A sodium ion battery ternary precursor and preparation method thereof

Abstract

The invention discloses a method for preparing a ternary precursor for a sodium ion battery, comprising: preparing a metal mixed salt solution of nickel, ferrous iron and manganese, a sodium hydroxide solution and an ammonia solution; injecting water into a reactor, an intermediate tank and a concentrator; adding a second solution, a third solution and a reducing substance; continuously introducing a protective gas; circulating the solution; introducing a first solution, a second solution and a third solution into the reactor, reacting and preparing a crystal nucleus; after the crystal nucleus preparation is completed, clearing, reducing the pH, reducing the stirring rate, and increasing the flow rate of the first solution; after reaching the target particle size, aging and drying. The method for determining the amount of crystal nuclei of the invention prepares a sodium ion battery ternary precursor with a stable batch of narrow particle size distribution and no fine powder, which overcomes the shortcomings of a continuous method with more fine powder and a wide diameter distance, and at the same time overcomes the shortcomings of a conventional discontinuous method with poor batch stability, reduces the influence of human factors, improves work efficiency, and is suitable for large-scale continuous production.

Description

Technical Field

[0001] The present invention relates to the technical field of ternary precursors, and in particular to a ternary precursor for a sodium ion battery and a preparation method thereof. Background Art

[0002] With the development of new energy vehicles and various large-scale equipment, the demand for lithium and cobalt resources is increasing. However, the limited lithium and cobalt resources increase the cost of lithium batteries. Therefore, it is necessary to find another new energy battery to alleviate the current situation of lack of lithium and cobalt resources. Sodium-ion batteries are considered to be a beneficial supplement to lithium-ion batteries due to their low cost and abundant sources. The development of high-capacity and high-potential sodium-ion battery cathode materials is crucial for their practical application.

[0003] At present, the preparation processes of ternary precursors for sodium-ion batteries include continuous methods and conventional discontinuous methods. The advantage of the continuous method is that the ternary precursors can be prepared continuously and uninterruptedly. The disadvantage is that the prepared ternary precursors have more fine powders and poor sphericity. When sintering the positive electrode material, the small particles have a large contact area with the electrolyte, and the sodium ions migrate a short distance inside the particles, which can easily cause overcharge and over-discharge, affecting the battery life and creating safety hazards. The advantage of the conventional discontinuous method is that the prepared ternary precursors have very little fine powder. The disadvantage is that it is prepared in stages and the batch stability is poor, which is not conducive to long-term stable production.

[0004] Therefore, it is necessary to provide a method for stably preparing a sodium ion battery ternary precursor with a narrow particle size distribution and no fine powder. Summary of the invention

[0005] The present invention is based on the inventor's discovery and understanding of the following facts and problems: the sodium ion battery ternary precursor prepared by the continuous method has more fine powder and poor sphericity. The conventional discontinuous method prepares the sodium ion battery ternary precursor in stages, and the batch stability is poor, which is not conducive to long-term stable production.

[0006] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, an embodiment of the present invention provides a method for preparing a sodium ion battery ternary precursor, which uses a fixed crystal nucleus amount to prepare a batch of sodium ion battery ternary precursors with a narrow particle size distribution and no fine powder, overcomes the shortcomings of the continuous method with more fine powder and wide diameter spacing, and overcomes the shortcomings of the conventional discontinuous method with poor batch stability, reduces the influence of human factors, improves work efficiency, and is suitable for large-scale continuous production.

[0007] A method for preparing a ternary precursor for a sodium ion battery according to an embodiment of the present invention comprises the following steps:

[0008] (1) preparing a mixed salt solution of nickel, ferrous iron and manganese as a first solution; preparing a sodium hydroxide solution as a second solution; and preparing an ammonia solution as a third solution;

[0009] (2) injecting water into the reaction kettle, the intermediate tank and the concentrator; adding the second solution, the third solution and the reducing substance; continuously introducing the protective gas; and circulating the solutions in the reaction kettle, the intermediate tank and the concentrator;

[0010] (3) introducing the first solution, the second solution, and the third solution into a reaction vessel to react and prepare crystal nuclei;

[0011] (4) After the crystal nucleus preparation is completed, the solution is cleared, the pH is reduced, the stirring rate is reduced, and the flow rate of the first solution is increased;

[0012] (5) After reaching the target particle size, the product is aged and dried to obtain a ternary precursor for a sodium ion battery.

[0013] The advantages and technical effects brought by the preparation method of the sodium ion battery ternary precursor of the embodiment of the present invention are that a fixed amount of alkali, ammonia water and water are used to prepare the crystal nuclei, the amount of crystal nuclei produced in the initial stage is controlled to be consistent, and the fixed amount of crystal nuclei is used to prepare a batch of stable narrow diameter spacing and fine powder-free sodium ion battery ternary precursors, which overcomes the shortcomings of the continuous method with more fine powder and wide diameter spacing, and at the same time overcomes the shortcomings of the conventional discontinuous method with poor batch stability, reduces the influence of human factors, improves work efficiency, and is suitable for large-scale continuous production.

[0014] In some embodiments, in step (1), the total concentration of the three metal ions in the nickel, ferrous iron and manganese mixed salt solution is 0.5-2.5 mol / L; and / or, the molar ratio of nickel, ferrous iron and manganese in the nickel, ferrous iron and manganese mixed salt solution is 1-4:1-4:1-2; and / or, the concentration of the sodium hydroxide solution is 2-15 mol / L; and / or, the concentration of the ammonia solution is 2-13 mol / L; and / or, the first solution includes an additive, and the additive is at least one of sodium citrate or ascorbic acid; and / or, the concentration of the additive in the first solution is 0.01-0.1 g / L.

[0015] In some embodiments, in step (2), the volume of water injected into the reactor, the intermediate tank and the concentrator is 60%-90%, preferably 80% of the total volume of the reactor, the intermediate tank and the concentrator; the volume of the second solution added is 0.1%-0.5% of the volume of the water injected into the reactor, the intermediate tank and the concentrator; the volume of the third solution added is 0.5%-2% of the volume of the water injected into the reactor, the intermediate tank and the concentrator.

[0016] In some embodiments, in step (2), the reducing substance includes at least one of hydrazine hydrate or ascorbic acid; and / or, the volume of hydrazine hydrate added is 0.01%-0.07% of the volume of water injected into the reactor, the intermediate tank and the concentrator; and / or, after the ascorbic acid is added, the concentration of ascorbic acid in the solution is 0.01-0.1 g / L.

[0017] In some embodiments, in step (2), the protective gas is an inert gas, preferably nitrogen; and / or the solutions in the reactor, the intermediate tank and the concentrator are circulated by a diaphragm pump.

[0018] In some embodiments, in step (3), the time for preparing the crystal nucleus is 0.5-2h.

[0019] In some embodiments, the flow rate of the first solution is 3%-8%*reactor volume / h; and / or, the flow rate of the second solution is 1%-8%*reactor volume / h; and / or, the flow rate of the third solution is 0.3%-3%reactor volume / h; and / or, the temperature in the reactor is 40-80°C; and / or, during the crystal nucleus preparation process, the pH value is 10.0-14.0; and / or, the stirring rate during the crystal nucleus preparation process is 400-1000r / min.

[0020] In some embodiments, in step (4), the reaction is carried out for 1-6 hours before clearing.

[0021] In some embodiments, in step (4), the pH decrease rate is 0.01-0.05 / h, the stirring rate decrease rate is 2-30r / 6h, and the flow rate increase rate of the first solution is 0.5%-1.5%*reactor volume / 12h.

[0022] A sodium ion battery ternary precursor according to an embodiment of the present invention is prepared by the preparation method described in the above embodiment. The sodium ion battery ternary precursor according to the embodiment of the present invention has stable batches, narrow particle size distribution, and no fine powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the synthesis device used in each embodiment and comparative example.

[0024] Figure 2 This is an electron microscope image of the sodium ion battery ternary precursor prepared in Example 1 of the present invention.

[0025] Figure 3 This is an electron microscope image of the sodium ion battery ternary precursor prepared in Comparative Example 1.

[0026] Figure 4This is an electron microscope image of the sodium ion battery ternary precursor prepared in Comparative Example 2.

[0027] Figure 5 This is an electron microscope image of the sodium ion battery ternary precursor prepared in Comparative Example 2. DETAILED DESCRIPTION

[0028] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0029] A method for preparing a ternary precursor for a sodium ion battery according to an embodiment of the present invention comprises the following steps:

[0030] (1) preparing a mixed salt solution of nickel, ferrous iron and manganese as a first solution; preparing a sodium hydroxide solution as a second solution; and preparing an ammonia solution as a third solution;

[0031] (2) injecting water into the reaction kettle, the intermediate tank and the concentrator; adding the second solution, the third solution and the reducing substance; continuously introducing the protective gas; and circulating the solutions in the reaction kettle, the intermediate tank and the concentrator;

[0032] (3) introducing the first solution, the second solution, and the third solution into a reaction vessel to react and prepare crystal nuclei;

[0033] (4) After the crystal nucleus preparation is completed, the solution is cleared, the pH is reduced, the stirring rate is reduced, and the flow rate of the first solution is increased;

[0034] (5) After reaching the target particle size, the product is aged and dried to obtain a ternary precursor for a sodium ion battery.

[0035] The method for preparing a ternary precursor for a sodium ion battery in an embodiment of the present invention adopts a fixed amount of alkali, ammonia water and water to prepare the crystal nuclei, controls the initial amount of crystal nuclei to be consistent, and prepares a batch of stable sodium ion battery ternary precursors with narrow diameter spacing and no fine powder with a fixed crystal nucleus amount, thereby overcoming the shortcomings of the continuous method with more fine powder and wide diameter spacing, and at the same time overcomes the shortcomings of the conventional discontinuous method with poor batch stability, reduces the influence of human factors, improves work efficiency, and is suitable for large-scale continuous production.

[0036] In some embodiments, in step (1), the total concentration of the three metal ions in the nickel, ferrous iron and manganese mixed metal salt solution is 0.5-2.5 mol / L, specifically, for example, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L; and / or the molar ratio of nickel, ferrous iron and manganese in the nickel, ferrous iron and manganese metal salt solution is 1-4:1-4:1-2, preferably, 1:1:1; and / or the concentration of the sodium hydroxide solution is 2-15 mol / L, specifically, for example, 2 mol / L, 5 mol / L, 7 mol / L, 10 mol / L, 10.8 mol / L, 12 mol / L, 15 mol / L; and / or the concentration of the ammonia solution is 2-13 mol / L, specifically, for example, 2 mol / L, 4 mol / L, 6 mol / L, 8 mol / L, 10 mol / L, 13 mol / L. In the embodiment of the present invention, when the total concentration of the three metal ions in the metal salt solution of nickel, ferrous iron and manganese is too low, the production capacity is too low, affecting the efficiency; when it is too high, the control stability is poor and abnormal seed production occurs. The concentration of the sodium hydroxide solution needs to match the concentration of the first solution. When it is too low, the pH value cannot be adjusted in time; when it is too high, the pH value control is unstable. The flow rate of the ammonia solution is determined according to the process conditions. When the concentration is too low or too high, the alkalinity cannot be guaranteed.

[0037] In some embodiments, the first solution includes an additive, and the additive is at least one of sodium citrate or ascorbic acid; and / or the concentration of the additive in the first solution is 0.01-0.1 g / L, specifically, for example, 0.01 g / L, 0.03 g / L, 0.05 g / L, 0.07 g / L, 0.1 g / L. In the embodiment of the present invention, adding at least one of sodium citrate or ascorbic acid to the first solution can prevent the oxidation of ferrous ions and manganese ions.

[0038] In some embodiments, in step (2), the volume of water injected into the reactor, the intermediate tank and the concentrator is 60%-90% of the total volume of the reactor, the intermediate tank and the concentrator, specifically, for example, 60%, 70%, 80%, 90%, preferably, 80%; and / or, the volume of the second solution added is 0.1%-0.5% of the volume of the water injected into the reactor, the intermediate tank and the concentrator, specifically, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%; and / or, the volume of the third solution added is 0.5%-2% of the volume of the water injected into the reactor, the intermediate tank and the concentrator, specifically, for example, 0.5%, 1%, 1.5%, 2%.

[0039] In a specific embodiment, 200-500 ml of the second solution is added; and 1000-2000 ml of the third solution is added.

[0040] In the embodiment of the present invention, water is injected into the reactor, the intermediate tank and the concentrator, and the reactor, the intermediate tank and the concentrator are interconnected, and then circulated by a diaphragm pump. The amount of alkali, ammonia water and pure water added is fixed, which can ensure the consistency of the initial crystal nucleus amount and the high consistency of the final product.

[0041] In some embodiments, in step (2), the reducing substance includes at least one of hydrazine hydrate or ascorbic acid; and / or, the added volume of hydrazine hydrate is 0.01%-0.07% of the volume of water injected into the reactor, the intermediate tank and the concentrator, specifically, for example, 0.01%, 0.03%, 0.05%, 0.07%; and / or, after adding ascorbic acid, the concentration of ascorbic acid in the solution is 0.01-0.1g / L, specifically, for example, 0.01g / L, 0.03g / L, 0.05g / L, 0.07g / L, 0.1g / L. In the embodiment of the present invention, adding a reducing substance can remove dissolved oxygen in the water to ensure that it is not oxidized during the reaction process. By adjusting the amount of reducing substance added, the removal degree of dissolved oxygen in the water can be improved.

[0042] In some embodiments, in step (2), the protective gas is an inert gas, preferably nitrogen; and / or the solutions in the reactor, the intermediate tank and the concentrator are circulated by a diaphragm pump. In the embodiment of the present invention, protective gas is introduced into the reactor, the intermediate tank and the concentrator to replace the air, and the protective gas is continuously introduced during the reaction process to prevent oxidation of metal ions.

[0043] In some embodiments, in step (3), the time for preparing the crystal nucleus is 0.5-2h, specifically, 0.5h, 1h, 1.5h, 2h. In the embodiment of the present invention, by adjusting the first solution input amount, the second solution input amount, the initial total alkalinity, etc., a fixed crystal nucleus preparation time is used to prepare a batch of stable narrow diameter spacing and fine powder-free sodium ion battery ternary precursors.

[0044] In some embodiments, in step (3), the flow rate of the first solution is 3%-8%*reactor volume / h, specifically, for example, 3%, 4%, 5%, 6%, 7%, 8%; and / or, the flow rate of the second solution is 1%-8%*reactor volume / h, specifically, for example, 1%, 3%, 5%, 6%, 7%, 8%; and / or, the flow rate of the third solution is 0.3%-3%reactor volume / h, specifically, for example, 0.3%, 0.5%, 0.6%, 1%, 2%, 3%; And / or, the temperature in the reactor is 40-80°C; and / or, during the crystal nucleus preparation process, the pH value is 10.0-14.0, specifically, for example, 10.0, 11.0, 11.2, 12.0, 13.0, 14.0; and / or, during the crystal nucleus preparation process, the stirring rate is 400-1000r / min, specifically, for example, 400r / min, 600r / min, 800r / min, 816r / min, 1000r / min, preferably 816r / min.

[0045] In a specific embodiment, the flow rate of the first solution is 0.5-10 L / h; the flow rate of the second solution is 0.5-10 L / h; and the flow rate of the third solution is 0.5-30 L / h.

[0046] In the embodiment of the present invention, the amount of the initial crystal nuclei can be controlled by optimizing the amount of the first to third solutions introduced. The stirring rate is optimized during the crystal nuclei preparation process, which is conducive to effectively dispersing the initial crystal nuclei and avoiding agglomeration.

[0047] In some embodiments, in step (4), the reaction is cleared after 1-6 hours, specifically, 1h, 2h, 3h, 4h, 5h, 6h. The clearing rate is the same as the liquid inlet rate; the liquid inlet is the introduction of the first solution, the second solution, and the third solution; the clearing rate is 4.3%-19%*kettle volume / h. In the embodiment of the present invention, as the amount of slurry in the system of the first solution, the second solution, and the third solution gradually increases, the clearing function is turned on after 1-6 hours of feeding to prevent overflow. When the kettle is almost full, open the clearing function, and the clearing amount is equal to the total liquid inlet amount. If clearing is not performed and only overflow is performed, the solid content of the system cannot be improved and the physical properties of the product are unqualified.

[0048] In some embodiments, in the step (4), the pH decrease rate is 0.01-0.05 / h, specifically, for example, 0.01 / h, 0.02 / h, 0.03 / h, 0.04 / h, 0.05 / h; the stirring rate decrease rate is 2-30r / 6h, specifically, for example, 2r / 6h, 5r / 6h, 10r / 6h, 20r / 6h, 30r / 6h; the increase rate of the inlet flow rate of the first solution is 0.5%-1.5%*reactor volume / h, specifically, for example, 0.5%, 0.7%, 0.9%, 1%, 1.2%, 1.5%.

[0049] In a specific embodiment, the rate of increase of the flow rate of the first solution is 0.1-1 L / 12 h.

[0050] In the embodiment of the present invention, after the seed explosion is completed, reducing the pH, lowering the stirring rate, and increasing the flow rate of the first solution can maintain a relatively uniform growth of the particle size and improve the uniformity of the product. When the pH reduction rate is too small or does not decrease, it is easy to re-nucleate and destroy the existing system; when it is too large, it is easy to cause the particle size to agglomerate and the sphericity to be poor. When the stirring rate is reduced too small or does not decrease, it is easy to cause fine powder to be produced, and the particle size cannot grow normally; when it is too large, it is easy to cause the particle size to agglomerate and the sphericity to be poor. If the rate of increase of the flow rate of the first solution is too small, the production capacity is too low, affecting the efficiency; when it is too large, it will cause abnormal nucleation.

[0051] A sodium ion battery ternary precursor according to an embodiment of the present invention is prepared by the preparation method described in the above embodiment. The sodium ion battery ternary precursor according to the embodiment of the present invention has stable batches, narrow particle size distribution, and no fine powder.

[0052] The present invention is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0053] The schematic diagram of the synthesis device used in the following embodiments and comparative examples is as follows Figure 1 shown.

[0054] Example 1

[0055] (1) preparing a first solution, wherein the molar ratio of nickel sulfate, manganese sulfate, and ferrous sulfate is 1:1:1, and the total concentration of the metal mixed salt solution is 2.0 mol / L, adding an additive to the first solution, wherein the additive is ascorbic acid, and the concentration of the additive in the first solution is 0.05 g / L; preparing a 10.8 mol / L sodium hydroxide solution as a second solution; and preparing a 4 mol / L ammonia solution as a third solution.

[0056] (2) The volume of the reactor is 100 L, the volume of the intermediate tank is 40 L, the volume of the concentrate is 65 L, and the total volume of the reactor, the intermediate tank and the concentrate is 205 L. Pure water is injected into the reactor, the intermediate tank and the concentrate to a level of 80% of the total volume of the reactor, the intermediate tank and the concentrate. A total of 300 ml of the second solution (0.18% water volume) is added to the reactor, the intermediate tank and the concentrate. A total of 1500 ml of the third solution (0.9% water volume) is added. The reducing substance hydrazine hydrate is added, and the amount of hydrazine hydrate added is 100 ml (0.06% water volume). The reactor, the intermediate tank and the concentrate are introduced with protective gas nitrogen to replace the air, and the solution is circulated by a diaphragm pump.

[0057] (3) The first solution, the second solution, and the third solution are introduced into the reactor through the A1, A2, and A3 liquid inlet pipes for reaction to prepare the crystal nucleus. The flow rate of the first solution is controlled at 3.6 L / h (3.6%*reactor volume / h), the flow rate of the second solution is 1.34 L / h (1.34%*reactor volume / h), and the flow rate of the third solution is 1.2 L / h (1.2%*reactor volume / h). The crystal nucleus preparation time is 0.5 h, the temperature in the reactor is maintained at 65°C, the reaction pH is adjusted according to the addition of 10.8 mol / L of sodium hydroxide, the initial pH is 11.2, and then gradually decreases, the stirring speed is 816 r / min, and the protective gas is continuously introduced during the reaction to prevent metal ion oxidation.

[0058] (4) After the crystal nucleus preparation is completed, the clearing function is turned on after 3 hours of feeding. As the particle size increases, the pH decreases by 0.02 / h, the rotation speed decreases by 20r / 6h, and the first solution increases by 0.6L / 12h (0.6%*reactor volume / 12h).

[0059] (5) After the particle size reaches the standard value, the material is taken out, aged, and dried to prepare a qualified sodium ion battery ternary precursor.

[0060] Three sets of parallel experiments were conducted to prepare the sodium ion battery ternary precursor as follows:

[0061] The first set of data: D0 is 1.525μm, D10 is 2.378μm, D50 is 3.502μm, D90 is 4.892μm, and D100 is 7.476μm;

[0062] The second set of data: D0 is 1.521μm, D10 is 2.348μm, D50 is 3.498μm, D90 is 4.881μm, and D100 is 7.466μm;

[0063] The third set of data: D0 is 1.517μm, D10 is 2.332μm, D50 is 3.493μm, D90 is 4.871μm, and D100 is 7.456μm;

[0064] Among them, the electron microscope images of the second group of sodium ion battery ternary precursors are as follows Figure 2 .

[0065] From three sets of data and Figure 2 It can be seen that Example 1 uses a fixed amount of crystal cores to prepare a sodium ion battery ternary precursor, and the product has stable particle size, strong consistency, high sphericity, low diameter distance, no fine powder, and stable particle size between batches.

[0066] Example 2

[0067] (1) preparing a first solution, wherein the molar ratio of nickel sulfate, manganese sulfate, and ferrous sulfate is 1:1:1, and the total concentration of the metal mixed salt solution is 1.5 mol / L; preparing a 5 mol / L sodium hydroxide solution as a second solution; and preparing an 8 mol / L ammonia solution as a third solution.

[0068] (2) The volume of the reactor is 100 L, the volume of the intermediate tank is 40 L, the volume of the concentrate is 65 L, and the total volume of the reactor, the intermediate tank and the concentrate is 205 L. Pure water is injected into the reactor, the intermediate tank and the concentrate to a level of 80% of the total volume of the reactor, the intermediate tank and the concentrate. A total of 500 ml of the second solution (0.3% water volume) is added to the reactor, the intermediate tank and the concentrate. A total of 1000 ml of the third solution (0.6% water volume) is added. The reducing substance hydrazine hydrate is added, and the amount of hydrazine hydrate added is 100 ml (0.06% water volume). The reactor, the intermediate tank and the concentrate are introduced with protective gas nitrogen to replace the air, and the solution is circulated by a diaphragm pump.

[0069] (3) The first solution, the second solution, and the third solution are introduced into the reactor through the A1, A2, and A3 liquid inlet pipes for reaction and preparation of crystal nuclei. The flow rate of the first solution is controlled to be 6 L / h (6%*reactor volume / h), the flow rate of the second solution is 1.8 L / h (1.8%*reactor volume / h), and the flow rate of the third solution is 1.5 L / h (1.5%*reactor volume / h). The crystal nucleus preparation time is 1 hour, the temperature in the reactor is maintained at 40°C, the reaction pH is adjusted according to the addition of 5 mol / L sodium hydroxide, initially 11.0, and then gradually decreased, the stirring speed is 1000 r / min, and protective gas is continuously introduced during the reaction to prevent metal ion oxidation.

[0070] (4) After the crystal nucleus preparation is completed, the clearing function is turned on after 1 hour of feeding. As the particle size increases, the pH decreases by 0.05 / h, the rotation speed decreases by 25r / 6h, and the first solution increases by 1L / 12h (1%*reactor volume / 12h).

[0071] (5) After the particle size reaches the standard value, the material is taken out, aged, and dried to prepare a qualified sodium ion battery ternary precursor.

[0072] Comparative Example 1

[0073] (1) preparing a first solution, wherein the molar ratio of nickel sulfate, manganese sulfate, and ferrous sulfate is 1:1:1, and the total concentration of the metal mixed salt solution is 2.0 mol / L; adding an additive to the first solution, wherein the additive is ascorbic acid, and the concentration of the additive in the first solution is 0.05 g / L; preparing a 10.8 mol / L sodium hydroxide solution as a second solution, and preparing a 4 mol / L ammonia solution as a third solution.

[0074] (2) The volume of the reactor is 100 L, the volume of the intermediate tank is 40 L, the volume of the concentrate is 65 L, and the total volume of the reactor, the intermediate tank and the concentrate is 205 L. Pure water is injected into the reactor, the intermediate tank and the concentrate to a level of 80% of the total volume of the reactor, the intermediate tank and the concentrate, a total of 300 ml of the second solution (0.18% water volume) is added to the reactor, the intermediate tank and the concentrate, a total of 1500 ml of the third solution (0.9% water volume) is added, and a reducing substance, hydrazine hydrate, is added, and the amount of hydrazine hydrate added is 100 ml (0.06% water volume); protective gas is introduced into the reactor, the intermediate tank and the concentrate to replace the air, and the solution is circulated by a diaphragm pump.

[0075] (3) The first solution, the second solution, and the third solution are introduced into the reactor at appropriate flow rates through the A1, A2, and A3 inlet pipes for reaction. The flow rate of the first solution is controlled at 4.8 L / h (4.8%*reactor volume / h), the flow rate of the second solution is 1.78 L / h (1.78%*reactor volume / h), and the flow rate of the third solution is 1.6 L / h (1.6%*reactor volume / h). The temperature in the reactor is maintained at 65°C, the reaction pH is adjusted according to the second solution, the stirring speed is controlled at 816 r / min, and protective gas is continuously introduced during the reaction to prevent oxidation of metal ions.

[0076] (4) During the entire feeding process, the reactor overflow valve is opened without opening the purge valve.

[0077] (5) After the particle size reaches the standard value, the material is taken out and a qualified sodium electrode precursor is prepared through a fixed aging and drying process.

[0078] Electron microscope image of sodium ion battery ternary precursor Figure 3, D0 is 0.346μm, D10 is 1.758μm, D50 is 3.554μm, D90 is 5.552μm, and D100 is 7.876μm. It can be seen that the diameter distribution of the sodium-ion battery ternary precursor is wide, the particle size distribution is not good, the primary morphology layer is thin, the sphericity is poor, and the physical and chemical indicators are unqualified.

[0079] Comparative Example 2

[0080] The preparation method of Comparative Example 2 is the same as that of Example 1, except that, in the step (2), pure water is injected into the reactor, the intermediate tank and the concentrator to a liquid level of 80% of the total volume of the reactor, the intermediate tank and the concentrator, the second solution and the third solution are added to the reactor, the intermediate tank and the concentrator, the pH is controlled to be 11.65 by external detection equipment, the alkalinity is adjusted to 5 g / L, and the reducing substance hydrazine hydrate is added, and the amount of hydrazine hydrate added is 100 ml (0.06% water volume); protective gas is introduced into the reactor, the intermediate tank and the concentrator to replace the air, and the solution is circulated by a diaphragm pump.

[0081] In Comparative Example 2, the pH was controlled to be 11.65 using external detection equipment, and the alkalinity was adjusted to 5 g / L. The pH value is affected by many factors in actual production and has poor stability. There are deviations in the detection of the initial crystal nucleus preparation pH and the initial crystal nucleus preparation amount.

[0082] The first set of data: D0 is 1.475μm, D10 is 2.438μm, D50 is 3.532μm, D90 is 4.995μm, and D100 is 7.567μm. Figure 4 .

[0083] The second set of data: D0 is 1.635μm, D10 is 2.321μm, D50 is 3.628μm, D90 is 4.886μm, and D100 is 7.566μm. Figure 5 .

[0084] It can be seen that the batch stability of the two sets of data is poor, and the granularity of each batch varies greatly.

[0085] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0086] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A method for preparing a ternary precursor for a sodium ion battery, characterized in that: The following steps are involved: (1) preparing a mixed metal salt solution of nickel, ferrous iron and manganese as a first solution; preparing a sodium hydroxide solution as the second solution; preparing an ammonia solution as the third solution; (2) Injecting water into the reactor, intermediate tank and concentrator; adding the second solution, the third solution, and the reducing substance; The protective gas is continuously introduced; the solution in the reactor, the intermediate tank and the concentrator is circulated; The volume of the second solution added is 0.1%-0.5% of the volume of the water injected into the reactor, the intermediate tank and the concentrator; the volume of the water injected into the reactor, the intermediate tank and the concentrator is 60%-90% of the total volume of the reactor, the intermediate tank and the concentrator; the volume of the third solution added is 0.5%-2% of the volume of the water injected into the reactor, the intermediate tank and the concentrator; (3) introducing the first solution, the second solution and the third solution into the reactor to react and prepare the crystal nuclei; the flow rate of the second solution is 1%-8%*the volume of the reactor / h; the flow rate of the first solution is 3%-8%*the volume of the reactor / h; the flow rate of the third solution is 0.3%-3%*the volume of the reactor / h; the time for the crystal nuclei preparation is 0.5-2h; (4) After the crystal nucleus preparation is completed, the solution is cleared, the pH is reduced, the stirring rate is reduced, and the flow rate of the first solution is increased; the pH reduction rate is 0.01-0.05 / h, the stirring rate reduction rate is 2-30r / 6h, and the flow rate of the first solution is increased by 0.5%-1.5%*reactor volume / 12h; (5) After reaching the target particle size, the resulting mixture is aged and dried to obtain a ternary precursor for a sodium ion battery.

2. The method for preparing a ternary precursor for a sodium ion battery according to claim 1, characterized in that: In the step (1), the total concentration of the three metal ions in the nickel, ferrous iron and manganese mixed salt solution is 0.5-2.5 mol / L; and / or, the molar ratio of nickel, ferrous iron and manganese in the nickel, ferrous iron and manganese mixed salt solution is 1-4:1-4:1-2; and / or, the concentration of the sodium hydroxide solution is 2-15 mol / L; and / or, the concentration of the ammonia solution is 2-13 mol / L; and / or, the first solution includes an additive, and the additive is at least one of sodium citrate or ascorbic acid; and / or, the concentration of the additive in the first solution is 0.01-0.1 g / L.

3. The method for preparing a ternary precursor for a sodium ion battery according to claim 1, characterized in that: In the step (2), the volume of water injected into the reactor, the intermediate tank and the concentrator is 80% of the total volume of the reactor, the intermediate tank and the concentrator.

4. The method for preparing a ternary precursor for a sodium ion battery according to claim 1, characterized in that: In the step (2), the reducing substance comprises at least one of hydrazine hydrate and ascorbic acid; and / or, the volume of hydrazine hydrate added is 0.01%-0.07% of the volume of water injected into the reactor, the intermediate tank and the concentrator; and / or, after the ascorbic acid is added, the concentration of ascorbic acid in the solution is 0.01-0.1 g / L.

5. The method for preparing a ternary precursor for a sodium ion battery according to claim 1, characterized in that: In the step (2), the protective gas is an inert gas; and / or the solutions in the reactor, the intermediate tank and the concentrator are circulated by a diaphragm pump.

6. The method for preparing a ternary precursor for a sodium ion battery according to claim 5, characterized in that: In the step (2), the protective gas is nitrogen.

7. The method for preparing a ternary precursor for a sodium ion battery according to claim 1, characterized in that: In the step (3), the temperature in the reaction kettle is 40-80° C.; and / or, during the crystal nucleus preparation process, the pH value is 10.0-14.0; and / or, during the crystal nucleus preparation process, the stirring rate is 400-1000 r / min.

8. The method for preparing a ternary precursor for a sodium ion battery according to claim 1, characterized in that: In the step (4), the reaction is carried out for 1-6 hours before clearing.

9. A sodium ion battery ternary precursor, characterized in that: The method is prepared according to any one of claims 1 to 8.

Images