Covalent organic framework ion separation membrane as well as preparation method and application thereof

Abstract

The invention provides a covalent organic framework ion separation membrane as well as a preparation method and application thereof, and belongs to the technical field of recycling of waste lithium ion batteries. The covalent organic framework ion separation membrane material is simple to prepare, can be produced on a large scale, has stable performance, and is obviously different from a conventional commercial graphene oxide ion separation membrane or other complex ion separation membrane materials. According to the ion separation membrane material prepared by the invention, after N sites in pyridine diamine are doped into the covalent organic framework, cobalt and nickel ions in an electrode leaching solution can be anchored, and the transmembrane transmission behavior of the cobalt and nickel ions is hindered, so that the selectivity and permeability of the ion separation membrane are remarkably improved. The preparation process is safe and simple, the raw materials are cheap and easy to obtain, the preparation cost is low, and large-scale preparation is easy to realize.

Description

Technical Field

[0001] The present application relates to the technical field of recycling waste lithium-ion batteries, and in particular to a covalent organic framework ion separation membrane and a preparation method and application thereof. Background Art

[0002] The new energy vehicle industry is developing rapidly. Among them, the demand for lithium-ion batteries (LIB), as the core components of pure electric vehicles and hybrid vehicles, has increased significantly. With the increase in the installed capacity of power batteries and the rise of the battery recycling industry, the number of retired power batteries will increase. Therefore, recycling and reusing the components of retired lithium-ion batteries is not only a necessary measure to solve environmental problems, but also an important means of recycling upstream resources.

[0003] The comprehensive utilization of waste power batteries from new energy vehicles includes cascade utilization and recycling. Since the current cascade utilization technology is not yet mature, recycling is generally used to dismantle and recycle retired lithium-ion batteries.

[0004] The current recycling technologies for retired lithium-ion batteries mainly include two traditional methods: pyrometallurgical recycling and wet recycling.

[0005] Pyrometallurgical recycling refers to the direct recycling of various battery materials or metals without the use of solutions or other media, mainly including mechanical sorting and high-temperature electrolysis. The core process of pyrometallurgy is high-temperature pyrolysis to obtain metal oxides. The advantage is that the process is simple and can recycle more heavy metals such as mercury, nickel, and zinc; the disadvantage is that the yield is low, the energy consumption is high, and it will produce certain waste pollution.

[0006] Wet recycling is to disassemble and pre-treat waste batteries and dissolve them in acid-base solutions to extract some valuable metal elements, and then extract the remaining valuable metals through ion exchange and electrodeposition. The core process of the wet method is to add chemical reagents to the electrode powder for leaching and extraction. The advantages are low equipment and operation requirements, multiple chemical reaction options, high product purity, and high efficiency in recycling heavy metal substances in batteries. The disadvantages are long process flow, corrosive solvents involved in the recycling process, and problems such as waste liquid pollution.

[0007] From the comparison of current recycling technology routes, wet recycling has a high recovery rate for metal elements and high purity of the prepared products, and has become the mainstream technology route in the industry. However, the chemical reagents and energy costs used are high, and there are many processes and steps, which makes it difficult to achieve green and sustainable recovery of valuable metal resources. Membrane separation technology meets these requirements very well. The membrane separation process is an efficient and environmentally friendly separation process, and is a high-tech cross-disciplinary technology.

[0008] Since the hydration diameter of lithium ions in the leachate is different from that of cobalt ions, nickel ions and other valuable metal ions, It is difficult for traditional separation membranes to selectively separate them directly by pore size. Here, according to the guidance of the "soft and hard acid-base theory", a two-dimensional covalent organic framework separation membrane is constructed by introducing pyridine functional groups, and the pyridine group is used to interact with the boundary base and boundary acid of cobalt and nickel ions, and the cobalt and nickel ions are anchored at the pyridine N site to hinder their transmembrane transmission behavior, thereby realizing the specific transmission of lithium ions and achieving the purpose of recycling waste lithium-ion battery positive electrode materials. The above separation membrane material has the advantages of environmental friendliness, low energy consumption, strong continuity, and high selectivity. It is a very promising ion screening membrane material. Summary of the invention

[0009] Technical problems to be solved: In view of the technical problems in the prior art such as low pyrometallurgical recovery yield, high energy consumption, certain waste pollution, long wet recovery process, corrosive solvents involved in the recovery process, waste liquid pollution, etc., a covalent organic framework ion separation membrane and its preparation method and application are provided. The separation membrane can separate and recover lithium, cobalt and nickel resources in the positive electrode leachate of waste lithium-ion batteries at room temperature and pressure. It not only has lithium ion selectivity significantly higher than that of ordinary commercial separation membranes, but also has a large flux.

[0010] A method for preparing a covalent organic framework ion separation membrane, the preparation method comprising the following steps:

[0011] Step 1: dissolving trialdehyde phloroglucinol in dichloromethane as solution A;

[0012] Step 2: dissolving 2,5-diaminopyridine and p-toluenesulfonic acid monohydrate in water and ultrasonically dispersing the solution as solution B;

[0013] Step 3: Place the commercial polyacrylonitrile membrane at the connection of the H-type electrolytic cell and fix it;

[0014] Step 4: adding solution A and solution B into two chambers of an H-type electrolytic cell equipped with a commercial polyacrylonitrile membrane, wherein solution A is placed in the chamber facing the front side of the polyacrylonitrile membrane, and solution B is placed in the chamber facing the back side;

[0015] Step 5: After standing for reaction at room temperature and normal pressure, the covalent organic framework ion separation membrane is obtained.

[0016] Furthermore, the molar ratio of trialdehyde phloroglucinol to 2,5-diaminopyridine is 2:3.

[0017] Furthermore, in the first step, 30 mL of dichloromethane is used.

[0018] Furthermore, in the second step, the molar ratio of 2,5-diaminopyridine to p-toluenesulfonic acid monohydrate is 1:2, the ultrasonic dispersion time is 0.5 to 1 hour, and the water is 10 mL of deionized water.

[0019] Furthermore, in the third step, the inner diameter of the H-type electrolytic cell is 1.5 cm.

[0020] Furthermore, in the fourth step, 20 mL of deionized water is added into the H-type electrolytic cell chamber facing the back side of the polyacrylonitrile membrane, and then the solution B is added drop by drop into the chamber facing the back side of the polyacrylonitrile membrane.

[0021] Furthermore, in the fifth step, after the upper end of the H-type electrolytic cell is sealed, the reaction temperature of the static reaction is room temperature, and the reaction time is 72 to 80 hours.

[0022] The present application also discloses a covalent organic framework ion separation membrane, which is composed of an active component and a self-supporting substrate. The active component is a covalent organic framework, the thickness of the covalent organic framework layer is 3.3-3.5 μm, the covalent organic framework is COF-TpPy prepared by interfacial polymerization, the synthesis components of the covalent organic framework are trialdehyde pyrrolidine and 2,5-diaminopyridine, and the component of the self-supporting substrate is polyacrylonitrile PAN or polystyrene.

[0023] Furthermore, the COF-TpPy has a two-dimensional framework composed of pyridine diamine with pyridine sites as components.

[0024] The present application also discloses the use of a covalent organic framework ion separation membrane in extracting lithium ions from covalent old lithium ion batteries. The covalent organic framework ion separation membrane screens valuable metal ions through a covalent organic framework. The covalent old lithium ion batteries are waste lithium ion batteries, and lithium ions are extracted from the leachate of the waste lithium ion batteries.

[0025] Principle explanation: According to the hard-soft acid-base theory (i.e., hard acids and hard bases will have strong interactions, boundary acids and boundary bases will have strong interactions, and soft acids and soft bases will have strong interactions), by introducing abundant pyridine sites into the covalent organic framework as a reactive monomer, the pyridine sites as boundary bases can have strong interactions with cobalt ions and nickel ions as boundary acids, increasing the transmembrane transport resistance of cobalt ions and nickel ions, thereby hindering the transmembrane transport behavior of cobalt ions and nickel ions. Lithium ions and manganese ions, as hard acids, will not have strong interactions with pyridine sites, but manganese ions have a larger hydration diameter and carry more positive charges, making them more easily attracted to pyridine sites than lithium ions, making it more difficult to successfully complete transmembrane transport behavior, thereby obtaining superior monovalent / divalent ion selectivity.

[0026] Beneficial effects:

[0027] 1. The pores of COF-TpPy have abundant pyridine sites, which have excellent lithium ion selectivity and permeability to valuable metals and excellent separation performance;

[0028] 2. Polyacrylonitrile has high hydrophilicity, which increases the mechanical properties of the composite membrane and its tolerance in aqueous solution;

[0029] 3. Compared with conventional graphene oxide separation membranes, the covalent organic framework ion separation composite membrane provided by the present application has good stability in aqueous solution, can be used in aqueous solution for a long time, and has good mechanical properties;

[0030] 4. Compared with conventional commercial polymer separation membranes, the covalent organic framework ion separation composite membrane provided by the present application has excellent monovalent / divalent ion selectivity and can separate lithium ions in the positive electrode leachate of waste lithium-ion batteries;

[0031] 5. The preparation of the covalent organic framework ion separation composite membrane provided in this application has the advantages of simple and safe preparation process, and is easy to achieve large-scale preparation;

[0032] 6. Compared with the existing ion separation membranes, the two-dimensional covalent organic framework ion separation membrane prepared in this application has higher selectivity (Li + / Co 2+ The selectivity is about 100, Li + / Ni 2+ The selectivity is about 100, Li + / Mn 2+ The selectivity is about 60; the monovalent / divalent ion selectivity of commercial PAN membrane is about 2) and flux, which has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The scanning electron microscope images of the ion separation membrane in Example 1 of the present application, wherein the upper image is a surface scanning electron microscope image of the COF-TpPa membrane, and the lower image is a cross-sectional scanning electron microscope image of the COF-TpPa membrane;

[0034] Figure 2 The X-ray diffraction analysis spectra of the ion separation membrane in Example 1 and Comparative Example 1 of the present application, wherein the left figure is the X-ray diffraction analysis spectrum of the ion separation membrane in Example 1, and the right figure is the X-ray diffraction analysis spectrum of the ion separation membrane in Comparative Example 1;

[0035] Figure 3 The figure is a graph showing the test results of the osmotic diffusion method of a single solution under the reaction conditions of room temperature and normal pressure of Example 1 and Comparative Example 1 of the present application, wherein the left figure is a graph showing the test results of the osmotic diffusion method of a single solution under the reaction conditions of room temperature and normal pressure in Example 1, and the right figure is a graph showing the test results of the osmotic diffusion method of a single solution under the reaction conditions of room temperature and normal pressure in Comparative Example 1;

[0036] Figure 4This is a graph showing the test results of the osmotic diffusion method of the mixed solution under reaction conditions of room temperature and normal pressure in Example 1 of the present application. DETAILED DESCRIPTION

[0037] The following are only embodiments of the present invention, and are not intended to limit the scope of the present invention. The present invention can be implemented in different forms, and all contents made using the contents of the present invention specification are included in the scope of patent protection of the present invention. The embodiments are provided to make the contents disclosed in the present invention more thorough and comprehensive.

[0038] Unless otherwise specified, all numbers appearing in the specification and claims of this application, such as active components, temperature and time, gas conversion rate, etc., should not be understood as absolutely precise values. Due to the standard deviation of the measurement technology, the measured values ​​inevitably have certain experimental errors.

[0039] Unless otherwise specified, the raw materials and reagents in the examples of this application can be purchased through commercial channels. The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0040] Example 1

[0041] A method for preparing a covalent organic framework ion separation membrane, the preparation method comprising the following steps:

[0042] Step 1: Dissolve 0.2 mmol of trialdehyde phloroglucinol in 30 mL of dichloromethane as solution A;

[0043] Step 2: Dissolve 0.3 mmol 2,5-diaminopyridine and 0.6 mmol p-toluenesulfonic acid monohydrate in water and disperse by ultrasonic for 0.5 to 1 hour as solution B;

[0044] Step 3: Place the commercial polyacrylonitrile membrane at the connection of the H-type electrolytic cell and fix it;

[0045] Step 4: Add solution A and solution B into two chambers of an H-type electrolytic cell equipped with a commercial polyacrylonitrile membrane, where

[0046] Solution A is placed in the chamber facing the front of the polyacrylonitrile membrane, 20 mL of deionized water is added to the chamber of the H-type electrolytic cell facing the back of the polyacrylonitrile membrane, and the above solution B is added dropwise into the deionized water;

[0047] Step 5: Seal the upper end of the H-type electrolytic cell and let it stand at room temperature for 72 to 80 hours. After the reaction, the covalent organic framework ion separation membrane TpPa-Py is obtained.

[0048] Comparative Example 1

[0049] A method for preparing a TpPa separation membrane, the preparation method comprising the following steps:

[0050] Step 1: Dissolve 0.2 mmol of trialdehyde phloroglucinol in 30 mL of dichloromethane as solution C;

[0051] Step 2: Dissolve 0.3 mmol p-phenylenediamine and 0.4 mmol p-toluenesulfonic acid monohydrate in 10 mL water and disperse by ultrasonic for 0.5 to 1 hour to prepare solution D;

[0052] Step 3: Place the commercial polyacrylonitrile membrane at the connection of the H-type electrolytic cell and fix it;

[0053] Step 4: Add solution C and solution D into two chambers of an H-type electrolytic cell equipped with a commercial polyacrylonitrile membrane, where

[0054] Solution C is placed in the chamber facing the front of the polyacrylonitrile membrane, 20 mL of deionized water is added to the chamber of the H-type electrolytic cell facing the back of the polyacrylonitrile membrane, and the above solution D is added dropwise into the deionized water;

[0055] Step 5: After sealing the upper end of the H-type electrolytic cell, let it stand at room temperature for 72 to 80 hours. After standing and reacting, the separation membrane TpPa of Comparative Example 1 is obtained.

[0056] Figure 2 It is the X-ray diffraction analysis spectrum of the ion separation membrane in Example 1 and Comparative Example 1 of the present application, wherein the left figure is the X-ray diffraction analysis spectrum of the ion separation membrane in Example 1, and the right figure is the X-ray diffraction analysis spectrum of the ion separation membrane in Comparative Example 1, indicating that the two-dimensional covalent organic framework material was successfully grown in situ on the commercial polyacrylonitrile membrane substrate by interfacial polymerization.

[0057] Figure 3 It is a graph showing the test results of the osmotic diffusion method of a single solution under the reaction conditions of room temperature and normal pressure of Example 1 and Comparative Example 1 of the present application, wherein the left graph is a graph showing the test results of the osmotic diffusion method of a single solution under the reaction conditions of room temperature and normal pressure in Example 1, and the right graph is a graph showing the test results of the osmotic diffusion method of a single solution under the reaction conditions of room temperature and normal pressure in Comparative Example 1. As shown in the graph, the lithium ion selectivity and flux of Example 1 are significantly better than those of Comparative Example 1.

[0058] Figure 4 This is a graph showing the test results of the osmotic diffusion method of the mixed solution of Example 1 of the present application under reaction conditions of room temperature and normal pressure. When simulating the electrode leaching solution, Example 1 exhibits excellent lithium ion extraction performance.

[0059] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a covalent organic framework ion separation membrane, characterized in that: The preparation method comprises the following steps: Step 1: dissolving trialdehyde phloroglucinol in dichloromethane as solution A; Step 2: dissolving 2,5-diaminopyridine and p-toluenesulfonic acid monohydrate in water and ultrasonically dispersing the solution as solution B; Step 3: Place the commercial polyacrylonitrile membrane at the connection of the H-type electrolytic cell and fix it; Step 4: adding solution A and solution B into two chambers of an H-type electrolytic cell equipped with a commercial polyacrylonitrile membrane, wherein solution A is placed in the chamber facing the front side of the polyacrylonitrile membrane, and solution B is placed in the chamber facing the back side; Step 5: After standing for reaction at room temperature and normal pressure, the covalent organic framework ion separation membrane is obtained.

2. The method for preparing the covalent organic framework ion separation membrane according to claim 1, characterized in that: The molar ratio of trialdehyde phloroglucinol to 2,5-diaminopyridine is 2:

3.

3. The method for preparing the covalent organic framework ion separation membrane according to claim 1, characterized in that: In the first step, 30 mL of dichloromethane was used.

4. The method for preparing the covalent organic framework ion separation membrane according to claim 1, characterized in that: In the second step, the molar ratio of 2,5-diaminopyridine to p-toluenesulfonic acid monohydrate is 1:2, the ultrasonic dispersion time is 0.5 to 1 hour, and the water is 10 mL of deionized water.

5. The method for preparing the covalent organic framework ion separation membrane according to claim 1, characterized in that: In the third step, the inner diameter of the H-type electrolytic cell is 1.5 cm.

6. The method for preparing the covalent organic framework ion separation membrane according to claim 1, characterized in that: In the fourth step, 20 mL of deionized water was added to the H-type electrolytic cell chamber facing the back of the polyacrylonitrile membrane, and then solution B was added drop by drop into the chamber facing the back of the polyacrylonitrile membrane.

7. The method for preparing the covalent organic framework ion separation membrane according to claim 1, characterized in that: In the fifth step, after the upper end of the H-type electrolytic cell is sealed, the reaction temperature is room temperature and the reaction time is 72 to 80 hours.

8. A covalent organic framework ion separation membrane prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The covalent organic framework ion separation membrane consists of an active component and a self-supporting substrate. The active component is a covalent organic framework, the thickness of the covalent organic framework layer is 3.3-3.5 μm, the covalent organic framework is COF-TpPy prepared by an interfacial polymerization method, the synthesis components of the covalent organic framework are trialdehyde phloroglucinol and 2,5-diaminopyridine, and the component of the self-supporting substrate is polyacrylonitrile PAN or polystyrene.

9. A covalent organic framework ion separation membrane according to claim 8, characterized in that: The COF-TpPy has a two-dimensional framework composed of pyridine diamine with pyridine sites as components.

10. Use of the covalent organic framework ion separation membrane according to claim 8 in extracting lithium ions from covalent old lithium ion batteries, characterized in that: The covalent organic framework ion separation membrane screens the valuable metal ions through the covalent organic framework. The covalent old lithium ion battery is a waste lithium ion battery, and lithium ions are extracted from the leachate of the waste lithium ion battery.

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