A ternary MnO2-deposited RGO/ lignin-based porous carbon composite electrodes for flexible supercapacitor application
The MnO2 nanoparticles with high theoretical capacitance were successfully synthesized on the reduced graphene oxide/lignin-based porous carbon (RGO/PC) composite membrane by simple electrodeposition method, and a ternary RGO/PC/MnO2 composite electrode for flexible supercapacitors was prepared. The RGO/PC/MnO2-1200s composite electrode exhibited a maximum specific capacitance of 1136mF/cm2 (MnO2 loading mass of 6.25mg/ cm2 and the mass specific capacitance of 135F/g) at a current density of 1mA/cm2.This is attributed to the high surface area of the MnO2 nanoparticles and the conductive pathway provided by the RGO/PC framework. The assembled flexible solid-state symmetric supercapacitors have outstanding cyclic stability (approximately 85.2% of the capacitance retention rate for 5000 cycles) and good mechanical flexibility (about 87.6% of its original capacitance after 500 bending times). Importantly, the device can possess a maximum energy density of 0.253mWh/cm3 at 0.5mA/cm2 and a maximum power density of 0.018 W/cm3 at 5mA/cm2. The results above indicate that RGO/PC/MnO2 composite has potential applications for flexible energy storage devices.