A novel composite electrode for crystalline silicon solar cells and a method for making the same

Abstract

The application discloses a novel crystal silicon solar cell composite electrode and a preparation method thereof, and belongs to the technical field of crystal silicon solar cells. The novel crystal silicon solar cell composite electrode comprises grid lines arranged on the surface of a cell piece, the grid lines comprise a plurality of main grids and a plurality of auxiliary grids, the plurality of main grids are parallel and spaced apart, the plurality of auxiliary grids are parallel and spaced apart, the plurality of main grids and the plurality of auxiliary grids are distributed in a net structure, each main grid comprises a main grid silver electrode and a plurality of pairs of lap joints, the plurality of pairs of lap joints are distributed along the direction of the main grid silver electrode, each pair of lap joints is symmetrically distributed on the two sides of the main grid silver electrode, each auxiliary grid comprises a plurality of auxiliary grid non-silver metal electrodes, the end part of the auxiliary grid non-silver metal electrode close to the main grid silver electrode corresponds to a lap joint, and the surface of each auxiliary grid non-silver metal electrode is covered with a light-cured glue layer. The application provides a novel crystal silicon solar cell composite electrode structure, and aims to solve the problems of high metal cost of a current photovoltaic cell and poor copper oxidation resistance.

Description

Technical Field

[0001] This invention relates to the field of crystalline silicon solar cell technology, and more specifically, to a novel crystalline silicon solar cell composite electrode and its preparation method. Background Technology

[0002] Currently, the non-silver metal electrodes for the secondary grid of crystalline silicon solar cells are all silver electrodes. Global silver reserves are approximately 640,000 tons, and the global silver supply is projected to be around 26,000 tons in 2025, with slow growth or even a decline. Historically, crystalline silicon solar cells have attempted to replace silver electrodes with various base metallization technologies, such as copper electroplating and low-temperature silver-clad copper. Copper electroplating is considered one of the ideal solutions for achieving "complete silver removal," with significant long-term advantages. By directly forming copper grid lines on the cell surface through electroplating, the cost of silver can theoretically be almost completely eliminated, with raw material costs only about 1% of silver paste. However, its high initial capital expenditure (CAPEX) and complex processes pose a core challenge to yield control. The ultimate "silver-free" solution is pure copper paste, which is the industry's desired final solution. This involves using pure copper paste through screen printing to achieve the lowest material cost and the highest process compatibility. However, as of now, pure copper paste is still largely in the research and development and small-scale trial stages. Its core technological bottlenecks lie in the fact that issues such as copper's oxidation resistance, adhesion to silicon, and welding stability have not yet been perfectly resolved. Therefore, improving oxidation resistance is key to realizing the replacement of silver paste with copper paste and its application in UV photo-sintering of solar cells. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a novel crystalline silicon solar cell composite electrode and its preparation method.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A novel composite electrode for crystalline silicon solar cells includes an alumina film layer, a silicon nitride film layer, and grid lines on the surface of the cell. The grid lines include multiple main grids and multiple sub-grids. The main grids are parallel and spaced apart, and the sub-grids are parallel and spaced apart, forming a mesh structure. Each main grid includes a main grid silver electrode and multiple pairs of overlapping points. The pairs of overlapping points are distributed along the direction of the main grid silver electrode, and each pair of overlapping points is symmetrically distributed on both sides of the main grid silver electrode and connected to the main grid silver electrode. Each sub-grid includes multiple segments of non-silver metal electrodes. Each segment of the non-silver metal electrode is embedded in the surface of the cell, and the end of the non-silver metal electrode near the main grid silver electrode overlaps with a corresponding overlapping point. The surface of each non-silver metal electrode is covered with a photocurable adhesive layer.

[0006] A novel method for preparing a composite electrode for a crystalline silicon solar cell involves preparing grid lines and a photocurable adhesive layer on the surface of the solar cell. The specific steps are as follows:

[0007] S1. Take a battery cell and print silver paste on the surface of the battery cell; dry the silver paste on the battery cell to form the main grid silver electrode and the bonding point;

[0008] S2. Take the battery cell prepared in S1 and print a non-silver metal-coated copper powder paste on the surface of the battery cell; dry the non-silver metal-coated copper powder paste on the battery cell to form the non-silver metal electrode of the sub-grid.

[0009] S3. Take the battery cell prepared in S2 and print a photocurable adhesive on the surface of the non-silver metal electrode of the sub-gate; sinter the battery cell with UV light to form the photocurable adhesive layer on the surface of the non-silver metal electrode of the sub-gate.

[0010] Further, in step S1, the size of the battery cell is (180~184) mm × (200~220) mm.

[0011] Further, in step S1, the printing width of the main grid silver electrode is 20~50μm, the printing length of the overlap point is 100~2000μm and the printing width is 50~500μm, the printing height of the main grid silver electrode and the overlap point is 2~5μm, the number of main grid silver electrodes is 12~20, and the wet weight of the printed silver paste is 8~15mg / piece.

[0012] Further, in step S2, the width of the sub-gate non-silver metal electrode is 10~30μm, and the printing height of the sub-gate non-silver metal electrode (4) is 2~10μm.

[0013] Furthermore, in step S2, there are a total of 180 to 300 non-silver metal electrodes for the sub-gate, and the wet weight of the non-silver metal copper-coated powder slurry is 35 to 80 mg / piece.

[0014] Furthermore, in step S3, the transmittance of the photocurable adhesive layer to natural light is 97-99%.

[0015] Further, in step S3, the printing width of the photocurable adhesive layer is 80~500μm, the printing height is 3~20μm, the wet weight of the photocurable adhesive is 80~200mg / sheet, and the UV light irradiation time is 5~90s.

[0016] In summary, the present invention has the following beneficial effects:

[0017] This invention provides a novel method for preparing composite electrodes for crystalline silicon solar cells, aiming to solve the problems of high metal costs and poor oxidation resistance of copper in current photovoltaic cells. Attached Figure Description

[0018] Figure 1 A partial top view of a composite electrode for a crystalline silicon solar cell;

[0019] Figure 2 This is a partial structural diagram of a composite electrode for a crystalline silicon solar cell with grid lines fabricated on both the front and back sides.

[0020] In the diagram: 1. Solar cell; 2. Silver electrode of main grid; 3. Overlap point; 4. Non-silver metal electrode of sub-grid; 5. Photocurable adhesive layer. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The structure of the novel crystalline silicon solar cell composite electrode is as follows: it includes an aluminum oxide film layer, a silicon nitride film layer, a cell 1 after preparation, and grid lines on the surface of the cell 1. If it is used for TOPCon cells, grid lines are provided on both the upper and lower surfaces. If it is used to prepare BC cells, grid lines are provided on the lower surface. The grid lines include multiple main grids and multiple sub-grids. The main grids are parallel and spaced apart, and the sub-grids are parallel and spaced apart, forming a mesh structure. Each main grid includes a main grid silver electrode 2 and multiple pairs of contact points 3. The multiple pairs of contact points 3 are distributed along the direction of the main grid silver electrode 2, with each pair of contact points 3 symmetrically distributed on both sides of the main grid silver electrode 2, and each pair of contact points 3 connected to the main grid silver electrode 2. Each sub-grid includes multiple sub-grid non-silver metal electrodes 4, each sub-grid non-silver metal electrode 4 embedded in the surface of the cell 1. The end of the sub-grid non-silver metal electrode 4 near the main grid silver electrode 2 corresponds to a contact point 3 (the end of the sub-grid non-silver metal electrode 4 contacting the contact point 3 is at a right angle, with the right angle turning direction facing the main grid silver electrode 2 and the contact point 3). The surface of each sub-grid non-silver metal electrode 4 is covered with a photocurable adhesive layer 5, such as... Figure 1 The image shown is a partial top view of a composite electrode in a crystalline silicon solar cell. Figure 2 The diagram shown is a partial structural diagram of a composite electrode for a crystalline silicon solar cell with grid lines fabricated on both the front and back sides.

[0023] The photocurrent generated by the crystalline silicon solar cell when exposed to light is collected by the non-silver metal electrode 4 of the sub-grid, and then flows to the junction point 3 and then to the silver electrode 2 of the main grid. The photocurable adhesive layer 5 protects the copper substrate of the non-silver metal electrode 4 from oxidation. The non-silver metal electrode 4 of the sub-grid forms a good ohmic contact with the cell 1, which can effectively collect the photocurrent generated by the cell 1 and flow it to the silver electrode 2 of the main grid.

[0024] The preparation method of the novel crystalline silicon solar cell composite electrode is as follows:

[0025] S1. Print silver paste on the surface of the battery cell 1. The size of the battery cell 1 is (180~184) mm × (200~220) mm. The printing width of the main grid silver electrode 2 is 20~50 μm. The printing length of the overlap point 3 is 100~2000 μm and the width is 50~500 μm.

[0026] The silver paste on the battery cell 1 is dried to form the main grid silver electrode 2 and the overlap point 3. The printing height of the main grid silver electrode 2 and the overlap point 3 is 2~5μm, the number of main grid silver electrodes 2 is 12~20, and the wet weight of the printed silver paste is 8~15mg / piece.

[0027] S2. Take the battery cell 1 prepared in S1 and print a non-silver metal-coated copper powder paste on the surface of the battery cell 1. The wet weight of the non-silver metal-coated copper powder paste is 35~80mg / cell.

[0028] The non-silver metal-coated copper powder paste on the battery cell 1 is dried to form the sub-gate non-silver metal electrode 4. The width of the sub-gate non-silver metal electrode 4 is 10~30μm, the printing height of the sub-gate non-silver metal electrode 4 is 2~10μm, and there are a total of 180~300 sub-gate non-silver metal electrodes 4.

[0029] S3. Take the battery cell 1 prepared in S2 and print a photocurable adhesive on the surface of the non-silver metal electrode 4 of the sub-grid.

[0030] The solar cell 1 is sintered using UV light to form the photocurable adhesive layer 5 on the surface of the non-silver metal electrode 4 of the sub-grid. The transmittance of the photocurable adhesive layer 5 to natural light is 97-99%. The printing width of the photocurable adhesive layer 5 is 80-500 μm, the printing height is 3-20 μm, the wet weight of the photocurable adhesive is 80-200 mg / piece, and the UV light irradiation time is 5-90 s.

[0031] The fabrication method of this composite electrode structure can also be used for full back contact solar cells and perovskite / silicon tandem solar cells.

[0032] Example 1:

[0033] The composite electrode structure of a crystalline silicon solar cell includes a solar cell 1 with an aluminum oxide film layer and a silicon nitride layer covering its upper and lower surfaces, and grid lines respectively disposed on the upper and lower surfaces of the solar cell 1. The grid lines include multiple main grids and multiple sub-grids. The multiple main grids are parallel and spaced apart, and the multiple sub-grids are parallel and spaced apart, forming a mesh structure. Each main grid includes a main grid silver electrode 2 and multiple pairs of overlapping points 3. The multiple pairs of overlapping points 3 are distributed along the direction of the main grid silver electrode 2, and each pair of overlapping points 3 is symmetrically distributed on the main grid silver electrode 2. Both sides, and each pair of the overlapping points 3 are connected to the main grid silver electrode 2. Each sub-grid includes multiple sub-grid non-silver metal electrodes 4. Each sub-grid non-silver metal electrode 4 is embedded in the surface of the cell 1. The end of the sub-grid non-silver metal electrode 4 near the main grid silver electrode 2 overlaps with the overlapping point 3 (the end of the sub-grid non-silver metal electrode 4 that overlaps with the overlapping point 3 is at a right angle, and the right angle turning direction of the end faces the main grid silver electrode 2 and the overlapping point 3). The surface of each sub-grid non-silver metal electrode 4 is covered with a photocurable adhesive layer 5.

[0034] The preparation method is as follows:

[0035] Step 1: Fabricate the back main grid silver electrode 2 and the overlap point 3

[0036] (1) The battery cell 1 was prepared according to the method of steps (1)-(4) in Example 1 of the patent “An N-type TOPCon battery and its preparation method” (Publication No.: CN113611756A).

[0037] (2) With the back side facing up, a 182mm×210mm battery cell 1 is printed with silver paste on the back surface of the battery cell 1 by screen printing process; the wet weight of the silver paste is 10mg / piece, of which silver accounts for 90% by mass, and the rest is composed of organic solvent, glass powder and inorganic additives (7% organic solvent, 2% glass powder, 1% inorganic additives, the organic solvent is pentaerythritol triacrylate, and the inorganic additives are 0.5% aluminum powder and 0.5% silicon powder).

[0038] The printed battery cell 1 is sent into a chain drying oven and dried at a temperature of 200℃ to solidify the silver paste. The main grid silver electrode 2 and the overlapping point 3 are formed on the back of the battery cell 1. The upper surfaces of the main grid silver electrode 2 and the overlapping point 3 are flush. There are a total of 16 main grid silver electrodes 2 with a printing width of 35μm. The printing length of the overlapping point 3 is 400μm and the width is 150μm. The printing height of the main grid silver electrode 2 and the overlapping point 3 is 3.5μm.

[0039] Step 2: Fabrication of the back-side sub-gate non-silver metal electrode 4

[0040] (1) Take the battery cell 1 with the back side facing up after the preparation of the back main grid silver electrode 2, and print the nickel-coated copper powder paste on the back side of the battery cell 1 by screen printing process. The wet weight of the nickel-coated copper powder paste is 50mg / piece, of which the total mass of nickel-coated copper powder accounts for 92% (nickel is 20% and copper is 72%), and the rest is composed of organic solvent, glass powder and inorganic additives (the organic solvent is 3.3% of alcohol ester dodecyl and 3.3% of diethylene glycol butyl ether acetate, 1% of glass powder, and the inorganic additives are 0.2% of titanium dioxide powder and 0.2% of silicon powder).

[0041] (2) The battery cell 1 is fed into a chain drying oven at a drying temperature of 200°C to solidify the nickel-coated copper powder slurry and form a non-silver metal electrode 4 on the back of the battery cell 1. The non-silver metal electrode 4 is a "core-shell structure" and is made of copper powder wrapped in a single metal film. There are 220 non-silver metal electrodes 4 in total, with a printing width of 12μm and a printing height of 7μm. The non-silver metal electrode 4 burns through the aluminum oxide film and silicon nitride film on the surface of the battery cell 1 and enters the interior of the battery cell 1.

[0042] Step 3: Prepare the back-side photocurable adhesive layer 5

[0043] (1) Take the battery cell 1 with the back side facing up after the preparation of the non-silver metal electrode 4 on the back side, and print a layer of photocurable adhesive (Shenzhen Xinjiayi Technology Co., Ltd., model: 851X) on the non-silver metal electrode 4 using screen printing process. The wet weight of the photocurable adhesive is 90mg / piece.

[0044] (2) Place the battery cell 1 into a UV curing oven and cure it under ultraviolet light (35W / cm²). 2 After irradiation for 45 seconds, the photocurable adhesive is fully cured to form photocurable adhesive layer 5. The natural light transmittance of photocurable adhesive layer 5 is 98%. The printed linewidth of photocurable adhesive layer 5 is larger than that of the non-silver metal electrode 4 of the sub-gate. The linewidth of photocurable adhesive layer 5 is 150μm and the printing height of photocurable adhesive layer 5 is 10μm.

[0045] Step 4: Fabrication of the front-side main gate silver electrode 2

[0046] (1) Take the battery cell 1 with the back composite electrode already prepared, with the front side facing up, and print silver paste on the front side of the battery using screen printing process. The wet weight of the silver paste is 10mg / cell, of which silver accounts for 90% by mass, and the rest is composed of organic solvent, glass powder and inorganic additives (7% organic solvent, 2% glass powder, 1% inorganic additives, the organic solvent is pentaerythritol triacrylate, and the inorganic additives are 0.5% aluminum powder and 0.5% silicon powder).

[0047] (2) The battery cell 1 is fed into a chain drying oven and dried at 200°C to solidify the silver paste and form the main grid silver electrode 2 and the overlap point 3 on the front of the battery. There are 16 main grid silver electrodes 2 in total. The printing width of the main grid silver electrode 2 is 35μm. The length of the overlap point 3 is 400μm and the width is 100μm (greater than the width of the sub-grid). The printing height of the main grid silver electrode 2 and the overlap point 3 is 3.5μm.

[0048] Step 5: Fabrication of the front-side sub-gate non-silver metal electrode 4

[0049] (1) Take the battery cell 1 with the main grid silver electrode 2 already prepared, with the front side facing up, and print the nickel-coated copper powder paste on the front side of the battery cell 1 by screen printing process. The wet weight of the nickel-coated copper powder paste is 45mg / piece, of which the total mass of nickel-coated copper powder accounts for 92% (nickel is 20% and copper is 72%), and the rest is composed of organic solvent, glass powder and inorganic additives (the organic solvent is 3.3% of alcohol ester dodecyl and 3.3% of diethylene glycol butyl ether acetate, 1% of glass powder, and the inorganic additives are 0.2% of titanium dioxide powder and 0.2% of silicon powder).

[0050] (2) The battery cell 1 is fed into a chain drying oven and the drying temperature is 200°C to solidify the nickel-coated copper powder slurry and form a non-silver metal electrode 4 on the front side of the battery cell 1. All non-silver metal electrodes 4 are overlapped with the overlap point 3. There are a total of 220 non-silver metal electrodes 4. The printing width of the non-silver metal electrodes 4 is 10μm and the printing height of the non-silver metal electrodes 4 is 8μm.

[0051] Step 6: Prepare the front-side photocurable adhesive layer 5

[0052] (1) Take the battery cell 1 with the front side of the non-silver metal electrode 4 already prepared, with the front side facing up, and print a layer of photocurable adhesive on the surface of the non-silver metal electrode 4 using screen printing process. The wet weight of the photocurable adhesive is 90 mg / piece.

[0053] (2) Place the battery cell 1 into a UV curing oven and cure it under ultraviolet light (35W / cm²). 2 After irradiation for 45 seconds, the photocurable adhesive fully cures to form photocurable layer 5. The printed linewidth of photocurable layer 5 is larger than that of the non-silver metal electrode 4 of the sub-grid, which is 150 μm. Sintering enables the photocurable adhesive on the front side of the solar cell 1 to fully cure and form photocurable layer 5, thus forming a complete composite electrode structure on the front side of the solar cell 1. It also enables the non-silver metal electrode 4 of the sub-grid on the front and back sides of the solar cell 1 to form good ohmic contact with the solar cell 1, while enhancing the bonding strength between the silver electrode 2 of the main grid and the solar cell 1.

[0054] Comparative Example 1:

[0055] Composite electrode cell structure:

[0056] The solar cell is used to prepare TOPCon cells. The composite electrode structure of the crystalline silicon solar cell includes a solar cell with an aluminum oxide film layer and a silicon nitride layer covering the top and bottom, and grid lines respectively disposed on the top and bottom surfaces of the solar cell. The grid lines include multiple main grid electrodes and multiple sub-grid electrodes. The multiple main grid electrodes are parallel and spaced apart, and the multiple sub-grid electrodes are parallel and spaced apart. The multiple main grid electrodes and multiple sub-grid electrodes are distributed in a mesh structure.

[0057] Step 1: Fabrication of the back-side main gate silver electrode

[0058] (1) Methods for preparing solar cells:

[0059] The battery cell was prepared according to steps (1) to (4) in Example 1 of the patent “An N-type TOPCon battery and its preparation method” (Publication No.: CN113611756A).

[0060] (2) With the back side facing up, silver paste is printed on the back of the 182mm×210mm battery cell by screen printing. The wet weight of the silver paste is 9mg / cell, of which silver accounts for 90% of the mass, and the remainder consists of organic solvent, glass powder and inorganic additives (7% organic solvent, 2% glass powder, 1% inorganic additives, the organic solvent is pentaerythritol triacrylate, and the inorganic additives are 0.5% aluminum powder and 0.5% silicon powder).

[0061] The solar cells are fed into a chain drying oven at a drying temperature of 200°C to solidify the silver paste and form the main grid silver electrode on the back of the solar cell. There are 16 main grid silver electrodes, with a printing width of 35μm and a printing height of 3.5μm.

[0062] Step 2: Fabrication of the back-side sub-gate silver electrode

[0063] (1) Take the battery cell with the back main grid silver electrode prepared, with the back side facing up, and print silver paste on the back side of the battery cell by screen printing process; the wet weight of the silver paste is 50mg / piece, the silver mass accounts for 91%, and the rest is composed of organic solvent, glass powder and inorganic additives (6% organic solvent, 2% glass powder, 1% inorganic additives, the organic solvent is pentaerythritol triacrylate, and the inorganic additives are 0.5% aluminum powder and 0.5% silicon powder).

[0064] (2) The battery cells are fed into a chain drying oven at a drying temperature of 200°C to solidify the silver paste and form a sub-grid silver electrode on the back of the battery. There are a total of 220 sub-grid silver electrodes, with a printing width of 12μm and a printing height of 7μm.

[0065] Step 3: Fabrication of the front-side main gate silver electrode

[0066] (1) Take the battery cell with the back sub-grid silver electrode prepared, with the front side facing up, and print silver paste on the front side of the battery through screen printing process. The wet weight of the silver paste is 9mg / cell, the silver content is 90%, and the rest is composed of organic solvent, glass powder and inorganic additives (7% organic solvent, 2% glass powder, 1% inorganic additives, the organic solvent is pentaerythritol triacrylate, and the inorganic additives are 0.5% aluminum powder and 0.5% silicon powder).

[0067] (2) The battery cells are fed into a chain drying oven and the drying temperature is 200℃ to solidify the silver paste and form the main grid silver electrode on the front of the battery. There are 16 main grid silver electrodes in total. The printing width of the main grid silver electrode is 35μm and the printing height of the main grid silver electrode is 3.5μm.

[0068] Step 4: Fabrication of the front-side sub-gate silver electrode

[0069] (1) Take the battery cell with the front main grid silver electrode prepared, with the front side facing up, and print silver paste on the front side of the battery through screen printing process. The wet weight of the silver paste is 45mg / cell, the silver mass accounts for 91%, and the rest is composed of organic solvent, glass powder and inorganic additives (6% organic solvent, 2% glass powder, 1% inorganic additives, the organic solvent is pentaerythritol triacrylate, and the inorganic additives are 0.5% aluminum powder and 0.5% silicon powder).

[0070] (2) The battery cells are fed into a chain drying oven at a drying temperature of 200°C to solidify the silver paste and form a sub-grid silver electrode on the front of the battery. There are a total of 220 sub-grid silver electrodes. The printing width of the sub-grid silver electrode is 10μm and the printing height of the sub-grid silver electrode is 8μm.

[0071] Step 5: Sintering

[0072] The solar cells are fed into a high-temperature sintering furnace and sintered at 780°C. Sintering can solidify the front sub-grid silver electrode and also enable the sub-grid silver electrodes on the front and back sides of the solar cell to form good ohmic contact with the solar cell, while enhancing the bonding strength between the front and back main grid silver electrodes and the solar cell.

[0073] The silver mass of the TOPCon cells prepared in Example 1 and Comparative Example 1 was calculated, and the photoelectric conversion efficiency of the cells was tested using an IV tester under the following conditions (Standard Test Conditions (STC): irradiance 1000W / m², spectral distribution AM1.5G, cell temperature 25℃). Table 1 shows the comparison of the wet weight of silver paste, silver mass and cell efficiency of the cells in Comparative Example 1 and Example 1.

[0074] Table 1. Comparison of wet weight of silver paste and silver mass with cell efficiency of Comparative Example 1 and Example 1

[0075]

[0076] As can be seen, the silver mass of the battery structure prepared in Example 1 of the present invention is 18 mg / piece, which is 82% less than the silver mass of the battery prepared in Comparative Example 1 (conventional battery) which is 103 mg / piece. This significantly reduces the metal cost of the battery, while the battery efficiency of Example 1 is comparable to that of Comparative Example 1 (conventional battery).

[0077] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A novel composite electrode for crystalline silicon solar cells, characterized in that, The battery cell (1) includes an alumina film layer, a silicon nitride film layer, and grid lines on the surface of the battery cell (1). The grid lines include multiple main grids and multiple sub-grids. The multiple main grids are parallel and spaced apart, and the multiple sub-grids are parallel and spaced apart. The multiple main grids and multiple sub-grids are distributed in a mesh structure. Each main grid includes a main grid silver electrode (2) and multiple pairs of overlapping points (3). The multiple pairs of overlapping points (3) are distributed along the direction of the main grid silver electrode (2). Each pair of overlapping points (3) is connected to the main grid silver electrode (2). The electrodes are distributed on both sides of the main grid silver electrode (2), and each pair of the overlapping points (3) is connected to the main grid silver electrode (2). Each sub-grid includes multiple sub-grid non-silver metal electrodes (4). Each sub-grid non-silver metal electrode (4) is embedded in the surface of the cell (1). The end of the sub-grid non-silver metal electrode (4) near the main grid silver electrode (2) is connected to an overlapping point (3). The surface of each sub-grid non-silver metal electrode (4) is covered with a photocurable adhesive layer (5).

2. A method for preparing a novel composite electrode for crystalline silicon solar cells, characterized in that, For the preparation of the novel crystalline silicon solar cell composite electrode according to claim 1, grid lines and a photocurable adhesive layer (5) are prepared on the surface of the solar cell (1), and the specific steps are as follows: S1. Print silver paste on the surface of the battery cell (1); dry the silver paste on the battery cell (1) to form the main grid silver electrode (2) and the overlap point (3). S2. Take the battery cell (1) prepared in S1 and print non-silver metal-coated copper powder paste on the surface of the battery cell (1); dry the non-silver metal-coated copper powder paste on the battery cell (1) to form the sub-gate non-silver metal electrode (4). S3. Take the battery cell (1) prepared in S2 and print a photocurable adhesive on the surface of the non-silver metal electrode (4) of the sub-gate; sinter the battery cell (1) with UV light to form the photocurable adhesive layer (5) on the surface of the non-silver metal electrode (4).

3. The method for preparing a novel crystalline silicon solar cell composite electrode according to claim 2, characterized in that, In step S1, the size of the battery cell (1) is (180~184) mm × (200~220) mm.

4. The method for preparing a novel crystalline silicon solar cell composite electrode according to claim 2, characterized in that, In step S1, the printing width of the main grid silver electrode (2) is 20~50μm, the printing length of the overlap point (3) is 100~2000μm and the width is 50~500μm, the printing height of the main grid silver electrode (2) and the overlap point (3) is 2~5μm, the number of main grid silver electrodes (2) is 12~20, and the wet weight of the printed silver paste is 8~15mg / piece.

5. The method for preparing a novel crystalline silicon solar cell composite electrode according to claim 2, characterized in that, In step S2, the width of the sub-gate non-silver metal electrode (4) is 10~30μm, and the printing height of the sub-gate non-silver metal electrode (4) is 2~10μm.

6. The method for preparing a novel crystalline silicon solar cell composite electrode according to claim 2, characterized in that, In step S2, there are a total of 180 to 300 non-silver metal electrodes (4) for the sub-gate, and the wet weight of the non-silver metal copper-coated powder slurry is 35 to 80 mg / piece.

7. The method for preparing a novel crystalline silicon solar cell composite electrode according to claim 2, characterized in that, In step S3, the transmittance of the photocurable adhesive layer (5) to natural light is 97-99%.

8. The method for preparing a novel crystalline silicon solar cell composite electrode according to claim 2, characterized in that, In step S3, the printing width of the photocurable adhesive layer (5) is 80~500μm, the printing height is 3~20μm, the wet weight of the photocurable adhesive is 80~200mg / piece, and the UV light irradiation time is 5~90s.

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