3 years ago

Vertically Aligned Niobium Nanowire Arrays for Fast-Charging Micro-Supercapacitors

Vertically Aligned Niobium Nanowire Arrays for Fast-Charging Micro-Supercapacitors
Ian W. Hunter, Seyed M. Mirvakili
Planar micro-supercapacitors are attractive for system on chip technologies and surface mount devices due to their large areal capacitance and energy/power density compared to the traditional oxide-based capacitors. In the present work, a novel material, niobium nanowires, in form of vertically aligned electrodes for application in high performance planar micro-supercapacitors is introduced. Specific capacitance of up to 1 kF m−2 (100 mF cm−2) with peak energy and power density of 2 kJ m−2 (6.2 MJ m−3 or 1.7 mWh cm−3) and 150 kW m−2 (480 MW m−3 or 480 W cm−3), respectively, is achieved. This remarkable power density, originating from the extremely low equivalent series resistance value of 0.27 Ω (2.49 µΩ m2 or 24.9 mΩ cm2) and large specific capacitance, is among the highest for planar micro-supercapacitors electrodes made of nanomaterials. Fast-charging micro-supercapacitors are made from vertically aligned niobium nanowire arrays. Thanks to the high electrical conductivity of the nanowires, the micro-supercapacitor exhibits a very small characteristic relaxation time constant of 8.4 ms. With 1 m sulfuric acid, cycling rates of up to 300 V s−1 are achieved, while with 1-ethyl-3-methylimidazolium tetrafluoroborate, an operating voltage of up to 4 V is obtained.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/adma.201700671

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