TOPCon electroplated battery and edge passivation method for reducing cutting damage of TOPCon electroplated battery

Abstract

The invention discloses a TOPCon electroplated cell and an edge passivation method for reducing cutting damage of the TOPCon electroplated cell, and relates to the technical field of solar cells. The method comprises the following steps: growing a layer of aluminum oxide film on the surfaces and edges of a plurality of small battery pieces formed by laser slicing, and then sintering, annealing and carrying out light injection to obtain passivated small battery pieces; and coating the edge of the passivated small battery piece with a layer of UV glue, and then carrying out ultraviolet radiation, acid pickling, water washing and drying to obtain the edge-passivated small battery piece. Edge passivation is completed before nickel, copper and tin are electroplated to manufacture the grid line, the effect of repairing cutting damage is achieved, a high-temperature process is not needed subsequently, the adhesive force of the electroplated grid line can be guaranteed, and the efficiency of the cut battery is improved.

Description

Technical Field

[0001] The invention relates to the technical field of solar cells, and in particular to a TOPCon electroplating cell and an edge passivation method for reducing cutting damage thereof. Background Art

[0002] The existing TOPCon cells are rapidly replacing PERC cell technology with higher efficiency and cost advantages. The front and back of TOPCon cells are printed with silver paste, and the silver paste cost now accounts for more than 20% of the total cell cost. Currently, many photovoltaic manufacturers have begun to use electroplating technology to make TOPCon cells, reducing cell costs by replacing silver paste with materials such as nickel, copper, tin, and zinc.

[0003] The current TOPCon cells are generally cut into two or three pieces to make modules. This method can reduce the internal power loss of the module by reducing the module current and internal resistance. However, the efficiency of TOPCon cells is lost by about 0.25% per cut after laser cutting, so the edge passivation of the cutting position is required to reduce cutting damage.

[0004] The edge passivation process currently used in conventional TOPCon cells is to grow an aluminum oxide layer on the cut edge to repair the cutting damage and the resulting dangling bonds to achieve the purpose of improving efficiency. This edge passivation method requires a long period of high-temperature passivation treatment. After the current TOPCon electroplating cells have completed the grid line production, they will be subjected to a high temperature of more than 300°C, which will lead to problems such as reduced welding tension and efficiency. Therefore, the current conventional TOPCon cell edge passivation process cannot be applied to electroplated cells.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The object of the present invention is to provide an edge passivation method for reducing cutting damage of a TOPCon electroplating cell, a TOPCon electroplating cell and a photovoltaic module.

[0007] The present invention is achieved in that:

[0008] In a first aspect, the present invention provides an edge passivation method for reducing cutting damage of TOPCon electroplating cells, comprising:

[0009] A layer of aluminum oxide film is grown on the surface and edge of a plurality of battery chips formed by laser slicing, followed by sintering annealing and light injection to activate the passivation effect, thereby obtaining a passivated battery chip;

[0010] A layer of UV glue is coated on the edge of the passivated battery chip, and then the UV glue is cured by ultraviolet irradiation to form a UV protective layer of the aluminum oxide film for protecting the edge. The aluminum oxide film on the surface of the passivated battery chip is then removed by acid washing, washed with water and dried to obtain an edge passivated battery chip.

[0011] In an optional embodiment, the growth thickness of the aluminum oxide film is 5 to 50 nm;

[0012] Preferably, the method for growing the aluminum oxide film is ALD or PECVD;

[0013] Preferably, before growing the aluminum oxide film, the battery chips of the same size are stacked with their polished surfaces back to back and inserted into an aluminum boat, and then the aluminum oxide film is grown.

[0014] In an optional embodiment, the thickness of the UV glue is 10 to 50 μm;

[0015] Preferably, the irradiation intensity of the ultraviolet irradiation is 1500-5000 mW / cm 2 , irradiation time is 5 to 50 seconds;

[0016] Preferably, the pickling acid is hydrochloric acid with a mass percentage concentration of 3% to 15%, and the pickling time is 50 to 500 seconds.

[0017] In an optional embodiment, the sintering annealing includes high temperature annealing at 300 to 900° C. for 30 to 200 seconds;

[0018] Preferably, the sintering annealing is performed in a tunnel sintering furnace.

[0019] In an optional embodiment, the light injection includes applying light with an intensity of 10 to 30 suns to the sintered and annealed cell chip at 100 to 200° C. for 20 to 100 seconds using an LED lamp.

[0020] In a second aspect, the present invention provides a method for preparing a TOPCon electroplated cell, which includes laser grooving on a blue film sheet after depositing silicon nitride films on both sides, and then passivating the sliced ​​cell pieces using an edge passivation method for reducing cutting damage to TOPCon electroplated cells as described in any of the above embodiments, and then sequentially plating a nickel layer, a copper layer and a tin layer in the double-sided laser grooves of the edge-passivated cell pieces.

[0021] In an optional embodiment, the thickness of the nickel layer is 0.5 to 2.5 μm; the thickness of the copper layer is 5 to 10 μm, and the thickness of the tin layer is 0.5 to 2 μm;

[0022] Preferably, before the nickel layer is plated in the double-sided laser grooves of the edge passivated battery chip, the edge passivated battery chip is also placed in hydrofluoric acid with a mass percentage concentration of 1% to 5% for cleaning for 20 to 60 seconds.

[0023] In an optional embodiment, the blue film sheet after the double-sided deposition of silicon nitride film comprises a battery substrate, an n-type doped surface and a p-type doped surface respectively arranged on both sides of the battery substrate, the n-type doped surface comprises a tunneling oxide layer, a phosphorus-doped polysilicon layer and a first silicon nitride layer from the inside to the outside, and the p-type doped surface comprises a boron-doped polysilicon layer, an aluminum oxide layer and a second silicon nitride layer from the inside to the outside;

[0024] Preferably, the laser grooving removes the insulating first silicon nitride layer and part of the phosphorus-doped polysilicon layer in the n-type doped surface, and simultaneously removes the insulating second silicon nitride layer, the aluminum oxide layer and part of the boron-doped polysilicon layer in the p-type doped surface.

[0025] In an optional embodiment, after the laser slicing, the blue film sheet is divided into 2 to 4 battery small sheets.

[0026] In a third aspect, the present invention provides a TOPCon electroplating cell, which is assembled from TOPCon electroplating cell sheets prepared by the method for preparing a TOPCon electroplating cell sheet as described in any one of the aforementioned embodiments.

[0027] In a fourth aspect, the present invention provides a photovoltaic module, comprising a laminate and a frame wrapped around the laminate, wherein along the direction of illumination, the laminate comprises a front panel, a first packaging film, a photovoltaic cell, a second packaging film and a back panel arranged in sequence, and the photovoltaic cell comprises the TOPCon electroplated cell described in the aforementioned embodiment.

[0028] The present invention has the following beneficial effects:

[0029] The edge passivation method for reducing the cutting damage of TOPCon electroplated batteries provided by the present invention performs laser slicing and growing an aluminum oxide film on a large battery sheet, then protects the aluminum oxide film on the edge of the slice by UV glue, and removes the aluminum oxide film on the surface by pickling, so that only the edge of the small battery sheet is passivated, and the surface passivation layer is removed, which is convenient for subsequent electroplating of nickel, copper and tin to make grid lines. In addition, the edge passivation in the present invention is completed before the grid lines are made by electroplating nickel, copper and tin, so as to achieve the effect of repairing the cutting damage. After the subsequent process of electroplating the grid lines is completed, no high-temperature process is required, which can ensure the adhesion of the electroplated grid lines and improve the efficiency of the battery after cutting. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 A schematic diagram of the structure of the TOPCon electroplating cell provided by the present invention;

[0032] Figure 2 This is a schematic structural diagram of a blue film after silicon nitride films are deposited on both sides provided by the present invention.

[0033] Icons: 100-TOPCon electroplating cell; 110-blue film after double-sided deposition of silicon nitride film; 111-cell substrate; 112-n-type doped surface; 113-p-type doped surface; 114-tunneling oxide layer; 115-phosphorus-doped polysilicon layer; 116-first silicon nitride layer; 117-boron-doped polysilicon layer; 118-aluminum oxide layer; 119-second silicon nitride layer; 120-cell chip; 130-aluminum oxide film; 140-UV protective layer; 150-nickel layer; 160-copper layer; 170-tin layer. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0035] See also Figure 1 and Figure 2 The present invention provides an edge passivation method for reducing cutting damage of a TOPCon electroplating cell 100, which comprises:

[0036] A layer of aluminum oxide film 130 is grown on the surface and edge of a plurality of battery chips 120 formed by laser slicing, followed by sintering, annealing and light injection to activate the passivation effect, thereby obtaining a passivated battery chip;

[0037] A layer of UV glue is coated on the edge of the passivated battery chip, and then the UV glue is cured by ultraviolet irradiation to form a UV protective layer 140 of the aluminum oxide film 130 for protecting the edge. The aluminum oxide film 130 on the surface of the passivated battery chip is then removed by acid washing, washed with water and dried to obtain an edge passivated battery chip.

[0038] The present invention uses a blue film as a workpiece, performs laser grooving, laser slicing, and growing an aluminum oxide film 130 on its surface, and then protects the aluminum oxide film 130 at the edge of the slice with UV glue, and removes the aluminum oxide film 130 on the surface by pickling, so that only the edge of the battery chip 120 is passivated, and the surface passivation layer is removed, which is convenient for subsequent electroplating of nickel, copper and tin to make grid lines. In addition, the edge passivation in the present invention is completed before electroplating nickel, copper and tin to make grid lines, so as to achieve the effect of repairing cutting damage. After the subsequent process of electroplating the grid lines is completed, no high-temperature process is required, and the adhesion of the electroplated grid lines can be guaranteed.

[0039] Specifically, the method for preparing a TOPCon electroplated cell provided by the present invention comprises the following steps S1-S9, wherein steps S2-S6 are specific steps of the edge passivation method for reducing cutting damage of the TOPCon electroplated cell 100. Specifically, the method comprises the following steps:

[0040] S1. Laser grooving.

[0041] Laser grooving is performed on the blue film 110 after silicon nitride films are deposited on both sides.

[0042] The blue film sheet 110 after double-sided deposition of silicon nitride film includes a battery substrate 111, an n-type doped surface 112 and a p-type doped surface 113 respectively arranged on both sides of the battery substrate 111, the n-type doped surface 112 includes a tunneling oxide layer 114, a phosphorus-doped polysilicon layer 115 and a first silicon nitride layer 116 from the inside to the outside, and the p-type doped surface 113 includes a boron-doped polysilicon layer 117, an aluminum oxide layer 118 and a second silicon nitride layer 119 from the inside to the outside. The deposition method of the above n-type doped surface 112 and the p-type doped surface 113 can be carried out in accordance with the conventional method.

[0043] In the present invention, a blue film is used as a workpiece, and laser grooves are made on its surface to facilitate subsequent electroplating operations. The laser grooves are used to remove the insulating first silicon nitride layer 116 and part of the phosphorus-doped polysilicon layer 115 in the n-type doped surface 112, and at the same time, the insulating second silicon nitride layer 119, the aluminum oxide layer 118 and part of the boron-doped polysilicon layer 117 in the p-type doped surface 113 are removed.

[0044] S2, laser sectioning.

[0045] After laser slicing, the blue film sheet is divided into 2 to 4 small battery sheets 120 .

[0046] The laser slicing process in the present invention is a non-destructive cutting process, which is used to cut 2 to 4 designed battery chips 120. The graphic designs of the 2 to 4 battery chips 120 can be the same or different.

[0047] Although the lossless cutting process can reduce the loss, it is still difficult to avoid a loss of about 0.25% per cut, so the edge of the cutting position needs to be passivated to reduce cutting damage.

[0048] S3 . Grow an aluminum oxide film 130 .

[0049] A layer of aluminum oxide film 130 is grown on the surface and edge of the battery chip 120, and the growth thickness of the aluminum oxide film 130 is 5 to 50 nm; the method of growing the aluminum oxide film 130 is ALD or PECVD. In the present invention, by growing the aluminum oxide film 130 on the surface and edge of the battery chip 120 at the same time, it is ensured that the aluminum oxide film 130 can completely cover the cut edge of the battery chip 120 to repair the cutting damage.

[0050] In the present invention, by limiting the growth thickness of the aluminum oxide film 130 to 5 to 50 nm, it can be ensured that the aluminum oxide film 130 has a good effect of repairing cutting damage on the cutting edge. When the growth thickness is too small, it cannot effectively play a repairing effect, and when the growth thickness is too large, it will cause a waste of resources and increase the volume of the battery cell.

[0051] In the present invention, the aluminum oxide film 130 can be grown for each battery chip 120 separately, or two battery chips 120 of the same size can be stacked with the polished surfaces back to back and inserted into an aluminum boat, and then the aluminum oxide film 130 can be grown. By stacking the two battery chips 120 with the polished surfaces back to back, the aluminum oxide film 130 can be grown on the two battery chips 120 at one time, which is more convenient.

[0052] At the same time, in the present invention, two battery sheets 120 are stacked with polished surfaces back to back, where the polished surfaces of the two battery sheets 120 are close together, which can reduce the generation of friction. At the same time, in the present invention, there is no need to achieve close stacking by pressurization, so as to avoid product fragmentation. In order to avoid the aluminum oxide winding to the surface of the battery sheet, conventional battery sheets use hundreds of pieces to be closely stacked, and only the cutting position is exposed to grow aluminum oxide. In the process of closely stacking conventional battery sheets, due to the pressurization operation and the difference in battery sheet thickness, it is easy to generate fragments, and the present application can effectively reduce the fragmentation rate.

[0053] S4. Sintering annealing.

[0054] The sintering annealing includes high temperature annealing at 300-900°C for 30-200s; preferably, the sintering annealing is performed in a tunnel sintering furnace to activate the passivation effect of the aluminum oxide layer 118, the aluminum oxide film 130 and the silicon nitride layer on the surface of the blue film, and also has an annealing effect on the laser grooving damage.

[0055] In the present invention, since the processing is performed on the basis of the blue film, rather than on the finished cell, the blue film of the present invention can be subjected to high temperature annealing at a relatively high temperature of 300 to 900° C. after the aluminum oxide film 130 is grown, so as to be quickly passivated. At the same time, the high temperature annealing treatment in the present invention is performed before the gate line made of nickel, copper and tin is electroplated, and there is no need to worry that the high temperature annealing will affect the welding tension between the gate line and the polysilicon layer.

[0056] S5. Light injection.

[0057] Light injection includes applying 10 to 30 suns of light intensity to the sintered and annealed cell chip 120 at 100 to 200° C. for 20 to 100 seconds using an LED lamp. The light injection can further activate the H+ ions in the passivation layer to passivate the cell chip.

[0058] S6. Edge protection.

[0059] The edge of the passivated cell chip is coated with a layer of UV glue with a thickness of 10 to 50 μm, and then the UV glue is cured by ultraviolet irradiation to form a UV protective layer 140 for protecting the aluminum oxide film 130 at the edge. The irradiation intensity of the ultraviolet irradiation is 1500 to 5000 mW / cm 2 The irradiation time is 5 to 50 seconds, so that the UV glue at the edge is cured to form a UV protective layer 140 to protect the aluminum oxide layer 118 on the side of the passivated battery chip.

[0060] S7. Pickling.

[0061] The above-mentioned edge-protected passivated battery chip is placed in an acid solution for pickling, wherein the pickling acid is hydrochloric acid with a mass percentage concentration of 3% to 15%, and the pickling time is 50 to 500 seconds. During the pickling process, the edge of the passivated battery chip is protected by the UV protective layer 140 formed by the curing of the UV glue and will not be removed by pickling, while the aluminum oxide film 130 on the surface of the passivated battery chip is not protected, so it is easy to be removed during the pickling process. At the same time, pickling can also wash away metal impurities in the previous process. After the aluminum oxide film 130 on the surface of the passivated battery chip is completely removed by pickling, it is washed with pure water to remove the hydrochloric acid on the surface, and then dried to obtain an edge passivated battery chip.

[0062] S8, double-sided nickel plating 150.

[0063] Before the nickel layer 150 is plated on the double-sided laser grooves of the edge passivated battery chip, the edge passivated battery chip is placed in a hydrofluoric acid with a mass percentage concentration of 1% to 5% for cleaning for 20 to 60 seconds. The hydrofluoric acid can effectively remove the oxide layer and residual trace silicon nitride on the exposed silicon surface at the grooved position.

[0064] Then, a nickel layer 150 with a thickness of 0.5 to 2.5 μm is plated on the laser grooved positions on both sides of the cell using an electroplating process. The nickel layer 150 mainly serves as an ohmic contact and prevents copper from diffusing into silicon.

[0065] S9, double-sided copper-tin plating layer 170.

[0066] The edge passivated battery cell with double-sided nickel plating is plated with a 5-10μm copper layer 160 and a 0.5-2μm tin layer 170 on the nickel layer 150 in turn by electroplating to complete the production of the battery cell. Copper plays a major role in the lateral transmission of current with its good electrical conductivity, and the outermost layer of tin protects copper from oxidation and improves the effect of welding with the welding strip.

[0067] Furthermore, the present invention also provides a TOPCon electroplating cell 100, which is prepared by the above-mentioned edge passivation method for reducing cutting damage of the TOPCon electroplating cell 100. The prepared TOPCon electroplating cell 100 has high welding tension and efficiency, and the TOPCon electroplating cell 100 has excellent performance.

[0068] In addition, the present invention also provides a photovoltaic module, including a laminate and a frame wrapped around the laminate. Along the light direction, the laminate includes a front panel, a first packaging film, a photovoltaic cell, a second packaging film and a back panel arranged in sequence, and the photovoltaic cell includes the above-mentioned TOPCon electroplated cell 100.

[0069] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0070] Example 1

[0071] This embodiment provides an edge passivation method for reducing cutting damage of a TOPCon electroplating cell 100, which includes:

[0072] S1. Laser grooving: laser grooving is performed on the blue film 110 after the silicon nitride film is deposited on both sides, and the insulating first silicon nitride layer 116 and part of the phosphorus-doped polysilicon layer 115 in the n-type doped surface 112 are removed. At the same time, the insulating second silicon nitride layer 119, the aluminum oxide layer 118 and part of the boron-doped polysilicon layer 117 in the p-type doped surface 113 are removed.

[0073] S2. Laser slicing: using a non-destructive cutting process to laser cut the blue film to form two small battery pieces 120 with the same graphic design.

[0074] S3. Growth of aluminum oxide film 130: Stack two battery chips 120 with their polished surfaces back to back and insert them into an aluminum boat. Use ALD to grow a layer of aluminum oxide film 130 on the surface and edge of the battery chip 120. The growth thickness of the aluminum oxide film 130 is 10 nm. The aluminum oxide film 130 can completely cover the cut edges of the battery chip 120 to repair cutting damage.

[0075] S4, sintering annealing: high temperature annealing at 600° C. for 100 seconds in a tunnel sintering furnace to activate the passivation effect of the aluminum oxide layer 118 and the silicon nitride layer on the surface of the blue film.

[0076] S5. Light injection: At 150° C., use an LED lamp to apply light with an intensity of 20 suns to the sintered and annealed cell chip 120 for 20 seconds. The light injection can further activate the H+ ions in the passivation layer to passivate the cell chip, thereby passivating the cell chip.

[0077] S6, edge protection: Coat the edge of the passivated cell with a 30μm thick layer of UV glue, and then irradiate with UV light at an intensity of 3000mW / cm 2 The irradiation time is 20 seconds, so that the UV glue at the edge is cured to form a UV protective layer 140 to protect the aluminum oxide layer 118 on the side of the passivation battery chip.

[0078] S7, pickling: the passivated battery chip which has been edge-protected in step S5 is placed in an acid solution for pickling, wherein the pickling acid is hydrochloric acid with a mass percentage concentration of 8%, and the pickling time is 200s to remove the aluminum oxide film 130 on the surface of the passivated battery chip, and then washed with pure water to remove the hydrochloric acid on the surface, and dried to obtain an edge-passivated battery chip.

[0079] S8, double-sided nickel plating 150: the edge passivated cell chip is placed in 3% by mass concentration hydrofluoric acid for cleaning for 40 seconds, and then a 1.5 μm nickel layer 150 is plated on the laser grooved positions on both sides of the cell chip using an electroplating process.

[0080] S9, double-sided copper-tin plating 170: the edge passivated battery cell that has been double-sided nickel plated is plated with an 8 μm copper layer 160 and a 1.2 μm tin layer 170 on the nickel layer 150 using an electroplating process to complete the production of the battery cell.

[0081] Example 2

[0082] This embodiment provides an edge passivation method for reducing cutting damage of a TOPCon electroplating cell 100, which includes:

[0083] S1. Laser grooving: laser grooving is performed on the blue film 110 after the silicon nitride film is deposited on both sides, and the insulating first silicon nitride layer 116 and part of the phosphorus-doped polysilicon layer 115 in the n-type doped surface 112 are removed. At the same time, the insulating second silicon nitride layer 119, the aluminum oxide layer 118 and part of the boron-doped polysilicon layer 117 in the p-type doped surface 113 are removed.

[0084] S2. Laser slicing: using a non-destructive cutting process to laser cut the blue film to form two small battery pieces 120 with the same graphic design.

[0085] S3. Growth of aluminum oxide film 130: stack two battery chips 120 with their polished surfaces back to back and insert them into an aluminum boat, and grow a layer of aluminum oxide film 130 on the surface and edge of the battery chip 120 using the ALD method. The growth thickness of the aluminum oxide film 130 is 5 nm. The aluminum oxide film 130 can completely cover the cut edges of the battery chip 120 to repair cutting damage.

[0086] S4, sintering annealing: high temperature annealing at 300° C. for 150 seconds in a tunnel sintering furnace to activate the passivation effect of the aluminum oxide layer 118 and the silicon nitride layer on the surface of the blue film.

[0087] S5. Light injection: At 100° C., use an LED lamp to apply light with an intensity of 10 suns to the sintered and annealed battery chip 120 for 30 seconds. Light injection can further activate the H+ ions in the passivation layer to passivate the battery chip, thereby passivating the battery chip.

[0088] S6, edge protection: Coat the edge of the passivated cell with a 10μm thick layer of UV glue, and then irradiate with UV light at an intensity of 1500mW / cm 2 The irradiation time is 30 seconds, so that the UV glue at the edge is cured to form a UV protective layer 140 to protect the aluminum oxide layer 118 on the side of the passivation battery chip.

[0089] S7, pickling: the passivated battery chip which has undergone edge protection in step S5 is placed in an acid solution for pickling, wherein the pickling acid is hydrochloric acid with a mass percentage concentration of 3%, and the pickling time is 500s, so as to remove the aluminum oxide film 130 on the surface of the passivated battery chip, and then washed with pure water to remove the hydrochloric acid on the surface, and dried to obtain an edge passivated battery chip.

[0090] S8, double-sided nickel plating 150: the edge passivated cell chip is placed in 1% by mass concentration hydrofluoric acid for cleaning for 60 seconds, and then a 0.5 μm nickel layer 150 is plated on the laser grooved positions on both sides of the cell chip using an electroplating process.

[0091] S9, double-sided copper-tin plating 170: the edge passivated battery cell that has been double-sided nickel plated is plated with a 5 μm copper layer 160 and a 0.5 μm tin layer 170 on the nickel layer 150 using an electroplating process to complete the production of the battery cell.

[0092] Example 3

[0093] This embodiment provides an edge passivation method for reducing cutting damage of a TOPCon electroplating cell 100, which includes:

[0094] S1. Laser grooving: laser grooving is performed on the blue film 110 after the silicon nitride film is deposited on both sides, and the insulating first silicon nitride layer 116 and part of the phosphorus-doped polysilicon layer 115 in the n-type doped surface 112 are removed. At the same time, the insulating second silicon nitride layer 119, the aluminum oxide layer 118 and part of the boron-doped polysilicon layer 117 in the p-type doped surface 113 are removed.

[0095] S2. Laser slicing: Using a non-destructive cutting process, laser cutting is performed on the blue film to form four small battery pieces 120 with the same graphic design.

[0096] S3. Growth of aluminum oxide film 130: Stack two battery chips 120 with their polished surfaces back to back and insert them into an aluminum boat. Use ALD method to grow a layer of aluminum oxide film 130 on the surface and edge of the battery chip 120. The growth thickness of the aluminum oxide film 130 is 15nm. The aluminum oxide film 130 can completely cover the cut edges of the battery chip 120 to repair cutting damage.

[0097] S4, sintering annealing: high temperature annealing at 900° C. for 30 seconds in a tunnel sintering furnace to activate the passivation effect of the aluminum oxide layer 118 and the silicon nitride layer on the surface of the blue film.

[0098] S5. Light injection: At 200° C., use an LED lamp to apply light with an intensity of 30 suns to the sintered and annealed battery chip 120 for 15 seconds. Light injection can further activate the H+ ions in the passivation layer to passivate the battery chip, thereby passivating the battery chip.

[0099] S6, edge protection: Coat the edge of the passivated cell with a 50μm thick layer of UV glue, and then irradiate with UV light at an intensity of 5000mW / cm 2 The irradiation time is 10 seconds, so that the UV glue at the edge is cured to form a UV protective layer 140 to protect the aluminum oxide layer 118 on the side of the passivation battery chip.

[0100] S7, pickling: the passivated battery chip which has been edge-protected in step S5 is placed in an acid solution for pickling, wherein the pickling acid is hydrochloric acid with a mass percentage concentration of 15%, and the pickling time is 50s, so as to remove the aluminum oxide film 130 on the surface of the passivated battery chip, and then washed with pure water to remove the hydrochloric acid on the surface, and dried to obtain an edge-passivated battery chip.

[0101] S8, double-sided nickel plating 150: the edge passivated cell chip is placed in 5% by mass concentration hydrofluoric acid for cleaning for 20 seconds, and then a 2.5 μm nickel layer 150 is plated on the laser grooved positions on both sides of the cell chip using an electroplating process.

[0102] S9, double-sided copper-tin plating 170: the edge passivated battery cell that has been double-sided nickel plated is plated with a 10 μm copper layer 160 and a 2 μm tin layer 170 on the nickel layer 150 using an electroplating process to complete the production of the battery cell.

[0103] Example 4

[0104] This embodiment is basically the same as Embodiment 1, except that, in this embodiment, before growing the aluminum oxide film 130 in step S3, the battery chips 120 of the same size are first stacked back to back with their polished surfaces and inserted into an aluminum boat, and then the aluminum oxide film 130 is grown.

[0105] Comparative Example 1

[0106] This comparative example provides a TOPCon electroplating cell 100, which does not perform passivation repair on the cut edge, and specifically includes the following steps:

[0107] S1. Laser grooving: laser grooving is performed on the blue film 110 after the silicon nitride film is deposited on both sides, and the insulating first silicon nitride layer 116 and part of the phosphorus-doped polysilicon layer 115 in the n-type doped surface 112 are removed. At the same time, the insulating second silicon nitride layer 119, the aluminum oxide layer 118 and part of the boron-doped polysilicon layer 117 in the p-type doped surface 113 are removed.

[0108] S2, double-sided nickel plating 150: the battery cell 120 is placed in a hydrofluoric acid with a mass percentage concentration of 1% to 5% for cleaning for 20 to 60 seconds, and then a 0.5 to 2.5 μm nickel layer 150 is plated on the laser grooved positions on both sides of the battery cell using an electroplating process.

[0109] S3, double-sided copper-tin plating 170: the edge passivated battery piece that has been plated with double-sided nickel is plated with a 5-10 μm copper layer 160 and a 0.5-2 μm tin layer 170 on the nickel layer 150 using an electroplating process to complete the production of the entire battery piece.

[0110] S4, laser slicing: using a non-destructive cutting process to laser cut the entire battery sheet to form 2 to 4 small battery sheets 120 with the same graphic design.

[0111] Comparative Example 2

[0112] This comparative example provides a TOPCon electroplating cell 100, which is passivated by a conventional edge passivation method, which specifically includes the following steps:

[0113] S1. Laser grooving: laser grooving is performed on the blue film 110 after the silicon nitride film is deposited on both sides, and the insulating first silicon nitride layer 116 and part of the phosphorus-doped polysilicon layer 115 in the n-type doped surface 112 are removed. At the same time, the insulating second silicon nitride layer 119, the aluminum oxide layer 118 and part of the boron-doped polysilicon layer 117 in the p-type doped surface 113 are removed.

[0114] S2. Double-sided nickel plating 150: The blue film is placed in hydrofluoric acid with a mass percentage concentration of 1% to 5% for cleaning for 20 to 60 seconds, and then a 0.5 to 2.5 μm nickel layer 150 is plated on the laser grooved positions on both sides of the battery cell using an electroplating process.

[0115] S3, double-sided copper-tin plating 170: the edge passivated battery chip that has been double-sided nickel plated is plated with a 5-10 μm copper layer 160 and a 0.5-2 μm tin layer 170 on the nickel layer 150 in sequence using an electroplating process.

[0116] S4, laser slicing: laser cutting the battery cell using a non-destructive cutting process to form 2 to 4 battery cells 120 with the same graphic design.

[0117] S5. The cut battery pieces 120 are stacked and pressurized. The number of stacked battery strips is 2 and the pressurization pressure is 1N.

[0118] S6. The cut battery strips are plated with a layer of aluminum oxide film 130 in an ALD device. The thickness of the aluminum oxide film 130 is 10 nm.

[0119] S7, subjecting the coated battery strip to an annealing heat repair treatment at 200° C. for 120 seconds with a nitrogen flow rate of 10 L / min, to obtain a repaired battery strip.

[0120] Comparative Example 3

[0121] This comparative example is basically the same as Example 1, except that the position of the laser sectioning is different.

[0122] This comparative example includes:

[0123] S1 is the same as that in Example 1. After S1, steps S4 and S5 in Example 1 are performed. After the light injection in S5, S2 and S3 in Example 1 are performed, and then subsequent S6-S9 are performed in sequence.

[0124] Test Case

[0125] The finished battery chips obtained in the above Examples 1-4 and Comparative Examples 1-3 were subjected to efficiency and tensile tests.

[0126] 1. Efficiency test: Use IV test machine to test the efficiency of finished battery cells, and measure the efficiency of the cells before and after cutting and before and after passivation.

[0127] 2. Tensile test: Place the soldering ribbon coated with flux on the main grid line of the battery cell, bake it on a platform at 250℃ for 10s, and then use a tensile tester to test the fixed soldering ribbon and the adhesion of the main grid line.

[0128] Please refer to Table 1 for specific test results.

[0129] Table 1. Test results of finished battery chips provided by different examples

[0130]

[0131] As can be seen from the above table, the edge passivation method of the present invention can effectively repair the cutting damage of the electroplated battery cell, and the passivation repair efficiency is significantly higher than that of comparative examples 1-3. At the same time, embodiments 1-4 of the present invention can also maintain the adhesion of the grid line, and the fragmentation rate is also maintained at a low level. Among them, comparative example 1 provides a battery that has not been passivated and repaired. At this time, the efficiency of the battery after cutting cannot be effectively restored, which will lead to a significant reduction in efficiency. In comparative example 2, a conventional edge passivation method is used. At this time, the passivation repair efficiency is significantly lower than that of embodiments 1-4 of the present invention. At the same time, the fragmentation rate is significantly increased, and the welding tension is significantly reduced. In comparative example 3, the laser slicing and growth of the aluminum oxide film 130 are arranged after the light injection. At this time, because the coated aluminum oxide film has not been activated by sintering annealing and light injection, the passivation effect of the aluminum oxide film 130 is poor, and the passivation repair efficiency is significantly lower than that of embodiment 1.

[0132] In summary, the edge passivation method for reducing cutting damage of TOPCon electroplated cells 100 provided by the present invention uses a blue film as a workpiece, performs laser grooving, laser slicing, and grows an aluminum oxide film 130 on its surface, and then protects the aluminum oxide film 130 at the edge of the slice with UV glue, and removes the aluminum oxide film 130 on the surface by pickling, so that only the edge of the battery chip 120 is passivated, and the surface passivation layer is removed, which is convenient for subsequent electroplating of nickel, copper and tin to make grid lines. In addition, the edge passivation in the present invention is completed before electroplating nickel, copper and tin to make grid lines, so as to achieve the effect of repairing cutting damage. After the subsequent process of electroplating the grid lines is completed, no high-temperature process is required, which can ensure the adhesion of the electroplated grid lines and improve the efficiency of the battery after cutting.

[0133] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An edge passivation method for reducing cutting damage of TOPCon electroplating cells, characterized in that: It includes: A layer of aluminum oxide film is grown on the surface and edge of a plurality of battery chips formed by laser slicing, followed by sintering annealing and light injection to activate the passivation effect, thereby obtaining a passivated battery chip; A layer of UV glue is coated on the edge of the passivated battery chip, and then the UV glue is cured by ultraviolet irradiation to form a UV protective layer of the aluminum oxide film for protecting the edge. The aluminum oxide film on the surface of the passivated battery chip is then removed by acid washing, washed with water and dried to obtain an edge passivated battery chip.

2. The edge passivation method for reducing cutting damage of TOPCon electroplating cells according to claim 1, characterized in that: The growth thickness of the aluminum oxide film is 5 to 50 nm; Preferably, the method for growing the aluminum oxide film is ALD or PECVD; Preferably, before growing the aluminum oxide film, the battery chips of the same size are stacked with their polished surfaces back to back and inserted into an aluminum boat, and then the aluminum oxide film is grown.

3. The edge passivation method for reducing cutting damage of TOPCon electroplating cells according to claim 1, characterized in that: The thickness of the UV glue is 10 to 50 μm; Preferably, the irradiation intensity of the ultraviolet irradiation is 1500-5000 mW / cm 2 , irradiation time is 5 to 50 seconds; Preferably, the pickling acid is hydrochloric acid with a mass percentage concentration of 3% to 15%, and the pickling time is 50 to 500 seconds.

4. The edge passivation method for reducing cutting damage of TOPCon electroplating cells according to claim 1, characterized in that: The sintering annealing includes high temperature annealing at 300-900°C for 30-200s; Preferably, the sintering annealing is performed in a tunnel sintering furnace.

5. The edge passivation method for reducing cutting damage of TOPCon electroplating cells according to claim 1, characterized in that: The light injection includes applying light with an intensity of 10 to 30 suns to the sintered and annealed cell chip for 20 to 100 seconds at 100 to 200° C. using an LED lamp.

6. A method for preparing a TOPCon electroplated cell, characterized in that: The method comprises laser grooving on a blue film sheet after silicon nitride films are deposited on both sides, and then passivating the sliced ​​battery slices according to the edge passivation method for reducing TOPCon electroplating battery cutting damage as described in any one of claims 1 to 5, and then sequentially plating nickel layers, copper layers and tin layers in the double-sided laser grooves of the edge passivated battery slices.

7. The method for preparing a TOPCon electroplated cell according to claim 6, characterized in that: The thickness of the nickel layer is 0.5 to 2.5 μm; the thickness of the copper layer is 5 to 10 μm, and the thickness of the tin layer is 0.5 to 2 μm; Preferably, before the nickel layer is plated in the double-sided laser grooves of the edge passivated battery chip, the edge passivated battery chip is also placed in hydrofluoric acid with a mass percentage concentration of 1% to 5% for cleaning for 20 to 60 seconds.

8. The method for preparing a TOPCon electroplated cell according to claim 6, characterized in that: The blue film after double-sided deposition of silicon nitride film comprises a battery substrate, an n-type doped surface and a p-type doped surface respectively arranged on two sides of the battery substrate, wherein the n-type doped surface comprises a tunneling oxide layer, a phosphorus-doped polysilicon layer and a first silicon nitride layer in sequence from inside to outside, and the p-type doped surface comprises a boron-doped polysilicon layer, an aluminum oxide layer and a second silicon nitride layer in sequence from inside to outside; Preferably, the laser grooving removes the insulating first silicon nitride layer and part of the phosphorus-doped polysilicon layer in the n-type doped surface, and simultaneously removes the insulating second silicon nitride layer, the aluminum oxide layer and part of the boron-doped polysilicon layer in the p-type doped surface; Preferably, after the laser slicing, the blue film sheet is divided into 2 to 4 battery small sheets.

9. A TOPCon electroplating cell, characterized in that: It is assembled from TOPCon electroplated cell sheets prepared by the method for preparing TOPCon electroplated cell sheets as described in any one of claims 6 to 8.

10. A photovoltaic module, characterized in that: It comprises a laminate and a frame wrapped around the laminate. Along the light direction, the laminate comprises a front plate, a first packaging film, a photovoltaic cell, a second packaging film and a back plate arranged in sequence. The photovoltaic cell comprises the TOPCon electroplating cell described in claim 9.

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