Valorizing palm date wastes for supercapacitor electrode synthesis and evaluation

Climate and energy issues continue to drive researchers to develop fossil-free energy technologies that are both sustainable and scalable. In this work, date seeds (DS) are used to produce activated carbon (DSAC), which is then used as a supercapacitor electrode. The synthesis method uses KOH activation coupled with argon-gas flow calcination at 950 °C. The produced DSAC has a high specific surface area of 1374 m 2 /g and a turbostratic microporous structure (pore size = 1.14 nm), in addition to oxygen-containing functional groups (–C–O–, –OH). The DSAC electrochemical performance exhibits an electric double-layer capacitor (EDLC) with a minor pseudocapacitive contribution and delivers a 3-electrode specific capacitance of 1800 F/g at 4 A/g (estimated full-device specific capacitance is 450 F/g, energy, and power densities: 40 Wh/kg and 1440 W/kg, respectively). These numbers are remarkably higher than the current state-of-the-art carbon supercapacitor findings. Furthermore, it retains 83.3% of its initial discharge capacity after 2000 galvanostatic charge-discharge cycles at 10 A/g. Finally, the DSAC electrode performance is slightly enhanced with increasing the KOH concentration from 1 M to 3 M.