Material for lithium iron phosphate battery and method for recycling lithium iron phosphate material

Abstract

This application provides a lithium iron phosphate battery material and a method for regenerating lithium iron phosphate material. The regeneration method includes: primary crushing of lithium iron phosphate positive electrode sheets from waste lithium iron phosphate batteries to obtain a first mixed material; sequentially physical sieving and air classification of the first mixed material to obtain lithium iron phosphate black powder; secondary crushing of the lithium iron phosphate black powder to obtain pretreated lithium iron phosphate black powder; uniformly mixing the pretreated lithium iron phosphate black powder from different bins to obtain a second mixed material of a predetermined weight; adding a substance containing a predetermined element to the second mixed material to obtain a third mixed material; and subjecting the third mixed material to high-temperature sintering and tertiary crushing to obtain regenerated lithium iron phosphate material. By first breaking up the agglomerated secondary particles in the lithium iron phosphate black powder into single particles; and then uniformly mixing multiple batches of pretreated lithium iron phosphate black powder, the raw material composition is homogenized, thereby effectively eliminating material performance fluctuations caused by batch differences and application field differences.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environmental protection and resource comprehensive utilization, in particular, the present application relates to a lithium iron phosphate battery material and a regeneration method of lithium iron phosphate material. BACKGROUND

[0002] With the rapid development of new energy automobile industry, the power battery market dominated by lithium batteries is showing an explosive trend. Lithium iron phosphate batteries have become the most commonly used power batteries for new energy vehicles due to their high safety and good stability. However, the service life of such batteries is usually 5-8 years, which will result in a large number of batteries being scrapped. Since there is a large amount of lithium metal and high-value lithium phosphate iron in lithium iron phosphate batteries, recycling and regenerating lithium iron phosphate materials have good environmental, social and economic values.

[0003] In addition, there are a certain percentage of defective products in the production process of lithium iron phosphate batteries, resulting in a certain amount of waste positive plate. If not recycled, it will cause a huge waste of resources.

[0004] In the existing regeneration method of lithium iron phosphate material, due to the different requirements of lithium iron phosphate batteries applied in different fields in terms of rate, cycle and capacity, the indicators and morphology of lithium iron phosphate in lithium iron phosphate batteries used in different fields are different. Moreover, the performance of lithium iron phosphate batteries manufactured by different batches of the same battery factory or the same batch of different battery factories fluctuates. The above reasons ultimately result in that the performance of regenerated lithium iron phosphate material is closely related to the source of waste positive plate and scrapped lithium iron phosphate batteries, so that the waste positive plate and scrapped lithium iron phosphate batteries after regeneration are difficult to meet the requirements of the original product category. SUMMARY

[0005] In view of the shortcomings of the prior art, the present application provides a lithium iron phosphate battery material and a regeneration method of lithium iron phosphate material to solve the technical problem that the performance of regenerated lithium iron phosphate material is closely related to the source of waste positive plate and scrapped lithium iron phosphate batteries, so that the waste positive plate and scrapped lithium iron phosphate batteries after regeneration are difficult to meet the requirements of the original product category.

[0006] In a first aspect, the embodiments of the present application provide a regeneration method of lithium iron phosphate material, comprising:

[0007] The lithium iron phosphate positive plate of the waste lithium iron phosphate battery is subjected to primary crushing to obtain a first mixed material; The first mixed material is subjected to physical screening and air separation in sequence to obtain lithium iron phosphate black powder; The lithium iron phosphate black powder is subjected to secondary crushing to obtain pretreated lithium iron phosphate black powder; Pretreated lithium iron phosphate black powder from different silos is mixed evenly to obtain a second mixed material of a preset weight. Add a substance containing a preset element to the second mixture to obtain a third mixture; The third mixture is subjected to high-temperature sintering and three-stage pulverization to obtain recycled lithium iron phosphate material.

[0008] Optionally, before the lithium iron phosphate cathode sheets from waste lithium iron phosphate batteries are subjected to primary crushing to obtain the first mixed material, the process further includes: The charged, used lithium iron phosphate batteries are crushed to obtain fragments; The fragments are oxidized and calcined to oxidize some of the ferrous iron in the positive electrode sheet of the fragments to generate ferric iron, resulting in a fourth mixed material; the positive electrode sheet in the fourth mixed material is yellow; The positive electrode sheet was separated by color sorting; Furthermore, after uniformly mixing pretreated lithium iron phosphate black powder from different silos to obtain a second mixed material of a predetermined weight, and before adding a substance containing a predetermined element to the second mixed material to obtain a third mixed material, the process further includes: The second mixture is subjected to a reducing treatment.

[0009] Optionally, the second mixture is subjected to a reducing treatment, including: The second mixture is placed in a mixer. Under an inert atmosphere, a reducing agent solution is added to the mixer and stirred until the content of ferric iron in the mixer is equal to or less than the target content as determined by titration. Alternatively, sugars can be added to the second mixture, and high-temperature sintering can be carried out under an inert atmosphere.

[0010] Optionally, the size of the fragment is greater than or equal to 5 mm and less than or equal to 2 cm.

[0011] Optionally, after the first mixture is subjected to physical sieving and air classification to obtain lithium iron phosphate black powder; and before the lithium iron phosphate black powder is subjected to secondary pulverization to obtain pretreated lithium iron phosphate black powder, the process further includes: The lithium iron phosphate black powder is oxidized and calcined to remove carbon; Furthermore, after uniformly mixing pretreated lithium iron phosphate black powder from different silos to obtain a second mixed material of a predetermined weight; and before adding a substance containing a predetermined element to the second mixed material to obtain a third mixed material, the process further includes: The second mixture is subjected to a reducing treatment.

[0012] Optionally, the lithium iron phosphate black powder is oxidized and calcined to remove carbon, including: Calcium oxide particles with a particle size greater than 0.5 mm are added to the lithium iron phosphate black powder to obtain a fifth mixture; the amount of calcium oxide particles added includes 5% of the mass of the second mixture. The fifth mixture is added to the preheated calcining apparatus and kept at that temperature for 5-12 hours in an air or pure oxygen atmosphere; the preheating temperature of the calcining apparatus includes 400°C.

[0013] Optionally, the calcination apparatus includes a replaceable inner liner.

[0014] Optionally, the median diameter of the pretreated lithium iron phosphate black powder is not less than 0.3 micrometers and not more than 5 micrometers.

[0015] Secondly, embodiments of this application provide a material for a lithium iron phosphate battery, which is manufactured based on any of the regeneration methods described in the first aspect above.

[0016] Optionally, the lithium iron phosphate battery further includes at least one of the following materials: The median diameter of the material in the lithium iron phosphate battery is greater than or equal to 0.8 micrometers and less than or equal to 2.5 micrometers; The compaction density of the lithium iron phosphate battery material is greater than or equal to 2.5 grams per cubic centimeter; At a charge / discharge rate of 0.1C, each gram of lithium iron phosphate material can release a capacity greater than or equal to 155 mAh.

[0017] The beneficial technical effects of the technical solutions provided in this application include: In the lithium iron phosphate material recycling method provided in this application embodiment, the lithium iron phosphate positive electrode sheet of the waste lithium iron phosphate battery is sequentially subjected to a first crushing, physical sieving and air classification process to obtain lithium iron phosphate black powder; then, the lithium iron phosphate black powder is subjected to a second crushing to obtain pretreated lithium iron phosphate black powder. Pretreated lithium iron phosphate black powder from different silos is mixed evenly to obtain a second mixture of a predetermined weight. Then, a substance containing a predetermined element is added to the second mixture to obtain a third mixture. This third mixture is then subjected to high-temperature sintering and three-stage pulverization to obtain recycled lithium iron phosphate material. Secondary pulverization breaks up agglomerated secondary particles in the lithium iron phosphate black powder, ensuring that the pretreated lithium iron phosphate black powder mainly consists of uniformly sized single particles. Finally, pretreated lithium iron phosphate black powder from different batches and applied in different fields is mixed evenly to homogenize the raw material composition, effectively eliminating material performance fluctuations caused by batch and application differences, and improving the consistency and stability of the recycled lithium iron phosphate material.

[0018] Additional aspects and advantages of this application will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of this application. Attached Figure Description

[0019] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 A schematic flowchart illustrating a method for regenerating lithium iron phosphate material provided in this application embodiment; Figure 2 A schematic flowchart illustrating a specific regeneration method for lithium iron phosphate material provided in this application embodiment; Figure 3 This is a schematic flowchart illustrating another specific regeneration method for lithium iron phosphate material provided in an embodiment of this application. Detailed Implementation

[0020] The embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the embodiments described below with reference to the accompanying drawings are exemplary descriptions for explaining the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions of the embodiments of this application.

[0021] Those skilled in the art will understand that, unless specifically stated otherwise, the terms "described" and "the" as used herein may also include plural forms. It should be further understood that the term "comprising" as used in the specification of this application means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude other features, information, data, steps, operations, elements, components, and / or combinations thereof supported by the art. The term "and / or" as used herein refers to at least one of the items defined by the term; for example, "A and / or B" can be implemented as "A," or as "B," or as "A and B."

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0023] With the rapid development of the new energy vehicle industry, the market for power batteries, primarily lithium batteries, has experienced explosive growth. Lithium iron phosphate (LFP) batteries, due to their high safety and stability, have become the most commonly used power batteries in new energy vehicles. However, these batteries typically have a lifespan of 5-8 years, leading to a large number of batteries facing obsolescence. Because LFP batteries contain a large amount of scarce lithium metal and valuable iron phosphate, resource recycling and regeneration of LFP materials has significant environmental, social, and economic value.

[0024] In addition, a certain percentage of defective products exist during the production of lithium iron phosphate batteries, resulting in a certain amount of waste positive electrode sheets. If these are not recycled, it will lead to a huge waste of resources.

[0025] In existing methods for regenerating lithium iron phosphate materials, the different rate, cycle, and capacity requirements of lithium iron phosphate batteries used in different fields lead to variations in the various indicators and morphology of lithium iron phosphate in these batteries. Furthermore, the performance of lithium iron phosphate batteries manufactured in different batches from the same battery manufacturer or even the same batch from different battery manufacturers fluctuates. All these factors ultimately result in the performance of regenerated lithium iron phosphate materials being closely related to the source of waste cathode sheets and scrapped lithium iron phosphate batteries, making it difficult for scrapped lithium iron phosphate batteries and waste cathode sheets to meet the requirements of the original product types after regeneration.

[0026] The technical solution of this application and how it solves the above-mentioned technical problems are described in detail below with specific embodiments. It should be noted that the following embodiments can be referenced, borrowed, or combined with each other, and the same terms, similar features, and similar implementation steps in different embodiments will not be described again.

[0027] This application provides a method for regenerating lithium iron phosphate materials, such as... Figure 1 As shown, the regeneration method includes the following steps: S101: The lithium iron phosphate positive electrode sheet of the waste lithium iron phosphate battery is crushed in the first stage to obtain the first mixed material.

[0028] S102: The first mixture is subjected to physical sieving and air classification in sequence to obtain lithium iron phosphate black powder.

[0029] S103: The lithium iron phosphate black powder is subjected to secondary pulverization to obtain pretreated lithium iron phosphate black powder.

[0030] S104: Mix the pretreated lithium iron phosphate black powder from different silos evenly to obtain a second mixed material of a preset weight.

[0031] S105: Add a substance containing a preset element to the second mixture to obtain a third mixture.

[0032] S106: The third mixture is subjected to high-temperature sintering and three-stage pulverization to obtain recycled lithium iron phosphate material.

[0033] In the lithium iron phosphate material recycling method provided in this application embodiment, the lithium iron phosphate positive electrode sheet of the waste lithium iron phosphate battery is sequentially subjected to a first crushing, physical sieving and air classification process to obtain lithium iron phosphate black powder; then, the lithium iron phosphate black powder is subjected to a second crushing to obtain pretreated lithium iron phosphate black powder. Pretreated lithium iron phosphate black powder from different silos is mixed evenly to obtain a second mixture of a predetermined weight. Then, a substance containing a predetermined element is added to the second mixture to obtain a third mixture. This third mixture is then subjected to high-temperature sintering and three-stage pulverization to obtain recycled lithium iron phosphate material. Secondary pulverization breaks up agglomerated secondary particles in the lithium iron phosphate black powder, ensuring that the pretreated lithium iron phosphate black powder mainly consists of uniformly sized single particles. Finally, pretreated lithium iron phosphate black powder from different batches and applied in different fields is mixed evenly to homogenize the raw material composition, effectively eliminating material performance fluctuations caused by batch and application differences, and improving the consistency and stability of the recycled lithium iron phosphate material.

[0034] It should be noted that the lithium iron phosphate cathode sheet of the waste lithium iron phosphate battery in this application includes cathode sheets recycled after the waste lithium iron phosphate battery is dismantled, as well as cathode sheets from other sources such as waste cathode sheets generated during the battery production process.

[0035] In this embodiment, the primary crushing can be performed using an impact mill or roller mill to initially crush waste positive electrode sheets from battery factories, or by crushing positive electrode sheets separated from scrapped lithium iron phosphate batteries through a series of color sorting operations. Physical sieving involves using a sieve to classify the particle size of the first mixture, separating larger-sized metal impurities and insufficiently crushed current collector fragments. Subsequently, cyclone separation is performed 1-3 times for air classification, using airflow to further separate light non-metallic materials from heavy metallic impurities, thereby obtaining pure lithium iron phosphate black powder.

[0036] In this embodiment, the secondary crushing employs a high-speed air jet mill, sand mill, or mechanical impact mill to fully dissociate the agglomerated secondary particles in the lithium iron phosphate black powder, resulting in a more uniform particle size distribution in the pretreated lithium iron phosphate black powder. The preset weight of the second mixed material is over 10 tons.

[0037] Optionally, in one embodiment of this application, a specific method for regenerating lithium iron phosphate material is provided, the process flow diagram of which is shown below. Figure 2 As shown, it includes the following steps: S201: Crush charged used lithium iron phosphate batteries to obtain fragments.

[0038] S202: The fragments are oxidized and calcined, so that some of the divalent iron in the positive electrode of the fragments is oxidized to trivalent iron, resulting in the fourth mixture; the positive electrode in the fourth mixture is yellow.

[0039] S203: Lithium iron phosphate cathode sheets are separated by color sorting.

[0040] S204: The lithium iron phosphate positive electrode sheet of the waste lithium iron phosphate battery is crushed in the first stage to obtain the first mixed material.

[0041] Optionally, the lithium iron phosphate positive electrode of the waste lithium iron phosphate battery is a lithium iron phosphate positive electrode separated by color sorting.

[0042] S205: The first mixture is subjected to physical sieving and air classification in sequence to obtain lithium iron phosphate black powder.

[0043] S206: Lithium iron phosphate black powder is subjected to secondary pulverization to obtain pretreated lithium iron phosphate black powder.

[0044] S207: Mix the pretreated lithium iron phosphate black powder from different silos evenly to obtain a second mixed material of a preset weight.

[0045] S208: The second mixture is subjected to a reducing treatment.

[0046] Optionally, the second mixture is subjected to a reducing treatment to obtain a reduced second mixture.

[0047] S209: Add a substance containing a preset element to the second mixture to obtain a third mixture.

[0048] Optionally, a substance containing a preset element is added to the reduced second mixture to obtain a third mixture.

[0049] S210: The third mixture is subjected to high-temperature sintering and three-stage pulverization to obtain recycled lithium iron phosphate material.

[0050] In this embodiment, under an inert atmosphere such as nitrogen, discarded lithium iron phosphate batteries are shredded while charged, yielding a mixture of positive electrode fragments bonded with positive electrode material powder, negative electrode fragments bonded with negative electrode material powder, and separator and electrolyte residues. This mixture contains graphite and copper. Subsequently, the mixture is oxidized and calcined at high temperature, removing separator and electrolyte residues, oxidizing and decomposing the PVDF (polyvinylidene fluoride) binder, and oxidizing some of the ferrous iron in the positive electrode fragments bonded with positive electrode material powder to ferric iron, resulting in a fourth mixture. The positive electrode fragments in this fourth mixture are yellow. Next, a color sorter separates the yellow positive electrode fragments from other materials, quickly separating the positive and negative electrode fragments by color. This eliminates the need for complex physical sorting of impurities such as graphite and copper in the mixture, improving the recovery efficiency and purity of the positive electrode material.

[0051] The specific operation of separating the positive electrode sheet by color sorting in this embodiment includes: feeding the fourth mixed material into the color sorter, feeding the fourth mixed material into the sorting channel by vibration, using a high-resolution optical sensor to identify other fragments besides the yellow positive electrode sheet fragments, and blowing the identified other fragments away from the main material flow through an airflow nozzle or ejector device, so that the yellow positive electrode sheet fragments finally fall into the finished product bin, achieving efficient separation.

[0052] In this embodiment, the specific method for high-temperature oxidation calcination of a mixture of positive electrode fragments bonded with positive electrode material powder, negative electrode fragments bonded with negative electrode material powder, separator, and electrolyte residue includes: placing the mixture in a calcination device such as a fluidized bed, vertical reactor, or rotary kiln preheated to 480-530℃ under air or pure oxygen atmosphere for oxidation treatment, and holding at that temperature for 5-12 hours. The oxidation process can be performed once or twice. Calcium oxide particles can also be added during the high-temperature oxidation calcination operation; specifically, calcium oxide particles with a particle size greater than 0.5 mm are first added to the mixture, with the amount of calcium oxide particles including 5% of the mixture's mass; then the mixture and calcium oxide particles are placed together in the calcination device for calcination; during the calcination process, calcium oxide, as an adsorbent, can absorb and eliminate fluorides such as hydrogen fluoride produced by the decomposition of the binder PVDF, effectively inhibiting the release of harmful gases, improving the environmental friendliness of the treatment process, and preventing corrosion of equipment by fluorides. In addition, calcium oxide can promote the complete combustion of organic matter, improve calcination efficiency, and reduce residual carbon, thereby enhancing the purity and quality of subsequent material recycling. It should be noted that in high-temperature oxidation calcination operations, the preheating temperature of the calcination apparatus ranges from 480-530℃ if calcium oxide particles are not added, and from 400℃ if calcium oxide particles are added.

[0053] In this embodiment, the calcining device uses a replaceable inner liner, so that when the calcining device is corroded, only the inner liner needs to be replaced to continue using it, without the need to replace the entire device, thus reducing maintenance costs and downtime.

[0054] In this embodiment of the application, the pretreated lithium iron phosphate black powder from different silos is mixed evenly to obtain a second mixed material of a preset weight. Then, the second mixed material is subjected to a reducing treatment to obtain a reduced second mixed material, so that the trivalent iron in the second mixed material is reduced to divalent iron, thereby restoring the electrochemical activity of lithium iron phosphate.

[0055] Optionally, in one embodiment of this application, such as Figure 2 As shown, step S208 above, which involves a reducing treatment of the second mixture, includes: The second mixture is placed in a mixer. Under an inert atmosphere, a reducing agent solution is added to the mixer and stirred until the content of ferric iron in the mixer is equal to or less than the target content, as determined by titration.

[0056] Alternatively, sugars can be added to the second mixture, and high-temperature sintering can be carried out under an inert atmosphere.

[0057] In this embodiment, the second mixture is placed in a mixer such as a ribbon mixer. Under an inert atmosphere such as nitrogen, a reducing agent solution is added and the mixture is continuously stirred until the content of ferric iron in the mixer is less than or equal to 20% of the total iron mass in the second mixture, as determined by titration. This completes the reduction treatment. After the reaction is complete, water is removed by pressure filtration to obtain a second mixture containing ferrous iron. The reducing agent solution includes aqueous solutions of ascorbic acid or sodium bisulfite, and the reaction temperature ranges from 0 to 200°C.

[0058] In this embodiment, a solid-state method can also be used to reduce the second mixture, that is, the second mixture is mixed with sugars such as glucose and sucrose and sintered under an inert atmosphere to fully reduce ferric iron to ferrous iron. The sintering temperature includes 400-800℃, the holding time includes 10-30 hours, and the amount of sugars such as glucose and sucrose added includes 0.2%-5% of the mass of the second mixture. The addition of sugars such as glucose and sucrose can improve the integrity of the carbon coating layer, and the amount of sugar added needs to be determined based on the residual carbon in the lithium iron phosphate cathode sheet of the waste lithium iron phosphate battery and the yield of the added sugars.

[0059] After reducing the second mixture to obtain a reduced second mixture, a substance containing a predetermined element is added to the reduced second mixture to obtain a third mixture. The third mixture is then subjected to high-temperature sintering and three-stage pulverization to obtain regenerated lithium iron phosphate material. The predetermined element includes one or more of lithium, iron, titanium, manganese, carbon, sulfur, nitrogen, and phosphorus. Lithium can be supplemented by adding lithium carbonate, titanium by adding titanium dioxide, and vanadium by adding vanadium pentoxide or ammonium vanadate. Sugars are added for carbon layer coating to improve the electrochemical performance of the material. When adding the substance containing the predetermined element to the reduced second mixture, a mixing device such as a ribbon mixer can be used to thoroughly mix the reduced second mixture with the substance containing the predetermined element to form a uniform third mixture, ensuring effective doping and coating of each element during subsequent sintering. Under a nitrogen atmosphere, the third mixture is placed in a roller kiln for high-temperature sintering at 600-850℃ for 20-24 hours. This allows the added compound containing preset elements to fully react with the lithium iron phosphate in the third mixture and complete crystal phase reconstruction, forming a regenerated lithium iron phosphate material with a complete crystal lattice structure. The sintered product is then subjected to three stages of grinding and demagnetization sieving to obtain a regenerated lithium iron phosphate material with a uniform particle size distribution. The three stages of grinding include air jet milling.

[0060] It should be noted that, in the embodiments of this application, adding metal elements such as lithium, titanium, and manganese to the reduced second mixture aims to regulate the crystal structure of the recycled material, and adding non-metallic elements such as carbon, sulfur, and nitrogen to the reduced second mixture aims to perform carbon coating and heteroatom doping to improve the conductivity of the carbon layer.

[0061] Optionally, in one embodiment of this application, such as Figure 2 As shown, the size of the fragment is greater than or equal to 5 mm and less than or equal to 2 cm.

[0062] In the embodiments of this application, under the protection of an inert atmosphere such as nitrogen, the scrapped lithium iron phosphate battery is shredded under charge by a shredder to obtain positive electrode fragments with positive electrode material powder and negative electrode fragments with negative electrode material powder. The size of the positive electrode fragments is greater than or equal to 5 mm and less than or equal to 2 cm, so that the positive electrode fragments and negative electrode fragments can be separated by a color sorter in a high manner.

[0063] Optionally, in one embodiment of this application, another specific method for regenerating lithium iron phosphate material is provided, the process flow diagram of which is shown below. Figure 3 As shown, it includes the following steps: S301: The lithium iron phosphate positive electrode sheet of the waste lithium iron phosphate battery is crushed in the first stage to obtain the first mixed material.

[0064] S302: The first mixed material is subjected to physical sieving and air classification in sequence to obtain lithium iron phosphate black powder.

[0065] S303: Lithium iron phosphate black powder is oxidized and calcined to remove carbon.

[0066] Optionally, the lithium iron phosphate black powder is oxidized and calcined to obtain oxidized and calcined lithium iron phosphate black powder.

[0067] S304: Lithium iron phosphate black powder is subjected to secondary pulverization to obtain pretreated lithium iron phosphate black powder.

[0068] Optionally, the oxidized and calcined lithium iron phosphate black powder is subjected to secondary pulverization to obtain pretreated lithium iron phosphate black powder.

[0069] S305: Mix the pretreated lithium iron phosphate black powder from different silos evenly to obtain a second mixed material of a preset weight.

[0070] S306: The second mixture is subjected to a reducing treatment.

[0071] Optionally, the second mixture is subjected to a reducing treatment to obtain a reduced second mixture.

[0072] S307: Add a substance containing a preset element to the second mixture to obtain a third mixture.

[0073] Optionally, a substance containing a preset element is added to the reduced second mixture to obtain a third mixture.

[0074] S308: The third mixture is subjected to high-temperature sintering and three-stage pulverization to obtain recycled lithium iron phosphate material.

[0075] In this embodiment, lithium iron phosphate (LFP) black powder is oxidized and calcined to remove carbon. During the oxidation and calcination process, the ferrous iron in the LFP black powder is oxidized to ferric iron, resulting in oxidized and calcined LFP black powder. Subsequently, the oxidized and calcined LFP black powder is subjected to secondary pulverization to obtain pretreated LFP black powder. The pretreated LFP black powder from different silos is then mixed evenly to obtain a second mixture of a predetermined weight. Next, the second mixture is subjected to a reduction treatment to reduce the ferric iron in the second mixture to ferrous iron, resulting in a reduced second mixture. This improves the integrity of the carbon coating layer, electrical performance, and specific capacity of the final LFP material.

[0076] It should be noted that the process flow and parameters for reducing the second mixture to obtain the reduced second mixture are the same in the specific regeneration methods of the two lithium iron phosphate materials.

[0077] After reducing the second mixture to obtain a reduced second mixture, a substance containing a predetermined element is added to the reduced second mixture to obtain a third mixture. The third mixture is then subjected to high-temperature sintering and three-stage pulverization to obtain regenerated lithium iron phosphate material. The predetermined element includes one or more of lithium, iron, titanium, manganese, carbon, sulfur, nitrogen, and phosphorus. Lithium can be supplemented by adding lithium carbonate, titanium by adding titanium dioxide, and vanadium by adding vanadium pentoxide or ammonium vanadate. Sugars are added for carbon layer coating to improve the electrochemical performance of the material. When adding the substance containing the predetermined element to the reduced second mixture, a mixing device such as a ribbon mixer can be used to thoroughly mix the reduced second mixture with the substance containing the predetermined element to form a homogeneous third mixture, ensuring effective doping and coating of each element during subsequent sintering. Under a nitrogen atmosphere, the third mixture is placed in a roller kiln for high-temperature sintering at 600-850℃ for 20-24 hours. This allows the added compound containing preset elements to fully react with the lithium iron phosphate in the third mixture and complete crystal phase reconstruction, forming a regenerated lithium iron phosphate material with a complete crystal lattice structure. The sintered product is then subjected to three stages of grinding and demagnetization sieving to obtain a regenerated lithium iron phosphate material with a uniform particle size distribution. The three stages of grinding include air jet milling.

[0078] It should be noted that, in the embodiments of this application, the addition of metallic elements such as lithium, titanium, and manganese to the reduced second mixture aims to regulate the crystal structure of the recycled material. The addition of non-metallic elements such as carbon, sulfur, and nitrogen to the reduced second mixture aims to perform carbon coating and heteroatom doping, thereby improving the conductivity of the carbon layer. The addition of non-metallic elements such as carbon, sulfur, and phosphorus to the reduced second mixture is controlled to be below 500 ppm (milligrams per kilogram).

[0079] Optionally, in one embodiment of this application, such as Figure 3 As shown, lithium iron phosphate black powder is oxidized and calcined to remove carbon, including: Calcium oxide particles with a particle size greater than 0.5 mm were added to lithium iron phosphate black powder to obtain the fifth mixture; the amount of calcium oxide particles added included 5% of the mass of the second mixture.

[0080] Add the fifth mixture to the preheated calcining apparatus and hold it at that temperature for 5-12 hours in an air or pure oxygen atmosphere; the preheating temperature of the calcining apparatus includes 400℃.

[0081] Under an air or pure oxygen atmosphere, calcium oxide particles with a diameter greater than 0.5 mm are added to the second mixture and mixed evenly to obtain the fifth mixture. The amount of calcium oxide particles added is 5% of the mass of the second mixture. The fifth mixture is then placed in a calcination device such as a fluidized bed, vertical reactor, or rotary kiln preheated to 400℃ for oxidation treatment, held at this temperature for 5-12 hours, to obtain oxidized and calcined lithium iron phosphate black powder. The oxidation and calcination process can be performed once or twice. During the oxidation and calcination process, calcium oxide acts as an adsorbent, absorbing and eliminating fluorides such as hydrogen fluoride produced by the decomposition of the binder PVDF, effectively inhibiting the release of harmful gases, improving the environmental friendliness of the treatment process, and preventing corrosion of equipment by fluorides. Furthermore, calcium oxide can promote the complete combustion of organic matter, improve calcination efficiency, reduce residual carbon, and thus improve the purity and quality of subsequent material recovery.

[0082] Optionally, in some embodiments, in the process of oxidizing and calcining lithium iron phosphate black powder to remove carbon, calcium oxide particles are not added. The lithium iron phosphate black powder is directly placed in the calcination device for oxidation and calcination. It should be noted that in the oxidation and calcination operation, if calcium oxide particles are not added, the preheating temperature of the calcination device includes 480-530°C, and if calcium oxide particles are added, the preheating temperature of the calcination device includes 400°C; the other process parameters are the same and will not be repeated here.

[0083] Optionally, in an optional embodiment of this application, such as Figures 1-3 As shown, the calcination apparatus includes a replaceable inner liner.

[0084] In this embodiment, the calcination device used in the oxidation calcination process adopts a replaceable inner liner, so that when the calcination device is corroded, only the inner liner needs to be replaced to continue using it, without the need to replace the entire equipment, thus reducing maintenance costs and downtime.

[0085] Optionally, in an optional embodiment of this application, such as Figures 1-3 As shown, the median diameter of the pretreated lithium iron phosphate black powder is not less than 0.3 micrometers and not more than 5 micrometers.

[0086] In the embodiments of this application, the median diameter of the pretreated lithium iron phosphate black powder is greater than or equal to 0.3 micrometers and less than or equal to 5 micrometers. This particle size range is beneficial for mixing the pretreated lithium iron phosphate black powder from different silos evenly and improving the consistency of the material.

[0087] Based on the same inventive concept, this application provides a material for a lithium iron phosphate battery, which is manufactured based on the regeneration method of any of the above embodiments.

[0088] It should be noted that since the materials of the lithium iron phosphate batteries in this application embodiment are manufactured based on the regeneration method of any of the above embodiments, the materials of the lithium iron phosphate batteries in this application embodiment also have the above-mentioned beneficial effects of the regeneration method of this application embodiment, which will not be repeated here.

[0089] Optionally, in one embodiment of this application, the lithium iron phosphate battery further includes at least one of the following materials: The median diameter of the materials used in lithium iron phosphate batteries is greater than or equal to 0.8 micrometers and less than or equal to 2.5 micrometers.

[0090] The compaction density of lithium iron phosphate battery materials is greater than or equal to 2.5 grams per cubic centimeter.

[0091] At a charge / discharge rate of 0.1C, each gram of lithium iron phosphate material can release a capacity greater than or equal to 155 mAh.

[0092] In the embodiments of this application, the lithium iron phosphate battery material manufactured by the regeneration method of any of the above embodiments exhibits excellent electrochemical performance and cycle stability. At a charge / discharge rate of 0.1C (coulomb), each gram of lithium iron phosphate material can release a capacity greater than or equal to 155 mAh. The material has a dense and uniform structure with concentrated particle distribution, effectively improving the electrode coating performance and battery energy density. Simultaneously, due to its low impurity content and low residual carbon, it significantly reduces the battery's internal resistance and thermal runaway risk, meeting the manufacturing requirements for high-safety power batteries.

[0093] The recycling method of this application and the materials of the lithium iron phosphate battery manufactured therefrom will be further described below with reference to specific embodiments and comparative examples.

[0094] Example 1 Under an inert atmosphere such as nitrogen, discarded lithium iron phosphate batteries are shredded while charged, yielding a mixture of positive electrode fragments (coated with positive electrode material powder), negative electrode fragments (coated with negative electrode material powder), and separator and electrolyte residues. This mixture is then placed in a rotary kiln preheated to 500°C for oxidation calcination in air, held for 8 hours, with compressed air parameters of 0.5 MPa and 80 Nm³ / h. 3 / h (standard cubic meters per hour); after cooling, the fourth mixture after oxidation and degumming is obtained; using yellow as the mark color, the positive electrode fragments in the fourth mixture are separated from other materials by a color sorter equipped with a high-precision CCD (visual inspection system); the positive electrode fragments separated by color sorting are crushed in the first stage by a mechanical impact mill, with the main speed of the mechanical impact mill at 1200 RPM (revolutions per minute) and the internal classification speed at 800 RPM, to obtain the first mixture.

[0095] After the first mixture is passed through a 200-mesh sieve, the undersize material undergoes two external classification separations at a speed of 2800 RPM, yielding lithium iron phosphate black powder. This lithium iron phosphate black powder is then subjected to an air jet mill, where it is pulverized using compressed air at a pressure of 0.7 MPa to obtain pretreated lithium iron phosphate black powder with a D50 (median diameter) of 1.5 micrometers. 200 tons of the pretreated lithium iron phosphate black powder are then placed in eight 50m... 3 In a (cubic meter) silo, 8 silos simultaneously discharge material into a 25m³ capacity silo. 3 In the ribbon mixer, the load is increased to 10 tons and stirred at 20 RPM for 30 minutes to obtain the second mixed material of the preset weight.

[0096] Add ascorbic acid (20% by mass) to the second mixture at 10% of its mass. Stir for 30 minutes. If the ferric iron content is less than 20% of the total iron mass in the second mixture, the reaction is considered complete, yielding the reduced second mixture. Add a substance containing a predetermined element to the reduced second mixture, specifically: add titanium dioxide at 0.1% of its mass and... Add glucose at 0.5% of the mass of the reduced second mixture, add ethanethiol, and supplement lithium carbonate to a total Li content of 4.2% based on the lithium content of the scrapped lithium iron phosphate batteries. Stir the mixture in a ribbon mixer at 20 RPM for 30 minutes to obtain the third mixture. Under nitrogen atmosphere protection, place the third mixture in a roller kiln for high-temperature sintering at 720℃±3℃ for 24 hours. The sintered product is then subjected to three-stage pulverization by air jet milling, followed by demagnetization screening to obtain regenerated lithium iron phosphate material.

[0097] Example 2 Under an inert atmosphere such as nitrogen, discarded lithium iron phosphate batteries are shredded while charged, yielding a mixture of positive electrode fragments bonded with positive electrode material powder, negative electrode fragments bonded with negative electrode material powder, and separator and electrolyte residue. This mixture is then placed in a rotary kiln preheated to 530°C for oxidation calcination in air, held at that temperature for 6 hours, with compressed air parameters of 0.5 MPa and 80 Nm³ / h. 3 / h; After cooling, the fourth mixture after oxidation and degumming is obtained; Using yellow as the mark color, the positive electrode fragments in the fourth mixture are separated from other materials by a color sorter with a high-precision CCD; The positive electrode separated by color sorting is crushed in the first stage by a mechanical impact mill with a main speed of 1200 RPM and an internal classification speed of 800 RPM to obtain the first mixture.

[0098] After the first mixture is passed through a 200-mesh sieve, the undersize material undergoes two external classification separations at a speed of 2800 RPM, yielding lithium iron phosphate black powder. This lithium iron phosphate black powder is then subjected to an air jet mill, where it is pulverized using compressed air at a pressure of 0.6 MPa to obtain pretreated lithium iron phosphate black powder with a D50 of 2 micrometers. 200 tons of the pretreated lithium iron phosphate black powder are then placed in eight 50m... 3 In the silo, 8 silos simultaneously discharge material into a 25m³ capacity silo. 3 In the ribbon mixer, the load is increased to 10 tons and stirred at 20 RPM for 30 minutes to obtain the second mixed material of the preset weight.

[0099] Add ascorbic acid (20% by mass) to the second mixture at 10% of its mass. Stir for 30 minutes. If the ferric iron content is less than 20% of the total iron mass in the second mixture, the reaction is considered complete, yielding the reduced second mixture. Add a substance containing a predetermined element to the reduced second mixture, specifically: add titanium dioxide at 0.5% of its mass and... Vanadium pentoxide was added, and glucose was added at 3% of the reduced second mixture. Lithium carbonate was added to bring the total Li content to 4.2% based on the lithium content of the scrapped lithium iron phosphate batteries. The mixture was stirred in a ribbon mixer at 20 RPM for 30 minutes to obtain the third mixture. Under nitrogen atmosphere protection, the third mixture was placed in a roller kiln for high-temperature sintering at 730℃±3℃ for 20 hours. The sintered product was then subjected to three-stage pulverization by air jet milling, followed by demagnetization and sieving to obtain the regenerated lithium iron phosphate material.

[0100] Example 3 Scrap lithium iron phosphate battery cathode sheets or waste cathode sheets from battery factories are subjected to primary crushing using a mechanical impact mill. The main mill speed is 1000 RPM, and the internal classifier speed is 750 RPM, yielding a first mixed material. After passing through a 200-mesh sieve, the undersize material undergoes two external classification separations at a speed of 3000 RPM, resulting in lithium iron phosphate black powder.

[0101] Under air atmosphere, lithium iron phosphate black powder was placed in a rotary kiln preheated to 480℃ for oxidation and calcination, and held at that temperature for 12 hours. The compressed air parameters were 0.5MPa and 80Nm. 3 / h; After cooling, oxidized and calcined lithium iron phosphate black powder is obtained; The oxidized and calcined lithium iron phosphate black powder is then subjected to air jet milling with compressed air at a pressure of 0.7 MPa to obtain pretreated lithium iron phosphate black powder with a D50 of 1.4 micrometers; 200 tons of pretreated lithium iron phosphate black powder are placed in eight 50m... 3 In the silo, 8 silos simultaneously discharge material into a 25m³ capacity silo. 3 In the ribbon mixer, the load is increased to 10 tons and stirred at 20 RPM for 30 minutes to obtain the second mixed material of the preset weight.

[0102] Add ascorbic acid (20% by mass) to the second mixture at 10% of its mass. Stir for 30 minutes. If the ferric iron content is less than 20% of the total iron mass in the second mixture, the reaction is considered complete, yielding the reduced second mixture. Add a substance containing a predetermined element to the reduced second mixture: add titanium dioxide at 0.15% of its mass and pentoxide at 0.05% of its mass. Vanadium dioxide was added at 2% of the mass of the reduced second mixture, and lithium carbonate was added to bring the total Li content to 4.2% based on the lithium content of the scrapped lithium iron phosphate battery cathode sheets or waste cathode sheets from battery factories. The mixture was stirred in a ribbon mixer at 20 RPM for 30 minutes to obtain the third mixture. Under nitrogen atmosphere protection, the third mixture was placed in a roller kiln for high-temperature sintering at 735℃±3℃ for 20 hours. The sintered product was then subjected to three-stage pulverization by air jet milling, followed by demagnetization and sieving to obtain the regenerated lithium iron phosphate material.

[0103] Example 4 Scrap lithium iron phosphate battery cathode sheets or waste cathode sheets from battery factories are subjected to primary crushing using a mechanical impact mill. The main mill speed is 1200 RPM, and the internal classifier speed is 700 RPM, yielding a first mixed material. After passing through a 200-mesh sieve, the undersize material undergoes two external classification separations at a speed of 2800 RPM, resulting in lithium iron phosphate black powder.

[0104] Under air atmosphere, lithium iron phosphate black powder was placed in a rotary kiln preheated to 515℃ for oxidation and calcination, and held at that temperature for 5 hours. The compressed air parameters were 0.5MPa and 80Nm. 3 / h; After cooling, oxidized and calcined lithium iron phosphate black powder is obtained; The oxidized and calcined lithium iron phosphate black powder is then subjected to air jet milling with compressed air at a pressure of 0.7 MPa to obtain pretreated lithium iron phosphate black powder with a D50 of 1.6 micrometers; 200 tons of pretreated lithium iron phosphate black powder are placed in eight 50m...3 In the silo, 8 silos simultaneously discharge material into a 25m³ capacity silo. 3 In the ribbon mixer, the load is increased to 10 tons and stirred at 20 RPM for 30 minutes to obtain the second mixed material of the preset weight.

[0105] Add sodium bisulfite (10% by mass) to the second mixture, based on 80% of the mass of ferric iron determined by titration. Stir for 30 minutes. If the ferric iron content is less than 20% of the total iron mass in the second mixture, the reaction is considered complete, yielding the reduced second mixture. Add a substance containing a predetermined element to the reduced second mixture, specifically: add titanium dioxide at 0.5% of the mass of the reduced second mixture, and add... Vanadium pentoxide is added, and glucose is added at 1.5% of the mass of the reduced second mixture. Lithium carbonate is added to bring the total Li content to 4.2% based on the lithium content of the scrapped lithium iron phosphate battery cathode sheets or waste cathode sheets from battery factories. The mixture is stirred in a ribbon mixer at 20 RPM for 30 minutes to obtain the third mixture. Under nitrogen atmosphere protection, the third mixture is placed in a roller kiln for high-temperature sintering at 730℃±3℃ for 22 hours. The sintered product is then subjected to three-stage pulverization by air jet milling, followed by demagnetization and sieving to obtain regenerated lithium iron phosphate material.

[0106] Comparative Example 1 Under an inert atmosphere such as nitrogen, discarded lithium iron phosphate batteries are shredded while charged, yielding a mixture of positive electrode fragments bonded with positive electrode material powder, negative electrode fragments bonded with negative electrode material powder, and separator and electrolyte residues. This mixture is then placed in a rotary kiln preheated to 500°C for oxidation calcination in air, held at that temperature for 8 hours, with compressed air parameters of 0.5 MPa and 80 Nm³ / h. 3 / h; After cooling, the oxidized and degummed mixture is obtained; then, the oxidized and degummed mixture is pulverized by a mechanical impact mill with a main machine speed of 1200 RPM and an internal classifier speed of 800 RPM to obtain the pulverized mixture.

[0107] After the pulverized mixture is passed through a 200-mesh sieve, the undersize material undergoes three external grading separations at a speed of 2800 RPM, yielding low-purity lithium iron phosphate black powder. The lithium iron phosphate black powder is then placed in a ribbon mixer, with glucose added at 3% of the powder's mass, and lithium carbonate added to bring the total Li content to 4.2% based on the lithium content of the discarded lithium iron phosphate batteries. The ribbon mixer is then stirred at 20 RPM for 30 minutes to obtain a mixture. Next, under a nitrogen atmosphere, the mixture is placed in a roller kiln for high-temperature sintering at 720℃±3℃ for 24 hours. The sintered product is then subjected to airflow pulverization and demagnetization sieving to obtain recycled lithium iron phosphate material.

[0108] Comparative Example 2 The discarded lithium iron phosphate battery cathode sheets or waste cathode sheets from battery factories are pulverized in the first stage by a mechanical impact mill. The main speed of the mechanical impact mill is 1200 RPM, and the internal classification speed is 800 RPM, resulting in a mixed material. The mixed material is then passed through a 200-mesh sieve, and the undersize material is further separated into two external classifications at a speed of 2800 RPM. The resulting product is lithium iron phosphate black powder.

[0109] Under air atmosphere, lithium iron phosphate black powder was placed in a rotary kiln preheated to 500℃ for oxidation and calcination, and held at that temperature for 8 hours. The compressed air parameters were 0.5MPa and 80Nm. 3 / h; After cooling, the oxidized and degummed mixture is obtained; then, the oxidized and degummed mixture is placed in a ribbon mixer, and glucose is added at 3% of the mass of the oxidized and degummed mixture. Lithium carbonate is added to the total Li content to 4.2% based on the lithium content of the scrapped lithium iron phosphate battery cathode sheet or the waste cathode sheet from the battery factory. The ribbon mixer is stirred at a speed of 20 RPM for 30 minutes to obtain the mixture; under nitrogen atmosphere protection, the mixture is placed in a roller kiln for high-temperature sintering at a temperature of 720℃±3℃ for 24 hours; the sintered product is then subjected to airflow pulverization and demagnetization screening to obtain regenerated lithium iron phosphate material.

[0110] In this application, the test results of the recycled lithium iron phosphate materials obtained according to Examples 1-4 and Comparative Examples 1-2 are shown in Table 1.

[0111] Table 1

[0112] Examples 1-2 are adopted Figure 2The table shows a specific method for regenerating lithium iron phosphate material. Comparative Example 1 is a corresponding prior art method for regenerating lithium iron phosphate material. As can be seen from Table 1, in Examples 1-2, after the conductive waste lithium iron phosphate batteries are crushed, the resulting fragments are sequentially subjected to oxidation calcination and color sorting to separate the positive electrode fragments, thereby removing C (graphite), Al (aluminum) and Cu (copper). However, Comparative Example 1 does not have this step. Therefore, the content of graphite, aluminum and copper in the regenerated lithium iron phosphate material obtained in Examples 1-2 in Table 1 is much lower than the content of graphite, aluminum and copper in the regenerated lithium iron phosphate material obtained in Comparative Example 1.

[0113] Examples 1-2 involve two-stage pulverization of lithium iron phosphate black powder using an air jet mill to deagglomerate secondary particles into single particles, resulting in pretreated lithium iron phosphate black powder. Subsequently, pretreated lithium iron phosphate black powder from different batches and applications of lithium iron phosphate batteries in different fields is uniformly mixed, so that the recycled lithium iron phosphate material produced by Examples 1-2 is not limited by source. However, this step was not performed in Comparative Example 1. As a result, the powder compaction density of the recycled lithium iron phosphate material obtained in Examples 1-2 in Table 1 is higher than that of the recycled lithium iron phosphate material in Comparative Example 1.

[0114] In Examples 1-2, a reducing agent was first added to a second mixture obtained by uniformly mixing multiple batches of pretreated lithium iron phosphate black powder to perform a reducing treatment on the second mixture, resulting in a reduced second mixture. Then, a substance containing a preset element was added to the reduced second mixture. These two steps repaired the lattice and electrochemical performance of the lithium iron phosphate black powder. However, in Comparative Example 1, only one step was involved in adding a substance containing a preset element to the lithium iron phosphate black powder. As a result, the initial reversible capacity and initial coulombic efficiency of the regenerated lithium iron phosphate material obtained in Examples 1-2 were much higher than those of the regenerated lithium iron phosphate material in Comparative Example 1.

[0115] Examples 3-4 are adopted Figure 3 Another specific method for regenerating lithium iron phosphate material is shown in Table 1. Comparative Example 2 is a corresponding prior art method for regenerating lithium iron phosphate material. As can be seen from Table 1, in Examples 3-4, lithium iron phosphate black powder is subjected to oxidation calcination and secondary crushing in sequence to obtain pretreated lithium iron phosphate black powder. Then, different batches of pretreated lithium iron phosphate black powder and those used in different fields of positive electrode sheets are uniformly mixed, so that the regenerated lithium iron phosphate material produced by Examples 3-4 is not limited by source. However, Comparative Example 2 does not have this step. Therefore, the powder compaction density of the regenerated lithium iron phosphate material obtained by Examples 3-4 in Table 1 is higher than that of the regenerated lithium iron phosphate material in Comparative Example 2.

[0116] In Examples 3-4, a reducing agent was first added to a second mixture obtained by uniformly mixing multiple batches of pretreated lithium iron phosphate black powder to perform a reducing treatment on the second mixture, resulting in a reduced second mixture. Then, a substance containing a preset element was added to the reduced second mixture. These two steps repaired the lattice and electrochemical performance of the lithium iron phosphate black powder. However, in Comparative Example 2, only one step was involved in adding a substance containing a preset element to the lithium iron phosphate black powder. As a result, the initial reversible capacity and initial coulombic efficiency of the regenerated lithium iron phosphate material obtained in Examples 3-4 were much higher than those of the regenerated lithium iron phosphate material in Comparative Example 2.

[0117] By applying the embodiments of this application, at least the following beneficial effects can be achieved: 1. In the lithium iron phosphate material regeneration method provided in this application embodiment, the lithium iron phosphate positive electrode sheet of the waste lithium iron phosphate battery is sequentially subjected to a first crushing, physical sieving, and air classification process to obtain lithium iron phosphate black powder; then, the lithium iron phosphate black powder is subjected to a second crushing to obtain pretreated lithium iron phosphate black powder; the pretreated lithium iron phosphate black powder from different bins is mixed evenly to obtain a second mixed material of a predetermined weight; subsequently, a substance containing a predetermined element is added to the second mixed material to obtain a third mixed material, and the third mixed material is subjected to high-temperature sintering and three-stage crushing to obtain regenerated lithium iron phosphate material; the secondary particles agglomerated in the lithium iron phosphate black powder are dispersed by the second crushing, so that the pretreated lithium iron phosphate black powder mainly consists of single particles with uniform particle size; then, the pretreated lithium iron phosphate black powder from different batches in different bins and applied in different fields is mixed evenly to achieve homogenization of raw material composition, thereby effectively eliminating material performance fluctuations caused by batch differences and application field differences, and improving the consistency and stability of regenerated lithium iron phosphate material.

[0118] Those skilled in the art will understand that the steps, measures, and solutions in the various operations, methods, and processes discussed in this application can be alternated, modified, combined, or deleted. Furthermore, other steps, measures, and solutions in the various operations, methods, and processes discussed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted. Furthermore, steps, measures, and solutions in related technologies that are similar to those disclosed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted.

[0119] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0120] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0121] The above description is only a partial implementation of this application. It should be noted that for those skilled in the art, other similar implementation methods based on the technical concept of this application, without departing from the technical concept of this application, also fall within the protection scope of the embodiments of this application.

Claims

1. A method for regenerating lithium iron phosphate material, characterized in that, include: The lithium iron phosphate positive electrode sheets of waste lithium iron phosphate batteries are subjected to primary crushing to obtain the first mixed material; The first mixture was subjected to physical sieving and air classification in sequence to obtain lithium iron phosphate black powder; The lithium iron phosphate black powder is subjected to two-stage pulverization to obtain pretreated lithium iron phosphate black powder; Pretreated lithium iron phosphate black powder from different silos is mixed evenly to obtain a second mixed material of a preset weight. Add a substance containing a preset element to the second mixture to obtain a third mixture; The third mixture is subjected to high-temperature sintering and three-stage pulverization to obtain recycled lithium iron phosphate material.

2. The regeneration method according to claim 1, characterized in that, Before the primary crushing of the lithium iron phosphate cathode sheets from waste lithium iron phosphate batteries to obtain the first mixed material, the process also includes: The charged, used lithium iron phosphate batteries are crushed to obtain fragments; The fragments are oxidized and calcined to oxidize some of the ferrous iron in the positive electrode sheet of the fragments to generate ferric iron, resulting in a fourth mixed material; the positive electrode sheet in the fourth mixed material is yellow; The positive electrode sheet was separated by color sorting; Furthermore, after uniformly mixing pretreated lithium iron phosphate black powder from different silos to obtain a second mixed material of a predetermined weight, and before adding a substance containing a predetermined element to the second mixed material to obtain a third mixed material, the process further includes: The second mixture is subjected to a reducing treatment.

3. The regeneration method according to claim 2, characterized in that, The second mixture is subjected to a reducing treatment, including: The second mixture is placed in a mixer. Under an inert atmosphere, a reducing agent solution is added to the mixer and stirred until the content of ferric iron in the mixer is equal to or less than the target content as determined by titration. Alternatively, sugars can be added to the second mixture, and high-temperature sintering can be carried out under an inert atmosphere.

4. The regeneration method according to claim 2, characterized in that, The size of the fragment is greater than or equal to 5 mm and less than or equal to 2 cm.

5. The regeneration method according to claim 1, characterized in that, After the first mixture is subjected to physical sieving and air classification to obtain lithium iron phosphate black powder; and before the lithium iron phosphate black powder is subjected to secondary pulverization to obtain pretreated lithium iron phosphate black powder, the process further includes: The lithium iron phosphate black powder is oxidized and calcined to remove carbon; Furthermore, after uniformly mixing pretreated lithium iron phosphate black powder from different silos to obtain a second mixed material of a predetermined weight; and before adding a substance containing a predetermined element to the second mixed material to obtain a third mixed material, the process further includes: The second mixture is subjected to a reducing treatment.

6. The regeneration method according to claim 5, characterized in that, The lithium iron phosphate black powder is oxidized and calcined to remove carbon, including: Calcium oxide particles with a particle size greater than 0.5 mm are added to the lithium iron phosphate black powder to obtain a fifth mixture; the amount of calcium oxide particles added includes 5% of the mass of the second mixture. The fifth mixture is added to the preheated calcining apparatus and kept at that temperature for 5-12 hours in an air or pure oxygen atmosphere; the preheating temperature of the calcining apparatus includes 400°C.

7. The regeneration method according to claim 6, characterized in that, The calcination apparatus includes a replaceable inner liner.

8. The regeneration method according to any one of claims 1-7, characterized in that, The median diameter of the pretreated lithium iron phosphate black powder is not less than 0.3 micrometers and not more than 5 micrometers.

9. A material for a lithium iron phosphate battery, characterized in that, It is manufactured based on the regeneration method described in any one of claims 1-8 above.

10. The material for a lithium iron phosphate battery according to claim 9, characterized in that, It also includes at least one of the following: The median diameter of the material in the lithium iron phosphate battery is greater than or equal to 0.8 micrometers and less than or equal to 2.5 micrometers; The compaction density of the lithium iron phosphate battery material is greater than or equal to 2.5 grams per cubic centimeter; At a charge / discharge rate of 0.1C, each gram of lithium iron phosphate material can release a capacity greater than or equal to 155 mAh.

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