RGO-PEI/PVDF PYROELECTRIC THIN FILM AND ITS PREPARATION METHOD

Abstract

The present invention belongs to the technical field of energy conversion devices, which provides an rGO-PEI/PVDF pyroelectric thin film, and the method for preparing the film, as well as a self-energized bracelet produced based on such film, which utilizes the reduced graphite oxide after modified by polyethyleneimine (PEI) (rGO-PEI) as photothermal conversion material, and the silver-plated polarized polyvinylidene fluoride (PVDF) film as pyroelectric conversion material. The rGO-PEI photothermal material is fixed to the surface of the PVDF through a transparent film, and prepare the self-energized bracelet based on it. The obtained bracelet has an output power of up to 21.3 mW/m2, and does not require additional mechanical devices to control the temperature during operation, wherein, the thermoelectric conversion, rectification, storage and application are realized through temperature fluctuation produced by absorbing sunlight during doing outdoor sports, utilizing temperature difference of air flow, and sweeping gesture, etc.

Claims

1. An rGO-PEI/PVDF pyroelectric thin film, characterized in that consisting of an rGO-PEI photothermal material layer and a PVDF film, wherein, the rGO-PEI photothermal material layer is fixed and attached to the surface of the PVDF film through the transparent film; the said PVDF film is a flexible polarized PVDF film with double-side Ag film coating, wherein the mass percentage of β phase is higher than 90%; the surface density of the said rGO-PEI photothermal material layer is 1 mg/cm.sup.2; wherein, the rGO-PEI photothermal material contains a grafting rate of PEI of 22.3%.

2. The said rGO-PEI/PVDF pyroelectric thin film according to claim 1, characterized in that the light transmittance of the said transparent film is greater than 90%, which is made of polyethylene terephthalate with a coefficient of thermal expansion of 127×10.sup.−6K.sup.−1.

3. The preparation method of the said rGO-PEI/PVDF pyroelectric thin film according to claim 1, characterized in that consisting of following steps: S1. Take PEI as a modifier to complete chemical modification to GO, and thus obtain the rGO-PEI photothermal material after preparation; S2. Disperse the rGO-PEI photothermal material in the ethanol solution, and then form a layer of rGO-PEI photothermal material on the filter paper by means of suction filtration and dry it at room temperature, and thus obtain the rGO-PEI photothermal material layer; S3. Utilize a transparent film to transfer and fix the rGO-PEI photothermal material layer on the surface of the polarized PVDF film, and fold the edge of the transparent film and attach it to the edge of the other surface of the polarized PVDF film, and thus obtain the rGO-PEI/PVDF pyroelectric thin film.

4. The said method for preparing rGO-PEI/PVDF pyroelectric thin film according to claim 1, characterized in that: the specific operation of the said step S1 is to weight GO powder and disposed it in deionized water by ultrasonic, and then add KOH and PEI successively and stir them for 30 minutes to dissolve, and thus obtain a mixed solution, after that place the mixed solution in an oil bath at the temperature of 80° C. and stir for reaction for 10 hours, and then, centrifuge and wash the solution experienced reaction 3-4 times, and then complete freeze drying, and thus obtain the rGO-PEI photothermal material.

5. The said method for preparing rGO-PEI/PVDF pyroelectric thin film according to claim 1, characterized in that the mass ratio of the GO powder to the PEI is 1:30.

6. The said method for preparing rGO-PEI/PVDF pyroelectric thin film according to claim 1, characterized in that: the specific operation of the said step S2 is to suction and filter the ethanol solution of rGO-PEI through a filter paper with a pore size of 0.22 microns, and then control the surface density of the formed photothermal layer to 1 mg/cm2.

7. A self-energized bracelet produced based on a pyroelectric thin film, characterized in that consisting of the rGOPEI/PVDF pyroelectric thin film described in claim 1, a copper electrode, a rectifier bridge and a capacitor, wherein, the said copper electrode is connected to the surface of the PVDF film between the rGO-PEI photothermal material layer and the PVDF film, and extends from the surface of the PVDF film, and thus connects with the rectifier bridge and the capacitor successively.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0027] Based on the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings below, these and/or other aspects and advantages of the present invention will become clearer and easier to understand, wherein:

[0028] FIG. 1 is a schematic photo of the overall wearing of a self-energized bracelet based on the rGO-PEI/PVDF pyroelectric thin film prepared according to an embodiment of the present invention;

[0029] FIG. 2 is a schematic diagram of the layer structure composition of the rGO-PEI/PVDF pyroelectric thin film utilized by the self-energized bracelet based on the rGO-PEI/PVDF pyroelectric thin film prepared according to an embodiment of the present invention;

[0030] FIG. 3 is a photo showing the self-energized bracelet prepared according to an embodiment of the present invention to be used to collect heat generated by outdoor sunlight and then supply power to the human health monitor immediately;

[0031] FIG. 4 is a time-current curve graph obtained in the case that the self-energized bracelet prepared according to an embodiment of the present invention collects heat existed in the air at night;

[0032] FIG. 5 is a time-current curve graph obtained in the case that the self-energized bracelet prepared according to an embodiment of the present invention is used to collect energy generated through evaporation of human sweat.

DESCRIPTION OF THE INVENTION

[0033] For the purpose of helping those skilled in the art to understand the present invention better, the text below will describe the present invention in detail in conjunction with the accompanying drawings and specific embodiments.

Embodiment 1

[0034] A preparation method of a self-energized bracelet based on rGO-PEI/PVDF pyroelectric thin film, which consists of following steps:

[0035] 1) Take PEI as a modifier to complete chemical modification to GO, and thus obtain the rGO-PEI photothermal material after preparation, wherein, the specific operation is: weigh 0.11 g of GO powder and disposed it in 100 ml of deionized water by ultrasonic, and then add 0.2 g of KOH and 3 g of PEI successively and stir them for 30 minutes to dissolve, and then place the mixed solution in an oil bath at the temperature of 80° C. and stir for reaction for 10 hours, finally, centrifuge and wash the solution experienced reaction 3-4 times, as well as complete freeze drying;

[0036] 2) Disperse rGO-PEI in the ethanol solution, and then form a layer of rGO-PEI layer on the filter paper by means of suction filtration and dry it at room temperature, and thus obtain the rGO-PEI photothermal layer; wherein, the specific operation is: Disperse the rGO-PEI evenly in 6m1 of ethanol solution, and then drop them on the surface of filter paper evenly as well as guarantee that the surface density of the material is 1 mg/cm2, after that, complete suction filtration, and dry them at room temperature for 2 hours;

[0037] 3) Separately paste the two copper electrodes on one surface of the polarized PVDF film;

[0038] 4) Then, transfer and fix the rGO-PEI photothermal layer on the surface of the polarized PVDF film where there is a copper electrode is fixed by utilizing the transparent film (The transparent film utilized in the present embodiment is PET transparent tape), after that, connect it to the rectifier bridge and the capacitor at the extension end of the copper electrode, meanwhile, cut it into corresponding bracelet, and thus, obtain the self-energized bracelet based on rGO-PEI/PVDF pyroelectric thin film; it should be noted that the extra part of the transparent tape needs to be reserved and attached to the reverse side of the PVDF film, and thus guarantees the photothermal layer to contact with the pyroelectric layer closely.

[0039] The overall structure and the layer structure of the obtained self-energizing bracelet based on rGO-PEI/PVDF pyroelectric thin film are shown in FIG. 1 and FIG. 2 respectively.

Embodiment 2

[0040] In the event that wear the self-energized bracelet based on the rGO-PEI/PVDF pyroelectric thin film obtained in the embodiment 1 during doing outdoor exercise, the heat generated by the sunlight can be converted into pyroelectricity by virtue of the swing of the wrist when the human body walks, and the pyroelectricity will be stored in capacitor after being output through electrodes, and rectified by rectifier bridge, and thus can be used to provide power for the human health monitor immediately. The experimental result shows that: such self-energized bracelet can charge the human health monitor about 10% of electric energy, if walks for 1 hour under the sunshine, and its application is as shown in FIG. 3.

Embodiment 3

[0041] In the event that wear the self-energized bracelet based on the rGO-PEI/PVDF pyroelectric thin film obtained in the embodiment 1 during walking at night, the movement of the wrist will give rise to the temperature fluctuation of the airflow, and thus generate pyroelectricity, which will be stored in capacitor after being output through electrodes, and rectified by rectifier bridge, and thus can be used to collect energy existed in air at night, wherein, the correlation curve between the walking time of people and the current obtained is as shown in FIG. 4.

Embodiment 4

[0042] To collect the energy generated through evaporation of human sweat: wear the self-energized bracelet based on the rGO-PEI/PVDF pyroelectric thin film obtained in the embodiment 1 on the wrist of a person who did exercise and sweated, and the self-energized bracelet can generates electricity by means of the temperature variation occurred during the liquid evaporation process (simulating the evaporation of human sweat), wherein, the output current reaches in the range of around 20 nA, and the correlation curve between the time and the current obtained in the process of collecting the energy generated through evaporation of human sweat is as shown in FIG. 5.

[0043] In conclusion, the self-energized bracelet based on the rGO-PEI/PVDF pyroelectric thin film of the present invention can collect the optothermal energy, the heat existed in the air at night, and the energy generated through evaporation of human sweat during doing outdoor exercise by people, which can be used to provide instant power supply to electronic devices (such as detectors for human health).

[0044] The embodiments of the present invention have been described above, and such description is exemplary, rather than exhaustive, and is not limited to the disclosed embodiments. In addition, various modifications and variations without departing from the scope and spirit of the described embodiments are obvious to those of ordinary skill in the art. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.