Method for purifying lithium in waste lithium ion battery

Abstract

The invention discloses a method for purifying lithium in a waste lithium ion battery. The lithium in a waste lithium ion battery material is extracted by adopting an electrodialysis / complex reaction combined method. The method comprises the following steps: by taking a positive plate of a waste lithium ion battery as an anode plate, simultaneously adding ethylenediamine tetraacetic acid and electrolyte into an anode chamber, and after electrodialysis is carried out for a certain time, leaching lithium from the positive plate and transferring the lithium into a cathode chamber through an electrodialysis membrane; and leading out the slurry from the anode chamber, filtering, adding an acid solution into the filtrate, filtering again after a precipitate is generated, collecting filter residues, and returning to the anode chamber for reuse. According to the method, lithium in the waste lithium ion battery material is separated from other metals, and the obtained lithium-containing solution is high in purity and can be directly used for preparing high-purity lithium salt; meanwhile, aluminum is recycled in the form of metal foil, and other metals in the battery material enter the electrolytic slag. The method has the advantages of low cost and simplicity in operation.

Description

Technical Field

[0001] The invention relates to the technical field of recycling waste lithium-ion batteries, in particular to a method for purifying lithium in waste lithium-ion batteries. Background Art

[0002] Lithium-ion batteries have been widely used in various electronic devices in recent years due to their high energy density, long service life, and good stability. A large number of applications will inevitably lead to the generation of a large number of waste lithium-ion batteries. If they are not effectively recycled, they will have a huge impact on resources and human social life. For example, the plastic components and toxic electrolytes in the batteries will cause harmful soil pollution, and the loss of a large amount of valuable metals in waste lithium-ion batteries will lead to a shortage of natural resources. Therefore, the recycling of waste lithium-ion batteries has attracted widespread attention.

[0003] Valuable metals in waste positive plates have become the focus of researchers and companies due to their high added value. There are two methods for recovering lithium from waste lithium-ion batteries: priority lithium extraction and terminal lithium extraction. The terminal lithium extraction technology has a long process and each step such as precipitation and extraction will cause lithium loss, so the lithium recovery rate is very low (usually less than 85%); priority lithium extraction will not cause lithium loss, but the existing carbon thermal reduction technology still has the defect of low lithium recovery rate (usually less than 90%).

[0004] Electrochemical lithium extraction is one of the preferred methods for lithium extraction, with a high lithium recovery rate (which can be higher than 95%). For example, the "Method for Separating Aluminum Foil and Positive Electrode Active Material in Waste Lithium-ion Battery Positive Electrode Sheet" with publication number CN109659642A adopts electrochemical preferential lithium extraction technology, which can preferentially leach lithium into the electrolyte, and the lithium recovery rate can reach more than 95%. Using this method, only a small amount of other metals in the battery material are leached, and most of them remain in the positive electrode waste. However, since a small amount of other leached metal ions coexist with lithium ions in the electrolyte, the purity of the resulting lithium-containing solution is reduced, usually less than 99%, and cannot be directly used for the subsequent preparation of high-purity lithium salts such as lithium carbonate and lithium hydroxide. If the extracted lithium is to be used directly in the production of high-purity lithium salts (such as battery-grade lithium carbonate, etc.), it is also necessary to separate a small amount of other leached metal ions from lithium and transfer them out of the electrolyte.

[0005] Current technologies for lithium extraction by electrolysis have not been able to solve the problem of separating lithium from other small amounts of metals in the electrolyte. Therefore, it is still necessary to find a method to completely separate and recover lithium from other metals in the electrolyte. Summary of the invention

[0006] The present invention aims to solve the problem that the lithium recovery rate of the existing lithium extraction technology is low or the purity of the extracted lithium is not high, and provides a method for purifying lithium from waste lithium ion batteries. The method combines electrodialysis with metal complexation to achieve complete leaching of lithium from the positive electrode of the waste battery and complete separation from a small amount of leached metal ions to obtain a solution for preparing high-purity lithium salts.

[0007] A method for purifying lithium from waste lithium-ion batteries comprises the following steps: (1) After disassembling the waste lithium-ion batteries, collect the positive electrode sheets therein, use the waste positive electrode sheets as anode plates, and use plates such as stainless steel plates, titanium plates or graphite plates as cathode plates. The two plates are connected to the positive and negative electrodes of a power source through wires and then placed in the anode chamber and cathode chamber of an electrodialysis cell; A cation exchange membrane is installed between the anode chamber and the cathode chamber, and water or alkaline solution is injected into the cathode chamber; Install a stirrer in the anode chamber, inject electrolyte, and then add ethylenediaminetetraacetic acid, the amount of ethylenediaminetetraacetic acid added is 0.01-2g / 100ml electrolyte; (2) Start the power supply and electrolyze for 0.1-3h at a voltage of 5-35V; Then start the stirrer, and continue electrolysis for 0.1-4h at a voltage of 5-35V and a stirring speed of 10-500r / min, until all lithium is leached from the positive electrode into the electrolyte, and then turn off the power supply and stirrer; The liquid in the cathode chamber is drawn out and sent to the subsequent high-purity lithium salt preparation process; (3) Leading the slurry in the anode chamber to the filtering device, collecting the filter residue, and sending it to the subsequent recovery process of other metals; collecting the filtrate and proceeding to step (4); (4) introducing the filtrate obtained in step (3) into a stirred kettle containing 0.1-5 mol / L acid solution, stirring and reacting for 0.1-5 h at a temperature of 10-60° C. and a rotation speed of 10-500 r / min, filtering the obtained slurry, collecting the filter residue, and obtaining ethylenediaminetetraacetic acid, which is returned to step (1) for repeated use; The filtrate is collected and sent to the subsequent high-purity lithium salt preparation process.

[0008] Furthermore, in step (1), the cation exchange membrane is a cation exchange membrane of the type including Nafion series, Selemion CMV, FuMATech series, etc.

[0009] Furthermore, in step (1), the electrolyte in the anode chamber is a solution containing an electrolyte, wherein the electrolyte is any one of ammonium sulfate, ammonium nitrate or ammonium chloride, and the concentration of the electrolyte is 0.5-20 g / L.

[0010] Furthermore, in step (1), the alkaline solution in the cathode chamber is a sodium hydroxide solution or a sodium carbonate solution, wherein the concentration is 5-40% (wt.%).

[0011] Furthermore, in step (1), the volume of the cathode chamber solution is the same as the volume of the anode chamber electrolyte.

[0012] Furthermore, in step (4), the acid solution is any one of a hydrochloric acid solution, a sulfuric acid solution or a nitric acid solution.

[0013] The technical solution of the present invention has the following advantages over the existing waste lithium ion recycling method: 1. The lithium recovery rate of the preferred lithium extraction technology of the present invention reaches more than 99%, which has a higher lithium yield than the existing carbon thermal reduction lithium extraction technology.

[0014] 2. The combination of electrodialysis and metal complexation improves the leaching rate of lithium and reduces the leaching rate of other metals and the permeability of the membrane, thereby ensuring that the leached lithium ions can be separated from a small amount of other metal ions (such as manganese, nickel, cobalt, and iron) in the electrolyte, which is beneficial to the subsequent preparation of high-purity lithium salts.

[0015] 3. By adopting the method of the present invention, aluminum is recovered in the form of metal foil, and the aluminum is recovered while lithium is purified.

[0016] 4. In the method of the present invention, the complexing agent can be recycled, and the cost is lower than that of the existing lithium extraction technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a flow chart of the extraction method of the present invention; Figure 2 It is a schematic structural diagram of the electrodialysis cell of the present invention; In the figure, 1. electrodialysis cell 2. cathode plate 3. cathode chamber 4. anode plate 5. anode chamber 6. agitator 7. electrolyte and ethylenediaminetetraacetic acid 8. cation exchange membrane 9. water or alkaline solution. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is described clearly and completely below in conjunction with the embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Example 1

[0019] A method for purifying lithium from waste lithium-ion batteries, referring to Figure 1 , including the following steps: (1) After disassembling the waste lithium iron phosphate battery, the positive electrode sheets therein are collected, and the waste positive electrode sheets are used as the anode plate 4, and the stainless steel plate is used as the cathode plate 2. The two electrode plates are respectively connected to the positive and negative electrodes of the power supply through wires and then placed in the anode chamber 5 and cathode chamber 3 of the electrodialysis cell 1; A Nafion 117 membrane 8 is placed between the anode chamber 5 and the cathode chamber 3, a stirrer 6 is installed in the anode chamber 5, and an electrolyte and ethylenediaminetetraacetic acid 7 are injected. An ammonium sulfate solution with a concentration of 5 g / L is injected as the electrolyte, and then ethylenediaminetetraacetic acid is added. The amount of ethylenediaminetetraacetic acid added is 1.5 g / 100 ml of the electrolyte; Inject 25% NaOH solution 9 in the cathode chamber 3 in the same volume as that in the anode chamber 5, such as Figure 2 As shown; (2) Start the power supply and perform electrolysis at a voltage of 25V for 2h; Then start the stirrer, continue electrolysis for 1 h at a voltage of 25 V and a stirring speed of 100 r / min, and turn off the power supply and stirrer; The liquid in the cathode chamber is drawn out and sent to the subsequent high-purity lithium salt preparation process; (3) The slurry in the anode chamber is led out to the filtration device, the filter residue is collected, and sent to the subsequent recovery process of other metals; Collect the filtrate and proceed to step (4); (4) The filtrate obtained in step (3) was introduced into a stirred kettle containing 3 mol / L sulfuric acid solution, and the mixture was stirred at 60°C and 300 r / min for 1 h. The obtained slurry was filtered, and the residue was collected and returned to step (1) for repeated use. The filtrate is collected, and ammonia water is added to adjust the pH of the filtrate to neutral, and then it is sent to step (1) for repeated use as an electrolyte.

[0020] The concentration of all metal ions in the cathode chamber was measured and calculated that the purity of lithium in the solution reached 99.96% and the iron ion concentration was less than 3ppm; the recovery rate of lithium in the recovery process was 99.91%. Example 2

[0021] A method for purifying lithium from waste lithium-ion batteries, referring to Figure 1 , including the following steps: (1) After disassembling the waste lithium cobalt oxide battery, the positive electrode sheets therein are collected, and the waste positive electrode sheets are used as the anode plate 4, and the stainless steel plate is used as the cathode plate 2. The two electrode plates are respectively connected to the positive and negative electrodes of the power supply through wires and then placed in the anode chamber 5 and cathode chamber 3 of the electrodialysis cell; A Nafion115 membrane 8 is installed between the anode chamber 5 and the cathode chamber 3, a stirrer 6 is installed in the anode chamber 5, and an electrolyte and ethylenediaminetetraacetic acid 7 are injected. An ammonium sulfate solution with a concentration of 1 g / L is injected as the electrolyte, and then ethylenediaminetetraacetic acid is added. The amount of ethylenediaminetetraacetic acid added is 0.5 g / 100 ml of the electrolyte; Inject an aqueous solution 9 of the same volume as that of the anode chamber 5 into the cathode chamber 3, such as Figure 2 As shown; (2) Start the power supply and perform electrolysis at a voltage of 15V for 3 hours; Then start the stirrer, continue electrolysis for 4 h at a voltage of 15 V and a stirring speed of 200 r / min, and turn off the power supply and stirrer; The liquid in the cathode chamber is drawn out and sent to the subsequent high-purity lithium salt preparation process; (3) The slurry in the anode chamber is led out to the filtration device, the filter residue is collected, and sent to the subsequent recovery process of other metals; Collect the filtrate and proceed to step (4); (4) The filtrate obtained in step (3) was introduced into a stirred kettle containing 4 mol / L sulfuric acid solution, and stirred for reaction at a temperature of 30°C and a rotation speed of 200 r / min for 2 h. The obtained slurry was filtered, and the filter residue was collected and returned to step (1) for repeated use; The filtrate is collected, and ammonia water is added to adjust the filtrate to neutrality, and then sent to step (1) for repeated use as an electrolyte.

[0022] The concentration of all metal ions in the cathode chamber was measured and calculated that the purity of lithium in the solution reached 99.84% and the cobalt ion concentration was less than 5ppm; the recovery rate of lithium in the recovery process was 99.3%. Example 3

[0023] A method for purifying lithium from waste lithium-ion batteries, referring to Figure 1 , including the following steps: (1) After disassembling the waste nickel cobalt manganese oxide (NCM111) batteries, the positive electrode sheets therein are collected, and the waste positive electrode sheets are used as anode plates 4, and graphite plates are used as cathode plates 2. The two electrode plates are respectively connected to the positive and negative electrodes of a power source through wires and then placed in the anode chamber 5 and cathode chamber 3 of an electrodialysis cell 1; A Fumaep E-620 (K) membrane 8 is placed between the anode chamber 3 and the cathode chamber 5, a stirrer 6 is installed in the anode chamber 5, an electrolyte and ethylenediaminetetraacetic acid 7 are injected, an ammonium chloride solution with a concentration of 1 g / L is injected as the electrolyte, and ethylenediaminetetraacetic acid is added, and the amount of ethylenediaminetetraacetic acid added is 1.1 g / 100 ml of the electrolyte; Inject 15% Na2CO3 solution 9 of the same volume as that of the anode chamber 5 into the cathode chamber 3. Figure 2 As shown; (2) Start the power supply and perform electrolysis at a voltage of 30 V for 1 hour; Then start the stirrer, continue electrolysis for 2 h at a voltage of 30 V and a stirring speed of 300 r / min, and turn off the power supply and stirrer; The liquid in the cathode chamber is drawn out and sent to the subsequent high-purity lithium salt preparation process; (3) The slurry in the anode chamber is led out to the filtration device, the filter residue is collected, and sent to the subsequent recovery process of other metals; Collect the filtrate and proceed to step (4); (4) The filtrate obtained in step (3) was introduced into a stirred tank containing 1 mol / L hydrochloric acid solution, and the mixture was stirred at a temperature of 40°C and a rotation speed of 450 r / min for 0.5 h. The obtained slurry was filtered, and the residue was collected and returned to step (1) for repeated use; The filtrate is collected, and ammonia water is added to adjust the pH of the filtrate to neutral, and then it is sent to step (1) for repeated use as an electrolyte.

[0024] The concentration of all metal ions in the cathode chamber was measured, and it was calculated that the purity of lithium in the solution reached 99.94%, and the total concentration of nickel, cobalt and manganese ions was less than 9 ppm; the recovery rate of lithium in the recovery process was 99.1%. Example 4

[0025] A method for purifying lithium from waste lithium-ion batteries, referring to Figure 1 , including the following steps: (1) After disassembling the waste manganese phosphate lithium battery, the positive electrode sheet is collected, and the waste positive electrode sheet is used as the anode plate 4, and the titanium plate is used as the cathode plate 3. The two electrode plates are respectively connected to the positive and negative electrodes of the power supply through wires and then placed in the anode chamber 5 and cathode chamber 3 of the electrodialysis cell 1; A Selemion CMV membrane 8 is installed between the anode chamber 5 and the cathode chamber 3, a stirrer 6 is installed in the anode chamber 5, and an electrolyte and ethylenediaminetetraacetic acid 7 are injected. An ammonium nitrate solution with a concentration of 7 g / L is injected as the electrolyte, and ethylenediaminetetraacetic acid is added. The amount of ethylenediaminetetraacetic acid added is 0.8 g / 100 ml of the electrolyte; Inject 30% Na2CO3 solution 9 of the same volume as that of the anode chamber 5 into the cathode chamber 3, such as Figure 2 As shown; (2) Start the power supply and perform electrolysis at a voltage of 10 V for 6 hours; Then start the stirrer, continue electrolysis for 5 h at a voltage of 10 V and a stirring speed of 400 r / min, and turn off the power supply and stirrer; The liquid in the cathode chamber is drawn out and sent to the subsequent high-purity lithium salt preparation process; (3) The slurry in the anode chamber is led out to the filtration device, the filter residue is collected, and sent to the subsequent recovery process of other metals; Collect the filtrate and proceed to step (4); (4) The filtrate obtained in step (3) was introduced into a stirred tank containing 2.5 mol / L nitric acid solution, and stirred at a temperature of 25°C and a rotation speed of 500 r / min for 3 h. The obtained slurry was filtered, and the filter residue was collected and returned to step (1) for repeated use; The filtrate is collected, and ammonia water is added to adjust the pH of the filtrate to neutral, and then it is sent to step (1) for repeated use as an electrolyte.

[0026] The concentration of all metal ions in the cathode chamber was measured and calculated that the purity of lithium in the solution reached 99.91%, and the total concentration of iron and manganese ions was less than 10 ppm; the recovery rate of lithium in the recovery process was 99.03%.

[0027] In Examples 1-4, electrodialysis is combined with metal complexation to extract lithium from waste lithium-ion batteries using a cation exchange membrane. The purity of lithium in the resulting lithium-containing solution reaches more than 99.8%, which can be used to prepare high-purity lithium salts such as battery-grade lithium carbonate. At the same time, aluminum is recovered in the form of metal foil, and other metals in the battery material enter the electrolytic slag, thereby achieving complete separation and recovery of lithium and other metals in the electrolyte.

[0028] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for purifying lithium from waste lithium-ion batteries, characterized in that: The following steps are involved: (1) After disassembling the waste lithium-ion batteries, collect the positive electrode sheets therein, use the waste positive electrode sheets as anode plates, and use stainless steel plates, titanium plates or graphite plates as cathode plates. The two plates are connected to the positive and negative electrodes of a power source through wires and then placed in the anode chamber and cathode chamber of an electrodialysis cell; A cation exchange membrane is installed between the anode chamber and the cathode chamber, and water or alkaline solution is injected into the cathode chamber; Install a stirrer in the anode chamber, inject electrolyte, and then add ethylenediaminetetraacetic acid; (2) Start the power supply and perform the first electrolysis at a certain voltage; Then, the stirrer is started, and the second electrolysis is performed at a certain voltage and a certain stirring speed until all lithium is leached from the positive electrode sheet into the electrolyte, and the power supply and the stirrer are turned off; The liquid in the cathode chamber is drawn out and sent to the subsequent high-purity lithium salt preparation process; (3) The slurry in the anode chamber is led out to the filtration device, the filter residue is collected, and sent to the subsequent recovery process of other metals; Collect the filtrate and proceed to step (4); (4) introducing the filtrate obtained in step (3) into a stirred kettle containing an acid solution, stirring and reacting at a certain temperature and a certain speed, filtering the obtained slurry after the reaction, collecting the filter residue, and returning the obtained ethylenediaminetetraacetic acid to step (1) for repeated use; The filtrate is collected and sent to step (1) for reuse as electrolyte.

2. The method for purifying lithium in waste lithium-ion batteries according to claim 1, characterized in that: In step (1), the cation exchange membrane is a Nafion series, Selemion CMV or FuMATech type cation exchange membrane.

3. The method for purifying lithium in waste lithium-ion batteries according to claim 1, characterized in that: In step (1), the electrolyte in the anode chamber is a solution containing an electrolyte, wherein the electrolyte is any one of ammonium sulfate, ammonium nitrate or ammonium chloride, and the concentration of the electrolyte is 0.5-20 g / L.

4. The method for purifying lithium from waste lithium-ion batteries according to claim 1, characterized in that: In step (1), the amount of EDTA added into the anode chamber is 0.01-2 g / 100 ml electrolyte.

5. The method for purifying lithium in waste lithium-ion batteries according to claim 1, characterized in that: In step (1), the alkaline solution in the cathode chamber is a sodium hydroxide solution or a sodium carbonate solution with a concentration of 5-40% (wt.%).

6. The method for purifying lithium from waste lithium-ion batteries according to claim 1, characterized in that: In step (1), the volume of the cathode chamber solution is the same as the volume of the anode chamber solution.

7. The method for purifying lithium from waste lithium-ion batteries according to claim 1, characterized in that: In step (2), the power supply voltage is 5-35V, and the first electrolysis is 0.1-5h.

8. The method for purifying lithium from waste lithium-ion batteries according to claim 1, characterized in that: In step (2), the second electrolysis is carried out for 0.1-4h at a power supply voltage of 5-35V and a stirring speed of 10-500r / min.

9. The method for purifying lithium from waste lithium-ion batteries according to claim 1, characterized in that: In step (4), the acid solution is any one of hydrochloric acid solution, sulfuric acid solution or nitric acid solution, and the concentration of the acid solution is 0.1-5 mol / L.

10. The method for purifying lithium from waste lithium-ion batteries according to claim 1, characterized in that: In step (4), the temperature of the stirred tank is 10-60°C, the rotation speed is 10-500r / min, and the stirring reaction is carried out for 0.1-5h.

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