Battery piece grid line preparation method and device

Abstract

The invention relates to a battery piece grid line preparation method and device, and aims to reduce material consumption through a transfer printing technology and realize stable and efficient preparation of small-size battery piece grid lines. The method comprises the steps that conductive paste transfer printing layers corresponding to the front face and the back face of a battery piece are manufactured on a transfer printing substrate, and grid line pattern grooves are formed in the transfer printing layers; the grooves are uniformly filled with conductive paste, the conductive paste transfer printing layers on the front face and the back face are accurately attached to the corresponding faces of the battery piece, and synchronous transfer printing of the grid line patterns on the front face and the back face of the battery piece is achieved by applying appropriate pressure and temperature at the same time from top to bottom. By adopting the technical scheme of simultaneous upper and lower transfer printing, the force distribution is effectively balanced, the problem of subfissure of the battery piece is avoided, and the tight fitting degree of the grid line and the surface of the battery piece and the current collection efficiency are remarkably improved. In addition, the invention further provides a battery piece grid line preparation device, the whole preparation process of the battery piece grid line can be completed in one piece of complete machine equipment, and the integration degree of a production line is improved.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a method and device for preparing grid lines of a solar cell. Background Art

[0002] With the increasing global awareness of environmental protection and the active promotion of the country's "dual carbon" goals, building a new power system with new energy as the main body has become an important development direction in the current energy field. As one of the core components of the new energy field, the photovoltaic industry has significantly improved its status and ushered in unprecedented development opportunities. As a key component of the photovoltaic system, the optimization and improvement of the performance of solar cells is directly related to the efficiency and stability of the entire photovoltaic system. At present, industrial production based on single-crystal silicon photovoltaic cells dominates the solar cell market, with its output accounting for more than 90%.

[0003] In solar cells, the electrode grid is a key component that has a vital impact on the performance of the cell. The main function of the electrode grid is to collect the current generated by the photovoltaic effect and conduct it to the external circuit. Therefore, the material selection of the electrode grid and the optimization of its preparation process have become important ways to improve the photoelectric conversion efficiency of solar cells. Metal conductive paste has become one of the most widely used electrode grid materials due to its excellent conductivity and chemical stability.

[0004] However, in the process of preparing the grid lines of photovoltaic cells by forming conductive paste, there are still many technical problems that need to be solved. Although the traditional screen printing technology is mature and the equipment is popular, its accuracy is limited by the aperture of the screen and the printing pressure, and it is difficult to achieve very fine patterns and high-resolution printing. In addition, a lot of waste is generated during the screen printing process, resulting in serious waste of materials. At the same time, the service life of the screen is limited and the price is expensive, which makes the overall cost high. More importantly, the screen printing process is relatively slow and cannot meet the needs of large-scale production, thus affecting production efficiency.

[0005] Specifically, the process of screen printing grid lines includes the steps of front main / sub-grid line printing, back main / sub-grid line printing, drying and sintering. Although these steps can realize the preparation of the front main / sub-grid lines and back main / sub-grid lines of photovoltaic cells, the whole process is cumbersome and inefficient. Each printing requires repositioning and adjusting the screen, which not only increases the complexity of the operation, but also prolongs the production cycle. Therefore, in order to overcome the shortcomings of the existing screen printing technology, it is particularly important to develop a new photovoltaic cell electrode grid line preparation technology with simple process technology, low cost, high production efficiency and high resolution. Summary of the invention

[0006] The purpose of the present application is to provide a method for preparing a grid line of a battery cell, which can realize the production of a micron-level electrode pattern, has a simple preparation process, can significantly reduce material consumption and thus reduce production costs. The purpose of the present application is achieved through the following technical solutions. The method for preparing a grid line of a battery cell includes: Forming conductive paste transfer layers corresponding to the front grid lines and the back grid lines on the transfer substrate respectively, wherein the conductive paste transfer layers include grid line pattern grooves; Filling the gate line pattern groove with a conductive paste; Laminating the conductive paste transfer layer corresponding to the front grid line to the front side of the cell, and laminating the conductive paste transfer layer corresponding to the back grid line to the back side of the cell; Applying pressure on the front and back sides of the cell simultaneously to transfer the conductive paste in the grooves of the grid line pattern to the front and back sides of the cell; The transferred conductive paste is converted into front and back grid lines.

[0007] In one embodiment, making the conductive paste transfer layer includes coating a layer of water-soluble polymer material on the transfer substrate, drying the layer and controlling the thickness to be within the range of 10-50 μm.

[0008] In one embodiment, the transfer substrate is a soft material.

[0009] In one of the embodiments, a gate line pattern groove is formed on the conductive paste transfer layer by embossing using a mold.

[0010] In one embodiment, the gate line pattern includes a first gate line pattern with a groove depth in the range of 10-50 μm and a width in the range of 50-1000 μm and a second gate line pattern with a groove depth in the range of 10-15 μm and a width in the range of 5-50 μm.

[0011] In one of the embodiments, the step of filling the gate line pattern groove with a conductive paste comprises applying a conductive paste on the gate line pattern groove formed by embossing, and scraping off excess conductive paste.

[0012] In one embodiment, during the transfer, the temperature is selected to be in the range of 100-180° C., the applied pressure is in the range of 5-15 MPa, and the duration is selected to be in the range of 2-10 min.

[0013] In one embodiment, the step of transferring the conductive paste in the grid line pattern grooves to the front and back sides of the cell includes first removing the transfer substrate, and then removing the conductive paste transfer layer by liquid dissolution.

[0014] In addition, the present application also provides a cell grid line preparation device, which can implement the above-mentioned cell grid line preparation method in a complete device, thereby improving the integration of the cell production line, and specifically includes: Transfer substrate; A coating component, used for coating a conductive paste transfer layer on the transfer substrate; A hot pressing component, used for forming a grid line pattern groove on the conductive paste transfer layer; A slurry coating component, used for filling the gate line pattern groove with a conductive slurry; A scraping component, used for scraping and removing excess conductive slurry; A transfer component, used to attach the conductive paste transfer layer to the surface of the cell, and transfer the conductive paste in the groove of the grid line pattern to the surface of the cell; A transmission mechanism, the transmission mechanism is used to transmit the battery sheet to the station where the transfer component is located; The method comprises the transfer substrate, the coating component, the hot pressing component, the slurry coating component, the scraping component and the transfer component which correspond to the front grid lines and the back grid lines respectively, and simultaneously transfers the conductive slurry to the front and back sides of the battery cell.

[0015] In one embodiment, the transfer substrate is a round roller type, and the coating component, the hot pressing component, the slurry coating component, and the scraping component are arranged on the round roller in the order of the coating component, and arranged along the rotation direction of the round roller.

[0016] In one embodiment, the cross-section of the transfer substrate is polygonal, including multiple planes, which are respectively arranged on the surface of the transfer substrate in the order of the coating component, the hot pressing component, the slurry coating component, and the scraping component, and the order is the same as the rotation direction of the transfer substrate.

[0017] In one of the embodiments, a moving component is further included, and the moving component synchronously adjusts the heights of the upper and lower transfer substrates of the battery cell.

[0018] In one of the embodiments, a cleaning component is further included, which is arranged before the coating station to clean the surface of the transfer substrate.

[0019] In one embodiment, it further includes a drying component, a cleaning component and a sintering component. The drying component is used to dry the conductive paste, the cleaning component is used to dissolve and remove the conductive paste transfer layer using a solution, and the sintering component is used to sinter the conductive paste.

[0020] In addition, the present application also provides a battery cell, including grid lines on the front and back sides of the battery cell, which is prepared by the aforementioned battery cell grid line preparation method.

[0021] Compared with the prior art, this application has the following beneficial effects: By forming a grid line pattern groove on the conductive paste transfer layer by mold embossing, and accurately controlling the depth and width of the groove (such as a depth in the range of 10-50μm and 5-15μm, and a width in the range of 50-1000μm and 3-50μm), it is possible to easily achieve the production of micron-level electrode patterns, improve the fineness and resolution of the electrode grid lines, and lay a solid foundation for further improving the efficiency of solar cells. The method of the present application simplifies the preparation process by directly making a conductive paste transfer layer on a transfer substrate and completing the transfer of the front and back grid lines at one time, reducing the need for multiple printing and positioning. At the same time, due to the precise filling and scraping of the conductive paste during the transfer process, material waste is effectively reduced.

[0022] By simultaneously transferring the upper and lower parts of the battery cell, the preparation of the front grid lines (including the main grid and the auxiliary grid) and the back grid lines (including the main grid and the auxiliary grid) can be achieved in one step, which greatly improves production efficiency and reduces preparation steps and time costs. The preparation method designed in this application adopts a simplified preparation process. By simultaneously transferring the upper and lower parts of the battery cell, it reduces time investment, reduces production costs, and improves production efficiency. Specifically, PVA can be used as a carrier to help the silver paste fit closely to the battery cell, and dissolve after transfer, so that the conductive paste is transferred to the battery cell. Combined with hot pressing transfer technology, the PVA grooves coated with the conductive paste are closely fitted to the battery cell, and a specific pattern of electrode grid lines is formed after heating and curing. Finally, the PVA is removed by solvent to achieve high efficiency and stability in the one-time preparation of multiple grid lines.

[0023] The cell grid line preparation device of the present application realizes the cell grid line preparation method in a complete device, thanks to the highly integrated preparation device design, including a transfer substrate, a coating component, a hot pressing component, a slurry coating component, a scraping component, a transfer component and a transmission mechanism, etc. It can simplify the current grid line electrode production line, reduce the complexity of the equipment, and realize the full automation from conductive slurry coating to grid line transfer, thereby improving the integration and automation level of the production line, being suitable for industrial production, and facilitating large-scale production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structural flow of the method for preparing the grid line of a battery cell in an embodiment of the present application; Figure 2 This is a schematic diagram of the structure of the grid line distribution of the battery cell in the embodiment of the present application; Figure 3 is a cross-sectional schematic diagram of the shape of the grid line of the battery cell in the embodiment of the present application; Figure 4 This is a schematic diagram of the structure of a battery cell grid line preparation device in one embodiment of the present application; Figure 5 It is a schematic diagram of the structure of a battery cell grid line preparation device in another embodiment of the present application.

[0025] Explanation of the reference numerals: 100, transfer substrate; 200, conductive paste transfer layer; 210, coating component; 300, grid line pattern groove; 310, hot pressing component; 400, conductive paste; 410, coating component; 420, scraping component; 500, grid line; 600, transfer component; 610, drying component; 620, cleaning component; 630, sintering component. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It is to be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some structures related to the present application are shown in the accompanying drawings, rather than all structures. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0027] The terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0028] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0029] Traditionally, the preparation of cell grid lines mostly adopts screen printing technology. Although this technology is mature and widely used, it has problems such as precision limitations, material waste, and low production efficiency, which makes it difficult to meet the current photovoltaic industry's demand for high efficiency, low cost, and large-scale production. Therefore, a new method and device for preparing cell grid lines is explored to achieve accurate production of micron-level electrode patterns, simplify the preparation process, reduce material consumption, and improve production efficiency. This application aims to propose a new method and device for preparing cell grid lines. By combining mold embossing and transfer technology, it can improve preparation efficiency and reduce costs while maintaining high precision and high quality. Please refer to Figure 1 , Figure 1 The present invention is a schematic diagram of the structural flow of a method for preparing a cell grid line. The method for preparing a cell grid line in a preferred embodiment of the present application can significantly reduce material consumption and thus reduce production costs, and can stably form cell grid lines of small size. The method specifically comprises: respectively making conductive paste transfer layers 200 corresponding to front grid lines and back grid lines on a transfer substrate 100, the conductive paste transfer layer 200 comprising grid line pattern grooves 300, filling conductive paste 400 in the grid line pattern grooves 300, laminating the conductive paste transfer layer 200 corresponding to the front grid lines to the front side of the cell, laminating the conductive paste transfer layer 200 corresponding to the back grid lines to the back side of the cell, applying pressure to the front and back sides of the cell simultaneously, transferring the conductive paste 400 in the grid line pattern grooves 300 to the front and back sides of the cell, and converting the transferred conductive paste 400 into front and back grid lines.

[0030] The present application firstly makes conductive paste transfer layers 200 corresponding to the front grid lines and the back grid lines of the cell on the transfer substrate 100. In this step, two transfer substrates 100 are used to make transfer layers respectively. The transfer layers are built with finely designed grid line pattern grooves 300 as carriers of the conductive paste 400. The shapes, sizes and distributions of these grooves are precisely calculated to ensure that the conductive properties and photoelectric conversion efficiency of the final grid line 500 are optimized. Next, the conductive paste 400 is uniformly and fully filled into the grid line pattern grooves 300 using a filling technique. The specific filling method can be selected as needed. This step needs to ensure that the conductive paste 400 can completely cover the bottom and side walls of the grooves, while avoiding unnecessary slurry accumulation outside the grooves, thereby minimizing material waste while ensuring the quality of the grid line 500. The specific method can be the following method of scraping after coating. Subsequently, the prepared front grid line conductive paste transfer layer 200 is precisely bonded to the front of the cell, and the back grid line conductive paste transfer layer 200 is bonded to the back of the cell. In this step, the contact resistance between the grid line 500 and the cell surface is minimized by controlling the positioning accuracy and the degree of bonding, thereby improving the current collection efficiency.

[0031] After the lamination is completed, by applying appropriate pressure and temperature at the same time, the conductive paste 400 in the grid line pattern groove 300 is accurately and evenly transferred to the front and back of the battery cell by utilizing the properties of the transfer substrate 100 and the conductive paste 400. This step can achieve high-precision replication of the grid line pattern, and by optimizing the pressure and temperature conditions, the flow and curing process of the conductive paste 400 can be further controlled to obtain a more uniform and dense grid line 500 structure. Through methods such as heat treatment, the conductive paste 400 after transfer is converted into a front and back grid line with good conductivity and stability, and specifically a conventional sintering method can be adopted. The mechanical strength and durability of the grid line 500 can be improved, and by optimizing the processing conditions, the microstructure and electrical properties of the grid line 500 can be further adjusted to meet the needs of different application scenarios.

[0032] It should be particularly emphasized that the present application adopts the technical solution of simultaneous transfer from top to bottom, which not only realizes the synchronous transfer of the grid line pattern on the front and back of the cell, but also shows technical advantages in the distribution of balancing force, saving production steps and improving the overall preparation efficiency. Through the precisely designed embossing equipment and process parameters, it can be ensured that the pressure on the front and back of the cell is uniform and consistent during the embossing process. This distribution of balancing force not only avoids the problem of hidden cracks in the cell caused by uneven pressure, but also ensures that the grid line 500 is closely attached to the surface of the cell, thereby reducing the contact resistance and improving the current collection efficiency. The distribution of balancing force also helps to reduce the stress concentration phenomenon during the embossing process. The traditional cell grid line preparation process often requires the production of the grid line 500 on the front and back sides separately, which not only increases the production steps and complexity, but also may cause inconsistency between the front and back grid lines during the production process. The process of simultaneous embossing from top to bottom can simultaneously use the links required in multiple steps in one operation, such as alignment, which not only simplifies the production process, but also improves production efficiency and consistency. The innovative process of simultaneous upper and lower stamping has demonstrated significant technical advantages in the preparation of battery cell grid lines. It not only balances the distribution of force and saves production steps, but also improves the overall preparation efficiency.

[0033] Specifically, making the conductive paste transfer layer 200 includes coating a layer of water-soluble polymer material on the transfer substrate 100, drying it and controlling the thickness within the range of 10-50 μm. Water-soluble polymer materials include but are not limited to PVA, PVP, PEG, etc., and the present application is transferred simultaneously on the upper and lower parts of the battery cell. In a specific embodiment, PVA can be used as the main material of the metal paste transfer layer. The solubility of PVA enables the silver paste to be successfully transferred to the battery cell, and the hot pressing transfer technology ensures the close combination of the silver paste and the battery cell to form a stable electrode grid line. The glass transition temperature of PVA is 75-85°C. It slowly changes color and becomes brittle when heated to above 100°C in air. The inherent properties of PVA ensure that it does not rebound and does not change its shape after hot pressing molding. PVA is insoluble in gasoline, kerosene, vegetable oil, benzene, toluene, ethylene dichloride, carbon tetrachloride, acetone, ethyl acetate, methanol, ethylene glycol and other organic solvents. PVA is incompatible and non-reactive with the adhesive in the silver paste. It should be noted that PVA is a specifically selected material and is a relatively preferred technical solution, while other materials with similar properties can also be used as the material of the conductive paste transfer layer 200. The main selection principle is to select a water-soluble polymer material that is incompatible and non-reactive with the substances in the paste, and is selected according to different paste compositions. Under this selection principle, the transfer layer can be removed by an aqueous solution without affecting the distribution of the conductive paste. Combined with the method flow of the present application, the method of removing the transfer layer can be simplified, which is beneficial to improving the integration of the entire process on the production equipment.

[0034] The method of the present application can control the size and shape of the PVA transfer composite conductive grid line through the parameters of the precision hot pressing component 310 (heating temperature, pressure, time, etc.) and the precision mold, and reduce the ohmic loss of the electrode grid line. As a biodegradable and environmentally friendly material, PVA has low environmental harm. The PVA coating that is water-soluble at room temperature can greatly reduce the demoulding cost. The materials and equipment involved are economical and environmentally friendly, and the process cost is low. It is a new technology that can change the current pattern of silver electrode grid line printing for photovoltaic cells.

[0035] The main material of the conductive paste 400 is usually silver paste, because silver has excellent electrical conductivity and chemical stability, and is an ideal choice for preparing high-efficiency photovoltaic cell grid lines. However, with the continuous advancement of technology and cost considerations, conductive pastes 400 formed by other components can also be selected, such as copper paste, aluminum paste, etc., which can also show good electrical conductivity under certain conditions. In the technical solution of the present application, there are no special requirements for the specific materials of the conductive paste 400, which can meet the requirements of different scenarios, and because the present application is to form the conductive paste 400 on the upper and lower surfaces at the same time, it can meet the requirements of using different specific materials independently on the upper and lower surfaces without increasing the complexity of the equipment components, such as using silver paste on the front and aluminum paste on the back. One of the main components of photovoltaic silver paste is an adhesive (phenolic resin, epoxy resin, etc.), which is used to form a stable bond between the silver paste particles and between the particles and the cell. A 20±2μm thick PVA flexible film can be stably prepared on a carrier by a flat coating method. In addition, the technically mature hot pressing component 310 can ensure the precision of the PVA transfer coating after hot pressing molding, and reasonably design the size and shape of the grid line 500. When the PVA needs to be removed, the water solubility of the PVA can be changed by changing the alcoholysis degree of the PVA, blending modification, etc., so that it can be quickly dissolved at room temperature.

[0036] The selection of the transfer substrate 100 has an important influence on the success rate of the entire transfer process. In the present application, the transfer substrate 100 is selected as a soft material, and specifically a soft PET / PI plastic can be selected. The soft material has good elasticity and flexibility, and can closely fit the slight undulations and unevenness of the surface of the battery cell, thereby ensuring that the conductive paste 400 can accurately replicate the preset grid line pattern during the transfer process. The soft substrate can evenly disperse the pressure when under pressure, so that the conductive paste 400 can be evenly distributed on the substrate surface during the transfer process.

[0037] After the conductive paste transfer layer 200 material is completely dried and cured, a gate line pattern groove 300 with a specific shape and size is formed on its surface by using a precisely designed mold through embossing technology. The mold is usually made of high-hardness, high-precision materials to ensure the accuracy and consistency of the grooves during the embossing process. During the embossing process, the mold is in close contact with the conductive paste transfer layer 200, and the conductive paste 400 is guided by the mold to form the required gate line pattern groove 300 by applying appropriate pressure and time. The present application uses a mold to form a gate line pattern groove 300 on the conductive paste transfer layer 200 by embossing. Compared with photolithography or etching processes, using a mold for embossing can greatly simplify the production process. No complicated chemical treatment steps are required. The gate line pattern can be formed by physical means. The mold embossing process is efficient and fast, and the gate line pattern production of a large number of battery cells can be completed in a short time, which can greatly improve production efficiency.

[0038] See also Figure 2 , Figure 3 , Figure 2 Schematic diagram of the structure of the grid line distribution of the battery cell in the embodiment of the present application. The shape and distribution of the grid line of the battery cell finally formed can be adjusted according to the design. For example, the front grid line includes the main grid and the fine grid, and the back grid line only includes the main grid. Figure 3 It is a cross-sectional schematic diagram of the shape of the grid line of the battery cell in the embodiment of the present application. By adopting the imprinting method of the present application, the shape of the grid line 500 electrode can be changed by changing the shape of the imprinting template. For example, an isosceles triangle, rectangle, isosceles trapezoid, ellipse, hexagon, right-angled trapezoid, etc. can be selected.

[0039] In the manufacturing process of photovoltaic cells, the design and production of grid line patterns are crucial and will directly affect the current collection efficiency of the cells. The grid line patterns include a first grid line pattern with a groove depth in the range of 10-50μm and a width in the range of 50-1000μm, and a second grid line pattern with a groove depth in the range of 5-15μm and a width in the range of 3-50μm. By precisely controlling the design of the imprinting mold and the parameters in the imprinting process (such as pressure, time, temperature, etc.), the method of the present application can produce fine grid lines 500 with a groove depth of only 5-15μm and a width of only 3-50μm. The realization of such fine grid lines 500 enables the cells to significantly reduce the shielding of light by the grid lines 500 while maintaining sufficient current collection capabilities, thereby improving the photoelectric conversion efficiency. Compared with the screen printing method, the present application can achieve size control and manufacturing of fine grid lines 500.

[0040] In the manufacturing process of the present application, filling the gate line pattern groove 300 with the conductive paste 400 is a crucial step, which is directly related to the efficiency and stability of the current transmission of the cell. This step can be finely divided into two sub-steps: first, evenly apply a layer of conductive paste 400 on the gate line pattern groove 300 formed by embossing; then, using a scraper or similar tool, scrape off the excess conductive paste 400 on the edge and surface of the groove at a precise angle and force, that is, the step of filling the gate line pattern groove 300 with the conductive paste 400 includes applying the conductive paste 400 on the gate line pattern groove 300 formed by embossing, and scraping off the excess conductive paste 400. By evenly applying the conductive paste 400 on the gate line pattern groove 300, it can be ensured that each groove is fully filled, thereby forming a good conductive channel. Accurate filling helps to reduce the loss of raw materials in the manufacturing process and can avoid the occurrence of failures such as gate disconnection.

[0041] When performing the thermal transfer process, the selection of temperature, pressure and time is crucial. In this application, the temperature is selected in the range of 100-180°C, the applied pressure is in the range of 5-15MPa, and the duration is selected in the range of 2-10min. The process parameters within the above parameter range can ensure good adhesion between the transfer material (such as thermal transfer film) and the transfer substrate 100, while avoiding deformation of the material due to excessive temperature. By accurately controlling the temperature, pressure and duration, the accuracy and integrity of the transfer pattern can be ensured. Under the premise of ensuring the transfer quality, by optimizing the process parameters, the production cycle can be shortened and the production efficiency can be improved.

[0042] In order to further control the shape and size of the gate line 500, the process step of transferring the conductive paste 400 in the gate line pattern groove 300 to the front and back of the cell includes a two-stage processing process. The step of transferring the conductive paste 400 in the gate line pattern groove 300 to the front and back of the cell includes first removing the transfer substrate 100 and then removing the conductive paste transfer layer 200 by liquid dissolution. First, the transfer substrate 100 carrying the conductive paste 400 is removed, and then the conductive paste transfer layer 200 covering the gate line pattern is gently and effectively removed by liquid dissolution. This process can ensure the integrity and positioning accuracy of the conductive paste 400 pattern and avoid displacement or damage that may occur in subsequent processing.

[0043] See also Figure 4 , Figure 5 In addition, the present application also provides a battery cell grid line preparation device, which can implement the aforementioned battery cell grid line preparation method in a complete device, improve the integration and automation level of the battery cell production line, and specifically include: a transfer substrate 100, which serves as a starting carrier for the transfer of the conductive paste 400 and is designed with a high-precision, high-wear-resistant surface, on which a conductive paste transfer layer 200 is prepared, which can ensure uniform coating and precise transfer of the paste.

[0044] The coating component 210 is used to coat the conductive paste transfer layer 200 on the transfer substrate 100, and a layer of the conductive paste transfer layer 200 is uniformly coated on the transfer substrate 100 by using precision coating technology, such as spraying, rolling or slit coating. The hot pressing component 310 is used to form a grid line pattern groove 300 on the conductive paste transfer layer 200, and a fine grid line pattern groove 300 is embossed on the conductive paste transfer layer 200 by precisely controlling the temperature and pressure. This process can ensure the accuracy and consistency of the grid line 500 structure.

[0045] The paste coating component 410 is used to fill the conductive paste 400 in the grid line pattern groove 300. The conductive paste 400 is initially filled in the formed grid line pattern groove 300. The main material of the conductive paste 400 is usually silver paste, because silver has excellent conductivity and chemical stability, and is an ideal choice for preparing high-efficiency photovoltaic cell grid lines. However, with the continuous advancement of technology and cost considerations, conductive pastes 400 formed by other components can also be selected, such as copper paste, aluminum paste, etc.

[0046] The scraping component 420 is used to scrape and remove excess conductive paste 400. A precision scraper or similar tool is used to scrape and remove excess metal paste to ensure that the conductive paste 400 in the groove is completely filled and there is no excess paste outside the groove, thereby ensuring that the size of the gate line 500 after transfer is controllable and the edge is neat.

[0047] The transfer component 600 is used to laminate the conductive paste transfer layer 200 onto the surface of the cell, transfer the conductive paste 400 in the grid line pattern groove 300 to the surface of the cell, and tightly laminate the metal paste transfer layer onto the surface of the cell through precise alignment and appropriate pressure. The transfer component 600 is mainly a moving component, which is used to laminate the conductive paste transfer layer 200 onto the surface of the cell by moving the transfer substrate 100. The movement methods include translation, up and down movement, rotation, etc., and controllable pressure and temperature can also be provided. As long as the method and component can laminate the conductive paste transfer layer 200 onto the surface of the cell, they can be considered as the transfer component 600.

[0048] The transmission mechanism is used to transmit the battery cell to the workstation where the transfer component 600 is located. The transmission mechanism is designed with an efficient and stable transmission path, and can accurately transmit the battery cell (or processed battery cell) to the workstation where the transfer component 600 is located, ensuring the continuity and efficiency of the entire production process. The main method used can be a transmission method compatible with the current existing battery cell production line, such as a belt single-cell transmission method.

[0049] Wherein, including the transfer substrate 100 corresponding to the front grid line and the back grid line respectively, the coating component 210, the hot pressing component 310, the paste coating component 410, the scraping component 420 and the transfer component 600, the conductive paste 400 transfer of the front and back sides of the battery cell is carried out simultaneously. For the front and back sides of the battery cell, there is a completely identical independent component system to carry out the transfer operation of the back grid line with the same process. These two systems are not only independent of each other, but also can work in a highly coordinated manner to ensure that the front and back grid lines 500 transfer are carried out simultaneously without interfering with each other. Through the parallel processing design, the front and back grid lines of the battery cell can be transferred simultaneously, greatly shortening the production cycle. The equipment can make good use of the vertical space, so that the plant space and equipment resources are more fully utilized. In addition, the number and combination of the workstations of the present application are not specifically limited, and the specific method can include multiple workstations arranged according to other automation equipment in the production line, so that the connection can be achieved without adjusting the layout architecture of the current production line automation equipment. The device of the present application is equipped with two sets of independent but synchronously operated transfer substrates 100, coating components 210, hot pressing components 310, slurry coating components 410, scraping components 420 and transfer components 600 corresponding to the front and back sides of the battery cell respectively, and can simultaneously complete the transfer of conductive paste 400 on the front and back sides of the battery cell in a single device.

[0050] See also Figure 4 , Figure 4It is a schematic diagram of the structure of a cell grid line preparation device in one embodiment of the present application, wherein the transfer substrate 100 is a round roller type, and the coating component 210, the hot pressing component 310, the slurry coating component 410, and the scraping component 420 are arranged on the round roller in the order of the coating component 210, the hot pressing component 310, the slurry coating component 410, and the scraping component 420, and arranged along the rotation direction of the round roller. In this embodiment, the transfer substrate 100 adopts a round roller design, which can utilize the continuous rotation characteristics of the round roller to arrange the components used in a series of key processing steps (coating component 210, hot pressing component 310, slurry coating component 410 and scraping component 420) in sequence and compactly along the circumferential direction of the round roller, and follow the rotation direction of the round roller for layout. In the figure, A is the rotation direction, and B is the cell transmission direction. The coating component 210 first contacts the round roller transfer substrate 100, and is responsible for evenly coating a thin layer of conductive paste 400 on its surface. Specifically, a slit coating method can be selected. Then, the hot pressing component 310 uses the preset temperature and pressure conditions to accurately form the required grid line pattern grooves 300 on the conductive paste 400 layer. This process requires a high degree of accuracy and stability. The component can also use a round roller method to emboss the surface of two round rollers at the same surface speed. The changes in structural parameters such as electrode patterns and sizes can be achieved by replacing the template in the hot pressing component 310, which is suitable for battery cells of different designs and has good compatibility. Subsequently, the slurry coating component 410 fills additional conductive paste 400 into these fine grooves, and the flattening component 420 scrapes off excess slurry with the set force and angle, so that the grid line pattern is clearer and filled completely. Finally, the transfer component 600 is used to fit the conductive paste transfer layer 200 to the surface of the cell, and transfer the conductive paste 400 in the grid pattern groove 300 to the surface of the cell. In this way, the round roller transfer substrate 100 only needs to rotate, without moving up and down. The continuous rotation design of the round roller transfer substrate 100 allows each processing step to be seamlessly connected. By arranging each component compactly along the circumferential direction of the round roller, the floor space is effectively saved, making the production line layout more compact and reasonable, and also convenient for daily maintenance and operation.

[0051] See also Figure 5 , Figure 5It is a schematic diagram of the structure of a cell grid line preparation device in another embodiment of the present application. In this embodiment, the cross section of the transfer substrate 100 is a polygon, including multiple planes, which are respectively arranged on the surface of the transfer substrate 100 in the order of the coating component 210, the hot pressing component 310, the slurry coating component 410, and the flattening component 420, and the order is the same as the rotation direction of the transfer substrate 100. In the figure, A is the rotation direction, and B is the cell transmission direction. The transfer substrate 100 is designed to be a polygonal cross-sectional structure, which can make full use of the geometric characteristics of the polygon. The polygonal cross-sectional transfer substrate 100 contains multiple planes, which provide stable working surfaces for each processing component, and can also continuously adjust the workstation by means of rotation, ensuring the continuity and stability of the processing process.

[0052] Specifically, the coating component 210, the hot pressing component 310, the paste coating component 410 and the scraping component 420 are arranged in sequence on each plane of the transfer substrate 100, and the arrangement order is consistent with the direction of the transfer substrate 100 when rotating, so as to ensure the smooth connection and operation of the processing steps. The coating component 210 first acts on a plane of the transfer substrate 100, and evenly coats a layer of conductive paste transfer layer 200. At the next station, the hot pressing component 310 accurately embosses the grid line pattern on the second plane. By replacing the template in the hot pressing component 310, the structural parameters such as the electrode pattern and size can be changed, which is suitable for cells of different designs. The paste coating component 410 fills the conductive paste 400 into the groove of the grid line pattern on the third plane, and the scraping component 420 removes the excess paste with a fine scraping action on the fourth plane, and the transfer station corresponds to the fifth plane. In this way, five operations are performed at five positions at the same time, which can form good continuity. The design of the transfer substrate 100 with a polygonal cross section enables each processing step to be performed simultaneously on different planes, and each processing component is correspondingly arranged on a specific plane of the transfer substrate 100, ensuring the stability and consistency of the processing process. In addition, the polygon is preferably a hexagon, which can provide an extra station position to add other steps (such as cleaning) or facilitate maintenance.

[0053] In a further embodiment, at the coating station, the surface of the transfer substrate 100 is in a horizontal state. In this state, the flat-plate coating method can be used to evenly distribute the slurry and is conducive to the recovery of excess slurry, thereby stably preparing a 20±2μm thick PVA flexible film on the carrier. On the horizontal transfer substrate 100, the flat-plate coating method is used to evenly distribute the slurry. In the horizontal state, the slurry can be more evenly and stably distributed on the transfer substrate 100, avoiding the flow and accumulation of slurry caused by gravity or tilt angle, thereby ensuring the uniformity and consistency of the conductive slurry 400.

[0054] Since the polygon has a plane, the distance between each position and the center of the rotation axis is inconsistent. In this method, a moving component is also included, and the moving component synchronously adjusts the height of the upper and lower transfer substrates 100 of the battery cell. By adjusting the relative height position of the center of the rotation axis, the upper and lower transfer substrates 100 can be pressed and transferred to the battery cell. Other components arranged around can also be provided with corresponding moving components as needed to make room for the movement of the transfer substrates.

[0055] In the conventional screen printing turntable method, only one surface of the grid line 500 can be produced, and due to the difference in size, the main grid and the auxiliary grid need to be screen-printed using different screens respectively, and an additional cell flipping structure is also required. However, the present application can cancel the turntable structure, can only cooperate with the horizontal transmission device, and set relevant components in the vertical space, and realize the imprinting of the upper and lower surfaces at the same time, and can realize the production of the front and back grid line electrodes at the same time, especially can simultaneously produce all the grid lines (including the main grid and the auxiliary grid) on the front and back of the cell. In this specific implementation, the transfer workpiece can be used as an auxiliary component to place the cell on the transfer substrate 100 below. After the imprinting is completed, the suction cup is used to place the cell back on the transmission component, such as a conveyor belt, and transmit it to the subsequent station, such as a suction cup. Buffer stations can be set, including upstream and downstream buffer stations.

[0056] Specifically, a cleaning component is also included, which is arranged before the coating station to clean the surface of the transfer substrate 100. In the cleaning station, a physical brushing method can be used to remove the residue on the surface of the transfer substrate 100. The addition of the cleaning station is an important supplement and optimization of the coating process, which fundamentally improves the quality and efficiency of the coating operation and lays the foundation for producing high-quality products.

[0057] Specifically, it also includes a drying component 610, a cleaning component 620 and a sintering component 630. The drying component 610 is used to dry the conductive paste 400, the cleaning component 620 is used to dissolve and remove the conductive paste transfer layer 200 using a solution, and the sintering component 630 is used to sinter the conductive paste 400. Through these supplementary components, the entire process flow is fully integrated.

[0058] In addition, the present application also provides a battery cell, including grid lines 500 on the front and back sides of the battery cell, which are prepared by the aforementioned battery cell grid line preparation method.

[0059] Specific embodiment: The technical solution of the present application is described in detail with a specific embodiment. In this specific embodiment, PVA is used as the material of the conductive paste transfer layer, and the conductive paste is selected as silver paste. Based on the understanding of photovoltaic silver paste and the study of the new hydrogen bond mechanism in polyvinyl alcohol (PVA) materials, it is found that PVA has no reactivity and weak adhesion with silver paste adhesives and solvents, and can be used as an ideal carrier for transferring silver paste. Please refer to Figure 1 , a layer of PVA is coated on the soft PET / PI plastic, and a layer of 10-50μm PVA coating is obtained after drying at 100-150℃. Using embossing technology, a customized mold is used in a precision hot pressing device to press out the electrode pattern grooves with a depth of 10-50μm and a width of 50 to 500μm required for the main grid line, and a fine grid groove with a height of 10-15μm and a width of 5μm is pressed in the direction perpendicular to the fine grid. On the other hand, another mold is used in a precision hot pressing device to press out the electrode pattern grooves with a depth of 10-50μm and a width of 50 to 500μm required for the back grid line. At the same time, silver paste is applied to the grooves of the two hot-pressed PVAs to fill the grooves tightly. After scraping off the excess silver paste, it is evenly covered on the battery cell, one side is attached to the front grid line / side grid line, and the other side is attached to the back grid line. Due to the adhesion of photovoltaic silver paste to the battery cell, the silver paste is heated to 100-180℃ and a pressure of 5-15MPa is applied for 2-10min for transfer. The upper and lower PI films are torn out, and the silver paste and PVA coating can fit tightly with the battery cell. Then, the PVA coating is often washed with warm water and dissolved, and the silver paste is successfully transferred to the battery cell. After high-temperature sintering, the silver paste forms a specific pattern electrode grid line on the front / back.

[0060] On the basis of the embossing and PVA transfer processes, the upper and lower parts of the battery cell are transferred simultaneously, and the three steps of the above-mentioned screen printing can be achieved in one step, which greatly improves the production efficiency and reduces the production cost. The process of transferring the film is very simple, and it is also very simple to transfer it to the battery cell, which is conducive to industrial production.

[0061] When using the imprinting method, it has the following advantages: the imprinting method can achieve nano-scale pattern preparation, has higher resolution and accuracy than traditional methods, and helps to improve the performance and efficiency of photovoltaic cells. The imprinting method has good reproducibility and can stably prepare high-quality electrode patterns to ensure the stability and reliability of photovoltaic cells. Compared with other micro-nano processing technologies, the imprinting method is low-cost and suitable for large-area preparation, which helps to reduce production costs and improve production efficiency. The imprinting method can realize the preparation of a variety of functional patterns, such as optical structures, surface-enhanced Raman scattering structures, etc., providing more possibilities for the performance optimization of photovoltaic cells. The imprinting method usually does not require the use of organic solvents, has a lower environmental impact, meets the requirements of green manufacturing, and is conducive to sustainable development. By adding the advantages of the nanoimprinting method, the innovation and practicality of the technical solution can be further highlighted, and the superiority and potential of the technical solution in the preparation of photovoltaic cell electrodes can be demonstrated.

[0062] First of all, this preparation process of high-resolution composite silver paste transfer film based on an imprintable polymer material carrier (such as PVA carrier) can achieve micron-level or even nanometer-level electrode patterns, which has higher resolution than traditional screen printing technology and helps to improve the performance and efficiency of photovoltaic cells. Using PVA carrier as a transfer carrier, the preparation process is relatively simple, easy to operate, and suitable for large-scale production. PVA material cost is low, and this method can reduce waste generation, reduce material waste, and thus reduce production costs.

[0063] PVA has no reactivity with silver paste adhesives and solvents and has weak adhesion. It can effectively serve as an ideal carrier for transferring silver paste, which is conducive to the close fit between silver paste and battery cells. Compared with screen printing technology, this method has higher production efficiency, can meet the needs of large-scale production, and improve production efficiency. PVA carrier is often dissolved after washing with warm water, which is environmentally friendly and sustainable, and is conducive to reducing the impact on the environment.

[0064] As can be seen from the foregoing, the present application proposes a new method for preparing grid lines of battery cells, which reduces material consumption through precise transfer technology, thereby effectively reducing production costs, and successfully realizes the stable preparation of grid lines of small-sized battery cells. The specific steps include: first, respectively making conductive paste transfer layers corresponding to the front and back sides of the battery cells on the transfer substrate, these transfer layers are built with grid line pattern grooves, the conductive paste is evenly filled into the grooves, and unnecessary paste accumulation is avoided by controlling the filling method. Next, the conductive paste transfer layers on the front and back sides are precisely fitted to the front and back sides of the battery cells, respectively, and the conductive paste in the grid line pattern grooves is transferred to the surface of the battery cell by applying appropriate pressure and temperature at the same time. Finally, the transferred conductive paste is converted into front and back grid lines with good conductivity and stability by heat treatment and other methods.

[0065] This application specifically adopts the technical solution of simultaneous transfer from top to bottom, which not only realizes the synchronous transfer of the grid line pattern on the front and back of the cell, but also balances the distribution of force, avoids the problem of hidden cracks in the cell, improves the close fit between the grid line and the cell surface, and improves the current collection efficiency. In the preparation of the conductive paste transfer layer, this application selects PVA as the main material, whose solubility enables the silver paste to be successfully transferred to the cell, and the hot pressing transfer technology ensures the close combination of the silver paste and the cell.

[0066] In addition, the present application also provides a cell grid line preparation device, which can implement the aforementioned cell grid line preparation method in a complete device, thereby improving the integration and automation level of the cell production line. The device includes a transfer substrate, a coating component, a hot pressing component, a slurry coating component, a flattening component, a transfer component, and a transmission mechanism, etc., which can simultaneously process the front and back sides of the cell, greatly shortening the production cycle. Among them, the design of the transfer substrate adopts a circular roller type or a polygonal cross-sectional structure, so that each processing step can be seamlessly connected, effectively saving floor space. In summary, the cell grid line preparation method and device of the present application have significant advantages such as significantly reducing material consumption, improving production efficiency, and ensuring grid line quality and stability, providing a new solution for the preparation of photovoltaic cell grid lines.

[0067] The above is only a specific implementation of the present application, and any other improvements made based on the concept of the present application are deemed to be within the protection scope of the present application.

Claims

1. A method for preparing a grid line of a battery cell, characterized in that: include: Forming conductive paste transfer layers corresponding to the front grid lines and the back grid lines on the transfer substrate respectively, wherein the conductive paste transfer layers include grid line pattern grooves; Filling the gate line pattern groove with a conductive paste; Laminating the conductive paste transfer layer corresponding to the front grid line to the front side of the cell, and laminating the conductive paste transfer layer corresponding to the back grid line to the back side of the cell; Applying pressure on the front and back sides of the cell simultaneously to transfer the conductive paste in the grooves of the grid line pattern to the front and back sides of the cell; The transferred conductive paste is converted into front and back grid lines.

2. The method for preparing a grid line of a battery cell according to claim 1, characterized in that: The process of making the conductive paste transfer layer includes coating a layer of water-soluble polymer material on the transfer substrate, drying the layer and controlling the thickness to be within the range of 10-50 μm.

3. The method for preparing a grid line of a battery cell according to claim 2, characterized in that: The transfer substrate is a soft material.

4. The method for preparing a grid line of a battery cell according to claim 2, characterized in that: A gate line pattern groove is formed on the conductive paste transfer layer by embossing using a mold.

5. The method for preparing a grid line of a battery cell according to claim 4, characterized in that: The gate line pattern includes a first gate line pattern with a groove depth in the range of 10-50 μm and a width in the range of 50-1000 μm and a second gate line pattern with a groove depth in the range of 10-15 μm and a width in the range of 5-50 μm.

6. The method for preparing a grid line of a battery cell according to claim 4, characterized in that: The step of filling the gate line pattern groove with conductive paste includes applying conductive paste on the gate line pattern groove formed by embossing, and scraping off excess conductive paste.

7. The method for preparing a grid line of a battery cell according to claim 1, characterized in that: During the transfer, the temperature is selected within the range of 100-180°C, the applied pressure is within the range of 5-15MPa, and the duration is selected within the range of 2-10min.

8. The method for preparing a grid line of a battery cell according to claim 1, characterized in that: The step of transferring the conductive paste in the grid line pattern groove to the front and back sides of the cell comprises first removing the transfer substrate and then removing the conductive paste transfer layer by liquid dissolution.

9. A battery grid line preparation device, characterized in that: include: Transfer substrate; A coating component, used for coating a conductive paste transfer layer on the transfer substrate; A hot pressing component, used for forming a grid line pattern groove on the conductive paste transfer layer; A slurry coating component, used for filling the gate line pattern groove with a conductive slurry; A scraping component, used for scraping and removing excess conductive slurry; A transfer component, used to attach the conductive paste transfer layer to the surface of the cell, and transfer the conductive paste in the groove of the grid line pattern to the surface of the cell; A transmission mechanism, the transmission mechanism is used to transmit the battery sheet to the station where the transfer component is located; The method comprises the transfer substrate, the coating component, the hot pressing component, the slurry coating component, the scraping component and the transfer component which correspond to the front grid lines and the back grid lines respectively, and simultaneously transfers the conductive slurry to the front and back sides of the battery cell.

10. The battery grid line preparation device according to claim 9, characterized in that: The transfer substrate is a round roller type, and the coating component, the hot pressing component, the slurry coating component, and the scraping component are arranged on the round roller in the order of the coating component, the hot pressing component, the slurry coating component, and the scraping component, and are arranged along the rotation direction of the round roller.

11. The battery grid line preparation device according to claim 9, characterized in that: The cross section of the transfer substrate is polygonal and includes multiple planes, which are arranged on the surface of the transfer substrate in the order of the coating component, the hot pressing component, the slurry coating component and the flattening component, and the order is the same as the rotation direction of the transfer substrate.

12. The battery cell grid line preparation device according to claim 11, characterized in that: It also includes a moving component, which synchronously adjusts the heights of the upper and lower transfer substrates of the battery sheet.

13. The battery grid line preparation device according to claim 9, characterized in that: The invention also comprises a cleaning component which is arranged before the coating station and cleans the surface of the transfer substrate.

14. The battery grid line preparation device according to claim 9, characterized in that: It also includes a drying component, a cleaning component and a sintering component. The drying component is used to dry the conductive paste. The cleaning component is used to dissolve and remove the conductive paste transfer layer using a solution. The sintering component is used to sinter the conductive paste.

15. A battery cell, comprising grid lines on the front and back sides of the battery cell, characterized in that: The grid lines on the front and back are prepared by the method for preparing grid lines of a battery cell according to any one of claims 1 to 8.

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