Printed and Flexible NiO Supercapacitors for Energy Harvesting Applications

Name of the conference: Innovations in Large Area Electronics (InnoLAE)

Date of publication: 22-23 January 2019

Abstract: Harvesting energy from various ambient energy sources including electromagnetic/RF, thermal, mechanical, solar opens opportunities for the development of self-powered wireless sensors, internet-of-things devices and autonomous wearable electronics. Energy harvesters tend to deliver ¨packets¨ of energy with lots of power fluctuations, and supercapacitors represent an ideal energy storage solution as devices capable of handling high power densities, sustaining millions of charge/discharge cycles at fast rates. In this work we have developed a fully inkjet-printed and flexible nickel (II) oxide (NiO) co-planar supercapacitor to support the energy storage demands of next generation wearable electronics. The supercapacitor is prepared by ink-jet printing the current collector of the device in a co-planar configuration followed by deposition of the active electrode layers using a NiO nanoparticle ink (<50 nm particle size). Finally, a quasi-solid neutral electrolyte is inkjet printed on top to assemble the full device. Cyclic voltammetry analysis showed a maximum capacitance of 77 F·cm-3 and 3.1 mF·cm-2 for a wide range of scan rates from 10 mV·s-1 to 250 mV·s-1. The devices showed excellent capacitive response even at as high as 1500 mV·s-1 of scan rate. The power density of the device was evaluated to be 3.81 W·cm-3. The nanoparticle-defined NiO electrodes form a well-structured mesoporous layers that facilitate high ionic transport during charge/discharge cycles while also enabling high electrode conductivity. These results show the potential of nanostructured NiO for high performance, thin film and flexible supercapacitors that can be realised via roll-to-roll fabrication techniques compatible with printed electronics.