Composite interface electrode and preparation method and application thereof

Abstract

The invention belongs to the technical field of flexible electrode materials, and particularly relates to a composite interface electrode and a preparation method and application thereof. According to the invention, an ionic polymer material which is the same as or compatible with a flexible substrate is adopted, so that a bonding layer is formed on the flexible substrate; and then coating the bonding layer with the electrode dispersion liquid, carrying out controllable partial dissolution on the surface of the cured bonding layer by using a dispersing agent in the electrode dispersion liquid, and forming a colloidal layer on the surface of the bonding layer in situ. And partially embedding the metal nanowire in the electrode dispersion liquid into the colloidal layer. During subsequent curing, the colloidal layer is cured again, and a firm mechanical interlocking structure is formed between the bonding layer and the metal nanowire layer. Firmly locking the upper-layer electrode on the lower-layer bonding layer and the substrate; the problem that the electrode layer is easy to peel off and fall off due to weak interface bonding is solved, and the durability and reliability of the electrode are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of flexible electrode materials technology, specifically relating to a composite interface electrode, its preparation method, and its application. Background Technology

[0002] Ion flexible actuators, as a novel type of smart material, possess unique properties such as high sensitivity, good flexibility, and biocompatibility, demonstrating great application potential in fields such as flexible electronics, biomedical assistive devices, and soft robotics. The performance of these actuators largely depends on the quality of the interfacial bonding between their electrodes and the ion-polymer matrix.

[0003] Currently, the adhesion between commonly used electrode layers (such as metal nanowire layers) and ionomer substrates (such as Nafion films) mainly relies on relatively weak physical interactions such as van der Waals forces. This weak interfacial bonding can easily lead to the electrode layer peeling, cracking, or detachment during use, resulting in problems such as driver performance degradation, reduced output force, and shortened lifespan.

[0004] To enhance adhesion, existing technologies employ methods such as surface modification, polymer encapsulation, and photonic sintering. However, most of these methods fail to fundamentally alter the interfacial bonding mechanism, offering limited adhesion enhancement and introducing problems such as complex processes, high costs, or damage to substrate properties. Summary of the Invention

[0005] To address the technical problem of insufficient adhesion between flexible electrodes and substrates in existing modification methods, this invention provides a composite interface electrode with strong adhesion, stable structure, and simple preparation, as well as its preparation method and applications.

[0006] This invention employs an ionomer material that is the same as or compatible with the flexible substrate to form an adhesive layer on the flexible substrate, creating a strong bond with the substrate that matches its chemical and physical properties. An electrode dispersion is then coated onto the adhesive layer, and the dispersant in the electrode dispersion controllably dissolves part of the adhesive layer surface, forming a gel-like layer in situ on the adhesive layer surface. This allows the metal nanowires in the electrode dispersion to be partially embedded within this gel-like layer. During subsequent curing, the gel-like layer re-cures, forming a strong mechanical interlocking structure between the adhesive layer and the metal nanowire layer. This structure fundamentally enhances the bonding force between the electrode layer and the substrate, achieving a stronger adhesion between the substrate and the flexible electrode, and the preparation method is simple.

[0007] The first objective of this invention is to provide a method for preparing a composite interface electrode, comprising the following steps: Metal oxide nanowires, ionomer solutions, and solvents are mixed uniformly to obtain a mixed solution. The mixed solution is coated onto a flexible substrate, and after curing, an adhesive layer is formed on the surface of the flexible substrate. Metal nanowires are dispersed in a dispersant to obtain an electrode dispersion. The electrode dispersion is coated onto the adhesive layer. The dispersant partially dissolves the surface of the adhesive layer to form a gel-like layer, allowing the metal nanowires to be partially embedded in the gel-like layer. After curing, an embedded layer is formed, consisting of metal nanowires and the surface of the adhesive layer interlocking. A metal plating layer is deposited on the surface of the embedded layer to obtain a composite interface electrode. The ionomer in the adhesive layer is the same as or compatible with the flexible substrate.

[0008] Preferably, the flexible substrate is a perfluorosulfonic acid resin film; the ionomer is a perfluorosulfonic acid resin. Using the same or compatible ionomer materials is beneficial for forming a strong bond between the adhesive layer and the flexible substrate with matching chemical and physical properties.

[0009] Preferably, the mixed solution is applied by spraying, and the application amount of the mixed solution is 0.2 mL / cm². 2 ~0.25mL / cm 2 The electrode dispersion was coated by spraying, with a coating amount of 1.0 mL / cm². 2 ~1.2mL / cm 2 .

[0010] Preferably, the ratio of metal nanowires to dispersant is 2 mg to 3 mg: 5 mL; the mass ratio of metal oxide nanowires, ionomer, and solvent is 0.02: 4 to 6: 50. This ensures that the adhesive layer has appropriate surface properties and mechanical strength, which is conducive to the formation of an effective interlocking structure.

[0011] Preferably, the metal oxide nanowires are one of manganese dioxide nanowires, iron oxide nanowires, and cobalt tetroxide nanowires. Manganese dioxide nanowires have high theoretical specific capacitance and can undergo redox cycles in alkaline environments, thereby better adsorbing working ions, increasing the pseudocapacitance of the electrode, and enhancing the charge storage of the conductive network system. More preferably, the metal oxide nanowires are manganese dioxide nanowires.

[0012] Preferably, the solvent is dimethylacetamide. Dimethylacetamide has a low boiling point and evaporates at 120°C, leaving only the metal oxide nanowires and ionomers solidified on the flexible substrate to form an adhesive layer. Preferably, the curing temperature of the adhesive layer is 120°C to 130°C.

[0013] Preferably, the metal nanowires are silver nanowires or copper nanowires.

[0014] Preferably, the curing temperature of the embedded layer is 80℃~90℃; the dispersant is ethanol. Ethanol can moderately swell or partially dissolve the surface of the Nafion-type adhesive layer to form an ideal gel-like layer without destroying the overall structure.

[0015] Preferably, a pretreatment is required before coating the flexible substrate surface. The pretreatment includes sandblasting, surface cleaning, and proton exchange. The pretreatment enhances the adhesion of the interfacial electrode to the substrate, while also improving the chemical stability and mechanical properties of the substrate.

[0016] Preferably, the coating method is selected from one of spraying, vacuum filtration, hot pressing, and spin coating. Spray gun coating is faster and more convenient than traditional methods such as vacuum filtration, hot pressing, and spin coating, and it is also beneficial to increase the adhesion between the electrode layer and the substrate. More preferably, the coating method is spraying.

[0017] Preferably, the nozzle orifice diameter is 0.3 mm and the pressure is 0.15 MPa during spraying. Excessive or insufficient nozzle orifice diameter and pressure during spraying can lead to inconsistent thicknesses at different locations in the adhesive and embedded layers, as well as uneven distribution of the surface electrode material.

[0018] A second objective of this invention is to provide a composite interface electrode prepared by the above-described method. This electrode comprises a binder layer, an embedding layer, and a metal plating layer stacked sequentially, wherein the metal nanowires in the embedding layer are partially embedded within the surface layer of the binder layer, forming a mechanically interlocking structure.

[0019] A third objective of this invention is to provide the application of the aforementioned composite interface electrode as an electrode in an ion flexible actuator.

[0020] Compared with the prior art, the present invention has the following beneficial effects: This invention employs an ionomer material that is the same as or compatible with the flexible substrate to form an adhesive layer on the flexible substrate, creating a strong bond with the substrate through chemical and physical matching. An electrode dispersion is then coated onto the adhesive layer, and the dispersant in the electrode dispersion controllably dissolves part of the cured adhesive layer surface, thereby forming a gel-like layer in situ on the adhesive layer surface. Metal nanowires from the electrode dispersion are partially embedded within this gel-like layer. During subsequent curing, the gel-like layer re-cures, forming a strong mechanical interlocking structure between the adhesive layer and the metal nanowire layer. This firmly locks the upper electrode onto the lower adhesive layer and the substrate, solving the problem of easy peeling and detachment of the electrode layer due to weak interfacial bonding, and significantly improving the durability and reliability of the electrode.

[0021] The metal oxide nanowires selected in this invention possess pseudocapacitive properties in the adhesive layer, which can increase the charge storage capacity of the electrodes. The composite conductive network formed by the nanowires and the metal oxide nanowires enhances charge transport efficiency, thereby improving the driving capability and response speed of the ion flexible actuator.

[0022] This invention forms a dense protective shell on the embedded layer. The outermost dense metal plating not only provides good surface conductivity, but also provides effective physical protection for the internal embedded layer and adhesive layer, preventing them from being oxidized or mechanically damaged under complex working conditions, thus ensuring the stability of the electrode during long-term operation.

[0023] This invention mainly adopts conventional processes such as spraying and curing. The steps are simple, the conditions are mild, and no complex and expensive equipment is required. It is easy to achieve large-scale preparation and has good prospects for industrial application. Attached Figure Description

[0024] Figure 1 SEM planar image of the composite interface electrode prepared for the example.

[0025] Figure 2 This is a SEM cross-sectional image of the composite interface electrode prepared in Example 1.

[0026] Figure 3 The image shows a cross-sectional SEM image of the embedded layer of the composite interface electrode prepared in Example 1.

[0027] Figure 4 The displacement response curve of the composite interface electrode prepared in Example 1.

[0028] Figure 5 The displacement response curve of the composite interface electrode prepared for Comparative Example 1.

[0029] Figure 6 The displacement response curves of the composite interface electrode prepared in Example 1 under different voltages and frequencies.

[0030] Figure 7 The displacement response curve of the composite interface electrode prepared in Example 1 at an excitation frequency of 0.1 Hz. Detailed Implementation

[0031] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings.

[0032] Unless otherwise specified, all reagents used in this invention are commercially available, and all methods used are conventional techniques in the art.

[0033] It should be noted that before coating the flexible substrate surface, the substrate undergoes pretreatment, including sandblasting, surface cleaning, and proton exchange. This pretreatment enhances the adhesion of the interfacial electrode to the flexible substrate, while also improving the chemical stability and mechanical properties of the flexible substrate. Specifically, the ion exchange involves immersing the surface-cleaned substrate in a 0.6 mol / L NaOH solution for 2–4 hours. During ion exchange, hydrogen ions in the substrate are replaced by sodium ions, making sodium ions the working ions for the actuator. Simultaneously, sodium ion exchange improves the chemical stability of the substrate, resulting in better performance in the electrochemical environment. Sodium ion exchange treatment improves the adhesion between the substrate and the electrode layer. This is because the treated substrate surface carries a negative charge, enabling stronger interactions with the metal nanowires in the electrode layer, thus enhancing adhesion. Sodium ion exchange contributes to the formation of a more stable polymer-metal interface, which is crucial for improving the electrochemical performance and mechanical stability of the IPMC actuator.

[0034] The pretreatment method for the matrix used in the following embodiments is as follows: A 6cm x 6cm piece of Nafion 117 film was cut out. After fixing the Nafion 117 film with the device, it was sandblasted using 120# white corundum abrasive. The sandblasting pressure was 0.4MPa, the vertical distance between the spray gun and the Nafion 117 film was 15cm, and each side of the Nafion 117 film was sanded for 60 seconds. During the sandblasting process, the sandblasting machine moved in a zigzag motion at a constant speed. After sanding, the Nafion 117 film was cut into pieces with dimensions of 3cm x 1.5cm.

[0035] A 3cm × 1.5cm Nafion 117 membrane was placed in ethanol and ultrasonically cleaned for 40 min. Then, it was placed in 200 mL of 2 mol / L hydrochloric acid solution, heated to 100℃, and boiled for 30 min. Next, the hydrochloric acid-washed Nafion 117 membrane was placed in 200 mL of 15% H2O2 solution, heated to 100℃, and boiled for 30 min. Finally, the H2O2-washed Nafion 117 membrane was placed in 200 mL of boiling water and boiled for 30 min.

[0036] The Nafion117 membrane, after being boiled in water, was immersed in a 0.6 mol / L NaOH solution for 2 hours for ion exchange to obtain a pretreated Nafion117 membrane.

[0037] Example 1 A method for preparing a composite interface electrode includes the following steps: Step 1: Prepare the adhesive layer: Weigh 0.04 g of manganese dioxide nanowires, 10 g of Nafion solution (perfluorosulfonic acid polymer solution, 20%, Shanghai Hesen Electric Co., Ltd.) and 100 g of dimethylacetamide and mix them. Stir magnetically at room temperature for 2 h to completely disperse the manganese dioxide nanowires and Nafion solution in the dimethylacetamide to obtain a mixed solution.

[0038] The pretreated Nafion 117 film was placed flat on a glass plate, and clamped on both sides with a fixture, leaving a 2.5cm × 1.5cm spraying area for the substrate film. The spray gun pressure was then set to 0.15MPa, and the mixed solution was evenly sprayed onto the Nafion 117 film using a spray gun with a nozzle orifice diameter of 0.3mm. The spraying volume of the mixed solution was approximately 0.213mL / cm². 2 After spraying, it is dried and cured on a heating platform at 120℃ to form an adhesive layer.

[0039] Step 2: Prepare the embedding layer: 40 mg of silver nanowires and 100 mL of anhydrous ethanol were weighed into a beaker and magnetically stirred at room temperature for 2 h to obtain an electrode dispersion. The spray gun pressure was set to 0.15 MPa and the nozzle orifice diameter to 0.3 mm, and the electrode dispersion was uniformly sprayed onto the adhesive layer; the spraying amount of electrode dispersion was approximately 1.067 mL / cm². 2 During the spraying process, ethanol partially dissolves the surface of the adhesive layer, forming a gel-like layer in which silver nanowires are partially embedded under gravity. Subsequently, it is dried and cured at a heating platform of 80°C to form an embedded layer.

[0040] Step 3: Fabrication of composite interface electrode: The intercalation layer is electroplated with a gold ion solution to reduce gold ions to gold atoms, which are then deposited onto the intercalation layer to form an electroplated layer, thus obtaining a composite interface electrode.

[0041] Comparative Example 1 The difference from Example 1 is as follows: When preparing the adhesive layer, no manganese dioxide nanowires were added; instead, 10g of Nafion solution was mixed with 100g of dimethylacetamide and then sprayed and cured.

[0042] A method for preparing a composite interface electrode includes the following steps: Step 1: Prepare the adhesive layer: Weigh 10g of Nafion solution and 100g of dimethylacetamide and mix them. Stir magnetically at room temperature for 2 hours to completely disperse the Nafion solution in the dimethylacetamide, thus obtaining a mixed solution.

[0043] The pretreated Nafion 117 film was placed flat on a glass plate, and clamped on both sides with a fixture, leaving a 2.5cm × 1.5cm spraying area for the substrate film. The spray gun pressure was then set to 0.15MPa, and the mixed solution was evenly sprayed onto the Nafion 117 film using a spray gun with a nozzle orifice diameter of 0.3mm. The spraying volume of the mixed solution was 0.213mL / cm². 2 After spraying, it is dried and cured on a heating platform at 120℃ to form an adhesive layer.

[0044] Step 2: Prepare the embedding layer: 40 mg of silver nanowires and 100 mL of anhydrous ethanol were weighed into a beaker and magnetically stirred at room temperature for 2 h to obtain an electrode dispersion. The spray gun pressure was set to 0.15 MPa and the nozzle orifice diameter to 0.3 mm, and the electrode dispersion was uniformly sprayed onto the adhesive layer; the spraying rate of the electrode dispersion was 1.067 mL / cm². 2 During the spraying process, ethanol partially dissolves the surface of the adhesive layer, forming a gel-like layer in which silver nanowires are partially embedded under gravity. Subsequently, it is dried and cured at a heating platform of 80°C to form an embedded layer.

[0045] Step 3: Fabrication of composite interface electrode: The intercalation layer is electroplated with a gold ion solution to reduce gold ions to gold atoms, which are then deposited onto the intercalation layer to form an electroplated layer, thus obtaining a composite interface electrode.

[0046] Test 1.

[0047] from Figure 1 and Figure 2 It is evident that the composite interface electrode prepared in Example 1 has a uniform and dense surface, with a clearly visible cross-sectional structure, exhibiting a good layered structure. The electroplated gold protective layer is densely adhered to the surface of the adhesive layer, effectively protecting the internal conductive network.

[0048] Depend on Figure 1 , Figure 2 and Figure 3 It can be seen that the embodiments of the present invention successfully prepared a gold composite interface electrode, indicating that the present invention can prepare a composite interface electrode composed of an adhesive layer, an embedded layer and an electroplated layer on a substrate film; and verify the formation of a mechanical interlocking structure.

[0049] Test 2.

[0050] The driving performance of the composite interface electrodes prepared in Example 1 and Comparative Example 1 was tested under a 2V square wave voltage and a 0.1Hz frequency excitation: from Figure 4It can be seen that the actuator can quickly generate a significant bending displacement after voltage application, and the displacement change is stable and repeatable within a complete cycle, without significant attenuation or fluctuation. This result indicates that the composite interface electrode prepared in Example 1 of this invention can effectively drive the ion flexible actuator under low voltage conditions. Its good interface bonding and continuous conductive network facilitate the rapid migration and redistribution of working ions, thereby improving the driving response efficiency.

[0051] from Figure 5 It can be seen that the sample of Comparative Example 1 can also produce a certain degree of bending displacement under the applied voltage, but its displacement amplitude is significantly lower than that of the sample of Example 1, and the stability of the displacement response is poor. Furthermore, during multiple consecutive driving cycles, the displacement peak of the comparative example sample fluctuates, and the displacement response weakens in some cycles, indicating insufficient consistency and repeatability of its driving output. This is mainly because the adhesive layer of the comparative example sample does not incorporate metal oxide nanowires, and the interfacial bonding between the electrode layer and the substrate mainly relies on physical adsorption. The interfacial bonding strength is limited, making it prone to micro-slippage or local relaxation during repeated electro-deformation. In addition, under the same driving voltage conditions, the sample of Comparative Example 1 struggles to maintain a large stable displacement output, indicating that its interfacial structure has limited support for ion migration and charge transport under the influence of an electric field, thus limiting further improvement in driving performance.

[0052] The comparative sample, lacking the composite adhesive layer and mechanical interlocking structure constructed in Example 1, exhibited limitations in both driving displacement amplitude and stability. This comparative result further verifies that the present invention, by introducing metal oxide nanowires and constructing an embedded composite interface structure, has significant advantages in improving the driving performance and operational stability of ion flexible actuators.

[0053] The driving performance of the composite interface electrode prepared in Example 1 was tested under different voltages and frequencies: from Figure 6 It can be seen that the output displacement of the sample gradually increases with the increase of the driving voltage, indicating a good response relationship between the driving performance and the applied electric field strength. This shows that the composite interface electrode can maintain stable electrochemical and mechanical properties under different operating voltages. Furthermore, the actuator can still maintain a identifiable displacement response under different excitation frequencies, indicating that the constructed composite interface electrode helps to reduce interfacial impedance, improve ion migration rate, and enable the actuator to have good operating stability within a certain frequency range.

[0054] Under an excitation frequency of 0.1 Hz, square wave driving voltages of 1 V and 2 V were applied to the sample of Example 1, and the changes in its end displacement over time are as follows: like Figure 7As shown, under a 1V driving voltage, the sample of Example 1 exhibits a stable and periodic bending displacement response. The displacement change shows good synchronicity with voltage loading and unloading, and the displacement amplitude remains essentially consistent across multiple driving cycles without significant attenuation, indicating good stability and repeatability of the driving process. When the driving voltage is increased to 2V, the end displacement amplitude of the sample of Example 1 increases significantly, with its maximum displacement being significantly higher than that under the 1V condition, while the displacement response still maintains a regular periodic variation. This indicates that under the same frequency conditions, the driving displacement increases with increasing applied voltage, demonstrating good voltage response characteristics.

[0055] The above results demonstrate that the composite interface electrode prepared in this embodiment of the invention can maintain stable driving behavior under different driving voltages. Increasing the voltage effectively enhances the driving output, while the excellent interfacial bonding structure of the composite interface electrode ensures that the electrode layer does not peel off or fail under a high electric field, thereby achieving stable and controllable driving performance.

[0056] It should be noted that when numerical ranges are involved in this invention, it should be understood that the two endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described in this invention to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments, and all such changes and modifications fall within the scope of this invention.

[0057] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If these modifications and variations fall within the scope of equivalents of this invention, then this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a composite interface electrode, characterized in that, Includes the following steps: Metal oxide nanowires, ion polymer solution and solvent are mixed evenly to obtain a mixed solution; The mixed solution is coated onto a flexible substrate, and after curing, an adhesive layer is formed on the surface of the flexible substrate; Metal nanowires are dispersed in a dispersant to obtain an electrode dispersion; The electrode dispersion is coated onto the adhesive layer; wherein, the dispersant partially dissolves the surface of the adhesive layer to form a gel layer, and the metal nanowires are partially embedded in the gel layer; after curing, an embedded layer is formed by the interlocking of the metal nanowires and the surface of the adhesive layer. A metal coating is deposited on the surface of the embedded layer to obtain a composite interface electrode; The ionomer in the adhesive layer is the same as or compatible with the flexible matrix.

2. The method for preparing the composite interface electrode according to claim 1, characterized in that, The flexible substrate is a perfluorosulfonic acid resin membrane; the ionomer is a perfluorosulfonic acid resin.

3. The method for preparing the composite interface electrode according to claim 1, characterized in that, The coating amount of the mixed solution was 0.2 mL / cm². 2 ~0.25mL / cm 2 ; The coating amount of the electrode dispersion was 1.0 mL / cm². 2 ~1.2mL / cm 2 .

4. The method for preparing the composite interface electrode according to claim 1, characterized in that, The ratio of metal nanowires to dispersant is 2 mg to 3 mg: 5 mL; The mass ratio of metal oxide nanowires, ionomers, and solvents is 0.02:4 to 6:

50.

5. The method for preparing the composite interface electrode according to claim 1, characterized in that, The metal oxide nanowires are one of manganese dioxide nanowires, iron oxide nanowires, and cobalt tetroxide nanowires; the metal nanowires are silver nanowires or copper nanowires.

6. The method for preparing the composite interface electrode according to claim 1, characterized in that, The curing temperature of the adhesive layer is 120℃~130℃; the solvent is dimethylacetamide.

7. The method for preparing the composite interface electrode according to claim 1, characterized in that, The curing temperature of the embedded layer is 80℃~90℃; the dispersant is ethanol.

8. A composite interface electrode, characterized in that, The composite interface electrode is prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the composite interface electrode of claim 8 as an electrode in an ion flexible actuator.

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