Deep eutectic solvent and laser-reduced graphene oxide: Synergistic effects in ternary nanocomposite supercapacitors

Abstract

In recent years, flexible supercapacitors (FSCs) have gained considerable attention as reliable power supplies for wearable and portable electronic devices. However, optimizing both energy and power densities remains a challenge and requires effective enhancement of two key components: the electrolyte and the electrode. To address this, we have developed a new and efficient approach to FSC fabrication using a ternary nanocomposite of laser-reduced graphene@polyaniline/NiFe₂O₄(LrGO@Pani-NF) as the electrode and stable polymer hydrogels as the electrolyte. Also, we constructed FSC devices using a cross-linked poly (vinyl alcohol)/deep eutectic solvent (DES) gel electrolyte (PVA/ChCl/EG) and a PVA/Polyaniline/Nickel Ferrite gel electrolyte (PVA/Pani/NF). Among these devices, the LrGO@Pani-NF//LrGO@Pani-NF demonstrated a remarkable energy density of 48.4 Wh kg⁻¹ at 401.8 W kg⁻¹ and a long cycle life of 1000 cycles with 96.9 % capacity retention at 2 mA cm⁻². Furthermore, the supercapacitors assembled with the DES gel exhibited excellent stability at higher voltages, operating within a potential window of −3.0–3.0 V. This work not only enhances FSC electrochemical performance with graphene nanocomposite electrodes but also introduces a novel method for FSC design using conductive, stable gel electrolytes, thereby improving energy storage capabilities under harsh conditions.