Microwave-Assisted Synthesis of Novel Ni3S2/Ce2O2S 2D Hexagonal Nanoflakes for High-Performance Asymmetric Supercapacitors.

Abstract

Introduction: High-energy-density supercapacitors require advanced electrode materials with superior pseudocapacitive behavior and stability. This study focuses on the design and development of binder-free pseudocapacitive electrodes composed of two-dimensional (2D) hexagonal nickel/cerium sulfide nanoflakes, which are directly synthesized on nickel foam. The aim was to achieve enhanced electrochemical performance through novel 2D nanoarchitectures and improved charge transfer dynamics.

Methods: The nickel/cerium sulfide nanoflakes were fabricated via a microwave-assisted hydrothermal synthesis. Structural and morphological characteristics were analyzed using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Electrochemical properties were evaluated through cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy in both half-cell and asymmetric supercapacitor (ASC) configurations.

Results and discussion: The synthesized electrode demonstrated a high specific capacitance of 5286 F/g, an energy density of 222.09 Wh/kg, and a power density of 687.19 W/kg at 2.5 A/g in the half-cell system. The ASC device, utilizing nickel/cerium sulfide nanoflakes as the positive electrode and graphene nanoplatelets (GNPs)@Ni foam as the negative electrode, achieved an energy density of 77.51 Wh/kg and a power density of 797.25 W/kg at 1 A/g. The ASC also demonstrated excellent cyclic durability, retaining 84% of its capacitance after 10,000 cycles.

Conclusion: The in situ-grown 2D hexagonal nickel/cerium sulfide nanoflakes exhibit outstanding pseudocapacitive behavior and electrochemical stability, underscoring their strong potential for next-generation high-performance asymmetric supercapacitors.