Laser Grooving Method and Its Application in the Preparation of TOPCon Cells

Abstract

The present invention provides a laser grooving method and its application in the preparation of TOPCon cells, relating to the technical field of solar cells. The laser grooving method includes the following steps: using a laser to groove the front surface of the cell to form a dot matrix light spot; wherein, the repetition frequency of the laser is 1500 - 2500KHZ, the single pulse energy of the laser is 0.3 - 0.8μj, and the diameter of the light spot is 30 - 70μm. The laser grooving method provided by the present invention uses high-frequency low-pulse laser to groove the front surface of the cell to form a dot matrix small light spot, which can avoid the damage to the alumina passivation layer and the problem of uneven depth in the grooving area caused by local repeated grooving by large light spot laser.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a laser grooving method and its application in the preparation of TOPCon cells. Background Art

[0002] Electroplating is one of the most feasible ways for the metallization of TOPCon solar cells. Before electroplating, the cell wafers need to be laser grooved to break the insulating silicon nitride layer, so that metal ions can undergo a reduction reaction in the damaged area during subsequent electroplating to form metal. When laser grooving the front side of TOPCon cells, while damaging the surface silicon nitride layer, it is inevitable to damage the aluminum oxide passivation layer under the silicon nitride layer, affecting the open voltage and efficiency of the cells.

[0003] In the prior art, when laser grooving the front side of TOPCon cells, laser grooving is carried out in a full-coverage manner in the grid line area of the cells. Due to the lack of a Poly layer buffer on the front side of TOPCon cells, while laser destroying the surface thin silicon nitride layer, it will also damage the aluminum oxide passivation layer under the silicon nitride layer in a large area. At the same time, the local repeated grooving caused by large-spot lasers results in uneven depths in the grooved area, seriously affecting the electroplating effect, increasing the series resistance, and affecting current transmission; the higher pulse energy will also damage the aluminum oxide passivation layer and affect the passivation effect, and even damage the deep PN junction, affecting the open voltage and efficiency of the cells.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] One of the purposes of the present invention is to provide a laser grooving method, which includes the following steps: using a laser to groove the front side of a cell wafer to form a dot matrix light spot; wherein, the repetition frequency of the laser is 1500 - 2500KHZ, the single pulse energy of the laser is 0.3 - 0.8μj, and the diameter of the light spot is 30 - 70μm. The laser grooving method provided by the present invention uses high-frequency low-pulse lasers to groove the front side of the cell wafer to form a dot matrix small light spot, which can avoid damaging the aluminum oxide passivation layer and the problem of uneven depths in the grooved area caused by local repeated grooving of large-spot lasers.

[0006] Another purpose of the present invention is to provide an application of the above laser grooving method in the preparation of TOPCon cells. The TOPCon cells prepared by using the laser grooving method provided by the present invention have strong welding tensile force between the solder tape and the Pad point and high cell efficiency.

[0007] In order to achieve the above purposes of the present invention, the following technical solutions are specifically adopted:

[0008] In a first aspect, the present invention provides a laser grooving method, the laser grooving method comprising the following steps: using a laser to groove the front side of a cell to form a dot matrix spot; wherein the repetition frequency of the laser is 1500-2500 KHZ, for example, 1500 KHZ, 1600 KHZ, 1700 KHZ, 1800 KHZ, 1900 KHZ, 2000 KHZ, 2100 KHZ, 2200 KHZ, 2 300KHZ, 2400KHZ, 2500KHZ, etc., the single pulse energy of the laser is 0.3-0.8μj, for example, it can be 0.3μj, 0.4μj, 0.5μj, 0.6μj, 0.7μj, 0.8μj, etc., the diameter of the light spot is 30-70μm, for example, it can be 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, etc.

[0009] In the present invention, a high-frequency low-pulse laser with a frequency of 1500KHZ to 2500KHZ and a pulse frequency of 0.3 to 0.8μj is used, which can completely open the front silicon nitride layer while avoiding damage to the aluminum oxide passivation layer as much as possible, reducing the recombination of minority carriers inside the battery. At the same time, a small spot array laser with a diameter of 30-70μm can avoid the uneven depth of the grooved area caused by local repeated grooving caused by a large spot laser, and can also meet the requirements of the bonding force of the larger electroplated grid line and the smaller series resistance in the later stage, thereby improving the electroplating effect and the efficiency of the finished battery.

[0010] Preferably, the power percentage of the laser is 10-40%, for example, it may be 10%, 15%, 20%, 25%, 30%, 35%, 40% and the like.

[0011] Preferably, the beam type of the laser is a flat-top beam;

[0012] In the present invention, the type of laser beam used for grooving is a flat-top beam. The light spot energy emitted by the flat-top beam laser is uniform, which can evenly destroy the silicon nitride layer to ensure the bonding strength of the subsequent electroplated gate line without damaging the deeper P-type crystalline silicon layer and PN junction, thereby ensuring the opening voltage and efficiency of the battery.

[0013] Preferably, the laser comprises an ultraviolet picosecond laser or an ultraviolet nanosecond laser.

[0014] Preferably, the depth of the light spot is 90-110nm, for example, it can be 90nm, 91nm, 92nm, 93nm, 94nm, 95nm, 96nm, 97nm, 98nm, 99nm, 100nm, 101nm, 102nm, 103nm, 104nm, 105nm, 107nm, 108nm, 109nm, 110nm, etc.

[0015] Preferably, the light spot disposed in the grid line region is the first light spot, and a plurality of uniformly arranged first light spots are disposed in the grid line region;

[0016] Preferably, the center distance between adjacent first light spots is 30 - 140 um, for example, it can be 30 um, 35 um, 40 um, 45 um, 50 um, 55 um, 60 um, 65 um, 70 um, 75 um, 80 um, 85 um, 90 um, 95 um, 100 um, 105 um, 110 um, 115 um, 120 um, 125 um, 130 um, 135 um, 140 um, etc.;

[0017] Preferably, adjacent first light spots are tangent or have a spacing;

[0018] Preferably, the center distance between adjacent first light spots is less than or equal to the diameter of the first light spot;

[0019] Preferably, the arrangement form of the plurality of first light spots is an array arrangement or a plum blossom arrangement.

[0020] In the present invention, the dot matrix laser grooving method is used to groove the front side of the battery, avoiding full - coverage laser grooving in the grid line region of the battery, only damaging the silicon nitride insulating layer in the dot matrix region, reducing the damage to the aluminum oxide passivation layer, and still being able to achieve the passivation effect of the aluminum oxide layer outside the dot matrix region. Moreover, in the grid line region, the dot matrix laser light spots do not overlap, avoiding over - deep local grooving and damaging the PN junction, improving the open - circuit voltage and efficiency of the battery. At the same time, the closest distance between adjacent light spots does not exceed the diameter of the light spot, which can ensure the subsequent electroplating effect and the bonding force of the grid line.

[0021] Preferably, the light spot disposed in the Pad point region is the second light spot. Taking the second light spot as the central light spot, a plurality of second light spots are evenly distributed around the center of the central light spot. Taking the central light spot and its surrounding second light spots as a light spot unit, a plurality of uniformly arranged light spot units are disposed in the Pad point region;

[0022] Preferably, there are 6 second light spots evenly distributed around the center of the central light spot;

[0023] Preferably, the center distance between each adjacent second light spot is less than or equal to the diameter of the second light spot and greater than or equal to 0.875 times the diameter of the second light spot;

[0024] Preferably, each adjacent light spot unit is tangent or has a spacing;

[0025] Preferably, the spacing between adjacent light spot units is less than or equal to the diameter of the second light spot;

[0026] Preferably, the arrangement form of the plurality of light spot units is an array arrangement or a plum blossom arrangement.

[0027] In the present invention, within the Pad point area, a 7-point combined dot matrix pattern is used for grooving. The spot size does not need to be adjusted. After the 7 spots are connected as a whole, dot matrix arrangement is carried out, which can further improve the grid line bonding force and ensure the welding tensile force between the solder tape and the Pad point.

[0028] Preferably, before laser grooving, the solar cell is subjected to a first cleaning.

[0029] Preferably, the first cleaning includes: immersing and cleaning the solar cell in a first cleaning solution.

[0030] Preferably, the first cleaning solution includes at least one of toluene, methanol, acetone, and ethanol.

[0031] Preferably, the cleaning treatment time is 20 - 120 s, such as 20 s, 25 s, 30 s, 35 s, 40 s, 45 s, 50 s, 55 s, 60 s, 65 s, 70 s, 75 s, 80 s, 85 s, 90 s, 95 s, 100 s, 105 s, 110 s, 115 s, 120 s, etc., and the treatment temperature is 25 - 40 °C, such as 25 °C, 30 °C, 35 °C, 40 °C, etc.

[0032] In the present invention, before laser grooving, the surface of the solar cell is subjected to a first cleaning to ensure the uniformity of subsequent laser grooving on the front surface of the solar cell, and to ensure the bonding force of the electroplated grid line and the open voltage and efficiency of the solar cell. Among them, the concentration of the first cleaning solution is not limited as long as it can achieve the cleaning effect.

[0033] Preferably, after grooving, the solar cell is subjected to a second cleaning.

[0034] Preferably, the second cleaning includes: immersing and cleaning the grooved solar cell in a second cleaning solution.

[0035] Preferably, the second cleaning solution is an aqueous solution of hydrofluoric acid with a mass fraction of 0.5 - 5%, such as 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.

[0036] Preferably, during the second cleaning process, the solar cell is subjected to ultrasonic cleaning.

[0037] Preferably, the power of the ultrasonic wave is 30 - 90 W, such as 30 W, 35 W, 40 W, 45 W, 50 W, 55 W, 60 W, 65 W, 70 W, 75 W, 80 W, 85 W, 90 W, etc.

[0038] Preferably, the temperature of ultrasound is 25-40°C, for example, 25°C, 30°C, 35°C, 40°C, etc., and the time of ultrasound is 30-90s, for example, 30s, 35s, 40s, 45s, 50s, 55s, 60s, 65s, 70s, 75s, 80s, 85s, 90s, etc.

[0039] In the present invention, the slotted cell is ultrasonically cleaned in a second cleaning solution to remove oxide impurities and dust in the lattice grooves, thereby ensuring the bonding strength of the subsequent electroplated grid lines, reducing the contact resistance between the grid lines and the cell, and improving the cell efficiency.

[0040] Furthermore, the laser grooving method comprises the following steps:

[0041] a. Soak the battery cell in the first cleaning solution for cleaning;

[0042] b. Use laser to groove the front of the cell to form a dot matrix spot;

[0043] c. Perform low-power ultrasonic cleaning on the slotted battery cells in the second cleaning solution.

[0044] In a second aspect, the present invention provides an application of the laser grooving method in the preparation of TOPCon batteries.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The laser grooving method provided by the present invention adopts a high-frequency low-pulse laser with a frequency of 1500KHZ to 2500KHZ and a 0.3-0.8μj frequency, which can completely open the front silicon nitride layer while avoiding damage to the aluminum oxide passivation layer as much as possible, reducing the recombination of minority carriers inside the battery. At the same time, a small spot array laser with a diameter of 30-70μm can avoid the uneven depth of the grooving area caused by local repeated grooving caused by a large spot laser, and can also meet the requirements of the bonding force of a larger electroplated grid line and a smaller series resistance in the later stage, thereby improving the electroplating effect and the efficiency of the finished battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 A schematic structural diagram of a first light spot in a grid line region provided by an embodiment of the present invention;

[0049] Figure 2 Schematic diagram of the first light spots arranged in an array within the gate line region;

[0050] Figure 3 Schematic diagram of the first light spots arranged in a plum blossom pattern within the gate line region;

[0051] Figure 4 Schematic diagram of the structure of the light spot unit composed of the second light spots within the Pad point region;

[0052] Figure 5 Schematic diagram of the structure of the light spot unit within the Pad point region;

[0053] Figure 6 Schematic diagram of the light spot units arranged in an array within the Pad point region;

[0054] Figure 7 Schematic diagram of the light spot units arranged in a plum blossom pattern within the Pad point region. Detailed implementation manners

[0055] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meanings and scopes of the terms should be clear. However, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or extrinsic definition. In this application, unless otherwise specified, the use of "or" means "and / or". In addition, the use of the term "comprising" and other forms is non-restrictive.

[0056] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0057] The laser grooving pattern in the laser grooving method provided by the present invention is a uniform dot matrix pattern, and the pattern is divided into two parts: the light spots set in the gate line region are the first light spots, and there are several uniformly arranged first light spots in the gate line region; the light spots set in the Pad point region are the second light spots. The gate lines in the gate line region are used for conducting electricity, and the Pad points in the Pad point region are used for welding the solder tapes in the later stage. Since the gate lines and Pad points are all prior arts, they will not be elaborated herein.

[0058] Among them, several uniformly arranged first light spots are set in the gate line region, such as Figure 1As shown, the diameter of the first light spot is set to a, where a is 30 - 70 μm, the depth of the light spot is 90 - 110 nm, the distance between the centers of two adjacent first light spots is set to b, where b is 30 - 140 μm, and adjacent first light spots are tangent or have a spacing (i.e., no overlapping area), that is, b ≥ a. At the same time, the maximum distance between adjacent first light spots does not exceed the diameter of the light spot, that is, b - a ≤ a. An example of the arrangement of grid line light spots is as Figure 2 and Figure 3 shown Figure 2 In which, the arrangement form of the first light spots is an array arrangement Figure 3 In which, the arrangement form of the first light spots is a plum blossom arrangement

[0059] Taking the light spot set in the Pad point area as the second light spot, with the second light spot as the central light spot, several second light spots are evenly distributed around the center of the central light spot. Taking the central light spot and the second light spots around it as a light spot unit, several uniformly arranged light spot units are set in the Pad point area. Specifically, a 7 - point combined dot matrix pattern is used for grooving in the Pad point area, such as Figure 4 shown Figure 4 A light spot unit consists of 7 second light spots. One light spot and the 6 adjacent light spots form a light spot unit. The centers of the 6 adjacent light spots are located on the circumference of a circle with the center of the central light spot as the center and a radius of length b. That is, the distance between the centers of two adjacent second light spots is set to b. The diameter a of each second light spot is 30 - 70 μm, the depth of the second light spot is 90 - 110 nm, and adjacent light spots are connected, that is, b ≤ a. At the same time, to avoid damage to the alumina layer caused by complete overlap, it is necessary to satisfy b ≥ 0.875a; as Figure 5 shown, the distance between the centers of two light spot units is c, and adjacent light spot units are tangent or have a spacing (i.e., non - overlapping), that is, c ≥ 2b + a, and the maximum distance between each adjacent light spot unit does not exceed the diameter of the second light spot, that is, c - (2b + a) ≤ a. An example of the light spot arrangement in the Pad point area is as Figure 6 and Figure 7 shown Figure 6 In which, the arrangement form of the light plate units is an array arrangement Figure 7 In which, the arrangement form of the light plate units is a plum blossom arrangement

[0060] The present invention will be further described below through embodiments. Unless otherwise specified, the materials in the embodiments are prepared according to existing methods or directly purchased from the market

[0061] Embodiment 1

[0062] This embodiment provides a laser grooving method, including the following steps

[0063] a. Immerse the solar cell in the first cleaning solution for soaking and cleaning; wherein, the first cleaning solution is toluene, the cleaning treatment time is 20 s, and the treatment temperature is 40 °C;

[0064] b. Use a laser to groove the front side of the solar cell to form a dot matrix light spot;

[0065] Among them, the repetition frequency of the laser is 1500 KHZ, the single pulse energy of the laser is 0.8 μj, the power percentage of the laser is 10%, the beam type of the laser is a flat-top beam, and the laser used is an ultraviolet picosecond laser;

[0066] Among them, the depth of all the light spots is 110 nm;

[0067] Among them, the diameter a of the light spot in the grid line area is 30 μm, the distance b between the centers of two adjacent light spots is 30 um, and the grid line light spots are arranged in an array;

[0068] Among them, the diameter a of the light spot in the Pad point area is 30 μm, the distance b between the centers of two adjacent light spots is 26.25 um, the distance c between the centers of two light spot units is 82.5 um, and the Pad point light spots are arranged in an array;

[0069] c. Perform low-power ultrasonic cleaning on the grooved solar cell in the second cleaning solution; wherein, the second cleaning solution is an aqueous solution of hydrofluoric acid, its mass fraction is 0.5%, the temperature of the ultrasonic wave is 40 °C; the time of the ultrasonic wave is 30 s; the power of the ultrasonic wave is 90 W.

[0070] Example 2

[0071] This example provides a laser grooving method, including the following steps:

[0072] a. Immerse the solar cell in the first cleaning solution for soaking and cleaning; wherein, the first cleaning solution is toluene, the cleaning treatment time is 120 s, and the treatment temperature is 25 °C;

[0073] b. Use a laser to groove the front side of the solar cell to form a dot matrix light spot;

[0074] Among them, the repetition frequency of the laser is 2500 KHZ, the single pulse energy of the laser is 0.3 μj, the power percentage of the laser is 40%, the beam type of the laser is a flat-top beam, and the laser used is an ultraviolet nanosecond laser;

[0075] Among them, the depth of all the light spots is 90 nm;

[0076] Among them, the diameter a of the light spot in the grid line area is 70 μm, the distance b between the centers of two adjacent light spots is 140 um, and the grid line light spots are arranged in a plum blossom pattern;

[0077] Among them, the diameter a of the light spot within the Pad point area is 70 μm, the distance b between the centers of two adjacent light spots is 70 μm, the distance c between the centers of two light spot units is 280 μm, and the Pad point light spots are arranged in a plum blossom pattern;

[0078] c. Perform low-power ultrasonic cleaning on the grooved cell in a second cleaning solution. Among them, the second cleaning solution is an aqueous solution of hydrofluoric acid, its mass fraction is 5%, the temperature of the ultrasonic cleaning is 25 °C; the time of the ultrasonic cleaning is 90 s; the power of the ultrasonic cleaning is 30 W.

[0079] Example 3

[0080] This example provides a laser grooving method, including the following steps:

[0081] a. Immerse and clean the cell in a first cleaning solution. Among them, the first cleaning solution is toluene, the cleaning treatment time is 70 s, and the treatment temperature is 30 °C;

[0082] b. Use a laser to groove the front side of the cell to form a dot matrix light spot;

[0083] Among them, the repetition frequency of the laser is 2000 KHZ, the single pulse energy of the laser is 0.5 μj, the power percentage of the laser is 25%, the beam type of the laser is a flat-top beam, and the laser used is an ultraviolet picosecond laser;

[0084] Among them, the depth of the light spot is 100 nm;

[0085] Among them, the diameter a of the light spot within the grid line area is 50 μm, the distance b between the centers of two adjacent light spots is 50 μm, and the grid line light spots are arranged in an array;

[0086] Among them, the diameter a of the light spot within the Pad point area is 50 μm, the distance b between the centers of two adjacent light spots is 50 μm, the distance c between the centers of two light spot units is 180 μm, and the Pad point light spots are arranged in an array;

[0087] c. Perform low-power ultrasonic cleaning on the grooved cell in a second cleaning solution. Among them, the second cleaning solution is an aqueous solution of hydrofluoric acid, its mass fraction is 3%, the temperature of the ultrasonic cleaning is 30 °C; the time of the ultrasonic cleaning is 60 s; the power of the ultrasonic cleaning is 60 W.

[0088] Example 4

[0089] The difference from Example 3 is that the distance b between the centers of adjacent light spots in the grid line area is 45 μm, and the rest is the same as Example 3.

[0090] Example 5

[0091] The difference from Example 3 is that the distance b between the centers of adjacent light spots in the gate line area is 105 um, and the rest is the same as in Example 3.

[0092] Example 6

[0093] The difference from Example 3 is that the distance b between the centers of adjacent light spots in the Pad point area is 35 um, and the distance c between the centers of two light spot units is 170 um, and the rest is the same as in Example 3.

[0094] Example 7

[0095] The difference from Example 3 is that the distance b between the centers of adjacent light spots in the Pad point area is 55 um, and the rest is the same as in Example 3.

[0096] Example 8

[0097] The difference from Example 3 is that the distance c between the centers of two light spot units is 140 um, and the rest is the same as in Example 3.

[0098] Example 9

[0099] The difference from Example 3 is that the distance c between the centers of two light spot units is 210 um, and the rest is the same as in Example 3.

[0100] Comparative Example 1

[0101] This comparative example provides a laser grooving method, including the following steps:

[0102] The difference from Example 3 is that the repetition frequency of the laser is 1000KHZ, and the rest is the same as in Example 3.

[0103] Comparative Example 2

[0104] This comparative example provides a laser grooving method, including the following steps:

[0105] The difference from Example 3 is that the repetition frequency of the laser is 3000KHZ, and the rest is the same as in Example 3.

[0106] Comparative Example 3

[0107] This comparative example provides a laser grooving method, including the following steps:

[0108] The difference from Example 3 is that the single pulse energy of the laser is 0.2 μj, and the rest is the same as in Example 3.

[0109] Comparative Example 4

[0110] This comparative example provides a laser grooving method, including the following steps:

[0111] The difference from Example 3 is that the single-pulse energy of the laser is 0.9 μJ, and the rest is the same as in Example 3.

[0112] Comparative Example 5

[0113] This comparative example provides a laser grooving method, including the following steps:

[0114] The difference from Example 3 is that the diameters of the light spots in the grid line area and the Pad point area are both 25 μm;

[0115] The distance b between the centers of two adjacent light spots in the Pad point area is 25 μm, and the distance c between the centers of two light spot units is 100 μm;

[0116] The rest is the same as in Example 3.

[0117] Comparative Example 6

[0118] This comparative example provides a laser grooving method, including the following steps:

[0119] The difference from Example 3 is that the diameters of the light spots in the grid line area and the Pad point area are both 75 μm;

[0120] In the grid line area, the distance b between adjacent light spot centers is 75 μm;

[0121] The rest is the same as in Example 3.

[0122] Test Example

[0123] Test samples: TOPCon cells prepared by the grooving methods in Examples 1-9, and TOPCon cells prepared by the grooving methods in Comparative Examples 1-6.

[0124] Test method: The test indicators are the welding tensile force of the cell and the cell efficiency. The welding tensile force refers to the peak value during the process of the puller breaking the welding point between the welding tape and the pad point, and the cell efficiency refers to the conversion efficiency value measured by testing the spliced cell strips into a complete cell in an IV tester.

[0125] The test results are shown in Table 1.

[0126] Table 1

[0127] Sample Welding Tensile Force (N) Cell Efficiency (%) Example 1 1.9 26.35 Example 2 2.1 26.31 Example 3 2.4 26.43 Example 4 1.2 26.19 Example 5 1.5 26.24 Example 6 1.7 26.21 Example 7 1.3 26.26 Example 8 1.3 26.28 Example 9 1.4 26.20 Comparative Example 1 0.9 26.16 Comparative Example 2 0.8 26.09 Comparative Example 3 1.0 26.13 Comparative Example 4 0.7 26.04 Comparative Example 5 0.6 26.06 Comparative Example 6 1.1 25.99

[0128] It can be seen from the data in Table 1 that the parameters in Examples 4-9 and Comparative Examples 1-6 are too high or too low, and their welding tensile forces and cell efficiencies are not good.

[0129] The present invention uses high-frequency low-pulse energy small light spot matrix laser grooving on the front side of the TOPCon solar cell to reduce the damage to the alumina passivation layer and improve the open voltage and efficiency of the cell.

[0130] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser grooving method, characterized in that: The laser grooving method comprises the following steps: Laser is used to groove the front of the cell to form a dot matrix spot; Wherein, the repetition frequency of the laser is 1500-2500KHZ, the single pulse energy of the laser is 0.3-0.8μj, and the diameter of the light spot is 30-70μm; The light spot arranged in the grid line area is a first light spot, and a plurality of evenly arranged first light spots are arranged in the grid line area; Adjacent first light spots are tangent to each other or have a spacing; The light spot set in the Pad point area is the second light spot, the second light spot is the central light spot, a number of second light spots are evenly distributed around the center of the central light spot, the central light spot and the second light spots around it are a light spot unit, and a number of evenly arranged light spot units are set in the Pad point area.

2. The laser grooving method according to claim 1, characterized in that: The power percentage of the laser is 10-40%.

3. The laser grooving method according to claim 1, characterized in that: The beam type of the laser is a flat-top beam.

4. The laser grooving method according to claim 3, characterized in that: The laser includes an ultraviolet picosecond laser or an ultraviolet nanosecond laser.

5. The laser grooving method according to claim 1, characterized in that: The depth of the light spot is 90-110 nm.

6. The laser grooving method according to claim 1, characterized in that: The distance between the centers of adjacent first light spots is 30-140 um.

7. The laser grooving method according to claim 1, characterized in that: The distance between the centers of adjacent first light spots is less than or equal to the diameter of the first light spot.

8. The laser grooving method according to claim 1, characterized in that: The arrangement form of the plurality of first light spots is an array arrangement or a plum blossom arrangement.

9. The laser grooving method according to claim 1, characterized in that: There are 6 second light spots evenly distributed around the center of the central light spot.

10. The laser grooving method according to claim 1, characterized in that: The distance between the centers of each adjacent second light spot is less than or equal to the diameter of the second light spot, and greater than or equal to 0.875 times the diameter of the second light spot.

11. The laser grooving method according to claim 1, characterized in that: Each adjacent light spot unit is tangent to or has a spacing therebetween.

12. The laser grooving method according to claim 1, characterized in that: The spacing between adjacent light spot units is less than or equal to the diameter of the second light spot.

13. The laser grooving method according to claim 1, characterized in that: The arrangement form of the plurality of light spot units is an array arrangement or a plum blossom arrangement.

14. The laser grooving method according to claim 1, characterized in that: Before laser grooving, the cells are cleaned for the first time.

15. The laser grooving method according to claim 14, characterized in that: The first cleaning includes: placing the battery cell in a first cleaning solution and soaking and cleaning it.

16. The laser grooving method according to claim 15, characterized in that: The first cleaning liquid includes at least one of toluene, methanol, acetone and ethanol.

17. The laser grooving method according to claim 16, characterized in that: The cleaning treatment time is 20-120s, and the treatment temperature is 25-40°C.

18. The laser grooving method according to claim 1, characterized in that: The slotted battery cells are cleaned a second time.

19. The laser grooving method according to claim 18, characterized in that: The second cleaning includes: placing the slotted battery cell into a second cleaning solution for immersion and cleaning.

20. The laser grooving method according to claim 19, characterized in that: The second cleaning solution is an aqueous solution of hydrofluoric acid, and its mass fraction is 0.5-5%.

21. The laser grooving method according to claim 20, characterized in that: During the second cleaning process, the battery cell is ultrasonically cleaned.

22. The laser grooving method according to claim 21, characterized in that: The power of ultrasound is 30-90W.

23. The laser grooving method according to claim 21, characterized in that: The ultrasonic temperature is 25-40°C, and the ultrasonic time is 30-90s.

24. Use of the laser grooving method according to any one of claims 1 to 23 in preparing TOPCon batteries.

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