Method for electrochemically separating lithium and other metals in waste lithium ion battery

Abstract

The invention discloses a method for electrochemically separating lithium and other metals in a waste lithium ion battery, which comprises the following steps: taking a positive plate of the waste lithium ion battery as an anode plate, taking a stainless steel plate, a copper plate or a graphite plate and the like as a cathode plate, and respectively connecting the two polar plates with the anode and cathode of a power supply through leads to form an electrolytic bath; adding electrolyte and resin into the electrolytic bath, and simultaneously loading into a stirring device; the method comprises the following steps: electrolyzing under a certain voltage, electrolyzing under a stirring condition, screening electrolyte, collecting resin from oversize products, adding acid liquor, stirring for a certain time, carrying out secondary screening, collecting resin in the oversize products, and returning to the electrolysis process. According to the method, resin adsorption and electrolysis are combined, separation of lithium and other metals in the waste batteries is achieved, the purity of lithium in the obtained lithium-containing solution reaches 99.5% or above, and the lithium-containing solution can be used for preparing high-purity lithium salt; meanwhile, aluminum is recycled in the form of metal foil, other metals in the battery material enter the electrolytic slag, and the resin can be recycled.

Description

Technical Field

[0001] The invention relates to the technical field of recycling waste lithium-ion batteries, in particular to a method for electrochemically separating lithium from other metals 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] Cation exchange resin has a strong adsorption capacity for most metal ions. For example, the application number CN103035977B "A method for separating and recovering lithium from waste lithium-ion batteries" uses ion exchange resin to adsorb, separate and recover lithium ions in the leachate of waste lithium-ion batteries. The resin can be reused after desorption. However, this method cannot solve the problem of separating lithium from metal ions such as nickel, cobalt, manganese, and iron, because cation exchange resin can adsorb metal ions such as nickel, cobalt, manganese, and iron in addition to lithium ions.

[0006] 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

[0007] In view of the defects of the existing preferential lithium extraction technology, such as low lithium recovery rate or low purity of the extracted lithium, the present invention adopts a method combining resin adsorption and electrolysis, and achieves efficient separation of lithium and other metals in waste lithium-ion batteries by regulating the electrolysis / adsorption process parameters, thereby obtaining raw materials for preparing high-purity lithium salts.

[0008] A method for electrochemically separating lithium from other metals in 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, copper plates or graphite plates as cathode plates. The two plates are connected to the positive and negative electrodes of a power source through wires to form an electrolytic cell; Add electrolyte and resin into the electrolytic tank, wherein the ratio of resin to electrolyte is 0.05-2g:100-700ml, and install a stirrer in the electrolytic tank; (2) Start the power supply and electrolyze for 0.1-7h at a voltage of 5-35V; Then start the stirrer, and continue electrolysis for 0.1-5h 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 turn off the power supply and stirrer; (3) The slurry from the electrolytic cell is led out to a screening device with an aperture of 50-200 mesh, and the material on the screen is collected; The screened material is sent to the filtering device, and the lithium-ion battery positive electrode waste with lithium removed is obtained in the filter residue, which is sent to the subsequent process to recover other metals; The filtrate is a lithium-containing solution, which is sent to the subsequent high-purity lithium salt production process; (4) The sieve material of step (3) is transferred into a hydrochloric acid solution with a concentration of 0.05-5 mol / L, and stirred at a speed of 10-500 r / min for 0.1-3 h. The slurry is transferred into another screening device with an aperture of 50-200 mesh, and the sieve material is collected. The obtained resin is returned to step (1) for recycling; The undersize liquid is sent to the subsequent recovery process to recover metals such as nickel, cobalt, manganese, and iron.

[0009] Furthermore, in step (1), the electrolyte is a solution containing an electrolyte, the electrolyte is ammonium carbonate or ammonium sulfate, and the concentration of the electrolyte is 0.5-20 g / L.

[0010] Furthermore, in step (1), the resin is a strong acid cation exchange resin or a weak acid cation exchange resin.

[0011] Compared with the existing waste lithium ion recycling method, the technical solution of the present invention has the following advantages: 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 combination of resin adsorption and electrolysis, combined with the regulation of electrolysis parameters and resin adsorption conditions, improves the leaching rate of lithium. A small amount of leached nickel, cobalt, manganese, iron and other metals are adsorbed by the resin, ensuring that the leached lithium ions can be efficiently separated from a small amount of other metal ions (such as manganese, nickel, cobalt, iron) in the electrolyte, which is conducive to the preparation of high-purity lithium salts using the post-electrolysis liquid.

[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 resin can be recycled after desorption, which significantly reduces the cost of the separation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a flow chart of the electrochemical separation method of the present invention; Figure 2 A schematic diagram of the structure of an electrolytic cell used in the electrochemical separation method of the present invention; In the figure, 1. electrolytic cell 2. cathode plate 3. anode plate 4. agitator 5. electrolyte and resin. 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 electrochemically separating lithium from other metals in waste lithium-ion batteries, referring to Figure 1 , including the following steps: (1) Disassemble the waste lithium iron phosphate battery and collect the positive electrode; refer to Figure 2 The waste positive electrode sheet is used as the anode plate 3, and the stainless steel plate is used as the cathode plate 2. The two plates are connected to the positive and negative electrodes of the power source through wires to form an electrolytic cell 1; Add 2g / L ammonium carbonate solution and 001*7 type cation exchange resin 5 into the electrolytic cell 1, wherein the ratio of resin to electrolyte is 0.5g:300ml, and install a stirrer 4 into the electrolytic cell 1; (2) Start the power supply and perform electrolysis at a voltage of 35 V for 2 h; Then start the stirrer, continue electrolysis for 0.5 h at a voltage of 35 V and a stirring speed of 100 r / min, and then turn off the power supply and stirrer; (3) The slurry from the electrolytic cell is led out to a screening device with an aperture of 50 mesh, and the material on the screen is collected; The screened material is sent to the filtering device, and the lithium-ion battery positive electrode waste with lithium removed is obtained in the filter residue, which is sent to the subsequent process to recover other metals; The filtrate is a lithium-containing solution, which is sent to the subsequent lithium salt production process; (4) The sieve material of step (3) is transferred into a hydrochloric acid solution with a concentration of 3 mol / L, and stirred at a speed of 200 r / min for 0.5 h. The slurry is transferred into another screening device with an aperture of 50 mesh, and the sieve material is collected. The obtained resin is returned to step (1) for recycling; The undersize liquid is sent to the subsequent recovery process to recover the iron therein.

[0018] The concentration of metal ions in the electrolyte was measured and calculated, the purity of lithium in the solution reached 99.85%, and the iron ion concentration was less than 10ppm; the recovery rate of lithium in the recovery process was 99.1%. Example 2

[0019] A method for electrochemically separating lithium from other metals in waste lithium-ion batteries, referring to Figure 1 , including the following steps: (1) Disassemble the waste lithium cobalt oxide batteries and collect the positive electrode sheets; Figure 2 The waste positive electrode sheet is used as the anode plate 3, and the stainless steel plate is used as the cathode plate 2. The two plates are connected to the positive and negative electrodes of the power source through wires to form an electrolytic cell 1; Add 7g / L ammonium carbonate solution and 001*7 type cation exchange resin 5 into the electrolytic cell 1, wherein the ratio of resin to electrolyte is 0.2g:400ml, and install a stirrer 4 into the electrolytic cell 1; (2) Start the power supply and electrolyze at a voltage of 25 V for 4 hours; Then start the stirrer, continue electrolysis for 3 h at a voltage of 25 V and a stirring speed of 400 r / min, and then turn off the power supply and stirrer; (3) Lead the slurry from the electrolytic cell to a screening device with an aperture of 100 mesh, and collect the material on the screen; The screened material is sent to the filtering device, and the lithium-ion battery positive electrode waste with lithium removed is obtained in the filter residue, which is sent to the subsequent process to recover other metals; The filtrate is a lithium-containing solution, which is sent to the subsequent lithium salt production process; (4) The sieve material of step (3) is transferred into a hydrochloric acid solution with a concentration of 1 mol / L, and stirred at a speed of 400 r / min for 5 h. The slurry is transferred into another screening device with an aperture of 100 mesh, and the sieve material is collected. The obtained resin is returned to step (1) for recycling; The undersize liquid is sent to the subsequent recovery process to recover the cobalt therein.

[0020] The concentration of metal ions in the electrolyte was measured and calculated, the purity of lithium in the solution reached 99.7%, and the cobalt ion concentration was less than 7ppm; the recovery rate of lithium in the recovery process was 98.96%. Example 3

[0021] A method for electrochemically separating lithium from other metals in waste lithium-ion batteries, referring to Figure 1 , including the following steps: (1) Disassemble the used nickel cobalt manganese oxide (NCM111) batteries and collect the positive plates; refer to Figure 2 The waste positive electrode sheet is used as the anode plate 3, and the graphite plate is used as the cathode plate 2. The two plates are connected to the positive and negative electrodes of the power supply through wires to form an electrolytic cell 1; Add 2g / L ammonium sulfate solution and CH-90 cation exchange resin 5 into the electrolytic cell 1, wherein the ratio of resin to electrolyte is 1g:500ml, and install a stirrer 4 into the electrolytic cell 1; (2) Start the power supply and perform electrolysis at a voltage of 15V for 6 hours; Then start the stirrer, continue electrolysis for 2 h at a voltage of 15 V and a stirring speed of 500 r / min, and then turn off the power supply and stirrer; (3) Lead the slurry from the electrolytic cell to a screening device with an aperture of 200 meshes, and collect the material on the screen; The screened material is sent to the filtering device, and the lithium-ion battery positive electrode waste with lithium removed is obtained in the filter residue, which is sent to the subsequent process to recover other metals; The filtrate is a lithium-containing solution, which is sent to the subsequent lithium salt production process; (4) The sieve material of step (3) is transferred into a hydrochloric acid solution with a concentration of 5 mol / L, and stirred at a speed of 100 r / min for 1 h. The slurry is transferred into another screening device with an aperture of 200 mesh, and the sieve material is collected. The obtained resin is returned to step (1) for recycling; The undersize liquid is sent to the subsequent recovery process to recover the nickel, cobalt and manganese therein.

[0022] The concentration of metal ions in the electrolyte was measured and calculated that the purity of lithium in the solution reached 99.7%, and the total concentration of nickel, cobalt and manganese ions was less than 10ppm; the recovery rate of lithium in the recovery process was 99.6%. Example 4

[0023] A method for electrochemically separating lithium from other metals in waste lithium-ion batteries, referring to Figure 1 , including the following steps: (1) Disassemble the waste lithium manganese phosphate batteries and collect the positive plates; Figure 2 The waste positive electrode sheet is used as the anode plate 3, and the copper plate is used as the cathode plate 2. The two plates are connected to the positive and negative electrodes of the power supply through wires to form an electrolytic cell 1; Add 5g / L ammonium sulfate solution and CH-90 cation exchange resin 5 into the electrolytic cell 1, wherein the ratio of resin to electrolyte is 0.4g:700ml, and install a stirrer 4 into the electrolytic cell 1; (2) Start the power supply and perform electrolysis at a voltage of 20 V for 3 hours; Then start the stirrer, continue electrolysis for 1 h at a voltage of 20 V and a stirring speed of 450 r / min, and then turn off the power supply and stirrer; (3) Lead the slurry from the electrolytic cell to a screening device with an aperture of 100 mesh, and collect the material on the screen; The screened material is sent to the filtering device, and the lithium-ion battery positive electrode waste with lithium removed is obtained in the filter residue, which is sent to the subsequent process to recover other metals; The filtrate is a lithium-containing solution, which is sent to the subsequent lithium salt production process; (4) The sieve material of step (3) is transferred into a hydrochloric acid solution with a concentration of 2 mol / L, and stirred at a rotation speed of 300 r / min for 1 hour. The slurry is transferred into another screening device with an aperture of 100 mesh, and the sieve material is collected. The obtained resin is returned to step (1) for recycling; the undersize liquid is sent to a subsequent recovery process to recover the iron and manganese therein.

[0024] The concentration of metal ions in the electrolyte was measured and calculated that the purity of lithium in the solution reached 99.5%, and the total concentration of iron and manganese ions was less than 10ppm; the recovery rate of lithium in the recovery process was 99.1%.

[0025] In Examples 1-4, a method combining resin adsorption and electrolysis is adopted, and the purity of lithium in the obtained lithium-containing solution reaches more than 99.5%, which can be used to prepare high-purity lithium salts; 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 electrochemically separating lithium from other metals in 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, copper plates or graphite plates as cathode plates. The two plates are connected to the positive and negative electrodes of a power source through wires to form an electrolytic cell; Add electrolyte and resin into the electrolytic tank and install the agitator at the same time; (2) Start the power supply and perform the first electrolysis at a certain voltage; Then start the stirrer, and perform the second electrolysis at a certain voltage and stirring speed until all lithium is leached from the positive electrode into the electrolyte, and then turn off the power supply and stirrer; (3) Leading the slurry from the electrolytic cell to a screening device to collect the material on the screen; The screened material is sent to the filtering device, and the waste battery positive electrode waste with lithium removed is obtained in the filter residue, which is sent to the subsequent process to recover other metals; The filtrate is a lithium-containing solution, which is sent to the subsequent high-purity lithium salt production process; (4) transferring the sieve material of step (3) into a hydrochloric acid solution, stirring at a certain stirring speed for a period of time, transferring the slurry into another screening device, collecting the sieve material, and returning the obtained resin to step (1) for recycling; The undersize liquid is sent to the subsequent recovery process to recover other metals.

2. The method for electrochemically separating lithium from other metals in waste lithium-ion batteries according to claim 1, characterized in that: In step (1), the ratio of resin to electrolyte is 0.05-2g:100-700ml.

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

4. The method for electrochemically separating lithium from other metals in waste lithium-ion batteries according to claim 1, characterized in that: In step (1), the resin is a strong acid cation exchange resin or a weak acid cation exchange resin.

5. The method for electrochemically separating lithium from other metals in 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 time is 0.1-7h.

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

7. The method for electrochemically separating lithium from other metals in waste lithium-ion batteries according to claim 1, characterized in that: In steps (3) and (4), the aperture of the screening device is 50-200 mesh.

8. The method for electrochemically separating lithium from other metals in waste lithium-ion batteries according to claim 1, characterized in that: In step (4), the concentration of the hydrochloric acid solution is 0.05-5 mol / L, the stirring speed is 10-500 r / min, and the stirring time is 0.1-3 h.

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