A method for low-temperature and high-efficiency separation of photovoltaic modules based on dry ice-type refrigerants

Abstract

This invention provides a method for low-temperature, high-efficiency separation of photovoltaic modules using dry ice-based refrigerants. The method first requires preliminary processing of the photovoltaic module, including disassembly, to obtain a monolithic assembly mainly composed of glass, silicon wafers, and a backsheet. This monolithic assembly is then cut into blocks to be separated, which are immersed in a dry ice-based refrigerant for 30–50 seconds, maintaining a temperature of -45–-50°C during immersion. After the immersion time, the blocks are removed, and the backsheet is separated by applying external force. This invention utilizes dry ice-based refrigerants to achieve backsheet separation of photovoltaic modules in a very short time, with a separation efficiency far exceeding existing methods. Furthermore, comparative experiments show that the supersaturated CO2 gas in the dry ice-based refrigerant significantly improves the separation efficiency and effect, providing a new approach to backsheet separation of photovoltaic modules and laying the foundation for future technological development.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic module recycling technology, specifically relating to a method for low-temperature and high-efficiency separation of photovoltaic modules based on dry ice-type refrigerants. Background Technology

[0002] With rapid global economic growth and a rapidly increasing population, the demand for energy is constantly growing. However, traditional fossil fuels have drawbacks such as being non-renewable, having high carbon emissions, and polluting the environment. Excessive use of these fuels can create enormous environmental pressure and fail to meet the ever-increasing energy needs of people's production and daily life. Therefore, developing new energy sources has gradually become a common goal and consensus of the international community.

[0003] Driven by favorable energy policies and continuous advancements in photovoltaic (PV) power generation technology, the global cumulative installed PV capacity reached 1185 GW in 2022. However, the lifespan of PV modules is typically around 25 years. Therefore, the earliest installed modules are nearing the end of their lifespan and will generate a large amount of PV module waste in the future. According to the International Renewable Energy Agency (IRENA), by 2030, waste PV modules will accumulate to 8 million tons, and by 2050, this figure will reach 78 million tons. The China Photovoltaic Industry Association predicts that by around 2030, China will face the challenge of recycling 1.5 million tons of obsolete PV modules, marking the first peak in PV module retirement, and this figure will reach 20 million tons by 2050. (Cheema, HA; Ilyas, S.; Kang, H.; Kim, H., Comprehensive review of the global trends and future perspectives for recycling of decommissioned photovoltaic panels. WASTE MANAGEMENT 2024, 174, 187-202.; Li, Lin; Zhang, Yingting; Li, Long, et al. A brief analysis of the research progress on recycling of waste crystalline silicon photovoltaic modules [J]. Guangzhou Chemical Industry, 2023, 51(09): 10-12.)

[0004] Currently, crystalline silicon (c-Si) photovoltaic modules play a dominant role in the global photovoltaic module market, accounting for over 95% of all photovoltaic module types. The first batch of retired crystalline silicon photovoltaic modules can be mainly divided into several parts: aluminum alloy frame, glass, EVA encapsulation, silicon wafer, backsheet, and junction box. The aluminum alloy frame is used for reinforcement; the glass layer is used for dust prevention and to protect the silicon wafer; the EVA encapsulation is used for interlayer bonding; the backsheet is mostly a three-layer structure, with a fluorine-containing layer for UV and chemical corrosion resistance, and a PET layer that has good mechanical and electrical insulation properties, while also possessing a certain barrier function to extend battery life. These materials generally have high utilization value, thus urgently requiring efficient recycling technologies. Based on the structure and lifespan of the first batch of photovoltaic modules, a large number of photovoltaic modules with fluorine-containing backsheets will be retired in the coming years. Without a reasonable and efficient treatment plan, the polymer components will place enormous pressure on the environment. Currently, there are two main recycling approaches for effectively processing polymer components: one is overall processing, which involves mechanically removing most of the glass, followed by crushing and pulverizing, and then separating the components; the other is interlayer separation, followed by different recycling schemes for different layers. For interlayer separation, the main methods include pyrolysis to remove EVA sealant, chemical solvent swelling, and hot-blade cutting. In actual separation, auxiliary methods or a combination of methods are often used to improve efficiency, such as ultrasonic-assisted swelling, microwave-assisted swelling, and swelling-pyrolysis coupling. Green solvents are also used in the separation process, but the separation efficiency remains low, and pyrolysis produces harmful gases, indicating a lack of green and efficient separation solutions.

[0005] A search revealed that Chinese invention patent application "Disassembly Method for Decommissioned Photovoltaic Modules Based on Low-Temperature Pyrolysis" (CN115488130A) discloses a disassembly method for decommissioned photovoltaic modules based on low-temperature pyrolysis, comprising the following steps: S1, First, the decommissioned photovoltaic module is disassembled by mechanical separation to obtain an aluminum frame and junction box; S2, Next, the backsheet of the remaining part of the decommissioned photovoltaic module is placed with the backsheet facing upwards, and its surface is ground in a low-temperature environment to separate the backsheet from the other parts; S3, The remaining part of the decommissioned photovoltaic module is placed flat in a heating furnace with the glass plate facing downwards, and the temperature is continuously raised to 500°C and then kept at that temperature. At the same time, nitrogen gas is introduced into the heating furnace to cause the EVA encapsulation material to decompose in a high-temperature environment, and the glass plate and solar cell are separated. The glass plate can then be recycled.

[0006] In the aforementioned patented and existing technologies, a very small number of attempts have been made in recent years to separate the backsheet of photovoltaic modules using low-temperature process conditions. This method is greener and more environmentally friendly than traditional methods. However, this process usually requires very low temperatures (such as -196°C in the aforementioned patent application) or requires auxiliary means (such as grinding). Under these conditions, it usually takes several minutes or even tens of minutes to successfully separate the backsheet, resulting in low recycling efficiency for the large number of retired photovoltaic modules currently in use. Summary of the Invention

[0007] To address the problems in the prior art, this invention provides a method for low-temperature, high-efficiency separation of photovoltaic modules using dry ice-based refrigerants. By utilizing dry ice-based refrigerants, the backsheet of the photovoltaic module can be separated in a very short time, with a separation efficiency far exceeding that of existing separation methods. Furthermore, comparative experiments have shown that the supersaturated CO2 gas in the dry ice-based refrigerant significantly improves the separation efficiency and effect of the backsheet, providing a new approach for the backsheet separation of photovoltaic modules and laying the foundation for future technological development.

[0008] To achieve the above objectives, the present invention employs a technical solution consisting of the following technical measures.

[0009] A method for low-temperature, high-efficiency separation of photovoltaic modules based on dry ice-type refrigerants mainly includes the following steps:

[0010] (1) The photovoltaic module is subjected to preliminary processing including disassembly to obtain an integral component mainly composed of glass, silicon wafers and backsheet;

[0011] (2) The integral part obtained in step (1) is cut to obtain a block-shaped part with an outer diameter of no more than 10cm;

[0012] (3) Immerse the block to be separated obtained in step (2) in dry ice refrigerant for 30 to 50 seconds. During the immersion process, the temperature is maintained at -45 to -50℃ by adding dry ice. After the time is up, take out the block to be separated and apply an external force of 10 to 100N, including shear force and tensile force, to achieve back plate separation.

[0013] The dry ice refrigerant is a mixture of dry ice as a cold source and a low-melting-point solvent.

[0014] In this document, step (1) involves the preliminary processing of the photovoltaic module, including disassembly. This is a conventional preliminary processing method for photovoltaic modules in this technical field. It typically involves removing the aluminum alloy frame and junction box connected to the photovoltaic module. Conventional equipment recycling methods such as mechanical disassembly / separation can be used, for example, manually disassembling and removing the aluminum alloy frame and junction box. Those skilled in the art can disassemble the photovoltaic module according to its actual condition to obtain a whole component mainly composed of glass, silicon wafers, and a backsheet. If necessary, other non-whole components may also be processed by simple mechanical disassembly (e.g., referring to the disassembly of the aluminum alloy frame) to obtain the whole component described herein.

[0015] In this paper, the integral component described in step (1) is mainly composed of glass, silicon wafer and back plate. Its shape is a multi-layer plate structure. The purpose of this invention is to separate the back plate in the integral component from other layers, so as to obtain a back plate that is convenient for further processing and recycling.

[0016] In this article, the photovoltaic module mentioned in step (1) is a recyclable material that needs to be separated, recycled and reused. For example, it can be a retired / waste photovoltaic module, or it can be a scrap / defective product from the photovoltaic module production process.

[0017] In this paper, the integral component described in step (2) is cut into blocks with an outer diameter of no more than 10 cm to be separated. The purpose is to miniaturize the integral component to improve the subsequent separation efficiency. The cutting method can be either conventional equipment recycling or conventional cutting methods for sheet metal parts. It should be noted that the shape of the blocks to be separated obtained by cutting usually does not affect the efficiency of backplate separation using the method of this invention. Based on the principle of convenient cutting, in the following embodiments, the integral component is cut into rectangular blocks with a side length of no more than 10 cm to be separated.

[0018] In this paper, the dry ice-type refrigerant mentioned in step (3) is a mixture of dry ice as a cold source and a low-melting-point solvent. The low-melting-point solvent should meet the requirement that its liquid state temperature reaches -45 to -50°C after the addition of dry ice. It should be noted that the low-temperature solvent method using dry ice as a cold source is a conventional process for low-temperature baths in the chemical industry. Those skilled in the art can select a suitable low-melting-point solvent, especially a solvent with a melting point not higher than -50°C, based on the temperature parameters (-45 to -50°C) provided by this invention. However, in order to ensure the overall environmental friendliness and greenness of the separation method of this invention, the low-melting-point solvent is preferably a non-toxic / low-toxic low-melting-point solvent.

[0019] To better illustrate the present invention and provide a technical solution for reference, the low melting point solvent in step (3) is selected from any one of anhydrous ethanol, isopropanol, acetone, and ethyl acetate.

[0020] In one preferred embodiment, in order to further improve the separation efficiency, the separation block in step (3) is immersed in a dry ice-type refrigerant, and the ratio of the liquid volume to the material volume is not higher than 1 / 2.

[0021] In this paper, after taking out the block to be separated in step (3), the back plate is separated by applying an external force of 10-100N, including shear force and tensile force. It should be noted that under laboratory conditions, when the block to be separated is fixed at one end and a 1kg weight is placed at the other end, the back plate can be separated by the slight bending deformation caused by the weight. Therefore, in industrial separation, it can be separated by applying an external force including shear force and tensile force, for example, by separating the two sides of the block using a vacuum suction cup.

[0022] This invention originated from an unexpected discovery made by the inventors during the cryogenic quenching process of photovoltaic modules using liquid nitrogen. The low-temperature environment provided by liquid nitrogen and similar media could significantly and more effectively separate the backsheet. Inspired by this discovery, and considering cost factors, the inventors conducted an exploratory experiment using dry ice as a cold source and a cryogenic solvent method for immersion treatment. Surprisingly, they found that although the low-temperature environment temperature was increased from -196°C (liquid nitrogen) to -45 to -50°C, the separation efficiency and effect were significantly improved. The backsheet could be separated by simply applying external force when the immersion time was 30 to 50 seconds.

[0023] Further comparative experiments, comparing the separation results after impregnation with non-dry ice refrigerants at the same low temperature, revealed that dry ice refrigerants are significantly more effective for backsheet separation, based on the impregnation time and separation integrity. This is likely because the CO2 gas generated by dry ice as a cold source is concentrated and released at the point of separation, while the CO2 in the solvent remains supersaturated throughout the separation process (solid dry ice is always present in the system). When a low-melting-point solvent (such as anhydrous ethanol) diffuses into the photovoltaic module, its CO2 continuously escapes between layers, acting as an expansion mechanism and improving the separation efficiency and effect of the backsheet. Therefore, this invention provides a new approach to backsheet separation in photovoltaic modules and can serve as a foundation for future technological development.

[0024] It should be noted that, based on the cutting shape and size of the block to be separated, experiments have shown that the block to be separated with a smaller cutting side length (square, 3cm side length) has a more efficient backplate separation efficiency than the block to be separated with a larger cutting side length (square, 10cm side length). Even with an immersion time of less than 30s, it still exhibits excellent backplate separation performance. However, the backplate obtained from the block to be separated with a smaller side length is also correspondingly smaller, making it inconvenient to separate the backplate under external force and potentially hindering subsequent recycling of the backplate. Therefore, in one preferred technical solution, step (2) involves cutting the integral part obtained in step (1) to obtain a block to be separated with an outer diameter of 5-10cm.

[0025] The present invention has the following beneficial effects:

[0026] 1. This invention provides a method for low-temperature and high-efficiency separation of photovoltaic modules based on dry ice-type refrigerants. By utilizing dry ice-type refrigerants, the backsheet of photovoltaic modules can be separated in a very short time, and the separation efficiency is far higher than that of existing separation methods.

[0027] 2. The dry ice refrigerant used in this invention is green and environmentally friendly. It usually does not produce toxic gases or liquids during the entire separation process, making it friendly to operators. Furthermore, the dry ice refrigerant used can be reused, consuming only dry ice to maintain the temperature, making it suitable for large-scale industrial applications.

[0028] 3. Through comparative experiments, this invention has found that supersaturated CO2 gas in dry ice refrigerants is significantly beneficial to the separation efficiency and effect of the backsheet, providing a new approach for the separation of photovoltaic modules on the backsheet and laying the foundation for subsequent technological development. Attached Figure Description

[0029] Figure 1 This is a photograph showing the physical object after the backplate is separated in Embodiment 1 of the present invention.

[0030] Figure 2 This is a side-view photograph of the block to be separated in Embodiment 1 of the present invention before immersion.

[0031] Figure 3 This is a photograph showing the physical object after the backplate is separated in Embodiment 2 of the present invention.

[0032] Figure 4 This is a photograph showing the physical object after the backplate is separated in Embodiment 3 of the present invention.

[0033] Figure 5 This is a photograph showing the physical object after the backplate is separated in Embodiment 4 of the present invention.

[0034] Figure 6 This is a photograph showing the actual product after the backplate was separated in Comparative Example 1 of the present invention.

[0035] Figure 7 These are photographs showing the physical objects after the backplates were separated in Embodiment 1 and Comparative Example 2 of the present invention. The left side shows the backplate separation effect of the separation method in Embodiment 1, and the right side shows the backplate separation effect of the separation method in Comparative Example 2.

[0036] Figure 8 This is a photograph showing the actual product after the backplate separation failed in Comparative Example 3 of this invention.

[0037] Figure 9 This is a photograph of the impregnation process in Embodiment 1 of the present invention. Detailed Implementation

[0038] To further understand the present invention, preferred embodiments are described below with reference to examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims. Those skilled in the art can refer to the content of this document to appropriately improve the process parameters. In particular, it should be noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the scope of the present invention. The methods and applications of the present invention have been described through preferred embodiments, and those skilled in the art can obviously make modifications or appropriate changes and combinations to the methods and applications described herein without departing from the content, spirit and scope of the present invention to realize and apply the technology of the present invention. Although it is believed that those skilled in the art will fully understand the following terms, the following definitions are set forth to help illustrate the subject matter disclosed in the present invention.

[0039] A method for low-temperature, high-efficiency separation of photovoltaic modules based on dry ice-type refrigerants mainly includes the following steps:

[0040] (1) The photovoltaic module is subjected to preliminary processing including disassembly to obtain an integral component mainly composed of glass, silicon wafers and backsheet;

[0041] (2) The integral part obtained in step (1) is cut to obtain a block-shaped part with an outer diameter of no more than 10cm;

[0042] (3) Immerse the block to be separated obtained in step (2) in dry ice refrigerant for 30 to 50 seconds. During the immersion process, the temperature is maintained at -45 to -50℃ by adding dry ice. After the time is up, take out the block to be separated and apply an external force of 10 to 100N, including shear force and tensile force, to achieve back plate separation.

[0043] The dry ice refrigerant is a mixture of dry ice as a cold source and a low-melting-point solvent.

[0044] In this document, step (1) involves the preliminary processing of the photovoltaic module, including disassembly. This is a conventional preliminary processing method for photovoltaic modules in this technical field. It typically involves removing the aluminum alloy frame and junction box connected to the photovoltaic module. Conventional equipment recycling methods such as mechanical disassembly / separation can be used, for example, manually disassembling and removing the aluminum alloy frame and junction box. Those skilled in the art can disassemble the photovoltaic module according to its actual condition to obtain a whole component mainly composed of glass, silicon wafers, and a backsheet. If necessary, other non-whole components may also be processed by simple mechanical disassembly (e.g., referring to the disassembly of the aluminum alloy frame) to obtain the whole component described herein.

[0045] In this paper, the integral component described in step (1) is mainly composed of glass, silicon wafer and back plate. Its shape is a multi-layer plate structure. The purpose of this invention is to separate the back plate in the integral component from other layers, so as to obtain a back plate that is convenient for further processing and recycling.

[0046] In this article, the photovoltaic module mentioned in step (1) is a recyclable material that needs to be separated, recycled and reused. For example, it can be a retired / waste photovoltaic module, or it can be a scrap / defective product from the photovoltaic module production process.

[0047] In this paper, the integral component described in step (2) is cut into blocks with an outer diameter of no more than 10 cm to be separated. The purpose is to miniaturize the integral component to improve the subsequent separation efficiency. The cutting method can be either conventional equipment recycling or conventional cutting methods for sheet metal parts. It should be noted that the shape of the blocks to be separated obtained by cutting usually does not affect the efficiency of backplate separation using the method of this invention. Based on the principle of convenient cutting, in the following embodiments, the integral component is cut into rectangular blocks with a side length of no more than 10 cm to be separated.

[0048] In this paper, the dry ice-type refrigerant mentioned in step (3) is a mixture of dry ice as a cold source and a low-melting-point solvent. The low-melting-point solvent should meet the requirement that its liquid state temperature reaches -45 to -50°C after the addition of dry ice. It should be noted that the low-temperature solvent method using dry ice as a cold source is a conventional process for low-temperature baths in the chemical industry. Those skilled in the art can select a suitable low-melting-point solvent, especially a solvent with a melting point not higher than -50°C, based on the temperature parameters (-45 to -50°C) provided by this invention. However, in order to ensure the overall environmental friendliness and greenness of the separation method of this invention, the low-melting-point solvent is preferably a non-toxic / low-toxic low-melting-point solvent.

[0049] To better illustrate the present invention and to provide an embodiment for reference, the low-melting-point solvent in step (3) is selected from any one of anhydrous ethanol, isopropanol, acetone, and ethyl acetate.

[0050] In one preferred embodiment, in order to further improve the separation efficiency, the separation block in step (3) is immersed in a dry ice-type refrigerant, and the ratio of the liquid volume to the material is not higher than 1 / 2.

[0051] In this paper, after taking out the block to be separated in step (3), the back plate is separated by applying an external force of 10-100N, including shear force and tensile force. It should be noted that under laboratory conditions, when the block to be separated is fixed at one end and a 1kg weight is placed at the other end, the back plate can be separated by the slight bending deformation caused by the weight. Therefore, in industrial separation, it can be separated by applying an external force including shear force and tensile force, for example, by separating the two sides of the block using a vacuum suction cup.

[0052] This invention originated from an unexpected discovery made by the inventors during the cryogenic quenching process of photovoltaic modules using liquid nitrogen. The low-temperature environment provided by liquid nitrogen and similar media could significantly and more effectively separate the backsheet. Inspired by this discovery, and considering cost factors, the inventors conducted an exploratory experiment using dry ice as a cold source and a cryogenic solvent method for immersion treatment. Surprisingly, they found that although the low-temperature environment temperature was increased from -196°C (liquid nitrogen) to -45 to -50°C, the separation efficiency and effect were significantly improved. The backsheet could be separated by simply applying external force when the immersion time was 30 to 50 seconds.

[0053] Further comparative experiments, comparing the separation results after impregnation with non-dry ice refrigerants at the same low temperature, revealed that dry ice refrigerants are significantly more effective for backsheet separation, based on the impregnation time and separation integrity. This is likely because the CO2 gas generated by dry ice as a cold source is concentrated and released at the point of separation, while the CO2 in the solvent remains supersaturated throughout the separation process (solid dry ice is always present in the system). When a low-melting-point solvent (such as anhydrous ethanol) diffuses into the photovoltaic module, its CO2 continuously escapes between layers, acting as an expansion mechanism and improving the separation efficiency and effect of the backsheet. Therefore, this invention provides a new approach to backsheet separation in photovoltaic modules and can serve as a foundation for future technological development.

[0054] It should be noted that, based on the cutting shape and size of the block to be separated, experiments have shown that the block to be separated with a smaller cutting side length (square, 3cm side length) has a more efficient backplate separation efficiency than the block to be separated with a larger cutting side length (square, 10cm side length). Even with an immersion time of less than 30s, it still exhibits excellent backplate separation performance. However, the backplate obtained from the block to be separated with a smaller side length is also correspondingly smaller, making it inconvenient to separate the backplate under external force and potentially hindering subsequent recycling of the backplate. Therefore, in one preferred technical solution, step (2) involves cutting the integral part obtained in step (1) to obtain a block to be separated with an outer diameter of 5-10cm.

[0055] The present application will be further explained in detail below with reference to embodiments. However, those skilled in the art should understand that these embodiments are provided for illustrative purposes only and are not intended to limit the present application.

[0056] Example

[0057] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be construed as limiting the scope of this application. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Where the manufacturers of reagents or instruments are not specified, they are all commercially available conventional products. This application should not be construed as being limited to the specific embodiments described.

[0058] 1. Raw materials

[0059] Retired photovoltaic modules purchased from the secondhand market;

[0060] Anhydrous ethanol (CH3CH2OH), Shanghai Fine Chemical Reagent Co., Ltd.

[0061] Solid dry ice, Chengdu Dingsheng Times Technology Co., Ltd.

[0062] 2. Preparation method

[0063] (1) The retired photovoltaic modules are subjected to preliminary processing including dismantling. The aluminum alloy frame and junction box are removed by manual dismantling to obtain an integral component mainly composed of glass, silicon wafers and backsheet.

[0064] (2) Cut the whole piece obtained in step (1) to obtain square blocks to be separated with a side length of no more than 10cm;

[0065] (3) Immerse the block to be separated obtained in step (2) in dry ice refrigerant for 30 to 50 seconds. During the immersion process, the temperature is maintained at -45 to -50℃ by adding dry ice. After the time is up, take out the block to be separated and then apply an external force of about 10N shear force manually (hold the edge of the block to be separated with your index finger and press the middle part with your thumb) to produce a slight bending deformation, thereby achieving the separation of the back plate.

[0066] The dry ice refrigerant is a mixture of dry ice as a cold source and anhydrous ethanol.

[0067] Example 1

[0068] Example 1 is to cut a square block to be separated with a side length of 3cm in step (2) according to the above "2. Preparation method". In step (3), the immersion time is 30s. After taking it out, the back plate is separated under the action of external force.

[0069] like Figure 1 As shown, the backplane has achieved a relatively complete separation, with only a very small amount of silicon wafer remaining.

[0070] like Figure 2 As shown in the side-view photograph of the block to be separated before impregnation, the backplate is tightly bonded to the silicon wafer.

[0071] like Figure 9 As shown, CO2 gas is concentrated and released at the block to be separated during impregnation.

[0072] Example 2

[0073] Example 2 is to cut a square block to be separated with a side length of 5cm in step (2) according to the above "2. Preparation method". In step (3), the immersion time is 30s. After taking it out, the back plate is separated under the action of external force.

[0074] like Figure 3 As shown, the backplane has achieved relatively good separation, but there are still some silicon wafers and a lot of metal residue.

[0075] Example 3

[0076] Example 3 is to cut a square block to be separated with a side length of 5cm in step (2) according to the above "2. Preparation method". In step (3), the immersion time is 40s. After taking it out, the back plate is separated under the action of external force.

[0077] like Figure 4 As shown, the backplane achieved relatively good separation, and compared with Example 2, it can be seen that the metal residue was significantly reduced, but silicon wafer residue still exists.

[0078] Example 4

[0079] Example 4 is to cut a square block to be separated with a side length of 5cm in step (2) according to the above "2. Preparation method". In step (3), the immersion time is 50s. After taking it out, the back plate is separated under the action of external force.

[0080] like Figure 5 As shown, the backplane separation effect is further improved in Comparative Example 2, with reduced metal residue and no silicon wafer residue.

[0081] Comparative Example 1

[0082] Comparative Example 1 is a square block to be separated with a side length of 5cm obtained by cutting in step (2) according to the above "2. Preparation method". In step (3), the immersion time is 20s. After taking it out, the back plate is separated under the action of external force.

[0083] like Figure 6 As shown, due to the short immersion time, complete separation was difficult to achieve, leaving about a quarter of the backplate intact.

[0084] Comparative Example 2

[0085] Comparative Example 2 is based on the steps in "2. Preparation Method" above. In step (2), a square block to be separated with a side length of 3cm is cut. However, in step (3), the dry ice / anhydrous ethanol system is replaced with pure anhydrous ethanol at the same temperature. The immersion time is 45s. After removal, the back plate is separated under the action of external force.

[0086] To make a more intuitive comparison, the temperature during the impregnation process was manually controlled and kept at approximately -46°C. As a comparison, the temperature during the impregnation process was also manually controlled and kept at approximately -46°C based on the conditions of Example 1.

[0087] like Figure 7 As shown, the separation effect of Example 1 is significantly better than that of Comparative Example 2, and the immersion time of Example 1 is significantly shorter.

[0088] Comparative Example 3

[0089] Comparative Example 3 refers to the steps in "2. Preparation Method" above. In step (2), a square block to be separated with a side length of 3cm was cut. However, in step (3), the dry ice / anhydrous ethanol system was replaced with pure anhydrous ethanol at the same temperature. The immersion time was 30s. The temperature was manually controlled during the immersion process and kept at about -47℃. After being taken out, the back plate could not be separated under the action of external force.

[0090] like Figure 8 As shown, Comparative Example 3 cannot achieve separation of the backplate under external force.

[0091] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for low-temperature, high-efficiency separation of photovoltaic modules based on dry ice-type refrigerants, characterized in that... The main steps include: (1) The photovoltaic module is subjected to preliminary processing including disassembly to obtain an integral component mainly composed of glass, silicon wafers and backsheet; (2) The integral part obtained in step (1) is cut to obtain a block-shaped part with an outer diameter of no more than 10cm; (3) Immerse the block to be separated obtained in step (2) in dry ice refrigerant for 30 to 50 seconds. During the immersion process, the temperature is maintained at -45 to -50℃ by adding dry ice. After the time is up, take out the block to be separated and apply an external force of 10 to 100N, including shear force and tensile force, to achieve back plate separation. The dry ice refrigerant is a mixture of dry ice as a cold source and a low-melting-point solvent, wherein the low-melting-point solvent includes any one of anhydrous ethanol, isopropanol, acetone, and ethyl acetate.

2. The method according to claim 1, characterized in that: The photovoltaic modules mentioned in step (1) are recyclable materials that need to be separated, recycled and reused, including retired / waste photovoltaic modules and scraps / defective products from the production process.

3. The method according to claim 1, characterized in that: In step (3), the separated block is immersed in a dry ice-type refrigerant, and the ratio of the liquid volume to the material volume is not higher than 1 / 2.

4. The method according to claim 1, characterized in that: The block to be separated in step (3) is immersed in dry ice-type refrigerant for 30-40 seconds.

5. The method according to claim 1, characterized in that: In step (2), the integral part obtained in step (1) is cut to obtain a block-shaped part with an outer diameter of 5 to 10 cm.

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