Activated carbon from olive tree pruning residue for symmetric solid-state supercapacitor

The scientific community is focusing on developing supercapacitors with high capacitance, power and energy from waste-derived electrode materials and low-toxic aqueous electrolytes that can provide an advance in energy storage as well as the care for the environment. This work presents the development of a symmetric solid-state supercapacitor with activated carbon from olive pruning. Activated carbons were synthesized by chemical and physical methods varying their conditions. The physicochemical characterization determined that chemically activated carbons provided the highest surface areas, greater than 2000 m2 g−1. The electrochemical performance of chemically activated carbons was superior to physically activated carbons due to the high surface area and the developed pore structure that promote capacitances of up to 410 F g−1. Three symmetric solid-state supercapacitors with chemically activated carbon as electrode material and PVA-KOH hydrogel as electrolyte were assembled, and windows potential and drying time of the membrane were evaluated. An excellent performance supercapacitor was developed with electrode materials from olive pruning waste, which presented a capacitance of 1.15 F at 5 mA, a voltage of 1.2 V and equivalent series resistance of 1.42 Ω. These results present a promising way to develop competitive energy storage devices using agro-industrial waste to produce electrode materials.