An IBC battery aluminum paste, an IBC battery and a preparation method thereof

Abstract

The embodiment of the present application provides an IBC battery aluminum paste, an IBC battery and a preparation method thereof, wherein the IBC battery aluminum paste provided by the embodiment of the present application comprises an organic additive, boron powder, aluminum powder, indium powder, an organic binder and doped glass powder, and the doping substance of the doped glass powder is one or more of lead and bismuth. By adding the indium powder in the aluminum paste and using the glass powder doped with lead and / or bismuth, the passivation layer region above the p+ doped region is directly printed, then high-temperature sintering is carried out, the positive electrode grid line can be contacted with the p+ doped region and formed, the step of secondary laser slotting is omitted, the passivation layer is prevented from being damaged by the secondary laser slotting, and the open-circuit voltage of the battery can be improved.

Description

Technical Field

[0001] This invention relates to the field of crystalline silicon solar cell manufacturing technology, and in particular to an IBC cell aluminum paste, an IBC cell, and a method for preparing the same. Background Technology

[0002] Interdigitated Back Contact (IBC) batteries are a new type of battery in which the P / N junction, substrate and emitter contact electrodes are made in an interdigitated shape on the back of the battery. The core technology is to prepare high-quality p-regions and n-regions that are interdigitated and spaced apart in an interdigitated shape on the back of the battery.

[0003] Currently, P-type IBC batteries require laser grooving of the P+ region before printing grid lines to facilitate the printing of aluminum paste to form positive electrode grid lines. However, laser grooving not only increases the manufacturing process but also damages the passivation layer, resulting in a decrease in the open-circuit voltage of the battery. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an IBC battery aluminum paste, an IBC battery and a method for preparing the same, so as to solve the problem that the open circuit voltage of the battery cell is reduced because the P+ region needs to be laser-grooved before the aluminum paste of the existing IBC battery is printed into positive grid lines.

[0005] To solve the above problems, the present invention is achieved through the following technical solution:

[0006] This invention proposes an aluminum paste for IBC batteries, wherein the components constituting the aluminum paste include organic additives, boron powder, aluminum powder, indium powder, organic binder, and doped glass powder, wherein the dopant of the doped glass powder is one or more of lead and bismuth.

[0007] Furthermore, in the IBC battery aluminum paste, the mass fractions of the organic additive, boron powder, aluminum powder, indium powder, organic binder, and doped glass powder are 0.3-0.5%, 0.05-0.1%, 70-76%, 0.5-1%, 20.6-27.95%, and 1.2-1.8%, respectively.

[0008] Furthermore, in the IBC battery aluminum paste, the doped glass powder, by mass, is obtained by sintering and pulverizing 15-25 parts Bi2O3, 6-8 parts Al2O3, 10-25 parts Pb2O5, 5-15 parts ZnO, 10-15 parts Sb2O5, 5-15 parts V2O5, 12-20 parts TiO2, and 12-20 parts BaO.

[0009] Furthermore, in the IBC battery aluminum paste, the indium powder is micron-sized elemental indium.

[0010] Furthermore, in the IBC battery aluminum paste, the organic additives include one or more of the following: fatty alcohol ether phosphate, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, lauryl phosphate, silicone oil, diester, and a mixture of lauryl phosphate.

[0011] Furthermore, in the IBC battery aluminum paste, the organic binder includes a polymer resin and an organic solvent;

[0012] The polymer in the organic adhesive has a mass fraction of 9-14%;

[0013] The organic solvent has a mass fraction of 86-91% in the organic adhesive.

[0014] Furthermore, in the IBC battery aluminum paste, the polymer is ethyl cellulose-N2O;

[0015] The organic solvent includes at least four of the following: benzyl alcohol, diethyl phthalate, terpineol, butylcarbiol, butylcarbiol acetate, tributyl citrate, Span 85, and ester twelve.

[0016] Furthermore, in the IBC battery aluminum paste, the aluminum powder comprises 85-90% by mass of micron-sized spherical aluminum powder and 10-15% by mass of nano-sized spherical aluminum powder.

[0017] This invention also proposes a method for preparing an IBC battery, comprising:

[0018] After forming interdigitated n+ doped regions and p+ doped regions on the back side of the silicon wafer, a passivation layer is formed on the surface of the n+ doped regions and p+ doped regions.

[0019] Aluminum paste is printed in a first region of the passivation layer, and silver paste is printed in a second region of the passivation layer; the projection of the first region is within the p+ doped region, and the projection of the second region is within the n+ doped region; wherein, the components constituting the aluminum paste include organic additives, boron powder, aluminum powder, indium powder, organic binder, and doped glass powder, and the dopant of the doped glass powder is one or more of lead and bismuth;

[0020] IBC cells are prepared by high-temperature sintering of a P-type silicon wafer with aluminum paste printed in the first region and silver paste printed in the second region.

[0021] The present invention also proposes an IBC battery, wherein the IBC battery is prepared by the method described in claim 9.

[0022] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0023] In this embodiment of the invention, the provided IBC battery aluminum paste comprises organic additives, boron powder, aluminum powder, indium powder, organic binder, and doped glass powder. The dopant in the doped glass powder is one or more of lead and bismuth. By adding indium powder to the aluminum paste and using lead and / or bismuth-doped glass powder, indium, like aluminum, belongs to Group 3 and has similar chemical properties. Indium, lead, and bismuth have etching properties and high density. After forming a passivation layer on the back of the battery silicon wafer, the passivation layer is directly printed onto the passivation layer region above the p+ doped region, followed by high-temperature sintering. This allows for contact with the p+ doped region and the formation of the positive electrode grid line, eliminating the need for a secondary laser grooving step and avoiding damage to the passivation layer caused by secondary laser grooving. This improves the battery open-circuit voltage. Simultaneously, during the sintering process... The rapid descent of aluminum to the silicon surface increases the probability of In-Si contact, reducing the contact resistance between the paste and the cell, and maintaining a higher open-circuit voltage. In addition, the use of indium to replace part of the aluminum powder reduces the aluminum content, which helps to reduce the side effects of Al, weakens the Al-Si reaction, and results in shallower silver-aluminum corrosion pits and reduced recombination, thereby improving the open-circuit voltage and efficiency of the cell. Thus, it solves the problem that existing IBC cell aluminum pastes require laser grooving of the P+ region before printing into positive electrode grid lines, which leads to a decrease in the open-circuit voltage of the cell.

[0024] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0025] Figure 1 This is a flowchart of the method for preparing aluminum paste for IBC batteries provided in an embodiment of the present invention;

[0026] Figure 2 This is a flowchart of the preparation method of the IBC battery provided in the embodiment of the present invention. Detailed Implementation

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] The applicant of this invention has discovered that the metallization printing paste for P-type IBCs is currently mainly composed of aluminum paste. Aluminum paste can cause significant metal bonding to the cell itself, increasing the series resistance of the cell, reducing the electrical performance of the cell, resulting in low on-state voltage, high series resistance, poor filling, and easily affecting the efficiency of the cell itself.

[0029] To address the aforementioned problems, this invention provides an IBC battery aluminum paste. The components of the aluminum paste include organic additives, boron powder, aluminum powder, indium powder, organic binder, and doped glass powder. The dopant in the doped glass powder is one or more of lead and bismuth.

[0030] The aluminum paste for IBC batteries provided in this embodiment of the invention is specifically an aluminum paste for forming the positive grid lines of a P-type IBC battery.

[0031] Aluminum powder is the main component, mainly used to replace the P+ emitter of the battery. Indium has low resistance, good ductility, thermal conductivity, electrical conductivity and burn-through properties. Indium and aluminum are both Group 3 elements and have similar chemical properties. When the aluminum paste is printed on the passivation layer on the back of the silicon wafer, the silicon nitride film and silicon oxide film in the passivation layer can be burned through in sequence, and then contact the p+ doped region to form the positive electrode grid line. This eliminates the need for the secondary laser grooving step and avoids damage to the passivation layer caused by the secondary laser grooving.

[0032] Among them, boron powder can diffuse into the silicon interior for heavy doping during high-temperature sintering, which is beneficial to improving the contact performance of the slurry and reducing the reaction contact surface between aluminum and silicon.

[0033] Among them, the doped glass powder is an inorganic binder that melts into a liquid state under high temperature conditions and solidifies upon cooling, thus playing a bonding role. The doping elements lead and bismuth have etching properties and high density, which can not only form a good aluminum-silicon alloy layer and P+ layer doping with silicon, but also penetrate into the spaces between aluminum grains to improve the material structure, increase the conductivity of the battery, and thus improve the battery efficiency. This solves the problem that the aluminum paste on the front grid of existing N-type TOPCon batteries is prone to affecting battery efficiency due to the presence of aluminum. The organic binder can ensure the overall bonding effect, and the organic additives can reduce the overall viscosity of the silver paste.

[0034] Therefore, the aluminum paste provided in this embodiment of the invention has better contact with the battery cell itself, lower series resistance than traditional aluminum paste, and significantly improved recombination rate and degree. The open-circuit voltage of the battery can be increased by 5 millivolts, thus solving the problem that existing P-type IBC batteries require laser grooving of the P+ region when printing the positive grid lines, which leads to a decrease in the open-circuit voltage of the battery cell.

[0035] Optionally, in one embodiment, the aluminum paste contains the following components by mass percentage: organic additives (0.3-0.5%), boron powder (0.05-0.1%), aluminum powder (70-76%), indium powder (0.5-1%), organic binder (20.6-27.95%), and doped glass powder (1.2-1.8%). The aluminum paste provided in this embodiment has a low aluminum content. During the formation of the aluminum-silicon alloy, the proportion of aluminum in the alloy is relatively small. Therefore, during the cooling process, no excess aluminum diffuses into the PN junction region, preventing the formation of a metal composite region.

[0036] Optionally, in one embodiment, the mass fractions of organic additives, boron powder, aluminum powder, indium powder, organic binder, and doped glass powder in the aluminum paste are 0.35-0.45%, 0.06-0.08%, 72-75%, 0.6-0.8%, 23-26%, and 1.35-1.45%, respectively.

[0037] For example, in the aluminum paste, the mass fractions of organic additives, boron powder, aluminum powder, indium powder, organic binder, and doped glass powder are 0.3%, 0.1%, 70%, 0.5%, 27.95%, and 1.15%, respectively.

[0038] For example, in the aluminum paste, the mass fractions of organic additives, boron powder, aluminum powder, indium powder, organic binder, and doped glass powder are 0.5%, 0.05%, 76%, 1%, 21.25%, and 1.2%, respectively.

[0039] For example, in the aluminum paste, the mass fractions of organic additives, boron powder, aluminum powder, indium powder, organic binder, and doped glass powder are 0.5%, 0.1%, 76%, 1%, 20.6%, and 1.8%, respectively.

[0040] For example, in the aluminum paste, the mass fractions of organic additives, boron powder, aluminum powder, indium powder, organic binder, and doped glass powder are 0.4%, 0.06%, 72%, 0.5%, 25.54%, and 1.5%, respectively.

[0041] For example, in the aluminum paste, the mass fractions of organic additives, boron powder, aluminum powder, indium powder, organic binder, and doped glass powder are 0.4%, 0.1%, 75%, 1%, 22%, and 1.5%, respectively.

[0042] Optionally, in one embodiment, the indium powder is micron-sized elemental indium, specifically micron-sized elemental indium with a purity of 2 nines.

[0043] Optionally, in one embodiment, the boron powder comprises micron-sized elemental boron. By adding this micron-sized elemental boron, the boron powder can rapidly diffuse into the silicon interior for heavy doping during high-temperature sintering, which is beneficial for improving the contact performance of the slurry.

[0044] Optionally, in one specific embodiment, the boron powder is micron-sized boron powder with a purity of 99.99%.

[0045] Alternatively, in another embodiment, the boron powder comprises a boron-aluminum alloy. By adding this micron-sized boron-aluminum alloy powder, the aluminum paste can quickly form a good alloy with silicon at a lower sintering temperature, reducing the contact resistivity between the front-side aluminum grid and the battery.

[0046] Optionally, in one embodiment, the aluminum powder includes micron-sized spherical aluminum powder and nano-sized spherical aluminum powder. This is because there are gaps between the micron-sized aluminum powder particles, and the aforementioned nano-sized spherical aluminum powder can fill and penetrate these gaps.

[0047] Optionally, in one specific embodiment, the aluminum powder includes 85-90% by mass micron-sized spherical aluminum powder and 10-15% by mass nano-sized spherical aluminum powder.

[0048] Optionally, in one specific embodiment, the aluminum powder includes micron-sized spherical aluminum powder with a purity of three nines, a mass fraction of 85-95%, and a D50 of 5-6 μm, and nano-spherical aluminum powder with a purity of three nines, a mass fraction of 5-15%, and a D50 of 7-9 nm.

[0049] Optionally, in one embodiment, the above-mentioned organic additives include one or more of fatty alcohol ether phosphates, aluminate coupling agents, silane coupling agents, zirconium aluminate coupling agents, lauryl phosphates, silicone oil, diesters, lauryl phosphate mixtures, DIG655, and BYK109.

[0050] In the IBC battery aluminum paste provided in this embodiment of the invention, the organic binder includes a polymer resin and an organic solvent; wherein, the polymer resin is dissolved in the organic solvent, so that the organic solvent can act as an organic binder, that is, the paste can act as a binder for powder after drying.

[0051] Optionally, in one embodiment, the polymer in the organic adhesive has a mass fraction of 9-14%, and the organic solvent in the organic adhesive has a mass fraction of 86-91%.

[0052] Optionally, in some embodiments, the polymer in the organic adhesive has a mass fraction of 10-12%, and the organic solvent in the organic adhesive has a mass fraction of 88-90%.

[0053] Optionally, in one embodiment, the above-mentioned polymer is one or more of ethyl cellulose-N20, ethyl cellulose N-50, and ethyl cellulose-N100;

[0054] The aforementioned organic solvents include at least four of the following: benzyl alcohol, diethyl phthalate, terpineol, butylcarbamate, butylcarbamate acetate, tributyl citrate, Span 85, and 12-ol ester.

[0055] Optionally, in one embodiment, the glass powder, by weight, is obtained by sintering and pulverizing 15-25 parts Bi₂O₃, 6-8 parts Al₂O₃, 10-25 parts Pb₂O₅, 5-15 parts ZnO, 10-15 parts Sb₂O₅, 5-15 parts V₂O₅, 12-20 parts TiO₂, and 12-20 parts BaO. The D50 of the glass powder is 1.2-1.8 μm. A D50 less than 1.2 μm indicates excessive glass activity, while a D50 greater than 1.8 μm indicates insufficient glass activity. Optionally, the D50 of the glass powder is 1.5-1.8 μm.

[0056] Among them, Bi2O3 forms the main network structure, while ZnO can break the network structure and promote glass crystallization. Al2O3 can adjust the stability of the glass and increase its viscosity. Sb2O5 is used to clarify and homogenize the glass melt. Pb2O5 reacts with silicon nitride to produce lead, nitrogen and silicon dioxide. V2O5 and TiO2 can assist Pb2O5 and silicon nitride in their reaction. BaO is used for local crystallization.

[0057] This invention also provides a method for preparing aluminum paste for IBC batteries, wherein, as shown in the embodiments of the present invention... Figure 1 As shown, steps 101 to 102 are included:

[0058] Step 101: Mix aluminum powder, boron powder, indium powder, organic binder and doped glass powder to obtain a mixture; wherein the dopant of the doped glass powder is one or more of lead and bismuth;

[0059] Step 102: After grinding the mixture, add organic additives to obtain IBC battery aluminum paste.

[0060] In step 101 above, 70-76% of aluminum powder, 0.05-0.1% of boron powder, 0.5-1% of indium powder, 20.6-27.95% of organic binder, and 1.2-1.8% of doped glass powder are weighed and mixed, and dispersed using a disperser to obtain the above mixture.

[0061] Optionally, in one embodiment, in step 101 above, the organic binder, nano-sized aluminum powder, boron powder and indium powder are first mixed and dispersed using a disperser, and then micron-sized aluminum powder and doped glass powder are added and dispersed again using a disperser, and then ground to obtain the above mixture.

[0062] In step 102 above, after grinding the above mixture, 0.3 to 0.5% of organic additives by weight of the total raw materials are added. After high-speed dispersion, a positive grid line that can be formed to contact the P+ region on the back of the IBC battery without laser grooving is obtained, thus avoiding damage to the passivation layer caused by laser grooving.

[0063] In this embodiment of the invention, indium powder is added to the aluminum paste, and lead and / or bismuth-doped glass powder is used. Indium, like aluminum, is a Group 3 element and has similar chemical properties. Indium, lead, and bismuth have etching properties and high density. After a passivation layer is formed on the back of the silicon wafer, it is directly printed onto the passivation layer area above the p+ doped region, and then sintered at high temperature. This allows it to contact the p+ doped region and form the positive electrode grid line, eliminating the need for a secondary laser grooving step and avoiding damage to the passivation layer caused by secondary laser grooving, thus improving the open-circuit voltage of the battery. At the same time, during the sintering process, it descends to the silicon surface faster than aluminum, increasing the probability of In-Si contact, reducing the contact resistance between the paste and the battery, and maintaining a high open-circuit voltage. In addition, by using indium to replace part of the aluminum powder, the aluminum content is reduced, which helps to reduce the side effects of Al, weakening the Al-Si reaction, resulting in shallower silver-aluminum corrosion pits and reduced recombination, thereby improving the open-circuit voltage and efficiency of the battery.

[0064] Optionally, in the preparation method provided in the embodiments of the present invention, the boron powder is a micron-sized boron-aluminum alloy and / or a micron-sized elemental boron. Micron-sized boron-aluminum alloy and micron-sized elemental boron have the characteristics of high tap density, low oxygen content, and high activity. By adding this micron-sized boron-aluminum alloy powder and / or micron-sized elemental boron, the aluminum paste can quickly form a good alloy with silicon under relatively low sintering temperature conditions, reducing the contact resistivity between the front-side aluminum grid and the battery.

[0065] Optionally, in the preparation method provided in the embodiments of the present invention, the organic additive includes two or more of the following: fatty alcohol ether phosphate, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, lauryl phosphate, silicone oil, diester, and lauryl phosphate.

[0066] Optionally, in the preparation method provided in the embodiments of the present invention, the silver powder includes 95-98% by mass micron-sized spherical silver powder and 2-5% by mass nano-sized spherical silver powder.

[0067] Optionally, in the preparation method provided in the embodiments of the present invention, the aluminum powder includes 85-95% by mass micron-sized spherical aluminum powder and 5-15% by mass nano-sized spherical aluminum powder.

[0068] Optionally, in the preparation method provided in the embodiments of the present invention, the doped glass powder is obtained by sintering and pulverizing 15-25 parts Bi2O3, 6-8 parts Al2O3, 10-25 parts Pb2O5, 5-15 parts ZnO, 10-15 parts Sb2O5, 5-15 parts V2O5, 12-20 parts TiO2, and 12-20 parts BaO, by mass.

[0069] Optionally, in the preparation method provided in the embodiments of the present invention, the indium powder is micron-sized elemental indium.

[0070] Optionally, in the preparation method provided in the embodiments of the present invention, the organic additives include one or more of fatty alcohol ether phosphates, aluminate coupling agents, silane coupling agents, zirconium aluminate coupling agents, lauryl phosphates, silicone oil, diesters, and mixtures of lauryl phosphates.

[0071] Optionally, in the preparation method provided in the embodiments of the present invention, the organic binder includes a polymer resin and an organic solvent;

[0072] The polymer in the organic adhesive has a mass fraction of 9-14%;

[0073] The organic solvent has a mass fraction of 86-91% in the organic adhesive.

[0074] Optionally, in the preparation method provided in the embodiments of the present invention, the polymer is ethyl cellulose-N2O;

[0075] The organic solvent includes at least four of the following: benzyl alcohol, diethyl phthalate, terpineol, butylcarbiol, butylcarbiol acetate, tributyl citrate, Span 85, and ester twelve.

[0076] Optionally, in the preparation method provided in the embodiments of the present invention, the aluminum powder includes 85-90% by mass micron-sized spherical aluminum powder and 10-15% by mass nano-sized spherical aluminum powder.

[0077] This invention also proposes a method for preparing an IBC battery, wherein, as... Figure 2 As shown, steps 201 to 203 are included:

[0078] Step 201: After forming interdigitated n+ doped regions and p+ doped regions on the back side of the silicon wafer, a passivation layer is formed on the surface of the n+ doped regions and p+ doped regions.

[0079] Step 202: Print aluminum paste in the first region of the passivation layer and silver paste in the second region of the passivation layer; the projection of the first region is within the p+ doped region and the projection of the second region is within the n+ doped region; wherein, the components constituting the aluminum paste include organic additives, boron powder, aluminum powder, indium powder, organic binder and doped glass powder, and the dopant of the doped glass powder is one or more of lead and bismuth;

[0080] Step 203: The P-type silicon wafer with aluminum paste printed in the first region and silver paste printed in the second region is subjected to high-temperature sintering to obtain an IBC battery.

[0081] In step 201 above, the silicon wafer is first texturized with an alkaline agent, and then interdigitated n+ doped regions and p+ doped regions are formed on the back side of the silicon wafer. Then, a silicon oxide layer or silicon nitride layer is deposited to cover the entire back side of the silicon wafer as the passivation layer.

[0082] In step 202 above, the silicon wafer after the passivation layer is formed is screen-printed to prepare electrode gate lines. Specifically, the aluminum paste is printed in the first region of the passivation layer on the back of the silicon wafer. The projection of this first region is within the p+ doped region to form a positive gate line that is connected to the p+ doped region. At the same time, silver paste is also printed in the second region of the back passivation layer. The projection of this second region is within the n+ doped region to form a negative gate line that is spaced apart from the positive gate line. The silver paste can be a conventional silver paste.

[0083] In step 203 above, indium powder is added to the aluminum paste, and lead and / or bismuth-doped glass powder is used. Indium, like aluminum, is a Group 3 element and has similar chemical properties. Indium, lead, and bismuth have etching properties and high density. After the passivation layer is formed on the back of the silicon wafer, it is directly printed onto the passivation layer area above the p+ doped region and then sintered at high temperature. This allows it to contact the p+ doped region and form the positive electrode grid line without the need for secondary laser grooving, thus avoiding damage to the passivation layer caused by secondary laser grooving and improving the open-circuit voltage of the battery. At the same time, it descends to the silicon surface faster than aluminum during sintering, increasing the probability of In-Si contact, reducing the contact resistance between the paste and the battery, and maintaining a high open-circuit voltage. In addition, by using indium to replace part of the aluminum powder, the aluminum content is reduced, which helps to reduce the side effects of Al, weakening the Al-Si reaction, resulting in shallower silver-aluminum corrosion pits and reduced recombination, thereby improving the open-circuit voltage and efficiency of the battery.

[0084] The silicon wafers mentioned above can be N-type or P-type silicon wafers.

[0085] For example, when the silicon wafer is a P-type silicon wafer, step 101 specifically includes:

[0086] (1) Take a P-type silicon wafer and use low pressure chemical vapor deposition (LPCVD) to form an ultrathin silicon oxide layer on the back side of the P-type silicon wafer as an ultrathin tunneling oxide layer. Then, prepare a polycrystalline silicon layer on both sides with a thickness that meets the passivation effect. Among them, because the preparation of the polycrystalline silicon layer on both sides is beneficial to the subsequent removal of the polycrystalline silicon layer on the front side, it is less likely to cause the two extreme cases of over-removal or under-removal, and the yield is better controlled.

[0087] (2) After the polycrystalline silicon layer is prepared, the silicon wafer is sent into the furnace tube to dope the polycrystalline silicon layer with phosphorus to form an n+ doped region.

[0088] (3) Laser grooving is performed on the back side of the silicon wafer to expose the p+ doped region, forming an interdigitated n+ doped region and p+ doped region, and then the front polycrystalline silicon layer is removed by wet method.

[0089] (4) A passivation layers are deposited on the entire front and back of the product using atomic layer deposition (ALD) technology to form field passivation; after forming the aluminum oxide film, an anti-reflection film is first deposited on the front of the battery, and then an anti-reflection film is deposited on the back to further improve the passivation effect of the battery cell.

[0090] The present invention will be described in detail below through embodiments.

[0091] Example 1

[0092] (1) Provide aluminum paste a1: by mass, IBC battery aluminum paste a1 is composed of 0.4 parts organic additives, 72 parts aluminum powder, 0.5 parts elemental indium, 0.06 parts boron powder, 25.54 parts organic binder and 1.5 parts doped glass powder;

[0093] The organic additives include a mixture of lauryl phosphate and lauryl alcohol phosphate; the aluminum powder includes micron-sized spherical aluminum powder with a purity of 99.99% and a mass fraction of 92%, and nano-spherical aluminum powder with a purity of 99.99% and a mass fraction of 8%; the organic binder includes 10% ethyl cellulose-N100 and 90% organic solvent, the organic solvent including butyl carbolic acid, butyl carbolic acid acetate, Span 85 and 12-ethylhexyl alcohol ester;

[0094] The doped glass powder was obtained by sintering and pulverizing 20Bi2O3, 6 parts Al2O3, 12 parts Pb2O5, 10 parts ZnO, 12 parts Sb2O5, 10 parts V2O5, 15 parts TiO2, and 15 parts BaO.

[0095] (2) After forming a silicon oxide layer and a polycrystalline silicon layer sequentially on the back side of a P-type silicon wafer with a specification of 182mm×182mm, phosphorus doping is performed on the back polycrystalline silicon layer.

[0096] (3) Laser grooving is performed on the back side of the phosphorus-doped P-type silicon wafer to form interdigitated n+ doped regions and p+ doped regions, and the front polycrystalline silicon layer is removed.

[0097] (4) After removing the front polysilicon layer and sequentially forming a double-sided aluminum oxide layer, a front silicon nitride layer, and a back silicon nitride layer, the aluminum paste a1 is printed on the back silicon nitride opposite the p+ doped region by a 360-mesh screen, and silver paste is printed on the back silicon nitride opposite the n+ doped region.

[0098] (5) The silicon wafer was sintered at high temperature in a sintering furnace, with a peak sintering temperature of 772°C, to obtain a P-type IBC cell.

[0099] The electrical properties tested after sintering are as follows: open circuit voltage 0.7185V, short circuit current 13.825A, fill power 83.5%, and photoelectric conversion efficiency 25.122%.

[0100] Example 2

[0101] (1) Provide aluminum paste a2: by mass, IBC battery aluminum paste a1 is composed of 0.4 parts organic additives, 75 parts aluminum powder, 1 part elemental indium, 0.1 parts boron powder, 22 parts organic binder and 1.5 parts doped glass powder;

[0102] The organic additives include a mixture of lauryl phosphate and lauryl phosphate; the aluminum powder includes micron-sized spherical aluminum powder with a purity of 99.99% and a mass fraction of 90%, and nano-spherical aluminum powder with a purity of 99.99% and a mass fraction of 10%; the organic binder includes 10% ethyl cellulose-N100 and 90% organic solvent, the organic solvent including butyl carbolic acid, butyl carbolic acid acetate, Span 85 and 12-ethylhexyl alcohol ester;

[0103] The doped glass powder was obtained by sintering and pulverizing 20Bi2O3, 6 parts Al2O3, 12 parts Pb2O5, 10 parts ZnO, 12 parts Sb2O5, 10 parts V2O5, 15 parts TiO2, and 15 parts BaO.

[0104] (2) After forming a silicon oxide layer and a polycrystalline silicon layer sequentially on the back side of a P-type silicon wafer with a specification of 182mm×182mm, phosphorus doping is performed on the back polycrystalline silicon layer.

[0105] (3) Laser grooving is performed on the back side of the phosphorus-doped P-type silicon wafer to form interdigitated n+ doped regions and p+ doped regions, and the front polycrystalline silicon layer is removed.

[0106] (4) After removing the front polysilicon layer and sequentially forming a double-sided aluminum oxide layer, a front silicon nitride layer, and a back silicon nitride layer, the aluminum paste a2 is printed on the back silicon nitride opposite the p+ doped region by a 360-mesh screen, and silver paste is printed on the back silicon nitride opposite the n+ doped region.

[0107] (5) The silicon wafer was sintered at high temperature in a sintering furnace, with a peak sintering temperature of 772°C, to obtain a P-type IBC cell.

[0108] The electrical properties tested after sintering are as follows: open circuit voltage 0.719V, short circuit current 13.865A, fill power 83.2%, and photoelectric conversion efficiency 25.12%.

[0109] Example 3

[0110] (1) Provide aluminum paste a3: by mass, IBC battery aluminum paste a3 is composed of 0.4 parts organic additives, 72 parts aluminum powder, 0.6 parts elemental indium, 0.06 parts boron powder, 25.54 parts organic binder and 1.4 parts doped glass powder;

[0111] The organic additives include lauryl phosphate and lauryl phosphate; the aluminum powder includes micron-sized spherical aluminum powder with a purity of 99.99% and a mass fraction of 92%, and nano-spherical aluminum powder with a purity of 99.99% and a mass fraction of 8%; the organic binder includes 10% ethyl cellulose-N100 and 90% organic solvent, the organic solvent including butyl carbolic acid, butyl carbolic acid acetate, Span 85 and 12-ethylhexyl alcohol ester;

[0112] The doped glass powder was obtained by sintering and pulverizing 20Bi2O3, 6 parts Al2O3, 12 parts Pb2O5, 10 parts ZnO, 12 parts Sb2O5, 10 parts V2O5, 15 parts TiO2, and 15 parts BaO.

[0113] (2) After forming a silicon oxide layer and a polysilicon layer on the back side of an N-type silicon wafer with a specification of 182mm×182mm, boron doping is performed on the back polysilicon layer.

[0114] (3) Laser grooving is performed on the back side of the boron-doped N-type silicon wafer to form interdigitated n+ doped regions and p+ doped regions, and the front polysilicon layer is removed.

[0115] (4) After removing the front polysilicon layer and sequentially forming a double-sided aluminum oxide layer, a front silicon nitride layer, and a back silicon nitride layer, the aluminum paste a3 is printed on the back silicon nitride opposite the p+ doped region by a 360-mesh screen, and silver paste is printed on the back silicon nitride opposite the n+ doped region.

[0116] (5) The silicon wafer was sintered at high temperature in a sintering furnace, with a peak sintering temperature of 772°C, to obtain an N-type IBC cell.

[0117] The electrical properties tested after sintering are as follows: open circuit voltage 0.720V, short circuit current 13.855A, fill power 83.15%, and photoelectric conversion efficiency 25.121%.

[0118] Comparative Example 1

[0119] (1) Provide aluminum paste b1: by mass, IBC battery aluminum paste b1 is composed of 0.4 parts organic additives, 76 parts aluminum powder, 0.1 parts boron powder, 22 parts organic binder and 1.5 parts doped glass powder;

[0120] The organic additives include lauryl phosphate and lauryl alcohol phosphate; the aluminum powder includes micron-sized spherical aluminum powder with a purity of 99.99% and a mass fraction of 90%, and nano-spherical aluminum powder with a purity of 99.99% and a mass fraction of 10%; the organic binder includes 10% ethyl cellulose-N100 and 90% organic solvent, the organic solvent including butyl carbolic acid, butyl carbolic acid acetate, Span 85 and 12-ethylhexyl alcohol ester;

[0121] The doped glass powder was obtained by sintering and pulverizing 20Bi2O3, 6 parts Al2O3, 12 parts MgO, 10 parts ZnO, 12 parts Sb2O5, 10 parts V2O5, 15 parts TiO2, and 15 parts BaO.

[0122] (2) After forming a silicon oxide layer and a polycrystalline silicon layer sequentially on the back side of a P-type silicon wafer with a specification of 182mm×182mm, phosphorus doping is performed on the back polycrystalline silicon layer.

[0123] (3) Laser grooving is performed on the back side of the phosphorus-doped P-type silicon wafer to form interdigitated n+ doped regions and p+ doped regions, and the front polycrystalline silicon layer is removed.

[0124] (4) After removing the front polysilicon layer and sequentially forming a double-sided aluminum oxide layer, a front silicon nitride layer, and a back silicon nitride layer, the aluminum paste b1 is printed on the back silicon nitride opposite the p+ doped region by a 360-mesh screen, and silver paste is printed on the back silicon nitride opposite the n+ doped region.

[0125] (5) The silicon wafer is sintered at high temperature in a sintering furnace, with a peak sintering temperature of 772°C, to obtain an IBC cell.

[0126] The electrical properties tested after sintering are as follows: open circuit voltage is 0.7155V, short circuit current is 13.845A, fill power is 83.32%, and photoelectric conversion efficiency is 25.000%.

[0127] Comparative Example 2

[0128] (1) Provide aluminum paste b2: by mass, IBC battery aluminum paste b2 is composed of 0.4 parts organic additives, 72.6 parts elemental indium, 0.06 parts boron powder, 25.54 parts organic binder and 1.4 parts doped glass powder;

[0129] The organic additives include lauryl phosphate and lauryl alcohol phosphate; the aluminum powder includes micron-sized spherical aluminum powder with a purity of 99.99% and a mass fraction of 90%, and nano-spherical aluminum powder with a purity of 99.99% and a mass fraction of 10%; the organic binder includes 10% ethyl cellulose-N100 and 90% organic solvent, the organic solvent including butyl carbolic acid, butyl carbolic acid acetate, Span 85 and 12-ethylhexyl alcohol ester;

[0130] The doped glass powder was obtained by sintering and pulverizing 20Bi2O3, 6 parts Al2O3, 12 parts MgO, 10 parts ZnO, 12 parts Sb2O5, 10 parts V2O5, 15 parts TiO2, and 15 parts BaO.

[0131] (2) After forming a silicon oxide layer and a polysilicon layer on the back side of an N-type silicon wafer with a specification of 182mm×182mm, boron doping is performed on the back polysilicon layer.

[0132] (3) Laser grooving is performed on the back side of the boron-doped N-type silicon wafer to form interdigitated n+ doped regions and p+ doped regions, and the front polysilicon layer is removed.

[0133] (4) After removing the front polysilicon layer and sequentially forming a double-sided aluminum oxide layer, a front silicon nitride layer, and a back silicon nitride layer, the aluminum paste b1 is printed on the back silicon nitride opposite the p+ doped region by a 360-mesh screen, and silver paste is printed on the back silicon nitride opposite the n+ doped region.

[0134] (5) The silicon wafer was sintered at high temperature in a sintering furnace, with a peak sintering temperature of 772°C, to obtain a P-type IBC cell.

[0135] The electrical properties tested after sintering are as follows: open circuit voltage is 0.7158V, short circuit current is 13.825A, fill power is 83.45%, and photoelectric conversion efficiency is 25.013%.

[0136] Comparing Examples 1 and 2 with Comparative Example 1, and comparing Example 3 with Comparative Example 2, it can be seen that by using aluminum paste doped with indium, lead, and bismuth to form the P+ emitter, the back electrode grid line can be formed without laser grooving. Furthermore, the recombination rate and recombination degree of the battery are greatly improved, the battery efficiency is increased by 0.1%, and the opening voltage is increased by 3mV.

[0137] In summary, in this embodiment, by adding indium powder to the aluminum paste and using lead and / or bismuth-doped glass powder, indium, like aluminum, belongs to Group 3 and has similar chemical properties. Furthermore, indium, lead, and bismuth have etching properties and high density. After forming a passivation layer on the back of the silicon wafer, the passivation layer is directly printed onto the p+ doped region, followed by high-temperature sintering. This allows for contact with the p+ doped region and the formation of the positive electrode grid line, eliminating the need for a secondary laser grooving step and preventing damage to the passivation layer. This improves the battery's open-circuit voltage. Simultaneously, During sintering, Indium descends to the silicon surface more rapidly than aluminum, increasing the probability of In-Si contact, reducing the contact resistance between the paste and the cell, and maintaining a higher open-circuit voltage. In addition, by using indium to replace part of the aluminum powder, the aluminum content is reduced, which helps to reduce the side effects of Al, weakening the Al-Si reaction, resulting in shallower silver-aluminum corrosion pits and reduced recombination, thereby improving the open-circuit voltage and efficiency of the cell. Thus, it solves the problem that existing IBC cell aluminum pastes require laser grooving of the P+ region before printing into positive electrode grid lines, which leads to a decrease in the open-circuit voltage of the cell.

[0138] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0139] The above provides a detailed description of the IBC battery aluminum paste, the IBC battery, and its preparation method provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An aluminum paste for IBC batteries, characterized in that, The components constituting the aluminum paste include organic additives, boron powder, aluminum powder, indium powder, organic binder, and doped glass powder, wherein the dopant of the doped glass powder is one or more of lead and bismuth. The doped glass powder, by weight, is obtained by sintering and pulverizing 15-25 parts Bi2O3, 6-8 parts Al2O3, 10-25 parts Pb2O5, 5-15 parts ZnO, 10-15 parts Sb2O5, 5-15 parts V2O5, 12-20 parts TiO2, and 12-20 parts BaO. The mass fractions of the organic additives, boron powder, aluminum powder, indium powder, organic binder, and doped glass powder are 0.3~0.5%, 0.05~0.1%, 70~76%, 0.5~1%, 20.6~27.95%, and 1.2~1.8%, respectively.

2. The IBC battery aluminum paste according to claim 1, characterized in that, The indium powder is micron-sized elemental indium.

3. The IBC battery aluminum paste according to claim 1, characterized in that, The organic additives include one or more of the following: fatty alcohol ether phosphate, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, silicone oil, diester, and a mixture of lauryl phosphate.

4. The IBC battery aluminum paste according to claim 1, characterized in that, The organic binder includes a polymer resin and an organic solvent; The polymer in the organic adhesive has a mass fraction of 9-14%; The organic solvent has a mass fraction of 86-91% in the organic adhesive.

5. The IBC battery aluminum paste according to claim 4, characterized in that, The polymer is ethyl cellulose-N2O; The organic solvent includes at least four of the following: benzyl alcohol, diethyl phthalate, terpineol, butyl carbiol, butyl carbiol acetate, tributyl citrate, Span 85, and ester twelve.

6. The IBC battery aluminum paste according to claim 1, characterized in that, The aluminum powder includes micron-sized spherical aluminum powder and nano-sized spherical aluminum powder.

7. A method for preparing an IBC battery, characterized in that, include: After forming interdigitated n+ doped regions and p+ doped regions on the back side of the silicon wafer, a passivation layer is formed on the surface of the n+ doped regions and p+ doped regions. Aluminum paste is printed in the first region of the passivation layer, and silver paste is printed in the second region of the passivation layer; The projection of the first region is within the p+ doped region, and the projection of the second region is within the n+ doped region; wherein, the components constituting the aluminum paste include organic additives, boron powder, aluminum powder, indium powder, organic binder, and doped glass powder, wherein the dopant of the doped glass powder is one or more of lead and bismuth; by mass parts, the doped glass powder is obtained by sintering and pulverizing 15~25 parts Bi2O3, 6~8 parts Al2O3, 10~25 parts Pb2O5, 5~15 parts ZnO, 10~15 parts Sb2O5, 5~15 parts V2O5, 12~20 parts TiO2, and 12~20 parts BaO; the mass fractions of the organic additives, boron powder, aluminum powder, indium powder, organic binder, and doped glass powder are 0.3~0.5%, 0.05~0.1%, 70~76%, 0.5~1%, 20.6~27.95%, and 1.2~1.8%, respectively; IBC cells are prepared by high-temperature sintering of a P-type silicon wafer with aluminum paste printed in the first region and silver paste printed in the second region.

8. An IBC battery, characterized in that, It is prepared by the method described in claim 7.

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