Hydrophobic selective permeable membrane for synchronously capturing CO2 and recycling lithium ions in lithium battery, preparation method and application thereof

Abstract

The invention provides a hydrophobic selective permeable membrane for synchronously capturing CO2 and recycling lithium ions in a lithium battery, and a preparation method and application thereof. The hydrophobic selective permeable membrane comprises a cobalt-based two-dimensional conductive metal organic framework hydrophobic supporting layer and an ionic liquid polyamide lithium ion selection layer. Selective recovery of lithium ions in the positive electrode of the waste battery and CO2 capture are combined, the effect of synchronous recovery-carbon reduction is achieved, traditional metal leaching recovery pretreatment is optimized into electrochemical direct recovery, traditional TMC water-phase interfacial polymerization is optimized into TMC-ionic liquid interface reaction, and the conductive MOF material electrostatic spinning technology is combined, so that the recovery-carbon reduction effect is achieved. The method simplifies the recovery process, realizes an environment-friendly and reusable recovery mode, improves the recovery selectivity and recovery efficiency of lithium ions, and synchronously realizes carbon capture.

Description

Technical Field

[0001] The present invention belongs to the field of recycling positive electrode metals of waste lithium batteries, and particularly relates to a method for synchronously capturing CO 2 And a hydrophobic selective permeable membrane for recovering lithium ions in lithium batteries, and its preparation method and application. Background Art

[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 mainly exists in salt lake brine and seawater, but the development of liquid lithium resources still has problems such as high energy consumption and low efficiency. my country's lithium resources have been relying on imports for many years. The lithium content in waste lithium batteries cannot be ignored. At present, most research and industrial applications use pyrometallurgical recovery and wet recovery, but the recovery selectivity of lithium ions is low and the process is complicated. The use of acid leaching and alkaline leaching methods to recycle waste lithium batteries is prone to environmental pollution.

[0003] Patent CN102373341A is disclosed in the prior art, which uses a reverse osmosis membrane to recover lithium ions from low-concentration seawater. However, even if the selective permeable membrane is doped with an ionic liquid, the Faraday efficiency in the electrical recovery process cannot be guaranteed. At the same time, 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] In order to solve the defects of the prior art, the present invention provides a method for synchronously capturing CO 2 Hydrophobic selective permeable membrane for recovering lithium ions in lithium batteries, preparation method and application thereof, the method has strong conductivity, high Faraday efficiency, strong lithium ion selectivity, and can simultaneously complete carbon capture and generate Li 2 CO 3 The precipitation facilitates the separation of lithium.

[0005] In a first aspect of the present invention, a method for synchronously capturing CO 2 A hydrophobic selective permeable membrane for recovering lithium ions in lithium batteries, comprising a cobalt-based two-dimensional conductive metal organic framework hydrophobic support layer and an ionic liquid polyamide lithium ion selective layer.

[0006] The second aspect of the present invention provides a method for synchronously capturing CO 2 A method for preparing a hydrophobic selective permeable membrane for recovering lithium ions in a lithium battery comprises the following steps:

[0007] Step (1) HAB and Co(II) salt are mixed in water to allow them to undergo a complex reaction, and NH 3 ·H 2O solution and continued stirring to dissolve until a dark blue precipitate of Co-HAB was generated, and the supernatant was removed by centrifugation and dried for 10 h to obtain a cobalt-based two-dimensional conductive metal-organic framework;

[0008] Step (2) adding polytetrafluoroethylene-hexafluoropropylene (PVDF-co-HFP), the cobalt-based two-dimensional conductive metal organic framework obtained in step 1 and acetone to N,N-dimethylformamide, dissolving by magnetic stirring to obtain a spinning solution, and electrospinning to obtain a cobalt-based two-dimensional conductive metal organic framework hydrophobic support layer;

[0009] Step (3) interfacially polymerizes a selective membrane on the basis of the cobalt-based two-dimensional conductive metal organic framework hydrophobic support layer obtained in step (2), using polyethyleneimine (PEI) as an amine monomer, dissolving piperazine (PIP) and PEI in an ionic liquid [C 2 mim]BF 4 In the step (2), the mixed solution is ultrasonically treated and then placed on the cobalt-based two-dimensional conductive metal organic framework hydrophobic support layer, and then left to stand naturally to remove the remaining solution and blow dry to obtain an ionic liquid diamine layer. TMC is dissolved in n-hexane, and the mixed solution is placed on the ionic liquid diamine layer to react and air-dry, and then placed in an oven for curing to obtain an 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, the Co(II) salt in step (1) is Co(NO 3 ) 2 , HAB and Co(NO 3 ) 2 The mass ratio is (1-3):1, and more preferably 2:1.

[0011] Preferably, in the step (2), the mass ratio of PVDF-co-HFP to DMF is (3-7):16, more preferably 5:16; the mass ratio of Co-HAB to DMF in step 1 is (5-8):16, more preferably 5:16; the mass ratio of acetone to DMF is 1:(3-5), more preferably 1:4.

[0012] Preferably, in step (3), PIP, PEI, ionic liquid [C 2 mim]BF 4 The mass ratio of is (0.5-2): (0.5-2): 1, and the standing time is 5-20 min. The mass concentration of the n-hexane solution of TMC is 0.05-0.5wt%, more preferably 0.1wt%; the reaction time of the mixed solution and the diamine layer in step (3) is 40-80s, more preferably 60s.

[0013] The third aspect of the present invention provides a method for synchronously capturing CO 2 and devices for recycling lithium ions from lithium batteries, including simultaneous capture of CO 2 And a hydrophobic selective permeable membrane, a working electrode, an electrolyte and an external power supply for recycling lithium ions in a lithium battery.

[0014] A fourth aspect of the present invention provides a method for synchronously capturing CO 2 And an application method of a lithium ion device for recycling lithium batteries, comprising the following steps:

[0015] Step (1) placing lithium hydroxide electrolyte in a container having a structure capable of synchronously capturing CO 2 In a PVDF hollow mold wrapped with a hydrophobic selective permeable membrane for recycling lithium ions in lithium batteries, an NCM523 ternary lithium battery is wound between the negative electrode membrane and the positive electrode;

[0016] Step (2) uses a Cu-Pt electrode as a working electrode, connects to an external power source, and fully enriches the metallic lithium in the waste NCM523 ternary lithium battery into the electrolyte through a rotating table;

[0017] The device of step (3) is provided by 2 The gas is continuously passed into the lithium hydroxide electrolyte, and the alkaline electrolyte is used to capture CO 2 , generating Li 2 CO 3 precipitation to simultaneously capture CO 2 And promote the efficient recovery of lithium ions in the positive electrode of waste lithium batteries.

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

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

[0020] Preferably, in step (3), CO 2 When the concentration is 1000 mg / L or more, more preferably 2000 mg / L, it can be observed that the electrolyte changes from turbidity to the formation of white precipitation.

[0021] The present invention provides a novel synchronous capture CO 2And the method of selectively recovering lithium ions from lithium batteries. Based on the current characteristics of metal leaching pollution and poor selective recovery in the recycling of waste lithium batteries, the electrochemical direct recovery method of the positive electrode can be combined with an ion selective permeable membrane for recovery. The prepared lithium ion selective permeable membrane, PVDF-co-HFP material can be used to prepare a superhydrophobic membrane in electrospinning. The key indicator in the electrochemical reaction, the Faraday efficiency, is improved by adding Co-HAB. It depends on the occupation and orientation of the metal ion d orbital and the interaction between Co (Ⅱ) ions and ligands to enhance the conductivity of the membrane, increase the electron transfer rate on the selective permeable membrane during the electrochemical process, and thus improve the Faraday efficiency of the reaction. The Donnan effect on the ionic liquid diamine membrane enhances the permeability of monovalent ions and the rejection of high-valent ions. Unlike the traditional water interface diffusion, the diffusion of TMC into the ionic liquid improves the interface stability and cross-linking, improves the reusability of the device, and completes the CO enrichment while the lithium ions are enriched in the electrolyte. 2 The capture of Li 2 CO 3 Precipitation, this method recovers lithium batteries and CO 2 The combination of capture and selective recovery of lithium ions from the positive electrode of lithium batteries and continuous carbon capture can be effectively achieved.

[0022] Compared with the traditional process, the present invention has the following advantages:

[0023] (1) The present invention selectively recovers lithium ions based on electrochemical methods, and realizes high selectivity and high Faraday efficiency recycling of waste lithium battery positive electrodes by using conductive MOF materials and ionic liquids in electrospinning membranes, thereby converting waste lithium batteries into pure Li 2 CO 3 Powder and Clean Energy-H 2.

[0024] (2) Traditional lithium battery recycling requires battery crushing and chemical leaching, which results in low lithium ion selectivity, environmental damage, and high manpower and material costs. The present invention recycles waste positive electrodes by directly winding them between the positive and negative electrodes. It does not require the use of chemical substances to leach metal ions in the electrodes. The lithium ion recovery selectivity is strong, the process is simple, environmentally friendly, and can be reused.

[0025] (3) The present invention introduces waste CO 2 Reacts with the electrolyte to generate Li 2 CO 3 Precipitation promotes product separation in the lithium recovery system, achieves the purpose of simultaneous carbon capture and lithium resource recovery, and embodies the concept of efficient resource utilization and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1These are the SEM and EDS images of the ionic liquid polyamide lithium ion selective membrane (P@P-TMC / Co-HAB membrane), where (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 water contact angle diagram of the membrane. (a) is the water contact angle diagram of the cobalt-based two-dimensional conductive metal organic framework hydrophobic support layer (Co-HAB layer), and (b) is the water contact angle diagram of the P@P-TMC / Co-HAB membrane.

[0028] Figure 3 This is a graph showing the change in lithium ion concentration in the cathode electrolyte recovered by the P@P-TMC / Co-HAB membrane prepared in Example 1 over time.

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

[0030] Figure 5 This is a graph showing the change in lithium ion recovery rate and selectivity in the cathode liquid of the P@P-TMC / Co-HAB membrane prepared in Example 1 as a function of the number of cycles.

[0031] Figure 6 This is a graph showing the change in Faraday efficiency during the recovery process of Example 1 as a function of the number of cycles.

[0032] Figure 7 It is a schematic diagram of the device for selectively recovering lithium ions from the positive electrode of waste lithium batteries in the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0034] Example 1

[0035] Step 1: 40 mg HAB and 20 mg Co(NO 3 ) 2 Mix them in 10 mL of water to allow them to undergo complexation reaction, and slowly add 60 μL of 6 M NH 3 ·H 2O solution and continue to stir and dissolve until a dark blue precipitate of Co-HAB is formed.

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

[0037] Step 3: On the basis of the hydrophobic base membrane, an ion selective membrane is interfacially polymerized; 0.6 g PIP and 0.4 g PEI are added to 30 g [C 2 mim]BF 4 The mixed solution was placed on the Co-HAB hydrophobic base film and then dried to diffuse the 0.1wt% TMC n-hexane solution into [C 2 mim]BF 4 The solution was air-dried and then solidified to obtain an ionic liquid polyamide lithium ion selective membrane.

[0038] Step 4: A Cu-Pt electrode is used as a working electrode, wherein the negative electrode is immersed in a 70 mmol / L lithium hydroxide electrolyte, the electrolyte is contained in a PVDF hollow mold wrapped with an ionic liquid polyamide lithium ion selective membrane in step (1), and an NCM523 ternary lithium battery is wound between the negative electrode membrane and the Cu electrode. The external power supply maintains an input voltage of not less than 3.5 V. The negative electrode is enriched with positive monovalent lithium ions in the electrolyte under the action of a rotating table, and at the same time, CO with a concentration of not less than 1000 mg / L is continuously captured. 2 , forming white LiCO 3 precipitation.

[0039] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and equivalent changes made by using the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

[0040] Figure 1It shows that: from (a) and (b), it can be found that the ionic liquid polyamide layer is obtained after interfacial polymerization, and the polyamide particles on the surface of the interfacial polymerization surface are more obvious. From (c) and (d), it can be found 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 occurs on the reverse side.

[0041] Figure 2 It shows that both the Co-HAB layer and the P@P-TMC / Co-HAB membrane are highly hydrophobic, allowing the P@P-TMC / Co-HAB membrane to store the electrolyte in the hollow mold.

[0042] Figure 3 It shows that the selective recovery device can effectively recover lithium ions from waste lithium batteries in a short time.

[0043] Figure 4 It shows that the selective recovery device has completed the extraction of lithium in the electrochemical process. The distance between the (006) and (012) peaks has increased, indicating that the layered structure has changed. The decrease in (003) is mainly caused by the decrease in the Li / Ni ratio, which also indicates that the crystal structure has been destroyed.

[0044] Figure 5 It shows that the prepared selective recovery device can efficiently recover lithium ions in waste lithium batteries, wherein the lithium ion recovery rate is about 93.3% and the lithium ion selectivity is about 99.8%.

[0045] Figure 6 It shows that the selective recovery device can efficiently recover lithium ions from waste lithium batteries. During the electrochemical recovery process, the Faraday efficiency is about 96.7%.

[0046] Figure 7 It shows: the reaction principle and process of the prepared selective recovery device.

Claims

1. A hydrophobic selective permeable membrane for simultaneously capturing CO2 and recovering lithium ions in lithium batteries, characterized in that: It includes a cobalt-based two-dimensional conductive metal organic framework hydrophobic support layer and an ionic liquid polyamide lithium ion selection layer.

2. A method for preparing a hydrophobic selective permeable membrane for simultaneously capturing CO2 and recovering lithium ions in lithium batteries as claimed in claim 1, characterized in that: The following steps are involved: Step (1) mixing HAB and Co(II) salt in water to allow them to undergo a complex reaction, slowly adding NH3·H2O solution to the mixed solution and continuously stirring and dissolving until a dark blue precipitate of Co-HAB is generated, centrifuging to remove the supernatant and drying for 10 hours to obtain a cobalt-based two-dimensional conductive metal organic framework; Step (2) adding polytetrafluoroethylene-hexafluoropropylene (PVDF-co-HFP), the cobalt-based two-dimensional conductive metal organic framework obtained in step 1 and acetone to N,N-dimethylformamide, dissolving by magnetic stirring to obtain a spinning solution, and electrospinning to obtain a cobalt-based two-dimensional conductive metal organic framework hydrophobic support layer; Step (3) interfacially polymerizes a selective membrane on the basis of the cobalt-based two-dimensional conductive metal organic framework hydrophobic support layer obtained in step (2), using polyethyleneimine (PEI) as an amine monomer, dissolving piperazine (PIP) and PEI in the ionic liquid [C2mim]BF4, placing the mixed solution on the cobalt-based two-dimensional conductive metal organic framework hydrophobic support layer in step (2) after ultrasonic treatment, leaving it naturally, removing the remaining solution, and drying it to obtain an ionic liquid diamine layer, dissolving TMC in n-hexane, placing the mixed solution on the ionic liquid diamine layer to react and air-dry it, and then placing it in an oven to solidify, to obtain an 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 a hydrophobic selective permeable membrane for simultaneously capturing CO2 and recovering lithium ions in lithium batteries is completed.

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

1.

4. The method for preparing a hydrophobic selective permeable membrane for simultaneously capturing CO2 and recovering lithium ions in lithium batteries according to claim 2, characterized in that: In the step (2), the mass ratio of PVDF-co-HFP to DMF is (3-7):16, the mass ratio of Co-HAB to DMF in step 1 is (5-8):16, and the mass ratio of acetone to DMF is 1:(3-5).

5. The method for preparing a hydrophobic selective permeable membrane for simultaneously capturing CO2 and recovering lithium ions in lithium batteries according to claim 2, characterized in that: In the step (3), the mass ratio of PIP, PEI and ionic liquid [C2mim]BF4 is (0.5-2): (0.5-2): 75, the placement time is 5-20 minutes, the mass concentration of the n-hexane solution of TMC is 0.05-0.5wt%; the reaction time of the mixed solution and the ionic liquid biamine layer in step (3) is 40-80 seconds.

6. A device for simultaneously capturing CO2 and recovering lithium ions in lithium batteries, characterized in that: It comprises the hydrophobic selective permeable membrane for simultaneously capturing CO2 and recovering lithium ions in a lithium battery as described in claim 1, a working electrode, an electrolyte and an external power supply.

7. An application method of the device for simultaneously capturing CO2 and recovering lithium ions in lithium batteries as claimed in claim 6, characterized in that: The following steps are involved: Step (1) Lithium hydroxide electrolyte is placed in a PVDF hollow mold wrapped with a hydrophobic selective permeable membrane for simultaneously capturing CO2 and recovering lithium ions in a lithium battery, and a NCM523 ternary lithium battery is wound between the negative electrode membrane and the positive electrode; Step (2) uses a Cu-Pt electrode as a working electrode, connects to an external power source, and fully enriches the metallic lithium in the waste NCM523 ternary lithium battery into the electrolyte through a rotating table; The device of step (3) continuously passes CO2 gas into lithium hydroxide electrolyte, uses alkaline electrolyte to capture CO2, and generates Li2CO3 precipitate, which is used to simultaneously capture CO2 and promote the efficient recovery of lithium ions in the positive electrode of waste lithium batteries.

8. The method for applying the device for simultaneously capturing CO2 and recovering lithium ions in lithium batteries as claimed in claim 7, characterized in that: In the step (1), the concentration of the lithium hydroxide electrolyte is 50 to 80 mmol / L.

9. The method for applying the device for simultaneously capturing CO2 and recovering lithium ions in lithium batteries as claimed in claim 7, characterized in that: In the step (2), the Pt electrode is inserted into the lithium hydroxide electrolyte, and the voltage of the external power supply is maintained above 3.5V.

10. The method for applying the device for simultaneously capturing CO2 and recovering lithium ions in lithium batteries as claimed in claim 7, characterized in that: In the step (3), the CO2 concentration is above 1000 mg / L, and it can be observed that the electrolyte changes from turbid to producing white precipitate.

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