A method for the integrated whole-chain recovery of lithium from batteries and storage of carbon dioxide

Abstract

This text discloses a method for the integrated whole-chain recovery of lithium from batteries and storage of carbon dioxide, which includes the following steps: Electrochemical lithium extraction is carried out using an electrolytic cell. A gas containing carbon dioxide and hydrogen fluoride is introduced into the solution in the cathode chamber of the electrolytic cell, lithium fluoride precipitate is obtained in the anode chamber, and carbonate wastewater is obtained in the cathode chamber. The electrolytic cell includes an anode rich in lithium battery materials, a cathode poor in lithium battery materials, a monovalent anion exchange membrane, a cathode chamber solution, and an anode chamber solution. The cathode chamber and the anode chamber are separated by a monovalent anion exchange membrane.

Description

Technical Field

[0001] This application belongs to the field of lithium recycling, and specifically relates to a method for the integrated whole-chain of battery lithium recycling and carbon dioxide storage. Background Art

[0002] In recent years, with the rapid development of new energy vehicles, the production and consumption of lithium-ion batteries have been increasing continuously. The number of waste lithium-ion batteries is about to reach a peak. If waste lithium batteries are discarded randomly, it will not only cause serious environmental pollution but also result in waste of resources. Therefore, the recycling of waste batteries has become the focus of people's attention. At present, the commonly used pretreatment processes for battery recycling are pyrolysis and dry crushing. Pyrolysis is often used for battery waste with electrolyte and has a wider application range. However, the pyrolysis temperature is relatively high, and a large amount of carbon emissions will be generated during the production process, which is a process that requires key attention in carbon emission control in the integrated whole-chain industrial chain.

[0003] At present, the treatment of battery recycling tail gas mostly adopts post-combustion caustic washing. Chinese Patent Document CN114100318A discloses a method for reducing and detoxifying waste gas in the process of recycling waste lithium batteries. Through high-temperature pyrolysis in a closed and nitrogen atmosphere, followed by incineration of organic waste gas, and then dust removal and caustic washing, the waste gas can meet the emission standards. Chinese Patent Document CN110508057A first removes the dust-containing particulate matter in the waste gas generated during the lithium battery recycling process through a dust removal device, then removes most of the fluorine-containing components in the waste gas through a two-stage circulating absorption tower of alkali solution, and then removes the volatile organic compounds therein through combustion. However, in this process, the fluoride ions contained in the tail gas are usually converted into calcium fluoride that is difficult to utilize, and carbon dioxide is directly emitted, which is not conducive to carbon emission reduction in the industrial chain and the resource utilization of waste gas.

[0004] How to effectively extract lithium while reasonably reducing carbon emissions or even resource-utilizing carbon emissions during the recycling process of waste lithium batteries is one of the current research focuses. Summary of the Invention

[0005] In view of the above problems in related technologies regarding how to effectively extract lithium while reasonably reducing carbon emissions or even resource-utilizing carbon emissions during the recycling process of waste lithium batteries, this application will provide a method for the integrated whole-chain of battery lithium recycling and carbon dioxide storage.

[0006] To achieve the above object, the specific technical solutions include the following:

[0007] A method for recycling lithium from batteries, comprising the following steps:

[0008] Use a lithium-rich battery material as the anode, a lithium-poor battery material as the cathode, and isolate them with a monovalent anion exchange membrane between the anode and the cathode to form an anode chamber and a cathode chamber. Add an anode chamber solution and a cathode chamber solution to the anode chamber and the cathode chamber respectively to form an electrolytic cell;

[0009] Use the electrolytic cell to carry out an electrochemical reaction to extract lithium, and then introduce a gas containing carbon dioxide and hydrogen fluoride into the cathode chamber solution of the electrolytic cell. Lithium fluoride precipitate is obtained in the anode chamber, and carbonate wastewater is obtained in the cathode chamber.

[0010] Electrochemical lithium extraction refers to a method of extracting lithium from compounds by using an electrochemical reaction. Its principle is to extract lithium ions from compounds by using the current in the electrolytic cell. In the present invention, electrochemical lithium extraction is carried out by using a specific electrolytic cell. Lithium ions are enriched in the anode chamber, and an alkaline solution or alkaline brine is formed in the cathode chamber. Then, a gas containing carbon dioxide and HF is introduced into the cathode chamber solution. The alkaline cathode chamber solution effectively absorbs carbon dioxide and HF. Under the influence of the anion membrane and electrode adsorption, by using a monovalent anion exchange membrane, fluoride ions are attracted into the anode chamber to combine with lithium ions to form lithium fluoride precipitate. At the same time, the monovalent anion exchange membrane can prevent carbonate from migrating to the anode chamber, thus ensuring that lithium carbonate precipitate is not mixed into the lithium fluoride precipitate; the remaining solution in the cathode chamber is a high-concentration carbonate wastewater solution. The high-concentration carbonate solution can be resourcefully utilized in the impurity removal of salt lake brine. The carbon dioxide therein is converted into carbonate to form stable carbonates with Ca 2+ 、Mg 2+ and other ions, achieving the effect of fixing carbon dioxide, reducing carbon emissions, and at the same time being able to reduce the calcium and magnesium content in the salt lake, realizing preliminary impurity removal; and the fluoride ion concentration in this wastewater solution is low and can meet the discharge standard.

[0011] In one embodiment, in the gas containing carbon dioxide and hydrogen fluoride, the volume ratio of carbon dioxide to hydrogen fluoride is (50 - 1):(1 - 5); the flow rate of the gas containing carbon dioxide and hydrogen fluoride is 1 - 500 mL / min.

[0012] In another embodiment, in the gas containing carbon dioxide and hydrogen fluoride, the volume ratio of carbon dioxide to hydrogen fluoride is (10 - 5):1; the flow rate of the gas containing carbon dioxide and hydrogen fluoride is 20 - 100 mL / min.

[0013] Under the above parameters, the fluoride ion concentration in this wastewater solution is low and can meet the discharge standard.

[0014] In one embodiment, the concentration of cations in the cathode chamber solution is 0.2 - 2 mol / L.

[0015] In one embodiment, the concentration of cations in the anode chamber solution is 0.2 - 2 mol / L.

[0016] In one embodiment, the anode chamber solution includes at least one of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate.

[0017] In one embodiment, the lithium-rich battery material includes at least one of a lithium-rich ion sieve and a lithium-ion battery cathode material; the lithium-poor battery material includes at least one of a lithium-poor ion sieve and an inert electrode; the cathode chamber solution includes at least one of sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, and alkaline brine. The lithium-rich ion sieve and the lithium-ion battery cathode material can both be selected from waste lithium-rich ion sieves and lithium-ion battery cathode materials, facilitating the resource utilization of battery waste materials.

[0018] In one embodiment, the lithium-rich ion sieve includes lithium-rich lithium iron phosphate; the lithium-poor ion sieve includes lithium-poor lithium iron phosphate.

[0019] In one embodiment, the lithium-ion battery cathode material includes a lithium cobalt oxide battery cathode material; the inert electrode includes at least one of a calomel electrode and a carbon electrode.

[0020] In one embodiment, the pH value of the alkaline brine is 9 - 11.

[0021] In one embodiment, when the lithium-rich battery material is a lithium-rich ion sieve, the lithium-poor battery material is a lithium-poor ion sieve, and the cathode chamber solution is alkaline brine, a constant voltage is applied to the electrolytic cell, and the constant voltage is 0.1V - 0.9V. When the current of the electrolytic cell ≤ 0.2 mA, the electrochemical lithium extraction ends.

[0022] In one embodiment, when the lithium-rich battery material is a lithium-rich ion sieve, the lithium-poor battery material is a lithium-poor ion sieve, and the cathode chamber solution is alkaline brine, a constant current is applied to the electrolytic cell, the constant current is 1 mA - 10 mA, the time for electrochemical lithium extraction is 6 - 12 h, and the electrochemical lithium extraction ends after repeating the electrochemical lithium extraction 3 - 5 times.

[0023] In one embodiment, when the lithium-poor battery material is a lithium-ion battery cathode material, the lithium-poor battery material is an inert electrode, and the cathode chamber solution includes at least one of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate, a constant current or a constant voltage is applied to the electrolytic cell.

[0024] In one embodiment, the constant current is 0.1C - 2C, and the time for electrochemical lithium extraction is 3 - 10 h.

[0025] In one embodiment, the constant voltage is 1.5V - 2.5V; the time for electrochemical lithium extraction is 3 - 10 h.

[0026] In one embodiment, when the pH value of the cathode chamber solution ≤ 7, the gas containing carbon dioxide and hydrogen fluoride is stopped from being introduced.

[0027] The present application has the following beneficial effects: By using electrochemical lithium extraction, lithium ions are enriched in the anode chamber, an alkaline solution or alkaline brine is formed in the cathode chamber, and a gas containing carbon dioxide and HF is introduced into the cathode chamber solution. The alkaline cathode chamber solution effectively absorbs carbon dioxide and HF. Under the influence of the anion exchange membrane and electrode adsorption, using a monovalent anion exchange membrane, fluoride ions are attracted into the anode chamber to combine with lithium ions to form lithium fluoride precipitate. At the same time, the monovalent anion exchange membrane can prevent carbonate ions from migrating to the anode chamber, thus ensuring that no lithium carbonate precipitate is mixed into the lithium fluoride precipitate; the remaining solution in the cathode chamber is a high-concentration carbonate wastewater solution, and the high-concentration carbonate solution can be resourcefully utilized in the removal of impurities from salt lake brine. The carbon dioxide therein is converted into carbonate ions to form stable carbonates with Ca 2+ 、Mg 2+ and other ions, achieving the effect of fixing carbon dioxide, reducing carbon emissions, and at the same time being able to reduce the calcium and magnesium content in the salt lake, realizing preliminary impurity removal. The method of the present invention obtains relatively pure lithium fluoride through the lithium extraction from salt lake in the electrolytic cell, absorbs carbon dioxide gas and converts it into carbonate ions for storage, and the converted carbonate ions and lithium fluoride can be further utilized, realizing an integrated process of lithium extraction from salt lake, absorption, and conversion of carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the process flow diagram of an embodiment of the present invention.

[0029] Figure 2 It is the process flow diagram of another embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] To better illustrate the purpose, technical solutions, and advantages of this article, the technical solutions will be further described through specific embodiments below.

[0031] Example 1

[0032] S1: Using the waste lithium-ion battery cathode material as the anode and an inert electrode as the cathode (calomel electrode), the cathode chamber and the anode chamber are separated by a poly(alkyl-bipyridine) monovalent anion exchange membrane to construct an electrochemical recovery electrolytic cell for electrochemical recovery. The cathode chamber solution and the anode chamber solution in the electrochemical recovery electrolytic cell are 1 mol / L sodium chloride solution. A constant current of 1 C is applied in the electrochemical recovery electrolytic cell for an electrochemical reaction, and the reaction time is 8 h, so that the lithium ions of the waste cathode material dissolve and are enriched in the anode chamber. The electrolysis of water reaction occurs in the cathode chamber, generating hydrogen gas and making the cathode solution alkaline, with pH ≈ 11.

[0033] S2: After the reaction, waste gas containing carbon dioxide and HF (the waste gas used in the examples and comparative examples all comes from the tail gas of a recycling production line workshop of Hunan Bangpu Cycle Technology Co., Ltd.) is introduced into the cathode chamber solution. The volume ratio of carbon dioxide to HF is 5:1, and the mass fractions of carbon dioxide and HF are 20% of the total mass fraction of the waste gas. The introduction rate is 20 mL / min. When the pH of the cathode chamber solution ≤ 7, the introduction of the waste gas containing carbon dioxide and HF is stopped. The tail gas after being absorbed and treated by the cathode chamber solution is collected, and no HF is detected. Only carbon dioxide with a mass fraction of 0.1% is detected in the tail gas.

[0034] S3: After the cathode chamber solution absorbs HF, the formed fluoride ions enter the anode chamber through a monovalent anion exchange membrane and form pure lithium fluoride precipitation with the lithium ions enriched at the anode. The carbon dioxide absorbed by the cathode chamber solution forms carbonate ions. After filtering the precipitate of the cathode chamber solution, high-concentration carbonate wastewater is obtained, and the total carbonate concentration therein is about 10 - 3 mol / L. The ICP (Inductively Coupled Plasma Spectroscopy) is used to measure the lithium ion concentration in the anode chamber before and after the waste gas is introduced. The lithium ion concentration before the waste gas is introduced is 12.36 g / L, and the lithium ion concentration drops to 0.49 g / L after the waste gas is introduced. The decline rate of the lithium ion concentration is 96%. The ICP is used to measure the fluoride ion content in the high-concentration carbonate wastewater, and the concentration is 3.6 mg / L, which meets the wastewater discharge standard.

[0035] Salt lake brine generally needs to use reagents containing carbonate ions for impurity removal. The high-concentration carbonate wastewater obtained in the above steps can be discharged into the salt lake as an impurity removal reagent for the salt lake brine, so that the salt lake brine is preliminarily purified to obtain calcium carbonate and magnesium impurities and the preliminarily purified salt lake brine. This preliminarily purified salt lake brine can be used for electrochemical lithium extraction by deintercalation.

[0036] Example 2

[0037] S1: Using lithium-rich lithium iron phosphate as the anode and lithium-poor lithium iron phosphate as the cathode, the cathode chamber and the anode chamber are separated by a poly(alkyl-bipyridine) monovalent anion exchange membrane to construct an electrochemical deintercalation lithium extraction electrolytic cell for electrochemical lithium extraction reaction. Among them, the cathode chamber solution is alkaline brine, the brine pH = 9.7, and the brine comes from Zabuye Salt Lake; the anode chamber solution is 1 mol / L sodium chloride solution. The electrochemical deintercalation lithium extraction electrolytic cell performs electrochemical lithium extraction at a constant voltage of 0.7 V, so that the lithium ions of the lithium-rich lithium iron phosphate dissolve and are enriched in the anode chamber. When the current drops to 0.2 mA, one lithium extraction process ends; the above lithium extraction process is repeated 3 - 5 times to end the lithium extraction.

[0038] S2: After lithium extraction, waste gas containing carbon dioxide and HF is introduced into the solution in the cathode chamber. The volume ratio of carbon dioxide to HF is 5:1, and the mass fractions of carbon dioxide and HF are 20% of the total mass fraction of the waste gas. The introduction rate is 20 mL / min. When the pH of the solution in the cathode chamber ≤ 7, the introduction of waste gas is stopped. The tail gas after being absorbed and treated by the solution in the cathode chamber is collected. No HF is detected, and only carbon dioxide with a mass fraction of 0.1% is detected in the tail gas.

[0039] S3: Carbon dioxide is absorbed by the brine solution in the cathode chamber. The carbon dioxide absorbed by the solution in the cathode chamber forms carbonate ions and precipitates of some calcium magnesium carbonate and calcium magnesium fluoride impurities. After filtering the precipitate, wastewater with a high concentration of carbonate is obtained. The total carbonate concentration is about 10 -3 mol / L. Fluoride ions pass through the anion exchange membrane into the anode chamber and form pure lithium fluoride precipitate with the lithium ions enriched at the anode. ICP is used to measure the concentration of lithium ions in the anode chamber before and after the introduction of waste gas. The concentration of lithium ions before the introduction of waste gas is 12.47 g / L, and the concentration of lithium ions drops to 0.88 g / L after the introduction of waste gas. The reduction rate of lithium ions is 93%. ICP is used to measure the fluoride ion content in the wastewater with a high concentration of carbonate. The concentration is 5.9 mg / L, which meets the wastewater discharge standard.

[0040] Generally, reagents containing carbonate ions are needed to remove impurities from salt lake brine. The wastewater with a high concentration of carbonate obtained in the above steps can be discharged into the salt lake as a reagent for removing impurities from salt lake brine, so that the salt lake brine is preliminarily purified to obtain calcium magnesium carbonate impurities and preliminarily purified salt lake brine. This preliminarily purified salt lake brine can be used for electrochemical deintercalation lithium extraction, and this preliminarily purified salt lake brine can be introduced into S1 of this embodiment again for electrochemical deintercalation lithium extraction.

[0041] Example 3

[0042] Compared with Example 1, the difference in this example is that the introduction rate of waste gas is 100 mL / min. ICP (Inductively Coupled Plasma Spectroscopy) is used to measure the concentration of lithium ions in the anode chamber before and after the introduction of waste gas. The concentration of lithium ions before the introduction of waste gas is 12.36 g / L, and the concentration of lithium ions drops to 0.56 g / L after the introduction of waste gas. The reduction rate of lithium ion concentration is 95.4%. ICP is used to measure the fluoride ion content in the wastewater with a high concentration of carbonate. The concentration is 4.8 mg / L, which meets the wastewater discharge standard.

[0043] Example 4

[0044] Compared with Example 1, the difference in this example is that the waste gas inlet rate is 1 mL / min. The ICP (Inductively Coupled Plasma Spectroscopy) was used to measure the lithium ion concentration in the anode chamber before and after the waste gas was introduced. The lithium ion concentration before the waste gas was introduced was 12.36 g / L, and after the waste gas was introduced, the lithium ion concentration decreased to 0.482 g / L, with a decrease rate of 96.1% for the lithium ion concentration. The ICP was used to measure the fluoride ion content in the high-concentration carbonate wastewater, and the concentration was 3.6 mg / L, meeting the wastewater discharge standard.

[0045] Example 5

[0046] Compared with Example 1, the difference in this example is that the waste gas inlet rate is 50 mL / min. The ICP (Inductively Coupled Plasma Spectroscopy) was used to measure the lithium ion concentration in the anode chamber before and after the waste gas was introduced. The lithium ion concentration before the waste gas was introduced was 12.36 g / L, and after the waste gas was introduced, the lithium ion concentration decreased to 0.53 g / L, with a decrease rate of 95.7% for the lithium ion concentration. The ICP was used to measure the fluoride ion content in the high-concentration carbonate wastewater, and the concentration was 4.2 mg / L, meeting the wastewater discharge standard.

[0047] Example 6

[0048] Compared with Example 1, the difference in this example is that the volume ratio of carbon dioxide to HF in the waste gas is 1:1. The total carbonate concentration is approximately 1.1*10 -3 mol / L. The ICP (Inductively Coupled Plasma Spectroscopy) was used to measure the lithium ion concentration in the anode chamber before and after the waste gas was introduced. The lithium ion concentration before the waste gas was introduced was 12.36 g / L, and after the waste gas was introduced, the lithium ion concentration decreased to 0.48 g / L, with a decrease rate of 96% for the lithium ion concentration. The ICP was used to measure the fluoride ion content in the high-concentration carbonate wastewater, and the concentration was 6.7 mg / L, meeting the wastewater discharge standard.

[0049] Example 7

[0050] Compared with Example 1, the difference in this example is that the volume ratio of carbon dioxide to HF in the waste gas is 10:1. The total carbonate concentration is approximately 1.3*10 -3 mol / L. The ICP (Inductively Coupled Plasma Spectroscopy) was used to measure the lithium ion concentration in the anode chamber before and after the waste gas was introduced. The lithium ion concentration before the waste gas was introduced was 12.36 g / L, and after the waste gas was introduced, the lithium ion concentration decreased to 0.85 g / L, with a decrease rate of 93.1% for the lithium ion concentration. The ICP was used to measure the fluoride ion content in the high-concentration carbonate wastewater, and the concentration was 3.4 mg / L, meeting the wastewater discharge standard.

[0051] Example 8

[0052] Compared with Example 1, the difference in this example is that the volume ratio of carbon dioxide to HF in the waste gas is 20:1. The total carbonate concentration is about 1.5*10 -3 mol / L. The concentration of lithium ions in the anode chamber before and after the waste gas is introduced is measured by ICP (Inductively Coupled Plasma Spectroscopy). The concentration of lithium ions before the waste gas is introduced is 12.36 g / L, and the concentration of lithium ions drops to 0.94 g / L after the waste gas is introduced. The decline rate of the lithium ion concentration is 92.4%. The fluoride ion content in the high-concentration carbonate wastewater is measured by ICP, and the concentration is 3.2 mg / L, which meets the wastewater discharge standard.

[0053] Example 9

[0054] Compared with Example 1, the only difference in this example is that the volume ratio of carbon dioxide to HF in the waste gas is 50:1, and 0.5% by mass of carbon dioxide is detected in the tail gas. After the cathode chamber solution is filtered and precipitated, high-concentration carbonate wastewater is obtained. The total carbonate concentration is about 10 -3 mol / L. After the waste gas is introduced, the concentration of lithium ions drops from 12.36 g / L to 5.85 g / L, and the decline rate of the lithium ion concentration is 52.7%. The fluoride ion content in the high-carbonate wastewater is measured by ICP, and the concentration is 3.4 mg / L, which meets the wastewater discharge standard.

[0055] In this example, the volume ratio of carbon dioxide is too high and the fluoride ion content in the solution is too low to precipitate lithium ions sufficiently. Similarly, if there is only carbon dioxide gas, the lithium ions in the anode chamber cannot be precipitated either.

[0056] Example 10

[0057] Compared with Example 1, the difference in this example is that in S1, the cathode chamber solution and the anode chamber solution in the electrochemical recovery electrolytic cell are 0.2 mol / L potassium chloride solution, and a 2C constant current is applied in the electrochemical recovery electrolytic cell for the electrochemical reaction, and the reaction time is 10 h.

[0058] Example 11

[0059] Compared with Example 1, the difference in this example is that in S1, the cathode chamber solution and the anode chamber solution in the electrochemical recovery electrolytic cell are 2 mol / L sodium sulfate solution, and a 1C constant current is applied in the electrochemical recovery electrolytic cell for the electrochemical reaction, and the reaction time is 3 h.

[0060] Example 12

[0061] Compared with Example 1, the difference in this example is that in S1, a 2.5V constant voltage is applied in the electrochemical recovery electrolytic cell for the electrochemical reaction, and the reaction time is 3 h.

[0062] Example 13

[0063] Compared with Example 1, the difference in this example lies in that in S1, a constant voltage of 1.5 V is applied in the electrochemical recovery electrolytic cell for the electrochemical reaction, and the reaction time is 10 h.

[0064] Example 14

[0065] Compared with Example 2, the difference in this example lies in that in S1, a constant voltage of 0.9 V is applied in the electrochemical recovery electrolytic cell for the electrochemical reaction.

[0066] Example 15

[0067] Compared with Example 2, the difference in this example lies in that in S1, a constant voltage of 0.1 V is applied in the electrochemical recovery electrolytic cell for the electrochemical reaction.

[0068] Example 16

[0069] Compared with Example 2, the difference in this example lies in that in S1, a constant current of 10 mV is applied in the electrochemical recovery electrolytic cell for the electrochemical reaction, the time for electrochemical lithium extraction is 6 h, and the electrochemical lithium extraction ends after repeating the electrochemical lithium extraction 5 times.

[0070] Example 17

[0071] Compared with Example 2, the difference in this example lies in that in S1, a constant current of 1 mV is applied in the electrochemical recovery electrolytic cell for the electrochemical reaction, the time for electrochemical lithium extraction is 12 h, and the electrochemical lithium extraction ends after repeating the electrochemical lithium extraction 3 times.

[0072] Example 18

[0073] Compared with Example 1, the difference in this example is only that the waste gas gas inlet rate is 500 mL / min, the tail gas after being absorbed and treated by the solution in the cathode chamber is collected, the mass fraction of HF is 8%, and the mass fraction of carbon dioxide is 10%.

[0074] The fluoride ion content in the high-concentration carbonate wastewater is measured by ICP, and the concentration is 18.3 mg / L, which does not meet the wastewater discharge standard.

[0075] The gas rates of Examples 1, 3-5, and 18 are 20, 100, 1, 50, and 500 mL / min, respectively. When the gas rate is 1-100 mL / min, the lithium ion concentration after waste absorption and the effects of carbon dioxide and HF are basically the same. This is because when the pH of the cathode chamber solution is ≤7, the introduction of waste gas containing carbon dioxide and HF is stopped, and the ability of the cathode chamber to absorb carbon dioxide and HF is adapted to 1-100 mL / min. However, in order to save reaction time, the preferred gas flow rate is 20-100 mL / min. However, when the waste introduction rate of Example 18 is excessive, the solution in the cathode chamber cannot absorb so much carbon dioxide and HF, resulting in the re-discharge of excess carbon dioxide and HF.

[0076] Embodiment 19

[0077] The only difference from Example 1 is that the volume ratio of carbon dioxide to HF in the exhaust gas is 1:5. The fluoride ion content in the high-carbonate wastewater was measured by ICP, and the concentration was 20.87 mg / L, which did not meet the wastewater discharge standard.

[0078] In this embodiment, the HF volume ratio is too high, and the fluoride ion content in the cathode chamber is too high. Except for the part that passes through the anion exchange membrane and enters the anode chamber, a large amount of fluoride ions still remain in the cathode chamber, which will increase the fluoride ion content in the wastewater and make it difficult to meet the wastewater discharge standard. Similarly, if there is only HF gas, the fluoride content in the wastewater will be difficult to meet the discharge standard.

[0079] Comparative Example 1

[0080] The only difference from Example 1 is that the anion exchange membrane used is not limited to a monovalent anion exchange membrane. After the cathode chamber solution is filtered and precipitated, wastewater with a high concentration of carbonate is obtained, and the total carbonate concentration is about 10 -3 mo / L. After the exhaust gas was introduced, the concentration of lithium ions dropped from 12.36g / L to 0.97g / L. The fluoride ion content in the high-carbonate wastewater was measured by ICP, and the concentration was 9.8mg / L, which is close to the wastewater discharge standard.

[0081] In this comparative example, an anion exchange membrane through which all anions can pass is used. The anode chamber is a precipitate of lithium carbonate and lithium fluoride, and some lithium ions are combined with carbonate ions, making the lithium salt impure and the fluoride ion content in the cathode chamber increased.

[0082] Comparative Example 2

[0083] The difference from Example 1 is only that the waste gas is directly introduced into an alkaline lithium-containing solution with the same pH (pH = 11) and lithium concentration (12.36 g / L), without using an electrochemical device and a monovalent anion exchange membrane. After the waste gas is introduced, the lithium ion concentration drops to 3.18 g / L. The fluoride ion content in the high carbonate wastewater is measured by ICP, and the concentration is 10.28 mg / L, which does not meet the wastewater discharge standard.

[0084] In this comparative example, since fluoride ions cannot be enriched on one side, there are fewer lithium fluoride precipitates, and the lithium-containing precipitate is a mixture of lithium carbonate and lithium fluoride, resulting in impure lithium salts and a high fluoride ion content in the solution, which does not meet the wastewater discharge standard.

Claims

1. A method for recycling lithium from batteries, characterized in that: It includes the following steps: Using a lithium-rich battery material as the anode, a lithium-poor battery material as the cathode, and separating them with a monovalent anion exchange membrane between the anode and the cathode to form an anode chamber and a cathode chamber. Add an anode chamber solution and a cathode chamber solution to the anode chamber and the cathode chamber respectively to form an electrolytic cell; Use the electrolytic cell to carry out an electrochemical reaction to extract lithium, and then introduce a gas containing carbon dioxide and hydrogen fluoride into the cathode chamber solution of the electrolytic cell. Lithium fluoride precipitate is obtained in the anode chamber, and carbonate wastewater is obtained in the cathode chamber.

2. The method for recycling lithium from a battery according to claim 1, characterized in that, In the gas containing carbon dioxide and hydrogen fluoride, the volume ratio of carbon dioxide to hydrogen fluoride is (50 - 5):(1 - 5); the flow rate of the gas containing carbon dioxide and hydrogen fluoride is 1 - 500 mL / min.

3. The method for recycling lithium from a battery according to claim 2, characterized in that, In the gas containing carbon dioxide and hydrogen fluoride, the volume ratio of carbon dioxide to hydrogen fluoride is (10 - 5):1; the flow rate of the gas containing carbon dioxide and hydrogen fluoride is 20 - 100 mL / min.

4. The method for recycling lithium from a battery according to claim 1, characterized in that, The concentration of cations in the cathode chamber solution is 0.2 - 2 mol / L.

5. The method for recycling lithium from a battery according to claim 1, characterized in that, The concentration of cations in the anode chamber solution is 0.2 - 2 mol / L.

6. The method for recycling lithium from a battery according to claim 1, characterized in that, The anode chamber solution includes at least one of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate.

7. The method for recycling lithium from a battery according to claim 1, wherein, The lithium-rich battery material includes at least one of lithium-rich ion sieves and lithium-ion battery cathode materials; the lithium-poor battery material includes at least one of lithium-poor ion sieves and inert electrodes; the cathode chamber solution includes at least one of sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, and alkaline brine.

8. The method for recycling lithium from a battery according to claim 7, characterized in that, When the lithium-rich battery material is a lithium-rich ion sieve, the lithium-poor battery material is a lithium-poor ion sieve, and the cathode chamber solution is alkaline brine, a constant voltage is applied to the electrolytic cell, and the constant voltage is 0.1V - 0.9V. When the current of the electrolytic cell ≤ 0.2 mA, the electrochemical lithium extraction ends.

9. The method for recycling lithium from a battery according to claim 7, characterized in that, When the lithium-rich battery material is a lithium-rich ion sieve, the lithium-poor battery material is a lithium-poor ion sieve, and the cathode chamber solution is alkaline brine, a constant current is applied to the electrolytic cell, and the constant current is 1 mA - 10 mA. The time for electrochemical lithium extraction is 6 - 12 h. After repeating the electrochemical lithium extraction 3 - 5 times, the electrochemical lithium extraction ends.

10. The method for recycling lithium from a battery according to claim 7, characterized in that, When the lithium-poor battery material is a lithium-ion battery cathode material, the lithium-poor battery material is an inert electrode, and the cathode chamber solution includes at least one of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate, a constant current or a constant voltage is applied to the electrolytic cell.

11. The method for recycling lithium from a battery according to claim 10, wherein, The constant current is 0.1C - 2C, and the time for electrochemical lithium extraction is 3 - 10 h.

12. The method for recycling lithium from a battery according to claim 10, wherein The constant voltage is 1.5V - 2.5V; the time for electrochemical lithium extraction is 3 - 10 h; when the pH value of the cathode chamber solution ≤ 7, stop introducing the gas containing carbon dioxide and hydrogen fluoride.

13. The method for recycling lithium from a battery according to claim 7, characterized in that, The lithium-rich ion sieve includes lithium-rich lithium iron phosphate; the lithium-poor ion sieve includes lithium-poor lithium iron phosphate.

14. The method for recycling lithium from a battery according to claim 7, characterized in that, The lithium-ion battery cathode material includes a lithium cobalt oxide battery cathode material; the inert electrode includes at least one of a calomel electrode and a carbon electrode.

15. The method for recycling lithium from a battery according to claim 7, wherein The pH value of the alkaline brine is 9 to 11.

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