Ternary Nanohybrid of Ni 3 S 2 /CoMoS 4 /MnO 2 on Nickel Foam for Aqueous and Solid-State High-Performance Supercapacitors.

To overcome the issues related to supercapacitor (SC) electrodes, such as high cost, low specific capacitance ( C s ), low energy density (ED), requirements for expensive binder, etc., binderless electrodes are highly desirable. Here, a new ternary nanohybrid is presented as a binder-free SC electrode based on Ni 3 S 2 , CoMoS 4 , and MnO 2 . A facile two-step hydrothermal route, followed by a short thermal annealing process, is developed to grow amorphous polyhedral structured CoMoS 4 and further wrap MnO 2 nanowires on Ni foam. This rationally designed binder-free electrode exhibited the highest C s of 2021 F g -1 (specific capacity of 883.8 C g -1 or 245.5 mAh g -1 ) at a current density of 1 A g -1 in 1 M KOH electrolyte with a highly porous surface morphology. This electrode material exhibited excellent cycling stability (90% capacitance retention after 4000 cycles) due to the synergistic contribution of individual components and advanced surface properties. Furthermore, an aqueous binder-free asymmetric SC based on this ternary composite exhibited an ED of 20.7 Wh kg -1 , whereas a solid-state asymmetric SC achieved an ED of 13.8 Wh kg -1 . This nanohybrid can be considered a promising binder-free electrode for both aqueous and solid-state asymmetric SCs with these remarkable electrochemical properties.