Method for recovering high-purity lead halide from perovskite solar cell

Abstract

The invention discloses a method for recovering high-purity lead halide from a perovskite solar cell. The method comprises the following steps: firstly, carrying out hydroformylation on chloromethylated polystyrene resin, grafting with polyethyleneimine, and reacting with carbon disulfide to prepare selective adsorption resin; secondly, sequentially pretreating the perovskite cell with chlorobenzene to obtain a perovskite layer; immersing the perovskite layer in deionized water for ultrasonic treatment to obtain a mixed solution; adding the selective adsorption resin into the mixed solution, wherein the adsorbed liquid is an iodine-rich solution; carrying out gradient acid elution on the adsorbed resin, oxidizing through hydrogen peroxide to remove tin impurities, adjusting the pH step by step, precipitating, and dissolving to obtain a high-purity lead ion solution; finally, the pH value of the iodine-rich solution is adjusted, a high-purity lead ion solution is added for a precipitation reaction, and a high-purity lead halide product is obtained after washing and drying. The high-purity lead halide recovered by the method is high in purity and excellent in recovery efficiency.

Description

A method for recovering high-purity lead halide from perovskite solar cells Technical Field

[0001] This invention relates to the field of solar cell technology, specifically to a method for recovering high-purity lead halide from perovskite solar cells. Background Technology

[0002] Perovskite solar cells, as a next-generation photovoltaic technology, have become a research hotspot in the renewable energy field due to their significant advantages such as high photoelectric conversion efficiency, low manufacturing cost, and flexible processing, demonstrating broad application prospects. However, the soluble lead compounds commonly found in their perovskite layers pose a potential leaching risk after cell damage or disposal, which may harm the ecological environment and human health. Simultaneously, key elements such as lead and iodine are scarce resources, and the inability to effectively recover them will also lead to resource waste. Therefore, developing a method for efficiently and selectively recovering valuable components, especially high-purity lead halides, from perovskite solar cells is of great significance for reducing environmental risks, improving resource recycling rates, and promoting the sustainable development of this technology.

[0003] In recent years, with the deepening research and development of perovskite solar cells and the expectation of large-scale applications in the future, the disposal of these cells at the end of their lifespan has received increasing attention. Traditional hydrometallurgical or pyrometallurgical recycling strategies often suffer from problems such as complex processes, poor selectivity, high energy consumption, or easy generation of secondary pollution, making it difficult to achieve efficient separation and high-value recovery of lead and iodine elements in an economical and environmentally friendly manner. Summary of the Invention

[0004] The purpose of this invention is to provide a method for recovering high-purity lead halide from perovskite solar cells, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for recovering high-purity lead halide from perovskite solar cells, comprising the following steps: Step 1, preparing a selective adsorption resin; Step 2, using the selective adsorption resin to selectively adsorb lead ions from the leaching mixture of perovskite solar cells, separating an iodine-rich solution and the adsorbed selective adsorption resin, and eluting and purifying the resin to obtain a high-purity lead ion solution; Step 3, reacting the iodine-rich solution with the high-purity lead ion solution to generate high-purity lead halide.

[0006] As an optimization, the preparation method of the selective adsorption resin in step one includes: (1) mixing chloromethylated polystyrene resin, hexamethylenetetramine, deionized water and anhydrous ethanol in a mass ratio of 1:(3~3.5):(2~2.5):(3.5~4), reacting at 85~95℃ for 35~40h, adding 37% hydrochloric acid at 9.5~10.5 times the mass of chloromethylated polystyrene resin, continuing to stir for 5~10h, and obtaining aldehyde-based polystyrene resin after washing and drying; (2) mixing aldehyde-based polystyrene resin with N,N-dimethylformamide in a mass ratio of 1:(3~3.5):(2~2.5):(3.5~4), and adding 37% hydrochloric acid at 9.5~10.5 times the mass of chloromethylated polystyrene resin. Mix 1 part polystyrene resin to 8 parts polystyrene resin and react at 25-30°C for 10-15 hours. Add polyethyleneimine at 1-1.2 times the mass of the aldehyde-modified polystyrene resin, raise the temperature to 95-105°C and continue the reaction for 18-22 hours. Cool the temperature to 50-60°C, add sodium borohydride at 0.3-0.5 times the mass of the aldehyde-modified polystyrene resin, and continue the reaction for 3-4 hours. Cool the temperature to 25-30°C, add carbon disulfide at 0.6-1 times the mass of the aldehyde-modified polystyrene resin, and continue the reaction for 6-12 hours. Filter the solution and wash with anhydrous ethanol and deionized water to obtain the selective adsorption resin.

[0007] As an optimization, the reaction process of the selective adsorption resin is as follows: .

[0008] As an optimization, the perovskite layer material of the perovskite solar cell described in step two has an ABI3 structure, where A is a monovalent organic and inorganic cation CH3NH3. + MA + FA + Cs + etc.; B is a divalent metal cation Pb 2+ Sn 2+ X represents a halide anion, which is I in this case. - .

[0009] As an optimization, step two includes: a. treating the perovskite solar cell with chlorobenzene at 25-30°C for 1-1.5 hours, followed by washing with dichloromethane to obtain a pretreated perovskite solar cell; b. immersing the pretreated perovskite solar cell in deionized water at 10-12 wt%, and ultrasonically treating it at 30-40°C, 20-40 kHz, and 500-600 W for 0.5-1.5 hours, followed by filtration and centrifugation to obtain a leachate mixture; c. adding the selective adsorption resin to the leachate mixture, and performing cyclic adsorption at 25-30°C, collecting the adsorbed selective adsorption resin and the remaining liquid after adsorption as an iodine-rich solution; d. eluting the adsorbed selective adsorption resin with a gradient concentration of nitric acid aqueous solution to obtain a lead ion pickling solution; e. sequentially oxidizing and purifying the lead ion pickling solution, followed by stepwise precipitation and resolution to obtain a high-purity lead ion solution.

[0010] As an optimization, in step c, the amount of selective adsorption resin added is 0.5 to 0.9 times the mass of the pretreated perovskite solar cell, the adsorption cycle is repeated 5 times, each adsorption lasts 0.5 to 1.5 hours, and all resins loaded with lead ions are combined.

[0011] As an optimization, in step d, the concentrations of the gradient concentration nitric acid aqueous solution are 10% (v / v), 5% (v / v), 2.5% (v / v), and 1% (v / v), respectively.

[0012] As an optimization, in step e, the specific operation of oxidation to remove impurities, stepwise precipitation purification and then dissolution is as follows: add 30% hydrogen peroxide solution dropwise to the lead ion pickling solution, react at 25~30℃ for 10~20 min, adjust the pH to 2.5~3.5 with 1M sodium hydroxide, collect the supernatant by centrifugation, continue to adjust the pH to 9~10 with 1M sodium hydroxide, collect the precipitate by centrifugation, and dissolve the precipitate in 20% (v / v) dilute nitric acid at 10wt%~15wt% to obtain a high-purity lead ion solution.

[0013] As an optimization, in step e, the volume ratio of the 30% hydrogen peroxide solution to the lead ion pickling solution is 1~3mL:100mL.

[0014] As an optimization, the specific conditions for step three are as follows: the pH of the iodine-rich solution is adjusted to 2.5-3.5 with 10% (v / v) nitric acid, and the high-purity lead ion solution is added dropwise at 25-30°C with stirring. The resulting precipitate is washed and dried to obtain the high-purity lead halide.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The present invention realizes the high-purity recovery of lead halide from perovskite solar cells through the following steps: First, a selective adsorption resin with dithiocarbamate functional groups is prepared; then, the resin is used to efficiently adsorb lead ions from the leaching mixture, and an iodine-rich solution is obtained; the adsorbed lead is eluted and deeply purified to obtain a high-purity lead ion solution; finally, it is reacted with the iodine-rich solution to generate the target product.

[0016] First, a selective adsorption resin with a surface modified with a dithiocarbamate structure was designed and prepared. This group, as a typical soft base, exhibits extremely strong specific chelating ability for lead ions, enabling efficient and highly selective capture of lead ions from leaching mixtures containing multiple ions, while organic monovalent cations are largely unadsorbed, achieving initial separation of lead from most impurity ions. The adsorbed lead ions may contain a small amount of tin, which is also a soft acid divalent cation. Therefore, hydrogen peroxide treatment was introduced in the subsequent purification step: hydrogen peroxide selectively oxidizes the potentially coexisting divalent tin to tetravalent tin, while lead ions remain stable under these conditions; tetravalent tin is completely precipitated as hydrated tin oxide at approximately pH 3, which is effectively removed by centrifugation, ensuring the high purity of the lead solution.

[0017] Secondly, in the final synthesis stage, the reaction is controlled under acidic conditions (pH 2.5–3.5). Under these conditions, the precipitation reaction of lead iodide by combining iodide ions with lead ions is the only dominant thermodynamic process, and other possible side reactions are effectively suppressed. This ensures the direct regeneration of high-purity lead iodide precipitate from high-purity lead ion solution and iodine-rich solution, with a purity directly meeting the requirements for reuse in the preparation of perovskite active materials. In summary, the entire process achieves efficient separation and high-value recovery of lead and iodine elements through the synergistic effect of "selective adsorption-oxidative impurity removal-acidic precipitation," and the process is simple and environmentally friendly. Attached Figure Description

[0018] Figure 1 shows the XRD patterns of high-purity lead iodide obtained in Example 2 and commercially available lead iodide. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] To more clearly illustrate the method provided by the present invention, the following embodiments will be described in detail.

[0021] Example 1: A method for recovering high-purity lead halide from perovskite solar cells, comprising the following steps: Step 1: Mixing chloromethylated polystyrene resin, hexamethylenetetramine, deionized water, and anhydrous ethanol in a mass ratio of 1:3:2:3.5, stirring at 85°C for 35 hours, adding 37% hydrochloric acid at 9.5 times the mass of the chloromethylated polystyrene resin, continuing stirring for 5 hours, filtering, washing with anhydrous ethanol and deionized water until the washing solution is neutral, and drying to obtain aldehyde-modified polystyrene resin; mixing the aldehyde-modified polystyrene resin with N,N-dimethylformamide in a mass ratio of 1:8, stirring at 25°C for 10 hours, adding the aldehyde-modified polystyrene resin One part by weight of polyethyleneimine was heated to 95°C and stirred for 18 hours. The temperature was then lowered to 50°C, and 0.3 times the weight of sodium borohydride (alternatively aldehyde-modified polystyrene resin) was added. The mixture was stirred for 3 hours, then cooled to 25°C, and 0.6 times the weight of carbon disulfide (alternatively aldehyde-modified polystyrene resin) was added. The mixture was stirred for 6 hours, filtered, and washed with anhydrous ethanol and deionized water to obtain a selective adsorption resin. In step two, the perovskite solar cell was immersed in chlorobenzene and stirred at 25°C for 1 hour. It was then washed with dichloromethane to obtain a pretreated perovskite solar cell. The pretreated perovskite solar cell was then immersed in deionized water at 10 wt% concentration, ultrasonically treated for 0.5 hours, filtered, and centrifuged. The liquid was collected to obtain a leaching mixture. Selective adsorption resin (0.5 times the mass of the pretreated perovskite solar cell) was added to the leaching mixture, and the mixture was stirred at 25°C for 0.5 h for adsorption. The adsorbed selective adsorption resin was collected, and fresh selective adsorption resin was added back to the leaching mixture. This cycle was repeated 5 times. The adsorbed selective adsorption resins were combined, and the remaining liquid (iodine-rich solution) was collected. The adsorbed selective adsorption resin was then sequentially mixed with nitric acid aqueous solutions of varying concentrations. After each mixing, the mixture was stirred at 25°C for 1 h. The liquids were filtered and collected, and combined to obtain a lead ion pickling solution. Droplets were added to the lead ion pickling solution... Add 30% hydrogen peroxide solution, with the amount of 30% hydrogen peroxide solution added being 1 mL per 100 mL of lead ion pickling solution. Stir at 25℃ for 10 min, adjust the pH to 2.5 with 1M sodium hydroxide, centrifuge and collect the supernatant, continue to adjust the pH to 9 with 1M sodium hydroxide, centrifuge and collect the precipitate, dissolve the precipitate at 10 wt% in 20% (v / v) dilute nitric acid to obtain a high-purity lead ion solution; Step 3: Adjust the pH of the iodine-rich solution to 2.5 with 10% (v / v) nitric acid, add the high-purity lead ion solution dropwise while stirring at 25℃, and wash the resulting yellow precipitate twice alternately with distilled water and methanol, dry it, and obtain high-purity lead halide.

[0022] Example 2: A method for recovering high-purity lead halide from perovskite solar cells, comprising the following steps: Step 1: Mixing chloromethylated polystyrene resin, hexamethylenetetramine, deionized water, and anhydrous ethanol at a mass ratio of 1:3.3:2.3:3.8, stirring at 90°C for 37 hours, adding 10 times the mass of chloromethylated polystyrene resin in 37% hydrochloric acid, continuing stirring for 8 hours, filtering, washing with anhydrous ethanol and deionized water until the washing solution is neutral, and drying to obtain aldehyde-modified polystyrene resin; mixing aldehyde-modified polystyrene resin with N,N-dimethylformamide at a mass ratio of 1:10, stirring at 27°C for 12 hours, and adding aldehyde-modified polystyrene... Polyethyleneimine (1.1 times the weight of resin) was added, heated to 100℃ and stirred for 20 hours, then cooled to 55℃. Sodium borohydride (0.4 times the weight of aldehyde-modified polystyrene resin) was added and stirred for 3.5 hours. The temperature was then lowered to 27℃, and carbon disulfide (0.8 times the weight of aldehyde-modified polystyrene resin) was added and stirred for 10 hours. The mixture was filtered, washed with anhydrous ethanol and deionized water to obtain a selective adsorption resin. In step two, the perovskite solar cell was immersed in chlorobenzene and stirred at 27℃ for 1.5 hours, then washed with dichloromethane to obtain a pretreated perovskite solar cell. The pretreated perovskite solar cell was then immersed in deionized water at 11 wt% and ultrasonically treated for 1 hour. h, filter, centrifuge, collect the liquid to obtain a leaching mixture; add 0.7 times the mass of the pretreated perovskite solar cell selective adsorption resin to the leaching mixture, stir at 27℃ for 1 h, collect the adsorbed selective adsorption resin, and add fresh selective adsorption resin back to the leaching mixture, repeating the cycle 5 times, combine the adsorbed selective adsorption resin, and collect the remaining liquid, which is an iodine-rich solution; mix the adsorbed selective adsorption resin sequentially with nitric acid aqueous solutions of gradient concentrations, stirring at 27℃ for 1.3 h after each mixing, filter and collect the liquid, combine, to obtain a lead ion pickling solution; add lead ion acid... Add 30% hydrogen peroxide solution dropwise to the washing solution, with 2 mL of 30% hydrogen peroxide solution added per 100 mL of lead ion pickling solution. Stir at 27℃ for 15 min, adjust the pH to 3 with 1M sodium hydroxide, centrifuge and collect the supernatant. Continue to adjust the pH to 9.5 with 1M sodium hydroxide, centrifuge and collect the precipitate. Dissolve the precipitate at 13 wt% in 20% (v / v) dilute nitric acid to obtain a high-purity lead ion solution. Step 3: Adjust the pH of the iodine-rich solution to 3 with 10% (v / v) nitric acid, add the high-purity lead ion solution dropwise while stirring at 27℃. The resulting yellow precipitate is washed three times alternately with distilled water and methanol, and dried to obtain high-purity lead halide.

[0023] Example 3: A method for recovering high-purity lead halide from perovskite solar cells, comprising the following steps: Step 1: Mixing chloromethylated polystyrene resin, hexamethylenetetramine, deionized water, and anhydrous ethanol at a mass ratio of 1:3.5:2.5:4, stirring at 95°C for 40 hours, adding 10.5 times the mass of chloromethylated polystyrene resin in 37% hydrochloric acid, continuing stirring for 10 hours, filtering, washing with anhydrous ethanol and deionized water until the washing solution is neutral, and drying to obtain aldehyde-modified polystyrene resin; mixing aldehyde-modified polystyrene resin with N,N-dimethylformamide at a mass ratio of 1:12, stirring at 30°C for 15 hours, and adding aldehyde-modified polystyrene... Polyethyleneimine, 1.2 times the weight of the resin, was heated to 105℃ and stirred for 22 hours. The temperature was then lowered to 60℃, and sodium borohydride, 0.5 times the weight of the aldehyde-modified polystyrene resin, was added. Stirring continued for 4 hours. The temperature was then lowered to 30℃, and carbon disulfide, 1 times the weight of the aldehyde-modified polystyrene resin, was added. Stirring continued for 12 hours. The mixture was filtered, washed with anhydrous ethanol and deionized water to obtain the selective adsorption resin. In step two, the perovskite solar cell was immersed in chlorobenzene and stirred at 30℃ for 1.5 hours. It was then washed with dichloromethane to obtain a pretreated perovskite solar cell. The pretreated perovskite solar cell was then immersed in deionized water at 12 wt% and ultrasonically treated for 1.5 hours. Filter and centrifuge to collect the liquid and obtain a leaching mixture. Add 0.9 times the mass of the pretreated perovskite solar cell selective adsorption resin to the leaching mixture and stir at 30°C for 1.5 h. Collect the adsorbed selective adsorption resin and add fresh selective adsorption resin back to the leaching mixture. Repeat this cycle 5 times. Combine the adsorbed selective adsorption resin and collect the remaining liquid, which is an iodine-rich solution. Sequentially mix the adsorbed selective adsorption resin with nitric acid aqueous solutions of varying concentrations. Stir at 30°C for 1.5 h after each mixing. Filter and collect the liquid, combine the liquids, and obtain a lead ion pickling solution. Add the lead ion pickling solution... Add 30% hydrogen peroxide solution dropwise to the lead ion pickling solution. The amount of 30% hydrogen peroxide solution added is 3 mL per 100 mL of lead ion pickling solution. Stir at 30℃ for 20 min. Adjust the pH to 3.5 with 1M sodium hydroxide. Centrifuge and collect the supernatant. Continue to adjust the pH to 10 with 1M sodium hydroxide. Centrifuge and collect the precipitate. Dissolve the precipitate in 20% (v / v) dilute nitric acid at 15 wt% to obtain a high-purity lead ion solution. Step 3: Adjust the pH of the iodine-rich solution to 3.5 with 10% (v / v) nitric acid. Add the high-purity lead ion solution dropwise while stirring at 30℃. The resulting yellow precipitate is washed 4 times alternately with distilled water and methanol. Dry to obtain high-purity lead halide.

[0024] Comparative Example 1: The only difference from Example 2 is the second step. The original step of "adding 0.9 times the mass of the pretreated perovskite solar cell selective adsorption resin to the leaching mixture, stirring and adsorbing at 30°C for 1.5 hours, collecting the adsorbed selective adsorption resin, and adding fresh selective adsorption resin back into the leaching mixture, repeating the cycle 5 times, combining the adsorbed selective adsorption resin, and collecting the remaining liquid, which is an iodine-rich solution" was changed to "adding 0.9 times the mass of the pretreated perovskite solar cell selective adsorption resin to the leaching mixture, stirring and adsorbing at 30°C for 1.5 hours, collecting the adsorbed selective adsorption resin, and adding fresh selective adsorption resin back into the leaching mixture, repeating the cycle 2 times, combining the adsorbed selective adsorption resin, and collecting the remaining liquid, which is an iodine-rich solution".

[0025] Comparative Example 2: The only difference from Example 2 is the second step. The original step of "adding 0.9 times the mass of the pretreated perovskite solar cell selective adsorption resin to the leaching mixture, stirring and adsorbing at 30°C for 1.5 hours, collecting the adsorbed selective adsorption resin, and adding fresh selective adsorption resin back into the leaching mixture, repeating the cycle 5 times, combining the adsorbed selective adsorption resin, and collecting the remaining liquid, which is an iodine-rich solution" was changed to "adding 0.9 times the mass of the pretreated perovskite solar cell selective adsorption resin to the leaching mixture, stirring and adsorbing at 30°C for 1.5 hours, collecting the adsorbed selective adsorption resin, and adding fresh selective adsorption resin back into the leaching mixture, repeating the cycle 3 times, combining the adsorbed selective adsorption resin, and collecting the remaining liquid, which is an iodine-rich solution".

[0026] Comparative Example 3: The only difference from Example 2 is the second step. The original step of "adding 0.9 times the mass of the pretreated perovskite solar cell selective adsorption resin to the leaching mixture, stirring and adsorbing at 30°C for 1.5 hours, collecting the adsorbed selective adsorption resin, and adding fresh selective adsorption resin back into the leaching mixture, repeating the cycle 5 times, combining the adsorbed selective adsorption resin, and collecting the remaining liquid, which is an iodine-rich solution" was changed to "adding 0.9 times the mass of the pretreated perovskite solar cell selective adsorption resin to the leaching mixture, stirring and adsorbing at 30°C for 1.5 hours, collecting the adsorbed selective adsorption resin, and adding fresh selective adsorption resin back into the leaching mixture, repeating the cycle 4 times, combining the adsorbed selective adsorption resin, and collecting the remaining liquid, which is an iodine-rich solution".

[0027] Comparative Example 4: The only difference from Example 2 is the second step. The original step of "adding 0.9 times the mass of the pretreated perovskite solar cell selective adsorption resin to the leaching mixture, stirring and adsorbing at 30°C for 1.5 hours, collecting the adsorbed selective adsorption resin, and adding fresh selective adsorption resin back into the leaching mixture, repeating the cycle 5 times, combining the adsorbed selective adsorption resin, and collecting the remaining liquid, which is an iodine-rich solution" was changed to "adding 0.9 times the mass of the pretreated perovskite solar cell selective adsorption resin to the leaching mixture, stirring and adsorbing at 30°C for 1.5 hours, collecting the adsorbed selective adsorption resin, and adding fresh selective adsorption resin back into the leaching mixture, repeating the cycle 6 times, combining the adsorbed selective adsorption resin, and collecting the remaining liquid, which is an iodine-rich solution".

[0028] Comparative Example 5: A method for recovering high-purity lead halide from perovskite solar cells, comprising the following steps: Step 1: Immersing the perovskite solar cell in chlorobenzene, stirring at 27°C for 1.5 h, and washing with dichloromethane to obtain a pretreated perovskite solar cell; Immersing the pretreated perovskite solar cell in deionized water at 11 wt%, sonicating for 1 h, filtering, centrifuging, collecting the liquid, and obtaining a leaching mixture; Adding 0.7 times the mass of the pretreated perovskite solar cell to the leaching mixture, stirring and adsorbing at 27°C for 1 h, collecting the adsorbed commercially available carboxyl cation exchange resin (D110 type), and adding fresh commercially available carboxyl cation exchange resin (D110 type) back to the leaching mixture, repeating the cycle 5 times, combining the adsorbed commercially available carboxyl cation exchange resin (D110 type), and collecting the remaining liquid. The liquid is an iodine-rich solution. The adsorbed commercially available carboxyl cation exchange resin (D110 type) is sequentially mixed with nitric acid aqueous solutions of varying concentrations. After each mixing, the mixture is stirred at 27°C for 1.3 hours. The liquids are collected by filtration and combined to obtain a lead ion pickling solution. A 30% hydrogen peroxide solution is added dropwise to the lead ion pickling solution at a rate of 2 mL per 100 mL of lead ion pickling solution. The mixture is stirred at 27°C for 15 minutes. The pH is adjusted to 3 with 1M sodium hydroxide. The supernatant is collected by centrifugation. The pH is further adjusted to 9.5 with 1M sodium hydroxide. The precipitate is collected by centrifugation. The precipitate is dissolved at 13 wt% in 20% (v / v) dilute nitric acid to obtain a high-purity lead ion solution. In step two, the pH of the iodine-rich solution is adjusted to 3 with (v / v) nitric acid. The high-purity lead ion solution is added dropwise while stirring at 27°C. The resulting yellow precipitate is washed three times alternately with distilled water and methanol, and then dried to obtain high-purity lead halide.

[0029] Comparative Example 6: A method for recovering high-purity lead halide from perovskite solar cells, comprising the following steps: Step 1: Mixing chloromethylated polystyrene resin, hexamethylenetetramine, deionized water, and anhydrous ethanol at a mass ratio of 1:3.3:2.3:3.8, stirring at 90°C for 37 h, adding 10 times the mass of chloromethylated polystyrene resin in 37% hydrochloric acid, continuing stirring for 8 h, filtering, washing with anhydrous ethanol and deionized water until the washings are neutral, and drying to obtain aldehyde-modified polystyrene resin; mixing aldehyde-modified polystyrene resin with N,N-dimethylformamide at a mass ratio of 1:10, stirring at 27°C for 12 h, adding aldehyde-modified polystyrene... Polyethyleneimine (1.1 times the mass of ethylene resin) was heated to 100℃ and stirred for 20 hours. The temperature was then lowered to 55℃, and sodium borohydride (0.4 times the mass of aldehyde-modified polystyrene resin) was added. Stirring continued for 3.5 hours, and the temperature was lowered to 27℃. Carbon disulfide (0.8 times the mass of aldehyde-modified polystyrene resin) was added. Stirring continued for 10 hours, and the mixture was filtered and washed with anhydrous ethanol and deionized water to obtain a selective adsorption resin. In step two, perovskite solar cells were immersed in chlorobenzene and stirred at 27℃ for 1.5 hours. They were then washed with dichloromethane to obtain pretreated perovskite solar cells. The pretreated perovskite solar cells were then immersed in deionized water at 11 wt% and ultrasonically treated. After processing for 1 hour, the solution was filtered, centrifuged, and the liquid was collected to obtain a leaching mixture. 0.7 times the mass of the pretreated perovskite solar cell's selective adsorption resin was added to the leaching mixture, and the mixture was stirred at 27°C for 1 hour. The adsorbed selective adsorption resin was collected, and fresh selective adsorption resin was added back to the leaching mixture. This cycle was repeated 5 times. The adsorbed selective adsorption resins were combined, and the remaining liquid (an iodine-rich solution) was collected. The adsorbed selective adsorption resin was mixed with a 5% (v / v) nitric acid aqueous solution and stirred at 27°C for 1.3 hours. The liquid was filtered, collected, and combined to obtain a lead ion pickling solution. Lead ion pickling was then performed. Add 30% hydrogen peroxide solution dropwise to the solution, with the amount of 30% hydrogen peroxide solution added being 2 mL per 100 mL of lead ion pickling solution. Stir at 27℃ for 15 min, adjust the pH to 3 with 1M sodium hydroxide, centrifuge and collect the supernatant, continue to adjust the pH to 9.5 with 1M sodium hydroxide, centrifuge and collect the precipitate, dissolve the precipitate at 13 wt% in 20% (v / v) dilute nitric acid to obtain a high-purity lead ion solution; Step 3, adjust the pH of the iodine-rich solution to 3 with 10% (v / v) nitric acid, add the high-purity lead ion solution dropwise while stirring at 27℃, and wash the resulting yellow precipitate three times alternately with distilled water and methanol, and dry to obtain high-purity lead halide.

[0030] Comparative Example 7: A method for recovering high-purity lead halide from perovskite solar cells, comprising the following steps: Step 1: Mixing chloromethylated polystyrene resin, hexamethylenetetramine, deionized water, and anhydrous ethanol at a mass ratio of 1:3.3:2.3:3.8, stirring at 90°C for 37 h, adding 10 times the mass of chloromethylated polystyrene resin in 37% hydrochloric acid, continuing stirring for 8 h, filtering, washing with anhydrous ethanol and deionized water until the washing solution is neutral, and drying to obtain aldehyde-modified polystyrene resin; mixing the aldehyde-modified polystyrene resin with N,N-dimethylformamide at a mass ratio of 1:10. The mixture was stirred at 27°C for 12 hours, then polyethyleneimine (1.1 times the mass of aldehyde-modified polystyrene resin) was added. The temperature was raised to 100°C and stirred for another 20 hours. The temperature was lowered to 55°C, then sodium borohydride (0.4 times the mass of aldehyde-modified polystyrene resin) was added and stirred for another 3.5 hours. The temperature was lowered to 27°C, then carbon disulfide (0.8 times the mass of aldehyde-modified polystyrene resin) was added and stirred for another 10 hours. The mixture was filtered, washed with anhydrous ethanol and deionized water to obtain the selective adsorption resin. Step two: The perovskite solar cell was immersed in chlorobenzene and stirred at 27°C for 1.5 hours. It was then washed with dichloromethane to obtain the pretreated... Perovskite solar cells; pretreated perovskite solar cells were immersed in deionized water at 11 wt%, ultrasonically treated for 1 h, filtered, centrifuged, and the liquid was collected to obtain a leaching mixture; 0.7 times the mass of the pretreated perovskite solar cells' selective adsorption resin was added to the leaching mixture, and the mixture was stirred at 27 °C for 1 h for adsorption. The adsorbed selective adsorption resin was collected, and fresh selective adsorption resin was added back to the leaching mixture. This cycle was repeated 5 times. The adsorbed selective adsorption resins were combined, and the remaining liquid was collected. This remaining liquid was an iodine-rich solution; the adsorbed selective... The adsorption resin was sequentially mixed with nitric acid aqueous solutions of varying concentrations. After each mixing, the mixture was stirred at 27°C for 1.3 h. The liquids were collected by filtration and combined to obtain a lead ion pickling solution. The pH of the lead ion pickling solution was adjusted to 9.5 with 1M sodium hydroxide. The precipitate was collected by centrifugation and dissolved at 13 wt% in 20% (v / v) dilute nitric acid to obtain a high-purity lead ion solution. In step three, the pH of the iodine-rich solution was adjusted to 3 with 10% (v / v) nitric acid. The high-purity lead ion solution was added dropwise with stirring at 27°C. The resulting yellow precipitate was washed three times alternately with distilled water and methanol and dried to obtain high-purity lead halide.

[0031] Comparative Example 8: A method for recovering high-purity lead halide from perovskite solar cells, comprising the following steps: Step 1: Mixing chloromethylated polystyrene resin, hexamethylenetetramine, deionized water, and anhydrous ethanol at a mass ratio of 1:3.3:2.3:3.8, stirring at 90°C for 37 h, adding 10 times the mass of chloromethylated polystyrene resin in 37% hydrochloric acid, continuing stirring for 8 h, filtering, washing with anhydrous ethanol and deionized water until the washings are neutral, and drying to obtain aldehyde-modified polystyrene resin; mixing aldehyde-modified polystyrene resin with N,N-dimethylformamide at a mass ratio of 1:10, stirring at 27°C for 12 h, adding aldehyde-modified... Polyethyleneimine, at 1.1 times the mass of polystyrene resin, was heated to 100℃ and stirred for 20 hours. The temperature was then lowered to 55℃, and sodium borohydride, at 0.4 times the mass of aldehyde-modified polystyrene resin, was added. Stirring continued for 3.5 hours, and the temperature was lowered to 27℃. Carbon disulfide, at 0.8 times the mass of aldehyde-modified polystyrene resin, was added. Stirring continued for 10 hours, and the mixture was filtered and washed with anhydrous ethanol and deionized water to obtain a selective adsorption resin. In step two, the perovskite solar cell was immersed in chlorobenzene and stirred at 27℃ for 1.5 hours, then washed with dichloromethane to obtain a pretreated perovskite solar cell. The pretreated perovskite solar cell was then immersed in deionized water at 11 wt% concentration. In water, the solution was ultrasonically treated for 1 hour, filtered, centrifuged, and the liquid was collected to obtain a leachate mixture. Selective adsorption resin at 0.7 times the mass of the pretreated perovskite solar cells was added to the leachate mixture, and the mixture was stirred at 27°C for 1 hour to adsorb the resin. The adsorbed selective adsorption resin was collected, and fresh selective adsorption resin was added back to the leachate mixture. This cycle was repeated 5 times. The adsorbed selective adsorption resin was combined, and the remaining liquid (iodine-rich solution) was collected. The adsorbed selective adsorption resin was then sequentially mixed with nitric acid aqueous solutions of varying concentrations. After each mixture, the mixture was stirred at 27°C for 1.3 hours, filtered, and the liquids were combined to obtain the final product. Lead ion pickling solution; Add 30% hydrogen peroxide solution dropwise to the lead ion pickling solution, the amount of 30% hydrogen peroxide solution added is 2 mL per 100 mL of lead ion pickling solution, stir at 27℃ for 15 min, adjust the pH to 3 with 1M sodium hydroxide, centrifuge and collect the supernatant, continue to adjust the pH to 9.5 with 1M sodium hydroxide, centrifuge and collect the precipitate, dissolve the precipitate at 13 wt% in 20% (v / v) dilute nitric acid to obtain a high-purity lead ion solution; Step 3, under stirring at 27℃, add the high-purity lead ion solution dropwise to the iodine-rich solution, the resulting yellow precipitate is washed 3 times alternately with distilled water and methanol, dried to obtain high-purity lead halide.

[0032] Example 1: Determination of the Optimal Adsorption Cycles of Selective Adsorption Resin. Test Method: Analysis was performed using lead ion concentration. The concentration of lead ions in the remaining iodine-rich solution after the selective adsorption resin cycle was measured using high-resolution inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0033] The results are shown in Table 1.

[0034] Table 1 A comparison of Example 2 and Comparative Examples 1-4 reveals that the lead ion concentration in the iodine-rich solution continuously decreases with increasing cycle count, but stabilizes after 5 cycles. This is because the resin has a limited adsorption capacity, and the adsorption driving force weakens as the liquid phase ion concentration decreases. The first few cycles efficiently remove most of the lead ions, but the removal efficiency of subsequent cycles drops significantly due to the low residual lead ion concentration in the solution. Therefore, 5 cycles achieve deep purification while avoiding excessive degradation of operational efficiency.

[0035] Experimental Example 2: Concentration of Lead Ions and Purity of Lead Iodide Recovered by Methods of Each Example and Comparative Examples 5-8 Lead Ion Concentration Test Method: The high-purity lead ion solutions obtained by the methods of each example and comparative examples 5-8 were tested for lead ion concentration using a high-resolution inductively coupled plasma atomic emission spectrometer.

[0036] Lead iodide purity test: The high-purity lead iodide obtained by the methods of each embodiment and Comparative Examples 5 to 8 was added to concentrated nitric acid at 0.3wt% to 0.4wt%, and digested at 130°C until the sample was completely dissolved. The resulting digestion solution was sent to an inductively coupled plasma atomic emission spectrometer to test the content of lead ions and other elements, and the purity was calculated.

[0037] The purity of lead iodide is calculated as follows: (measured lead content / theoretical lead content in lead iodide) × 100%; the results are shown in Table 2.

[0038] Table 2 A comparison of Examples 1-3 and Comparative Example 5 reveals that replacing the selective adsorption resin in step (2) with a commercially available carboxyl cation exchange resin (type D110) significantly reduces the lead ion concentration and increases impurities in the high-purity lead ion solution, thereby significantly decreasing the purity of the synthesized lead iodide. This is because ordinary carboxyl resins primarily rely on the ion exchange of carboxylic acid groups, resulting in relatively small differences in selectivity for different cations, making it difficult to effectively distinguish lead ions from potential impurity ions in the leachate. Therefore, when using ordinary resins, impurity ions compete for adsorption and are eluted along with the lead, entering the lead ion solution and ultimately contaminating the lead halide product during the precipitation step.

[0039] A comparison of Examples 1-3 and Comparative Example 6 reveals that using a single concentration for elution leads to a decrease in the lead ion concentration in the resulting high-purity lead ion solution and a decrease in the purity of the final synthesized lead iodide. Gradient concentration nitric acid elution, through a change in acidity from high to low, enables selective stepwise elution—first, a lower acidity is used to elute some weakly adsorbed impurities, then a suitable acidity is used to efficiently elute the target lead ions, and finally, a higher acidity is used to remove strongly adsorbed residual ions, thereby achieving deep purification while ensuring high elution efficiency.

[0040] A comparison of Examples 1-3 and Comparative Example 7 reveals that hydrogen peroxide treatment ensures the high purity of the lead solution. Divalent tin ions and lead ions have similar chemical properties and will be enriched together in the lead ion pickling solution during adsorption and elution steps. Hydrogen peroxide selectively oxidizes divalent tin to tetravalent tin, which can be completely precipitated as hydrated tin oxide under weakly acidic conditions. Lead ions remain stable under these conditions and exist in the solution in ionic form. Centrifugation effectively removes tin impurities, ensuring the extremely high purity of the resulting lead ion solution and the redeprecipitated lead iodide.

[0041] A comparison of Examples 1-3 and Comparative Example 8 reveals that the purity of the final lead iodide product decreases significantly if mixing is not performed under acidic conditions of pH 2.5-3.5. In an acidic environment, the reaction of iodide ions combining with lead ions to form lead iodide precipitate exhibits high specificity; simultaneously, acidic conditions prevent iodide ions from being oxidized by air or from undergoing side reactions with trace amounts of other metal ions in the solution.

[0042] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and not restrictive.

Claims

1. A method for recovering high-purity lead halide from perovskite solar cells, characterized in that, Includes the following steps: Step 1: Prepare a selective adsorption resin; Step 2: Use the selective adsorption resin to selectively adsorb lead ions from the leaching mixture of perovskite solar cells, and separate the iodine-rich solution and the adsorbed selective adsorption resin. After elution and purification, the resin yields a high-purity lead ion solution; Step 3: React the iodine-rich solution with the high-purity lead ion solution to generate high-purity lead halide.

2. The method for recovering high-purity lead halide from perovskite solar cells according to claim 1, characterized in that, The method for preparing the selective adsorption resin described in step one includes: (1) mixing chloromethylated polystyrene resin, hexamethylenetetramine, deionized water and anhydrous ethanol in a mass ratio of 1:(3~3.5):(2~2.5):(3.5~4), reacting at 85~95℃ for 35~40h, adding 9.5~10.5 times the mass of chloromethylated polystyrene resin in 37% hydrochloric acid, continuing to stir for 5~10h, and obtaining aldehyde-modified polystyrene resin after washing and drying; (2) mixing aldehyde-modified polystyrene resin with N,N-dimethylformamide in a mass ratio of 1: Mix (8~12) and react at 25~30℃ for 10~15h. Add polyethyleneimine at 1~1.2 times the mass of aldehyde-modified polystyrene resin, heat to 95~105℃ and continue reacting for 18~22h. Cool to 50~60℃, add sodium borohydride at 0.3~0.5 times the mass of aldehyde-modified polystyrene resin, and continue reacting for 3~4h. Cool to 25~30℃, add carbon disulfide at 0.6~1 times the mass of aldehyde-modified polystyrene resin, and continue reacting for 6~12h. Filter, wash with anhydrous ethanol and deionized water to obtain selective adsorption resin.

3. The method for recovering high-purity lead halide from perovskite solar cells according to claim 2, characterized in that, The reaction process of the selective adsorption resin is as follows: 。 4. The method for recovering high-purity lead halide from perovskite solar cells according to claim 1, characterized in that, The perovskite layer material of the perovskite solar cell described in step two has an ABI3 structure, where A is a monovalent organic and inorganic cation CH3NH3. + MA + FA + Cs + etc.; B is a divalent metal cation Pb 2+ Sn 2+ X represents a halide anion, which is I in this case. - .

5. The method for recovering high-purity lead halide from perovskite solar cells according to claim 1, characterized in that, Step two includes: a. treating the perovskite solar cell with chlorobenzene at 25-30°C for 1-1.5 hours, followed by washing with dichloromethane to obtain a pretreated perovskite solar cell; b. immersing the pretreated perovskite solar cell in deionized water at 10-12 wt%, and ultrasonically treating it at 30-40°C, 20-40 kHz, and 500-600 W for 0.5-1.5 hours, followed by filtration and centrifugation to obtain a leachate mixture; c. adding the selective adsorption resin to the leachate mixture, and performing cyclic adsorption at 25-30°C, collecting the adsorbed selective adsorption resin and the remaining liquid as an iodine-rich solution; d. eluting the adsorbed selective adsorption resin with a gradient concentration of nitric acid aqueous solution to obtain a lead ion pickling solution; e. sequentially oxidizing and purifying the lead ion pickling solution, followed by stepwise precipitation and resolution to obtain a high-purity lead ion solution.

6. The method for recovering high-purity lead halide from perovskite solar cells according to claim 5, characterized in that, In step c, the amount of selective adsorption resin added is 0.5 to 0.9 times the mass of the pretreated perovskite solar cell, the adsorption cycle is repeated 5 times, each adsorption lasts 0.5 to 1.5 hours, and all resins loaded with lead ions are combined.

7. A method for recovering high-purity lead halide from perovskite solar cells according to claim 5, characterized in that, In step d, the concentrations of the gradient concentration nitric acid aqueous solutions are 10% (v / v), 5% (v / v), 2.5% (v / v), and 1% (v / v), respectively.

8. A method for recovering high-purity lead halide from perovskite solar cells according to claim 5, characterized in that, In step e, the specific operation of oxidation to remove impurities, stepwise precipitation purification and then dissolution is as follows: 30% hydrogen peroxide solution is added dropwise to the lead ion pickling solution, and the reaction is carried out at 25~30℃ for 10~20 min. The pH is adjusted to 2.5~3.5 with 1M sodium hydroxide, the supernatant is collected by centrifugation, the pH is adjusted to 9~10 with 1M sodium hydroxide, the precipitate is collected by centrifugation, and the precipitate is dissolved in 20% (v / v) dilute nitric acid at 10wt%~15wt% to obtain a high-purity lead ion solution.

9. A method for recovering high-purity lead halide from perovskite solar cells according to claim 8, characterized in that, In step e, the volume ratio of the 30% hydrogen peroxide solution to the lead ion pickling solution is 1~3mL:100mL.

10. The method according to claim 1, characterized in that, The specific conditions for step three are as follows: the pH of the iodine-rich solution is adjusted to 2.5-3.5 with 10% (v / v) nitric acid, and the high-purity lead ion solution is added dropwise at 25-30°C with stirring. The resulting precipitate is washed and dried to obtain the high-purity lead halide.

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