A laser-assisted topcon cell double-sided processing system and method

Abstract

The application provides a kind of laser-assisted TOPCon cell double-sided processing system and method, system includes dual-wavelength laser source module, three-dimensional galvanometer system and vacuum reaction cavity, dual-wavelength laser source module emits laser of different wavelengths for simultaneously used in the sintering of front grid line and back etching of electric sheet, three-dimensional galvanometer system is arranged in vacuum reaction cavity;Vacuum reaction cavity is equipped with optical window, three-dimensional galvanometer system and dual-wavelength laser source module are coupled through optical window.The laser sintering front grid line of the application adopts axial oscillation scanning, expands the contact interface, improves the effective contact point density, reduces the contact resistance;Back annular etching pre-window, reduces the edge collapse, reduces the edge micro-crack density, reduces the recombination current;In situ passivation within 5s etching makes the interface dangling bond saturation, reduces the interface state density.The application avoids the physical damage of traditional mechanical cutting to doped layer, and maintains the integrity of doped structure through local processing of laser, finally realizes efficiency improvement.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic cell manufacturing technology, specifically relating to a laser-assisted TOPCon cell double-sided processing system and method. Background Technology

[0002] Photovoltaic cell technology is undergoing a transformation and upgrade from PERC (Exit-Passivated Cell) to TOPCon (Tunneling Oxide Passivated Contact). According to statistics from the China Photovoltaic Industry Association, newly built mass production lines in 2020 still dominated by PERC cells, with its market share increasing significantly from 65% in 2019 to 86.4%. As of 2023, despite the continuous emergence of new cell technologies, PERC technology still holds a dominant position in the photovoltaic industry due to its mature process system and relatively low manufacturing cost. However, the rapid growth period of PERC cell efficiency has ended, with laboratory efficiency approaching the theoretical limit of 24%, and the room for improvement in mass production efficiency is increasingly narrowing, typically stabilizing between 22.3% and 22.8%.

[0003] TOPCon technology has emerged as the most promising alternative due to its superior passivation contact characteristics. This technology involves fabricating an ultrathin tunneling oxide layer (SiOx, approximately 1.2 nm) on the back of the cell and depositing a heavily doped polycrystalline silicon layer (poly-Si, approximately 100 nm) on its surface, forming a highly efficient carrier-selective contact structure. This structure allows majority carriers to tunnel through the oxide layer via quantum tunneling, while simultaneously blocking minority carrier recombination, significantly reducing the surface recombination rate. Currently, the mass production efficiency of N-type TOPCon cells has reached 24.5%-25.1%, an absolute improvement of over 1.5% compared to PERC cells, making it a mainstream direction for photovoltaic industry upgrades.

[0004] Current high-efficiency battery technology faces multiple technical bottlenecks, mainly in the following three aspects:

[0005] The challenge of balancing contact resistance and passivation performance: The contact quality between the metal electrode and the semiconductor silicon wafer directly affects the fill factor and open-circuit voltage of the battery. Traditional high-temperature sintering processes, when forming ohmic contacts, tend to over-erode the passivation layer, leading to increased recombination current. While LECO (Laser Enhanced Contact Optimization) technology can significantly reduce contact resistance (ρc can be reduced to 1.8±0.58 mΩ·cm²) through laser-assisted sintering, this technology has been patented globally by Qcells through its acquisition of Cell Engineering GmbH, creating a serious patent barrier risk. In early 2025, Qcells initiated patent infringement lawsuits against several leading TOPCon companies, demanding the cessation of production and sales of related products.

[0006] The optical loss contradiction in bifacial structures: Bifacial cells need to balance efficiency on both sides, but if a full poly-Si passivation layer is used on the front side of a TOPCon cell, significant parasitic light absorption loss (approximately 1.5 mA / cm²) will occur. Traditional solutions use a partial window structure, but this requires complex masking and etching processes (such as photolithography or laser grooving), increasing the process cost by approximately 0.12 yuan / watt 410. The back side also suffers from the problem of excessively thick poly-Si layers leading to increased infrared light absorption, affecting the bifaciality (typically only 75%-80%).

[0007] Cutting process and edge recombination loss: Edge chipping and microcracks caused by mechanical cutting result in battery efficiency losses of ≥0.5% and a fragmentation rate of over 6%. Thermal damage from secondary cutting further exacerbates edge recombination and reduces open-circuit voltage. Traditional edge passivation requires separate PECVD deposition, which is separate from the main grid sintering process, leading to increased interface state density (>10¹¹eV⁻¹cm⁻²) and leakage current exceeding 0.5mA / cm². Summary of the Invention

[0008] The purpose of this invention is to provide a laser-assisted double-sided processing system for TOPCon batteries, thereby solving the aforementioned technical problems in the prior art.

[0009] Another objective of this invention is to provide a laser-assisted double-sided processing method for TOPCon batteries, which improves upon existing laser sintering technology and simultaneously utilizes annular etching for windowing and in-situ SiN... x Deposition improves battery efficiency.

[0010] Therefore, the technical solution provided by the present invention is as follows:

[0011] A laser-assisted TOPCon battery double-sided processing system includes a dual-wavelength laser source module, a three-dimensional galvanometer system, and a vacuum reaction chamber. The dual-wavelength laser source module simultaneously emits lasers of different wavelengths for sintering the grid lines on the front side of the battery sheet and etching the back side. The three-dimensional galvanometer system is located inside the vacuum reaction chamber.

[0012] The vacuum reaction chamber is provided with an optical window, and the three-dimensional galvanometer system and the dual-wavelength laser source module are coupled through the optical window. The three-dimensional galvanometer system includes a front scanning unit and a back control unit. The front scanning unit is used to receive the laser beam and control its reciprocating motion, and the back control unit is used to control the laser beam scanning path.

[0013] The vacuum reaction chamber is equipped with a temperature-controlled platform and a gas spray head.

[0014] A laser-assisted double-sided processing method for TOPCon batteries, employing a laser-assisted TOPCon battery double-sided processing system, includes the following steps:

[0015] Sintering is performed by axial periodic oscillating laser scanning on the front grid lines of the battery.

[0016] Simultaneously perform closed-loop annular laser etching on the cutting area on the back of the battery;

[0017] A passivation layer is deposited on the etched surface within 5 seconds after etching is completed.

[0018] The laser scanning path for the axial periodic oscillation of the grid lines on the front of the battery is a sinusoidal oscillation trajectory with a frequency of 8 Hz to 12 Hz and an oscillation scanning power of 18 W to 22 W.

[0019] The laser etching path on the back of the battery is a concentric double-ring structure, with the inner diameter being 2mm shorter than the side length of the battery and the ring spacing being 30μm±5%.

[0020] The wavelength of the axial periodic oscillation laser scanning of the grid lines on the front of the battery is 1064nm, and the amplitude is 10μm~20μm; the wavelength of the laser etching on the back of the battery is 355nm.

[0021] After the back of the battery is etched, a passivation layer is deposited within 0.5s. A mixture of SiH4 and NH3 gas is introduced through a gas spray head, and the deposition rate is greater than 40nm / s.

[0022] The depth of the closed-loop ring etching is 120 nm to 180 nm, and the linewidth is 25 μm to 35 μm.

[0023] SiN was deposited by introducing a mixed gas of SiH4 and NH3 during the deposition of the passivation layer. x Passivation layer, with a thickness of 150nm~200nm.

[0024] During axial periodic oscillating laser scanning, the laser reciprocates along the grid lines on the front of the battery within ±15μm. When performing closed-loop annular laser etching on the cutting area on the back of the battery, the diameter of the laser spot is no greater than 1cm.

[0025] The beneficial effects of this invention are as follows:

[0026] The laser-assisted TOPCon battery bifacial processing system provided by this invention provides dual-wavelength lasers through a dual-wavelength laser source module. Under the control of a three-dimensional galvanometer system, the two laser beams of different wavelengths oscillate and scan along the grid line axis with an amplitude of ±15μm and a frequency of 10kHz, respectively, inducing local micro-melting zones to achieve sintering of the front grid lines. The ultraviolet laser scans in a ring path (linewidth 30μm) to directly vaporize the polycrystalline silicon layer, forming a passivation window with an inward shrinkage of 20μm to achieve back-side etching. Within ≤5 seconds after laser etching, passivation deposition is performed through a vacuum reaction chamber to eliminate interface exposure time and achieve "zero-delay passivation".

[0027] The laser-assisted TOPCon battery double-sided processing system integrates laser sintering, back-side etching, and passivation deposition, which not only saves on the cost of cutting and passivation equipment, but also optimizes the base resistance and passivation quality.

[0028] This invention provides a laser-assisted double-sided processing method for TOPCon batteries. The laser sintering of the front-side grid lines employs axial oscillatory scanning to expand the contact interface, increase the effective contact point density, and reduce contact resistance. The back-side undergoes annular etching with pre-opening windows to avoid stress damage, reduce edge chipping, lower the density of microcracks at the edges, and reduce recombination current. In-situ passivation within 5 seconds of etching saturates the dangling bonds at the interface, reducing the interface state density. This invention avoids the physical damage to the doped layer caused by traditional mechanical cutting, while maintaining the integrity of the doped structure through localized laser processing, ultimately achieving improved efficiency. Attached Figure Description

[0029] Figure 1 This is a flowchart of the method of the present invention;

[0030] Figure 2 This is the timeline of passivation layer deposition after etching in this invention. Detailed Implementation

[0031] The following specific embodiments illustrate the implementation of the invention. Those skilled in the art can easily understand other advantages and effects of the invention from the content disclosed in this specification.

[0032] Exemplary embodiments of the invention are now described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention.

[0033] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0034] Example 1

[0035] This invention provides a laser-assisted double-sided processing system for TOPCon batteries, including a dual-wavelength laser source module, a three-dimensional galvanometer system, and a vacuum reaction chamber. The dual-wavelength laser source module simultaneously emits lasers of different wavelengths for sintering the grid lines on the front side of the battery sheet and etching the back side. The three-dimensional galvanometer system is located inside the vacuum reaction chamber.

[0036] The vacuum reaction chamber is provided with an optical window, and the three-dimensional galvanometer system and the dual-wavelength laser source module are coupled through the optical window. The three-dimensional galvanometer system includes a front scanning unit and a back control unit. The front scanning unit is used to receive the laser beam and control its reciprocating motion, and the back control unit is used to control the laser beam scanning path.

[0037] The dual-wavelength laser source module can simultaneously emit laser beams with wavelengths of 1064nm and 355nm. The 1064nm infrared laser beam is used for sintering the front-side grid lines of the battery, oscillating and scanning along the grid line axis with an amplitude of ±15μm and a frequency of 10kHz to induce local micro-melting zones (diameter ≤3μm) and form Ag-Si alloy lattices. The 355nm ultraviolet laser scans in a circular path, with photon energy (3.5eV) > Si-Si bond energy (2.3eV), directly vaporizing the polycrystalline silicon layer to form an inward passivation window. Within ≤5 seconds after laser etching, passivation deposition is performed through a vacuum reaction chamber, eliminating interface exposure time and achieving "zero-delay passivation". The front scanning unit controls the laser beam to reciprocate along the XY axis, while the back control unit controls the circular path of the laser beam.

[0038] The laser-assisted TOPCon battery double-sided processing system integrates laser sintering, back-side etching, and passivation deposition, which not only saves on the cost of cutting and passivation equipment, eliminates mechanical stress, and reduces edge microcracks, but also optimizes the base resistance and passivation quality.

[0039] Example 2

[0040] Based on Example 1, this example provides a laser-assisted TOPCon battery double-sided processing system, wherein the vacuum reaction chamber is equipped with a temperature-controlled stage and a gas spray head.

[0041] The temperature-controlled stage is used to place silicon wafers for processing on both the front and back sides. The temperature can be controlled between 20℃ and 80℃. The gas spray head is used to introduce SiH4 and NH3, and the inlet distance from the silicon wafer is ≤10cm.

[0042] The vacuum reaction chamber is also equipped with an aerosol isolation device, an inert gas inlet, and a residue suction port.

[0043] Example 3

[0044] This embodiment provides a laser-assisted double-sided processing method for TOPCon batteries, such as... Figure 1 As shown, it includes the following steps:

[0045] Sintering is performed by axial periodic oscillating laser scanning on the front grid lines of the battery.

[0046] Simultaneously perform closed-loop annular laser etching on the cutting area on the back of the battery;

[0047] A passivation layer is deposited on the etched surface within 5 seconds after etching is completed.

[0048] Furthermore, the axial periodic oscillation laser scanning path of the battery's front grid lines is a sinusoidal oscillation trajectory with a frequency of 8Hz to 12Hz and an oscillation scanning power of 18W to 22W. The spacing is 10μm, and the scanning speed is 2 m / s.

[0049] Furthermore, the laser etching path on the back of the battery is a concentric double-ring structure, with the inner diameter being 2mm shorter than the side length of the battery, and the ring spacing being 30μm±5%. The pre-opening window (inward design) of the ring laser etching on the back completely avoids mechanical cutting damage, and the chipping width is less than 5μm.

[0050] Furthermore, the wavelength of the axial periodic oscillation laser scanning of the grid lines on the front of the battery is 1064 nm, and the amplitude is 10 μm to 20 μm; the wavelength of the laser etching on the back of the battery is 355 nm.

[0051] Furthermore, after the back of the battery is etched, a passivation layer is deposited within 0.5s. A mixture of SiH4 and NH3 gas is introduced through a gas spray head, with a deposition rate greater than 40nm / s.

[0052] Furthermore, the depth of the closed-loop ring etching is 120nm~180nm, the linewidth is 25μm~35μm, and the inner window is 20μm (compatible with 1cm cutting channel).

[0053] Furthermore, a mixture of SiH4 and NH3 gas is introduced during the deposition of the passivation layer to deposit SiN. x A passivation layer, with a thickness of 150nm~200nm, is deposited at the fresh interface using laser etching PECVD technology, such as... Figure 2 As shown, SiH4 and NH3 are introduced within 5 seconds. The plasma activates the Si-H / NH bonds, which combine with dangling bonds to form a Si3N4 network. This saturates the dangling bonds at the interface, reducing the interface state density to <10¹. 0 eV⁻¹cm⁻². Among them, the spray head adopts turbulence control, with the gas flow velocity in the central region being greater than that in the edge region, with a ratio of 1.2:1, and a swirl angle of 15°, which improves the film thickness uniformity by ±2%.

[0054] Furthermore, during axial periodic oscillating laser scanning, the laser reciprocates along the grid lines on the front side of the battery within ±15μm. When performing closed-loop annular laser etching on the cutting area on the back side of the battery, the diameter of the laser spot is no greater than 1cm.

[0055] This invention simultaneously applies laser sintering and laser etching to the front and back of the battery. The front grid lines are laser-sintered using axial oscillation scanning to expand the contact interface, increase the effective contact point density, and reduce contact resistance (ρc < 2 mΩ·cm²). The back ring etching pre-opens windows to avoid stress damage, reduce edge chipping, lower the density of edge microcracks, and reduce recombination current (J0 < 5 fA / cm²). In-situ passivation within 5 seconds of etching saturates the dangling bonds at the interface, reducing the interface state density to < 10¹. 0 eV⁻¹cm⁻²

[0056] Compared to traditional step-by-step processes (LECO → dicing → PECVD), the solar cells prepared using this invention can reduce losses during the later dicing stage. The peak stress of mechanical dicing is >300 MPa, exceeding the fracture strength of ultra-polycrystalline silicon (250 MPa). Therefore, mechanical dicing inevitably generates cracks, leading to micro-cracks at the edges, and secondary laser-induced burns to the passivation layer, resulting in passivation failure and efficiency degradation. In this invention, the laser-etched heat-affected zone is <1 μm (355 nm cold etching), with a thermal stress <50 MPa, below the damage threshold; the recessed window buffer distance of 20 μm is greater than the crack propagation length (average 15 μm), thus achieving physical isolation protection.

[0057] Example 4

[0058] To further illustrate the effectiveness of the method of the present invention, this embodiment, based on Example 3, prepares a battery cell, and the specific process is as follows:

[0059] Step 1) Texturing: The silicon wafer is etched with an alkaline solution to form a pyramidal textural structure;

[0060] Step 2) Frontal boron diffusion: Surface diffusion is performed using a boron source;

[0061] Step 3) Backside etching: Remove the BSG layer wrapped around the backside and polish with alkaline solution;

[0062] Step 4) Preparation of tunneling oxide layer: A 1nm~2nm ultrathin silicon oxide layer is prepared by ALD;

[0063] Step 5) In-situ phosphorus doping of polycrystalline silicon: In-situ phosphorus doping of polycrystalline silicon is performed on the back side using LPCVD;

[0064] Step 6) Front etching: Etch away the polysilicon thin film and PSG layer deposited around the edges and front side, and perform RCA cleaning;

[0065] Step 7) Front-side alumina passivation: A front-side alumina film is deposited using ALD atomic deposition.

[0066] Step 8) Front and back films: Hydrogen passivation is performed on the front and back sides of the silicon wafer by chemical vapor deposition, and silicon nitride films are deposited on the surface;

[0067] Step 9) Printing and sintering;

[0068] Step 10) Simultaneously perform laser ring etching on the back side while laser sintering the front-side grid lines:

[0069] Laser sintering of front-side grid lines: 1064nm laser, axial oscillation scanning (amplitude ±15μm, frequency 10kHz, power 20W), contact resistance reduced to 1.8 mΩ·cm².

[0070] Backside laser ring etching: 355nm laser, concentric double ring path (inner diameter 2mm shorter than the side length of the battery, ring spacing 30μm, depth 150nm, line width 30μm), chipping width <5μm.

[0071] In-situ passivation: A SiH4 / NH3 mixed gas is introduced within 0.5 seconds after etching to deposit SiN. x Passivation layer (180 nm thick, deposition rate 45 nm / s), interface state density <10¹ 0 eV⁻¹cm⁻².

[0072] Comparative example:

[0073] Unlike Example 4, step 10) is laser sintering, while the other steps are the same.

[0074] The battery cells prepared in Example 4 and the comparative example were tested, and the results are shown in Table 1.

[0075] Table 1 Performance Parameters

[0076]

[0077] As shown in Table 1, the present invention achieves the following advantages through laser-assisted double-sided synchronous processing technology:

[0078] 1. Efficiency Improvement: The absolute value of conversion efficiency increased by 1.1% (26.16% vs 26.05%), mainly due to the reduction in contact resistance and composite current.

[0079] 2. Simplified process: Sintering, etching and passivation are completed in one step, saving equipment costs (reducing cutting and secondary passivation equipment).

[0080] 3. Enhanced reliability: Edge microcracks are reduced by 80%, and passivation quality is significantly improved (interface state density is reduced by an order of magnitude).

[0081] 4. Compatibility: Suitable for large-size silicon wafers (182 / 210mm), and the process parameters are compatible with existing TOPCon production lines.

[0082] The performance bottlenecks caused by mechanical cutting and passivation delays in traditional processes have been completely overcome. This invention provides an efficient and low-cost solution for the mass production of TOPCon batteries.

[0083] In summary, the laser-assisted TOPCon battery bifacial processing system provided by this invention provides dual-wavelength lasers through a dual-wavelength laser source module. Under the control of a three-dimensional galvanometer system, the two laser beams of different wavelengths oscillate and scan along the grid line axis with an amplitude of ±15μm and a frequency of 10kHz, respectively, inducing local micro-melting zones to achieve sintering of the front grid lines. Meanwhile, the ultraviolet laser scans in a ring path (linewidth 30μm) to directly vaporize the polycrystalline silicon layer, forming a passivation window with an inward shrinkage of 20μm to achieve back-side etching. Within ≤5 seconds after laser etching, passivation deposition is performed through a vacuum reaction chamber, eliminating interface exposure time and achieving "zero-delay passivation".

[0084] The laser-assisted TOPCon battery double-sided processing system integrates laser sintering, back-side etching, and passivation deposition, which not only saves on the cost of cutting and passivation equipment, but also optimizes the base resistance and passivation quality.

[0085] This invention provides a laser-assisted double-sided processing method for TOPCon batteries. The laser sintering of the front-side grid lines employs axial oscillatory scanning to expand the contact interface, increase the effective contact point density, and reduce contact resistance. The back-side undergoes annular etching with pre-opening windows to avoid stress damage, reduce edge chipping, lower the density of microcracks at the edges, and reduce recombination current. In-situ passivation within 5 seconds of etching saturates the dangling bonds at the interface, reducing the interface state density. This invention avoids the physical damage to the doped layer caused by traditional mechanical cutting, while maintaining the integrity of the doped structure through localized laser processing, ultimately achieving improved efficiency.

[0086] The examples above are merely illustrative of the invention and do not constitute a limitation on the scope of protection of the invention. Any design that is the same as or similar to the invention falls within the scope of protection of the invention.

Claims

1. A laser-assisted TOPCon cell double-side processing system, characterized in that: It includes a dual-wavelength laser source module, a three-dimensional galvanometer system, and a vacuum reaction chamber. The dual-wavelength laser source module emits lasers of different wavelengths simultaneously for sintering the front grid lines and etching the back side of the electrode sheet. The three-dimensional galvanometer system is located inside the vacuum reaction chamber. The vacuum reaction chamber is provided with an optical window, and the three-dimensional galvanometer system and the dual-wavelength laser source module are coupled through the optical window. The three-dimensional galvanometer system includes a front scanning unit and a rear control unit. The front scanning unit is used to receive the laser beam and control its reciprocating motion, and the rear control unit is used to control the laser beam scanning path. The dual-wavelength laser source module simultaneously emits a 1064nm wavelength laser beam and a 355nm wavelength laser beam. The 1064nm wavelength laser beam is used for sintering the front grid lines of the battery, oscillating and scanning up and down along the grid line axis with an amplitude of ±15μm and a frequency of 10kHz. The 355nm wavelength laser beam is used for back etching, scanning in a ring path to directly vaporize the polycrystalline silicon layer and form a passivation window with an inward shrinkage of 20μm. The vacuum reaction chamber is used for passivation deposition within ≤5 seconds after laser etching.

2. The laser-assisted TOPCon battery double-sided processing system according to claim 1, characterized in that: The vacuum reaction chamber is equipped with a temperature-controlled platform and a gas spray head.

3. A laser-assisted double-sided processing method for TOPCon batteries, characterized in that: The laser-assisted TOPCon battery double-sided processing system according to claim 1 or 2 includes the following steps: Sintering is performed by axial periodic oscillating laser scanning on the front grid lines of the battery. Simultaneously perform closed-loop annular laser etching on the cutting area on the back of the battery; A passivation layer is deposited on the etched surface within 5 seconds after etching is completed.

4. The laser-assisted double-sided processing method for TOPCon batteries according to claim 3, characterized in that: The laser scanning path for the axial periodic oscillation of the grid lines on the front of the battery is a sinusoidal oscillation trajectory with a frequency of 8 Hz to 12 Hz and an oscillation scanning power of 18 W to 22 W.

5. The laser-assisted double-sided processing method for TOPCon batteries according to claim 3, characterized in that: The laser etching path on the back of the battery is a concentric double-ring structure, with the inner diameter being 2mm shorter than the side length of the battery and the ring spacing being 30μm±5%.

6. The laser-assisted double-sided processing method for TOPCon batteries according to claim 3, characterized in that: The wavelength of the axial periodic oscillation laser scanning of the grid lines on the front of the battery is 1064 nm, and the amplitude is 10 μm ~ 20 μm; the wavelength of the laser etching on the back of the battery is 355 nm.

7. The laser-assisted double-sided processing method for TOPCon batteries according to claim 3, characterized in that: After the back of the battery is etched, a passivation layer is deposited within 0.5s. A mixture of SiH4 and NH3 gas is introduced through a gas spray head, with a deposition rate greater than 40nm / s.

8. The laser-assisted double-sided processing method for TOPCon batteries according to claim 3, characterized in that: The depth of the closed-loop ring etching is 120 nm ~ 180 nm, and the linewidth is 25 μm ~ 35 μm.

9. The laser-assisted double-sided processing method for TOPCon batteries according to claim 3, characterized in that: SiN is deposited by introducing a mixed gas of SiH4 and NH3 during deposition of the passivation layer X The passivation layer has a thickness of 150 nm to 200 nm.

10. A laser-assisted double-sided processing method for TOPCon batteries according to claim 3, characterized in that: During axial periodic oscillating laser scanning, the laser reciprocates along the grid lines on the front of the battery within ±15μm. When performing closed-loop annular laser etching on the cutting area on the back of the battery, the diameter of the laser spot is no greater than 1cm.

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