Composite materials and their preparation methods, conductive pastes, and methods for preparing conductive electrodes

Abstract

This application discloses a composite material and its preparation method, a conductive paste, and a method for preparing a conductive electrode, belonging to the field of conductive materials technology. The composite material includes: a metal core; an oxide layer, the oxide layer being deposited on at least a portion of the surface of the metal core; and a reducing agent layer, the reducing agent layer being deposited on at least a portion of the surface of the oxide layer. This application, through the design of the reducing agent layer, achieves in-situ reduction of the oxide on the surface of the metal core during high-temperature sintering, thereby improving the oxidation resistance of the metal core.

Description

Technical Field

[0001] This application relates to the field of conductive materials technology, specifically to a composite material and its preparation method, a conductive paste, and a method for preparing a conductive electrode. Background Technology

[0002] High-temperature conductive paste is an important technological field because it is widely used in many important applications in the electronics and photovoltaic industries.

[0003] To reduce the amount of silver used in conductive pastes, base metals are generally used as substitutes for silver.

[0004] During the research and practice of related technologies, the applicant discovered that some base metals are easily oxidized in air. Summary of the Invention

[0005] This application provides a composite material and its preparation method, a conductive slurry, and a method for preparing a conductive electrode, aiming to improve the conductivity of metal powders under high-temperature air sintering.

[0006] This application provides a composite material comprising: a metal core; an oxide layer covering at least a portion of the surface of the metal core; and a reducing agent layer covering at least a portion of the surface of the oxide layer.

[0007] Optionally, in some embodiments of this application, the metal core includes a metal material selected from at least one of base metals and base metal alloys; the oxide layer includes a metal oxide, which includes at least one of the corresponding oxides of the metal material; the reducing agent layer includes a reducing material that reduces the metal oxide to a metallic element under heating conditions.

[0008] Optionally, in some embodiments of this application, the heating conditions include: the heating temperature T satisfies: 500℃≤T≤800℃.

[0009] Optionally, in some embodiments of this application, the reducing agent layer includes a first adhering substance; the first adhering substance covers at least a portion of the surface of the oxide layer; the first adhering substance includes a carbon material, which undergoes a carbothermic reduction reaction with the metal oxide under the heating conditions.

[0010] Optionally, in some embodiments of this application, the reducing agent layer includes a second adhesive that covers at least a portion of the first adhesive.

[0011] Optionally, in some embodiments of this application, the second attachment includes an attachment material having a standard reduction potential lower than that of the metal material.

[0012] Optionally, in some embodiments of this application, the metal core and the oxide layer constitute a composite, and the mass ratio of the first attachment to the composite ranges from 0.005 to 0.075.

[0013] Optionally, in some embodiments of this application, the mass ratio of the second attachment to the composite ranges from 0.005 to 0.075.

[0014] Optionally, in some embodiments of this application, the median particle size of the composite is a first median particle size, the median particle size of the particles of the first attachment is a second median particle size, and the median particle size of the particles of the second attachment is a third median particle size; wherein the ratio of the second median particle size to the first median particle size ranges from 0.001 to 0.1.

[0015] Optionally, in some embodiments of this application, the ratio of the third median particle size to the first median particle size ranges from 0.001 to 0.1.

[0016] Optionally, in some embodiments of this application, the median particle size of the composite material ranges from 0.5 μm to 10.1 μm.

[0017] Optionally, in some embodiments of this application, the metal core includes one or more of copper, nickel, copper alloys, and nickel alloys.

[0018] Optionally, in some embodiments of this application, the metal core is selected from one or more of spherical, near-spherical, and sheet-like shapes.

[0019] Optionally, in some embodiments of this application, the first median particle size ranges from 0.5 μm to 10 μm.

[0020] Optionally, in some embodiments of this application, the first attachment includes one or more of carbon black, graphite, graphene, fullerene, and carbon nanotubes.

[0021] Optionally, in some embodiments of this application, the second median particle size ranges from 1 nm to 100 nm.

[0022] Optionally, in some embodiments of this application, the second attachment includes one or more of boron, iron, zinc, germanium, gallium, indium, and their alloys.

[0023] Optionally, in some embodiments of this application, the third median particle size ranges from 5 nm to 200 nm.

[0024] Accordingly, this application also provides a method for preparing a composite material, comprising: providing a composite body, the composite body comprising a metal core and an oxide layer covering at least a portion thereof on its surface; covering at least a portion of the surface of the composite body with a first material to form a first attachment; and covering at least a portion of the first attachment with a second material to form a second attachment.

[0025] Optionally, in some embodiments of this application, the conductive slurry includes conductive metal powder and an organic carrier, wherein the conductive metal powder includes the aforementioned composite material or the composite material prepared by the aforementioned preparation method.

[0026] Optionally, in some embodiments of this application, the conductive metal powder further includes silver powder, wherein the silver powder accounts for 10 wt% to 90 wt% of the conductive metal powder.

[0027] Optionally, in some embodiments of this application, the conductive slurry includes: the conductive metal powder accounting for 70wt% to 90wt% of the conductive slurry; and the organic carrier accounting for 10wt% to 30wt% of the conductive slurry.

[0028] Optionally, in some embodiments of this application, the conductive paste further includes glass frit; the glass frit accounts for 0.1wt% to 5wt% of the conductive paste.

[0029] In addition, this application also provides a method for preparing a conductive electrode, comprising the following steps: coating a conductive paste onto the surface of a substrate to form a conductive electrode precursor; and sintering the conductive electrode precursor to form the conductive electrode, wherein the sintering temperature ranges from 500°C to 800°C.

[0030] This application achieves in-situ reduction of oxides on the surface of the metal core during high-temperature sintering through the design of the reducing agent layer, thereby improving the oxidation resistance of the metal core and making it suitable for high-temperature conductive pastes in air atmosphere. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a structural example diagram of a composite material provided in one embodiment of this application, wherein the composite material includes a metal core, an oxide layer, and a reducing agent layer; Figure 2 This is a structural example diagram of a composite material provided in one embodiment of this application, wherein the reducing agent layer includes a first attachment; Figure 3 This is a structural example diagram of a composite material provided in one embodiment of this application, wherein the reducing agent layer includes a first attachment and a second attachment; Figure 4 This is a structural example diagram of a composite material provided in one embodiment of this application, wherein the reducing agent layer includes second attached particles; Figure 5 This is a SEM image of a composite material obtained by coating a spherical nickel powder core with carbon black in one embodiment of this application. Figure 6 This is a SEM image of a composite material with a spherical nickel powder core coated with carbon black and boron powder according to an embodiment of this application. Figure 7 This is a SEM image of a composite material obtained by coating a hydrangea-shaped nickel powder core with carbon black and boron powder according to an embodiment of this application. Figure 8 This is a SEM image of a composite material obtained by coating a spherical copper powder core with carbon black and boron powder according to an embodiment of this application.

[0033] Explanation of reference numerals in the attached figures: 10. Composite material; 100. Composite body; 110. Metal core; 120. Oxide layer; 130. Reducing agent layer; 131. First attachment; 132. Second attachment; 132a. Second attachment particles. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] This application provides a composite material and its preparation method, a conductive slurry, and a method for preparing a conductive electrode. These are described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative and do not impose numerical requirements or establish an order. Various embodiments of the present invention may exist in a range format; it should be understood that the description in a range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0036] This application provides a composite material and its preparation method, a conductive slurry, and a method for preparing a conductive electrode, aiming to improve the technical problem of the oxidation resistance of composite materials during high-temperature sintering.

[0037] High-temperature conductive pastes are an important technological field due to their widespread use in many critical applications within the electronics and photovoltaic industries. Silver is typically the preferred metal powder for high-temperature conductive pastes due to its excellent conductivity and good oxidation resistance. However, the high cost of silver is a major limiting factor. Therefore, the conductive paste field urgently needs to utilize lower-cost and more abundant base metals, including nickel and copper. However, the main challenge in using nickel and copper powders in conductive pastes is their susceptibility to oxidation in air, which significantly reduces their conductivity, making them unsuitable for high-temperature sintering applications. While high-temperature copper or nickel pastes can be sintered at high temperatures in an inert atmosphere (such as nitrogen), this significantly increases the process complexity and cost. Therefore, the conductive paste field urgently needs a base metal powder and paste that can achieve good conductivity under high-temperature air sintering.

[0038] like Figure 1 This application provides a composite material 10, comprising: a metal core 110; an oxide layer 120, the oxide layer 120 being disposed on at least a portion of the surface of the metal core 110; and a reducing agent layer 130, the reducing agent layer 130 being disposed on at least a portion of the surface of the oxide layer 120.

[0039] It is understandable that some base metals (such as nickel powder and copper powder) are easily oxidized in air, and an oxide layer 120 will naturally form on their surface. This application achieves in-situ reduction of the oxide on the surface of the metal core 110 during high-temperature sintering by designing a reducing agent layer 130, thereby improving the oxidation resistance of the metal core 110 and making it suitable for high-temperature conductive pastes in air.

[0040] In some embodiments of this application, the metal core 110 includes a metal material selected from at least one base metal and base metal alloy; the oxide layer 120 includes a metal oxide, which includes at least one of the corresponding oxides of the metal material; and the reducing agent layer 130 includes a reducing material that reduces the metal oxide to a metallic element under heating conditions.

[0041] It is understandable that the oxide layer 120 is the metal oxide corresponding to the metal material, and the reducing agent layer 130 can reduce the metal oxide to the metal element under heating conditions. The reduction reaction is achieved under conventional process conditions without the need for a special atmosphere.

[0042] In some embodiments of this application, the heating conditions include: the heating temperature T satisfies: 500℃≤T≤800℃.

[0043] In some examples, the heating temperature T satisfies any value or a range of any two of the following: 500℃, 550℃, 600℃, 650℃, 700℃, 720℃, 750℃, 780℃, and 800℃.

[0044] like Figure 2 As shown, in some embodiments of this application, the reducing agent layer 130 includes a first attachment 131; the first attachment 131 is applied to at least a portion of the surface of the oxide layer 120; the first attachment 131 includes a carbon material, which undergoes a carbothermic reduction reaction with the metal oxide under heated conditions.

[0045] Understandably, carbon materials, as a reducing medium, are widely available, low in cost, and highly efficient at high temperatures, which helps reduce process costs and improve reduction efficiency.

[0046] like Figure 3 As shown, in some embodiments of this application, the reducing agent layer 130 includes a second attachment 132, which covers at least a portion of the first attachment 131.

[0047] It is understandable that the second attachment 132 includes a material that can reduce the oxide layer 120 at high temperatures, and works synergistically with the first attachment 131 to further enhance the oxidation resistance of the composite material 10.

[0048] The second attachment 132 includes an attachment material, the standard reduction potential of which is lower than that of the metallic material.

[0049] It is understood that the second attachment 132 is a material with a reduction potential lower than that of the metal core 110, which further promotes reduction and inhibits oxidation at high temperatures. Based on the first attachment 131, this application adds a second attachment 132 to form a double-layer reducing agent structure, enhancing the protective and synergistic effects of the reducing agent and further improving the oxidation resistance of the metal core.

[0050] In some embodiments of this application, the metal core 110 and the oxide layer 120 constitute a composite 100, and the mass ratio of the first attachment 131 to the composite 100 ranges from 0.005 to 0.075.

[0051] In some embodiments of this application, the mass ratio of the second attachment 132 to the composite 100 ranges from 0.005 to 0.075.

[0052] It is understood that the mass ratio of the first attachment 131 to the composite 100 and the mass ratio of the second attachment 132 to the composite 100 in this application ensure uniform coating by the first attachment 131 and the second attachment 132, thereby improving the oxidation resistance of the composite material 10. The mass ratio of the first attachment 131 to the composite 100 can be any value from 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.04, 0.05, and 0.075, or a range of any two of these values. The mass ratio of the second attachment 132 to the composite 100 can be any value from 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.04, 0.05, 0.06, and 0.075, or a range of any two of these values.

[0053] In some embodiments of this application, the median particle size of the composite 100 is a first median particle size, the median particle size of the particles of the first attachment 131 is a second median particle size, and the median particle size of the particles of the second attachment 132 is a third median particle size; wherein the ratio of the second median particle size to the first median particle size ranges from 0.001 to 0.1.

[0054] like Figure 4 As shown, in some embodiments of this application, the second attachment 132 includes second attachment particles 132a, and the ratio of the third median particle size to the first median particle size of the second attachment particles 132a ranges from 0.001 to 0.1.

[0055] It is understood that the ratio of the third median particle size to the first median particle size, within the scope of this application, can enable the second adhering material 132 to effectively cover the composite 100, improving coating efficiency and structural stability. The ratio of the second median particle size to the first median particle size includes any value from 0.001, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.075, and 0.1, or a range of any two. The ratio of the third median particle size to the first median particle size includes any value from 0.001, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.075, and 0.1, or a range of any two.

[0056] In some embodiments of this application, the metal core 110 includes one or more of copper, nickel, copper alloys, and nickel alloys.

[0057] In some embodiments of this application, the metal core 110 is selected from one or more of spherical, near-spherical, and sheet-like shapes.

[0058] Specifically, the metal core 110 can be hydrangea-shaped. The surface microstructure of the hydrangea-shaped metal powder has higher activity, which helps to sinter at high temperature and form an electrode structure with higher conductivity. The higher activity of the microstructure has a higher requirement for oxidation resistance, such as the composite anti-oxidation structure of this application.

[0059] In some embodiments of this application, the median particle size of the composite material ranges from 0.5 μm to 10.1 μm.

[0060] It is understandable that the median particle size of the composite material can range from any value or a range of two of the following: 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1.0μm, 1.5μm, 2.0μm, 2.5μm, 3.0μm, 3.5μm, 4.0μm, 4.5μm, 5.0μm, 5.5μm, 6.0μm, 6.5μm, 7.0μm, 7.5μm, 8.0μm, 8.5μm, 9.0μm, 9.5μm, 10.0μm, and 10.1μm.

[0061] In some embodiments of this application, the first median particle size ranges from 0.5 μm to 10 μm. The first median particle size includes any value or a range of any two of 0.5 μm, 1.0 μm, 2.0 μm, 3.0 μm, 4.0 μm, 5.0 μm, 6.0 μm, 8.0 μm, and 10 μm.

[0062] In some embodiments of this application, the first attachment 131 includes one or more of carbon black, graphite, graphene, fullerene, and carbon nanotubes.

[0063] In some embodiments of this application, the second median particle size ranges from 1 nm to 100 nm.

[0064] It is understood that the second median particle size, within the scope of this application, is beneficial to improving the specific surface area and reactivity of the composite material 10. The value of the second median particle size includes any value or a range of any two of the following: 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 80 nm, and 100 nm.

[0065] In some embodiments of this application, the second attachment 132 includes one or more of boron, iron, zinc, germanium, gallium, indium and their alloys.

[0066] Specifically, when the metal core 110 includes at least one of nickel or nickel alloys, the second attachment 132 includes one or more of boron, iron, zinc, gallium, indium and their alloys; when the metal core 110 includes at least one of copper or copper alloys, the second attachment 132 includes one or more of boron, iron, zinc, germanium, gallium, indium and their alloys.

[0067] In some embodiments of this application, the third median particle size ranges from 5 nm to 200 nm.

[0068] It is understood that the values ​​of the first median particle size, the second median particle size, and the third median particle size are within the scope of this application, which can disperse the composite 100 with the first and second attachments, improve the uniformity of coating, and enhance the reactivity during subsequent sintering. The value of the third median particle size includes any value or a range of any two of the following: 5nm, 10nm, 30nm, 50nm, 70nm, 90nm, 120nm, 150nm, and 200nm.

[0069] Accordingly, this application also provides a method for preparing composite material 10, comprising: the preparation method including: S100: Provide a composite 100, the composite 100 including a metal core 110 and an oxide layer 120 covering at least a portion of its surface; S200: Applying the first material to at least a portion of the surface of the composite 100 to form a first attachment 131; S300: Apply the second material to at least a portion of the first attachment 131 to form the second attachment 132.

[0070] It is understood that this application provides a method for preparing composite material 10, which is simple and controllable in steps and suitable for large-scale production. The method achieves controllable structure and optimized performance through layer-by-layer coating.

[0071] In some embodiments of this application, the first material is coated onto at least a portion of the surface of the composite 100 to form a first attachment 131, including one or more of wet coating, dry coating, melt coating, vapor deposition, and plasma processing, and is not limited thereto. Coating equipment includes fluidized bed coaters, spray bed coaters, bottom-spray fluidized beds, rotary drums, disc coaters, fluidized bed reactors with chemical vapor deposition, and plasma-enhanced chemical vapor deposition, and is not limited thereto.

[0072] In some embodiments of this application, the second material is applied to at least a portion of the first attachment 131 to form the second attachment 132, including one or more of wet coating, dry coating, melt coating, vapor deposition, and plasma processing, and is not limited thereto. Coating equipment includes fluidized bed coaters, spray bed coaters, bottom-spray fluidized beds, rotary drums, disc coaters, fluidized bed reactors with chemical vapor deposition, and plasma-enhanced chemical vapor deposition, and is not limited thereto.

[0073] In some embodiments of this application, the conductive paste includes conductive metal powder and an organic carrier. The conductive metal powder includes the aforementioned composite material 10, or the composite material 10 prepared by the aforementioned preparation method.

[0074] Understandably, using composite material 10 as the conductive metal powder in the conductive slurry significantly improves the slurry's oxidation resistance and conductivity during high-temperature sintering, making it suitable for air atmosphere sintering and reducing costs. An organic carrier serves as the liquid phase in the conductive slurry to disperse the aforementioned solids, forming a slurry with a certain viscosity. The viscosity and rheological properties of this slurry ensure the long-term stable dispersion of the composite material 10 and allow the conductive slurry composition to be applied to the substrate surface.

[0075] In some examples, the organic carrier may include polymers and organic solvents. Polymers may include cellulose, resins, esters, etc. Cellulose includes cellulose resins such as methylcellulose, ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, benzylcellulose, propylcellulose, and nitrocellulose, or mixtures thereof. Resins include rosin, phenolic resins, acrylic resins, or mixtures thereof. Esters include polymethyl methacrylates of lower alcohols, etc. Organic solvents may include terpineol, diethylene glycol butyl ether acetate, diethylene glycol ethyl ether acetate, propylene glycol diacetate, α-hydroxymethyl ether acetate, etc. Terpenes, β Terpenes, dibutyl phthalate, butyl carbitol, butyl carbitol acetate, hexanediol, etc. Organic carriers may also include nonionic surfactants, thixotropic agents, dispersants, rheology modifiers, and other additives to suit different organic media requirements.

[0076] In some embodiments of this application, the conductive metal powder further includes silver powder, and the silver powder accounts for 10 wt% to 90 wt% of the conductive metal powder.

[0077] Understandably, conductive metal powders also contain silver powder, with the silver content adjustable between 10% and 90%, balancing conductivity and cost control to suit various performance requirements and cost-sensitive applications. When conductive pastes also contain silver powder, the proportion of composite materials in the conductive paste is correspondingly reduced to maintain 100% of the total mass of the conductive paste. The silver powder content in the conductive metal powder can be any value from 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, and 90wt%, or any range of both.

[0078] In some embodiments of this application, the conductive paste includes: conductive metal powder accounting for 70wt% to 90wt% of the conductive paste; and an organic carrier accounting for 10wt% to 30wt% of the conductive paste. The conductive metal powder accounting for 70wt%, 72wt%, 75wt%, 78wt%, 80wt%, 82wt%, 85wt%, 88wt%, and 90wt%, or any combination thereof. The organic carrier accounting for 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, 22wt%, 25wt%, 28wt%, and 30wt%, or any combination thereof.

[0079] In some embodiments of this application, the conductive paste further includes glass frit; the glass frit accounts for a range of 0.1wt% to 5wt% of the conductive paste. The glass frit accounts for any value or a range of any two of the following: 0.1wt%, 0.5wt%, 1.0wt%, 1.5wt%, 2.0wt%, 2.5wt%, 3.0wt%, 4.0wt%, and 5wt%.

[0080] Understandably, limiting the proportions of each component in the conductive paste, including metal powder, organic carrier, and optional glass frit, optimizes the paste's rheological properties, printability, and post-sintering adhesion, making it suitable for processes such as screen printing. When the conductive paste also includes glass frit, the proportion of conductive metal powder is correspondingly reduced to maintain 100% of the total mass of the conductive paste, with the total solids content ranging from 70% to 90%. The total solids content of the conductive paste can be any value or a range of any two values ​​from 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, and 90%.

[0081] Understandably, glass frit can act as an adhesive, helping to strengthen the bond between conductive electrodes and the substrate. Furthermore, glass frit can have a corrosive effect, which, in applications like photovoltaics, can corrode the passivation layer on the cell surface, thereby forming electrical contacts.

[0082] In addition, this application also provides a method for preparing a conductive electrode, comprising the following steps: coating a conductive paste onto the surface of a substrate to form a conductive electrode precursor; and sintering the conductive electrode precursor to form a conductive electrode, wherein the sintering temperature ranges from 500°C to 800°C.

[0083] It is understood that the method for preparing the conductive electrode of this application includes slurry coating and sintering steps. The sintering temperature is matched with the reduction temperature of the composite material 10, forming a highly conductive and highly adhesive electrode structure in an air atmosphere, which is suitable for photovoltaic, electronic and other fields. The sintering temperature can be any value or a range of any two of the following: 500℃, 550℃, 600℃, 650℃, 680℃, 700℃, 720℃, 750℃, and 800℃.

[0084] The following description, in conjunction with specific embodiments, illustrates the composite material and its preparation method, the conductive slurry, and the preparation method of the conductive electrode provided in this application: Example 1 The composite material was prepared according to the following steps, with all processes carried out under a nitrogen atmosphere: Step 1: Provide a composite material, which has the following characteristics: the metal core is spherical nickel powder (Ni-A, Shanghai Pantian), and the first median particle size is 2μm; Step 2: Using Wuxi Taixian Powder Equipment VSH-0.3, the first material is coated onto the surface of the composite material using a dry coating method to obtain the composite material; wherein the first adhering material is nano carbon powder (CB, Shanghai Pantian), and the second median particle size is 20nm.

[0085] The conductive paste is prepared according to the following steps: Step 3: Mix the composite material from Step 2 with the organic carrier at a mass ratio of 4:1, and roll the mixture using a three-roll mill (330 rpm, 5 minutes) to form a conductive slurry. The organic carrier, by 100% mass, includes: 15 wt% ethyl cellulose, 18 wt% polyvinyl butyral copolymer (PVB), 16 wt% diethylene glycol butyl ether acetate, 5 wt% silicone oil, 1.5 wt% Duomeen TDO (nonionic surfactant, belonging to the amine oxide category), 1.5 wt% Brij L4 (nonionic surfactant, belonging to the polyoxyethylene alcohol category), 6 wt% Thixotrol plus (rheology modifier), 30 wt% ethylenelated alcohol C12, and 7 wt% diester.

[0086] The conductive electrode is prepared according to the following steps: Step 4: Print the conductive paste onto the commercially available blue film of a crystalline silicon solar cell according to the designed pattern to form a patterned substrate; Step 5: Place the substrate in a muffle furnace and sinter it in an air atmosphere at a temperature of 800°C for 30 seconds to obtain a conductive electrode.

[0087] Example 2 The difference between this embodiment and embodiment 1 is that, in step 2, the mass ratio of the first attached substance to the composite is 0.05.

[0088] Example 3 The composite material was prepared according to the following steps, with all processes carried out under a nitrogen atmosphere: Step 1: Provide a composite material, which has the following characteristics: the metal core is spherical nickel powder (Ni-A, Shanghai Pantian), and the first median particle size is 2μm; Step 2: Using Wuxi Taixian Powder Equipment VSH-0.3, the first material is coated onto the surface of the composite using a dry coating method at a rotation speed of 3500 rpm for 60 minutes to form the first adhering material; the first material is nano carbon powder (CB, Shanghai Pantian), and the second median particle size is 20 nm; the mass ratio of the first adhering material to the composite is 0.05. Step 3: Using Wuxi Taixian Powder Equipment VSH-0.3, the second material is coated onto at least a portion of the surface of the first attachment using a dry coating method to form the second attachment. The rotation speed is 3500 rpm and the time is 60 minutes to obtain the composite material. The second material is nano boron powder (B, Shanghai Pantian), and the median particle size is 50 nm. The mass ratio of the second attachment to the composite is 0.025.

[0089] Example 4 The difference between this embodiment and embodiment 3 is that, in step 2, the mass ratio of the first attached material (nano-carbon powder, CB) to the composite is 0.005.

[0090] Example 5 The difference between this embodiment and embodiment 3 is that, in step 2, the mass ratio of the first attached material (nano-carbon powder, CB) to the composite is 0.01.

[0091] Example 6 The difference between this embodiment and embodiment 3 is that, in step 2, the mass ratio of the first adhering material (nano carbon powder, CB) to the composite is 0.025; and in step 3, the mass ratio of the second adhering material (nano boron powder, B) to the composite is 0.05.

[0092] Example 7 The difference between this embodiment and embodiment 3 is that, in step 2, the mass ratio of the first adhering substance (nano carbon powder, CB) to the composite is 0.05; and in step 3, the mass ratio of the second adhering substance (nano boron powder, B) to the composite is 0.005.

[0093] Example 8 The difference between this embodiment and embodiment 3 is that, in step 2, the mass ratio of the first adhering substance (nano carbon powder, CB) to the composite is 0.05; and in step 3, the mass ratio of the second adhering substance (nano boron powder, B) to the composite is 0.01.

[0094] Example 9 The difference between this embodiment and embodiment 3 is that, in step 3, the third median particle size of the second adhering material (nano boron powder, B) is 200 nm, and the mass ratio of the second adhering material to the composite is 0.025.

[0095] Example 10 The difference between this embodiment and embodiment 3 is that in step 2, the first material is nano-graphite powder (CG, Jinshun Carbon), the second median particle size is 100nm, and the mass ratio of the first adhering substance to the composite is 0.05.

[0096] Example 11 The difference between this embodiment and embodiment 3 is that step 2 is not performed; in step 3, the second material is directly coated on the surface of the composite to form the second attachment. The second material is nano iron powder (Fe, Shanghai Pantian), the third median particle size is 50nm, and the mass ratio of the second attachment to the composite is 0.01.

[0097] Comparative Example 1 The difference between this comparative example and Example 1 is that step 2 was not performed; that is, a metal core (spherical nickel powder Ni-A, Shanghai Pantian) was directly used as the comparative sample.

[0098] The composite materials provided in Examples 1 to 11 and Comparative Example 1 were used to prepare conductive pastes according to the formulations shown in Table 2, and conductive electrodes of Examples 12 to 22 and Comparative Example 2 were prepared.

[0099] Example 12 Prepare the conductive paste according to the following steps: The composite material obtained in Example 1 was mixed with an organic carrier at a mass ratio of 4:1 and rolled using a three-roll mill (330 rpm, 5 minutes) to form a conductive slurry. The organic carrier, by 100% mass, comprised: 15 wt% ethyl cellulose, 18 wt% polyvinyl butyral copolymer (PVB), 16 wt% diethylene glycol butyl ether acetate, 5 wt% silicone oil, 1.5 wt% Duomengen TDO (a nonionic surfactant belonging to the amine oxide category), 1.5 wt% Brij L4 (a nonionic surfactant belonging to the polyoxyethylene alcohol category), 6 wt% Thixotrol plus (rheology modifier), 30 wt% ethylenelated alcohol C12, and 7 wt% diester.

[0100] Prepare a conductive electrode according to the following steps: (1) The conductive paste is printed onto a commercially available blue film of a crystalline silicon solar cell according to the designed pattern to form a patterned substrate; (2) The patterned substrate is placed in a muffle furnace and sintered in an air atmosphere at a temperature of 800°C for 30 seconds to obtain a conductive electrode.

[0101] Example 13 The difference between this embodiment and embodiment 12 is that the composite material used is the same as that used in embodiment 2.

[0102] Example 14 The difference between this embodiment and embodiment 12 is that the composite material used is the same as that in embodiment 3.

[0103] Example 15 The difference between this embodiment and embodiment 12 is that the composite material used is the same as that in embodiment 4.

[0104] Example 16 The difference between this embodiment and embodiment 12 is that the composite material used is the same as that in embodiment 5.

[0105] Example 17 The difference between this embodiment and embodiment 12 is that the composite material used is the same as that in embodiment 6.

[0106] Example 18 The difference between this embodiment and embodiment 12 is that the composite material used is the same as that in embodiment 7.

[0107] Example 19 The difference between this embodiment and embodiment 12 is that the composite material used is the same as that in embodiment 8.

[0108] Example 20 The difference between this embodiment and embodiment 12 is that the composite material used is the same as that in embodiment 9.

[0109] Example 21 The difference between this embodiment and embodiment 12 is that the composite material used is the same as that used in embodiment 10.

[0110] Example 22 The difference between this embodiment and embodiment 12 is that the composite material used is the same as that used in embodiment 11.

[0111] Comparative Example 2 The difference between this comparative example and Example 12 is that the composite material used is the same as that in Comparative Example 1.

[0112] The composite material provided in Example 3 was used to prepare a conductive paste according to the formulation shown in Table 3. The conductive electrodes of Examples 23 to 25 and Comparative Examples 3 and 4 were prepared using the corresponding conductive paste.

[0113] Example 23 The difference between this embodiment and Embodiment 12 lies in the composition and proportion of the conductive paste. The composite material accounts for 70 wt% of the conductive paste. The conductive paste also includes 10 wt% silver powder, 0.3 wt% glass frit, and 19.7 wt% organic carrier. The glass frit, by mass percentage, comprises 30 wt% PbO, 30 wt% SiO2, 10 wt% TiO2, 20 wt% CuO, and 10 wt% ZnO. The composition of the organic carrier is the same as in Embodiment 12, and the preparation steps for the conductive paste and conductive electrode are the same as in Embodiment 12.

[0114] Example 24 The difference between this embodiment and Embodiment 12 lies in the composition and proportion of the conductive paste. The composite material accounts for 40 wt% of the conductive paste, which also includes 40 wt% silver powder, 0.3 wt% glass frit, and 19.7 wt% organic carrier. The composition of the organic carrier is the same as in Embodiment 12, and the preparation steps of the conductive paste and conductive electrode are the same as in Embodiment 12.

[0115] Example 25 The difference between this embodiment and Embodiment 12 lies in the composition and proportion of the conductive paste. The composite material accounts for 10 wt% of the conductive paste, which also includes 70 wt% silver powder, 0.3 wt% glass frit, and 19.7 wt% organic carrier. The composition of the organic carrier is the same as in Embodiment 1, and the preparation steps of the conductive paste and conductive electrode are the same as in Embodiment 12.

[0116] Referring to Table 4, the composite materials of Examples 26 to 29 and Comparative Example 5 were prepared.

[0117] Example 26 The difference between this embodiment and embodiment 3 is that, in step 1, the composite material is: hydrangea-shaped nickel powder (metal core is Ni-B, Changsha Liyou), with a first median particle size of 3μm; in step 2, the mass ratio of the first adhering material (nano carbon powder, CB) to the composite material is 0.01; in step 3, the mass ratio of the second adhering material (nano boron powder, B) to the composite material is 0.025.

[0118] Example 27 The difference between this embodiment and embodiment 3 is that in step 1, the composite uses hydrangea-shaped nickel powder (the metal core is Ni-B, Changsha Liyou), and the first median particle size is 3μm; in step 2, the mass ratio of the first adhering substance (nano carbon powder, CB) to the composite is 0.025; in step 3, the mass ratio of the second adhering substance (nano boron powder, B) to the composite is 0.05.

[0119] Example 28 The difference between this embodiment and embodiment 3 is that in step 1, the composite uses hydrangea-shaped nickel powder (the metal core is Ni-B, Changsha Liyou), and the first median particle size is 3μm; in step 2, the mass ratio of the first adhering substance (nano carbon powder, CB) to the composite is 0.05; in step 3, the mass ratio of the second adhering substance (nano boron powder, B) to the composite is 0.025.

[0120] Example 29 The difference between this embodiment and embodiment 3 is that in step 1, the composite uses hydrangea-shaped nickel powder (the metal core is Ni-B, Changsha Liyou), and the first median particle size is 3μm; in step 2, the mass ratio of the first adhering substance (nano carbon powder, CB) to the composite is 0.05; in step 3, the mass ratio of the second adhering substance (nano boron powder, B) to the composite is 0.01.

[0121] Comparative Example 5 The difference between this comparative example and Example 3 is that in step 1, the composite uses hydrangea-shaped nickel powder (with a metal core of Ni-B, Changsha Liyou) and the first median particle size is 3μm; steps 2 and 3 were not performed, that is, the hydrangea-shaped nickel powder was directly used as the comparison sample.

[0122] Referring to Table 5, the composite materials of Examples 30 to 33 and Comparative Example 6 were prepared.

[0123] Example 30 The difference between this embodiment and embodiment 3 is that in step 1, the composite uses spherical copper powder (with a metal core of Cu-A, silver-based) and the first median particle size is 4 μm; in step 2, the mass ratio of the first adhering substance (nano carbon powder, CB) to the composite is 0.01; in step 3, the mass ratio of the second adhering substance (nano boron powder, B) to the composite is 0.025 and the third median particle size is 50 nm.

[0124] Example 31 The difference between this embodiment and Embodiment 3 is that, in step 1, the composite uses spherical copper powder (with a metal core of Cu-A, silver-based) and a first median particle size of 4 μm; in step 2, the mass ratio of the first adhering substance (nano carbon powder, CB) to the composite is 0.05; in step 3, the mass ratio of the second adhering substance (nano boron powder, B) to the composite is 0.025 and the third median particle size is 50 nm.

[0125] Example 32 The difference between this embodiment and Embodiment 3 is that, in step 1, the composite uses spherical copper powder (with a metal core of Cu-A, silver-based) and a first median particle size of 4 μm; in step 2, the mass ratio of the first adhering substance (nano carbon powder, CB) to the composite is 0.025; in step 3, the mass ratio of the second adhering substance (nano boron powder, B) to the composite is 0.075 and the third median particle size is 50 nm.

[0126] Example 33 The difference between this embodiment and Embodiment 3 is that, in step 1, the composite uses spherical copper powder (with a metal core of Cu-A, silver-based) and a first median particle size of 4 μm; in step 2, the mass ratio of the first adhering substance (nano carbon powder, CB) to the composite is 0.075; in step 3, the mass ratio of the second adhering substance (nano boron powder, B) to the composite is 0.025 and the third median particle size is 50 nm.

[0127] Comparative Example 6 The difference between this comparative example and Example 3 is that in step 1, the composite uses spherical copper powder (with a metal core of Cu-A and silver) and the first median particle size is 4 μm; steps 2 and 3 were not performed, that is, the spherical copper powder was directly used as the control sample.

[0128] The composite materials provided in Examples 30 to 33 and Comparative Example 6 were used to prepare conductive pastes according to the formulations shown in Table 6. The corresponding conductive pastes were then used to prepare conductive electrodes for Examples 34 to 37 and Comparative Example 7.

[0129] Example 34 Prepare the conductive paste according to the following steps: The composite material obtained in Example 30 was mixed with an organic carrier at a mass ratio of 4:1 and rolled on a three-roll mill (330 rpm, 5 minutes) to form a conductive slurry. The organic carrier, by 100% mass, included: 15 wt% ethyl cellulose, 18 wt% polyvinyl butyral copolymer (PVB), 16 wt% diethylene glycol butyl ether acetate, 5 wt% silicone oil, 1.5 wt% Duomenen TDO (nonionic surfactant, belonging to the amine oxide category), 1.5 wt% Brij L4 (nonionic surfactant, belonging to the polyoxyethylene alcohol category), 6 wt% Thixotrol plus (rheology modifier), 30 wt% ethylene-substituted alcohol C12, and 7 wt% diester.

[0130] Prepare a conductive electrode according to the following steps: (1) The conductive paste is printed onto a commercially available blue film of a crystalline silicon solar cell according to the designed pattern to form a patterned substrate; (2) The patterned substrate is placed in a muffle furnace and sintered at 500°C and 800°C in an air atmosphere for 30 seconds to obtain conductive electrodes.

[0131] Example 35 The difference between this embodiment and embodiment 34 is that the composite material used is the same as that in embodiment 31.

[0132] Example 36 The difference between this embodiment and embodiment 34 is that the composite material used is the same as that used in embodiment 32.

[0133] Example 37 The difference between this embodiment and embodiment 34 is that the composite material used is the same as that used in embodiment 33.

[0134] Comparative Example 7 The difference between this comparative example and Example 34 is that the composite material used is the same as that in Comparative Example 6.

[0135] Figure 5 The composite material coated with carbon black obtained in Example 2; Figure 6 Example 3 yielded a composite material with a spherical nickel powder core; Figure 7 Example 28 yielded a composite material with a hydrangea-shaped nickel powder core; Figure 8 Example 31 yielded a composite material with a spherical copper powder core.

[0136] Test methods Antioxidant properties: evaluated by thermogravimetric analysis. Specifically, the sample is heated from room temperature to the target temperature (e.g., 600°C or 800°C) at a constant rate of 10°C / min in air. The antioxidant properties are characterized by measuring the percentage change in mass (Δwt%) of the sample during heating; the smaller the increase in mass, the better the antioxidant properties of the material.

[0137] The resistivity testing method for conductive electrodes: A four-probe resistivity meter is used to test the resistivity of conductive electrodes sintered according to the above method. Before testing, the width and thickness of the sintered conductive electrode grid lines are measured using an optical microscope or a profilometer, and their cross-sectional area is calculated. During testing, the four-probe probe is vertically pressed onto the surface of the conductive electrode grid lines. At a constant temperature (e.g., 25±1℃), a constant current is applied to the two outer probes, and the voltage difference between the two inner probes is measured. The volume resistivity of the conductive electrode is directly read or calculated using the instrument's built-in algorithm combined with the input cross-sectional area parameters (in ohms-cm). At least five different locations on each sample are tested, and the average value is taken as the final resistivity value.

[0138] Tables 1 to 6 contain relevant data for the embodiments and comparative examples of this application.

[0139] According to Examples 1 to 11 and Comparative Example 1 of this application, the composite material provided by this application includes a metal core, an oxide layer at least partially covering the surface of the metal core, and a reducing agent layer at least partially covering the surface of the oxide layer. The composite of Comparative Example 1 did not have a reducing agent layer on its surface. The results show that the composite materials of Examples 1 to 11 all exhibit better oxidation resistance under heated conditions. This indicates that the design of the reducing agent layer enables in-situ reduction of the oxides on the surface of the metal core during high-temperature sintering, thereby improving the oxidation resistance of the metal core.

[0140] According to Embodiments 2, 3, and 10 of this application, the composite material provided in this application includes a first attach material in the reducing agent layer, which comprises a carbon material. Embodiment 2 uses only carbon material as the first attach material. Embodiment 3 further includes a second attach material based on the first attach material, the second attach material comprising an attaching material whose standard reduction potential is lower than that of the metal core. Embodiment 10 uses carbon materials of different types and particle sizes as the first attach material. The results show that, compared to the scheme with only a first attach material, the composite material with both a first and a second attach material can more effectively reduce metal oxides to elemental metals under heating conditions, further improving oxidation resistance and demonstrating the synergistic protective and reducing effect of the double-layer reducing agent structure.

[0141] According to embodiments 3 to 8 of this application, in the composite material provided by this application, the metal core and the oxide layer constitute a composite. When the mass ratio of the first attachment to the composite and the mass ratio of the second attachment to the composite are within the range specified in this application, uniform coating of the composite by the first and second attachments can be achieved. Results show that within the above-mentioned mass ratio range, the composite material can achieve good oxidation resistance under heating conditions. A reasonable mass ratio design helps to form an effective reducing agent layer coating structure, thereby ensuring the full progress of the reduction reaction.

[0142] According to Examples 3 to 5 of this application, in the composite material provided by this application, when the mass ratio of the first adhesive to the composite changes within the range specified in this application, effective adhesion of the second adhesive and the antioxidant properties of the composite material can be achieved. The results show that within this mass ratio range, the first adhesive can provide a good adhesion base for the second adhesive, and the two work synergistically to improve the structural stability and reduction capacity of the composite material under heated conditions.

[0143] According to Embodiments 3, 7, and 8 of this application, the composite material provided by this application exhibits good oxidation resistance when the mass ratio of the second adhering substance to the composite material varies within the range specified in this application. The results show that within this mass ratio range, the second adhering substance can effectively cover the surface of the first adhering substance and fully exert its reducing effect under heating conditions, reducing metal oxides to elemental metals, demonstrating the rationality and effectiveness of the second adhering substance content design.

[0144] According to Embodiments 3 and 10 of this application, the first adhering material in the composite material provided by this application can be selected from different types of carbon materials, such as carbon black or graphite. Results show that when different types of carbon materials are used as the first adhering material, they can all undergo a carbothermic reduction reaction with metal oxides under heating conditions. Furthermore, when used in conjunction with a second adhering material, the reduction effect can be further enhanced. This indicates that the selection of the first adhering material in this application has broad applicability and can meet different process and performance requirements.

[0145] According to Examples 12 to 22 and Comparative Example 2 of this application, Comparative Example 2 used a gold composite without a reducing agent layer to prepare a conductive paste. The resistivity of the conductive electrode formed after sintering was higher than that of Examples 12 to 22, and the conductivity was poor. This indicates that the design of the reducing agent layer enables in-situ reduction of oxides on the surface of the metal core during high-temperature sintering, thereby improving the oxidation resistance of the metal core and thus improving the conductivity of the conductive electrode.

[0146] Examples 14 to 22 are composite materials with both a first and a second attachment. Test results show that the resistivity of the conductive electrodes in these examples is significantly lower than that of the scheme with only the first attachment (Examples 12 to 13) and Comparative Example 2. This indicates that the synergistic effect of the first and second attachments can more effectively reduce the oxides on the surface of the metal core during high-temperature air sintering, thereby significantly improving the conductivity of the conductive electrodes.

[0147] According to Examples 23 to 25 and Comparative Examples 3 and 4 of this application, the conductive paste provided by this application includes conductive metal powder and an organic carrier, wherein the conductive metal powder includes the composite material of this application. The conductive pastes of Comparative Examples 3 and 4 employ a metal core without a reducing agent layer. The results show that the conductive electrode formed after sintering of the conductive paste using the composite material of this application has a lower resistivity. This indicates that the composite material of this application effectively exerts an in-situ reduction effect during the high-temperature sintering process in the conductive paste, inhibiting the oxidation of the metal core, thereby significantly improving the conductivity of the conductive electrode. When the composite material of this application is mixed with silver powder, it can fully exert its in-situ reduction effect during the high-temperature sintering process, effectively inhibiting the oxidation of base metals, and forming a good synergistic conductive network with the silver powder. Even when the silver powder content is high, the introduction of the composite material can further optimize the contact between the conductive metal powders and reduce the electrode resistance. At the same time, the addition of glass frit helps to enhance the stable connection between the conductive electrode and the substrate, comprehensively improving the conductivity and reliability of the electrode.

[0148] According to Embodiment 24 and Comparative Example 3 of this application, the conductive metal powder in the conductive slurry provided by this application includes a composite material, and the range of values ​​for both the conductive metal powder and silver powder in the conductive metal powder are within the scope of this application. The conductive slurry of Comparative Example 3 uses a metal core without a reducing agent layer. The results show that, with the same amount of silver powder added, the conductive electrode made from the conductive slurry containing the composite material of this application has superior conductivity. This indicates that the composite material of this application can effectively maintain or even improve the overall conductivity of the conductive slurry when partially replacing silver powder.

[0149] According to Embodiment 25 and Comparative Example 4 of this application, the conductive slurry provided in this application includes a composite material as the conductive metal powder, and when silver powder accounts for a high proportion of the conductive metal powder, the composite material and silver powder work synergistically. The conductive slurry of Comparative Example 4 uses a metal core without a reducing agent layer mixed with silver powder. The results show that, at the same high silver content, the conductive electrode prepared from the conductive slurry containing the composite material of this application exhibits a lower resistivity. This indicates that even with a high proportion of silver powder, the composite material of this application can still optimize the contact between conductive metal powders through its own antioxidant and reducing properties, further improving the conductivity of the electrode.

[0150] According to Examples 26 to 29 and Comparative Example 5 of this application, the composite material provided by this application includes a metal core, an oxide layer covering at least a portion of the surface of the metal core, and a reducing agent layer covering at least a portion of the surface of the oxide layer. The metal cores of Examples 26 to 29 have a hydrangea morphology, while the hydrangea-shaped composite of Comparative Example 5 does not have a reducing agent layer on its surface. The results show that the composite materials of Examples 26 to 29 all exhibit better oxidation resistance under heated conditions. This indicates that even for hydrangea-shaped metal cores with higher surface microstructure activity, the reducing agent layer design of this application can still achieve in-situ reduction of oxides on the surface of the metal core during high-temperature sintering, effectively inhibiting oxidation and improving its high-temperature oxidation resistance.

[0151] According to embodiments 26 to 29 of this application, the composite material provided in this application uses hydrangea-shaped nickel powder as the composite body. When the mass ratio of the first attachment to the composite body and the mass ratio of the second attachment to the composite body vary within the range specified in this application, the composite material exhibits good oxidation resistance. The results show that for the hydrangea-shaped composite body, by adjusting the mass ratio of the first and second attachments, the reducing agent layer can be effectively coated on the composite body with a complex surface microstructure. Within the aforementioned mass ratio range, the first and second attachments work synergistically to reduce metal oxides to elemental metals under heating conditions, thereby improving the oxidation resistance of the composite material and demonstrating the broad applicability of the technical solution of this application to metal cores with different morphologies.

[0152] According to Examples 30 to 33 and Comparative Example 6 of this application, the composite material provided by this application includes a metal core, an oxide layer at least partially coated on the surface of the metal core, and a reducing agent layer at least partially coated on the surface of the oxide layer. The composites in Examples 30 to 33 use spherical copper powder, while the copper powder in Comparative Example 5 does not have a reducing agent layer on its surface. The results show that the composite materials of Examples 30 to 33 exhibit better oxidation resistance under heated conditions, and the conductive electrodes prepared from them have lower resistivity at different sintering temperatures. This indicates that for easily oxidized base metals such as copper, the reducing agent layer design of this application can achieve in-situ reduction of the oxides on the surface of the metal core during high-temperature sintering, effectively inhibiting oxidation, thereby improving the high-temperature oxidation resistance and conductive stability of the copper metal core.

[0153] According to embodiments 30 to 33 of this application, in the composite material provided by this application, the metal core is made of copper, and the metal core and oxide layer constitute a composite. When the mass ratio of the first attachment to the composite and the mass ratio of the second attachment to the composite vary within the range specified in this application, the composite material exhibits good oxidation resistance. The results show that for a copper metal core, effective coating of the reducing agent layer can be achieved by adjusting the mass ratio of the first and second attachments. Within the aforementioned mass ratio range, the carbon material included in the first attachment undergoes a carbothermic reduction reaction with the metal oxide under heating conditions. Simultaneously, the attachment material included in the second attachment (whose standard reduction potential is lower than that of the copper metal material) further promotes the reduction process. The two work synergistically to reduce the metal oxide to elemental metal. This demonstrates that the technical solution of this application can effectively improve the oxidation resistance and electrical conductivity of the copper metal core under different sintering conditions, reflecting the broad applicability of this application to various base metal materials.

[0154] According to Examples 34 to 37 and Comparative Example 7 of this application, the conductive slurry of Comparative Example 7 exhibited a high resistivity of the conductive electrode after sintering in an air atmosphere, especially at lower sintering temperatures. Examples 34 to 37 used the composite material of this application coated with a first and a second adhering substance, with copper powder as the metal core. The conductive electrodes prepared at both sintering temperatures showed excellent conductivity. The resistivity of each example was significantly lower than that of Comparative Example 7. Furthermore, the composite material of Examples 34 to 37 achieved good conductivity even at a lower sintering temperature of 500°C, indicating that the reducing agent layer could effectively exert carbothermic reduction and synergistic reduction effects at this temperature, reducing the oxides on the surface of the metal core to elemental metal. At a higher sintering temperature of 800°C, the resistivity of the conductive electrode further decreased, reflecting the complete progress of the reduction reaction and good sintering connection between metal particles, thus improving the conductivity of the conductive electrode. The composite material of this application has wide applicability at different process temperatures.

[0155] Table 1

[0156] Table 2

[0157] Table 3

[0158] Table 4

[0159] Table 5

[0160] Table 6

[0161] The foregoing has provided a detailed description of a composite material and its preparation method, a conductive slurry, and a method for preparing a conductive electrode, as provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A composite material (10), characterized in that, The composite material (10) includes: Metal core (110); An oxide layer (120) is disposed on at least a portion of the surface of the metal core (110); A reducing agent layer (130) is disposed on at least a portion of the surface of the oxide layer (120).

2. The composite material (10) according to claim 1, characterized in that, The metal core (110) includes a metallic material selected from at least one of base metals and base metal alloys; The oxide layer (120) comprises a metal oxide, which includes at least one of the corresponding oxides of the metal material; The reducing agent layer (130) includes a reducing material that reduces the metal oxide to a metallic element under heating conditions.

3. The composite material (10) according to claim 2, characterized in that, The heating conditions include: The heating temperature T satisfies: 500℃≤T≤800℃.

4. The composite material (10) according to claim 3, characterized in that, The reducing agent layer (130) includes a first attachment (131); The first attachment (131) covers at least a portion of the surface of the oxide layer (120); The first attachment (131) comprises a carbon material, which undergoes a carbothermic reduction reaction with the metal oxide under the heating conditions.

5. The composite material (10) according to claim 4, characterized in that, The reducing agent layer (130) includes a second attachment (132) which covers at least a portion of the first attachment (131).

6. The composite material (10) according to claim 5, characterized in that, The second attachment (132) includes an attachment material having a standard reduction potential lower than that of the metal material.

7. The composite material (10) according to claim 5 or 6, characterized in that, The metal core (110) and the oxide layer (120) constitute a composite (100), and the mass ratio of the first attachment (131) to the composite (100) ranges from 0.005 to 0.

075. And / or, the mass ratio of the second attachment (132) to the composite (100) ranges from 0.005 to 0.

075.

8. The composite material (10) according to claim 5 or 6, characterized in that, The metal core (110) and the oxide layer (120) constitute a composite (100), the median particle size of the composite (100) is a first median particle size, the median particle size of the particles of the first attachment (131) is a second median particle size, and the median particle size of the particles of the second attachment (132) is a third median particle size. The ratio of the second median particle size to the first median particle size ranges from 0.001 to 0.

1. And / or, the ratio of the third median particle size to the first median particle size ranges from 0.001 to 0.1; And / or, the median particle size of the composite material ranges from 0.5 μm to 10.1 μm.

9. The composite material (10) according to claim 8, characterized in that, The metal core (110) includes one or more of copper, nickel, copper alloys, and nickel alloys; And / or, the metal core (110) is selected from one or more of spherical, near-spherical, and sheet-like shapes; And / or, the first median particle size ranges from 0.5 μm to 10 μm.

10. The composite material (10) according to claim 8, characterized in that, The first attached material (131) includes one or more of carbon black, graphite, graphene, fullerene, and carbon nanotubes; And / or, the second median particle size ranges from 1 nm to 100 nm.

11. The composite material (10) according to claim 8, characterized in that, The second adhering material (132) includes one or more of boron, iron, zinc, germanium, gallium, indium and their alloys; And / or, the third median particle size ranges from 5 nm to 200 nm.

12. A method for preparing a composite material (10) as described in any one of claims 1 to 11, characterized in that, The preparation method includes: A composite (100) is provided, the composite (100) comprising a metal core (110) and an oxide layer (120) covering at least a portion of its surface. The first material is applied to at least a portion of the surface of the composite (100) to form a first attachment (131). The second material is applied to at least a portion of the first attachment (131) to form a second attachment (132).

13. A conductive paste, characterized in that, The conductive slurry comprises conductive metal powder and an organic carrier, wherein the conductive metal powder comprises the composite material (10) according to any one of claims 1 to 11, or the composite material (10) prepared by the preparation method according to claim 12.

14. The conductive paste according to claim 13, characterized in that, The conductive metal powder also includes silver powder, and the silver powder accounts for 10 wt% to 90 wt% of the conductive metal powder.

15. The conductive paste according to claim 13, characterized in that, The conductive paste includes: The conductive metal powder accounts for 70 wt% to 90 wt% of the conductive slurry. The organic carrier accounts for 10 wt% to 30 wt% of the conductive paste.

16. The conductive paste according to claim 15, characterized in that, The conductive paste also includes glass material; The glass component accounts for 0.1 wt% to 5 wt% of the conductive paste.

17. A method for preparing a conductive electrode, characterized in that, The preparation method includes the following steps: A conductive paste is coated onto the surface of a substrate to form a conductive electrode precursor. The conductive electrode precursor is sintered to form the conductive electrode, and the sintering temperature ranges from 500℃ to 800℃.

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