Activated carbons derived from polyethylene terephthalate for coin-cell supercapacitor electrodes

We successfully prepared activated carbon derived from polyethylene terephthalate (PET) via carbonization and subsequent activation under various conditions and applied it as active material for supercapacitors. In the activation, we used CO(2) for physical activation or KOH for chemical activation and varied the activation temperature from 600 °C to 1,000 °C. We found that CO(2) activation is unsuitable because of insufficient pore formation or low activation yield. Interestingly, PET-derived activated carbon obtained using KOH (PETK) at 700 °C–900 °C exhibited higher specific surface areas than YP50f, which is a commercial activated carbon. Furthermore, some PETKs even displayed a dramatic increase in crystallinity. In particular, the PET-derived activated carbon prepared at 900 °C with KOH (PETK900) had the highest retention rate at a high charge-discharge rate and better durability after 2500 cycles than YP50f. Furthermore, employing the same process that we used with the PET chips, we successfully converted waste PET bottles into activated carbon materials. Waste PET-derived activated carbons exhibited good electrochemical performance as active material for supercapacitors. We thus found chemical activation with KOH to be an appropriate method for manufacturing PET-derived activated carbon and PETKs derived both from PET chips and waste PET have considerable potential for commercial use as active materials for supercapacitors. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available for this article at 10.1007/s11814-023-1466-3 and is accessible for authorized users.