Method for preparing lithium supplement agent from lithium iron phosphate battery waste and lithium supplement agent
The Li3PO4 composite Li5FeO4 lithium supplement is prepared by oxidative roasting and secondary roasting of lithium iron phosphate battery waste, which solves the environmental protection and equipment loss problems in the recycling process of lithium iron phosphate battery waste and realizes efficient and environmentally friendly resource recycling.
Patent Information
- Application Number
- CN202511184498.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-22
- Publication Date
- 2025-10-17
AI Technical Summary
Existing methods for recycling waste lithium iron phosphate batteries have problems such as high environmental pressure, severe equipment loss, and difficulty in producing high value-added products.
Li3Fe2(PO4)3 and Fe2O3 mixed powder is prepared by oxidative roasting of lithium iron phosphate battery waste, and then mixed with lithium salt or Fe2O3 and roasted for the second time to prepare Li3PO4 composite Li5FeO4 lithium supplement, avoiding the generation of waste residue, waste water and waste acid.
The prepared Li3PO4 composite Li5FeO4 lithium supplement material has a high first charge specific capacity, suitable average particle size, and high compaction density. The entire process is environmentally friendly and pollution-free, realizing efficient recycling of resources.
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Figure CN120793860A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of battery waste treatment, in particular to a method for preparing lithium supplementing agent from lithium iron phosphate battery waste and the lithium supplementing agent. BACKGROUND
[0002] The service period of the first generation of new energy vehicles will soon be over, and the waste lithium iron phosphate batteries are increasing day by day. How to recycle valuable metals from waste batteries in an environmentally friendly and pollution-free manner and realize comprehensive recycling of resources is a problem that needs to be solved. The conventional treatment method for lithium iron phosphate battery waste is to dissolve and collect valuable metals such as lithium, copper and iron by means of leaching, extraction and other conventional hydrometallurgical methods. The recovery process often involves the use of a large amount of acid, alkali and organic extraction liquid, which puts a lot of pressure on environmental protection and is prone to cause damage to equipment. Therefore, there is an urgent need to develop a new method for recycling lithium iron phosphate battery waste that is environmentally friendly and produces high-value products. SUMMARY
[0003] To solve the problems in the prior art, the main purpose of the present application is to provide a method for preparing lithium supplementing agent from lithium iron phosphate battery waste. The prepared Li5FeO4 lithium supplementing agent has high irreversible capacity and good compatibility with lithium battery electrode liquid, and can be applied to various lithium ion batteries such as lithium iron phosphate, ternary and lithium manganate.
[0004] To solve the above technical problems, according to one aspect of the present application, the present application provides the following technical scheme: A method for preparing lithium supplementing agent from lithium iron phosphate battery waste, comprising the following steps: S1, recovering lithium iron phosphate powder from lithium iron phosphate battery waste, and oxidizing and roasting the lithium iron phosphate powder to obtain a roasting product of Li3Fe2(PO4)3 and Fe2O3 mixed powder; S2, adding a certain amount of lithium salt and / or Fe2O3 to the obtained Li3Fe2(PO4)3 and Fe2O3 mixed powder and mixing, and then performing secondary roasting to obtain a lithium supplementing agent of Li3PO4 and Li5FeO4 after roasting, wherein the molar ratio of Li3PO4 to Li5FeO4 in the lithium supplementing agent is 1: (1-20).
[0005] Under the high temperature condition of step S1, the carbon powder on the surface of lithium iron phosphate can be removed, and this process avoids the decomposition of Fe 3+ into Fe 2+ .
[0006] Preferably, in step S1, the lithium iron phosphate battery waste is treated by a pyrolytic flotation method to directly recover the lithium iron phosphate powder. The lithium iron phosphate powder is ground and treated, and the average particle size of the powder after grinding and treatment is less than 90 mesh. Then, the powder after grinding and treatment is oxidized and roasted.
[0007] Preferably, in the step S1, the roasting atmosphere is air or oxygen atmosphere, the roasting temperature is 400-1200℃, and the roasting time is 1-24h.
[0008] Preferably, in the step S2, the roasting atmosphere is air or nitrogen or inert gas atmosphere, the roasting temperature is 400-1200℃, and the roasting time is 2-24h.
[0009] Preferably, in the step S2, the lithium salt comprises one or more of lithium carbonate, lithium hydroxide, lithium nitrate, lithium acetate, and lithium oxide. To solve the above technical problems, according to another aspect of the present application, the present application provides the following technical solutions: A Li3PO4 composite Li5FeO4 lithium supplement material is prepared by the method for preparing a lithium supplement material from lithium iron phosphate battery waste according to any one of the above.
[0010] The present application has the following advantages: The present application provides a method for preparing a lithium supplement material from lithium iron phosphate battery waste, which uses lithium iron phosphate battery waste as raw material, oxidizes the lithium iron phosphate in the lithium iron phosphate battery waste to obtain Li3Fe2(PO4)3 and Fe2O3 mixed powder, and then mixes the lithium salt and / or Fe2O3 and obtains the lithium supplement material of Li3PO4 composite Li5FeO4 through secondary roasting, wherein the first charge specific capacity of the Li3PO4 composite Li5FeO4 lithium supplement material is >600mAh / g, the average particle size is 5-10μm, and the compaction density is >1.4g / cm 3 The present application does not produce waste residue, waste water and waste acid, is environmentally friendly and pollution-free, and turns waste into treasure. BRIEF DESCRIPTION OF DRAWINGS
[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings shown.
[0012] Figure 1 The process flow chart for preparing the lithium supplement material of Li3PO4 composite Li5FeO4 according to the present application.
[0013] Figure 2 The XRD pattern of the lithium supplement material of Li3PO4 composite Li5FeO4 prepared in Example 3 of the present application.
[0014] The objectives, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION
[0015] The technical solutions in the embodiments will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.
[0016] Li5FeO4 is a new type of lithium ion battery positive electrode lithium supplement, which is a lithium metal oxide with a reverse fluorite structure. When charged to 4.2V, one LFO molecule can release up to 4 lithium ions, with a theoretical specific capacity of 867mAh / g. The irreversible capacity is high, and it is compatible with the current lithium battery binder system. As a positive electrode lithium supplement material, it has good application prospect.
[0017] Lithium phosphate (Li3PO4) as a good modification material has the characteristics of high chemical stability, good ion conductivity, high safety, good thermal stability, etc. In the application scenarios such as lithium ion batteries, it helps to transport lithium ions and improve battery performance. It will not decompose within a certain temperature range, reducing the risk of safety hazards due to overheating during use, such as reducing the possibility of thermal runaway in battery material applications.
[0018] The lithium iron phosphate battery waste mainly contains lithium iron phosphate (LiFePO4), carbon powder, aluminum scrap and copper scrap. The present application processes waste lithium iron phosphate battery waste by pyrolysis flotation method, thereby directly recycling lithium iron phosphate powder. The recycled lithium iron phosphate powder is calcined in a tube furnace, and the product after calcination is a mixture of Li3Fe2(PO4)3 and Fe2O3 powders. Subsequently, the Li3Fe2(PO4)3 and Fe2O3 mixed powders are subjected to secondary calcination with lithium salt and / or Fe2O3 in a tube furnace, and the lithium supplement material of Li3PO4 composite Li5FeO4 is obtained after calcination. Since Li5FeO4 has poor electrical conductivity, Li3PO4 is a good coating modification material, and the lithium supplement material of Li3PO4 composite Li5FeO4 can be directly obtained after secondary calcination. The entire process does not produce waste residue, waste water and waste acid, is environmentally friendly and pollution-free, and turns waste into treasure.
[0019] The following are the steps for recovering lithium iron phosphate powder from lithium iron phosphate battery waste using pyrolysis flotation. First, the separated waste is placed in a pyrolysis furnace, the pyrolysis temperature is usually between 300-600℃, and it is carried out in an inert atmosphere such as nitrogen or argon. This can make the organic components in the positive electrode material, such as PVDF - polyvinylidene fluoride, etc. decompose and volatilize, leaving inorganic components such as lithium iron phosphate. The material after pyrolysis needs to be ground. Through grinding, the agglomerated particles are dispersed, and the lithium iron phosphate particles are better separated from other impurities, reaching the appropriate particle size, generally the smaller the particle size, the more conducive to subsequent flotation. Add a collector, such as oleic acid, which can selectively adsorb on the surface of lithium iron phosphate particles, making them hydrophobic. At the same time, add a foaming agent, such as pine oil, to produce stable bubbles. The ground material is added to the aqueous solution in the flotation tank to form a slurry. Then add flotation reagents, stir evenly, and then carry out aeration flotation. The bubbles carry the lithium iron phosphate particles with the collector to the surface of the slurry, while other hydrophilic impurities remain in the slurry. Collect the foam product on the surface of the flotation tank, which contains lithium iron phosphate. After several washes to remove residual reagents, filtration and drying, the recovered lithium iron phosphate powder is obtained.
[0020] The technical solutions of the present application are further described in conjunction with specific examples.
[0021] Example 1 A method for preparing a lithium supplement agent from lithium iron phosphate battery waste, comprising the following steps: S1, 1g of lithium iron phosphate powder in lithium iron phosphate battery waste is placed in a tube furnace, heated to 600℃ at a rate of 10℃ / min in air atmosphere, and kept at this temperature for 3 hours to obtain an orange red powder.
[0022] S2, 0.6g of lithium hydroxide is added to the calcined product obtained in S1, and ground in a mortar. After grinding to uniformity, it is placed in a tube furnace and heated to 600℃ at a rate of 10℃ / min in a nitrogen atmosphere, and kept at this temperature for 6 hours to obtain a lithium supplement agent material of Li3PO4 composite Li5FeO4 in a ratio of 1:1.
[0023] S3, the lithium supplement agent material of Li3PO4 composite Li5FeO4 in a ratio of 1:1 is mixed with conductive carbon black and binder in a mass ratio of 8:1:1, and NMP is used as the solvent. The mixture is ground thoroughly to form a uniform slurry. Then, the electrode sheet is prepared by coating film according to the usual method, and the button half-cell is assembled. The assembled battery is first placed at room temperature for 12 h, and then the electrochemical performance test is carried out. The results show that the initial charge specific capacity is 625.9 mAh / g.
[0024] Comparative Example 1 A method for preparing a lithium supplement agent from lithium iron phosphate battery waste, comprising the following steps: S1, grind the lithium iron phosphate powder in 1 g of lithium iron phosphate battery waste and 0.6 g of lithium hydroxide in a mortar, mix uniformly, then put into a tube furnace, heat to 600℃ at a speed of 10℃ / min under nitrogen atmosphere, and keep at this temperature for 9 hours to obtain a pre-lithiation agent Li5FeO4.
[0025] S2, mix the Li5FeO4 lithium supplement agent material obtained in step S1 with conductive carbon black and binder according to a mass ratio of 8:1:1, grind thoroughly with NMP as solvent to form a uniform slurry. Then coat the film according to the usual method to prepare an electrode sheet, and assemble a button half-cell. The completed battery is first placed at room temperature for 12 h, and then subjected to electrochemical performance test. The results show that the initial charge specific capacity is 610 mAh / g.
[0026] Example 2 A method for preparing a lithium supplement agent from lithium iron phosphate battery waste, comprising the following steps: S1, put the lithium iron phosphate powder in 1 g of lithium iron phosphate battery waste into a tube furnace, heat to 600℃ at a speed of 10℃ / min under air atmosphere, and keep at this temperature for 3 hours to obtain an orange-red powder.
[0027] S2, add 0.8 g of Fe2O3 and 1.5 g of lithium hydroxide to the calcined product obtained in S1, grind in a mortar, mix uniformly, then put into a tube furnace, heat to 600℃ at a speed of 10℃ / min under nitrogen atmosphere, and keep at this temperature for 6 hours to obtain a lithium supplement agent material of Li3PO4 composite Li5FeO4 in a ratio of 1:5.
[0028] S3, mix the lithium supplement agent material of Li3PO4 composite Li5FeO4 in a ratio of 1:5 with conductive carbon black and binder according to a mass ratio of 8:1:1, grind thoroughly with NMP as solvent to form a uniform slurry. Then coat the film according to the usual method to prepare an electrode sheet, and assemble a button half-cell. The completed battery is first placed at room temperature for 12 h, and then subjected to electrochemical performance test. The results show that the initial charge specific capacity is 635.8 mAh / g. Example 3 A method for preparing a lithium supplement agent from lithium iron phosphate battery waste, comprising the following steps: S1, put the lithium iron phosphate powder in 1 g of lithium iron phosphate battery waste into a tube furnace, heat to 600℃ at a speed of 10℃ / min under air atmosphere, and keep at this temperature for 3 hours to obtain an orange-red powder.
[0029] S2, 1.15 g of Fe2O3 and 3.2 g of lithium hydroxide were added to the calcination product obtained in S1, and grinding was performed in a mortar. After grinding until uniform mixing, the mixture was placed in a tube furnace, heated to 600°C at a rate of 10°C / min under a nitrogen atmosphere, and maintained at this temperature for 6 hours to obtain a lithium supplement material of Li3PO4 composite Li5FeO4 at a ratio of 1:10.
[0030] S3, the lithium supplement material of Li3PO4 composite Li5FeO4 at a ratio of 1:10 described above was mixed with conductive carbon black and a binder at a mass ratio of 8:1:1, and NMP was used as a solvent to sufficiently grind and form a uniform slurry. Subsequently, an electrode sheet was prepared by film coating in a conventional manner, and a button-type half cell was assembled. The cell after assembly was first left to stand at room temperature for 12 h, and then electrochemical performance testing was performed. The results showed that the initial charge specific capacity was 675.5 mAh / g. Comparative Example 2 A method for preparing a lithium supplement using lithium iron phosphate battery waste, comprising the following steps: S1, 1 g of lithium iron phosphate powder in lithium iron phosphate battery waste, 1.15 g of Fe2O3 and 3.2 g of lithium hydroxide were added and ground in a mortar. After grinding until uniform mixing, the mixture was placed in a tube furnace, heated to 600°C at a rate of 10°C / min under a nitrogen atmosphere, and maintained at this temperature for 9 hours to obtain a lithium supplement material.
[0031] S2, the lithium supplement material obtained in step S1 was mixed with conductive carbon black and a binder at a mass ratio of 8:1:1, and NMP was used as a solvent to sufficiently grind and form a uniform slurry. Subsequently, an electrode sheet was prepared by film coating in a conventional manner, and a button-type half cell was assembled. The cell after assembly was first left to stand at room temperature for 12 h, and then electrochemical performance testing was performed. The results showed that the initial charge specific capacity was 633.9 mAh / g.
[0032] Example 4 A method for preparing a lithium supplement using lithium iron phosphate battery waste, comprising the following steps: S1, the lithium iron phosphate powder in lithium iron phosphate battery waste was placed in a tube furnace, heated to 600°C at a rate of 10°C / min under an air atmosphere, and maintained at this temperature for 3 hours to obtain an orange-red powder.
[0033] S2, 1.15 g of Fe2O3 and 3.2 g of lithium hydroxide were added to the calcination product obtained in S1, and grinding was performed in a mortar. After grinding until uniform mixing, the mixture was placed in a tube furnace, heated to 600°C at a rate of 10°C / min under a nitrogen atmosphere, and maintained at this temperature for 6 hours to obtain a lithium supplement material of Li3PO4 composite Li5FeO4 at a ratio of 1:10.
[0034] S3, the lithium supplement material of Li3PO4 composite Li5FeO4 in the above ratio of 1:20 is mixed with conductive carbon black and binder in a mass ratio of 8:1:1, NMP is used as the solvent, and the mixture is ground thoroughly to form a uniform slurry. Then, the electrode sheet is prepared by film coating in the usual way, and the button-type half battery is assembled. The battery is first placed at room temperature for 12 h after assembly, and then the electrochemical performance test is carried out. The results show that the initial charge specific capacity is 656.9 mAh / g.
[0035] The initial charge-discharge specific capacity of Example 1, Example 2, Example 3, Example 4 is 625.9 mAh / g, 635.8 mAh / g, 675.5 mAh / g, 656.9 mAh / g respectively. Therefore, when the ratio of Li3PO4:Li5FeO4 is 1:10, the initial charge-discharge specific capacity is optimal. In Comparative Example 1, only one product of Li5FeO4 is obtained, and the XRD spectrum is shown in Figure 2. The results show that the initial charge-discharge specific capacity of Comparative Example 1 is 610 mAh / g, and the initial charge-discharge specific capacity of Comparative Example 2 is 633.9 mAh / g. The results show that the two-step calcination method is more optimal. Figure 2 It can be seen that the product obtained in Example 3 is Li3PO4 and Li5FeO4. The initial charge-discharge specific capacity of Comparative Example 1 and Comparative Example 2 is 610 mAh / g and 633.9 mAh / g respectively. The results show that the two-step calcination method is more optimal.
[0036] The above description is only the preferred embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation made according to the content of the present application, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.
Claims
1. A method for preparing a lithium supplement using lithium iron phosphate battery waste, characterized in that: The steps include: S1, recovering lithium iron phosphate powder from lithium iron phosphate battery waste, oxidizing and roasting the lithium iron phosphate powder to obtain a roasting product of Li3Fe2(PO4)3 and Fe2O3 mixed powder; S2. Add a certain amount of lithium salt and / or Fe2O3 to the obtained mixed powder of Li3Fe2(PO4)3 and Fe2O3, mix them, and then calcine them twice. After calcination, a lithium supplement comprising Li3PO4 and Li5FeO4 is obtained, wherein the molar ratio of Li3PO4 to Li5FeO4 in the lithium supplement is 1: (1-20).
2. The method for preparing a lithium supplement using waste lithium iron phosphate batteries according to claim 1, wherein: In step S1, lithium iron phosphate battery waste is treated by pyrolysis flotation to directly recover lithium iron phosphate powder; the lithium iron phosphate powder is ground, and the average particle size of the ground powder is less than 90 mesh; and the ground powder is then oxidized and roasted.
3. The method for preparing a lithium supplement using waste lithium iron phosphate batteries according to claim 1, wherein: In step S1, the calcination atmosphere is air or oxygen atmosphere, the calcination temperature is 400-1200° C., and the calcination time is 1-24 hours.
4. The method for preparing a lithium supplement using waste lithium iron phosphate batteries according to claim 1, wherein: In step S2, the calcination atmosphere is air, nitrogen or an inert gas atmosphere, the calcination temperature is 400-1200° C., and the calcination time is 2-24 hours.
5. The method for preparing a lithium supplement using waste lithium iron phosphate batteries according to claim 1, wherein: In step S2, the lithium salt includes one or more of lithium carbonate, lithium hydroxide, lithium nitrate, lithium acetate, and lithium oxide.
6. A lithium supplement comprising Li3PO4 and Li5FeO4, characterized in that: The method according to any one of claims 1 to 5 is used for preparation.