Microfluidic Spinning of Core–Shell α-MnO2@graphene Fibers with Porous Network Structure for All-Solid-State Flexible Supercapacitors

Fiber-shaped supercapacitors are desirable candidates for flexible and wearable energy storage devices; however, the ultralow capacitance and intricate fabrication process of electrode materials significantly limits their performances. We exploited a steerable method to generate core–shell α-MnO2/graphene fibers (MnGFs), where the sheath of α-MnO2 with porous network structures were grown in situ intertwined on the core of graphene fiber in a microfluidic-spinning strategy. The as-obtained MnGFs exhibited outstanding mechanical flexibility and could be curled over a teflon rod for continuous production. Furthermore, the fiber-shaped supercapacitors (MGSCs) manufactured with MnGFs were successfullu assembled and exhibited good voluminal specific capacitance (136.7 F cm−3), prominent cyclic stability (91.6% retention over 10000 cycles), and high energy density (3.9 mWh cm−3). This advantageous performance was achieved by MnGFs with porous network structures, leading to the rich ion pseudo-capacitance and numerous electron transport channels. The as-prepared MGSCs could be easily adopted to power 5 light-emitting diodes after completel charging. We believe that our microfluidic spinning strategy can provide a new-style structural design method for efficient electrode materials and promote the progress of wearable electronic products.