A micro-arc oxidation-based droplet power generation device and application thereof

Abstract

This invention belongs to the field of nanogenerator technology, and more specifically relates to a droplet power generation device based on micro-arc oxidation and its application. The droplet power generation device based on micro-arc oxidation provided by this invention includes: a first conductive element, a micro-arc oxidation insulating layer, a hydrophobic insulating layer, a second conductive element, and an external circuit system. This invention, through the innovative integration of the micro-arc oxidation insulating layer, successfully fabricates a high-performance, highly stable, and environmentally adaptable droplet power generation device. This device effectively solves the problems of low power generation, poor interfacial bonding, and insufficient long-term stability in existing technologies, and demonstrates complete application capabilities from energy harvesting to practical driving, possessing significant application value in the fields of micro-nano energy harvesting and self-powered sensing.

Description

Technical Field

[0001] This invention belongs to the field of nanogenerator technology, and more specifically relates to a droplet power generation device based on micro-arc oxidation and its application. Background Technology

[0002] Hydropower, as one of the most abundant energy sources on Earth's surface (covering over 70%), especially in the form of water droplets, tides, and waves, has not yet been fully developed. In recent years, various hydropower harvesting technologies have emerged, such as piezoelectric nanogenerators, hydrovoltaic technology, reverse electrodialysis, thermoelectric technology, and triboelectric nanogenerators. However, these technologies are generally limited by the inherent defects of interface effects in charge generation and transport processes, resulting in low energy conversion efficiency. Although droplet generators (DEGs) based on bulk effect-enhanced charge transport have achieved orders-of-magnitude improvements in output voltage, transferred charge, and energy density, existing droplet generators still suffer from bottlenecks such as low power generation, poor interfacial bonding strength, complex manufacturing processes, and difficulty in large-scale production.

[0003] Micro-arc oxidation (MAO), as an emerging surface treatment technology, offers a new approach to solving the aforementioned problems. This technology can grow ceramic oxide layers in situ on the surfaces of valve metals such as aluminum, magnesium, and titanium. The film formation process involves spark discharge in the electrolyte, cycling through "breakdown discharge - melting sintering - rapid cooling solidification" to ultimately form a uniform ceramic film. Compared with traditional anodizing, MAO has significant advantages: First, the coating thickness, surface morphology, porosity, and micropore size are controllable, allowing for precise regulation of film characteristics by adjusting electrolyte composition and electrical parameters. Second, the process is simple and efficient, with no special requirements on workpiece shape, and the electrolyte is weakly alkaline, making it environmentally friendly. Third, the resulting ceramic film exhibits strong adhesion to the substrate, excellent wear resistance, corrosion resistance, and insulation properties. These characteristics make MAO particularly suitable for processing components requiring high wear and corrosion resistance, such as high-speed moving parts in aerospace, military, and machinery industries.

[0004] However, directly applying micro-arc oxidation technology to droplet generators still faces challenges. On the one hand, the hydrophobicity and surface charge stability of the micro-arc oxidation film need further optimization to meet the high requirements of dynamic changes in interfacial contact area in droplet power generation. On the other hand, in existing droplet generators, the interfacial bonding strength between the hydrophobic insulating layer and the substrate is insufficient, making it susceptible to environmental influences and leading to a decrease in charge transfer efficiency. Furthermore, electrolyte temperature control and energy consumption issues during micro-arc oxidation also restrict its large-scale application. Therefore, developing a droplet power generation device integrating a micro-arc oxidation insulating layer, leveraging its superior film performance to improve power generation efficiency and stability, has become a key direction for overcoming current technological bottlenecks. Summary of the Invention

[0005] The purpose of this invention is to provide a droplet power generation device based on micro-arc oxidation and its application, so as to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] One of the technical solutions of the present invention is to provide a droplet power generation device based on micro-arc oxidation, comprising: a first conductive element, a micro-arc oxidation insulating layer, a hydrophobic insulating layer, a second conductive element, and an external circuit system;

[0008] The micro-arc oxidation insulating layer is located on the surface of the first conductive element;

[0009] The hydrophobic insulating layer is located on the surface of the micro-arc oxidation insulating layer;

[0010] The second conductive element is disposed above the hydrophobic insulating layer;

[0011] The external circuit system is used to connect the first conductive element and the second conductive element.

[0012] In the external circuit system, the voltage, charge, or current parameters on the path are detected by an electrical signal detection unit. This unit, together with the first conductive element and the second conductive element, forms a closed loop.

[0013] Furthermore, the first conductive element or the second conductive element is made of a material with conductive properties.

[0014] Optionally, the first conductive element includes one of aluminum, copper alloy, stainless steel, aluminum alloy, magnesium alloy, and titanium alloy.

[0015] Optionally, the second conductive element includes one of stainless steel, aluminum, copper, aluminum alloy, magnesium alloy, and titanium alloy.

[0016] This invention enables the in-situ growth of oxide ceramic coatings on the surfaces of metals such as aluminum, titanium, and magnesium through micro-arc oxidation (MAO), which can effectively improve the physicochemical properties of alloy surfaces.

[0017] The present invention does not specifically limit the structure and physical form of the first or second conductive element, which can be a conductive electrode sheet, a conductive plate, etc.

[0018] Furthermore, the preparation step of the micro-arc oxidation insulating layer includes: after pretreating the first conductive element, performing micro-arc oxidation (MAO) treatment in an electrolyte to generate the micro-arc oxidation insulating layer in situ on the surface of the first conductive element.

[0019] Optionally, the pretreatment includes: after the first conductive element is polished, it is ultrasonically cleaned in acetone, ethanol and water for 3 minutes each, and then dried.

[0020] Optionally, the parameters of the micro-arc oxidation (MAO) treatment include: voltage 350-480V, frequency 1000Hz, duty cycle 20%, and treatment time 5min.

[0021] Optionally, the electrolyte comprises 15 g / L sodium silicate and 3 g / L sodium hydroxide, with an initial temperature of 25 ± 2 °C.

[0022] This invention utilizes micro-arc oxidation technology to achieve in-situ generation of a micro-arc oxidized insulating layer (ceramic coating) on ​​the surface of a first conductive element at a relatively low process temperature. This results in minimal thermal impact on the first conductive element, and the micro-arc oxidized insulating layer exhibits advantages such as strong adhesion to the aluminum alloy substrate of the first conductive element, high uniformity of element distribution, and no interface contamination or oxidation loss. Furthermore, the rough surface produced by micro-arc oxidation technology enhances the interfacial bonding strength with the hydrophobic insulating layer and improves the overall corrosion resistance of the device.

[0023] Furthermore, the hydrophobic insulating layer is made of a hydrophobic insulating material with surface charge.

[0024] The surface charge of the hydrophobic insulating layer of this invention can be obtained through corona discharge or triboelectric charging.

[0025] Optionally, the hydrophobic insulating material with surface charge includes a fluoropolymer material with low surface energy.

[0026] Preferably, the low surface energy fluoropolymer material includes polytetrafluoroethylene, fluorinated ethylene propylene, or amorphous fluoropolymers.

[0027] The second technical solution of the present invention provides an application of the above-mentioned droplet power generation device based on micro-arc oxidation in the field of power generation.

[0028] The third technical solution of the present invention provides a power generation method, which converts electrical energy using the above-mentioned droplet power generation device based on micro-arc oxidation, and includes the following steps:

[0029] The conductive liquid is dripped onto the surface of the hydrophobic insulating layer of the droplet power generation device based on micro-arc oxidation;

[0030] The conductive liquid spreads on the surface of the hydrophobic insulating layer and comes into contact with the second conductive element, generating an electrical signal in the external circuit.

[0031] During the dripping process, the droplet lands on the surface of the hydrophobic insulating layer. Initially, the droplet does not contact the second conductive element, and the circuit is open. After the droplet impacts the hydrophobic insulating layer, it spreads. During this process, the droplet interacts with the hydrophobic insulating layer, which carries a surface charge due to corona discharge or triboelectric charging, forming a solid-liquid contact surface. When the droplet spreads to simultaneously contact the hydrophobic insulating layer and the second conductive element, the previously open circuit becomes conductive, forming a complete conductive path between the first conductive element, the micro-arc oxidized insulating layer, the hydrophobic insulating layer, the droplet, and the second conductive element. At the instant the circuit is opened, due to the rapid change in the interface charge distribution, the accumulated charge (especially the charge stably stored through the strong bond between the micro-arc oxidation insulating layer and the substrate) is rapidly transferred through the droplet bridging path. This generates a momentary pulse current or voltage signal in the external circuit connecting the first and second conductive elements. After the charge transfer is complete, the droplet slides off the surface of the hydrophobic insulating layer under the influence of gravity, separating from the second conductive element, and the circuit returns to an open circuit state. At this time, the surface charge distribution is readjusted, preparing for the impact of the next droplet and the next power generation cycle. By continuously dropping droplets, an electrical signal can be continuously output, realizing the continuous conversion of mechanical energy into electrical energy. In summary, conductive liquid drips onto the surface of the hydrophobic insulating layer; the conductive liquid contacts the second conductive element on the hydrophobic insulating layer, and through its spreading and sliding on the surface of the hydrophobic insulating layer, the area of ​​the surface charge contact surface changes, thereby generating an electrical signal between the first and second conductive elements, which is then output through the external circuit.

[0032] The surface charge contact surface refers to the overlapping portion of the pattern formed by the surface charge on the hydrophobic insulating layer, the solid-liquid contact surface formed by the conductive liquid and the hydrophobic insulating layer. In other words, it is the local contact surface between the conductive liquid and the hydrophobic insulating layer where the surface charge is located. The contact between the conductive liquid on the hydrophobic insulating layer and the second conductive element, causing a change in the area of ​​the surface charge contact surface, means that at least contact occurs between the conductive liquid and the second conductive element, and simultaneously, the size of the local contact surface between the conductive liquid and the hydrophobic insulating layer where the surface charge is located changes. Additionally, in some cases, separation may also occur.

[0033] The relative movement between the conductive liquid on the hydrophobic insulating layer and the second conductive element is a relative displacement between them. This displacement can be any two or more of the following states: contact between the conductive liquid and the second conductive element at the boundary of the hydrophobic insulating layer; the contact area between the conductive liquid and the second conductive element gradually increases; the contact area between the conductive liquid and the second conductive element reaches its maximum; the contact area between the conductive liquid and the second conductive element gradually decreases; and the conductive liquid and the second conductive element disengage.

[0034] Furthermore, the surface of the hydrophobic insulating layer of the droplet power generation device based on micro-arc oxidation is inclined at an angle of 10° to 80° with the horizontal plane, preferably at an angle of 45°.

[0035] Furthermore, the parameters for the conductive liquid droplet include: flow rate of 5-15 mL / min, droplet height of 10-20 cm, and volume of a single droplet of 90-100 μL.

[0036] Optionally, the parameters for the conductive liquid droplet include: a flow rate of 10 mL / min, a droplet height of 15 cm, and a single droplet volume of 100 μL.

[0037] Furthermore, the conductive liquid includes at least one of electrolyte liquid, ionic liquid, liquid metal, and nanometal solution.

[0038] Optionally, the conductive liquid includes tap water, NaCl solution, KCl ionic liquid, liquid mercury, liquid amalgam, liquid gallium alloy, or nano silver paste.

[0039] For cost reasons, the conductive liquid is preferably an electrolyte liquid.

[0040] The present invention discloses the following technical effects:

[0041] This invention introduces a micro-arc oxidation (MAO) insulating layer as an intermediate layer in a droplet power generation device, which greatly enhances the electrical output capability of the MAO-DEG device. The MAO insulating layer and the first conductive element are grown in situ, resulting in strong adhesion. Its unique porous interconnected ceramic structure provides effective trapping and storage sites for charges, optimizing the interfacial charge distribution. The resulting MAO insulating layer exhibits excellent insulation and corrosion resistance, effectively preventing electrolyte penetration. This significantly increases the charge transfer resistance of the first conductive element and reduces the corrosion current density, thereby ensuring the long-term electrochemical stability of the power generation interface in humid or electrolyte environments.

[0042] The micro-arc oxidation process parameters of the present invention are clear and the performance is controllable and adjustable. The droplet power generation device containing the micro-arc oxidation (MAO) insulating layer has excellent operational stability and durability, meets the needs of practical applications, has high-performance power generation capability, and has practical application potential to drive microelectronic devices and build self-powered systems.

[0043] This invention innovatively integrates a micro-arc oxidation insulating layer to successfully fabricate a high-performance, highly stable, and environmentally adaptable droplet power generation device. This device effectively solves problems such as low power generation, poor interfacial bonding, and insufficient long-term stability in existing technologies, and demonstrates complete application capabilities from energy harvesting to practical driving, possessing significant application value in the fields of micro-nano energy harvesting and self-powered sensing. Attached Figure Description

[0044] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0045] Figure 1 The diagram shows the structure and cross-sectional SEM image of the droplet power generation device (MAO-DEG) prepared in Example 1.

[0046] Figure 2 This is a physical image of the MAO-DEG in Example 1.

[0047] Figure 3 The diagram shows the structural schematic and cross-sectional SEM image of DEG in Comparative Example 1.

[0048] Figure 4 This is a schematic diagram of the apparatus for the micro-arc oxidation process in Example 1.

[0049] Figure 5 This is a schematic diagram of the preparation process of the AF hydrophobic insulating layer and MAO-Al in Example 1.

[0050] Figure 6 The images show SEM images of the micro-arc oxidized insulating layer (left) and the Al electrode without micro-arc oxidation (right) in Example 1.

[0051] Figure 7 This is a schematic diagram illustrating the power generation principle of the droplet power generation device based on micro-arc oxidation according to the present invention.

[0052] Figure 8 The image shows the EDS energy spectrum of the micro-arc oxidation insulating layer in Example 1.

[0053] Figure 9 This is the XPS full spectrum of the micro-arc oxidation insulating layer in Example 1.

[0054] Figure 10 A comparison of the output performance of DEG and MAO-DEG.

[0055] Figure 11 The dynamic response of the electrical output performance of MAO-DEG and DEG is compared. In this paper, a is the curve of output voltage changing with time, b is the curve of transferred charge changing with time, and c is the curve of output current changing with time.

[0056] Figure 12The image shows the effect of the micro-arc oxidation (MAO) voltage on the performance of the droplet power generation device in Examples 1-2 and Comparative Example 2. In the image, a represents the change in output voltage with MAO voltage, b represents the change in transferred charge with MAO voltage, c represents the change in output energy and efficiency with MAO voltage, d represents the change in device capacitance with MAO voltage, e represents the SEM image of the micro-arc oxidation insulating layer when the MAO voltage is 400V, and f represents the SEM image of the micro-arc oxidation insulating layer when the MAO voltage is 480V.

[0057] Figure 13 An equivalent circuit model of the electrochemical impedance spectroscopy of an aluminum alloy plate with a micro-arc oxidation insulating layer in NaCl solution.

[0058] Figure 14 Electrochemical impedance spectroscopy analysis of the effect of micro-arc oxidation treatment on the corrosion resistance of aluminum substrate (1060 aluminum alloy plate). In the figure, a is the impedance complex plane spectrum of Al and Ceramic coating, b is the impedance modulus as a function of frequency, and c is the phase angle as a function of frequency.

[0059] Figure 15 To illustrate the effect of micro-arc oxidation treatment on the corrosion behavior of the aluminum substrate, where a represents the potentiodynamic polarization curves of Al (1060 aluminum alloy plate) and ceramic coating in NaCl solution, and b represents the corrosion potential (E) obtained by fitting the polarization curves. corr ) and corrosion current density (I corr )contrast.

[0060] Figure 16 To characterize the electrical output performance of the droplet power generation device under different conductive liquid conditions, where a is the effect of different conductive liquids on the output voltage of the droplet power generation device (Example 1), b is the effect of the first conductive element of different materials (Examples 1 and 3) on the output voltage of the droplet power generation device (tap water), c is the effect of the external load resistor on the output characteristics of the droplet power generation device (tap water), and d is the long-term stability test of the output voltage of the droplet power generation device (tap water) in Example 1.

[0061] Figure 17 This document demonstrates the system configuration, output performance, and application of the MAO-DEG (Example 1) energy harvesting device. Specifically, a is a photograph of the prototype MAO-DEG energy harvesting device; b is the charging curve of the MAO-DEG under different capacitors; c is the light emission diagram of the MAO-DEG directly driving the LED array; d is the circuit diagram of the MAO-DEC energy management and sensing system; e is the operating voltage curve of the MAO-DEG powering a wireless temperature sensor; and f is the operating voltage curve of the MAO-DEG powering a calculator.

[0062] Figure 18The transient voltage response and energy output characteristics of the MAO-DEG. Detailed Implementation

[0063] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0064] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0065] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0066] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0067] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0068] Unless otherwise specified, all raw materials and reagents involved in the specific embodiments of this invention are commercially available products.

[0069] Unless otherwise specified, room temperature and normal temperature in the specific embodiments of this invention refer to 20-30℃.

[0070] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0071] Example 1

[0072] A droplet power generation device based on micro-arc oxidation includes:

[0073] The first conductive element (1060 aluminum alloy plate), micro-arc oxidation insulation layer (Ceramic coating), hydrophobic insulation layer (AF hydrophobic insulation layer), second conductive element (304 stainless steel needle) and external circuit system;

[0074] A 1060 aluminum alloy plate with dimensions of 30mm×30mm×0.5mm was polished to a surface roughness of 400nm, and then ultrasonically cleaned for 3 minutes each in acetone, anhydrous ethanol, and deionized water, and finally dried to obtain a pretreated aluminum alloy plate.

[0075] A pretreated aluminum alloy plate was used as the anode, clamped and fixed with aluminum strips, and immersed in an electrolyte (2L) prepared with sodium silicate (15 g / L) and sodium hydroxide (3 g / L). The initial temperature of the electrolyte was controlled at 25±2℃. The micro-arc oxidation equipment was turned on and set to constant voltage mode, and treated for 5 minutes at a voltage of 400V, a frequency of 1000Hz, and a duty cycle of 20%. After treatment, the sample was immediately removed, rinsed with deionized water, and dried to obtain an aluminum alloy plate with an in-situ micro-arc oxidation insulating layer on its surface (denoted as MAO-Al).

[0076] Dissolve 1.14 g of Chemours Teflon™ AF 1600 in 10 mL of perfluorinated solvent FC-40 and stir magnetically for 3.5 hours (750 rpm, 60°C) to prepare a 6 wt% AF solution. Use a pipette to drop 345 μL of the above AF solution onto an aluminum alloy plate on which a micro-arc oxide insulating layer is formed in situ. Allow it to level naturally, then preheat it on a hot plate at 85°C for 15 min to evaporate the solvent and avoid generating bubbles during curing. Then transfer it to a vacuum drying oven at 120°C for 60 min to form an AF hydrophobic insulating layer (AF hydrophobic insulating layer is generally referred to as PTFE) on the surface of the micro-arc oxide insulating layer.

[0077] A 304 stainless steel needle is placed on the AF hydrophobic insulating layer as the top electrode. Then, copper wires are used to connect the Al alloy electrode (aluminum alloy plate) and the stainless steel needle electrode to obtain the droplet power generation device, denoted as MAO-DEG.

[0078] Example 2

[0079] The only difference compared to Example 1 is that the voltage of the micro-arc oxidation process is adjusted from 400V to 380V.

[0080] Example 3

[0081] Compared with Example 1, the only difference is that the material of the second conductive element is changed from stainless steel to 1060 aluminum alloy plate (Al) or Cu.

[0082] Comparative Example 1

[0083] Compared with Example 1, the difference is that a micro-arc oxidation insulating layer is not set. The specific steps are as follows:

[0084] The droplet power generation device includes: a first conductive element (1060 aluminum alloy plate), a hydrophobic insulating layer (AF hydrophobic insulating layer), a second conductive element (304 stainless steel needle), and an external circuit system.

[0085] A 1060 aluminum alloy plate with dimensions of 30 mm × 30 mm × 0.5 mm was polished to a surface roughness of 400 nm, and then ultrasonically cleaned for 3 min each in acetone, anhydrous ethanol, and deionized water, and then dried to obtain a pretreated aluminum alloy plate.

[0086] 1.14g Chemours Teflon TM AF 1600 was dissolved in 10 mL of perfluorinated solvent FC-40 and magnetically stirred for 3.5 hours (750 rpm, 60℃) to prepare a 6 wt% AF solution. 345 μL of the above AF solution was dropped onto the pretreated aluminum alloy plate using a pipette and allowed to level naturally. The plate was then preheated at 85℃ for 15 min to evaporate the solvent and prevent the formation of bubbles during curing. Finally, the plate was transferred to a vacuum drying oven at 120℃ for 60 min to form an AF hydrophobic insulating layer on the surface of the pretreated aluminum alloy plate.

[0087] A 304 stainless steel needle is placed on the AF hydrophobic insulating layer as the top electrode. Then, copper wires are used to connect the Al alloy electrode (aluminum alloy plate) and the stainless steel needle electrode to obtain the droplet power generation device, denoted as DEG.

[0088] Comparative Example 2

[0089] Compared with Example 1, the only difference is that the voltage of the micro-arc oxidation process is adjusted from 400V to 0V, 350V, 450V or 480V.

[0090] Test case

[0091] Figure 1The figures show a schematic diagram and a cross-sectional SEM image of the droplet power generation device (MAO-DEG) prepared in Example 1. As shown, the device comprises a first conductive element, a micro-arc oxide insulating layer (ceramic coating), a hydrophobic insulating layer (PTFE), and a second conductive element. The first conductive element is made of 1060 aluminum alloy (Al). The micro-arc oxide insulating layer is formed on the surface of the first conductive element, and the hydrophobic insulating layer covers the surface of the micro-arc oxide insulating layer. The second conductive element is placed on the surface of the hydrophobic insulating layer. The conductive liquid is in contact with both the hydrophobic insulating layer and the electrode. A scanning electron microscope image of the cross-section of the droplet power generation device is also shown, clearly displaying the three-layer structure of the first conductive element, the micro-arc oxide insulating layer, and the hydrophobic insulating layer, with uniform thickness distribution in each layer.

[0092] Figure 2 This is a physical image of the MAO-DEG in Example 1.

[0093] Figure 3 The diagram shows the structural schematic and cross-sectional SEM image of DEG in Comparative Example 1.

[0094] Figure 4 This is a schematic diagram of the apparatus for the micro-arc oxidation process in Example 1.

[0095] Figure 5 This is a schematic diagram of the preparation process of the AF hydrophobic insulating layer and MAO-Al in Example 1.

[0096] Figure 6 The images show SEM images of the micro-arc oxidized insulating layer (left) and the Al electrode without micro-arc oxidization (right) in Example 1.

[0097] Figure 7 This is a schematic diagram illustrating the power generation principle of the droplet power generation device based on micro-arc oxidation of this invention. It visually demonstrates the existence of surface charges on the hydrophobic insulating layer. The uniform distribution or controllable aggregation of surface charges is the basis for their charge interaction with the conductive liquid, providing visual support for the charge separation and transmission mechanism of the power generation device and explaining one of the core principles of the device's power generation.

[0098] Figure 8 The image shows the EDS spectrum of the micro-arc oxidation insulating layer in Example 1. As can be seen from the image, in addition to the characteristic peaks of aluminum, the micro-arc oxidation insulating layer (MAO-Al) also exhibits obvious characteristic peaks of oxygen (O) and silicon (Si). This is consistent with the electrolyte used in the micro-arc oxidation process (containing sodium silicate and sodium hydroxide), proving that a ceramic-based insulating layer containing aluminum, oxygen, and silicon has been successfully formed on the surface of the 1060Al substrate through micro-arc oxidation treatment. This provides elemental-level structural verification for the subsequent attachment of hydrophobic insulating layers and the insulation performance of the power generation device.

[0099] Figure 9 The image shows the XPS full spectrum of the micro-arc oxidation insulating layer in Example 1. As can be seen from the image, the XPS full spectrum of the 1060 aluminum alloy plate (Al) only shows characteristic peaks of aluminum (such as Al 2p, Al 2s, etc., corresponding to specific binding energy ranges), and no obvious peaks of other impurity elements were detected, confirming the purity characteristics of the 1060 aluminum alloy plate as a high-purity industrial pure aluminum alloy (aluminum content ≥99.6%). In the full spectrum of the micro-arc oxidation insulating layer (MAO-Al), in addition to retaining the characteristic peaks of aluminum, significant characteristic peaks of oxygen and silicon were added. A small amount of carbon peaks may originate from environmental residues or the sample processing. These characteristics are completely consistent with the design of the micro-arc oxidation process in the invention. Figure 8 (EDS elemental analysis) corroborates each other, further confirming the successful preparation of the micro-arc oxidation insulating layer at the chemical state level.

[0100] The droplet power generation devices in the embodiments and comparative examples were subjected to the following power generation experiments, and an electrical signal detection unit was set on the external circuit system to detect voltage, charge, or current parameters in the path. The steps included:

[0101] Conductive liquid: tap water;

[0102] The surface of the hydrophobic insulating layer of the droplet power generation device is inclined at a 45° angle to the horizontal plane;

[0103] The parameters for the conductive liquid droplet are: flow rate 10 mL / min, droplet height 15 cm, and single droplet volume 100 μL.

[0104] Figure 10 This figure compares the output performance of DEG and MAO-DEG. The comparison shows that the electrical performance indicators (energy and energy conversion efficiency) of MAO-DEG are higher than those of DEG, indicating that the introduction of the micro-arc oxidation insulating layer has a positive effect on improving electrical performance.

[0105] Figure 11 The dynamic response of the electrical output performance of MAO-DEG and DEG is compared. Figure a shows the output voltage versus time, figure b shows the transferred charge versus time, and figure c shows the output current versus time. As can be seen from the figure, the peak open-circuit voltage and peak short-circuit current of DEG are 138V and 688μA, respectively. In contrast, the peak open-circuit voltage of MAO-DEG increases to 208V, an increase of 50.7%, and the peak short-circuit current increases to 896μA, an increase of 30.2%. Furthermore, the transferred charge increases from 51.2 nC in DEG to approximately 64 nC in MAO-DEG, an increase of 25%. This significant performance improvement directly confirms the effectiveness of the micro-arc oxide insulating layer as an intermediate layer in enhancing the triboelectric output performance of the device.

[0106] Figure 12 The figures illustrate the effect of micro-arc oxidation (MAO) voltage on the performance of droplet power generation devices in Examples 1-2 and Comparative Example 2. Figure a shows the change in output voltage with MAO voltage, b shows the change in transferred charge with MAO voltage, c shows the change in output energy and efficiency with MAO voltage, d shows the change in device capacitance with MAO voltage, e shows the SEM image of the micro-arc oxidation insulating layer at a MAO voltage of 400V, and f shows the SEM image of the micro-arc oxidation insulating layer at a MAO voltage of 480V. As shown in the figures, the output voltage and transferred charge initially increase and then decrease with increasing MAO voltage, reaching a peak at 400V. Simultaneously, the corresponding output energy and conversion efficiency also follow the same trend, reaching maximum values ​​of 8.31μJ and 5.66%, respectively, at 400V. The capacitance increases with increasing MAO voltage, reaching a maximum of approximately 0.12nF at 400V. When the voltage exceeds 400V, the capacitance decreases. This trend corresponds to the electrochemical performance trend (…). Figure 12 The results in (a) to (c) are completely consistent, confirming that 400V is the ideal voltage parameter for optimizing interfacial charge storage capability. In (e), at a MAO processing voltage of 400V, the MAO layer exhibits a dense, porous structure with abundant pores, which is beneficial for charge trapping and storage. In (f), when the processing voltage deviates to 480V, the MAO layer structure breaks down, the number of pores decreases, and the interfacial charge storage capability weakens accordingly. In summary, these results establish an intrinsic relationship between MAO voltage-induced MAO layer structure evolution and device charge storage performance.

[0107] Figure 13 An equivalent circuit model of the electrochemical impedance spectroscopy of an aluminum alloy plate with a micro-arc oxidation insulating layer in NaCl solution.

[0108] Figure 14 Electrochemical impedance spectroscopy (EIS) analysis was performed to investigate the effect of micro-arc oxidation treatment on the corrosion resistance of an aluminum substrate (1060 aluminum alloy plate). Figure a shows the complex plane impedance spectrum of Al and the ceramic coating; figure b shows the impedance modulus as a function of frequency; and figure c shows the phase angle as a function of frequency. The figures show that in figure a, the impedance arc radius of the ceramic coating is significantly larger than that of the 1060 aluminum alloy plate, indicating that after the formation of the micro-arc oxidation insulating layer, the charge transfer impedance increases, the coating exhibits excellent density, and it can effectively block the penetration of corrosive media. In figure b, the ceramic coating shows a higher and more stable impedance modulus in the low-to-mid frequency range, indicating superior insulation performance. In figure c, the peak phase angle of the ceramic coating is closer to 90° and has a wider stable range, confirming the capacitive characteristics of its ceramic-based coating and further demonstrating the strong bond between the coating and the substrate, and reliable insulation performance.

[0109] Figure 15 To illustrate the effect of micro-arc oxidation treatment on the corrosion behavior of the aluminum substrate, where a represents the potentiodynamic polarization curves of Al (1060 aluminum alloy plate) and ceramic coating in NaCl solution, and b represents the corrosion potential (E) obtained by fitting the polarization curves. corr ) and corrosion current density (I corr (Comparison) As shown in Figure a, the corrosion current density of the ceramic coating is significantly lower than that of the 1060 aluminum alloy plate, and the corrosion potential is positively shifted, indicating that the micro-arc oxidation insulating layer can effectively inhibit substrate corrosion and improve corrosion resistance. Figure b shows that the ceramic coating exhibits typical n-type semiconductor characteristics, and the slope of the curve reflects the space charge layer capacitance characteristics, indicating that the semiconductor characteristics of the ceramic coating help to regulate charge transfer behavior and provide structural support for charge storage and transport in power generation devices.

[0110] In the power generation experiment, the conductive liquid was adjusted to seawater, rainwater, tap water, and deionized water, and its electrical output performance in the droplet power generation device was compared.

[0111] Figure 16 To characterize the electrical output performance of the droplet generator under different conductive liquid conditions, the figures are as follows: a) shows the effect of different conductive liquids on the output voltage of the droplet generator (Example 1); b) shows the effect of different materials of the second conductive element (Examples 1 and 3) on the output voltage of the droplet generator (tap water); c) shows the effect of the external load resistance on the output characteristics of the droplet generator (tap water); and d) shows the long-term stability test of the output voltage of the droplet generator (tap water) in Example 1. As shown in the figures, in a), the voltage output results of the droplet generator in Example 1 under seawater, rainwater, tap water, and deionized water show that the voltage output is more stable in the tap water and seawater systems. In b, the output voltage changes of the droplet generators in Examples 1 and 3 using tap water as the conductive liquid show that the material of the second conductive element has virtually no effect on the electrical output. c reflects the effect of the external circuit resistance on the output voltage; the resistance is 10... 5 ~10 8 The voltage output reaches its peak value in the Ω range, providing parameter reference for external circuit design. Figure d shows the voltage fluctuation of the droplet generator during 160 minutes of continuous operation; the fluctuation amplitude is less than 10%, demonstrating its stability during long-term operation and meeting the durability requirements of practical applications.

[0112] Figure 17This document demonstrates the system configuration, output performance, and application of the MAO-DEG (Example 1) energy harvesting device. Figure a shows a prototype photograph of the MAO-DEG energy harvesting device; figure b shows the charging curves of the MAO-DEG with different capacitors; figure c shows the light emission diagram of the MAO-DEG directly driving the LED array; figure d shows the circuit diagram of the MAO-DEG energy management and sensing system; figure e shows the operating voltage curve of the MAO-DEG powering a wireless temperature sensor; and figure f shows the operating voltage curve of the MAO-DEG powering a calculator. As can be seen from the figure, figure b compares the charging processes of four capacitors: 2.2μF, 4.7μF, 10μF, and 22μF. The 10μF capacitor exhibits the fastest charging rate and the highest peak voltage, further providing a reference for capacitor selection in the device's energy storage module. In AB and EF, the complete application process of the droplet power generation device from "generating electrical energy" to "driving the load" is demonstrated, breaking the limitations of only being able to test electrical performance in the laboratory. The supply voltage (1.0~1.5V) is highly matched with the working voltage of the micro sensor, proving that the device can be directly connected to existing microelectronic devices without the need for an additional voltage regulation module. The voltage fluctuation amplitude during the power supply stage is less than 0.2V, which is far below the voltage tolerance threshold of the sensor, reflecting the stability of the system's power supply to the load and laying the foundation for long-term practical application.

[0113] Figure 18 The transient voltage response and energy output characteristics of the MAO-DEG are shown in the figure. As can be seen from the figure, the single-cycle power generation performance of the device is quantified. The energy output and conversion efficiency indicators prove its practical application potential and provide a quantitative reference standard for subsequent optimization of power generation device structure and performance improvement.

[0114] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0115] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A micro-arc oxidation based droplet power generation device, characterized by, include: The system comprises a first conductive element, a micro-arc oxidation insulating layer, a hydrophobic insulating layer, a second conductive element, and an external circuit system. The micro-arc oxidation insulating layer is located on the surface of the first conductive element; The hydrophobic insulating layer is located on the surface of the micro-arc oxidation insulating layer; The second conductive element is disposed above the hydrophobic insulating layer; The external circuit system is used to connect the first conductive element and the second conductive element.

2. The micro-arc oxidation based droplet power generation device according to claim 1, wherein The first conductive element or the second conductive element is made of a material with conductive properties.

3. The micro-arc oxidation based droplet power generation device of claim 2, wherein, The first conductive element comprises one of aluminum, copper alloy, stainless steel, aluminum alloy, magnesium alloy, and titanium alloy; And / or, the second conductive element comprises one of stainless steel, aluminum, copper, aluminum alloy, magnesium alloy, and titanium alloy.

4. The micro-arc oxidation based droplet power generation device of claim 1, wherein, The preparation steps of the micro-arc oxidation insulating layer include: after pretreating the first conductive element, performing micro-arc oxidation treatment in an electrolyte to generate the micro-arc oxidation insulating layer in situ on the surface of the first conductive element.

5. The droplet power generation device based on micro-arc oxidation as described in claim 4, characterized in that, The pretreatment includes: after the first conductive element is polished, it is ultrasonically cleaned in acetone, ethanol and water for 3 minutes each, and then dried. And / or, the parameters of the micro-arc oxidation treatment include: voltage 350-480V, frequency 1000Hz, duty cycle 20%, and treatment time 5min; And / or, the electrolyte comprises 15 g / L sodium silicate and 3 g / L sodium hydroxide.

6. The droplet power generation device based on micro-arc oxidation as described in claim 1, characterized in that, The hydrophobic insulating layer is made of a hydrophobic insulating material with surface charge.

7. The droplet power generation device based on micro-arc oxidation as described in claim 6, characterized in that, The hydrophobic insulating material with surface charge includes low surface energy fluoropolymer materials.

8. The application of the droplet power generation device based on micro-arc oxidation as described in any one of claims 1-7 in the field of power generation.

9. A method for generating electricity, characterized in that, The steps of performing electrical energy conversion using the droplet power generation device based on micro-arc oxidation as described in any one of claims 1-7 include: The conductive liquid is dripped onto the surface of the hydrophobic insulating layer of the droplet power generation device based on micro-arc oxidation; The conductive liquid spreads on the surface of the hydrophobic insulating layer and comes into contact with the second conductive element, generating an electrical signal in the external circuit.

10. The power generation method as described in claim 9, characterized in that, The surface of the hydrophobic insulating layer of the droplet power generation device based on micro-arc oxidation is inclined at an angle of 10° to 80° to the horizontal plane; And / or, the parameters of the conductive liquid droplet include: flow rate 5-15 mL / min, droplet height 10-20 cm, and single droplet volume 90-100 μL; And / or, the conductive liquid includes at least one of electrolyte liquid, ionic liquid, liquid metal and nanometal solution.

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