Phase-Controlled Construction of Copper-Leaf-like 2D NiS for Enhanced Supercapacitor Performance: A Supercritical Fluid Process

Abstract

This study investigates a rapid and straightforward approach for constructing phase-controlled two-dimensional NiS nanosheets using the supercritical fluid (SCF) method. Through structural and morphological analyses, it is observed that the single-phase NiS nanosheets exhibit a rough and hierarchical surface, potentially offering a versatile electroactive area for energy storage. The electrochemical performance of fabricated single-phase NiS-based supercapacitors are measured in both three-electrode and two-electrode systems. In asymmetric supercapacitor (ASC) configuration with H2SO4 electrolyte, α-NiS demonstrated a remarkably high specific areal capacitance of 1664.61 mF.cm-2 at a current density of 1mA.cm-2. In asymmetric supercapacitor mode, NiS nanostructures achieved an exceptionally high volumetric energy density of 1953.61 mWh.cm-3 at a highest power density of 45.5W.cm-3. Furthermore, it showed an outstanding cycling performance of 95.77% retention after 5000 cycles at a high current density of 10mA.cm-2.