Structural evolution and sulfuration of nickel cobalt hydroxides from 2D to 1D on 3D diatomite for supercapacitors

Abstract

Transition metal nickel–cobalt hydroxides are widely used as electrode materials for supercapacitors due to their intriguing active component properties. Nevertheless, their aggregation problem and poor electrical conductivity severely hinder their further application as supercapacitor electrodes. Herein, we propose a controllable route for the preparation of nickel–cobalt hydroxide supported on 3D diatomite. The structural evolution of nickel–cobalt hydroxide in different proportions from 2D to 1D was achieved by controlling the raw materials. The sulfuration modification of samples with outstanding performance was also studied via the hydrothermal method. The NiCo–OH@DE nanowires were found to be better than the NiCo-LDH@DE nanosheets. On comparing the samples after sulfuration, it was found that Ni2Co1S@DE sulfurated by Ni2Co1–OH@DE had the best electrochemical performance among all samples. At a current density of 1 A g⁻¹, its specific capacitance reached 917.5 F g⁻¹, and the fabricated Ni2Co1S@DE//AG ASC device exhibited a high energy density of 24 W h kg⁻¹ at 6718 W kg⁻¹, and more than 75% of the capacitance was preserved after 2000 charge/discharge cycles, delivering a stable cycling performance. The impressive performance of the abovementioned Ni2Co1S@DE revealed an effective fabricating strategy for optimizing electrode materials, offering a promising future for high-performance hybrid energy storage devices.