Lithium ion spraying diaphragm PVDF (Polyvinylidene Fluoride) recovery device and recovery method

Abstract

The invention discloses a lithium ion spraying diaphragm PVDF (Polyvinylidene Fluoride) recovery device which comprises a pretreatment unit, the pretreatment unit is used for carrying out particle treatment on a material, the pretreatment unit is connected with a dissolving unit, the dissolving unit is used for preparing the material into a solution in a heating and stirring manner, the dissolving unit is connected with a filtering unit, the filtering unit is connected with a precipitation unit, and the precipitation unit is connected with a drying unit. A solution filtered by the filtering unit enters the precipitation unit and is matched with a precipitator for solid-liquid separation, and the drying unit is arranged on one side of the precipitation unit and is used for drying precipitated solids in the precipitation unit. According to the lithium ion spraying diaphragm PVDF recovery device, the structure is simple, the operation is convenient, PVDF in the lithium ion spraying diaphragm can be effectively recovered, the resource utilization rate is improved, and the environmental pollution is reduced; the method for recovering the PVDF by using the recovery device has the advantages of simple process and lower cost, the recovered PVDF is high in purity, and the utilization rate and the recovery efficiency of the material are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion battery recycling, and in particular to a lithium ion spraying diaphragm PVDF recycling device and a recycling method. Background Art

[0002] Lithium-ion batteries are secondary batteries, i.e. rechargeable batteries, which mainly rely on the movement of lithium ions between the positive and negative electrodes to work. With the widespread application of lithium-ion batteries in new energy vehicles, energy storage and other fields, the number of waste lithium-ion batteries is also increasing. In lithium-ion batteries, their spray diaphragms usually contain polyvinylidene fluoride (PVDF), which has good chemical stability, thermal stability and mechanical properties, and has a high recycling value.

[0003] At present, the PVDF in lithium-ion spray diaphragms is usually extracted and reused by traditional recycling methods such as physical recycling, chemical recycling, and pyrolysis recycling. However, these traditional recycling methods are not only costly and complicated to operate, but also have poor recycling efficiency and purity. Summary of the invention

[0004] The purpose of the present invention is to solve the problems of the above-mentioned background technology and to propose a lithium ion sprayed diaphragm PVDF recovery device and recovery method.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A lithium ion spray diaphragm PVDF recovery device comprises: a pretreatment unit, the pretreatment unit is used to process the material into particles, the pretreatment unit is connected to a dissolution unit, the dissolution unit is used to configure the material into a solution by heating and stirring, the dissolution unit is connected to a filtration unit, the filtration unit is connected to a precipitation unit, the solution filtered by the filtration unit enters the precipitation unit, and a precipitant is used to separate the solid from the liquid, a drying unit is arranged on one side of the precipitation unit, and the drying unit is used to dry the precipitated solid in the precipitation unit.

[0007] As a further solution of the present invention: the pretreatment unit comprises a feed hopper, a crushing mechanism is arranged in the feed hopper, and a screening mechanism is arranged below the crushing mechanism.

[0008] As a further solution of the present invention: the dissolving unit comprises a reactor, and the feed port of the reactor is connected to the discharge port of the feed hopper.

[0009] As a further solution of the present invention: the reaction kettle is a kettle body with a double-layer hollow structure.

[0010] As a further solution of the present invention: the reactor is provided with a stirring mechanism and a heating mechanism, and the stirring mechanism and the heating mechanism cooperate to accelerate the dissolution of the material.

[0011] As a further solution of the present invention: the precipitation unit comprises a precipitation tank, and a stirring paddle is arranged in the precipitation tank.

[0012] A method for recovering PVDF in a lithium ion sprayed diaphragm PVDF recovery device comprises:

[0013] S1. Put the waste lithium ion spray diaphragm into the feed hopper, crush it by a crushing mechanism, and screen the crushed material into a material of standard particle size by a screening mechanism;

[0014] S2, adding the screened material into a reactor, adding an organic solvent, raising the temperature in the reactor to a preset temperature through a heating mechanism, and stirring the stirring device for a preset time to fully dissolve the PVDF;

[0015] S3, filtering the dissolved solution to remove insoluble impurities;

[0016] S4, transporting the filtered solution to a precipitation tank, adding a precipitant to precipitate PVDF;

[0017] S5. Place the precipitate in a drying oven, adjust the drying temperature and drying time, and obtain a recovered PVDF product.

[0018] As a further solution of the present invention: in the step S1, the standard particle size range is 1 mm-5 mm.

[0019] As a further solution of the present invention: in step S2, the mass ratio of the organic solvent to the material is 5:1.

[0020] As a further solution of the present invention: in step S4, the volume ratio of the precipitant to the solution is 3:1.

[0021] Beneficial effects of the present invention:

[0022] (1) In the present invention, the PVDF recovery device for lithium ion sprayed diaphragm has a simple structure and is easy to operate. It can effectively recover PVDF in the lithium ion sprayed diaphragm, improve resource utilization, and reduce environmental pollution.

[0023] (2) In the present invention, the method for recovering PVDF using the recovery device has the advantages of simple process and low cost. The recovered PVDF has high purity, which significantly improves the utilization rate and recovery efficiency of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] Figure 1 It is a structural schematic diagram of the lithium ion spraying diaphragm PVDF recovery device of the present invention;

[0026] Figure 2 It is a schematic flow diagram of a PVDF recovery method in a lithium ion sprayed diaphragm PVDF recovery device of the present invention.

[0027] In the figure: 1. feed hopper; 11. crushing mechanism; 12. screening mechanism; 2. reaction kettle; 21. stirring mechanism; 22. heating mechanism; 3. filter; 4. sedimentation tank; 41. stirring paddle; 5. drying box. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] See also Figure 1 As shown, the present invention is a lithium ion spray diaphragm PVDF recovery device, including: a pretreatment unit, the pretreatment unit is used to process the material into particles, the pretreatment unit is connected to the dissolution unit, the dissolution unit is used to configure the material into a solution by heating and stirring, the dissolution unit is connected to the filtration unit, the filtration unit uses a filter 3, and the filter 3 includes but is not limited to a pressure filter, a vacuum filter and a centrifugal filter. The filtration unit is connected to the precipitation unit, and the solution filtered by the filtration unit enters the precipitation unit, and the precipitant is used for solid-liquid separation. A drying unit is also set on one side of the precipitation unit, and the drying unit is used to dry the precipitated solid in the precipitation unit.

[0030] Specifically, the pretreatment unit includes a feed hopper 1, and a crushing mechanism 11 is arranged in the feed hopper 1. The crushing mechanism 11 includes but is not limited to an impact crusher, a hammer crusher, a roller crusher, and a shear crusher. Preferably, a hammer crusher and a shear crusher are used. These two crushers can effectively process waste lithium ion spray diaphragms and help crush them into particles for subsequent recycling and treatment.

[0031] Furthermore, a screening mechanism 12 is arranged below the crushing mechanism 11. The screening mechanism 12 includes but is not limited to a vibrating screen, a drum screen, and a circular screen. Preferably, a circular screen is used. The circular screen can realize material classification through rotation and vibration and is often used for screening of finer particles. On the one hand, it can effectively separate particles of required fineness. On the other hand, it can test the crushing effect of the crushing mechanism 11, which is convenient for judging whether the crushing mechanism 11 needs to be replaced and repaired.

[0032] The dissolving unit comprises a reactor 2, the feed port of the reactor 2 is connected with the discharge port of the feed hopper 1 through a pipeline, so that the particles screened by the screening mechanism 12 can smoothly enter the reactor.

[0033] Among them, the reactor 2 is a double-layer hollow structure reactor body, the inner side wall of the reactor body is made of heat-conducting material, including but not limited to ceramic material and alumina material, and the outer side wall of the reactor body is covered with thermal insulation cotton to reduce heat loss.

[0034] A stirring mechanism 21 and a heating mechanism 22 are provided in the reaction kettle 2, and the stirring mechanism 21 and the heating mechanism 22 cooperate to accelerate the dissolution of the material.

[0035] Specifically, the stirring mechanism 21 is a structure in which a stirring rod is driven by a motor to rotate, so as to facilitate uniform mixing of the organic solvent and the material in the reactor 2. A cavity is provided between the double-layer side walls of the reactor 2, and the heating mechanism 22 is located in the cavity. The heating mechanism 22 is a serpentine curved pipe wound around the inner wall of the reactor, and steam or heat transfer oil can be introduced into the curved pipe to increase the temperature in the entire reactor 2, so as to facilitate the dissolution of the material in the reactor.

[0036] It is understandable that the heating mechanism 22 may also adopt an electric heating rod or an electric heating tape, and the heat generated by the heating mechanism 22 may be transferred to the reactor by converting electrical energy into thermal energy.

[0037] The precipitation unit comprises a precipitation tank 4, in which a stirring paddle 41 is arranged. The stirring paddle 41 is a frame-type stirring paddle. The frame-type stirring paddle has a large vertical stirring range, which is convenient for stirring the solution and the precipitant in the precipitation tank 4 evenly, and is beneficial to increasing the precipitation speed of PVDF.

[0038] See also Figure 2 As shown, a method for recovering PVDF in a lithium ion sprayed diaphragm PVDF recovery device comprises:

[0039] S1. Put the waste lithium ion spray diaphragm into the feed hopper 1, crush it through the crushing mechanism 11, and screen the crushed material through the screening mechanism 12 to obtain the material of standard particle size, wherein the standard particle size range is 1mm-5mm.

[0040] S2. Add the screened material into the reactor 2, add an organic solvent, the mass ratio of the organic solvent to the material is 5:1, and raise the temperature in the reactor 3 to a preset temperature of 80°C through the heating mechanism 5. The stirring device mechanism 21 stirs for a preset time. The PVDF can be fully dissolved by heating, and the dissolution time is shortened to 2h, which is the preset dissolution time.

[0041] Specifically, the organic solvent may be NMP or DMF. These two solvents have strong dissolving ability and can effectively dissolve PVDF. NMP and DMF have high polarity and can destroy the interaction between the polymer chains of PVDF, thereby dissolving PVDF and facilitating the subsequent separation and recovery process.

[0042] S3, conveying the dissolved solution to the filter 3 for filtering to remove insoluble impurities in the solution.

[0043] S4, the filtered solution is transported to the precipitation tank 4, and a precipitant is added. The volume ratio of the precipitant to the solution is 3:1. The precipitant causes PVDF to precipitate. The precipitation time is 1 hour.

[0044] The precipitant can be water or ethanol solution. Water or ethanol solution has a low solubility for PVDF. When PVDF is added to water or ethanol from NMP or DMF solution, the polarity of the solvent decreases and the solubility of PVDF decreases, resulting in the precipitation of PVDF. This process utilizes the influence of solvent selectivity to achieve separation and recovery, thereby improving the recovery purity of PVDF.

[0045] S5. Place the precipitate in a drying oven 5, adjust the drying temperature and drying time, and dry the precipitate at 80° C. for 4 hours to obtain a recovered PVDF product.

[0046] After testing, the purity of the PVDF product recovered in this embodiment reached more than 98%, and the experimental data are as follows:

[0047] Take 6 batches of PVDF recovered by this device, 20g each, record as W 总 The recovered PVDF is purified by this method, weighed, and recorded as W PVDF , calculate the purity of PVDF after recovery, the calculation formula is as follows:

[0048]

[0049] The results are shown in Table 1:

[0050] Table 1

[0051] Group <![CDATA[W 总 (g)]]> <![CDATA[W PVDF (g)]]> purity(%) 1 20 19.7 98.5％ 2 20 19.64 98.2％ 3 20 19.62 98.1％ 4 20 19.74 98.7％ 5 20 19.62 98.1％ 6 20 19.66 98.3％

[0052] The inventors have found that traditional recycling methods generally include physical recycling (through physical treatment such as crushing and grading, PVDF waste is separated and refined to obtain powder or granular materials that meet the reprocessing requirements), chemical recycling (using chemical methods such as dissolution, reflux extraction and other technologies to extract and regenerate high-purity PVDF substances from PVDF waste), pyrolysis recycling (through high-temperature pyrolysis of PVDF waste to recover fluorine and other valuable materials therein), subcritical water treatment recycling (mineralization of PVDF under subcritical water conditions to achieve closed-loop fluorine chemical circulation), and biological recycling (using microorganisms to degrade and transform PVDF waste). However, these traditional recycling methods have problems such as low efficiency, high cost, complex operation, and low purity.

[0053] The experimental data of the purity of PVDF products recovered by traditional recovery methods are as follows:

[0054] Physical method: Take 20g of each of the 6 batches of recycled PVDF and record it as W 总 , the recovered PVDF was purified by physical method, weighed, and recorded as W PVDF , calculate the purity of PVDF after recovery, the calculation formula is as follows:

[0055]

[0056] The results are shown in Table 2:

[0057] Table 2 Purity of PVDF recovered by physical method

[0058] Group <![CDATA[W 总 (g)]]> <![CDATA[W PVDF (g)]]> purity(%) 1 20 16.91 84.5％ 2 20 16.42 82.1％ 3 20 17.35 86.7％ 4 20 18.21 91.1％ 5 20 17.47 87.4％ 6 20 17.21 86.0％

[0059] From the data in Table 2, it can be seen that the purity of the six batches of PVDF recovered by the physical method was tested and found to be quite different, and the purity of the recovered PVDF was not stable enough.

[0060] Chemical method: Take 6 batches of recycled PVDF, 20g each, and record it as W 总 The recovered PVDF was purified by chemical method, weighed, and recorded as W PVDF , calculate the purity of PVDF after recovery, the calculation formula is as follows:

[0061]

[0062] The results are shown in Table 3:

[0063] Table 3 Purity of PVDF recovered by chemical method

[0064] Group <![CDATA[W 总 (g)]]> <![CDATA[W PVDF (g)]]> purity(%) 1 20 18.91 94.6％ 2 20 18.2 91％ 3 20 18.31 91.6％ 4 20 18.21 91％ 5 20 18.47 92.3％ 6 20 18.27 91.4％

[0065] It can be seen from the data in Table 3 that the purity of the 6 batches of PVDF recovered by the chemical method was tested and found to be no more than 98%.

[0066] Mixing method: Take 20g of each of 6 batches of recycled PVDF and record it as W 总 , the recovered PVDF was purified by mixing method, weighed, and recorded as W PVDF , calculate the purity of PVDF after recovery, the calculation formula is as follows:

[0067]

[0068] The results are shown in Table 4:

[0069] Table 4 PVDF purity recovered by mixed method

[0070] Group <![CDATA[W 总 (g)]]> <![CDATA[W PVDF (g)]]> purity(%) 1 20 19.1 95.6％ 2 20 19.24 96.2％ 3 20 19.31 96.6％ 4 20 19.34 96.7％ 5 20 19.47 97.4％ 6 20 19.27 96.4％

[0071] It can be seen from the data in Table 4 that the purity of 6 batches of PVDF recovered by the mixing method was tested and found to be no more than 98%.

[0072] The experimental data in Tables 1 to 4 show that the purity of PVDF recovered by the device is higher than that of the traditional recovery method, and the recovery purity is relatively stable.

[0073] In this embodiment, the PVDF recovery device for lithium ion sprayed membrane has a simple structure and is easy to operate. It can effectively recover the PVDF in the lithium ion sprayed membrane, improve resource utilization, and reduce environmental pollution.

[0074] In the present application, the method for recovering PVDF using the recovery device has the advantages of simple process and low cost. The separation and recovery of PVDF is achieved by utilizing the influence of solvent selectivity. The recovered PVDF has high purity. The problem of recycling PVDF in coating materials is effectively solved, which significantly improves the utilization rate and recovery efficiency of materials and has good application prospects.

[0075] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of application of the present invention should still fall within the scope of the claims of the present invention.

Claims

1. A lithium ion spraying diaphragm PVDF recovery device, characterized in that: include: A pre-processing unit, the pre-processing unit is used to process the material into particles; The pretreatment unit is connected to the dissolution unit, and the dissolution unit is used to configure the material into a solution by heating and stirring; The dissolution unit is connected to the filtration unit, the filtration unit is connected to the precipitation unit, the solution filtered by the filtration unit enters the precipitation unit, and the precipitant is used to perform solid-liquid separation; A drying unit is arranged at one side of the precipitation unit, and the drying unit is used to dry the precipitated solid in the precipitation unit.

2. A lithium ion spraying diaphragm PVDF recovery device according to claim 1, characterized in that: The pretreatment unit comprises a feed hopper (1), a crushing mechanism (11) is arranged inside the feed hopper (1), and a screening mechanism (12) is arranged below the crushing mechanism (11).

3. A lithium ion spraying diaphragm PVDF recovery device according to claim 2, characterized in that: The dissolving unit comprises a reaction kettle (2), and the feed port of the reaction kettle (2) is connected to the discharge port of the feed hopper (1).

4. A lithium ion spraying diaphragm PVDF recovery device according to claim 3, characterized in that: The reaction kettle (2) is a kettle body with a double-layer hollow structure.

5. A lithium ion spraying diaphragm PVDF recovery device according to claim 4, characterized in that: The reaction kettle (2) is provided with a stirring mechanism (21) and a heating mechanism (22), and the stirring mechanism (21) and the heating mechanism (22) cooperate to accelerate the dissolution of the material.

6. A lithium ion spraying diaphragm PVDF recovery device according to claim 4, characterized in that: The precipitation unit comprises a precipitation tank (4), and a stirring paddle (41) is arranged in the precipitation tank (4).

7. A method for recovering PVDF in a lithium ion sprayed diaphragm PVDF recovery device, characterized in that: include: S1, placing the waste lithium ion spraying diaphragm into a feed hopper (1), crushing it through a crushing mechanism (11), and screening the crushed material through a screening mechanism (12) to obtain material of standard particle size; S2, adding the screened material into the reaction kettle (2), adding an organic solvent, raising the temperature in the reaction kettle (3) to a preset temperature through the heating mechanism (5), and stirring the stirring device mechanism (21) for a preset time to fully dissolve the PVDF; S3, filtering the dissolved solution to remove insoluble impurities; S4, transporting the filtered solution to a precipitation tank (4), adding a precipitant to precipitate PVDF; S5. Place the precipitate in a drying oven (5), adjust the drying temperature and drying time, and obtain a recovered PVDF product.

8. The recycling method according to claim 7, characterized in that: In step S1, the standard particle size range is 1 mm-5 mm.

9. The recycling method according to claim 7, characterized in that: In step S2, the mass ratio of the organic solvent to the material is 5:

1.

10. The recycling method according to claim 7, characterized in that: In step S4, the volume ratio of the precipitant to the solution is 3:1.

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