Microstructural and electrochemical evaluations of Ti-substituted LaFe₀.₈Cu₀.₂₋ₓTiₓO nanostructures with nascent vacancies

This study investigates the impact of Ti substitution on the microstructural and electrochemical properties of LaFe_0.8Cu_0.2–xTi_xO (x = 0, 0.05, and 0.1) perovskite oxide, which was synthesized via a rapid microwave-assisted method followed by calcination at 800°C for supercapacitor applications. XRD refinement revealed that Ti substitution induces nominal unit cell distortion and increases nascent vacancies. Raman and FTIR spectroscopy, which are sensitive to microstrain, supported the microstructural distortions indicated by XRD. Analysis of the Raman and FTIR spectra identified two prominent bands between 600–750 cm^–1, associated with O/B site vacancies, with peak variations consistent with XRD's dislocation density findings. XPS data indicated that Ti substitution synergistically influences microstructural properties, enhancing vacancy formation. Electrochemically, electrodes and an all-solid-state asymmetric supercapacitor device incorporating LaFe_0.8Cu_0.2–xTi_xO exhibited promising energy storage capabilities. Increased Ti substitution in the electrode material achieved an impressive specific capacity of 488 C/g at a current density of 0.3 A/g and demonstrated excellent rate capability. The device displayed energy and power densities of 14.67 Wh/kg and 1199 W/kg, respectively, with a 98% retention of specific capacitance after 10,000 cycles, underscoring the material's durability in the device.