Nickel-manganese-copper-iron carbonate precursor, preparation method and application in preparation of sodium-ion battery cathode material

Abstract

The present disclosure discloses a nickel-manganese-copper-iron carbonate precursor, a preparation method and an application in preparation of a sodium-ion battery positive electrode material, which can realize complexation of Ni 2+ , Mn 2+ , Fe 2+ , Cu 2+ four metal ions and slow release under the action of a precipitant, co-precipitation of the four metal ions, uniform morphology of the prepared precursor without segregation, reduction of sodium, sulfur and other impurities in the precipitated product through post-treatment of the product, and increase of the copper content in the precursor.

Description

Technical Field

[0001] This disclosure relates to the field of sodium-ion battery cathode material technology, and more specifically, to nickel-manganese-copper-iron carbonate precursors, preparation methods, and their applications in the preparation of sodium-ion battery cathode materials. Background Technology

[0002] Currently, lithium-ion batteries are the primary candidate for energy storage systems. Introducing lithium-ion batteries into the automotive market as the preferred battery for hybrid electric vehicles, plug-in hybrid electric vehicles, and electric vehicles can reduce dependence on fossil fuels. With the large-scale application of lithium-ion batteries, the demand for lithium continues to increase; it is estimated that currently exploitable lithium resources can only last for approximately 65 years. Compared to lithium-ion batteries, sodium-ion batteries utilize abundant, inexpensive, and environmentally friendly sodium resources. Therefore, vigorously developing sodium-ion batteries will help promote the development of large-scale energy storage.

[0003] The key to sodium-ion batteries is the cathode material. Sodium-ion cathode materials prepared using layered nickel-manganese-copper-iron precursors show great promise due to their advantages such as wide availability of raw materials, low cost, excellent cycle performance, and high safety. The co-precipitation method for preparing precursors is simple to operate, easy to control morphology, and low in cost. However, the nickel-manganese-copper-iron quaternary carbonate system suffers from significant differences in precipitation coefficients among the four carbonates, and the presence of Fe... 2+ Cu 2+ With CO3 2- The reaction in solution can generate multiple products. The complex reaction process prevents the co-precipitation of the four metal ions, resulting in significant segregation of the particles. Furthermore, the precursor preparation process suffers from low Cu precipitation during the reaction, and a persistently high residual Na content in the particles after post-processing. This elemental segregation in the precursor material can transfer to the cathode material, causing significant problems for sodium-ion batteries, such as low capacity and poor cycle performance. The low precipitation rate causes the elemental ratio between the precursor and cathode material to deviate from the target value, and the high residual Na content in the particles necessitates adjustments to the Na-to-precursor ratio during subsequent cathode material preparation, affecting batch stability.

[0004] Based on the above research, it is necessary to develop a method for synthesizing nickel-manganese-copper-iron quaternary carbonate precursors with uniform morphology, elemental ratios that meet set values, and low residual Na content, thereby improving the electrochemical performance and batch stability of cathode materials.

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

[0006] The purpose of this disclosure is to provide a nickel-manganese-copper-iron carbonate precursor, a preparation method, and its application in the preparation of cathode materials for sodium-ion batteries, thereby achieving Ni 2+ Mn2+ Fe 2+ Cu 2+ The simultaneous precipitation of four metal ions, and the relatively small deviation of the proportion of each element in the precursor from the target value, are beneficial for controlling the performance of the cathode material.

[0007] This disclosure is implemented as follows:

[0008] In a first aspect, this disclosure provides a method for preparing a nickel-manganese-copper-iron carbonate precursor, comprising:

[0009] Coprecipitation: Gradually add a solution containing Ni to the base solution containing sodium carbonate and a complexing agent. 2+ Mn 2+ Fe 2+ Cu 2+ A solution of four metal ions, a complexing agent solution, and a sodium carbonate solution are used to maintain the pH of the reaction solution between 8.0 and 11.0 for co-precipitation and aging. The reaction solution is then subjected to solid-liquid separation to obtain carbonate particles. The complexing agent is at least one of sodium citrate, citric acid, sodium oxalate, and EDTA.

[0010] Post-processing: The carbonate particles, washed until their surface is neutral, are immersed in an aqueous solution of copper salt, followed by solid-liquid separation and washing of the solid phase to obtain a nickel-manganese-copper-iron carbonate precursor.

[0011] In some embodiments, the concentration of sodium carbonate in the base solution is 0.01 mol / L to 0.5 mol / L.

[0012] In some embodiments, the concentration of the complexing agent in the substrate is equal to the concentration of the complexing agent in the reaction solution.

[0013] In some embodiments, Ni in the metal ion solution 2+ Mn 2+ Fe 2+ Cu 2+ The total concentration of the four metal ions is 1.0 mol / L-2.0 mol / L, and the metal ion solution is a metal sulfate solution.

[0014] In some embodiments, the molar amount of the complexing agent in the complexing agent solution is the same as the molar amount of Ni in the metal ion solution. 2+ Mn 2+ Fe 2+ Cu 2+ The ratio of the total molar amounts of the four metal ions is (0.005-0.2):1.

[0015] In some embodiments, the molar amount of sodium carbonate added to the substrate is related to the amount of Ni added. 2+ Mn 2+Fe 2+ Cu 2+ The ratio of the total molar amounts of the four metal ions is (1.2-2.0):1.

[0016] In some embodiments, the concentration of sodium carbonate in the sodium carbonate solution is 1.0 mol / L to 1.8 mol / L.

[0017] In some embodiments, the temperature of the co-precipitation step is 30°C-80°C, and the time is 12h-48h.

[0018] In some embodiments, the aging step is performed at a temperature of 30°C-80°C for a time of 0h-24h.

[0019] In some embodiments, metal ion solution, complexing agent solution and sodium carbonate solution are added to the base liquid until the ratio of the reaction liquid volume to the base liquid volume is 2-0.5:1. Then, the mixture is purified by filter rod or concentrated by a concentrator to maintain the ratio of the reaction liquid volume to the base liquid volume at 2-0.5:1.

[0020] In some embodiments, the flow rate of the metal ion solution is 0.05 L / h to 0.2 L / h relative to the bottom liquid.

[0021] In some embodiments, the copper salt is copper sulfate or copper nitrate, and the concentration of the copper salt in the aqueous solution is 0.001 mol / L to 0.05 mol / L.

[0022] In some embodiments, the total molar amount of copper salt in the aqueous solution of the copper salt is (z-z0)n / K, in mol; where z is the coefficient of copper in the target precursor; z0 is the coefficient of copper in the carbonate particles; n is the molar amount of carbonate particles soaked in the aqueous solution of the copper salt, in mol; and K is a constant and K∈(0.6-0.8).

[0023] In some embodiments, the soaking step lasts for 1-24 hours and is carried out at a temperature of 30°C-80°C.

[0024] In some embodiments, the soaking step is accompanied by stirring at a speed of 100 r / min to 300 r / min.

[0025] In some embodiments, the washing step includes sequentially performing a water wash, an ammonium bicarbonate solution wash, and a water wash.

[0026] In some embodiments, the temperature of the washing solution in the washing step is 30°C-80°C.

[0027] In some embodiments, the ammonium salt concentration in the ammonium bicarbonate solution is 0.2 mol / L to 1.0 mol / L, and the amount of ammonium bicarbonate used is 10% to 40% of the mass of the solid phase to be washed.

[0028] In some embodiments, the solid is dried after the washing step at a temperature of 80°C-120°C for 24-48 hours until the sample moisture content is less than 2 wt%.

[0029] Secondly, this disclosure provides a nickel-manganese-copper-iron carbonate precursor obtained by the method described in any one of the foregoing embodiments, with the general formula Ni x Mn y Cu z Fe 1-x-y-z CO3, where 0≤x≤0.30, 0.30<y≤0.70, and 0<z≤0.30.

[0030] Thirdly, this disclosure provides the application of a nickel-manganese-copper-iron carbonate precursor obtained by any of the foregoing embodiments in the preparation of cathode materials for ion batteries.

[0031] This disclosure has the following beneficial effects:

[0032] This disclosure enables the realization of Ni 2+ Mn 2+ Fe 2+ Cu 2+ The complexation of four metal ions allows them to be slowly released under the action of a precipitant, achieving co-precipitation of the four metal ions. This results in a precursor with uniform morphology and no segregation. Furthermore, the particle size can be effectively controlled by adjusting the co-precipitation time and the concentration of each reagent, thereby improving the sphericity of the precursor particles in the later stages of formation.

[0033] This disclosure describes a post-treatment step for the precipitated product, in which the precipitated product is soaked in an aqueous solution of copper salt to allow Cu to... 2+ With residual CO3 in the particles 2- Combined, this supplements the Cu content in the precursor material.

[0034] This disclosure discloses a post-treatment step for the precipitated product, in which the precipitated product is soaked in an aqueous solution of copper salt to dissolve the impurity elements in the precipitated product, thereby reducing the impurity content in the precursor and improving the batch stability and overall performance of the precursor material. Attached Figure Description

[0035] 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.

[0036] Figure 1 This is a flowchart of the method for preparing the nickel-manganese-copper-iron carbonate precursor disclosed herein;

[0037] Figure 2 The image shows the SEM image of the precursor obtained in Example 1.

[0038] Figure 3 The image shows the SEM image of the precursor obtained in Example 2.

[0039] Figure 4 Here is a SEM image of the precursor obtained in Comparative Example 1;

[0040] Figure 5 The image shows the SEM image of the precursor obtained in Comparative Example 2. Detailed Implementation

[0041] 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.

[0042] Firstly, this disclosure provides a method for preparing a nickel-manganese-copper-iron carbonate precursor, such as... Figure 1 As shown, it includes:

[0043] Coprecipitation: Gradually add a solution containing Ni to the base solution containing sodium carbonate and a complexing agent. 2+ Mn 2+ Fe 2+ Cu 2+ A solution of four metal ions, a complexing agent solution, and a sodium carbonate solution are used to maintain the pH of the reaction solution between 8.0 and 11.0 for co-precipitation and aging. The reaction solution is then subjected to solid-liquid separation to obtain carbonate particles. The complexing agent is at least one of sodium citrate, citric acid, sodium oxalate, and EDTA.

[0044] Post-processing: The carbonate particles, washed until their surface is neutral, are immersed in an aqueous solution of copper salt, followed by solid-liquid separation and washing of the solid phase to obtain a nickel-manganese-copper-iron carbonate precursor.

[0045] The nickel-manganese-copper-iron quaternary carbonate system suffers from significant differences in precipitation coefficients among the four carbonates, and Fe... 2+ Cu 2+ With CO3 2- The reaction in solution can produce multiple products. The complex reaction process prevents the co-precipitation of the four metal ions, resulting in significant segregation of the particles. In the preparation of precursor materials, ammonia is often used as a complexing agent to facilitate the co-precipitation of different metal ions, but Mn... 2+ The coordination effect with NH3 is poor. Applying ammonia water to the co-precipitation process of nickel, manganese, copper, and iron quaternary carbonates will exacerbate the segregation of Mn, generating individual MnCO3 particles. Therefore, this disclosure maintains the pH of the reaction solution between 8.0 and 11.0 by adjusting the amount of sodium carbonate and the type and amount of complexing agent in the base solution, along with controlling the amount of metal ions, complexing agent, and sodium carbonate added to the base solution. Specifically, it can be any value between 8.0, 9.0, 10.0, 11.0, or 8.0-11.0, thereby achieving the desired Ni concentration. 2+ Mn 2+ Fe 2+ Cu 2+ The complexation of four metal ions allows them to be slowly released under the action of a precipitant, achieving co-precipitation of the four metal ions. This results in a precursor with uniform morphology and no segregation. Furthermore, by adjusting the co-precipitation and aging time as well as the concentration of each reagent, the particle size can be effectively controlled, thereby improving the sphericity of the precursor particles in the later stages of formation.

[0046] Considering the problem of low Cu precipitation rate during precursor preparation, resulting in lower-than-expected element content in sample particles, this disclosure addresses this issue by implementing a post-treatment step for the precipitated product. The precipitated product is immersed in an aqueous solution of copper salt to reduce Cu content. 2+ With residual CO3 in the particles 2- Combined, this supplements the Cu content in the precursor material.

[0047] During the co-precipitation or aging process, the Na in the solution + SO4 2- CO3 2- It will enter the sample particles, Na + SO4 2-The presence of sulfur (S) negatively impacts the electrochemical performance of the precursor. Conventional washing processes use alkaline washing to reduce S content and water washing to remove Na from the sample. However, during carbonate washing, while the S content is reduced to around 1000 ppm, the Na content remains around 10000 ppm. This disclosure addresses this issue by employing a post-treatment step in the precipitate, immersing the precipitate in an aqueous solution of copper salts. This process dissolves impurities such as sodium and sulfur from the precipitate, thereby reducing the content of these impurities in the precursor and improving the batch stability and overall performance of the precursor material.

[0048] In some embodiments, the concentration of sodium carbonate in the substrate is 0.01 mol / L to 0.5 mol / L, specifically any value between 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, or 0.01 mol / L to 0.5 mol / L. Sodium carbonate serves two purposes: firstly, it acts as a reactant to combine with metal ions to produce carbonate precipitates; secondly, it can adjust the pH of the reaction solution to meet the requirements of Ni. 2+ Mn 2+ Fe 2+ Cu 2+ The need for co-precipitation of four metal ions.

[0049] In some embodiments, the concentration of the complexing agent in the base solution is equal to the concentration of the complexing agent in the reaction solution. Specifically, it is c1n1c2v1 / (c1n2v1+c2v1+c2v2), in mol / L; where c1 is the total concentration of the four metal ions in the metal ion solution, in mol / L; and n1 is the molar amount of the complexing agent and the concentration of Ni in the metal ion solution. 2+ Mn 2+ Fe 2+ Cu 2+ The ratio of the total molar amounts of the four metal ions; c2 is the concentration of sodium carbonate in the sodium carbonate solution, in mol / L; v1 is the flow acceleration of the metal ion solution, in L / h; v2 is the flow acceleration of the complexing agent solution added alone, in L / h; n2 is the ratio of the molar amount of sodium carbonate added to the bottom solution to the molar amount of Ni added. 2+ Mn 2+ Fe 2+ Cu 2+ The ratio of the total molar amounts of the four metal ions. The presence of a complexing agent helps to unify the precipitation coefficients of the target product to a similar order of magnitude, achieving co-precipitation of the four metal ions. If the amount of complexing agent is too much or too little, some metal elements will not be able to precipitate simultaneously with the other metal ions.

[0050] In some embodiments, Ni in the metal ion solution 2+Mn 2+ Fe 2+ Cu 2+ The total concentration of the four metal ions is 1.0 mol / L-2.0 mol / L, specifically 1.0 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2.0 mol / L, or any value between 1.0 mol / L and 2.0 mol / L. The metal ion solution is a metal sulfate solution. The total concentration of the four metal ions affects the reaction rate. If the reaction rate is too fast, there will be more impurities in the precipitate, making it difficult to control the morphology of the precursor, which in turn affects the electrochemical performance of the final cathode material.

[0051] During the co-precipitation or aging process, the Na in the solution + SO4 2- CO3 2- It will enter the sample particles, Na + SO4 2- The presence of sulfur (S) negatively impacts the electrochemical performance of the precursor. Conventional washing processes use alkaline washing to reduce S content and water washing to remove Na from the sample. However, during carbonate washing, while the S content is reduced to around 1000 ppm, the Na content remains around 10000 ppm. This disclosure addresses this issue by employing a post-treatment step in the precipitate, immersing the precipitate in an aqueous solution of copper salts. This process dissolves impurities such as sodium and sulfur from the precipitate, thereby reducing the content of these impurities in the precursor and improving the batch stability and overall performance of the precursor material.

[0052] In this embodiment, the total concentration of the four metal ions is 1.0 mol / L-2.0 mol / L, Ni 2+ Mn 2+ Fe 2+ Cu 2+ The concentration ratio can be adjusted by those skilled in the art based on the composition of the target precursor, for example, if the target precursor composition is Ni. 0.15 Mn 0.60 Cu 0.15 Fe 0.1 CO3, then Ni 2+ Mn 2+ Fe 2+ Cu 2+ The concentration ratio is 0.15:0.6:0.15:0.1.

[0053] In some embodiments, the molar amount of the complexing agent in the complexing agent solution is the same as the molar amount of Ni in the metal ion solution. 2+ Mn 2+ Fe 2+ Cu 2+The ratio of the total molar amounts of the four metal ions is (0.005-0.2):1, specifically any value between 0.005:1, 0.01:1, 0.1:1, 0.2:1, or (0.005-0.2):1.

[0054] In some embodiments, the molar amount of sodium carbonate added to the substrate is related to the amount of Ni added. 2+ Mn 2+ Fe 2+ Cu 2+ The total molar ratio of the four metal ions is (1.2-2.0):1, specifically 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, or any value between (1.2-2.0):1. Normally, adding sodium carbonate according to the above ratio will maintain the pH of the reaction solution between 8.0 and 11.0. However, if the pH exceeds this range under certain reaction conditions, additional sodium carbonate solution can be added to adjust the pH.

[0055] In some embodiments, the concentration of sodium carbonate in the sodium carbonate solution is 1.0 mol / L to 1.8 mol / L, specifically any value between 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L or 1.0 mol / L to match the amount of metal salt and complexing agent used.

[0056] In some embodiments, the temperature of the co-precipitation step is 30°C-80°C, specifically any value between 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, or 30°C-80°C, and the time is 12h-48h, specifically any value between 12h, 18h, 24h, 30h, 36h, 42h, 48h, or 12h-48h.

[0057] In some embodiments, the aging step is performed at a temperature of 30°C-80°C, specifically any value between 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or 30°C-80°C, and for a time of 0h-24h, specifically any value between 0h, 6h, 12h, 18h, 24h or 0h-24h.

[0058] In some embodiments, after adding metal ion solution, complexing agent solution, and sodium carbonate solution to the base liquid until the ratio of reaction liquid volume to base liquid volume is 2-0.5:1, the mixture is then concentrated using a filter rod or a concentrator to maintain the ratio of reaction liquid volume to base liquid volume at 2-0.5:1. Specifically, this ratio can be any value between 2:1, 1.5:1, 1:1, 0.5:1, or (2-0.5):1.

[0059] In some specific embodiments, the base liquid is first added to the reaction vessel, and then the metal ion solution, complexing agent solution and sodium carbonate solution are added to it. Since continuous stirring is required during the co-precipitation process, in order to ensure the stirring effect, the amount of base liquid is usually enough to cover the stirring paddle in the reaction vessel. The volume of the base liquid is usually 1 / 3 to 2 / 3 of the reaction vessel volume.

[0060] In some embodiments, the flow rate of the metal ion solution relative to each liter of base liquid is 0.05 L / h-0.2 L / h; the flow rate of the complexing agent solution is c1v1n1 / c3, in L / h; and the flow rate of the sodium carbonate solution is c1v1n2 / c2, in L / h; where c1 is the total concentration of the four metal ions in the metal ion solution, in mol / L; and n1 is the molar amount of the complexing agent and the amount of Ni in the metal ion solution. 2+ Mn 2+ Fe 2+ Cu 2+ The ratio of the total molar amounts of the four metal ions; v1 is the flow acceleration of the metal ion solution, in L / h; c3 is the concentration of the complexing agent in the complexing agent solution, in mol / L; c2 is the concentration of sodium carbonate in the sodium carbonate solution, in mol / L; n2 is the ratio of the molar amount of sodium carbonate added to the base solution to the molar amount of Ni added. 2+ Mn 2+ Fe 2+ Cu 2+ The ratio of the total molar amounts of the four metal ions.

[0061] In some embodiments, the copper salt is copper sulfate or copper nitrate, and the concentration of the copper salt in the aqueous solution is 0.001 mol / L to 0.05 mol / L, specifically any value between 0.001 mol / L, 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, or 0.001 mol / L to 0.05 mol / L, which is beneficial for the combination of copper ions with free carbonate ions in the precipitate product.

[0062] In some embodiments, the total molar amount of copper salt in the aqueous solution of the copper salt is (z-z0)n / K, in mol; where z is the coefficient of copper in the target precursor; z0 is the coefficient of copper in the carbonate particles; n is the molar amount of carbonate particles soaked in the aqueous solution of the copper salt, in mol; and K is a constant and K∈(0.6-0.8).

[0063] In aqueous solutions of copper salts, not all copper can enter the carbonate particles. When the difference in the number of copper ions in the target precursor and the number of copper ions in the carbonate particles is significant, the amount of copper ions in the solution needs to be appropriately higher. Conversely, if the difference in the number of copper ions in the target precursor and the number of copper ions in the carbonate particles is small, the amount of copper ions in the solution should not be excessive to avoid over- or under-supplementation of copper. Specifically, K can be selected from any value between 0.60, 0.65, 0.70, 0.75, 0.80, or 0.6-0.8.

[0064] In some embodiments, the soaking time is 1h-24h, specifically any value between 1h, 6h, 12h, 18h, 24h, or 1h-24h, and the temperature is 30℃-80℃, specifically any value between 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, or 30℃-80℃. Under these conditions, on the one hand, copper ions have sufficient time to enter the interior of the carbonate particles, which is beneficial to ensuring the copper supplementation effect; on the other hand, elements such as sodium and sulfur mixed in the carbonate particles can also be fully dissolved, reducing the content of impurities in the precursor.

[0065] In some embodiments, the soaking step is accompanied by stirring, and the stirring speed is 100 r / min-300 r / min. Specifically, it can be any value between 100 r / min, 150 r / min, 200 r / min, 250 r / min, 300 r / min or 100 r / min-300 r / min. Stirring is beneficial to the uniform distribution of various ions in the solution. However, stirring too fast will affect the morphology of the precursor particles, and thus affect the performance of the cathode material.

[0066] In some embodiments, the washing step includes sequential water washing, ammonium bicarbonate solution washing, and water washing. Ammonium bicarbonate is alkaline, which can remove sulfur impurities, and the ammonium ion cation is easily removed, while the bicarbonate anion does not introduce new impurities. The water washing before the ammonium bicarbonate solution washing mainly removes copper on the particle surface, preventing the surface copper from reacting with ammonium bicarbonate and affecting the composition and surface morphology of the precursor. The water washing after the ammonium bicarbonate solution washing removes free ions mixed in the precursor.

[0067] In some embodiments, the temperature of the washing liquid in the washing step is 30℃-80℃, specifically any value between 30℃, 40℃, 50℃, 60℃, 70℃, 80℃ or 30℃-80℃, and hot water washing is more effective than cold water.

[0068] In some embodiments, the ammonium salt concentration in the ammonium bicarbonate solution is 0.2 mol / L-1.0 mol / L, and the amount of ammonium bicarbonate used is 10%-40% of the mass of the solid phase to be washed, specifically any value between 10%, 15%, 20%, 25%, 30%, 35%, 40%, or 10%-40%.

[0069] In some embodiments, the solid is dried after the washing step at a temperature of 80°C-120°C, specifically any value between 80°C, 90°C, 100°C, 110°C, 120°C, or 80°C-120°C, for a time of 24h-48h, specifically any value between 24h, 30h, 36h, 42h, 48h, or 24h-48h, until the sample moisture content is below 2wt%.

[0070] Secondly, this disclosure provides a nickel-manganese-copper-iron carbonate precursor obtained by the method described in any one of the foregoing embodiments, with the general formula Ni x Mn y Cu z Fe 1-x-y-z CO3, where 0≤x≤0.30, 0.30<y≤0.70, and 0<z≤0.30.

[0071] Thirdly, this disclosure provides the application of a nickel-manganese-copper-iron carbonate precursor obtained by any of the foregoing embodiments in the preparation of cathode materials for ion batteries.

[0072] The features and performance of this disclosure will be further described in detail below with reference to embodiments.

[0073] Example 1

[0074] The chemical composition of the nickel-manganese-copper-iron precursor described in this embodiment is Ni. 0.15 Mn 0.60 Cu 0.15 Fe 0.1 The synthesis of CO3 includes the following specific steps:

[0075] (1) Preparation of metal solution and precipitant solution:

[0076] Add pure water, soluble metal salts, and the complexing agent sodium citrate to a metal preparation container, and stir until completely dissolved. All metal salts are sulfates, namely nickel sulfate, manganese sulfate, ferrous sulfate, and copper sulfate. The molar ratio of nickel sulfate, manganese sulfate, ferrous sulfate, and copper sulfate is equal to the molar ratio of Ni, Mn, Cu, and Fe elements in the precursor. The total concentration of the metal salts is 2.0 mol / L. The molar ratio of sodium citrate to the total metal salts is 0.03:1. The concentration of the sodium carbonate solution is 1.8 mol / L.

[0077] (2) Preparation of the base solution: Add 3L of pure water to a 10L reactor, add 0.3mol sodium carbonate and 0.07mol sodium citrate, start stirring, the speed is 400r / min, and the temperature is raised to 50℃.

[0078] (3) Reaction: A metal salt solution and a precipitant solution were added to the reactor in parallel flow. The flow rate of the metal solution was 300 mL / h, and the molar ratio of sodium carbonate to the metal element was 1.4:1 with a flow rate of 467 mL / h. When the volume of the solution in the reactor reached the 10 L mark, a filter rod was used to purge the solution and maintain a constant liquid level. The reaction time was 24 h. During the reaction, the pH was controlled between 8.0 and 9.0 by controlling the flow rate of sodium carbonate. After the solution was added, the mixture was aged for 3 h.

[0079] (4) Post-treatment: Take 2L of slurry and filter it. Wash with water until the particle surface is neutral. Add the filter cake to a 0.005mol / L CuSO4 solution and soak and stir at a solution temperature of 50℃ and a stirring speed of 200r / min for 2h. Then filter again, rinse with hot water to remove residual Cu from the particle surface; rinse with a 0.5mol / L ammonium bicarbonate solution (ammonium bicarbonate amount is 20% of the sample mass); rinse with hot water. After washing, dry the filter cake in a forced-air drying oven at 120℃ for 24h until the sample moisture content is less than 2%.

[0080] (5) The dried filter cake is sieved to obtain the nickel-manganese-copper-iron carbonate precursor.

[0081] Example 2:

[0082] The chemical composition of the nickel-manganese-copper-iron precursor described in this embodiment is Ni. 0.15 Mn 0.60 Cu 0.15 Fe 0.1 The synthesis of CO3 includes the following specific steps:

[0083] (1) Preparation of metal solution and precipitant solution:

[0084] Add pure water, soluble metal salts, and the complexing agent sodium citrate to a metal preparation container, and stir until completely dissolved. All metal salts are sulfates, namely nickel sulfate, manganese sulfate, ferrous sulfate, and copper sulfate. The molar ratio of nickel sulfate, manganese sulfate, ferrous sulfate, and copper sulfate is equal to the molar ratio of Ni, Mn, Cu, and Fe in the precursor. The total concentration of the metal salts is 2.0 mol / L. The molar ratio of sodium citrate to the metal salts is 0.01:1. The sodium oxalate solution is prepared separately, with a concentration of 0.2 mol / L. The concentration of the sodium carbonate solution is 1.8 mol / L.

[0085] (2) Preparation of the base solution: Add 3L of pure water to a 10L reactor, add 0.3mol sodium carbonate, 0.02mol sodium citrate and 0.1mol sodium oxalate, start stirring at 400r / min, and heat to 50℃.

[0086] (3) Reaction: A metal salt solution, a precipitant solution, and a sodium oxalate solution were added to the reactor in parallel flow. The flow rate of the metal solution was 300 mL / h; the molar ratio of sodium carbonate to the metal element was 1.4:1, and the flow rate was 467 mL / h; the flow rate of the sodium oxalate solution was 150 mL / h, and the molar ratio of sodium oxalate to the metal salt was 0.05:1. When the volume of the solution in the reactor reached the 10 L mark, a filter rod was used to purge the solution and maintain a constant liquid level. The reaction time was 24 h. During the reaction, the pH was controlled between 8.0 and 9.0 by controlling the flow rate of sodium carbonate. After the initial addition of the solution, the mixture was aged for 3 h.

[0087] (4) Post-treatment: Take 2L of slurry and filter it. Wash with water until the particle surface is neutral. Add the filter cake to a 0.005mol / L CuSO4 solution and soak and stir at a solution temperature of 50℃ and a stirring speed of 200r / min for 2h. Then filter again, rinse with hot water to remove residual Cu from the particle surface; rinse with a 0.5mol / L ammonium bicarbonate solution (ammonium bicarbonate amount is 20% of the sample mass); rinse with hot water. After washing, dry the filter cake in a forced-air drying oven at 120℃ for 24h until the sample moisture content is less than 2%.

[0088] (5) The dried filter cake is sieved to obtain the nickel-manganese-copper-iron carbonate precursor.

[0089] Example 3:

[0090] The chemical composition of the nickel-manganese-copper-iron precursor described in this embodiment is Ni. 0.15 Mn 0.60 Cu 0.15 Fe 0.1 The synthesis of CO3 includes the following specific steps:

[0091] (1) Preparation of metal solution and precipitant solution:

[0092] Add pure water and soluble metal salts to the metal preparation container and stir until completely dissolved. All metal salts are sulfates, namely nickel sulfate, manganese sulfate, ferrous sulfate, and copper sulfate. The molar ratio of nickel sulfate, manganese sulfate, ferrous sulfate, and copper sulfate is equal to the molar ratio of Ni, Mn, Cu, and Fe in the precursor. The total concentration of the metal salts is 2.0 mol / L. The complexing agent, sodium oxalate solution, is prepared separately with a concentration of 0.2 mol / L. The concentration of the sodium carbonate solution is 1.8 mol / L.

[0093] (2) Preparation of the base solution: Add 3L of pure water to a 10L reactor, add 0.3mol of sodium carbonate and 0.17mol of sodium oxalate, start stirring, the speed is 400r / min, and the temperature is raised to 50℃.

[0094] (3) Reaction: A metal salt solution, a precipitant solution, and a sodium oxalate solution were added to the reactor in parallel flow. The flow rate of the metal solution was 300 mL / h; the molar ratio of sodium carbonate to the metal element was 1.4:1, and the flow rate was 467 mL / h; the flow rate of the sodium oxalate solution was 300 mL / h, and the molar ratio of sodium oxalate to the metal salt was 0.1:1. When the volume of the solution in the reactor reached the 10 L mark, a filter rod was used to purge the solution and maintain a constant liquid level. The reaction time was 24 h. During the reaction, the pH was controlled between 8.0 and 9.0 by controlling the flow rate of sodium carbonate. After the initial addition of the solution, the mixture was aged for 3 h.

[0095] (4) Post-treatment: Take 2L of slurry and filter it. Wash with water until the particle surface is neutral. Add the filter cake to a 0.005mol / L CuSO4 solution and soak and stir at a solution temperature of 50℃ and a stirring speed of 200r / min for 2h. Then filter again, rinse with hot water to remove residual Cu from the particle surface; rinse with a 0.5mol / L ammonium bicarbonate solution (ammonium bicarbonate amount is 20% of the sample mass); rinse with hot water. After washing, dry the filter cake in a forced-air drying oven at 120℃ for 24h until the sample moisture content is less than 2%.

[0096] (5) The dried filter cake is sieved to obtain the nickel-manganese-copper-iron carbonate precursor.

[0097] Example 4:

[0098] The chemical composition of the nickel-manganese-copper-iron precursor described in this comparative example is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1The difference between the synthesis method of CO3 and Example 1 is that the molar ratio of sodium citrate to metal salt in step (1) is 0.01:1, and the amount of sodium citrate added to the bottom solution is 0.023 mol.

[0099] Example 5:

[0100] The chemical composition of the nickel-manganese-copper-iron precursor described in this comparative example is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1 The difference between the synthesis method of CO3 and Example 1 is that the molar ratio of sodium citrate to metal salt in step (1) is 0.1:1, and the amount of sodium citrate added to the bottom solution is 0.234 mol.

[0101] Example 6:

[0102] The chemical composition of the nickel-manganese-copper-iron precursor described in this comparative example is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1 The difference between the CO3 synthesis method and Example 1 is that in step (4), the filter cake is soaked and stirred in a CuSO4 solution with a concentration of 0.01 mol / L.

[0103] Example 7:

[0104] The chemical composition of the nickel-manganese-copper-iron precursor described in this comparative example is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1 The difference between the CO3 synthesis method and Example 1 is that in step (4), the filter cake is soaked and stirred in a CuSO4 solution with a concentration of 0.001 mol / L.

[0105] Example 8:

[0106] The chemical composition of the nickel-manganese-copper-iron precursor described in this embodiment is Ni. 0.15 Mn 0.60 Cu 0.15 Fe 0.1 The synthesis of CO3 includes the following specific steps:

[0107] (1) Preparation of metal solution and precipitant solution:

[0108] Add pure water, soluble metal salts, and the complexing agent sodium citrate to a metal preparation container, and stir until completely dissolved. All metal salts are sulfates, namely nickel sulfate, manganese sulfate, ferrous sulfate, and copper sulfate. The molar ratio of nickel sulfate, manganese sulfate, ferrous sulfate, and copper sulfate is equal to the molar ratio of Ni, Mn, Cu, and Fe elements in the precursor. The total concentration of the metal salts is 1.0 mol / L. The molar ratio of sodium citrate to the metal salts is 0.2:1. The concentration of the sodium carbonate solution is 1.8 mol / L.

[0109] (2) Preparation of the base solution: Add 3L of pure water to a 10L reactor, add 1.5mol sodium carbonate and 0.28mol sodium citrate, start stirring, the speed is 400r / min, and the temperature is raised to 80℃.

[0110] (3) Reaction: A metal salt solution and a precipitant solution were added to the reactor in parallel flow. The flow rate of the metal solution was 300 mL / h, and the molar ratio of sodium carbonate to the metal element was 2.0:1 with a flow rate of 334 mL / h. When the solution volume in the reactor reached the 10 L mark, a filter rod was used to purge the solution and maintain a constant liquid level. The reaction time was 48 h. During the reaction, the pH was controlled between 10.0 and 11.0 by controlling the flow rate of sodium carbonate. After the solution was added, the reactor was aged for 24 h.

[0111] (4) Post-treatment: Take 2L of slurry and filter it. Wash it with water until the particle surface is neutral. Add the filter cake to a 0.05mol / L CuSO4 solution and soak and stir at 80℃. The stirring speed is 200r / min and the soaking time is 2h. Then filter it again, rinse with hot water to remove residual Cu from the particle surface, rinse with ammonium bicarbonate solution (0.5mol / L ammonium bicarbonate, 20% of the sample mass), rinse with hot water, and after washing, dry the filter cake in a forced-air drying oven at 120℃ for 24h until the sample moisture content is less than 2%.

[0112] (5) The dried filter cake is sieved to obtain the nickel-manganese-copper-iron carbonate precursor.

[0113] Example 9:

[0114] The chemical composition of the nickel-manganese-copper-iron precursor described in this embodiment is Ni. 0.15 Mn 0.60 Cu 0.15 Fe 0.1 The synthesis of CO3 includes the following specific steps:

[0115] (1) Preparation of metal solution and precipitant solution:

[0116] Add pure water, soluble metal salts, and the complexing agent sodium citrate to a metal preparation container, and stir until completely dissolved. All metal salts are sulfates, namely nickel sulfate, manganese sulfate, ferrous sulfate, and copper sulfate. The molar ratio of nickel sulfate, manganese sulfate, ferrous sulfate, and copper sulfate is equal to the molar ratio of Ni, Mn, Cu, and Fe elements in the precursor. The total concentration of the metal salts is 1.5 mol / L. The molar ratio of sodium citrate to the metal salts is 0.005:1. The concentration of the sodium carbonate solution is 1.0 mol / L.

[0117] (2) Preparation of the base solution: Add 3L of pure water to a 10L reactor, add 0.03mol sodium carbonate and 0.007mol sodium citrate, start stirring, the speed is 400r / min, and the temperature is raised to 30℃.

[0118] (3) Reaction: A metal salt solution and a precipitant solution were added to the reactor in parallel flow. The flow rate of the metal solution was 200 mL / h, and the molar ratio of sodium carbonate to the metal element was 1.2:1 with a flow rate of 500 mL / h. When the volume of the solution in the reactor reached the 10 L mark, a filter rod was used to purge the solution and maintain a constant liquid level. The reaction time was 12 h. During the reaction, the pH was controlled between 8.0 and 9.0 by controlling the flow rate of sodium carbonate. After the solution was added, the mixture was aged for 1 h.

[0119] (4) Post-treatment: Take 2L of slurry and filter it. Wash with water until the particle surface is neutral. Add the filter cake to a 0.001mol / L CuSO4 solution and soak and stir at 30℃. The stirring speed is 100r / min and the soaking time is 2h. Then filter again, rinse with hot water to remove residual Cu from the particle surface; rinse with ammonium bicarbonate solution (0.5mol / L ammonium bicarbonate, 20% of the sample mass); rinse with hot water. After washing, dry the filter cake in a forced-air drying oven at 120℃ for 24h until the sample moisture content is less than 2%.

[0120] (5) The dried filter cake is sieved to obtain the nickel-manganese-copper-iron carbonate precursor.

[0121] Example 10:

[0122] This comparative example adjusts the amounts of sulfates, namely nickel sulfate, manganese sulfate, ferrous sulfate, and copper sulfate, so that the chemical composition of the nickel-manganese-copper-iron precursor is Ni. 0.10 Mn 0.70 Cu 0.10 Fe 0.1 CO3, and the other steps are the same as in Example 1.

[0123] Comparative Example 1:

[0124] The chemical composition of the nickel-manganese-copper-iron precursor described in this comparative example is Ni 0.15Mn 0.60 Cu 0.15 Fe 0.1 The CO3 synthesis method differs from that in Example 1 in that no complexing agent was added, and no CuSO4 solution was added for soaking and stirring. The specific steps include the following:

[0125] (1) Preparation of metal solution and precipitant solution:

[0126] Add pure water and soluble metal salts to the metal preparation container and stir until completely dissolved. All metal salts are sulfates, namely nickel sulfate, manganese sulfate, ferrous sulfate, and copper sulfate. The molar ratio of nickel sulfate, manganese sulfate, ferrous sulfate, and copper sulfate is equal to the molar ratio of Ni, Mn, Cu, and Fe elements in the precursor. The total concentration of the metal salts is 2.0 mol / L, and the concentration of the sodium carbonate solution is 1.8 mol / L.

[0127] (2) Preparation of the base solution: Add 3L of pure water and 0.3mol of sodium carbonate to a 10L reactor, start stirring at 400r / min, and heat to 50℃.

[0128] (3) Reaction: A metal salt solution and a precipitant solution were added to the reactor in parallel flow. The flow rate of the metal solution was 300 mL / h, and the molar ratio of sodium carbonate to the metal element was 1.4:1 with a flow rate of 467 mL / h. When the volume of the solution in the reactor reached the 10 L mark, a filter rod was used to purge the solution and maintain a constant liquid level. The reaction time was 24 h. During the reaction, the pH was controlled between 8.0 and 9.0 by controlling the flow rate of sodium carbonate. After the solution was added, the mixture was aged for 3 h.

[0129] (4) Post-processing: Take 2L of slurry for filtration, rinse with ammonium bicarbonate solution, the amount of 0.5mol / L ammonium bicarbonate used is 20% of the sample mass; rinse with hot water, and after washing, dry the filter cake in a forced-air drying oven at 120℃ for 24 hours until the moisture content of the sample is less than 2%.

[0130] (5) The dried filter cake is sieved to obtain the nickel-manganese-copper-iron carbonate precursor.

[0131] Comparative Example 2:

[0132] The chemical composition of the nickel-manganese-copper-iron precursor described in this comparative example is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1 The difference between the CO3 synthesis method and Example 1 is that a complexing agent is added and hot water is used instead of copper sulfate solution.

[0133] Comparative Example 3:

[0134] The chemical composition of the nickel-manganese-copper-iron precursor described in this comparative example is Ni0.15 Mn 0.60 Cu 0.15 Fe 0.1 The CO3 synthesis method differs from that in Example 1 in that no complexing agent was added.

[0135] Comparative Example 4:

[0136] The chemical composition of the nickel-manganese-copper-iron precursor described in this comparative example is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1 The difference between the CO3 synthesis method and Example 3 is that sodium oxalate is replaced with ammonia water, the concentration of ammonia water is 80 g / L, and the concentration of ammonia water is controlled to 2 g / L during the reaction process by testing.

[0137] The elemental content of the precursors obtained in each embodiment and comparative example was detected. The precursors were also prepared into cathode materials and tested. The results are shown in the table below.

[0138]

[0139]

[0140] from Figure 2-5 It can be seen that adding a suitable complexing agent (at least one of sodium citrate, citric acid, sodium oxalate, and EDTA) can reduce Ni 2+ Mn 2+ Fe 2+ Cu 2+ Four ions co-precipitated, and there was no segregation on the surface of the sample particles. However, ammonia water, as a complexing agent, would exacerbate the segregation of Mn elements, forming individual blocky particles.

[0141] As can be seen from Table 1, the element content of the examples is within the error range of the target values, and the contents of Na and S are both below 2000 ppm, indicating that the batch stability of the examples is significantly improved.

[0142] As shown in Table 1, the cathode materials prepared in the examples and comparative examples exhibited initial discharge capacities ranging from 132 to 156 mAh / g in the 0.1C charge-discharge performance test. Among them, the active material obtained in Example 2 showed the highest initial discharge specific capacity and the highest capacity retention rate after 100 cycles at 0.5C, demonstrating the best performance. Therefore, the nickel-manganese-copper-iron precursor samples prepared by adding a complexing agent, strictly controlling the reaction conditions, and using a copper salt solution soaking and stirring process can effectively improve the capacity and cycle performance of the cathode material, thereby enhancing its electrochemical performance.

[0143] The preparation of the cathode material tested in the table above includes: First, the carbonate precursors obtained in the examples and comparative examples are placed in a muffle furnace and calcined at 500°C for 6 hours, then cooled. Then, the sintered precursor material and Na2CO3 are mixed in a plowshare mixer at a molar ratio of 1.0:1.05, and then placed in a muffle furnace and calcined at 850°C for 12 hours, then cooled to obtain the cathode material.

[0144] Preparation of the positive electrode for testing: The positive electrode material was mixed with conductive carbon black and polyvinylidene fluoride at a mass ratio of 8:1:1. An appropriate amount of N-methylpyrrolidone was added and the mixture was homogenized in a high-speed homogenizer to obtain the positive electrode slurry. The positive electrode slurry was then coated on a clean aluminum foil and dried in an 80°C vacuum drying oven for 12 hours to prepare the positive electrode for testing.

[0145] Charge-discharge test: In a glove box, a 2032 coin cell was assembled using a sodium sheet as the negative electrode and subjected to charge-discharge tests. Its charge-discharge performance was measured at 0.1C, and its cycle retention rate after 100 cycles at 0.5C was also measured. The test voltage window was 1.5–4.2V, and the test temperature was 25℃. The test results are detailed in the table above.

[0146] Industrial applicability

[0147] This disclosure enables the realization of Ni 2+ Mn 2+ Fe 2+ Cu 2+ The complexation of the four metal ions allows them to be slowly released under the action of the precipitant, achieving co-precipitation of the four metal ions. This results in a uniform precursor morphology without segregation. Furthermore, by adjusting the co-precipitation and aging time as well as the concentration of each reagent, the particle size can be effectively controlled, thereby improving the sphericity of the precursor particles in the later stages of formation.

[0148] This disclosure describes a post-treatment step for the precipitated product, in which the precipitated product is soaked in an aqueous solution of copper salt to allow Cu to... 2+ With residual CO3 in the particles 2- Combined, this supplements the Cu content in the precursor material.

[0149] This disclosure discloses a post-treatment step for the precipitated product, in which the precipitated product is soaked in an aqueous solution of copper salt to dissolve impurities such as sodium and sulfur in the precipitated product, thereby reducing the content of impurities such as sodium and sulfur in the precursor and improving the batch stability and overall performance of the precursor material.

Claims

1. A method for preparing a nickel-manganese-copper-iron carbonate precursor, characterized in that The method comprises the following steps: Co-precipitation: gradually adding a metal ion solution containing Ni 2+ , Mn 2+ , Fe 2+ , Cu 2+ four metal ions, a complexing agent solution and a sodium carbonate solution into a base solution containing sodium carbonate and a complexing agent, maintaining the pH of the reaction solution between 8.0-11.0, co-precipitating and aging, and performing solid-liquid separation on the post-reaction solution to obtain carbonate particles; the complexing agent is at least one of sodium citrate, citric acid, sodium oxalate and EDTA; the ratio of the molar amount of the complexing agent in the complexing agent solution to the total molar amount of Ni 2+ , Mn 2 + , Fe 2+ , Cu 2+ four metal ions in the metal ion solution is (0.005-0.2):1; Post-treatment: the carbonate particles, which are washed to be neutral to the surface of the particles, are soaked in an aqueous solution of copper salt, then solid-liquid separation is performed and the solid phase is washed to obtain a nickel-manganese-copper-iron carbonate precursor, the concentration of the copper salt in the aqueous solution of the copper salt is 0.001 mol / L-0.05 mol / L, and the total molar amount of the copper salt in the aqueous solution of the copper salt is (z-z0)n / K, unit: mol; wherein z is the coefficient of copper in the target precursor; z0 is the coefficient of copper in the carbonate particles; n is the molar amount of the carbonate particles soaked in the aqueous solution of the copper salt, unit: mol; and K is a constant and K∈(0.6-0.8).

2. The method for preparing the nickel-manganese-copper-iron carbonate precursor according to claim 1, characterized in that, The concentration of sodium carbonate in the bottom solution is 0.01 mol / L-0.5 mol / L.

3. The method for preparing the nickel-manganese-copper-iron carbonate precursor according to claim 1, characterized in that, The concentration of the complexing agent in the bottom solution is equal to the concentration of the complexing agent in the reaction solution.

4. The method for preparing the nickel-manganese-copper-iron carbonate precursor according to claim 1, characterized in that, The total concentration of the four metal ions in the metal ion solution is 1.0 mol / L-2.0 mol / L, and the metal ion solution is a sulfate solution of the metals. 2+ , Mn 2+ , Fe 2+ , Cu 2+ ​ 5. The method for preparing the nickel-manganese-copper-iron carbonate precursor according to claim 1, characterized in that, The ratio of the total moles of the four metal ions to the moles of sodium carbonate added to the base solution is (1.2-2.0):

1. 2+ , Mn 2+ , Fe 2+ , Cu 2+ The ratio of the total moles of the four metal ions to the moles of sodium carbonate added to the base solution is (1.2-2.0):

1.

6. The method for preparing the nickel-manganese-copper-iron carbonate precursor according to claim 1, characterized in that, The concentration of sodium carbonate in the sodium carbonate solution is 1.0 mol / L-1.8 mol / L.

7. The method for preparing the nickel-manganese-copper-iron carbonate precursor according to claim 1, characterized in that, The temperature of the co-precipitation step is 30°C-80°C, and the time is 12 h-48 h.

8. The method of claim 1, wherein the nickel-manganese-copper-iron carbonate precursor is prepared by the steps of: The temperature of the aging step is 30°C-80°C, and the time is 0 h-24 h. ​ 9. The method for preparing the nickel-manganese-copper-iron carbonate precursor according to claim 1, characterized in that, After the metal ion solution, the complexing agent solution and the sodium carbonate solution are added to the bottom solution until the volume ratio of the reaction solution to the bottom solution is 2-0.5:1, the filter rod is used to draw clear or the concentration machine is used for concentration, and the volume ratio of the reaction solution to the bottom solution is maintained at 2-0.5:

1.

10. The method of claim 9, wherein the nickel-manganese-copper-iron carbonate precursor is prepared by the steps of: The flow rate of the metal ion solution is 0.05 L / h-0.2 L / h per liter of the bottom solution. ​ 11. The method of claim 1, wherein the nickel-manganese-copper-iron carbonate precursor is prepared by the steps of: The copper salt is copper sulfate or copper nitrate. ​ 12. The method of claim 1, wherein the nickel-manganese-copper-iron carbonate precursor is prepared by the steps of: The soaking step is accompanied by stirring, and the stirring speed is 100 r / min-300 r / min. ​ 13. The method for preparing the nickel-manganese-copper-iron carbonate precursor according to claim 1, characterized in that, The washing step comprises water washing, ammonium bicarbonate solution washing and water washing in sequence.

14. The method of claim 1, wherein the nickel manganese copper iron carbonate precursor is prepared by the steps of: The temperature of the washing solution in the washing step is 30°C-80°C. ​ 15. The method of claim 14, wherein the nickel manganese copper iron carbonate precursor is prepared by the steps of: The concentration of the ammonium salt in the ammonium bicarbonate solution is 0.2 mol / L-1.0 mol / L, and the amount of ammonium bicarbonate is 10%-40% of the mass of the solid phase to be washed. ​ 16. The method of claim 14, wherein the nickel manganese copper iron carbonate precursor is prepared by the steps of: After the washing step, the solid is dried, the drying temperature is 80°C-120°C, the time is 24 h-48 h, and the sample moisture content is less than 2 wt%. ​ 17. The method of producing a nickel manganese copper iron carbonate precursor according to any one of claims 1 to 16, characterized in that, 19. Use of a nickel-manganese-copper-iron carbonate precursor obtained by the method of any one of claims 1-17 in the preparation of a sodium-ion battery positive electrode material.

18. A nickel manganese copper iron carbonate precursor obtained by the method of any one of claims 1 to 17, characterized in that, Ni x Mn y Cu z Fe 1-x-y-z CO3, wherein 0≤x≤0.30, 0.30 y≤0.70, 0 z≤0.

30. ​

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