A high sphericity cathode material precursor, its preparation method and application

Abstract

The present invention relates to a high sphericity cathode material precursor, a preparation method and an application thereof. The preparation method comprises the following steps: under an oxygen-containing atmosphere condition, mixing a nickel-cobalt-manganese ternary mixed salt solution, a precipitant solution, a complexing agent solution and a bottom liquid to carry out a coprecipitation reaction to obtain the high sphericity cathode material precursor; the oxygen-containing atmosphere is formed by using an oxygen-containing gas, and the volume fraction of oxygen in the oxygen-containing gas is 1 vol% to 20 vol%. By preparing the precursor under an oxygen-containing atmosphere, the precursor of the present invention has a high sphericity and a relatively high tap density, and the cathode material prepared from the precursor has good cycle stability and rate performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, relates to an electrode material, and particularly relates to a high-sphericity cathode material precursor, a preparation method thereof and an application thereof. Background Art

[0002] As a new type of green power source, lithium-ion batteries have been widely used in technical fields such as 3C digital electronic products, power tools, electric vehicles, and energy storage. Ternary cathode materials are currently a hot spot that major enterprises are competing to develop, and ternary precursors have a crucial impact on the performance of cathode materials.

[0003] Sphericity is a key dimension for evaluating precursors. High sphericity can improve the tap density, rate performance, and cycle performance of cathode materials. Therefore, it is necessary to improve the sphericity of precursors. According to reports in the prior art, when the particle size of the precursor is above 4 μm, it is easy for the precursor to have a high sphericity; when the particle size is less than 4 μm, peanut-shaped multi-headed precursors are likely to appear, resulting in poor particle sphericity.

[0004] Changing the complexing agent is one of the methods to improve the sphericity of cathode material precursors, but changing the complexing agent will lead to a switch in the system environment, which is incompatible with the current mainstream industrial wastewater treatment process and cannot be promoted and applied industrially. Although the method of adjusting the pH can improve the sphericity, the improvement degree is limited; while the seed method is too complex and not suitable for large-scale industrial production.

[0005] CN105680030A discloses a preparation method of a nickel cobalt manganese ternary cathode material precursor, which includes the following steps: preparing a nickel cobalt manganese salt solution with a metal ion concentration of 60-120 g / L, preparing a sodium hydroxide solution with a concentration of 160-240 g / L, and an ammonia water mass concentration of 10-18%; adding deionized water to a sealed reaction kettle, stirring, purging with nitrogen for protection, adding ammonia water, and adjusting the ammonia water concentration to 0.3-1 mol / L; heating to 50-70 °C, adding the nickel cobalt manganese salt solution, sodium hydroxide solution, and ammonia water into the reaction kettle simultaneously, and controlling the pH value to be 10-12, and controlling the ammonia water concentration to be 0.3-1 mol / L; after the feeding is completed, stop stirring, age for 1 hour, and remove the upper clarified mother liquor in a sealed state; stir again and repeat the precipitation until the particle size reaches the required particle size.

[0006] CN109250764A discloses a preparation method of a power-type medium-particle-size nickel cobalt manganese precursor material. The steps adopted include: preparing a nickel cobalt manganese salt solution, a sodium hydroxide solution and ammonia water; adding pure water into a sealed reaction kettle, starting stirring, heating to 50-70 °C, and purging with an inert gas for more than 2 hours; then adding the sodium hydroxide solution and ammonia water into the sealed reaction kettle to adjust the pH value and ammonia value; adding the nickel cobalt manganese salt solution, the sodium hydroxide solution and ammonia water into the reaction kettle in a parallel flow to generate a precipitate; washing the generated precipitate; and drying the washed product. Nitrogen with a large flow rate is adopted in the synthesis stage, direct contact between the material and air is avoided during the washing process, the temperature and the feeding amount are matched with each other during the drying process, and the nickel cobalt manganese precursor material is obtained after drying.

[0007] Although the above preparation method can improve the sphericity of the precursor to a certain extent, the preparation method is too complex and requires more processes. Therefore, it is necessary to provide a high-sphericity cathode material precursor with a simple process, its preparation method and application. Summary of the Invention

[0008] The purpose of the present invention is to provide a high-sphericity cathode material precursor, its preparation method and application. The preparation method prepares the precursor in an oxygen-containing atmosphere, so that the precursor has high sphericity and a relatively high tap density. The cathode material prepared from the precursor has good cycle stability and rate performance.

[0009] To achieve the purpose of this invention, the following technical solutions are adopted in the present invention:

[0010] In the first aspect, the present invention provides a preparation method of a high-sphericity cathode material precursor. The preparation method includes the following steps:

[0011] Under the condition of an oxygen-containing atmosphere, a nickel cobalt manganese ternary mixed salt solution, a precipitant solution, a complexing agent solution and a bottom liquid are mixed to carry out a coprecipitation reaction to obtain the high-sphericity cathode material precursor;

[0012] The oxygen-containing atmosphere is formed by using an oxygen-containing gas, and the volume fraction range of oxygen in the oxygen-containing gas is 1 vol% to 20 vol%.

[0013] The oxygen-containing atmosphere in the present invention is formed by using an oxygen-containing gas, and the oxygen-containing gas includes a gas with a certain volume fraction of oxygen after mixing; or at least two gases are respectively introduced so that the volume fraction range of oxygen in the oxygen-containing atmosphere of the reaction environment is 1 vol% to 20 vol%.

[0014] The oxygen-containing atmosphere in the present invention is formed by using an oxygen-containing gas, and the volume fraction of oxygen in the oxygen-containing gas ranges from 1 vol% to 20 vol%. For example, it can be 1 vol%, 3 vol%, 5 vol%, 10 vol%, 15 vol% or 20 vol%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0015] In the present invention, by preparing the precursor under an oxygen-containing atmosphere, the precursor has a high sphericity and a relatively high tap density, and the cathode material prepared from the precursor has good cycle stability and rate performance.

[0016] Preferably, during the coprecipitation reaction, the pH value is maintained in the range of 10 to 12. For example, it can be 10, 10.5, 11, 11.5 or 12, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0017] Preferably, the temperature range during the coprecipitation reaction is from 40°C to 60°C. For example, it can be 40°C, 45°C, 50°C, 55°C or 60°C, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0018] Preferably, during the coprecipitation reaction, the ammonia concentration in the system is from 4 g / L to 8 g / L. For example, it can be 4 g / L, 5 g / L, 6 g / L, 7 g / L or 8 g / L, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0019] The ammonia concentration in the system of the present invention is calculated based on NH3 in the system.

[0020] Preferably, during the coprecipitation reaction, stirring is accompanied, and the rotation speed of the stirring is from 200 r / min to 400 r / min. For example, it can be 200 r / min, 250 r / min, 300 r / min, 350 r / min or 400 r / min, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0021] Preferably, the coprecipitation reaction proceeds until the particle size D 50 reaches 2.5 μm to 3.5 μm, at which time the feeding is stopped and the coprecipitation is continued until the reaction is complete.

[0022] During the coprecipitation reaction of the present invention, the particle size D 50 at the time of stopping the feeding is 2.5 μm to 3.5 μm. For example, it can be 2.5 μm, 2.8 μm, 3 μm, 3.2 μm or 3.5 μm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0023] The high-sphericity cathode material precursor obtained by the preparation method provided by the present invention has a sphericity of ≥99% when the particle size D 50 is less than 4 μm; however, when the particle size D 50 is less than 2.5 μm at the time of stopping the feed during the coprecipitation reaction, it is likely to cause the obtained cathode material precursor to have multiple linear shapes and poor sphericity.

[0024] Preferably, the concentration of the nickel-cobalt-manganese ternary mixed salt solution is 80 g / L to 120 g / L. For example, it can be 80 g / L, 90 g / L, 100 g / L, 110 g / L, or 120 g / L, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0025] The concentration of the nickel-cobalt-manganese ternary mixed salt solution described in the present invention refers to the total concentration of nickel salt, cobalt salt, and manganese salt therein.

[0026] Exemplarily, the nickel salt includes any one or a combination of at least two of nickel nitrate, nickel sulfate, or nickel chloride. Typical but non-limiting combinations include a combination of nickel nitrate and nickel sulfate, a combination of nickel sulfate and nickel chloride, a combination of nickel nitrate and nickel chloride, or a combination of nickel nitrate, nickel sulfate, and nickel chloride.

[0027] Exemplarily, the cobalt salt includes any one or a combination of at least two of cobalt nitrate, cobalt sulfate, or cobalt chloride. Typical but non-limiting combinations include a combination of cobalt nitrate and cobalt sulfate, a combination of cobalt sulfate and cobalt chloride, a combination of cobalt nitrate and cobalt chloride, or a combination of cobalt nitrate, cobalt sulfate, and cobalt chloride.

[0028] Exemplarily, the manganese salt includes any one or a combination of at least two of manganese nitrate, manganese sulfate, or manganese chloride. Typical but non-limiting combinations include a combination of manganese nitrate and manganese sulfate, a combination of manganese sulfate and manganese chloride, a combination of manganese nitrate and manganese chloride, or a combination of manganese nitrate, manganese sulfate, and manganese chloride.

[0029] The present invention does not further limit the molar ratio of nickel, cobalt, and manganese in the nickel-cobalt-manganese ternary mixed salt solution, and those skilled in the art can make reasonable selections according to process requirements.

[0030] Preferably, during the mixing, the flow rate of the nickel-cobalt-manganese ternary mixed salt solution is 6 L / h to 10 L / h. For example, it can be 6 L / h, 7 L / h, 8 L / h, 9 L / h, or 10 L / h, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0031] Preferably, the precipitant solution is a sodium hydroxide solution with a mass concentration of 28% to 32%. For example, it can be 28%, 29%, 30%, 31%, or 32%, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0032] Preferably, during the mixing, the flow rate of the precipitant solution is 2 L / h to 3 L / h. For example, it can be 2 L / h, 2.2 L / h, 2.5 L / h, 2.8 L / h, or 3 L / h. However, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0033] Preferably, the complexing agent solution is an ammonia water solution with a mass concentration of 10% to 20%. For example, it can be 10%, 12%, 15%, 16%, 18%, or 20%. However, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0034] The present invention does not limit the flow rate of the complexing agent solution. As long as the ammonia concentration in the system is 4 g / L to 8 g / L during the coprecipitation reaction.

[0035] Preferably, the temperature range of the bottom liquid is 40°C to 60°C. For example, it can be 40°C, 45°C, 50°C, 55°C, or 60°C. However, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0036] Preferably, the pH value range of the bottom liquid is 11 to 12. For example, it can be 11, 11.2, 11.5, 11.8, or 12. However, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0037] The pH value of the bottom liquid in the present invention is adjusted by sodium hydroxide. The present invention does not limit the specific concentration of sodium hydroxide here. As long as the pH value of the bottom liquid satisfies the numerical range of 11 to 12.

[0038] Preferably, the ammonia concentration in the bottom liquid is 4 g / L to 8 g / L. For example, it can be 4 g / L, 5 g / L, 6 g / L, 7 g / L, or 8 g / L. However, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0039] The ammonia concentration of the bottom liquid in the present invention is calculated based on NH3 in the bottom liquid.

[0040] Preferably, the coprecipitation reaction proceeds until the particle size D 50 is 1.25 μm to 1.35 μm. Before that, the oxygen content in the reaction system is 0 vol%. Then, oxygen-containing gas is introduced at least twice until the particle size D 50 is 2.5 μm to 3.5 μm, and the feeding is stopped, and the coprecipitation continues until the reaction is complete.

[0041] As a preferred technical solution, in order to obtain a cathode material precursor with high sphericity and high tap density, the present invention conducts the coprecipitation reaction until the particle size D 50Before the particle size D is between 1.25 μm and 1.35 μm, the oxygen content in the reaction system is 0 vol%. 50 The particle size D is between 1.25 μm and 1.35 μm, and can be, for example, 1.25 μm, 1.26 μm, 1.28 μm, 1.3 μm, 1.32 μm or 1.35 μm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0042] Exemplarily, first perform nitrogen replacement to make the oxygen content in the reaction kettle 0 vol%, and then under stirring and nitrogen atmosphere conditions, add the nickel-cobalt-manganese ternary mixed salt solution, precipitant solution and complexing agent solution into the bottom liquid of the reaction kettle in parallel flow, and perform co-precipitation reaction until the particle size D 50 When it is between 1.25 μm and 1.35 μm, then under stirring and the first oxygen-containing atmosphere conditions, add the nickel-cobalt-manganese ternary mixed salt solution, precipitant solution and complexing agent solution into the bottom liquid of the reaction kettle in parallel flow, and perform co-precipitation reaction until the particle size D 50 When it is between 2.3 μm and 2.5 μm, continue the co-precipitation reaction under the second oxygen-containing atmosphere conditions until the particle size D 50 Is between 3.0 μm and 3.5 μm, stop feeding, and continue co-precipitation until the reaction is complete.

[0043] The first oxygen-containing atmosphere conditions are formed by continuously introducing a first oxygen-containing gas. The first oxygen-containing gas is composed of nitrogen and air, and the volume fraction of oxygen in the first oxygen-containing gas is 2 vol% to 6 vol%, and can be, for example, 2 vol%, 3 vol%, 4 vol%, 5 vol% or 6 vol%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0044] The second oxygen-containing atmosphere is formed by continuously introducing a second oxygen-containing gas. The second oxygen-containing gas is composed of nitrogen and air, and the volume fraction of oxygen in the second oxygen-containing gas is 3 vol% to 6 vol%, and can be, for example, 3 vol%, 4 vol%, 5 vol% or 6 vol%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0045] Preferably, a high-efficiency thickener is used during the co-precipitation reaction.

[0046] As a preferred technical solution of the preparation method described in the first aspect of the present invention, the preparation method includes the following steps:

[0047] First, perform nitrogen replacement, and then under stirring and oxygen-containing atmosphere conditions, add the nickel-cobalt-manganese ternary mixed salt solution, precipitant solution and complexing agent solution into the bottom liquid of the reaction kettle in parallel flow, and perform co-precipitation reaction until the particle size D 50 When it is between 2.5 μm and 3.5 μm, stop feeding, and continue co-precipitation until the reaction is complete to obtain the high-sphericity cathode material precursor.

[0048] During the coprecipitation reaction until the particle size D 50 When it is 2.5 μm to 3.5 μm, a high-efficiency thickener is used, and the collected particles are returned to the reaction kettle for continuous growth;

[0049] The oxygen-containing atmosphere is formed by continuously introducing an oxygen-containing gas. The oxygen-containing gas is composed of nitrogen and air, and the volume fraction range of oxygen in the oxygen-containing gas is 1 vol% to 20 vol%;

[0050] The temperature range of the bottom liquid is 40°C to 60°C, the pH value range is 11 to 12, and the ammonia concentration is 4 g / L to 8 g / L;

[0051] During the coprecipitation reaction, the pH value is maintained in the range of 10 to 12, the temperature range is 40°C to 60°C, and the ammonia concentration of the system is 4 g / L to 8 g / L;

[0052] The rotation speed of the stirring is 200 r / min to 400 r / min;

[0053] The concentration of the nickel-cobalt-manganese ternary mixed salt solution is 80 g / L to 120 g / L, and the flow rate is 6 L / h to 10 L / h;

[0054] The precipitant solution is a sodium hydroxide solution with a mass concentration of 28% to 32%, and the flow rate is 2 L / h to 3 L / h;

[0055] The complexing agent solution is an ammonia water solution with a mass concentration of 10% to 20%.

[0056] In the second aspect, the present invention provides a high-sphericity cathode material precursor, and the high-sphericity cathode material precursor is obtained by the preparation method described in the first aspect;

[0057] The sphericity of the high-sphericity cathode material precursor is ≥99%.

[0058] In the third aspect, the present invention provides an application of the high-sphericity cathode material precursor described in the second aspect, and the high-sphericity cathode material precursor is used for preparing a cathode material.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] By preparing the precursor under an oxygen-containing atmosphere, the precursor has a high sphericity and a relatively high tap density. The cathode material prepared from this precursor has good cycle stability and rate performance. Description of the Drawings

[0061] Figure 1 SEM image of the high-sphericity cathode material precursor prepared in Example 1;

[0062] Figure 2 SEM image of the high-sphericity cathode material precursor prepared in Example 2;

[0063] Figure 3 SEM image of the high-sphericity cathode material precursor prepared in Example 3;

[0064] Figure 4 SEM image of the high-sphericity cathode material precursor prepared in Example 4;

[0065] Figure 5 SEM image of the high-sphericity cathode material precursor prepared in Example 5;

[0066] Figure 6 SEM image of the high-sphericity cathode material precursor prepared in Example 6;

[0067] Figure 7 SEM image of the high-sphericity cathode material precursor prepared in Example 7;

[0068] Figure 8 SEM image of the cathode material precursor prepared in Comparative Example 1;

[0069] Figure 9 SEM image of the cathode material precursor prepared in Comparative Example 2;

[0070] Figure 10 SEM image of the cathode material precursor prepared in Comparative Example 3. Detailed implementation manners

[0071] The technical solution of the present invention will be further described below through specific implementation manners. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0072] For clearly illustrating the technical solution of the present invention, the cathode material in the specific implementation manners takes nickel-cobalt-manganese NCM622 as an example, and NCM622 is not regarded as a specific limitation on the technical solution of the present invention.

[0073] Example 1

[0074] This example provides a preparation method of a high-sphericity cathode material precursor, and the preparation method includes the following steps:

[0075] First, nitrogen is introduced for 3 hours for nitrogen replacement to make the oxygen content in the reaction kettle 0 vol%, and then under the conditions of stirring and an oxygen-containing atmosphere, a nickel-cobalt-manganese ternary mixed salt solution, a precipitant solution, and a complexing agent solution are added in parallel to the bottom liquid of the reaction kettle, and co-precipitation reaction is carried out until the particle size D50 When it reaches 3.2 μm, stop feeding and continue the coprecipitation until the reaction is complete to obtain the high-sphericity cathode material precursor;

[0076] During the coprecipitation reaction until the particle size D 50 When it reaches 3.2 μm, use a high-efficiency thickener, and the collected particles are returned to the reaction kettle for continuous growth;

[0077] The oxygen-containing atmosphere is formed by continuously introducing an oxygen-containing gas. The oxygen-containing gas is composed of nitrogen and air, and the volume fraction of oxygen in the oxygen-containing gas is 10 vol%;

[0078] The temperature range of the bottom liquid is 50 °C, the pH value range is 11.5, and the ammonia concentration is 6 g / L;

[0079] During the coprecipitation reaction, maintain the pH value range at 11, the temperature range at 50 °C, and the ammonia concentration of the system at 6 g / L;

[0080] The rotation speed of the stirring is 300 r / min;

[0081] The concentration of the nickel-cobalt-manganese ternary mixed salt solution is 100 g / L, and the flow rate is 8 L / h; the nickel salt in the nickel-cobalt-manganese ternary mixed salt solution is nickel chloride, the cobalt salt is cobalt chloride, and the manganese salt is manganese chloride;

[0082] The precipitant solution is a sodium hydroxide solution with a mass concentration of 30%, and the flow rate is 2.5 L / h;

[0083] The complexing agent solution is an ammonia water solution with a mass concentration of 15%.

[0084] The SEM image of the high-sphericity cathode material precursor obtained in this example is as Figure 1 shown.

[0085] Example 2

[0086] This example provides a preparation method of a high-sphericity cathode material precursor, and the preparation method includes the following steps:

[0087] First, introduce nitrogen for 3 hours for nitrogen replacement to make the oxygen content in the reaction kettle 0 vol%. Then, under the conditions of stirring and an oxygen-containing atmosphere, a nickel-cobalt-manganese ternary mixed salt solution, a precipitant solution, and a complexing agent solution are added in parallel to the bottom liquid of the reaction kettle, and the coprecipitation reaction is carried out until the particle size D 50 When it reaches 3.2 μm, stop feeding and continue the coprecipitation until the reaction is complete to obtain the high-sphericity cathode material precursor;

[0088] During the coprecipitation reaction until the particle size D 50 When it reaches 3.2 μm, use a high-efficiency thickener, and the collected particles are returned to the reaction kettle for continuous growth;

[0089] The oxygen-containing atmosphere is formed by continuously introducing an oxygen-containing gas, and the oxygen-containing gas is composed of nitrogen and air, and the volume fraction of oxygen in the oxygen-containing gas is 4 vol%;

[0090] The temperature range of the bottom liquid is 40 °C, the pH value range is 11, and the ammonia concentration is 8 g / L;

[0091] During the coprecipitation reaction, the pH value is maintained in the range of 10, the temperature range is 40 °C, and the ammonia concentration of the system is 8 g / L;

[0092] The rotation speed of the stirring is 200 r / min;

[0093] The concentration of the nickel cobalt manganese ternary mixed salt solution is 80 g / L, and the flow rate is 6 L / h; the nickel salt in the nickel cobalt manganese ternary mixed salt solution is nickel nitrate, the cobalt salt is cobalt nitrate, and the manganese salt is manganese nitrate;

[0094] The precipitant solution is a sodium hydroxide solution with a mass concentration of 28%, and the flow rate is 2 L / h;

[0095] The complexing agent solution is an ammonia water solution with a mass concentration of 10%.

[0096] The SEM image of the high-sphericity cathode material precursor obtained in this example is as Figure 2 shown.

[0097] Example 3

[0098] This example provides a method for preparing a high-sphericity cathode material precursor, and the preparation method includes the following steps:

[0099] First, nitrogen is introduced for 3 hours for nitrogen replacement to make the oxygen content in the reaction kettle 0 vol%, and then under the conditions of stirring and an oxygen-containing atmosphere, a nickel cobalt manganese ternary mixed salt solution, a precipitant solution, and a complexing agent solution are added in parallel to the bottom liquid of the reaction kettle, and coprecipitation reaction is carried out until the particle size D 50 reaches 3.2 μm, then the feeding is stopped, and coprecipitation is continued until the reaction is complete to obtain the high-sphericity cathode material precursor;

[0100] During the coprecipitation reaction until the particle size D 50 reaches 3.2 μm, a high-efficiency thickener is used, and the collected particles are returned to the reaction kettle for continuous growth;

[0101] The oxygen-containing atmosphere is formed by continuously introducing an oxygen-containing gas, and the oxygen-containing gas is composed of nitrogen and air, and the volume fraction of oxygen in the oxygen-containing gas is 20 vol%;

[0102] The temperature range of the bottom liquid is 60 °C, the pH value range is 12, and the ammonia concentration is 4 g / L;

[0103] During the coprecipitation reaction, the pH value is maintained in the range of 12, the temperature is in the range of 60 °C, and the ammonia concentration in the system is 4 g / L;

[0104] The rotation speed of the stirring is 400 r / min;

[0105] The concentration of the nickel-cobalt-manganese ternary mixed salt solution is 120 g / L, and the flow rate is 10 L / h; the nickel salt in the nickel-cobalt-manganese ternary mixed salt solution is nickel chloride, the cobalt salt is cobalt nitrate, and the manganese salt is manganese chloride;

[0106] The precipitant solution is a sodium hydroxide solution with a mass concentration of 32%, and the flow rate is 3 L / h;

[0107] The complexing agent solution is an ammonia water solution with a mass concentration of 20%.

[0108] The SEM image of the high-sphericity cathode material precursor obtained in this example is as Figure 3 shown.

[0109] Example 4

[0110] This example provides a method for preparing a high-sphericity cathode material precursor. Except that the initial atmosphere in the reaction kettle is an air atmosphere and nitrogen replacement is not carried out, the rest are the same as in Example 1.

[0111] The SEM image of the high-sphericity cathode material precursor obtained in this example is as Figure 4 shown.

[0112] Example 5

[0113] This example provides a method for preparing a high-sphericity cathode material precursor. Except that the timing of introducing the oxygen-containing gas is different from that in Example 1, the rest are the same as in Example 1. In this example:

[0114] First, nitrogen is introduced for 3 hours for nitrogen replacement to make the oxygen content in the reaction kettle 0 vol%, and then under the conditions of stirring and nitrogen atmosphere, the nickel-cobalt-manganese ternary mixed salt solution, the precipitant solution and the complexing agent solution are added in parallel to the bottom liquid of the reaction kettle, and coprecipitation reaction is carried out until the particle size D 50 reaches 1.3 μm, and then the oxygen-containing gas is introduced; the coprecipitation reaction is continued until the particle size D 50 reaches 3.2 μm, then the feeding is stopped, and the coprecipitation is continued until the reaction is complete;

[0115] The oxygen-containing gas is composed of nitrogen and air, and the volume fraction of oxygen in the oxygen-containing gas is 5 vol%.

[0116] The SEM image of the high-sphericity cathode material precursor obtained in this example is as Figure 5 shown.

[0117] Example 6

[0118] This example provides a method for preparing a high sphericity cathode material precursor. Except that the timing of introducing the oxygen-containing gas is different from that in Example 1, the rest are the same as in Example 1. In this example:

[0119] First, nitrogen is introduced for 3 hours for nitrogen replacement to make the oxygen content in the reaction kettle 0 vol%. Then, under stirring and nitrogen atmosphere conditions, a nickel-cobalt-manganese ternary mixed salt solution, a precipitant solution, and a complexing agent solution are added in parallel flow to the bottom liquid of the reaction kettle, and co-precipitation reaction is carried out until the particle size D 50 reaches 1.3 μm. Then, under stirring and the first oxygen-containing atmosphere conditions, a nickel-cobalt-manganese ternary mixed salt solution, a precipitant solution, and a complexing agent solution are added in parallel flow to the bottom liquid of the reaction kettle, and co-precipitation reaction is carried out until the particle size D 50 reaches 2.4 μm. Under the second oxygen-containing atmosphere conditions, the co-precipitation reaction is continued until the particle size D 50 reaches 3.2 μm, the feeding is stopped, and the co-precipitation is continued until the reaction is complete;

[0120] The first oxygen-containing atmosphere is formed by continuously introducing a first oxygen-containing gas. The first oxygen-containing gas is composed of nitrogen and air, and the volume fraction of oxygen in the first oxygen-containing gas is 2 vol%;

[0121] The second oxygen-containing atmosphere is formed by continuously introducing a second oxygen-containing gas. The second oxygen-containing gas is composed of nitrogen and air, and the volume fraction of oxygen in the second oxygen-containing gas is 6 vol%.

[0122] The SEM image of the high sphericity cathode material precursor obtained in this example is as Figure 6 shown.

[0123] Example 7

[0124] This example provides a method for preparing a high sphericity cathode material precursor. Except that the timing of introducing the oxygen-containing gas is different from that in Example 1, the rest are the same as in Example 1. In this example:

[0125] First, nitrogen is introduced for 3 hours for nitrogen replacement to make the oxygen content in the reaction kettle 0 vol%. Then, under stirring and nitrogen atmosphere conditions, a nickel-cobalt-manganese ternary mixed salt solution, a precipitant solution, and a complexing agent solution are added in parallel flow to the bottom liquid of the reaction kettle, and co-precipitation reaction is carried out until the particle size D 50 reaches 1.3 μm. Then, under stirring and the first oxygen-containing atmosphere conditions, a nickel-cobalt-manganese ternary mixed salt solution, a precipitant solution, and a complexing agent solution are added in parallel flow to the bottom liquid of the reaction kettle, and co-precipitation reaction is carried out until the particle size D 50 reaches 2.4 μm. Under the second oxygen-containing atmosphere conditions, the co-precipitation reaction is continued until the particle size D 50It is 3.2 μm, stop feeding, and continue co-precipitation until the reaction is complete;

[0126] The first oxygen-containing atmosphere is formed by continuously introducing a first oxygen-containing gas, and the first oxygen-containing gas is composed of nitrogen and air, and the volume fraction of oxygen in the first oxygen-containing gas is 6 vol%;

[0127] The second oxygen-containing atmosphere is formed by continuously introducing a second oxygen-containing gas, and the second oxygen-containing gas is composed of nitrogen and air, and the volume fraction of oxygen in the second oxygen-containing gas is 3 vol%.

[0128] The SEM image of the high-sphericity cathode material precursor obtained in this example is as Figure 7 shown.

[0129] Comparative Example 1

[0130] This comparative example provides a method for preparing a cathode material precursor. Except that the oxygen-containing gas is composed of nitrogen and air, and the volume fraction of oxygen in the oxygen-containing gas is 0.5 vol%, the rest are the same as in Example 1.

[0131] The SEM image of the cathode material precursor obtained in this comparative example is as Figure 8 shown.

[0132] Comparative Example 2

[0133] This comparative example provides a method for preparing a cathode material precursor. Except that the oxygen-containing gas is composed of nitrogen and oxygen, and the volume fraction of oxygen in the oxygen-containing gas is 22 vol%, the rest are the same as in Example 1.

[0134] The SEM image of the cathode material precursor obtained in this comparative example is as Figure 9 shown.

[0135] Comparative Example 3

[0136] This comparative example provides a method for preparing a cathode material precursor. Except that the co-precipitation reaction is carried out in a nitrogen atmosphere, that is, the volume fraction of oxygen is 0 vol%, the rest are the same as in Example 1.

[0137] The SEM image of the cathode material precursor obtained in this comparative example is as Figure 10 shown.

[0138] Performance Characterization

[0139] I) Sphericity Test

[0140] The sphericity and tap density of the high-sphericity cathode material precursors obtained in Examples 1-7 and the cathode material precursors obtained in Comparative Examples 1-3 were tested. The tap density was tested using a GeoPyc-136 tap density meter, and the results are shown in Table 1.

[0141] The SEM image of the high-sphericity cathode material precursor obtained in Example 1 is as Figure 1 shown, and the SEM image of the cathode material precursor obtained in Comparative Example 3 is as Figure 2 shown. From Figure 1 the comparison between Figure 2 and it can be seen that by preparing the precursor under micro-oxidation conditions, the present invention endows it with excellent sphericity, thereby improving its tap density.

[0142] Table 1

[0143] Sphericity <![CDATA[Tap density (g / cm 3 )]]> Example 1 88％ 1.61 Example 2 90％ 1.80 Example 3 82％ 1.47 Example 4 80％ 1.53 Example 5 96％ 1.85 Example 6 96％ 1.87 Example 7 99％ 1.91 Comparative Example 1 50％ 1.67 Comparative Example 2 80％ 1.45 Comparative Example 3 10％ 1.55

[0144] The high-sphericity cathode material precursors provided in Examples 1-7, the cathode precursors provided in Comparative Examples 1-3, and lithium hydroxide were uniformly mixed in a mortar at a ratio of 1:1.05, and calcined at 850 °C for 20 h to obtain a cathode material. The cathode material was prepared into a cathode electrode sheet, and a coin cell was prepared using a lithium sheet as the counter electrode. The cycle performance and rate performance of the obtained coin cell were tested.

[0145] A battery performance test system (model: BTS05 / 10C8D-HP) of Shenghong Electric Co., Ltd. was used to conduct a 600-cycle capacity retention rate test: at 25 °C, cycling was carried out with a charge-discharge regime of 0.5C. After 600 cycles, the discharge capacity of the battery at this time was divided by the discharge capacity of the first cycle, which was the 600-cycle capacity retention rate of the battery;

[0146] Rate performance test: at 25 °C, cycling was carried out 10 times with charge-discharge regimes of 0.1C, 0.5C, 1C, and 3C. The discharge capacity of the battery at this time was divided by the discharge capacity of the first cycle, and the rate performance of the material could be obtained by comparison

[0147] Table 2

[0148]

[0149]

[0150] In summary, by preparing the precursor in an oxygen-containing atmosphere, the present invention endows the precursor with high sphericity and a relatively high tap density. The cathode material prepared from this precursor has good cycle stability and rate performance.

[0151] The above are only the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for preparing a cathode material precursor with high sphericity, characterized in that, The preparation method includes the following steps: Under an oxygen-containing atmosphere condition, a nickel-cobalt-manganese ternary mixed salt solution, a precipitant solution, a complexing agent solution, and a bottom liquid are mixed to carry out a coprecipitation reaction. The coprecipitation reaction is carried out until the particle size D 50 is before 1.25 μm to 1.35 μm, and the oxygen content in the reaction system is 0 vol%; then, under the conditions of stirring and a first oxygen-containing atmosphere with an oxygen volume fraction of 5 vol% to 6 vol%, the nickel-cobalt-manganese ternary mixed salt solution, the precipitant solution, and the complexing agent solution are added in parallel flow to the bottom liquid of the reaction kettle, and the coprecipitation reaction is carried out until the particle size D50 is 2.3 μm to 2.5 μm. Under the conditions of a second oxygen-containing atmosphere with an oxygen volume fraction of 3 vol% to 4 vol%, the coprecipitation reaction is continued until the particle size D50 is 3.0 μm to 3.5 μm, the feeding is stopped, and the coprecipitation is continued until the reaction is complete to obtain the high-sphericity cathode material precursor; During the coprecipitation reaction, the ammonia concentration in the system is 4 g / L to 8 g / L.

2. The preparation method according to claim 1, characterized in that, During the coprecipitation reaction, the pH value is maintained in the range of 10 to 12.

3. The preparation method according to claim 1, characterized in that, During the coprecipitation reaction, the temperature range is 40°C to 60°C.

4. The preparation method according to claim 1, characterized in that, During the coprecipitation reaction, stirring is carried out, and the rotation speed of the stirring is 200 r / min to 400 r / min.

5. The preparation method according to claim 1, wherein The concentration of the nickel-cobalt-manganese ternary mixed salt solution is 80 g / L to 120 g / L.

6. The preparation method according to claim 1, characterized in that, During the mixing, the flow rate of the nickel-cobalt-manganese ternary mixed salt solution is 6 L / h to 10 L / h.

7. The preparation method according to claim 1, characterized in that, The precipitant solution is a sodium hydroxide solution with a mass concentration of 28% to 32%.

8. The preparation method according to claim 1, wherein During the mixing, the flow rate of the precipitant solution is 2 L / h to 3 L / h.

9. The preparation method according to claim 1, characterized in that, The complexing agent solution is an ammonia water solution with a mass concentration of 10% to 20%.

10. The preparation method according to claim 1, characterized in that, The temperature range of the bottom liquid is 40°C to 60°C.

11. The preparation method according to claim 1, characterized in that, The pH value range of the bottom liquid is 11 to 12.

12. The preparation method according to claim 1, wherein The ammonia concentration in the bottom liquid is 4 g / L to 8 g / L.

13. The preparation method according to claim 1, characterized in that, A high-efficiency thickener is used during the coprecipitation reaction.

14. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: First, nitrogen replacement is carried out. Then, under stirring and an oxygen-containing atmosphere condition, the nickel-cobalt-manganese ternary mixed salt solution, the precipitant solution, and the complexing agent solution are added in parallel flow to the bottom liquid in the reaction kettle. Then, under stirring and a first oxygen-containing atmosphere condition with an oxygen volume fraction of 5 vol% to 6 vol%, the nickel-cobalt-manganese ternary mixed salt solution, the precipitant solution, and the complexing agent solution are added in parallel flow to the bottom liquid in the reaction kettle. The coprecipitation reaction is carried out until the particle size D50 is 2.3 μm to 2.5 μm. Under a second oxygen-containing atmosphere condition with an oxygen volume fraction of 3 vol% to 4 vol%, the coprecipitation reaction is continued until the particle size D50 is 3.0 μm to 3.5 μm. The feeding is stopped, and the coprecipitation is continued until the reaction is complete to obtain the high-sphericity cathode material precursor; Coprecipitation reaction to a particle size D 50 During the process where the particle size is 2.5 μm to 3.5 μm, a high-efficiency thickener is used, and the collected particles are returned to the reaction kettle for continuous growth; The temperature range of the bottom liquid is 40°C to 60°C, the pH value range is 11 to 12, and the ammonia concentration is 4 g / L to 8 g / L; During the coprecipitation reaction, the pH value is maintained in the range of 10 to 12, the temperature range is 40°C to 60°C, and the ammonia concentration in the system is 4 g / L to 8 g / L; The rotation speed of the stirring is 200 r / min to 400 r / min; The concentration of the nickel-cobalt-manganese ternary mixed salt solution is 80 g / L to 120 g / L, and the flow rate is 6 L / h to 10 L / h; The precipitant solution is a sodium hydroxide solution with a mass concentration of 28% to 32%, and the flow rate is 2 L / h to 3 L / h; The complexing agent solution is an ammonia water solution with a mass concentration of 10% to 20%.

15. A high sphericity cathode material precursor, characterized in that, The high-sphericity cathode material precursor is obtained by the preparation method according to any one of claims 1 to 14; The sphericity of the high-sphericity cathode material precursor is ≥99%; 16. An application of the high-sphericity cathode material precursor as described in claim 15, characterized in that, The high-sphericity cathode material precursor is used for preparing a cathode material.

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