Surface modified silver powder, conductive silver paste and preparation method and application of surface modified silver powder and conductive silver paste

Abstract

The invention belongs to the technical field of silver powder surface modification, and particularly relates to surface modified silver powder, conductive silver paste and a preparation method and application of the conductive silver paste. The surface modified silver powder comprises silver powder particles and a coating agent coating the surfaces of the silver powder particles, wherein the surface modified silver powder is provided with a densified structure and a nanoscale surface fine grain layer which are formed after chemical modification and physical high-speed fusion treatment.

Description

Technical Field

[0001] This invention belongs to the field of silver powder surface modification technology, specifically relating to a surface-modified silver powder, conductive silver paste, its preparation method and application. Background Technology

[0002] Photovoltaic silver paste is an indispensable key material in the metallization process of crystalline silicon solar cells, and its performance directly determines the conductivity, reliability, and photoelectric conversion efficiency of the solar cell electrodes. As the most core and cost-intensive component of photovoltaic silver paste, the inherent characteristics of silver powder, such as morphology, particle size distribution, dispersibility, and surface state, fundamentally determine the rheological properties, printability, sinterability, and electrical properties of the final silver paste. With the iterative upgrades of photovoltaic technology, especially high-efficiency cell technologies represented by TOPCon cells, higher requirements have been placed on the fine grid line printing, and the linewidth of silver electrodes is constantly narrowing, which brings unprecedented challenges to the overall performance of silver powder.

[0003] To improve the performance of silver powder, existing technologies typically employ surface modification methods, with chemical coating being a common technique. This method involves coating the surface of silver powder particles with one or more layers of small organic molecules or polymers to improve the dispersibility and stability of the silver powder in an organic carrier and reduce particle agglomeration. However, simple chemical coating methods have limitations. They offer limited improvement to the morphology of the silver powder particles themselves (such as sphericity and surface roughness), strong van der Waals forces may still exist between particles leading to agglomeration, and the uniformity and firmness of the coating layer are difficult to guarantee. These shortcomings result in conductive silver pastes prepared using this type of modified silver powder exhibiting deficiencies in flowability, thixotropy, and long-term storage stability, failing to fully meet the requirements for high-performance solar cell fabrication.

[0004] Therefore, a pressing technical problem in this field is the difficulty of providing a silver powder that possesses both excellent physical morphology and ideal surface chemical state. Specifically, there is a lack of silver powder whose particles exhibit high sphericity and low agglomeration, while simultaneously forming a highly dense, uniform, and robust functionalized coating structure on its surface. This inherent structural defect is the root cause of problems such as high viscosity, unstable rheology, and easy diffusion of printed lines in existing conductive silver paste products, thus hindering further improvements in the photoelectric conversion efficiency of solar cells. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a surface-modified silver powder, a conductive silver paste, its preparation method and application.

[0006] Firstly, a surface-modified silver powder, employing the following technical solution:

[0007] A surface-modified silver powder includes silver powder particles and a coating agent coating the surface of the silver powder particles; wherein the surface-modified silver powder has a densified structure and a nanoscale surface fine grain layer formed by chemical modification and high-speed physical fusion treatment.

[0008] Furthermore, the mass of the coating agent is 0.1 wt% to 1.0 wt% of the mass of the silver powder particles.

[0009] Furthermore, the particle size of the silver powder is 0.3μm-5.0μm.

[0010] Furthermore, the silver powder particles are selected from at least one of spherical silver powder, spherical silver powder, and microcrystalline silver powder.

[0011] Furthermore, the coating agent is a fatty acid compound or an oleamine compound.

[0012] Furthermore, the coating agent is selected from at least one of fatty acid compounds, aliphatic compounds, oleic acid compounds, silane coupling agents, and amino-containing small molecule compounds.

[0013] Secondly, a method for preparing surface-modified silver powder adopts the following technical solution:

[0014] A method for preparing surface-modified silver powder includes the following steps:

[0015] The silver powder particles are surface-modified with a coating agent to obtain chemically modified silver powder.

[0016] The chemically modified silver powder is subjected to high-speed fusion processing to obtain the surface-modified silver powder.

[0017] Furthermore, in the high-speed fusion processing step, the modification temperature is 15℃-80℃, the modification frequency is 10Hz-60Hz, and the modification time is 3min-120min.

[0018] Thirdly, a conductive silver paste employs the following technical solution:

[0019] A conductive silver paste, by mass fraction, comprises the following components: 85wt%-90wt% of surface-modified silver powder as described in claim 1, 2.0wt%-3.0wt% of glass powder, 1.0wt%-2.0wt% of aluminum powder, 0.1wt%-0.5wt% of acrylic resin, 1.0wt%-2.0wt% of thixotropic agent, 5wt%-10wt% of organic solvent, and 0.1wt%-0.5wt% of dispersant.

[0020] Fourthly, the application of a conductive silver paste employs the following technical solution:

[0021] Application of a conductive silver paste in the preparation of the front-side material of TOPCon batteries.

[0022] The beneficial effects of this invention are:

[0023] This invention provides a surface-modified silver powder that fundamentally solves the technical challenge of simultaneously achieving the desired physical morphology and surface chemical state of silver powder in existing technologies. This structure not only improves the sphericity and surface density of the silver powder particles, effectively reducing particle agglomeration, but also ensures that the coating agent forms a uniform and robust nanoscale functional layer on the silver powder surface. The conductive silver paste prepared using this surface-modified silver powder exhibits excellent macroscopic properties such as flowability, stability, and dispersibility. Simultaneously, its thixotropy, recovery, and t50 properties are significantly improved, thus meeting the stringent requirements of next-generation high-efficiency solar cells for fine electrode printing and providing crucial material support for improving the photoelectric conversion efficiency of the cells. Attached Figure Description

[0024] Figure 1 SEM image of spherical silver powder that has not undergone high-speed fusion modification.

[0025] Figure 2 This is a SEM image of the surface-modified silver powder obtained in Example 1 of the present invention.

[0026] Figure 3 This is a SEM image of the surface-modified silver powder obtained in Example 2 of the present invention.

[0027] Figure 4 This is a SEM image of the surface-modified silver powder obtained in Example 3 of the present invention.

[0028] Figure 5 This is a SEM image of the surface-modified silver powder obtained in Example 4 of the present invention.

[0029] Figure 6 This is a SEM image of the surface-modified silver powder obtained in Comparative Example 1 of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the present application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limitations on the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0031] In the following description, references to "some embodiments" refer to a subset of all possible embodiments; however, it is understood that "some embodiments" may be the same or different subsets of all possible embodiments and may be combined with each other without conflict. Unless otherwise defined, all technical and scientific terms used in the embodiments of the invention have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of the invention pertain. The terminology used in the embodiments of the invention is for the purpose of describing the embodiments of the invention only and is not intended to limit the invention.

[0032] Those skilled in the art should understand that, in the following description of the embodiments of the present invention, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0033] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0034] Those skilled in the art will understand that the numerical ranges in the embodiments of the present invention should be understood to specifically disclose each intermediate value between the upper and lower limits of the range. Each smaller range between any stated value and an intermediate value within the stated range, as well as any other stated value or an intermediate value within the stated range, is also included within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0035] Unless otherwise stated, the technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in embodiments or test cases of the invention. All references to this specification are generally incorporated herein by reference to disclose and describe methods and / or materials associated with said references. In the event of any conflict with any incorporated reference, the contents of this application shall prevail.

[0036] It should be noted that all raw materials and / or reagents in the embodiments of the present invention were purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0037] Example

[0038] Example 1

[0039] The silver powder surface modification method combining chemical modification and high-speed mechanical fusion provided in Example 1 specifically includes the following steps:

[0040] S1, Chemically Modified Silver Powder: Utilizing stearic acid (C... 17 H 35 Coating and modifying spherical silver powder with COOH yields stearic acid (C... 17 H 35 The silver powder, modified with COOH, is a near-spherical shape; it exhibits monodispersity with a D50 range of 1.1-1.2 μm and a D90 of 2.4 μm; stearic acid (C 17 H 35 COOH) and stearic acid (C 17 H 35 The mass ratio of COOH-modified spherical silver powder is 0.5%.

[0041] S2, Physically Modified Silver Powder: Weigh 1000g of stearic acid (C 17 H 35 The COOH-modified spherical silver powder was added into the reactor of a high-speed fusion machine for high-speed fusion modification to obtain high-speed fusion modified spherical silver powder; the high-speed fusion modification machine had a frequency of 20Hz, a processing time of 6min, and a processing temperature of 6℃-10℃.

[0042] S3. Modified finished product: The spherical silver powder modified by high-speed fusion is taken out from the fusion machine, sieved and packaged to obtain the composite modified product.

[0043] In the modification process, first weigh out the coating agent stearic acid (C 17 H 35 Chemical modification of spherical silver powder with COOH yields stearic acid (C... 17 H 35 Spherical silver powder modified with COOH; secondly, stearic acid (C 17 H 35 The spherical silver powder modified with COOH was added to the vessel of a high-speed fusion modifier. Then, the modification parameters were set, and the stearic acid (C) was modified under high speed in the high-speed fusion modifier. 17 H 35 The spherical silver powder modified with COOH underwent physical modification treatment, resulting in a more compact structure, a smoother and rounder surface, and higher sphericity. Furthermore, the stearic acid (C...) in the reactor of the high-speed fusion modifier... 17 H 35The COOH-modified near-spherical silver powder undergoes a three-dimensional flow under the tilting and high-speed rotation of the rotor. Impact, compressive, and shear forces generated by collisions between the rotor, the wall, and the powder continuously exert stress on the silver powder. The process of micro-powder solidification on the masterbatch surface, accompanied by a composite effect, is repeated, achieving both densification and sphericity, significantly improving the wettability of the silver powder to organic systems and the thixotropic properties of the slurry.

[0044] Example 2

[0045] The silver powder surface modification method combining chemical modification and high-speed mechanical fusion provided in Example 2 specifically includes the following steps:

[0046] S1, Chemically Modified Silver Powder: Utilizing palmitic acid (C... 16 H 32 O2) was used to coat and modify spherical silver powder to obtain palmitic acid (C 16 H 32 O2) modified spherical silver powder; this silver powder has certain monodispersity, with a D50 range of 1.0-1.3 μm and a D90 of 2.6 μm; palmitic acid (C 16 H 32 O2) and palmitic acid (C 16 H 32 The mass ratio of O2-modified spherical silver powder is 0.5%;

[0047] S2, Physically Modified Silver Powder: Weigh 1000g of palmitic acid (C 16 H 32 O2-modified spherical silver powder was added to the reactor of a high-speed fusion machine for high-speed fusion modification to obtain high-speed fusion modified spherical silver powder; the high-speed fusion modification machine had a frequency of 20Hz, a processing time of 12min, and a processing temperature of 6℃-10℃.

[0048] S3. Modified finished product: The silver powder modified by high-speed fusion is taken out from the fusion machine, sieved and packaged to obtain the composite modified product.

[0049] In the modification process, first weigh out the coating agent palmitic acid (C 16 H 32 O2) was used to chemically modify spherical silver powder to obtain palmitic acid (C 16 H 32 O2) modified spherical silver powder; secondly, palmitic acid (C 16 H 32 O2-modified spherical silver powder was added to the vessel of a high-speed fusion modifier. Modification parameters were then set, and palmitic acid (C2) was modified under high-speed action in the high-speed fusion modifier. 16 H 32O2)-modified spherical silver powder undergoes physical modification treatment to make the modified silver powder structure more compact, the surface smoother and rounder, and the sphericity higher; palmitic acid (C) is added to the reactor of the high-speed fusion modification machine. 16 H 32 O2-modified spherical silver powder undergoes three-dimensional flow under the tilting and high-speed rotation of the rotor. Impact, compressive, and shear forces generated by collisions between the rotor, the wall, and the powder continuously exert stress on the silver powder. The process of micro-powder solidification on the masterbatch surface, accompanied by a composite effect, is repeated, achieving both densification and spheroidization, significantly improving the wettability of the silver powder to organic systems and the thixotropic properties of the slurry.

[0050] Example 3

[0051] The silver powder surface modification method combining chemical modification and high-speed mechanical fusion provided in Example 3 specifically includes the following steps:

[0052] S1, Chemically Modified Silver Powder: Utilizing oleylamine (C 18 H 37 N) was used to coat and modify spherical silver powder to obtain oleylamine (C 18 H 37 N) modified spherical silver powder; this silver powder has certain monodispersity, with a D50 range of 0.9-1.3 μm and a D90 of 2.1 μm; oleylamine (C 18 H 37 N) and oleylamine (C) 18 H 37 The mass ratio of N)-modified spherical silver powder is 0.5%;

[0053] S2, Physically Modified Silver Powder: Weigh 1000g of oleylamine (C 18 H 37 N) The modified spherical silver powder was added into the reactor of a high-speed fusion machine for high-speed fusion modification treatment to obtain high-speed fusion modified spherical silver powder; the high-speed fusion modification machine frequency was 20Hz, the processing time was 20min, and the processing temperature was 6℃-10℃.

[0054] S3. Modified finished product: The spherical silver powder modified by high-speed fusion is taken out from the fusion machine, sieved and packaged to obtain the composite modified product.

[0055] In the modification process, first weigh the coating agent oleylamine (C 18 H 37 N) chemically modified spherical silver powder to obtain oleylamine (C 18 H 37 N) modified spherical silver powder; secondly, oleylamine (C 18 H 37N)-modified spherical silver powder was added to the vessel of a high-speed fusion modifier, and then the modification parameters were set. Under the high-speed action of the high-speed fusion modifier, oleylamine (C) was modified. 18 H 37 The N)-modified spherical silver powder undergoes physical modification treatment to make the modified silver powder structure more compact, the surface smoother and rounder, and the sphericity higher; the oil amine (C) is added to the reactor of the high-speed fusion modification machine. 18 H 37 The modified spherical silver powder forms a three-dimensional flow under the tilting and high-speed rotation of the rotor. The impact, compressive, and shear forces generated by the collisions between the rotor, the wall, and the powder continuously exert force on the silver powder. The process of micro-powder solidification on the surface of the masterbatch, accompanied by the composite effect, is repeated, achieving densification and sphericity at the same time, significantly improving the wettability of the silver powder to the organic system and the thixotropic properties of the slurry.

[0056] Example 4

[0057] The silver powder surface modification method combining chemical modification and high-speed mechanical fusion provided in Example 4 specifically includes the following steps:

[0058] S1, Chemical modification of silver powder: using stearic acid (C 17 H 35 Chemical modification of spherical silver powder with COOH yields stearic acid (C... 17 H 35 The silver powder, modified with COOH, is a near-spherical shape; it exhibits monodispersity with a D50 range of 1.1-1.2 μm and a D90 of 2.4 μm; stearic acid (C 17 H 35 COOH) and stearic acid (C 17 H 35 The mass ratio of COOH-modified spherical silver powder is 0.5%;

[0059] S2, Physical modification of silver powder: Weigh 1000g of stearic acid (C 17 H 35 COOH) was added to the reactor of a high-speed fusion machine to perform high-speed fusion modification treatment on near-spherical silver powder to obtain high-speed fusion modified near-spherical silver powder; the high-speed fusion modification machine frequency was 20Hz, the processing time was 30min, and the processing temperature was 6℃-10℃.

[0060] S3. Modified finished product: The spherical silver powder modified by high-speed fusion is taken out from the fusion machine, sieved and packaged to obtain the composite modified product.

[0061] In the modification process, first weigh out the coating agent stearic acid (C 17 H 35Chemical modification of spherical silver powder with COOH yields stearic acid (C... 17 H 35 Spherical silver powder modified with COOH; secondly, stearic acid (C 17 H 35 The spherical silver powder modified with COOH was added to the vessel of a high-speed fusion modifier. Then, the modification parameters were set, and the stearic acid (C) was modified under high speed in the high-speed fusion modifier. 17 H 35 The spherical silver powder modified with COOH underwent physical modification treatment to make the modified silver powder structure more compact, the surface smoother and rounder, and the sphericity higher; stearic acid (C) was added to the reactor of the high-speed fusion modification machine. 17 H 35 The COOH-modified near-spherical silver powder undergoes a three-dimensional flow under the tilting and high-speed rotation of the rotor. Impact, compressive, and shear forces generated by collisions between the rotor, the wall, and the powder continuously exert stress on the silver powder. The process of micro-powder solidification on the masterbatch surface, accompanied by a composite effect, is repeated, achieving both densification and sphericity, significantly improving the wettability of the silver powder to organic systems and the thixotropic properties of the slurry.

[0062] Comparative Example

[0063] Comparative Example 1

[0064] The silver powder surface modification method provided in Comparative Example 1 specifically includes the following steps:

[0065] S1, Chemically Modified Silver Powder: Using stearic acid (C...) as a coating agent... 17 H 35 Chemical modification of spherical silver powder with COOH yields stearic acid (C... 17 H 35 The silver powder was modified with COOH to form spherical particles; this silver powder exhibited certain monodispersity, with a D50 range of 1.0-1.3 μm and a D90 of 2.4 μm; stearic acid (C 17 H 35 COOH) and stearic acid (C 17 H 35 The mass ratio of COOH-modified spherical silver powder is 0.5%;

[0066] S2, Physical modification of silver powder: Weigh 1000g of stearic acid (C 17 H 35The COOH-modified spherical silver powder was added to the reactor of a high-speed fusion machine for high-speed fusion modification. The specific method of high-speed fusion modification was as follows: first, the high-speed fusion modification machine was used at a frequency of 20Hz, a processing time of 10min, and a processing temperature of 6℃-10℃; then, the frequency of the high-speed fusion modification machine was changed to 40Hz, the processing time was changed to 10min, and the processing temperature was changed to 6℃-10℃; thus, the high-speed fusion modified spherical silver powder was obtained.

[0067] S3. Modified finished product: The spherical silver powder modified by high-speed fusion is taken out from the fusion machine, sieved and packaged to obtain the composite modified product.

[0068] In the modification process, first weigh stearic acid (C 17 H 35 Chemical modification of spherical silver powder with COOH yields stearic acid (C... 17 H 35 Spherical silver powder modified with COOH; secondly, stearic acid (C 17 H 35 The spherical silver powder modified with COOH was added to the vessel of a high-speed fusion modifier. Then, the modification parameters were set, and the stearic acid (C) was modified under high speed in the high-speed fusion modifier. 17 H 35 The spherical silver powder modified with COOH underwent physical modification treatment, resulting in a more compact structure, a smoother and rounder surface, and higher sphericity. Furthermore, the stearic acid (C...) in the reactor of the high-speed fusion modifier... 17 H 35 The COOH-modified near-spherical silver powder undergoes a three-dimensional flow under the tilting and high-speed rotation of the rotor. Impact, compressive, and shear forces generated by collisions between the rotor, the wall, and the powder continuously exert stress on the silver powder. The process of micro-powder solidification on the masterbatch surface, accompanied by a composite effect, is repeated, achieving both densification and sphericity, significantly improving the wettability of the silver powder to organic systems and the thixotropic properties of the slurry.

[0069] Application examples

[0070] The modified silver powder obtained in Examples 1-4 and Comparative Example 1 was used to prepare conductive pastes, and their performance was tested. The specific test results are shown in Table 1, and the specific test contents are as follows:

[0071] 1) The conductive paste is obtained through the following method:

[0072] The conductive paste was prepared by stirring the following components: 86 wt% modified silver powder, 2.5 wt% glass powder, 1.4 wt% aluminum powder, 0.2 wt% acrylic resin, 1.5 wt% thixotropic agent, 8 wt% organic solvent, and 0.4 wt% dispersant.

[0073] 2) Viscosity and stability test

[0074] The viscosity of the conductive paste was tested according to GB / T 17473 "Slurry for Crystalline Silicon Photovoltaic Cells - Rotational Viscometer Method (Arbitration Method)". The test temperature was set at (25±0.5)℃, the rotation speed at 10 r / min, and the torque percentage between 10% and 90%. The viscosity data was read after the reading stabilized.

[0075] The stability test specifically examines the viscosity change of the conductive paste after being placed at 25°C for 24 hours.

[0076] 3) Thixotropic index test

[0077] The test was conducted in accordance with GB / T 17472-2022 "Test Methods for Noble Metal Slurries for Microelectronics Technology", and the viscosity ratio at 5 rpm and 50 rpm was used as the thixotropic index.

[0078] 4) Loose packing density test

[0079] The test was conducted in accordance with GB / T 1479.3-2017 "Metal Powder Loose Packing Density Test Method", specifically using GB / T1479.3-2017 Part 3: Vibrating Funnel Method.

[0080] 5) Tap density test

[0081] The test was conducted in accordance with GB / T 5162-2021 "Metal Powder Tap Density Test Method", with a vibration frequency of 100 times / min to 300 times / min.

[0082] Table 1: Results of the Test Items

[0083]

[0084] To verify the impact of the high-speed fusion modification method on the performance of silver powder, experiments were conducted using multiple embodiments. The experimental results show that the high-speed fusion modification method improves the sphericity, specific surface area, and pore structure of the silver powder, while reducing agglomeration. The modified silver powder exhibits better flowability, stability, and dispersibility in the preparation of silver paste, and significantly improves the thixotropy, recovery, and t50 properties of the silver paste. These experimental data are presented in Table 2.

[0085] Table 2: Comparison of the properties of silver powder and silver paste before and after high-speed fusion modification

[0086]

[0087] To verify the effect of the high-speed fusion modification method on the performance of silver powder, scanning electron microscopy was performed on unmodified silver powder, surface-modified silver powder obtained in Examples 1-4, and comparative examples. The detection results are as follows: Figures 1-6 As shown.

[0088] By comparison Figures 1-6 It can be seen that, Figure 1 Unmodified silver powder particles are irregular in shape, exhibiting a spherical or polyhedral structure with a rough surface and obvious edges; significant agglomeration occurs between particles, forming chain-like or cluster-like aggregates with poor dispersibility; the pore distribution is uneven, with some areas having large pores, which restricts the improvement of tap density. Figure 2-5 The silver powder particles, which combine chemical modification with high-speed mechanical fusion, have rounded edges and almost no sharp corners. The sphericity of the particles is significantly improved to 98%. The chemical coating agent pre-anchors the surface active sites, reducing the energy barrier of subsequent physical fusion, so that the mechanical energy of high-speed fusion is efficiently converted into morphological plastic deformation. Agglomeration is reduced and the boundaries between particles are clear. The chemical modification and high-speed mechanical fusion destroy van der Waals forces and achieve a synergistic effect of "steric hindrance-mechanical deagglomeration". Figure 3 The modified silver powder forms a nanoscale fine grain layer on its surface. The fine grain layer provides high-density grain boundaries, thereby increasing the sintering diffusion rate and shortening t50 to 1-2s. In addition, the fine grain gaps anchor the coating agent molecules, thereby improving inorganic compatibility and reducing viscosity by 44.8%. Figure 4 After modification, the surface of the silver powder has no obvious pits or cracks. The triaxial forces of impact, compression and shear promote the closure of surface micropores. The combination of chemical modification and high-speed mechanical fusion makes the structure of silver powder more compact and reduces the porosity to 35%. Figure 6 Although there is a certain spheroidizing effect, there are still micro-protrusions on the surface and some particles are deformed, resulting in a weaker t50 and viscosity effect than in the example.

[0089] The experimental results effectively demonstrate the improvement effect of the high-speed fusion modification method on silver powder performance, and also verify its application value in the preparation of high-performance silver paste. By adjusting the high-speed fusion modification parameters, specific process and application requirements can be met, providing technical support for the development of the photovoltaic industry.

[0090] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A surface-modified silver powder, characterized by, The surface modified silver powder comprises silver powder particles and a coating agent coated on the surface of the silver powder particles; wherein the surface modified silver powder has a densified structure and a nanoscale surface fine crystal layer formed after chemical modification and physical high-speed fusion treatment.

2. The surface-modified silver powder of claim 1, wherein The mass of the coating agent is 0.1wt%-1.0wt% of the mass of the silver powder particles.

3. The surface-modified silver powder of claim 1, wherein, The particle size of the silver powder particles is 0.3μm-5.0μm.

4. The surface-modified silver powder of claim 1, wherein, The silver powder particles are selected from at least one of spheroid silver powder, spherical silver powder and microcrystalline silver powder.

5. The surface-modified silver powder of claim 1, wherein the surface-modified silver powder has a D50 of 0.1 to 1.0 μιη. The coating agent is a fatty acid compound or an oleylamine compound.

6. The surface-modified silver powder of claim 1, wherein, The coating agent is selected from at least one of a fatty acid compound, an aliphatic compound, an oleic acid compound, a silane coupling agent compound and an amino-containing small molecule compound.

7. A method of producing the surface-modified silver powder according to claim 1, characterized by, The method comprises the following steps: The silver powder particles are surface modified with a coating agent to obtain chemically modified silver powder; The chemically modified silver powder is subjected to high-speed fusion treatment to obtain the surface modified silver powder.

8. The production method according to claim 7, characterized by, In the high-speed fusion treatment step, the modification temperature is 15℃-80℃, the modification frequency is 10Hz-60Hz and the modification time is 3min-120min.

9. An electrically conductive silver paste, characterized in that, The composition comprises the following components by mass fraction: 85wt%-90wt% of the surface modified silver powder according to claim 1, 2.0wt%-3.0wt% of glass powder, 1.0wt%-2.0wt% of aluminum powder, 0.1wt%-0.5wt% of acrylic resin, 1.0wt%-2.0wt% of thixotropic agent, 5wt%-10wt% of organic solvent and 0.1wt%-0.5wt% of dispersant.

10. Use of the conductive silver paste according to claim 9 in the preparation of a front material of a TOPCon cell.

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