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

Abstract

The embodiment of the present application provides an IBC battery aluminum paste, a preparation method thereof and an IBC battery. The IBC battery aluminum paste provided by the embodiment of the present application comprises aluminum powder, boron powder, glass powder, fumed silica, an organic binder and an organic auxiliary agent. By adding fumed silica into the aluminum paste, the fumed silica can be uniformly distributed around the aluminum powder during the process of forming fine grids of the aluminum paste, so as to block the mutual fusion of the aluminum powder and aluminum powder, reduce the difference of stress release coefficient between the aluminum paste and the silicon wafer, and reduce the warping of the IBC battery during the cooling after sintering, thereby solving the problem that the existing IBC battery aluminum paste is prone to causing the warping of the IBC battery and causing the hidden cracking of the battery wafer when being printed into a positive electrode grid line.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crystalline silicon solar cell manufacturing, in particular to an IBC cell aluminum paste, a preparation method thereof and an IBC cell. BACKGROUND

[0002] The IBC (Interdigitated Back Contact) cell is a new type of cell in which the P / N junction, the base and the contact electrode of the emitter region are arranged in an interdigitated shape on the back surface of the cell. The core technology is to prepare p+ and n+ regions with good quality and in an interdigitated and spaced arrangement on the back surface of the cell.

[0003] At present, the IBC cell needs to print aluminum paste on the p+ region and sinter to form the positive electrode grid lines. However, aluminum and silicon are prone to form aluminum-silicon alloy during sintering, which will increase the warpage of the IBC cell when cooled, causing the cell to crack, and further leading to economic losses. SUMMARY

[0004] The technical problem to be solved by the present application is to provide an IBC cell aluminum paste, a preparation method thereof and an IBC cell, so as to solve the problem that the existing IBC cell aluminum paste is prone to cause the IBC cell to warp when printed into positive electrode grid lines, causing the cell to crack.

[0005] To solve the above problems, the present application is realized by the following technical scheme:

[0006] The present application provides an IBC cell aluminum paste, wherein the components of the aluminum paste include aluminum powder, boron powder, glass powder, fumed silica, organic binder and organic additive.

[0007] Further, in the IBC cell aluminum paste, the mass percentage of the aluminum powder is 72-77%; the mass percentage of the boron powder is 0.04-0.1%; the mass percentage of the glass powder is 1-1.5%; the mass percentage of the fumed silica is 0.03-0.06%; the mass percentage of the organic binder is 20.74-25.74%; and the mass percentage of the organic additive is 0.2-0.6%.

[0008] Further, in the IBC cell aluminum paste, the fumed silica includes nanoscale fumed silica.

[0009] Further, in the IBC cell aluminum paste, the organic additive includes one or more of fatty alcohol ether phosphate, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, lauryl alcohol phosphate, DiGao 655 and BYK 110.

[0010] Further, in the IBC battery aluminum paste, the aluminum powder comprises micro-sphere aluminum powder and nano-sphere aluminum powder.

[0011] Further, in the IBC battery aluminum paste, the organic binder comprises high-molecular polymer resin and organic solvent.

[0012] The mass fraction of the high-molecular polymer in the organic binder is 6-8%.

[0013] The mass fraction of the organic solvent in the organic binder is 92-94%.

[0014] Further, in the IBC battery aluminum paste, the organic solvent comprises at least four of benzyl alcohol, diethyl phthalate, terpineol, butyl carbityl alcohol, butyl carbityl alcohol acetate, tributyl citrate, Span 85 and alcohol ester twelve.

[0015] Further, in the IBC battery aluminum paste, the glass powder is obtained by sintering and crushing 3-15 parts of SiO2, 1-15 parts of Bi2O3, 35-80 parts of PbO, 0.5-5 parts of TiO2, 0.5-5 parts of Al2O3, 0.5-10 parts of ZnO, 0.5-3 parts of MgO, 0.5-5 parts of V2O5 and 0.5-3 parts of Li2O.

[0016] The application further provides a preparation method of the IBC battery aluminum paste.

[0017] The organic binder, boron powder, aluminum powder, fumed silica and glass powder are mixed to obtain a mixture.

[0018] After the mixture is ground, the organic auxiliary agent is added to obtain the IBC battery aluminum paste.

[0019] The application further provides an IBC battery, wherein the back surface of the IBC battery is attached with a plurality of positive electrode grid lines, and the grid lines are prepared from the above-mentioned aluminum paste.

[0020] Compared with the prior art, the application has the following advantages:

[0021] In the application, the IBC battery aluminum paste comprises aluminum powder, boron powder, glass powder, fumed silica, organic binder and organic auxiliary agent. By adding fumed silica into the aluminum paste, the fumed silica can be uniformly distributed around the aluminum powder during the process of forming fine grid of the aluminum paste, so that the mutual fusion of the aluminum powder is blocked, the difference of stress release coefficient between the aluminum paste and the silicon wafer is reduced, and the warping of the IBC battery during the cooling after sintering is reduced, thereby solving the problem that the IBC battery is prone to warping and causes the battery wafer to crack when the IBC battery aluminum paste is printed into positive electrode grid lines.

[0022] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a preparation method flow chart of the IBC battery silver aluminum paste provided by the embodiment of the application. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the application will be further described in detail below in combination with the drawings and specific embodiments.

[0025] The applicant of the application finds that in the current positive metallization process of P-type IBC, aluminum paste needs to be printed in the laser groove in conduction with the P-type doped region, and then the positive grid line is formed by high-temperature sintering. However, aluminum and silicon can easily form aluminum-silicon alloy under high-temperature conditions exceeding 577 degrees Celsius, and the grid line of the IBC battery is printed on the back of the battery, which makes the above-mentioned aluminum-silicon alloy have a difference in stress release coefficient with the silicon wafer during cooling, and can significantly increase the warpage of the IBC battery, cause the battery wafer to crack, and further cause economic loss.

[0026] Especially, with the influence of factors such as the rise in the price of silicon materials, the thickness of the silicon wafer has been reduced from 170 microns to 140 microns, which further aggravates the warpage of the IBC battery caused by the formation of aluminum-silicon alloy in the metallization process.

[0027] In order to solve the above-mentioned problems, the embodiment of the application provides an IBC battery aluminum paste, and the components constituting the aluminum paste include aluminum powder, boron powder, glass powder, fumed silica, an organic binder and an organic auxiliary agent.

[0028] The IBC battery aluminum paste provided by the embodiment of the application can be an aluminum paste for forming a positive grid line of a P-type IBC battery, or an aluminum paste for forming a positive grid line of an N-type IBC battery, and specifically is printed in a laser groove in conduction with a P-type doped region on the back of the IBC battery, and then high-temperature sintering is performed, so that the positive grid line can be formed.

[0029] The aluminum powder is the main component, and the aluminum powder mainly replaces the P+ emitter of the battery; the glass powder is an inorganic binder, which will melt into a liquid state under high temperature conditions, and will condense when cooled, thereby playing a bonding role; the organic binder can ensure the overall bonding effect; the organic auxiliary agent can reduce the overall viscosity of the aluminum paste; and the boron powder can diffuse into the silicon during high-temperature sintering to perform heavy doping, which is beneficial to improving the contact performance of the paste and reducing the reaction contact surface between aluminum and silicon; and in the process of forming a fine grid of the aluminum paste, the fumed silica can be uniformly distributed around the aluminum powder, block the mutual fusion of the aluminum powder, reduce the stress release coefficient difference between the aluminum paste and the silicon wafer, reduce the warping of the IBC battery after sintering and cooling, and relieve the hidden cracks of the battery caused by warping.

[0030] Therefore, the aluminum paste provided by the embodiment of the present application can effectively solve the problem that the existing IBC battery aluminum paste is prone to causing warping of the IBC battery and hidden cracks of the battery when printed into a positive grid line.

[0031] Optionally, in an embodiment, the mass percentage of the aluminum powder in the aluminum paste is 72-77%; the mass percentage of the boron powder is 0.04-0.1%; the mass percentage of the glass powder is 1-1.5%; the mass percentage of the fumed silica is 0.03-0.06%; the mass percentage of the organic binder is 20.74-25.74%; and the mass percentage of the organic auxiliary agent is 0.2-0.6%. The content of the fumed silica in the aluminum paste provided by the embodiment of the present application is low, so that the electrical performance of the battery wafer remains good.

[0032] For example, the mass fractions of the aluminum powder, the boron powder, the glass powder, the fumed silica, the organic binder and the organic auxiliary agent in the aluminum paste are 72%, 0.1%, 1.5%, 0.06%, 25.74% and 0.6%, respectively.

[0033] For example, the mass fractions of the aluminum powder, the boron powder, the glass powder, the fumed silica, the organic binder and the organic auxiliary agent in the aluminum paste are 77%, 0.04%, 1%, 0.03%, 21.73% and 0.2%, respectively.

[0034] For example, the mass fractions of the aluminum powder, the boron powder, the glass powder, the fumed silica, the organic binder and the organic auxiliary agent in the aluminum paste are 77%, 0.1%, 1.5%, 0.06%, 20.74% and 0.6%, respectively.

[0035] For example, the mass fractions of the aluminum powder, the boron powder, the glass powder, the fumed silica, the organic binder and the organic auxiliary agent in the aluminum paste are 75%, 0.03%, 1.3%, 0.04%, 23.28% and 0.35%, respectively.

[0036] For example, the mass fractions of the aluminum powder, boron powder, glass powder, fumed silica, organic binder and organic auxiliary in the aluminum paste are 77%, 0.08%, 1.5%, 0.06%, 20.86% and 0.5% respectively.

[0037] Optionally, in an embodiment, the fumed silica includes nanoscale fumed silica.

[0038] Optionally, in an embodiment, the boron powder includes micrometer-scale elemental boron. By adding the micrometer-scale elemental boron, the boron powder can quickly diffuse into the silicon at high-temperature sintering to perform heavy doping, which is beneficial to improving the contact performance of the paste.

[0039] Optionally, in an embodiment, the aluminum powder includes micrometer-scale spherical aluminum powder and nanoscale spherical aluminum powder. The nanoscale spherical aluminum powder can just fill and penetrate into the gaps between the micrometer-scale aluminum powder.

[0040] Optionally, in a specific embodiment, the aluminum powder includes micrometer-scale spherical aluminum powder with a mass fraction of 90-95% and nanoscale spherical aluminum powder with a mass fraction of 5-10%. The nanoscale spherical aluminum powder can just fill and penetrate into the gaps between the micrometer-scale aluminum powder.

[0041] Optionally, in a specific embodiment, the aluminum powder includes micrometer-scale spherical aluminum powder with a mass fraction of 90-95% and nanoscale spherical aluminum powder with a mass fraction of 5-10%. The nanoscale spherical aluminum powder can just fill and penetrate into the gaps between the micrometer-scale aluminum powder.

[0042] Optionally, in an embodiment, the organic auxiliary includes one or more of fatty alcohol ether phosphate, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, lauryl alcohol phosphate, Digol 655 and BYK 110.

[0043] In the IBC battery aluminum paste provided in the embodiments of the present application, the organic binder includes a high-molecular polymer resin and an organic solvent. The high-molecular polymer resin is dissolved in the organic solvent, so that the organic solvent can act as an organic binder, i.e., the paste can play a role of binding the powder after being dried.

[0044] Optionally, in an embodiment, the mass fraction of the high-molecular polymer in the organic binder is 6-8%, and the mass fraction of the organic solvent in the organic binder is 92-94%.

[0045] Optionally, in an embodiment, the high-molecular polymer is one or more of ethyl cellulose-N20, ethyl cellulose N-50 and ethyl cellulose-N100.

[0046] The organic solvent includes at least four of benzyl alcohol, diethyl phthalate, terpineol, butyl carbitol, butyl carbitol acetate, tributyl citrate, Span 85 and alcohol ester twelve.

[0047] Optionally, in an embodiment, the glass powder is obtained by sintering and crushing 3-15 parts by mass of SiO2, 1-15 parts of Bi2O3, 35-80 parts of PbO, 0.5-5 parts of TiO2, 0.5-5 parts of Al2O3, 0.5-10 parts of ZnO, 0.5-3 parts of MgO, 0.5-5 parts of V2O5, and 0.5-3 parts of Li2O, wherein the D50 of the glass powder is 1.0-1.8 μm; if the D50 is less than 1.0 μm, the glass activity is too large; and if the D50 is greater than 1.8 μm, the glass activity is too small.

[0048] In the formula, SiO2 is used as a glass network former to promote glass stability and increase the glass melting point; Bi2O3 is used as a main network structure; PbO is used to adjust the glass corrosion and reduce the glass melting point; TiO2 is used for local crystallization; Al2O3 is used to adjust the glass stability and increase the viscosity; ZnO is used to break the network structure and promote glass crystallization; MgO and V2O5 are used to reduce the melting point; and Li2O is used to adjust the glass stability, increase the viscosity, and promote crystallization.

[0049] The embodiment of the present application further provides a preparation method of the IBC battery aluminum paste, wherein, as shown in the figure, Figure 1 the preparation method comprises steps 101-102:

[0050] In step 101, the organic binder, boron powder, aluminum powder, fumed silica and glass powder are mixed to obtain a mixture.

[0051] In step 102, the mixture is ground, and then the organic additive is added to obtain the IBC battery aluminum paste.

[0052] In step 101, 20.74-25.74 parts by mass of the organic binder, 0.04-0.1 parts of the boron powder, 72-77 parts of the aluminum powder, 0.03-0.06 parts of the fumed silica and 1-1.5 parts of the glass powder are weighed and mixed, and then a disperser is used for dispersion to obtain the mixture.

[0053] Optionally, in an embodiment, the aluminum powder includes micron-sphere aluminum powder and nano-sphere aluminum powder; in step 101, the organic binder, the nano-sphere aluminum powder and the fumed silica are mixed, and then a disperser is used for dispersion; then the boron powder, the micron-sphere aluminum powder and the glass powder are added, and a disperser is used for dispersion again; and then the mixture is ground to obtain the mixture.

[0054] In step 102, 0.2-0.6 parts of organic additives are added to the mixture after grinding, and the high-efficiency IBC battery aluminum paste with low warping is obtained after high-speed dispersion.

[0055] In the embodiment, the fumed silica is added to the aluminum paste, and the fumed silica is uniformly distributed around the aluminum powder during the formation of the fine grid, so as to prevent the mutual fusion of the aluminum powder, reduce the difference between the stress release coefficients of the aluminum paste and the silicon wafer, and reduce the warping of the IBC battery during the cooling after sintering, thereby solving the problem that the IBC battery is prone to warping and cracking during the printing of the positive grid lines.

[0056] Optionally, in the preparation method, the fumed silica includes nanoscale fumed silica.

[0057] Optionally, in the preparation method, the organic additives include one or more of fatty alcohol ether phosphate, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, lauryl alcohol phosphate, DiGol 655, and BYK 110.

[0058] Optionally, in the preparation method, the organic binder includes a high-molecular polymer resin and an organic solvent.

[0059] The mass fraction of the high-molecular polymer in the organic binder is 6-8%.

[0060] The mass fraction of the organic solvent in the organic binder is 92-94%.

[0061] Optionally, in the preparation method, the organic solvent includes at least four of benzyl alcohol, diethyl phthalate, terpineol, butyl carbityl alcohol, butyl carbityl alcohol acetate, tributyl citrate, Span 85, and alcohol ester twelve.

[0062] Optionally, in the preparation method, the glass powder is obtained by sintering and crushing 3-15 parts of SiO2, 1-15 parts of Bi2O3, 35-80 parts of PbO, 0.5-5 parts of TiO2, 0.5-5 parts of Al2O3, 0.5-10 parts of ZnO, 0.5-3 parts of MgO, 0.5-5 parts of V2O5, and 0.5-3 parts of Li2O.

[0063] The application further provides an IBC battery, wherein the back surface of the IBC battery is attached with a plurality of positive grid lines, and the grid lines are prepared from the aluminum paste.

[0064] The steps of manufacturing the P-type IBC cell by using the aluminum paste provided by the embodiment of the application are as follows:

[0065] (1) After forming the ultra-thin silicon oxide layer and the polysilicon layer on the back surface of the P-type silicon wafer, the polysilicon layer on the back surface is doped with phosphorus;

[0066] (2) The laser slotting is performed to form the n+ doped region and the p+ doped region arranged in the interdigital form; then the ALD (Atomic Layer Deposition) process is performed to form the aluminum oxide film, and the silicon nitride film is formed on the front and back surfaces, so as to form the passivation layer;

[0067] (3) The laser slotting is performed on the back surface of the cell to form the laser slot in communication with the p+ doped region;

[0068] (4) The above-mentioned aluminum paste is printed in the laser slot, and the silver paste is printed on the passivation layer opposite to the n+ doped region;

[0069] (5) The silicon wafer after printing is subjected to high-temperature sintering at the maximum temperature of 788 degrees Celsius, so as to obtain the P-type IBC cell.

[0070] The application will be described in detail through the embodiments.

[0071] Embodiment 1

[0072] (1) The silver aluminum paste a1 is provided: the IBC cell aluminum paste a1 is composed of 75 parts of aluminum powder, 0.03 parts of boron powder, 1.3 parts of glass powder, 0.04 parts of fumed silica, 23.28 parts of organic binder and 0.35 parts of organic auxiliary agent by mass fraction;

[0073] The organic auxiliary agent is lauryl alcohol phosphoric acid ester; the aluminum powder includes micron spherical aluminum powder with a purity of 3n9 and a mass fraction of 92%, and nanometer spherical aluminum powder with a purity of 3n9 and a mass fraction of 8%; the organic binder includes ethyl cellulose-N100 with a mass fraction of 7% and organic solvent with a mass fraction of 93%, and the organic solvent includes butyl carbitol, butyl carbitol acetate, tributyl citrate, Span 85 and alcohol ester.

[0074] (2) After forming the silicon oxide layer and the polysilicon layer on the back surface of the P-type silicon wafer in sequence, the polysilicon layer on the back surface is doped with phosphorus;

[0075] (3) The laser slotting is performed on the back surface of the P-type silicon wafer after phosphorus doping to form the n+ doped region and the p+ doped region arranged in the interdigital form, and the polysilicon layer on the front surface is removed;

[0076] (4) After removing the front side polysilicon layer and sequentially forming the double-sided aluminum oxide layer, the front side silicon nitride layer, and the back side silicon nitride layer, the positive electrode grid line is formed by printing the aluminum paste a1 in the laser groove in communication with the p+ doped region through a 360-mesh screen printing, and the negative electrode grid line is printed on the back side silicon nitride layer opposite to the n+ doped region;

[0077] (5) The silicon wafer is subjected to high-temperature sintering in a sintering furnace, and the peak temperature of sintering is 788°C to obtain the IBC battery.

[0078] After sintering, the electrical data is tested to be: open-circuit voltage 0.722V, short-circuit current 13.915A, fill factor 82.55%, photoelectric conversion efficiency 25.12%, and warpage 0.3mm lower than that of the conventional aluminum paste.

[0079] Example 2

[0080] (1) Silver aluminum paste a2 is provided: by mass parts, the IBC battery aluminum paste a2 is composed of 77 parts of aluminum powder, 0.08 parts of boron powder, 1.5 parts of glass powder, 0.06 parts of fumed silica, 20.86 parts of organic binder, and 0.5 parts of organic additive;

[0081] The organic additive is lauryl alcohol phosphatide; the aluminum powder includes micron spherical aluminum powder with a purity of 3n9 and a mass fraction of 93%, and nanometer spherical aluminum powder with a purity of 3n9 and a mass fraction of 7%; the organic binder includes ethyl cellulose-N100 with a mass fraction of 8% and organic solvent with a mass fraction of 92%, and the organic solvent includes butyl carbitol, butyl carbitol acetate, tributyl citrate, Span 85, and alcohol ester twelve.

[0082] (2) After forming the silicon oxide layer and the polysilicon layer on the back side of the P-type silicon wafer, the back side polysilicon layer is doped with phosphorus;

[0083] (3) After laser grooving on the back side of the P-type silicon wafer after phosphorus doping, the n+ doped region and the p+ doped region are formed in an interdigital and spaced arrangement, and the front side polysilicon layer is removed;

[0084] (4) After removing the front side polysilicon layer and sequentially forming the double-sided aluminum oxide layer, the front side silicon nitride layer, and the back side silicon nitride layer, the positive electrode grid line is formed by printing the aluminum paste a2 in the laser groove in communication with the p+ doped region through a 360-mesh screen printing, and the negative electrode grid line is printed on the back side silicon nitride layer opposite to the n+ doped region;

[0085] (5) The silicon wafer is subjected to high-temperature sintering in a sintering furnace, and the peak temperature of sintering is 782°C to obtain the IBC battery.

[0086] The electrical data of the sintered product is as follows: open circuit voltage 0.721 V, short circuit current 13.905 A, fill factor 82.45%, photoelectric conversion efficiency 25.037%, and warpage 0.4 mm lower than that of the conventional aluminum paste.

[0087] Example 3

[0088] (1) providing silver aluminum paste a3: by mass fraction, IBC battery aluminum paste a3 is composed of 72 parts of aluminum powder, 0.1 parts of boron powder, 1.5 parts of glass powder, 0.06 parts of fumed silica, 25.74 parts of organic binder and 0.6 parts of organic auxiliary agent;

[0089] Wherein, the organic auxiliary agent is lauryl alcohol phosphatide; the aluminum powder includes micron spherical aluminum powder with a purity of 3 9 and a mass fraction of 92%, and nanometer spherical aluminum powder with a purity of 3 9 and a mass fraction of 8%; the organic binder includes ethyl cellulose-N100 with a mass fraction of 7% and organic solvent with a mass fraction of 93%, and the organic solvent includes butyl carbol, butyl carbol acetate, tributyl citrate, Span 85 and alcohol ester twelve.

[0090] (2) after forming a silicon oxide layer and a polysilicon layer on the back of the P-type silicon wafer in sequence, the polysilicon layer on the back is doped with phosphorus;

[0091] (3) laser grooving is performed on the back of the P-type silicon wafer after phosphorus doping to form interdigital n+ doped regions and p+ doped regions arranged at intervals, and the front polysilicon layer is removed;

[0092] (4) after removing the front polysilicon layer and forming a double-sided aluminum oxide layer, a front silicon nitride layer and a back silicon nitride layer in sequence, the aluminum paste a3 is printed on the laser groove in contact with the p+ doped region through a 360-mesh silk screen to form a positive grid line, and a silver paste negative grid line is printed on the back silicon nitride layer opposite to the n+ doped region;

[0093] (5) the silicon wafer is sintered at high temperature in a sintering furnace, and the peak temperature of sintering is 782℃, to obtain an IBC battery.

[0094] The electrical data of the sintered product is as follows: open circuit voltage 0.719, short circuit current 13.854 A, fill factor 83.45%, photoelectric conversion efficiency 25.161%, and warpage 0.48 mm lower than that of the conventional aluminum paste.

[0095] Example 4

[0096] (1) providing silver aluminum paste a4: by mass fraction, IBC battery aluminum paste a4 is composed of 77 parts of aluminum powder, 0.04 parts of boron powder, 1 parts of glass powder, 0.03 parts of fumed silica, 21.73 parts of organic binder and 0.2 parts of organic auxiliary agent;

[0097] The organic adjuvant is lauryl alcohol phosphoric acid ester; the aluminum powder includes micron spherical aluminum powder with a purity of 3@9 and a mass fraction of 92%, and nanometer spherical aluminum powder with a purity of 3@9 and a mass fraction of 8%; the organic binder includes ethyl cellulose-N100 with a mass fraction of 7% and an organic solvent with a mass fraction of 93%, and the organic solvent includes butyl carbitol, butyl carbitol acetate, tributyl citrate, Span 85, and alcohol ester twelve.

[0098] (2) After forming a silicon oxide layer and a polysilicon layer on the back surface of the P-type silicon wafer in sequence, the polysilicon layer on the back surface is doped with phosphorus;

[0099] (3) After the P-type silicon wafer is doped with phosphorus, laser grooving is performed on the back surface to form interdigitated n+ doped regions and p+ doped regions arranged at intervals, and the polysilicon layer on the front surface is removed;

[0100] (4) After the polysilicon layer on the front surface is removed and a double-sided aluminum oxide layer, a front surface silicon nitride layer, and a back surface silicon nitride layer are formed in sequence, the front surface silicon nitride layer is printed with a silver paste to form a positive electrode grid line in the laser groove that is in conduction with the p+ doped region, and the back surface silicon nitride layer opposite to the n+ doped region is printed with an aluminum paste to form a negative electrode grid line;

[0101] (5) The silicon wafer is subjected to high-temperature sintering in a sintering furnace, and the peak temperature of the sintering is 782℃, thereby obtaining an IBC battery.

[0102] After sintering, the electrical property data of the IBC battery is as follows: an open-circuit voltage of 0.720V, a short-circuit current of 13.845A, a fill factor of 83.451%, and a photoelectric conversion efficiency of 25.197%, and the warpage is 0.45mm lower than that of a conventional aluminum paste.

[0103] Comparative Example 1

[0104] (1) A silver aluminum paste b1 is provided: the IBC battery aluminum paste b1 is composed of 77.06 parts by mass of aluminum powder, 0.08 parts by mass of boron powder, 1.5 parts by mass of glass powder, 20.86 parts by mass of an organic binder, and 0.5 parts by mass of an organic adjuvant;

[0105] The organic adjuvant is lauryl alcohol phosphoric acid ester; the aluminum powder includes micron spherical aluminum powder with a purity of 3@9 and a mass fraction of 92%, and nanometer spherical aluminum powder with a purity of 3@9 and a mass fraction of 8%; the organic binder includes ethyl cellulose-N100 with a mass fraction of 7% and an organic solvent with a mass fraction of 93%, and the organic solvent includes butyl carbitol, butyl carbitol acetate, tributyl citrate, Span 85, and alcohol ester twelve.

[0106] (2) After forming a silicon oxide layer and a polysilicon layer on the back surface of the P-type silicon wafer in sequence, the polysilicon layer on the back surface is doped with phosphorus;

[0107] (3) laser grooving on the back surface of the P-type silicon wafer after phosphorus doping, forming the n+ doped region and p+ doped region in the form of interdigital spacing, and removing the front surface polysilicon layer;

[0108] (4) after removing the front surface polysilicon layer and sequentially forming the double-sided aluminum oxide layer, the front surface silicon nitride layer and the back surface silicon nitride layer, forming the positive electrode grid line by printing the above-mentioned aluminum paste b1 in the laser groove in contact with the p+ doped region through 360 mesh silk screen printing, and printing the silver paste negative electrode grid line on the back surface silicon nitride layer opposite to the n+ doped region;

[0109] (5) high-temperature sintering of the silicon wafer in a sintering furnace, with a sintering peak temperature of 782℃, to obtain the IBC battery.

[0110] After sintering, the electrical data of the battery is as follows: open-circuit voltage 0.7195V, short-circuit current 13.855A, fill factor 83.31%, photoelectric conversion efficiency 25.154%, and warpage 0.65mm.

[0111] Comparing Examples 1-4 with Comparative Example 1, it can be seen that the use of aluminum paste doped with fumed silica to form the P+ emitter can reduce the warpage of the IBC battery by more than 0.45mm while maintaining the efficiency of the battery.

[0112] In summary, in the present embodiment, by adding fumed silica to the aluminum paste, the fumed silica can be uniformly distributed around the aluminum powder during the formation of the fine grid in the aluminum paste, preventing the mutual fusion of aluminum powder and the combination of aluminum powder under cooling conditions, thereby reducing the warpage of the IBC battery after sintering, and thus solving the problem of IBC battery warpage caused by the printing of the aluminum paste into the positive electrode grid line.

[0113] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to these embodiments once they understand the basic inventive concept. Therefore, the claims are intended to include the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present application.

[0114] The IBC battery aluminum paste, its preparation method and IBC battery provided by the present application have been described in detail above, and specific examples have been applied to explain the principles and implementation methods of the present application. The above description of the embodiments is only intended to help understand the method and core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation and application range; in summary, the content of the present description should not be understood as a limitation of the present application.

Claims

1. An aluminum paste for IBC batteries, characterized in that, The aluminum paste comprises aluminum powder, boron powder, glass powder, fumed silica, organic binder, and organic additives; the glass powder accounts for 1-1.5% by mass; and the fumed silica accounts for 0.03-0.06% by mass. The glass powder, by weight, is obtained by sintering and pulverizing 3-15 parts SiO2, 1-15 parts Bi2O3, 35-80 parts PbO, 0.5-5 parts TiO2, 0.5-5 parts Al2O3, 0.5-10 parts ZnO, 0.5-3 parts MgO, 0.5-5 parts V2O5, and 0.5-3 parts Li2O. In the aluminum paste, the mass percentage of aluminum powder is 72-77%; the mass percentage of boron powder is 0.04-0.1%; the mass percentage of organic binder is 20.74-25.74%; and the mass percentage of organic additives is 0.2-0.6%.

2. The IBC battery aluminum paste according to claim 1, characterized in that, The fumed silica includes nano-sized fumed silica.

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, lauryl phosphate, Digo 655, and BYKl10.

4. 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.

5. 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 binder has a mass fraction of 6-8%; The organic solvent has a mass fraction of 92-94% in the organic binder.

6. The IBC battery aluminum paste according to claim 1, characterized in that, The organic solvents include at least four of the following: benzyl alcohol, diethyl phthalate, terpineol, butyl carbiol, butyl carbiol acetate, tributyl citrate, Span 85, and ester twelve.

7. A method for preparing aluminum paste for IBC batteries, characterized in that, include: An organic binder, boron powder, aluminum powder, fumed silica, and glass powder are mixed to obtain a mixture; the glass powder has a mass percentage of 1-1.5%; the fumed silica has a mass percentage of 0.03-0.06%; the glass powder, by mass, is obtained by sintering and pulverizing 3-15 parts SiO2, 1-15 parts Bi2O3, 35-80 parts PbO, 0.5-5 parts TiO2, 0.5-5 parts Al2O3, 0.5-10 parts ZnO, 0.5-3 parts MgO, 0.5-5 parts V2O5, and 0.5-3 parts Li2O. After grinding the mixture, an organic additive is added to obtain an IBC battery aluminum paste; in the aluminum paste, the mass percentage of aluminum powder is 72~77%; the mass percentage of boron powder is 0.04~0.1%; the mass percentage of organic binder is 20.74~25.74%; and the mass percentage of organic additive is 0.2~0.6%.

8. An IBC battery, characterized in that, The back of the IBC battery has multiple positive grid lines attached, which are prepared from aluminum paste as described in any one of claims 1 to 6.

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