Battery piece with rivet-type contact points

Abstract

The utility model discloses a battery piece with a riveting type contact point, the battery piece comprises metal grid lines, the metal grid lines comprise a first grid line and a second grid line, the first grid line and the second grid line are provided with an intersection point, the riveting type contact point is arranged at the intersection point of the first grid line and the second grid line, and the riveting type contact point is provided with a riveting type contact point. The riveting type contact point is connected with the first grid line and the second grid line, and the area of the riveting type contact point is larger than that of the junction point. The riveting contact points are arranged at the junction points of the metal grid lines, so that internal stress caused by self-annealing of a continuous structure, metal and the like is eliminated, and the problem of grid separation of the battery is solved. In other words, at the intersections of the metal grid lines, the riveting structures are used for eliminating stress, so that the adhesive force of the grid lines to the battery piece is enhanced, the adhesive force between the grid lines and the battery piece is improved, and the reliability of the battery piece is improved.

Description

Technical Field

[0001] The invention relates to the field of solar energy manufacturing, and in particular to a solar cell with rivet-type contact points. Background Art

[0002] At present, the solar industry produces a large number of crystalline silicon solar cells, and the metal grid lines (electrodes) on their surfaces are made by screen printing silver paste and sintering. However, the electrode grid lines produced by this method have a small aspect ratio. After sintering, the average width of the grid lines is 30-60um, and the height is about 10-15um, which leads to a large shading area of ​​the cell (the front shading area ranges up to 10%-20%). In addition, the price of silver paste is expensive, so how to improve efficiency and reduce production costs is the top priority for each cell manufacturer.

[0003] As low-temperature photovoltaic cells gradually become the leader of future high-efficiency solar cells, traditional silver paste printing and high-temperature sintering are no longer applicable to the production of low-temperature photovoltaic cells. However, there are still some areas for improvement in the low-temperature process: 1. Insufficient adhesion between the metal grid and the cell; 2. Incomplete contact surface, resulting in too high resistance, making Isc, FF and other values ​​too low, and unable to improve the conversion efficiency of the cell. Therefore, whether it is from the perspective of reducing the cost of conductive materials or improving conversion efficiency, these factors make heterojunction cells unfavorable for their promotion and replacement of the current high-temperature photovoltaic cells (such as PERC or TOPCon cells).

[0004] Therefore, the hot topics in recent years all revolve around the method of replacing the traditional low-temperature conductive silver paste metal grid line preparation process with the electroplating metal grid line process, which has become the focus of the development of high-efficiency battery cells in recent years to improve efficiency and reduce costs.

[0005] However, while introducing electroplated metal grid lines to reduce light shielding area and cost, people often overlook the production yield of the cell, which is also one of the factors affecting the overall cost of the cell. That is, the risk of grid lines detaching from the cell may be caused by thinning. Summary of the invention

[0006] In order to overcome the above disadvantages, the purpose of the present invention is to provide a cell with a rivet contact point. The rivet contact point is provided at the intersection of the metal grid line (main grid line or thin grid line). The rivet contact point has the function of stress dispersion and increasing the local contact area, which can improve the bonding force between the overall metal grid line and the cell.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a battery cell with a riveted contact point, including metal grid lines, the metal grid lines include a first grid line and a second grid line, the first grid line and the second grid line have a junction point, a riveted contact point is arranged at the junction point of the first grid line and the second grid line, the riveted contact point connects the first grid line and the second grid line, and the area of the riveted contact point is larger than the area of the junction point. By arranging a riveted contact point at the junction point of the metal grid lines, the internal stress formed due to the self-annealing of the continuous structure and metal is eliminated, and the problem of battery grid detachment is solved. That is, at the intersection of the metal grid lines, a riveted structure is used to eliminate stress, thereby strengthening the adhesion of the grid lines to the battery cell. In this way, the adhesion between the grid lines and the battery cell is improved, and the reliability of the battery cell is enhanced.

[0008] Further, the riveted contact point is circular, and the range of the radius R is 0.707W < R < 20W, where W is the width of the metal grid line. The radius R of the riveted contact point can be of the same consistent size. For example, the radius R of all riveted contact points is equal to 2W. The radius R of the riveted contact point can also be of different sizes. For example, riveted contact points with a radius R = w and riveted contact points with a radius R = 5W are arranged alternately, as long as the radius range of R is within 0.707W < R < 20W.

[0009] Further, if the metal grid lines are designed with different widths, generally referred to as main grid lines and fine grid lines, W is the width of the thick grid line. In this application, the first grid line is the main grid line, the second grid line is the fine grid line, the width of the first grid line is greater than the width of the second grid line, and W is the width of the first grid line.

[0010] Further, the first grid line and the second grid line are perpendicularly arranged, the riveted contact point is diamond-shaped, and the center point of the diamond is the junction point of the first grid line and the second grid line.

[0011] Further, the diamond includes right triangles. The hypotenuse of the right triangle is L, the right sides of the right triangle are arranged along the edges of the first metal grid line and the second metal grid line, and the hypotenuse of the right triangle coincides with the side of the diamond. For example: one right side of the right triangle is arranged along the first metal grid line with a side length of a, and the other right side is arranged along the second metal grid line with a side length of b, then the hypotenuse L of the right triangle = , and the area S of the right triangle = 0.5ab.

[0012] Further, the riveted contact point can be designed in a continuous manner, that is, a riveted contact point is arranged at each overlapping junction of the grid lines; or it can be designed in a non - continuous manner. For example, a riveted contact point is arranged every three grid lines.

[0013] The beneficial effect of the present invention is that by setting a rivet contact point at the intersection of the metal grid lines, the internal stress formed by the continuous structure and the self-annealing of the metal is eliminated, and the problem of battery grid detachment is solved. That is, at the intersection of the metal grid lines, the rivet structure is used to eliminate the stress, thereby strengthening the adhesion of the grid lines to the battery cells, thus improving the adhesion between the grid lines and the battery cells and improving the reliability of the battery cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 A top view of a battery cell with rivet-type contact points according to an embodiment of the present invention;

[0017] Figure 2 A top view of a circular rivet-shaped contact point according to an embodiment of the present invention;

[0018] Figure 3 FIG. 1 is a top view of a diamond-shaped rivet contact point according to an embodiment of the present invention.

[0019] Among them: 1. First grid line; 2. Second grid line; 3. Riveted contact point. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0021] The applicant found that the hot topics in recent years all revolve around the method of replacing the traditional low-temperature conductive silver paste metal grid line preparation process with the electroplated metal grid line process, which has become the focus of the development of high-efficiency solar cells in recent years to improve efficiency and reduce costs. However, while introducing electroplated metal grid lines to reduce light shielding area and reduce costs, people often ignore the production yield of solar cells, which is also one of the costs of the overall solar cells. That is, the thinning of the lines may cause the risk of the grid lines detaching from the solar cells.

[0022] An embodiment of the present invention provides a solar cell with rivet-shaped contact points, including metal grid lines. The metal grid lines include a first grid line 11 and a second grid line 2. The first grid line 1 and the second grid line 2 have a junction point, and a rivet-shaped contact point 3 is arranged at the junction point of the first grid line 1 and the second grid line 2. The rivet-shaped contact point 3 connects the first grid line 1 and the second grid line 2.

[0023] Further, the rivet-shaped contact point 3 is circular, and the range of the radius R is 0.707W < R < 20W, where W is the width of the metal grid line.

[0024] Further, the width of the first grid line 1 is greater than the width of the second grid line 2, and W is the width of the first grid line 1.

[0025] Further, the first grid line 1 and the second grid line 2 are perpendicularly arranged, the rivet-shaped contact point 3 is diamond-shaped, and the center point of the diamond is the junction point of the first grid line 1 and the second grid line 2.

[0026] Further, the diamond-shaped rivet-shaped contact point 3 includes a right triangle. The two right sides of the right triangle are respectively arranged along the edges of the first metal grid line and the second metal grid line, and the hypotenuse of the right triangle coincides with the side of the diamond.

[0027] Embodiment

[0028] The following embodiments more specifically describe the content disclosed in the present invention. These embodiments are only for illustrative purposes, because various modifications and changes within the scope of the present invention are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and all instruments used in the embodiments are commercially available.

[0029] Embodiment 1

[0030] S1. ITO conductive layers are prepared on both surfaces of the solar cell.

[0031] S2. The above-treated solar cell is covered with a dry mask (commonly known as dry film) by means of imprinting. The thickness of the dry film is ~40um. The process description of imprinting the dry film is as follows: The solar cell is pre-heated to 50 degrees Celsius, and then the dry film is pressed on the solar cell. The bonding pressure is 2 Kg / cm 2 , and the lamination time is 4 seconds.

[0032] S3. After the dry film is pressed, the exposure process is immediately carried out to transfer the rivet contact metal grid line pattern to the dry film. The exposure process operating conditions are to use a direct writing exposure machine for exposure. The exposure intensity conditions are 220mj / cm^2 and the exposure wavelength is 405nm. See the attached Figure 1 and attached Figure 2 As shown, the design of the rivet-type contact metal grid line pattern is to prepare a circular rivet-type contact metal grid line pattern with a radius of 2 times the grid line width, with the center of each grid line intersection as the origin. This embodiment has only one grid line width design, and its line width is 20um, so a circular rivet-type contact metal grid line pattern with a radius of 40um is obtained.

[0033] The above-mentioned cell is sent to the developer for development process. The operating conditions are sodium bicarbonate with a ratio concentration of 3%. The process operating conditions are: the development temperature is 50°C, the time is 180 seconds and the spraying pressure is 2.5Kg / cm^2. The metal grid line area is left open for the subsequent rivet contact point metal grid line layer process.

[0034] S4. Design the above-mentioned battery cell with a rivet-type contact point pattern, and use an electrolytic reduction process to prepare a double-sided rivet-type contact point metal grid line layer deposition.

[0035] S5, remove the mask layer to prepare a cell with rivet-type contact points. In the film removal process, use 8% sodium hydroxide, 35°C, 300 seconds and 2.5Kg / cm^2 of spraying pressure to remove and clean the dry film layer, and then obtain a cell with a rivet-type contact point metal grid structure.

[0036] Example 2

[0037] S1, ITO conductive layers are prepared on both sides of the cell.

[0038] S2, the processed cell is covered with a dry mask (commonly known as dry film) by embossing. The thickness of the dry film is ~40um. The process of embossing the dry film is as follows: Preheat the cell to 50 degrees Celsius, and then press the dry film on the cell. The lamination pressure is 2Kg / cm 2 , pressing time 4 seconds.

[0039] S3, after the dry film is pressed, the exposure process is immediately carried out to transfer the rivet contact metal grid line pattern to the dry film. The exposure process operation condition is to expose with a direct writing exposure machine. The exposure intensity condition is 220mj / cm 2 , the exposure wavelength is 405nm. Figure 3As shown, the design of the rivet contact metal grid line pattern is a rhombus prepared with the center of each grid line as the origin, and the rhombus is formed by a right triangle, the hypotenuse of the right triangle is L, and the right angle of the right triangle is set along the edge of the first metal grid line and the second metal grid line. One right angle of the right triangle is set along the first metal grid line, and the side length is a = 30μm, and the other right angle is set along the second metal grid line, and the side length is b = 40μm, then the hypotenuse L of the right triangle is =50μm.

[0040] The above-mentioned cell is sent to the developer for development process. The operating conditions are sodium bicarbonate with a ratio concentration of 3%. The process operating conditions are: the development temperature is 50°C, the time is 180 seconds and the spraying pressure is 2.5Kg / cm^2. The metal grid line area is left open for the subsequent rivet contact point metal grid line layer process.

[0041] S4. Design the above-mentioned battery cell with a rivet-type contact point pattern, and use an electrolytic reduction process to prepare a double-sided rivet-type contact point metal grid line layer deposition.

[0042] S5, remove the mask layer to prepare a battery cell with rivet-type contact points. In the mask removal process, use 8% sodium hydroxide, 35°C, 300 seconds and a spraying pressure of 2.5Kg / cm 2 After the dry film layer is removed and cleaned, a battery cell with a rivet-type contact point metal grid line structure is obtained.

[0043] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A cell with rivet-type contact points, comprising metal grid lines, wherein the metal grid lines include a first grid line and a second grid line, wherein the first grid line and the second grid line have an intersection point, wherein: A rivet - type contact point is provided at the intersection of the first gate line and the second gate line, and the rivet - type contact point connects the first gate line and the second gate line.

2. The battery cell with rivet-type contact points according to claim 1, characterized in that: The rivet - type contact point is circular, and the range of the radius R of the rivet - type contact point is 0.707W < R < 20W, where W is the width of the metal gate line.

3. The battery cell with rivet-type contact points according to claim 2, characterized in that: The width of the first gate line is greater than the width of the second gate line, and W is the width of the first gate line.

4. The battery cell with rivet-type contact points according to claim 1, characterized in that: The first gate line and the second gate line are perpendicularly arranged, the rivet - type contact point is diamond - shaped, and the center point of the diamond is the intersection of the first gate line and the second gate line.

5. The battery cell with rivet-type contact points according to claim 4, characterized in that: The diamond - shaped rivet - type contact point includes a right - angled triangle. The two right - angled sides of the right - angled triangle are respectively arranged along the edges of the first metal gate line and the second metal gate line, and the hypotenuse of the right - angled triangle coincides with the side of the diamond.

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