One-pot synthesis of γ-MnS/reduced graphene oxide with enhanced performance for aqueous asymmetric supercapacitors

In this work, γ-MnS/reduced graphene oxide composites (γ-MnS/rGO) were prepared using a facile one-pot hydrothermal method. As an electrode material for supercapacitors, the γ-MnS/rGO-60 composite obtained under dosages of graphene oxide  was 60 mg and exhibited an enhanced specific capacitance of 547.6 F g^-1 at a current density of 1 A g^-1, and outstanding rate capability (65% capacitance retention at 20 A g^-1), with superior cycling stability and electrochemical reversibility. An asymmetric supercapacitor assembled from γ-MnS/rGO-60 composite and rGO (γ-MnS/rGO-60//rGO) showed a voltage window of 0-1.6 V and delivered a high energy density of 23.1 W h kg^-1 at a power density of 798.8 W kg^-1, and 15.9 W h kg^-1 at 4.5 kW kg^-1. Moreover, two such 1.0 × 1.0 cm² devices connected together in series easily light up a group of LED lights, showing its potential practical application as an attractive energy storage device.