A method for preparing a conductive grid of a photovoltaic cell based on gel plating

Abstract

This invention discloses a method for preparing a conductive grid for photovoltaic cells based on gel electroplating, comprising the following steps: S1. Patterned opening step: Micropores with a preset pattern are formed on the non-conductive area of ​​the photovoltaic cell substrate to be processed using laser processing, exposing the underlying conductive functional area; S2. Gel electrolyte application step: An electrolyte containing target metal ions is mixed with a gelling agent to form a paste or gel-like electrolyte, and the gel electrolyte is precisely filled and attached to the micropores and the preset grid pattern area formed in step S1 by patterned printing; S3. Electrochemical deposition step: An external electric field is applied to the substrate after step S2. By combining laser patterned opening with patterned printed gel electrolyte, the production process is simplified, equipment costs and environmental pollution are reduced, while the accuracy, performance consistency and durability of the photovoltaic cell conductive grid are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic cell manufacturing, in particular to a photovoltaic cell conductive grid preparation method based on gel plating. BACKGROUND

[0002] A photovoltaic cell is a device that directly converts solar energy into electrical energy through photovoltaic effect. The conductive metal grid on the surface of the photovoltaic cell plays a key role in collecting and transmitting photo-generated current. The conductivity, aspect ratio and shading area of the grid directly affect the conversion efficiency and cost of the cell.

[0003] In the field of photovoltaic cell conductive grid preparation, traditional technology generally relies on immersion plating process to complete the deposition of the metal conductive layer, that is, the photovoltaic cell substrate is immersed in a liquid electrolyte containing metal ions, and the metal ions are reduced and deposited on the substrate surface to form a grid line through power supply. However, this process has some defects: first, the processing flow is long, the substrate needs to go through multiple processes such as pretreatment, plating, and post-cleaning, and in order to ensure the uniformity and deposition effect of the electrolyte, additional temperature control, stirring and filtration steps are often required, resulting in a significant extension of the production cycle; second, the equipment investment cost is high, not only large electrolyte tanks, waste liquid treatment systems and complex hanger tooling are required, but also special equipment needs to be customized for different sizes of photovoltaic substrates, which has poor compatibility and high initial investment; third, the environmental burden is heavy, a large amount of liquid electrolyte is prone to volatilization and leakage during use, and the generated heavy metal-containing waste liquid needs to be treated at a high cost, and the overall immersion method will cause excessive consumption of electrolyte, resulting in low resource utilization. In addition, immersion plating cannot accurately control the deposition of metal ions only in the preset grid line area, which is prone to side reactions in non-target areas, affecting the accuracy and performance consistency of the conductive grid, and increasing the cost of subsequent trimming process.

[0004] Therefore, a photovoltaic cell conductive grid preparation method based on gel plating is proposed to solve the problems raised in the above background. SUMMARY

[0005] The present application aims to provide a photovoltaic cell conductive grid preparation method based on gel plating to solve the problems of long process, high cost, heavy environmental pollution and poor deposition accuracy of the current immersion plating process in the preparation of photovoltaic cell conductive grid as described in the background.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a photovoltaic cell conductive grid preparation method based on gel plating, comprising the following steps:

[0007] S1. Patterned opening step: forming a micro-hole with a preset pattern on the non-conductive area of the photovoltaic cell substrate to be processed by laser processing to expose the underlying conductive functional area;

[0008] S2. Gel electrolyte application step: mix the electrolyte containing target metal ions with a gelling agent to make a paste or gel electrolyte, and fill and adhere the gel electrolyte to the microporous and pre-designed grid pattern area of the substrate formed in step S1 by patterned printing;

[0009] S3. Electrochemical deposition step: apply an external electric field to the substrate treated in step S2, so that the metal ions in the gel electrolyte are reduced under the action of the electric field, thereby depositing a metal conductive layer in the microporous and grid pattern area;

[0010] S4. Gel removal step: clean the substrate after deposition with a cleaning solution to remove residual gel electrolyte on the surface and expose the formed metal conductive structure;

[0011] S5. Surface alloying step: immerse the cleaned substrate in a solution containing tin or silver ions to form an alloy protective layer on the surface of the metal conductive layer through chemical displacement or deposition reaction;

[0012] S6. Post-processing step: dry and cure the substrate treated in step S5 to complete the preparation of the conductive grid.

[0013] Preferably, in step S1, the photovoltaic cell substrate is any one of BC, TOPCon, HJT or HIT structure.

[0014] Preferably, in step S1, the laser used for laser processing is a picosecond laser or a femtosecond laser, and the laser wavelength is 355 nm, 532 nm or 1064 nm. By adjusting the laser power, frequency and scanning speed, micropores with a diameter of 5-50 μm are processed on the passivation layer. The shape, depth and density of the micropores are set according to the design requirements of the conductive grid, and the laser processing parameters can be adjusted to adapt to the passivation layer and film structure of photovoltaic cells of different technical routes.

[0015] Preferably, in step S2, the gel electrolyte is prepared by adding a thickening agent, a gelling agent or a high molecular polymer to an acidic or alkaline electrolyte to form a paste or gel-like fluid with thixotropy; the target metal ions include one or more of .

[0016] Preferably, in step S2, the patterned printing method is 3D printing technology or screen printing technology.

[0017] Preferably, when using 3D printing technology, specifically inkjet printing technology of drop-on-demand or LIFT printing technology based on laser-induced forward transfer, the gel electrolyte is directly printed on the substrate in a preset grid pattern by controlling the movement path of the printing head and the amount of gel extrusion.

[0018] Preferably, when using screen printing technology, the gel electrolyte is scraped through the screen holes and attached to the surface of the substrate using a screen with a preset grid pattern.

[0019] Preferably, in step S3, the method of applying an external electric field for electrochemical deposition is as follows: the photovoltaic cell substrate itself is used as the cathode, and an inert electrode is used as the anode to form a loop with the gel electrolyte; the external electric field is applied by contact power supply or non-contact induction power supply; the electrochemical deposition uses direct current voltage or pulse voltage, with a voltage of 0.5V to 5V and a current density of 0.5ASD to 10ASD; the deposition time is 10 seconds to 300 seconds.

[0020] Preferably, in step S4, the cleaning liquid is deionized water, warm water or weakly acidic / alkaline aqueous solution, and the cleaning method is spraying, soaking or ultrasonic cleaning.

[0021] Preferably, in step S5, the surface treatment is chemical tin immersion or chemical silver immersion treatment, specifically: the substrate with conductive grid is immersed in a chemical plating solution containing tin ions or silver ions to form a tin plating layer or a silver plating layer on the surface of the metal conductive grid.

[0022] Compared with the prior art, the present application has the following advantages: the method for preparing a conductive grid for a photovoltaic cell based on gel plating simplifies the production process, reduces equipment costs and environmental pollution, and improves the precision, performance consistency and durability of the conductive grid for the photovoltaic cell. The specific contents are as follows:

[0023] Firstly, the present application directly applies the gel electrolyte to the preset area by using pattern printing after laser patterning, without the complex pretreatment and subsequent trimming process in the traditional process, greatly simplifying the operation steps. At the same time, the use of gel electrolyte reduces the dependence on additional links such as temperature control and stirring, effectively shortens the production cycle and improves the production efficiency. Moreover, this method does not require large electrolyte tanks and supporting complex hanger tooling, and only laser processing equipment, pattern printing equipment and simple electrochemical deposition devices are needed to complete production, reducing the initial investment cost of equipment. Furthermore, by adjusting the laser processing parameters and printing patterns, different sizes and different technical routes of photovoltaic cell substrates can be easily adapted, and the equipment compatibility is stronger, avoiding the problem of frequent replacement of special equipment due to substrate differences.

[0024] Secondly, the gel electrolyte is in paste or gel form, not easy to volatilize and leak, reducing the generation of heavy metal-containing waste liquid from the source, reducing the cost of waste liquid treatment, and reducing the pollution to the environment. In addition, the gel electrolyte is precisely filled in the target area by graphic printing, avoiding the excessive consumption of electrolyte in the traditional overall soaking mode, greatly improving the utilization rate of metal ions and other resources, and realizing a more environmentally friendly and economical production process. At the same time, by means of laser processing to form an accurate microporous pattern, combined with the graphic printing technology to accurately apply the gel electrolyte to the preset grid line pattern area, the electrochemical deposition process is only carried out in the target area, effectively avoiding the side reaction of metal ions in the non-target area, and ensuring the position accuracy of the metal conductive layer deposition. Moreover, the gel electrolyte system is stable, which can provide a uniform ion environment for the electrochemical deposition process, which is conducive to forming a metal conductive layer with uniform structure and stable performance, thereby improving the overall performance consistency of the conductive grid.

[0025] Finally, by means of surface alloying, a layer of tin or silver alloy protective layer is formed on the surface of the metal conductive layer, which can improve the oxidation resistance, corrosion resistance and wear resistance of the conductive grid, reduce the influence of the external environment on its conductivity, prolong the service life of the photovoltaic cell, and improve its long-term working reliability. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a process flow structure schematic diagram of the present application; DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0028] Example 1: Preparation of conductive grid for HJT structure photovoltaic cell (3D printing-inkjet printing technology)

[0029] (I) Material and equipment preparation

[0030] In this embodiment, the HJT (heterojunction) structure photovoltaic cell substrate is taken as the processing object, and the surface of the substrate is provided with a transparent conductive oxide layer (TCO layer) and a passivation layer (non-conductive area) in sequence. The lower layer is a conductive functional area (silicon-based conductive layer). Before the experiment, the substrate is pretreated: ultrasonic cleaning with deionized water for 10 minutes to remove surface oil and dust, and then dried in an 80°C constant temperature drying box for 30 minutes to ensure that the substrate surface is clean and dry.

[0031] The materials and equipment used in the experiment include: picosecond laser (wavelength 355 nm), inkjet 3D printer (resolution 1200 dpi), electrochemical workstation, acidic electrolyte (copper sulfate concentration 0.5 mol / L) containing , gelling agent (hydroxypropyl methyl cellulose, content 5 wt%), deionized water, electroless plating solution containing silver ions (silver nitrate concentration 0.1 mol / L), constant temperature drying oven.

[0032] (II) Specific preparation steps

[0033] 1. Patterning hole step (S1)

[0034] The pretreated HJT substrate is fixed on the laser processing platform, and the picosecond laser parameters are set as follows: laser power 15 W, frequency 50 kHz, and scanning speed 100 mm / s. According to the preset design requirements of the conductive grid (grid line width 50 μm, pitch 2 mm), the laser is controlled to scan along the preset path by the laser processing system, and circular micropores with a diameter of 10 μm and a depth of 5 μm are processed on the passivation layer of the substrate. The micropore array corresponds to the subsequent grid pattern, ensuring that each micropore accurately exposes the underlying TCO conductive functional area. After processing, compressed air is used to blow the surface of the substrate to remove the residues generated by laser processing.

[0035] 2. Gelling electrolyte application step (S2)

[0036] First, the gelling electrolyte is prepared: the acidic electrolyte containing is mixed with hydroxypropyl methyl cellulose at a mass ratio of 95:5, stirred at 50°C for 30 minutes, and a uniform and thixotropic paste-like gelling electrolyte (viscosity ) is formed. Then, the gelling electrolyte is loaded into the cartridge of the inkjet 3D printer, and the printing parameters are set as follows: print head temperature 25°C, extrusion pressure 0.3 MPa, and nozzle diameter 50 μm. The preset grid pattern data is imported into the printer control system, and the print head is controlled to move along the surface of the substrate, accurately filling the gelling electrolyte into the micropores formed in step S1, and printing a gelling electrolyte layer with a thickness of 20 μm on the surface of the substrate according to the grid pattern, ensuring that the gelling electrolyte is tightly attached to the micropores and the surface of the substrate without leakage and overflow.

[0037] 3. Electrochemical deposition step (S3)

[0038] Construction of the electrochemical deposition system: take the HJT photovoltaic cell substrate as the cathode (the conductive functional area as the cathode conductive layer), take the graphite inert electrode as the anode, and place the two in parallel in the reaction tank containing the above-mentioned gel electrolyte, with an electrode spacing of 5 cm, forming a closed loop. An external electric field is applied using an electrochemical workstation, selecting a direct current voltage mode, with a voltage of 2 V, a current density of 5 ASD, and a deposition time of 60 seconds. Under the action of the electric field, the gel electrolyte migrates to the cathode (substrate conductive functional area) and undergoes a reduction reaction , depositing a uniform copper metal conductive layer in the micropores and grid pattern area. The thickness of the conductive layer is regulated by the deposition time and current density.

[0039] 4. Gel removal step (S4)

[0040] After deposition, the substrate is removed and cleaned with deionized water spray (spray pressure 0.2 MPa, temperature 25°C) for 5 minutes to remove unreacted residual gel electrolyte on the surface of the substrate. Then the substrate is immersed in deionized water for ultrasonic cleaning for 3 minutes (power 300 W) to further remove gel impurities in the micropores. Finally, the substrate surface is blown dry with compressed air, and the complete copper metal conductive grid structure is exposed on the substrate surface.

[0041] 5. Surface alloying step (S5)

[0042] The cleaned substrate is immersed in a chemical plating solution containing silver ions, with a plating solution temperature of 40°C, a pH value of 5.5, and an immersion time of 10 minutes. Through a chemical displacement reaction , a 0.5 μm thick silver alloy protective layer is formed on the surface of the copper conductive grid, which can improve the corrosion resistance and conductivity of the conductive grid. After immersion, the substrate is removed and the surface residual plating solution is washed with deionized water, and then dried.

[0043] 6. Post-processing step (S6)

[0044] The substrate after surface alloying treatment is placed in a constant temperature drying oven at 120°C for 60 minutes to fully combine and solidify the silver alloy protective layer with the copper conductive layer, and finally the preparation of the HJT structure photovoltaic cell conductive grid is completed.

[0045] Example 2: Preparation of conductive grid based on TOPCon structure photovoltaic cell (screen printing technology)

[0046] (I) Material and equipment preparation

[0047] This embodiment uses a TOPCon (tunneling oxide passivated contact) structure photovoltaic cell substrate. The non-conductive area on the surface of this substrate is a silicon nitride passivation layer, and the underlying conductive functional area is a doped polycrystalline silicon layer. The substrate pretreatment method is the same as in Example 1: ultrasonic cleaning with deionized water and drying at 80°C.

[0048] Experimental materials and equipment included: a femtosecond laser (wavelength 1064nm), a screen printing machine (400 mesh screen), an electrochemical workstation, and other equipment. The alkaline electrolyte (silver nitrate concentration 0.3 mol / L) and gelling agent (polyacrylamide, content...) ), warm water (50℃), tin-containing chemical plating solution (stannous chloride concentration 0.2mol / L), and vacuum drying oven.

[0049] (II) Specific preparation steps

[0050] 1. Graphical hole-making process (S1)

[0051] The pretreated TOPCon substrate was fixed on a laser processing stage, and the femtosecond laser parameters were set as follows: laser power 20W, frequency 30kHz, and scanning speed 80mm / s. Based on the conductive grid design requirements (grid line width 80μm, spacing 3mm), square micropores with a diameter of 20μm and a depth of 8μm were processed. The micropore positions corresponded to the grid line direction to ensure complete penetration of the passivation layer and exposure of the underlying doped polysilicon conductive region. After processing, laser processing debris was removed from the substrate surface using a vacuum suction pen.

[0052] 2. Gel electrolyte application step (S2)

[0053] Preparation of gel electrolyte: [The text abruptly ends here, likely due to an incomplete sentence or missing information.] An alkaline electrolyte and polyacrylamide were mixed at a mass ratio of 92:8 and stirred at 60°C for 40 minutes to form a gel-like electrolyte with moderate viscosity. Select a screen printing plate with a preset grid pattern (the screen openings match the grid pattern, with an opening rate of 30%), fix it on the screen printing machine, adjust the distance between the printing plate and the substrate to 2mm, the squeegee pressure to 0.4MPa, and the squeegee speed to 50mm / s. Apply the gel electrolyte evenly to the printing plate, start the printing machine, and use the squeegee to squeegee the gel electrolyte through the screen openings, precisely filling the micropores of step S1, forming a 30μm thick grid pattern gel layer on the substrate surface. After printing, allow it to stand for 5 minutes to ensure stable adhesion of the gel electrolyte.

[0054] 3. Electrochemical deposition step (S3)

[0055] Building deposition system: TOPCon substrate as cathode (doped polysilicon layer as conductive layer), platinum sheet as anode, electrode spacing 8 cm, external electric field is applied by non-contact inductive power supply. Set pulse voltage mode by electrochemical workstation: voltage 3 V, pulse frequency 100 Hz, duty cycle 50%, current density 8 ASD, deposition time 120 seconds. Under the action of pulse electric field, Reduction deposition on the surface of the cathode Form a dense silver metal conductive layer with a thickness of about 25 μm in the micropore and grid line area.

[0056] 4. Gel removal step (S4)

[0057] After deposition, the substrate is soaked in warm water at 50°C for 10 minutes to soften the residual gel electrolyte; then the substrate surface is rinsed by spraying (warm water, pressure 0.15 MPa), and then ultrasonic cleaning (power 200 W, warm water environment) is performed for 5 minutes to completely remove the gel residue; finally, the substrate is dried with nitrogen to obtain a silver metal conductive grid prototype.

[0058] 5. Surface alloying step (S5)

[0059] The substrate is immersed in a chemical plating solution containing tin ions, the plating solution temperature is controlled at 50°C, the pH value is 4.0, and the immersion time is 15 minutes. A 1 μm thick tin alloy protective layer is formed on the surface of the silver conductive grid through chemical deposition reaction, which improves the welding performance and weather resistance of the grid. After immersion, the substrate is rinsed with deionized water to remove the residual plating solution on the surface.

[0060] 6. Post-processing step (S6)

[0061] The substrate is placed in a vacuum drying oven and dried at 100°C and a vacuum degree of -0.09 MPa for 90 minutes to complete the curing and stabilization treatment of the conductive grid, obtaining a conductive grid for TOPCon structure photovoltaic cell.

[0062] Example 3: Preparation of conductive grid based on BC structure photovoltaic cell (LIFT printing technology)

[0063] (I) Material and equipment preparation

[0064] In this example, the BC (back contact) structure photovoltaic cell substrate is used as the research object, the non-conductive area is an aluminum oxide passivation layer, and the conductive functional area is located on the back surface of the substrate. Substrate pretreatment: ultrasonic cleaning with weak alkaline aqueous solution (pH value 8.0) for 15 minutes to remove the surface oxide layer, and then drying at 90°C for 40 minutes.

[0065] Experimental materials and equipment: picosecond laser (wavelength 532 nm), 3D printer based on laser-induced forward transfer (LIFT), electrochemical workstation, chemical plating solution containing tin ions The following are required: acidic electrolyte (zinc chloride concentration 0.4mol / L), gelling agent (polyvinyl alcohol, content 6wt%), weakly acidic aqueous solution (pH value 5.0), chemical plating solution containing silver ions, and hot air dryer.

[0066] (II) Specific preparation steps

[0067] 1. Graphical hole-making process (S1)

[0068] The picosecond laser parameters were set as follows: power 18W, frequency 40kHz, and scanning speed 90mm / s. Diamond-shaped micropores with a diameter of 15μm and a depth of 6μm were fabricated on the alumina passivation layer on the back side of the BC substrate. The micropore array was matched with the back-side grid pattern to ensure exposure of the underlying conductive functional area. After fabrication, the substrate surface was cleaned alternately with compressed air and deionized water.

[0069] 2. Gel electrolyte application step (S2)

[0070] Preparation of gel electrolyte: [The text abruptly ends here, likely due to an incomplete sentence or missing information.] An acidic electrolyte and polyvinyl alcohol were mixed at a mass ratio of 94:6 and stirred at 55°C for 35 minutes to form a thixotropic gel electrolyte (viscosity). Using LIFT 3D printing technology, with laser energy set at 50mJ, spot diameter at 30μm, and printing speed at 60mm / s, the gel electrolyte was transferred from the feed substrate to the BC substrate surface through laser induction, precisely filling the micropores and printing a grid line gel layer with a thickness of 25μm.

[0071] 3. Electrochemical deposition step (S3)

[0072] Using BC substrate as the cathode and graphite as the anode, a contact-type current-carrying circuit was constructed, applying a DC voltage of 1.5V, a current density of 3ASD, and a deposition time of 80 seconds. Reduced sedimentation A zinc conductive layer with a thickness of 20 μm is formed.

[0073] 4. Gel removal step (S4)

[0074] The substrate was sprayed with a weakly acidic aqueous solution (pH 5.0) at a pressure of 0.25 MPa, followed by ultrasonic cleaning (power 250 W) for 4 minutes to remove gel residue. After drying with nitrogen, a zinc conductive grid was obtained.

[0075] 5. Surface alloying step (S5)

[0076] The substrate is immersed in a chemical plating solution containing silver ions at a temperature of 45°C and a pH of 5.2 for 12 minutes, forming a 0.8μm thick silver alloy protective layer through a displacement reaction.

[0077] 6. Post-processing step (S6)

[0078] Drying with hot air dryer (temperature 110℃, wind speed 2m / s) for 70 minutes to complete the preparation of the conductive grid of the BC structure photovoltaic cell.

[0079] The above examples are only preferred embodiments of the present application, not limiting the present application. In practical application, according to the specific structure (such as BC, TOPCon, HJT, HIT, etc.) and performance requirements of the photovoltaic cell, the parameters of each step can be adjusted:

[0080] Patterned opening step: if the passivation layer of the substrate is thick (such as more than 10μm), the laser power can be increased (such as to 25W), and the scanning speed can be reduced (such as to 50mm / s) to ensure that the micro-holes penetrate the passivation layer; the micro-hole diameter can be adjusted in the range of 5μm-50μm, and the high-density grid line design can select a small aperture of 5μm-15μm to reduce the light shielding rate.

[0081] Gel electrolyte preparation: adjust the acidity and alkalinity of the electrolyte according to the target metal ion type (such as Adapt to acidic system, Adapt to alkaline system), the content of gelling agent can be changed in the range of 3wt%-10wt% to balance the thixotropy and fluidity of the gel to ensure the accuracy during printing or printing.

[0082] Electrochemical deposition step: the deposition voltage can be controlled in the range of 0.5V-5V, the current density in the range of 0.5ASD-10ASD, and the time in the range of 10 seconds-300 seconds, for example, when a thin conductive layer (such as 5μm-10μm) is needed, a low current density (0.5ASD-2ASD) and a short time (10 seconds-60 seconds) can be selected; when a thick conductive layer (such as 20μm-30μm) is needed, the current density can be increased (5ASD-10ASD) and the time can be extended (120 seconds-300 seconds).

[0083] Surface alloying step: according to the application environment, tin or silver protective layer is selected, high temperature and high humidity environment preferentially selects silver alloy (anti-corrosion performance is better), low cost demand scene can select tin alloy; the thickness of the protective layer can be controlled in the range of 0.3μm-1.5μm by adjusting the plating solution concentration (such as silver ion concentration 0.05mol / L-0.2mol / L) and soaking time (5 minutes-20 minutes).

[0084] Through the flexible adjustment of the above parameters, the preparation method of the present application can adapt to photovoltaic cells of different technical routes, and prepare conductive grids with high performance and high reliability, which provides effective support for the conversion efficiency improvement and cost control of photovoltaic cells.

[0085] Although the present application has been described in detail with reference to the foregoing embodiments, the technical solutions recorded in the foregoing embodiments can be modified, or some of the technical features can be replaced by equivalent features, by those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a conductive grid for photovoltaic cells based on gel electroplating, characterized in that, Includes the following steps: S1. Patterned opening step: On the non-conductive area of ​​the photovoltaic cell substrate to be processed, micro-holes with a preset pattern are formed by laser processing to expose the conductive functional area underneath; S2. Gel electrolyte application step: Mix the electrolyte containing the target metal ions with the gelling agent to form a paste or gel electrolyte, and then use a graphic printing method to precisely fill and attach the gel electrolyte to the micropores and the preset grid pattern area formed in step S1. S3. Electrochemical deposition step: An external electric field is applied to the substrate after step S2, causing the metal ions in the gel electrolyte to undergo a reduction reaction under the action of the electric field, thereby depositing a metal conductive layer in the micropore and grid pattern area; S4. Gel removal step: The substrate after deposition is cleaned with a cleaning solution to remove residual gel electrolytes on the surface and expose the formed metal conductive structure. S5. Surface alloying step: Immerse the cleaned substrate in a solution containing tin or silver ions, and form an alloy protective layer on the surface of the metal conductive layer through chemical displacement or deposition reaction. S6. Post-processing step: Dry and cure the substrate after step S5 to complete the preparation of the conductive grid.

2. The method for preparing a photovoltaic cell conductive grid based on gel electroplating according to claim 1, characterized in that: In step S1, the photovoltaic cell substrate is any one of BC, TOPCon, HJT or HIT structures.

3. The method for preparing a photovoltaic cell conductive grid based on gel electroplating according to claim 1, characterized in that: In step S1, the laser used for laser processing is a picosecond laser or a femtosecond laser with a laser wavelength of 355nm, 532nm or 1064nm. By adjusting the laser power, frequency and scanning speed, micropores with a diameter of 5μm-50μm are processed on the passivation layer. The shape, depth and density of the micropores are set according to the design requirements of the conductive grid, and the laser processing parameters can be adjusted to adapt to the passivation layer and film structure of photovoltaic cells with different technical routes.

4. The method for preparing a photovoltaic cell conductive grid based on gel electroplating according to claim 1, characterized in that: In step S2, the gel electrolyte is prepared by adding a thickener, gelling agent, or polymer to an acidic or alkaline electrolyte to form a thixotropic paste or gel fluid; the target metal ions include One or more of them.

5. The method for preparing a photovoltaic cell conductive grid based on gel electroplating according to claim 1, characterized in that: In step S2, the graphic printing method is 3D printing technology or screen printing technology.

6. The method for preparing a photovoltaic cell conductive grid based on gel electroplating according to claim 5, characterized in that: When using 3D printing technology, specifically inkjet printing technology with on-demand dripping or LIFT printing technology based on laser-induced forward transfer, the gel electrolyte is directly printed onto the substrate in a preset grid pattern by controlling the movement path of the print head and the amount of gel extrusion.

7. The method for preparing a photovoltaic cell conductive grid based on gel electroplating according to claim 5, characterized in that: When using screen printing technology, a screen with a preset grid pattern is used to squeegee the gel electrolyte through the screen holes and attach it to the surface of the substrate.

8. The method for preparing a conductive grid for a photovoltaic cell based on gel electroplating according to claim 1, characterized in that: The electrochemical deposition method described in step S3, which involves applying an external electric field, is as follows: the photovoltaic cell substrate itself is used as the cathode, an inert electrode is used as the anode, and a circuit is formed with the gel electrolyte; the external electric field is applied by contact current supply or non-contact inductive current supply; the electrochemical deposition uses a DC voltage or pulse voltage, with a voltage of 0.5V to 5V and a current density of 0.5ASD to 10ASD; the deposition time is 10 seconds to 300 seconds.

9. The method for preparing a photovoltaic cell conductive grid based on gel electroplating according to claim 1, characterized in that: In step S4, the cleaning solution is deionized water, warm water, or a weakly acidic / weakly alkaline aqueous solution, and the cleaning method is spraying, soaking, or ultrasonic cleaning.

10. The method for preparing a photovoltaic cell conductive grid based on gel electroplating according to claim 1, characterized in that: In step S5, the surface treatment is chemical tin immersion or chemical silver immersion treatment, specifically: immersing the substrate with the conductive grid into a chemical plating solution containing tin ions or silver ions to form a tin plating layer or silver plating layer on the surface of the metal conductive grid.

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