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

Abstract

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-MnO 2 /graphene fibers (MnGFs), where the sheath of α-MnO 2 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 pseudocapacitance 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.

Review on Microfluidic Construction of Advanced Nanomaterials for High-Performance Energy Storage Applications

“…As shown in Figure 4c, Shao et al developed graphene fiber by microfluidic self-assembly, which exhibited good flexibility and conductivity. 134 The graphene fiber-based supercapacitor showed an energy density of 3.9 mWh cm −3 because of abundant electron transport channels. Moreover, with in situ growth of the polyaniline nanorod arrays, 92 the microfluidic-oriented core−sheath polyaniline nanorod array/ graphene (PNA/G) fiber with high conductivity and impressive pseudo-capacitance displayed a high energy density of 37.2 μWh cm −2 .…”

“…(c) Microfluidic construction of a graphene-based microfiber by the self-assembly reaction. This figure was reproduced with permission from ref . Copyright 2021 The Electrochemical Society.…”

“…Especially, the graphene fiber based on the microfluidic self-assembly reaction possesses excellent mechanical flexibility, lightweightness, and uniform conductive network, which is considered as a promising electrode material in fiber-based supercapacitors and batteries. As shown in Figure c, Shao et al developed graphene fiber by microfluidic self-assembly, which exhibited good flexibility and conductivity . The graphene fiber-based supercapacitor showed an energy density of 3.9 mWh cm –3 because of abundant electron transport channels.…”

High Areal Capacitance of Flexible Supercapacitors Fabricated with Carbon Cloth-Carbon Fiber-TiO2 Electrodes and Different Hydrogel Polymer Electrolytes

“…Flexible electrodes used for SCs should be customarily electrically conducting, chemically stable, light weight, environmental-friendly and sufficiently mechanically stable without compromising with their flexibility. [21][22][23] Carbon fabric namely carbon cloth (CC) is considered as one of the most attracted electrode substrates for flexible SCs due to its light weight, low-cost, good flexibility, electrical conductivity, large surface area, and high mechanical stability. There are also other flexible electrode substrates known in the literature such as polyester textile, plastics, cotton fabrics, and cellulose papers.…”