Method for separating lithium and other metals in waste lithium ion battery through electrodialysis

Abstract

The invention discloses a method for separating lithium and other metals in a waste lithium ion battery through electrodialysis, which comprises the following steps of: firstly, carrying out electrodialysis treatment on a positive plate of the waste lithium ion battery, transferring lithium from the positive plate into an anode chamber solution, then replacing the positive plate of the waste lithium ion battery with other electrode plates, and continuously carrying out electrodialysis for a certain time; and transferring all lithium into the solution in the cathode chamber through the electrodialysis membrane. According to the method, lithium in the waste battery material is separated from other metals, and the separated lithium 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 separating lithium from other metals in waste lithium-ion batteries by electrodialysis. 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 has the defect of low lithium recovery rate (usually less than 90%).

[0004] Electrochemical lithium extraction is one of the methods for preferential lithium extraction, and the lithium recovery rate is relatively high (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 metal ions leached 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 for 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 metal ions leached from lithium and transfer them out of the electrolyte. At present, the technology for electrolytic lithium extraction has failed to solve the problem of separating lithium from other small amounts of metals in the electrolyte. Therefore, it is also necessary to find a method for completely separating and recovering lithium from other metals in the electrolyte. Summary of the invention

[0005] The present invention aims to solve the problem that the lithium recovery rate of the existing preferential lithium extraction technology is low or the purity of the extracted lithium is not high, and provides a method for separating lithium from other metals by electrodialysis. The method adopts two-step electrodialysis, and with the help of a cation exchange membrane, lithium can be quickly leached from the positive electrode sheet of the waste battery and completely separated from other metals in the electrolyte, thereby obtaining a raw material for preparing high-purity lithium salts.

[0006] A method for separating lithium from other metals in waste lithium-ion batteries by electrodialysis, comprising the following steps: (1) After disassembling the waste lithium-ion batteries, collect the positive electrode sheets therein, connect the waste positive electrode sheets to the positive electrode of the power source through a wire, use them as the anode plates of the electrodialysis cell, and place them in the anode chamber of the electrodialysis cell. Use plates such as stainless steel plates, titanium plates or graphite plates as the cathode plates of the electrodialysis cell, connect them to the negative electrode of the power source through a wire, and place them in the cathode chamber of the electrodialysis cell; A cation exchange membrane is installed between the anode chamber and the cathode chamber, an electrolyte is injected into the anode chamber, and water or an alkaline solution is injected into the cathode chamber; (2) starting the power supply, electrolyzing for 0.5-6h at a voltage of 5-35V, turning off the power supply after electrolysis, disconnecting the positive electrode sheet of the waste battery from the power supply wire, taking out the positive electrode sheet, and sending it to step (4) for further processing; (3) Connect the electrode such as stainless steel plate, copper plate or graphite plate to the positive lead of the power supply, place it in the anode chamber, start the power supply again, and perform electrolysis at a voltage of 5-35V for 0.5-6h; The solution in the cathode chamber is drawn out for subsequent preparation of high-purity lithium salt; (4) placing the electrolyzed positive electrode sheet taken out in step (2) in a water bath with a stirrer and stirring at a speed of 10-300 r / min for 5-30 min. At this time, all the waste in the positive electrode sheet falls off the aluminum foil, and the aluminum foil is collected; The slurry containing the waste is filtered to obtain the lithium-ion battery positive electrode waste from which lithium has been removed in the filter residue; (5) The slurry in the anode chamber obtained in step (3) is led out to another filtering device, the filter residue is collected and mixed with the positive electrode waste obtained in step (4), and then sent to the subsequent recovery process of other metals; The filtrate is collected and returned to step (1) for recycling as electrolyte.

[0007] 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 carbonate, ammonium nitrate, or ammonium chloride, and the concentration of the electrolyte is 0.5-20 g / L.

[0008] Furthermore, in step (1), the alkaline solution in the cathode chamber is a sodium hydroxide solution or a sodium carbonate solution, and the concentration of the alkaline solution is 5-40% (wt.%).

[0009] Furthermore, in step (1), the volume of the cathode chamber solution is the same as the volume of the anode chamber electrolyte.

[0010] Furthermore, the cation exchange membrane in step (1) is a cation exchange membrane of the Nafion series, Selemion CMV, FuMATech series, etc.

[0011] 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.

[0012] 2. The two-step electrodialysis operation is combined with the regulation of electrolysis parameters to improve the lithium leaching rate, effectively inhibit the leaching of other metals in the positive electrode waste of waste batteries, and reduce the leaching rate and membrane permeability of other metals, thereby ensuring that the leached lithium ions can not only be separated from a small amount of other metal ions (such as manganese, nickel, cobalt, and iron) in the electrolyte, but also can be completely removed from the electrolyte, which is beneficial to the subsequent preparation of high-purity lithium salts.

[0013] 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.

[0014] 4. The method of the present invention has the advantages of short process flow and simple operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 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 electrolyte 7. cation exchange membrane 8. water or alkaline solution. DETAILED DESCRIPTION

[0016] 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

[0017] A method for separating lithium from other metals in waste lithium-ion batteries by electrodialysis, referring to Figure 1 , including the following steps: (1) After disassembling the waste lithium iron phosphate battery, collect the positive electrode sheets therein, connect the waste positive electrode sheets to the positive electrode of the power source through a wire and use them as the anode plate 4 of the electrodialysis cell 1, and place them in the anode chamber 5 of the electrodialysis cell 1; use a stainless steel plate as the cathode plate 2 of the electrodialysis cell 1, connect it to the negative electrode of the power source through a wire and place it in the cathode chamber 3 of the electrodialysis cell 1; A Nafion 115 membrane 7 is placed between the anode chamber 5 and the cathode chamber 3, a 10 g / L ammonium sulfate solution is injected into the anode chamber 5 as an electrolyte 6, and water 8 of the same volume as that of the anode chamber 5 is injected into the cathode chamber 3. Figure 1 As shown; (2) Start the power supply, perform electrolysis at a voltage of 30V for 4 hours, and then turn off the power supply after electrolysis. Disconnect the positive electrode sheet of the waste battery from the power supply wire, take out the positive electrode sheet, and send it to step (4) for further processing; (3) Connect the stainless steel plate to the positive wire of the power supply, place it in the anode chamber, start the power supply again, and perform electrolysis at a voltage of 30 V for 1 hour; The solution in the cathode chamber is drawn out for subsequent preparation of high-purity lithium salt; (4) placing the electrolyzed positive electrode sheet taken out in step (2) in a water bath with a stirrer and stirring at a speed of 50 r / min for 15 min. At this time, all the waste materials in the waste positive electrode sheet fall off from the aluminum foil, and the aluminum foil is collected; The slurry containing the waste is filtered to obtain the lithium-ion battery positive electrode waste from which lithium has been removed in the filter residue; (5) The slurry in the anode chamber obtained in step (3) is led out to another filtering device, the filter residue is collected and mixed with the positive electrode waste obtained in step (4), and then sent to the subsequent recovery process of other metals; The filtrate is collected and returned to step (1) for recycling as electrolyte.

[0018] The concentration of all metal ions in the cathode chamber was measured and calculated that the purity of lithium in the solution reached 99.5% and the iron ion concentration was less than 10ppm; the recovery rate of lithium in the recovery process was 99.3%. Example 2

[0019] A method for separating lithium from other metals in waste lithium-ion batteries by electrodialysis, 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 connected to the positive electrode of the power source through a wire and used as the anode plate 4 of the electrodialysis cell 1, and placed in the anode chamber 5 of the electrodialysis cell 1. A stainless steel plate is used as the cathode plate 2 of the electrodialysis cell 1, and is connected to the negative electrode of the power source through a wire and placed in the cathode chamber 3 of the electrodialysis cell 1; A Fumaep E-620 (K) membrane 7 is installed between the anode chamber 5 and the cathode chamber 3. An ammonium chloride solution with a concentration of 1 g / L is injected into the anode chamber 5 as an electrolyte 6. A 30% NaOH solution 8 with the same volume as that of the anode chamber 5 is injected into the cathode chamber 3. Figure 1 As shown; (2) starting the power supply, electrolyzing for 2 h at a voltage of 15 V, turning off the power supply after electrolysis, disconnecting the positive electrode sheet of the waste battery from the wire of the power supply, taking out the positive electrode sheet, and sending it to step (4) for further processing; (3) Connect the graphite plate to the positive wire of the power supply, place it in the anode chamber, start the power supply again, and perform electrolysis at a voltage of 15 V for 5 hours; The solution in the cathode chamber is drawn out for subsequent preparation of high-purity lithium salt; (4) placing the electrolyzed positive electrode sheet taken out in step (2) in a water bath with a stirrer and stirring at a speed of 150 r / min for 20 min. At this time, all the waste materials in the waste positive electrode sheet fall off from the aluminum foil, and the aluminum foil is collected; The slurry containing the waste is filtered to obtain the lithium-ion battery positive electrode waste from which lithium has been removed in the filter residue; (5) The slurry in the anode chamber obtained in step (3) is led out to another filtering device, the filter residue is collected and mixed with the positive electrode waste obtained in step (4), and then sent to the subsequent recovery process of other metals; The filtrate is collected and returned to step (1) for recycling as 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 99.83% and the cobalt ion concentration was less than 5ppm; the recovery rate of lithium in the recovery process was 99.1%. Example 3

[0021] A method for separating lithium from other metals in waste lithium-ion batteries by electrodialysis, 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 connected to the positive electrode of the power source through a wire and used as the anode plate 4 of the electrodialysis cell 1, and placed in the anode chamber 5 of the electrodialysis cell 1. A graphite plate is used as the cathode plate 2 of the electrodialysis cell 1, and is connected to the negative electrode of the power source through a wire and placed in the cathode chamber 3 of the electrodialysis cell 1; A Nafion 117 membrane 6 is placed between the anode chamber 5 and the cathode chamber 3. A 5 g / L ammonium nitrate solution is injected into the anode chamber 5 as an electrolyte 6. A 15% Na2CO3 solution 8 having the same volume as that of the anode chamber 5 is injected into the cathode chamber 3. Figure 1 As shown; (2) starting the power supply, electrolyzing for 5 hours at a voltage of 30 V, turning off the power supply after electrolysis, disconnecting the positive electrode sheet of the waste battery from the wire of the power supply, taking out the positive electrode sheet, and sending it to step (4) for further processing; (3) Connect the titanium sheet to the positive wire of the power supply, place it in the anode chamber, start the power supply again, and perform electrolysis at a voltage of 30 V for 3 hours; The solution in the cathode chamber is drawn out for subsequent preparation of high-purity lithium salt; (4) placing the electrolyzed positive electrode sheet taken out in step (2) in a water bath with a stirrer and stirring at a speed of 300 r / min for 5 min. At this time, all the waste materials in the waste positive electrode sheet fall off from the aluminum foil, and the aluminum foil is collected; The slurry containing the waste is filtered to obtain the lithium-ion battery positive electrode waste from which lithium has been removed in the filter residue; (5) The slurry in the anode chamber obtained in step (3) is led out to another filtering device, the filter residue is collected and mixed with the positive electrode waste obtained in step (4), and then sent to the subsequent recovery process of other metals; The filtrate is collected and returned to step (1) for recycling as 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 99.75%, and the total concentration of nickel, cobalt and manganese ions was less than 10ppm; the recovery rate of lithium in the recovery process was 99.3%. Example 4

[0023] A method for separating lithium from other metals in waste lithium-ion batteries by electrodialysis, referring to Figure 1 , including the following steps: (1) After disassembling the waste manganese phosphate lithium battery, collect the positive electrode sheet therein, connect the waste positive electrode sheet to the positive electrode of the power source through a wire and use it as the anode plate 4 of the electrodialysis cell 1, and place it in the anode chamber 5 of the electrodialysis cell 1; use a titanium plate as the cathode plate 2 of the electrodialysis cell 1, connect it to the negative electrode of the power source through a wire and place it in the cathode chamber 3 of the electrodialysis cell 1; A Selemion CMV membrane 6 is installed between the anode chamber 5 and the cathode chamber 3, a 3 g / L ammonium carbonate solution is injected into the anode chamber 5 as an electrolyte 6, and a 5% NaOH solution 8 having the same volume as that of the anode chamber 5 is injected into the cathode chamber 3. Figure 1 As shown; (2) starting the power supply, and conducting electrolysis for 0.5 h at a voltage of 10 V. After electrolysis, turning off the power supply, disconnecting the positive electrode sheet of the waste battery from the wire of the power supply, taking out the positive electrode sheet, and sending it to step (4) for further processing; (3) Connect the graphite plate to the positive lead of the power supply, place it in the anode chamber, start the power supply again, and perform electrolysis at a voltage of 10 V for 6 hours; The solution in the cathode chamber is drawn out for subsequent preparation of high-purity lithium salt; (4) placing the electrolyzed positive electrode sheet taken out in step (2) in a water bath with a stirrer and stirring at a speed of 30 / min for 25 min. At this time, all the waste materials in the waste positive electrode sheet fall off from the aluminum foil, and the aluminum foil is collected; The slurry containing the waste is filtered to obtain the lithium-ion battery positive electrode waste from which lithium has been removed in the filter residue; (5) The slurry in the anode chamber obtained in step (3) is led out to another filtering device, the filter residue is collected and mixed with the positive electrode waste obtained in step (4), and then sent to the subsequent recovery process of other metals; The filtrate is collected and returned to step (1) for recycling as electrolyte.

[0024] The concentration of all metal ions in the cathode chamber was measured and calculated that the purity of lithium in the solution reached 99.67%, and the total concentration of manganese and iron ions was less than 5ppm; the recovery rate of lithium in the recovery process was 99.3%.

[0025] In Example 1-4, two-step electrodialysis is adopted, with the help of cation exchange membrane, the purity of lithium in the obtained lithium-containing solution reaches more than 99.5%, which can be used to prepare high-purity lithium salt; at the same time, aluminum is recovered in the form of metal foil, and other metals in the battery material enter the electrolytic slag, realizing the complete separation and recovery of lithium and other metals in the electrolyte.

[0026] 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 separating lithium from other metals in waste lithium-ion batteries by electrodialysis, characterized in that: The following steps are involved: (1) After disassembling the waste lithium-ion batteries, collect the positive electrode sheets therein, connect the waste positive electrode sheets to the positive electrode of the power source through a wire, and use them as the anode plates of the electrodialysis cell, and place them in the anode chamber of the electrodialysis cell. Use a stainless steel plate, a titanium plate, or a graphite plate as the cathode plate of the electrodialysis cell, connect it to the negative electrode of the power source through a wire, and place it in the cathode chamber of the electrodialysis cell; A cation exchange membrane is installed between the anode chamber and the cathode chamber, an electrolyte is injected into the anode chamber, and water or an alkaline solution is injected into the cathode chamber; (2) starting the power supply, performing electrolysis at a certain voltage, and then turning off the power supply after electrolysis, disconnecting the positive electrode sheet of the waste battery from the wire of the power supply, taking out the positive electrode sheet, and sending it to step (4) for further processing; (3) Connect the stainless steel plate, titanium plate or graphite plate to the positive lead of the power supply, place it in the anode chamber, start the power supply again, and perform electrolysis at a certain voltage; The solution in the cathode chamber is drawn out for subsequent preparation of high-purity lithium salt; (4) placing the electrolyzed positive electrode sheet taken out in step (2) in a water bath with a stirrer and stirring at a certain speed until all the waste in the positive electrode sheet falls off the aluminum foil, and collecting the aluminum foil; The slurry containing the waste is filtered to obtain the lithium-ion battery positive electrode waste from which lithium has been removed in the filter residue; (5) The slurry in the anode chamber obtained in step (3) is led out to another filtering device, the filter residue is collected and mixed with the positive electrode waste obtained in step (4), and then sent to the subsequent recovery process of other metals; The filtrate is collected and returned to step (1) for recycling as electrolyte.

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

3. The method for separating lithium from other metals in waste lithium-ion batteries by electrodialysis 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, and the concentration of the alkaline solution is 5-40% (wt.%).

4. The method for separating lithium from other metals in waste lithium-ion batteries by electrodialysis 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 electrolyte.

5. The method for electrodialysis separation of lithium and other metals 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.

6. The method for separating lithium from other metals in waste lithium-ion batteries by electrodialysis according to claim 1, characterized in that: In step (2) and step (3), the voltage is 5-35V and the electrolysis time is 0.5-6h.

7. The method for separating lithium from other metals in waste lithium-ion batteries by electrodialysis according to claim 1, characterized in that: In step (4), the speed of the stirrer is 10-300 r / min, and the stirring time is 5-30 min.

Images