Flexible, Tunable, Sewable Energy Storage Device

Technology #17262

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Similar to CNT yarns, niobium nanowire yarns are highly flexible and show potential for weaving into textiles and use in wearable devices. (A) Volumetric capacitance (with unit of MF·m−3 or F·cm−3 ) of bare Nb NW yarn (with an individual nanowire average diameter of 140 nm) as a function of the scan rate for a capacitor with a diameter of 85 μm per electrode and a separator thickness of 9 μm. (B) Scaling of the current (at 0 potential point) as a function of scan rate. At 20 V·s −1 , the current no longer increases in direct proportion to the scan rate. (C) Constant current charging and discharging of the supercapacitor before (blue, at 0.3, 1, 2, and 4 A·g−1 from right to left, respectively) and after (red, at 0.9, 1.5, 3, and 3.7 A·g−1 from right to left, respectively) depositing PEDOT (all per mass of dry electrode). (D) Nyquist plot of the PEDOT-coated supercapacitor (red); the inset shows the Nyquist plots for bare (blue) and PEDOT-coated (red) samples. (E) Bode plot of the supercapacitor before (solid line) and after (dashed line) PEDOT deposition
Professor Ian Hunter
Department of Mechanical Engineering, MIT
External Link (bioinstrumentation.mit.edu)
Seyed Mirvakili
Department of Mechanical Engineering, MIT
External Link (seyed.mit.edu)
Managed By
Christopher Noble
MIT Technology Licensing Officer - Clean and Renewable Energy
Patent Protection

High-Performance Supercapacitors Based on Metal Nanowire Yarns

US Patent Pending 2016-0064156

High-Performance Supercapacitors Based on Metal Nanowire Yarns

PCT Patent Application WO 2016-033514
High-Performance Supercapacitors from Niobium Nanowire Yarns
ACS Applied Materials and Interfaces, 2015, 7 (25), pp 13882–13888


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.

Problem Addressed

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