KOH-activated microstructured carbon derived from Asclepias syriaca floss for extraordinary 200k cycle stability in supercapacitors
Abstract
We report a novel carbon material obtained from low-density fibrous fur-like biowaste Asclepias syriaca (milkweed) floss for use as low-cost and efficient electrodes in electrochemical double layer capacitors (EDLCs). Milkweed floss is pyrolyzed to carbon (MW) and activated with widely available and commonly used KOH as a porogen at 700 and 800 °C (MW-1 and MW-2). From Brunauer–Emmett–Teller (BET) analysis, the surface area and pore volume of MW-2 are found to be twice those of MW-1. Morphological and Raman analysis of MW-2 indicates high surface etching/defects. The high surface area and microporosity of MW-2 are due to the vaporized state of metallic potassium during chemical activation. MW-2 exhibits better electrochemical performance in a three-electrode system. A symmetric coin cell (SCC) designed using MW-2 in 1 M KOH exhibits high energy density (ED: 37.6 W h kg−1) and power density (PD: 19.1 kW kg−1) and low solution (Rs: 1.86 Ω) and charge transfer (Rct: 3.24 Ω) resistance with remarkably high stability after 200k cycles. SCC retains 80% specific capacitance (Cs) with 100% coulombic efficiency and almost negligible change in Rs or Rct values after 200 000 cycles, thus proving its high supercapacitance efficiency. Furthermore, six fabricated SCCs were connected in series and shown to power a flashlight.
Please wait while we load your content...
