Coffee waste-derived porous carbon based flexible supercapacitors

Nitrogen doped porous activated carbon was synthesized from coffee waste for flexible supercapacitor appli-cations. Nitrogen of 8.0 at% was doped, and specific capacitance of 139F g-1 at 0.5 A/g with specific energy of 12.5 Wh kg-1 and specific power of 202 W kg-1 was obtained for flexible supercapacitors. Eventually, high specific capacitance retention (90.5 %) as well as high coulombic efficiency (84.5 %) after 5,000 cycles with reliable flexibility were shown. The results demonstrated that the synthesized nitrogen-doped coffee waste derived carbon electrode could be used for the flexible supercapacitor electrodes.