Performance enhancement of graphene assisted CNT/Cu composites for lightweight electrical cables

Ultrastrong Carbon Nanotubes–Copper Core–Shell Wires with Enhanced Electrical and Thermal Conductivities as High-Performance Power Transmission Cables

“…As the annealing in the reducing atmosphere progresses, not only copper oxide residues will be reduced to copper, acidic/organic catalyst residues and moisture in the fiber were also removed. Furthermore, this process additionally assisted with the densification of CNT fiber, eliminating the micropores and gaps while enhancing contact between neighboring tubes, which lead to the strengthening effect. ,, It is noteworthy that the Cu grains of the annealed composite wires are larger than those prior to the heat treatment, which are in agreement with the results obtained by other researchers. , …”

“…To further reflect the electrical performance independent of the sample geometry, the specific electrical conductivity (σ sp ) and specific ampacity (Λ sp ) should be included in the study, as well. According to the definition, these parameters are defined as the electrical conductivity and ampacity divided by the density of the sample, which are calculated as follows: σ sp = σ 0.25em ( S cm ) ρ 0.25em ( g c m 3 ) = true I 0.25em ( mA ) U 0.25em ( mV ) l 0.25em ( cm ) A 0.25em ( c m 2 ) M 0.25em ( g ) V 0.25em ( c m 3 ) = σ 0.25em ( S ) 0.25em l 2 ( cm 2 ) M 0.25em ( g ) where σ is the electrical conductivity (S cm –1 ), U (V) and I ...…”

“…To further reflect the electrical performance independent of the sample geometry, the specific electrical conductivity (σ sp ) and specific ampacity (Λ sp ) should be included in the study, as well. According to the definition, these parameters are defined as the electrical conductivity and ampacity divided by the density of the sample, which are calculated as follows: where σ is the electrical conductivity (S cm –1 ), U (V) and I (A) refer to the voltage drop determined across the two inner probes and the current intensity going through the outer two probes. ρ is the density of the core–shell wire (g cm –3 ), and M (g), V (cm 3 ), A (cm 2 ), and l (cm) refer to the mass, the volume, the cross-sectional area, and the length of the core–shell wire sample. where I max (A) is the maximum current intensity that a wire can hold before it exceeds the temperature limit.…”

“…Simultaneously, annealing also promotes recrystallization and grain enlargement. Therefore, conductivity is further improved because the electron scattering is significantly hampered with larger grains after the annealing . Meanwhile, the synergism of a stronger adhesion, a better interfacial affinity between the Cu layer and CNT core, and a firmly connected Cu coating offered by surface functionalization and Cu pre-seeding decrease the electron scattering at the interface.…”

“…22,25,64 It is noteworthy that the Cu grains of the annealed composite wires are larger than those prior to the heat treatment, which are in agreement with the results obtained by other researchers. 26,65 The surface morphologies of CNTs−Cu core−shell wires with different surface functionalities after annealing are compared in Figure 2e−h. It is noted that Cu oxides formed on the Cu coating have been reduced to Cu.…”