Electrochemical performance of a symmetric supercapacitor device designed using laser-induced multilayered graphene

This study demonstrates a facile and economical approach for fabricating laser-induced graphene (LIG), which results in improved electrochemical performance. Polyimide polymer was used as a starting material for LIG synthesis and irradiated under ambient conditions using a CO₂ laser. The prepared LIG samples were characterized by Raman spectroscopy and FTIR, which validated the formation of multilayered graphene containing sp² hybridized C＝C bonds. The FE-SEM revealed three-dimensional sheet-like structures, while HR-TEM images displayed lattice planes with an interplanar spacing of approximately 0.33 nm, corresponding to the (002) plane of graphene. The electrochemical performance of the as-prepared LIG samples demonstrated a remarkable areal specific capacitance (C_A) of 51 mF cm⁻² (170 F g⁻¹) at 1 mA cm⁻² (3.3 A g⁻¹) in a three-electrode configuration with 1M KOH as the aqueous electrolyte. The LIG electrodes produced an energy density of ~3.5 µWh cm⁻² and a power density of ~350 µW cm⁻², demonstrating significant energy storage capabilities. Additionally, the electrodes exhibited excellent cyclic stability, retaining 87% of their specific capacitance after 3000 cycles at 1 mA/cm². The symmetric supercapacitor fabricated with LIG electrodes and the tested 1M KOH electrolyte showed a specific capacitance of 23 mF cm⁻² and maintained excellent retention after 10,000 cycles, showing LIG’s potential for supercapacitor applications.