CN115483341A - Preparation method of a flexible N-type nylon-based silver selenide thermoelectric film - Google Patents

Abstract

The invention discloses a preparation method of a flexible N-type nylon-based silver selenide thermoelectric film, which comprises the steps of synthesizing silver selenide particles by a solvothermal method, uniformly dispersing the silver selenide particles in ethylene glycol, uniformly dripping the silver selenide particles on a glass fiber filter membrane, and performing discharge plasma sintering (SPS) treatment to obtain a uniform and compact flexible nylon-based silver selenide film. The thin film prepared by the method has excellent thermoelectric performance, the adopted discharge plasma sintering (SPS) process can regulate and control the microscopic morphology and the carrier transmission characteristic of the thin film, the silver content in the thin film is reduced, and an ordered fiber structure is formed, so that the carrier concentration is reduced, the carrier mobility is improved, the Seebeck coefficient and the conductivity are simultaneously enhanced, the method has simple process, short preparation period, safety and no pollution, and the obtained thin film has excellent thermoelectric performance and good flexibility.

Description

Preparation method of a flexible N-type nylon-based silver selenide thermoelectric film

Technical field:

The invention relates to the technical field of new energy materials, in particular to a method for preparing a flexible N-type nylon-based silver selenide thermoelectric film.

Background technique:

At present, with the rise of the Internet of Things era, products such as wearable electronic devices have achieved rapid development, and they have broad application prospects in medical equipment, environmental monitoring, smart clothing and other fields. In recent years, the trend of miniaturization and flexibility of wearable electronic devices has promoted the research progress of flexible thermoelectric thin film devices. Flexible thermoelectric thin film materials have the characteristics of light weight, good mechanical flexibility, and low cost, which provide potential for the development and application of wearable electronic devices in the future.

Silver selenide has intrinsically high electrical conductivity and Seebeck coefficient at room temperature, and has excellent thermoelectric performance, which is expected to meet the requirements of flexible device applications. However, limited by the preparation method, the thermoelectric performance of the flexible film prepared by cold pressing, hot pressing, printing, thermal evaporation and other methods is much smaller than that of the silver selenide-based bulk. Therefore, more effective techniques should be explored to prepare silver selenide-based thin films with excellent performance and good flexibility.

Invention content:

The purpose of the present invention is to provide a preparation method of flexible N-type nylon-based silver selenide thermoelectric thin film, which firstly synthesizes silver selenide particles by solvothermal method, then uniformly disperses them in ethylene glycol, and then uniformly drop-coats them on a glass fiber filter. On the film, after discharge plasma sintering (SPS) treatment, a uniform and dense flexible nylon-based silver selenide film is obtained, with excellent thermoelectric properties. This method not only reduces the silver content in the film, but also forms an ordered fiber structure, thereby The carrier concentration is reduced and the carrier mobility is increased, so that the Seebeck coefficient and conductivity are simultaneously enhanced. The method has the advantages of simple process, short preparation period, safety and no pollution, and the obtained thin film has excellent thermoelectric performance and good flexibility.

The present invention is achieved through the following technical solutions:

A preparation method of a flexible N-type nylon-based silver selenide thermoelectric film, the method comprising the following steps:

(1) Dissolve silver nitrate and selenium powder with a molar ratio of (2.1-2.5): 1 in ethylenediamine respectively, pour it into the reaction kettle after stirring, and place the reaction kettle in a blast drying oven at 180°C for 5 hours , the obtained product was alternately centrifuged and washed with deionized water and ethanol for 2 to 3 times, and then ultrasonically dispersed the washed silver selenide particles into 10 mL of ethylene glycol to obtain a uniform silver selenide dispersion; The concentration is 25-35mg/mL;

(2) Under the assisted condition of vacuum filtration, the silver selenide dispersion that step (1) is obtained is evenly drip-coated on the glass fiber filter membrane, and the drip coating amount of the silver selenide dispersion is 1-2mL/cm ^2. After the liquid is drained, dry it in a vacuum oven at 60°C to obtain a silver selenide film adhered to the glass fiber filter membrane;

(3) The silver selenide film adhered to the glass fiber filter membrane obtained in step (2) is placed between two nylon filter membranes, and formed by spark plasma sintering (SPS) at a sintering temperature of 100-200°C , the sintering time is 1-9min, the pressure is 30-50MPa, then first remove the nylon filter membrane on the back of the glass fiber filter membrane, and then wipe off the glass fiber filter membrane fragments on the surface of the silver selenide film to obtain a flexible N-type nylon-based selenide Silver thermoelectric thin film.

Preferably, the molar ratio of silver nitrate and selenium powder in step (1) is 2.3:1, and the concentration of silver selenide is 28-32 mg/mL.

Preferably, the drop coating amount of the silver selenide dispersion in step (2) is 1.2 mL/cm ² .

Preferably, the sintering temperature of the spark plasma sintering (SPS) process in step (3) is 130-200° C., the sintering time is 1-7 min, and the pressure is 30 MPa.

The beneficial effects of the present invention are as follows:

1) The silver selenide particles synthesized by the solvothermal method in the present invention can be uniformly dispersed in ethylene glycol, and can be uniformly drip-coated on the glass fiber filter membrane, and subsequently processed by discharge plasma sintering (SPS) to obtain uniform and dense flexible nylon-based silver selenide films.

2) For the first time, the flexible N-type nylon-based silver selenide thermoelectric thin film was prepared by using the spark plasma sintering (SPS) process. Through the optimization of the sintering process, the control of the microscopic morphology and silver content of the film was realized, and the silver content in the film was reduced. , forming an ordered fiber structure, thereby reducing the carrier concentration and increasing the carrier mobility, so that the Seebeck coefficient and electrical conductivity are simultaneously enhanced, thereby achieving a further improvement in thermoelectric performance. The method has simple process, short preparation cycle, safety, pollution-free, simple and controllable, and compared with cold pressing, hot pressing, printing, thermal evaporation and other preparation methods, the film prepared by the present invention has more excellent thermoelectric performance and better mechanical flexibility.

Description of drawings:

Fig. 1 is the surface scanning electron micrograph of the silver selenide thin film adhered on the glass fiber filter membrane that step (2) of embodiment 1 of the present invention obtains.

Fig. 2 is a scanning electron micrograph of the surface of the flexible N-type nylon-based silver selenide thermoelectric thin film obtained in step (3) of Example 1 of the present invention.

Fig. 3 is a cross-sectional scanning electron micrograph of the flexible N-type nylon-based silver selenide thermoelectric thin film obtained in Example 1 of the present invention.

FIG. 4 shows the relationship between the electrical conductivity and power factor of the flexible N-type nylon-based silver selenide thermoelectric thin film obtained in Example 1 of the present invention as a function of temperature.

Fig. 5 is the relationship between the resistance and the bending radius of the flexible N-type nylon-based silver selenide thermoelectric thin film obtained in Example 1 of the present invention.

6 is a cross-sectional scanning electron micrograph of the silver selenide film adhered to the glass fiber filter membrane obtained in Comparative Example 1 of the present invention.

FIG. 7 shows the relationship between the electrical conductivity and power factor of the flexible N-type nylon-based silver selenide thermoelectric thin film obtained in Comparative Example 1 of the present invention as a function of temperature.

FIG. 8 shows the relationship between the electrical conductivity and power factor of the flexible N-type nylon-based silver selenide thermoelectric thin film obtained in Example 2 of the present invention as a function of temperature.

detailed description:

The following is a further description of the present invention, rather than a limitation of the present invention.

Example 1: A method for preparing a flexible N-type nylon-based silver selenide thermoelectric film

(1) Dissolve silver nitrate and selenium powder with a molar ratio of 2.3:1 in 7.5mL and 10mL of ethylenediamine respectively, stir for 30min, pour into a 25mL reaction kettle, and place the reaction kettle in a blast drying oven React at 180°C for 5 hours; the obtained product was alternately centrifuged and washed with deionized water and ethanol for 2 to 3 times, and then ultrasonically dispersed the washed silver selenide particles into 10 mL of ethylene glycol to obtain a uniform silver selenide dispersion; The concentration of silver selenide is 29mg/mL;

(2) Under the assisted condition of vacuum suction, the silver selenide dispersion liquid obtained in step (1) is evenly drip-coated on the glass fiber filter membrane of 20mm*5mm, and the drip coating amount of the silver selenide dispersion liquid is 1.2 mL/cm ² , after the liquid was drained, it was dried in a vacuum oven at 60°C to obtain a silver selenide film adhered to the glass fiber filter membrane. The scanning electron microscope photo of the film surface is shown in Figure 1;

(3) Place the silver selenide thin film adhered on the glass fiber filter membrane that step (2) obtains between two nylon filter membranes, through spark plasma sintering (SPS) molding, sintering temperature is 200 ℃, sintering The time is 5min and the pressure is 30MPa. After that, remove the nylon filter membrane on the back of the glass fiber filter membrane, and then wipe off the glass fiber filter membrane fragments on the surface of the silver selenide film to obtain a flexible N-type nylon-based silver selenide thermoelectric film. Figure 2 shows the scanning electron microscope photo of its section, and Figure 3 shows the scanning electron microscope picture of its section. Figure 4 shows the electrical conductivity and power factor. Figure 5 shows the relationship between resistance and bending radius. It can be seen from Figures 1 and 2 that, through the simultaneous action of temperature and pressure in the spark plasma sintering (SPS) process, the silver selenide particles are squeezed and piled together, the grains grow, and the film becomes denser, thus having a higher conductivity. It can be seen from Figure 4 that the silver selenide thermoelectric thin film attached to the nylon substrate has better mechanical flexibility. When the bending radius is 2.5 mm, the resistance of the thin film remains almost unchanged, indicating that the prepared thin film is more flexible.

Comparative example 1:

(1) Dissolve silver nitrate and selenium powder with a molar ratio of 2.3:1 in 7.5mL and 10mL of ethylenediamine respectively, stir for 30min, pour into a 25mL reaction kettle, and place the reaction kettle in a blast drying oven React at 180°C for 5 hours; the obtained product was alternately centrifuged and washed with deionized water and ethanol for 2 to 3 times, and then ultrasonically dispersed the washed silver selenide particles into 10 mL of ethylene glycol to obtain a uniform silver selenide dispersion; The concentration of silver selenide is 29mg/mL;

(2) Under the assisted condition of vacuum suction, the silver selenide dispersion liquid obtained in step (1) is evenly drip-coated on the glass fiber filter membrane of 20mm*5mm, and the drip coating amount of the silver selenide dispersion liquid is 1.2 mL/cm ² , after the liquid is drained, dry it in a vacuum oven at 60°C to obtain a silver selenide film adhered to the glass fiber filter membrane;

(3) Place the silver selenide thin film adhered on the glass fiber filter membrane that step (2) obtains between two nylon filter membranes, use a tablet press to form cold press molding under a pressure of 30MPa, then remove the glass The nylon filter membrane on the back of the fiber filter membrane, and then wipe off the glass fiber filter membrane fragments on the surface of the silver selenide film to obtain a flexible N-type nylon-based silver selenide thermoelectric film. The scanning electron micrograph of its section is as shown in Figure 6 (Fig. 6 compares with Fig. 3 in embodiment 1 and can know: through spark plasma sintering (SPS) processing causes the composition and the appearance of thin film to have changed, formed orderly The fiber texture changes the carrier transport characteristics of the silver selenide thin film), and its conductivity and power factor are shown in Figure 7.

It can be seen from Example 1 and Comparative Example 1 that the plastic deformation of the product obtained in Example 1 changes the carrier concentration and mobility of the film, so the conductivity and power factor are significantly enhanced, and it has more application prospects.

Comparative example 2:

The synthetic method in the reference "Ultrahigh Performance of n-Type Ag ₂ Se Films for FlexibleThermoelectric Power Generators" (Cong Jiang and Yufei Ding, DOI: 10.1021/acsami.9b21069) prepares silver selenide nanowires, and then sinters them according to the present invention Methods A nylon-based silver selenide thermoelectric thin film was prepared.

(1) Add pure selenium dioxide (0.1 g) and β-cyclodextrin (0.1 g) into a beaker containing 10 mL of deionized water, stir for 10 min to obtain a clear solution, and immediately pour it into another beaker under continuous stirring In a beaker containing ascorbic acid solution (20 mL, 0.028M), the mixture rapidly changed from colorless to yellow. A brick-red suspension formed immediately afterwards, indicating the formation of amorphous selenium. After reacting for 4 h, the product was collected by alternate centrifugation with deionized water and ethanol, and then redispersed in ethanol and aged for 2 h without stirring. During this process, the mixture turned from brick red to metallic gray, resulting in selenium nanowires.

(2) Using 20 mL of ethylene glycol dispersion of selenium nanowires as a template, react with silver nitrate at 40°C for 2 h, the molar ratio of silver nitrate and selenium powder is 2.3:1, and then collect by centrifugation to obtain silver selenide nanostructures , and then disperse the silver selenide nanowires in 10ml of absolute ethanol.

(3) Under the assisted condition of vacuum suction filtration, the silver selenide nanowire dispersion liquid that will obtain is drop-coated on the glass fiber filter membrane of 20mm*5mm evenly, and the drop-coating amount of silver selenide dispersion liquid is 1.2mL/ cm ² , after the liquid was drained, it was dried in a vacuum oven at 60°C to obtain a silver selenide film adhered to a glass fiber filter membrane.

(4) The obtained silver selenide thin film adhered on the glass fiber filter membrane is placed between two nylon filter membranes, and is formed by spark plasma sintering (SPS). The sintering temperature is 200°C, the sintering time is 5min, and the pressure Then remove the nylon filter membrane on the back of the glass fiber filter membrane, and then wipe off the glass fiber filter membrane fragments on the surface of the silver selenide film to obtain a flexible N-type nylon-based silver selenide thermoelectric film. Its power factor is only 471.03μW/(mK ² ) at 30°C. The silver selenide dispersion liquid prepared by this method has poor dispersibility, and the finally prepared silver selenide thin film has uneven thickness and large resistance, so its performance is poor.

From Example 1 and Comparative Example 2, it can be seen that in Example 1, because the silver selenide particles synthesized by the solvothermal method can be uniformly dispersed in ethylene glycol, it can be uniformly drip-coated on the glass fiber filter membrane, and then through discharge Plasma sintering (SPS) treatment can obtain a uniform and dense nylon-based silver selenide film with excellent thermoelectric properties and good flexibility.

Example 2:

(1) Dissolve silver nitrate and selenium powder with a molar ratio of 2.3:1 in 7.5mL and 10mL of ethylenediamine respectively, stir for 30min, pour into a 25mL reaction kettle, and place the reaction kettle in a blast drying oven React at 180°C for 5 hours; the obtained product was alternately centrifuged and washed with deionized water and ethanol for 2 to 3 times, and then ultrasonically dispersed the washed silver selenide particles into 10 mL of ethylene glycol to obtain a uniform silver selenide dispersion; The concentration of silver selenide is 29mg/mL;

(2) Under the assisted condition of vacuum suction, the silver selenide dispersion liquid obtained in step (1) is evenly drip-coated on the glass fiber filter membrane of 20mm*5mm, and the drip coating amount of the silver selenide dispersion liquid is 1.2 mL/cm ² , after the liquid is drained, dry it in a vacuum oven at 60°C to obtain a silver selenide film adhered to the glass fiber filter membrane;

(3) Place the silver selenide thin film adhered on the glass fiber filter membrane that step (2) obtains between two nylon filter membranes, through spark plasma sintering (SPS) molding, sintering temperature is 130 ℃, sintering The time is 1min, the pressure is 30MPa, and then the nylon filter membrane on the back of the glass fiber filter membrane is removed first, and then the glass fiber filter membrane fragments on the surface of the silver selenide film are wiped off to obtain a flexible N-type nylon-based silver selenide thermoelectric film. Its conductivity and power factor are shown in Figure 8.

Example 3:

(1) Dissolve silver nitrate and selenium powder with a molar ratio of 2.3:1 in 7.5mL and 10mL of ethylenediamine respectively, stir for 30min, pour into a 25mL reaction kettle, and place the reaction kettle in a blast drying oven React at 180°C for 5 hours; the obtained product was alternately centrifuged and washed with deionized water and ethanol for 2 to 3 times, and then ultrasonically dispersed the washed silver selenide particles into 10 mL of ethylene glycol to obtain a uniform silver selenide dispersion; The concentration of silver selenide is 29mg/mL;

(2) Under the assisted condition of vacuum suction, the silver selenide dispersion liquid obtained in step (1) is evenly drip-coated on the glass fiber filter membrane of 20mm*5mm, and the drip coating amount of the silver selenide dispersion liquid is 1.2 mL/cm ² , after the liquid is drained, dry it in a vacuum oven at 60°C to obtain a silver selenide film adhered to the glass fiber filter membrane;

(3) Place the silver selenide thin film adhered on the glass fiber filter membrane that step (2) obtains between two nylon filter membranes, through spark plasma sintering (SPS) molding, sintering temperature is 150 ℃, sintering The time is 1min, the pressure is 30MPa, and then the nylon filter membrane on the back of the glass fiber filter membrane is removed first, and then the glass fiber filter membrane fragments on the surface of the silver selenide film are wiped off to obtain a flexible N-type nylon-based silver selenide thermoelectric film. Its power factor at 30°C is 2920.01μW/(mK ² ).

Example 4:

(1) Dissolve silver nitrate and selenium powder with a molar ratio of 2.3:1 in 7.5mL and 10mL of ethylenediamine respectively, stir for 30min, pour into a 25mL reaction kettle, and place the reaction kettle in a blast drying oven React at 180°C for 5 hours; the obtained product was alternately centrifuged and washed with deionized water and ethanol for 2 to 3 times, and then ultrasonically dispersed the washed silver selenide particles into 10 mL of ethylene glycol to obtain a uniform silver selenide dispersion; The concentration of silver selenide is 29mg/mL;

(2) Under the assisted condition of vacuum suction, the silver selenide dispersion liquid obtained in step (1) is evenly drip-coated on the glass fiber filter membrane of 20mm*5mm, and the drip coating amount of the silver selenide dispersion liquid is 1.2 mL/cm ² , after the liquid is drained, dry it in a vacuum oven at 60°C to obtain a silver selenide film adhered to the glass fiber filter membrane;

(3) Place the silver selenide thin film adhered on the glass fiber filter membrane that step (2) obtains between two nylon filter membranes, through spark plasma sintering (SPS) molding, sintering temperature is 200 ℃, sintering The time is 1min, the pressure is 30MPa, and then the nylon filter membrane on the back of the glass fiber filter membrane is removed first, and then the glass fiber filter membrane fragments on the surface of the silver selenide film are wiped off to obtain a flexible N-type nylon-based silver selenide thermoelectric film. Its power factor at 30°C is 3038.33μW/(mK ² ).

Example 5:

(1) Dissolve silver nitrate and selenium powder with a molar ratio of 2.3:1 in 7.5mL and 10mL of ethylenediamine respectively, stir for 30min, pour into a 25mL reaction kettle, and place the reaction kettle in a blast drying oven React at 180°C for 5 hours; the obtained product was alternately centrifuged and washed with deionized water and ethanol for 2 to 3 times, and then ultrasonically dispersed the washed silver selenide particles into 10 mL of ethylene glycol to obtain a uniform silver selenide dispersion; The concentration of silver selenide is 29mg/mL;

(2) Under the assisted condition of vacuum suction, the silver selenide dispersion liquid obtained in step (1) is evenly drip-coated on the glass fiber filter membrane of 20mm*5mm, and the drip coating amount of the silver selenide dispersion liquid is 1.2 mL/cm ² , after the liquid is drained, dry it in a vacuum oven at 60°C to obtain a silver selenide film adhered to the glass fiber filter membrane;

(3) Place the silver selenide thin film adhered on the glass fiber filter membrane that step (2) obtains between two nylon filter membranes, through spark plasma sintering (SPS) molding, sintering temperature is 200 ℃, sintering The time is 3 minutes, the pressure is 30MPa, and then the nylon filter membrane on the back of the glass fiber filter membrane is removed first, and then the glass fiber filter membrane fragments on the surface of the silver selenide film are wiped off to obtain a flexible N-type nylon-based silver selenide thermoelectric film. Its power factor at 30°C is 3862.3μW/(mK ² ).

Embodiment 6:

(1) Dissolve silver nitrate and selenium powder with a molar ratio of 2.3:1 in 7.5mL and 10mL of ethylenediamine respectively, stir for 30min, pour into a 25mL reaction kettle, and place the reaction kettle in a blast drying oven React at 180°C for 5 hours; the obtained product was alternately centrifuged and washed with deionized water and ethanol for 2 to 3 times, and then ultrasonically dispersed the washed silver selenide particles into 10 mL of ethylene glycol to obtain a uniform silver selenide dispersion. The concentration of silver selenide is 29mg/mL;

(2) Under the assisted condition of vacuum suction, the silver selenide dispersion liquid obtained in step (1) is evenly drip-coated on the glass fiber filter membrane of 20mm*5mm, and the drip coating amount of the silver selenide dispersion liquid is 1.2 mL/cm ² , after the liquid is drained, dry it in a vacuum oven at 60°C to obtain a silver selenide film adhered to the glass fiber filter membrane;

(3) Place the silver selenide thin film adhered on the glass fiber filter membrane that step (2) obtains between two nylon filter membranes, through spark plasma sintering (SPS) molding, sintering temperature is 200 ℃, sintering The time is 7 minutes, the pressure is 30MPa, and then the nylon filter membrane on the back of the glass fiber filter membrane is removed first, and then the glass fiber filter membrane fragments on the surface of the silver selenide film are wiped off to obtain a flexible N-type nylon-based silver selenide thermoelectric film. Its power factor at 30°C is 2722.1 μW/(mK ² ).

Claims (5)

1. a preparation method of flexible N-type nylon-based silver selenide thermoelectric thin film, is characterized in that, the method may further comprise the steps: (1) Dissolve silver nitrate and selenium powder with a molar ratio of (2.1-2.5): 1 in ethylenediamine respectively, pour it into the reaction kettle after stirring, and place the reaction kettle in a blast drying oven at 180°C for 5 hours , the obtained product was alternately centrifuged and washed with deionized water and ethanol for 2 to 3 times, and then ultrasonically dispersed the washed silver selenide particles into 10 mL of ethylene glycol to obtain a uniform silver selenide dispersion; The concentration is 25-35mg/mL; (2) Under the assisted condition of vacuum filtration, the silver selenide dispersion liquid obtained in step (1) is evenly drip-coated on the glass fiber filter membrane, and the drip coating amount of the silver selenide dispersion liquid is 1-2mL/cm ^2. After the liquid is drained, dry it in a vacuum oven at 60°C to obtain a silver selenide film adhered to the glass fiber filter membrane; (3) Place the silver selenide thin film adhered on the glass fiber filter membrane that step (2) obtains between two nylon filter membranes, and form through discharge plasma sintering, the sintering temperature is 100-200 ℃, the sintering time 1-9min, pressure 30-50MPa, then first remove the nylon filter membrane on the back of the glass fiber filter membrane, and then wipe off the glass fiber filter membrane fragments on the surface of the silver selenide film to obtain a flexible N-type nylon-based silver selenide thermoelectric film . 2. The preparation method of flexible N-type nylon-based silver selenide thermoelectric thin film according to claim 1, characterized in that, the molar ratio of silver nitrate and selenium powder in step (1) is 2.3:1. 3. The preparation method of flexible N-type nylon-based silver selenide thermoelectric film according to claim 1, characterized in that the concentration of silver selenide in step (1) is 28-32 mg/mL. 4. the preparation method of flexible N-type nylon-based silver selenide thermoelectric film according to claim 1 or 2, is characterized in that, in step ( ² ), the drop coating amount of silver selenide dispersion liquid is 1.2mL/cm . 5. the preparation method of flexible N-type nylon-based silver selenide thermoelectric thin film according to claim 1 or 2, is characterized in that, the sintering temperature of discharge plasma sintering process in step (3) is 130-200 ℃, sintering time 1-7min, pressure 30MPa.

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