Ultrathin Ni-Mo oxide nanoflakes for high-performance supercapacitor electrodes

Supercapacitors based on nanomaterial electrodes exhibit great potential as power sources for advanced electronic devices. From a practical viewpoint, it is desirable to fabricate highly active and sustainable nanomaterial electrodes consisting of non-precious elements using a simple technique in a controllable way. In this work, we report the synthesis of a self-assembled ultra-thin porous nanoflake Ni-Mo oxide (NMO) film using the successive ionic layer adsorption and reaction (SILAR) technique. The nanoflake NMO thin film electrode with a large electrochemically active surface area of ∼108 cm−2 exhibits a high specific capacitance of 1180 Fg−1 at a current density of 1 Ag−1 and excellent rate capability, with a negligible capacity loss of 0.075% per cycle. Even at a high current rate of 10 A g−1 it retains a capacity of 600 Fg−1. The highest energy and power densities obtained are 119 Whkg−1 and 15.7 kWkg−1, respectively. Electrochemical impedance spectroscopy analyses reveal that the electrode has considerably low charge transfer resistance. The observed excellent electrochemical energy storage performance of the nanoflake NMO electrode with a nanoporous surface is due to the synergetic effects of the large electrochemically active surface area, enhanced ion diffusion, and improved electrical conductivity.