Activated carbon derived from coconut coir pith as high performance supercapacitor electrode material

In this study, activated carbons were synthesized from coconut coir pith, an inexpensive and abundant type of biomass in Thailand. The coconut coir pith was activated by a combined physical and chemical activation route, using NaOH-to-char ratios of 1:1, 2:1 and 3:1 by weight. A high surface area of 2056 m2 g−1 was achieved with NaOH-to-char weight ratio of 3:1. Using this activated carbon in a symmetrical cell with aqueous electrolyte, high capacitance values were achieved. The specific capacitance values obtained were 232.3 F g−1 at 0.1 A g−1 and 192.0 F g−1 at 1 A g−1. Long-term cycling tests at 0.5 A g−1 showed 95.4% capacitance retention after 5000 cycles. The high specific capacitance was attributed to the high micropore volume. The superior rate capability was from the interconnected pore structure of the activated carbon which allowed for efficient ion transport.