N-type topcon cell front-side silver-aluminum paste, preparation method thereof and cell

Abstract

The embodiment of the present application provides a kind of N type TOPCon cell front silver aluminum paste and its preparation method and cell, wherein, the N type TOPCon cell front silver aluminum paste provided in the embodiment of the present application includes aluminum powder, silver powder, nano alloy powder, organic binder, glass powder and organic additive, wherein the nano alloy powder is one or more of nano silver aluminum alloy powder, nano aluminum boron alloy powder and nano aluminum silicon alloy powder.In nano silver aluminum alloy powder, nano aluminum boron alloy powder and nano aluminum silicon alloy powder, all have the characteristics of nano size particle size, high tap density, low oxygen content and high activity, so that the front silver aluminum paste added with the nano alloy powder can quickly form a good alloy with silicon at a lower sintering temperature, reduce the contact resistivity of front silver aluminum fine grid and cell, not only avoid the appearance of top needle print during EL test, but also improve the filling of cell and the efficiency of cell.

Description

Technical Field

[0001] This invention relates to the field of crystalline silicon solar cell manufacturing technology, and in particular to an N-type TOPCon cell front-side silver-aluminum paste, its preparation method, and the cell itself. Background Technology

[0002] Currently, N-type TOPCon cells in crystalline silicon solar cells are widely used due to their advantages such as low degradation, significant overall cell efficiency, and high power generation.

[0003] To improve battery efficiency, most existing N-type TOPCon batteries adopt a high-resistivity dense grid technology, which has a low front diffusion concentration. This increases the contact resistivity between the front silver-aluminum grid and the cell, causing pin marks of different sizes to appear at the contact point between the front silver-aluminum grid and the sintered mesh belt during electroluminescence (EL) testing. This affects battery grade, yield, and economic benefits. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a silver-aluminum paste on the front side of an N-type TOPCon battery, a method for preparing the paste, and the battery itself, so as to solve the problem that existing N-type TOPCon batteries are prone to pin marks during EL testing due to the use of high-resistivity dense grid technology.

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

[0006] This invention proposes a silver-aluminum paste for the front side of an N-type TOPCon battery, wherein the components of the silver-aluminum paste include aluminum powder, silver powder, nano-alloy powder, organic binder, glass powder, and organic additives, wherein the nano-alloy powder is one or more of nano-silver-aluminum alloy powder, nano-aluminum-boron alloy powder, and nano-aluminum-silicon alloy powder.

[0007] Furthermore, in the silver-aluminum paste on the front side of the N-type TOPCon battery, the mass fractions of silver powder, aluminum powder, nano-alloy powder, organic binder, glass powder, and organic additives are 78-84%, 1-3%, 0.1-0.5%, 9.7-19.6%, 1-2%, and 0.3-0.8%, respectively.

[0008] Furthermore, in the N-type TOPCon battery front-side silver-aluminum paste, the organic additives include one or more of the following: DIG655, BYK109, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, lauryl phosphate, silicone oil, and a mixture of diesters.

[0009] Furthermore, in the N-type TOPCon battery front-side silver-aluminum paste, the silver powder includes micron-sized spherical silver powder and nano-sized spherical silver powder, and the aluminum powder includes micron-sized spherical aluminum powder and nano-sized spherical aluminum powder.

[0010] Furthermore, in the N-type TOPCon battery front silver-aluminum paste, the organic binder includes a polymer and an organic solvent;

[0011] The polymer in the organic binder has a mass fraction of 7-11%;

[0012] The organic solvent has a mass fraction of 89-93% in the organic binder.

[0013] Furthermore, in the silver-aluminum paste on the front side of the N-type TOPCon battery, the organic solvent is four or more of the following: terpineol, butylcarbohydrate, butylcarbohydrate acetate, tributyl citrate, Span 85, ester dodecyl alcohol, turpentine, triethyl citrate, acetylated tributyl citrate, ester dodecyl alcohol, lecithin, and diethylene glycol ethyl ether.

[0014] Furthermore, in the silver-aluminum paste on the front side of the N-type TOPCon battery, the D50 of the glass powder is 1.2 to 1.8 μm.

[0015] Furthermore, in the silver-aluminum paste on the front side of the N-type TOPCon battery, the glass powder is obtained by sintering and pulverizing 20-25% Bi2O3, 6-8% Al2O3, 10-12% SiO2, 5-29% PbO, 15-20% Sb2O5, 5-8% B2O3, 15-22% TiO2, and 2-4% V2O5 by mass fraction.

[0016] This invention also proposes a method for preparing a silver-aluminum paste on the front side of an N-type TOPCon battery, comprising:

[0017] Silver powder, aluminum powder, nano alloy powder, organic binder and glass powder are mixed to obtain a mixture, wherein the nano alloy powder is one or more of nano silver aluminum alloy powder, nano aluminum boron alloy powder and nano-sized aluminum silicon alloy powder;

[0018] After grinding the mixture, organic additives are added to obtain the front silver-aluminum paste for N-type TOPCon batteries.

[0019] The present invention also proposes an N-type solar cell, wherein multiple grid lines are attached to the front side of the N-type solar cell, and the grid lines are prepared from the aforementioned silver-aluminum paste.

[0020] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0021] In this embodiment of the invention, the provided N-type TOPCon battery front-side silver-aluminum paste comprises aluminum powder, silver powder, nano-alloy powder, organic binder, glass powder, and organic additives. The nano-alloy powder is one or more of nano-silver-aluminum alloy powder, nano-aluminum-boron alloy powder, and nano-aluminum-silicon alloy powder. Because nano-silver-aluminum alloy powder, nano-aluminum-boron alloy powder, and nano-aluminum-silicon alloy powder all possess nanoscale particle size, high tap density, low oxygen content, and high activity, the front-side silver-aluminum paste with added nano-alloy powder can quickly form a good alloy with silicon at a relatively low sintering temperature. This reduces the contact resistivity between the front-side silver-aluminum grid and the battery, not only avoiding pin marks during EL testing but also improving battery filling and efficiency.

[0022] 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

[0023] Figure 1 This is a flowchart of a method for preparing silver-aluminum paste on the front side of an N-type TOPCon battery according to an embodiment of the present invention;

[0024] Figure 2 This is a flowchart of a method for preparing silver-aluminum paste on the front side of an N-type TOPCon battery according to another embodiment of the present invention. Detailed Implementation

[0025] 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.

[0026] The applicant of this invention discovered that most existing N-TOPCon batteries employ a high-resistivity, dense-grid design to improve battery efficiency, but this also results in a low front-side diffusion concentration. This low front-side diffusion concentration leads to increased contact resistivity between the front-side silver-aluminum grid and the battery cell, causing black, pin-like marks of varying sizes to appear at the contact point between the front-side silver-aluminum grid and the sintered mesh during EL testing. The presence of these pin marks not only degrades the battery but also affects its yield and economic efficiency. While increasing the sintering temperature can typically solve the problem of severe pin marks, this significantly reduces the efficiency of N-TOPCon batteries, contradicting the original intention of using a high-resistivity, dense-grid design.

[0027] To address the aforementioned problems, this invention provides an N-type TOPCon battery front-side silver-aluminum paste. The components of the silver-aluminum paste include aluminum powder, silver powder, nano-alloy powder, organic binder, glass powder, and organic additives. The nano-alloy powder is one or more of nano-silver-aluminum alloy powder, nano-aluminum-boron alloy powder, and nano-aluminum-silicon alloy powder.

[0028] The main components are silver powder and aluminum powder; glass powder is an inorganic binder that melts into a liquid state at high temperatures and solidifies upon cooling, thus acting as an adhesive; organic binders ensure overall bonding; organic additives reduce the overall viscosity of the silver paste; because nano-silver-aluminum alloy powder, nano-aluminum-boron alloy powder, and nano-aluminum-silicon alloy powder have the characteristics of nano-sized particles, high tap density, low oxygen content, and high activity, by adding this nano-alloy powder, the front-side silver-aluminum paste can quickly form a good alloy with silicon at a lower sintering temperature, reducing the contact resistivity between the front-side silver-aluminum grid and the battery. This not only avoids pin marks during EL testing but also improves battery filling and efficiency, thus effectively solving the problem of pin marks easily appearing during EL testing in existing N-type TOPCon batteries due to the use of high-resistivity dense grid technology.

[0029] Optionally, the aforementioned organic additives include one or more of the following: DIG655, BYK109, aluminate coupling agents, silane coupling agents, zirconium aluminate coupling agents, lauryl phosphate, silicone oil, and mixtures of diesters.

[0030] In the N-type TOPCon battery front-side silver-aluminum paste provided in this embodiment of the invention, the mass fractions of silver powder, aluminum powder, nano-alloy powder, organic binder, glass powder and organic additives are 78-84%, 1-3%, 0.1-0.5%, 9.7-19.6%, 1-2% and 0.3-0.8%, respectively.

[0031] For example, in the silver-aluminum paste, the mass fractions of silver powder, aluminum powder, nano-alloy powder, organic binder, glass powder and organic additives are 78%, 3%, 0.1%, 17.1%, 1% and 0.8%, respectively.

[0032] For example, in the silver-aluminum paste, the mass fractions of silver powder, aluminum powder, nano-alloy powder, organic binder, glass powder, and organic additives are 84%, 1%, 0.5%, 12.2%, 2%, and 0.3%, respectively.

[0033] For example, in the silver-aluminum paste, the mass fractions of silver powder, aluminum powder, nano-alloy powder, organic binder, glass powder and organic additives are 78%, 1%, 0.1%, 19.6%, 1% and 0.3%, respectively.

[0034] For example, in the silver-aluminum paste, the mass fractions of silver powder, aluminum powder, nano-alloy powder, organic binder, glass powder, and organic additives are 84%, 3%, 0.5%, 9.7%, 2%, and 0.8%, respectively.

[0035] For example, in the silver-aluminum paste, the mass fractions of silver powder, aluminum powder, nano-alloy powder, organic binder, glass powder, and organic additives are 80%, 2%, 0.3%, 15.7%, 1.5%, and 0.5%, respectively.

[0036] Optionally, in one embodiment, the mass fraction of aluminum powder in the silver-aluminum paste on the front side of the N-type TOPCon battery is 1-3%.

[0037] In this embodiment of the invention, the aluminum powder is composed of aluminum powder with different particle sizes (D50 = 1-5 micrometers). The use of aluminum powder with different particle sizes can effectively mitigate the interaction between the aluminum powder's activity and the glass powder, broaden the sintering temperature of the slurry, and improve the average efficiency of the battery.

[0038] In this embodiment of the invention, the glass powder includes B2O3, Al2O3, PbO, ZnO, BaO, Sb2O3, and SiO2.

[0039] Optionally, in one embodiment, the glass powder is obtained by sintering and pulverizing 20-25% Bi₂O₃, 6-8% Al₂O₃, 10-12% SiO₂, 5-29% PbO, 15-20% Sb₂O₅, 5-8% B₂O₃, 15-22% TiO₂, and 2-4% V₂O₅ by mass fraction. Bi₂O₃ forms the main network structure; Al₂O₃ adjusts glass stability and increases viscosity; PbO adjusts glass corrosivity and lowers the melting point; Sb₂O₅ is used for clarifying and homogenizing the molten glass; SiO₂ forms the glass network, promoting glass stability and increasing the melting point; TiO₂ is used for localized crystallization; and V₂O₅ is used to lower the melting point.

[0040] The D50 of the glass powder is 1.2 to 1.8 μm. If the D50 is less than 1.2 μm, the glass activity is too high, while if the D50 is greater than 1.8 μm, the glass activity is too low.

[0041] In the N-type TOPCon battery front-side silver-aluminum paste provided in this embodiment of the invention, the aluminum powder includes micron-sized spherical aluminum powder and nano-sized spherical aluminum powder, and the silver powder includes micron-sized spherical silver powder and nano-sized spherical silver powder. Specifically, the aluminum powder includes micron-sized spherical aluminum powder with a purity of 99.99% and nano-sized spherical aluminum powder with a purity of 99.99%, and the silver powder is micron-sized spherical silver powder with a purity of 99.99% and nano-sized spherical silver powder with a purity of 99.99%. In this embodiment of the invention, the silver powder is micron-sized spherical silver powder with a purity of 99.99%. Since there are gaps between the micron-sized silver powder and between the micron-sized aluminum powder, the nano-sized spherical silver powder and the nano-sized spherical aluminum powder can fill and penetrate into the gaps between the micron-sized particles.

[0042] Optionally, in one embodiment, the nano-alloy powder comprises nanoscale spherical highly active silver-aluminum alloy powder with a purity of 2:9.

[0043] In the N-type TOPCon battery front-side silver-aluminum paste provided in this embodiment of the invention, the organic binder includes a polymer and an organic solvent; wherein, the polymer is dissolved in the organic solvent, so that the organic solvent can act as an organic binder, thus enabling the paste to bind the powder after drying.

[0044] Optionally, in one embodiment, the polymer in the organic binder has a mass fraction of 7-11%; and the organic solvent in the organic binder has a mass fraction of 89-93%.

[0045] Optionally, in one embodiment, the polymer is one or more of acrylic resin or ethyl cellulose resin;

[0046] The aforementioned organic solvents are four or more of the following: terpineol, butylcarbiol, butylcarbiol acetate, tributyl citrate, Span 85, ester dodecyl alcohol, turpentine, triethyl citrate, acetylated tributyl citrate, ester dodecyl alcohol, lecithin, and diethylene glycol ethyl ether.

[0047] This invention also provides a method for preparing the front-side silver-aluminum paste for an N-type TOPCon battery, such as... Figure 1 As shown, steps 101 to 102 are included:

[0048] Step 101: Mix silver powder, aluminum powder, nano alloy powder, organic binder and glass powder to obtain a mixture, wherein the nano alloy powder is one or more of nano silver aluminum alloy powder, nano aluminum boron alloy powder and nano-sized aluminum silicon alloy powder;

[0049] Step 102: After grinding the mixture, add organic additives to obtain the front silver-aluminum paste for N-type TOPCon batteries.

[0050] In step 101 above, 78-84% of silver powder, 1-3% of aluminum powder, 0.1-0.5% of nano-alloy powder, 9.7-19.6% of organic binder, and 1-2% of glass powder are weighed and mixed, and dispersed using a disperser to obtain the above mixture.

[0051] In step 102 above, the above mixture is ground and then an organic additive accounting for 0.3 to 0.8% of the total mass of the raw materials is added. After high-speed dispersion, the high-efficiency N-TOPCon front silver-aluminum paste for improving the pin printing is obtained.

[0052] Optionally, the silver powder includes micron-sized spherical silver powder and nano-sized spherical silver powder, and the aluminum powder includes micron-sized spherical aluminum powder and nano-sized spherical aluminum powder.

[0053] Optionally, in one embodiment, step 101 includes: mixing the organic binder, nano silver powder, nano aluminum powder, and nano alloy powder, dispersing them using a disperser, adding micron-sized silver powder, micron-sized aluminum powder, and glass powder, and then dispersing them again using a disperser to obtain the mixture.

[0054] Optionally, in the above preparation method, the organic additive includes one or more of the following: DIG655, BYK109, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, lauryl phosphate, silicone oil, and a mixture of diesters.

[0055] Optionally, in the above preparation method, the silver powder includes micron-sized spherical silver powder and nano-sized spherical silver powder, and the aluminum powder includes micron-sized spherical aluminum powder and nano-sized spherical aluminum powder.

[0056] Optionally, in the above preparation method, the organic binder includes a polymer and an organic solvent;

[0057] The polymer in the organic binder has a mass fraction of 7-11%;

[0058] The organic solvent has a mass fraction of 89-93% in the organic binder.

[0059] Optionally, in the above preparation method, the organic solvent is four or more of the following: terpineol, butylcarbiol, butylcarbiol acetate, tributyl citrate, Span 85, ester dodecyl alcohol, turpentine, triethyl citrate, acetylated tributyl citrate, ester dodecyl alcohol, lecithin, and diethylene glycol ethyl ether.

[0060] Optionally, in the above preparation method, the D50 of the glass powder is 1.2 to 1.8 μm.

[0061] Optionally, in the above preparation method, the glass powder is obtained by sintering and pulverizing 20-25% Bi2O3, 6-8% Al2O3, 10-12% SiO2, 5-29% PbO, 15-20% Sb2O5, 5-8% B2O3, 15-22% TiO2, and 2-4% V2O5 by mass fraction.

[0062] This invention also provides another method for preparing the front-side silver-aluminum paste for N-type TOPCon batteries, such as... Figure 2 As shown, steps 201 to 202 are included:

[0063] Step 201: Mix nano-alloy powder, organic binder, glass powder and organic additives to obtain a mixture; wherein the nano-alloy powder is one or more of nano-silver aluminum alloy powder, nano-aluminum boron alloy powder and nano-aluminum silicon alloy powder;

[0064] Step 202: Add silver powder and aluminum powder to the mixture, disperse and grind to obtain N-type TOPCon battery front silver-aluminum paste.

[0065] In this embodiment, nano-alloy powder, organic binder, glass powder and organic additives are mixed, and then silver powder and aluminum powder are added and ground to obtain the above-mentioned high-efficiency N-TOPCon front silver-aluminum paste for improving the pin printing.

[0066] The present invention also proposes an N-type TOPCon cell, wherein the front side of the N-type solar cell is attached with multiple grid lines, which are prepared by the aforementioned silver-aluminum paste.

[0067] The present invention will be described in detail below through embodiments.

[0068] Example 1

[0069] (1) Preparation of glass powder:

[0070] Weigh out 22 parts Bi2O3, 7 parts Al2O3, 10 parts SiO2, 20 parts PbO, 18 parts Sb2O5, 5 parts B2O3, 15 parts TiO2, and 3 parts V2O5 by weight, mix them evenly with a mixer, and then sinter and pulverize to obtain glass powder with a D50 of 1.2 to 1.8 μm.

[0071] (2) Preparation of silver-aluminum paste on the front side of N-type TOPCon battery:

[0072] Weigh out 78 parts by weight of micron-sized spherical silver powder with a purity of 99.99% or higher, 4 parts of nano-sized spherical silver powder with a purity of 99.99% or higher, 1.5 parts of micron-sized spherical aluminum powder with a purity of 99.99% or higher, 0.5 parts of nano-sized spherical aluminum powder with a purity of 99.99% or higher, 0.2 parts of nano-silver aluminum alloy powder, 13.8 parts of organic binder, and 1.5 parts of glass powder. Mix them evenly using a disperser, then grind them to below 10 microns using a three-roll mill. Finally, add 0.5 parts of organic additive to obtain the N-type TOPCon battery front silver-aluminum paste.

[0073] The organic additives include lauryl phosphate and BYKl09;

[0074] The organic binder comprises 8% by weight of a high molecular weight polymer and 92% by weight of an organic solvent;

[0075] The polymer is ethyl cellulose-N50, a polymer with low sintering residual viscoelastic modulus; the organic solvents include terpineol, butyl carbolic acid, butyl carbolic acid acetate, tributyl citrate, and Span 85.

[0076] The silver-aluminum paste on the front side of the above-mentioned N-type TOPCon cell was screen-printed onto a single-crystal N-TOPCon silicon wafer with a size of 182mm×182mm using a 480-mesh screen to form a silver grid. The wafer was then sintered in a sintering furnace at a peak temperature of 766℃.

[0077] After sintering, the electrical properties were tested as follows: open circuit voltage 0.715V, short circuit current 13.731A, fill factor 83.8%, photoelectric conversion efficiency 24.919%, and EL pin printing ratio 0.02%, which is 2.32% lower than that of conventional front-side silver aluminum paste EL pin printing ratio.

[0078] Example 2

[0079] (1) Preparation of glass powder:

[0080] Weigh out 22 parts Bi2O3, 7 parts Al2O3, 10 parts SiO2, 20 parts PbO, 18 parts Sb2O5, 5 parts B2O3, 15 parts TiO2, and 3 parts V2O5 by weight, mix them evenly with a mixer, and then sinter and pulverize to obtain glass powder with a D50 of 1.2 to 1.8 μm.

[0081] (2) Preparation of silver-aluminum paste on the front side of N-type TOPCon battery:

[0082] Weigh out 78 parts by weight of micron-sized spherical silver powder with a purity of 99.99% or higher, 3 parts of nano-sized spherical silver powder with a purity of 99.99% or higher, 1.5 parts of micron-sized spherical aluminum powder with a purity of 99.99% or higher, 1 part of nano-sized spherical aluminum powder with a purity of 99.99% or higher, 0.3 parts of nano-silver aluminum alloy powder, 14.1 parts of organic binder, and 1.5 parts of glass powder. Mix them evenly using a disperser, then grind them to below 10 microns using a three-roll mill. Finally, add 0.6 parts of organic additive to obtain the silver-aluminum paste for the front side of the N-type TOPCon battery.

[0083] The organic additives include lauryl phosphate and BYKl09;

[0084] The organic binder comprises 8% by weight of a high molecular weight polymer and 92% by weight of an organic solvent;

[0085] The polymer is ethyl cellulose-N50, a polymer with low sintering residual viscoelastic modulus; the organic solvents include terpineol, butyl carbolic acid, butyl carbolic acid acetate, tributyl citrate, and Span 85.

[0086] The silver-aluminum paste on the front side of the above-mentioned N-type TOPCon cell was screen-printed onto a single-crystal N-TOPCon silicon wafer with a size of 182mm×182mm using a 480-mesh screen to form a silver grid. The wafer was then sintered in a sintering furnace at a peak temperature of 772℃.

[0087] After sintering, the electrical properties were tested as follows: open circuit voltage 0.716V, short circuit current 13.741A, fill factor 83.7%, photoelectric conversion efficiency 24.942%, and EL pin printing ratio 0.01%, which is 2.55% lower than that of conventional front-side silver aluminum paste EL pin printing ratio.

[0088] Example 3

[0089] (1) Preparation of glass powder:

[0090] Weigh out 22 parts Bi2O3, 7 parts Al2O3, 10 parts SiO2, 20 parts PbO, 18 parts Sb2O5, 5 parts B2O3, 15 parts TiO2, and 3 parts V2O5 by weight, mix them evenly with a mixer, and then sinter and pulverize to obtain glass powder with a D50 of 1.2 to 1.8 μm.

[0091] (2) Preparation of silver-aluminum paste on the front side of N-type TOPCon battery:

[0092] Weigh out 78 parts by weight of micron-sized spherical silver powder with a purity of 99.99% or higher, 3 parts of nano-sized spherical silver powder with a purity of 99.99% or higher, 1.5 parts of micron-sized spherical aluminum powder with a purity of 99.99% or higher, 1 part of nano-sized spherical aluminum powder with a purity of 99.99% or higher, 0.3 parts of nano-aluminum-boron alloy powder, 14.1 parts of organic binder, and 1.5 parts of glass powder. Mix them evenly using a disperser, then grind them to below 10 microns using a three-roll mill. Finally, add 0.6 parts of organic additives to obtain the silver-aluminum paste for the front side of the N-type TOPCon battery.

[0093] The organic additives include lauryl phosphate and BYKl09;

[0094] The organic binder comprises 8% by weight of a high molecular weight polymer and 92% by weight of an organic solvent;

[0095] The polymer is ethyl cellulose-N50, a polymer with low sintering residual viscoelastic modulus; the organic solvents include terpineol, butyl carbolic acid, butyl carbolic acid acetate, tributyl citrate, and Span 85.

[0096] The silver-aluminum paste on the front side of the above-mentioned N-type TOPCon cell was screen-printed onto a single-crystal N-TOPCon silicon wafer with a size of 182mm×182mm using a 480-mesh screen to form a silver grid. The wafer was then sintered in a sintering furnace at a peak temperature of 765℃.

[0097] After sintering, the electrical properties were tested as follows: open circuit voltage 0.7165V, short circuit current 13.685A, fill factor 83.85%, photoelectric conversion efficiency 24.903%, and EL pin printing ratio 0.01%, which is 2.28% lower than that of conventional front-side silver aluminum paste EL pin printing ratio.

[0098] Example 4

[0099] (1) Preparation of glass powder:

[0100] Weigh out 22 parts Bi2O3, 7 parts Al2O3, 10 parts SiO2, 20 parts PbO, 18 parts Sb2O5, 5 parts B2O3, 15 parts TiO2, and 3 parts V2O5 by weight, mix them evenly with a mixer, and then sinter and pulverize to obtain glass powder with a D50 of 1.2 to 1.8 μm.

[0101] (2) Preparation of silver-aluminum paste on the front side of N-type TOPCon battery:

[0102] Weigh out 78 parts by weight of micron-sized spherical silver powder with a purity of 99.99% or higher, 3 parts of nano-sized spherical silver powder with a purity of 99.99% or higher, 1.5 parts of micron-sized spherical aluminum powder with a purity of 99.99% or higher, 1 part of nano-sized spherical aluminum powder with a purity of 99.99% or higher, 0.3 parts of nano-sized aluminum-silicon alloy powder, 14.1 parts of organic binder, and 1.5 parts of glass powder. Mix them evenly using a disperser, then grind them to below 10 microns using a three-roll mill. Finally, add 0.6 parts of organic additives to obtain the silver-aluminum paste for the front side of the N-type TOPCon battery.

[0103] The organic additives include lauryl phosphate and BYKl09;

[0104] The organic binder comprises 8% by weight of a high molecular weight polymer and 92% by weight of an organic solvent;

[0105] The polymer is ethyl cellulose-N50, a polymer with low sintering residual viscoelastic modulus; the organic solvents include terpineol, butyl carbolic acid, butyl carbolic acid acetate, tributyl citrate, and Span 85.

[0106] The silver-aluminum paste on the front side of the above-mentioned N-type TOPCon cell is screen-printed onto a single-crystal N-TOPCon silicon wafer with a size of 182mm×182mm using a 480-mesh screen to form a silver grid. The wafer is then sintered in a sintering furnace at a peak temperature of 770℃.

[0107] After sintering, the electrical properties were tested as follows: open circuit voltage 0.7172V, short circuit current 13.722A, fill factor 83.56%, photoelectric conversion efficiency 24.908%, and EL pin printing ratio 0.02%, which is 2.25% lower than that of conventional front-side silver aluminum paste EL pin printing ratio.

[0108] Comparative Example 1

[0109] (1) Preparation of glass powder:

[0110] Weigh out 22 parts Bi2O3, 7 parts Al2O3, 10 parts SiO2, 20 parts PbO, 18 parts Sb2O5, 5 parts B2O3, 15 parts TiO2, and 3 parts V2O5 by weight, mix them evenly with a mixer, and then sinter and pulverize to obtain glass powder with a D50 of 1.2 to 1.8 μm.

[0111] (2) Preparation of silver-aluminum paste on the front side of N-type TOPCon battery:

[0112] Weigh out 78 parts by weight of micron-sized spherical silver powder with a purity of 99.99% or higher, 3 parts of nano-sized spherical silver powder with a purity of 99.99% or higher, 1.5 parts of micron-sized spherical aluminum powder with a purity of 99.99% or higher, 1 part of nano-sized spherical aluminum powder with a purity of 99.99% or higher, 14.1 parts of organic binder, and 1.5 parts of glass powder. Mix them evenly using a disperser, then grind them to below 10 microns using a three-roll mill. Add 0.6 parts of organic additive to obtain the N-type TOPCon battery front silver-aluminum paste.

[0113] The organic additives include lauryl phosphate and BYKl09;

[0114] The organic binder comprises 8% by weight of a high molecular weight polymer and 92% by weight of an organic solvent;

[0115] The polymer is ethyl cellulose-N50, a polymer with low sintering residual viscoelastic modulus; the organic solvents include terpineol, butyl carbolic acid, butyl carbolic acid acetate, tributyl citrate, and Span 85.

[0116] The silver-aluminum paste on the front side of the above-mentioned N-type TOPCon cell was screen-printed onto a single-crystal N-TOPCon silicon wafer with a size of 182mm×182mm using a 480-mesh screen to form a silver grid. The wafer was then sintered in a sintering furnace at a peak temperature of 772℃.

[0117] After sintering, the electrical properties were tested as follows: open circuit voltage 0.7143V, short circuit current 13.711, fill factor 83.8%, photoelectric conversion efficiency 24.858%, and EL pin imprint ratio 0.05%.

[0118] Experimental data show that, compared with Comparative Example 1, the N-type TOPCon battery front silver-aluminum paste provided in Examples 1 to 4 can effectively improve battery efficiency and reduce EL pin printing ratio while ensuring fill factor.

[0119] In summary, the N-type TOPCon battery front-side silver-aluminum paste provided in this embodiment comprises aluminum powder, silver powder, nano-alloy powder, organic binder, glass powder, and organic additives. The nano-alloy powder is one or more of nano-silver-aluminum alloy powder, nano-aluminum-boron alloy powder, and nano-aluminum-silicon alloy powder. Because nano-silver-aluminum alloy powder, nano-aluminum-boron alloy powder, and nano-aluminum-silicon alloy powder all possess nanoscale particle size, high tap density, low oxygen content, and high activity, the front-side silver-aluminum paste with added nano-alloy powder can quickly form a good alloy with silicon at a relatively low sintering temperature. This reduces the contact resistivity between the front-side silver-aluminum grid and the battery, not only avoiding pin marks during EL testing but also improving battery filling and efficiency.

[0120] 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.

[0121] The foregoing has provided a detailed description of the N-type TOPCon battery front-side silver-aluminum paste, its preparation method, and the battery itself. 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 N-type TOPCon cell front side silver aluminum paste, characterized in that, The components of the silver-aluminum paste include aluminum powder, silver powder, nano-alloy powder, organic binder, glass powder and organic additive, wherein the nano-alloy powder is one or more of nano-silver-aluminum alloy powder, nano-aluminum-boron alloy powder and nano-aluminum-silicon alloy powder; the mass fraction of the silver powder is 78-84%; the mass fraction of the aluminum powder is 1-3%; the mass fractions of the nano-alloy powder, the organic binder, the glass powder and the organic additive are 0.1-0.5%, 9.7-19.6%, 1-2% and 0.3-0.8% respectively; The silver powder includes micron-sphere silver powder and nano-sphere silver powder, and the aluminum powder includes micron-sphere aluminum powder and nano-sphere aluminum powder.

2. The N-type TOPCon cell front side silver-aluminum paste according to claim 1, characterized in that, The organic additive includes one or more of DiGol 655, BYK109, aluminate coupling agent, silane coupling agent, zirconium-aluminate coupling agent, lauryl phosphate, silicone oil and dibasic acid ester mixture.

3. The N-type TOPCon cell front side silver-aluminum paste according to claim 1, characterized in that, The organic binder includes high-molecular polymer and organic solvent; The mass fraction of the high-molecular polymer in the organic binder is 7-11%; The mass fraction of the organic solvent in the organic binder is 89-93%.

4. The N-type TOPCon cell front side silver-aluminum paste according to claim 3, characterized in that, The organic solvent is four or more than four of terpineol, butyl carbityl alcohol, butyl carbityl alcohol acetate, tributyl citrate, Span 85, turpentine oil, triethyl citrate, acetylated tributyl citrate, alcohol ester twelve, lecithin and diethylene glycol ether.

5. The N-type TOPCon cell front side silver-aluminum paste according to claim 1, characterized in that, The D50 of the glass powder is 1.2-1.8 μm.

6. The N-type TOPCon cell front side silver-aluminum paste according to claim 1, characterized in that, The glass powder is obtained by sintering and crushing 22 parts of Bi2O3, 7 parts of Al2O3, 10 parts of SiO2, 20 parts of PbO, 18 parts of Sb2O5, 5 parts of B2O3, 15 parts of TiO2 and 3 parts of V2O5.

7. A method for preparing a front-side silver-aluminum paste for N-type TOPCon cells, characterized in that, The method comprises the following steps: The silver powder, the aluminum powder, the nano-alloy powder, the organic binder and the glass powder are mixed to obtain a mixture, wherein the nano-alloy powder is one or more of nano-silver-aluminum alloy powder, nano-aluminum-boron alloy powder and nano-aluminum-silicon alloy powder; the mass fraction of the silver powder is 78-84%; the mass fraction of the aluminum powder is 1-3%; the mass fractions of the nano-alloy powder, the organic binder, the glass powder and the organic additive are 0.1-0.5%, 9.7-19.6%, 1-2% and 0.3-0.8% respectively; the silver powder includes micron-sphere silver powder and nano-sphere silver powder, and the aluminum powder includes micron-sphere aluminum powder and nano-sphere aluminum powder; After the mixture is ground, the organic additive is added to obtain an N-type TOPCon cell front silver-aluminum paste.

8. An N-type TOPCon cell, characterized in that, The N-type TOPCon has a plurality of grid lines attached to the front surface, and the grid lines are prepared from the silver-aluminum paste according to any one of claims 1-6.

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