Sintering optimization method suitable for N-type battery
By using the double peak sintering curve method in the sintering process of N-type batteries, the distribution of sintering temperature is optimized, and the problem of insufficient time in the high temperature zone is solved, and the efficiency and production capacity of the battery are significantly improved.
Patent Information
- Application Number
- CN202311215759.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-20
- Publication Date
- 2025-03-28
AI Technical Summary
In the sintering process of existing N-type batteries, the sintering temperature is shorter in the high temperature zone, resulting in the inability to fully fuse the metal and silicon, forming poor ohmic contact, affecting the battery's filling factor and photoelectric conversion efficiency.
The double peak sintering curve method is used, the sintering temperature of the first peak curve is increased to 730℃, and then the cooling is reduced; the sintering temperature of the second peak curve is increased to 560℃, and then the cooling is reduced. By optimizing the temperature zone setting and heating power control, the battery cell has sufficient time in the high temperature zone.
Through the double peak sintering curve method, the uniformity and durability of the sintering temperature are significantly improved, the ohmic contact quality of the cell is improved, the efficiency and photoelectric conversion efficiency of the solar cell are improved, and the production capacity is increased.
Smart Images
Figure CN119730433A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of photovoltaic cell production, and more particularly to a sintering optimization method suitable for N-type cells. Background Art
[0002] At present, P-type and N-type battery technologies coexist in the photovoltaic industry, showing different characteristics and advantages. Since 2021, N-type batteries have developed rapidly, taking advantage of their high conversion efficiency to enter the stage, starting the transformation of battery technology iteration, and gradually becoming known and accepted by people.
[0003] N-type cells currently generally use a sintering furnace plus an annealing furnace to optimize the high-temperature sintering process and the regeneration recovery process, control the concentration of hydrogen atoms in crystalline silicon and their diffusion movement, and achieve the suppression and improvement of LID in crystalline silicon solar cells.
[0004] Sintering furnace refers to a special equipment that enables powder compacts to obtain the required physical, mechanical properties and microstructure through sintering. The sintering furnace is used to dry the slurry on the silicon wafer, remove the organic components in the slurry, and complete the sintering of the aluminum back field and the grid line. In order to ensure the smooth dewaxing (lubricant or forming agent), reduction, alloying, and organizational transformation of the powder compacts during the sintering process, the sintering temperature, protective atmosphere, compact conveying method, heating and cooling speed, etc. need to be accurately controlled during sintering. Therefore, the sintering furnace should have a complete lubricant burning device (commonly known as a dewaxing belt) in structure, airtightness (that is, it can isolate the air outside the furnace and ensure the smooth flow of the protective atmosphere in the furnace), controllable temperature of each section in the furnace, adjustable sintering atmosphere, and a rapid cooling device to quickly cool the sintered parts to the furnace discharge temperature without oxidation.
[0005] To ensure that the battery cells form a good ohmic contact, the temperature distribution of the entire furnace chamber must meet certain temperature conditions. During the actual sintering process, the battery cells only suddenly heat up in the rear area of the furnace, and the actual temperature in the furnace does not reach the sintering temperature required by the process, resulting in a shorter time for the battery cells in the high temperature zone, which prevents the metal and silicon from fully fusing and forming a good ohmic contact. In addition, the track will block part of the infrared lamp from directly irradiating the battery cells, resulting in poor sintering at the blocked position due to the high temperature time not meeting the process requirements, resulting in unsatisfactory short-circuit current and excessive series resistance, which ultimately affects the fill factor and photoelectric conversion efficiency of the battery, affecting the yield rate and photoelectric conversion efficiency, and the track transmission speed is limited, limiting production capacity. Summary of the invention
[0006] The purpose of the present invention is to address the above-mentioned problems and to provide a sintering optimization method for N-type batteries by designing a double-peak sintering curve, adding a steep slope of peak temperature after the conventional single-peak curve, optimizing the settings of each temperature zone to achieve the best sintering conditions, and further improving the efficiency of solar cells and the photoelectric conversion efficiency.
[0007] The sintering optimization method for N-type batteries provided by the present invention includes two peak sintering curves during the sintering process, specifically:
[0008] For the first peak curve sintering, after the sintering starts, the sintering temperature in the sintering furnace is increased to 730°C at a heating rate of 22°C / S, and during the heating process, the temperature is maintained at 400-499°C for 11-13S, at 500-599°C for 8-10S, at 600-700°C for 7-8S, and at a temperature above 700°C for 2-2.5S, and then the temperature is cooled from 730°C to 15°C at a cooling rate of 40°C / S;
[0009] The second peak curve sintering, within 20 seconds after the first peak curve, the sintering temperature in the sintering furnace is increased to 560°C at a heating rate of 84°C / S, and during the heating process, the temperature is maintained at 400-500°C for 10-12 seconds, and the temperature is maintained at a temperature above 500°C for 7-9 seconds, and then the temperature is cooled from 560°C to room temperature at a cooling rate of 34°C / S;
[0010] After the second peak curve sintering, it enters the annealing chamber process. After two peak sintering, the electrode slurry coated on the battery cell has fully completed the reaction, and the sintering effect has fully reached the technical indicators.
[0011] Furthermore, for the first peak curve sintering and the second peak curve sintering, the sintering temperature in the sintering furnace is adjusted by adjusting the actual power of the infrared heating lamp in the sintering furnace. The battery cell is heated twice in the furnace, and the actual temperature in the furnace can be adjusted as needed to reach the sintering temperature required by the process, so that the time the battery cell spends in the high temperature zone can meet the process requirements, so that the metal and silicon are fully fused and form a good ohmic contact.
[0012] Preferably, the sintering furnace is a sintering and annealing integrated sintering furnace, and the sintering chamber of the sintering furnace includes a total of 7 800W infrared heating lamps in the upper and lower layers of the front section, and 9 1200W infrared heating lamps in the upper and lower layers of the rear section, and the heating power of all infrared heating lamps is controllable; the annealing chamber of the sintering furnace is composed of 6 heating lamps in the upper and lower layers of the front section, and 6 insulation lamps in the upper and lower layers of the rear section, and a total of 18 LED light boards, and all insulation lamps are individually controllable. The finely controllable infrared heating lamps and heating lamps can make the temperature of each area in the furnace more uniform, linear, and controllable.
[0013] Furthermore, a transmission belt with a transmission rate of 15m / min is arranged in the sintering furnace from the entrance through the sintering chamber and annealing chamber to the exit. The battery cells to be sintered coated with electrode slurry are placed on the transmission belt and enter the sintering furnace for sintering and annealing. The automated conveyor line carries the battery cells in the furnace for operation and sintering at the set transmission rate, thereby realizing assembly line production.
[0014] More specifically, the battery cell coated with the electrode slurry to be sintered is placed on a conveyor belt, and enters the sintering furnace with the conveyor belt at a conveying rate of 15m / min. When passing through the front section of the sintering cavity in the sintering furnace, the heating power of the infrared heating lamp arranged in the front section of the sintering cavity is controlled, and the sintering temperature in the sintering furnace is increased from the current temperature to 400-499°C at a heating rate of 22°C / S and maintained for 11-13S, and then continued to increase to 500-599°C and maintained for 8-10S, then increased to 600-700°C and maintained for 7-8S, and finally increased to above 700°C and maintained for 2-2.5S. After the temperature is increased to a maximum of 730°C, the temperature is cooled from 730°C to 15°C at a cooling rate of 40°C / S, and the battery cell moves to the rear section of the sintering cavity with the conveyor belt;
[0015] After the battery cell leaves the front section of the sintering chamber, it enters the back section of the sintering chamber within 20 seconds. By controlling the heating power of the infrared heating lamp arranged in the back section of the sintering chamber, the sintering temperature in the sintering furnace is increased to 400-500°C at a heating rate of 84°C / S and maintained for 10-12S, and then continued to be increased to above 500°C and maintained for 7-9S. After the temperature is increased to a maximum of 560°C, it is cooled from 560°C to room temperature at a cooling rate of 34°C / S. Then, the battery cell moves to the annealing chamber of the sintering furnace along the conveyor belt.
[0016] Beneficial Effects
[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: the present method increases a peak value by optimizing the temperature curve in the sintering furnace chamber. Due to the large adjustable range of the dual temperature zones, the track speed can be further increased, thereby improving production capacity. At the same time, dual temperature zone sintering can further improve the situation where the sintering temperature is too low, resulting in under-firing of the battery cells, unsatisfactory short-circuit current, excessive series resistance, blackening of the EL edge, furnace belt marks, etc., thereby further improving the efficiency of solar cells and the photoelectric conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The foregoing and following detailed description of the present invention will become more apparent when read in conjunction with the following drawings, in which:
[0019] Figure 1 It is a schematic diagram of two peak sintering curves in the sintering process of the present invention. DETAILED DESCRIPTION
[0020] The technical solution for achieving the purpose of the present invention is further described below through specific embodiments. It should be noted that the technical solution claimed to be protected by the present invention includes but is not limited to the following embodiments.
[0021] Example 1
[0022] As a specific implementation scheme of the present invention, the sintering optimization method applicable to N-type batteries provided in this embodiment is as follows: Figure 1 As shown, the sintering process includes two peak sintering curves, specifically:
[0023] For the first peak curve sintering, after the sintering starts, the sintering temperature in the sintering furnace is increased to 730°C at a heating rate of 22°C / S, and during the heating process, the temperature is maintained at 400-499°C for 11-13S, at 500-599°C for 8-10S, at 600-700°C for 7-8S, and at a temperature above 700°C for 2-2.5S, and then the temperature is cooled from 730°C to 15°C at a cooling rate of 40°C / S;
[0024] The second peak curve sintering, within 20 seconds after the first peak curve, the sintering temperature in the sintering furnace is increased to 560°C at a heating rate of 84°C / S, and during the heating process, the temperature is maintained at 400-500°C for 10-12 seconds, and the temperature is maintained at a temperature above 500°C for 7-9 seconds, and then the temperature is cooled from 560°C to room temperature at a cooling rate of 34°C / S;
[0025] After the second peak curve sintering, it enters the annealing chamber process. After two peak sintering, the electrode slurry coated on the battery cell has fully completed the reaction, and the sintering effect has fully reached the technical indicators.
[0026] The method provided in this embodiment increases a peak value by optimizing the temperature curve in the sintering furnace chamber. Due to the large adjustable range of the dual temperature zones, the track speed can be further increased to improve production capacity. At the same time, dual temperature zone sintering can further improve the situation where the sintering temperature is too low, resulting in under-firing of the battery cells, unsatisfactory short-circuit current, excessive series resistance, blackening of the EL edge, furnace belt marks, etc., thereby further improving the efficiency of solar cells and the photoelectric conversion efficiency.
[0027] Example 2
[0028] As a preferred embodiment of the present invention, this example provides a comparison between the sintering preparation of photovoltaic cells using the existing single peak sintering method and the optimized double peak sintering method of the present invention applicable to N-type cells:
[0029] Table 1
[0030]
[0031] First, as shown in Table 1, the rated capacity, open circuit voltage, short circuit current, capacitance, series resistance and series resistance of the resonant circuit of several groups of battery cells prepared by the single peak sintering method in the prior art were tested.
[0032] Secondly, the sintering technology solution including the double peak sintering curve provided by the present application is adopted, specifically:
[0033] The sintering furnace used in this embodiment is a sintering and annealing integrated sintering furnace. The sintering chamber of the sintering furnace includes 7 800W infrared heating lamps in the upper and lower layers of the front section, and 9 1200W infrared heating lamps in the upper and lower layers of the rear section, and the heating power of all infrared heating lamps is controllable; the annealing chamber of the sintering furnace includes 6 heating lamps in the upper and lower layers of the front section, and 6 heat preservation lamps in the upper and lower layers of the rear section, and a total of 18 LED light panels, all heat preservation lamps are individually controllable, and the heat preservation lamps are individually controllable. The refined and controllable infrared heating lamps and temperature-raising lamps can make the temperature of each area in the furnace more uniform, linear and controllable. A transmission belt with a transmission rate of 15m / min is arranged in the sintering furnace from the entrance through the sintering chamber and annealing chamber to the exit. The battery cells to be sintered coated with electrode slurry are placed on the transmission belt and enter the sintering furnace for sintering and annealing. The automated conveyor line carries the battery cells in the furnace for operation and sintering at the set transmission rate, which can realize assembly line production.
[0034] In the first peak curve sintering, the battery cell coated with electrode slurry to be sintered is placed on the conveyor belt and enters the sintering furnace at a transmission rate of 15m / min. After the sintering starts, the sintering temperature in the sintering furnace is increased to 730℃ at a heating rate of 22℃ / S. In the process of heating, when passing through the front section of the sintering cavity in the sintering furnace, the heating power of the infrared heating lamp arranged in the front section of the sintering cavity is controlled to increase the heating power of the infrared heating lamp arranged in the front section of the sintering cavity at a heating rate of 22℃ / S. The sintering temperature in the sintering furnace is increased from the current temperature to 400-499°C and maintained for 11-13S, then continued to increase to 500-599°C and maintained for 8-10S, then increased to 600-700°C and maintained for 7-8S, and finally increased to above 700°C and maintained for 2-2.5S. After the temperature is raised to a maximum of 730°C, the temperature is cooled from 730°C to 15°C at a cooling rate of 40°C / S, and the battery cells are transported to the rear section of the sintering chamber along the conveyor belt.
[0035] The second peak curve sintering, within 20S after passing the first peak curve, by controlling the heating power of the infrared heating lamp arranged in the rear section of the sintering chamber, the sintering temperature in the sintering furnace is increased to 400-500°C at a heating rate of 84°C / S and maintained for 10-12S, and then continued to be increased to above 500°C and maintained for 7-9S. After the temperature is increased to a maximum of 560°C, it is cooled from 560°C to room temperature at a cooling rate of 34°C / S. Then, the battery cell is sent to the annealing chamber of the sintering furnace along the conveyor belt.
[0036] After the second peak curve sintering, it enters the annealing chamber process.
[0037] Table 2
[0038]
[0039] As shown in Table 2, the rated capacity, open circuit voltage, short circuit current, capacitance, series resistance and series resistance of the resonant circuit of several groups of battery cells prepared by the sintering technology scheme including the double peak sintering curve provided in the present application after testing.
[0040] After comparing multiple indicators, it can be seen that the rated capacity of the battery cell prepared by the sintering technology scheme provided in this application including the double peak sintering curve is significantly better than that of the battery cell prepared by the existing method, while the open circuit voltage, short circuit current, capacitance, series resistance and series resistance of the resonant circuit are not significantly inferior to those of the existing method.
Claims
1. A sintering optimization method for N-type batteries, characterized in that: The sintering process includes two peak sintering curves, specifically: For the first peak curve sintering, after the sintering starts, the sintering temperature in the sintering furnace is increased to 730°C at a heating rate of 22°C / S, and during the heating process, the temperature is maintained at 400-499°C for 11-13S, at 500-599°C for 8-10S, at 600-700°C for 7-8S, and at a temperature above 700°C for 2-2.5S, and then the temperature is cooled from 730°C to 15°C at a cooling rate of 40°C / S; The second peak curve sintering, within 20 seconds after the first peak curve, the sintering temperature in the sintering furnace is increased to 560°C at a heating rate of 84°C / S, and during the heating process, the temperature is maintained at 400-500°C for 10-12 seconds, and the temperature is maintained at a temperature above 500°C for 7-9 seconds, and then the temperature is cooled from 560°C to room temperature at a cooling rate of 34°C / S; After the second peak curve sintering, it enters the annealing chamber process.
2. The sintering optimization method for N-type batteries according to claim 1, characterized in that: During the first peak curve sintering and the second peak curve sintering, the sintering temperature in the sintering furnace is adjusted by adjusting the actual power of the infrared heating lamp in the sintering furnace.
3. The sintering optimization method for N-type batteries according to claim 1 or 2, characterized in that: The sintering furnace is an integrated sintering and annealing furnace. The sintering chamber of the sintering furnace includes a total of 7 800W infrared heating lamps on the upper and lower layers of the front section, and 9 1200W infrared heating lamps on the upper and lower layers of the rear section, and the heating power of all infrared heating lamps is controllable; the annealing chamber of the sintering furnace includes 6 heating lamps on the upper and lower layers of the front section, and 6 insulation lamps on the upper and lower layers of the rear section, as well as a total of 18 LED light panels, and all insulation lamps are individually controllable.
4. The sintering optimization method for N-type batteries according to claim 3, characterized in that: A transmission belt with a transmission rate of 15m / min is arranged in the sintering furnace from the entrance through the sintering chamber and annealing chamber to the exit. The battery cells to be sintered coated with electrode slurry are placed on the transmission belt and enter the sintering furnace for sintering and annealing.
5. The sintering optimization method for N-type batteries according to claim 1, characterized in that: The battery sheet to be sintered coated with electrode slurry is placed on the conveyor belt and enters the sintering furnace at a conveying rate of 15m / min. When passing through the front section of the sintering cavity in the sintering furnace, the heating power of the infrared heating lamp arranged in the front section of the sintering cavity is controlled to increase the sintering temperature in the sintering furnace from the current temperature to 400-499°C at a heating rate of 22°C / S and maintain it for 11-13S, then continue to increase it to 500-599°C and maintain it for 8-10S, then increase it to 600-700°C and maintain it for 7-8S, and finally increase it to above 700°C and maintain it for 2-2.5S. After the temperature is increased to a maximum of 730°C, the temperature is cooled from 730°C to 15°C at a cooling rate of 40°C / S, and the battery sheet moves to the rear section of the sintering cavity with the conveyor belt; After the battery cell leaves the front section of the sintering chamber, it enters the back section of the sintering chamber within 20 seconds. By controlling the heating power of the infrared heating lamp arranged in the back section of the sintering chamber, the sintering temperature in the sintering furnace is increased to 400-500°C at a heating rate of 84°C / S and maintained for 10-12S, and then continued to be increased to above 500°C and maintained for 7-9S. After the temperature is increased to a maximum of 560°C, it is cooled from 560°C to room temperature at a cooling rate of 34°C / S. Then, the battery cell moves to the annealing chamber of the sintering furnace along the conveyor belt.