NiO hybrid nanoarchitecture-based pseudocapacitor in organic electrolyte with high rate capability and cycle life

A 3D hierarchical NiO nanostructures with combined microstructure of nanoflakes and nanoflowers have been fabricated on carbon fibre cloth (CFC). Unique nano-micro structural features of NiO/CFC electrode showed an enhanced electrochemical activity in organic electrolyte (1 M tetraethylammonium tetrafluorborate (TEABF₄) in propylene carbonate) in terms of rate capability, specific energy and power performance as well as potential limit. The electrode showed a specific capacitance of 170 Fg⁻¹ for a current density of 5 Ag⁻¹. Configured as a two-electrode symmetric supercapacitor, the device showed a specific capacitance of 34.9 Fg⁻¹ at 1 Ag⁻¹ current density. It delivered a maximum specific energy density of 19.4 Wh kg⁻¹ at a high power density of 1002.8 W kg⁻¹ at a constant current density of 1 Ag⁻¹. The cell is also capable of long-term cycling stability with an efficiency of 58 % after 25,000 cycles with a potential window of 0 to ±2 V. This superior electrochemical activity of the NiO electrode is due to their structural benefits of well-connected hybrid nano/mesoporous structure and rapid ion intercalation within the porous electrode surface.