Recycling method for mixed waste material of lithium oxide, nickel, manganese and cobalt and lithium iron phosphate

Abstract

This description outlines a recycling method for a mixed waste material of lithium nickel manganese cobalt oxide (LNMCO) and lithium iron phosphate (LFP), comprising: carrying out acid leaching to obtain an acid leach liquor containing nickel, cobalt, manganese, phosphorus, iron, and lithium; carrying out adsorption separation with a resin, washing the resin with sulfuric acid to obtain a mixed solution of nickel sulfate, cobalt sulfate, and manganese sulfate, and subjecting the mixed solution to precipitation to obtain an LNMCO cathode material precursor; and subjecting the resulting solution containing phosphorus, iron, and lithium to lithium precipitation to obtain a lithium salt precipitate, and subjecting a post-precipitation solution to concentration and electrospinning to obtain a ferric phosphate / carbon material.The process described herein can achieve the comprehensive recycling of mixed LNMCO and LFP waste material and the targeted circulation of waste LNMCO and LFP materials. Furthermore, the preparation of ferric phosphate by electrospinning can reduce agglomeration in the material, and the resulting material has a fiber network structure, which can increase the specific surface area (ASE) of the material, thus improving its surface performance.

Description

Recycling method for mixed waste material of lithium oxide, nickel, manganese and cobalt and lithium iron phosphate TECHNICAL FIELD The present description belongs to the technical field of recycling waste battery materials, and refers specifically to a recycling method for a mixed waste material of lithium nickel manganese cobalt oxide (LNMCO) and lithium iron phosphate (LFP). BACKGROUND Lithium batteries with LNMCO as the cathode material have many advantages, such as high energy density, outstanding cycle performance, high voltage plateau, and a wide operating temperature range. Lithium batteries with LFP as the cathode material have excellent safety and cycle performance, making them widely used in the new energy field. With the rapid growth in lithium-ion battery (LIB) consumption, the amount of discarded LIBs has increased rapidly in recent years. In LNMCO batteries, nickel, cobalt, manganese, and lithium have a high recovery value. In LFP batteries, while the recovery value of phosphorus and iron is not high, these elements will cause environmental pollution if not properly treated.Therefore, recycling various battery materials can save production costs for companies, promote the healthy development of the new energy industry, and reduce pollution from waste battery materials in the environment. Currently, recycling methods for waste lithium iron ions (LIBs) primarily include pyrolysis and wet leaching. A hydrometallurgical recycling method has attracted considerable attention due to its advantages, such as high recovery efficiency and a simple procedure. Existing methods mainly target cathode and anode materials from waste LIBs. The related technique describes a comprehensive recycling method for a ternary cathode material from waste LIBs, in which nickel-lithium and manganese-cobalt are leached by alkaline and acid leaching, followed by gradual separation of nickel, cobalt, manganese, and lithium, thus achieving the separate recovery of each element. This method offers advantages such as high recovery selectivity, environmental friendliness, and a high recovery rate.However, a suspension obtained after alkaline leaching is difficult to filter, which can lead to incomplete separation and impure products; and a separation procedure is relatively cumbersome. The related technique also describes a recycling method, in which a waste ternary positive electrode sheet is baked, dissolved in water, and filtered to obtain a powder containing nickel, cobalt, manganese, and lithium. The LNMCO powder is then baked, dissolved, mixed with a potassium carbonate solution, and filtered to obtain a filter residue. A carbonate is added to the filter residue to adjust the ratio of lithium, nickel, cobalt, and manganese, and the resulting mixture is ball-milled, compacted, and baked to obtain an LNMCO cathode material.This method can regenerate waste LNMCO cathode material, which is beneficial for resource conservation, cost reduction, and environmental protection. However, high-temperature reduction baking involves high energy consumption and has significant equipment and personnel requirements, resulting in difficult industrialization. For LFP material recycling, lithium carbonate and phosphorus-iron compounds are traditionally prepared through smelting and recycling. This method results in the waste of phosphorus and iron resources and environmental pollution. Alternatively, the coprecipitation method can also be adopted.For example, waste LFP material is dissolved in an acid to obtain a mixed solution containing lithium ions, ferrous ions, and phosphate ions. The concentration of each ion and the pH are then adjusted to achieve coprecipitation of lithium, iron, and phosphorus, resulting in LFP material. However, the purity and yield of the LFP material obtained by this method need improvement. Additionally, there is a method in which lithium carbonate is added to waste LFP material, and the resulting mixture is sintered and reworked to obtain new LFP material. This method has stringent requirements regarding the morphology and composition of the waste material and has limited applicability.Furthermore, most of the methods for treating a waste LNMCO material or a waste LFP material currently disclosed only target one of the two waste materials, and there are very few methods that can treat a mixed waste material of the two. Therefore, there is an urgent need to develop a simple and environmentally friendly procedure that can recycle a mixed waste material from LNMCO and LFP. SUMMARY OF THE INVENTION This description is intended to solve at least one of the technical problems existing in the prior art. In view of this, the present description provides a simple and environmentally friendly recycling method for mixed LNMCO and LFP waste material that can achieve the recovery of all the main elements in the mixed waste material and its corresponding commercialization, and which has promising application prospects. According to one aspect of the present description, a recycling method for mixed LNMCO and LFP waste material is provided, which includes the following steps: S1: Add the mixed waste material from LNMCO and LFP to an acidic solution for acid leaching, and carry out solid-liquid separation (SSL) to obtain an acid leach liquor; S2: Use a resin to adsorb nickel, cobalt, and manganese in the acid leaching liquor, and wash the resulting saturated resin with sulfuric acid to obtain a mixed solution of nickel sulfate, cobalt sulfate, and manganese sulfate, and a post-adsorption solution; S3: Heat the post-adsorption solution, and add a lithium precipitating reagent to obtain a lithium salt precipitate and a post-precipitation solution; and S4: Concentrate the post-precipitation solution, add a carbon source, and stir the resulting mixture to obtain a dispersed mixture; and subject the dispersed mixture to electrospinning to obtain a sheet material, and dry and bake the sheet material to obtain a ferric phosphate / carbon material. In some implementations of this description, in S1, the acid solution may be one or more of the group consisting of sulfuric acid, nitric acid, and hydrochloric acid. Preferably, the acid solution may be a combination of sulfuric acid and hydrochloric acid, or a combination of sulfuric acid and nitric acid. In some implementations of the present description, in S1, the acid solution may have a concentration of 1 mol / l to 8 mol / l, and preferably 1.5 mol / l to 5 mol / l. In some implementations of the present description, in S1, a mass ratio of the acid solution to the mixed waste material may be (4-10) :1, and preferably (5-8) :1. In some implementations of the present description, in S1, acid leaching can be carried out at a temperature of 50°C to 120°C, and preferably 60°C to 90°C; and acid leaching can be carried out for 3 to 10 h, and preferably 4 to 8 h. In some implementations of the present description, in S2, the resin may be one or more of the group consisting of chelating resin XFS4195, AmberlitelRC748, LonacSR-5, PuroliteS-930, Chelex100, D851, and D402-E. Resin adsorption principle: The functional groups of multiple ligands in the resin polymer form complexes with metal ions to achieve separation. In some implementations of the present description, in S2, absorption can be carried out in a single-stage adsorption mode or multi-stage adsorption, which has high applicability and leads to a prominent effect. In some implementations of the present description, in S2, the mixed solution obtained from nickel sulfate, cobalt sulfate, and manganese sulfate may be precipitated to obtain a ternary precursor. In some implementations of the present description, in S3, the lithium precipitating reagent may be one or more of the group consisting of sodium carbonate, sodium phosphate, potassium phosphate, potassium carbonate, sodium oxalate, potassium oxalate, sodium fluoride, potassium fluoride, and ammonium fluoride; and heating may be carried out at 40°C to 120°C, and preferably 65°C to 100°C. In some implementations of the present description, in S4, the post-precipitation solution can be concentrated until the iron concentration in the post-precipitation solution is 40 g / l to 150 g / l, and preferably 50 g / l to 100 g / l. If the phosphorus and iron concentrations in the solution are too low, it is not easy to form filaments during spinning; and if the phosphorus and iron concentrations are too high, the needle will block or spindle will form. In some implementations of the present description, in S4, the carbon source may be one or more of the group consisting of polyvinylpyrrolidone (PVP), polyvinylidene fluoride (PVDF), and polyacrylonitrile (PAN). In some implementations of the present description, in S4, the carbon source is first dissolved in dimethylformamide (DMF), then the resulting solution is poured into a concentrated post-precipitation solution, and the resulting mixture is stirred to obtain a dispersed mixture. After electrospinning, the DMF is volatilized at low temperature, and then high-temperature baking is carried out to decompose the organic matter into a carbon material. In some implementations of this description, in S4, drying can be carried out at 40°C to 90°C, and preferably 40°C to 70°C. The heating rate should not be too high; otherwise, the filamentous texture will collapse. In some implementations of the present description, in S4, baking can be carried out at a temperature from 250°C to 600°C, and preferably from 300°C to 550°C, in an atmosphere of air or oxygen. According to a preferred implementation of this description, this description has at least the following beneficial effects: 1. The procedure described herein can achieve comprehensive recycling of a mixed LNMCO and LFP waste material. In the procedure, acid leaching is carried out to obtain an acid leach liquor containing nickel, cobalt, manganese, phosphorus, iron, and lithium; adsorption separation is performed using a resin; the resin is washed with sulfuric acid to obtain a mixed solution of nickel sulfate, cobalt sulfate, and manganese sulfate; this mixed solution is precipitated to obtain a precursor for LNMCO cathode material; and a solution obtained containing phosphorus, iron, and lithium is subjected to lithium precipitation to obtain a lithium salt precipitate; the post-precipitation solution is then concentrated and electrospun to obtain a ferric phosphate / carbon material, thus achieving the directed circulation of LNMCO and LFP waste materials. 2. The electrospinning preparation of ferric phosphate, as described herein, can reduce agglomeration in the material. The prepared material has a fiber network structure, which can increase the specific surface area (SSA) of the material, thus improving its surface performance. Compared to ferric phosphate material, ferric phosphate / carbon material has improved electrical conductivity and activity due to the carbon doping, which is beneficial for the growth of the LFP material in the subsequent baking process. 3. The procedure described herein is simple and environmentally friendly, has few equipment requirements, and provides great economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS The present description is further described below with reference to the accompanying drawings and examples. FIG. 1 is a procedure flowchart for Example 1 of this description. DETAILED DESCRIPTION OF ILLUSTRATED EXAMPLES The technical concepts and effects of this description are clearly and completely described below, along with examples, to enable a full understanding of its objectives, features, and effects. The examples described herein are merely a few of the many examples provided. All other examples obtained by a person skilled in the art, based on the examples in this description without creative effort, should fall within the scope of protection of this description. Example 1 A recycling method was provided for a mixed waste material from LNMCO and LFP, and as shown in FIG. 1, a specific procedure was as follows: (1) A waste material from LNMCO and a waste material from LFP were mixed, crushed and sieved to obtain a mixed waste material from LNMCO and LFP. (2) 50 g of the mixed LNMCO and LFP waste material obtained in step (1) were weighed and added to 250 ml of a sulfuric acid solution with a concentration of 2.5 mol / l in a beaker, then the beaker was placed in a water bath at 80°C, stirring was carried out for 4 h, and the resulting suspension was filtered to obtain a solution containing nickel, cobalt, manganese, phosphorus, iron, and lithium and a graphite residue. (3) A CH-90Na chelating resin was packed into a column, and the solution containing nickel, cobalt, manganese, phosphorus, iron, and lithium obtained in step (2) was added dropwise to the resin column using a peristaltic pump; after the resin reached adsorption saturation, a small amount of lithium adhering to the surface of the resin was washed off with pure water, and then the saturated resin was washed with a 1.5 mol / l sulfuric acid solution to obtain a mixed solution of nickel sulfate, cobalt sulfate, and manganese sulfate, wherein a post-adsorption solution was a solution containing phosphorus, iron, and lithium. (4) The mixed solution of nickel sulfate, cobalt sulfate, and manganese sulfate obtained in step (3) was subjected to precipitation to obtain a ternary precursor. (5) The solution containing phosphorus, iron, and lithium was heated to 90°C, a solution of sodium carbonate was added dropwise for the precipitation of lithium, and the resulting mixture was filtered to obtain a filter residue; the filter residue was washed with pure water and dried in an oven for 8 h to obtain lithium carbonate; and the lithium content in a lithium post-precipitation solution was determined, and the lithium recovery rate was calculated. (6) The lithium post-precipitation solution obtained in step (5) was concentrated to an iron concentration of 75 g / l; PVP was dissolved in DMF, the resulting solution was poured into the lithium post-precipitation solution, and the resulting mixture was subjected to dispersion; and electrospinning was carried out to obtain a sheet material, and the sheet material was dried at 60°C and then baked at 500°C to obtain a ferric phosphate / carbon material. Table 1 Calculation results for each component in Example 1 Example 2 A recycling method was provided for a mixed waste material from LNMCO and LFP, and a specific procedure was as follows: (1) A waste material from LNMCO and a waste material from LFP were mixed, crushed and sieved to obtain a mixed waste material from LNMCO and LFP. (2) 50 g of the mixed LNMCO and LFP waste material obtained in step (1) were weighed and added to 250 ml of a sulfuric acid and nitric acid solution having a concentration of 3.5 mol / l in a beaker. The beaker was then placed in a water bath heated to 90°C, stirring was carried out for 4 h, and the resulting suspension was filtered to obtain a solution containing nickel, cobalt, manganese, phosphorus, iron, and lithium and a graphite residue. (3) A CH-90Na chelating resin was packed into a column, and the solution containing nickel, cobalt, manganese, phosphorus, iron, and lithium obtained in step (2) was added dropwise to the resin column using a peristaltic pump; after the resin reached adsorption saturation, the post-adsorption solution was passed through a PuroliteS-930 resin column, a small amount of lithium adhering to the surface of the resin was washed off with pure water, and then the saturated resin was washed with a 1.5 mol / l sulfuric acid solution to obtain a mixed solution of nickel sulfate, cobalt sulfate, and manganese sulfate, wherein a post-adsorption solution was a solution containing phosphorus, iron, and lithium. (4) The mixed solution of nickel sulfate, cobalt sulfate, and manganese sulfate obtained in step (3) was subjected to precipitation to obtain a ternary precursor. (5) The solution containing phosphorus, iron, and lithium was heated to 80°C, a potassium carbonate solution was added dropwise for the precipitation of lithium, and the resulting mixture was filtered to obtain a filter residue; the filter residue was washed with pure water and dried in an oven for 8 h to obtain lithium carbonate; and the lithium content in a lithium post-precipitation solution was determined, and the lithium recovery rate was calculated. (6) The lithium post-precipitation solution obtained in step (5) was concentrated to an iron concentration of 80 g / l; PVDF was dissolved in DMF, the resulting solution was poured into the lithium post-precipitation solution, and the resulting mixture was subjected to dispersion; and electrospinning was carried out to obtain a sheet material, and the sheet material was dried at 60°C and then baked at 450°C to obtain a ferric phosphate / carbon material. Table 2 Calculation results for each component in Example 2 Example 3 A recycling method was provided for a mixed waste material from LNMCO and LFP, and a specific procedure was as follows: (1) A waste material from LNMCO and a waste material from LFP were mixed, crushed and sieved to obtain a mixed waste material from LNMCO and LFP. (2) 50 g of the mixed LNMCO and LFP waste material obtained in step (1) were weighed and added to 250 ml of a hydrochloric acid solution with a concentration of 4 mol / l in a beaker, then the beaker was placed in a water bath heated to 80°C, stirring was carried out for 6 h, and the resulting suspension was filtered to obtain a solution containing nickel, cobalt, manganese, phosphorus, iron, and lithium and a graphite residue. (3) A CH-90Na chelating resin was packed into a column, and the solution containing nickel, cobalt, manganese, phosphorus, iron, and lithium obtained in step (2) was added dropwise to the resin column using a peristaltic pump; after the resin reached adsorption saturation, the post-adsorption solution was passed through a D851 resin column, a small amount of lithium adhering to the surface of the resin was washed off with pure water, and then the saturated resin was washed with a 1.5 mol / l sulfuric acid solution to obtain a mixed solution of nickel sulfate, cobalt sulfate, and manganese sulfate, wherein a post-adsorption solution was a solution containing phosphorus, iron, and lithium. (4) The mixed solution of nickel sulfate, cobalt sulfate, and manganese sulfate obtained in step (3) was subjected to precipitation to obtain a ternary precursor. (5) The solution containing phosphorus, iron, and lithium was heated to 90°C, a solution of sodium carbonate was added dropwise for the precipitation of lithium, and the resulting mixture was filtered to obtain a filter residue; the filter residue was washed with pure water and dried in an oven for 8 h to obtain lithium carbonate; and the lithium content in a lithium post-precipitation solution was determined, and the lithium recovery rate was calculated. (6) The lithium post-precipitation solution obtained in step (5) was concentrated to an iron concentration of 75 g / l; PVP was dissolved in DMF, the resulting solution was poured into the lithium post-precipitation solution, and the resulting mixture was subjected to dispersion; and electrospinning was carried out to obtain a sheet material, and the sheet material was dried at 60°C and then baked at 400°C to obtain a ferric phosphate / carbon material. Table 3 Calculation results for each component in Example 3 This description is detailed with reference to the accompanying drawings and examples, but it is not limited to them. Within the scope of knowledge of those with normal expertise in the technical field, various changes may be made without departing from the purpose of this description. Furthermore, the examples in this description, or the features in the examples, may be combined without conflict.

Claims

1. A recycling method for a mixed waste material of lithium, nickel, manganese, and cobalt oxide and lithium iron phosphate, comprising the following steps: S1: adding the mixed waste material of lithium, nickel, manganese, and cobalt oxide and lithium iron phosphate to an acidic solution for acid leaching, and carrying out solid-liquid separation to obtain an acid leach liquor; S2: using a resin to adsorb nickel, cobalt, and manganese in the acid leach liquor, and washing the resulting saturated resin with sulfuric acid to obtain a mixed solution of nickel sulfate, cobalt sulfate, and manganese sulfate, and a post-adsorption solution; S3: heating the post-adsorption solution, and adding a lithium precipitating reagent to obtain a lithium salt precipitate and a post-precipitation solution; and S4: concentrate the post-precipitation solution, add a carbon source,and stirring to obtain a dispersed mixture; and subjecting the dispersed mixture to electrospinning to obtain a sheet material, and drying and baking the sheet material to obtain a ferric phosphate / carbon material.

2. The recycling method according to claim 1, wherein, in S1, the acid solution is one or more selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid.

3. The recycling method according to claim 1, wherein, in S1, the mass ratio of the acid solution to the mixed waste material is (4-10) :

1.

4. The recycling method according to claim 1, wherein, in S2, the resin is one or more selected from the group consisting of CH-90Na chelating resin, XFS4195 resin, AmberlitelRC748, LonacSR-5, PuroliteS-930, Chelex100, D851, and D402-E.

5. The recycling method according to claim 1, wherein, in S2, the mixed solution obtained from nickel sulfate, cobalt sulfate,and manganese sulfate is subjected to precipitation to obtain a ternary precursor.

6. The recycling method according to claim 1, wherein, in S3, the lithium precipitating reagent is one or more selected from the group consisting of sodium carbonate, sodium phosphate, potassium phosphate, potassium carbonate, sodium oxalate, potassium oxalate, sodium fluoride, potassium fluoride, and ammonium fluoride; and heating is carried out from 40°C to 120°C.

7. The recycling method according to claim 1, wherein, in S4, the post-precipitation solution is concentrated until the iron concentration in the post-precipitation solution is 40 g / L to 150 g / L.

8. The recycling method according to claim 1, wherein, at S4, the carbon source is one or more selected from the group consisting of polyvinylpyrrolidone, polyvinylidene fluoride, and polyacrylonitrile.

9. The recycling method according to claim 1, wherein, at S4,The carbon source is first dissolved in dimethylformamide to obtain a solution, then the solution is poured into a concentrated post-precipitation solution, and the resulting mixture is stirred to obtain the dispersed mixture.

10. The recycling method according to claim 1, wherein, in S4, drying is carried out at 40°C to 90°C; and baking is carried out at 250°C to 600°C.

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