What factors affect the electrical conductivity of nickel-based carbon nanotubes composites?
Release Time : 2025-10-29
The electrical conductivity of nickel-based carbon nanotube composites is a key research topic in materials science and engineering. Their performance directly impacts the efficiency and reliability of applications such as electronic devices, energy storage, and sensors. The conductivity of these composites is determined by the intrinsic properties of the nickel-based carbon nanotubes, the physicochemical properties of the nickel matrix, and the interfacial interactions between the two. This can be analyzed from the following perspectives.
The structural parameters of nickel-based carbon nanotubes are key factors influencing their electrical conductivity. Their conductivity stems from their unique electronic structure. Metallic nickel-based carbon nanotubes exhibit metallic-like conductivity due to varying chiral indices, while semiconducting nickel-based carbon nanotubes require doping to adjust their band structure. Thinner and longer nickel-based carbon nanotubes exhibit superior electrical conductivity, owing to the increased aspect ratio that extends the electron transport path and reduces defects. Furthermore, the purity and surface condition of nickel-based carbon nanotubes are crucial. Pure, defect-free tubes can achieve electrical conductivity several times that of copper. Surface oxidation or impurity adhesion significantly increases electron scattering, reducing electrical conductivity.
The crystal structure and surface energy of the nickel matrix modulate the conductivity of the composite. As a face-centered cubic metal, nickel's lattice constant and electron concentration directly influence electronic coupling with nickel-based carbon nanotubes. A nickel matrix with a low surface energy reduces wetting resistance to the nickel-based carbon nanotubes, promoting their uniform dispersion and preventing agglomeration-induced disruption of the conductive network. Furthermore, nickel crystallinity indirectly modulates conductivity by affecting electron mobility. In a highly crystalline nickel matrix, electron scattering at grain boundaries is reduced, improving overall conductivity.
Interfacial interactions are the key bridge connecting nickel-based carbon nanotubes to the nickel matrix. Chemical modification, by introducing oxygen- or nitrogen-containing functional groups on the surface of nickel-based carbon nanotubes, strengthens chemical bonding with nickel, forming stable electron transport pathways. Physical mixing relies on mechanical forces but is susceptible to conductivity degradation due to weak interfacial bonding. Optimizing the interface requires balancing chemical bond strength and electron transfer efficiency. For example, plasma treatment of the nickel-based carbon nanotubes' surfaces can preserve conductivity while enhancing interfacial adhesion with nickel.
Process parameters have a crucial influence on the conductivity of the composite. During electrodeposition, pulse frequency and negative working ratio control the electric field distribution, affecting the embedding depth and orientation of the nickel-based carbon nanotubes within the nickel matrix. High-frequency pulses refine nickel grains and reduce electron scattering; an appropriate negative working ratio promotes surface smoothing of the nickel-based carbon nanotubes, reducing contact resistance. Heat treatment temperature and duration further enhance conductivity by eliminating internal stress and repairing interfacial defects, but overheating should be avoided to prevent structural damage to the nickel-based carbon nanotubes.
The dispersion of the nickel-based carbon nanotubes directly influences the formation of the conductive network. Agglomerated nickel-based carbon nanotubes reduce contact points, disrupting electron transfer pathways and significantly reducing the conductivity of the composite. Through ultrasonic treatment, surfactant-assisted treatment, or functional modification, nickel-based carbon nanotubes can be individually dispersed within a nickel matrix, forming a three-dimensional conductive network. Electrons can then efficiently transport through the tunneling effect between the nickel-based carbon nanotubes or through the continuous nickel matrix.
Environmental factors have long-term effects on the conductive stability of nickel-based carbon nanotube composites. Increased humidity can induce surface oxidation of the nickel matrix, forming an insulating oxide layer that hinders electron transport. High temperatures can accelerate interfacial diffusion between the nickel-based carbon nanotubes and nickel, leading to structural changes in the conductive network. Furthermore, plastic deformation under mechanical stress can disrupt the synergistic deformation between the nickel-based carbon nanotubes and nickel, inducing microcrack propagation and further reducing conductivity.
The conductive properties of nickel-based carbon nanotube composites are a result of the combined effects of intrinsic material properties, interface design, fabrication process, and environmental adaptability. By optimizing the structural parameters of nickel-based carbon nanotubes, controlling the crystal structure of the nickel matrix, strengthening interfacial interactions, refining the preparation process, and improving environmental stability, the electrical conductivity of composite materials can be significantly improved, laying the foundation for their application in high-performance electronic devices and energy fields.