Activated carbon derived from melaleuca barks for outstanding high-rate supercapacitors

Activated carbon (AC) was prepared via carbonizing melaleuca bark in an argon atmosphere at 600 °C followed with KOH activation for high-rate supercapacitors. This AC electrode has a high capacitance of 233 F g⁻¹ at a scan rate of 2 mV s⁻¹ and an excellent rate capability of ∼80% when increasing the sweep rate from 2 to 500 mV s⁻¹. The symmetric supercapacitor assembled by the above electrode can deliver a high energy density of 4.2 Wh kg⁻¹ with a power density of 1500 W kg⁻¹ when operated in the voltage range of 0–1 V in 1 M H₂SO₄ aqueous electrolyte while maintaining great cycling stability (less than 5% capacitance loss after 10 000 cycles at sweep rate of 100 mV s⁻¹). All the outstanding electrochemical performances make this AC electrode a promising candidate for potential energy storage application. (paper)