Battery piece and manufacturing method thereof

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a battery piece and a manufacturing method thereof. The battery piece comprises a substrate which comprises a front surface and a back surface which are opposite to each other; the front electrode is positioned on the front surface; the at least one doping structure is positioned on the back surface, and the doping structure contains a first type of doping ions; the tunneling layer at least covers the back surface and the surface, away from the substrate, of the doping structure; the doped conductive layer covers the surface of the tunneling layer, and the doped conductive layer contains a second type of doped ions; the back surface electrode is positioned on the back surface and is electrically connected with the doped conductive layer; wherein the first type of doped ions is one of N-type doped ions or P-type doped ions, and the second type of doped ions is the other one of N-type doped ions or P-type doped ions.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is a divisional application of the Chinese invention patent application with the application date of March 4, 2025, application number 202510252259.3, and invention name “Battery Cell and Its Manufacturing Method”. Technical Field

[0003] The embodiments of the present disclosure relate to the photovoltaic field, and in particular to a solar cell and a method for manufacturing the same. Background Art

[0004] Photovoltaic power generation refers to the conversion of solar energy into electrical energy through the photovoltaic effect of semiconductors. For example, TOPCON (Tunnel Oxide Passivated Contact) cells have attracted increasing attention due to their excellent photoelectric conversion performance.

[0005] TOPCON cells are a type of solar cell technology based on the principle of selective carrier transport using a tunneling oxide passivation contact. In TOPCON solar cells, selective carrier transport is achieved by forming a passivation contact structure on the substrate surface. The passivation contact structure consists of a tunneling layer and a doped conductive layer. Summary of the Invention

[0006] The embodiments of the present disclosure provide a battery cell and a method for manufacturing the same, which can at least improve the hot spot effect of the battery cell.

[0007] According to some embodiments of the present disclosure, on one hand, the embodiments of the present disclosure provide a battery cell, comprising: a substrate, the substrate comprising a front side and a back side relative to each other; a front electrode, the front electrode being located at the front side; at least one doping structure, the doping structure being located at the back side, and the doping structure containing a first type of doping ion; a tunneling layer, the tunneling layer at least covering the back side and the surface of the doping structure away from the substrate; a doped conductive layer, the doped conductive layer covering the surface of the tunneling layer, and the doped conductive layer containing a second type of doping ion; a back electrode, the back electrode being located at the back side and electrically connected to the doped conductive layer; wherein the first type of doping ion is one of N-type doping ion or P-type doping ion, and the second type of doping ion is the other of N-type doping ion or P-type doping ion.

[0008] In some embodiments, the substrate includes a doped region, the doped region being in contact with and facing the doped structure.

[0009] In some embodiments, the substrate includes an edge region and a central region located in the edge region, and a junction depth of the doped region located in the edge region is smaller than a junction depth of the doped region located in the central region.

[0010] In some embodiments, the doped conductive layer covers at least a portion of a sidewall of the doped structure.

[0011] In some embodiments, the doping structure includes multiple rows of doping structure groups, each row of the doping structure group includes multiple sub-doping structures, and the sub-doping structures in two adjacent rows of the doping structure groups are staggered.

[0012] According to some embodiments of the present disclosure, on the other hand, the embodiments of the present disclosure further provide a method for manufacturing a battery cell, including: providing a substrate, the substrate including a relative front and back surface; forming at least one doping structure, the doping structure being located on the back surface, and the doping structure containing a first type of doping ion; forming a tunneling layer, the tunneling layer at least covering the back surface and the surface of the doping structure away from the substrate; forming a doped conductive layer, the doped conductive layer covering the surface of the tunneling layer, and the doped conductive layer containing a second type of doping ion; forming a front electrode and a back electrode, the front electrode being located on the front surface, the back electrode being located on the back surface, and being electrically connected to the doped conductive layer; wherein the first type of doping ion is one of an N-type doping ion or a P-type doping ion, and the second type of doping ion is the other of an N-type doping ion or a P-type doping ion.

[0013] In some embodiments, the method for forming the doping structure includes: forming an initial doping structure, wherein the initial doping structure covers the entire back side of the substrate; performing laser processing, converting a portion of the initial doping structure into the doping structure through the laser processing, and forming a doping region in the substrate; removing the initial doping structure that has not been processed by the laser, and the remaining initial doping structure constitutes the doping structure.

[0014] In some embodiments, the method for forming the doping structure includes: doping a portion of the substrate to convert a portion of the substrate into an initial doping structure; performing laser processing to increase the doping depth of the initial doping structure at a corresponding position of the doping region through the laser processing; etching the initial doping structure to remove the initial doping structure that has not been processed by the laser, and the remaining initial doping structure constitutes the doping structure.

[0015] In some embodiments, after the laser treatment, the method further includes: performing a heating treatment to increase the junction depth at a corresponding position of the doping structure.

[0016] In some embodiments, the heating treatment includes: a first heating step, wherein the first heating step is used to heat the temperature of the heating treatment to a first preset temperature; and a second heating step, wherein the second heating step is used to heat the temperature of the heating treatment to a second preset temperature; wherein the heating rate of the first heating step is greater than the heating rate of the second heating step.

[0017] The technical solution provided by the embodiments of the present disclosure has at least the following advantages: wherein, the substrate, the front electrode, the tunneling layer, the doped conductive layer and the back electrode constitute a TOPCON battery, and a doped conductive layer is formed on the back of the TOPCON battery, and the doped ion type in the doped conductive layer is different from the doped ion type in the doped structure, and the doped conductive layer and the doped structure are directly contacted to form a composite contact, or the composite contact is achieved through a dielectric layer to form a leakage structure on the back of the battery cell, and the leakage structure is used to reduce the voltage on the opposite sides of the battery cell, thereby reducing the heat power of the battery cell, so as to improve the hot spot phenomenon caused by poor local conductivity of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the traditional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A cross-sectional view of a battery cell provided in one embodiment of the present disclosure;

[0020] Figure 2 A top view of a battery cell provided in one embodiment of the present disclosure;

[0021] Figures 3 to 5 This is a schematic structural diagram corresponding to each step of a method for manufacturing a battery cell provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0022] As can be seen from the background technology, some TOPCON batteries currently have working conditions that are different from other battery cells due to local obstruction, damage or inconsistent performance, which in turn causes overheating, which can seriously burn the battery cells and cause them to fail.

[0023] An embodiment of the present disclosure provides a battery cell, which is composed of a TOPCON battery through a substrate, a front electrode, a tunneling layer, a doped conductive layer and a back electrode. A doped conductive layer is formed on the back of the TOPCON battery, and the type of doped ions in the doped conductive layer is different from the type of doped ions in the doped structure. The doped conductive layer and the doped structure are in direct contact to form a composite contact, or the composite contact is achieved through a dielectric layer to form a leakage structure on the back of the battery cell. The leakage structure is used to reduce the voltage on the opposite sides of the battery cell, thereby reducing the heat power of the battery cell, so as to improve the hot spot phenomenon caused by poor local conductivity of the battery cell.

[0024] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are used solely to distinguish between different objects and should not be understood to indicate or imply relative importance or to implicitly specify the quantity, specific order, or primary and secondary relationship of the technical features indicated. In the description of the embodiments of the present disclosure, "plurality" means more than two, unless otherwise specifically defined.

[0025] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present disclosure. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0026] In the description of the embodiments of the present disclosure, the term "and / or" is merely a description of an association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B can represent the following three situations: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0027] In the description of the embodiments of the present disclosure, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0028] In the description of the embodiments of the present disclosure, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present disclosure 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 operate in a specific orientation, and therefore should not be understood as limiting the embodiments of the present disclosure.

[0029] In the description of the embodiments of the present disclosure, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and they can refer to internal connectivity between two components or interaction between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present disclosure based on specific circumstances.

[0030] In the accompanying drawings corresponding to the embodiments of the present disclosure, the thickness and area of ​​the layers are exaggerated for better understanding and ease of description. When describing a component (such as a layer, film, region or substrate) on another component or on the surface of another component, the component can be "directly" located on the surface of the other component, or a third component can be present between the two components. Conversely, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component as being "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a partial edge of the entire surface.

[0031] In the description of the embodiments of the present disclosure, when a component is referred to as "including" another component, unless otherwise specified, other components are not excluded, and other components may be further included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on / located on" another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component can be present between them. In addition, when a component such as a layer, film, region, or plate is "directly on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it means that no other components are located between them.

[0032] The terms used herein in the description of the various embodiments are intended only to describe the specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is intended to include the plural form unless the context clearly indicates otherwise. A component includes a layer, film, region, or plate.

[0033] The following describes various embodiments of the present disclosure in detail with reference to the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in the various embodiments of the present disclosure to facilitate a better understanding of the present disclosure. However, even without these technical details and the various variations and modifications based on the following embodiments, the technical solutions claimed in the present disclosure can still be implemented.

[0034] refer to Figure 1 and Figure 2 , Figure 1 A cross-sectional view of a battery cell provided in accordance with an embodiment of the present disclosure; Figure 2 A top view of the doping structure on the substrate surface.

[0035] In some embodiments, the battery cell may include a substrate 100 , wherein the substrate 100 includes a front surface 110 and a back surface 120 opposite to each other.

[0036] The battery cell may further include a front electrode 101 , which is located on the front side 110 .

[0037] The cell may further include: at least one doping structure 102 , the doping structure 102 being located on the back surface 120 , and containing first type doping ions.

[0038] The cell may further include a tunneling layer 103 , where the tunneling layer 103 at least covers the back surface 120 and the surface of the doping structure 102 away from the substrate 100 .

[0039] The cell may further include: a doped conductive layer 104 , the doped conductive layer 104 covers the surface of the tunneling layer 103 , and the doped conductive layer 104 contains second type dopant ions.

[0040] The battery cell may further include: a back electrode 105, which is located on the back side 120 and electrically connected to the doped conductive layer 104, wherein the first type of dopant ions are one of N-type dopant ions or P-type dopant ions, and the second type of dopant ions are the other of N-type dopant ions or P-type dopant ions.

[0041] An embodiment of the present disclosure provides a cell, which comprises a TOPCON cell formed by a substrate 100, a front electrode 101, a tunneling layer 103, a doped conductive layer 104 and a back electrode 105. A doped conductive layer 104 is formed on the back side 120 of the TOPCON cell, and the doped ion type in the doped conductive layer 104 is different from the doped ion type in the doped structure 102. A composite contact is formed by direct contact between the doped conductive layer and the doped structure, or a composite contact is achieved through a dielectric layer, so as to form a leakage structure on the back side of the cell. The leakage structure is used to reduce the voltage on opposite sides of the cell, thereby reducing the heat generation power of the cell, and improving the hot spot phenomenon caused by poor local conductivity of the cell.

[0042] The substrate 100 has a front side 110 and a back side 120 relative to each other. In some embodiments, the battery cell is a single-sided battery cell, and the front side 110 of the substrate 100 can be used as a light-receiving surface for receiving incident light, and the back side 120 can be used as a backlight surface. In some embodiments, the battery cell is a double-sided battery cell, and both the front side 110 and the back side 120 of the substrate 100 can be used as light-receiving surfaces, and can be used to receive incident light. It can be understood that the backlight surface referred to in the embodiments of the present disclosure can also receive incident light, but the degree of reception of the incident light is weaker than that of the light-receiving surface, and therefore it is defined as a backlight surface.

[0043] In some embodiments, a texturing process can be performed on at least one of the front surface 110 or the back surface 120 of the substrate 100 to form a velvet surface on at least one of the front surface 110 or the back surface 120 of the substrate 100. This can enhance the absorption and utilization efficiency of incident light by the front surface 110 and the back surface 120 of the substrate 100. In some embodiments, the velvet surface can be a pyramid velvet surface. As a common velvet surface, the pyramid velvet surface not only reduces the reflectivity of the surface of the substrate 100 but also forms light traps, enhancing the substrate 100's absorption of incident light and improving the photovoltaic conversion efficiency of the solar cell.

[0044] In some embodiments, the substrate 100 includes a doping region 106, which is in contact with and directly opposite to the doping structure 102. On the one hand, the doping region 106 can also constitute a part of the leakage structure of the cell, thereby further improving the hot spot phenomenon of the cell; on the other hand, the provision of the doping region 106 can also facilitate the formation of the leakage structure on the back side 120 of the cell. For the doping structure 102, it must be formed on the entire back side 120 of the substrate 100 during formation. Then, by removing part of the doping structure 102 to form a partial coverage effect on the back side 120, when forming the doping region 106, part of the doping structure 102 can be removed, thereby avoiding the problem of the entire doping structure 102 being removed, which would cause the leakage structure to fail, thereby improving the process tolerance.

[0045] In some embodiments, the junction depth of the doped region 106 is 500nm to 2μm, for example, 700nm, 900nm, 1.3μm, 1.5μm, or 1.8μm, etc. For the doped region 106, the deeper the junction depth of the doped region 106, the stronger the leakage effect of the doped region 106. Similarly, if the junction depth of the doped region 106 is too deep, it will affect the light absorption ability of the cell substrate and cause a large number of carriers to recombine at the corresponding position of the doped region 106, affecting the photoelectric conversion efficiency of the cell. Therefore, by setting the junction depth of the doped region 106 to 500nm to 2μm, it is possible to improve the hot spot effect of the cell while avoiding affecting the efficiency of the cell.

[0046] In some embodiments, the substrate 100 includes an edge region and a central region within the edge region, and the junction depth of the doped region 106 in the edge region is less than the junction depth of the doped region 106 in the central region. The edge region of the substrate 100 is the location corresponding to the edge of the substrate 100, while the central region of the substrate 100 is the portion located at the center of the substrate 100. Taking a square as an example, the edge region is the portion adjacent to the edge of the square, and the central region is the portion surrounded by the edge region. Since the edge region of the substrate 100 is close to the edge of the cell, an effect similar to tip discharge will occur. Therefore, the leakage effect in the edge region can be weakened by reducing the junction depth of the doped layer in the edge region, thereby making the leakage effect in the edge region and the central region relatively uniform, thereby improving the performance of the cell.

[0047] In some embodiments, the orthographic projection of the doping structure 102 on the surface of the substrate 100 is a circle or a polygon. The polygon can be a regular shape such as a rectangle or a square. For the doping structure 102, setting the orthographic projection of the doping structure 102 on the surface of the substrate 100 to be a circle or a polygon can reduce the difficulty of forming the doping structure 102. In particular, when the orthographic projection of the doping structure 102 on the surface of the substrate 100 is a circle, the circular doping structure 102 has the highest leakage efficiency compared to the polygonal doping structure 102. While achieving the same leakage effect, the circular doping structure 102 produces the least recombination with the doped conductive layer 104.

[0048] In some embodiments, the thickness of the doping structure 102 is 0.01 to 1 μm, for example, 0.05 μm, 0.2 μm, 0.5 μm, 0.8 μm, or 0.95 μm. As for the doping structure 102, the thicker the doping structure 102, the better the leakage effect brought by the doping structure 102. Similarly, the thicker the doping structure 102, the more recombination occurs between the doping structure 102 and the doped conductive layer 104. Therefore, by setting the thickness of the doping structure 102 to 0.01 to 1 μm, the leakage effect of the doping structure 102 can be improved while avoiding affecting the efficiency of the solar cell.

[0049] In some embodiments, the size of the doping structure 102 is 1 to 100 μm. The size here can refer to the diameter of a circle, the side length of a square, the long side of a rectangle, or the distance between the two most distant points of the orthographic projection of the doping structure 102 on the surface of the substrate 100. Setting the size of the doping structure 102 to 1 to 100 μm can also improve the leakage effect of the doping structure 102 while avoiding affecting the efficiency of the solar cell.

[0050] It is understandable that the larger the size of the doping structure 102, the better the leakage effect brought by the doping structure. Similarly, the larger the size of the doping structure 102, the more carriers will recombine at the corresponding position of the doping structure 102, which will affect the collection and transmission of carriers in the battery cell.

[0051] In some embodiments, the ratio of the area of ​​the orthogonal projection of the doping structure 102 on the back surface 120 to the area of ​​the back surface 120 is 0.00001% to 0.01%. Similarly, the larger the ratio of the area of ​​the orthogonal projection of the doping structure 102 on the back surface 120 to the area of ​​the back surface 120, the better the leakage effect brought by the doping structure 102. The smaller the ratio of the area of ​​the orthogonal projection of the doping structure 102 on the back surface 120 to the area of ​​the back surface 120, the lower the ability of the doping structure 102 to affect the efficiency of the solar cell. By setting the ratio of the area of ​​the orthogonal projection of the doping structure 102 on the back surface 120 to the area of ​​the back surface 120 to 0.00001% to 0.01%, the leakage effect of the doping structure 102 can be improved while avoiding affecting the photoelectric conversion efficiency of the solar cell.

[0052] In some embodiments, the doping structures 102 are arranged in an array. Arranging the doping structures 102 in an array allows the doping structures 102 to be evenly distributed on the back surface 120 of the cell, thereby ensuring that corresponding leakage structures exist at all locations on the cell to improve hot spot issues.

[0053] In some embodiments, the doping structure 102 includes multiple rows of doping structure groups 112, each row of the doping structure group 112 includes multiple sub-doping structures 122, and the sub-doping structures 122 in two adjacent rows of the doping structure group 112 are staggered. In other words, the doping structure 102 is composed of multiple sub-doping structures 122. By staggering the sub-doping structures 122 in two adjacent rows, the uniformity of the leakage structure arrangement on the back side 120 of the cell can be further improved, thereby further improving the coverage of the doping structure 102 in improving the hot spot phenomenon.

[0054] It can be understood that, for the doping structure 102, the ability of a doping structure 102 to improve the hot spot phenomenon is within a range. For example, taking the circular doping structure 102 as an example, the leakage of the doping structure 102 can improve the hot spot phenomenon in a certain area. When the location where the hot spot phenomenon occurs is a certain distance away from the doping structure 102, the doping structure 102 cannot affect it. Therefore, by setting the sub-doping structures 122 in the doping structure groups 112 of two adjacent rows in the doping structure 102 to be staggered with each other, the range that the doping structure 102 can affect can be increased, and the reliability of the battery cell can be further improved.

[0055] In some embodiments, the doped structure 102 includes: a silicon substrate layer containing the first type of dopant ions, a silicon compound containing the first type of dopant ions, or a silicon oxide containing the first type of dopant ions. In other words, the doped structure 102 can be formed by converting a portion of the substrate 100 into the doped structure 102, or by forming an additional layer of the doped structure 102 on the surface of the substrate 100. Different materials and formation methods can be selected based on different process requirements.

[0056] In some embodiments, the doped conductive layer 104 covers at least a portion of the sidewalls of the doped structure 102. In other words, the doped conductive layer 104 can directly contact the doped structure 102, and a leakage structure can be formed through direct contact. By providing the doped conductive layer 104 to cover at least a portion of the sidewalls of the doped structure 102, the leakage capability of the doped structure 102 can be further improved, and the hot spot effect of the cell can be further improved.

[0057] In some embodiments, tunneling layer 103 covers the surface of doped structure 102, doped conductive layer 104 covers the surface of tunneling layer 103, and tunneling layer 103 is separated from doped structure 102 and doped conductive layer 104. By separating doped conductive layer 104 from doped structure 102, it is possible to prevent doped structure 102 from excessively affecting the photoelectric conversion efficiency of the cell and thus the performance of the cell.

[0058] The doped conductive layer 104 and the tunneling layer 103 constitute the passivation contact structure of the cell. The passivation contact structure provides good surface passivation for the back side 120 of the substrate 100. The tunneling layer 103 allows majority carriers to tunnel into the doped conductive layer 104 while blocking the recombination of minority carriers, so that majority carriers are transmitted laterally in the doped conductive layer 104 and collected by the metal electrode, thereby greatly reducing the metal contact recombination current and improving the open circuit voltage and short circuit current of the solar cell.

[0059] In some embodiments, the battery cell further includes a first passivation layer 107, which covers the surface of the doped conductive layer 104 away from the substrate 100. The first passivation layer 107 can have a good passivation effect on the back side 120 of the substrate 100. For example, it can better chemically passivate the dangling bonds on the back side 120, saturate the dangling bonds on the back side 120, reduce the defect state density on the back side 120, and inhibit carrier recombination on the back side 120.

[0060] In some embodiments, a front doping layer 108 and a second passivation layer 109 are also included. The front doping layer 108 covers the front surface 110 of the substrate 100, and the second passivation layer 109 covers the surface of the front doping layer 108 away from the substrate 100. The front electrode 101 is in contact and electrically connected with the front doping layer 108.

[0061] In some embodiments, the front doped layer 108 and the doped structure 102 have the same doping ion concentration, so that the front doped layer 108 and the doped structure 102 can be formed in the same process step.

[0062] An embodiment of the present disclosure provides a cell, which comprises a TOPCON cell formed by a substrate 100, a front electrode 101, a tunneling layer 103, a doped conductive layer 104 and a back electrode 105. A doped conductive layer 104 is formed on the back side 120 of the TOPCON cell, and the doped ion type in the doped conductive layer 104 is different from the doped ion type in the doped structure 102. A composite contact is formed by direct contact between the doped conductive layer and the doped structure, or a composite contact is achieved through a dielectric layer, so as to form a leakage structure on the back side of the cell. The leakage structure is used to reduce the voltage on opposite sides of the cell, thereby reducing the heat generation power of the cell, and improving the hot spot phenomenon caused by poor local conductivity of the cell.

[0063] Another embodiment of the present disclosure further provides a method for manufacturing a battery cell, which can be used to form battery cells as in some or all of the above-mentioned embodiments. The method for manufacturing a battery cell provided by another embodiment of the present disclosure will be described below in conjunction with the accompanying drawings. It should be noted that the same or corresponding parts of the above-mentioned embodiments can refer to the corresponding description of the above-mentioned embodiments and will not be repeated below.

[0064] refer to Figures 3 to 5 and Figure 1 , Figures 3 to 5 and Figure 1 This is a schematic structural diagram corresponding to each step of a method for manufacturing a battery cell provided by an embodiment of the present disclosure.

[0065] In some embodiments, a method for manufacturing a battery cell may include: providing a substrate 100 , wherein the substrate 100 includes a front surface 110 and a back surface 120 opposite to each other.

[0066] The method for manufacturing the cell may further include: forming at least one doping structure 102 , the doping structure 102 being located on the back surface 120 , and containing first type doping ions.

[0067] The method for manufacturing the cell may further include: forming a tunneling layer 103 , where the tunneling layer 103 at least covers the back surface 120 and the surface of the doping structure 102 away from the substrate 100 .

[0068] The manufacturing method of the battery cell may further include: forming a doped conductive layer 104 , where the doped conductive layer 104 covers the surface of the tunneling layer 103 , and the doped conductive layer 104 contains second type dopant ions.

[0069] The method for manufacturing the battery cell may also include: forming a front electrode 101 and a back electrode 105, the front electrode 101 is located on the front side 110, and the back electrode 105 is located on the back side 120, and is electrically connected to the doped conductive layer 104, wherein the first type of dopant ions are one of N-type dopant ions or P-type dopant ions, and the second type of dopant ions are the other of the N-type dopant ions or P-type dopant ions.

[0070] In the process of forming the TOPCON battery, a doping structure 102 is formed on the back side 120, and the doping structure 102 and the doped conductive layer 104 are used to form a leakage channel. The leakage channel is used to improve the hot spot effect of the battery cell, thereby avoiding damage to the battery cell caused by the hot spot effect, thereby avoiding failure of the battery cell and improving the reliability of the battery cell.

[0071] refer to Figure 3 , Figure 3 The morphology of a substrate provided in an embodiment of the present disclosure.

[0072] In some embodiments, after providing the substrate 100 , the surface of the substrate 100 may be textured to form a pyramid morphology on the front side 110 and / or the back side 120 of the substrate 100 , thereby improving the light absorption capability of the substrate 100 .

[0073] refer to Figure 4 and Figure 5 , Figure 4 For Figure 3 An initial doping structure is formed on the basis of Figure 5 For Figure 4 A doping structure is formed on this basis.

[0074] In some embodiments, the method of forming the doping structure 102 includes: forming an initial doping structure 132, the initial doping structure 132 covering the entire back side 120 of the substrate 100; performing laser processing to convert part of the initial doping structure 132 into the doping structure 102 through laser processing, and forming a doping region 106 in the substrate 100; removing the initial doping structure 132 that has not been laser processed, and the remaining initial doping structure 132 constitutes the doping structure 102.

[0075] The initial doping structure 132 is formed by first depositing the entire surface. The etching selectivity between the laser-treated portion and the non-laser-treated portion changes before and after laser treatment. The difference in etching selectivity is utilized to remove the non-laser-treated initial doping structure 132, completing the formation of the doping structure 102. Compared to directly forming the doping structure 102 in a localized area of ​​the back surface 120, the method of removing the initial doping structure 132 after forming it reduces the process difficulty and makes it easier to control the position of the doping structure 102, thereby allowing the position of the doping structure 102 to be adjusted as needed. Furthermore, by forming the doping region 106 within the substrate 100, the problem of removing the entire initial doping structure 132 during the etching process, which could lead to leakage path failure, can be avoided.

[0076] In some embodiments, the method for forming the doped structure 102 includes: doping a portion of the substrate 100 to convert the portion of the substrate 100 into an initial doped structure 132; performing laser treatment to increase the doping depth of the initial doped structure 132 at a position corresponding to the doping region 106; and etching the initial doped structure 132 to remove the initial doped structure 132 not subjected to the laser treatment, with the remaining initial doped structure 132 constituting the doped structure 102. In other words, a portion of the substrate 100 is converted into the initial doped structure 132, and then laser treatment is performed to increase the junction depth at a position corresponding to the portion of the initial doped structure 132, and then etching is performed to remove at least the portion of the initial doped layer not subjected to the laser treatment to form the doped structure 102.

[0077] The difficulty of manufacturing the cell can also be reduced by converting part of the substrate 100 into the doping structure 102. Moreover, by deepening the junction depth of the initial doping structure 132 at some locations through laser processing, the position of the doping structure 102 can also be easily controlled.

[0078] It can be understood that the junction depth of the corresponding position of the part of the initial doping structure 132 is deepened by laser processing, and the whole surface etching method can be used when etching the initial doping structure 132. Since the junction depth of the laser-processed position is deeper, after the initial doping structure 132 that has not been laser-processed is removed, part of the doping structure 102 that has been laser-processed will still be retained.

[0079] In some embodiments, the initial doping structure 132 may be formed on both the front surface 110 and the back surface 120 of the substrate 100 by single insertion diffusion, and then laser treatment may be performed only on the back surface 120 .

[0080] In some embodiments, after the laser treatment, a heating process is further performed to increase the doping junction depth at locations corresponding to the doping structure 102. Further increasing the junction depth at locations corresponding to the doping structure 102 can, on the one hand, further improve the leakage effect of the doping structure 102, and on the other hand, can also improve the formation tolerance of the solar cell manufacturing method, thereby avoiding the removal of the doping structure 102 that needs to be retained at the same time as the initial doping structure 132, thereby improving the stability of the process.

[0081] In some embodiments, the heating treatment includes: a first heating step, the first heating step is used to heat the temperature of the heating treatment to a first preset temperature; a second heating step, the second heating step is used to heat the temperature of the heating treatment to a second preset temperature; wherein the heating rate of the first heating step is greater than the heating rate of the second heating step.

[0082] The first heating step may be a preheating step, by which the ambient temperature of the cell is rapidly heated to a first preset temperature. The second heating step may be to control the increase in the doping junction depth at the corresponding position of the doping structure 102 while heating the heat treatment to an optimal temperature. For the first heating step, the first heating step is used for the preset, therefore, the heating rate of the first heating step may be controlled to be faster, thereby facilitating the reduction of the process time of the entire manufacturing method. For the second heating step, the second heating step is heating while diffusing, therefore, the heating rate of the second heating step needs to be controlled to provide diffusion time for the ions, thereby achieving two goals at the same time, thereby reducing the time the cell is in the second heating step.

[0083] In some embodiments, the first preset temperature is 800° C. to 900° C., such as 810° C., 820° C., 840° C., 860° C., 880° C., or 890° C., and the second preset temperature is 1000° C. to 1200° C., such as 1050° C., 1080° C., 1100° C., 1130° C., 1160° C., or 1180° C. By using the first temperature increase step to quickly increase the process temperature of the cell to 800° C. to 900° C., it is easy to reach the temperature for subsequent heat treatment. By using the second temperature increase step to increase the process temperature of the cell to 1000° C. to 1200° C., at this temperature, the diffusion of carriers in the cell is facilitated, while increasing the carrier diffusion speed while preventing the carrier diffusion from being too fast.

[0084] In some embodiments, the heating rate of the first heating step is 10-15°C / min, such as 11°C / min, 12°C / min, 13°C / min or 14°C / min, etc., and the heating rate of the second heating step is 3-7°C / min, such as 4°C / min, 5°C / min or 6°C / min, etc. Setting the heating rate of the first heating step to 10-15°C / min can reduce the heating temperature of the heat treatment to the first preset temperature while avoiding the rapid change of the ambient temperature of the battery cell, thereby reducing the possibility of abnormality of the battery cell. Setting the heating rate of the second heating step to 3-7°C / min can enable the battery cell to complete the diffusion of carriers in a gradually heated environment, and avoid the ambient temperature of the battery cell being too fast during the diffusion process, resulting in insufficient uniformity of the carrier diffusion.

[0085] In some embodiments, the heat treatment process duration is 2000s to 10000s. Regarding the heat treatment process duration, the longer the heat treatment process duration, the deeper the doping junction depth at the corresponding position of the initial doping structure 132 will be, and the leakage performance will be stronger. However, excessive doping junction depth will lead to a decrease in the photoelectric conversion efficiency of the formed solar cell. Therefore, by controlling the heat treatment process duration to 2000s to 10000s, the leakage performance of the initial doping structure 132 can be increased while avoiding affecting the photoelectric conversion efficiency of the solar cell.

[0086] Furthermore, the process duration of the heat treatment is 3000 to 7000 seconds. Under this process duration, the leakage performance brought by the initial doping structure 132 and the impact on the photoelectric conversion efficiency of the cell are controlled within a reasonable range.

[0087] In some embodiments, the process parameters of the laser treatment include: a laser type of violet, green, or red light, a laser frequency of 100 to 1000 kHz, a laser spot diameter of 1 to 100 μm, and a laser energy of 1 to 500 W. Under these process parameters, the doping junction depth at the corresponding position of the doping structure 102 can be increased while avoiding excessive damage to the doping structure 102 during the laser treatment, thereby improving the reliability of the resulting solar cell.

[0088] In some embodiments, the process steps for removing the initial doping structure 132 include: a first etching treatment, in which the initial doping structure 132 is etched using hydrofluoric acid with a mass fraction of 30% to 70%; an alkali polishing treatment, in which an alkaline solution is used to clean the initial doping structure 132; and a second etching treatment, in which the initial doping structure 132 is etched using hydrofluoric acid with a mass fraction of 0.5 to 5%.

[0089] The first etching treatment is used to perform large-area cleaning of the initial doping structure 132, thereby completing the purpose of removing the initial doping structure 132. The alkali polishing treatment is used to clean the etching reagent remaining in the first etching treatment on the one hand, and on the other hand, it can also be used to form a velvet surface on the surface of the substrate 100 exposed after etching the initial doping structure 132. The second etching treatment can be used to clean the reagent remaining in the alkali polishing treatment, thereby completing the process step of removing the initial doping structure 132.

[0090] In some embodiments, the alkali polishing treatment may be composed of potassium hydroxide, hydrogen peroxide, an alkali polishing additive, and deionized water.

[0091] In some embodiments, after the first etching treatment, it can also include: a first tank water wash, a tank pre-wash and a second tank water wash, and then an alkali polishing treatment. After the alkali polishing treatment, it can also include: a third tank water wash, a tank post-wash and a second etching treatment after water washing. After the second etching treatment, it can also include a fourth tank water wash, and then drying to complete the purpose of removing the initial doping structure 132.

[0092] It is understandable that the purpose of the tank water washing, tank pre-cleaning, tank post-cleaning and water washing is to remove substances generated by the reaction and remove carriers remaining on the surface of the substrate 100, thereby improving the reliability of the formed battery cell.

[0093] refer to Figure 1 , Figure 1 For Figure 5 A tunneling layer, a doped conductive layer, a first passivation layer and a second passivation layer are formed on the basis of the above-mentioned structure.

[0094] In some embodiments, the tunneling layer 103 and the doped conductive layer 104 can be formed in a back-to-back manner. It should be noted that the back-to-back manner means that the surfaces of the two battery cells are closely attached. Taking the formation of the tunneling layer 103 as an example, the front sides 110 of the two battery cells are relatively close to each other, so that the back sides 120 of the two battery cells face outward. At this time, the tunneling layer 103 is formed on the exposed surfaces of the two battery cells. It can be understood that since the front sides 110 of the two battery cells are not exposed, the tunneling layer 103 will not be formed on the front sides 110 of the battery cells.

[0095] After forming the tunneling layer 103 and the doped conductive layer 104, the wrap-around plating layer located on the front side 110 and the wrap-around plating layer located on the side wall can also be etched away. It can be understood that when the doped conductive layer 104 is formed, a wrap-around plating layer will inevitably be formed on the front side 110 and on the side wall of the substrate 100. At this time, the wrap-around plating layer on the front side 110 and the wrap-around plating layer located on the side wall are removed by etching, so as to avoid affecting the performance of the battery cell.

[0096] It is understandable that, in the process of forming the initial doping layer, since the initial doping layer is also formed on the front surface 110 , the initial doping layer located on the front surface 110 can serve as the front doping layer 108 .

[0097] In some embodiments, the first passivation layer 107 and the second passivation layer 109 are formed on the front surface 110 and the back surface 120. After the first passivation layer 107 and the second passivation layer 109 are formed on the front surface 110 and the back surface 120, the front electrode 101 and the back electrode 105 are formed.

[0098] Those skilled in the art will appreciate that the above-described embodiments are specific examples for implementing the present disclosure, and in actual applications, various changes may be made to them in form and detail without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, the scope of protection of the embodiments of the present disclosure shall be based on the scope defined in the claims.

Claims

1. A battery cell, characterized in that: include: a substrate comprising a front surface and a back surface opposite to each other; a front electrode, the front electrode being located on the front side; at least one doping structure, the doping structure being located on the back surface and containing first type doping ions; a tunneling layer, the tunneling layer covering at least the back surface and a surface of the doping structure away from the substrate; a doped conductive layer, the doped conductive layer covering a surface of the tunneling layer, the doped conductive layer containing second type dopant ions; a back electrode, the back electrode being located on the back surface and electrically connected to the doped conductive layer; The first type dopant ions are either N-type dopant ions or P-type dopant ions, and the second type dopant ions are either N-type dopant ions or P-type dopant ions. The substrate includes: a doped region, which is in contact with and opposite to the doped structure; the substrate includes an edge region and a central region located in the edge region, and the junction depth of the doped region located in the edge region is smaller than the junction depth of the doped region located in the central region.

2. The battery cell according to claim 1, wherein: The doped conductive layer at least covers a portion of the sidewall of the doped structure.

3. The battery cell according to claim 1, wherein: The doping structure includes multiple rows of doping structure groups, each row of the doping structure group includes multiple sub-doping structures, and the sub-doping structures in two adjacent rows of the doping structure groups are staggered with each other.

4. The battery cell according to claim 1, wherein: The doping structures are arranged in an array.

5. The battery cell according to claim 1, characterized in that: The ratio of the area of ​​the orthographic projection of the doping structure on the back surface to the area of ​​the back surface is 0.00001% to 0.01%.

6. A method for manufacturing a battery cell, characterized in that: include: Providing a substrate, the substrate comprising opposite front and back surfaces; forming at least one doping structure, wherein the doping structure is located on the back surface and contains first type doping ions; forming a tunneling layer, wherein the tunneling layer covers at least the back surface and a surface of the doped structure away from the substrate; forming a doped conductive layer, wherein the doped conductive layer covers a surface of the tunneling layer and contains second type dopant ions; forming a front electrode and a back electrode, wherein the front electrode is located on the front surface, and the back electrode is located on the back surface and is electrically connected to the doped conductive layer; The first type dopant ions are either N-type dopant ions or P-type dopant ions, and the second type dopant ions are either N-type dopant ions or P-type dopant ions. The substrate includes: a doped region, which is in contact with and opposite to the doped structure; the substrate includes an edge region and a central region located in the edge region, and the junction depth of the doped region located in the edge region is smaller than the junction depth of the doped region located in the central region.

7. The method for manufacturing a battery cell according to claim 6, wherein: The method for forming the doping structure includes: forming an initial doping structure, wherein the initial doping structure covers the entire back surface of the substrate; performing laser processing to convert a portion of the initial doped structure into the doped structure and form a doped region in the substrate; The initial doping structure that has not been processed by the laser is removed, and the remaining initial doping structure constitutes the doping structure.

8. The method for manufacturing a battery cell according to claim 6, wherein: The method of forming the doped structure includes: doping a portion of the substrate to convert the portion of the substrate into an initial doped structure; Performing laser processing to increase the doping depth of the initial doping structure at a position corresponding to the doping region through the laser processing; etching the initial doping structure to remove the initial doping structure not processed by the laser, and the remaining initial doping structure constitutes the doping structure.

9. The method for manufacturing a battery cell according to claim 7 or 8, characterized in that: After the laser treatment, the method further comprises: A heating process is used to increase the doping junction depth at the corresponding position of the doping structure.

10. The method for manufacturing a battery cell according to claim 9, wherein: Heat treatment includes: a first temperature-raising step, wherein the first temperature-raising step is used to raise the temperature of the heat treatment to a first preset temperature; a second temperature raising step, wherein the second temperature raising step is used to raise the temperature of the heat treatment to a second preset temperature; Wherein, the heating rate of the first heating step is greater than the heating rate of the second heating step.

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