Method for recycling phosphate batteries

Abstract

The present invention relates to a novel recycling route for batteries used in the field of electronic-electrical equipment and in the automotive field. The invention focuses on prismatic, cylindrical and pouch type batteries containing lithium iron phosphate LFP (LiFePO4) as active material. The method comprises the following steps: discharging the battery, disassembling and separating the battery components, grinding the battery cells, precipitating fluorine and lithium, leaching with acid, separating iron using precipitation and ion exchange resin, precipitating aluminum and precipitating the remaining lithium. The invention comprises the step of leaching with acid without the use of oxidizing agents, which allows values close to 99% efficiency for Li and Fe, and mechanical processing without any thermal treatment to concentrate the metals of interest from the battery cathode.

Description

Technical Field

[0001] This invention relates to a recycling method for lithium-ion batteries with lithium iron phosphate (LFP) (LiFePO4) active material, which are produced in the electronics and automotive sectors, using machining and hydrometallurgical routes for pouch, cylindrical and prismatic battery types. Background Technology

[0002] Lithium-ion batteries are a key technology used in electronic devices and electric vehicles. Due to the shift towards societies with lower greenhouse gas emissions, the consumption of these batteries for electric vehicles could increase by up to 10 times in capacity by 2030. Global consumption of lithium-ion batteries is estimated at $221 billion from 2015 to 2024.

[0003] Lithium is considered a critical and strategic element in the world's major economies. Demand for lithium will grow to the point where current mining output is insufficient to meet market demand, particularly for lithium-ion batteries. Therefore, seeking alternative sources of lithium becomes crucial, with recycling playing a vital role in promoting a circular economy. Another important aspect of lithium-ion batteries as a secondary source of lithium is the higher concentration of the element in batteries compared to its concentration in primary sources such as spodumene and lepidolite.

[0004] Improper disposal of batteries at the end of their service life can have serious negative impacts on the environment and society, leading to soil and water pollution and posing risks to human health. Therefore, it is necessary to properly dispose of these batteries to prevent environmental pollution.

[0005] The main differences between lithium-ion batteries lie in their model and the type of active material used. The model can be pouch, cylindrical, or prismatic, and the type can be LCO (LiCoO2), NCA (LiNiCoAlO2), or NMC (LiNiO2). x Mn y Co z O2 (where x+y+z=1) or LFP (LiFePO4) type.

[0006] Batteries with LFP (LiFePO4 – lithium iron phosphate) type active materials offer advantages over other lithium-ion batteries used in large-scale electric vehicles or energy storage devices due to their low cost, non-toxicity, high capacity, thermal stability, and good charge-discharge cycle performance.

[0007] Despite the importance of LFP batteries, little or no progress has been made in their recycling. There are two traditional routes for recycling lithium-ion batteries: pyrometallurgy and hydrometallurgy. Pyrometallurgical processes involve high-temperature steps and need to be combined with hydrometallurgical routes to separate the metal and obtain a high-purity product (i.e., content higher than 95%). Another drawback of pyrometallurgical processes is that lithium is not recovered but lost in the slag generated during the high-temperature steps. Furthermore, current processes have low lithium recovery rates.

[0008] Existing hydrometallurgical processes for LFP batteries use thermal pretreatment, leaching (acid or alkaline leaching), and separation and purification steps to obtain the product. Among these steps, leaching is critical because it is in this step that the extraction of elements present in the active material occurs, and these elements then enter the aqueous phase. Therefore, separation and purification steps are required to obtain a high-purity product. This route has the advantages of lower energy consumption and lower greenhouse gas emissions.

[0009] Currently, lithium-ion battery recycling methods primarily focus on other battery types, such as LCO, NCA, and NMC. However, with the expanding use of LFP batteries in the automotive sector, the large vehicle market will increasingly be dominated by these batteries, necessitating their disposal at the end of their lifespan. To mitigate social and environmental impacts, recycled LFP batteries play a crucial role in promoting a circular economy by bringing key metals, such as lithium, back into the market.

[0010] Document US10919775 relates to the production of lithium carbonate from the recycling of LFP type batteries. In this method, the waste batteries are first milled, and the aluminum foil is separated from the cathode active material. After an acid leaching step (using an inorganic acid) with the addition of an oxidant, iron remains unleached, resulting in a lithium-only solution.

[0011] Document CN105119024A reports a pretreatment step prior to the leaching step in the LFP cathode. Following this pretreatment step, the solid material is reacted with an acidic solution to leach lithium, followed by a precipitation step.

[0012] Document CN106848473B proposes using a calcination (heat treatment) step as a pretreatment for LFP batteries to remove aluminum, followed by a ball milling step for the lithium- and iron-containing material. The resulting material is then impregnated in an acidic medium with an added oxidant.

[0013] However, the recycling method for LFP-type lithium-ion batteries has unique characteristics compared to other lithium batteries, such as processing aluminum present in the current collector composition. Furthermore, the more selective leaching step for lithium still retains some leached iron. Therefore, separation and purification steps are required to remove aluminum and iron before obtaining lithium as a product.

[0014] Therefore, there is a gap in developing a recycling method specifically for LFP type lithium-ion batteries that is applicable to different battery forms, such as pouch, cylindrical and prismatic batteries, while providing reduced environmental impact, lower cost and technical feasibility. Summary of the Invention

[0015] The purpose of this invention

[0016] In this regard, the present invention aims to provide a recycling method for LFP (LiFePO4) batteries of pouch, cylindrical and prismatic types from the electronics and automotive sectors, the latter being the main focus of the present invention.

[0017] The present invention also aims to provide a physical processing method for LFP type batteries without any type of heat treatment and without the need for an oxidant in the leaching step.

[0018] Furthermore, the present invention aims to provide a physical processing method for LFP type batteries, and in the chemical processing, to separate iron and aluminum before obtaining lithium as a product. Invention Overview

[0020] Aspects and advantages of the invention will be set forth in part in the following description, and may be apparent from the description or may be learned by practice of the invention.

[0021] In a first embodiment, the recycling method for the lithium iron phosphate battery of the present invention includes the following steps:

[0022] - Discharge the battery to be recycled;

[0023] - Disassembly and separation of battery components, with separation carried out in groups: electronic parts and protective structures, and battery cells;

[0024] - Grinding the battery cell, wherein grinding is carried out in a cooling fluid;

[0025] - Separate the plastic parts of the battery cell from the ground material in the grinding step, where graphite and active materials remain in the process;

[0026] - Fluorine is precipitated from the solution from the separation step by adding Ca(OH)2 or CaCl2, wherein the precipitated fluorine is removed from the solution by a filtration step;

[0027] - Lithium is precipitated from the solution from the fluorine precipitation step by adding Na3PO4 or Na2CO3, wherein the precipitated lithium is removed from the solution by filtration;

[0028] - The solution from the lithium precipitation step is leached with acid;

[0029] - Filter the leachate solution to separate the leachate and solid materials;

[0030] - Separate filtered solid materials, including an external aluminum structure, aluminum foil, copper, and graphite;

[0031] - Iron is separated from the leachate from the filtration step by adding NaOH or Na2CO3;

[0032] - Residual iron is removed after the iron separation step, wherein the residual iron is removed using an ion exchange resin;

[0033] - Precipitate aluminum from the solution from the residual iron removal step by adding NaOH or Na2CO3;

[0034] - After aluminum precipitation, the remaining lithium is precipitated by crystallization or by adding at least one of sodium phosphate, sodium carbonate and calcium hydroxide.

[0035] In an alternative embodiment, the lithium iron phosphate battery recycling method of the present invention may include an additional step of separating aluminum by electrodialysis. This alternative embodiment of the present invention has the following characteristics:

[0036] - Following the residual iron removal step, aluminum is separated from the solution by electrodialysis using cation and anion membranes, wherein the electrodialysis is carried out in a current range of 200 mA to 400 mA and a reaction time of up to 30 hours, and wherein the aluminum concentrate solution undergoes an aluminum precipitation step.

[0037] The present invention can be used to resynthesize a recyclable lithium iron phosphate battery cathode. For this resynthesis, iron phosphate obtained by the methods disclosed herein is added to a lithium solution, the pH is adjusted to 5.0, and ascorbic acid is added at a concentration of up to 0.05 mol / L. The Li:Fe:PO4 ratio in the solution is adjusted by adding LiOH, Fe(OH)2, or LiPO4. The solution is then placed in a pressure reactor, where the mixture is stirred and heated to approximately 200°C for a reaction time of up to 6.0 hours. After this reaction, the final solution is filtered to obtain a LiFePO4 cathode.

[0038] This invention relates to a recycling method focused on LFP type lithium-ion batteries, which is applicable to different types of batteries, such as pouch, cylindrical and prismatic batteries, and has a smaller environmental impact, lower cost and technical feasibility. Attached Figure Description

[0039] A complete and practical description of the invention, including its best mode, is provided in the description with reference to the accompanying drawings, in which:

[0040] - Figure 1 A flowchart illustrating a first embodiment of the battery recycling method of the present invention is shown; and

[0041] - Figure 2 The illustration shows a flowchart of a second embodiment of the battery recycling method of the present invention. Detailed Implementation

[0042] Reference will now be made in detail to embodiments of the invention; one or more examples of which are illustrated in the accompanying drawings. Each example is provided to explain the invention and not to limit it. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to the invention without departing from its scope or spirit. For example, functions illustrated or described as part of some embodiments may be used with another embodiment to produce yet another embodiment. Therefore, the invention should be covered by such modifications and variations that exist within the scope of the appended claims and their equivalents.

[0043] Overall, such as Figure 1As can be seen, the LFP battery recycling method of the present invention, preferably for prismatic, cylindrical, and pouch-type batteries, involves the mechanical processing of the battery (without any heat treatment to concentrate the metal of interest from the battery cathode), comprising the following steps: discharging the battery to be recycled 101; disassembling and separating the battery components 102, wherein the separation is performed in groups: electronic components and protective structures, and battery cells; grinding the battery cells 103, wherein the grinding is performed in a cooling fluid (wet grinding, which avoids the risk of explosion, unlike existing processes), preferably water; separating the plastic parts of the battery cells from the ground material of the grinding step 103 104, wherein the plastic parts are washed and sieved 115, and graphite and active materials remain in the process. After the mechanical processing of the battery, there is the following step: precipitating fluorine from the solution obtained in the separation step 104 by adding Ca(OH)2 or CaCl2 105, wherein the precipitated fluorine is removed from the solution by a filtration step 116 using a filter with a pore size of 0.1 to 4 µm. Then, the following steps are performed: lithium is precipitated from the solution obtained in fluorine precipitation step 105 by adding Na3PO4 or Na2CO3, wherein the precipitated lithium is removed from the solution by filtration 117 using a filter with a pore size of 0.1 to 4 µm. Subsequently, the hydrometallurgical process of the present invention is started, comprising the steps of: leaching the solution obtained in lithium precipitation step 106 with acid leaching 107; and then filtering the leaching solution 108 to separate the leachate and solid material using a filter with a pore size of 0.1 to 4 µm. Following leaching 107, the following steps are performed: separating the filtered solid material 109, which includes an outer aluminum structure, aluminum foil, copper, and graphite; separating iron 110 from the leachate from filtration step 108 by adding NaOH or Na2CO3; removing residual iron 111 after iron separation step 110, wherein the residual iron is removed using an ion exchange resin; precipitating aluminum 112A from the solution from residual iron removal step 111 by adding NaOH or Na2CO3; and precipitating residual lithium 113 from the solution obtained from aluminum precipitation 112A by crystallization or by adding at least one of sodium phosphate, sodium carbonate, and calcium hydroxide.

[0044] The first step in the method is to discharge the battery to be recycled 101. Discharging is preferably performed in two resistive discharge stages to eliminate residual charge or recover electrical energy. Illustratively, discharge step 101 can be performed using a Ni-Cr resistor and a Cu resistor connected to the battery terminals in series or parallel, lasting 12 to 24 hours. Following this, the disassembly and separation 102 of the battery components occurs in two groups: electronic parts and protective structures, including plastic, aluminum, or steel; and the battery cells. The grinding 103 of the LFP battery cells, preferably cylindrical LFP cells, can be performed in a shredder or blade grinder while continuously adding coolant, preferably water (wet grinding, which avoids the risk of explosion, unlike existing processes). The battery cells are inserted into the grinder at intervals of 1 to 20 seconds between batches, and the ground material has a particle size of less than 50 mm. After grinding 103, the plastic material 104 is separated from the battery, which can be done by washing with water and by decantation, centrifugation, or a vibrating table. Separation can be achieved by sieving; the plastic parts of the battery cell (high-density and low-density polypropylene and polyethylene) are washed and sieved 115, and can be removed using sieves with a mesh size of 0.1 to 4 mm. Graphite and active materials then proceed to subsequent stages of the process. The removed plastic parts are washed to remove any remaining graphite (anode) from the plastic, and this wash water is reused in the stream destined for fluoride precipitation 105.

[0045] The solution, free of plastic material, then proceeds to the step of precipitating fluorine 105 with calcium hydroxide (Ca(OH)2) or calcium chloride (CaCl2). Ca(OH)2 or CaCl2 is added in amounts between stoichiometric and 20% excess, with a reaction time of up to 2.0 hours and a temperature ranging from 25°C to 90°C. The precipitated fluorine is removed from the solution by filtration step 116 using a filter with a pore size of 0.1 to 4 µm.

[0046] The next step is lithium precipitation step 106, in which lithium is precipitated by adding Na3PO4 or Na2CO3. Lithium precipitation is carried out by adding Na2CO3 in an amount between stoichiometric and 20% excess, for a reaction time of up to 2.0 hours, at a temperature in the range of 20°C to 80°C, and the lithium precipitation yield is at least 10%.

[0047] After lithium precipitation step 106, the precipitated lithium undergoes filtration step 117, and the water used for filtration can then be recycled in the method and can be returned and fed to grinding step 103.

[0048] The external structure of the battery cell (excluding plastic parts), graphite, active materials, and aluminum and copper foil present in solution since grinding step 103 proceed to impregnation step 107. In this step, sulfuric acid and citric acid can be used, with sulfuric acid preferred. The acid concentration varies from 0.2 mol / L to 4.0 mol / L, and the temperature ranges from 25°C to 90°C. The reaction time can vary from 0.5 to 5.0 hours. No oxidizing agent is used in the impregnation step. Due to the presence of the metallic aluminum foil in the battery cell, even without an oxidizing agent, the efficiency of the impregnation process of the present invention can reach 99% of the efficiency of the metal present in the active material. The efficiency of impregnation step 107 of the present invention can be seen in Table 1, which shows a comparison between results obtained by the currently claimed method and results obtained by prior art methods using oxidizing agents or other types of acids different from those used in the method of the present invention.

[0049] Table 1

[0050]

[0051] Reference from Table 1: (a): 99% aluminum was leached from the active material, and 70% aluminum was leached taking into account the active material and the current collector foil; *not reported.

[0052] Following the leaching step 107, a filtration step 108 is performed to remove solid materials (the external structure of the battery cell, aluminum foil, copper, and graphite) from the solution. The resulting liquid (aqueous phase) proceeds to a separation (purification) stage for the metals present, while the solid materials (leaching residue) proceed to a screening and panning step 109 (physical separation). In the screening and panning step 109, a screening step is performed to recover graphite, while the external structure of the battery cell, aluminum foil, and copper are recovered through a panning step. In the panning (which is carried out in a conventional panning apparatus), water is fed from the bottom of the tank (or column), aluminum foil exits from the top (overflow), and copper and the external structure of the battery cell exit from the bottom of the tank (underflow).

[0053] The liquid obtained in the leaching step contains metallic lithium, iron, and aluminum. The first step in separating these metals is the iron 110 separation step, carried out in a batch reactor using Na₂CO₃ or NaOH as a precipitant. Importantly, it should be noted that oxidants such as H₂O₂, air, or O₂ can be added to increase the redox potential (oxidation potential) of the solution from 0.3V to 0.7V to oxidize iron ions and facilitate precipitation; however, such oxidants are not used in the leaching step but are commonly used in the prior art. The precipitant (preferably Na₂CO₃) can be added in solid or solution form to achieve a concentration of up to 1.0 mol / L in the solution until the pH of the FePO₄ precipitation reaches the range of 1.5 to 3.5. The reaction is carried out over a time period of 0.25 to 4.0 hours and at a temperature range of 25°C to 80°C, wherein the obtained product FePO₄ is separated by filtration using a filter with a pore size of 0.1 to 4 µm.

[0054] It is worth noting that the presence of iron in aluminum hydroxide (Al(OH)3) precipitate impairs the final use of the product; therefore, it is essential to remove as much iron as possible to improve the purity of the subsequently obtained product. Thus, after the iron separation step 110, a step of removing residual iron 111 is performed using an ion exchange resin with a functional group selected from aminophosphonates, iminodiacetes, aminophosphonic acids, or bis-pyridinemethylamine, preferably aminophosphonic acids. The removal of residual iron 111 can be carried out in a batch process or preferably in a continuous system, such as an ion exchange column. In a batch removal process, approximately 10 L of solution is treated with 0.2 to 2.0 kg of resin at a pH of 2.0 to 3.0 and a temperature range of 25°C to 60°C for a reaction time of 0.5 to 6.0 hours. In a continuous system with ion exchange columns packed with resin connected in series for upward or downward flow, the flow rate is 0.5 to 5 bed volumes / hour, and the temperature is 25°C to 60°C. Preferably, a flow rate of 2 to 4 bed volumes per hour and a pH of 2.0 to 3.0 are used. For continuous systems, residual iron removal can also be carried out in a stirred reactor for 0.5 to 2.0 hours. By using residual iron removal step 111, all iron present in the solution is removed as ferric phosphate (FePO4) by filtration using a filter with a pore size of 0.1 to 4 µm.

[0055] The filtrate (solution) then proceeds to the aluminum precipitation step 112A, using Na₂CO₃ or NaOH in an amount ranging from stoichiometry to 40% excess, preferably Na₂CO₃, at a temperature range of 25°C to 80°C, a pH range of 3.0 to 7.0, and a reaction time of 0.5 to 3.0 hours. In this process, aluminum hydroxide and aluminum carbonate are obtained. After heat treatment at a temperature range of 200°C to 800°C for a reaction time of 1.0 to 5.0 hours, alumina is obtained.

[0056] Another proven feasible aluminum separation technique is electrodialysis. Figure 2 As illustrated in the embodiment, prior to the aluminum precipitation step 112A, the electrodialysis separation 112B of aluminum from the solution is carried out using both cation and anion exchange membranes, at a current range of 200 mA to 400 mA, for a reaction time of up to 30 hours. The concentrated aluminum solution then proceeds to the aluminum precipitation step 112A to obtain aluminum hydroxide, aluminum carbonate, or aluminum oxide, as previously explained.

[0057] Following the precipitation of iron and aluminum, different types of lithium products can be obtained from the solution. The remaining lithium precipitation step 113 can yield, for example: i) lithium sulfate, obtained by crystallizing the solution at a temperature range of 80°C to 110°C for a reaction time of 1.0 to 5.0 hours; ii) lithium phosphate, obtained by adding sodium phosphate in an amount between stoichiometric and 40% excess to the solution under stirring, at a temperature range of 25°C to 90°C for a reaction time of 1.0 to 5.0 hours; iii) lithium carbonate, obtained by adding solid or solution sodium carbonate at a concentration of 50 to 200 g / L under stirring, at a temperature range of 25°C to 90°C for a reaction time of 1.0 to 5.0 hours; iv) lithium hydroxide, obtained by adding calcium hydroxide at a concentration of 0.2 g / L to 1.0 g / L to the previously obtained lithium carbonate, at a temperature range of 25°C to 90°C for a reaction time of 1.0 to 5.0 hours. Lithium products are removed from the solution by filtration using filters with pore sizes ranging from 0.1 to 4 µm.

[0058] After the remaining lithium precipitation step 113, sodium sulfate crystals can still be obtained as a byproduct through a crystallization process, wherein, since the filtrate (solution) contains sodium sulfate, the solution is evaporated at a temperature of 90°C to 110°C and a reaction time of 1.0 to 5.0 hours. The acid used in leaching, which remains in the solution until the precipitated lithium is removed, can be returned to the leaching step 107. In this way, there is the advantage of avoiding the waste and disposal of acid used during leaching.

[0059] In the lithium iron phosphate battery recycling method 100 of the present invention, the filters used in the fluorine precipitation step 105, lithium precipitation step 106, iron separation step 110, residual iron removal step 111, leaching step 107, leaching solution filtration step 108, aluminum precipitation step 112A and residual lithium precipitation step 113 have a pore size of 0.1 to 4 µm, and are preferably of paper or membrane type.

[0060] The novel battery recycling method 100 of the present invention has a combination of method advantages, the following of which are particularly prominent:

[0061] - Discharge the battery without losing materials;

[0062] - No heat treatment steps are involved in the mechanical and chemical processing of batteries to be recycled;

[0063] - Grinding the battery in water;

[0064] - No oxidant is consumed in the leaching step;

[0065] - Obtain high-purity products from the active material of the battery cathode;

[0066] - The possibility of resynthesizing the cathode from the leaching solution or from the product obtained by the recycling method;

[0067] - Obtain the plastic, copper, aluminum and external structure of the battery through physical separation during battery recycling;

[0068] - An alternative to separating aluminum by electrodialysis after leaching;

[0069] - Avoid waste and disposal of acid used during leaching.

[0070] The LFP type lithium battery recycling method of the present invention enables the resynthesis of LFP battery cathodes. For the resynthesis of LFP battery cathodes, iron phosphate obtained after iron separation 110 and residual iron removal 111 is added to a lithium solution, the pH is adjusted to 5.0, and ascorbic acid at a concentration of up to 0.05 mol / L is added. The Li:Fe:PO4 ratio in the solution is adjusted by adding LiOH, Fe(OH)2, or LiPO4. The solution is then placed in a pressure reactor, where the mixture is stirred and heated to approximately 200°C for a reaction time of up to 6 hours. After this reaction, the final solution is filtered to obtain a LiFePO4 cathode.

[0071] This specification uses examples to describe the invention, including the best mode, and also enables any person skilled in the art to practice the invention, including producing and using any device or system and performing any incorporated method. The scope of the invention is defined by the claims, but may include other examples that may be conceived by a person skilled in the art. Such other examples are intended to be covered within the scope of the claims if they include structural elements that are not indistinguishable from the literal language of the claims, or if they include equivalent structural elements that are not substantially indistinguishable from the literal language of the claims.

Claims

1. A recycling method (100) for lithium iron phosphate batteries, characterized in that, It includes the following steps: Discharge the battery to be recycled (101). Disassembling and separating battery components (102), wherein the separation is performed in groups: electronic components and protective structures, and battery cells; The battery cell (103) is ground, wherein the grinding is performed in a coolant; (104) The plastic parts of the battery cell are separated from the ground material in the grinding step (103), wherein the graphite and active materials remain in the process; Fluorine is precipitated from the solution from the separation step (104) by adding Ca(OH)2 or CaCl2 (105), wherein the precipitated fluorine is removed from the solution by a filtration step (116); Lithium is precipitated from the solution from the fluorine precipitation step (105) by adding Na3PO4 or Na2CO3 (106), wherein the precipitated lithium is removed from the solution by filtration (117); The solution from the lithium precipitation step (106) is leached with acid (107); The leachate solution (108) is filtered to separate the leachate and solid material; Separate the filtered solid material (109), said filtered solid material including an external aluminum structure, aluminum foil, copper and graphite; Iron is separated from the leachate from the filtration step (108) by adding NaOH or Na2CO3 (110). After the iron separation step (110), the remaining iron is removed (111), wherein the remaining iron is removed using an ion exchange resin; Aluminum is precipitated from the solution from the residual iron removal step (111) by adding NaOH or Na2CO3 (112A). After aluminum precipitation, the remaining lithium is precipitated by crystallization or by adding at least one of sodium phosphate, sodium carbonate, and calcium hydroxide (113).

2. The recycling method (100) for lithium iron phosphate batteries according to claim 1, characterized in that, Recycled batteries are available in prismatic, cylindrical, and pouch types.

3. The recycling method (100) for lithium iron phosphate batteries according to claim 1 or 2, characterized in that, The discharge step (101) is carried out through two resistive discharge steps to recover the electrical energy released from the battery.

4. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, The grinding step (103) is carried out in a shredder or a blade grinder.

5. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, The grinding step (103) involves the continuous addition of a coolant (preferably water), wherein the battery cells are inserted into the grinder at intervals of 1 to 20 seconds between batches, and the ground material has a particle size of less than 50 mm.

6. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, The separation step (104) is performed by at least one of decantation, centrifugation and shaking table.

7. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, In the separation step (104), the plastic parts are separated by means of a sieve with a mesh size of 0.1 to 4 mm.

8. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, In the fluorine precipitation step (105), Ca(OH)2 or CaCl2 is added in stoichiometric amounts up to 20% excess, the reaction time is up to 2.0 hours, and the temperature is between 25°C and 90°C.

9. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, In the lithium precipitation step (106), Na2CO3 is added in stoichiometric amounts up to 20% excess, the reaction time is up to 2.0 hours, the temperature is 20°C to 80°C, and the lithium precipitation yield is at least 10%.

10. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that: The acid used in the impregnation step (107) is sulfuric acid or citric acid, wherein sulfuric acid is the preferred impregnating agent.

11. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, The impregnation step (107) is carried out in the absence of an oxidant.

12. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, The leaching step (107) has an acid concentration in the range of 0.2 mol / L to 4.0 mol / L, a temperature in the range of 25°C to 90°C, and a reaction time in the range of 0.5 to 5.0 hours.

13. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, The solid materials filtered out in the leaching solution filtration step (108) include graphite, residues from the external structure of the battery, copper sheets, and aluminum sheets.

14. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, The sieving in the solid material separation step (109) is performed using a sieve with a mesh size of 0.1 to 4 mm to separate the graphite from the solid material.

15. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, After sieving to separate the graphite, the panning in the solid material separation step (109) is carried out in a conventional panning apparatus, in which upward-flowing water is added to the column, and the external structure of the battery cell, aluminum foil and copper foil are recovered.

16. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, The iron separation step (110) is carried out in a pH range of 1.5 to 3.5, a temperature of 25°C to 80°C, and a reaction time of 0.25 to 4.0 hours, preferably using Na2CO3 added in solid or solution form to achieve a precipitant concentration of up to 1.0 mol / L in the solution.

17. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, In the residual iron removal step (111), the ion exchange resin used is preferably an ion exchange resin having aminophosphonic acid functional groups, and the residual iron removal step (111) is carried out in a batch process or preferably in a continuous system.

18. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, In the residual iron removal step (111) carried out in a batch process, the residual iron removal step (111) is carried out at a temperature range of 25°C to 60°C, a reaction time of 0.5 to 6.0 hours, and with 0.2 to 2 kg of resin added per 10 L of solution.

19. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, In the residual iron removal step (111) carried out in a continuous system, resin-filled columns connected in series are used, with an upward or downward flow, a flow rate of 0.5 to 5 bed volumes / hour, and a temperature range of 25°C to 60°C.

20. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, The aluminum precipitation step (112A) is carried out in a pH range of 3.5 to 7.0, a temperature of 25°C to 80°C, and a reaction time of 0.5 to 3.0 hours, and preferably uses an amount of Na2CO3 in stoichiometric proportions up to 40% excess, wherein the precipitated aluminum is separated from the solution by filtration.

21. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, The remaining lithium precipitation step (113) is performed in one of the following ways to obtain lithium in the form of Li2SO4, Li3PO4, Li2CO3 or LiOH: i) Crystallize the solution at a temperature of 80°C to 110°C for a reaction time of 1.0 to 5.0 hours to obtain lithium sulfate (Li2SO4). ii) Under stirring, an amount of sodium phosphate (solid or in solution) in stoichiometric excess of 40% is added to the solution, and lithium phosphate (Li3PO4) is obtained at a temperature of 25°C to 90°C for a reaction time of 1.0 to 5.0 hours. iii) Sodium carbonate is added to the solution at a concentration of 50 g / L to 200 g / L under stirring, and lithium carbonate (Li₂CO₃) is obtained at a temperature of 25°C to 90°C for a reaction time of 1.0 to 5.0 hours; or iv) Add calcium hydroxide to the lithium carbonate obtained in iii) at a concentration of 0.2 g / L to 1.0 g / L, and obtain lithium hydroxide (LiOH) at a temperature of 25°C to 90°C for a reaction time of 1.0 to 5.0 hours.

22. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, It further includes: Following the residual iron removal step (111), a step (112B) is performed to separate aluminum from the solution by electrodialysis using cation and anion membranes, wherein the electrodialysis is carried out in a current range of 200 mA to 400 mA and a reaction time of up to 30 hours, and wherein the aluminum concentrate solution is subjected to the aluminum precipitation step (112A).

23. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, After the remaining lithium precipitation step (113), the solution undergoes a crystallization step in which the solution is evaporated at a temperature of 90°C to 110°C and a reaction time of 1.0 to 5.0 hours to obtain sodium sulfate crystals, and the acid used in the leaching and still present in the solution is returned to the leaching step (107).

24. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, In the fluorine precipitation step (105), lithium precipitation step (106), leaching step (107), filtration step of the leaching solution (108), aluminum precipitation step (112A) and residual lithium precipitation step (113), the filters used have a pore size of 0.1 to 4 μm.

25. The recycling method (100) for lithium iron phosphate batteries according to any one of the preceding claims, characterized in that, The filters used are of the paper or membrane type.

Images