Hierarchical Co3O4@Ni(OH)2 core-shell nanosheet arrays for isolated all-solid state supercapacitor electrodes with superior electrochemical performance

- Two-dimensional Co3O4@Ni(OH)2 core-shell arrays deposited on nickel foam was fabricated.
- The Ni(OH)2 shell belongs to α-Ni(OH)2, possessing high theoretical capacitance.
- The core-shell electrode exhibits enhanced electrochemical performance.
- The all solid-state asymmetric capacitor obtains high energy and power densities.

Due to the unique properties of two-dimensional nanomaterials, an attempt to fabricate core-shell materials based on two-dimensional nanomaterials for supercapacitor is provided. Employing hydrothermal reactions, Co3O4@Ni(OH)2 nanosheet core-shell structure, directly grown onto the surface of nickel foam substrate, was successfully fabricated with enhanced electrochemical properties. Ni(OH)2 nanosheets anchored on Co3O4 with two-dimensional structure effectively facilitate convenient ion diffusion and increase the active surface reacting with electrolyte. The as-fabricated material displays outstanding electrochemical performance, including high specific capacitance (1306 F g−1), fast charge-discharge rate and excellent cycling stability. Furthermore, an all solid-state asymmetric supercapacitor, based on Co3O4@Ni(OH)2 and active carbon as positive and negative electrodes respectively, was also assembled, exhibiting a maximum energy density of 40 Wh kg−1 and high power density of 3455 W kg−1 as well as advantageous cycling stability (90.5% capacitance retention after 5000 cycles). The two-dimensional core-shell supercapacitor electrode, fabricated in our work, provides an effective solution to meet the growing demand for practical energy applications.

Two-dimensional Co3O4@Ni(OH)2 core-shell arrays, directly grown on nickel foam substrate as binder free electrode with superior electrochemical performance, have been successfully fabricated through a facile two-step hydrothermal method. Furthermore, an all-solid state asymmetric supercapacitor device based on Co3O4@Ni(OH)2 and active carbon as positive electrode and negative electrode respectively, exhibits a maximum energy density of 40.0 W h kg−1 as well as a maximum power density up to 3455 W kg−1, demonstrating its potential utilization for energy storage-conversion applications.130