An aluminum-manganese-nickel co-doped cobalt carbonate precursor, a preparation method and use thereof

Abstract

The application provides an aluminum-manganese-nickel co-doped cobalt carbonate precursor and a preparation method and use thereof. The preparation method comprises the following steps: mixing a cobalt-aluminum mixed salt solution, a manganese salt solution, a nickel salt solution and a precipitant solution, and performing a co-precipitation reaction to obtain the aluminum-manganese-nickel co-doped cobalt carbonate precursor; wherein the cobalt-aluminum mixed salt solution comprises a complexing agent; the manganese salt solution comprises a first surfactant and a second surfactant, the first surfactant comprises a crown ether surfactant, and the second surfactant comprises a non-ionic surfactant. The preparation method provided by the application realizes uniform doping of aluminum, manganese and nickel in the cobalt carbonate precursor material, not only reduces the risk of low capacity caused by only increasing the aluminum content, but also reduces the risk of small particle explosion in the reaction process, so that the obtained tricobalt tetraoxide precursor material has uniform particle size and uniform distribution of doped elements.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion batteries, and relates to an aluminum-manganese-nickel co-doped cobalt carbonate precursor and a preparation method and use thereof. BACKGROUND

[0002] As an adaptation to the development of electrochemical energy storage devices and to meet the increasing demand of humans for sustainable energy, lithium ion batteries have attracted great attention due to their low cost, high operating voltage, large battery release volume, recyclability and other advantages. The cobalt trioxide product is mainly used for the preparation of lithium cobaltate, a positive material for lithium ion batteries. With the increasing demand for lithium ion secondary batteries, the market demand for cobalt trioxide powder has also increased exponentially. At the same time, with the continuous development of 3C product functions, high-voltage lithium ion batteries are favored by the market, and the quality of cobalt trioxide needs to be strictly controlled to produce high-voltage lithium ion batteries. The purity of the battery cobalt trioxide is relatively high, and its physical energy such as tap density, particle size distribution, crystal morphology, electrochemical stability and thermal stability are also required.

[0003] In the prior art, aluminum-doped cobalt trioxide is usually prepared by solid-phase high-temperature calcination or liquid-phase coprecipitation. Among them, the solid-phase high-temperature calcination method has the defects of high energy consumption, high requirement for equipment, complex calcination process, and uneven bulk doping, so its application range is limited. The liquid-phase coprecipitation method is one of the commonly used methods for preparing battery material precursors, which has good reproducibility and relatively low energy consumption. For example, CN103746114A provides a preparation method of lithium cobaltate positive material, which relates to a positive material for lithium ion secondary batteries. A cobalt salt solution and a precipitant solution are prepared, and a cobalt carbonate precursor is precipitated by controlling the crystallization process. The cobalt carbonate precursor requires a median diameter D50 of 13-20 μm and a consistency of 0.40-0.50. The cobalt trioxide is obtained by sintering the cobalt carbonate. The cobalt trioxide, additives and lithium compounds are mixed and sintered to obtain a product. After powdering and sieving, the lithium cobaltate semi-finished product with a D50 of 13-20 μm and a consistency of 0.45-0.55 is obtained. The lithium compound and the coating element M are mixed, and then added to the ball mill together with the obtained lithium cobaltate semi-finished product. The mixed material is sintered, and the sintered product is powdered and sieved to obtain the lithium cobaltate positive material. However, due to the different solubility products of various elements, the settling speed difference is too large, resulting in uneven distribution of the doping elements in the main material.

[0004] CN108373175A discloses an aluminum-doped cobaltosic oxide and a preparation method and application thereof, specifically discloses that an aluminum salt is mixed with a complexing agent to obtain a solution, then a cobalt salt solution, a precipitant solution containing carbonate ions and the above mixed solution are added into a reaction device in a parallel flow manner to co-precipitate to obtain aluminum-doped cobalt carbonate; the aluminum-doped cobalt carbonate is calcined to obtain the aluminum-doped cobaltosic oxide. The method overcomes the problem of large difference in settling speed of various elements in the process of preparing the aluminum-doped cobaltosic oxide by a conventional liquid-phase co-precipitation method through the parallel flow feeding manner. However, the cobaltosic oxide prepared by the method has low tap density and poor particle size uniformity, which affects the electrochemical performance.

[0005] Therefore, how to improve the particle size uniformity and element doping uniformity of the cobaltosic oxide precursor material is currently in urgent need of research. SUMMARY

[0006] In view of the deficiencies in the prior art, the purpose of the present application is to provide an aluminum-manganese-nickel co-doped cobalt carbonate precursor and a preparation method and application thereof. The preparation method provided by the present application realizes uniform doping of aluminum, manganese and nickel in the cobalt carbonate precursor material, not only reduces the risk of low capacity caused by only increasing the aluminum content, but also reduces the risk of explosion of small particles in the reaction process, so that the obtained cobaltosic oxide precursor material has uniform particle size and uniform distribution of doping elements, and the preparation method provided by the present application is simple to operate and can realize industrial large-scale production.

[0007] To achieve this purpose, the present application adopts the following technical solutions:

[0008] In a first aspect, the present application provides a preparation method of an aluminum-manganese-nickel co-doped cobalt carbonate precursor, which comprises the following steps:

[0009] mixing a cobalt-aluminum mixed salt solution, a manganese salt solution, a nickel salt solution and a precipitant solution to perform a co-precipitation reaction to obtain the aluminum-manganese-nickel co-doped cobalt carbonate precursor;

[0010] The cobalt-aluminum mixed salt solution contains a complexing agent; the manganese salt solution contains a first surfactant and a second surfactant, the first surfactant contains a crown ether surfactant, and the second surfactant contains a non-ionic surfactant.

[0011] The preparation method provided by the present application avoids the segregation of Al elements by adding a complexing agent in the aluminum salt, and the segregation of manganese ions in the reaction process by adding a surfactant in the manganese salt, thereby improving the uniform dispersion of manganese elements in the final product, and the prepared cobalt carbonate precursor particles are not easy to coalesce, the size is controllable, and the dispersibility is good, which not only reduces the risk of low capacity caused by the increase of aluminum content, but also reduces the risk of small particle explosion in the reaction process, so that the obtained cobalt trioxide precursor material has uniform particle size and uniform distribution of doped elements, can effectively improve the cycle performance of lithium cobalt oxide in a high pressure environment, and can significantly improve the capacity of lithium ion batteries, and the preparation method is simple to operate and can realize large-scale industrial production.

[0012] In the present application, if all the preparation raw materials are not separately fed, the uniform distribution of aluminum, manganese and nickel in the cobalt carbonate precursor material cannot be achieved, and the uniformity of the particle size will also be affected.

[0013] The following is a preferred technical solution of the present application, but is not a limitation on the technical solutions provided by the present application. Through the following preferred technical solution, the technical purpose and beneficial effects of the present application can be better achieved and realized.

[0014] Preferably, the molar ratio of aluminum and complexing agent in the cobalt-aluminum mixed salt solution is 8:(1-2), for example 8:1, 8:1.1, 8:1.2, 8:1.3, 8:1.4, 8:1.5, 8:1.6, 8:1.7, 8:1.8, 8:1.9 or 8:2, etc., but not limited to the listed values, other values not listed in this range are also applicable.

[0015] In the present application, the molar ratio of aluminum and complexing agent is 8:(1-2), and the addition of an appropriate amount of complexing agent can adjust the hydrolysis degree of metal ions in the solution, thereby controlling the formation speed and morphology of the precipitate.

[0016] Preferably, the total concentration of cobalt ions and aluminum ions in the cobalt-aluminum mixed salt solution is 110-150 g / L and does not include 110 g / L, for example 115 g / L, 120 g / L, 125 g / L, 130 g / L, 135 g / L, 140 g / L, 145 g / L or 150 g / L, etc., but not limited to the listed values, other values not listed in this range are also applicable.

[0017] Preferably, the concentration of cobalt ions in the cobalt-aluminum mixed salt solution is 110-130 g / L, for example 110 g / L, 115 g / L, 120 g / L, 125 g / L or 130 g / L, etc., but not limited to the listed values, other values not listed in this range are also applicable.

[0018] Preferably, the mass ratio of the first surfactant, the second surfactant and the manganese in the manganese salt solution is (0.01-0.06):(0.03-0.08):1, for example 0.01:0.03:1, 0.01:0.04:1, 0.01:0.05:1, 0.01:0.06:1, 0.01:0.07:1, 0.01:0.08:1, 0.03:0.04:1, 0.03:0.04:1, 0.03:0.04:1, 0.06:0.04:1, 0.06:0.04:1, 0.06:0.04:1, 0.08:0.04:1, 0.08:0.04:1, 0.08:0.04:1, 0.06:0.08:1, 0.06:0.05:1, 0.06:0.05:1 or 0.06:0.05:1, etc., but not only limited to the listed values, other values not listed in the range are also applicable.

[0019] In the present application, the mass ratio of the first surfactant, the second surfactant and the manganese in the manganese salt solution is (0.01-0.06):(0.03-0.08):1, that is, the uniform doping of manganese can be achieved, and the agglomeration of material particles can be avoided.

[0020] Preferably, the content of manganese ions in the manganese salt solution is 1000-3000 ppm, for example 1000 ppm, 1300 ppm, 1500 ppm, 1800 ppm, 2000 ppm, 2300 ppm, 2500 ppm, 2800 ppm or 3000 ppm, etc., but not only limited to the listed values, other values not listed in the range are also applicable.

[0021] Preferably, the content of nickel ions in the nickel salt solution is 3000-5000 ppm, for example 3000 ppm, 3300 ppm, 3500 ppm, 3800 ppm, 4000 ppm, 4300 ppm, 4500 ppm, 4800 ppm or 5000 ppm, etc., but not only limited to the listed values, other values not listed in the range are also applicable.

[0022] Preferably, the feeding speed of the cobalt-aluminum mixed salt solution is 15-35 L / h, for example 15 L / h, 20 L / h, 25 L / h, 30 L / h or 35 L / h, etc., but not only limited to the listed values, other values not listed in the range are also applicable.

[0023] Preferably, the feeding speed of the manganese salt solution is 0.2-1 L / h, for example 0.2 L / h, 0.3 L / h, 0.4 L / h, 0.5 L / h, 0.6 L / h, 0.7 L / h, 0.8 L / h, 0.9 L / h, or 1 L / h, etc., but not limited to the listed values, and other values not listed in the range are also applicable.

[0024] Preferably, the feeding speed of the nickel salt solution is 0.5-2 L / h, for example 0.5 L / h, 0.6 L / h, 0.7 L / h, 0.8 L / h, 0.9 L / h, 1 L / h, 1.1 L / h, 1.2 L / h, 1.3 L / h, 1.4 L / h, 1.5 L / h, 1.6 L / h, 1.7 L / h, 1.8 L / h, 1.9 L / h, or 2 L / h, etc., but not limited to the listed values, and other values not listed in the range are also applicable.

[0025] In the present application, the feeding flow rate of the manganese salt solution and the feeding flow rate of the nickel salt solution are regulated, which can better control the doping content of manganese and nickel elements, thereby achieving significant improvement in battery performance, including improving energy density, cycle life, and energy storage efficiency of the battery, and adapting to the demand for high-performance batteries in different fields.

[0026] Preferably, the pH value of the co-precipitation reaction is 7-8, for example 7, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, or 8, etc., but not limited to the listed values, and other values not listed in the range are also applicable.

[0027] Preferably, the reaction temperature of the co-precipitation reaction is 40-45℃, for example 40℃, 41℃, 42℃, 43℃, 44℃, or 45℃, etc., but not limited to the listed values, and other values not listed in the range are also applicable.

[0028] Preferably, the stirring speed of the co-precipitation reaction is 180-220 rpm, for example 180 rpm, 190 rpm, 200 rpm, 210 rpm, or 220 rpm, etc., but not limited to the listed values, and other values not listed in the range are also applicable.

[0029] Preferably, the product of the co-precipitation reaction is washed and dried.

[0030] Preferably, the D50 of the aluminum-manganese-nickel co-doped cobalt carbonate precursor is 15-20 μm, for example 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm, etc., but not limited to the listed values, and other values not listed in the range are also applicable.

[0031] The D50 of the aluminum-manganese-nickel co-doped cobalt carbonate precursor in the application is the reactor shutdown particle size.

[0032] As a preferred technical solution, the preparation method comprises the following steps:

[0033] The cobalt-aluminum mixed salt solution with a total concentration of 110-150 g / L of cobalt ions and aluminum ions, the manganese salt solution with a content of 1000-3000 ppm of manganese ions, the nickel salt solution with a content of 3000-5000 ppm of nickel ions, and the precipitant solution are mixed, the feeding speed of the manganese salt solution is 0.2-1 L / h, the feeding speed of the nickel salt solution is 0.5-2 L / h, and the co-precipitation reaction is carried out in an environment with a pH value of 7-8 to obtain the aluminum-manganese-nickel co-doped cobalt carbonate precursor.

[0034] The cobalt-aluminum mixed salt solution comprises a complexing agent, and the molar ratio of aluminum to the complexing agent is 8:(1-2); the manganese salt solution comprises a first surfactant and a second surfactant, and the mass ratio of the first surfactant, the second surfactant, and manganese in the manganese salt is (0.01-0.06):(0.03-0.08):1, the first surfactant comprises a crown ether surfactant, and the second surfactant comprises a non-ionic surfactant.

[0035] It should be noted that, in addition to the above-mentioned characteristic limitations, the specific substance types, preparation parameters, and preparation processes in the preparation process are all conventional technical solutions.

[0036] Optionally, the co-precipitation reaction can be carried out in a bottom solution, and the precipitant solution is used as the reaction bottom solution, and the concentration of the precipitant solution is 160-220 g / L, for example, 160 g / L, 170 g / L, 180 g / L, 190 g / L, 200 g / L, 210 g / L, or 220 g / L, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0037] Optionally, the precipitant includes but is not limited to at least one of sodium bicarbonate, sodium hydroxide, or sodium carbonate.

[0038] Optionally, the types of salt solutions in the preparation raw materials include but are not limited to at least one of sulfate, chloride, nitrate, or acetate.

[0039] Optionally, the washing uses an ammonium bicarbonate solution, and the concentration of the ammonium bicarbonate in the washing process is 40-60 g / L, for example, 40 g / L, 45 g / L, 50 g / L, 55 g / L, or 60 g / L, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0040] Optionally, the crown ether surfactant includes, but is not limited to, at least one of 18-crown-6, dibenzo-18-crown-6 or 15-crown-5.

[0041] Optionally, the non-ionic surfactant includes, but is not limited to, a non-ionic surfactant of HL-610 type.

[0042] In a second aspect, the present application provides an aluminum-manganese-nickel co-doped cobalt carbonate precursor, which is prepared by the preparation method in the first aspect.

[0043] In a third aspect, the present application provides a tricobalt tetraoxide precursor, which is obtained by calcining the aluminum-manganese-nickel co-doped cobalt carbonate precursor in the second aspect.

[0044] In the present application, the method for obtaining tricobalt tetraoxide by calcining the aluminum-manganese-nickel co-doped cobalt carbonate precursor is a conventional technical solution, and the calcination process can be adaptively selected and adjusted by the person skilled in the art according to actual needs.

[0045] Specifically, the calcination can be one-stage calcination or staged calcination.

[0046] Optionally, the temperature of the one-stage calcination is 600-750℃, for example, 600℃, 650℃, 700℃ or 750℃, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0047] Optionally, the temperature of the one-stage calcination is 600-750℃, for example, 600℃, 650℃, 700℃ or 750℃, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0048] Optionally, the temperature of the one-stage calcination is 600-750℃, for example, 600℃, 650℃, 700℃ or 750℃, etc., but is not limited to the listed values, and other values not listed in this range are also applicable.

[0049] In a fourth aspect, the present application provides a lithium cobaltate positive electrode material, which is obtained by mixing and sintering the tricobalt tetraoxide precursor in the third aspect with a lithium source.

[0050] In a fifth aspect, the present application further provides a lithium ion battery, which includes the lithium cobaltate positive electrode material in the fourth aspect.

[0051] Compared with the prior art, the present application has the following beneficial effects:

[0052] The preparation method provided by the present application avoids segregation of Al elements by separately feeding raw materials and adding a complexing agent in the aluminum salt, and the surface active agent added in the manganese salt can effectively avoid segregation of manganese ions during the reaction process, thereby improving the uniform dispersion degree of manganese elements in the final product, and synergistically making the prepared cobalt carbonate precursor particles not easy to coalesce, controllable in size, and good in dispersibility, thereby not only reducing the risk of low capacity caused by only increasing the aluminum content, but also reducing the risk of explosion of small particles during the reaction process, so that the obtained cobalt trioxide tetroxide precursor material has uniform particle size and uniform distribution of doped elements, can effectively improve the cycle performance of lithium cobalt oxide in a high-pressure environment, and can significantly improve the capacity of a lithium ion battery, and the preparation method is simple to operate and can realize large-scale industrial production. DETAILED DESCRIPTION

[0053] The technical solutions of the present application will be further described below through specific examples. Those skilled in the art should understand that the examples are only for the purpose of understanding the present application and should not be regarded as specific limitations of the present application.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application; the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion.

[0055] In the description of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically defined.

[0056] Example 1

[0057] The present embodiment provides an aluminum-manganese-nickel co-doped cobalt carbonate precursor, and a preparation method of the aluminum-manganese-nickel co-doped cobalt carbonate precursor is as follows:

[0058] (1) cobalt-aluminum mixed salt solution (concentration of 120 g / L) prepared by mixing cobalt salt (cobalt sulfate) solution and aluminum salt (aluminum sulfate) solution (concentration of cobalt ions is 110 g / L), the cobalt-aluminum mixed salt solution further contains tartar complexing agent (molar ratio of tartar complexing agent to aluminum is 1:8), nickel ion solution (3000 ppm of nickel salt solution, nickel sulfate) is prepared, manganese ion solution (1000 ppm of manganese salt solution, manganese sulfate) is prepared, the manganese salt solution contains dibenzo-18-crown-6 and HL-610 non-ionic surfactant (mass ratio of dibenzo-18-crown-6 to HL-610 non-ionic surfactant to manganese is 0.01:0.03:1), and ammonium bicarbonate solution (concentration of 160 g / L) is prepared as a reaction base solution (precipitant solution);

[0059] (2) the reaction kettle is 1.5 L in size, and the ammonium bicarbonate solution is added as a base solution in the reaction kettle, the volume ratio of the base solution in the reaction kettle is 40%, and the pH of the base solution is 7.4;

[0060] Then, the cobalt-aluminum mixed salt solution, the manganese salt solution and the manganese salt solution are added into the base solution in parallel flow to perform a co-precipitation reaction.

[0061] The pH value of the nucleation stage of the reaction is controlled in the range of 7.4-8.6 (the particle size D50 reaches 4 μm, and the nucleation stage of the reaction ends), the pH value of the particle growth stage is maintained at about 7.1, the reaction temperature is 42 ℃, the rotation speed is 220 rpm, the feeding speed of the cobalt-aluminum mixed salt solution is set to 20 L / h, the feeding speed of the nickel salt is set to 0.5 L / h, and the feeding speed of the mixed manganese salt is set to 0.2 L / h.

[0062] After the D50 of the aluminum-manganese-nickel co-doped cobalt carbonate reaches 16 μm, the reaction is stopped, the obtained aluminum-manganese-nickel co-doped cobalt carbonate precursor is washed with a dilute ammonium carbonate (ammonium bicarbonate) solution with a concentration of 40 g / L, and after the washing is completed, the aluminum-manganese-nickel co-doped cobalt carbonate precursor material is dried in an oven at 110 ℃ to obtain the aluminum-manganese-nickel co-doped cobalt carbonate precursor material.

[0063] The embodiment also provides an aluminum-manganese-nickel co-doped tricobalt tetraoxide, and a preparation method of the tricobalt tetraoxide is as follows:

[0064] The aluminum-manganese-nickel co-doped tricobalt tetraoxide is obtained by heating the prepared aluminum-manganese-nickel co-doped cobalt carbonate precursor material to a calcination temperature of 750 ℃ at a heating rate of 8 ℃ / min and maintaining the temperature for 90 min.

[0065] Example 2

[0066] The embodiment provides an aluminum-manganese-nickel co-doped cobalt carbonate precursor, and a preparation method of the aluminum-manganese-nickel co-doped cobalt carbonate precursor is as follows:

[0067] (1) Prepare a cobalt-aluminum mixed salt solution (cobalt ion concentration: 130 g / L) by mixing a cobalt salt (cobalt sulfate) solution and an aluminum salt (aluminum sulfate) solution at a mixing concentration of 150 g / L, and add a tartaric acid complexing agent (molar ratio of tartaric acid complexing agent to aluminum: 2:8) to the cobalt-aluminum mixed salt solution; prepare a nickel salt solution with a nickel ion concentration of 5000 ppm; prepare a manganese salt solution with a manganese ion concentration of 3000 ppm, and add dibenzo-18-crown-6 and HL-610 non-ionic surfactant (mass ratio of dibenzo-18-crown-6 to HL-610 non-ionic surfactant to manganese: 0.06:0.08:1) to the manganese salt solution; and prepare an ammonium bicarbonate solution (precipitant solution) with a concentration of 220 g / L as a reaction base solution;

[0068] (2) In a reaction kettle with a nitrogen atmosphere and a pressure of 0.3 MPa, the size of the reaction kettle is 1.5 L, and an ammonium bicarbonate solution is added as a base solution, the volume fraction of the base solution in the reaction kettle is 45%, and the pH of the base solution is 7.5;

[0069] Then the cobalt-aluminum mixed salt solution, the manganese salt solution, and the manganese salt solution are added to the base solution in parallel flow to perform a co-precipitation reaction.

[0070] The pH value of the reaction nucleation stage is controlled in the range of 7.4-8.6 (the particle size D50 reaches 4 μm, and the reaction nucleation stage ends), the pH value of the particle growth stage is maintained at about 7.2, the reaction temperature is 40°C, the rotation speed is 180 rpm, the feeding speed of the cobalt-aluminum mixed salt solution is set to 35 L / h, the feeding speed of the nickel salt is set to 2 L / h, and the feeding speed of the mixed manganese salt is set to 1 L / h;

[0071] After the D50 of the aluminum-manganese-nickel co-doped cobalt carbonate reaches 20 μm, the reaction is stopped; and the obtained aluminum-manganese-nickel co-doped cobalt carbonate precursor is washed with a dilute ammonium carbonate (ammonium bicarbonate) solution with a concentration of 50 g / L, and is dried in an oven at 110°C after the washing is completed, to obtain an aluminum-manganese-nickel co-doped cobalt carbonate precursor material.

[0072] The present embodiment also provides an aluminum-manganese-nickel co-doped tricobalt tetraoxide, and a preparation method of the tricobalt tetraoxide is as follows:

[0073] The aluminum-manganese-nickel co-doped cobalt carbonate precursor material prepared is heated to a calcination temperature of 700°C at a heating rate of 10°C / min, and is kept at the temperature for 150 min, to obtain the aluminum-manganese-nickel co-doped tricobalt tetraoxide.

[0074] Example 3

[0075] The present embodiment provides an aluminum-manganese-nickel co-doped cobalt carbonate precursor, and a preparation method of the aluminum-manganese-nickel co-doped cobalt carbonate precursor is as follows:

[0076] (1) Prepare a cobalt-aluminum mixed salt solution (cobalt ion concentration: 120 g / L) by mixing a cobalt salt (cobalt sulfate) solution and an aluminum salt (aluminum sulfate) solution at a mixing concentration of 130 g / L, and add a tartaric acid complexing agent (molar ratio of tartaric acid complexing agent to aluminum: 1.5:8) to the cobalt-aluminum mixed salt solution; prepare a nickel salt solution with a nickel ion concentration of 4000 ppm; prepare a manganese salt solution with a manganese ion concentration of 2000 ppm, and add 18-crown-6 and HL-610 non-ionic surfactants (mass ratio of 18-crown-6 to HL-610 non-ionic surfactant to manganese: 0.01:0.03:1) to the manganese salt solution; and prepare an ammonium bicarbonate solution (precipitant solution) with a concentration of 160 g / L as a reaction base solution;

[0077] (2) In a reaction kettle with a nitrogen atmosphere and a pressure of 0.3 MPa, the size of the reaction kettle is 2 L, and an ammonium bicarbonate solution is added as a base solution, the volume fraction of the base solution in the reaction kettle is 45%, and the pH of the base solution is 7.4;

[0078] Then the cobalt-aluminum mixed salt solution, the manganese salt solution, and the manganese salt solution are added to the base solution in parallel flow to perform a co-precipitation reaction.

[0079] The pH value of the nucleation stage of the reaction is controlled to be in the range of 7.4-8.6 (the particle size D50 reaches 4.5 μm, and the nucleation stage of the reaction ends), the pH value of the particle growth stage is maintained at about 7.1, the reaction temperature is 42°C, the rotation speed is 220 rpm, the feeding speed of the cobalt-aluminum mixed salt solution is set to be 25 L / h, the feeding flow of the nickel salt is set to be 1 L / h, and the feeding flow of the mixed manganese salt is set to be 0.5 L / h;

[0080] After the D50 of the aluminum-manganese-nickel co-doped cobalt carbonate reaches 18 μm, the reaction is stopped; and the obtained aluminum-manganese-nickel co-doped cobalt carbonate precursor is washed with a dilute ammonium carbonate (ammonium bicarbonate) solution with a concentration of 40 g / L, and is dried in an oven at 110°C after the washing is completed, to obtain an aluminum-manganese-nickel co-doped cobalt carbonate precursor material.

[0081] The embodiment also provides an aluminum-manganese-nickel co-doped tricobalt tetraoxide, and a preparation method of the tricobalt tetraoxide is as follows:

[0082] The aluminum-manganese-nickel co-doped cobalt carbonate precursor material prepared is heated to a calcination temperature of 750°C at a heating rate of 8°C / min, and is kept at the temperature for 90 min, to obtain the aluminum-manganese-nickel co-doped tricobalt tetraoxide.

[0083] Example 4

[0084] The difference between the embodiment and example 1 is that in step (1) of the embodiment, the molar ratio of the tartaric acid complexing agent to aluminum is 3:8.

[0085] The rest of the preparation method and parameters are consistent with Example 1.

[0086] Example 5

[0087] The difference between this example and Example 1 is that the feeding flow rate of the nickel salt solution in step (2) of this example is 2.5 L / h.

[0088] The rest of the preparation method and parameters are consistent with Example 1.

[0089] Example 6

[0090] The difference between this example and Example 1 is that the feeding flow rate of the manganese salt solution in step (2) of this example is 0.3 L / h.

[0091] The rest of the preparation method and parameters are consistent with Example 1.

[0092] Example 7

[0093] The difference between this example and Example 1 is that the feeding flow rate of the manganese salt solution in step (2) of this example is 1.5 L / h.

[0094] The rest of the preparation method and parameters are consistent with Example 1.

[0095] Example 8

[0096] The difference between this example and Example 1 is that the feeding flow rate of the manganese salt solution in step (2) of this example is 0.1 L / h.

[0097] The rest of the preparation method and parameters are consistent with Example 1.

[0098] Comparative Example 1

[0099] The difference between this example and Example 1 is that in step (1) of this example, the mixed salt solution is obtained by directly mixing cobalt sulfate, aluminum sulfate, nickel sulfate and manganese sulfate, and the mixed salt solution also includes tartaric acid complexing agent, dibenzo-18 crown-6 and HL-610 non-ionic surfactant. The concentration of cobalt ions in the mixed salt solution is 110 g / L, the concentration of cobalt-aluminum mixed ions is 120 g / L, the molar ratio of tartaric acid complexing agent to aluminum is 1:8, the concentration of nickel ions is 3000 ppm, the concentration of manganese ions is 1000 ppm, and the mass ratio of dibenzo-18 crown-6 and HL-610 non-ionic surfactant to manganese is 0.01:0.03:1.

[0100] The rest of the preparation method and parameters are consistent with Example 1.

[0101] Comparative Example 2

[0102] The difference between the present comparative example and Example 1 is that the cobalt-aluminum mixed salt solution in step (1) of the present comparative example does not contain a complexing agent.

[0103] The remaining preparation methods and parameters are consistent with those of Example 1.

[0104] Comparative Example 3

[0105] The difference between the present comparative example and Example 1 is that the manganese salt solution in step (1) of the present comparative example does not contain dibenzo-18-crown-6.

[0106] The remaining preparation methods and parameters are consistent with those of Example 1.

[0107] Comparative Example 4

[0108] The difference between the present comparative example and Example 1 is that the manganese salt solution in step (1) of the present comparative example does not contain HL-610 non-ionic surfactant.

[0109] The remaining preparation methods and parameters are consistent with those of Example 1.

[0110] [Preparation of batteries and performance testing]

[0111] Battery preparation:

[0112] The cobalt trioxide tetrachloride precursor material and lithium carbonate provided by Examples 1-8 and Comparative Examples 1-4 were weighed according to a lithium cobalt molar ratio of 1.025, mixed, and sintered in an air atmosphere at 1100°C for 9h in a box furnace; the once-sintered product after sintering was ground, iron was removed, and sieved to obtain a lithium cobalt oxide material;

[0113] 80wt% of the positive electrode active material (lithium cobalt oxide prepared by Examples 1-8 and Comparative Examples 1-4 was used as the positive electrode active material), 10wt% of Super-P, and 10wt% of polyvinylidene fluoride (PVDF) were dispersed in an N-methyl pyrrolidone (NMP) solution to prepare an electrode slurry, which was coated on an aluminum foil and dried to obtain a positive electrode;

[0114] A lithium sheet was used as the negative electrode;

[0115] The separator was a Φ19 PP microporous membrane (Celgard 2400);

[0116] The electrolyte was composed of a mixture of 1M LiPF6 and EC, DMC, and EMC (EC: DMC: EMC volume ratio = 1:1:1).

[0117] The above positive electrode, separator, negative electrode, and electrolyte were assembled to obtain a coin cell.

[0118] The lithium ion batteries provided by examples 1-8 and comparative examples 1-4 are subjected to performance tests under the following conditions: 3.0-4.48V, current density IC = 180mAh / g, test temperature is 25±1℃, and the discharge capacity and cycle performance of the lithium ion batteries are tested, and the test results are shown in Table 1.

[0119] Table 1

[0120]

[0121] From Table 1, it can be seen that:

[0122] From the data results of examples 1 and 4, it can be seen that if the molar ratio of the complexing agent to aluminum is too large, more aluminum ions are complexed, so that the reaction is not complete. In this case, the morphology of the precursor becomes loose, and the tap density decreases. In addition, the excess complexing agent will also cause the complexed metal ions to be discharged with the supernatant, causing waste of raw materials, and also increasing the difficulty of subsequent wastewater treatment.

[0123] From the data results of examples 1 and 5-8, it can be seen that by adjusting the feed flow of the nickel salt solution and the manganese salt solution, the content of manganese and nickel elements can be better controlled, so as to realize the significant improvement of the battery performance, including improving the energy density, cycle life, and energy storage efficiency of the battery, and adapting to the needs of high-performance batteries in different fields; and too large or too small feed flow will lead to unstable doping amount and uneven distribution of doped elements in the precursor.

[0124] From the data results of examples 1 and comparative examples 1, it can be seen that if separate feeding is not performed, due to the different precipitation rates of each element, the doping content of the doped elements cannot be accurately controlled, which in turn affects the discharge capacity.

[0125] From the data results of examples 1 and comparative examples 2-4, it can be seen that during the separate feeding process, if the complexing agent and the first and second surfactants are not added simultaneously, the high tap density, good particle dispersion, and the effect of controlling the growth and morphology of the particles cannot be achieved.

[0126] In summary, the preparation method provided by the present application avoids segregation of Al elements by separately feeding raw materials and adding a complexing agent in the aluminum salt, and the surface active agent added in the manganese salt can effectively avoid segregation of manganese ions during the reaction process, improve the uniform dispersion degree of manganese elements in the final product, and cooperate to make the prepared cobalt carbonate precursor particles not easy to coalesce, controllable in size, and good in dispersibility, not only reducing the risk of low capacity caused by only increasing the aluminum content, but also reducing the risk of small particle explosion during the reaction process, so that the obtained cobalt tetraoxide precursor material has uniform particle size and uniform distribution of doped elements, can effectively improve the cycle performance of lithium cobalt oxide in a high-pressure environment, and can significantly improve the capacity of lithium ion batteries, and the preparation method is simple to operate and can realize industrial large-scale production.

[0127] The applicant declares that the above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and those skilled in the art should understand that any changes or replacements within the technical scope disclosed by the present application can be easily thought of by any person skilled in the art, and all fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing an aluminum-manganese-nickel co-doped cobalt carbonate precursor, characterized in that, The preparation method includes the following steps: A cobalt-aluminum mixed salt solution, a manganese salt solution, a nickel salt solution, and a precipitant solution are mixed and subjected to a coprecipitation reaction to obtain the aluminum-manganese-nickel co-doped cobalt carbonate precursor. The cobalt-aluminum mixed salt solution includes a complexing agent; the manganese salt solution includes a first surfactant and a second surfactant, wherein the first surfactant includes a crown ether surfactant and the second surfactant includes a nonionic surfactant. In the cobalt-aluminum mixed salt solution, the molar ratio of aluminum to complexing agent is 8:(1~2). In the manganese salt solution, the mass ratio of the first surfactant, the second surfactant, and the manganese in the manganese salt is 0.01:(0.03~0.08):1; The feed rate of the manganese salt solution is 0.2~1L / h; The feed rate of the nickel salt solution is 0.5~2L / h.

2. The preparation method according to claim 1, characterized in that, The total concentration of cobalt and aluminum ions in the cobalt-aluminum mixed salt solution is 110~150 g / L, excluding 110 g / L, and the concentration of cobalt ions in the cobalt-aluminum mixed salt solution is 110~130 g / L.

3. The preparation method according to claim 1, characterized in that, The manganese salt solution contains 1000~3000 ppm of manganese ions.

4. The preparation method according to claim 1, characterized in that, The nickel salt solution contains 3000~5000 ppm of nickel ions.

5. The preparation method according to claim 1, characterized in that, The feed rate of the cobalt-aluminum mixed salt solution is 15~35L / h.

6. The preparation method according to claim 1, characterized in that, The pH value of the coprecipitation reaction is 7~8, the reaction temperature of the coprecipitation reaction is 40~45℃, and the stirring speed of the coprecipitation reaction is 180~220rpm.

7. The preparation method according to claim 1, characterized in that, The product of the coprecipitation reaction was washed and dried.

8. The preparation method according to claim 1, characterized in that, The D50 of the aluminum-manganese-nickel co-doped cobalt carbonate precursor is 15~20 μm.

9. The preparation method according to any one of claims 1-8, characterized in that, The preparation method includes the following steps: A co-precipitation reaction is carried out in an environment with a pH of 7-8 by mixing a cobalt-aluminum mixed salt solution with a total cobalt and aluminum ion concentration of 110-150 g / L, a manganese salt solution with a manganese ion content of 1000-3000 ppm, a nickel salt solution with a nickel ion content of 3000-5000 ppm, and a precipitant solution. The feed rate of the manganese salt solution is 0.2-1 L / h, the feed rate of the nickel salt solution is 0.5-2 L / h, and the co-precipitation reaction is carried out to obtain the aluminum-manganese-nickel co-doped cobalt carbonate precursor. The cobalt-aluminum mixed salt solution includes a complexing agent, and the molar ratio of aluminum to the complexing agent is 8:(1~2); the manganese salt solution includes a first surfactant and a second surfactant, and the mass ratio of the first surfactant, the second surfactant and manganese in the manganese salt is 0.01:(0.03~0.08):1, the first surfactant includes crown ether surfactants, and the second surfactant includes nonionic surfactants.

10. A cobalt carbonate precursor co-doped with aluminum, manganese, and nickel, characterized in that, The aluminum-manganese-nickel co-doped cobalt carbonate precursor is prepared by the preparation method according to any one of claims 1-9.

11. A cobalt tetroxide precursor, characterized in that, The cobalt tetroxide precursor is obtained by calcining the aluminum-manganese-nickel co-doped cobalt carbonate precursor as described in claim 10.

12. A lithium cobalt oxide cathode material, characterized in that, The lithium cobalt oxide cathode material is obtained by sintering the cobalt tetroxide precursor as described in claim 11 with a lithium source.

13. A lithium-ion battery, characterized in that, The lithium-ion battery includes the lithium cobalt oxide cathode material as described in claim 12.

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