A shingled battery and low-fold back film and metallization process

Abstract

The present invention discloses a shingled battery, a low-fold back film and a metallization process, which includes a silicon oxynitride layer, a first silicon nitride layer, a second silicon nitride layer, and a third silicon nitride layer sequentially arranged from inside to outside. S i H4 and NH3 are introduced into the reaction furnace, and the reaction time is 190 - 210 s to form a first silicon nitride layer with a silicon-nitrogen ratio of 1:4.6 - 4.9. S i H4 and NH3 are introduced into the reaction furnace, and the reaction time is 140 - 160 s to form a second silicon nitride layer with a silicon-nitrogen ratio of 1:8.9 - 9.1. S i H4 and NH3 are introduced into the reaction furnace, and the reaction time is 90 - 110 s to form a third silicon nitride layer with a silicon-nitrogen ratio of 1:11.7 - 11.9. The present invention can not only reduce the aperture of laser grooving, reduce the reaction between the silicon substrate and aluminum, but also improve the stability of SiNx, reduce its chemical reaction with the aluminum paste, thereby reducing the line resistance and improving the efficiency of the shingled battery.

Description

Technical Field

[0001] The invention relates to a low-folding-wattage battery back film and a manufacturing process, belonging to the technical field of shingled batteries. Background Art

[0002] Shingled cells increase their efficiency by stacking multiple thin layers on a crystalline silicon cell, allowing light to pass through multiple cell layers, thereby utilizing more solar energy.

[0003] Chinese patent CN114914322A discloses an N-type monocrystalline silicon substrate shingled solar cell and its manufacturing method. It includes the following steps: taking 6-10 parts by weight of carbon, 12-15 parts by weight of hydrogen chloride, 6-10 parts by weight of silicon dioxide, 1-2 parts by weight of a diffusant, and 6-8 parts by weight of a mixture of boron, nitrogen and phosphorus; heating silicon dioxide and adding carbon to reduce silicon to obtain crude silicon, adding hydrogen chloride to purify the crude silicon to obtain refined silicon; depositing refined silicon to obtain elemental silicon, melting the elemental silicon, adding a diffusant to change the light transmittance, and adding boron, nitrogen and phosphorus to cool and solidify the elemental silicon to form high-purity monocrystalline silicon containing boron, nitrogen and phosphorus impurities; slicing the monocrystalline silicon, cutting the monocrystalline silicon into multiple square pieces, and stacking and arranging the multiple square pieces, welding them into strings, and laminating them to form shingles. The patent doped phosphorus with a predetermined amount of boron and nitrogen, so that the lattice distortion caused by phosphorus can be reliably compensated by boron, thereby avoiding dislocation when forming an epitaxial layer on the surface of a semiconductor substrate obtained from the produced ingot. By adding an organic silicon light diffuser, after adding it to the single crystal silicon, the organic silicon light diffuser will be evenly dispersed in the matrix as a fine transparent glass sphere. Through the difference in refractive index with different substrates, the light source will be refracted in a penetrating manner, changing the path of light, achieving the purpose of uniform light and light transmission, and the combination of silicon dioxide and organic silicon light diffuser makes part of the organic silicon light diffuser form silicon dioxide when calcium dioxide is reduced, thereby increasing the purity of the single crystal silicon.

[0004] Chinese patent CN 110350051 A discloses a nitrogen-containing crystalline silicon shingled bifacial solar cell and its preparation method, which includes a first silicon nitride anti-reflection layer, a p-type doping layer, an n-type silicon substrate layer, a tantalum nitride back passivation layer, and a second silicon nitride anti-reflection layer arranged from top to bottom, and a metal grid electrode layer is also arranged on the upper surface of the first silicon nitride anti-reflection layer and the lower surface of the second silicon nitride anti-reflection layer. The back of the solar cell adopts a tantalum nitride back passivation layer and a second silicon nitride anti-reflection layer, which reduces the back recombination rate of the solar cell and the reflectivity of the incident light on the back, improves the efficiency of the back cell and the short-circuit current of the back cell, and the bifaciality of the solar cell. The tantalum nitride back passivation layer not only has the ability to selectively transmit electrons, but also can reduce the contact resistance of the back electrode printing.

[0005] From the above, it can be seen that the refractive index of the back film affects the efficiency of the shingled cell, so how to reduce the refractive index of the back film of the shingled cell becomes the key. Summary of the invention

[0006] Purpose of the invention: In order to reduce the refractive index of the shingled cell back film, the present invention provides a low-folding shingle cell back film and a manufacturing process.

[0007] Technical solution: To achieve the above purpose, the technical solution adopted by the present invention is:

[0008] A low-folding-wattage battery back film comprises a silicon oxynitride layer, a first silicon nitrogen layer, a second silicon nitrogen layer, and a third silicon nitrogen layer, which are arranged in sequence from the inside to the outside, wherein the silicon nitrogen ratio of the first silicon nitrogen layer is 1:4.6-4.9, the silicon nitrogen ratio of the second silicon nitrogen layer is 1:8.9-9.1, and the silicon nitrogen ratio of the third silicon nitrogen layer is 1:11.7-11.9.

[0009] Preferably, the silicon-nitrogen ratio of the silicon oxynitride layer is 1:6.1-6.3.

[0010] A metallization process for a low folding wattage battery back film comprises the following steps:

[0011] Step 1: Place the back film of the shingled battery to be treated into the first reaction furnace, introduce SiH4, NH3, and N2O into the first reaction furnace, and react for 130-150 seconds to generate a silicon oxynitride layer on the back film of the shingled battery to be treated.

[0012] Step 2: Place the back film of the shingled cell to be treated with the silicon nitride oxide layer into the second reaction furnace, introduce SiH4 and NH3 into the second reaction furnace, and react for 190-210s to generate a first silicon nitrogen layer on the silicon nitride oxide layer. The silicon nitrogen ratio of the first silicon nitrogen layer is 1:4.6-4.9.

[0013] Step three, the back film of the shingled cell to be treated with the first silicon nitrogen layer is placed into the third reaction furnace, SiH4 and NH3 are introduced into the third reaction furnace, the reaction time is 140-160s, and the second silicon nitrogen layer is generated on the first silicon nitrogen layer. The silicon nitrogen ratio of the second silicon nitrogen layer is 1:8.9-9.1.

[0014] Step four, placing the back film of the shingled cell to be treated with the second silicon nitrogen layer into the fourth reaction furnace, introducing SiH4 and NH3 into the fourth reaction furnace, the reaction time is 90-110s, and a third silicon nitrogen layer is generated on the second silicon nitrogen layer. The silicon nitrogen ratio of the third silicon nitrogen layer is 1:11.7-11.9.

[0015] A shingled battery comprises a front film, a silicon substrate layer and the above-mentioned low-folding-watt battery back film, wherein the front film is arranged on the front side of the silicon substrate layer, and the low-folding-watt battery back film is arranged on the back side of the silicon substrate layer.

[0016] The present invention adjusts the silicon nitrogen content of each silicon nitrogen layer to reduce the refractive index of SiNx material (silicon nitride material), so that less silicon is exposed in the same laser grooving process, and the aperture of the laser grooving is reduced. At the same time, the stability of SiNx is improved, so that its reaction with aluminum paste is weaker, and the overall line resistance increase is smaller, thereby improving the efficiency of the shingled cell.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention can not only reduce the aperture of laser grooving and reduce the reaction between the silicon substrate and aluminum, but also improve the stability of SiNx and reduce its chemical reaction with aluminum paste, thereby reducing line resistance and improving the efficiency of shingled cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the mechanism of high line resistance of solar cells. Figure 1 A in the figure represents the physical and chemical reaction between Al and silicon base, which will cause a large amount of silicon elements to enter the aluminum gate line, resulting in an increase in line resistance. Figure 1 B in the figure represents the Al paste, which will also undergo a certain chemical reaction with the silicon nitride film layer on the back during the high-temperature sintering process, causing the properties of the aluminum paste to change. At the same time, impurity elements will enter the aluminum paste, causing the line resistance to be higher.

[0020] Figure 2 Schematic diagram showing that the reduction in refractive index makes the line resistance increase caused by laser grooving smaller. Figure 2 A is the decrease in the refractive index of SiNx material, which means a decrease in the extinction coefficient k.

[0021] Figure 3 SY refers to the metallization process of the low-folding-watt battery back film, and the production line refers to the manufacturing process of the existing shingled battery back film.

[0022] Figure 4 The resistance test results of the aluminum grid lines on the back side of the shingled battery back films prepared in Example 1 and Example 4 are shown.

[0023] Figure 5 The first is the experimental data of the front and back shingled battery back film of Example 1.

[0024] Figure 6 The second experimental data of the front and back shingled battery back film of Example 1.

[0025] Figure 7 Schematic diagram of laser grooving comparison of the shingled cell back films prepared in Example 1 and Example 4. Figure 7Figure A in the middle is a schematic diagram of laser grooving of a shingled battery back film obtained by the metallization process of a low-folding-watt battery back film in Example 1. Figure 7 Figure B in the middle is a schematic diagram of laser grooving of a shingled battery back film produced by the manufacturing process of the existing shingled battery back film in Example 4.

[0026] Figure 8 The test results of the resistance of the aluminum grid lines on the back side of the shingled battery back films prepared in Example 1 and Example 4 are shown. DETAILED DESCRIPTION

[0027] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0028] Example 1

[0029] A low-folding-wattage battery back film comprises a silicon oxynitride layer, a first silicon nitrogen layer, a second silicon nitrogen layer, and a third silicon nitrogen layer, which are arranged in sequence from the inside to the outside, wherein the silicon oxynitride layer has a silicon-nitrogen ratio of 1:6.1-6.3, the first silicon nitrogen layer has a silicon-nitrogen ratio of 1:4.6-4.9, the second silicon nitrogen layer has a silicon-nitrogen ratio of 1:8.9-9.1, and the third silicon nitrogen layer has a silicon-nitrogen ratio of 1:11.7-11.9.

[0030] A shingled battery comprises a front film, a silicon substrate layer and the above-mentioned low-folding-watt battery back film, wherein the front film is arranged on the front side of the silicon substrate layer, and the low-folding-watt battery back film is arranged on the back side of the silicon substrate layer.

[0031] A metallization process for a low folding wattage battery back film comprises the following steps:

[0032] Step 1: Place the back film of the shingled battery to be treated into the first reaction furnace, introduce SiH4, NH3 and N2O into the first reaction furnace, and the reaction time is 140s. The flow rate of SiH4 introduced into the first reaction furnace is 1070sccm, the flow rate of NH3 is 6700sccm, and the flow rate of N2O is 4700sccm, and a silicon oxynitride layer is generated on the back film of the shingled battery to be treated. Sccm represents standard milliliters per minute.

[0033] Step 2: Place the back film of the shingled cell to be treated with the silicon nitride oxide layer into the second reaction furnace, introduce SiH4 and NH3 into the second reaction furnace, the reaction time is 200s, the SiH4 flow rate is 2200sccm, and the NH3 flow rate is 10300sccm, and the first silicon nitrogen layer is generated on the silicon nitride oxide layer.

[0034] Step three, place the back film of the shingled cell to be treated with the first silicon nitrogen layer into the third reaction furnace, introduce SiH4 and NH3 into the third reaction furnace, the reaction time is 150s, the SiH4 flow rate is 1360sccm, the NH3 flow rate is 12200sccm, and the second silicon nitrogen layer is generated on the first silicon nitrogen layer.

[0035] Step four, placing the back film of the shingled battery to be treated with the second silicon nitrogen layer into the fourth reactor, introducing SiH4 and NH3 into the fourth reactor, the reaction time is 100s, the SiH4 flow rate is 1300sccm, the NH3 flow rate is 15350sccm, and the third silicon nitrogen layer is generated on the second silicon nitrogen layer. The silicon nitrogen ratio of the third silicon nitrogen layer is 1:11.7-11.9.

[0036] The simple calculation model of the grid line resistance on the back side (back film) of a 210 conventional battery is as follows:

[0037] The secondary grid between two adjacent main grids is of parallel type. If the resistance per unit length of the secondary grid is assumed to be R, then:

[0038] The gate line resistance between the two main grids is:

[0039] All main grids are in parallel structure, so:

[0040] The total gate line resistance on the back is: .

[0041] The simple calculation model of the back grid line resistance of the shingled cell is as follows:

[0042] The secondary grid between two adjacent main grids is of parallel type. If the resistance per unit length of the secondary grid is assumed to be R, then:

[0043] The gate line resistance between the two main grids is:

[0044] All main grids are in parallel structure, so:

[0045] The total gate line resistance on the back is: .

[0046] The calculation model of the back grid line resistance of the shingled battery is the same as that of the 210 conventional battery, and there is a large error. However, the data calculated by the two models are different in order of magnitude, which still shows that there is a large difference in the grid line resistance between the two. In general, the grid line resistance of the shingled battery is larger.

[0047] In the volt-ampere characteristic curve of a solar cell, the ratio of the area of ​​the inner rectangle to the area of ​​the outer rectangle is called the fill factor. As the series resistance of the battery increases, the fill factor will drop significantly. The series resistance mainly consists of three parts: line resistance, contact resistance, and the resistance of the battery itself. Of these three resistances, only line resistance and contact resistance are easy to control. For conventional graphic batteries, their line resistance is already small enough, so it is more cost-effective to continue to reduce the line resistance to improve efficiency. However, since the line resistance of shingled batteries is still relatively high, there is still room for improvement.

[0048] like Figure 1 As shown, Figure 1 As shown in Figure A, the physical and chemical reaction between Al and silicon base will cause a large amount of silicon elements to enter the aluminum gate line, resulting in an increase in line resistance. Figure 1 As shown in Figure B, during the high-temperature sintering process, the Al paste will also undergo a certain chemical reaction with the silicon nitride film layer on the back, causing the properties of the aluminum paste to change. At the same time, impurity elements will enter the aluminum paste, causing the line resistance to be high.

[0049] Si3N4 is an inorganic material with excellent high-temperature chemical stability. It is used to make thermocouple tubes, rocket nozzles and crucibles used to melt metals. Its refractive index is 1.9. The silicon nitride on the back of the solar cell is a material in which Si atoms are inserted into the lattice gap of Si3N4. Its chemical formula is SiN x Generally speaking, the more silicon atoms are inserted, the higher the refractive index of the silicon nitride film, with the ultimate limit being 4 for pure silicon.

[0050] This means that if we can lower the refractive index of silicon nitride material, we can improve the stability of SiNx, thereby reducing its chemical reaction with aluminum paste and reducing line resistance.

[0051] like Figure 2 As shown in Figure A, the reduction in the refractive index of the SiNx material means a reduction in the extinction coefficient k. That is to say, in the same laser grooving process, the silicon of the wafer with low fold back film is less exposed, and the reaction with the aluminum paste is weaker, so the line resistance increase caused by this process is smaller.

[0052] In combination with the above, it can be confirmed that the low-low folding wattage battery back film obtained by the present invention can reduce the aperture of the laser grooving under the same laser grooving conditions, reduce the reaction between the silicon substrate and aluminum, and thus reduce the line resistance; it can also improve the stability of SiNx and reduce its chemical reaction with aluminum paste, thereby reducing the line resistance.

[0053] Example 2

[0054] The difference between this embodiment and embodiment 1 is that:

[0055] The reaction time in the first reaction furnace is 150s, and the flow rate of SiH4, NH3 and N2O in the first reaction furnace is 970sccm, 6600sccm and 4600sccm, respectively.

[0056] In the second reaction furnace, the reaction time is 210 s, the SiH4 flow rate is 2100 sccm, and the NH3 flow rate is 10200 sccm.

[0057] In the third reaction furnace, the reaction time is 160 s, the SiH4 flow rate is 1260 sccm, and the NH3 flow rate is 12100 sccm.

[0058] In the fourth reaction furnace, the reaction time is 110 s, the SiH4 flow rate is 1200 sccm, and the NH3 flow rate is 15250 sccm.

[0059] Example 3

[0060] The difference between this embodiment and embodiments 1 and 2 is that:

[0061] The reaction time in the first reaction furnace is 130s, the flow rate of SiH4 introduced into the first reaction furnace is 1170, the flow rate of NH3 is 6800sccm, and the flow rate of N2O is 4800sccm.

[0062] In the second reaction furnace, the reaction time is 190 s, the SiH4 flow rate is 2300 sccm, and the NH3 flow rate is 10400 sccm.

[0063] In the third reaction furnace, the reaction time is 140 s, the SiH4 flow rate is 1460 sccm, and the NH3 flow rate is 12300 sccm.

[0064] In the fourth reaction furnace, the reaction time is 90 s, the SiH4 flow rate is 1400 sccm, and the NH3 flow rate is 15450 sccm.

[0065] Example 4

[0066] This embodiment is a manufacturing process of an existing shingled battery back film, and its related steps and parameters are shown in Tables 1 and 2 below:

[0067] Table 1 Manufacturing process steps and parameters of existing shingled battery back film

[0068]

[0069] In Table 1, the parameters are explained as follows: When preparing the back film layer, we use a tube furnace. Due to the difference in heat dissipation capacity, the temperature of different parts of the furnace tube is different. For easy management, the furnace tube is divided into 6 areas from front to back and numbered as 1, 2, 3, 4, 5, 6. The temperature x here refers to the set temperature of the area numbered x in this step.

[0070] The coating process requires the application of an electric field to plasmatize the gas, which simply means that electricity is required. However, it is impossible to keep the electricity on during the entire coating process. Generally, the electricity is on for a while, then off for a while, and then on again, and so on. The pulse on here refers to the time (s) of the power-on step in the process, and the pulse off refers to the time (s) of the power-off step.

[0071] Table 2 Manufacturing process steps and parameters of existing shingled battery back film

[0072]

[0073] In Table 2, the parameters are described as follows: N2 refers to nitrogen flow rate, SiH4 refers to silane flow rate, NH3 refers to ammonia flow rate, N2O refers to nitrous oxide flow rate, pressure refers to the gas pressure in the tube, power 1 refers to coating power, current 1 refers to the average current of coating alternating current, current 1 deviation refers to the fluctuation range of current, auxiliary heating time refers to the time for heating the silicon wafer, and auxiliary heating temperature refers to the temperature that the silicon wafer needs to reach before coating.

[0074] It can be seen from Table 1 and Table 2 that the manufacturing process of the existing shingled battery back film is different from that of Example 1 in that:

[0075] The reaction time in the first reaction furnace is 115s, the flow rate of SiH4 introduced into the first reaction furnace is 1070sccm, the flow rate of NH3 is 6700sccm, and the flow rate of N2O is 4700sccm.

[0076] In the second reaction furnace, the reaction time is 200 s, the SiH4 flow rate is 2500 sccm, and the NH3 flow rate is 10000 sccm.

[0077] In the third reaction furnace, the reaction time is 170 s, the SiH4 flow rate is 1560 sccm, and the NH3 flow rate is 12000 sccm.

[0078] In the fourth reaction furnace, the reaction time is 75 s, the SiH4 flow rate is 1500 sccm, and the NH3 flow rate is 15150 sccm.

[0079] like Figure 3The figure shows the film thickness and refractive index data of the shingled battery back film obtained in Example 1 and Example 4. It can be seen from the figure that the average film thickness obtained by the metallization process of the low-folding-watt battery back film is 85.89, and the average refractive index is 2.12. The average film thickness obtained by the existing shingled battery back film manufacturing process is 86.19, and the average refractive index is 2.19. The average film thickness obtained by the metallization process of the low-folding-watt battery back film is 0.3 less than the average film thickness obtained by the existing shingled battery back film manufacturing process, and the refractive index is 0.07 less.

[0080] like Figure 4 As shown, the back aluminum grid line resistance test results of the shingled battery back film prepared in Example 1 and Example 4. It can be seen from the figure that the back aluminum grid line resistance of the shingled battery back film prepared in Example 1 is lower than the back aluminum grid line resistance of the shingled battery back film prepared in Example 4.

[0081] like Figure 5 , 6 As shown in the figure, it is the experimental data of the shingled battery back film before and after Example 1. It can be seen from the figure that the efficiency of the back film obtained by the metallization process of the low-folding-watt battery back film of the present invention is higher than the efficiency of the back film before the metallization process of the low-folding-watt battery back film is performed, which is mainly reflected in the FF being 0.06% higher.

[0082] like Figure 7 As shown, the average aperture value of the laser grooved back film of the shingled battery prepared in Example 1 is 2.84 smaller than the average aperture value of the laser grooved back film of the shingled battery prepared in Example 4, and the aperture spacing of the laser grooved back film of the shingled battery prepared in Example 1 is 1.185 larger than the aperture spacing of the laser grooved back film of the shingled battery prepared in Example 4.

[0083] like Figure 8 As shown, the test results of the back aluminum grid line resistance of the shingled battery back film prepared in Example 1 and Example 4 are shown. From the T test results, it can be seen that 9.19414E-06<0.05, indicating that the mean values ​​of the back aluminum grid line resistance of the shingled battery back film prepared in Example 1 and Example 4 are significantly different. From the F test results, it can be seen that 0.248173204<0.05, indicating that the mean values ​​of the back aluminum grid line resistance of the shingled battery back film prepared in Example 1 and Example 4 are significantly different. Figure 7 It can be seen from the inspection data in that the metallization process of the low-folding watt battery back film of the present invention is significantly different from the shingled battery back film produced by the manufacturing process of the existing shingled battery back film.

[0084] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A metallization process for a low folding watt battery back film, characterized in that: The following steps are involved: Step 1: Place the back film of the shingled battery to be treated into the first reaction furnace, introduce SiH4, NH3, and N2O into the first reaction furnace, and react for 130-150 seconds to generate a silicon oxynitride layer on the back film of the shingled battery to be treated; Step 2: Place the back film of the shingled cell to be treated with the silicon oxynitride layer in a second reaction furnace, introduce SiH4 and NH3 into the second reaction furnace, react for 190-210 seconds, and generate a first silicon nitrogen layer on the silicon oxynitride layer, wherein the silicon nitrogen ratio of the first silicon nitrogen layer is 1:4.6-4.9; Step 3, placing the untreated shingled cell back film with the first silicon nitrogen layer into a third reaction furnace, introducing SiH4 and NH3 into the third reaction furnace, reacting for 140-160 seconds, and generating a second silicon nitrogen layer on the first silicon nitrogen layer, wherein the silicon nitrogen ratio of the second silicon nitrogen layer is 1:8.9-9.1; Step four, placing the back film of the shingled cell to be treated with the second silicon nitrogen layer into the fourth reaction furnace, introducing SiH4 and NH3 into the fourth reaction furnace, the reaction time is 90-110s, and a third silicon nitrogen layer is generated on the second silicon nitrogen layer. The silicon nitrogen ratio of the third silicon nitrogen layer is 1:11.7-11.

9.

2. The metallization process of the low folding watt battery back film according to claim 1, characterized in that: In the first reactor, the SiH4 flow rate is 970-1170sccm, the NH3 flow rate is 6600-6800sccm, and the N2O flow rate is 4600-4800sccm.

3. The metallization process of the low folding watt battery back film according to claim 2, characterized in that: The SiH4 flow rate in the second reaction furnace is 2100-2300sccm, and the NH3 flow rate is 10200-10400sccm.

4. The metallization process of the low folding watt battery back film according to claim 3, characterized in that: The SiH4 flow rate in the third reactor is 1260-1460sccm, and the NH3 flow rate is 12100-12300sccm.

5. The metallization process of the low folding watt battery back film according to claim 4, characterized in that: The SiH4 flow rate in the fourth reaction furnace is 1200-1400sccm, and the NH3 flow rate is 15250-15450sccm.

6. A low folding watt battery back film, characterized in that: The low-folding-wattage battery back film is prepared by the metallization process of any one of claims 1-5, comprising a silicon oxynitride layer, a first silicon nitrogen layer, a second silicon nitrogen layer, and a third silicon nitrogen layer arranged in sequence from the inside to the outside, wherein the silicon nitrogen ratio of the first silicon nitrogen layer is 1:4.6-4.9, the silicon nitrogen ratio of the second silicon nitrogen layer is 1:8.9-9.1, and the silicon nitrogen ratio of the third silicon nitrogen layer is 1:11.7-11.

9.

7. The low folding watt battery back film according to claim 6, characterized in that: The silicon-nitrogen ratio of the silicon oxynitride layer is 1:6.1-6.

3.

8. A shingled battery, characterized in that: It comprises a front film, a silicon substrate layer and the low-folding-watt battery back film as described in claim 6, wherein the front film is arranged on the front side of the silicon substrate layer, and the low-folding-watt battery back film is arranged on the back side of the silicon substrate layer.

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