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 alpha-MnO2/graphene fibers (MnGFs), where the sheath of alpha-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.

Automated summary

A steerable method was utilized to generate core-shell alpha-MnO2/graphene fibers, exhibiting outstanding mechanical flexibility and advantageous performance in fiber-shaped supercapacitors. The high voluminal specific capacitance, cyclic stability, and energy density were achieved due to the porous network structures of the MnGFs. The microfluidic spinning strategy could potentially promote the progress of wearable electronic products by providing a new-style design method for efficient electrode materials.