Effect of freezing pretreatment on the performance of activated carbon from coconut shell for supercapacitor application

To reduce the KOH consumption during the activating process of activated carbon (AC) preparing, freezing pretreatment was carried out on coconut shell (CS), which resulted in increased specific surface area and total pore volume in the pyrolysed carbon from frozen CS (FCS). ACs were prepared from CS and FCS with different KOH/carbon ratios. Compared with AC from CS with KOH/carbon ratio of 5:1, Frozen AC from FCS with KOH/ carbon ratio of 3:1 possesses larger specific surface area (2410 m2 g−1), wider average pore diameter (3.35 nm), higher specific capacitance (395 F g−1 at a discharging current density of 0.3 A g−1) and better power performance.