A method for recycling retired lithium-ion battery cathode materials using lithium iron phosphate-mediated solvent regeneration.

Abstract

This invention discloses a method for recycling retired lithium-ion battery cathode materials using lithium iron phosphate-mediated solvent regeneration. The method includes the following steps: leaching the retired battery cathode material with an acidic potassium bromide solution to obtain leachate A; leaching the lithium iron phosphate material with leachate A to obtain leachate B; and recycling the aforementioned steps under acidic conditions using leachate B instead of the acidic potassium bromide solution to obtain a recycled leachate enrichment solution. Due to proton attack and redox reactions with the acidic KBr solution, the cathode material undergoes structural collapse, dissociating its basic structure and leading to the dissolution of lithium and transition metals. Simultaneously, KBr is oxidized to liquid bromine. The generated acidic liquid bromine, with a higher redox potential, further selectively leaches lithium from the lithium iron phosphate through oxidation, achieving the recycling of the KBr solution. This method is simple to operate, green, and recyclable, offering significant economic and environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of battery material recycling technology, specifically relating to a method for recycling cathode materials of retired lithium batteries through lithium iron phosphate-mediated solvent regeneration. Background Technology

[0002] Achieving efficient and green recycling of retired lithium-ion power batteries is of great significance for alleviating environmental protection pressures and ensuring the sustainable development of batteries in the future. The main recycling methods for the cathode of retired lithium-ion batteries include pyrometallurgy, hydrometallurgy, and biometallurgy. Relatively speaking, hydrometallurgy has advantages such as low energy consumption, high efficiency, and low pollution, making it the primary method for recycling the cathode of retired lithium-ion power batteries.

[0003] Hydrometallurgy typically involves leaching and separation. The leaching agents used in the leaching process are mainly inorganic and organic acids. To improve the reaction rate and leaching efficiency, some redox reagents such as persulfate, hydrogen peroxide, and sodium sulfite are employed. Related technologies use oxalic acid to selectively leach lithium, obtaining solid cobalt oxalate. The cobalt oxalate is then calcined to generate cobalt oxide, completing the recovery process of the lithium cobalt oxide cathode. However, current cathode material recovery methods suffer from the problem of large amounts of leaching agents used and the inability to recycle them, which to some extent affects the recycling and utilization of cathode materials. Summary of the Invention

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a method for recycling retired lithium-ion battery cathode materials through lithium iron phosphate-mediated solvent regeneration, which can recycle the leaching solvent and has promising application prospects.

[0005] In a first aspect, the present invention provides a method for recycling retired lithium-ion battery cathode materials through lithium iron phosphate-mediated solvent regeneration, comprising the following steps:

[0006] S1, using acidic potassium bromide solution to leach the cathode material of retired lithium batteries to obtain leachate A;

[0007] S2, using leachate A to leach lithium iron phosphate material to obtain leachate B;

[0008] S3, under acidic conditions, leachate B is used instead of the acidic potassium bromide solution in the recycling steps S1 to S2 to obtain a circulating leachate enrichment solution;

[0009] The cathode material of the retired lithium battery includes at least one element selected from Ni, Co, and Mn.

[0010] The basic principle of this invention is as follows:

[0011] In this invention, based on the proton attack and redox interaction between acidic KBr solution and some cathode materials, the structure of these retired battery cathode materials can collapse, dissociating their basic structure and leading to the dissolution of lithium and transition metals such as Ni, Co, and Mn. Simultaneously, KBr is oxidized to liquid bromine. The resulting acidic liquid bromine, with a higher redox potential, can further selectively leach lithium from lithium iron phosphate through oxidation, while the lithium iron phosphate is converted to iron phosphate, and the liquid bromine is reduced back to KBr. Based on this, to achieve the recycling of the KBr solution, in step S3, the leachate B is reused as a leaching agent for the leaching of metal elements from retired lithium battery cathode materials.

[0012] This invention provides a highly efficient leaching process and method for recovering transition metals and lithium from retired lithium-ion power batteries, while also enabling the green recycling of the leaching agent. This method is simple to operate, economical, efficient, widely applicable, and green and recyclable, offering significant economic and environmental benefits and facilitating the synergistic recycling and large-scale application of resources.

[0013] In step S3, when leachate B is used instead of acidic potassium bromide solution in the cycling steps S1-S2, the retired lithium battery cathode material targeted by the leaching treatment is typically the retired lithium battery cathode material that has undergone acidic potassium bromide leaching treatment in S1, and the lithium iron phosphate material targeted by the leaching treatment is typically the lithium iron phosphate material that has undergone leaching treatment with leachate A in S2. However, it is understood that in some other embodiments, it may also be the retired lithium battery cathode material that has not undergone acidic potassium bromide leaching treatment in S1, and / or, it may also be the lithium iron phosphate material that has not undergone leaching treatment with leachate A in S2.

[0014] In some embodiments of the present invention, in step S1, the mass ratio of the acidic potassium bromide solution to the retired battery cathode material is (3-100):1, and can be optionally (5-50):1.

[0015] In some embodiments of the present invention, in step S1, the concentration of potassium bromide in the acidic potassium bromide solution is 0.2-8 mol / L, and may be 0.5-4 mol / L.

[0016] In some embodiments of the present invention, in step S1, the acidic potassium bromide solution includes an inorganic acid. Optionally, the inorganic acid includes at least one of hydrochloric acid or sulfuric acid.

[0017] In some embodiments of the present invention, in step S1, the concentration of inorganic acid in the acidic potassium bromide solution includes 0.1-5 mol / L, and may be selected as 0.2-1.6 mol / L.

[0018] In some embodiments of the present invention, in step S1, the cathode material of the retired battery includes lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), and lithium nickel cobalt oxide (LiNi). x Co 1-x O2), lithium nickel manganese oxide (LiNi) x Mn 1-x O2), lithium nickel cobalt manganese oxide (LiNi) x Co y Mn 1-x-y O4) and lithium nickel manganese aluminum oxide (LiNi x Co y Al 1-x-y At least one of O4), x, y, 1-x, and 1-xy are all positive numbers.

[0019] In some embodiments of the present invention, the lithium nickel cobalt manganese oxide includes, but is not limited to, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 At least one of O2, etc.

[0020] In some embodiments of the present invention, in step S1, the leaching temperature is 40-150°C, and can be selected as 60-100°C.

[0021] In some embodiments of the present invention, in step S1, the leaching time is 0.2-10h, and can be selected as 1-4h.

[0022] In some embodiments of the present invention, in step S1, an acidic potassium bromide solution and powder of retired lithium battery cathode material are mixed, subjected to a leaching reaction, and filtered to obtain leaching solution A.

[0023] In some embodiments of the present invention, in step S1, an acidic potassium bromide solution and a retired battery positive electrode material powder are mixed and stirred to carry out a leaching reaction, wherein the stirring rate includes 50-3000 rpm, such as 100-1000 rpm.

[0024] In some embodiments of the present invention, in step S2, the lithium iron phosphate material includes the cathode material of a retired lithium iron phosphate battery.

[0025] In some embodiments of the present invention, in step S2, the leaching temperature is 40-150°C, and can be selected as 70-100°C.

[0026] In some embodiments of the present invention, in step S2, the leaching time is 0.2-12h, and can be selected as 0.5-6h.

[0027] In some embodiments of the present invention, in step S2, the mass ratio of the leachate A to the lithium iron phosphate material is (5-200):1, or optionally (10-100):1.

[0028] In some embodiments of the present invention, in step S2, leachate A and lithium iron phosphate material are mixed, stirred and leached, and filtered to obtain leachate B.

[0029] In some embodiments of the present invention, in step S2, the stirring rate is 50-3000 rpm, such as 100-1000 rpm.

[0030] In some embodiments of the present invention, the leaching temperature and time in step S3 may be the same as or different from the leaching temperature and time in steps S1 and S2. Optionally, in step S3: the leaching temperature for the retired lithium battery cathode material and the lithium iron phosphate are independently 40-150°C, optionally 60-100°C; the leaching time for the retired lithium battery cathode material and the lithium iron phosphate are independently 0.2-10h, optionally 1-4h; the stirring rate in the leaching treatment of the retired lithium battery cathode material and the lithium iron phosphate is independently 50-3000rpm, such as 100-1000rpm.

[0031] In some embodiments of the present invention, in step S3, the mass ratio of leachate B to retired lithium battery cathode material is (3-60):1, and can be selected as (5-50):1.

[0032] In some embodiments of the present invention, in step S3, under acidic conditions, leachate B is used instead of acidic potassium bromide solution to cycle steps S1 to S2 a total of n times, where n is a positive integer.

[0033] In some embodiments of the present invention, 20 ≥ n > 0, and optionally, 9 ≥ n ≥ 1.

[0034] In some embodiments of the present invention, the recovery method further includes step S4: a step of removing iron from the circulating leaching enrichment solution, specifically including: adjusting the pH of the circulating leaching enrichment solution, adding hydrogen peroxide, reacting, filtering, and obtaining a purified solution.

[0035] In some embodiments of the present invention, in step S4, the pH of the circulating leachate enrichment solution is adjusted to 2.5-6.

[0036] In some embodiments of the present invention, in step S4, the temperature of the reaction is 20-95°C, and optionally 25-80°C.

[0037] In some embodiments of the present invention, in step S4, the reaction time is 0.5-36 h, optionally 0.5-12 h.

[0038] In some embodiments of the present invention, in step S4, the amount of hydrogen peroxide added is 1-10% by volume concentration.

[0039] In some embodiments of the present invention, the recovery method further includes step S5: adjusting the purified liquid to alkaline, reacting, filtering, and obtaining a transition metal precursor and a lithium-rich filtrate.

[0040] In some embodiments of the present invention, in step S5, the pH of the purified solution is adjusted to 7.1-14, and the reaction is carried out.

[0041] In some embodiments of the present invention, in step S5, the temperature of the reaction is 25-80°C.

[0042] In some embodiments of the present invention, in step S5, the reaction time is 10-360 min.

[0043] Through the above implementation method, the purification liquid is adjusted to alkaline, a precipitation separation reaction is carried out, the precipitation separation time is 10-360 minutes, and then the solid and liquid are separated by filtration.

[0044] In some embodiments of the present invention, in step S5, the solid obtained after filtration is washed with water and dried to obtain the transition metal precursor. Optionally, the number of water washings is 3-5 times. Optionally, the drying temperature is 80-120°C and the drying time is 6-12 hours.

[0045] In some embodiments of the present invention, the recovery method further includes step S6: mixing the lithium-rich filtrate with sodium carbonate, reacting, filtering, and obtaining lithium carbonate.

[0046] Through the above-described embodiments, lithium in the lithium-containing filtrate is precipitated using the sodium carbonate precipitation method to obtain lithium carbonate.

[0047] In some embodiments of the present invention, in step S6, the reaction temperature is 75-110°C, and optionally 90-100°C.

[0048] In some embodiments of the present invention, in step S6, the reaction time is 0.5-12h, or optionally 0.5-6h.

[0049] In some embodiments of the present invention, in step S6, the lithium-rich filtrate is mixed with a saturated sodium carbonate solution.

[0050] In some embodiments of the present invention, in step S6, the filtered solid is washed and dried to obtain lithium carbonate. Optionally, the solid is washed 3-5 times with water at 90-100°C and then dried at 60-100°C for 6-24 hours to obtain lithium carbonate.

[0051] In some embodiments of the present invention, the recycling method further includes step S0: discharging the retired lithium battery, disassembling it, and obtaining the positive electrode material and current collector of the retired lithium battery. Optionally, the current collector includes, but is not limited to, aluminum foil.

[0052] In a second aspect, the present invention proposes the application of the above-mentioned method for recycling the cathode material of retired batteries in the recycling of materials from retired batteries.

[0053] The beneficial effects of this invention include:

[0054] (1) This invention is based on the redox reaction process between acidic potassium bromide and the positive electrode material (such as lithium cobalt oxide, lithium manganese oxide and lithium nickel cobalt manganese oxide, etc.) for leaching. The leaching efficiency of lithium and transition metals nickel, cobalt and manganese can reach more than 98%. It has the advantages of high leaching efficiency, simple operation and good universality, and has good application prospects.

[0055] (2) The reduction and regeneration of potassium bromide leaching agent mediated by retired lithium iron phosphate cathode material enables the leaching solvent in the recovery process of this invention to be green and recyclable, with low acid / alkali consumption and reagent consumption, and has good economic and environmental benefits.

[0056] (3) Based on the concept of synergistic utilization of the cathodes of various retired lithium-ion power batteries, this invention adopts the synergistic reaction process of regenerated leachate of retired lithium iron phosphate cathode, which has a good promoting effect on the synergistic utilization of retired power batteries and can form a good technology cycle system. Attached Figure Description

[0057] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0058] Figure 1 This is a schematic diagram of the process flow for the recycling method of the positive electrode material of retired batteries in Embodiment 1 of the present invention;

[0059] Figure 2 The graph shows the test results of the leaching efficiency of potassium bromide solution on metal elements in various waste cathodes in step (II) of Examples 1 and 9-12 of the present invention.

[0060] Figure 3The figure shows the leaching efficiency test results of cobalt and lithium in waste cobalt lithium oxide waste using acidic potassium bromide solutions of different sulfuric acid concentrations in step (II) of Examples 1-2 of the present invention.

[0061] Figure 4 The graph shows the leaching efficiency test results of acidic potassium bromide solutions with different potassium bromide concentrations on cobalt and lithium in waste cobalt lithium oxide cathodes in step (II) of Examples 1 and 3 of the present invention.

[0062] Figure 5 The graph shows the test results of the leaching efficiency of cobalt in waste cathode cobalt lithium oxide under different leaching times and temperatures in step (II) of Examples 1 and 4-8 of the present invention.

[0063] Figure 6 The graph shows the test results of lithium leaching efficiency in waste cobalt lithium oxide cathode at different leaching times and temperatures in step (II) of Examples 1 and 4-8 of the present invention.

[0064] Figure 7 The graph shows the leaching efficiency test results of potassium bromide solution after 5 cycles of regeneration for cobalt and lithium in waste cobalt lithium oxide cathode in Example 1 of the present invention.

[0065] Figure 8 This is a graph showing the UV-Vis light test results of the leachate sampled at different reaction time points in the leaching treatment of waste lithium cobalt oxide cathode powder in Example 1 of the present invention.

[0066] Figure 9 The image shows the leaching results of lithium iron phosphate by potassium bromide and lithium cobalt oxide leachate in step (III) of Example 1 of the present invention. Detailed Implementation

[0067] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0068] Unless otherwise specified, the experimental methods described in the following examples are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used are all commercially available from the conventional market unless otherwise specified.

[0069] Example 1

[0070] This embodiment discloses a method for recycling cathode materials from retired batteries, and its process diagram is shown below. Figure 1 As shown, it includes the following steps:

[0071] (I) Discharge and disassemble the retired lithium cobalt oxide battery (ICR18650, Panasonic) to obtain waste lithium cobalt oxide cathode powder.

[0072] Prepare 50 mL of 0.6 mol / L sulfuric acid solution, then add potassium bromide to dissolve and form a 0.6 mol / L acidic potassium bromide solution.

[0073] (II) Leaching treatment of waste lithium cobalt oxide cathode powder, including: weighing 1g of waste lithium cobalt oxide cathode powder from step (I), adding it to the prepared potassium bromide solution, stirring and leaching at 400rpm, leaching temperature of 90℃, and leaching time of 2h. After the leaching reaction is completed, leaching solution A is obtained by filtration, with leaching rates of 99.38% for lithium and 99.12% for cobalt.

[0074] (III) Leaching treatment of lithium iron phosphate, including: placing 0.5g of lithium iron phosphate (IFR18650) in the leaching solution of lithium cobalt oxide (i.e., leaching solution A), leaching at 90℃ for 1h, stirring at 600rpm, and after the reaction is completed, filtering to obtain leaching solution B (leaching solution of lithium iron phosphate), the leaching rate of iron in lithium iron phosphate is 42.57%, and the leaching rate of lithium is 98.74%.

[0075] (IV) Five cycles of leachate recycling, including: adjusting the acidity of the lithium iron phosphate leachate to the solution acidity under the first lithium cobalt oxide leaching reaction conditions, replacing the potassium bromide solution to leach waste lithium cobalt oxide cathode powder (other reaction conditions are the same as in step (II)), obtaining lithium cobalt oxide leachate, and then using the obtained lithium cobalt oxide leachate to leach lithium iron phosphate, with specific reaction conditions the same as in step (III); continuing to recycle the leachate: using the same reaction conditions to cycle the leaching treatment of waste lithium cobalt oxide cathode powder-lithium iron phosphate leaching treatment 4 times, finally obtaining a recycled leaching enrichment solution. Figure 4 As shown, after 5 cycles, the leaching enrichment solution showed that the leaching rates of cobalt and lithium were both above 90%, achieving good recycling of the solvent.

[0076] (V) Adjust the pH of the circulating leachate to 4.5, add 5 mL of hydrogen peroxide (H2O2 mass fraction of 30%), and react at 25℃ for 3 h. The iron precipitation rate reached 99.38%, achieving a good purification effect for the circulating liquid.

[0077] (VI) The filtrate obtained by filtration is further adjusted to pH 12.5. After precipitation reaction for 2 hours, it is filtered, washed and dried to obtain the recovery product (precursor) of the transition metal.

[0078] (VII) Add 10 mL of saturated sodium carbonate solution to the filtrate in step (VI), and precipitate at 95 °C for 6 h. Filter the resulting white precipitate, wash with boiling water, and dry to obtain lithium carbonate.

[0079] In some other embodiments of the present invention, sulfuric acid may be replaced with hydrochloric acid.

[0080] Example 2

[0081] This embodiment discloses a series of methods for recycling cathode materials of retired batteries. The only difference between this embodiment and Example 1 is that the sulfuric acid concentration in the sulfuric acid solution in step (I) of this embodiment is 0.0 mol / L, 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, and 0.8 mol / L, respectively.

[0082] Example 3

[0083] This embodiment discloses a series of methods for recycling cathode materials from retired batteries. The only difference between this embodiment and Example 1 is that in the recycling methods of this embodiment, the concentration of potassium bromide in the acidic potassium bromide solution in step (I) is 0.0 mol / L, 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.35 mol / L, 0.4 mol / L, and 0.5 mol / L, respectively.

[0084] Example 4

[0085] This embodiment discloses a series of recycling methods for the positive electrode materials of retired batteries. The only difference between this embodiment and Embodiment 1 is that the leaching time in step (II) of the recycling methods in this embodiment is 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 80 min, 100 min, and 120 min, respectively.

[0086] Example 5

[0087] This embodiment discloses a series of recycling methods for the positive electrode materials of retired batteries. The only difference between this embodiment and Embodiment 4 is that the leaching temperature in step (II) of the recycling method in this embodiment is 60°C.

[0088] Example 6

[0089] This embodiment discloses a series of recycling methods for the positive electrode materials of retired batteries. The only difference between this embodiment and Embodiment 4 is that the leaching temperature in step (II) of the recycling method in this embodiment is 70°C.

[0090] Example 7

[0091] This embodiment discloses a series of recycling methods for the positive electrode materials of retired batteries. The only difference between this embodiment and Embodiment 4 is that the leaching temperature in step (II) of the recycling method in this embodiment is 80°C.

[0092] Example 8

[0093] This embodiment discloses a series of recycling methods for the positive electrode materials of retired batteries. The only difference between this embodiment and Embodiment 1 is that the leaching temperatures in step (II) of this series of recycling methods are 60°C, 70°C, and 80°C.

[0094] Example 9

[0095] This embodiment discloses a method for recycling the positive electrode material of retired batteries. The only difference between this embodiment and Embodiment 1 is that the retired waste battery used in this embodiment is an NCM622 battery.

[0096] Example 10

[0097] This embodiment discloses a method for recycling the positive electrode material of retired batteries. The only difference between this embodiment and Embodiment 1 is that the retired waste battery used in this embodiment is an NCM523 battery.

[0098] Example 11

[0099] This embodiment discloses a method for recycling the positive electrode material of retired batteries. The only difference between this embodiment and Embodiment 1 is that the retired waste battery used in this embodiment is an NCM511 battery.

[0100] Example 12

[0101] This embodiment discloses a method for recycling the positive electrode material of retired batteries. The only difference between this embodiment and Embodiment 1 is that the retired waste battery used in this embodiment is an LMO battery.

[0102] Example 13

[0103] This embodiment discloses a series of methods for recycling cathode materials of retired batteries. The only difference between this embodiment and Example 1 is that the amount of lithium iron phosphate added in this series of recycling methods is 0.05 mmol, 0.1 mmol, 0.15 mmol, 0.2 mmol, and 0.3 mmol, respectively.

[0104] Test case

[0105] This experimental example tested the leachate and elemental leaching results in the examples, specifically including:

[0106] (1) The leaching efficiency of potassium bromide solution for metal elements in various waste cathodes in step (II) of Examples 1 and 9-12 was tested. The test results are as follows: Figure 2 As shown, in Example 1, the leaching rates of lithium and cobalt in leachate A were 99.38% and 99.12%, respectively.

[0107] (2) The leaching efficiency of acidic potassium bromide solutions with different sulfuric acid concentrations in step (II) of Examples 1-2 on cobalt and lithium in waste cobalt lithium oxide cathodes was tested. The test results are as follows: Figure 3 As shown.

[0108] (3) The leaching efficiency of acidic potassium bromide solutions with different potassium bromide concentrations for cobalt and lithium in waste cobalt lithium oxide cathodes was tested in step (II) of Examples 1 and 3. The test results are as follows: Figure 4 As shown.

[0109] (4) The leaching efficiency of cobalt and lithium in waste cobalt cathode lithium oxide was tested under different leaching times and temperatures in step (II) of Examples 1 and 4-8. The test results are as follows: Figure 5-6 As shown.

[0110] (5) The leaching efficiency of the potassium bromide solution regenerated in Example 1 after 5 cycles for cobalt and lithium in the waste positive electrode cobalt lithium oxide was tested. The test results are as follows: Figure 7 As shown.

[0111] (6) The leachate samples taken at different reaction time points in step (II) of Example 1 and the leachate samples taken at different reaction time points during the leaching process of the waste lithium cobalt oxide cathode powder in the 5th cycle were subjected to ultraviolet-visible light testing. The test results are as follows: Figure 8 As shown: Test results of leachate samples taken at different reaction time points in step (II). Figure 8 As shown in Figure a, the test results of the leachate sampled at different reaction time points during the leaching process of waste lithium cobalt oxide cathode powder in the 5th cycle treatment. Figure 8 As shown in b.

[0112] (7) The leaching results of lithium iron phosphate by potassium bromide and lithium cobalt oxide leachate in step (III) of Example 1 were tested. The test results are as follows: Figure 9 As shown.

[0113] In summary, this invention discloses a closed-loop process for recovering multiple valuable metals from retired lithium-ion power batteries based on a synergistic regeneration mechanism of retired lithium iron phosphate and potassium bromide solvent. This process uses an acidic potassium bromide solution as the leaching agent to leach lithium and transition metals from the cathode materials of spent lithium-ion batteries, such as ternary or lithium manganese oxide. Then, the potassium bromide solution is regenerated through the reaction of lithium iron phosphate with the leaching solution, simultaneously achieving selective leaching of lithium from the retired lithium iron phosphate cathode. Finally, transition metals and lithium are separated by precipitation to generate transition metal precursors and lithium salts, respectively. Specifically, the acidic potassium bromide solution can react with spent cathodes containing nickel / cobalt / manganese through a redox reaction, causing the leaching of metal ions, Br... - It is then oxidized to liquid bromine; the generated liquid bromine has a higher redox potential than lithium iron phosphate in acidic media, thus it can oxidize lithium iron phosphate to iron phosphate and cause lithium to dissolve; at the same time, the liquid bromine is reduced again to Br. - It can be used in the re-leaching process of the positive electrode.

[0114] The recycling method in this invention is simple to operate, economical and efficient, widely applicable and green and recyclable, with good economic and environmental benefits, and is conducive to the coordinated recycling and utilization of resources and large-scale promotion and application.

[0115] It should be noted that, unless otherwise specified, "room temperature" or "normal temperature" in this article refers to approximately 25°C; and the word "approximately" in numerical values ​​in this article means an error of ±2%.

[0116] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A method for recycling retired lithium battery cathode materials through lithium iron phosphate-mediated solvent regeneration, characterized in that, Includes the following steps: S1, using acidic potassium bromide solution to leach the cathode material of retired lithium batteries to obtain leachate A; S2, using leachate A to leach lithium iron phosphate material to obtain leachate B; S3, under acidic conditions, leachate B is used instead of the acidic potassium bromide solution in the recycling steps S1~S2 to obtain a circulating leachate enrichment solution; The cathode material of the retired lithium battery includes at least one element selected from Ni, Co, and Mn.

2. The method for recycling the cathode material of retired lithium batteries according to claim 1, characterized in that, The mass ratio of the acidic potassium bromide solution to the retired lithium battery cathode material is (3-100):1, and the concentration of potassium bromide in the acidic potassium bromide solution is 0.2-8 mol / L.

3. The method for recycling the cathode material of retired lithium batteries according to claim 1, characterized in that, The cathode material of the retired lithium battery includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide.

4. The method for recycling the positive electrode material of retired lithium batteries according to claim 1, characterized in that, In step S1, the leaching temperature is 40-150℃; and / or the leaching time is 0.2-10 h.

5. The method for recycling the positive electrode material of retired lithium batteries according to claim 1, characterized in that, In step S2, the leaching temperature is 40-150℃; and / or the leaching time is 0.2-12 h.

6. The method for recycling the positive electrode material of retired lithium batteries according to claim 1, characterized in that, In step S2, the mass ratio of the leachate A to the lithium iron phosphate material is (5-200):1; and / or, the lithium iron phosphate material includes the cathode material of a retired lithium iron phosphate battery.

7. The method for recycling the positive electrode material of retired lithium batteries according to claim 1, characterized in that, In step S3, under acidic conditions, leachate B is used instead of the acidic potassium bromide solution to cycle steps S1 to S2 a total of n times, where n is a positive integer.

8. The method for recycling the positive electrode material of retired lithium batteries according to claim 7, characterized in that, 20≥n>0。 9. The method for recycling the positive electrode material of retired lithium batteries according to claim 1, characterized in that, The recovery method further includes step S4: the iron removal step in the circulating leaching enrichment solution, specifically including: adjusting the pH of the circulating leaching enrichment solution to 2.5-6, adding hydrogen peroxide, reacting at 20-95℃ for 0.5-36 h to obtain a purified solution.

10. The method for recycling the cathode material of retired lithium batteries according to claim 9, characterized in that, The recovery method further includes step S5: adjusting the purified liquid to alkaline, reacting at 25-80℃ for 10-360 min, filtering, and obtaining transition metal precursors and lithium-rich filtrate.

11. The method for recycling the cathode material of retired lithium batteries according to claim 10, characterized in that, The pH of the purified solution was adjusted to 7.1-14, and the reaction was carried out.

12. The method for recycling the positive electrode material of retired lithium batteries according to claim 10, characterized in that, The recovery method further includes step S6: mixing the lithium-rich filtrate with sodium carbonate, reacting at 75-110℃ for 0.5-12 h, filtering, and obtaining lithium carbonate.

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