Deformation-free circular fibers derived from aqueous reduced graphene oxide for high-performance fiber supercapacitors

초록

Solution-processed graphene fibers are commonly fabricated by wet spinning of a liquid-crystalline (LC) graphene oxide (GO) dope, owing to the homogeneous aqueous dispersion of GO, strong hydrogen bonding, and nematic self-assembly. A straightforward route has thus been established for the formation of graphene fibers. However, during coagulation and subsequent chemical reduction, GO sheets consolidate into densely stacked fiber architectures, which often develop geo-metric non-uniformity due to anisotropic shrinkage during solvent exchange and reduction. Following chemical reduction, restacking and structural deformation occur, leading to the formation of large voids and ion-inaccessible volumes that reduce the ion-accessible surface area, thereby limiting their applicability in high-performance supercapacitors. Herein, deformation-free circular graphene fibers (GFs) are introduced via wet spinning using a hybrid ammonia-based graphene oxide (AGO)-reduced graphene oxide (rGO) composite dope. The AGO precursor preserves the intrinsic LC assembly characteristics of GO while offering improved dispersion stability and tunable intersheet interactions. The rGO component is engineered to retain stable aqueous dispersibility, enabling homogeneous co-dispersion with AGO sheets. Incorporation of rGO suppresses excessive LC-driven stacking and moderates solvent-coagulant exchange during extrusion, enabling rapid and homogeneous coagulation. In contrast to the layered architecture derived from conventional GO spinning, the rGO-rich hybrid fibers exhibit uniformly organized porous structures with effective pore sites. The mechanically rigid and chemically stable rGO forms a percolated structural framework that supports homogeneous electrical conductivity and mechanical strength while preserving high circularity with axial and radial uniformity. Consequently, the optimized AGO-rGO fibers exhibit enhanced electrical conductivity (567 S cm-1 after post-drawing) and improved electrochemical capacitance, demonstrating strong potential for high-performance fiber-shaped or wearable supercapacitors.

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