Asymmetric photo-assisted supercapacitor and symmetric flexible supercapacitors based on CeO2-MnO2 supported on carbon cloth

Abstract

In this study, a simple one-step hydrothermal method was developed to synthesize ceria-manganese oxide nanoparticles on carbon cloth (CeM/CC) that exhibit excellent supercapacitive properties. The structures, morphologies, and electrochemical properties of the produced materials were characterized in various tests. In addition, we fabricated two types of supercapacitors for the first time: a symmetric flexible supercapacitor (SFSC) and an asymmetric photo-assisted supercapacitor (APSC), both based on the optimal cerium manganese oxide sample on carbon cloth. The SFSC was constructed with CeM-50:50 electrodes as positive and negative electrodes and PVA-Na₂SO₄ as gel polymer electrolyte. The APSC was assembled with a CeM-50:50/CC electrode and a CeM-50:50/FTO photoelectrode as the photosensitive component. The fabricated SFSC device exhibited a maximum energy density of 0.024 mWh/cm³ at a power density of 0.306 mW/cm³ and showed exceptional flexibility and long-term durability with a capacity retention of more than 95% over 4000 charge/discharge cycles. The specific capacitance of the photo-assisted ASC is higher in light, showing a significant increase in areal capacitance (4.80 mF/cm²) compared to dark conditions (2.78 mF/cm²) at the same current density. This is the first report of a simple and successful fabrication of flexible supercapacitors and photo-assisted supercapacitors based on CeM/CC for photoelectrochemical energy storage systems. These light-sensitive devices offer significant opportunities to improve the use of solar energy and optimise energy storage applications.