| Summary: | The electrical double-layer supercapacitance performance of the nanoporous carbons prepared from the <i>Phyllanthus emblica</i> (Amala) seed by chemical activation using the potassium hydroxide (KOH) activator is reported. KOH activation was carried out at different temperatures (700–1000 °C) under nitrogen gas atmosphere, and in a three-electrode cell set-up the electrochemical measurements were performed in an aqueous 1 M sulfuric acid (H<sub>2</sub>SO<sub>4</sub>) solution. Because of the hierarchical pore structures with well-defined micro- and mesopores, <i>Phyllanthus emblica</i> seed-derived carbon materials exhibit high specific surface areas in the range of 1360 to 1946 m<sup>2</sup> g<sup>−1</sup>, and the total pore volumes range from 0.664 to 1.328 cm<sup>3</sup> g<sup>−1</sup>. The sample with the best surface area performed admirably as the supercapacitor electrode-material, achieving a high specific capacitance of 272 F g<sup>−1</sup> at 1 A g<sup>−1</sup>. Furthermore, it sustained 60% capacitance at a high current density of 50 A g<sup>−1</sup>, followed by a remarkably long cycle-life of 98% after 10,000 subsequent charging/discharging cycles, demonstrating the electrode’s excellent rate-capability. These results show that the <i>Phyllanthus emblica</i> seed would have significant possibilities as a sustainable carbon-source for the preparing high-surface-area activated-carbons desired in high-energy-storage supercapacitors.
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