A high performance flexible solid-state asymmetric supercapacitor based on composite of reduced graphene oxide@dysprosium sulfide nanosheets and manganese oxide nanospheres

The reduced graphene oxide@dysprosium sulfide (rGO@Dy2S3) composite and MnO2 films are synthesized using successive ionic layer adsorption and reaction and from chemical bath deposition methods, respectively. Addition of rGO in Dy2S3 film enhances specific surface area from 40 to 78 m2g-1. Using these films flexible solid-state symmetric; rGO@Dy2S3//Dy2S3@rGO and asymmetric; MnO2//Dy2S3@rGO supercapacitor devices are fabricated. The solid-state asymmetric supercapacitor device exhibits specific energy of 41 Wh kg−1 at specific power 1330 W kg−1. The stability of asymmetric supercapacitor is 86% after 5000 cycles and flexibility of 82% at the bending angle 165°. This work highlights the first time use of rGO@Dy2S3 composite thin film material to fabricate symmetric and asymmetric supercapacitor devices and also demonstrates the superior performance of asymmetric device than symmetric one. [Display omitted] •For the first time, rGO@Dy2S3 thin film is synthesized using SILAR method.•The Brunarer-Emmett-Teller specific surface area of 78 m2 g−1 for rGO@Dy2S3 is higher than that of Dy2S3 (40 m2 g−1) sample.•rGO@Dy2S3 electrode shows highest electrochemical specific capacitance of 517 F g-1 at the scan rate of 5 mV s-1.•A flexible solid state AS device (MnO2//rGO@Dy2S3) showed specific energy of 41 Wh kg-1 with specific power 1330 W kg-1.