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

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.