Spent Tea-Waste-Derived Porous Carbon-Supported Truncated Octahedral Cu₂O for Highly Efficient Energy Storage Devices

Abstract

In the present work, an active electrode material consisting of 60 wt % truncated octahedral-shaped Cu2O and 40 wt % spent tea-waste-derived porous carbon (PCTW) was synthesized (60Cu2O–40PCTW), which exhibited a specific capacity (CP) value of 1202.2 C g–1 in 3 M KOH and 2177.8 C g–1 in 3 M KOH + 0.1 M K4[Fe(CN)6] electrolyte systems. The composite was used as the cathode material and pure PCTW as the anode material to construct a flexible asymmetric supercapacitor (ASC) device with PVA gel entrapping 3 M KOH + 0.1 M K4[Fe(CN)6] as the electrolyte cum separator between the cathode and the anode. This ASC has the potentiality to supply an energy density of 112.8 Wh kg–1 at a power density of 1521.5 W kg–1 and can sustain 97% of its initial capacitance value after ∼10 000 galvanostatic charge–discharge (GCD) cycles. The device is also able to maintain uniform performances under various physically deformed states (bending angles 90°, 180°, and twisted), which indicates its excellent stability as well as flexibility. Hence, this work puts forward a clean energy storage device which is highly efficient and fulfills all of the required aspects of modern energy storage devices.