MWCNT/activated-carbon freestanding sheets: a different approach to fabricate flexible electrodes for supercapacitors

摘要

Wearable electronics require flexible supercapacitors with specially fabricated electrode materials, i.e., foldable and freestanding. Although activated carbon is the most used electrode's active material for aqueous supercapacitors, it is a challenge to pack the particulates into flexible electrodes. Typically, polytetrafluoroethylene binder and polymeric flexible substrate are used, rendering a large amount of inactive-material. Here, we successfully fabricated multiwalled carbon nanotube/activated-carbon (MWCNT-AC) freestanding sheet via a scalable surface-engineered tape-casting technique to be used as a flexible electrode for aqueous supercapacitors. Instead of focusing on improving MWCNTs as active materials, the sheets act as a conducting matrix that binds together the activated-carbon particulates. MWCNT-AC has a specific capacitance of 135.17Fg(-1) (123.9Fg(-1) after 1000 cycles) at 1Ag(-1) from -0.8 to 0.2V vs. Hg/HgO (in three-electrode cell).