CN115259125A - Recovery and regeneration method of lithium iron phosphate reclaimed material and lithium iron phosphate material - Google Patents
Recovery and regeneration method of lithium iron phosphate reclaimed material and lithium iron phosphate material Download PDFInfo
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- CN115259125A CN115259125A CN202210087011.2A CN202210087011A CN115259125A CN 115259125 A CN115259125 A CN 115259125A CN 202210087011 A CN202210087011 A CN 202210087011A CN 115259125 A CN115259125 A CN 115259125A
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/45—Phosphates containing plural metal, or metal and ammonium
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/40—Electric properties
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/84—Recycling of batteries or fuel cells
Abstract
The invention provides a method for recycling a lithium iron phosphate reclaimed material and a lithium iron phosphate material. The method for recovering and regenerating the lithium iron phosphate reclaimed material can balance the lithium content in the lithium iron phosphate reclaimed material, avoid the problem of difficult lithium supplement process caused by large fluctuation of the lithium content in the lithium iron phosphate reclaimed material, and improve the process stability and batch stability of the lithium iron phosphate reclaimed material. In addition, the capacity and the cycle performance of the lithium iron phosphate reclaimed material obtained by the method for recovering and regenerating the lithium iron phosphate reclaimed material are obviously improved.
Description
Technical Field
The invention belongs to the technical field of battery production and manufacturing, and particularly relates to a recovery and regeneration method of a lithium iron phosphate reclaimed material and a lithium iron phosphate material.
Background
Lithium Ion Batteries (LIBs) have the advantages of high discharge voltage, long cycle life, no memory effect and the like, and are widely applied to portable electronic equipment, electric vehicles, electrochemical energy storage and other aspects. The rapid development of electric vehicles drives the explosive growth of power batteries, and lithium iron phosphate batteries (LFPBs) occupy a large amount of market shares due to the advantages of good safety, low cost, no toxicity and the like. The scrap quantity of the waste lithium iron phosphate batteries is increased year by year, and if the waste lithium iron phosphate batteries are not treated in time, the environment is polluted and a large amount of metal resources are wasted.
The method for recovering the anode material of the waste lithium iron phosphate battery mainly comprises a solid phase method, an acid leaching-precipitation method, a regenerated lithium iron phosphate method and the like, wherein the lithium iron phosphate roasting regeneration method utilizes an alkali solution to dissolve the lithium iron phosphate fine material so as to remove impurities and improve the purity; and adding a lithium source by adopting a solid phase method, and roasting, repairing and supplementing lithium to the lithium iron phosphate material in a lithium-deficient state in a nitrogen atmosphere to obtain a new lithium iron phosphate material. The method simplifies the treatment process, shortens the process flow, and reduces the pollution in the recovery process. However, the consistency of the lithium iron phosphate recycled material is greatly different due to the uneven use degree of the recycled batteries, the uneven discharge depth of the batteries during disassembly, the difference of the properties of raw materials of different manufacturers and the like, and great troubles are brought to lithium preparation in the regeneration process.
CN109704300A discloses a method for recycling a positive electrode material of a lithium iron phosphate battery, which comprises the following steps: (1) Removing shells of the waste lithium iron phosphate batteries after disassembly, putting the waste lithium iron phosphate batteries into hydrogen peroxide for ultrasonic oscillation and mechanical stirring, taking out aluminum foils, copper foils and diaphragms for direct recovery, and taking the rest parts as recovery liquid; (2) Adding a lithium source, an iron source and a phosphorus source into the recovered solution to obtain a mixed solution; (3) Adding citric acid and ammonia water into the mixed solution to form sol; (4) And mixing the sol-dried powder with a carbon source, ball-milling and calcining to obtain the lithium iron phosphate material.
CN112811404A discloses a recycling method of waste lithium iron phosphate anode powder, which comprises the following steps: (1) Mixing lithium iron phosphate anode powder with a first inorganic acid, a metal complexing agent and water to perform aluminum removal treatment, and filtering to obtain a lithium iron phosphate material after aluminum removal; (2) Mixing and pulping the aluminum-removed lithium iron phosphate material and a second inorganic acid, adding hydrogen peroxide for oxidation reaction, and filtering to obtain iron-phosphorus-containing filter residue; (3) Mixing the iron and phosphorus-containing filter residue and a third inorganic acid, pulping, dissolving, and filtering to remove graphite to obtain iron and phosphorus-containing filtrate; (4) And (3) regulating the pH value of the iron-phosphorus-containing filtrate by using alkali to react, separating out a precipitate, filtering and taking filter residue to obtain the iron phosphate.
CN113501510A discloses a method for recovering and regenerating a waste lithium iron phosphate battery positive electrode material, firstly, stripping a current collector of a waste lithium iron phosphate positive electrode sheet or a waste leftover material from an active material by using an organic solvent to obtain lithium iron phosphate powder; adding the obtained lithium iron phosphate powder into a mixed solution of a leaching agent and hydrogen peroxide for liquid-phase leaching, and filtering to obtain a lithium-containing filtrate and iron phosphate filter residues; removing impurities from the lithium-containing filtrate, evaporating and concentrating the lithium-containing filtrate, and adding a sodium carbonate solution to precipitate lithium element in the form of lithium carbonate to obtain battery-grade lithium carbonate; and (3) reversely washing the iron phosphate filter residue by using hydrochloric acid, drying and crushing to obtain the battery-grade iron phosphate.
The documents effectively realize the recycling of the waste lithium iron phosphate material, but the problems that the material components in the waste lithium iron phosphate material are not uniform, and the lithium content fluctuation is large, so that the lithium supplement process is difficult are not considered. Therefore, it is urgently needed to develop a recycling method capable of balancing the lithium content in the lithium iron phosphate reclaimed material.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method for recovering and regenerating a lithium iron phosphate reclaimed material and a lithium iron phosphate material, which can balance the lithium content in the lithium iron phosphate reclaimed material, avoid the problem of difficult lithium supplement process caused by large fluctuation of the lithium content in the lithium iron phosphate reclaimed material, and improve the process stability and batch stability of the lithium iron phosphate reclaimed material. In addition, the capacity and the cycle performance of the lithium iron phosphate reclaimed material obtained by the method for recovering and regenerating the lithium iron phosphate reclaimed material are obviously improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for recovering and regenerating a lithium iron phosphate reclaimed material, where the method includes:
mixing a lithium iron phosphate reclaimed material, phosphoric acid, lithium dihydrogen phosphate and lithium dihydrogen phosphate in a solvent to obtain a mixed solution, adding a hydrogen peroxide solution into the mixed solution for treatment to obtain a pretreatment slurry, and then sequentially supplementing lithium and calcining the pretreatment slurry to obtain the lithium iron phosphate reclaimed material.
According to the invention, the lithium content in different lithium iron phosphate reclaimed materials is balanced by the synergistic effect of adding phosphoric acid, lithium monohydrogen phosphate, lithium dihydrogen phosphate and hydrogen peroxide solution for treatment. The chemical potential of lithium in the system is adjusted by adding phosphoric acid, lithium monohydrogen phosphate and lithium dihydrogen phosphate, so that the transfer of lithium in the high-lithium-content particles to the solution is promoted, and the transfer of lithium in the low-lithium-content particles to the solution is inhibited; the hydrogen peroxide solution further promotes the speed of transferring lithium in the high-lithium-content particles into the solution, so that the time for balancing the lithium content in different lithium iron phosphate reclaimed materials is shortened, and the problem of large fluctuation of the lithium content is avoided.
In the invention, lithium in the lithium iron phosphate reclaimed material is partially leached by adopting a chemical leaching mode, so that fluctuation of lithium content in the lithium iron phosphate reclaimed material is balanced, and lithium in the lithium iron phosphate reclaimed material is not completely leached.
The method for recovering and regenerating the lithium iron phosphate reclaimed material can balance the lithium content in the lithium iron phosphate reclaimed material, avoid the problem of difficult lithium supplement process caused by large fluctuation of the lithium content in the lithium iron phosphate reclaimed material, and improve the process stability and batch stability of the lithium iron phosphate reclaimed material. In addition, the capacity and the cycle performance of the lithium iron phosphate reclaimed material obtained by the method for recovering and regenerating the lithium iron phosphate reclaimed material are obviously improved.
In a preferred embodiment of the present invention, the amount of the phosphoric acid added is 0 to 3wt% and is not 0, for example, 0.1wt%, 0.3wt%, 0.5wt%, 0.8wt%, 1wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2wt%, 2.3wt%, 2.5wt%, 2.8wt%, or 3wt%, based on 100wt% of the mass of the recovered lithium iron phosphate, but is not limited to the above-mentioned values, and other values not listed in the above-mentioned value range are also applicable.
Preferably, the lithium monohydrogen phosphate is added in an amount of 0 to 5wt% and not 0, for example, 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, or 5wt%, based on 100wt% of the mass of the recovered lithium iron phosphate, but is not limited to the recited values, and other values not recited within this range are also applicable.
Preferably, the lithium dihydrogen phosphate is added in an amount of 0 to 5wt% and not 0, for example, 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, or 5wt%, based on 100wt% of the mass of the recovered lithium iron phosphate, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
As a preferable technical scheme of the invention, the pH value of the mixed solution is adjusted before the hydrogen peroxide solution is added into the mixed solution.
Preferably, the pH of the mixed solution is adjusted to 2 to 6, for example, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5 or 6, but not limited to the recited values, and other values not recited within the range of values are also applicable.
The pH value of the mixed solution is limited to 2-6, and when the pH value is lower than 2, lithium iron phosphate can be partially dissolved, because the iron phosphate begins to dissolve in the solution with the pH value lower than 2; when the pH is higher than 6, a part of iron ions is precipitated to form iron hydroxide, since hydroxide accelerates the outward migration of iron ions.
The pH test of the obtained mixed solution is carried out, when the pH is lower than 2, lithium dihydrogen phosphate and/or lithium dihydrogen phosphate are/is added to adjust the pH of the mixed solution to be within the range of 2-6, and when the pH is higher than 6, phosphoric acid is added to adjust the pH of the mixed solution to be within the range of 2-6.
Preferably, the solvent comprises water or ethanol.
Preferably, the solvent is added in an amount of 30 to 100wt%, for example, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%, 95wt%, or 100wt%, based on 100wt% of the mass of the recovered lithium iron phosphate, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the mixing time is 0.5 to 6 hours, for example 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5 or 0.5 hour, but not limited to the recited values, and other values not recited in this range are equally applicable.
The invention limits the mixing time to be 0.5-6 h, when the mixing time is less than 0.5h, the mixing time is too short, which causes poor treatment effect, because the leaching of lithium is a diffusion process, and the process can be completed in a period of time; when the mixing time is longer than 6h, the specific surface area of the material is increased, because the acid solution has a slow etching effect on the surface of the lithium iron phosphate material, and the phenomenon that micropores appear on the surface is more serious the longer the contact time is.
Preferably, the mixing temperature is 50-80 ℃, for example 50 ℃, 52 ℃, 55 ℃, 58 ℃, 60 ℃, 62 ℃,65 ℃, 68 ℃,70 ℃, 72 ℃, 75 ℃, 78 ℃ or 80 ℃, but not limited to the enumerated values, and other non-enumerated values within the range of values are equally applicable.
The invention limits the mixing temperature to be 50-80 ℃, and when the temperature is lower than 50 ℃, the treatment effect is poor, because the diffusion speed of lithium at the low temperature is lower, so the treatment capability is lower; when the temperature is higher than 80 ℃, the lithium iron phosphate structure can be accelerated to dissolve, because the over-high temperature enhances the diffusion of iron ions, and the diffusion of the iron ions damages the lattice structure of the iron phosphate.
Preferably, the mixing is performed under stirring.
In a preferred embodiment of the present invention, the amount of the aqueous hydrogen peroxide solution added is 2 to 8wt%, for example, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, or 8wt%, based on 100wt% of the mass of the recovered lithium iron phosphate, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned value range are also applicable.
The addition amount of the hydrogen peroxide solution is lower and is only 2-8 wt%, because the hydrogen peroxide solution is not used for completely leaching lithium in the lithium iron phosphate reclaimed material, but plays a synergistic effect with phosphoric acid, lithium monohydrogen phosphate and lithium dihydrogen phosphate, and promotes the speed of transferring lithium in high-lithium-content particles into the solution, thereby achieving the effect of balancing the lithium content in different lithium iron phosphate reclaimed materials.
Preferably, the aqueous hydrogen peroxide solution has a mass concentration of 2 to 5wt%, and may be, for example, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, or 5wt%, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the time for the treatment by adding the hydrogen peroxide solution is 1 to 24 hours, for example, 1 hour, 2 hours, 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours or 24 hours, but the treatment is not limited to the enumerated values, and other values not enumerated in the numerical range are also applicable.
Preferably, the temperature of the treatment with the hydrogen peroxide solution is 50 to 80 ℃, for example, 50 ℃, 52 ℃, 55 ℃, 58 ℃, 60 ℃, 62 ℃,65 ℃, 68 ℃,70 ℃, 72 ℃, 75 ℃, 78 ℃ or 80 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the treatment with the addition of the aqueous hydrogen peroxide solution is carried out under stirring.
As a preferred technical solution of the present invention, the lithium supplementing process comprises:
and adding a lithium source, a carbon source and a dispersing agent into the pretreated slurry, stirring and mixing, and dispersing to obtain precursor slurry.
As a preferred embodiment of the present invention, the lithium source includes any one of lithium hydroxide, lithium carbonate, lithium citrate, or lithium acetate, or a combination of at least two of them.
Preferably, the lithium source is added in an amount of 0.5 to 20wt%, for example, 0.5wt%, 2wt%, 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt%, or 20wt%, based on 100wt% of the lithium iron phosphate reclaimed material, but the amount is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the carbon source comprises any one of glucose, citric acid, polyethylene glycol or sucrose or a combination of at least two thereof.
Preferably, the amount of the carbon source added is 0.5 to 3wt%, for example, 0.5wt%, 0.8wt%, 1wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2wt%, 2.3wt%, 2.5wt%, 2.8wt%, or 3wt%, based on 100wt% of the mass of the lithium iron phosphate regenerator, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the dispersant comprises one or a combination of at least two of allyl polyoxyethylene ether, methallyl alcohol polyoxyethylene ether or prenyl alcohol polyoxyethylene ether.
Preferably, the dispersant is added in an amount of 0.5 to 2wt%, for example, 0.5wt%, 0.6wt%, 0.8wt%, 1wt%, 1.2wt%, 1.4wt%, 1.6wt%, 1.8wt%, or 2wt%, based on 100wt% of the mass of the lithium iron phosphate reclaimed material, but is not limited to the recited values, and other values not recited in the range of the recited values are also applicable.
As a preferred embodiment of the present invention, the calcination process comprises:
and drying and crushing the precursor slurry in sequence, and then calcining to obtain the lithium iron phosphate reclaimed material.
According to the invention, operations such as separation and the like are not needed in the pretreatment slurry and the precursor slurry, the precursor slurry is directly dried and then calcined, and the lithium leached from the precursor slurry and the supplemented lithium return to the iron phosphate lattice again in the calcining process to form the lithium iron phosphate.
In a preferred embodiment of the present invention, the drying temperature is 70 to 250 ℃, and may be, for example, 70 ℃, 90 ℃, 110 ℃, 130 ℃, 150 ℃, 170 ℃, 190 ℃, 210 ℃, 230 ℃ or 250 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the calcination is carried out under an inert atmosphere.
Preferably, the inert atmosphere comprises nitrogen or argon.
Preferably, the calcination temperature is 650 to 850 ℃, for example 650 ℃, 670 ℃, 690 ℃,700 ℃, 720 ℃, 740 ℃, 760 ℃, 780 ℃,800 ℃, 820 ℃, 840 ℃ or 850 ℃, but is not limited to the recited values, and other values not recited in this range of values are equally applicable.
According to the invention, the lithium iron phosphate reclaimed material can be obtained by calcining at a lower temperature, and the migration of lithium ions can be enhanced at the lower calcining temperature, so that the utilization rate of a lithium source is improved.
Preferably, the calcination time is 2 to 12 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours or 12 hours, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
As a preferable embodiment of the present invention, the recovery and regeneration method includes:
(1) Stirring and mixing the lithium iron phosphate reclaimed material, phosphoric acid, lithium monohydrogen phosphate and lithium dihydrogen phosphate in a solvent for 0.5 to 6 hours at the temperature of between 50 and 80 ℃ to obtain a mixed solution, wherein the adding amount of the phosphoric acid is 0 to 3 weight percent and is not 0, based on the mass of the lithium iron phosphate reclaimed material as 100 weight percent; the addition amount of the lithium monohydrogen phosphate is 0-5 wt% and is not 0; the addition amount of the lithium dihydrogen phosphate is 0 to 5 weight percent and is not 0; the adding amount of the solvent is 30-100 wt%;
(2) Adjusting the pH value of the mixed solution obtained in the step (1) to 2-6, then adding a hydrogen peroxide solution with the mass concentration of 2-5 wt% at the temperature of 50-80 ℃, and stirring for 1-24 h to obtain a pretreatment slurry, wherein the adding amount of the hydrogen peroxide solution is 2-8 wt% based on the mass of the lithium iron phosphate reclaimed material as 100wt%;
(3) Adding a lithium source, a carbon source and a dispersing agent into the pretreated slurry obtained in the step (2), stirring and mixing, and dispersing to obtain precursor slurry, wherein the adding amount of the lithium source is 0.5-20 wt% based on 100wt% of the lithium iron phosphate reclaimed material; the adding amount of the carbon source is 0.5-3 wt% and the adding amount of the dispersing agent is 0.5-2 wt% based on the mass of the lithium iron phosphate reclaimed material as 100wt%;
(4) And (3) drying the precursor slurry obtained in the step (3) at the temperature of 70-250 ℃, crushing, and calcining for 2-12 hours at the temperature of 650-850 ℃ in an inert atmosphere to obtain the lithium iron phosphate reclaimed material.
In a second aspect, the invention provides a lithium iron phosphate material, which is prepared by the recycling method in the first aspect.
Compared with the prior art, the invention has the beneficial effects that:
the method for recycling the lithium iron phosphate reclaimed material can balance the lithium content in the lithium iron phosphate reclaimed material, avoid the problem of difficult lithium supplement process caused by large fluctuation of the lithium content in the lithium iron phosphate reclaimed material, and improve the process stability and batch stability of the lithium iron phosphate reclaimed material. In addition, the capacity and the cycle performance of the lithium iron phosphate reclaimed material obtained by the method for recovering and regenerating the lithium iron phosphate reclaimed material are obviously improved.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitation of the present invention.
Example 1
The embodiment provides a recovery and regeneration method of a lithium iron phosphate reclaimed material, which comprises the following steps:
(1) Stirring and mixing the lithium iron phosphate reclaimed material, phosphoric acid, lithium monohydrogen phosphate and lithium dihydrogen phosphate in water for 3 hours at the temperature of 60 ℃ to obtain a mixed solution, wherein the adding amount of the phosphoric acid is 1.5wt%, the adding amount of the lithium monohydrogen phosphate is 2wt%, the adding amount of the lithium dihydrogen phosphate is 3wt% and the adding amount of the water is 60wt% based on the mass of the lithium iron phosphate reclaimed material as 100wt%;
(2) Adjusting the pH value of the mixed solution obtained in the step (1) to 4, then adding a hydrogen peroxide solution with the mass concentration of 3wt% at the temperature of 60 ℃, stirring for 12 hours to obtain a pretreatment slurry, wherein the adding amount of the hydrogen peroxide solution is 5wt% based on 100wt% of the mass of the lithium iron phosphate reclaimed material;
(3) Adding lithium hydroxide, glucose and allyl polyoxyethylene ether into the pretreated slurry obtained in the step (2), stirring and mixing, and then dispersing at a high speed to obtain precursor slurry, wherein the adding amount of the lithium hydroxide is 10wt% based on 100wt% of the lithium iron phosphate reclaimed material; the adding amount of glucose is 2wt% and the adding amount of allyl polyoxyethylene ether is 1wt% based on the mass of the lithium iron phosphate reclaimed material being 100wt%;
(4) And (4) drying the precursor slurry obtained in the step (3) at the temperature of 150 ℃, crushing, and calcining for 8 hours at the temperature of 700 ℃ in a nitrogen atmosphere to obtain the lithium iron phosphate reclaimed material.
Example 2
The embodiment provides a recovery and regeneration method of a lithium iron phosphate reclaimed material, which comprises the following steps:
(1) Stirring and mixing the lithium iron phosphate reclaimed material, phosphoric acid, lithium monohydrogen phosphate and lithium dihydrogen phosphate in water for 2 hours at the temperature of 70 ℃ to obtain a mixed solution, wherein the adding amount of the phosphoric acid is 3wt%, the adding amount of the lithium monohydrogen phosphate is 4wt%, the adding amount of the lithium dihydrogen phosphate is 4wt% and the adding amount of the water is 100wt% based on the mass of the lithium iron phosphate reclaimed material;
(2) Adjusting the pH value of the mixed solution obtained in the step (1) to 2, then adding a hydrogen peroxide solution with the mass concentration of 5wt% at the temperature of 70 ℃, stirring for 3 hours to obtain a pretreatment slurry, wherein the adding amount of the hydrogen peroxide solution is 2wt% based on 100wt% of the mass of the lithium iron phosphate reclaimed material;
(3) Adding lithium carbonate, sucrose and methallyl alcohol polyoxyethylene ether into the pretreated slurry obtained in the step (2), stirring and mixing, and then dispersing at a high speed to obtain precursor slurry, wherein the adding amount of the lithium carbonate is 15wt% based on 100wt% of the mass of the lithium iron phosphate reclaimed material; the mass of the lithium iron phosphate reclaimed material is 100wt%, the addition of the sucrose is 0.5wt%, and the addition of the methallyl alcohol polyoxyethylene ether is 2wt%;
(4) And (3) drying the precursor slurry obtained in the step (3) at the temperature of 250 ℃, crushing, and calcining for 3 hours at the temperature of 800 ℃ in an argon atmosphere to obtain the lithium iron phosphate reclaimed material.
Example 3
The embodiment provides a recovery and regeneration method of a lithium iron phosphate reclaimed material, which comprises the following steps:
(1) Stirring and mixing the lithium iron phosphate reclaimed material, phosphoric acid, lithium monohydrogen phosphate and lithium dihydrogen phosphate in ethanol at the temperature of 50 ℃ for 6 hours to obtain a mixed solution, wherein the adding amount of the phosphoric acid is 2wt%, the adding amount of the lithium monohydrogen phosphate is 5wt%, the adding amount of the lithium dihydrogen phosphate is 5wt% and the adding amount of the ethanol is 80wt% based on 100wt% of the mass of the lithium iron phosphate reclaimed material;
(2) Adjusting the pH value of the mixed solution obtained in the step (1) to 6, then adding a hydrogen peroxide solution with the mass concentration of 2wt% at the temperature of 50 ℃, and stirring for 24 hours to obtain a pretreatment slurry, wherein the addition amount of the hydrogen peroxide solution is 8wt% based on 100wt% of the lithium iron phosphate reclaimed material;
(3) Adding lithium citrate, citric acid and prenyl polyoxyethylene ether into the pretreated slurry obtained in the step (2), stirring and mixing, and then dispersing at a high speed to obtain precursor slurry, wherein the adding amount of the lithium citrate is 0.5wt% based on 100wt% of the lithium iron phosphate reclaimed material; based on the mass of the lithium iron phosphate reclaimed material as 100wt%, the addition amount of the citric acid is 3wt%, and the addition amount of the prenyl alcohol polyoxyethylene ether is 0.5wt%;
(4) And (4) drying the precursor slurry obtained in the step (3) at the temperature of 200 ℃, crushing, and calcining for 12 hours at the temperature of 650 ℃ in an argon atmosphere to obtain the lithium iron phosphate reclaimed material.
Example 4
The embodiment provides a recovery and regeneration method of a lithium iron phosphate reclaimed material, which comprises the following steps:
(1) Stirring and mixing the lithium iron phosphate reclaimed material, phosphoric acid, lithium monohydrogen phosphate and lithium dihydrogen phosphate in ethanol at the temperature of 80 ℃ for 0.5h to obtain a mixed solution, wherein the adding amount of the phosphoric acid is 0.5wt%, the adding amount of the lithium monohydrogen phosphate is 0.5wt%, the adding amount of the lithium dihydrogen phosphate is 0.5wt%, and the adding amount of the ethanol is 30wt% based on 100wt% of the mass of the lithium iron phosphate reclaimed material;
(2) Adjusting the pH value of the mixed solution obtained in the step (1) to 5, then adding a hydrogen peroxide solution with the mass concentration of 2wt% at the temperature of 80 ℃, and stirring for 1h to obtain a pretreatment slurry, wherein the adding amount of the hydrogen peroxide solution is 6wt% based on 100wt% of the mass of the lithium iron phosphate reclaimed material;
(3) Adding lithium acetate, polyethylene glycol and prenyl polyoxyethylene ether into the pretreated slurry obtained in the step (2), stirring and mixing, and then dispersing at a high speed to obtain precursor slurry, wherein the adding amount of the lithium acetate is 20wt% based on 100wt% of the lithium iron phosphate reclaimed material; based on the mass of the lithium iron phosphate reclaimed material as 100wt%, the addition amount of polyethylene glycol is 1wt%, and the addition amount of prenyl polyoxyethylene ether is 2.5wt%;
(4) And (3) drying the precursor slurry obtained in the step (3) at the temperature of 70 ℃, crushing, and calcining for 2 hours at the temperature of 850 ℃ in a nitrogen atmosphere to obtain the lithium iron phosphate reclaimed material.
Example 5
The difference between this example and example 1 is that step (1) is to mix the reclaimed lithium iron phosphate, phosphoric acid, lithium monohydrogen phosphate and lithium dihydrogen phosphate in water at 40 ℃, and other process parameters and operation steps are the same as those in example 1.
Example 6
The difference between the embodiment and the embodiment 1 is that in the step (1), the reclaimed lithium iron phosphate, the phosphoric acid, the lithium monohydrogen phosphate and the lithium dihydrogen phosphate are stirred and mixed in water at the temperature of 90 ℃, and other process parameters and operation steps are the same as those in the embodiment 1.
Example 7
The difference between this example and example 1 is that in step (1), the reclaimed lithium iron phosphate, phosphoric acid, lithium monohydrogen phosphate and lithium dihydrogen phosphate are stirred and mixed in water for 0.3h to obtain a mixed solution, and other process parameters and operation steps are the same as those in example 1.
Example 8
The difference between this example and example 1 is that in step (1), the reclaimed lithium iron phosphate, phosphoric acid, lithium monohydrogen phosphate and lithium dihydrogen phosphate are stirred and mixed in water for 7 hours to obtain a mixed solution, and other process parameters and operation steps are the same as those in example 1.
Example 9
This example is different from example 1 in that the pH of the mixed solution was adjusted to 1 in step (2), and other process parameters and operation steps were the same as those of example 1.
Example 10
This example is different from example 1 in that the pH of the mixed solution was adjusted to 7 in step (2), and other process parameters and operation steps were the same as example 1.
Example 11
This example differs from example 1 in that in step (2) an aqueous hydrogen peroxide solution is added at 40 ℃ and the other process parameters and operating steps are the same as in example 1.
Example 12
This example differs from example 1 in that in step (2) an aqueous hydrogen peroxide solution is added at 90 ℃ and the other process parameters and operating steps are the same as in example 1.
Comparative example 1
This comparative example is different from example 1 in that the addition of the aqueous hydrogen peroxide solution was omitted in step (2), and the remaining process parameters and the operation steps were the same as those of example 1.
Comparative example 2
This comparative example is different from example 1 in that the process of adjusting the pH of the mixed solution in step (1) and step (2) is omitted and the remaining process parameters and the operation steps are the same as those of example 1.
Electrochemical performance tests were performed on the lithium iron phosphate regrind obtained in examples 1 to 12 and comparative examples 1 to 2:
(1) Preparing a positive pole piece: adding a lithium iron phosphate reclaimed material, an acetylene black conductive agent, polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) according to the mass ratio of 9.5.
(2) Assembling the battery: and (3) in a glove box, sequentially stacking the positive electrode shell, the positive electrode piece, the Celgard2400 diaphragm, the Guotai Huarong LB-303 electrolyte, the lithium sheet, the gasket, the spring piece and the negative electrode shell, and packaging to prepare the test battery.
(3) Cycle performance test parameters: and the cycle performance test is carried out by adopting a constant current charging and constant current discharging mode, the charging and discharging voltage range is 2.5-4.0V, and the charging and discharging current is 1C.
(5) Capacity performance test parameters: after the battery is assembled, standing for 10 hours, and carrying out capacity performance test by adopting a constant current charging and constant current discharging mode, wherein the charging and discharging voltage range is 2.5-4.0V, and the charging and discharging current is 0.1C.
The electrochemical performance test results of the lithium iron phosphate regenerants obtained in examples 1 to 12 and comparative examples 1 to 2 are shown in table 1.
TABLE 1
From the data of table 1, one can see:
(1) The lithium iron phosphate reclaimed materials in embodiments 1 to 4 are excellent in both capacity and cycle performance, which shows that the recovery and regeneration method for the lithium iron phosphate reclaimed material provided by the present invention can balance the lithium content in the lithium iron phosphate reclaimed material, avoid the problem of difficult lithium supplement process due to large fluctuation of the lithium content in the lithium iron phosphate reclaimed material, and improve the process stability and batch stability of the lithium iron phosphate reclaimed material, so that the obtained lithium iron phosphate reclaimed material is excellent in capacity and cycle performance.
(2) The capacity and cycle performance of the lithium iron phosphate reclaimed materials in example 5 and example 6 are lower than those in example 1, because the temperature for stirring and mixing the lithium iron phosphate reclaimed material, the phosphoric acid, the lithium monohydrogen phosphate and the lithium dihydrogen phosphate in the water is too low in example 5, and the temperature for stirring and mixing the lithium iron phosphate reclaimed material, the phosphoric acid, the lithium monohydrogen phosphate and the lithium dihydrogen phosphate in the water is too high in example 6. When the temperature is too low, the diffusion rate of lithium is low, thereby causing poor treatment effect; when the temperature is too high, the diffusion of iron ions is also enhanced, and the diffusion of the iron ions destroys the lattice structure of the iron phosphate, so that the lithium iron phosphate structure is dissolved quickly.
(3) The capacity and cycle performance of the recycled lithium iron phosphate material in examples 7 and 8 are lower than those of example 1, because the time for mixing the recycled lithium iron phosphate material, phosphoric acid, lithium monohydrogen phosphate and lithium dihydrogen phosphate in water is too short in example 7, and the time for mixing the recycled lithium iron phosphate material, phosphoric acid, lithium monohydrogen phosphate and lithium dihydrogen phosphate in water is too long in example 8. Because the leaching of lithium is a diffusion process, the processing effect is poor due to too short mixing time, the mixing time is too long, and the specific surface area of the material is increased because the acid solution has a slow etching effect on the surface of the lithium iron phosphate material and the phenomenon that micropores appear on the surface is more serious the longer the contact time is.
(4) The capacity and cycle performance of the lithium iron phosphate regenerant in example 9 and example 10 were lower than those of example 1, due to the too low pH of the mixed solution in example 9 and the too high pH of the mixed solution in example 10. When the pH value is too low, lithium iron phosphate is partially dissolved, and when the pH value is too high, hydroxide radicals accelerate outward migration of iron ions, so that partial iron ions are separated out to generate ferric hydroxide.
(5) The capacity and cycle performance of the lithium iron phosphate regenerant in example 11 and example 12 were lower than those of example 1, since the aqueous hydrogen peroxide solution was added at too low a temperature in example 11 and at too high a temperature in example 12. Therefore, the reaction temperature of the hydrogen peroxide solution and the mixed solution needs to be kept in a proper range, and the capacity and the cycle performance of the lithium iron phosphate regenerated material can be further improved.
(6) The capacity and cycle performance of the lithium iron phosphate regrind in comparative example 1 and comparative example 2 were lower than those of example 1, because the process of adding the hydrogen peroxide solution was omitted in comparative example 1, and the process of mixing the lithium iron phosphate regrind, phosphoric acid, lithium monohydrogen phosphate and lithium dihydrogen phosphate in water and the process of adjusting the pH of the mixed solution were omitted in comparative example 2. Therefore, the synergistic effect of the phosphoric acid, the lithium monohydrogen phosphate, the lithium dihydrogen phosphate and the hydrogen peroxide solution is added for treatment, so that the lithium content in different lithium iron phosphate reclaimed materials is balanced, the process stability and batch stability of the lithium iron phosphate reclaimed materials are improved, and the capacity and cycle performance of the lithium iron phosphate reclaimed materials are further improved.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method for recovering and regenerating a lithium iron phosphate reclaimed material is characterized by comprising the following steps:
mixing a lithium iron phosphate reclaimed material, phosphoric acid, lithium monohydrogen phosphate and lithium dihydrogen phosphate in a solvent to obtain a mixed solution, adding a hydrogen peroxide solution into the mixed solution for treatment to obtain a pretreatment slurry, and then sequentially supplementing lithium and calcining the pretreatment slurry to obtain the lithium iron phosphate reclaimed material.
2. The recovery and regeneration method according to claim 1, wherein the amount of phosphoric acid added is 0 to 3wt% and is not 0, based on 100wt% of the mass of the lithium iron phosphate reclaimed material;
preferably, the adding amount of the lithium dihydrogen phosphate is 0-5 wt% and is not 0, calculated by the mass of the lithium iron phosphate reclaimed material being 100wt%;
preferably, the addition amount of the lithium dihydrogen phosphate is 0-5 wt% and is not 0, based on 100wt% of the mass of the lithium iron phosphate reclaimed material.
3. The recovery and regeneration method according to claim 1 or 2, wherein the pH of the mixed solution is adjusted before the hydrogen peroxide solution is added to the mixed solution;
preferably, the pH of the mixed solution is adjusted to 2 to 6;
preferably, the solvent comprises water or ethanol;
preferably, the adding amount of the solvent is 30-100 wt% based on 100wt% of the mass of the lithium iron phosphate reclaimed material;
preferably, the mixing time is 0.5-6 h;
preferably, the temperature of the mixing is 50-80 ℃;
preferably, the mixing is performed under stirring.
4. The recovery and regeneration method according to any one of claims 1 to 3, wherein the amount of the hydrogen peroxide solution added is 2 to 8wt% based on 100wt% of the mass of the lithium iron phosphate reclaimed material;
preferably, the mass concentration of the hydrogen peroxide solution is 2-5 wt%;
preferably, the time for adding the hydrogen peroxide solution for treatment is 1-24 h;
preferably, the temperature for adding the hydrogen peroxide solution is 50-80 ℃;
preferably, the treatment with the addition of the aqueous hydrogen peroxide solution is carried out under stirring.
5. The recycling and regenerating method according to any one of claims 1 to 4, characterized in that the lithium supplementing process comprises:
and adding a lithium source, a carbon source and a dispersing agent into the pretreated slurry, stirring and mixing, and dispersing to obtain precursor slurry.
6. The recovery regeneration method according to claim 5, wherein the lithium source includes any one of lithium hydroxide, lithium carbonate, lithium citrate, or lithium acetate, or a combination of at least two thereof;
preferably, the adding amount of the lithium source is 0.5-20 wt% based on 100wt% of the mass of the lithium iron phosphate reclaimed material;
preferably, the carbon source comprises any one or a combination of at least two of glucose, citric acid, polyethylene glycol or sucrose;
preferably, the adding amount of the carbon source is 0.5-3 wt% based on 100wt% of the mass of the lithium iron phosphate reclaimed material;
preferably, the dispersant comprises one or a combination of at least two of allyl polyoxyethylene ether, methallyl alcohol polyoxyethylene ether or prenyl alcohol polyoxyethylene ether;
preferably, the addition amount of the dispersing agent is 0.5-2 wt% based on 100wt% of the mass of the lithium iron phosphate reclaimed material.
7. The recycling method according to claim 5 or 6, wherein the calcining comprises:
and drying and crushing the precursor slurry in sequence, and calcining to obtain the lithium iron phosphate regenerated material.
8. The recycling and regeneration method according to claim 7, wherein the temperature of the drying is 70 to 250 ℃;
preferably, the calcination is carried out under an inert atmosphere;
preferably, the inert atmosphere comprises nitrogen or argon;
preferably, the temperature of the calcination is 650-850 ℃;
preferably, the calcination time is 2 to 12 hours.
9. The recycling method according to any one of claims 1 to 8, wherein the recycling method comprises:
(1) Stirring and mixing the lithium iron phosphate reclaimed material, phosphoric acid, lithium monohydrogen phosphate and lithium dihydrogen phosphate in a solvent at the temperature of 50-80 ℃ for 0.5-6 h to obtain a mixed solution, wherein the adding amount of the phosphoric acid is 0-3 wt% and is not 0, based on the mass of the lithium iron phosphate reclaimed material as 100wt%; the addition amount of the lithium dihydrogen phosphate is 0 to 5 weight percent and is not 0; the addition amount of the lithium dihydrogen phosphate is 0 to 5 weight percent and is not 0; the adding amount of the solvent is 30-100 wt%;
(2) Adjusting the pH value of the mixed solution obtained in the step (1) to 2-6, then adding a hydrogen peroxide solution with the mass concentration of 2-5 wt% at the temperature of 50-80 ℃, and stirring for 1-24 h to obtain a pretreatment slurry, wherein the adding amount of the hydrogen peroxide solution is 2-8 wt% based on the mass of the lithium iron phosphate reclaimed material as 100wt%;
(3) Adding a lithium source, a carbon source and a dispersing agent into the pretreated slurry obtained in the step (2), stirring and mixing, and dispersing to obtain precursor slurry, wherein the adding amount of the lithium source is 0.5-20 wt% based on 100wt% of the mass of the lithium iron phosphate reclaimed material; the adding amount of the carbon source is 0.5-3 wt% and the adding amount of the dispersing agent is 0.5-2 wt% based on the mass of the lithium iron phosphate reclaimed material as 100wt%;
(4) And (3) drying the precursor slurry obtained in the step (3) at the temperature of 70-250 ℃, crushing, and calcining for 2-12 hours at the temperature of 650-850 ℃ in an inert atmosphere to obtain the lithium iron phosphate reclaimed material.
10. A lithium iron phosphate material, characterized in that the lithium iron phosphate material is prepared by the recovery and regeneration method of any one of claims 1 to 9.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109704300A (en) * | 2018-12-20 | 2019-05-03 | 成都新柯力化工科技有限公司 | A kind of method of lithium iron phosphate battery positive material recycling and reusing |
| CN109721043A (en) * | 2018-12-29 | 2019-05-07 | 宁德时代新能源科技股份有限公司 | Method for recycling and preparing lithium iron phosphate cathode material |
| WO2021102842A1 (en) * | 2019-11-28 | 2021-06-03 | 宁德时代新能源科技股份有限公司 | Method for producing lithium iron phosphate precursor by using retired lithium iron phosphate battery as raw material |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109704300A (en) * | 2018-12-20 | 2019-05-03 | 成都新柯力化工科技有限公司 | A kind of method of lithium iron phosphate battery positive material recycling and reusing |
| CN109721043A (en) * | 2018-12-29 | 2019-05-07 | 宁德时代新能源科技股份有限公司 | Method for recycling and preparing lithium iron phosphate cathode material |
| WO2021102842A1 (en) * | 2019-11-28 | 2021-06-03 | 宁德时代新能源科技股份有限公司 | Method for producing lithium iron phosphate precursor by using retired lithium iron phosphate battery as raw material |
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