Delicate control of crystallographic Cu2O derived Ni–Co amorphous double hydroxide nanocages for high-performance hybrid supercapacitors: an experimental and computational investigation

Abstract

The reasonable design of the composition and hollow structure of electrode materials is beneficial for promoting the electrochemical properties and stability of electrode materials for high-performance supercapacitors, and it is of great significance to understand the inherent effect of these features on their performance. In this paper, the amorphous Ni–Co double hydroxide nanocages with hollow structures (Ni–Co ADHs) including quasi-sphere, cube and flower are delicately tailored via a Cu₂O template-assisted approach. By combining experimental characterization and density functional theory (DFT) calculations, we systematically study the morphological growth of Cu₂O templates under different conditions and the electrochemical performance of Ni–Co ADHs. Due to the coordination and synergistic effect between different components, the unique hollow structure and the nature of amorphous materials, Ni–Co ADHs deliver a high specific capacitance of 1707 F g⁻¹ at 1 A g⁻¹. The DFT calculations demonstrate that Ni–Co ADH nanocages exhibit an optimal redox reaction energy barrier and immensely promote the performance. In addition, a hybrid supercapacitor assembled with Ni–Co ADHs as a cathode and active carbon (AC) as an anode shows a high energy density of 33.8 W h kg⁻¹ at a power density of 850 W kg⁻¹ and exhibits an excellent cycling performance with a retention rate of 98% after 50 000 cycles. The successful synthesis of Ni–Co ADH nanocages, combined with rational computational simulations, indicates the excellent electrochemical performance and the potential utilization of amorphous hollow nanomaterials as electrodes for supercapacitors.