Here, the fabrication of nonwoven fabric by blow spinning and its application to smart textronics are demonstrated. The blow-spinning system is composed of two parallel concentric fluid streams: i) a polymer dissolved in a volatile solvent and ii) compressed air flowing around the polymer solution. During the jetting process with pressurized air, the solvent evaporates, which results in the deposition of nanofibers in the direction of gas flow. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) dissolved in acetone is blowspun onto target substrate. Conductive nonwoven fabric is also fabricated from a blend of single-walled carbon nanotubes (SWCNTs) and PVdF-HFP. An all-fabric capacitive strain sensor is fabricated by vertically stacking the PVdF-HFP dielectric fabric and the SWCNT/PVdF-HFP conductive fabric. The resulting sensor shows a high gauge factor of over 130 and excellent mechanical durability. The hierarchical morphology of nanofibers enables the development of superhydrophobic fabric and their electrical and thermal conductivities facilitate the application to a wearable heater and a flexible heat-dissipation sheet, respectively. Finally, the conductive nonwoven fabric is successfully applied to the detection of various biosignals. The demonstrated facile and cost-effective fabrication of nonwoven fabric by the blow-spinning technique provides numerous possibilities for further development of technologies ranging from wearable electronics to textronics.

Harsh oxidation of 1 nm single-walled carbon nanotubes (SWCNTs) can lead to fatal defect structures, which can jeopardize their mechanical and electrical performances. Here, we show the structural recovery of highly oxidized SWCNTs (Ox-SWCNTs), which were rapidly (within 1 h) oxidized by kneading without forming failurecausing defects inspired by flour dough. The rational oxidation of SWCNTs by kneading debundled the SWCNTs and led to obtaining thermodynamically stable SWCNT solutions in water or even in alcohol without dispersant molecules. Importantly, the structure of the Ox-SWCNTs could be recovered by chemical, thermal, photothermal, or solvothermal reduction, enhancing the electrical conductivity of the Ox-SWCNT films from ∼100 to ∼1000 S cm −1 . These Ox-SWCNTs and chemically reduced Ox-SWCNTs showed high performance in supercapacitors and Li-ion batteries as electrochemical conductors, respectively.

Compared with traditional metal-oxide lithium-ion battery (LIB) cathodes, nanocarbon-based cathode materials have received much attention for potential application in LIBs because of their superior power density and long-term cyclability. However, their lithium-ion storage capacity needs further improvement for practical applications, and the trade-off between capacity and conductivity, when oxygen functional groups as lithium-ion storage sites are introduced to the nanocarbon materials, needs to be addressed. Here, we report a sequential oxidation–reduction process for the synthesis of single-walled carbon nanotubes (SWCNTs) for LIB cathodes with fast charging, long-term cyclability, and high gravimetric capacity. A LIB cathode based on highly exfoliated (d bundle < 10 nm) and oxygen-functionalized single-walled carbon nanotubes is obtained via the modified Brodie’s method using fuming nitric acid and a mild oxidant (B-SWCNTs). Post treatment including horn sonication and hydrogen thermal reduction developed surface defects and removed the unnecessary C–O groups, resulting in an increase in the Li-ion storage capacity. The B-SWCNTs exhibit a high reversible gravimetric capacity of 344 mA h g–1 at 0.1 A g–1 without noticeable capacity fading after 1000 cycles. Furthermore, it delivers a high gravimetric energy density of 797 W h kgelectrode –1 at a low gravimetric power density of 300 W kgelectrode –1 and retains its high gravimetric energy density of ∼100 W h kgelectrode –1 at a high gravimetric power of 105 W kgelectrode –1. These results suggest that the highly exfoliated, oxygen-functionalized single-walled carbon nanotubes can be applied to LIBs designed for high-rate operations and long cycling.

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