm³. 3 .

9. A method for preparing a lithium-rich manganese-based cathode material, characterized in that, The precursor material prepared by any one of the lithium-rich manganese-based precursor materials according to claims 1 to 2 or by any one of the preparation methods according to claims 3 to 6 is calcined under an oxygen-containing atmosphere after being mixed with lithium.

10. A battery, characterized in that, This includes the lithium-rich manganese-based cathode material according to any one of claims 7 to 8 or the lithium-rich manganese-based cathode material prepared by the preparation method according to claim 9.

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