Battery piece and photovoltaic module

Abstract

The invention discloses a battery piece and a photovoltaic module, and the battery piece comprises a silicon substrate, the surface of which comprises a plurality of grooves; a doping layer is arranged on the surface of the silicon substrate, and the doping layer partially covers the groove; a plurality of fine gate electrodes are further arranged on the doping layer, the fine gate electrodes are electrically connected with the doping layer, and the extending direction of the grooves intersects with the extending direction of the fine gate electrodes; wherein the fine grid electrode comprises first part fine grids and second part fine grids which are alternately arranged and connected with each other, the second part fine grids are located at the intersection of the fine grid electrode and the groove, and the width of the second part fine grids is larger than that of the adjacent first part fine grids. According to the embodiment of the invention, the second part of the fine grid at the intersection of the fine grid electrode and the groove is widened, so that the second part of the fine grid has stronger carrier collection capability, dense carriers can be collected, and the efficiency of the cell is improved.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a cell and a photovoltaic module. Background Art

[0002] A photovoltaic module includes several cells, each of which has several fine grids to collect photocurrent.

[0003] Traditional solutions have always suffered from the problem of poor carrier collection ability of fine gates. Therefore, how to refine and improve the carrier collection ability of fine gates is an urgent problem to be solved. Summary of the Invention

[0004] The present invention provides a solar cell and a photovoltaic module, aiming to improve the carrier collection capability of a fine grid in a refined manner.

[0005] An embodiment of the present invention provides a battery cell, including: A silicon substrate, wherein a surface of the silicon substrate comprises a plurality of grooves; A doping layer is provided on the surface of the silicon substrate, and the doping layer partially covers the groove; A plurality of fine gate electrodes are further provided on the doped layer, the fine gate electrodes are electrically connected to the doped layer, and an extension direction of the trench intersects with an extension direction of the fine gate electrodes; The fine gate electrode includes a first portion of fine gates and a second portion of fine gates that are alternately arranged and interconnected. The second portion of fine gates is located at the intersection of the fine gate electrode and the groove. The width of the second portion of fine gates is greater than the width of the adjacent first portion of fine gates.

[0006] In an embodiment of the present invention, the doped layer is positioned at the location of the groove, conforming to and covering the groove as the groove is recessed, resulting in a doped layer on both the sidewalls and bottom wall of the groove. This increases the contact area between the doped layer and the silicon substrate along the groove, reducing the contact resistance between the doped layer and the silicon substrate in the groove region, thereby increasing the density of carriers along the groove. Therefore, the second portion of the fine gate at the intersection of the fine gate electrode and the groove is widened, giving the second portion of the fine gate a stronger carrier collection capability, thereby collecting dense carriers and improving the efficiency of the cell.

[0007] Optionally, several of the grooves are divided into first grooves and second grooves, and several of the fine gate electrodes are divided into first fine gate electrodes and second fine gate electrodes. The extension direction of the first groove intersects with the extension direction of the first fine gate electrode, and the extension direction of the second groove intersects with the extension direction of the second fine gate electrode. The recess depth of the first groove is greater than the recess depth of the second groove. The difference between the width of the second part of the fine gate of the first fine gate electrode and the width of the adjacent first part of the fine gate is S1, the width of the first part of the fine gate of the first fine gate electrode is W1, the difference between the width of the second part of the fine gate of the second fine gate electrode and the width of the adjacent first part of the fine gate is S2, the width of the first part of the fine gate of the second fine gate electrode is W2, and the ratio of S1 to W1 is greater than the ratio of S2 to W2.

[0008] Optionally, a texture structure is provided in the groove, and the texture structure is a tower base structure or a pyramid structure.

[0009] Optionally, a difference between a width of the second portion of the fine gate and a width of an adjacent first portion of the fine gate is S, a width of a first portion of the fine gate adjacent to the second portion of the fine gate is W, and S is 10%W-80%W.

[0010] Optionally, S is 30%W-60%W.

[0011] Optionally, the texture structure is a tower-shaped structure that is concave toward the silicon substrate; The battery cell has a first area and a second area, the groove located in the first area is a third groove, the groove located in the second area is a fourth groove, and a one-dimensional size of the texture structure in the third groove is larger than a one-dimensional size of the texture structure in the fourth groove; The fine gate electrode located in the first region is a third fine gate electrode, the fine gate electrode located in the second region is a fourth fine gate electrode, an extension direction of the third trench intersects with an extension direction of the third fine gate electrode, and an extension direction of the fourth trench intersects with an extension direction of the fourth fine gate electrode; The difference between the width of the second portion of the fine gate of the third fine gate electrode and the width of the adjacent first portion of the fine gate is S3, the width of the first portion of the fine gate of the third fine gate electrode is W3, the difference between the width of the second portion of the fine gate of the fourth fine gate electrode and the width of the adjacent first portion of the fine gate is S4, the width of the first portion of the fine gate of the fourth fine gate electrode is W3, and the ratio of S3 to W3 is greater than the ratio of S4 to W4.

[0012] Optionally, the cell is a back-contact cell; a direction in which the plurality of fine gate electrodes are arranged at intervals is a first direction, and along the first direction, the back side of the cell has N-type doped regions and P-type doped regions arranged alternately; The first region is the N-type doping region, the second region is the P-type doping region, and the width of the second portion of the fine gate in the N-type doping region is greater than the width of the second portion of the fine gate in the P-type doping region.

[0013] Optionally, the cell is a bifacial cell, and the surface of the silicon substrate is the front side and / or the back side.

[0014] Optionally, the first portion of the fine gate has a first surface facing away from the silicon substrate, the second portion of the fine gate has a second surface facing away from the silicon substrate, and along the thickness direction of the battery cell, the height of the first portion of the fine gate is H1, the distance between the second surface and the first surface is H2, and 0≤H2≤0.5H1.

[0015] Optionally, at the intersection of the trench and the fine gate electrode, an angle between the trench and the fine gate electrode is 70°-115°.

[0016] Optionally, the width of the first portion of fine gates is 25 μm-50 μm; and / or the width of the second portion of fine gates is 6 μm-54 μm.

[0017] Optionally, the battery cell further includes a connecting portion, and the connecting portion is used to be electrically connected to the electrical connector; The connecting portion is continuously or discontinuously arranged on the groove, and an extending direction of the connecting portion is perpendicular to the fine gate electrode.

[0018] Optionally, the width of the groove is 15 μm-50 μm; and / or the depth of the groove is 0.1 μm-30 μm.

[0019] An embodiment of the present invention further provides a photovoltaic assembly comprising a plurality of battery strings connected in series and / or in parallel, wherein the battery string comprises an electrical connector and the battery cells described above, wherein the electrical connector electrically connects at least two of the battery cells.

[0020] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the structure of a battery cell provided in an embodiment of the present invention; Figure 2 for Figure 1 A magnified schematic diagram of point A in the middle; Figure 3 A schematic diagram of the structure of the trench and fine gate electrode in the cell provided by an embodiment of the present invention; Figure 4 A schematic diagram of the structure of the trench and fine gate electrode in a cell provided by another embodiment of the present invention; Figure 5 A schematic diagram of the microscopic morphology of a battery cell provided in an embodiment of the present invention; Figure 6 A partial cross-sectional schematic diagram of a battery cell provided in an embodiment of the present invention.

[0022] Reference numerals: Solar cell, 11-silicon substrate, 12-doped layer, 13-fine gate electrode, 131-first portion of fine gate, 1311-first surface, 132-second portion of fine gate, 1321-second surface, 1322-recess, 14-groove, 15-texture structure. DETAILED DESCRIPTION

[0023] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0024] Reference Figures 1 to 6 An embodiment of the present invention provides a cell 10, comprising: a silicon substrate 11, wherein the surface of the silicon substrate 11 includes a plurality of grooves 14; a doped layer 12 is provided on the surface of the silicon substrate 11, the doped layer 12 partially covering the grooves 14, and a plurality of fine gate electrodes 13 are further provided on the doped layer 12, the fine gate electrodes 13 are electrically connected to the doped layer 12, and the extension direction of the grooves 14 intersects with the extension direction of the fine gate electrodes 13; wherein the fine gate electrodes 13 include first and second portions of fine gates 131 and 132 that are alternately arranged and interconnected, the second portions of fine gates 132 being located at the intersection of the fine gate electrodes 13 and the grooves 14, and on the same fine gate electrode 13, the width of the second portions of fine gates 132 is greater than the width of the adjacent first portions of fine gates 131.

[0025] like Figure 6As shown, the doped layer 12 is formed at the location of the groove 14 as the groove 14 is recessed and covers the groove 14, so that the doped layer 12 is provided on both the sidewalls and the bottom wall of the groove 14. In other words, the contact area between the doped layer 12 and the silicon substrate 11 along the groove 14 increases, thereby reducing the contact resistance between the doped layer 12 and the silicon substrate 11 in the groove 14 region, thereby making the carriers along the groove 14 more dense. Therefore, the second portion of the fine gate 132 at the intersection of the fine gate electrode 13 and the groove 14 is widened, so that the second portion of the fine gate 132 has a stronger carrier collection capability, thereby being able to collect dense carriers and improve the efficiency of the cell 10.

[0026] In addition, compared with widening the entire fine gate, the local widening of the fine gate electrode 13 can reduce the amount of slurry used in the fine gate electrode 13, thereby reducing costs.

[0027] It is understood that the cell 10 can be a busbar-less cell, that is, the cell 10 has a fine grid electrode 13 and eliminates the busbar, which can save the slurry consumed by the busbar, thereby reducing the cost of the module. The cell 10 can also be a busbar-equipped cell. The cell 10 can be a whole cell, a half cell, or other multi-cell cell, which is not limited in this application.

[0028] It should be noted that the silicon substrate 11 is formed by processing silicon wafers, and the above-mentioned processing includes but is not limited to wet or dry processing such as cleaning, polishing, and texturing. The silicon wafer is cut from the silicon rod, and the silicon rod is specifically cut by a cutting wire. The groove in the present application can be the line mark formed on the silicon wafer during the cutting process of the cutting wire, which is the mark left during the battery manufacturing process. The cutting wire can be a diamond wire. In the related art, when the cutting wire cuts the silicon rod, the long side of the cross section of the silicon rod is the cutting surface. The groove formed after cutting in this way is basically parallel to the fine grid set subsequently. In this embodiment, when the cutting wire cuts the silicon rod, the short side of the cross section of the silicon rod is the cutting surface. This method makes the groove formed after cutting intersect with the fine grid set subsequently, for example, basically perpendicular. Among them, the fine gate electrode 13 has a larger width at the intersection with the groove 14, which can be achieved by controlling the width and / or depth of the groove 14 (detailed description in the following embodiment), and the degree of wetting of the groove surface with the slurry. Alternatively, the width of the intersection of the fine gate electrode 13 and the trench 14 is larger, or different widths in different regions can be achieved by using a mask or the like.

[0029] In some embodiments, the cell 10 is a back-contact cell, with both the positive and negative electrodes located on its back surface, with the surface of the silicon substrate 11 being the back surface. In some embodiments, the cell 10 is a bifacial cell, with the surface of the silicon substrate 11 being the front surface and / or back surface. In a bifacial cell, one of the positive and negative electrodes is located on the front surface, and the other is located on the back surface.

[0030] The doping layer 12 refers to a layer formed by introducing a small amount of other elements (such as phosphorus or boron) into a semiconductor material (such as silicon) to change its conductivity. The purpose of doping is to control the conductivity of the semiconductor. The plurality of fine gate electrodes 13 may include a plurality of positive fine gate electrodes 13 and a plurality of negative fine gate electrodes 13. The plurality of positive fine gate electrodes 13 and the plurality of negative fine gate electrodes 13 may be arranged alternately along a first direction. The first direction can refer to Figure 1 、 Figures 3 to 5 Alternatively, the positive fine gate electrode 13 and the plurality of negative fine gate electrodes 13 can be distributed on the front or back surface, respectively. The widths of the first portion of the fine gates 131 in the positive fine gate electrode 13 and the negative fine gate electrode 13 can be different or the same.

[0031] It should be noted that the extension direction of the fine gate electrode 13 can refer to Figure 1 、 Figures 3 to 6 The direction is indicated by the arrow B. Along the extension direction of the fine gate electrode 13, the trench 14 has a first side and a second side opposite to each other. The boundary line between the second fine gate portion 132 and the first fine gate portion 131 on one side corresponds to the first side, and the boundary line between the second fine gate portion 132 and the first fine gate portion 131 on the other side corresponds to the second side.

[0032] It is understood that the width of the second portion of the fine grid 132 can refer to its maximum width, and the width of the first portion of the fine grid 131 adjacent to the second portion of the fine grid 132 can refer to its maximum width, its average width, or the width at a specific point. For a second portion of the fine grid 132 near the edge of the cell, the number of adjacent first portion of the fine grid 131 can be one. For other second portion of the fine grid 132 not at the edge, the number of adjacent first portion of the fine grid 131 is two. In this case, the width of the first portion of the fine grid 131 adjacent to the second portion of the fine grid 132 can refer to the width of a cross section at a specific point on any first portion of the fine grid 131, or the average width of the cross sections at any point on the two first portion of the fine grid 131.

[0033] In some embodiments, a plurality of grooves are divided into first grooves and second grooves, a plurality of fine gate electrodes are divided into first fine gate electrodes and second fine gate electrodes, an extension direction of the first groove intersects with an extension direction of the first fine gate electrode, and an extension direction of the second groove intersects with an extension direction of the second fine gate electrode; a recess depth of the first groove is greater than a recess depth of the second groove, a difference between a width of the second portion of the fine gate of the first fine gate electrode and a width of an adjacent first portion of the fine gate is S1, a width of the first portion of the fine gate of the first fine gate electrode is W1, a difference between a width of the second portion of the fine gate of the second fine gate electrode and a width of the adjacent first portion of the fine gate is S2, a width of the first portion of the fine gate of the second fine gate electrode is W2, and a ratio of S1 to W1 is greater than a ratio of S2 to W2.

[0034] The depth of the groove 14 can be 0.1 μm to 30 μm, preferably 0.1 μm to 3 μm. A groove with a depth greater than or equal to 0.1 μm and less than X μm can be defined as a first groove, and a groove with a depth greater than X μm and less than or equal to 30 μm can be defined as a second groove. X can be set according to actual needs, for example, 1.5 μm, 2 μm, etc.

[0035] The ratio of S1 to W1 can represent the width of the second portion of the fine gate 132 of the first fine gate electrode wider than the width of the adjacent first portion of the fine gate 131, and the ratio of S2 to W2 can represent the width of the second portion of the fine gate 132 of the second fine gate electrode wider than the width of the adjacent first portion of the fine gate 131.

[0036] The resistivity of the portion of the doped layer corresponding to the deep trench is relatively small, and the conductivity is relatively large. Along the extension direction of the fine gate electrode 13, the carriers on both sides of the deep trench can migrate laterally to the portion of the doped layer corresponding to the deep trench. The lateral migration path of the carriers on both sides of the deep trench can be referred to Figure 5 The path shown by the dotted arrow is then vertically transmitted along the first direction to the fine gate electrode 13 in this portion, that is, the second portion of the fine gate 132 where the fine gate electrode 13 intersects the deep trench will collect more current.

[0037] In this embodiment, the depression depth of the first groove is greater than the depression depth of the second groove, that is, compared with the second groove, the first groove is a deep groove, and the resistivity of the portion of the doping layer corresponding to the first groove is relatively small, and the conductivity is relatively large. Along the extension direction of the fine gate electrode 13, the carriers on both sides of the first groove may migrate laterally to the portion of the doping layer corresponding to the first groove (for example, the carriers of the second groove may be transmitted laterally to the doping layer corresponding to the first groove), and then be vertically transmitted along the first direction in this portion to the first fine gate electrode, that is, there are more dense carriers at the second portion of the fine gate 132 intersecting with the first groove. The second portion of the fine gate 132 at the intersection of the first fine gate electrode and the first trench is wider than the second portion of the fine gate 132 at the intersection of the second fine gate electrode and the second trench. When W1 and W2 are equal, the second portion of the fine gate 132 at the intersection of the first fine gate electrode and the first trench is wider than the second portion of the fine gate 132 at the intersection of the second fine gate electrode and the second trench. This allows the second portion of the fine gate 132 at the intersection of the first fine gate electrode and the first trench to collect more carriers, thereby collecting more densely packed carriers. Therefore, this embodiment can further refine and improve the carrier collection capability of the fine gate, thereby increasing the efficiency of the cell.

[0038] It is understandable that if Figure 4As shown, the first fine gate electrode and the second fine gate electrode can be the same fine gate electrode 13. This can be understood as the widening amplitude of the intersection with the deep trench in the same fine gate electrode 13 is greater than the widening amplitude of the intersection with the shallow trench.

[0039] In some embodiments, a texture structure 15 is provided in the groove 14 , and the texture structure 15 is a tower base structure or a pyramid structure.

[0040] By providing a texture structure 15 corresponding to the groove 14, the flow of the slurry in the groove 14 can be restricted, thereby preventing the intersection of the fine gate electrode 13 and the groove 14 from widening too much and avoiding excessive light blocking. The groove 14 can be a strip-shaped groove structure, and the texture structure 15 is formed on the bottom wall of the groove 14. Alternatively, the texture structure can be formed on the side wall, which is not limited in this application. The texture structure can be a tower base structure or a pyramid structure.

[0041] It is understood that when the cell 10 is a bifacial cell, the texture structure 15 within the groove 14 where the front surface of the silicon substrate 11 intersects the fine gate electrode 13 can be a pyramid-shaped structure, and the texture structure 15 within the groove 14 where the back surface of the silicon substrate 11 intersects the fine gate electrode 13 can be a tower-shaped structure. When the cell is a back-contact cell, the texture structure 15 within the groove 14 where the back surface of the silicon substrate 11 intersects the fine gate electrode 13 can be a tower-shaped structure. It is understood that the surface non-groove area of ​​the silicon substrate 11 can also be provided with a texture structure.

[0042] It should be noted that in this embodiment, the tower base can be a polished surface, or a pit structure, or can also be a tower base-like structure with a smaller platform protruding from the silicon substrate 11, and this application is not limited to this. The pyramid structure can be a pyramid with a sharp top angle, a pyramid-like structure with rounded chamfers, or a pyramid-like structure with flattened top angles.

[0043] It can also be understood that when the texture structure 15 is a tower base structure, there are multiple texture structures that are at least partially stacked along the first direction, and there are also individual texture structures 15.

[0044] In some embodiments, on the same fine gate electrode 13 , the difference between the width of the second portion of the fine gate 132 and the width of the adjacent first portion of the fine gate 131 is S, the width of the first portion of the fine gate 131 adjacent to the second portion of the fine gate 132 is W, and S is 10%W-80%W.

[0045] S can be 10%W, 20%W, 30%W, 50%W, 60%W, 80%W, etc. A smaller S indicates that the widening of the intersection of the fine gate electrode 13 and the trench 14 is small, which is not conducive to carrier collection. A larger S indicates that the widening of the intersection of the fine gate electrode 13 and the trench 14 is large, which is not conducive to ensuring the straightness of the fine gate electrode 13 and increases the light shielding area. When S is within the above range, while achieving strong carrier collection capability at this location, the straightness of the fine gate electrode 13 is ensured and excessive light shielding is avoided.

[0046] In some embodiments, S is 30%W-60%W. S can be 30%W, 40%W, 50%W, 60%W, etc. In this embodiment, the widening range at the intersection of the fine gate electrode 13 and the trench 14 is further optimized to further ensure the straightness of the fine gate electrode 13 while achieving a stronger carrier collection capability at this location and avoiding excessive light blocking.

[0047] In some embodiments, the texture structure 15 is a tower-shaped structure recessed toward the silicon substrate 11; the cell has a first region and a second region, the groove 14 located in the first region is a third groove, the groove 14 located in the second region is a fourth groove, and the one-dimensional size of the texture structure 15 in the third groove is greater than the one-dimensional size of the texture structure 15 in the fourth groove; the fine gate electrode 13 located in the first region is a third fine gate electrode, the fine gate electrode 13 located in the second region is a fourth fine gate electrode, and the extension direction of the third groove and the extension direction of the third fine gate electrode are the same. The extension direction of the fourth trench intersects with the extension direction of the fourth fine gate electrode; the difference between the width of the second portion of the fine gate 132 of the third fine gate electrode and the width of the adjacent first portion of the fine gate 131 is S3, the width of the first portion of the fine gate 131 of the third fine gate electrode is W3, the difference between the width of the second portion of the fine gate 132 of the fourth fine gate electrode and the width of the adjacent first portion of the fine gate 131 is S4, the width of the first portion of the fine gate 131 of the fourth fine gate electrode is W3, and the ratio of S3 to W3 is greater than the ratio of S4 to W4.

[0048] The ratio of S3 to W3 can represent the extent to which the width of the second portion of the fine gate 132 of the third fine gate electrode is wider than the width of the adjacent first portion of the fine gate 131 within the first region. The ratio of S4 to W4 can represent the extent to which the width of the second portion of the fine gate 132 of the fourth fine gate electrode is wider than the width of the adjacent first portion of the fine gate 131 within the second region. In this embodiment, the larger the one-dimensional dimension of the tower-shaped structure recessed toward the silicon substrate 11, the greater the width of the corresponding second portion of the fine gate 132. By controlling the one-dimensional dimension of the texture structure 15, the width of the second portion of the fine gate 132 can be controlled (for example, the boundaries of the texture structure can control the flow of the gate line paste), thereby more precisely controlling the carrier collection capacity of different gate line regions, thereby improving the efficiency of the cell 10.

[0049] For example, the first region may be an N-type doped region 16, and the second region may be a P-type doped region 17. It is understood that the shape of the tower-shaped structure recessed toward the silicon substrate 11 may be a rhombus, and its one-dimensional size may refer to the diagonal length of the tower-shaped structure or the length of its side.

[0050] For another example, S3 is 30% W3-60% W3; S4 is 20% W4-50% W4. S3 can be 30% W3, 40% W3, 50% W3, 60% W3, and so on. S4 can be 20% W4, 30% W4, 35% W4, 40% W4, 50% W4, and so on. In this embodiment, the widening range at the intersection of the fine gate electrode 13 and the trench 14 is further optimized. This ensures the straightness of the fine gate electrode 13 while achieving strong carrier collection capability at the intersection of the fine gate electrode 13 and the trench 14, and avoids excessive light blocking.

[0051] It should be noted that the width of the groove 14 can be the same as the size of the texture structure 15 , that is, one texture structure 15 is provided within the width of the groove 14 .

[0052] It should also be noted that this embodiment can be combined with the above embodiments. For example, by controlling the depth of the groove and the size of the tower base in the groove (or the width of the groove), the width of the groove can be adjusted together.

[0053] In some embodiments, the cell 10 is a back-contact cell; the direction in which a plurality of fine gate electrodes 13 are arranged at intervals is a first direction, and along the first direction, the back side of the cell 10 has alternatingly arranged N-type doping regions and P-type doping regions; the first region is an N-type doping region, and the second region is a P-type doping region; the width of the second portion of the fine gate 132 in the N-type doping region is greater than the width of the second portion of the fine gate 132 in the P-type doping region.

[0054] In a back-contact cell, both the positive and negative electrodes are located on its back side, while the front side has no electrodes. This allows for higher light utilization on the light-facing side of the back-contact cell. Back-contact cells also feature low shading loss and an aesthetically pleasing appearance. When the cell 10 is a back-contact cell, the textured structure 15 in the P-type and N-type doped regions on its back side is a tower-like structure. Adjacent P-type and N-type doped regions are separated by an undoped isolation region (which may have a tower-like or pyramid-like structure). The width of the first portion of the fine gate 131 in the N-type doped region can be greater than the width of the first portion of the fine gate 131 in the P-type doped region. Furthermore, the width of the intersection of the fine gate electrode 13 corresponding to the N-type doped region and the trench 14 is greater than the width of the intersection of the fine gate electrode 13 corresponding to the P-type doped region and the trench 14. Consequently, the width of the second portion of the fine gate 132 in the N-type doped region is greater than the width of the second portion of the fine gate 132 in the P-type doped region. For cells with an N-type substrate, the N-type doping region typically has a higher doping concentration and lower recombination, resulting in more carriers in the N-type doping region. This embodiment can enhance the carrier collection capability of the second portion of the fine gate 132 corresponding to the N-type doping region, thereby enabling the collection of more carriers in the N-type doping region.

[0055] In some embodiments, reference Figure 6 The first portion of the fine gate 131 has a first surface 1311 facing away from the silicon substrate 11, and the second portion of the fine gate 132 has a second surface 1321 facing away from the silicon substrate 11. Along the thickness direction of the battery cell, the height of the first portion of the fine gate 131 is H1, and the distance between the second surface 1321 and the first surface 1311 is H2, 0≤H2≤0.5H1.

[0056] The thickness direction of the battery cell can be referred to Figure 6 The direction indicated by the arrow D in FIG. H2 is preferably less than 0.4H1. In this embodiment, the second surface 1321 of the second portion of the fine grid 132 is substantially flush with the first surface 1311 of the first portion of the fine grid 131, or the second surface 1321 of the second portion of the fine grid 132 is shallower than the first surface 1311 of the first portion of the fine grid 131, thereby preventing the second surface 1321 of the second portion of the fine grid 132 from being too recessed and causing the fine grid to break.

[0057] In some embodiments, reference Figure 6 The second portion of the fine gate 132 has a recessed portion 1322 that is recessed toward the silicon substrate 11. The recessed portion 1322 increases the contact area between the fine gate electrode 13 and the silicon substrate 11, thereby improving the current collection capability and the photoelectric conversion efficiency of the cell.

[0058] In some possible embodiments, reference Figures 2 to 5At the intersection of the trench 14 and the fine gate electrode 13 , the angle between the trench 14 and the fine gate electrode 13 can be 25°-155°, 45°-135°, or 70°-115°.

[0059] The angle between the groove 14 and the fine gate electrode 13 can be 70°, 80°, 85°, 90°, 95°, 100°, 115°, etc. The extension direction of the groove 14 is substantially perpendicular to the extension direction of the fine gate electrode 13, that is, the angle between the groove 14 and the fine gate electrode 13 is approximately 90°. The extension direction of the fine gate electrode 13 is consistent with the length direction of the cell. In this embodiment, when the angle between the groove 14 and the fine gate electrode 13 is within the above range, the length of the groove 14 is relatively short, and the effective cutting length of the cutting line 30 for cutting the silicon rod 20 is relatively short, which is beneficial for improving the surface quality of the cut silicon wafer. In addition, the fine gate electrode 13 intersects the groove 14, allowing carriers to be transmitted along the groove direction to the widened second portion of the fine gate 132. Compared with the arrangement where the fine gate electrode 13 is parallel to the groove 14 and the overlap between the fine gate electrode 13 and the groove 14 is widened, excessive light blocking by the fine gate electrode 13 can be reduced. In addition, the angle between the trench 14 and the fine gate electrode 13 is set at 70°-115°, which can shorten the transmission distance of carriers in the doping layer 12 attached to the trench 14, thereby further improving the carrier collection capability.

[0060] In some embodiments, the width of the first portion of the fine gates 131 is 5 μm-50 μm, and the width of the second portion of the fine gates is 6 μm-54 μm.

[0061] The width of the first portion of the fine grid 131 can be 5 μm, 8 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, 50 μm, etc. The width of the second portion of the fine grid 132 can be 6 μm, 8 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, 50 μm, 51 μm, 53 μm, 54 μm, etc. The first portion of the fine grid 131 has a certain width to reduce the possibility of gate breakage and ensure current collection capability. In addition, the width of the first portion of the fine grid 131 is less than or equal to 50 μm, which can avoid the increase in cost and increase in light shielding area caused by excessive width. The width of the second portion of the fine grid 132 is greater than that of the adjacent first portion of the fine grid 131, and the width of the second portion of the fine grid is less than or equal to 54 μm, which can avoid the increase in cost and increase in light shielding area caused by excessive width.

[0062] In some embodiments, the cell further includes a connecting portion, which is used to electrically connect to an electrical connector. The connecting portion is continuously or discontinuously arranged on the groove 14 , and an extending direction of the connecting portion is perpendicular to the fine gate electrode 13 .

[0063] Among them, when the battery cell is a busbar-less battery cell, the connecting portion can be a welding point (or called a "pad") on the fine gate electrode 13, and the connecting portion can be intermittently attached to the groove 14. When the battery cell is a busbar-equipped battery cell, the connecting portion is the main gate electrode, and the connecting portion is continuously attached to the groove 14. The pad on the fine gate electrode 13 can be directly connected to the electrical connector, and the main gate electrode can be connected to the electrical connector through the pad. The connecting portion is used to transmit carriers collected from the fine gate electrode 13, and the extension direction of the connecting portion can be set parallel to the groove 14. In this way, the attachment of the connecting portion to the groove 14 can increase the area of ​​the connecting portion, thereby improving the carrier transmission capacity of the connecting portion.

[0064] In addition, multiple battery cells 10 are connected in series to form a battery string through electrical connectors. The electrical connectors can be welding strips or film-coated welding strips, conductive backplanes, etc. The welding strips can be flat welding strips or round wire welding strips. The welding strips can also be set to other shapes according to actual needs. In this embodiment, the connecting portion is continuously or intermittently arranged on the groove 14, which can increase the attachment area of ​​the connecting portion, thereby increasing the pulling force between the electrical connector and the battery cell 10 to meet the reliability requirements of the photovoltaic module. Among them, the pulling force between the electrical connector and the battery cell 10 refers to the force required to pull the electrical connector off the battery cell 10.

[0065] In some embodiments, the width of the trench 14 is 15 μm to 50 μm. For example, the width of the trench 14 can be 15 μm, 18 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 48 μm, or 50 μm. A trench 14 width exceeding 50 μm will affect the layout of the fine gate electrode 13. A trench 14 width less than 15 μm will result in a narrower width for the fine gate electrode 13, which will weaken the carrier collection capability.

[0066] In some embodiments, the depth of the groove 14 is 0.1 μm to 30 μm. For example, the depth of the groove 14 can be 0.1 μm, 0.5 μm, 1 μm, 2 μm, 4 μm, 8 μm, 10 μm, 15 μm, 20 μm, 25 μm, 28 μm, or 30 μm. The depth of the groove 14 is preferably 0.1 μm to 3 μm. If the depth of the groove 14 exceeds 30 μm, the surface of the battery cell 10 will be too uneven, affecting the passivation effect of the surface. If the depth of the groove 14 is less than 0.1 μm, the width of the widened fine gate electrode 13 will be too small, and the ability to enhance the carrier collection capability will be too weak.

[0067] In some embodiments, the direction in which the plurality of fine gate electrodes 13 are arranged at intervals is the first direction, the extension direction of the fine gate electrodes 13 is the second direction, the ratio of the length of the battery cell 10 along the second direction to the width of the battery cell along the first direction is 1.5-2.6; the length of the battery cell 10 along the second direction is 182mm-230mm; the width of the battery cell 10 along the first direction is 91mm-230mm.

[0068] The ratio of the length of the battery cell 10 along the second direction to the width of the battery cell 10 along the first direction can be 1, 1.5, 2, 2.53, 2.6, etc. The length of the battery cell 10 along the second direction can be 182 mm, 192 mm, 210 mm, 230 mm, etc. The width of the battery cell 10 along the first direction can be 91 mm, 105 mm, 182 mm, 230 mm, etc.

[0069] In some embodiments, the fine gate electrode 13 is a continuous fine gate electrode 13. In this case, compared with the interrupted fine gate electrode 13, the continuous fine gate electrode 13 has a better current collection effect.

[0070] An embodiment of the present invention further provides a photovoltaic module, which includes a plurality of battery strings connected in series and / or in parallel. The battery string includes: an electrical connector and the above-mentioned battery cells 10 , and the electrical connector electrically connects at least two battery cells 10 .

[0071] A photovoltaic module consists of a stacked backsheet, a backside adhesive film, multiple cell strings, a frontside adhesive film, and front glass. Each cell string consists of multiple cells and electrical connectors that connect the cells in series. The electrical connectors are electrically connected to the connecting parts of the cells. The adhesive film can be made of materials such as EVA (ethylene-vinyl acetate copolymer), POE (polyolefin elastomer), or EPE (expanded polyethylene). The front glass can be tempered, semi-tempered, or patterned glass. The backsheet can be white or glass.

[0072] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0073] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the purpose and scope of protection of the present invention, which are all protected by the present invention.

Claims

1. A battery cell, characterized in that: include: A silicon substrate, wherein a surface of the silicon substrate comprises a plurality of grooves; A doping layer is provided on the surface of the silicon substrate, and the doping layer partially covers the groove; A plurality of fine gate electrodes are further provided on the doped layer, the fine gate electrodes are electrically connected to the doped layer, and an extension direction of the trench intersects with an extension direction of the fine gate electrodes; The fine gate electrode includes a first portion of fine gates and a second portion of fine gates that are alternately arranged and interconnected. The second portion of fine gates is located at the intersection of the fine gate electrode and the groove. The width of the second portion of fine gates is greater than the width of the adjacent first portion of fine gates.

2. The battery cell according to claim 1, wherein: Several of the grooves are divided into first grooves and second grooves, and several of the fine gate electrodes are divided into first fine gate electrodes and second fine gate electrodes. The extension direction of the first groove intersects with the extension direction of the first fine gate electrode, and the extension direction of the second groove intersects with the extension direction of the second fine gate electrode. The recess depth of the first groove is greater than the recess depth of the second groove. The difference between the width of the second part of the fine gate of the first fine gate electrode and the width of the adjacent first part of the fine gate is S1, the width of the first part of the fine gate of the first fine gate electrode is W1, the difference between the width of the second part of the fine gate of the second fine gate electrode and the width of the adjacent first part of the fine gate is S2, the width of the first part of the fine gate of the second fine gate electrode is W2, and the ratio of S1 to W1 is greater than the ratio of S2 to W2.

3. The battery cell according to claim 1, wherein: A texture structure is provided in the groove, and the texture structure is a tower base structure or a pyramid structure.

4. The battery cell according to claim 1, wherein: The difference between the width of the second portion of the fine gate and the width of the adjacent first portion of the fine gate is S, the width of the first portion of the fine gate adjacent to the second portion of the fine gate is W, and S is 10%W-80%W.

5. The battery cell according to claim 4, characterized in that: S is 30%W-60%W.

6. The battery cell according to claim 3, characterized in that: The texture structure is a tower-shaped structure that is concave toward the silicon substrate; The battery cell has a first area and a second area, the groove located in the first area is a third groove, the groove located in the second area is a fourth groove, and a one-dimensional size of the texture structure in the third groove is larger than a one-dimensional size of the texture structure in the fourth groove; The fine gate electrode located in the first region is a third fine gate electrode, the fine gate electrode located in the second region is a fourth fine gate electrode, an extension direction of the third trench intersects with an extension direction of the third fine gate electrode, and an extension direction of the fourth trench intersects with an extension direction of the fourth fine gate electrode; The difference between the width of the second portion of the fine gate of the third fine gate electrode and the width of the adjacent first portion of the fine gate is S3, the width of the first portion of the fine gate of the third fine gate electrode is W3, the difference between the width of the second portion of the fine gate of the fourth fine gate electrode and the width of the adjacent first portion of the fine gate is S4, the width of the first portion of the fine gate of the fourth fine gate electrode is W3, and the ratio of S3 to W3 is greater than the ratio of S4 to W4.

7. The battery cell according to claim 6, characterized in that: The cell is a back-contact cell; the direction in which the fine gate electrodes are arranged at intervals is a first direction, and along the first direction, the back side of the cell has N-type doped regions and P-type doped regions arranged alternately; The first region is the N-type doping region, the second region is the P-type doping region, and the width of the second portion of the fine gate in the N-type doping region is greater than the width of the second portion of the fine gate in the P-type doping region.

8. The battery cell according to any one of claims 1 to 6, characterized in that: The cell is a bifacial cell, and the surface of the silicon substrate is the front side and / or the back side.

9. The battery cell according to any one of claims 1 to 7, characterized in that: The first portion of the fine gate has a first surface facing away from the silicon substrate, and the second portion of the fine gate has a second surface facing away from the silicon substrate. Along the thickness direction of the battery cell, the height of the first portion of the fine gate is H1, and the distance between the second surface and the first surface is H2, 0≤H2≤0.5H1.

10. The battery cell according to any one of claims 1 to 7, characterized in that: At the intersection of the trench and the fine gate electrode, the angle between the trench and the fine gate electrode is 70°-115°.

11. The battery cell according to any one of claims 1 to 7, characterized in that: The width of the first portion of fine gates is 5 μm-50 μm; and / or the width of the second portion of fine gates is 6 μm-54 μm.

12. The battery cell according to any one of claims 1 to 7, characterized in that: The cell further includes a connecting portion, which is continuously or discontinuously arranged on the groove, and an extending direction of the connecting portion is perpendicular to the fine gate electrode.

13. The battery cell according to any one of claims 1 to 7, characterized in that: The width of the groove is 15 μm-50 μm; and / or the depth of the groove is 0.1 μm-30 μm.

14. A photovoltaic module, characterized in that: The invention comprises a plurality of battery strings connected in series and / or in parallel, wherein the battery string comprises: an electrical connector and a battery cell according to any one of claims 1 to 13, wherein the electrical connector electrically connects at least two of the battery cells.

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