A method of electrochemically assisted green leaching of retired lithium-ion batteries

Abstract

The application discloses a method for electrochemically assisted green leaching of retired lithium ion batteries, and belongs to the technical field of key metal recycling of retired lithium batteries and retired battery recycling, and specifically comprises the following steps: disassembling a retired ternary lithium battery, taking out a positive electrode material, cleaning, drying and grinding the positive electrode material, and placing the positive electrode material in a reaction container together with a weak acid solution to form a leaching system; installing an inert electrode in the reaction container, connecting an external direct current power supply, gradually adjusting the voltage according to the potential requirement of metal ion dissolution, and making nickel ions, cobalt ions and manganese ions be leached respectively to obtain a multi-metallic noble liquid; adding a precipitant to the obtained solution to perform precipitation, generating lithium carbonate precipitate, and recycling the lithium carbonate precipitate through filtration, washing and drying to obtain a high-purity lithium compound. The application not only reduces the use of strong acid and complex chemical reagents, significantly reduces the complexity of waste liquid treatment, and realizes efficient recycling of target metals through step-by-step control of the metal dissolution process.

Description

Technical Field

[0001] This invention belongs to the field of key metal recycling and utilization of retired lithium batteries and the field of retired battery recycling technology, specifically involving an electrochemical-assisted green leaching method for retired lithium-ion batteries. Background Technology

[0002] With the rapid development of the electric vehicle and electronic product markets, the number of retired ternary lithium batteries has increased dramatically, making efficient recycling a crucial issue for the industry. Retired lithium-ion batteries contain various key metals such as nickel, cobalt, lithium, and manganese. Nickel and cobalt, in particular, are precious and scarce metal resources with high recycling value.

[0003] Current recycling methods for retired ternary lithium batteries mostly employ acidic chemical leaching technology. This involves applying an electric field to the acidic leaching system and using potential control to achieve the gradual and selective dissolution of metals such as nickel, cobalt, and manganese. Under specific voltages, electrochemical leaching can effectively control the preferential precipitation of specific metal ions, reduce the co-dissolution of impurities, and significantly simplify subsequent separation and purification processes. Electrochemical-assisted leaching technology aligns with the modern trend towards green and sustainable development in retired battery recycling and is gradually becoming a research hotspot in the field of retired lithium battery recycling.

[0004] Patent CN119040659A proposes a lithium leaching process based on the synergistic effect of acid and oxidant, achieving efficient lithium recovery through multiple leaching steps. However, this process relies on a strong acid system (such as sulfuric acid) and requires multi-stage chemical impurity removal, potentially introducing equipment corrosion risks and complex wastewater treatment. This invention innovatively uses a weakly acidic citric acid solution to replace the traditional strong acid system, combined with electrochemical stepwise potential control, to achieve selective stepwise dissolution of nickel, cobalt, and manganese under ambient temperature conditions. Through precise potential control and the synergistic effect of the weak acid environment, this invention eliminates reliance on complex reagents, significantly reduces equipment corrosion and wastewater toxicity, and simplifies subsequent separation processes. Furthermore, lithium resources are efficiently recovered through sodium carbonate precipitation, reducing energy consumption by more than 30% while maintaining environmental friendliness and economic efficiency, providing a more competitive solution for the green industrial recycling of retired lithium batteries. Summary of the Invention

[0005] To address the problems existing in current technologies for recycling retired power batteries, this invention relates to an electrochemically assisted green leaching method for retired lithium-ion batteries, aiming to solve the problems of environmental pollution, high energy consumption, and poor selectivity in the current metal recycling process of ternary lithium batteries. This method, based on electrochemically assisted technology, achieves selective leaching of metals such as nickel, cobalt, and manganese from the cathode material of retired ternary lithium batteries by applying an appropriate potential in a weakly acidic environment. This invention not only reduces the use of strong acids and complex chemical reagents, significantly reducing the complexity of wastewater treatment, but also achieves efficient recovery of target metals through stepwise control of the metal leaching process.

[0006] To achieve the above objectives, the present invention provides an electrochemically assisted green leaching method for retired lithium-ion batteries, specifically comprising the following steps:

[0007] (1) Pretreatment: Disassemble the retired ternary lithium battery, take out the positive electrode material, clean and dry it, grind it to D50 = 2μm ~ 5μm, and place it in the reaction vessel;

[0008] (2) Preparation of leaching solution: Place a weak acid solution as the leaching solution in the reaction vessel to form a leaching system;

[0009] (3) Electrode installation and electric field setting: Install inert electrodes in the reaction vessel and connect an external DC power supply. Gradually adjust the voltage according to the potential requirements for metal ion dissolution.

[0010] (4) Nickel ion leaching: Adjust the power supply potential to dissolve nickel ions from the leaching system and generate a leachate containing nickel ions; during the leaching process, periodically sample and analyze the ion concentration in the leachate. When the ion concentration changes tend to be stable, the leaching is over.

[0011] (5) Cobalt ion dissolution: After the nickel dissolution is completed, the potential is adjusted to dissolve cobalt ions from the leaching system, generating a leachate containing cobalt ions.

[0012] (6) Manganese ion dissolution: After the cobalt dissolution is completed, the potential is adjusted to dissolve the manganese ions from the leaching system, generating a leachate containing manganese ions. The potential is maintained to ensure that the manganese ions are completely dissolved, and a multi-metal precious solution is obtained.

[0013] (7) Precipitation of lithium: Add a precipitant to the solution obtained in step (6) to precipitate lithium carbonate, which is then recovered by filtration, washing and drying to obtain high-purity lithium compounds.

[0014] in:

[0015] In step (2), the weak acid solution is a citric acid or malic acid solution with a concentration of 0.2 mol / L to 0.5 mol / L.

[0016] In step (3), the material of the inert electrode is selected from platinum, titanium, and graphite.

[0017] In step (3), the initial voltage of the DC power supply is 0.5V to 3V.

[0018] In step (4), during the nickel ion leaching process, the power supply potential is 0.6V to 1.0V, and the nickel leaching rate is 90% to 98%.

[0019] In step (5), during the cobalt ion leaching process, the power supply potential is 1.2V to 1.6V, and the cobalt leaching rate is 85% to 95%.

[0020] In step (6), during the manganese ion leaching process, the power supply potential is 1.8V to 2.2V, and the manganese leaching rate is 80% to 95%.

[0021] During the leaching process of nickel, cobalt, and manganese ions, the ion concentration in the leachate is sampled and analyzed periodically. The leaching process ends when the ion concentration changes tend to stabilize.

[0022] In step (7), the precipitant is a sodium carbonate solution with a concentration of 0.05 mol / L to 0.2 mol / L, and the recovery rate of lithium obtained is 95% to 98%.

[0023] Compared with existing comprehensive recycling processes for retired power batteries, the features and advantages of this invention are as follows:

[0024] 1. This invention utilizes an electric current applied to a weakly acidic solution to rapidly dissolve and transfer metal ions into the solution through electrochemical action. Compared to traditional high-temperature roasting or wet acid leaching methods, this invention significantly reduces energy consumption because the electrochemical reaction can be carried out at room temperature or low temperature, avoiding the energy consumption and equipment requirements of high-temperature heating processes. In particular, electrochemical-assisted leaching can be carried out efficiently under relatively low current and voltage conditions, reducing the energy waste caused by high-temperature roasting and long reaction times in traditional methods.

[0025] 2. The solution provided by this invention reduces the generation of acidic waste liquid during the leaching process, and the waste liquid has a relatively simple composition, making it easy to treat. With proper treatment, the waste liquid can be utilized as a resource, reducing the risk of secondary pollution and lowering the cost of waste liquid treatment, thus achieving good environmental and economic benefits.

[0026] 3. This invention enables efficient and selective dissolution of metals such as lithium, nickel, cobalt, and manganese in a weakly acidic environment. Electrochemical action promotes metal reduction and redox reactions, increasing the dissolution rate and selectivity of metal ions and reducing the problem of metal ion co-dissolution. This makes the separation of different metals more efficient, especially in multi-metal mixed solutions. By adjusting the current density and voltage, stepwise metal recovery can be achieved, ensuring a higher metal recovery rate. Attached Figure Description

[0027] Figure 1 A process flow diagram of an electrochemically assisted green leaching method for retired lithium-ion batteries according to the present invention. Detailed Implementation

[0028] The technical solutions in the implementation of this patent will be clearly and completely described below with reference to the embodiments and accompanying drawings. It should be noted that the embodiments described in this invention are only for further explanation and illustration, and not for limiting their scope of application. Based on this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this patent.

[0029] Example 1

[0030] In this embodiment, the retired ternary lithium battery comes from a technology company in Guangdong Province. Its Li content is 3.59%, Co content is 4.59%, Mn content is 9.58%, Ni content is 17.15%, and C content is 40.20%, with C mainly existing in the graphite state.

[0031] An electrochemically assisted green leaching method for retired lithium-ion batteries, the process flow diagram of which is shown below. Figure 1 As shown, the specific steps include:

[0032] (1) Pretreatment: The retired ternary lithium battery is disassembled, the positive electrode material is taken out, cleaned and dried, and then ground to D50 = 2μm~5μm to increase the contact area between the metal and the leachate and promote the subsequent dissolution of the metal. The obtained positive electrode material particles are placed in a reaction vessel for later use.

[0033] (2) Preparation of leaching solution: A 0.3 mol / L citric acid solution is used as the leaching solution and placed in the reaction vessel to provide a suitable acidic environment to form the leaching system.

[0034] (3) Electrode installation and electric field setting: Install platinum electrodes in the reaction vessel to ensure the stability of the electrodes in a weakly acidic environment. Connect an external DC power supply and set the initial voltage to 2V. Adjust the voltage gradually according to the potential requirements of metal ion dissolution.

[0035] (4) Nickel ion leaching: Adjust the power supply potential to 0.8V to dissolve nickel ions from the leaching system and generate a leaching solution containing nickel ions; during the leaching process, periodically sample and analyze the nickel ion concentration in the leaching solution. When the nickel ion concentration changes to a stable level, the leaching is complete.

[0036] (5) Cobalt ion leaching: After nickel leaching is completed, the potential is adjusted to 1.4V to allow cobalt ions to dissolve from the leaching system and generate a leachate containing cobalt ions. During the leaching process, the concentration of cobalt ions in the leachate is sampled and analyzed periodically. The leaching is considered complete when the concentration of cobalt ions tends to stabilize.

[0037] (6) Manganese ion leaching: After the cobalt leaching is completed, the potential is adjusted to 2.0V to allow manganese ions to dissolve from the leaching system and generate a leachate containing manganese ions. This potential is maintained to ensure that the manganese ions are completely dissolved and a multi-metallic precious solution is obtained. During the leaching process, the concentration of manganese ions in the leachate is sampled and analyzed periodically. When the change in the concentration of manganese ions tends to be stable, the leaching is considered complete.

[0038] (7) Precipitation of lithium: Add a sodium carbonate solution with a concentration of 0.1 mol / L to the solution obtained in step (6) to precipitate lithium carbonate, which is then recovered by filtration, washing and drying to obtain high-purity lithium compounds.

[0039] In this embodiment, the leaching rates of Ni, Co, and Mn in the transition metal leaching solutions were 95.78%, 90.36%, and 87.25%, respectively. The lithium recovery rate obtained by the sodium carbonate precipitation method was 97.16%, which meets the requirements for battery-grade lithium materials.

[0040] Example 2

[0041] In this embodiment, the retired ternary lithium battery comes from a technology company in Hunan Province. Its Li content is 3.87%, Co content is 3.16%, Mn content is 5.22%, Ni content is 22.47%, and C content is 35.36%, with C mainly existing in the graphite state.

[0042] An electrochemically assisted green leaching method for retired lithium-ion batteries specifically includes the following steps:

[0043] (1) Pretreatment: The retired ternary lithium battery is disassembled, the positive electrode material is taken out, cleaned and dried, and then ground to D50 = 2μm~5μm to increase the contact area between the metal and the leachate and promote the subsequent dissolution of the metal. The obtained positive electrode material particles are placed in a reaction vessel for later use.

[0044] (2) Preparation of leaching solution: A 0.4 mol / L citric acid solution is placed in a reaction vessel to provide a suitable acidic environment and form a leaching system.

[0045] (3) Electrode installation and electric field setting: Install graphite electrodes in the reaction vessel to ensure the stability of the electrodes in a weakly acidic environment. Connect an external DC power supply and set the initial voltage to 2V. Adjust the voltage gradually according to the potential requirements of metal ion dissolution.

[0046] (4) Nickel ion leaching: Adjust the power supply potential to 0.8V to dissolve nickel ions from the leaching system and generate a leaching solution containing nickel ions; during the leaching process, periodically sample and analyze the nickel ion concentration in the leaching solution. When the nickel ion concentration changes to a stable level, the leaching is complete.

[0047] (5) Cobalt ion leaching: After nickel leaching is completed, the potential is adjusted to 1.4V to allow cobalt ions to dissolve from the leaching system and generate a leachate containing cobalt ions. During the leaching process, the concentration of cobalt ions in the leachate is sampled and analyzed periodically. The leaching is considered complete when the concentration of cobalt ions tends to stabilize.

[0048] (6) Manganese ion leaching: After the cobalt leaching is completed, the potential is adjusted to 2.0V to allow manganese ions to dissolve from the leaching system and generate a leachate containing manganese ions. This potential is maintained to ensure that the manganese ions are completely dissolved and a multi-metallic precious solution is obtained. During the leaching process, the concentration of manganese ions in the leachate is sampled and analyzed periodically. When the change in the concentration of manganese ions tends to be stable, the leaching is considered complete.

[0049] (7) Precipitation of lithium: Add a sodium carbonate solution with a concentration of 0.1 mol / L to the solution obtained in step (6) to precipitate lithium carbonate, which is then recovered by filtration, washing and drying to obtain high-purity lithium compounds.

[0050] In this embodiment, the leaching rates of Ni, Co, and Mn in the transition metal leaching solutions were 96.97%, 89.43%, and 85.54%, respectively. The lithium recovery rate obtained by the sodium carbonate precipitation method was 97.49%, which meets the requirements for battery-grade lithium materials.

[0051] Example 3

[0052] In this embodiment, the retired ternary lithium battery comes from a certain technology company. Its Li content is 4.56%, Co content is 3.25%, Mn content is 4.59%, Ni content is 22.23%, and C content is 38.09%. C mainly exists in the graphite state.

[0053] An electrochemically assisted green leaching method for retired lithium-ion batteries specifically includes the following steps:

[0054] (1) Pretreatment: The retired ternary lithium battery is disassembled, the positive electrode material is taken out, cleaned and dried, and then ground to D50 = 2μm~5μm to increase the contact area between the metal and the leachate and promote the subsequent dissolution of the metal. The obtained positive electrode material particles are placed in a reaction vessel for later use.

[0055] (2) Preparation of leaching solution: A 0.5 mol / L malic acid solution is placed in a reaction vessel to provide a suitable acidic environment and form a leaching system.

[0056] (3) Electrode installation and electric field setting: Install titanium electrodes in the reaction vessel to ensure the stability of the electrodes in a weakly acidic environment. Connect an external DC power supply and set the initial voltage to 2.5V. Adjust the voltage gradually according to the potential requirements of metal ion dissolution.

[0057] (4) Nickel ion leaching: Adjust the power supply potential to 0.8V to dissolve nickel ions from the leaching system and generate a leaching solution containing nickel ions; during the leaching process, periodically sample and analyze the nickel ion concentration in the leaching solution. When the nickel ion concentration changes to a stable level, the leaching is complete.

[0058] (5) Cobalt ion leaching: After nickel leaching is completed, the potential is adjusted to 1.5V to allow cobalt ions to dissolve from the leaching system and generate a leachate containing cobalt ions. During the leaching process, the concentration of cobalt ions in the leachate is sampled and analyzed periodically. The leaching is considered complete when the concentration of cobalt ions tends to stabilize.

[0059] (6) Manganese ion leaching: After the cobalt leaching is completed, the potential is adjusted to 2.1V to allow manganese ions to dissolve from the leaching system and generate a leachate containing manganese ions. This potential is maintained to ensure that the manganese ions are completely dissolved and a multi-metallic precious solution is obtained. During the leaching process, the concentration of manganese ions in the leachate is sampled and analyzed periodically. When the change in the concentration of manganese ions tends to be stable, the leaching is considered to be over.

[0060] (7) Precipitation of lithium: Add a sodium carbonate solution with a concentration of 0.1 mol / L to the solution obtained in step (6) to precipitate lithium carbonate, which is then recovered by filtration, washing and drying to obtain high-purity lithium compounds.

[0061] In this embodiment, the leaching rates of Ni, Co, and Mn in the transition metal leaching solutions were 94.49%, 90.28%, and 90.64%, respectively. The lithium recovery rate obtained by the sodium carbonate precipitation method was 96.99%, which meets the requirements for battery-grade lithium materials.

[0062] Example 4

[0063] In this embodiment, the retired ternary lithium battery comes from a certain technology company. Its Li content is 3.89%, Co content is 3.21%, Mn content is 5.17%, Ni content is 20.67%, and C content is 38.61%, with C mainly existing in the graphite state.

[0064] An electrochemically assisted green leaching method for retired lithium-ion batteries specifically includes the following steps:

[0065] (1) Pretreatment: The retired ternary lithium battery is disassembled, the positive electrode material is taken out, cleaned and dried, and then ground to D50 = 2μm~5μm to increase the contact area between the metal and the leachate and promote the subsequent dissolution of the metal. The obtained positive electrode material particles are placed in a reaction vessel for later use.

[0066] (2) Preparation of leaching solution: A 0.3 mol / L citric acid solution is used as the leaching solution and placed in the reaction vessel to provide a suitable acidic environment to form the leaching system.

[0067] (3) Electrode installation and electric field setting: Install graphite electrodes in the reaction vessel to ensure the stability of the electrodes in a weakly acidic environment. Connect an external DC power supply and set the initial voltage to 2.3V. Adjust the voltage gradually according to the potential requirements of metal ion dissolution.

[0068] (4) Nickel ion leaching: Adjust the power supply potential to 0.9V to dissolve nickel ions from the leaching system and generate a leaching solution containing nickel ions; during the leaching process, periodically sample and analyze the nickel ion concentration in the leaching solution. When the nickel ion concentration changes to a stable level, the leaching is complete.

[0069] (5) Cobalt ion leaching: After nickel leaching is completed, the potential is adjusted to 1.6V to allow cobalt ions to dissolve from the leaching system and generate a leachate containing cobalt ions. During the leaching process, the concentration of cobalt ions in the leachate is sampled and analyzed periodically. The leaching is considered complete when the concentration of cobalt ions tends to stabilize.

[0070] (6) Manganese ion leaching: After the cobalt leaching is completed, the potential is adjusted to 2.0V to allow manganese ions to dissolve from the leaching system and generate a leachate containing manganese ions. This potential is maintained to ensure that the manganese ions are completely dissolved and a multi-metallic precious solution is obtained. During the leaching process, the concentration of manganese ions in the leachate is sampled and analyzed periodically. When the change in the concentration of manganese ions tends to be stable, the leaching is considered complete.

[0071] (7) Precipitation of lithium: Add a sodium carbonate solution with a concentration of 0.1 mol / L to the solution obtained in step (6) to precipitate lithium carbonate, which is then recovered by filtration, washing and drying to obtain high-purity lithium compounds.

[0072] In this embodiment, the leaching rates of Ni, Co, and Mn in the transition metal leaching solutions were 92.95%, 87.79%, and 84.39%, respectively. The lithium recovery rate obtained by the sodium carbonate precipitation method was 96.41%, which meets the requirements for battery-grade lithium materials.

[0073] Example 5

[0074] In this embodiment, the retired ternary lithium battery comes from a certain technology company. Its Li content is 3.74%, Co content is 3.78%, Mn content is 5.67%, Ni content is 20.14%, and C content is 38.47%, with C mainly existing in the graphite state.

[0075] An electrochemically assisted green leaching method for retired lithium-ion batteries specifically includes the following steps:

[0076] (1) Pretreatment: The retired ternary lithium battery is disassembled, the positive electrode material is taken out, cleaned and dried, and then ground to D50 = 2μm~5μm to increase the contact area between the metal and the leachate and promote the subsequent dissolution of the metal. The obtained positive electrode material particles are placed in a reaction vessel for later use.

[0077] (2) Preparation of leaching solution: A 0.3 mol / L citric acid solution is used as the leaching solution and placed in the reaction vessel to provide a suitable acidic environment to form the leaching system.

[0078] (3) Electrode installation and electric field setting: Install platinum electrodes in the reaction vessel to ensure the stability of the electrodes in a weakly acidic environment. Connect an external DC power supply and set the initial voltage to 2.3V. Adjust the voltage gradually according to the potential requirements of metal ion dissolution.

[0079] (4) Nickel ion leaching: Adjust the power supply potential to 0.9V to dissolve nickel ions from the leaching system and generate a leaching solution containing nickel ions; during the leaching process, periodically sample and analyze the nickel ion concentration in the leaching solution. When the nickel ion concentration changes to a stable level, the leaching is complete.

[0080] (5) Cobalt ion leaching: After nickel leaching is completed, the potential is adjusted to 1.6V to allow cobalt ions to dissolve from the leaching system and generate a leachate containing cobalt ions. During the leaching process, the concentration of cobalt ions in the leachate is sampled and analyzed periodically. The leaching is considered complete when the concentration of cobalt ions tends to stabilize.

[0081] (6) Manganese ion leaching: After the cobalt leaching is completed, the potential is adjusted to 2.0V to allow manganese ions to dissolve from the leaching system and generate a leachate containing manganese ions. This potential is maintained to ensure that the manganese ions are completely dissolved and a multi-metallic precious solution is obtained. During the leaching process, the concentration of manganese ions in the leachate is sampled and analyzed periodically. When the change in the concentration of manganese ions tends to be stable, the leaching is considered complete.

[0082] (7) Precipitation of lithium: Add a sodium carbonate solution with a concentration of 0.1 mol / L to the solution obtained in step (6) to precipitate lithium carbonate, which is then recovered by filtration, washing and drying to obtain high-purity lithium compounds.

[0083] In this embodiment, the leaching rates of Ni, Co, and Mn in the transition metal leachate were 96.47%, 87.79%, and 84.39%, respectively. The lithium recovery rate obtained by sodium carbonate precipitation was 97.48%, which meets the requirements for battery-grade lithium materials.

[0084] Example 6

[0085] In this embodiment, the retired ternary lithium battery comes from a certain technology company. Its Li content is 3.94%, Co content is 3.51%, Mn content is 6.49%, Ni content is 21.42%, and C content is 40.21%. C mainly exists in the graphite state.

[0086] An electrochemically assisted green leaching method for retired lithium-ion batteries specifically includes the following steps:

[0087] (1) Pretreatment: The retired ternary lithium battery is disassembled, the positive electrode material is taken out, cleaned and dried, and then ground to D50 = 2μm~5μm to increase the contact area between the metal and the leachate and promote the subsequent dissolution of the metal. The obtained positive electrode material particles are placed in a reaction vessel for later use.

[0088] (2) Preparation of leaching solution: A 0.3 mol / L citric acid solution is used as the leaching solution and placed in the reaction vessel to provide a suitable acidic environment to form the leaching system.

[0089] (3) Electrode installation and electric field setting: Install platinum electrodes in the reaction vessel to ensure the stability of the electrodes in a weakly acidic environment. Connect an external DC power supply and set the initial voltage to 2.3V. Adjust the voltage gradually according to the potential requirements of metal ion dissolution.

[0090] (4) Nickel ion leaching: Adjust the power supply potential to 0.9V to dissolve nickel ions from the leaching system and generate a leaching solution containing nickel ions; during the leaching process, periodically sample and analyze the nickel ion concentration in the leaching solution. When the nickel ion concentration changes to a stable level, the leaching is complete.

[0091] (5) Cobalt ion leaching: After nickel leaching is completed, the potential is adjusted to 1.6V to allow cobalt ions to dissolve from the leaching system and generate a leachate containing cobalt ions. During the leaching process, the concentration of cobalt ions in the leachate is sampled and analyzed periodically. The leaching is considered complete when the concentration of cobalt ions tends to stabilize.

[0092] (6) Manganese ion leaching: After the cobalt leaching is completed, the potential is adjusted to 2.0V to allow manganese ions to dissolve from the leaching system and generate a leachate containing manganese ions. This potential is maintained to ensure that the manganese ions are completely dissolved and a multi-metallic precious solution is obtained. During the leaching process, the concentration of manganese ions in the leachate is sampled and analyzed periodically. When the change in the concentration of manganese ions tends to be stable, the leaching is considered complete.

[0093] (7) Precipitation of lithium: Add a sodium carbonate solution with a concentration of 0.15 mol / L to the solution obtained in step (6) to precipitate lithium carbonate, which is then recovered by filtration, washing and drying to obtain high-purity lithium compounds.

[0094] In this embodiment, the leaching rates of Ni, Co, and Mn in the transition metal leaching solution were 96.76%, 86.99%, and 85.09%, respectively. The lithium recovery rate obtained by the sodium carbonate precipitation method was 96.65%, which meets the requirements for battery-grade lithium materials.

[0095] Comparative Example 1

[0096] In this example, the retired ternary lithium battery came from a technology company in Guangdong. Its Li grade was 3.59%, Co content was 4.59%, Mn content was 9.58%, Ni content was 17.15%, and C content was 40.20%. C mainly existed in the graphite state.

[0097] An electrochemically assisted green leaching method for retired lithium-ion batteries specifically includes the following steps:

[0098] (1) Pretreatment: The retired ternary lithium battery is disassembled, the positive electrode material is taken out, cleaned and dried, and then ground to D50 = 2μm~5μm to increase the contact area between the metal and the leachate and promote the subsequent dissolution of the metal. The obtained positive electrode material particles are placed in a reaction vessel for later use.

[0099] (2) Preparation of leaching solution: Use pure water at 25°C as leaching solution and place it in the reaction vessel to form a leaching system.

[0100] (3) Electrode installation and electric field setup: Platinum electrodes were installed inside the reaction vessel and connected to an external DC power supply. A voltage of 1.0V and a current density of 10mA / cm² were applied. 2 The reaction time is 60 minutes.

[0101] (4) Precipitation of lithium: Add a sodium carbonate solution with a concentration of 0.1 mol / L to the solution after the reaction in step (3) to precipitate lithium carbonate, which is then recovered by filtration, washing and drying to obtain lithium compounds.

[0102] In this comparative example, the leaching rates of nickel (Ni), cobalt (Co), and manganese (Mn) were all less than 5%. The recovery rate of lithium recovered by sodium carbonate precipitation was 15.26%.

[0103] Compared to Example 1, because the solution is pure water and lacks an acidic medium, it is difficult to effectively dissolve metal ions, resulting in an extremely low leaching rate. These conditions are not suitable for industrial-scale recycling.

[0104] Comparative Example 2

[0105] In this example, the retired ternary lithium battery came from a technology company in Guangdong. Its Li grade was 3.59%, Co content was 4.59%, Mn content was 9.58%, Ni content was 17.15%, and C content was 40.20%. C mainly existed in the graphite state.

[0106] A leaching method for retired lithium-ion batteries specifically includes the following steps:

[0107] (1) Pretreatment: The retired ternary lithium battery is disassembled, the positive electrode material is taken out, cleaned and dried, and then ground to D50 = 2μm~5μm to increase the contact area between the metal and the leachate and promote the subsequent dissolution of the metal. The obtained positive electrode material particles are placed in a reaction vessel for later use.

[0108] (2) Preparation of leaching solution: Use a 0.3 mol / L dilute sulfuric acid solution as the leaching solution. The temperature of the dilute sulfuric acid solution is controlled at 25°C. Place it in a reaction vessel to provide a suitable acidic environment and form a leaching system.

[0109] (3) Leaching of transition metal ions: No voltage is applied, and leaching is carried out solely by the acidic solution in step (2), with a reaction time of 60 min.

[0110] (4) Precipitation of lithium: Add a sodium carbonate solution with a concentration of 0.1 mol / L to the solution after the reaction in step (3) to precipitate lithium carbonate, which is then recovered by filtration, washing and drying to obtain lithium compounds.

[0111] In this comparative example, the leaching rates of nickel (Ni), cobalt (Co), and manganese (Mn) were all below 80%. The recovery rate of lithium recovered by sodium carbonate precipitation was 50.26%.

[0112] Compared to Example 1, the leaching rate was reduced due to the lack of electrochemical assistance, especially the leaching rates of nickel and cobalt were not ideal.

[0113] Comparative Example 3

[0114] In this example, the retired ternary lithium battery came from a certain technology company. Its Li grade was 4.56%, Co content was 3.25%, Mn content was 4.59%, Ni content was 22.23%, and C content was 38.09%. C mainly existed in the graphite state.

[0115] An electrochemically assisted green leaching method for retired lithium-ion batteries specifically includes the following steps:

[0116] (1) Pretreatment: The retired ternary lithium battery is disassembled, the positive electrode material is taken out, cleaned and dried, and then ground to D50 = 2μm~5μm to increase the contact area between the metal and the leachate and promote the subsequent dissolution of the metal. The obtained positive electrode material particles are placed in a reaction vessel for later use.

[0117] (2) Preparation of leaching solution: A 0.5 mol / L malic acid solution is placed in a reaction vessel to provide a suitable acidic environment and form a leaching system.

[0118] (3) Electrode installation and electric field setup: Install titanium electrodes inside the reaction vessel to ensure their stability in an acidic environment. Connect an external DC power supply and set the high voltage to 1.5V and the current density to 20mA / cm². 2 The reaction time is 60 minutes.

[0119] (4) Precipitation of lithium: Add a sodium carbonate solution with a concentration of 0.1 mol / L to the solution after the reaction in step (3) to precipitate lithium carbonate, which is then recovered by filtration, washing and drying to obtain lithium compounds.

[0120] In this comparative example, the leaching rates of nickel (Ni), cobalt (Co), and manganese (Mn) were 80% and 70%, respectively. The recovery rate of lithium recovered by sodium carbonate precipitation was 69.36%.

[0121] Compared to Example 3, the leaching rate was lower due to the lack of electrochemical assistance, especially for nickel and cobalt. High-voltage electrochemical assistance significantly improved the leaching efficiency of metal ions, particularly nickel, cobalt, and manganese, achieving almost complete leaching.

Claims

1. A method for electrochemically assisted green leaching of retired lithium-ion batteries, characterized in that, Specifically, the following steps are included: (1) Pretreatment: Disassemble the retired ternary lithium battery, take out the positive electrode material, clean and dry it, grind it to D50 = 2μm ~ 5μm, and place it in the reaction vessel; (2) Preparation of leaching solution: Place a weak acid solution as the leaching solution in the reaction vessel to form a leaching system; (3) Electrode installation and electric field setting: Install inert electrodes in the reaction vessel and connect an external DC power supply. Gradually adjust the voltage according to the potential requirements for metal ion dissolution. (4) Nickel ion leaching: Adjust the power supply potential to dissolve nickel ions from the leaching system and generate a leachate containing nickel ions; during the leaching process, periodically sample and analyze the ion concentration in the leachate. When the ion concentration changes tend to be stable, the leaching is over. (5) Cobalt ion dissolution: After the nickel dissolution is completed, the potential is adjusted to dissolve cobalt ions from the leaching system, generating a leachate containing cobalt ions. (6) Manganese ion dissolution: After the cobalt dissolution is completed, the potential is adjusted to dissolve the manganese ions from the leaching system, generating a leachate containing manganese ions. The potential is maintained to ensure that the manganese ions are completely dissolved, and a multi-metal precious solution is obtained. (7) Precipitation of lithium: Add a precipitant to the solution obtained in step (6) to precipitate lithium carbonate, which is then recovered by filtration, washing and drying to obtain high-purity lithium compounds.

2. The method for electrochemically assisted green leaching of retired lithium-ion batteries according to claim 1, characterized in that, In step (2), the weak acid solution is a citric acid or malic acid solution with a concentration of 0.2 mol / L to 0.5 mol / L.

3. The method for electrochemically assisted green leaching of retired lithium-ion batteries according to claim 1, characterized in that, In step (3), the material of the inert electrode is selected from platinum, titanium, and graphite.

4. The method for electrochemically assisted green leaching of retired lithium-ion batteries according to claim 1, characterized in that, In step (3), the initial voltage of the DC power supply is 0.5V to 3V.

5. The method for electrochemically assisted green leaching of retired lithium-ion batteries according to claim 1, characterized in that, In step (4), during the nickel ion leaching process, the power supply potential is 0.6V to 1.0V, and the nickel leaching rate is 90% to 98%.

6. The method for electrochemically assisted green leaching of retired lithium-ion batteries according to claim 1, characterized in that, In step (5), during the cobalt ion leaching process, the power supply potential is 1.2V to 1.6V, and the cobalt leaching rate is 85% to 95%.

7. The method for electrochemically assisted green leaching of retired lithium-ion batteries according to claim 1, characterized in that, In step (6), during the manganese ion leaching process, the power supply potential is 1.8V to 2.2V, and the manganese leaching rate is 80% to 95%.

8. The method for electrochemically assisted green leaching of retired lithium-ion batteries according to claim 1, characterized in that, During the leaching process of nickel, cobalt, and manganese ions, the ion concentration in the leachate is sampled and analyzed periodically. The leaching process ends when the ion concentration changes tend to stabilize.

9. The method for electrochemically assisted green leaching of retired lithium-ion batteries according to claim 1, characterized in that, In step (7), the precipitant is a sodium carbonate solution with a concentration of 0.05 mol / L to 0.2 mol / L, and the recovery rate of lithium obtained is 95% to 98%.

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