Coating-modified iron-copper-manganese-based precursor, preparation method therefor, and use thereof

Abstract

A coating-modified iron-copper-manganese-based precursor, a preparation method therefor, and a use thereof. A coating layer of the coating-modified iron-copper-manganese-based precursor is uniformly distributed. The preparation method comprises using a coprecipitation method to obtain CuaFebMnc(OH)2, and then using the coprecipitation method again for a coating reaction to obtain the coating-modified iron-copper-manganese-based precursor coated with a zirconium source and an aluminum source. The addition of zirconium can improve the stability of a positive electrode material in a high-voltage area, and the addition of aluminum can improve the cycling performance of the positive electrode material. The synergistic effect of zirconium and aluminum ensures the electrochemical performance of the obtained coating-modified iron-copper-manganese-based precursor. In addition, the preparation method is simple to operate, the obtained coating layer is uniform, and the coating amount is controllable. The preparation method is suitable for industrial production.

Description

Coated modified iron-copper-manganese based precursor and its preparation method and application Technical Field

[0001] The present application belongs to the field of battery technology and relates to a precursor, and in particular to a coated and modified iron-copper-manganese-based precursor and a preparation method and application thereof. Background Art

[0002] As the use of lithium-ion batteries continues to increase, the prices of key materials for lithium-ion batteries, such as lithium, nickel, and cobalt, continue to rise. This price factor has, to a certain extent, restricted the development of lithium-ion batteries. Sodium-ion batteries are currently recognized as one of the more ideal alternative energy sources to lithium-ion batteries.

[0003] Sodium and lithium belong to the same main group, sharing similar physical and chemical properties and electrochemical reaction mechanisms. Furthermore, compared to lithium batteries, sodium-ion batteries offer advantages such as abundant resources, low cost, and widespread distribution. Consequently, sodium-ion batteries have gradually become a research hotspot in the energy storage field. The large ionic radius and slow kinetic rate of sodium ions make it difficult for them to intercalate and deintercalate from cathode materials. The capacity of cathode materials determines the overall cell capacity of sodium-ion batteries. Therefore, developing high-performance cathode materials for sodium-ion batteries is crucial for their commercial application.

[0004] Layered metal oxide positive electrode materials are currently a common type of sodium ion positive electrode material. The main problems of layered transition metal oxide positive electrode materials are poor air stability, multi-phase transition and unsatisfactory electrochemical performance. During long-term charge and discharge cycles, the layered metal oxide positive electrode will undergo structural degradation and various side reactions, which will deteriorate the overall performance of sodium ion batteries and seriously limit the large-scale promotion and application of sodium ion batteries.

[0005] CN116239160A discloses a polysilicic acid salt coated modified ternary sodium battery precursor and its preparation method, which prepares a polysilicic acid salt material by a one-step solid phase method, further compounds it with the ternary precursor, and finally obtains a polysilicic acid salt coated modified ternary sodium battery precursor by high temperature sintering. x X y SiO4, M is Na, K, X is Ma, Al. The solid-phase method and high-temperature calcination method for coating the sodium cathode precursor require high energy consumption, and the thickness and uniformity of the coating layer are difficult to accurately control.

[0006] CN114590838A discloses an amorphous metal sulfide-coated modified binary manganese-based sodium precursor and a preparation method thereof, comprising the following steps: (1) adding a manganese salt, a transition metal salt, and an additive to a ball mill, thoroughly milling them uniformly, and calcining them at high temperature to obtain a binary metal oxide; (2) dispersing the binary metal oxide, a soluble manganese salt, and terephthalic acid in an organic solvent, and after the dispersion is completed, placing the dispersion in a polytetrafluoroethylene reactor for a hydrothermal reaction; (3) after the hydrothermal reaction is completed, subjecting the material to a high-temperature fluidized bed treatment, followed by a rapid cooling treatment, to obtain an amorphous metal sulfide-coated modified binary manganese-based sodium precursor. This method uses an amorphous metal sulfide to coat the precursor, resulting in a complex reaction process and difficulty in industrial production.

[0007] To this end, it is necessary to provide a coated and modified iron-copper-manganese-based precursor that is uniformly coated and can control the thickness of the coating layer and is suitable for industrial production, as well as a preparation method and application thereof.

[0008] Summary of the Invention

[0009] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0010] The purpose of the present application is to provide a coated modified iron-copper-manganese-based precursor and its preparation method and application. The coated modified iron-copper-manganese-based precursor has a uniform coating layer distribution, a controllable coating amount, is conducive to industrial production, and has good commercial prospects; moreover, the obtained positive electrode material has excellent electrochemical properties.

[0011] To achieve this goal, this application adopts the following technical solutions:

[0012] In a first aspect, the present application provides a method for preparing a coated and modified iron-copper-manganese-based precursor, the preparation method comprising the following steps:

[0013] (1) Adding iron-manganese mixed salt solution, copper complex solution, precipitant solution and complexing agent solution to the base liquid to carry out coprecipitation reaction. After the coprecipitation reaction reaches the target particle size, Cu a Fe b Mn c (OH)2, where 0 <a≤0.3,0<b≤0.5,0<c≤0.5,a+b+c=1;

[0014] (2) Zirconium source solution, aluminum source solution, precipitant solution and complexing agent solution are continuously added to the base liquid to carry out coating reaction. The coating reaction is stopped after the target particle size is reached to obtain the coated and modified iron-copper-manganese-based precursor.

[0015] The preparation method provided in this application utilizes a coprecipitation method to obtain Cu aFe b Mn c (OH)2, and then continue to use the co-precipitation method to carry out the coating reaction to obtain a coated and modified iron-copper-manganese-based precursor coated with a zirconium source and an aluminum source. The addition of zirconium can improve the stability of the positive electrode material in the high voltage region, and the addition of aluminum can improve the cyclability of the positive electrode material. The synergistic effect of zirconium and aluminum ensures the electrochemical performance of the obtained coated and modified iron-copper-manganese-based precursor. Moreover, the preparation method provided in this application is simple to operate, the obtained coating layer is uniform, and the coating amount is controllable, which is suitable for industrial production.

[0016] In one embodiment, the pH value of the coprecipitation reaction in step (1) is 7-10.

[0017] In one embodiment, the concentration of the complexing agent in the coprecipitation reaction in step (1) is 1-6 g / L.

[0018] In one embodiment, the temperature of the coprecipitation reaction in step (1) is 30-60°C.

[0019] In one embodiment, the target particle size of the coprecipitation reaction in step (1) is D50 of 2-5 μm.

[0020] In one embodiment, the coprecipitation reaction in step (1) is accompanied by a first stirring.

[0021] In one embodiment, the first stirring speed is 150-500 rpm.

[0022] In one embodiment, the pH value of the coating reaction in step (2) is 10-12.

[0023] In one embodiment, the concentration of the complexing agent in the coating reaction in step (2) is 0.5-6 g / L.

[0024] In one embodiment, the temperature of the coating reaction in step (2) is 50-80°C.

[0025] In one embodiment, the target particle size of the coating reaction in step (2) is D50 of 5-8 μm.

[0026] In one embodiment, the coating reaction in step (2) is accompanied by a second stirring.

[0027] In one embodiment, the second stirring speed is 500-1000 rpm.

[0028] In one embodiment, the coating amount of zirconium in the coated and modified iron-copper-manganese-based precursor is 100-3000 ppm.

[0029] In one embodiment, the coating amount of aluminum in the coated and modified iron-copper-manganese-based precursor is 100-3000 ppm.

[0030] In a second aspect, the present application provides a coated and modified iron-copper-manganese-based precursor, which is prepared by the preparation method described in the first aspect.

[0031] In a third aspect, the present application provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0032] The sodium salt is mixed with the coated and modified iron-copper-manganese-based precursor described in the second aspect, and calcined to obtain the positive electrode material.

[0033] In one embodiment, the sodium salt includes any one of sodium carbonate, sodium hydroxide or sodium nitrate, or a combination of at least two thereof.

[0034] In one embodiment, the molar ratio of sodium in the sodium salt to the coated modified iron-copper-manganese-based precursor is (1-1.05):1.

[0035] In one embodiment, the calcination temperature is 400-1300° C. and the calcination time is 12-48 hours.

[0036] In a fourth aspect, the present application provides a positive electrode material, which is prepared by the preparation method described in the third aspect.

[0037] In a fifth aspect, the present application provides a sodium ion battery, which includes the coated and modified iron-copper-manganese-based precursor described in the second aspect, or includes the positive electrode material described in the fourth aspect.

[0038] Compared with the prior art, this application has the following beneficial effects:

[0039] The preparation method provided in this application utilizes a coprecipitation method to obtain Cu a Fe b Mn c (OH)2, and then continue to use the co-precipitation method to carry out the coating reaction to obtain a coated and modified iron-copper-manganese-based precursor coated with a zirconium source and an aluminum source. The addition of zirconium can improve the stability of the positive electrode material in the high voltage region, and the addition of aluminum can improve the cyclability of the positive electrode material. The synergistic effect of zirconium and aluminum ensures the electrochemical performance of the obtained coated and modified iron-copper-manganese-based precursor. Moreover, the preparation method provided in this application is simple to operate, the obtained coating layer is uniform, and the coating amount is controllable, which is suitable for industrial production.

[0040] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0042] FIG1 is a SEM image of the coated and modified iron-copper-manganese-based precursor obtained in Example 1. DETAILED DESCRIPTION

[0043] The technical solution of the present application is further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations of the present application.

[0044] A certain embodiment of the present application provides a method for preparing a coated and modified iron-copper-manganese-based precursor, the preparation method comprising the following steps:

[0045] (1) Adding iron-manganese mixed salt solution, copper complex solution, precipitant solution and complexing agent solution to the base liquid to carry out coprecipitation reaction. After the coprecipitation reaction reaches the target particle size, Cu a Fe b Mn c (OH)2, where 0 <a≤0.3,0<b≤0.5,0<c≤0.5,a+b+c=1;

[0046] (2) Zirconium source solution, aluminum source solution, precipitant solution and complexing agent solution are continuously added to the base liquid to carry out coating reaction. The coating reaction is stopped after the target particle size is reached to obtain the coated and modified iron-copper-manganese-based precursor.

[0047] The preparation method provided in this application utilizes a coprecipitation method to obtain Cu a Fe b Mn c (OH)2, and then continue to use the co-precipitation method to carry out the coating reaction to obtain a coated and modified iron-copper-manganese-based precursor coated with a zirconium source and an aluminum source. The addition of zirconium can improve the stability of the positive electrode material in the high voltage area, and the addition of aluminum can improve the cyclability of the positive electrode material. The synergistic effect of zirconium and aluminum ensures the electrochemical performance of the obtained coated and modified iron-copper-manganese-based precursor. Moreover, the preparation method provided in the present application is simple to operate, the obtained coating layer is uniform, and the coating amount is controllable, which is suitable for industrial production.

[0048] In step (1) of this application, Cu a Fe b Mn c (OH)2, where 0 <a≤0.3,0<b≤0.5,0<c≤0.5,a+b+c=1。

[0049] Among them, the value of a satisfies 0 < a ≤ 0.3. For example, it can be 0.05, 0.1, 0.15, 0.2, 0.25 or 0.3, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0050] The value of b satisfies 0 < b ≤ 0.5. For example, it can be 0.05, 0.1, 0.2, 0.3, 0.4 or 0.5, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0051] The value of c satisfies 0 < c ≤ 0.5. For example, it can be 0.05, 0.1, 0.2, 0.3, 0.4 or 0.5, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0052] In some embodiments, the bottom solution in step (1) is a combination of water, a complexing agent solution, and a precipitating agent solution.

[0053] In some embodiments, the pH value of the bottom solution in step (1) is 7.5 - 12. For example, it can be 7.5, 8, 9, 10, 11 or 12, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0054] In some embodiments, in the bottom solution of step (1), the concentration of the complexing agent is 0.1 - 10 g / L. For example, it can be 0.1 g / L, 2 g / L, 3 g / L, 5 g / L, 6 g / L, 8 g / L or 10 g / L, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable, and it can be optionally​​​​​​​​​​​The soluble ferrous salt includes any one or a combination of at least two of ferrous sulfate, ferrous nitrate or ferrous chloride. Typical but non-limiting combinations include a combination of ferrous sulfate and ferrous nitrate, a combination of ferrous nitrate and ferrous chloride, a combination of ferrous sulfate and ferrous chloride, or a combination of ferrous sulfate, ferrous nitrate and ferrous chloride.

[0059] The soluble manganese salt includes any one or a combination of at least two of manganese sulfate, manganese nitrate or manganese chloride. Typical but non-limiting combinations include a combination of manganese sulfate and manganese nitrate, a combination of manganese nitrate and manganese chloride, a combination of manganese sulfate and manganese chloride, or a combination of manganese sulfate, manganese nitrate and manganese chloride.

[0060] In certain embodiments, the copper complex solution consists of water, a soluble copper salt, and a complexing agent.

[0061] The soluble copper salts include, but are not limited to, copper sulfate and / or copper chloride.

[0062] The complexing agent in the copper complex solution includes but is not limited to ammonia water and / or sodium fluoride, wherein the molar ratio of copper ions to complexing ions is 1:(1-8), for example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7 or 1:8, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0063] In certain embodiments, the pH value of the coprecipitation reaction in step (1) is 7-10, for example, 7, 8, 9 or 10, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0064] In certain embodiments, the concentration of the complexing agent in the coprecipitation reaction in step (1) is 1-6 g / L, for example, 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L or 6 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0065] In certain embodiments, the temperature of the coprecipitation reaction in step (1) is 30-60°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0066] In certain embodiments, the target particle size D50 of the coprecipitation reaction in step (1) is 2-5 μm, for example, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm or 5 μm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0067] In certain embodiments, the coprecipitation reaction in step (1) is accompanied by a first stirring.

[0068] In certain embodiments, the first stirring speed is 150-500 rpm, for example, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm or 500 rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0069] In certain embodiments, the zirconium source solution described herein is composed of a soluble zirconium salt, water, and an inorganic acid, wherein the inorganic acid comprises hydrochloric acid and / or sulfuric acid, and the composition of the inorganic acid causes the pH value of the zirconium source solution to be 2-4, thereby inhibiting the hydrolysis of zirconium therein.

[0070] The present application does not impose any specific limitation on the concentration of the zirconium source solution, as long as the amount of zirconium coating in the final coated and modified iron-copper-manganese-based precursor meets the process requirements.

[0071] In certain embodiments, the soluble zirconium salt includes zirconium sulfate and / or zirconium chloride.

[0072] In certain embodiments, the aluminum source solution described herein is composed of sodium metaaluminate solution and ammonia water. The ratio of sodium metaaluminate solution to ammonia water in the present application is not specifically limited, as long as it can meet the complexing agent concentration and pH requirements during the reaction.

[0073] The present application does not impose any specific limitation on the concentration of the aluminum source solution, as long as the amount of aluminum coating in the final coated and modified iron-copper-manganese-based precursor meets the process requirements.

[0074] In certain embodiments, the pH value of the coating reaction in step (2) is 10-12, for example, 10, 10.5, 11, 11.5 or 12, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0075] In certain embodiments, the concentration of the complexing agent in the coating reaction in step (2) is 0.5-6 g / L, for example, 0.5 g / L, 1 g / L, 2 g / L, 3 g / L, 5 g / L or 6 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0076] In certain embodiments, the temperature of the coating reaction in step (2) is 50-80°C, for example, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0077] In certain embodiments, the target particle size D50 of the coating reaction in step (2) reaches 5-8 μm, for example, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm or 8 μm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0078] In certain embodiments, the coating reaction in step (2) is accompanied by a second stirring.

[0079] In certain embodiments, the second stirring speed is 500-1000 rpm, for example, 500 rpm, 600 rpm, 800 rpm, 900 rpm or 1000 rpm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0080] In some embodiments, the coating amount of zirconium in the coated modified iron-copper-manganese-based precursor is 100-3000 ppm, for example, it can be 100 ppm, 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm or 3000 ppm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0081] In the present application, the “coating amount of zirconium” refers to the mass fraction of the zirconium element in the coated and modified iron-copper-manganese-based precursor.

[0082] In some embodiments, the coating amount of aluminum in the coated modified iron-copper-manganese-based precursor is 100-3000 ppm, for example, it can be 100 ppm, 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm or 3000 ppm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0083] In this application, the "amount of aluminum coating" refers to the mass fraction of the aluminum element in the coated and modified iron-copper-manganese-based precursor.

[0084] The precipitant solution used in this application includes sodium hydroxide solution and / or potassium hydroxide solution, and sodium hydroxide solution can be selected.

[0085] This application does not impose any specific restrictions on the concentration of the precipitant solution, as long as the pH values ​​of the base liquid, coprecipitation reaction, and coating reaction can meet the process requirements.

[0086] The complexing agent solution used in this application includes any one of ammonia water, oxalic acid or acetic acid or a combination of at least two of them. Typical but non-limiting combinations include a combination of ammonia water and oxalic acid, a combination of ammonia water and acetic acid, a combination of oxalic acid and acetic acid, or a combination of ammonia water, oxalic acid and acetic acid. Ammonia water can be selected.

[0087] This application does not impose any specific restrictions on the concentration of the complexing agent solution, as long as the concentration of the complexing agent in the base solution, coprecipitation reaction and coating reaction can meet the process requirements.

[0088] A certain embodiment of the present application provides a coated and modified iron-copper-manganese-based precursor.

[0089] An embodiment of the present application provides a method for preparing a positive electrode material, the method comprising the following steps:

[0090] The sodium salt and the coated modified iron-copper-manganese-based precursor are mixed and calcined to obtain the positive electrode material.

[0091] In certain embodiments, the sodium salt includes any one or a combination of at least two of sodium carbonate, sodium hydroxide or sodium nitrate. Typical but non-limiting combinations include a combination of sodium carbonate and sodium hydroxide, a combination of sodium carbonate and sodium nitrate, a combination of sodium hydroxide and sodium nitrate, or a combination of sodium carbonate, sodium hydroxide and sodium nitrate.

[0092] In certain embodiments, in order to compensate for the ignition loss of the sodium salt during the calcination process, the molar ratio of sodium in the sodium salt to the coated modified iron-copper-manganese-based precursor is (1-1.05):1, for example, it can be 1:1, 1.01:1, 1.02:1, 1.03:1, 1.04:1 or 1.05:1, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0093] In certain embodiments, the calcination temperature is 400-1300° C., and the calcination time is 12-48 hours.

[0094] The calcination temperature is 400-1300°C, for example, 400°C, 500°C, 600°C, 800°C, 1000°C, 1200°C or 1300°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0095] The calcination time is 12-48 hours, for example, 12 hours, 15 hours, 16 hours, 18 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours or 48 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0096] A certain embodiment of the present application provides a positive electrode material, which is prepared by the preparation method in certain embodiments.

[0097] A certain embodiment of the present application provides a sodium ion battery, which includes the coated and modified iron-copper-manganese-based precursor in certain embodiments, or includes the positive electrode material in certain embodiments.

[0098] Example 1

[0099] This embodiment provides a method for preparing a coated and modified iron-copper-manganese-based precursor, the preparation method comprising the following steps:

[0100] (1) Under nitrogen atmosphere, iron-manganese mixed salt solution, copper complex solution, precipitant solution and complexing agent solution are added to the bottom liquid to carry out coprecipitation reaction. After the coprecipitation reaction reaches the target particle size D50 of 4 μm, the feeding is stopped, and the mixture is allowed to stand for aging. After conventional washing, centrifugation and drying, Cu 0.2 Fe 0.3 Mn 0.5 (OH)2;

[0101] The base liquid is a combination of water, ammonia water and sodium hydroxide solution, the pH value of the base liquid is 10, and the concentration of the complexing agent is 3.5g / L;

[0102] The metal salts in the iron-manganese mixed salt solution include ferrous sulfate and manganese sulfate, and the total concentration of ferrous ions and manganese ions is 0.8 mol / L;

[0103] The copper complex solution is a combination of 0.3 mol / L copper sulfate solution and 0.6 mol / L ammonia water;

[0104] The precipitant solution is sodium hydroxide solution, and the complexing agent solution is ammonia water;

[0105] The amount of iron-manganese mixed salt solution and copper complex solution added is such that the final product is Cu 0.2 Fe 0.3 Mn 0.5 (OH)2;

[0106] The amounts of the precipitant solution and the complexing agent solution were controlled so that the pH value of the coprecipitation reaction was 9.5, the ammonia concentration was 3 g / L, the temperature was 48° C., and the stirring speed was 400 rpm;

[0107] (2) Under a nitrogen atmosphere, the zirconium source solution, aluminum source solution, precipitant solution and complexing agent solution are continuously added to the base liquid to carry out a coating reaction. The coating reaction is stopped after the target particle size D50 reaches 6.5 μm, and the particles are allowed to stand for 6 hours. After conventional washing, centrifugation and drying, the coated and modified iron-copper-manganese-based precursor is obtained.

[0108] The zirconium source solution is a sulfuric acid solution of zirconium sulfate, the concentration of zirconium sulfate is 0.1 mol / L, and the pH value is 3;

[0109] The aluminum source solution is a mixture of 0.2 mol / L sodium metaaluminate solution and 0.3 mol / L ammonia water;

[0110] The precipitant solution is sodium hydroxide solution, and the complexing agent solution is ammonia water;

[0111] The amounts of the precipitant solution and the complexing agent solution were controlled so that the pH value of the coating reaction was 11, the ammonia concentration was 4 g / L, the temperature was 58°C, and the stirring speed was 800 rpm;

[0112] In the obtained coated and modified iron-copper-manganese-based precursor, the coating amount of zirconium is 1000 ppm, and the coating amount of aluminum is 1000 ppm.

[0113] The SEM image of the coated and modified iron-copper-manganese-based precursor finally obtained in this example is shown in FIG1 .

[0114] Example 2

[0115] This embodiment provides a method for preparing a coated and modified iron-copper-manganese-based precursor, the preparation method comprising the following steps:

[0116] (1) Under nitrogen atmosphere, iron-manganese mixed salt solution, copper complex solution, precipitant solution and complexing agent solution are added to the bottom liquid to carry out coprecipitation reaction. After the coprecipitation reaction reaches the target particle size D50 of 2 μm, the feeding is stopped, and the mixture is allowed to stand for aging. After conventional washing, centrifugation and drying, Cu 0.2 Fe 0.3 Mn 0.5 (OH)2;

[0117] The base liquid is a combination of water, ammonia water and sodium hydroxide solution, the pH value of the base liquid is 7.5, and the concentration of the complexing agent is 0.1 g / L;

[0118] The metal salts in the iron-manganese mixed salt solution include ferrous sulfate and manganese sulfate, and the total concentration of ferrous ions and manganese ions is 0.1 mol / L;

[0119] The copper complex solution is a combination of 0.3 mol / L copper sulfate solution and 0.6 mol / L ammonia water;

[0120] The precipitant solution is sodium hydroxide solution, and the complexing agent solution is ammonia water;

[0121] The amount of iron-manganese mixed salt solution and copper complex solution added is such that the final product is Cu 0.2 Fe 0.3 Mn 0.5 (OH)2;

[0122] The amounts of the precipitant solution and the complexing agent solution were controlled so that the pH value of the coprecipitation reaction was 7, the ammonia concentration was 1 g / L, the temperature was 30° C., and the stirring speed was 500 rpm;

[0123] (2) Under a nitrogen atmosphere, a zirconium source solution, an aluminum source solution, a precipitant solution, and a complexing agent solution are continuously added to the base liquid to carry out a coating reaction. The coating reaction is stopped after the target particle size D50 reaches 5 μm, and the particles are allowed to stand for 6 hours. After conventional washing, centrifugation, and drying, the coated and modified iron-copper-manganese-based precursor is obtained.

[0124] The zirconium source solution is a sulfuric acid solution of zirconium sulfate, the concentration of zirconium sulfate is 0.1 mol / L, and the pH value is 2;

[0125] The aluminum source solution is a mixture of 0.2 mol / L sodium metaaluminate solution and 0.3 mol / L ammonia water;

[0126] The precipitant solution is sodium hydroxide solution, and the complexing agent solution is ammonia water;

[0127] The amounts of the precipitant solution and the complexing agent solution were controlled so that the pH value of the coating reaction was 10, the ammonia concentration was 0.5 g / L, the temperature was 50°C, and the stirring speed was 1000 rpm;

[0128] In the obtained coated and modified iron-copper-manganese-based precursor, the coating amount of zirconium is 1000 ppm, and the coating amount of aluminum is 1000 ppm.

[0129] Example 3

[0130] This embodiment provides a method for preparing a coated and modified iron-copper-manganese-based precursor, the preparation method comprising the following steps:

[0131] (1) Under nitrogen atmosphere, iron-manganese mixed salt solution, copper complex solution, precipitant solution and complexing agent solution are added to the bottom liquid to carry out coprecipitation reaction. After the coprecipitation reaction reaches the target particle size D50 of 5 μm, the feeding is stopped, and the mixture is allowed to stand for aging. After conventional washing, centrifugation and drying, Cu 0.2 Fe 0.3 Mn 0.5 (OH)2;

[0132] The base liquid is a combination of water, ammonia water and sodium hydroxide solution, the pH value of the base liquid is 10, and the concentration of the complexing agent is 6g / L;

[0133] The metal salts in the iron-manganese mixed salt solution include ferrous sulfate and manganese sulfate, and the total concentration of ferrous ions and manganese ions is 5 mol / L;

[0134] The copper complex solution is a combination of 0.3 mol / L copper sulfate solution and 0.6 mol / L ammonia water;

[0135] The precipitant solution is sodium hydroxide solution, and the complexing agent solution is ammonia water;

[0136] The amount of iron-manganese mixed salt solution and copper complex solution added is such that the final product is Cu 0.2 Fe 0.3 Mn 0.5 (OH)2;

[0137] The amounts of the precipitant solution and the complexing agent solution were controlled so that the pH value of the coprecipitation reaction was 10, the ammonia concentration was 6 g / L, the temperature was 60° C., and the stirring speed was 150 rpm;

[0138] (2) Under a nitrogen atmosphere, a zirconium source solution, an aluminum source solution, a precipitant solution, and a complexing agent solution are continuously added to the base liquid to carry out a coating reaction. The coating reaction is stopped after the target particle size D50 reaches 8 μm, and the particles are allowed to stand for 6 hours. After conventional washing, centrifugation, and drying, the coated and modified iron-copper-manganese-based precursor is obtained.

[0139] The zirconium source solution is a sulfuric acid solution of zirconium sulfate, the concentration of zirconium sulfate is 0.1 mol / L, and the pH value is 4;

[0140] The aluminum source solution is a mixture of 0.2 mol / L sodium metaaluminate solution and 0.3 mol / L ammonia water;

[0141] The precipitant solution is sodium hydroxide solution, and the complexing agent solution is ammonia water;

[0142] The amounts of the precipitant solution and the complexing agent solution were controlled so that the pH value of the coating reaction was 12, the ammonia concentration was 6 g / L, the temperature was 80°C, and the stirring speed was 500 rpm;

[0143] In the obtained coated and modified iron-copper-manganese-based precursor, the coating amount of zirconium is 1000 ppm, and the coating amount of aluminum is 1000 ppm.

[0144] Example 4

[0145] This example provides a method for preparing a coated and modified iron-copper-manganese-based precursor. The method is the same as in Example 1, except that the flow rates of the zirconium source solution and the aluminum source solution are adjusted so that the coated and modified iron-copper-manganese-based precursor has a zirconium coating amount of 100 ppm and an aluminum coating amount of 3000 ppm.

[0146] Example 5

[0147] This example provides a method for preparing a coated and modified iron-copper-manganese-based precursor. The method is the same as in Example 1, except that the flow rates of the zirconium source solution and the aluminum source solution are adjusted so that the coated and modified iron-copper-manganese-based precursor has a zirconium coating amount of 3000 ppm and an aluminum coating amount of 100 ppm.

[0148] Example 6

[0149] This embodiment provides a method for preparing a coated modified iron-copper-manganese based precursor, in addition to adjusting the ratio of ferrous ions to manganese ions in the iron-manganese mixed salt solution and adjusting the flow rate of the iron-manganese mixed salt solution and the copper complex solution, so that the final product obtained in step (1) is Cu 0.1 Fe 0.4 Mn 0.5 Except for (OH)2, the rest are the same as in Example 1.

[0150] Example 7

[0151] This embodiment provides a method for preparing a coated modified iron-copper-manganese based precursor, in addition to adjusting the ratio of ferrous ions to manganese ions in the iron-manganese mixed salt solution and adjusting the flow rate of the iron-manganese mixed salt solution and the copper complex solution, so that the final product obtained in step (1) is Cu 0.3 Fe 0.35 Mn 0.35 Except for (OH)2, the rest are the same as in Example 1.

[0152] Comparative Example 1

[0153] This comparative example provides a method for preparing a coated modified iron-copper-manganese based precursor, in addition to adjusting the ratio of ferrous ions to manganese ions in the iron-manganese mixed salt solution and adjusting the flow rate of the iron-manganese mixed salt solution and the copper complex solution, so that the final product obtained in step (1) is Cu 0.4 Fe 0.3 Mn 0.3 Except for (OH)2, the rest are the same as in Example 1.

[0154] Comparative Example 2

[0155] This comparative example provides a method for preparing a coated modified iron-copper-manganese based precursor, in addition to adjusting the ratio of ferrous ions to manganese ions in the iron-manganese mixed salt solution and adjusting the flow rate of the iron-manganese mixed salt solution and the copper complex solution, so that the final product obtained in step (1) is Cu 0.2 Fe 0.6 Mn 0.2 Except for (OH)2, the rest are the same as in Example 1.

[0156] Comparative Example 3

[0157] This comparative example provides a method for preparing a coated modified iron-copper-manganese based precursor, in addition to adjusting the ratio of ferrous ions to manganese ions in the iron-manganese mixed salt solution and adjusting the flow rate of the iron-manganese mixed salt solution and the copper complex solution, so that the final product obtained in step (1) is Cu 0.2 Fe 0.2 Mn 0.6 Except for (OH)2, the rest are the same as in Example 1.

[0158] Comparative Example 4

[0159] This comparative example provides a method for preparing a coated and modified iron-copper-manganese-based precursor, which comprises the following steps:

[0160] (1) Under nitrogen atmosphere, iron-manganese mixed salt solution, copper complex solution, precipitant solution and complexing agent solution are added to the bottom liquid to carry out coprecipitation reaction. After the coprecipitation reaction reaches the target particle size D50 of 4 μm, the feeding is stopped, and the mixture is allowed to stand for aging. After conventional washing, centrifugation and drying, Cu 0.2 Fe 0.3 Mn 0.5 (OH)2;

[0161] The base liquid is a combination of water, ammonia water and sodium hydroxide solution, the pH value of the base liquid is 10, and the concentration of the complexing agent is 3.5g / L;

[0162] The metal salts in the iron-manganese mixed salt solution include ferrous sulfate and manganese sulfate, and the total concentration of ferrous ions and manganese ions is 0.8 mol / L;

[0163] The copper complex solution is a combination of 0.3 mol / L copper sulfate solution and 0.6 mol / L ammonia water;

[0164] The precipitant solution is sodium hydroxide solution, and the complexing agent solution is ammonia water;

[0165] The amount of iron-manganese mixed salt solution and copper complex solution added is such that the final product is Cu 0.2 Fe 0.3 Mn 0.5 (OH)2;

[0166] The amounts of the precipitant solution and the complexing agent solution were controlled so that the pH value of the coprecipitation reaction was 9.5, the ammonia concentration was 3 g / L, the temperature was 48° C., and the stirring speed was 400 rpm;

[0167] (2) Under a nitrogen atmosphere, the zirconium source solution, the precipitant solution, and the complexing agent solution are continuously added to the base liquid to carry out a coating reaction. The coating reaction is stopped after the target particle size D50 reaches 6.5 μm, and the particles are allowed to stand for 6 hours. After conventional washing, centrifugation, and drying, the coated and modified iron-copper-manganese-based precursor is obtained.

[0168] The zirconium source solution is a sulfuric acid solution of zirconium sulfate, the concentration of zirconium sulfate is 0.1 mol / L, and the pH value is 3;

[0169] The precipitant solution is sodium hydroxide solution, and the complexing agent solution is ammonia water;

[0170] The amounts of the precipitant solution and the complexing agent solution were controlled so that the pH value of the coating reaction was 11, the ammonia concentration was 4 g / L, the temperature was 58°C, and the stirring speed was 800 rpm;

[0171] In the obtained coated and modified iron-copper-manganese-based precursor, the coating amount of zirconium is 2000 ppm.

[0172] Comparative Example 5

[0173] This comparative example provides a method for preparing a coated and modified iron-copper-manganese-based precursor, which comprises the following steps:

[0174] (1) Under nitrogen atmosphere, iron-manganese mixed salt solution, copper complex solution, precipitant solution and complexing agent solution are added to the bottom liquid to carry out coprecipitation reaction. After the coprecipitation reaction reaches the target particle size D50 of 4 μm, the feeding is stopped, and the mixture is allowed to stand for aging. After conventional washing, centrifugation and drying, Cu 0.2 Fe 0.3 Mn 0.5 (OH)2;

[0175] The base liquid is a combination of water, ammonia water and sodium hydroxide solution, the pH value of the base liquid is 10, and the concentration of the complexing agent is 3.5g / L;

[0176] The metal salts in the iron-manganese mixed salt solution include ferrous sulfate and manganese sulfate, and the total concentration of ferrous ions and manganese ions is 0.8 mol / L;

[0177] The copper complex solution is a combination of 0.3 mol / L copper sulfate solution and 0.6 mol / L ammonia water;

[0178] The precipitant solution is sodium hydroxide solution, and the complexing agent solution is ammonia water;

[0179] The amount of iron-manganese mixed salt solution and copper complex solution added is such that the final product is Cu 0.2 Fe 0.3 Mn 0.5 (OH)2;

[0180] The amounts of the precipitant solution and the complexing agent solution were controlled so that the pH value of the coprecipitation reaction was 9.5, the ammonia concentration was 3 g / L, the temperature was 48° C., and the stirring speed was 400 rpm;

[0181] (2) Under a nitrogen atmosphere, aluminum source solution, precipitant solution and complexing agent solution are continuously added to the base liquid to carry out coating reaction. The coating reaction is stopped after the target particle size D50 reaches 6.5 μm, and the particles are allowed to stand for 6 hours. After conventional washing, centrifugation and drying, the coated and modified iron-copper-manganese-based precursor is obtained.

[0182] The aluminum source solution is a mixture of 0.2 mol / L sodium metaaluminate solution and 0.3 mol / L ammonia water;

[0183] The precipitant solution is sodium hydroxide solution, and the complexing agent solution is ammonia water;

[0184] The amounts of the precipitant solution and the complexing agent solution were controlled so that the pH value of the coating reaction was 11, the ammonia concentration was 4 g / L, the temperature was 58°C, and the stirring speed was 800 rpm;

[0185] In the obtained coated and modified iron-copper-manganese-based precursor, the coating amount of aluminum is 2000 ppm.

[0186] Comparative Example 6

[0187] This comparative example provides a method for preparing a coated and modified iron-copper-manganese-based precursor, which is the same as Example 1 except that the zirconium source solution is replaced by a hafnium sulfate solution, and the coating amount of hafnium in the obtained coated and modified iron-copper-manganese-based precursor is 1000 ppm and the coating amount of aluminum is 1000 ppm.

[0188] Comparative Example 7

[0189] This comparative example provides a method for preparing a coated and modified iron-copper-manganese-based precursor, which is the same as Example 1 except that the aluminum source solution is replaced by a magnesium sulfate solution, and the coating amount of zirconium in the obtained coated and modified iron-copper-manganese-based precursor is 1000 ppm and the coating amount of magnesium is 1000 ppm.

[0190] Application Example 1

[0191] This application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0192] Sodium hydroxide was mixed with the coated and modified iron-copper-manganese-based precursor obtained in Example 1, wherein the molar ratio of sodium hydroxide to the coated and modified iron-copper-manganese-based precursor was 1.01:1, and calcined at 800° C. for 24 h to obtain a positive electrode material.

[0193] Application Example 2

[0194] This application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0195] Sodium hydroxide was mixed with the coated and modified iron-copper-manganese-based precursor obtained in Example 2, wherein the molar ratio of sodium hydroxide to the coated and modified iron-copper-manganese-based precursor was 1.01:1, and calcined at 800° C. for 24 h to obtain a positive electrode material.

[0196] Application Example 3

[0197] This application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0198] Sodium hydroxide was mixed with the coated and modified iron-copper-manganese-based precursor obtained in Example 3, wherein the molar ratio of sodium hydroxide to the coated and modified iron-copper-manganese-based precursor was 1.01:1, and calcined at 800° C. for 24 h to obtain a positive electrode material.

[0199] Application Example 4

[0200] This application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0201] Sodium hydroxide was mixed with the coated and modified iron-copper-manganese-based precursor obtained in Example 4, wherein the molar ratio of sodium hydroxide to the coated and modified iron-copper-manganese-based precursor was 1.01:1, and calcined at 800° C. for 24 h to obtain a positive electrode material.

[0202] Application Example 5

[0203] This application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0204] Sodium hydroxide was mixed with the coated and modified iron-copper-manganese-based precursor obtained in Example 5, wherein the molar ratio of sodium hydroxide to the coated and modified iron-copper-manganese-based precursor was 1.01:1, and calcined at 800° C. for 24 h to obtain a positive electrode material.

[0205] Application Example 6

[0206] This application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0207] Sodium hydroxide was mixed with the coated and modified iron-copper-manganese-based precursor obtained in Example 6, wherein the molar ratio of sodium hydroxide to the coated and modified iron-copper-manganese-based precursor was 1.01:1, and calcined at 800° C. for 24 h to obtain a positive electrode material.

[0208] Application Example 7

[0209] This application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0210] Sodium hydroxide was mixed with the coated and modified iron-copper-manganese-based precursor obtained in Example 7, wherein the molar ratio of sodium hydroxide to the coated and modified iron-copper-manganese-based precursor was 1.01:1, and calcined at 800° C. for 24 h to obtain a positive electrode material.

[0211] Application Example 8

[0212] This application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0213] Sodium hydroxide was mixed with the coated and modified iron-copper-manganese-based precursor obtained in Example 1, wherein the molar ratio of sodium hydroxide to the coated and modified iron-copper-manganese-based precursor was 1:1, and calcined at 400° C. for 48 h to obtain a positive electrode material.

[0214] Application Example 9

[0215] This application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0216] Sodium hydroxide was mixed with the coated and modified iron-copper-manganese-based precursor obtained in Example 1, wherein the molar ratio of sodium hydroxide to the coated and modified iron-copper-manganese-based precursor was 1.05:1, and calcined at 1300° C. for 12 h to obtain a positive electrode material.

[0217] Comparative Application Example 1

[0218] This comparative application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0219] Sodium hydroxide was mixed with the coated modified iron-copper-manganese-based precursor obtained in Comparative Example 1, wherein the molar ratio of sodium hydroxide to the coated modified iron-copper-manganese-based precursor was 1.01:1, and calcined at 800° C. for 24 h to obtain a positive electrode material.

[0220] Comparative Application Example 2

[0221] This comparative application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0222] Sodium hydroxide was mixed with the coated modified iron-copper-manganese-based precursor obtained in Comparative Example 2, wherein the molar ratio of sodium hydroxide to the coated modified iron-copper-manganese-based precursor was 1.01:1, and calcined at 800° C. for 24 h to obtain a positive electrode material.

[0223] Comparative Application Example 3

[0224] This comparative application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0225] Sodium hydroxide was mixed with the coated modified iron-copper-manganese-based precursor obtained in Comparative Example 3, wherein the molar ratio of sodium hydroxide to the coated modified iron-copper-manganese-based precursor was 1.01:1, and calcined at 800° C. for 24 h to obtain a positive electrode material.

[0226] Comparative Application Example 4

[0227] This comparative application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0228] Sodium hydroxide was mixed with the coated modified iron-copper-manganese-based precursor obtained in Comparative Example 4, wherein the molar ratio of sodium hydroxide to the coated modified iron-copper-manganese-based precursor was 1.01:1, and calcined at 800° C. for 24 h to obtain a positive electrode material.

[0229] Comparative Application Example 5

[0230] This comparative application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0231] Sodium hydroxide was mixed with the coated modified iron-copper-manganese-based precursor obtained in Comparative Example 5, wherein the molar ratio of sodium hydroxide to the coated modified iron-copper-manganese-based precursor was 1.01:1, and calcined at 800° C. for 24 h to obtain a positive electrode material.

[0232] Comparative Application Example 6

[0233] This comparative application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0234] Sodium hydroxide was mixed with the coated modified iron-copper-manganese-based precursor obtained in Comparative Example 6, wherein the molar ratio of sodium hydroxide to the coated modified iron-copper-manganese-based precursor was 1.01:1, and calcined at 800° C. for 24 h to obtain a positive electrode material.

[0235] Comparative Application Example 7

[0236] This comparative application example provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0237] Sodium hydroxide was mixed with the coated modified iron-copper-manganese-based precursor obtained in Comparative Example 7, wherein the molar ratio of sodium hydroxide to the coated modified iron-copper-manganese-based precursor was 1.01:1, and calcined at 800° C. for 24 h to obtain a positive electrode material.

[0238] Performance Characterization

[0239] The positive electrode materials provided in the above application examples and comparative application examples were respectively coated on aluminum foil with conductive carbon black SP and 5wt% polyvinylidene fluoride solution in a mass ratio of 8:1:1 to form a positive electrode sheet. A metal sodium sheet was used as the negative electrode, a Celgard2400 model separator was used as the diaphragm, and the electrolyte was 1 mol / L NaPF6 (the solvent was ethylene carbonate and diethyl carbonate, with a volume ratio of 1:1). After the battery was allowed to stand for 12 hours, the first discharge capacity, the capacity retention rate after 100 cycles, and the cycle capacity retention rate after 1000 cycles were measured on a Land CT2001A battery tester.

[0240] The test method for the first discharge capacity is as follows: charge at a constant current and constant voltage rate of 1C to 3.7V, and then discharge at a rate of 1C to 2V;

[0241] The test method for the capacity retention rate after 100 cycles is as follows: charge to 3.7V at a constant current and constant voltage rate of 1C, then discharge to 2V at a rate of 1C. After 100 cycles, record the discharge capacity. The ratio of the discharge capacity after 100 cycles to the initial discharge capacity is the capacity retention rate after 100 cycles.

[0242] The results are shown in Table 1.

[0243] Table 1

[0244] By comparing the data of Application Examples 1-3 with those of Application Examples 1-3, it can be found that the ratios of different elements are within a reasonable range. Too high a Cu content, too high a Mn content, or too high a Fe content will reduce the stability of the material, making it difficult to obtain a positive electrode material with suitable performance.

[0245] By comparing the data of application examples 4-7 with the data of application examples 1-5, it can be found that the coating of zirconium and aluminum has a synergistic effect. Coating one element alone or replacing zirconium or aluminum with another element will affect the electrochemical properties of the material.

[0246] In summary, the preparation method provided in this application utilizes a coprecipitation method to obtain Cu a Fe b Mn c (OH)2, and then continue to use the co-precipitation method to carry out the coating reaction to obtain a coated and modified iron-copper-manganese-based precursor coated with a zirconium source and an aluminum source, wherein the addition of zirconium can improve the stability of the positive electrode material in the high voltage area, and the addition of aluminum can improve the cyclability of the positive electrode material. The synergistic effect of zirconium and aluminum ensures the electrochemical properties of the obtained coated and modified iron-copper-manganese-based precursor; moreover, the preparation method provided in the present application is simple to operate, the obtained coating layer is uniform and the coating amount is controllable, and it is suitable for industrial production.

[0247] The above description is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Those skilled in the art should understand that any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing a coated modified iron-copper-manganese-based precursor, comprising the following steps: (1) Adding iron-manganese mixed salt solution, copper complex solution, precipitant solution and complexing agent solution to the base liquid to carry out coprecipitation reaction. After the coprecipitation reaction reaches the target particle size, Cu a Fe b Mn c (OH) 2 , where 0 <a≤0.3,0<b≤0.5,0<c≤0.5,a+b+c=1; (2) Continue to add zirconium source solution, aluminum source solution, precipitant solution and complexing agent solution to the base solution to carry out coating reaction. After the coating reaction reaches the target particle size, the reaction is stopped to obtain the coated and modified iron-copper-manganese-based precursor.

2. The preparation method according to claim 1, in, The pH value of the coprecipitation reaction in step (1) is 7-10; Optionally, the concentration of the complexing agent in the coprecipitation reaction in step (1) is 1-6 g / L; Optionally, the temperature of the coprecipitation reaction in step (1) is 30-60° C.; Optionally, the target particle size of the coprecipitation reaction in step (1) is D50 reaching 2-5 μm.

3. The preparation method according to claim 1 or 2, in, The coprecipitation reaction in step (1) is accompanied by a first stirring; Optionally, the first stirring speed is 150-500 rpm.

4. The preparation method according to any one of claims 1 to 3, in, The pH value of the coating reaction in step (2) is 10-12; Optionally, the concentration of the complexing agent in the coating reaction in step (2) is 0.5-6 g / L; Optionally, the temperature of the coating reaction in step (2) is 50-80°C; Optionally, the target particle size of the coating reaction in step (2) is D50 reaching 5-8 μm.

5. The preparation method according to any one of claims 1 to 4, in, The coating reaction in step (2) is accompanied by a second stirring; Optionally, the second stirring speed is 500-1000 rpm; Optionally, in the coated and modified iron-copper-manganese-based precursor, the coating amount of zirconium is 100-3000ppm; Optionally, in the coated modified iron-copper-manganese-based precursor, the coating amount of aluminum is 100-3000 ppm.

6. A coated and modified iron-copper-manganese-based precursor prepared by the preparation method according to any one of claims 1 to 5.

7. A method for preparing a positive electrode material comprises the following steps: The sodium salt is mixed with the coated and modified iron-copper-manganese-based precursor according to claim 6, and calcined to obtain the positive electrode material.

8. The preparation method according to claim 7, in, The sodium salt includes any one of sodium carbonate, sodium hydroxide or sodium nitrate, or a combination of at least two thereof; Optionally, the molar ratio of sodium in the sodium salt to the coated modified iron-copper-manganese-based precursor is (1-1.05):1; Optionally, the calcination temperature is 400-1300° C. and the calcination time is 12-48 hours.

9. A positive electrode material prepared by the preparation method according to claim 7 or 8.

10. A sodium ion battery comprising the coated and modified iron-copper-manganese-based precursor according to claim 6, or comprising the positive electrode material according to claim 9.

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