Coffee-derived activated carbon from second biowaste for supercapacitor applications
2021
Adan-Mas, Alberto | Alcaraz, Lorena | Arévalo-Cid, Pablo | López-Gómez, Félix. A. | Montemor, Fátima
The electrochemical energy storage performance of activated carbons (ACs) obtained from coffee-derived biowastes was assessed. ACs were obtained from spent coffee ground second waste, after polyphenol extraction, by means of a hydrothermal process followed by physical or chemical activation. The resulting materials exhibited microporous structures with a total specific area between 585 and 2330 m²·g⁻¹. Scanning electron microscopy (SEM) revealed a highly porous microstructure in the case of the chemically activated carbons, while physical activation led to a cracked micro-sized morphology. The electrochemical properties of the materials for supercapacitor applications were investigated in 1 M Na₂SO₄. After chemical activation, the coffee-derived material displayed a capacitance of 84 F·g⁻¹ at 1 A·g⁻¹ in a 1.9 V voltage window, with 70% capacitance retention at 10 A·g⁻¹ and 85% retention after 5000 cycles of continuous charge-discharge. This work demonstrates how coffee secondary biowaste can be conveniently activated to perform as electrochemical energy storage material, contributing to its revalorization and reinsertion in a circular economy.
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