Nanoflake-Modulated La₂ Se₃ Thin Films Prepared for an Asymmetric Supercapacitor Device

La₂ Se₃ nanoflakes were prepared from an aqueous medium by means of a chemical-bath deposition method and were later utilized as a supercapacitor electrode. X-ray diffraction (XRD), Fourier transform Raman (FT Raman), field-emission scanning electron microscopy (FESEM), and contact-angle measurement techniques were used to study the structural, morphological, and wettability properties of La₂ Se₃ films. The XRD study confirmed the cubic crystal structure of the La₂ Se₃ film. The surface morphology and wettability studies revealed the nanoflake morphology with a hydrophilic surface, which could be beneficial to electrochemical reactions. The electrochemical performance of the La₂ Se₃ nanoflakes was evaluated by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques. The La₂ Se₃ nanoflake electrode exhibited a maximum specific capacitance of 331 F g^-1 at a scan rate of 5 mV s^-1 . An electrochemical impedance study confirmed that the La₂ Se₃ nanoflake electrode has a better supercapacitive behavior in an aqueous electrolyte. The asymmetric supercapacitor device based on the La₂ Se₃ electrode in aqueous electrolyte exhibited good specific capacitance, excellent charge/discharge properties, and superior long-term cycling stability.