Flexible graphene electric heating element and preparation method and application thereof

Abstract

The embodiment of the invention provides a flexible graphene electric heating element and a preparation method and application thereof. The flexible graphene electric heating element comprises a first insulating layer, a graphene heating wire, a second insulating layer and a lead-out wire. The first insulating layer, the graphene heating wire and the second insulating layer are sequentially stacked, and the lead-out wires are electrically connected with the two ends of the graphene heating wire respectively; wherein the line width of the graphene heating wire is 0.5 mm to 50 mm, and the meter resistance of the graphene heating wire is 4.5 ohm / m to 23 ohm / m; the insulation breakdown voltage of the flexible graphene electric heating element is larger than or equal to 2500V, the long-term temperature resistance range is-40 DEG C to 450 DEG C, the thermal conversion efficiency is larger than or equal to 95%, and the leakage current is smaller than or equal to 5mA. Therefore, the flexible graphene electric heating element has the advantages of being high in heat efficiency, good in flexibility, safe and reliable.

Description

Technical Field

[0001] This invention relates to the field of heating element technology, specifically to a flexible graphene heating element and a method for preparing the flexible graphene heating element. Background Technology

[0002] With the development of technology and the improvement of people's living standards, electric heating elements are being used more and more widely in various fields such as smart wearables, medical and health care, smart homes, and industrial production. Traditional electric heating elements are mostly made of materials such as metal wires and ceramics, which have problems such as low heat conversion efficiency, poor flexibility, narrow application range, and insufficient safety performance.

[0003] In related technologies, metal wire heating elements and ceramic heating elements are commonly used in different scenarios. During use, metal wire heating elements are prone to breakage when bent or twisted due to the inherent properties of the metal material, leading to equipment malfunction. Furthermore, they suffer from high heat loss, with a heat conversion efficiency typically around 60%-70%, making them unsuitable for applications with complex curved surfaces, such as heating components in smart wearable devices. While ceramic heating elements possess some high-temperature resistance, their brittle and hard texture makes them susceptible to breakage under impact or vibration, significantly limiting their application in complex environments. Additionally, ceramic heating elements have a slow thermal response and low power density, restricting their use in miniaturized and flexible devices. Summary of the Invention

[0004] In view of this, the present invention aims to provide a flexible graphene electrothermal element and its preparation method to solve the problems of low thermal conversion efficiency, poor flexibility, and insufficient safety performance of the existing flexible graphene electrothermal elements.

[0005] This invention provides a flexible graphene heating element.

[0006] This invention provides a method for preparing a flexible graphene electrothermal element.

[0007] This invention provides one application.

[0008] The flexible graphene electrothermal element of this invention includes a first insulating layer, a graphene heating wire, a second insulating layer, and lead wires.

[0009] The first insulating layer, the graphene heating wire, and the second insulating layer are stacked sequentially. The edges of the first insulating layer and the second insulating layer are bonded together by hot pressing to clamp and seal the graphene heating wire to form an integrated encapsulation structure. The lead wires are electrically connected to both ends of the graphene heating wire. The graphene heating wire has a linewidth of 0.5mm to 50mm and a resistance per meter of 4.5Ω / m to 23Ω / m; the flexible graphene heating element has an insulation breakdown voltage ≥2500V, a long-term temperature range of -40℃ to 450℃, a thermal conversion efficiency ≥95%, and a leakage current ≤5mA.

[0010] The flexible graphene heating element of this invention fully utilizes the excellent electrical and thermal properties of graphene by employing a graphene heating wire as the heating element. Graphene itself has high electrical and thermal conductivity, enabling the heating wire to quickly convert electrical energy into heat energy when energized, achieving a high-efficiency conversion efficiency of ≥95%. Furthermore, compared to traditional metal wire and ceramic heating elements, graphene is flexible, giving the heating element excellent flexibility and allowing it to adapt to various complex curved surface applications without being easily damaged by bending or twisting.

[0011] Furthermore, by limiting its high insulation breakdown voltage and low leakage current, safety is ensured, effectively preventing safety accidents caused by leakage in both home and industrial environments. Its wide long-term temperature range allows the heating element to operate stably under extreme temperature conditions without affecting performance or shortening its lifespan due to significant temperature changes.

[0012] Furthermore, the limited range of heat conversion efficiency means that electrical energy can be efficiently converted into heat energy, which greatly reduces energy loss compared to traditional electric heating elements and is in line with the current development trend of energy conservation and environmental protection.

[0013] The linewidth range of the graphene heating wire serves two purposes. Firstly, it avoids the problem of excessively narrow linewidth leading to high resistance, excessive heat concentration, and potential safety hazards. It also prevents insufficient mechanical strength due to insufficient linewidth, which could cause breakage during use. Secondly, it avoids the problem of excessively wide linewidth resulting in too low resistance, making precise power control of the heating element difficult and unable to meet the diverse power requirements of different applications. Furthermore, excessively wide linewidths would increase material costs and reduce the product's economic viability.

[0014] Furthermore, by limiting the range of the microresistance of the graphene heating wire, two advantages are achieved: First, excessively low microresistance can lead to excessive current, potentially causing the heating element to exceed its rated current during operation, resulting in overheating or even short circuits, severely impacting the element's lifespan and safety. Second, excessively high microresistance can cause low heating efficiency, preventing the element from reaching the required operating temperature within the specified time, thus reducing its efficiency and failing to meet the demands of practical applications. In addition, a suitable microresistance range ensures stable operation of the heating element under different voltage conditions, improving its adaptability to various power supply environments and enabling the flexible graphene heating element to operate reliably in a variety of complex circuit systems.

[0015] Meanwhile, the high temperature resistance allows the lead wires to operate normally within the long-term temperature range of -40℃ to 450℃ of the heating element, without problems such as wire aging or short circuits due to high temperatures, further improving the reliability and stability of the entire heating element.

[0016] Therefore, the flexible graphene electric heating element of the present invention has the advantages of high thermal efficiency, good flexibility, and safety and reliability.

[0017] In one embodiment, both the first insulating layer and the second insulating layer are polyimide films.

[0018] In some embodiments, the thickness of each of the first insulating layer and the second insulating layer is 0.05 mm to 0.2 mm.

[0019] In some embodiments, in the width direction, the width of each of the first insulating layer and the second insulating layer exceeds the width of the graphene heating wire by 2 mm to 4 mm.

[0020] In some embodiments, the edges of the integrated packaging structure are sealed, and the width of the sealed edge is 1mm to 2mm.

[0021] In some embodiments, the graphene heating wire has a linewidth tolerance of ±0.05 mm in its length extension direction and a resistance per meter deviation of no more than ±2%.

[0022] In some embodiments, the lead wire is a high-temperature resistant silver-plated wire.

[0023] In some embodiments, the diameter of the lead wire is 0.3mm to 0.5mm.

[0024] In some embodiments, the lead wire and the graphene heating wire are fixed by ultrasonic welding, and the weld joint is sealed with insulating sealant.

[0025] In some embodiments, the power density of the flexible graphene heating element is 0.46 W / cm². 2 ~88.52W / cm 2 The rated voltage is 5V~220V, the maximum operating current is 3A, and the response time is ≤0.1s.

[0026] The method for preparing the flexible graphene electrothermal element according to an embodiment of the present invention includes the following steps: Preparation of S1 graphene heating wire: The graphene heating wire is obtained by cutting graphene material; S2 Insulation Encapsulation: First, lay the first insulating layer flat on the worktable, place the graphene heating wire on the first insulating layer, and then cover it with the second insulating layer to form a laminate. The edges of the laminate are then heat-pressed and bonded to form an integrated encapsulation blank. S3 Lead-out: Remove part of the first insulation layer and / or the second insulation layer at the edge of the integrated packaging blank to expose the conductive area of ​​the graphene heating wire, weld the lead-out wire to the conductive area, and apply an insulating sealing layer to the weld.

[0027] In some embodiments, in step S1, the graphene heating wire is obtained by laser cutting; In some embodiments, in step S2, the first insulating layer and the second insulating layer undergo plasma surface treatment before hot pressing, with a treatment power of 300W~500W and a treatment time of 1min~2min, in order to improve the bonding strength.

[0028] In some embodiments, in step S2, a hot pressing device is used for hot pressing bonding, the hot pressing temperature is controlled at 180~200℃, the hot pressing pressure is 0.3MPa~0.5MPa, and the hot pressing time is 5min~30min.

[0029] In some embodiments, in step S3, a portion of the first insulating layer and / or the second insulating layer is removed at both ends of the integrated packaging blank by wire cutting.

[0030] In some embodiments, in step S3, the lead wire is connected to the conductive area by ultrasonic welding, with a welding power of 800W~1000W and a welding time of 0.5s~1s.

[0031] In some embodiments, in step S3, after welding is completed, high-temperature resistant silicone adhesive is applied to the weld, and the area is placed in a constant temperature oven for curing. The curing temperature is 120℃~150℃, and the curing time is 30min~60min. After curing, an insulating sealing layer is formed.

[0032] In some embodiments, the preparation method of the flexible graphene heating element further includes S4 molding process: the packaged product is wound or cut into shape, and wound into shape.

[0033] In some embodiments, the flexible graphene heating element of the present invention is applied in smart wearables, medical and health, smart homes or industrial fields.

[0034] In some embodiments, the flexible graphene heating element is embedded in thermal underwear, heated gloves, or knee pads, with a working power of 2W to 10W. In the medical and health field, the flexible graphene heating element is integrated into a heat therapy device or moxibustion auxiliary device, with a working temperature of 40℃ to 60℃.

[0035] In some embodiments, within the smart home field, the flexible graphene heating element is used in flexible heating pads, wall-mounted decorative panels, or desktop heaters, with a working power of 50W~200W; the flexible graphene heating element is also used for pipe heat tracing, equipment insulation, or mold preheating, with a working power density of 50W / cm³. 2 ~88.52W / cm 2 . Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of the flexible graphene electrothermal element according to an embodiment of the present invention.

[0037] Explanation of reference numerals in the attached figures: First insulating layer 1; Graphene heating wire 2; Second insulating layer 3. Detailed Implementation

[0038] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0039] The following is for reference. Figure 1 The following describes, by way of example, the flexible graphene electrothermal element and its preparation method according to embodiments of the present invention.

[0040] The flexible graphene electrothermal element of this invention includes a first insulating layer 1, a graphene heating wire 2, a second insulating layer 3, and lead wires.

[0041] The first insulating layer 1, the graphene heating wire 2, and the second insulating layer 3 are stacked sequentially. The edges of the first insulating layer 1 and the second insulating layer 3 are bonded together by hot pressing to clamp and seal the graphene heating wire to form an integrated encapsulation structure. The lead wires are electrically connected to both ends of the graphene heating wire. The graphene heating wire has a linewidth of 0.5mm to 50mm and a resistance per meter of 4.5Ω / m to 23Ω / m; the flexible graphene heating element has an insulation breakdown voltage ≥2500V, a long-term temperature range of -40℃ to 450℃, a thermal conversion efficiency ≥95%, and a leakage current ≤5mA.

[0042] The flexible graphene heating element of this invention fully utilizes the excellent electrical and thermal properties of graphene by employing a graphene heating wire as the heating element. Graphene itself has high electrical and thermal conductivity, enabling the heating wire to quickly convert electrical energy into heat energy when energized, achieving a high-efficiency conversion efficiency of ≥95%. Furthermore, compared to traditional metal wire and ceramic heating elements, graphene is flexible, giving the heating element excellent flexibility and allowing it to adapt to various complex curved surface applications without being easily damaged by bending or twisting.

[0043] Furthermore, by limiting its high insulation breakdown voltage and low leakage current, safety is ensured in use, effectively preventing safety accidents caused by leakage in both home and industrial environments. Its wide long-term temperature resistance range allows the heating element to operate stably under extreme temperature conditions without performance degradation or shortened lifespan due to significant temperature changes. After 1000 hours of high-temperature aging testing, its performance remained stable, with no burning, odor, or deformation, ensuring safe use.

[0044] Furthermore, a heat conversion efficiency of ≥95% means that electrical energy can be efficiently converted into heat energy, resulting in lower energy consumption and significant energy-saving effects. Compared with traditional electric heating elements, it greatly reduces energy loss and is in line with the current development trend of energy conservation and environmental protection.

[0045] The linewidth range of the graphene heating wire serves two purposes. Firstly, it avoids the problem of excessively narrow linewidth leading to high resistance, excessive heat concentration, and potential safety hazards. It also prevents insufficient mechanical strength due to insufficient linewidth, which could cause breakage during use. Secondly, it avoids the problem of excessively wide linewidth resulting in too low resistance, making precise power control of the heating element difficult and unable to meet the diverse power requirements of different applications. Furthermore, excessively wide linewidths would increase material costs and reduce the product's economic viability.

[0046] Furthermore, by limiting the range of the microresistance of the graphene heating wire, two advantages are achieved: First, excessively low microresistance can lead to excessive current, potentially causing the heating element to exceed its rated current during operation, resulting in overheating or even short circuits, severely impacting the element's lifespan and safety. Second, excessively high microresistance can cause low heating efficiency, preventing the element from reaching the required operating temperature within the specified time, thus reducing its efficiency and failing to meet the demands of practical applications. In addition, a suitable microresistance range ensures stable operation of the heating element under different voltage conditions, improving its adaptability to various power supply environments and enabling the flexible graphene heating element to operate reliably in a variety of complex circuit systems.

[0047] Meanwhile, the high temperature resistance allows the lead wires to operate normally within the long-term temperature range of -40℃ to 450℃ of the heating element, without problems such as wire aging or short circuits due to high temperatures, further improving the reliability and stability of the entire heating element.

[0048] Therefore, the flexible graphene electric heating element of the present invention has the advantages of high thermal efficiency, good flexibility, and safety and reliability.

[0049] Both the first insulating layer and the second insulating layer are polyimide films.

[0050] The flexible graphene heating element of this invention comprises a polyimide film in both the first and second insulating layers. The polyimide film itself possesses excellent high-temperature resistance, which is compatible with the long-term temperature range of -40℃ to 450℃ of the flexible graphene heating element. This ensures stable physical and chemical properties throughout the entire operating temperature range, preventing aging and deformation due to temperature changes, thus guaranteeing long-term stable operation. Tests show a service life exceeding 10,000 hours.

[0051] Meanwhile, the polyimide film also possesses excellent electrical insulation properties, which plays a crucial role in improving the insulation breakdown voltage of flexible graphene heating elements. It effectively prevents current leakage, ensuring that the leakage current of the element is controlled within a safe range of ≤5mA, further enhancing the safety of the element's use.

[0052] The thickness of each of the first insulating layer and the second insulating layer is 0.05mm to 0.2mm.

[0053] The flexible graphene heating element of this invention, through the thickness range of the first and second insulating layers, ensures that the insulating layers have sufficient strength and stability without compromising the overall flexibility of the element due to excessive thickness. The appropriate thickness allows the insulating layer to effectively protect the graphene heating wire from external physical damage and chemical corrosion during encapsulation, while also ensuring a tight fit with the graphene heating wire and lead wires to form a stable, integrated encapsulation structure.

[0054] Optionally, the thickness of each of the first insulating layer and the second insulating layer is 0.05 mm, 0.08 mm, 0.10 mm, 0.12 mm, 0.14 mm, 0.16 mm, 0.18 mm or 0.2 mm.

[0055] In the width direction, the width of each of the first and second insulating layers exceeds the width of the graphene heating wire by 2mm to 4mm.

[0056] The flexible graphene heating element of this invention, by limiting the width of the first and second insulating layers beyond the graphene heating wire, ensures that the graphene heating wire is completely encased within the insulating layers, preventing its edges from being exposed and avoiding safety hazards such as leakage. Simultaneously, the appropriate excess width prevents the insulating layers from becoming excessively large, thus avoiding material waste and unnecessary increases in the overall element size, ensuring the element's compactness and economy. Furthermore, this design also enhances the stability of the integrated packaging structure to a certain extent, allowing the insulating layers to better fix the graphene heating wire during thermoforming, reducing displacement and shaking during use, and improving the element's reliability and lifespan.

[0057] Optionally, in the width direction, the width of each of the first insulating layer and the second insulating layer exceeds the width of the graphene heating wire by 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, or 4 mm.

[0058] The edge of the integrated packaging structure is sealed, and the width of the sealed edge is 1mm to 2mm.

[0059] The flexible graphene heating element of this invention, by setting a suitable width for the sealing edge, further enhances the sealing performance of the encapsulation structure. Sufficient sealing width not only strengthens the sealing performance but also improves the mechanical strength and stability of the element. It also prevents external moisture, dust, and other impurities from entering the integrated encapsulation structure and corroding or damaging the graphene heating wire, thereby extending the element's lifespan. Furthermore, the suitable sealing width does not add excessive weight or size, ensuring the element's flexibility and portability.

[0060] The graphene heating wire has a linewidth tolerance of ±0.05 mm in its length extension direction and a resistance per meter deviation of no more than ±2%.

[0061] The flexible graphene heating element of this invention ensures the stability and consistency of the heating wire's performance by controlling the linewidth tolerance in the length extension direction to ±0.05 mm and the resistance per meter deviation to no more than ±2% during the manufacturing process of the graphene heating wire. This results in excellent performance in terms of heating efficiency, uniformity, and reliability. Large tolerances prevent significant performance differences between individual elements, which could affect the overall quality and stability of the product. Small linewidth tolerances allow for precise control of the heating wire's dimensions during production, ensuring consistent electrical performance. A resistance per meter deviation of no more than ±2% effectively guarantees the uniformity of heating under different operating conditions, preventing localized overheating or undercooling and improving product reliability and safety.

[0062] The lead-out wire is a high-temperature resistant silver-plated wire.

[0063] The flexible graphene heating element of this invention utilizes the excellent conductivity and high-temperature resistance of silver-plated wires by setting the lead wires as high-temperature resistant silver-plated wires. The silver plating layer has extremely low resistance, which can effectively reduce the loss of electrical energy during transmission, improve the power transmission efficiency, and ensure that the flexible graphene heating element can stably obtain electrical energy, thereby achieving efficient heating.

[0064] The diameter of the lead wire is 0.3mm to 0.5mm.

[0065] The flexible graphene electrothermal element of this invention limits the diameter range of the lead wires. On the one hand, this avoids excessively thin wires, which would lead to excessive resistance and generate too much heat during current transmission, reducing power transmission efficiency and potentially causing safety hazards such as overheating or even melting. On the other hand, excessively thick wires would increase cost and weight, while reducing flexibility and making it difficult to adapt to applications requiring bending or folding. Furthermore, a suitable wire diameter ensures good connection with other components, guaranteeing stable and reliable electrical performance of the entire electrothermal element.

[0066] The lead wire and the graphene heating wire are fixed together by ultrasonic welding, and the weld joint is sealed with insulating sealant.

[0067] The flexible graphene heating element of this invention is fixed to the graphene heating wire by ultrasonic welding of lead wires, and the weld joint is encapsulated with insulating sealant. Ultrasonic welding ensures a strong connection between the lead wire and the heating wire, guaranteeing good electrical contact performance. The encapsulation with insulating sealant further improves the insulation and waterproofing performance of the weld joint, preventing issues such as short circuits and oxidation from affecting the element's performance and lifespan. Furthermore, this encapsulation method enhances the mechanical strength of the weld joint, making the connection between the lead wire and the graphene heating wire more stable and less prone to loosening or detachment due to external pulling or vibration during use.

[0068] The power density of the flexible graphene heating element is 0.46 W / cm². 2 ~88.52W / cm 2 The rated voltage is 5V~220V, the maximum operating current is 3A, and the response time is ≤0.1s.

[0069] The flexible graphene electrothermal element of this invention, by limiting the range of power density, rated voltage, maximum operating current, and response time, can adapt to a variety of different application scenarios. The wide power density range, from 0.46 W / cm² to 88.52 W / cm², means that this electrothermal element can meet the needs of small devices with low power requirements, such as wearable devices and small electronic instruments, as well as industrial equipment or large heating systems with high power requirements.

[0070] With a rated voltage between 5V and 220V, this heating element is compatible with different power supply systems. Whether it is a common household 220V power supply or some low-voltage battery-powered systems, it can provide a stable power input, greatly expanding its application range.

[0071] The maximum operating current is 3A, which ensures that the component operates normally while also ensuring that it operates within a safe current range, avoiding damage to the component or causing safety accidents due to excessive current.

[0072] Furthermore, the response time is further limited to ≤0.1s, a characteristic that enables this flexible graphene heating element to heat up rapidly.

[0073] Therefore, the embodiments of the present invention further enhance the advantages of the electric heating element in terms of thermal efficiency, flexibility, safety and reliability.

[0074] The method for preparing the flexible graphene electrothermal element according to an embodiment of the present invention includes the following steps: Preparation of S1 graphene heating wire: The graphene heating wire is obtained by cutting graphene material; S2 Insulation Encapsulation: First, the first insulating layer is laid flat on the worktable, the graphene heating wire is placed on the first insulating layer, and then the second insulating layer is covered to form a laminate. The edges of the laminate are heat-pressed and bonded to form an integrated encapsulation blank. S3 Lead-out: Remove part of the first insulation layer and / or the second insulation layer at the edge of the integrated packaging blank to expose the conductive area of ​​the graphene heating wire, weld the lead-out wire to the conductive area, and apply an insulating sealing layer to the weld.

[0075] Therefore, the method for preparing the flexible graphene heating element described in this embodiment of the invention can efficiently produce a flexible graphene heating element with excellent performance.

[0076] In step S3, when removing part of the insulating layer at the edge of the integrated packaging blank, care must be taken to ensure precision in the operation to avoid damaging the conductive area of ​​the graphene heating wire. When welding the lead wires, the ultrasonic welding parameters must be set appropriately to ensure a strong connection and good electrical contact between the wires and the heating wire. When applying the insulating sealant, ensure that the sealant evenly covers the weld area to form good insulation and waterproofing.

[0077] In step S1, the graphene heating wire is obtained by laser cutting.

[0078] The method for fabricating the flexible graphene heating element described in this embodiment of the invention, which uses laser cutting to obtain the graphene heating wire, has many significant advantages. Laser cutting has extremely high precision, enabling precise cutting of graphene material according to preset dimensions and shapes, effectively controlling the dimensional accuracy of the heating wire, and ensuring the consistency of its electrical performance.

[0079] Meanwhile, laser cutting is fast and can complete the cutting of a large number of graphene heating wires in a short time, which greatly improves production efficiency, reduces production costs, and makes large-scale production possible.

[0080] In step S2, the first insulating layer and the second insulating layer undergo plasma surface treatment before hot pressing. The treatment power is 300W~500W and the treatment time is 1min~2min to improve the bonding strength.

[0081] The method for preparing the flexible graphene heating element according to embodiments of the present invention significantly improves the physical and chemical properties of the insulating layer surface by performing plasma surface treatment on the first and second insulating layers. Within a treatment power range of 300W to 500W and a treatment time range of 1 to 2 minutes, plasma can effectively clean contaminants and impurities from the insulating layer surface, while simultaneously increasing surface roughness and the number of active groups. This enhances the intermolecular forces between the first and second insulating layers, as well as between the insulating layers and the graphene heating wire, during hot pressing, thereby greatly improving the bonding strength.

[0082] In step S2, hot pressing equipment is used for hot pressing bonding. The hot pressing temperature is controlled at 180~200℃, the hot pressing pressure is 0.3MPa~0.5MPa, and the hot pressing time is 5min~30min.

[0083] The method for preparing the flexible graphene heating element according to this invention, through precise control of hot-pressing temperature, pressure, and time, ensures perfect bonding between the first and second insulating layers and the graphene heating wire. At a hot-pressing temperature of 180-200°C, the polyimide film achieves a suitable degree of softening, ensuring tight adhesion to the graphene heating wire without causing material performance degradation due to excessive temperature. A hot-pressing pressure of 0.3MPa-0.5MPa allows for sufficient contact between the layers in the laminate, eliminating air and forming a tight, integrated structure. A hot-pressing time within the range of 5-30 minutes further ensures the sufficiency and stability of the hot-pressing process, preventing problems such as weak adhesion due to insufficient hot-pressing time or material aging due to excessive hot-pressing time.

[0084] Partial removal of the first insulating layer and / or the second insulating layer is performed at both ends of the integrated packaging preform using wire cutting. It has the advantages of high precision and smooth cut, ensuring that the size and position of the exposed graphene heating wire conductive area are accurate, and avoiding the welding quality of the lead wire and conductive area due to the removal of too much or too little insulation layer.

[0085] In step S3, the lead wire is connected to the conductive area by ultrasonic welding. The welding power is 800W~1000W and the welding time is 0.5s~1s.

[0086] The method for fabricating the flexible graphene heating element according to this invention can achieve a high-quality connection between the lead wire and the conductive area by precisely controlling the power and time of ultrasonic welding. At a welding power of 800W~1000W and a welding time of 0.5s~1s, the energy of the ultrasonic waves can fully fuse the materials of the lead wire and the conductive area, forming a strong and stable connection. Appropriate welding power ensures sufficient energy for material bonding without damaging the graphene heating wire or the lead wire due to excessive power. Appropriate welding time ensures the sufficiency and efficiency of the welding process, avoiding weak welds due to too short a time or excessive heat effects due to too long a time, which could adversely affect the performance of the element. Simultaneously, this precisely controlled welding method ensures stable resistance at the weld joint, reduces energy loss at the weld joint, and improves the energy transmission efficiency and heating performance of the entire flexible graphene heating element. Furthermore, after welding, the appearance and performance of the weld joint can be evaluated. In step S3, after welding is completed, high-temperature resistant silicone sealant is applied to the welded area and placed in a constant temperature oven for curing. The curing temperature is 120℃~150℃ and the curing time is 30min~60min. After curing, an insulating sealing layer is formed.

[0087] The method for preparing the flexible graphene heating element according to this invention further improves the insulation and sealing performance of the weld joint by applying high-temperature resistant silicone adhesive and then curing it. The high-temperature resistant silicone adhesive has good flexibility and resistance to high and low temperatures. At a curing temperature of 120℃ to 150℃ and a curing time of 30 to 60 minutes, it can form a stable and dense insulating and sealing layer. This sealing layer effectively prevents the intrusion of external moisture, oxygen, and other impurities, avoiding oxidation, short circuits, and other problems at the weld joint, thereby extending the service life of the flexible graphene heating element.

[0088] Meanwhile, the cured insulating sealant layer also enhances the mechanical strength of the weld, making it better resistant to external pulling and vibration. In actual use, flexible graphene heating elements may be subjected to various external forces, and the insulating sealant layer can protect the weld from damage, ensuring that the connection between the lead wire and the graphene heating wire remains stable and reliable at all times.

[0089] The method for preparing the flexible graphene electrothermal element according to the embodiments of the present invention further includes S4 molding process: the packaged product is wound or cut into shape, and wound into shape.

[0090] The method for preparing the flexible graphene heating element according to this invention, through the S4 molding process, enables the packaged product to better adapt to different application scenarios. Winding molding allows the product to be wound into rolls of different lengths, such as 10m / roll to 50m / roll, facilitating storage, transportation, and use in scenarios requiring long, thin heating elements. This winding method also saves space to some extent and improves the product's flexibility.

[0091] The flexible graphene heating element of this invention is applied in smart wearables, medical and health care, smart homes or industrial fields.

[0092] Furthermore, the flexible graphene heating element is embedded in thermal underwear, heated gloves, or knee pads, with a working power of 2W~10W. In the medical and health field, the flexible graphene heating element is integrated into a hot compress therapy device or moxibustion auxiliary device, with a working temperature of 40℃~60℃.

[0093] The application of the flexible graphene heating element in this invention, within the field of smart wearables, allows for the embedding of flexible graphene heating elements in thermal underwear, heated gloves, or knee pads. Leveraging its low operating power of 2W-10W, this element provides warmth while ensuring a long battery life, meeting the needs of daily activities. Simultaneously, its excellent flexibility does not compromise comfort and ease of movement, allowing for freedom of movement even in cold weather.

[0094] In the medical and health field, flexible graphene electrothermal elements integrated into heat therapy devices or moxibustion auxiliary equipment operate at a stable temperature of 40℃-60℃. This temperature range effectively promotes blood circulation, relieves pain and muscle fatigue, and achieves good therapeutic effects. Moreover, the fast response time of this electrothermal element allows it to quickly reach the required operating temperature, saving patients waiting time and improving treatment efficiency.

[0095] In the field of smart homes, the flexible graphene heating element is used in flexible heating pads, wall-mounted decorative panels, or desktop heaters, with a working power of 50W~200W; the flexible graphene heating element is also used for pipe heat tracing, equipment insulation, or mold preheating, with a working power density of 50W / cm³. 2 ~88.52W / cm 2 .

[0096] The flexible graphene heating element of this invention, applied in the field of smart homes, can be used in flexible heating pads, wall-mounted decorative panels, or desktop heaters. With a working power of 50W-200W, it can quickly and efficiently raise indoor temperatures, creating a warm and comfortable living environment. Simultaneously, its flexibility allows these heating devices to better integrate with the home environment, without occupying excessive space, and can be flexibly installed and arranged according to actual needs. Flexible graphene heating elements used for pipe heat tracing, equipment insulation, or mold preheating, with a power of 50W / cm², are also applicable. 2 -88.52W / cm 2 Its high power density provides sufficient heat for these industrial scenarios, ensuring the flow of media in pipelines, normal operation of equipment, and proper preheating of molds, thereby improving production efficiency and product quality.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0098] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0099] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0100] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0101] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0102] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0103] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A flexible graphene electrothermal element, characterized in that, include: A first insulating layer, a graphene heating wire, and a second insulating layer are stacked in sequence. The edges of the first insulating layer and the second insulating layer are bonded together by hot pressing to clamp and seal the graphene heating wire to form an integrated encapsulation structure. Lead wires are provided, and the lead wires are electrically connected to both ends of the graphene heating wire; The graphene heating wire has a linewidth of 0.5mm to 50mm and a resistance per meter of 4.5Ω / m to 23Ω / m. The flexible graphene heating element has an insulation breakdown voltage ≥2500V, a long-term temperature range of -40℃ to 450℃, a thermal conversion efficiency ≥95%, and a leakage current ≤5mA.

2. The flexible graphene electrothermal element according to claim 1, characterized in that, Both the first insulating layer and the second insulating layer are polyimide films; And / or, the thickness of each of the first insulating layer and the second insulating layer is 0.05mm to 0.2mm; And / or, in the width direction, the width of each of the first insulating layer and the second insulating layer exceeds the width of the graphene heating wire by 2 mm to 4 mm; And / or, the edge of the integrated packaging structure has a sealing edge, the width of which is 1mm to 2mm.

3. The flexible graphene electrothermal element according to claim 1, characterized in that, The graphene heating wire has a linewidth tolerance of ±0.05 mm in its length extension direction and a resistance per meter deviation of no more than ±2%.

4. The flexible graphene electrothermal element according to claim 1, characterized in that, The lead-out wire is a high-temperature resistant silver-plated wire; And / or, the diameter of the lead wire is 0.3mm~0.5mm; And / or, the lead wire is fixed to the graphene heating wire by ultrasonic welding, and the weld joint is sealed with insulating sealant.

5. The flexible graphene electrothermal element according to claim 1, characterized in that, The power density of the flexible graphene heating element is 0.46 W / cm². 2 ~88.52W / cm 2 The rated voltage is 5V~220V, the maximum operating current is 3A, and the response time is ≤0.1s.

6. A method for preparing a flexible graphene electrothermal element as described in any one of claims 1-5, characterized in that, Includes the following steps: Preparation of S1 graphene heating wire: The graphene heating wire is obtained by cutting graphene material; S2 Insulation Encapsulation: First, lay the first insulating layer flat on the worktable, place the graphene heating wire on the first insulating layer, and then cover it with the second insulating layer to form a laminate. The edges of the laminate are then heat-pressed and bonded to form an integrated encapsulation blank. S3 Lead-out: Remove part of the first insulation layer and / or the second insulation layer at the edge of the integrated packaging blank to expose the conductive area of ​​the graphene heating wire, weld the lead-out wire to the conductive area, and apply an insulating sealing layer to the weld.

7. The method for preparing the flexible graphene electrothermal element according to claim 6, characterized in that, In step S1, the graphene heating wire is obtained by laser cutting; And / or, in step S2, the first insulating layer and the second insulating layer are subjected to plasma surface treatment before hot pressing, with a treatment power of 300W~500W and a treatment time of 1min~2min, in order to improve the bonding strength; And / or, in step S2, hot pressing equipment is used for hot pressing bonding, the hot pressing temperature is controlled at 180~200℃, the hot pressing pressure is 0.3MPa~0.5MPa, and the hot pressing time is 5min~30min; And / or, in step S3, a portion of the first insulating layer and / or the second insulating layer is removed at both ends of the integrated packaging blank by wire cutting; And / or, in step S3, the lead wire is connected to the conductive area by ultrasonic welding, with a welding power of 800W~1000W and a welding time of 0.5s~1s; And / or, in step S3, after welding is completed, apply high-temperature resistant silicone sealant to the weld and place it in a constant temperature oven for curing. The curing temperature is 120℃~150℃ and the curing time is 30min~60min. After curing, an insulating sealing layer is formed.

8. The method for preparing the flexible graphene electrothermal element according to claim 6, characterized in that, It also includes S4 molding process: the packaged product is wound or cut into shape, and then wound into shape.

9. An application of the flexible graphene electrothermal element as described in any one of claims 1-5, characterized in that, The flexible graphene electrothermal element is applied in smart wearables, medical and health care, smart homes or industrial fields.

10. The application according to claim 9, characterized in that, The flexible graphene electrothermal element is embedded in thermal underwear, heated gloves, or knee pads, with a working power of 2W~10W. In the medical and health field, the flexible graphene electrothermal element is integrated into a hot compress therapy device or moxibustion auxiliary device, with a working temperature of 40℃~60℃. And / or, in the field of smart homes, the flexible graphene heating element is used in flexible heating pads, wall-mounted decorative panels, or desktop heaters, with a working power of 50W~200W; the flexible graphene heating element is used for pipe heat tracing, equipment insulation, or mold preheating, with a working power density of 50W / cm³. 2 ~88.52W / cm 2 .

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