Ultrastiff and Strong Graphene Fibers via Full-Scale Synergetic Defect Engineering
Graphene has been recognized as the ideal building block for making multifunctional, high-performance carbonaceous fi bers since it can be readily produced from natural graphite, a cheap and abundant nonpetroleum carbon allotrope. [ 1–5 ] More importantly, graphene has many extraordinary properties including the highest tensile strength (130 GPa), Young’s modulus (1100 GPa), electrical conductivity (10 8 S m −1 ), ampacity (10 12 –10 13 A m −2 ), and record thermal conductivity (5300 W m −1 K −1 ). [ 1,2 ] Such amazing merits of individual graphene sheets are expected to be translated into the macroscopically assembled graphene fi bers (GFs). [ 3–5 ] GFs can be deemed to be a new carbonaceous fi ber species which is signifi cantly distinct from conventional carbon fi bers (CFs). First, GFs are prepared from graphite, whereas CFs are fabricated from natural or synthetic polymers and pitch molecules by oxidation and pyrolysis. Second, GFs are composed of wellaligned graphene sheets along the fi ber axis, and CFs consist of graphite nanocrystals that are interconnected in a turbostratic structure. Third, the lateral crystal size of graphene sheets can be much larger than that of CFs, by three orders of magnitude at the most, which could endow GFs high mechanical performance and advanced functionalities, such as thermal and electrical conductivities.