An advanced hybrid supercapacitor constructed from rugby-ball-like NiCo2Se4 yolk-shell nanostructures

Electrode materials based on the yolk-shell structure are of considerable importance in the energy-storage field. Herein, rugby-ball-like NiCo2Se4 yolk-shell nanostructures (RB-NCS) are successfully synthesized and developed as an attractive cathode electrode material for hybrid supercapacitors. Benefiting from the high porosity of the obtained structure and desirable electrical conductivity, the as-designed RB-NCS electrode presents a prominent capacity of 258.1 mA h g(-1) at 1 A g(-1) and an impressive longevity of 92.2% over 14 000 cycles at 20 A g(-1); meanwhile, a high coulombic efficiency of approximate to 98.1% is achieved. Considering the achieved excellent results, a hybrid supercapacitor was fabricated with the RB-NCS and AC (activated carbon) materials as the cathode and anode electrodes, respectively, in KOH electrolyte (6 M). The as-fabricated apparatus (RB-NCS(+)||AC(-)) delivered a desirable capacity of 71 mA h g(-1) at 1 A g(-1) with a good capacity retention of 68.9%. Also, the RB-NCS(+)||AC(-) apparatus reflected maximum energy and power densities of 56.9 W h kg(-1) and 812.6 W kg(-1) at 1 A g(-1), respectively.