Recycling method and application of waste lithium battery

Abstract

The invention provides a recycling method and application of a waste lithium battery, and relates to the technical field of lithium ion batteries. The method specifically comprises the following working procedures which are carried out in sequence: disassembly, ultrasonic cleaning, pressurized reduction leaching, neutralization, controlled potential oxidation, segmented extraction and reverse extraction and ion exchange resin treatment. According to the method, the conventional pretreatment and hydrometallurgy of the waste lithium battery are integrally improved, and manganese, nickel, cobalt and lithium elements in the battery can be effectively recycled; and meanwhile, the method has the time and cost advantages of high leaching efficiency, low reducing agent dosage, low separation and purification cost, low sewage output and the like, the obtained product and byproduct can be applied to various industries, and the method has huge popularization value and environmental protection characteristic.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to a method and application of recycling waste lithium batteries. Background Art

[0002] With the rapid popularization of electric vehicles, consumers and automobile manufacturers are paying more and more attention to battery safety issues. Power batteries are not only the main power source and core components of electric vehicles, but also the main technical barrier to their rapid development. Lithium-ion batteries are widely used in many fields such as mobile phones, electric vehicles, and mobile power supplies due to their high energy density, high cycle life, and high environmental protection. However, with the large-scale promotion of lithium batteries, the energy decay caused by "lithium embedding" in long-term use has gradually led to the scrapping of batteries, and the treatment of scrapped batteries also faces great challenges. Although lithium-ion batteries are known as "clean energy", a large amount of toxic and harmful substances such as wastewater, waste residue, and waste gas will be generated during their production process, and their treatment is a big problem. In addition, waste batteries will also generate a large amount of "industrial waste" in material recycling and cause great pollution to the environment. According to relevant reports, the amount of lithium-ion batteries to be processed in my country will reach 750,000 tons in 2022. This number will increase exponentially with the growth of time. The rational utilization of waste lithium-ion batteries is urgent.

[0003] Regarding the recycling and application of waste lithium-ion batteries, the current mainstream is cascade utilization, and the research hotspots are mainly concentrated in the three major directions of electrode material analysis and dissociation, metal hydrometallurgical enrichment, and extraction technology, and resource recycling. Specifically, the resource recycling and utilization process of waste lithium-ion batteries is mainly divided into pretreatment (discharging, disassembly, crushing, and sorting to initially separate electrode materials) and metallurgical recovery (hydrometallurgical and pyrometallurgical methods to improve the grade of valuable metals).

[0004] For the pretreatment process, the efficient removal of organic binders is the key to achieving efficient resource utilization of waste lithium-ion batteries. The efficient removal of organic binders can significantly improve the stripping efficiency of electrode materials on the surface of metal current collectors, the recovery efficiency of electrode active materials, and the regeneration and repair efficiency of electrode materials. In addition to the above-mentioned organic binders, the disassembly efficiency of batteries achieved by pretreatment greatly affects the recovery efficiency of waste battery materials. It is also worth noting that the existing decomposition technology inevitably introduces interference factors, resulting in misleading and interference in the analysis of the true cause of battery scrapping, and the relevant analysis methods for waste batteries are unscientific and imprecise; this is because in the existing disassembly process, the physical and chemical forms of waste lithium-ion batteries undergo drastic changes, resulting in the limitations of the analysis method such as complex process, insufficient detection capability, and low accuracy, and the wrong analysis results often lead to various problems in the subsequent battery recycling process, thereby wasting a lot of manpower and time costs and equipment investment.

[0005] The acid-base leaching used in traditional hydrometallurgical recycling is simple and efficient, but the secondary pollution it causes cannot be ignored, and a large amount of cost is required to deal with the pollution; therefore, processes such as low eutectic solvents, ionic liquids and supercritical fluids are used to greenly recycle positive electrode materials from waste lithium-ion batteries. In addition, compared with the traditional pyrometallurgical recycling process, the direct regeneration and repair method of waste lithium-ion battery positive electrode materials takes the restoration of positive electrode material performance in a non-destructive manner as its starting point, and has great advantages in terms of recycling efficiency, cost reduction, pollution control, etc., but it is still some distance away from industrial application.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The first purpose of the present invention is to provide a method which is mainly used to solve the defects of the existing recycling process, such as the easy introduction of impurities in the pretreatment operation and the low efficiency of removing organic binders, as well as the defects of traditional hydrometallurgical recycling, such as large amount of waste liquid, high treatment cost and difficulty in forming industrial application.

[0008] The second object of the present invention is to provide a method for processing waste lithium batteries.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0010] A method for recycling waste lithium batteries comprises the following steps:

[0011] (1) disassembling waste lithium batteries to obtain positive electrode sheets; performing ultrasonic cleaning on the positive electrode sheets to obtain a first material;

[0012] (2) immersing the first material in a sulfuric acid solution of sodium sulfite to perform a reduction pressure leaching treatment to obtain a mixed solution containing valuable metal ions; and performing an alkali neutralization treatment on the mixed solution to obtain aluminum slag and a second reaction solution;

[0013] (3) controlling the potential of the second reaction solution, oxidizing and separating the manganese in the second reaction solution, and obtaining a manganese-free third reaction solution;

[0014] (4) adding the first extractant to the third reaction liquid to separate the trace elements and obtain a fourth liquid phase;

[0015] (5) adding a second extractant to the fourth liquid phase to separate a liquid phase containing cobalt and a fifth liquid phase; extracting and purifying the liquid phase containing cobalt with sulfuric acid to obtain cobalt sulfate;

[0016] (6) adding a third extractant to the fifth liquid phase to separate a nickel-containing liquid phase and a sixth liquid phase; extracting the nickel-containing liquid phase with sulfuric acid to obtain nickel sulfate;

[0017] (7) Treating the sixth liquid phase with an ion exchange resin to obtain lithium sulfate.

[0018] A method for processing waste lithium batteries includes the waste lithium battery recycling method.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention aims at the characteristics of waste lithium battery positive electrode waste, and can significantly improve the acid leaching efficiency of positive electrode materials through the cavitation effect of ultrasonic washing. Specifically, it can effectively shorten the reaction time and reduce the reaction activation energy, reduce the temperature required for subsequent leaching, accelerate the metal leaching rate, and improve the metal leaching rate, thereby greatly saving energy and time costs.

[0021] (2) The metallurgical recovery process adopted by the present invention, through pressurized enhanced selective reduction leaching, allows valuable metals such as nickel, cobalt, and lithium in the waste battery raw materials to be dissolved into the leachate to the greatest extent, while suppressing manganese oxidation in the slag, effectively improving the utilization rate and recovery rate of valuable resources such as nickel, cobalt, lithium, and manganese in the raw materials.

[0022] (3) The present invention uses a controlled potential oxidation method to separate manganese ions in the leachate, which reduces the load and operating cost of the subsequent extraction system. At the same time, the high-grade manganese oxide slag produced can be sold, realizing the tiered high-value recovery and utilization of manganese.

[0023] (4) The present invention adopts three extractions and optimizes the reagents used in each extraction, thereby realizing green, low-energy, saponification-free extraction and separation of trace Fe and Mn impurity elements in the leaching solution, solving the problem of NH3-N wastewater generated by the traditional saponification system causing harm to the environment; further, nickel and cobalt are extracted and separated by using a non-ferrous metal separation extractant with excellent performance, and the obtained nickel sulfate is used to produce electro-nickel, and the cobalt sulfate is used to produce refined cobalt sulfate products, thereby realizing the tiered high-value recovery and utilization of nickel and cobalt.

[0024] (5) The present invention adopts an ion exchange method to adsorb and separate lithium ions in the leachate, and the lithium sulfate in the desorbed liquid can be used to produce lithium carbonate. The ion exchange method has low operating costs and high adsorption efficiency. The adsorbed liquid can be recycled, which reduces the treatment volume of high-sodium salt wastewater by 3 / 4 compared with the traditional process. No waste residue is generated during the production process, which is green and environmentally friendly, and realizes the green and high-value recycling of lithium. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A flow chart of the method of the present invention is provided;

[0027] Figure 2 A physical diagram of the test results of the test example (1) of the present invention is provided; wherein, Figure 2 (a) Figure 2 (b) Figure 2 (c) The processing results of methods (a), (b), and (c) in the test examples respectively;

[0028] Figure 3 The metallographic electron microscope image of the test example (3) of the present invention is provided; wherein, Figure 3 (a) Figure 3 (b) The leaching resin before and after immersion. DETAILED DESCRIPTION

[0029] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but those skilled in the art will appreciate that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially. In addition, the terms "first", "second" and "third" are only used for descriptive purposes and cannot be interpreted as indicating or implying relative importance.

[0030] The first aspect of the present invention is to provide a method for recycling waste lithium batteries, which mainly comprises the following steps (1) to (7) performed in sequence. Figure 1 The method flow chart of the present invention is provided. Figure 1 Explanation of the necessary and preferred embodiments of the present invention.

[0031] As a preferred embodiment, the waste lithium batteries include waste nickel-cobalt-manganese ternary lithium-ion batteries.

[0032] (1) Dismantle the waste lithium battery to obtain a positive electrode sheet; perform ultrasonic cleaning on the positive electrode sheet to obtain a first material.

[0033] As a preferred embodiment, various structural elements or components including positive electrode sheets, negative electrode sheets, diaphragms and shells can be obtained after disassembling waste lithium batteries. The present invention mainly processes the positive electrode sheets with the most complicated situation. Those skilled in the art can perform any conventional or unconventional recycling treatment on other disassembled and separated structural parts according to actual conditions.

[0034] As a preferred embodiment, the ultrasonic intensity of the ultrasonic cleaning treatment is 20kHz to 1MHz, and the duration of the ultrasonic cleaning treatment is 5min to 60min. In some optional embodiments, the ultrasonic intensity of the ultrasonic cleaning treatment includes but is not limited to any one of 20, 50, 80, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 (kHz) or a numerical interval consisting of any two thereof, and the duration of the ultrasonic cleaning treatment includes but is not limited to any one of 5, 6, 8, 10, 15, 20, 25, 30, 40, 45, 50, 55, 60 (min) or a numerical interval consisting of any two thereof.

[0035] As a preferred embodiment, stirring is continuously performed during the ultrasonic cleaning process; in some more preferred embodiments, the stirring frequency is 50rpm to 1000rpm, including but not limited to any one of 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 (rpm) or a numerical range consisting of any two of them.

[0036] As a preferred embodiment, before the ultrasonic cleaning process, acid is added to the liquid ultrasonic medium (usually water), including but not limited to oxalic acid, acetic acid or dilute sulfuric acid; in some more preferred embodiments, the acid concentration in the liquid ultrasonic medium is 0.5 mol / L to 3 mol / L.

[0037] As a preferred embodiment, before the ultrasonic cleaning process, a sulfate radical generator S2O8 is added to the liquid ultrasonic medium (usually water). 2- and catalyst Fe 2+ ; Experiments have found that when the above compounds are introduced, the efficient degradation of PVDF can be achieved during the ultrasonic-assisted stripping of the positive electrode material on the aluminum foil surface, avoiding the reaction of chemical reagents with the electrode material and the metal foil, which is beneficial to the in-situ recovery of the positive electrode material and the aluminum foil material.

[0038] Ultrasonic cavitation is when ultrasonic waves propagate in liquids, the longitudinal vibration of molecules causes the average distance between medium molecules to exceed the critical molecular distance that keeps the liquid medium unchanged, and the liquid medium breaks and forms microbubbles. After a large number of microbubbles are formed, the microbubbles expand during transmission and finally burst suddenly in a compressed state to produce a strong shock wave. The formation and rupture of microbubbles is called cavitation, which is generally considered to be the main reason for most physical and chemical effects of ultrasonic waves in solid / liquid or liquid / liquid systems.

[0039] The physical effects produced by ultrasonic cavitation include: the response of microbubbles in liquid under ultrasonic wave may be strong or mild, depending on the sound pressure and sound frequency. Ultrasonic cavitation includes transient cavitation and steady-state cavitation. Both cavitation phenomena can exist simultaneously in the medium. Under certain conditions, steady-state cavitation can be transformed into transient cavitation. Among them, transient cavitation refers to the rapid expansion of cavitation bubbles in the negative pressure phase of the sound wave under the action of large sound intensity (usually occurring within one sound wave cycle), and then being rapidly compressed to collapse under the action of the positive pressure phase of the sound wave. The power density of high-power ultrasonic wave is large, and the cavitation phenomenon is mainly transient cavitation. The huge energy released by the bubbles in the transient cavitation process will have a strong impact and peeling effect on the insoluble impurities on the surface of the object, causing the impurities to fall off in the solution. In addition, transient cavitation also has a dissolving effect on the surface components of the object, which can expose its internal components.

[0040] The chemical reactions produced by ultrasonic cavitation specifically include: sonochemical reaction, which refers to the reaction between the oxidant produced during the collapse of bubbles in the ultrasonic field and the solute. The rapid increase in the temperature inside the bubble causes water vapor and oxygen to decompose to form various oxidants, such as hydroxyl radicals (·OH), H2O2, oxygen atoms and O3, etc. The specific sources are the reactions of the following formulas (1) to (4): Since oxygen atoms easily react with water to produce H2O2 and O3 in limited quantities, the oxidant produced by ultrasonic cavitation mainly exists in the form of ·OH. In addition, the redox potential of ·OH (2.02V) is significantly higher than that of H2O2 (1.78V), and it plays a more important role in promoting electrochemical decomposition in sonochemical reactions.

[0041] H2O → ·OH + ·H (1);

[0042] H2O + ·O → 2·OH (2);

[0043] H2O + ·H → ·OH + H2 (3);

[0044] HO2 + ·H → 2·OH (4).

[0045] In summary, ultrasound can achieve the stripping of electrode materials on the surface of metal current collectors of waste lithium-ion batteries; specifically, in liquid environments including or possibly involving water, organic solvents, ionic liquids, low eutectic solvents, etc., the oxidative free radicals generated by the ultrasonic cavitation effect can promote the degradation of organic binders, thereby further improving the separation efficiency of metal current collectors and active electrode materials. The high-speed jet generated by ultrasonic cavitation is also conducive to the stripping and shedding of active electrode materials adhered to the surface of metal current collectors. Compared with conventional stirring methods, the application of ultrasonic-assisted stirring technology can significantly reduce the temperature and time required for the stripping of electrode materials and metal current collectors. Ultrasonic cavitation can also significantly improve the acid leaching efficiency of waste lithium-ion battery positive electrode materials, effectively shorten the reaction time and reduce the reaction activation energy, which can reduce the temperature required for leaching, accelerate the metal leaching rate, and increase the metal leaching rate, greatly saving energy and time costs.

[0046] As a preferred embodiment, after the ultrasonic cleaning treatment, the separated first material is dried and crushed to obtain the first material with a particle size of 150 to 300 meshes. In some more preferred embodiments, the average particle size after crushing is 200 meshes.

[0047] (2) Immersing the first material in a sulfuric acid solution of sodium sulfite for reduction pressure leaching to obtain a mixed solution containing valuable metal ions; and subjecting the mixed solution to an alkali neutralization treatment to obtain aluminum slag and a second reaction solution.

[0048] In this step, by using sodium sulfite-sulfuric acid pressure to enhance selective reduction leaching, a mixed solution containing valuable metals such as nickel, cobalt, lithium, and manganese in the discarded lithium batteries can be obtained.

[0049] As a preferred embodiment, the pressure of the pressurized leaching treatment is 0.3 MPa to 3.5 MPa. In some optional embodiments, the pressure of the pressurized leaching treatment includes but is not limited to any one of 0.3, 0.4, 0.5, 0.6, 0.8, 1, 1.5, 2, 2.5, 3, 3.5 (MPa) or a numerical range consisting of any two of them.

[0050] As a preferred embodiment, in the sulfuric acid solution of sodium sulfite, the concentration of sodium sulfite is 0.5 mol / L to 3 mol / L, and the pH of the sulfuric acid solution of sodium sulfite is 1.5 to 3.

[0051] As a preferred embodiment, the alkaline reagent for the alkali neutralization treatment includes at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide or nickel hydroxide.

[0052] As a preferred embodiment, the alkali neutralization treatment comprises: adding an alkali reagent to the mixed solution and adjusting the pH of the mixed solution to 7; and then separating the solid and the liquid to obtain aluminum slag and a second reaction solution.

[0053] (3) Controlling the potential of the second reaction solution, oxidizing and separating the manganese in the second reaction solution, and obtaining a third reaction solution from which manganese has been removed.

[0054] In this step, sodium persulfate remaining in the reaction solution is used to control the potential oxidation method to oxidize and separate manganese from the second reaction solution containing nickel, cobalt, manganese, lithium and other valuable metal ions.

[0055] As a preferred embodiment, the potential control includes: using the second reaction solution as an electrolyte, setting up a three-electrode system (including a working electrode, a reference electrode and a counter electrode), and controlling the potential of the electrolyte.

[0056] (4) adding the first extractant to the third reaction liquid to separate the trace elements and obtain a fourth liquid phase.

[0057] As a preferred embodiment, the first extractant includes P204 and N235; in the art, the extractant P204 refers to di(2-ethylhexyl)phosphate, and the extractant N235 refers to trioctyldecyl tertiary amine. In the present invention, the two extractants can be used in synergy to deeply purify, extract and separate trace elements such as iron and manganese in the solution.

[0058] As a more preferred embodiment, the volume ratio of P204 and N235 is (1-5): (1-5); including but not limited to 1:1, 1:2, 1:3, 1:4, 1:5, 2:1, 2:3, 2:5, 3:1, 3:2, 3:4, 3:5, 4:1, 4:3, 4:5, 5:1, 5:2, 5:3, 5:4, any one or a ratio interval consisting of any two of them.

[0059] (5) adding a second extractant to the fourth liquid phase to separate a liquid phase containing cobalt and a fifth liquid phase; and extracting and purifying the liquid phase containing cobalt with sulfuric acid to obtain cobalt sulfate.

[0060] As a preferred embodiment, the second extractant includes Cyanex272; in the art, the extractant Cyanex272 includes the organic phosphoric acid compound di(2,4,4-trimethylpentyl)phosphinic acid.

[0061] As a preferred embodiment, the purification comprises the following steps: adding sodium sulfide to the liquid phase obtained after the back extraction, filtering and removing the filter residue, wherein the main components of the filter residue include nickel sulfide or cobalt sulfide, etc.; in some more preferred embodiments, the filter residue obtained here can be returned to the starting step of step (2), that is, combined with the first material.

[0062] As a preferred embodiment, after adding the second extractant to the fourth liquid phase, an organic phase containing cobalt may be separated; the organic phase can be passed through a sulfuric acid solution and then dissolved together with the aluminum slag obtained in step (2), and the dissolved slag obtained after filtering the dissolved solution can be used as slag for nickel-iron smelting.

[0063] (6) adding a third extractant to the fifth liquid phase to separate a liquid phase containing nickel and a sixth liquid phase; and extracting the liquid phase containing nickel with sulfuric acid to obtain nickel sulfate.

[0064] As a preferred embodiment, the third extractant includes P507; in the art, the extractant P507 includes 2-ethylhexyl mono-2-ethylhexyl phosphate.

[0065] As a preferred embodiment, the extraction and back-extraction involved in the present invention do not provide the amount of the extracting solution used; those skilled in the art can make adaptive adjustments based on the content of the ions to be extracted in the solution; since the types and contents of valuable metals in waste batteries vary greatly, the present invention does not impose strict restrictions on the amount of extracting solution used.

[0066] (7) Treating the sixth liquid phase with an ion exchange resin to obtain lithium sulfate.

[0067] In this step, the lithium in the solution is adsorbed and recovered by ion exchange method to obtain lithium sulfate and return it to industrial production for application. As a preferred embodiment, the adsorbed liquid after being treated with the ion exchange resin is returned to the starting step of step (2) to be combined with the first material.

[0068] As a preferred embodiment, the ion exchange resin includes one of a strong acid resin or a chelating resin; including but not limited to Amberlyst 35 or Amberlite IRC748.

[0069] As a preferred embodiment, after the ion exchange resin treatment, the resin is backwashed with sulfuric acid to obtain lithium sulfate.

[0070] The second aspect of the present invention is to provide a method for treating waste lithium batteries, including the waste lithium battery recycling method.

[0071] Test example

[0072] (1) To verify that ultrasonic cleaning technology has a good stripping effect on the positive electrode of the battery cell; copper foil current collector (LiCoO2 active material loaded on both sides) is used as an example for verification; the positive electrode material for the test is cut into square fragments, divided into three parts, and placed in equal volumes of water. (a) The liquid containing the positive electrode fragments is treated by stirring at a stirring intensity of 500 rpm for a total of 60 minutes; (b) The liquid containing the positive electrode fragments is treated by ultrasound at an ultrasound intensity of 50 kHz for a total of 30 minutes; (c) The above method steps (a) and (b) are performed simultaneously. Figure 2 The figure shows the actual object after processing. It can be clearly seen by naked eyes that the corresponding results of method (a) and method (b) are Figure 2 (a) Figure 2 In (b), most of the current collector surface coating is not peeled off. Figure 2 (b) There is only some peeling at the edge, while method (c) corresponds to the obtained Figure 2 In (c), the coating is completely peeled off and the obvious silver-white aluminum foil current collector is exposed.

[0073] (2) Further verify that the acidity and alkalinity of the water medium in the ultrasonic cleaning technology has a good stripping effect on the positive electrode of the battery cell; the same test sample as the above test example (1) was used for verification; the ultrasonic media used were water, dilute sulfuric acid solution and oxalic acid solution (the acid concentration was 1.5 mol / L), respectively. After ultrasonic treatment at 50 kHz and 50 W for 6 minutes, the mass of the positive electrode material stripped from the aluminum foil was counted and the separation efficiency was calculated. When the ultrasonic media were water, dilute sulfuric acid solution and oxalic acid solution, respectively, the separation efficiency was 46%, 99% and 100%, respectively.

[0074] (3) To verify that the extractant Cyanex272 can achieve the extraction function of Co, the CL-Cyanex272 leaching resin was immersed in a fourth liquid phase obtained by the recovery method according to the present invention; Figure 3 As shown in the figure, the resin before and after immersion was characterized by metallographic electron microscopy. Figure 3 (a) corresponds to the leaching resin before immersion, Figure 3 (b) corresponds to the leaching resin after immersion; Figure 3 It was found that there was no obvious change in the resin morphology before and after the adsorption of Co, but a peak of the Co element appeared in the element distribution spectrum of the resin after adsorption, indicating that Co was successfully adsorbed on the CL-Cyanex272 leaching resin.

[0075] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for recycling waste lithium batteries, characterized in that: The recovery method comprises the following steps: (1) disassembling waste lithium batteries to obtain positive electrode sheets; performing ultrasonic cleaning on the positive electrode sheets to obtain a first material; (2) immersing the first material in a sulfuric acid solution of sodium sulfite to perform a reduction pressure leaching treatment to obtain a mixed solution containing valuable metal ions; performing an alkali neutralization treatment on the mixed solution to obtain aluminum slag and a second reaction solution; (3) controlling the potential of the second reaction solution, oxidizing and separating the manganese in the second reaction solution, and obtaining a manganese-free third reaction solution; (4) adding the first extractant to the third reaction liquid to separate the trace elements and obtain a fourth liquid phase; (5) adding a second extractant to the fourth liquid phase to separate and obtain a liquid phase containing cobalt and a fifth liquid phase; The cobalt-containing liquid phase is stripped and purified by sulfuric acid to obtain cobalt sulfate; (6) adding a third extractant to the fifth liquid phase to separate a nickel-containing liquid phase and a sixth liquid phase; extracting the nickel-containing liquid phase with sulfuric acid to obtain nickel sulfate; (7) Treating the sixth liquid phase with an ion exchange resin to obtain lithium sulfate.

2. The method for recycling waste lithium batteries according to claim 1, characterized in that: The ultrasonic intensity of the ultrasonic cleaning process is 20kHz to 1MHz, and the duration of the ultrasonic cleaning process is 15min to 60min.

3. The method for recycling waste lithium batteries according to claim 1, characterized in that: During the ultrasonic cleaning process, the ultrasonic cleaning liquid is continuously stirred; Preferably, the stirring frequency is 50 rpm to 1000 rpm.

4. The method for recycling waste lithium batteries according to claim 1, characterized in that: The ultrasonic cleaning treatment in step (1) further includes crushing and screening; wherein the mesh size of the screening is 150-300 meshes.

5. The method for recycling waste lithium batteries according to claim 1, characterized in that: The pressure of the pressurized leaching treatment is 0.3 MPa to 3.5 MPa.

6. The method for recycling waste lithium batteries according to claim 1, characterized in that: The first extractant includes P204 and N235; Preferably, the volume ratio of P204 and N235 is (1-5): (1-5).

7. The method for recycling waste lithium batteries according to claim 1, characterized in that: The second extractant comprises Cyanex272; And / or, the third extractant includes P507.

8. The method for recycling waste lithium batteries according to claim 1, characterized in that: In step (5), the purification includes: adding sodium sulfide to the liquid phase obtained after the back extraction, and removing the solid phase components through solid-liquid separation.

9. The method for recycling waste lithium batteries according to claim 1, characterized in that: The ion exchange resin includes one of a strong acid resin or a chelating resin; Preferably, the adsorbed liquid treated with the ion exchange resin is combined with the first material.

10. A method for treating waste lithium batteries, characterized in that: The processing method includes the method for recycling waste lithium batteries as described in any one of claims 1 to 9.

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