Production device and production method of core-shell precursor with normal particle size distribution

Abstract

The invention provides a production device and a production method of a core-shell precursor with normal particle size distribution, the production device comprises a homogeneous reactor, a stirring reactor and a thickener which are sequentially connected through a pipeline, and the thickener is connected back to the stirring reactor through a pipeline to form a material circulation loop; the production device adopts a continuous method to produce the core-shell precursor with normal particle size distribution. According to the method, a homogeneous reactor and a stirring reactor are adopted to synchronously carry out coprecipitation reaction, and a thickener is adopted to realize continuous reaction and particle size control, so that a core-shell precursor with normal particle size distribution is obtained. The problem of heat instability of a high-nickel positive electrode material in the prior art is solved, meanwhile, the production efficiency and quality of the core-shell precursor are improved, the performance and safety of the battery are finally improved, and large-scale popularization and application are facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery manufacturing, and relates to a method for producing a core-shell precursor, and in particular to a production device and a production method for a core-shell precursor with a normally distributed particle size. Background Art

[0002] As the current demand for electric vehicle mileage continues to increase, the requirements for lithium-ion batteries for long driving range are gradually increasing. High-nickel cathodes have become a current research hotspot due to their excellent performance such as high energy density and high rate, but the thermal instability of high-nickel cathodes leads to frequent battery spontaneous combustion incidents, so the development of high-nickel core-shell precursors is imperative.

[0003] In order to improve the compaction density of existing core-shell positive electrode materials, large-particle core-shell precursors and small-particle core-shell precursors need to be prepared separately in the precursor stage, and then mixed and used after sintering, which has the problem of low efficiency.

[0004] In addition, in order to improve the mass production success rate of the precursor stage in the production stage, the above method needs to control the reaction time within 100 hours. Therefore, it is necessary to reduce the number of seed crystals by quickly lowering the pH in the early stage of the reaction. However, this will cause serious agglomeration of the seed crystals, thereby reducing the compaction density of the positive electrode material, and irregular particles are more likely to crack, which in turn leads to a significant reduction in the battery cycle performance.

[0005] It can be seen that how to provide a method for producing a core-shell precursor to solve the thermal instability problem of high-nickel positive electrode materials in the prior art, while improving the production efficiency and quality of the core-shell precursor, and ultimately achieving improved battery performance and safety, has become an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a production device and a production method for a core-shell precursor with a normally distributed particle size, which solves the thermal instability problem of high-nickel positive electrode materials in the prior art, while improving the production efficiency and quality of the core-shell precursor, ultimately achieving an improvement in battery performance and safety, which is conducive to large-scale promotion and application.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a production device for a core-shell precursor with a normally distributed particle size, the production device comprising a homogenizing reactor, a stirring reactor and a concentrator connected in sequence by pipelines, and the concentrator is connected back to the stirring reactor by a pipeline to form a material circulation loop.

[0009] The production device adopts a continuous method to produce a core-shell precursor with a normally distributed particle size.

[0010] The production device provided by the present invention realizes the continuous production of core-shell precursors by sequentially connecting a homogenizing reactor, a stirring reactor and a concentrator, and the particle size of the obtained core-shell precursor is normally distributed, which reduces the mixed batch process of positive electrode materials and greatly improves the production efficiency of the precursor. The production device can not only prepare high-nickel core-shells, but also prepare lithium-rich manganese-based core-shells, and has broad application prospects.

[0011] Preferably, the homogenizing reactor and / or the stirred reactor is provided with an online particle size monitor for online monitoring of the particle size range of the seed crystals in the homogenizing reactor and the particle size distribution state of the seed crystals in the stirred reactor.

[0012] In the present invention, the number of the online particle size monitor may be one or more. When the number of the online particle size monitor is one, the homogenizing reactor and the stirring reactor are connected in parallel to the same online particle size monitor.

[0013] Preferably, the homogenizing reactor and / or the stirring reactor is provided with an online pH monitor for online monitoring of the pH value of the mixed solution in the reactor.

[0014] In a second aspect, the present invention provides a method for producing a core-shell precursor with a normally distributed particle size using the production device as described in the first aspect, wherein the method uses a homogenizing reactor and a stirring reactor to simultaneously carry out a co-precipitation reaction, and uses a concentrator to achieve continuous reaction and particle size control, thereby obtaining a core-shell precursor with a normally distributed particle size.

[0015] The production method provided by the present invention obtains precursor particles with high sphericity through the coordinated cooperation between a homogenizing reactor, a stirring reactor and a concentrator. Because the force is more balanced, the compaction density of the positive electrode material and the energy density of the battery are improved. The obtained positive electrode material with high sphericity reduces the risk of cracks during the battery cycle, and significantly improves the cycle performance of the battery.

[0016] In addition, for high-nickel core-shell materials, high sphericity can significantly improve the thermal stability of ternary lithium batteries, thereby improving the safety and service life of the batteries.

[0017] Preferably, the method comprises the following steps:

[0018] (1) mixing nickel salt, cobalt salt, manganese salt and pure water according to a molar ratio of Ni:Co:Mn=x1:y1:z1 to obtain a first salt solution;

[0019] (2) mixing nickel salt, cobalt salt, manganese salt and pure water according to a molar ratio of Ni:Co:Mn=x2:y2:z2 to obtain a second salt solution;

[0020] (3) injecting the first salt solution, the precipitant solution and the complexing agent solution into a homogenizing reactor to carry out a first coprecipitation reaction, controlling the particle size of the seed crystal core by adjusting the residence time, and continuously injecting into the stirring reactor;

[0021] (4) injecting the second salt solution, the precipitant solution and the complexing agent solution into the stirred reactor for a second coprecipitation reaction, starting the thickener when the liquid level reaches the thickening level, continuing the reaction until the particle size reaches the target requirement, and suspending the homogenizing reactor and the stirred reactor;

[0022] (5) collecting the materials in the homogenizing reactor and the stirring reactor, and obtaining a core-shell precursor with a normally distributed particle size after solid-liquid separation.

[0023] Preferably, the molar ratio of step (1) satisfies: x1+y1+z1=1, and 0.8<x1<0.99, for example, x1=0.81, 0.82, 0.84, 0.86, 0.88, 0.9, 0.92, 0.94, 0.96 or 0.98, 0.01≤y1<0.1, for example, y1=0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08 or 0.09, 0.01<z1<0.1, for example, z1=0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08 or 0.09, but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0024] Preferably, the molar ratio of step (2) satisfies: x2+y2+z2=1, and 0.5<x2<0.8, for example, x2=0.51, 0.55, 0.6, 0.65, 0.7, 0.75 or 0.79, 0.01≤y2<0.4, for example, y2=0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35 or 0.39, 0 .05<z2<0.25, for example, z2=0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23 or 0.24, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] Preferably, the nickel salt, cobalt salt and manganese salt in step (1) and step (2) are any one of sulfate, nitrate or chloride salts of the corresponding metal 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.

[0026] Preferably, the total metal ion concentration of the first salt solution in step (1) and the second salt solution in step (2) is respectively 1.6-2.4 mol / L, for example, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L or 2.4 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] Preferably, the precipitant solutions in step (3) and step (4) respectively include sodium hydroxide solutions.

[0028] Preferably, the concentration of the precipitant solution in step (3) and step (4) is 9-12 mol / L, for example, 9 mol / L, 9.5 mol / L, 10 mol / L, 10.5 mol / L, 11 mol / L, 11.5 mol / L or 12 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0029] Preferably, the complexing agent solutions in step (3) and step (4) respectively include aqueous ammonia.

[0030] Preferably, the concentration of the complexing agent solution in step (3) and step (4) is 8-10 mol / L, for example, 8 mol / L, 8.2 mol / L, 8.4 mol / L, 8.6 mol / L, 8.8 mol / L, 9 mol / L, 9.2 mol / L, 9.4 mol / L, 9.6 mol / L, 9.8 mol / L or 10 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] Preferably, during the first coprecipitation reaction in step (3), the injection rate of the first salt solution is 4-8 L / h, for example, 4 L / h, 4.5 L / h, 5 L / h, 5.5 L / h, 6 L / h, 6.5 L / h, 7 L / h, 7.5 L / h or 8 L / h, the injection rate of the precipitant solution is 2.2-2.6 L / h, for example, 2.2 L / h, 2.3 L / h, 2.4 L / h, 2.5 L / h or 2.6 L / h, and the injection rate of the complexing agent solution is 1-1.5 L / h, for example, 1 L / h, 1.1 L / h, 1.2 L / h, 1.3 L / h, 1.4 L / h or 1.5 L / h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] Preferably, the residence time in step (3) is 2-2.5 h, for example, 2 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h or 2.5 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] Preferably, in the second coprecipitation reaction process of step (4), the injection flow rate of the second salt solution is 4-8 L / h, for example, 4 L / h, 4.5 L / h, 5 L / h, 5.5 L / h, 6 L / h, 6.5 L / h, 7 L / h, 7.5 L / h or 8 L / h, the injection flow rate of the precipitant solution is 2.2-2.4 L / h, for example, 2.2 L / h, 2.3 L / h or 2.4 L / h, and the injection flow rate of the complexing agent solution is 0.6-1.2 L / h, for example, 0.6 L / h, 0. .7L / h, 0.8L / h, 0.9L / h, 1L / h, 1.1L / h or 1.2L / h, and maintain the pH of the mixed solution at 9-13, for example, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5 or 13, and the ammonia concentration is 3-6g / L, for example, 3g / L, 3.5g / L, 4g / L, 4.5g / L, 5g / L, 5.5g / L or 6g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0034] Preferably, the target requirement for the particle size in step (4) is D50 ≥ 8 μm, for example, it can be 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm or 12 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] Preferably, the temperatures of the first coprecipitation reaction in step (3) and the second coprecipitation reaction in step (4) are respectively 40-65°C, for example, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C or 65°C, but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] Preferably, the first coprecipitation reaction in step (3) and the second coprecipitation reaction in step (4) are respectively carried out in an atmosphere of a protective gas, and the protective gas comprises nitrogen.

[0037] Preferably, the solid-liquid separation in step (5) includes centrifugation, washing and drying.

[0038] Preferably, the solid-liquid separation in step (5) further includes removing magnetic foreign matter.

[0039] As a preferred technical solution of the second aspect of the present invention, the method adopts a homogenizing reactor and a stirring reactor to simultaneously carry out a coprecipitation reaction, and adopts a thickener to achieve continuous reaction and particle size control, to obtain a core-shell precursor with a normally distributed particle size, specifically comprising the following steps:

[0040] (1) mixing nickel salt, cobalt salt, manganese salt and pure water according to the molar ratio of Ni:Co:Mn=x1:y1:z1 to obtain a first salt solution with a total metal ion concentration of 1.6-2.4 mol / L; the molar ratio satisfies: x1+y1+z1=1, and 0.8<x1<0.99, 0.01≤y1<0.1, 0.01<z1<0.1;

[0041] (2) mixing nickel salt, cobalt salt, manganese salt and pure water according to the molar ratio of Ni:Co:Mn=x2:y2:z2 to obtain a second salt solution with a total metal ion concentration of 1.6-2.4 mol / L; the molar ratio satisfies: x2+y2+z2=1, and 0.5<x2<0.8, 0.01≤y2<0.4, 0.05<z2<0.25;

[0042] (3) injecting the first salt solution, the precipitant solution and the complexing agent solution into a homogenizing reactor, and controlling the injection flow rate of the first salt solution to 4-8 L / h, the injection flow rate of the precipitant solution to 2.2-2.6 L / h, and the injection flow rate of the complexing agent solution to 1-1.5 L / h, performing a first coprecipitation reaction at 40-65° C. in a nitrogen atmosphere, controlling the particle size of the seed core by adjusting the residence time to 2-2.5 h, and continuously injecting into the stirring reactor;

[0043] (4) injecting the second salt solution, the precipitant solution and the complexing agent solution into the stirred reactor, and controlling the injection flow rate of the second salt solution to 4-8 L / h, the injection flow rate of the precipitant solution to 2.2-2.4 L / h, and the injection flow rate of the complexing agent solution to 0.6-1.2 L / h, while maintaining the pH of the mixed solution at 9-13 and the ammonia concentration at 3-6 g / L, and conducting the second coprecipitation reaction at 40-65° C. in a nitrogen atmosphere, and starting the thickener when the liquid level reaches the thickening level, continuing the reaction until the particle size D50 is ≥8 μm, and suspending the homogenizing reactor and the stirred reactor;

[0044] (5) collecting the materials in the homogenizing reactor and the stirring reactor, and then centrifuging, washing and drying them to obtain a core-shell precursor with a normally distributed particle size after removing the magnetic foreign matter.

[0045] Wherein, the nickel salt, cobalt salt and manganese salt in step (1) and step (2) are any one or a combination of at least two of sulfate, nitrate or chloride salts of the corresponding metal ions; the precipitant solution in step (3) and step (4) respectively includes a sodium hydroxide solution with a concentration of 9-12 mol / L, and the complexing agent solution respectively includes ammonia water with a concentration of 8-10 mol / L.

[0046] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) The production device provided by the present invention realizes the continuous production of core-shell precursors by sequentially connecting a homogenizing reactor, a stirring reactor and a concentrator, and the particle size of the obtained core-shell precursor is normally distributed, which reduces the mixed batch process of the positive electrode material and greatly improves the production efficiency of the precursor. The production device can not only prepare high-nickel core-shell, but also prepare lithium-rich manganese-based core-shell, and has broad application prospects.

[0049] (2) The production method provided by the present invention produces high-sphericity precursor particles through the coordinated cooperation between a homogenizing reactor, a stirring reactor and a concentrator. Because the force is more balanced, the compaction density of the positive electrode material and the energy density of the battery are improved. The obtained high-sphericity positive electrode material reduces the risk of cracks during the battery cycle, significantly improving the battery cycle performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of the structure of a production device for a core-shell precursor with a normally distributed particle size provided by the present invention;

[0051] Figure 2 This is a transmission electron microscope photograph of the core-shell precursor obtained by the production method provided in Example 1.

[0052] Among them: 1-homogeneous reactor; 2-stirring reactor; 3-thickener. DETAILED DESCRIPTION

[0053] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0054] The present invention provides a production device for a core-shell precursor having a normally distributed particle size, such as Figure 1As shown, the production device includes a homogenizing reactor 1, a stirring reactor 2 and a concentrator 3 which are connected in sequence through pipelines, and the concentrator 3 is connected back to the stirring reactor 2 through a pipeline to form a material circulation loop; the production device adopts a continuous method to produce core-shell precursors with a normally distributed particle size.

[0055] In the present invention, the homogenizing reactor 1 is provided with an online particle size monitor, and the stirring reactor 2 is provided with an online pH monitor (not shown in the figure).

[0056] Example 1

[0057] This embodiment provides a method for producing a core-shell precursor with a normally distributed particle size using the above-mentioned production device. The method uses a homogenizing reactor 1 and a stirring reactor 2 to simultaneously perform a coprecipitation reaction, and uses a concentrator 3 to achieve continuous reaction and particle size control to obtain a core-shell precursor with a normally distributed particle size. The method specifically includes the following steps:

[0058] (1) mixing nickel sulfate, cobalt sulfate, manganese sulfate and pure water according to a molar ratio of Ni:Co:Mn=0.9:0.05:0.05 to obtain a first salt solution with a total metal ion concentration of 2 mol / L;

[0059] (2) mixing nickel sulfate, cobalt sulfate, manganese sulfate and pure water according to a molar ratio of Ni:Co:Mn=0.65:0.2:0.15 to obtain a second salt solution with a total metal ion concentration of 2 mol / L;

[0060] (3) injecting a first salt solution, a sodium hydroxide solution with a concentration of 10 mol / L, and an ammonia solution with a concentration of 10 mol / L into a homogenizing reactor 1, and controlling the injection flow rate of the first salt solution to 6 L / h, the injection flow rate of the sodium hydroxide solution to 2.3 L / h, and the injection flow rate of the ammonia solution to 1 L / h, and performing a first coprecipitation reaction at 52° C. in a nitrogen atmosphere, controlling the particle size of the seed core by adjusting the residence time to 2.17 h, and continuously injecting into the stirred reactor 2;

[0061] (4) injecting a second salt solution, a sodium hydroxide solution with a concentration of 10 mol / L, and an ammonia solution with a concentration of 10 mol / L into the stirred reactor 2, and controlling the injection flow rate of the second salt solution to 6 L / h, the injection flow rate of the sodium hydroxide solution to 1.95 L / h, and the injection flow rate of the ammonia solution to 1.0 L / h, while maintaining the pH of the mixed solution at 10±0.5 and the ammonia concentration at 4±0.5 g / L, and conducting a second coprecipitation reaction at 50° C. in a nitrogen atmosphere. When the liquid level reaches the dense liquid level, the thickener is opened, and the reaction is continued until the particle size D50 is ≥8 μm, and the homogenizing reactor 1 and the stirred reactor 2 are suspended;

[0062] (5) The materials in the homogenizing reactor 1 and the stirring reactor 2 are collected, and then centrifuged, washed and dried to obtain a core-shell precursor with a normally distributed particle size after removing the magnetic foreign matter.

[0063] Figure 2 TEM picture of the core-shell precursor obtained in this example.

[0064] Depend on Figure 2 It can be seen that the particle size of the core-shell precursor obtained in this embodiment is normally distributed, and the sphericity is significantly higher than that of the precursor obtained by the traditional preparation method.

[0065] Example 2

[0066] This embodiment provides a method for producing a core-shell precursor with a normally distributed particle size using the above-mentioned production device. The method uses a homogenizing reactor 1 and a stirring reactor 2 to simultaneously perform a coprecipitation reaction, and uses a concentrator 3 to achieve continuous reaction and particle size control to obtain a core-shell precursor with a normally distributed particle size. The method specifically includes the following steps:

[0067] (1) mixing nickel nitrate, cobalt nitrate, manganese nitrate and pure water in a molar ratio of Ni:Co:Mn=0.85:0.09:0.06 to obtain a first salt solution with a total metal ion concentration of 1.6 mol / L;

[0068] (2) mixing nickel nitrate, cobalt nitrate, manganese nitrate and pure water in a molar ratio of Ni:Co:Mn=0.6:0.2:0.2 to obtain a second salt solution with a total metal ion concentration of 1.6 mol / L;

[0069] (3) injecting a first salt solution, a sodium hydroxide solution with a concentration of 9 mol / L, and an ammonia solution with a concentration of 8 mol / L into the homogenizing reactor 1, and controlling the injection flow rate of the first salt solution to 8 L / h, the injection flow rate of the sodium hydroxide solution to 2.6 L / h, and the injection flow rate of the ammonia solution to 1.5 L / h, and performing a first coprecipitation reaction at 65° C. in a nitrogen atmosphere, controlling the particle size of the seed core by adjusting the residence time to 1.63 h, and continuously injecting into the stirred reactor 2;

[0070] (4) injecting a second salt solution, a sodium hydroxide solution with a concentration of 9 mol / L, and an ammonia solution with a concentration of 8 mol / L into the stirred reactor 2, and controlling the injection flow rate of the second salt solution to 8 L / h, the injection flow rate of the sodium hydroxide solution to 2.4 L / h, and the injection flow rate of the ammonia solution to 1.2 L / h, while maintaining the pH of the mixed solution at 10±1 and the ammonia concentration at 5±1 g / L, and conducting a second coprecipitation reaction at 60° C. in a nitrogen atmosphere. When the liquid level reaches the thickening level, the thickener 3 is opened, and the reaction is continued until the particle size D50 is ≥8 μm, and the homogenizing reactor 1 and the stirred reactor 2 are suspended;

[0071] (5) The materials in the homogenizing reactor 1 and the stirring reactor 2 are collected, and then centrifuged, washed and dried to obtain a core-shell precursor with a normally distributed particle size after removing the magnetic foreign matter.

[0072] The particle size distribution and sphericity of the core-shell precursor obtained in this example are similar to those in Example 1, so they are not described here in detail.

[0073] Example 3

[0074] This embodiment provides a method for producing a core-shell precursor with a normally distributed particle size using the above-mentioned production device. The method uses a homogenizing reactor 1 and a stirring reactor 2 to simultaneously perform a coprecipitation reaction, and uses a concentrator 3 to achieve continuous reaction and particle size control to obtain a core-shell precursor with a normally distributed particle size. The method specifically includes the following steps:

[0075] (1) mixing nickel chloride, cobalt chloride, manganese chloride and pure water according to a molar ratio of Ni:Co:Mn=0.95:0.01:0.04 to obtain a first salt solution with a total metal ion concentration of 2.4 mol / L;

[0076] (2) mixing nickel chloride, cobalt chloride, manganese chloride and pure water according to a molar ratio of Ni:Co:Mn=0.7:0.15:0.15 to obtain a second salt solution with a total metal ion concentration of 2.4 mol / L;

[0077] (3) injecting a first salt solution, a sodium hydroxide solution with a concentration of 12 mol / L, and an ammonia solution with a concentration of 10 mol / L into the homogenizing reactor 1, and controlling the injection flow rate of the first salt solution to 4 L / h, the injection flow rate of the sodium hydroxide solution to 1.1 L / h, and the injection flow rate of the ammonia solution to 1.2 L / h, and performing a first coprecipitation reaction at 45° C. in a nitrogen atmosphere, controlling the particle size of the seed crystal kernel by adjusting the residence time to 3.17 h, and continuously injecting into the stirred reactor 2;

[0078] (4) injecting a second salt solution, a sodium hydroxide solution with a concentration of 12 mol / L, and an ammonia solution with a concentration of 10 mol / L into the stirred reactor 2, and controlling the injection flow rate of the second salt solution to 4 L / h, the injection flow rate of the sodium hydroxide solution to 1.05 L / h, and the injection flow rate of the ammonia solution to 0.8 L / h, while maintaining the pH of the mixed solution at 10.5±0.7 and the ammonia concentration at 4±1 g / L, and conducting a second coprecipitation reaction at 45° C. in a nitrogen atmosphere. When the liquid level reaches the dense liquid level, the thickener 3 is opened, and the reaction is continued until the particle size D50 is ≥8 μm, and the homogenizing reactor 1 and the stirred reactor 2 are suspended;

[0079] (5) The materials in the homogenizing reactor 1 and the stirring reactor 2 are collected, and then centrifuged, washed and dried to obtain a core-shell precursor with a normally distributed particle size after removing the magnetic foreign matter.

[0080] The particle size distribution and sphericity of the core-shell precursor obtained in this example are similar to those in Example 1, so they are not described here in detail.

[0081] Performance Testing

[0082] The core-shell precursors obtained in Examples 1-3 were subjected to solid phase sintering to obtain corresponding positive electrode materials, and the obtained positive electrode materials were used to make battery pole pieces and button cells. The specific process is as follows:

[0083] (1) mixing lithium carbonate and the core-shell precursor uniformly and sintering them in stages, wherein the first stage is sintering at 400° C. for 4 h and the second stage is sintering at 800° C. for 8 h to obtain a positive electrode material;

[0084] (2) The positive electrode material, acetylene black and polyvinylidene fluoride were added to N-methyl-2-pyridine alkanone in a mass ratio of 8:1:1 to prepare a solution, which was then evenly applied on an aluminum foil, dried and punched into a thin sheet; the obtained battery electrode, elemental sodium sheet, glass fiber separator, electrolyte (NaClO4) gasket, shrapnel and battery shell were assembled into a button battery in an Ar gas glove box.

[0085] Table 1 below shows the electrochemical performance test data of button cells prepared using the core-shell precursors obtained in Examples 1-3.

[0086] Table 1

[0087]

[0088] It can be seen that the production device provided by the present invention realizes the continuous production of core-shell precursors through the homogenizing reactor, the stirring reactor and the concentrator connected in sequence, and the particle size of the obtained core-shell precursor is normally distributed, which reduces the mixed batch process of the positive electrode material and greatly improves the production efficiency of the precursor. The production device can not only prepare high-nickel core-shell, but also prepare lithium-rich manganese-based core-shell, and has broad application prospects.

[0089] In addition, the production method provided by the present invention obtains precursor particles with high sphericity through the coordinated cooperation between a homogenizing reactor, a stirring reactor and a concentrator. Because the force is more balanced, the compaction density of the positive electrode material and the energy density of the battery are improved. The obtained positive electrode material with high sphericity reduces the risk of cracks during the battery cycle, significantly improving the cycle performance of the battery.

[0090] The applicant declares that the above is only a specific implementation mode 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 shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A production device for a core-shell precursor with a normally distributed particle size, characterized in that: The production device comprises a homogenizing reactor, a stirring reactor and a thickener which are sequentially connected by pipelines, and the thickener is connected back to the stirring reactor by a pipeline to form a material circulation loop; The production device adopts a continuous method to produce a core-shell precursor with a normally distributed particle size.

2. The production device according to claim 1, characterized in that: The homogenizing reactor and / or the stirring reactor is provided with an online particle size monitor; Preferably, the homogenizing reactor and / or the stirred reactor is provided with an online pH monitor.

3. A method for producing a core-shell precursor with a normal particle size distribution using the production device as claimed in claim 1 or 2, characterized in that: The method adopts a homogenizing reactor and a stirring reactor to synchronously carry out a coprecipitation reaction, and adopts a concentrator to realize continuous reaction and particle size control, so as to obtain a core-shell precursor with a normally distributed particle size.

4. The method according to claim 3, characterized in that The method comprises the following steps: (1) mixing nickel salt, cobalt salt, manganese salt and pure water according to a molar ratio of Ni:Co:Mn=x1:y1:z1 to obtain a first salt solution; (2) mixing nickel salt, cobalt salt, manganese salt and pure water according to a molar ratio of Ni:Co:Mn=x2:y2:z2 to obtain a second salt solution; (3) injecting the first salt solution, the precipitant solution and the complexing agent solution into a homogenizing reactor to carry out a first coprecipitation reaction, controlling the particle size of the seed crystal core by adjusting the residence time, and continuously injecting into the stirring reactor; (4) injecting the second salt solution, the precipitant solution and the complexing agent solution into the stirred reactor for a second coprecipitation reaction, starting the thickener when the liquid level reaches the thickening level, continuing the reaction until the particle size reaches the target requirement, and suspending the homogenizing reactor and the stirred reactor; (5) collecting the materials in the homogenizing reactor and the stirring reactor, and obtaining a core-shell precursor with a normally distributed particle size after solid-liquid separation.

5. The method according to claim 4, characterized in that The molar ratio of step (1) satisfies: x1+y1+z1=1, and 0.8<x1<0.99, 0.01≤y1<0.1, 0.01<z1<0.1; Preferably, the molar ratio in step (2) satisfies: x2+y2+z2=1, and 0.5<x2<0.8, 0.01≤y2<0.4, 0.05<z2<0.

25.

6. The method according to claim 4 or 5, characterized in that: The nickel salt, cobalt salt and manganese salt in step (1) and step (2) are any one or a combination of at least two of the sulfate, nitrate or chloride salts of the corresponding metal ions; Preferably, the total concentration of metal ions in the first salt solution in step (1) and the second salt solution in step (2) is 1.6-2.4 mol / L, respectively.

7. The method according to any one of claims 4 to 6, characterized in that: The precipitant solutions in step (3) and step (4) respectively include sodium hydroxide solutions; Preferably, the concentrations of the precipitant solutions in step (3) and step (4) are 9-12 mol / L respectively; Preferably, the complexing agent solutions in step (3) and step (4) respectively include aqueous ammonia; Preferably, the concentrations of the complexing agent solutions in step (3) and step (4) are 8-10 mol / L respectively.

8. The method according to any one of claims 4 to 7, characterized in that: Step (3) During the first coprecipitation reaction, the injection rate of the first salt solution is 4-8 L / h, the injection rate of the precipitant solution is 2.2-2.6 L / h, and the injection rate of the complexing agent solution is 1-1.5 L / h; Preferably, the residence time in step (3) is 2-2.5 h; Preferably, during the second coprecipitation reaction in step (4), the injection rate of the second salt solution is 4-8 L / h, the injection rate of the precipitant solution is 2.2-2.4 L / h, the injection rate of the complexing agent solution is 0.6-1.2 L / h, and the pH of the mixed solution is maintained at 9-13 and the ammonia concentration is maintained at 3-6 g / L; Preferably, the target requirement for the particle size in step (4) is D50 ≥ 8 μm; Preferably, the temperatures of the first coprecipitation reaction in step (3) and the second coprecipitation reaction in step (4) are 40-65° C. respectively; Preferably, the first coprecipitation reaction in step (3) and the second coprecipitation reaction in step (4) are respectively carried out in an atmosphere of a protective gas, and the protective gas comprises nitrogen.

9. The method according to any one of claims 4 to 8, characterized in that: The solid-liquid separation in step (5) includes centrifugation, washing and drying; Preferably, the solid-liquid separation in step (5) further includes removing magnetic foreign matter.

10. The method according to any one of claims 3 to 9, characterized in that: The method adopts a homogenizing reactor and a stirring reactor to simultaneously carry out a coprecipitation reaction, and adopts a thickener to realize continuous reaction and particle size control, so as to obtain a core-shell precursor with a normally distributed particle size, and specifically comprises the following steps: (1) mixing nickel salt, cobalt salt, manganese salt and pure water according to the molar ratio of Ni:Co:Mn=x1:y1:z1 to obtain a first salt solution with a total metal ion concentration of 1.6-2.4 mol / L; the molar ratio satisfies: x1+y1+z1=1, and 0.8<x1<0.99, 0.01≤y1<0.1, 0.01<z1<0.1; (2) mixing nickel salt, cobalt salt, manganese salt and pure water according to the molar ratio of Ni:Co:Mn=x2:y2:z2 to obtain a second salt solution with a total metal ion concentration of 1.6-2.4 mol / L; the molar ratio satisfies: x2+y2+z2=1, and 0.5<x2<0.8, 0.01≤y2<0.4, 0.05<z2<0.25; (3) injecting the first salt solution, the precipitant solution and the complexing agent solution into a homogenizing reactor, and controlling the injection flow rate of the first salt solution to 4-8 L / h, the injection flow rate of the precipitant solution to 2.2-2.6 L / h, and the injection flow rate of the complexing agent solution to 1-1.5 L / h, performing a first coprecipitation reaction at 40-65° C. in a nitrogen atmosphere, controlling the particle size of the seed core by adjusting the residence time to 2-2.5 h, and continuously injecting into the stirring reactor; (4) injecting the second salt solution, the precipitant solution and the complexing agent solution into the stirred reactor, and controlling the injection flow rate of the second salt solution to 4-8 L / h, the injection flow rate of the precipitant solution to 2.2-2.4 L / h, and the injection flow rate of the complexing agent solution to 0.6-1.2 L / h, while maintaining the pH of the mixed solution at 9-13 and the ammonia concentration at 3-6 g / L, and conducting the second coprecipitation reaction at 40-65° C. in a nitrogen atmosphere, and starting the thickener when the liquid level reaches the thickening level, continuing the reaction until the particle size D50 is ≥8 μm, and suspending the homogenizing reactor and the stirred reactor; (5) collecting the materials in the homogenizing reactor and the stirring reactor, and then centrifuging, washing and drying them to remove the magnetic foreign matter to obtain a core-shell precursor with a normal particle size distribution; Wherein, the nickel salt, cobalt salt and manganese salt in step (1) and step (2) are any one or a combination of at least two of sulfate, nitrate or chloride salts of the corresponding metal ions; the precipitant solution in step (3) and step (4) respectively includes a sodium hydroxide solution with a concentration of 9-12 mol / L, and the complexing agent solution respectively includes ammonia water with a concentration of 8-10 mol / L.

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