Humidity-enhanced TENG as well as preparation method and application thereof

Abstract

According to the humidity-enhanced TENG and the preparation method and application thereof provided by the invention, natural polysaccharide is modified to obtain a derivative film with high dielectric constant and moisture absorption rate as a positive electrode friction layer, so that the output performance of the TENG in a high-humidity environment is remarkably improved, and the humidity-enhanced TENG is suitable for the fields of human movement, respiration monitoring and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of tribo-nanoelectric power generation, and in particular to a humidity-enhanced TENG, a preparation method thereof, and applications thereof. Background Art

[0002] Triboelectric nanogenerators (TENGs) can convert mechanical energy from various sources in nature and daily life into usable electrical energy by utilizing the coupling effects of contact electrification and electrostatic induction. They have been widely used in energy harvesting systems, wearable electronics, health and environmental monitoring systems, etc. However, a major problem faced by most TENGs is their significant sensitivity to humidity. Under high relative humidity conditions, atmospheric moisture adsorbed on the surface of the TENG friction layer accelerates the transmission and dissipation of triboelectric charges, thereby greatly reducing the output performance and stability of the TENG and limiting its practical applicability. Humidity is ubiquitous in the environment where TENGs are used. Therefore, improving the output performance and working stability of TENGs under high humidity conditions remains an urgent problem to be solved.

[0003] Encapsulation and hydrophobic modification are common methods to improve the moisture resistance of TENG, but these methods are cumbersome and complex, and cannot completely reverse the trend of TENG performance decreasing with increasing humidity. Therefore, from the perspective of material design, it is an urgent challenge to fundamentally improve the moisture resistance of the friction interface and develop a moisture-resistant triboelectric nanogenerator with higher output performance under high humidity conditions to improve its environmental adaptability. Using hygroscopic biomaterials as the friction layer, a large amount of free water in the air can be converted into bound water, and the bound water participates in the contact separation process together with the friction layer. Since water molecules have a higher positive charge, the polarity difference between the two friction layers increases, thereby improving the output performance of TENG under humidity.

[0004] In view of this, the inventors specially designed a humidity-enhanced TENG, its preparation method and application, and this case was thus generated. Summary of the invention

[0005] In order to improve the output performance of TENG under high humidity and realize the application of TENG in respiratory monitoring and motion monitoring, one of the purposes of the present invention is to provide a humidity-enhanced TENG. The triboelectric performance of natural polysaccharides as positive electrode friction layers under high humidity is improved by chemical modification of natural polysaccharides.

[0006] In order to achieve the above object, the present invention provides a humidity-enhanced TENG, wherein the TENG uses a natural polysaccharide derivative film as a positive electrode friction layer.

[0007] Preferably, the dielectric constant of the natural polysaccharide derivative film is 30.7, and the moisture absorption rate at 90% humidity is 0.42 g / g.

[0008] Preferably, the natural polysaccharide derivative in the natural polysaccharide derivative film is obtained by modifying natural polysaccharides, and the molecular structure of the natural polysaccharide derivative includes but is not limited to groups such as aldehyde, amino, and hydroxyl.

[0009] Preferably, the natural polysaccharides used to prepare the natural polysaccharide derivative film include but are not limited to sodium alginate, cellulose, hyaluronic acid, starch and the like.

[0010] The second object of the present invention is to provide a method for preparing a humidity enhanced TENG, comprising the following steps: Step 1: Take 5 g of sodium alginate (SA) and add it to 25 g of ethanol solution, stir evenly to obtain SA suspension; take 2.2 g of sodium periodate and add it to 25 g of pure water, stir until dissolved to obtain sodium periodate solution; add the above sodium periodate solution to the above SA solution, stir in the dark at room temperature for 6 h; after the reaction is completed, add 2.5 g of ethylene glycol to the beaker, stir for 30 min, terminate the reaction, transfer the above solution after the termination of the reaction to a dialysis bag with a molecular weight cutoff of 3500, dialyze in pure water for 3 days, and freeze-dry the solution after the dialysis to obtain oxidized sodium alginate (OSA).

[0011] Step 2: Take 5 g of OSA and add it to 150 ml of N,N-dimethylformamide solution, use an ultrasonic probe to disperse it to obtain an OSA suspension, add 9.7 g of N,N'-diisopropylcarbodiimide to the OSA suspension, stir for 1 hour to activate the carboxyl group, then add 7-18 g of amino compound to the above solution, stir and react at room temperature for 12 hours, after the reaction, use fast filter paper to filter the solution, and rinse with DMF and ethanol solution for 3 times respectively, retain the solid powder, and vacuum dry it at 30-60°C for 24 hours to obtain a sodium alginate derivative (OSAN).

[0012] Step 3: Take 1 g of OSAN powder and add it to 9 g of pure water, stir evenly to obtain an OSAN solution. The solution is placed in a polytetrafluoroethylene mold and dried at room temperature for 12 h to form an OSAN film.

[0013] Step 4: Connect the above OSAN film as the positive friction layer to the electrode, and assemble it with the negative friction layer and the electrode into a humidity-enhanced TENG.

[0014] Preferably, the amino compound in step 2 includes but is not limited to diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and the like.

[0015] Preferably, the negative electrode friction layer in step 4 includes but is not limited to polytetrafluoroethylene, nylon, etc.

[0016] The third object of the present invention is to provide an application of a humidity-enhanced TENG for use in the field of human motion monitoring or human respiration monitoring.

[0017] The beneficial effects of the present invention are as follows: The present invention chemically modifies natural polysaccharides to prepare a natural polysaccharide derivative film with a dielectric constant of 30.7 and a moisture absorption rate of 0.42 g / g at 95% humidity. It is used as a positive friction material and assembled into a TENG with electrode and negative friction materials, achieving the effect of enhancing output performance with increasing ambient humidity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0019] in: Figure 1 It is the NMR spectra of the samples of Example 1 and Comparative Example 1 of the present invention.

[0020] Figure 2 Graphs showing dielectric constants of films according to Example 1 of the present invention and Comparative Example 1.

[0021] Figure 3 It is a graph of the moisture absorption performance of the film of Example 1 of the present invention and Comparative Example 1.

[0022] Figure 4 It is a data diagram of the open circuit voltage of the TENG of Example 1 of the present invention and Comparative Example 1 under a humidity environment of 55%.

[0023] Figure 5 This is a graph showing the open circuit voltage data of the humidity-enhanced TENG under different humidity conditions in Example 1 of the present invention.

[0024] Figure 6 This is a data graph of the humidity-enhanced TENG monitoring human motion in Example 1 of the present invention.

[0025] Figure 7 This is a data chart of the humidity-enhanced TENG monitoring human breathing in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Example

[0027] Step 1: Take 5 g of sodium alginate (SA) and add it to 25 g of ethanol solution, stir evenly to obtain SA suspension. Take 2.2 g of sodium periodate and add it to 25 g of pure water, stir until dissolved to obtain sodium periodate solution. Add the above sodium periodate solution to the above SA solution and stir for 6 h at room temperature in the dark. After the reaction is completed, add 2.5 g of ethylene glycol to the beaker and stir for 30 minutes to terminate the reaction. Transfer the above solution after the termination of the reaction to a dialysis bag with a molecular weight cutoff of 3500 and dialyze in pure water for 3 days. After the dialysis is completed, freeze-dry the solution to obtain oxidized sodium alginate (OSA).

[0028] Step 2: Take 5 g of OSA and add it to 150 ml of N,N-dimethylformamide solution, and disperse it using an ultrasonic probe to obtain an OSA suspension. Add 9.7 g of N,N'-diisopropylcarbodiimide to the OSA suspension and stir for 1 h to activate the carboxyl group. Then add 7-18 g of the amino compound to the above solution and stir the reaction at room temperature for 12 h. After the reaction, filter the solution with a quick filter paper and rinse it with DMF (N,N-dimethylformamide solution) and ethanol solution three times respectively. Keep the solid powder and vacuum dry it at 30-60°C for 24 h to obtain a sodium alginate derivative (OSAN).

[0029] Step 3: Take 1 g of OSAN powder and add it to 9 g of pure water, stir evenly to obtain an OSAN solution. The solution is placed in a polytetrafluoroethylene mold and dried at room temperature for 12 h to form an OSAN film.

[0030] Step 4: Connect the above OSAN film as the positive friction layer to the electrode, and assemble it with the negative friction layer and the electrode into a humidity-enhanced TENG.

[0031] Comparative Example 1: Step 1: Take 1 g of SA powder and add it to 9 g of pure water, stir evenly to obtain SA solution. Place the solution in a polytetrafluoroethylene mold and dry it at room temperature for 12 h to form a SA film.

[0032] Step 2: Connect the SA membrane as the positive friction layer to the electrode, and assemble it with the negative friction layer and the electrode into a TENG.

[0033] SA in Comparative Example 1 and OSA and OSAN prepared in Example 1 were dissolved in deuterated water and tested using a 600 MHz Bruker NMR spectrometer. Figure 1As shown in the figure, compared with SA, OSA has new peaks at 5.44 ppm and 5.68 ppm, corresponding to H on the aldehyde group, proving that OSA was successfully prepared. The peaks of OSAN at 3.50 ppm, 2.81 ppm and 2.56 ppm correspond to CH on the amino chain, and the peak at 1.17 ppm corresponds to NH in the amino chain, proving that OSAN was successfully prepared.

[0034] The dielectric constants of the SA film prepared in Comparative Example 1 and the OSA film and OSAN film prepared in Example 1 were measured using a precision LCR meter (Tonghui TH2840B). Figure 2 As shown in the figure, at 1000 Hz, the dielectric constants of SA film, OSA film and OSAN film are 5.3, 28.1 and 30.7, respectively. The results show that chemical modification significantly improves the dielectric constant of sodium alginate derivative film.

[0035] The SA film prepared in Comparative Example 1 and the OSA film and OSAN film prepared in Example 1 were placed in a constant temperature and humidity chamber, the humidity was controlled at 90%, and the temperature was controlled at 25°C, and the moisture absorption rate of the samples was tested and calculated. Figure 3 As shown in the figure, at 90% relative humidity, the saturated moisture absorption rates of SA membrane, OSA membrane and OSAN membrane were 0.18 g / g, 0.20 g / g and 0.42 g / g, respectively. The results showed that chemical modification significantly improved the moisture absorption properties of sodium alginate derivative membranes.

[0036] The contact separation and sliding process of TENG was driven by a digital linear motor, and the triboelectric properties of TENG prepared in Comparative Example 1 and humidity-enhanced TENG prepared in Example 1 were measured using a programmable electrometer (Keithley Model 6514) and a digital multimeter (Keithley DMM-6500), respectively. Figure 4 As shown, the output voltages of the TENG prepared in Comparative Example 1 and the humidity-enhanced TENG prepared in Example 1 are 2.2 mV and 19.9 mV, respectively. The results show that the chemical modification significantly improves the triboelectric properties of TENG.

[0037] The triboelectric properties of the humidity-enhanced TENG prepared in Example 1 at different humidity levels were characterized. Figure 5 As shown in the figure, with the increase of humidity, the output voltage gradually increases. The results show that the TENG prepared by the present invention has excellent triboelectric properties under high humidity.

[0038] The positive friction layer of the humidity-enhanced TENG prepared in Example 1 was attached to the sole of the experimenter's foot, and the negative friction layer was attached to the experimenter's insole, and the experimenter's walking process was measured and monitored. Figure 6As shown in the figure, the states of normal walking, fast walking, and running can be clearly distinguished according to the frequency and peak characteristics of the open circuit voltage signal. The difference in the time and magnitude of the applied pressure leads to the maximum output during fast walking and a relatively small output during slow walking. The results show that the humidity-enhanced TENG prepared by the present invention can monitor the human body's motion state in real time.

[0039] The humidity-enhanced TENG prepared in Example 1 was placed under the nose of the subject to measure and monitor the subject's breathing state. Figure 7 As shown in the figure, different breathing states produce different electrical output characteristics. When a person is in a calm or relaxed state, the breathing rate is slow, and only 4 output voltage characteristic peaks appear within 10 s. The peak group width is 0.25 s, and the maximum output voltage peak is 0.09 V. Deep breathing has the highest breathing intensity, so the corresponding output voltage characteristic peak is 0.23 V. When a person is in a state of rapid breathing, the breathing frequency is short and rapid, and 6 output voltage characteristic peaks appear within 10 s. The results show that the humidity-enhanced TENG prepared by the present invention can monitor the human respiratory state in real time.

[0040] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A humidity-enhanced TENG, characterized in that: The TENG uses a natural polysaccharide derivative film as the positive electrode friction layer.

2. A humidity-enhanced TENG according to claim 1, characterized in that: The dielectric constant of the natural polysaccharide derivative film is 30.7, and the moisture absorption rate at 90% humidity is 0.42 g / g.

3. The humidity-enhanced TENG according to claim 1, characterized in that: The natural polysaccharide derivative in the natural polysaccharide derivative film is obtained by modifying natural polysaccharides, and its molecular structure includes but is not limited to groups such as aldehyde, amino, and hydroxyl.

4. The humidity-enhanced TENG according to claim 1, characterized in that: The natural polysaccharides used to prepare the natural polysaccharide derivative film include but are not limited to sodium alginate, cellulose, hyaluronic acid, starch, etc.

5. A method for preparing the humidity-enhanced TENG according to claim 1, characterized in that: The steps include: Step 1, take 5 g of sodium alginate and add it to 25 g of ethanol solution, stir evenly to obtain SA suspension, take 2.2 g of sodium periodate and add it to 25 g of pure water, stir until dissolved to obtain sodium periodate solution, add the above sodium periodate solution to the above SA suspension, stir in the dark at room temperature for 6 h, add 2.5 g of ethylene glycol to the beaker after the reaction is completed, stir for 30 min to terminate the reaction, transfer the above solution after the termination of the reaction to a dialysis bag with a molecular weight cutoff of 3500, dialyze in pure water for 3 days, and freeze-dry the solution after the dialysis to obtain oxidized sodium alginate; Step 2: Take 5 g of oxidized sodium alginate and add it to 150 ml of N,N-dimethylformamide solution, use an ultrasonic probe to disperse it to obtain an OSA suspension, add 9.7 g of N,N'-diisopropylcarbodiimide to the OSA suspension, stir for 1 hour to activate the carboxyl group, then add 7-18 g of the amino compound to the above solution, stir and react at room temperature for 12 hours, after the reaction is completed, use a fast filter paper to filter the solution, and rinse it with DMF and ethanol solution for 3 times respectively, retain the solid powder, and vacuum dry it at 30-60°C for 24 hours to obtain a sodium alginate derivative; Step 3: Take 1 g of sodium alginate derivative powder and add it to 9 g of pure water, stir evenly to obtain an OSAN solution, place the solution in a polytetrafluoroethylene mold, and dry it at room temperature for 12 h to form an OSAN film; Step 4: Connect the above OSAN film as the positive friction layer to the electrode, and assemble it with the negative friction layer and the electrode into a humidity-enhanced TENG.

6. The preparation method according to claim 5, characterized in that: The amino compound in step 2 includes but is not limited to diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and the like.

7. The preparation method according to claim 5, characterized in that: The negative electrode friction layer in step 4 includes but is not limited to polytetrafluoroethylene, nylon, etc.

8. An application of the humidity-enhanced TENG as claimed in claim 1, characterized in that: Used for human motion monitoring or human breathing monitoring.

Images