Niobium nanowire (Nb NW) yarns are highly chemically stable, hypoallergenic, biocompatible, and bioinert materials, which makes them applicable for use in jewelry, biomedicine, surgical tools, or wearable technologies.
The large ion-accessible surface area of carbon nanotubes (CNTs) enables miniature high-performance super capacitors with high power and energy densities. Ultra-long Nb NWs show higher capacitance and energy per volume than similarly spun CNTs. Furthermore, Nb NWs are stronger and 100 times more conductive than CNTs.
Niobium nanowires are extracted from copper-niobium composite wires by etching the copper. Identical electrodes are made after extraction by adding a small amount of twist to each yarn. For wet cells, acidic electrolytes show the best performance, and for dry cells, gels doped with acids can be used (e.g. polyvinyl alcohol (PVA) with sulfuric acid). Micron-sized cellulosic wood pulp fibers were used as the separator and electrolyte absorber. To boost the performance, poly(3,4-ethylenedioxythiophene) (PEDOT) - a conducting polymer - was deposited on the electrodes. Peak power and energy densities of 55 W cm-3 and 7mWh cm-3 were measured for Nb NW yarns, which are 2 and 5 times higher than that for state-of-the-art CNT yarns, respectively. Gravimetric and volumetric capacitance limits of Nb NW yarns were found to be 1.5x107 F m-3, which is 3 times higher than CNT yarns. Because the capacitance is volume dependent, it can be tuned by cutting the yarn along the length of the twisted pair.
Increases capacitance, energy per volume, strength and conductivity
Niobium nanowire yarns are hypoallergenic, chemically
stable, biocompatible, and bioinert
Niobium nanowire yarns are flexible, tunable, and sewable