Conductive paste and battery

Abstract

The application relates to a conductive paste and a battery. The components of the conductive paste include silver powder, glass powder, inorganic additives and an organic carrier; the glass powder includes 28wt%-100wt% of first glass powder, 0-36wt% of second glass powder and 0-36wt% of third glass powder in terms of mass percentage. The above conductive paste can wet the silver powder before the silver powder is sintered to form a crystal type by the first glass powder with specific components and a specific ratio, control the crystal type size and density of the silver powder and improve the silver conductive effect; meanwhile, the first glass powder can etch the conductive layer substrate and improve the ohmic contact. The second glass powder and the third glass powder are further added, the etching channel can be repaired while the melting of the silver powder is promoted and the etching rate of the substrate is controlled, the corrosion degree of the substrate is alleviated, the first glass powder and the second glass powder are prevented from excessively corroding the substrate; and the open circuit voltage is further improved and the carrier recombination loss is inhibited.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a conductive paste and a battery. Background Technology

[0002] TBC (Tunneling Oxide Passivated Contact) cells are a type of solar cell that combines TOPCon (Tunneling Oxide Passivated Contact) technology with IBC (Interdigitated Back Contact) technology. It integrates the excellent passivation contact performance of TOPCon cells with the advantage of unobstructed front-side contact in IBC cells, making it a highly efficient solar cell technology.

[0003] The working principle of TBC (Transient Carbon Cell) batteries is based on the photoelectric effect of semiconductors. When sunlight shines on the semiconductor material such as the silicon wafer of the battery, the energy of the photons is absorbed by the semiconductor, causing electrons in the valence band to jump to the conduction band, thus generating electron-hole pairs. In TBC batteries, due to their special structure, the generated electrons and holes move in opposite directions under the influence of an internal electric field. The anti-reflection layer and passivation layer on the front side help absorb light and reduce surface recombination, allowing for the effective separation of more photogenerated carriers. The passivation contact structure formed by the tunneling oxide layer and the doped polycrystalline silicon layer on the back side, along with the interdigitated back contact electrodes, efficiently collects and conducts electrons and holes. For example, electrons are led out through the N-type doped region of the back electrode, and holes are led out through the P-type doped region of the back electrode, then form a current through an external circuit, achieving photoelectric conversion.

[0004] The P-regions (P-type doped regions) and N-regions (N-type doped regions) on the back of the TBC battery are arranged alternately. The conductive layers of the N-regions and P-regions are formed by metallization co-sintering of conductive pastes. Among them, the conductive layer formed in the P-region often uses pure silver conductive paste and silver-aluminum conductive paste. However, after co-sintering, the P-region is prone to poor ohmic contact or large recombination loss, resulting in a high contact resistance. Summary of the Invention

[0005] Therefore, it is necessary to provide a conductive paste, wherein the conductive layer formed by the conductive paste has good ohmic contact with the substrate, thereby reducing contact resistance. Furthermore, a battery is provided.

[0006] The first aspect of this application provides a conductive paste, the components of which include silver powder, glass powder, inorganic additives and an organic carrier; the glass powder, by mass percentage, comprises 28wt%~100wt% of a first glass powder, 0~36wt% of a second glass powder and 0~36wt% of a third glass powder;

[0007] Based on molar percentage, the first glass powder comprises: TeO2 25 mol%–60 mol%, PbO 15 mol%–35 mol%, Bi2O3 1 mol%–15 mol%, B2O3 1 mol%–30 mol%, component a 1 mol%–50 mol%, and component b 0–20 mol%.

[0008] Based on molar percentage, the second glass powder comprises BaO 15 mol%–40 mol%, SiO2 10 mol%–60 mol%, B2O3 20 mol%–70 mol%, and component c 0–30 mol%.

[0009] Based on molar percentage content, the third glass powder comprises WO3 0.5mol%–15mol%, SiO2 10mol%–50mol%, B2O3 1mol%–15mol%, PbO 0–25mol%, Bi2O3 0%–15mol%, B2O3 0–15mol%, and component d 0–60mol%.

[0010] Wherein, component a includes at least one of the oxides, carbonates, and fluorides of Ba, Zn, P, Si, V, Ga, Ni, Al, W, and Fe; component b includes at least one of alkali metal oxides, alkali metal fluorides, and alkali metal carbonates; component c includes at least one of the oxides, carbonates, and fluorides of Pb, Zn, Al, and W; and component d includes at least one of the oxides, carbonates, and fluorides of Ti, Al, Cu, Zr, Ga, and Zn.

[0011] The aforementioned conductive paste contains silver powder, glass powder, inorganic additives, and an organic carrier. By controlling the specific components and proportions in the first glass powder, the glass transition temperature of the first glass powder is kept between 250°C and 400°C. In this way, during the sintering process, the glass powder can wet the silver powder before the silver powder forms a crystal structure, thereby better controlling the crystal size and density of the silver powder and improving the conductivity of silver. At the same time, the first glass powder can etch the conductive layer substrate, improving ohmic contact.

[0012] Furthermore, the addition of the second glass powder can further corrode the passivation layer while promoting the melting of the silver powder, thereby further improving the ohmic contact. Furthermore, the third glass powder has a high glass softening point, which can repair the etching channels near the sintering peak, alleviate the degree of substrate corrosion, and prevent excessive corrosion of the substrate by the first and second glass powders; thus further improving the open-circuit voltage and suppressing carrier recombination losses.

[0013] In some embodiments, the glass powder comprises, by weight percentage, 70wt% to 80wt% of the first glass powder, 18wt% to 22wt% of the second glass powder, and 4wt% to 6wt% of the third glass powder.

[0014] In some embodiments, the conductive paste satisfies at least one of the following conditions:

[0015] (1) In the composition of the first glass powder, the molar percentage of TeO2 is 26 mol%~46 mol%;

[0016] (2) In the composition of the first glass powder, the molar percentage of PbO is 22 mol%~35 mol%;

[0017] (3) In the composition of the first glass powder, the molar percentage of Bi2O3 is 4 mol%~12 mol%;

[0018] (4) In the composition of the first glass powder, the molar percentage of B2O3 is 0 mol%~8 mol%;

[0019] (5) In the composition of the first glass powder, the molar percentage of component a is 1 mol% to 20 mol%;

[0020] (6) In the composition of the first glass powder, the molar percentage of component b is 12 mol% to 25 mol.

[0021] In some embodiments, the conductive paste satisfies at least one of the following conditions:

[0022] (1) In the second glass powder, the molar percentage of BaO is 15 mol%~30 mol%;

[0023] (2) In the composition of the second glass powder, the molar percentage of SiO2 is 11 mol%~45 mol%;

[0024] (3) In the second glass powder, the molar percentage of component c is 5 mol% to 20 mol.

[0025] In some embodiments, the conductive paste satisfies at least one of the following conditions:

[0026] (1) In the third glass powder component, the molar percentage of WO3 is 2 mol%~10 mol%;

[0027] (2) The molar percentage of SiO2 in the third glass powder component is 15 mol% to 43 mol%;

[0028] (3) The molar percentage of B2O3 in the third glass powder component is 3 mol%~10 mol%

[0029] (4) The molar percentage of PbO in the third glass powder component is 0 mol% to 22 mol%;

[0030] (5) The molar percentage of Bi2O3 in the third glass powder component is 0 mol%~9 mol%;

[0031] (6) In the third glass powder component, the molar percentage of component d is 20 mol% to 56 mol%.

[0032] In some embodiments, the conductive paste comprises the following components by weight percentage:

[0033] The silver powder is 82wt% to 92wt%, the glass powder is 1.6wt% to 6.5wt%, the inorganic additive is 0.05wt% to 4wt%, and the organic carrier is 8wt% to 15wt%.

[0034] In some embodiments, the inorganic additive includes at least one of elemental silicon powder particles, silica powder, and tungsten oxide powder particles.

[0035] In some embodiments, the components of the organic carrier include solvents, resins, plasticizers, and additives;

[0036] The solvent is selected from at least one of alcohol ester twelve, alcohol ester sixteen, and diethylene glycol monobutyl ether;

[0037] The resin is selected from at least one of ethyl cellulose and rosin glycerol ester;

[0038] The plasticizer is selected from at least one of dimethyl phthalate, silicone oil and glycerin;

[0039] The additives include at least one of diluents, stearic acids, and polyamides.

[0040] In some embodiments, based on the total mass of the conductive paste, the organic carrier comprises: 5 wt% to 10 wt% of the solvent, 1.2 wt% to 2.6 wt% of the resin, 0.4 wt% to 1.5 wt% of the plasticizer, and 0.1 wt% to 0.9 wt% of the additives.

[0041] A second aspect of this application provides a battery, the battery comprising:

[0042] silicon substrate;

[0043] A tunneling oxide layer disposed on the back side of the silicon substrate;

[0044] P-type doped regions and N-type doped regions are disposed alternately on the tunneling oxide layer;

[0045] A first conductive layer disposed in the P-type doped region and a second conductive layer disposed in the N-type doped region;

[0046] The raw materials for preparing the first conductive layer include the conductive paste described in the first aspect. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the disclosed drawings without creative effort.

[0048] Figure 1 This is a cross-sectional structural diagram of a battery provided in one embodiment of this application.

[0049] Explanation of reference numerals in the attached figures:

[0050] 110. Silicon substrate; 120. Tunneling oxide layer; 130. P-type doped region; 140. N-type doped region; 150. First conductive layer; 160. Second conductive layer; 170. First passivation layer; 180. Second passivation layer. Detailed Implementation

[0051] To facilitate understanding of the present invention, a more comprehensive description is provided below, along with preferred embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. It should be understood that these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0053] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0054] The weights of the relevant components mentioned in the embodiments of this invention can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this invention is within the scope disclosed in the embodiments of this invention. Specifically, the weights mentioned in the embodiments of this invention can be well-known units of mass in the chemical industry, such as μg, mg, g, and kg.

[0055] One embodiment of this application provides a conductive paste, the components of which include silver powder, glass powder, inorganic additives and organic carrier; by mass percentage, the glass powder includes 28wt%~100wt% of first glass powder, 0~36wt% of second glass powder and 0~36wt% of third glass powder.

[0056] Based on molar percentage content, the components of the first glass powder include TeO2 25mol%–60mol%, PbO 15mol%–35mol%, Bi2O3 1mol%–15mol%, B2O3 0mol%–10mol%, component a 1mol%–50mol%, and component b 0–25mol%.

[0057] Based on molar percentage, the second glass powder comprises BaO 15mol%–40mol%, SiO2 10mol%–60mol%, B2O3 20mol%–70mol%, and component c 0–30mol%.

[0058] Based on molar percentage content, the components of the third glass powder include WO3 0.5mol%~15mol%, SiO2 10mol%~50mol%, B2O3 1mol%~15mol%, PbO 0~25mol%, Bi2O3 0%~15mol%, B2O3 0~15mol%, and component d 0~60mol.

[0059] Component a includes at least one of the oxides, carbonates, and fluorides of Zn, P, Si, Al, W, Mg, Ca, and Cu; component b includes at least one of the alkali metal oxides, alkali metal fluorides, and alkali metal carbonates; component c includes at least one of the oxides, carbonates, and fluorides of Pb, Al, and Ca; and component d includes at least one of the oxides, carbonates, and fluorides of Ti, Al, Cu, Zr, Ga, and Zn.

[0060] The aforementioned conductive paste contains silver powder, glass powder, inorganic additives, and an organic carrier. By controlling the specific components and proportions in the first glass powder, the glass transition temperature of the first glass powder is kept between 250°C and 400°C. In this way, during the sintering process, the glass powder can wet the silver powder before the silver powder forms a crystal structure, thereby better controlling the crystal size and density of the silver powder and improving the conductivity of silver. At the same time, the first glass powder can etch the silicon substrate and passivation layer, improving ohmic contact. In the first glass powder, PbO and Bi2O3 act on the substrate to etch it, improving ohmic contact. TeO2, B2O3, and component a can lower the melting and softening temperatures of the glass powder, giving it strong fluidity and a low softening point. This allows PbO and Bi2O3 to act on the substrate earlier and faster to etch it. At the same time, TeO2, B2O3, and component a have good wettability for metallic silver, which helps to open the passivation layer and allow the etching elements to better act on the silicon wafer. This enables control over the growth rate and size of silver microcrystals, achieving "small and dense" silver contact sites. Component b can further promote the melting of silver powder, improve the contact between silver powder and the silicon substrate, and enhance the ohmic contact effect.

[0061] Furthermore, the addition of a second glass powder can further corrode the passivation layer while promoting the melting of silver powder, thereby further improving ohmic contact.

[0062] The third glass powder has a higher glass softening point, which can repair the etching channels near the sintering peak, alleviate the degree of substrate corrosion, prevent excessive corrosion of the substrate by the first and second glass powders, and further improve the open circuit voltage and suppress carrier recombination loss.

[0063] As an example, the molar percentage content of TeO2 in the first glass powder can be 25 mol%, 26 mol%, 28 mol%, 30 mol%, 32 mol%, 35 mol%, 36 mol%, 38 mol%, 40 mol%, 44 mol%, 45 mol%, 48 mol%, 50 mol%, 55 mol%, 58 mol%, or 60 mol%, or a value within the range defined by any two of the above points as endpoints. Further, the molar percentage content of TeO2 in the first glass powder can be 25 mol% to 55 mol%. Even further, the molar percentage content of TeO2 can be 26 mol% to 46 mol%.

[0064] As an example, the molar percentage of PbO in the first glass powder can be 15 mol%, 18 mol%, 20 mol%, 22 mol%, 25 mol%, 26 mol%, 28 mol%, 30 mol%, 32 mol%, 33 mol%, or 35 mol%, or a value within the range defined by any two of the above points as endpoints. Further, the molar percentage of PbO in the first glass powder can be between 22 mol% and 35 mol%.

[0065] As an example, the molar percentage content of Bi2O3 in the first glass powder can be 1 mol%, 2 mol%, 3 mol%, 4 mol%, 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, 10 mol%, 11 mol%, 12 mol%, 13 mol%, 14 mol%, or 15 mol%, or a value within the range defined by any two of the above points as endpoints. Further, the molar percentage content of Bi2O3 in the first glass powder can be between 4 mol% and 12 mol%.

[0066] As an example, the molar percentage of B2O3 in the first glass powder can be 0, 1 mol%, 2 mol%, 3 mol%, 4 mol%, 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, or 10 mol%, or a value within the range defined by any two of the above points as endpoints. Further, the molar percentage of B2O3 in the first glass powder can be from 0 mol% to 8 mol%.

[0067] As an example, in the first glass powder, the molar percentage content of component a can be 1 mol%, 5 mol%, 10 mol%, 15 mol%, 20 mol%, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, or 50 mol%, or a value within the range formed by any two of the above points as endpoints. Further, in the first glass powder, the molar percentage content of component a can be between 1 mol% and 20 mol%.

[0068] In some embodiments, component a is selected from at least one of Zn, P, Si, Al, W, Mg, Ca, Cu, and their respective oxides and carbonates. Further, component a is selected from at least one of zinc oxide, phosphorus pentoxide, silicon dioxide, aluminum oxide, tungsten trioxide, magnesium oxide, calcium oxide, and copper oxide.

[0069] As an example, in the first glass powder, the molar percentage of component b can be 0, 1 mol%, 5 mol%, 6 mol%, 8 mol%, 10 mol%, 14 mol%, 15 mol%, 16 mol%, 18 mol%, 20 mol%, 22 mol%, 23 mol%, 24 mol%, or 25 mol%, or a value within the range defined by any two of the above points as endpoints. Further, in the first glass powder, the molar percentage of component b can be between 12 mol% and 25 mol%.

[0070] In some embodiments, component b includes at least one selected from lithium oxide, sodium oxide, potassium oxide, lithium carbonate, sodium carbonate, potassium carbonate, lithium fluoride, sodium fluoride, and potassium fluoride. Further, component b is selected from at least one selected from lithium carbonate, sodium carbonate, potassium carbonate, lithium oxide, sodium oxide, and potassium oxide.

[0071] In some embodiments, the first glass powder comprises: TeO2 26 mol%–46 mol%, PbO 22 mol%–35 mol%, Bi2O3 4 mol%–12 mol%, B2O3 0 mol%–8 mol%, component a 1 mol%–20 mol%, and component b 12–25 mol%.

[0072] As an example, in the composition of the second glass powder, the molar percentage content of BaO can be 15 mol%, 18 mol%, 20 mol%, 25 mol%, 28 mol%, 30 mol%, 32 mol%, 35 mol%, 38 mol%, or 40 mol%, or a value within the range formed by any two of the above points as endpoints. Further, in the second glass powder, the molar percentage content of BaO can be between 15 mol% and 30 mol%.

[0073] As an example, in the composition of the second glass powder, the molar percentage content of SiO2 can be 10 mol%, 12 mol%, 15 mol%, 20 mol%, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 50 mol%, or 60 mol%, or a value within the range defined by any two of the above points as endpoints. Further, in the second glass powder, the molar percentage content of SiO2 can be between 11 mol% and 45 mol%.

[0074] As an example, in the composition of the second glass powder, the molar percentage content of B2O3 can be 20 mol%, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, 50 mol%, 55 mol%, 60 mol%, 65 mol%, or 70 mol%, or a value within the range formed by any two of the above points as endpoints. Further, in the second glass powder, the molar percentage content of B2O3 can be 30 mol% to 50 mol%.

[0075] As an example, in the composition of the second glass powder, the molar percentage of component c can be 0, 5 mol%, 10 mol%, 12 mol%, 15 mol%, 18 mol%, 20 mol%, 22 mol%, 25 mol%, 26 mol%, 28 mol%, or 30 mol%, or a value within the range defined by any two of the above points as endpoints. Further, in the second glass powder, the molar percentage of component c can be between 5 mol% and 20 mol%.

[0076] In some embodiments, component c is selected from at least one of the corresponding oxides and carbonates of Pb, Al, and Ca. Further, component c is selected from at least one of PbO, Al₂O₃, and CaO.

[0077] In some embodiments, the second glass powder comprises: BaO 15mol%~30mol%, SiO2 11mol%~45mol%, B2O3 30mol%~50mol%, and component c 5mol%~20mol%.

[0078] As an example, in the composition of the third glass powder, the molar percentage content of WO3 can be 0.5 mol%, 1 mol%, 2 mol%, 5 mol%, 6 mol%, 8 mol%, 10 mol%, 12 mol%, or 15 mol%, or a value within the range formed by any two of the above points as endpoints. Further, in the third glass powder, the molar percentage content of WO3 can be 2 mol% to 10 mol%.

[0079] As an example, in the composition of the third glass powder, the molar percentage content of SiO2 can be 10 mol%, 15 mol%, 20 mol%, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, or 50 mol%, or a value within the range formed by any two of the above points as endpoints. Further, in the third glass powder, the molar percentage content of SiO2 can be between 15 mol% and 43 mol%.

[0080] As an example, in the composition of the third glass powder, the molar percentage content of B2O3 can be 1 mol%, 2 mol%, 5 mol%, 6 mol%, 8 mol%, 10 mol%, 12 mol%, or 15 mol%, or a value within the range defined by any two of the above points as endpoints. Further, in the third glass powder, the molar percentage content of B2O3 can be 3 mol% to 10 mol%.

[0081] As an example, in the composition of the third glass powder, the molar percentage of PbO can be 0, 1 mol%, 2 mol%, 5 mol%, 6 mol%, 8 mol%, 10 mol%, 12 mol%, 15 mol%, 18 mol%, 20 mol%, or 25 mol%, or a value within the range defined by any two of the above points as endpoints. Further, in the third glass powder, the molar percentage of PbO can be 0~22 mol%.

[0082] As an example, in the composition of the third glass powder, the molar percentage of Bi2O3 can be 0, 1 mol%, 2 mol%, 5 mol%, 6 mol%, 8 mol%, 10 mol%, 12 mol%, or 15 mol%, or a value within the range defined by any two of the above points as endpoints. Further, in the third glass powder, the molar percentage of Bi2O3 can be 0~9 mol%.

[0083] As an example, in the composition of the third glass powder, the molar percentage of component d can be 0, 5 mol%, 10 mol%, 15 mol%, 20 mol%, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, 50 mol%, 55 mol%, or 60 mol%, or a value within the range formed by any two of the above points as endpoints. Further, in the third glass powder, the molar percentage of component d can be 20 mol% to 56 mol%.

[0084] In some embodiments, the composition of the third glass powder is: WO3 2mol%~10mol%, SiO2 15mol%~43mol%, B2O3 3mol%~10mol%, PbO 0mol%~22mol%, Bi2O3 0mol%~9mol%, and component d 20mol%~56mol%.

[0085] As an example, the mass percentage of the first glass powder in the glass powder can be 28wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%, 95wt%, or 100wt%. It can be understood that when the content of the first glass powder in the glass powder is 100wt%, it means that the glass powder contains only the first glass powder and does not contain the second or third glass powder. Further, the mass percentage of the first glass powder in the glass powder can be a range of values ​​formed by using any two of the above points as endpoints. Further, the mass percentage of the first glass powder in the glass powder can be 60wt%~95wt%; more specifically, the mass percentage of the first glass powder in the glass powder can be 70wt%~90wt%; even more specifically, the mass percentage of the first glass powder in the glass powder can be 70wt%~80wt%.

[0086] As an example, the mass percentage of the second glass powder in the glass powder can be 0, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 22 wt%, 25 wt%, 28 wt%, 30 wt%, 35 wt%, or 36 wt%, or a value within the range formed by any two of the above points as endpoints. Further, the mass percentage of the second glass powder in the glass powder can be 2 wt% to 30 wt%. Further, the mass percentage of the second glass powder in the glass powder can be 15 wt% to 20 wt%. Further, the mass percentage of the second glass powder in the glass powder can be 18 wt% to 22 wt%.

[0087] As an example, the mass percentage of the third glass powder in the glass powder can be 0, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 22 wt%, 25 wt%, 28 wt%, 30 wt%, 35 wt%, or 36 wt%, or a value within the range formed by any two of the above points as endpoints. Further, the mass percentage of the third glass powder in the glass powder can be 2 wt% to 15 wt%. Further, the mass percentage of the third glass powder in the glass powder can be 4 wt% to 6 wt%.

[0088] In some embodiments, the glass powder comprises, by weight percentage, 70 wt% to 80 wt% of a first glass powder, 18 wt% to 22 wt% of a second glass powder, and 4 wt% to 6 wt% of a third glass powder. Furthermore, the three glass powder components work synergistically to etch the substrate while preventing excessive etching depth and reducing carrier recombination losses.

[0089] In some embodiments, the glass transition temperature (Tg) of the first glass powder is 250°C to 400°C.

[0090] In some embodiments, the glass transition temperature (Tg) of the second glass powder is 400°C to 550°C.

[0091] In some embodiments, the glass transition temperature (Tg) of the third glass powder is 500°C to 650°C.

[0092] In some embodiments, the conductive paste comprises the following components by weight percentage: 82wt% to 92wt% silver powder, 1.6wt% to 6.5wt% glass powder, 0.05wt% to 4wt% inorganic additives, and 8wt% to 15wt% organic carrier.

[0093] In some embodiments, the maximum particle size D100 of the silver powder is ≤ 5 μm. As an example, the maximum particle size D100 of the silver powder can be 5 μm, 4.5 μm, 4 μm, 3.5 μm, 3 μm, 2.5 μm, 2 μm, 1.5 μm, 1 μm, or 0.5 μm. Further, the maximum particle size D100 of the silver powder can be any other value within the above range. Further, the maximum particle size D100 of the silver powder is 2 μm to 4.5 μm.

[0094] In some embodiments, the maximum particle size D100 of the glass powder is ≤ 6 μm. As an example, the maximum particle size D100 of the glass powder can be 6 μm, 5.5 μm, 5 μm, 4.5 μm, 4 μm, 3.5 μm, 3 μm, 2.5 μm, 2 μm, 1.5 μm, 1 μm, or 0.5 μm. Further, the maximum particle size D100 of the glass powder can be any other value within the above range. Further, the maximum particle size D100 of the glass powder is 3 μm to 4.5 μm.

[0095] In some embodiments, the maximum particle size D100 of the inorganic additive is ≤ 5 μm. As an example, the maximum particle size D100 of the inorganic additive can be 5 μm, 4.5 μm, 4 μm, 3.5 μm, 3 μm, 2.5 μm, 2 μm, 1.5 μm, 1 μm, or 0.5 μm. Further, the maximum particle size D100 of the inorganic additive can be any other value within the above range. Further, the maximum particle size D100 of the inorganic additive is 0.1 μm to 2 μm.

[0096] In some embodiments, the inorganic additives include at least one of elemental silicon powder, silica powder, and tungsten oxide powder.

[0097] In some embodiments, the components of the organic carrier include solvents, resins, plasticizers, and additives.

[0098] In some embodiments, the solvent is selected from at least one of alcohol ester twelve, alcohol ester sixteen, and diethylene glycol monobutyl ether.

[0099] In some embodiments, the resin is selected from at least one of ethyl cellulose and rosin glycerol ester.

[0100] In some embodiments, the plasticizer is selected from at least one of dimethyl phthalate, silicone oil, and glycerin.

[0101] In some embodiments, the additives include at least one of diluents, stearic acids, and polyamides.

[0102] In some embodiments, the organic carrier comprises, by weight of the conductive paste, 5 wt% to 10 wt% of solvent, 1.2 wt% to 2.6 wt% of resin, 0.4 wt% to 1.5 wt% of plasticizer, and 0.1 wt% to 0.9 wt% of additives.

[0103] One embodiment of this application provides a method for preparing a conductive paste, comprising the following steps S1-S2:

[0104] Step S1: Weigh the first glass powder, the second glass powder, and the third glass powder according to the mass percentage ratio of the first glass powder, the second glass powder, and the third glass powder in the glass powder.

[0105] Step S2: Mix the first glass powder, the second glass powder, and the third glass powder with silver powder, inorganic additives, and organic carrier to obtain a conductive paste.

[0106] In some embodiments, the method for preparing conductive paste further includes the following steps:

[0107] Raw materials are prepared according to the component formulas of the first glass powder, the second glass powder, and the third glass powder, respectively. The raw materials are then melted and ground to obtain the first glass powder, the second glass powder, and the third glass powder, respectively.

[0108] In another embodiment of this application, a battery is provided, the battery comprising:

[0109] silicon substrate;

[0110] A tunneling oxide layer disposed on the back side of a silicon substrate;

[0111] P-type doped regions and N-type doped regions are disposed alternately on the tunneling oxide layer;

[0112] A first conductive layer disposed in a P-type doped region and a second conductive layer disposed in an N-type doped region;

[0113] The raw materials for preparing the first conductive layer include the aforementioned conductive paste.

[0114] In some embodiments, the raw materials for preparing the second conductive layer can be the conductive pastes commonly used in N-type doped regions, such as the conventional two-stage Pb-Bi-Si system paste used in TOPCon.

[0115] In some embodiments, the material of the tunneling oxide layer is poly-Si or ultrathin SiO2, etc.

[0116] See Figure 1 In some embodiments, the battery 100 includes: a silicon substrate 110, a tunneling oxide layer 120 disposed on the back side of the silicon substrate 110, a P-type doped region 130 and an N-type doped region 140 disposed on the tunneling oxide layer 120 and alternately disposed therebetween, and a first conductive layer 150 disposed on the P-type doped region 130 and a second conductive layer 160 disposed on the N-type doped region 140.

[0117] Furthermore, the tunneling oxide layer 120 disposed on the back side of the silicon substrate 110 has several sub-regions, with adjacent tunneling oxide sub-regions spaced apart. Even further, each tunneling oxide sub-region has a P-type doped region 130 or an N-type doped region 140, with adjacent tunneling oxide sub-regions having different types of doped regions; this allows for alternating spacing of the P-type doped region 130 and the N-type doped region 140 on the tunneling oxide layer 120. As an example, one tunneling oxide sub-region has a P-type doped region 130, and an adjacent tunneling oxide sub-region has an N-type doped region 140.

[0118] Furthermore, the battery 100 also includes a first passivation layer 170 disposed on the silicon substrate 110. Even further, the first passivation layer 170 is also disposed on the surface of the P-type doped region 130 that is not in contact with the first conductive layer 150. Even further, the first passivation layer 170 is also disposed on the surface of the N-type doped region 140 that is not in contact with the second conductive layer 160.

[0119] In some embodiments, the battery 100 described above has a second passivation layer 180 disposed on the front side of the silicon substrate 110.

[0120] In some embodiments, the materials of the first passivation layer 170 and the second passivation layer 180 are independently selected from silicon nitride, silicon oxynitride, silicon oxide, or aluminum oxide, respectively.

[0121] In some embodiments, the battery described above includes a TBC battery.

[0122] To make the objectives, technical solutions, and advantages of this invention clearer and more concise, the invention is described using the following specific embodiments, but the invention is by no means limited to these embodiments. The embodiments described below are merely preferred embodiments of the invention and can be used to describe the invention, but should not be construed as limiting the scope of the invention. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the protection scope of this invention.

[0123] To better illustrate the present invention, the following embodiments are provided for further explanation. The specific embodiments are as follows.

[0124] Preparation of glass powder:

[0125] According to the glass powder composition formulas in Tables 1-3, the raw materials were weighed, mixed evenly, and placed in a corundum crucible. The mixture was then melted at 900℃-1600℃ for 30-90 minutes. After cooling, glass material was obtained. The glass material was ball-milled and sieved to obtain first, second, and third glass powders with a maximum particle size ≤6μm. Specifically, the composition formulas of the first glass powder are shown in Table 1, the second glass powder in Table 2, and the third glass powder in Table 3.

[0126] Table 1. Component formulation of the first glass powder

[0127]

[0128] Table 2. Component formulation of the second glass powder

[0129]

[0130] Table 3 Formulation of the third glass powder component

[0131]

[0132] Examples of conductive paste and solar cell fabrication:

[0133] The grid paste used in the various embodiments and comparative examples of this application for preparing battery cells is the conventional Pb-Cu-Mn main grid system paste for TOPCon batteries; the N-region conductive paste is the conventional two-stage Pb-Bi-Si system paste for TOPCon batteries.

[0134] The solvents used in the various embodiments and comparative examples of this application are hexadecyl alcohol ester and diethylene glycol monobutyl ether in a mass ratio of 40:60; the resin is rosin glycerol ester; the plasticizer is dimethyl phthalate; and the diluent is terpineol.

[0135] Example 1

[0136] (1) According to the formula of conductive paste: 88.6wt% silver powder, 2.3wt% first glass powder P2, 6wt% solvent, 1.9wt% resin, 1wt% plasticizer, 0.1wt% diluent and 0.1wt% inorganic additive fumed silica, weigh the raw materials; premix the raw materials except diluent in a planetary mixer to form a mixed paste; then grind the mixed paste 6 times on a ceramic three-roll mill; test the fineness of the mixed paste with a scraper fineness meter; control the fineness of the paste to <10μm, add 0.1wt% diluent to obtain conductive paste.

[0137] (2) See Figure 1 A TBC battery was prepared. Using an automatic printing machine, the main grid paste was first printed on the back side of the TBC battery blue film (which includes a silicon substrate 110, a second passivation layer 180 disposed on the front side of the silicon substrate 110, a plurality of tunneling oxide sub-regions disposed at intervals on the back side of the silicon substrate 110, P-type doped regions 130 and N-type doped regions 140 alternately disposed on the surfaces of adjacent tunneling oxide sub-regions, and a first passivation layer 170 on the silicon substrate 110 and covering the entire surfaces of the P-type doped regions 130 and N-type doped regions 140), and then dried; N-region conductive paste was printed in the N-region and dried; conductive paste prepared in step (1) above was printed in the P-region; and then sintered in a sintering furnace to obtain the battery cell.

[0138] Examples 2-11 and Comparative Examples 1-2

[0139] The preparation methods of Examples 2-11 and Comparative Examples 1-2 are basically the same as those of Example 1, except that the formulation of the conductive paste is different. Specifically, the formulation of the conductive paste prepared by each example and comparative example is shown in Table 4.

[0140] Table 4

[0141]

[0142] The commercially available glass powder used in Comparative Example 1 mainly consists of PbO 30mol%, SiO2 8mol%, Al2O3 23mol%, Fe2O3 9mol%, and B2O3 30mol%.

[0143] Performance testing

[0144] The photoelectric conversion efficiency (Eta), open-circuit voltage (Uoc), short-circuit current (Isc), and fill factor (FF) of the solar cells prepared in each embodiment and comparative example were tested according to the method specified in GB / T 6495.4-1996. Then, using the performance data of the solar cell prepared in Comparative Example 1 as a benchmark, the differences between the performance data of each solar cell prepared in Examples 1-11 and Comparative Example 2 and the performance data of the solar cell in Comparative Example 1 were calculated. The specific calculation results are shown in Table 5.

[0145] Table 5

[0146]

[0147] As can be seen from the data in Table 5, compared with the solar cell prepared using conventional P-region conductive paste in Comparative Example 1, the solar cells obtained in Examples 1 to 11 using conductive paste with specific components of this application in the P-region show significantly improved photoelectric conversion efficiency, open-circuit voltage, and fill factor. This indicates that the conductive paste provided by this application reduces the recombination loss rate in the P-region of the TBC cell and greatly improves the ohmic contact effect. Comparative Example 1 uses conventional TOPCon cell P-region paste, which contains a large amount of Pb and B elements, leading to intensified etching performance, poor overall fluidity of its glass system, poor silver microcrystal state, and poor ohmic contact effect.

[0148] In Comparative Example 2, although the conductive paste used had an increased content of Bi oxide, the low Pb content resulted in weak corrosion resistance, preventing the formation of good conductive channels and hindering the improvement of the fill factor. Consequently, the solar cell prepared in Comparative Example 2 exhibited poor ohmic contact and its electrical performance was inferior to that of Example 1.

[0149] It is evident that the conductive paste obtained by the present application through the synergistic interaction of first glass powder, silver powder, inorganic additives and organic carrier in a specific composition ratio can improve the ohmic contact in the battery cell, increase the open circuit voltage and suppress carrier recombination loss.

[0150] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0151] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A conductive paste, characterized in that, Its components include silver powder, glass powder, inorganic additives and organic carrier; by mass percentage, the glass powder includes 28wt% to 95wt% of first glass powder, 2wt% to 36wt% of second glass powder and 0wt% to 36wt% of third glass powder, or the glass powder includes 28wt% to 95wt% of first glass powder, 0wt% to 36wt% of second glass powder and 2wt% to 36wt% of third glass powder; Based on molar percentage content, the first glass powder comprises TeO2 25mol%–60mol%, PbO 15mol%–35mol%, Bi2O3 1mol%–15mol%, B2O3 0mol%–10mol%, component a 1mol%–50mol%, and component b 0–25mol%. Based on molar percentage content, the second glass powder comprises BaO 15mol%–40mol%, SiO2 10mol%–60mol%, B2O3 20mol%–70mol%, and component c 0–30mol%. According to the molar percentage content, the components of the third glass powder include WO3 0.5mol% to 15mol%, SiO2 10mol% to 50mol%, B2O3 1mol% to 15mol%, PbO 0 to 25mol%, Bi2O3 0% to 15mol%, and component d 0 to 60mol%. Wherein, component a includes at least one of the oxides, carbonates, and fluorides of Zn, P, Si, Al, W, Mg, Ca, and Cu; component b includes at least one of alkali metal oxides, alkali metal fluorides, and alkali metal carbonates; component c includes at least one of the oxides, carbonates, and fluorides of Pb, Al, and Ca; and component d includes at least one of the oxides, carbonates, and fluorides of Ti, Al, Cu, Zr, Ga, and Zn.

2. The conductive paste as described in claim 1, characterized in that, The glass powder comprises, by weight percentage, 28 wt% to 95 wt% of the first glass powder, 2 wt% to 36 wt% of the second glass powder, and 2 wt% to 36 wt% of the third glass powder.

3. The conductive paste as described in claim 2, characterized in that, The glass powder comprises, by weight percentage, 70 wt% to 80 wt% of the first glass powder, 18 wt% to 22 wt% of the second glass powder, and 4 wt% to 6 wt% of the third glass powder.

4. The conductive paste as described in claim 1, characterized in that, The conductive paste satisfies at least one of the following conditions: (1) In the composition of the first glass powder, the molar percentage of TeO2 is 26 mol% to 46 mol%. (2) In the composition of the first glass powder, the molar percentage of PbO is 22 mol% to 35 mol%. (3) In the composition of the first glass powder, the molar percentage of Bi2O3 is 4 mol% to 12 mol%. (4) In the composition of the first glass powder, the molar percentage of B2O3 is 0 mol% to 8 mol%. (5) In the composition of the first glass powder, the molar percentage of component a is 1 mol% to 20 mol%. (6) In the composition of the first glass powder, the molar percentage of component b is 12 mol% to 25 mol%.

5. The conductive paste as described in claim 1, characterized in that, The conductive paste satisfies at least one of the following conditions: (1) In the second glass powder, the molar percentage of BaO is 15 mol% to 30 mol%. (2) In the composition of the second glass powder, the molar percentage of SiO2 is 11 mol% to 45 mol%. (3) In the second glass powder, the molar percentage of component c is 5 mol% to 20 mol%.

6. The conductive paste as described in claim 1, characterized in that, The conductive paste satisfies at least one of the following conditions: (1) In the third glass powder component, the molar percentage of WO3 is 2 mol% to 10 mol%. (2) The molar percentage of SiO2 in the third glass powder component is 15 mol% to 43 mol%. (3) The molar percentage of B2O3 in the third glass powder component is 3 mol% to 10 mol%. (4) In the third glass powder component, the molar percentage of PbO is 0 mol% to 22 mol%. (5) In the third glass powder component, the molar percentage of Bi2O3 is 0 mol% to 9 mol%. (6) In the third glass powder component, the molar percentage of component d is 20 mol% to 56 mol%.

7. The conductive paste according to any one of claims 1 to 6, characterized in that, The conductive paste satisfies at least one of the following conditions: (1) The maximum particle size of the silver powder, D100, is ≤5μm; (2) The maximum particle size of the glass powder, D100, is ≤6μm; (3) The maximum particle size of the inorganic additive, D100, is ≤5μm.

8. The conductive paste according to any one of claims 1 to 6, characterized in that, The inorganic additives include at least one of elemental silicon powder particles, silica powder, and tungsten oxide powder particles.

9. The conductive paste according to any one of claims 1 to 6, characterized in that, The components of the organic carrier include solvent, resin, plasticizer, and additives; The solvent is selected from at least one of alcohol ester twelve, alcohol ester sixteen, and diethylene glycol monobutyl ether; The resin is selected from at least one of ethyl cellulose and rosin glycerol ester; The plasticizer is selected from at least one of dimethyl phthalate, silicone oil and glycerin; The additives include at least one of diluents, stearic acids, and polyamides.

10. The conductive paste as described in claim 9, characterized in that, Based on the total mass of the conductive paste, the organic carrier comprises: 5 wt% to 10 wt% of the solvent, 1.2 wt% to 2.6 wt% of the resin, 0.4 wt% to 1.5 wt% of the plasticizer, and 0.1 wt% to 0.9 wt% of the additives.

11. A battery, characterized in that, The battery includes: silicon substrate; A tunneling oxide layer disposed on the back side of the silicon substrate; P-type doped regions and N-type doped regions are disposed alternately on the tunneling oxide layer; A first conductive layer disposed in the P-type doped region and a second conductive layer disposed in the N-type doped region; The raw materials for preparing the first conductive layer include the conductive paste as described in any one of claims 1 to 10.

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