A facile approach to investigate the charge storage mechanism of MOF/PANI based supercapattery devices

Abstract

Supercapattery a combo of supercapacitors and batteries that embraces the features of both technologies in a single assembly. To justify this claim, a systematic approach has been employed to evaluate the performance of the combo device. In this regard a novel material is synthesized via hydrothermal technique and later on physically blended with polyaniline (PANI) to boost the performance of the pristine material. This matrix material expresses excellent performance by showing a specific capacity of 154 C/g in cyclic voltammetry (CV) and 162 C/g in galvanostatic charge discharge (GCD). Furthermore, this electrode material was sandwiched with activated carbon to fabricate the supercapattery device. The supercapattery performance was evaluated through CV, GCD, and electrochemical impedance spectroscopy (EIS). This device indicates a specific capacity of 104 C/g, 23.11 Wh/kg specific energy, and 6400 W/kg of specific power. Finally, a theoretical Dunn's model was applied to eliminate the faradaic and non-faradaic contribution of the real device. It was evidenced that the device storage was not purely faradaic (diffusive) neither non-faradaic (capacitive), but it is the combination of both contribution. The capacitive and diffusive contribution was found dependent on the scan rate and was due to the time offered to the ions for interaction with the electrode material. Our study offers the development of novel metal-organic framework/polyaniline-based electrode material for supercapattery devices as well as a unique route to probe the performance of the supercapattery.