(Invited) Design Principles of High Voltage Asymmetric Supercapacitors Based on Electrode Energetics

Abstract

As the global appetite for clean energy is growing like never before, energy storage devices like supercapacitors are attracting considerable attention. With the advent of nanotechnology and the development of advanced materials, many researchers are focused on developing new nanomaterials and nanostructures to improve the energy storage capacity of these interesting devices. However, a major limitation for its widespread application as an energy storage device is its inferior energy density compared to Li-ion batteries, though their power density is much higher. An approach to achieve high energy density is to increase the voltage output of supercapacitors. Developing high-performing asymmetric supercapacitors is a viable direction to achieve this goal. To develop asymmetric supercapacitors, two different materials are used as anode and cathode. Currently, clear guidelines to select these two different materials are missing. A reason for this void is the complex involvement of multiple factors related to electrodes and electrolytes that determine the voltage window. In this talk, the importance of the work-function of electrodes in designing a high voltage asymmetric supercapacitor will be discussed. This would help understand the energetics of electrode-electrolyte interaction, which governs the output voltage window while the supercapacitor is in operation. It enables to better design supercapacitors with higher voltage window and thus increased energy density. We will also talk about the electrode-electrolyte interaction and the influence of hydrogen and oxygen evolution overpotential on the voltage of asymmetric supercapacitors.