Method for synergistically modifying electrical conductivity and mechanical properties of integrated electrodes and applications

Abstract

This application belongs to the field of materials technology and provides a method and application for synergistic modification of the conductivity and mechanical properties of an integrated electrode. The method includes: coating a composite modifying liquid onto the surface of a pretreated electrode substrate using a spraying method; drying the electrode after coating at 100-120°C; then, under a protective atmosphere with a flow rate of 100-400 mL / min, first heating to 200-250°C at a heating rate of 3-10°C / min and holding at that temperature; then heating to 300-350°C at a heating rate of 3-10°C / min and holding at that temperature; finally, cooling and drying to obtain the integrated electrode. This method for synergistic modification of the conductivity and mechanical properties of an integrated electrode enables simultaneous improvement in the conductivity, mechanical properties, and structural stability of the integrated electrode, meeting the industrialization requirements of electrochemical devices.

Description

Technical Field

[0001] This application belongs to the field of materials technology, and in particular relates to a method and application for synergistic modification of the conductivity and mechanical properties of an integrated electrode. Background Technology

[0002] With the development of science and technology, electrochemical devices such as lithium-ion batteries, supercapacitors, and fuel cells have been widely researched and applied in fields such as new energy vehicles, large-scale energy storage, and portable electronic devices. Among them, integrated electrodes are well-suited for these electrochemical devices due to their advantages such as compact structure, low interfacial contact resistance, high energy density, and short ion transport path.

[0003] Currently, integrated electrodes face numerous bottlenecks during long-term service. To address these bottlenecks, various modification methods have been proposed, but most only optimize conductivity or mechanical properties. This results in complex preparation processes, limited modification effects, poor environmental friendliness, and problems such as the mutual constraint between conductivity and mechanical properties, weak interfacial bonding, and short service life of the resulting integrated electrodes. Consequently, these methods struggle to meet the requirements of high-performance electrochemical devices.

[0004] Therefore, there is an urgent need to provide a novel method for modifying an integrated electrode, as well as the resulting integrated electrode, to solve the above problems. Summary of the Invention

[0005] In view of this, embodiments of this application provide a method and application for synergistic modification of the conductivity and mechanical properties of an integrated electrode, in order to improve the existing integrated electrode modification methods and the problems that the conductivity, mechanical properties and structural stability of the resulting integrated electrodes cannot be synergistically improved.

[0006] The first aspect of this application provides a method for synergistic modification of the conductivity and mechanical properties of an integrated electrode, comprising the following steps: An electrode substrate is selected, and after cleaning and drying, the surface of the electrode substrate is treated with plasma to obtain a pretreated electrode substrate. A composite modified liquid is obtained by first dissolving the dispersant and the silane coupling agent in the mixed solvent, then adding the graphene, the carbon nanotubes and the reinforcing phase, and shearing and dispersing them at a high speed of 10000-15000 r / min for a period of time, and finally adding the conductive polymer and the binder and mixing them. The composite modified liquid is coated onto the surface of the pretreated electrode substrate using a spraying method. The electrode coated with the composite modified liquid is then dried at a temperature of 100-120°C to allow the mixed solvent to evaporate and the binder to crosslink. A staged heat treatment is then performed under a protective atmosphere with a flow rate of 100-400 mL / min: first, the temperature is increased to 200-250°C at a rate of 3-10°C / min and held for a period of time; then, the temperature is increased to 300-350°C at a rate of 3-10°C / min and held for a period of time. After cooling and drying, the integrated electrode is obtained.

[0007] In some embodiments, selecting an electrode substrate, cleaning and drying the electrode substrate, and then activating the surface of the electrode substrate with plasma to obtain a pretreated electrode substrate includes: After selecting the electrode substrate, the electrode substrate is first ultrasonically cleaned with anhydrous ethanol for 10-20 minutes, then rinsed with deionized water 3-5 times, and dried in a vacuum drying oven at 60-80℃ for 2-4 hours. Then it is placed in a plasma treatment instrument, with protective gas as the working gas, and activated at 50-100W power for 5-15 minutes to obtain the pretreated electrode substrate.

[0008] In some embodiments, the electrode substrate is a carbon-based porous substrate, and the electrode substrate includes any one of carbon felt, carbon cloth, and carbon paper; The porosity of the electrode substrate is 50-85%; And / or, the areal density of the electrode substrate is 80-300 g / m³. 2 ; And / or, the initial volume resistivity of the electrode substrate is less than or equal to 5 × 10⁻⁶. -3 Ω•cm; And / or, the initial tensile strength of the electrode substrate is greater than or equal to 50 MPa; And / or, the surface of the electrode substrate is treated with the plasma to form a micro / nano rough structure, the roughness of which is 0.5-2.0 μm, the micro / nano rough structure comprising micrometer-scale and nanometer-scale structures, the size of which is 0.1-100 μm and the size of which is 1-100 nm, and active functional groups are introduced, the density of which is greater than or equal to 1.5 × 10⁻⁶. 15 pcs / cm 2 .

[0009] In some embodiments, the composite modified liquid comprises, by mass parts: Graphene, 5-10 parts; Carbon nanotubes, 3-6 parts; Conductive polymer, 2-5 parts; Dispersant, 1-3 parts; Adhesive, 2-4 parts; Reinforcing phase, 0.5-2 parts; Silane coupling agent, 0.3-1 part; Mixed solvent, 80-100 parts.

[0010] In some embodiments, the graphene sheet diameter is 1-5 μm; And / or, the graphene includes reduced graphene oxide; And / or, the aspect ratio of the carbon nanotubes is 100-500; And / or, the Raman spectrum of the carbon nanotubes I D / I G The ratio is 0.5-1.2; And / or, the surface carboxyl group content of the carbon nanotubes is greater than or equal to 1.0 mmol / g; And / or, the length of the carbon nanotubes is 5-50 μm; And / or, the carbon nanotubes include at least one of carboxylated multi-walled carbon nanotubes and carboxylated single-walled carbon nanotubes; The mass ratio of graphene to carbon nanotubes is 2:1 to 3:1.

[0011] In some embodiments, the conductive polymer includes at least one of polyaniline, polythiophene, and polypyrrole; And / or, the dispersant includes at least one of sodium dodecylbenzenesulfonate and polyethylene glycol; And / or, the adhesive includes at least one of polyvinylidene fluoride, sodium carboxymethyl cellulose, and styrene-butadiene rubber; And / or, the average particle size of the reinforcing phase is 50-200 nm; the reinforcing phase includes at least one of the following: a composite of nano-alumina and chopped carbon fibers, nano-silica, and a core-shell structure composed of carbon-coated alumina; And / or, in the nano-alumina and chopped carbon fiber composite, the mass ratio of nano-alumina to chopped carbon fiber is 1:1, the nano-alumina is spherical in shape, and the purity of the nano-alumina is greater than or equal to 99.5%; the average length of the chopped carbon fiber is 50-200 μm, the diameter of the chopped carbon fiber is 5-15 μm, the carboxyl content on the surface of the chopped carbon fiber after oxidation treatment is greater than or equal to 0.8 mmol / g, and the aspect ratio of the chopped carbon fiber is 30-40; And / or, the mass ratio of the reinforcing phase to the silane coupling agent is 1:0.3-1:0.8; And / or, the mixed solvent comprises water and N-methylpyrrolidone, wherein the volume ratio of water to N-methylpyrrolidone is 1:1 to 1:3.

[0012] In some embodiments, the spraying pressure in the spraying method is 0.2-0.4 MPa, and the spraying distance in the spraying method is 10-15 cm.

[0013] In some embodiments, the step of performing staged heat treatment under a protective atmosphere with a flow rate of 100-400 mL / min includes: first heating to 200-250°C at a heating rate of 3-10°C / min and holding at that temperature for a period of time, and then heating to 300-350°C at a heating rate of 3-10°C / min and holding at that temperature for a period of time. Then, a staged heat treatment is carried out under an inert gas atmosphere with a flow rate of 100-400 mL / min: first, the temperature is raised to 200-250℃ at a heating rate of 3-10℃ / min and held for 1-4 hours; then, the temperature is raised to 300-350℃ at a heating rate of 3-10℃ / min and held for 30-60 minutes.

[0014] A second aspect of this application provides an integrated electrode prepared by the method described above for synergistic modification of the conductivity and mechanical properties of an integrated electrode. The integrated electrode includes an electrode substrate and a composite modification layer. The electrode substrate has a porous structure, and the composite modification layer has a network structure. The network structure includes a conductive network formed by the interweaving of graphene and carbon nanotubes, a reinforcing phase embedded in the pores of the conductive network, and a silane coupling agent bridging the components to the electrode substrate. The network structure is combined with the porous structure.

[0015] In some embodiments, the thickness of the composite modified layer is 1-5 μm; And / or, the porosity of the conductive network is 30-60%; And / or, the interlacing density of the conductive network is 10-30 strands / μm. 2 ; And / or, the porosity of the conductive network is 30-60%; And / or, the peel strength between the composite modified layer and the electrode substrate is greater than or equal to 1.5 N / mm; And / or, the conductivity attenuation rate of the integrated electrode after 1000 bending cycles is less than or equal to 3%; And / or, the integrated electrode retains a capacity of 94% or more after 500 charge-discharge cycles.

[0016] Compared with the prior art, this application has the following technical effects: This application provides a method and application for synergistic modification of the conductivity and mechanical properties of an integrated electrode. Through modification steps such as interface activation, structural synergy, and stepwise curing, the conductivity and mechanical properties of the integrated electrode are simultaneously modified and optimized, resulting in strong interfacial bonding and long service life in the integrated electrode, ensuring excellent overall performance. Moreover, this process is environmentally friendly and suitable for large-scale production and application. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments or related technologies of this application will be briefly introduced below. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0018] Figure 1 This is a process flow diagram of a method for synergistic modification of the conductivity and mechanical properties of an integrated electrode provided in an embodiment of this application; Figure 2 This is a scanning electron microscope image of an integrated electrode provided in an embodiment of this application. Detailed Implementation

[0019] To make the technical problems to be solved, the technical solutions, and the beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0020] In this application, the term "and / or" is used to describe the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can be represented as: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the related objects before and after it have an "or" relationship.

[0021] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can be expressed as: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0022] It should be understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0023] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0024] The weights of the relevant components mentioned in the description of the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the description of the embodiments of this application is within the scope disclosed in the description of the embodiments of this application. Specifically, the mass in the description of the embodiments of this application can be a known unit of mass such as µg, mg, g, or kg.

[0025] The terms "first," "second," etc., are used merely for descriptive purposes, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature.

[0026] With the rapid development of electrochemical energy storage and conversion technologies, electrochemical devices such as lithium-ion batteries, supercapacitors, and fuel cells have been widely researched and applied in fields such as new energy vehicles, large-scale energy storage, and portable electronic devices. As the core component of these electrochemical devices, the structural design and performance of electrodes determine the energy density, power density, cycle stability, and lifespan of the electrochemical device.

[0027] In recent years, integrated electrodes have gradually become a research hotspot due to their advantages such as compact structure, strong integrity, low interfacial contact resistance, high energy density, and short ion transport paths. An integrated electrode is an electrode in which the multi-layered structure and / or multiple components that would otherwise be manufactured and assembled separately are directly integrated into a single, non-layered, non-bonded, and non-reassembled unit. After years of research and application, it has been found that integrated electrodes are well-suited for various electrochemical devices such as lithium-ion batteries, supercapacitors, and fuel cells, and have become core components of these high-performance electrochemical devices.

[0028] However, practical research and applications have revealed several bottlenecks in the long-term service life of existing integrated electrodes: First, electron transport in electrochemical devices relies on the conductive network within the integrated electrode, but volume expansion and mechanical stress during repeated charge-discharge cycles can easily cause the conductive network to break, leading to a continuous decline in the conductivity of the integrated electrode. Second, integrated electrodes are mostly porous structures with inherently insufficient mechanical strength, making them susceptible to bending and impact during assembly and use. Under long-term cycling or repeated high-current charge-discharge conditions, volume expansion and structural deformation can occur, causing the active material to lose effective contact with the integrated electrode substrate, resulting in active material detachment and damage to the integrated electrode, significantly shortening its service life. Third, to improve conductivity, a large amount of conductive agent or highly conductive structures are often introduced, but this can easily lead to a decrease in the overall mechanical strength and increased brittleness of the integrated electrode, making it prone to pulverization, detachment, and structural collapse during repeated charge-discharge cycles. In summary, it is difficult to synergistically improve the conductivity and mechanical properties of integrated electrodes in related technologies.

[0029] To address the aforementioned bottlenecks, various modification methods have been proposed in related technologies: the first method is single-performance modification, specifically, modifying conductivity alone, currently often using graphene and carbon nanotubes. Doping with conductive agents such as nanotubes (CNTs) is employed, as in patent document CN109236542A. However, most conductive agents are prone to aggregation, and their binding ability with the integrated electrode is weak, resulting in rapid conductivity decay after long-term charge-discharge cycles. Alternatively, mechanical properties can be modified separately, often by adding rigid reinforcing phases, as in patent document CN110534278A. However, reinforcing phases alone can easily disrupt the continuity of the conductive network, causing a trade-off between conductivity and mechanical properties. The second method involves adding a modification layer to the surface of the integrated substrate. However, existing modification layers often bind to the integrated electrode substrate through physical adsorption, resulting in insufficient interfacial bonding. This leads to modification layer detachment and active material peeling during long-term service, resulting in poor overall structural stability of the integrated electrode. The third method is high-temperature heat treatment modification, such as the modification at temperatures above 400°C in patent document CN111863219A. However, high temperatures can easily damage the structure of the active material in the integrated electrode, and process compatibility is also poor. The fourth method is simple component stacking.

[0030] In summary, while there are many modification methods available, there is a lack of effective ways to simultaneously and synergistically improve the conductivity and mechanical properties of integrated electrodes. In other words, the methods provided by related technologies almost all fail to fundamentally achieve synergistic enhancement of conductivity and mechanical properties, resulting in limited modification effects. Furthermore, conductivity and mechanical properties may mutually restrict each other, and there are also problems such as weak interfacial bonding in integrated electrodes, short service life of integrated electrodes, complex preparation processes, and poor environmental performance. As a result, it is difficult to meet the requirements of high-performance electrochemical devices.

[0031] Therefore, how to develop a modification method that combines synergistic optimization of structure and performance, strong interface bonding, and mild and environmentally friendly processes to simultaneously improve the conductivity, mechanical properties, and structural stability of integrated electrodes, so as to meet the industrialization requirements of high-performance electrochemical devices, has become a key technical problem that urgently needs to be solved in the development of integrated electrodes used in electrochemical devices such as lithium-ion batteries, supercapacitors, and fuel cells.

[0032] Based on the above, this application provides a method for synergistic modification of the conductivity and mechanical properties of an integrated electrode. For example... Figure 1 As shown, the method for synergistic modification of the conductivity and mechanical properties of the integrated electrode includes the following steps: S1. After selecting the electrode substrate, first use anhydrous ethanol (C2H5OH) to ultrasonically clean the electrode substrate for 10-20 minutes, then rinse it with deionized water 3-5 times, place it in a vacuum drying oven at 60-80℃ to dry for 2-4 hours, and then put it into a plasma processing instrument, using argon (Ar2) as the working gas, and activate it at a power of 50-100W for 5-15 minutes to obtain the pretreated electrode substrate.

[0033] In applications, the electrode substrate can be a carbon-based porous substrate, such as carbon felt, carbon cloth, carbon paper, etc. Among them, carbon felt can include polyacrylonitrile-based carbon felt, phenolic resin-based carbon felt, pitch-based carbon felt, viscose-based carbon felt, etc.

[0034] If the porosity of the carbon-based porous matrix is ​​too low (e.g., less than 50%), the conductive-reinforced composite modification liquid will have difficulty penetrating into the electrode matrix, forming only a composite modification layer on its surface with insufficient interfacial bonding. Conversely, if the porosity of the carbon-based porous matrix is ​​too high (e.g., greater than 85%), the electrode matrix itself will lack sufficient mechanical strength, and subsequent modifications will be difficult to effectively improve its overall mechanical properties. Therefore, in this application embodiment, the porosity of the electrode matrix is ​​set to 50-85%. For example, the porosity of the electrode matrix can be 50%, 60%, 70%, 80%, or 85%, etc., which allows the conductive-reinforced composite modification liquid to penetrate well into the electrode matrix, thereby resulting in good interfacial bonding and high mechanical strength of the electrode matrix.

[0035] In this embodiment, the areal density of the electrode substrate is set to 80-300 g / m³. 2 For example, the areal density of the electrode substrate can be 80 g / m². 2 100g / m 2 150g / m 2 200g / m 2 250g / m 2 Or 300g / m 2 Therefore, the electrode substrate is lightweight, easy to impregnate, easy to process, and has moderate strength.

[0036] In this embodiment, the initial volume resistivity of the electrode substrate is set to be less than or equal to 5 × 10⁻⁶. -3 Ω•cm, for example, the initial volume resistivity of the electrode substrate can be 1×10 Ω•cm. -3 Ω•cm, 2×10 -3 Ω•cm, 3×10 -3 Ω•cm, 4×10 -3 Ω•cm or 5×10 -3 Ω•cm, etc. This ensures that the electrode substrate and the subsequently formed conductive network (further, a three-dimensional conductive network) form a continuous conductive path, minimizing the risk that the overall conductivity improvement after modification may be limited due to the high initial resistance of the electrode substrate.

[0037] If the initial strength of the electrode substrate is too low, the integrated electrode is still prone to fracture even with excellent performance of the composite modification layer. Therefore, in this embodiment, the initial tensile strength of the electrode substrate is set to be greater than or equal to 50 MPa. For example, the initial tensile strength of the electrode substrate can be 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, or 100 MPa, etc. In this way, the electrode substrate can provide a solid foundation for improving the mechanical properties of the integrated electrode (e.g., by 35-50%).

[0038] The purpose of ultrasonically cleaning the electrode substrate with anhydrous C2H5OH for 10-20 minutes is to remove oil, impurities, etc. from the surface of the electrode substrate.

[0039] In applications, the plasma processor employs a plasma activation process, specifically plasma etching, which is a design feature tailored to the porous carbon-based structure of the electrode substrate. This involves forming micro / nano rough structures on the surface of the electrode substrate. The roughness Ra of these micro / nano rough structures is 0.5-2.0 μm. These structures include micrometer-scale and nanometer-scale structures. The size of the micrometer-scale structures is 0.1-100 μm, and the size of the nanometer-scale structures is 1-100 nm. For example, Ra can be 0.5 μm, 1.0 μm, 1.5 μm, or 2.0 μm, etc. The size of the micrometer-scale structures can be 0.1 μm, 1 μm, 10 μm, 50 μm, or 100 μm, etc., and the size of the nanometer-scale structures can be 1 nm, 20 nm, 40 nm, 60 nm, 80 nm, or 100 nm, etc. Simultaneously, active functional groups such as hydroxyl (-OH) and carboxyl (-COOH) groups are introduced into the micro / nano rough structures, with a density of active functional groups greater than or equal to 1.5 × 10⁻⁶. 15 pcs / cm 2 For example, the density of active functional groups can be 1.5 × 10⁻⁶. 15 pcs / cm 2 2×10 15 pcs / cm 2 2.5×10 15 pcs / cm 2 3×10 15 pcs / cm 2 3.5×10 15 pcs / cm 2 Or 4×10 15 pcs / cm 2 In this way, on the one hand, the mechanical bonding force between the composite modified layer and the electrode substrate is enhanced through "physical anchoring", and on the other hand, the functional group reaction lays the foundation for subsequent chemical bonding. At this time, the micro-nano rough structure can form "dual anchoring" with the porous structure of the electrode substrate, so that it can not only adhere to the surface of the electrode substrate, but also be embedded in the pores, significantly enhancing the interfacial bonding force.

[0040] The plasma treatment device further utilizes a power of 70-80W and a treatment time of 8-12 minutes. For example, the power of the plasma treatment device can be 70W, 72W, 74W, 76W, 78W, or 80W, and the treatment time can be 8 minutes, 9 minutes, 10 minutes, 11 minutes, or 12 minutes. This effectively removes trace amounts of ethanol, organic matter, oil, and weakly adsorbed impurities remaining on the electrode substrate surface after ultrasonication and water washing, resulting in a truly clean interface. Furthermore, the introduction of active functional groups such as -OH and -COOH significantly enhances surface energy and hydrophilicity, facilitating subsequent electrolyte wetting, bonding of active materials to the electrode substrate, and increasing the surface micro-roughness of the electrode substrate, providing more reaction and binding sites.

[0041] S2. Weigh out the following components by mass: 5-10 parts graphene; 3-6 parts CNTs; 2-5 parts conductive polymer; 1-3 parts dispersant; 2-4 parts binder; 0.5-2 parts reinforcing phase; 0.3-1 part silane coupling agent; and 80-100 parts mixed solvent. First, add the dispersant and silane coupling agent to the mixed solvent and stir at 300-500 r / min for 10-15 min until completely dissolved. Then, add the graphene, CNTs, and reinforcing phase, and disperse using a high-speed shear disperser at 10000-15000 r / min for 30-60 min. Finally, add the conductive polymer and binder and continue stirring for 20-30 min to obtain the conductive-reinforced composite modified liquid.

[0042] In applications, Graphene can be expressed in parts by weight, such as 5, 6, 7, 8, 9, or 10.

[0043] The diameter of a graphene sheet is 1-5 μm. For example, the diameter of a graphene sheet can be 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, etc.

[0044] Graphene can include reduced oxidative graphene, etc.

[0045] In applications, when the aspect ratio is less than 100, CNTs struggle to bridge graphene sheets to form continuous conductive channels, and the three-dimensional conductive network is prone to breakage. When the aspect ratio is greater than 500, CNTs easily entangle and agglomerate, and even dispersion under high-speed shear forces is difficult to completely deagglomerate, which in turn disrupts the uniformity of the conductive network. Therefore, in this application, the aspect ratio of the CNTs is set to 100-500. For example, the aspect ratio of the CNTs can be 100, 200, 300, 400, or 500, etc., thereby ensuring a continuous and uniform conductive network.

[0046] Raman spectroscopy I D / I G The ratio is used to reflect the degree of graphitization and surface defect density of CNTs. When Raman spectroscopy I... D / I G When the ratio is less than 0.5, the graphitization degree of CNTs is too high, the surface defects are few, the chemical bonding sites with the silane coupling agent are insufficient, and the interfacial bonding force is weak; while when the Raman spectrum I D / I G When the ratio is greater than 1.2, the graphitization degree of CNTs is too low, resulting in decreased conductivity and an inability to enhance conductivity. Therefore, the embodiments of this application set the Raman spectrum of CNTs to I D / I G With a ratio of 0.5-1.2, for example, the Raman spectrum of CNTs I D / I G The ratio can be 0.5, 0.7, 0.9, 1.0, 1.1, or 1.2, etc. This can result in CNTs with a suitable degree of graphitization and more surface defects, thus providing more chemical bonding sites with the silane coupling agent and stronger interfacial bonding, while also ensuring a high degree of graphitization and good conductivity, thereby exerting a better conductivity enhancement effect.

[0047] The surface carboxyl group content of CNTs is greater than or equal to 1.0 mmol / g. For example, the surface carboxyl group content of CNTs can be 1.0 mmol / g, 2.0 mmol / g, 3.0 mmol / g, 4.0 mmol / g, 5.0 mmol / g, or 6.0 mmol / g, etc. Thus, the carboxyl functional groups can chemically react with the -OH groups on the electrode substrate surface and the amino groups (-NH2) in the silane coupling agent to form stable chemical bonds. Simultaneously, it can also improve the dispersibility of CNTs in a mixed solvent of water (more specifically deionized water) and N-methyl-2-pyrrolidone (NMP), minimizing secondary agglomeration of CNTs during subsequent drying and curing.

[0048] The length of CNTs is 5-50 μm. For example, the length of CNTs can be 50 μm, 10 μm, 20 μm, 30 μm, 40 μm, or 50 μm. Such CNT length is adapted to the porosity (50-85%) of the electrode substrate. At this time, CNTs can be attached to the surface of the electrode substrate and embedded in the pores at the same time, forming a "surface-interior" dual conductive path, which further improves the overall conductivity of the integrated electrode.

[0049] CNTs can include carboxylated multi-walled carbon nanotubes (MWCNTs), carboxylated single-walled carbon nanotubes (SWCNTs), and so on.

[0050] The mass ratio of graphene to CNTs is 2:1-3:1. For example, the mass ratio can be 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, or 3:1. This forms a complementary three-dimensional conductive network of "two-dimensional framework-one-dimensional filler," where graphene provides a large-area conductive substrate, and CNTs fill the gaps between graphene sheets, achieving an interweaving density of 10-30 CNTs / μm. 2 This reduces the breakage of conductive channels.

[0051] In applications, conductive polymers may include one or more combinations of polyaniline (PAIN), polythiophene (PTh), polypyrrole (PPy), etc.

[0052] In applications, dispersants may include one or more combinations of sodium dodecylbenzene sulfonate (SDBS), polyethylene glycol (PEG), etc.

[0053] In applications, the binder may include one or more combinations of polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC-Na), styrene-butadiene rubber (SBR), etc.

[0054] In applications, the reinforcing phase may include one or more combinations of nano-alumina (Al2O3) and short-cut carbon (C) fiber composites, nano-silica (SiO2), and core-shell structures composed of Al2O3 and C (hereinafter referred to as Al2O3@C, where Al2O3 is the core, C is the shell, and C coats Al2O3).

[0055] The mass ratio of nano-Al2O3 to chopped C fibers is 1:1.

[0056] The shape of nano-Al2O3 is spherical, and its purity is greater than or equal to 99.5%. For example, the purity of nano-Al2O3 can be 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, or 100.0%, etc.

[0057] The average length of the chopped C fibers is 50-200 μm. For example, the average length of the chopped C fibers can be 50 μm, 100 μm, 150 μm, or 200 μm. Thus, the length of the chopped C fibers matches the porosity (50-85%) of the electrode substrate, allowing them to be embedded simultaneously in the pores of the electrode substrate and the conductive network of the composite modified layer, forming a gradient reinforcement structure of "electrode substrate-composite modified layer".

[0058] The diameter of the chopped C fibers is 5-15 μm. For example, the diameter of the chopped C fibers can be 5 μm, 8 μm, 12 μm, or 15 μm. This ensures, on the one hand, that the chopped C fibers possess sufficient mechanical strength and structural rigidity, forming a stable physical support framework within the integrated electrode. This significantly improves the tensile strength, flexural toughness, and impact resistance of the integrated electrode, reducing the risk of cracking and breakage under repeated charge-discharge cycles and mechanical stress. On the other hand, it allows the chopped C fibers to be uniformly dispersed in the conductive-reinforced composite modification liquid without easily agglomerating. This reduces dispersion difficulties and entanglement problems caused by excessively fine chopped C fibers, and also reduces defects such as uneven surface roughness and decreased bonding strength between the chopped C fibers and the composite modification layer caused by excessively coarse chopped C fibers. Simultaneously, the appropriate diameter allows the chopped C fibers to form a multi-level complementary conductive network with Graphene and CNTs, enhancing mechanical properties without compromising electrode conductivity, achieving a synergistic improvement in both mechanical reinforcement and conductivity.

[0059] The -COOH content on the surface of the chopped C fiber after oxidation treatment is greater than or equal to 0.8 mmol / g. For example, the -COOH content on the surface of the chopped C fiber after oxidation treatment can be 0.8 mmol / g, 0.9 mmol / g, 1.0 mmol / g, 1.1 mmol / g, 1.2 mmol / g, or 1.3 mmol / g, etc. This oxidation treatment can increase the -COOH content on the surface of chopped C fibers to greater than or equal to 0.8 mmol / g. On the one hand, it significantly improves the wettability and dispersion stability of chopped C fibers in the conductive-reinforced composite modification solution, reduces the aggregation and entanglement of chopped C fibers, and ensures the uniformity of the composite modification layer structure. On the other hand, -COOH can form hydrogen bonds and chemical bonds with silane coupling agents, binders, and active groups on the surface of the electrode substrate, enhancing the interfacial bonding strength between chopped C fibers and the conductive network and electrode substrate, thereby improving the structural stability and mechanical reliability of the integrated electrode. At the same time, an appropriate amount of surface -COOH can optimize the interfacial charge transport characteristics without significantly reducing the conductivity of chopped C fibers, further improving the overall conductivity of the integrated electrode and achieving a synergistic improvement in conductivity and mechanical reinforcement.

[0060] The aspect ratio of the chopped C fibers is 30-40. For example, the aspect ratio of the chopped C fibers can be 30, 32, 34, 36, 38, or 40. This allows the chopped C fibers to be evenly dispersed in the conductive-reinforced composite modification liquid and to prevent entanglement and agglomeration. This ensures that the chopped C fibers form a continuous and stable mechanical support network inside the integrated electrode, significantly improving the tensile strength, flexural toughness, and fatigue resistance of the integrated electrode. It also avoids problems such as entanglement and uneven dispersion of chopped C fibers caused by excessively large aspect ratios, and insufficient reinforcement effect caused by excessively small aspect ratios. At the same time, the chopped C fibers within this aspect ratio range can efficiently overlap with conductive components such as graphene and CNTs to form multi-level conductive pathways, strengthening mechanical properties without sacrificing conductivity, and achieving synergistic optimization of conductivity and mechanical reinforcement.

[0061] Thus, nano-Al2O3 and chopped C fibers form a synergistic reinforcement mechanism of "particle filling and fiber reinforcement". Nano-Al2O3 can fill the pores of the graphene-CNTs network and improve the structural density. At the same time, chopped C fibers bridge the nodes of the conductive network and bear the tensile stress under external force, reducing the brittleness of the composite modified layer. Moreover, the -OH on the surface of nano-Al2O3 and chopped C fibers will react with the silane coupling agent to ensure that the reinforcing phase is firmly anchored in the conductive network of the composite modified layer, reducing the risk of detachment due to repeated charge and discharge cycles.

[0062] The average particle size of the reinforcing phase is 50-200 nm. For example, the average particle size of the reinforcing phase can be 50 nm, 100 nm, 150 nm, or 200 nm. In this way, the reinforcing phase can be adapted to the pore size (100-300 nm) of the conductive network and achieve uniform filling.

[0063] Furthermore, the reinforcing phase is preferably a composite of nano-Al2O3 and chopped C fibers or Al2O3@C. The nano-Al2O3 and chopped C fiber composite can be embedded in the pores of the conductive network, forming a "point-surface-volume" mechanical support; the Al2O3 core of Al2O3@C provides mechanical support, while the C outer shell enhances compatibility with the conductive network.

[0064] Silane coupling agents can include one or more combinations of γ-aminopropyltriethoxysilane (KH550), γ-glycidoxypropyltrimethoxysilane (KH560), etc. The silane coupling agent simultaneously undergoes condensation reactions with -OH groups on the electrode substrate surface, -OH groups on the reinforcing phase surface, and oxygen-containing functional groups of Graphene / CNTs, forming chemical bonds to bridge these bonds and achieve structural interlocking between the conductive network and the enhanced mechanical properties.

[0065] The mass ratio of the reinforcing phase to the silane coupling agent is 1:0.3-1:0.8. For example, the mass ratio of the reinforcing phase to the silane coupling agent can be 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, or 1:0.8. This ensures that the silane coupling agent forms a uniform and complete coating modification layer on the surface of the reinforcing phase, fully introducing active functional groups to the surface of the reinforcing phase, significantly improving the dispersibility and wettability of the reinforcing phase in the conductive-reinforcing composite modification liquid, and reducing agglomeration and sedimentation. Furthermore, the interfacial bridging effect of the coupling agent enables stable chemical bonds to form between the reinforcing phase and the electrode matrix, conductive components, and binder, greatly improving the interfacial bonding strength and the overall structural stability of the integrated electrode. In addition, it reduces the problems of excessively thick interfacial insulation layer and decreased conductivity caused by excessive coupling agent, and insufficient interfacial modification and poor reinforcement effect caused by insufficient coupling agent, achieving synergistic optimization of conductivity and mechanical property enhancement.

[0066] In applications, the volume ratio of deionized water to NMP is 1:1 to 1:3. For example, the volume ratio of deionized water to NMP can be 1:1, 1:1.5, 1:2, 1:2.5, or 1:3. This allows the conductive-reinforced composite modified liquid to have suitable viscosity, wettability, and evaporation rate. This ensures that the conductive-reinforced composite modified liquid spreads evenly on the surface of the integrated electrode without dripping or accumulation, forming a dense and flat composite modified layer. It also takes into account the solubility and dispersion stability of each component in the mixed solvent, reducing the agglomeration or sedimentation of graphene, carbon nanotubes, and the reinforcing phase. At the same time, it can effectively reduce the amount of organic solvent used without damaging the structure of the electrode active material, improving process safety and environmental protection. Furthermore, it ensures that the solvent evaporates completely and leaves no residue during subsequent drying and heat treatment, guaranteeing the structural uniformity and interfacial bonding strength of the composite modified layer, which is conducive to the synergistic improvement of the conductivity and mechanical properties of the integrated electrode.

[0067] In applications, the purpose of high-speed shear dispersion is to ensure that each component is uniformly dispersed without agglomerates, and to ensure that the resulting conductive-reinforced composite modified liquid is uniform and stable.

[0068] It should be noted that there is no specific restriction on the order of steps S1 and S2. Step S1 can be executed first, followed by step S2; or step S2 can be executed first, followed by step S1.

[0069] S3. The conductive-reinforced composite modified liquid is uniformly coated onto the surface of the pretreated electrode substrate using a spraying method. The spraying pressure is controlled at 0.2-0.4 MPa and the spraying distance is 10-15 cm. The coated electrode is then placed in a forced-air drying oven at a temperature of 100-120℃ for 1-2 hours to allow the mixed solvent to evaporate and the binder to undergo initial cross-linking, thus obtaining a pre-cured modified electrode.

[0070] In applications, the spraying pressure for the spraying method is 0.2-0.4MPa and the spraying distance is 10-15cm. This ensures a coating thickness of 1-5μm and minimizes problems such as missed coating and accumulation.

[0071] S4. Place the pre-cured modified electrode in an inert gas atmosphere and a protective furnace with a flow rate of 100-400 mL / min, and perform staged heating heat treatment: First stage: heat to 200-250℃ at a heating rate of 3-10℃ / min and hold for 1-4 hours; Second stage: continue to heat to 300-350℃ at a heating rate of 3-10℃ / min and hold for 30-60 minutes.

[0072] In applications, inert gases may include nitrogen (N2), Ar, etc.

[0073] The protective furnace can be an inert gas heat treatment furnace, etc.

[0074] The heating rate in the first stage is further 7-8 °C / min, and the holding time in the first stage is preferably 1.5 h. For example, the heating rate in the first stage heat treatment can be 7.0 °C / min, 7.2 °C / min, 7.4 °C / min, 7.6 °C / min, 7.8 °C / min, or 8.0 °C / min, etc. In the first stage, the silane coupling agent can undergo a complete chemical bonding reaction, and the binder is fully cross-linked, thereby forming a stable bond between the composite modified layer and the electrode substrate.

[0075] The optimal holding time for the second stage is 45 minutes. In the second stage, residual small molecule impurities in the composite modified layer are removed, and the graphene and CNTs are further intertwined to form a conductive network with a porosity of 30-60%. This conductive network is continuous, allowing the reinforcing phase to be tightly embedded in the pores, thus constructing a "conductive-reinforcement" interlocking structure.

[0076] It should be noted that in the above-mentioned synergistic heat treatment and composite network reconstruction process, by strictly controlling the heat treatment temperature at 350℃ and below, the damage to the structure of the electrode active material can be reduced. Moreover, the staged heating heat treatment achieves "chemical bonding before network reconstruction", ensuring that interface bonding and dual performance optimization are achieved simultaneously.

[0077] S5. After the temperature inside the protective furnace has naturally cooled to room temperature, remove the electrode and lightly grind the edges of the electrode with a grinder to remove excess composite modified layer. Wipe the dust on its surface with anhydrous ethanol, and finally place it in a vacuum drying oven at a temperature of 60-80℃ for 1-2 hours to obtain an integrated electrode.

[0078] Based on the above, as an example, a plasma treatment power of 75W and a plasma treatment time of 10min were selected, resulting in a composite modified layer with a Ra of 1.2μm and an active functional group density of 2.3×10⁻⁶. 15 pcs / cm 2 The composite modification solution formulation is as follows: graphene, 8 parts; carbon nanotubes, 4 parts (graphene to carbon nanotube mass ratio of 2:1); PANI, 3 parts; SDBS, 2 parts; PVDF, 3 parts; Al2O3@C, 1.2 parts; KH550, 0.6 parts; deionized water, 30 parts; and NMP, 60 parts, totaling 90 parts. The heat treatment heating rate is 7.5℃ / min. The first stage is held at 220℃ for 1.5 h, and the second stage is held at 320℃ for 45 min. The nitrogen flow rate is 250 mL / min.

[0079] The integrated electrode conductivity and mechanical property synergistic modification method provided in this application embodiment 1. employs a dual interface enhancement method of "plasma interface activation and coupling agent chemical bonding," which can increase the peel strength between the composite modified layer and the electrode substrate by more than 80%, significantly improving the problem of weak interface bonding in related technologies; 2. designs a "graphene-carbon nanotube" complementary conductive network, and ensures continuous and stable conductive channels by precisely controlling the mass ratio and interlacing density, minimizing the aggregation defects of single conductive agents; 3. adopts an interlocking structure of "reinforcing phase embedded in the pores of the conductive network," which is not a simple component superposition, but a breakthrough... The dual performance constraints are overcome, thus enabling synergistic optimization of conductivity and mechanical support properties; 4. A two-stage, phased heat treatment process is adopted to achieve "chemical bonding before conductive network reconstruction," which maximizes the stability of the composite structure while avoiding damage to active materials; 5. The synergistic modification method is mature, and the plasma treatment equipment, high-speed shear disperser, spraying equipment, and protective furnace used are all existing industrial equipment, requiring no additional research and development of specialized equipment. Raw materials are readily available, costs are controllable, and the conductive-reinforced composite modification liquid can be prepared in batches, and the coating and heat treatment processes can be continuously produced, making it more suitable for annual production of 1 million cubic meters or more. 2 The above-mentioned large-scale production lines can also flexibly adjust the conductive-reinforced composite modified liquid formula and process parameters according to the performance requirements of different electrochemical devices. They have wide adaptability, simple and controllable process, are green and environmentally friendly, suitable for large-scale production, and have significant industrial application prospects and extremely high industrial application value.

[0080] This application embodiment also provides an integrated electrode. Figure 2 A scanning electron microscope (SEM) image of an integrated electrode according to an embodiment of this application is shown. (Reference) Figure 2 As shown, the integrated electrode comprises the integrated electrode prepared by the aforementioned method for synergistic modification of the conductivity and mechanical properties of an integrated electrode. The integrated electrode provided in this application includes an electrode substrate and a composite modification layer. The electrode substrate has a porous structure, and the composite modification layer has an interlocking network structure. The interlocking network structure includes a conductive network formed by interwoven graphene and carbon nanotubes, a reinforcing phase embedded in the pores of the conductive network, and silane coupling agent chemical bonds bridging the components and the electrode substrate. The interlocking network structure is combined with the porous structure.

[0081] It should be noted that the electrode substrate and composite modified layer in the embodiments of this application can refer to the above embodiments, and will not be repeated here.

[0082] In applications, the thickness of the composite modification layer is 1-5 μm. For example, the thickness of the composite modification layer can be 1 μm, 2 μm, 3 μm, 4 μm, or 5 μm. This thickness ensures the continuity and integrity of the conductive reinforcement network, achieving efficient modification, while avoiding cracking and detachment due to excessive thickness, which increases impedance, or modification failure due to excessive thinness, thus balancing structural robustness, conductivity, and process economy.

[0083] The porosity of the conductive network structure in the composite modified layer is 30-60%. For example, the porosity of the three-dimensional conductive network structure can be 30%, 40%, 50%, or 60%. This ensures the continuous continuity of the conductive network, allowing for rapid electron and ion transport, while buffering the cyclic deformation stress of the integrated electrode, reducing coating cracking, avoiding defects caused by excessively high or low porosity, and achieving a synergistic balance between conductivity and mechanical properties.

[0084] The interlacing density of the three-dimensional continuous conductive network in the composite modified layer is 10-30 strands / μm. 2 For example, the interlacing density of a three-dimensional continuous conductive network can be 10 strands / μm. 2 15 roots / μm 2 20 roots / μm 2 25 roots / μm 2 Or 30 roots / μm 2 This allows for the formation of a continuous conductive path, ensuring rapid electron transport, avoiding insufficient conductivity due to low density and agglomeration due to excessive density, thus balancing conductivity with coating uniformity and stability.

[0085] The peel strength between the composite modified layer and the electrode substrate is greater than or equal to 1.5 N / mm. For example, the peel strength between the composite modified layer and the electrode substrate can be 1.5 N / mm, 1.6 N / mm, 1.7 N / mm, 1.8 N / mm, 1.9 N / mm, or 2.0 N / mm, etc. This ensures a firm bond between the composite modified layer and the substrate, resists long-term cycling and mechanical impact, effectively prevents coating peeling or interface delamination, and guarantees the structural stability and service reliability of the integrated electrode.

[0086] The core of this composite modified layer is a conductive-reinforced composite network structure formed by a conductive-reinforced composite modified liquid. Specifically, it is a conductive network formed by interweaving graphene and CNTs in a mass ratio of 2:1 to 3:1. Graphene provides a two-dimensional conductive substrate, and CNTs fill the gaps between graphene sheets. The reinforcing phase is uniformly embedded in the pores of the conductive network and forms mechanical support sites. The silane coupling agent bridges the conductive network, the reinforcing phase, and the active functional groups on the electrode surface through chemical bonding. Finally, an interlocked composite network structure with both continuous electron transport and mechanical load-bearing capacity is constructed. This interlocked composite network structure and the porous structure of the electrode substrate form a gradient load-bearing system, further improving the overall mechanical stability of the integrated electrode.

[0087] In specific implementation, the integrated electrode in the embodiments of this application can be applied to electrochemical devices, including but not limited to lithium-ion batteries, supercapacitors, fuel cells, etc., and is especially suitable for porous integrated electrodes such as carbon felt, carbon cloth, and carbon paper.

[0088] The integrated electrode provided in this application embodiment employs a three-step core system of "plasma interface activation - conductivity - enhanced composite network construction - staged synergistic curing". First, plasma treatment is performed to obtain a micro / nano rough structure (Ra=0.5-2.0μm) and a high density of active functional groups (density greater than or equal to 1.5×10⁻⁶) on the surface of the electrode substrate. 15 pcs / cm 2 Then, a complementary conductive network containing graphene and carbon nanotubes was obtained (with an interlacing density of 10-30 nanotubes / μm). 2 The conductive-reinforced composite modified liquid, consisting of a "reinforcing phase-silane coupling agent" mechanical reinforcement system, was finally subjected to staged heat treatment to achieve the interlocking reconstruction of the conductive network and the mechanical support structure. This improved the peel strength between the composite modified layer and the electrode substrate to 80% or more. At the same time, the combination of graphene and carbon nanotubes into a complementary conductive network ensured the continuous and stable conductive channels, minimizing the agglomeration defects of single conductive agents. Furthermore, the reinforcing phase was embedded in the pores of the conductive network, achieving synergistic optimization of the conductivity and mechanical support performance of the integrated electrode, and optimizing the overall performance of the integrated electrode, which is beneficial for industrial production and application.

[0089] Based on the above, compared with the integrated electrodes in related technologies, the integrated electrode in this application embodiment can reduce the volume resistivity by 30-55%, increase the tensile strength by 35-50%, and increase the flexural toughness by 30-45%. Furthermore, the peel strength of the composite modified layer of the integrated electrode in this application embodiment is greater than or equal to 1.5 N / mm, the conductivity decay rate after 1000 bending cycles is less than or equal to 3%, and the capacity retention rate after 500 charge-discharge cycles is greater than or equal to 94%.

[0090] Example To verify the effectiveness of the integrated electrode in this application, multiple sets of embodiments and comparative examples were set up to test and compare the relevant performance of the integrated electrode. The following embodiments describe the disclosure of this application in more detail. These embodiments are for illustrative purposes only, as various modifications and variations within the scope of the disclosure of this application will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0091] Example 1 1. Pretreatment of the electrode substrate: An integrated carbon felt electrode for lithium-ion batteries was selected as the electrode substrate. It was first ultrasonically cleaned with anhydrous ethanol for 15 min, then rinsed with deionized water 4 times, dried in a vacuum drying oven at 80℃ for 3 h, and then placed in a plasma treatment instrument with Ar2 as the working gas and treated at 70W for 10 min to obtain the pretreated electrode substrate.

[0092] 2. Preparation of conductive-reinforced composite modified liquid: Weigh out the following by mass fractions: 8 parts of reduced oxidized graphene with a flake diameter of 3 μm; 4 parts of carboxylated MWCNTs with an aspect ratio of 300; 3 parts of PANI; 2 parts of SDBS; 3 parts of PVDF; 1.2 parts of Al2O3@C; 0.6 parts of KH550; and 90 parts of deionized water and NMP (30 parts of deionized water and 60 parts of NMP).

[0093] First, SDBS and KH550 were added to a mixed solvent of deionized water and NMP and stirred at 400 r / min for 12 min until completely dissolved. Then, reduced oxidized Graphene, carboxylated MWCNTs and Al2O3@C were added and dispersed at 12000 r / min for 45 min using a high-speed shear disperser. Finally, PANI and PVDF were added and stirring was continued for 25 min to obtain the conductive-reinforced composite modified liquid.

[0094] 3. Coating and preliminary curing of the conductive-reinforced composite modified liquid: Using a spraying method, under the conditions of a spraying pressure of 0.3 MPa and a spraying distance of 12 cm, the conductive-reinforced composite modified liquid was coated on the surface of the pretreated electrode substrate with a coating thickness of 3 μm. Then, it was dried by blowing air at a temperature of 110℃ for 1.5 h to obtain a pre-cured modified electrode.

[0095] 4. Synergistic heat treatment and reconstruction of conductive networks: The pre-cured modified electrode was placed in a protective furnace with N2 atmosphere and a flow rate of 250 mL / min, heated to 220℃ at a heating rate of 7.5℃ / min, and held at that temperature for 1.5 h. Then, the temperature was raised to 320℃ and held for 45 min to obtain the second modified electrode.

[0096] 5. Post-processing and finished product preparation: After the modified electrode is naturally cooled to room temperature, the cooled electrode is removed, the edges are polished and the surface is wiped, and then vacuum dried at 60°C for 2.0 h to obtain the final modified integrated electrode.

[0097] Example 2 1. Pretreatment of the electrode substrate: An integrated carbon cloth active electrode for supercapacitors was selected as the electrode substrate. It was first ultrasonically cleaned with anhydrous ethanol for 10 min, then rinsed three times with deionized water, dried in a vacuum drying oven at 70℃ for 2 h, and then placed in a plasma processor. Using Ar2 as the working gas, it was treated at 80W for 8 min to obtain the pretreated electrode substrate.

[0098] 2. Preparation of conductive-reinforced composite modified liquid: According to the mass fractions, weigh out 6 parts of reduced oxidized graphene with a flake diameter of 3 μm; 3 parts of carboxylated MWCNTs with an aspect ratio of 300; 2 parts of PTh; 1.5 parts of PEG; 2 parts of CMC-Na; 0.8 parts of nano-SiO2; 0.4 parts of KH560; and 85 parts of deionized water and NMP (40 parts of deionized water and 45 parts of NMP).

[0099] First, PEG and KH560 were added to a mixed solvent of deionized water and NMP and stirred at 400 r / min for 12 min until completely dissolved. Then, reduced oxidized Graphene, carboxylated MWCNTs and nano SiO2 were added and dispersed at 10000 r / min for 30 min using a high-speed shear disperser. Finally, PTh and CMC-Na were added and stirred for another 20 min to obtain the conductive-reinforced composite modified liquid.

[0100] 3. Coating and preliminary curing of the conductive-reinforced composite modified liquid: Using a spraying method, under the conditions of a spraying pressure of 0.2 MPa and a spraying distance of 10 cm, the conductive-reinforced composite modified liquid was coated on the surface of the pretreated electrode substrate with a coating thickness of 2 μm. Then, it was dried by blowing air at a temperature of 100℃ for 1.0 h to obtain a pre-cured modified electrode.

[0101] 4. Synergistic heat treatment and reconstruction of conductive networks: The pre-cured modified electrode was placed in a protective furnace with a N2 atmosphere and a flow rate of 200 mL. The temperature was increased to 200 °C at a rate of 8.0 °C / min and held for 1.0 h. Then the temperature was increased to 300 °C and held for 30 min to obtain the second modified electrode.

[0102] 5. Post-processing and finished product preparation: After the modified electrode is naturally cooled to room temperature, the cooled electrode is removed, the edges are polished and the surface is wiped, and then vacuum dried at 70°C for 1.5 hours to obtain the final modified integrated electrode.

[0103] Example 3 1. Pretreatment of the electrode substrate: An integrated carbon paper electrode for fuel cells was selected as the electrode substrate. It was first ultrasonically cleaned with anhydrous ethanol for 20 minutes, then rinsed with deionized water 5 times, dried in a vacuum drying oven at 60°C for 4 hours, and then placed in a plasma processor. Using Ar2 as the working gas, it was treated at a power of 100W for 15 minutes to obtain the pretreated electrode substrate.

[0104] 2. Preparation of conductive-reinforced composite modified liquid: According to the mass fractions, weigh 10 parts of reduced oxidized graphene with a sheet diameter of 3μm; 6 parts of carboxylated MWCNTs with an aspect ratio of 300; 5 parts of PPy; 3 parts of SDBS; 4 parts of SBR; 2.0 parts of nano-Al2O3 and short-cut carbon fiber composite; 1.0 part of KH550; and 100 parts of deionized water and NMP (25 parts of deionized water and 75 parts of NMP).

[0105] First, SDBS and KH550 were added to a mixed solvent of deionized water and NMP and stirred at 400 r / min for 12 min until completely dissolved. Then, reduced oxidized Graphene, carboxylated MWCNTs, and short-cut carbon fibers were added and dispersed at 15000 r / min for 60 min using a high-speed shear disperser. Finally, PPy and SBR were added and stirred for another 30 min to obtain the conductive-reinforced composite modified liquid.

[0106] 3. Coating and preliminary curing of the conductive-reinforced composite modified liquid: The conductive-reinforced composite modified liquid was coated onto the surface of the pretreated electrode substrate using a spraying method at a spraying pressure of 0.4 MPa and a spraying distance of 15 cm. The coating thickness was 5 μm. The substrate was then dried in a forced-air dryer at 120 °C for 2.0 h to obtain the pre-cured modified electrode.

[0107] 4. Synergistic heat treatment and reconstruction of conductive networks: The pre-cured modified electrode was placed in a protective furnace with N2 atmosphere and a flow rate of 300 mL / min. The temperature was increased to 250℃ at a rate of 10℃ / min and held for 2.0 h. Then the temperature was increased to 350℃ and held for 60 min to obtain the second modified electrode.

[0108] 5. Post-processing and finished product preparation: After the modified electrode is naturally cooled to room temperature, the cooled electrode is removed, the edges are polished and the surface is wiped, and then vacuum dried at 80°C for 1.0 h to obtain the final modified integrated electrode.

[0109] Comparative Example 1: The only difference between Comparative Example 1 and Example 1 is that the modification was carried out using the conductive agent doping method in the related art (i.e., only conductive modification), specifically, 5% by mass of Graphene was directly doped into the active material, while other aspects remained unchanged.

[0110] Comparative Example 2: The only difference between Comparative Example 2 and Example 1 is that the modification is carried out using mechanical methods from the relevant technology (i.e., mechanical modification only), while everything else remains the same.

[0111] Comparative Example 3: The only difference between Comparative Example 3 and Example 1 is that plasma pretreatment is not performed, while everything else remains the same.

[0112] Test section: The integrated electrodes of Examples 1-3 and Comparative Examples 1-3 were subjected to the relevant performance tests listed in Table 1 below according to the following methods. The test indicators included: volume resistivity, tensile strength, peel strength, capacity retention rate after 500 cycles, and bending attenuation rate after 1000 cycles. The test results are also shown in Table 1.

[0113]

[0114] As shown in Table 1, the volume resistivity of the integrated electrode in Example 1 decreased to 5.4 × 10⁻⁶. -4 Ω·cm (compared to 1.2×10 in related technologies) -3 The Ω·cm is reduced by 55%, and the tensile strength is increased to 116MPa (45% increase compared to 80MPa in the related technology).

[0115] In Example 2, the volume resistivity of the integrated electrode decreased to 5.1 × 10⁻⁶. -4 Ω·cm (compared to 8.5 × 10 in related technologies) -4 The Ω·cm is reduced by 40%, and the tensile strength is increased to 105 MPa (40% increase compared to 75 MPa in the related technology).

[0116] In Example 3, the volume resistivity of the integrated electrode decreased to 3.2 × 10⁻⁶. -4 Ω·cm (compared to 5.0 × 10 in related technologies) -4 The Ω·cm was reduced by 36%, and the tensile strength was increased to 130 MPa (44% increase compared to 90 MPa in the related technology).

[0117] Moreover, compared with Comparative Examples 1-3, Examples 1-3 have the following advantages: First, the embodiments of this application, through the synergistic design of "conductive network + mechanically reinforced interlocking structure," significantly improve the pain point of the mutual constraint between the conductivity and mechanical properties of integrated electrodes in related technologies; Second, the interfacial bonding force and structural stability are significantly enhanced: the dual effects of the "physical anchoring" of plasma pretreatment and the "chemical bonding" of the coupling agent increase the bonding force between the modified layer and the electrode substrate by more than 80%, and the "conductive-reinforced" interlocking structure can resist volume expansion and mechanical impact during charge-discharge cycles, effectively reducing the shedding of the composite modified layer and the stripping of active materials, and significantly extending the service life of the integrated electrode; Third, the process is environmentally friendly and controllable, suitable for large-scale production: this application uses water / NMP mixed solvent produces no toxic or harmful gas emissions, meeting green production standards. Furthermore, the heat treatment temperature is less than or equal to 350℃, reducing the risk of damage to active materials and preserving the original electrochemical activity of the integrated electrode. The spray coating and high-speed shear dispersion processes are mature, with easily adjustable parameters, allowing for flexible formulation adaptation to different electrode types, resulting in broad applicability. Fourthly, the technical solution provides ample support: the various technical features are not simply superimposed but form an organic whole. Plasma pretreatment provides the foundation for interfacial bonding, the component ratio of the composite modified liquid ensures structural synergy, and staged heat treatment achieves conductive network reconstruction. Each step works in concert to achieve a synergistic improvement in both performance characteristics.

[0118] Therefore, the integrated electrode obtained in this application embodiment has the following properties: in terms of conductivity, the volume resistivity can be reduced by 30-55% (existing single conductive modifications only reduce it by 20-30%), and the electron transport rate can be increased by 45-65%; in terms of mechanical properties, the tensile strength can be increased by 35-50% (existing single mechanical modifications only increase it by 15-25%), the bending toughness can be increased by 30-45%, and the peel strength is greater than or equal to 1.5 N / mm (in related technologies, it is less than or equal to 0.8 N / mm); in terms of stability, the conductivity decay rate after 1000 ±90° bending cycles is less than or equal to 3%; in terms of capacity retention, the capacity retention rate after 500 charge-discharge cycles is greater than or equal to 94% (in related technologies, it is 85-90%).

[0119] This section only introduces the content related to the invention point; other content can be obtained by referring to relevant technologies, and will not be explained in detail here.

[0120] Finally, it should be noted that the above descriptions are merely preferred embodiments of this application and are not intended to limit the application. Although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Therefore, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for synergistic modification of the conductivity and mechanical properties of an integrated electrode, characterized in that, Includes the following steps: An electrode substrate is selected, and after cleaning and drying, the surface of the electrode substrate is treated with plasma to obtain a pretreated electrode substrate. A composite modified liquid is obtained by first dissolving the dispersant and the silane coupling agent in the mixed solvent, then adding the graphene, the carbon nanotubes and the reinforcing phase, and shearing and dispersing them at a high speed of 10000-15000 r / min for a period of time, and finally adding the conductive polymer and the binder and mixing them. The composite modified liquid is coated onto the surface of the pretreated electrode substrate using a spraying method. The electrode coated with the composite modified liquid is then dried at a temperature of 100-120°C to allow the mixed solvent to evaporate and the binder to crosslink. A staged heat treatment is then performed under a protective atmosphere with a flow rate of 100-400 mL / min: first, the temperature is increased to 200-250°C at a rate of 3-10°C / min and held for a period of time; then, the temperature is increased to 300-350°C at a rate of 3-10°C / min and held for a period of time. After cooling and drying, the integrated electrode is obtained.

2. The method for synergistic modification of the conductivity and mechanical properties of an integrated electrode according to claim 1, characterized in that, The process of selecting an electrode substrate, cleaning and drying the electrode substrate, and then activating the surface of the electrode substrate using plasma to obtain a pretreated electrode substrate includes: After selecting the electrode substrate, the electrode substrate is first ultrasonically cleaned with anhydrous ethanol for 10-20 minutes, then rinsed with deionized water 3-5 times, and dried in a vacuum drying oven at 60-80℃ for 2-4 hours. Then it is placed in a plasma treatment instrument, with protective gas as the working gas, and activated at 50-100W power for 5-15 minutes to obtain the pretreated electrode substrate.

3. The method for synergistic modification of the conductivity and mechanical properties of an integrated electrode according to claim 1 or 2, characterized in that, The electrode substrate is a carbon-based porous substrate, which includes any one of carbon felt, carbon cloth, and carbon paper. The porosity of the electrode substrate is 50-85%; And / or, the areal density of the electrode substrate is 80-300 g / m³. 2 ; And / or, the initial volume resistivity of the electrode substrate is less than or equal to 5 × 10⁻⁶. -3 Ω•cm; And / or, the initial tensile strength of the electrode substrate is greater than or equal to 50 MPa; And / or, the surface of the electrode substrate is treated with the plasma to form a micro / nano rough structure, the roughness of which is 0.5-2.0 μm, the micro / nano rough structure comprising micrometer-scale and nanometer-scale structures, the size of which is 0.1-100 μm and the size of which is 1-100 nm, and active functional groups are introduced, the density of which is greater than or equal to 1.5 × 10⁻⁶. 15 pcs / cm 2 .

4. The method for synergistic modification of the conductivity and mechanical properties of an integrated electrode according to claim 1, characterized in that, The composite modified liquid comprises, by mass parts: Graphene, 5-10 parts; Carbon nanotubes, 3-6 parts; Conductive polymer, 2-5 parts; Dispersant, 1-3 parts; Adhesive, 2-4 parts; Reinforcing phase, 0.5-2 parts; Silane coupling agent, 0.3-1 part; Mixed solvent, 80-100 parts.

5. The method for synergistic modification of the conductivity and mechanical properties of an integrated electrode according to claim 4, characterized in that, The graphene sheet diameter is 1-5 μm; And / or, the graphene includes reduced graphene oxide; And / or, the aspect ratio of the carbon nanotubes is 100-500; And / or, the Raman spectrum of the carbon nanotubes I D / I G The ratio is 0.5-1.2; And / or, the surface carboxyl group content of the carbon nanotubes is greater than or equal to 1.0 mmol / g; And / or, the length of the carbon nanotubes is 5-50 μm; And / or, the carbon nanotubes include at least one of carboxylated multi-walled carbon nanotubes and carboxylated single-walled carbon nanotubes; The mass ratio of graphene to carbon nanotubes is 2:1 to 3:

1.

6. The method for synergistic modification of the conductivity and mechanical properties of an integrated electrode according to claim 4 or 5, characterized in that, The conductive polymer includes at least one of polyaniline, polythiophene, and polypyrrole; And / or, the dispersant includes at least one of sodium dodecylbenzenesulfonate and polyethylene glycol; And / or, the adhesive includes at least one of polyvinylidene fluoride, sodium carboxymethyl cellulose, and styrene-butadiene rubber; And / or, the average particle size of the reinforcing phase is 50-200 nm; the reinforcing phase includes at least one of the following: a composite of nano-alumina and chopped carbon fibers, nano-silica, and a core-shell structure composed of carbon-coated alumina; And / or, in the nano-alumina and chopped carbon fiber composite, the mass ratio of nano-alumina to chopped carbon fiber is 1:1, the nano-alumina is spherical in shape, and the purity of the nano-alumina is greater than or equal to 99.5%; the average length of the chopped carbon fiber is 50-200 μm, the diameter of the chopped carbon fiber is 5-15 μm, the carboxyl content on the surface of the chopped carbon fiber after oxidation treatment is greater than or equal to 0.8 mmol / g, and the aspect ratio of the chopped carbon fiber is 30-40; And / or, the mass ratio of the reinforcing phase to the silane coupling agent is 1:0.3-1:0.8; And / or, the mixed solvent comprises water and N-methylpyrrolidone, wherein the volume ratio of water to N-methylpyrrolidone is 1:1 to 1:

3.

7. The method for synergistic modification of the conductivity and mechanical properties of an integrated electrode according to claim 1 or 2, characterized in that, The spraying pressure in the spraying method is 0.2-0.4 MPa, and the spraying distance in the spraying method is 10-15 cm.

8. The method for synergistic modification of the conductivity and mechanical properties of an integrated electrode according to claim 1, characterized in that, The subsequent staged heat treatment under a protective atmosphere with a flow rate of 100-400 mL / min includes: first, heating to 200-250℃ at a heating rate of 3-10℃ / min and holding at that temperature for a period of time; then heating to 300-350℃ at a heating rate of 3-10℃ / min and holding at that temperature for a period of time. Then, a staged heat treatment is carried out under an inert gas atmosphere with a flow rate of 100-400 mL / min: first, the temperature is raised to 200-250℃ at a heating rate of 3-10℃ / min and held for 1-4 hours; then, the temperature is raised to 300-350℃ at a heating rate of 3-10℃ / min and held for 30-60 minutes.

9. An integrated electrode prepared by the method for synergistic modification of conductivity and mechanical properties of an integrated electrode as described in any one of claims 1-8, characterized in that, The integrated electrode includes an electrode substrate and a composite modified layer. The electrode substrate has a porous structure, and the composite modified layer has a network structure. The network structure includes a conductive network formed by the interweaving of graphene and carbon nanotubes, a reinforcing phase embedded in the pores of the conductive network, and a silane coupling agent bridging the components to the electrode substrate. The network structure is combined with the porous structure.

10. The integrated electrode according to claim 9, characterized in that, The thickness of the composite modified layer is 1-5 μm; And / or, the porosity of the conductive network is 30-60%; And / or, the interlacing density of the conductive network is 10-30 strands / μm. 2 ; And / or, the porosity of the conductive network is 30-60%; And / or, the peel strength between the composite modified layer and the electrode substrate is greater than or equal to 1.5 N / mm; And / or, the conductivity attenuation rate of the integrated electrode after 1000 bending cycles is less than or equal to 3%; And / or, the integrated electrode retains a capacity of 94% or more after 500 charge-discharge cycles.

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