ZnCl2-Activated Nanoporous Carbon Materials from Phyllanthus emblica Seed for High-Performance Supercapacitors

This study reports the synthesis of an activated nanoporous carbon material from Phyllanthus emblica (Amala)—a biomass material which is an eco-friendly, economical, and sustainable precursor used to prepare activated carbon using zinc chloride (ZnCl2) activation at various temperatures (500–700 °C) under a nitrogen gas atmosphere. A sample that was carbonized at 700 °C (AmC_Z700) attained a high specific surface area of 1436 m2 g−1 and a total pore volume of 0.962 cm3 g−1, and, when used in an electrode, showed excellent supercapacitance performance, attaining a high specific capacitance of 263 F g−1 at a current density of 1 A g−1, followed by 55% capacitance retention at 50 A g−1. Additionally, the assembled symmetric supercapacitor cell, when operated at 1.2 V, delivered an energy density of 8.9 Wh kg−1 at a power density of 300 W kg−1 and exhibited an excellent cycle life of 95% after 10,000 successive charge/discharge cycles, demonstrating the substantial potential of Phyllanthus emblica seed-derived carbon materials for the creation of high-performance supercapacitors.