An alkaline recovery and regeneration process for waste ternary cathode materials

Abstract

The present invention belongs to the field of lithium-ion battery recycling, and specifically relates to an alkali method for recycling and regenerating waste ternary cathode materials. An alkali method for recycling and regenerating waste ternary cathode materials specifically comprises the following steps: the first-stage reduction alkali leaching treatment, solid-liquid separation, where lithium, nickel, cobalt and a small amount of manganese enter the liquid phase, and the manganese to be recovered and impurity elements such as aluminum, copper and iron enter the slag phase; the second-stage reduction alkali leaching treatment to realize the re-extraction process of manganese and enrich it in the liquid phase; mixing the leaching solutions of the two-stage alkali leaching, testing the metal ion concentration and the pH value; adjusting the pH to realize the coprecipitation process, and filtering and separating to obtain the cathode precursor material. In view of the different leaching conditions of lithium, nickel, cobalt and manganese in the alkali method system, the present invention designs a two-stage leaching process to realize the extraction and regeneration of valuable metals.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion battery recycling, and specifically relates to an alkali method for recycling and regenerating waste ternary cathode materials. Background Art

[0002] The rise and development of lithium-ion batteries are important components of the current new energy industry. However, the non-renewability of scarce metal resources poses requirements for the sustainable development of lithium-ion batteries, that is, the resource utilization of waste batteries.

[0003] Existing recycling processes have their own advantages and disadvantages. Among them, the alkali method process under the wet process system has attracted the attention of many researchers because of its metal selectivity, which can reduce the advantages of the impurity separation process. In the common alkali method process, the main recycling targets are three elements with higher values, namely lithium, nickel, and cobalt, while manganese enters the slag phase. For example, Chinese authorized patent 202010542346.X discloses a method for recycling waste ternary lithium batteries, which uses an ammonia leaching process to extract lithium, nickel, and cobalt; another example is Chinese authorized patent 201811045199.4, which uses one-stage pressure ammonia leaching to extract lithium, nickel, and cobalt from waste ternary cathode materials, and two-stage atmospheric acid leaching to extract manganese and aluminum, and finally realizes the regeneration of ternary precursor materials. Obviously, there is a problem of low process efficiency in the extraction of manganese during the alkali method process, and the synchronous extraction of manganese with lithium, nickel, and cobalt cannot be achieved. This is mainly attributed to the fact that the optimal leaching conditions of manganese under the ammonia leaching process are different from those of lithium, nickel, and cobalt, resulting in the preferential leaching of lithium, nickel, and cobalt. Due to the leaching of lithium, nickel, and cobalt, the reaction conditions such as ammonia concentration in the system decrease, so that the leaching of manganese cannot be satisfied. More importantly, too high initial ammonia concentration will inhibit the leaching of lithium, nickel, and cobalt. Therefore, designing a two-stage leaching process is more conducive to the leaching and extraction of the four main elements of lithium, nickel, cobalt, and manganese. At the same time, the leaching solutions in the two-stage leaching process can be directly mixed, and using the characteristics that their chemical environment is similar to that of the precursor, the regeneration of the precursor material can be realized in one step, which not only shortens the process flow, but also realizes the closed-loop resource regeneration process of waste materials.

[0004] Therefore, in view of the problem of low manganese leaching rate during the alkali method process, this patent designs a two-stage alkali leaching process to extract the four main metals of lithium, nickel, cobalt, and manganese from waste ternary cathode materials and directly use them for the regeneration of precursor materials. Summary of the Invention

[0005] The technical problem solved by the present invention is: aiming at the recycling process of waste lithium-ion batteries, a method for recycling and regenerating waste ternary cathode materials by an alkali method is proposed. The four main metals are extracted by a two-stage leaching method and directly used for the regeneration of precursor materials, realizing the closed-loop recycling of waste ternary cathode materials.

[0006] The technical solution adopted by the present invention to solve its technical problems is:

[0007] The alkali recovery and regeneration process for waste ternary cathode materials includes the following steps:

[0008] (1) The first-stage reduction alkali leaching treatment. The leaching bottom solution is prepared with ammonia water, ammonium salt, water, and a reducing agent. After the bottom solution is heated, an appropriate amount of waste ternary cathode materials is added. After reacting for a period of time, filtration and separation are carried out to obtain the first-stage leaching solution and the first-stage leaching residue;

[0009] (2) The second-stage reduction alkali leaching treatment. The leaching bottom solution is prepared with ammonia water, ammonium salt, water, and a reducing agent. The first-stage leaching residue is added and reacted at room temperature. After reacting for a period of time, filtration and separation are carried out to obtain the second-stage leaching solution and the second-stage leaching residue;

[0010] (3) The first-stage leaching solution and the second-stage leaching solution are mixed. The metal concentration and pH value of the mixed solution are tested and analyzed. An appropriate amount of alkali solution is added to adjust the pH value. After reacting for a period of time, filtration and separation of the solid phase are carried out to obtain the precursor material.

[0011] Preferably, in step (1), the ammonia water concentration in the leaching bottom solution is 5 - 10 mol / L, the ammonium salt is one or more of ammonium chloride, ammonium sulfate, and ammonium carbonate, and the concentration is 1 - 5 mol / L. The reaction temperature is 30 - 80 °C, and the reaction time is 30 - 120 min.

[0012] Preferably, the reducing agent in step (1) is one or more of sodium sulfite and potassium sulfite. The usage amount of the reducing agent and the waste ternary cathode materials maintains a molar ratio of 1:1 - 2:1. At the same time, the addition amount of the waste ternary cathode materials satisfies a solid-liquid ratio of 1 - 20 g / L.

[0013] Preferably, in step (2), the ammonia water concentration in the leaching bottom solution is 10 - 20 mol / L, the ammonium salt is one or more of ammonium chloride, ammonium sulfate, and ammonium carbonate, and the concentration is 1 - 5 mol / L. The reaction time is 30 - 120 min.

[0014] Preferably, the reducing agent mentioned in step (2) is one or more of sodium sulfite and potassium sulfite.

[0015] Preferably, the alkali solution used to adjust the pH in step (3) is one or more of sodium hydroxide solution, potassium hydroxide solution, and ammonia water. The pH end point is between 10 - 10.5. The general formula of the precursor material is LiOH·Ni x Co y Mn 1-x-y (OH)2(0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ x + y ≤ 1).

[0016] [[ID=…]]The beneficial effects of the present invention are as follows:

[0017] The present invention provides an alkali recovery and regeneration process for waste ternary cathode materials, which improves the recovery rate of manganese by means of two-stage leaching; at the same time, taking advantage of the characteristic that the composition of the leaching solution is similar to that of the precursor synthesis solution obtained by the alkali leaching process, the direct regeneration of the precursor can be achieved by simply adjusting the pH. By adding a second-stage alkali leaching process, the deficiencies of the first-stage alkali leaching process are compensated, and the utilization of each component of the waste ternary cathode material is realized to a greater extent. It is expected to achieve a closed-loop recycling of all components and alleviate the development constraints caused by the shortage of scarce metal resources. Brief Description of the Drawings

[0018] Figure 1 is the process flow chart adopted by the present invention;

[0019] Figure 2 is the scanning electron microscope image of the regenerated cathode product in Example 1 of the present invention. Detailed Embodiments

[0020] The present invention will be further described below in conjunction with the embodiments and the drawings.

[0021] Example 1

[0022] (1) The first-stage reduction alkali leaching treatment, where the total volume of the leaching bottom liquid is 200 mL, the ammonia water concentration is 10 mol / L, the ammonium sulfate concentration is 4 mol / L. After mixing evenly, the temperature is raised to 60 °C, and then 1 g of waste ternary cathode material and 1.3 g of Na2SO3 are added and reacted fully for 60 min. After filtration and separation, the first-stage leaching solution and the first-stage leaching residue are obtained.

[0023] (2) The second-stage reduction alkali leaching treatment, where the total volume of the leaching bottom liquid is 200 mL, the ammonia water concentration is 15 mol / L, the ammonium carbonate concentration is 3 mol / L. All of the first-stage leaching residue is added, as well as an additional 1.3 g of Na2SO3, and the reaction is carried out at room temperature for 60 min. After filtration and separation, the second-stage leaching solution and the second-stage leaching residue are obtained.

[0024] (3) Mix the first-stage leaching solution and the second-stage leaching solution, add water to make the total volume 500 mL, detect the metal concentration and pH value in the solution, appropriately add metal ions to make the molar ratio Li:Ni:Co:Mn = 10:3.33:3.33:3.33, and then slowly adjust the pH value to 10.8 with 5 mol / L sodium hydroxide solution, and filter to collect the precipitate.

[0025] Analysis of the first-stage leaching solution by ICP testing and calculation shows that enrichment of Li at 96.9%, Ni at 98.1%, Co at 93.6%, and Mn at 37.7% was achieved, while Fe, Al, and Cu did not enter the filtrate. Analysis of the second-stage leaching solution by ICP testing and calculation shows that increasing the ammonia concentration in the second-stage alkaline leaching can achieve enrichment and extraction of more than 90% of the remaining Mn. Finally, slowly adjust the pH value to 10.8 to obtain relatively uniform precursor particles, the morphology of which is as Figure 2 shown.

[0026] Example 2

[0027] (1) First-stage reduction alkaline leaching treatment, where the total volume of the leaching bottom liquid is 200 mL, the ammonia water concentration is 10 mol / L, the ammonium chloride concentration is 2 mol / L. After mixing evenly, heat up to 70 °C, then add 2 g of waste ternary cathode material and 1 g of N2H4·H2O and react fully for 60 min. Filter and separate to obtain the first-stage leaching solution and the first-stage leaching residue.

[0028] (2) Second-stage reduction alkaline leaching treatment, where the total volume of the leaching bottom liquid is 200 mL, the ammonia water concentration is 16 mol / L, the ammonium carbonate concentration is 2 mol / L. Add all of the first-stage leaching residue, as well as an additional 1 g of N2H4·H2O, and react at room temperature for 60 min. Filter and separate to obtain the second-stage leaching solution and the second-stage leaching residue.

[0029] (3) Mix the first-stage leaching solution and the second-stage leaching solution, add water to make the total volume 500 mL, detect the metal concentration and pH value in the solution, appropriately add metal ions to make the molar ratio Li:Ni:Co:Mn = 10:5:2:3, and then slowly adjust the pH value to 10.5 with 10 mol / L ammonia water, and filter to collect the precipitate.

[0030] Example 3

[0031] (1) First-stage reduction alkaline leaching treatment, where the total volume of the leaching bottom liquid is 200 mL, the ammonia water concentration is 10 mol / L, the ammonium chloride concentration is 2 mol / L. After mixing evenly, heat up to 80 °C, then add 3 g of waste ternary cathode material and 2 g of N2H4·H2O and react fully for 60 min. Filter and separate to obtain the first-stage leaching solution and the first-stage leaching residue.

[0032] (2) Second-stage reduction alkaline leaching treatment, where the total volume of the leaching bottom liquid is 200 mL, the ammonia water concentration is 16 mol / L, the ammonium carbonate concentration is 2 mol / L. Add all of the first-stage leaching residue, as well as an additional 2 g of N2H4·H2O, and react at room temperature for 60 min. Filter and separate to obtain the second-stage leaching solution and the second-stage leaching residue.

[0033] (3) Mix the first-stage leaching solution and the second-stage leaching solution, add water to make the total volume 500 mL, detect the metal concentration and pH value in the solution, appropriately add metal ions to make the molar ratio Li:Ni:Co:Mn = 10:3.33:3.33:3.33, and then slowly adjust the pH value to 10.8 with 8 mol / L ammonia water, and filter to collect the precipitate.

Claims

1. An alkaline recovery and regeneration process for waste ternary cathode materials, characterized in that: The following steps are involved: (1) The first stage is a reduction alkaline leaching treatment. The leaching bottom liquid is prepared by ammonia water, ammonium salt, water and a reducing agent. After the bottom liquid is heated, an appropriate amount of waste ternary cathode material is added. After a period of reaction, the leaching liquid and the leaching residue are separated by filtration. (2) The second stage of reduction alkaline leaching treatment, the configuration of the leaching bottom liquid is ammonia water, ammonium salt, water and reducing agent, the first stage leaching residue is added and reacted at room temperature, after a period of reaction, the second stage leaching liquid and the second stage leaching residue are obtained by filtration and separation; (3) The first-stage leachate and the second-stage leachate are mixed, the metal concentration and pH value of the mixed solution are tested and analyzed, an appropriate amount of alkaline solution is added to adjust the pH value, and after a period of reaction, the solid phase is filtered and separated to obtain the precursor material; In step (1), the concentration of the leaching bottom liquid ammonia is 5 to 10 mol / L, the ammonium salt is one or more of ammonium chloride, ammonium sulfate and ammonium carbonate, and the concentration is 1 to 5 mol / L, the reaction temperature is 30 to 80° C., and the reaction time is 30 to 120 min; the reducing agent in step (1) is one or both of sodium sulfite and potassium sulfite, and the molar ratio of the reducing agent to the waste ternary positive electrode material is maintained at 1:1 to 2:1, and the amount of the waste ternary positive electrode material added satisfies the solid-liquid ratio of 1 to 20 g / L; The ammonia concentration of the leaching bottom liquid in step (2) is 10-20 mol / L, the ammonium salt is one or more of ammonium chloride, ammonium sulfate and ammonium carbonate, and the concentration is 1-5 mol / L, and the reaction time is 30-120 min; the reducing agent mentioned in step (2) is one or both of sodium sulfite and potassium sulfite.

2. The alkaline recovery and regeneration process for waste ternary cathode materials according to any one of claim 1, characterized in that: The alkaline solution used to adjust the pH in step (3) is one or more of sodium hydroxide solution, potassium hydroxide solution, and ammonia water. The pH end point is between 10 and 10.

5. The chemical formula of the precursor material is LiOH·Ni x Co y Mn 1-x-y (OH)2, where 0≤x≤1, 0≤y≤1, 0≤x+y≤1.

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