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

Technical Field

[0001] The present disclosure relates to the photovoltaic field, and in particular to a solar cell and a manufacturing method thereof. Background Art

[0002] 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 good photoelectric conversion performance.

[0003] TOPCON cells are a type of tunnel oxide passivation contact solar cell technology based on the principle of selective carriers. In TOPCON solar cells, selective carrier transmission is achieved by forming a passivation contact structure on the substrate surface. The passivation contact structure includes a tunneling layer and a doped conductive layer. Summary of the invention

[0004] 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.

[0005] According to some embodiments of the present disclosure, on one hand, an embodiment of the present disclosure provides a battery cell, comprising: a substrate, the substrate comprising a relative front side and a back side; 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 doped ions; a tunneling layer, the tunneling layer at least covering the back side and a 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 doped ions; 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 doped ions are one of N-type doped ions or P-type doped ions, and the second type of doped ions are the other of N-type doped ions or P-type doped ions.

[0006] In some embodiments, the substrate includes: a doped region, the doped region is in contact with and faces the doped structure.

[0007] 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.

[0008] In some embodiments, the doped conductive layer at least covers a portion of a sidewall of the doped structure.

[0009] 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 with each other.

[0010] 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, comprising: providing a substrate, the substrate comprising a relative front side and a back side; forming at least one doping structure, the doping structure being located at the back side and containing a first type of doping ions; forming a tunneling layer, the tunneling layer at least covering the back side 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, the doped conductive layer containing a second type of doping ions; forming a front electrode and a back electrode, the front electrode being located at the front side, the back electrode being located at the back side, and being electrically connected to the doped conductive layer; wherein the first type of doping ions are one of N-type doping ions or P-type doping ions, and the second type of doping ions are the other of the N-type doping ions or the P-type doping ions.

[0011] 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 to convert a portion of the initial doping structure into the doping structure through the laser processing and form 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.

[0012] In some embodiments, the method for forming the doping structure includes: doping a portion of the substrate to convert the portion of the substrate into an initial doping 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 that has not been processed by the laser, and the remaining initial doping structure constitutes the doping structure.

[0013] 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.

[0014] 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.

[0015] 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 in 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, and the leakage structure is used to reduce the voltage on the opposite sides of the battery cell, thereby reducing the heat generation 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

[0016] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings, and these exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise specified, 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 are 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 creative work.

[0017] Figure 1 A cross-sectional view of a battery cell provided in one embodiment of the present disclosure; Figure 2 A top view of a battery cell provided in one embodiment of the present disclosure; Figures 3 to 5 A schematic structural diagram corresponding to each step of a method for manufacturing a battery cell provided in one embodiment of the present disclosure. DETAILED DESCRIPTION

[0018] As can be seen from the background technology, currently some TOPCON batteries may have partial shielding, damage or inconsistent performance, which may cause their working state to be different from other battery cells, thereby causing overheating, which may seriously burn the battery cells and cause the battery cells to fail.

[0019] The disclosed embodiment 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, 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 in 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, and the leakage structure is used to reduce the voltage on the opposite sides of the battery cell, thereby reducing the heat generation power of the battery cell, so as to improve the hot spot phenomenon caused by poor local conductivity of the battery cell.

[0020] In the description of the embodiments of the present disclosure, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0021] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present disclosure. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0022] In the description of the embodiments of the present disclosure, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0023] 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).

[0024] In the description of the embodiments of the present disclosure, the orientations or positional relationships indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present disclosure and simplifying the description. They do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present disclosure.

[0025] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to the specific circumstances.

[0026] 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 may be "directly" located on the surface of the other component, or a third component may exist between the two components. On the contrary, 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.

[0027] In the description of the embodiments of the present disclosure, when a component "includes" 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 may 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 may exist in between. In addition, when a component such as a layer, film, region, or plate is "directly located 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 in between.

[0028] The terms used in the description of the various embodiments described herein are only used to describe specific embodiments and are not intended to be limiting. As used in the description of the various embodiments described and in the appended claims, "the components" are also intended to include plural forms unless the context clearly indicates otherwise. Among them, components include components such as layers, films, regions, or plates.

[0029] The following will describe the various embodiments of the present disclosure in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present disclosure, many technical details are provided in order to enable the reader to better understand the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present disclosure can be implemented.

[0030] refer to Figure 1 and Figure 2 , Figure 1 A cross-sectional view of a battery cell provided in one embodiment of the present disclosure; Figure 2 A top view of the doping structure on the substrate surface.

[0031] In some embodiments, the battery cell may include a substrate 100 , wherein the substrate 100 includes a front side 110 and a back side 120 opposite to each other.

[0032] The battery cell may further include: a front electrode 101 , and the front electrode 101 is located on the front side 110 .

[0033] The cell may further include: at least one doping structure 102 , the doping structure 102 being located on the back side 120 , and containing first type doping ions.

[0034] The cell may further include: a tunneling layer 103 , wherein the tunneling layer 103 at least covers the back surface 120 and the surface of the doping structure 102 away from the substrate 100 .

[0035] 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 doping ions.

[0036] 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 doped ions are one of N-type doped ions or P-type doped ions, and the second type of doped ions are the other of the N-type doped ions or P-type doped ions.

[0037] The embodiment of the present disclosure provides a battery cell, which is composed of a substrate 100, a front electrode 101, a tunneling layer 103, a doped conductive layer 104 and a back electrode 105 to form a TOPCON battery, and a doped conductive layer 104 is formed on the back side 120 of the TOPCON battery, and the doped ion type in the doped conductive layer 104 is different from the doped ion type in the doped structure 102, and 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 battery cell, and the leakage structure is used to reduce the voltage on the opposite sides of the battery cell, thereby reducing the heat generation power of the battery cell, so as to improve the hot spot phenomenon caused by poor local conductivity of the battery cell.

[0038] 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, 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, 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 receiving the incident light is weaker than the degree of receiving the incident light by the light-receiving surface, and therefore it is defined as a backlight surface.

[0039] In some embodiments, a texturing process may 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, so that the absorption utilization rate of the incident light by the front surface 110 and the back surface 120 of the substrate 100 can be enhanced. In some embodiments, the velvet surface may be a pyramid velvet surface, which, as a common velvet surface, not only reduces the reflectivity of the surface of the substrate 100, but also forms a light trap, thereby enhancing the absorption effect of the substrate 100 on the incident light and improving the photoelectric conversion efficiency of the cell.

[0040] 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 when it is formed, and then a partial covering effect is formed on the back side 120 by removing part of the doping structure 102. Then, when the doping region 106 is formed, part of the doping structure 102 can be removed, so that the problem of the failure of the leakage structure caused by the removal of the entire doping structure 102 can be avoided, thereby improving the fault tolerance of the process.

[0041] In some embodiments, the junction depth of the doping region 106 is 500nm~2μm, for example, 700nm, 900nm, 1.3μm, 1.5μm or 1.8μm, etc. For the doping region 106, the deeper the junction depth of the doping region 106, the stronger the leakage effect of the doping region 106. Similarly, if the junction depth of the doping region 106 is too deep, it will affect the light absorption ability of the battery substrate and cause a large number of carriers to recombine at the corresponding position of the doping region 106, affecting the photoelectric conversion efficiency of the battery. Therefore, by setting the junction depth of the doping region 106 to 500nm~2μm, it is possible to improve the hot spot effect of the battery while avoiding affecting the efficiency of the battery.

[0042] In some embodiments, the substrate 100 includes an edge region and a central region located in the edge region, and the junction depth of the doped region 106 located in the edge region is less than the junction depth of the doped region 106 located in the central region. The edge region of the substrate 100 is the position corresponding to the edge of the substrate 100, and the central region of the substrate 100 is the part located in the center of the substrate 100. Taking a square as an example, the edge region is the partial region adjacent to the edge of the square, and the central region is the partial region surrounded by the edge region. For the edge region of the substrate 100, since it is close to the edge of the battery cell, an effect similar to tip discharge will be generated. Therefore, for the edge region, the junction depth of the doped layer located in the edge region can be reduced to weaken the leakage effect in the edge region, so that the leakage effect of the edge region and the central region can be made relatively uniform, thereby improving the performance of the battery cell.

[0043] 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 may 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, for the orthographic projection of the doping structure 102 on the surface of the substrate 100 to be 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 and the doped conductive layer 104 have the least recombination.

[0044] In some embodiments, the thickness of the doping structure 102 is 0.01 μm to 1 μm, for example, 0.05 μm, 0.2 μm, 0.5 μm, 0.8 μm or 0.95 μm, etc. For the doping structure 102, the thicker the thickness of the doping structure 102, the better the leakage effect brought by the doping structure 102. Similarly, the thicker the thickness of the doping structure 102, the more recombination between the doping structure 102 and the doped conductive layer 104. Therefore, by setting the thickness of the doping structure 102 to 0.01 μm to 1 μm, the leakage effect of the doping structure 102 can be improved while avoiding affecting the efficiency of the battery cell.

[0045] In some embodiments, the size of the doping structure 102 is 1 μm to 100 μm, where the size may 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 farthest 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 μm to 100 μm can also improve the leakage effect of the doping structure 102 while avoiding affecting the efficiency of the battery cell.

[0046] 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 the battery cell carriers.

[0047] 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 greater 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 of the doping structure 102, and 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 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 cell.

[0048] In some embodiments, the doping structures 102 are arranged in an array. By arranging the doping structures 102 in an array, the doping structures 102 can be evenly arranged on the back side 120 of the cell, so that corresponding leakage structures exist at various locations of the cell to improve the hot spot phenomenon of the cell.

[0049] 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 groups 112 are staggered. In other words, the doping structure 102 is composed of multiple sub-doping structures 122, and the uniformity of the arrangement of the leakage structure on the back side 120 of the battery cell can be further improved by setting the sub-doping structures 122 in two adjacent rows to be staggered, so as to further improve the coverage of the doping structure 102 to improve the hot spot phenomenon.

[0050] 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 arranging the sub-doping structures 122 in the doping structure group 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, thereby further improving the reliability of the battery cell.

[0051] In some embodiments, the doping structure 102 includes: a silicon substrate layer containing the first type of doping ions, a silicon compound containing the first type of doping ions, or a silicon oxide containing the first type of doping ions. In other words, the doping structure 102 may be a portion of the substrate 100 converted into the doping structure 102, or an additional layer of the doping structure 102 may be formed on the surface of the substrate 100. Different materials and formation methods may be selected according to different process requirements.

[0052] In some embodiments, the doped conductive layer 104 at least covers a portion of the sidewalls of the doped structure 102. That is, the doped conductive layer 104 can directly contact the doped structure 102, and a leakage structure can be formed by direct contact. By setting the doped conductive layer 104 to at least cover a portion of the sidewalls of the doped structure 102, the leakage capacity of the doped structure 102 can be further improved, and the hot spot effect of the cell can be further improved.

[0053] In some embodiments, the tunneling layer 103 covers the surface of the doped structure 102, the doped conductive layer 104 covers the surface of the tunneling layer 103, and the tunneling layer 103 is spaced between the doped structure 102 and the doped conductive layer 104. By spacing the doped conductive layer 104 from the doped structure 102, the doped structure 102 can be prevented from excessively affecting the photoelectric conversion efficiency of the cell and the performance of the cell.

[0054] The doped conductive layer 104 and the tunneling layer 103 constitute a 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 the majority carriers to tunnel into the doped conductive layer 104 while blocking the recombination of minority carriers, so that the 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.

[0055] In some embodiments, the battery cell also 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.

[0056] In some embodiments, it also includes a front doping layer 108 and a second passivation layer 109 , the front doping layer 108 covers the front side 110 of the substrate 100 , the second passivation layer 109 covers the surface of the front doping layer 108 away from the substrate 100 , and the front electrode 101 is in contact and electrically connected with the front doping layer 108 .

[0057] In some embodiments, the concentration of doped ions in the front doped layer 108 and the doped structure 102 is the same, so that the front doped layer 108 and the doped structure 102 can be formed in the same process step.

[0058] The embodiment of the present disclosure provides a battery cell, which is composed of a substrate 100, a front electrode 101, a tunneling layer 103, a doped conductive layer 104 and a back electrode 105 to form a TOPCON battery, and a doped conductive layer 104 is formed on the back side 120 of the TOPCON battery, and the doped ion type in the doped conductive layer 104 is different from the doped ion type in the doped structure 102, and 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 battery cell, and the leakage structure is used to reduce the voltage on the opposite sides of the battery cell, thereby reducing the heat generation power of the battery cell, so as to improve the hot spot phenomenon caused by poor local conductivity of the battery cell.

[0059] 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.

[0060] refer to Figures 3 to 5 and Figure 1 , Figures 3 to 5 and Figure 1 A schematic structural diagram corresponding to each step of a method for manufacturing a battery cell provided in one embodiment of the present disclosure.

[0061] In some embodiments, the manufacturing method of the battery cell may include: providing a substrate 100 , wherein the substrate 100 includes a front side 110 and a back side 120 opposite to each other.

[0062] The method for manufacturing a battery cell may further include: forming at least one doping structure 102 , wherein the doping structure 102 is located on the back side 120 , and the doping structure 102 contains first type doping ions.

[0063] The method for manufacturing the cell may further include: forming a tunneling layer 103 , wherein the tunneling layer 103 at least covers the back surface 120 and the surface of the doping structure 102 away from the substrate 100 .

[0064] The method for manufacturing the battery cell may further include: forming a doped conductive layer 104 , wherein the doped conductive layer 104 covers the surface of the tunneling layer 103 , and the doped conductive layer 104 contains second type doping ions.

[0065] The method for manufacturing a battery cell may also include: forming a front electrode 101 and a back electrode 105, wherein 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 doped ions are one of N-type doped ions or P-type doped ions, and the second type of doped ions are the other of the N-type doped ions or the P-type doped ions.

[0066] In the process of forming the TOPCON battery, a doping structure 102 is formed on the back side 120, and a leakage channel is formed by the doping structure 102 and the doped conductive layer 104. 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.

[0067] refer to Figure 3 , Figure 3 A morphology of a substrate provided in an embodiment of the present disclosure.

[0068] 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 capacity of the substrate 100 .

[0069] 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 the basis of.

[0070] 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.

[0071] The initial doping structure 132 is formed by first depositing the entire surface, and then the etching selectivity between the laser-processed portion and the non-laser-processed portion changes before and after laser processing. The initial doping structure 132 that has not been laser processed is removed by using the different etching selectivity to complete the formation of the doping structure 102. Compared with directly forming the doping structure 102 on a local area of ​​the back surface 120, the method of removing the initial doping structure 132 after forming it is conducive to reducing the process difficulty, and it is easier to control the position of the doping structure 102, so that the position of the doping structure 102 can be adjusted according to the needs; and the method of forming the doping region 106 in the substrate 100 can also avoid the problem of removing the entire initial doping structure 132 during the etching process, resulting in the failure of the leakage channel.

[0072] In some embodiments, the method for forming the doping structure 102 includes: doping a portion of the substrate 100 to convert the portion of the substrate 100 into an initial doping structure 132; performing laser processing to increase the doping depth of the initial doping structure 132 at a position corresponding to the doping region 106 by laser processing; etching the initial doping structure 132 to remove the initial doping structure 132 that has not been processed by the laser, and the remaining initial doping structure 132 constitutes the doping structure 102. In other words, a portion of the substrate 100 is converted into the initial doping structure 132, and then the junction depth at a position corresponding to the portion of the initial doping structure 132 is increased by laser processing, and then at least the portion of the initial doping layer that has not been processed by the laser is removed by etching to form the doping structure 102.

[0073] The process difficulty of the cell manufacturing method 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 positions through laser processing, it is also easy to control the position of the doping structure 102.

[0074] It can be understood that the junction depth of the corresponding position of part of the initial doping structure 132 can be deepened through laser processing, and the whole surface etching method can be used when etching the initial doping structure 132. Since the junction depth is deeper at the laser-processed position, 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.

[0075] In some embodiments, the initial doping structure 132 may be formed on both the front side 110 and the back side 120 of the substrate 100 by single insertion diffusion, and then laser treatment may be performed only on the back side 120 .

[0076] In some embodiments, after the laser treatment, the following step is further performed: heating treatment is performed to increase the doping junction depth at the corresponding position of the doping structure 102. By further deepening the junction depth at the corresponding position of the doping structure 102, the leakage effect of the doping structure 102 can be further improved on the one hand, and on the other hand, the formation tolerance of the manufacturing method of the battery cell can also be improved, thereby avoiding the removal of the doping structure 102 that needs to be retained while removing the initial doping structure 132, thereby improving the stability of the process.

[0077] 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.

[0078] The first heating step may be a preheating step, by which the ambient temperature of the battery 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 heating 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 heated 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 purposes at the same time, thereby reducing the time the battery cell is in the second heating step.

[0079] 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, etc., 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, etc. By using the first temperature increase step to quickly increase the process temperature of the battery cell to 800°C to 900°C, it is convenient to reach the temperature of the subsequent heating treatment, and by using the second temperature increase step to increase the process temperature of the battery cell to 1000°C to 1200°C, at which temperature, the diffusion of carriers in the battery cell can be facilitated, and while increasing the carrier diffusion speed, the excessive diffusion of carriers can be avoided.

[0080] In some embodiments, the heating rate of the first heating step is 10°C / min~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°C / min~15°C / min can reduce the temperature of the heating 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°C / min~7°C / min can enable the battery cell to complete the diffusion of carriers in a gradually rising temperature 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.

[0081] In some embodiments, the process duration of the heating treatment is 2000s~10000s. As for the process duration of the heating treatment, the longer the process duration of the heating treatment, 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 battery cell. Therefore, by controlling the process duration of the heating treatment to 2000s~10000s, the leakage performance of the initial doping structure 132 can be increased while avoiding affecting the photoelectric conversion efficiency of the battery cell.

[0082] Furthermore, the process duration of the heating treatment is 3000s-7000s. Under this process duration, the leakage performance brought by the initial doping structure 132 and the effect on the photoelectric conversion efficiency of the cell are controlled within a reasonable range.

[0083] In some embodiments, the process parameters of the laser treatment include: the laser type is purple light, green light or red light, the laser frequency is 100KHz~1000KHz, the laser spot diameter is 1μm~100μm, and the laser energy is 1W~500W. Under this process parameter, it is possible to increase the doping junction depth at the corresponding position of the doping structure 102 while avoiding excessive damage to the doping structure 102 caused by the laser treatment, thereby improving the reliability of the formed battery cell.

[0084] 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%.

[0085] The first etching treatment is used to clean the initial doped structure 132 over a large area, thereby completing the purpose of removing the initial doped structure 132. The alkali polishing treatment is used to clean the etching reagents 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 doped structure 132. The second etching treatment can be used to clean the reagents remaining in the alkali polishing treatment, thereby completing the process step of removing the initial doped structure 132.

[0086] In some embodiments, the alkali polishing treatment may be composed of potassium hydroxide, hydrogen peroxide, alkali polishing additives and deionized water.

[0087] 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, followed by 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, a fourth tank water wash can be performed, followed by drying to complete the purpose of removing the initial doping structure 132.

[0088] It is understandable that the purpose of the tank water washing, tank pre-washing, tank post-washing and water washing is to remove the substances generated by the reaction and the carriers remaining on the surface of the substrate 100, thereby improving the reliability of the formed battery cell.

[0089] 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.

[0090] 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 in close contact. 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, and 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.

[0091] After forming the tunneling layer 103 and the doped conductive layer 104, the wrap-around coating layer on the front side 110 and the wrap-around coating layer on the side wall can be etched away. It can be understood that when the doped conductive layer 104 is formed, a wrap-around coating 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 coating layer on the front side 110 and the wrap-around coating layer on the side wall are removed by etching, thereby avoiding affecting the performance of the battery cell.

[0092] It can be understood that, in the process of forming the initial doping layer, since the initial doping layer is also formed on the front side 110 , the initial doping layer located on the front side 110 can be used as the front side doping layer 108 .

[0093] In some embodiments, the method further includes forming a first passivation layer 107 on the front surface 110 and a second passivation layer 109 on the back surface 120. After forming the first passivation layer 107 and the second passivation layer 109 on the front surface 110 and the back surface 120, the front electrode 101 and the back electrode 105 are formed.

[0094] Those skilled in the art can understand that the above-mentioned embodiments are specific examples for implementing the present disclosure, and in practical applications, various changes can 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 can make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure, so the protection scope 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, the substrate comprising a front side and a back side opposite to each other; A front electrode, the front electrode is located on the front side; at least one doping structure, the doping structure being located on the back side and containing first type doping ions; a tunneling layer, the tunneling layer at least covering 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 doping ions; a back electrode, the back electrode being located on the back side and electrically connected to the doped conductive layer; The first type doping ions are one of N-type doping ions and P-type doping ions, and the second type doping ions are the other of N-type doping ions and P-type doping ions.

2. The battery cell according to claim 1, characterized in that: The substrate includes a doping region, wherein the doping region is in contact with and faces the doping structure.

3. The battery cell according to claim 2, characterized in that: 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.

4. The battery cell according to claim 1, characterized in that: The doped conductive layer at least covers a portion of the sidewall of the doped structure.

5. The battery cell according to claim 1, characterized in that: The doping structure includes a plurality of rows of doping structure groups, each row of the doping structure group includes a plurality of sub-doping structures, and the sub-doping structures in two adjacent rows of the doping structure groups are staggered with each other.

6. A method for manufacturing a battery cell, characterized in that: include: Providing a substrate, the substrate comprising a front side and a back side opposite to each other; forming at least one doping structure, wherein the doping structure is located on the back side and contains first type doping ions; forming a tunneling layer, wherein the tunneling layer at least covers the back surface and a surface of the doping 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 doping ions; forming a front electrode and a back electrode, wherein the front electrode is located on the front side, and the back electrode is located on the back side and is electrically connected to the doped conductive layer; The first type doping ions are one of N-type doping ions and P-type doping ions, and the second type doping ions are the other of N-type doping ions and P-type doping ions.

7. The method for manufacturing a battery cell according to claim 6, characterized in that: The method of 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 to convert part of the initial doping structure into the doping structure and form a doping 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, characterized in that: The method of forming the doping 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; The initial doping structure is etched to remove the initial doping structure that has not been 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, characterized in that: Heat treatment includes: A first temperature increasing step, wherein the first temperature increasing step is used to increase the temperature of the heating treatment to a first preset temperature; A second temperature increasing step, wherein the second temperature increasing step is used to increase 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.

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