Production method of battery piece

Abstract

The invention relates to a production method of a battery piece. The production method comprises the following steps: printing a grid line electrode on the battery piece; the grid line electrode is sintered; cutting the battery piece; forming a passivation layer on the cutting edge of the battery piece, wherein the passivation layer is provided with an extension part extending to the light receiving surface of the battery piece; a laser is applied to the extension portion. In the application, the laser is applied to the extension part to anneal the passivation layer, so that the passivation degree of the passivation layer to the cutting edge can be improved, the recombination of the produced battery piece at the cutting edge is further reduced, and the photoelectric conversion efficiency of the produced battery piece is improved.

Description

[0001] This application is a divisional application. The original application has the application number 202411506586.9 and the filing date is October 25, 2024. The entire contents of the original application are incorporated herein by reference. Technical Field

[0002] This application relates to the field of solar cell technology, and more particularly to a method for producing solar cells. Background Technology

[0003] Solar cells can directly convert solar radiation energy into electrical energy, mainly based on the photovoltaic effect of crystalline silicon. When the photons of sunlight are absorbed by the semiconductor crystalline silicon, electron-hole pairs are generated. When these electron-hole pairs reach the pn junction composed of p-type and n-type crystalline silicon, they are separated to both sides of the pn junction by the junction electric field. When an external load is connected, a photocurrent is formed, and electrical energy is output.

[0004] In recent years, with the rise of module technologies such as half-cut modules and shingled modules, it is necessary to cut the solar cells during module manufacturing. After cutting, the edges of the solar cells have defects and damage, which leads to increased recombination at the cut edges of the solar cells and affects the photoelectric conversion efficiency of the solar cells.

[0005] Existing technologies reduce damage caused by cell cutting by depositing passivation films at the cut edges of the cells, but the passivation effect of the deposited passivation films is limited, and the photoelectric conversion efficiency of solar cells remains low. Summary of the Invention

[0006] This application provides a method for producing solar cells, which is used to improve the photoelectric conversion efficiency of solar cells.

[0007] This application provides a method for producing battery cells, including: Print grid line electrodes on the solar cell; The gate electrode is sintered; Cut the battery cells; A passivation layer is formed at the cut edge of the battery cell, the passivation layer having an extension extending to the light-receiving surface of the battery cell; A laser is applied to the extension.

[0008] In one possible design, when applying a laser to the extension, multiple laser spots are arranged along the length direction of the passivation layer, and the multiple laser spots are tangent to or intersect with the extension.

[0009] In one possible design, a laser is applied to the extension while a voltage is applied to the gate electrode.

[0010] In one possible design, after the step of forming a passivation layer at the cut edge of the solar cell, the method for producing the solar cell further includes: While applying voltage to the gate electrode, the gate electrode is irradiated with a laser.

[0011] In one possible design, during the step of irradiating the grid line electrode with a laser, multiple laser spots are arranged along the length direction of the grid line electrode, and the multiple laser spots are tangential to or intersect with the grid line electrode.

[0012] In one possible design, in step: applying a laser to the extension, and / or, in step: irradiating the gate electrode with a laser, the power P of the laser satisfies: 2600W ≤ P ≤ 2800W.

[0013] In one possible design, the step of applying a voltage to the gate electrode includes: bringing a probe for applying the voltage abutting against the gate electrode.

[0014] In one possible design, the step is: when applying a voltage to the gate electrode, the applied voltage U satisfies: 15V≤U≤20V.

[0015] In one possible design, the length L of the extension satisfies: 1mm ≤ L ≤ 3mm.

[0016] In one possible design, the thickness d of the passivation layer satisfies: 45nm ≤ d ≤ 60nm.

[0017] In one possible design, the passivation layer completely covers the cut surface of the battery cell.

[0018] In this application, by applying a laser to the extension portion to anneal the passivation layer, the passivation degree of the passivation layer on the cutting edge can be improved, further reducing recombination of the produced solar cells at the cutting edge and improving the photoelectric conversion efficiency of the produced solar cells.

[0019] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0020] Figure 1 A flowchart illustrating the method for producing the battery cells provided in this application; Figure 2 A schematic diagram of the structure of a battery cell produced by the battery cell manufacturing method provided in this application; Figure 3 This is a schematic diagram of irradiating the gate electrode with a laser while applying a voltage to the gate electrode; Figure 4This is a schematic diagram of applying a voltage to the gate electrode while simultaneously irradiating the passivation layer with a laser.

[0021] Figure label: 1-Battery cell; 11-Gate line electrode; 111 - Main gate; 112-auxiliary gate; 12-Passivation layer; 2-Probe; 3-Laser emitting device.

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Detailed Implementation

[0023] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0024] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0025] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0026] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0027] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when it is mentioned that an element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0028] This application provides a method for producing a battery cell 1, such as... Figure 1As shown, the method for producing the solar cell 1 includes: S1: Print grid line electrodes 11 on the solar cell 1.

[0029] In this step, the grid electrodes 11 are printed onto the solar cell 1 using a screen printing process. Screen printing is a process in which a squeegee squeezes and deforms the screen, causing the paste to be applied onto the surface to be printed. The solar cell 1 can then supply power to the outside world through the grid electrodes 11.

[0030] S2: Sinter the grid electrode 11.

[0031] In this step, sintering dries the slurry on the cell 1, burns off the organic components in the slurry, and allows the grid electrode 11 to form an ohmic contact with the cell 1.

[0032] S3: Cut battery cell 1.

[0033] In this step, the solar cell 1 can be cut by mechanical cutting, laser cutting, etc., but the cut edges have defects and damage, which leads to an increase in the composite content of the produced solar cell 1 and a decrease in photoelectric conversion efficiency.

[0034] S4: A passivation layer 12 is formed at the cut edge of the battery cell 1.

[0035] In this step, the passivation layer 12 can reduce defects and damage at the cutting edge of the solar cell 1, reduce the recombination of the produced solar cell 1, and improve the photoelectric conversion efficiency of the produced solar cell 1. However, the deposited passivation layer 12 still has the problem of incomplete passivation and limited improvement in photoelectric conversion efficiency. The material of the passivation layer 12 can be at least one or more of silicon oxide, aluminum oxide, nickel oxide, and zinc oxide.

[0036] S5: Apply voltage and laser to the solar cell 1 to anneal the grid electrode 11 and the passivation layer 12.

[0037] In this step, by applying voltage and laser to the solar cell 1 to anneal the grid electrode 11, interdiffusion of metal and silicon between the grid electrode 11 and the solar cell 1 can be initiated, improving the ohmic contact between the grid electrode 11 and the solar cell 1 and reducing the contact resistance between the grid electrode 11 and the solar cell 1. Simultaneously, by applying voltage and laser to the solar cell 1 to anneal the passivation layer 12, the passivation degree of the passivation layer 12 on the cutting edge can be improved, reducing damage to the solar cell 1 at the cutting edge, thereby reducing recombination at the cutting edge of the produced solar cell 1 and improving the photoelectric conversion efficiency of the produced solar cell 1.

[0038] Furthermore, in existing technologies, voltage and laser are typically applied to the solar cell 1 after sintering the grid electrode 11 in step S2 and before cutting the solar cell 1 in step S3, to improve the ohmic contact between the grid electrode 11 and the solar cell 1. This solution, by applying voltage and laser to the solar cell 1 after forming the passivation layer 12 at the cut edge in step S4, simultaneously anneales both the grid electrode 11 and the passivation layer 12, saving the time spent repeatedly arranging equipment for applying voltage and laser. This improves the passivation degree of the passivation layer 12 while reducing the production time of the solar cell 1, thereby increasing the production efficiency of the solar cell 1.

[0039] In one specific implementation, such as Figure 2 and Figure 3 As shown, in step 1, where a passivation layer 12 is formed at the cut edge of the solar cell 1, the passivation layer 12 completely covers the cut surface of the solar cell 1 and extends to the surface adjacent to the cut surface of the solar cell 1. For ease of description, the portion of the passivation layer 12 extending to the light-receiving surface of the solar cell 1 is defined as the extension portion.

[0040] In this embodiment, such as Figure 2 and Figure 3 As shown, if the passivation layer 12 only covers the cut surface of the solar cell 1, the edge of the passivation layer 12 will be aligned with the edge of the cut surface, resulting in poor passivation of the cut surface by the passivation layer 12 and high recombination at that location in the produced solar cell 1. Therefore, extending a portion of the passivation layer 12 to the surface adjacent to the cut surface of the solar cell 1, i.e., providing an extension, can improve the passivation effect of the passivation layer 12 on the cut surface, reduce recombination in the produced solar cell 1, and thus improve the photoelectric conversion efficiency of the produced solar cell 1.

[0041] Specifically, such as Figure 2 As shown, the length L of the passivation layer 12 extending on the surface adjacent to the cut surface of the battery cell 1 satisfies: 1mm ≤ L ≤ 3mm, that is, the length L of the extension satisfies: 1mm ≤ L ≤ 3mm. For example, the length L can be: 1mm, 1.3mm, 1.5mm, 1.8mm, 2mm, 2.3mm, 2.5mm, 3mm, etc.

[0042] The length L of the extension should not be too long or too short. If the length L of the extension is too short (e.g., less than 1 mm), the passivation effect of the passivation layer 12 on the edge of the cut surface may be poor. If the length L of the extension is too long (e.g., longer than 3 mm), the passivation layer 12 may contact the sub-gate 112, affecting the connection between the sub-gate 112 and the solar cell 1. At the same time, the passivation layer 12 will increase the shading of the light-receiving surface of the solar cell 1, which will also reduce the photoelectric conversion efficiency of the solar cell 1. Therefore, the length L of the extension should be set within a reasonable range.

[0043] Specifically, such as Figure 3 As shown, the thickness d of the passivation layer 12 satisfies: 45nm ≤ d ≤ 60nm. For example, the specific thickness of the passivation layer 12 can be 45nm, 48nm, 50nm, 52nm, 54nm, 56nm, 58nm, 60nm, etc.

[0044] The thickness of the passivation layer 12 should not be too thick or too thin. If the passivation layer 12 is too thin (e.g., thinner than 45 nm), the passivation effect of the passivation layer 12 on the cutting edge will be poor, resulting in increased composite material and photoelectric conversion efficiency of the produced solar cell 1. If the passivation layer 12 is too thick (e.g., thicker than 60 nm), the time required to deposit the passivation layer 12 will increase, resulting in lower production efficiency of the solar cell 1. Therefore, the thickness of the passivation layer 12 should be selected within a reasonable range.

[0045] Optionally, the passivation layer is formed at the cut edge of the solar cell 1 by atomic layer deposition (ALD).

[0046] In one specific implementation, such as Figure 3 and Figure 4 As shown, the step of applying voltage and laser to the battery cell 1 to anneal the grid line electrode 11 and the passivation layer 12 includes: while applying voltage to the grid line electrode 11, irradiating the grid line electrode 11 and the passivation layer 12 with a laser.

[0047] Step S4: During the process of forming the passivation layer 12 at the cut edge of the cell 1, the required time is 1~3h and the process temperature is 240~260℃. Therefore, in addition to forming the passivation layer 12 at the cut edge of the cell 1, this step will also cause the contact resistance between the grid electrode 11 and the cell 1 to increase, and cause more defects to appear inside the cell 1.

[0048] Therefore, irradiating the grid electrode 11 with a laser will result in a very high charge carrier injection at the location of the grid electrode 11 on the solar cell 1. Under a certain voltage, a local high current density and instantaneous high temperature will be generated simultaneously at the contact interface between the grid electrode 11 and the solar cell 1, thereby inducing the interdiffusion of metal and silicon, improving the ohmic contact between the grid electrode 11 and the solar cell 1, and reducing the contact resistance between the grid electrode 11 and the solar cell 1. At the same time, the thermal effects of the laser on the grid electrode 11 and the voltage on the solar cell 1 can also reduce defects inside the solar cell 1, thereby reducing recombination inside the solar cell 1.

[0049] Similarly, applying voltage to the grid electrode 11 will generate a thermal effect at the cut edge of the cell 1. Under the combined action of temperature and laser, the crystallinity of the passivation layer 12 can be improved, thereby enhancing the passivation effect of the passivation layer 12 on the cut edge.

[0050] Understandably, the laser can be used to irradiate the gate electrode 11 first, and then the passivation layer 12, or vice versa. Furthermore, when two laser irradiation mechanisms are provided, both mechanisms can simultaneously irradiate the gate electrode 11 and the passivation layer 12 with laser light.

[0051] More specifically, the laser emitting device 3 is capable of emitting laser light that irradiates the grid electrode 11 or the passivation layer 12. The laser light emitted by the laser emitting device 3 forms light spots arranged in the same direction on the solar cell 1.

[0052] like Figure 3 As shown, in step 1, when the grid line electrode 11 is irradiated with a laser, multiple laser spots are arranged along the length direction of the grid line electrode 11, and the multiple laser spots are tangent to or intersect with the grid line electrode 11.

[0053] The diameter of the laser spot is generally smaller than the diameter of the grid electrode 11. Since the laser contains high energy, the laser spot can generate a high thermal effect at the grid electrode 11 of the solar cell 1 when it is tangent to or intersects with the grid electrode 11.

[0054] like Figure 4 As shown, in step 1, when the passivation layer 12 is irradiated with a laser, multiple laser spots are arranged along the length direction of the passivation layer 12, and the multiple laser spots are tangential to or intersect with the extension portion. The laser emitted by the laser emitting device 3 can conveniently irradiate the extension portion.

[0055] Similarly, when the laser spot is tangent to or intersects with the extension, a high thermal effect can be generated at the passivation layer 12 of the battery cell 1, and this thermal effect can affect the back surface of the battery cell 1 from the light-receiving surface.

[0056] Furthermore, in step 1, when the grid electrode 11 is irradiated with a laser, the laser power P satisfies the condition: 2600W ≤ P ≤ 2800W. For example, the laser power can specifically be: 2600W, 2630W, 2650W, 2680W, 2700W, 2730W, 2750W, 2780W, 2800W, etc.

[0057] The laser power should not be too high or too low. If the laser power is too high (e.g., greater than 2800W), the grid electrode 11 may be over-sintered, causing it to collapse to both sides, increasing the area of ​​obstruction to the solar cell 1, or causing the grid electrode 11 to shrink, increasing the contact resistance between the grid electrode 11 and the solar cell 1, thus reducing the photoelectric conversion efficiency of the produced solar cell 1. If the laser power is too low (e.g., less than 2600W), it may not effectively improve the contact between the grid electrode 11 and the solar cell 1, affecting the photoelectric conversion efficiency of the produced solar cell 1. Therefore, the laser power P should be selected within a reasonable range.

[0058] Similarly, in step 12, when the passivation layer 12 is irradiated with a laser, the laser power P satisfies the following condition: 2600W ≤ P ≤ 2800W. For example, the specific laser power can be: 2600W, 2630W, 2650W, 2680W, 2700W, 2730W, 2750W, 2780W, 2800W, etc.

[0059] The laser power should not be too high or too low. If the laser power is too high (e.g., greater than 2800W), it may damage the passivation layer 12, increasing recombination at the cutting edge of the solar cell 1 and thus reducing the photoelectric conversion efficiency of the produced solar cell 1. If the laser power is too low (e.g., less than 2600W), it may not improve the passivation effect of the passivation layer 12 or may only have a limited effect, affecting the photoelectric conversion efficiency of the produced solar cell 1. Therefore, the laser power P should be selected within a reasonable range.

[0060] Furthermore, the wavelength of the laser irradiating the gate electrode 11 can be 532nm or 1064nm, and the wavelength of the laser irradiating the passivation layer 12 can also be 532nm or 1064nm. When the laser wavelength is 532nm, the laser light is green; when the laser wavelength is 1064nm, the laser light is red.

[0061] In some specific embodiments, such as Figure 2 and Figure 3 As shown, the gate electrode 11 includes a main gate 111 and a sub-gate 112, and multiple sub-gates 112 are electrically connected to the main gate 111.

[0062] Step: Applying voltage to the gate electrode 11 includes: bringing the probe 2 for applying voltage into contact with the main gate 111.

[0063] In this step, probe 2, which is connected to the power supply, comes into contact with the gate line electrode 11, thereby applying a voltage to the gate line electrode 11. Since multiple sub-gates 112 are electrically connected to the main gate 111, probe 2 can achieve electrical connection with each sub-gate 112 by being electrically connected to the main gate 111.

[0064] The cross-sectional size of the main gate 111 is larger than that of the secondary gate 112, so the main gate can be identified more easily, and the probe 2 can more easily contact the gate line electrode 11 to apply voltage to it.

[0065] Preferably, the number of probes 2 is the same as the number of sub-grids 112 on the solar cell 1. Each probe 2 abuts against the position on the main grid 111 where it connects to the sub-grid 112, thereby facilitating the application of voltage to each sub-grid 112 and ensuring that the current and thermal effects generated by the probes 2 applying voltage to the solar cell 1 are more evenly distributed across the solar cell 1. It is understood that the number of probes 2 can also be less than the number of sub-grids 112 on the solar cell 1.

[0066] Furthermore, multiple probes 2 can be integrated onto a single probe array, facilitating simultaneous contact between multiple probes 2 and the gate electrode 11. Multiple probes 2 can all contact the same main gate 111, or they can contact different main gates 111 respectively.

[0067] In other embodiments, the grid line electrode 11 includes only the sub-grid 112 and does not include the main grid 111, that is, a gridless cell with only the sub-grid 112 and no main grid 111. For a gridless cell, the step of applying voltage to the grid line electrode 11 includes: contacting the probe 2 for applying voltage with the sub-grid 112.

[0068] Furthermore, when irradiating the gate electrode 11 with a laser, the voltage applied to the gate electrode 11 by the probe 2 can be the same as or different from the voltage applied to the gate electrode 11 by the probe 2 when irradiating the passivation layer 12 with a laser. Understandably, the voltage applied to the gate electrode 11 by the probe 2 can be adjusted within a reasonable range according to actual operating conditions, and the moving speed, power, and wavelength of the laser irradiation of the gate electrode 11 can also be adjusted within a reasonable range according to actual operating conditions.

[0069] Specifically, in step 1, when applying voltage to the gate electrode 11, the applied voltage U satisfies: 15V ≤ U ≤ 20V. The applied voltage U can be 15V, 16V, 16.5V, 17V, 18V, 18.5V, 19V, 20V, etc.

[0070] The voltage applied to the grid electrode 11 should not be too high or too low. If the applied voltage is too high (e.g., greater than 20V), the temperature of the cell 1 will easily become too high, and the grid electrode 11 will be over-sintered. In this case, the grid electrode 11 will collapse to both sides, increasing the shading area of ​​the cell 1, or the grid electrode 11 will shrink, increasing the contact resistance between the grid electrode 11 and the cell 1, thus reducing the photoelectric conversion efficiency of the produced cell 1. If the applied voltage is too low (e.g., greater than 15V), the thermal effect of the voltage on the cell 1 will be limited, the temperature of the cell 1 will be low, and it will be difficult to improve the ohmic contact between the grid electrode 11 and the cell 1, and it will also be difficult to improve the passivation effect of the passivation layer 12 on the cut edges. Therefore, the voltage applied to the grid electrode 11 should be set within a reasonable range.

[0071] In the above embodiments, the battery cell 1 can be one of PERC (Passivated Emitter and Rear Cell), PERT (Passivated Emitter and Rear Totally-diffused cell), TOPCON (Tunnel Oxide Passivated Contact), or HJT (Heterojunction Technology).

[0072] In this application, by forming a passivation layer 12 at the cut edge of the solar cell 1, and then applying voltage to the grid electrode 11 while irradiating the grid electrode 11 and the passivation layer 12 with a laser, the ohmic contact between the grid electrode 11 and the solar cell 1 can be improved, the contact resistance between the grid electrode 11 and the solar cell 1 can be reduced, and the crystallinity of the passivation layer 12 can be improved. This enhances the passivation effect of the passivation layer 12 on the cut edge, thereby increasing the photoelectric conversion efficiency of the solar cell 1 produced in this way by 0.05% compared to the photoelectric conversion efficiency of the existing solar cell 1, and increasing the power of the photovoltaic module assembled from the solar cell 1 by 1W.

[0073] 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 for producing battery cells, characterized in that, The method for producing the battery cell (1) includes: Grid line electrodes (11) are printed on the solar cell (1). The gate electrode (11) is sintered; Cut the battery cell (1); A passivation layer (12) is formed at the cut edge of the battery cell (1), and the passivation layer (12) has an extension extending to the light-receiving surface of the battery cell; A laser is applied to the extension.

2. The method for producing battery cells according to claim 1, characterized in that, In the step of applying a laser to the extension, multiple laser spots are arranged along the length direction of the passivation layer (12), and the multiple laser spots are tangent to or intersect with the extension.

3. The method for producing battery cells according to claim 1, characterized in that, A laser is applied to the extension while a voltage is applied to the gate electrode (11).

4. The method for producing battery cells according to claim 1, characterized in that, Step: After forming a passivation layer (12) on the cut edge of the battery cell (1), the method for producing the battery cell (1) further includes: While applying voltage to the gate electrode (11), the gate electrode (11) is irradiated with a laser.

5. The method for producing battery cells according to claim 4, characterized in that, In the step of irradiating the grid line electrode (11) with a laser, multiple laser spots are arranged along the length direction of the grid line electrode (11), and the multiple laser spots are tangent to or intersect with the grid line electrode (11).

6. The method for producing battery cells according to claim 4, characterized in that, In step: applying laser to the extension, and / or, in step: irradiating the grid electrode (11) with laser, the power P of the laser satisfies: 2600W≤P≤2800W.

7. The method for producing a battery cell according to any one of claims 3-6, characterized in that, Step: Applying voltage to the gate electrode (11) includes: bringing a probe (2) for applying voltage into contact with the gate electrode (11).

8. The method for producing a battery cell according to any one of claims 3-6, characterized in that, Step: When applying voltage to the gate electrode (11), the applied voltage U satisfies: 15V≤U≤20V.

9. The method for producing a battery cell according to claim 1, characterized in that, The length L of the extension satisfies: 1mm≤L≤3mm.

10. The method for producing a battery cell according to claim 1, characterized in that, The thickness d of the passivation layer (12) satisfies: 45nm≤d≤60nm.

11. The method for producing a battery cell according to claim 1, characterized in that, The passivation layer (12) completely covers the cut surface of the battery cell (1).

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