Researchers have developed a method to produce graphene fibers with an exceptional combination of mechanical strength and thermal conductivity. The breakthrough relies on an ultrahigh-ratio drawing technique during the spinning process, which allows for near-perfect alignment of graphene sheets. These new fibers achieve a tensile strength of up to 2.1 GPa and a thermal conductivity of 1400 W·m⁻¹·K⁻¹, significantly outperforming previous graphene fibers and rivaling high-performance materials like alloy steels and pure copper, respectively.

The challenge in fabricating high-performance graphene fibers has been to achieve optimal alignment of graphene nanosheets within the fibrous structure. Previous methods often sacrificed one property for another or failed to achieve the necessary density and orientation. This new approach utilizes a wet-spinning process followed by intensive mechanical stretching, which induces reorientation and compaction of the graphene sheets, eliminating defects and improving structural continuity along the fiber axis.

The key to success lies in applying an extremely high drawing ratio, enabling an almost crystalline densification and alignment of the graphene sheets. This optimized microstructure not only enhances mechanical properties by more efficiently distributing loads but also facilitates phonon and electron transport, leading to superior thermal and electrical conductivity. The results pave the way for a new generation of lightweight, high-performance composite materials, as well as applications in flexible electronics and advanced thermal management.

The implications of this development are broad, ranging from improving aerospace and automotive components to creating smart textiles and more efficient electronic devices. The ability to produce graphene fibers with these properties at a potentially industrial scale represents a significant step towards the commercialization of graphene-based materials. Next steps will include optimizing manufacturing processes for large-scale production and exploring new applications where the unique combination of strength and conductivity is critical.