Morphology-driven electrochemical properties of nickel-LDH and performance of symmetric button-type devices

Abstract

Nickel-based layered double hydroxides (LDHs) have garnered significant attention for energy storage applications owing to their unique interfacial characteristics and tunable structural properties. Despite this potential, precise morphological control of 3D/2D nanostructures remains a major challenge. In this study, we report a morphology-directed synthesis of nickel hydroxide (NH) nanostructures using two different halogen-containing precursors: ammonium iodide (AI) and ammonium chloride (ACl). The resulting AI-NH and ACl-NH samples exhibit distinct morphologies and physicochemical characteristics, influenced by the nature of the halide ions. Their electrochemical performance was systematically evaluated using both three-electrode and symmetric button-cell configurations. Among the two electrodes, the ACl-NH electrode achieved a higher specific capacity of 795 C/g at 1.5 A/g, compared to 601.5 C/g for AI-NH, and retained 97 % of its capacity over 6000 cycles at 24 A/g. This improvement is attributed to the increased surface area of ACl-NH (13.82 m²/g) versus AI-NH (9.58 m²/g). Furthermore, a symmetric device assembled with AI-NH and ACl-NH electrodes delivered a specific capacitance of 106.5 F/g at 1.5 A/g, an energy density of 37.8 Wh/kg at a power density of 1975.3 W/kg, and maintained 77% capacity retention over 8500 cycles.