Sodium-ion battery positive electrode material precursor, preparation method and application

Abstract

The present disclosure discloses a sodium-ion battery positive electrode material precursor, a preparation method and application. The main component of the sodium-ion battery positive electrode material precursor is a carbonate precursor, and a small amount of a hydroxide precursor is also introduced. The introduction of the hydroxide precursor is conducive to controlling the particle size distribution of the precursor during the preparation process of the precursor, is conducive to narrowing the particle size distribution of the carbonate precursor, and is further conducive to improving the tap density of the precursor. At the same time, a small amount of hydroxide precursor is introduced as a crystal seed during the preparation of the precursor, which is conducive to narrowing the particle size distribution of the carbonate precursor, is also conducive to improving the sphericity of the precursor, and a precursor material with small specific surface area and good fluidity is obtained.

Description

Technical Field

[0001] This disclosure relates to the field of sodium-ion battery layered oxide cathode material precursor technology, specifically to sodium-ion battery cathode material precursors, preparation methods, and applications. Background Technology

[0002] Common cathode materials for sodium-ion batteries include Prussian white, phosphate polyanionic materials, and multi-layered oxide materials. Among them, multi-layered oxide materials have ideal specific capacity, are easy to synthesize, and have cycle stability. They have certain potential advantages as cathode materials for sodium-ion batteries, and have therefore been widely studied and developed.

[0003] Layered sodium oxide cathode materials are composed of many metal ions, which have good coordination and complementary effects. Some variable valence metal ions, such as Cu ions, improve the air stability of the material. However, for copper-based multi-component hydroxide precursors, the precipitation rate is inconsistent due to the difference between Cu ions (KSP) and other ions, resulting in segregation and difficulty in uniform precipitation. This seriously affects the performance and industrialization of the synthesized material.

[0004] In sodium-ion battery materials, carbonate precursors have the advantages of high tapping and low cost, and the carbonate route can replace the hydroxide route. However, carbonate precursors also face some problems, such as poor stability of the synthesis process, difficulty in controlling the growth rate, difficulty in controlling the particle size, and uneven particle size distribution.

[0005] In view of this, this disclosure is hereby made. Summary of the Invention

[0006] The purpose of this disclosure is to provide a precursor, preparation method and application of a sodium-ion battery cathode material with high tap density.

[0007] This disclosure is implemented as follows:

[0008] In a first aspect, this disclosure provides a sodium-ion battery cathode material precursor, comprising a first precursor particle and a second precursor particle, wherein the first precursor particle is a carbonate precursor, and the second precursor particle comprises a core and a shell, wherein the core is a hydroxide precursor and the shell is a carbonate precursor.

[0009] In some embodiments, the hydroxide precursor accounts for 2%-20% of the total mass of the sodium-ion battery cathode material precursor.

[0010] In some embodiments, the D50 of the sodium-ion battery cathode material precursor is 5 μm to 20 μm.

[0011] In some embodiments, the core has a D50 of 2 μm to 8 μm.

[0012] In some embodiments, the metal element in the carbonate precursor and / or hydroxide precursor is one or a combination of two or more of Li, K, Al, Ti, Cr, Mn, Fe, Cu, Co, Ni, Zn, Sn, Zr, Mo, Nb, Y, W, In, and Ge.

[0013] Secondly, this disclosure provides a method for preparing a sodium-ion battery cathode material precursor according to any one of the foregoing embodiments. In the process of preparing carbonate precursor particles by co-precipitation, a hydroxide precursor is used as a seed crystal to adjust the particle size distribution of the carbonate precursor particles, thereby obtaining the sodium-ion battery cathode material precursor.

[0014] In some embodiments, during the preparation of carbonate precursor particles using the co-precipitation method, whenever the D50 of the precipitate reaches a preset particle size, the seed crystals are added to the reaction system, and the total mass fraction of the seed crystals in the sodium-ion battery cathode material precursor is 2%-20%.

[0015] In some embodiments, the method includes: adding a salt solution of a metal element and a carbonate solution in parallel to the base liquid to carry out a co-precipitation reaction, and adding the seed crystals to the reaction system in batches whenever the D50 of the precipitate reaches a preset particle size.

[0016] In some embodiments, ammonia water is also added to the base liquid.

[0017] In some embodiments, the ammonia concentration in the reaction solution is maintained at 0.1 g / L to 8 g / L during the coprecipitation reaction.

[0018] In some embodiments, the total concentration of the metal element in the salt solution is 0.1 mol / L to 2.5 mol / L.

[0019] In some embodiments, the total concentration of the metal element in the salt solution is 1.7 mol / L to 2.0 mol / L.

[0020] In some embodiments, the flow rate of the salt solution of the metal element is 1 L / h to 20 L / h.

[0021] In some embodiments, the concentration of the carbonate solution is 0.1 mol / L to 1.8 mol / L.

[0022] In some embodiments, the concentration of the carbonate solution is 1.5 mol / L to 1.8 mol / L.

[0023] In some embodiments, the flow rate of the carbonate solution is 8 L / h to 12 L / h.

[0024] In some embodiments, the base liquid also contains ammonia water, and the ammonia concentration in the base liquid is 0 g / L-8 g / L.

[0025] In some embodiments, the base solution also contains carbonates, and the concentration of carbonates in the base solution is 0.01 mol / L to 1.5 mol / L.

[0026] In some embodiments, the coprecipitation reaction is carried out under inert gas protection conditions.

[0027] In some embodiments, the pH value of the coprecipitation step is 8-11.

[0028] In some embodiments, the temperature of the coprecipitation reaction is 30°C-70°C.

[0029] In some embodiments, the coprecipitation reaction is carried out under stirring conditions at a stirring frequency of 30 Hz to 60 Hz.

[0030] In some embodiments, the seed crystals are added in batches over 2-5 hours.

[0031] In some embodiments, the preparation of seed crystals is also included: ammonia water is introduced into a salt solution of the metal element, and the pH value of the reaction solution is adjusted with an alkaline solution to synthesize seed crystals.

[0032] In some embodiments, the ammonia concentration in the reaction solution is maintained at 2 g / L-4 g / L during the seed crystal preparation step.

[0033] In some embodiments, the pH of the reaction solution is maintained in the range of 8-13 during the seed crystal preparation step.

[0034] In some embodiments, the temperature for preparing the seed crystal is 30°C-70°C.

[0035] In some embodiments, the alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution, and the concentration of the alkaline solution is 5 mol / L-10 mol / L.

[0036] In some embodiments, the seed crystal preparation step is carried out under stirring conditions, with a stirring frequency of 30Hz-60Hz.

[0037] Thirdly, this disclosure provides a cathode material obtained by mixing and sintering a sodium-ion battery cathode material precursor as described in any of the foregoing embodiments with a sodium source.

[0038] Fourthly, this disclosure provides a positive electrode sheet, comprising the positive electrode material described in the foregoing embodiments.

[0039] Fifthly, this disclosure provides a sodium-ion battery, including the positive electrode sheet described in the foregoing embodiments.

[0040] This disclosure has the following beneficial effects:

[0041] The sodium-ion battery cathode material precursor disclosed herein includes a carbonate precursor and a hydroxide precursor. The introduction of the hydroxide precursor is beneficial for controlling the particle size distribution of the precursor during the precursor preparation process, and for narrowing the particle size distribution of the carbonate precursor, thereby improving the tap density of the precursor. At the same time, the introduction of a small amount of hydroxide precursor as a seed crystal during the precursor preparation process is beneficial for narrowing the particle size distribution of the carbonate precursor and for improving the sphericity of the precursor, resulting in a precursor material with a small specific surface area and good flowability. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this disclosure and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 Ni obtained in Example 1 0.3 Mn 0.50 Fe 0.1 Cu 0.1 Electron micrograph of the carbonate precursor of CO3;

[0044] Figure 2 To obtain Ni in Comparative Example 1 0.3 Mn 0.50 Fe 0.1 Cu 0.1 Electron micrograph of the carbonate precursor of CO3. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions in the embodiments of this disclosure will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0046] This disclosure provides a sodium-ion battery cathode material precursor, comprising a first precursor particle and a second precursor particle. The first precursor particle is a carbonate precursor, and the second precursor particle comprises a core and a shell. The core is a hydroxide precursor, and the shell is a carbonate precursor.

[0047] In this embodiment, the precursor of the sodium-ion battery cathode material is mainly composed of a carbonate precursor, with a small amount of hydroxide precursor also introduced. The introduction of hydroxide precursor is beneficial for controlling the particle size distribution of the precursor during the precursor preparation process, and for narrowing the particle size distribution of the carbonate precursor, thereby improving the tap density and sphericity of the precursor, and improving the cycle stability of the prepared cathode material.

[0048] It should be noted that, in this embodiment, the metal elements in the hydroxide precursor and the carbonate precursor can be metal elements suitable for sodium-ion battery cathode materials. There can be one metal element or two or more metal elements. In order to improve the performance of the cathode material, two or more metal elements are usually selected. In addition, the metal elements in the hydroxide precursor and the carbonate precursor can be the same or different. In general, the same metal element is selected in the hydroxide precursor and the carbonate precursor.

[0049] In some embodiments, the hydroxide precursor accounts for 2%-20% of the total mass of the sodium-ion battery cathode material precursor. Specifically, it can be 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 5%, 10%, 15%, 20%, or any value between 2%-20% and 2%-3%. If the proportion of hydroxide precursor is too small, the improvement effect on particle size distribution will be poor; if the proportion of hydroxide precursor is too large, the problems of easy segregation inherent in the hydroxide precursor itself will affect the overall performance of the sodium-ion battery cathode material precursor in this embodiment.

[0050] In some embodiments, the D50 of the sodium-ion battery cathode material precursor is 5 μm to 20 μm, specifically it can be any value between 5 μm, 8 μm, 11 μm, 14 μm, 17 μm, 20 μm or 5 μm to 20 μm. The introduction of hydroxide precursor is beneficial to obtaining carbonate precursor particles with smaller particle size. If the cathode material precursor particle size is small, the particle size distribution range is small, and the effect of adding hydroxide to narrow the particle size distribution is relatively small.

[0051] In some embodiments, the D50 of the core is 2μm to 8μm, specifically it can be any value between 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm or 2μm to 8μm. Introducing a hydroxide precursor with a smaller particle size can allow the carbonate precursor generated during the co-precipitation process to gradually grow on the hydroxide precursor, thereby inhibiting the continuous growth of carbonate precursor particles.

[0052] In some embodiments, the metal element in the carbonate precursor and / or hydroxide precursor is one or more of the following: Li, K, Al, Ti, Cr, Mn, Fe, Cu, Co, Ni, Zn, Sn, Zr, Mo, Nb, Y, W, In, and Ge. Specifically, it can be a combination of four metal elements: Mn, Fe, Co, and Ni; a combination of three elements: Mn, Fe, and Cu; or other combinations.

[0053] Another embodiment of this disclosure provides a method for preparing a sodium-ion battery cathode material precursor according to any one of the foregoing embodiments, comprising: in the process of preparing carbonate precursor particles by co-precipitation, using a hydroxide precursor as a seed crystal to adjust the particle size distribution of the carbonate precursor particles to obtain the sodium-ion battery cathode material precursor.

[0054] In this embodiment, during the preparation of carbonate precursor particles using the co-precipitation method, small seed crystals with a particle size smaller than D50 are added to the co-precipitation system. Using the hydroxide precursor as seed crystals, the carbonate precursor will preferentially precipitate on the surface of the hydroxide precursor, thereby avoiding excessively rapid and large growth of the carbonate precursor particles. This effectively narrows the particle size distribution of carbonate, improves the stability of the preparation process, and enables the synthesis of small-particle carbonate precursors. The resulting precursor has high tap density, high sphericity, good flowability, and small specific surface area.

[0055] In some embodiments, during the preparation of carbonate precursor particles using the co-precipitation method, seed crystals are added to the reaction system whenever the D50 of the precipitate reaches the preset particle size. The total mass fraction of seed crystals in the sodium-ion battery cathode material precursor is 2%-20%. To prevent the carbonate precursor from continuing to grow, seed crystals can be added in small amounts multiple times. Under the same conditions, if a large number of batches are added, the number of additions can be appropriately reduced. In addition, under the same conditions, if the particle size of the seed crystals differs significantly from the preset particle size, the amount of seed crystals added can be relatively reduced; if the particle size of the seed crystals differs slightly from the preset particle size, the amount of seed crystals added needs to be relatively increased.

[0056] In some embodiments, the method includes: adding a salt solution and a carbonate solution of the metal element concurrently to a base liquid to perform a co-precipitation reaction, and adding the seed crystals to the reaction system in batches whenever the D50 of the precipitate reaches a preset particle size.

[0057] This embodiment introduces seed crystals to improve the controllability of the coprecipitation process, based on the original coprecipitation process.

[0058] Ammonia can be introduced as a complexing agent, which also helps maintain the pH during precipitation. Specifically, the ammonia concentration can be any value between 0 g / L, 2 g / L, 4 g / L, 6 g / L, 8 g / L, or 0 g / L-8 g / L.

[0059] In some embodiments, the ammonia concentration (calculated as NH3) in the reaction solution is maintained at 0.1 g / L-8 g / L during the co-precipitation reaction. Specifically, it can be any value between 0.1 g / L, 0.3 g / L, 0.5 g / L, 1 g / L, 3 g / L, 8 g / L, or 0.1 g / L-8 g / L. Under the same conditions, if the ammonia concentration is too high, the reaction rate will be too slow, which is not conducive to improving efficiency; if the ammonia concentration is too low, precipitation will be too fast, which may reduce the density of the particles. In some embodiments, the ammonia concentration of the ammonia water introduced into the reaction solution can be 12 g / L-25 g / L.

[0060] In some embodiments, the total concentration of the metal element in the salt solution is 0.1 mol / L to 2.5 mol / L, specifically any value between 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, or 0.1 mol / L-1 mol / L, 1 mol / L-2.5 mol / L. In some embodiments, the total concentration of the metal element in the salt solution is 1.7 mol / L to 2.0 mol / L. The concentration of the metal element affects the co-precipitation rate, the size and shape of the precipitate, etc. If the total concentration of the metal element is too high, the precipitation rate is too fast, which is not conducive to controlling the precipitation process and easily results in loose particles; if the total concentration of the metal element is too low, the precipitation rate is too slow, which is not conducive to improving production efficiency.

[0061] In some embodiments, the flow acceleration of the metal element salt solution is 1L / h-20L / h, specifically any value between 1L / h, 5L / h, 10L / h, 15L / h, 20L / h, 1L / h-8L / h, 8L / h-12L / h, and 12L / h-20L / h. Similarly, if the flow acceleration of the metal element salt solution is too fast, the co-precipitation rate is too fast, which is detrimental to the control of the precipitation process and easily results in loose particles; if the flow acceleration of the metal element salt solution is too low, the precipitation rate is too slow, which, while beneficial to improving the density of the precipitated particles, is not conducive to improving production efficiency.

[0062] In some embodiments, the concentration of the carbonate solution is 0.1 mol / L to 1.8 mol / L, specifically any value between 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 1.8 mol / L, or 0.1 mol / L to 1.8 mol / L. In some embodiments, the concentration of the carbonate solution is 1.5 mol / L to 1.8 mol / L. If the carbonate solution concentration is too high, the precipitation rate is too fast, which is not conducive to controlling the precipitation process and easily results in loose particles; if the carbonate solution concentration is too low, the precipitation rate is too slow, which is not conducive to improving production efficiency.

[0063] In some embodiments, the flow acceleration of the carbonate solution is 8 L / h to 12 L / h, specifically any value between 8 L / h, 9 L / h, 10 L / h, 11 L / h, 12 L / h, or 8 L / h to 12 L / h. Similarly, if the flow acceleration of the carbonate solution is too fast, the co-precipitation rate is too fast, which is detrimental to the control of the precipitation process and easily results in loose particles; if the flow acceleration of the carbonate solution is too low, the precipitation rate is too slow, which, while beneficial to improving the density of the precipitated particles, is not conducive to improving production efficiency.

[0064] In some embodiments, the base solution further contains ammonia water, and the ammonia concentration in the base solution is 0 g / L-8 g / L, specifically, it can be any value between 0 g / L, 2 g / L, 4 g / L, 6 g / L, 8 g / L, or 0 g / L-8 g / L. In some embodiments, the ammonia concentration is 2 g / L-4 g / L. Adding ammonia water to the base solution is beneficial for controlling the precipitation rate and for obtaining precursor particles with better sphericity.

[0065] In some embodiments, the base solution also contains carbonates, and the concentration of carbonates in the base solution is 0.01 mol / L to 1.5 mol / L.

[0066] In some embodiments, the coprecipitation reaction is carried out under an inert gas protection condition, which may be nitrogen, argon, etc. Nitrogen is usually chosen to avoid oxidation of the reactants.

[0067] In some embodiments, the pH value of the coprecipitation step is 8-11, specifically 8, 9, 10, 11 or any value between 8 and 11, and in some embodiments it is 9.5-10, which is conducive to precursor nucleation and growth.

[0068] In some embodiments, the temperature of the coprecipitation reaction is 30°C-70°C, specifically any value between 30°C, 40°C, 50°C, 60°C, 70°C or 30°C-70°C, which is conducive to precursor nucleation and growth.

[0069] In some embodiments, the coprecipitation reaction is carried out under stirring conditions at a stirring frequency of 30 Hz to 60 Hz, specifically any value between 30 Hz, 40 Hz, 50 Hz, 60 Hz or 30 Hz to 60 Hz.

[0070] In this embodiment, stirring can make the material distribution in the reaction solution relatively uniform, and increasing the stirring speed is beneficial to the uniform distribution of the product. On the other hand, during the stirring process, the particles in the reaction system may collide and rub against each other. If the stirring speed is too high, the continuous collision between the particles may cause the particles to break or crack, which is not conducive to the improvement of the quality of the precursor particles. Therefore, the stirring speed should not be too high.

[0071] In some embodiments, the seed crystals are added in batches over a period of 2-5 hours. Specifically, this time can be controlled to any value between 2 hours, 3 hours, 4 hours, 5 hours, or 2-5 hours. Generally, if the particle size of the seed crystals differs significantly from the preset D50 of the precipitate, the amount of seed crystals added can be relatively reduced, and the time between the first and last addition of seed crystals can be relatively shortened. Conversely, if the particle size of the seed crystals differs only slightly from the preset particle size, the amount of seed crystals added needs to be relatively increased, and the time required for adding the seed crystals will also be extended.

[0072] In some embodiments, the preparation of seed crystals is also included: ammonia water is introduced into a salt solution of the metal element, and the pH value of the reaction solution is adjusted with an alkaline solution to synthesize seed crystals.

[0073] According to existing technology, taking copper as an example, copper-based multi-component hydroxide precursors, due to Cu ions and K... SP The difference from other ions leads to inconsistent precipitation rates, resulting in segregation and making it difficult to precipitate uniformly. However, in this embodiment, the proportion of seed crystals is only 2%-3%, which is relatively small and has a relatively small impact on the overall performance of the precursor.

[0074] In some embodiments, the ammonia concentration in the reaction solution is maintained at 2 g / L-4 g / L during the seed crystal preparation step. Specifically, it can be any value between 2 g / L, 3 g / L, 4 g / L, or 2 g / L-4 g / L. Ammonia water acts as a complexing agent, which is beneficial for controlling the precipitation rate and for obtaining seed crystals with better sphericity.

[0075] It should be noted that increasing the ammonia concentration in the reaction solution is beneficial for obtaining finer crystals. Therefore, when preparing seed crystals, the ammonia concentration in the reaction solution can be slightly higher than that in the reaction solution during carbonate precipitation.

[0076] In some embodiments, the pH value of the reaction solution is maintained in the range of 8-13 during the seed preparation step. Specifically, it can be any value between 8, 9, 10, 11, 12, 13 or 8-13, which is conducive to seed nucleation and growth.

[0077] In some embodiments, the temperature of the seed preparation step is 30℃-70℃, specifically any value between 30℃, 40℃, 50℃, 60℃, 70℃ or 30℃-70℃, which is conducive to seed nucleation and growth.

[0078] In some embodiments, the alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution, and the concentration of the alkaline solution is 5 mol / L-10 mol / L. Specifically, it can be any value between 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, or 5 mol / L-10 mol / L, mainly used to adjust the pH of the solution.

[0079] In some embodiments, the seed crystal preparation step is carried out under stirring conditions, with a stirring frequency of 30Hz-60Hz, specifically any value between 30Hz, 40Hz, 50Hz, 60Hz or 30Hz-60Hz.

[0080] In this embodiment, stirring can make the material distribution in the reaction solution relatively uniform, and increasing the stirring speed is beneficial to the uniform distribution of the product. On the other hand, during the stirring process, the particles in the reaction system may collide and rub against each other. If the stirring speed is too high, the continuous collision between the particles may cause the particles to break or crack, which is not conducive to the improvement of the quality of the precursor particles. Therefore, the stirring speed should not be too high.

[0081] This disclosure provides a cathode material obtained by mixing and sintering a sodium-ion battery cathode material precursor as described in any of the foregoing embodiments with a sodium source.

[0082] This disclosure provides a positive electrode sheet, comprising the positive electrode material described in the foregoing embodiments.

[0083] This disclosure provides a sodium-ion battery, including the positive electrode sheet described in the foregoing embodiments.

[0084] The features and performance of this disclosure will be further described in detail below with reference to embodiments.

[0085] Example 1

[0086] This embodiment provides a method for preparing a precursor for a sodium-ion battery cathode material, specifically including the following steps:

[0087] (1)Ni 0.3 Mn 0.50 Fe 0.1 Cu 0.1 Preparation of (OH)2 seed crystals: In a reaction vessel, a metal solution with a total metal element concentration of 2 mol / L was prepared by weighing the corresponding nickel sulfate, manganese sulfate, ferrous sulfate and copper sulfate raw materials according to the molar ratio of Ni:Mn:Fe:Cu of 0.3:0.50:0.1:0.1. Ammonia water was then introduced into the reaction vessel to maintain the ammonia concentration in the vessel at 2 g / L. Liquid alkali was introduced to adjust the pH value to 10.5, and small seed crystals with a D50 of 5 μm were prepared.

[0088] (2) Synthesis of precursor materials:

[0089] Preparation of sodium carbonate solution S1: Prepare a sodium carbonate solution with a concentration of 1.8 mol / L according to experimental requirements.

[0090] S2 Reactor Bottom Liquid: Add 1 / 3 of the reactor volume of pure water to a 500L reactor, heat to 65℃, introduce N2, add sodium carbonate to the reactor bottom liquid to make the sodium carbonate concentration 0.08mol / L, and start stirring at 50Hz.

[0091] After the experimental conditions in the reactor are met, the molten metal prepared in step 1 is introduced at a rate of 10 L / h. At the same time, ammonia water is introduced to maintain the ammonia concentration in the reactor at 0.5 g / L. A 1.8 mol / L sodium carbonate solution is introduced to adjust the pH to 9.5 for nucleation and growth. When the D50 of the precipitated particles reaches 10 μm, the seed crystals prepared in step (1) are added in batches. The D50 of the particles in the reactor is continuously controlled to be 10 μm until the expected yield of 200 kg is reached. The total mass of the seed crystals added is 10 kg. Ni crystals with good particle size consistency and sphericity are prepared. 0.3 Mn 0.50 Fe 0.1 Cu 0.1 The precursor material is mainly composed of CO3 carbonate precursors, and the electron micrograph is shown below. Figure 1 As shown.

[0092] Comparative Example 1

[0093] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 did not contain Ni. 0.3 Mn 0.50 Fe 0.1 Cu 0.1 (OH)2 seed crystals were used to obtain Ni when D50 reached 10 μm. 0.3 Mn 0.50 Fe 0.1 Cu 0.1 Precursor material with CO3 carbonate precursor as the main precursor, electron micrograph as follows: Figure 2 As shown, the obtained carbonate precursor has uneven particle size distribution, poor sphericity, and the particle size cannot be controlled.

[0094] Example 2

[0095] This embodiment provides a sodium-ion battery cathode material precursor Ni 0.2 Mn 0.40 Fe 0.2 Cu 0.2 The method for preparing CO3 specifically includes the following steps:

[0096] (1)Ni 0.2 Mn 0.40 Fe 0.2 Cu 0.2 Preparation of (OH)2 seed crystals: In a reaction vessel, a metal solution with a total metal element concentration of 2 mol / L was prepared by weighing the corresponding nickel sulfate, manganese sulfate, ferrous sulfate and copper sulfate raw materials according to the molar ratio of Ni:Mn:Fe:Cu of 0.2:0.40:0.2:0.2. Ammonia water was introduced to maintain the ammonia concentration in the vessel at 2 g / L. Liquid alkali was introduced to adjust the pH value to 10.5, and small seed crystals with a D50 of 4 μm were prepared.

[0097] (2) Synthesis of precursor materials:

[0098] Preparation of sodium carbonate solution S1: Prepare a sodium carbonate solution with a concentration of 1.8 mol / L according to experimental requirements.

[0099] S2 Reactor Bottom Liquid: Add 1 / 3 of the reactor volume of pure water to a 500L reactor, heat to 70℃, introduce N2, add sodium carbonate to the reactor bottom liquid to make the sodium carbonate concentration 0.08mol / L, and start stirring at 45Hz.

[0100] After the experimental conditions in the reactor were met, the molten metal prepared in step 1 was introduced at a rate of 10 L / h. At the same time, ammonia water was introduced to maintain the ammonia concentration in the reactor at 0.5 g / L, and a 1.8 mol / L sodium carbonate solution was introduced to adjust the pH to 9.5 for nucleation and growth. When the D50 reached 12 μm, the seed crystals prepared in step (1) were added in batches, and the D50 of the particles in the reactor was continuously controlled to be 12 μm until the expected yield of 200 kg was reached. The total mass of the seed crystals added was 20 kg, and Ni with good particle size uniformity was prepared. 0.2 Mn 0.40 Fe 0.2 Cu 0.2 The precursor material is mainly composed of CO3 carbonate precursors.

[0101] Example 3

[0102] This embodiment provides a sodium-ion battery cathode material precursor Ni 0.25 Mn 0.25 Fe 0.25 Cu 0.25 The method for preparing CO3 specifically includes the following steps:

[0103] (1)Ni 0.25 Mn 0.25 Fe 0.25 Cu 0.25 Preparation of (OH)2 seed crystals: In a reaction vessel, nickel sulfate, manganese sulfate, ferrous sulfate and copper sulfate were weighed according to the molar ratio of Ni:Mn:Fe:Cu of 0.25:0.25:0.25:0.25 to prepare a metal liquid with a total metal element concentration of 1.7 mol / L. Ammonia water was introduced to maintain the ammonia concentration in the vessel at 4 g / L. Liquid alkali was introduced to adjust the pH value to 10.5, and small seed crystals with a D50 of 4 μm were prepared.

[0104] (2) Synthesis of precursor materials:

[0105] Preparation of sodium carbonate solution S1: Prepare a sodium carbonate solution with a concentration of 1.8 mol / L according to experimental requirements.

[0106] S2 Reactor Bottom Liquid: Add 1 / 3 of the reactor volume of pure water to a 500L reactor, heat to 60℃, introduce N2, add sodium carbonate to the reactor bottom liquid to make the sodium carbonate concentration 1.2mol / L, and start stirring at 45Hz.

[0107] After the experimental conditions in the reactor were met, the molten metal prepared in step 1 was introduced at a rate of 8 L / h. At the same time, ammonia water was introduced to maintain the ammonia concentration in the reactor at 2 g / L, and 1.8 mol / L sodium carbonate solution was introduced to adjust the pH to 9.5 for nucleation and growth. When the D50 of the precipitated particles reached 8 μm, the seed crystals prepared in step (1) were added in batches. The D50 of the particles in the reactor was continuously controlled to be 8 μm until the expected yield of 200 kg was reached. The total mass of the seed crystals added was 15 kg, and Ni with good particle size uniformity was prepared. 0.25 Mn 0.25 Fe 0.25 Cu 0.25 The precursor material is mainly composed of CO3 carbonate precursors.

[0108] Example 4

[0109] This embodiment provides a sodium-ion battery cathode material precursor Ni 0.20 Mn 0.20 Fe 0.30 Cu 0.30 The method for preparing CO3 specifically includes the following steps:

[0110] (1)Ni 0.20 Mn 0.20 Fe 0.30 Cu 0.30 Preparation of (OH)2 seed crystals: In a reaction vessel, nickel sulfate, manganese sulfate, ferrous sulfate and copper sulfate were weighed according to the molar ratio of Ni:Mn:Fe:Cu of 0.20:0.20:0.30:0.30 to prepare a metal liquid with a total metal element concentration of 1.7 mol / L. Ammonia water was introduced to maintain the ammonia concentration in the vessel at 4 g / L. Liquid alkali was introduced to adjust the pH value to 10.5, and small seed crystals with a D50 of 4 μm were prepared.

[0111] (2) Synthesis of precursor materials:

[0112] Preparation of sodium carbonate solution S1: Prepare a sodium carbonate solution with a concentration of 1.8 mol / L according to experimental requirements.

[0113] S2 Reactor Bottom Liquid: Add 1 / 3 of the reactor volume of pure water to a 500L reactor, heat to 60℃, introduce N2, add sodium carbonate to the reactor bottom liquid to make the sodium carbonate concentration 0.04mol / L, and start stirring at 45Hz.

[0114] After the experimental conditions in the reactor were met, the molten metal prepared in step 1 was introduced at a rate of 12 L / h, and a 1.8 mol / L sodium carbonate solution was introduced to adjust the pH to 9.5 for nucleation and growth. When the precipitated particle D50 reached 8 μm, the seed crystals prepared in step (1) were added in batches, and the particle D50 in the reactor was continuously controlled to be 8 μm until the expected yield of 200 kg was reached. The total mass of seed crystals added was 15 kg, and Ni with good particle size uniformity was prepared. 0.20 Mn 0.20 Fe 0.30 Cu 0.30 The precursor material is mainly composed of CO3 carbonate precursors.

[0115] Example 5

[0116] This embodiment provides a sodium-ion battery cathode material precursor Ni 0.333 Mn 0.333 Fe 0.333 The method for preparing CO3 specifically includes the following steps:

[0117] (1)Ni 0.33 Mn 0.33 Fe 0.33 Preparation of (OH)2 seed crystals: In a reaction vessel, a metal solution with a total metal element concentration of 1.7 mol / L was prepared by weighing out the corresponding nickel sulfate, manganese sulfate, and ferrous sulfate raw materials according to the molar ratio of Ni:Mn:Fe of 0.33:0.33:0.33. Ammonia water was introduced to maintain the ammonia concentration in the vessel at 4 g / L. Liquid alkali was introduced to adjust the pH value to 10.5, and small seed crystals with a D50 of 4 μm were prepared.

[0118] (2) Synthesis of precursor materials:

[0119] Preparation of sodium carbonate solution S1: Prepare a sodium carbonate solution with a concentration of 1.8 mol / L according to experimental requirements.

[0120] S2 Reactor Bottom Liquid: Add 1 / 3 of the reactor volume of pure water to a 500L reactor, heat to 60℃, introduce N2, add sodium carbonate to the reactor bottom liquid to make the sodium carbonate concentration 1mol / L, and start stirring at 45Hz.

[0121] After the experimental conditions in the reactor were met, the molten metal prepared in step 1 was introduced at a rate of 12 L / h, and a 1.8 mol / L sodium carbonate solution was introduced to adjust the pH to 9.5 for nucleation growth. When the precipitated particle D50 reached 8 μm, the seed crystals prepared in step (1) were added in batches, and the particle D50 in the reactor was continuously controlled to be 8 μm until the expected yield of 200 kg was reached. The total mass of seed crystals added was 12 kg, and Ni with good particle size uniformity was prepared. 0.33 Mn 0.33 Fe0.33 The precursor material is mainly composed of CO3 carbonate precursors.

[0122] Example 6

[0123] The only difference from Example 1 is that in step (1), small seed crystals with a D50 of 2 μm are prepared.

[0124] Example 7

[0125] The only difference from Example 1 is that in step (1), small seed crystals with a D50 of 8 μm are prepared.

[0126] Example 8

[0127] The only difference from Example 1 is that a carbonate precursor with a D50 of 20 μm is prepared in step (2).

[0128] Example 9

[0129] The only difference from Example 1 is that the total mass of seed crystals added in step (2) is 5 kg. According to the data in the table below, compared to Example 1, the amount of seed crystals added is reduced, the particle size control effect is weaker, and the particle size distribution is wider.

[0130] Example 10

[0131] The only difference from Example 1 is that the total mass of seed crystals added in step (2) is 20 kg. As can be seen from the data in the table below, compared with Example 1, too many seed crystals were added, resulting in too many small seed crystals and an increase in particle size, which also leads to a wide particle size distribution.

[0132] The particle size distribution, tap density, and specific surface area of ​​the carbonate precursors obtained in the above embodiments and comparative examples were tested, and the test results are shown in the table below.

[0133]

[0134]

[0135] Industrial applicability

[0136] In this embodiment, the main component of the sodium-ion battery cathode material precursor is a carbonate precursor, and a small amount of hydroxide precursor is also introduced. The introduction of hydroxide precursor is beneficial to controlling the particle size distribution of the precursor during the precursor preparation process, and is beneficial to narrowing the particle size distribution of the carbonate precursor, thereby improving the tap density of the precursor.

Claims

1. A precursor for a sodium-ion battery cathode material, characterized in that, It includes a first precursor particle and a second precursor particle. The first precursor particle is a carbonate precursor, and the second precursor particle includes a core and a shell. The core is a hydroxide precursor, and the shell is a carbonate precursor. The hydroxide precursor accounts for 2%-20% of the total mass of the sodium-ion battery cathode material precursor; the D50 of the sodium-ion battery cathode material precursor is 5μm~20μm; the D50 of the core is 2μm~8μm; the metal elements in the carbonate precursor and / or hydroxide precursor are a combination of four elements Ni, Mn, Fe and Cu, a combination of four metal elements Mn, Fe, Co and Ni, or a combination of three elements Mn, Fe and Cu.

2. A method for preparing the sodium-ion battery cathode material precursor according to claim 1, characterized in that, include: In the process of preparing carbonate precursor particles by co-precipitation, hydroxide precursor is used as seed crystal to adjust the particle size distribution of carbonate precursor particles, thereby obtaining the precursor of the sodium-ion battery cathode material.

3. The method for preparing the sodium-ion battery cathode material precursor according to claim 2, characterized in that, In the process of preparing carbonate precursor particles by coprecipitation, whenever the D50 of the precipitate reaches the preset particle size, the seed crystals are added to the reaction system. The total mass fraction of the seed crystals in the sodium-ion battery cathode material precursor is 2%-20%.

4. The method for preparing the sodium-ion battery cathode material precursor according to claim 2, characterized in that, include: A salt solution of a metal element and a carbonate solution are added concurrently to the base liquid to carry out a co-precipitation reaction. Whenever the D50 of the precipitate reaches the preset particle size, the seed crystals are added to the reaction system in batches.

5. The method for preparing the sodium-ion battery cathode material precursor according to claim 4, characterized in that, It also includes adding ammonia water to the bottom liquid, and maintaining the ammonia concentration in the reaction solution at 0.1 g / L-8 g / L during the coprecipitation reaction.

6. The method for preparing the sodium-ion battery cathode material precursor according to claim 4, characterized in that, The total concentration of the metal element in the salt solution is 0.1 mol / L to 2.5 mol / L.

7. The method for preparing the sodium-ion battery cathode material precursor according to claim 4, characterized in that, The total concentration of the metal element in the salt solution is 1.7 mol / L to 2.0 mol / L.

8. The method for preparing the sodium-ion battery cathode material precursor according to claim 4, characterized in that, The flow rate of the salt solution containing the metal element is 1 L / h to 20 L / h.

9. The method for preparing the sodium-ion battery cathode material precursor according to claim 4, characterized in that, The concentration of the carbonate solution is 0.1 mol / L to 1.8 mol / L.

10. The method for preparing the sodium-ion battery cathode material precursor according to claim 4, characterized in that, The concentration of the carbonate solution is 1.5 mol / L to 1.8 mol / L.

11. The method for preparing the sodium-ion battery cathode material precursor according to claim 4, characterized in that, The flow rate of the carbonate solution is 8 L / h to 12 L / h.

12. The method for preparing the sodium-ion battery cathode material precursor according to claim 4, characterized in that, The base liquid also contains ammonia water, and the ammonia concentration in the base liquid is 0g / L-8g / L.

13. The method for preparing the sodium-ion battery cathode material precursor according to claim 4, characterized in that, The base solution also contains carbonates, and the concentration of carbonates in the base solution is 0.01 mol / L to 1.5 mol / L.

14. The method for preparing the sodium-ion battery cathode material precursor according to claim 4, characterized in that, The coprecipitation reaction was carried out under inert gas protection conditions.

15. The method for preparing the sodium-ion battery cathode material precursor according to claim 4, characterized in that, The pH value of the coprecipitation step is 8-11.

16. The method for preparing the sodium-ion battery cathode material precursor according to claim 4, characterized in that, The temperature for the coprecipitation reaction is 30℃-70℃.

17. The method for preparing the sodium-ion battery cathode material precursor according to claim 4, characterized in that, The coprecipitation reaction was carried out under stirring conditions, with a stirring frequency of 30Hz-60Hz.

18. The method for preparing the sodium-ion battery cathode material precursor according to claim 4, characterized in that, The seed crystals are added in batches over a period of 2-5 hours.

19. The method for preparing the precursor of the sodium-ion battery cathode material according to claim 2, characterized in that, It also includes the preparation of seed crystals: ammonia water is introduced into a salt solution of a metal element, and the pH value of the reaction solution is adjusted by using an alkaline solution to synthesize seed crystals.

20. The method for preparing the sodium-ion battery cathode material precursor according to claim 19, characterized in that, In the preparation step of the seed crystals, the ammonia concentration in the reaction solution is maintained at 2 g / L-4 g / L; And / or, in the seed crystal preparation step, the pH value of the reaction solution is maintained in the range of 8-13; And / or, the temperature of the seed crystal preparation step is 30℃-70℃; And / or, the alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution, and the concentration of the alkaline solution is 5 mol / L-10 mol / L; And / or, the seed crystal preparation step is carried out under stirring conditions, with a stirring frequency of 30Hz-60Hz.

21. A positive electrode material, characterized in that, The sodium-ion battery cathode material precursor prepared by the method for preparing sodium-ion battery cathode material precursor according to any one of claims 2-20 is mixed with a sodium source and sintered.

22. A positive electrode plate, characterized in that, Includes the cathode material as described in claim 21.

23. A sodium-ion battery, characterized in that, Includes the positive electrode sheet as described in claim 22.

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