Enhancing the performance of activated carbon based scalable supercapacitors by heat treatment

A biomass based activated carbon was prepared by chemical activation using ZnCl2 as an activation agent. Some of the activated carbon sample was subjected to a further single step heat treatment at 800 degrees C under an inert atmosphere. Both carbon samples (untreated and heat treated) were tested as supercapacitor electrode materials. Further heat treatment significantly affected the surface properties of the carbon sample. Furthermore, a substantial enhancement in electrochemical performance was achieved in both aqueous and organic electrolytes despite its reduced specific surface area. The supercapacitor device based on the organic electrolyte exhibited higher rate capability than the aqueous one (KOH). The supercapacitor device assembled from the heat treated sample based on the organic electrolyte was scaled up from coin size to pouch size and the electrochemical response was maintained. Both coin and pouch supercapacitors showed good capacitance retention for over 10,000 cycles. This is comparable to the commercial high-rate activated carbon based supercapacitors.