A method for recycling positive electrode materials of ternary lithium battery

Abstract

The present invention relates to a method for recovering retired ternary lithium battery positive electrode materials, wherein the ternary positive electrode materials are sequentially stripped, crushed, and acid-leached, and then subjected to two electrolytic cell treatments, wherein the first treatment is carried out at a pH of 3 to 6, and the acid leaching solution is used as an electrolyte at a temperature of 10 to 100 A / m 2 Electrolysis is carried out for 3-8 hours at a current density of , and MnO2 at the anode of the electrolytic cell, the Ni-Co complex at the cathode of the electrolytic cell, and the lithium salt in the electrolyte are obtained respectively. The lithium salt is precipitated by sodium carbonate to separate Li, Mn, and Ni-Co. The recovery rate of each metal is high and the purity is good. After that, the electrode containing the Ni-Co complex is continued to be electrolyzed in the electrolytic cell, and the metal nickel and cobalt are separated by controlling parameters such as pH and electrolyte composition. The present invention can efficiently and accurately recover the valuable metals of the ternary positive electrode materials of retired lithium-ion batteries through simple electrolytic cell treatment, is simple to operate and has high economic value.

Description

Technical Field

[0001] The present invention relates to the technical field of battery recycling, and in particular to a method for recycling positive electrode materials of retired ternary lithium batteries. Background Art

[0002] With the sustained and stable development of new energy electric vehicles in my country, batteries have been widely used as carriers of electric energy, especially ternary lithium-ion batteries with high energy density, long cycle life and good safety performance. It is expected that the installed capacity of ternary lithium batteries for electric vehicles will increase greatly to about 97.70GWh by 2025. Lithium-ion batteries will undergo hundreds of cycles of charge and discharge during use. During the charging and discharging process, the internal structure of lithium-ion batteries is also quietly undergoing irreversible changes, resulting in the attenuation of lithium battery capacity. In more serious cases, it will lead to the loss of battery life and battery scrapping, thus limiting the average life of the entire lithium-ion battery system to about 3 to 5 years.

[0003] Waste lithium-ion batteries mainly contain anode and cathode materials, electrolytes, membranes and current collectors, most of which are harmful to the environment. A large number of waste lithium-ion batteries pose a potential threat to the health of the urban environment, especially heavy metals, electrolytes, solvents and various organic auxiliary materials. At the same time, positive electrode materials are an important component of lithium-ion batteries and have a great impact on the performance of lithium-ion batteries. Positive electrode materials account for 30% to 40% of the cost of lithium-ion batteries, which directly determines the cost of lithium-ion batteries. In waste lithium-ion batteries, the positive electrode materials contain a large amount of valuable metals and also have great recycling value.

[0004] The metal recovery in the positive active materials of waste ternary lithium batteries mainly includes pyrometallurgy and hydrometallurgy. Pyrometallurgy directly extracts metals or metal oxides in the electrode through high-temperature treatment. The process is simple, but the purity of the recovered materials is low, and harmful gases are easily generated during the reaction, which leads to environmental pollution. Hydrometallurgy is to enrich the valuable metals in the solution through pretreatment, leaching and metal extraction of ternary materials, and then separate them to obtain the corresponding salts or oxides of each metal. The recovery of valuable metals in ternary positive electrode materials mainly involves the separation and recovery steps of each metal in the leachate. At present, the metal separation and recovery in the industry generally adopts solvent extraction, chemical precipitation, etc. to achieve the separation and extraction of valuable metals or directly use NiCoMn-containing materials as precursors to prepare ternary positive electrode materials. For example, CN107419096A discloses a preparation method for recycling ternary positive electrode materials from waste lithium batteries. The ternary material precursor is obtained by coprecipitation under alkaline conditions and calcined with lithium carbonate after ball milling to make a regenerated ternary positive electrode material. The invention does not separate and recover the valuable metals in the ternary material. The extraction method refers to selecting a specific extractant or a mixture of several extractants to form a stable complex with the target metal ion. The complex is separated from the leachate in the organic extractant, and then the metal ions in the complex are extracted with the corresponding solvent to achieve separation and purification of the metal ions. The advantage of the extraction method is good selectivity. Using different extractants, a high-concentration target metal ion solution can be obtained. However, the extractant will be lost to a certain extent during the extraction process, and the price of the extractant is relatively high, which makes this method have certain limitations in metal recovery. For example, CN114717419A discloses a method for separating and recovering nickel, cobalt, manganese and lithium from waste ternary lithium batteries. The method leaches the metal of the positive electrode powder of the waste ternary lithium battery, removes impurities, and then uses dimethylglyoxime to complex and precipitate the nickel in the impurity-removed liquid to separate the nickel-removed liquid; extracts the manganese in the nickel-removed liquid with P204 to obtain a loaded organic phase 1 and a raffinate 1, and the loaded organic phase 1 is washed and stripped with dilute sulfuric acid to obtain a manganese sulfate solution, and potassium permanganate is added to precipitate to generate manganese dioxide; the raffinate 1 is extracted with C272 to obtain a loaded organic phase 2 and a raffinate 2, and the loaded organic phase 2 is washed and stripped with dilute sulfuric acid to obtain a cobalt sulfate solution, and oxalic acid is added to precipitate to generate cobalt oxalate, and sodium carbonate is added to the raffinate 2 to precipitate to generate lithium carbonate. This method requires a large amount of extract, is costly, and has certain toxicity. The chemical precipitation method is a method of adding an appropriate precipitant to the metal leaching solution to react and produce precipitation to achieve metal ion separation. Commonly used precipitants include sodium hydroxide, ammonium oxalate, oxalic acid, sodium carbonate, etc. The advantages of chemical precipitation are low equipment requirements, low cost, and simple operation. The metal ions in the solution are precipitated step by step to obtain metal precipitates separated at each level to achieve separation. However, since the leachate contains multiple metal ions, co-precipitation is prone to occur, making it difficult to separate.For example, CN115305354A discloses a method for recovering precious metals such as nickel, cobalt, manganese and lithium from waste ternary lithium batteries. After the anode material of the ternary lithium battery is crushed into powder and dissolved in acid solution, a reducing agent is added to react the metal in the anode material of the ternary lithium battery with the acid solution, so that the metal that can react with the acid solution is completely dissolved in the acid solution, and the metal that does not react with the acid solution is precipitated; then filtering is performed to obtain filtrate A1 and filter residue B1. Acid leaching-stepwise separation is used to extract various precious metals from waste ternary lithium battery powders, and physical and chemical methods are used to separate various metal substances from mixed metal powders by utilizing the unique chemical properties of various metal substances. This method has a high demand for impurity removal in the early stage, and the steps are cumbersome, and the product purity is not high.

[0005] It can be seen that the existing methods for recovering valuable metals from waste lithium batteries still have a lot to be improved. In order to facilitate later use, it is necessary to develop a simple and easy method for recovering the positive electrode materials of retired lithium-ion batteries that can completely separate the valuable metals from the ternary positive electrode materials. Summary of the invention

[0006] The purpose of the present invention is to provide a method for recycling the positive electrode material of retired ternary lithium batteries to solve the disadvantages of the existing methods for recycling valuable metals from waste batteries, such as complex process, high recycling cost, and difficulty in completely separating valuable metals. The valuable metals in the present invention refer to metals with recycling value in waste batteries.

[0007] The invention provides a method for recovering a ternary positive electrode material for a lithium ion battery, comprising the following steps: step 1: crushing the ternary positive electrode material for a lithium ion battery into powder and dissolving the powder in dilute sulfuric acid to form a solution 1, wherein the concentration of the dilute sulfuric acid is 1.5M to 2.5M, then adding a reducing agent to the solution 1, wherein the reducing agent is one of hydrogen peroxide, sodium thiosulfate and sodium sulfite, continuously stirring and heating the solution 1 to which the reducing agent is added to 50 to 80°C, reacting for 2 to 10 hours to obtain an acidified leaching solution; step 2: adjusting the pH of the leaching solution to 3 to 6, then using the leaching solution as an electrolyte at 10 to 100A / m 2 The electrolysis treatment is carried out at a current density of , the electrode of the electrolytic cell is Pt or a graphite electrode, stirring is continued during the electrolysis process, and the electrolysis time is 3 to 8 hours, wherein the anode and cathode of the electrolytic cell can be independently selected from any one of Pt or graphite electrodes; step 3: after the electrolysis is completed, the leaching solution is filtered, and an alkaline solution is added to the filtrate to adjust its pH to 8 to 11, and then excess sodium carbonate is added to react with lithium precipitation, and after the reaction, the lithium carbonate is obtained by filtering and separating; step 4: the anode and cathode of the electrolytic cell are taken out, and the anode is cleaned and dried to obtain MnO 2After cleaning and drying, the cathode is placed in an electrolytic cell as an anode. The electrolyte is a nickel sulfate solution with a concentration of 50 to 200 g / L and an alkali solution adjusted to pH 7 to 8. The cathode is a Pt or graphite electrode at 20 to 100 A / m 2 Electrolysis is carried out at a current density of 4 to 8 hours, after which the anode and cathode of the electrolytic cell are taken out, and metal Co is obtained after the anode is cleaned and dried, and metal Ni is obtained after the cathode is cleaned and dried.

[0008] Preferably, the concentration of the dilute sulfuric acid is 1.5M, 1.6M, 1.7M, 1.8M, 1.9M, 2.0M, 2.1M, 2.2M, 2.3M, 2.4M, 2.5M. The reducing agent may be one of hydrogen peroxide, sodium thiosulfate, and sodium sulfite. After the reducing agent is added to the dilute sulfuric acid, the concentration of the reducing agent is 5 to 30 g / L, preferably 10 g / L, 15 g / L, 20 g / L, and 25 g / L. Preferably, after the reducing agent is added, the solid-liquid ratio of the ternary positive electrode material to the sulfuric acid / reducing agent solution in the system is 50 to 200 g / L. After the reducing agent is added to the system, the system is continuously stirred until the acidification leaching is completed. The acidification leaching reaction temperature is preferably 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 60°C, 60°C, and the reaction time may also be preferably 3h, 4h, 5h, 6h, 7h, and 8h. Continuous stirring throughout the system can promote uniform dispersion between the solid and liquid phases, and also facilitate the dispersion and dissolution of the ternary positive electrode materials and the reduction of high-valent metal ions.

[0009] Preferably, the electrolytic cell electrode is selected from any one of Pt or graphite electrodes, the cathode and the anode can be the same or different, and the shape of the electrolytic cell electrode is plate-shaped, rod-shaped or filament-shaped. The filtration in step 3 can also be other solid-liquid separation methods, including but not limited to decantation, filtration and centrifugal separation.

[0010] Preferably, before step 1, at least the retired lithium-ion battery is discharged, disassembled, the active material is stripped from the current collector, and the active positive electrode material is crushed. Preferably, the discharge treatment is to immerse the lithium-ion battery in a saturated NaCl solution for 3 to 10 hours. The active material can be stripped from the current collector by ultrasonic treatment, NMP dissolution, and alkaline solution treatment.

[0011] Preferably, after acid leaching in step 2, the pH of the leachate is adjusted to 3, 4, 5, or 6. The solution used to adjust the pH is an alkaline solution, which can be an aqueous solution of any one of 0.01 to 1 M sodium hydroxide, potassium hydroxide, ammonia water, or ammonium salt. The concentration of the alkaline solution is preferably 0.05 to 1 M. Preferably, the alkaline solution is a NaOH solution with a concentration of 0.1 to 0.5 M. The electrolytic treatment in step 2 is carried out in a conventional electrolytic cell, and the electrodes of the electrolytic cell are independently Pt or graphite electrodes. During the electrolytic treatment, the current density is controlled to be 10 to 100 A / m2 The preferred current density is 20A / m 2 、30A / m 2 , 40A / m 2 , 50A / m 2 、60A / m 2 , 70A / m 2 、80A / m 2 、90A / m 2 The current density is related to the electrolytic reaction speed. In order to control the reaction to proceed uniformly, the current density can be appropriately reduced; when the current density exceeds 100A / m 2 When the current density increases, the electrolysis process is fast, and the substances on the electrodes of the electrolytic cell will absorb other metal substances that are not diffused in time in the electrolyte to a certain extent. When the current density continues to increase, the purity of the valuable metals in the electrolytic electrode will decrease, which is not conducive to the separation of the valuable metals in the ternary positive electrode material. The electrolysis time in step 2 is preferably 5 to 7 hours, and more preferably 6 hours.

[0012] Preferably, in step 3, the alkaline solution for adjusting the pH is a NaOH solution with a concentration of 0.01 to 1M, and the pH is adjusted to 9 or 10. After adjusting the pH, an excess of sodium carbonate is added to the system to perform a lithium precipitation reaction, and the metallic lithium in the electrolyte is precipitated, and then filtered and separated. The obtained lithium carbonate has a purity of up to 99.6% after analysis. The single extraction rate of lithium in this method can reach 99.2%, which shows that this method can achieve rapid separation and collection of Li in the ternary positive electrode.

[0013] After separation and recovery of metallic lithium, the cathode and anode in the electrolytic cell are taken out, cleaned and dried respectively. The oxide obtained on the anode surface is MnO 2 , the purity of manganese oxide also reached 98%. After analysis, the single extraction rate of manganese can reach 95%, and a small amount of Mn remains in the electrolyte or is adsorbed in the cathode Ni-Co alloy. It can be seen that this method can also effectively separate the metal Mn in the ternary positive electrode. In this step, no precipitant or organic extractant is used to separate the metal Li, Mn, and Ni-Co from the retired ternary lithium battery positive electrode active materials. All aqueous solutions are used, which are low in cost and very safe, and are conducive to large-scale use in the industry.

[0014] Afterwards, the other electrode in step 3 is placed in the electrolytic cell as an anode. The cathode of the electrolytic cell can be a Pt or graphite electrode. The electrolyte in this step is a nickel sulfate aqueous solution with a concentration of 50 to 200 g / L. The electrolyte is adjusted to a pH of 7 to 8 using an alkaline solution, and the alkaline solution is a NaOH solution with a concentration of 0.01 to 1 M. Preferably, the concentration of the nickel sulfate aqueous solution can be 60 g / L, 80 g / L, 100 g / L, 120 g / L, 140 g / L, 160 g / L, 180 g / L, 190 g / L. High concentrations can achieve more efficient separation of nickel metal in the positive electrode material of the ternary lithium battery. The nickel sulfate electrolyte can be reused. When the nickel concentration in the electrolyte is lower than the lower limit, nickel sulfate needs to be appropriately supplemented so that the electrolyte concentration is maintained within the above range, which is convenient for the smooth separation and collection of metallic nickel in the positive electrode of the lithium battery. The electrolysis current density in step 4 is 20 to 100 A / m 2 , preferably 30A / m 2 , 40A / m 2 , 50A / m 2 、60A / m 2 , 70A / m 2 、80A / m 2 , 90A / m 2 . In order to facilitate the complete separation of nickel and cobalt, the current density should not be too large. After the electrolytic cell treatment, the anode and cathode are taken out, and the metal Co is obtained after the anode is cleaned and dried, and the metal Ni is obtained after the cathode is cleaned and dried. The purity of nickel and cobalt is measured to be more than 98%, and the single extraction rate of nickel and cobalt has reached 95%.

[0015] Preferably, the positive electrode material of the ternary lithium-ion battery is a nickel-cobalt-manganese ternary positive electrode, which can be a common nickel-cobalt-manganese ternary material, such as NCM532, NCM622, and NCM811.

[0016] It should be noted that the active material in the present invention refers to a material having an electrically active substance in a battery electrode.

[0017] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0018] First, the present application provides a method for recovering retired ternary lithium-ion battery positive electrode materials with simple operation, high leaching efficiency and industrial application. On the one hand, the present application can achieve a high level of recovery of each valuable metal in the ternary positive electrode material of the lithium-ion battery, and the product purity is high, which satisfies the separate utilization and classification of different metal elements in the ternary positive electrode material of the lithium battery, has a high economic value, and has a good effect on solving the retirement and scrapping of a large number of lithium-ion batteries, and has a good industrial value. On the second hand, the present application does not require high temperature and high pressure treatment, nor does it require repeated organic extraction or high energy consumption fire alloy. The whole method is simple, the energy consumption is low, and the effective separation of valuable metals in the ternary positive electrode of the lithium battery is achieved. On the third hand, although the electrochemical separation of lithium-ion battery positive electrode materials has been mentioned before, due to the close reduction potential of metal Ni and Co, few people currently use the electrolytic cell method to separate nickel and cobalt in one step. Most of them use organic complexation or precipitation or extraction to analyze nickel and cobalt ions, and then precipitate and separate the system containing a single valuable metal. The corresponding process will require multiple times, and the separation effect is not high. The invention effectively overcomes the technical prejudice that nickel and cobalt are generally difficult to separate by electrochemistry. The entire recovery method is simple to operate, does not require toxic and expensive extractants, reduces the consumption of chemical reagents, reduces recovery costs, and has high use value, economic value, and environmental value. DETAILED DESCRIPTION

[0019] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention are further described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0020] It should be noted that the terms "including" and "having" in the embodiments of the present application and any variations thereof are intended to cover non-exclusive inclusions.

[0021] Embodiment 1

[0022] A method for recovering ternary positive electrode materials for lithium-ion batteries, wherein the ternary positive electrode materials are obtained by discharging, disassembling, stripping active materials from current collectors, and crushing active positive electrode materials from retired lithium-ion batteries, wherein the discharge treatment is to immerse the lithium-ion battery in a saturated NaCl solution for 3 to 10 hours. The active material is stripped from the current collector by one of ultrasonic treatment, NMP dissolution, and alkaline solution treatment. The recovery method comprises the following steps: Step 1: The ternary positive electrode materials for lithium-ion batteries are crushed into powder and dissolved in 1.5M to 2.5M dilute sulfuric acid, and then a reducing agent hydrogen peroxide is added to the dilute sulfuric acid, wherein the concentration of hydrogen peroxide is 5 to 30 g / L, and after the reducing agent is added, the solid-liquid ratio of the ternary positive electrode materials to the sulfuric acid / reducing agent solution in the system is 50 g / L, and the dilute sulfuric acid solution is heated to 50 to 80°C by continuous stirring and reacted for 5 hours to obtain an acidified leaching solution; Step 2: The pH of the leaching solution is adjusted to 6, and then the leaching solution is used as an electrolyte at 100A / m 2 The electrolysis treatment is carried out at a current density of , the electrolytic cell electrode is a Pt electrode, stirring is continued during the electrolysis process, and the electrolysis time is 5h; Step 3: After the electrolysis is completed, the leachate is filtered, and an alkaline solution is added to the filtrate to adjust its pH to 8-11, and then excess sodium carbonate is added to precipitate lithium, and after the reaction, it is filtered and separated to obtain lithium carbonate; Step 4: The anode and cathode of the electrolytic cell are taken out, and the anode is cleaned and dried to obtain MnO 2 After cleaning and drying, the cathode is placed in an electrolytic cell as an anode. The electrolyte is a 200 g / L nickel sulfate solution with a pH of 7 adjusted with an alkaline solution. The cathode is a Pt or graphite electrode. 2 Electrolysis was performed at a current density of for 4 h, after which the anode and cathode of the electrolytic cell were taken out, and metal Co was obtained after the anode was cleaned and dried, and metal Ni was obtained after the cathode was cleaned and dried.

[0023] The single recovery rate of Li in this embodiment is calculated to be 99%, the purity of lithium carbonate is 99.6%, the single recovery rate of Mn is 96%, and the purity of MnO is 99.6%. 2 The purity of is 98%, the single recovery rate of Ni is 96% and the purity is 99%, and the single recovery rate of Co is 95% and the purity is 98%.

[0024] Embodiment 2

[0025] A method for recovering ternary positive electrode materials for lithium-ion batteries, wherein the ternary positive electrode materials are obtained by discharging, disassembling, stripping active materials from current collectors, and crushing active positive electrode materials from retired lithium-ion batteries, wherein the discharge treatment is to immerse the lithium-ion battery in a saturated NaCl solution for 3 to 10 hours. The active material is stripped from the current collector by one of ultrasonic treatment, NMP dissolution, and alkaline solution treatment. The recovery method comprises the following steps: Step 1: The ternary positive electrode materials for lithium-ion batteries are crushed into powder and dissolved in 1.5M to 2.5M dilute sulfuric acid, and then sodium sulfite, a reducing agent, is added to the dilute sulfuric acid, and the concentration of hydrogen peroxide is 5 to 30 g / L. After the reducing agent is added, the solid-liquid ratio of the ternary positive electrode material to the sulfuric acid / reducing agent solution in the system is 100 g / L, and the dilute sulfuric acid solution is heated to 50 to 80°C by continuous stirring and reacted for 10 hours to obtain an acidified leachate; Step 2: The pH of the leachate is adjusted to 3, and then the leachate is used as an electrolyte at 50A / m 2 The electrolysis treatment is carried out at a current density of , the electrolytic cell electrode is a Pt electrode, stirring is continued during the electrolysis process, and the electrolysis time is 8h; Step 3: After the electrolysis is completed, the leachate is filtered, and an alkaline solution is added to the filtrate to adjust its pH to 8-11, and then excess sodium carbonate is added to precipitate lithium, and after the reaction, it is filtered and separated to obtain lithium carbonate; Step 4: The anode and cathode of the electrolytic cell are taken out, and the anode is cleaned and dried to obtain MnO 2 After cleaning and drying, the cathode is placed in the electrolytic cell as the anode. The electrolyte is a 50 g / L nickel sulfate solution with an alkali solution adjusted to pH 8. The cathode is a Pt or graphite electrode at 20 A / m 2 Electrolysis was performed at a current density of for 8 h, after which the anode and cathode of the electrolytic cell were taken out, and metal Co was obtained after the anode was cleaned and dried, and metal Ni was obtained after the cathode was cleaned and dried.

[0026] The single recovery rate of Li in this embodiment is calculated to be 95%, the purity of lithium carbonate is 99%, the single recovery rate of Mn is 93%, and the purity of MnO is 99%. 2 The purity of is 95%, the single recovery rate of Ni is 95% and the purity is 98%, and the single recovery rate of Co is 95% and the purity is 97%.

[0027] Embodiment 3

[0028] A method for recovering ternary positive electrode materials for lithium-ion batteries, wherein the ternary positive electrode materials are obtained by discharging, disassembling, stripping active materials from current collectors, and crushing active positive electrode materials from retired lithium-ion batteries, wherein the discharge treatment is to immerse the lithium-ion battery in a saturated NaCl solution for 3 to 10 hours. The active material is stripped from the current collector by one of ultrasonic treatment, NMP dissolution, and alkaline solution treatment. The recovery method comprises the following steps: Step 1: The ternary positive electrode materials for lithium-ion batteries are crushed into powder and dissolved in 1.5M to 2.5M dilute sulfuric acid, and then sodium thiosulfate, a reducing agent, is added to the dilute sulfuric acid, and the concentration of hydrogen peroxide is 5 to 30 g / L. After the reducing agent is added, the solid-liquid ratio of the ternary positive electrode material to the sulfuric acid / reducing agent solution in the system is 200 g / L, and the dilute sulfuric acid solution is heated to 50 to 80°C by continuous stirring and reacted for 3 hours to obtain an acidified leaching solution; Step 2: The pH of the leaching solution is adjusted to 5, and then the leaching solution is used as an electrolyte at 10A / m 2 The electrolysis treatment is carried out at a current density of , the electrolytic cell electrode is a Pt electrode, stirring is continued during the electrolysis process, and the electrolysis time is 8h; Step 3: After the electrolysis is completed, the leachate is filtered, and an alkaline solution is added to the filtrate to adjust its pH to 8-11, and then excess sodium carbonate is added to precipitate lithium, and after the reaction, it is filtered and separated to obtain lithium carbonate; Step 4: The anode and cathode of the electrolytic cell are taken out, and the anode is cleaned and dried to obtain MnO 2 After cleaning and drying, the cathode is placed in the electrolytic cell as the anode. The electrolyte is a nickel sulfate solution with a concentration of 80 g / L and an alkaline solution adjusted to pH 7. The cathode is a Pt or graphite electrode at 50 A / m 2 Electrolysis was performed at a current density of for 6 h, after which the anode and cathode of the electrolytic cell were taken out, and metal Co was obtained after the anode was cleaned and dried, and metal Ni was obtained after the cathode was cleaned and dried.

[0029] The single recovery rate of Li in this embodiment is calculated to be 92%, the purity of lithium carbonate is 97%, the single recovery rate of Mn is 90%, and the purity of MnO is 97%. 2 The purity of is 97%, the single recovery rate of Ni is 92% and the purity is 99%, and the single recovery rate of Co is 90% and the purity is 92%.

[0030] Embodiment 4

[0031] A method for recovering ternary positive electrode materials for lithium-ion batteries, wherein the ternary positive electrode materials are obtained by discharging, disassembling, stripping active materials from current collectors, and crushing active positive electrode materials from retired lithium-ion batteries, wherein the discharge treatment is to immerse the lithium-ion battery in a saturated NaCl solution for 3 to 10 hours. The active material is stripped from the current collector by one of ultrasonic treatment, NMP dissolution, and alkaline solution treatment. The recovery method comprises the following steps: Step 1: The ternary positive electrode materials for lithium-ion batteries are crushed into powder and dissolved in 1.5M to 2.5M dilute sulfuric acid, and then a reducing agent hydrogen peroxide is added to the dilute sulfuric acid, wherein the concentration of hydrogen peroxide is 5 to 30 g / L, and after the reducing agent is added, the solid-liquid ratio of the ternary positive electrode materials to the sulfuric acid / reducing agent solution in the system is 60 g / L, and the dilute sulfuric acid solution is heated to 50 to 80°C by continuous stirring and reacted for 4 hours to obtain an acidified leaching solution; Step 2: The pH of the leaching solution is adjusted to 4, and then the leaching solution is used as an electrolyte at 80A / m 2 The electrolysis treatment is carried out at a current density of , the electrolytic cell electrode is a Pt electrode, stirring is continued during the electrolysis process, and the electrolysis time is 7h; Step 3: After the electrolysis is completed, the leachate is filtered, and an alkaline solution is added to the filtrate to adjust its pH to 8-11, and then excess sodium carbonate is added to precipitate lithium, and after the reaction, it is filtered and separated to obtain lithium carbonate; Step 4: The anode and cathode of the electrolytic cell are taken out, and the anode is cleaned and dried to obtain MnO 2 After cleaning and drying, the cathode is placed in the electrolytic cell as the anode. The electrolyte is a 150 g / L nickel sulfate solution with an alkali solution adjusted to pH 8. The cathode is a Pt or graphite electrode at 80 A / m 2 Electrolysis was performed at a current density of for 7 h, after which the anode and cathode of the electrolytic cell were taken out, and metal Co was obtained after the anode was cleaned and dried, and metal Ni was obtained after the cathode was cleaned and dried.

[0032] The single recovery rate of Li in this embodiment is calculated to be 96%, the purity of lithium carbonate is 98%, the single recovery rate of Mn is 94%, and the purity of MnO is 98%. 2 The purity of is 97%, the single recovery rate of Ni is 95% and the purity is 96%, and the single recovery rate of Co is 94% and the purity is 98%.

[0033] On this basis, the embodiment of the present application can realize the effective recycling of retired NCM ternary lithium battery positive electrode materials. The products of the recycling method are separated lithium carbonate, metallic nickel, metallic cobalt and MnO. 2, the product purity is high after measurement, and can be directly used as raw material for industrial use. In addition, the valuable metal recovery method of the NCM ternary positive electrode material can achieve a high level of recovery of valuable metals in the positive electrode material, and the basic recovery efficiency is above 90%. In addition, in order to further improve the recovery efficiency of valuable metals, the recovery process can also be repeated multiple times. It can be seen that the recovery method of the embodiment of the present application is simple in process and can achieve high-quality recovery of valuable metals in the ternary positive electrode material.

[0034] The above is a detailed introduction to a method for recycling a lithium-ion battery ternary positive electrode material disclosed in an embodiment of the present application. The above content is a further detailed description of the present invention in combination with a specific preferred embodiment, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, its architecture can be flexible and can derive a series of products. Just making a few simple deductions or substitutions should be regarded as belonging to the scope of patent protection of the present invention determined by the submitted claims.

Claims

1. A method for recycling ternary positive electrode materials for lithium-ion batteries, wherein the ternary positive electrode material is ternary nickel-cobalt-manganese oxide NCM, characterized in that: The steps include: Step 1: crush the lithium-ion battery ternary positive electrode material into powder and dissolve it in dilute sulfuric acid to form a solution 1, wherein the concentration of the dilute sulfuric acid is 1.5M to 2.5M, then add a reducing agent to the solution 1, the reducing agent is one of hydrogen peroxide, sodium thiosulfate, and sodium sulfite, continue stirring and heat the solution 1 to 50 to 80° C., react for 2 to 10 hours to obtain an acidified leaching solution; Step 2: Adjust the pH of the leaching solution to 3-6, and then use the leaching solution as an electrolyte at 10-100 A / m 2 The electrolysis treatment is carried out at a current density of , the electrolytic cell electrodes are Pt or graphite electrodes, stirring is continued during the electrolysis process, and the electrolysis time is 3 to 8 hours; Step 3: After the electrolysis is completed, the leachate is filtered, and an alkaline solution is added to the filtrate to adjust its pH to 8-11, and then an excess of sodium carbonate is added to carry out lithium precipitation reaction, and after the reaction, the lithium carbonate is obtained by filtration and separation; Step 4: Take out the cathode and cathode of the electrolytic cell, clean and dry the anode to obtain MnO2, clean and dry the cathode and put it into the electrolytic cell as the anode, the electrolyte is a 100g / L nickel sulfate solution with a pH of 7-8 adjusted by an alkaline solution, the cathode is a Pt or graphite electrode, and the 2 Electrolysis is carried out at a current density of 4 to 8 hours, after which the anode and cathode of the electrolytic cell are taken out, and metal Co is obtained after the anode is cleaned and dried, and metal Ni is obtained after the cathode is cleaned and dried.

2. A method for recycling ternary positive electrode materials for lithium-ion batteries according to claim 1, characterized in that: In step 1, the concentration of the dilute sulfuric acid is 2M, the concentration of the reducing agent is 5-30 g / L, the solid-liquid ratio of the ternary positive electrode material to the sulfuric acid / reducing agent solution is 50-200 g / L, and the stirring time is 3-6 hours.

3. A method for recycling ternary positive electrode materials for lithium-ion batteries according to claim 1, characterized in that: Before step 1, at least the lithium-ion battery is subjected to a discharge treatment, wherein the discharge treatment is to immerse the lithium-ion battery in a saturated NaCl solution for a discharge time of 3 to 10 hours.

4. A method for recycling ternary positive electrode materials for lithium-ion batteries according to claim 3, characterized in that: The lithium-ion battery is disassembled after being subjected to short-circuit discharge treatment, and then the ternary positive electrode material is separated from the current collector and crushed.

5. A method for recycling ternary positive electrode materials for lithium-ion batteries according to claim 1, characterized in that: In step 2, the pH of the leaching solution is 5, and the current density of the electrolysis treatment is 50A / m 2 The electrolytic cell electrode is a Pt electrode and the electrolysis time is 6h.

6. A method for recycling ternary positive electrode materials for lithium-ion batteries according to claim 1, characterized in that: In step 2, step 3 and step 4, the alkaline solution for adjusting pH is a NaOH solution with a concentration of 0.01 to 1 M.

7. A method for recycling ternary positive electrode materials for lithium-ion batteries according to claim 1, characterized in that: The ternary nickel cobalt lithium manganese oxide is NCM532, NCM622, or NCM811.