Lithium-rich manganese-based positive electrode material precursor particle as well as preparation method and application thereof

Abstract

The invention discloses lithium-rich manganese-based positive electrode material precursor particles as well as a preparation method and application thereof, and relates to the technical field of lithium batteries. The lithium-rich manganese-based positive electrode material precursor particles provided by the invention have the characteristics of high degree of sphericity, thin primary particles, uniform thickness and uniform surface pore distribution, the tap density of the positive electrode material is favorably improved, a lithium ion transmission channel is provided by utilizing surface pores, and the rate capability of the positive electrode material is favorably improved. By optimizing the preparation process of the lithium-rich manganese-based positive electrode material precursor particles, the high rotating speed is maintained in the synthesis process to enhance the dispersity, and by matching with the specific reaction atmosphere, the agglomeration effect can be weakened, the sphericity and TD of the particles are improved, and the agglomeration problem of the lithium-rich manganese-based positive electrode material precursor material in the synthesis process is solved.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and more specifically, to lithium-rich manganese-based cathode material precursor particles, their preparation methods, and applications. Background Technology

[0002] Lithium-rich manganese-based cathode materials possess significant advantages such as high specific capacity and low cost, and are considered to be the next generation of high-capacity battery cathode materials. The hydroxide co-precipitation method is currently the mainstream method for preparing lithium-rich manganese precursors. Specifically, a metal sulfate solution, a hydroxide precipitant, and a complexing agent are mixed and placed in a reactor with a bottom liquid. The mixture is reacted at a certain temperature, with air or nitrogen purging during the reaction. After the reaction, the materials are washed, dried, and packaged sequentially to obtain spherical lithium-rich manganese precursor materials. However, with increasing manganese content, the agglomeration problem of small-particle lithium-rich manganese precursors becomes severe, resulting in poor morphological uniformity and sphericity, which is detrimental to improving tap density and also affects the capacity performance of the cathode material.

[0003] To address the aggregation problem, existing technologies have employed various methods, but none have been able to produce lithium-rich manganese-based cathode material precursor particles that meet the requirements of high sphericity, thin and uniform primary particle thickness, and uniform surface pore distribution.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide lithium-rich manganese-based cathode material precursor particles, their preparation method and application, aiming to provide lithium-rich manganese-based cathode material precursor small particles that meet the requirements of high sphericity, thin and uniform primary particle thickness, and uniform surface pore distribution, thereby improving the electrochemical performance of cathode materials.

[0006] This invention is implemented as follows:

[0007] In a first aspect, the present invention provides lithium-rich manganese-based cathode material precursor particles, the chemical formula of which is Ni a Mn b M c (OH)2, wherein 0.1≤a≤0.4, 0.5≤b≤0.9, 0≤c≤0.2, a+b+c=1, and M is selected from at least one of Co, Fe, Cr, Cu, Ti, Mg, W, Mo, Nb, Ca, Zn, Sn, Zr, Al, B, Si, and P;

[0008] The lithium-rich manganese-based cathode material precursor particles are secondary particles formed by the agglomeration of primary particles. The primary particles are thin sheet-like structures with a thickness of 10nm to 120nm, where the thickness difference between the thickest and thinnest parts is ≤40nm. The sphericity of the lithium-rich manganese-based cathode material precursor particles is 0.95 to 0.98, and the pore size on the surface of the secondary particles is 30nm to 200nm.

[0009] In an optional implementation, the chemical formula satisfies: 0.2≤a≤0.35, 0.65≤b≤0.75, 0≤c≤0.1, a+b+c=1;

[0010] Preferably, the primary particles are sheet-like structures with a thickness of 20 nm to 60 nm;

[0011] Preferably, the sphericity of the lithium-rich manganese-based cathode material precursor particles is 0.96 to 0.97;

[0012] Preferably, the pore size on the surface of the secondary particles is 40 nm to 130 nm;

[0013] Preferably, the porosity inside the secondary particles is 5% to 10%, more preferably 6% to 8%.

[0014] In an optional embodiment, the particle size D50 of the lithium-rich manganese-based cathode material precursor particles is 2 μm to 5 μm, preferably 3 μm to 4 μm;

[0015] Preferably, the specific surface area of ​​the lithium-rich manganese-based cathode material precursor particles is 25 m². 2 / g~40m 2 / g, more preferably 29m 2 / g~36m 2 / g;

[0016] Preferably, the tap density of the lithium-rich manganese-based cathode material precursor particles is 1.5 g / cm³. 3 ~1.7g / cm 3 More preferably 1.55 g / cm³ 3 ~1.65g / cm 3 .

[0017] Secondly, the present invention provides a method for preparing lithium-rich manganese-based cathode material precursor particles according to any of the foregoing embodiments, comprising:

[0018] The metal salt solution, precipitant solution, and complexing agent solution are introduced into the bottom liquid of the reactor to carry out the nucleation reaction first and then the growth reaction, until the particle D50 in the slurry reaches the target particle size, and then the reaction is stopped.

[0019] During the nucleation and growth reactions, the reaction atmosphere includes air and nitrogen, with a volume ratio of 15% to 30%, and the reaction speed is 350 rpm to 550 rpm.

[0020] In an optional embodiment, during the nucleation and growth reactions, the volume ratio of air to nitrogen in the reaction atmosphere is 18% to 25%, and the reaction speed is 450 rpm to 500 rpm.

[0021] Preferably, the reaction temperature is 40℃~70℃, more preferably 50℃~65℃.

[0022] In an optional embodiment, the metal salt solution is a sulfate solution with a total metal concentration of 1.5 mol / L to 2.5 mol / L;

[0023] Preferably, the precipitant solution is an alkaline solution with a concentration of 8 mol / L to 12 mol / L;

[0024] Preferably, the complexing agent solution is ammonia solution with a concentration of 4 mol / L to 8 mol / L;

[0025] Preferably, the base solution is a mixture of liquid alkali and ammonia water, and the pH value of the base solution is 11.8 to 12.3, more preferably 11.9 to 12.2; the ammonia value of the base solution is 0.5 g / L to 5 g / L, more preferably 0.5 g / L to 3 g / L.

[0026] Preferably, the metal salt solution contains nickel, manganese, and a soluble salt corresponding to element M, wherein the soluble salt includes at least one of nitrate, chloride, and sulfate.

[0027] In an optional embodiment, the nucleation reaction time is 10 min to 200 min, preferably 30 min to 100 min;

[0028] Preferably, the pH value of the growth reaction is 8 to 10.5, more preferably 8.5 to 10;

[0029] Preferably, the ammonia value of the growth reaction is 0.5 g / L to 5 g / L, more preferably 0.5 g / L to 2 g / L;

[0030] Preferably, the reaction time for the growth reaction is 50h to 120h, more preferably 60h to 100h.

[0031] In an optional embodiment, the method further includes washing and drying the slurry obtained after the reaction;

[0032] Preferably, the washing process includes sequential alkaline washing and water washing; more preferably, the alkaline washing temperature is 50°C to 80°C, and the water washing temperature is 50°C to 80°C.

[0033] Preferably, the drying temperature is 80℃~120℃ and the drying time is 5h~12h.

[0034] Thirdly, the present invention provides a lithium-rich manganese-based cathode material, which is prepared by any of the lithium-rich manganese-based cathode material precursor particles in the foregoing embodiments or by any of the preparation methods in the foregoing embodiments and a lithium source.

[0035] Fourthly, the present invention provides a lithium battery comprising the lithium-rich manganese-based cathode material of the aforementioned embodiments.

[0036] The present invention has the following beneficial effects: The lithium-rich manganese-based cathode material precursor particles provided by the present invention have the characteristics of high sphericity, thin and uniform primary particles, and uniform surface pore distribution, which is conducive to improving the tap density of the cathode material. The surface pores provide lithium ion transport channels, which is conducive to improving the rate performance of the cathode material.

[0037] It should be added that this invention optimizes the preparation process of lithium-rich manganese-based cathode material precursor particles, maintains a high rotation speed during synthesis to enhance dispersibility, and, in conjunction with a specific reaction atmosphere, can weaken agglomeration, improve particle sphericity and TD, and solve the agglomeration problem of lithium-rich manganese-based cathode material precursor materials during synthesis. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 SEM image of the precursor particles prepared in Example 1 (magnification: 30,000x);

[0040] Figure 2 SEM image of the precursor particles prepared in Example 2 (magnification: 30,000x);

[0041] Figure 3 SEM image of the precursor particles prepared in Example 3 (magnification: 30,000x);

[0042] Figure 4 SEM image of the precursor particles prepared in Comparative Example 1 (magnification: 30,000x);

[0043] Figure 5SEM image of the precursor particles prepared in Comparative Example 2 (magnification: 30,000x). Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0045] This invention provides a lithium-rich manganese-based cathode material precursor particle with the chemical formula Ni. a Mn b M c (OH)₂, wherein 0.1≤a≤0.4, 0.5≤b≤0.9, 0≤c≤0.2, a+b+c=1, and M is selected from at least one of Co, Fe, Cr, Cu, Ti, Mg, W, Mo, Nb, Ca, Zn, Sn, Zr, Al, B, Si, and P, preferably 0.2≤a≤0.35, 0.65≤b≤0.75, 0≤c≤0.1, and a+b+c=1. The molar ratio of the metal elements is preferably within the above range.

[0046] Specifically, in the chemical formula of the lithium-rich manganese-based cathode material precursor particles, the value of a can be 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, etc.; the value of b can be 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, etc.; and the value of c can be 0.00, 0.05, 0.10, 0.15, 0.20, etc.

[0047] The lithium-rich manganese-based cathode material precursor particles are secondary particles formed by the agglomeration of primary particles. The primary particles have a thin-film structure, which is beneficial for obtaining a higher tap density in the cathode material. The thickness of the thin-film structure is 10nm to 120nm (e.g., 10nm, 20nm, 40nm, 60nm, 80nm, 100nm, 120nm, etc.), preferably 20nm to 60nm, where the thickness difference between the thickest and thinnest points is ≤40nm. The sphericity of the lithium-rich manganese-based cathode material precursor particles is 0.95 to 0.98 (e.g., 0.95, 0.96, 0.97, 0.98, etc.), preferably 0.96 to 0.97. The pore size on the surface of the secondary particles is 30nm to 200nm (e.g., 30nm, 40nm, 50nm, 80nm, 100nm, 130nm, 150nm, 180nm, 200nm, etc.), preferably 40nm to 130nm. The lithium-rich manganese-based cathode material precursor particles provided in this embodiment of the invention have the characteristics of high sphericity, thin and uniform primary particles, and uniform surface pore distribution, which is beneficial for achieving higher rate performance in the cathode material.

[0048] Specifically, the pore size on the surface of secondary particles refers to the "pore size" as traditionally understood.

[0049] Furthermore, the porosity inside the secondary particles is 5% to 10% (e.g., 5%, 6%, 7%, 8%, 9%, 10%, etc.), preferably 6% to 8%. Within this porosity range, internal lithium-ion transport channels can be provided, thereby improving the rate performance of the material.

[0050] Furthermore, the particle size D50 of the lithium-rich manganese-based cathode material precursor particles is 2 μm to 5 μm, such as 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, 5.0 μm, etc., preferably 3 μm to 4 μm. The specific surface area (BET) of the lithium-rich manganese-based cathode material precursor particles is 25 m². 2 / g~40m 2 / g, such as 25m 2 / g、28m 2 / g、30m 2 / g、32m 2 / g、34m 2 / g、36m 2 / g、38m 2 / g、39m 2 / g、40m 2 / g, etc., with a preferred BET of 29m. 2 / g~36m 2 The tap density (TD) of the lithium-rich manganese-based cathode material precursor particles is 1.5 g / cm³.3 ~1.7g / cm 3 For example, it can be 1.5g / cm 3、 1.55g / cm 3 1.58g / cm 3 1.60g / cm 3 1.66 g / cm 3 1.7g / cm 3 The preferred TD value is 1.55 g / cm³. 3 ~1.65g / cm 3 .

[0051] It should be noted that the lithium-rich manganese-based cathode material precursor particles provided in the embodiments of the present invention have uniform morphology, large specific surface area and large tap density, which is beneficial to improving the electrochemical performance of the cathode material.

[0052] It should be added that the lithium-rich manganese-based cathode material precursor particles provided in the embodiments of the present invention have the advantages of high sphericity and high TD, which can improve the compaction density of the cathode material and is beneficial to the energy density of the cathode material. The lithium-rich manganese-based cathode material precursor particles provided in the embodiments of the present invention also have the advantages of thin and uniform primary particle shape, uniform surface pore distribution, and high BET, which can be fully sintered with the lithium source and can provide more lithium ion transport channels, thereby improving the rate performance of the cathode material.

[0053] This invention also provides a method for preparing lithium-rich manganese-based cathode material precursor particles. Maintaining a high rotation speed during synthesis enhances dispersibility, and using a specific reaction atmosphere weakens agglomeration, improving particle sphericity, TD, and BET. This solves the agglomeration problem of lithium-rich manganese-based cathode material precursor materials during synthesis, and is beneficial to the dual performance of the cathode material in terms of energy density and rate capability. The steps are as follows:

[0054] S1. Prepare the reaction solution and base liquid.

[0055] A base solution is prepared in the reaction vessel. To meet the co-precipitation requirements, the base solution contains a precipitant and a complexing agent. In actual operation, a precipitant solution and a complexing agent solution can be prepared first, and then the precipitant solution and the complexing agent solution can be mixed to prepare the base solution.

[0056] In some embodiments, the precipitant solution can be an alkaline solution with a concentration of 8 mol / L to 12 mol / L, which can be a sodium hydroxide solution, but is not limited thereto. The concentration of the alkaline solution can be 8 mol / L, 9 mol / L, 10 mol / L, 11 mol / L, 12 mol / L, etc. The complexing agent solution can be ammonia water with a concentration of 4 mol / L to 8 mol / L, but is not limited thereto. The concentration of the ammonia water can be 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, etc.

[0057] Furthermore, the base solution is a mixture of liquid alkali and ammonia water, with a pH value of 11.8–12.3, such as 11.8, 11.9, 12.0, 12.1, 12.2, 12.3, etc., preferably 11.9–12.2 to meet the pH requirements of the nucleation stage. The ammonia value of the base solution is 0.5 g / L–5 g / L, such as 0.5, 1, 2, 3, 4, 5 g / L, etc., preferably 0.5–3 g / L.

[0058] A metal salt solution is prepared such that the molar ratio of the metal elements in the solution meets the requirements of the molar ratio in the chemical formula. In some embodiments, the metal salt solution comprises nickel salt, manganese salt, and soluble salts of other dopant elements M, wherein the soluble salts include at least one selected from nitrates, chlorides, and sulfates. In some embodiments, the metal salt solution can be a sulfate solution, and the total metal concentration in the sulfate solution is 1.5 mol / L to 2.5 mol / L, such as 1.5 mol / L, 1.8 mol / L, 2.0 mol / L, 2.3 mol / L, 2.5 mol / L, etc.

[0059] S2, nucleation reaction, growth reaction

[0060] A metal salt solution, a precipitant solution, and a complexing agent solution are introduced into the bottom liquid of the reactor to initiate a nucleation reaction, forming precursor core particles. These particles then undergo a growth reaction to continue growing to the target particle size. During both the nucleation and growth reactions, a constant temperature, a specific atmosphere, and a controlled stirring speed are maintained until the slurry particle size distribution (D50) reaches the target size, at which point the reaction is stopped.

[0061] In some embodiments, "isothermal state" during the nucleation and growth reactions refers to controlling the reaction temperature to 40°C to 70°C, preferably 50°C to 65°C, within which deposition is beneficial for obtaining uniform precursor particles. Specifically, the reaction temperature can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, etc.

[0062] In some embodiments, during the nucleation and growth reactions, the reaction atmosphere includes air and nitrogen, and the volume ratio of air to nitrogen is 15%–30% (e.g., 15%, 20%, 25%, 30%, etc.), preferably 18%–25%. In this embodiment of the invention, an appropriate air / nitrogen ratio is used in conjunction with the ammonia value of the reaction (specific ammonia value is described below) to ensure that the primary particles are thin and uniform in thickness, with uniform surface pore distribution, achieving a BET of 25–40 μm. 2 / g.

[0063] In some embodiments, during the nucleation and growth reactions, the reaction speed is 350 rpm to 550 rpm, such as 350 rpm, 400 rpm, 450 rpm, 480 rpm, 500 rpm, 550 rpm, etc., with a preferred reaction speed of 450 rpm to 500 rpm. At this reaction speed, the dispersion effect is enhanced, and the aggregation effect is weakened.

[0064] In some embodiments, the nucleation reaction time is 10 min to 200 min, such as 10 min, 30 min, 50 min, 80 min, 100 min, 130 min, 150 min, 180 min, 200 min, etc., preferably 30 min to 100 min. During the reaction, the pH value of the reaction system is adjusted to 11.8 to 12.3 and the ammonia value is 0.5 g / L to 5 g / L by controlling the introduction rate of the precipitant solution and the complexing agent solution.

[0065] In some embodiments, the pH value of the growth reaction is 8–10.5, such as 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, etc., preferably 8.5–10. The ammonia value of the growth reaction is 0.5 g / L–5 g / L, such as 0.5 g / L, 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, etc., preferably 0.5 g / L–2 g / L. The reaction time of the growth reaction is 50 h–120 h, such as 50 h, 60 h, 70 h, 80 h, 90 h, 100 h, 110 h, 120 h, etc., preferably 60 h–100 h. By optimizing the reaction parameters of the growth reaction stage to make the particles grow at a uniform rate, the reaction is stopped after the target particle size is obtained.

[0066] S3. Washing and drying

[0067] The slurry obtained after the reaction is washed and dried. Washing removes unreacted impurities from the particle surface, and drying removes the washing solvent.

[0068] In some embodiments, washing includes sequential alkaline washing and water washing to improve the removal efficiency of surface impurity ions. The alkaline washing solution can be a reaction alkaline solution, with a volume of 300L-500L, and a washing temperature of 50℃-80℃ (e.g., 50℃, 60℃, 70℃, 80℃, etc.). The water volume for the water washing process can be 2000L-3000L, and the washing temperature is 50℃-80℃ (e.g., 50℃, 60℃, 70℃, 80℃, etc.).

[0069] In some embodiments, the drying temperature is 80℃~120℃ (e.g., 80℃, 90℃, 100℃, 110℃, 120℃, etc.), and the drying time is 5h~12h (e.g., 5h, 8h, 10h, 12h, etc.) to fully remove the surface washing water.

[0070] This invention also provides a lithium-rich manganese-based cathode material, prepared from lithium-rich manganese-based cathode material precursor particles and a lithium source. Because the lithium-rich manganese-based cathode material precursor particles provided in this invention combine the advantages of high sphericity, high TD (thermal density), primary particle morphology, and surface porosity distribution, they are beneficial to the dual performance of the cathode material in terms of energy density and rate capability.

[0071] This invention also provides a lithium battery, including the lithium-rich manganese-based cathode material provided in this invention, which is beneficial for improving the energy density and rate performance of the lithium battery.

[0072] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0073] Example 1

[0074] This embodiment provides a method for preparing lithium-rich manganese-based cathode material precursor particles, the steps of which are as follows:

[0075] Prepare a metal sulfate solution with a total metal concentration of 2.2 mol / L (the metal sulfate solution includes nickel sulfate and manganese sulfate, with a nickel-manganese molar ratio of 35:65, the same below), an alkali solution (sodium hydroxide solution, the same below) with a concentration of 8.5 mol / L, and an ammonia solution with a concentration of 6 mol / L. Mix the alkali solution and the ammonia solution to prepare a bottom solution with a pH of 12.1 and an ammonia concentration of 0.5 g / L in a reaction vessel.

[0076] Metal sulfate solution, alkaline solution, and ammonia were added to the base solution for reaction. The nucleation reaction time was 80 min. During the reaction, the pH value in the reactor was controlled at 12.1, the ammonia value at 0.5 g / L, the reaction temperature at 60℃, and the stirring speed at 500 rpm. After the nucleation reaction was completed, the growth reaction continued. The growth reaction was carried out at pH 9.5, the ammonia value at 0.5 g / L, the reaction temperature at 60℃, the atmosphere composition at air / nitrogen = 15% (volume ratio, the same below), the stirring speed at 450 rpm, the target particle size at 4 μm, and the growth reaction time at 83 h. The slurry prepared by the reaction was first washed with 400 L of alkali (alkali washing temperature at 75℃, the same below) and 2800 L of water (water washing temperature at 75℃, the same below). Then it was dried at 100℃ for 8 h. After drying, small particles of lithium-rich manganese-based cathode material precursor were obtained.

[0077] The precursor particles were analyzed by primary particle thickness, secondary particle surface pore size, secondary particle internal porosity, particle size D50, sphericity, BET, and TD tests. The results are shown in Table 1.

[0078] SEM tests were performed on the precursor particles, and the results are shown in the attached figure. Figure 1 As can be seen, the precursor particles of the lithium-rich manganese-based cathode material prepared in this embodiment have a particle size of 4.00 μm and a primary particle thickness of 30–50 nm.

[0079] Example 2

[0080] This embodiment provides a method for preparing lithium-rich manganese-based cathode material precursor particles, the steps of which are as follows:

[0081] Prepare a 2.2 mol / L metal sulfate solution, an 8.5 mol / L alkali solution, and a 6 mol / L ammonia solution. Mix the alkali solution and ammonia solution to prepare a base solution with a pH of 12.1 and an ammonia concentration of 1 g / L in a reaction vessel.

[0082] Metal sulfate solution, alkaline solution, and ammonia were added to the base solution for reaction. The nucleation reaction time was 75 min. During the reaction, the pH in the reactor was controlled at 12.1, the ammonia concentration was 1 g / L, the reaction temperature was 60℃, and the stirring speed was 500 rpm. After the nucleation reaction was completed, the growth reaction continued. The growth reaction was carried out at pH 9.5, the ammonia concentration was 1 g / L, the reaction temperature was 60℃, the atmosphere composition was air / nitrogen = 19%, the stirring speed was 450 rpm, the target particle size was 4 μm, and the growth reaction time was 78 h. The slurry prepared by the reaction was first washed with 400 L of alkali and 2800 L of water, and then dried at 100℃ for 8 h. After drying, small particles of lithium-rich manganese-based cathode material precursor were obtained.

[0083] The precursor particles were analyzed by primary particle thickness, secondary particle surface pore size, secondary particle internal porosity, particle size D50, sphericity, BET, and TD tests. The results are shown in Table 1. SEM analysis of the precursor particles was also performed, and the results are attached. Figure 2 As can be seen, the precursor particles of the lithium-rich manganese-based cathode material prepared in this embodiment have a particle size of 3.94 μm and a primary particle thickness of 25–45 nm.

[0084] Example 3

[0085] The only difference from Example 1 is that the stirring speed in the nucleation reaction is 550 rpm, the atmosphere composition is air / nitrogen = 30%, and the growth reaction time is 98 h.

[0086] The precursor particles were analyzed by primary particle thickness, secondary particle surface pore size, secondary particle internal porosity, particle size D50, sphericity, BET, and TD tests. The results are shown in Table 1. SEM analysis of the precursor particles was also performed, and the results are attached. Figure 3 As can be seen, the precursor particles of the lithium-rich manganese-based cathode material prepared in this embodiment have a particle size of 3.98 μm and a primary particle thickness of 15–42 nm.

[0087] Comparative Example 1

[0088] This comparative example provides a method for preparing lithium-rich manganese-based cathode material precursor particles, the steps of which are as follows:

[0089] Prepare a 2.2 mol / L metal sulfate solution, an 8.5 mol / L alkali solution, and a 6 mol / L ammonia solution. Mix the alkali solution and ammonia solution to prepare a base solution with a pH of 12.1 and an ammonia concentration of 6 g / L in a reaction vessel.

[0090] Metal sulfate solution, alkaline solution, and ammonia were added to the base solution for reaction. The nucleation reaction time was 80 min. During the reaction, the pH in the reactor was controlled at 12.1, the ammonia concentration was 6 g / L, the reaction temperature was 60℃, and the stirring speed was 450 rpm. After the nucleation reaction was completed, the growth reaction continued. The growth reaction was carried out at pH 9.5, the ammonia concentration was 6 g / L, the reaction temperature was stabilized at 60℃, the atmosphere composition was air / nitrogen = 25%, the stirring speed was 300 rpm, the target particle size was 4 μm, and the growth reaction time was 82 h. The slurry prepared by the reaction was first washed with 400 L of alkali and 2800 L of water, and then dried at 100℃ for 8 h. After drying, small particles of lithium-rich manganese-based cathode material precursor were obtained.

[0091] The precursor particles were analyzed by primary particle thickness, secondary particle surface pore size, secondary particle internal porosity, particle size D50, sphericity, BET, and TD tests. The results are shown in Table 1. SEM analysis of the precursor particles was also performed, and the results are attached. Figure 4 It can be seen that the precursor particles of lithium-rich manganese-based cathode material prepared in this comparative example have a particle size of 3.88 μm and a primary particle thickness of 10–120 nm.

[0092] Comparative Example 2

[0093] This comparative example provides a method for preparing lithium-rich manganese-based cathode material precursor particles, the steps of which are as follows:

[0094] Prepare a 2.2 mol / L metal sulfate solution, an 8.5 mol / L alkali solution, and a 6 mol / L ammonia solution. Mix the alkali solution and ammonia solution to prepare a base solution with a pH of 12.1 and an ammonia concentration of 0.5 g / L in a reaction vessel.

[0095] Metal sulfate solution, alkaline solution, and ammonia were added to the base solution for reaction. The nucleation reaction time was 80 min. During the reaction, the pH in the reactor was controlled at 12.1, the ammonia concentration at 0.5 g / L, the reaction temperature at 60℃, and the stirring speed at 450 rpm. After the nucleation reaction was completed, the growth reaction continued. The growth reaction was carried out at pH 9.5, with an ammonia concentration of 0.5 g / L, a reaction stability of 60℃, an atmosphere composition of air / nitrogen = 13%, a stirring speed of 300 rpm, a target particle size of 4 μm, and a growth reaction time of 95 h. The slurry prepared by the reaction was first washed with 400 L of alkali and 2800 L of water, and then dried at 100℃ for 8 h. After drying, small particles of lithium-rich manganese-based cathode material precursor were obtained.

[0096] The precursor particles were analyzed by primary particle thickness, secondary particle surface pore size, secondary particle internal porosity, particle size D50, sphericity, BET, and TD tests. The results are shown in Table 1. SEM analysis of the precursor particles was also performed, and the results are attached. Figure 5 It can be seen that the precursor particles of lithium-rich manganese-based cathode material prepared in this comparative example have a particle size of 4.00 μm and a primary particle thickness of 10–120 nm.

[0097] Experimental Example 1

[0098] The performance parameters of the precursor particles prepared in the test examples and comparative examples are shown in Table 1. The precursor was used to prepare cathode materials, which were then used to fabricate lithium batteries. The energy density and rate performance of the lithium batteries were tested, and the results are shown in Table 2.

[0099] Test Method: The precursor particles prepared in the examples and comparative examples were mixed with lithium hydroxide at a molar ratio of 1:1.1 and sintered at 830°C for 8 hours to obtain lithium-rich manganese-based cathode material. Then, the cathode material, Super P (conductive carbon black), and PVDF (polyvinylidene fluoride) were mixed at a mass ratio of 8:1:1 to prepare a cathode sheet, which was then assembled with a pure lithium anode to form a CR2032 coin cell. Electrochemical performance was tested within a voltage range of 2.0–4.6V. Relevant electrochemical performance data were compared relative to those in Example 2.

[0100] Table 1. Performance parameter test results of precursor particles prepared in the examples and comparative examples.

[0101]

[0102] Table 2. Results of electrochemical performance testing of cathode materials prepared from precursor particles.

[0103]

[0104] The growth reaction speed and ammonia value in Comparative Example 1 exceeded the ranges defined by this invention, and the growth reaction speed and atmosphere in Comparative Example 2 also exceeded the ranges defined by this invention, both of which led to a decrease in cycle performance and rate performance.

[0105] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A lithium-rich manganese-based cathode material precursor particle, characterized in that, Its chemical formula is Ni a Mn b M c (OH)2, wherein 0.1≤a≤0.4, 0.5≤b≤0.9, 0≤c≤0.2, a+b+c=1, and M is selected from at least one of Co, Fe, Cr, Cu, Ti, Mg, W, Mo, Nb, Ca, Zn, Sn, Zr, Al, B, Si, and P; The lithium-rich manganese-based cathode material precursor particles are secondary particles formed by the agglomeration of primary particles. The primary particles are thin sheet-like structures with a thickness of 10 nm to 120 nm, wherein the thickness difference between the thickest and thinnest parts is ≤40 nm. The sphericity of the lithium-rich manganese-based cathode material precursor particles is 0.95 to 0.98, and the pore size on the surface of the secondary particles is 30 nm to 200 nm.

2. The lithium-rich manganese-based cathode material precursor particles according to claim 1, characterized in that, The chemical formulas satisfy: 0.2≤a≤0.35, 0.65≤b≤0.75, 0≤c≤0.1, a+b+c=1; Preferably, the primary particles are sheet-like structures with a thickness of 20 nm to 60 nm; Preferably, the sphericity of the lithium-rich manganese-based cathode material precursor particles is 0.96 to 0.97; Preferably, the pore size on the surface of the secondary particles is 40 nm to 130 nm; Preferably, the porosity inside the secondary particles is 5% to 10%, more preferably 6% to 8%.

3. The lithium-rich manganese-based cathode material precursor particles according to claim 1 or 2, characterized in that, The particle size D50 of the lithium-rich manganese-based cathode material precursor particles is 2μm to 5μm, preferably 3μm to 4μm; Preferably, the specific surface area of ​​the lithium-rich manganese-based cathode material precursor particles is 25 m². 2 / g~40m 2 / g, more preferably 29m 2 / g~36m 2 / g; Preferably, the tap density of the lithium-rich manganese-based cathode material precursor particles is 1.5 g / cm³. 3 ~1.7g / cm 3 More preferably 1.55 g / cm³ 3 ~1.65g / cm 3 .

4. A method for preparing lithium-rich manganese-based cathode material precursor particles according to any one of claims 1 to 3, characterized in that, include: The metal salt solution, precipitant solution, and complexing agent solution are introduced into the bottom liquid of the reactor to carry out the nucleation reaction first and then the growth reaction, until the particle D50 in the slurry reaches the target particle size, and then the reaction is stopped. In the nucleation reaction and the growth reaction, the reaction atmosphere includes air and nitrogen, and the volume ratio of air to nitrogen is 15% to 30%, and the reaction speed is 350 rpm to 550 rpm.

5. The preparation method according to claim 4, characterized in that, During the nucleation reaction and the growth reaction, the volume ratio of air to nitrogen in the reaction atmosphere is 18% to 25%, and the reaction speed is 450 rpm to 500 rpm. Preferably, the reaction temperature is 40℃~70℃, more preferably 50℃~65℃.

6. The preparation method according to claim 4, characterized in that, The metal salt solution is a sulfate solution with a total metal concentration of 1.5 mol / L to 2.5 mol / L; Preferably, the precipitant solution is an alkaline solution with a concentration of 8 mol / L to 12 mol / L; Preferably, the complexing agent solution is ammonia solution with a concentration of 4 mol / L to 8 mol / L; Preferably, the base solution is a mixture of liquid alkali and ammonia, and the pH value of the base solution is 11.8 to 12.3, more preferably 11.9 to 12.2; the ammonia value of the base solution is 0.5 g / L to 5 g / L, more preferably 0.5 g / L to 3 g / L. Preferably, the metal salt solution contains nickel, manganese, and a soluble salt corresponding to element M, wherein the soluble salt includes at least one of nitrate, chloride, and sulfate.

7. The preparation method according to claim 4, characterized in that, The reaction time for the nucleation reaction is 10 min to 200 min, preferably 30 min to 100 min; Preferably, the pH value of the growth reaction is 8 to 10.5, more preferably 8.5 to 10; Preferably, the ammonia value of the growth reaction is 0.5 g / L to 5 g / L, more preferably 0.5 g / L to 2 g / L; Preferably, the reaction time of the growth reaction is 50h to 120h, more preferably 60h to 100h.

8. The preparation method according to claim 7, characterized in that, Also includes: The slurry obtained after the reaction is washed and dried; Preferably, the washing process includes sequential alkaline washing and water washing; more preferably, the alkaline washing temperature is 50°C to 80°C, and the water washing temperature is 50°C to 80°C. Preferably, the drying temperature is 80℃~120℃ and the drying time is 5h~12h.

9. A lithium-rich manganese-based cathode material, characterized in that, It is prepared by combining lithium-rich manganese-based cathode material precursor particles as described in any one of claims 1 to 4 or prepared by any one of claims 5 to 8 with a lithium source.

10. A lithium battery, characterized in that, Including the lithium-rich manganese-based cathode material as described in claim 9.

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