Energy storage type flexible electrode, preparation method thereof and electronic skin

Abstract

The invention relates to an energy storage type flexible electrode, a preparation method thereof and electronic skin. The energy storage type flexible electrode sequentially comprises a small-hole hydrophilic layer loaded with a phase change material, a large-hole hydrophobic layer loaded with the phase change material and a conductive material layer, wherein the phase change material is selected from any one of crosslinked polyethylene, polyurethane, polyethylene glycol and paraffin. The energy storage type flexible electrode provided by the invention realizes a directional perspiration function through wettability gradient and porosity gradient, and realizes an intelligent energy storage function by introducing a phase change material. The electronic skin prepared by using the energy storage type flexible electrode not only can reduce the surface temperature of the skin through perspiration, but also can absorb and store heat emitted by a human body, so that temperature rise is avoided; and the stored heat is released in a low-temperature environment to keep the human body warm, so that the wearing comfort of the electronic skin is further improved.

Description

Technical Field

[0001] The present invention belongs to the field of electrode technology, and in particular relates to an energy storage type flexible electrode, a preparation method thereof and electronic skin. Background Art

[0002] Due to its unique properties, such as thinness, lightness, good biocompatibility, excellent mechanical stability and skin conformality, electronic skin can collect important physiological signals of the human body in real time and continuously in a non-invasive and imperceptible way, providing a strong basis for health status analysis and opening up a convenient and non-invasive way for disease prediction, prevention, diagnosis and treatment.

[0003] As people pursue a comfortable and healthy life, the requirements for the wearing comfort of electronic skin that monitors the body condition in real time are getting higher and higher. Although some studies have achieved effective humidity management and thermal management through the design of electronic skin materials to improve the wearing comfort of electronic skin, the heat is radiated to the surrounding environment. When the human body needs to absorb the surrounding heat for warmth in the cold, this part of the heat cannot be effectively utilized, resulting in energy waste. Summary of the invention

[0004] The purpose of the present invention is to provide an energy storage type flexible electrode, a preparation method thereof and an electronic skin. The electronic skin prepared using the flexible electrode is not only breathable and sweat-permeable, but also has the function of intelligent energy storage.

[0005] To solve the above technical problems, the first aspect of the present invention provides an energy storage flexible electrode, which comprises in sequence: a small-pore hydrophilic layer loaded with a phase change material, a large-pore hydrophobic layer loaded with a phase change material, and a conductive material layer, wherein the phase change material is selected from any one of cross-linked polyethylene, polyurethane, polyethylene glycol, and paraffin.

[0006] Compared with the prior art, the energy storage type flexible electrode provided by the present invention realizes the directional perspiration function through the wettability gradient and the pore gradient, and realizes the intelligent energy storage function by introducing the phase change material. The energy storage type flexible electrode provided by the present invention has one layer of membrane that is hydrophilic and one layer that is hydrophobic, so it has a wettability gradient; and one layer of membrane is macroporous and one layer of membrane is microporous, so it also has a pore size gradient, water easily diffuses from the hydrophobic layer to the hydrophilic layer, and from the macroporous layer to the microporous layer. The side of the electrode close to the skin is a macroporous hydrophobic layer, and the side away from the skin is a microporous hydrophilic layer. Sweat will be transferred to the outer hydrophilic layer under the action of the strong capillary force of the hydrophilic layer, and the sweat of the hydrophilic layer will not return to the skin through the hydrophobic layer, so as to realize directional perspiration. In addition, the intelligent energy storage function is also realized by introducing the phase change material: the phase change material absorbs heat at high temperature and converts the heat into latent heat. The stored heat can be released in the form of latent heat below the phase change temperature, so that the electrode helps the skin cool down at high temperature and keeps the skin warm at low temperature.

[0007] Optionally, in the energy storage flexible electrode provided by the present invention, the material of the small pore hydrophilic layer is selected from any one of cellulose, cotton, polyvinyl pyrrolidone, polyacrylonitrile or silk, and the pore size of the small pore hydrophilic layer is 0.3 to 100 μm.

[0008] Optionally, in the energy storage flexible electrode provided by the present invention, the material of the macroporous hydrophobic layer is selected from any one of polydimethylsiloxane, polyurethane, fluorinated polyurethane, polyvinylidene fluoride, polystyrene or polymethyl methacrylate, and the pore size of the macroporous hydrophobic layer is 0.3 to 200 μm.

[0009] Optionally, in the energy storage flexible electrode provided by the present invention, the conductive material is selected from any one of metal nanomaterials, carbon materials or conductive polymers. The metal nanomaterial is selected from any one of metal nanoparticles, metal nanowires or metal nanosheets; the carbon material is selected from any one of carbon nanotubes, carbon black, graphene or Mxene materials; the conductive polymer is selected from any one of polypyrrole, polyaniline, and PEDOT:PSS materials.

[0010] In the energy storage flexible electrode provided by the present invention, the thickness of the small-pore hydrophilic layer loaded with phase change material is 30-500 μm, the thickness of the large-pore hydrophobic layer loaded with phase change material is 5-100 μm; the thickness of the conductive material layer is 100 nm-500 μm.

[0011] The second aspect of the present invention provides a method for preparing the energy storage flexible electrode described in the first aspect, comprising the following steps: S1: preparing a small pore hydrophilic layer by any one of an electrospinning method, a sacrificial template method, a phase separation method or a plasma treatment method, introducing a phase change material into the small pore hydrophilic layer to obtain a small pore hydrophilic layer loaded with a phase change material; S2 and S3, which may be in a variable order: preparing a macroporous hydrophobic layer and a conductive layer loaded with a phase change material on two sides of the small pore hydrophilic layer loaded with a phase change material, respectively; S2: on one side of the small pore hydrophilic layer loaded with a phase change material On the other side of the macroporous hydrophobic layer loaded with phase change material, a conductive material layer is prepared by magnetron sputtering, vacuum evaporation, electrostatic spraying, solution polymerization or interfacial polymerization; and an energy storage type flexible electrode is obtained, which comprises, in sequence, a small pore hydrophilic layer loaded with phase change material, a macroporous hydrophobic layer loaded with phase change material and a conductive layer.

[0012] The third aspect of the present invention provides an electronic skin, which includes the energy storage flexible electrode described in the first aspect of the present invention. When the human body is in a high temperature environment, the electronic skin provided by the present invention can not only reduce the skin surface temperature by sweating, but also absorb the heat emitted by the human body and store it to avoid temperature increase; in a low temperature environment, the electronic skin provided by the present invention can release the stored heat to keep the human body warm, further improving the wearing comfort of the electronic skin. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is the DSC curve of the energy storage flexible electrode in Example 1;

[0014] Figure 2 The directional water transport performance of the energy storage flexible electrode in Example 1, wherein Figure (a) shows that when water is dripped from the hydrophobic layer, it quickly penetrates into the hydrophilic layer; Figure (b) shows that when water is dripped from the hydrophilic layer, it does not penetrate into the hydrophobic layer;

[0015] Figure 3 This is the surface temperature variation curve of the energy storage flexible electrode in Example 1 when it is heated and cooled on a hot stage. DETAILED DESCRIPTION

[0016] In order to more clearly understand the purpose, characteristics and advantages of the present invention, the advantages of the present application are further illustrated in conjunction with specific examples and comparative examples. The materials used without indicating the manufacturer are all conventional products that can be purchased commercially. It should be understood that these examples are only used to illustrate the present application and are not intended to limit the scope of the present application.

[0017] An embodiment of the present invention provides an energy storage flexible electrode, which comprises in sequence: a small-pore hydrophilic layer loaded with a phase change material, a large-pore hydrophobic layer loaded with a phase change material, and a conductive layer, wherein the phase change material is selected from any one of cross-linked polyethylene, polyurethane, polyethylene glycol, and paraffin.

[0018] In some embodiments of the present invention, the material of the small-pore hydrophilic layer is selected from any one of cellulose, cotton, polyvinyl pyrrolidone, polyacrylonitrile or silk, and the pore size of the small-pore hydrophilic layer is 0.3-100 μm.

[0019] In some embodiments of the present invention, the material of the macroporous hydrophobic layer is selected from any one of polydimethylsiloxane, polyurethane, fluorinated polyurethane, polyvinylidene fluoride, polystyrene or polymethyl methacrylate, and the pore size of the macroporous hydrophobic layer is 0.3-200 μm.

[0020] In some embodiments of the present invention, the conductive material is selected from any one of metal nanomaterials, carbon materials or conductive polymers. The metal nanomaterial is selected from any one of metal nanoparticles, metal nanowires or metal nanosheets; the carbon material is selected from any one of carbon nanotubes, carbon black, graphene or Mxene materials; the conductive polymer is selected from any one of polypyrrole, polyaniline and PEDOT:PSS materials.

[0021] In some embodiments of the present invention, the thickness of the small-pore hydrophilic layer loaded with phase change material is 30-500 μm, the thickness of the large-pore hydrophobic layer loaded with phase change material is 5-100 μm; the thickness of the conductive material layer is 100 nm-500 μm.

[0022] An embodiment of the present invention provides a method for preparing the above-mentioned energy storage flexible electrode, comprising the following steps: S1: preparing a small pore hydrophilic layer by any one of an electrospinning method, a sacrificial template method, a phase separation method or a plasma treatment method, introducing a phase change material into the small pore hydrophilic layer to obtain a small pore hydrophilic layer loaded with a phase change material; S2 and S3, which may be in a variable order: preparing a macroporous hydrophobic layer and a conductive layer loaded with a phase change material on two sides of the small pore hydrophilic layer loaded with a phase change material, respectively; S2: on one side of the small pore hydrophilic layer loaded with a phase change material, adopting Prepare a macroporous hydrophobic layer by using either an electrospinning method or an electrostatic spraying method, introduce a phase change material into the macroporous hydrophobic layer, and obtain a macroporous hydrophobic layer loaded with a phase change material; S3: on the other side of the macroporous hydrophobic layer loaded with a phase change material, prepare a conductive material layer by using either a magnetron sputtering method, a vacuum evaporation method, an electrostatic spraying method, a solution polymerization method, or an interfacial polymerization method; obtain an energy storage type flexible electrode, which sequentially includes a small pore hydrophilic layer loaded with a phase change material, a macroporous hydrophobic layer loaded with a phase change material, and a conductive layer.

[0023] The embodiment of the present invention also provides an electronic skin, which includes the above-mentioned energy storage flexible electrode. When the human body is in a high temperature environment, the electronic skin provided by the present invention can not only reduce the skin surface temperature by sweating, but also absorb the heat emitted by the human body and store it to avoid temperature increase; in a low temperature environment, the electronic skin provided by the present invention can release the stored heat to keep the human body warm, further improving the wearing comfort of the electronic skin.

[0024] The energy storage type flexible electrode provided in the embodiment of the present invention realizes the directional perspiration function through the wettability gradient and the pore gradient, and realizes the intelligent energy storage function by introducing the phase change material. The energy storage type flexible electrode has one layer of hydrophilic membrane and one layer of hydrophobic membrane, so it has a wettability gradient; and one layer of membrane is macroporous and one layer of membrane is microporous, so it also has a pore size gradient, water easily diffuses from the hydrophobic layer to the hydrophilic layer, and from the macroporous layer to the microporous layer. The side of the electrode close to the skin is a macroporous hydrophobic layer, and the side away from the skin is a microporous hydrophilic layer. Sweat will be transferred to the outer hydrophilic layer under the action of the strong capillary force of the hydrophilic layer, and the sweat of the hydrophilic layer will not return to the skin through the hydrophobic layer, so as to realize directional perspiration. In addition, the intelligent energy storage function is also realized by introducing the phase change material: the phase change material absorbs heat at high temperature and converts the heat into latent heat. The stored heat can be released in the form of latent heat below the phase change temperature, so that the electrode helps the skin cool down at high temperature and keeps the skin warm at low temperature.

[0025] The following is an example of an energy storage flexible electrode according to one embodiment of the present invention.

[0026] Example 1

[0027] Firstly, polyurethane@cellulose acetate core-shell fibers were prepared by coaxial electrospinning, and the solid-solid phase change material polyurethane was encapsulated in cellulose acetate.

[0028] Then, conductive polypyrrole is polymerized on polyurethane@cellulose acetate fiber by interfacial polymerization: the polyurethane@cellulose acetate membrane is soaked in an aqueous solution containing ferric chloride and sodium sulfosalicylate oxidant and the solution is completely frozen in a refrigerator. A cyclohexane solution containing pyrrole monomer is poured on the frozen solid. Since cyclohexane has a low melting point, the cyclohexane solution is quickly frozen and becomes solid when poured on the frozen solid, so that the oxidant and pyrrole monomer exist in two solid phases respectively. The reaction is placed in an environment of 0-5°C to keep the cyclohexane solution still in a solid phase. During the polymerization process, the frozen ice containing ferric chloride gradually dissolves, and pyrrole reacts at the interface. The concentration of pyrrole at the interface decreases due to the consumption of the reaction, thereby forming a concentration gradient from cyclohexane to the interface, promoting its transfer to the solid-liquid interface, and further slowly generating polypyrrole, which is deposited on the surface of polyurethane@cellulose acetate core-shell fiber.

[0029] Finally, low surface energy polydimethylsiloxane was sprayed on one side of the polyurethane@cellulose acetate@polypyrrole membrane by electrostatic spraying to construct a wettability gradient and obtain an energy storage flexible electrode.

[0030] When the electrode is applied to human skin, it is not only breathable and perspiration-releasing, but also can intelligently regulate temperature. In a high-temperature environment, it can absorb heat from the surrounding environment and the human body and store it to prevent the temperature from rising. At low temperatures, the stored heat can be released to keep the human body warm. Moreover, the polypyrrole-based electrode has good electrothermal and photothermal conversion properties, and can heat and keep the human body warm by applying voltage or light at low temperatures.

[0031] The intelligent flexible electrode prepared in this embodiment is tested as follows: the phase change performance of the electrode when heated and cooled on a hot stage is tested.

[0032] 1. Phase change performance detection of intelligent flexible electrodes:

[0033] (1) Detection method: DSC test using differential scanning calorimeter at 10℃min -1 The test was carried out at a heating / cooling rate of .

[0034] (2) Test results: Figure 1 The DSC curve of the energy storage flexible electrode of this embodiment is shown. It can be seen that the curve has endothermic and exothermic peaks, indicating that the electrode can absorb heat when the temperature rises and release heat when the temperature drops, that is, it has phase change properties.

[0035] 2. Directional water delivery performance test of intelligent flexible electrodes:

[0036] (1) Detection method: 10 μL of ink was added to the hydrophobic layer and the hydrophilic layer of the electrode respectively, and the optical image of the fiber membrane and the transport process of the liquid on the membrane were recorded with a digital camera.

[0037] (2) Test results: Figure 2 The directional water transport performance of the smart flexible electrode of this embodiment is shown. As shown in Figure (a), when water is dripped from the hydrophobic layer, it quickly penetrates into the hydrophilic layer. As shown in Figure (b), when water is dripped from the hydrophilic layer, the water quickly diffuses in the hydrophilic layer and does not penetrate into the hydrophobic layer, indicating that the electrode has directional water transport performance.

[0038] 3. Phase change performance detection of intelligent flexible electrodes when heated and cooled on a hot stage:

[0039] (1) Detection method: Place the electrode on a hot plate for heating, turn off the hot plate for cooling, and use a thermocouple to test the change in electrode surface temperature during heating and cooling.

[0040] (2) Test results: Figure 3 The graph shows the surface temperature change curve of the energy storage flexible electrode when it is heated and cooled on a hot stage. According to the graph, a temperature platform appears when the electrode is heated on the hot stage, indicating that heat can be stored, and a temperature platform appears when it is cooled, indicating that heat can be released.

[0041] The above examples are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. An energy storage flexible electrode, characterized in that: Including in order: A small-pore hydrophilic layer loaded with phase change material, a large-pore hydrophobic layer loaded with phase change material and a conductive layer, wherein the phase change material is selected from any one of cross-linked polyethylene, polyurethane, polyethylene glycol and paraffin.

2. The energy storage flexible electrode according to claim 1, characterized in that: The material of the small-pore hydrophilic layer is selected from any one of cellulose, cotton, polyvinyl pyrrolidone, polyacrylonitrile or silk, and the pore size of the small-pore hydrophilic layer is 0.3-100 μm.

3. The energy storage flexible electrode according to claim 1, characterized in that: The material of the macroporous hydrophobic layer is selected from any one of polydimethylsiloxane, polyurethane, fluorinated polyurethane, polyvinylidene fluoride, polystyrene or polymethyl methacrylate, and the pore size of the macroporous hydrophobic layer is 0.3-200 μm.

4. The energy storage flexible electrode according to claim 1, characterized in that: The material of the conductive layer is selected from any one of metal nanomaterials, carbon materials or conductive polymers.

5. The energy storage flexible electrode according to claim 4, characterized in that: The metal nanomaterial is selected from any one of metal nanoparticles, metal nanowires or metal nanosheets.

6. The energy storage flexible electrode according to claim 4, characterized in that: The carbon material is selected from any one of carbon nanotubes, carbon black, graphene or Mxene materials.

7. The energy storage flexible electrode according to claim 4, characterized in that: The conductive polymer is selected from any one of polypyrrole, polyaniline and PEDOT:PSS materials.

8. The energy storage flexible electrode according to claim 1, characterized in that: The thickness of the small-pore hydrophilic layer loaded with phase change material is 30-500 μm, the thickness of the large-pore hydrophobic layer loaded with phase change material is 5-100 μm; the thickness of the conductive layer is 100 nm-500 μm.

9. The method for preparing the energy storage flexible electrode according to any one of claims 1 to 8, characterized in that: The steps include: S1: preparing a small pore hydrophilic layer by any one of an electrospinning method, a sacrificial template method, a phase separation method or a plasma treatment method, and introducing a phase change material into the small pore hydrophilic layer to obtain a small pore hydrophilic layer loaded with a phase change material; S2: preparing a macroporous hydrophobic layer on one side of the microporous hydrophilic layer loaded with phase change material by using any one of an electrospinning method and an electrostatic spraying method, and introducing the phase change material into the macroporous hydrophobic layer to obtain a macroporous hydrophobic layer loaded with phase change material; S3: preparing a conductive layer on the side of the macroporous hydrophobic layer loaded with phase change material away from the microporous hydrophilic layer loaded with phase change material by any one of magnetron sputtering, vacuum evaporation, electrostatic spraying, solution polymerization or interfacial polymerization; An energy storage type flexible electrode is obtained, which sequentially comprises a small-pore hydrophilic layer loaded with a phase change material, a large-pore hydrophobic layer loaded with a phase change material, and a conductive layer.

10. An electronic skin, characterized in that: The invention comprises the energy storage type flexible electrode as claimed in any one of claims 1 to 8.

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