Stacked gate battery

Abstract

According to the stacked gate battery provided by the utility model, a reinforcing material (structural adhesive) with high adhesive force is introduced and is applied to the conductive wires in flexible modes of printing, spraying or ink-jet printing and the like, and tiny gaps between the conductive wires and the silicon wafers are quickly filled by utilizing the high flowability of the structural adhesive. The structure can ensure that the connection force between the conductive wire and the current collection layer is enhanced, so that the service life of the assembly is prolonged in the subsequent power generation process; the structure of the utility model is also beneficial to post-processing of the battery, including but not limited to reducing the risks of conductive wire falling, short circuit and the like which may occur during string formation, lamination and lamination in the battery transfer, test and assembly manufacturing processes; and the battery loss in the assembly manufacturing process is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaic technology, in particular to a superimposed grid cell. BACKGROUND

[0002] The photovoltaic solar cell technology has undergone multiple iterations from polycrystalline to single crystal PERC, and then to N-type Topcon over the years, with the core goal always focusing on efficiency and cost reduction. In recent years, superimposed grid cell technology, as a new type of high-efficiency solar cell technology, is emerging.

[0003] The superimposed grid technology adopts a double-layer structure design, that is, a conductive seed layer (usually formed using a small amount of silver paste) is first prepared on the surface of the cell to collect the current on the surface of the cell, and then a very fine conductive wire (such as copper wire or a very fine triangular conductive wire with ultra-high surface reflectivity) is placed on the seed layer. This double-layer structure enables current to be more effectively extracted from the cell and form a series connection with another cell.

[0004] The conductive seed layer is in contact with the cell to extract current from the cell and form good contact with the upper conductive wire. The upper conductive wire is responsible for series connection with another cell, thereby achieving efficient transmission of current.

[0005] This technology significantly reduces the amount of silver paste used by changing the cell structure, thereby greatly reducing the cost of solar cells. However, the superimposed grid cell technology does not design a traditional main grid, but directly realizes welding on a very thin seed layer, which results in low welding tension and poses a serious challenge to the subsequent reliability of the cell.

[0006] However, in the prior art, the superimposed grid cell forms a current path by printing a very thin seed layer on the surface of the cell and laying a triangular conductive wire on it. However, since the width of the conductive wire is greater than that of the seed layer, and the contact area between them is limited, the tension between the conductive wire and the seed layer is small, and peeling off easily affects the reliability and service life of the cell. From the published patents, patent CN 221201190 U enhances the welding force by adding a solder pad on the conductive wire, and patent CN 118431319 A protects the packaging method of the cell by laying glue on the front surface of the cell, but does not enhance the adhesion of the conductive wire. The conductive wire is more likely to fall off during long-term operation of the cell or under the influence of external environment (such as temperature fluctuations, mechanical vibrations, etc.). Practical new type

[0007] To solve at least one problem raised in the above technical background, the present application provides a superimposed grid cell, comprising:

[0008] A battery piece substrate, one side of which is provided with a passivation layer, the passivation layer comprising a silicon nitride layer (SINx), and an upper surface of the passivation layer is provided with a grid structure,

[0009] The grid structure comprises:

[0010] A seed layer is laid on the passivation layer;

[0011] A conductive wire with solder on the surface is connected to the upper surface of the seed layer through the solder;

[0012] A structural adhesive is filled in the gap formed by the conductive wire, the seed layer, and the passivation layer, and is used to reinforce the connection between the conductive wire and the seed layer and between the conductive wire and the passivation layer.

[0013] In a preferred embodiment, the material of the seed layer printing is selected from one or a combination of silver and copper.

[0014] Preferably, the material of the seed layer printing is selected from silver and copper, and the printing width of the copper accounts for 60-99%, preferably 70-98%, and more preferably 75-95% of the printing width of the seed layer.

[0015] In a preferred embodiment, the printing width of the seed layer is 5-40μm, preferably 10-30μm, and more preferably 15-20μm.

[0016] In a preferred embodiment, the printing thickness of the seed layer is 1-10μm, preferably 2-8μm, and more preferably 3-5μm.

[0017] In a preferred embodiment, the cross section of the conductive wire is circular or triangular.

[0018] Preferably, the single side length of the triangular conductive wire is 50-350μm, preferably 100-300μm, and more preferably 150-250μm.

[0019] In a preferred embodiment, the height of the gap is 1-10μm, preferably 2-8μm, and more preferably 3-5μm.

[0020] In a preferred embodiment, the structural adhesive is coated in the gap, and the coating method includes one or a combination of dispensing, printing, spraying, and coating.

[0021] In a preferred embodiment, the structural adhesive is colorless and transparent, and can transmit light for the battery piece to absorb light energy.

[0022] Preferably, after the coating is completed, the structural adhesive is cured by ultraviolet light irradiation.

[0023] More preferably, the wavelength of the ultraviolet light is 100-500 nm, preferably 150-450 nm, and more preferably 190-405 nm.

[0024] More preferably, the curing time is 1-60 s, preferably 2-30 s, and more preferably 3-10 s.

[0025] More preferably, the amount of the structural adhesive applied to the gap on both sides of the monolithic cell is 2-80 mg, preferably 3-60 mg, and more preferably 10-50 mg.

[0026] More preferably, the structural adhesive partially wraps the conductive wire and can sufficiently fill the gap.

[0027] More preferably, the structural adhesive only completely fills the gap and does not wrap the conductive wire.

[0028] Preferably, the viscosity of the structural adhesive is 60 cps-1500 cps@25℃, preferably 80 cps-1200 cps@25℃, and more preferably 100 cps-1000 cps@25℃.

[0029] Preferably, the thixotropy index of the structural adhesive is 0.1-4, preferably 0.2-3, and more preferably 0.3-2.

[0030] Preferably, the structural adhesive further contains conductive particles, such as silver particles, copper particles, gold particles, and nickel particles.

[0031] In a preferred embodiment, the method for applying the structural adhesive to the interdigital cell includes the following steps:

[0032] Providing a structural adhesive;

[0033] Applying the structural adhesive along the two waist sides of the conductive wire, which can be applied by dispensing, spraying, printing, or coating;

[0034] The glue with a preset viscosity flows along the surface of the conductive wire and enters the gap between the conductive wire and the cell;

[0035] Irradiation by ultraviolet light with a preset wavelength to cure the structural adhesive; the cured glue can firmly fix the conductive wire on the silicon wafer, improving the reliability of the interdigital cell.

[0036] In the present application, the thickness of the seed layer needs to be accurately controlled to avoid problems such as increased difficulty in electroplating copper due to excessive thickness or poor current-carrying performance due to excessive thinness.

[0037] In the present application, the thixotropic index reflects the viscosity of the structural adhesive, referred to as TI value (Thixotropic index), which refers to the ratio (unitless) between the low-speed viscosity and the high-speed viscosity of non-Newtonian materials. The thixotropic index is obtained by dividing the test speed (the test environment is room temperature), which is usually the viscosity value obtained by testing at 0.5 rpm and 5 rpm (or the data obtained by dividing the speed by 10 times), which is not a standard and can be understood as a reference value.

[0038] In the present application, the gap formed by the conductive wire, the seed layer and the passivation layer is divided into two waist sides. The gap is caused by the seed layer being higher than the surface of the battery piece.

[0039] Compared with the prior art, the utility model has the following beneficial effects:

[0040] The utility model discloses a kind of interdigital cell, by introducing high adhesion reinforcing material (structural adhesive), to be applied to conductive wire in flexible mode such as printing, spraying or inkjet printing, utilize the high flowability of structural adhesive to fill the small gap between conductive wire and silicon piece quickly.The structure can ensure the connecting force of reinforcing conductive wire and current collection layer, so that the life of assembly is extended in subsequent power generation process.And when there is base metal paste in seed layer, through the design of this structure, can protect base metal part from being oxidized, so as to realize the use of base metal paste (for example, copper paste) in seed layer in interdigital structure.The structure of the utility model is also beneficial to later treatment of battery, including but not limited to reducing the risk that conductive wire may fall off and short circuit when battery is transferred, tested and assembled in the process of group string, lamination, laminating;Reduce battery loss in the process of assembly.

[0041] In addition, the utility model can also be aimed at other battery with weak connection between conductive wire and current collection layer (such as multi-main grid battery, laminated battery, micro battery) to reinforce the connection between conductive wire and current collection layer, which can effectively strengthen the connection between current collection layer and conductive wire, solve the problem that conductive wire is easy to break open and desoldering in these battery structures due to small width and low height of current collection layer, small contact area between current collection layer and conductive wire, and weak connection. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or prior art, the following will briefly introduce the drawings needed to be used in embodiment or prior art description, and obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0043] Figure 1 Figure 1 is a structural schematic diagram of a stacked gate battery according to an embodiment of the present application.

[0044] The reference signs are explained as follows:

[0045] 1, solder; 2, conductive wire; 3, structural adhesive; 4, passivation layer; 5, battery piece substrate; 6, seed layer. DETAILED DESCRIPTION

[0046] The present application provides a stacked gate battery, in order to make the purpose, technical scheme and effect of the present application more clear and definite, the present application is further explained in detail below with reference to the drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the content of the present application, and are not used to limit the content of the present application.

[0047] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0048] Embodiment 1:

[0049] The present embodiment provides a stacked gate battery, comprising:

[0050] The battery piece substrate 5 is the basic support of the battery, and a passivation layer 4 is provided thereon. The passivation layer 4 is designed to protect the battery piece substrate 5 and improve the photoelectric conversion efficiency. The passivation layer 4 comprises a Poly layer, an aluminum oxide layer and a silicon nitride layer from top to bottom. The passivation layer 4 is provided with a stacked gate structure, wherein the stacked gate structure comprises:

[0051] The seed layer 6 is laid on the passivation layer 4 and is made of silver paste printing, mainly as a conductive substrate to provide uniform current distribution for subsequent electroplating or soldering process. The deposition of the seed layer 6 needs to have good hole filling ability and side wall covering ability to ensure good contact with the subsequent conductive structure.

[0052] The conductive wire 2 is designed as a right triangle with a single side concave section to increase the contact area with the seed layer 6 and improve the connection strength. The surface is provided with solder 1, which is welded and connected with the upper surface of the seed layer 6. The single side length of the triangular conductive wire is preferably 150-250 μm to balance the conductive performance and material cost.

[0053] Structural glue 3: filled in the tiny gap formed by the conductive wire 2, the seed layer 6 and the passivation layer 4, plays a role in reinforcing the connection of the conductive wire 2. The structural glue 3 is colorless and transparent, and does not affect the absorption of light energy by the battery piece substrate 5. The viscosity of the structural glue 3 is controlled at 100cps-1000cps@25℃, to ensure that it can effectively flow to fill the gap, and can maintain sufficient adhesion after solidification.

[0054] The sizing method and solidification of the present embodiment include the following steps:

[0055] The structural glue 3 is printed along the two waist sides of the conductive wire 2, and naturally fills the gap by its flowability.

[0056] By irradiating with a preset wavelength of ultraviolet light (such as 190-405nm), the structural glue is solidified in a very short time (such as 3-10s), firmly fixing the conductive wire on the passivation layer 4.

[0057] Example 2:

[0058] The present embodiment also provides a stacked grid battery, which includes:

[0059] The battery piece substrate 5 serves as the basic support of the battery, and is provided with a passivation layer 4, which is designed to protect the battery piece substrate 5 and improve the photoelectric conversion efficiency. The passivation layer 4 has an aluminum oxide layer and a silicon nitride layer from top to bottom. The passivation layer 4 is provided with a stacked grid structure, wherein the stacked grid structure includes:

[0060] The seed layer 6 is laid on the passivation layer 4 and is made of printed copper paste and silver paste, mainly serving as a conductive base to provide uniform current distribution for subsequent electroplating or soldering processes. The printed width of the copper paste is 18μm, and silver paste is printed on both sides of the copper paste, with a printed width of 1μm on both sides. The overall printed width of the seed layer is 20μm. The deposition of the seed layer 6 needs to have good hole-filling ability and side wall coverage ability to ensure good contact with the subsequent conductive structure.

[0061] The conductive wire 2 has a circular cross-section, and its surface is provided with solder 1 for welding connection with the upper surface of the seed layer 6. The cross-sectional diameter of the circular conductive wire is preferably 150-250μm to balance the conductive performance and material cost.

[0062] The structural glue 3 is filled in the tiny gap formed by the conductive wire 2, the seed layer 6 and the passivation layer 4, plays a role in reinforcing the connection of the conductive wire 2. The structural glue 3 is colorless and transparent, and does not affect the absorption of light energy by the battery piece substrate 5. The viscosity of the structural glue 3 is controlled at 100cps-1000cps@25℃, to ensure that it can effectively flow to fill the gap, and can maintain sufficient adhesion after solidification. Silver conductive particles are added to the structural glue 3 to enhance the conductive performance.

[0063] The sizing method and curing steps of the embodiment include:

[0064] The structural adhesive 3 is sprayed along the two sides of the conductive wire 2, and naturally fills the gap by its fluidity.

[0065] The structural adhesive is cured in a very short time (such as 3-10s) by irradiation of ultraviolet light of a preset wavelength (such as 190-405nm), and the conductive wire is firmly fixed on the silicon wafer.

[0066] In summary, the interdigital battery provided by the present application significantly improves the connection strength between the conductive wire and the seed layer and the passivation layer by introducing the structural adhesive reinforcement technology, thereby improving the reliability and service life of the battery.

[0067] The specific embodiments of the present application are described in detail above, but the present application is not limited to the specific embodiments described above. Any equivalent modifications and substitutions of the present application made by those skilled in the art are also within the scope of the present application. Therefore, equivalent transformations and modifications made without departing from the spirit and scope of the present application should be included in the scope of the present application.

Claims

1. A stacked gate cell, characterized by, The utility model relates to a monolithic battery and a manufacturing method thereof, and relates to the technical field of monolithic batteries. The utility model discloses a battery piece base body, one side of the battery piece base body is equipped with a passivation layer, a stacked grid structure is arranged on the passivation layer, and the stacked grid structure comprises: A seed layer is laid on the passivation layer. A conductive wire is provided with solder tin on the surface, and the conductive wire is connected with the upper surface of the seed layer through solder tin. Structural glue is filled in the gap formed by the conductive wire, the seed layer and the passivation layer, and is used for reinforcing the connection between the conductive wire and the seed layer and the connection between the conductive wire and the passivation layer.

2. The stacked gate cell of claim 1, wherein, The seed layer is composed of a copper printing layer in the middle and silver printing layers on both sides of the copper printing layer.

3. The stacked gate cell of claim 1, wherein, The printing width of copper accounts for 75-95% of the printing width of the seed layer.

4. The stacked gate cell of claim 1, wherein, The cross section of the conductive wire is triangular or circular.

5. The stacked gate cell of claim 1 wherein, The cross section of the conductive wire is an equilateral triangle, and the length of a single side of the equilateral triangle is 150-250 mu m.

6. The stacked gate cell of claim 1, wherein, The height of the gap is 3-5 mu m. The structural glue is colorless and transparent, can transmit light, and can be used for monolithic battery to absorb light energy.

7. The stacked grid cell of claim 6, wherein, After the coating is completed, the structural glue is cured by ultraviolet light irradiation. The wavelength of the ultraviolet light is 190-405 nm.

8. The stacked cell of claim 1, wherein, The curing time is 3-10 s.

9. The stacked cell of claim 1, wherein, The glue application amount of the gap on both sides of the monolithic battery is 10-50 mg. The viscosity of the structural glue is 100 cps-1000 cps at 25 DEG C.

10. The stacked cell of claim 1, wherein, The thixotropy index of the structural glue is 0.3-2. The structural glue also contains conductive particles.

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