Preparation method of silver-coated glass powder for solar cell silver paste

Abstract

The invention relates to the technical field of solar cell materials, and discloses a preparation method of silver-coated glass powder for solar cell silver paste, which comprises the following steps: S1, glass powder core preparation: raw material mixing: respectively weighing a phase A and a phase B, and ball-milling and mixing; carrying out gradient melting; crushing and grading; s2, plasma activating treatment pretreatment: putting the prepared glass powder core body into a citric acid solution, and carrying out ultrasonic cleaning to remove pollutants on the surface of the glass powder; fluidized bed activation; performing plasma treatment; performing passivation protection; s3, microfluidics-ultrasonic coupling coating; S4, a post-treatment process: washing and drying; heat treatment; and screening and packaging: screening the annealed powder through a vibrating screen to obtain the silver-coated glass powder. The preparation method of the silver-coated glass powder for the solar cell silver paste is relatively low in cost and relatively low in pollution.

Description

Technical Field

[0001] This invention relates to the field of solar cell materials technology, specifically to a method for preparing silver-coated glass powder for solar cell silver paste. Background Technology

[0002] As a core conductive material in photovoltaic cells, silver paste directly affects the photoelectric conversion efficiency and long-term reliability of the cells. Silver-coated glass powder, a key functional component of silver paste, plays a triple role in the sintering process: etching the passivation layer, promoting ohmic contacts, and constructing the conductive network. Currently, the mainstream production process is based on a three-step technology (roughening-activation-silver coating) developed by Hunan Weineng New Materials in 2011. This technology uses a roughening liquid... Treatment and activation of sensitizing solution The process involves treatment, followed by reduction of the deposited silver layer in a silver nitrate solution. However, this process suffers from three major bottlenecks: Insufficient uniformity of coating: The fluid dynamics in traditional stirred reactors (as described in patent CN201110200609.X) are not uniform, resulting in large fluctuations in the silver layer coverage on the glass powder surface (typical value 65-80%), and a wide distribution of silver particle size (50-500nm), leading to poor uniformity of silver film migration during sintering.

[0003] Glass powder has a single function: most existing glass powders are single-component systems (such as...) The system cannot simultaneously meet the dual requirements of TOPCON batteries for acetic acid corrosion resistance (requiring a mass loss rate of <0.5%) and low-temperature sintering characteristics (softening point must be ≤550℃).

[0004] The reduction process is highly polluting: chemical reduction methods require the use of highly toxic reducing agents such as formaldehyde or hydrazine hydrate, generating 3-5 tons of cyanide-containing wastewater per ton of product, and leaving residual sulfur. It will catalyze the oxidation of the silver layer. Summary of the Invention

[0005] Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a method for preparing silver-coated glass powder for solar cell silver paste, which achieves uniform coating, lower cost, and less pollution.

[0006] Technical solution To achieve the above objectives, the present invention provides the following technical solution: a method for preparing silver-coated glass powder for solar cell silver paste, comprising the following steps: S1. Preparation of glass powder nuclei: Raw material mixing: First weigh phase A raw material, then weigh phase B raw material, and then ball mill phase A and phase B together for 2 hours (200 rpm, zirconium balls:material = 3:1). The composition of phase A is as follows: 35 parts by weight 30 parts by weight 12 parts by weight 4.5 parts by weight 1.5 parts by weight; The composition of phase B is as follows: 20 parts by weight 18 parts by weight 10 parts by weight 2 parts by weight; Gradient melting: The mixed raw materials are placed in a corundum crucible and melted for 2 hours, then cooled to 800℃ and held for 30 minutes, followed by the introduction of... Protect against oxidation; Phase separation control: with The molten material is water-quenched to room temperature at a certain rate to obtain a phase-separated glass. Crushing and Classification: First, a jaw crusher is used to coarsely crush the phase-separated glassy phases, and then a fluidized bed air jet mill is used to further pulverize it. Finally, a cyclone classifier is used to remove the particle size. The particles were used to obtain glass powder nuclei; S2. Plasma activation treatment Pretreatment: The prepared glass powder nucleus is placed in In a citric acid solution, at a power of 300W and a frequency Under these conditions, ultrasonic cleaning is performed for 20 minutes to remove contaminants from the glass powder surface; Fluidized bed activation: Pretreated glass powder is loaded into a quartz reaction chamber, and the chamber is evacuated to reduce the pressure inside the chamber to a minimum. Then pass through A 9:1 volume ratio of mixed gas was applied until the working pressure inside the reaction chamber reached [the required level]. ; Plasma processing: Turn on the radio frequency power supply, power density The processing time is 8 minutes, which generates ≡Si• free radicals on the surface; Passivation protection: 0.5% vinyltrimethoxysilane vapor is introduced to form a protective film on the free radical surface; S3. Microfluidic-ultrasonic coupling coating Preparation of silver solution: Prepare a 0.25 mol / L silver nitrate solution, then add 0.1 wt% polyvinylpyrrolidone (PVP). )and Stir well to obtain silver solution; Preparation of reducing solution: Mix 0.3 mol / L ascorbic acid, 0.1 mol / L glucose and 0.05% sodium dodecyl sulfate evenly to prepare the reducing solution; Microfluidic coating: Silver solution and reducing solution are pumped into the microreactor at a volume ratio of 1:3. The temperature of the reaction zone is 60℃ and the pulse period is 1s (0.3s on / 0.7s off) to carry out the microfluidic coating reaction. Ultrasonic-enhanced deposition: Powder that has undergone preliminary microfluidic coating is transferred into an electrochemical bath, where the bath solution... concentration Apply Power density Ultrasound and duty cycle 20%, current density A pulsed current was applied for 30 minutes to achieve ultrasonic-enhanced deposition. Membrane separation and recovery: The effluent from the electrochemical cell is filtered through a 0.1μm ceramic membrane, with a silver ion rejection rate of >99.5%. The concentrate is then returned to the silver solution preparation step to achieve the recycling of silver ions. S4. Post-processing steps Washing and drying: The powder coated by microfluidic-ultrasonic coupling was washed by centrifugation with an ethanol-water mixture (volume ratio 1:1). Centrifuge at 1000 rpm for 10 minutes, repeat washing, and then vacuum dry at 60°C for 3 hours; Heat treatment: Place the dried powder in... Annealing was performed at 350°C in a 95:5 volume ratio atmosphere to eliminate internal stress in the powder. Sieving and Packaging: The annealed powder is sieved through a 500-mesh vibrating screen to obtain a particle size of 1.5 mm. The silver-coated glass powder has a silver layer coverage of ≥95%.

[0007] Furthermore, in S1, the melting temperature during the gradient melting process is 1250°C.

[0008] Further, in S1, the crushing and classification process involves coarsely crushing the phase-separated glass body to... .

[0009] Furthermore, in S2, the fluidized bed processing chamber is made of quartz material, has a diameter of 200mm, a powder residence time of 5-10 minutes, and a temperature control of 40-45℃. Furthermore, in step S2, plasma processing involves turning on the radio frequency power supply and adjusting the frequency... ,power Adjustable, equipped with Mixed air path and The ratio is 9:1.

[0010] Furthermore, in S3, the microreactor employs a Tesla valve structure channel (width × depth = 500). ).

[0011] Furthermore, in step S4, washing and drying: washing 3 times.

[0012] Furthermore, in step S4, the heat treatment and annealing time is 30 minutes.

[0013] Beneficial technical effects 1. Design of a two-phase separated glass core structure Technological Breakthrough: A two-phase structure of "high-lead tellurium phase + zinc borosilicate phase" was achieved through... Interface modifiers induce the formation of a nano-interpenetrating network. Compared to single-phase glass powder (CN 119285239 A), this structure exhibits staged melting characteristics during sintering: phase A melts first at 520℃ to drive the flow of the silver film, while phase B melts at 580℃ to provide etching control.

[0014] 2. Solution Acetic acid corrosion of batteries and Layer-by-layer etching contradiction: in the B phase The network provides excellent acid resistance (acetic acid weight loss rate) Traditionally 0.8%, while phase A ensures low-temperature fluidity. After passing 3000 hours of double 85 testing, the weld pull retention rate of the battery module is >95%.

[0015] 3. Silver coverage increased from 75±8% in the traditional process to 98±1%, and the silver layer thickness fluctuation range (CV value) decreased from 25% to 8%. After sintering, the silver grain size distribution narrowed (1.5±0.3μm vs. traditional 0.8-5μm), and the contact resistance decreased to [missing value]. (Tradition ).

[0016] 4. The combination of piezoelectric ultrasonic cavitation and pulsed electrochemistry generates periodic cavitation bubble collapse (local temperature) in a 28kHz ultrasonic field. ,pressure This drives the directional deposition of silver ions, while simultaneously utilizing the cavitation impact effect to densify the silver layer. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1 A method for preparing silver-coated glass powder for solar cell silver paste includes the following steps: S1. Preparation of glass powder nuclei: Raw material mixing: First weigh phase A raw material, then weigh phase B raw material, and then ball mill phase A and phase B together for 2 hours (200 rpm, zirconium balls:material = 3:1). The composition of phase A is as follows: 35 parts by weight 30 parts by weight 12 parts by weight 4.5 parts by weight 1.5 parts by weight; The composition of phase B is as follows: 20 parts by weight 18 parts by weight 10 parts by weight 2 parts by weight; Gradient melting: The mixed raw materials are placed in a corundum crucible and melted at 1250℃ for 2 hours, then cooled to 800℃ and held for 30 minutes, and then... Protect against oxidation; Phase separation control: The molten material is water quenched to room temperature at a rate of 50℃ / s to obtain a phase-separated glass body; Crushing and grading: First, a jaw crusher is used to coarsely crush the phase-separated glassy phases to... Then, it is pulverized to a fine powder using a fluidized bed jet mill. =1.2μm, and finally a cyclone classifier was used to remove particles with a diameter >3μm to obtain glass powder nuclei; S2. Plasma activation treatment Pretreatment: The prepared glass powder core was placed in a 0.1 mol / L citric acid solution and subjected to a power of 300 W and a frequency of Under these conditions, ultrasonic cleaning is performed for 20 minutes to remove contaminants from the glass powder surface; Fluidized bed activation: Pretreated glass powder is loaded into a quartz reaction chamber, and the chamber is evacuated to reduce the pressure inside the chamber to a minimum. Then pass through A 9:1 volume ratio of mixed gas was applied until the working pressure inside the reaction chamber reached [the required level]. ; Plasma processing: Turn on the radio frequency power supply, power density The processing time is 8 minutes, which allows the surface to form Free radicals; Passivation protection: 0.5% vinyltrimethoxysilane vapor is introduced to form a protective film on the free radical surface; S3. Microfluidic-ultrasonic coupling coating Silver solution preparation: preparation silver nitrate solution, then add to it Polyvinylpyrrolidone and Stir well to obtain silver solution; Preparation of reducing solution: ascorbic acid, Glucose and 0.05% sodium dodecyl sulfate were mixed evenly to prepare a reducing solution; Microfluidic coating: Silver solution and reducing solution are pumped into the microreactor at a volume ratio of 1:3. The temperature of the reaction zone is 60℃ and the pulse period is 1s (0.3s on / 0.7s off) to carry out the microfluidic coating reaction. Ultrasonic-enhanced deposition: Powder that has undergone preliminary microfluidic coating is transferred into an electrochemical bath, where the bath solution... concentration An ultrasonic wave of 28 kHz with a power density of 50 W / L and a duty cycle of 20% with a current density of 100% were applied. A pulsed current was applied for 30 minutes to achieve ultrasonic-enhanced deposition. Membrane separation and recovery: The effluent from the electrochemical cell is separated by... The ceramic membrane is used for filtration, with a silver ion rejection rate of >99.5%. The concentrate is then returned to the silver solution preparation step to achieve the recycling of silver ions. S4. Post-processing steps Washing and drying: The powder coated by microfluidic-ultrasonic coupling was washed by centrifugation with an ethanol-water mixture (volume ratio 1:1). Centrifuge at 1000 rpm for 10 minutes, repeat washing 3 times, and then vacuum dry at 60°C for 3 hours; Heat treatment: Place the dried powder in... Annealing at 350°C for 30 minutes in a 95:5 (volume ratio) atmosphere to eliminate internal stress in the powder; Sieving and Packaging: The annealed powder is sieved through a 500-mesh vibrating screen to obtain silver-coated glass powder with a particle size of 1.5±0.5μm and a silver layer coverage of ≥95%.

[0019] In S2, the fluidized bed processing chamber is made of quartz material, has a diameter of 200mm, a powder residence time of 5 minutes, and a temperature control of 40℃. In step S2, plasma processing involves turning on the radio frequency power supply and adjusting the frequency. Equipped Mixed air intake (ratio 9:1).

[0020] In S3, the microreactor employs a Tesla valve structure channel (width × depth = ).

[0021] The TOPCON back silver paste prepared from the silver-coated glass powder obtained in this invention, under standard process conditions (screen printing + sintering at 780℃), reduces the open-circuit voltage of the battery cell ( Upgraded to (Tradition The fill factor (FF) reaches 83.5% (compared to 81.2% in the traditional method), and the photoelectric conversion efficiency exceeds 26.2% (compared to 25.0% in the traditional method).

[0022] Process environmental innovation: Elimination of formaldehyde use (reducing highly toxic waste liquid by 3.5 tons per ton of product), silver ion recycling rate ≥99.5%, and energy consumption reduced by 40% (plasma activation replaces high-temperature heat treatment).

[0023] Significant cost-effectiveness: Although it increases the cost of preparing duplex glass powder, the overall silver consumption is reduced and the yield is improved, resulting in a decrease in the overall cost of silver paste.

[0024] Completely replaces toxic reducing agents such as formaldehyde, reducing wastewater COD to [a lower level]. (Traditional Craftsmanship) The silver layer bonding strength is increased by 2 times (critical load in scratch test). Traditional 6N), and silver utilization rate increased from 85% to 99.5%.

[0025] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0026] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0027] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments.

Claims

1. A method for preparing silver-coated glass powder for solar cell silver paste, characterized in that, Includes the following steps: S1. Preparation of glass powder nuclei: Raw material mixing: First weigh phase A raw material, then weigh phase B raw material, and then ball mill and mix phase A and phase B. The composition of phase A is as follows: 35 parts by weight 30 parts by weight 12 parts by weight 4.5 parts by weight 1.5 parts by weight; The composition of phase B is as follows: 20 parts by weight 18 parts by weight 10 parts by weight 2 parts by weight; Gradient melting: The mixed raw materials are placed in a corundum crucible for melting, cooled, and then... Protect against oxidation; Phase separation control: The molten material is water-quenched to room temperature to obtain a phase-separated glass body; Crushing and Classification: First, a jaw crusher is used to coarsely crush the phase-separated glassy phases, then a fluidized bed jet mill is used to pulverize it, and finally a cyclone classifier is used to remove particle size. The particles were used to obtain glass powder nuclei; S2. Plasma activation treatment Pretreatment: The prepared glass powder core is placed in citric acid solution and ultrasonically cleaned to remove contaminants from the surface of the glass powder; Fluidized bed activation: Pretreated glass powder is loaded into a quartz reaction chamber, the chamber is evacuated to reduce the pressure, and then... Mixed gas until the working pressure inside the reaction chamber reaches ; Plasma treatment: Turn on the radio frequency power supply to generate ≡Si• free radicals on the surface; Passivation protection: Vinyltrimethoxysilane vapor is introduced to form a protective film on the free radical surface; S3. Microfluidic-ultrasonic coupling coating Preparation of silver nitrate solution: Prepare a silver nitrate solution, then add polyvinylpyrrolidone and... Stir well to obtain silver solution; Preparation of reducing solution: Mix ascorbic acid, glucose, and sodium dodecyl sulfonate evenly to obtain a reducing solution; Microfluidic coating: Silver solution and reducing solution are pumped into a microreactor in a specific volume ratio to carry out a microfluidic coating reaction; Ultrasonic Enhanced Deposition: Powder that has undergone preliminary microfluidic coating is transferred into an electrochemical tank for processing to achieve ultrasonic enhanced deposition; Membrane separation and recovery: The effluent from the electrochemical cell is filtered through a ceramic membrane, and the concentrate is returned to the silver solution preparation step to achieve the recycling of silver ions; S4. Post-processing steps Washing and drying: The powder coated by microfluidic-ultrasonic coupling is washed by centrifugation with an ethanol-water mixture, centrifuged, washed repeatedly, and then vacuum dried; Heat treatment: Place the dried powder in... Annealing is performed in an atmosphere to eliminate internal stress in the powder. Screening and Packaging: The annealed powder is screened through a vibrating screen to obtain silver-coated glass powder.

2. The method for preparing silver-coated glass powder for solar cell silver paste according to claim 1, characterized in that, In S1, the melting temperature during the gradient melting process is 1250℃.

3. The method for preparing silver-coated glass powder for solar cell silver paste according to claim 1, characterized in that, In step S1, the crushing and grading process involves coarsely crushing the phase-separated glass body to... .

4. The method for preparing silver-coated glass powder for solar cell silver paste according to claim 1, characterized in that, In S2, the fluidized bed processing chamber is made of quartz material, with a diameter of 200mm, a powder residence time of 5-10 minutes, and a temperature control of 40-45℃.

5. The method for preparing silver-coated glass powder for solar cell silver paste according to claim 1, characterized in that, In step S2, plasma processing involves turning on the radio frequency power supply and adjusting the frequency. Power adjustable from 0-500W, equipped with Mixed air path, and The ratio is 9:

1.

6. The method for preparing silver-coated glass powder for solar cell silver paste according to claim 1, characterized in that, In S3, the microreactor employs a Tesla valve structure channel, with the Tesla valve structure channel width × depth = .

7. The method for preparing silver-coated glass powder for solar cell silver paste according to claim 1, characterized in that, In step S4, washing and drying: washing 3 times.

8. The method for preparing silver-coated glass powder for solar cell silver paste according to claim 1, characterized in that, In step S4, the heat treatment and annealing time is 30 minutes.