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

Muhammad Saleem Akhtar,1 Tomasz Wejrzanowski,1 Gabriela Komorowska,1 Emilia Choinska,1 Magdalena Laskowska,2 Zaeem Ur Rehman,3 Marcin Łapiński4 1Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw, Poland; 2Institute of Nuclear Physics Polish Academy of Sciences, Krakow, Poland; 3Faculty of Electronics, Telecommunications and Informatics, Gdańsk University of Technology, Gdańsk, Poland; 4Faculty of Applied Physics and Mathematics, Institute of Nanotechnology and Materials Engineering, Gdansk University of Technology, Gdańsk, PolandCorrespondence: Muhammad Saleem Akhtar, Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, Warsaw, 02-507, Poland, Email [email protected]: 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.Keywords: 2D hexagonal nanoflakes, microwave-assisted hydrothermal synthesis, specific capacitance, energy density, asymmetric supercapacitor