Polymer superabsorbent from disposable diaper as a sustainable precursor for the development of stable supercapacitor electrode

Abstract

The development of stable and relatively high-performance supercapacitors from abundant and low-cost energy materials is a notable research effort. This study presents the development of hierarchical porous activated carbon using superabsorbent polymer (SAP_ACx) from abundant disposable diaper waste in a single-step phosphoric acid activation at different temperatures. The developed activated carbon materials were used as a supercapacitor electrode. The chemical activation and subsequent thermal treatment at 500 °C for 1 h tailored the pore size and surface area to 7.18 nm and 936 m2/g, respectively with a chemical modification that includes heteroatoms of oxygen (>30%) and phosphorous (>7%). Activation temperatures of 400 °C or 600 °C presented an adverse effect on the capacitive behavior of the developed SAP_AC electrode, whereas the highest capacitance was achieved at 500 °C. The SAP_AC500 electrode assembled in a symmetric supercapacitor showed capacitance retention of 83.9% after 20,000 charge/discharge cycles and maintained a coulombic efficiency of 99% during the whole stability test.