An Axially Continuous Graphene–Copper Wire for High‐Power Transmission: Thermoelectrical Characterization and Mechanisms (Adv. Mater. 51/2021)

Integration of an Axially Continuous Graphene with Functional Metals for High‐Temperature Electrical Conductors

“…J max is directly associated with excessive Joule heating and the subsequent thermal failure of wires, e.g., by melting. The wire temperature under electrical current density ( J ) is determined by resistivity‐dependent heat generation (∝ J 2 ρ ) [ 56 ] and size‐dependent surface heat dissipation (∝ q / d ) [ 45 ] where q is a coefficient of heat loss through the circumferential surface and d is diameter of a wire. This simple analysis indicates that a higher current density limit can be achieved by either reducing heat generation (i.e., lower ρ ) or increasing heat dissipation (i.e., smaller d ).…”

“…Fabrication of The Multilayer NiGCu Composite Wires: Multilayer graphene-coated Cu (GCu) wire was fabricated using CVD according to the procedure described in our previous report. [45] In brief, commercial Cu wires with 10, 25, and 80 μm in diameter and purity of 99.99% (California Fine Wire Company), were loaded into a CVD furnace as templates for CVD synthesis of graphene at 1000 °C. Before CVD growth, the Cu wires were annealed at 1000 °C underflow of 1500 sccm Ar and 100 sccm H 2 for 20 min for cleaning the wire surface and reducing preexisting oxides.…”

“…For graphene growth, chemical vapor deposition (CVD), a method for synthesizing large-scale and high-quality graphene, [50,51] was used to fabricate continuous multilayered graphene on fine Cu wires following our recent work. [45] Graphene was concurrently grown on several Cu wires with three different diameters (e.g., d cu = 10, 25, and 80 μm) at 1000 °C (Figure S1b, Supporting Information). This batch CVD process minimizes process-dependent variation among different wire samples.…”

“…Recently, this limitation has been addressed by synthesizing the continuous graphene networks in a metal matrix. [42][43][44] One notable approach, called axially continuous graphene-copper (ACGC) wires, [45] is assembly of axially continuous multilayered graphene with fine copper wires. The ACGC approach has demonstrated considerably higher charge-carrying capacity (450%), heat dissipation (224%), and electrical conductivity (41%).…”

“…The ACGC approach has demonstrated considerably higher charge‐carrying capacity (450%), heat dissipation (224%), and electrical conductivity (41%). [ 45 ] While ACGC wires exhibit improved thermal stability and oxidation resistance compared to pure Cu wires, their temperature range is still limited to 300 °C. It is worth noting that a carbon‐core and copper‐shell wire is also available for high electrical current applications, [ 31 ] but the copper shell, directly exposed to service environments, limits its operation temperatures (<200 °C).…”