Nickel-manganese-copper-iron carbonate precursor, preparation method, and use in preparation of sodium-ion battery positive electrode material

Abstract

Disclosed in the present disclosure are a nickel-manganese-copper-iron carbonate precursor, a preparation method, and the use in the preparation of a sodium-ion battery positive electrode material. Four metal ions of Ni2+, Mn2+, Fe2+ and Cu2+ can be complexed, and the metal ions are slowly released under the action of a precipitator, thereby co-precipitating the four metal ions, such that the prepared precursor is uniform in terms of morphology and segregation does not occur. Impurities such as sodium and sulfur in the precipitated product can be reduced by means of performing a post-treatment on the product, and the content of copper in the precursor can also be increased.

Description

Nickel manganese copper iron carbonate precursor, preparation method and application in preparing positive electrode material for sodium ion battery Technical Field

[0001] The present disclosure relates to the technical field of sodium ion battery positive electrode materials, and in particular to a nickel manganese copper iron carbonate precursor, a preparation method and an application in preparing sodium ion battery positive electrode materials. Background Art

[0002] Currently, lithium-ion batteries are the leading candidate for energy storage systems. Their introduction into the automotive market as the battery of choice for hybrid, plug-in hybrid, and electric vehicles (HEVs) can reduce reliance on fossil fuels. With the widespread adoption of lithium-ion batteries, demand for lithium continues to increase, and it is estimated that currently recoverable lithium resources will 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. The sodium-ion cathode material prepared using layered nickel-manganese-copper-iron precursors has great development prospects. It has the advantages of a wide range of raw material sources, low cost, excellent cycle performance, and high safety. The co-precipitation method for preparing precursors has the advantages of simple operation, easy morphology control, and low cost. However, the nickel-manganese-copper-iron quaternary carbonate system has a large difference in the precipitation coefficients of the four carbonates, and Fe 2+ 、Cu 2+ With CO3 2- Reactions in solution can generate a variety of products. The complex reaction process prevents the four metal ions from co-precipitating, and a large amount of segregation occurs in the particles. In addition, there are problems in the precursor preparation process such as a low precipitation rate of the Cu element during the reaction, and a high residual Na content in the particles after the post-treatment process. The segregation of elements in the precursor material will be transferred to the positive electrode material, which will cause major problems for sodium-ion batteries, such as low capacity and poor cycle performance. The low element precipitation rate causes the element ratio of the precursor and the positive electrode material to deviate from the target value. The high residual Na content in the particles requires adjustment of the Na to precursor ratio in the subsequent preparation of the positive electrode material, affecting the batch stability of the material.

[0004] Based on the above research, it is necessary to develop a method to synthesize nickel-manganese-copper-iron quaternary carbonate precursor with uniform morphology, element ratios meeting the set value, and low residual Na content, so as to improve the electrochemical performance and batch stability of the positive electrode material.

[0005] In view of this, the present disclosure is proposed.

[0006] Summary of the Invention

[0007] 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 sodium ion battery positive electrode materials, to achieve Ni 2+ 、Mn 2+ 、Fe 2+ 、Cu 2+ The four metal ions are precipitated simultaneously, and the ratio of each element in the precursor deviates from the target value slightly, which is beneficial to the control of the performance of the positive electrode material.

[0008] The present disclosure is achieved as follows:

[0009] In a first aspect, the present disclosure provides a method for preparing a nickel-manganese-copper-iron carbonate precursor, comprising:

[0010] Co-precipitation: gradually add Ni into the base solution containing sodium carbonate and complexing agent. 2+ 、Mn 2+ 、Fe 2+ 、Cu 2+ A metal ion solution of four metal ions, a complexing agent solution, and a sodium carbonate solution are prepared, the pH of the reaction solution is maintained between 8.0 and 11.0, coprecipitation and aging are performed, and the reaction solution is 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;

[0011] Post-treatment: The carbonate particles washed with water until the particle surface is neutral are immersed in an aqueous solution of copper salt, and then solid-liquid separation is performed and the solid phase is washed to obtain a nickel-manganese-copper-iron carbonate precursor.

[0012] In some embodiments, the concentration of sodium carbonate in the base solution is 0.01 mol / L-0.5 mol / L.

[0013] 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.

[0014] In some embodiments, the metal ion solution contains Ni 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.

[0015] In some embodiments, the molar amount of the complexing agent in the complexing agent solution is equal to the molar amount of Ni in the metal ion solution. 2+ 、Mn 2+ 、Fe 2+ 、Cu 2+ The total molar ratio of the four metal ions is (0.005-0.2):1.

[0016] In some embodiments, the molar amount of sodium carbonate added to the bottom solution is equal to the molar 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.

[0017] In some embodiments, the concentration of sodium carbonate in the sodium carbonate solution is 1.0 mol / L-1.8 mol / L.

[0018] In some embodiments, the co-precipitation step is performed at a temperature of 30° C. to 80° C. and for a time of 12 h to 48 h.

[0019] In some embodiments, the aging step is performed at a temperature of 30° C. to 80° C. and for a time of 0 h to 24 h.

[0020] In some embodiments, metal ion solution, complexing agent solution and sodium carbonate solution are added to the base liquid until the volume of the reaction liquid is 2-0.5:1 to the volume of the base liquid, and then the solution is pumped out using a filter rod or concentrated using a concentrator to maintain the ratio of the volume of the reaction liquid to the volume of the base liquid at 2-0.5:1.

[0021] In some embodiments, the flow acceleration of the metal ion solution is 0.05 L / h-0.2 L / h per liter of base liquid.

[0022] In some embodiments, the copper salt is copper sulfate or copper nitrate, and the concentration of the copper salt in the aqueous solution of the copper salt is 0.001 mol / L-0.05 mol / L.

[0023] In some embodiments, the total molar amount of copper salt in the aqueous solution of copper salt is (z-z0)n / K, in 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 carbonate particles immersed in the aqueous solution of copper salt, in mol; K is a constant and K∈(0.6-0.8).

[0024] In some embodiments, the soaking step is performed for 1 hour to 24 hours at a temperature of 30°C to 80°C.

[0025] In some embodiments, the soaking step is accompanied by stirring, and the stirring speed is 100 r / min-300 r / min.

[0026] In some embodiments, the washing step comprises sequentially washing with water, washing with ammonium bicarbonate solution, and washing with water.

[0027] In some embodiments, the temperature of the washing solution in the washing step is 30°C-80°C.

[0028] 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.

[0029] In some embodiments, the solid is dried after the washing step, and the drying temperature is 80° C.-120° C., and the drying time is 24 h-48 h, until the moisture content of the sample is less than 2 wt %.

[0030] In the second aspect, the present disclosure provides a nickel manganese copper iron carbonate precursor obtained by the method described in any one of the aforementioned embodiments, the general formula is Ni x Mn y Cu z Fe 1-x-y-z CO3, where 0≤x≤0.30, 0.30<y≤0.70, 0<z≤0.30.

[0031] In a third aspect, the present disclosure provides an application of a nickel manganese copper iron carbonate precursor obtained by the method described in any one of the aforementioned embodiments in the preparation of positive electrode materials for ion batteries.

[0032] The present disclosure has the following beneficial effects:

[0033] The present disclosure can realize Ni 2+ 、Mn 2+ 、Fe 2+ 、Cu 2+ The four metal ions are complexed and slowly released under the action of the precipitant, achieving co-precipitation of the four metal ions, making the prepared precursor morphology uniform and without segregation. The particle size can also 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 forming process.

[0034] The present invention discloses a post-processing step for the precipitation product, wherein the precipitation product is placed in an aqueous solution of copper salt for soaking, so that Cu 2+ and the residual CO3 in the particles 2- Combined with, supplement the content of Cu element in the precursor material.

[0035] The present disclosure implements a post-processing step for the precipitation product, wherein the precipitation product is immersed in an aqueous solution of copper salt to dissolve the impurity elements in the precipitation product, thereby reducing the impurity content in the precursor, which is beneficial to improving the batch stability and comprehensive performance of the precursor material. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0037] FIG1 is a flow chart of a method for preparing a nickel manganese copper iron carbonate precursor disclosed herein;

[0038] FIG2 is a SEM image of the precursor obtained in Example 1;

[0039] FIG3 is a SEM image of the precursor obtained in Example 2;

[0040] FIG4 is a SEM image of the precursor obtained in Comparative Example 1;

[0041] FIG5 is a SEM image of the precursor obtained in Comparative Example 2. DETAILED DESCRIPTION

[0042] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer were followed. Reagents or instruments used where the manufacturer is not specified are conventional products that can be purchased commercially.

[0043] In a first aspect, the present disclosure provides a method for preparing a nickel-manganese-copper-iron carbonate precursor, as shown in FIG1 , comprising:

[0044] Co-precipitation: gradually add Ni into the base solution containing sodium carbonate and complexing agent. 2+ 、Mn 2+ 、Fe 2+ 、Cu 2+ A metal ion solution of four metal ions, a complexing agent solution, and a sodium carbonate solution are prepared, the pH of the reaction solution is maintained between 8.0 and 11.0, coprecipitation and aging are performed, and the reaction solution is 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;

[0045] Post-treatment: The carbonate particles washed with water until the particle surface is neutral are immersed in an aqueous solution of copper salt, and then solid-liquid separation is performed and the solid phase is washed to obtain a nickel-manganese-copper-iron carbonate precursor.

[0046] The nickel-manganese-copper-iron quaternary carbonate system has a large difference in precipitation coefficients of the four carbonates, and Fe 2+ 、Cu 2+ With CO3 2-The reaction in solution can generate a variety of products. The complex reaction process makes it impossible for the four metal ions to co-precipitate, and the particles show a large amount of segregation. In the preparation of precursor materials, ammonia is often used as a complexing agent to make different metal ions co-precipitate, but Mn 2+ The coordination effect with NH3 is very poor. Applying ammonia water to the nickel-manganese-copper-iron quaternary carbonate coprecipitation process will aggravate the segregation of Mn elements and generate separate MnCO3 particles. Therefore, the present invention adjusts the amount of sodium carbonate in the base liquid and the type and amount of the complexing agent, and coordinates the amount of metal ions, complexing agent and sodium carbonate added to the base liquid to maintain the pH of the reaction solution between 8.0 and 11.0, specifically 8.0, 9.0, 10.0, 11.0 or any value between 8.0 and 11.0, which can achieve the effect of Ni 2+ 、Mn 2+ 、Fe 2+ 、Cu 2+ The four metal ions are complexed and slowly released under the action of the precipitant, achieving co-precipitation of the four metal ions, making the prepared precursor morphology uniform and without segregation. The particle size can also be effectively controlled by adjusting the co-precipitation and aging time as well as the concentration of each reagent, thereby improving the sphericity of the precursor particles in the later forming process.

[0047] Considering that there is still a problem in the precursor preparation process where the precipitation rate of Cu element is low during the reaction process, resulting in the element content of the sample particles being lower than expected, the present invention discloses a post-processing step for the precipitation product, wherein the precipitation product is placed in an aqueous solution of copper salt for soaking, so that Cu 2+ and the residual CO3 in the particles 2- Combined with, supplement the content of Cu element in the precursor material.

[0048] During the coprecipitation or aging step, the Na + 、SO4 2- 、CO3 2- will enter the sample particles, Na + 、SO4 2- The presence of has an adverse effect on the electrochemical properties of the precursor. Conventional washing processes use alkali washing to reduce the S content and water washing to remove Na in the sample. However, when the S content is reduced to about 1000 ppm during the carbonate washing process, the Na content is about 10000 ppm. The present invention discloses a post-processing step for the precipitated product, in which the precipitated product is immersed in an aqueous solution of copper salt to dissolve impurity elements such as sodium and sulfur in the precipitated product, thereby reducing the content of impurities such as sodium and sulfur in the precursor, which is beneficial to improving the batch stability and comprehensive performance of the precursor material.

[0049] In some embodiments, the concentration of sodium carbonate in the base solution is 0.01mol / L-0.5mol / L, specifically 0.01mol / L, 0.05mol / L, 0.1mol / L, 0.2mol / L, 0.3mol / L, 0.4mol / L, 0.5mol / L or any value between 0.01mol / L and 0.5mol / L. Sodium carbonate is used as a reactant to combine with metal ions to produce carbonate precipitation. On the other hand, the pH of the reaction solution can be adjusted to meet Ni 2+ 、Mn 2+ 、Fe 2+ 、Cu 2+ The need for co-precipitation of four metal ions.

[0050] 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; n1 is the molar amount of the complexing agent and the 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 molar amount of sodium carbonate added to the bottom solution and 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 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 other metal ions.

[0051] In some embodiments, the metal ion solution contains Ni 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 will affect the reaction rate. If the reaction rate is too fast, more impurities will be included in the precipitated product, making it difficult to control the morphology of the precursor, thereby affecting the electrochemical properties of the final positive electrode material.

[0052] During the coprecipitation or aging step, the Na + 、SO4 2- 、CO3 2- will enter the sample particles, Na + 、SO4 2- The presence of has an adverse effect on the electrochemical properties of the precursor. Conventional washing processes use alkali washing to reduce the S content and water washing to remove Na in the sample. However, when the S content is reduced to about 1000 ppm during the carbonate washing process, the Na content is about 10000 ppm. The present invention discloses a post-processing step for the precipitated product, in which the precipitated product is immersed in an aqueous solution of copper salt to dissolve impurity elements such as sodium and sulfur in the precipitated product, thereby reducing the content of impurities such as sodium and sulfur in the precursor, which is beneficial to improving the batch stability and comprehensive performance of the precursor material.

[0053] 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 according to 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.

[0054] In some embodiments, the molar amount of the complexing agent in the complexing agent solution is equal to the molar amount of Ni in the metal ion solution. 2+ 、Mn 2+ 、Fe 2+ 、Cu 2+The total molar ratio of the four metal ions is (0.005-0.2):1, specifically 0.005:1, 0.01:1, 0.1:1, 0.2:1 or any value between (0.005-0.2):1.

[0055] In some embodiments, the molar amount of sodium carbonate added to the bottom solution is equal to the molar 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, and specifically can be 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. Generally, the pH of the reaction solution can be maintained between 8.0 and 11.0 by adding sodium carbonate according to the above ratio. However, if the pH exceeds this range under certain reaction conditions, the pH can be adjusted by adding additional sodium carbonate solution.

[0056] In some embodiments, the concentration of sodium carbonate in the sodium carbonate solution is 1.0 mol / L-1.8 mol / L, specifically 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 any value between 1.0 mol / L and 1.8 mol / L to match the dosage of metal salt and complexing agent.

[0057] In some embodiments, the temperature of the co-precipitation step is 30°C-80°C, specifically 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or any value between 30°C and 80°C, and the time is 12h-48h, specifically 12h, 18h, 24h, 30h, 36h, 42h, 48h or any value between 12h and 48h.

[0058] In some embodiments, the temperature of the aging step is 30°C-80°C, specifically 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or any value between 30°C-80°C, and the time is 0h-24h, specifically 0h, 6h, 12h, 18h, 24h or any value between 0h-24h.

[0059] In some embodiments, the metal ion solution, the complexing agent solution, and the sodium carbonate solution are added to the base liquid until the volume of the reaction liquid is 2-0.5:1 to the volume of the base liquid, and then the solution is pumped out using a filter stick or concentrated in a concentrator to maintain the ratio of the volume of the reaction liquid to the volume of the base liquid at 2-0.5:1. Specifically, the ratio can be 2:1, 1.5:1, 1:1, 0.5:1, or any value between (2-0.5):1).

[0060] In the specific operation of some embodiments, the base liquid is first added to the reactor, and then the metal ion solution, the complexing agent solution and the sodium carbonate solution are added thereto. Since continuous stirring is required during the coprecipitation process, in order to ensure the stirring effect, the amount of the base liquid is usually greater than the stirring paddle in the reactor, and the volume of the base liquid is usually 1 / 3-2 / 3 of the volume of the reactor.

[0061] In some embodiments, the flow acceleration of the metal ion solution is 0.05 L / h-0.2 L / h per liter of the base solution; the flow acceleration of the complexing agent solution is c1v1n1 / c3, in L / h; the flow acceleration of the sodium carbonate solution is c1v1n2 / c2, in L / ; wherein c1 is the total concentration of the four metal ions in the metal ion solution, in mol / L; n1 is the molar amount of the complexing agent relative to the 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 molar amount of sodium carbonate added to the base solution and 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.

[0062] In some embodiments, the copper salt is copper sulfate or copper nitrate, and the concentration of the copper salt in the aqueous solution of the copper salt is 0.001 mol / L-0.05 mol / L, specifically 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 any value between 0.001 mol / L and 0.05 mol / L, which is conducive to the combination of copper ions with free carbonates in the precipitated product.

[0063] In some embodiments, the total molar amount of copper salt in the aqueous solution of copper salt is (z-z0)n / K, in 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 carbonate particles immersed in the aqueous solution of copper salt, in mol; K is a constant and K∈(0.6-0.8).

[0064] The copper in the copper salt solution cannot fully enter the carbonate particles. When the copper ion content in the target precursor differs significantly from that in the carbonate particles, the solution should contain more copper ions. Conversely, when the copper ion content in the target precursor differs slightly from that in the carbonate particles, the solution should not contain too many copper ions to avoid over- or under-replenishing copper. Specifically, K can be selected from 0.60, 0.65, 0.70, 0.75, 0.80, or any value between 0.6 and 0.8.

[0065] In some embodiments, the soaking step is performed for a time of 1 hour to 24 hours, specifically 1 hour, 6 hours, 12 hours, 18 hours, 24 hours or any value between 1 hour and 24 hours, and the temperature is 30°C to 80°C, specifically 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or any value between 30°C and 80°C. 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 replenishment effect; on the other hand, elements such as sodium and sulfur contained in the carbonate particles can also be fully dissolved, reducing the content of impurities in the precursor.

[0066] In some embodiments, the immersion step is accompanied by stirring, and the stirring speed is 100r / min-300r / min, specifically 100r / min, 150r / min, 200r / min, 250r / min, 300r / min or any value between 100r / min-300r / min. Stirring is beneficial to the uniform distribution of various ions in the solution, but stirring too fast will affect the morphology of the precursor particles, thereby affecting the performance of the positive electrode material.

[0067] In some embodiments, the washing step includes sequentially performing a water wash, an ammonium bicarbonate solution wash, and a water wash. The ammonium bicarbonate solution is alkaline and can remove sulfur impurities. The ammonium ion cation is easily removed, and the bicarbonate anion does not introduce new impurities. The water wash before the ammonium bicarbonate solution wash primarily removes copper on the particle surface, preventing the surface copper from reacting with the ammonium bicarbonate solution and affecting the composition and surface morphology of the precursor. The water wash after the ammonium bicarbonate solution wash removes free ions contained in the precursor.

[0068] In some embodiments, the temperature of the washing liquid in the washing step is 30°C-80°C, specifically 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or any value between 30°C-80°C. The washing effect of hot water is better than that of cold water.

[0069] 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 10%, 15%, 20%, 25%, 30%, 35%, 40% or any value between 10% and 40%.

[0070] In some embodiments, the solid is dried after the washing step, and the drying temperature is 80°C-120°C, specifically 80°C, 90°C, 100°C, 110°C, 120°C or any value between 80°C and 120°C, and the drying time is 24h-48h, specifically 24h, 30h, 36h, 42h, 48h or any value between 24h-48h, and the sample is dried until the moisture content is less than 2wt%.

[0071] In the second aspect, the present disclosure provides a nickel manganese copper iron carbonate precursor obtained by the method described in any one of the aforementioned embodiments, the general formula is Ni x Mn y Cu z Fe 1-x-y-z CO3, where 0≤x≤0.30, 0.30<y≤0.70, 0<z≤0.30.

[0072] In a third aspect, the present disclosure provides an application of a nickel manganese copper iron carbonate precursor obtained by the method described in any one of the aforementioned embodiments in the preparation of positive electrode materials for ion batteries.

[0073] The features and performance of the present disclosure are further described in detail below with reference to the embodiments.

[0074] Example 1

[0075] The chemical composition of the nickel-manganese-copper-iron precursor in this embodiment is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1 CO3, the synthesis method includes the following specific steps:

[0076] (1) Preparation of metal solution and precipitant solution:

[0077] Add pure water, soluble metal salts, and the complexing agent sodium citrate to the metal preparation tank and stir until completely dissolved. All metal salts are sulfates: 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, and the total metal salt concentration is 2.0 mol / L. The molar ratio of sodium citrate to total metal salts is 0.03:1. The concentration of the sodium carbonate solution is 1.8 mol / L.

[0078] (2) Preparation of base liquid: Add 3 L of pure water, 0.3 mol of sodium carbonate and 0.07 mol of sodium citrate to a 10 L reactor, start stirring at a speed of 400 r / min, and heat to 50 °C.

[0079] (3) Reaction: Add the metal salt solution and the precipitant solution to the reactor in parallel, with a metal liquid flow rate of 300 mL / h, a molar ratio of sodium carbonate to metal element of 1.4:1, and a flow rate of 467 mL / h. When the volume of the solution in the reactor reaches the 10 L mark, begin to evacuate using a filter rod to maintain the liquid level constant. The reaction time is 24 h. The reaction pH is controlled between 8.0 and 9.0 by controlling the flow rate of sodium carbonate. After the addition of the solution is completed, age for 3 h.

[0080] (4) Post-treatment: 2 L of slurry was filtered and washed with water until the particle surface was neutral. The filter cake was immersed in a 0.005 mol / L CuSO4 solution at 50°C and stirred at a stirring speed of 200 r / min for 2 h. The filter cake was then filtered again and rinsed with hot water to remove any residual Cu on the particle surface. The filter cake was then rinsed with a 0.5 mol / L ammonium bicarbonate solution (the amount of ammonium bicarbonate was 20% of the sample mass) and then dried in a forced air drying oven at 120°C for 24 h until the moisture content of the sample was less than 2%.

[0081] (5) The dried filter cake is sieved to obtain a nickel-manganese-copper-iron carbonate precursor.

[0082] Example 2:

[0083] The chemical composition of the nickel-manganese-copper-iron precursor in this embodiment is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1 CO3, the synthesis method includes the following specific steps:

[0084] (1) Preparation of metal solution and precipitant solution:

[0085] Add pure water, soluble metal salts, and the complexing agent sodium citrate to the metal solution barrel 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, and the total concentration of metal salts is 2.0 mol / L. The molar ratio of sodium citrate to metal salt is 0.01:1. The complexing agent sodium oxalate solution is prepared separately, and the concentration of sodium oxalate solution is 0.2 mol / L. The concentration of sodium carbonate solution is 1.8 mol / L.

[0086] (2) Preparation of base liquid: Add 3 L of pure water, 0.3 mol of sodium carbonate, 0.02 mol of sodium citrate and 0.1 mol of sodium oxalate to a 10 L reactor, start stirring at a speed of 400 r / min, and heat to 50 °C.

[0087] (3) Reaction: Add metal salt solution, precipitant solution, and sodium oxalate solution to the reactor in parallel, with a metal liquid flow rate of 300 mL / h; a sodium carbonate to metal element molar ratio of 1.4:1, and a flow rate of 467 mL / h; a sodium oxalate solution flow rate of 150 mL / h, and a sodium oxalate to metal salt molar ratio of 0.05:1. When the volume of the solution in the reactor reaches the 10 L mark, begin to purify it with a filter rod, maintaining the liquid level constant. The reaction time is 24 h. The reaction pH is controlled between 8.0 and 9.0 by controlling the flow rate of sodium carbonate. After the addition of the solution is completed, age for 3 h.

[0088] (4) Post-treatment: 2 L of slurry was filtered and washed with water until the particle surface was neutral. The filter cake was immersed in a 0.005 mol / L CuSO4 solution at 50°C and stirred at a stirring speed of 200 r / min for 2 h. The filter cake was then filtered again and rinsed with hot water to remove any residual Cu on the particle surface. The filter cake was then rinsed with a 0.5 mol / L ammonium bicarbonate solution (the amount of ammonium bicarbonate was 20% of the sample mass) and then dried in a forced air drying oven at 120°C for 24 h until the moisture content of the sample was less than 2%.

[0089] (5) The dried filter cake is sieved to obtain a nickel-manganese-copper-iron carbonate precursor.

[0090] Example 3:

[0091] The chemical composition of the nickel-manganese-copper-iron precursor in this embodiment is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1 CO3, the synthesis method includes the following specific steps:

[0092] (1) Preparation of metal solution and precipitant solution:

[0093] Add pure water and soluble metal salts to the metal preparation tank and stir until completely dissolved. All metal salts are sulfates: 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, and the total concentration of the metal salts is 2.0 mol / L. Prepare a separate solution of the complexing agent, sodium oxalate, at a concentration of 0.2 mol / L. The concentration of the sodium carbonate solution is 1.8 mol / L.

[0094] (2) Preparation of base liquid: Add 3 L of pure water, 0.3 mol of sodium carbonate and 0.17 mol of sodium oxalate to a 10 L reactor, start stirring at a speed of 400 r / min, and heat to 50 °C.

[0095] (3) Reaction: Add metal salt solution, precipitant solution, and sodium oxalate solution to the reactor in parallel, with a metal liquid flow rate of 300 mL / h; a sodium carbonate to metal element molar ratio of 1.4:1, and a flow rate of 467 mL / h; a sodium oxalate solution flow rate of 300 mL / h, and a sodium oxalate to metal salt molar ratio of 0.1:1. When the volume of the solution in the reactor reaches the 10 L mark, begin to purify it with a filter rod, maintaining the liquid level constant. The reaction time is 24 h. The reaction pH is controlled between 8.0 and 9.0 by controlling the flow rate of sodium carbonate. After the addition of the solution is completed, age for 3 h.

[0096] (4) Post-treatment: 2 L of slurry was filtered and washed with water until the particle surface was neutral. The filter cake was immersed in a 0.005 mol / L CuSO4 solution at 50°C and stirred at a stirring speed of 200 r / min for 2 h. The filter cake was then filtered again and rinsed with hot water to remove any residual Cu on the particle surface. The filter cake was then rinsed with a 0.5 mol / L ammonium bicarbonate solution (the amount of ammonium bicarbonate was 20% of the sample mass) and then dried in a forced air drying oven at 120°C for 24 h until the moisture content of the sample was less than 2%.

[0097] (5) The dried filter cake is sieved to obtain a nickel-manganese-copper-iron carbonate precursor.

[0098] Example 4:

[0099] The chemical composition of the nickel-manganese-copper-iron precursor in this comparative example is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1CO3, the difference between the synthesis method and Example 1 is that in step (1), the molar ratio of sodium citrate to metal salt is 0.01:1, and the amount of sodium citrate added to the base solution is 0.023 mol.

[0100] Example 5:

[0101] The chemical composition of the nickel-manganese-copper-iron precursor in this comparative example is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1 CO3, the difference between the synthesis method 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 base solution is 0.234 mol.

[0102] Example 6:

[0103] The chemical composition of the nickel-manganese-copper-iron precursor in this comparative example is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1 CO3, the difference between the synthesis method and Example 1 is that in step (4), the filter cake is added into a CuSO4 solution with a concentration of 0.01 mol / L and immersed and stirred.

[0104] Example 7:

[0105] The chemical composition of the nickel-manganese-copper-iron precursor in this comparative example is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1 CO3, the difference between the synthesis method and Example 1 is that in step (4), the filter cake is added into a CuSO4 solution with a concentration of 0.001 mol / L and immersed and stirred.

[0106] Example 8:

[0107] The chemical composition of the nickel-manganese-copper-iron precursor in this embodiment is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1 CO3, the synthesis method includes the following specific steps:

[0108] (1) Preparation of metal solution and precipitant solution:

[0109] Add pure water, soluble metal salts, and the complexing agent sodium citrate to the metal solution tank and stir until completely dissolved. All metal salts are sulfates: 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, and the total metal salt concentration is 1.0 mol / L. The molar ratio of sodium citrate to metal salt is 0.2:1. The concentration of the sodium carbonate solution is 1.8 mol / L.

[0110] (2) Preparation of base liquid: Add 3 L of pure water, 1.5 mol of sodium carbonate and 0.28 mol of sodium citrate to a 10 L reactor, start stirring at a speed of 400 r / min, and heat to 80 °C.

[0111] (3) Reaction: Add metal salt solution and precipitant solution to the reactor in parallel, with a metal liquid flow rate of 300 mL / h, a molar ratio of sodium carbonate to metal element of 2.0:1, and a flow rate of 334 mL / h. When the volume of the solution in the reactor reaches the 10 L mark, begin to evacuate using a filter rod to maintain the liquid level constant. The reaction time is 48 h. The reaction pH is controlled between 10.0 and 11.0 by controlling the flow rate of sodium carbonate. After the addition of the solution is completed, age for 24 h.

[0112] (4) Post-treatment: 2 L of slurry was filtered and washed with water until the particle surface was neutral. The filter cake was immersed in a 0.05 mol / L CuSO4 solution at 80°C and stirred at 200 r / min for 2 h. The filter cake was then filtered again and rinsed with hot water to remove any residual Cu on the particle surface. The filter cake was then rinsed with ammonium bicarbonate solution (0.5 mol / L ammonium bicarbonate, equivalent to 20% of the sample mass) and then dried in a forced air drying oven at 120°C for 24 h until the sample moisture content was less than 2%.

[0113] (5) The dried filter cake is sieved to obtain a nickel-manganese-copper-iron carbonate precursor.

[0114] Example 9:

[0115] The chemical composition of the nickel-manganese-copper-iron precursor in this embodiment is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1 CO3, the synthesis method includes the following specific steps:

[0116] (1) Preparation of metal solution and precipitant solution:

[0117] Add pure water, soluble metal salts, and the complexing agent sodium citrate to the metal solution tank and stir until completely dissolved. All metal salts are sulfates: 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, and the total metal salt concentration is 1.5 mol / L. The molar ratio of sodium citrate to metal salt is 0.005:1. The concentration of the sodium carbonate solution is 1.0 mol / L.

[0118] (2) Preparation of base liquid: Add 3 L of pure water, 0.03 mol of sodium carbonate and 0.007 mol of sodium citrate to a 10 L reactor, start stirring at a speed of 400 r / min, and heat to 30 °C.

[0119] (3) Reaction: Add the metal salt solution and the precipitant solution to the reactor in parallel, with a metal liquid flow rate of 200 mL / h, a molar ratio of sodium carbonate to metal element of 1.2:1, and a flow rate of 500 mL / h. When the volume of the solution in the reactor reaches the 10 L mark, begin to evacuate using a filter rod, maintaining the liquid level constant. The reaction time is 12 h. During the reaction, the reaction pH is controlled between 8.0 and 9.0 by controlling the flow rate of sodium carbonate. After the addition of the solution is completed, age for 1 h.

[0120] (4) Post-treatment: 2 L of slurry was filtered and washed with water until the particle surface was neutral. The filter cake was immersed in a 0.001 mol / L CuSO4 solution at 30°C and stirred at a stirring speed of 100 r / min for 2 h. The filter cake was then filtered again and rinsed with hot water to remove any residual Cu on the particle surface. The sample was then rinsed with ammonium bicarbonate solution (0.5 mol / L ammonium bicarbonate, equivalent to 20% of the sample mass) and rinsed with hot water. After washing, the filter cake was dried in a forced air drying oven at 120°C for 24 h until the sample moisture content was less than 2%.

[0121] (5) The dried filter cake is sieved to obtain a nickel-manganese-copper-iron carbonate precursor.

[0122] Example 10:

[0123] In this comparative example, the amount of sulfate, namely nickel sulfate, manganese sulfate, ferrous sulfate and copper sulfate, is adjusted 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 other steps are the same as in Example 1.

[0124] Comparative Example 1:

[0125] The chemical composition of the nickel-manganese-copper-iron precursor in this comparative example is Ni 0.15Mn 0.60 Cu 0.15 Fe 0.1 CO3, the synthesis method differs from that of Example 1 in that no complexing agent is added and no CuSO4 solution is added for soaking and stirring. The method comprises the following specific steps:

[0126] (1) Preparation of metal solution and precipitant solution:

[0127] Add pure water and soluble metal salts to the metal preparation tank 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 metal salts is 2.0 mol / L, and the concentration of sodium carbonate solution is 1.8 mol / L.

[0128] (2) Preparation of base liquid: Add 3 L of pure water and 0.3 mol of sodium carbonate to a 10 L reactor, start stirring at a speed of 400 r / min, and heat to 50 °C.

[0129] (3) Reaction: Add the metal salt solution and the precipitant solution to the reactor in parallel, with a metal liquid flow rate of 300 mL / h, a molar ratio of sodium carbonate to metal element of 1.4:1, and a flow rate of 467 mL / h. When the volume of the solution in the reactor reaches the 10 L mark, begin to evacuate using a filter rod to maintain the liquid level constant. The reaction time is 24 h. The reaction pH is controlled between 8.0 and 9.0 by controlling the flow rate of sodium carbonate. After the addition of the solution is completed, age for 3 h.

[0130] (4) Post-treatment: Take 2 L of slurry for filtration and rinse with ammonium bicarbonate solution. The amount of ammonium bicarbonate used is 0.5 mol / L, which is 20% of the sample mass. Rinse with hot water. After washing, dry the filter cake in a blast drying oven at 120 ° C for 24 hours until the moisture content of the sample is less than 2%.

[0131] (5) The dried filter cake is sieved to obtain a nickel-manganese-copper-iron carbonate precursor.

[0132] Comparative Example 2:

[0133] The chemical composition of the nickel-manganese-copper-iron precursor in this comparative example is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1 CO3, the synthesis method is different from that of Example 1 in that a complexing agent is added and hot water is used to replace the copper sulfate solution.

[0134] Comparative Example 3:

[0135] The chemical composition of the nickel-manganese-copper-iron precursor in this comparative example is Ni0.15 Mn 0.60 Cu 0.15 Fe 0.1 CO3, the synthesis method is different from that of Example 1 in that no complexing agent is added.

[0136] Comparative Example 4:

[0137] The chemical composition of the nickel-manganese-copper-iron precursor in this comparative example is Ni 0.15 Mn 0.60 Cu 0.15 Fe 0.1 CO3, the difference between the synthesis method and Example 3 is that sodium oxalate is replaced by ammonia water, the concentration of ammonia water is 80g / L, and the concentration of ammonia water is controlled to be 2g / L through testing during the reaction.

[0138] The element contents in the precursors obtained in each embodiment and comparative example were detected. At the same time, the precursors were prepared into positive electrode materials and tested. The results are shown in the following table.

[0139] As can be seen from Figures 2-5, adding a suitable complexing agent (at least one of sodium citrate, citric acid, sodium oxalate and EDTA) can make Ni 2+ 、Mn 2+ 、Fe 2+ 、Cu 2+ The four ions co-precipitated and there was no segregation on the surface of the sample particles. Ammonia as a complexing agent would aggravate the segregation of the Mn element and form separate blocky particles.

[0140] As can be seen from Table 1, the element contents of the examples are within the error range of the target values, and the Na and S contents are both lower than 2000 ppm, and the batch stability of the examples is significantly improved.

[0141] As can be seen from Table 1, the positive electrode materials prepared in the Examples and Comparative Examples had initial discharge capacities ranging from 132 to 156 mAh / g in the 0.1C charge-discharge performance test. The active material obtained in Example 2 had the highest initial discharge specific capacity and the highest capacity retention after 100 cycles at 0.5C, demonstrating the best performance. Therefore, the nickel-manganese-copper-iron precursor sample prepared by adding a complexing agent, strictly controlling the reaction conditions, and using a copper salt solution immersion and stirring process can effectively improve the capacity and cycle performance of the positive electrode material, thereby enhancing the electrochemical performance of the material.

[0142] The preparation of the positive electrode materials tested in the table above involves first calcining the carbonate precursors obtained in the examples and comparative examples at 500°C for 6 hours in a muffle furnace, followed by cooling. The sintered precursors are then mixed with Na2CO3 in a plowshare mixer at a molar ratio of 1.0:1.05. The mixture is then calcined at 850°C for 12 hours in a muffle furnace, followed by cooling to obtain the positive electrode materials.

[0143] Preparation of the positive electrode for the test: The positive electrode material was evenly mixed with conductive carbon black and polyvinylidene fluoride in 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 a positive electrode slurry. The positive electrode slurry was coated on a clean aluminum foil and placed in a vacuum drying oven at 80°C for 12 hours to prepare a positive electrode for the test.

[0144] Charge and Discharge Testing: In a glove box, sodium sheets were used as the negative electrode to assemble 2032-type button cells. Charge and discharge tests were conducted. The charge and discharge performance was measured at a 0.1C rate, as well as the cycle retention after 100 cycles at 0.5C. The test voltage window was 1.5-4.2V, and the test temperature was 25°C. The test results are detailed in the table above. Industrial Applicability

[0145] The present disclosure can realize Ni 2+ 、Mn 2+ 、Fe 2+ 、Cu 2+ The four metal ions are complexed and slowly released under the action of the precipitant, achieving co-precipitation of the four metal ions, making the prepared precursor morphology uniform and without segregation. The particle size can also be effectively controlled by adjusting the co-precipitation and aging time as well as the concentration of each reagent, thereby improving the sphericity of the precursor particles in the later forming process.

[0146] The present invention discloses a post-processing step for the precipitation product, wherein the precipitation product is placed in an aqueous solution of copper salt for soaking, so that Cu 2+ and the residual CO3 in the particles 2- Combined with, supplement the content of Cu element in the precursor material.

[0147] The present disclosure discloses a post-processing step for the precipitation product, in which the precipitation product is immersed in an aqueous solution of copper salt to dissolve impurity elements such as sodium and sulfur in the precipitation product, thereby reducing the content of impurities such as sodium and sulfur in the precursor, which is beneficial to improving the batch stability and comprehensive performance of the precursor material.

Claims

1. A method for preparing a nickel-manganese-copper-iron carbonate precursor, characterized in that: include: Co-precipitation: gradually add Ni to the base solution containing sodium carbonate and complexing agent. 2+ , Mn 2+ , Fe 2+ , Cu 2+ Metal ion solutions of four metal ions, a complexing agent solution and a sodium carbonate solution are prepared, the pH of the reaction solution is maintained between 8.0 and 11.0, coprecipitation and aging are performed, and solid-liquid separation is performed on the reaction solution to obtain carbonate particles; the complexing agent is at least one of sodium citrate, citric acid, sodium oxalate and EDTA; Post-treatment: The carbonate particles washed with water until the particle surface is neutral are immersed in an aqueous solution of copper salt, and then solid-liquid separation is performed and the solid phase is washed to obtain a nickel-manganese-copper-iron carbonate precursor.

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 base liquid is 0.01 mol / L-0.5 mol / L.

3. The method for preparing a nickel-manganese-copper-iron carbonate precursor according to claim 1 or 2, characterized in that: The concentration of the complexing agent in the base 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 any one of claims 1 to 3, characterized in that: The metal ion solution contains Ni 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.

5. The method for preparing the nickel-manganese-copper-iron carbonate precursor according to any one of claims 1 to 4, characterized in that: The molar amount of the complexing agent in the complexing agent solution is equal to the molar amount of Ni in the metal ion solution. 2+ , Mn 2+ , Fe 2+ , Cu 2+ The total molar ratio of the four metal ions is (0.005-0.2):

1.

6. The method for preparing the nickel-manganese-copper-iron carbonate precursor according to any one of claims 1 to 5, characterized in that: The molar amount of sodium carbonate added to the bottom solution is proportional 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.

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

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

9. The method for preparing a nickel-manganese-copper-iron carbonate precursor according to any one of claims 1 to 8, characterized in that: The temperature of the aging step is 30° C.-80° C., and the time is 0 h-24 h.

10. The method for preparing a nickel-manganese-copper-iron carbonate precursor according to any one of claims 1 to 9, characterized in that: Add metal ion solution, complexing agent solution and sodium carbonate solution to the base liquid until the volume of the reaction liquid is 2-0.5:1 to the volume of the base liquid, then use a filter rod to pump out the solution or a concentrator to concentrate the solution, keeping the volume of the reaction liquid to the volume of the base liquid at a ratio of 2-0.5:

1.

11. The method for preparing a nickel-manganese-copper-iron carbonate precursor according to claim 10, characterized in that: The flow acceleration of the metal ion solution is 0.05 L / h-0.2 L / h per liter of base liquid.

12. The method for preparing a nickel-manganese-copper-iron carbonate precursor according to any one of claims 1 to 11, characterized in that: The copper salt is copper sulfate or copper nitrate, and the concentration of the copper salt in the aqueous solution of the copper salt is 0.001 mol / L-0.05 mol / L.

13. The method for preparing a nickel-manganese-copper-iron carbonate precursor according to any one of claims 1 to 12, characterized in that: The total molar amount of copper salt in the aqueous solution of copper salt is (z-z0)n / K, in 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 carbonate particles immersed in the aqueous solution of copper salt, in mol; K is a constant and K∈(0.6-0.8).

14. The method for preparing a nickel-manganese-copper-iron carbonate precursor according to any one of claims 1 to 13, characterized in that: The soaking step is performed for 1 hour to 24 hours at a temperature of 30° C. to 80° C.

15. The method for preparing a nickel-manganese-copper-iron carbonate precursor according to any one of claims 1 to 14, characterized in that: The soaking step is accompanied by stirring, and the stirring speed is 100r / min-300r / min.

16. The method for preparing a nickel-manganese-copper-iron carbonate precursor according to any one of claims 1 to 15, characterized in that: The washing step comprises washing with water, washing with ammonium bicarbonate solution and washing with water in sequence.

17. The method for preparing the nickel-manganese-copper-iron carbonate precursor according to claim 16, characterized in that: The temperature of the washing liquid in the washing step is 30°C-80°C.

18. The method for preparing a nickel-manganese-copper-iron carbonate precursor according to claim 16 or 17, characterized in that: 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.

19. The method for preparing a nickel-manganese-copper-iron carbonate precursor according to any one of claims 1 to 18, characterized in that: After the washing step, the solid is dried at a temperature of 80° C. to 120° C. for 24 h to 48 h until the moisture content of the sample is less than 2 wt %.

20. A nickel-manganese-copper-iron carbonate precursor obtained by the method according to any one of claims 1 to 19, characterized in that: The general formula is 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.

21. Use of a nickel-manganese-copper-iron carbonate precursor obtained by the method according to any one of claims 1 to 19 in preparing a positive electrode material for a sodium ion battery.

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