A novel DES electrode, an energy harvesting device based on this electrode, and its applications

Abstract

The present invention relates to the field of triboelectric nanogenerators, and specifically relates to a novel DES electrode and an energy harvesting device based on the electrode and its applications. The energy harvesting device includes the DES ionic gel, the outside of the DES ionic gel is coated with a PDMS layer, a carbon tape extending out of the PDMS layer is connected to the DES ionic gel, and a batch of energy harvesting devices are installed on the tree branches to be used for constructing a smart tree for lighting and self-functional sensors. The smart tree can efficiently collect raindrop energy and breeze energy at the same time. The specially modulated DES ionic gel has the characteristics of environmental protection, flexibility, biodegradability, and self-healing. Compared with electronic conductors such as metal materials and carbon materials, it is easy to form an electric double layer to enhance the output performance of the TENG.

Description

Technical Field

[0001] The present invention relates to the field of friction nanogenerators, and in particular to a novel DES electrode and an energy collection device based on the electrode and applications thereof. Background Art

[0002] The development of sensor networks has put forward new demands for widely distributed mobile power sources. Although these power sources can be very small, the number required is as high as millions to billions. Long-term, real-time and accurate agricultural information sensing technology is the prerequisite for realizing smart agriculture and forestry. Traditional agricultural and forestry sensing relies on weather stations, manual sensors and fixed monitoring points. Due to human resource limitations and few sampling points, accurate perception cannot be achieved. It is often difficult to lay pipelines in the fields, the battery life is limited and the pollution risk is more prominent. Therefore, the construction of distributed green power provides a new idea for intelligent perception. The development of "green distributed energy, passive perception" is a major trend in the future of smart agriculture and forestry.

[0003] Rainfall is the most common natural phenomenon, and there is a huge amount of energy behind this phenomenon. Taking the annual rainfall of 2446mm in Yangjiang City as an example, assuming that the cloud layer is 1500m above the ground, it is estimated that the gravitational potential energy of raindrops in Yangjiang City is 2.681*10^17J, equivalent to 74.5 billion kWh, which is five times the total social electricity consumption of Yangjiang City in 2021, 14.899 billion kWh. In the process of raindrops falling, the gravitational potential energy of raindrops is converted into kinetic energy and electrostatic energy, but these energies, especially electrostatic energy, are rarely collected and used. In farms or remote mountainous areas, where rainfall is abundant, transportation infrastructure is imperfect, and power supply and maintenance are not coordinated, collecting raindrop energy and converting it into electrical energy will be a good solution to such power supply problems. Traditional wind power generation technology is mature, but its installation site requires an annual average wind speed of more than 6m / s. Although my country's 10m high land can develop wind energy reserves of up to 250 million kilowatts, the three to seven wind areas that can be used by traditional wind turbines in my country only account for 11% of the country's area, and the wind level in most other areas is below three, which means that most of the wind energy is not effectively utilized. How to effectively utilize the "highlight" of wind energy in the environment - low-speed wind energy is a difficult problem that needs to be solved urgently in the utilization of wind energy. The triboelectric nanogenerator (TENG) based on the friction electrification and electrostatic induction coupling effect can collect breeze energy, raindrop potential energy and electrostatic energy, and has great potential in collecting wind energy and raindrop energy. It has the advantages of being able to collect low-frequency mechanical energy in the environment, simple structure, light weight, low cost, and green environmental protection. On the other hand, for large-scale environmental monitoring, traditional batteries need to be replaced or charged regularly, which leads to maintenance difficulties and environmental problems.

[0004] Currently, the construction of triboelectric nanogenerators mainly uses solid materials (such as silver nanowires, carbon nanotubes, and carbon flakes) as working electrodes, which can effectively collect wind energy and raindrop energy when not deformed. However, when the device is deformed by external stress (including torsion, tension, and folding), due to the high Young's modulus of these solid materials, irreversible damage is easily caused, resulting in a shortened lifespan of the triboelectric nanogenerator.

[0005] In addition, the current TENG also has the following deficiencies:

[0006] 1) Triboelectric nanogenerators usually have a small power density. How to effectively promote charge transfer is the key to improving the output performance of triboelectric nanogenerators.

[0007] 2) Triboelectric nanogenerators have poor environmental adaptability. Metal electrodes are easily damaged due to breakage, deformation, oxidation, and corrosion in harsh environments.

[0008] 3) It is difficult to degrade the metal materials and polymer materials used in TENG as friction layers, which causes environmental pollution after being discarded.

[0009] 4) Most TENGs collect energy in a single form and can only collect wind energy or raindrop energy alone, which needs to be optimized. Summary of the Invention

[0010] Based on this, it is necessary to provide a novel DES electrode, an energy harvesting device based on this electrode, and its applications in view of the problems of the prior art.

[0011] To solve the problems of the prior art, the technical solution adopted by the present invention is as follows:

[0012] A novel DES electrode, the preparation of which includes the following steps:

[0013] S1. Mix choline chloride and acrylic acid in a molar ratio of 1:2, stir at 90 °C for 4 h to obtain a deep eutectic solvent (DES), and mix it with a 4M NaOH solution in a ratio of 1:1 to obtain solution A;

[0014] S2. Dissolve the initiator potassium persulfate, the crosslinking agent sodium sulfite, and the catalyst ammonium cerium nitrate solution to 20 g / L respectively. Add 1.5 g of 50-mesh algal powder, 10 ml of potassium persulfate solution, and 2 ml of ammonium cerium nitrate solution to a beaker and stir for 15 min;

[0015] S3. Add 3 ml of sodium nitrite solution and 30 ml of solution A to the solution of S2 in sequence and let it stand for 45 min;

[0016] S4. Add 0.05 g of N,N'-methylenebisacrylamide (MBA) to the solution of S3, and stir for 4 h at 50 °C. After cooling, the DES ion gel is obtained.

[0017] An energy harvesting device based on the above DES electrode, the energy harvesting device includes the above DES ion gel, a PDMS layer is coated on the outside of the DES ion gel, and a carbon tape extending out of the PDMS layer is connected to the DES ion gel.

[0018] The preparation method of the PDMS layer is to mix the polydimethylsiloxane colloid and the curing agent according to a mass ratio of 10:1 and stir evenly. After defoaming by ultrasonic wave for 30 min, it is cast on a mold and dried at 65 °C for 2 h.

[0019] The application of the energy harvesting device as lighting power supply. A plurality of the energy harvesting devices are distributed and installed on each tree branch to form a triboelectric power generation smart tree. An electrical appliance is arranged on the triboelectric power generation smart tree. One end of the carbon tape of all the energy harvesting devices is respectively connected to a rectifier in parallel to output electric energy to supply the electrical appliance.

[0020] The PDMS layer of each energy harvesting device serves as a triboelectric negative electrode to collect wind energy and raindrop energy.

[0021] When collecting raindrop energy, raindrops act as a triboelectric positive electrode and interact with the triboelectric negative electrode to generate electric energy.

[0022] When collecting gentle wind energy, tree leaves act as a triboelectric positive electrode and interact with the triboelectric negative electrode to generate electric energy.

[0023] The application of the energy harvesting device as lighting power supply, and the electrical appliance is an LED lamp.

[0024] Based on the application of the energy harvesting device as a sensor, the sensor is the energy harvesting device body. The sensor collects the voltage-time waveform curves generated when different materials come into contact with the energy harvesting device. The collected waveform curve data is trained and learned by a machine, so as to classify different characteristic waveform curves, and finally identify the contacted object according to the type of the waveform curve.

[0025] The beneficial effects of the present invention compared with the prior art are as follows:

[0026] First, the DES gel of the present invention is green and environmentally friendly, has great advantages compared with toxic ion gels, and adding algal powder can effectively improve the mechanical properties. It is not afraid of bending and oxidation and other harsh conditions, and greatly extends the life of the electrode.

[0027] Second, the present invention optimizes the structure of the TENG so that it can collect wind energy and raindrop energy simultaneously, which has great advantages compared with traditional tribogenerators;

[0028] Third, the present invention effectively enhances the output performance of the TENG by forming an electric double layer between the DES ionic gel and the carbon tape;

[0029] Fourth, the present invention effectively increases the energy collection density by installing a batch of electrodes on tree branches;

[0030] Fifth, the present invention enables the triboelectric nanogenerator to be used for environmental range monitoring by using the electrode itself as a sensor to analyze and learn the waveform of the environmental contact material. Description of the Drawings

[0031] Figure 1 is a schematic plan view of the energy collection device of the present invention;

[0032] Figure 2 is a voltage-time curve graph of different material contact electrodes detected by the present invention;

[0033] The reference numbers in the figure are: 1 - DES ionic gel; 2 - PDMS layer; 3 - carbon tape. Detailed Embodiments

[0034] To further understand the features, technical means, and specific purposes and functions achieved by the present invention, the present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0035] A novel DES electrode, the preparation of which includes the following steps:

[0036] S1, Mix choline chloride and acrylic acid in a molar ratio of 1:2, stir at 90 °C for 4 h to obtain a deep eutectic solvent (DES), and mix it with a 4 M NaOH solution in a ratio of 1:1 to obtain solution A;

[0037] S2, Dissolve the initiator (potassium persulfate), crosslinking agent (sodium sulfite), and catalyst (ammonium cerium nitrate) solutions to 20 g / L respectively. Add 1.5 g of 50-mesh algal powder, 10 ml of potassium persulfate solution, and 2 ml of ammonium cerium nitrate solution to a beaker and stir for 15 min;

[0038] S3, Add 3 ml of sodium nitrite solution and 30 ml of solution A to the solution of S2 in sequence and let it stand for 45 min;

[0039] S4, Add 0.05 g of methylene bisacrylamide (MBA) to the solution of S3, and stir at 50 °C for 4 h. After cooling, the DES ionic gel is obtained.

[0040] Ionic gels have the advantages of flexibility, biodegradability, self-healing, etc. More importantly, ionic gels have tunable ionic conductivity. Compared with electronic conductors such as metal materials and carbon materials, it is easy to form an electric double layer to enhance the output performance of TENG.

[0041] Referring to Figure 1 As shown, for the energy harvesting device based on the above-mentioned novel DES electrode, the energy harvesting device includes the described DES ionic gel, a PDMS layer is coated on the outside of the DES ionic gel, and a carbon tape extending out of the PDMS layer is connected to the DES ionic gel. The triboelectric nanogenerator constructed in this project mainly consists of two parts: an electrode layer and a triboelectric layer, and is externally connected to a wire to connect to an external circuit. Considering performance and environmental protection, a degradable DES ionic gel is prepared as the electrode material of the triboelectric nanogenerator, PDMS is used as the triboelectric negative electrode material, and water droplets and leaves are used as the triboelectric positive electrode materials.

[0042] For the preparation method of the described PDMS layer, polydimethylsiloxane colloid and curing agent are mixed at a mass ratio of 10:1 and stirred evenly, defoamed by ultrasonic wave for 30 min, cast on a mold and dried at 65 °C for 2 h.

[0043] During the process of plants in the environment being exposed to wind and rain, there is abundant environmental energy, but few scholars have collected this part of wind and rain energy. Triboelectric nanogenerators can effectively collect low-frequency energy in the environment, and leaves are also suitable materials for the triboelectric layer of triboelectric nanogenerators. Therefore, we apply the triboelectric nanogenerator to trees to collect breeze energy and raindrop energy. A number of the described energy harvesting devices are distributed and installed on each branch to form a triboelectric power generation smart tree. An electrical appliance is set on the triboelectric power generation smart tree, and the electrical appliance can be an LED lamp. One end of the carbon tape of all energy harvesting devices is respectively connected to a rectifier in parallel to output electric energy to supply the LED lamp;

[0044] When the wind blows, the leaves and the polydimethylsiloxane (PDMS) film can come into contact and separate regularly, thus generating an electric current in the external circuit. When it rains, due to the positively charged raindrops hitting the PDMS, the electrostatic energy and mechanical energy of the raindrops are converted into electric energy. The collected energy can be used for LED lighting and powering the following sensors.

[0045] Working principle of raindrop energy harvesting: The energy of raindrops includes kinetic energy converted from gravitational potential energy and electrostatic potential energy generated by friction with air. A triboelectric nanogenerator can effectively harvest the electrostatic energy of raindrops. Introducing an ionic conductor into the triboelectric nanogenerator will generate an electric double layer at the interface between the ionic gel and the carbon tape. The charge separation distance in the electric double layer is usually in the nanometer range, which leads to a high capacitance and improves the charge transfer and output performance of the ionic gel-based TENG. After friction with air, raindrops carry a positive charge. When the positively charged raindrops flow on the hydrophobic PDMS film, free ions will move to the interface between the ionic gel and PDMS to form an excess layer of ions in order to balance the static charge. This will cause interfacial polarization between the carbon tape and the ionic gel, resulting in the generation of the same number of ions and electrons with opposite charges at the interface and in the carbon tape. Electrons flow from the wire through the external load to the ground, and the flow of free electrons continues until the potential difference completely disappears. Once the raindrop slides out of the PDMS surface, a potential difference will be formed between the ionic gel and the ground, driving electrons to flow back to the ground from the ionic gel until it returns to the initial state.

[0046] Working principle of wind energy harvesting: When a leaf touches the PDMS surface, the electron affinity of PDMS is higher than that of the leaf. The contact will make the PDMS surface negatively charged, and at the same time make the leaf carry the same amount of positive charge.

[0047] Experimental data of raindrop energy harvesting:

[0048] At a rainwater flow rate of 2 ml / s, the open-circuit voltage and short-circuit current reach 34.1 V and 0.37 μA respectively. To evaluate the optimal matching impedance and maximum output power of the TENG, a series of different load resistors are used to test its output performance. The droplet impact on the TENG can directly light up 40 LED lights. At a load resistor of 3.5 MΩ, a maximum output power density of 73.67 mW / m2 is obtained.

[0049] Experimental data of gentle wind energy harvesting:

[0050] The TENG driven by wind energy can harvest the energy of a gentle wind of 2.5 m / s. Using mulberry leaves as the triboelectric positive electrode material, its open-circuit voltage is 4.2 V. As the wind speed increases from 2.5 m / s to 5.5 m / s, the short-circuit current shows a gradually increasing trend. To evaluate the optimal matching impedance and maximum output power of the TENG, a series of different load resistors are used to test its output performance. At a load resistor of 10 MΩ, a maximum output power density of 1.7 mW / m2 is obtained.

[0051] In addition to being able to collect raindrop energy and wind energy, the triboelectric nanogenerator-based intelligent energy tree can also be used as a self-powered sensor for intelligent identification. The application of the energy harvesting device based on the triboelectric nanogenerator as a sensor includes the above-mentioned triboelectric intelligent tree. The sensor is the energy harvesting device itself. The sensor collects the voltage-time waveform curves generated when different materials come into contact with the energy harvesting device. The collected waveform curve data is used for machine training and learning. Thus, different characteristic waveform curves can be classified. Finally, the contact object is identified according to the type of the waveform curve. In this way, it can be used as a self-powered sensor for "intelligent" identification of pests and birds approaching the tree.

[0052] When the triboelectric nanogenerator comes into contact with different materials, voltage-time curves with different characteristics can be generated. These data sets are preprocessed and used for machine learning to classify different characteristic waveform curves. When a bird flies over the triboelectric nanogenerator, a voltage-time curve with a high frequency and dense waveform will be generated. When a pest crawls over the triboelectric nanogenerator, a curve with a low frequency and a larger voltage peak compared to when a bird flies over will be generated. This can be used to trigger a bird repelling system or a pest warning after identifying flying birds and pests in farms and orchards, and timely take prevention and control measures against pest and bird damage. This will have great potential for application in intelligent farms. When an electron-rich finger or clothing repeatedly contacts and separates from the triboelectric nanogenerator, different time-voltage response curves will be generated. This can be used to achieve real-time monitoring of unmanned areas. When an intruder passes by, the real-time monitoring system can be awakened, the collected sound can be processed, and the safety of the scene can be judged. Its unique structure enhances its concealment in the natural environment, making it more promising in the field of unmanned monitoring. The triboelectric nanogenerator-based intelligent energy tree can also detect different weather conditions, such as wind and rain, which can be used for strong wind and heavy rain warnings. As Figure 2 Shown are the voltage-time curves generated by different contact materials.

[0053] Benefit calculation:

[0054] Our team installed TENG units on tree branches to construct a degradable ionic gel-based triboelectric nanogenerator intelligent energy tree for harvesting breeze energy and raindrop energy. It can not only be freely and flexibly arranged as a distributed power source in complex environments, but also act as a self-powered sensor - "intelligently" identifying by analyzing the different waveforms generated when different objects come into contact with the triboelectric nanogenerators on the intelligent energy tree. Taking the climate with an annual average rainfall of 2400 mm and an average annual wind speed of 3.24 m / s in cities across the country as an example, installing triboelectric nanogenerators in an orchard of one mu to construct a triboelectric nanogenerator energy tree, the expected annual power generation from raindrops is 134.45 kW⋅h, and the annual power generation from gentle breeze is 21.25 kW⋅h, with a total annual power generation of 155.7 kW⋅h, which is equivalent to reducing the use of 62.9 kg of standard coal and reducing the CO2 emissions by approximately 155.23 kg. As shown in the following table, the harvested energy can meet the lighting needs during the picking season of an orchard of one mu and the power consumption needs of environmental monitoring sensors.

[0055] Power consumption calculation for orchard sensors and lighting

[0056]

[0057] The above embodiments only represent one or several implementation manners of the present invention, and the description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. An energy harvesting device based on a DES electrode, characterized in that The energy harvesting device includes a DES ionic gel, the outside of which is coated with a PDMS layer, and a carbon tape extending out of the PDMS layer is connected to the DES ionic gel; Among them, the preparation of the DES ionic gel includes the following steps: S1, Mix choline chloride and acrylic acid in a molar ratio of 1:2, stir at 90 °C for 4 h to obtain a deep eutectic solvent (DES), and mix it with a 4M NaOH solution in a ratio of 1:1 to obtain solution A; S2, Dissolve the initiator potassium persulfate, the crosslinking agent sodium sulfite, and the catalyst ammonium cerium nitrate solution to 20 g / L respectively. Add 1.5 g of 50-mesh algal powder, 10 ml of potassium persulfate solution, and 2 ml of ammonium cerium nitrate solution to a beaker and stir for 15 min; S3, Add 3 ml of sodium nitrite solution and 30 ml of solution A to the solution in S2 in sequence and let it stand for 45 min; S4, Add 0.05 g of methylenebisacrylamide (MBA) to the solution in S3, and stir at 50 °C for 4 h. After cooling, the DES ionic gel is obtained.

2. The energy harvesting device based on a DES electrode according to claim 1, wherein The preparation method of the PDMS layer is as follows: Mix the polydimethylsiloxane colloid and the curing agent in a mass ratio of 10:1 and stir evenly. Remove bubbles by ultrasonic wave for 30 min, then cast it on a mold and dry it at 65 °C for 2 h.

3. Application of the energy harvesting device according to claim 1 for lighting power supply, characterized in that, Install a plurality of the energy harvesting devices described in claim 1 on each branch to form a triboelectric power generation smart tree. An electrical appliance is provided on the triboelectric power generation smart tree. One end of the carbon tape of all the energy harvesting devices is respectively connected to a rectifier in parallel to output electric energy to supply the electrical appliance; The PDMS layer of each energy harvesting device serves as a triboelectric negative electrode to collect wind energy and raindrop energy; When collecting raindrop energy, the raindrop acts as a triboelectric positive electrode and acts with the triboelectric negative electrode to generate electric energy; When collecting gentle wind energy, the leaf acts as a triboelectric positive electrode and acts with the triboelectric negative electrode to generate electric energy.

4. Use of the energy harvesting device according to claim 3 for lighting power supply, characterized in that, The electrical appliance is an LED lamp.

5. Use of the energy harvesting device according to claim 1 as a sensor, characterized in that, The sensor is the energy harvesting device body. The sensor collects the voltage-time waveform curve generated when different materials come into contact with the energy harvesting device. The collected waveform curve data is trained and learned by a machine, so that different characteristic waveform curves can be classified, and finally the contact object is identified according to the type of the waveform curve.

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