Enhancing the efficiency of flexible all-solid-state supercapacitor via cadmium decontamination of water

Abstract

The need for efficient energy storage systems and the problem of toxic waste disposal after heavy metal adsorption can be solved by using Cd adsorbed adsorbent as an electrode for portable flexible supercapacitor. In this regard, cellulose extracted from rice straw, modified by sulphate intercalated NiAl LDH, could achieve a maximum cadmium removal of 57.4 mg g−1 at 25 °C. The cadmium-saturated adsorbent was heat treated to stabilize the cadmium, leading to Cd-doped NiO and NiAl2O4/carbon composite formation, as revealed from the FESEM, HRTEM, and XRD analyses. The Cd-doping led to an increment in the electrochemical performance of the samples, as shown by the 3-electrode analysis. The Cd-doped composite was used as a cathode to fabricate an all-solid-state flexible asymmetric supercapacitor which had a high specific capacitance of 110 F g−1 with energy density of 15.3 W h kg−1 and power density of 999.3 W kg−1 at 1 A g−1. The device showed good flexible nature with also retaining around 100 % of the initial specific capacitance after 10,000 cycles. The device also fared in practical applications where three devices connected in series could light up a red LED.