Cell, photovoltaic module, and packaging method for cell

Abstract

A cell, a photovoltaic module, and a packaging method for a cell. The cell is a back-contact solar cell, and since a light receiving face of the cell is covered with a protection layer, the light receiving face of the cell can be prevented from being scratched due to the stacking and transportation of cells; and isolation paper does not need to be placed between two adjacent cells, thus reducing a fault rate of a production line.

Description

A cell, a photovoltaic module and a cell packaging method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the Patent Office of China on July 4, 2023, with application number 202310814645.8, entitled “A method for packaging battery cells, battery cells and photovoltaic modules”, and the Chinese patent application filed with the Patent Office of China on July 4, 2023, with application number 202321742101.7, entitled “A battery cell and photovoltaic module”. The entire contents of the aforementioned two patent applications are incorporated into this application by reference. Technical Field

[0003] The present application relates to the technical field of solar cells, and in particular to a cell, a photovoltaic module, and a method for packaging a cell. Background Art

[0004] An IBC cell (also known as an interdigitated back contact cell) is a cell in which both the emitter electrode and the base electrode are located on the back side. Currently, when storing and transporting back-contact solar cells, multiple back-contact solar cells are stacked directly. Since the back electrode of one back-contact solar cell is in direct contact with the light-receiving surface of an adjacent back-contact solar cell, the light-receiving surface is easily scratched by friction, thereby reducing the back-contact solar cell's absorption of light, and further causing a decline in the cell's photoelectric conversion performance.

[0005] In the prior art, to reduce the possibility of scratches on the light-receiving surface of battery cells during stacking and transportation, operators often place separator paper between two adjacent battery cells. However, the inventors have discovered that this approach has at least the following problems:

[0006] The release paper is difficult to remove and can easily be brought into the production line, causing malfunctions.

[0007] The utilization rate of release paper is low and the consumption is high, which leads to increased costs.

[0008] Summary of the Invention

[0009] The present application provides a cell, a photovoltaic module, and a cell packaging method to solve or at least partially solve the problems existing in the prior art.

[0010] The technical solution of this application is as follows:

[0011] The present application provides a cell, which is a back-contact solar cell. A protective layer is provided on the light-receiving surface of the cell, and the transmittance of the protective layer is greater than a transmittance threshold; the heat-resistant temperature of the protective layer is greater than or equal to the heat-resistant temperature threshold.

[0012] Preferably, an adhesive layer is provided between the protective layer and the light-receiving surface of the cell; the first surface of the protective layer is bonded to the first surface of the adhesive layer, and the second surface of the adhesive layer is bonded to the light-receiving surface of the cell.

[0013] Preferably, the adhesive layer includes a plurality of adhesive portions, and the adhesive portions are evenly or unevenly distributed over the entire or partial area of ​​the light receiving surface.

[0014] Preferably, the thickness of the adhesive layer is in a range of 5 microns to 10 microns.

[0015] Preferably, the material of the protective layer is one of polyethylene terephthalate material and photosensitive adhesive material.

[0016] Preferably, when the material of the protective layer is a photosensitive adhesive material, the protective layer is a protective layer formed by the cured photosensitive adhesive material; and / or the adhesive layer is an ethylene vinyl acetate copolymer material.

[0017] Preferably, at least one side of the protective layer is a frosted surface; the thickness of the protective layer is within a thickness range, the thickness range is 30 microns to 60 microns; the roughness of the first side of the protective layer is in a range of 0.4 mm to 1.0 mm; and / or: the roughness of the second side of the protective layer is in a range of 0.4 mm to 1.0 mm.

[0018] Preferably, the hardness of the protective layer is within a hardness range of Shore D55 to Shore D85; the transmittance threshold is 95%; and / or the heat resistance temperature threshold is 160°C or 200°C.

[0019] The present application also provides a photovoltaic module, comprising the above-mentioned cell.

[0020] The present application also provides a method for packaging a battery cell, wherein the battery cell is a back-contact solar cell, and the method comprises: providing a protective layer on the light-receiving surface of the battery cell, wherein the transmittance of the protective layer is greater than a transmittance threshold; and the heat-resistant temperature of the protective layer is greater than or equal to the heat-resistant temperature threshold.

[0021] Preferably, the protective layer is provided on the light-receiving surface of the battery cell, comprising: forming a covering layer of a polymer material on the light-receiving surface of the battery cell, the transmittance of the polymer material being greater than a transmittance threshold, and the heat resistance temperature of the polymer material being greater than or equal to a heat resistance temperature threshold; and curing the covering layer to form a protective layer on the light-receiving surface of the battery cell.

[0022] Preferably, the formation of a polymer material covering layer on the light-receiving surface of the battery cell includes: heating the polymer material to a first preset temperature to melt it into a liquid state to form a spray coating, and the first preset temperature is greater than the heat-resistant temperature; spraying the spray coating on the light-receiving surface according to a first preset pressure to form the covering layer; wherein the heat-resistant temperature is 255°C; and the first preset pressure ranges from 0.4 kgf to 0.6 kgf.

[0023] Preferably, curing the covering layer to form a protective layer for the light-receiving surface of the battery cell includes: curing the covering layer at a second preset temperature based on a first curing time to form the protective layer; wherein the first curing time ranges from 10 seconds to 15 seconds, and the second preset temperature ranges from 5 degrees to 15 degrees.

[0024] Preferably, the spray coating material is sprayed on the light receiving surface according to a first preset pressure to form the covering layer, comprising: spraying the spray coating material on the light receiving surface according to a first preset pressure, and forming the spray coating material on the light receiving surface into the covering layer when the thickness of the spray coating material on the light receiving surface is within a thickness range; wherein the thickness range is 30 microns to 60 microns.

[0025] Preferably, the polymer material is a photosensitive adhesive material; the polymer material covering layer is formed on the light-receiving surface of the battery cell, including: spraying the photosensitive adhesive material on the light-receiving surface to form the covering layer according to a second preset pressure; the second preset pressure ranges from 0.4 kgf to 0.6 kgf; or: printing the photosensitive adhesive material on the light-receiving surface by screen printing to form the covering layer according to a third preset pressure; the third preset pressure ranges from 50 Newtons to 60 Newtons.

[0026] Preferably, curing the covering layer to form a protective layer for the light-receiving surface of the cell includes: curing the covering layer under ultraviolet ray irradiation to form the protective layer based on a second curing time; the second curing time ranges from 2 seconds to 3 seconds.

[0027] Preferably, curing the covering layer to form a protective layer for the light-receiving surface of the battery cell includes: curing the covering layer, and forming the covering layer into the protective layer when the hardness of the surface of the covering layer formed into a solid state is within a hardness range and the thickness of the covering layer formed into a solid state is within a thickness range; or curing the covering layer, and determining the roughness of the surface of the covering layer formed into a solid state when the hardness of the surface of the covering layer formed into a solid state is determined to be within a hardness range and the thickness of the covering layer formed into a solid state is within a thickness range; forming the covering layer into the protective layer when the roughness of the surface of the covering layer formed into a solid state is within a roughness range; wherein the hardness range is Shore hardness D55 to Shore hardness D85; the thickness range is 30 microns to 60 microns; and the roughness range is 0.4 mm to 1 mm.

[0028] Preferably, the protective layer is a film, and the protective layer is a polyethylene terephthalate material or a photosensitive adhesive material; the step of setting the protective layer on the light-receiving surface of the battery cell includes: obtaining the protective layer and forming an adhesive layer on the protective layer; and setting the protective layer on the light-receiving surface of the battery cell through the adhesive layer.

[0029] Preferably, forming the adhesive layer on the protective layer includes: spraying an adhesive on the protective layer to form an adhesive covering layer; heating the adhesive covering layer at a third preset temperature based on a preset time to form the adhesive layer; wherein the preset time ranges from 1 second to 3 seconds, and the third preset temperature ranges from 90°C to 120°C.

[0030] Preferably, the step of arranging the protective layer on the light-receiving surface of the battery cell through the adhesive layer includes: placing the protective layer on the light-receiving surface of the battery cell through the adhesive layer, so that the adhesive layer is arranged between the protective layer and the light-receiving surface of the battery cell; based on the pressing pressure, pressing the protective layer so that the protective layer is adhered to the light-receiving surface of the battery cell through the adhesive layer; wherein the pressing pressure ranges from 30 Newtons to 50 Newtons.

[0031] The present application provides a battery cell, which is a back-contact solar cell. Since the light-receiving surface of the battery cell is covered with a protective layer, the light-receiving surface of the battery cell can be prevented from being scratched due to the stacking and transportation of the battery cells, and there is no need to place isolation paper between two adjacent battery cells, thereby reducing the failure rate of the production line. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are provided to facilitate a better understanding of the present application and do not constitute an undue limitation on the present application.

[0033] FIG1 is a partial side view of a battery cell provided by an embodiment of the present invention;

[0034] FIG2 is a schematic diagram of a battery cell provided by an embodiment of the present invention;

[0035] FIG3 is a schematic structural diagram of a battery cell provided in an embodiment of the present application;

[0036] FIG4 is a schematic structural diagram of a photovoltaic module provided by an embodiment of the present invention;

[0037] FIG5 is a flowchart of a method for packaging a battery cell according to an embodiment of the present application;

[0038] FIG6 is a flowchart showing the specific steps of a battery cell packaging method provided in an embodiment of the present application;

[0039] FIG7 is a flowchart showing the specific steps of another battery cell packaging method provided in an embodiment of the present application.

[0040] Figure numerals: 10 - battery cell; 11 - protective layer; 111 - first side of protective layer; 112 - second side of protective layer; 12 - adhesive layer; 121 - first side of adhesive layer; 122 - second side of adhesive layer; 13 - light-receiving surface; 14 - backlight surface; 15 - electrode; 21 - glass layer; 22 - first adhesive layer; 23 - second adhesive layer; 24 - back plate; 25 - outer frame; 26 - junction box. Specific embodiments

[0041] The following description of exemplary embodiments of the present application includes various details in some embodiments to facilitate understanding, which should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0042] 1 , the present application provides a cell 10 , which is a back-contact solar cell. A light-receiving surface 13 of the cell 10 is provided with a protective layer 11 , wherein the transmittance of the protective layer 11 is greater than a transmittance threshold; and the heat-resistant temperature of the protective layer 11 is greater than or equal to the heat-resistant temperature threshold.

[0043] Optionally, in some embodiments, the light-receiving surface 13 of the battery cell 10 is sequentially provided with an adhesive layer 12 and a protective layer 11; the transmittance of the protective layer 11 is greater than the transmittance threshold; the heat resistance temperature of the protective layer 11 is greater than or equal to the heat resistance temperature threshold; the first surface 111 of the protective layer 11 is bonded to the first surface 121 of the adhesive layer 12, and the second surface 122 of the adhesive layer 12 is bonded to the light-receiving surface 13 of the battery cell 10.

[0044] It should be noted that, referring to FIG4 , a photovoltaic module (solar cell module) using back-contact solar cells comprises, in order from the front to the back, a glass layer 21, a first adhesive layer 22, a series connection of cells 10, a second adhesive layer 23, a back sheet 24, and an outer frame 25. The glass layer 21 is generally tempered glass, which has good light transmittance and high hardness and can adapt to large temperature differences between day and night and adverse weather conditions. It is used to cover the cells 10 to protect them. The material of the first adhesive layer 22 and the second adhesive layer 23 is generally EVA (Ethylene Vinyl Acetate Copolymer (ethylene vinyl acetate copolymer) material, a first adhesive layer 22 is used to bond the cell 10 to the glass, and a second adhesive layer 23 is used to bond the cell 10 to the backsheet 24. The series group of cells 10 includes multiple cells 10. The cell 10 is a back-contact solar cell, which is a core component of a photovoltaic module used for solar power generation. The backsheet 24 is generally a TPT backsheet 24, which is composed of a three-layer film of PVF (polyvinyl-fluoride), PET (polyethylene glycol terephthalate), and PVF. The backsheet 24 has sealing, insulation, waterproofing, and aging resistance, which can protect the cell 10 and thus extend the service life of the photovoltaic module. The outer frame 25 is generally an aluminum alloy outer frame 25. The aluminum alloy outer frame 25 has good strength and corrosion resistance, and can support and protect the cell 10.

[0045] The photovoltaic module also includes a junction box 26 mounted on the aluminum alloy outer frame 25. This box protects the entire power generation system of the cells 10 and provides a seal and waterproofing effect for the photovoltaic module's lead wires. Furthermore, if a cell 10 short-circuits, the junction box 26 automatically disconnects the series connection of the short-circuited cell 10.

[0046] The production process of photovoltaic modules using back-contact solar cells includes: (1) battery testing, that is, classifying the cells 10 by testing the output parameters (current and voltage) of the cells 10 so as to group cells 10 with the same or similar performance; (2) transportation, that is, stacking the cells 10 and transporting them to the subsequent production line of the photovoltaic modules; (3) back-side green glue and gray glue printing, that is, printing the back-side green glue and gray glue on the electrodes 15 of the backlight surface 14 of the cells 10; (4) back-side series welding, that is, welding multiple cells 10 in series to form a series group of cells 10; (5) lamination, that is, laminating the glass layer 21, the first glue layer 22, the series group of cells 10, the second glue layer 23, and the back plate 24 in order. (6) Lamination, that is, placing the laid glass layer 21, the first adhesive layer 22, the series group of battery cells 10, the second adhesive layer 23, and the back plate 24 into a laminator, extracting the air in the assembly by vacuuming, and then heating to melt the first adhesive layer 22 and the second adhesive layer 23, and bonding the glass layer 21, the series group of battery cells 10, and the back plate 24 together to form an initial photovoltaic assembly. Finally, after cooling, the initial photovoltaic assembly is taken out, wherein the protective layer 11 of the battery cell 10, the first adhesive layer 22, and the glass layer 21 are fused into one interface to meet the transmittance requirement. There is no need to remove the protective layer, thereby improving production efficiency; (7) Photovoltaic assembly testing, that is, mainly testing the power of the photovoltaic assembly; (8) Assembly, that is, installing the outer frame 25, connecting the junction box 26, etc.

[0047] From the perspective of the type of cell material, the cell 10 provided in the embodiment of the present application is generally a monocrystalline silicon solar cell, and the photoelectric conversion efficiency of a monocrystalline silicon solar cell can reach 28.7%. In addition, the cell 10 provided in the embodiment of the present application can also be a heterojunction solar cell, and the photoelectric conversion efficiency of a heterojunction solar cell can reach 29.4%.

[0048] 2 , the cell 10 provided in the embodiment of the present application further includes a backlight surface 14 , on which electrodes 15 are provided. The types of electrodes 15 include positive electrodes and negative electrodes.

[0049] In the embodiment of the present application, since the light-receiving surface 13 of the battery cell 10 is covered with the protective layer 11, it is possible to prevent the light-receiving surface 13 of the battery cell 10 from being scratched due to the stacking and transportation of the battery cell 10, and there is no need to place isolation paper between two adjacent battery cells 10, thereby reducing the failure rate of the production line and solving the problem in the prior art that, during the production process of the photovoltaic module, isolation paper is placed between two adjacent battery cells 10 to prevent the light-receiving surface 13 of the battery cell 10 from being scratched due to the stacking and transportation of the battery cell 10, resulting in the isolation paper being brought into the production line and causing failures; in addition, during the lamination process of the photovoltaic module, the protective layer is fused with the glue layer and the glass to form a complete interface, which meets the transmittance requirements, does not need to remove the protective layer, and improves production efficiency.

[0050] Specifically, in some embodiments, the bonding layer 12 is an adhesive, such as an adhesive made of EVA material; the protective layer 11 is a film, and there are no bubbles inside the protective layer 11.

[0051] The adhesive for EVA materials is EVA composite adhesive, a type of glue whose main ingredients are thermoplastic styrene-butadiene rubber, rosin-modified resin, petroleum resin, and solvent. EVA composite adhesive offers excellent bonding properties, a long aging time, and requires no water treatment. It can be applied in a single application, making it easier to use and more efficient. The cured product bonded with EVA composite adhesive is exceptionally flexible, able to withstand severe drops and falls without peeling, providing excellent cushioning properties. EVA composite adhesive also has a low odor, meeting environmental and health standards. Furthermore, EVA composite adhesive exhibits high strength, transparency, and initial tack.

[0052] In the embodiment of the present application, the adhesive layer of the EVA composite adhesive can make the adhesion between the protective layer and the light-receiving surface of the battery cell more firm.

[0053] It should be noted that the first surface 121 and the second surface of the adhesive layer 12 are both planes, and the shape of the second surface 122 of the adhesive layer 12 is the same as the shape of the first surface 121 of the adhesive layer 12; the first surface 111 and the second surface 112 of the protective layer 11 are both planes, and the shape of the first surface 111 of the protective layer 11 is the same as the shape of the second surface 112 of the protective layer 11.

[0054] Optionally, in some embodiments, at least one side of the protective layer 11 is a frosted surface.

[0055] In the embodiment of the present application, since at least one side of the protective layer 11 is a frosted surface, the interface formed by the frosted surface in contact with other surfaces reduces the degree of specular reflection of light and improves the light transmittance.

[0056] Optionally, in some embodiments, both the first surface 111 and the second surface of the protective layer 11 are frosted surfaces.

[0057] In the embodiment of the present application, since the first surface 111 of the protective layer 11 is bonded to the first surface 121 of the adhesive layer 12, and the first surface 111 of the protective layer 11 is a frosted surface, the interface formed by the first surface 111 of the protective layer 11 and the first surface 121 of the adhesive layer 12 reduces the degree of specular reflection of light, thereby improving light transmittance. During the lamination process of the photovoltaic module production process, a first adhesive layer 22 of an EVA material adhesive is provided on the protective layer 11 of the cell 10 to bond the cell 10 to the glass plate. Since the second surface 112 of the protective layer 11 is in contact with the first adhesive layer 22, and the second surface 112 of the protective layer 11 is a frosted surface, the interface formed by the contact between the second surface 112 of the protective layer 11 and the first adhesive layer 22 reduces the degree of specular reflection of light, thereby improving light transmittance.

[0058] It should be noted that the entire first surface 111 of the protective layer 11 is a frosted surface; and the entire second surface 112 of the protective layer 11 is a frosted surface.

[0059] Optionally, in some embodiments, the roughness of the first surface 111 of the protective layer 11 is in a range of 0.4 mm to 1.0 mm; and / or the roughness of the second surface 112 of the protective layer 11 is in a range of 0.4 mm to 1.0 mm.

[0060] In the embodiment of the present application, since the roughness of the first surface 111 of the protective layer 11 ranges from 0.4 mm to 1.0 mm, the interface formed by the first surface 111 of the protective layer 11 and the first surface 121 of the adhesive layer 12 can reduce the degree of specular reflection of light, thereby improving light transmittance. During the lamination process of the photovoltaic module production process, a first adhesive layer 22 of an EVA material adhesive is provided on the protective layer 11 of the cell 10 to bond the cell 10 to the glass plate. During the lamination process of the photovoltaic module, the second surface 112 is filled with liquid EVA in contact with the second surface 112, ultimately forming a complete interface between the protective layer 11, the first adhesive layer 22 of the EVA, and the glass layer 21. Since the second surface 112 of the protective layer 11 is a frosted surface, the contact surface with the first adhesive layer of the EVA can be increased during the lamination process of the photovoltaic module, making the protective layer more firmly bonded to the glass.

[0061] Specifically, in some embodiments, the roughness of the first surface 111 of the protective layer 11 can be 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, etc.; the roughness of the second surface 112 of the protective layer 11 can be 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, etc.

[0062] Optionally, in some embodiments, the protective layer 11 covers the entire light-receiving surface 13 of the cell 10 .

[0063] In the embodiment of the present application, since the protective layer 11 covers the entire light-receiving surface 13 of the battery cell 10, the entire light-receiving surface 13 of the battery cell 10 can be protected, reducing the possibility of the light-receiving surface 13 of the battery cell 10 being scratched due to the stacking and transportation of the battery cell 10.

[0064] It should be noted that the shape of the second surface 112 of the protection layer 11 is the same as the shape of the light-receiving surface 13 of the cell 10 , so that the protection layer 11 covers the entire light-receiving surface 13 of the cell 10 .

[0065] Optionally, in some embodiments, the adhesive layer 12 includes a plurality of adhesive portions, and the adhesive portions are evenly or unevenly distributed over the entire or partial area of ​​the light receiving surface 13 .

[0066] In the embodiment of the present application, since the adhesive layer 12 includes multiple adhesive parts, the adhesive parts are evenly distributed in the entire or partial area of ​​the light-receiving surface 13, which can ensure the balance of the adhesive force between the protective layer 11 and the light-receiving surface 13, thereby improving the tightness of the adhesion between the protective layer 11 and the light-receiving surface 13.

[0067] It should be noted that the first surface 121 of the adhesive layer 12 includes the first surfaces of the plurality of adhesive portions; and the second surface 122 of the adhesive layer 12 includes the second surfaces of the plurality of adhesive portions.

[0068] Specifically, in some embodiments, the shape of each bonding portion may be the same or different, and the bonding portion may be rectangular, circular, triangular, or other shapes; the number of bonding portions may be 1, 2, 3, 4, or the like.

[0069] For example, when the light-receiving surface 13 of the battery cell 10 is rectangular, the adhesive layer 12 may include one rectangular adhesive portion, which is located in the central area of ​​the light-receiving surface 13, that is, the geometric center of the second surface of the adhesive portion coincides with the geometric center of the light-receiving surface 13, and each side of the second surface of the adhesive portion is parallel to the corresponding side of the light-receiving surface 13; the adhesive layer 12 may include two identical adhesive portions in a rectangular shape, and the two adhesive portions are symmetrically distributed with respect to the center line of the light-receiving surface 13; the adhesive layer 12 may include three identical adhesive portions in a rectangular shape, of which two adhesive portions are symmetrically distributed with respect to the center line of the light-receiving surface 13, the geometric center of the second surface of the other adhesive portion coincides with the geometric center of the light-receiving surface 13, and one side of the second surface of the other adhesive portion is parallel to the center line of the light-receiving surface 13; the adhesive layer 12 may include four identical adhesive portions in a rectangular shape, and the four adhesive portions are respectively located in the four corner areas of the light-receiving surface 13.

[0070] In other embodiments, the adhesive layer 12 includes N×M adhesive portions, which are evenly distributed in an array on the light-receiving surface 13 of the solar cell 10, where N is the number of adhesive portions in a first direction of the array, M is the number of adhesive portions in a second direction of the array, and the angle between the first and second directions is 90 degrees. Each adhesive portion can have the same shape, and can be rectangular, circular, triangular, or other shapes.

[0071] For example, when the light-receiving surface 13 of the battery cell 10 is rectangular, the adhesive layer 12 includes 20×30 circular adhesive portions, that is, the 20×30 circular adhesive portions are arranged in a uniform array on the light-receiving surface 13, and each row of the array along the first side of the light-receiving surface 13 has 20 adhesive portions, and each column of the array along the second side of the light-receiving surface 13 has 30 adhesive portions, and the angle between the first direction and the second direction is 90 degrees.

[0072] When the second surface 122 of the adhesive layer 12 (i.e., the plane formed by the second surfaces of all the adhesive parts) has the same shape as the light-receiving surface 13 of the battery cell 10, the adhesive parts are evenly distributed over the entire area of ​​the light-receiving surface 13; when the area of ​​the second surface 122 of the adhesive layer 12 (i.e., the plane formed by the second surfaces of all the adhesive parts) is smaller than the area of ​​the light-receiving surface 13 of the battery cell 10, the adhesive parts are evenly distributed over a partial area of ​​the light-receiving surface 13.

[0073] Optionally, in some embodiments, the adhesive layer 12 covers the entire light-receiving surface 13 of the cell 10 .

[0074] It should be noted that when the adhesive layer 12 covers the entire light-receiving surface 13 of the cell 10 , the shape of the first surface 111 of the protective layer 11 is the same as the shape of the first surface 121 of the adhesive layer 12 .

[0075] In the embodiment of the present application, since the adhesive layer 12 covers the entire light-receiving surface 13 of the battery cell 10, it can ensure that the entire first surface of the protective layer 11 is bonded to the entire light-receiving surface 13 of the battery cell 10, thereby improving the firmness of the bond between the first surface 111 of the protective layer 11 and the light-receiving surface 13 of the battery cell 10. At the same time, the appearance and texture of the light-receiving surface 13 of the battery cell 10 are uniform, thereby improving the aesthetics.

[0076] Optionally, in some embodiments, the thickness of the protective layer 11 ranges from 30 microns to 60 microns.

[0077] In the embodiment of the present application, since the thickness of the protective layer 11 ranges from 30 micrometers to 60 micrometers, the protective layer 11 is thinned, thereby meeting the requirement of thinning the battery cell 10 .

[0078] Specifically, in some embodiments, the thickness of the protective layer 11 can be 30 micrometers, 35 micrometers, 40 micrometers, 45 micrometers, 50 micrometers, 55 micrometers, 60 micrometers, etc.

[0079] Optionally, in some embodiments, the thickness of the adhesive layer 12 ranges from 5 microns to 10 microns.

[0080] In the embodiment of the present application, since the thickness of the adhesive layer 12 is in the range of 5 micrometers to 10 micrometers, the adhesive layer 12 is thinned, thereby meeting the requirement of thinning the battery cell 10 .

[0081] Specifically, in some embodiments, the thickness of the adhesive layer 12 may be 5 micrometers, 6 micrometers, 7 micrometers, 8 micrometers, 9 micrometers, or 10 micrometers.

[0082] Optionally, in some embodiments, the transmittance threshold is 95%.

[0083] In the embodiment of the present application, since the transmittance of the protective layer 11 is greater than the transmittance threshold, and the transmittance threshold is 95%, that is, the transmittance of the protective layer 11 is greater than 95%, the protective layer 11 has good transmittance, which meets the battery cell 10's requirement for good transmittance.

[0084] Specifically, in some embodiments, the light transmittance of the protective layer 11 may be 96%, 97%, 98%, 99%, etc.

[0085] Optionally, in some embodiments, the material of the protective layer 11 includes one of a polyethylene terephthalate material and a photosensitive adhesive material; and / or the adhesive layer is an ethylene vinyl acetate copolymer material.

[0086] Optionally, in some embodiments, the heat resistance temperature threshold is 160°C.

[0087] Because protective layers formed from materials with low melting points (e.g., EVA with a melting point between 60°C and 110°C) are prone to melting during the production of photovoltaic modules, causing the cells to stick to production equipment, affecting the normal production of photovoltaic modules. In the embodiment of the present application, the heat-resistant temperature of the protective layer 11 is greater than the heat-resistant temperature threshold, that is, the heat-resistant temperature of the protective layer 11 (i.e., the melting point of the protective layer 11) is greater than the heat-resistant temperature threshold (160°C), so that the protective layer 11 has good thermal stability and does not melt during the production of photovoltaic modules, thereby ensuring the normal production of photovoltaic modules.

[0088] Specifically, in some embodiments, the heat-resistant temperature of the protective layer 11 may be 250° C. (for example, the melting point of the protective layer of PET material is in the range of 250° C. to 255° C.).

[0089] Optionally, in some embodiments, the material of the protective layer 11 includes one of polyethylene terephthalate material and photosensitive adhesive material. When the material of the protective layer is photosensitive adhesive material, the protective layer is a protective layer formed by the cured photosensitive adhesive material; and / or, the adhesive layer is ethylene vinyl acetate copolymer material.

[0090] In the embodiment of the present application, the material of the protective layer 11 includes one of polyethylene glycol terephthalate (PET) and photosensitive adhesive (UV adhesive, UV stands for ultraviolet) materials. The heat resistance temperature of the polyethylene terephthalate material is in the range of 250°C to 255°C (for example, 255°C), and the heat resistance temperature of the photosensitive adhesive material is 160°C. The heat resistance temperature of both materials is greater than or equal to 160°C, which can prevent the protective layer from melting during the production process of the photovoltaic module, causing the solar cells to stick to the production equipment and affecting the normal production of the photovoltaic module. Both materials have a transmittance greater than 95% and a reliability of greater than 25 years, which can meet the performance requirements of the light transmittance and reliability of the solar cell 10. In addition, the protective layer 11 can also be made of other materials with a transmittance greater than 95%, a heat resistance temperature greater than or equal to 160°C, and a reliability of greater than 25 years. The adhesive layer is made of ethylene vinyl acetate copolymer material, which ensures a stronger bond between the protective layer and the light-receiving surface of the solar cell.

[0091] It should be noted that polyethylene terephthalate (PET) is a milky white or light yellow, highly crystalline polymer with a smooth, glossy surface. It exhibits excellent physical and mechanical properties over a wide temperature range and excellent electrical insulation. Even at high temperatures and high frequencies, its electrical properties remain good. It also exhibits good creep resistance, fatigue resistance, friction resistance, dimensional stability, resistance to organic solvents, and weather resistance. Its processability and physical properties can be improved through reinforcement, filling, and blending. Glass fiber reinforcement is particularly effective, increasing the rigidity, heat resistance, chemical resistance, electrical properties, and weather resistance of PET. The addition of flame retardants and anti-drip agents can improve its flame retardancy and self-extinguishing properties.

[0092] Photosensitive adhesive, also known as UV adhesive, ultraviolet adhesive, or shadowless adhesive, is an adhesive material that must be cured by ultraviolet radiation. The curing principle of photosensitive adhesive is that the photoinitiator in the UV-curing material absorbs ultraviolet light and produces active free radicals or cations, which trigger monomer polymerization and cross-linking chemical reactions, transforming the adhesive from a liquid to a solid state within seconds. Photosensitive adhesive is highly environmentally friendly, pollution-free, and has low flammability. It cures very quickly, taking from a few seconds to tens of seconds using UV curing equipment of varying power levels. It is well-suited for automated production lines and improves production efficiency. Photosensitive adhesive also has high bonding strength and is suitable for materials sensitive to temperature, solvents, and moisture.

[0093] In the embodiment of the present application, due to the high bonding strength of the photosensitive adhesive, the bonding between the protective layer of the photosensitive adhesive material and the adhesive layer is stronger, thereby making the bonding between the protective layer of the photosensitive adhesive material and the light-receiving surface of the battery cell stronger, and the protective layer of the photosensitive adhesive material is less likely to fall off from the light-receiving surface of the battery cell.

[0094] Under the irradiation of ultraviolet rays (for example, the irradiation time is 2 seconds), the photosensitive adhesive is cured into a solid state, and the cured photosensitive adhesive forms a protective layer of the photosensitive adhesive material.

[0095] In actual production, the adhesive of the EVA material is sprayed on a film (protective layer 11) of polyethylene terephthalate material or photosensitive adhesive material under high temperature and high pressure conditions, and is heated at a preset temperature (the preset temperature range is 90°C to 120°C) based on the heating time (the heating time range is 1 second to 3 seconds) to form an adhesive layer 12. Then, the protective layer 11 with the adhesive layer 12 is placed on the light-receiving surface 13 of the back-contact solar cell and pressed based on a pressing pressure (the pressing pressure range is 30 Newtons to 50 Newtons) so that the protective layer 11 with the adhesive layer 12 is adhered to the light-receiving surface 13 of the back-contact solar cell through the adhesive layer 12 to obtain the cell 10 provided in the embodiment of the present application.

[0096] Preferably, in some embodiments, the heat resistance temperature threshold is 200°C.

[0097] It should be noted that, when the heat resistance temperature threshold is 200°C, the material of the protective layer 11 can be polyethylene terephthalate material, and the heat resistance temperature of the polyethylene terephthalate material is in the range of 250°C to 255°C (for example, 255°C). The heat resistance temperature of the polyethylene terephthalate material is greater than or equal to the heat resistance temperature threshold (200°C), which can avoid the protective layer from melting easily during the production process of the photovoltaic module, causing the battery cells to stick to the production equipment and affecting the normal production of the photovoltaic module; in addition, the protective layer 11 can also be other materials with a heat resistance temperature greater than or equal to the heat resistance temperature threshold (200°C).

[0098] Optionally, referring to FIG3 , in some embodiments, the light-receiving surface 13 of the cell 10 is provided with a protective layer 11 formed of a polymer material; the light transmittance of the protective layer 11 is greater than a light transmittance threshold. Furthermore, the backlight surface 14 of the cell 10 provided in the embodiments of the present application is provided with an electrode 15 , which includes a positive electrode and a negative electrode.

[0099] The hardness of the protective layer 11 is within the hardness range, and the thickness of the protective layer 11 is within the thickness range; wherein, the hardness range is Shore hardness D55 to Shore hardness D85; the thickness range is 30 microns to 60 microns; the surface roughness of the protective layer 11 is within the roughness range, and the roughness range is 0.4 mm to 1 mm; the heat resistance temperature of the protective layer 11 is greater than or equal to the heat resistance temperature threshold, and the heat resistance temperature threshold is 160°C; preferably, in some embodiments, the heat resistance temperature threshold is 200°C; the transmittance threshold is 95%; the polymer material is one of polyethylene terephthalate and photosensitive adhesive.

[0100] The following three experiments were conducted using the cell provided in the embodiments of the present application. The thickness of the protective layer of the cell used in the experiment was 30 microns. The material of the protective layer was a photosensitive adhesive material, and the light transmittance of the photosensitive adhesive material was 98%.

[0101] (1) The adhesive layer of the EVA material used in the lamination process of the photovoltaic module production process is set on the protective layer of the battery cell, and a tensile test is performed. The tensile test result of the battery cell with the adhesive layer of the EVA material is 110 Newtons, and the tensile standard required by production is not less than 70 Newtons. Compared with the tensile test results (80 Newtons to 120 Newtons) of the battery cell without a protective layer in the prior art, the battery cell provided by the embodiment of the present application meets the tensile standard required by production and is within the test result range of the tensile test of the battery cell without a protective layer in the prior art.

[0102] (2) The protective layer of the embodiment of the present application is set on half of the light-receiving surface of the back-contact solar cell, and the protective layer of the embodiment of the present application is not set on the other half, and an experiment on the influence of light transmittance is carried out. After the back-contact solar cell has undergone the lamination process in the photovoltaic module production process, it is observed by naked eye and observed by a CCD (charge coupled device) camera with a magnification of 30 times. No boundary is found on the light-receiving surface of the back-contact solar cell where the protective layer of the embodiment of the present application is set and the other half where the protective layer of the embodiment of the present application is not set. Therefore, the protective layer of the embodiment of the present application has no obvious effect on the light transmittance of the photovoltaic module generated by the cell of the embodiment of the present application.

[0103] It should be noted that the lamination process in photovoltaic module production involves placing the laid glass layer, first adhesive layer, battery cell array, second adhesive layer, and backsheet into a laminator. The air inside the module is removed by vacuuming. Heat is then applied to melt the first and second adhesive layers, bonding the glass layer, battery cell array, and backsheet together to form the photovoltaic module. Both the first and second adhesive layers are made of EVA adhesive.

[0104] (3) Power experiments were conducted on the battery cells provided in the embodiments of the present application and the battery cells in the prior art, that is, power tests were conducted on the battery cells provided in the embodiments of the present application and the battery cells in the prior art respectively. The power test result of the battery cells provided in the embodiments of the present application was 433 watts, and the power test result of the battery cells in the prior art was 435 watts. Therefore, there is no significant difference in the power performance of the battery cells provided in the embodiments of the present application and the power performance of the battery cells in the prior art.

[0105] From the perspective of the type of cell material, the cell provided in the embodiments of the present application is generally a monocrystalline silicon solar cell, and the photoelectric conversion efficiency of a monocrystalline silicon solar cell can reach 28.7%. In addition, the cell provided in the embodiments of the present application can also be a heterojunction solar cell, and the photoelectric conversion efficiency of a heterojunction solar cell can reach 29.4%.

[0106] 4 , a photovoltaic module provided in an embodiment of the present application includes the aforementioned cell 10 .

[0107] In the embodiment of the present application, the photovoltaic module includes a glass layer 21, a first adhesive layer 22, a series group of battery cells 10, a second adhesive layer 23, a backplane 24, and an outer frame 25 in order from the front to the back. Since the battery cells form a complete interface with the first adhesive layer and the glass layer, the transmittance requirements are met, there is no need to remove the protective layer, and production efficiency is improved. The cell 10 provided in the present application is a back-contact solar cell; the light-receiving surface 13 of the cell 10 is sequentially provided with an adhesive layer 12 and a protective layer 11; the transmittance of the protective layer 11 is greater than the transmittance threshold; the first surface 111 of the protective layer 11 is bonded to the first surface 121 of the adhesive layer 12, and the second surface 122 of the adhesive layer 12 is bonded to the light-receiving surface 13 of the cell 10. Since the light-receiving surface 13 of the cell 10 is covered with the protective layer 11, it is possible to prevent the light-receiving surface 13 of the cell 10 from being scratched due to the stacking and transportation of the cell 10, and there is no need to place isolation paper between two adjacent cell cells 10, thereby reducing the failure rate of the production line and solving the problem in the prior art that, in order to prevent the light-receiving surface 13 of the cell 10 from being scratched due to the stacking and transportation of the cell 10, isolation paper is placed between two adjacent cell cells 10 during the production process of the photovoltaic module, resulting in the isolation paper being brought into the production line and causing failures.

[0108] The following describes in detail the battery cell packaging method provided in the embodiment of the present application through specific embodiments and application scenarios in conjunction with the accompanying drawings.

[0109] FIG5 is a flowchart of a method for packaging a battery cell according to an embodiment of the present application. As shown in FIG5 , the method may include:

[0110] Step 101: forming a polymer material covering layer on the light-receiving surface of the cell.

[0111] The light transmittance of the polymer material is greater than a light transmittance threshold, and the heat-resistant temperature of the polymer material is greater than or equal to a heat-resistant temperature threshold.

[0112] In the embodiment of the present application, a polymer material covering layer is formed on the light-receiving surface of the cell, and the covering layer is then cured to form a protective layer on the light-receiving surface of the cell.

[0113] It should be noted that the cell is a back-contact solar cell, which has a light-receiving surface and a backlight surface. The light-receiving surface is the side of the back-contact solar cell that absorbs sunlight, that is, the front of the back-contact solar cell; the backlight surface is the back of the back-contact solar cell, and the electrodes of the back-contact solar cell are all arranged on the backlight surface.

[0114] Polymer materials can include polyethylene glycol terephthalate (PET) and photosensitive adhesives (UV adhesives, UV stands for ultraviolet). PET is a milky white or light yellow, highly crystalline polymer with a smooth, glossy surface. It exhibits excellent physical and mechanical properties over a wide temperature range and excellent electrical insulation. Even at high temperatures and high frequencies, its electrical properties remain good. It also exhibits good creep resistance, fatigue resistance, friction resistance, dimensional stability, resistance to organic solvents, and weather resistance. Its processability and physical properties can be improved through reinforcement, filling, and blending. Glass fiber reinforcement is particularly effective, increasing the rigidity, heat resistance, chemical resistance, electrical properties, and weather resistance of PET. The addition of flame retardants and anti-drip agents can improve the flame retardancy and self-extinguishing properties of PET.

[0115] Photosensitive adhesive, also known as UV adhesive, ultraviolet adhesive, or shadowless adhesive, is an adhesive material that must be cured by ultraviolet radiation. The curing principle of photosensitive adhesive is that the photoinitiator in the UV-curing material absorbs ultraviolet light and produces active free radicals or cations, which trigger monomer polymerization and cross-linking chemical reactions, transforming the adhesive from a liquid to a solid state within seconds. Photosensitive adhesive is highly environmentally friendly, pollution-free, and has low flammability. It cures very quickly, taking from a few seconds to tens of seconds using UV curing equipment of varying power levels. It is well-suited for automated production lines and improves production efficiency. Photosensitive adhesive also has high bonding strength and is suitable for materials sensitive to temperature, solvents, and moisture.

[0116] The heat-resistant temperature of the polymer material is the melting point of the polymer material. When the temperature of the polymer material is higher than the heat-resistant temperature of the polymer material, the polymer material melts into a liquid state.

[0117] Step 102: solidify the cover layer to form a protective layer for the light-receiving surface of the cell.

[0118] In the embodiment of the present application, the cover layer is cured to form a protective layer on the light-receiving surface of the cell, thereby effectively protecting the light-receiving surface of the cell.

[0119] It should be noted that the covering layer is in liquid state before solidification and becomes solid state after solidification.

[0120] To sum up, in the embodiment of the present application, the battery cell is a back-contact solar cell, and a polymer material covering layer is formed on the light-receiving surface of the battery cell, the transmittance of the polymer material is greater than the transmittance threshold, and the heat resistance temperature of the polymer material is greater than or equal to the heat resistance temperature threshold; the covering layer is cured to form a protective layer for the light-receiving surface of the battery cell, so as to reduce the possibility of the light-receiving surface of the battery cell being scratched due to the stacking and transportation of the battery cell, and there is no need for staff to place isolation paper between two adjacent battery cells, thereby reducing the failure rate of the production line and solving the problem in the prior art that in order to reduce the possibility of the light-receiving surface of the battery cell being scratched due to the stacking and transportation of the battery cell, the staff placed isolation paper between two adjacent battery cells, resulting in the isolation paper being brought into the production line and causing failures.

[0121] FIG6 is a flowchart of specific steps of a battery cell packaging method provided in an embodiment of the present application. As shown in FIG6 , the method may include:

[0122] Step 201: Heat the polymer material to a first preset temperature to melt it into a liquid state, thereby forming a spray coating, wherein the first preset temperature is greater than the heat-resistant temperature.

[0123] In an embodiment of the present application, a polymer material is heated to a first preset temperature to melt into a liquid state to form a spray coating, and then the spray coating is sprayed onto the light-receiving surface according to a first preset pressure to form a covering layer.

[0124] Optionally, in some embodiments, the polymer material is polyethylene terephthalate.

[0125] In an embodiment of the present application, the polyethylene terephthalate material is heated to a first preset temperature to melt into a liquid state to form a spray coating, and then the spray coating is sprayed on the light-receiving surface according to a first preset pressure to form a covering layer.

[0126] Step 202: spray the spray coating onto the light-receiving surface according to a first preset pressure to form the covering layer.

[0127] In an embodiment of the present application, the spray coating is sprayed on the light-receiving surface according to a first preset pressure to form a covering layer.

[0128] It should be noted that the spray coating to be sprayed is in a sealed cavity and is sprayed through the nozzle in an atomized state so as to adhere to the light-receiving surface of the solar cell. The first preset pressure is the pressure at which the spray coating is sprayed at the nozzle. At the first preset pressure, the liquid spray coating is atomized.

[0129] Optionally, in some embodiments, the heat-resistant temperature is 255° C.; and the first preset pressure ranges from 0.4 kgf to 0.6 kgf.

[0130] In an embodiment of the present application, when the spray coating is heated to a first preset temperature, the first preset temperature is greater than the heat resistance temperature (255°C). At the first preset temperature, the spray coating of the polyethylene terephthalate material melts into a liquid state. Then, according to the first preset pressure, the spray coating can be atomized and sprayed on the light-receiving surface of the battery cell to form a covering layer of the polyethylene terephthalate material.

[0131] Specifically, in some embodiments, the first preset temperature may be 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, etc.; the first preset pressure may be 0.42 kgf, 0.44 kgf, 0.46 kgf, 0.48 kgf, 0.50 kgf, 0.52 kgf, 0.54 kgf, 0.56 kgf, 0.58 kgf, 0.60 kgf, etc.

[0132] It should be noted that kilogram-force (kgf) is a commonly used unit of force. The SI unit of force is the Newton. One kilogram-force refers to the weight exerted on a one-kilogram object and is approximately equal to 9.8 Newtons. The heat resistance temperature of polymer materials, such as polyethylene terephthalate, is 255°C.

[0133] Optionally, in some embodiments, step 202 includes the following sub-steps:

[0134] Sub-step 2021: spraying the spray coating material on the light-receiving surface according to a first preset pressure, and forming the spray coating material on the light-receiving surface into the covering layer when the thickness of the spray coating material on the light-receiving surface is within a thickness range;

[0135] Wherein, the thickness ranges from 30 microns to 60 microns.

[0136] In an embodiment of the present application, the spray coating is sprayed on the light receiving surface according to a first preset pressure, and when the thickness of the spray coating on the light receiving surface is within a thickness range (30 microns to 60 microns), the spray coating on the light receiving surface is formed into a covering layer.

[0137] Specifically, in some embodiments, the thickness of the spray coating on the light-receiving surface may be 30 microns, 35 microns, 40 microns, 45 microns, 50 microns, 55 microns, 60 microns, etc.

[0138] Step 203 : Based on the first curing time, the covering layer is cured at a second preset temperature to form the protective layer.

[0139] Wherein, the first curing time ranges from 10 seconds to 15 seconds, and the second preset temperature ranges from 5°C to 15°C.

[0140] In an embodiment of the present application, the covering layer is solidified, that is, the covering layer of liquid polyethylene terephthalate material is cooled so that the liquid covering layer becomes solid. Specifically, the liquid covering layer is cooled at a second preset temperature for a cooling time equal to the first solidification time to form a solid protective layer.

[0141] It should be noted that, air cooling is usually used to cool the covering layer to achieve solidification; the first solidification time can be 10 seconds, 11 seconds, 12 seconds, 13 seconds, 14 seconds, 15 seconds, etc.; the second preset temperature can be 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, etc.

[0142] By executing steps 201 to 203, the possibility of the light-receiving surface of the battery cells being scratched due to the stacking and transportation of the battery cells can be reduced, and there is no need for workers to place isolation paper between two adjacent battery cells, thereby reducing the failure rate of the production line. This solves the problem in the prior art that in order to reduce the possibility of the light-receiving surface of the battery cells being scratched due to the stacking and transportation of the battery cells, workers place isolation paper between two adjacent battery cells, resulting in the isolation paper being brought into the production line and causing failures.

[0143] Optionally, in some embodiments, step 203 may be replaced by the following step (step 204):

[0144] Step 204: Curing the covering layer. If the surface hardness of the solidified covering layer is within a hardness range and the thickness of the solidified covering layer is within a thickness range, the covering layer is determined to be the protective layer. The hardness range is Shore D55 to Shore D85, and the thickness range is 30 microns to 60 microns.

[0145] In the embodiment of the present application, after curing the covering layer, since the hardness of the surface of the solid covering layer is within the hardness range (Shore hardness D55 to Shore hardness D85), the effectiveness of the protective layer in protecting the light-exposed surface of the battery cell can be guaranteed; since the thickness of the solid covering layer is within the thickness range (30 microns to 60 microns), the protective layer is thinned, thereby meeting the demand for thinning of the battery cell.

[0146] It should be noted that Shore hardness refers to the reading of the value measured by a Shore hardness tester. Its unit is "degree". There are many types of Shore hardness testers, such as the Shore A hardness tester, whose range is 0-100HA; the Shore D hardness tester, whose range is 0-100HD.

[0147] Specifically, in some embodiments, the hardness of the surface of the solid covering layer is measured using a Shore D hardness tester. The hardness of the surface of the solid covering layer may be Shore D55, Shore D60, Shore D65, Shore D70, Shore D75, Shore D80, Shore D85, etc.; the thickness of the covering layer may be 30 microns, 35 microns, 40 microns, 45 microns, 50 microns, 55 microns, 60 microns, etc.

[0148] Optionally, in some embodiments, step 203 may be replaced by the following steps (step 205, step 206):

[0149] Step 205: Curing the covering layer. When the surface hardness of the solidified covering layer is determined to be within a hardness range and the thickness of the solidified covering layer is determined to be within a thickness range, the surface roughness of the solidified covering layer is determined. The hardness range is Shore D55 to Shore D85, and the thickness range is 30 microns to 60 microns.

[0150] In the embodiments of the present application, after curing the cover layer, since the surface hardness of the solidified cover layer is within the hardness range (Shore D55 to Shore D85), the effectiveness of the protective layer formed by the cover layer in protecting the light-exposed surface of the cell can be ensured; since the thickness of the solidified cover layer is within the thickness range (30 microns to 60 microns), the protective layer formed by the cover layer is thinned, thereby meeting the demand for thinning the cell. When it is determined that the surface hardness of the solidified cover layer is within the hardness range and the thickness of the solidified cover layer is within the thickness range, it is necessary to determine the surface roughness of the solidified cover layer to determine whether the surface roughness of the solidified cover layer is within the roughness range.

[0151] Step 206 : When the roughness of the surface of the solid-state covering layer is within a roughness range, determine that the covering layer is formed as the protective layer.

[0152] Wherein, the roughness range is 0.4 mm to 1 mm.

[0153] In an embodiment of the present application, after determining that the hardness of the surface of the solid-state covering layer is within the hardness range and the thickness of the solid-state covering layer is within the thickness range, the roughness of the surface of the solid-state covering layer is determined, and the roughness of the surface of the solid-state covering layer is judged. When the roughness of the surface of the solid-state covering layer is within the roughness range (0.4 mm to 1 mm), it is determined that the covering layer is formed as a protective layer. In the lamination process of the photovoltaic module production process, a glue layer of an adhesive of an EVA material is provided on the protective layer of the battery cell to bond the battery cell to the glass plate. Since the roughness of the surface of the solid-state covering layer is within the roughness range (0.4 mm to 1 mm), the roughness of the surface of the protective layer formed by the covering layer is within the roughness range (0.4 mm to 1 mm), which ensures that the interface formed by the contact between the surface of the protective layer formed by the covering layer and the glue layer of the adhesive can reduce the degree of specular reflection of the light, thereby improving the light transmittance.

[0154] It should be noted that the adhesive used for EVA material is EVA composite glue, a type of glue whose main ingredients are thermoplastic styrene-butadiene rubber, rosin-modified resin, petroleum resin, and solvent. EVA composite glue offers excellent bonding properties, a long aging time, and requires no water treatment. It can be applied in a single application, making it more convenient and more efficient. The cured product bonded with EVA composite glue is extremely flexible, can withstand severe drops and falls, and is not easily peeled, giving it excellent cushioning properties. EVA composite glue also has a low odor, meeting environmental and health standards. Furthermore, EVA composite glue exhibits high strength, transparency, and initial adhesion.

[0155] Specifically, in some embodiments, the roughness may be 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, etc.

[0156] By executing steps 205 to 206, the covering layer can be solidified to form the covering layer into a protective layer. Since the hardness of the surface of the solid covering layer is within the hardness range (Shore hardness D55 to Shore hardness D85), the effectiveness of the protective layer formed by the covering layer in protecting the light-receiving surface of the battery cell can be guaranteed; since the thickness of the solid covering layer is within the thickness range (30 microns to 60 microns), the protective layer formed by the covering layer is thinned, thereby meeting the demand for thinning of the battery cell; since the roughness of the surface of the solid covering layer is within the roughness range (0.4 mm to 1 mm), it is guaranteed that the interface formed by the surface of the protective layer formed by the covering layer and the adhesive layer can reduce the degree of specular reflection of light, thereby improving the light transmittance.

[0157] Optionally, in some embodiments, the transmittance threshold is 95%.

[0158] In the embodiment of the present application, since the transmittance of the protective layer of the cell is greater than the transmittance threshold (95%), it can be ensured that the cell can normally receive solar energy and operate normally.

[0159] Optionally, in some embodiments, the heat resistance temperature threshold is 160°C.

[0160] In the embodiment of the present application, the heat resistance temperature is greater than or equal to the heat resistance temperature threshold (160°C), which can prevent the protective layer from melting easily during the production process of the photovoltaic module, causing the battery cells to stick to the production equipment and affecting the normal production of the photovoltaic module.

[0161] It should be noted that the material of the protective layer can be polyethylene terephthalate material or photosensitive adhesive material. The transmittance of polyethylene terephthalate material and photosensitive adhesive material are both greater than 95%, and the reliability of polyethylene terephthalate material and photosensitive adhesive material are both greater than 25 years, which can meet the performance requirements of transmittance and reliability of the battery cell; the heat resistance temperature of polyethylene terephthalate material is in the range of 250°C to 255°C (for example, 255°C), and the heat resistance temperature of photosensitive adhesive material is 160°C. The heat resistance temperature of polyethylene terephthalate material and the heat resistance temperature of photosensitive adhesive material are both greater than or equal to the heat resistance temperature threshold (160°C), which can avoid the problem that the protective layer is easily melted during the production process of photovoltaic modules, causing the battery cells to stick to the production equipment and affecting the normal production of photovoltaic modules; in addition, the protective layer can also be other materials with a transmittance greater than 95%, a reliability greater than 25 years, and a heat resistance temperature greater than or equal to the heat resistance temperature threshold (160°C).

[0162] Preferably, in some embodiments, the heat resistance temperature threshold is 200°C.

[0163] It should be noted that when the heat resistance temperature threshold is 200°C, the material of the protective layer can be polyethylene terephthalate material. The heat resistance temperature of polyethylene terephthalate material is in the range of 250°C to 255°C (for example, 255°C). The heat resistance temperature of polyethylene terephthalate material is greater than or equal to the heat resistance temperature threshold (200°C), which can avoid the protective layer from melting easily during the production process of photovoltaic modules, causing the battery cells to stick to the production equipment and affecting the normal production of photovoltaic modules; in addition, the protective layer can also be other materials with a heat resistance temperature greater than or equal to the heat resistance temperature threshold (200°C).

[0164] The protective layer of the battery cell in the embodiment of the present application is a transparent protective layer; there are no bubbles inside the protective layer of the battery cell in the embodiment of the present application.

[0165] FIG7 is a flowchart of specific steps of another battery cell packaging method provided in an embodiment of the present application. As shown in FIG7 , the method may include:

[0166] Step 301: Spray the photosensitive adhesive material onto the light-receiving surface to form the covering layer according to a second preset pressure, wherein the second preset pressure ranges from 0.4 kgf to 0.6 kgf.

[0167] In an embodiment of the present application, the polymer material is a photosensitive adhesive material. Since the photosensitive adhesive is liquid at room temperature (the normal temperature range is 20°C to 30°C), the liquid photosensitive adhesive material is sprayed on the light-receiving surface according to the second preset pressure to form a covering layer.

[0168] It should be noted that the photosensitive adhesive material to be sprayed is in a sealed cavity and is sprayed through the nozzle in an atomized state so as to adhere to the light-receiving surface of the solar cell. The second preset pressure is the pressure at which the spray layer is sprayed at the nozzle. At the second preset pressure, the liquid photosensitive adhesive material is atomized.

[0169] Specifically, in some embodiments, the second preset pressure may be 0.42 kgf, 0.44 kgf, 0.46 kgf, 0.48 kgf, 0.50 kgf, 0.52 kgf, 0.54 kgf, 0.56 kgf, 0.58 kgf, 0.60 kgf, etc.

[0170] Step 302: Curing the cover layer under ultraviolet irradiation based on a second curing time period to form the protective layer, wherein the second curing time period ranges from 2 seconds to 3 seconds.

[0171] In an embodiment of the present application, the covering layer of the photosensitive adhesive material is cured, that is, the covering layer of the photosensitive adhesive material is irradiated with ultraviolet rays. Since the photosensitive adhesive material is cured under the irradiation of ultraviolet rays, the covering layer of the liquid photosensitive adhesive material is solid under the irradiation of ultraviolet rays. Specifically, the covering layer of the photosensitive adhesive material is irradiated with ultraviolet rays for a second curing time to form a solid protective layer.

[0172] It should be noted that a lamp emitting ultraviolet rays is usually used to irradiate the cover layer of the photosensitive adhesive material.

[0173] Specifically, in some embodiments, the second curing time may be 2 seconds, 2.5 seconds, 3 seconds, etc.

[0174] By executing steps 301 to 302, the possibility of the light-receiving surface of the battery cells being scratched due to the stacking and transportation of the battery cells can be reduced, and there is no need for workers to place isolation paper between two adjacent battery cells, thereby reducing the failure rate of the production line. This solves the problem in the prior art that in order to reduce the possibility of the light-receiving surface of the battery cells being scratched due to the stacking and transportation of the battery cells, workers place isolation paper between two adjacent battery cells, resulting in the isolation paper being brought into the production line and causing failures.

[0175] Optionally, in some embodiments, step 301 may be replaced by the following steps (sub-step 303):

[0176] Step 303: Print the photosensitive adhesive material on the light-receiving surface by screen printing according to a third preset pressure to form the covering layer.

[0177] Wherein, the third preset pressure ranges from 50 Newtons to 60 Newtons.

[0178] In an embodiment of the present application, the polymer material is a photosensitive adhesive material. Since the photosensitive adhesive is liquid at room temperature (the normal temperature range is 20°C to 30°C), according to the third preset pressure, the photosensitive adhesive material is printed on the light-receiving surface of the battery cell by screen printing to form a covering layer, and then the covering layer is cured to form a protective layer.

[0179] It should be noted that the process of setting a covering layer of photosensitive adhesive material on the light-receiving surface of the battery cell by screen printing is as follows: placing the screen printing plate on the light-receiving surface of the battery cell so that the bottom surface of the screen printing plate contacts the light-receiving surface of the battery cell, and then placing the photosensitive adhesive material at one end of the top surface of the screen printing plate, using a scraper to apply a third preset pressure to the photosensitive adhesive material at one end of the top surface of the screen printing plate, and at the same time moving at a uniform speed toward the other end of the top surface of the screen printing plate. During the movement, the photosensitive adhesive material is squeezed from the mesh of the screen printing plate to the light-receiving surface of the battery cell by the scraper, thereby completing the setting of the covering layer of photosensitive adhesive material on the light-receiving surface of the battery cell.

[0180] Specifically, in some embodiments, the third preset pressure may be 50 Newtons, 52 Newtons, 54 Newtons, 56 Newtons, 58 Newtons, 60 Newtons, etc.

[0181] Optionally, in some embodiments, step 302 may be replaced by the following step (step 304):

[0182] Step 304 : solidifying the covering layer, and forming the covering layer into the protective layer when the hardness of the surface of the covering layer formed into a solid state is within a hardness range and the thickness of the covering layer formed into a solid state is within a thickness range.

[0183] The hardness range is from Shore D55 to Shore D85; and the thickness range is from 30 microns to 60 microns.

[0184] The implementation of this step is similar to the implementation process of the above step 204 and will not be repeated here.

[0185] Optionally, in some embodiments, step 302 may be replaced by the following steps (step 305, step 306):

[0186] Step 305 : solidify the covering layer, and when it is determined that the hardness of the surface of the solid covering layer is within a hardness range and the thickness of the solid covering layer is within a thickness range, determine the roughness of the surface of the solid covering layer.

[0187] The hardness range is from Shore D55 to Shore D85; and the thickness range is from 30 microns to 60 microns.

[0188] The implementation of this step is similar to the implementation process of the above step 205 and will not be repeated here.

[0189] Step 306 : When the surface roughness of the solid-state covering layer is within a roughness range, forming the covering layer into the protective layer.

[0190] Wherein, the roughness range is 0.4 mm to 1 mm.

[0191] The implementation of this step is similar to the implementation process of the above step 206 and will not be repeated here.

[0192] Optionally, in some embodiments, the transmittance threshold is 95%.

[0193] In the embodiment of the present application, since the transmittance of the protective layer of the cell is greater than the transmittance threshold (95%), it can be ensured that the cell can normally receive solar energy and operate normally.

[0194] Optionally, in some embodiments, the heat resistance temperature threshold is 160°C.

[0195] In the embodiment of the present application, the heat resistance temperature is greater than or equal to the heat resistance temperature threshold (160°C), which can prevent the protective layer from melting easily during the production process of the photovoltaic module, causing the battery cells to stick to the production equipment and affecting the normal production of the photovoltaic module.

[0196] It should be noted that the material of the protective layer can be polyethylene terephthalate material or photosensitive adhesive material. The transmittance of polyethylene terephthalate material and photosensitive adhesive material is greater than 95%, and the reliability of polyethylene terephthalate material and photosensitive adhesive material is greater than 25 years, which can meet the performance requirements of transmittance and reliability of the battery cell; the heat resistance temperature of polyethylene terephthalate material is in the range of 250°C to 255°C (for example, 255°C), and the heat resistance temperature of photosensitive adhesive material is 160°C. The heat resistance temperature of polyethylene terephthalate material and the heat resistance temperature of photosensitive adhesive material are both greater than or equal to the heat resistance temperature threshold (160°C), which can avoid the problem that the protective layer is easily melted during the production process of photovoltaic modules, causing the battery cells to stick to the production equipment and affecting the normal production of photovoltaic modules; in addition, the protective layer can also be other materials with a transmittance greater than 95%, a reliability greater than 25 years, and a heat resistance temperature greater than or equal to the heat resistance temperature threshold (160°C).

[0197] Preferably, in some embodiments, the heat resistance temperature threshold is 200°C.

[0198] It should be noted that when the heat resistance temperature threshold is 200°C, the material of the protective layer can be polyethylene terephthalate material. The heat resistance temperature of polyethylene terephthalate material is in the range of 250°C to 255°C (for example, 255°C). The heat resistance temperature of polyethylene terephthalate material is greater than or equal to the heat resistance temperature threshold (200°C), which can avoid the protective layer from melting easily during the production process of photovoltaic modules, causing the battery cells to stick to the production equipment and affecting the normal production of photovoltaic modules; in addition, the protective layer can also be other materials with a heat resistance temperature greater than or equal to the heat resistance temperature threshold (200°C).

[0199] The protective layer of the battery cell in the embodiment of the present application is a transparent protective layer; there are no bubbles inside the protective layer of the battery cell in the embodiment of the present application.

[0200] Optionally, in some embodiments, the cell packaging method provided in the embodiments of the present application includes providing a protective layer on the light-receiving surface of the cell, wherein the light transmittance of the protective layer is greater than a light transmittance threshold; and the heat resistance temperature of the protective layer is greater than or equal to the heat resistance temperature threshold. The protective layer is a film, and the protective layer is made of polyethylene terephthalate or a photosensitive adhesive. Providing the protective layer on the light-receiving surface of the cell includes: obtaining the protective layer, forming an adhesive layer on the protective layer, and providing the protective layer on the light-receiving surface of the cell through the adhesive layer.

[0201] It should be noted that, the forming of the adhesive layer on the protective layer includes: spraying the adhesive on the protective layer to form an adhesive covering layer; based on a preset time, the adhesive covering layer is heated at a third preset temperature to form the adhesive layer; the setting of the protective layer on the light-receiving surface of the battery cell through the adhesive layer includes: placing the protective layer on the light-receiving surface of the battery cell through the adhesive layer, so that the adhesive layer is arranged between the protective layer and the light-receiving surface of the battery cell; based on the pressing pressure, the protective layer is pressed so that the protective layer is adhered to the light-receiving surface of the battery cell through the adhesive layer; wherein, the preset time range is 1 second to 3 seconds, the third preset temperature range is 90°C to 120°C, and the pressing pressure range is 30 Newtons to 50 Newtons.

[0202] In summary, since the light-receiving surface of the battery cell is covered with a protective layer, it can prevent the light-receiving surface of the battery cell from being scratched due to the stacking and transportation of the battery cell, and there is no need to place isolation paper between two adjacent battery cells, thereby reducing the failure rate of the production line.

[0203] Although the embodiments of the present application are described above, the present application is not limited to the above-mentioned specific embodiments and application fields. The above-mentioned specific embodiments are merely illustrative and instructive, and not restrictive. A person of ordinary skill in the art, under the guidance of this specification and without departing from the scope of protection of the claims of this application, can also make many forms, all of which fall within the scope of protection of this application.

Claims

1. A cell, the cell being a back contact solar cell, wherein: The light-receiving surface of the cell is provided with a protective layer, the light transmittance of the protective layer is greater than a light transmittance threshold, and the heat-resistant temperature of the protective layer is greater than or equal to the heat-resistant temperature threshold.

2. The battery cell according to claim 1, wherein: An adhesive layer is provided between the protective layer and the light-receiving surface of the cell; The first surface of the protective layer is bonded to the first surface of the adhesive layer, and the second surface of the adhesive layer is bonded to the light-receiving surface of the battery cell.

3. The battery cell according to claim 2, wherein: The adhesive layer includes a plurality of adhesive portions, and the adhesive portions are evenly or unevenly distributed on the entire or partial area of ​​the light receiving surface.

4. The battery cell according to claim 2, wherein: The thickness of the adhesive layer ranges from 5 microns to 10 microns.

5. The battery cell according to claim 1, wherein: The material of the protective layer is one of polyethylene terephthalate material and photosensitive adhesive material.

6. The battery cell according to claim 2, wherein: When the material of the protective layer is a photosensitive adhesive material, the protective layer is a protective layer formed by the cured photosensitive adhesive material; and / or The adhesive layer is made of ethylene vinyl acetate copolymer material.

7. The battery cell according to claim 1, wherein: At least one side of the protective layer is a frosted surface; The thickness of the protective layer is within a thickness range, and the thickness range is 30 microns to 60 microns; The roughness of the first surface of the protective layer is in the range of 0.4 mm to 1.0 mm; and / or: the roughness of the second surface of the protective layer is in the range of 0.4 mm to 1.0 mm.

8. The battery cell according to claim 1, wherein: The hardness of the protective layer is within a hardness range, and the hardness range is from Shore hardness D55 to Shore hardness D85; The light transmittance threshold is 95%; and / or the heat resistance temperature threshold is 160°C or 200°C.

9. A photovoltaic module, wherein: A battery cell comprising any one of claims 1 to 8.

10. A method for packaging a battery cell, wherein the battery cell is a back contact solar cell, wherein: The method comprises: A protective layer is arranged on the light-receiving surface of the battery cell, wherein the light transmittance of the protective layer is greater than a light transmittance threshold value; and the heat-resistant temperature of the protective layer is greater than or equal to the heat-resistant temperature threshold value.

11. The method according to claim 10, wherein: The step of providing a protective layer on the light-receiving surface of the cell comprises: A polymer material covering layer is formed on the light-receiving surface of the cell, and the light transmittance of the polymer material is greater than the light transmittance Threshold value, the heat-resistant temperature of the polymer material is greater than or equal to the heat-resistant temperature threshold value; The cover layer is cured to form a protective layer for the light-receiving surface of the cell.

12. The method according to claim 11, wherein: The step of forming a polymer material covering layer on the light-receiving surface of the cell comprises: Heating the polymer material to a first preset temperature to melt it into a liquid state to form a spray coating, wherein the first preset temperature is greater than the heat-resistant temperature; According to a first preset pressure, the spray coating material is sprayed on the light receiving surface to form the covering layer; Among them, the heat resistance temperature is 255°C; and the first preset pressure ranges from 0.4 kgf to 0.6 kgf.

13. The method according to claim 12, wherein: The step of curing the cover layer to form a protective layer on the light-receiving surface of the cell comprises: Based on the first curing time, at a second preset temperature, curing the covering layer to form the protective layer; Wherein, the first curing time ranges from 10 seconds to 15 seconds, and the second preset temperature ranges from 5 degrees to 15 degrees.

14. The method according to claim 12, wherein: The step of spraying the spray coating material on the light receiving surface according to the first preset pressure to form the covering layer comprises: According to a first preset pressure, the spray coating material is sprayed on the light-receiving surface, and when the thickness of the spray coating material on the light-receiving surface is within a thickness range, the spray coating material on the light-receiving surface is formed into the covering layer; Wherein, the thickness ranges from 30 microns to 60 microns.

15. The method according to claim 11, wherein: The polymer material is a photosensitive adhesive material; The step of forming a polymer material covering layer on the light-receiving surface of the cell comprises: According to a second preset pressure, the photosensitive adhesive material is sprayed on the light receiving surface to form the covering layer; the second preset pressure ranges from 0.4 kgf to 0.6 kgf; or: According to a third preset pressure, the photosensitive adhesive material is printed on the light receiving surface by screen printing to form the covering layer; the third preset pressure ranges from 50 Newtons to 60 Newtons.

16. The method according to claim 15, wherein: The step of curing the cover layer to form a protective layer on the light-receiving surface of the cell comprises: Based on a second curing time, the covering layer is cured under the irradiation of ultraviolet rays to form the protective layer; the second curing time ranges from 2 seconds to 3 seconds.

17. The method according to claim 11, wherein: The step of curing the cover layer to form a protective layer on the light-receiving surface of the cell comprises: Curing the covering layer, and forming the covering layer into the protective layer when the hardness of the surface of the covering layer formed into a solid state is within a hardness range and the thickness of the covering layer formed into a solid state is within a thickness range; or: The covering layer is solidified, and when it is determined that the hardness of the surface of the covering layer formed into a solid state is within a hardness range and the thickness of the covering layer formed into a solid state is within a thickness range, the roughness of the surface of the covering layer formed into a solid state is determined; when the roughness of the surface of the covering layer formed into a solid state is within a roughness range, the covering layer is formed into the protective layer; The hardness range is from Shore hardness D55 to Shore hardness D85; the thickness range is from 30 micrometers to 60 micrometers; and the roughness range is from 0.4 millimeters to 1 millimeter.

18. The method according to claim 10, wherein: The protective layer is a film, and the protective layer is a polyethylene terephthalate material or a photosensitive adhesive material; the protective layer is provided on the light-receiving surface of the battery cell, including: Obtaining the protective layer, and forming an adhesive layer on the protective layer; The protective layer is disposed on the light-receiving surface of the cell through the adhesive layer.

19. The method according to claim 18, wherein: The step of forming an adhesive layer on the protective layer comprises: spraying an adhesive on the protective layer to form an adhesive covering layer; Based on a preset time, the adhesive covering layer is heated at a third preset temperature to form the bonding layer; The preset time period ranges from 1 second to 3 seconds, and the third preset temperature ranges from 90° C. to 120° C.

20. The method according to claim 18, wherein: The step of disposing the protective layer on the light-receiving surface of the cell through the adhesive layer comprises: Placing the protective layer on the light-receiving surface of the cell through the adhesive layer, so that the adhesive layer is disposed between the protective layer and the light-receiving surface of the cell; Based on the pressing pressure, the protective layer is pressed so that the protective layer is adhered to the light-receiving surface of the battery cell through the adhesive layer; Wherein, the pressing pressure ranges from 30 Newtons to 50 Newtons.

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