TOPCon battery

Abstract

The utility model provides a TOPCon battery, which ingeniously isolates direct contact between grid lines by introducing a heightened material layer between the grid lines of a battery piece, specifically adopting an efficiently cured UV (ultraviolet) adhesive (structural adhesive), and fundamentally solves the common problem of falling off of front fine grids on the current TOPCon production line, so that the production efficiency of the TOPCon battery is greatly improved, and the production cost of the TOPCon battery is reduced. And the reliability and durability of the battery assembly are obviously improved. And secondly, the damage to the grid lines caused by mutual friction between the front grid line and the back grid line is effectively prevented, the integrity of the grid line structure is protected, the stability and the long-term property of the conversion efficiency of the battery are further ensured, and the improvement not only prolongs the service life of the battery, but also reduces the maintenance cost caused by the damage of the grid lines. Besides, the adopted UV adhesive material has the characteristic of rapid curing, so that the reinforcement operation can be rapidly completed on the premise of not influencing the production rhythm of the existing production line, the additional production time is hardly increased, and the continuous optimization of the production efficiency is ensured.

Description

Technical Field

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

[0002] Against the backdrop of the rapid development of the photovoltaic industry, TOPCon (Tunnel Oxide Passivated Contact) cells have attracted much attention due to their high efficiency, low attenuation and good process compatibility.

[0003] However, with the introduction of the LECO (Local Etching Contact Opening) process, the production process for TOPCon cells and the demand for its key material, silver paste, have undergone significant changes. The LECO process, an innovative technology, aims to form silver-silicon alloy contacts directly on the silicon substrate by locally etching the passivation layer, thereby creating efficient current transmission channels. This change places new demands on the performance of the silver paste.

[0004] The design of traditional TOPCon battery silver paste focuses on comprehensive passivation layer etching and good silver sintering performance to ensure strong adhesion of the silver grid lines to the silicon wafer and efficient current collection. In contrast, LECO silver paste significantly reduces the need for comprehensive etching of the passivation layer and instead focuses on local precision etching. This change requires the silver paste to have a lower glass content or a higher glass transition temperature (Tg) to reduce the potential impact on the surrounding non-etched areas. However, the low glass content, high glass transition temperature (Tg), poor fluidity and weak passivation layer etching ability of LECO silver paste directly lead to insufficient silver sintering, which in turn affects the adhesion between the silver grid lines and the silicon wafer.

[0005] Furthermore, because TOPCon cells require silver paste printing on both sides and are stacked after testing and binning, this physical layout makes the front and back secondary grid lines highly susceptible to friction. Under the LECO process, the adhesion between the silver grid lines and the silicon wafer is weakened, making the front secondary grid lines more susceptible to scratching and detachment from the back secondary grid lines during the stacking process, significantly increasing the cell defect rate. This problem not only affects the yield rate of TOPCon cells but also increases production costs, posing a challenge to the production efficiency and economic benefits of photovoltaic companies. Utility Model Content

[0006] In order to solve at least one of the problems raised in the above technical background, the present application provides a TOPCon battery, comprising:

[0007] At least two stacked cells, each cell having a laminated passivation structure, including an N-type silicon wafer, wherein the upper surface of the N-type silicon wafer is provided with an aluminum oxide layer and a silicon nitride layer from the inside out, and the lower surface thereof is provided with a silicon oxide layer, a phosphorus-doped polysilicon layer, an aluminum oxide layer, and a silicon nitride layer from the inside out;

[0008] Fine grid, including front fine grid and back fine grid,

[0009] Each cell is equipped with at least two front thin grids on the front side.

[0010] The back of each cell is equipped with at least two back thin grids;

[0011] The heightening structure includes structural glue and is disposed between two adjacent battery cells. The height of the structural glue allows a gap to be left between the front fine grid and the back fine grid on the opposite surfaces of the two adjacent battery cells.

[0012] In a preferred embodiment, the thickness of the silicon oxide layer is 0.5-5 nm, preferably 1-4 nm, and more preferably 2-3 nm.

[0013] In a preferred embodiment, the thickness of the phosphorus-doped polysilicon layer is 80-150 nm, preferably 90-140 nm, and more preferably 110-130 nm.

[0014] In a preferred embodiment, the thickness of the aluminum oxide layer is 5-50 nm, preferably 10-40 nm, and more preferably 20-30 nm.

[0015] In a preferred embodiment, the thickness of the silicon nitride layer is 20-80 nm, preferably 30-70 nm, and more preferably 40-60 nm.

[0016] In a preferred embodiment, the height of the front fine grid is 1-15 μm, preferably 2-12 μm, and more preferably 3-10 μm.

[0017] In a preferred embodiment, the height of the back surface fine grid is 1-15 μm, preferably 2-12 μm, and more preferably 3-10 μm.

[0018] In a preferred embodiment, the height of the heightened structure is designed to be 5-70 μm, preferably 10-60 μm, and more preferably 20-50 μm.

[0019] In a preferred embodiment, the structural adhesive is cured by ultraviolet light.

[0020] Preferably, the structural adhesive has a curing time of 3s-10s, can be cured quickly, and has little impact on the production efficiency of the production line.

[0021] In a preferred embodiment, the structural adhesive is required to be colorless and transparent, allowing light to pass through and the battery cell to absorb light energy.

[0022] Preferably, the light transmittance of the structural adhesive after curing is between 85% and 95%.

[0023] In a preferred embodiment, the viscosity of the structural adhesive is 500 cps-40,000 cps@25°C, preferably 800 cps-30,000 cps@25°C, and more preferably 1,000 cps-20,000 cps@25°C.

[0024] In a preferred embodiment, the thixotropy of the structural adhesive is 0.5-8, preferably 1-6, and more preferably 2-5.

[0025] In a preferred embodiment, the surface drying performance of the structural adhesive is: when a 50g weight is used to press a battery cell onto the cured structural adhesive, the battery cell does not stick to the adhesive point, thereby preventing the battery cell from sticking to the adhesive point.

[0026] In a preferred embodiment, the method for applying the structural adhesive comprises the following steps:

[0027] providing a structural adhesive;

[0028] On the surface of the cell (compared to the back of the cell, the front side looks darker and more uniform, while the back side is slightly lighter), glue dots are placed along the direction of the fine grids between the two fine grids;

[0029] UV curing structural adhesive.

[0030] In a preferred embodiment, the distance between the glue points is controlled to be 3-75 mm, preferably 8-60 mm, and more preferably 10-50 mm, so as to ensure that the distribution of the glue points is both economical and effective and can provide a good bonding effect.

[0031] Preferably, the glue dots may be evenly distributed or randomly distributed.

[0032] More preferably, in order to save costs and material usage, the diameter of the glue dot should be smaller than the distance between two adjacent grid lines.

[0033] More preferably, the diameter of the glue dots is 0.1-1.5 mm, preferably 0.3-1.2 mm, and more preferably 0.5-1 mm, so as to reduce the amount of glue used and keep the surface of the battery cell neat and smooth.

[0034] In a preferred embodiment, the gluing method includes printing or dispensing.

[0035] In a preferred embodiment, before applying glue to the battery cell, it is also necessary to determine the glue application surface.

[0036] Preferably, before determining the glue application position, it is necessary to determine whether to apply the glue on the front side or the back side of the battery cell.

[0037] Preferably, the adhesive application surface is the back side of the cell, so as to avoid the decrease in light transmittance and the impact on appearance caused by applying adhesive on the front side of the cell.

[0038] In a preferred embodiment, when applying glue on the front side, UV glue with high light transmittance is selected, and it is ensured that the surface after gluing is smooth and has no obvious glue marks, so as to reduce the impact on light absorption and appearance.

[0039] Preferably, the distance between the glue spots is 5-80 mm, preferably 8-60 mm, and more preferably 10-50 mm.

[0040] In a preferred embodiment, in order to save costs, the diameter of the glue dot is smaller than the distance between two adjacent fine grids.

[0041] In a preferred embodiment, the distance between two adjacent fine grids is 0.5-1.5 mm, preferably 0.8-1.2 mm, and more preferably 0.9 mm-1.1 mm.

[0042] Preferably, the diameter of the glue dots is 0.1-2 mm, preferably 0.2-1.5 mm, and more preferably 0.3-1 mm.

[0043] In a preferred embodiment, the structural adhesive is an adhesive tape, and the adhesive tape is arranged between the fine grids and along the length direction of the fine grids.

[0044] Preferably, the height of the adhesive tape is 10-80 μm, preferably 15-65 μm, more preferably 20-50 μm.

[0045] More preferably, the thermal decomposition temperature of the adhesive tape is not lower than 200° C., preferably not lower than 250° C., and more preferably not lower than 300° C., so as to avoid melting deformation during subsequent battery cell welding and lamination.

[0046] In this application specification, thixotropy characterizes the flow properties of glue. The higher the thixotropy, the less likely it is to flow in a static state.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] This utility model provides a TOPCon battery that achieves multiple technical benefits by introducing a heightened material layer between the cell grid lines—specifically, using a highly efficient, curing UV adhesive (structural adhesive). First, this design cleverly isolates the grid lines from direct contact, fundamentally resolving the common problem of front-side fine grid detachment on current TOPCon production lines and significantly improving the reliability and durability of the battery assembly.

[0049] Secondly, the utility model effectively prevents damage to the grid lines themselves caused by friction between the front and back grid lines, protecting the integrity of the grid line structure and thus ensuring the stability and long-term performance of the battery conversion efficiency. This improvement not only extends the battery life but also reduces maintenance costs caused by grid line damage.

[0050] More importantly, the UV adhesive used has fast-curing properties, allowing for rapid completion of reinforcement operations without disrupting the existing production line, adding virtually no additional production time and ensuring continuous optimization of production efficiency. Therefore, this new design not only refines production details but also enhances the overall performance of the TOPCon product. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 paying any creative work.

[0052] Figure 1 This is a schematic structural diagram of the TOPCon battery in Example 1 of the present utility model.

[0053] Figure 2 This is a schematic structural diagram of the battery cell 2 in the TOPCon battery in Example 1 of the present utility model.

[0054] The following are the descriptions of the reference numerals:

[0055] 1. Front fine grid; 2. Solar cell; 3. Back fine grid; 4. Structural adhesive; 21. Silicon oxide layer; 22. Phosphorus-doped polysilicon layer; 23. Aluminum oxide layer; 24. Silicon nitride layer. DETAILED DESCRIPTION

[0056] This application provides a TOPCon battery. To make the purpose, technical solution, and effects of this application more clear and explicit, the application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only intended to illustrate the content of this application and are not intended to limit the content of this application.

[0057] It should be noted that the terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this manner are interchangeable under appropriate circumstances. In addition, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to these processes, methods, products, or apparatuses.

[0058] Example 1:

[0059] This embodiment provides a TOPCon battery, such as Figure 1 Shown, including:

[0060] At least two stacked cells 2: Each cell 2 employs a laminated passivation structure, primarily consisting of an N-type silicon wafer and multiple thin films on its surface. Specifically, the upper surface of the N-type silicon wafer is formed from the inside out with an aluminum oxide layer 23 and a silicon nitride layer 24, while the lower surface is formed from the inside out with a silicon oxide layer 21, a phosphorus-doped polysilicon layer 22, an aluminum oxide layer 23, and a silicon nitride layer 24.

[0061] in:

[0062] (1) Silicon oxide layer 21: with a thickness of 2-3 nm, it plays the role of preliminary passivation and protection of the silicon wafer surface.

[0063] (2) Phosphorus-doped polysilicon layer 22: with a thickness of 110-130 nm, doped with an appropriate amount of phosphorus or boron and other elements to adjust the conductivity and optimize the interface characteristics.

[0064] (3) Aluminum oxide layer 23: with a thickness of 20-30 nm, further enhancing the passivation effect and improving battery performance.

[0065] (4) Silicon nitride layer 24: with a thickness of 40-60 nm, as the outermost layer, it has good anti-reflection and surface passivation properties.

[0066] Fine grid, including front fine grid 1, back fine grid 3,

[0067] Among them, front fine grids 1: at least two front fine grids 1 are provided on the front side of each battery cell 2, and the height of the front fine grids 1 is 3-10 μm to ensure efficient current collection.

[0068] Back fine grids 3: At least two back fine grids 3 are also provided on the back side of each cell 2. The height of the back fine grids 3 is the same as that of the front fine grids 1 to avoid friction damage caused by the height difference between the front and back sides.

[0069] Heightening structure (structural adhesive 4):

[0070] Material selection:

[0071] (1) Select high-efficiency curing UV glue as structural adhesive, which has a curing time of 3s-10s and can cure quickly without affecting the production efficiency of the production line.

[0072] (2) Structural adhesive 4 is required to be colorless and transparent, with a light transmittance between 85% and 95% to ensure minimal impact on light transmission.

[0073] (3) Viscosity and thixotropy of structural adhesive 4: The viscosity of structural adhesive 4 is controlled within the range of 500 cps-40,000 cps @ 25°C, preferably 1,000 cps-20,000 cps @ 25°C; the thixotropy value is between 2 and 5 to ensure good fluidity and stability.

[0074] (4) The height of the structural adhesive 4 is such that a gap is left between the front fine grid 1 and the back fine grid 3 on the opposite surfaces of two adjacent battery cells 2. The height of the structural adhesive 4 is 20-50 μm.

[0075] (5) Surface drying performance: The cured structural adhesive 4 exhibits excellent surface drying performance. Even when a 50g weight is used to press the battery cell 2 onto the cured glue, the battery cell 2 will not stick to the glue point, thereby avoiding damage or contamination to the surface of the battery cell 2.

[0076] Structural Adhesive 4 Application Method: On the back side of cell 2 (the adhesive application surface), evenly distribute adhesive dots along the fine grids (front fine grid 1, back fine grid 3). Dots should be spaced 10-50 mm apart and kept within a 0.5-1 mm diameter to save costs and material usage. Adhesive can be applied using printing or dispensing techniques.

[0077] In a preferred embodiment, the TOPCon cell uses adhesive tape to prevent scratches on the grid lines. Specifically, high-temperature-resistant tape is placed between the grid lines. The tape has a height of 20-50 μm and a thermal decomposition temperature of no less than 300°C to prevent melting deformation during subsequent cell welding and lamination. In some embodiments, the TOPCon cell's heightened structure includes both adhesive dots and tape.

[0078] Through the above design, the TOPCon cell of this embodiment not only effectively solves the problems of fine grid shedding and friction damage between the front and back grid lines, but also significantly improves the reliability and durability of the battery module. Furthermore, the use of fast-curing UV adhesive ensures production efficiency, providing strong support for the production benefits of photovoltaic companies.

[0079] The specific embodiments of the present application have been described in detail above, but these are merely examples, and the present application is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present application are also within the scope of the present invention. Therefore, equivalent changes and modifications made without departing from the spirit and scope of the present application should be included within the scope of the present invention.

Claims

1. A TOPCon battery, characterized in that: include: At least two stacked cells, each cell having a laminated passivation structure, including an N-type silicon wafer, wherein the upper surface of the N-type silicon wafer is provided with an aluminum oxide layer and a silicon nitride layer from the inside out, and the lower surface thereof is provided with a silicon oxide layer, a phosphorus-doped polysilicon layer, an aluminum oxide layer, and a silicon nitride layer from the inside out; Fine grid, including front fine grid and back fine grid, Each cell is equipped with at least two front thin grids on the front side. The back of each cell is equipped with at least two back thin grids; The heightening structure includes structural glue and is disposed between two adjacent battery cells. The height of the structural glue allows a gap to be left between the front fine grid and the back fine grid on the opposite surfaces of the two adjacent battery cells.

2. The TOPCon battery according to claim 1, characterized in that The height of the raised structure is 5-70 μm.

3. The TOPCon battery according to claim 2, characterized in that The height of the heightened structure is 10-60 μm.

4. The TOPCon battery according to claim 3, characterized in that The height of the heightened structure is 20-50 μm.

5. The TOPCon battery according to claim 1, characterized in that The light transmittance of the structural adhesive is between 85% and 95%.

6. The TOPCon battery according to claim 1, characterized in that The structural adhesive has a viscosity of 500 cps-40,000 cps @ 25°C.

7. The TOPCon battery according to claim 6, characterized in that The structural adhesive has a viscosity of 800 cps-30,000 cps @ 25°C.

8. The TOPCon battery according to claim 7, characterized in that The structural adhesive has a viscosity of 1000 cps-20000 cps@25°C.

9. The TOPCon battery according to claim 1, characterized in that The thixotropy of the structural adhesive is 0.5-8.

10. The TOPCon battery according to claim 9, characterized in that The thixotropy of the structural adhesive is 1-6.

11. The TOPCon battery according to claim 10, characterized in that The thixotropy of the structural adhesive is 2-5.

12. The TOPCon battery according to claim 1, characterized in that The structural glue is arranged in the interval between two of the fine grids, and glue dots are arranged along the direction of the fine grids, and the diameter of the glue dots is smaller than the distance between two adjacent grid lines.

13. The TOPCon battery according to claim 12, characterized in that The diameter of the glue dots is 0.1-1.5 mm.

14. The TOPCon battery according to claim 13, characterized in that The diameter of the glue dots is 0.3-1.2 mm.

15. The TOPCon battery according to claim 14, characterized in that The diameter of the glue dots is 0.5-1 mm.

16. The TOPCon battery according to claim 12, characterized in that The distance between the glue points is 5-80 mm.

17. The TOPCon battery according to claim 16, characterized in that The distance between the glue points is 8-60 mm.

18. The TOPCon battery according to claim 17, characterized in that The distance between the glue points is 10-50 mm.

19. The TOPCon battery according to claim 1, characterized in that The adhesive application surface of the structural adhesive is the back side of the battery cell.

20. The TOPCon battery according to claim 1, characterized in that The structural adhesive is an adhesive tape, and the adhesive tape is arranged between the fine grids and along the length direction of the fine grids.

21. The TOPCon battery according to claim 20, characterized in that The height of the tape is 10-80 μm.

22. The TOPCon battery according to claim 21, characterized in that The height of the tape is 15-65 μm.

23. The TOPCon battery according to claim 22, characterized in that The height of the tape is 20-50 μm.

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