Fabrication and characterization of laser scribed supercapacitor based on polyimide for energy storage

Abstract

Recently, supercapacitors have attracted a tremendous amount of attention as energy-storage devices due to their high-power density, fast charge-discharge ability, excellent reversibility, and long cycling life. In this research work, we demonstrate a laser scribed super capacitor based on polyimide (PI) substrate for the storage of electrical energy. PI substrate of thickness 200μm and area 1cm × 1cm was reduced by a laser engraver with a 450 nm wavelength in the form of stackable supercapacitor electrodes. Although, PI itself exhibits non-conductive behavior; however, by laser irradiation we change the surface properties of PI and reduce its resistance. The chemical property of irradiated PI was characterized with XRD where the carbon peak was observed at 2θ = 25.44, which confirms the reduction of PI material in to a graphene-like substance. The electrical conductivity was analyzed with a probe station and observed to be 1.6mS. Two conductive regions were assembled into a capacitor device by sandwiching a PVA/H3PO4 electrolyte in between. During the charging and discharging characterization of the capacitor device, current density was observed to be 1.5mA/cm2. Capacitance versus voltage analysis was carried out and the device showed 75mF/cm2 against a voltage sweep of ±2V. The galvanostatic charging and discharging curve shows a symmetric behavior with respect to time exhibiting the stability and durability of the device.