Method for preparing ternary cathode precursor from waste battery based on oxygen cathode electrolysis

Abstract

The application provides a method for preparing ternary positive electrode precursors from waste batteries based on an oxygen cathode electrolysis, and the steps are as follows: waste lithium ion battery ternary positive electrode material powder is immersed in acid to obtain activated carbon black and a leaching solution containing metal elements; the leaching solution is extracted to realize the separation of Li + solution and a ternary salt solution containing Ni 2+ , Co 2+ , Mn 2+ ; the ternary salt solution is adjusted to obtain a ternary salt compound solution with Ni, Co and Mn elements reaching a set ratio; and the lithium ion battery ternary positive electrode precursor material is obtained by electrolysis of an oxygen cathode electrolytic cell. The oxygen cathode electrolytic cell is a three-chamber electrolytic cell, dilute sulfuric acid is introduced into the anode chamber, sodium sulfate solution and the ternary salt compound solution are introduced into the cathode chamber, and oxygen is introduced into the gas chamber. The application directly and efficiently produces NCM ternary positive electrode material precursors while recycling and processing waste ternary positive electrode materials. The oxygen cathode has high catalytic efficiency, can effectively avoid the reduction and deposition of metal in the cathode, greatly reduces the cell voltage, reduces energy consumption, and greatly saves costs.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste lithium-ion battery recycling, and in particular relates to a method for preparing a ternary positive electrode precursor by recycling waste batteries based on oxygen cathode electrolysis. Background Art

[0002] In recent years, the development of energy storage devices with superior electrochemical performance has become a major research focus. Lithium-ion batteries, due to their high energy density, long cycle life, and environmentally friendly properties, are widely used in portable electronic products such as mobile phones, camcorders, and laptops. With the maturation of the new energy vehicle industry, lithium-ion batteries have been widely used in new energy vehicles. Market research predicts that by 2030, new energy vehicle sales will account for 40% of the total automotive industry, reaching 12 to 16 million units. Due to the demand for electric vehicle range within the new energy vehicle industry, high-energy-density ternary materials will find wider application, and the market share of ternary lithium-ion batteries is expected to increase further in the future.

[0003] my country relies heavily on imported lithium resources and is short on cobalt resources, making it the largest consumer of cobalt. However, ternary cathode materials contain high concentrations of Co, Ni, Mn, and Li. Failure to effectively recycle these resources will directly lead to significant waste. Over time, the number of retired batteries continues to increase. It is estimated that by 2025, the amount of scrapped power batteries alone will reach 100GWh, and by 2030, it will reach 300GWh. If recycled, the recycling value would exceed 30 billion yuan in 2025. As a result, many new lithium battery recycling plants are being added around the world, and existing ones are also expanding their capacity. From an environmental perspective, the valuable metal ions (Li, Co, Ni, Mn, etc.) in ternary cathode materials are diverse and high in concentration. If left untreated or improperly handled, they can cause serious pollution and significant harm to water, soil, and human health. Therefore, recycling and reusing spent lithium-ion batteries has a significant impact on both environmental improvement and economic development, generating significant economic and social benefits.

[0004] At present, there are two main methods for recycling waste lithium-ion battery materials:

[0005] The first type is a combination of pyrometallurgy and wet metallurgy, which mainly involves calcining lithium-ion battery waste powder at high temperature under a certain environment (such as a reducing agent, chlorine or sulfur dioxide atmosphere), and then obtaining the corresponding lithium product through leaching and other purification steps. This type of method has the disadvantages of high energy consumption and environmental unfriendliness, such as generating a large amount of exhaust gas and wastewater.

[0006] The second type is the full wet process, which avoids the generation of waste gas and is mainly based on acid leaching. However, this method only produces low value-added products and has limited application value. Alternatively, acid leaching is combined with electrolysis to treat lithium-ion battery waste powder. For example, after acid leaching, it is electrolyzed by ion membrane method, using sodium sulfate waste liquid and leaching solution containing Li, Ni, Co, and Mn commonly produced in industry as electrolytes. While effectively recycling the waste sodium sulfate waste liquid, it directly produces the positive electrode material precursor of the ternary lithium-ion battery. However, this method ignores Ni. 2+ 、Co 2+ It is easy for reduction reaction to occur directly at the cathode and precipitate in the form of metal, which leads to the problem that the electrolysis process cannot proceed smoothly and the NCM ratio is difficult to control, which is not conducive to its large-scale application. Summary of the Invention

[0007] In view of this, the purpose of the present invention is to provide a method for preparing a ternary positive electrode precursor based on recycling waste batteries by oxygen cathode electrolysis, aiming to solve at least one technical problem among the background technologies.

[0008] The present invention is achieved in that:

[0009] A method for preparing a ternary positive electrode precursor by recycling waste batteries based on oxygen cathode electrolysis, the steps are as follows:

[0010] Acid leaching of waste lithium-ion battery ternary cathode material powder to obtain activated carbon black and a leachate containing metal elements;

[0011] Extract the leachate to achieve Li + The solution is separated from the ternary salt solution, and the ternary salt includes at least Ni 2+ 、Co 2+ 、Mn 2+ ;

[0012] The ternary salt solution is heated and the Ni / Co / Mn / salt solution is added to obtain a ternary salt composite solution in which the Ni, Co, and Mn elements reach a set ratio.

[0013] The hydroxide precursors of Ni, Co and Mn are prepared by using an oxygen cathode electrolytic cell to obtain the precursor material of the ternary positive electrode of lithium-ion batteries;

[0014] The oxygen cathode electrolyzer is a three-chamber electrolyzer, comprising an anode chamber, a cathode chamber and a gas chamber. Dilute sulfuric acid is introduced into the anode chamber, sodium sulfate solution and the ternary salt compound solution are introduced into the cathode chamber, and oxygen is introduced into the gas chamber.

[0015] Preferably, the concentration of the dilute sulfuric acid introduced into the anode chamber is 0.1 to 2 mol / L;

[0016] The concentration of sodium sulfate solution introduced into the cathode chamber is 0.1-2 mol / L, and the Ni content in the ternary salt composite solution is 2+ 、Co 2+ 、Mn 2 + The total concentration is 0.5 to 2 mol / L;

[0017] The flow rate of oxygen introduced into the gas chamber is 350-450 mL / min, and the oxygen pressure is maintained at 0.08-0.12 MPa.

[0018] Preferably, the current density of electrolysis is set to 1.5-4 kA / m 2 ; The electrolysis temperature is set to 40~80℃.

[0019] Preferably, in the oxygen cathode electrolyzer, an anion membrane is provided between the cathode chamber and the anode chamber, an oxygen cathode is provided between the cathode chamber and the gas chamber; and an anode plate is built into the anode chamber.

[0020] Preferably, the oxygen cathode comprises a gas diffusion layer, a current collector and a catalyst layer connected in parallel in sequence, the gas diffusion layer is a porous carbon black-polytetrafluoroethylene layer, the current collector is a titanium mesh, and the catalyst layer is a carbon-supported platinum catalyst-polytetrafluoroethylene layer; the gas diffusion layer is placed in the gas chamber, and the catalyst layer is placed in the cathode chamber.

[0021] Preferably, the anode plate is a titanium electrode coated with ruthenium oxide.

[0022] Preferably, after electrolysis, a hydroxide precursor precipitate and a sodium sulfate solution are obtained in the cathode chamber; and a concentrated sulfuric acid solution and oxygen are obtained in the anode chamber;

[0023] The sodium sulfate solution is recycled as the reaction solution in the cathode chamber;

[0024] The concentrated sulfuric acid solution is recovered and used as a leaching agent for acid leaching;

[0025] The oxygen is recovered and used as the oxygen cathode of the gas chamber to generate reduction reaction gas.

[0026] Preferably, the leaching agent for the acid leaching is sulfuric acid.

[0027] Preferably, the extraction agent used in the extraction is a dicarboxylic acid extractant, preferably tartaric acid.

[0028] Preferably, the molar ratio of Ni:Co:Mn in the ternary salt composite solution is (1-8):(1-1.5):1; the Ni / Co / Mn / salt solution is NiSO4, CoSO4 and MnSO4.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The present invention not only recycles and processes waste lithium-ion battery ternary cathode materials, but also directly and efficiently produces a precursor of the ternary cathode material of the lithium-ion battery, and the proportion of NCM in the precursor is controllable;

[0031] (2) The liquid phase components in the oxygen cathode electrolysis production process of the present invention can be recycled, and the oxygen generated at the anode can also be used for the cathode reaction;

[0032] (3) The production process of the present invention does not emit any waste residue, waste gas, or waste liquid, and is highly safe and environmentally friendly;

[0033] (4) The present invention adopts oxygen cathode ion membrane electrolysis, which can avoid the direct reduction and precipitation of nickel, cobalt and manganese ions, and the obtained precursor product is pure and has good morphology quality;

[0034] (5) The present invention adopts an oxygen cathode with high catalytic efficiency and low theoretical potential of oxygen reduction reaction at the cathode, which can effectively avoid metal reduction and precipitation at the cathode, while greatly reducing the cell voltage, reducing energy consumption, and greatly saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a process flow chart of the present invention;

[0036] Figure 2 Schematic diagram of the structure and principle of the oxygen cathode electrolyzer in the present invention.

[0037] Illustration: 1-gas chamber, 2-cathode chamber, 3-anion membrane, 4-anode chamber, 5-anode plate, 6-oxygen cathode, 61-gas diffusion layer, 62-current collector, 63-catalytic layer. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific implementation cases described herein are only used to explain the present invention and are not intended to limit the present invention.

[0039] like Figure 1 As shown, the method for preparing a ternary positive electrode precursor by recycling waste batteries based on oxygen cathode electrolysis is as follows:

[0040] (1) acid leaching waste lithium-ion battery ternary cathode material powder to obtain activated carbon black and a leachate containing metal elements;

[0041] Using sulfuric acid as a leaching agent, an acid leaching method is adopted to leach metal elements in the waste lithium-ion battery ternary cathode material powder into a liquid phase, and after solid-liquid separation, activated carbon black and a leachate containing metal elements are obtained, wherein the activated carbon black can be recycled;

[0042] (2) Extract the leachate to achieve Li + solution and ternary salt solution separation;

[0043] The metal element-containing leaching solution obtained in step (1) is extracted with tartaric acid to obtain the Li-containing leaching solution after separation. + Solution and Ni 2+ 、Co 2+ 、Mn 2+ A solution containing Li + The solution is carbonized and precipitated to recover lithium;

[0044] (3) adding Ni / Co / Mn / salt solution to prepare the ternary salt solution to obtain a ternary salt composite solution in which Ni, Co, and Mn elements reach a set ratio;

[0045] Contains Ni 2+ 、Co 2+ 、Mn 2+ The solution is passed into a storage tank for heating and the ratio of Ni, Co and Mn elements is adjusted by adding NiSO4, CoSO4 and MnSO4. The adjusted molar ratio of Ni:Co:Mn is (1-8): (1-1.5):1 to form a ternary salt composite solution, preferably 1:1:1 or 3:1:1 or 2.5:1.5:1 or 8:1:1;

[0046] (4) using an oxygen cathode electrolytic cell to prepare hydroxide precursors of Ni, Co, and Mn to obtain a ternary positive electrode precursor material for lithium-ion batteries;

[0047] Among them, Figure 2 As shown, the oxygen cathode electrolyzer is a three-chamber electrolyzer, including a gas chamber 1, a cathode chamber 2 and an anode chamber 4. An anion membrane 3 is provided between the cathode chamber 2 and the anode chamber 4, and an oxygen cathode 6 is provided between the cathode chamber 2 and the gas chamber 1; the anode chamber 4 has an anode plate 5 built in.

[0048] The oxygen cathode 6 comprises a gas diffusion layer 61, a current collector 62, and a catalyst layer 63, which are connected in parallel. The gas diffusion layer 61 is a porous carbon black-polytetrafluoroethylene layer, the current collector 62 is a titanium mesh, and the catalyst layer 63 is a carbon-supported platinum catalyst-polytetrafluoroethylene layer. The gas diffusion layer 61 is placed in the gas chamber 1, and the catalyst layer 63 is placed in the cathode chamber 2. The anode plate 5 is a titanium electrode coated with ruthenium oxide. The anion membrane 3 can be a conventional anion exchange membrane. In the following examples, a FUMASEP FAB-PK-130 anion membrane is used.

[0049] In a specific implementation, dilute sulfuric acid with a concentration of 0.1 to 2 mol / L is introduced into the anode chamber 4, and a sodium sulfate solution with a concentration of 0.1 to 2 mol / L is introduced into the cathode chamber 2. The role of sodium sulfate is a supporting electrolyte to improve the conductivity of the solution. When electrolysis starts, the ternary salt composite solution with a concentration of 0.5 to 2 mol / L obtained in step (3) is introduced into the cathode chamber 2, and oxygen is introduced into the gas chamber 1 at 400 mL / min, and the oxygen pressure is maintained at 0.1 MPa. The current density of the electrolysis is set to 1.5 to 4 kA / m 2 The electrolysis temperature is set to 40-80°C. The electrolysis reaction mechanism is:

[0050] 2H2O=4H + +O2+4e;2H + +SO4 2- =H2SO4;

[0051] 2H2O+4e+O2=4OH - ;xNi 2+ +yCo 2+ +(1-xy)Mn 2+ +2OH - =Ni x Co y Mn 1-x-y (OH)2.

[0052] After electrolysis, a hydroxide precursor precipitate and a sodium sulfate solution are obtained in the cathode chamber 2; a concentrated sulfuric acid solution and oxygen are obtained in the anode chamber 4; the concentrated sulfuric acid solution is transported to the acid leaching process of step (1), and the oxygen is transported to the oxygen storage tank through a pipeline, mixed with pure oxygen, and the gas pressure is adjusted, and then transported to the gas chamber through a pipeline for a reduction reaction at the oxygen cathode;

[0053] The product in the cathode chamber 2 is separated into a solid and liquid state, and the hydroxide precursor is collected and precipitated, and then the lithium-ion battery ternary positive electrode precursor material Ni is obtained through conventional heat treatment such as drying and sintering. x Co y Mn 1-x-y (OH)2; the sodium sulfate solution returns to the cathode chamber for recycling.

[0054] Example 1

[0055] An embodiment of the present invention provides a method for preparing a ternary cathode precursor by recycling waste batteries based on oxygen cathode electrolysis, comprising the following steps:

[0056] Step (1) acid leaching to obtain a leachate of metal elements

[0057] A 1.5 mol / L sulfuric acid solution was used to leach the powder of the ternary positive electrode material of waste lithium-ion batteries, so that the metal elements such as Li, Ni, Co, and Mn in the positive electrode material were leached into the liquid phase. Through solid-liquid separation, activated carbon black and a leachate containing metal elements such as Li, Ni, Co, and Mn were obtained. The activated carbon black was sintered to prepare the negative electrode material for lithium-ion batteries.

[0058] Step (2) extraction and separation of Li + Separation of solution and ternary salt solution

[0059] The leachate obtained in step 1 was extracted using tartaric acid as an extractant, and the Li-containing + and Ni 2 + 、Co 2+ 、Mn 2+ solution, to the solution containing Li + The solution is added with Na2CO3 to obtain precipitated Li2CO3 to recover lithium;

[0060] Step (3) Preparation of ternary salt composite solution

[0061] Containing Ni 2+ 、Co 2+ 、Mn 2+ The solution was heated to 60 ° C, and NiSO4, CoSO4, and MnSO4 were added to adjust the molar ratio of nickel, cobalt, and manganese elements to Ni: Co: Mn = 1: 1: 1. The Ni content of the prepared ternary salt composite solution was 2+ 、Co 2+ 、Mn 2+ The total ion concentration is 2 mol / L.

[0062] Step (4) Electrolysis in an oxygen cathode electrolytic cell to obtain hydroxide precursors of Ni, Co, and Mn

[0063] Electrolysis was carried out using an oxygen cathode electrolyzer, in which a FUMASEP FAB-PK-130 anion membrane was installed between the cathode chamber and the anode chamber; an oxygen cathode was installed between the cathode chamber and the gas chamber, and the oxygen cathode included a gas diffusion layer, a current collector, and a catalyst layer. The gas diffusion layer was a porous carbon black-polytetrafluoroethylene (PTFE) layer, the current collector was a titanium mesh, and the catalyst layer was a commercial carbon-supported platinum catalyst-polytetrafluoroethylene (PTFE) layer; the anode material was a coated titanium electrode plated with ruthenium oxide.

[0064] First, the ion membrane was pretreated and installed. A dilute sulfuric acid solution with a concentration of 0.5 mol / L was introduced into the anode chamber, and a sodium sulfate solution with a concentration of 2 mol / L was introduced into the cathode chamber as a supporting electrolyte. After power was applied, the leachate obtained in step (3) was introduced into the cathode chamber of the electrolytic cell, and oxygen was introduced into the gas chamber of the electrolytic cell. The oxygen flow rate was 400 mL / min to maintain the oxygen pressure at 0.1 MPa. The current density during the electrolysis process was 2.5 kA / m 2 , the electrolysis temperature is 60℃.

[0065] After electrolysis, hydroxide precursor precipitates of Ni, Co, and Mn and a sodium sulfate solution are obtained in the cathode chamber of the electrolytic cell, and a concentrated sulfuric acid solution is obtained in the anode chamber of the electrolytic cell.

[0066] Step (5) post-processing of electrolysis products

[0067] The concentrated sulfuric acid solution obtained in the anode chamber is recovered as a leaching agent for acid leaching and transported to the leaching process of step (1);

[0068] The oxygen generated in the anode chamber during the electrolysis process is recovered and transported to the oxygen storage tank through a pipeline. After being mixed with pure oxygen and the gas pressure adjusted, it is then transported to the gas chamber through a pipeline for reduction reaction at the oxygen cathode. The residual unreacted oxygen flows back to the storage tank.

[0069] After the electrolysis is completed, the precipitate and solution in the cathode chamber are filtered, and the sodium sulfate solution obtained by solid-liquid separation is transported to the anode chamber of the electrolytic cell for recycling. The hydroxide precursor precipitates of Ni, Co, and Mn are dried and baked, and the product is Ni 1 / 3 Co 1 / 3 Mn 1 / 3 (OH)2, determined by ICP, the Ni:Co:Mn of the precipitate is 0.334:0.333:0.333, which is very close to the pre-set ratio of 1:1:1.

[0070] Example 2

[0071] An embodiment of the present invention provides a method for preparing a ternary cathode precursor by recycling waste batteries based on oxygen cathode electrolysis, comprising the following steps:

[0072] Step (1) acid leaching to obtain a leachate of metal elements

[0073] Same as Example 1.

[0074] Step (2) extraction and separation of Li + Separation of solution and ternary salt solution

[0075] Same as Example 1.

[0076] Step (3) Preparation of ternary salt composite solution

[0077] Containing Ni 2+ 、Co 2+ 、Mn 2+ The solution was heated to 80 ° C, and NiSO4, CoSO4, and MnSO4 were added to adjust the molar ratio of nickel, cobalt, and manganese elements to Ni: Co: Mn = 3: 1: 1. The Ni content of the prepared ternary salt composite solution was 2+ 、Co 2+ 、Mn 2+ The total ion concentration is 1 mol / L.

[0078] Step (4) Electrolysis in an oxygen cathode electrolytic cell to obtain hydroxide precursors of Ni, Co, and Mn

[0079] Electrolysis was performed using an oxygen cathode electrolyzer having the same structure as in Example 1. First, the ion membrane was pretreated and installed, a dilute sulfuric acid solution with a concentration of 0.1 mol / L was introduced into the anode chamber, and a sodium sulfate solution with a concentration of 0.1 mol / L was introduced into the cathode chamber as a supporting electrolyte. After power was applied, the leachate obtained in step (3) was introduced into the cathode chamber of the electrolyzer, and oxygen was introduced into the gas chamber of the electrolyzer. The oxygen flow rate was 350 mL / min to maintain the oxygen pressure at 0.08 MPa. The current density during the electrolysis process was 1.5 kA / m 2 , the electrolysis temperature is 80℃.

[0080] After electrolysis, hydroxide precursor precipitates of Ni, Co, and Mn and a sodium sulfate solution are obtained in the cathode chamber of the electrolytic cell, and a concentrated sulfuric acid solution is obtained in the anode chamber of the electrolytic cell.

[0081] Step (5) post-processing of electrolysis products

[0082] The concentrated sulfuric acid solution obtained in the anode chamber is recovered as a leaching agent for acid leaching and transported to the leaching process of step (1);

[0083] The oxygen generated in the anode chamber during the electrolysis process is recovered and transported to the oxygen storage tank through a pipeline. After being mixed with pure oxygen and the gas pressure adjusted, it is then transported to the gas chamber through a pipeline for reduction reaction at the oxygen cathode. The residual unreacted oxygen flows back to the storage tank.

[0084] After the electrolysis is completed, the precipitate and solution in the cathode chamber are filtered, and the sodium sulfate solution obtained by solid-liquid separation is transported to the anode chamber of the electrolytic cell for recycling. The hydroxide precursor precipitates of Ni, Co, and Mn are dried and baked, and the product is Ni 3 / 5 Co 1 / 5 Mn 1 / 5 (OH)2, determined by ICP, the Ni:Co:Mn of the precipitate is 1.002:0.334:0.333, which is very close to the pre-set ratio of 3:1:1.

[0085] Example 3

[0086] An embodiment of the present invention provides a method for preparing a ternary cathode precursor by recycling waste batteries based on oxygen cathode electrolysis, comprising the following steps:

[0087] Step (1) acid leaching to obtain a leachate of metal elements

[0088] Same as Example 1.

[0089] Step (2) extraction and separation of Li + Separation of solution and ternary salt solution

[0090] Same as Example 1.

[0091] Step (3) Preparation of ternary salt composite solution

[0092] Containing Ni 2+ 、Co 2+ 、Mn 2+ The solution was heated to 80°C, and NiSO4, CoSO4, and MnSO4 were added to adjust the molar ratio of nickel, cobalt, and manganese elements to Ni:Co:Mn=2.5:1.5:1. The Ni content of the prepared ternary salt composite solution was 2+ 、Co 2+ 、Mn 2+ The total ion concentration is 1.5 mol / L.

[0093] Step (4) Electrolysis in an oxygen cathode electrolytic cell to obtain hydroxide precursors of Ni, Co, and Mn

[0094] Electrolysis was performed using an oxygen cathode electrolyzer having the same structure as in Example 1. First, the ion membrane was pretreated and installed, a dilute sulfuric acid solution with a concentration of 1 mol / L was introduced into the anode chamber, and a sodium sulfate solution with a concentration of 1 mol / L was introduced into the cathode chamber as a supporting electrolyte. After power was applied, the leachate obtained in step (3) was introduced into the cathode chamber of the electrolyzer, and oxygen was introduced into the gas chamber of the electrolyzer. The oxygen flow rate was 450 mL / min to maintain the oxygen pressure at 0.12 MPa. The current density during the electrolysis process was 4 kA / m 2 , the electrolysis temperature is 40℃.

[0095] After electrolysis, hydroxide precursor precipitates of Ni, Co, and Mn and a sodium sulfate solution are obtained in the cathode chamber of the electrolytic cell, and a concentrated sulfuric acid solution is obtained in the anode chamber of the electrolytic cell.

[0096] Step (5) post-processing of electrolysis products

[0097] The concentrated sulfuric acid solution obtained in the anode chamber is recovered as a leaching agent for acid leaching and transported to the leaching process of step (1);

[0098] The oxygen generated in the anode chamber during the electrolysis process is recovered and transported to the oxygen storage tank through a pipeline. After being mixed with pure oxygen and the gas pressure adjusted, it is then transported to the gas chamber through a pipeline for reduction reaction at the oxygen cathode. The residual unreacted oxygen flows back to the storage tank.

[0099] After the electrolysis is completed, the precipitate and solution in the cathode chamber are filtered, and the sodium sulfate solution obtained by solid-liquid separation is transported to the anode chamber of the electrolytic cell for recycling. The hydroxide precursor precipitates of Ni, Co, and Mn are dried and baked, and the product is Ni 1 / 2 Co 3 / 10 Mn 1 / 5 (OH)2, determined by ICP, the Ni:Co:Mn ratio of the precipitate is 0.833:0.500:0.333, which is very close to the preset ratio of 2.5:1.5:1.

[0100] Example 4

[0101] An embodiment of the present invention provides a method for preparing a ternary cathode precursor by recycling waste batteries based on oxygen cathode electrolysis, comprising the following steps:

[0102] Step (1) acid leaching to obtain a leachate of metal elements

[0103] Same as Example 1.

[0104] Step (2) extraction and separation of Li + Separation of solution and ternary salt solution

[0105] Same as Example 1.

[0106] Step (3) Preparation of ternary salt composite solution

[0107] Containing Ni 2+ 、Co 2+ 、Mn 2+ The solution was heated to 80°C, and NiSO4, CoSO4, and MnSO4 were added to adjust the molar ratio of nickel, cobalt, and manganese elements to Ni:Co:Mn=8:1:1. The Ni content in the prepared ternary salt composite solution was 2+ 、Co 2+ 、Mn 2+ The total ion concentration is 0.5 mol / L.

[0108] Step (4) Electrolysis in an oxygen cathode electrolytic cell to obtain hydroxide precursors of Ni, Co, and Mn

[0109] Electrolysis was performed using an oxygen cathode electrolyzer with the same structure as in Example 1. First, the ion membrane was pretreated and installed, a dilute sulfuric acid solution with a concentration of 0.5 mol / L was introduced into the anode chamber, and a sodium sulfate solution with a concentration of 0.5 mol / L was introduced into the cathode chamber as a supporting electrolyte. After power was applied, the leachate obtained in step (3) was introduced into the cathode chamber of the electrolytic cell, and oxygen was introduced into the gas chamber of the electrolytic cell. The oxygen flow rate was 400 mL / min to maintain the oxygen pressure at 0.1 MPa. The current density during the electrolysis process was 3 kA / m 2 , the electrolysis temperature is 70℃.

[0110] After electrolysis, hydroxide precursor precipitates of Ni, Co, and Mn and a sodium sulfate solution are obtained in the cathode chamber of the electrolytic cell, and a concentrated sulfuric acid solution is obtained in the anode chamber of the electrolytic cell.

[0111] Step (5) post-processing of electrolysis products

[0112] The concentrated sulfuric acid solution obtained in the anode chamber is recovered as a leaching agent for acid leaching and transported to the leaching process of step (1);

[0113] The oxygen generated in the anode chamber during the electrolysis process is recovered and transported to the oxygen storage tank through a pipeline. After being mixed with pure oxygen and the gas pressure adjusted, it is then transported to the gas chamber through a pipeline for reduction reaction at the oxygen cathode. The residual unreacted oxygen flows back to the storage tank.

[0114] After the electrolysis is completed, the precipitate and solution in the cathode chamber are filtered, and the sodium sulfate solution obtained by solid-liquid separation is transported to the anode chamber of the electrolytic cell for recycling. The hydroxide precursor precipitates of Ni, Co, and Mn are dried and baked, and the product is Ni 4 / 5 Co 1 / 10 Mn 1 / 10 (OH)2, determined by ICP, the Ni:Co:Mn of the precipitate is 2.666:0.333:0.333, which is very close to the pre-set ratio of 8:1:1.

[0115] Comparative Example 1

[0116] This comparative example provides a method for electrolytically recovering ternary cathode materials from waste lithium-ion batteries, using a conventional three-chamber electrolytic cell. The remaining parameters and steps are the same as those in Example 1:

[0117] In the three-chamber electrolytic cell used in this comparative example, a cationic membrane is provided between the cathode chamber and the middle tank of the electrolytic cell, and the cationic membrane is a Nafion-117 perfluorosulfonic acid ion membrane; an anionic membrane is provided between the anode chamber and the middle tank of the electrolytic cell, and the anionic membrane is an AMI-7001 quaternary ammonium anionic membrane; the anode material is a titanium electrode plated with an iridium-ruthenium coating, and the cathode material is a nickel cathode plated with a platinum-carbon coating.

[0118] A 0.5 mol / L sulfuric acid solution is introduced into the anode chamber of the electrolytic cell, a 2 mol / L sodium sulfate waste liquid is introduced into the middle tank of the electrolytic cell, and a 0.5 mol / L sodium hydroxide solution, a 0.5 mol / L ammonia solution and the leachate obtained in step 2 are introduced into the cathode chamber of the electrolytic cell, wherein the ammonia solution needs to be added during the first electrolysis process and does not need to be added again thereafter, and can be obtained by electrolysis of an ammonium sulfate solution; the current density during the electrolysis process is 2.5 kA / m 2 , the electrolysis temperature is 60 ° C. After electrolysis, the hydroxide precursor precipitation of Ni, Co, and Mn, sodium sulfate solution and ammonium sulfate solution are obtained in the cathode chamber of the electrolytic cell, and concentrated sulfuric acid solution is obtained in the anode chamber of the electrolytic cell.

[0119] After the electrolysis is completed, the precipitate and solution in the cathode chamber are filtered, and the sodium sulfate solution obtained by solid-liquid separation is transported to the anode chamber of the electrolytic cell for recycling. The hydroxide precursor precipitates of Ni, Co, and Mn are dried and dried, and the products are mainly Ni 2 / 7 Co 2 / 75 Mn 3 / 7 (OH)2, and also contains a small amount of manganese, cobalt, and nickel. According to ICP determination, the molar ratio of Ni:Co:Mn of the hydroxide precipitate of Ni, Co, and Mn is 0.203:0.201:0.302, which is about 2:2:3, which is very different from the set ratio of 1:1:1. The reason is that Ni 2+ 、Co 2+ 、Mn 2+ It is easy to undergo a reduction reaction directly at the cathode and precipitate in the form of metal, which makes it difficult to control the proportion of NCM in the final precursor material.

[0120] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a ternary cathode precursor by recycling waste batteries based on oxygen cathode electrolysis, characterized in that: The method steps are as follows: Acid leaching of waste lithium-ion battery ternary cathode material powder to obtain activated carbon black and a leachate containing metal elements; Extract the leachate to achieve Li + The solution is separated from the ternary salt solution, and the ternary salt solution includes at least Ni 2+ 、Co 2+ 、Mn 2+ ; The ternary salt solution is heated and a Ni / Co / Mn / salt solution is added to obtain a ternary salt composite solution containing Ni, Co, and Mn elements at a set ratio. The molar ratio of Ni:Co:Mn in the ternary salt composite solution is (1-8):(1-1.5):

1. The Ni / Co / Mn / salt solution contains NiSO4, CoSO4, and MnSO4. The hydroxide precursors of Ni, Co and Mn are prepared by using an oxygen cathode electrolytic cell to obtain the precursor material of the ternary positive electrode of lithium-ion batteries; Among them, the oxygen cathode electrolyzer is a three-chamber electrolyzer, including an anode chamber, a cathode chamber and a gas chamber. Dilute sulfuric acid is introduced into the anode chamber, sodium sulfate solution and the ternary salt composite solution are introduced into the cathode chamber, and oxygen is introduced into the gas chamber. In the oxygen cathode electrolyzer, an anion membrane is provided between the cathode chamber and the anode chamber, and an oxygen cathode is provided between the cathode chamber and the gas chamber. An anode plate is built into the anode chamber.

2. The method for preparing a ternary cathode precursor by recycling waste batteries based on oxygen cathode electrolysis according to claim 1, characterized in that: The concentration of dilute sulfuric acid introduced into the anode chamber is 0.1 to 2 mol / L; The concentration of sodium sulfate solution introduced into the cathode chamber is 0.1-2 mol / L, and the Ni content in the ternary salt composite solution is 2+ 、Co 2+ 、Mn 2+ The total concentration is 0.5 to 2 mol / L; The oxygen flow rate into the gas chamber is 350~450mL / min, and the oxygen pressure is maintained at 0.08~0.12MPa.

3. The method for preparing a ternary cathode precursor by recycling waste batteries based on oxygen cathode electrolysis according to claim 1 or 2, characterized in that: The current density of electrolysis is set to 1.5~4kA / m 2 ; The electrolysis temperature is set to 40~80℃.

4. The method for preparing a ternary cathode precursor by recycling waste batteries based on oxygen cathode electrolysis according to claim 1, characterized in that: The oxygen cathode comprises a gas diffusion layer, a current collector and a catalyst layer connected in parallel in sequence, the gas diffusion layer is a porous carbon black-polytetrafluoroethylene layer, the current collector is a titanium mesh, and the catalyst layer is a carbon-supported platinum catalyst-polytetrafluoroethylene layer; the gas diffusion layer is placed in the gas chamber, and the catalyst layer is placed in the cathode chamber.

5. The method for preparing a ternary cathode precursor by recycling waste batteries based on oxygen cathode electrolysis according to claim 1 or 4, characterized in that: The anode plate adopts a coated titanium electrode with ruthenium oxide plated on the surface.

6. The method for preparing a ternary cathode precursor by recycling waste batteries based on oxygen cathode electrolysis according to claim 1, characterized in that: After electrolysis, a hydroxide precursor precipitate and a sodium sulfate solution are obtained in the cathode chamber; and a concentrated sulfuric acid solution and oxygen are obtained in the anode chamber; The sodium sulfate solution is recycled as the reaction solution in the cathode chamber; The concentrated sulfuric acid solution is recovered and used as a leaching agent for acid leaching; The oxygen is recovered and used as the oxygen cathode of the gas chamber to generate reduction reaction gas.

7. The method for preparing a ternary cathode precursor by recycling waste batteries based on oxygen cathode electrolysis according to claim 1, characterized in that: The leaching agent of the acid leaching is sulfuric acid.

8. The method for preparing a ternary cathode precursor by recycling waste batteries through oxygen cathode electrolysis according to claim 1, characterized in that: The extraction agent used in the extraction is a dicarboxylic acid extraction agent.

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