Lithium-rich manganese-based carbonate precursor, positive electrode material and preparation method

Abstract

The present application relates to a lithium-rich manganese-based carbonate precursor, a positive electrode material and a preparation method. The preparation method for the precursor comprises the following steps: (1) mixing a metal sulfate solution, a precipitant, a complexing agent solution and a reducing agent solution, continuously adding the resulting mixture into a reaction kettle, reacting same under the protection of an inert atmosphere until a target particle size is obtained, and stopping the reaction; and (2) leaving the reaction slurry to stand, then removing the supernatant, then mixing the reaction slurry with a carbonate solution, subjecting the mixture to aging, solid-liquid separation, washing and drying, so as to obtain a lithium-rich manganese-based carbonate precursor. The preparation method can synthesize a lithium-rich manganese-based carbonate precursor having a high specific surface area, and increases the specific surface area to 40-200 m2 / g, thereby facilitating promoting the diffusion of a lithium source during a mixed lithium sintering process, and significantly improving the discharge capacity of the corresponding positive electrode material.

Description

A carbonate lithium-rich manganese-based precursor, positive electrode material and preparation method Technical Field

[0001] The present application belongs to the field of battery technology and relates to a battery material, and in particular to a carbonate lithium-rich manganese-based precursor, a positive electrode material and a preparation method. Background Art

[0002] Due to their unique crystal structure and elemental composition, lithium-rich manganese-based materials exhibit special transition metal redox and anion redox mechanisms, resulting in extremely high theoretical specific capacity and high voltage platforms. Their energy density is far higher than that of widely commercialized ternary cathode materials and lithium iron phosphate. In addition, lithium-rich manganese-based materials greatly reduce the use of expensive Co and Ni, significantly reducing material costs. Therefore, lithium-rich manganese-based materials are considered one of the most promising next-generation lithium-ion battery cathode materials and have broad market prospects.

[0003] Currently, the mainstream industrial preparation method for lithium-rich manganese-based cathode materials is co-precipitation-solid-phase sintering. This involves first obtaining a lithium-rich manganese-based precursor through co-precipitation, then mixing it with a lithium source and sintering it through solid-phase sintering to produce the cathode material. The physical and chemical properties of the precursor, including primary particle morphology, secondary particle stacking, tap density, elemental uniformity, and specific surface area, profoundly influence the physical and chemical properties of the cathode material, and thus closely influence its electrochemical performance.

[0004] The lithium-rich manganese-based precursor is mainly a transition metal hydroxide precipitate, but it has the following three problems: (1) The specific surface area of ​​the hydroxide precursor is difficult to further increase, generally 15-25m 2 / g, the low specific surface area makes the diffusion of lithium more difficult, resulting in uneven distribution of lithium and low specific capacity; (2) The lithium-rich manganese-based precursors of the hydroxide system are prone to precipitate high-valent manganese oxides on the surface of the particles, which are prone to produce impurities during the sintering process, affecting the electrochemical performance; (3) The hydroxide precursors require the use of liquid alkali during the synthesis process, resulting in high costs, which hinders the commercial application of lithium-rich manganese-based precursors and positive electrode materials.

[0005] Summary of the Invention

[0006] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0007] The purpose of the present application is to provide a carbonate lithium-rich manganese-based precursor, a positive electrode material and a preparation method. The preparation method can obtain a carbonate lithium-rich manganese-based precursor with a higher specific surface area, which facilitates the diffusion of lithium sources when preparing positive electrode materials and significantly improves the discharge capacity; moreover, it can also reduce the preparation cost of the precursor material.

[0008] To achieve the purpose of this application, this application adopts the following technical solutions:

[0009] In a first aspect, an embodiment of the present application provides a method for preparing a carbonate lithium-rich manganese-based precursor, the preparation method comprising the following steps:

[0010] (1) a mixed metal sulfate solution, a precipitant, a complexing agent solution, and a reducing agent solution are added to a reactor in parallel and continuously added thereto, and the reaction is stopped after the target particle size is reached under an inert atmosphere;

[0011] (2) after the reaction slurry is allowed to stand, the supernatant is removed, and then the slurry is mixed with a carbonate solution, and the mixture is aged, solid-liquid separated, washed and dried to obtain the carbonate lithium-rich manganese-based precursor;

[0012] The precipitant in step (1) includes carbonate and / or CO2 gas.

[0013] The preparation method provided in the first aspect of the embodiment of the present application uses carbonate solution and / or CO2 gas as a precipitant, which can realize the preparation of carbonate lithium-rich manganese-based precursor, and the specific surface area of ​​the prepared precursor material can reach 40-200m 2 / g, and when used to prepare positive electrode materials, it can significantly promote the diffusion of lithium sources and improve the discharge capacity; moreover, the obtained carbonate lithium-rich manganese-based precursor is not easy to precipitate manganese oxide crystals, and the preparation cost can be reduced by 5-10% compared with traditional hydroxide precursors.

[0014] When the precipitant in step (1) of the embodiment of the present application is a carbonate, the carbonate includes a carbonate solution or a carbonate solid, and the present application does not make any specific limitation, as long as the pH value of the reaction system can be stabilized within the range required by the process.

[0015] In one embodiment, during the aging in step (2), the concentration of carbonate is 0.4-2 mol / L, for example, 0.4 mol / L, 0.8 mol / L, 1.2 mol / L, 1.6 mol / L or 2 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0016] In one embodiment, the aging temperature in step (2) is 40-100°C, for example, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C or 100°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0017] In one embodiment, the aging time in step (2) is 6-10 hours, for example, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] In one embodiment, the carbonate in the carbonate solution in step (2) includes sodium carbonate.

[0019] In the embodiment of the present application, by using the carbonate, an exchange reaction occurs between the carbonate radical and the sulfate radical in the interlayer, thereby reducing the impurity sulfur content.

[0020] In one embodiment, the carbonate in the precipitating agent in step (1) includes sodium carbonate and / or ammonium bicarbonate.

[0021] In one embodiment, the complexing agent in the complexing agent solution in step (1) includes any one or a combination of at least two of ammonia, ethylenediaminetetraacetic acid or sodium pyrophosphate. Typical but non-limiting combinations include the combination of ethylenediaminetetraacetic acid and ammonia water, or the combination of ammonia and sodium pyrophosphate.

[0022] In one embodiment, the concentration of the complexing agent solution in step (1) is 0.1 - 0.3 mol / L. For example, it can be 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L or 0.3 mol / L, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0023] In one embodiment, the reducing agent in the reducing agent solution in step (1) includes any one or a combination of at least two of sodium sulfite, sodium thiosulfate, sodium citrate or hydrogen sulfide. Typical but non-limiting combinations include the combination of sodium sulfite and sodium thiosulfate, the combination of sodium thiosulfate and sodium citrate, the combination of sodium sulfite, sodium thiosulfate and hydrogen sulfide, or the combination of sodium sulfite, sodium thiosulfate, sodium citrate and hydrogen sulfide.

[0024] In one embodiment, the concentration of the reducing agent solution in step (1) is 0.05 - 0.1 mol / L. For example, it can be 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L or 0.1 mol / L, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0025] In one embodiment, the metal ions in the mixed salt solution in step (1) include nickel, cobalt and manganese, and the molar ratio of nickel, cobalt and manganese is x:y:z, where 0 < x ≤ 0.6, 0 < y ≤ 0.5, 0.2 ≤ z < 1, and x + y + z = 1.

[0026] The value range of x is 0 < x ≤ 0.6. For example, it can be 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5 or 0.6, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0027] The value range of y is 0≤y≤0.5, for example, it can be 0, 0.01, 0.05, 0.1, 0.2, 0.3, 0.4 or 0.5, but is not limited to the listed values. Other values ​​not listed in the numerical range are also applicable.

[0028] The value range of z is 0.2≤z<1, for example, it can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 0.9, 0.95 or 0.99, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0029] In one embodiment, the total concentration of nickel, cobalt and manganese in the mixed metal sulfate solution of step (1) is 1-2.5 mol / L, for example, 1 mol / L, 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.4 mol / L or 2.5 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] In one embodiment, the reaction temperature of step (1) is 20-90°C, for example, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or 90°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] In one embodiment, during the reaction in step (1), the pH of the system is 7.5-10, for example, 7.5, 8, 9 or 10, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] In one embodiment, during the reaction in step (1), the reducing agent concentration in the system is 1×10 -3 -1×10 -2 mol / L. For example, it can be 1×10 -3 mol / L, 2×10 -3 mol / L、4×10 -3 mol / L、6×10 -3 mol / L、8×10 -3 mol / L or 1×10 -2 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] In one embodiment, during the reaction in step (1), the concentration of the complexing agent in the system is 5×10 -3 -5×10 -2 mol / L. For example, it can be 5×10 -3 mol / L、7×10-3 mol / L、9×10 -3 mol / L, 1×10 -2 mol / L、3×10 -2 mol / L or 5×10 -2 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0034] In one embodiment, the reaction in step (1) is carried out under stirring conditions, and the stirring speed is 200-400 rpm, for example, it can be 200 rpm, 250 rpm, 300 rpm, 350 rpm or 400 rpm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0035] In one embodiment, during the washing, the temperature of the washing medium is 40-100°C, for example, 40°C, 50°C, 60°C, 70°C, 80°C or 100°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] In one embodiment, the drying temperature is 40-250°C, for example, it can be 40°C, 50°C, 60°C, 80°C, 100°C, 120°C, 150°C, 180°C, 200°C or 250°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] In a second aspect, an embodiment of the present application provides a carbonate lithium-rich manganese-based precursor, which is prepared by the preparation method described in the first aspect.

[0038] In the carbonate lithium-rich manganese-based precursor obtained in the embodiment of the present application, the molar ratio of nickel, cobalt and manganese is the same as the molar ratio of nickel, cobalt and manganese in the mixed salt solution.

[0039] The particle size D50 of the carbonate lithium-rich manganese-based precursor obtained in the embodiment of the present application is 1-25 μm, for example, it can be 1 μm, 5 μm, 10 μm, 15 μm, 20 μm or 25 μm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0040] In a third aspect, an embodiment of the present application provides a positive electrode material, which is prepared from the carbonate lithium-rich manganese-based precursor described in the second aspect.

[0041] In a fourth aspect, an embodiment of the present application provides a method for preparing the positive electrode material as described in the third aspect, the preparation method comprising:

[0042] The positive electrode material is obtained by uniformly mixing a carbonate lithium-rich manganese-based precursor and a lithium source, and solid-phase high-temperature sintering.

[0043] The lithium source includes lithium carbonate and / or lithium hydroxide.

[0044] The amount of lithium source used in the embodiments of the present application is the amount of lithium source required to fully react the carbonate lithium-rich manganese-based precursor, and this application does not make any specific restrictions here.

[0045] The temperature of the solid-phase high-temperature sintering described in the fourth aspect of the embodiment of the present application is 600-900°C, for example, it can be 600°C, 700°C, 800°C or 900°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] The time for solid-phase high-temperature sintering described in the fourth aspect of the embodiment of the present application is 5-20 hours, for example, it can be 5 hours, 10 hours, 15 hours or 20 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] The preparation method described in the fourth aspect further includes conventional cooling, crushing and screening in the art after sintering, and this application does not make too many restrictions on this.

[0048] Compared with the prior art, this application has the following beneficial effects:

[0049] The preparation method of the present application uses carbonate solution and / or CO2 gas as a precipitant, which can realize the preparation of carbonate lithium-rich manganese-based precursors, and the specific surface area of ​​the prepared precursor material can reach 40-200m 2 / g, and when used to prepare positive electrode materials, it can significantly promote the diffusion of lithium sources and improve the discharge capacity; moreover, the obtained carbonate lithium-rich manganese-based precursor is not easy to precipitate manganese oxide crystals, and the preparation cost can be reduced by 5-10% compared with traditional hydroxide precursors.

[0050] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0052] FIG1 is a SEM image of the carbonate lithium-rich manganese-based precursor obtained in Example 1. DETAILED DESCRIPTION

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

[0054] Example 1

[0055] This embodiment provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0056] (1) Under nitrogen atmosphere, a mixed metal sulfate solution, sodium carbonate, ammonia solution, and sodium thiosulfate solution were continuously injected into the reactor in parallel, with the pH maintained at 8.4, and reacted at 60°C until the particle size D50 reached 8 μm, and then the reaction was stopped;

[0057] The concentration of the ammonia solution is 0.2 mol / L, and the concentration of the sodium thiosulfate solution is 0.08 mol / L; the reaction is accompanied by stirring at a stirring speed of 300 rpm;

[0058] The mixed metal sulfate solution is a mixed solution of nickel sulfate, cobalt sulfate and manganese sulfate, the total concentration of nickel, cobalt and manganese is 2.5 mol / L, and the molar ratio of nickel, cobalt and manganese is 0.16:0.16:0.68;

[0059] During the reaction, the concentration of sodium thiosulfate in the system was maintained at 0.005 mol / L, and the concentration of the complexing agent was maintained at 0.02 mol / L;

[0060] (2) After the reaction slurry is allowed to stand, the supernatant is removed, and then the slurry is mixed with a sodium carbonate solution to make the concentration of sodium carbonate in the aging system 2 mol / L, and then aged at 70° C. for 8 h, solid-liquid separation, washing and drying to obtain the carbonate lithium-rich manganese-based precursor;

[0061] The washing process is carried out by sequentially using a sodium carbonate solution and water; during washing, the temperature of the washing medium is 80°C; and the drying temperature is 150°C.

[0062] (3) uniformly mixing the carbonate lithium-rich manganese-based precursor and lithium carbonate, and sintering at 800° C. for 12 hours to obtain the positive electrode material.

[0063] The SEM image of the carbonate lithium-rich manganese-based precursor obtained in this example is shown in FIG1 .

[0064] Example 2

[0065] This embodiment provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0066] (1) Under nitrogen atmosphere, a mixed metal sulfate solution, sodium carbonate, ammonia solution, and sodium thiosulfate solution were continuously injected into the reactor in parallel, with the pH maintained at 7.5, and reacted at 60°C until the particle size D50 reached 2 μm, and then the reaction was stopped;

[0067] The concentration of the ammonia solution is 0.1 mol / L, and the concentration of the sodium thiosulfate solution is 0.05 mol / L; the reaction is accompanied by stirring at a stirring speed of 200 rpm;

[0068] The mixed metal sulfate solution is a mixed solution of nickel sulfate, cobalt sulfate and manganese sulfate, the total concentration of nickel, cobalt and manganese is 1 mol / L, and the molar ratio of nickel, cobalt and manganese is 0.16:0.16:0.68;

[0069] During the reaction, the concentration of sodium thiosulfate in the system was maintained at 0.01 mol / L, and the concentration of the complexing agent was maintained at 0.005 mol / L;

[0070] (2) After the reaction slurry is allowed to stand, the supernatant is removed, and then the slurry is mixed with a sodium carbonate solution to adjust the concentration of sodium carbonate in the aging system to 0.4 mol / L, and then aged at 40° C. for 10 h, solid-liquid separation, washing, and drying to obtain the carbonate lithium-rich manganese-based precursor;

[0071] Washing is carried out by sequentially using sodium carbonate solution and water; during washing, the temperature of the washing medium is 40°C; the drying temperature is 80°C;

[0072] (3) uniformly mixing the carbonate lithium-rich manganese-based precursor and lithium carbonate, and sintering at 600° C. for 20 hours to obtain the positive electrode material.

[0073] Example 3

[0074] This embodiment provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0075] (1) Under nitrogen atmosphere, a mixed sulfate solution, sodium carbonate, ammonia solution, and sodium thiosulfate solution were continuously injected into the reactor in parallel, with the pH maintained at 10, and reacted at 60°C until the particle size D50 reached 20 μm, and then the reaction was stopped;

[0076] The concentration of the ammonia solution is 0.3 mol / L, and the concentration of the sodium thiosulfate solution is 0.1 mol / L; the reaction is accompanied by stirring at a stirring speed of 400 rpm;

[0077] The mixed metal sulfate solution is a mixed solution of nickel sulfate, cobalt sulfate and manganese sulfate, the total concentration of nickel, cobalt and manganese is 1.5 mol / L, and the molar ratio of nickel, cobalt and manganese is 0.16:0.16:0.68;

[0078] During the reaction, the concentration of sodium thiosulfate in the system was maintained at 0.001 mol / L, and the concentration of the complexing agent was maintained at 0.05 mol / L;

[0079] (2) After the reaction slurry is allowed to stand, the supernatant is removed, and then the slurry is mixed with a sodium carbonate solution to adjust the concentration of sodium carbonate in the aging system to 1.5 mol / L, and then aged at 60° C. for 10 h, solid-liquid separation, washing, and drying to obtain the carbonate lithium-rich manganese-based precursor;

[0080] The washing process is carried out by sequentially using a sodium carbonate solution and water; during washing, the temperature of the washing medium is 100°C; and the drying temperature is 250°C;

[0081] (3) uniformly mixing the carbonate lithium-rich manganese-based precursor and lithium carbonate, and sintering at 900° C. for 5 h to obtain the positive electrode material.

[0082] Example 4

[0083] This embodiment provides a method for preparing a positive electrode material, which is the same as that of Example 1 except that an equimolar amount of the reducing agent in the reducing agent solution is replaced by sodium sulfite.

[0084] Example 5

[0085] This embodiment provides a method for preparing a positive electrode material, which is the same as that of Example 1 except that an equimolar amount of the reducing agent in the reducing agent solution is replaced by sodium citrate.

[0086] Example 6

[0087] This embodiment provides a method for preparing a positive electrode material, which is the same as that of Example 1 except that the precipitant is CO2 gas.

[0088] Example 7

[0089] This embodiment provides a method for preparing a positive electrode material. Except that the mixed salt solution is a mixed solution of nickel sulfate, cobalt sulfate and manganese sulfate, the total concentration of nickel, cobalt and manganese is 2.5 mol / L, and the molar ratio of nickel, cobalt and manganese is 0.40:0:0.60, the rest is the same as Example 1.

[0090] Example 8

[0091] This embodiment provides a method for preparing a positive electrode material. Except that the mixed salt solution is a mixed solution of nickel sulfate, cobalt sulfate and manganese sulfate, the total concentration of nickel, cobalt and manganese is 2.5 mol / L, and the molar ratio of nickel, cobalt and manganese is 0.35:0.05:0.60, the rest is the same as Example 1.

[0092] Comparative Example 1

[0093] This comparative example provides a method for preparing a positive electrode material, which is the same as Example 1 except that the precipitant is liquid alkali.

[0094] Performance Characterization

[0095] The specific surface areas of the precursors obtained in the above examples and comparative examples were measured using the following method: 100 mg of the precursor sample to be tested was placed in a sample tube; after sealing, the sample was heated and vacuum degassed to remove gases adsorbed on the surface of the material; liquid nitrogen was added, and adsorption and desorption tests were performed according to the test parameters. The results are shown in Table 1.

[0096] The positive electrode materials obtained in the above examples and comparative examples are prepared into lithium-ion batteries by the following method:

[0097] The positive electrode material, binder polyvinylidene fluoride, and conductive agent Super P were added to N-methylpyrrolidone at a mass ratio of 97:1.5:1.5 and stirred to form a first positive electrode slurry; the first positive electrode slurry was then evenly coated on the positive electrode current collector aluminum foil, dried and roll-pressed to obtain a positive electrode sheet;

[0098] Graphite, conductive agent acetylene black, thickener CMC and binder SBR are mixed in a mass ratio of 96:1:1.5:1.5, and deionized water is added as a solvent and stirred thoroughly to obtain a negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode current collector copper foil, and the negative electrode sheet is obtained after drying, cold pressing and slitting;

[0099] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1, and then fully dried lithium salt LiPF6 was dissolved in the mixed solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0100] The positive electrode sheet, separator, and negative electrode sheet are stacked in sequence, then wrapped with aluminum-plastic film. After drying, the electrolyte is injected. After packaging, standing and formation processes, a lithium-ion battery is obtained. The separator is a PE porous film with a thickness of 11μm, an air permeability of 280s / 100mL, and a porosity of 40%.

[0101] The specific capacity and cycle capacity retention rate of the obtained lithium-ion battery were tested, and the results are shown in Table 1.

[0102] The specific capacity test method is as follows: using the Blue Electric Battery Test System, at 25°C, the lithium-ion battery is charged and discharged three times in the voltage range of 2.5V to 4.8V at a charge and discharge rate of 0.04A / g (calculated based on the mass of the positive electrode material) to measure the battery specific capacity;

[0103] The test method for the cycle capacity retention rate is: at 25°C, cycle at a charge and discharge rate of 0.19A / g (calculated based on the mass of the positive electrode material). After 100 cycles, the discharge capacity of the battery at this time is divided by the discharge capacity of the first cycle, which is the battery's 100-cycle cycle capacity retention rate.

[0104] Table 1

[0105] In summary, the preparation method of the present application uses carbonate solution and / or CO2 gas as a precipitant, which can realize the preparation of carbonate lithium-rich manganese-based precursors, and the specific surface area of ​​the prepared precursor material can reach 40-200m 2 / g, and when used to prepare positive electrode materials, it can significantly promote the diffusion of lithium sources and improve the discharge capacity; moreover, the obtained carbonate lithium-rich manganese-based precursor is not easy to precipitate manganese oxide crystals, and the preparation cost can be reduced by 5-10% compared with traditional hydroxide precursors.

[0106] The above description is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Those skilled in the art should understand that any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application fall within the protection scope and disclosure scope of the present application.

Claims

1. A preparation method of a lithium-rich manganese-based carbonate precursor, the preparation method comprising the following steps: (1) Continuously adding a mixed metal sulfate solution, a precipitant, a complexing agent solution, and a reducing agent solution in parallel into a reaction kettle, reacting under an inert atmosphere protection until the target particle size is reached, and then stopping the reaction; (2) After the reaction slurry is left standing, the supernatant is removed, and then it is mixed with a carbonate solution, aged, subjected to solid-liquid separation, washed, and dried to obtain the lithium-rich manganese-based carbonate precursor; The precipitant in step (1) includes carbonate and / or CO2 gas.

2. The preparation method according to claim 1, wherein When aging in step (2), the concentration of the carbonate is 0.4 - 2 mol / L; Optionally, the aging temperature in step (2) is 40 - 100 °C; Optionally, the carbonate in the carbonate solution in step (2) includes sodium carbonate.

3. The preparation method according to claim 1 or 2, wherein The carbonate in the precipitant in step (1) includes sodium carbonate and / or ammonium bicarbonate.

4. The preparation method according to any one of claims 1 to 3, wherein: The complexing agent in the complexing agent solution in step (1) includes any one or a combination of at least two of ammonia, ethylenediaminetetraacetic acid, or sodium pyrophosphate; Optionally, the concentration of the complexing agent solution in step (1) is 0.1 - 0.3 mol / L; Optionally, the reducing agent in the reducing agent solution in step (1) includes any one or a combination of at least two of sodium sulfite, sodium thiosulfate, sodium citrate, or hydrogen sulfide; Optionally, the concentration of the reducing agent solution in step (1) is 0.05 - 0.1 mol / L.

5. The preparation method according to any one of claims 1 to 4, wherein: The metal ions in the mixed metal sulfate solution in step (1) include nickel, cobalt, and manganese, and the molar ratio of nickel, cobalt, and manganese is x:y:z, where 0 < x ≤ 0.6, 0 ≤ y ≤ 0.5, 0.2 ≤ z < 1, and x + y + z = 1; Optionally, in the mixed metal sulfate solution in step (1), the total concentration of nickel, cobalt, and manganese is 1 - 2.5 mol / L.

6. The preparation method according to any one of claims 1 to 5, wherein: The reaction temperature in step (1) is 20 - 90 °C; Optionally, when reacting in step (1), the pH of the system is 7.5 - 10; Optionally, during the reaction in step (1), the reducing agent concentration in the system is 1×10 -3 -1×10 -2 mol / L; Optionally, the reaction in step (1) is carried out under stirring conditions, and the stirring speed is 200 - 400 rpm.

7. The preparation method according to any one of claims 1 to 6, wherein: The washing is carried out by washing successively with a carbonate solution and water; Optionally, when washing, the temperature of the washing medium is 40 - 100 °C; Optionally, the drying temperature is 40 - 250 °C.

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

9. A cathode material, the cathode material being prepared by the lithium-rich manganese-based carbonate precursor according to claim 8.

10. A preparation method of a cathode material as claimed in claim 9, the preparation method comprising: Uniformly mixing the lithium-rich manganese-based carbonate precursor and a lithium source, and performing high-temperature solid-phase sintering to obtain the cathode material.

Images