Conductive paste and battery

Abstract

The invention relates to conductive paste and a battery. The conductive paste comprises the following components: silver powder, glass powder, an inorganic additive and an organic carrier, the glass powder comprises the following components in percentage by mass: 28 to 100 weight percent of first glass powder, 0 to 36 weight percent of second glass powder and 0 to 36 weight percent of third glass powder. According to the conductive paste, the silver powder is wetted and the size and density of the crystal form of the silver powder are controlled through the first glass powder with specific components and proportions before the silver powder is sintered to form the crystal form, so that the conductive effect of silver is improved; and meanwhile, the first glass powder can etch the conductive layer substrate, so that the ohmic contact is improved. Furthermore, second glass powder and third glass powder are added, so that an etching channel can be repaired, the corrosion degree of the substrate can be relieved and excessive corrosion of the first glass powder and the second glass powder to the substrate can be prevented while melting of the silver powder is promoted and the etching rate of the substrate is controlled; therefore, the open-circuit voltage is further improved, and the recombination loss of carriers is inhibited.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a conductive paste and a battery. Background Art

[0002] TBC cell is a solar cell that combines TOPCon (tunneling oxide passivation contact) technology and IBC (interdigitated back contact) technology. It combines the excellent passivation contact performance of TOPCon cells and the advantage of unobstructed front side of IBC cells, and is a high-efficiency solar cell technology.

[0003] The working basis of TBC cells is the photoelectric effect of semiconductors. When sunlight shines on semiconductor materials such as silicon wafers of the cell, the energy of the photons is absorbed by the semiconductor, causing the electrons in the valence band to jump to the conduction band, thereby generating electron-hole pairs. In TBC cells, due to their special structure, the generated electrons and holes will move in opposite directions under the action of the internal electric field. Among them, the anti-reflection layer and passivation layer on the front side help absorb light and reduce surface recombination, so that more photogenerated carriers can be effectively separated. The passivation contact structure formed by the tunneling oxide layer and the doped polysilicon layer on the back side, as well as the interdigitated back contact electrode, can efficiently collect and conduct electrons and holes. For example, electrons are extracted through the back electrode of the N-type doped area, and holes are extracted through the back electrode of the P-type doped area, and then a current is formed through the external circuit to achieve photoelectric conversion.

[0004] The P region (i.e., P-type doped region) and N region (i.e., N-type doped region) on the back of the TBC battery are arranged alternately, and the conductive layers of the N region and the P region are formed by metallization co-sintering of the conductive paste. Among them, the conductive layer formed in the P region often uses pure silver conductive paste and silver-aluminum conductive paste, but after co-sintering, the paste makes it easy for the P region to have poor ohmic contact or large composite loss, resulting in a large contact resistance. Summary of the invention

[0005] Based on this, 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 the contact resistance. Furthermore, a battery is provided.

[0006] The first aspect of the present application provides a conductive paste, the components of which include silver powder, glass powder, inorganic additives and organic carriers; the glass powder includes 28wt% to 100wt% of the first glass powder, 0 to 36wt% of the second glass powder and 0 to 36wt% of the third glass powder in terms of mass percentage;

[0007] In terms of molar percentage, the components of the first glass powder include TeO2 25mol% to 60mol%, PbO 15mol% to 35mol%, Bi2O3 1mol% to 15mol%, B2O3 1mol% to 30mol%, component a 1mol% to 50mol% and component b 0 to 20mol%;

[0008] In terms of molar percentage, the components of the second glass powder include BaO 15mol% to 40mol%, SiO2 10mol% to 60mol%, B2O3 20mol% to 70mol% and component c 0 to 30mol%;

[0009] In terms of molar percentage, 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%;

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

[0011] The above-mentioned conductive paste contains silver powder, glass powder, inorganic additives and organic carriers. By controlling the specific components and ratios in the first glass powder, the glass transition temperature of the first glass powder is between 250°C and 400°C. In this way, during the sintering process, the glass powder can wet the glass powder before the silver powder forms a crystal, thereby better controlling the crystal size and density of the silver powder and improving the conductive effect of silver; at the same time, the first glass powder can etch the conductive layer substrate to improve the 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, further improving the ohmic contact. Furthermore, the third glass powder has a higher glass softening point, which can repair the etching channel near the sintering peak, alleviate the corrosion degree of the substrate, and prevent the first glass powder and the second glass powder from excessively corroding the substrate; thereby further improving the open circuit voltage and suppressing the recombination loss of carriers.

[0013] In some embodiments, the glass powder includes, 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.

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

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

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

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

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

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

[0020] (6) Among the components of the first glass powder, the molar percentage of the 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 components of the second glass powder, the molar percentage of BaO is 15 mol% to 30 mol%;

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

[0024] (3) Among the components of the second glass powder, the molar percentage of the 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 2mol% to 10mol%;

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

[0028] (3) In the third glass powder component, the molar percentage of B2O3 is 3 mol% to 10 mol%;

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

[0030] (5) In the third glass powder component, the molar percentage of Bi2O3 is 0mol% to 9mol%;

[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 includes the following components by weight percentage:

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

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

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

[0036] The solvent is selected from at least one of alcohol ester dodecahydrate, alcohol ester hexadecene 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 auxiliary agent includes at least one of a diluent, stearic acid and polyamide.

[0040] In some embodiments, based on the total mass of the conductive paste, the components of the organic vehicle include: 5wt%~10wt% of the solvent, 1.2wt%~2.6wt% of the resin, 0.4wt%~1.5wt% of the plasticizer and 0.1wt%~0.9wt% of the auxiliary agent.

[0041] A second aspect of the present 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 on the tunnel oxide layer and are alternately disposed at intervals;

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

[0046] The raw material for preparing the first conductive layer includes the conductive paste described in the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are merely embodiments of the present application, and ordinary technicians in this field can obtain other drawings based on the disclosed drawings without paying any creative work.

[0048] Figure 1 A schematic diagram of a cross-sectional structure of a battery provided in one embodiment of the present application.

[0049] Description of reference numerals:

[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 DESCRIPTION

[0051] In order to facilitate the understanding of the present invention, the present invention is described more comprehensively below. And preferred embodiments of the present invention are given. 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 the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

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

[0054] The weight of the relevant components mentioned in the description of the embodiments of the present invention may not only refer to the specific content of each component, but also indicate the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the description of the embodiments of the present invention, it is within the scope disclosed in the description of the embodiments of the present invention. Specifically, the weight described in the description of the embodiments of the present invention may be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0055] In one embodiment of the present application, a conductive paste is provided, whose components include silver powder, glass powder, inorganic additives and organic carriers; in terms of mass percentage, the glass powder includes 28wt%~100wt% of the first glass powder, 0~36wt% of the second glass powder and 0~36wt% of the third glass powder.

[0056] In terms of molar percentage, the components of the first glass powder include TeO2 25mol% to 60mol%, PbO 15mol% to 35mol%, Bi2O3 1mol% to 15mol%, B2O3 0mol% to 10mol%, component a 1mol% to 50mol% and component b 0 to 25mol%;

[0057] In terms of molar percentage, the components of the second glass powder include BaO 15mol% to 40mol%, SiO2 10mol% to 60mol%, B2O3 20mol% to 70mol% and component c 0 to 30mol%;

[0058] In terms of molar percentage, 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] Among them, component a includes at least one of the oxides, carbonates and fluorides corresponding to 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 corresponding to Pb, Al and Ca; component d includes at least one of the oxides, carbonates and fluorides corresponding to Ti, Al, Cu, Zr, Ga and Zn.

[0060] The above-mentioned conductive paste contains silver powder, glass powder, inorganic additives and organic carriers. By controlling the specific components and ratios in the first glass powder, the glass transition temperature of the first glass powder is 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, thereby better controlling the crystal size and density of the silver powder and improving the conductive effect of silver; at the same time, the first glass powder can etch the silicon substrate and the passivation layer to improve the ohmic contact. Among them, PbO and Bi2O3 in the first glass powder act on the substrate to corrode the substrate, thereby improving the ohmic contact; TeO2, B2O3 and component a can reduce the melting temperature and softening temperature of the glass powder, giving the glass powder stronger fluidity and lower softening point characteristics; in this way, PbO and Bi2O3 can act on the substrate to corrode the substrate earlier and faster; at the same time, TeO2, B2O3 and component a have good wettability to metallic silver, which is conducive to opening the passivation layer so that the etching elements can better act on the silicon wafer, and can control the growth rate and scale of silver microcrystals to achieve "small and dense" silver contact sites; component b can further promote the melting of silver powder, enhance the contact between silver powder and silicon substrate, and improve the ohmic contact effect.

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

[0062] The third glass powder has a higher glass softening point, and can repair the etching channel near the sintering peak, alleviate the corrosion degree of the substrate, prevent the first glass powder and the second glass powder from excessively corroding the substrate, and further increase the open circuit voltage and inhibit the recombination loss of carriers.

[0063] As an example, in the first glass powder, the molar percentage of TeO2 may be 25mol%, 26mol%, 28mol%, 30mol%, 32mol%, 35mol%, 36mol%, 38mol%, 40mol%, 44mol%, 45mol%, 48mol%, 50mol%, 55mol%, 58mol% or 60mol%, or a value within a range consisting of any two of the above point values ​​as end values. Further, in the first glass powder, the molar percentage of TeO2 may be 25mol% to 55mol%. Further, the molar percentage of TeO2 may be 26mol% to 46mol%.

[0064] As an example, in the first glass powder, the molar percentage of PbO may 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 a range consisting of any two of the above point values ​​as end values. Further, in the first glass powder, the molar percentage of PbO may be 22 mol% to 35 mol%.

[0065] As an example, in the first glass powder, the molar percentage of Bi2O3 may 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 a range consisting of any two of the above point values ​​as end values. Further, in the first glass powder, the molar percentage of Bi2O3 may be 4 mol% to 12 mol%.

[0066] As an example, in the first glass powder, the molar percentage of B2O3 can be 0, 1mol%, 2mol%, 3mol%, 4mol%, 5mol%, 6mol%, 7mol%, 8mol%, 9mol% or 10mol%, or a value within a range consisting of any two of the above point values ​​as end values. Further, in the first glass powder, the molar percentage of B2O3 can be 0mol%~8mol%.

[0067] As an example, in the first glass powder, the molar percentage of component a may 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 a range consisting of any two of the above point values ​​as end values. Further, in the first glass powder, the molar percentage of component a may be 1 mol% to 20 mol%.

[0068] In some embodiments, component a is selected from at least one of oxides and carbonates corresponding to Zn, P, Si, Al, W, Mg, Ca, Cu, and Si. Further, component a is selected from at least one of zinc oxide, phosphorus pentoxide, silicon dioxide, aluminum trioxide, 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 a range consisting of any two of the above point values ​​as end values. Further, in the first glass powder, the molar percentage of component b can be 12 mol% to 25 mol%.

[0070] In some embodiments, component b includes at least one of 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 of lithium carbonate, sodium carbonate, potassium carbonate, lithium oxide, sodium oxide and potassium oxide.

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

[0072] As an example, in the components of the second glass powder, the molar percentage of BaO can be 15mol%, 18mol%, 20mol%, 25mol%, 28mol%, 30mol%, 32mol%, 35mol%, 38mol% or 40mol%, or a value within the range consisting of any two of the above point values ​​as end values. Further, in the second glass powder, the molar percentage of BaO can be 15mol% to 30mol%.

[0073] As an example, in the components of the second glass powder, the molar percentage of SiO2 can be 10mol%, 12mol%, 15mol%, 20mol%, 25mol%, 30mol%, 35mol%, 40mol%, 50mol% or 60mol%, or a value within the range formed by any two of the above point values ​​as end values. Further, in the second glass powder, the molar percentage of SiO2 can be 11mol%~45mol%.

[0074] As an example, in the components of the second glass powder, the molar percentage of B2O3 may be 20mol%, 25mol%, 30mol%, 35mol%, 40mol%, 45mol%, 50mol%, 55mol%, 60mol%, 65mol% or 70mol%, or a value within a range consisting of any two of the above point values ​​as end values. Further, in the second glass powder, the molar percentage of B2O3 may be 30mol% to 50mol%.

[0075] As an example, in the components of the second glass powder, the molar percentage of component c can be 0, 5mol%, 10mol%, 12mol%, 15mol%, 18mol%, 20mol%, 22mol%, 25mol%, 26mol%, 28mol% or 30mol%, or a value within the range formed by any two of the above point values ​​as end values. Further, in the second glass powder, the molar percentage of component c can be 5mol%~20mol%.

[0076] In some embodiments, component c is selected from at least one of oxides and carbonates corresponding to 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 has components of: BaO 15 mol%-30 mol%, SiO2 11 mol%-45 mol%, B2O3 30 mol%-50, and component c 5 mol%-20 mol%.

[0078] As an example, in the components of the third glass powder, the molar percentage of WO3 can be 0.5mol%, 1mol%, 2mol%, 5mol%, 6mol%, 8mol%, 10mol%, 12mol% or 15mol%, or a value within the range formed by any two of the above point values ​​as end values. Further, in the third glass powder, the molar percentage of WO3 can be 2mol%~10mol%.

[0079] As an example, in the components of the third glass powder, the molar percentage of SiO2 can be 10mol%, 15mol%, 20mol%, 25mol%, 30mol%, 35mol%, 40mol%, 45mol% or 50mol%, or a value within a range consisting of any two of the above point values ​​as end values. Further, in the third glass powder, the molar percentage of SiO2 can be 15mol%~43mol%.

[0080] As an example, in the components of the third glass powder, the molar percentage of B2O3 may be 1 mol%, 2 mol%, 5 mol%, 6 mol%, 8 mol%, 10 mol%, 12 mol% or 15 mol%, or a value within a range consisting of any two of the above point values ​​as end values. Further, in the third glass powder, the molar percentage of B2O3 may be 3 mol% to 10 mol%.

[0081] As an example, in the components 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 a range consisting of any two of the above point values ​​as end values. Further, in the third glass powder, the molar percentage of PbO can be 0-22 mol%.

[0082] As an example, in the components of the third glass powder, the molar percentage of Bi2O3 can be 0, 1mol%, 2mol%, 5mol%, 6mol%, 8mol%, 10mol%, 12mol% or 15mol%, or a value within the range formed by any two of the above point values ​​as end values. Further, in the third glass powder, the molar percentage of Bi2O3 can be 0-9mol%.

[0083] As an example, in the components of the third glass powder, the molar percentage of component d can be 0, 5mol%, 10mol%, 15mol%, 20mol%, 25mol%, 30mol%, 35mol%, 40mol%, 45mol%, 50mol%, 55mol% or 60mol%, or a value within the range consisting of any two of the above point values ​​as end values. Further, in the third glass powder, the molar percentage of component d can be 20mol%~56mol%.

[0084] In some embodiments, the third glass powder has components of 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 only contains the first glass powder, but does not contain the second glass powder and the third glass powder. Further, the mass percentage of the first glass powder in the glass powder can be a range value composed of any two of the above point values ​​as end values. Further, the mass percentage of the first glass powder in the glass powder can be 60wt%~95wt%; further, the mass percentage of the first glass powder in the glass powder can be 70wt%~90wt%; further, 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, 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, 22wt%, 25wt%, 28wt%, 30wt%, 35wt% or 36wt%, or a value within the range formed by any two of the above point values ​​as end values. Further, the mass percentage of the second glass powder in the glass powder can be 2wt%~30wt%. Further, the mass percentage of the second glass powder in the glass powder can be 15wt%~20wt%. Further, the mass percentage of the second glass powder in the glass powder can be 18wt%~22wt%.

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

[0088] In some embodiments, the glass powder includes 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, by weight percentage. The three glass powder components cooperate with each other to etch the substrate, while preventing the etching from being too deep and reducing the recombination loss of carriers.

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

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

[0091] In some embodiments, the third glass frit has a glass transition temperature Tg of 500°C to 650°C.

[0092] In some embodiments, the conductive paste includes the following components, calculated by weight percentage: 82 wt% to 92 wt% silver powder, 1.6 wt% to 6.5 wt% glass powder, 0.05 wt% to 4 wt% inorganic additives, and 8 wt% to 15 wt% 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 may 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 may 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 additive includes at least one of elemental silicon powder, silicon dioxide powder, and tungsten oxide powder.

[0097] In some embodiments, the components of the organic vehicle include a solvent, a resin, a plasticizer, and an additive.

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

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

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

[0101] In some embodiments, the auxiliary agent includes at least one of a diluent, stearic acid, and polyamide.

[0102] In some embodiments, based on the total mass of the conductive paste, the components of the organic vehicle include: 5 wt % to 10 wt % of a solvent, 1.2 wt % to 2.6 wt % of a resin, 0.4 wt % to 1.5 wt % of a plasticizer, and 0.1 wt % to 0.9 wt % of an auxiliary agent.

[0103] In one embodiment of the present application, a method for preparing a conductive paste is provided, comprising the following steps S1-S2:

[0104] Step S1, weighing the first glass powder, the second glass powder and the third glass powder respectively 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 the conductive paste further comprises the following steps:

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

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

[0109] Silicon substrate;

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

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

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

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

[0114] In some embodiments, the second conductive layer may be prepared using a conductive paste commonly used in N-type doping regions, such as a conventional two-layer Pb-Bi-Si system paste used in TOPCon.

[0115] In some embodiments, the material of the tunnel oxide layer is poly-Si or ultra-thin SiO 2 .

[0116] See also 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 at intervals, and a first conductive layer 150 disposed in the P-type doped region 130 and a second conductive layer 160 disposed in the N-type doped region 140.

[0117] Furthermore, the tunneling oxide layer 120 disposed on the back side of the silicon substrate 110 has a plurality of sub-regions, which are arranged at intervals between two adjacent tunneling oxide layer sub-regions. Furthermore, each tunneling oxide layer sub-region is provided with a P-type doping region 130 or an N-type doping region 140, and the doping region types disposed on two adjacent tunneling oxide layer sub-regions are different; thus, the P-type doping region 130 and the N-type doping region 140 can be alternately disposed at intervals on the tunneling oxide layer 120. As an example, a P-type doping region 130 is disposed on one tunneling oxide layer sub-region, and an N-type doping region 140 is disposed on another tunneling oxide layer sub-region adjacent thereto.

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

[0119] In some embodiments, in the above battery 100 , a second passivation layer 180 is disposed on the front surface 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, aluminum oxide, etc.

[0121] In some embodiments, the above-mentioned battery comprises a TBC battery.

[0122] In order to make the purpose, technical solutions and advantages of the present invention more concise and clear, the present invention is described with the following specific embodiments, but the present invention is by no means limited to these embodiments. The embodiments described below are only preferred embodiments of the present invention, which can be used to describe the present invention and cannot be understood as limiting the scope of the present invention. It should be pointed out that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0123] In order to better illustrate the present invention, the present invention is further described below in conjunction with the embodiments. The following are specific embodiments.

[0124] Preparation of glass powder:

[0125] According to the component formula of the glass powder in Table 1 to Table 3, the raw materials are weighed respectively, and then the corresponding raw materials are mixed evenly, placed in a corundum crucible, and melted at 900°C to 1600°C for 30min to 90min; after cooling, glass material is obtained; the glass material is ball-milled and sieved to obtain the first glass powder, the second glass powder and the third glass powder with a maximum particle size of ≤6μm. Specifically, the component formula of the first glass powder is shown in Table 1, the component formula of the second glass powder is shown in Table 2, and the component formula of the third glass powder is shown in Table 3.

[0126] Table 1 Composition formula of the first glass powder

[0127]

[0128] Table 2 Composition formula of the second glass powder

[0129]

[0130] Table 3 Third glass powder component formula

[0131]

[0132] Example of preparation of conductive paste and battery cell:

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

[0134] The solvent used in each embodiment and comparative example of the present application is 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 the 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 of other components except the diluent in a planetary mixer to form a mixed slurry; then grind the mixed slurry six times on a ceramic three-roll grinder; test the fineness of the mixed slurry with a scraper fineness meter; control the slurry fineness to less than 10μm, add 0.1wt% diluent, and obtain a conductive paste.

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

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

[0139] The preparation methods of Examples 2 to 11 and Comparative Examples 1 to 2 are basically the same as those of Example 1, except that the formulas of the conductive pastes are different. Specifically, the formulas of the conductive pastes prepared in the examples and comparative examples are shown in Table 4.

[0140] Table 4

[0141]

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

[0143] Performance Testing

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

[0145] Table 5

[0146]

[0147] From the data in Table 5, it can be seen that compared with the cell prepared by the conventional P-zone conductive paste in Comparative Example 1, the photoelectric conversion efficiency of the cell obtained by using the conductive paste of the specific components of the present application in the P-zone in Examples 1 to 11 is significantly improved, the open circuit voltage is also improved, and the fill factor is significantly improved. It shows that the conductive paste provided by the present application reduces the composite loss rate of the P-zone of the TBC battery and greatly improves the ohmic contact effect. Comparative Example 1 uses a conventional TOPCon battery P-zone paste, in which Pb and B elements are relatively high, resulting in aggravated etching performance, poor overall fluidity of the glass system, poor silver microcrystal state, and poor ohmic contact effect.

[0148] In Comparative Example 2, the conductive paste used, although the content of Bi oxide was increased, the Pb element was low, resulting in weak corrosion ability, failure to form a good conductive channel, and failure to improve the filling factor. As a result, the battery cell prepared in Comparative Example 2 had poor ohmic contact and the electrical performance was inferior to that of Example 1.

[0149] It can be seen that the conductive paste obtained by the use of a specific composition ratio of the first glass powder and silver powder, inorganic additives and organic carriers can improve the ohmic contact in the battery cell, increase the open circuit voltage, and inhibit the recombination loss of carriers.

[0150] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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 above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims, and the description 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 carriers; in terms of mass percentage, the glass powder includes 28wt% to 100wt% of the first glass powder, 0 to 36wt% of the second glass powder and 0 to 36wt% of the third glass powder; In terms of molar percentage, the components of the first glass powder include TeO2 25mol% to 60mol%, PbO 15mol% to 35mol%, Bi2O3 1mol% to 15mol%, B2O3 0mol% to 10mol%, component a 1mol% to 50mol% and component b 0 to 25mol%; In terms of molar percentage, the components of the second glass powder include BaO 15mol% to 40mol%, SiO2 10mol% to 60mol%, B2O3 20mol% to 70mol% and component c 0 to 30mol%; In terms of molar percentage, 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%; Among them, the component a includes at least one of the oxides, carbonates and fluorides corresponding to Zn, P, Si, Al, W, Mg, Ca and Cu; the component b includes at least one of the alkali metal oxides, alkali metal fluorides and alkali metal carbonates; the component c includes at least one of the oxides, carbonates and fluorides corresponding to Pb, Al and Ca; the component d includes at least one of the oxides, carbonates and fluorides corresponding to Ti, Al, Cu, Zr, Ga and Zn.

2. The conductive paste according to claim 1, characterized in that: Calculated by weight percentage, the glass powder includes 70wt%-80wt% of the first glass powder, 18wt%-22wt% of the second glass powder and 4wt%-6wt% of the third glass powder.

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

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

5. The conductive paste according to 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) In the third glass powder component, the molar percentage of SiO2 is 15mol% to 43mol%; (3) In the third glass powder component, the molar percentage of B2O3 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 0mol% to 9mol%; (6) In the third glass powder component, the molar percentage of component d is 20 mol% to 56 mol%.

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

7. The conductive paste according to any one of claims 1 to 5, characterized in that: The inorganic additive includes at least one of elemental silicon powder particles, silicon dioxide powder and tungsten oxide powder particles.

8. The conductive paste according to any one of claims 1 to 5, characterized in that: The components of the organic carrier include solvent, resin, plasticizer and additive; The solvent is selected from at least one of alcohol ester dodecahydrate, alcohol ester hexadecene 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 auxiliary agent includes at least one of a diluent, stearic acid and polyamide.

9. The conductive paste according to claim 8, characterized in that: Based on the total mass of the conductive paste, the components of the organic vehicle include: 5wt% to 10wt% of the solvent, 1.2wt% to 2.6wt% of the resin, 0.4wt% to 1.5wt% of the plasticizer, and 0.1wt% to 0.9wt% of the auxiliary agent.

10. A battery, characterized in that: The battery comprises: 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 on the tunnel oxide layer and are alternately disposed at intervals; A first conductive layer disposed in the P-type doping region and a second conductive layer disposed in the N-type doping region; The raw material for preparing the first conductive layer includes the conductive paste according to any one of claims 1 to 9.

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