A triboelectric nanogenerator connected to an electron cloud potential well to increase output current, and its preparation method and application

Abstract

This invention relates to a triboelectric nanogenerator (TENG) that connects electron cloud potential wells to achieve high output current. We embedded reduced graphene oxide (rGO), a conductive network capable of connecting electron cloud potential wells in multiple dielectric polymer segments, into two dielectric layers with significantly different electronegativities: ethyl cellulose (EC) and polydimethylsiloxane (PDMS). Results show that during TENG operation, more charge can be transferred from one triboelectric material to the other. The TENG based on this model exhibited a record-breaking high output current of 3000 μA in contact-separation mode. Furthermore, our TENG exhibited excellent durability in high-humidity environments, a significant challenge for conventional TENGs. This invention provides a novel and promising strategy for fabricating TENGs with ultrahigh output current and water resistance, which is crucial for their further development and practical applications.

Description

Technical Field

[0001] The invention relates to a friction nanogenerator connected to an electron cloud potential well to increase output current, and belongs to the field of energy collection. Background Art

[0002] Triboelectric nanogenerators (TENGs), based on a combination of triboelectric charging and electrostatic induction, can convert irregular, low-frequency, and ubiquitous mechanical energy into electrical energy. To date, TENGs have demonstrated promising applications in micro- and nanoscale power generation, self-powered sensing, and blue energy harvesting. Improving output performance and operational stability are key to TENG development. Numerous strategies have been developed to enhance the triboelectric performance of TENGs, including surface microstructuring, molecular design, and the incorporation of high-dielectric or high-electrode cathode / cathode materials. These strategies have resulted in increases in output voltage by several orders of magnitude, reaching the kV level. However, improvements in TENG output current remain limited due to limited charge transfer between the triboelectric layers. Several attempts have been made to improve charge transfer efficiency and thus output current. Avoiding vacuum breakdown and reducing the impedance of the triboelectric circuit are two typical approaches. However, these approaches impose demanding application conditions and complex device structures.

[0003] In the past year, we developed a new strategy to improve the charge transfer efficiency of TENG by matching the density of states between friction layers. As a result, we achieved a charge transfer efficiency of 1333 mA m -2 However, further improving the output using this strategy is challenging due to the small electronegativity difference of the friction layer. Therefore, developing new strategies to achieve higher output current remains crucial.

[0004] On the other hand, moisture resistance or waterproofing is another requirement for the practical application of TENGs in complex environments. In high humidity or rainy environments, the performance of traditional TENGs usually drops significantly due to the leakage of charges from the friction layer into the air. People have been working hard to improve the moisture resistance and waterproofing of materials. For example, the surface of the friction layer can be made hydrophobic through material selection or surface engineering to improve the stability of TENGs when the humidity is below 80-85%. However, in ultra-high humidity environments, the performance of TENGs usually still drops significantly. Therefore, designing and manufacturing high-performance TENGs that can work stably in ultra-high humidity and rainy environments remains a huge challenge. Summary of the Invention

[0005] The technical problem solved by the present invention is: a new strategy is proposed to improve the output current and moisture resistance of TENGs by connecting the electron cloud potential wells of the polymer segments in the triboelectric layer. The conductive network of reduced graphene oxide (rGO) is embedded in the triboelectric layer of ethyl cellulose (EC) and polydimethylsiloxane (PDMS), two materials with a large difference in electronegativity. The TENG obtained by connecting the electron clouds, called EL-TENG, shows a high output current due to the involvement of more electron cloud wells in the contact energization process. The prepared EL-TENG has a high open circuit voltage (V OC ) and a high short-circuit current of 3000 μA (I SC Due to the novel working mechanism, our EL-TENG can operate stably in high-humidity and rainy environments, which is a major challenge for conventional EL-TENGs. The advantages of EL-TENG will greatly promote its practical applications in energy harvesting and self-powered sensing.

[0006] In order to solve the above technical problems, the present invention proposes a technical solution: a method for preparing a triboelectric nanogenerator connected to an electron cloud potential well to achieve high output current, comprising the following steps:

[0007] (1) Reduced graphene oxide (rGO) was uniformly dispersed in an ethyl cellulose (EC) solution to prepare an EC / rGEC / rGO suspension with a mass fraction of 0.5-0.9 wt%. The prepared suspension was poured into a polytetrafluoroethylene (PTFE) mold and then annealed in a vacuum oven. The obtained EC / rGO composite film was peeled off and used as the positive triboelectric material of TENG.

[0008] (2) Dispersing rGO uniformly in a polydimethylsiloxane (PDMS) precursor to prepare a PDMS / rGO suspension with a mass fraction of 0.4-1 wt %. Pour the prepared suspension into a culture dish and dry it to obtain a PDMS / rGO composite film as the triboelectric material of the TENG.

[0009] (3) Cutting the obtained EC / rGO and PDMS / rGO membranes into appropriate sizes;

[0010] (4) PDMS / rGO and EC / rGO films cut into appropriate sizes were used as the triboelectric layers in EL-TENG. The two triboelectric layers were glued onto two copper foils to assemble a triboelectric nanogenerator EL-TENG that works in contact-separation mode and connects electron cloud potential wells to achieve high output current.

[0011] Preferably, the method comprises the following steps: dissolving EC in ethanol at 60°C to obtain a 10 wt% solution, mixing 5 mL of a 10 wt% 3-glycidoxypropyltrimethoxysilane solution with 50 mL of the EC solution; uniformly dispersing reduced graphene oxide in the EC solution to prepare EC / rGO suspensions with mass fractions of 0.5, 0.7, and 0.9 wt%, respectively; pouring the prepared suspensions into a polytetrafluoroethylene mold, and then annealing in a vacuum oven at 60°C for 12 h; peeling off the obtained EC / rGO composite film to serve as the positive triboelectric material of the TENG; and adjusting the thickness of different EC / rGO films to 0.1 mm-1 mm by adjusting the depth of the groove inside the mold.

[0012] The polydimethylsiloxane (PDMS) precursor and curing agent were mixed in a mass ratio of 10:1. rGO was evenly dispersed in the PDMS precursor to prepare PDMS / rGO suspensions with mass fractions of 0.4, 0.6, 0.8, and 1 wt %, respectively. The prepared suspensions were poured into a Petri dish and dried at 60°C for 12 h to obtain PDMS / rGO composite membranes. The thickness of different PDMS / rGO membranes was adjusted by adjusting the depth of the internal groove of the mold to 0.1 mm-1 mm. The obtained EC / rGO and PDMS / rGO membranes were cut into appropriate sizes of 3 × 3 cm. 2 ;

[0013] 3 × 3 cm 2 The PDMS / rGO and EC / rGO films of different sizes were then used as the triboelectric layers in the EL-TENG, and the two triboelectric layers were glued onto two pieces of copper foil to assemble the EL-TENG working in the contact-separation mode.

[0014] Preferably, ethyl cellulose (EC) has a viscosity of 3-7 mPa·s. Polydimethylsiloxane (PDMS) is available from Sylgard 184.

[0015] Preferably, reduced graphene oxide rGO, with a specific surface area = 66 m 2 , conductivity = 19 S cm -1 .

[0016] Preferably, when the proportion of rGO doped in the PDMS solution is 1 wt%, the thickness of the EC / rGO membrane is 0.6 mm, the thickness of the PDMS / rGO membrane is 0.6 mm, and the proportion of rGO doped in EC is 0.9 wt%, the initial distance between the friction layers is 6 mm, the operating frequency is 5 Hz, and the output voltage of the prepared friction nanogenerator is 2500 V and the output current is 3000 μA.

[0017] In order to solve the above technical problems, another technical solution proposed by the present invention is: a high-performance rainproof triboelectric nanogenerator prepared by any method.

[0018] In order to solve the above technical problems, another technical solution proposed by the present invention is: the application of the high-performance rainproof triboelectric nanogenerator can also perform well in high humidity environments and in the rain.

[0019] Preferably, it is applied to efficient energy harvesting and self-powered motion sensing in rain.

[0020] Preferably, it is applied in the fields of personal health monitoring, patient rehabilitation, exercise monitoring and human motion tracking.

[0021] Beneficial effects of the present invention:

[0022] This paper proposes a new method to improve the output current and moisture resistance of TENGs by connecting the electron cloud potential wells of the polymer segments in the triboelectric layer.

[0023] Here, we fabricated a triboelectric TENG by embedding a conductive network of reduced graphene oxide (rGO) into triboelectric layers of ethyl cellulose (EC) and polydimethylsiloxane (PDMS), two materials with significantly different electronegativity. The resulting TENG, termed EL-TENG, exhibits high output current due to the involvement of more electron cloud traps during contact energization. The fabricated EL-TENG exhibits a high open-circuit voltage (V) of up to 2500 V. OC ) and a high short-circuit current of 3000 μA (I SC ).

[0024] When the ratio of rGO doped in PDMS solution was 1 wt% and the ratio of rGO doped in EC was 0.9 wt%, the initial distance between the friction layers was 6 mm, the operating frequency was 5 Hz, the thickness of the EC / rGO membrane was 0.6 mm, and the thickness of the PDMS / rGO membrane was 0.6 mm, the best electrical performance (output voltage of 2500 V, output current of 3000 μA) was obtained.

[0025] Due to the novel working mechanism, our EL-TENG can operate stably in high-humidity and rainy environments, which is a major challenge for conventional EL-TENGs. The advantages of EL-TENG will greatly promote its practical applications in energy harvesting and self-powered sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1Design and output performance of the EL-TENG. (a) Schematic diagram of the device structure of a conventional dielectric TENG. (b) ECPW model of a conventional dielectric TENG based on EC and PDMS. (c) Schematic diagram of the device structure of the EL-TENG of the present invention. (d) Schematic diagram of the electron cloud potential well connection between the EC layer and the PDMS layer in the EL-TENG via the conductive network of reduced graphene oxide (rGO) sheets. (e) Simulated electron density at the PDMS / rGO and EC / rGO interfaces. (fh) Output (f) voltage, (g) current, and (h) charge of TENGs based on EC-PDMS and EC / rGO-PDMS / rGO (size = 3 × 3 cm²). (i) Output voltage and current of EL-TENGs based on EC / rGO-PDMS / rGO with different thicknesses. (j) Comparison of the current density of the EL-TENG of the present invention with that of a reported TENG operating in contact-separation mode.

[0027] Figure 2 EL-TENG performance optimization. (a) Resistance of EC / rGO and PDMS / rGO films with different rGO contents. (bc) Output (b) voltage and (c) current of EL-TENGs based on EC / rGO and PDMS / rGO with different rGO loadings. (df) EL-TENG performance at different (d) initial separation distances and (e, f) operating frequencies. (g) Output voltage stability of the EL-TENG over 5000 cycles.

[0028] Figure 3 Performance of the EL-TENG in high humidity and rainy environments. (ab) Peak voltage and current of (a) the dielectric material (PDMS-EC)-based TENG and (b) the EL-TENG when the relative humidity changes from 20% to 100%. (c) Water contact angle of EC, EC / rGO, PDMS, and PDMS / rGO films. (d) Schematic diagram of charge leakage in the dielectric TENG and (e) schematic diagram of charge leakage suppression in the EL-TENG. (fg) Output (f) voltage and (g) current of the EL-TENG in rainy environments.

[0029] Figure 4Demonstration of the EL-TENG as an energy supplier. (a, b) Output voltage and current of (a) the EL-TENG and (b) the dielectric TENG (PDMS-EC) under different external loads. (c) Power output of the EL-TENG and dielectric TENG under different external loads. (d) Circuit diagram of an EL-TENG equipped with an energy storage unit, used to power a thermohygrometer. (e) Voltage curves of 100, 220, 470 μF, and 1 mF capacitors charged by the EL-TENG. (f) Voltage-time curve of a thermohygrometer powered by the EL-TENG. Inset: Photograph of the power management system. (g) Circuit diagram and (h) photograph (inset) of 2688 series-connected LEDs powered by the EL-TENG. (i) Comparison with the number of LEDs illuminated by TENGs in the contact-separation mode (normalized to the TENG surface area).

[0030] Figure 5 Demonstration of the EL-TENG as a self-powered wearable sensor. (a) Schematic diagram of the self-powered sensor mounted on a human body. (b) Monitoring the EL-TENG's motion state by detecting the flexion of a sweating hand. (c) Monitoring the EL-TENG's motion state by detecting the flexion of a sweating elbow. (d) Monitoring the EL-TENG's motion state by detecting the flexion of a sweating knee. Output current signals from the EL-TENG monitoring different human motion states, including (e) walking, (f) running, and (g) jumping. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings.

[0032] Example 1

[0033] Preparation of EL-TENG:

[0034] Ethyl cellulose (EC) with a viscosity of μ = 3-7 mPa·s (Aladdin) was prepared by dissolving EC powder in ethanol at 60°C to obtain a 10 wt% solution. Then, 5 mL of a 10 wt% solution of 3-glycidoxypropyltrimethoxysilane was mixed with 50 mL of the EC solution. Finally, reduced graphene oxide (rGO, surface area = 66 m 2 , conductivity = 19 S cm -1 ) were uniformly dispersed in the EC solution to prepare EC / rGO suspensions with mass fractions of 0, 0.1, 0.3, 0.5, 0.7 and 0.9 wt%, respectively.

[0035] The prepared suspension was poured into a polytetrafluoroethylene (PTFE) mold and then annealed in a vacuum oven at 60°C for 12 hours. The resulting EC / rGO composite film was peeled off and used as the positive triboelectric material for the TENG. The thickness of the EC / rGO film was adjusted by adjusting the depth of the grooves within the mold to vary from 0.1 mm to 1 mm.

[0036] The polydimethylsiloxane (PDMS, Sylgard 184) precursor and curing agent were mixed in a mass ratio of 10:1. Then, rGO was uniformly dispersed in the PDMS precursor to prepare PDMS / rGO suspensions with mass fractions of 0, 0.1, 0.2, 0.4, 0.6, 0.8 and 1 wt%, respectively. The prepared suspension was poured into a culture dish and dried at 60 ° C for 12 h to obtain a PDMS / rGO composite membrane. Different thicknesses were adjusted by adjusting the depth of the internal groove of the mold to adjust the thickness of different PDMS / rGO membranes 0.1mm-1mm. The obtained EC / rGO and PDMS / rGO membranes were cut into appropriate sizes (usually 3 × 3 cm 2 ), used to assemble the EL-TENG. The process is as follows:

[0037] EL-TENG is manufactured using a simple assembly process. Typically, a 3 × 3 cm 2 PDMS / rGO and EC / rGO films of varying sizes were then used as the triboelectric layers in the EL-TENG. These two triboelectric layers were bonded to two copper foils. Finally, an EL-TENG operating in contact-separation mode was assembled.

[0038] Preparation of TENG:

[0039] EC was dissolved in ethanol at 60°C to obtain a 10 wt% solution. Then, 5 mL of a 10 wt% solution of 3-glycidoxypropyltrimethoxysilane was mixed with 50 mL of the EC solution. The prepared EC suspension was poured into a PTFE mold and then annealed in a vacuum oven at 60°C for 12 h. The resulting EC film was peeled off and used as the positive triboelectric material for the TENG. The thickness of the EC film was adjusted by adjusting the depth of the grooves within the mold.

[0040] Mix the polydimethylsiloxane precursor and curing agent in a mass ratio of 10:1. Pour the prepared suspension into a Petri dish and dry it at 60°C for 12 hours to form a PDMS membrane. The thickness of the PDMS membrane can be adjusted by adjusting the depth of the grooves within the mold.

[0041] The obtained EC / PDMS membrane was cut into appropriate sizes (usually 3 × 3 cm 2 ).

[0042] 3 × 3 cm 2 The two friction layers of PDMS and EC were bonded to two copper foils. Finally, a TENG operating in contact-separation mode was assembled.

[0043] In TENG, when two friction layers come into contact with each other, contact electrification occurs at the interface, and the generated charges can be collected by an external circuit. Typically, the friction layer in TENG is usually composed of dielectric polymers, which are usually composed of polymer chains ( Figure 1 a).

[0044] Figure 1 As shown. Design and output performance of EL-TENG. (a) Schematic diagram of the device structure of a conventional dielectric TENG. The inset shows the polymer chains within the friction layer. (b) ECPW model of a conventional dielectric TENG based on EC and PDMS, with limited electron transfer at the interface. (c) Schematic diagram of the device structure of our EL-TENG. The inset shows the polymer chains within the friction layer embedded in graphene oxide. (d) Schematic diagram of the connection of the electron cloud potential wells of the EC layer and the PDMS layer in the EL-TENG through the conductive network of reduced graphene oxide (rGO) sheets, and the electron transfer at the interface is greatly enhanced. (e) Simulation of the electron density at the PDMS / rGO and EC / rGO interfaces, demonstrating the electron transfer at these interfaces. Yellow and cyan represent the positive and negative electron density differences, respectively. (fh) TENGs based on EC-PPDMS and EC / rGO-PDMS / rGO (size = 3 × 3 cm) 2 ). (f) Output voltage, (g) current, and (h) charge. (i) Output voltage and current of EL-TENG based on EC / rGO-PDMS / rGO with different thicknesses. (j) Comparison of the current density of our EL-TENG with that of reported TENGs operating in contact-separation mode.

[0045] In TENG, when two friction layers come into contact with each other, contact electrification occurs at the interface and the generated charges can be collected by an external circuit. Typically, the friction layer in TTENG is usually composed of dielectric polymers, which are usually composed of polymer chains ( Figure 1 a). Based on the ECPW model, a dielectric polymer can be viewed as multiple ECPWs, and the filling energy level of this hole (also known as the Fermi level) is related to the electron affinity of the material. Contact electrification can be explained as the transfer of electrons from the ECPW on the surface of one friction layer to the surface of another friction layer, and the partial overlap of the ECPWs of the two opposing friction layers is a prerequisite for electron transfer ( Figure 1b). On the contrary, a larger difference in the Fermi levels of the triboelectric layers will result in more charge transfer during the contact electrification process. However, the number of electrons in the ECPW is limited, and only the electrons on the surface of the triboelectric layer can promote contact electrification ( Figure 1 b).

[0046] If we can connect many ECPWs in the triboelectric layer together (especially the ECPWs inside the triboelectric layer), the generated charge and the output current of the TENG will be significantly enhanced ( Figure 1 d).

[0047] To verify our proposal, density functional theory (DFT) simulations were performed using CP2K. To reduce the required computational resources, rGO was used to represent rGO flakes and short PDMS and EC chains were used to represent long polymer chains. Electron density difference (EDD) images showed that electrons from EC can be transferred to rGO at the EC / rGO interface ( Figure 1 e), indicating that electrons from the numerous EC chains within the EC / rGO layer can accumulate and then be directed to the EC film surface via the rGO sheets. Consequently, during contact electrification, with more electrons available at the surface, improved charge transfer between the tribolayers can be achieved. Similar results were obtained in EDD images of the PDMS / rGO interface, where electrons from the PDMS can accumulate on the rGO sheets. These results confirm our hypothesis that doped graphene oxide sheets can significantly improve charge transfer from the EC to the PDMS during contact electrification.

[0048] We compared the output performance of rGO-embedded EL-TENG with that of TENG without rGO embedding ( Figure 1 f-1h). Compared with the TENG based on EC and PDMS friction pairs, the V OC Increase from 300 V to 2500 V ( Figure 1 f). In contrast, the I SC Significant increase from 60 μA to 3000 μA ( Figure 1 g), which is 50 times higher than that of the dielectric TENG based on EC-PDMS tribocouple. On the other hand, the output charge increases from 30 nC to 800 nC ( Figure 1 h), This 26.7-fold increase highlights the significant contribution of the rGO conductive network to the output charge of the EL-TENG, confirming the validity of our hypothesis.

[0049] To further confirm our hypothesis, we studied the effect of film thickness on output performance in conventional TENGs and our EL-TENG. In conventional TENGs, output performance generally decreases with increasing friction layer thickness because thinner friction layers can promote electrostatic induction. We verified this phenomenon in a TENG composed of EC and PDMS. As the friction layer thickness increases from 0.1 mm to 1 mm, V OC From 300 V to 60 V, while I SC From 80 μA to 5 μA. This is completely different in our EL-TENG. As the thickness of EC / rGO and PDMS / rGO films increases from 0.1 mm to 1 mm, the V OC It increases linearly from 1200 V to 3300 V, I SC Increases linearly from 600 μA to 4000 μA ( Figure 1 i). A film thickness of 1 mm was difficult to control, so a film thickness of 0.6 mm was subsequently adopted. The significant differences between the conventional TENG and our EL-TENG suggest that the EL-TENG has a different operating mechanism. In the EL-TENG, the thicker film connects more electron cloud potential wells, allowing for more charge transfer during contact electrification, explaining the increased output current. These results doubly confirm our hypothesis that connecting electron cloud potential wells in polymer segments can significantly increase the output current of the TENG.

[0050] In order to compare the performance of our EL-TENG with that of the reported TENG, the I SC Normalized to 3533 mAm −2 To the best of our knowledge, this current density is the highest reported for contact-separation mode TENG ( Figure 1 j). This high current density can be explained by two reasons. First, the electron affinity between EC and PDMS is large. More importantly, the connection of the electron cloud potential wells in the triboelectric layers significantly increases the amount of charge transferred from one triboelectric layer to the other.

[0051] Example 2

[0052] Embedding rGO nanosheets into the triboelectric layer can significantly improve the output performance of the corresponding TENG. Obviously, the output performance of the EL-TENG is closely related to the content of rGO nanosheets embedded in the triboelectric layer. We varied the rGO content in the range of 0-1 wt% and studied its effect on the output performance of the corresponding TENG. When the rGO content is higher than 1 wt%, agglomeration will occur in EC / PDMS, so we limited the maximum rGO content to 1 wt%. With the change of rGO content, the resistance of EC / rGO and PDMS / rGO changed significantly ( Figure 2 a). When the rGO content in the EC film increases from 0 to 0.9 wt%, the resistance of the EC / rGO film decreases significantly to 1 kΩ. This is primarily due to the formation of a conductive network at high rGO content. The conductive rGO nanosheets can connect the electron cloud potential wells of the EC polymer segments. Similarly, when the rGO content increases to 1 wt%, the resistance of the PDMS / rGO film decreases to 1 MΩ.

[0053] Subsequently, EC / rGO and PDMS / rGO films with different rGO contents were assembled into EL-TENGs operating in contact-separation mode. As the rGO content increased from 0 to 1 wt%, both the output voltage and current increased. The highest V OC (2500 V) and the highest I SC (3000 μA) ( Figure 2 b, 2c). Then, we investigated the factors that affect the output performance of EL-TENG at 1 wt% rGO content. First, the output performance of our EL-TENG depends on the initial distance between the two friction layers. As the initial distance increases from 2 to 6 mm, V OC Increase from 1000 V to 2500 V ( Figure 2 d), I SC Increased from 1200 μA to 3000 μA ( Figure 2 d). These increases are attributed to the accelerated charge transfer between the friction layers. Further increasing the initial distance weakens the electrostatic induction between the friction layer and the electrode, resulting in a decrease in output performance. Secondly, we studied the dependence of the EL-TENG output performance on the operating frequency. When the operating frequency increases from 1 Hz to 5 Hz, V OC However, as the operating frequency increases from 1 Hz to 5 Hz, I SC Gradually increase from 700 μA to 3000 μA ( Figure 2e). It is reported that the total charge in the external circuit remains constant at different operating frequencies, thus ensuring a stable output voltage. However, charge transfer is accelerated at higher frequencies, resulting in an increase in output current. Our EL-TENG also exhibits excellent stability during operation. After 5000 operating cycles, the output voltage and current have hardly changed ( Figure 2 f).

[0054] summary:

[0055] Optimal electrical performance (output voltage of 2500V and output current of 3000μA) was achieved when the PDMS solution was doped with 1wt% rGO and the EC was doped with 0.9wt% rGO, the initial distance between the friction layers was 6mm, the EC / rGO membrane thickness was 0.6mm, and the PDMS / rGO membrane thickness was 0.6mm, respectively, at an operating frequency of 5Hz. Subsequent experiments were conducted using these parameters.

[0056] Example 3

[0057] In the following Examples 3 to 5, we selected the EL-TENG prepared with the optimal parameters (doping ratio of 1%, initial distance between friction layers of 6 mm, and frequency of 5 Hz).

[0058] In the dielectric TENG, when the relative humidity (RH) increases from 20% to 60%, V OC and I SC It has dropped by about 25% ( Figure 3 a). When RH further increases to 100%, the output performance drops sharply to approximately 0. In contrast, the output voltage and current of EL-TENG remain stable even when RH increases to 100% ( Figure 3 b) shows excellent moisture resistance.

[0059] We then attempted to explore the mechanism of the excellent moisture resistance of EL-TENG. In many reports, the moisture resistance of TENGs was improved by making the friction layer surface hydrophobic. In our study, the water contact angle of the EC film embedded with rGO (mass fraction 1%) was reduced from 115° to 109° ( Figure 3 c) Compared to bare PDMS, the water contact angle of the PDMS film embedded with rGO (1% by mass) decreases from 124° to 115°. Therefore, the excellent humidity resistance of our EL-TENG cannot be explained by the hydrophobicity of the friction layer. A new mechanism must exist to explain the improved performance of our EL-TENG in humidity.

[0060] In conventional dielectric TENGs, the charge generated by contact electrification may leak into the air at high humidity due to the increase in air conductivity ( Figure 3 d). In contrast, due to the embedding of rGO conductive nanosheets ( Figure 3 e) The electrical conductivity of the EC / rGO and PDMS / rGO friction layers in our EL-TENG is greatly increased. Therefore, at high humidity, the electrical conductivity of the friction layers is much greater than that of air. Consequently, charge leakage from our EL-TENG to the air is significantly reduced, explaining its high performance and stability in high humidity and rainy environments.

[0061] Due to the new working mechanism, our EL-TENG can even work stably in rainy environments. We used a watering can to simulate light rain, moderate rain, and heavy rain. The results showed that the performance of the unencapsulated EL-TENG remained almost unchanged in light rain, moderate rain, and heavy rain ( Figure 3 f-3g). In light rain, the EL-TENG shows a V of about 2480 V. OC and about 3000 μA of I SC In the moderate rain, EL-TENG's V OC and I SC They drop slightly to about 2440 V and about 2980 μA respectively. In heavy rain, V OC and I SC The current further decreases slightly to approximately 2320 V and 2960 μA, which are 93% and 98% of those in a dry environment, respectively. These results demonstrate that the EL-TENG exhibits high stability in a rainy environment without encapsulation. To our knowledge, stable operation of conventional TENGs in rainy environments is challenging. Therefore, this unique property of our EL-TENGs significantly expands their practical applications.

[0062] Example 4

[0063] Due to the significant increase in output current / charge, our EL-TENG shows great advantages in energy harvesting. We first studied the performance of EL-TENG under different external loads. When the resistance of the external load was increased from 10 3 Ω increases to 10 9 Ω, the maximum output voltage of the EL-TENG increases from 1.5 V to 2500 V, while that of the conventional TENG based on bare EC and PDMS pairs increases from 0.1 V to 330 V. 3 Ω increases to 10 9 Ω, the maximum output current of EL-TENG is reduced from 3500 µA to 10 µA, while that of conventional TENG based on EC and PDMS pair is reduced from 70 µA to 0.6 µA ( Figure 4a, 4b). Under a 500 kΩ external load, the maximum power is 528 mW, while in the conventional TENG, only a maximum power of 2.83 mW is obtained under a 20 MΩ external load ( Figure 4 c). These results show that the maximum power achieved by the EL-TENG is 186 times that of the traditional dielectric TENG, and the optimal output is achieved under a smaller electrical load. Therefore, as an energy harvesting device, the EL-TENG can provide higher output power for electrical appliances with small loads.

[0064] Then, we demonstrated the practical applications of EL-TENG in various scenarios. First, EL-TENG charges the capacitor through the rectifier and energy management unit ( Figure 4 d). Capacitors of 100, 220, 470, and 1000 µF charge to 1.5V in 1.5, 6, 14, and 27 seconds, respectively ( Figure 4 e). Subsequently, the EL-TENG powered the appliance through a 1000 µF capacitor. The energy generated by the CE-TENG was stored in the capacitor and then used to power the electronic device ( Figure 4 f). During operation, the output voltage exhibits a sawtooth fluctuation centered at 1.5 V. Our EL-TENG also lights up a light-emitting diode (LED) via a circuit diagram with a rectifier ( Figure 4 g). Due to high performance, the size is only 3 × 3 cm 2 The EL-TENG can efficiently light up 2688 LEDs ( Figure 4 h). For comparison, we normalize the number of lit LEDs to about 300 LEDs / cm2, which is much higher than the reported TENG working in contact-separation mode (which can only light up a few to dozens of LEDs / cm2). 2 )( Figure 4 i). More importantly, the above applications can still be performed in high humidity and rainy environments. These applications show that our EL-TENG has great advantages in many applications due to its high output performance and stability.

[0065] Example 5

[0066] Our EL-TENG can also be used as a self-powered wearable sensor. It is well known that the performance of wearable sensors is significantly affected by sweat produced on human skin, especially in motion sensing. This can be very serious in some scenarios, so it is necessary to find self-powered sensors with high waterproofness. Thanks to its excellent waterproof and moisture-proof properties, our EL-TENG can be used as an excellent self-powered sensor in various scenarios. As a demonstration, we fixed the EL-TENG on different parts of the human body where sweating occurs to monitor human motion ( Figure 5 a).

[0067] We then fixed the EL-TENG on sweating human joints to sense the joint bending of the hands, elbows, and knees. First, we tested the behavior of the EL-TENG as a self-powered sensor when there was no sweat on the body surface, and found that the frequency and peak value of the triboelectric signals generated by different joint movements and different motion states of the human body were different, which is also possible in traditional TENG devices. However, since traditional TENGs are not moisture-proof, their performance is usually significantly affected by sweating conditions. In contrast, our EL-TENG is able to stably sense human motion in the presence of sweat. When the human body is sweating, an I of approximately 50 μA is observed during cyclic bending of the hand joints. SC ( Figure 5 b). A higher I of approximately 110 μA was observed during elbow joint movement. SC ( Figure 5 c). During knee joint motion, an I of approximately 200 μA was observed. SC ( Figure 5 d). In addition, by fixing the EL-TENG on the sole of the shoe, the human body's motion state can be monitored. EL-TENG successfully monitored various motion states including walking, running, and jumping ( Figure 5 e-5g). These results demonstrate that our EL-TENG is capable of converting various physiological characteristics and motor behaviors into readable, quantifiable, and real-time triboelectric signals. Therefore, our EL-TENG can be used to monitor the physiological characteristics and motor behaviors of individuals who sweat extensively, such as firefighters or astronauts. Our EL-TENG has broad application prospects in personal health monitoring, patient rehabilitation, exercise monitoring, and human motion tracking.

[0068] The present invention is not limited to the specific technical solutions described in the above embodiments, and all technical solutions formed by equivalent replacement are within the protection scope required by the present invention.

Claims

1. A method for preparing a triboelectric nanogenerator connected to an electron cloud potential well to achieve high output current, characterized in that : Includes the following steps: (1) Reduced graphene oxide (rGO) was uniformly dispersed in an ethyl cellulose (EC) solution to prepare an EC / rGEC / rGO suspension with a mass fraction of 0.5-0.9 wt%. The prepared suspension was poured into a polytetrafluoroethylene (PTFE) mold and then annealed in a vacuum oven. The obtained EC / rGO composite film was peeled off and used as the positive triboelectric material of TENG. (2) Dispersing rGO uniformly in a polydimethylsiloxane (PDMS) precursor to prepare a PDMS / rGO suspension with a mass fraction of 0.4–1 wt %. Pour the prepared suspension into a Petri dish and dry it to obtain a PDMS / rGO composite film as the triboelectric material for the TENG. (3) Cutting the obtained EC / rGO and PDMS / rGO membranes into appropriate sizes; (4) PDMS / rGO and EC / rGO films cut into appropriate sizes are used as the triboelectric layers in EL-TENG. The two triboelectric layers are glued to two copper foils and assembled into a triboelectric nanogenerator EL-TENG that works in contact-separation mode and connects the electron cloud potential well to achieve high output current. EC was dissolved in ethanol at 60°C to obtain a 10 wt% solution. 5 mL of a 10 wt% 3-glycidoxypropyltrimethoxysilane solution was mixed with 50 mL of the EC solution. Reduced graphene oxide was evenly dispersed in the EC solution to prepare EC / rGO suspensions with mass fractions of 0.5, 0.7, and 0.9 wt%, respectively. The prepared suspensions were poured into a polytetrafluoroethylene mold and then annealed in a vacuum oven at 60°C for 12 h. The resulting EC / rGO composite film was peeled off and used as the positive triboelectric material for the TENG. The thickness of the different EC / rGO films was adjusted by adjusting the depth of the internal groove of the mold to 0.1 mm to 1 mm. The rGO was uniformly dispersed in the PDMS precursor to prepare PDMS / rGO suspensions with mass fractions of 0.4, 0.6, 0.8, and 1 wt %, respectively. The prepared suspensions were poured into a Petri dish and dried at 60°C for 12 h to obtain PDMS / rGO composite membranes. The thickness of the different PDMS / rGO membranes was adjusted by adjusting the depth of the internal groove of the mold to 0.1 mm-1 mm. The obtained EC / rGO and PDMS / rGO membranes were cut into appropriate sizes of 3 × 3 cm. 2 ; 3 × 3 cm 2 The PDMS / rGO and EC / rGO films of different sizes were then used as the triboelectric layers in the EL-TENG, and the two triboelectric layers were glued onto two pieces of copper foil to assemble into an EL-TENG working in contact-separation mode.

2. The method for preparing a triboelectric nanogenerator for connecting an electron cloud potential well to achieve high output current according to claim 1, characterized in that: Ethyl cellulose EC, viscosity μ = 3-7 mPa·s, polydimethylsiloxane PDMS, Sylgard184.

3. The method for preparing a triboelectric nanogenerator for achieving high output current by connecting an electron cloud potential well according to claim 1, characterized in that: Reduced graphene oxide rGO, specific surface area = 66 m 2 , conductivity = 19 S cm -1 .

4. The method for preparing a triboelectric nanogenerator for achieving high output current by connecting an electron cloud potential well according to claim 1, characterized in that: When the proportion of rGO doped in PDMS solution is 1wt%, the thickness of EC / rGO membrane is 0.6mm, the thickness of PDMS / rGO membrane is 0.6mm, and the proportion of rGO doped in EC is 0.9 wt%, the initial distance between the friction layers is 6mm, the operating frequency is 5Hz, and the output voltage of the prepared friction nanogenerator is 2500V and the output current is 3000 μA.

5. A triboelectric nanogenerator prepared by connecting electron cloud potential wells to achieve high output current according to any one of claims 1 to 4.

6. Application of the triboelectric nanogenerator for achieving high output current by connecting electron cloud potential wells according to claim 5, characterized in that: Applications in high humidity environments and in rain.

7. The application of the triboelectric nanogenerator for achieving high output current by connecting electron cloud potential wells according to claim 5, characterized in that: Applications include efficient energy harvesting and self-powered motion sensing in rain.

8. The application of the triboelectric nanogenerator for achieving high output current by connecting electron cloud potential wells according to claim 5, characterized in that: It is used in the fields of personal health monitoring, patient rehabilitation, sports monitoring and human motion tracking.

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