A hydrophobic selective permeation membrane for synchronously capturing co2 and recovering lithium ions in lithium batteries, a preparation method and applications thereof

Abstract

The application provides a hydrophobic selective permeation membrane for synchronously capturing CO2 and recovering lithium ions in lithium batteries, a preparation method and application thereof. The hydrophobic selective permeation membrane comprises a cobalt-based two-dimensional conductive metal organic framework hydrophobic support layer and an ionic liquid polyamide lithium ion selective layer. The application combines selective recovery of lithium ions in a waste battery positive electrode and CO2 capture, realizes the effect of synchronous recovery-carbon reduction, optimizes the traditional metal leaching recovery pretreatment into electrochemical direct recovery, optimizes the traditional TMC aqueous phase interfacial polymerization into TMC-ionic liquid interfacial reaction, combines the electrostatic spinning technology of the conductive MOF material, simplifies the recovery process, realizes a green and environmentally friendly and reusable recovery mode, improves the recovery selectivity and recovery efficiency of the lithium ions, and synchronously realizes carbon capture.

Description

Technical Field

[0001] This invention belongs to the field of recycling cathode metals from waste lithium batteries, and specifically relates to a hydrophobic selective permeable membrane that simultaneously captures CO2 and recovers lithium ions from lithium batteries, its preparation method, and its application. Background Technology

[0002] In recent years, with the rapid development of new energy vehicles and mobile electronic devices, the demand for lithium-ion batteries has increased significantly. Lithium in nature is mainly found in salt lake brines and seawater, but the development of liquid lithium resources still faces problems such as high energy consumption and low efficiency, and my country has relied on imports for lithium resources for many years. The lithium content in waste lithium batteries is also significant. Currently, most research and industrial applications use pyrometallurgical and hydrometallurgical methods for recycling, but lithium-ion recycling has low selectivity and complex processes. Furthermore, using acid leaching and alkaline leaching methods to recycle waste lithium batteries can easily cause environmental pollution.

[0003] The prior art disclosed in patent CN102373341A uses a reverse osmosis membrane to recover lithium ions from low-concentration seawater. However, even if the selectively permeable membrane is doped with ionic liquid, the Faraday efficiency in the electrorecovery process cannot be guaranteed. In addition, the recovered product, lithium hydroxide, is in the form of a recovery liquid and cannot be directly separated, which is not conducive to recovery. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a hydrophobic selective permeable membrane for simultaneously capturing CO2 and recovering lithium ions from lithium batteries, its preparation method, and its application. This method features strong conductivity, high Faraday efficiency, and strong lithium ion selectivity, enabling simultaneous carbon capture and the generation of Li2CO3 precipitate for easy lithium separation.

[0005] In a first aspect, the present invention provides a hydrophobic selective permeable membrane for simultaneously capturing CO2 and recovering lithium ions from a lithium battery, comprising a cobalt-based two-dimensional conductive metal-organic framework hydrophobic support layer and an ionic liquid polyamide lithium ion selective layer.

[0006] A second aspect of the present invention provides a method for preparing a hydrophobically selectively permeable membrane for simultaneously capturing CO2 and recovering lithium ions from a lithium battery, comprising the following steps:

[0007] Step (1) Mix HAB and Co(II) salt in water to allow them to undergo a complexation reaction. Slowly add NH3·H2O solution to the mixed solution and continue stirring to dissolve until a deep blue precipitate of Co-HAB is formed. After centrifuging to remove the supernatant, dry for 10 h to obtain a cobalt-based two-dimensional conductive metal-organic framework.

[0008] Step (2) Add PVDF-co-HFP, the cobalt-based two-dimensional conductive metal-organic framework obtained in step (1) and acetone to N,N-dimethylformamide, stir magnetically to dissolve, and obtain spinning solution. Electrospin the solution to obtain a hydrophobic support layer of the cobalt-based two-dimensional conductive metal-organic framework.

[0009] Step (3) Based on the cobalt-based two-dimensional conductive metal-organic framework hydrophobic support layer obtained in step (2), an interfacial selective membrane is polymerized. Polyethyleneimine (PEI) is used as an amine monomer. Piperazine (PIP) and PEI are dissolved in the ionic liquid [C2mim]BF4. After sonicating the mixed solution, it is placed on the cobalt-based two-dimensional conductive metal-organic framework hydrophobic support layer in step (2), left to stand naturally, the remaining solution is removed, and it is dried to obtain the ionic liquid diamine layer. TMC is dissolved in n-hexane, the mixed solution is placed on the ionic liquid diamine layer to react, and after air drying, it is placed in an oven to cure, thus obtaining the ionic liquid polyamide lithium ion selective layer polymerized on the cobalt-based two-dimensional conductive metal-organic framework hydrophobic support layer. At this point, the preparation of the hydrophobic lithium ion selective permeable membrane is completed.

[0010] Preferably, in step (1), the Co(II) salt is Co(NO3)2, and the mass ratio of HAB to Co(NO3)2 is (1-3):1, more preferably 2:1.

[0011] Preferably, in step (2), the mass ratio of PVDF-co-HFP to DMF is (3-7):16, more preferably 5:16; the mass ratio of cobalt-based two-dimensional conductive metal-organic framework to DMF is (5-8):16, more preferably 5:16; and the mass ratio of acetone to DMF is 1:(3-5), more preferably 1:4.

[0012] Preferably, in step (3), the mass ratio of PIP, PEI, and ionic liquid [C2mim]BF4 is (0.5-2):(0.5-2):1, and the standing time is 5-20 min. The mass concentration of the hexane solution of TMC is 0.05-0.5 wt%, more preferably 0.1 wt%; the reaction time between the mixed solution and the diamine layer in step (3) is 40-80 s, more preferably 60 s.

[0013] A third aspect of the present invention provides an apparatus for simultaneously capturing CO2 and recovering lithium ions from a lithium battery, comprising a hydrophobic selectively permeable membrane for simultaneously capturing CO2 and recovering lithium ions from a lithium battery, a working electrode, an electrolyte, and an external power supply.

[0014] A fourth aspect of the present invention provides a method for using a device for simultaneously capturing CO2 and recovering lithium ions from a lithium battery, comprising the following steps:

[0015] Step (1) The lithium hydroxide electrolyte is placed in a PVDF hollow mold wrapped with a hydrophobic selective permeable membrane that simultaneously captures CO2 and recovers lithium ions from the lithium battery. The NCM523 ternary lithium battery is wound between the negative electrode membrane and the positive electrode.

[0016] Step (2) Use Cu-Pt electrode as working electrode, connect to external power supply, and use a rotating table to fully enrich the metallic lithium in waste NCM523 ternary lithium battery into electrolyte.

[0017] Step (3) The device continuously introduces CO2 gas into the lithium hydroxide electrolyte, uses the alkaline electrolyte to capture CO2, and generates Li2CO3 precipitate, so as to simultaneously capture CO2 and promote the efficient recovery of lithium ions in the positive electrode of waste lithium batteries.

[0018] Preferably, in step (1) of the method of use, the concentration of lithium hydroxide electrolyte is 50-80 mmol / L, more preferably 70 mmol / L.

[0019] Preferably, in step (2) of the method of use, the Pt electrode is inserted into the lithium hydroxide electrolyte, and the external power supply voltage is maintained above 3.5V, more preferably 5V.

[0020] Preferably, in step (3) of the method of use, the CO2 concentration is 1000 mg / L or higher, more preferably 2000 mg / L, and the electrolyte can be observed to change from turbidity to the formation of white precipitate.

[0021] This invention provides a novel method for simultaneously capturing CO2 and selectively recovering lithium ions from lithium batteries. Addressing the environmental pollution caused by metal leaching and poor selective recovery in current waste lithium battery recycling methods, this invention utilizes an electrochemical method for direct recovery of the positive electrode combined with an ion-selective permeable membrane. The prepared lithium-ion selective permeable membrane, PVDF-co-HFP material, can be used in electrospinning to prepare a superhydrophobic membrane. The addition of Co-HAB improves the Faraday efficiency, a key indicator in the electrochemical reaction. The membrane's conductivity is enhanced by the occupancy and orientation of the metal ion's d orbitals and the interaction between Co(II) ions and ligands, thereby increasing the electron transfer rate on the selectively permeable membrane during the electrochemical process and ultimately improving the Faraday efficiency of the reaction. The Donnan effect on the ionic liquid diamine membrane enhances the permeability of monovalent ions and the repulsion of high-valent ions. Unlike traditional water interface diffusion, TMC diffusion into the ionic liquid improves interface stability and cross-linking, thereby increasing the reusability of the device. While lithium ions are enriched in the electrolyte, CO2 is captured to form Li2CO3 precipitate. This method combines lithium battery recovery and CO2 capture, enabling effective selective recovery of lithium ions from the positive electrode of lithium batteries and continuous carbon capture.

[0022] Compared with traditional processes, this invention has the following advantages:

[0023] (1) This invention is based on the selective recovery of lithium ions using an electrochemical method. It achieves highly selective and high Faradaic efficiency recovery of spent lithium battery cathodes through the application of conductive MOF materials and ionic liquids in electrospun membranes, converting spent lithium batteries into pure Li2CO3 powder and clean energy -H. 2.

[0024] (2) Traditional lithium battery recycling requires battery crushing and chemical leaching, resulting in low lithium-ion selectivity, environmental damage, and high labor and material costs. This invention recycles lithium-ion by directly winding the waste electrode positive electrode between the positive and negative electrodes, eliminating the need for chemical leaching of metal ions from the electrodes. The lithium-ion recycling process is highly selective, simple, environmentally friendly, and reusable.

[0025] (3) This invention introduces waste CO2 to react with the electrolyte to generate Li2CO3 precipitate, which promotes the separation of products in the lithium recovery system and achieves the purpose of simultaneous carbon capture and lithium resource recovery, reflecting the concept of efficient resource utilization and environmental protection. Attached Figure Description

[0026] Figure 1 The images show the SEM and EDS images of the ionic liquid polyamide lithium-ion selective membrane (P@P-TMC / Co-HAB membrane). Among them, (a) is the SEM image of the interfacial polymerization surface of the P@P-TMC / Co-HAB membrane, (b) is the SEM image of the non-interfacial polymerization surface of the P@P-TMC / Co-HAB membrane, (c) is the SEM image of the cross-section of the P@P-TMC / Co-HAB membrane, and (d) is the EDS image of the cross-section of the P@P-TMC / Co-HAB membrane.

[0027] Figure 2 The figures show the water contact angles of the membranes. (a) shows the water contact angle of the cobalt-based two-dimensional conductive metal-organic framework hydrophobic support layer (Co-HAB layer), and (b) shows the water contact angle of the P@P-TMC / Co-HAB membrane.

[0028] Figure 3 The graph shows the change in lithium ion concentration over time in the recovered cathode electrolyte of the P@P-TMC / Co-HAB membrane prepared in Example 1.

[0029] Figure 4 XRD patterns of the positive electrode of waste NCM523 batteries before and after recycling.

[0030] Figure 5 The graph shows the changes in lithium ion recovery rate and selectivity in the catholyte of the P@P-TMC / Co-HAB membrane prepared in Example 1 as a function of the number of cycles.

[0031] Figure 6 The graph shows the change of Faraday efficiency with the number of cycles during the recovery process in Example 1.

[0032] Figure 7 This is a schematic diagram of the apparatus for selectively recycling lithium ions from the positive electrode of waste lithium batteries in this invention. Detailed Implementation

[0033] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0034] Example 1

[0035] Step 1: Mix 40 mg HAB and 20 mg Co(NO3)2 in 10 mL of water to allow them to undergo a complexation reaction. Slowly add 60 μL of 6 M NH3·H2O solution to the mixed solution and continue stirring to dissolve until a dark blue precipitate of Co-HAB is formed.

[0036] Step 2: Add 2g PVDF-co-HFP, 2g Co-HAB and 1.6g acetone to 6.4g DMF, stir magnetically at 60℃ for 12 h, and electrospin at 20 kV at 1 mL / h to obtain Co-HAB hydrophobic base film.

[0037] Step 3: Interfacially polymerize an ion-selective membrane on the hydrophobic base membrane; add 0.6 g PIP and 0.4 g PEI to 30 g [C2mim]BF4 solution, place the mixed solution on the Co-HAB hydrophobic base membrane, blow dry, and then diffuse 0.1 wt% TMC n-hexane solution into the [C2mim]BF4 solution. After air drying, solidify to obtain the ion liquid polyamide lithium ion-selective membrane.

[0038] Step 4: Use a Cu-Pt electrode as the working electrode, with the negative electrode immersed in a 70 mmol / L lithium hydroxide electrolyte. The electrolyte is contained in a PVDF hollow mold wrapped with the ionic liquid polyamide lithium ion selective membrane from step (1). Wrap the NCM523 ternary lithium battery between the negative electrode membrane and the Cu electrode. The external power supply maintains an input voltage of not less than 3.5V. Under the action of the rotating stage, the negative electrode enriches monovalent lithium ions in the electrolyte and continuously captures CO2 with a concentration of not less than 1000 mg / L, forming a white LiCO3 precipitate.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

[0040] Figure 1 The results show that: Figures (a) and (b) show that an ionic liquid polyamide layer was obtained after interfacial polymerization, and the polyamide particles on the surface of the interfacial polymerization surface are more obvious. Figures (c) and (d) show that the polyamide layer is uniformly attached to the surface of the cobalt-based two-dimensional conductive metal-organic framework hydrophobic support layer (Co-HAB layer), and due to the large pore size of the Co-HAB layer, a small amount of interfacial polymerization also occurred on the reverse side.

[0041] Figure 2 This indicates that both the Co-HAB layer and the P@P-TMC / Co-HAB membrane have strong hydrophobicity, enabling the P@P-TMC / Co-HAB membrane to store the electrolyte in the hollow mold.

[0042] Figure 3 This indicates that the developed selective recycling device can effectively recover lithium ions from waste lithium batteries in a short period of time.

[0043] Figure 4 This indicates that the selective recovery device successfully completed the lithium extraction process during electrochemical reaction. The increased peak spacing between (006) and (012) indicates a change in the layered structure. The decrease in (003) is mainly due to the decrease in the Li / Ni ratio, which also indicates that the crystal structure has been destroyed.

[0044] Figure 5 This indicates that the developed selective recycling device can efficiently recover lithium ions from waste lithium batteries, with a lithium ion recovery rate of approximately 93.3% and a lithium ion selectivity of approximately 99.8%.

[0045] Figure 6 The results show that the selective recycling device can efficiently recover lithium ions from waste lithium batteries, with a Faraday efficiency of approximately 96.7% during the electrochemical recycling process.

[0046] Figure 7 This demonstrates the reaction principle and process of the selective recovery device.

Claims

1. A method for preparing a hydrophobically selectively permeable membrane for simultaneously capturing CO2 and recovering lithium ions from a lithium battery, characterized in that, Includes the following steps: Step (1) Mix HAB and Co(II) salt in water to allow them to undergo a complexation reaction. Slowly add NH3·H2O solution to the mixed solution and continue stirring to dissolve until a dark blue precipitate of Co-HAB is formed. After centrifuging to remove the supernatant, dry for 10 h to obtain a cobalt-based two-dimensional conductive metal-organic framework. Step (2) Add PVDF-co-HFP, the cobalt-based two-dimensional conductive metal-organic framework obtained in step (1) and acetone to N,N-dimethylformamide, stir magnetically to dissolve, and obtain spinning solution. Electrospin the solution to obtain a hydrophobic support layer of the cobalt-based two-dimensional conductive metal-organic framework. Step (3) Based on the cobalt-based two-dimensional conductive metal-organic framework hydrophobic support layer obtained in step (2), an interfacial selective membrane is polymerized. Polyethyleneimine is used as an amine monomer. Piperazine and polyethyleneimine are dissolved in the ionic liquid [C2mim]BF4. The mixed solution is sonicated and placed on the cobalt-based two-dimensional conductive metal-organic framework hydrophobic support layer in step (2). It is left to stand naturally, the remaining solution is removed, and it is dried to obtain the ionic liquid diamine layer. TMC is dissolved in n-hexane. The mixed solution is placed on the ionic liquid diamine layer for reaction and air-dried. It is then placed in an oven for curing to obtain the ionic liquid polyamide lithium-ion selective layer polymerized on the cobalt-based two-dimensional conductive metal-organic framework hydrophobic support layer. Thus, the preparation of the hydrophobic selective permeable membrane for simultaneously capturing CO2 and recovering lithium ions from lithium batteries is completed.

2. The method for preparing a hydrophobically selectively permeable membrane for simultaneously capturing CO2 and recovering lithium ions from a lithium battery according to claim 1, characterized in that, In step (1), the Co(II) salt is Co(NO3)2, and the mass ratio of HAB to Co(NO3)2 is (1-3):

1.

3. The method for preparing a hydrophobically selectively permeable membrane for simultaneously capturing CO2 and recovering lithium ions from a lithium battery according to claim 1, characterized in that, In step (2), the mass ratio of PVDF-co-HFP to DMF is (3-7):16, the mass ratio of cobalt-based two-dimensional conductive metal-organic framework to DMF is (5-8):16, and the mass ratio of acetone to DMF is 1:(3-5).

4. The method for preparing a hydrophobically selectively permeable membrane for simultaneously capturing CO2 and recovering lithium ions from a lithium battery according to claim 1, characterized in that, In step (3), the mass ratio of piperazine, polyethyleneimine, and ionic liquid [C2mim]BF4 is (0.5-2):(0.5-2):75, the standing time is 5-20 min, the mass concentration of TMC in n-hexane solution is 0.05-0.5 wt%, and the reaction time between the mixed solution and the ionic liquid diamine layer in step (3) is 40-80 s.

5. A hydrophobically selectively permeable membrane for simultaneously capturing CO2 and recovering lithium ions from lithium batteries, characterized in that, A hydrophobic selectively permeable membrane for simultaneously capturing CO2 and recovering lithium ions from a lithium battery, prepared by the preparation method according to any one of claims 1-4.

6. A device for simultaneously capturing CO2 and recovering lithium ions from a lithium battery, characterized in that, It includes the hydrophobic selectively permeable membrane for simultaneously capturing CO2 and recovering lithium ions from lithium batteries as described in claim 5, the working electrode, the electrolyte, and the external power supply.

7. A method of using the apparatus for simultaneously capturing CO2 and recovering lithium ions from a lithium battery as described in claim 6, characterized in that, Includes the following steps: Step (1) The lithium hydroxide electrolyte is placed in a PVDF hollow mold wrapped with a hydrophobic selective permeable membrane that simultaneously captures CO2 and recovers lithium ions from the lithium battery. The NCM523 ternary lithium battery is wound between the negative electrode membrane and the positive electrode. Step (2) Use Cu-Pt electrode as working electrode, connect to external power supply, and use a rotating table to fully enrich the metallic lithium in waste NCM523 ternary lithium battery into electrolyte. Step (3) The device continuously introduces CO2 gas into the lithium hydroxide electrolyte, uses the alkaline electrolyte to capture CO2, and generates Li2CO3 precipitate, so as to simultaneously capture CO2 and promote the efficient recovery of lithium ions in the positive electrode of waste lithium batteries.

8. The method of using the apparatus for simultaneously capturing CO2 and recovering lithium ions from a lithium battery as described in claim 7, characterized in that, In step (1) of the method of use, the concentration of lithium hydroxide electrolyte is 50-80 mmol / L.

9. The method of using the apparatus for simultaneously capturing CO2 and recovering lithium ions from a lithium battery as described in claim 7, characterized in that, In step (2) of the method of use, the Pt electrode is inserted into the lithium hydroxide electrolyte, and the external power supply voltage is maintained above 3.5V.

10. The method of using the apparatus for simultaneously capturing CO2 and recovering lithium ions from a lithium battery as described in claim 7, characterized in that, In step (3) of the method of use, when the CO2 concentration is above 1000 mg / L, it can be observed that the electrolyte changes from turbidity to the formation of a white precipitate.

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