Method for regenerating lithium manganese iron phosphate material, lithium manganese iron phosphate material and battery

Abstract

The invention provides a method for regenerating a lithium iron manganese phosphate material, the lithium iron manganese phosphate material and a battery, and belongs to the technical field of batteries, the method for regenerating the lithium iron manganese phosphate material comprises the following steps: providing lithium iron manganese phosphate powder to be recycled; wherein the lithium manganese iron phosphate powder to be recycled comprises a material with a molecular formula of LiaFebMncPO4, a is more than 0 and less than 1, and b + c is more than 0 and less than 1; dispersing the to-be-recycled lithium manganese iron phosphate powder, tannic acid and thiourea into a solvent to obtain a first mixed solution; adding a lithium source and a manganese source into the first mixed solution to obtain a second mixed solution; and reacting the second mixed solution at 140-160 DEG C, and treating to obtain the regenerated lithium manganese iron phosphate material. According to the method for regenerating the lithium manganese iron phosphate material, the lithium manganese iron phosphate to be recycled does not need to be damaged, the reaction condition is mild, the energy consumption is reduced, the process difficulty is reduced, a large amount of waste water and waste gas cannot be generated, and the method has the advantages of being green, economical and environmentally friendly.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method for regenerating lithium iron manganese phosphate material, lithium iron manganese phosphate material and a battery. Background Art

[0002] In recent years, lithium-ion batteries made of lithium manganese iron phosphate (LMFP) cathode materials have been widely used in smart electronic devices, electric vehicles, and energy storage systems due to their advantages of low cost, long life, and high safety. However, lithium batteries have a certain life cycle, and lithium resources on the earth are limited. How to deal with a large number of waste lithium manganese iron phosphate batteries and how to recycle resources have become adjustments.

[0003] In the related art, waste lithium iron phosphate materials in lithium iron phosphate batteries are usually recovered by pyrolysis or wet methods, but these methods consume a lot of energy and also generate a lot of waste gas and wastewater. Summary of the invention

[0004] The embodiments of the present application provide a method for regenerating lithium iron manganese phosphate material, lithium iron manganese phosphate material and battery. The method for regenerating lithium iron manganese phosphate material can regenerate waste lithium iron manganese phosphate under mild conditions, reduce energy consumption and reduce the difficulty of regeneration.

[0005] In a first aspect, an embodiment of the present application provides a method for regenerating lithium iron manganese phosphate material, comprising:

[0006] Provide lithium iron manganese phosphate powder to be recycled; wherein the lithium iron manganese phosphate powder to be recycled includes a molecular formula of Li a Fe b Mn c PO4 material, 0<a<1, 0<b+c<1;

[0007] Dispersing the lithium manganese iron phosphate powder to be recovered, tannic acid and thiourea in a solvent to obtain a first mixed solution;

[0008] adding a lithium source and a manganese source into the first mixed solution to obtain a second mixed solution;

[0009] The second mixed solution is reacted at 140° C.-160° C. to obtain a regenerated lithium manganese iron phosphate material.

[0010] In some embodiments, the mass ratio of the lithium manganese iron phosphate powder to be recovered to tannic acid and thiourea is (4-7): (2-4): (1-3).

[0011] In some embodiments, after dispersing the lithium manganese iron phosphate powder to be recovered, tannic acid and thiourea in a solvent, the method further comprises:

[0012] Analyzing the molar contents of lithium, iron and manganese in the first mixed solution to obtain content analysis results;

[0013] Adding a lithium source and a manganese source into the first mixed solution to obtain a second mixed solution, comprising:

[0014] According to the content analysis results, a lithium source and a manganese source are added to the first mixed solution to obtain a second mixed solution, so that the molar contents of lithium, iron and manganese in the second mixed solution satisfy: C1 = C2 + C3;

[0015] Wherein, C1 represents the molar content of lithium element in the second mixed solution, C2 represents the molar content of iron element in the second mixed solution, and C3 represents the molar content of manganese element in the second mixed solution.

[0016] In some embodiments, the solid content in the first mixed solution is 1%-10%.

[0017] In some embodiments, the lithium source comprises lithium acetate;

[0018] And / or, the manganese source comprises manganese acetate.

[0019] In some embodiments, the second mixed solution is reacted at 140° C.-160° C., comprising:

[0020] reacting the second mixed solution at 140° C.-160° C. to obtain a first precursor;

[0021] The carbon source and the first precursor are mixed and then ball-milled to obtain a second precursor;

[0022] The second precursor is sintered under a protective atmosphere to obtain a regenerated lithium manganese iron phosphate material.

[0023] In some embodiments, the second mixed solution is reacted at 140° C.-160° C., comprising:

[0024] The second mixed solution was reacted at 140°C-160°C for 5h-7h.

[0025] In some embodiments, the carbon source comprises glucose;

[0026] And / or, the mass ratio of the carbon source to the first precursor is 1:(5-10).

[0027] In some embodiments, the carbon source and the first precursor are mixed and then ball milled, comprising:

[0028] mixing a carbon source and a first precursor to obtain a mixture;

[0029] The mixture was ball-milled at a rotation speed of 500 rpm for 4 h-6 h and dried to obtain a second precursor.

[0030] In some embodiments, sintering the second precursor comprises:

[0031] The second precursor is sintered at 600°C-850°C for 4h-5h.

[0032] In a second aspect, an embodiment of the present application provides a lithium iron manganese phosphate material obtained by the method for regenerating the lithium iron manganese phosphate material as described above.

[0033] In a third aspect, an embodiment of the present application provides a battery comprising the lithium manganese iron phosphate material as described above.

[0034] Beneficial effects of the embodiments of the present application:

[0035] In an embodiment of the present application, a method for regenerating lithium iron manganese phosphate material includes: forming a first mixed solution by mixing lithium iron manganese phosphate powder to be recovered with tannic acid and thiourea phenolic acid in a solvent, and then adding a lithium source and a manganese source to the first mixed solution to form a second mixed solution, and reacting the second mixed solution under the conditions of 140°C-160°C, and then post-processing to obtain a regenerated lithium iron manganese phosphate material. In this process, tannic acid with a strong adsorption effect and thiourea with a reducing property can adhere to the surface of the lithium iron manganese phosphate powder to be recovered, and then can reduce the high-valent iron and manganese elements in the lithium iron manganese phosphate to be recovered under the conditions of 140°C-160°C, and the added lithium source and manganese source can supplement the lithium and manganese elements lost in the lithium iron manganese phosphate powder to be recovered, thereby obtaining a regenerated lithium iron manganese phosphate material. The method for regenerating lithium iron manganese phosphate material provided in the embodiment of the present application does not require the destruction of the lithium iron manganese phosphate to be recovered, has mild reaction conditions, reduces energy consumption, reduces process difficulty, and does not generate a large amount of wastewater and waste gas, and has the advantages of green economy and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 It is a comparative analysis chart of the rate performance of Example 6 of the present application and Comparative Example 1. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0039] In a first aspect, an embodiment of the present application provides a method for regenerating lithium iron manganese phosphate material, comprising:

[0040] Provide lithium iron manganese phosphate powder to be recycled; wherein the lithium iron manganese phosphate powder to be recycled includes a molecular formula of Li a Fe b Mn c PO4 material, 0<a<1, 0<b+c<1;

[0041] Dispersing the lithium manganese iron phosphate powder to be recovered, tannic acid and thiourea in a solvent to obtain a first mixed solution;

[0042] adding a lithium source and a manganese source into the first mixed solution to obtain a second mixed solution;

[0043] The second mixed solution is reacted at 140° C.-160° C. and treated to obtain a regenerated lithium manganese iron phosphate material.

[0044] Providing lithium manganese iron phosphate powder to be recycled can improve the dispersion performance and make the reaction more complete. The lithium manganese iron phosphate powder to be recycled includes a molecular formula of Li a Fe b Mn c PO4 material, 0<a<1, 0<b+c<1. That is, there is a partial loss of lithium and manganese in the lithium manganese iron phosphate powder to be recycled, and the valence state of at least part of the iron and manganese elements increases, resulting in its performance being affected. 76 H 52 O 46), thiourea (CH4N2S), tannic acid has a strong adsorption effect and can be adsorbed on the surface of the lithium iron manganese phosphate powder to be recovered, and thiourea has a strong reducing property. It is attached to the surface of the lithium iron manganese phosphate powder through tannic acid, and the structure of the lithium iron manganese phosphate powder to be recovered does not need to be further destroyed in this process. Then, a lithium source and a manganese source are added to the first mixed solution. The tannic acid and thiourea adsorbed on the surface of the lithium iron manganese phosphate powder to be recovered can reduce the high-valent iron and manganese elements in the lithium iron manganese phosphate powder to be recovered under the condition of 140°C-160°C. The added lithium source and manganese source can replenish the lithium and manganese elements lost by the lithium iron manganese phosphate powder to be recovered during use, so that the element ratio and valence state meet the requirements of lithium iron manganese phosphate again. After post-treatment, a regenerated lithium iron manganese phosphate material is obtained. Among them, the post-treatment after the reaction can include filtering, washing, drying, sintering, crushing and other process processes, and the regenerated lithium iron manganese phosphate material that meets the process requirements can be obtained, which is not specifically limited here.

[0045] In some embodiments, the mass ratio of the lithium manganese iron phosphate powder to be recovered to tannic acid and thiourea is (4-7): (2-4): (1-3).

[0046] Tannic acid has abundant functional groups such as phenolic hydroxyl and carboxyl groups, which enable it to interact with the lithium manganese iron phosphate to be recovered through hydrogen bonds, ionic bonds or coordination bonds, thereby achieving adsorption. In addition, the cross-linking and polymerization between tannic acid molecules can also enhance its adsorption capacity. Tannic acid also has reducing properties and can also participate in the reduction reaction of high-valent lithium and manganese elements in the lithium manganese iron phosphate to be recovered. By setting the mass ratio of the lithium manganese iron phosphate to be recovered to tannic acid to (4-7): (2-4), the adsorption capacity and adsorption rate of tannic acid can be guaranteed, and the phenomenon of increased intermolecular interactions caused by excessive addition of tannic acid, which reduces the adsorption effect, can be avoided.

[0047] Illustratively, the mass ratio of the lithium manganese iron phosphate powder to be recovered to tannic acid can be 4:2, 4:3, 4:4, 5:2, 5:3, 5:4, 6:2, 6:3, 6:4, 7:2, 7:3 or 7:4.

[0048] Thiourea has strong reducing properties and can reduce a variety of metal ions, including iron ions and manganese ions, and reduce high-valent iron ions and manganese ions from high-valent states to low-valent states. By setting the mass ratio of the lithium manganese iron phosphate powder to be recycled to thiourea to (4-7): (1-3), it can be ensured that thiourea can fully adhere to the surface of the lithium manganese iron phosphate powder to be recycled, which is helpful for the subsequent in-situ reduction of the high-valent iron and manganese elements in the lithium manganese iron phosphate powder to be recycled.

[0049] Illustratively, the mass ratio of the lithium manganese iron phosphate powder to be recovered to thiourea can be 4:1, 4:2, 4:3, 5:1, 5:2, 5:3, 6:1, 6:2, 6:3, 7:1, 7:2 or 7:3.

[0050] In some embodiments, after dispersing the lithium manganese iron phosphate powder to be recovered, tannic acid and thiourea in a solvent, the method further comprises:

[0051] Analyzing the molar contents of lithium, iron and manganese in the first mixed solution to obtain content analysis results;

[0052] Adding a lithium source and a manganese source into the first mixed solution to obtain a second mixed solution, comprising:

[0053] According to the content analysis results, a lithium source and a manganese source are added to the first mixed solution to obtain a second mixed solution, so that the molar contents of lithium, iron and manganese in the second mixed solution satisfy: C1 = C2 + C3;

[0054] Wherein, C1 represents the molar content of lithium element in the second mixed solution, C2 represents the molar content of iron element in the second mixed solution, and C3 represents the molar content of manganese element in the second mixed solution.

[0055] When lithium manganese iron phosphate is used as the positive electrode material of the battery, the lithium ions are deintercalated and intercalated between the positive and negative electrodes during the charge and discharge process of the battery. During this process, some lithium ions may be lost due to various reasons (such as slight changes in the internal structure of the battery, electrolyte decomposition, etc.), and the electrolyte may also decompose during the operation of the battery to produce some by-products, which may react with lithium ions and cause lithium loss. During the battery cycle, manganese will gradually precipitate from the positive electrode material, and some manganese will dissolve in the electrolyte to form manganese ions, which will lead to the loss of lithium and manganese elements in lithium manganese iron phosphate.

[0056] The embodiment of the present application can determine the content of lithium and manganese lost in the lithium iron manganese phosphate powder to be recycled by analyzing the molar content of lithium, iron and manganese in the lithium iron manganese phosphate powder to be recycled, thereby adding lithium source and manganese source in appropriate proportions.

[0057] According to the content analysis results, a lithium source and a manganese source are added in a suitable proportion to the first mixed solution to obtain a second mixed solution, so that the contents of lithium, iron and manganese in the second mixed solution satisfy: C1=C2+C3.

[0058] The molecular formula of lithium manganese iron phosphate is LiFe x Mn 1-xPO4, that is, when the molar content of lithium (Li) is 1 mol, the total molar content of iron (Fe) and manganese (Mn) should also be 1 mol. By making the content of each element satisfy the above formula, the ratio of lithium, iron and manganese in the second mixed solution meets the molecular formula requirements of lithium iron manganese phosphate, and then the regenerated lithium iron manganese phosphate material that meets the requirements is obtained through the reaction, which improves the utilization rate of lithium source and manganese source, reduces material waste and saves costs.

[0059] It is understandable that the ratio of the added lithium source and the manganese source can be reasonably adjusted according to the molecular formula of the desired regenerated lithium manganese iron phosphate material. 0.4 Mn 0.6 When regenerating lithium manganese iron phosphate material from PO4, C2:C3=4:6. When you want to get a molecular formula of LiFe 0.5 Mn 0.5 When regenerating lithium manganese iron phosphate material with PO4, C2:C3=5:5.

[0060] In some embodiments, the solid content in the first mixed solution is 1%-10%. By setting the solid content in the first mixed solution to 1%-10%, the dispersion performance of the lithium manganese iron phosphate powder to be recovered, tannic acid and thiourea in the first mixed solution can be ensured, so that the first mixed solution has a suitable viscosity, which helps to improve the efficiency of the subsequent reduction reaction and ensure the reduction effect.

[0061] In some embodiments, the lithium source includes lithium acetate. Lithium acetate has high reactivity and can react with tannic acid and thiourea at a lower reaction temperature to improve the recovery efficiency. When lithium acetate is used as a lithium source, less by-products are produced during the reaction and are easy to handle, which can reduce the impact on the environment during the recovery process.

[0062] It is understandable that the lithium source may also be other lithium salts, such as lithium chloride, lithium sulfate, etc., which are soluble in solvents and can undergo reduction reactions with tannic acid and thiourea.

[0063] In some embodiments, the manganese source includes manganese acetate. Manganese acetate also has high reactivity and can react with tannic acid and thiourea at a lower reaction temperature to improve recovery efficiency. The cost of manganese acetate is low, which helps to reduce costs. Using manganese acetate as a manganese source, the by-products produced during the reaction are less and easy to handle, which can reduce the impact on the environment during the recovery process.

[0064] It is understandable that the manganese source may also be other manganese salts, such as manganese sulfate, manganese chloride, etc., which are soluble in solvents and can undergo reduction reactions with tannic acid and thiourea.

[0065] In some embodiments, a lithium source and a manganese source are added to a first mixed solution to obtain a second mixed solution, comprising:

[0066] A lithium source and a manganese source are added to the first mixed solution, ultrasonically dispersed for 30 minutes, and then stirred for 30 minutes to 60 minutes to obtain a second mixed solution.

[0067] The lithium source and the manganese source are fully dispersed in the second mixed solution by ultrasonic dispersion and stirring, so as to improve the reaction efficiency and ensure the reaction uniformity.

[0068] In some embodiments, the second mixed solution is reacted at 140° C.-160° C., comprising:

[0069] reacting the second mixed solution at 140° C.-160° C. to obtain a first precursor;

[0070] The carbon source and the first precursor are mixed and then ball-milled to obtain a second precursor;

[0071] The second precursor is sintered under a protective atmosphere to obtain a regenerated lithium manganese iron phosphate material.

[0072] After the second mixed solution is reacted at 140°C-160°C, the lithium ions in the lithium source are reduced to lithium atoms, the manganese ions are reduced to manganese atoms, and are combined with the lithium iron manganese phosphate powder to be recovered to form a first precursor with an element ratio that meets the requirements. After the carbon source and the first precursor are ball-milled, the first precursor and the carbon source can be further crushed and fully mixed to obtain a second precursor. Under a protective atmosphere, the second precursor is sintered to form a carbon coating layer on the carbon source. At the same time, the thiourea attached to the surface of the lithium iron manganese phosphate powder to be recovered during the reaction can provide nitrogen elements, thereby forming a nitrogen-doped carbon coating layer, which can improve the cycle stability of the regenerated lithium iron manganese phosphate material.

[0073] In some embodiments, the second mixed solution is reacted at 140° C.-160° C., comprising:

[0074] The second mixed solution was reacted at 140°C-160°C for 5h-7h.

[0075] That is, the second mixed solution is reacted for 5 hours to 7 hours at a temperature of 140° C. to 160° C., so that the lithium source and manganese source added to the second mixed solution can be fully reduced and energy consumption can be reduced.

[0076] For example, the reaction temperature may be set to 140° C., 145° C., 150° C., 155° C., or 160° C. The reaction time may be set to 5 h, 5.5 h, 6 h, 6.5 h, or 7 h.

[0077] In some embodiments, the carbon source includes glucose. When glucose is carbonized and decomposed at high temperature, it can form a dense carbon network, which is tightly wrapped on the surface of lithium manganese iron phosphate to construct a conductive network and improve electronic conductivity. Glucose as a carbon source can improve the uniformity of the coating, provide a stable chemical and electrochemical reaction interface, and inhibit the dissolution of elements such as manganese. In addition, glucose has a wide range of sources and low cost, which helps to reduce costs.

[0078] In addition, carbon sources can also be sucrose, amino acids, starch, cellulose, etc.

[0079] In some embodiments, the mass ratio of the carbon source to the first precursor is 1:(5-10). By controlling the mass ratio of the carbon source to the first precursor within the above range, it is possible to ensure that the carbon source forms a conductive network after sintering and improve the structural stability of the formed coating layer. Reasonable ratios also help to improve energy density and reduce cost investment while ensuring safety.

[0080] Illustratively, the mass ratio of the carbon source to the first precursor may be 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0081] In some embodiments, the carbon source and the first precursor are mixed and then ball milled, comprising:

[0082] mixing a carbon source and a first precursor to obtain a mixture;

[0083] The mixture was ball-milled at a rotation speed of 500 rpm for 4 h-6 h and dried to obtain a second precursor.

[0084] By ball milling at a rotation speed of 500 rpm, the carbon source and the first precursor can be fully mixed, and the carbon source and the first precursor can be refined during the mixing process, and the problem of excessive heat caused by excessive rotation speed can be avoided. Setting the ball milling time to 4h-6h can balance the mixing degree of the raw materials and energy consumption, ensuring that the carbon source and the first precursor are mixed evenly, while reducing energy consumption and improving efficiency.

[0085] Exemplarily, the ball milling time can be set to 4 h, 4.5 h, 5 h, 5.5 h or 6 h.

[0086] In some embodiments, sintering the second precursor comprises:

[0087] The second precursor is sintered at 600°C-850°C for 4h-5h.

[0088] By setting the sintering temperature to 600℃-850℃, the carbon source can be fully carbonized and closely combined with the lithium iron manganese phosphate particles in the second precursor to form a uniform coating layer. In this temperature range, the lithium iron manganese phosphate particles can maintain good stability and crystal structure. Setting the sintering time to 4h-5h can balance the formation of the coating layer and energy consumption, while ensuring the formation of a uniform coating layer and maintaining high production efficiency.

[0089] For example, the sintering temperature may be 600° C., 650° C., 700° C., 750° C., 800° C., or 850° C. The sintering time may be 4 h, 4.5 h, or 5 h.

[0090] In addition, since thiourea is added as a reducing agent in the method for regenerating lithium iron manganese phosphate material provided in the embodiment of the present application, and thiourea is attached to the surface of the lithium iron manganese phosphate powder to be recycled. Nitrogen elements can be provided during the sintering process to form a nitrogen-doped carbon coating, which can introduce additional electronic states, thereby enhancing conductivity, and nitrogen doping can also reduce the energy barrier of the carbon layer, provide more channels for the migration of lithium ions, and ensure the rapid transmission of lithium ions. Compared with ordinary carbon coatings, nitrogen-doped carbon coatings can also optimize the electronic structure of the material, improve energy storage capacity, and thus improve the energy density and capacity of the battery. The nitrogen-doped carbon coating can also improve the overall structural strength, inhibit volume expansion, improve thermal stability and other effects.

[0091] In a second aspect, an embodiment of the present application provides a lithium iron manganese phosphate material obtained by the method for regenerating the lithium iron manganese phosphate material as described above.

[0092] The lithium iron manganese phosphate material provided in the embodiment of the present application has all the advantages of the method for regenerating the lithium iron manganese phosphate material, which will not be repeated here.

[0093] In a third aspect, an embodiment of the present application provides a battery comprising the lithium manganese iron phosphate material as described above.

[0094] The battery provided in the embodiment of the present application has all the advantages of the method for regenerating lithium manganese iron phosphate material, which will not be repeated here.

[0095] The following examples are further described in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods in the following examples that do not specify specific conditions are usually based on the conditions recommended by the manufacturer.

[0096] Example 1

[0097] (1) crushing the recovered lithium iron manganese phosphate material to obtain the lithium iron manganese phosphate material to be recovered;

[0098] (2) adding 6 g of the lithium manganese iron phosphate material to be recovered, 3 g of tannic acid and 1 g of thiourea into a 200 mL reactor, adding 100 mL of deionized water, and mixing to obtain a first mixed solution;

[0099] (3) analyzing the molar contents of lithium, iron, and manganese in the first mixed solution to obtain content analysis results;

[0100] (4) According to the analysis results, lithium acetate and manganese acetate in a suitable ratio were added to the first mixed solution, and after ultrasonic dispersion for 30 minutes, the mixture was stirred for 45 minutes to obtain a second mixed solution, and the molar contents of lithium, iron and manganese in the second mixed solution satisfied: C1 = C2 + C3, and the molar contents of iron and manganese satisfied: C2:C3 = 6:4;

[0101] (5) The second mixed solution is placed in an oven and reacted at 150° C. for 6 hours. After cooling, the mixture is filtered and the filtrate is washed to obtain a regenerated lithium manganese iron phosphate material.

[0102] Example 2

[0103] (1) crushing the recovered lithium iron manganese phosphate material to obtain the lithium iron manganese phosphate material to be recovered;

[0104] (2) adding 4 g of the lithium manganese iron phosphate material to be recovered, 2 g of tannic acid and 3 g of thiourea into a reactor with a capacity of 200 mL, adding 140 mL of deionized water, and mixing to obtain a first mixed solution;

[0105] (3) analyzing the molar contents of lithium, iron, and manganese in the first mixed solution to obtain content analysis results;

[0106] (4) According to the analysis results, lithium acetate and manganese acetate in a suitable ratio were added to the first mixed solution, and after ultrasonic dispersion for 30 minutes, the mixture was stirred for 30 minutes to obtain a second mixed solution, and the molar contents of lithium, iron and manganese in the second mixed solution satisfied: C1 = C2 + C3, and the molar contents of iron and manganese satisfied: C2:C3 = 6:4;

[0107] (5) The second mixed solution is placed in an oven and reacted at 140° C. for 5 hours. After cooling, the mixture is filtered and the filtrate is washed to obtain a regenerated lithium manganese iron phosphate material.

[0108] Example 3

[0109] (1) crushing the recovered lithium iron manganese phosphate material to obtain the lithium iron manganese phosphate material to be recovered;

[0110] (2) adding 7 g of the lithium manganese iron phosphate material to be recovered, 4 g of tannic acid and 3 g of thiourea into a reactor with a capacity of 200 mL, adding 140 mL of deionized water, and mixing to obtain a first mixed solution;

[0111] (3) analyzing the molar contents of lithium, iron, and manganese in the first mixed solution to obtain content analysis results;

[0112] (4) According to the analysis results, lithium acetate and manganese acetate in a suitable ratio were added to the first mixed solution, and after ultrasonic dispersion for 30 minutes, the mixture was stirred for 60 minutes to obtain a second mixed solution, and the molar contents of lithium, iron and manganese in the second mixed solution satisfied: C1 = C2 + C3, and the molar contents of iron and manganese satisfied: C2:C3 = 4:6;

[0113] (5) The second mixed solution is placed in an oven and reacted at 160° C. for 7 hours. After cooling, the mixture is filtered and the filtrate is washed to obtain a regenerated lithium manganese iron phosphate material.

[0114] Example 4

[0115] (1) crushing the recovered lithium iron manganese phosphate material to obtain the lithium iron manganese phosphate material to be recovered;

[0116] (2) adding 7 g of the lithium manganese iron phosphate material to be recovered, 2 g of tannic acid and 1 g of thiourea into a 200 mL reactor, adding 100 mL of deionized water, and mixing to obtain a first mixed solution;

[0117] (3) analyzing the molar contents of lithium, iron, and manganese in the first mixed solution to obtain content analysis results;

[0118] (4) According to the analysis results, lithium acetate and manganese acetate in a suitable ratio were added to the first mixed solution, and after ultrasonic dispersion for 30 minutes, the mixture was stirred for 45 minutes to obtain a second mixed solution, and the molar contents of lithium, iron and manganese in the second mixed solution satisfied: C1 = C2 + C3, and the molar contents of iron and manganese satisfied: C2:C3 = 4:6;

[0119] (5) The second mixed solution is placed in an oven and reacted at 150° C. for 6 hours. After cooling, the mixture is filtered and the filtrate is washed to obtain a regenerated lithium manganese iron phosphate material.

[0120] Example 5

[0121] (1) crushing the recovered lithium iron manganese phosphate material to obtain the lithium iron manganese phosphate material to be recovered;

[0122] (2) adding 4 g of the lithium manganese iron phosphate material to be recovered, 4 g of tannic acid and 3 g of thiourea into a reactor with a capacity of 200 mL, adding 100 mL of deionized water, and mixing to obtain a first mixed solution;

[0123] (3) analyzing the molar contents of lithium, iron, and manganese in the first mixed solution to obtain content analysis results;

[0124] (4) According to the analysis results, lithium acetate and manganese acetate in a suitable ratio were added to the first mixed solution, and after ultrasonic dispersion for 30 minutes, the mixture was stirred for 45 minutes to obtain a second mixed solution, and the molar contents of lithium, iron and manganese in the second mixed solution satisfied: C1 = C2 + C3, and the molar contents of iron and manganese satisfied: C2:C3 = 4:6;

[0125] (5) The second mixed solution is placed in an oven and reacted at 150° C. for 6 hours. After cooling, the mixture is filtered and the filtrate is washed to obtain a regenerated lithium manganese iron phosphate material.

[0126] Example 6

[0127] (1) crushing the recovered lithium iron manganese phosphate material to obtain the lithium iron manganese phosphate material to be recovered;

[0128] (2) adding 6 g of the lithium manganese iron phosphate material to be recovered, 3 g of tannic acid and 1 g of thiourea into a 200 mL reactor, adding 100 mL of deionized water, and mixing to obtain a first mixed solution;

[0129] (3) analyzing the molar contents of lithium, iron, and manganese in the first mixed solution to obtain content analysis results;

[0130] (4) According to the analysis results, lithium acetate and manganese acetate in a suitable ratio were added to the first mixed solution, and after ultrasonic dispersion for 30 minutes, the mixture was stirred for 45 minutes to obtain a second mixed solution, and the molar contents of lithium, iron and manganese in the second mixed solution satisfied: C1 = C2 + C3, and the molar contents of iron and manganese satisfied: C2:C3 = 6:4;

[0131] (5) placing the second mixed solution in an oven, reacting at 150° C. for 6 h, cooling, filtering, and washing the filtrate to obtain a first precursor;

[0132] (6) Glucose and the first precursor were added into a ball mill at a ratio of 1:7, and anhydrous ethanol was added, and the mixture was ball milled on a planetary ball mill at a speed of 500 rpm for 5 h. After drying, a second precursor was obtained.

[0133] (7) Under a nitrogen protective atmosphere, the second precursor is sintered at 700° C. for 6 hours to obtain a regenerated lithium manganese iron phosphate material.

[0134] Example 7

[0135] (1) crushing the recovered lithium iron manganese phosphate material to obtain the lithium iron manganese phosphate material to be recovered;

[0136] (2) adding 6 g of the lithium manganese iron phosphate material to be recovered, 3 g of tannic acid and 1 g of thiourea into a 200 mL reactor, adding 100 mL of deionized water, and mixing to obtain a first mixed solution;

[0137] (3) analyzing the molar contents of lithium, iron, and manganese in the first mixed solution to obtain content analysis results;

[0138] (4) According to the analysis results, lithium acetate and manganese acetate in a suitable ratio were added to the first mixed solution, and after ultrasonic dispersion for 30 minutes, the mixture was stirred for 45 minutes to obtain a second mixed solution, and the molar contents of lithium, iron and manganese in the second mixed solution satisfied: C1 = C2 + C3, and the molar contents of iron and manganese satisfied: C2:C3 = 6:4;

[0139] (5) placing the second mixed solution in an oven, reacting at 150° C. for 6 h, cooling, filtering, and washing the filtrate to obtain a first precursor;

[0140] (6) Glucose and the first precursor were added into a ball mill at a ratio of 1:5, and anhydrous ethanol was added, and the mixture was ball milled on a planetary ball mill at a speed of 500 rpm for 4 h. After drying, a second precursor was obtained.

[0141] (7) Under a nitrogen protective atmosphere, the second precursor is sintered at 600° C. for 4 h to obtain a regenerated lithium manganese iron phosphate material.

[0142] Example 8

[0143] (1) crushing the recovered lithium iron manganese phosphate material to obtain the lithium iron manganese phosphate material to be recovered;

[0144] (2) adding 6 g of the lithium manganese iron phosphate material to be recovered, 3 g of tannic acid and 1 g of thiourea into a reactor with a capacity of 200 mL, adding 100 mL of deionized water, and mixing to obtain a first mixed solution;

[0145] (3) analyzing the molar contents of lithium, iron, and manganese in the first mixed solution to obtain content analysis results;

[0146] (4) According to the analysis results, lithium acetate and manganese acetate in a suitable ratio were added to the first mixed solution, and after ultrasonic dispersion for 30 minutes, the mixture was stirred for 45 minutes to obtain a second mixed solution, and the molar contents of lithium, iron and manganese in the second mixed solution satisfied: C1 = C2 + C3, and the molar contents of iron and manganese satisfied: C2:C3 = 6:4;

[0147] (5) placing the second mixed solution in an oven, reacting at 150° C. for 6 h, cooling, filtering, and washing the filtrate to obtain a first precursor;

[0148] (6) Glucose and the first precursor were added into a ball mill at a ratio of 1:10, and anhydrous ethanol was added, and the mixture was ball milled on a planetary ball mill at a speed of 500 rpm for 6 h. After drying, a second precursor was obtained.

[0149] (7) Under a nitrogen protective atmosphere, the second precursor is sintered at 850° C. for 8 h to obtain a regenerated lithium manganese iron phosphate material.

[0150] Comparative Example 1

[0151] (1) crushing the recovered lithium iron manganese phosphate material to obtain the lithium iron manganese phosphate material to be recovered;

[0152] (2) adding 30 g of the lithium manganese iron phosphate material to be recovered into 100 mL of deionized water, stirring continuously at a speed of 30 r / min and preheating to 30° C. to obtain a first mixed solution;

[0153] (3) slowly adding 200 mL of the H3PO4-H2O2 mixed solution to the first mixed solution obtained in step (1) to obtain a second mixed solution; wherein the mass ratio of H3PO4 to the lithium manganese iron phosphate material to be recovered is 1.1:1, and the mass ratio of H3PO4 to the lithium manganese iron phosphate material to be recovered is 1.2:1;

[0154] (4) adding a 0.3 g / mL NaOH solution dropwise to the second mixed solution obtained in step (2), adjusting the pH to 3.5, filtering to obtain a first mixture containing FePO4 and Mn3(PO4)2, and a third mixed solution after removing the mixture, and confirming the molar content of iron and manganese in the first mixture by ICP analysis;

[0155] (5) adding a 0.3 g / mL NaOH solution to the third mixed solution obtained in step (3), adjusting the pH to 8.0-10.0, filtering again to obtain a second mixture containing Li3PO4, and confirming the molar content of lithium in the second mixture by ICP analysis;

[0156] (6) mixing the first mixture, the second mixture and manganese acetate in proportion to obtain a third mixture, wherein Li:Fe:Mn=1:0.6:0.4 in the third mixture, and then adding the third mixture into a ball mill, adding anhydrous ethanol into the ball mill, and ball milling for 5 h on a planetary ball mill at a rotation speed of 500 rpm. After drying, sintering at 450° C. for 5 h under a nitrogen protective atmosphere to obtain a first precursor;

[0157] (7) Glucose and the first precursor were added into a ball mill at a ratio of 1:7, and anhydrous ethanol was added, and the mixture was ball milled on a planetary ball mill at a speed of 500 rpm for 5 h. After drying, a second precursor was obtained.

[0158] (8) Under a nitrogen protective atmosphere, the second precursor was sintered at 700° C. for 6 h to obtain a lithium manganese iron phosphate material with a carbon coating layer.

[0159] The performance of the regenerated lithium iron manganese phosphate material obtained in Example 6 and the carbon-coated lithium iron manganese phosphate material obtained in Comparative Example 1 were tested. The test method includes: thoroughly mixing the synthesized lithium iron manganese phosphate material, acetylene black and NMP (N-methyl-2-pyrrolidone) solution (concentration of 0.02 g / mL) dissolved with PVDF (polyvinylidene fluoride) in a mass ratio of 8:1:1; coating the mixed slurry on aluminum foil and drying it at 80°C for 10 hours, and then cutting the aluminum foil coated with the slurry into circular electrode sheets with a diameter of 14 mm, and after being pressed into a mold (pressure of 6 MPa), placing it in a vacuum oven at 120°C and drying it for 12 hours, and assembling a 2025 type button battery with a metal lithium sheet as the negative electrode, a diaphragm, an electrolyte, and nickel foam as filler, and performing charge and discharge tests at different rates according to the voltage range of 2.5-4.2V. The results are as follows Figure 1 As shown:

[0160] from Figure 1 It can be seen that Example 6 has a more excellent rate discharge performance than Comparative Example 1.

[0161] The embodiments of the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. At the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for regenerating lithium iron manganese phosphate material, characterized in that: include: Providing lithium iron manganese phosphate powder to be recycled; wherein the lithium iron manganese phosphate powder to be recycled includes a molecular formula of Li a Fe b Mn c PO4 material, 0<a<1, 0<b+c<1; Dispersing the lithium manganese iron phosphate powder to be recovered, tannic acid and thiourea in a solvent to obtain a first mixed solution; adding a lithium source and a manganese source to the first mixed solution to obtain a second mixed solution; The second mixed solution is reacted at 140° C.-160° C. to obtain a regenerated lithium manganese iron phosphate material.

2. The method for regenerating lithium iron manganese phosphate material according to claim 1, characterized in that: The mass ratio of the lithium manganese iron phosphate powder to be recovered to the tannic acid and the thiourea is (4-7): (2-4): (1-3).

3. The method for regenerating lithium iron manganese phosphate material according to claim 1, characterized in that: After dispersing the lithium manganese iron phosphate powder to be recovered, tannic acid and thiourea in a solvent, the method further comprises: Analyzing the molar contents of lithium, iron and manganese in the first mixed solution to obtain content analysis results; The step of adding a lithium source and a manganese source to the first mixed solution to obtain a second mixed solution comprises: According to the content analysis result, the lithium source and the manganese source are added to the first mixed solution to obtain a second mixed solution, so that the molar contents of lithium, iron and manganese in the second mixed solution satisfy: C1=C2+C3; Wherein, C1 represents the molar content of lithium element in the second mixed solution, C2 represents the molar content of iron element in the second mixed solution, and C3 represents the molar content of manganese element in the second mixed solution.

4. The method for regenerating lithium iron manganese phosphate material according to claim 1, characterized in that: The solid content of the first mixed liquid is 1%-10%.

5. The method for regenerating lithium iron manganese phosphate material according to claim 1, characterized in that: The lithium source includes lithium acetate; And / or, the manganese source comprises manganese acetate.

6. The method for regenerating lithium iron manganese phosphate material according to claim 1, characterized in that: The second mixed solution is reacted at 140° C. to 160° C. and treated, including: reacting the second mixed solution at 140° C.-160° C. to obtain a first precursor; Mixing the carbon source and the first precursor and then subjecting the mixture to ball milling to obtain a second precursor; The second precursor is sintered under a protective atmosphere to obtain the regenerated lithium manganese iron phosphate material.

7. The method for regenerating lithium iron manganese phosphate material according to claim 6, characterized in that: The step of reacting the second mixed solution at 140° C. to 160° C. comprises: The second mixed solution was reacted at 140° C.-160° C. for 5 h-7 h.

8. The method for regenerating lithium iron manganese phosphate material according to claim 6, characterized in that: The carbon source includes glucose; And / or, the mass ratio of the carbon source to the first precursor is 1:(5-10).

9. The method for regenerating lithium iron manganese phosphate material according to claim 6, characterized in that: The step of mixing the carbon source and the first precursor and then subjecting them to ball milling comprises: mixing the carbon source and the first precursor to obtain a mixture; The mixture is ball-milled at a rotation speed of 500 rpm for 4 h to 6 h, and dried to obtain the second precursor.

10. The method for regenerating lithium iron manganese phosphate material according to claim 6, characterized in that: The step of sintering the second precursor comprises: The second precursor is sintered at 600° C.-850° C. for 4 h-5 h.

11. A lithium manganese iron phosphate material, characterized in that: The material is obtained by the method for regenerating lithium manganese iron phosphate material as described in any one of claims 1 to 10.

12. A battery, characterized in that: Comprising the lithium manganese iron phosphate material as described in claim 11.

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