Flexible symmetric supercapacitor with ultrahigh energy density based on NiS/MoS₂@N-rGO hybrids electrode

A new type of 3D NiS/MoS₂@N-doped reduced graphene oxide (NiS/MoS₂@N-rGO) hybrid composite is presented and its super-capacitive performance is studied. NiS/MoS₂@N-rGO hybrid is synthesized via an easy and cost-effective hydrothermal route. By combining nickel sulfide and molybdenum disulfide with N-reduced graphene oxide, the as-prepared sample demonstrates a mesoporous nanostructure that increases the accessible area of the electrolyte ions. Due to the synergistic effect in the 3D network, such NiS/MoS₂@N-rGO hybrid is used as electrode and it demonstrates a highly specific capacity of 2225 F/g at a current density of 1 A/g, and a good rate of 1347.3 F/g at 10 A/g. Furthermore, we also test a full symmetric supercapacitor based on NiS/MoS₂@N-rGO, which displays excellent capacitive property up to 1028 F/g at 1 A/g, with high energy and good power density up to 35.69 W h/kg and 601.8 W/kg, and good cycle stability up to 94.5% initial capacitive retention after 50,000 loops. Moreover, the symmetric supercapacitor demonstrates excellent flexibility under different bending conditions.