Method for recycling positive electrode material of waste lithium iron phosphate battery at high value

Abstract

The invention relates to a method for high-value recovery of a positive electrode material of a waste lithium iron phosphate battery, which mainly comprises the following steps: adding a lithium iron phosphate positive electrode material, ammonium chloride and hydrogen peroxide into a ball milling tank for grinding, controlling the mass ratio of the ammonium chloride to the lithium iron phosphate positive electrode material to be 5: 2-7: 2, and controlling the volume mass ratio of the hydrogen peroxide to the lithium iron phosphate positive electrode material to be (18-22): 1mL / g; after grinding, washing out the mixture from the ball-milling tank by using deionized water, and then carrying out water leaching treatment to fully leach out metal lithium; excessive ammonium fluoride is added into the filtrate, and reaction liquid and a product lithium fluoride are obtained after reaction; and carrying out adsorption treatment on the reaction liquid by using defluorination resin, regenerating the defluorination resin through elution, combining and concentrating the collected effluent and eluent to obtain an ammonium chloride solution, and recycling the ammonium chloride solution to a chlorination reaction stage. According to the invention, through H2O2 reinforced mechanical chlorination coupling fluorination reaction, nearly total recovery of the waste lithium iron phosphate battery positive electrode material and high value of the product are realized, and the process is simpler and more environment-friendly.

Description

Technical Field

[0001] The invention relates to the technical field of recycling waste lithium iron phosphate batteries, and in particular to a method for recycling high-value positive electrode materials of waste lithium iron phosphate batteries. Background Art

[0002] Driven by the popularity of digital products and electric vehicles, the production of lithium-ion batteries has increased significantly in recent years. 4 ,LFP) batteries have attracted much attention due to their low cost, superior cycle performance, and enhanced safety. However, due to the high cost of existing recycling methods, large-scale recycling is still an obstacle. It can be seen that it is particularly important to improve the economic efficiency of lithium extraction technology from waste lithium iron phosphate to support the sustainability of the system. Therefore, the near-full recovery of waste LFP positive electrode materials and the high value of products are the main issues currently faced.

[0003] In the prior art, the methods for extracting valuable elements from waste LFP batteries are generally divided into complete leaching and selective leaching. Among them, the complete leaching process requires an acidic environment, usually using H 3 PO 4 or H 2 SO 4 Strong acid is maintained to dissolve all elements in LFP, and then separated according to their different properties. However, excessive acid is used in the leaching process, and the residual acid discharged into the water will cause serious pollution to the environment. In addition, the leached Li and Fe require additional steps to separate. Therefore, the complete leaching process has problems such as high recovery cost, long processing flow, poor leaching selectivity, and environmental pollution. The advantage of the selective leaching process is that it can be carried out under weakly acidic or neutral conditions, which can reduce costs and environmental impact.

[0004] With the development of technology, mechanochemical methods have been proven to destroy the LFP structure, reduce particle size, and improve metal leaching efficiency. For example, CN116573655A discloses a stripping and recovery method for lithium positive electrode materials in lithium iron phosphate batteries. In this technical solution, mechanical grinding is used to mix the obtained active positive electrode powder with a grinding agent and put it into an instrument for grinding. The metal ions in the grinding agent replace LiFePO 4The lithium in the battery is removed to generate LiCl, and a solid powder is obtained; after the grinding reaction is completed, the solid powder is transferred to a beaker filled with deionized water for leaching. After the leaching is completed, vacuum filtration is performed to achieve solid-liquid separation, and finally the metallic lithium is recovered in the form of lithium carbonate. For example, CN110760682 A discloses a process for selectively recovering lithium from waste lithium iron phosphate batteries by means of a mechanochemical activation method. The technical solution is to grind the positive electrode material and the grinding aid in a ball mill, and then add the leaching agent. After leaching for 1 hour, a lithium-containing solution and a leached residue containing iron, phosphorus and carbon powder are obtained. At this time, phosphorus and iron are combined to form an iron phosphate precipitate; the pH value of the lithium-containing solution is adjusted to 11-13 with sodium hydroxide, and then sodium phosphate is added, and the metallic lithium is recovered in the form of a precipitate of lithium phosphate. The above process relies on the high energy generated by mechanochemical activation to change the physicochemical properties of the substance and highly selectively leach lithium through the chemical reaction of the leaching agent. Compared with the complete leaching process, the amount of acid and other reagents is reduced and the process flow is simplified. However, the selectively leached metallic lithium is mainly recovered in the form of lithium carbonate or lithium phosphate. Since lithium carbonate or lithium phosphate still has a certain solubility in aqueous solution, the lithium recovery efficiency is still low. In addition, the amount of chemical additives and leaching agents such as ammonium chloride, carbonates and phosphates added during the reaction is large, and they cannot be recycled and reused, resulting in high recovery process costs and low added value of the recovered products. This is also the main reason why the technology is difficult to industrialize at present and a major challenge faced by enterprises.

[0005] Therefore, how to achieve near-full recycling of waste LFP positive electrode materials and increase the value of the products is a technical problem that urgently needs to be solved in the industry. Summary of the invention

[0006] The purpose of this application is to provide a method for recovering high-value positive electrode materials of waste lithium iron phosphate batteries by H 2 O 2 The enhanced mechanical chlorination coupled fluorination reaction achieves near-full recovery of waste lithium iron phosphate battery positive electrode materials and high value-added products.

[0007] The above invention objectives of the present application are achieved through the following technical solutions: A method for high-value recycling of waste lithium iron phosphate battery positive electrode materials, comprising the following steps: Step A, pre-treating the waste lithium iron phosphate battery to obtain a lithium iron phosphate positive electrode material; Step B, adding lithium iron phosphate positive electrode material, ammonium chloride and hydrogen peroxide into a ball mill for grinding, controlling the mass ratio of ammonium chloride to lithium iron phosphate positive electrode material to be 5:2-7:2, and the volume mass ratio of hydrogen peroxide to lithium iron phosphate positive electrode material to be (18-22): 1 mL / g; Step C: After grinding, the mixture is washed out of the ball mill with deionized water, and then subjected to water leaching to fully leach the metallic lithium; after the water leaching, the mixture is filtered to obtain a filtrate containing lithium chloride and a filter residue containing iron phosphate; wherein the filter residue is used for characterization experiments after washing, drying and grinding, and the filtrate, i.e., the leachate, is homogenized and then used to determine Fe by ICP-OES. 2+ / Fe 3+ and Li + Chlorination efficiency; Step D, adding an excess of ammonium fluoride to the filtrate of step C, reacting for a period of time, filtering to obtain a reaction solution and a precipitate, washing, drying, and grinding the precipitate to obtain a product, lithium fluoride; using ammonium fluoride as a precipitant, without introducing impurity ions, to achieve the conversion of LiCl to LiF, and washing, drying, and grinding the filtered LiF for characterization experiments; Step E, adjusting the pH of the reaction solution of step D to 5.0-6.5, then using a defluorination resin to perform a cyclic adsorption treatment on the reaction solution, and collecting the effluent; when the defluorination resin adsorption reaches saturation, using an aluminum chloride solution to elute and regenerate the defluorination resin, and collecting the eluate; combining the collected effluent and the eluate, and concentrating to obtain an ammonium chloride solution.

[0008] In the above technical solution, in step B, the ball-to-material ratio is (14-16):1, the grinding time is 11-13h, and the ball mill speed is 550-650rpm. By optimizing the above process conditions, the chlorination and recovery efficiency of metallic lithium is improved.

[0009] In the above technical solution, in step C, the leaching temperature is 55-65 degrees, and the leaching time is 60-100 minutes. When the leaching temperature is further increased, the Li leaching efficiency decreases, but the Fe leaching efficiency increases, which may accelerate the phase change or structural rearrangement of the positive electrode material at high temperature, resulting in the inhibition of Li diffusion. Considering energy consumption and economic benefits, the above temperature and time are selected to achieve the separation of Li and Fe.

[0010] In the above technical solution, in step E, the fluorine-removing resin is purchased from Xi'an Lanxiao Technology New Materials Co., Ltd., model LX-760.

[0011] In the above technical solution, in step E, a 10% aluminum chloride solution is used to elute and regenerate the defluorination resin at a flow rate of 1 BV / h, and the regeneration processing volume is 2 to 3 BV.

[0012] In the above technical solution, in step A, the pretreatment step is: discharging and disassembling the waste lithium iron phosphate battery, separating the positive electrode sheet, and then pyrolyzing the positive electrode sheet to separate the positive electrode material and aluminum foil, so as to obtain the lithium iron phosphate positive electrode material.

[0013] The technical concept of the present invention is as follows: First, ammonium chloride is added during the mechanical ball milling process to achieve partial chlorination of metallic lithium. Under natural ball milling conditions, only a small number of Li-O bonds will break, which is far from meeting the needs of Li chlorination and resource conversion. Therefore, H 2 O 2 The mechanical chlorination is strengthened to improve the chlorination efficiency of Li. After subsequent water leaching, Li is fully leached, while Fe is rarely leached, so that Li and Fe are separated to obtain a filtrate containing LiCl and a filtrate containing FePO. 4 of filter residue.

[0014] Secondly, the H of the present invention 2 O 2- NH 4 In the Cl mechanical chlorination reaction system, the chlorination reaction of ammonium chloride + ammonium fluoride is selected to couple the fluorination reaction. There are multiple considerations: on the one hand, ammonium chloride is selected to provide Cl for the metal Li to bind. - ions (chlorination reaction to form LiCl) and H produced by partial hydrolysis + ions make the solution weakly acidic, while H 2 O 2 Under weakly acidic conditions, its oxidation performance is greatly improved, and the divalent iron Fe 2+ Oxidized to ferric iron Fe 3+ , after oxidation, it will promote the breakage of Li-O bonds, causing Li to move from LiFePO 4 The structure is released, but the Fe-O bond is not greatly affected, thereby improving the chlorination efficiency of Li, while the chlorination efficiency of Fe is not affected, and the two can be separated later; on the other hand, by selecting ammonium fluoride, the chlorination-coupled fluorination reaction realizes the conversion of LiCl to the high-value product LiF, and the efficiency of recovering Li in the form of LiF is much higher than that of the existing technology using Li 2 CO 3 Or Li 2 PO 4 In the form of LiF, the added value, recovery rate and purity are higher than Li 2 CO 3 Or Li 2 PO 4 At the same time, the chlorination-fluorination reaction process also realizes the recycling and reuse of other raw materials: (1) The fluorination reaction, i.e., the conversion of LiF, can produce NH 4 F in the residual solution of Cl and LiF conversion - Through the ion exchange process of the defluorination resin, the functional groups on the resin will release an equal amount of Cl - , F - Adsorbed on the resin to remove F from the LiF conversion residue - , NH 4Cl was successfully derived; when the defluorination resin reached saturation, AlCl 3 The solution is regenerated, and the Al in the regenerated solution 3+ The F in the resin - desorbed to form Al-F complex, thus achieving resin regeneration and recycling; (2) the main solute of LiF conversion solution is converted into NH 4 Cl, this part of NH 4 Cl and the remaining NH 4 Cl and NH derived from the defluorination process 4 All Cl can be recycled and reused, which greatly reduces material consumption and reduces costs.

[0015] Again, H 2 O 2 The ability to enhance mechanical ball milling is known in the prior art, but in the H of the present invention 2 O 2- NH 4 In the mechanical chlorination reaction system of Cl, the inventor discovered for the first time through a large number of experiments that H 2 O 2 The mechanism of enhanced mechanical chlorination, i.e. H 2 O 2 The free radicals generated by the oxidation process [H 2 O 2 → OH → HO 2 →O 2 - → 1 O 2 】Maybe in LiFePO 4 However, the strong reactivity of these free radicals means that they have a short lifetime and are difficult to capture and quantify directly, which poses a great challenge to H 2 O 2 How to strengthen the formation and reaction mechanism of free radicals in the mechanical chlorination process of LFP poses a challenge, that is, which free radicals can strengthen the breaking of Li-O bonds without affecting the breaking of Fe-O bonds, and which free radicals can strengthen the breaking of Li-O bonds and Fe-O bonds at the same time. In this regard, the inventors thought of adding appropriate amounts of different types of quenchers: methanol (MeOH), n-butanol (NBA), tert-butyl alcohol (TBA), p-benzoquinone (BQ), and furfuryl alcohol (FFA). By comparing the chlorination efficiency of Li and Fe before and after the addition of quenchers, the existence and formation mechanism of free radicals were confirmed for the first time, and it was inferred that free radicals and LiFePO 4 reaction pathway.

[0016] In summary, this application achieves the following technical effects: The present invention adopts H 2O 2 Through enhanced mechanical chlorination coupled with fluorination reaction, 96.79% of Li was successfully converted into high-value product LiF with a purity of 99.50%. 99.89% of F was exchanged by defluorination resin. - 0.63 g of NH 4 Cl is recycled to the mechanical chlorination reaction. Thus, the nearly full recovery of waste lithium iron phosphate battery positive electrode materials and the high value of the product are achieved, and the process is simpler and more environmentally friendly. The present invention has a very good industrial application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a comparison chart of the chlorination efficiency of metal Li and Fe under different conditions.

[0018] Figure 2 It is a comparison chart of the chlorination efficiency of metal Li and Fe under different quenchers in Experimental Examples 1-5.

[0019] Figure 3 is LFP sample (a), H of comparative example 2 2 O-NH 4 Cl mechanical chlorination system produces filter residue sample (b), H 2 O 2 -NH 4 LFP sample (c) after ball milling in Cl mechanical chlorination system and H 2 O 2 -NH 4 XRD pattern of the filter residue sample (d) produced by the Cl mechanical chlorination system.

[0020] Figure 4 is LFP sample (a), H of comparative example 2 2 O-NH 4 Cl mechanical chlorination system produces filter residue sample (b), H 2 O 2 -NH 4 LFP sample (c) after ball milling in Cl mechanical chlorination system and H 2 O 2 -NH 4 FT-IR spectrum of the filter residue sample (d) produced by the Cl mechanical chlorination system.

[0021] Figure 5 is H of Example 1 2 O 2 -NH 4 XPS spectra of samples before and after ball milling in Cl mechanical chlorination system.

[0022] Figure 6 is H of Example 12 O 2 -NH 4 Relationship between Gibbs free energy change and temperature during mechanical chlorination of Cl (a), LiF (b), and repeated use of NH 4 Cl(c), Li 2 CO 3 (d) XRD pattern of.

[0023] Figure 7 It is a schematic diagram of the reaction mechanism of the method for recycling the positive electrode material of waste lithium iron phosphate batteries of the present invention. DETAILED DESCRIPTION

[0024] The present application is further described in detail below in conjunction with the accompanying drawings.

[0025] Experimental Materials: 1. Chemical reagents: Ammonium chloride (NH 4 Cl), hydrogen peroxide (H 2 O 2 , 30%), ammonium fluoride (NH 4 F); Fluorine-removing resin was purchased from Xi'an Lanxiao Technology New Materials Co., Ltd., model LX-760; Deionized water (resistivity: 18.2 MΩ·cm).

[0026] 2. Instruments and equipment: Planetary ball mill, purchased from Hunan Fucas Experimental Instrument Co., Ltd., model F-P400; An ion chromatograph (IC, Thermo Scientific ICS-1100, USA) was used; X-ray diffractometer (XRD, MalvernPanalytical Empyrean, The Netherlands); Fourier transform infrared spectrometer (FT-IR, Thermo Fisher Scientific Nicolet iS20, USA).

[0027] 3. Waste lithium iron phosphate batteries: The sample waste lithium iron phosphate battery of this embodiment is provided by a new energy and environmental protection technology company in Shenzhen.

[0028] The LFP positive electrode material is obtained by pre-treating the waste lithium iron phosphate battery. The element content of the LFP positive electrode material is shown in Table 1.

[0029] Table 1. Element content of LFP positive electrode materials element Fe Li P Al content% 33.89 4.12 17.48 0.19 The specific steps for pretreatment of waste lithium iron phosphate batteries are: First, discharge to 1V with Shenzhen Xinwei BTS-5V6A, then discharge with 5-10% NaCl solution for 48 hours. After the voltage is detected to be 0, disassemble the positive electrode sheet in an inert atmosphere glove box. After the positive electrode sheet is cut, it is placed in a tubular furnace for pyrolysis to remove PVDF. The pyrolysis conditions are pyrolysis temperature of 450℃, insulation time of 60min, and heating rate of 10℃ / min, so as to separate the aluminum foil and the positive electrode material and obtain lithium iron phosphate positive electrode material.

[0030] 0.1 g of lithium iron phosphate positive electrode material (hereinafter referred to as LFP) was taken as a sample and used in the following examples and comparative examples for experiments.

[0031] Embodiment 1: A method for high-value recycling of waste lithium iron phosphate battery positive electrode materials, comprising the following steps: Step A: pre-treat the waste lithium iron phosphate battery to obtain LFP for standby use.

[0032] Step B: 0.1 g of LFP was put into a 100 mL ball mill, and 0.3 g of ammonium chloride, 2.0 mL of hydrogen peroxide and a quencher were added for grinding. The ball-to-material ratio was controlled to be 15:1, the grinding time was 12 h, and the ball mill speed was 600 rpm; Among them, the mass ratio of ammonium chloride to LFP is 3:1, and the volume mass ratio of hydrogen peroxide to LFP is 20:1 mL / g; Step C: After grinding, the mixture is washed out of the ball mill with deionized water, and then subjected to water leaching treatment, the leaching temperature is 55 to 65 degrees, and the leaching time is 60 to 100 minutes, so that the metallic lithium is fully leached; after the leaching is completed, the filtrate is filtered to obtain a filtrate containing lithium chloride and a filter residue containing iron phosphate; wherein the filter residue is used for characterization experiments after washing, drying and grinding, and the filtrate, i.e., the leachate, is homogenized and used to determine Fe by ICP-OES. 2+ / Fe 3+ and Li + Chlorination efficiency.

[0033] Step D: adding an excess of ammonium fluoride to the filtrate of step C, using ammonium fluoride as a precipitant to achieve the conversion of LiCl to LiF without introducing impurity ions, filtering to obtain a reaction solution and a precipitate, washing, drying, and grinding the precipitate to obtain a product LiF, which is used for characterization experiments.

[0034] Step E, adjusting the pH of the reaction solution of step D to 5.0-6.5, then using the defluorination resin LX-760 to perform cyclic adsorption treatment on the reaction solution, and collecting the effluent; when the defluorination resin adsorption reaches saturation, using 10% aluminum chloride solution at a flow rate of 1BV / h to elute and regenerate the defluorination resin, the regeneration treatment volume is 2-3BV, and the eluate is collected; the collected effluent and the eluate are combined, and ammonium chloride is recovered after concentration treatment.

[0035] In this embodiment, the reaction solution obtained in step D contains two parts of NH 4 Cl: unreacted NH 4 NH generated during the conversion of Cl and LiF 4 Cl; these two parts of NH 4 Cl and NH derived from the defluorination process in step E 4 All Cl can be recovered and reused in the mechanical chlorination reaction stage of step B, thereby greatly reducing material consumption and reducing costs.

[0036] Result analysis: 96.79% of Li was successfully converted into high-value LiF with a purity of 99.50%. 99.89% of F was exchanged using fluorine removal resin LX-760 - 0.63 g of NH 4 Cl is recycled to the mechanical chlorination reaction in step B. 2 O 2 The enhanced mechanical chlorination coupled fluorination reaction achieves the near-full recovery of waste lithium iron phosphate battery cathode materials and high value-added products, and the process is simpler and more environmentally friendly.

[0037] Embodiment 2: A method for high-value recycling of waste lithium iron phosphate battery positive electrode materials, comprising the following steps: Step A: pre-treat the waste lithium iron phosphate battery to obtain LFP for standby use.

[0038] Step B: Take 0.1 g of LFP and put it into a 100 mL ball mill, and add 0.25 g of ammonium chloride, 1.8 mL of hydrogen peroxide and a quencher for grinding. The ball-to-material ratio is controlled to be 14:1, the grinding time is 13 h, and the ball mill speed is 550 rpm.

[0039] Step C: After grinding, the mixture is washed out of the ball mill with deionized water, and then subjected to water leaching treatment, the leaching temperature is 55 to 65 degrees, and the leaching time is 60 to 100 minutes, so that the metallic lithium is fully leached; after the leaching is completed, the filtrate is filtered to obtain a filtrate containing lithium chloride and a filter residue containing iron phosphate; wherein the filter residue is used for characterization experiments after washing, drying and grinding, and the filtrate, i.e., the leachate, is homogenized and used to determine Fe by ICP-OES.2+ / Fe 3+ and Li + Chlorination efficiency.

[0040] Step D: adding an excess of ammonium fluoride to the filtrate of step C, using ammonium fluoride as a precipitant to achieve the conversion of LiCl to LiF without introducing impurity ions, filtering to obtain a reaction solution and a precipitate, washing, drying, and grinding the precipitate to obtain a product LiF, which is used for characterization experiments.

[0041] Step E, adjusting the pH of the reaction solution of step D to 5.0-6.5, then using the defluorination resin LX-760 of Lanxiao Technology to perform cyclic adsorption treatment on the reaction solution, and collecting the effluent; when the adsorption of the defluorination resin reaches saturation, using 10% aluminum chloride solution at a flow rate of 1BV / h to elute and regenerate the defluorination resin, the regeneration treatment volume is 2-3BV, and the eluate is collected; the collected effluent and the eluate are combined, and ammonium chloride is recovered after concentration treatment.

[0042] Result analysis: 95.49% of Li was successfully converted into high-value LiF with a purity of 99.37%. 99.73% of F was exchanged using fluorine removal resin LX-760 - 0.62 g of NH 4 Cl is recycled to the mechanical chlorination reaction in step B.

[0043] Embodiment 3: A method for high-value recycling of waste lithium iron phosphate battery positive electrode materials, comprising the following steps: A method for high-value recycling of waste lithium iron phosphate battery positive electrode materials, comprising the following steps: Step A: pre-treat the waste lithium iron phosphate battery to obtain LFP for standby use.

[0044] Step B: Take 0.1 g of LFP and put it into a 100 mL ball mill, and add 0.35 g of ammonium chloride, 2.2 mL of hydrogen peroxide and a quencher for grinding. The ball-to-material ratio is controlled to be 16:1, the grinding time is 11 h, and the ball mill speed is 650 rpm.

[0045] Step C: After grinding, the mixture is washed out of the ball mill with deionized water, and then subjected to water leaching treatment, the leaching temperature is 55 to 65 degrees, and the leaching time is 60 to 100 minutes, so that the metallic lithium is fully leached; after the leaching is completed, the filtrate is filtered to obtain a filtrate containing lithium chloride and a filter residue containing iron phosphate; wherein the filter residue is used for characterization experiments after washing, drying and grinding, and the filtrate, i.e., the leachate, is homogenized and used to determine Fe by ICP-OES. 2+ / Fe 3+ and Li + Chlorination efficiency.

[0046] Step D: adding an excess of ammonium fluoride to the filtrate of step C, using ammonium fluoride as a precipitant to achieve the conversion of LiCl to LiF without introducing impurity ions, filtering to obtain a reaction solution and a precipitate, washing, drying, and grinding the precipitate to obtain a product LiF, which is used for characterization experiments.

[0047] Step E, adjusting the pH of the reaction solution of step D to 5.0-6.5, then using the defluorination resin LX-760 of Lanxiao Technology to perform cyclic adsorption treatment on the reaction solution, and collecting the effluent; when the adsorption of the defluorination resin reaches saturation, using 10% aluminum chloride solution at a flow rate of 1BV / h to elute and regenerate the defluorination resin, the regeneration treatment volume is 2-3BV, and the eluate is collected; the collected effluent and the eluate are combined, and ammonium chloride is recovered after concentration treatment.

[0048] Result analysis: 96.07% of Li was successfully converted into high-value LiF with a purity of 99.46%. 99.56% of F was exchanged using fluorine removal resin LX-760 - 0.61 g of NH 4 Cl is recycled to the mechanical chlorination reaction in step B.

[0049] Comparative Example: The main steps of the following comparative examples 1 and 2 are the same as those of Example 1, except that: Comparative Example 1 (H 2 O 2 -Mechanical system) In step B, 0.1 g of lithium iron phosphate positive electrode material was put into a 100 mL ball mill, and then 0.3 g of hydrogen peroxide was added for grinding; ammonium chloride was not used in this step.

[0050] Comparative Example 2 (H 2 O-NH 4 Cl mechanical chlorination system) In step B, 0.1 g of lithium iron phosphate positive electrode material was put into a 100 mL ball mill, and then 0.3 g of ammonium chloride and 2.0 mL of water were added for grinding; hydrogen peroxide was not used in this step.

[0051] Experimental example: The main steps of the following Experimental Examples 1-5 are the same as those of Example 1, except that the type of quencher in step B is different: The quenching agent in Experimental Example 1 is methanol (MeOH); The quenching agent in Experimental Example 2 is n-butanol (NBA); The quenching agent in Experimental Example 3 is tert-butyl alcohol (TBA); The quencher of Experimental Example 4 is p-benzoquinone (BQ); The quenching agent in Experimental Example 5 is furfuryl alcohol (FFA).

[0052] The above Examples 1 to 3, Comparative Examples 1 to 3 and Experimental Examples 1 to 5 were subjected to the following experiments respectively: 1. Detection method: 1. Inductively coupled plasma optical emission spectroscopy (ICP-OES, PerkinElmer Avio 550Max, USA) was used to measure the metal Fe in the filtrate after water immersion. 2+ / Fe 3+ and Li + The concentration of metals in LFP was calculated by the following formula (1): i : Among them C i and V i are the metal ion concentration (mg / L) and the filtrate volume (L), respectively. m and ω% are the mass of LFP (mg) and the mass fraction of metal in LFP, respectively.

[0053] 2. Determination of F in the LiF conversion residue using an ion chromatograph (IC, Thermo Scientific ICS-1100, USA) - concentration.

[0054] 3. X-ray diffractometer (XRD, Malvern Panalytical Empyrean, The Netherlands) was used for characterization, and data were collected by step scanning method with a scanning speed of 10° / min and a scanning angle (2θ) of 10° to 80°.

[0055] 4. Fourier transform infrared spectrometer (FT-IR, Thermo Fisher Scientific NicoletiS20, USA) was used to obtain the functional group information in the sample.

[0056] 5. The XPS spectra were obtained by X-ray photoelectron spectrometer (XPS, Thermo Fisher Escalab Xi+, USA).

[0057] 2. Experimental content: 1. Chlorination efficiency of metal Li and Fe under different conditions In order to improve the chlorination and recovery efficiency of Li, the ball-to-material ratio, NH 4 Cl to LFP mass ratio, H 2 O 2The effects of different process conditions such as volume, ball mill speed and grinding time on the chlorination efficiency of Li and Fe during mechanical chlorination were tested. The results are shown in Figure 2. Figure 1 shown.

[0058] Properly increasing the ball-to-material ratio helps improve the Li chlorination efficiency. More ZrO2 balls can increase the interface area and make the material force uniform. When the ball-to-material ratio is 15:1, the Li chlorination efficiency is 89.74% ( Figure 1 a). As the ball-to-material ratio continues to increase, the chlorination efficiency of Li begins to decrease, while the chlorination efficiency of Fe increases. This is because too many balls will cause agglomeration, which hinders the reaction.

[0059] NH 4 The influence of the mass ratio of Cl to LFP on the chlorination efficiency Figure 1 As shown in b. 4 When the mass ratio of Cl to LFP is 1:1, the chlorination efficiency of Li is 86.49% and the chlorination efficiency of Fe is 0.2%. When the mass ratio is 3:1, the Li chlorination efficiency increases to 97.14%, while the Fe chlorination efficiency is only 0.01%. However, when the mass ratio continues to increase, the chlorination efficiency of Li decreases slightly. This is because the reaction is a fluid-solid reaction and follows the shrinking core model. During the mechanical chlorination process, a liquid layer is formed around the solid particles, and the chlorination process of Li is a diffusion-controlled process. High concentrations of NH 4 Cl reduces the diffusion rate and hinders the chlorination process of Li. Considering the economic efficiency, NH 4 The optimal mass ratio of Cl to LFP is 3:1.

[0060] H 2 O 2 The effect of volume on chlorination efficiency is as follows Figure 1 c. The chlorination efficiency of Li increases with the increase of H 2 O 2 The chlorination efficiency of Li increased with the increase of H until 2.0 mL. At this time, the chlorination efficiency of Li reached 97.14%, while the chlorination efficiency of Fe decreased to 0.01%. 2 O 2 As the volume continues to increase, the chlorination efficiency of Li begins to decrease. During the experiment, it was found that an appropriate amount of liquid medium can prevent LFP from adhering to the inner wall of the ball mill and the surface of the balls, thereby promoting the mechanical chlorination reaction. However, too much liquid in the system will reduce the energy transfer during the ball milling impact. Therefore, H 2 O 2 The appropriate amount to be added is 2.0 mL.

[0061] In addition, the effect of ball milling speed on the chlorination efficiency of Li and Fe is reflected in Figure 1d. The Li chlorination efficiency reached 97.14% at 600 rpm and then decreased with the increase of the rotation speed. This is because the rotation speed is too high, part of the LFP material is brought to the blind spot of the ball mill, and the reaction is incomplete. Considering the energy consumption factor, 600 rpm is determined to be the ideal rotation speed for achieving high Li chlorination efficiency and low Fe chlorination efficiency.

[0062] Figure 1 e illustrates the effect of grinding time on the chlorination efficiency of Li and Fe. When the ball milling time is less than 9h, the chlorination efficiency of Li is about 80%. As the ball milling time continues to extend, the chlorination efficiency of Li is significantly improved. A critical point is reached after 12h of grinding, which is conducive to the separation of Li from the skeleton. After 12h of ball milling, the Li chlorination efficiency is 97.14%, and it does not increase with the increase of ball milling time. Excessive ball milling time will cause excessive crushing of the material and produce too many fine particles, which may cause material agglomeration or blockage in the reaction system, thereby reducing the chlorination efficiency of Li. Taking into account the time and economic costs, the ideal ball milling time was determined to be 12h.

[0063] In summary, the optimal conditions for selective chlorination determined in Example 1 are a pellet to material ratio of 15:1, NH 4 The mass ratio of Cl to LFP is 3:1, H 2 O 2 The volume mass ratio of LFP is 20:1 mL / g, the rotation speed is 600 rpm, and the grinding time is 12 h.

[0064] Meanwhile, the chlorination / leaching efficiencies of metallic lithium and iron in Comparative Examples 1 to 3 and Comparative Examples 1-2 are shown in Table 1.

[0065] Examples 1 to 3 In mechanical ball milling, H 2 O 2 Under the synergistic effect of the quencher, the chlorination efficiency of metallic lithium reached more than 95%, with the highest reaching 97.14%, while the chlorination efficiency of Fe reached 0.01% and was always below 0.1%.

[0066] Under the same leaching experimental conditions, Comparative Example 1 was a case where no NH 4 ClH 2 O 2 -Mechanical ball milling system, the leaching efficiency of Li was reduced to 40.07%, and the leaching efficiency of Fe was 1.88%. This shows that the use of NH 4 ClH 2 O 2 -NH 4 Cl mechanical chlorination system, NH 4 Cl plays an important role in enhancing the chlorination efficiency of Li. On the one hand, it provides Cl for metal Li to bind -ions (chlorination reaction to produce LiCl), while partial hydrolysis produces H + ions make the solution weakly acidic, while H 2 O 2 Under weakly acidic conditions, its oxidation performance is greatly improved, and the divalent iron Fe 2+ Oxidized to ferric iron Fe 3 , after oxidation, it will promote the breakage of Li-O bonds, causing Li to move from LiFePO 4 The structure is released and the Fe-O bond is slightly affected, thereby further improving the chlorination efficiency of Li, while the chlorination efficiency of Fe is not affected.

[0067] Comparative Example 2 is to use only NH 4 ClH 2 O-NH 4 In the mechanical chlorination system, the leaching efficiency of Li is 35.01% and that of Fe is 0.26, which indicates that the leaching efficiency of NH 4 Cl and H 2 O 2 Only synergistic effect can form H 2 O 2 -NH 4 Only in the Cl mechanical chlorination system can Li achieve the best chlorination efficiency.

[0068] Table 1. Chlorination / leaching effects of metallic lithium and iron in Examples 1 to 3 and Comparative Examples 1 to 3 (II) NH 4 Cl+H 2 O 2 Experiment on the mechanism of synergistically enhanced LFP mechanical chlorination The breaking of Li-O bonds in the mechanochemical process of LFP has always been a problem. Under natural ball milling conditions, only a small number of Li-O bonds will break, which is far from meeting the needs of Li chlorination and resource conversion. 4 The role of Cl is to provide Cl for metal Li to bind - ions and H produced by partial hydrolysis + The ions make the solution slightly acidic, H 2 O 2 Under weakly acidic conditions, its oxidation performance is greatly improved, and the divalent iron Fe 2+ Oxidized to ferric iron Fe 3 , after oxidation, it will promote the breakage of Li-O bonds, causing Li to move from LiFePO 4 The structure is released and the Fe-O bond is slightly affected.

[0069] The inventors also found in the experiment that H 2 O2 The free radicals generated may be in LiFePO 4 It plays an important role in the breaking of bonds, thereby enhancing the mechanical chlorination efficiency. The reaction is as follows: Fe 2+ +H 2 O 2 →Fe 3+ +OH - +·OH(2) H 2 O 2 →2H 2 O+O 2 (3) Fe 2+ +·OH→Fe 3+ +OH-(4) OH+H 2 O 2 →2H 2 O+HO 2 (5) Fe 3+ + HO 2 →Fe 2+ + H + + O 2 (6) Fe 2+ +HO 2 +H + →Fe 3+ +H 2 O 2 (7) HO 2 →O 2 - +H + (8) HO 2 ·+·OH→H 2 O+ 1 O 2 (9) Fe 2+ +O 2 →Fe 3+ +O 2 - ·(10) 2Fe 2+ +H 2 O 2 →2Fe 3+ +2OH - (11) H 2 O 2 → OH → HO 2 →O2 - → 1 O 2 (12) However, the strong reactivity of these radicals means that they have a short lifetime and are difficult to capture and quantify directly. 2 O 2 How to strengthen the formation and reaction mechanism of free radicals during the mechanical chlorination of LFP poses a challenge. That is, which free radicals can strengthen the breaking of Li-O bonds without affecting the breaking of Fe-O bonds, and which free radicals strengthen the breaking of Li-O bonds and Fe-O bonds at the same time. In this regard, the inventors thought of adding appropriate amounts of different types of quenchers: methanol (MeOH), n-butanol (NBA), tert-butanol (TBA), para-benzoquinone (BQ), and furfuryl alcohol (FFA). By comparing the chlorination efficiency of Li and Fe before and after the addition of the quencher, the existence and formation mechanism of free radicals were confirmed, and the reaction pathway of free radicals with LFP was inferred.

[0070] The chlorination efficiency of Li and Fe in Experimental Examples 1-5 under different quenching agents was measured respectively, and the results are shown in Table 2 and Figure 2 shown.

[0071] Table 2. Chlorination efficiency of Li and Fe under different quenchers Since methanol (MeOH), n-butanol (NBA) and tert-butanol (TBA) are quenchers of hydroxyl radical ·OH, and p-benzoquinone (BQ) is a quencher of hydroperoxyl radical HO 2 · And superoxide radical O 2 - · Quencher, furfuryl alcohol (FFA) is a singlet oxygen radical 1 O 2 of a quencher; Figure 3 It can be seen that: 1. When methanol (MeOH), n-butanol (NBA) and tert-butanol (TBA) are selected as quenchers, that is, when OH is quenched, it is equivalent to blocking the entire free radical chain reaction (H 2 O 2 → OH → HO 2 →O 2 - → 1 O 2), the result is that the chlorination efficiency of Li decreases to varying degrees, while the chlorination efficiency of Fe does not change significantly; this is because the quenching effect of these three alcohols is relatively poor, and due to the limitation of the tank capacity during the experiment, it is impossible to add enough quencher (adding too much liquid will spill out during the ball milling process) to prevent the chain reaction of free radicals, resulting in H 2 O 2 → OH → HO 2 →O 2 - → 1 O 2 The reaction path can still proceed, but is slightly blocked; 2. When benzoquinone (BQ) is selected as the quencher, the free radical HO 2 ·、O 2 - ·and 1 O 2 The generation of 2 →O 2 - → 1 O 2 The chlorination efficiency of Li is also reduced, while the chlorination efficiency of Fe is significantly improved due to the destruction of Fe-O bonds by the strongly oxidizing OH. (3) When furfuryl alcohol (FFA) is selected as the quencher, the free radical 1 O 2 When quenched, the efficiency of lithium is significantly reduced, which is similar when BQ is used as the quencher, and the chlorination efficiency of Fe is higher.

[0072] The above experimental results show that the three free radicals OH, HO 2 · and O 2 - · is the main reason for the breakage of Fe-O bonds, and methanol, n-butanol, and tert-butanol are quenchers of ·OH. The addition of these three alcohols will prevent the generation of ·OH and subsequent free radicals to a certain extent (H 2 O 2 → OH → HO 2 →O 2 - → 1 O 2 ); and free radicals 1 O 2 It is the main reason for the breakage of Li-O bonds and has a strong electron affinity. 1 O 2 It can polarize the Li-O bond, weaken the strength of the Li-O bond, and eventually lead to the breakage of the Li-O bond. The stability of Fe-O is due to the PO 4 3-It retains its structure and captures the surrounding Fe 3+ Formation of FePO 4 , achieving the directional enrichment of Fe and P.

[0073] (III) H 2 O 2 -NH 4 The main reaction pathways of Cl mechanical chlorination system like Figure 3 and Figure 4 As shown, samples before and after mechanical chlorination under different conditions were tested: LFP sample (a), H 2 O-NH 4 Cl mechanical chlorination system produces filter residue sample (b), H 2 O 2 -NH 4 LFP sample (c) after ball milling in Cl mechanical chlorination system and H 2 O 2 -NH 4 XRD spectrum and FT-IR spectrum of the filter residue sample (d) produced by the Cl mechanical chlorination system. Figure 3 In Example 1, H 2 O-NH 4 XRD pattern of the filter residue sample produced by Cl mechanical chlorination system ( Figure 3 b), the main phase was observed to be FePO 4 , which is consistent with the result that only a small amount of Li was chlorinated and leached. 2 O 2 -NH 4 In the Cl mechanical chlorination system, the XRD patterns of LFP samples before and after ball milling ( Figure 3 c) Display NH 4 Cl and FePO 4 As the main phase, accompanied by LiCl phase. 2 O 2 -NH 4 The main phase of the filter residue sample produced by the Cl mechanical chlorination system is FePO 4 ( Figure 3 d) XRD spectrum confirms that LiFePO 4 FePO 4 The oxidation transition of Li is shown in Figure 2, indicating that Li is deintercalated.

[0074] Figure 4 In, from Figure 4 a to Figure 4 b, the peak position does not change significantly. 469.02cm -1 and 502.05cm -1The peak at Li + The movement of Li x FePO 4 decreases with the decrease of x ( Figure 4 a and 4c). 2 O 2 -NH 4 In the LFP sample of Cl mechanical chlorination system, LiFePO 4 Medium octahedral FeO 6 At 636.56cm -1 The stretching vibration at 655.18 cm -1 LiFePO 4 The center is 969.01cm -1 PO 4 3- The symmetric stretching vibration mode band gradually shifts to 957.12 cm in FePO4 -1 , 1401.41cm -1 The peak at PO 4 3- The antisymmetric stretching of 4 Formation; 3170.36cm -1 The peak at 3403.52cm is due to the vibration of the NH bond in the excess NH4Cl. -1 The peak at may correspond to the symmetric stretching vibration of the OH bond, indicating that the sample may contain water or hydroxyl groups. 4 After Cl component, 3170.36cm -1 The corresponding peak disappears, and the positions of other peaks do not change significantly.

[0075] In order to further confirm the main reaction path in the mechanical chlorination process, the H 2 O 2 -NH 4 In the Cl mechanical chlorination system, XPS analysis was performed on the samples before and after mechanical ball milling. Figure 5 As shown in the Li 1s spectrum, it can be seen that the characteristic peak of Li shifted after mechanical chlorination, and the characteristic peak of Li 1s moved from high binding energy (56.20 eV) to low binding energy (56.10 eV), indicating that LiFePO 4The deintercalation of Li. After the reaction, the main peaks of Fe 2p3 / 2 and Fe 2p1 / 2 in the LFP cathode material shifted from 711.61 eV to 712.58 eV and from 724.54 eV to 726.53 eV, respectively, showing an obvious shift towards higher binding energy. This indicates that Fe(II) in LFP was oxidized to Fe(III) during the mechanical chlorination process. However, it can be seen from the P 2p spectrum that there was almost no change in the peak position and the position in front of the peak, indicating that its structure was highly similar to that before mechanical chlorination. Further confirmed LiFePO 4 to FePO 4 The transformation is accompanied by the deintercalation of Li.

[0076] (IV) Realize the high value-added and nearly full recovery of products through the coupling of chlorination and fluorination 1. LiF conversion and NH 4 Cl regeneration mechanism First, NH 2 O 2 ammonium chloride NH 4 Cl was selected to be added during the intensified ball milling process to provide Cl - ions for metallic Li, that is, LiCl was generated by the chlorination reaction, and then ammonium fluoride NH 4 F was selected as the precipitant for Li, and LiCl was converted into the high-value product LiF. During the coupling of chlorination and fluorination reaction, NH 4 F and LiCl are soluble in water and dissociate into NH 4 + , F - and Li + , Cl - (Equations 13 and 14). When the two substances are mixed in water, a double decomposition reaction will occur, and NH 4 + combines with Cl - to form NH 4 Cl, and Li + combines with F - to form LiF (Equations 15 and 16). The reaction process is as follows: LiCl → Li + + Cl - (13) NH 4 F → NH 4 + + F - (14) Li + + F - → LiF (15) NH 4 + + Cl -→NH 4 Cl (16) As Figure 6 shown, from the perspective of lattice energy analysis, the strong attractive interaction between Li with a small ionic radius and F with a large charge density is the main reason for the high lattice energy of LiF. From the perspective of Gibbs free energy analysis (see + a), the formation process of LiF precipitation reduces the number of ions in the solution, resulting in a decrease in the entropy of the system. The energy released during the process compensates for the heat absorbed during the dissolution process, promoting the forward reaction. In terms of solubility differences, LiCl, NH - F and NH Figure 6 F are easily soluble in water, and the solubility of LiF is significantly lower than that of the other three salts, resulting in its preferential precipitation and promoting the forward reaction. 4 F and NH 4 Cl are easily soluble in water, and the solubility of LiF is significantly lower than that of the other three salts, resulting in its preferential precipitation and promoting the forward reaction.

[0077] H 2 O 2 Enhanced mechanical chlorination coupled with fluorination reaction for treating waste LiFePO 4 The reaction mechanism for preparing high-value LiF is as Figure 7 shown. Under the action of mechanical force, the 2 O 2 generated by H 1 O 2 can selectively break the Li-O bond with low bond energy in LiFePO 4 and release Li + which combines with Cl - to form LiCl. Similar to the charging process of LFP batteries, LiFePO 4 is oxidized to FePO 4 , and the crystal structure remains unchanged. The conversion of LiCl to LiF is due to the combination of Li with a small ionic radius and F with a large charge density after adding NH 4 F. In addition, the formation of low-solubility LiF precipitation will increase the entropy of the system, thus promoting the forward progress of the metathesis reaction. During the defluorination process, the aluminum-loaded functional groups in the regenerated resin show strong selective adsorption for F + and release an equal amount of Cl - which combines with NH - to form NH - Cl during the ion exchange process. 4 + to form NH 4 Cl.

[0078] 2. High-value utilization of LiF products and recycling of NH 4 Cl and defluorination resin The fluorination reaction, i.e., the conversion process of LiF, produces NH 4 Cl, and the F in the residual liquid of LiF conversion- is removed by defluorination resin. During the ion exchange process, the functional groups on the resin will release an equal amount of Cl - , F - is adsorbed on the resin to remove F in the residual liquid of LiF conversion - . When the defluorination resin reaches saturation, aluminum AlCl 3 solution is used for regeneration to restore its performance. Al 3+ in the regeneration solution will desorb F - in the resin to form an Al-F complex, thus realizing the regeneration and recycling of the resin.

[0079] At the same time, the main solute of the LiF conversion solution is converted into NH 4 Cl, and this part of NH 4 Cl and the remaining NH 4 Cl from the chlorination reaction, as well as the derived NH 4 Cl during the defluorination process, are all recovered and reused, thus greatly reducing the consumption of materials and lowering the cost. The XRD pattern shows that the recycled NH 4 Cl has good crystallization (see Figure 6 c).

[0080] On the other hand, most of the lithium-ion battery recycling processes in the prior art choose carbonate or phosphate to obtain the products Li 2 CO 3 or Li 2 PO 4 , and the solubility of Li 2 CO 3 and Li 2 PO 4 is much higher than that of LiF, which leads to the waste of recycled Li. To verify the solubility difference, the lithium concentrations in saturated Li 2 CO 3 solution and saturated LiF solution were tested under the same conditions: At room temperature, the solubility of Li 2 CO 3 is 1.33 grams, and the calculation process of the Li 2 CO 3 concentration in the saturated Li + solution is as follows: Moles·of Li + =2×Moles of Li 2 CO 3 =2×0.0180mol=0.0360mol At room temperature, the solubility of LiF is 0.13 grams. In a saturated LiF solution, the Li + concentration is calculated as follows: Moles of·Li + = Moles of LF = 0.00501 mol Therefore, in the saturated Li 2 CO 3 solution, the Li + concentration is much higher than that in the saturated LiF solution. This indicates that under the same conditions, the efficiency of recovering Li in the form of LiF is much higher than that of the existing technology for recovering the product Li 2 CO 3 .

[0081] In addition, compared with Li 2 CO 3 , LiF has a higher value. LiF is widely used in processes such as fluxes, glazes, dosimetry, brazing, and aluminum casting. More importantly, LiF plays a key role in the field of solid-state batteries by improving the interface, increasing ionic conductivity, and enhancing electrochemical stability. Figure 6 The XRD pattern of b shows that LiF is well-crystallized.

[0082] The price of per ton of battery-grade Li 2 CO 3 is 76,350 yuan, while the price of per ton of battery-grade LiF is 143,500 yuan (https: / / new-energy.smm.cn / , accessed in January 2025).

[0083] Taking 1 ton of product as an example: LiF has high purity, high yield, simple process, low production cost, and high added value, showing good economic benefits. However, the recovery process of Li 2 CO 3 is complex, has high energy consumption, relatively low purity and recovery rate, resulting in high production cost and relatively poor economic benefits, making it difficult to industrialize.

[0084] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for recovering high-value waste lithium iron phosphate battery positive electrode materials, characterized in that: The following steps are involved: Step A, pre-treating the waste lithium iron phosphate battery to obtain a lithium iron phosphate positive electrode material; Step B, adding lithium iron phosphate positive electrode material, ammonium chloride and hydrogen peroxide into a ball mill for grinding, controlling the mass ratio of ammonium chloride to lithium iron phosphate positive electrode material to be 5:2-7:2, and the volume mass ratio of hydrogen peroxide to lithium iron phosphate positive electrode material to be (18-22): 1 mL / g; Step C, after grinding, the mixture is washed out of the ball mill with deionized water, and then subjected to water leaching to fully leach the metallic lithium; after the water leaching, the mixture is filtered to obtain a filtrate containing lithium chloride and a filter residue containing iron phosphate; the filter residue is washed, dried and ground, and used in a characterization experiment, and the filtrate is homogenized to determine the chlorination efficiency of metallic lithium and iron; Step D, adding an excess of ammonium fluoride to the filtrate of step C, reacting for a period of time, filtering to obtain a reaction solution and a precipitate, and washing, drying and grinding the precipitate to obtain a product of lithium fluoride; Step E, adjusting the pH of the reaction solution of step D to 5.0-6.5, then using a defluorination resin to perform a cyclic adsorption treatment on the reaction solution, and collecting the effluent; when the adsorption of the defluorination resin reaches saturation, using an aluminum chloride solution to elute and regenerate the defluorination resin, and collecting the eluate; combining the collected effluent and the eluate, and obtaining an ammonium chloride solution after concentration treatment.

2. The method for recovering high-value waste lithium iron phosphate battery positive electrode materials according to claim 1, characterized in that: In step B, the ball-to-material ratio is (14-16):1, the grinding time is 11-13h, and the ball mill speed is 550-650 rpm.

3. The method for recovering high-value waste lithium iron phosphate battery positive electrode materials according to claim 1, characterized in that: In step C, the leaching temperature is 55-65 degrees, and the leaching time is 60-100 minutes.

4. The method for recovering high-value waste lithium iron phosphate battery positive electrode materials according to claim 1, characterized in that: In step E, the fluorine-removing resin is purchased from Xi'an Lanxiao Technology New Materials Co., Ltd., model LX-760.

5. The method for recovering high-value waste lithium iron phosphate battery positive electrode materials according to claim 1, characterized in that: In step E, the defluorination resin is eluted and regenerated using a 10% aluminum chloride solution at a flow rate of 1 BV / h, and the regeneration processing volume is 2-3 BV.

6. The method for recovering high-value waste lithium iron phosphate battery positive electrode materials according to claim 1, characterized in that: In step A, the pretreatment step is: discharging and disassembling the waste lithium iron phosphate battery to separate the positive electrode sheet, and then pyrolyzing the positive electrode sheet to separate the positive electrode material and the aluminum foil to obtain the lithium iron phosphate positive electrode material.

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