Battery piece, preparation method of battery piece, battery string and photovoltaic module

Abstract

The invention discloses a battery piece, a preparation method of the battery piece, a battery string and a photovoltaic module, and belongs to the technical field of photovoltaics. The cutting surface comprises two end parts and a middle part positioned between the two end parts; the surface roughness of the end part is greater than that of the middle part; the end part comprises a first surface and a second surface; the first surface and the second surface are arranged in a step shape; in the thickness direction of the battery piece, the first surface is close to one side of the backlight surface, and the second surface is close to one side of the illuminated surface; the roughness of the first surface is larger than that of the second surface. According to the invention, the two rough surfaces with the height difference are formed at the two end parts of the cutting surface corresponding to the chamfering position, so that more light can be absorbed.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a solar cell, a method for preparing the solar cell, a solar cell string, and a photovoltaic module. Background Technology

[0002] In the field of solar cell manufacturing, lasers are commonly used to cut solar cells into multi-segment forms such as two-segments and four-segments. These segments are then wired together in a specific arrangement to form solar cell strings, which are finally encapsulated into photovoltaic modules. In actual cell string arrangements, the cut surfaces of the solar cells are often adjacent to the uncut surfaces of adjacent cells, and the two ends of the uncut surfaces usually have chamfered structures. More light enters at the chamfered locations, but due to the lack of specific design for the morphology of the cut surfaces in current technology, the light reflectivity at the chamfered locations is higher, and the light absorption is lower, thus affecting the module's power performance. Therefore, how to increase the light absorption of the chamfered cell sides is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0003] The purpose of this application is to provide a solar cell, a method for preparing the solar cell, a solar cell string, and a photovoltaic module, thereby increasing the light absorption rate of the solar cell side at the chamfered position.

[0004] To achieve the above objectives, this application provides a battery cell, comprising: at least one cut surface; the cut surface includes two ends and a middle portion located between the two ends; the surface roughness of the ends is greater than the surface roughness of the middle portion; the ends include a first surface and a second surface; the first surface and the second surface are arranged in a stepped manner; in the thickness direction of the battery cell, the first surface is closer to the backlight side, and the second surface is closer to the light-receiving side; the roughness of the first surface is greater than the roughness of the second surface.

[0005] Optionally, in a direction perpendicular to the cut surface, the first surface is lower than the second surface.

[0006] Optionally, the area of ​​the first surface accounts for less than or equal to 30% of the total area of ​​the first surface and the second surface;

[0007] And / or, in the first direction, the length of the first surface accounts for 0.1%-1.0% of the total length of the cut surface, including the values ​​at both ends;

[0008] And / or, in the second direction, the width of the first surface accounts for 10%-20% of the total width of the cut surface, including the values ​​at both ends.

[0009] Optionally, in the second direction, the width of the first surface is 20μm-80μm, including the values ​​at both ends.

[0010] Optionally, the first surface has a plurality of protrusions; the protrusions are unevenly distributed.

[0011] Optionally, the second surface has a plurality of first ribs; the first ribs are curved; the first ribs extend along a second direction and are arranged sequentially along a first direction.

[0012] Optionally, the spacing between adjacent first ribs gradually decreases along the direction away from the end.

[0013] Optionally, the second surface further has a plurality of second ribs; the second ribs are curved; the second ribs extend along the second direction and are arranged sequentially along the first direction;

[0014] The inclination direction of the second rib is opposite to that of the first rib; a portion of the first rib intersects with a portion of the second rib.

[0015] Optionally, the first rib is inclined in a direction away from the end; the average inclination angle of the first rib is 90°-180°, including the values ​​at both ends;

[0016] And / or, the average tilt angle of the second rib is 0-90°, including the value at the right end.

[0017] Optionally, the cut surface is provided with a passivation layer and / or an anti-reflection layer.

[0018] Optionally, the ratio of the surface roughness of the end portion to the surface roughness of the middle portion is 1.2-10, including the values ​​at both ends.

[0019] Optionally, the ratio of the surface roughness of the first surface to the surface roughness of the second surface is 1.1-4, including the values ​​at both ends.

[0020] To achieve the above objectives, this application also provides a method for preparing a solar cell, comprising:

[0021] Provide battery cells to be cut;

[0022] The back surface of the battery cell to be cut is grooved by the first laser treatment to form two grooves, exposing the first surface;

[0023] A second laser treatment is used to split the groove and the area between the two grooves to form a cutting surface.

[0024] Optionally, the step of grooving the back surface of the battery cell to be cut by a first laser treatment includes:

[0025] The back surface of the battery cell to be cut is irradiated with a first laser to create a groove; the first laser is a low-power pulsed infrared laser.

[0026] Optionally, the step of splitting the groove at its location and the location between the two grooves using a second laser process includes:

[0027] A second laser is used to irradiate the location of the groove and the location between the two grooves, and water mist is sprayed at the location between the two grooves to cleave the fragment using the thermal effect; the second laser is a high-power continuous infrared laser.

[0028] Optionally, a passivation layer and / or an antireflection layer may be prepared on the formed cut surface.

[0029] To achieve the above objectives, this application also provides a battery string, characterized in that it comprises: at least two battery cells connected in series; the battery cells include those described above.

[0030] The cut surface of the battery cell is placed opposite the uncut surface of the adjacent battery cell; both ends of the uncut surface have chamfers; and the two ends of the cut surface are respectively placed opposite the two chamfers.

[0031] To achieve the above objectives, this application also provides a photovoltaic module, comprising: a back cover plate, a back encapsulant film, a battery string layer, a front encapsulant film, and a front cover plate stacked together; the battery string layer comprises battery strings as described above.

[0032] Obviously, the solar cell provided in this application achieves regional control of the morphology of the cut surface along the thickness direction of the solar cell, so that both ends of the cut surface corresponding to the chamfer position form rough surfaces with two different roughnesses. The roughness of the rough surface near the backlight surface of the solar cell is greater than that near the light-receiving surface. Simultaneously, there is a height difference between the two rough surfaces. The rough cut surface can increase the amount of light absorbed, and the concavity of the rough cut surface into the solar cell can absorb even more light. This application also provides a method for preparing the solar cell, a solar cell string, and a photovoltaic module, which have the aforementioned beneficial effects. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0034] Figure 1This is a schematic diagram of the structure of a battery cell provided in an embodiment of this application;

[0035] Figure 2 A scanning electron microscope image of a cut surface at 120x magnification, provided as an embodiment of this application;

[0036] Figure 3 A partial scanning electron microscope image of a cut surface at 250x magnification is provided for an embodiment of this application;

[0037] Figure 4 A scanning electron microscope image of a first rib at 600x magnification, provided for an embodiment of this application;

[0038] Figure 5 A scanning electron microscope image of a second rib at 250x magnification, provided for an embodiment of this application;

[0039] Figure 6 A top view of a battery string provided in an embodiment of this application;

[0040] Figure 7 A side view of a battery string provided in an embodiment of this application;

[0041] Figure 8 This is a flowchart illustrating a method for preparing a battery cell according to an embodiment of this application.

[0042] The annotations in the attached figures are explained as follows:

[0043] 1-Battery cell; 11-Cut surface; 111-First surface; 112-Second surface; 12-Light-receiving surface; 13-Backlight surface; 14-Uncut surface; 1121-First rib; 1122-Second rib; 2-Chamfer. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0045] Please refer to Figures 1 to 3 , Figure 1 This is a schematic diagram of the structure of a battery cell provided in an embodiment of this application; Figure 2 A scanning electron microscope image of a cut surface 11 provided for an embodiment of this application; Figure 3A partial scanning electron microscope image of a cut surface provided in an embodiment of this application, wherein the battery cell 1 may include:

[0046] At least one cut surface 11; the cut surface 11 includes two ends and a middle portion located between the two ends; the surface roughness of the ends is greater than the surface roughness of the middle portion; the ends include a first surface 111 and a second surface 112; the first surface 111 and the second surface 112 are arranged in a stepped manner; in the thickness direction of the battery cell 1, the first surface 111 is closer to the backlight surface 13, and the second surface 112 is closer to the light-receiving surface 12; the roughness of the first surface 111 is greater than the roughness of the second surface 112.

[0047] In this embodiment, the battery cell 1 can be prepared by cutting the solar cell 1 with a laser to obtain a two-piece or four-piece battery cell 1. At least one side of the cut semi-finished battery cell 1 is a cut surface 11 (the cut surface 11 is not covered by other film layers at this time).

[0048] In this embodiment, the roughness of the first surface 111 can be greater than the roughness of the second surface 112, and the roughness of the second surface 112 can be greater than the surface roughness of the middle part. Accordingly, the surface roughness of the end formed by the first surface 111 and the second surface 112 is greater than the surface roughness of the middle part.

[0049] This embodiment does not limit the specific manner of the stepped arrangement. For example, in the direction perpendicular to the cut surface 11, the first surface 111 may be lower than the second surface 112. It should be noted that the roughness of the first surface 111 is greater than that of the second surface 112, and the first surface 111 is recessed into the battery cell 1 compared to the second surface 112, which can absorb more light.

[0050] This embodiment does not limit the specific structure of the first surface 111 and the second surface 112. The roughness of the first surface 111 and the second surface 112 are different, and different microstructures can be used to achieve them, for example:

[0051] The first surface 111 may have a number of protrusions; the protrusions may be unevenly distributed; thus, the first surface 111 may have an uneven structure.

[0052] The second surface 112 may have a plurality of first ribs 1121; the first ribs 1121 may be curved; the first ribs 1121 may extend along a second direction and be arranged sequentially along a first direction, such as... Figure 4 As shown. It should be noted that in this embodiment, the first direction is perpendicular to the second direction; the second direction is parallel to the thickness direction of the battery cell 1.

[0053] Furthermore, in this embodiment, the spacing between adjacent first ribs 1121 can gradually decrease along the direction away from the end. It should be noted that in this embodiment, the spacing between adjacent first ribs 1121 gradually decreases along this direction, which makes the roughness greater closer to the end, thereby increasing the diffuse reflection of light at the chamfer position and thus increasing the light absorption rate.

[0054] Furthermore, such as Figure 5 As shown, in this embodiment, the second surface 112 may also have a plurality of second ribs 1122; the second ribs 1122 may be curved; the second ribs 1122 may extend along a second direction and be arranged sequentially along a first direction; the inclination direction of the second ribs 1122 may be opposite to the inclination direction of the first ribs 1121; some of the first ribs 1121 may intersect with some of the second ribs 1122. It should be noted that the second surface 112 in this embodiment has two types of ribs, which can increase the roughness of the second surface 112 to increase the diffuse reflection of light at the chamfer position, thereby increasing the light absorption rate; at the same time, it can reduce specular reflection.

[0055] This embodiment does not limit the specific tilt angle of the first rib 1121. For example, the first rib 1121 may tilt away from the end. The average tilt angle of the first rib 1121 may be 90°-180°, including the values ​​at both ends. This embodiment does not limit the specific tilt angle of the second rib 1122. For example, the average tilt angle of the second rib 1122 may be 0-90°, including the value at the right end.

[0056] This embodiment does not limit the specific shape of the second surface 112, for example, it can adopt the following shape:

[0057] The second surface 112 may extend along a first direction from the side of one end away from the other end, and the length of the second surface 112 in the first direction may be equal to the length of the first surface 111 in the first direction.

[0058] Alternatively, the second surface 112 may include a first region and a second region; the first region is near the side of the light-receiving surface 12 and extends along a first direction from the side of one end away from the other end; the second region is near the side of the backlight surface 13 and extends along the first direction from the side of the first surface 111 near the other end; the total length of the first surface 111 and the second region in the first direction is equal to the length of the first region in the first direction.

[0059] This embodiment does not limit the specific area of ​​the first surface 111. For example, the area of ​​the first surface 111 may account for less than or equal to 30% of the total area of ​​the first surface 111 and the second surface 112.

[0060] This embodiment does not limit the specific ratio of the length of the first surface 111 and the second surface 112 to the total length of the cutting surface 11. For example, in the first direction, the length of the whole formed by the first surface 111 and the second surface 112 can account for 0.1% to 2.0% of the total length of the cutting surface 11, including the values ​​at both ends. Preferably, in the first direction, the length of the whole formed by the first surface 111 and the second surface 112 can be 0.1mm to 3.0mm, including the values ​​at both ends.

[0061] It should be noted that in this embodiment, the first surface 111 is roughly rectangular. This embodiment does not limit the specific length of the first surface 111. For example, in the first direction, the length of the first surface 111 as a percentage of the total length of the cut surface 11 can be 0.1%-1.0%, including the values ​​at both ends. It should also be noted that the first surface 111 is lower than the second surface 112. The longer the first surface 111, the more light is absorbed. However, because the battery cell 1 forms a depression on the first surface 111, it can damage the battery cell 1, so the surface cannot be too long. Therefore, the length of the first surface 111 can be determined by balancing these two effects.

[0062] This embodiment does not limit the specific width of the first surface 111. For example, in the second direction, the width of the first surface 111 can account for 10%-20% of the total width of the cut surface 11, including the values ​​at both ends. It should be noted that by adopting an appropriate width ratio for the first surface 111 in this embodiment, it is possible to effectively avoid the first surface 111 being too wide, which would increase the diffuse reflection range and intensity of light, causing the light to be refracted through the chamfered position and reducing the light absorption rate; conversely, it is possible to avoid the first surface 111 being too narrow, which would reduce the diffuse reflection range and intensity of light, causing the light to directly penetrate the back of the battery through the chamfered position and reduce the light absorption rate. Preferably, in the second direction, the width of the first surface 111 is 20μm-80μm, including the values ​​at both ends.

[0063] It should be noted that in this embodiment, the first surface 111 has several protrusions, and the second surface 112 has several ribs. The first surface 111 and the second surface 112 together form an uneven structure. The surface roughness of the middle part is less than that of the end face formed by the first surface 111 and the second surface 112, and is smoother than that end face. This embodiment does not limit the specific structure of the middle part; for example, the middle part can have a fine corrugated structure.

[0064] It should be noted that, in this embodiment, the length of the middle portion in the first direction is the difference between the total length of the cutting surface 11 in the first direction and the length of the end portion formed by the first surface 111 and the second surface 112 in the first direction. This embodiment does not limit the specific length of the middle portion; for example, in the first direction, the length of the middle portion can be 150mm-250mm, including the values ​​at both ends.

[0065] Furthermore, in this embodiment, a passivation layer and / or an anti-reflection layer may be provided on the cut surface 11 with the above-described structure. It should be noted that the cut surface 11 in this embodiment is formed through a cutting process, which may result in surface defects. By providing a passivation layer, the impact of surface defects on battery performance can be reduced; by providing an anti-reflection layer, the reflectivity of light on the cut surface 11 can be reduced. This embodiment does not limit the specific type of passivation layer, as long as it can repair the defects. This embodiment does not limit the specific number of passivation layers, which can be determined according to actual conditions. This embodiment does not limit the specific type of anti-reflection layer, as long as it can reduce light reflection. This embodiment does not limit the specific number of anti-reflection layers, which can be determined according to actual conditions.

[0066] This embodiment features a cut surface with a passivation layer and / or an antireflection layer. The specific roughness of the ends and the middle portion is not limited. For example, the ratio of the surface roughness of the ends to that of the middle portion can be 1.2-10, including the values ​​at both ends. It should be noted that a greater surface roughness at the ends than in the middle portion allows for the absorption of more light.

[0067] In this embodiment, the cut surfaces with passivation and / or antireflection layers are not limited in terms of the specific roughness of the first surface 111 and the second surface 112. For example, the ratio of the roughness of the first surface 111 to the roughness of the second surface 112 can be 1.1-4, including the right-hand side. It should be noted that the roughness of the first surface 111 is greater than that of the second surface 112, which allows it to absorb more light.

[0068] Based on the above embodiments, this application performs regional control of the morphology of the cut surface along the thickness direction of the battery cell, so that both ends of the cut surface corresponding to the chamfer position form rough surfaces with two different roughnesses, wherein the roughness of the rough surface near the backlight surface of the battery cell is greater than the roughness of the rough surface near the light-receiving surface of the battery cell; at the same time, there is a height difference between the two rough surfaces, the rough cut surface can increase the amount of light absorbed, and the rough cut surface is concave in the battery cell, which can absorb more light.

[0069] Please refer to Figure 6 , Figure 6 This is a top view of a battery string provided in an embodiment of this application. The battery string may include at least two battery cells 1 connected in series; the battery cells 1 include the battery cells 1 described above.

[0070] The cut surface 11 of the battery cell 1 is placed opposite to the uncut surface 14 of the adjacent battery cell 1; both ends of the uncut surface 14 have chamfers; the two ends of the cut surface 11 are respectively placed opposite to the two chamfers.

[0071] like Figure 7 As shown, the uncut surface 14 of adjacent battery cells 1 has a chamfer. Light enters from the front through the chamfer and after multiple reflections and refractions by the adhesive film in the gap between battery cells 1, it is reflected to the cut surface 11 of battery cell 1. The end of the cut surface 11 corresponds to the chamfer, so more light will reach the end of the cut surface 11. The second surface 112 at the end is rough, which can increase the amount of light absorbed. The first surface 111 is concave and rougher, which can absorb more light.

[0072] Based on the above embodiments, this application uses the above-described battery cell, and therefore also has the above-described beneficial effects.

[0073] The photovoltaic module provided in this application embodiment may include: a back cover plate, a back encapsulating film, a battery string layer, a front encapsulating film, and a front cover plate stacked together; the battery string layer includes battery strings as described above.

[0074] Based on the above embodiments, this application uses the above-described battery cell, and therefore also has the above-described beneficial effects.

[0075] Please refer to Figure 8 , Figure 8 A flowchart illustrating a method for preparing a battery cell according to an embodiment of this application is provided. This method may include:

[0076] S101: Provides battery cells to be cut.

[0077] This embodiment does not limit the specific type of battery cell to be cut.

[0078] S102: The back surface of the cell to be cut is grooved by the first laser treatment to form two grooves and expose the first surface.

[0079] This embodiment does not limit the specific method of the first laser treatment, as long as it ensures that a groove can be formed and the first surface exposed. For example, a first laser can be used to irradiate the back surface of the battery cell to be cut to create a groove. The first laser can be a low-power pulsed infrared laser. The process parameters of the first laser can include: power of 5W-70W, including both values; frequency of 10Hz-200Hz, including both values; and wavelength of 1000nm-1200nm, including both values. In addition, the process parameters of the first laser can also include: irradiation width and irradiation time, etc.

[0080] It should be noted that in this embodiment, after slotting the back of the battery cell, the sidewall of the resulting groove is the first surface. The first laser treatment not only forms a groove on the back surface but also affects the area surrounding the groove (including the area corresponding to the second surface). In this embodiment, the parameters of the first and second surfaces (including size, shape, and roughness) can be controlled by adjusting the process parameters of the first laser.

[0081] S103: The groove and the area between the two grooves are split by a second laser process to form a cutting surface.

[0082] This embodiment does not limit the specific method of the second laser treatment, as long as it ensures that the battery cell to be cut can be cracked, exposing the second surface and the middle part. For example, a second laser can be used to irradiate the groove and the area between the two grooves, and water mist can be sprayed at the area between the two grooves to utilize the thermal effect to crack the cell. The second laser can be a high-power continuous infrared laser. The process parameters of the second laser can include: power of 100W-500W, including the values ​​at both ends; wavelength of 1000nm-1200nm, including the values ​​at both ends. In addition, the process parameters of the second laser can also include: frequency, irradiation width, and irradiation time, etc.

[0083] It should be noted that, because this embodiment uses thermal stress cutting to form the cutting surface, the resulting second surface may have an inclination angle in the thickness direction of the battery cell.

[0084] It should be noted that after the dicing is completed in this embodiment, a second surface (the end of the cutting surface formed by the first surface and the corresponding second surface) and the remaining cutting surface (i.e., the middle part of the cutting surface) are exposed. The middle part of the cutting surface is formed only under the second laser treatment, while the second surface is formed under the combined action of the first and second laser treatments. Therefore, the roughness of the second surface and the middle part are different; the roughness of the second surface is greater than that of the middle part. In this embodiment, the parameters of the second surface and the middle part (including size, shape, and roughness) can be controlled by adjusting the process parameters of the second laser.

[0085] Based on the above embodiments, the above-mentioned battery cell can be prepared by the preparation method of this application, and therefore has the same beneficial effects as described above.

[0086] In one possible embodiment, this embodiment may further include, after step S103: depositing a passivation layer on the cut surface using ALD (Atomic Layer Deposition) or PECVD (Plasma-Enhanced Chemical Vapor Deposition); the reaction gas source used in the deposition process includes silane, ammonia, trimethylaluminum and nitrous oxide.

[0087] It should be noted that the cut surface in this embodiment is formed by a cutting process, which will result in surface defects. By setting a passivation layer, the impact of surface defects on battery performance can be reduced. The passivation layer in this embodiment can be one or more of silicon nitride, silicon oxide, silicon oxynitride, and aluminum oxide.

[0088] In one possible embodiment, this embodiment may further include, after step S103, depositing an antireflection layer on the cut surface. The antireflection layer in this embodiment may be one or more of silicon nitride, silicon oxide, silicon oxynitride, and aluminum oxide.

[0089] It should be noted that, in this embodiment, by setting an anti-reflection layer, the reflectivity of light on the cut surface can be reduced.

[0090] In one possible embodiment, this embodiment includes:

[0091] In step S102: a first laser can be used to irradiate the back surface of the battery cell to be cut to make a groove, and a number of first ribs are formed in the battery cell at the bottom of the groove; the first ribs are curved; the first ribs extend along the second direction and are arranged sequentially along the first direction;

[0092] In step S103: a second laser can be used to irradiate the location of the groove, exposing the second surface at the bottom of the groove, and forming a plurality of second ribs on the second surface; the second ribs are curved; the second ribs extend along the second direction and are arranged sequentially along the first direction; the inclination direction of the second ribs is opposite to the inclination direction of the first ribs; some of the first ribs may intersect with some of the second ribs.

[0093] It should be noted that the second surface in this embodiment has two types of ribs, which can increase the roughness of the second surface to increase the diffuse reflection of light at the chamfer position, thereby increasing the light absorption rate; at the same time, it can reduce specular reflection.

[0094] In one possible implementation, based on the above embodiments, this embodiment can further reduce the spacing between adjacent first ribs along the direction away from the end by controlling the power of the first laser.

[0095] It should be noted that in this embodiment, the spacing between adjacent first ribs gradually decreases along this direction, which makes the roughness greater closer to the end, thereby increasing the diffuse reflection of light at the chamfer position and thus increasing the light absorption rate.

[0096] The cut surface of the battery cell obtained by the preparation method of this embodiment includes two ends and a middle part located between the two ends; the ends include a first surface and a second surface; the first surface and the second surface are arranged in a stepped shape.

[0097] Example 1:

[0098] The preparation process in this embodiment is as follows:

[0099] 1. Provide the battery cells to be cut;

[0100] 2. The back surface of the battery cell to be cut is irradiated with a first laser (a low-power pulsed infrared laser is used in this embodiment) to create two grooves, exposing the first surface;

[0101] The process parameters of the first laser include: power of 24W; frequency of 82Hz; wavelength of 1060nm;

[0102] 3. A second laser (a high-power continuous infrared laser in this embodiment) is used to irradiate the location of the groove and the area between the two grooves. Water mist is sprayed at the area between the two grooves to utilize the thermal effect to cleave the surface, thus preparing the desired product. Figure 1 The battery cell shown has a first surface and a second surface;

[0103] The process parameters of the second laser include: power of 250W and wavelength of 1050nm.

[0104] Example 2:

[0105] The preparation process in this embodiment is as follows:

[0106] 1. Provide the battery cells to be cut;

[0107] 2. The back surface of the battery cell to be cut is irradiated with a first laser (a low-power pulsed infrared laser is used in this embodiment) to create two grooves, exposing the first surface;

[0108] The process parameters of the first laser include: power of 99 W; frequency of 27 Hz; wavelength of 1000 nm;

[0109] 3. The second laser (a high-power continuous infrared laser is used in this embodiment) is used to irradiate the position of the groove and the position between the two grooves, and water mist is sprayed at the position between the two grooves. The thermal effect is used to split the cell and form a cutting surface, thus preparing a battery cell with a first surface and a second surface.

[0110] The process parameters of the second laser include: any value for power of 100W; wavelength of 1000nm.

[0111] Example 3:

[0112] The preparation process in this embodiment is as follows:

[0113] 1. Provide the battery cells to be cut;

[0114] 2. The back surface of the battery cell to be cut is irradiated with a first laser (a low-power pulsed infrared laser is used in this embodiment) to create two grooves, exposing the first surface;

[0115] The process parameters of the first laser include: power of 53W; frequency of 163Hz; and wavelength of 1190nm.

[0116] 3. The second laser (a high-power continuous infrared laser is used in this embodiment) is used to irradiate the position of the groove and the position between the two grooves, and water mist is sprayed at the position between the two grooves. The thermal effect is used to split the cell and form a cutting surface, thus preparing a battery cell with a first surface and a second surface.

[0117] The process parameters of the second laser include: power of 450W and wavelength of 1130nm.

[0118] Example 4:

[0119] The preparation process in this embodiment is as follows:

[0120] 1. Provide the battery cells to be cut;

[0121] 2. The back surface of the battery cell to be cut is irradiated with a first laser (a low-power pulsed infrared laser is used in this embodiment) to create two grooves, exposing the first surface;

[0122] The process parameters of the first laser include: power of 65W; frequency of 184Hz; wavelength of 1200nm;

[0123] 3. The second laser (a high-power continuous infrared laser is used in this embodiment) is used to irradiate the position of the groove and the position between the two grooves, and water mist is sprayed at the position between the two grooves. The thermal effect is used to split the cell and form a cutting surface, thus preparing a battery cell with a first surface and a second surface.

[0124] The process parameters of the second laser include: power of 500W and wavelength of 1180nm.

[0125] Example 5:

[0126] The preparation process in this embodiment is as follows:

[0127] 1. Provide the battery cells to be cut;

[0128] 2. The back surface of the battery cell to be cut is irradiated with a first laser (a low-power pulsed infrared laser is used in this embodiment) to create two grooves, exposing the first surface;

[0129] The process parameters of the first laser include: power of 16W; frequency of 58Hz; wavelength of 1020nm;

[0130] 3. The second laser (a high-power continuous infrared laser is used in this embodiment) is used to irradiate the position of the groove and the position between the two grooves, and water mist is sprayed at the position between the two grooves. The thermal effect is used to split the cell and form a cutting surface, thus preparing a battery cell with a first surface and a second surface.

[0131] The process parameters of the second laser include: power of 150W and wavelength of 1030nm.

[0132] Example 6:

[0133] The preparation process in this embodiment is as follows:

[0134] 1. Provide the battery cells to be cut;

[0135] 2. The back surface of the battery cell to be cut is irradiated with a first laser (a low-power pulsed infrared laser is used in this embodiment) to create two grooves, exposing the first surface;

[0136] The process parameters of the first laser include: power of 37W; frequency of 117Hz; wavelength of 1080nm;

[0137] 3. The second laser (a high-power continuous infrared laser is used in this embodiment) is used to irradiate the position of the groove and the position between the two grooves, and water mist is sprayed at the position between the two grooves. The thermal effect is used to split the cell and form a cutting surface, thus preparing a battery cell with a first surface and a second surface.

[0138] The process parameters of the second laser include: power of 350W and wavelength of 1070nm.

[0139] Comparative Example 1:

[0140] 1. Provide the battery cells to be cut;

[0141] 2. The back surface of the battery cell to be cut is irradiated with a first laser (a low-power pulsed infrared laser is used in this embodiment) to create two grooves, exposing the first surface;

[0142] The process parameters of the first laser include: power of 3W; frequency of 5Hz; wavelength of 1060nm;

[0143] 3. The second laser (a high-power continuous infrared laser is used in this embodiment) is used to irradiate the position of the groove and the position between the two grooves, and water mist is sprayed at the position between the two grooves. The thermal effect is used to split the cell and form a cutting surface, thus preparing a battery cell with a first surface and a second surface.

[0144] The process parameters of the second laser include: power of 50W and wavelength of 1050nm.

[0145] Comparative Example 2:

[0146] The preparation process in this embodiment is as follows:

[0147] 1. Provide the battery cells to be cut;

[0148] 2. The back surface of the battery cell to be cut is irradiated with a first laser (a low-power pulsed infrared laser is used in this embodiment) to create two grooves, exposing the first surface;

[0149] The process parameters of the first laser include: any value of power up to 90W; any value of frequency up to 300Hz; and a wavelength of 1060nm.

[0150] 3. The second laser (a high-power continuous infrared laser is used in this embodiment) is used to irradiate the position of the groove and the position between the two grooves, and water mist is sprayed at the position between the two grooves. The thermal effect is used to split the cell and form a cutting surface, thus preparing a battery cell with a first surface and a second surface.

[0151] The process parameters of the second laser include: any value for power of 600W; wavelength of 1050nm.

[0152] The structural parameters of the solar cells in each component obtained by the different preparation methods described above are shown in Table 1. Table 1: Structural parameters of solar cells in each component.

[0153]

[0154] The control and experimental components described above were subjected to I (current)-V (voltage) tests, and the electrical performance parameters of each component are shown in Table 2. The specific testing methods for the electrical performance parameters are as follows:

[0155] I. Preparatory work before testing

[0156] 1. Cleaning the battery cells

[0157] Wipe the surface with ultrapure water, ethanol or isopropanol to remove fingerprints, dust and organic residue;

[0158] After drying with nitrogen, let it stand for 10 minutes to avoid surface contamination affecting optical properties.

[0159] 2. Electrode contact inspection

[0160] Use a four-wire probe (such as the Keithley 2400 series) to ensure that the contact resistance between the metal electrode and the probe is <0.1Ω.

[0161] Use silver paste or spring probes to secure the battery and avoid pressure damage.

[0162] 3. Stabilization treatment

[0163] Ageing for 1 hour under standard illumination (1000W / m²) to eliminate light-induced degradation (LID).

[0164] The temperature control stage is maintained at 25℃±0.5℃ to avoid the influence of thermal effects on carrier mobility.

[0165] 4. Equipment calibration

[0166] Use a standard reference cell (such as an NREL calibration cell) to calibrate the light source spectrum to AM1.5G (wavelength range 300-1200nm).

[0167] Irradiance uniformity is controlled within ±2%, and temperature sensor error is < ±0.1℃.

[0168] II. Testing Equipment and Conditions

[0169] 1. Core equipment

[0170] IV tester: Keysight B2900A series, resolution voltage 0.1mV, current 0.1μA;

[0171] Solar simulator: Class AAA, pulsed or steady-state light source (e.g., Wacom WXS-200S-20);

[0172] Temperature control console: Thermoelectric cooling (TEC) module, accuracy ±0.2℃;

[0173] Spectral response instrument: Quantum efficiency (QE) testing system (such as Bentham PVE300).

[0174] 2. Standard Test Conditions (STC)

[0175] Irradiance: 1000 W / m² (AM1.5G spectrum);

[0176] Temperature: 25℃±1℃ (real-time monitoring via TEC);

[0177] Light spot uniformity: >95% coverage of the effective battery area.

[0178] III. Key Parameter Testing Procedures

[0179] 1. Conversion efficiency (Eta) and IV characteristics (Voc, Isc, FF)

[0180] Equipment: Solar simulator + IV tester + four-wire probe.

[0181] step:

[0182] a. Place the battery in the center of the simulator, covering the edges by 5mm to prevent light leakage from the edges;

[0183] b. Apply a scan voltage from -0.5V to Voc+0.5V in 10mV steps and record the IV curve;

[0184] c. Extract Voc (voltage when current = 0) and Isc (current when voltage = 0) from the curve;

[0185] d. Calculate the maximum power point (Pmax = Vmpp × Impp), and the fill factor FF = Pmax / (Voc × Isc);

[0186] e. Efficiency Eta = (Pmax / incident light power) × 100% (incident light power is calibrated using a standard cell).

[0187] Table 2 Electrical performance parameters of each component

[0188]

[0189] According to Tables 1 and 2, compared with Example 1, Comparative Example 1 reduces the power of the first laser and the power of the second laser, thereby reducing the electrical performance of the battery module; compared with Example 1, Comparative Example 2 increases the power of the first laser and the power of the second laser, thereby reducing the electrical performance of the battery module.

[0190] This document uses specific examples to illustrate the principles and implementation methods of this application, and the various embodiments are progressively related. Each embodiment focuses on the differences from other embodiments, and similar or identical parts between embodiments can be referred to interchangeably. For those skilled in the art, various improvements and modifications can be made to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

[0191] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

Claims

1. A type of battery cell, characterized in that, include: At least one cut surface; the cut surface includes two ends and a middle portion located between the two ends; the surface roughness of the ends is greater than the surface roughness of the middle portion; the ends include a first surface and a second surface; the first surface and the second surface are arranged in a stepped manner; in the thickness direction of the battery cell, the first surface is closer to the backlight side and the second surface is closer to the light-receiving side; the roughness of the first surface is greater than the roughness of the second surface.

2. The battery cell according to claim 1, characterized in that, In a direction perpendicular to the cut surface, the first surface is lower than the second surface.

3. The battery cell according to claim 1, characterized in that, The area of ​​the first surface accounts for less than or equal to 30% of the total area of ​​the first surface and the second surface; And / or, in the first direction, the length of the first surface accounts for 0.1%-1.0% of the total length of the cut surface, including the values ​​at both ends; And / or, in the second direction, the width of the first surface accounts for 10%-20% of the total width of the cut surface, including the values ​​at both ends.

4. The battery cell according to claim 3, characterized in that, In the second direction, the width of the first surface is 20μm-80μm, including the values ​​at both ends.

5. The battery cell according to claim 1, characterized in that, The first surface has a plurality of protrusions; the protrusions are unevenly distributed.

6. The battery cell according to claim 1, characterized in that, The second surface has a plurality of first ribs; the first ribs are curved; the first ribs extend along a second direction and are arranged sequentially along a first direction.

7. The battery cell according to claim 6, characterized in that, Along the direction away from the end, the spacing between adjacent first ribs gradually decreases.

8. The battery cell according to claim 6, characterized in that, The second surface also has a plurality of second ribs; the second ribs are curved; the second ribs extend along the second direction and are arranged sequentially along the first direction; The inclination direction of the second rib is opposite to that of the first rib; a portion of the first rib intersects with a portion of the second rib.

9. The battery cell according to claim 8, characterized in that, The first rib is inclined away from the end; the average inclination angle of the first rib is 90°-180°, including the values ​​at both ends; And / or, the average tilt angle of the second rib is 0-90°, including the value at the right end.

10. The battery cell according to claim 1, characterized in that, The cut surface is provided with a passivation layer and / or an anti-reflection layer.

11. The battery cell according to claim 10, characterized in that, The ratio of the surface roughness of the end portion to the surface roughness of the middle portion is 1.2-10, including the values ​​at both ends.

12. The battery cell according to claim 10, characterized in that, The ratio of the surface roughness of the first surface to the surface roughness of the second surface is 1.1-4, including the values ​​at both ends.

13. A method for preparing a battery cell, characterized in that, include: Provide battery cells to be cut; The back surface of the battery cell to be cut is grooved by the first laser treatment to form two grooves, exposing the first surface; A second laser treatment is used to split the groove and the area between the two grooves to form a cutting surface.

14. The battery cell according to claim 13, characterized in that, The process of creating grooves on the back surface of the battery cell to be cut using a first laser treatment includes: The back surface of the battery cell to be cut is irradiated with a first laser to create a groove; the first laser is a low-power pulsed infrared laser.

15. The battery cell according to claim 13, characterized in that, The step of splitting the groove at its position and the position between the two grooves by a second laser processing includes: A second laser is used to irradiate the location of the groove and the location between the two grooves, and water mist is sprayed at the location between the two grooves to cleave the fragment using the thermal effect; the second laser is a high-power continuous infrared laser.

16. The battery cell according to claim 13, characterized in that, A passivation layer and / or an antireflection layer are prepared on the formed cut surface.

17. A battery string, characterized in that, include: At least two solar cells connected in series; the solar cells include those as described in any one of claims 1 to 12; The cut surface of the battery cell is placed opposite the uncut surface of the adjacent battery cell; both ends of the uncut surface have chamfers; and the two ends of the cut surface are respectively placed opposite the two chamfers.

18. A photovoltaic module, characterized in that, include: A back cover, a back adhesive film, a battery string layer, a front adhesive film, and a front cover are stacked together; the battery string layer includes the battery string as described in claim 16.

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