Conductive carbon spheres-supported nickel-cobalt selenide nanoparticles as a high-performance and long-life electrode for supercapacitors

Abstract The electrode materials with core-shell heterostructure draw researchers' attention in the fabrication of supercapacitors (SCs), which can reduce cost and prolong service lifespans. Herein, nickel‑cobalt selenide nanoparticles, which are anchored on carbon microsphere to form core-shell heterostructure composite, exhibit excellent specific capacitance (960 F g−1) and superior cycling lifetime (85% after 2000 cycles). Furthermore, a new asymmetric supercapacitor (ASC) is created by utilizing C-20@(Ni, Co)0.85Se and AC as cathode and anode. The C-20@(Ni, Co)0.85Se // AC ASC exhibits the largest energy density of 34.44 W h kg−1 at a power density of 1125.23 W kg−1 and superior cycling lifetime with 81.5% of capacitance retention after 5000 cycles. Thus, C-20@(Ni, Co)0.85Se // AC ASC is known as potential electrode materials for ASC devices.