Method for controlled recovery of a product with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution and applications

Abstract

This invention provides a method and application for the controllable recovery of a specific cobalt-nickel ratio product from a cobalt-nickel mixed solution. The method includes the following steps: adding a complexing agent to the cobalt-nickel mixed solution and adjusting the pH of the solution to acidic, thus obtaining an electrolyte; using the electrolyte as the working electrolyte in an electrodeposition system, performing an electrodeposition reaction under constant potential conditions, causing the specific cobalt-nickel ratio product to deposit on the cathode surface; wherein the cobalt-nickel mixed solution contains cobalt ions and nickel ions. The recovery method of this invention is simple in procedure, reduces production costs, improves recovery efficiency and environmental friendliness, and has good prospects for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of metal recycling and material preparation technology, and particularly relates to a method and application for the controllable recovery of products with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution. Background Technology

[0002] With the rapid promotion of new energy vehicles, a large number of waste lithium-ion batteries are generated. Among them, ternary lithium-ion batteries, due to their high energy density, have become one of the mainstream power batteries and account for a large proportion of waste lithium-ion batteries. Ternary batteries contain high-value metal elements such as cobalt and nickel, to which my country has a high dependence on imports, and have high resource recycling value. However, if these metal elements are leaked into the environment during processing, they can easily cause serious environmental pollution problems. Therefore, efficient and environmentally friendly resource recycling of waste ternary batteries has become an inevitable requirement for my country's resource security and environmental protection. Currently, the resource recycling methods for waste ternary batteries mainly include three types: element separation and extraction, electrode material regeneration, and material upgrading and remanufacturing. Elemental separation and extraction typically involves high-temperature calcination or strong acid / alkali treatment to completely destroy the crystal structure of the electrode material. Then, selective precipitation, solvent extraction, and other methods are used to separate and purify the various metal elements. However, this process is complex and energy-intensive. Electrode material regeneration, on the other hand, restores the electrochemical performance of the cathode material through lithium compensation or structural repair without destroying the integrity of the crystal structure. However, its applicability is limited by the degree of damage to the electrode material. Material upgrading and remanufacturing, without elemental separation, directly utilizes the metal elements in waste ternary batteries to prepare other functional materials, such as catalysts. This eliminates the cumbersome elemental separation and extraction process and effectively reduces production costs.

[0003] In existing technologies, invention patent CN110743528A, "A Method for Preparing a Water Splitting Catalyst from Waste Batteries," prepares an electrolysis catalyst by electrodepositing the leachate from waste batteries; invention patent CN120838431A, "A Method for Preparing a Catalyst from Waste Ternary Lithium-ion Batteries and Its Application," prepares a catalyst for the selective oxidation of 5-hydroxymethylfurfural by combining a ternary leachate with kaolin using a microwave hydrothermal method. However, the performance of functional materials is closely related to their elemental ratios. Existing material upgrading and remanufacturing technologies often cannot precisely control the proportions of elements such as cobalt and nickel in the recycled products according to the performance requirements of the target material, resulting in unstable performance of the prepared materials. Based on this, this invention provides a method and application for the controllable recovery of products with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution, to solve the problems of uncontrollable proportions of elements such as cobalt and nickel in existing recycled products and complex procedures. Summary of the Invention

[0004] The main objective of this invention is to provide a method and application for the controllable recovery of products with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution, aiming to solve the technical problems of uncontrollable proportions of elements such as cobalt and nickel in existing recovered products and complex procedures.

[0005] To achieve the above objectives, the present invention provides a method for controllably recovering products with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution, comprising the steps of: S1: Add a complexing agent to the cobalt-nickel mixed solution and adjust the pH of the solution to acidic to obtain the electrolyte.

[0006] S2: Using the electrolyte as the working electrolyte of the electrodeposition system, an electrodeposition reaction is carried out under constant potential conditions to deposit the specific cobalt-nickel ratio product on the cathode surface.

[0007] The cobalt-nickel mixed solution contains cobalt ions and nickel ions.

[0008] According to embodiments of this application, the ligand includes an aminocarboxylic acid ligand.

[0009] The aminocarboxylic acid ligands include one or more of ethylenediaminetetraacetic acid (EDTA), disodium EDTA, trisodium EDTA, tetrasodium EDTA, or their hydrates.

[0010] According to an embodiment of this application, the pH value of the adjusting solution is 3.0 to 6.0.

[0011] The electrolyte contains cobalt complexes and / or nickel complexes.

[0012] According to an embodiment of this application, the ratio of the molar concentration of the ligand to the total molar concentration of the cobalt ions and nickel ions is 0.01 to 0.99.

[0013] According to an embodiment of this application, the temperature of the electrodeposition reaction is 10~60°C.

[0014] According to an embodiment of this application, the cathode of the electrodeposition reaction comprises a conductive substrate.

[0015] The anode of the electrodeposition reaction includes a carbon rod or a platinum sheet.

[0016] The reference electrode for the electrodeposition reaction includes a silver-silver chloride electrode or a mercury-mercurous sulfate electrode.

[0017] The cathode potential of the electrodeposition reaction is -0.3 to -1 V (relative to the standard hydrogen electrode).

[0018] According to embodiments of this application, the conductive substrate includes at least one of metal and carbon-based materials.

[0019] The metals include copper, gold, silver, and platinum.

[0020] The carbon-based materials include carbon cloth and carbon paper.

[0021] According to embodiments of this application, the specific cobalt-nickel ratio product includes a cobalt-nickel alloy.

[0022] According to the embodiments of this application, the time interval from obtaining the electrolyte to starting the electrodeposition reaction is 10 minutes to 14 days.

[0023] The present invention also provides an application of the product obtained by the above method for the controllable recovery of a specific cobalt-nickel ratio from a cobalt-nickel mixed solution in the preparation of lithium-ion battery cathode materials, catalysts, or high-purity cobalt sulfate.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: The aforementioned method for controllably recovering products with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution involves adding a complexing agent to the cobalt-nickel mixed solution and adjusting the pH of the solution to acidic, thereby forming a stable cobalt-nickel complex electrolyte. The complexing agent can selectively react with Ni in the cobalt-nickel mixed solution. 2+ A complexation reaction occurs, forming a stable nickel complex and a small amount of cobalt complex, while most of the Co... 2+ Existing in a free state, the concentration ratio of free cobalt and nickel ions in the solution is controlled through complexation, laying the concentration foundation for the subsequent electrodeposition preparation of products with specific cobalt-nickel ratios and achieving source control of the product ratio. The controlled solution is a weakly acidic environment, which can inhibit the hydrolysis and precipitation reactions of cobalt and nickel ions under weakly acidic conditions, ensuring the uniform dispersion of cobalt-nickel complexes in the electrolyte, avoiding unevenness of the electrodeposition system caused by ion precipitation, and improving the stability of the subsequent electrodeposition reaction. At the same time, pH can be used to control the cobalt-nickel ratio of the product. The electrolyte serves as the working electrolyte of the electrodeposition system. By controlling the constant potential of the electrodeposition system, the reduction reaction potential of the cathode is precisely controlled, so that the cobalt-nickel complexes in the electrolyte are reduced in an orderly manner under the set potential, thereby precisely controlling the cobalt-nickel ratio of the cathode deposition product and achieving controllable preparation of products with specific cobalt-nickel ratios. Driven by a constant potential, the cobalt-nickel complex gains electrons on the cathode surface and is reduced to metallic cobalt-nickel, which is then directionally deposited to form a solid product. This achieves efficient conversion of cobalt and nickel elements from the solution phase to the solid phase, completing the recovery and directional preparation of cobalt and nickel. By adjusting the type of ligand, pH value to acidity, temperature, and constant potential parameters, it can adapt to cobalt-nickel mixed solutions with different composition ranges, meeting the recovery requirements of various specific cobalt-nickel ratio products, and has strong process adaptability.

[0025] Moreover, the recycling method of the present invention has simple steps, and the product recycling is completed by only two core operations: pH adjustment by adding a ligand and constant potential electrodeposition. While achieving controllable recycling of cobalt and nickel, it simplifies the process, reduces production costs, and improves recycling efficiency and environmental friendliness, and has good prospects for industrial application. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0027] Figure 1 This is a comparison chart showing the cobalt-nickel ratio of the products recovered from the cobalt-nickel mixed solution in Examples 1, 2, and 3 and Comparative Example 1. Figure 2 The graph shows the change of the cobalt-nickel ratio of the electrodeposition product with EDTA concentration under the following conditions: pH 4.5, electrodeposition reaction temperature 20℃, cathode potential -0.65V (relative to the standard hydrogen electrode), and cobalt and nickel ion concentrations of 50 mmol / L in the cobalt-nickel mixed solution. Figure 3 The graph shows the relationship between the cobalt-nickel ratio of the electrodeposition product and the cathode potential when the pH is 4.5, the electrodeposition reaction temperature is 20℃, the concentrations of cobalt and nickel ions in the cobalt-nickel mixed solution are both 50 mmol / L, and the EDTA concentrations are 75, 85, and 95 mmol / L. Figure 4 The graph shows the relationship between the cobalt-nickel ratio of the electrodeposition product and the pH of the cobalt-nickel mixed solution when the cathode potential is -0.65V (relative to the standard hydrogen electrode), the electrodeposition reaction temperature is 20℃, the concentrations of cobalt and nickel ions in the cobalt-nickel mixed solution are both 50 mmol / L, and the EDTA concentrations are 75, 85, and 95 mmol / L. Figure 5 The graph shows the relationship between the cobalt-nickel ratio of the electrodeposition product and the temperature of the electrodeposition reaction when the cathode potential is -0.65V (relative to the standard hydrogen electrode), the pH is 4.5, the concentrations of cobalt and nickel ions in the cobalt-nickel mixed solution are both 50 mmol / L, and the EDTA concentrations are 75, 85, and 95 mmol / L.

[0028] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0031] To achieve the above objectives, the present invention provides a method for controllably recovering products with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution, comprising the steps of: S1: A complexing agent is added to the cobalt-nickel mixed solution, and the pH of the solution is adjusted to acidity to obtain an electrolyte. The cobalt-nickel mixed solution contains cobalt ions and nickel ions.

[0032] In some embodiments, the ligand comprises an aminocarboxylic acid ligand.

[0033] The aminocarboxylic acid ligands include one or more of ethylenediaminetetraacetic acid (EDTA), disodium EDTA, trisodium EDTA, tetrasodium EDTA, or their hydrates.

[0034] In some embodiments, the aminocarboxylic acid ligand includes one of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, trisodium ethylenediaminetetraacetic acid, tetrasodium ethylenediaminetetraacetic acid, or their hydrates.

[0035] In some embodiments, the molar concentration of the ligand is 60-95 mmol / L.

[0036] In some embodiments, the aminocarboxylic acid ligand includes ethylenediaminetetraacetic acid tetrasodium tetrahydrate.

[0037] In some embodiments, aminocarboxylic acid ligands can react with Co. 2+ and Ni 2+ It forms a stable complex and reacts with Ni. 2+ The resulting complexes are more stable and produce a "selectivity window," with aminocarboxylic acid ligands reacting with most Ni compounds. 2+ A complexation reaction occurs, forming a stable complex, while most Co... 2+ Existing in a free state, it regulates the concentration ratio of free cobalt and nickel ions in the solution through complexation, laying the concentration foundation for subsequent electrodeposition to prepare products with specific cobalt-nickel ratios, thus achieving source control of the product ratio.

[0038] S2: Using the electrolyte as the working electrolyte of the electrodeposition system, an electrodeposition reaction is carried out under constant potential conditions, causing the specific cobalt-nickel ratio product to be deposited on the cathode surface. Since the adsorption and electron transport kinetics of the cobalt complex at the electrode interface are superior to those of the nickel complex, the cobalt-nickel ratio of the product is further amplified relative to the free cobalt-nickel ratio in solution. The selectivity is further amplified by utilizing the difference in the interaction between the cobalt and nickel complexes at the electrode interface, thus achieving the deposition of the specific cobalt-nickel ratio product on the cathode surface.

[0039] The aforementioned method for controllably recovering products with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution involves adding a complexing agent to the cobalt-nickel mixed solution and adjusting the pH of the solution to acidic, thereby forming a stable cobalt-nickel complex electrolyte. The complexing agent can selectively react with Ni in the cobalt-nickel mixed solution. 2+ A complexation reaction occurs, forming a stable nickel complex and a small amount of cobalt complex, while most of the Co... 2+ Existing in a free state, the concentration ratio of free cobalt and nickel ions in the solution is controlled through complexation, laying the concentration foundation for the subsequent electrodeposition preparation of products with specific cobalt-nickel ratios and achieving source control of the product ratio. The controlled solution is a weakly acidic environment, which can inhibit the hydrolysis and precipitation reactions of cobalt and nickel ions under weakly acidic conditions, ensuring the uniform dispersion of cobalt-nickel complexes in the electrolyte, avoiding unevenness of the electrodeposition system caused by ion precipitation, and improving the stability of the subsequent electrodeposition reaction. At the same time, pH can be used to control the cobalt-nickel ratio of the product. The electrolyte serves as the working electrolyte of the electrodeposition system. By controlling the constant potential of the electrodeposition system, the reduction reaction potential of the cathode is precisely controlled, so that the cobalt-nickel complexes in the electrolyte are reduced in an orderly manner under the set potential, thereby precisely controlling the cobalt-nickel ratio of the cathode deposition product and achieving controllable preparation of products with specific cobalt-nickel ratios. Driven by a constant potential, the cobalt-nickel complex gains electrons on the cathode surface and is reduced to metallic cobalt-nickel, which is then directionally deposited to form a solid product. This achieves efficient conversion of cobalt and nickel elements from the solution phase to the solid phase, completing the recovery and directional preparation of cobalt and nickel. By adjusting the type of ligand, pH value to acidity, and constant potential parameters, it can adapt to cobalt-nickel mixed solutions with different composition ranges, meeting the recovery requirements of various specific cobalt-nickel ratio products, and has strong process adaptability.

[0040] In some embodiments, the pH value is 3.0 to 6.0.

[0041] The electrolyte contains cobalt complexes and / or nickel complexes.

[0042] In some embodiments, the pH value is 3.0 to 4.0.

[0043] In some embodiments, the electrolyte contains a cobalt complex and a nickel complex.

[0044] In some embodiments, the electrolyte contains a nickel complex.

[0045] In some embodiments, the temperature of the electrodeposition reaction is 10~60°C.

[0046] In some embodiments, the electrodeposition reaction lasts from 10 minutes to 20 days.

[0047] In some embodiments, the duration of the electrodeposition reaction is 10 min to 3 h.

[0048] In some embodiments, the temperature of the electrodeposition reaction is 20~60°C.

[0049] The electrodeposition reaction lasts for 1.5 to 2.5 hours.

[0050] In some embodiments, the step of performing the electrodeposition reaction under constant potential conditions includes: A conductive substrate is used as the cathode, a carbon rod or platinum sheet is used as the anode, and a silver-silver chloride electrode or a mercury-mercurous sulfate electrode is used as the reference electrode. A potential is applied to the cathode to carry out the electrodeposition reaction.

[0051] The potential of the cathode is -0.3 to -1V (relative to the standard hydrogen electrode).

[0052] In some embodiments, a copper sheet is used as the cathode, a carbon rod or platinum sheet is used as the anode, and a silver-silver chloride electrode or a mercury-mercurous sulfate electrode is used as the reference electrode. A potential is applied to the cathode to perform an electrodeposition reaction.

[0053] The potential of the cathode is -0.55 to -0.75V (relative to the standard hydrogen electrode).

[0054] In some embodiments, a three-electrode system (working electrode / counter electrode / reference electrode) can be used to precisely control the cathode potential (-0.3~-1V vs. SHE), avoiding the potential fluctuations caused by solution resistance in traditional two-electrode systems, achieving a uniform current density distribution, thereby obtaining a deposition layer with uniform thickness and a smooth surface.

[0055] In some embodiments, the ratio of the molar concentration of the ligand to the total molar concentration of the cobalt and nickel ions is 0.01 to 0.99.

[0056] In some embodiments, the ratio of the molar concentration of the ligand to the total molar concentration of the cobalt and nickel ions is 0.05 to 0.95.

[0057] In some embodiments, the ratio of the molar concentration of the ligand to the total molar concentration of the cobalt and nickel ions is 0.25 to 0.95.

[0058] In some embodiments, the molar concentration of the ligand is 0.25 to 0.95 of the total molar concentration of the cobalt and nickel ions, and the atomic ratio of cobalt to nickel in the resulting product with a specific cobalt-nickel ratio is 5 to 611:1.

[0059] In some embodiments, the ratio of the molar concentration of the ligand to the total molar concentration of the cobalt and nickel ions is 0.75 to 0.95, and when the pH of the electrolyte is 3.0 to 6.0, the atomic ratio of cobalt to nickel in the obtained product with a specific cobalt-nickel ratio is 98 to 611:1.

[0060] In some embodiments, the molar concentration of the ligand is 0.75 to 0.95 of the total molar concentration of the cobalt and nickel ions, and when the potential applied to the cathode is -0.55 to -0.75V (relative to a standard hydrogen electrode), the atomic ratio of cobalt to nickel in the resulting product with a specific cobalt-nickel ratio is 154 to 611:1.

[0061] In some embodiments, when the molar concentration of the ligand is 0.75 to 0.95 of the total molar concentration of cobalt and nickel ions, the pH of the electrolyte is 4.2 to 4.8, and the temperature of the electrodeposition reaction is 20 to 60°C, the atomic ratio of cobalt to nickel in the obtained product with a specific cobalt-nickel ratio is 73 to 611:1.

[0062] In some embodiments, the conductive substrate includes at least one of metal and carbon-based materials.

[0063] The metals include copper, gold, silver, and platinum.

[0064] The carbon-based materials include carbon cloth and carbon paper.

[0065] In some embodiments, the conductive substrate includes one of metal and carbon-based materials.

[0066] The metals include copper and silver.

[0067] In some embodiments, the specific cobalt-nickel ratio product includes a cobalt-nickel alloy.

[0068] In some embodiments, the atomic ratio of cobalt to nickel in the cobalt-nickel alloy is 4:1 to 611:1.

[0069] In some embodiments, the time interval from obtaining the electrolyte to starting the electrodeposition reaction is 10 minutes to 14 days.

[0070] In some embodiments, at room temperature, the time interval from the preparation of the electrolyte to the start of the electrodeposition reaction is 10 minutes to 14 days.

[0071] In some embodiments, the cobalt-nickel mixed solution comprises a solution obtained by leaching cobalt and nickel-containing materials.

[0072] In the cobalt-nickel mixed solution, the atomic ratio of cobalt to nickel is (0.8~1.2):(0.8~1.2).

[0073] Moreover, the recycling method of the present invention has simple steps, and the product recycling is completed by only two core operations: pH adjustment by adding a ligand and constant potential electrodeposition. While achieving controllable recycling of cobalt and nickel, it simplifies the process, reduces production costs, and improves recycling efficiency and environmental friendliness, and has good prospects for industrial application.

[0074] The present invention also provides an application of the product obtained by the above method for the controllable recovery of a specific cobalt-nickel ratio from a cobalt-nickel mixed solution in the preparation of lithium-ion battery cathode materials, catalysts, or high-purity cobalt sulfate.

[0075] In some embodiments, the product obtained by the above method for the controlled recovery of a specific cobalt-nickel ratio from a cobalt-nickel mixed solution can also be used to prepare catalysts for high-purity cobalt or nitrate reduction or water electrolysis.

[0076] To further illustrate the present invention, the following examples are provided: It should be noted that, in the embodiments and comparative examples of this invention, reagents or instruments whose manufacturers are not specified are considered to be conventional products that can be purchased commercially.

[0077] In the embodiments and comparative examples of this invention, the cobalt-nickel mixed solution was obtained by acid leaching of lithium cobalt nickel manganese oxide (NCM111) produced by a domestic manufacturer to remove manganese, and the atomic ratio of cobalt to nickel was 1:1.

[0078] Example 1 A method for the controlled recovery of products with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution, comprising the following steps: S1: A complexing agent (0.769 g tetrasodium ethylenediaminetetraacetate tetrahydrate) was added to a 20 mL cobalt-nickel mixed solution with a cobalt ion concentration of 50 mmol / L and a nickel ion concentration of 50 mmol / L. The pH of the solution was adjusted to acidic (pH 4.5) to obtain the electrolyte. The cobalt-nickel mixed solution contained cobalt ions (Co... 2+ ) and nickel ions (Ni 2+ The ratio of the molar concentration of the ligand to the total molar concentration of cobalt and nickel ions is 0.85.

[0079] S2: Using an electrolyte as the working electrolyte in the electrodeposition system, an electrodeposition reaction is carried out under constant potential conditions to deposit a product with a specific cobalt-nickel ratio on the cathode surface; a copper sheet is used as the cathode, a carbon rod as the anode, and a silver-silver chloride electrode as the reference electrode. A potential is applied to the cathode to carry out the electrodeposition reaction; the cathode potential is -0.65V (relative to the standard hydrogen electrode), the electrodeposition reaction temperature is 20℃, the electrodeposition reaction time is 2h, and a product with a specific cobalt-nickel ratio (cobalt-nickel alloy) is obtained on the cathode; the time interval from the preparation of the electrolyte to the start of the electrodeposition reaction is 7 days.

[0080] Tests showed that in Example 1, the atomic ratio of cobalt to nickel in the specific cobalt-nickel ratio product obtained on the cathode was 611:1.

[0081] Analysis and verification: 1. Verification of the effect of the ratio of the molar concentration of the ligand to the total molar concentration of cobalt and nickel ions on the atomic ratio of cobalt to nickel in the specific cobalt-nickel ratio product obtained on the cathode.

[0082] S1: Add a ligand (tetrasodium ethylenediaminetetraacetate) to a 20 mL cobalt-nickel mixed solution with a cobalt ion concentration of 50 mmol / L and adjust the pH of the solution to 4.5, so that the molar concentration of the ligand to the total molar concentration of cobalt and nickel ions are 0.25, 0.45, 0.55, 0.65, 0.75, 0.85, and 0.95, respectively.

[0083] S2: Using an electrolyte as the working electrolyte in the electrodeposition system, an electrodeposition reaction is carried out under constant potential conditions to deposit a product with a specific cobalt-nickel ratio on the cathode surface; a copper sheet is used as the cathode, a carbon rod as the anode, and a silver-silver chloride electrode as the reference electrode. A potential is applied to the cathode to carry out the electrodeposition reaction; the cathode potential is -0.65V (relative to the standard hydrogen electrode), the electrodeposition reaction temperature is 20℃, the electrodeposition reaction duration is 2h, and a product with a specific cobalt-nickel ratio (cobalt-nickel alloy) is obtained on the cathode; at room temperature, the time interval from the preparation of the electrolyte to the start of the electrodeposition reaction is 7 days.

[0084] Tests showed that different ratios of the molar concentration of the ligand to the total molar concentration of cobalt and nickel ions correspond to different atomic ratios of cobalt and nickel in products with specific cobalt-nickel ratios. (See [reference needed]). Figure 2The ratio of the molar concentration of the ligand to the total molar concentration of cobalt and nickel ions is 0.25, with an atomic ratio of cobalt to nickel of 5:1; the ratio of the molar concentration of the ligand to the total molar concentration of cobalt and nickel ions is 0.45, with an atomic ratio of cobalt to nickel of 13:1; the ratio of the molar concentration of the ligand to the total molar concentration of cobalt and nickel ions is 0.55. The atomic ratio of cobalt to nickel is 53:1; the ratio of the molar concentration of the ligand to the total molar concentration of cobalt and nickel ions is 0.65, and the atomic ratio of cobalt to nickel is 175:1; the ratio of the molar concentration of the ligand to the total molar concentration of cobalt and nickel ions is 0.75, and the atomic ratio of cobalt to nickel is 369:1; the ratio of the molar concentration of the ligand to the total molar concentration of cobalt and nickel ions is 0.85, and the atomic ratio of cobalt to nickel is 611:1; the ratio of the molar concentration of the ligand to the total molar concentration of cobalt and nickel ions is 0.95, and the atomic ratio of cobalt to nickel is 363:1.

[0085] 2. Verification of the effect of applying different potentials to the cathode on the atomic ratio of cobalt to nickel in the specific cobalt-nickel ratio product obtained on the cathode.

[0086] S1: Add a ligand (tetrasodium ethylenediaminetetraacetate) to a 20 mL cobalt-nickel mixed solution with cobalt and nickel ion concentrations of 50 mmol / L. The molar concentration ratio of the added ligand to the total molar concentration of cobalt and nickel ions is 0.75, 0.85, and 0.95, respectively. Adjust the potential applied to the cathode to -0.55, -0.6, -0.65, -0.7, and -0.75 V (relative to a standard hydrogen electrode).

[0087] S2: Using an electrolyte as the working electrolyte in the electrodeposition system, an electrodeposition reaction is carried out under constant potential conditions to deposit a product with a specific cobalt-nickel ratio on the cathode surface; a copper sheet is used as the cathode, a carbon rod as the anode, and a silver-silver chloride electrode as the reference electrode. A potential is applied to the cathode to carry out the electrodeposition reaction; the electrodeposition reaction temperature is 20℃, the electrodeposition reaction time is 2h, and a product with a specific cobalt-nickel ratio (cobalt-nickel alloy) is obtained on the cathode; the time interval from the preparation of the electrolyte to the start of the electrodeposition reaction is 7 days.

[0088] Tests showed that the cobalt-nickel ratio in the electrodeposited products varied depending on the cathode applied potential. (See [reference needed]). Figure 3When the ratio of the molar concentration of the ligand to the sum of the cobalt-nickel ion concentrations is 0.75, the cathode potentials are -0.55, -0.6, -0.65, -0.7, and -0.75 V (relative to the standard hydrogen electrode), and the cobalt-nickel ratios are 177, 243, 335, 289, and 227, respectively. When the ratio is 0.85, the cathode potentials are -0.55, -0.6, -0.65, -0.7, and -0.75 V (relative to the standard hydrogen electrode), and the cobalt-nickel ratios are 202, 351, 611, 452, and 245, respectively. When the ratio is 0.95, the cathode potentials are -0.55, -0.6, -0.65, -0.7, and -0.75 V (relative to the standard hydrogen electrode), and the cobalt-nickel ratios are 154, 447, and 370, respectively. 394 and 241.

[0089] 3. Verification of the effect of different pH values ​​of the solution on the atomic ratio of cobalt to nickel in the specific cobalt-nickel ratio product obtained on the cathode.

[0090] S1: Add a complexing agent (tetrasodium ethylenediaminetetraacetate) to a 20 mL cobalt-nickel mixed solution with a cobalt ion concentration of 50 mmol / L. The molar concentration of the added complexing agent is 0.75, 0.85, and 0.95 of the total molar concentration of cobalt and nickel ions, respectively. Adjust the pH of the electrolyte to 3.0, 4.0, 4.5, 5.0, and 6.0, respectively.

[0091] S2: Using an electrolyte as the working electrolyte in the electrodeposition system, an electrodeposition reaction is carried out under constant potential conditions to deposit a product with a specific cobalt-nickel ratio on the cathode surface; a copper sheet is used as the cathode, a carbon rod as the anode, and a silver-silver chloride electrode as the reference electrode. A potential is applied to the cathode to carry out the electrodeposition reaction; the cathode potential is -0.65V (relative to the standard hydrogen electrode), the electrodeposition reaction temperature is 20℃, the electrodeposition reaction time is 2h, and a product with a specific cobalt-nickel ratio (cobalt-nickel alloy) is obtained on the cathode; the time interval from the preparation of the electrolyte to the start of the electrodeposition reaction is 7 days.

[0092] Tests showed that the cobalt-nickel ratio in the electrodeposition products varied depending on the pH of the electrolyte. (See [link to relevant documentation]). Figure 4When the ratio of the molar concentration of the ligand to the sum of the cobalt and nickel ion concentrations is 0.75, and the pH values ​​are 3.0, 4.0, 4.5, 5.0, and 6.0, the cobalt-nickel ratios are 314, 386, 369, 142, and 131, respectively. When the ratio of the molar concentration of the ligand to the sum of the cobalt and nickel ion concentrations is 0.85, and the pH values ​​are 3.0, 4.0, 4.5, 5.0, and 6.0, the cobalt-nickel ratios are 584, 482, 611, 175, and 154, respectively. When the ratio of the molar concentration of the ligand to the sum of the cobalt and nickel ion concentrations is 0.75, and the pH values ​​are 3.0, 4.0, 4.5, 5.0, and 6.0, the cobalt-nickel ratios are 433, 545, 363, 172, and 98, respectively.

[0093] 4. Verification of the effect of different electrodeposition reaction temperatures (hereinafter referred to as temperature) on the atomic ratio of cobalt to nickel in the specific cobalt-nickel ratio product obtained on the cathode.

[0094] S1: Add a complexing agent (tetrasodium ethylenediaminetetraacetate) to a 20 mL cobalt-nickel mixed solution with a cobalt ion concentration of 50 mmol / L and a nickel ion concentration of 50 mmol / L. The molar concentration of the added complexing agent is 0.75, 0.85, and 0.95 of the total molar concentration of cobalt ions and nickel ions, respectively. Adjust the pH of the electrolyte to 4.5.

[0095] S2: Using an electrolyte as the working electrolyte in the electrodeposition system, an electrodeposition reaction is carried out under constant potential conditions to deposit a product with a specific cobalt-nickel ratio on the cathode surface; a copper sheet is used as the cathode, a carbon rod as the anode, and a silver-silver chloride electrode as the reference electrode. A potential is applied to the cathode to carry out the electrodeposition reaction; the cathode potential is -0.65V (relative to the standard hydrogen electrode), the electrodeposition reaction time is 2 hours, and a product with a specific cobalt-nickel ratio (cobalt-nickel alloy) is obtained on the cathode. The time interval from the preparation of the electrolyte to the start of the electrodeposition reaction is 7 days.

[0096] Tests showed that the cobalt-nickel ratio in the electrodeposition product varied depending on the electrodeposition reaction temperature. (See [reference needed]). Figure 5 When the ratio of the molar concentration of the ligand to the sum of the cobalt-nickel ion concentrations is 0.75, the cobalt-nickel ratios at electrodeposition temperatures of 20℃, 30℃, 40℃, 50℃, and 60℃ are 335, 284, 200, 124, and 119, respectively. When the ratio is 0.85, the cobalt-nickel ratios at the same temperatures are 611, 424, 158, 145, and 114, respectively. When the ratio is 0.95, the cobalt-nickel ratios at the same temperatures are 363, 310, 137, 99, and 73, respectively.

[0097] Example 2 Compared to Example 1, the mass of the ligand was changed.

[0098] In Example 2, the mass of the ligand was 0.497 g (the molar concentration of the ligand was 0.55 times the total molar concentration of cobalt and nickel ions), and the pH of the solution was 4.5. Other steps were the same as in Example 1, resulting in a product (cobalt-nickel alloy) with a specific cobalt-nickel ratio on the cathode.

[0099] Tests showed that in Example 2, the atomic ratio of cobalt to nickel in the specific cobalt-nickel ratio product obtained on the cathode was 55:1.

[0100] Example 3 Compared to Example 1, the mass of the ligand, anode, and reference electrode materials were changed.

[0101] In Example 3, the mass of the ligand was 0.226 g (the ratio of the molar concentration of the ligand to the total molar concentration of cobalt and nickel ions was 0.25), the pH of the solution was 4.5, a platinum sheet was used as the anode, a mercury-mercurous sulfate electrode was used as the reference electrode, and the cathode potential was -0.65 V (relative to the standard hydrogen electrode). Other steps were the same as in Example 1, and a product with a specific cobalt-nickel ratio (cobalt-nickel alloy) was obtained on the cathode.

[0102] Tests showed that in Example 3, the atomic ratio of cobalt to nickel in the specific cobalt-nickel ratio product obtained on the cathode was 5:1.

[0103] Comparative Example 1 A method for the controlled recovery of products with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution, comprising the following steps: S1: Add 1 ml of 10 mol / L NaOH solution to a 20 mL cobalt-nickel mixed solution with a cobalt ion concentration of 50 mmol / L and a nickel ion concentration of 50 mmol / L. Stir and mix well. The separated solid is the recovered product with a specific cobalt-nickel ratio.

[0104] Because Comparative Example 1 uses a chemical precipitation method, lacking coordination and electrodeposition steps, the atomic ratio of cobalt to nickel in the recovered product with a specific cobalt-nickel ratio cannot be further controlled. (See [link to relevant documentation]). Figure 1 Tests showed that in Comparative Example 1, the atomic ratio of cobalt to nickel in the recovered specific cobalt-nickel ratio product was 1:1.

[0105] The aforementioned method for controllably recovering products with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution involves adding a complexing agent to the cobalt-nickel mixed solution and adjusting the pH of the solution to acidic, thereby forming a stable cobalt-nickel complex electrolyte. The complexing agent can selectively react with Ni in the cobalt-nickel mixed solution. 2+ A complexation reaction occurs, forming a stable nickel complex and a small amount of cobalt complex, while most of the Co...2+ Existing in a free state, the concentration ratio of free cobalt and nickel ions in the solution is controlled through complexation, laying the concentration foundation for the subsequent electrodeposition preparation of products with a specific cobalt-nickel ratio, thus achieving source control of the product ratio. The controlled solution is a weakly acidic environment, which can inhibit the hydrolysis and precipitation reactions of cobalt and nickel ions under weakly acidic conditions, ensuring the uniform dispersion of cobalt-nickel complexes in the electrolyte, avoiding unevenness of the electrodeposition system caused by ion precipitation, and improving the stability of the subsequent electrodeposition reaction. At the same time, pH can be used to control the cobalt-nickel ratio of the product. The electrolyte serves as the working electrolyte of the electrodeposition system. By controlling the constant potential of the electrodeposition system, the reduction reaction potential of the cathode is precisely controlled, so that the cobalt-nickel complexes in the electrolyte are reduced in an orderly manner under the set potential, thereby precisely controlling the cobalt-nickel ratio of the cathode deposition product and achieving controllable preparation of products with a specific cobalt-nickel ratio. Driven by a constant potential, the cobalt-nickel complex gains electrons on the cathode surface and is reduced to metallic cobalt-nickel, which is then directionally deposited to form a solid product. This achieves efficient conversion of cobalt and nickel elements from the solution phase to the solid phase, completing the recovery and directional preparation of cobalt and nickel. By adjusting the type of ligand, pH value to acidity, and constant potential parameters, it can adapt to cobalt-nickel mixed solutions with different composition ranges, meeting the recovery requirements of various specific cobalt-nickel ratio products, and has strong process adaptability.

[0106] Moreover, the recycling method of the present invention has simple steps, and the product recycling is completed by only two core operations: pH adjustment by adding a ligand and constant potential electrodeposition. While achieving controllable recycling of cobalt and nickel, it simplifies the process, reduces production costs, and improves recycling efficiency and environmental friendliness, and has good prospects for industrial application.

[0107] In summary, the above-described technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for the controlled recovery of a product with a specific cobalt to nickel ratio from a cobalt-nickel mixed solution, characterized in that, Including the following steps: S1: Add a complexing agent to the cobalt-nickel mixed solution and adjust the pH of the solution to acidic to obtain the electrolyte; S2: Using the electrolyte as the working electrolyte of the electrodeposition system, an electrodeposition reaction is carried out under constant potential conditions to deposit a product with a specific cobalt-nickel ratio on the cathode surface. The cobalt-nickel mixed solution contains cobalt ions and nickel ions.

2. The method for controllably recovering a product with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution according to claim 1, characterized in that, The ligands include aminocarboxylic acid ligands; The aminocarboxylic acid ligands include one or more of ethylenediaminetetraacetic acid (EDTA), disodium EDTA, trisodium EDTA, tetrasodium EDTA, or their hydrates.

3. The method for controllably recovering a product with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution according to claim 1, characterized in that, The pH value is 3.0~6.0; The electrolyte contains cobalt complexes and / or nickel complexes.

4. The method for controllably recovering a product with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution according to claim 1, characterized in that, The ratio of the molar concentration of the ligand to the total molar concentration of the cobalt and nickel ions is 0.01 to 0.

99.

5. The method for controllably recovering a product with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution according to claim 1, characterized in that, The electrodeposition reaction is carried out at a temperature of 10~60℃.

6. The method for controllably recovering a product with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution according to claim 1, characterized in that, The cathode of the electrodeposition reaction includes a conductive substrate; The anode of the electrodeposition reaction includes a carbon rod or a platinum sheet; The reference electrode for the electrodeposition reaction includes a silver-silver chloride electrode or a mercury-mercurous sulfate electrode; The cathode potential of the electrodeposition reaction is -0.3 to -1 V (relative to the standard hydrogen electrode).

7. The method for controllably recovering a product with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution according to claim 6, characterized in that, The conductive substrate includes at least one of metal and carbon-based materials; The metals include copper, gold, silver, and platinum; The carbon-based materials include carbon cloth, carbon paper, and carbon felt.

8. The method for controllably recovering a product with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution according to claim 1, characterized in that, The specific cobalt-nickel ratio product includes cobalt-nickel alloys.

9. The method for controllably recovering a product with a specific cobalt-nickel ratio from a cobalt-nickel mixed solution according to claim 1, characterized in that, The time interval from the preparation of the electrolyte to the start of the electrodeposition reaction is 10 minutes to 14 days.

10. The application of a product with a specific cobalt-nickel ratio that can be controllably recovered from a cobalt-nickel mixed solution by the method according to any one of claims 1 to 9 in the preparation of lithium-ion battery cathode materials, catalysts, or high-purity cobalt sulfate.

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