A method for extracting lithium element from waste batteries

Abstract

The application provides a method for extracting lithium from waste batteries, which comprises the following steps: (1) pretreatment: obtaining waste ternary positive materials, and pretreating the waste ternary positive materials to obtain black powder; (2) reduction roasting treatment: roasting the black powder to obtain roasted powder; (3) acid dissolution treatment: performing acid dissolution reaction of the roasted powder and a sulfuric acid solution to obtain a solid-liquid mixture; the molar ratio of Li element in the roasted powder to H element in the sulfuric acid solution is 1:(0.98-1.3); (4) electrolysis treatment: performing electrolysis of the solid-liquid mixture, and after electrolysis, filtering to obtain filter residue and a lithium-containing solution. By using the method provided by the application, the recovery rate of lithium is increased to more than 98%.

Description

Technical Field

[0001] This application relates to the field of battery recycling technology, and in particular to a method for extracting lithium from waste batteries. Background Technology

[0002] With the continuous expansion of the electric vehicle and renewable energy markets, lithium batteries, as an important energy storage device, have been widely used in automobiles, power tools, mobile devices, and other fields due to their high energy density and long lifespan. However, the recycling and disposal of used batteries remains a global challenge. Once batteries are damaged or reach the end of their lifespan, a large number of used batteries are generated, posing potential pollution and resource waste problems to the environment. Among them, lithium batteries using ternary materials as the positive electrode active material are particularly widely used.

[0003] Currently, the main method for recovering valuable metal elements from ternary lithium batteries is the wet process, which involves acid leaching followed by extraction or precipitation. For example, reducing agents and acids can be added to the black powder to completely dissolve it, and the pH of the solution can be adjusted to 1, which requires a large amount of acid. Alternatively, acid and hydrogen peroxide can be used for treatment followed by extraction, which requires a large amount of acid, alkali, and extractant, and the lithium recovery rate is low, only about 92%. Summary of the Invention

[0004] The purpose of this application is to provide a method for extracting lithium from spent batteries, thereby improving the lithium recovery rate and eliminating the need for reducing agents and reducing the use of acid in the acid dissolution process. The specific technical solution is as follows:

[0005] This application provides a method for extracting lithium from waste batteries, which includes the following steps:

[0006] (1) Pretreatment: Obtain waste ternary cathode material, and pretreat the waste ternary cathode material to obtain black powder;

[0007] (2) Reduction roasting treatment: The black powder is reduced and roasted to obtain roasted powder;

[0008] (3) Acid dissolution treatment: The calcined powder is subjected to acid dissolution reaction with sulfuric acid solution to obtain a solid-liquid mixture; the molar ratio of Li element in the calcined powder to H element in the sulfuric acid solution is 1:(0.98~1.3);

[0009] (4) Electrolysis treatment: The solid-liquid mixture is electrolyzed, and after the electrolysis is completed, the residue and lithium-containing solution are obtained by filtration.

[0010] In some embodiments of this application, step (2), the reduction calcination of the black powder, includes:

[0011] The black powder is calcined in the presence of a reducing agent, which includes C and / or CO; and in step (2), the calcined powder obtained includes Li2CO3 and Me-containing powder; wherein the Me-containing powder includes elemental Me and / or MeO; and the Me is selected from at least one of Ni, Co, and Mn elements.

[0012] In some embodiments of this application, in step (3), the molar ratio of Li element in the calcined powder to H element in the sulfuric acid solution is 1:(1.01~1.1).

[0013] In some embodiments of this application, in step (3), the solid-liquid mixture comprises a liquid phase and a solid phase, wherein the liquid phase contains Li2SO4 and MeSO4, and the solid phase contains Li2CO3 and Me-containing powder.

[0014] In some embodiments of this application, in step (3), in the liquid phase, the molar amount of Li in Li2SO4 is p1, and the molar amount of Me in MeSO4 is p2, satisfying p1 > p2; in the solid phase, the molar amount of Me in the Me-containing powder is p3, and the molar amount of Li in Li2CO3 is p4, satisfying p3 > p4.

[0015] In some embodiments of this application, in step (3), the first lithium elution rate after acid dissolution treatment is 88% to 92%.

[0016] In some embodiments of this application, step (4) of electrolyzing the solid-liquid mixture includes electrolyzing the MeSO4 in the liquid phase of the solid-liquid mixture.

[0017] In some embodiments of this application, in step (4), the conditions for the end of electrolysis include: for every 100g of the black powder, when the electrolysis capacity C1 in the electrolysis process satisfies Equation 1, the electrolysis ends;

[0018] 10Ah≤C1 (Equation 1)

[0019] In some embodiments of this application, in step (4), the conditions for the end of electrolysis include: for every 100g of the black powder, the first lithium elution rate after the acid dissolution treatment in step (3) is 88% to 90%, and the electrolysis is ended when the electrolysis capacity C1 in the electrolysis process satisfies formula 1-a;

[0020] 11Ah≤C1≤13Ah, formula 1-a.

[0021] In some embodiments of this application, in step (4), the conditions for the end of electrolysis include: for every 100g of the black powder, the first lithium elution rate after the acid dissolution treatment in step (3) is 90% to 92%, and the electrolysis ends when the electrolysis capacity C1 in the electrolysis process satisfies formula 1-b;

[0022] 10Ah≤C1≤12Ah (Equation 1-b)

[0023] In some embodiments of this application, in step (4), the lithium-containing solution includes Li2SO4; in the lithium-containing solution, the mass of the Li2SO4 is n1, satisfying n1 > m1, where m1 is the mass of the Li2SO4 in the liquid phase of the solid-liquid mixture in step (3).

[0024] In some embodiments of this application, in step (4), the second lithium elution rate of the lithium-containing solution is ≥98%.

[0025] In some embodiments of this application, in step (4), the filter residue includes the Me-containing powder; the mass percentage of the Me-containing powder in the filter residue is w1%; satisfying: w1% > w2%; wherein w2% is the mass percentage of the Me-containing powder in the solid phase in the solid-liquid mixture in step (3).

[0026] In some embodiments of this application, in step (4), the electrolysis further yields an anode product and a cathode product; the anode product includes MnO2; the cathode product includes at least one of elemental Ni and elemental Co.

[0027] In some embodiments of this application, at least one of the following conditions is met:

[0028] Condition a: In step (2), the amount of the reducing substance used is 8 wt% to 15 wt% of the black powder;

[0029] Condition b: In step (2), the reduction calcination temperature T3 is 550℃~700℃, and the calcination time t3 is 1h~3h;

[0030] Condition c: In step (3), the concentration of the sulfuric acid solution is 1 mol / L to 5 mol / L;

[0031] Condition d: In step (4), the voltage U1 of the electrolysis is 2.5V to 4.5V and the temperature T1 is 30℃ to 80℃.

[0032] The beneficial effects of this application are:

[0033] This application provides a method for extracting lithium from waste batteries. The method first involves roasting the black powder from the waste batteries with a reducing agent, then performing acid dissolution treatment by controlling the amount of acid, and finally electrolytically leaching the lithium into the liquid phase. This process removes most of the nickel, cobalt, and manganese in powder form, improving the lithium elution rate (i.e., lithium recovery rate) and yielding high-purity nickel, cobalt, and manganese powder. Specifically, the reduced nickel, cobalt, and manganese become elemental and / or metal oxides, while lithium becomes solid Li₂CO₃. Controlling the amount of acid used in the acid dissolution treatment reduces the amount of acid required and eliminates the need for a reducing agent. Electrolysis then uses the acid generated to dissolve the undissolved solid Li₂CO₃ from the acid dissolution process, further improving the lithium elution rate. The resulting solid powder contains no lithium, and no additional acid is consumed during the electrolysis process. Furthermore, the method only requires crushing the cathode material of the waste ternary lithium batteries and then removing the binder and electrolyte at high temperature. The carbon powder is removed during the reduction and combustion process, reducing energy consumption. Using the method provided in this application to extract lithium from waste batteries, the lithium elution rate can reach over 98%.

[0034] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.

[0036] Figure 1 This is an experimental flowchart of Embodiment 1 of this application. Detailed Implementation

[0037] The technical solutions of this application will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0038] Currently, the main method for recycling valuable metal elements from ternary lithium batteries is the wet process, which requires the use of large amounts of acids, alkalis, and extractants, and results in a low lithium recovery rate. Therefore, this application provides a method for extracting lithium from spent batteries to improve the lithium recovery rate, and eliminates the need for reducing agents and reduces acid usage during the acid dissolution process.

[0039] This application provides a method for extracting lithium from waste batteries, which includes the following steps:

[0040] (1) Pretreatment: Obtain waste ternary cathode material, and pretreat the waste ternary cathode material to obtain black powder;

[0041] (2) Reduction roasting treatment: The black powder is reduced and roasted to obtain roasted powder;

[0042] (3) Acid dissolution treatment: The calcined powder is reacted with sulfuric acid solution to obtain a solid-liquid mixture;

[0043] (4) Electrolysis treatment: The solid-liquid mixture is electrolyzed. After the electrolysis is completed, the residue and lithium-containing solution are obtained by filtration.

[0044] In some embodiments of this application, in step (3), the molar ratio of Li element in the calcined powder to H element in the sulfuric acid solution is 1:(0.98~1.3).

[0045] This application also provides a method for extracting lithium from waste batteries, which includes the following steps:

[0046] (1) Pretreatment: Obtain waste ternary cathode material, and pretreat the waste ternary cathode material to obtain black powder;

[0047] (2) Reduction roasting treatment: The black powder is reduced and roasted to obtain roasted powder;

[0048] (3) Acid dissolution treatment: The calcined powder is subjected to acid dissolution reaction with sulfuric acid solution to obtain a solid-liquid mixture; the molar ratio of Li element in the calcined powder to H element in the sulfuric acid solution is 1:(0.98~1.3);

[0049] (4) Electrolysis treatment: The solid-liquid mixture is electrolyzed. After the electrolysis is completed, the residue and lithium-containing solution are obtained by filtration.

[0050] In this application, ternary cathode material refers to ternary cathode material mainly composed of LiMeO2, wherein Me is selected from at least one of the elements Ni, Co, and Mn.

[0051] The method provided in this application involves calcining black powder with a reducing agent to convert the Me element in the black powder into elemental Me and / or MeO, and the lithium element into solid Li2CO3. A slightly excess of acid is used to dissolve the calcined black powder. During the acid dissolution process, sulfuric acid converts most of the Li2CO3 into the more soluble Li2SO4. Inevitably, a small amount of Me and / or MeO is also dissolved into MeSO4. The dissolved MeSO4, such as nickel sulfate, cobalt sulfate, or manganese sulfate, is then electrolyzed. The acid generated by the electrolysis is used to dissolve the small amount of undissolved solid Li2CO3, improving the lithium elution rate and obtaining a solid powder and a lithium-containing solution. The lithium elution rate of the lithium-containing solution is ≥98%.

[0052] The method provided in this application significantly reduces the amount of sulfuric acid used compared to traditional processes, which typically require SO4 in combination with Li, Co, Ni, and Mn. 2- If calculated using sulfur (S) as the element, 1 mol Li corresponds to 0.5 mol S, and 1 mol Co / Ni / Mn corresponds to 1 mol S. Therefore, the required amount of S moles needs to match the molar amounts of Li, Co, Ni, and Mn. However, in this method, the H₂SO₄ produced during the electrolysis of CoSO₄, NiSO₄, and MnSO₄ can react with the undissolved Li. Therefore, only the amount of SO₄ needed to produce the Li is required. 2- In this process, the molar ratio of Li in the calcined powder to H in the sulfuric acid solution is 1:(0.98~1.3), which reduces the need for sulfuric acid or acidic substances and reducing agents, and also results in a high lithium elution rate.

[0053] Specifically, in the method provided in this application, the molar ratio of Li element in the calcined powder to H element in the sulfuric acid solution is 1:(0.98~1.3), preferably 1:(1.01~1.1). For example, the molar ratio of Li element in the calcined powder to H element in the sulfuric acid solution can be 1:0.98, 1:1.01, 1:1.02, 1:1.04, 1:1.07, 1:1.08, 1:1.1, 1:1.17, 1:1.25, or 1:1.3, or any two of the above numbers. By controlling the amount of sulfuric acid within the above range, most of the Li2CO3 in the calcined powder can be dissolved to generate Li2SO4. Li2SO4 enters the liquid phase of the solid-liquid mixture. At the same time, a small amount of elemental Me and / or MeO in the calcined powder will also react with sulfuric acid to generate MeSO4, which also enters the liquid phase of the solid-liquid mixture. Acid dissolution yields a large amount of Li₂SO₄, a small amount of undissolved solid Li₂CO₃, a large amount of undissolved solid elemental Me and / or MeO, and a small amount of MeSO₄. The large amount of Li₂SO₄ and the small amount of MeSO₄ enter the liquid phase, while the small amount of undissolved solid Li₂CO₃ and the large amount of undissolved solid elemental Me and / or MeO remain in the solid phase. Through acid dissolution, not only can most of the Li₂SO₄ be dissolved... + The Li enters the liquid phase, while most of the Me-containing powder remains in the solid phase. + Separating Me-containing powders using both liquid and solid phases can yield high-purity Me-containing powders. These powders primarily include Ni, Co, and MnO, and Li... + It has a high elution rate in the liquid phase (around 88% to 92%) and fewer impurity phases in the liquid phase.

[0054] In this process, by reasonably controlling H + The amount or SO4 2- The amount of H + The amount of Li + A slight excess of the solution allows for the "stepwise" elution of Li. The first step involves acid washing (H+). + Most of the Li element was eluted from the solid phase and impregnated into the liquid phase. At the same time, the Me element also combined with some SO4. 2- Immersed in the liquid phase, controlling the portion of SO4 bound by Me element. 2-The molar amount of the first step corresponds to the amount of uneluted Li₂CO₃ in the solid phase, preparing for the second step of lithium electrolysis. The second step utilizes the electrolysis of MeSO₄ in the liquid phase to generate H₂SO₄. Since the amount of H₂SO₄ generated corresponds to the amount of uneluted Li₂CO₃ in the solid phase, it allows for the elution of as much Li₂CO₃ as possible from the remaining solid phase, while the Me element remains in the solid phase, i.e., the filter residue. This two-step elution process avoids acid waste and achieves a high overall elution rate (over 98%), while the Me element remains in the solid phase, thus achieving the separation of Li and Me elements.

[0055] If H + Excessive amounts will wash away more elemental Me and / or MeO, reducing the amount of Ni in the liquid phase. 2+ Co 2+ Increased content of certain elements affects the purity of Li₂SO₄, increasing the complexity of subsequent purification and also impacting the recovery rates of nickel, cobalt, and manganese. If H₂... + Too little, Li + The elution rate is low, which is not conducive to lithium recovery, and the Li in the Me-containing powder is also low. + The content will increase, but the purity will be lower, requiring further purification.

[0056] When the molar ratio of Li in the calcined powder to H in the sulfuric acid solution is 1:(1.01~1.1) during acid dissolution, the lithium elution rate is between 88% and 92%, indicating that proper adjustment of the Li content is crucial. + With H + The molar ratio, even if H + A slight excess can make Li + This allows for more thorough separation of Me-containing powders in both liquid and solid phases, further improving the purity of nickel-cobalt-manganese powders, primarily including Ni, Co, and MnO, and Li. + It has a higher elution rate in the liquid phase and fewer impurity phases in the liquid phase.

[0057] In this application, the first lithium elution rate after acid dissolution treatment is 88%–92%. Controlling this range not only achieves a high overall lithium elution rate but also improves the recovery rate and purity of Me. If the first lithium elution rate is too high, more acid will be used, resulting in more Me being eluted, wasting acid and reducing Me recovery, thus affecting Li₂SO₄ purity. If the first lithium elution rate is too low, more Li will remain in the solid phase, hindering Li recovery and reducing solid phase purity.

[0058] In this application, the concentration of sulfuric acid is not strictly required. The concentration of the sulfuric acid solution can be selected from 1 mol / L to 5 mol / L, and further selected from 4.5 mol / L to 5.0 mol / L. For example, when using high-concentration sulfuric acid, such as greater than 5 mol / L, the concentration of sulfuric acid can be diluted with water to make the acid dissolution process easier; or sulfuric acid with a concentration of 1 mol / L to 5 mol / L can be used directly. Selecting sulfuric acid in this concentration range is beneficial to completing the acid dissolution process in a short time, and the acid dissolution reaction will also be more thorough. In some embodiments of this application, in step (2), the reduction roasting of the black powder includes: roasting the black powder in the presence of a reducing substance, the reducing substance including C and / or CO; and, in step (2), the roasted powder obtained includes Li2CO3 and Me-containing powder; wherein, the Me-containing powder includes elemental Me and / or MeO; Me is selected from at least one of Ni, Co, and Mn elements.

[0059] In some embodiments of this application, in step (2), the amount of reducing agent is 8 wt% to 15 wt% of the black powder; the reduction roasting temperature T3 is 550℃ to 700℃, and the roasting time t3 is 1h to 3h. For example, the amount of reducing agent can be 8 wt%, 10 wt%, 12 wt%, 13 wt%, or 15 wt% of the black powder, or any two of the above figures; the reduction roasting temperature T3 can be 550℃, 580℃, 620℃, 650℃, or 700℃, or any two of the above figures; the roasting time t3 can be 1h, 1.5h, 2h, 2.5h, or 3h, or any two of the above figures. By controlling the amount of reducing agent and the reduction roasting temperature and reaction time within the above ranges, the black powder can fully react with the reducing agent, converting the lithium element in the black powder into Li2CO3, and the Me element in the black powder into elemental Me and / or MeO, which is beneficial for subsequent acid dissolution treatment.

[0060] For example, when the reducing agent used in step (2) is C, the reaction equation is:

[0061] 2LiMeO2+C=Li2CO3+Me+MeO.

[0062] When using carbon powder for reduction, an inert gas, such as N2, can be introduced.

[0063] For example, when the reducing agent used in step (2) is CO, the reaction equation is:

[0064] 2LiMeO2+2CO=Li2CO3+Me+MeO+CO2.

[0065] In some embodiments of this application, in step (3), the solid-liquid mixture comprises a liquid phase and a solid phase. The liquid phase contains Li₂SO₄ and MeSO₄, and the solid phase contains Li₂CO₃ and Me-containing powder. In some embodiments of this application, in step (3), in the liquid phase, the molar amount of Li in Li₂SO₄ is p1, and the molar amount of Me in MeSO₄ is p2, satisfying p1 > p2; in the solid phase, the molar amount of Me in the Me-containing powder is p3, and the molar amount of Li in Li₂CO₃ is p4, satisfying p3 > p4. The black powder mainly contains LiMeO₂, and the molar ratio of Li to Me is approximately 1:1. The ratio of the two remains unchanged in the calcined powder obtained after calcination. Sulfuric acid preferentially reacts with Li2CO3 in the calcined powder, and then with elemental Me and / or MeO in the calcined powder. Therefore, most of the Li2CO3 reacts with sulfuric acid to form Li2SO4, while a small amount of elemental Me and / or MeO also reacts with sulfuric acid to form MeSO4. A large amount of Li2SO4 and a small amount of MeSO4 enter the liquid phase, so p1 > p2 in the liquid phase. A small amount of undissolved solid Li2CO3 and a large amount of undissolved solid elemental Me and / or MeO remain in the solid phase, so p3 > p4 in the solid phase.

[0066] In some embodiments of this application, in step (3), the first lithium elution rate after acid dissolution treatment is 88% to 92%. After acid dissolution treatment, most of the Li2CO3 in the calcined powder reacts with sulfuric acid to generate Li2SO4. The generated Li2SO4 enters the liquid phase, that is, most of the lithium element in the calcined powder enters the liquid phase. The first lithium elution rate after acid dissolution treatment is 88% to 92%.

[0067] In this application, the acid dissolution treatment in step (3) includes the following reactions:

[0068] Li2CO3+H2SO4=Li2SO4+CO2↑+H2O

[0069] Me + H₂SO₄ = H₂↑ + MeSO₄;

[0070] MeO + H2SO4 = H2O + MeSO4.

[0071] In some embodiments of this application, step (4) of electrolyzing the solid-liquid mixture includes electrolyzing MeSO4 in the liquid phase of the solid-liquid mixture. In some embodiments of this application, in step (4), the lithium-containing solution includes Li2SO4; in the lithium-containing solution, the mass of Li2SO4 is n1, satisfying n1 > m1, where m1 is the mass of Li2SO4 in the liquid phase of the solid-liquid mixture in step (3). After electrolysis, Li2CO3 in the solid phase will also leach out in the form of Li2SO4. In some embodiments of this application, in step (4), the second lithium elution rate of the lithium-containing solution is ≥98%.

[0072] In this application, when Me is selected from Ni, Co, and Mn (i.e., nickel-cobalt-manganese ternary batteries), the electrolysis of CoSO4 yields products including elemental Co and sulfuric acid; the electrolysis of NiSO4 yields products including elemental Ni and sulfuric acid; and the electrolysis of MnSO4 yields products including sulfuric acid containing MnO2. The proportions of nickel, cobalt, and manganese in MeSO4 are not limited in this application, but are generally similar to the proportions of nickel, cobalt, and manganese in the positive electrode active material. Exemplarily, the electrolysis reaction is carried out in the following manner:

[0073] The electrolytic treatment in step (4) includes the following reactions:

[0074]

[0075] Electrolysis of MeSO4 in the solid-liquid mixture produces sulfuric acid, allowing the remaining small amount of solid phase Li2CO3 to continue reacting with sulfuric acid to form Li2SO4 that can exist in the liquid phase. Therefore, the mass n1 of Li2SO4 in the lithium-containing solution is greater than the mass m1 of Li2SO4 in the liquid phase of the solid-liquid mixture in step (3), thus improving the lithium elution rate. The second lithium elution rate of the lithium-containing solution is ≥98%. This means maximizing the elution rate of Li... + In the liquid phase, nickel, cobalt, and manganese are separated in the solid phase, thus achieving the separation and purification of the two elements, namely Li and Me, where Me is Ni, Co, and Mn.

[0076] In some embodiments of this application, in step (4), the filter residue includes Me-containing powder; the mass percentage of Me-containing powder in the filter residue is w1%; satisfying: w1% > w2%; where w2% is the mass percentage of Me-containing powder in the solid phase of the solid-liquid mixture in step (3). In the above electrolytic treatment, since the Li2CO3 acid in the solid phase dissolves and immerses in the liquid phase, it is equivalent to purifying the solid phase. Therefore, the mass percentage of Me-containing powder in the filter residue w1% is greater than the mass percentage of Me-containing powder in the solid phase of the solid-liquid mixture in step (3) w2%. That is, the sulfuric acid generated by the first electrolysis can react with Li2CO3 in the solid phase, which is equivalent to purifying the solid phase. Therefore, the mass percentage of Me-containing powder in the first filter residue increases.

[0077] In some embodiments of this application, in step (4), electrolysis also yields an anode product and a cathode product; the anode product includes MnO2; the cathode product includes at least one of elemental Ni and elemental Co. Taking a nickel-cobalt-manganese ternary battery as an example, the above electrolysis yields the anode product MnO2 and the cathode products elemental Ni and elemental Co.

[0078] In some embodiments of this application, in step (4), the conditions for the end of electrolysis include: for every 100g of black powder, when the electrolysis capacity C1 in the electrolysis process satisfies Equation 1, the electrolysis ends;

[0079] 10Ah≤C1 (Equation 1)

[0080] By adjusting the electrolysis capacity C1 within the above range, the electrolysis of MeSO4 is achieved, thereby separating the original compounds with MeSO4. 2+ Combined SO4 2- , with Li + This combination improves the elution rate of lithium.

[0081] In some embodiments of this application, in step (4), the conditions for the end of electrolysis include: for every 100g of the black powder, the first lithium elution rate after acid dissolution treatment in step (3) is 88% to 90%, and the electrolysis ends when the electrolysis capacity C1 in the electrolysis process satisfies formula 1-a;

[0082] 11Ah≤C1≤13Ah, formula 1-a.

[0083] In some embodiments of this application, in step (4), the conditions for the end of electrolysis include: for every 100g of the black powder, the first lithium elution rate after acid dissolution treatment in step (3) is 90% to 92%, and the electrolysis ends when the electrolysis capacity C1 in the electrolysis process satisfies formula 1-b;

[0084] 10Ah≤C1≤12Ah (Equation 1-b)

[0085] The Li elution rate during the acid dissolution process is related to the electrolytic capacity C1 of the subsequent electrolysis. In this application, the electrolytic capacity C1 during the electrolysis process can be determined based on the first Li elution rate during the acid dissolution process. For example, when the first lithium elution rate after acid dissolution is high, at 90% to 92%, the MeSO4 content in the liquid phase is low, and the electrolytic capacity C1 required for electrolysis is also low, satisfying Equation 1-b: 10Ah≤C1≤12Ah; when the first lithium elution rate after acid dissolution is low, at 88% to 90%, the MeSO4 content in the liquid phase is high, and the electrolytic capacity C1 required for electrolysis is also high, satisfying Equation 1-a: 11Ah≤C1≤13Ah.

[0086] In some embodiments of this application, the electrolysis voltage U1 is 2.5V to 4.5V, and the temperature T1 is 30℃ to 80℃. For example, the electrolysis voltage U1 can be 2.5V, 3V, 3.5V, 4V, or 4.5V, or any two of the above values; the electrolysis temperature T1 can be 30℃, 40℃, 50℃, 70℃, or 80℃, or any two of the above values. By controlling the electrolysis voltage and temperature within the above ranges, it is beneficial to ensure the full progress of the MeSO4 electrolysis reaction, generating sulfuric acid that can react with Li2CO3, thereby improving the lithium elution rate.

[0087] In some embodiments of this application, in step (1), the pretreatment includes crushing, sieving, and high-temperature treatment. The temperature T4 of the high-temperature treatment is 300°C to 800°C, the time t4 is 0.1h to 10h, and the atmosphere is selected from air or oxygen. For example, the temperature T4 of the high-temperature treatment can be 300°C, 400°C, 500°C, 600°C, 700°C, or 800°C, or any two of the above numbers. For example, the time t4 of the high-temperature treatment can be 0.1h, 1h, 2h, 4h, 6h, 8h, or 10h, or any two of the above numbers. The positive current collector and the positive electrode material layer of the disassembled positive electrode are separated to obtain the positive electrode material. The positive electrode material is crushed and sieved to prepare positive electrode material powder within a certain particle size range. Subsequently, the positive electrode material powder is subjected to high-temperature treatment to remove the conductive agent, electrolyte, and binder, thereby obtaining black powder. This application does not have a particular limitation on the particle size of the positive electrode material powder, as long as it can achieve the purpose of this application.

[0088] Example

[0089] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below. Furthermore, unless otherwise specified, "parts" and "%" are quality standards.

[0090] Test methods and equipment:

[0091] Calculation of lithium elution rate:

[0092] The mass percentage (%) of Li in black powder, the mass concentration (mg / kg) of Li in the liquid phase of the solid-liquid mixture, and the mass concentration (mg / kg) of Li in the filter residue were determined by ICP.

[0093] The Li content (in g) in the solid phase of a solid-liquid mixture = the Li mass concentration (in mg / kg) in the solid phase of the solid-liquid mixture × 10 -6 × The mass of the solid phase in the solid-liquid mixture (in grams).

[0094] Li content in filter residue (in g) = Li mass concentration in filter residue (in mg / kg) × 10 -6 × Mass of filter residue (in g).

[0095] Li content in black powder (in g) = mass percentage of Li in black powder × mass of black powder (in g).

[0096] First lithium elution rate = (1 - Li content in the solid phase of the solid-liquid mixture / Li content in the black powder) × 100%.

[0097] Second lithium elution rate = (1 - Li content in filter residue / Li content in black powder) × 100%.

[0098] Filter residue purity test:

[0099] The content of elemental Me and / or MeO in the filter residue was determined by ICP, in mg / kg.

[0100] Filter residue purity = content of elemental substances and / or MeO in the filter residue × 10 -6 ×100%.

[0101] Preparation of black powder:

[0102] Used ternary 811 lithium-ion batteries (LiNi) 0.8 Co 0.1 Mn 0.1 The positive electrode material layer obtained from the disassembly (O2) is crushed and sieved to obtain positive electrode material powder. The positive electrode material powder is then pretreated in a rotary kiln at T4 = 550℃ by introducing air to remove residual conductive agent, electrolyte, and binder. The pretreatment time is t4 = 2 hours. The powder is then passed through a 150-mesh sieve to obtain black powder A, where the lithium content is calculated to be 6.9 wt%.

[0103] Used ternary 111 lithium-ion batteries (LiNi) 1 / 3 Co 1 / 3 Mn 1 / 3 The positive electrode material layer obtained from the disassembly (O2) is crushed and sieved to obtain positive electrode material powder. The positive electrode material powder is then pretreated in a rotary kiln at T4 = 550℃ by introducing air to remove residual conductive agent, electrolyte, and binder. The pretreatment time is t4 = 2 hours. The powder is then passed through a 150-mesh sieve to obtain black powder B, where the lithium content of black powder B is calculated to be 7.1 wt%.

[0104] Example 1

[0105] Figure 1 The experimental flowchart for Example 1 is shown below, with the specific steps as follows:

[0106] 100g of black powder A, mixed with 10g of carbon, was used for reduction roasting. Nitrogen gas was first introduced to purge other gases from the tube, then heating was started. The tube furnace temperature T3 was set at 700℃ for a duration t1 of 90 minutes, yielding roasted powder. After cooling, the roasted powder was removed and acid-dissolved using 111.3ml of 4.8mol / L sulfuric acid. The molar ratio of Li in the roasted powder to H in the sulfuric acid was approximately 1:1.07, resulting in a solid-liquid mixture with approximately 51g of solid phase. At this point, the first lithium elution rate was 90.6%. After acid dissolution, electrolysis was performed at a constant voltage of U1 = 3.5V, a temperature T1 of 50℃, and an electrolysis capacity C1 of 11Ah. After electrolysis, the mixture was filtered. The filter residue was approximately 50g of nickel-cobalt-manganese (containing Co, Ni, and MnO) powder with a purity of 98.2%. The filtrate was a lithium-containing solution with a second lithium elution rate of 98%.

[0107] Table 1. Mass concentration of each element in the solid phase of the solid-liquid mixture.

[0108] element Mass concentration of each element in the solid phase of a solid-liquid mixture (mg / kg) Ni 745272.32 Co 97566.61 Mn 27721.66 Li 12702.91 First lithium elution rate: 90.6%

[0109] Table 2. Mass concentration of various elements in the powder and filter residue after electrolysis.

[0110]

[0111] Example 2

[0112] 100g of black powder A, mixed with 12g of carbon, was used for reduction roasting. Nitrogen gas was first introduced to purge other gases from the tube, then heating was started. The tube furnace temperature T3 was set at 600℃ for a duration t1 of 150min, yielding roasted powder. After cooling, the roasted powder was removed and acid-dissolved using 116.6ml of 4.8mol / L sulfuric acid. The molar ratio of Li in the roasted powder to H in the sulfuric acid was approximately 1:1.1, resulting in a first lithium elution rate of 92%. After acid dissolution, electrolysis was performed at a constant voltage of U1 = 3.8V, a temperature T1 of 60℃, and an electrolysis capacity C1 of 10.2Ah. After electrolysis, the mixture was filtered. The filter residue was nickel-cobalt-manganese (Co, Ni, MnO) powder with a purity of 98.7%, and the filtrate was a lithium-containing solution with a second lithium elution rate of 98.5%.

[0113] Example 3

[0114] 100g of black powder A, mixed with 15g of carbon, was used for reduction roasting. Nitrogen gas was first introduced to purge other gases from the tube, then heating was started. The tube furnace temperature T3 was set at 550℃ for a duration t1 of 180min, yielding roasted powder. After cooling, the roasted powder was removed and acid-dissolved using 112.4ml of 4.8mol / L sulfuric acid. The molar ratio of Li in the roasted powder to H in the sulfuric acid was approximately 1:1.08, resulting in a first lithium elution rate of 91%. After acid dissolution, electrolysis was performed using a constant voltage electrolysis method (U1 = 3V), a temperature T1 of 50℃, and an electrolysis capacity C1 of 10.8Ah. After electrolysis, the mixture was filtered. The filter residue was nickel-cobalt-manganese (Co, Ni, MnO) powder with a purity of 98.3%, and the filtrate was a lithium-containing solution with a second lithium elution rate of 98.4%.

[0115] Example 4

[0116] 100g of black powder A, mixed with 10g of carbon, was used for reduction roasting. Nitrogen gas was first introduced to purge other gases from the tube, then heating was started. The tube furnace temperature T3 was set at 680℃ for a duration t1 of 120min, yielding roasted powder. After cooling, the roasted powder was removed and acid-dissolved using 106.2ml of 4.8mol / L sulfuric acid. The molar ratio of Li in the roasted powder to H in the sulfuric acid was approximately 1:1.02, resulting in a first lithium elution rate of 89.1%. After acid dissolution, electrolysis was performed at a constant voltage of U1 = 3.5V, a temperature T1 of 50℃, and an electrolysis capacity C1 of 12.1Ah. After electrolysis, the mixture was filtered. The filter residue was nickel-cobalt-manganese (containing Co, Ni, and MnO) powder with a purity of 98.5%, and the filtrate was a lithium-containing solution. The second lithium elution rate of the lithium-containing solution was 98.2%.

[0117] Example 5

[0118] 100g of black powder A, mixed with 10g of carbon, was used for reduction roasting. Nitrogen gas was first introduced to purge other gases from the tube, then heating was started. The tube furnace temperature T3 was set at 700℃, and the duration t1 was 90min, yielding roasted powder. After cooling, the roasted powder was removed and acid-dissolved using 137.8ml of 4.8mol / L sulfuric acid. The molar ratio of Li in the roasted powder to H in the sulfuric acid was approximately 1:1.3, resulting in a first lithium elution rate of 95%. After acid dissolution, electrolysis was performed at a constant voltage of U1 = 3.5V, a temperature T1 of 50℃, and an electrolysis capacity C1 of 15Ah. After electrolysis, the mixture was filtered. The filter residue was nickel-cobalt-manganese (containing Co, Ni, and MnO) powder with a purity of 99.3%, and the filtrate was a lithium-containing solution with a second lithium elution rate of 99.3%.

[0119] In this embodiment, due to the addition of more acid, more nickel, cobalt, and manganese elements were washed off after acid washing (i.e., nickel, cobalt, and manganese elements entered the liquid phase). Compared with Example 1, the content of nickel, cobalt, and manganese elements in the liquid phase was about 2 to 3 times, which reduced the purity of lithium sulfate in the lithium-containing solution, which was not conducive to the subsequent purification of lithium sulfate, and the recovery rate of nickel, cobalt, and manganese was low.

[0120] Example 6

[0121] 100g of black powder A, mixed with 10g of carbon, was used for reduction roasting. Nitrogen gas was first introduced to purge other gases from the tube, then heating was started. The tube furnace temperature T3 was set at 700℃, and the duration t1 was 90min, yielding roasted powder. After cooling, the roasted powder was removed and acid-dissolved using 103.9ml of 4.8mol / L sulfuric acid. The molar ratio of Li in the roasted powder to H in the sulfuric acid was approximately 1:0.98, resulting in a first lithium elution rate of 85%. After acid dissolution, electrolysis was performed at a constant voltage of U1 = 3.5V, a temperature T1 of 50℃, and an electrolysis capacity C1 of 13.8Ah. After electrolysis, the mixture was filtered. The filter residue was nickel-cobalt-manganese (containing Co, Ni, and MnO) powder with a purity of 97.6%. The filtrate was a lithium-containing solution, with a second lithium elution rate of 94.9%.

[0122] Example 7

[0123] 100g of black powder B, mixed with 10g of carbon, was used for reduction roasting. Nitrogen gas was first introduced to purge other gases from the tube, then heating was started. The tube furnace temperature T3 was set at 700℃ for a duration t1 of 90 minutes, yielding roasted powder. After cooling, the roasted powder was removed and acid-dissolved using 111.3ml of 4.8mol / L sulfuric acid. The molar ratio of Li in the roasted powder to H in the sulfuric acid was approximately 1:1.04, resulting in a first lithium elution rate of 91.1%. After acid dissolution, electrolysis was performed at a constant voltage of U1 = 3.5V, a temperature T1 of 50℃, and an electrolysis capacity C1 of 11.3Ah. After electrolysis, the mixture was filtered. The filter residue was nickel-cobalt-manganese (containing Co, Ni, and MnO) powder with a purity of 98.7%, and the filtrate was a lithium-containing solution. The second lithium elution rate of the lithium-containing solution was 98.1%.

[0124] Comparative Example 1

[0125] 100g of black powder mixed with 10g of carbon was used for reduction roasting. Nitrogen gas was first introduced to purge other gases from the tube, then heating was started. The tube furnace temperature T3 was set at 700℃, and the duration t1 was 90min, yielding roasted powder. After cooling, the roasted powder was removed and acid-dissolved using 99ml of 4.8mol / L sulfuric acid. The molar ratio of Li in the roasted powder to H in the sulfuric acid was approximately 1:0.95, resulting in a first lithium elution rate of 80%. After acid dissolution, electrolysis was performed using a constant voltage electrolysis method (U1 = 3.5V), a temperature T1 of 50℃, and an electrolysis capacity C1 of 14Ah. After electrolysis, the mixture was filtered. The filter residue was nickel-cobalt-manganese (containing Co, Ni, and MnO) powder with a purity of 85%. The filtrate was a lithium-containing solution, with a second lithium elution rate of 84.1%. The nickel-cobalt-manganese powder contained numerous impurities.

[0126] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for extracting lithium from waste batteries, comprising the following steps: (1) Pretreatment: Obtain waste ternary cathode material, and pretreat the waste ternary cathode material to obtain black powder; (2) Reduction roasting treatment: The black powder is reduced and roasted to obtain roasted powder; (3) Acid dissolution treatment: The calcined powder is subjected to acid dissolution reaction with sulfuric acid solution to obtain a solid-liquid mixture; the molar ratio of Li element in the calcined powder to H element in the sulfuric acid solution is 1:(0.98~1.3); (4) Electrolysis treatment: The solid-liquid mixture is electrolyzed, and after the electrolysis is completed, the residue and lithium-containing solution are obtained by filtration.

2. The method according to claim 1, wherein, In step (2), the reduction roasting of the black powder includes: The black powder is calcined in the presence of a reducing agent, wherein the reducing agent includes C and / or CO; and, In step (2), the calcined powder obtained includes Li2CO3 and Me-containing powder; The Me-containing powder includes elemental Me and / or MeO; The Me is selected from at least one of the elements Ni, Co, and Mn.

3. The method according to claim 1, wherein, In step (3), the molar ratio of Li element in the calcined powder to H element in the sulfuric acid solution is 1:(1.01~1.1); Preferably, in step (3), the solid-liquid mixture comprises a liquid phase and a solid phase, wherein the liquid phase contains Li2SO4 and MeSO4, and the solid phase contains Li2CO3 and Me-containing powder.

4. The method according to claim 3, wherein, In step (3), in the liquid phase, the molar amount of Li in Li2SO4 is p1, and the molar amount of Me in MeSO4 is p2, satisfying p1 > p2; in the solid phase, the molar amount of Me in the Me-containing powder is p3, and the molar amount of Li in Li2CO3 is p4, satisfying p3 > p4. Preferably, in step (3), the first lithium elution rate after acid dissolution treatment is 88% to 92%.

5. The method according to claim 3, wherein, In step (4), the electrolysis of the solid-liquid mixture includes: The MeSO4 in the liquid phase of the solid-liquid mixture is electrolyzed.

6. The method according to claim 5, wherein, In step (4), the conditions for the end of electrolysis include: for every 100g of the black powder, when the electrolysis capacity C1 in the electrolysis process satisfies Equation 1, the electrolysis ends; 10Ah≤C1 (Equation 1) 7. The method according to claim 6, wherein, In step (4), the conditions for the end of electrolysis include: for every 100g of the black powder, the first lithium elution rate after the acid dissolution treatment in step (3) is 88% to 90%, and the electrolysis capacity C1 in the electrolysis process satisfies formula 1-a, when the electrolysis ends. 11Ah≤C1≤13Ah, formula 1-a.

8. The method according to claim 6, wherein, In step (4), the conditions for the end of electrolysis include: for every 100g of the black powder, the first lithium elution rate after the acid dissolution treatment in step (3) is 90% to 92%, and the electrolysis is ended when the electrolysis capacity C1 in the electrolysis process satisfies formula 1-b; 10Ah≤C1≤12Ah (Equation 1-b) 9. The method according to claim 5, wherein, In step (4), the lithium-containing solution includes Li2SO4; in the lithium-containing solution, the mass of the Li2SO4 is n1, satisfying n1 > m1, where m1 is the mass of the Li2SO4 in the liquid phase of the solid-liquid mixture in step (3); Preferably, in step (4), the second lithium elution rate of the lithium-containing solution is ≥98%; Preferably, in step (4), the filter residue includes the Me-containing powder; the mass percentage of the Me-containing powder in the filter residue is w1%; satisfying: w1% > w2%; wherein, w2% is the mass percentage of the Me-containing powder in the solid phase of the solid-liquid mixture in step (3); Preferably, in step (4), the electrolysis also yields an anode product and a cathode product; the anode product includes MnO2; the cathode product includes at least one of elemental Ni and elemental Co.

10. The method according to claim 1, wherein, At least one of the following conditions must be met: Condition a: In step (2), the amount of the reducing substance used is 8 wt% to 15 wt% of the black powder; Condition b: In step (2), the reduction calcination temperature T3 is 550℃~700℃, and the calcination time t3 is 1h~3h; Condition c: In step (3), the concentration of the sulfuric acid solution is 1 mol / L to 5 mol / L; Condition d: In step (4), the voltage U1 of the electrolysis is 2.5V to 4.5V and the temperature T1 is 30℃ to 80℃.

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