A production equipment and production process based on low temperature sintering technology

Abstract

The present invention discloses a cell, production equipment and production process based on low temperature sintering technology. A cell based on low temperature sintering technology includes a silicon wafer, a pair of opposite end faces of the silicon wafer are respectively deposited with a back film structure and a front film structure, and the front film structure includes a front anti-reflection film, a front aluminum oxide layer and a front fusion layer. A production process for cells based on low temperature sintering technology includes the following steps; S1, texturing and cleaning, S2, boron diffusion, S3, laser doping, S4, etching and cleaning, S5, coating, S6, screen printing, S7, light injection, S8, low temperature sintering. The present application improves the metal semiconductor contact of screen-printed silver paste metallized solar cells, significantly reduces the contact resistance between the grid line and the silicon substrate, and improves the opening voltage and short-circuit current, thereby significantly improving the photoelectric conversion efficiency and fill factor of the cell, and realizing the efficiency upgrade of the cell.

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaic technology, and in particular relates to a production device and a production process based on low-temperature sintering technology. Background Art

[0002] Sintering is the process of drying and decoking the silicon wafer printed with metal paste to volatilize most of the organic solvent in the metal paste, and then sintering it into a battery cell at high temperature, so that the electrode and the silicon wafer itself form an ohmic contact, thereby improving the two key parameters of the battery cell, the open circuit voltage and fill factor, so that the electrode contact has resistance characteristics, so as to achieve the purpose of producing high conversion efficiency batteries.

[0003] However, there are some shortcomings in the production process, as follows:

[0004] The metal semiconductor contact of screen-printed silver paste metallized solar cells needs to be improved.

[0005] The high contact resistance between the gate line and the silicon substrate results in a lower open circuit voltage, which in turn reduces the efficiency of the cell and increases production costs.

[0006] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0007] The purpose of the present invention is to provide a production device and a production process based on low temperature sintering technology, which can solve the problem that the contact resistance between the gate line and the silicon substrate is high, resulting in a decrease in open circuit voltage, thereby causing a decrease in battery cell efficiency and an increase in production costs.

[0008] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:

[0009] A cell based on low temperature sintering technology includes a silicon wafer, and a pair of opposite end faces of the silicon wafer are respectively deposited with a back film structure and a front film structure. The front film structure includes a front anti-reflection film, a front aluminum oxide layer and a front fusion layer, and the front fusion layer, the front aluminum oxide layer and the front anti-reflection film are sequentially deposited on the front side of the silicon wafer from bottom to top. The back film structure includes a tunneling silicon dioxide layer, a back fusion layer, a back aluminum oxide layer and a back anti-reflection film, and the back side of the silicon wafer is sequentially deposited with a tunneling silicon dioxide layer, a back fusion layer, a back aluminum oxide layer and a back anti-reflection film from top to bottom. The production steps of the workshop are simplified, the production efficiency is improved, and the quality of solar cell production is further improved.

[0010] The front fusion layer and the back fusion layer are fused with multiple partitions respectively. The front fusion layer and the back fusion layer are fused with multiple partitions, each including a silver wire layer and a silicon contact. The silicon wafer includes multiple silicon contacts, and the multiple silicon contacts include silicon and metal slurry. The silicon and metal slurry are fused with each other. The silver wire layer is distributed on the contact surface where the silicon and the metal slurry are fused. The silver wire layer is located on the inner end surface of the silicon and is fused with it. The silicon contact is located inside the metal slurry, so as to enhance the mutual fusion quality of the silicon and the metal slurry, further achieve the effect of reducing the contact resistance between the gate line and the silicon substrate, so that the opening voltage and short-circuit current are improved, thereby promoting the upgrade of the efficiency of the battery cell.

[0011] In one or more embodiments of the present invention, the thickness of the silver wire layer is 1-10 μm, and the thickness of the silicon contact is 1-12 μm.

[0012] In one or more embodiments of the present invention, the metal paste is silver, so as to improve the photoelectric conversion efficiency of the solar cell, optimize the charge transfer capacity, and improve the corrosion resistance and oxidation resistance.

[0013] A production device for cells based on low temperature sintering technology, comprising a low temperature sintering device housing, a cell transmission device, a grid line positioning device, a laser emitting device and a detection device. The cell transmission device is located at the inner wall end face of the low temperature sintering device housing, and is used to transmit the cell. The grid line positioning device is located at the inner wall end face of the low temperature sintering device housing, and comprises a visual detection system, a lens and a lifting rod, and the visual detection system is installed on the lower side end face of the lifting rod. The laser emitting device is located at one side end face of the grid line positioning device, and comprises a laser emitter and a sensing control system, and the laser emitter is located at the upper side end face of the cell transmission device, and the laser emitting device is used to emit laser to produce a front fusion layer and a back fusion layer on a pair of opposite end faces of a silicon wafer. The detection device is located at one side end face of the laser emitting device, and comprises a control panel, a probe and a display panel, and the probe is located at the upper side end face of the cell transmission device, so as to start the laser through the low temperature sintering device to process the metal slurry on the front side of the silicon wafer, so that the metal slurry on the front side of the silicon wafer forms a good ohmic contact with the silicon wafer, and detect the surface defects of the cell. If any abnormal situation is found, handle it accordingly.

[0014] In one or more embodiments of the present invention, the production equipment of the battery cell using the low-temperature sintering technology also includes a heat dissipation device, which includes an external compressed air delivery pipe, an external cooling medium pipeline and an external exhaust pipe, so as to achieve effective cooling when the low-temperature sintering equipment generates high temperature during operation, thereby improving the stability of the low-temperature sintering equipment during operation.

[0015] The external compressed air delivery pipe is located at the top end face of the low-temperature sintering equipment shell, the bottom of the external compressed air delivery pipe is connected to a compressed air delivery pipe, the compressed air delivery pipe is distributed on multiple sides of the inner wall of the low-temperature sintering equipment shell, and a plurality of first nozzles are arranged on the compressed air delivery pipe. The external cooling medium pipeline is located at the top end face of the low-temperature sintering equipment shell, the bottom end face of the external cooling medium pipeline is connected to a plurality of cooling delivery pipelines, and the plurality of cooling delivery pipelines are connected to a cooling box, the cooling box includes a heat absorbing medium and a rapid cooling layer, and the rapid cooling layer is connected to the cooling delivery pipeline. The external exhaust duct is located at the top end face of the low-temperature sintering equipment shell, the bottom of the external exhaust duct is connected to an exhaust duct, the exhaust duct is distributed on multiple sides of the inner wall of the low-temperature sintering equipment shell, and a plurality of second nozzles are arranged on the exhaust duct, so that when the heat of the low-temperature sintering equipment is too high during operation, the exhaust device can be started to extract heat and output it to the outside, thereby achieving the purpose of rapid cooling.

[0016] Wherein, a temperature sensor is arranged on one end surface of the inner wall of the shell of the low-temperature sintering equipment.

[0017] A production process for a battery cell based on low temperature sintering technology comprises the following steps; comprising the following steps;

[0018] S1. Texturing and cleaning: This is done in a slot-type single crystal texturing machine to form a clean pyramid velvet surface on the surface of the silicon wafer;

[0019] S2, Boron diffusion: depositing a boron doping layer on the surface of the silicon wafer in a high-temperature diffusion furnace to form a PN junction for separating photogenerated carriers;

[0020] S3, Laser doping: Use SE laser doping equipment to scan the diffusion surface of the silicon wafer with laser, so that the square resistance of some parts of the diffusion surface of the silicon wafer is reduced;

[0021] S4, etching and cleaning;

[0022] S41, BSG etching and alkaline polishing: First, HF is used in the chain etching equipment to etch away the oxide layer on the back of the cell to expose the silicon surface. After removing the oxide layer on the back of the cell, the transfer robot introduces the photovoltaic cells into the wet basket one by one. The wet basket then enters the etching tank at the rear of the alkaline polishing equipment, and passes through the pre-wash tank, alkaline polishing etching tank, alkaline washing tank, and rinsing tank in sequence;

[0023] S42, PSG etching and RCA cleaning: First, use a chain cleaning device to remove the silicon oxide layer on the front surface of the silicon wafer, and then remove the silicon film that is plated around the boron expansion surface during coating, the BSG mask layer on the front side of the silicon wafer, and the oxide layer on the back side. After cleaning, the aluminum oxide passivation layer and silicon nitride protective layer are coated;

[0024] S5, coating;

[0025] S51, silicon dioxide and N-type polysilicon coating: a dense silicon dioxide film with a thickness of about 2nm is deposited on the surface of the silicon wafer, and then SiH 4 , H 2 and PH 3 Reactive deposition of protective intrinsic and doped poly-Si films;

[0026] S52, aluminum oxide coating: depositing an aluminum oxide film on the surface of the silicon wafer;

[0027] S53, Silicon Nitride Coating: Through SiH 4 and NH 3 The reaction forms a dense Si on the surface of the silicon wafer. 3 N 4 membrane;

[0028] S6, screen printing: Use a screen printer to print the metal paste on the back and front sides of the photovoltaic cell in sequence, and dry them separately;

[0029] S7, light injection: Through the sintering furnace light injection integrated machine, the photovoltaic cell is subjected to strong light irradiation treatment at a higher temperature;

[0030] S8, low-temperature sintering: Use a laser emitting device to start laser scanning on the front side of the cell, causing very high charge carrier injection locally; at the same time, apply a negative bias voltage to the contacts of the cell to achieve the production of a front fusion layer and a back fusion layer on a pair of opposite end faces of the silicon wafer.

[0031] In one or more embodiments of the present invention, the specific step of S8 is:

[0032] S81. Use a laser emitting device to start a local laser beam to form induced carriers, which are combined with a bias voltage to form a local current.

[0033] S82. After step S81, a hot spot is generated, and sintering occurs at the corresponding location, causing mutual diffusion of metal slurry and silicon.

[0034] S83, low temperature cooling; the metal paste on the front side of the silicon wafer forms a good ohmic contact with the front side fusion layer.

[0035] In one or more embodiments of the present invention, the path of the local current is a low resistance path, which exists between the emitter and the metal paste under the gate line of the silicon wafer and leads to a high current density.

[0036] In one or more embodiments of the present invention, the duration of the low-temperature sintering process matches the carrier lifetime, and the negative bias voltage is a bias voltage of 9V or more, which can significantly reduce the contact resistance between the metal and the semiconductor.

[0037] Compared with the prior art, the production equipment and production process based on low temperature sintering technology of the present invention have the following benefits:

[0038] , through low-temperature sintering technology, the local laser beam is started to form induced carriers, combined with the bias voltage, to form a local current, which promotes a significant improvement in the fusion quality of silicon and metal paste, and improves the metal semiconductor contact of screen-printed silver paste metallized solar cells.

[0039] The front fusion layer and the back fusion layer are respectively fused with multiple partitions, and the silver wire layer and silicon contacts between the multiple partitions are fused with each other, which can significantly reduce the contact resistance between the gate line and the silicon substrate, improve the opening voltage and short-circuit current, thereby significantly improving the photoelectric conversion efficiency and fill factor of the battery cell, and realizing the efficiency upgrade of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 This is a schematic structural diagram of a front film layer of a battery cell based on low temperature sintering technology in one embodiment of the present invention;

[0042] Figure 2 A schematic diagram of the structure of a battery cell based on low temperature sintering technology in one embodiment of the present invention Figure 1 ;

[0043] Figure 3 It is a schematic diagram of the structure of a production device for a battery cell based on a low temperature sintering technology in one embodiment of the present invention;

[0044] Figure 4 A cross-sectional view of a production device for a battery cell based on low temperature sintering technology in one embodiment of the present invention Figure 1 ;

[0045] Figure 5 A cross-sectional view of a production device for a battery cell based on low temperature sintering technology in one embodiment of the present invention Figure 2 ;

[0046] Figure 6This is a diagram of the production process steps of a battery cell based on low temperature sintering technology in one embodiment of the present invention.

[0047] Description of main reference numerals:

[0048] 1-silicon wafer, 2-front anti-reflection film, 3-front alumina layer, 4-detection device, 5-front fusion layer, 6-emitting electrode, 601-metal slurry, 7-back anti-reflection film, 8-tunneling silicon dioxide layer, 9-back fusion layer, 10-back alumina layer, 11-back electrode, 12-low-temperature sintering equipment shell, 13-cell transmission equipment, 14-external compressed air delivery pipe, 1401-compressed air delivery pipe, 15-external cooling medium pipeline, 1501-cooling delivery pipeline, 1502-cooling box, 15021-heat absorbing medium, 15022-rapid cooling layer, 16-external exhaust duct, 1601-exhaust duct, 17-grid line positioning equipment, 18-laser emitting equipment. DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0050] like Figure 1~Figure 3 As shown, a battery cell based on low temperature sintering technology in one embodiment of the present invention includes a silicon wafer 1, and a pair of opposite end surfaces of the silicon wafer 1 are respectively deposited with a back film layer structure and a front film layer structure.

[0051] The front film structure includes a front anti-reflection film 2, a front aluminum oxide layer 3 and a front fusion layer 5. The front fusion layer 5, the front aluminum oxide layer 3 and the front anti-reflection film 2 are sequentially deposited on the front of the silicon wafer 1 from bottom to top.

[0052] The back film layer structure includes a tunneling silicon dioxide layer 8, a back fusion layer 9, a back aluminum oxide layer 10 and a back anti-reflection film 7. The back side of the silicon wafer 1 is deposited with the tunneling silicon dioxide layer 8, the back fusion layer 9, the back aluminum oxide layer 10 and the back anti-reflection film 7 in sequence from top to bottom.

[0053] The front fusion layer 5 and the back fusion layer 9 are each fused with a plurality of partitions.

[0054] The bottom end surface of the emitting electrode 6 is provided with a metal paste 601, and the emitting electrode 6 can sequentially pass through the front anti-reflection film 2 and the front aluminum oxide layer 3 to contact the front fusion layer 5. The back electrode 11 can sequentially pass through the back anti-reflection film 7 and the back aluminum oxide layer 10 to contact the back fusion layer 9.

[0055] Further, such as Figure 4 As shown, the front fusion layer 5 and the back fusion layer 9 are fused with multiple partitions, each including a silver wire layer and a silicon contact. The silicon wafer 1 includes multiple silicon contacts, and the multiple silicon contacts include silicon and metal paste. The silicon and the metal paste are fused with each other. The silver wire layer is distributed on the contact surface where the silicon and the metal paste are fused. The silver wire layer is located on the inner end face of the silicon and is fused with it. The silicon contact is located inside the metal paste, thereby strengthening the mutual fusion of silicon and the metal paste, further achieving the reduction of the contact resistance between the gate line and the silicon substrate, the increase of the opening voltage and the short-circuit current, and promoting the upgrade of the battery cell efficiency.

[0056] It should be noted that when the metal slurry content in the silicon contact is less than 20%, and through the processing of low-temperature sintering technology, it can induce the mutual diffusion of silicon and silver to form local submicron point contacts. That is, when the metal slurry is less than 20%, the sintering activity is higher than that of the metal slurry with a higher content, and the porosity of the electrode is significantly reduced, which can promote the mutual diffusion of silicon and silver. Thereby significantly reducing the contact resistance between the gate line and the silicon substrate, increasing the opening voltage and short-circuit current, and thus significantly improving the photovoltaic conversion efficiency and fill factor of the cell, and realizing the efficiency upgrade of the cell.

[0057] Among them, the thickness of the silver wire layer is 1~10μm, and the thickness of the silicon contact is 1~12μm.

[0058] Preferably, the metal paste is silver, which has good electrical and thermal conductivity, can also improve photoelectric conversion efficiency, optimize charge transfer capacity, and improve corrosion resistance and oxidation resistance. It is currently the most suitable metal paste to use.

[0059] like Figure 6 As shown, a production process of a battery cell based on low temperature sintering technology includes the following steps;

[0060] S1. Velvet cleaning:

[0061] The silicon wafers are placed in a silicon wafer box, and the automatic silicon wafer flipping machine guides the silicon wafers into the wet flower basket in an orderly manner. The wet flower basket is automatically transmitted into the trough-type single crystal texturing machine, and passes through pre-cleaning, texturing, post-cleaning, pickling, slow pulling, drying tank, etc. in sequence, and finally a clean pyramid velvet surface is formed.

[0062] S2. Boron diffusion:

[0063] A boron-doped layer is deposited on the surface of the silicon wafer in a high-temperature diffusion furnace to form a PN junction for separating photogenerated carriers.

[0064] It should be noted that the diffusion source is BCl3.

[0065] S3, Laser doping:

[0066] Using SE laser doping equipment, the laser is scanned on the diffusion surface of the silicon wafer, so that the square resistance of some parts of the diffusion surface of the silicon wafer is reduced.

[0067] S4, etching and cleaning:

[0068] S41, BSG etching and alkali polishing:

[0069] First, HF is used in the chain etching equipment to etch away the oxide layer on the back of the cell to expose the silicon surface. During the etching process, the boron diffusion surface of the cell is protected by a water film to protect the oxide layer on the front of the cell, which is used as a mask layer for alkaline polishing on the back.

[0070] After removing the oxide layer on the back of the cell, the transfer robot guides the photovoltaic cells into the wet basket one by one. The wet basket then enters the etching tank at the rear end of the alkaline polishing equipment, and passes through the pre-washing tank, alkaline polishing etching tank, alkaline washing tank, and rinsing tank in sequence.

[0071] S42, PSG etching and RCA cleaning:

[0072] First, the silicon oxide layer on the front surface of the silicon wafer is removed by chain cleaning equipment, and then the silicon wafer is introduced into the wet process basket by an automatic wafer reversing machine. The basket is placed in an alkali tank to etch away the silicon film that is plated around the boron expansion surface during coating, and then the BSG mask layer on the front side of the silicon wafer and the oxide layer on the back side are cleaned with acid etching liquid. After the cleaned silicon wafers are collected, they are sent to the coating process to complete the coating of the aluminum oxide passivation layer and the silicon nitride protective layer.

[0073] S5, coating:

[0074] S51, silicon dioxide and N-type polysilicon coating:

[0075] Through silane and N 2 O reacts to form a dense silicon dioxide film with a thickness of about 2nm on the surface of the silicon wafer. 4 , H 2 and PH 3The reaction deposits the intrinsic and doped poly-Si films that play a protective role. The entire coating process is carried out in the PECVD equipment. The automatic wafer rewinder inserts the silicon wafer into the graphite boat, starts the program, and the equipment runs automatically. The gases required for the reaction process are supplied by the special gas station. After the initial combustion treatment, the waste gas is discharged into the silane combustion tower and the waste gas absorption tower for full treatment and absorption, and then discharged through the exhaust pipe, and the waste liquid is discharged into the sewage treatment station for treatment.

[0076] S52, Aluminum Oxide Coating:

[0077] By trimethylaluminum and H 2 O reacts to form a uniform aluminum oxide film on the surface of the silicon wafer. The entire coating process is carried out in the ALD equipment. The automatic wafer flipper inserts the silicon wafer into the aluminum boat, starts the program, and the equipment runs automatically. The tail gas of trimethylaluminum is first treated with the tail gas treatment equipment and then discharged into the waste gas tower for treatment.

[0078] S53, Silicon Nitride Coating:

[0079] By SiH 4 and NH 3 The reaction forms a dense Si on the surface of the silicon wafer. 3 N 4 The process is carried out in the PECVD equipment. The automatic wafer reversing machine loads the silicon wafer to be coated into the graphite boat, starts the program, and the equipment runs automatically. The SiH required for the reaction 4 and NH 3 They are all supplied by the special gas station, and the waste gas generated by the reaction is discharged into the silane combustion tower for treatment, and then discharged through the exhaust pipe after meeting the treatment standards.

[0080] S6, Screen printing:

[0081] The metal pastes on the back and front sides are printed on the photovoltaic cells in sequence by a screen printer and dried separately;

[0082] S7, light injection:

[0083] Through the sintering furnace light injection integrated machine, the photovoltaic cells are irradiated with strong light at a higher temperature, which greatly improves the stability of the photovoltaic cells and reduces the light-induced degradation and electrical degradation.

[0084] S8, low temperature sintering:

[0085] The laser emitting device 18 is used to start the laser scanning on the front of the cell, which locally causes very high charge carrier injection. At the same time, a negative bias voltage is applied to the contacts of the cell. High injection and negative bias lead to high current density through the contact interface, improving the metal semiconductor contact of the screen-printed silver paste metallized solar cell. In this process, the contact resistance between the gate line and the silicon substrate can be significantly reduced, the opening voltage and short-circuit current can be increased, thereby significantly improving the photovoltaic conversion efficiency and fill factor of the cell, and realizing the efficiency upgrade of the cell. That is, in this step, a silver wire layer and silicon contacts are generated on the surface of the silicon wafer 1.

[0086] S81, using the laser emitting device 18 to start the local laser beam to form induced carriers, combined with the bias voltage, to form a local current; the preferred path of the local current is a low resistance path, which exists between the emitter and the metal paste under the gate line of the silicon wafer 1. That is, the path must already exist between the emitter and the silver under the gate line and lead to a high current density. These paths can be found at or near the top of the pyramid.

[0087] The negative bias voltage is a bias voltage of 9 V or more. The preferred bias voltage is 12 V, and the local current of several amperes generated thereby can significantly reduce the contact resistance between the metal and the semiconductor.

[0088] S82. After step S81, a hot spot is generated, and sintering occurs at the corresponding location, causing mutual diffusion of metal slurry and silicon.

[0089] S83, low temperature cooling: the metallic silver on the front side of the silicon wafer 1 forms a good ohmic contact with the front side fusion layer 5.

[0090] The metal paste on the front of the silicon wafer is processed by starting the laser through the low-temperature sintering equipment, so that the metal paste on the front of the silicon wafer forms a good ohmic contact with the silicon wafer. At the same time, the charging effect is used to optimize the gate electrode, improve the contact resistance and achieve the output of high-efficiency solar photovoltaic cells, thereby significantly improving the photoelectric efficiency of the cells.

[0091] In general, the low-temperature sintering process utilizes the highly energy-concentrated and controllable characteristics of the laser to separate the two key steps of passivation layer erosion and contact formation during high-temperature sintering, thereby achieving further precise control of the sintering process.

[0092] The current generated by the laser is transmitted along the low contact resistance path, inducing silver-silicon interdiffusion, thereby reducing the contact resistance; the laser stops quickly after passing, thereby achieving maximum retention of the original passivation layer and avoiding carrier recombination caused by direct contact with the metal silicon substrate.

[0093] It is important to note that the duration of the low-temperature sintering process matches the carrier lifetime.

[0094] like Figure 3~Figure 5 As shown, a production device for cells based on low temperature sintering technology includes a low temperature sintering device housing 12, a cell transmission device 13, a grid line positioning device 17, a laser emitting device 18 and a detection device 4. The low temperature sintering process in the silicon wafer processing process is realized.

[0095] The cell conveying device 13 is located at the inner wall end face of the low-temperature sintering equipment shell 12. The cell conveying device 13 includes a transfer belt and a drive motor. A pair of relative end faces of the cell conveying device 13 both protrude from the outer end face of the low-temperature sintering equipment shell 12. When the cell is subjected to low-temperature sintering, the cell is placed in the cell conveying device 13 for conveying and processing.

[0096] The grid line positioning device 17 is located on the inner wall end face of the low temperature sintering equipment housing 12. The grid line positioning device 17 includes a visual inspection system, a lens and a lifting rod. The visual inspection system is installed on the lower side end face of the lifting rod. After taking a picture through the lens and uploading it to the visual inspection system, the positioning method of the edge and the main grid line is used, and calculation is performed to finally obtain the corresponding position of the battery cell, which is convenient for the normal operation of the next process laser emission device 18. Reduce errors.

[0097] The laser emitting device 18 is located on one side end surface of the grid line positioning device 17, and includes a laser emitter and a sensing control system. The laser emitter is located on the upper side end surface of the battery cell transmission device 13, and the laser emitting device 18 is used to emit laser.

[0098] Specifically, a specific high-density laser spot is used to process the surface of the cell. Through specific treatment of the gate, the passivation performance and contact performance of the cell are optimized, and the open circuit voltage and fill factor of the cell are improved. After multiple experimental verifications, it is concluded that the laser optimized contact process can increase the photoelectric conversion efficiency of the cell by 0.2% or more.

[0099] The detection device 4 is located on one side of the laser emitting device 18. The detection device 4 includes a control panel, a probe and a display panel. The probe is located on the upper side of the cell transmission device 13. The probe is used to contact and detect electronic components, convert the detection results into electrical signals, and perform preliminary detection on the cells that have completed low-temperature sintering, detect the open circuit voltage, short circuit current, efficiency and other indicators of the cells, and detect surface defects and flaws of the cells, such as cracks, quality problems, non-uniform imprinting, and damage on welding. If abnormal conditions are found, corresponding treatment shall be carried out in a timely manner.

[0100] The production equipment of the battery cell using the low temperature sintering technology includes a heat dissipation device, which includes an external compressed air delivery pipe 14, an external cooling medium pipeline 15 and an external exhaust pipe 16.

[0101] The external compressed air delivery pipe 14 is located at the top end surface of the low-temperature sintering equipment housing 12, and the bottom of the external compressed air delivery pipe 14 is connected to a compressed air delivery pipe 1401, so that the compressed air is connected to the external compressed air delivery pipe 14 and delivered to the compressed air delivery pipe 1401;

[0102] The compressed air delivery pipe 1401 is distributed on multiple side surfaces of the inner wall of the low-temperature sintering equipment shell 12. Multiple first nozzles are arranged on the compressed air delivery pipe 1401, so that the compressed air is sprayed into multiple end surfaces in the low-temperature sintering equipment shell 12 through the first nozzles for cooling, thereby realizing cooling of the low-temperature sintering equipment during the high temperature period generated during operation.

[0103] The external exhaust duct 16 is located at the top end surface of the low-temperature sintering equipment shell 12. The bottom of the external exhaust duct 16 is connected to an exhaust duct 1601. The exhaust duct 1601 is distributed on multiple side surfaces of the inner wall of the low-temperature sintering equipment shell 12. Multiple second nozzles are arranged on the exhaust duct 1601.

[0104] Specifically, an external exhaust device is connected through the external exhaust duct 16, negative pressure is delivered through the exhaust duct 1601, and heat is absorbed through multiple second nozzles, thereby achieving the purpose of enhanced cooling. When the low-temperature sintering equipment has too high heat during operation, the exhaust device can be started to extract heat and output it to the outside, thereby achieving the purpose of rapid cooling.

[0105] It should be noted that the external compressed air delivery pipe 14 and the external exhaust duct 16 do not operate at the same time.

[0106] like Figure 5 As shown, the external cooling medium pipeline 15 is located at the top end surface of the low-temperature sintering equipment shell 12, and the bottom end surface of the external cooling medium pipeline 15 is connected to multiple cooling delivery pipelines 1501, and the multiple cooling delivery pipelines 1501 are all connected to a cooling box 1502, and the cooling box 1502 includes a heat absorbing medium 15021 and a rapid cooling layer 15022;

[0107] Multiple cooling boxes 1502 are fixedly connected to multiple end faces of the silicon wafer 1, and the heat absorbing medium 15021 stores a heat absorbing medium to absorb heat. The heat absorbing medium is preferably a composite phase change material of paraffin and graphite. Paraffin, as a phase change material, is responsible for absorbing and storing heat to achieve the temperature control function. Graphite has a microscopic porous structure. When the paraffin phase changes into a liquid state, the graphite plays a perfect adsorption role to prevent the material from being in a liquid state. This can further achieve enhanced cooling of the equipment.

[0108] The rapid cooling layer 15022 is connected to the cooling conveying pipeline 1501. When the low-temperature sintering equipment is in operation and the temperature reaches the warning value, the high temperature cannot be quickly reduced by the external exhaust duct 16 alone. In this way, the external cooling medium pipeline 15 is started. The external cooling medium pipeline 15 is externally connected to liquid nitrogen. The liquid nitrogen enters the rapid cooling layer 15022 through the cooling conveying pipeline 1501, so as to quickly cool down the surrounding high temperature, and the cooling effect is fast.

[0109] A temperature sensor is provided on one end face of the inner wall of the low temperature sintering equipment housing 12 to monitor the temperature. When the temperature is between 30 and 50 degrees, the external exhaust duct 16 is started to cool down. When the temperature reaches above 50 degrees, the external cooling medium duct 15 is started to cool down.

[0110] During use, when a low-temperature sintering process is required, the battery cell is transported to the battery cell transport device 13 for transmission, the battery cell passes through the lower end face of the grid line positioning device 17 for grid line positioning, and the positioning information is transmitted to the main drive system, the main drive system controls the laser emitting device 18 to drive the laser emitter according to the positioning, and processes the surface of the battery cell. Through the specific treatment of the gate, the passivation performance and contact performance of the battery cell are optimized, and the open circuit voltage and fill factor of the battery cell are improved.

[0111] After processing is completed, the cell conveying device 13 conveys the cell to the lower end face of the detection device 4 for preliminary detection. If the open circuit voltage, short circuit current, efficiency, surface defects and flaws of the cell are found, an early warning is issued in time.

[0112] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0113] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A battery cell production equipment based on low temperature sintering technology, characterized in that: Included are: Low temperature sintering equipment housing; The cell transfer device is located on the inner wall end surface of the low-temperature sintering equipment housing and is used to transfer the cell; The grid line positioning device is located on the inner wall end surface of the low-temperature sintering device housing, and includes a visual detection system, a lens and a lifting rod, wherein the visual detection system is installed on the lower side end surface of the lifting rod; A laser emitting device, located on one side of the gate line positioning device, includes a laser emitter and a sensing control system. The laser emitter is located on the upper side of the cell transmission device. The laser emitting device is used to emit laser to produce a front fusion layer and a back fusion layer on a pair of opposite end surfaces of the silicon wafer. A detection device, located on one side of the laser emitting device, includes a control panel, a probe and a display panel, and the probe is located on the upper side of the battery cell transmission device; A heat dissipation device, the heat dissipation device comprising: An external compressed air delivery pipe is located on the top end surface of the low-temperature sintering equipment housing, the bottom of the external compressed air delivery pipe is connected with a compressed air delivery pipe, the compressed air delivery pipe is distributed on multiple side surfaces of the inner wall of the low-temperature sintering equipment housing, and multiple first nozzles are arranged on the compressed air delivery pipe; An external cooling medium pipeline is located on the top end face of the low-temperature sintering equipment shell, and a plurality of cooling delivery pipelines are connected to the bottom end face of the external cooling medium pipeline, and the plurality of cooling delivery pipelines are all connected to a cooling box, and the plurality of cooling boxes are all fixedly connected to a plurality of end faces of the silicon wafer, and the cooling box includes a heat absorbing medium and a rapid cooling layer, and the heat absorbing medium is a composite phase change material of paraffin and graphite, and the rapid cooling layer is connected to the cooling delivery pipeline, and the external cooling medium pipeline is externally connected to liquid nitrogen, and the liquid nitrogen enters the rapid cooling layer through the cooling delivery pipeline; An external exhaust duct is located on the top end surface of the low-temperature sintering equipment shell, the bottom of the external exhaust duct is connected to an exhaust duct, the exhaust duct is distributed on multiple side surfaces of the inner wall of the low-temperature sintering equipment shell, and multiple second nozzles are arranged on the exhaust duct; Wherein, a temperature sensor is arranged on one end surface of the inner wall of the shell of the low-temperature sintering equipment.

2. A production process of a battery cell based on low temperature sintering technology, using the production equipment of a battery cell based on low temperature sintering technology according to claim 1, characterized in that: The following steps are included: S1. Texturing and cleaning: This is done in a slot-type single crystal texturing machine to form a clean pyramid velvet surface on the surface of the silicon wafer; S2, Boron diffusion: depositing a boron doping layer on the surface of the silicon wafer in a high-temperature diffusion furnace to form a PN junction for separating photogenerated carriers; S3, Laser doping: Use SE laser doping equipment to scan the diffusion surface of the silicon wafer with laser, so that the square resistance of some parts of the diffusion surface of the silicon wafer is reduced; S4, etching and cleaning: S41, BSG etching and alkaline polishing: First, HF is used in the chain etching equipment to etch away the oxide layer on the back of the cell to expose the silicon surface. After removing the oxide layer on the back of the cell, the transfer robot introduces the photovoltaic cells into the wet basket one by one. The wet basket then enters the etching tank at the rear of the alkaline polishing equipment, and passes through the pre-wash tank, alkaline polishing etching tank, alkaline washing tank, and rinsing tank in sequence; S42, PSG etching and RCA cleaning: First, use a chain cleaning device to remove the silicon oxide layer on the front surface of the silicon wafer, and then remove the silicon film that is plated around the boron expansion surface during coating, the BSG mask layer on the front side of the silicon wafer, and the oxide layer on the back side. After cleaning, the aluminum oxide passivation layer and silicon nitride protective layer are coated; S5, coating: S51, silicon dioxide and N-type polysilicon coating: a 2nm thick dense silicon dioxide film is deposited on the surface of the silicon wafer, and then a doped poly-Si film is deposited by reacting SiH4, H2 and PH3; S52, aluminum oxide coating: depositing an aluminum oxide film on the surface of the silicon wafer; S53, Silicon nitride coating: Through the reaction of SiH4 and NH3, a dense Si3N4 film is deposited on the surface of the silicon wafer; S6, screen printing: Use a screen printer to print the metal paste on the back and front sides of the photovoltaic cell in sequence, and dry them separately; S7, light injection: Through the sintering furnace light injection integrated machine, the photovoltaic cell is subjected to strong light irradiation treatment at a higher temperature; S8, low temperature sintering: using a laser emitting device to start laser scanning on the front side of the cell, locally causing very high charge carrier injection; at the same time, applying a negative bias voltage to the contacts of the cell to achieve the production of a front fusion layer and a back fusion layer on a pair of opposite end faces of the silicon wafer; The specific steps of S8 are: S81, using a laser emitting device to start a local laser beam to form induced carriers, and combining with a negative bias voltage to form a local current; S82, after step S81, a hot spot is generated, and sintering occurs at the corresponding location, causing mutual diffusion of metal slurry and silicon; S83, low temperature cooling; the metal paste on the front side of the silicon wafer forms a good ohmic contact with the front side fusion layer.

3. The production process of a battery cell based on low temperature sintering technology according to claim 2, characterized in that: The duration of the low temperature sintering process matches the carrier lifetime, and the negative bias voltage is a bias voltage above 9V.

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