Hollow Co 2 P nanoflowers assembled from nanorods for ultralong cycle-life supercapacitors.

Hollow Co2 P nanoflowers (Co2 P HNFs) were successfully prepared via a one-step, template-free method. Microstructure analysis reveals that Co2 P HNFs are assembled from nanorods and possess abundant mesopores and an amorphous carbon shell. Density functional theory calculations and electrochemical measurements demonstrate the high electrical conductivity of Co2 P. Benefiting from the unique nanostructures, when employed as an electrode material for supercapacitors, Co2 P HNFs exhibit a high specific capacitance, an outstanding rate capability, and an ultralong cycling stability. Furthermore, the constructed Co2 P HNF//AC ASC exhibits a high energy density of 30.5 W h kg-1 at a power density of 850 W kg-1 , along with a superior cycling performance (108.0% specific capacitance retained after 10 000 cycles at 5 A g-1 ). These impressive results make Co2 P HNFs a promising candidate for supercapacitor applications.