Flexible Free-Standing Electrode of Nickel–Manganese Oxide with a Cracked-Bark Shape Composited with Aggregated Nanoparticles on Carbon Cloth for High-Performance Aqueous Asymmetric Supercapacitors

Abstract

Herein, a flexible free-standing cathode of nickel (Ni)-manganese (Mn) oxide (NMO) with a cracked-bark shape composited with aggregated nanoparticles on carbon cloth by simple one-step electrodeposition and the following annealing is reported. Benefiting from the high specific surface area because of the open structure and meanwhile from the effective stress relief due to the cracked-bark shape, a capacitance of up to 6768.7 mF cm–2 (1.0 mA cm–2), good rate performance (∼1416.8 mF cm–2 at 60.0 mA cm–2), and cycle stability are delivered by the optimized NMO cathode. An aqueous asymmetric supercapacitor assembled with the NMO cathode and commercial activated carbon anode has an energy density of 0.492 mWh cm–2 at 0.800 mW cm–2 and good capacitance retention of ∼82.3% after 15000 cycles at 20.0 mA cm–2 with ∼100% Columbic efficiency. In view of the excellent performance, high elemental abundance, eco-friendliness, and facile preparation, we believe that this study offers a useful attempt to construct high-performance aqueous AASCs.