Battery edge passivation method and solar battery

Abstract

The invention relates to the technical field of solar cells, and mainly provides a cell edge passivation method and a solar cell. The battery edge passivation method comprises the steps that a whole battery is sliced to obtain a battery piece, and the battery piece is provided with a cutting face; spraying ultrapure water on the cutting surface of the battery piece to form a water film; and laser scanning is conducted on the water film, ultrapure water in the water film is ionized, hydrogen ions and oxygen ions are generated, and a silicon oxide layer is formed on the cutting face through the oxygen ions. According to the battery edge passivation method in the technical scheme, the conversion efficiency of the solar battery can be improved, the equipment investment cost is low, and the process is simple.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a cell edge passivation method and a solar cell. Background Art

[0002] With the popularization of cell slicing, shingling, and assembling technologies, the use of lasers to cut whole cells has gradually become the mainstream trend in the industry. However, after laser cutting, the cross section of the cell will be severely damaged by lasers, and there will be a large number of dangling bonds and defect states on the surface of the cross section, which will become effective recombination centers for carriers. A large number of carriers will recombine through interface defects, which will seriously reduce the conversion efficiency of solar cells.

[0003] In order to improve the problem of decreased battery efficiency caused by laser cutting, the following two solutions are mainly used in the existing technology: 1) Use a chemical solution containing an oxidant to contact the battery section, then irradiate it with an ultraviolet lamp, and then perform heat treatment to finally form a silicon oxide passivation layer; 2) Deposit an aluminum oxide dielectric film on the side of the cut battery cell. However, the first solution requires ultraviolet lamp irradiation equipment and heat treatment equipment, and the processing time is long, which is not conducive to industrial production and manufacturing; the second solution requires additional coating equipment and a coating of the battery cut surface, which requires an additional coating process, increases the process cost and energy consumption cost, and the process is complicated, which is not conducive to the cost reduction needs of industrialization.

[0004] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the invention

[0005] The present application provides a battery edge passivation method and a solar cell to solve or alleviate the above-mentioned technical problems. The battery edge passivation method in the technical solution of the present application can improve the conversion efficiency of the solar cell, and the equipment investment cost is low and the process is simple.

[0006] In a first aspect, an embodiment of the present application provides a battery edge passivation method, comprising: Slicing the whole battery to obtain a battery cell, wherein the battery cell has a cutting surface; Spraying ultrapure water on the cut surface of the battery cell to form a water film; The water film is subjected to laser scanning to ionize the ultrapure water in the water film to generate hydrogen ions and oxygen ions, and the oxygen ions are used to form a silicon oxide layer on the cutting surface.

[0007] Optionally, the conductivity of the ultrapure water is less than 2uS / cm.

[0008] Optionally, in the process of spraying the ultrapure water, the spraying pressure is 0.3-0.7 MPa, the spraying flow rate is 0.1-10 L / min, and the spraying time is 1-10 s.

[0009] Optionally, the thickness of the water film is 0.1 mm-5 mm.

[0010] Optionally, spraying ultrapure water on the cut surface of the battery cell comprises: using an atomizing spray device to spray the ultrapure water on the cut surface of the battery cell; Wherein, the distance between the nozzle of the atomizing spray device and the cutting surface is 10-50 mm.

[0011] Optionally, when performing the laser scanning, the laser pulse width is greater than or equal to 15 picoseconds (ps).

[0012] Optionally, when performing the laser scanning, the laser wavelength is 355nm-1064nm.

[0013] Optionally, when performing the laser scanning, the laser power is 50W-1000W.

[0014] Optionally, when performing the laser scanning, the spot area is 50 μm×50 μm-500 μm×500 μm.

[0015] Optionally, when performing the laser scanning, the laser pulse width is 15 picoseconds-1 nanosecond, the laser wavelength is 532-808nm, the laser power is 100-600W, and the spot area is 100μm×100μm-300μm×300μm.

[0016] In a second aspect, an embodiment of the present application provides a solar cell, comprising: a cell having a cut surface, and a silicon oxide layer located on the cut surface; Wherein, the preparation method of the silicon oxide layer comprises: Spraying ultrapure water on the cut surface of the battery cell to form a water film; The water film is subjected to laser scanning to ionize the ultrapure water in the water film to generate hydrogen ions and oxygen ions, and the silicon oxide layer is formed on the cutting surface using the oxygen ions.

[0017] Optionally, the silicon oxide layer has a thickness of 3-10 nm.

[0019] The above technical solution adopted in the embodiment of the present application may have the following advantages: In the embodiment of the present application, ultrapure water (DI) is first sprayed on the cut surface of the battery cell to form a water film, and then the water film is scanned by laser to ionize the ultrapure water in the water film to generate hydrogen ions (H + ) and oxygen ions (O2- ), hydrogen ions can repair the silicon dangling bonds on the surface of the cut surface, and oxygen ions can react with the silicon on the cut surface to form a silicon oxide layer (i.e., a passivation layer), thereby reducing the recombination center of the cut surface of the cell, ensuring the quality and performance of the edge of the cell, and improving the conversion efficiency of the solar cell. In addition, the passivation method does not require ultraviolet light irradiation equipment, heat treatment equipment, and coating equipment, etc. The equipment investment cost is low, the process is simple, the processing rhythm is fast, and it is conducive to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0021] Figure 1 is a flow chart of a battery edge passivation method according to an embodiment of the present application; Figure 2 is a schematic structural diagram of a battery stack according to an embodiment of the present application; Figure 3 It is a schematic diagram of the working principle of the atomizing spray device of an embodiment of the present application; Figure 4 It is a schematic diagram of the working principle of laser scanning in an embodiment of the present application.

[0022] Description of reference numerals: 10. Battery stack; 11. Battery cell; 20. Atomizing spray device; 30. Laser scanner. DETAILED DESCRIPTION

[0023] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. In the accompanying drawings, for clarity, the sizes of layers, regions, elements and their relative sizes may be exaggerated. Wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limitations on the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0024] like Figure 1 As shown, an embodiment of the present application provides a battery edge passivation method, comprising: S100: Slicing the entire battery to obtain a battery cell, wherein the battery cell has a cutting surface; S200: Spraying ultrapure water on the cut surface of the battery cell to form a water film; S300: The water film is laser scanned to ionize the ultrapure water in the water film, generate hydrogen ions and oxygen ions, and use the oxygen ions to form a silicon oxide layer on the cutting surface.

[0025] In the embodiment of the present application, ultrapure water (DI) is first sprayed on the cut surface of the battery cell to form a water film, and then the water film is scanned by laser to ionize the ultrapure water in the water film to generate hydrogen ions (H + ) and oxygen ions (O 2- ), hydrogen ions can repair the silicon dangling bonds on the surface of the cut surface, and oxygen ions can react with the silicon on the cut surface to form a silicon oxide layer (i.e., a passivation layer), thereby reducing the recombination center of the cut surface of the cell, ensuring the quality and performance of the edge of the cell, and improving the conversion efficiency of the solar cell. In addition, the passivation method does not require ultraviolet light irradiation equipment, heat treatment equipment, and coating equipment, etc. The equipment investment cost is low, the process is simple, the processing rhythm is fast, and it is conducive to industrial production.

[0026] Each step in the battery edge passivation method of the embodiment of the present application is described in detail below.

[0027] In step S100, a laser may be used to slice the entire battery to obtain a plurality of battery cells with cut surfaces (the number of battery cells may be 2 or more).

[0028] It should be noted that in step S100, laser is used to slice the whole cell so that the silicon at the edge of the silicon substrate is exposed. During the laser slicing process, the cut surface of the cell must be kept clean to avoid introducing impurities on the cut surface, which may affect the subsequent attachment of the water film. The whole cell is laser cut to form a half-piece (also called a half-piece), or a third-piece, a quarter-piece, ..., an Nth-piece, etc. The cell may be of regular shape or irregular shape.

[0029] In step S100, Figure 2 As shown, the battery stack 10 includes a plurality of battery cells 11 , and the battery stack 10 can be formed by stacking the plurality of battery cells 11 through a transmission device.

[0030] In step S200, Figure 3 As shown, an atomizing spray device 20 can be used to spray ultrapure water, and the distance between the nozzle of the atomizing spray device and the cut surface of the battery cell is 10-50mm (for example, 10mm, 20mm, 30mm, 40mm, 50mm), so that the ultrapure water is atomized and sprayed on the cut surface of the battery cell. The water is evenly distributed in the form of fine droplets, which is conducive to forming a water film with uniform thickness.

[0031] In some embodiments, the conductivity of ultrapure water is less than 2uS / cm. When the conductivity of ultrapure water is less than 2uS / cm, it indicates that there are no or a small amount of impurities in the ultrapure water, which prevents contamination of the silicon wafer. Specifically, the conductivity of ultrapure water can be 0.1uS / cm, 0.2uS / cm, 0.5uS / cm, 0.7uS / cm, 1uS / cm, 1.3uS / cm, 1.5uS / cm, 1.8uS / cm.

[0032] In some embodiments, when spraying ultrapure water, the spray pressure is 0.3-0.7MPa, the spray flow rate is 0.1-10L / min, and the spray time is 1-10s. When spraying ultrapure water, controlling the spray pressure, spray flow rate and spray time can ensure that the water film covers the entire cut surface with uniform thickness and stable water film. Specifically, the spray pressure can be 0.3MPa, 0.5MPa, 0.7MPa, the spray flow rate can be 0.1L / min, 1L / min, 3L / min, 5L / min, 8L / min, 10L / min, and the spray time is 1s, 3s, 5s, 8s, 10s.

[0033] In some embodiments, the thickness of the formed water film is 0.1 mm-5 mm. If the thickness of the water film is too small, even if the water in the water film is completely ionized, the oxygen ion concentration is difficult to reach the required concentration, affecting the formation of the subsequent silicon oxide layer; if the thickness of the water film is too large, the oxygen ion concentration after ionization is too saturated, resulting in a waste of resources. Specifically, the thickness of the water film can be 0.1 mm, 0.5 mm, 1 mm, 2 mm, 4 mm, or 5 mm.

[0034] In step S300, Figure 4 As shown, a laser scanner 30 is used to perform laser scanning on the water film on the cut surface of the battery cell 11. Since the instantaneous energy density of the laser scanning is very high, greater than 107W / mm 2 , ionizing the ultrapure water in the water film and generating a large amount of hydrogen ions (H + ) and oxygen ions (O 2- ), hydrogen ions can repair the silicon dangling bonds on the surface of the cut surface, and oxygen ions can react with the silicon on the cut surface to form a silicon oxide layer, forming a passivation layer, thereby reducing the recombination center of the cut surface and improving the conversion efficiency of the sliced ​​battery.

[0035] In some embodiments, in order to ensure that the scanning laser can directly vaporize the ultrapure water in the water film, the laser pulse width is greater than or equal to 15 picoseconds (ps) during laser scanning. Specifically, the laser pulse width can be 15ps, 30ps, 50ps, 70ps, 85ps, 100ps, 300ps, 500ps, or 1000ps.

[0036] In some embodiments, in order to ensure that the scanning laser can directly gasify the ultrapure water in the water film, when performing laser scanning, the laser wavelength can be adjusted to 355nm-1064nm, or the laser power can be adjusted to 50W-1000W. Specifically, the laser wavelength can be 355nm, 532nm, 650nm, 808nm, 905nm, 1064nm. Specifically, the laser power can be 50W, 100W, 200W, 300W, 400W, 500W, 600W, 700W, 800W, 900W, 1000W.

[0037] In some embodiments, when performing laser scanning, the spot area is 50μm×50μm-500μm×500μm, which can shorten the laser scanning time (for example, the laser scanning time is within 60s). In the laser scanning process, the laser can use DOE flat top light, and the spot shape can be square, rectangular or circular. Among them, the spot area can be 50μm×50μm, 100μm×100μm, 200μm×200μm, 300μm×300μm, 500μm×500μm.

[0038] In some embodiments, when performing laser scanning, the laser pulse width is 15 picoseconds-1 nanosecond, the laser wavelength is 532-808nm, the laser power is 100-600W, and the spot area is 100μm×100μm-300μm×300μm.

[0039] The embodiment of the present application provides a solar cell, comprising: a cell having a cut surface, and a silicon oxide layer located on the cut surface; The method for preparing the silicon oxide layer comprises: Spray ultrapure water on the cut surface of the cell to form a water film; The water film is scanned by laser to ionize the ultrapure water in the water film, generating hydrogen ions and oxygen ions, and the oxygen ions are used to form a silicon oxide layer on the cutting surface.

[0040] In some embodiments, the thickness of the silicon oxide layer is 3-10 nm. If the silicon oxide layer is too thin, it cannot effectively cover all defects on the cut surface of the cell, resulting in increased carrier recombination, which will affect the passivation effect of the cut surface of the cell; if the silicon oxide layer is too thick, the passivation stability will not improve with the increase of thickness, but will cause material waste and increase production costs. Specifically, the thickness of the silicon oxide layer can be 3 nm, 5 nm, 8 nm, 10 nm. .

[0041] It should be noted that the battery edge passivation method of the embodiment of the present application can be applied not only to the edge passivation of rectangular battery cells, but also to the edge passivation of any irregular polygonal battery cells. For example, a square (or rectangular) battery cell with one or several chamfers does not affect the application of the battery edge passivation method in its shape. It is just that during the manufacturing process, the cut surfaces are first sprayed with a water film and then the water film is scanned with a laser until the cut surfaces that need to be passivated are all passivated.

[0042] The following specific embodiments further describe the present application in detail, but should not be construed as limiting the present application. Without departing from the spirit and substance of the present application, modifications or replacements made to the structure of the present application are within the scope of the present application.

[0043] Example 1 Embodiment 1 provides a solar cell, wherein a method for passivating a cell edge of the solar cell comprises: S100a: Slicing the entire battery using a laser to obtain a plurality of battery cells, each of which has a cutting surface; Sa: Ultrapure water with a conductivity of 1.0uS / cm is sprayed on the cut surface of the cell using an atomizing spray device to form a water film with a thickness of 5mm; the spray pressure is 0.5MPa, the spray flow rate is 5L / min, and the spray time is 5s; S300a: A laser scanner is used to perform laser scanning on the water film to ionize the ultrapure water in the water film, generate hydrogen ions and oxygen ions, and form a silicon oxide layer with a thickness of 7nm on the cut surface to obtain a solar cell; wherein the laser pulse width is 30 picoseconds, the laser wavelength is 532nm, the laser power is 100W, and the spot area is 200μm×200μm.

[0044] Example 2 The solar cell of Example 2 is prepared by referring to the cell edge passivation method of Example 1, except that step S200a and step S300a are different. In Example 2, S200a: Spray ultrapure water with a conductivity of 0.5uS / cm on the cut surface of the battery cell to form a water film with a thickness of 3mm; wherein the spray pressure is 0.5MPa, the spray flow rate is 3L / min, and the spray time is 10s; S300a: A laser scanner is used to perform laser scanning on the water film to ionize the ultrapure water in the water film, generate hydrogen ions and oxygen ions, and form a silicon oxide layer with a thickness of 3nm on the cut surface to obtain a solar cell; wherein the laser pulse width is 15 picoseconds, the laser wavelength is 650nm, the laser power is 500W, and the spot area is 500μm×500μm.

[0045] Example 3 The solar cell of Example 3 is prepared by referring to the cell edge passivation method of Example 1, except that step S200a and step S300a are different. In Example 3, S200a: Spray ultrapure water with a conductivity of 1.2uS / cm on the cut surface of the battery cell to form a water film with a thickness of 1mm; wherein the spray pressure is 0.3MPa, the spray flow rate is 1L / min, and the spray time is 8s; S300a: A laser scanner is used to perform laser scanning on the water film to ionize the ultrapure water in the water film, generate hydrogen ions and oxygen ions, and form a silicon oxide layer with a thickness of 5nm on the cut surface to obtain a solar cell; wherein the laser pulse width is 70 picoseconds, the laser wavelength is 532nm, the laser power is 1000W, and the spot area is 300μm×300μm.

[0046] Example 4 The solar cell of Example 4 is prepared by referring to the cell edge passivation method of Example 1, except that step S200a and step S300a are different. In Example 4, S200a: Spray ultrapure water with a conductivity of 1.8uS / cm on the cut surface of the battery cell to form a water film with a thickness of 0.5mm; wherein the spray pressure is 0.7MPa, the spray flow rate is 8L / min, and the spray time is 3s; S300a: A laser scanner is used to perform laser scanning on the water film to ionize the ultrapure water in the water film, generate hydrogen ions and oxygen ions, and form a silicon oxide layer with a thickness of 8nm on the cut surface to obtain a solar cell; wherein the laser pulse width is 100 picoseconds, the laser wavelength is 905nm, the laser power is 300W, and the spot area is 50μm×50μm.

[0047] In order to more clearly illustrate the technical effects of the embodiments of the present application, the present application uses a cell without edge passivation as comparative example 1 (i.e., the solar cell of comparative example 1). The present application prepares the solar cells of embodiments 1 to 4 and comparative example 1 into corresponding photovoltaic modules, and tests the cell efficiency Eff, open circuit voltage Voc, short circuit current Isc, and fill factor FF of the corresponding photovoltaic modules, and the test results are shown in Table 1.

[0048] Table 1

[0049] It can be seen from the data in Table 1 that, compared with the solar cell of Comparative Example 1, the short-circuit current of the photovoltaic modules of Examples 1 to 4 of the present application is slightly improved, and the cell efficiency and fill factor are significantly improved.

[0050] In summary, in the embodiment of the present application, ultrapure water (DI) is first sprayed on the cut surface of the battery cell to form a water film, and then the water film is scanned by laser to ionize the ultrapure water in the water film to generate hydrogen ions (H + ) and oxygen ions (O 2- ), hydrogen ions can repair the silicon dangling bonds on the surface of the cut surface, and oxygen ions can react with the silicon on the cut surface to form a silicon oxide layer (i.e., a passivation layer), thereby reducing the recombination center of the cut surface of the cell, ensuring the quality and performance of the edge of the cell, and improving the conversion efficiency of the solar cell. In addition, the passivation method does not require ultraviolet light irradiation equipment, heat treatment equipment, and coating equipment, etc. The equipment investment cost is low, the process is simple, the processing rhythm is fast, and it is conducive to industrial production.

[0051] It should be noted that the terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The orientation words "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Therefore, the exemplary term "above..." can include both "above..." and "below..." orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here are interpreted accordingly.

[0052] It should be noted that the terms "first", "second", "front", "back", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0053] It should also be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0054] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0055] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A battery edge passivation method, characterized in that: include: Slicing the whole battery to obtain a battery cell, wherein the battery cell has a cutting surface; Spraying ultrapure water on the cut surface of the battery cell to form a water film; The water film is subjected to laser scanning to ionize the ultrapure water in the water film to generate hydrogen ions and oxygen ions, and the oxygen ions are used to form a silicon oxide layer on the cutting surface.

2. The battery edge passivation method according to claim 1, characterized in that: The conductivity of the ultrapure water is less than 2uS / cm.

3. The battery edge passivation method according to claim 1, characterized in that: During the process of spraying the ultrapure water, the spraying pressure is 0.3-0.7 MPa, the spraying flow rate is 0.1-10 L / min, and the spraying time is 1-10 s.

4. The battery edge passivation method according to claim 1, characterized in that: The thickness of the water film is 0.1 mm-5 mm.

5. The battery edge passivation method according to claim 1, characterized in that: Spraying ultrapure water on the cut surface of the battery cell, comprising: using an atomizing spray device to spray the ultrapure water on the cut surface of the battery cell; Wherein, the distance between the nozzle of the atomizing spray device and the cutting surface is 10-50 mm.

6. The battery edge passivation method according to any one of claims 1 to 5, characterized in that: When performing the laser scanning, the laser pulse width is greater than or equal to 15 picoseconds; and / or When performing the laser scanning, the laser wavelength is 355nm-1064nm.

7. The battery edge passivation method according to any one of claims 1 to 5, characterized in that: When performing the laser scanning, the laser power is 50W-1000W; and / or When performing the laser scanning, the spot area is 50 μm×50 μm-500 μm×500 μm.

8. The battery edge passivation method according to any one of claims 1 to 5, characterized in that: When performing the laser scanning, the laser pulse width is 15 picoseconds-1 nanosecond, the laser wavelength is 532-808nm, the laser power is 100-600W, and the spot area is 100μm×100μm-300μm×300μm.

9. A solar cell, characterized in that: include: A cell having a cutting surface, and a silicon oxide layer located on the cutting surface; Wherein, the preparation method of the silicon oxide layer comprises: Spraying ultrapure water on the cut surface of the battery cell to form a water film; The water film is subjected to laser scanning to ionize the ultrapure water in the water film to generate hydrogen ions and oxygen ions, and the silicon oxide layer is formed on the cutting surface using the oxygen ions.

10. The solar cell according to claim 9, characterized in that: The thickness of the silicon oxide layer is 3-10 nm.

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