Battery sheet and preparation method thereof, laminated battery and photovoltaic module

Abstract

The application provides a battery piece, a preparation method of the battery piece, a laminated battery and a photovoltaic module. The preparation method of the battery piece comprises the following steps: providing a semiconductor substrate, wherein the semiconductor substrate has a first surface and a second surface arranged oppositely; coating a conductive paste on the first surface and / or the second surface of the semiconductor substrate and sintering to form an electrode; wherein the conductive paste comprises 65-80% of conductive powder, 1-8% of glass powder, 5-10% of an organic carrier and a remainder of additives according to mass percentage; the glass powder contains lead elements; and the additives comprise a zirconium-containing compound and a gallium-containing compound. The battery piece prepared by the application can effectively improve the anti-acetic acid performance and photoelectric conversion efficiency of the battery piece and improve the long-term reliability of the battery piece.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to a solar cell and its preparation method, a tandem solar cell and a photovoltaic module. Background Technology

[0002] A photovoltaic (PV) cell is a clean power generation system that uses sunlight to generate electricity. The core component of a PV cell power generation system is the solar cell (also known as a solar cell), which can directly convert sunlight into electrical energy.

[0003] The fabrication process of solar cells requires the use of conductive paste to form electrodes, but the acetic acid resistance of solar cells prepared by current processes cannot meet the requirements. Summary of the Invention

[0004] This application provides a solar cell and its preparation method, a tandem solar cell and a photovoltaic module, which can effectively improve the acetic acid resistance and photoelectric conversion efficiency of the solar cell, and improve the long-term reliability of the solar cell.

[0005] In a first aspect, this application provides a method for preparing a battery cell, comprising the following steps; A semiconductor substrate is provided, the semiconductor substrate having a first surface and a second surface disposed opposite to each other; A conductive paste is coated onto the first and / or second surfaces of the semiconductor substrate and sintered to form an electrode. The conductive paste, by weight percentage, comprises: 65% to 80% conductive powder, 1% to 8% glass powder, 5% to 10% organic carrier, and the balance being additives. The glass powder contains lead. The additives include zirconium-containing compounds and gallium-containing compounds.

[0006] Secondly, embodiments of this application provide a battery cell, which is formed using the battery cell manufacturing method described in the first aspect, and the battery cell includes: A semiconductor substrate, the semiconductor substrate including a first surface and a second surface disposed opposite to each other; A first electrode is electrically connected to a first surface of the semiconductor substrate; and / or A second electrode is formed electrically connected to the second surface of the semiconductor substrate.

[0007] Thirdly, embodiments of this application provide a stacked battery, the stacked battery comprising: a perovskite top battery and a crystalline silicon bottom battery stacked sequentially, wherein the crystalline silicon bottom battery is a battery cell formed by the battery cell preparation method described in the first aspect or a battery cell described in the second aspect.

[0008] Fourthly, embodiments of this application provide a photovoltaic module, the photovoltaic module comprising: A battery string, wherein the battery string is formed by connecting multiple battery cells formed by the method of preparing battery cells described in the first aspect, or battery cells described in the second aspect, or stacked batteries described in the third aspect; An encapsulation layer covering the surface of the battery string, the material of the encapsulation layer comprising ethylene-vinyl acetate copolymer; A cover plate for covering the surface of the encapsulation layer away from the battery string.

[0009] The beneficial effects of this application are as follows: By adding additives including zirconium-containing compounds and gallium-containing compounds to the conductive paste, this application facilitates the thorough mixing and contact of the additives with the conductive powder and glass powder, improves the stability of the glass powder in the conductive paste, reduces the release of lead from the glass powder, reduces the reaction between lead and acetic acid, reduces the corrosion of the glass powder, and improves the acetic acid resistance of the conductive paste used to prepare solar cells. Furthermore, the synergistic effect between the zirconium-containing and gallium-containing compounds transforms the surface of the zirconium-containing compound from a "high defect, high recombination" state to a "low defect, low recombination" state, stabilizing the interface, improving the carrier transport capacity of the conductive paste used to prepare solar cells, increasing the photoelectric conversion efficiency of the solar cells, and simultaneously suppressing performance degradation caused by interface degradation, thus improving the long-term reliability of the solar cells. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the battery cell fabrication process provided in the embodiments of this application; Figure 2 This is a schematic diagram of the structure of the battery cell provided in the embodiments of this application; Figure 3 This is a schematic diagram of the structure of the stacked battery provided in the embodiments of this application; Figure 4 This is a schematic diagram of the structure of a photovoltaic module provided in an embodiment of this application; Figure 5 This is a schematic diagram of the initial electroluminescence of the battery cell in Example 1 before acetic acid testing; Figure 6 This is a schematic diagram of the electroluminescence of the battery cell after acetic acid treatment in Example 1; Figure 7 This is a schematic diagram of the initial electroluminescence of the battery cell in Comparative Example 1 before acetic acid testing. Figure 8 This is a schematic diagram of the electroluminescence of the battery cell after acetic acid treatment in Comparative Example 1.

[0011] In the attached image: 1000 - Photovoltaic modules; 100 - Solar cell; 10 - Semiconductor substrate; 20 - First passivation layer; 30 - Second passivation layer; 40 - First electrode; 50 - Second electrode; 200 - First cover plate; 300 - First encapsulating adhesive layer; 400 - Second encapsulating adhesive layer; 500 - Second cover plate; 2000-Stacked Battery; 2001-Perovskite Top Cell; 2002 - Crystalline silicon bottom cell. Detailed Implementation

[0012] In this embodiment of the application, unless otherwise stated, the character " / " indicates that the preceding and following objects are in an OR relationship. For example, A / B can represent A or B. "AND / OR" describes the relationship between the associated objects, indicating that three relationships can exist. For example, A AND / OR B can represent: A existing alone, A and B existing simultaneously, and B existing alone.

[0013] It should be noted that the terms "first" and "second" used in the embodiments of this application are used only for distinguishing descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated, nor should they be construed as indicating or implying order.

[0014] In the embodiments of this application, "at least one" means one or more, and "more than one" means two or more. Furthermore, "at least one of the following" or similar expressions refer to any combination of these items, which may include any combination of a single item or a plurality of items. For example, at least one of A, B, or C can represent: A, B, C, A and B, A and C, B and C, or A, B, and C. Each of A, B, and C can be an element itself or a set containing one or more elements.

[0015] In this application, terms such as "exemplary," "in some embodiments," and "in another embodiment" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the term "exemplary" is intended to present the concept in a concrete manner.

[0016] In the embodiments of this application, the term "equal to" can be used in conjunction with "greater than" to apply to technical solutions employing the condition of "greater than", and can also be used in conjunction with "less than" to apply to technical solutions employing the condition of "less than". It should be noted that when "equal to" is used with "greater than", it cannot be used with "less than"; and when "equal to" is used with "less than", it cannot be used with "greater than".

[0017] In related technologies, photovoltaic module encapsulation commonly uses EVA (Ethylene Vinyl Acetate) films for bonding, sealing, and insulation. EVA film molecules contain vinyl acetate active groups, which are prone to hydrolysis and thermal degradation under high-temperature lamination curing and subsequent long-term humid heat and UV aging conditions, continuously releasing small acidic acetic acid molecules. After gradually penetrating and migrating to the cell surface, acetic acid reacts with lead in the electrode glass phase to form lead acetate, gradually eroding the sintered glass phase structure inside the electrode, damaging electrode density and interfacial bonding, leading to electrode loosening, interfacial peeling, and deterioration of conductive pathways, thus exacerbating module power decay and reliability failure.

[0018] Therefore, embodiments of this application provide a method for preparing a battery cell. Figure 1 A schematic diagram of a battery cell fabrication process is shown, such as... Figure 1 As shown, the method for preparing solar cells includes the following steps: A semiconductor substrate is provided, the semiconductor substrate having a first surface and a second surface disposed opposite to each other; Electrodes are formed by coating a conductive paste onto the first and / or second surfaces of a semiconductor substrate and sintering it. The conductive paste, by weight percentage, comprises: 65% to 80% conductive powder, 1% to 8% glass powder, 5% to 10% organic carrier, and the remainder additives. Glass powder contains lead; Additives include zirconium-containing compounds and gallium-containing compounds.

[0019] In the aforementioned scheme, this application, by adding additives including zirconium-containing compounds and gallium-containing compounds to the conductive paste, facilitates thorough mixing and contact between the additives and conductive powders and glass powders. This improves the stability of the glass powder in the conductive paste, reduces the release of lead from the glass powder, minimizes the reaction between lead and acetic acid, reduces glass powder corrosion, and enhances the acetic acid resistance of the conductive paste used to prepare solar cells. Furthermore, the synergistic effect between the zirconium-containing and gallium-containing compounds transforms the surface of the zirconium-containing compound from a "high defect, high recombination" state to a "low defect, low recombination" state, stabilizing the interface, improving the carrier transport capacity of the conductive paste used to prepare solar cells, increasing the photoelectric conversion efficiency of the solar cells, and simultaneously suppressing performance degradation caused by interface degradation, thus improving the long-term reliability of the solar cells.

[0020] It should be noted that the additives in this application are added to the conductive paste, not the glass powder. The zirconium-containing compound is a dense, inert material with extremely low porosity and a continuous, dense lattice after film formation, which can physically block the penetration of small acetic acid molecules. At the same time, it has extremely strong acid resistance, does not react with acetic acid, and can also block the migration channels of acidic ions, thereby effectively preventing the intrusion of acetic acid generated by the degradation of ethylene-vinyl acetate copolymer into the corrosion interface. However, the original interface of the zirconium-containing compound has a large number of lattice defects and dangling bonds. When these are distributed in the conductive paste and come into contact with the photoelectric interface of the semiconductor substrate, they are prone to forming deep-level recombination centers, which aggravate the non-radiative recombination of charge carriers. This application also adds gallium-containing compounds to the conductive paste, which fills and passivates the interface defects of the zirconium-containing compound, saturates and seals the dangling bonds, eliminates a large number of deep-level recombination centers, and significantly improves the integrity of the interface lattice. This transforms the interface from a high-recombination deterioration state to a low-recombination stable state, while blocking external erosion and achieving long-term stability of the interface structure and electrical properties of the conductive paste.

[0021] The preparation method of the battery cell of the present invention will be described in detail below.

[0022] S1 provides a semiconductor substrate having opposing first and second surfaces.

[0023] In some embodiments, the semiconductor substrate is an N-type crystalline silicon substrate (or silicon wafer), but it can also be a P-type crystalline silicon substrate (silicon wafer). The crystalline silicon substrate may be, for example, a polycrystalline silicon substrate, a monocrystalline silicon substrate, a microcrystalline silicon substrate, or a silicon carbide substrate. This application does not limit the specific type of semiconductor substrate. Optionally, the semiconductor substrate is an N-type crystalline silicon substrate, and the doping element of the N-type crystalline silicon substrate is at least one of nitrogen, phosphorus, arsenic, antimony, or bismuth.

[0024] In some embodiments, the thickness of the semiconductor substrate is 60μm to 240μm, specifically 60μm, 80μm, 90μm, 100μm, 120μm, 150μm, 200μm or 240μm, etc., and is not limited here.

[0025] In some embodiments, the first surface of the semiconductor substrate corresponds to the front side of the solar cell, which is the sun-facing surface (i.e., the light-receiving surface). In other embodiments, the first surface of the semiconductor substrate corresponds to the back side of the solar cell, which is the surface facing away from the sun (i.e., the back-shielded surface). The following description uses the example of the first surface corresponding to the front side of the solar cell.

[0026] The process after S1 and before S2 includes: forming a first passivation layer on a first surface of the semiconductor substrate and forming a second passivation layer on a second surface of the semiconductor substrate.

[0027] In some embodiments, the first passivation layer may be, but is not limited to, a single-layer oxide layer or a multi-layer structure such as silicon oxide, silicon nitride, silicon oxynitride, or aluminum oxide. Of course, other types of passivation layers can also be used, and the present invention does not limit the specific material of the first passivation layer. The first passivation layer can reduce the minority carrier concentration on the substrate surface through the passivation effect, suppress carrier recombination on the surface of the solar cell, thereby reducing the surface recombination rate. It can also reduce series resistance and improve electron transport capability.

[0028] In some implementations, plasma-enhanced chemical vapor deposition can be used to deposit the first passivation layer. Of course, other methods can also be used, such as organic chemical vapor deposition.

[0029] In some embodiments, the second passivation layer includes, but is not limited to, single-layer or multi-layer oxide structures such as silicon oxide, silicon nitride, silicon oxynitride, and aluminum oxide. Of course, other types of passivation layers can also be used, and the specific material of the second passivation layer is not limited in this invention. The second passivation layer can reduce the minority carrier concentration on the substrate surface through the passivation effect, suppress carrier recombination on the surface of the solar cell, thereby reducing the surface recombination rate. It can also reduce series resistance and improve electron transport capability. It should be noted that the second passivation layer can also reduce incident light reflection; in some instances, it can be called an anti-reflection layer. For example, a chain magnetron sputtering process can be used to form the second passivation layer.

[0030] In some implementations, plasma-enhanced chemical vapor deposition can be used to deposit the second passivation layer. Of course, other methods can also be used, such as organic chemical vapor deposition.

[0031] S2, Prepare conductive paste, apply conductive paste to the first and / or second surfaces of a semiconductor substrate, sinter to form an electrode.

[0032] S21, by mass percentage, 65%~80% conductive powder, 1%~8% glass powder, 5%~10% organic carrier and the balance additives are mixed to obtain a premix.

[0033] In some embodiments, S21 may specifically be: adding 5% to 10% organic carrier and 1% to 8% glass powder to a planetary mixer for a first stirring process to ensure that the mixture is fully dispersed and uniform; then adding 65% to 80% conductive powder and the remainder additive powder to the planetary mixer for a second stirring process to obtain a premix.

[0034] In some embodiments, the stirring speed for one stirring process is 300 rpm to 800 rpm, and the stirring time for one stirring process is 10 min to 30 min.

[0035] In some embodiments, the secondary stirring speed is 700 rpm to 1300 rpm, and the secondary stirring time is 10 min to 30 min.

[0036] Of course, the mixing order of the materials in the above premix can also be used, as long as the materials are mixed evenly. This application does not impose any restrictions on this.

[0037] In some embodiments, the mass percentage of conductive powder in the conductive slurry is 65% to 80%, specifically 65%, 68%, 70%, 73%, 75%, 78%, 80%, or any value within the range of any two of the above values.

[0038] In some embodiments, the conductive powder includes at least one of silver powder, copper powder, gold powder, nickel powder, and aluminum powder.

[0039] In some embodiments, the conductive powder includes at least one of spherical powder and flake powder.

[0040] In some embodiments, the mass percentage of glass powder in the conductive paste is 1% to 8%, specifically 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, or any value within the range of any two of the above values.

[0041] In some embodiments, the glass powder includes at least one of lead-tellurium system glass powder, lead-bismuth-silicon system glass powder, lead-vanadium system glass powder, and lead-boron system glass powder.

[0042] This application uses glass powder containing lead. The presence of lead significantly reduces the softening temperature of the glass powder and widens its sintering window. It also imparts low viscosity and high wettability to the glass powder melt, enabling tight adhesion and chemically inert encapsulation of semiconductor substrates even under low-temperature sintering processes. However, lead readily reacts with acetic acid molecules precipitated from the EVA film to form lead acetate. This application addresses this by adding zirconium-containing and gallium-containing compounds to the conductive paste, thereby suppressing lead acetate formation, improving the acetic acid resistance of the solar cell, and ensuring the conductive paste provides sufficient charge carrier transport for the solar cell, ultimately enhancing its photoelectric conversion efficiency.

[0043] In some embodiments, the organic carrier has a mass percentage of 5% to 10% in the conductive paste, specifically 5%, 6%, 7%, 8%, 9%, 10%, or any value within the range of any two of the above values.

[0044] In some embodiments, the organic carrier includes a resin and a solvent.

[0045] In some embodiments, the resin is dispersed in a solvent and stirred at 70°C to 100°C for 0.2 to 2 hours to obtain an organic carrier.

[0046] In some embodiments, the resin includes at least one of ethyl cellulose, cellulose acetate butyrate, and hydrogenated rosin.

[0047] In some embodiments, the resin content in the organic carrier is 5% to 10% by mass, specifically 5%, 6%, 7%, 8%, 9%, 10%, or any value within the range of any two of the above values.

[0048] In some embodiments, the solvent includes an organic solvent with a boiling point of 200°C to 300°C, and the organic solvent includes at least one of alcohol ester-12, diethylene glycol butyl ether acetate, divalent ester and tributyl citrate.

[0049] In some embodiments, the solvent content in the organic carrier is 90% to 95% by mass, specifically 90%, 91%, 92%, 93%, 94%, 95%, or any value within the range of any two of the above values.

[0050] In some embodiments, the additive's mass percentage in the conductive paste is 1% to 2%, specifically 1%, 1.3%, 1.5%, 1.8%, 2%, or any value within the range of any two of the above values. Controlling the mass percentage of the additive in the conductive paste within the above range can improve the acetic acid resistance of the solar cell while ensuring its conductivity and contactability.

[0051] In some embodiments, the mass ratio of the zirconium-containing compound to the gallium-containing compound is 1:(2~4), specifically 1:2, 1:2.5, 1:3, 1:3.5, 1:4, or any value within the range of any two of the above values. Controlling the mass ratio of the zirconium-containing compound to the gallium-containing compound within the above range ensures that the gallium-containing compound can effectively passivate the interface defects and dangling bonds of the zirconium-containing compound, thereby improving the interface lattice integrity of the electrode.

[0052] In some embodiments, the zirconium-containing compound includes zirconium dioxide. Zirconium dioxide has good density, which is beneficial to improving the structural stability of glass powder in conductive paste, making it less likely for lead in the glass powder to be released. Moreover, zirconium dioxide can also adjust the coefficient of thermal expansion of the conductive paste to match the semiconductor substrate, preventing the conductive paste from cracking or warping during subsequent sintering.

[0053] In some embodiments, the mass percentage of zirconium dioxide in the conductive paste is 0.15% to 0.5%, specifically 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, or any value within the range of any two of the above values. Controlling the mass percentage of zirconium dioxide in the conductive paste within the above range is beneficial for improving the structural stability of the glass powder in the conductive paste, making it less likely for lead in the glass powder to be released; at the same time, it ensures the conductivity of the conductive paste.

[0054] In some embodiments, the gallium-containing compound includes at least one of gallium arsenide, gallium nitride, and gallium oxide. These gallium-containing compounds are stable and have good compatibility with other components in the conductive paste, ensuring the electrochemical performance of the conductive paste while improving the interface integrity of the conductive paste, thereby enhancing the photoelectric conversion efficiency and long-term reliability of the solar cell.

[0055] In some embodiments, the mass percentage of the gallium-containing compound in the conductive paste is 0.65% to 1.5%, specifically 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, or any value within the range of any two of the above values. Controlling the mass percentage of the gallium-containing compound in the conductive paste within the above range is beneficial for improving the interfacial lattice integrity of the conductive paste, while ensuring the conductivity of the conductive paste.

[0056] In some embodiments, the morphology of the additive includes at least one of spherical and near-spherical shapes, which ensures uniform dispersion of the additive in the conductive paste and achieves effective contact between the additive and the glass powder.

[0057] In some embodiments, the median particle size of the zirconium-containing compound is 10 nm to 50 nm, specifically it can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm or any value within the range of any two of the above values.

[0058] In some embodiments, the median particle size of the gallium-containing compound is 0.5 μm to 3 μm, specifically it can be 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm or any value within the range of any two of the above values.

[0059] It should be noted that the median particle size mentioned in this application is the particle size corresponding to 50% of the cumulative volume distribution of the powder, measured by a laser particle size analyzer.

[0060] Controlling the median particle size of zirconium-containing and gallium-containing compounds within the above-mentioned range is beneficial to improving the dispersibility of additives and reducing the flow resistance during the sintering of conductive pastes.

[0061] In some embodiments, the additive may also include at least one of dispersants, thixotropic agents, sintering aids, adhesion promoters, and stabilizers to improve the performance of the conductive paste.

[0062] In some embodiments, the dispersant includes, but is not limited to, stearic acid, oleic acid, palmitic acid, triethanolamine, ethanolamine, etc. The dispersant can improve the agglomeration and sedimentation of conductive powder and glass powder, and improve the dispersion uniformity of conductive powder and glass powder in organic carrier.

[0063] In some embodiments, the thixotropic agent includes, but is not limited to, hydrogenated castor oil, fumed silica, organobentonite, polyamide wax, ethyl cellulose, etc. The thixotropic agent can adjust the viscosity and thixotropy of the conductive paste and improve the storage and settling stability of the conductive paste.

[0064] In some embodiments, sintering aids include, but are not limited to, molybdenum oxide, tungsten oxide, zinc oxide, bismuth oxide, etc. These sintering aids can reduce the sintering temperature of the conductive paste and decrease the interfacial contact resistance.

[0065] In some embodiments, adhesion promoters include, but are not limited to, silane coupling agents, titanate coupling agents, and nano-silica. These adhesion promoters can enhance the interfacial bonding between the electrode and the semiconductor substrate.

[0066] In some embodiments, stabilizers include, but are not limited to, benzotriazole, lecithin, organophosphorus compounds, etc. These stabilizers can prevent the oxidation of conductive powder, inhibit the performance degradation of conductive slurry, and improve storage and damp heat aging stability.

[0067] In some embodiments, mixing is carried out under stirring conditions to ensure that the components are uniformly dispersed.

[0068] In some embodiments, the stirring speed is 700 rpm to 1300 rpm, and the stirring time is 10 min to 2 h.

[0069] S22, the premixed material is rolled to obtain the precursor.

[0070] The rolling process specifically includes: transferring the premixed material to a three-roll mill for grinding. The gaps between the rollers are set sequentially to 50μm, 25μm, and 15μm, and each is repeatedly ground 5 times until the fineness is less than 10μm when checked with a fineness plate.

[0071] S23. The precursor is subjected to vacuum degassing treatment to obtain conductive slurry.

[0072] The vacuum degassing process specifically includes: placing the precursor in a vacuum degassing machine at a vacuum level below 0 MPa for 10 to 30 minutes, then restoring it to normal pressure, and then allowing it to stand and mature at 10°C to 40°C for 12 to 36 hours to obtain the conductive slurry.

[0073] S24. A conductive paste is applied to the first and / or second surfaces of a semiconductor substrate and sintered to form an electrode.

[0074] In some implementations, a conductive paste is coated only on the second surface of the semiconductor substrate, and electrodes are formed by sintering, resulting in a back-contact solar cell.

[0075] In some embodiments, conductive paste is coated on the first and second surfaces of a semiconductor substrate, and then sintered to form a first electrode on the first surface of the semiconductor substrate and a second electrode on the second surface of the semiconductor substrate, resulting in a bifacial solar cell.

[0076] The following example illustrates the preparation of a battery cell by coating conductive paste on the first and second surfaces of a semiconductor substrate, including the following steps: first, a conductive paste is coated on the first surface of the semiconductor substrate and dried; then, a conductive paste is coated on the second surface of the semiconductor substrate, dried, and sintered.

[0077] In some embodiments, coating includes, but is not limited to, at least one of screen printing, plate printing, inkjet printing, and blade coating.

[0078] In some embodiments, the drying and sintering steps after printing the front silver electrode paste are carried out in a tunnel furnace, with the temperature of the tunnel furnace being distributed in a gradient, and the time spent in the tunnel furnace being 1 min to 3 min.

[0079] The sintering in this application is carried out in an inert gas atmosphere, such as nitrogen or argon. Sintering in an inert atmosphere can suppress the oxidation of gallium-containing compounds and the volatilization of gallium.

[0080] In some embodiments, the sintering process includes: first heating from room temperature to 150℃~250℃, holding at that temperature for 1s~3s, then heating to 300℃~450℃, holding at that temperature for 1s~3s, then heating to 500℃~580℃, holding at that temperature for 3s~5s, and then cooling down to room temperature.

[0081] It should be noted that room temperature refers to 23±2℃.

[0082] This application achieves slow heating through stepwise heating, which helps reduce the decomposition and volatilization of zirconium-containing and gallium-containing compounds, while also reducing the generation of defects such as bubbling and pinholes in the conductive paste. This facilitates the uniform mixing and sintering of the conductive paste in a mild environment, and improves the density and adhesion of the sintered electrode.

[0083] In the above sintering process, the heating rate from room temperature to 150℃~250℃ is denoted as S1℃ / s, the heating rate from 500℃~580℃ is denoted as S2℃ / s, and the cooling rate from room temperature to S3℃ / s, where S1≤S2<S3. The slow heating method used in this application allows the organic solvents and organic carriers in the conductive paste to slowly and fully volatilize and decompose, avoiding the formation of pinholes, bubbles, and cracks in the paste caused by rapid heating. At the same time, it allows the glass powder to gradually soften, improving the structural stability of the glass powder in the conductive paste and making it less likely for lead to be released from the glass powder. The subsequent rapid cooling can shorten the residence time of the material in the high-temperature range, inhibit abnormal grain growth, improve lattice integrity, and reduce microcracks, lattice distortion, and interface mismatch problems.

[0084] In some implementations, S1℃ / s is less than or equal to 2℃ / s, and S1℃ / s can specifically be 0.5℃ / s, 0.8℃ / s, 1℃ / s, 1.2℃ / s, 1.5℃ / s, 1.8℃ / s, 2℃ / s, or any value within the range of any two of the above values.

[0085] In some implementations, S2℃ / s is 2℃ / s to 3℃ / s. Specifically, S2℃ / s can be 2℃ / s, 2.2℃ / s, 2.5℃ / s, 2.6℃ / s, 2.8℃ / s, 3℃ / s, or any value within the range of any two of the above values.

[0086] In some implementations, S3℃ / s is 10℃ / s to 50℃ / s, and 32℃ / s can specifically be 10℃ / s, 15℃ / s, 20℃ / s, 25℃ / s, 30℃ / s, 35℃ / s, 40℃ / s, 45℃ / s, 50℃ / s, or any value within the range of any two of the above values.

[0087] In some embodiments, the peak sintering temperature is 500℃~580℃, specifically 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, etc., and is not limited thereto. Controlling the peak sintering temperature within the above range avoids excessively high temperatures that could lead to the decomposition and volatilization of gallium-containing compounds, resulting in insufficient content and hindering the effective performance of acetic acid resistance and improved carrier transport capacity.

[0088] This application embodiment also provides a battery cell, the battery cell comprising: Semiconductor substrate, the semiconductor substrate includes a first surface and a second surface disposed opposite to each other; The first electrode forms an ohmic contact with the first surface of the semiconductor substrate; and / or A second electrode that forms an ohmic contact with the second surface of a semiconductor substrate; At least one of the first electrode and the second electrode is formed using the aforementioned conductive paste.

[0089] The conductive paste of this application can improve the acetic acid resistance of the conductive paste. The first electrode and / or the second electrode formed by the conductive paste of this application can maintain high stability, while improving the interfacial stability of the first electrode and / or the second electrode, which is beneficial to reducing the electrochemical degradation of the solar cell and improving the photoelectric conversion efficiency of the solar cell.

[0090] The solar cells of this application can be one or any combination of PERC (Passivated Emitter Rear Ce1l), IBC (Interdigitated Back Contact), TOPCon (Tunnel Oxide Passivated Contact), and HIT / HTT (Heterojunction Technology) cells. It is understood that all of the above-mentioned solar cells can be prepared using the methods described in this application.

[0091] It should be noted that, based on the above-mentioned different types of battery cells, the first and second surfaces of the semiconductor substrate can also be provided with different film layer structures as needed, and this application does not impose any restrictions here.

[0092] Specifically, Figure 2 A schematic diagram of a battery cell structure is shown, such as... Figure 2 As shown, the battery cell 100 includes a first electrode 40, a first passivation layer 20, a semiconductor substrate 10, a second passivation layer 30, and a second electrode 50.

[0093] It should be noted that in some embodiments, the battery cell 100 only contains the second electrode 50.

[0094] Based on the same inventive concept, this application also provides a stacked battery. Figure 3 This is a schematic diagram of the structure of a stacked battery, as shown below. Figure 3 As shown, the stacked solar cell 2000 includes a perovskite top solar cell 2001 and a crystalline silicon bottom solar cell 2002 stacked sequentially along a preset direction; wherein, the crystalline silicon bottom solar cell 2002 includes the solar cell 100 provided in the above embodiments of the present invention. It should be noted that the stacked solar cell 2000 provided by the present invention has the technical effects of the solar cell 100 in the present invention, and the repeated parts will not be described again.

[0095] Based on the same inventive concept, this application also provides a photovoltaic module, which includes: A battery string is composed of multiple of the aforementioned battery cells connected together. Encapsulation layer, which covers the surface of the battery string; Cover plate, used to cover the surface of the encapsulation layer away from the battery string.

[0096] Specifically, Figure 4 A schematic diagram of a photovoltaic module is shown below. Please refer to [link / reference]. Figure 4 The photovoltaic module 1000 includes a first cover plate 200, a first encapsulating layer 300, a solar cell string, a second encapsulating layer 400, and a second cover plate 500.

[0097] In some embodiments, the solar cell string includes a plurality of cells 100 as described above connected by conductive strips, and the connection between the cells 100 can be partially stacked or spliced.

[0098] In some embodiments, the first cover plate 200 and the second cover plate 500 can be transparent or opaque covers, such as glass covers or plastic covers.

[0099] The first encapsulating adhesive layer 300 is in contact with and bonded to the first cover plate 200 and the battery string on both sides, respectively. The second encapsulating adhesive layer 400 is in contact with and bonded to the second cover plate 500 and the battery string on both sides, respectively. The first encapsulating adhesive layer 300 and the second encapsulating adhesive layer 400 can be ethylene-vinyl acetate copolymer (EVA) film, polyethylene octene coelastomer (POE) film, or polyethylene terephthalate (PET) film, respectively.

[0100] The photovoltaic module 1000 can also be fully encapsulated on the sides, that is, the sides of the photovoltaic module 1000 are completely covered and encapsulated with encapsulating tape to prevent lamination shift during the lamination process.

[0101] The photovoltaic module 1000 also includes an edge sealing component, which is fixedly encapsulated on a portion of the edge of the photovoltaic module 1000. This edge sealing component can be fixedly encapsulated on the edge of the photovoltaic module 1000 near a corner. The edge sealing component can be a high-temperature resistant tape. This high-temperature resistant tape has excellent high-temperature resistance properties and will not decompose or detach during lamination, ensuring reliable encapsulation of the photovoltaic module 1000. The two ends of the high-temperature resistant tape are respectively fixed to the second cover plate 500 and the first cover plate 200. The two ends of the high-temperature resistant tape can be bonded to the second cover plate 500 and the first cover plate 200 respectively, while the middle portion can limit the side of the photovoltaic module 1000, preventing lamination displacement of the photovoltaic module 1000 during the lamination process.

[0102] The following are specific embodiments illustrating this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0103] Example 1 (1) In a planetary mixer, add 10 parts by weight of organic carrier (model OS-200), 8 parts by weight of high-lead glass powder (model F-502, with lead oxide content of 78% in the high-lead glass powder), 2 parts by weight of hydrogenated castor oil and 2 parts by weight of stearic acid in sequence and stir for 20 minutes at a stirring speed of 500 rpm to fully disperse and obtain a mixed carrier.

[0104] (2) Place 77 parts by weight of spherical silver powder in an oven at 105°C and dry for 2 hours to remove surface adsorbed moisture. Add 75 parts by weight of spherical silver powder, 0.25 parts by weight of zirconium oxide powder and 0.75 parts by weight of gallium arsenide powder to a planetary mixer and stir at 1000 rpm for 20 minutes to obtain a premix.

[0105] (3) Transfer the premixed material to a three-roll mill for grinding. The gap between the rollers is set to 50μm, 25μm and 15μm respectively. Grind each roller repeatedly for 5 times until the fineness is less than 10μm when checked by scraping with a fineness plate. Place the ground material in a vacuum degassing machine at a vacuum degree of -0.095MPa for 20 minutes, then restore normal pressure, and then let the slurry stand at 30℃ for 24 hours to obtain conductive slurry.

[0106] (4) The conductive paste is screen-printed onto the upper surface of the silicon wafer, which is then placed in a tunnel furnace. In a nitrogen atmosphere, the temperature is first increased from room temperature to 250°C at a rate of 1.5°C / s, held for 2s, then increased to 300°C at the same rate, held for 2s, then increased to 580°C at a rate of 3°C / s, held for 5s, and then cooled to room temperature at a rate of 30°C / s to obtain the first electrode. The conductive paste is screen-printed onto the lower surface of the silicon wafer, which is then placed in a tunnel furnace. In a nitrogen atmosphere, the temperature is first increased from room temperature to 250°C at a rate of 1.5°C / s and held for 2 seconds. The temperature is then increased to 300°C at the same rate and held for 2 seconds. The temperature is then increased to 580°C at a rate of 3°C / s and held for 5 seconds. Finally, the temperature is decreased to room temperature at a rate of 30°C / s to obtain the second electrode, which is the solar cell.

[0107] The conductive paste of Example 1 includes conductive powder, lead-containing glass powder, organic carrier and additives, including zirconium oxide and gallium arsenide.

[0108] Example 2 Unlike Example 1, the conductive paste, by weight percentage, comprises: 0.5 parts zirconium oxide powder, 1 part gallium arsenide powder, 9.5 parts organic carrier, 8 parts high-lead glass powder, 2 parts hydrogenated castor oil, 2 parts stearic acid, and 77 parts spherical silver powder.

[0109] Example 3 Unlike Example 1, the conductive paste, by weight percentage, comprises: 0.5 parts zirconium oxide powder, 1.5 parts gallium arsenide powder, 9 parts organic carrier, 8 parts high-lead glass powder, 2 parts hydrogenated castor oil, 2 parts stearic acid, and 77 parts spherical silver powder.

[0110] Example 4 Unlike Example 1, the conductive paste, by weight percentage, comprises: 0.3 parts zirconium oxide powder, 1.2 parts gallium arsenide powder, 9.5 parts organic carrier, 8 parts high-lead glass powder, 2 parts hydrogenated castor oil, 2 parts stearic acid, and 77 parts spherical silver powder.

[0111] Example 5 Unlike Example 1, the conductive paste, by mass percentage, comprises: 0.3 parts zirconium oxide powder, 0.3 parts gallium arsenide powder, 10 parts organic carrier, 8 parts high-lead glass powder, 2 parts hydrogenated castor oil, 2 parts stearic acid, and 77.4 parts spherical silver powder.

[0112] Example 6 Unlike Example 1, the conductive paste, by mass percentage, comprises: 1 part zirconium oxide powder, 2 parts gallium arsenide powder, 8 parts organic carrier, 8 parts high-lead glass powder, 2 parts hydrogenated castor oil, 2 parts stearic acid, and 77 parts spherical silver powder.

[0113] Comparative Example 1 Unlike Example 1, no zirconium oxide and gallium arsenide are added. The conductive paste comprises: 10 parts by weight of organic carrier, 8 parts by weight of high-lead glass powder, 2 parts by weight of hydrogenated castor oil, 2 parts by weight of stearic acid, and 78 parts by weight of spherical silver powder.

[0114] Comparative Example 2 Unlike Example 1, gallium arsenide is not added, and the conductive paste includes: 0.5 parts by weight of zirconium oxide powder, 9.5 parts by weight of organic carrier, 8 parts by weight of high-lead glass powder, 2 parts by weight of hydrogenated castor oil, 2 parts by weight of stearic acid, and 78 parts by weight of spherical silver powder.

[0115] Comparative Example 3 Unlike Example 1, no zirconium oxide powder is added. The conductive paste comprises: 1 part by weight of gallium arsenide powder, 9 parts by weight of organic carrier, 8 parts by weight of high-lead glass powder, 2 parts by weight of hydrogenated castor oil, 2 parts by weight of stearic acid, and 78 parts by weight of spherical silver powder.

[0116] Acetic acid decay rate test: The solar cells prepared in each embodiment and comparative example were tested using a solar simulator under standard test conditions (AM1.5 spectrum, irradiance 1000 W / m²). 2 The initial photoelectric conversion efficiency E0 was tested at an ambient temperature of 25℃±1℃. The cells were then immersed in a 3% acetic acid solution at 60℃ for 48 hours. After removal, they were rinsed three times with deionized water and dried in a 60℃ oven for 10 minutes. The dried cells were then placed back in a solar simulator under identical standard test conditions to test the post-treatment photoelectric conversion efficiency E1. The acetic acid degradation rate was calculated using the following formula: Acetic acid decay rate = (E0 - E1) / E0 100%

[0117] Three cells were tested for each example or comparative example, and the average acetic acid degradation rate was calculated. The test results are shown in Table 1.

[0118] Table 1. Acetic acid degradation results of the battery cells prepared in each embodiment and comparative example.

[0119] As shown in Table 1, compared with Comparative Examples 1 to 3, Examples 1 to 6 of this application, by adding additives including zirconium-containing compounds and gallium-containing compounds to the conductive paste, can not only improve the stability of the glass powder in the conductive paste and improve the acetic acid resistance of the conductive paste in the preparation of the battery cell, but also improve the photoelectric conversion efficiency of the battery cell and significantly reduce the acetic acid degradation rate of the battery cell.

[0120] According to the test data of Example 5, the mass ratio of zirconium oxide powder to gallium arsenide powder in Example 5 is 1:1, and the mass percentage of additives is slightly lower, which leads to a slight increase in the acetic acid degradation rate of the battery cell.

[0121] According to the test data of Example 6, the mass percentage of the additive in Example 6 was slightly higher, which led to a slight increase in the acetic acid degradation rate of the battery cell.

[0122] According to the test data of Comparative Example 1, the average acetic acid degradation rate of the prepared battery cells was significantly increased to 29.3% when the additives (zirconia and gallium arsenide) specified in this application were not added to the conductive paste.

[0123] The solar cells prepared in Example 1 and Comparative Example 1 were immersed in a 0.3% acetic acid solution and soaked at a constant temperature of 60°C for 8 hours. After removal, they were rinsed three times with deionized water and dried in a 60°C oven for 10 minutes. The dried solar cells were placed on the sample stage of an electroluminescence analyzer, and the positive and negative electrodes of the solar cells were connected with probes. A forward bias voltage (voltage 0.8V, current density 40mA / cm²) was applied. 2 An electroluminescent image was obtained by exposing the image for 2 seconds using a CCD camera in a dark room.

[0124] Figure 5 This is a schematic diagram of the initial electroluminescence of the battery cell in Example 1 before acetic acid testing. Figure 6 This is a schematic diagram of the electroluminescence of the battery cell in Example 1 after acetic acid treatment, as shown. Figure 5 and Figure 6 As shown, the overall brightness of the battery cell image after acetic acid treatment in Example 1 is relatively uniform and is basically consistent with the image without acetic acid treatment, indicating that the battery cell of Example 1 has less acetic acid attenuation and good acid resistance. Figure 7 This is a schematic diagram of the initial electroluminescence of the solar cell in Comparative Example 1. Figure 8 This is a schematic diagram of the electroluminescence of the battery cell in Comparative Example 1 after acetic acid treatment, as shown below. Figure 7 and Figure 8 As shown in Comparative Example 1, the black coverage area of ​​the solar cell after acetic acid treatment is significantly increased, indicating a larger dark spot area. This suggests that acetic acid corrosion leads to more composite defects or electrode damage within the solar cell. Therefore, the solar cell prepared in this application can effectively suppress acetic acid degradation and improve the acid resistance of the solar cell.

[0125] According to the test data of Comparative Example 2, when gallium arsenide powder is not added to the conductive paste, but only zirconium oxide powder is added, the solar cell has a certain resistance to acetic acid. However, the increased recombination of the solar cell leads to an excessively high acetic acid degradation rate.

[0126] According to the test data of Comparative Example 3, if gallium arsenide powder is added to the conductive paste without adding zirconium oxide powder, the battery cell has almost no resistance to acetic acid.

[0127] The above description is merely a specific embodiment of this application. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application. The protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A method for preparing a battery cell, characterized in that, Includes the following steps: A semiconductor substrate is provided, the semiconductor substrate having a first surface and a second surface disposed opposite to each other; A conductive paste is coated onto the first and / or second surfaces of the semiconductor substrate and sintered to form an electrode. The conductive paste, by weight percentage, comprises: 65% to 80% conductive powder, 1% to 8% glass powder, 5% to 10% organic carrier, and the balance being additives. The glass powder contains lead. The additives include zirconium-containing compounds and gallium-containing compounds, wherein the gallium-containing compounds include gallium arsenide and the zirconium-containing compounds include zirconium dioxide, and the mass ratio of the zirconium-containing compounds to the gallium-containing compounds is 1:(2~4).

2. The method for preparing a battery cell according to claim 1, characterized in that, The additive is present in the conductive paste at a mass percentage of 1% to 2%.

3. The method for preparing the battery cell according to claim 1, characterized in that, The zirconium dioxide content in the conductive paste is 0.15% to 0.5% by mass.

4. The method for preparing a battery cell according to claim 1, characterized in that, The gallium-containing compound has a mass percentage content of 0.65% to 1.5% in the conductive paste.

5. The method for preparing a battery cell according to claim 1, characterized in that, The morphology of the additive includes at least one of spherical and near-spherical shapes, the median particle size of the zirconium-containing compound is 10 nm to 50 nm, and the median particle size of the gallium-containing compound is 0.5 μm to 3 μm.

6. The method for preparing a battery cell according to claim 1, characterized in that, The sintering is carried out in an inert gas atmosphere and includes: first heating from room temperature to 150℃~250℃, holding for 1s~3s, then heating to 300℃~450℃, holding for 1s~3s, then heating to 500℃~580℃, holding for 3s~5s, and then cooling to room temperature. The heating rate to 150℃~250℃ is denoted as S1℃ / s, the heating rate to 500℃~580℃ is denoted as S2℃ / s, and the cooling rate to room temperature is denoted as S3℃ / s, where S1≤S2<S3.

7. A battery cell, characterized in that, The battery cell is formed using the method for preparing a battery cell according to any one of claims 1 to 6, and the battery cell comprises: A semiconductor substrate, the semiconductor substrate including a first surface and a second surface disposed opposite to each other; A first electrode is electrically connected to a first surface of the semiconductor substrate; and / or A second electrode is formed electrically connected to the second surface of the semiconductor substrate.

8. A stacked battery, characterized in that, The stacked solar cell includes a perovskite top cell and a crystalline silicon bottom cell stacked sequentially, wherein the crystalline silicon bottom cell is a solar cell formed by the method of preparing the solar cell according to any one of claims 1 to 6 or a solar cell according to claim 7.

9. A photovoltaic module, characterized in that, The photovoltaic module includes: A battery string, wherein the battery string is formed by connecting multiple battery cells prepared by the method of any one of claims 1 to 6, or the battery cells of claim 7, or the stacked batteries of claim 8; An encapsulation layer covering the surface of the battery string, the material of the encapsulation layer comprising ethylene-vinyl acetate copolymer; A cover plate for covering the surface of the encapsulation layer away from the battery string.

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