A novel P-doped Ni0.5Cu0.5Co2O4 sphere with a yolk-shell hollow structure for high-energy–density supercapacitor

P-doped multi-metal oxide is an effective method to improve its electrochemical energy storage performance. Herein, a novel P-doped ternary metal oxide (P-Ni 0.5 Cu 0.5 Co 2 O 4 ) with a yolk-shell hollow structure is reasonably prepared and used as electrode material for supercapacitors. The as-prepared electrode has significantly improved conductivity and capacity, with a high specific capacitance of 1570.2F g −1 in a three-electrode system. Furthermore, the as-assembled P-Ni 0.5 Cu 0.5 Co 2 O 4 //activated carbon supercapacitor possesses an ultra-high energy density of 118.6 W h kg −1 and stable cyclic performance.