Method for recycling cell pieces in waste photovoltaic module, cell piece and photovoltaic module

Abstract

The application discloses a recycling method of waste photovoltaic modules, comprising the following steps: removing the back plate on the waste photovoltaic module; slotting and / or punching the back of the waste photovoltaic module after removing the back plate; starting a tunnel furnace, preheating the tunnel furnace to 300-500 DEG C, then putting the waste photovoltaic module into the tunnel furnace and heating for 30-60 min; conveying the waste photovoltaic module to a cooling area, cooling to room temperature, and taking out the battery piece after the encapsulation adhesive film loses adhesion. The application provides a complete recycling method of battery pieces in waste photovoltaic modules, which does not produce harmful gases during the recycling process; the recycling process is short and the cost is low; the integrity rate of the recycled battery pieces can be as high as 96% or more; the grid lines and passivation layers of the recycled battery pieces are not damaged, and can be directly used for the preparation of new modules.

Description

Technical Field

[0001] This application relates to the field of photovoltaic module recycling, and more particularly to a method for recycling solar cells from waste photovoltaic modules, solar cells, and photovoltaic modules. Background Technology

[0002] Currently, the photovoltaic industry is developing rapidly. With a large number of photovoltaic modules reaching their 25-year service life and becoming obsolete, the disposal of these discarded modules has become a research hotspot in the field of resource recycling. As the core unit of photovoltaic modules, the recycling and reuse of photovoltaic cells is of great significance for reducing resource consumption and achieving sustainable development.

[0003] Traditional recycling of waste photovoltaic modules often employs a direct high-temperature pyrolysis process, which involves placing the entire module in a high-temperature environment to decompose the EVA film. However, this process has two major drawbacks: First, the fluorinated backsheet on the back of the module releases harmful fluorine gases at high temperatures, causing serious environmental pollution. Second, the large amount of gas generated by the thermal decomposition of EVA cannot be discharged in time, creating pressure expansion inside the module and causing the cells to break, significantly reducing the recycling rate of intact cells. Furthermore, subsequent sorting and purification of the broken cells is required, prolonging the recycling process. Summary of the Invention

[0004] The purpose of this application is to provide a method for recycling solar cells from waste photovoltaic modules.

[0005] The first aspect of this application discloses a method for recycling solar cells from waste photovoltaic modules, comprising the following steps: A milling machine is used to remove the backsheet from the used photovoltaic modules; Grooving and / or drilling holes on the back of the waste photovoltaic module after removing the back sheet; Start the tunnel furnace and preheat it to 300-500°C. Then put the waste photovoltaic modules into the tunnel furnace and heat them for 30-60 minutes. The waste photovoltaic modules are transported to a cooling zone and cooled to room temperature. After the encapsulating film decomposes and loses its adhesiveness, the solar cells are removed.

[0006] Optionally, a milling machine is used to remove the back plate, and the milling temperature is controlled not to exceed 190°C during the milling process; Preferably, water spraying is performed during the milling process; More preferably, dust extraction is performed during the milling process.

[0007] Optionally, gaps are formed between the cells on the waste photovoltaic module, and at least one groove is formed in the gaps; Preferably, the width of the trench is 2-3 mm, and the depth of the trench penetrates the encapsulation film on the front or back. Preferably, the trench includes a longitudinal groove extending in a first direction and a transverse groove extending in a second direction, the longitudinal groove and the transverse groove intersecting to form a grid-like trench.

[0008] Optionally, gaps are formed between the solar cells on the waste photovoltaic module, and multiple micropores are formed in the gaps; Preferably, the diameter of the micropores is 1-2 mm, the spacing between the micropores is 4-6 cm, and the depth of the micropores penetrates the encapsulation film on the front or back.

[0009] Alternatively, grooving can be performed using a cutting tool or laser, or drilling can be performed using a drill or laser; Preferably, a laser is used for grooving or drilling, wherein the wavelength of the laser is 1000-1100nm and the power of the laser is 50-80W.

[0010] Optionally, the tunnel furnace adopts a segmented temperature control mode, including a first preheating section, a main heating section, and a heat preservation section; wherein, the temperature of the main heating section is greater than the temperature of the heat preservation section, and the temperature of the heat preservation section is greater than the temperature of the preheating section; and / or, the waste photovoltaic modules are placed with their backs facing upwards in the tunnel furnace; Preferably, the temperature of the preheating section is 300-350℃; and / or, the temperature of the main heating section is 400-500℃; and / or, the temperature of the heat preservation section is 350-400℃.

[0011] Optionally, the cooling zone adopts a gradient cooling mode, which includes at least two cooling stages. The first stage reduces the temperature of the waste photovoltaic modules to below 150°C, and the second stage reduces the temperature of the waste photovoltaic modules to below 50°C. The cooling rate of the first stage is higher than that of the second stage. Preferably, the cooling rate in the first stage is 5-8℃ / min, and the cooling rate in the second stage is 1-3℃ / min.

[0012] Optionally, the battery cells are placed in an ultrasonic cleaning tank to clean them; Preferably, the battery cells are cleaned using deionized water in the ultrasonic cleaning tank; More preferably, the ultrasonic cleaning tank has a power of 90-120W; an ultrasonic frequency of 80-100kHz; and a cleaning time of 10-30min.

[0013] This application provides a complete method for recycling solar cells from waste photovoltaic modules. (1) No harmful gases are generated during the recycling process; (2) The recycling process is short and the cost is low; (3) The integrity rate of the recycled solar cells can be as high as 96% or more; (4) The grid lines, passivation layers and other structures of the recycled solar cells are not damaged and can be directly used for the preparation of new modules.

[0014] The second aspect of this application provides a battery cell prepared using the recycling method of the first aspect of this application.

[0015] A third aspect of this application provides a battery cell comprising the one provided in the second aspect of this application. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 A schematic flowchart of a method for recycling solar cells from waste photovoltaic modules according to this application is shown; Figure 2 A partial schematic diagram of one embodiment of the waste photovoltaic module with a grooved back side according to this application is shown; Figure 3 A schematic cross-sectional view of one embodiment of the waste photovoltaic module with a grooved back side according to this application is shown; Figure label: 10 - Solar cell; 101 - Gap between solar cells; 102 - Trench; 20 - Backside encapsulation film; 30 - Frontside encapsulation film; 40 - Frontside glass. Detailed Implementation

[0017] Embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0018] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise expressly specified. "Several" means one or more, unless otherwise expressly specified.

[0019] The first aspect of this application provides a method for recycling solar cells from waste photovoltaic modules, such as... Figure 1As shown, it includes the following steps: A milling machine is used to remove the backsheet from the used photovoltaic modules; In this step, the waste photovoltaic modules include photovoltaic panels formed by multiple cells connected in series and / or in parallel. Both the front and back of the panel are covered with an encapsulating film (usually EVA film). The front encapsulating film has a front glass layer, and the back encapsulating film has a backsheet layer. Waste photovoltaic modules are generally divided into two types: single-glass modules and double-glass modules. For single-glass modules, the back encapsulating film on the back of the waste photovoltaic module has a backsheet layer, such as a polyvinylidene fluoride (PVF) backsheet or a polyvinylidene fluoride (PVDF) backsheet. For double-glass modules, the back encapsulating film on the back of the waste photovoltaic module has a back glass layer. The method provided in this application is only applicable to single-glass modules. Grinding the backsheet of double-glass modules with a milling machine will cause the glass to break, resulting in the internal cells cracking.

[0020] Specifically, discarded photovoltaic modules include aluminum frames and junction boxes, which can be removed through simple mechanical disassembly, such as unscrewing the frame screws or cutting the junction box connection wires.

[0021] The backplate is removed using a milling machine. The milling machine can precisely control the milling depth so that the milling depth is exactly equal to the thickness of the backplate, thus avoiding damage to the underlying EVA film and battery cells.

[0022] Specifically, the milling machine can be equipped with a diamond milling cutter head. The waste photovoltaic modules are fixed on the worktable of the CNC milling machine, keeping the waste photovoltaic modules horizontal. The milling machine is started, and the back plate is removed by uniform feeding from the back side.

[0023] In one alternative approach, a milling machine is used to remove the backsheet, and the milling temperature is controlled to not exceed 190°C during the milling process. The milling machine can precisely control the milling depth so that the milling depth is exactly equal to the thickness of the backsheet, thereby avoiding damage to the underlying EVA film and battery cells, and controlling the temperature to not exceed 190°C; this prevents the backsheet from softening and becoming difficult to grind; in addition, keeping the temperature below 190°C also avoids the emission of fluorine-containing gases.

[0024] Preferably, water spraying is performed during the milling process to reduce the heat generated during milling and prevent the back plate from softening and becoming difficult to grind.

[0025] Preferably, dust extraction is performed during the milling process. This allows for the real-time collection of milling debris, preventing dust pollution of the environment.

[0026] Grooving and / or drilling holes on the back of the waste photovoltaic module after removing the back sheet; In this step, grooves and / or holes are made on the back of the waste photovoltaic modules after the backsheet has been removed; this avoids the accumulation of decomposition gases inside the waste photovoltaic modules during the subsequent thermal decomposition of the encapsulation film, which could cause the cells to break due to pressure shock.

[0027] In one alternative embodiment, gaps 101 are formed between the solar cells 10 on the waste photovoltaic module, and at least one groove 102 is formed in the gaps 101. Specifically, as shown... Figure 2 As shown, the solar cells of a waste photovoltaic module are composed of multiple solar cells 10, with gaps 101 between the solar cells 10; as Figure 3 As shown, the solar cell 10 is disposed between the back encapsulation film 20 and the front encapsulation film 30, and the front encapsulation film 30 is disposed on the front glass 40; a groove is cut along the gap 101 to form at least one groove 102. Cutting grooves in the gap between the solar cells can avoid the solar cell body and prevent damage to the solar cells during the grooving process, while providing an exhaust channel for the pyrolysis gas of the encapsulation film.

[0028] Preferably, the width of the groove 102 is controlled at 2-3 mm, and the depth of the groove 102 penetrates the encapsulation film on the front or back. When the groove 102 is slotted or perforated from the back, the depth of the groove 102 penetrates the encapsulation film 20 on the back. When the groove 102 is slotted or perforated from the front, the depth of the groove 102 penetrates the encapsulation film 30 on the front.

[0029] More preferably, such as Figure 2 As shown, the trench includes a longitudinal groove extending along a first direction and a transverse groove extending along a second direction, the longitudinal groove and the transverse groove intersecting to form a grid-like trench; the first direction and the second direction are perpendicular to each other.

[0030] In another alternative approach, gaps are formed between the cells of the waste photovoltaic module, and holes are punched in the gaps to form multiple micropores; specifically, holes are punched in the gaps between the cells of the waste photovoltaic module, the diameter of the micropores is controlled at 1-2 mm, the spacing between the micropores is 4-6 cm, and the depth also penetrates the encapsulation film layer.

[0031] Grooving can be performed using mechanical cutting tools, such as carbide inserts, which cut along a predetermined path; laser processing can also be used. Drilling can be performed using a drill or a laser. When using a laser for grooving or drilling, the wavelength of the laser is 1000-1100nm, and the power of the laser is 50-80W.

[0032] Understandably, grooving and drilling can be used in combination. For example, longitudinal grooves can be made on the back of the component, and microholes can be drilled to further enhance the gas discharge effect.

[0033] Start the tunnel furnace and preheat it to 300-500°C. Then put the waste photovoltaic modules into the tunnel furnace and heat them for 30-60 minutes. In this step, the grooved / drilled waste photovoltaic modules are placed on the conveyor belt of the tunnel furnace. Before conveying, the tunnel furnace is started and preheated to a set range, such as 300-500℃ (e.g., 300℃, 350℃, 400℃, 450℃, or 500℃). If the temperature is below 300℃, the EVA decomposition reaction is extremely slow or even does not occur; if the temperature is above 500℃, the decomposition is too rapid, causing a large amount of gas to be generated instantaneously, increasing the risk of cell breakage. The heating time of the waste photovoltaic modules in the tunnel furnace is controlled within 30-60 minutes (e.g., 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min) to ensure complete decomposition of the EVA film.

[0034] In one alternative embodiment, the waste photovoltaic modules are placed with their backs facing upwards in the tunnel furnace to facilitate the discharge of pyrolysis gases.

[0035] In one alternative approach, the tunnel furnace employs a segmented temperature control mode, comprising a first preheating section, a main heating section, and a heat preservation section; wherein the temperature of the main heating section is higher than the temperature of the heat preservation section, and the temperature of the heat preservation section is higher than the temperature of the preheating section; thereby, through segmented control, the encapsulating film is slowly softened in the preheating section to prevent sudden temperature rises that could cause module deformation; the main heating section enables rapid decomposition of the encapsulating film, improving recycling efficiency; and the heat preservation section ensures the decomposition of the encapsulating film, preventing localized undecomposed areas that could lead to difficulties in separating the battery cells.

[0036] Preferably, the temperature of the preheating section is 300-350℃; for example, it can be 300℃, 305℃, 310℃, 315℃, 320℃, 325℃, 330℃, 335℃, 340℃, 345℃ or 350℃.

[0037] The temperature of the main heating section is 400-500℃; for example, it can be 400℃, 405℃, 410℃, 415℃, 420℃, 425℃, 430℃, 435℃, 440℃, 445℃, 450℃, 455℃, 460℃, 465℃, 470℃, 475℃, 480℃, 485℃, 490℃, 495℃, or 500℃.

[0038] The temperature of the insulation section is 350-400℃; for example, it can be 350℃, 355℃, 360℃, 365℃, 370℃, 375℃, 380℃, 385℃, 390℃, 395℃ or 400℃.

[0039] The waste photovoltaic modules are transported to a cooling zone and cooled to room temperature. After the encapsulating film decomposes and loses its adhesiveness, the solar cells are removed.

[0040] In this step, the waste photovoltaic modules are heated in a tunnel furnace and then conveyed to a cooling zone to cool to room temperature. At this point, the EVA film has decomposed and lost its adhesive properties, and it no longer adheres to the front glass and solar cells, allowing for easy separation.

[0041] The cooling zone employs a gradient cooling mode, which includes at least two cooling stages. The first stage reduces the temperature of the waste photovoltaic modules to below 150°C, for example, to 150°C, 145°C, 140°C, 135°C, 130°C, 125°C, or 120°C. The second stage reduces the temperature of the waste photovoltaic modules to below 50°C, for example, to 50°C, 45°C, 40°C, 35°C, 30°C, 25°C, or 20°C. The cooling rate in the first stage is higher than that in the second stage. This rapid cooling at high temperatures improves production efficiency and shortens process time, while the slow cooling at low temperatures prevents thermal stress from causing microcracks or hidden cracks in the cells, thus protecting the integrity of the cells.

[0042] Preferably, the cooling rate of the first stage is 5-8℃ / min, for example, 5℃ / min, 6℃ / min, 7℃ / min, or 8℃ / min; the cooling rate of the second stage is 1-3℃ / min, for example, 1℃ / min, 2℃ / min, or 3℃ / min.

[0043] In one alternative approach, a vacuum suction cup is used to separate and remove the battery cell. The vacuum suction cup can achieve uniform force and avoid secondary damage to the battery cell.

[0044] In one alternative approach, the solar cells are placed in an ultrasonic cleaning tank for cleaning. When the solar cells are removed from discarded photovoltaic modules, their surfaces may have EVA decomposition residue and trace impurities. Cleaning the solar cells in an ultrasonic cleaning tank can remove these impurities.

[0045] Preferably, the battery cells are cleaned using deionized water in the ultrasonic cleaning tank; More preferably, the ultrasonic cleaning tank has a power of 90-120W and an ultrasonic frequency of 80-100kHz; the cleaning time is 10-30min.

[0046] The second aspect of this application provides a solar cell prepared using the recycling method of the first aspect of this application. This solar cell originates from spent photovoltaic modules, has a clean surface free of chemical corrosion, and its grid lines and passivation layer are undamaged. Its photoelectric conversion efficiency can retain more than 80% of the original efficiency. This solar cell can be directly used to manufacture new photovoltaic modules, achieving high-value recycling of resources.

[0047] The third aspect of this application provides a solar cell comprising the one provided in the second aspect of this application. This photovoltaic module is prepared from recycled solar cells, making it environmentally friendly and cost-effective.

[0048] The following describes in detail a method for recycling spent photovoltaic modules according to this application using several specific embodiments. It is important to understand that the following description is merely illustrative and not intended to limit the invention.

[0049] The waste photovoltaic modules used in Examples 1-4 and Comparative Example 1 are all single-glass modules, for reference. Figure 2 and Figure 3 As shown, the device includes a front glass, an encapsulating film, a solar panel, another encapsulating film, and a backsheet. The solar panel is made of 60 aluminum backsheet solar cells measuring 157mm × 157mm × 200μm (side length × side length × thickness). The solar panel includes two strings of 6 cells each, with a 2.5mm gap between the cells and a 3.5mm gap between the two strings.

[0050] The testing methods for the solar cells obtained using Examples 1-4 and Comparative Example 1 are as follows: (1) Appearance Defect Rate: Under a standard light source of 1000Lx, two inspectors performed a double inspection on the solar cells and recorded the number of solar cells with visible defects such as chipped edges, missing corners, and fragments. The appearance defect rate is calculated as follows: (1 - number of intact solar cells removed from the entire photovoltaic module / number of original solar cells in the entire photovoltaic module) × 100% (2) Electrical performance testing; The efficiency data of the solar cells were tested using a solar cell tester. The percentage of cell efficiency = the average efficiency data of the extracted cells / the original cell efficiency data recorded in the photovoltaic module × 100%. Example

[0051] First, a milling machine is used to remove the backsheet of the waste photovoltaic module. The waste photovoltaic module is fixed on the CNC milling machine table, a diamond milling cutter head is installed, and the milling depth is adjusted to 0.2mm. Water spraying is carried out during the milling process to control the temperature of the milling process to not exceed 190℃. After starting the negative pressure dust collection device, the milling is carried out. After 20 minutes, the backsheet is completely removed and all the debris is collected.

[0052] Carbide blades are used to cut grooves along the gaps between the cells on the back of the waste photovoltaic module. The grooves are 2mm wide and 0.6mm deep. The grooves include 9 longitudinal grooves extending in a first direction and 5 transverse grooves extending in a second direction. The longitudinal and transverse grooves intersect to form a grid-like groove. The longitudinal and transverse grooves penetrate the edge of the waste photovoltaic module.

[0053] Start the tunnel furnace and preheat it to 300°C. Then, transport the waste photovoltaic modules into the tunnel furnace, and then control the temperature at 450°C for 15 minutes. Finally, control the temperature at 350°C for 20 minutes.

[0054] The waste photovoltaic modules are cooled to room temperature after being removed from the furnace, and a gradient cooling mode is adopted. In the first stage, the temperature of the waste photovoltaic modules is reduced to 150℃, and in the second stage, the temperature of the waste photovoltaic modules is reduced to below 50℃. The cooling rate in the first stage is 5℃ / min, and the cooling rate in the second stage is 1℃ / min.

[0055] The battery cells were removed one by one using a vacuum suction cup, and an inspection for defects in appearance was performed. The complete battery cell was placed in an ultrasonic cleaning tank, cleaned with deionized water for 10 minutes, and its electrical performance was tested. Example

[0056] Compared with Example 1, Example 2 involves drilling holes in the gap area between the back cells of the waste photovoltaic module. The diameter of the microholes is 1.5 mm and the spacing between the microholes is 5 cm. The gap between the back cells of the waste photovoltaic module includes 9 gaps extending along the first direction and 5 gaps extending along the second direction. Drilling is performed in all gaps. Example

[0057] Compared with Example 1, Example 3 does not use a gradient cooling mode, but directly uses a cooling rate of 1℃ / min to reduce the temperature of the waste photovoltaic modules to room temperature. Example

[0058] In Example 4, the temperature in the tunnel furnace remained unchanged compared to Example 1. First, start the tunnel furnace and preheat it to 350°C. Then, transport the waste photovoltaic modules into the tunnel furnace and keep the temperature at 350°C for 35 minutes.

[0059] Compared with Example 1, Comparative Example 1 did not undergo grooving treatment; its specific process is as follows: The waste photovoltaic modules are single-glass modules, including front glass, encapsulating film, solar panel, encapsulating film, and backsheet. The solar panel is made of 60 aluminum backsheet solar cells with dimensions of 157mm × 157mm × 200μm (side length × side length × thickness). The solar panel includes two strings of 6 cells × 5 cells, with a gap of 2.5mm between the cells and a gap of 3.5mm between the two strings.

[0060] First, a milling machine is used to remove the backsheet of the waste photovoltaic module. The waste photovoltaic module is fixed on the CNC milling machine table, a diamond milling cutter head is installed, and the milling depth is adjusted to 0.2mm. Water spraying is carried out during the milling process to control the temperature of the milling process to not exceed 190℃. After starting the negative pressure dust collection device, the milling is carried out. After 20 minutes, the backsheet is completely removed and all the debris is collected.

[0061] Start the tunnel furnace, preheat the furnace temperature to 400℃, and adjust the conveyor belt speed so that the heating time of the waste photovoltaic modules in the furnace is 35 minutes. After the waste photovoltaic modules are cooled to room temperature after being taken out of the furnace, the cells are removed one by one using a vacuum suction cup; and they are then inspected for chipping, fragmentation, etc. The complete battery cell was placed in an ultrasonic cleaning tank, cleaned with deionized water for 10 minutes, and its electrical performance was tested.

[0062] Table 1 shows the appearance defect rate and battery cell efficiency percentage of the extracted cells from Examples 1-4 and Comparative Example 1. As can be seen from the table, (1) compared with Comparative Example 1, the appearance defect rate of Examples 1-4 was significantly improved, and the battery efficiency retention rate was as high as 80% or more; (2) compared with Example 1, Example 2 adopted a perforation scheme, which was slightly less effective than the grid groove but significantly better than the comparative example, indicating that perforation can also effectively expel gas. (3) compared with Example 1, Example 3 did not use gradient cooling, and the appearance defect rate increased to 11.7%, while the efficiency retention rate decreased to 78.3%, indicating that gradient cooling may play an important role in preventing thermal stress cracks. (4) compared with Example 1, Example 4 did not use segmented temperature control, and the appearance defect rate was 8.3%, while the efficiency retention rate was 81.6%, indicating that segmented temperature control helps to control the decomposition rate.

[0063] Table 1 shows the appearance defect rate and cell efficiency percentage of the extracted solar cells from Examples 1-4 and Comparative Example 1.

[0064] Although this application has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings, disclosure, and appended claims, will understand and implement other variations of the disclosed embodiments in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple instances. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0065] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of this application as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from the spirit and scope of this application. Thus, if such modifications and modifications of this application fall within the scope of the claims of this application and their equivalents, this application is also intended to include such modifications and modifications.

Claims

1. A method for recycling solar cells from waste photovoltaic modules, characterized in that, Includes the following steps: A milling machine is used to remove the backsheet from the used photovoltaic modules; Grooving and / or drilling holes on the back of the waste photovoltaic module after removing the back sheet; Start the tunnel furnace and preheat it to 300-500°C. Then put the waste photovoltaic modules into the tunnel furnace and heat them for 30-60 minutes. The waste photovoltaic modules are transported to a cooling zone and cooled to room temperature. Once the encapsulating film loses its adhesiveness, the solar cells are removed.

2. The recycling method according to claim 1, characterized in that, The back plate is removed using a milling machine, and the milling temperature is controlled to not exceed 190°C during the milling process; Preferably, water spraying is performed during the milling process; More preferably, dust extraction is performed during the milling process.

3. The recycling method according to claim 1, characterized in that, The waste photovoltaic modules have gaps between the cells, and at least one groove is formed in the gaps. Preferably, the width of the trench is 2-3 mm, and the depth of the trench penetrates the encapsulation film on the front or back. Preferably, the trench includes a longitudinal groove extending along a first direction and a transverse groove extending along a second direction, the longitudinal groove and the transverse groove intersecting to form a grid-like trench; the first direction and the second direction are perpendicular to each other.

4. The recycling method according to claim 1, characterized in that, There are gaps between the solar cells on the waste photovoltaic module, and holes are punched in the gaps to form multiple micropores. Preferably, the diameter of the micropores is 1-2 mm, the spacing between the micropores is 4-6 cm, and the depth of the micropores penetrates the encapsulation film on the front or back.

5. The recycling method according to claim 1, characterized in that, Grooving is done using a cutting tool or laser, or drilling is done using a drill or laser; Preferably, a laser is used for grooving or drilling, wherein the wavelength of the laser is 1000-1100nm and the power of the laser is 50-80W.

6. The recycling method according to claim 1, characterized in that, The tunnel furnace adopts a segmented temperature control mode, including a first preheating section, a main heating section, and a heat preservation section; wherein, the temperature of the main heating section is greater than the temperature of the heat preservation section, and the temperature of the heat preservation section is greater than the temperature of the preheating section; and / or, the waste photovoltaic modules are placed with their backs facing upwards in the tunnel furnace; Preferably, the temperature of the preheating section is 300-350℃; and / or, the temperature of the main heating section is 400-500℃; and / or, the temperature of the heat preservation section is 350-400℃.

7. The recycling method according to claim 1, characterized in that, The cooling zone adopts a gradient cooling mode, which includes at least two cooling stages. The first stage reduces the temperature of the waste photovoltaic modules to below 150°C, and the second stage reduces the temperature of the waste photovoltaic modules to below 50°C. The cooling rate of the first stage is higher than that of the second stage. Preferably, the cooling rate in the first stage is 5-8℃ / min, and the cooling rate in the second stage is 1-3℃ / min.

8. The recycling method according to claim 1, characterized in that, The battery cells are placed in an ultrasonic cleaning tank for cleaning. Preferably, the battery cells are cleaned using deionized water in the ultrasonic cleaning tank; More preferably, the ultrasonic cleaning tank has a power of 90-120W, an ultrasonic frequency of 80-100kHz, and a cleaning time of 10-30min.

9. A type of battery cell, characterized in that, It is prepared using the recycling method described in any one of claims 1-8.

10. A photovoltaic module, characterized in that, It includes the battery cell as described in claim 9.

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