Laminated battery piece and preparation method thereof, battery string, printing screen plate and photovoltaic module

Abstract

The invention relates to the technical field of photovoltaic cells, in particular to a laminated cell and a preparation method thereof, a printing screen plate and a photovoltaic module, and aims to solve the problem that free series welding between modules cannot be realized by an existing three-end laminated cell. Therefore, the invention provides the laminated battery piece, the front surface of the laminated battery piece is provided with at least one front surface grid line, the front surface grid line is provided with at least one front surface electrode welding spot, the back surface of the laminated battery piece comprises a first grid line and a second grid line, and the first grid line and the second grid line are arranged along a second direction perpendicular to the first direction; the first grid line is provided with at least one first electrode welding spot, the second grid line is provided with at least one second electrode welding spot with opposite polarity, the first grid line is also provided with at least one third electrode welding spot with opposite polarity to the front electrode welding spot, and the projections of the first electrode welding spot, the second electrode welding spot and the third electrode welding spot in the second direction are not overlapped. According to the laminated battery piece provided by the invention, the problem that a plurality of three-terminal battery pieces cannot be freely assembled is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic cells, and in particular to a laminated cell sheet and a preparation method thereof, a cell string, a printing screen, and a photovoltaic module. Background Art

[0002] With the continuous advancement of photovoltaic technology, the efficiency of single-crystal silicon cells is approaching its theoretical upper limit. To further improve the energy conversion efficiency of photovoltaic cells and overcome the thermal relaxation losses of single-junction cells, the concept of multi-junction cells has been proposed. Currently, a two-junction tandem cell, formed by stacking a wide-bandgap perovskite cell on a crystalline silicon cell, has achieved an energy conversion efficiency of 34.6%, far exceeding the current single-crystal silicon cell (27.3%), demonstrating the superior performance advantages of multi-junction cells. As the number of junctions increases, the theoretical efficiency will continue to rise. Two-junction tandem cells are currently divided into two-terminal tandem cells (with only two electrodes, positive and negative), three-terminal tandem cells (with three electrodes, positive, middle, and negative), and four-terminal tandem cells (with two pairs of independent positive and negative electrodes). While two-terminal tandem cells have high front-side efficiency, they cannot effectively utilize photons incident from the back side, resulting in a very low bifaciality. Four-terminal tandem cells, in which the two cells are connected by an optical adhesive film, suffer from high optical losses, limiting further efficiency improvements. Three-terminal tandem cells, however, offer high bifaciality and low optical losses, making them a promising tandem technology. However, the production of components for three-terminal stacked batteries is extremely difficult.

[0003] Specifically, if Figure 1 and Figure 2 As shown in , when forming an assembly of an existing three-terminal back-contact stacked battery, adjacent battery cells need to be serially welded, such as the first battery cell 1′ and the second battery cell 2′ are serially welded, and the second battery cell 2′ and the third battery cell 3′ are serially welded. The first battery cell 1′ includes a first bottom battery 11′ and a first top battery 12′, the second battery cell 2′ includes a second bottom battery 21′ and a second top battery 22′, and the third battery cell 3′ includes a third bottom battery 31′ and a third top battery 32′. Taking the first battery cell 1′ as an example, the front of the first top battery 12′ is provided with a front grid line 13′ and a front welding point (not shown) to form the front electrode of the top battery; the back of the first bottom battery 11′ is provided with a back grid line 14′ and a back welding point (not shown) to form the back electrode of the bottom battery. The polarity of the front electrodes of the first cell 1′, the second cell 2′, and the third cell 3′ is the same, and the back electrodes of the first cell 1′ and the third cell 3′ are the same and correspond to the back electrode of the second cell 2′. For example, in a perovskite-BC stacked cell, the front electrodes of the perovskite top cell are all negative electrodes.

[0004] like Figure 2As shown in the figure, the back electrode of the first cell 1' is an electrode structure with positive and negative electrodes arranged repeatedly. Correspondingly, the back electrode of the second cell 2' is an electrode structure with negative and positive electrodes arranged repeatedly. In this way, the positive electrode in the back electrode of the first cell 1' can be in a straight line with the negative electrode in the back electrode of the second cell 2', so that they can be connected through welding with a welding ribbon. In addition, the front electrode of the second cell 2' also needs to be connected to the positive electrode in the back electrode of the first cell 1' by a welding ribbon in a Z-shaped welding manner. The Z-shaped welding ribbon is as shown in FIG. Figure 2 However, when the number of cells needs to be increased in order to obtain a higher open circuit voltage, such as when a third cell 3' (with the same structure as the first cell 1') is connected in series, since the back electrode of the second cell 2' needs to be through-welded to the back electrode of the third cell 3', the electrode arrangement of the back electrode of the third cell 3' is the same as that of the back electrode of the first cell 1', which is a positive-negative and positive-negative repeated electrode structure, and the front electrode is the same as the front electrode of the first cell 1' and the second cell 2', both of which are negative electrodes. At this time, although the back electrodes of the second cell 2' and the third cell 3' can be through-welded, Since the back electrode of the second battery cell 2′ is an electrode structure with negative and positive electrodes repeatedly arranged, the back electrode corresponding to the front electrode of the third battery cell 3′ is a negative electrode, which has the same polarity as the front electrode of the third battery cell 3′. Therefore, under the premise of satisfying the back electrode through welding, the second battery cell 2′ and the third battery cell 3′ cannot be welded by Z-shaped welding (because the front electrode of the third battery cell 3′ and the corresponding back electrode of the second battery cell 2′ are both negative electrodes and cannot be welded in series by welding ribbons). Therefore, when the number of battery cells increases, continuous series welding cannot be achieved, which greatly limits the open circuit voltage and overall output power of the three-terminal stacked battery. Summary of the Invention

[0005] The present invention aims to solve the above technical problem, that is, to solve the problem that the existing three-terminal stacked battery cells cannot achieve free series welding between components.

[0006] To this end, the present invention provides a laminated solar cell, wherein the front side of the solar cell is provided with at least one front grid line, and at least one front electrode welding point is provided on the at least one front grid line.

[0007] The back side of the battery cell includes:

[0008] At least one first gate line and at least one second gate line extending along a first direction, wherein the first gate line and the second gate line are arranged at intervals along a second direction perpendicular to the first direction;

[0009] The first gate line is provided with at least one first electrode pad, and the second gate line is provided with at least one second electrode pad, wherein the polarity of the first electrode pad is opposite to that of the second electrode pad;

[0010] Among them, at least one of the first gate lines is also provided with at least one third electrode solder joint, the polarity of the third electrode solder joint is opposite to the polarity of the front electrode solder joint, and the projections of the first electrode solder joint, the second electrode solder joint and the third electrode solder joint in the second direction do not overlap.

[0011] In some feasible implementations of the above-mentioned laminated solar cell, in the first direction, the first grid line and the second grid line extend continuously.

[0012] In some feasible embodiments of the above-mentioned laminated battery cell, in the second direction, the plurality of the front electrode welding spots are linearly arranged to form a front welding spot row, and the plurality of the third electrode welding spots are linearly arranged to form a third welding spot row;

[0013] In the first direction, there is at least one front solder joint row and at least one third solder joint row.

[0014] In a third direction perpendicular to both the first direction and the second direction, the projections of at least one of the front solder joint rows and at least one of the third solder joint rows do not overlap, and a minimum spacing L between the projections of the two in the first direction is greater than 0.01 mm and less than 1 mm; or

[0015] In a third direction perpendicular to both the first direction and the second direction, a projection of at least one of the front welding spot rows at least partially overlaps with a projection of at least one of the third welding spot rows.

[0016] In some feasible implementations of the above-mentioned stacked battery cell, the number of the front welding point rows is the same as the number of the third welding point rows.

[0017] In some feasible embodiments of the above-mentioned stacked battery cell, in the second direction, an insulating glue point is provided on the first grid line at a position corresponding to the second electrode welding point, and an insulating glue point is provided on the second grid line at a position corresponding to the first electrode welding point and the third electrode welding point.

[0018] In some feasible embodiments of the above-mentioned stacked battery cell, in the second direction, a plurality of the first electrode welding points are linearly arranged to form a first welding point row, a plurality of the second electrode welding points are linearly arranged to form a second welding point row, and at least one first welding point row and one second welding point row are adjacently arranged in the first direction to form an electrode pair.

[0019] In some feasible embodiments of the above-mentioned stacked battery cell, the first welding point row and the second welding point row are alternately arranged in the first direction to form a plurality of electrode pairs, and at least one electrode pair of the plurality of electrode pairs is configured with one third electrode welding point row.

[0020] In some feasible implementations of the above-mentioned stacked battery cell, the first welding point row, the second welding point row, and the third welding point row are arranged in an array in the first direction.

[0021] In some feasible embodiments of the above-mentioned stacked cell, the stacked cell is a perovskite-crystalline silicon stacked cell, or a cadmium telluride-crystalline silicon stacked cell, or a copper indium gallium selenide-crystalline silicon stacked cell, or a copper zinc tin sulfur-crystalline silicon stacked cell.

[0022] In some feasible embodiments of the above-mentioned laminated cell sheet, the laminated cell sheet comprises at least a top cell and a bottom cell stacked in layers, the bottom cell being a back contact cell; and / or

[0023] The stacked battery cell is a three-terminal stacked battery cell.

[0024] In a second aspect, the present invention further provides a battery string comprising the laminated battery cells described in any one of the aforementioned technical solutions.

[0025] In a third aspect, the present invention further provides a photovoltaic module, comprising the battery string described in any one of the aforementioned technical solutions.

[0026] In some feasible embodiments of the above-mentioned photovoltaic components, in the second direction, multiple first electrode welding points of the stacked battery cells are linearly arranged to form a first welding point row, multiple second electrode welding points are linearly arranged to form a second welding point row, multiple third electrode welding points are arranged to form a third welding point row, and multiple front electrode welding points are arranged to form a front welding point row. The battery string also includes a first welding strip, a second welding strip and a third welding strip extending along the second direction. The first welding strip is used to connect the first welding point row on the back of one battery cell with the second welding point row on the back of the other battery cell of two adjacent battery cells. The second welding strip is used to connect the second welding point row on the back of the one battery cell with the first welding point row on the back of the other battery cell. The third welding strip is used to connect the front welding point row of the one battery cell with the third welding point row on the back of the other battery cell.

[0027] In a fourth aspect, the present invention further provides a printing screen, comprising a screen substrate, the screen substrate being provided with at least one first grid line pattern and at least one second grid line pattern extending along a first direction, the first grid line pattern and the second grid line pattern being arranged at intervals along a second direction perpendicular to the first direction;

[0028] The screen substrate is also provided with at least one first welding point pattern, at least one second welding point pattern, and at least one third welding point pattern. In the third direction, the projections of the first welding point pattern and the third welding point pattern fall on the projection of the first grid line pattern, and the projection of the second welding point pattern falls on the projection of the second grid line pattern. The projections of the first welding point pattern, the second welding point pattern and the third welding point pattern in the second direction do not overlap, and the third direction is perpendicular to the first direction and the second direction.

[0029] In some feasible embodiments of the above-mentioned printing screen, the screen substrate includes an adaptive first screen substrate and a second screen substrate, the first grid line pattern and the second grid line pattern are arranged on the first screen substrate, and the first welding point pattern, the second welding point pattern and the third welding point pattern are arranged on the second screen substrate.

[0030] In some feasible implementations of the above-mentioned printing screen, the first grid line pattern and the second grid line pattern extend continuously in the first direction.

[0031] In some feasible embodiments of the above-mentioned printing screen, in the second direction, multiple first welding point patterns are linearly arranged to form a first pattern row, multiple second welding point patterns are linearly arranged to form a second pattern row, and multiple third welding point patterns are linearly arranged to form a third pattern row, and at least one first pattern row and one second pattern row are adjacent to each other in the first direction.

[0032] In some feasible implementations of the above-mentioned printing screen, the first pattern rows and the second pattern rows are alternately arranged in the first direction.

[0033] In some feasible implementations of the above-mentioned printing screen, the first pattern row, the second pattern row, and the third pattern row are arranged in an array in the first direction.

[0034] In some feasible embodiments of the above-mentioned printing screen, the printing screen is used to prepare the back electrode of the bottom cell of the laminated cell, and the bottom cell of the laminated cell is a back contact cell; and / or

[0035] The stacked battery cell is a three-terminal stacked battery cell.

[0036] In a fifth aspect, the present invention further provides a method for preparing a laminated battery cell, wherein the battery cell is prepared using the printing screen described in any of the aforementioned technical solutions, and the battery cell is the laminated battery cell described in any of the aforementioned technical solutions.

[0037] The laminated battery cell provided by the present invention has the following beneficial effects:

[0038] The laminated battery cell provided by the present invention adds an electrode welding point dedicated to connecting to the front electrode of the adjacent battery cell, i.e., a third electrode welding point, to the bottom battery of the traditional three-terminal laminated battery cell. In this way, during the process of component series welding, there is no need to consider the polarity of the original back electrodes of each bottom battery cell. The original back electrodes can be through-welded through the welding ribbon, and the front electrodes can be directly welded to the dedicated third electrode welding point. This solves the problem that the component ends cannot be welded in series, realizes the free series connection of multiple battery cells, and thus removes the limitation of open circuit voltage. The original back electrodes of adjacent battery cells only need to ensure that the positive and negative connections meet the through-welding path consistency, and do not need to form a strong association with the position and polarity of the front electrode, so that the through-welding of the back electrodes is no longer constrained by the polarity of the front electrode. In addition, the front electrode is connected through the dedicated third welding point, which can reduce the alignment error and the risk of cold welding.

[0039] The printing screen, the method for preparing the laminated cell and the photovoltaic module provided by the present invention can produce the laminated cell in any of the aforementioned technical solutions, and therefore have or can bring about all the technical effects of the aforementioned laminated cell, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:

[0041] Figure 1 A schematic diagram of the structure of a three-terminal stacked cell before forming a module in the prior art, showing the arrangement of the top and bottom grid lines of each cell, as well as the corresponding polarity of the grid lines;

[0042] Figure 2 for Figure 1 The corresponding three-dimensional diagram shows the series welding of the back electrodes of the first and second battery cells, as well as the schematic structure of the Z-shaped welding of the front and back electrodes, and illustrates the principle that the second and third battery cells cannot be series welded;

[0043] Figure 3 A schematic structural diagram of the front electrode of a first battery cell provided in an embodiment of the present invention;

[0044] Figure 4 A schematic structural diagram of the back electrode of a first cell provided by an embodiment of the present invention;

[0045] Figure 5 A schematic structural diagram of the back electrode of the second cell provided by an embodiment of the present invention;

[0046] Figure 6A schematic structural diagram of the back electrodes of the first battery cell and the second battery cell provided in an embodiment of the present invention after being serially welded;

[0047] Figure 7 A schematic diagram of the structure of a first battery cell and a second battery cell after being serially welded according to an embodiment of the present invention;

[0048] Figure 8 A schematic structural diagram of the front electrodes and back electrodes of the first, second, and third battery cells provided in an embodiment of the present invention after Z-shaped welding;

[0049] Figure 9 Another embodiment of the back electrode of the first cell provided in the embodiment of the present invention;

[0050] Figure 10 A schematic diagram showing that the projections of the front solder joint row and the third solder joint row in the third direction do not overlap, provided by an embodiment of the present invention;

[0051] Figure 11 A first printing screen for preparing a back electrode of a first battery cell provided in an embodiment of the present invention;

[0052] Figure 12 A second printing screen for preparing the back electrode of a second battery cell provided in an embodiment of the present invention;

[0053] Figure 13 A third printing screen for preparing the back electrode of the first battery cell provided by another embodiment of the present invention;

[0054] Figure 14 A fourth printing screen for preparing the back electrode of the first battery cell provided by another embodiment of the present invention;

[0055] Figure 15 A fifth printing screen for preparing a back electrode of a second battery cell provided by another embodiment of the present invention;

[0056] Figure 16 Schematic diagram of the structure of a triple-junction stacked cell applicable to the present invention.

[0057] List of reference numerals:

[0058] 1′, first cell; 11′, first bottom cell; 12′, first top cell; 13′, front busbar; 14′, back busbar; 2′, second cell; 21′, second bottom cell; 22′, second top cell; 3′, third cell; 31′, third bottom cell; 32′, third top cell;

[0059] 1. First cell; 11. First bottom cell; 111. First busbar; 112. Second busbar; 113. First electrode solder joint; 1131. First solder joint row; 114. Second electrode solder joint; 1141. Second solder joint row; 115. Insulation glue point; 116. Third electrode solder joint; 1161. Third solder joint row; 12. First top cell; 121. Front busbar; 122. Front electrode solder joint; 1221. Front solder joint row; 2. Second cell; 2 1. Second bottom cell; 211. First busbar; 212. Second busbar; 213. First electrode solder joint; 2131. First solder joint row; 214. Second electrode solder joint; 2141. Second solder joint row; 215. Insulating adhesive; 216. Third electrode solder joint; 2161. Third solder joint row; 22. Second top cell; 221. Front busbar; 222. Front electrode solder joint; 3. Third cell; 4. First solder strip; 5. Second solder strip; 6. Third solder strip.

[0060] 71, first printing screen; 711, first grid line pattern; 712, second grid line pattern; 713, first solder joint pattern; 714, second solder joint pattern; 715, third solder joint pattern;

[0061] 72, second printing screen; 721, first grid line pattern; 722, second grid line pattern; 723, first solder joint pattern; 724, second solder joint pattern; 725, third solder joint pattern;

[0062] 73, third printing screen; 731, first grid line pattern; 732, second grid line pattern;

[0063] 74, fourth printing screen; 741, first solder joint pattern; 7411, first pattern row; 742, second solder joint pattern; 7421, second pattern row; 743, third solder joint pattern; 7431, third pattern row;

[0064] 75. Fifth printing screen; 751. First solder joint pattern; 752. Second solder joint pattern; 753. Third solder joint pattern. DETAILED DESCRIPTION

[0065] Preferred embodiments of the present invention are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are intended only to illustrate the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art may adjust these embodiments as needed to suit specific applications.

[0066] In order to better illustrate the present invention, numerous specific details are given in the following detailed description. It should be understood by those skilled in the art that the present invention can also be implemented without certain specific details.

[0067] In the description of the present invention, terms such as "upper," "lower," "inner," "outer," "front," and "back" indicating directions or positional relationships are based on the directions or positional relationships shown in the figures. This is for ease of description only and does not indicate or imply that the device to be protected must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, the orientations described in the following embodiments should not be construed as limitations on the present invention. Furthermore, ordinal numbers such as "first" and "second" are used for convenience only and are not intended to indicate or imply relative importance.

[0068] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted" and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; and direct or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0069] The following are some of the terms involved in the present invention:

[0070] The two-junction tandem cell is composed of a top cell and a bottom cell connected by an intermediate transparent conductive layer to form a vertical stacking structure. The top cell usually uses a wide bandgap material to absorb short-wavelength high-energy photons, while the bottom cell uses a narrow bandgap material to absorb long-wavelength low-energy photons. For example, the perovskite-crystalline silicon tandem cell is a common two-junction tandem cell. It forms a series structure of a wide-bandgap perovskite top cell and a narrow-bandgap crystalline silicon bottom cell by vertically stacking the perovskite cell and the crystalline silicon cell. It utilizes the efficient absorption of short-wavelength light by perovskite and the deep utilization of long-wavelength light by crystalline silicon to achieve spectral complementarity and energy ladder conversion. The core advantage of the perovskite-crystalline silicon tandem cell is that it breaks through the efficiency limit of single-crystal silicon cells, combining the dual advantages of the low-cost solution preparation process of perovskite and the mature industrial chain of crystalline silicon. At the same time, the stacking design reduces hot carrier recombination losses and significantly improves the photoelectric conversion efficiency.

[0071] A triple-junction tandem cell consists of a top cell, a middle cell, and a bottom cell connected by an intermediate transparent conductive layer to form a vertical stacked structure. Similar to a two-junction tandem cell, a triple-junction tandem cell only adds an intermediate cell. The top cell usually uses a wide bandgap material to absorb short-wavelength, high-energy photons, the middle cell usually uses an intermediate bandgap material to absorb medium-wavelength, high-energy photons, and the bottom cell uses a narrow bandgap material to absorb long-wavelength, low-energy photons. For example, a double perovskite-crystalline silicon tandem cell is a common triple-junction tandem cell. By vertically stacking a perovskite cell and a crystalline silicon cell, it forms a series structure of a wide-bandgap perovskite top cell, a medium-bandgap perovskite middle cell, and a narrow-bandgap crystalline silicon bottom cell. This structure utilizes the efficient absorption of short- and medium-wavelength light by perovskites and the deep utilization of long-wavelength light by crystalline silicon to achieve spectral complementarity and energy ladder conversion.

[0072] A multi-junction stacked cell refers to a vertically stacked structure formed by multiple cells connected by an intermediate transparent conductive layer, and the number of stacked cell layers is equal to the number of junctions.

[0073] The top cell refers to the cell at the top of a multi-junction stacked cell, and the bottom cell refers to the cell at the bottom of a multi-junction stacked cell. The number of junctions in a stacked cell can be two, three, or four. It should be noted that if the stacked cell is a multi-junction stacked cell (three or more junctions), the multi-junction stacked cell includes at least a top cell and a bottom cell stacked together. In other words, regardless of the number of junctions in the stacked cell, it includes at least a top cell and a bottom cell. If the number of junctions is three or more, in addition to the top cell and the bottom cell, it also includes at least one intermediate cell stacked between the top cell and the bottom cell.

[0074] A three-terminal structure refers to a two-junction stacked battery in which the top and bottom cells each have an independent electrode and share a middle electrode, enabling independent extraction of the top and bottom cell currents. This structure allows each sub-cell to operate electrically independently, avoiding the efficiency loss caused by current mismatch in traditional two-terminal series structures. For example, when the top cell experiences a localized current drop due to shading or material defects, the bottom cell can still maintain its normal operating current. By extracting electrical energy from the sub-cells through independent circuits, the system can significantly improve overall power generation stability.

[0075] A soldering point refers to a specific location on a grid line for connecting a soldering strip. A positive soldering point refers to a soldering point connected to a positive grid line, and a negative soldering point refers to a soldering point connected to a negative grid line.

[0076] The embodiment of the present invention is illustrated by taking a perovskite-crystalline silicon tandem cell as an example, wherein the crystalline silicon subcell adopts a back contact design, and is therefore also called a BC (Back Contact) cell, which includes two metal electrodes: an N-type contact electrode (i.e., a negative electrode) connected to the N-type region of the crystalline silicon bottom to collect electrons; and a P-type contact electrode (i.e., a positive electrode) connected to the P-type region of the crystalline silicon bottom to collect holes. By designing all the positive and negative electrodes of the battery on the back of the battery (rather than the traditional front and back), the BC battery eliminates the obstruction of the metal grid lines on the front, thereby maximizing the use of incident light and improving conversion efficiency. Therefore, the perovskite-crystalline silicon tandem cell provided in the embodiment of the present invention can also be called a perovskite-BC tandem cell.

[0077] The back structure of the bottom cell of the perovskite-BC three-terminal stacked cell used to form a component in series in the prior art is as follows: Figure 1 As shown in FIG, the back grid lines include alternating positive grid lines (with Figure 1 The negative grid lines (extending perpendicular to the paper) and the negative grid lines ( Figure 1The positive electrode grid line is provided with a positive electrode welding point (not shown), and the negative electrode grid line is provided with a negative electrode welding point (not shown). The positive electrode welding points on all the positive electrode grid lines that are located on the same straight line (perpendicular to the direction of the positive electrode grid line) can be connected by a welding strip (which can be called a positive electrode welding strip) to form the positive electrode of the bottom battery; similarly, the negative electrode welding points on all the negative electrode grid lines that are located on the same straight line (perpendicular to the direction of the negative electrode grid line) are connected by a welding strip (which can be called a negative electrode welding strip) to form the negative electrode of the bottom battery. The arrangement of the welding strips for connecting the positive electrode welding points and the welding strips for connecting the negative electrode welding points is as follows: Figure 2 As shown in the figure, the soldering ribbons are also arranged in an alternating positive-negative pattern, with the direction of the soldering ribbon extending perpendicular to the direction of the grid lines. However, when there are three or more cells connected in series, the front electrode of the top cell cannot be soldered to the back electrode of the adjacent bottom cell.

[0078] In order to solve the problem that existing three-terminal stacked batteries cannot be freely soldered in series when forming an assembly, an embodiment of the present invention provides a stacked battery cell. By adding welding points dedicated to connecting with the metal electrodes of the top battery on the metal grid lines of the back-contact bottom battery, the back electrodes mixed in the existing three-terminal stacked batteries are functionally separated, and the electrode restrictions in the soldering process are removed, thereby solving the problem that free soldering cannot be performed in the assembly process.

[0079] The present invention provides a perovskite-crystalline silicon stacked cell, and a photovoltaic module formed by serially soldering multiple (greater than or equal to three) perovskite-crystalline silicon stacked cells. Specifically, the following embodiments provide two back structures of the cell, as well as an example of three perovskite-crystalline silicon stacked cells connected in series. For ease of description and understanding, the three cells in series are defined as a first cell, a second cell, and a third cell, respectively. The structures of the first cell and the third cell are identical, so this solution is essentially a series connection of multiple first cells and multiple second cells.

[0080] The following combination Figures 3 to 8 The structure of the perovskite-crystalline silicon tandem cell provided by the present invention is described.

[0081] like Figure 3 As shown in FIG, which shows the front structure of each battery cell, Figure 3 The structure corresponds to Figure 7The first top battery 12 of the first battery cell 1, and the second top battery of the second battery cell 2. Taking the first battery cell 1 as an example, the front of the first battery cell 1 is provided with at least one front grid line. In this embodiment, a plurality of front grid lines 121 are provided on the front of the first battery cell 1 as an example. At least one front electrode welding point 122 is provided on at least one front grid line 121. In this embodiment, at least one front electrode welding point 122 is provided on each front grid line 121 as an example. The position of the front electrode welding point 122 needs to ensure that it is linearly arranged (on a straight line) in the second direction (the column direction in the figure) to form a front welding point row 1221, so that the corresponding front electrode welding point can be covered by the welding tape after the welding tape is laid. In the first direction, the number of the front welding point row 1221 is at least one. Figure 3 An example of three front electrode solder joints 122 being provided on each front grid line 121 is shown in the figure. In the first direction (row direction in the figure), there are three front solder joint rows 1221 formed. It will be understood that the number of front electrode solder joints 122 on each front grid line 121 in the above example is merely exemplary, and may also be other values, such as some front grid lines not being provided with front electrode solder joints, or being provided with 1, 2, 4, 5, etc. The polarity of the front electrode solder joint 122 is the same as that of the front grid line 121, and the polarity of the front grid line 121 may be either positive or negative. Taking the perovskite-crystalline silicon laminated cell as an example, the polarity of the front grid line 121 depends on the perovskite structure (PIN or NIP), and is usually negative (NIP).

[0082] like Figure 4 、 Figure 5 and Figure 7 As shown, Figure 4 and Figure 5 Two back structures of perovskite-crystalline silicon stacked cells used to form a battery string in series are shown, wherein: Figure 4 The structural correspondence Figure 7 The back structure of the first bottom cell 11 of the first cell 1, Figure 5 The structural correspondence Figure 7 The back structure of the second bottom battery of the second battery cell 2.

[0083] Specifically, if Figure 4 As shown in , the back side of the first battery cell 1 includes at least one first gate line and at least one second gate line extending along a first direction (row direction in the figure). In this embodiment, a plurality of first gate lines 111 and a plurality of second gate lines 112 are taken as an example. Preferably, the first gate lines 111 and the second gate lines 112 in this embodiment extend continuously in the first direction. The first gate lines 111 and the second gate lines 112 are arranged at intervals along a second direction (column direction in the figure) perpendicular to the first direction (row direction in the figure). As shown in Figure 5As shown in the figure, the back side of the second battery cell 2 includes a plurality of first gate lines 211 and second gate lines 212 extending along a first direction (row direction in the figure), and the first gate lines 211 and second gate lines 212 are arranged at intervals along a second direction (column direction in the figure) perpendicular to the first direction (row direction in the figure).

[0084] It should be noted that the number relationship between the first gate lines and the second gate lines can be equal or an odd-even relationship.

[0085] In the first solar cell 1, the first gate line 111 is provided with at least one first electrode solder joint 113, and the second gate line 112 is provided with at least one second electrode solder joint 114. In this embodiment, a case where the first gate line 111 is provided with multiple first electrode solder joints 113 and the second gate line 112 is provided with multiple second electrode solder joints 114 is taken as an example. The polarity of the first electrode solder joint 113 is consistent with the polarity of the first gate line 111, and the polarity of the second electrode solder joint 114 is consistent with the polarity of the second gate line 112. Therefore, the polarity of the first electrode solder joint 113 and the second electrode solder joint 114 on the first solar cell 1 are opposite.

[0086] In this embodiment, on the second battery cell 2, the first gate line 211 is provided with multiple first electrode welding points 213, and the second gate line 212 is provided with multiple second electrode welding points 214. The polarity of the first electrode welding points 213 is consistent with the polarity of the first gate line 211, and the polarity of the second electrode welding points 214 is consistent with the polarity of the second gate line 212. Therefore, the polarity of the first electrode welding points 213 and the second electrode welding points 214 on the second battery cell 2 are opposite.

[0087] The difference between the first battery cell 1 and the second battery cell 2 is that the arrangement positions of the first electrode welding points and the second electrode welding points are different in the first direction (row direction in the figure). Figure 4 and Figure 5 In the second direction (the column direction in the figure), the first welding point row 113 formed by the linear arrangement of the first electrode welding points 113 of the first battery cell 1 corresponds to the second welding point row 214 formed by the linear arrangement of the second electrode welding points 214 of the second battery cell 2 (they can be completely on a straight line or slightly staggered, as long as they can be welded with the welding ribbon), and the second welding point row 1141 formed by the linear arrangement of the second electrode welding points 114 of the first battery cell 1 corresponds to the first welding point row 2131 formed by the linear arrangement of the first electrode welding points 213 of the second battery cell 2.

[0088] In the second direction (column direction in the figure), the column where the first electrode welding point 113 (positive pole) of the first battery cell 1 is located is in the same column as the column where the second electrode welding point 214 (negative pole) of the second battery cell 2 is located, and through welding can be achieved through the first welding ribbon 4 without the welding ribbon forming a bend, that is, the first welding ribbon 4 extends along the second direction. Correspondingly, the column where the second electrode welding point 114 (negative pole) of the first battery cell 1 is located is in the same column as the column where the first electrode welding point 213 (positive pole) of the second battery cell 2 is located, and through welding can be achieved through the second welding ribbon 5 without the welding ribbon forming a bend, that is, the second welding ribbon 5 extends along the second direction. The structure of the first welding ribbon 4 and the second welding ribbon 5 after welding is as shown in FIG. Figure 6 and Figure 7 As shown in .

[0089] In the present invention, the first grid line 111 of the first battery cell 1 is further provided with at least one third electrode solder joint 116, and the first grid line 211 of the second battery cell 2 is further provided with at least one third electrode solder joint 216. Taking the first battery cell 1 as an example, there are multiple third electrode solder joints in this embodiment. The polarity of the third electrode solder joint 116 is opposite to the polarity of the front electrode solder joint 122. The projections of the first electrode solder joint 113, the second electrode solder joint 114, and the third electrode solder joint 115 in the second direction (the column direction in the figure) do not overlap. In this way, the electrode solder joints with opposite polarities have no spatial overlap, which can reduce the probability of micro-short circuits caused by alignment deviation in the metallization process.

[0090] Specifically, if Figure 4 As shown in , the third electrode solder joint 116 is located on the first grid line 111 and therefore has the same polarity as the first grid line 111. In this embodiment, the first grid line 111 is the positive electrode, so the polarity of the third electrode solder joint 116 and the first electrode solder joint 113 is positive. The polarity of the third electrode solder joint 116 is opposite to the polarity of the front electrode solder joint 222 of the top cell and is determined by the polarity of the front electrode solder joint 122. In other words, if the polarity of the front electrode solder joint of the top cell is positive, the polarity of the third electrode solder joint needs to be negative. At this time, the polarity of the first grid line needs to be set to negative. Accordingly, the polarity of the first electrode solder joint is negative and the polarity of the second electrode solder joint is positive.

[0091] Taking the first cell 1 as an example, Figure 4 As shown, in the second direction, at least one first welding point row 1131 and one second welding point row 1141 are adjacently arranged in the first direction to form an electrode pair. In this embodiment, there are multiple first welding point rows 1131, multiple second welding point rows 1141, and multiple third electrode welding points 116 are linearly arranged to form a third welding point row 11611161. In the first direction, there is at least one third welding point row 1161. Preferably, the first welding point row 1131 and the second welding point row 1141 are alternately arranged in the first direction to form multiple electrode pairs, as shown in FIG. Figure 4 As shown in Figure 4 The case of three electrode pairs is shown. At least one electrode pair among the plurality of electrode pairs is configured with a third electrode pad row. Specifically, the number of third electrode pairs can be the same as the number of electrode pairs, or can be different, such as the number of third pad rows 1161 is less than the number of electrode pairs. More preferably, Figure 4 As shown in FIG, the first soldering point row 1131, the second soldering point row 1141 and the third soldering point row 1161 are arranged in an array in the first direction. It should be noted that the array arrangement here does not limit the relative order of the first soldering point row 1131, the second soldering point row 1141 and the third soldering point row 1161. Figure 4 In addition to the sequential arrangement of third solder point row 1161, first solder point row 1131, and second solder point row 1141 shown in FIG, an arrangement of first solder point row 1131, second solder point row 1141, and third solder point row 1161 can also be arranged in this order. Alternatively, an arrangement of first solder point row 1131, third solder point row 1161, and second solder point row 1141 can be arranged in this order, and so on. This arrangement can make the resistance of each part of the cell uniform, which helps reduce the overall resistance. In this embodiment, there are three third solder point rows 1161. First solder point row 1131 and second solder point row 1141 are adjacent to form an electrode pair, and third solder point row 1161 is located on one side of the electrode pair.

[0092] In summary, the polarity of the third electrode solder joint is determined by the polarity of the front electrode solder joint of the top battery, and is opposite to the polarity of the front electrode solder joint. Its position on the back grid line is determined by the polarity of the grid line itself. The final result is that the polarity of the front electrode solder joint is opposite to the polarity of the grid line where the third electrode solder joint is located. It should be noted that the above example only shows the case where the first grid line is positive and the second grid line is negative, and the third electrode solder joint is set on the first grid line, which is to correspond to the case where the front electrode solder joint is negative. It can be understood that when the front electrode solder joint is negative, the third electrode solder joint should be set to negative, and the polarity of the first grid line should be negative.

[0093] It should be noted that the above arrangement is merely exemplary. When multiple first welding point rows 1131 and multiple second welding point rows 1141 are provided, at least some of the first welding point rows 1131 and second welding point rows 1141 may not be adjacent to each other. For example, multiple first welding point rows 1131 may be adjacent to each other, and multiple second welding point rows 1141 may be adjacent to each other. In addition, the number of first welding point rows 1131 and second welding point rows 1141 may be equal or in an odd-even relationship. The same applies to the second battery cell and will not be further described here.

[0094] In addition, the above example takes the example that each first gate line is provided with a first electrode welding point and a third electrode welding point, and the number of the two is equal, but not each first gate line needs to be provided with a third electrode welding point with the same number as the first electrode welding points. It is also possible that some first gate lines are not provided with a third electrode welding point, or the number of the third electrode welding points provided is different from the number of the first electrode welding points, etc. As long as it is ensured that there is a third electrode welding point for connecting to the front electrode welding point in the second direction, there is no limit on the number of the third electrode welding points in the second direction, and there is no limit on the number of the third electrode welding points in the first direction, such as Figure 9 As shown in . By streamlining the number of solder joints, while ensuring connection stability, streamlining the number of solder joints helps save solder joint materials.

[0095] Alternatively, in a third direction perpendicular to both the first and second directions, the projections of at least one front solder joint row and at least one third solder joint row do not overlap, and the minimum spacing L between the projections of the two in the first direction is greater than 0.01 mm and less than 1 mm. Specifically, Figure 10 As shown in Figure 10 The figure shows a situation where the projections of the front and third soldering point rows in the third direction do not overlap. Since the width of the solder ribbon is typically 0.01mm to 1mm, and for perovskite-crystalline silicon tandem cells, the mainstream solder ribbon width is 0.25–0.50mm, the minimum distance L between the projections of the front and third soldering point rows in the third direction is less than 0.5mm. This is sufficient as long as the solder ribbon can simultaneously connect to both the front and third electrode soldering points when extending in the second direction (during zigzag soldering).

[0096] Based on the above cell structure, the present invention also provides a solution for stringing cells to form a photovoltaic module. Specifically, the photovoltaic module includes multiple cell strings, each cell string includes the cells in the above example. In this embodiment, the cell strings are formed by connecting the cells in series as an example. Of course, the cell strings can also be connected in parallel or in series and parallel. The cell string in this embodiment includes at least two cells with Figure 4 A battery cell with a medium structure and a Figure 5 A battery cell having a medium structure, or at least one having Figure 4 The battery cell with medium structure and two Figure 5 It should be noted that there is no limit on the number of cells in a battery string, as long as it can be achieved within the process range. However, it is necessary to ensure that the back electrodes of adjacent cells can be welded in series, that is, there are certain requirements for the type and arrangement of the cells.

[0097] Specifically, combined Figures 6 to 8As shown, one of the two adjacent cells is defined as the first cell 1, and the other is defined as the second cell 2. The original solder joints on the back electrodes of the first cell 1 and the second cell 2 are respectively soldered by the first soldering ribbon 4 and the second soldering ribbon 5. The front electrode solder joint of the second cell 2 is soldered to the third electrode solder joint 116 of the first cell 1 by the third soldering ribbon 6, thereby forming a series structure. Figure 7 As shown in , the first welding ribbon 4 is used to connect the first welding point row 1131 formed by the linear arrangement of multiple first electrode welding points 113 on the back side of the first battery cell 1 and the second welding point row 2141 formed by the linear arrangement of multiple second electrode welding points 214 on the back side of the second battery cell 2. The second welding ribbon 5 is used to connect the second welding point row 1141 formed by the linear arrangement of multiple second electrode welding points 114 on the back side of the first battery cell 1 and the first welding point row 2131 formed by the linear arrangement of multiple first electrode welding points 213 on the back side of the second battery cell 2. The third welding ribbon 6 is used to connect the front welding point row formed by the linear arrangement of multiple front electrode welding points 222 of the second battery cell 2 and the third welding point row 1161 formed by the linear arrangement of multiple third electrode welding points 116 on the back side of the first battery cell 1. The first welding ribbon 4, the second welding ribbon 5 and the third welding ribbon 6 all extend along the second direction. Among them, the third welding ribbon 6 connects the first battery cell 1 and the second battery cell 2 in a Z-shaped welding manner. The same is true for the case of connecting three battery cells, as shown in FIG. Figure 8 As shown in FIG, the third cell 3 is located on the side of the second cell 2 away from the first cell 1. The structure of the third cell 3 is exactly the same as that of the first cell 1. The third cell 3 and the second cell 2 are connected to the original back electrode through the first welding ribbon 4 and the second welding ribbon 5. The front electrode of the third cell 3 is connected to the third electrode welding point of the second cell 2 through the third welding ribbon 6. It should be noted that, in order to facilitate the observation of the structure of the third welding ribbon 6, Figure 8 The first welding strip 4 and the second welding strip 5 are not shown in the figure.

[0098] It can be understood that although the above example only shows the situation of three battery cells welded in series, the solution of the present invention is not limited to the series welding of three battery cells. The number of battery cells can be any appropriate number, and the connection method of adjacent battery cells is the same as in the above example.

[0099] In addition to the battery cells and welding strips, photovoltaic modules also include packaging, substrate (non-flexible), edge sealant, etc., among which the packaging includes glass, film, etc.

[0100] refer to Figures 3 to 5In this embodiment, the first electrode welding spot and the second electrode welding spot form an electrode pair. In this embodiment, the original back electrode forms three electrode pairs, and the spacing between the three electrode pairs is uniform. It should be noted that the arrangement of the original back electrode is not limited to this. In the first direction, the number of first electrode welding spots can be greater than the number of second electrode welding spots, or the number of first electrode welding spots can be less than the number of second electrode welding spots. In addition, the first electrode welding spots and the second electrode welding spots can be arranged in an alternating positive and negative arrangement, or at least some of the first electrode welding spots can be adjacent to each other in the first direction, and the second electrode welding spots can be adjacent to each other in the first direction. As long as at least one first electrode welding spot and one second electrode welding spot are adjacent to each other in the first direction to form an electrode pair, the present invention does not impose any specific restrictions on the position and number of the first electrode welding spots and the second electrode welding spots in the first direction. Preferably, in the first direction, the number of first electrode welding points is one more or one less than the number of second electrode welding points, or the two are the same. Through such an arrangement, the current density difference between the front and back sides can be balanced, and the efficiency loss caused by the front / back current mismatch can be avoided (especially under non-uniform lighting conditions); in addition, the current collection network can be refined, local current congestion (such as edge effect) can be alleviated, and the problem of heat concentration caused by excessive local resistance can be avoided.

[0101] It should be noted that the number of columns of the third electrode welding points is not necessarily the same as the number of electrode pairs, and the number of columns of the third electrode welding points only needs to include at least one column.

[0102] Furthermore, if Figures 3 to 7 As shown in , in this embodiment, in the third direction, the projection of at least one front welding point row and the projection of at least one third welding point row at least partially overlap. This embodiment shows a situation where the projections of three front welding point rows and three third welding point rows (including third welding point row 1161 and third welding point row 2161) completely overlap, that is, the width of the third electrode welding point along the first direction is the same as the width of the front electrode welding point along the first direction, and the orthographic projections of the third welding point row and the front welding point row in the third direction completely overlap. It should be noted that the orthographic projections of the third welding point row and the front welding point row in the third direction do not need to completely overlap, as long as the third welding point row 6 is not bent in the first direction (row direction in the figure) during the welding process using the third welding ribbon 6, the front electrode welding point and the back third electrode welding point can be welded. It should be noted that the at least partial overlap here includes the following situations: the orthographic projection of the third electrode solder point and the front electrode solder point in the third direction completely overlap; or the orthographic projection of the third electrode solder point and the front electrode solder point in the third direction partially overlap; or there is no corresponding relationship between the orthographic projection of the third electrode solder point and the front electrode solder point, and it is sufficient to ensure that the projection of the third solder point row and the front solder point row in the third direction completely overlap or partially overlap.

[0103] This arrangement allows for more precise connection between the front electrode soldering point and the third electrode soldering point on the first gridline during cell welding. Due to the corresponding positions, the welding tool can be positioned more accurately, reducing the possibility of welding deviation and improving welding quality. This in turn ensures an efficient and stable electrical connection between the front electrode and the first gridline on the back, which is beneficial to the overall electrical performance of the cell.

[0104] Furthermore, the number of front solder joint rows is the same as the number of third solder joint rows. Through this arrangement, the same process parameters and equipment can be used to make the front and back electrode solder joints during the manufacturing process of the battery cell. This simplifies the production process, reduces the difficulty of adjustment and calibration during the production process, improves production efficiency, and also reduces product quality fluctuations caused by process differences. In addition, the design of the same number ensures that a one-to-one corresponding connection relationship can be formed between the front electrode solder joint and the third electrode solder joint on the back, so that the current can be evenly distributed when it is transmitted from the front electrode to the first grid line on the back. This avoids the problem of current concentration or uneven dispersion caused by the mismatch in the number of solder joints, and further improves the electrical performance stability and reliability of the battery cell.

[0105] In the embodiment of the present invention, Figure 4 As shown, in the second direction (column direction in the figure), an insulating glue dot 115 is provided on the first gate line 111 and at a position corresponding to the second electrode solder point 114, and an insulating glue dot 115 is provided on the second gate line 112 and at a position corresponding to the first electrode solder point 113 and the third electrode solder point 116. It should be noted that if two insulating glue dots are adjacent in the first direction (row direction in the figure), they can be connected into one insulating glue dot. The types of insulating glue include epoxy resin glue, organic silicone glue, polyurethane glue, etc. Before dispensing or applying glue through a screen, it is necessary to ensure that the surface of the substrate is clean. Since the process of dispensing or applying glue is already a relatively mature existing technology, it will not be repeated here. Figure 5 As shown, an insulating glue dot 215 is provided on the first gate line 211 at a position corresponding to the second electrode pad 214 , and an insulating glue dot 215 is provided on the second gate line 212 at a position corresponding to the first electrode pad 213 and the third electrode pad 216 .

[0106] It should be noted that the bottom cell in the perovskite-crystalline silicon stacked cell in the above example is described using an IBC cell (Interdigitated Back Contact) as an example, and may also be a TBC cell (TOPCon Back Contact) or an HBC cell (Heterojunction Back Contact). In addition, the above example is described using a back contact cell without a main grid as an example, and the solution of the present invention is also applicable to back contact cells with a main grid, that is, the first electrode solder joints of each cell are connected to the main grid and then to the soldering ribbon, and the second electrode solder joints are connected to the main grid and then to the soldering ribbon.

[0107] In addition, the top cell in the above example is illustrated using a perovskite cell as an example. In addition, the top cell can also be CdTe (Cadmium Telluride), CIGS (Copper Indium Gallium Selenide), CZTS (Copper Zinc Tin Sulfide), etc., and accordingly, it can form a cadmium telluride-crystalline silicon stacked cell, or a copper indium gallium selenide-crystalline silicon stacked cell, or a copper zinc tin sulfur-crystalline silicon stacked cell with the bottom cell.

[0108] It should be noted that when forming a multi-junction cell with more than two, such as a three-junction cell or a four-junction cell, the bottom cell uses a crystalline silicon cell, and the top cell and the middle cell can use any combination of the above cells, such as a double perovskite-crystalline silicon stacked cell.

[0109] To produce the battery cell in the aforementioned example, the present invention also provides a printing screen for printing the back electrode of the battery cell. It should be noted that the printing of the back electrode of the battery cell can be carried out in steps or in one go.

[0110] For example, this embodiment provides a printing screen for printing grid lines and solder joints at one time. It is understandable that the screen used to print the back electrode of the first cell 1 is different from the screen used to print the back electrode of the second cell 2.

[0111] like Figure 11 As shown, Figure 11The printing screen for printing the first battery cell 1 is shown, which is defined as the first printing screen 71. The first printing screen 71 includes a screen base, on which at least one first grid line pattern 711 and at least one second grid line pattern 712 extending along a first direction are provided. In this embodiment, a plurality of first grid line patterns 711 and a plurality of second grid line patterns 712 extending along the first direction are provided on the screen base as an example. The plurality of first grid line patterns 711 and the plurality of second grid line patterns 712 extend continuously in the first direction. The first grid line patterns 711 and the second grid line patterns 712 are spaced and alternately arranged along a second direction perpendicular to the first direction. The screen base is also provided with at least one first welding point pattern 713, at least one second welding point pattern 714, and at least one third welding point pattern 715. In this embodiment, a plurality of first welding point patterns 713, a plurality of second welding point patterns 714, and a plurality of third welding point patterns 715 are provided on the screen base as an example for description. In a direction perpendicular to the screen substrate, the projections of the first solder joint pattern 713 and the third solder joint pattern 715 fall on the projection of the first grid line pattern 711, forming a strip-shaped hollow pattern including the first grid line pattern, the first solder joint pattern, and the third solder joint pattern. The projection of the second solder joint pattern 714 falls on the projection of the second grid line pattern 712, forming a strip-shaped hollow pattern including the second grid line pattern and the second solder joint pattern. The projections of the first solder joint pattern, the second solder joint pattern, and the third solder joint pattern in the second direction do not overlap.

[0112] like Figure 12 As shown, Figure 12 The screen structure for printing the back electrode of the second battery cell 2 is shown, which is defined as the second printed screen 72. Specifically, the second printed screen 72 includes a screen substrate, on which a plurality of first grid line patterns 721 and a plurality of second grid line patterns 722 extending along a first direction are provided. The first grid line patterns 721 and the second grid line patterns 722 are spaced and alternately arranged along a second direction perpendicular to the first direction. The screen substrate is also provided with a plurality of first welding point patterns 723, a plurality of second welding point patterns 724, and at least one third welding point pattern 725. In the third direction, that is, the direction perpendicular to the screen substrate, the projections of the first welding point pattern 723 and the third welding point pattern 725 fall on the projection of the first grid line pattern 721, forming a strip-shaped hollow pattern including the first grid line pattern 721, the first welding point pattern 723, and the third welding point pattern 725. The projection of the second solder joint pattern 724 falls on the projection of the second grid line pattern 722, forming a stripe hollow pattern including the second grid line pattern 722 and the second solder joint pattern 724. The projections of the first solder joint pattern 723, the second solder joint pattern 724 and the third solder joint pattern 725 in the second direction do not overlap. Figure 11 The difference is that, in the first direction, the first solder joint pattern and the second solder joint pattern are located at different positions and correspond to each other.

[0113] In addition to printing in one go, the back electrode of the cell can also be printed in steps, first printing the grid lines and then printing the solder joints. Accordingly, a screen assembly is required to achieve step-by-step printing. Specifically, another screen embodiment is also provided. Figures 13 to 15 As shown, the back electrode of the first cell 1 needs to be printed in combination with the third printing screen 73 and the fourth printing screen 74, and the back electrode of the second cell 2 needs to be printed in combination with the third printing screen 73 and the fifth printing screen 75. That is, in the case of a preparation process using step-by-step electrode printing, the back electrode of each cell requires at least two screens, and the patterns on the two screens are different, and the patterns are distributed on the first screen substrate and the second screen substrate respectively.

[0114] Combine Figure 13 and Figure 14 , forming a screen group for preparing the first battery cell 1. Figure 13 As shown in , it shows a screen for printing the grid lines in the back electrode. The third printing screen 73 includes a first screen substrate (not shown), on which a plurality of first grid line patterns 731 and a plurality of second grid line patterns 732 extending along a first direction are provided. The first grid line patterns 731 and the second grid line patterns 732 are spaced and alternately arranged along a second direction perpendicular to the first direction. The screen can be used to print the first grid lines and the second grid lines in the back electrodes of the first battery cell 1 and the second battery cell 2. As shown in Figure 14 As shown, the fourth printing screen 74 is used to print the solder joints in the back electrode of the first battery cell 1. The fourth printing screen 74 includes a second screen substrate, on which a first solder joint pattern 741, a second solder joint pattern 742 and a third solder joint pattern 743 are provided. When the first screen substrate and the second screen substrate are aligned, the projections of the first solder joint pattern 741 and the third solder joint pattern 743 fall on the projection of the first grid line pattern 731, and the projection of the second solder joint pattern 742 falls on the projection of the second grid line pattern 732. The projection structure of the screen group formed after the two are aligned can be referred to. Figure 4 (Omit the insulating glue dots).

[0115] Combine Figure 13 and Figure 15 , forming a screen group for preparing the second battery sheet 2. Figure 15As shown, the fifth printing screen 75 is used to print the solder joints in the back electrode of the second battery cell 2. The fifth printing screen 75 includes a second screen substrate, on which a first solder joint pattern 751, a second solder joint pattern 752, and a third solder joint pattern 753 are provided. When the first screen substrate and the second screen substrate are aligned, the projections of the first solder joint pattern 751 and the third solder joint pattern 753 fall on the projection of the first grid line pattern 731, and the projection of the second solder joint pattern 752 falls on the projection of the second grid line pattern 732. The projection structure of the screen group formed after the two are aligned can be referred to. Figure 5 (Omit the insulating glue dots).

[0116] Furthermore, if Figure 14 As shown, in this embodiment, the fourth printing screen 74 is used to print the solder joints on the back electrode of the first solar cell 1. Specifically, in the second direction, a plurality of first solder joint patterns are linearly arranged to form a first pattern row 7411, a plurality of second solder joint patterns are linearly arranged to form a second pattern row 7421, and a plurality of third solder joint patterns are linearly arranged to form a third pattern row 7431. At least one first pattern row 7411 and one second pattern row 7421 are adjacent to each other in the first direction. Preferably, the first pattern row 7411 and the second pattern row 7421 are arranged alternately in the first direction. After the third pattern row 7431 is added, the first pattern row 7411, the second pattern row 7421, and the third pattern row 7431 are arranged in an array to adaptively produce the back electrode of the first solar cell or the back electrode of the second solar cell.

[0117] The above-mentioned printing screen is used to prepare the back electrode of the bottom cell of the stacked cell. The prepared stacked cell is the perovskite-crystalline silicon stacked cell in the above example. The bottom cell of the perovskite-crystalline silicon stacked cell is a back contact cell and is a three-terminal stacked cell.

[0118] It should be noted that the technical solution of the present invention is also applicable to three-junction three-terminal stacked cells, four-junction three-terminal stacked cells, etc. Regardless of the number of junctions in the cell, the front electrode of the top cell is arranged in the same manner as the front electrode of the perovskite-crystalline silicon stacked cell in the above example, and the back electrode of the bottom cell is arranged in the same manner as the back electrode of the bottom cell of the perovskite-crystalline silicon stacked cell in the above example. The difference lies in the structure of the middle part of the cell, such as Figure 16 As shown, Figure 16The structure of a three-junction, three-terminal tandem cell is shown. The back electrode of the bottom cell is identical to that of the bottom cell of the perovskite-crystalline silicon tandem cell provided in the embodiments of the present invention, as is the back electrode structure, with the addition of a third electrode solder joint. The top cell structure is identical to that of the top cell of the perovskite-crystalline silicon tandem cell, as is the front electrode. The difference is that the three-junction tandem cell adds a perovskite cell between the top and bottom cells of the two-junction tandem cell. The top cell uses a wide-bandgap perovskite, while the middle cell uses a medium-bandgap perovskite.

[0119] It should be noted that the components of the various layers of the battery cell in the above examples are merely exemplary, and the structure of the back electrode of the present invention is also applicable to three-terminal stacked battery cells of other structures.

[0120] In the above example, the screen substrate (including the first screen substrate and the second screen substrate in the case of step-by-step printing) can be a metal substrate or a polymer substrate. In addition, each grid line pattern and each solder joint pattern are hollow patterns. In the process of printing the back electrode, it is necessary to print the solder joints after printing the grid lines, and the screen for printing the solder joints and the screen for printing the grid lines need to ensure alignment accuracy. In addition, although the shape of the solder joint pattern in each figure is a rectangle, this is not restrictive, and the shape of each solder joint pattern can also be a square, a circle, an ellipse, etc.

[0121] The present invention also provides a method for preparing a laminated battery cell. Taking step-by-step printing as an example, when preparing the back electrode of a BC battery, it is necessary to use a grid line screen and a solder point screen for step-by-step printing. Grid line printing usually uses silver paste because it has good conductivity. Silver powder, organic carrier, solvent, etc. are mixed in a certain proportion and prepared into a uniform silver paste through stirring, grinding and other processes. For solder point printing, suitable solder paste can be selected according to specific needs, such as low-temperature solder paste containing tin, lead and other components, and prepared according to the corresponding formula. Taking the printing of the back electrode of the first battery cell by step-by-step printing as an example, the following steps are included:

[0122] S10, forming first gate lines and second gate lines extending along a first direction on the back side of the battery cell, wherein the first gate lines and the second gate lines are arranged at intervals along a second direction perpendicular to the first direction.

[0123] Specifically, when printing the grid lines, the third printing screen needs to be installed on the screen printing machine, and the tension of the screen needs to be adjusted to ensure that the screen is flat, without slack or wrinkles, so as to ensure the accuracy of printing. The third printing screen is then positioned so that it is accurately aligned with the position of the battery cell, which can be achieved by an optical positioning system or a mechanical positioning device. The printing operation places an appropriate amount of silver paste on a specific area of ​​the battery cell, usually by automatic dispensing or scraper pre-coating. Start the screen printing machine, and the scraper moves on the screen with a certain pressure and speed, squeezing the silver paste from the pattern part of the screen to the surface of the battery cell to form a grid line pattern. After the grid line printing is completed, the battery cell is placed in a drying device and dried at an appropriate temperature (such as 150-200°C) to evaporate the organic solvent in the silver paste and preliminarily solidify the silver paste.

[0124] S20, forming at least one first electrode pad and at least one third electrode pad on the first gate line, and forming at least one second electrode pad on the second gate line, wherein projections of the first electrode pad, the second electrode pad, and the third electrode pad in the second direction do not overlap.

[0125] Specifically, after the grid lines are printed, the solder joints are printed. First, the third printing screen is removed from the printing machine and replaced with the fourth printing screen. The fourth printing screen also needs to be positioned to ensure that it accurately corresponds to the position of the battery cell and the printed grid lines. During the printing operation, an appropriate amount of solder paste is placed at the position where the solder joints need to be formed on the battery cell. The screen printing machine is started, and the solder paste is printed onto the surface of the battery cell by the action of a scraper to form each solder joint. Specifically, a plurality of first electrode solder joints and a plurality of third electrode solder joints are formed on the first grid line, and a plurality of second electrode solder joints are formed on the second grid line. The projections of the first electrode solder joints, the second electrode solder joints and the third electrode solder joints in the second direction do not overlap. After printing the solder joints, the battery cell is dried to remove the solvent in the solder paste.

[0126] After the back electrode is printed, a pre-sintering process is carried out to pre-sinter the solder joints at a relatively low temperature (such as 200-250°C) so that the solder can initially form intermetallic compounds, thereby improving the strength and conductivity of the solder joints and preparing for subsequent welding processes.

[0127] It is understandable that the preparation process of the back electrode of the second battery cell and the front electrode of the perovskite top battery is similar.

[0128] In addition to step-by-step printing, the back electrode can also be printed by one-time printing, which is achieved by using an integrated screen. During the printing process, the gate lines and solder joints are printed simultaneously, which will not be described in detail here.

[0129] It should be noted that, although the grid lines in the figure intersect with the frame, in actual application there is a certain gap between the grid lines and the edge of the solar cell substrate.

[0130] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A laminated battery cell, characterized in that: The front of the cell is provided with at least one front grid line, and at least one front electrode welding point is provided on the at least one front grid line. The back side of the battery cell includes: At least one first gate line and at least one second gate line extending along a first direction, wherein the first gate line and the second gate line are arranged at intervals along a second direction perpendicular to the first direction; The first gate line is provided with at least one first electrode pad, and the second gate line is provided with at least one second electrode pad, wherein the polarity of the first electrode pad is opposite to that of the second electrode pad; Among them, at least one of the first gate lines is also provided with at least one third electrode solder joint, the polarity of the third electrode solder joint is opposite to the polarity of the front electrode solder joint, and the projections of the first electrode solder joint, the second electrode solder joint and the third electrode solder joint in the second direction do not overlap.

2. The laminated battery cell according to claim 1, characterized in that: In the first direction, the first gate line and the second gate line extend continuously.

3. The laminated battery cell according to claim 1, wherein: In the second direction, a plurality of the front electrode solder joints are linearly arranged to form a front solder joint row, and a plurality of the third electrode solder joints are linearly arranged to form a third solder joint row; In the first direction, there is at least one front solder joint row and at least one third solder joint row. In a third direction perpendicular to both the first direction and the second direction, the projections of at least one of the front solder joint rows and at least one of the third solder joint rows do not overlap, and a minimum spacing L between the projections of the two in the first direction is greater than 0.01 mm and less than 1 mm; or In a third direction perpendicular to both the first direction and the second direction, a projection of at least one of the front welding spot rows at least partially overlaps with a projection of at least one of the third welding spot rows.

4. The laminated battery cell according to claim 3, characterized in that: The number of the front welding point rows is the same as the number of the third welding point rows.

5. The laminated battery cell according to claim 1, characterized in that: In the second direction, an insulating glue spot is provided on the first gate line at a position corresponding to the second electrode welding spot, and an insulating glue spot is provided on the second gate line at a position corresponding to the first electrode welding spot and the third electrode welding spot.

6. The laminated battery cell according to claim 1, characterized in that: In the second direction, multiple first electrode welding spots are linearly arranged to form a first welding spot row, multiple second electrode welding spots are linearly arranged to form a second welding spot row, and at least one first welding spot row and one second welding spot row are adjacently arranged in the first direction to form an electrode pair.

7. The laminated battery cell according to claim 6, characterized in that: The first welding point rows and the second welding point rows are alternately arranged in the first direction to form a plurality of electrode pairs, and at least one electrode pair of the plurality of electrode pairs is configured with one of the third electrode welding point rows.

8. The laminated battery cell according to claim 7, characterized in that: The first welding point row, the second welding point row and the third welding point row are arranged in an array in the first direction.

9. The laminated battery cell according to claim 1, characterized in that: The stacked cell is a perovskite-crystalline silicon stacked cell, or a cadmium telluride-crystalline silicon stacked cell, or a copper indium gallium selenide-crystalline silicon stacked cell, or a copper zinc tin sulfur-crystalline silicon stacked cell.

10. The laminated battery cell according to any one of claims 1 to 9, characterized in that: The laminated cell sheet comprises at least a top cell and a bottom cell stacked in layers, wherein the bottom cell is a back contact cell; and / or The stacked battery cell is a three-terminal stacked battery cell.

11. A battery string, characterized in that: The battery string includes the stacked battery sheet according to any one of claims 1 to 10.

12. A photovoltaic module, characterized in that: The photovoltaic module comprises the cell string according to claim 11.

13. The photovoltaic module according to claim 12, characterized in that: In the second direction, the plurality of first electrode welding points of the stacked battery cell are linearly arranged to form a first welding point row, the plurality of second electrode welding points are linearly arranged to form a second welding point row, the plurality of third electrode welding points are arranged to form a third welding point row, and the plurality of front electrode welding points are arranged to form a front welding point row. The battery string also includes a first welding strip, a second welding strip and a third welding strip extending along the second direction. The first welding strip is used to connect the first welding point row on the back of one battery cell of two adjacent battery cells with the second welding point row on the back of the other battery cell. The second welding strip is used to connect the second welding point row on the back of the one battery cell with the first welding point row on the back of the other battery cell. The third welding strip is used to connect the front welding point row of the one battery cell with the third welding point row on the back of the other battery cell.

14. A printing screen, characterized in that: The printing screen includes a screen base, on which at least one first grid line pattern and at least one second grid line pattern extending along a first direction are provided, wherein the first grid line pattern and the second grid line pattern are arranged at intervals along a second direction perpendicular to the first direction; The screen substrate is also provided with at least one first welding point pattern, at least one second welding point pattern, and at least one third welding point pattern. In the third direction, the projections of the first welding point pattern and the third welding point pattern fall on the projection of the first grid line pattern, and the projection of the second welding point pattern falls on the projection of the second grid line pattern. The projections of the first welding point pattern, the second welding point pattern and the third welding point pattern in the second direction do not overlap, and the third direction is perpendicular to the first direction and the second direction.

15. The printing screen according to claim 14, wherein: The screen substrate includes a first screen substrate and a second screen substrate that are adapted to each other. The first grid line pattern and the second grid line pattern are arranged on the first screen substrate. The first welding point pattern, the second welding point pattern and the third welding point pattern are arranged on the second screen substrate.

16. The printing screen according to claim 15, characterized in that The first gate line pattern and the second gate line pattern extend continuously in the first direction.

17. The printing screen according to any one of claims 14 to 16, characterized in that In the second direction, multiple first welding point patterns are linearly arranged to form a first pattern row, multiple second welding point patterns are linearly arranged to form a second pattern row, and multiple third welding point patterns are linearly arranged to form a third pattern row. At least one first pattern row and one second pattern row are adjacent to each other in the first direction.

18. The printing screen according to claim 17, wherein: The first pattern rows and the second pattern rows are alternately arranged in the first direction.

19. The printing screen according to claim 18, wherein: The first pattern row, the second pattern row and the third pattern row are arranged in an array in the first direction.

20. The printing screen according to claim 1, wherein The printing screen is used to prepare the back electrode of the bottom cell of the laminated cell, and the bottom cell of the laminated cell is a back contact cell; and / or The stacked battery cell is a three-terminal stacked battery cell.

21. A method for preparing a laminated battery cell, characterized in that: A battery cell is prepared using the printing screen according to any one of claims 14 to 20, wherein the battery cell is the laminated battery cell according to any one of claims 1 to 10.

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