Modified lithium-rich manganese-based precursor, and preparation method therefor and use thereof

Abstract

A modified lithium-rich manganese-based precursor, and a preparation method therefor and the use thereof. The preparation method comprises: (1) mixing a modifying agent, a complexing agent, an alkali liquor and water to obtain a reaction base solution; and (2) adding a nickel-cobalt-manganese mixed salt solution, a complexing agent and an alkali liquor to the reaction base solution obtained in step (1), subjecting same to a co-precipitation reaction, followed by solid-liquid separation to obtain a modified lithium-rich manganese-based precursor, wherein the modifying agent in step (1) includes any one or a combination of at least two of sodium dodecyl sulfate, hexadecyl trimethyl ammonium bromide or hexadecyl trimethyl ammonium chloride. According to the preparation method, a specific type of modifying agent is added to the reaction base solution, thereby effectively avoiding the current defects of particle aggregation and poor dispersity of the lithium-rich manganese-based precursor in the reaction stage, improving the structural stability and cycle performance of the resulting lithium-rich manganese-based material, simplifying the technological process, reducing the production difficulty and operating costs, and facilitating industrial production and application.

Description

A modified lithium-rich manganese-based precursor and its preparation method and application Technical Field

[0001] The present application belongs to the technical field of lithium-ion batteries and relates to a lithium-rich manganese-based precursor, and in particular to a modified lithium-rich manganese-based precursor and a preparation method and application thereof. Background Art

[0002] In recent years, lithium-rich manganese-based cathode materials composed of LiMO2 (M = Ni, Co, Mn) have become one of the most promising cathode materials for lithium-ion batteries due to their discharge capacity, which is nearly twice that of traditional cathode materials (such as lithium cobalt oxide, lithium iron phosphate, and lithium manganese oxide). Currently, research on lithium-rich manganese-based cathode materials is increasing, but research on their precursor materials is very limited. The quality of the precursor materials is extremely important for the performance of lithium-rich manganese-based materials.

[0003] CN110323430A discloses a preparation method of a lithium-rich manganese-based material and a lithium-rich manganese-based material. The preparation method comprises: 2+ and M 2+ A mixed metal salt solution, a complexing agent, a precipitant and a reducing agent are mixed to prepare a lithium-rich manganese precursor. By controlling the concentration of the reducing agent, a lithium-rich manganese-based material with better electrochemical performance is prepared. However, during the co-precipitation process of the lithium-rich manganese-based precursor, as the manganese content increases, the particles grow more densely and agglomerate severely. The overall morphology of the precursor is difficult to control, and the sphericity and dispersibility are poor, resulting in an unstable structure of the positive electrode material sintered subsequently and poor cycle performance.

[0004] CN110323430A discloses a lithium-rich manganese-based layered lithium-ion battery cathode material synthesized with the assistance of distiller's grains and a preparation method thereof. The loose porous structure of distiller's grains is utilized to prepare a lithium-rich manganese-based layered lithium-ion battery cathode material with good dispersion. However, the above preparation process requires ultrasonic infiltration, negative pressure impregnation, drying, etc., which is a complex process. Moreover, compared with the control of the precursor morphology, the modification effect of the positive electrode sintering is not ideal.

[0005] CN110040790A discloses a highly spherical nickel-cobalt-manganese ternary precursor and its preparation method. A nickel-cobalt-manganese mixed salt solution, a complexing agent solution, and a suspension of hard microspheres are added to a reaction base solution at a uniform, parallel flow rate. The addition of the hard microspheres increases the frequency and number of particle collisions during the coprecipitation process under vigorous stirring, resulting in highly dispersible and spherical precursor particles. This preparation method is complex and requires subsequent separation of the hard microsphere suspension from the slurry, requiring additional separation equipment. This increases production complexity and operating costs, making it unsuitable for subsequent large-scale production.

[0006] It can be seen that how to provide a lithium-rich manganese-based precursor and its preparation method, improve the structural stability and cycle performance of the obtained lithium-rich manganese-based material, simplify the process flow, and reduce production difficulty and operating costs have become problems that technical personnel in this field urgently need to solve.

[0007] Summary of the Invention

[0008] 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.

[0009] The purpose of this application is to provide a modified lithium-rich manganese-based precursor and its preparation method and application. The preparation method effectively avoids the defects of particle agglomeration and poor dispersion of the current lithium-rich manganese-based precursor in the reaction stage by adding a specific type of modifier to the reaction base liquid, improves the structural stability and cycle performance of the obtained lithium-rich manganese-based material, simplifies the process flow, reduces production difficulty and operating costs, and is conducive to industrial production and application.

[0010] To achieve this goal, this application adopts the following technical solutions:

[0011] In a first aspect, the present application provides a method for preparing a modified lithium-rich manganese-based precursor, the preparation method comprising the following steps:

[0012] (1) mixing a modifier, a complexing agent, an alkali solution and water to obtain a reaction base solution;

[0013] (2) Adding a nickel-cobalt-manganese mixed salt solution, a complexing agent and an alkaline solution to the reaction base liquid obtained in step (1) to carry out a coprecipitation reaction, and obtaining a modified lithium-rich manganese-based precursor after solid-liquid separation.

[0014] Wherein, the modifier in step (1) includes any one of sodium lauryl sulfate, cetyltrimethylammonium bromide or cetyltrimethylammonium chloride, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of sodium lauryl sulfate and cetyltrimethylammonium bromide, a combination of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride, a combination of sodium lauryl sulfate and cetyltrimethylammonium chloride, or a combination of sodium lauryl sulfate, cetyltrimethylammonium bromide and cetyltrimethylammonium chloride.

[0015] The present application effectively avoids the problems of tight growth, easy agglomeration, and poor morphology of the current lithium-rich manganese precursor during the reaction stage by adding a specific type of modifier to the reaction base liquid, thereby producing a modified lithium-rich manganese-based precursor with high dispersion and uniform particle distribution, thereby improving the structural stability and cycle performance of the subsequently obtained lithium-rich manganese-based material.

[0016] In addition, the preparation method provided in this application only requires adding a modifier to the reaction base liquid, without the need for additional feed pipelines, which simplifies the process flow, reduces production difficulty and operating costs, and is conducive to industrial production applications.

[0017] In one embodiment, the mixing mass ratio of the modifier to water in step (1) is 1:(30-50), for example, it can be 1:30, 1:32, 1:34, 1:36, 1:38, 1:40, 1:42, 1:44, 1:46, 1:48 or 1:50, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] In one embodiment, the complexing agent in step (1) and step (2) independently comprises oxalic acid solution and / or ammonia water, and can further be oxalic acid solution.

[0019] In one embodiment, the mass concentration of the oxalic acid solution is 5-15 g / L, for example, it can be 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L or 15 g / L, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0020] In one embodiment, the alkali solution in step (1) and step (2) independently comprises sodium hydroxide solution and / or potassium hydroxide solution.

[0021] In one embodiment, the mass fraction of the alkali solution in step (1) and step (2) is 30-35wt%, for example, it can be 30wt%, 30.5wt%, 31wt%, 31.5wt%, 32wt%, 32.5wt%, 33wt%, 33.5wt%, 34wt%, 34.5wt% or 35wt%, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0022] In one embodiment, the pH value of the reaction base solution in step (1) is 11.5-12, for example, it can be 11.5, 11.6, 11.7, 11.8, 11.9 or 12, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0023] In one embodiment, the anions in the nickel-cobalt-manganese mixed salt solution in step (2) include any one of sulfate, nitrate or chloride ions, or a combination of at least two of them. Typical but non-limiting combinations include a combination of sulfate and nitrate, a combination of nitrate and chloride, a combination of sulfate and chloride, or a combination of sulfate, nitrate and chloride.

[0024] In one embodiment, the elemental molar ratio of nickel, cobalt and manganese in the nickel-cobalt-manganese mixed salt solution of step (2) is set to x:y:z, then x+y+z=1, and z≥0.6, for example, z can be 0.6, 0.65, 0.7, 0.75, 0.8, 0.85 or 0.9, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0025] In one embodiment, the mass concentration of the ternary salt in the nickel-cobalt-manganese mixed salt solution in step (2) is 90-110 g / L, for example, it can be 90 g / L, 92 g / L, 94 g / L, 96 g / L, 98 g / L, 100 g / L, 102 g / L, 104 g / L, 106 g / L, 108 g / L or 110 g / L, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0026] In one embodiment, the coprecipitation reaction in step (2) is carried out in a nitrogen atmosphere.

[0027] In one embodiment, the temperature of the coprecipitation reaction in step (2) is 50-60°C, for example, it can be 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0028] In one embodiment, the pH value of the coprecipitation reaction in step (2) is 10-12, for example, it can be 10, 10.2, 10.4, 10.6, 10.8, 11, 11.2, 11.4, 11.6, 11.8 or 12, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0029] In one embodiment, the coprecipitation reaction in step (2) is accompanied by stirring, and the stirring rate is 400-800 rpm, for example, it can be 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm or 800 rpm, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0030] In one embodiment, the solid-liquid separation in step (2) comprises any one of centrifugation, filtration or suction filtration, and can further be suction filtration.

[0031] In one embodiment, step (2) further includes washing and drying after the solid-liquid separation.

[0032] In one embodiment, the washing method includes: washing with alkaline solution and deionized water successively for 2-5 times, for example, 2 times, 3 times, 4 times or 5 times.

[0033] In one embodiment, the drying temperature is 100-150°C, for example, it can be 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C or 150°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] As an optional technical solution of this application, the preparation method includes the following steps:

[0035] (1) mixing a modifier, a complexing agent, an alkali solution, and water to obtain a reaction base solution having a pH value of 11.5-12; the modifier comprises any one of sodium lauryl sulfate, hexadecyltrimethylammonium bromide, or hexadecyltrimethylammonium chloride, or a combination of at least two thereof, and the mixing mass ratio of the modifier to water is 1:(30-50);

[0036] (2) adding a nickel-cobalt-manganese mixed salt solution, a chelating agent and an alkali solution to the reaction base liquid obtained in step (1), carrying out a coprecipitation reaction in a nitrogen atmosphere, and obtaining a modified lithium-rich manganese-based precursor after filtration, washing and drying; the anions in the nickel-cobalt-manganese mixed salt solution include any one of sulfate, nitrate or chloride ions or a combination of at least two thereof, and setting the elemental molar ratio of nickel, cobalt and manganese in the nickel-cobalt-manganese mixed salt solution to x:y:z, then x+y+z=1, and z≥0.6; the mass concentration of the ternary salt in the nickel-cobalt-manganese mixed salt solution is 90-110 g / L; the temperature of the coprecipitation reaction is 50-60°C, and the pH value is 10-12; the coprecipitation reaction is accompanied by stirring, and the stirring rate is 400-800 rpm; the washing method includes: washing with alkali solution and deionized water 2-5 times in sequence; and the drying temperature is 100-150°C.

[0037] Wherein, the complexing agents in step (1) and step (2) independently include oxalic acid solution with a mass concentration of 5-15 g / L, and the alkali solution independently includes sodium hydroxide solution and / or potassium hydroxide solution, and the mass fraction of the alkali solution is 30-35 wt%.

[0038] In a second aspect, the present application provides a modified lithium-rich manganese-based precursor, which is prepared by the preparation method described in the first aspect.

[0039] In a third aspect, the present application provides a lithium-rich manganese-based positive electrode material, which is prepared by mixing and sintering the modified lithium-rich manganese-based precursor described in the second aspect with a lithium source.

[0040] In a fourth aspect, the present application provides a lithium-ion battery, wherein the positive electrode material of the lithium-ion battery adopts the lithium-rich manganese-based positive electrode material as described in the third aspect.

[0041] Compared with the prior art, this application has the following beneficial effects:

[0042] (1) The present invention effectively avoids the problems of dense growth, easy agglomeration, and poor morphology of the current lithium-rich manganese precursor during the reaction stage by adding a specific type of modifier to the reaction base liquid, thereby obtaining a modified lithium-rich manganese-based precursor with high dispersibility and uniform particle distribution, thereby improving the structural stability and cycle performance of the subsequently obtained lithium-rich manganese-based material;

[0043] (2) The preparation method provided in this application only requires adding a modifier to the reaction base liquid, without the need for additional feed pipelines, which simplifies the process flow, reduces production difficulty and operating costs, and is conducive to industrial production applications.

[0044] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] 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.

[0046] FIG1 is a SEM photograph of the modified lithium-rich manganese-based precursor obtained in Example 1;

[0047] FIG2 is a SEM photograph of the lithium-rich manganese-based precursor obtained in Comparative Example 1. DETAILED DESCRIPTION

[0048] 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.

[0049] Example 1

[0050] This embodiment provides a modified lithium-rich manganese-based precursor and a preparation method thereof, the preparation method comprising the following steps:

[0051] (1) preparing a nickel-cobalt-manganese ternary sulfate solution with a mass concentration of 100 g / L according to the element molar ratio of Ni:Co:Mn=0.167:0.167:0.666, and preparing a sodium hydroxide solution with a mass fraction of 32 wt% and an oxalic acid solution with a mass concentration of 10 g / L;

[0052] (2) 300 g of sodium lauryl sulfate, 50 g of oxalic acid solution, 80 g of sodium hydroxide solution, and 13.4 L of pure water were added to a reaction kettle in sequence to obtain a reaction bottom solution with a pH value of 11.8;

[0053] (3) using a peristaltic pump to simultaneously introduce nickel-cobalt-manganese ternary sulfate solution (4 mL / min), oxalic acid solution (0.8 mL / min) and sodium hydroxide solution (1.28 mL / min) into the reaction base solution obtained in step (1), setting the stirring rate of the reactor to 600 rpm, the reaction temperature to 58° C., the pH value to between 10.4 and 10.6, and carrying out a coprecipitation reaction in a nitrogen atmosphere;

[0054] (4) The slurry obtained after the reaction is transferred to a suction filtration bottle for filtration, and washed three times with sodium hydroxide solution and deionized water. The obtained solid material is transferred to an oven and fully dried at 120°C to obtain a highly dispersed modified lithium-rich manganese-based precursor.

[0055] Example 2

[0056] This embodiment provides a modified lithium-rich manganese-based precursor and a preparation method thereof, the preparation method comprising the following steps:

[0057] (1) preparing a nickel-cobalt-manganese ternary nitrate solution with a mass concentration of 90 g / L according to the element molar ratio of Ni:Co:Mn=0.30:0.05:0.65, and preparing a potassium hydroxide solution with a mass fraction of 30 wt% and an oxalic acid solution with a mass concentration of 5 g / L;

[0058] (2) 300 g of sodium lauryl sulfate, 50 g of oxalic acid solution, 80 g of potassium hydroxide solution, and 9 L of pure water were added to a reaction kettle in sequence to obtain a reaction bottom solution with a pH value of 12;

[0059] (3) using a peristaltic pump to simultaneously introduce nickel-cobalt-manganese ternary nitrate solution (4 mL / min), oxalic acid solution (0.8 mL / min) and potassium hydroxide solution (1.28 mL / min) into the reaction base solution obtained in step (1), setting the stirring rate of the reactor to 400 rpm, the reaction temperature to 50° C., the pH value to between 10.0 and 11.0, and conducting a coprecipitation reaction in a nitrogen atmosphere;

[0060] (4) The slurry obtained after the reaction is transferred to a suction filtration bottle for filtration, washed twice with potassium hydroxide solution and deionized water, and the obtained solid material is transferred to an oven and fully dried at 150° C. to obtain a highly dispersed modified lithium-rich manganese-based precursor.

[0061] Example 3

[0062] This embodiment provides a modified lithium-rich manganese-based precursor and a preparation method thereof, the preparation method comprising the following steps:

[0063] (1) preparing a nickel-cobalt-manganese ternary chloride solution with a mass concentration of 110 g / L according to the element molar ratio of Ni:Co:Mn=0.30:0.10:0.60, and preparing a sodium hydroxide solution with a mass fraction of 35 wt% and an oxalic acid solution with a mass concentration of 15 g / L;

[0064] (2) 300 g of sodium lauryl sulfate, 50 g of oxalic acid solution, 80 g of sodium hydroxide solution, and 15 L of pure water were added to a reaction kettle in sequence to obtain a reaction bottom solution with a pH value of 11.5;

[0065] (3) using a peristaltic pump to simultaneously introduce a nickel-cobalt-manganese ternary chloride solution (4 mL / min), an oxalic acid solution (0.8 mL / min), and a sodium hydroxide solution (1.28 mL / min) into the reaction base solution obtained in step (1), setting the stirring rate of the reactor to 800 rpm, the reaction temperature to 60° C., and the pH value to between 11.0 and 12.0, and conducting a coprecipitation reaction in a nitrogen atmosphere;

[0066] (4) The slurry obtained after the reaction is transferred to a suction filtration bottle for filtration, and washed with sodium hydroxide solution and deionized water for 5 times. The obtained solid material is transferred to an oven and fully dried at 100°C to obtain a highly dispersed modified lithium-rich manganese-based precursor.

[0067] Example 4

[0068] This embodiment provides a modified lithium-rich manganese-based precursor and a preparation method thereof. The preparation method is the same as that of Example 1 except that the sodium dodecyl sulfate in step (2) is replaced with an equal mass of hexadecyltrimethylammonium bromide. Therefore, the remaining steps and conditions are the same as those of Example 1 and are not described in detail here.

[0069] Example 5

[0070] This embodiment provides a modified lithium-rich manganese-based precursor and a preparation method thereof. The preparation method is the same as that of Example 1 except that the sodium dodecyl sulfate in step (2) is replaced with hexadecyltrimethylammonium chloride of equal mass. Therefore, no further description is given here.

[0071] Example 6

[0072] This embodiment provides a modified lithium-rich manganese-based precursor and a preparation method thereof. Except for reducing the temperature of the coprecipitation reaction in step (3) to 40° C., the remaining steps and conditions are the same as those in Example 1, so they are not repeated here.

[0073] Example 7

[0074] This embodiment provides a modified lithium-rich manganese-based precursor and a preparation method thereof. Except for reducing the pH value of the coprecipitation reaction in step (3) to 9, the remaining steps and conditions are the same as those in Example 1, so they are not described here.

[0075] Comparative Example 1

[0076] This comparative example provides a lithium-rich manganese-based precursor and a preparation method thereof. The preparation method is the same as Example 1 except that sodium lauryl sulfate is not added in step (2), and the remaining steps and conditions are the same as those in Example 1, so they are not described here in detail.

[0077] Comparative Example 2

[0078] This comparative example provides a lithium-rich manganese-based precursor and a preparation method thereof. The preparation method is the same as Example 1 except that the sodium dodecyl sulfate in step (2) is replaced with an equal mass of sodium dodecyl sulfonate. Therefore, the remaining steps and conditions are the same as those in Example 1 and are not described in detail here.

[0079] Comparative Example 3

[0080] This comparative example provides a lithium-rich manganese-based precursor and a preparation method thereof. The preparation method is the same as Example 1 except that the sodium hydroxide solution is not mixed in step (2), and the remaining steps and conditions are the same as those in Example 1, so they are not described here in detail.

[0081] Performance Testing

[0082] The lithium-rich manganese-based precursors obtained in Examples 1-7 and Comparative Examples 1-3 were subjected to particle size distribution, tap density and BET tests, respectively. The relevant test results are shown in Table 1 below.

[0083] Table 1

[0084] It can be seen from Table 1 that: (1) In combination with Examples 1-3 and Comparative Example 1, the present application adds a modifier to the base liquid, which can effectively improve the defects of the precursor particles growing closely and easily agglomerating during the reaction stage. The particle size distribution of the particles in the modified lithium-rich manganese-based precursor is relatively uniform, and the (D90-D10) / D50 inner diameter value is controlled at about 0.6, which is much smaller than the (D90-D10) / D50 inner diameter value of the unmodified one, thereby achieving the purpose of improving the dispersibility of the lithium-rich manganese-based precursor. (2) From the comparison between Examples 1, 4, 5 and Comparative Example 2, it can be seen that if the modifier is replaced with sodium dodecyl sulfate, the (D90-D10) / D50 inner diameter value can also be slightly reduced. However, compared with sodium dodecyl sulfate, hexadecyltrimethylammonium bromide and hexadecyltrimethylammonium chloride, the particle dispersibility improvement effect is not obvious, and it is unable to effectively inhibit the agglomeration and adhesion of the precursor particles during growth. In addition, the addition of modifiers to the reaction base liquid also improves the tap density and BET of the precursor to a certain extent. The increase in tap density and BET is conducive to the subsequent development of lithium-rich manganese-based positive electrode materials with stable structure and good cycle performance.

[0085] FIG1 is a SEM photograph of the modified lithium-rich manganese-based precursor obtained in Example 1, and FIG2 is a SEM photograph of the lithium-rich manganese-based precursor obtained in Comparative Example 1.

[0086] It can be seen from Figures 1-2 that the secondary particles of the lithium-rich manganese-based precursor obtained in Comparative Example 1 adhere to each other due to the presence of high Mn and are severely agglomerated, resulting in poor dispersion and overall morphology of the precursor; the modified lithium-rich manganese-based precursor secondary particles obtained in Example 1 are evenly distributed, the dispersibility is significantly improved, and the overall morphology is also improved; this shows that the addition of the modifier to the reaction base liquid effectively solves the problem of severe agglomeration and poor dispersion of the secondary particles of the lithium-rich manganese-based precursor during the growth stage.

[0087] It can be seen that the present application effectively avoids the problems of tight growth, easy agglomeration, and poor morphology of the current lithium-rich manganese precursor during the reaction stage by adding a specific type of modifier to the reaction base liquid, thereby obtaining a modified lithium-rich manganese-based precursor with high dispersion and uniform particle distribution, thereby improving the structural stability and cycle performance of the subsequently obtained lithium-rich manganese-based material.

[0088] In addition, the preparation method provided in this application only requires adding a modifier to the reaction base liquid, without the need for additional feed pipelines, which simplifies the process flow, reduces production difficulty and operating costs, and is conducive to industrial production applications.

[0089] The applicant declares that the above is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Technical personnel in the relevant technical field should understand that any changes or substitutions that can be easily thought of by technical personnel in the relevant technical field within the technical scope disclosed in this application fall within the protection scope and disclosure scope of this application.

Claims

1. A method for preparing a modified lithium-rich manganese-based precursor, the preparation method comprising the following steps: (1) mixing a modifier, a complexing agent, an alkali solution and water to obtain a reaction base solution; (2) adding a nickel-cobalt-manganese mixed salt solution, a complexing agent and an alkali solution to the reaction base liquid obtained in step (1) to carry out a coprecipitation reaction, and obtaining a modified lithium-rich manganese-based precursor after solid-liquid separation; Wherein, the modifier in step (1) includes any one of sodium dodecyl sulfate, hexadecyltrimethylammonium bromide or hexadecyltrimethylammonium chloride, or a combination of at least two thereof.

2. The preparation method according to claim 1, wherein The mixing mass ratio of the modifier to water in step (1) is 1:(30-50); Optionally, the complexing agents in step (1) and step (2) independently include oxalic acid solution and / or ammonia water; Optionally, the complexing agents in step (1) and step (2) are independently oxalic acid solutions; Optionally, the mass concentration of the oxalic acid solution is 5-15 g / L.

3. The preparation method according to claim 1 or 2, wherein The alkali solution in step (1) and step (2) independently comprises sodium hydroxide solution and / or potassium hydroxide solution; Optionally, the mass fraction of the alkali solution in step (1) and step (2) is 30-35wt%; Optionally, the pH value of the reaction base solution in step (1) is 11.5-12.

4. The preparation method according to any one of claims 1 to 3, wherein: The anions in the nickel-cobalt-manganese mixed salt solution in step (2) include any one of sulfate, nitrate or chloride ions or a combination of at least two thereof; Optionally, the molar ratio of nickel, cobalt and manganese in the nickel-cobalt-manganese mixed salt solution in step (2) is set to x:y:z, then x+y+z=1, and z≥0.6; Optionally, the mass concentration of the ternary salt in the nickel-cobalt-manganese mixed salt solution in step (2) is 90-110 g / L.

5. The preparation method according to any one of claims 1 to 4, wherein: The coprecipitation reaction in step (2) is carried out in a nitrogen atmosphere; Optionally, the temperature of the coprecipitation reaction in step (2) is 50-60°C; Optionally, the pH value of the coprecipitation reaction in step (2) is 10-12; Optionally, the coprecipitation reaction in step (2) is accompanied by stirring at a stirring rate of 400-800 rpm.

6. The preparation method according to any one of claims 1 to 5, wherein: The solid-liquid separation in step (2) comprises any one of centrifugation, filtration or suction filtration; Optionally, the solid-liquid separation in step (2) is suction filtration; Optionally, step (2) further comprises washing and drying in sequence after the solid-liquid separation; Optionally, the washing method includes: washing with alkaline solution and deionized water for 2-5 times in sequence; Optionally, the drying temperature is 100-150°C.

7. The preparation method according to any one of claims 1 to 6, wherein: The preparation method comprises the following steps: (1) mixing a modifier, a complexing agent, an alkali solution and water to obtain a reaction base solution with a pH value of 11.5-12; the modifier comprises any one of sodium dodecyl sulfate, hexadecyltrimethylammonium bromide or hexadecyltrimethylammonium chloride or a combination of at least two thereof, and the mixing mass ratio of the modifier to water is 1:(30-50); (2) adding a nickel-cobalt-manganese mixed salt solution, a complexing agent and an alkali solution to the reaction base liquid obtained in step (1), carrying out a coprecipitation reaction in a nitrogen atmosphere, filtering, washing and drying to obtain a modified lithium-rich manganese-based precursor; the anions in the nickel-cobalt-manganese mixed salt solution include any one of sulfate, nitrate or chloride ions or a combination of at least two thereof, and the element molar ratio of nickel, cobalt and manganese in the nickel-cobalt-manganese mixed salt solution is set to x:y:z, then x+y+z=1, and z≥0.6; the mass concentration of the ternary salt in the nickel-cobalt-manganese mixed salt solution is 90-110 g / L; the temperature of the coprecipitation reaction is 50-60°C, and the pH value is 10-12; the coprecipitation reaction is accompanied by stirring, and the stirring rate is 400-800 rpm; the washing method includes: using an alkali solution and deionized water for 2-5 times; the drying temperature is 100-150°C; Wherein, the complexing agents in step (1) and step (2) independently include oxalic acid solution with a mass concentration of 5-15 g / L, and the alkali solution independently includes sodium hydroxide solution and / or potassium hydroxide solution, and the mass fraction of the alkali solution is 30-35 wt%.

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

9. A lithium-rich manganese-based positive electrode material, which is prepared by mixing and sintering the modified lithium-rich manganese-based precursor according to claim 8 with a lithium source.

10. A lithium-ion battery, wherein the positive electrode material of the lithium-ion battery is the lithium-rich manganese-based positive electrode material as claimed in claim 9.

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