Heterogeneous structure and defect engineering mutual coupling of NiCoP@NiCo-LDH for high-performance supercapacitors.

• Design defective NiCoP@NiCo-LDH heterostructured electrode material with cationic vacancies. • Ni and Co vacancies and heterostructure cooperate to facilitates charge redistribution. • 3D microspheres structure can facilitate rapid electron transfer and electrolyte transport. • A high energy density of 94.44 Wh kg−1 was attained at a power density of 850 W kg−1. • DFT elucidates the mechanism of charge transport and storage at the heterointerface as well as the bimetallic vacancy. For hybrid supercapacitors, electrode materials possessing rational cation vacancy heterostructures are crucial in enhancing energy density and conductivity. Herein, we propose a facile strategy to synthesize defective NiCoP@NiCo-LDH (v-NPC-LDH) heterostructures with nanosheets-covered microspheres by two-step electrodeposition, and N-methylpyrrolidone solvent heat treatment. In combination with electrochemical tests and density functional theory (DFT), which clarifies that the charge redistribution generated at the heterogeneous interface facilitates charge transport. In particular, the presence of nickel and cobalt vacancies greatly increases the intrinsic electronic conductivity of NiCo-LDH and promotes the charge storage process. In a three-electrode system, the v-NPC-LDH electrode displays a conspicuously great specific charge of 1110 C g−1, and the specific capacity of v-NPC-LDH electrode material is 85.4 % after 10,000 cycles at 20 A g−1. In addition, the hybrid supercapacitor v-NPC-LDH//AC achieves a high energy density (94.44 Wh kg−1) at a power density of 850 W kg−1. Specifically, two series-connected v-NPC-LDH//AC HSCs can light up LED lamps for 10 min, which indicates their potential application. [Display omitted] [ABSTRACT FROM AUTHOR]