Method for recovering polymer from separator

Abstract

The present application belongs to the field of batteries. The present application proposes a method for recovering a polymer from a diaphragm, the method comprising: crushing the diaphragm and mixing it with an organic solvent, ultrasonically treating it to obtain a suspension; mixing a surfactant with deionized water to obtain a mixed solution, wherein the molar concentration of the surfactant in the mixed solution is 1mmol / L-10mmol / L, and the surfactant includes at least one of sodium lauryl sulfate, sodium dodecylbenzene sulfonate, and alkyl polyoxypropylene ether sodium sulfate; mixing the suspension and the mixed solution, stirring, filtering, collecting the filter residue and drying it to obtain a polymer. Ceramic particles are solubilized in deionized water by a surfactant to achieve separation of ceramic particles and polymer-based membrane, thereby efficiently recovering the polymer-based membrane. The method is simple, low in cost, and the recovery process is free of secondary pollution, making it easy to industrialize.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and in particular to a method for recovering polymers from separators. Background Art

[0002] As a new type of energy storage device, lithium-ion batteries have been widely used in many fields such as mobile phones, laptops, and digital cameras. With the large-scale scrapping of lithium-ion batteries, how to recycle the polymers in the separator materials of waste lithium-ion batteries has become an urgent problem to be solved.

[0003] Currently, the primary disposal methods for spent lithium-ion battery separator materials are landfill or incineration, which not only results in significant resource waste but also causes severe environmental pollution. While some methods have attempted to recycle separator materials, these methods suffer from numerous drawbacks, including complex processes, high costs, and significant secondary pollution. Therefore, there is an urgent need to develop a simple, efficient, low-cost, and secondary pollution-free method for recovering polymers from spent lithium-ion battery coated separators, thereby realizing resource utilization of solid waste. Summary of the Invention

[0004] The present application aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] The first aspect of the present application provides a method for recovering a polymer from a diaphragm, the method comprising: crushing the diaphragm and mixing it with an organic solvent, and ultrasonically treating it to obtain a suspension; mixing a surfactant with deionized water to obtain a mixed solution, wherein the molar concentration of the surfactant in the mixed solution is 1 mmol / L-10 mmol / L, and the surfactant includes at least one of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium alkyl polyoxypropylene ether sulfate; mixing the suspension and the mixed solution, stirring, filtering, collecting the filter residue and drying it to obtain a polymer.

[0006] The method for recovering polymers from diaphragms proposed in this application uses surfactants to solubilize ceramic particles in deionized water to achieve separation of ceramic particles and polymer-based membranes, thereby efficiently recovering the polymer-based membranes. The method is simple, low-cost, and there is no secondary pollution in the recovery process, making it easy to industrialize.

[0007] According to some embodiments of the present application, the surfactant includes C n H 2n+1 O(CH2OCHCH3) p SO3Na, wherein n is an integer of 8 to 16 and p is an integer of 3 to 12. Thus, the solubilization effect on ceramic particles is improved.

[0008] According to some embodiments of the present application, the molar concentration of the surfactant in the mixed solution is 3 mmol / L-8 mmol / L, thereby improving the solubilization effect on the ceramic particles.

[0009] According to some embodiments of the present application, the power of the ultrasonic treatment is 500W-1000W, and the frequency of the ultrasonic treatment is 100kHz-300kHz, thereby improving the dissolution effect of the binder in the organic solvent.

[0010] According to some embodiments of the present application, the area of ​​the single piece of the diaphragm after being broken is 0.5 cm 2 -10cm 2 Thus, the contact area between the separator and the organic solvent is increased, and the dissolution effect of the binder in the organic solvent is improved.

[0011] According to some embodiments of the present application, the organic solvent includes at least one of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylamide, dimethyl sulfoxide, tetrahydrofuran, and acetone.

[0012] According to some embodiments of the present application, the mass ratio of the membrane to the organic solvent in the suspension is 1:(5-10), thereby fully dissolving the polymer in the membrane.

[0013] According to some embodiments of the present application, when the suspension and the mixed liquid are mixed, the volume ratio of the suspension and the mixed liquid is 1:(0.7-1.3).

[0014] According to some embodiments of the present application, the drying temperature is 80° C.-150° C. Thus, the residual organic solvent in the polymer is reduced.

[0015] According to some embodiments of the present application, the diaphragm includes any one of a polyethylene diaphragm, a polypropylene diaphragm, a polyethylene-polypropylene double-layer diaphragm, and a polyethylene-polypropylene-polyethylene three-layer diaphragm. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0017] Figure 1 A schematic flow chart showing a method for recovering a polymer from a membrane according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0018] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this area or according to the product specifications. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0019] The first aspect of the present application provides a method for recovering a polymer from a diaphragm, the method comprising: disassembling a battery to obtain a diaphragm, crushing the diaphragm and mixing it with an organic solvent, and ultrasonically treating it to obtain a suspension; mixing a surfactant with deionized water to obtain a mixed solution, wherein the molar concentration of the surfactant in the mixed solution is 1 mmol / L-10 mmol / L, and the surfactant includes at least one of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium alkyl polyoxypropylene ether sulfate; mixing the suspension and the mixed solution, stirring, filtering, collecting the filter residue and drying it to obtain a polymer.

[0020] The diaphragm includes a polymer base film and a functional coating located on at least one side of the polymer base film, and the functional coating mainly includes a binder and ceramic particles. The method for recovering polymer from the diaphragm proposed in the present application is to mix the broken diaphragm with an organic solvent, and the organic solvent can dissolve the binder in the functional layer, so that the ceramic particles in the functional layer are separated from the polymer base film. After adding an aqueous solution containing a surfactant, the surfactant is adsorbed on the surface of the ceramic particles by electrostatic action to form a double-layer adsorption micelle, which shows surface solubilization or adsorption solubilization characteristics to the ceramic particles, so that the ceramic particles are solubilized in deionized water. The two-way solvent of organic solvent and deionized water can further enhance this separation effect. The solvent and the ceramic particles in the solvent are removed by filtration, and the filter residue is collected. The composition of the filter residue is the polymer base film, and the residual organic solvent is removed by drying to efficiently recover the polymer base film. The method proposed in the present application is simple in process, easy to operate, does not require complex equipment and processes, and is easy to industrialize. The surfactant used is low in cost, which reduces the recovery cost, and there is no secondary pollution in the recovery process.

[0021] The method proposed in this application is described in detail below. Figure 1 , the method comprising:

[0022] S10: disassembling the battery to obtain a separator, crushing the separator and mixing it with an organic solvent, and ultrasonically treating the separator to obtain a suspension.

[0023] In this step, the separator is obtained by disassembling the battery and then broken down by mechanical crushing or freeze-crushing. The broken fragments are then screened, mixed with an organic solvent, heated and stirred, and ultrasonically dispersed to obtain a suspension. The heating, stirring, and ultrasonic treatment fully dissolve the binder in the functional layer, allowing the ceramic particles to fall out of the separator into the solvent.

[0024] According to some embodiments of the present application, the power of the ultrasonic treatment is 500W-1000W, and the frequency of the ultrasonic treatment is 100kHz-300kHz, thereby improving the dissolution effect of the binder in the organic solvent and fully separating the ceramic particles from the polymer base film.

[0025] As an example, the power of the ultrasonic treatment can be 500W, 600W, 700W, 800W, 900W, 1000W, etc., or can be a range consisting of any of the above values.

[0026] As an example, the frequency of the ultrasonic treatment can be 100 kHz, 150 kHz, 200 kHz, 250 kHz, 300 kHz, etc., or can be a range consisting of any of the above values.

[0027] According to some embodiments of the present application, the area of ​​the single piece of the diaphragm after being broken is 0.5 cm 2 -10cm 2 For example, it can be 0.5cm 2 , 1cm 2 , 3cm 2 , 5cm 2 , 7cm 2 , 9cm 2 , 10cm 2 By breaking the larger diaphragm into smaller diaphragm fragments, the diaphragm fragments are fully contacted with the organic solvent, thereby improving the wetting effect of the organic solvent on the diaphragm fragments and fully dissolving the binder in the functional layer of the diaphragm fragments.

[0028] According to some embodiments of the present application, the organic solvent includes at least one of N-methylpyrrolidone (NMP), N,N-dimethylacetamide, N,N-dimethylamide, dimethyl sulfoxide, tetrahydrofuran, and acetone.

[0029] According to some embodiments of the present application, the organic solvent includes at least one of N-methylpyrrolidone, tetrahydrofuran, and acetone.

[0030] According to some embodiments of the present application, the mass ratio of the separator to the organic solvent in the suspension can be 1:(5-10). For example, the mass ratio can be 1:5, 1:7, 1:9, 1:10, etc., or any range thereof. This allows the binder in the separator functional layer to be fully dissolved.

[0031] S20: mixing a surfactant with deionized water to obtain a mixed solution, wherein the molar concentration of the surfactant in the mixed solution is 1 mmol / L-10 mmol / L, and the surfactant includes at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium alkyl polyoxypropylene ether sulfate.

[0032] In this step, the surfactant is mixed with deionized water. The molar concentration of the surfactant can be 1mmol / L, 3mmol / L, 5mmol / L, 7mmol / L, 9mmol / L, 10mmol / L, etc., or can be a range consisting of any of the above values. Thus, by making the concentration of the surfactant within the above range, the solubilization effect on the ceramic particles is improved. According to some embodiments of the present application, the molar concentration of the surfactant can be 3mmol / L-8mmol / L.

[0033] According to some embodiments of the present application, the surfactant may include C n H 2n+1 O(CH2OCHCH3) p SO3Na, wherein n is an integer from 8 to 16, and p is an integer from 3 to 12.

[0034] Linking group in surfactants - (CH2OCHCH3) p - It has a biphasic affinity, which can increase the adsorption area of ​​surfactants on the surface of ceramic particles and form a double adsorption layer on the surface of ceramic particles, thereby having a stronger adsorption and solubilization ability, making the separation of ceramic particles and polymer-based membranes more thorough, thereby improving the recovery rate of polymer-based membranes.

[0035] As an example, n may be 8, 10, 12, 14, 16, etc., or may be a range consisting of any of the above values.

[0036] As an example, p can be 3, 5, 7, 9, 11, 12, etc., or can be a range consisting of any of the above values.

[0037] According to some embodiments of the present application, the surfactant may be C8H 17 O-(CH2CHCH3O)6SO3Na、C 10 H 21 One or two of O-(CH2CHCH3O)8SO3Na.

[0038] S30: mixing the suspension and the mixed solution, stirring, filtering, collecting the filter residue and drying it to obtain a polymer

[0039] In this step, after the suspension and the mixed liquid are mixed, stirring is continued for 3h-6h, and the mixed liquid is filtered by ultrasonic vibration, the sieve is 200 mesh, and the collected filter residue is rinsed with deionized water. The filter residue is placed under vacuum conditions and dried to obtain a polymer base film.

[0040] According to some embodiments of the present application, when the suspension and the mixed solution are mixed, the volume ratio of the suspension and the mixed solution is 1:(0.7-1.3). Thus, the ceramic particles are solubilized in the deionized water, thereby improving the recovery rate of the polymer-based membrane.

[0041] According to some embodiments of the present application, the volume ratio of the suspension to the mixed liquid is 1:1.

[0042] According to some embodiments of the present application, the drying temperature is 80° C. to 150° C. For example, it can be 80° C., 100° C., 130° C., 150° C., or any range thereof. This reduces the residual organic solvent in the polymer-based film.

[0043] According to some embodiments of the present application, the vacuum degree of the vacuum device is -0.080 MPa (G) to -0.090 MPa (G).

[0044] According to some embodiments of the present application, the drying time is 3 hours to 7 hours.

[0045] According to some embodiments of the present application, the diaphragm includes any one of a polyethylene diaphragm, a polypropylene diaphragm, a polyethylene-polypropylene double-layer diaphragm, and a polyethylene-polypropylene-polyethylene three-layer diaphragm.

[0046] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this area or according to the product specifications. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0047] Example 1

[0048] 1. Use mechanical crushing to crush the waste lithium-ion battery coated diaphragm, screen the broken diaphragm fragments, and control the single piece area to 1cm 2 ~5cm 2 ;

[0049] 2. The membrane fragments (100 g) were mixed with N-methylpyrrolidone (800 g) to obtain a suspension, which was stirred at 100 °C for 5 h while using ultrasonic assisted dispersion with an ultrasonic power of 800 W and an ultrasonic frequency of 200 kHz.

[0050] 3. Add sodium alkyl polyoxypropylene ether sulfate surfactant to deionized water to obtain a mixed solution, C8H 17 O-(CH2CHCH3O)6SO3Na (n=8, p=6), the concentration is controlled at 5mmol / L, the volume ratio of deionized water to organic solvent is 1:1, and stirring is continued for 5h. The material is then filtered by ultrasonic vibration, the screen is 200 mesh, and the filter residue is collected after rinsing three times with deionized water; the filter residue is placed in a vacuum environment with a vacuum degree of -0.080~-0.090MPa and dried at 120°C for 5h to obtain a polymer base film recycled material weighing 85.3g.

[0051] To calculate the recovery rate, the filtrate was concentrated by evaporation to collect the solid residue, which was then washed three times with deionized water to remove the surfactant added in step 3. The solid residue was calcined at 1000°C for 5 h in an air atmosphere to remove organic residues. After calcination, pure ceramic powder weighing 11.6 g was obtained.

[0052] The calculated recovery efficiency is 85.3 / (100-11.6) *100%= 96.5%.

[0053] Example 2

[0054] The method for recovering the polymer-based film from the diaphragm is the same as that in Example 1, except that the organic solvent is tetrahydrofuran.

[0055] Example 3

[0056] The method for recovering the polymer base film from the diaphragm is the same as that in Example 1, except that the surfactant is C 10 H 21 O-(CH2CHCH3O)8SO3Na (n=10, p=8).

[0057] Example 4

[0058] The method for recovering the polymer-based film from the diaphragm is the same as that in Example 1, except that the concentration of the surfactant in the mixed solution is 3 mmol / L.

[0059] Example 5

[0060] The method for recovering the polymer-based film from the diaphragm is the same as that in Example 1, except that the concentration of the surfactant in the mixed solution is 8 mmol / L.

[0061] Example 6

[0062] The method for recovering the polymer-based film from the diaphragm is the same as that in Example 1, except that the concentration of the surfactant in the mixed solution is 1 mmol / L.

[0063] Example 7

[0064] The method for recovering the polymer-based film from the diaphragm is the same as that in Example 1, except that the concentration of the surfactant in the mixed solution is 10 mmol / L.

[0065] Example 8

[0066] The method for recovering the polymer-based film from the diaphragm is the same as that in Example 1, except that the surfactant is sodium lauryl sulfate.

[0067] Example 9

[0068] The method for recovering the polymer-based film from the diaphragm is the same as that in Example 1, except that the surfactant is sodium dodecylbenzenesulfonate.

[0069] Comparative Example 1

[0070] The method for recovering the polymer base film from the diaphragm is the same as that in Example 1, except that:

[0071] 3. Mix deionized water with the suspension, with a volume ratio of deionized water to organic solvent of 1:1, continue stirring for 5 hours, and then filter the material by ultrasonic vibration. The sieve is 200 mesh, and the filter residue is collected after rinsing three times with deionized water; the filter residue is placed in a vacuum environment with a vacuum degree of -0.080~-0.090MPa and dried at 120°C for 5 hours to obtain a polymer base film recycled material.

[0072] Comparative Example 2

[0073] 1. Use mechanical crushing to crush the waste lithium-ion battery coated diaphragm, screen the broken diaphragm fragments, and control the single piece area to 1cm 2 ~5cm 2 ;

[0074] 2. The diaphragm fragments (100 g) were mixed with N-methylpyrrolidone (800 g) to obtain a suspension, which was stirred at 100°C for 5 h. Ultrasonic dispersion was used at a power of 800 W and a frequency of 200 kHz. The material was then filtered using ultrasonic vibration with a 200-mesh screen. The residue was rinsed three times with deionized water and collected. The residue was placed in a vacuum environment with a vacuum degree of -0.080 to -0.090 MPa and dried at 120°C for 5 h to obtain a polymer-based membrane recycled material.

[0075] Comparative Example 3

[0076] The method for recovering the polymer-based film from the diaphragm is the same as that in Example 1, except that the surfactant is cetyltrimethylammonium bromide.

[0077] Comparative Example 4

[0078] The method for recovering the polymer-based film from the diaphragm is the same as that in Example 1, except that the concentration of the surfactant in the mixed solution is 12 mmol / L.

[0079] The recovery rates of the polymers in Examples 1 to 9 and Comparative Examples 1 to 4 are shown in Table 1.

[0080] Table 1

[0081]

[0082] It can be seen from the comparison between Examples 1 to 9 and Comparative Examples 1 to 4 that, in the process of recovering the polymer-based membrane in the diaphragm, by adding a specific type and a specific content of surfactant, the ceramic particles in the diaphragm have a solubilizing function, so that the ceramic particles are completely separated from the polymer-based membrane, and the polymer-based membrane is efficiently recovered.

[0083] Comparing Examples 4-7 with Comparative Example 4 reveals that if the surfactant concentration is too high, the surfactant in the solution is more likely to aggregate into micelles, reducing the number of free surfactant molecules and resulting in a decrease in the amount of surfactant adsorbed on the ceramic particle surface, thus impairing dispersion. Furthermore, excessively high surfactant concentrations increase solution viscosity, reducing the separation efficiency of mechanical agitation, and thus impairing separation results and lowering the recovery rate of the polymer-based membrane.

[0084] From the comparison between Examples 1 to 9 and Comparative Example 3, it can be seen that the use of anionic surfactants has a better solubilization effect on ceramic particles and can improve the recovery rate of the polymer-based membrane.

[0085] It can be seen from the comparison of Examples 1 to 9 with Comparative Examples 1 and 2 that using only deionized water to clean the suspension containing the diaphragm fragments cannot completely wash away the ceramic particles in the diaphragm, and the recovery rate of the polymer-based membrane is low.

[0086] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0087] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for recovering a polymer from a diaphragm, characterized in that: include: The membrane is crushed and mixed with an organic solvent, and ultrasonicated to obtain a suspension; Mixing a surfactant with deionized water to obtain a mixed solution, wherein the molar concentration of the surfactant in the mixed solution is 1 mmol / L-10 mmol / L, and the surfactant includes at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium alkyl polyoxypropylene ether sulfate; The suspension and the mixed liquid are mixed, stirred, filtered, and the filter residue is collected and dried to obtain a polymer, wherein the mass ratio of the diaphragm to the organic solvent in the suspension is 1:(5-10), and when the suspension and the mixed liquid are mixed, the volume ratio of the suspension to the mixed liquid is 1:(0.7-1.3).

2. The method according to claim 1, characterized in that The surfactant includes C n H 2n+1 O(CH2OCHCH3) p SO3Na, wherein n is an integer from 8 to 16, and p is an integer from 3 to 12.

3. The method according to claim 1 or 2, characterized in that The molar concentration of the surfactant in the mixed solution is 3 mmol / L-8 mmol / L.

4. The method according to claim 1 or 2, characterized in that The power of the ultrasonic treatment is 500W-1000W, and the frequency of the ultrasonic treatment is 100kHz-300kHz.

5. The method according to claim 1 or 2, characterized in that The area of ​​the single piece of the diaphragm after breaking is 0.5cm 2 -10cm 2 .

6. The method according to claim 1 or 2, characterized in that The organic solvent includes at least one of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylamide, dimethyl sulfoxide, tetrahydrofuran, and acetone.

7. The method according to claim 1 or 2, characterized in that The drying temperature is 80°C-150°C.

8. The method according to claim 1 or 2, characterized in that The diaphragm includes any one of a polyethylene diaphragm, a polypropylene diaphragm, a polyethylene-polypropylene double-layer diaphragm, and a polyethylene-polypropylene-polyethylene three-layer diaphragm.

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