Method for recycling lithium battery cathode material

Abstract

This application provides a method for recycling lithium battery cathode materials, comprising the following steps: providing powdered cathode material; mixing powdered lignite, ammonium sulfide, and cathode material in a mass ratio of 0.4:0.5:1 to 2:1:1 to obtain a first mixture; calcining the first mixture at 400°C to 800°C for 1 to 3 hours to obtain a first calcined product; leaching the first calcined product with water to obtain a first mixed solution enriched with lithium and manganese and a first sludge enriched with nickel and cobalt; adjusting the pH of the first mixed solution to 9 to 10 and reacting for 1.5 to 2.5 hours; and performing solid-liquid separation to obtain a second mixed solution enriched with lithium and a second sludge enriched with manganese. This method for recycling lithium battery cathode materials, through carbon-sulfur synergy, rapidly separates lithium and manganese metals from nickel and cobalt metals in the pyrometallurgical stage, and eliminates the need for any acidic reagents in the wet leaching stage, achieving efficient and environmentally friendly separation and extraction of various valuable metals.

Description

Technical Field

[0001] This application relates to the field of new energy, and in particular to a method for recycling lithium battery cathode materials. Background Technology

[0002] Lithium-ion batteries, as high-performance energy storage and power batteries, are widely used in society. However, their lifespan is relatively limited, generally between 3 and 7 years. According to data from the Ministry of Industry and Information Technology, by 2025, my country's cumulative retired battery capacity will reach 125 GWh, with ternary lithium-ion batteries accounting for up to 50%, and an annual compound growth rate of 70%. The large number of discarded lithium-ion batteries will put enormous pressure on the environment and resource recycling. Therefore, adopting efficient and feasible recycling methods to harmlessly treat used lithium-ion batteries, such as recycling their valuable components, is particularly important.

[0003] Currently, there are two main methods for recycling spent lithium-ion batteries: pyrometallurgy and hydrometallurgy. Pyrometallurgical recycling mainly includes traditional smelting and reduction roasting, which recovers valuable metals by applying high temperatures. It has advantages such as a short process and ease of operation, and in my country, it can be easily implemented by modifying corresponding traditional pyrometallurgical equipment. However, pyrometallurgy is energy-intensive and highly polluting, which does not conform to the concept of green and environmentally friendly development. Hydrometallurgy mainly refers to leaching valuable metals into a solution using acids or alkalis, followed by solvent extraction, precipitation, electrodeposition, etc., to obtain valuable metal salts and other products. Hydrometallurgy has advantages such as low energy consumption and a better working environment, but the process is cumbersome and can easily cause secondary pollution. To overcome the inherent defects of the above two methods and achieve low energy consumption and low cost in the recycling process, some researchers have developed methods for extracting valuable transition metal elements after pre-extracting lithium. Xie Jingzhi (CN114368766A) uses a method of mixing battery powder with carbon and roasting to preferentially extract lithium carbonate, which can achieve a certain degree of metal separation. However, due to the inherent defects of lithium carbonate, lithium loss is easy to occur. Hu Jiayan (CN113930619A) achieves a certain degree of efficient lithium extraction by extracting lithium with concentrated sulfuric acid. The obtained nickel-cobalt-manganese product can be directly used for the preparation of ternary precursors. However, this method does not further separate nickel, cobalt, and manganese, which limits the application space of lithium removal slag.

[0004] How to solve the above problems and provide a method for recycling lithium battery cathode materials with low energy consumption, low pollution, and high utilization rate is something that those skilled in the art need to consider. Summary of the Invention

[0005] In view of this, embodiments of this application provide a method for recycling lithium battery cathode materials that has low energy consumption, low pollution, and high utilization rate.

[0006] This application provides a method for recycling lithium battery cathode materials, including the following steps:

[0007] Provides powdered cathode materials for ternary lithium batteries;

[0008] Powdered lignite and powdered ammonium sulfide are provided. The lignite, ammonium sulfide and cathode material are mixed in a mass ratio of 0.4:0.5:1 to 2:1:1 to obtain a first mixture. The first mixture is calcined at 400°C to 800°C for 1 to 3 hours to obtain a first calcined product.

[0009] The first roasted product was soaked in water to obtain a first mixed solution enriched with lithium and manganese and a first sludge enriched with nickel and cobalt.

[0010] The pH of the first mixed solution is adjusted to a range of 9 to 10, the pH is maintained stable, and solid-liquid separation is carried out for 1.5 to 2.5 hours to obtain a second mixed solution enriched with lithium and a second sludge enriched with manganese.

[0011] In one possible implementation, the method further includes the following steps: heating the second mixed solution to 90°C to 95°C and passing a carbonate solution through it, thereby separating the solid and liquid phases to obtain a third sludge enriched with lithium.

[0012] In one possible implementation, the carbonate solution is a saturated solution of sodium carbonate or a saturated solution of potassium carbonate, and the third sludge is enriched with lithium carbonate.

[0013] In one possible implementation, the first calcination product includes nickel sulfide, cobalt sulfide, manganese sulfate, and lithium sulfate.

[0014] In one possible implementation, the first mixed solution is enriched with manganese sulfate and lithium sulfate, and the first sludge is enriched with nickel sulfide and cobalt sulfide.

[0015] In one possible implementation, ammonia is added to the first mixed solution to adjust its pH value to the range of 9 to 10.

[0016] In one possible implementation, the second sludge is enriched with a mixture of Mn(OH)2 and MnO(OH).

[0017] In one possible implementation, during the roasting of the lignite, ammonium sulfide, and cathode material to obtain the first roasting product, the overall reaction formula is:

[0018] 2LiNi a Co b Mn cO2+C+3(NH4)2S+(3+3.5c-0.5a-0.5b)O2→Li2SO4+2cMnSO4+2aNiS+2bCoS+CO2+6NH3+3H2O.

[0019] In one possible implementation, the first sediment is washed, and the washing solution is added to the second mixed solution.

[0020] In one possible implementation, the step of providing a powdered positive electrode material for a ternary lithium battery includes: immersing waste lithium-ion battery positive electrode material in an organic solvent containing N-methylpyrrolidone, filtering to remove the binder, then removing the electrode sheet and calcining it at a temperature of 550°C to 600°C for 1 to 3 hours, drying and pulverizing it to obtain the powdered positive electrode material.

[0021] Compared to existing technologies, this application presents an industrial-scale method for the stepwise recycling of valuable metals from waste ternary lithium ions through a simple roasting process. By leveraging the synergistic effect of carbon and sulfur, lithium manganese metals can be directly and rapidly separated from nickel and cobalt metals during the pyrometallurgical stage. The wet leaching stage requires no acidic reagents, achieving efficient and environmentally friendly separation and extraction of various valuable metals. This solves the problems of easy loss of valuable metals and difficulty in separating nickel, cobalt, and manganese in conventional methods.

[0022] In the lithium battery cathode material recycling method of this application, each valuable metal has different sulfur-oxygen affinity characteristics under the same sulfur potential and oxygen potential, which makes different metal compounds gradually generated during the roasting process. Through the different solubility properties of these metal compounds, it becomes possible to directly separate different valuable metals by simple water immersion, thereby obtaining relatively pure lithium, manganese and nickel-cobalt products respectively. Attached Figure Description

[0023] Figure 1 This is a schematic flowchart illustrating a method for recycling lithium battery cathode materials provided in an embodiment of this application.

[0024] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0025] The following description will refer to the accompanying drawings to provide a more complete picture of the present application. The drawings illustrate exemplary embodiments of the present application. However, the present application may be implemented in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. These exemplary embodiments are provided to make the present application thorough and complete, and to fully convey the scope of the present application to those skilled in the art. Similar reference numerals denote the same or similar components.

[0026] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to limit the application. As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” are intended to also include the plural forms. Furthermore, when used herein, “comprising” and / or “including” and / or “having,” integers, steps, operations, components, and / or components, but does not exclude the presence or addition of one or more other features, regions, integers, steps, operations, components, and / or groups thereof.

[0027] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Furthermore, unless expressly defined herein, terms such as those defined in a general dictionary should be interpreted as having the same meaning as they have in the relevant art and in the content of this application, and will not be interpreted as having an idealized or overly formal meaning.

[0028] The specific embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0029] like Figure 1 As shown in the figure, this application provides a method for recycling lithium battery cathode materials, including the following steps:

[0030] Step S1: Provide powdered positive electrode material for ternary lithium batteries.

[0031] In one embodiment, the step of providing a powdered positive electrode material for a ternary lithium battery includes: immersing waste lithium-ion battery positive electrode material in an organic solvent containing N-methylpyrrolidone (NMP), filtering to remove the binder, then removing the electrode sheet and calcining it at a temperature of 550°C to 600°C for 1 to 3 hours, drying and pulverizing it to obtain the powdered positive electrode material.

[0032] The binder on the positive electrode sheet can be removed by soaking in organic solvents and calcining, thereby eliminating the negative impact of substances such as current collectors adhering to the positive electrode material. After soaking in organic solvents and calcining, the electrode sheet is removed, cooled to room temperature, peeled off, and dried positive electrode active material is obtained.

[0033] Step S2: Provide powdered lignite and powdered ammonium sulfide, mix the lignite, ammonium sulfide and cathode material in a mass ratio of 0.4:0.5:1 to 2:1:1 to obtain a first mixture, and calcine the first mixture at 400°C to 800°C for 1 to 3 hours to obtain a first calcined product.

[0034] In one embodiment, during the roasting of the lignite, ammonium sulfide, and cathode material to obtain the first roasted product, the reaction between ammonium sulfide and lignite includes:

[0035] (NH4)2S(s)→(NH4)2S(g)→2NH3(g)+H2S(g)

[0036] 2H2S(g)+3O2(g)→2SO2(g)+2H2O(g)

[0037] 2C(s)+2SO2(g)→2CO2(g)+S2(g).

[0038] By leveraging the rapid mass transfer and heat characteristics of the gas-solid reaction during air roasting, the conversion of metal oxides into sulfur-containing metal compounds is achieved, while the efficient utilization of elemental sulfur is realized through carbothermic drive.

[0039] Lignite, as a low-cost carbon source, can reduce production costs. Furthermore, the presence of carbon not only regulates the sulfur potential (lg(Ps2 / Pso2)) in the roasting atmosphere but also provides the necessary heat for the reaction, reducing energy consumption. The overall reaction formula for roasting the lignite, ammonium sulfide, and cathode material to obtain the first roasted product is:

[0040] 2LiNi a Co b Mn c O2+C+3(NH4)2S+(3+3.5c-0.5a-0.5b)O2→Li2SO4+2cMnSO4+2aNiS+2bCoS+CO2+6NH3+3H2O.

[0041] In this process, lithium and manganese are selectively sulfated into soluble sulfates, while elements such as nickel and cobalt exist in the form of water-insoluble sulfides or sulfur oxides. The first calcination product obtained is lithium sulfate, manganese sulfate, sulfides or sulfur oxides of nickel and cobalt, as well as impurities such as residual carbon powder and sulfur powder.

[0042] In other words, the lithium and manganese in the resulting roasted products mainly exist in the form of sulfates, while nickel and cobalt mainly exist in the form of sulfides or sulfur oxides (such as NiS and CoS). Since lithium and manganese form compounds with different solubility properties compared to nickel and cobalt, they can be separated from nickel and cobalt through water leaching and solid-liquid separation. This separation process is low-cost and rapid, and does not require the addition of acid, thus avoiding many of the troublesome problems associated with acid contamination treatment during leaching processes.

[0043] Furthermore, the trace amounts of sulfur oxide gas released during the experiment can be fully absorbed by a gas absorption device containing NaOH alkaline solution, making the treatment relatively easy and giving the method a certain degree of practicality and environmental friendliness.

[0044] Furthermore, in the above reaction, the ammonia gas produced after the ammonium sulfide reaction can be collected and used to produce ammonia water. The produced ammonia water can be used for the precipitation of manganese in subsequent steps, which can reduce the need for additional alkali solution and thus reduce costs. In addition, the ammonia gas produced can also be used to produce and be used as an alkaline neutralization solvent in the aforementioned tail gas absorption reaction, further reducing the overall cost of the reaction and improving environmental friendliness.

[0045] In one embodiment, the first calcination product includes nickel sulfide, cobalt sulfide, manganese sulfate, and lithium sulfate.

[0046] Step S3: Immerse the first roasted product in water to obtain a first mixed solution enriched with lithium and manganese and a first sludge enriched with nickel and cobalt.

[0047] In one embodiment, the first mixed solution is enriched with manganese sulfate and lithium sulfate, and the first sludge is enriched with nickel sulfide and cobalt sulfide.

[0048] After cooling the first calcined product obtained in step S2 to room temperature, it is heated, stirred, and soaked in water to obtain a first mixed solution and a first sludge. The first sludge is washed again to obtain a washing liquid and a washing residue. The washing liquid is added to the first mixed solution. The purpose of washing is to reduce the loss of valuable metals that may be caused by carbon powder encapsulation.

[0049] Step S4: Adjust the pH of the first mixed solution to a range of 9 to 10, maintain the pH value stable, and react for 1.5 to 2.5 hours to perform solid-liquid separation, thereby obtaining a second mixed solution enriched with lithium and a second sludge enriched with manganese.

[0050] In one embodiment, ammonia is added to the first mixed solution to adjust its pH value to a range of 9 to 10. This ammonia can be produced from the ammonia gas generated in the aforementioned sulfur-carbon synergistic reaction, further improving material utilization and environmental friendliness.

[0051] In one embodiment, the second sludge is enriched with a mixture of Mn(OH)2 and MnO(OH).

[0052] Step S5: The second mixed solution is heated to 90°C to 95°C and a carbonate solution is introduced to separate the solid and liquid phases and obtain a third sludge enriched with lithium.

[0053] In one embodiment, the carbonate solution is a saturated solution of sodium carbonate or a saturated solution of potassium carbonate, and the third sludge is enriched with lithium carbonate.

[0054] The term "enrichment" as used in this application can be understood as the presence of a certain compound primarily in a mixed solution or sludge, or as the concentration of a compound of a certain element mainly in the separated solution or sludge during solid-liquid separation. For example, in step S3, lithium and manganese and their compounds are mainly separated into the first mixed solution. The first sludge may contain lithium and manganese and their compounds, but the amount of lithium and manganese and their compounds in the first sludge is much less than the amount of lithium and manganese and their compounds in the first mixed solution. Similarly, nickel and cobalt and their compounds are mainly separated into the first sludge. The first mixed solution may contain nickel and cobalt and their compounds, but the amount of nickel and cobalt and their compounds in the first mixed solution is much less than the amount of nickel and cobalt and their compounds in the first sludge.

[0055] This application presents an industrial-scale method for the stepwise recycling of valuable metals from waste ternary lithium ions through a simple roasting process. By using carbon-sulfur synergy, lithium manganese metals can be directly and rapidly separated from nickel and cobalt metals in the pyrometallurgical stage. No acidic reagents are required in the wet leaching stage. This method achieves efficient and green separation and extraction of various valuable metals, solving the problems of easy loss of valuable metals and difficulty in separating nickel, cobalt, and manganese in conventional methods.

[0056] In the lithium battery cathode material recycling method of this application, each valuable metal has different sulfur-oxygen affinity characteristics under the same sulfur potential and oxygen potential, which makes different metal compounds gradually generated during the roasting process. Through the different solubility properties of these metal compounds, it becomes possible to directly separate different valuable metals by simple water immersion, thereby obtaining relatively pure lithium, manganese and nickel-cobalt products respectively.

[0057] The lithium battery cathode material recycling method proposed in this application is not only simple in process and has high added value, but also has low energy consumption and no secondary pollution, which is in line with the development concept of green metallurgy. This method can achieve efficient and comprehensive utilization of valuable metals through stepwise sulfidation.

[0058] Example 1

[0059] Step S1: Preparation of positive electrode active powder: After soaking the waste lithium-ion battery positive electrode sheet in N-methylpyrrolidone (NMP) organic solvent for several hours, remove the sheet and place it in a high-temperature tube furnace at 550°C to 600°C for 1 to 3 hours. During this process, toxic gases may be generated due to the volatilization and decomposition of organic matter, which need to be absorbed using a gas recovery device. After calcination, the positive electrode material is peeled off from the current collector to obtain a dry powdered positive electrode material.

[0060] Step S2: Carbon-sulfur co-calcination: The lignite powder, ammonium sulfide powder and powdered cathode material are ball-milled and mixed evenly at a mass ratio of 0.8:0.8:1. 10g of the mixture is placed in an alumina crucible and calcined in a tube furnace at 600℃ for 1 hour. After heating, the calcined product is cooled to room temperature with the furnace and then taken out.

[0061] Step S3: Water leaching separation: The roasted product from step S2 is dissolved in deionized water at a solid-liquid ratio of 1g:10mL. After leaching with heating and stirring for a period of time, solid-liquid separation is performed using a Buchner funnel. The filter residue is a solid residue containing nickel and cobalt sulfides or sulfur oxides and other impurities, while the filtrate is an aqueous solution mainly containing lithium and manganese sulfates. ICP analysis shows that the leaching rate of lithium is over 95%, the leaching rate of manganese is over 90%, and the leaching rates of other valuable metals (such as nickel and cobalt) are all below 5%.

[0062] Step S4: Separation of lithium and manganese: Adjust the pH of the filtrate obtained in step S3 to 9 or 10 with a pH adjuster (such as ammonia), react for 2 hours at a stable pH, and then filter to obtain manganese-containing filter residue and lithium-rich solution.

[0063] Step S5: Preparation of lithium carbonate product: The lithium-rich liquid obtained in step S4 is heated to 90°C to 95°C and kept at that temperature for 60 minutes. Then, a saturated sodium carbonate solution is slowly added while stirring. After being kept at that temperature for a period of time, the mixture is filtered. The filter residue is thoroughly washed with hot water at about 95°C and dried to obtain lithium carbonate. The purity of the lithium carbonate is tested to be above 98%.

[0064] Example 2

[0065] The specific process is the same as in Example 1. The ratio of the mixture in step S2 is 2:1:1, and other conditions remain unchanged. According to the detection of the first mixed solution (i.e., the first filtrate) by inductively coupled plasma optical emission spectrometry, the leaching rate of lithium manganese is slightly reduced, while the leaching rate of nickel and cobalt remains basically unchanged.

[0066] Example 3

[0067] The specific process is the same as in Example 1. The mixing ratio of the materials in step S2 is 0.4:0.5:1, and other conditions remain unchanged. According to the detection of the first mixed solution (i.e., the first filtrate) by inductively coupled plasma optical emission spectrometry, the leaching rate of lithium manganese has decreased, while the leaching rate of nickel and cobalt remains basically unchanged.

[0068] Example 4

[0069] The specific process is the same as in Example 1. The calcination temperature in step S3 is 400°C, and other conditions remain unchanged. According to the detection of the first mixed solution (i.e., the first filtrate) by inductively coupled plasma optical emission spectrometry, the lithium leaching rate remains basically unchanged, while the nickel, cobalt and manganese leaching rates all increase.

[0070] Example 5

[0071] The specific process is the same as in Example 1. The calcination temperature in step S3 is 800°C, and other conditions remain unchanged. According to the detection of the first mixed solution (i.e., the first filtrate) by inductively coupled plasma optical emission spectrometry, the leaching rate of lithium nickel cobalt manganese has decreased.

[0072] The specific embodiments of this application have been described above with reference to the accompanying drawings. However, those skilled in the art will understand that various changes and substitutions can be made to the specific embodiments of this application without departing from the scope of this application. All such changes and substitutions fall within the scope defined by this application.

Claims

1. A method for recycling lithium battery cathode material, characterized in that, Includes the following steps: Provides powdered cathode materials for ternary lithium batteries; Powdered lignite and powdered ammonium sulfide are provided. The lignite, ammonium sulfide and cathode material are mixed in a mass ratio of 0.4:0.5:1 to 2:1:1 to obtain a first mixture. The first mixture is calcined at 400°C to 800°C for 1 to 3 hours to obtain a first calcined product. The first calcined product includes nickel sulfide, cobalt sulfide, manganese sulfate and lithium sulfate. The first roasted product was soaked in water to obtain a first mixed solution enriched with lithium sulfate and manganese sulfate and a first sludge enriched with nickel sulfide and cobalt sulfide. Ammonia is added to the first mixed solution to adjust the pH value of the first mixed solution to the range of 9 to 10. The pH value is maintained and the reaction is carried out for 1.5 to 2.5 hours to perform solid-liquid separation, thereby obtaining a second mixed solution enriched with lithium and a second sludge enriched with a mixture of Mn(OH)2 and MnO(OH). The first sludge is washed and the washing water is added to the second mixed solution.

2. The method for recycling lithium battery cathode material as described in claim 1, characterized in that, The method also includes the following steps: heating the second mixed solution to 90°C to 95°C and passing a carbonate solution through it, and separating the solid and liquid to obtain a third sludge enriched with lithium.

3. The method for recycling lithium battery cathode material as described in claim 2, characterized in that, The carbonate solution is a saturated solution of sodium carbonate or a saturated solution of potassium carbonate, and the third sludge is enriched with lithium carbonate.

4. The method for recycling lithium battery cathode material as described in claim 1, characterized in that, In the process of roasting the lignite, ammonium sulfide, and cathode material to obtain the first roasting product, the overall reaction formula is: 2LiNi a Co b Mn c O2+C+3(NH4)2S+(3+3.5c-0.5a-0.5b)O2→Li2SO4+2aNiS+2bCoS+CO2+6NH3+3H2O.

5. The method for recycling lithium battery cathode material as described in claim 1, characterized in that, The steps for providing powdered positive electrode material for ternary lithium batteries include: soaking waste lithium-ion battery positive electrode material in N-methylpyrrolidone organic solvent and filtering it to remove binder, then taking out the electrode sheet and calcining it at a temperature of 550°C to 600°C for 1 to 3 hours, drying it and pulverizing it to obtain the powdered positive electrode material.

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