Method for cutting battery cells and half-cell battery cells

Abstract

The application provides a cutting method of a battery piece and a half-piece battery piece. The battery piece comprises opposite first and second surfaces. A first cutting line is located on the first surface, and a second cutting line is located on the second surface. The projection of the first cutting line on the second surface overlaps the second cutting line. The method comprises the following steps: preheating the position of the first cutting line; performing laser scanning on the position of the first cutting line of the preheated battery piece; and performing cooling on the position of the second cutting line of the scanned battery piece by using a cooling process, so that the cooled battery piece is cracked to obtain a half-piece battery piece. The application solves the problem that, in the process of preparing a half-piece battery by using the existing laser scribing technology, the thermal damage of the surface and the cross section of a silicon piece caused by laser action seriously affects the transmission efficiency of carriers, and further affects the overall performance of the battery.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more specifically, to a method for cutting a battery cell and a half-cell battery cell. Background Technology

[0002] In the currently known half-cell battery fabrication technology, the temperature rise along the laser scanning path and the uneven temperature field on the silicon wafer, in turn, generate thermal stress due to the temperature gradient. When the generated tensile stress reaches the fracture limit of the silicon material, the silicon wafer stably cracks, achieving the purpose of cutting. The main method utilizes high-power thermal cracking laser heating and heat conduction from inside the battery to the back of the battery to provide a temperature gradient field to form thermal stress. The temperature difference between the upper and lower surfaces should reach the range of 150°-250°. Since the (100), (110), and (111) crystal planes of silicon material are the main fracture surfaces, and the fracture toughness of the three is relatively small, when crack-controlled laser cutting is performed, overall, under the action of thermal stress, the material cracks along the laser scanning direction. Locally, the thermal stress exceeds the corresponding fracture strength in all three crystal planes, resulting in regular ripples on the fracture surface. The generation of these ripples greatly affects the contour smoothness and surface roughness of the silicon wafer fracture surface, significantly impacting the composite density at this location and the subsequent passivation film formation effect. Therefore, it is necessary to address this issue through certain methods.

[0003] In the current laser scribing technology, the high-power laser causes thermal damage to the surface and cross-section during the cutting process, which affects the recombination density and carrier transport effect of the battery, resulting in a decrease in the open voltage and fill factor. Summary of the Invention

[0004] The main objective of this application is to provide a method for cutting solar cells and a half-cell solar cell, in order to solve the problem that in the process of preparing half-cell solar cells using existing laser scribing technology, the thermal damage to the surface and cross-section of the silicon wafer caused by laser action seriously affects the carrier transport efficiency, thereby affecting the overall performance of the cell.

[0005] To achieve the above objectives, according to one aspect of this application, a method for cutting a battery cell is provided. The battery cell includes a first surface and a second surface opposite to each other, a first cutting line located on the first surface, and a second cutting line located on the second surface. The projection of the first cutting line on the second surface overlaps with the second cutting line. The method includes: preheating the location of the first cutting line; performing laser scanning on the location of the first cutting line of the preheated battery cell; and using a cooling process to cool the location of the second cutting line of the scanned battery cell, so that the cooled battery cell cracks to obtain a half-cell.

[0006] Optionally, preheating the location of the first cutting line includes: using a heating device to preheat the location of the first cutting line at a temperature of 80°C to 90°C; and using a cooling process to cool the location of the second cutting line of the scanned solar cell, including: using a cooling device to cool the location of the second cutting line of the scanned solar cell at a temperature of -10°C to 10°C, so that the cooled solar cell forms a temperature gradient field in a predetermined direction, wherein the predetermined direction represents at least one of the three crystal orientations corresponding to the solar cell.

[0007] Optionally, laser scanning is performed on the location of the first cutting line of the preheated battery cell, including: using a laser with a laser power of 300W~600W, a laser frequency of 50Khz~200Khz, a scanning speed of 500mm / s~800mm / s, and a circular spot diameter of 1mm~2mm to scan the location of the first cutting line of the preheated battery cell.

[0008] Optionally, before preheating the location of the first cutting line, the method further includes: laser grooving both ends of the first cutting line to form end grooves.

[0009] Optionally, laser grooving is performed on both ends of the first cutting line, including: using a laser with a laser power of 30W~100W and a laser frequency of 50Khz~200Khz to groove both ends of the first cutting line.

[0010] Optionally, laser scanning is performed on the position of the first cutting line of the preheated battery cell, including: laser scanning is performed on the position of the first cutting line after preheating according to a first incident angle, wherein the first incident angle represents the angle between the scanning laser and the first surface; laser grooving is performed on both ends of the first cutting line, including: laser grooving is performed on both ends of the first cutting line according to a second incident angle, wherein the second incident angle represents the angle between the grooving laser and the first surface, and the first incident angle and the second incident angle are the same.

[0011] Optionally, preheating the location of the first cutting line includes: controlling a heating device to preheat the location of the first cutting line according to a heating angle, wherein the heating angle represents the angle between the heating device and the first surface, and the heating angle is the same as the first incident angle.

[0012] Optionally, a cooling process is used to cool the location of the second cutting line of the scanned battery cell, including: controlling a cooling device to cool the location of the second cutting line of the scanned battery cell according to a cooling angle, wherein the cooling angle represents the angle between the cooling device and the second surface, and the cooling angle is the same as the heating angle.

[0013] Optionally, laser grooving is performed on both ends of the first cutting line, including: using a red nano laser to laser groove both ends of the first cutting line.

[0014] According to another aspect of this application, a half-cell battery is provided, which is prepared by any of the battery cell cutting methods described above, wherein the depth of the cross-sectional crack of the half-cell battery is 0.1 μm to 0.5 μm, and the direction of the depth is perpendicular to the cross-section of the half-cell battery.

[0015] By applying the technical solution of this application, the position of the first cutting line is first preheated, then the position of the first cutting line of the preheated cell is laser scanned, and finally the position of the second cutting line of the scanned cell is cooled using a cooling process, so that the cooled cell cracks to obtain half a cell. Compared to existing laser scribing techniques, which suffer from severe thermal damage to the silicon wafer surface and cross-section caused by laser action during half-cell cell fabrication, significantly impacting carrier transport efficiency and thus overall cell performance, this application employs a preheating process (i.e., preheating the location of the first cutting line) before laser scanning of the cell using a thermally cracking laser. This preheats the first surface of the cell, allowing for the use of a lower-power laser during subsequent scanning. After laser scanning, a cooling process is employed to cool the back side (second surface) of the cell, causing it to crack into half-cells. By combining front-side preheating and back-side cooling, and by altering the external process temperature to create a temperature gradient field, the thermally cracking laser power is reduced, minimizing thermal damage to the cell surface and thus improving carrier transport efficiency and cell performance. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0017] Figure 1 A schematic flowchart of a method for cutting a battery cell according to an embodiment of this application is shown.

[0018] Figure 2A schematic diagram of the structure of a battery cell according to an embodiment of this application is shown;

[0019] Figure 3 A front view schematic diagram of a preheating structure of a battery cell using a heating device, according to an embodiment of this application, is shown.

[0020] Figure 4 A front view schematic diagram of a cooling device for cooling battery cells according to an embodiment of this application is shown;

[0021] Figure 5 A schematic diagram of a half-cell battery obtained by cutting a battery cell according to an embodiment of this application is shown.

[0022] Figure 6 A schematic diagram of a slotted structure for a battery cell is shown according to an embodiment of this application.

[0023] The above figures include the following reference numerals:

[0024] 10. Solar cell; 101. First surface; 102. Second surface; 11. First cutting line; 12. Second cutting line; 13. Hollowed-out platform; 14. Heating equipment; 15. Cooling equipment; 16. Half solar cell; 103. End groove. Detailed Implementation

[0025] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be an intermediate element present. Furthermore, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element via a third element.

[0028] As described in the background section, in the process of preparing a half-cell battery, the existing laser scribing technology causes thermal damage to the surface and cross-section of the silicon wafer due to the laser action, which seriously affects the carrier transport efficiency and thus the overall performance of the battery. In order to solve the above problems, the embodiments of this application provide a method for cutting a battery cell and a half-cell battery cell.

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0030] Figure 1 This is a flowchart of a method for cutting battery cells according to an embodiment of this application. Figures 2 to 6 As shown, the battery cell 10 includes a first surface 101 and a second surface 102 opposite to each other. A first cutting line 11 is located on the first surface 101, and a second cutting line 12 is located on the second surface 102. The projection of the first cutting line 11 onto the second surface 102 overlaps with the second cutting line 12. Figure 1 As shown, the method includes the following steps:

[0031] Step S101, as follows Figure 2 and Figure 3 As shown, the position where the first cutting line 11 is located is preheated;

[0032] Step S102: Perform laser scanning on the location of the first cutting line of the preheated battery cell.

[0033] Step S103, as follows Figure 2 , Figure 4 and Figure 5 As shown, a cooling process is used to cool the location of the second cutting line 12 of the scanned battery cell 10, so that the cooled battery cell 10 cracks to obtain a half battery cell 16.

[0034] In this embodiment, the position of the first cutting line is first preheated, then the position of the first cutting line of the preheated battery cell is laser scanned, and finally the position of the second cutting line of the scanned battery cell is cooled using a cooling process, so that the cooled battery cell cracks to obtain half a battery cell. Compared to existing laser scribing techniques, which suffer from severe thermal damage to the silicon wafer surface and cross-section caused by laser action during half-cell cell fabrication, significantly impacting carrier transport efficiency and thus overall cell performance, this application employs a preheating process (i.e., preheating the location of the first cutting line) before laser scanning of the cell using a thermally cracking laser. This preheats the first surface of the cell, allowing for the use of a lower-power laser during subsequent scanning. After laser scanning, a cooling process is employed to cool the back side (second surface) of the cell, causing it to crack into half-cells. By combining front-side preheating and back-side cooling, and by altering the external process temperature to create a temperature gradient field, the thermally cracking laser power is reduced, minimizing thermal damage to the cell surface and thus improving carrier transport efficiency and cell performance.

[0035] Specifically, the coverage width of the preheating and cooling zones on the solar cell is greater than the radiation width of the laser scan, and the direction of the width is perpendicular to the thickness of the solar cell.

[0036] In one optional embodiment, preheating the location of the first cutting line includes: preheating the location of the first cutting line at a temperature of 80°C to 90°C using a heating device; and cooling the location of the second cutting line of the scanned solar cell using a cooling process, including: cooling the location of the second cutting line of the scanned solar cell at a temperature of -10°C to 10°C using a cooling device, so that the cooled solar cell forms a temperature gradient field in a predetermined direction, wherein the predetermined direction represents at least one of the three crystal orientations corresponding to the solar cell. In this embodiment, by controlling the preheating and cooling temperatures, the temperature gradient inside the solar cell can be precisely adjusted, thereby further guiding the crack to develop along the predetermined direction and improving the cutting accuracy of the half-cell solar cell.

[0037] Specifically, a preheating process of 80°C to 90°C can be performed in front of the energy center of the thermal cracking laser (i.e., near the first cutting line) using spraying or other heating methods. Other heating methods can include infrared preheating, laser preheating, hot air preheating, etc., and this application does not impose specific limitations on them.

[0038] Specifically, a rear cooling platform can be used for cooling, or water cooling, air cooling, gas cooling, etc. can be used. This application does not impose any specific restrictions on this.

[0039] Specifically, such as Figure 3 and Figure 4 As shown, a hollow platform 13 is provided, and the upper surface of the hollow platform 13 has a hollow portion; as Figure 3 As shown, during preheating, the battery cell 10 can be placed inside the hollow platform, with the position of the first cutting line (not shown) on the first surface 101 corresponding to the hollow portion. The heating device 14 is then placed on top of the hollow platform 13 to preheat the position of the first cutting line. Figure 4 As shown, during cooling, the position of the second cutting line (not shown) on the second surface 102 is aligned with the hollowed-out portion, and the cooling device 15 is placed on the upper part of the hollowed-out platform 13 to cool the position where the second cutting line is located.

[0040] According to some exemplary embodiments of this application, laser scanning is performed on the location of the first cutting line of the preheated battery cell, including: scanning the location of the first cutting line of the preheated battery cell using a laser with a laser power of 300W~600W, a laser frequency of 50kHz~200kHz, a scanning speed of 500mm / s~800mm / s, and a circular spot diameter of 1mm~2mm. In this embodiment, by optimizing the laser parameters, efficient and precise cutting can be further achieved, while further reducing the thermal impact area of ​​the thermal cracking laser on the battery cell, further avoiding thermal damage, and improving the yield and reliability of half-cell batteries.

[0041] Specifically, thermal cracking laser refers to the laser used to scan preheated solar cells.

[0042] In other embodiments, before preheating the location of the first cutting line, the method further includes: as follows: Figure 6 As shown, laser grooving is performed on both ends of the first cutting line (not shown) to form end grooves 103. In this embodiment, by pre-forming end grooves at both ends of the cutting line, the starting position of the crack can be guided, making the crack develop more stably along the predetermined path, further improving the cutting accuracy and the quality of the half-cell.

[0043] Specifically, the two ends of the first cutting line are the two endpoints along the extension direction of the first cutting line.

[0044] Specifically, such as Figure 6As shown, the groove depth of the end groove 103 is 30% to 50% of the thickness of the battery cell 10. The length of the end groove 103 in the first direction is 1.2 mm to 2 mm, and the length of the end groove 103 in the second direction is 0.5 mm to 1.5 mm. The first direction is perpendicular to the thickness of the battery cell 10, and the second direction is perpendicular to the thickness of the battery cell 10. The first direction and the second direction are perpendicular to each other.

[0045] According to some other exemplary embodiments of this application, laser grooving is performed on both ends of the first cutting line, including: using a laser with a power of 30W to 100W and a frequency of 50kHz to 200kHz to groove both ends of the first cutting line. In this embodiment, by controlling the laser power and frequency, it can be ensured that the formation of the end grooves will not damage the battery cell or affect the subsequent cutting process, thus ensuring the continuity and stability of the cutting.

[0046] In some alternative embodiments of this application, laser scanning is performed on the location of the first cutting line on the preheated battery cell, including: laser scanning the location of the preheated first cutting line at a first incident angle, wherein the first incident angle represents the angle between the scanning laser and the first surface; laser grooving is performed on both ends of the first cutting line, including: laser grooving both ends of the first cutting line at a second incident angle, wherein the second incident angle represents the angle between the grooving laser and the first surface, and the first incident angle and the second incident angle are the same. In this embodiment, the first incident angle and the second incident angle are the same. By setting the same incident angle, it can be ensured that the direction of the force exerted by the laser beam on the battery cell is consistent, which helps to further form a uniform thermal stress distribution.

[0047] Specifically, the second incident angle is 30°~60°.

[0048] In some alternative embodiments of this application, preheating the location of the first cutting line includes: controlling the heating device to preheat the location of the first cutting line at a heating angle, wherein the heating angle represents the angle between the heating device and the first surface, and the heating angle is the same as the first incident angle. In this embodiment, setting the preheating angle and the laser cutting angle to be the same allows preheating and laser cutting to synergize in the direction of energy action. The thermal energy during preheating and the subsequent laser energy act in the same direction on the solar cell, which can more efficiently utilize the temperature gradient generated by preheating, promote the precise propagation of cracks along the predetermined direction of the laser cutting path, and reduce the generation of cracks in unexpected directions. Preheating and laser cutting are performed at the same angle, which allows for more precise control of the cutting process. The consistency between the temperature gradient and the laser energy direction helps to ensure the controllability of cracks and the cutting accuracy, avoiding inconsistent crack directions caused by angle differences, thereby further improving the predictability of cutting and the stability of the process.

[0049] In other embodiments, a cooling process is used to cool the location of the second cutting line on the scanned battery cell. This includes controlling a cooling device to cool the location of the second cutting line on the scanned battery cell at a cooling angle. The cooling angle represents the angle between the cooling device and the second surface, and the cooling angle is the same as the heating angle. In this embodiment, by setting the cooling angle to be the same as the heating angle, a directional temperature gradient field can be formed on the front and rear surfaces of the battery cell. This temperature gradient field is established along the direction of the laser cutting path, which helps to precisely control the crack propagation direction, ensuring that the crack develops along the preset cutting line, and further reducing the generation of unexpected cracks.

[0050] Specifically, if the cooling method is gas cooling, then the cooling angle is the angle between the outlet direction of the cooling device and the second surface.

[0051] Specifically, the angles of the thermal cracking laser and the preheating and cooling processes are all set to be consistent with the grooving angle. By increasing the temperature gradient in the predetermined direction, the silicon wafer (i.e., the solar cell) reaches the fracture strength first in the predetermined direction, so that the silicon wafer fractures and releases energy first in that direction. Ensuring that thermal stress is preferentially released in the desired direction can reduce the cross-sectional crack depth from 3μm~5μm in the existing process to 0.1μm~0.5μm, reducing cross-sectional cracks, greatly improving cross-sectional morphology, reducing lattice defects, reducing recombination density, improving carrier transport (increasing fill factor), improving cross-sectional flatness, enhancing cross-sectional passivation effect (increasing open-circuit voltage), which is beneficial for subsequent passivation film growth and reducing cross-sectional recombination.

[0052] Specifically, the depth of the cross-sectional crack in the half-cell of this application is 0.1μm~0.5μm, and the direction of the depth is perpendicular to the cross-section of the half-cell and perpendicular to the thickness of the cell.

[0053] Specifically, the battery cells in this application can be of various battery structures, including but not limited to Topcon structures.

[0054] Specifically, the fabrication process of the Topcon battery includes: providing an N-type silicon substrate; forming a P+ emitter on the upper surface of the silicon substrate; forming a tunneling layer on the lower surface of the silicon substrate; forming a passivation layer on the upper surface of the P+ emitter; forming an n+poly layer on the lower surface of the tunneling layer; forming a first antireflection film on the upper surface of the passivation layer; forming a second antireflection film on the lower surface of the n+poly layer; forming a plurality of spaced-apart first metal electrodes on the upper surface of the first antireflection layer; and forming a plurality of spaced-apart second metal electrodes on the lower surface of the second antireflection film. The first metal electrodes are electrically connected to the P+ emitter, and the second metal electrodes are electrically connected to the n+poly layer. The passivation layer is made of aluminum oxide, and both the first and second antireflection films are made of silicon oxide, silicon nitride, or silicon oxynitride. The passivation layer and the antireflection film can be a single-layer or multi-layer structure. For multi-layer structures, the materials of different layers can be different from each other, or some layers can be made of the same material but different from the materials of other layers. Specifically, the cutting can be performed after the N-type silicon substrate is provided, or it can be performed after the second metal electrode is formed (i.e., after the complete Topcon cell is fabricated). This application does not impose any specific restrictions on this. When cutting after the complete Topcon cell is fabricated, the cutting line needs to be set at the location where there is no metal electrode.

[0055] In summary, the preheating and cooling technology of this application helps to form a temperature gradient field to achieve the thermal stress release conditions required for wafer dicing, reducing the power of the thermal cracking laser and minimizing thermal damage. The directional formation of the temperature gradient field allows the silicon wafer to reach its fracture strength first along a specific direction, preferentially releasing thermal stress along that direction, reducing interface cracks, improving cross-sectional morphology, and facilitating passivation. It should be noted that existing solar cell cutting processes generally involve first grooving the wafer, then directly using a thermal cracking laser to scan the cutting position, and finally spraying coolant water mist along the same trajectory at the cutting position to complete the cutting. Table 1 shows a comparison of the performance parameters of half-cells obtained from existing cutting processes and the solar cell cutting method of this application.

[0056] Table 1

[0057]

[0058] Specifically, in the performance parameters in Table 1, PMPP is the photovoltaic module power, Voc is the open-circuit voltage, Isc is the short-circuit current, and FF is the fill factor.

[0059] In other embodiments, laser grooving is performed on both ends of the first cutting line, including: using a red nano laser to perform laser grooving on both ends of the first cutting line.

[0060] Specifically, finer-precision green lasers, green nano lasers, purple lasers, etc., can also be used for grooving, and this application does not impose specific restrictions on this.

[0061] To enable those skilled in the art to better understand the technical solution of this application, the implementation process of the battery cell cutting method of this application will be described in detail below with reference to specific embodiments.

[0062] This embodiment relates to a specific method for cutting a battery cell. The battery cell includes a first surface and a second surface opposite to each other. A first cutting line is located on the first surface, and a second cutting line is located on the second surface. The projection of the first cutting line on the second surface overlaps with the second cutting line. The method includes the following steps:

[0063] Step S1: Use a laser with a power of 30W~100W and a frequency of 50Khz~200Khz to groove both ends of the first cutting line;

[0064] Step S2: After grooving, use heating equipment to preheat the location of the first cutting line at a temperature of 80℃~90℃;

[0065] Step S3: Use a laser with a power of 300W~600W, a frequency of 50Khz~200Khz, a scanning speed of 500mm / s~800mm / s, and a circular spot diameter of 1mm~2mm to scan the position of the first cutting line of the preheated battery cell.

[0066] Step S4: Using a cooling device, the second cutting line of the scanned solar cell is cooled at a temperature of -10℃ to 10℃, so that the cooled solar cell cracks to obtain a half solar cell. The angles of laser scanning, preheating and cooling are all consistent with the grooving angle.

[0067] This application embodiment also provides a half-cell battery cell, which is prepared by any of the above-mentioned battery cell cutting methods. The depth of the cross-sectional crack of the half-cell battery cell is 0.1μm~0.5μm, and the direction of the depth is perpendicular to the cross-section of the half-cell battery cell.

[0068] In the above embodiments, the half-cell battery is prepared by a cell cutting method. In the cell cutting method, the position of the first cutting line is first preheated, then the position of the first cutting line of the preheated cell is laser scanned, and finally the position of the second cutting line of the scanned cell is cooled by a cooling process so that the cooled cell cracks to obtain a half-cell battery. Compared to existing laser scribing techniques, which suffer from severe thermal damage to the silicon wafer surface and cross-section caused by laser action during half-cell cell fabrication, significantly impacting carrier transport efficiency and thus overall cell performance, this application employs a preheating process (i.e., preheating the location of the first cutting line) before laser scanning of the cell using a thermally cracking laser. This preheats the first surface of the cell, allowing for the use of a lower-power laser during subsequent scanning. After laser scanning, a cooling process is employed to cool the back side (second surface) of the cell, causing it to crack into half-cells. By combining front-side preheating and back-side cooling, and by altering the external process temperature to create a temperature gradient field, the thermally cracking laser power is reduced, minimizing thermal damage to the cell surface and thus improving carrier transport efficiency and cell performance.

[0069] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0070] In the battery cell cutting method of this application, the position of the first cutting line is first preheated, then the position of the first cutting line of the preheated battery cell is laser scanned, and finally the position of the second cutting line of the scanned battery cell is cooled using a cooling process, so that the cooled battery cell cracks to obtain half a battery cell. Compared to existing laser scribing techniques, which suffer from severe thermal damage to the silicon wafer surface and cross-section caused by laser action during half-cell cell fabrication, significantly impacting carrier transport efficiency and thus overall cell performance, this application employs a preheating process (i.e., preheating the location of the first cutting line) before laser scanning of the cell using a thermally cracking laser. This preheats the first surface of the cell, allowing for the use of a lower-power laser during subsequent scanning. After laser scanning, a cooling process is employed to cool the back side (second surface) of the cell, causing it to crack into half-cells. By combining front-side preheating and back-side cooling, and by altering the external process temperature to create a temperature gradient field, the thermally cracking laser power is reduced, minimizing thermal damage to the cell surface and thus improving carrier transport efficiency and cell performance.

[0071] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method of cutting a battery sheet, characterized by, The battery piece includes opposite first and second surfaces, a first cutting line is located on the first surface, a second cutting line is located on the second surface, a projection of the first cutting line on the second surface overlaps with the second cutting line, and the method comprises: According to a second incidence angle, laser grooving is performed on both ends of the first cutting line to form end grooves, the second incidence angle represents the included angle between the grooving laser and the first surface, the groove depth of the end groove is 30%-50% of the thickness of the battery piece, and the second incidence angle is 30°-60°. A heating device is controlled to preheat the position where the first cutting line is located according to a heating angle, the heating angle represents the included angle between the heating device and the first surface, and the heating angle is the same as the first incidence angle. According to a first incidence angle, laser scanning is performed on the position where the first cutting line of the preheated battery piece is located, the first incidence angle represents the included angle between the scanning laser and the first surface, and the first incidence angle is the same as the second incidence angle. A cooling device is controlled to cool the position where the second cutting line of the scanned battery piece is located according to a cooling angle by using a cooling process, so that the battery piece after cooling is cracked to obtain a half battery piece, the cooling angle represents the included angle between the cooling device and the second surface, and the cooling angle is the same as the heating angle. The coverage width of the preheating area and the cooling area on the battery piece is greater than the radiation width of the laser scanning, and the width direction is perpendicular to the thickness direction of the battery piece.

2. The battery piece cutting method according to claim 1, wherein The preheating of the position where the first cutting line is located comprises preheating at a temperature of 80-90°C by using a heating device. The cooling of the position where the second cutting line of the scanned battery piece is located by using a cooling process comprises cooling at a temperature of -10-10°C by using a cooling device, so that the battery piece after cooling forms a temperature gradient field in a predetermined direction, and the predetermined direction represents at least one of the three crystal directions corresponding to the battery piece.

3. The method of cutting a battery sheet according to claim 1, wherein The laser scanning of the position where the first cutting line of the preheated battery piece is located comprises: The laser scanning of the position where the first cutting line of the preheated battery piece is located comprises using a laser with a laser power of 300-600W, a laser frequency of 50-200Khz, a scanning speed of 500-800mm / s, and a circular spot diameter of 1-2mm.

4. The cutting method of a battery cell according to claim 1, wherein The laser grooving of both ends of the first cutting line comprises: The laser grooving of both ends of the first cutting line comprises using a laser with a laser power of 30-100W and a laser frequency of 50-200Khz.

5. The method of cutting a battery slice according to claim 1, wherein The laser grooving of both ends of the first cutting line comprises using a red and green laser. The laser grooving of both ends of the first cutting line comprises using a red and green laser.

6. A half-cell wafer, characterized by, The half-cell piece is prepared by the cutting method of the cell piece in any one of claims 1 to 5, and the depth of the cross-section crack of the half-cell piece is 0.1 μm to 0.5 μm, and the direction of the depth is perpendicular to the direction of the cross-section of the half-cell piece.

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