Microwave-assisted preparation of peanut shell-based activated carbons and their use in electrochemical capacitors

Activated carbons (ACs) were prepared from peanut shells by KOH activation under microwave heating and were used as electrode materials for electrochemical capacitors (ECs). The pore structure of the ACs was characterized by nitrogen adsorption and the electrochemical performance by galvanostatic charge-discharge and cyclic voltammetry. Results show that the ACs' specific surface area, total pore volume, specific capacitance, as well as energy density are maximized using an activation time from 6 to 10 min or KOH/peanut shell mass ratio from 0.6 to 2.0 under otherwise identical conditions. When the KOH/peanut shell mass ratio was 1.0, microwave power was 600 W and activation time was 8 min, the specific surface area of the resulting AC was 1277 m2/g and its energy density was 8.38 Wh/kg after 1000 cycles. The KOH activation of peanut shells with microwave heating is an efficient approach for the rapid preparation of low cost ACs for ECs.