Characteristics of Inkjet-Printed Separators in Graphene-Based Supercapacitors

Abstract

Electrochemical capacitors such as a supercapacitor store electrical charge on high-surface-area conducting materials.1,2 Supercapacitors store energy by forming a double layer of electrolyte ions on the surface of conductive electrodes. They are not limited by the electrochemical charge transfer kinetics of batteries and thus can operate at very high charge and discharge rates. Graphene is a promising material for energy storage, especially for high performance supercapacitors. For real time high power applications, it is critical to have high specific capacitance with fast charging time at high current density.3,4 In this study, we prepared the separators of supercapacitors on cellulous films and papers by using an inkjet printing technology. Several different ink materials such as carbon nanotubes and metal oxides were introduced and the influence of the base materials used as separator was also investigated. The supercapacitors with a graphene nanoparticle composite as electrodes showed a specific capacitance of up to 100 F/g. The inkjet printing conditions such as pulse voltages and pressures were carefully controlled to maximize the performance of supercapacitors. The interface topologies and electric properties of the so formed supercapacitors were investigated by a scanning electron microscope and the measuring system of charge-discharge cycles, respectively.