Solar cell conductive paste and photovoltaic module

Abstract

The invention provides solar cell conductive paste and a photovoltaic module. The solar cell conductive paste comprises main glass powder and auxiliary glass powder. Wherein the main glass powder is Pb-Si-B series glass, the auxiliary glass powder is Pb-Ti-Si-B series glass, the mass fraction of the main glass powder in the slurry is 1.5%-2.5%, and the mass fraction of the auxiliary glass powder in the slurry is 0.2%-1%. The paste further comprises silver powder and an organic carrier, the mass fraction of the silver powder is 82%-90%, and the mass fraction of the organic carrier is 8%-15%. The low solubility of the electrode grid line in acetic acid is adjusted through the auxiliary glass, acetic acid corrosion is resisted, the electrode grid line is resistant to high temperature and high humidity, the reliability of the module is improved, and the problem that the efficiency of the battery is affected by acetic acid generated by EVA decomposition of a double-sided EVA module packaging battery is solved. The invention also provides a photovoltaic module using the slurry.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular to a solar cell conductive paste and a photovoltaic module. Background Art

[0002] EVA is a transparent colloid with good flexibility and bonding properties, good light transmission and aging resistance. It encapsulates the crystalline silicon wafer group "upper cover and lower pad", and is bonded to the upper protective material glass and the lower protective material TPT by vacuum lamination technology to form a crystalline silicon module. Single-glass photovoltaic modules absorb solar energy from one side of the module; while double-glass photovoltaic modules absorb solar energy from both sides, and are composed of two pieces of tempered glass, POE or EVA films, and solar cells.

[0003] The official name of EVA resin is ethylene-vinyl acetate copolymer. The vinyl acetate content in EVA used in photovoltaic modules is usually 28-33%. As a common chemical bond, ester has a basic property that it will decompose into acid and alcohol in the presence of water. The acetic acid that slowly accumulates in photovoltaic modules has become an important cause of quality problems in most photovoltaic modules. Because acetic acid can gradually corrode and narrow the silver grid lines on the surface of the cell, and as the silver grid lines become narrower, the power generation efficiency of the module gradually decreases. Therefore, the acetic acid decomposed during the module encapsulation leads to reduced battery performance, interacts with the electrode, causes the metallization site and the cell interface to degrade, the contact resistance increases, and the EL imaging is a dark area, which seriously affects the battery efficiency.

[0004] In order to solve the problem that acetic acid produced by the decomposition of EVA affects the efficiency of double-sided EVA component encapsulated batteries, the present application provides a solar cell conductive paste and a photovoltaic component. Summary of the invention

[0005] In order to solve the problem that acetic acid produced by decomposition of EVA affects the efficiency of double-sided EVA component encapsulated batteries, the present application provides a conductive paste for solar cells, the paste comprising main glass powder and auxiliary glass powder, the mass fraction of the main glass powder in the paste is 1.5% to 2.5%, the mass fraction of the auxiliary glass powder is 0.2% to 1%, the auxiliary glass powder is Pb-Ti-Si-B glass, and based on the total molar percentage content of the auxiliary glass powder as 100 mol%, the auxiliary glass powder comprises PbO 15 mol% to 45 mol%, TiO2 5 mol% to 20 mol%, SiO2 and GeO2 totaling 15 mol% to 50 mol%, B2O3 18 mol% to 30 mol%, Al2O3 0 mol% to 20 mol%, RO 0 mol% to 12 mol%, and a modified additive 1 mol% to 20 mol%, wherein R is one or more of the alkali metals Li, Na or K.

[0006] Acetic acid, a decomposition product of ethylene vinyl acetate (EVA), a common module encapsulation material, interacts with metallization, often causing degradation of the interface between the front metal contact and the underlying silicon (Si) substrate. This leads to loss of cell performance and contact adhesion, increased contact resistance, and dark areas seen in electroluminescence (EL) imaging, so it is imperative to develop new metallization pastes that are more resistant to acetic acid.

[0007] The introduction of Ti can improve the acetic acid performance of glass. The present application adjusts the low solubility of the electrode grid in acetic acid through the secondary glass (Pb-Ti-Si-B glass), improves the good chemical stability of the electrode, and resists acetic acid corrosion.

[0008] Optionally, the elements in the modifying additive include one or more of W, Ca, Mg, Zn, Bi and Ba.

[0009] Optionally, the main glass powder is Pb-Si-B glass. Taking the total molar percentage content of the main glass powder as 100 mol%, the main glass powder includes SiO2 15 mol% to 40 mol%, B2O3 18 mol% to 40 mol%, Al2O3 0 mol% to 20 mol%, PbO and BaO totaling 15 mol% to 45 mol%, RO 0 mol% to 12 mol%, and modifying additives 1 mol% to 20 mol%, wherein R is one or more of the alkali metals Li, Na or K.

[0010] Optionally, the elements in the modifying additive include one or more of Ca, Mg, Se, Ag, Zn, P, Ga and Fe.

[0011] Optionally, the slurry further comprises silver powder and an organic carrier. In the slurry, the mass fraction of the silver powder is 82% to 90%, and the mass fraction of the organic carrier is 8% to 15%.

[0012] Optionally, the organic carrier comprises an organic solvent, an organic resin and an additive, wherein the mass fraction of the organic solvent in the organic carrier is 60% to 93%, the mass fraction of the organic resin is 5% to 20%, and the mass fraction of the additive is 2% to 20%.

[0013] Optionally, the glass powder includes a main glass powder and a secondary glass powder, and the preparation method of the glass powder includes:

[0014] The raw materials of various components are uniformly mixed, heated until melted, and cooled to obtain glass frit;

[0015] The glass material is ground and sieved to obtain glass powder.

[0016] Optionally, the preparation method specifically comprises:

[0017] The raw materials of various components are uniformly mixed, put into a platinum crucible, melted at 900-1300°C for 30-90 minutes, and then cooled to obtain glass material;

[0018] The glass material is ground and screened to obtain glass powder, and the glass powder has a D100 of less than or equal to 6 um.

[0019] Optionally, the slurry is applied to an N-type solar cell processed by a laser enhanced contact optimization process.

[0020] The present application also provides a photovoltaic module, which includes a first cover plate, a first adhesive film, a battery string, a second adhesive film and a second cover plate which are stacked, wherein the first adhesive film and the second adhesive film are EVA; the battery string includes a plurality of electrically connected solar cells, and the electrodes of the solar cells are formed by applying any of the solar cell conductive pastes described above.

[0021] The present application provides a solar cell conductive paste, the paste comprising a main glass powder and a secondary glass powder. The main glass powder is Pb-Si-B glass, the secondary glass powder is Pb-Ti-Si-B glass, the mass fraction of the main glass powder in the paste is 1.5% to 2.5%, and the mass fraction of the secondary glass powder is 0.2% to 1%. The paste also includes silver powder and an organic carrier, the mass fraction of the silver powder is 82% to 90%, and the mass fraction of the organic carrier is 8% to 15%. The present application adjusts the low solubility of the electrode grid in acetic acid through the secondary glass, improves the good chemical stability of the electrode, resists acetic acid corrosion, makes the electrode grid resistant to high temperature and high humidity, improves the reliability of the component, and solves the problem that the acetic acid produced by the decomposition of EVA affects the battery efficiency of the double-sided EVA component encapsulated battery. The present application also provides a photovoltaic component using the above-mentioned paste. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0023] Figure 1 This is a schematic diagram of the electrode cross section of the B1 battery cell before the acetic acid atmosphere;

[0024] Figure 2 This is a schematic diagram of the electrode cross section of the B1 battery cell in acetic acid atmosphere;

[0025] Figure 3 This is a schematic diagram of the electrode cross section of the K2 battery cell before the acetic acid atmosphere;

[0026] Figure 4 This is a schematic diagram of the electrode cross-section of the K2 battery cell in acetic acid atmosphere. DETAILED DESCRIPTION

[0027] The following embodiments are described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following embodiments do not represent all implementations consistent with the present application. They are only examples of systems and methods consistent with some aspects of the present application as detailed in the claims.

[0028] In order to solve the problem that acetic acid produced by decomposition of EVA affects the efficiency of double-sided EVA component encapsulated batteries, the present application provides a conductive paste for solar cells, the paste comprising main glass powder and auxiliary glass powder, the mass fraction of the main glass powder in the paste is 1.5% to 2.5%, the mass fraction of the auxiliary glass powder is 0.2% to 1%, the auxiliary glass powder is Pb-Ti-Si-B glass, and based on the total molar percentage content of the auxiliary glass powder as 100 mol%, the auxiliary glass powder comprises PbO 15 mol% to 45 mol%, TiO2 5 mol% to 20 mol%, SiO2 and GeO2 totaling 15 mol% to 50 mol%, B2O3 18 mol% to 30 mol%, Al2O3 0 mol% to 20 mol%, RO 0 mol% to 12 mol%, and a modified additive 1 mol% to 20 mol%, wherein R is one or more of the alkali metals Li, Na or K.

[0029] EVA acts as an air and electrical insulator in the component, protecting it from mechanical damage and preventing corrosion from the external environment. However, under the action of photosynthetic heat, acetic acid is a decomposition product of the module packaging material ethylene-vinyl acetate (EVA). Acetic acid solution basically does not corrode pure aluminum at room temperature, but as the temperature rises, the corrosion rate accelerates. The corrosion rate of 1% dilute acetic acid solution on aluminum at boiling temperature is 100 times that of room temperature; the corrosion rate of acetic acid on aluminum is also related to the purity of aluminum. Low-purity aluminum, such as aluminum containing impurities such as iron, silicon, and aluminum salts on the surface, forms a loose and dense oxide protective film, and has low corrosion resistance.

[0030] The minority carrier lifetime of solar cells is also increasing, that is, the diffusion length of minority carriers is increasing. When the diffusion length of minority carriers is equal to or exceeds the thickness of silicon wafers, the recombination rate of the back surface has a significant impact on the characteristics of solar cells. After sintering, the back field forms a silicon-aluminum alloy. Aluminum is doped as a P-type in silicon, which can reduce the minority carrier recombination at the junction of metal and silicon, thereby increasing the open circuit voltage and short circuit current, and improving the response to infrared rays. The quality of the aluminum back field directly affects the output characteristics of solar cells.

[0031] After soaking the solder strip at 60°C for one week in a dilute acetic acid solution, the main grid line on the front of the cell turned yellow, the grid line on the back of the cell turned black, and the aluminum back field on the back of the cell fell off. The acetic acid produced by EVA will cause electrochemical corrosion of the tin-coated copper solder strip, corrode and oxidize the silver grid line on the surface of the cell to make it black, and corrode the aluminum back field of the cell while reducing the adhesion between the aluminum back field and the silicon wafer, seriously affecting the electrical performance of the battery. This will in turn reduce the electrical performance of the module. Therefore, in the future development of photovoltaic modules, it is necessary to study new packaging materials, new EVA formulations, or other measures to reduce the generation of acetic acid by EVA aging, so as to protect the battery from the harm of acetic acid and have a longer life.

[0032] More importantly, acetic acid interacts with metallization, often causing degradation of the interface between the front metal contact and the underlying silicon (Si) substrate. This leads to loss of cell performance and contact adhesion, increased contact resistance, and dark areas seen in electroluminescence (EL) imaging, so it is imperative to develop new pastes that are more resistant to acetic acid.

[0033] The introduction of Ti can improve the acetic acid performance of glass. The present application adjusts the low solubility of the electrode grid in acetic acid through the secondary glass (Pb-Ti-Si-B glass), improves the good chemical stability of the electrode, and resists acetic acid corrosion.

[0034] In some embodiments, the elements in the modifying additive include one or more of W, Ca, Mg, Zn, Bi and Ba.

[0035] In some embodiments, the main glass powder is Pb-Si-B glass. Taking the total molar percentage content of the main glass powder as 100 mol%, the main glass powder includes SiO2 15 mol% to 40 mol%, B2O3 18 mol% to 40 mol%, Al2O3 0 mol% to 20 mol%, PbO and BaO totaling 15 mol% to 45 mol%, RO 0 mol% to 12 mol%, and modifying additives 1 mol% to 20 mol%, wherein R is one or more of the alkali metals Li, Na or K.

[0036] In some embodiments, the elements in the modifying additive include one or more of Ca, Mg, Se, Ag, Zn, P, Ga and Fe.

[0037] In some embodiments, the slurry further comprises silver powder and an organic carrier. In the slurry, the mass fraction of the silver powder is 82% to 90%, and the mass fraction of the organic carrier is 8% to 15%. The silver powder is spherical silver powder, and the D50 of the silver powder is 1.4 to 2.0 um. D50 refers to the particle size corresponding to when the cumulative particle size distribution percentage of a sample reaches 50%. Its physical meaning is that particles with a particle size larger than it account for 50%, and particles with a particle size smaller than it also account for 50%. D50 is also called the median diameter or median particle size.

[0038] In some embodiments, the organic vehicle comprises an organic solvent, an organic resin and an additive, wherein the mass fraction of the organic solvent in the organic vehicle is 60% to 93%, the mass fraction of the organic resin is 5% to 20%, and the mass fraction of the additive is 2% to 20%.

[0039] In some embodiments, the glass powder includes a main glass powder and a secondary glass powder, and the preparation method of the glass powder includes:

[0040] The raw materials of various components are uniformly mixed, heated to be melted, and then cooled to obtain glass material; the glass material is ground and sieved to obtain glass powder.

[0041] In some embodiments, the preparation method specifically comprises:

[0042] The raw materials of various components are uniformly mixed, loaded into a platinum crucible, and melted at 900-1300° C. for 30-90 minutes. After cooling, glass material is obtained; the glass material is ground and sieved to obtain glass powder, and the D100 of the glass powder is less than or equal to 6 um.

[0043] In some embodiments, the slurry is applied to an N-type solar cell processed by a laser enhanced contact optimization process.

[0044] The present application also provides a photovoltaic module, which includes a first cover plate, a first adhesive film, a battery string, a second adhesive film and a second cover plate which are stacked, wherein the first adhesive film and the second adhesive film are EVA; the battery string includes a plurality of electrically connected solar cells, and the electrodes of the solar cells are formed by applying any of the solar cell conductive pastes described above.

[0045] Solar cells include, but are not limited to, PERC cells (Passivated Emitter Rear Cell), IBC (Interdigitated Back Contact), TOPCon (Tunnel Oxide Passivated Contact), HIT / HJT (Heterojunction Technology) cells, solar thin-film cells, and stacked cells, or any combination thereof. Among them, solar thin-film cells include, but are not limited to, perovskite solar thin-film cells, copper indium selenide solar thin-film cells, gallium arsenide solar thin-film cells, and cadmium sulfide solar thin-film cells. Stacked cells include, but are not limited to, perovskite cells stacked with crystalline silicon cells, perovskite cells stacked with perovskite cells, and perovskite cells stacked with thin-film cells.

[0046] Example:

[0047] The auxiliary glass powders GL001 to GL008 are prepared according to the material ratios in Table 1, and the main glass powders BL001 to BL005 are prepared according to the material ratios in Table 2. The material ratios of the glass powders in Tables 1 and 2 are all expressed in molar percentages. For example, in the auxiliary glass powder GL001, PbO 25 mol%, B2O 3 26 mol%, TiO 2 8 mol%, SiO 2 36 mol%, ZnO 4 mol%, and CaO 1 mol%.

[0048] Each component material is weighed by weight in mole percentage and mixed in a mixer; the material is put into a platinum crucible and melted at 900-1300°C using a lifting furnace for 30-90 minutes. After the glass state is homogenized, a molten water quenching method or a cold rolling method is used to obtain glass material. After the glass material is ground and sieved, secondary glass GL001-GL008 and main glass powder BL001-BL005 are obtained, and the glass powder D100 is ≤6um.

[0049] Among them, GL001~GL004, BL001~BL002 are melted at 1000℃ and kept warm for 60min; GL005 and BL003 are melted at 900℃ and kept warm for 30min; GL006, GL007, GL008, BL004 and BL005 are melted at 1300℃ and kept warm for 90min.

[0050] Table 1 Material ratio of auxiliary glass powder

[0051] raw material GL001 GL002 GL003 GL004 GL005 GL006 GL007 GL008 PbO 25 20 27 30 15 45 15 15 <![CDATA[B2O3]]> 26 18 28 15 18 18 30 18 <![CDATA[TiO2]]> 8 13 10 15 5 5 20 7 <![CDATA[Al2O3]]> 0 12 2 8 7 15 20 0 <![CDATA[SiO2]]> 36 25 20 18 45 9.5 0 23 <![CDATA[GeO2]]> 0 0.5 2 5 5 5.5 0 5 <![CDATA[Li2CO3]]> 0 1.5 0 0 1 1 0 5 <![CDATA[K2CO3]]> 0 0 0.5 0 0.5 0 2 2 <![CDATA[Na2CO3]]> 0 0.5 0 0 0 0 1 5 <![CDATA[Bi2O3]]> 0 5 7 0 0 0 3 0 ZnO 4 0 3.5 2 1 0 0 0 <![CDATA[TeO2]]> 0 1 0 5 0 0 5.5 5.5 <![CDATA[WO3]]> 0 0.5 0 0 1 0.5 3.5 3.5 BaO 0 2 0 0 0 0 0 7.5 MgO 0 1 0 0 1.5 0 0 2.5 CaO 1 0 0 2 0 0.5 0 1

[0052] Table 2 Main glass powder material ratio

[0053]

[0054]

[0055] Embodiment 1:

[0056] Weigh 88.5wt% silver powder, 9wt% organic carrier, 2.0wt% glass powder BL001, and 0.5wt% glass powder GL001. The organic carrier includes 75wt% organic solvent, 15wt% organic resin, and 10wt% additive. Premix the silver powder and the organic carrier with a planetary mixer, grind the slurry 6 times with a ceramic three-roll grinder, and test the grinding fineness with a scraper fineness meter. The slurry fineness is less than 10um, and filtered with a 250-mesh filter cloth to obtain the front electrode silver paste K1.

[0057] Embodiment 2:

[0058] Weigh 85.7wt% silver powder, 12wt% organic carrier, 1.5wt% glass powder BL001, and 0.8wt% glass powder GL002. The organic carrier includes 75wt% organic solvent, 15wt% organic resin, and 10wt% additive. Premix the silver powder and the organic carrier with a planetary mixer, grind the slurry 6 times with a ceramic three-roll grinder, and test the grinding fineness with a scraper fineness meter. The slurry fineness is less than 10um, and filtered with a 250-mesh filter cloth to obtain the front electrode silver paste K2.

[0059] Embodiment three:

[0060] Weigh 87.4wt% silver powder, 10wt% organic carrier, 2.2wt% glass powder BL002, and 0.4wt% glass powder GL003. The organic carrier includes 75wt% organic solvent, 15wt% organic resin, and 10wt% additive. Premix the silver powder and the organic carrier with a planetary mixer, grind the slurry 6 times with a ceramic three-roll grinder, and test the grinding fineness with a scraper fineness meter. The slurry fineness is less than 10um, and filtered with a 250-mesh filter cloth to obtain the front electrode silver paste K3.

[0061] Embodiment 4:

[0062] Weigh 88.8wt% silver powder, 9wt% organic carrier, 1.7wt% glass powder BL002, and 0.5wt% glass powder GL004. The organic carrier includes 75wt% organic solvent, 15wt% organic resin, and 10wt% additive. Premix the silver powder and the organic carrier with a planetary mixer, grind the slurry 6 times with a ceramic three-roll grinder, and test the grinding fineness with a scraper fineness meter. The slurry fineness is less than 10um, and filtered with a 250-mesh filter cloth to obtain the front electrode silver paste K4.

[0063] Embodiment five:

[0064] Weigh 82.3wt% silver powder, 15wt% organic carrier, 2.5wt% glass powder BL002, and 0.2wt% glass powder GL005. The organic carrier includes 60wt% organic solvent, 20wt% organic resin, and 20wt% additive. Premix the silver powder and the organic carrier with a planetary mixer, grind the slurry 6 times with a ceramic three-roll grinder, and test the grinding fineness with a scraper fineness meter. The slurry fineness is less than 10um, and filtered with a 250-mesh filter cloth to obtain the front electrode silver paste K5.

[0065] Embodiment six:

[0066] Weigh 82wt% silver powder, 15wt% organic carrier, 2.5wt% glass powder BL003, and 0.5wt% glass powder GL006. The organic carrier includes 93wt% organic solvent, 5wt% organic resin, and 2wt% additives, and the D50 of the silver powder is 1.4μ. Premix the silver powder and the organic carrier with a planetary mixer, grind the slurry 6 times with a ceramic three-roll grinder, and test the grinding fineness with a scraper fineness meter. The slurry fineness is less than 10um, and filter with a 250-mesh filter cloth to obtain the front electrode silver paste K6.

[0067] Embodiment seven:

[0068] Weigh 90wt% silver powder, 8wt% organic carrier, 1.5wt% glass powder BL004, and 0.5wt% glass powder GL007. The organic carrier includes 75wt% organic solvent, 15wt% organic resin, and 10wt% additives, and the D50 of the silver powder is 2.0μ. Premix the silver powder and the organic carrier with a planetary mixer, grind the slurry 6 times with a ceramic three-roll grinder, and test the grinding fineness with a scraper fineness meter. The slurry fineness is less than 10um, and filtered with a 250-mesh filter cloth to obtain the front electrode silver paste K7.

[0069] Embodiment eight:

[0070] Weigh 88wt% silver powder, 9wt% organic carrier, 2.0wt% glass powder BL005, and 1wt% glass powder GL008. The organic carrier includes 75wt% organic solvent, 15wt% organic resin, and 10wt% additives, and the D50 of the silver powder is 1.9μ. Premix the silver powder and the organic carrier with a planetary mixer, grind the slurry 6 times with a ceramic three-roll grinder, and test the grinding fineness with a scraper fineness meter. The slurry fineness is less than 10um, and filtered with a 250-mesh filter cloth to obtain the front electrode silver paste K8.

[0071] Comparative Example 1:

[0072] Weigh 89wt% silver powder, 9wt% organic carrier, and 2.0wt% glass powder BL001. The organic carrier includes 75wt% organic solvent, 15wt% organic resin, and 10wt% additive. Premix the silver powder and the organic carrier with a planetary mixer, grind the slurry 6 times with a ceramic three-roll grinder, and test the grinding fineness with a scraper fineness meter. The slurry fineness is less than 10um, and filtered with a 250-mesh filter cloth to obtain the front electrode silver paste B1.

[0073] Comparative Example 2:

[0074] Weigh 89wt% silver powder, 9wt% organic carrier, and 2.0wt% glass powder BL002. The organic carrier includes 75wt% organic solvent, 15wt% organic resin, and 10wt% additive. Premix the silver powder and the organic carrier with a planetary mixer, grind the slurry 6 times with a ceramic three-roll grinder, and test the grinding fineness with a scraper fineness meter. The slurry fineness is less than 10um, and filtered with a 250-mesh filter cloth to obtain the front electrode silver paste B2.

[0075] The slurries prepared in Examples 1-8 and Comparative Examples 1-2 were printed on N-type 182 silicon wafers using a Maiwei automatic printer, 100 wafers were printed with each slurry, sintered in a sintering furnace, and then processed by laser-enhanced contact optimization (LECO), and the cell IV test was performed to record the data.

[0076] Acetic acid test conditions:

[0077] 1) Place the cells to be corroded into a basket of corresponding size in a spacer-by-spacer manner; place two companion cells at the edge of the basket;

[0078] 2) Prepare acetic acid solution as required and pour it into a PP fresh-keeping box; then put the flower basket in the center of the fresh-keeping box, cover the box with the lid, buckle the buckle, and seal it with plastic film;

[0079] 3) Place the prepared acetic acid box in an 85°C oven, keep it warm for 8 hours, and then take out the battery cells for testing.

[0080] Formula: Eta attenuation value = (1-Eta after acetic acid / Eta before acetic acid) × 100%.

[0081] The experimental temperature, test time and acetic acid solution preparation method are shown in Table 3, and the measurement data are shown in Table 4.

[0082] Table 3 Acetic acid test experimental conditions

[0083]

[0084] "With fan" in Table 3 means that a fan is installed in the acetic acid box container to make the atmosphere concentration in the acetic acid box container uniform; "test time 8 hours" means that the battery cells are kept in the acetic acid box container for 8 hours.

[0085] Table 4 Experimental measurement data

[0086]

[0087]

[0088] like Figure 1 The figure shows the schematic diagram of the electrode cross section of the B1 cell before being placed in the acetic acid atmosphere. Figure 2 The figure shows the schematic diagram of the electrode cross section of the B1 battery cell after being exposed to acetic acid atmosphere. Figure 3 The figure shows the schematic diagram of the electrode cross section of the K2 battery cell before the acetic acid atmosphere. Figure 4 The figure shows the schematic diagram of the electrode cross section of the K2 battery cell in an acetic acid atmosphere. Figure 1-Figure 4 As shown, the cross-sections of the electrodes of the embodiment and the comparison example before acetic acid are roughly the same. After acetic acid, the metal electrode of the comparison example is more separated from the battery interface than that of the embodiment, and the bonding between the electrode contact metals is insufficient. The glass liquid of the comparison example is more separated from the conductive metal or the glass liquid is seriously degraded.

[0089] As shown in Table 4, Uoc is the open circuit voltage, FF is the fill factor, and Eta is the photoelectric conversion efficiency. The cell prepared by the slurry provided in the present application, after being placed in an acetic acid atmosphere, not only does the change in the open circuit voltage and fill factor of the cell be smaller, but also the attenuation value of the photoelectric conversion efficiency of the cell be smaller, and the photoelectric conversion efficiency of the cell after being placed in an acetic acid atmosphere remains above 20%. It can be seen that the slurry provided in the present application is more resistant to acetic acid.

[0090] The present application provides a solar cell conductive paste, the paste comprising a main glass powder and a secondary glass powder. The main glass powder is Pb-Si-B glass, the secondary glass powder is Pb-Ti-Si-B glass, the mass fraction of the main glass powder in the paste is 1.5% to 2.5%, and the mass fraction of the secondary glass powder is 0.2% to 1%. The paste also includes silver powder and an organic carrier, the mass fraction of the silver powder is 82% to 90%, and the mass fraction of the organic carrier is 8% to 15%.

[0091] The present application uses the auxiliary glass to adjust the low solubility of the electrode grid in acetic acid, improves the good chemical stability of the electrode, resists acetic acid corrosion, makes the electrode grid resistant to high temperature and high humidity, improves the reliability of the component, and solves the problem that the acetic acid produced by the decomposition of EVA affects the battery efficiency of the double-sided EVA component packaging battery. The present application also provides a photovoltaic component using the above slurry.

[0092] Similar parts between the embodiments provided in this application can be referenced to each other. The specific implementation methods provided above are only a few examples under the general concept of this application and do not constitute a limitation on the protection scope of this application. For those skilled in the art, any other implementation methods expanded based on the scheme of this application without creative work belong to the protection scope of this application.

Claims

1. A solar cell conductive paste, characterized in that: The slurry includes a main glass powder and a secondary glass powder. In the slurry, the mass fraction of the main glass powder is 1.5% to 2.5%, the mass fraction of the secondary glass powder is 0.2% to 1%, the secondary glass powder is Pb-Ti-Si-B glass, and based on the total molar percentage content of the secondary glass powder being 100 mol%, the secondary glass powder includes 15 mol% to 45 mol% of PbO, 5 mol% to 20 mol% of TiO2, 15 mol% to 50 mol% of SiO2 and GeO2 in total, 18 mol% to 30 mol% of B2O3, 0 mol% to 20 mol% of Al2O3, 0 mol% to 12 mol% of RO, and 1 mol% to 20 mol% of modified additives, wherein R is one or more of the alkali metals Li, Na or K.

2. The solar cell conductive paste according to claim 1, characterized in that: The elements in the modifying additive include one or more of W, Ca, Mg, Zn, Bi and Ba.

3. The solar cell conductive paste according to claim 1, characterized in that: The main glass powder is Pb-Si-B glass. Taking the total molar percentage content of the main glass powder as 100 mol%, the main glass powder includes SiO2 15 mol% to 40 mol%, B2O3 18 mol% to 40 mol%, Al2O3 0 mol% to 20 mol%, PbO and BaO totaling 15 mol% to 45 mol%, RO 0 mol% to 12 mol%, and modified additives 1 mol% to 20 mol%, wherein R is one or more of the alkali metals Li, Na or K.

4. The solar cell conductive paste according to claim 3, characterized in that: The elements in the modifying additive include one or more of Ca, Mg, Se, Ag, Zn, P, Ga and Fe.

5. The solar cell conductive paste according to claim 4, characterized in that: The slurry further comprises silver powder and an organic carrier. In the slurry, the mass fraction of the silver powder is 82% to 90%, and the mass fraction of the organic carrier is 8% to 15%.

6. The solar cell conductive paste according to claim 5, characterized in that: The organic carrier comprises an organic solvent, an organic resin and an additive. In the organic carrier, the mass fraction of the organic solvent is 60% to 93%, the mass fraction of the organic resin is 5% to 20%, and the mass fraction of the additive is 2% to 20%.

7. The solar cell conductive paste according to claim 1, characterized in that: The glass powder includes a main glass powder and a secondary glass powder, and the preparation method of the glass powder includes: The raw materials of various components are uniformly mixed, heated until melted, and cooled to obtain glass frit; The glass material is ground and sieved to obtain glass powder.

8. The solar cell conductive paste according to claim 7, characterized in that: The preparation method specifically comprises: The raw materials of various components are uniformly mixed, put into a platinum crucible, melted at 900-1300°C for 30-90 minutes, and then cooled to obtain glass material; The glass material is ground and screened to obtain glass powder, and the glass powder has a D100 of less than or equal to 6 um.

9. The solar cell conductive paste according to claim 1, characterized in that: The solar cell conductive paste is applied to an N-type solar cell processed by a laser enhanced contact optimization process.

10. A photovoltaic module, characterized in that: The photovoltaic module includes a first cover plate, a first adhesive film, a battery string, a second adhesive film and a second cover plate which are stacked, and the first adhesive film and the second adhesive film are EVA; the battery string includes a plurality of electrically connected solar cells, and the electrodes of the solar cells are formed by applying the solar cell conductive paste described in any one of claims 1 to 9.

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