High-performance asymmetric supercapacitors based on multilayer MnO2 graphene oxide nanoflakes and hierarchical porous carbon with enhanced cycling stability

Abstract

In this work, MnO2/GO (graphene oxide) composites with novel multilayer nanoflake structure, and a carbon material derived from Artemia cyst shell with genetic 3D hierarchical porous structure (HPC), are prepared. An asymmetric supercapacitor has been fabricated using MnO2/GO as positive electrode and HPC as negative electrode material. Because of their unique structures, both MnO2/GO composites and HPC exhibit excellent electrochemical performances. The optimized asymmetric supercapacitor could be cycled reversibly in the high voltage range of 0–2 V in aqueous electrolyte, which exhibits maximum energy density of 46.7 Wh kg−1 at a power density of 100 W kg−1 and remains 18.9 Wh kg−1 at 2000 W kg−1. Additionally, such device also shows superior long cycle life along with ∼100% capacitance retention after 1000 cycles and ∼93% after 4000 cycles.