Method for efficiently recycling and reusing lithium iron phosphate battery positive electrode waste material and application of lithium iron phosphate battery positive electrode waste material
By removing unnecessary components from the positive electrode waste of lithium iron phosphate battery, retaining lithium iron phosphate and conductive agents, forming reusable lithium iron phosphate powder, the problem of waste of positive electrode materials is solved and material utilization and battery performance are improved.
Patent Information
- Application Number
- CN202411668236.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-21
- Publication Date
- 2025-03-11
AI Technical Summary
During the coating process of the positive electrode material of lithium iron phosphate battery, the excess lithium iron phosphate slurry produced is mixed with the AT9 slurry, resulting in the inability to use again, resulting in a great waste of the positive electrode material.
Through sieving, dissolution, chemical reaction removal, drying and other operations, binder, hydrated alumina and organic solvents are removed from the positive electrode waste of lithium iron phosphate battery, and lithium iron phosphate and conductive agent are retained to form a reusable lithium iron phosphate powder.
It effectively improves the utilization rate of lithium iron phosphate positive electrode raw materials, reduces the production cost of lithium batteries, and the prepared lithium iron phosphate batteries have good circulation performance.
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Figure CN119601814A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of recycling positive electrode materials of lithium iron phosphate batteries, and in particular to a method and application for efficiently recycling and reusing positive electrode waste of lithium iron phosphate batteries. Background Art
[0002] Lithium iron phosphate battery is a battery that uses lithium iron phosphate (LiFePO 4 ) as the positive electrode material and carbon as the negative electrode material. Lithium iron phosphate batteries have the advantages of high operating voltage, high energy density, long cycle life, good safety performance, low self-discharge rate, and no memory effect. At the same time, lithium iron phosphate batteries do not contain harmful metals and are environmentally friendly. These characteristics make lithium iron phosphate batteries widely used in new energy vehicles, 5G communications, electric ships, energy storage systems and other fields.
[0003] The coating process of lithium iron phosphate positive electrode material is a key step in the manufacturing process of lithium-ion batteries. It involves evenly coating the lithium iron phosphate slurry formed by mixing the positive electrode material with a binder, a conductive agent, etc. on a metal current collector (usually aluminum foil), and applying a ceramic coating (AT9) on its edge to ensure the safety performance of the lithium iron phosphate battery. During the coating process of the lithium iron phosphate positive electrode material, excess lithium iron phosphate slurry will be discharged into the collection device, and a portion of the AT9 coating slurry will be mixed with the excess lithium iron phosphate slurry and enter the collection device, resulting in the collected lithium iron phosphate slurry being unable to be put into use again, and becoming lithium iron phosphate battery positive electrode waste, which causes a huge waste of lithium iron phosphate positive electrode materials.
[0004] Therefore, there is an urgent need for a method for efficiently recovering reusable lithium iron phosphate positive electrode materials from lithium iron phosphate battery positive electrode waste. Summary of the invention
[0005] In view of this, the purpose of this application is to provide a method and application for efficiently recycling and reusing lithium iron phosphate battery positive electrode waste. The method removes multiple components such as AT9 slurry from the mixed slurry collected in the coating process of lithium iron phosphate positive electrode materials, retains key raw materials such as lithium iron phosphate and conductive agent in the lithium iron phosphate battery positive electrode waste to the greatest extent, and further improves the utilization rate of lithium iron phosphate positive electrode raw materials.
[0006] In order to achieve or at least partially achieve the above objectives, the present application provides the following technical solutions:
[0007] In the first aspect, the present application provides a method and application for efficiently recycling and reusing positive electrode waste of lithium iron phosphate batteries, wherein the positive electrode waste of lithium iron phosphate batteries comprises lithium iron phosphate, a conductive agent, a binder, hydrated alumina (Al 2 O 3 ·nH 2O) and a first organic solvent; the method comprising the following steps:
[0008] (1) screening the lithium iron phosphate battery positive electrode waste through a first filter to remove the first organic solvent to obtain a first mixture;
[0009] (2) preparing a second organic solvent capable of dissolving the binder, and uniformly mixing the first mixture obtained in (1) with the second organic solvent to obtain a first mixed slurry;
[0010] (3) screening the first mixed slurry obtained in (2) through a second filter to remove the second organic solvent, and washing the remaining mixture with water to obtain a second mixture;
[0011] (4) mixing the second mixture obtained in (3) with a strong alkaline solution, and after the reaction is complete, obtaining a second mixed slurry;
[0012] (5) screening the second mixed slurry obtained in (4) through a third filter to remove the liquid component in the second mixed slurry, and washing the remaining mixture with water until the pH of the washed water is neutral, thereby obtaining a third mixture;
[0013] (6) Drying the third mixture under vacuum conditions to obtain lithium iron phosphate powder.
[0014] In a second aspect, the present application provides the application of the aforementioned method in the preparation of lithium iron phosphate positive electrodes and lithium iron phosphate batteries.
[0015] The present invention provides a method and application for efficiently recycling and reusing lithium iron phosphate battery positive electrode waste, which has at least the following beneficial effects compared with the prior art:
[0016] 1. The recycling method provided in this application can effectively remove the binder, hydrated aluminum oxide and organic solvent components in the positive electrode waste of lithium iron phosphate batteries, and obtain the key raw materials of lithium battery positive electrode materials: lithium iron phosphate and conductive agent, which improves the utilization rate of raw materials and reduces the production cost of lithium iron phosphate batteries. The recycled raw materials are used to make positive electrode materials for lithium iron phosphate batteries, and finally prepare lithium iron phosphate batteries, and the prepared lithium iron phosphate batteries have good cycle performance.
[0017] 2. The recovery method provided in this application is simple to operate, the treatment reagents can be used multiple times, are easy to process and recycle, and do not cause environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 A process flow chart for recycling and reusing lithium iron phosphate battery positive electrode waste provided in an embodiment of the present application.
[0019] Figure 2The present invention provides a comparison of the cycle performance of lithium iron phosphate batteries prepared with recycled lithium iron phosphate materials and original lithium iron phosphate materials. DETAILED DESCRIPTION
[0020] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.
[0021] Those skilled in the art will appreciate that, unless otherwise stated, the "said", "the", and "the aforementioned" used in the text of the present application may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present application means the presence of the features, steps, and operations, but does not exclude the presence or addition of one or more other features, integers, and steps.
[0022] In the text of this application, the terms "first", "second" and the like are used to distinguish between identical or similar items with substantially the same functions and effects. This is only for the purpose of clearly describing the technical solutions of the embodiments of this application, and shall not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.
[0023] Those skilled in the art will appreciate that, for any specific experimental steps or conditions not specified in the examples, the experiments may be carried out according to the conventional experimental steps or conditions described in the literature in the art; any raw materials or instruments used without specifying the manufacturer are conventional products that can be purchased commercially.
[0024] Those skilled in the art will understand that, unless otherwise specified in the present application, when a numerical range is given in an embodiment, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application are consistent with the prior art mastery of those skilled in the art and the records of this application, and any methods, equipment and materials of the prior art similar or equivalent to the methods, equipment and materials described in the embodiments of this application may also be used to implement this application.
[0025] During the coating process of lithium iron phosphate positive electrode materials, the collected excess lithium iron phosphate slurry will be mixed with AT9 slurry, resulting in the inability to reuse the lithium iron phosphate slurry, causing great waste. In order to improve the utilization rate of lithium iron phosphate slurry and save the cost of lithium battery preparation, this application forms a method for efficiently recovering lithium iron phosphate raw materials from lithium iron phosphate positive electrode waste through screening, dissolution, chemical reaction removal, drying and other operations. This method can effectively remove the binder, hydrated aluminum oxide, organic solvent and other components in the lithium iron phosphate positive electrode waste to obtain lithium iron phosphate powder, including lithium iron phosphate and conductive agent components. The obtained lithium iron phosphate powder can be used as a raw material for preparing lithium iron phosphate positive electrode materials.
[0026] Based on this, the embodiment of the present application provides a method and application for efficiently recycling and reusing positive electrode waste of lithium iron phosphate batteries, wherein the positive electrode waste of lithium iron phosphate batteries includes lithium iron phosphate, a conductive agent, a binder, hydrated aluminum oxide and a first organic solvent; the method comprises the following steps: (1) screening the positive electrode waste of lithium iron phosphate batteries with a first filter to remove the first organic solvent to obtain a first mixture; (2) preparing a second organic solvent capable of dissolving the binder, and uniformly mixing the first mixture obtained in (1) with the second organic solvent to obtain a first mixed slurry; (3) ) The first mixed slurry obtained in (2) is sieved through a second filter to remove the second organic solvent, and the remaining mixture is washed with water to obtain a second mixture; (4) The second mixture obtained in (3) is mixed with a strong alkaline solution, and after the reaction is complete, a second mixed slurry is obtained; (5) The second mixed slurry obtained in (4) is sieved through a third filter to remove the liquid component in the second mixed slurry, and the remaining mixture is washed with water until the pH of the washed water is neutral to obtain a third mixture; (6) The third mixture is dried under vacuum conditions to obtain lithium iron phosphate powder.
[0027] In the above embodiment, the positive electrode waste of the lithium iron phosphate battery is a mixture of lithium iron phosphate slurry and AT9 slurry. The lithium iron phosphate slurry is formed by mixing lithium iron phosphate with a conductive agent, a binder and an organic solvent to form a uniform slurry. The AT9 slurry is a uniform slurry formed by mixing hydrated alumina, a binder and an organic solvent. Therefore, the components of the positive electrode waste of the lithium iron phosphate battery include lithium iron phosphate, a conductive agent, a binder, an organic solvent and hydrated alumina. By removing the binder, organic solvent and hydrated alumina of the positive electrode waste of the lithium iron phosphate battery, the key raw materials for preparing the positive electrode of the lithium iron phosphate battery can be obtained.
[0028] In some embodiments, the conductive agent is at least one of SP conductive carbon black, acetylene black, carbon nanotube (CNT), and graphene.
[0029] In certain embodiments, the binder is polyvinylidene fluoride (PVDF).
[0030] In certain embodiments, the first organic solvent is N-methylpyrrolidone (NMP).
[0031] In certain embodiments, the second organic solvent in step (2) is dimethylacetamide (DMAc), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetramethylurea (C 5 H 12 N 2 O), triethyl phosphate (C 6 H 15 O 4 P), trimethoprim (C 14 H 18 N 4 O 3 ), at least one of acetone.
[0032] In certain preferred embodiments, in step (2), the second organic solvent is a mixture of dimethylformamide and acetone, wherein the mass ratio of dimethylformamide to acetone is 3:7.
[0033] In certain embodiments, the mixing temperature in steps (2) and (4) is 50-60° C., and the mixing time is 4-6 hours.
[0034] In some embodiments, the strong alkaline solution is a sodium hydroxide (NaOH) solution with a mass fraction of 36% to 45%. Hydrated aluminum oxide reacts with high concentration of sodium hydroxide to generate water-soluble sodium aluminate (NaAlO 2 ).
[0035] In some preferred embodiments, the strong alkali solution is a mixed alkali solution of sodium hydroxide solution and dimethylamine solution, wherein the mass fraction of the sodium hydroxide solution is 25% to 35%, and the mass fraction of the dimethylamine solution is 25% to 40%. If a high-concentration sodium hydroxide solution is used, the reaction will be more intense in the early stage. In addition, the high-concentration NaOH solution is highly corrosive and will corrode the skin if splashed on the skin. The safety is poor, and the operator often needs to wear protective gear, which is troublesome to operate.
[0036] Dimethylamine is a water-soluble base. The ionization equilibrium constant of dimethylamine in water is high, and it can be ionized into OH - and (CH 3 ) 2 NH 2 + The alkalinity is significantly lower than that of sodium hydroxide. By adding dimethylamine solution to a lower concentration of sodium hydroxide solution, when the OH in the mixed solution system - After being consumed by the reaction with hydrated alumina, dimethylamine will ionize to generate OH -It is replenished to ensure the continuation of the reaction and complete removal of hydrated alumina.
[0037] In some embodiments, the mesh sizes of the first filter screen, the second filter screen, and the third filter screen are 100-300.
[0038] In some embodiments, the drying temperature in step (6) is 180-210° C., and the drying time is 6-14 hours.
[0039] Based on this, the embodiments of the present application provide the application of the aforementioned method in the preparation of a lithium iron phosphate positive electrode and a lithium iron phosphate battery.
[0040] For easier understanding of the technical solution of this application, see Figure 1 Taking PVDF as the binder, NMP as the first organic solvent, a mixture of DMF and acetone as the second organic solvent, and sodium hydroxide as the strong base as an example, the process and principle of recovering lithium iron phosphate powder from lithium iron phosphate positive electrode waste provided by the present application are specifically described as follows:
[0041] In the process of coating the positive electrode with lithium iron phosphate slurry, waste materials including lithium iron phosphate, conductive agent, PVDF (as a binder), hydrated alumina and NMP (as the first organic solvent) are generated. After the waste is screened for the first time, NMP is removed, and the mixed substance remaining on the screen includes lithium iron phosphate, conductive agent, PVDF, hydrated alumina, that is, the first mixture; the first mixture is mixed with a second organic solvent formed by a mixture of DMF and acetone, and after PVDF is fully dissolved in the mixed solvent of DMF and acetone, the formed slurry (i.e., the first mixed slurry) is screened for the second time. At this time, the main substances remaining on the screen include lithium iron phosphate, conductive agent, hydrated alumina and a small amount of residual organic solvent. After washing with water for many times, the residual organic solvent (NMP, a mixed solvent of DMF and acetone containing PVDF) can be completely removed, and the mixture remaining on the screen is the second mixture; the second mixture is mixed with a NaOH solution, and the hydrated alumina in the second mixture reacts with sodium hydroxide to generate sodium aluminate (NaAlO 2), the slurry at this time includes lithium iron phosphate, a conductive agent, a solution including sodium aluminate and an excess of NaOH, i.e., the second mixed slurry; the second mixed slurry is screened for the third time, and what remains on the screen are mainly lithium iron phosphate, a conductive agent and residual solutions including sodium aluminate and NaOH, and then it is washed with water for several times again to remove the residual solution, and the pH value of the water after washing is measured. If it is neutral (pH=7), it means that the NaOH is completely removed, and if it is still alkaline (pH>7), the components of the mixture left on the screen with clean water are lithium iron phosphate, a conductive agent and residual water after washing, and finally the third mixture is dried to remove the water on the third mixture, that is, lithium iron phosphate powder containing lithium iron phosphate and conductive agent components is obtained, and an appropriate amount of binder is added and mixed with an organic solvent to prepare lithium iron phosphate slurry again for coating the positive electrode of a lithium battery.
[0042] The technical solution of the present application and the technical effects achieved are described in detail below through more specific embodiments.
[0043] Example 1
[0044] The present embodiment provides a method and application for efficiently recycling and reusing positive electrode waste of lithium iron phosphate batteries, wherein the positive electrode waste of lithium iron phosphate batteries includes lithium iron phosphate, SP conductive carbon black, carbon nanotubes (CNT), PVDF, hydrated alumina and NMP, wherein the mass ratio of lithium iron phosphate, SP conductive carbon black (hereinafter referred to as "SP") and carbon nanotubes (CNT) is 95:2:0.5; the specific steps of the method are as follows:
[0045] (1) sieving 50 kg of lithium iron phosphate battery positive electrode waste through a 200-mesh filter to remove the NMP solvent in the positive electrode waste to obtain a first mixture;
[0046] (2) preparing a mixed solvent of dimethylformamide and acetone at a mass ratio of 3:7, i.e., a second organic solvent, mixing the first mixture with the second organic solvent, and stirring with a double planetary mixer, wherein the mixing temperature is 55° C., the stirring speed is 25 rpm for revolution and 1000 rpm for rotation, and the stirring time is 6 hours, to obtain a first mixed slurry;
[0047] (3) The first mixed slurry obtained in (2) was sieved with a 200-mesh screen to remove the second organic solvent in the slurry, and the remaining mixture was washed three times with 50 kg of distilled water to obtain a second mixture.
[0048] (4) mixing the second mixture obtained in (3) with 50 kg of a 40% NaOH solution, and stirring with a double planetary mixer, wherein the mixing temperature is 55° C., the stirring speed is 25 rpm for revolution and 1000 rpm for rotation, and the stirring time is 6 h to obtain a second mixed slurry;
[0049] (5) sieving the second mixed slurry obtained in (4) through a 200-mesh filter to remove the liquid component in the slurry, and washing the remaining mixture with distilled water for multiple times until the pH value of the water after washing is neutral, thereby obtaining a third mixture;
[0050] (6) The third mixture obtained in (5) was dried under a vacuum condition of -95 KPa at a drying temperature of 200° C. for a drying time of 12 h, and finally a dry lithium iron phosphate powder was obtained.
[0051] Example 2
[0052] The present embodiment provides a method and application for efficiently recycling and reusing positive electrode waste of lithium iron phosphate batteries, wherein the positive electrode waste of lithium iron phosphate batteries includes lithium iron phosphate, SP conductive carbon black, carbon nanotubes (CNT), PVDF, hydrated alumina and NMP, wherein the mass ratio of lithium iron phosphate, SP conductive carbon black (hereinafter referred to as "SP") and carbon nanotubes (CNT) is 95:2:0.5; the specific steps of the method are as follows:
[0053] (1) sieving 50 kg of lithium iron phosphate battery positive electrode waste through a 200-mesh filter to remove the NMP solvent in the positive electrode waste to obtain a first mixture;
[0054] (2) preparing a mixed solvent of dimethylformamide and acetone at a mass ratio of 3:7, i.e., a second organic solvent, mixing the first mixture with the second organic solvent, and stirring with a double planetary mixer, wherein the mixing temperature is 55° C., the stirring speed is 25 rpm for revolution and 1000 rpm for rotation, and the stirring time is 6 hours, to obtain a first mixed slurry;
[0055] (3) The first mixed slurry obtained in (2) was sieved with a 200-mesh screen to remove the second organic solvent in the slurry, and the remaining mixture was washed three times with 50 kg of distilled water to obtain a second mixture.
[0056] (4) mixing the second mixture obtained in (3) with 50 kg of a 36% NaOH solution, and stirring with a double planetary mixer, wherein the mixing temperature is 55° C., the stirring speed is 25 rpm for revolution and 1000 rpm for rotation, and the stirring time is 6 h to obtain a second mixed slurry;
[0057] (5) sieving the second mixed slurry obtained in (4) through a 200-mesh filter to remove the liquid component in the slurry, and washing the remaining mixture with distilled water for multiple times until the pH value of the water after washing is neutral, thereby obtaining a third mixture;
[0058] (6) The third mixture obtained in (5) was dried under a vacuum condition of -95 KPa at a drying temperature of 200° C. for a drying time of 12 h, and finally a dry lithium iron phosphate powder was obtained.
[0059] Example 3
[0060] The present embodiment provides a method and application for efficiently recycling and reusing positive electrode waste of lithium iron phosphate batteries, wherein the positive electrode waste of lithium iron phosphate batteries includes lithium iron phosphate, SP conductive carbon black, carbon nanotubes (CNT), PVDF, hydrated alumina and NMP, wherein the mass ratio of lithium iron phosphate, SP conductive carbon black (hereinafter referred to as "SP") and carbon nanotubes (CNT) is 95:2:0.5; the specific steps of the method are as follows:
[0061] (1) sieving 50 kg of lithium iron phosphate battery positive electrode waste through a 200-mesh filter to remove the NMP solvent in the positive electrode waste to obtain a first mixture;
[0062] (2) preparing a mixed solvent of dimethylformamide and acetone at a mass ratio of 3:7, i.e., a second organic solvent, mixing the first mixture with the second organic solvent, and stirring with a double planetary mixer, wherein the mixing temperature is 55° C., the stirring speed is 25 rpm for revolution and 1000 rpm for rotation, and the stirring time is 6 hours, to obtain a first mixed slurry;
[0063] (3) The first mixed slurry obtained in (2) was sieved with a 200-mesh screen to remove the second organic solvent in the slurry, and the remaining mixture was washed three times with 50 kg of distilled water to obtain a second mixture.
[0064] (4) preparing 30 kg of a 30% by mass NaOH solution and 20 kg of a 30% by mass dimethylamine solution respectively, and mixing them together to form a mixed alkaline solution;
[0065] (5) mixing the second mixture obtained in (3) with the mixed alkaline solution obtained in (4), and stirring with a double planetary mixer, wherein the mixing temperature is 55° C., the stirring speed is 25 rpm for revolution and 1000 rpm for rotation, and the stirring time is 6 h, to obtain a second mixed slurry;
[0066] (5) sieving the second mixed slurry obtained in (4) through a 200-mesh filter to remove the liquid component in the slurry, and washing the remaining mixture with distilled water for multiple times until the pH value of the water after washing is neutral, thereby obtaining a third mixture;
[0067] (6) The third mixture obtained in (5) was dried under a vacuum condition of -95 KPa at a drying temperature of 200° C. for a drying time of 12 h, and finally a dry lithium iron phosphate powder was obtained.
[0068] Comparative Example 1
[0069] The originally prepared lithium iron phosphate positive electrode slurry is prepared, wherein lithium iron phosphate is used as an active raw material, SP conductive carbon black and carbon nanotubes (CNT) are used as mixed conductive agents, PVDF is used as a binder, and NMP is used as a solvent; the mass ratio thereof is: lithium iron phosphate: SP conductive carbon black: CNT: PVDF: NMP = 95:2:0.5:2.5:47.5.
[0070] Referring to the lithium iron phosphate positive electrode slurry of the comparative example, the missing components of the lithium iron phosphate powder obtained by the back-modification in the embodiment are supplemented, and then the lithium iron phosphate positive electrode slurry is prepared by the method of the original preparation of the lithium iron phosphate positive electrode slurry, and the specific steps are:
[0071] (1) Using NMP as a solvent, PVDF binder powder is added thereto and stirred for 5 hours to obtain PVDF glue. The glue needs to be vacuumed and left to stand for more than 12 hours to eliminate bubbles;
[0072] (2) Add the conductive agent SP and CNT into the PVDF glue solution, start the double planetary mixer, set the speed to 25 rpm for revolution and 800 rpm for rotation, and assist with NMP spraying to ensure that SP and CNT are fully mixed into the PVDF glue solution. The stirring time is 1 h;
[0073] (3) Add lithium iron phosphate in steps, first add 50%, then add the remaining 50% after stirring, to ensure that the lithium iron phosphate is effectively dispersed in the glue;
[0074] (4) After adding all the materials, the dispersion speed was increased to 1200 rpm, the orbital speed was kept unchanged, and stirring was continued for 1 hour. Then, the mixture was transferred to a transfer tank for vacuum defoaming treatment to complete the preparation of lithium iron phosphate positive electrode slurry.
[0075] The lithium iron phosphate positive electrode slurry prepared from the lithium iron phosphate powder recovered in the example and the lithium iron phosphate positive electrode slurry prepared in the comparative example were respectively subjected to positive electrode coating to prepare lithium iron phosphate battery positive electrode, and were respectively assembled into lithium iron phosphate batteries for cycle performance experiments to compare the battery capacity retention rates of the two. The lithium iron phosphate batteries prepared with the positive electrode material recovered in the example were numbered H1, H2, and H3, and the lithium iron phosphate battery prepared with the positive electrode material provided in the comparative example was numbered Y1.
[0076] Figure 2It is the cycle performance curve of four lithium iron phosphate batteries H1, H2, H3 and Y1. It can be seen from the figure that the capacity retention rate of the four lithium iron phosphate batteries H1, H2, H3 and Y1 has a basically consistent downward trend. After 100, 200, 300 and 390 charge and discharge cycles, the capacity retention rate results of H1, H2, H3 and Y1 are shown in Table 1 below.
[0077] Table 1
[0078]
[0079] It can be seen from the table that after 390 charge and discharge cycles, the capacity retention rates of H1, H2, and H3 are relatively high, which is comparable to the capacity retention rate of Y1, indicating that the lithium iron phosphate positive electrode material recovered from the lithium iron phosphate positive electrode waste by the recovery method provided in the embodiment of the present application can be reused to prepare lithium iron phosphate batteries. It can also be seen from the results in the table that the use of a mixed alkaline solution of a relatively low concentration of sodium hydroxide solution and a dimethylamine solution can replace a high concentration of sodium hydroxide solution as a strong alkaline solution to achieve high-quality recovery of lithium iron phosphate positive electrode materials, and further prepare a lithium iron phosphate battery with high cycle performance.
[0080] The present application is described 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 present application and its core ideas. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.
Claims
1. A method for efficiently recycling and reusing lithium iron phosphate battery positive electrode waste, characterized in that: The lithium iron phosphate battery positive electrode waste comprises lithium iron phosphate, a conductive agent, a binder, hydrated aluminum oxide and a first organic solvent; the method comprises the following steps: (1) screening the lithium iron phosphate battery positive electrode waste through a first filter to remove the first organic solvent to obtain a first mixture; (2) preparing a second organic solvent capable of dissolving the binder, and uniformly mixing the first mixture obtained in (1) with the second organic solvent to obtain a first mixed slurry; (3) screening the first mixed slurry obtained in (2) through a second filter to remove the second organic solvent, and washing the remaining mixture with water to obtain a second mixture; (4) mixing the second mixture obtained in (3) with a strong alkaline solution, and after the reaction is complete, obtaining a second mixed slurry; (5) Screening the second mixed slurry obtained in (4) through a third filter to remove the liquid component in the second mixed slurry, and washing the remaining mixture with water until the pH of the washed water is neutral to obtain a third mixture; (6) Drying the third mixture under vacuum conditions to obtain lithium iron phosphate powder.
2. The method according to claim 1, characterized in that: The conductive agent is at least one of SP conductive carbon black, acetylene black, CNT, and graphene, and the binder is polyvinylidene fluoride.
3. The method according to claim 1, characterized in that The first organic solvent is N-methylpyrrolidone; the second organic solvent is at least one of dimethylacetamide, dimethylformamide, dimethyl sulfoxide, tetramethyl urea, triethyl phosphate, trimethoprim, and acetone.
4. The method according to claim 3, characterized in that: The second organic solvent is a mixture of dimethylformamide and acetone, wherein the mass ratio of dimethylformamide to acetone is 3:
7.
5. The method according to claim 1, characterized in that: The mixing temperature in steps (2) and (4) is 50-60° C. and the mixing time is 4-6 hours.
6. The method according to claim 1, characterized in that The strong alkali solution is a sodium hydroxide solution with a mass fraction of 36% to 45%.
7. The method according to claim 1, characterized in that The strong alkali solution is a mixed alkali solution of sodium hydroxide solution and dimethylamine solution, wherein the mass fraction of the sodium hydroxide solution is 25% to 35%, and the mass fraction of the dimethylamine solution is 25% to 40%.
8. The method according to claim 1, characterized in that: The mesh numbers of the first filter screen, the second filter screen and the third filter screen are 100-300.
9. The method according to claim 1, characterized in that: In step (6), the drying temperature is 180-210° C. and the drying time is 6-14 h.
10. Use of the method according to any one of claims 1 to 9 in preparing lithium iron phosphate positive electrode and lithium iron phosphate battery.