Structure-Engineered Core–Shell Ni–Co–O/NiCo-LDH Nanospheres as High-Performance Supercapacitor Electrodes

Abstract

The development of a novel electrode material for energy storage devices is a grand challenge. Here, through a rational design of the structure, the electrochemical performance of the prepared sample could be improved while enhancing the conductivity and the synergistic effect of its components. Herein, we constructed a core–shell composite named Ni–Co–O/NiCo-LDH as the electrode material by a self-template method, which comprised hydrothermal and annealing steps. The as-prepared material exhibited a Chinese chestnut-like structure, and the core–shell structure was based on nanoneedles. The pseudocapacitance characteristics of the Ni–Co–O/NiCo-LDH electrode were significantly improved due to the good electrical conductivity of the core material and the unique core–shell structure, which led to a high electrochemical performance, reaching a high specific capacitance of 1434 F g−1 at the current density of 1 A g−1. When assembled in a device with activated carbon (AC) as the negative electrode, the supercapacitor showed an energy density of 26 Wh kg−1 at a power density of 807 W kg−1. Simultaneously, the device showed an excellent cycle stability, with 95% capacity retention after 3600 cycles at a current density of 6 A g−1, which could largely widen the application of the supercapacitor.